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Water: Microbial & Disinfection Byproducts Rules

National Primary Drinking Water Regulations: Disinfectants and Disinfection Byproducts

 

[Federal Register: December 16, 1998 (Volume 63, Number 241)]

[Rules and Regulations]

[Page 69389-69476]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr16de98-17]





[[Page 69389]]



_______________________________________________________________________



Part IV











Environmental Protection Agency











_______________________________________________________________________







40 CFR Parts 9, 141, and 142







National Primary Drinking Water Regulations: Disinfectants and

Disinfection Byproducts; Final Rule





[[Page 69390]]







ENVIRONMENTAL PROTECTION AGENCY



40 CFR Parts 9, 141, and 142



[WH-FRL-6199-8]

RIN 2040-AB82





National Primary Drinking Water Regulations: Disinfectants and

Disinfection Byproducts



AGENCY: Environmental Protection Agency (EPA).



ACTION: Final rule.



-----------------------------------------------------------------------



SUMMARY: In this document, EPA is finalizing maximum residual

disinfectant level goals (MRDLGs) for chlorine, chloramines, and

chlorine dioxide; maximum contaminant level goals (MCLGs) for four

trihalomethanes (chloroform, bromodichloromethane,

dibromochloromethane, and bromoform), two haloacetic acids

(dichloroacetic acid and trichloroacetic acid), bromate, and chlorite;

and National Primary Drinking Water Regulations (NPDWRs) for three

disinfectants (chlorine, chloramines, and chlorine dioxide), two groups

of organic disinfection byproducts (total trihalomethanes (TTHMs)--a

sum of the four listed above, and haloacetic acids (HAA5)--a sum of the

two listed above plus monochloroacetic acid and mono-and dibromoacetic

acids), and two inorganic disinfection byproducts (chlorite and

bromate). The NPDWRs consist of maximum residual disinfectant levels

(MRDLs) or maximum contaminant levels (MCLs) or treatment techniques

for these disinfectants and their byproducts. The NPDWRs also include

monitoring, reporting, and public notification requirements for these

compounds. This document includes the best available technologies

(BATs) upon which the MRDLs and MCLs are based. The set of regulations

promulgated today is also know as the Stage 1 Disinfection Byproducts

Rule (DBPR). EPA believes the implementation of the Stage 1 DBPR will

reduce the levels of disinfectants and disinfection byproducts in

drinking water supplies. The Agency believes the rule will provide

public health protection for an additional 20 million households that

were not previously covered by drinking water rules for disinfection

byproducts. In addition, the rule will for the first time provide

public health protection from exposure to haloacetic acids, chlorite (a

major chlorine dioxide byproduct) and bromate (a major ozone

byproduct).

    The Stage 1 DBPR applies to public water systems that are community

water systems (CWSs) and nontransient noncommunity water systems

(NTNCWs) that treat their water with a chemical disinfectant for either

primary or residual treatment. In addition, certain requirements for

chlorine dioxide apply to transient noncommunity water systems

(TNCWSs).



EFFECTIVE DATE: This regulation is effective February 16, 1999.

Compliance dates for specific components of the rule are discussed in

the Supplementary Information Section. The incorporation by reference

of certain publications listed in today's rule is approved by the

Director of the Federal Register as of February 16, 1999.



ADDRESSES: Public comments, the comment/response document, applicable

Federal Register documents, other major supporting documents, and a

copy of the index to the public docket for this rulemaking are

available for review at EPA's Drinking Water Docket: 401 M Street, SW.,

Washington, DC 20460 from 9 a.m. to 4 p.m., Eastern Standard Time,

Monday through Friday, excluding legal holidays. For access to docket

materials, please call 202/260-3027 to schedule an appointment and

obtain the room number.



FOR FURTHER INFORMATION CONTACT: For general information contact, the

Safe Drinking Water Hotline, Telephone (800) 426-4791. The Safe

Drinking Water Hotline is open Monday through Friday, excluding Federal

holidays, from 9:00 am to 5:30 pm Eastern Time. For technical

inquiries, contact Tom Grubbs, Office of Ground Water and Drinking

Water (MC 4607), U.S. Environmental Protection Agency, 401 M Street SW,

Washington, DC 20460; telephone (202) 260-7270. For Regional contacts

see Supplementary Information.



SUPPLEMENTARY INFORMATION: This regulation is effective 60 days after

publication of Federal Register document for purposes of the

Administrative Procedures Act and the Congressional Review Act.

Compliance dates for specific components of the rule are discussed

below. Solely for judicial review purposes, this final rule is

promulgated as of 1 p.m. Eastern Time December 30, 1998, as provided in

40 CFR 23.7.

    Regulated entities. Entities regulated by the Stage 1 DBPR are

community and nontransient noncommunity water systems that add a

disinfectant during any part of the treatment process including a

residual disinfectant. In addition, certain provisions apply to

transient noncommunity systems that use chlorine dioxide. Regulated

categories and entities include:



----------------------------------------------------------------------------------------------------------------

                Category                                      Examples of regulated entities

----------------------------------------------------------------------------------------------------------------

Industry...............................  Community and nontransient noncommunity water systems that treat their

                                          water with a chemical disinfectant for either primary of residual

                                          treatment. In addition, certain requirements for chlorine dioxide

                                          apply to transient noncommunity water systems.

State, Local, Tribal, or Federal         Same as above.

Governments.

----------------------------------------------------------------------------------------------------------------



    This table is not intended to be exhaustive, but rather provides a

guide for readers regarding entities likely to be regulated by this

action. This table lists the types of entities that EPA is now aware

could potentially be regulated by this action. Other types of entities

not listed in this table could also be regulated. To determine whether

your facility is regulated by this action, you should carefully examine

the applicability criteria in Sec. 141.130 of this rule. If you have

questions regarding the applicability of this action to a particular

entity, contact one of the persons listed in the preceding FOR FURTHER

INFORMATION CONTACT section or the Regional contacts below.



Regional Contacts



I. Kevin Reilly, Water Supply Section, JFK Federal Bldg., Room 203,

Boston, MA 02203, (617) 565-3616

II. Michael Lowy, Water Supply Section, 290 Broadway 24th Floor, New

York, NY 10007-1866, (212) 637-3830

III. Jason Gambatese, Drinking Water Section (3WM41), 1650 Arch Street,

Philadelphia, PA 19103-2029, (215) 814-5759



[[Page 69391]]



IV. David Parker, Water Supply Section, 345 Courtland Street, Atlanta,

GA 30365, (404) 562-9460

V. Miguel Del Toral, Water Supply Section, 77 W. Jackson Blvd.,

Chicago, IL 60604, (312) 886-5253

VI. Blake L. Atkins, Drinking Water Section, 1445 Ross Avenue, Dallas,

TX 75202, (214) 665-2297

VII. Ralph Flournoy, Drinking Water/Ground Water Management Branch, 726

Minnesota Ave., Kansas City, KS 66101, (913) 551-7374

VIII. Bob Clement, Public Water Supply Section (8P2-W-MS), 999 18th

Street, Suite 500, Denver, CO 80202-2466, (303) 312-6653

IX. Bruce Macler, Water Supply Section, 75 Hawthorne Street, San

Francisco, CA 94105, (415) 744-1884

X. Wendy Marshall, Drinking Water Unit, 1200 Sixth Avenue (OW-136),

Seattle, WA 98101, (206) 553-1890



Abbreviations Used in This Document



AWWA: American Water Works Association

AWWSCo: American Water Works Service Company

BAT: Best available technology

BDCM: Bromodichloromethane

CDC: Centers for Disease Control and Prevention

C.I.: Confidence Intervals

CMA: Chemicals Manufacturers Association

CPE: Comprehensive performance evaluation

CWS: Community water system

DBCM: Dibromochloromethane

DBP: Disinfection byproducts

D/DBP: Disinfectants and disinfection byproducts

DBPR: Disinfection Byproducts Rule

DBPRAM: Disinfection byproducts regulatory analysis model

DCA: Dichloroacetic acid

DOC: Dissolved organic carbon

DWSRF: Drinking Water State Revolving Fund

EC: Enhanced coagulation

EJ: Environmental justice

EPA: United States Environmental Protection Agency

ESWTR: Enhanced Surface Water Treatment Rule

FACA: Federal Advisory Committee Act

GAC10: Granular activated carbon with ten minute empty bed contact time

and 180 day reactivation frequency

GAC20: Granular activated carbon with twenty minute empty bed contact

time and 180 day reactivation frequency

GDP: Gross Domestic Product

GWR: Groundwater rule

HAA5: Haloacetic acids (five)(chloroacetic acid, dichloroacetic acid,

trichloroacetic acid, bromoacetic acid, and dibromoacetic acid)

HAN: Haloacetonitriles

ICR: Information collection rule (issued under section 1412(b) of the

SDWA)

ILSI: International Life Sciences Institute

IESTWR: Interim Enhanced Surface Water Treatment Rule

LOAEL: Lowest Observed Adverse Effect Level

LT1ESTWR: Long-Term 1Enhanced Surface Water Treatment Rule

MCL: Maximum contaminant level

MCLG: Maximum contaminant level goal

M-DBP: Microbial and Disinfectants/Disinfection Byproducts

mg/L: Milligrams per liter

MRDL: Maximum residual disinfectant level

MRDLG: Maximum residual disinfectant level goal

NDWAC: National Drinking Water Advisory Council

NIST: National Institute of Science and Technology

NOAEL: No Observed Adverse Effect Level

NODA: Notice of Data Availability

NOM: Natural organic matter

NPDWR: National Primary Drinking Water Regulation

NTNCWS: Nontransient noncommunity water system

NTP: National Toxicology Program

NTTAA: National Technology Transfer and Advancement Act

NTU: Nephelometric turbidity unit

OMB: Office of Management and Budget

PAR: Population attributable risk

PBMS: Performance based measurement system

PE: Performance evaluation

PODR: Point of diminishing return

PQL: Practical quantitation limit

PWS: Public water system

QC: Quality control

Reg. Neg.: Regulatory Negotiation

RFA: Regulatory Flexibility Act

RfD: Reference dose

RIA: Regulatory impact analysis

RSC: Relative source contribution

SAB: Science Advisory Board

SBREFA: Small Business Regulatory Enforcement Fairness Act

SDWIS: Safe Drinking Water Information System

SUVA: Specific ultraviolet absorbance

SDWA: Safe Drinking Water Act, or the ``Act,'' as amended 1996

SWTR: Surface Water Treatment Rule

TC: Total coliforms

TCA: Trichloroacetic acid

TCR: Total Coliform Rule

TOC: Total organic carbon

TOX: Total organic halides

TTHM: Total trihalomethanes (chloroform, bromdichloromethane,

dibromochloromethane, and bromoform)

TNCWS: Transient noncommunity water systems

TWG: Technical work group

UMRA: Unfunded mandates reform act

URTH: Unreasonable risk to health

WIDB: Water Industry Data Base



Table of Contents



I. Background

    A. Statutory Requirements and Legal Authority

    B. Regulatory History

    1. Existing Regulations

    2. Public Health Concerns To Be Addressed

    3. Regulatory Negotiation Process

    4. Federal Advisory Committee Process

    5. 1997 and 1998 Notices of Data Availability (NODA)

II. Summary of Final Stage 1 Disinfection Byproduct Rule

    A. Applicability

    B. MRDLGs and MRDLs for Disinfectants

    C. MCLGs and MCLs for TTHMs, HAA5, Chlorite, and Bromate

    D. Treatment Technique for Disinfection Byproducts Precursors

    E. BAT for Disinfectants, TTHMs, HAA5, Chlorite, and Bromate

    F. Compliance Monitoring Requirements

    G. Analytical Methods

    H. Laboratory Certification Criteria

    I. Variances and Exemptions

    J. State Recordkeeping, Primacy, Reporting Requirements

    K. System Reporting Requirements

    L. Guidance Manuals

    M. Regulation Review

III. Explanation of Final Rule

    A. MCLGs/MRDLGs

    1. MCLG for Chloroform

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    2. MCLG for Bromodichloromethane (BDCM)

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    3. MCLG for Dibromochloromethane (DBCM)

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    4. MCLG for Bromoform

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    5. MCLG for Dichloroacetic Acid (DCA)

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    6. MCLG for Trichloroacetic Acid (TCA)

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    7. MCLG for Chlorite and MRDLG for Chlorine Dioxide

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    8. MCLG for Bromate

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments



[[Page 69392]]



    9. MCLG for Chloral Hydrate

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    10. MRDLG for Chlorine

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    11. MRDLG for Chloramine

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    B. Epidemiology

    1. Cancer Epidemiology

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    2. Reproductive and Developmental Epidemiology

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    C. MCLs and BAT for TTHM, HAA5, Chlorite, and Bromate; MRDLs and

BAT for Chlorine, Chloramines, and Chlorine Dioxide

    1. MCLs for TTHMs and HAA5

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    2. MCL for Bromate

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    3. MCL for Chlorite

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    4. MRDL for Chlorine

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    5. MRDL for Chloramines

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    6. MRDL for Chlorine Dioxide

    a. Today's Rule

    b. Background Analysis

    c. Summary of Comments

    D. Treatment Technique Requirement

    1. Today's Rule

    2. Background and Analysis

    3. Summary of Comments

    E. Predisinfection Disinfection Credit

    1. Today's Rule

    2. Background and Analysis

    3. Summary of Comments

    F. Requirements for Systems to Use Qualified Operators

    G. Analytical Methods

    1. Today's Rule

    2. Background and Analysis

    3. Summary of Comments

    4. Performance Based Measurement Systems

    H. Monitoring Requirements

    1. Today's Rule

    2. Background and Analysis

    3. Summary of Comments

    I. Compliance Schedules

    1. Today's Rule

    2. Background and Analysis

    3. Summary of Comments

    J. Public Notice Requirements

    1. Today's Rule

    2. Background and Analysis

    3. Summary of Comments

    K. System Reporting and Record Keeping Requirements

    1. Today's Rule

    2. Summary of Comments

    L. State Recordkeeping, Primacy, and Reporting Requirements

    1. State Recordkeeping Requirements

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    2. Special Primacy Requirements

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    3. State Reporting Requirements

    a. Today's Rule

    b. Background and Analysis

    c. Summary of Comments

    M. Variances and Exemptions

    1. Today's Rule

    2. Background and Analysis

    3. Summary of Comments

    N. Laboratory Certification and Approval

    1. Today's Rule

    2. Background and Analysis

    3. Summary of Comments

IV. Economic Analysis

    A. Today's Rule

    B. Background

    1. Overview of RIA for the Proposed Rule

    2. Factors Affecting Changes to the 1994 RIA

    a. Changes in Rule Criteria

    b. New Information Affecting DBP Occurrence and Compliance

Forecast

    c. New Epidemiology Information

    C. Cost Analysis

    1. Revised Compliance Forecast

    2. System Level Unit Costs

    3. National Costs

    D. Benefits Analysis

    1. Exposure Assessment

    2. Baseline Risk Assessment Based on TTHM Toxicological Data

    3. Baseline Analysis Based on Epidemiology Data

    4. Exposure Reduction Analysis

    5. Monetization of Health Endpoints

    E. Net Benefits Analysis

    F. Summary of Comments

V. Other Requirements

    A. Regulatory Flexibility Analysis

    1. Today's Rule

    2. Background and Analysis

    3. Summary of Comments

    B. Paperwork Reduction Act

    C. Unfunded Mandates Reform Act

    1. Summary of UMRA Requirements

    2. Written Statement for Rules with Federal Mandates of $100

million or More

    a. Authorizing Legislation

    b. Cost Benefit Analysis

    c. Estimates of Future Compliance Costs and Disproportionate

Budgetary Effects

    d. Macro-economic Effects

    e. Summary of State, Local, and Tribal Government and

TheirConcerns

    f. Regulatory Alternative Considered

    3. Impacts on Small Governments

    D. National Technology Transfer and Advancement Act

    E. Executive Order 12866: Regulatory Planning and Review

    F. Executive Order 12898: Environmental Justice

    G. Executive Order 13045: Protection of Children from

Environmental Health Risks and Safety Risks

    H. Consultation with the Science Advisory Board, National

Drinking Water Advisory Council, and the Secretary of Health and

Human Services

    I. Executive Order 12875: Enhancing the Intergovernmental

Partnership

    J. Executive Order 13084: Consultation and Coordination with

Indian Tribal Governments

    K. Submission to Congress and the General Accounting Office

    L. Likely Effect of Compliance with the Stage 1 DBPR on the

Technical, Financial, and Managerial Capacity of Public Water

Systems

VI. References



I. Background



A. Statutory Requirements and Legal Authority



    The Safe Drinking Water Act (SDWA or the Act), as amended in 1986,

requires USEPA to publish a ``maximum contaminant level goal'' (MCLG)

for each contaminant which, in the judgement of the USEPA

Administrator, ``may have any adverse effect on the health of persons

and which is known or anticipated to occur in public water systems''

(Section 1412(b)(3)(A)). MCLGs are to be set at a level at which ``no

known or anticipated adverse effect on the health of persons occur and

which allows an adequate margin of safety'' (Section 1412(b)(4)).

    The Act was amended in August 1996. As a result of these

Amendments, several of these provisions were renumbered and augmented

with additional language. Other sections were added establishing new

drinking water requirements. These modifications are outlined below.

    The Act also requires that at the same time USEPA publishes an

MCLG, which is a non-enforceable health goal, it also must publish a

National Primary Drinking Water Regulation (NPDWR) that specifies

either a maximum contaminant level (MCL) or treatment technique

(Sections 1401(1) and 1412(a)(3)). USEPA is authorized to promulgate a

NPDWR ``that requires the use of a treatment technique in lieu of

establishing a MCL,'' if the Agency finds that ``it is not economically

or technologically feasible to ascertain the level of the

contaminant''.

    As amended, EPA's general authority to set a maximum contaminant

level goal (MCLG) and National Primary Drinking Water Regulation

(NPDWR) applies to contaminants that may ``have an adverse effect on

the health of persons,'' that are ``known to occur or there is a

substantial likelihood that the contaminant will occur in public water



[[Page 69393]]



systems with a frequency and at levels of public health concern,'' and

for which ``in the sole judgement of the Administrator, regulation of

such contaminant presents a meaningful opportunity for health risk

reduction for persons served by public water systems'' (SDWA Section

1412(b)(1)(A)).

    The amendments, also require EPA, when proposing a NPDWR that

includes an MCL or treatment technique, to publish and seek public

comment on an analysis of health risk reduction and cost impacts. In

addition, EPA is required to take into consideration the effects of

contaminants upon sensitive subpopulations (i.e. infants, children,

pregnant women, the elderly, and individuals with a history of serious

illness), and other relevant factors. (Section 1412 (b)(3)(C)).

    The amendments established a number of regulatory deadlines,

including schedules for a Stage 1 Disinfection Byproduct Rule (DBPR),

an Interim Enhanced Surface Water Treatment Rule (IESWTR), a Long-Term

Final Enhanced Surface Water Treatment Rule (LTESWTR) affecting Public

Water Systems (PWSs) that serve under 10,000 people, and a Stage 2 DBPR

(Section 1412(b)(2)(C)). The Act as amended also requires EPA to

promulgate regulations to address filter backwash (Section

1412(b)(14)). Finally, the Act requires EPA to promulgate regulations

specifying criteria for requiring disinfection ``as necessary'' for

ground water systems (Section 1412 (b)(8)).

    Finally, as part of the 1996 SDWA Amendments, recordkeeping

requirements were modified to apply to ``every person who is subject to

a requirement of this title or who is a grantee'' (Section 1445

(a)(1)(A)). Such persons are required to ``establish and maintain such

records, make such reports, conduct such monitoring, and provide such

information as the Administrator may reasonably require by regulation *

* * ''.



B. Regulatory History



1. Existing Regulations

    Surface Water Treatment Rule. Under the Surface Water Treatment

Rule (SWTR) (54 FR 27486, June 29, 1989) (EPA,1989a), EPA set maximum

contaminant level goals of zero for Giardia lamblia, viruses, and

Legionella; and promulgated NPDWR for all PWSs using surface water

sources or ground water sources under the direct influence of surface

water. The SWTR includes treatment technique requirements for filtered

and unfiltered systems that are intended to protect against the adverse

health effects of exposure to Giardia lamblia, viruses, and Legionella,

as well as many other pathogenic organisms. Briefly, those requirements

include: (1) requirements for a maintenance of a disinfectant residual

in the distribution system; (2) removal and/or inactivation of 3 logs

(99.9%) for Giardia and 4 logs (99.99%) for viruses; (3) combined

filter effluent performance of 5 nephelometric turbidity unit (NTU) as

a maximum and 0.5 NTU at 95th percentile monthly, based on 4-hour

monitoring for treatment plants using conventional treatment or direct

filtration (with separate standards for other filtration technologies);

and (4) watershed protection and other requirements for unfiltered

systems.

    Total Coliform Rule. The Total Coliform Rule (TCR) (54 FR 27544;

June 29, 1989) applies to all public water systems (EPA, 1989b). This

regulation sets compliance with the MCL for total coliforms (TC) as

follows. For systems that collect 40 or more samples per month, no more

than 5.0% of the samples may be TC-positive; for those that collect

fewer than 40 samples, no more than one sample may be TC-positive. In

addition, if two consecutive samples in the system are TC-positive, and

one is also fecal coliform or E. coli-positive, then this is defined as

an acute violation of the MCL. If a system exceeds the MCL, it must

notify the public using mandatory language developed by the EPA. The

required monitoring frequency for a system depends on the number of

people served and, ranges from 480 samples per month for the largest

systems to once annually for certain of the smallest systems. All

systems must have a written plan identifying where samples are to be

collected.

    If a system has a TC-positive sample, it must test that sample for

the presence of fecal coliforms or E. coli. The system must also

collect a set of repeat samples, and analyze for TC (and fecal coliform

or E. coli) within 24 hours of the first TC-positive sample.

    The TCR also requires an on-site inspection every 5 years (10 years

for non-community systems using only protected and disinfected ground

water) for each system that collects fewer than five samples per month.

This on-site inspection (referred to as a sanitary survey) must be

performed by the State or by an agent approved by the State.

    Total Trihalomethane Rule. In November 1979 (44 FR 68624) (EPA,

1979) EPA set an interim MCL for total trihalomethanes (TTHM) of 0.10

milligrams per liter (mg/L) as an annual average. Compliance is defined

on the basis of a running annual average of quarterly averages of all

samples. The value for each sample is the sum of the measured

concentrations of chloroform, bromodichloromethane (BDCM),

dibromochloromethane (DBCM) and bromoform.

    The interim TTHM standard only applies to community water systems

using surface water and/or ground water serving at least 10,000 people

that add a disinfectant to the drinking water during any part of the

treatment process. At their discretion, States may extend coverage to

smaller PWSs; however, most States have not exercised this option.

    Information Collection Rule. The Information Collection Rule (ICR)

is a monitoring and data reporting rule that was promulgated on May 14,

1996 (61 FR 24354) (EPA, 1996a). The purpose of the ICR is to collect

occurrence and treatment information to help evaluate the need for

possible changes to the current SWTR and existing microbial treatment

practices, and to help evaluate the need for future regulation for

disinfectants and disinfection byproducts (D/DBPs). The ICR will

provide EPA with additional information on the national occurrence in

drinking water of (1) chemical byproducts that form when disinfectants

used for microbial control react with naturally occurring compounds

already present in source water and (2) disease-causing microorganisms,

including Cryptosporidium, Giardia, and viruses. The ICR will also

provide engineering data on how PWSs currently control for such

contaminants. This information is being collected because the 1992

Regulatory Negotiating Committee (henceforth referred to as the Reg.

Neg. Committee) on microbial pathogens and disinfectants and DBPs

concluded that additional information was needed to assess the

potential health problem created by the presence of DBPs and pathogens

in drinking water and to assess the extent and severity of risk in

order to make sound regulatory and public health decisions. The ICR

will also provide information to support regulatory impact analyses for

various regulatory options, and to help develop monitoring strategies

for cost-effectively implementing regulations.

    The ICR pertains to large public water systems serving populations

at least 100,000; a more limited set of ICR requirements pertain to

ground water systems serving between 50,000 and 100,000 people. About

300 PWSs operating 500 treatment plants are involved with the extensive

ICR data collection. Under the ICR, these PWSs monitor for water

quality factors affecting DBP formation and DBPs



[[Page 69394]]



within the treatment plant and in the distribution system monthly for

18 months. In addition, PWSs must provide operating data and a

description of their treatment plan design and surface water systems

must monitor for bacteria, viruses, and protozoa. Finally, a subset of

PWSs must perform treatment studies, using either granular activated

carbon (GAC) or membrane processes, to evaluate DBP precursor removal

and control of DBPs. Monitoring for treatment study applicability began

in September 1996. The remaining occurrence monitoring began in July

1997.

    One initial intent of the ICR was to collect pathogen occurrence

data and other information for use in developing the IESWTR and to

estimate national costs for various treatment options. However, because

of delays in promulgating the ICR and technical difficulties associated

with laboratory approval and review of facility sampling plans, ICR

monitoring did not begin until July 1, 1997, which was later than

originally anticipated. As a result of this delay and the new statutory

deadlines for promulgating the Stage 1 DBPR and IESWTR in November of

1998 (resulting from the 1996 SDWA amendments), ICR data were not

available in time to support these rules. In place of the ICR data, the

Agency worked with stakeholders to identify other sources of data

developed since 1994 that could be used to support the development of

the Stage 1 DBPR and IESWTR. EPA will continue to work with

stakeholders in analyzing and using the comprehensive ICR data and

research for developing future Enhanced Surface Water Treatment

requirements and the Stage 2 DBPR.

2. Public Health Concerns to be Addressed

    EPA's main mission is the protection of human health and the

environment. When carrying out this mission, EPA must often make

regulatory decisions with less than complete information and with

uncertainties in the available information. EPA believes it is

appropriate and prudent to err on the side of public health protection

when there are indications that exposure to a contaminant may present

risks to public health, rather than take no action until risks are

unequivocally proven.

    In regard to the Stage 1 DBPR, EPA recognizes that the assessment

of public health risks from disinfection of drinking water currently

relies on inherently difficult and preliminary empirical analysis. On

one hand, epidemiologic studies of the populations in various

geographic areas are hampered by difficulties of study design, scope,

and sensitivity. On the other hand, uncertainty is involved in the

interpretation of results using high dose animal toxicological studies

of a few of the numerous byproducts that occur in disinfected drinking

water to estimate the risk to humans from chronic exposure to low doses

of these and other byproducts. Such studies of individual DBPs is

insufficient to characterize risks from exposure to the entire mixture

of DBPs in disinfected drinking water. While recognizing these

uncertainties, EPA continues to believe that the Stage 1 DBPR is

necessary for the protection of public health from exposure to

potentially harmful DBPs.

    A fundamental component in assessing the risk for a contaminant is

the number of people that may be exposed to the parameter of concern.

In this case, there is a very large population potentially exposed to

DBPs through drinking water in the U.S. Over 200 million people are

served by PWSs that apply a disinfectant (e.g., chlorine) to water in

order to provide protection against microbial contaminants. While these

disinfectants are effective in controlling many microorganisms, they

react with natural organic and inorganic matter in the water to form

DBPs, some of which may pose health risks. One of the most complex

questions facing water supply professionals is how to minimize the

risks from DBPs and still maintain adequate control over microbial

contaminants. Because of the large number of people exposed to DBPs,

there is a substantial concern for any risks associated with DBPs that

may impact public health.

    Since the discovery of chlorination byproducts in drinking water in

1974, numerous toxicological studies have been conducted. Results from

these studies have shown several DBPs (e.g., bromodichloromethane,

bromoform, chloroform, dichloroacetic acid, and bromate) to be

carcinogenic in laboratory animals . Some DBPs (e.g., chlorite, BDCM,

and certain haloacetic acids) have also been shown to cause adverse

reproductive or developmental effects in laboratory animals. Although

many of these studies have been conducted at high doses, EPA believes

the studies provide evidence that DBPs present a potential public

health risk that needs to be addressed.

    In the area of epidemiology, a number of epidemiology studies have

been conducted to investigate the relationship between exposure to

chlorinated surface water and cancer. While EPA cannot conclude there

is a causal link between exposure to chlorinated surface water and

cancer, these studies have suggested an association, albeit small,

between bladder, rectal, and colon cancer and exposure to chlorinated

surface water. While there are fewer published epidemiology studies

that have been conducted to evaluate the possible relationship between

exposure to chlorinated surface water and reproductive and

developmental effects, a recent study has suggested an association

between early term miscarriage and exposure to drinking water with

elevated trihalomethane levels. In addition to this study, another new

study reported a small increased risk of neural tube defects associated

with consumption of drinking water containing high levels of TTHMs.

However, no significant associations were observed with individual

THMs, HAAs, and haloacetonitriles (HANs) and adverse outcomes in this

study. As with cancer, EPA cannot conclude at this time there is a

causal link between exposure to DBPs and reproductive and developmental

effects.

    While EPA recognizes there are data deficiencies in the information

on the health effects from the DBPs and the levels at which they occur,

the Agency believes the weight-of-evidence presented by the available

epidemiological studies on chlorinated drinking water and toxicological

studies on individual DBPs support a potential hazard concern and

warrant regulatory action at this time to reduce DBP levels in drinking

water. Recognizing the deficiencies in the existing data, EPA believes

the incremental two-stage approach for regulating DBPs, agreed upon by

the regulatory negotiation process, is prudent and necessary to protect

public health and meet the requirements of the SDWA.

    In conclusion, because of the large number of people exposed to

DBPs and the different potential health risks (e.g., cancer and adverse

reproductive and developmental effects) that may result from exposure

to DBPs, EPA believes the Stage 1 DBPR is needed to further prevent

potential health effects from DBPs, beyond that controlled for by the

1979 total trihalomethane rule. Both the Reg. Neg. Committee for the

1994 proposed rule and the Microbial and Disinfectants/Disinfection

Byproducts Advisory Committee (henceforth cited as the M-DBP Advisory

Committee) formed in March 1997 under the Federal Advisory Committee

Act (FACA), agreed with the need for the Stage 1 DBPR to reduce

potential risks from DBPs in the near term, while acknowledging

additional information is still needed for the Stage 2 DBPR (especially

on health effects),



[[Page 69395]]



3. Regulatory Negotiation Process

    In 1992 EPA initiated a negotiated rulemaking to address public

health concerns associated with disinfectants, DBPs, and microbial

pathogens. The negotiators included representatives of State and local

health and regulatory agencies, public water systems, elected

officials, consumer groups and environmental groups. The Reg. Neg.

Committee met from November 1992 through June 1993.

    Early in the process, the negotiators agreed that large amounts of

information necessary to understand how to optimize the use of

disinfectants to concurrently minimize microbial and DBP risk on a

plant-specific basis were unavailable. Nevertheless, the Reg. Neg.

Committee agreed that EPA propose a Stage 1 DBPR to extend coverage to

all community and nontransient noncommunity water systems that use

disinfectants, reduce the current TTHM MCL, regulate additional DBPs,

set limits for the use of disinfectants, and reduce the level of

organic precursor compounds in the source water that may react with

disinfectants to form DBPs.

    EPA's most significant concern in developing regulations for

disinfectants and DBPs was the need to ensure that adequate treatment

be maintained for controlling risks from microbial pathogens. One of

the major goals addressed by the Reg. Neg. Committee was to develop an

approach that would reduce the level of exposure from disinfectants and

DBPs without undermining the control of microbial pathogens. The

intention was to ensure that drinking water is microbiologically safe

at the limits set for disinfectants and DBPs and that these chemicals

do not pose an unacceptable health risk at these limits. Thus, the Reg.

Neg. Committee also considered a range of microbial issues and agreed

that EPA should also propose a companion microbial rule (IESWTR).

    Following months of intensive discussions and technical analysis,

the Reg. Neg. Committee recommended the development of three sets of

rules: a two-staged approach for the DBPs (proposal: 59 FR 38668, July

29, 1994) (EPA, 1994a), an ``interim'' ESWTR (proposal: 59 FR 38832,

July 29, 1994) (EPA, 1994b), and an information collection rule

(proposal: 59 FR 6332, February 10, 1994) (EPA, 1994c) (promulgation:

61FR24354, May 14, 1996) (EPA, 1996a). The approach used in developing

these proposals considered the constraints of simultaneously treating

water to control for both microbial contaminants and D/DBPs.

    The Reg. Neg. Committee agreed that the schedules for IESWTR and

LTESWTR should be ``linked'' to the schedule for the Stage 1 DBPR to

assure simultaneous compliance and a balanced risk-risk based

implementation. The Reg. Neg. Committee agreed that additional

information on health risk, occurrence, treatment technologies, and

analytical methods needed to be developed in order to better understand

the risk-risk tradeoff, and how to accomplish an overall reduction in

health risks to both pathogens and D/DBPs.

    Finally the Reg. Neg. Committee agreed that to develop a reasonable

set of rules and to understand more fully the limitations of the

current SWTR, additional field data were critical. Thus, a key

component of the regulation negotiation agreement was the promulgation

of the ICR previously described.

4. Federal Advisory Committee Process

    In May 1996, the Agency initiated a series of public informational

meetings to provide an update on the status of the 1994 proposal and to

review new data related to microbial and DBP regulations that had been

developed since July 1994. In August 1996, Congress enacted the 1996

SDWA Amendments which contained a number of new requirements, as

discussed above, as well as specifying deadlines for final promulgation

of the IESWTR and Stage 1 DBPR. To meet these deadlines and to maximize

stakeholder participation, the Agency established the M-DBP Advisory

Committee under FACA in March 1997, to collect, share, and analyze new

information and data, as well as to build consensus on the regulatory

implications of this new information. The Committee consisted of 17

members representing EPA, State and local public health and regulatory

agencies, local elected officials, drinking water suppliers, chemical

and equipment manufacturers, and public interest groups.

    The M-DBP Advisory Committee met five times in March through July

1997 to discuss issues related to the IESWTR and Stage 1 DBPR.

Technical support for these discussions was provided by a Technical

Work Group (TWG) established by the Committee at its first meeting in

March 1997. The Committee's activities resulted in the collection,

development, evaluation, and presentation of substantial new data and

information related to key elements of both proposed rules. The

Committee reached agreement on a number of major issues that were

discussed in Notices of Data Availability (NODA) for the IESWTR (62 FR

59486, November 3, 1997) (EPA, 1997a) and the Stage 1 DBPR (62 FR

59388, November 3, 1997) (EPA, 1997b). The major recommendations

addressed by the Committee and in the NODAs were to: (1) Maintain the

proposed MCLs for TTHM, HAA5, and bromate; (2) modify the enhanced

coagulation requirements as part of DBP control; (3) include a

microbial benchmarking/profiling to provide a methodology and process

by which a PWS and the State, working together, assure that there will

be no significant reduction in microbial protection as the result of

modifying disinfection practices in order to meet MCLs for TTHM and

HAA5; (4) continue credit for compliance with applicable disinfection

requirements for disinfection applied at any point prior to the first

customer, consistent with the existing SWTR; (5) modify the turbidity

performance requirements and add requirements for individual filters;

(6) establish an MCLG for Cryptosporidium; (7) add requirements for

removal of Cryptosporidium; (8) provide for mandatory sanitary surveys;

and (9) make a commitment to additional analysis of the role of

Cryptosporidium inactivation as part of a multiple barrier concept in

the context of a subsequent Federal Register microbial proposal. The

new data and analysis supporting the technical areas of agreement were

summarized and explained at length in EPA's 1997 NODAs (EPA, 1997a and

EPA, 1997b).

5. 1997 and 1998 Notices of Data Availability

    In November 1997 EPA published a NODA (USEPA, 1997b) that

summarized the 1994 proposal; described new data and information that

the Agency has obtained and analyses that have been developed since the

proposal; provided information concerning the July 1997 recommendations

of the M-DBP Advisory Committee on key issues related to the proposal

(described above); and requested comment on these recommendations, as

well as on other regulatory implications that flow from the new data

and information. The Agency solicited additional data and information

that were relevant to the issues discussed in the DBP NODA. EPA also

requested that any information the Agency should consider as part of

the final rule development process regarding data or views submitted to

the Agency since the close of the comment period on the 1994 proposal,

be formally resubmitted during the 90-day



[[Page 69396]]



comment period unless already in the underlying record in the docket

for the NODA.

    In March 1998, EPA issued a second DBP NODA (EPA, 1998a) that

summarized new health effects information received and analyzed since

the November 1997 NODA and requested comments on several issues related

to the simultaneous compliance with the Stage 1 DBPR and the Lead and

Copper Rule. The 1998 NODA indicated EPA was considering increasing the

MCLG for chloroform from zero to 0.3 mg/L and the proposed MCLG for

chlorite from 0.08 mg/L to 0.8 mg/L. EPA also requested comment on

increasing the Maximum Residual Disinfection Level Goal (MRDLG) for

chlorine dioxide from 0.3 mg/L to 0.8 mg/L. Today's final rule was

developed based on the outcome of the 1992 Reg. Neg., the 1994 proposed

rule, the 1997 FACA process, and both the 1997 and 1998 DBP NODAs, as

well as a wide range of technical comments from stakeholders and

members of the public. A summary of today's rule follows.



II. Summary of Final Stage 1 Disinfection Byproduct Rule



A. Applicability



    The final Stage 1 DBPR applies to community water systems (CWSs)

and nontransient noncommunity water systems (NTNCWs) that treat their

water with a chemical disinfectant for either primary or residual

treatment. In addition, certain requirements for chlorine dioxide apply

to transient noncommunity water systems (TNCWSs).



B. MRDLGs and MRDLs for Disinfectants



    EPA is finalizing the following MRDLGs and maximum residual

disinfectant levels (MRDLs) for chlorine, chloramines, and chlorine

dioxide in Table II-1.



                                 Table II-1.--MRDLGs and MRDLs for Disinfectants

----------------------------------------------------------------------------------------------------------------

          Disinfectant residual                      MRDLG (mg/L)                         MRDL (mg/L)

----------------------------------------------------------------------------------------------------------------

Chlorine................................  4 (as Cl<INF>2)                          4.0 (as Cl<INF>2)

Chloramine..............................  4 (as Cl<INF>2)                          4.0 (as Cl<INF>2)

Chlorine Dioxide........................  0.8 (as ClO<INF>2)                       0.8 (as ClO<INF>2)

----------------------------------------------------------------------------------------------------------------



C. MCLGs and MCLs for TTHMs, HAA5, Chlorite, and Bromate



    EPA is finalizing the MCLGs and MCLs in Table II-2.



         Table II-2.--MCLGs and MCLs for Disinfection Byproducts

------------------------------------------------------------------------

           Disinfection byproducts             MCLG (mg/L)   MCL (mg/L)

------------------------------------------------------------------------

Total trihalomethanes (TTHM) \1\............        N/A            0.080

    --Chloroform............................          0     ............

    --Bromodichloromethane..................          0     ............

    --Dibromochloromethane..................          0.06  ............

    --Bromoform.............................          0     ............

Haloacetic acids (five) (HAA5) \2\..........        N/A            0.060

    --Dichloroacetic acid...................          0     ............

    --Trichloroacetic acid..................          0.3   ............

Chlorite....................................          0.8          1.0

Bromate.....................................          0            0.010

------------------------------------------------------------------------

N/A--Not applicable because there are no individual MCLGs for TTHMs or

  HAAs.

\1\ Total trihalomethanes is the sum of the concentrations of

  chloroform, bromodichloromethane, dibromochloromethane, and bromoform.

\2\ Haloacetic acids (five) is the sum of the concentrations of mono-,

  di-, and trichloroacetic acids and mono- and dibromoacetic acids.



D. Treatment Technique for Disinfection Byproduct Precursors



    Water systems that use surface water or ground water under the

direct influence of surface water and use conventional filtration

treatment are required to remove specified percentages of organic

materials (measured as total organic carbon) that may react with

disinfectants to form DBPs as indicated in Table II-3. Removal will be

achieved through a treatment technique (enhanced coagulation or

enhanced softening) unless a system meets alternative criteria

discussed in Section III.D.



    Table II-3.--Required Removal of Total Organic Carbon by Enhanced

     Coagulation and Enhanced Softening for Subpart H Systems Using

                     Conventional Treatment <SUP>a,\<SUP>b,\<SUP>c

------------------------------------------------------------------------

                                      Source Water Alkalinity (mg/L as

                                              CaCO<INF>3) (percent)

     Source Water TOC (mg/L)      --------------------------------------

                                       0-60       >60-120        >120

------------------------------------------------------------------------

>2.0-4.0.........................         35.0         25.0         15.0

>4.0-8.0.........................         45.0         35.0         25.0



[[Page 69397]]





>8.0.............................         50.0         40.0         30.0

------------------------------------------------------------------------

<SUP>a Systems meeting at least one of the conditions in Section

  141.135(a)(2) (i)-(vi) of the rule are not required to operate the

  removals in this table.

<SUP>b Softening systems meeting one of the two alternative compliance

  criteria in Section 141.135(a)(3) of the rule are not required to meet

  the removals in this table.

<SUP>c Systems practicing softening must meet the TOC removal requirements in

  the last column to the right.



E. BAT for Disinfectants, TTHMs, HAA5, Chlorite, and Bromate



    Under the SDWA, EPA must specify the BAT for each MCL (or MRDL)

that is set. PWS that are unable to achieve an MCL or MRDL may be

granted a variance if they use the BAT and meet other requirements (see

section III.M for a discussion of variances and exemptions). Table II.4

includes the BATs for each of the MCLs or MRDLs that EPA is

promulgating in today's Stage 1 DBPR.



     Table II-4.--BAT for Disinfectants and Disinfection Byproducts

------------------------------------------------------------------------

       Disinfectant/DBP                Best available technology

------------------------------------------------------------------------

                              Disinfectants



------------------------------------------------------------------------

Chlorine residual............  Control of treatment processes to reduce

                                disinfectant demand and control of

                                disinfection treatment processes to

                                reduce disinfectant levels.

Chloramine residual..........  Control of treatment processes to reduce

                                disinfectant demand and control of

                                disinfection treatment processes to

                                reduce disinfectant levels.

Chlorine dioxide residual....  Control of treatment processes to reduce

                                disinfectant demand and control of

                                disinfection treatment processes to

                                reduce disinfectant levels.



------------------------------------------------------------------------

                         Disinfection Byproducts



------------------------------------------------------------------------

Total trihalomethanes........  Enhanced coagulation or enhanced

                                softening or GAC10*, with chlorine as

                                the primary and residual disinfectant.

Total haloacetic acids.......  Enhanced coagulation or enhanced

                                softening or GAC10*, with chlorine as

                                the primary and residual disinfectant.

Chlorite.....................  Control of treatment processes to reduce

                                disinfectant demand and control of

                                disinfection treatment processes to

                                reduce disinfectant levels.

Bromate......................  Control of ozone treatment process to

                                reduce production of bromate.

------------------------------------------------------------------------

* GAC10 means granular activated carbon with an empty bed contact time

  of 10 minutes and reactivation frequency for GAC of no more than six

  months.



F. Compliance Monitoring Requirements



    Compliance monitoring requirements are explained in Section III.H

of today's rule. EPA has developed routine and reduced compliance

monitoring schemes for disinfectants and DBPs to be protective from

different types of health concerns, including acute and long-term

effects.



G. Analytical Methods



    EPA has approved five methods for measurement of free chlorine,

four methods for combined chlorine, and six for total chlorine. EPA has

also approved two methods for the measurement of chlorine dioxide

residuals; three methods for the measurement of HAA5; three methods for

the measurement of TTHMs; three methods for the measurement of TOC/

Dissolved Organic Carbon (DOC); two methods for the monthly measurement

of chlorite and one method for the daily monitoring of chlorite; two

methods for bromide; one method for the measurement of bromate; and one

method for the measurement of UV<INF>254</INF>. Finally, EPA approved

all methods allowed in Sec. 141.89(a) for measuring alkalinity. These

issues are discussed in more detail in section III.G.



H. Laboratory Certification Criteria



    Consistent with other drinking water regulations, determinations of

compliance with the MCLs may only be conducted by certified

laboratories. EPA is requiring that analyses can be conducted by a

party acceptable to EPA or the State in those situations where the

parameter can adequately be measured by someone other than a certified

laboratory and for which there is a good reason to allow analysis at

other locations (e.g., for samples which normally deteriorate before

reaching a certified laboratory, especially when taken at remote

locations). For a detailed discussion of the lab certification

requirements, see section III.N.



I. Variances and Exemptions



    Variances and exemptions will be permitted in accordance with

existing statutory and regulatory authority. For a detailed discussion

see section III.M.



J. State Recordkeeping, Primacy, and Reporting Requirements



    The Stage 1 DBPR requires States to adopt several regulatory

requirements, including public notification requirements, MCLs for

DBPs, MRDLs for disinfectants, and the requirements in Subpart L. In

addition, States are required to adopt several special primacy

requirements for the Stage 1 DPBR. States are also required to keep

specific records in accordance with existing regulations and additional

records specific to the Stage 1 DBPR. Finally, the rule does not

require any



[[Page 69398]]



State additional reporting requirements beyond those required under

existing regulations. These requirements are discussed in more detail

in Section III.L.



K. System Reporting Requirements



    System are required to report monitoring data to the State as

discussed in Section III.K.



L. Guidance Manuals



    EPA is developing guidance for both systems and States for the

implementation of the Stage 1 DBPR and the IESWTR. The guidance manuals

include: Guidance Manual for Enhanced Coagulation and Precipitative

Softening; Disinfection Benchmark Guidance Manual; Turbidity Guidance

Manual; Alternative Disinfectants and Oxidants Guidance Manual; M/DBP

Simultaneous Compliance Manual; Sanitary Survey Guidance Manual;

Unfiltered Systems Guidance Manual; and Uncovered Finished Water

Reservoirs. Guidance manuals will be available after the publication of

the Stage 1 DBPR.



M. Regulation Review



    Under the provisions of the SDWA (Section 1412(b)(9)), the Agency

is required to review NPDWRs at least once every six years. As

mentioned previously, today's final rule revises, updates, and

supersedes the regulations for total trihalomethanes, initially

published in 1979. Since that time, there have been significant changes

in technology, treatment techniques, and other regulatory controls that

provide for greater protection of human health. As such, for today's

rule, EPA has analyzed innovations and changes in technology and

treatment techniques that have occurred since promulgation of the

interim TTHM regulations. That analysis, contained primarily in the

cost and technology document supporting this rule, supports the changes

in the Stage 1 DBPR from the 1979 TTHM rule. EPA believes that the

innovations and changes in technology and treatment techniques that

result in changes to the 1979 TTHM regulations are feasible within the

meaning of SDWA Section 1412(b).



III. Explanation of Final Rule



A. MCLGs/MRDLGs



    MCLGs are set at levels at which no known or anticipated adverse

health effects occur, allowing for an adequate margin of safety.

Establishment of an MCLG for each specific contaminant is based on the

available evidence of carcinogenicity or noncancer adverse health

effects from drinking water exposure using EPA's guidelines for risk

assessment (see the proposed rule at 59 FR 38677 for a detailed

discussion of the process for establishing MCLGs).

    The final Stage 1 DBPR contains MCLGs for: four THMs (chloroform,

bromodichloromethane, dibromochloromethane, and bromoform); two

haloacetic acids (dichloroacetic acid and trichloroacetic acid);

bromate; and chlorite (see table II-2 for final MCLG levels). These

MCLGs are the same as those proposed in 1994 with the exception of

chlorite, which increased from 0.08 mg/L to 0.8 mg/L. The MCLG for

chloral hydrate has been dropped since EPA has concluded that it will

be controlled by the MCLs for TTHM and HAA5 and the enhanced

coagulation treatment technique.

    The final Stage 1 DBPR contains MRDLGs for chlorine, chloramines

and chlorine dioxide (see table II-1 for final MRDLG levels). The

MRDLGs are as the same as those proposed in 1994, with the exception of

chlorine dioxide, which increased from 0.3 mg/L to 0.8 mg/L.

    The MRDLG concept was introduced in the proposed rule for

disinfectants to reflect the fact that these substances have beneficial

disinfection properties. As with MCLGs, MRDLGs are established at the

level at which no known or anticipated adverse effects on the health of

persons occur and which allows an adequate margin of safety. MRDLGs are

nonenforceable health goals based only on health effects and exposure

information and do not reflect the benefit of the addition of the

chemical for control for waterborne microbial contaminants. By using

the term ``residual disinfectant'' in lieu of ``contaminant'', EPA

intends to avoid situations in which treatment plant operators are

reluctant to apply disinfectant dosages above the MRDLG during short

periods of time to control for microbial risk.

    EPA received numerous comments on the use of the term MRDLG. The

majority of commenters agreed that the term MRDLG was appropriate to

use in place of MCLG for disinfectants. Other commenters agreed, but

felt that the language should more strongly reflect that disinfectants

are necessary and that short-term exposure to elevated levels of the

disinfectants is not a health concern. Some commenters suggested that

MRDLGs be extended to ozone, potassium permanganate and iodine.

    In response, EPA agrees with the majority of commenters that the

use of the term MRDLG is appropriate and therefore the final rule

retains this term. EPA believes the language on the importance of

disinfectants is adequate in the rule and thus has not changed this

language. EPA does not agree that the potential health effects from

short-term exposure to elevated levels of disinfectants can be

dismissed. Ozone does not require an MRDLG because it reacts so

completely that it does not occur in water delivered to consumers.

Finally, EPA believes the use of the MRDLGs for other disinfectants or

oxidants would not be appropriate since MRDLGs are developed for

regulated compounds controlled by MRDLs or treatment techniques and EPA

does not allow these compounds to be used to demonstrate compliance

with disinfection requirements.

    The information EPA relied on to establish the MCLGs and MRDLGs was

described in the 1994 proposal (EPA, 1994a), the 1997 DBP NODA (EPA,

1997b), and the 1998 NODA (EPA, 1998a). Criteria and assessment

documents to support the MCLGs and MRDLGs are included in the docket

(EPA, 1993a; EPA, 1994 d-h; EPA, 1997c; EPA, 1998 b-f; and EPA, 1998p).

A summary of the occurrence and exposure information for this rule are

detailed in ``Occurrence Assessment for Disinfectants and Disinfection

Byproducts in Public Drinking Water Supplies' (EPA, 1998u). The

discussion of the data used to establish the MCLGs and MRDLGs and a

summary of the major public comments for these chemicals are included

below. A more detailed discussion is included below for chloroform,

DCA, chlorite, chloride dioxide, and bromate than the other

disinfectants and DBPs. This is the case because significant new data

has become available since the 1994 proposal for these four DBPs and

one disinfectant.

1. MCLG for Chloroform

    a. Today's Rule. After careful consideration of all public

comments, EPA has concluded at this time to promulgate an MCLG for

chloroform of zero as proposed. This conclusion reflects an interim

risk-management decision on the part of the Agency. The Agency

recognizes the strength of the science in support of a non-linear

approach for estimating carcinogenicity of chloroform. EPA received

public comments that questioned the underlying basis and approach used

to reach the science judgment that the mode of chloroform's

carcinogenic action supports a nonlinear approach. Equally important

are the policy and regulatory issues raised by stakeholders that touch

on this issue. EPA believes that it is essential to pursue a further

dialogue with stakeholders on the issues raised in the public comments

before applying the substantial new data and science on the mode of

carcinogenic



[[Page 69399]]



action discussed in the 1998 NODA to the important decision of moving

to a non-linear cancer extrapolation approach for drinking water

contaminants under the SDWA. Moreover, EPA will complete additional

deliberations with the Agency's Science Advisory Board (SAB) (open to

stakeholder presentations to the SAB) on the analytical approach used

to evaluate and reach conclusions on mode of action data, and the

science basis for the mode of carcinogenic action for chloroform.

    In evaluating how to proceed in the development of an MCLG for

chloroform, the Agency believes two additional factors must be taken

into consideration. First, as part of the 1996 SDWA amendments,

Congress mandated that the Stage 1 DBPR rule be promulgated by November

1998. EPA has concluded that it would be impossible to complete the

additional deliberations noted above in time to meet this statutory

deadline. Second, as explained below, the Agency has also completed

analysis indicating that regardless of whether the MCLG is based on a

low-dose linear or non-linear extrapolation approach, the MCL

enforceable standard for TTHMs of 0.08 mg/L will not be affected. In

light of these issues, EPA believes it is appropriate and consistent

with the public health goals of the SDWA to establish a zero MCLG for

chloroform based on a linear default extrapolation approach until the

Agency is able to complete additional deliberations with the Agency's

SAB on the analytical approach used to evaluate and reach conclusions

on mode of action data and the science basis for the mode of

carcinogenic action for chloroform, and complete the process of further

public dialogue on the important question of moving to a non-linear

cancer extrapolation approach. EPA also notes that its approach is

consistent with legislative history of the SDWA (see 56 FR 3533--EPA,

1991) and the 1996 SDWA Amendments.

    b. Background and Analysis. As part of its 1994 Stage 1 DBP

proposal (EPA, 1994a), EPA requested comment on a zero MCLG for

chloroform. This was consistent with information provided to the 1992

Reg. Neg. Committee and was based on data from a drinking water study

by Jorgensen et al. (1985) indicating an increase of kidney tumors in

male rats in a dose-related manner. However, at the time of the

proposal there was insufficient data to determine the mode of

carcinogenic action for chloroform. Therefore, EPA based its 1994

proposal on a risk management decision that a presumptive or low-dose

linear default (i.e, MCLG of zero) was appropriate until more research

became available and there was an adequate opportunity to work with

stakeholders and the scientific community to evaluate and assess the

technical as well as policy and regulatory implications of such new

information. The 1994 proposal also reflected the Agency's 1986

Guidelines for Carcinogen Risk Assessment (EPA, 1986) which recommended

reliance on the default assumption of low-dose linearity in the absence

of substantial information on the mechanism of carcinogenicity.

    Since the 1994 proposal, over 30 toxicological studies have been

published on chloroform. These studies were discussed in the November

1997 Stage 1 DBP NODA (EPA, 1997b). In addition, EPA published a second

DBP NODA in March 1998 (EPA, 1998a) which discussed recommendations and

findings from a 1997 International Life Sciences Institute project

(ILSI, 1997), co-sponsored by EPA, on the cancer assessment for

chloroform. The ILSI project included the analysis and conclusions from

an expert panel which was convened and charged with reviewing the

available database relevant to the carcinogenicity of chloroform, and

considering how end points related to mode of action can be applied in

hazard and dose-response assessment by using guidance provided by the

EPA's 1996 Proposed Guidelines for Carcinogen Assessment (EPA, 1996b).

The panel was made up of 10 internationally recognized scientists from

academia, industry, government, and the private sector. Based on a

consideration of the ILSI panel findings and an assessment of new data

on chloroform since 1994, EPA requested comment in the 1998 NODA on the

Agency's science conclusion that chloroform is a likely human

carcinogen and that available scientific analysis supports a non-linear

mode of action for estimating the carcinogenic risk associated with

lifetime exposure from ingesting drinking water.

    As part of the 1998 NODA, EPA also requested comment on a revised

chloroform MCLG of 0.30 mg/L. The revised MCLG was premised on the

substantial new science noted above that supports a non-linear mode of

action. In calculating the specific MCLG, EPA relied upon data relating

to hepatoxicity in dogs (EPA, 1994a). This hepatoxicity endpoint was

deemed appropriate given that hepatic injury is the primary effect

following chloroform exposure; and that an MCLG based on protection

against liver toxicity should be protective against carcinogenicity

given that the putative mode of action understanding for chloroform

involves cytotoxicity as a key event preceding tumor development. The

MCLG of 0.3 mg/L was calculated using a relative source contribution

(RSC) of 80 percent. The RSC of 80 percent was based on the assumption

that most exposure to chloroform is likely to come from ingestion of

drinking water. The 80 percent assumption for the RSC was consistent

with the calculations used to derive the MCLGs for D/DBPs in the 1994

proposal. Based on information received during the public comment

period for the 1998 NODA, EPA is considering revising its estimate of

the RSC for chloroform as discussed below.

    Since the 1998 NODA, EPA has reevaluated elements of the analysis

underlying a revised MCLG of 0.30 mg/L. Considering recent information

not fully analyzed as part of the 1998 NODA, the Agency is considering

revising the assumption of an 80% RSC from ingestion of drinking water

in view of data which indicates that exposure to chloroform via

inhalation and dermal exposure may potentially contribute a substantial

percentage of the overall exposure to chloroform depending on the

activity patterns of individuals. Also, EPA is in the process of

developing a policy for incorporating inhalation and dermal exposure

into the derivation of the RSC. Furthermore, there is considerable

uncertainty regarding the potential exposure to chloroform via the

dietary route and there is information which indicates individuals who

are frequent swimmers may receive a large amount of chloroform during

swimming. There are additional uncertainties regarding other possible

highly exposed sub-populations, e.g., from use of humidifiers, hot-

tubs, and outdoor misters. In conclusion, because there may be a

potential for exposure to chloroform from other routes of exposure than

ingestion of drinking water, EPA is considering using the 20 percent

default floor to ensure adequate public health protection. The 20

percent has been used historically for drinking water contaminants

other than D/DBPs when there is uncertainty in the available exposure

data. The use of the 20 percent RSC for chloroform would produce a MCLG

of 0.07 mg/L:



[[Page 69400]]



[GRAPHIC] [TIFF OMITTED] TR16DE98.000





    In addition to its reassessment of technical assumptions underlying

the revised MCLG, the Agency has also reviewed and carefully considered

in detail a number of significant comments on the 1998 NODA. These

comments reflect both substantial scientific support as well as

significant concerns with a possible MCLG of 0.30 mg/L. As outlined in

more detail below, a number of nationally recognized scientific experts

strongly affirmed the data and technical rationale for relying upon a

non-linear mode of action for chloroform. Other commenters, however,

highlighted several scientific issues they felt were not adequately

considered. These commenters also emphasized their concern that the

policy, regulatory, and enforcement implications related to a revised

MCLG were not raised by EPA in either the 1992 or the 1997 regulatory

negotiation processes leading up to today's final rule. Thus, these

commenters felt that a number of stakeholders who recommended support

for components of the Stage 1 DBPR rule did so under one set of

conditions and assumptions that the Agency subsequently changed without

providing a sufficient opportunity for further debate and discussion.

    EPA believes that an adequate opportunity for notice and comment

was provided as a result of the 1997 and 1998 DBP NODAs on the

underlying scientific data and technical issue of moving to a non-

linear extrapolation approach based on an understanding of the mode of

carcinogenic action for chloroform and recalculating the chloroform

MCLG to a nonzero number. However, the Agency recognizes that reliance

on a non-linear mode of action under the SDWA does represent a

significant and precedential, albeit sound, application of new science

to the policy development and risk management decision making process

of establishing appropriately protective MCLGs. The Agency also

recognizes that although, as discussed below, a revised MCLG for

chloroform would not affect the TTHM MCL under today's rule, the

precedential decision to utilize a non-linear cancer extrapolation

approach clearly has important implications for the development of

future MCLGs where there is also adequate scientific research and data

to support such a non-linear analysis.

    In reviewing the range of scientific, policy, and regulatory

analyses and strongly held views associated with development of the

chloroform MCLG, EPA notes that the one question not fundamentally at

issue is the establishment of the 0.080 mg/L TTHM MCL. The majority of

commenters who addressed the proposed TTHM MCL continue to support it.

This is particularly important to EPA in light of congressional action

with regard to the M-DBP process in the 1996 SDWA Amendments. In

enacting the Amendments and particularly in expressing congressional

intent in the conference Report, Congress was careful to emphasize

``that the new provisions of this conference agreement not conflict

with the parties' agreement nor disrupt the implementation of the

regulatory actions,'' (such as the current agreement on an TTHM MCL of

0.080 mg/L). Both of these important elements of the Congressional

intent were reflected in the statutory text. Section 1412(b)(2)(C)

requires EPA to maintain the M-DBP rule staggered promulgation strategy

agreed to by the negotiated rulemaking; and Section 1412(b)(6)(C)

exempted the future M-DBP rules from the new cost-benefit standard-

setting provision (1412(b)(6)(A)) but not from the new risk-risk

provision (1412(b)(5)), because the latter was a part of the negotiated

rulemaking agreement but the former was not.

    The Agency, itself, also believes that the underlying logic, data,

and rationale supporting establishment of a TTHM of 0.080 mg/L MCL is

compelling, and this is a critical factor in the Agency's chloroform

MCLG decision under today's rule. Under either a low-dose linear or

non-linear extrapolation to derive the MCLG, the final TTHM MCL remains

unaffected.

    After thorough review of the data and comments, EPA believes the

nonlinear cancer extrapolation approach is the most appropriate means

to establish an MCLG for chloroform based on carcinogenic risk.

However, in light of its own reconsideration of the appropriate RSC for

chloroform under such an approach, considering the range of policy,

regulatory, and enforcement issues raised as part of the public comment

period, recognizing the importance of deliberations with SAB before

proceeding further and, yet, recognizing that this cannot be

accomplished within the constraints of meeting the statutory deadline

for Stage 1 DBPR rule of November 1998, EPA has determined that on

balance the more appropriate and prudent risk management decision at

this time is to establish an MCLG for chloroform at the proposed

presumptive default level of zero. As part of this decision, the Agency

will complete additional deliberations with the Agency's SAB on the

analytical approach used to evaluate and reach conclusions on mode of

action data, and the science basis for the mode of carcinogenic action

for chloroform. The SAB's review will be factored into the Agency's

Stage 2 DBP rulemaking process. EPA will also include consideration of

the regulatory, policy, and precedential issues involving chloroform in

the Agency's Round 2 M-BP stakeholder process. EPA wishes to make clear

that its interim decision in today's rule to set an MCLG of zero

pending SAB review and further stakeholder involvement is not intended

to prejudge the question of what the appropriate MCLG should be for

purposes of regulatory decisions under the Stage 2 DBPR. EPA may decide

to retain the zero MCLG for that rule, or to revise it, depending on

the outcome of the SAB review, as well as any new scientific evidence

that may become available. In regard to the appropriate RSC factor, in

case a non-linear approach should ultimately be adopted, the Agency

requests that stakeholders provide any data they man have bearing on

this determination.

    The fundamental objective of the SDWA is to establish protective

public health goals (MCLGs) together with enforceable standards (MCLs

or treatment techniques) to move the water treatment systems as close

to the public health goal as is technologically and economically

feasible. In the case of the chloroform and TTHMs, this objective is

met with whichever extrapolation approach (low dose linear versus

nonlinear) is relied upon.

    c. Summary of Comments. EPA received numerous comments on both the

1994 proposed rule regarding the MCLG of zero for chloroform and the

MCLG of 0.3 mg/L contained in the 1998 NODA. Some commenters were

supportive of the MCLG of zero, while others were supportive of the 0.3

mg/L MCLG. The major reason raised by commenters for establishing a

nonzero MCLG (e.g., 0.3 mg/L) was that there was convincing scientific

evidence to conclude that a nonlinear margin of exposure approach for

evaluating the carcinogenic risk from chloroform is warranted.

Commenters who were



[[Page 69401]]



against establishing a nonzero MCLG for chloroform presented policy and

scientific concerns. Scientific concerns raised by commenters opposed

to the nonzero MCLG included their perceptions that: there is

insufficient scientific evidence of a threshold for chloroform; the

threshold assumption is also invalid because chloroform co-occurs with

other mutagenic carcinogens; EPA ignored human data in establishing the

MCLG for chloroform; the linkage between cytotoxicity and regenerative

proliferation and kidney tumors is not supported by the data; and the

evidence for genotoxicity is mixed and it would be difficult if not

impossible to conclude that the evidence demonstrate chloroform has no

direct effect on DNA. As detailed at greater length in the docket, EPA

does not agree with these comments as a technical matter. The Agency

does agree with the commenters view that further discussion of these

issues with both the SAB and as part of additional public dialogue is

appropriate.

    The policy issues raised by commenters included their belief that:

a zero MCLG is required to comply with provisions of the SDWA; EPA is

required to use the 1986 Cancer Guidelines (EPA, 1986) until the 1996

Cancer Guidelines (EPA, 1996b) are formally finalized, and under the

1986 guidelines the MCLG for chloroform must be set at zero; EPA did

not provide sufficient opportunity for the members of the FACA,

established to assist in the development of the Stage 1 DBP rule, to

properly consider the potential implications of a nonzero MCLG; and

setting a MCLG for chloroform (0.3 mg/L) above the MCL for the TTHMs

(0.08 mg/L) is illogical.

    In response, EPA believes that the underlying science for using a

nonlinear extrapolation approach to evaluate the carcinogenic risk from

chloroform is well founded. As explained above, because of the issues

raised during the public comment period, EPA believes additional review

and dialogue with stakeholders is needed prior to departing from a

long-held EPA policy of establishing zero MCLGs for known or probable

carcinogens. EPA will also complete additional deliberations with the

Agency's SAB on the analytical approach used to evaluate and reach

conclusions on mode of action data, and the science basis for the mode

of carcinogenic action for chloroform.

    In response to the policy issues raised by commenters, EPA,

historically, has established MCLGs of zero for known or probable human

carcinogens based on the principle that any exposure to carcinogens

might represent some finite level of risk and therefore an MCLG above

zero did not meet the statutory requirement that the goal be set where

no known anticipated adverse effects occur, allowing for an adequate

margin of safety (56 FR 3533; EPA, 1991). However, if there is

scientific evidence that indicates there is a ``safe threshold'' then a

non-zero MCLG could be established with an adequate margin of safety

(56 FR 3533; EPA, 1991)). Even though EPA, as an interim matter, is

establishing an MCLG of zero for chloroform in today's rule, it

believes it has the authority to establish nonzero MCLGs for

carcinogens if the scientific evidence supports this finding.

    In response to commenter's concerns with EPA using the proposed

1996 Guidelines for Carcinogen Risk Assessment (EPA, 1996b) instead of

the Agency's 1986 guidelines, EPA believes it is important to point out

that the 1986 guidelines provide for departures from default

assumptions such as low dose linear assessment. For example, the 1986

EPA guidelines reflect the position of the OSTP (1985; Principle 26)

``No single mathematical procedure is recognized as the most

appropriate for low-dose extrapolation in carcinogenesis. When relevant

biological evidence on mechanisms of action exists (e.g,

pharmacokinetics, target organ dose), the models or procedure employed

should be consistent with the evidence.'' The 1986 guideline goes on to

further state ``The Agency will review each assessment as to the

evidence on carcinogenesis mechanisms and other biological or

statistical evidence that indicates the suitability of a particular

extrapolation model.'' The EPA's 1996 Proposed Guidelines for

Carcinogen Risk Assessment allow EPA to use other default approaches to

estimate cancer risk than the historic, linearized multistage default

when there is an understanding of an agent's mode of carcinogenic

action. EPA believes that reliance on the 1986 guidance allows EPA to

reach the same conclusion on the carcinogenic risk from chloroform as

if the 1996 guidelines were used. The use of the best available science

is a core EPA principle and is statutorily mandated by the SDWA

amendments of 1996. The 1996 Proposed Guidelines for Carcinogen Risk

Assessment reflect new science and are consistent with the existing

1986 Guidelines for Carcinogen Risk Assessment. EPA considered the 1996

proposed guidelines in assessing the health effects data for chloroform

and the other contaminants discussed in the 1998 March NODA.

    EPA agrees with commenters that additional review by the FACA of

the regulatory implications of a nonlinear approach is appropriate for

policy reasons, and will initiate these discussions in the context of

the Stage 2 DBPR FACA deliberations. In light of the November 1998

statutory deadline to promulgate the Stage 1 DBP rule and the steps

necessary to complete a final rule, EPA has concluded that there is not

enough time to meet with the SAB and FACA, provide ample opportunity

for debate, resolve differing points of views, and complete additional

analysis to meet stakeholders policy concerns in the context of the

Stage 1 DBP rule. EPA notes, however, that regardless of the MCLG for

chloroform, the MCL for the THMs remains at 0.08 mg/L. Since the MCL is

the enforceable standard that water systems will be required to meet, a

nonlinear or low dose linear extrapolation to derive the MCLG will not

have a direct impact on the compliance obligations of public water

systems or on the levels of chloroform allowed in public water systems,

although it may be relevant to development of enforceable regulatory

limits established under future rules.

2. MCLG for Bromodichloromethane (BDCM)

    a. Today's Rule. The final MCLG for BDCM is zero. The zero MCLG is

based on the classification of BDCM as a probable human carcinogen. The

MCLG was determined in a weight-of-evidence evaluation which considered

all relevant health data including carcinogenicity and reproductive and

developmental toxicity animal data. EPA believes the data are

insufficient at this time to determine the mode of carcinogenic action

for BDCM, and therefore a low dose linear extrapolation approach is

used to estimate lifetime cancer risk as a default.

    b. Background and Analysis. In the 1994 Stage 1 DBPR proposal, the

MCLG of zero for BDCM was based on large intestine and kidney tumor

data from a National Toxicology Program (NTP) chronic animal study

(NTP, 1987). Since the proposal, several new studies have been

published on BDCM metabolism (EPA, 1997c). In addition, several new

genotoxicity studies and short-term toxicity studies including

reproductive evaluations were found for BDCM (EPA, 1997c). These new

studies contribute to the weight-of-evidence conclusions reached in the

1994 proposal. Based on this evidence, the final MCLG for BDCM is zero

based on sufficient evidence of carcinogenicity in animals.

    c. Summary of Comments. Several commenters disagreed with the use

of a



[[Page 69402]]



corn oil gavage animal cancer study to determine the MCLG for BDCM.

Some commenters agreed with the EPA decision to use large intestine and

kidney tumor data from the corn oil gavage study, but not liver tumor

data in the quantitative estimation of carcinogenic risk. One commenter

agreed that a low-dose linear extrapolation approach to dose-response

assessment was appropriate at this time and consistent with EPA policy.

However, this commenter suggested that EPA undertake chronic studies

that include a drinking water study of BDCM and toxicokinetics. One

commenter disagreed with the EPA conclusion that the evidence on the

mutagenicity of BDCM is adequate.

    In response, EPA agrees with commenters that a drinking water study

is preferable to a corn oil gavage study to assess risk from DBPs in

drinking water. However, the NTP corn oil gavage study is the best data

available on BDCM for a quantitative risk estimation at this time. BDCM

is currently being tested for toxicokinetics and cancer in a chronic

BDCM drinking water rodent study by the NTP. When these data are

available, EPA will reassess the cancer risk of BDCM. EPA believes that

the animal data currently available on BDCM are consistent with EPA

cancer guidelines on classifying BDCM as a probable human carcinogen

given the evidence on mutagenicity and given there was an increased

incidence of tumors at several sites in the animals. Additionally,

tumors were found in both sexes of two rodent species. Finally, there

have been several new studies on the genotoxicity of BDCM that have

supported a mutagenic potential for BDCM (EPA, 1997c)

3. MCLG for Dibromochloromethane (DBCM)

    a. Today's Rule. The final MCLG for DBCM is 0.06 mg/L. This MCLG is

based on a weight of evidence evaluation of the cancer and noncancer

data which resulted in the classification of DBCM as a possible human

carcinogen.

    b. Background and Analysis. In the 1994 proposal, the MCLG of 0.06

mg/L for DBCM was based on observed liver toxicity from a subchronic

study and possible carcinogenicity (NTP, 1985). EPA is not aware of any

new information that would change its evaluation of DBCM since the

proposal. The final MCLG is therefore 0.06 mg/L.

    c. Summary of Comments. Several commenters disagreed with the

additional safety factor of 10 to account for possible carcinogenicity

that was used in the MCLG calculation. One commenter agreed with EPA's

decision to base the MCLG on noncarcinogenic endpoints. Several

commenters disagreed with the use of a corn oil gavage study to

determine the MCLG for DBCM.

    In response, because the evidence of carcinogenicity was limited on

DBCM (i.e., increased tumor response in only one of the two species

tested), EPA classified DBCM as a possible human carcinogen. The

additional factor of 10 to account for possible carcinogenicity follows

EPA's science policy for establishing MCLGs (EPA, 1994a). EPA used

liver effects from the NTP subchronic corn oil gavage study as the

basis for the Reference Dose (RfD). EPA agrees with the comment that

this is an appropriate basis for deriving the RfD for DBCM. EPA agrees

with commenters that a drinking water study is preferable to a corn oil

gavage study to assess risk from DBPs in drinking water. However, the

NTP corn oil gavage study is the best data available on DBCM for

derivation of the MCLG at this time. EPA does not plan to conduct

additional chronic studies for DBCM but is conducting additional

toxicokinetics and short term drinking water studies on DBCM to better

understand the potential risk associated with exposure through drinking

water.

4. MCLG for Bromoform

    a. Today's Rule. The final MCLG for bromoform is zero. The zero

MCLG is based on a weight-of-evidence classification that bromoform is

a probable human carcinogen based on a consideration of all relevant

health data including cancer and noncancer effects. EPA believes the

data are insufficient at this time to determine the mode of

carcinogenic action for bromoform, and therefore a low dose linear

extrapolation approach is used to estimate lifetime cancer risk as a

default.

    b. Background and Analysis. The proposed MCLG for bromoform was

zero. This MCLG was based on an NTP chronic animal carcinogenicity

study (NTP, 1989). Since the proposal, new studies on the genotoxicity

of bromoform were found. However, these new studies do not support

changing the proposed MCLG of zero for bromoform. The final MCLG for

bromoform is therefore zero.

    c. Summary of Comments. Several commenters agreed with EPA's

classification for bromoform as a probable carcinogen. Other commenters

disagreed with this classification stating that there was insufficient

evidence available because tumors were found in only one species and

the increased number of tumors was small. These commenters generally

felt that EPA should use an RfD approach in quantifying the risk for

bromoform. Some commenters encouraged EPA to conduct more experiments

on bromoform toxicity. Some commenters were concerned with the use of a

corn oil gavage study to determine carcinogenic risk.

    In response, although the increase in tumors was small, the

increase was considered significant because large intestine tumors in

both male and female rats are rare and thus provides sufficient

evidence to classify bromoform as a probable human carcinogen. EPA does

not plan on conducting additional chronic testing for bromoform at this

time, but is conducting toxicokinetic studies and shorter term drinking

water studies to better understand the potential risk associated with

exposure to bromoform in drinking water. EPA agrees with commenters

that drinking water studies are preferable to a corn oil gavage study

to assess risk from DBPs in drinking water. However, the NTP corn oil

gavage study is the best data available on bromoform for derivation of

the MCLG.

5. MCLG for Dichloroacetic Acid (DCA)

    a. Today's Rule. The final MCLG for DCA is zero. EPA has developed

a weight-of-evidence characterization for DCA in which it evaluated all

relevant health data (both cancer and noncancer effects). The MCLG of

zero is based on sufficient evidence of carcinogenicity in animals

which indicates that DCA is a probable human carcinogen (likely under

proposed cancer guidelines). EPA believes the data are insufficient at

this time to determine the mode of carcinogenic action for DCA and that

the data is insufficient to quantify the potential cancer risk from

DCA.

    b. Background and Analysis. EPA proposed an MCLG of zero for DCA.

This was based on classifying DCA as a probable human carcinogen in

accordance with the 1986 EPA Guidelines for Carcinogen Risk Assessment

(EPA, 1986). The DCA categorization was based primarily on findings of

liver tumors in rats and mice, which was regarded as ``sufficient''

evidence in animals. No lifetime risk calculation was conducted at the

time of the proposal because there was insufficient data to quantify

the risk (EPA, 1994a).

    As pointed out in the 1997 and 1998 DBP NODAs, several

toxicological studies have been identified for DCA since the 1994

proposal (EPA, 1997c). In addition, EPA co-sponsored an ILSI project in

which an expert panel was



[[Page 69403]]



convened to explore the application of the EPA's 1996 Proposed

Guidelines for Carcinogen Risk Assessment (EPA, 1996b) to the available

data on the potential carcinogenicity of chloroform and DCA. The panel

considered data on DCA which included chronic rodent bioassay data and

information on mutagenicity, tissue toxicity, toxicokinetics, and other

mode of action information. The panel concluded that the potential

human carcinogenicity of DCA ``cannot be determined'' primarily because

of the lack of adequate rodent bioassay data (ILSI, 1997).

    EPA prepared a new hazard characterization regarding the potential

carcinogenicity of DCA in humans (EPA, 1998b). One objective of this

report was to develop a weight-of-evidence characterization using the

principles of the EPA's 1996 Proposed Guidelines for Carcinogen Risk

Assessment (EPA, 1996b) which are consistent with the 1986 Guidelines.

Another objective of the report was to consider new data since the 1994

proposal and to address the issues raised by the 1997 ILSI panel

report.

    EPA agreed with the ILSI panel report that the mode of action

through which DCA induces liver tumors in both rats and mice cannot be

reasonably determined at this time. EPA disagrees with the ILSI panel

that the potential human carcinogenicity cannot be determined. Based on

the hepatocarcinogenic effects of DCA in both rats and mice in multiple

studies, as well as other date, for example, showing that DCA alters

cell replication and gene expression, EPA concludes that DCA should be

considered as a ``likely'' (probable) cancer hazard to humans (EPA,

1998b). Therefore, as in the 1994 proposed rule, EPA believes that the

MCLG for DCA should remain zero to assure public health protection.

    c. Summary of Comments. Some commenters agreed with the zero MCLG

for DCA based on positive carcinogenic findings in two animal species.

Several commenters stated that a zero MCLG was inappropriate due to

evidence which indicates a nongenotoxic mode of action for DCA. The

comment was raised that the animal evidence was insufficient to

consider DCA a likely (probable) human carcinogen, and that DCA should

be considered at most suggestive of carcinogenicity.

    In response, EPA concludes that DCA should be considered as a

probable (likely under the 1996 proposed guidelines) cancer hazard to

humans (EPA, 1998b) based on the hepatocarcinogenic effects of DCA in

both rats and mice in multiple studies, and mode of action related

effects (e.g., mutational spectra in oncogenes, elevated serum

glucocorticoid levels, alterations in cell replication and death). EPA

considers the mode of action through which DCA induces liver tumors in

both rats and mice to be unclear, and thus the likelihood of human

hazard associated with low levels of DCA usually encountered in the

environment or in drinking water is not sufficiently understood. EPA

acknowledges that a mutagenic mechanism (i.e., direct DNA reactivity)

may not be an important influence on the carcinogenic process at low

doses. EPA believes that the lack of mutagenicity is not a sufficient

basis to depart from a low dose linear default extrapolation approach

for the cancer assessment. There must be other convincing evidence to

explain how the tumors are caused by the chemical. The commenters have

not presented such evidence. Although DCA tumor effects are associated

with high doses used in the rodent bioassays, there is uncertainty

regarding whether the mode of tumorgenesis is solely through mechanisms

that are operative only at high doses. Therefore, as in the 1994

proposed rule, EPA believes that the MCLG for DCA should remain as zero

to assure public health protection. NTP is implementing a new two year

rodent bioassay that will include full histopathology at lower doses

than those previously studied. Additionally, studies on the mode of

carcinogenic action are being done by various investigators including

the EPA health research laboratory.

6. MCLG for Trichloroacetic Acid (TCA)

    a. Today's Rule. The final MCLG for TCA is 0.3 mg/L, as was

proposed in 1994. This MCLG is based on developmental toxicity and

limited evidence of carcinogenicity in animals.

    b. Background and Analysis. The 1994 proposed rule included a MCLG

of 0.3 mg/L for TCA based on developmental toxicity and possible

carcinogenicity based on limited evidence in animal studies (i.e.,

hepatocarcinogenicity in mice). Since the proposal, a 2-year

carcinogenicity study on TCA (DeAngelo et al., 1997) found that TCA was

not carcinogenic in male rats. As was discussed in the 1997 DBP NODA

(EPA, 1997b), there have also been several recent studies examining the

mode of carcinogenic action for TCA. These new studies suggest that TCA

does not operate via mutagenic mechanisms. For a more in depth

discussion of this new data refer to the 1997 DBP NODA (EPA, 1997b) and

related support documents (EPA, 1997c). This new information does not

alter the original assessment of the health effects of TCA based on

developmental toxicity and limited evidence of carcinogenicity.

Therefore, the MCLG will remain 0.3 mg/L.

    c. Summary of Comments. Several commenters agreed with the

classification of TCA as a possible human carcinogen. One commenter

felt that toxicity data on TCA indicated a threshold. Some commenters

disagreed with the study selected for estimating the RfD (Smith et al.

1989). Some commenters stated the uncertainty factors used to establish

the RfD were too high.

    In response, EPA acknowledges that a DNA reactive mutagenic

mechanism may not be involved in TCA's mode of carcinogenicity. Because

an RfD was used in lieu of a quantitative cancer assessment for

establishing the MCLG, however, there was no need to evaluate the mode

of carcinogenic action for TCA at this time. EPA believes that the

Smith et al. (1989) study is appropriate to use in quantifying risk

from TCA since developmental toxicity was the most critical effect. EPA

believes that an uncertainty factor of 3,000 is appropriate to account

for inter and intraspecies differences (100), a lowest observed adverse

effects level (LOAEL) (10), and lack of a two-generation reproductive

study (3) (EPA, 1994a). These uncertainty factors are consistent with

current Agency science policy on using uncertainty factors (EPA,

1994a).

7. MCLG for Chlorite and MRDLG for Chlorine Dioxide

    a. Today's Rule. The final MCLG for chlorite is 0.8 mg/L and the

final MRDLG for chlorine dioxide is 0.8 mg/L. The MCLG for chlorite was

increased from the proposed value of 0.08 mg/L to 0.8 mg/L based on a

weight-of-evidence evaluation of all health data on chlorite including

a recent two-generation reproductive rat study sponsored by the

Chemical Manufactures Association (CMA, 1996). The MRDLG for chlorine

dioxide was increased from the proposed value of 0.3 mg/L to 0.8 mg/L

based on a weight-of-evidence evaluation using all the health data on

chlorine dioxide including the information on chlorite from the CMA

study. EPA believes that data on chlorite are relevant to assessing the

risks of chlorine dioxide because chlorine dioxide is rapidly reduced

to chlorite. Therefore, the findings from the CMA study and previously

described studies in the 1994 proposal were used to assess the risk for

both chlorite and chlorine dioxide.

    b. Background and Analysis. The 1994 proposal included an MCLG of



[[Page 69404]]



0.08 mg/L for chlorite. The proposed MCLG was based on an RfD of 3 mg/

kg/d estimated from a lowest-observed-adverse-effect-level (LOAEL) for

neurodevelopmental effects identified in a rat study by Mobley et al.

(1990). This determination was based on a weight of evidence evaluation

of all the available data at that time (EPA, 1994d). An uncertainty

factor of 1000 was used to account for inter-and intra-species

differences in response to toxicity (a factor of 100) and to account

for use of a LOAEL (a factor of 10).

    The 1994 proposal included an MRDLG of 0.3 mg/L for chlorine

dioxide. The proposed MRDLG was based on a RfD of 3 mg/kg/d estimated

from a no-observed-adverse-effect-level (NOAEL) for developmental

neurotoxicity identified from a rat study (Orme et al., 1985; EPA,

1994d). This determination was based on a weight of evidence evaluation

of all available health data at that time (EPA, 1994a). An uncertainty

factor of 300 was applied that was composed of a factor of 100 to

account for inter-and intra-species differences in response to toxicity

and a factor of 3 for lack of a two-generation reproductive study

necessary to evaluate potential toxicity associated with lifetime

exposure. To fill this important data gap, the CMA sponsored a two-

generation reproductive study in rats (CMA, 1996).

    As described in more detail in the 1998 NODA (EPA, 1998a), EPA

reviewed the CMA study and completed an external peer review of the

study (EPA, 1997d). In addition, EPA reassessed the noncancer health

risk for chlorite and chlorine dioxide considering the new CMA study

(EPA, 1998d). This reassessment was also peer reviewed (EPA, 1998d).

Based on this reassessment, EPA requested comment in the 1998 NODA

(EPA, 1998a) on changing the proposed MCLG for chlorite from 0.08 mg/L

to 0.8 mg/L based on the NOAEL identified from the new CMA study which

reinforced the concern for neurodevelopmental effects associated with

short-term exposures.

    EPA determined that the NOAEL for chlorite should be 35 ppm (3 mg/

kg/d chlorite ion, rounded) based on a weight-of-evidence approach. The

data considered to support the NOAEL are summarized in EPA (1998d) and

included the CMA study as well as previous reports on developmental

neurotoxicity and other adverse health effects (EPA, 1998d). EPA

continues to believe, as stated in the 1998 NODA (EPA, 1998a), that the

RfD for chlorite should be 0.03 mg/kg/d (NOAEL of 3 mg/kg/d with an

uncertainty factor of 100) and that a MCLG of 0.8 mg/L is appropriate.

EPA has concluded that the RfD for chlorine dioxide should be 0.03 mg/L

(NOAEL of 3 mg/kg/d with an uncertainty factor of 100) and that a MRDLG

of 0.8 mg/L is appropriate.

    c. Summary of Comments. EPA received numerous comments on the 1994

proposal (EPA, 1994a) and 1998 NODA (EPA, 1998a). The major comment

from the 1994 proposal was that reliance on the Mobley et al. (1990)

study for the MCLG for chlorite and the Orme et al. (1985) study for

chlorine dioxide were inappropriate and that the results from the CMA

study must be evaluated before any conclusions on the MCLG for chlorite

or chlorine dioxide could be drawn. In relation to the 1998 NODA,

several commenters supported changing the MCLG for chlorite and MRDLG

for chlorine dioxide while others were concerned that the science did

not warrant a change in these values. The major comments submitted

against raising the MCLG and MRDLG focused on several issues. First,

one commenter argued that the 1000-fold uncertainty factor used for

chlorite in the proposal should remain in place because the CMA study

used to reduce the uncertainty factor was flawed. Second, several

commenters indicated that the LOAEL should be set at the lowest dose

level (35 ppm) because certain effects at the lowest dose tested may

have been missed. Finally, some commenters argued that an additional

safety factor should be included to protect children and drinking water

consumption relative to the body weight of children should be used

instead of the default assumption of 2 L per day and 70 kg adult body

weight.

    EPA agrees with commenters on the 1994 proposal that the results

from the CMA should be factored into any final decision on the MCLG for

chlorite and chlorine dioxide. As explained in more detail in the 1998

DBP NODA (EPA, 1998a), EPA considered the findings from the CMA study

along with other available data to reach its conclusions regarding the

MCLG and MRDLG for chlorite and chlorine dioxide.

    EPA disagrees with the commenter who suggested that the 1000-fold

uncertainty factor for chlorite should remain because the CMA study was

flawed. The study design for the neurodevelopmental component of the

CMA study was in accordance with EPA's testing guidelines at the time

the study was initiated. EPA had previously reviewed the study protocol

for the CMA neurotoxicity component and had approved the approach.

While EPA initially had some questions regarding the design of the

neurodevelopmental component of the study (Moser, 1997), subsequent

information submitted by the CMA provided clarification on certain

aspects of the study design (CMA, 1998). EPA agrees that even with the

clarifications that there are some limitations with the

neurodevelopmental component of the CMA study. EPA believes that the

neuropathology components of the CMA study were adequate. The

functional operation battery had some shortcomings in that forelimb and

hindlimb grip strength and foot splay were not evaluated. EPA believes

the results from the motor activity component of the CMA study were

difficult to interpret because of the high variability in controls.

However, in its evaluation of the MCLG for chlorite and chlorine

dioxide, EPA did not rely solely on the CMA study, but used a weight-

of-evidence approach that included consideration of several studies.

Thus, the shortcomings of one study are offset by the weight from other

studies. EPA believes that the CMA study contributes to the weight-of

the-evidence. The studies by Orme et al. (1985), Mobley et al. (1990),

and CMA (1996) support a NOAEL of 3 mg/kg/d based on neurodevelopmental

effects (e.g., decreased exploratory, locomotor behavior, decreased

brain weight). Furthermore, the CMA study was reviewed by outside

scientists as well as by EPA scientists. EPA's re-assessment for

chlorite and chlorine dioxide presented in the 1998 March NODA was

reviewed internally and externally in accordance with EPA peer-review

policy. The three outside experts who reviewed the Agency's assessment

agreed with the NOAEL of 3 mg/kg/day and the derived RfD.

    Finally, EPA disagrees that an additional safety factor should be

applied to provide additional protection for children or that drinking

water consumption relative to the body weight of children should be

used in developing the MCLG. The MCLG and MRDLG presented for chlorite

and chlorine dioxide are considered to be protective of susceptible

groups, including children, given that the RfD is based on a NOAEL

derived from developmental testing, which includes a two-generation

reproductive study. A two-generation reproductive study evaluates the

effects of chemicals on the entire developmental and reproductive life

of the organism. Additionally, current methods for developing RfDs are

designed to be protective for sensitive populations. In the case of

chlorite and chlorine dioxide a factor of 10 was used to account for

variability between the average human response and the



[[Page 69405]]



response of more sensitive individuals. In addition, the important

exposure is that of the pregnant and lactating female and the nursing

pup. The 2 liter per day water consumption and the 70 kg body weight

assumptions are viewed as adequately protective of all groups.

    Based on a review of all the data and public comments, EPA believes

that the MCLG for chlorite should be 0.8 mg/L and the MRDLG for

chlorine dioxide should be 0.8 mg/L. EPA believes the MCLG and MRDLG

are consistent with the discussions during the regulatory negotiations

which recognized the need for an acceptable two-generation reproductive

study prior to reducing the uncertainty factors for chlorite and

chlorine dioxide. EPA believes the CMA provided an acceptable two-

generation study with which to reduce the uncertainty factors. In

addition, EPA believes potential health concerns in the proposal with

having a MCLG for chlorite significantly below the MCL are no longer

relevant because the MCL for chlorite in today's rule will remain at

1.0 mg/L while the MCLG has been revised to 0.8 mg/L. Given the margin

of safety that is factored into the estimation of the MCLG of 0.8 mg/L,

EPA believes that the MCL of 1.0 mg/L will be protective of public

health of all groups, including fetuses and children.

    The MCLG for chlorite is based on an RfD of 0.03 mg/kg/d using a

NOAEL of 3 mg/kg/d and an uncertainty factor of 100 to account for

inter- and intra-species differences. The MCLG for chlorite is

calculated to be 0.8 mg/L by assuming an adult tap water consumption of

2 L per day for a 70 kg adult and using a relative source contribution

of 80% (because most exposure to chlorite is likely to come from

ingestion of drinking water--EPA,1998u). A more detailed discussion of

this assessment is included in the public docket for this rule (EPA,

1998d).

[GRAPHIC] [TIFF OMITTED] TR16DE98.001



    For chlorine dioxide the MCLG is based on a NOAEL of 3 mg/kg/d and

applying an uncertainty factor of 100 to account for inter-and intra-

species differences in response to toxicity, the revised MRDLG for

chlorine dioxide is calculated to be 0.8 mg/L. This MRDLG takes into

account an adult tap water consumption of 2 L per day for a 70 kg adult

and applies a relative source contribution of 80% (because most

exposure to chlorine dioxide is likely to come from ingestion of

drinking water--EPA, 1998u). A more detailed discussion of this

assessment is included in the public docket for this rule (EPA, 1998d).

[GRAPHIC] [TIFF OMITTED] TR16DE98.002



8. MCLG for Bromate

    a. Today's Rule. The final MCLG for bromate is zero. The zero MCLG

is based on a weight-of-evidence evaluation of both the cancer and

noncancer effects which indicates there is sufficient laboratory animal

data to conclude that bromate is a probable (likely under the 1996

proposed cancer guidelines) human carcinogen. EPA believes the data are

insufficient at this time to determine the mode of carcinogenic action

for bromate, and therefore a low dose linear extrapolation approach is

used to estimate lifetime cancer risk as a default.

    b. Background and Analysis. The 1994 proposed rule included a MCLG

of zero for bromate based on a determination that bromate was a

probable human carcinogen. This determination was based on results from

a two species rodent bioassay by Kurokawa et al. (1986a and 1986b) that

found kidney tumors in rats. Since the 1994 proposed rule, EPA has

completed and analyzed a new chronic cancer study in male rats and mice

for potassium bromate (DeAngelo et al., 1998). EPA reassessed the

cancer risk associated with bromate exposure (EPA, 1998e), had this

reassessment peer reviewed (EPA, 1998e), and presented its findings in

the March 1998 NODA (EPA, 1998a). The new rodent cancer study by

DeAngelo et al. (1998) contributes to the weight of the evidence for

the potential human carcinogenicity of potassium bromate and confirms

the study by Kurokawa et al. (1986 a,b).

    c. Summary of Comments. Several commenters supported the zero MCLG

for bromate. Others believed the MCLG of zero was not justified because

there is evidence of a carcinogenic threshold. This evidence indicates

that bromate causes DNA damage indirectly via lipid peroxidation, which

generates oxygen radicals which in turn induce DNA damage. Other

commenters argued that even if there is no carcinogenic threshold, EPA

has overstated the potency of bromate by using the linearized

multistage model and should instead use the Gaylor-Kodell model.

    In response, EPA disagrees with commenters who believed that the

zero MCLG was inappropriate. At this time, under the principles of both

the 1986 EPA Guidelines for Carcinogen Risk Assessment (EPA, 1986) and

the draft 1996 EPA Proposed Guidelines for Carcinogen Risk Assessment

(EPA, 1996b) weight-of-evidence approach, bromate is considered to be a

probable or likely human carcinogen. This weight of evidence conclusion

of potential human carcinogenicity is based on sufficient experimental

findings that include the following: tumors at multiple sites in rats;

tumor responses in both sexes; and evidence for mutagenicity including

point mutations and chromosomal aberrations in in vitro genotoxicity

assays. Furthermore, EPA believes there is insufficient evidence at

this time to draw conclusions regarding the mode of carcinogenic action

for bromate. EPA acknowledges there are studies available showing that

bromate may generate oxygen radicals which increase lipid peroxidation

and damage DNA. However, no data are available that link this proposed

mechanism to tumor induction. Thus, EPA believes that while there are

studies which provide some evidence to support the commenters' claims,

these studies are insufficient at this time to establish



[[Page 69406]]



lipid peroxidation and free radical production as key events

responsible for the induction of the multiple tumor responses seen in

the bromate rodent bioassays (EPA, 1998e). Given the uncertainty about

the mode of carcinogenic action for bromate, EPA believes it is

appropriate to use the default assumption of low dose linearity to

estimate the cancer risk and establish the MCLG of zero for bromate.

EPA is conducting additional studies investigating the mode of action

for bromate.

    EPA also disagrees with commenters who suggested that the Gaylor-

Kodell model should be used for low-dose extrapolation of the bromate

data. In the 1998 NODA, a low dose linear extrapolation of the DeAngelo

et al. (1998) data was conducted using a one-stage Weibull time-to-

tumor model. The Weibull model was considered to be the preferred

approach to account for the reduction in animals at risk that may be

due to the decreased survival observed in the high dose group toward

the end of the study. The estimate of cancer risk from the DeAngelo et

al. (1998) study is similar with the risk estimate derived from the

Kurokawa et al. (1986a) study presented in the 1994 proposed rule.

    Based on an evaluation of all the data and after review and

consideration of the public comments, EPA believes the MCLG for bromate

should be zero.

9. MCLG for Chloral Hydrate

    a. Today's Rule. EPA has decided to not include an MCLG for chloral

hydrate in the Stage 1 DBPR. This decision is based on an analysis of

the technical comments and on the fact that chloral hydrate will be

controlled by the MCLs for TTHM and HAAs and by the treatment technique

of enhanced coagulation.

    b. Background and Analysis. The 1994 proposed rule included an MCLG

for chloral hydrate of 0.04 mg/L. This was based on a 90-day mice study

by Sanders et al. (1982) which reported liver toxicity. A RfD of 0.0016

mg/kg/d was used (LOAEL of 16 mg/kg/d with an uncertainty factor of

10,000). In the 1997 DBP NODA (EPA,1997b) and supporting documents

(EPA, 1997c), additional studies on chloral hydrate were discussed,

however, these new studies did not indicate a change in the MCLG for

chloral hydrate.

    c. Summary of Comments. The majority of commenters disagreed with

the MCLG of 0.04 mg/L for chloral hydrate. Several commenters

questioned the need for an MCLG for chloral hydrate. These commenters

mentioned its low toxic potential and the fact that safe concentrations

of chloral hydrate are substantially greater than those present in

drinking water. Commenters also questioned the need for an MCLG for

chloral hydrate because the MCLs for THMs and HAAs and the treatment

technique of enhanced coagulation will adequately control for chloral

hydrate and because there were no monitoring provisions proposed. Other

commenters argued that the use of a 10,000 uncertainty factor and the

selection of the Sanders et al. (1982) study as a basis for setting the

MCLG were inappropriate.

    In response, EPA agrees with commenters that an MCLG for chloral

hydrate is not needed. This is based on the fact that the TTHM and HAA

MCLs and the treatment technique (i.e., enhanced coagulation/softening)

will control for chloral hydrate, as well as other chlorination

byproducts. In addition, chloral hydrate does not serve as an important

indicator for other chlorination byproducts. The final rule, therefore,

does not contain an MCLG for chloral hydrate. In light of this

decision, EPA is not responding to comments on the uncertainty factor

used as the basis for setting the MCLG.

10. MRDLG for Chlorine

    a. Today's Rule. EPA is promulgating an MRDLG of 4 mg/L for

chlorine based on a NOAEL from a chronic study in animals.

    b. Background and Analysis. EPA proposed an MRDLG of 4 mg/L for

chlorine. The MRDLG was based on a two-year rodent drinking water study

in which chlorine was given to rats at doses ranging from 4 to 14 mg/

kg/day and mice at doses ranging from 8 to 24 mg/kg/day (NTP, 1990).

Neither systemic toxicity, nor effects on body weight and survival were

found. Thus, the MRDLG was based on a NOAEL of 14 mg/kg/day and

application of a 100 fold uncertainty factor to account for inter- and

intra-species differences (EPA, 1994a). New information on chlorine has

become available since the 1994 proposal and was discussed in the 1997

DBP NODA and is included in the public docket (EPA, 1997c). This new

information did not contain data that would change the MRDLG. EPA has

therefore decided to finalize the proposed MRDLG of 4 mg/L for

chlorine.

    c. Summary of Comments. Several commenters agreed with EPA's

conclusion that there is no animal evidence of carcinogenicity for

chlorine. Some commenters also agreed with EPA that 4 mg/L was the

appropriate MCLG. Several commenters agreed with the proposed relative

source contribution of 80 percent for chlorine. Some commenters agreed

with the uncertainty factor of 100 while others felt that it was too

high. Some commenters encouraged EPA to consider children in estimating

risk from chlorine.

    In response, EPA believes that an uncertainty factor of 100 is

appropriate when a NOAEL from a chronic animal study is the basis for

the RfD. Because current methods for developing RfDs are designed to be

protective for sensitive subpopulations, the uncertainty factor of 100

is considered protective of children. Furthermore, animal studies

indicate that chlorine is not a developmental toxicant.

11. MRDLG for Chloramine

    a. Today's Rule. EPA is promulgating an MRDLG of 4 mg/L for

chloramines based on a NOAEL from a chronic rodent study.

    b. Background and Analysis. The 1994 proposed Stage I DBPR included

an MRDLG for chloramines at 4 mg/L based on a NOAEL of 9.5 mg/kg/d for

lack of toxicity in chronic rodent drinking water study and on

application of an uncertainty factor of 100 to account of inter- and

intra-species differences (EPA, 1994h). New information on chloramines

has become available since the 1994 proposal and was included in the

1997 DBP NODA and is included in the public docket (EPA, 1997c). This

new information did not contain data that would change the MRDLG. EPA

has therefore decided to finalized the proposed MRDLG of 4 mg/L for

chloramines.

    c. Summary of Comments. Several commenters agreed with the MRDLG of

4 mg/L for chloramine (as chlorine). Some commenters felt that the

MRDLG was too low due to conservative uncertainty factors. Many

commenters agreed with EPA's conclusion that there is no animal

evidence of carcinogenicity for chloramines. Many commenters agreed

with the RSC of 80% for chloramine while other believed that the RSC

should be higher.

    In response, EPA believes that the uncertainty factor of 100 in the

MRDLG calculation is appropriate to protect public health including

that of children and sensitive subpopulations. EPA believes that the 80

percent is an appropriate ceiling for the RSC due to lack of exposure

data on other sources of exposure.



B. Epidemiology



1. Cancer Epidemiology

    a. Today's Rule. EPA has evaluated all of the cancer epidemiology

data and the corresponding public comments received on the 1994

proposal (EPA,



[[Page 69407]]



1994a), 1997 NODA (EPA, 1997b), and 1998 NODA (EPA, 1998a). Based on

this evaluation, EPA believes that the cancer epidemiology data

provides important information that contributes to the weight-of-

evidence evaluation on the potential health risks from exposure to

chlorinated drinking water. At this time, however, the cancer

epidemiology studies are insufficient to establish a causal

relationship between exposure to chlorinated drinking water and cancer;

and are thus considered limited for use in quantitative risk

assessment. EPA's weight-of-evidence evaluation of the potential risk

posed by chlorinated drinking water is further discussed in section IV

of this preamble.

    b. Background and Analysis. The preamble to the 1994 proposed rule

discussed numerous cancer epidemiology studies that had been conducted

over the past 20 years to examine the relationship between exposure to

chlorinated water and cancer (EPA, 1994a). At the time of the

regulatory negotiation, there was disagreement among the members of the

Reg. Neg. Committee on the conclusions that could be drawn from these

studies. Some members of the Committee felt that the cancer

epidemiology data, taken in conjunction with the results from

toxicological studies, provide ample and sufficient weight-of-evidence

to conclude that exposure to DBPs in drinking water could result in

increased cancer risk at levels encountered in some public water

supplies. Other members of the Committee concluded that the cancer

epidemiology studies on the consumption of chlorinated drinking water

to date were insufficient to provide definitive information for the

regulation.

    In the 1998 DBP NODA (EPA, 1998a), EPA discussed several new

epidemiology studies that had been published since the 1994 proposal.

EPA concluded in the 1998 NODA, based on a review of all the cancer

epidemiology studies (including the more recent studies), that a causal

relationship between exposure to chlorinated surface water and cancer

has not yet been demonstrated. However, several studies have suggested

a weak association in various subgroups. Results from recent

epidemiology studies continue to support the decision to pursue

regulations to provide additional DBP control measures as discussed in

section IV.D of this preamble.

    c. Summary of Comments. Several commenters agreed with EPA's

characterization that there was insufficient evidence to conclude that

there was a causal relationship between exposure to chlorinated surface

water and cancer. Other commenters disagreed with this characterization

stating that they believed the evidence did indicate there was a strong

association between exposure to chlorinated water and cancer. Other

commenters stated that EPA had not clearly articulated the basis for

its conclusions on the issue of causality.

    In response, EPA continues to believe that there is insufficient

evidence, based on the epidemiology data, to conclude there is a causal

association between exposure to chlorinated waters and cancer. EPA

agrees, however, that the basis for its conclusion on causality was not

clearly articulated. This judgement of causality was based on

evaluating the existing cancer epidemiologic database for the following

criteria: strength of association, consistency of the findings,

specificity of the association, as well as other information concerning

the temporal sequence and presence of a dose-response relationship, and

biological plausibility (Federal Focus, 1996; EPA, 1986; EPA 1996b).

    EPA applied the criteria stated above to assess the possible

causality of cancer using the best available cancer epidemiology

studies (Cantor et al., 1985, McGeehin et al., 1993, King and Marrett,

1996, Cantor et al., 1998, Freedman et al., 1997, Hildesheim et al.,

1998, Doyle et al., 1997). These studies found a weak association for

bladder cancer, although the findings were not consistent within and

among the studies. The specificity of the association, temporal

association, and dose response relationship remain unknown. In

addition, the biological mode of action has not been determined. Using

the criteria for causality, the present epidemiologic data do not

support a causal relationship between exposure to chlorinated drinking

water and development of cancer at this time. This conclusion does not

preclude the possibility that a causal link may be established at a

later date by future epidemiology and toxicology studies.

    Some commenters argued that the epidemiological evidence indicated

an increased risk for cancer by exposure to chlorinated drinking water,

while others argued that the epidemiological evidence does not support

a health effects concern. As stated above, EPA believes that, at this

time, a causal link between exposure to chlorinated drinking water and

development of cancer cannot be determined. However, EPA believes that

the epidemiological evidence suggests a potential increased risk for

bladder cancer. It is therefore prudent public health policy to protect

against this potential public health concern in light of the

uncertainties and given the large population (over 200 million people)

potentially exposed.

2. Reproductive and Developmental Epidemiology

    a. Today's Rule. EPA has evaluated all of the reproductive and

developmental epidemiology data and the public comments received on the

1994 proposal, 1997 NODA, and the 1998 NODA. Based on this evaluation,

EPA believes that the reproductive and developmental epidemiology data

provides important information that contributes to the weight-of-

evidence evaluation on the potential risks from exposure to chlorinated

drinking water. However, the reproductive epidemiology studies are

insufficient to establish a causal relationship between exposure to

chlorinated drinking water and reproductive and developmental effects

and are limited for use in the quantification of risk.

    b. Background and Analysis. In the preamble to the 1994 proposed

DBPR, EPA discussed several reproductive epidemiology studies (EPA,

1994a). At the time of the proposal, EPA concluded that there was no

compelling evidence to indicate a reproductive and developmental hazard

due to exposure to chlorinated water because the epidemiologic evidence

was inadequate and the toxicological data were limited. In 1993, an

expert panel of scientists was convened by the International Life

Sciences Institute to review the available human studies for

developmental and reproductive outcomes and to provide research

recommendations (EPA/ILSI, 1993). The expert panel concluded that the

epidemiologic results should be considered preliminary given that the

research was at a very early stage (EPA/ILSI, 1993; Reif et al., 1996).

The 1997 NODA and the supporting documents (EPA, 1997c) presented

several new studies (Savitz et al., 1995; Kanitz et al. 1996; and Bove

et al., 1996) that had been published since the 1994 proposed rule and

the 1993 ILSI panel review. Based on the new studies presented in the

1997 NODA, EPA stated that the results were inconclusive with regard to

the association between exposure to chlorinated waters and adverse

reproductive and developmental effects (EPA, 1997b).

    In the 1998 DBP NODA (EPA, 1998a), EPA included the recommendations

from an EPA convened expert panel in July 1997 to evaluate

epidemiologic studies of adverse reproductive or developmental outcomes

that may be associated with the consumption of disinfected drinking

water published



[[Page 69408]]



since the 1993 ILSI panel review. A report was prepared entitled ``EPA

Panel Report and Recommendations for Conducting Epidemiological

Research on Possible Reproductive and Developmental Effects of Exposure

to Disinfected Drinking Water'' (EPA, 1998f). The 1997 expert panel was

also charged to develop an agenda for further epidemiological research.

The 1997 panel concluded that the results of several studies suggest

that an increased relative risk of certain adverse outcomes may be

associated with the type of water source, disinfection practice, or THM

levels. The panel emphasized, however, that most relative risks are

moderate or small and were found in studies with limitations in design

or conduct. The small magnitude of the relative risk found may be due

to one or more sources of bias, as well as to residual confounding

(factors not identified and controlled). Additional research is needed

to assess whether the observed associations can be confirmed. In

addition, the 1998 DBP NODA included a summary of a study by Waller et

al. (1998) conducted in California and another study by Klotz and Pyrch

(1998) conducted in New Jersey. EPA concluded that while the Waller et

al. (1998) study does not prove that exposure to THMs in drinking water

causes early term miscarriages, it does provide important new

information that needs to be explored and that the study adds to the

weight-of-evidence which suggests that exposure to DBPs may have an

adverse health effect on humans. EPA indicated that the review of the

Klotz and Pyrch study (1998) had not been completed in time for the

1998 NODA.

    EPA has completed its review of the Klotz and Pyrch (1998) study

and concluded that the results in the report provide limited evidence

to substantiate the hypothesis that DBPs in drinking water cause

adverse reproductive or developmental effects since the bulk of the

findings are inconclusive. There is, however, a suggestion in the study

that total THMs or some other component of surface water is associated

with a small increased risk of neural tube defects; no significant

associations, however, were observed with individual THMs, HAAs or

other composite measures of exposure.

    c. Summary of Comments. Several commenters agreed with EPA's

conclusions on the significance of the reproductive and developmental

effects from the various studies. Others believed EPA had not

accurately characterized the potential adverse reproductive and

developmental effects from exposure to DBPs in drinking water.

    In response, EPA continues to believe that the available

epidemiology data along with the toxicological findings suggest that

exposure to DBPs may have adverse effects on humans. However, EPA

believes the epidemiology evidence is insufficient at this time to

conclude that there is a causal association between exposure to DBPs

and adverse reproductive and developmental effects. As noted in the

1998 NODA, EPA has an epidemiology and toxicology research program that

is examining the relationship between exposure to DBPs and adverse

reproductive and developmental effects. In addition, EPA is pursuing

appropriate follow-up studies to see if the observed association in the

Waller et al. (1998) study can be replicated elsewhere. EPA will also

be working with the California Department of Health Services to improve

estimates of exposure to DBPs in the existing Waller et al. study

population. EPA will collaborate with the Centers for Disease Control

and Prevention (CDC) in a series of studies to evaluate if there is an

association between exposure to DBPs in drinking water and birth

defects. EPA is also involved in a collaborative testing program with

the NTP under which several individual DBPs have been selected for

reproductive and developmental laboratory animal studies. This

information will be used in developing the Stage 2 DBPR.



C. MCLs and BAT for TTHM, HAA5, Chlorite, and Bromate; MRDLs and BAT

for Chlorine, Chloramines, and Chlorine Dioxide



    MCLs are enforceable standards which are established as close to

the MCLG as feasible. Feasible means with the use of the best

technology, treatment techniques, and other means which the

Administrator finds available (taking costs into consideration) after

examining for efficacy under field conditions and not solely under

laboratory conditions.

    EPA is promulgating MCLs for two groups of DBPs and two inorganic

byproducts. EPA is also promulgating MRDLs for three disinfectants. EPA

is promulgating these MCLs and MRDLs at the levels proposed in 1994.

Systems will determine compliance with the MCLs and MRDLs in the same

manner as was proposed in 1994, except for chlorite. EPA determined

that additional monitoring requirements for chlorite were necessary

based on the findings from the CMA two-generation reproductive and

developmental study.

    Along with introducing the concept of the MRDLG in the proposed

rule, EPA also introduced the MRDL for the three disinfectants

(chlorine, chloramines, and chlorine dioxide). The MRDLs are

enforceable standards, analogous to MCLs, which recognize the benefits

of adding a disinfectant to water on a continuous basis and to maintain

a residual to control for pathogens in the distribution system. As with

MCLs, EPA has set the MRDLs as close to the MRDLGs as feasible. The

Agency has also identified the BAT which is feasible for meeting the

MRDL for each disinfectant.

    EPA received similar comments on the use of the term MRDL as with

MRDLG. The majority of commenters agreed with the use of the term MRDL

for the disinfectants and therefore EPA is using the term MRDL in the

final rule.

1. MCLs for TTHMs and HAA5

    a. Today's Rule. In today's rule, EPA is promulgating an MCL for

TTHMs of 0.080 mg/L. TTHM is the sum of measured concentrations of

chloroform, bromodichloromethane, dibromochloromethane, and bromoform.

EPA is also promulgating an MCL for HAA5 of 0.060 mg/L. HAA5 is the sum

of measured concentrations of mono-, di-, and trichloroacetic acids,

and mono- and dibromoacetic acids. A system is in compliance with these

MCLs when the running annual average of quarterly averages of all

samples taken in the distribution system, computed quarterly, is less

than or equal to the MCL. If the running annual average computed for

any quarter exceeds the MCL, the system is out of compliance. EPA

believes that by meeting MCLs for TTHMs and HAA5, water suppliers will

also control the formation of other DBPs not currently regulated that

may also adversely affect human health.

    EPA has identified the best available (BAT) technology for

achieving compliance with the MCLs for both TTHMs and HAA5 as enhanced

coagulation or treatment with granular activated carbon with a ten

minute empty bed contact time and 180 day reactivation frequency

(GAC10), with chlorine as the primary and residual disinfectant, as was

proposed in 1994.

    b. Background and Analysis. The 1994 proposal for the Stage 1 DBPR

included MCLs for TTHM and HAA5 at 0.080 and 0.060 mg/L, respectively

(EPA, 1994a). In addition to the proposed MCLs, subpart H systems--

utilities treating either surface water or groundwater under the direct

influence of surface water--that use conventional treatment (i.e.,

coagulation, sedimentation, and filtration) or precipitative softening

would be



[[Page 69409]]



required to remove DBP precursors by enhanced coagulation or enhanced

softening. The removal of TOC would be used as a performance indicator

for DBP precursor control.

    As part of the proposed rule, EPA estimated that 17% of PWSs would

need to change their treatment process to alternative disinfectants

(ozone or chlorine dioxide) or advanced precursor removal (GAC or

membranes) in order to comply with the Stage 1 requirements. This

evaluation was important to assist in determining whether the proposed

MCLs were achievable and at what cost. This evaluation required an

understanding of the baseline occurrence for the DBPs and TOC being

considered in the Stage 1 DBPR, an understanding of the baseline

treatment in-place, and an estimation of what treatment technologies

systems would use to comply with the Stage 1 DBPR requirements.

    In 1997, at the direction of the M-DBP Advisory Committee, the TWG

reviewed MCL compliance predictions developed for the 1994 proposal

because of concern by several Committee members that modifications to

the rule would result in more PWSs not being able to meet the new TTHM

and HAA5 MCLs without installation of higher cost technologies such as

ozone or GAC. Some members were concerned that allowing disinfection

inactivation credit prior to precursor removal (by enhanced coagulation

or enhanced softening) in order to prevent significant reductions in

microbial protection would result in higher DBP formation and force

systems to install alternative disinfectants or advanced precursor

removal to meet the 1994 proposed TTHM and HAA5 MCLs. As discussed

later in today's document in Section III.E (Preoxidation CT Credit),

most PWSs can achieve significant reduction in DBP formation through

the combination of enhanced coagulation (or enhanced softening) while

maintaining predisinfection. The TWG's analysis indicated that there

would be a decrease in the percentage of PWSs that would need to

install higher cost technologies. This decrease was attributed to

changes in the proposed IESWTR which altered the constraints by which

systems could comply with the MCLs. The requirements of the IESWTR

would also prevent significant reduction in microbial protection as

described in the 1997 NODA (EPA, 1997a) and elsewhere in today's

Federal Register. EPA has included a discussion of the prediction of

technology choices in Section IV (Economic Analysis) of today's rule

and a more detailed discussion in the RIA for this rule (EPA, 1998g).

EPA continues to believe the proposed MCLs are achievable without

large-scale technology shifts.

    c. Summary of Comments. Several commenters questioned whether the

TTHM MCL of 0.080 mg/L and the HAA5 MCL of 0.060 mg/L were set at a

level that would preclude the use of chlorine as an effective

disinfectant. EPA does not believe the MCLs will preclude the use of

chlorine. While there are currently systems that are exceeding these

MCLs, the Agency has concluded that most systems will be able to

achieve compliance by relatively low cost alternatives such as:

improved DBP precursor removal through enhanced coagulation or enhanced

softening; moving the point of disinfection to reduce the reaction

between chlorine and DBP precursors; the use of chloramines for

residual disinfection instead of chlorine; or a combination of these

alternatives.

    Many commenters also questioned the need for a modified TTHM MCL

and a new MCL for HAA5. As discussed in section I.B.2. of today's rule,

EPA believes the potential public health risks do justify a reduction

in exposure to DBPs and hence a modification in the MCL for TTHMs and a

new MCL for HAA5. Also as discussed in section IV of this rule, EPA

continues to believe that the potential risks associated with both TTHM

and HAA5 and unregulated DBPs will be reduced by the combination of

these MCLs and DBP precursor removal through enhanced coagulation and

enhanced softening.

    While most commenters agreed with EPA's definition of GAC10 and

GAC20 (GAC with a 10 and a 20 minute empty bed contact time,

respectively), several commenters thought that designating GAC as BAT

meant that they would have to install GAC at their treatment plant. EPA

is required to designate a BAT for any MCL that the Agency promulgates;

however, a system may use any technology it wants to comply with the

MCL. However, a system must install BAT prior to the State issuing a

variance to one of these MCLs.

    Commenters also questioned the use of group MCLs for TTHM and HAA5,

instead of MCLs for the individual DBPs, since a group MCL does not

take into account differing health effects and potencies of individual

DBPs. EPA continues to believe that regulating TTHMs and HAAs as group

MCLs is appropriate at this time for several reasons. First, EPA does

not have adequate occurrence data for individual trihalomethanes and

haloacetic acids to develop national occurrence estimates which are

needed for estimating the potential costs and benefits of the rule

(although the Agency has an adequate database of group occurrence).

Second, there is not an adequate understanding of how water quality

parameters (such as pH, temperature, bromide, and alkalinity) affect

individual THM and HAA formation. Third, EPA does not have an adequate

understanding of how treatment technologies control the formation of

individual THMs and HAAs to enable specifying appropriate MCLs for

individual TTHMs or HAAs at this time. Finally, there are inadequate

health data to characterize the potential health risks for several of

the HAAs and to then determine the potential benefits from reduction in

exposures. In conclusion, EPA continues to believe the most appropriate

approach for reducing the health risk from all DBPs is by the

combination of TTHM and HAA5 MCLs and DBP precursor removal.

    Some commenters stated that EPA may have underestimated HAA

formation, especially in certain areas of the country. The Agency was

aware that waters in particular regions of the country would be more

difficult to treat in order to control for HAA5 than for TTHM. Based on

additional data received since the proposal, EPA continues to believe

that the HAA5 MCL can be met by most systems through the same general

low-cost strategies as used for TTHM (e.g., improved DBP precursor

removal, moving the point of disinfection, use of chloramines for

residual disinfection) rather than higher cost alternatives (see

section IV.C for cost estimates of technology treatment choices).

    Many commenters also requested that States be granted sufficient

flexibility in implementing this rule. While the State must adopt rules

that are at least as stringent as those published in today's rule, EPA

has given the States and systems much latitude in monitoring plans

(frequency and location), allowable disinfectants, and other rule

elements. Much of this flexibility carries over from the 1979 TTHM Rule

(EPA, 1979).

    Finally, some commenters stated that requirements in this rule are

complicated. EPA acknowledges that this rule is complicated, but that

this complexity is necessary in order to adequately and economically

address the potential DBP risks. EPA was required to consider a host of

complicating factors in developing regulatory requirements: different

disinfectants, different health effects (acute and chronic), different

DBP formation kinetics, different source water types and qualities,

different treatment processes, and the need for



[[Page 69410]]



simultaneous compliance with other rules such as the Total Coliform

Rule, Lead and Copper Rule, and Interim Enhanced Surface Water

Treatment Rule. The Agency chose to evaluate all these factors by

developing requirements that minimized impacts on various classes of

systems while enabling States to implement the rule. In addition to the

further description of the requirements in today's rule, EPA will

publish a State implementation manual, a small system compliance

manual, and a series of guidance manuals that will provide additional

information to systems and States in implementing this rule.

    EPA has reviewed all comments and determined that the requirements

promulgated today are necessary to control the occurrence of TTHM and

HAA5 and are feasible to achieve. These requirements take into account

the difficulties in simultaneously controlling risks from DBPs and

pathogens, while appropriately addressing implementation and compliance

issues.

2. MCL for Bromate

    a. Today's Rule. In today's rule, EPA is promulgating an MCL for

bromate of 0.010 mg/L. Bromate is one of the principal byproducts of

ozonation in bromide-containing source waters. The proposed MCL for

bromate was 0.010 mg/l. A system is in compliance with the MCL when the

running annual average of monthly samples, computed quarterly, is less

than or equal to the MCL. If the running annual average computed for

any quarter exceeds the MCL, the system is out of compliance. EPA has

identified the BAT for achieving compliance with the MCL for bromate as

control of ozone treatment process to reduce formation of bromate, as

was proposed in 1994 (EPA, 1994a).

    b. Background and Analysis. For systems using ozone, a separate MCL

was proposed for the primary inorganic DBP associated with ozone usage:

bromate. Although the theoretical 10<SUP>-4</SUP> risk level for

bromate is 0.005 mg/l, an MCL of 0.010 mg/L was proposed because

available analytical detection methods for bromate were reliable only

to the projected practical quantification limit (PQL) of 0.01 mg/L

(EPA, 1994a).

    In the preamble to the proposed rule, EPA requested comment on

whether there were ways to set (or achieve) a lower MCL (i.e., 0.005

mg/L [5 <greek-m>g/L]) and whether the PQL for bromate could be lowered

to 5 <greek-m>g/L in order to allow compliance determinations for a

lower MCL in Stage 1 of the proposed rule. The proposed MCL of 0.010

mg/L for bromate was based on a projected PQL that would be achieved by

improved methods. The PQL of the revised method is approximately 0.010

mg/L for bromate, as discussed in Section III.G (Analytical Methods).

At the time of the November 1997 NODA, EPA was not aware of any new

information that would lower the PQL for bromate and thus allow

lowering the MCL. As a result, EPA concluded that the proposed bromate

MCL was appropriate.

    c. Summary of Comments. Several commenters were concerned that the

bromate MCL may have been set at a level that would preclude the use of

ozone. During the M-DBP Advisory Committee discussions, the TWG

evaluated the feasibility of ozone for certain systems that were

predicted to have problems in complying with the TTHM and HAA5 MCLs.

While ozone was not feasible for all systems, it was feasible for many

that did not have elevated source water bromide levels to react with

ozone to form bromate. The TWG predicted that most of the systems not

able to use ozone would be able to switch to chlorine dioxide for

primary disinfection.

    EPA has reviewed all comments and determined that the requirements

promulgated today are necessary to control the occurrence of bromate

and are feasible to achieve. For additional discussion on the treatment

technologies for controlling bromate formation and their costs see the

Cost and Technology Document for Controlling Disinfectants and

Disinfection Byproducts (EPA, 1998k). These requirements take into

account the difficulties in simultaneously controlling risks from DBPs

and pathogens, while appropriately addressing compliance and

implementation issues. In addition, the Reg. Neg. Committee and the M-

DBP Advisory Committee supported these conclusions.

3. MCL for Chlorite

    a. Today's Rule. In today's rule, EPA is promulgating an MCL for

chlorite of 1.0 mg/L. EPA has modified the monitoring requirements from

the proposed rule for the reasons discussed in section III.A.7. The

issue of monitoring and MCL compliance determinations as they relate to

the health effect of concern for chlorite were discussed in the

proposed rule (EPA, 1994a). CWSs and NTNCWSs using chlorine dioxide for

disinfection or oxidation are required to conduct sampling for chlorite

both daily at the entrance to the distribution system and monthly (3

samples on the same day) within the distribution system. Additional

distribution system monitoring is required when the chlorite

concentration measured at the entrance to the distribution system

exceeds a chlorite concentration of 1.0 mg/L. Distribution system

monitoring may be reduced if certain conditions are met (described in

section III.H of this rule).

    b. Background and Analysis. For systems using chlorine dioxide, EPA

proposed a separate MCL for chlorite associated with its usage in 1994.

The proposed chlorite MCL of 1.0 mg/L was supported by the Reg. Neg.

Committee because 1.0 mg/L was the lowest level considered practicably

achievable by typical systems using chlorine dioxide, from both

treatment and monitoring perspectives. The MCLG was 0.08 mg/L, due (in

part) to data gaps that required higher uncertainty factors in the MCLG

determination. The CMA agreed to fund new health effects research on

chlorine dioxide and chlorite--with EPA approval of the experimental

design--to resolve these data gaps. EPA completed its review of the

study and published its findings in a NODA in March 1998. Those

findings led to a chlorite MCLG of 0.8 mg/L and support for an MCL of

1.0 mg/L.

    c. Summary of Comments. Many commenters requested that EPA not

modify the MCL for chlorite prior to receipt and evaluation of the CMA

study, since lowering the MCL could preclude the use of chlorine

dioxide for drinking water disinfection. EPA has evaluated the CMA

study and concluded that the MCLG for chlorite should be 0.8 mg/L. EPA

believes the proposed MCL of 1.0 mg/L, based on a three sample average

to determine compliance, is appropriate because this is the lowest

level achievable by typical systems using chlorine dioxide. In

addition, considering the margin of safety that is factored into the

estimate of the MCLG, EPA believes the MCL will be protective of public

health. Once the final MCLG was established, EPA decided that the

chlorite MCL should be finalized at the level proposed which was as

close as economically and technically feasible to the MCLG, and

modified the proposed requirements for monitoirng and compliance in

response to the health concerns associated with chlorite.

    EPA has reviewed all comments and determined that the requirements

promulgated today are necessary to control the occurrence of chlorite

and are feasible to achieve. These requirements take into account the

difficulties in simultaneously controlling risks from DBPs and

pathogens, while appropriately addressing compliance and



[[Page 69411]]



implementation issues. In addition, the Reg. Neg. Committee and the M-

DBP Advisory Committee supported these conclusions.

4. MRDL for Chlorine

    a. Today's Rule. Chlorine is a widely used and highly effective

water disinfectant. In today's rule, EPA is promulgating an MRDL for

chlorine of 4.0 mg/L. As a minimum, CWSs and NTNCWSs must measure the

residual disinfectant level at the same points in the distribution

system and at the same time as total coliforms, as specified in

Sec. 141.21. Subpart H systems may use the results of residual

disinfectant concentration sampling done under the SWTR

(Sec. 141.74(b)(6) for unfiltered systems, Sec. 141.74(c)(3) for

systems that filter) in lieu of taking separate samples. Monitoring for

chlorine may not be reduced.

    A system is in compliance with the MRDL when the running annual

average of monthly averages of all samples, computed quarterly, is less

than or equal to the MRDL. Notwithstanding the MRDL, operators may

increase residual chlorine levels in the distribution system to a level

and for a time necessary to protect public health to address specific

microbiological contamination problems (e.g., including distribution

line breaks, storm runoff events, source water contamination, or cross-

connections).

    EPA has identified the best means available for achieving

compliance with the MRDL for chlorine as control of treatment processes

to reduce disinfectant demand, and control of disinfection treatment

processes to reduce disinfectant levels.

    b. Background and Analysis. The 1994 proposed Stage I DBPR included

an MRDL for chlorine at 4.0 mg/L (EPA, 1994a). The MRDL for chlorine is

equal to the MRDLG for chlorine. EPA requested comment on a number of

issues relating to the calculation of the MRDLG for chlorine. New

information on chlorine has become available since the 1994 proposal

and was discussed in the 1997 NODA (EPA, 1997b). EPA believes that no

new information has become available to warrant changing the proposed

MRDL. EPA has therefore decided to promulgate the MRDL of 4.0 mg/L for

chlorine.

    c. Summary of Comments. Some commenters expressed concern that the

MRDL for chlorine is too high. These commenters were concerned that 4

mg/L levels of chlorine would have a detrimental effect on piping

materials and would cause taste and odor problems. One commenter

supported the chlorine MRDL and the methods of calculating compliance

with the MRDL. This commenter felt that 4.0 mg/L appropriately allows

for disinfection under varying circumstances. One commenter requested

that EPA increase the flexibility of utilities to meet the MRDL for

chlorine during periods when chlorine levels in the distribution

systems may need to be raised to protect public health.

    EPA believes that the MRDL of 4.0 mg/L for chlorine is appropriate

to control for potential health effects (MRDLG is 4.0 mg/L) from

chlorine while high enough to allow for control of pathogens under a

variety of conditions. EPA also believes that compliance based on a

running annual average of monthly averages of all samples, computed

quarterly is sufficient to allow systems to increase residual chlorine

levels in the distribution system to a level and for a time necessary

to protect public health to address specific microbiological

contamination problems and still maintain compliance. If a system has

taste and odor problems associated with excess chlorine levels it can

lower its level of chlorine. Since there may not be any health effects

associated with taste and odor problems, EPA does not have a statutory

requirement to address this concern.

5. MRDL for Chloramines

    a. Today's Rule. Chloramines are formed when ammonia is added

during chlorination. In today's rule, EPA is promulgating an MRDL for

chloramines of 4.0 mg/L (measured as combined total chlorine). As a

minimum, CWSs and NTNCWSs must measure the residual disinfectant level

at the same points in the distribution system and at the same time as

total coliforms, as specified in Sec. 141.21. Subpart H systems may use

the results of residual disinfectant concentration sampling done under

the SWTR (Sec. 141.74(b)(6) for unfiltered systems, Sec. 141.74(c)(3)

for systems that filter) in lieu of taking separate samples. Monitoring

for chloramines may not be reduced.

    A PWS is in compliance with the MRDL when the running annual

average of monthly averages of all samples, computed quarterly, is less

than or equal to the MRDL. Notwithstanding the MRDL, operators may

increase residual chloramine levels in the distribution system to a

level and for a time necessary to protect public health to address

specific microbiological contamination problems (e.g., including

distribution line breaks, storm runoff events, source water

contamination, or cross-connections).

    EPA has identified the best means available for achieving

compliance with the MRDL for chloramines as control of treatment

processes to reduce disinfectant demand, and control of disinfection

treatment processes to reduce disinfectant levels.

    b. Background and Analysis. The 1994 proposed Stage 1 DBPR included

an MRDL for chloramines at 4.0 mg/L (EPA, 1994a). The MRDL for

chloramines is equal to the MRDLG for chloramines. EPA requested

comment on a number of issues relating to the calculation of the MRDLG

for chloramines. New information on chloramines has become available

since the 1994 proposal and was cited in the 1997 NODA and is included

in the public docket for this rule (EPA, 1997b). This new information

did not contain data that would warrant changing the MRDL. EPA has

therefore decided to promulgate the proposed MRDL of 4.0 mg/L for

chloramines.

    c. Summary of Comments. Some commenters remarked that systems with

high concentrations of ammonia would have difficulty meeting the MRDL

for chloramine of 4.0 mg/L and still maintain adequate microbial

protection. One commenter felt that there should not be a limit for

chloramine residual due to variations in parameters such as

distribution system configurations and temperature. One commenter felt

that the MRDL for chloramines was too low and should not be set at the

same level as the chlorine MRDL since chlorine is a stronger

disinfectant than chloramines. This commenter felt that limiting the

chloramine residual would reduce the capability to sustain high water

quality in the distribution system. One commenter supported the

chloramine MRDL and the methods of calculating compliance with the

MRDL. This commenter felt that 4.0 mg/L adequately allows for

disinfection under varying circumstances.

    EPA believes that compliance based on a running annual average of

monthly averages of all samples, computed quarterly, is sufficient to

allow systems to increase residual chloramine levels in the

distribution system to a level and for a time necessary to protect

public health to address specific microbiological contamination

problems and still maintain compliance. The MRDL for chloramine does

not limit disinfectant dosage but rather disinfectant residual in the

distribution system. EPA therefore, believes that systems with high

levels of ammonia should be able to comply with the MRDL. Systems that

have difficulty sustaining high water quality in the distribution

system should consider modifying their



[[Page 69412]]



treatment or maintenance procedures to reduce demand. Although chlorine

is a stronger disinfectant than chloramine, EPA believes that an MRDL

of 4.0 mg/L is sufficient to provide adequate microbial protection.

6. MRDL for Chlorine Dioxide

    a. Today's Rule. Chlorine dioxide is used primarily for the

oxidation of taste and odor-causing organic compounds in water. It can

also be used for the oxidation of reduced iron and manganese and color,

and as a disinfectant and algicide. Chlorine dioxide reacts with

impurities in water very rapidly, and is dissipated quickly. In today's

rule, EPA is promulgating an MRDL of 0.8 mg/L for chlorine dioxide.

Unlike chlorine and chloramines, the MRDL for chlorine dioxide may not

be exceeded for short periods of time to address specific

microbiological contamination problems because of potential health

concerns with short-term exposure to chlorine dioxide above the MCL.

    CWSs and noncommunity systems must monitor for chlorine dioxide

only if chlorine dioxide is used by the system for disinfection or

oxidation. Monitoring for chlorine dioxide may not be reduced. If

monitoring is required, systems must take daily samples at the entrance

to the distribution system. If any daily sample taken at the entrance

to the distribution system exceeds the MRDL, the system is required to

take three additional samples in the distribution system on the next

day. Systems using chlorine as a residual disinfectant and operating

booster chlorination stations after the first customer must take three

samples in the distribution system: one as close as possible to the

first customer, one in a location representative of average residence

time, and one as close as possible to the end of the distribution

system (reflecting maximum residence time in the distribution system).

Systems using chlorine dioxide or chloramines as a residual

disinfectant or chlorine as a residual disinfectant and not operating

booster chlorination stations after the first customer must take three

samples in the distribution system as close as possible to the first

customer at intervals of not less than six hours.

    If any daily sample taken at the entrance to the distribution

system exceeds the MRDL and if, on the following day, any sample taken

in the distribution system also exceeds the MRDL, the system will be in

acute violation of the MRDL and must take immediate corrective action

to lower the occurrence of chlorine dioxide below the MRDL and issue

the required acute public notification. Failure to monitor in the

distribution system on the day following an exceedance of the chlorine

dioxide MRDL shall also be considered an acute MRDL violation.

    If any two consecutive daily samples taken at the entrance to the

distribution system exceed the MRDL, but none of the samples taken in

the distribution system exceed the MRDL, the system will be in nonacute

violation of the MRDL and must take immediate corrective action to

lower the occurrence of chlorine dioxide below the MRDL. Failure to

monitor at the entrance to the distribution system on the day following

an exceedance of the chlorine dioxide MRDL shall also be considered a

nonacute MRDL violation.

    EPA has identified the best means available for achieving

compliance with the MRDL for chlorine dioxide as control of treatment

processes to reduce disinfectant demand, and control of disinfection

treatment processes to reduce disinfectant levels.

    b. Background and Analysis. EPA proposed an MRDL for chlorine

dioxide of 0.8 mg/L in 1994. The MRDL was determined considering the

tradeoffs between chemical toxicity and the beneficial use of chlorine

dioxide as a disinfectant. The Reg. Neg. Committee agreed to this MRDL

with the reservation that it would be revisited, if necessary, after

completion of a two-generation reproductive study by CMA.

    As discussed above for chlorite, a two-generation reproductive

study on chlorite, which is relevant to health effects of chlorine

dioxide, was completed by the CMA. EPA completed its review of this

study and published its findings in a NODA in March 1998 (EPA, 1998a).

Based on its assessment of the CMA study and a reassessment of the

noncancer health risk for chlorite and chlorine dioxide, EPA concluded

that the MRDLG for chlorine dioxide be changed from 0.3 mg/L to 0.8 mg/

L. Since this new MRDLG was equal to the proposed MRDL for chlorine

dioxide, the MRDL will remain 0.8 mg/L.

    c. Summary of Comments. A number of commenters were concerned that

the MRDL for chlorine dioxide not be lowered below the proposed level

of 0.8 mg/L because this would preclude the use of chlorine dioxide as

a water disinfectant. One commenter supported the MRDL for chlorine

dioxide based on public health protection, adequate microbial

protection, and technical feasibility. One commenter agreed that a

running annual average of samples for compliance determination should

not be allowed for chlorine dioxide. One commenter was concerned that

the chlorine dioxide MRDL was too high and that EPA should consider

children and vulnerable populations in establishing drinking water

standards.

    EPA has reassessed the health effects data on chlorine dioxide,

including the new CMA two-generation study and determined that the MRDL

should remain at 0.8 mg/L as proposed. EPA believes that this MRDL is

set at a technically feasible level for the majority of chlorine

dioxide plants. This is the case because EPA considered children and

susceptible populations in its MRDLG determination (EPA, 1998h). The

MRDL is set as close to this MRDLG as is technically and economically

feasible.



D. Treatment Technique Requirement



1. Today's Rule

    Today's rule establishes treatment technique requirements for

removal of TOC to reduce the formation of DBPs by means of enhanced

coagulation or enhanced softening. The treatment technique applies to

Subpart H systems using conventional filtration treatment regardless of

size. Subpart H systems are systems with conventional treatment trains

that use surface water or ground water under the influence of surface

water as their source. The treatment technique requirement has two

steps of application. Step 1 specifies the percentage of influent TOC a

plant must remove based on the raw water TOC and alkalinity levels. The

matrix in Table III-1 specifies the removal percentages.



    Table III-1.--Required Removal of Total Organic Carbon by Enhanced Coagulation and Enhanced Softening for

                               Subpart H Systems Using Conventional Treatment <SUP>a,\<SUP>b

----------------------------------------------------------------------------------------------------------------

                                                                      Source water alkalinity (mg/L as CaCO<INF>3)

                                                                 -----------------------------------------------

                     Source water TOC (mg/L)                            0-60          >60-120          >120<SUP>c

                                                                     (percent)       (percent)       (percent)

----------------------------------------------------------------------------------------------------------------

>2.0-4.0........................................................            35.0            25.0            15.0



[[Page 69413]]





>4.0-8.0........................................................            45.0            35.0            25.0

>8.0............................................................            50.0            40.0            30.0

----------------------------------------------------------------------------------------------------------------

<SUP>a Systems meeting at least one of the conditions in Section 141.135(a)(2) (i)-(vi) of the rule are not required

  to meet the removals in this table.

<SUP>b Softening systems meeting one of the two alternative compliance criteria in Section 141.135(a)(3) of the rule

  are not required to meet the removals in this table.

<SUP>c Systems practicing softening must meet the TOC removal requirements in the last column to the right.



    Step 2 provides alternate performance criteria when it is

technically infeasible for systems to meet the Step 1 TOC removal

requirements. For systems practicing enhanced coagulation, Step 2 of

the treatment technique requirement is used to set an alternative TOC

removal requirement (i.e. alternative percent removal of raw water TOC)

for those systems unable to meet the TOC removal percentages specified

in the matrix. The alternative TOC removal percentage is determined by

performing jar tests on at least a quarterly basis for one year. During

the jar tests, alum or an equivalent dose of ferric coagulant is added

in 10 mg/L increments until the pH is lowered to the target pH value.

The target pH is the value the sample must be at or below before the

incremental addition of coagulant can be discontinued. For the

alkalinity ranges 0-60, >60-120, >120-240, and >240 mg/L (as

CaCO<INF>3</INF>), the target pH values are 5.5, 6.3, 7.0, and 7.5,

respectively. Once the Step 2 jar test is complete, the TOC removal

(mg/L) is then plotted versus coagulant dose (mg/L). The alternative

TOC removal percentage is set at the point of diminishing returns

(PODR) identified on the plot.

    Today's rule defines the PODR as the point on the TOC versus

coagulant dose plot where the slope changes from greater than 0.3/10 to

less than 0.3/10 and remains less than 0.3/10. After identifying the

PODR, the alternative TOC removal percentage can be set. If the TOC

removal versus coagulant dose plot does not meet the PODR definition,

the water is considered not amenable to enhanced coagulation and TOC

removal is not required if the PWS requests, and is granted, a waiver

from the enhanced coagulation requirements by the State. Systems are

required to meet the alternative TOC removal requirements during full-

scale operation to maintain compliance with the treatment technique.

For the technical reasons outlined in the 1997 DBP NODA (EPA 1997b),

EPA has concluded that this definition of the PODR is a reliable

indicator of the amount of TOC that is feasible to remove.

    Systems practicing enhanced softening are not required to perform

jar testing under today's treatment technique as part of a Step 2

procedure. Rather, they are required to meet one of three alternative

performance criteria if they cannot meet the Step 1 TOC removal

requirements. These criteria are: (1) Produce a finished water with a

SUVA of less than or equal to 2.0 L/mg-m; (2) remove a minimum of 10

mg/L magnesium hardness (as CaCO<INF>3</INF>); or (3) lower alkalinity

to less then 60 mg/L (as CaCO<INF>3</INF>). All three of these

alternative performance criteria are measured monthly and can be

calculated quarterly as a running annual average to demonstrate

compliance. As discussed in the 1997 DBP NODA (EPA 1997b) EPA has not

been able, from a technical and engineering standpoint, to identify a

Step 2 testing procedure at this time that allows softening systems to

set an alternative TOC removal amount. Enhanced softening systems

unable to meet the Step 1 TOC removal requirements or any of the three

alternative performance criteria may apply to the State for a waiver

from the treatment technique requirements. EPA believes the three

alternative performance criteria listed above provide assurance that

softening systems have maximized TOC removal to the extent feasible.

    Today's rule also provides alternative compliance criteria--which

are separate and independent of the Step 2 enhanced coagulation

procedure and the enhanced softening alternative performance criteria--

from the treatment technique requirements provided certain conditions

are met. These criteria are:

    (1) the system's source water TOC is <2.0 mg/L;

    (2) the system's treated water TOC is <2.0 mg/L;

    (3) the system's source water TOC <4.0 mg/L, its source water

alkalinity is >60 mg/L (as CaCO<INF>3</INF>), and the system is

achieving TTHM <40<greek-m>g/L and HAA5 <30<greek-m>g/L (or the system

has made a clear and irrevocable financial commitment to technologies

that will meet the TTHM and HAA level);

    (4) the system's TTHM is <40<greek-m>g/L, HAA5 is <30<greek-m>g/L,

and only chlorine is used for primary disinfection and maintenance of a

distribution system residual;

    (5) the system's source water SUVA prior to any treatment is

<ls-thn-eq> 2.0 L/mg-m; and

    (6) the system's treated water SUVA is <ls-thn-eq> 2.0 L/mg-m.

    Alternative compliance criteria 1, 2, 5, and 6 are determined based

on monthly monitoring calculated quarterly as a running annual average

of all measurements. Alternative compliance criteria 3 is based on

monthly monitoring for TOC and alkalinity or quarterly monitoring for

TTHMs and HAA5, calculated quarterly as a running annual average of all

measurements. Alternative criteria 4 is determined based on monitoring

for TTHMs and HAA5, calculated quarterly as a running annual average of

all measurements. SUVA, an indicator of DBP precursor removal

treatability, is defined as the UV-254 (measured in m<SUP>-1</SUP>)

divided by the DOC concentration (measured as mg/L).

2. Background and Analysis

    The general structure of the 1994 proposed rule and today's final

rule are similar. The 1994 proposal included an enhanced coagulation

and enhanced softening treatment technique requirement for Subpart H

systems. The 1994 proposed rule included a TOC removal matrix for Step

1 TOC removal requirements and it also provided for a Step 2 jar test

procedure for systems practicing enhanced coagulation. The PODR for the

Step 2 procedure was defined as a slope of .3/10 on the TOC removal

versus coagulant dose plot. The Step 2 procedure included a maximum pH

value, now referred to as the ``target pH'' for conducting the jar

tests and it also allowed systems to request a waiver from the State if

the PODR was never



[[Page 69414]]



attained. The target pH values in the 1994 proposal were the same as

those in today's final rule. A Step 2 procedure for enhanced softening

systems was not specified in the proposal.

    The proposed rule also provided for a number of exceptions to the

enhanced coagulation and enhanced softening requirements, but it did

not include use of SUVA as an alternative compliance criteria.

    A major goal of the TOC removal treatment technique requirements

was to minimize transactional costs to the States both in terms of

limiting the number of systems seeking alternative performance criteria

and in providing relatively simple methodologies for determining

alternative performance criteria. In the 1997 DBP NODA (EPA 1997b), EPA

presented new data and analysis and the basis for modifying the

proposed criteria to those described in today's final rule. The 1997

NODA also solicited public comment on EPA's intended changes to the

proposal and the recommendations of the M-DBP Advisory Committee to

EPA. An overview of the key points in the 1997 NODA most pertinent to

modifying the treatment technique requirements are presented below.

    Data Supporting Changes in the TOC Removal Requirements. The

proposed TOC removal percentages, which were set with the intent that

90% of affected systems would be able to achieve them, were developed

with limited data. Since the proposal, several jar studies and analyses

of full-scale plant TOC removal performance have been performed. They

were analyzed by EPA as part of the M-DBP Advisory Committee process.

This data will not be thoroughly reviewed here; instead, the major

points salient to development of the final regulation will be

summarized. See the 1997 DBP NODA (EPA 1997b) to review EPA's detailed

analysis of the new data.

    As discussed in greater detail in the 1997 DBP NODA, research by

Singer et al. (1995) indicated that a significant number of waters,

especially low-TOC, high-alkalinity waters in the first row of the

proposed TOC removal matrix, would probably not be able to meet the TOC

removal percentages and would therefore need to use the Step 2 protocol

to establish alternative performance criteria. The Singer et al. (1995)

study raised concern regarding the number of systems that might need to

use the Step 2 procedure to set alternative performance criteria. A

study by Malcolm Pirnie, Inc. and Colorado University addressed this

issue by developing a nationally representative database of 127 source

waters and used this data to develop a model to predict enhanced

coagulation's ability to remove TOC from different source waters

(Edwards, 1997; Tseng & Edwards, 1997; Chowdhury, 1997). The model was

subsequently used to analyze the level or percentage of TOC removal

that is operationally feasible to achieve for the boxes in the proposed

TOC removal matrix. Nine predictive equations for TOC removal were

developed, one for each box of the TOC removal matrix, to select TOC

removal percentages that could be ``reasonably'' met by 90 percent of

the systems implementing enhanced coagulation. The equations indicated

that many systems having source waters within the low TOC boxes of the

matrix (i.e. 2.0-4.0 mg/L, the first row of the matrix) would meet the

Step 2 slope criterion before meeting the required TOC removal

percentages. In other words, less than 90 percent of the systems in

this row could achieve the proposed TOC removal with reasonable

coagulant doses. The equations indicated that the TOC removal

percentages in the medium and high TOC boxes (the bottom two rows of

the matrix) could be met by approximately 90 percent of the systems in

these boxes. The research team also examined 90th-percentile SUVA

curves, in conjunction with the nine TOC removal curves, to predict

what TOC removal percentage is appropriate for each of the nine boxes

of the matrix.

    An analysis of full-scale TOC removal has also been performed since

1994. Data was obtained from 76 treatment plants of the American Water

Works Service Company (AWWSCo) system, plants studied by Randtke et al.

(1994), and plants studied by Singer et al. (1995). These data

represent a one-time sampling at each plant under current operating

conditions when enhanced coagulation was not being practiced. This

sampling is different from the proposed compliance requirements which

would be based on an annual average of monthly samples. Based on

current treatment at the plants in the study, 83 percent of the systems

treating moderate-TOC, low-alkalinity water removed an amount of TOC

greater than that required by the TOC removal matrix, whereas only 14

percent of the systems treating water with low TOC and high alkalinity

met the proposed TOC removal requirements. The results of the survey,

coupled with the information discussed in the preceding paragraph,

indicate that the proposed TOC removal percentages in the top row of

the matrix might be too high for 90 percent of plants to avoid the Step

2 procedure, while the removal percentages in the bottom two rows may

be reasonable and allow 90 percent of plants to avoid the Step 2

procedure. Therefore, the TOC removal percentages in the first row have

been lowered 5.0 percentage points to enable 90 percent of plants to

comply without unreasonable coagulant dosage or resorting to the Step 2

procedure.

    Data Supporting the Use of SUVA as an Exemption from Treatment

Technique Requirements. At the time of the proposal, insufficient data

on SUVA was available to define precise criteria for when enhanced

coagulation would not be effective for removing DBP precursors. The M-

DBP Advisory Committee examined the role of SUVA as an indicator of the

amount of DBP precursor material enhanced coagulation is capable of

removing. It has been well established that coagulation primarily

removes the humic fraction of the natural organic matter (NOM) in water

(Owen et al., 1993). Furthermore, Edzwald and Van Benschoten (1990)

have found SUVA to be a good indicator of a water's humic content. The

humic fraction of a water's organic content significantly affects DBP

formation upon chlorination.

    A study by White et al. (1997) showed that waters with high initial

SUVA values exhibited significant reductions in SUVA as a result of

coagulation, demonstrating a substantial removal of the humic (and

other UV-absorbing) components of the organic matter, whereas waters

with low initial SUVA values exhibited relatively low reductions in

SUVA. For all of the waters examined, the SUVA tended to plateau at

high alum doses, reflecting that the residual organic matter was

primarily non-humic and therefore unamenable to removal by enhanced

coagulation. SUVA's ability to indicate the amount of humic matter

present, and enhanced coagulation's ability to preferentially remove

humic matter, logically establishes SUVA as an indicator of enhanced

coagulation's ability to remove humic substances from a given water.

The M-DBP Advisory Committee therefore recommended that a SUVA value

<ls-thn-eq> 2.0 L/mg-m be an exemption from the treatment technique

requirement and that this SUVA value also be added as a Step 2

procedure.

    Effect of Coagulant Dose on TOC Removal for Enhanced Softening. At

the time of proposal, limited data was available on the effectiveness

of TOC removal by enhanced coagulation and enhanced softening and on

conditions that define feasibility. Several studies examined the

relationship between increased coagulant dose and TOC removal (Shorney

et al., 1996; Clark et



[[Page 69415]]



al. 1994). These studies indicate some improvement in TOC removal with

small doses of iron salts (5 mg/L ferric sulfate), but no additional

TOC removal during softening occurred with increased coagulant addition

(up to 25 mg/L dose). Pilot testing by the City of Austin's softening

plant confirmed the study's jar test results by showing that increasing

ferric sulfate doses beyond the level required for turbidity removal

provided no additional TOC removal.

    Multiple jar tests on various waters performed by Singer et al.

(1996) examined the relationship between use of lime and soda ash and

TOC removal. Only lime and soda ash (no coagulants) were used in the

tests. The study showed the removal of 10 mg/L of magnesium hardness

would probably have less of an impact on plant residual generation than

using a lime soda-ash process. However, the amount of residual material

generated under both scenarios could be substantial.

    Step 2 Requirements for Softening Systems. As stated above, the

proposed rule did not include a Step 2 procedure for softening plants

because of a lack of data. The M-DBP Advisory Committee examined new

data that had been collected since the proposal to determine if a Step

2 procedure for softening plants could be identified. Data included the

current TOC removals being achieved by softening plants covered by the

ICR (49 plants). The data were analyzed to find the appropriate TOC

removal levels for softening plants. The results of plotting the

average TOC percent removals on a percentile basis indicated that the

relative impact of meeting the TOC removal requirement in the proposed

rule would be greatest in the low TOC group (>2-4 mg/L). However,

forcing a plant to increase pH may require it to add soda ash (due to

the decrease in alkalinity caused by high lime dose necessary to raise

the pH). This would be a significant treatment change due to the

additional solids generation and because significant amounts of

magnesium hydroxide may precipitate at the higher pH. Most softening

plants are normally operated without soda ash addition because of the

high cost of soda ash, the additional sludge production, the increased

chemical addition to stabilize the water, and the increased sodium

levels in the finished water (Randtke et al., 1994 and Shorney et al.,

1996). Due to these difficulties, EPA does not currently believe that a

lime and soda-ash softening process would be a viable Step 2 procedure

for softening systems. The final rule instead specifies two alternative

compliance criteria, mentioned earlier in this section, as a Step 2

procedure for softening systems.

3. Summary of Comments

    A large number of comments on the 1994 proposal questioned whether

the required TOC removal percentages could be obtained by 90 percent of

affected systems. In response, since the time of proposal, a large body

of additional data and analysis has been developed to help address this

question. The analyses discussed above showed that the top row of the

TOC removal matrix needed to be lowered by 5.0 percentage points to

enable 90 percent of systems within the row to achieve the required TOC

removal without unreasonable coagulant doses. Analysis also showed the

TOC removal percentages contained in the two lower rows of the TOC

removal matrix accurately reflected the TOC removal 90 percent of these

systems could remove. EPA believes the final TOC removal matrix, which

includes the adjustments to the top row mentioned above, accurately

reflects the TOC removal that 90 percent of the systems affected by the

rule could practically achieve.

    Commenters questioned why systems that meet the DBP Stage 1 MCLs

for TTHM and HAA5 must still practice enhanced coagulation. The

enhanced coagulation treatment technique is designed to remove DBP

precursor material to help reduce the risks posed by DBPs. Also, EPA

believes that enhanced coagulation would reduce the number of systems

switching to alternative disinfectants, which was a goal of the Reg.

Neg. Committee. EPA believes that even if systems are meeting the MCLs,

an additional risk reduction benefit can be achieved through removal of

DBP precursor material at a relatively low cost to the system.

Therefore, systems that meet the MCLs must still practice enhanced

coagulation to decrease the risks posed by DBPs in general.

    The Agency received numerous comments on the 1994 proposal that

expressed doubt regarding the definition of the PODR. Specifically, the

commenters stated that the accuracy of the slope criterion (0.3 mg/L

TOC removed per 10 mg/L coagulant added) for determining the PODR was

not supported with adequate data. The data developed since the proposal

and the corresponding analysis demonstrate that the slope criterion

accurately predicts the PODR. The analyses discussed above showed that

there is a particular relationship between SUVA and the slope

criterion, namely, that they both predict the PODR at the same point of

the TOC removal versus coagulant dose curve. Since SUVA is a very good

predictor of the humic fraction of TOC, which is the fraction

preferentially removed by enhanced coagulation, and the PODR predicted

by SUVA and the slope criterion agree, EPA believes the slope criterion

of 0.3 mg/L TOC removal per 10 mg/L of coagulant addition accurately

predicts the PODR.

    The majority of commenters did not support requiring the use of

bench-scale filtration as part of the Step 2 enhanced coagulation

procedure. The commenters generally believed that using filtration at

bench scale is of limited value because the great majority of TOC is

removed via sedimentation, not through filtration. Additionally, some

commentors felt that attempting to replicate full-scale filtration at

bench scale can contain inherent inaccuracy. EPA generally agrees that

a Step 2 filtration procedure should not be required. The Agency

believes that most of the TOC removed by conventional treatment plants

is removed in the sedimentation basin rather than in the filters.

Therefore, requiring a bench-scale filtration procedure as part of Step

2 testing will not increase the accuracy of the procedure or its value

to the treatment technique implementation. Accordingly, today's final

rule does not require the use of a bench scale filtration procedure

during Step 2 enhanced coagulation testing. Detailed guidance on

conducting the Step 2 testing will be provided in the Guidance Manual

for Enhanced Coagulation and Enhanced Precipatative Softening.

    Commenters expressed varied opinions regarding the frequency of

Step 2 testing. Several commenters stated that the rule should not set

a minimum testing frequency, but that it should be left to State

discretion based on source water characteristics. Other commenters

believed a minimum of quarterly monitoring should be required with a

provision for more frequent testing to address source water quality

events. EPA believes that Step 2 testing frequency should be related to

seasonal and other variations in source water quality as these

variations may influence the amount of TOC removal the treatment plant

can achieve. Accordingly, EPA recommends that systems utilizing the

Step 2 procedure for compliance perform Step 2 testing quarterly for

one year after the effective data of the rule. The system may then

apply to the State to reduce testing to a minimum of once per year. If

the State does not approve the request for reduced testing frequency,

the system must continue to test quarterly.



[[Page 69416]]



E. Predisinfection Disinfection Credit



1. Today's Rule

    Today's rule does not impose any constraints on the ability of

systems to practice predisinfection and take microbial inactivation

credit for predisinfection to meet the disinfection requirements of the

SWTR. Utilities are free to take disinfection credit for

predisinfection, regardless of the disinfectant used, for disinfection

that occurs after the last point the source water is subject to surface

water run-off and prior to the first customer.

2. Background and Analysis

    The 1994 proposed Stage 1 DBPR (EPA,1994a) discouraged the use of

disinfectants prior to precursor (measured as TOC) removal by not

allowing compliance credit for the SWTR's disinfection requirements to

be taken prior to removal of a specified percentage of TOC. The

proposed IESWTR options were intended to include microbial treatment

requirements to prevent increases in microbial risk due to the loss of

predisinfection credit. These options were to be implemented

simultaneously with the Stage 1 DBPR. The purpose of not allowing

predisinfection credit was to maximize removal of organic precursors

(measured as TOC) prior to the addition of a disinfectant, thus

lowering the formation of DBPs.

    Many drinking water systems use preoxidation to control a variety

of water quality problems such as iron and manganese, sulfides, zebra

mussels, Asiatic clams, and taste and odor. The 1994 proposed rule did

not preclude the continuous addition of oxidants to control these

problems. However, the proposed regulation, except under a few specific

conditions, did not allow credit for compliance with disinfection

requirements prior to TOC removal. Analysis supporting the proposed

rule concluded that many plants would be able to comply with the Stage

1 MCLs for THMs and HAA5 of 0.080 mg/L and 0.060 mg/L, respectively, by

reductions in DBP levels as a result of reduced disinfection practice

in the early stages of treatment. Also, enhanced coagulation and

enhanced softening were thought to lower the formation of other

unidentified DBPs as well. The 1994 proposal assumed that addition of

disinfectant prior to TOC removal would initiate DBP formation through

contact of the chlorine with the TOC, effectively eliminating the value

of enhanced coagulation for DBP reduction. Finally, the analysis

underlying the 1994 proposed elimination of the preoxidation credit

assumed that the addition of disinfectant was essentially ``mutually

exclusive'' to the goal of reducing DBP formation by the removal of

TOC. As discussed below, new data developed since 1994 suggest this may

not be the case.

    Reasons for Disinfectant Use. In order to obtain information on the

impact that disallowing predisinfection would have on utilities'

disinfection practices, a survey was sent out to ICR utilities to

obtain information on their current predisinfection practices. The

results of the survey of 329 surface water treatment plants indicated

that 80 percent (263) of these plants use predisinfection for one or

more reasons. The survey indicated that the majority of the plants

using predisinfection were doing so for multiple reasons. However, the

main reason reported for predisinfection was microbial inactivation.

Algae control, taste and odor control, and inorganic oxidation, in that

order, were the next most frequently cited reasons for practicing

predisinfection. Seventy-seven percent of plants that predisinfected

reported that their current levels of Giardia lamblia inactivation

would be lowered if predisinfection was discontinued and no subsequent

additional disinfection was added to compensate for change in practice.

Eighty-one percent of plants that predisinfected would have to make

major capital investments to make up for the lost logs of Giardia

lamblia inactivation. For example, to maintain the same level of

microbial protection currently afforded, construction to provide for

additional contact time or use of a different disinfectant might be

needed if predisinfection credit was eliminated.

    In addition to the ICR mail survey, results from EPA's

Comprehensive Performance Evaluations (CPE) from 307 PWSs (4 to 750

mgd) reported that 71% of the total number of plants used

predisinfection and 93% of those that predisinfected used two or three

disinfectant application points during treatment.

    Based on the above information, EPA believes that predisinfection

is used by a majority of PWSs for microbial inactivation, as well as

other drinking water treatment objectives. Therefore, disallowing

predisinfection credit could influence systems to make changes in

treatment to comply with the disinfection requirements of the SWTR or

to maintain current levels of microbial inactivation.

    Impact of Point of Chlorination on DBP Formation. The results of a

study by Summers et al. (1997) indicate that practicing enhanced

coagulation, while simultaneously maintaining prechlorination, can

still result in decreased DBP formation (especially for TOX and TTHM).

Greater benefits are realized by moving the point of chlorination to

post-rapid mixing or further downstream for HAA5 control, and to mid-

flocculation or post-sedimentation for TOX and TTHM control. These data

show that the assumption made in the 1994 proposal, namely that

application of any disinfectant prior to TOC removal would critically

effect DBP formation, was not accurate. The data indicate that

simultaneous employment of enhanced coagulation and predisinfection

does not necessarily mean that DBP formation cannot be substantially

controlled (see EPA 1997b for detailed analysis).

    Impact on Softening Plants. In order to obtain additional

information on the current TOC removals being achieved by softening

plants, a survey was sent to all the ICR softening utilities (49

plants) requesting that they fill out a single page of information with

yearly average, maximum and minimum values for multiple operating

parameters for each softening plant. The survey showed that in spite of

the fact that 78 percent of softening plants are using free chlorine

for at least a portion of their disinfection, 90 percent of plants are

currently meeting an 80 <greek-m>g/L MCL level for TTHMS. All the

softening plants reported average HAA5 levels below 60 <greek-m>g/L.

Without predisinfection credit, these plants may have to provide

disinfection contact time after sedimentation, which could mean

significantly increasing the free chlorine contact time to make up for

a shortened detention time.

3. Summary of Comments

    Most commenters stated that the proposed elimination of

predisinfection would result in many plants not being able to maintain

existing levels of disinfection or comply with the SWTR disinfection

requirements without making significant compensatory changes in their

disinfection practice. Commenters were concerned that without

predisinfection the level of microbial risk their customers were

exposed to could significantly increase, and that eliminating microbial

inactivation credit for predisinfection to comply with the SWTR might

influence utilities to abandon predisinfection to more easily comply

with the TTHM and HAA5 MCLs. EPA agrees with this concern and therefore

the final rule has been modified from the proposal to allow

predisinfection credit.



[[Page 69417]]



F. Requirements for Systems to Use Qualified Operators



    EPA believes that systems that must make treatment changes to

comply with requirements to reduce the microbiological risks and risks

from disinfectants and disinfection byproducts should be operated by

personnel who are qualified to recognize and react to problems.

Therefore, in today's rule, the Agency is requiring that all systems

regulated under this rule be operated by an individual who meets State

specified qualifications, which may differ based on size and type of

the system. Subpart H systems already are required to be operated by

qualified operators under the provisions of the SWTR (40 CFR

141.70(c)). Current qualification or certification programs developed

by the States should, in many cases, be adequate to meet this

requirement for Subpart H systems. Also, States must maintain a

register of qualified operators.

    EPA encourages States which do not already have operator

certification programs in effect to develop such programs. The Reg.

Neg. Committee and TWG believed that properly trained personnel are

essential to ensure safer drinking water. States with existing operator

certification programs may wish to update their programs for qualifying

operators under the SWTR. In these cases, States may wish to indicate

that their operator certification programs are being developed in

accordance with EPA's new guidelines.



G. Analytical Methods



1. Today's Rule

    Chlorine (Free, Combined, and Total). Today's rule approves four

methods for measuring free, combined, and total chlorine to determine

compliance with the chlorine MRDL (using either free or total chlorine)

and chloramines MRDL (using either combined or total chlorine): ASTM

Method D1253-86 (ASTM, 1996), Standard Methods 4500-Cl D (APHA, 1995),

4500-Cl F (APHA, 1995), and 4500-Cl G (APHA, 1995). Additionally, this

rule approves two methods for measuring total chlorine to determine

compliance with the chlorine MRDL and chloramines MRDL: Standard

Methods 4500-Cl E (APHA, 1995) and 4500-Cl I (APHA, 1995). The rule

also contains an additional method for measuring free chlorine to

determine compliance with the chlorine MRDL: Standard Method 4500-Cl H

(APHA, 1995).

    Chlorine Dioxide. Today's rule approves two methods for determining

compliance with the chlorine dioxide MRDL: Standard Methods 4500-

ClO<INF>2</INF> D (APHA, 1995) and 4500-ClO<INF>2</INF> E (APHA 1995).

EPA did not approve Standard Method 4500-ClO<INF>2</INF> C (APHA,

1995), which was included in the 1994 proposed rule. The Agency

determined, in concurrence with the majority of commenters on this

issue, that Standard Method 4500-ClO<INF>2</INF> C is outdated and

inaccurate in comparison to chlorine dioxide methods approved in

today's rule and is inadequate for compliance monitoring.

    TTHM. Today's rule approves three methods for determining

compliance with the TTHM MCL: EPA Methods 502.2 (EPA, 1995), 524.2

(EPA, 1995), and 551.1 (EPA, 1995).

    HAA5. Today's rule approves three methods for determining

compliance with the HAA5 MCL: EPA Methods 552.1 (EPA, 1992) and 552.2

(EPA, 1995) and Standard Method 6251B (APHA, 1995).

    Bromate. Today's rule approves a method for determining compliance

with the bromate MCL: EPA Method 300.1 (EPA, 1997e). EPA has

demonstrated this method to be capable of quantifying bromate at the

MCL of 10 <greek-m>g/L under a wide range of solution conditions. EPA

did not approve EPA Method 300.0 (EPA, 1993b) for bromate analysis,

although this method was included for analysis of bromate in the 1994

proposed rule. As stated in the proposed rule, EPA Method 300.0 is not

sensitive enough to measure bromate at the MCL established in today's

rule. EPA Method 300.1 was developed subsequent to the proposed rule in

order to provide a method with adequate sensitivity to assess bromate

compliance.

    Chlorite. Today's rule approves two methods for determining

compliance with the chlorite MCL: EPA Methods 300.0 (EPA, 1993b) and

300.1 (EPA, 1997e). As described elsewhere in today's rule, chlorite

compliance analyses are made on samples taken in the distribution

system during monthly monitoring, or during additional distribution

system monitoring as required. Today's rule establishes the following

method for daily monitoring of chlorite: Standard Method 4500-

ClO<INF>2</INF> E (APHA, 1995), amperometric titration. As stated

elsewhere in today's rule, daily monitoring of chlorite is conducted on

samples taken at the entrance to the distribution system. Commenters

supported the use of amperometric titration as a feasible method for

daily monitoring of chlorite.

    TOC. Today's Rule approves three methods for TOC analysis: Standard

Methods 5310 B, 5310 C, and 5310 D, as published in the Standard

Methods 19th Edition Supplement (APHA, 1996). EPA believes that all of

these methods can achieve the precision and detection level necessary

for compliance determinations required in today's rule when the quality

control (QC) procedures contained in the method descriptions and this

rule are followed. However, while any of these methods may be used, EPA

advises that a consistent method be employed for all measurements in

order to reduce the impact of possible instrument bias.

    In accordance with the concerns of commenters, today's rule

requires certain QC procedures for TOC analyses in addition to those

contained in the method descriptions. These additional QC steps are

designed to increase the integrity of the analysis and have been found

to be effective in data collection under the ICR. Filtration of samples

prior to TOC analysis is not permitted, as this could result in removal

of organic carbon. Where turbidity interferes with TOC analysis,

samples should be homogenized and, if necessary, diluted with organic-

free reagent water. TOC samples must either be analyzed or must be

acidified to achieve pH less than 2.0 by minimal addition of phosphoric

or sulfuric acid as soon as practical after sampling, not to exceed 24

hours. Samples must be analyzed within 28 days.

    SUVA (Specific Ultraviolet Absorbance). Today's rule establishes

SUVA as an alternative criterion for demonstrating compliance with TOC

removal requirements contained in today's rule. SUVA is a calculated

parameter defined as the UV absorption at 254 nm (UV<INF>254</INF>)

(measured as m<SUP>-1</SUP>) divided by the DOC concentration (measured

as mg/L). If the UV absorption is first determined in units of

cm<SUP>-1</SUP>, the SUVA equation is multiplied by 100 to convert to

m<SUP>-1</SUP>, as shown below:

SUVA = 100 (cm/m) [UV<INF>254</INF> (cm<SUP>-1</SUP>)/DOC (mg/L)]



    Two separate analytical methods are necessary to make this

measurement: UV<INF>254</INF> and DOC. Today's rule approves three

methods for DOC analysis: Standard Methods 5310 B, 5310 C, and 5310 D,

as published in the Standard Methods 19th Edition Supplement (APHA,

1996); and approves Standard Method 5910 B (APHA, 1995) for

UV<INF>254</INF> analysis.

    The final rule contains QC steps for the SUVA analyses that are

required in addition to those mandated in the method descriptions.

These requirements were developed in response to comments solicited by

EPA in the 1997 DBP NODA (EPA, 1997b) and are as follows:





[[Page 69418]]





--sample acquisition (DOC and UV<INF>254</INF> samples used to

determine a SUVA value must be taken at the same time and at the same

location. SUVA must be determined on water prior to the addition of

disinfectants/oxidants.)

--sample preservation (DOC samples must either be analyzed or must be

acidified to achieve pH less than 2.0 by minimal addition of phosphoric

or sulfuric acid as soon as practical after sampling, not to exceed 48

hours. The pH of UV<INF>254</INF> samples may not be adjusted.)

--holding times (DOC samples must be analyzed within 28 days of

sampling. UV<INF>254</INF> samples must be analyzed as soon as

practical after sampling, not to exceed 48 hours.)

--filtration (Prior to analysis, UV<INF>254</INF> and DOC samples must

be filtered through a 0.45 <greek-m>m pore-diameter filter. DOC samples

must be filtered prior to acidification.)

--background concentrations in the filtered blanks (Water passed

through the filter prior to filtration of the sample must serve as the

filtered blank. This filtered blank must be analyzed using procedures

identical to those used for analysis of the samples and must meet the

following criteria: TOC <0.5 mg/L.)



    Bromide. Today's rule approves the following two methods for

monitoring bromide: EPA Methods 300.0 (EPA, 1993b) and 300.1 (EPA,

1997e).

    Alkalinity. Today's rule approves three methods for measuring

alkalinity: ASTM Method D1067-92B (ASTM, 1994), Standard Method 2320 B

(APHA, 1995), and Method I-1030-85 (USGS, 1989).

    pH. Today's rule requires the use of methods that have been

previously approved in Sec. 141.23(k) for measurement of pH.

    Approved analytical methods are summarized in Table III-2.



                                    Table III-2.--Approved Analytical Methods

----------------------------------------------------------------------------------------------------------------

              Analyte                 EPA method             Standard method                     Other

----------------------------------------------------------------------------------------------------------------

Chlorine (free, combined, total)..  ..............  4500-Cl D                         ASTM D1253-8.

                                    ..............  4500-Cl F

                                    ..............  4500-Cl G

(Total)...........................  ..............  4500-Cl E

                                    ..............  4500-Cl I

(Free)............................  ..............  4500-Cl H

Chlorine Dioxide..................  ..............  4500-ClO<INF>2 D

                                    ........<INF>......  4500-ClO<INF>2 E

TTHM..............................           502.2

                                             524.2

                                             551.1

HAA5..............................           552.1  625l B

                                             552.2

Bromate...........................           300.1

Chlorite (monthly)................           300.0

                                             300.1

(Daily)...........................  ..............  4500-ClO<INF>2 E

TOC/DOC...........................  ..............  5310 B

                                    ..............  5310 C

                                    ..............  5310 D

UV<INF>254.............................  ..<INF>............  5910 B

Bromide...........................           300.0

                                             300.1

Alkalinity........................  ..............  2320 B                            ASTM D1067-92B.

                                                                                      USGS I-1030-85.

pH................................           150.1  4500-H+B                          ASTM D1293-84.

                                             150.2  ................................  ..........................

----------------------------------------------------------------------------------------------------------------



2. Background and Analysis

    Chlorine (Free, Combined, and Total). In the 1994 proposed rule,

EPA included all Standard Methods for analysis of free, combined, and

total chlorine that were approved in today's rule.

    Chlorine Dioxide. The 1994 proposed rule included the same three

methods for analyzing chlorine dioxide (ClO<INF>2</INF>) that are

approved under the SWTR and ICR regulations. Two of these methods,

Standard Methods 4500.ClO<INF>2</INF> C (APHA, 1992) and

4500.ClO<INF>2</INF> E (APHA, 1992), are amperometric methods. The

third proposed method was Standard Method 4500.ClO<INF>2</INF> D (APHA,

1992), a colorimetric test using the color indicator N,N-diethyl-p-

phenylenediamine (DPD).

    TTHM. The 1994 proposed rule included three methods for the

analysis of TTHMs. They were EPA Methods 502.2, 524.2, and 551. In

1995, EPA Method 551 was revised to EPA Method 551.1, rev. 1.0 (EPA,

1995), which was approved for ICR monitoring under 40 CFR 141.142.

    EPA Method 551.1 has several improvements upon EPA Method 551. The

use of sodium sulfate is strongly recommended over sodium chloride for

the MTBE extraction of DBPs. This change was in response to a report

indicating elevated recoveries of some brominated DBPs due to bromide

impurities in the sodium chloride (Xie, 1995). Other changes to EPA

Method 551.1 include a buffer addition to stabilize chloral hydrate,

elimination of the preservative ascorbic acid, and modification of the

extraction procedure to minimize the loss of volatile analytes. The

revised method requires the use of surrogate and other quality control

standards to improve the precision and accuracy of the method.

    HAA5. The 1994 proposed rule included two methods for the analysis

of five haloacetic acids--EPA Method 552.1 (EPA, 1992) and Standard

Method 6233B (APHA, 1992). Both methods use capillary column gas

chromatographs equipped with electron capture



[[Page 69419]]



detectors. The two methods differ in the sample preparation steps. EPA

Method 552.1 uses solid phase extraction disks followed by an acidic

methanol derivitization. Standard Method 6233B is a small volume

liquid-liquid (micro) extraction with methyl-t-butyl ether, followed by

a diazomethane derivitization. Following the proposed rule, Standard

Method 6233B was revised and renumbered 6251B (APHA, 1995) to include

bromochloroacetic acid, for which a standard was not commercially

available in 1994. Recognizing these improvements, EPA approved

Standard Method 6251B for analysis under the ICR (40 CFR Part 141 or

EPA, 1996a). Several commenters requested that the revised and

renumbered method, Standard Method 6251B, also be approved for the

analysis of haloacetic acids under the Stage 1 DBPR.

    In 1995 EPA published a third method for HAAs, EPA Method 552.2

(EPA, 1995), and subsequently approved it for HAA analysis under the

1996 ICR (40 CFR Part 141 or EPA, 1996a). EPA Method 552.2 is an

improved method, combining the micro extraction procedure of Standard

Method 6233B with the acidic methanol derivitization procedure of EPA

Method 552.1. It is capable of analyzing nine HAAs.

    Bromate. The 1994 proposed rule required systems that use ozone to

monitor for bromate ion. EPA proposed EPA Method 300.0 (EPA, 1993b) for

the analysis of bromate and chlorite ions. However, at the time of the

proposal, EPA was aware that EPA Method 300.0 was not sensitive enough

to measure bromate ion concentration at the proposed MCL of 10

<greek-m>g/L. EPA recognized that modifications to the method would be

necessary to increase the method sensitivity. Studies at that time

indicated that changes to the injection volume and the eluent chemistry

would decrease the detection limit below the MCL. Many commenters to

the 1994 proposal agreed that EPA Method 300.0 was not sensitive enough

to determine compliance with a MCL of 10 <greek-m>g/L bromate ion,

given that MCLs are typically set at 5 times the minimum detection

levels (MDLs).

    Following the proposal, EPA improved EPA Method 300.0 and

renumbered it as EPA Method 300.1 (EPA, 1997b). EPA Method 300.1

specifies a new, high capacity ion chromatography (IC) column that is

used for the analysis of all anions listed in the method, instead of

requiring two different columns as specified in EPA Method 300.0. The

new column has a higher ion exchange capacity that improves

chromatographic resolution and minimizes the potential for

chromatographic interferences from common anions at concentrations

10,000 times greater than bromate ion. For example, quantification of

5.0 <greek-m>g/L bromate is feasible in a matrix containing 50 mg/L

chloride. Minimizing the interferences permits the introduction of a

larger sample volume to yield method detection limits in the range of

1-2 <greek-m>g/L.

    In the 1997 DBPR NODA (EPA, 1997b), EPA discussed EPA Method 300.1

and projected that by using it laboratories would be able to quantify

bromate with the accuracy and precision necessary for compliance

determination with an MCL of 10 <greek-m>g/L. Although there would be a

limited number of laboratories that would be qualified to do such

analyses, EPA determined that there should be adequate laboratory

capacity for bromate ion compliance monitoring by the time the rule

becomes effective.

    Chlorite. The proposed rule required systems using chlorine dioxide

for disinfection or oxidation to perform monthly monitoring for

chlorite ion in the distribution system. EPA designated EPA Method

300.0 (ion chromatography) for chlorite analysis. EPA considered other

methods using amperometric and potentiometric techniques but decided

that only the ion chromatography method (EPA Method 300.0) would

produce results with the accuracy and precision needed for determining

compliance. Subsequent to the proposed rule, EPA Method 300.0 was

improved in order to achieve lower detection limits for bromate ion and

renumbered as EPA Method 300.1.

    TOC. To satisfy requirements of the Stage 1 DBPR, the 1994 proposed

rule directed that a TOC analytical method should have a detection

limit of at least 0.5 mg/L and a reproducibility of <plus-minus> 0.1

mg/L over a range of 2 to 5 mg/L TOC. The proposed rule included two

methods for analyzing TOC: Standard Methods 5310 C, which is the

persulfate-ultraviolet oxidation method, and 5310 D, the wet-oxidation

method (APHA, 1992). These methods were selected because, according to

data published in Standard Methods (APHA 1992), they could achieve the

necessary precision and detection limit. Standard Method 5310 B, the

high-temperature combustion method, was considered but not proposed

because it was described in Standard Methods (1992, APHA) as having a

detection limit of 1 mg/L. The proposal stated that if planned

improvements to the instrumentation used in Standard Method 5310 B were

successful, the next version would be considered for promulgation.

Revisions of Standard Methods 5310 B, C, and D were published in

Standard Methods 19th Edition Supplement (APHA, 1996). The revised

version of Standard Method 5310 B recognized the capacity of certain

high temperature instruments to achieve detection limits below 1 mg/L

using this method.

    SUVA (Specific Ultraviolet Absorbance). SUVA analytical methods

were not addressed in the 1994 proposed rule because SUVA had not been

developed and proposed as a compliance parameter for TOC removal

requirements at that time. The analytical methods and associated QC

procedures for DOC and UV<INF>254</INF> approved in today's rule are

those on which the Agency solicited comment in the 1997 DBPR NODA (EPA,

1997b).

    Bromide. The 1994 proposed rule included EPA Method 300.0 for

analysis of bromide. EPA believed that the working range of this method

adequately covered the requirements proposed for bromide monitoring. As

described above, EPA developed Method 300.1 for improved bromate

analysis subsequent to the proposed rule. EPA Method 300.1 can also

effectively measure bromide at the concentration of 50 <greek-m>g/L,

required in today's rule for reduced monitoring of bromate.

    Alkalinity. The proposed rule included all methods approved by EPA

for measuring alkalinity. These methods have all been approved in

today's rule.

3. Summary of Comments

    Following is a discussion of major comments on the analytical

methods requirements of the Stage 1 DBPR.

    Chlorine. A commenter to the 1994 proposal recommended approval of

ASTM method D1253-86. EPA determined that this method is equivalent to

Standard Method 4500-Cl D, and has approved this method in today's

rule.

    Chlorine Dioxide. EPA received comments on the proposed rule

detailing weaknesses of the methods selected to calculate

ClO<INF>2</INF>. Commenters pointed out that other halogenated species,

such as free chlorine, chloramines, and chlorite, as well as common

metal ions (e.g. copper, manganese, chromate) will interfere with these

methods. Additionally, where these methods determine concentrations by

difference, they are potentially inaccurate and subject to propagation

of errors. Commenters specifically criticized Standard Method 4500-

ClO<INF>2</INF> C (APHA 1995), amperometric method I, which was

characterized as outdated and inaccurate, and stated that Standard



[[Page 69420]]



Method 4500-ClO<INF>2</INF> E (APHA 1995), amperometric method II, is a

substantially better method. Consequently, in the 1997 DBP NODA, EPA

requested comment on removing Standard Method 4500-ClO<INF>2</INF> C

from the list of approved methods for the analysis of chlorine dioxide

for compliance with the MRDL.

    Comments on the 1997 DBPR NODA favored eliminating Standard Method

4500.ClO<INF>2</INF> C as an approved method for ClO<INF>2</INF>

compliance analysis. EPA does not approve this method in today's rule.

EPA recognizes that the two methods approved for ClO<INF>2</INF>

monitoring under today's rule are subject to interferences. However,

EPA believes that these methods can be used effectively to indicate

compliance with the ClO<INF>2</INF> MRDL when the quality control

procedures contained in the method descriptions are followed. Several

commenters also encouraged EPA to approve a more sensitive and specific

method for ClO<INF>2</INF> analysis, and suggested alternative methods

including Acid Chrome Violet K, Lissamine Green B, and Chlorophenol

Red. While EPA supports the development of improved analytical methods

for chlorine dioxide, the Agency believes that at this time the methods

suggested by commenters have not gone through the necessary performance

validation processes to warrant their approval for compliance

monitoring.

    Bromate. In the 1994 proposed rule, EPA discussed the fact that the

current version of EPA Method 300.0 was not sensitive enough to measure

bromate ion concentrations at the proposed MCL and requested comment on

modifications to EPA Method 300.0 to improve its sensitivity. In the

1997 NODA, EPA presented EPA Method 300.1 and requested comment on

replacing EPA Method 300.0 with EPA Method 300.1 for the analysis of

bromate.

    Commenters agreed that EPA Method 300.1 is a more sensitive method

than EPA Method 300.0 for low level bromate analysis and the majority

suggested that EPA Method 300.1 be the approved method for bromate

analysis. One commenter requested that interlaboratory round-robin

testing be conducted before EPA Method 300.1 is accepted for Stage 1

DBPR compliance monitoring. EPA considers interlaboratory round-robin

testing of EPA Method 300.1 to be unnecessary because this method is

essentially an improvement of EPA Method 300.0 which is already

approved. EPA Method 300.1 primarily makes use of a superior analytical

column to achieve increased sensitivity for bromate analysis. Moreover,

the efficacy of EPA Method 300.1 in a wide range of sample matrices is

demonstrated by the performance validation data contained in the

published method description. Based on a review of all the public

comments, EPA is approving EPA Method 300.1 for bromate analysis in

today's rule.

    Chlorite. EPA solicited comment in the 1997 DBPR NODA on approving

EPA Method 300.1, in addition to EPA Method 300.0, for compliance

analysis of chlorite. The majority of commenters on this issue favored

approval of both methods and today's rule establishes both for

determining compliance with the chlorite MCL.

    In the 1994 proposed rule, EPA requested comment on changing

monitoring requirements for chlorite to reflect concern about potential

acute health effects. Several commenters stated that daily monitoring

of chlorite would be feasible if an amperometric analytical method

could be used. Commenters suggested that daily amperometric analyses

for chlorite be conducted on samples taken from the entrance to the

distribution system, and that weekly or monthly analyses using ion

chromatography still be required as a check, because ion chromatography

is a more accurate analytical method. Commenters noted that daily

monitoring for chlorite would provide improved operational control of

plants and reduce the likelihood of systems incurring compliance

violations.

    Today's rule establishes amperometric titration (Standard Method

4500-ClO<INF>2</INF> E) for daily analyses of chlorite samples taken at

the entrance to the distribution system, along with monthly (or

quarterly if reduced, or additional as required), analyses by ion

chromatography (EPA Methods 300.0 and 300.1) of chlorite samples taken

from within the distribution system. EPA believes that the ion

chromatography method, rather than the amperometric method, should be

used for making chlorite compliance determinations in the distribution

system due to its greater accuracy. However, the amperometric method is

sufficient for the purposes of daily monitoring at the entrance to the

distribution system, which are to significantly aid in proper

operational control of a treatment plant and to indicate when

distribution system testing is appropriate. For this reason, only the

ion chromatographic methods (EPA Method 300.0 and 300.1), and not the

amperometric titration methods, are approved in today's rule for

determining compliance with the chlorite MCL.

    A minority of commenters on this issue suggested that the DPD

method (Standard Method 4500-ClO<INF>2</INF> D (APHA 1995)) be approved

for daily monitoring of chlorite ion levels. EPA has determined that

the accuracy and precision of the DPD method (Standard Method 4500-

ClO<INF>2</INF> D) in the measurement of chlorite are substantially

worse than with Standard Method 4500-ClO<INF>2</INF> E, and are

insufficient for this method to be used for daily monitoring of

chlorite. As a consequence, EPA has not approved the DPD method for

chlorite monitoring in today's rule.

    TOC. EPA received several comments on the 1994 proposal requesting

approval of Standard Method 5310 B for TOC compliance analysis.

Commenters stated that newer instrumentation could achieve a detection

limit of 0.5 mg/L TOC using this method. Following the publication of a

revised version of Method 5310 B in Standard Methods 19th Edition

Supplement (APHA 1996) which recognized the capacity of some combustion

based TOC analyzers to achieve detection limits below 1 mg/L, EPA

requested comment on approving Standard Method 5310 B, along with

Standard Methods 5310 C and 5310 D, for the analysis of TOC in the 1997

DBPR NODA.

    The majority of commenters on TOC analysis urged EPA to approve all

three methods. Commenters were concerned, though, that because these

three methods employ different processes to oxidize organic carbon to

carbon dioxide, results from different TOC analyzers could vary to a

degree that is of regulatory significance. Specifically, the efficiency

of oxidation of large organic particles or very large organic molecules

such as tannins, lignins, and humic acids may be lower with persulfate

based instruments (APHA 1996). Although available data comparing

different TOC methods is limited, one study observed a persulfate

catalytic oxidation technique to underestimate the TOC concentration

measured by a high temperature catalytic oxidation technique by 3-6% on

stream water and soil water samples (Kaplan, 1992). Standard Methods

recommends checking the oxidation efficiency of the instrument with

model compounds representative of the sample matrix, because many

factors can influence conversion of organic carbon to carbon dioxide

(APHA 1996).

    EPA believes that the potential regulatory impact of small

disparities in oxidation efficiencies between different TOC analyzers

is minor. Studies using PE samples indicate that for instruments

calibrated in accordance with the



[[Page 69421]]



procedures specified in Standard Methods (APHA, 1996), the magnitude of

measurement error due to analytical discrepancies between instruments

will typically be less than the measurement uncertainty attributed to a

particular instrument (EPA, 1994c). In addition, EPA anticipates that

most systems will use a consistent method for TOC analyses and that

this will assist in minimizing the importance of instrument bias. This

practice was suggested by several commenters.

    Commenters also suggested that EPA implement a formal certification

process for laboratories measuring TOC. Some commenters recommended

that EPA require a laboratory approval process for TOC measurements

under the Stage 1 DBPR that is similar to what is required under the

ICR. EPA requires that TOC analyses be conducted by a party approved by

EPA or the State but not that TOC measurements be subject to the same

laboratory certification procedures required for the analysis of DBPs.

However, today's rule contains QC requirements for TOC analyses which

are in addition to those in Standard Methods. These additional QC

procedures pertain to sample preservation and holding time, and have

been found to be effective for TOC analyses under the ICR.

    SUVA. In the 1997 DBPR NODA, EPA solicited comment on a range of

issues dealing with the determination of SUVA including: analytical

methods, sampling, sample preparation, filter types, pH, interferences

to UV, high turbidity waters, quality control, and other issues that

should be addressed. The Agency requested comment on approving Standard

Method 5910 B for measuring UV<INF>254</INF> and Standard Methods 5310

B, C, and D, for measuring DOC. In requesting comment on filtration,

EPA noted that filtration is necessary prior to both UV<INF>254</INF>

and DOC analyses in order to eliminate particulate matter and separate

the operationally defined dissolved organic matter (based on a 0.45

<greek-m>m-pore-diameter cut-off). However, filtration can also corrupt

samples through adsorption of carbonaceous material onto the filter or

its desorption from it (APHA 1996). In addition, EPA requested comment

on requiring that UV<INF>254</INF> and DOC analyses be measured from

the same sample filtrate.

    The majority of commenters on SUVA analytical methods recommended

that EPA approve Standard Methods 5310 B, C, and D, for DOC analysis

and Standard Method 5910 B for UV<INF>254</INF> analysis. EPA has

approved these methods in today's rule. In addition, commenters

stressed the importance of sample preparation, especially filtration,

in the measurement of DOC and observed that sufficient washing of

filters prior to filtration of samples is critical to preventing

contamination of the samples by organic carbon from the filters.

Several comments on the 1997 DBPR NODA expressed opposition to a

requirement that UV<INF>254</INF> and DOC analyses be made on the same

sample filtrate. Commenters stated that this is impractical because UV

analyses are often conducted at the treatment plant while DOC analyses

are typically run off-site. Commenters also noted that DOC samples

should be acid preserved whereas pH adjustment of samples for

UV<INF>254</INF> analysis is improper.

    Today's rule establishes that samples for DOC and UV<INF>254</INF>

analyses must be filtered through a 0.45 <greek-m>m-pore-diameter

filter. EPA does not have specific requirements on the type of filter

that is used, provided it has a 0.45 <greek-m>m pore-diameter, but will

provide guidance on this issue in the Guidance Manual for Enhanced

Coagulation. This manual will be available for public review after

promulgation of the Stage 1 DBPR. Today's rule addresses filter washing

prior to analysis by requiring that water passed through the filter

prior to filtration of the sample serve as the filtered blank. The

filtered blank must be analyzed using procedures identical to those

used for analysis of the samples and must meet the following criteria:

TOC < 0.5 mg/L. These criteria are the maximum allowable background

concentrations specified for these analyses under the ICR. In the

Guidance Manual for Enhanced Coagulation, EPA will furnish instructions

on sample handling and filter washing to assist systems in achieving

acceptable field reagent blanks.

    Filtration of samples for DOC analysis must be done prior to acid

preservation, as stipulated in today's rule. This is necessary because

acidification of the sample to pH < 2 can cause substantial

precipitation of dissolved organic species. Because biological activity

will rapidly alter the DOC of a sample that has not been preserved, EPA

requires that DOC samples be acidified to pH < 2.0 within 48 hours of

sampling. Consequently, filtration of DOC samples must be done within

48 hours in order to allow acid preservation within this time period.

The pH of UV<INF>254</INF> samples may not be adjusted. Today's rule

places a maximum holding time from sampling to analysis of 2 days for

UV<INF>254</INF> samples and 28 days for DOC samples. These holding

times are the same as those approved for ICR data collection.

    Because the filtration procedures for UV<INF>254</INF> and DOC

samples are largely identical, EPA anticipates that most systems will

find it economical when determining SUVA to filter one sample. The

filtrate would then be split into two portions, one of which would be

used for UV analysis while the other would be acid preserved and used

for DOC analysis. However, EPA has not included a requirement that the

DOC and UV<INF>254</INF> analyses used in the SUVA determination be

made on the same sample filtrate. Instead, EPA requires that DOC and

UV<INF>254</INF> samples used to determine a SUVA value must be taken

at the same time and at the same location.

    In the 1997 DBPR NODA, EPA also observed that because

disinfectants/oxidants (chlorine, ozone, chlorine dioxide, potassium

permanganate) typically reduce UV<INF>254</INF> without substantially

impacting DOC, raw water SUVA should be determined on water prior to

the application of disinfectants/oxidants. If disinfectants/oxidants

are applied in raw-water transmission lines upstream of the plant, then

raw water SUVA should be based on a sample collected upstream of the

point of disinfectant/oxidant addition. For determining settled-water

SUVA, if the plant applies disinfectants/oxidants prior to the settled

water sample tap, then settled-water SUVA should be determined in jar

testing. No commenters were opposed to these provisions and today's

rule requires that samples used for SUVA determinations be taken from

water prior to the addition of any oxidants/disinfectants.

    A few commenters stated that SUVA should not be subject to rigorous

analytical procedures because the application of SUVA in this rule is

based on a relationship which is largely empirical (i.e. correlations

between SUVA and TOC removal by coagulation). EPA recognizes the

empirical nature of this relationship and the variance it has displayed

in studies. Regulations, however, must address specific SUVA values if

SUVA is to serve as an alternative compliance parameter. For compliance

with these regulations to be meaningful, SUVA must be determined

accurately. Consequently, today's rule requires certain QC procedures

in the DOC and UV<INF>254</INF> analyses that are used to calculate

SUVA.

    Today's rule establishes the removal of 10 mg/L magnesium hardness

(as CaCO3) as an alternative performance criterion that systems

practicing enhanced softening can use to demonstrate compliance with

the treatment technique requirement for TOC removal. However, EPA did

not propose methods for the analysis of



[[Page 69422]]



magnesium in drinking water and therefore the final rule does not

contain any approved methods for magnesium. EPA expects to propose

magnesium analytical methods to be used for compliance monitoring under

the Stage 1 DBPR by the end of 1998.

4. Performance Based Measurement Systems

    On October 6, 1997, EPA published a Document of the Agency's intent

to implement a Performance Based Measurement System (PBMS) in all of

its programs to the extent feasible (EPA, 1997f). The Agency is

currently determining the specifics steps necessary to implement PBMS

in its programs and preparing an implementation plan. Final decisions

have not yet been made concerning the implementation of PBMS in

drinking water programs. However, EPA is currently evaluating what

relevant performance characteristics should be specified for monitoring

methods used in the drinking water programs under a PBMS approach to

ensure adequate data quality. EPA would then specify performance

requirements in its regulations to ensure that any method used for

determination of a regulated analyte is at least equivalent to the

performance achieved by other currently approved methods. EPA expects

to publish its PBMS implementation strategy for water programs in the

Federal Register by the end of calendar year 1998.

    Once EPA has made its final determinations regarding implementation

of PBMS in programs under the Safe Drinking Water Act, EPA would

incorporate specific provisions of PBMS into its regulations, which may

include specification of the performance characteristics for

measurement of regulated contaminants in the drinking water program

regulations.



H. Monitoring Requirements



1. Today's Rule

    Today's rule establishes monitoring requirements to support

implementation of the enhanced coagulation and enhanced softening

treatment technique, implementation of new MCLs for TTHM, HAA5,

bromate, and chlorite, and implementation of MRDLs for chlorine,

chloramines, and chlorine dioxide. Monitoring for DBPs, disinfectant

residuals, and TOC must be conducted during normal operating

conditions. Failure to monitor in accordance with the monitoring plan

is a monitoring violation. Where compliance is based on a running

annual average of monthly or quarterly samples or averages and the

system's failure to monitor makes it impossible to determine compliance

with MCLs or MRDLs, this failure to monitor will be treated as a

violation.

    Tables III-3 and III-4 below summarize routine and reduced

monitoring requirements of today's rule.



                                                    Table III-3.--Routine Monitoring Requirements \1\

--------------------------------------------------------------------------------------------------------------------------------------------------------

                                                              Large surface systems  Small surface systems    Large ground water     Small ground water

      Requirement (reference)         Location for sampling            \2\                    \2\                systems \3\            systems \3\

--------------------------------------------------------------------------------------------------------------------------------------------------------

TOC and Alkalinity (141.132(d)(1)).  Source Water \4\......  1sample/month/plant     1 sample/month/        NA...................  NA.

                                                              \3\.                    plant\3\.

                                     Only required for

                                      plants with

                                      conventional

                                      filtration treatment.

TTHMs and HAA5 (141.132(b)(1)(i))..  25% in dist sys at max  4/plant/quarter.......  1/plant/quarter\5\...  1/plant/quarter \6\..  1/plant/year <SUP>5,6

                                      res time, 75% at dist

                                      sys representative

                                      locations.

                                                                                     at maximum residence   at maximum residence   at maximum residence

                                                                                      time.                  time.                  time.

                                                                                     if pop.<500, then 1/                          during warmest month.

                                                                                      plant/yr \8\.

                                                                                     during warmest month.

Bromate \7\ (141.132(b)(3)(i)).....  Dist sys entrance       1/month/trt plant       1/month/trt plant      1/month/trt plant      1/month/trt plant

                                      point.                  using O<INF>3.               using O<INF>3.              using O<INF>3.              using O<INF>3.

Chlorite\8\ (daily)                  Dist sys entrance       Daily/trt plant using   Daily/trt plant using  Daily/trt/plant using

(141.132(b)(2)(i)(A)).               point.                  CIO<INF>2.                   CIO<INF>2.                  CIO<INF>2.

Chlorite\8\ (monthly)                Dist sys: 1 near first  3 sample set/month....  3 sample set/month...  3 sample set/month...  3 sample set/month.

141.132(b)(2)(i)(B)).                cust, 1 in dist sys

                                      middle, 1 at max res

                                      time.

Chlorine and chloramines             Same points as total    Same times as total     Same times as total    Same times as total    Same times as total

(141.132(c)(1)(i)).                  coliform in TCR.        coliform in TCR.        coliform in TCR.       coliform in TCR.       coliform in TCR.

Chlorine dioxide\8\                  Dist sys entrance        Daily/trt plant using   Daily/trt plant        Daily/trt plant        Daily/trt plant

(141.132(c)(2)(i)).                  point.                  CIO<INF>2.                   using CIO<INF>2.            using CIO<INF>2.            using CIO.

--------------------------------------------------------------------------------------------------------------------------------------------------------

\1\ Samples must be taken during representative operating conditions. Provisions for reduced monitoring shown elsewhere.

\2\ Large surface (subpart H) systems serve 10,000 or more persons. Small surface (subpart H) systems serve fewer than 10,000 persons.

\3\ Large systems using ground water not under the direct influence of surface water serve 10,000 or more persons. Small systems using ground water not

  under the direct influence of surface water serve fewer than 10,000 persons.

\4\ Subpart H systems which use conventional filtration treatment (defined in section 141.2) must monitor 1) source water TOC prior to any treatment and

  2) treated TOC at the same time; these two samples are called paired samples. Systems must take a source water alkalinity sample at the same time.

\5\ If the annual monitoring result exceeds the MCL, the system must increase monitoring frequency to 1/plant/quarter. Compliance determinations will be

  based on the running annual average of quarterly monitoring results.



[[Page 69423]]





\6\ Multiple wells drawing water from a single aquifer may, with State approval, be considered one treatment plant for determining the minimum number of

  samples.

\7\ Only required for systems using ozone for oxidation or disinfection.

\8\ Only required for systems using chlorine dioxide for oxidation or disinfection. Additional chlorite monitoring required if daily sample exceeds MCL.

  Additional chlorine dioxide monitoring requirements apply if any chlorine dioxide sample exceeds the MRDL.





                                Table III-4.--Reduced Monitoring Requirements \1\

----------------------------------------------------------------------------------------------------------------

                                         Location for reduced    Reduced monitoring frequency and prerequisites

       Requirement (reference)                 sampling                                \2\

----------------------------------------------------------------------------------------------------------------

TOC and Alkalinity (141.132(d)(2))...  Paired samples \3\.....  Subpart H systems-reduced to 1 paired sample/

                                                                 plant/quarter if 1) avg TOC < 2.0 mg/l for 2

                                                                 years or 2) avg TOC < 1.0 mg/l for 1 year.

TTHMs and HAA5s (141.132(b)(1)(ii))..  In dist sys at point     Monitoring cannot be reduced if subpart H system

                                        with max res time.       source water TOC > 4.0 mg/l.

                                                                Subpart H systems serving 10,000 or more-reduced

                                                                 to 1/plant/qtr if 1) system has completed at

                                                                 least 1 yr of routine monitoring and 2) both

                                                                 TTHM and HAA5 running annual averages are no

                                                                 more than 40 <greek-m>g/l and 30 <greek-m>g/l,

                                                                 respectively.

                                                                Subpart H systems serving <10,000 and ground

                                                                 water systems \4\ serving 10,000 or more-

                                                                 reduced to 1/plant/yr if 1) system has

                                                                 completed at least 1 yr of routine monitoring

                                                                 and 2) both TTHM and HAA5 running annual

                                                                 averages are no more than 40 <greek-m>g/l and

                                                                 30 <greek-m>g/l, respectively. Samples must be

                                                                 taken during month of warmest water

                                                                 temperature. Subpart H systems serving <500 may

                                                                 not reduce monitoring to less than 1/plant/yr.

                                                                Groundwater systems \6\ serving<10,000-reduced

                                                                 to 1/plant/3yr if 1) system has completed at

                                                                 least 2 yr of routine monitoring and both TTHM

                                                                 and HAA5 running annual averages are no more

                                                                 than 40 <greek-m>g/l and 30 <greek-m>g/l,

                                                                 respectively or 2) system has completed at

                                                                 least 1 yr of routine monitoring and both TTHM

                                                                 and HAA5 annual samples are no more than 20

                                                                 <greek-m>g/l and 15 <greek-m>g/l, respectively.

                                                                 Samples must be taken during month of warmest

                                                                 water temperature.

Bromate \5\ (141.132(b)(3)(ii))......  Dist sys entrance point  1/qtr/trt plant using O<INF>3, if system demonstrates

                                                                 1) avg raw water bromide <0.05 mg/l (based on

                                                                 annual avg of monthly samples).

Chlorite \6\ (141.132(b)(2)(iii))....  Dist sys: 1 near first   Systems may reduce routine distribution system

                                        cust, 1 in dist sys      monitoring from monthly to quarterly if the

                                        middle, 1 at max res     chlorite concentration in all samples taken in

                                        time.                    the distribution system is below 1.0 mg/L for a

                                                                 period of one year; 3 samples per quarter.

Chlorine, chlorine dioxide \6\,        NA.....................  Monitoring may not be reduced.

chloramines (141.132(c)(2)(ii) and

(c)(2)(iii).

----------------------------------------------------------------------------------------------------------------

\1\ Samples must be taken during representative operating conditions. Provisions for routine monitoring shown

  elsewhere.

\2\ Requirements for cancellation of reduced monitoring are found in the regulation.

\3\ Subpart H systems which use conventional filtration treatment (defined in Section 141.2) must monitor 1)

  source water TOC prior to any treatment and 2) treated TOC before continuous disinfection (except that systems

  using ozone followed by biological filtration may sample after biological filtration) at the same time; these

  two samples are called paired samples.

\4\ Multiple wells drawing water from a single aquifer may, with State approval, be considered one treatment

  plant for determining the minimum number of samples.

\5\ Only required for systems using ozone for oxidation or disinfection.

\6\ Only required for systems using chlorine dioxide for oxidation or disinfection.



    The formation rate of DBPs is affected by type and amount of

disinfectant used, water temperature, pH, amount and type of precursor

material in the water, and the length of time that water remains in the

treatment and distribution systems. For this reason, today's rule

specifies the points in the distribution system (and, in some cases,

the time) where samples must be taken. For purposes of this regulation,

multiple wells drawing raw water from a single aquifer may, with State

approval, be considered one plant for determining the minimum number of

samples.

    TTHM and HAA5. Any system may take samples in excess of the

required frequency. In such cases, at least 25 percent of all samples

collected each quarter must be taken at locations within the

distribution system that represent the maximum residence time of the

water in the system. The remaining samples must be taken at locations

representative of at least average residence time in the distribution

system.

    Subpart H Systems Serving 10,000 or More People. Routine

Monitoring: CWSs and NTNCWSs using surface water (or ground water under

direct influence of surface water) (Subpart H systems) that treat their

water with a chemical disinfectant and serve 10,000 or more people must

routinely take four water samples each quarter for both TTHMs and HAA5

for each treatment plant in the system. At least 25 percent of the

samples must be taken at the point of maximum residence time in the

distribution system. The remaining samples must be taken at

representative points in the distribution system. This monitoring

frequency is the same as the frequency required under the current TTHM

rule (Sec. 141.30).

    Reduced Monitoring: To qualify for reduced monitoring, systems must

meet certain prerequisites (see Figure III-1). Systems eligible for

reduced monitoring may reduce the monitoring frequency for TTHMs and

HAA5 to one sample per treatment plant per quarter. Systems on a

reduced monitoring schedule may remain on that reduced schedule as long

as the average of all samples taken in the year is no more than 0.060

mg/L for TTHM and 0.045 mg/L for HAA5. Systems that do not meet these

levels must revert to routine monitoring in the quarter immediately

following the quarter in which the system exceeded 0.060 mg/L for TTHM

or 0.045 mg/L for HAA5. Additionally, the State may return a system to

routine monitoring at the State's discretion.



[[Page 69424]]







Figure III-1.--Eligibility for Reduced TTHM and HAA5 Monitoring: Ground

    Water Systems Serving 10,000 or More People and Subpart H Systems

                       Serving 500 or More People

------------------------------------------------------------------------



-------------------------------------------------------------------------

Ground water systems serving 10,000 or more people, and Subpart H

systems serving 500 or more people, may reduce monitoring of TTHMs and

HAA5 if they meet all of the following conditions:

    --The annual average for TTHMs is no more than 0.040 mg/L.

    --The annual average for HAA5 is no more than 0.030 mg/L.

    --At least one year of routine monitoring has been completed.

    --Annual average source water TOC level is no more than 4.0 mg/L

     prior to treatment (applies to Subpart H systems only).

------------------------------------------------------------------------



    Compliance Determination: A public water system (PWS) is in

compliance with the MCL when the running annual arithmetic average of

quarterly averages of all samples, computed quarterly, is less than or

equal to the MCL. If the running annual average computed for any

quarter exceeds the MCL, the system is out of compliance.

    Subpart H Systems Serving 500 to 9,999 People. Routine Monitoring:

Systems are required to take one water sample each quarter for each

treatment plant in the system. Samples must be taken at the point of

maximum residence time in the distribution system.

    Reduced Monitoring: To qualify for reduced monitoring, systems must

meet certain prerequisites (see Figure III-1). Systems eligible for

reduced monitoring may reduce the monitoring frequency for TTHMs and

HAA5 to one sample per treatment plant per year. Sample must be taken

at a distribution system location reflecting maximum residence time and

during the month of warmest water temperature. Systems on a reduced

monitoring schedule may remain on that reduced schedule as long as the

average of all samples taken in the year is no more than 0.060 mg/L for

TTHM and 0.045 mg/L for HAA5. Systems that do not meet these levels

must revert to routine monitoring in the quarter immediately following

the quarter in which the system exceeded 0.060 mg/L for TTHM or 0.045

mg/L for HAA5. Additionally, the State may return a system to routine

monitoring at the State's discretion.

    Compliance Determination: A PWS is in compliance with the MCL for

TTHM and HAA5 when the annual average of all samples, taken that year,

is less than or equal to the MCL. If the average for these samples

exceeds the MCL, the system is out of compliance.

    Subpart H Systems Serving Fewer than 500 People. Routine

Monitoring: Subpart H systems serving fewer than 500 people are

required to take one sample per year for each treatment plant in the

system. The sample must be taken at the point of maximum residence time

in the distribution system during the month of warmest water

temperature. If the annual sample exceeds the MCL, the system must

increase monitoring to one sample per treatment plant per quarter,

taken at the point of maximum residence time in the distribution

system.

    Reduced Monitoring: These systems may not reduce monitoring.

Systems on increased monitoring may return to routine monitoring if the

annual average of quarterly samples is no more than 0.060 mg/L for TTHM

and 0.045 mg/L for HAA5.

    Compliance Determination: A PWS is in compliance when the annual

sample (or average of annual samples, if additional sampling is

conducted) is less than or equal to the MCL. If the annual sample

exceeds the MCL, the system must increase monitoring to one sample per

treatment plant per quarter. If the running annual average of the

quarterly samples then exceeds the MCL, the system is out of

compliance.

    Ground Water Systems Serving 10,000 or More People. Routine

Monitoring: CWSs and NTNCWSs using only ground water sources not under

the direct influence of surface water that treat their water with a

chemical disinfectant and serve 10,000 or more people are required to

take one water sample each quarter for each treatment plant in the

system. Samples must be taken at points that represent the maximum

residence time in the distribution system.

    Reduced Monitoring: To qualify for reduced monitoring, systems must

meet certain prerequisites (see Figure III-1). Systems eligible for

reduced monitoring may reduce the monitoring frequency to one sample

per treatment plant per year. Sample must be taken at a distribution

system location reflecting maximum residence time and during the month

of warmest water temperature. Systems on a reduced monitoring schedule

may remain on that reduced schedule as long as the average of all

samples taken in the year is no more than 0.060 mg/L for TTHM and 0.045

mg/L for HAA5. Systems that do not meet these levels must revert to

routine monitoring in the quarter immediately following the quarter in

which the system exceeded 0.060 mg/L for TTHM or 0.045 mg/L for HAA5.

Additionally, the State may return a system to routine monitoring at

the State's discretion.

    Compliance Determination: A PWS is in compliance with the MCL when

the running arithmetic annual average of quarterly averages of all

samples, computed quarterly, is less than or equal to the MCL. If the

running annual average for any quarter exceeds the MCL, the system is

out of compliance.

    Ground Water Systems Serving Fewer than 10,000 People Routine

Monitoring: CWSs and NTNCWSs using only ground water sources not under

the direct influence of surface water that treat their water with a

chemical disinfectant and serve fewer than 10,000 people are required

to sample once per year for each treatment plant in the system. The

sample must be taken at the point of maximum residence time in the

distribution system during the month of warmest water temperature. If

the sample (or the average of annual samples if more than one sample is

taken) exceeds the MCL, the system must increase monitoring to one

sample per treatment plant per quarter.

    Reduced Monitoring: To qualify for reduced monitoring, systems must

meet certain prerequisites (see Figure III-2). Systems eligible for

reduced monitoring may reduce the monitoring frequency for TTHMs and

HAA5 to one sample per three-year monitoring cycle. Sample must be

taken at a distribution system location reflecting maximum residence

time and during the month of warmest water temperature. Systems on a

reduced monitoring schedule may remain on that reduced schedule as long

as the average of all samples taken in the year is no more than 0.060

mg/L for TTHM and 0.045 mg/L for HAA5. Systems that do not meet these

levels must resume routine monitoring. Systems on increased monitoring

may return to routine monitoring if the annual average of quarterly

samples is no more than 0.060 mg/L for TTHM and 0.045 mg/L for HAA5.

    Compliance Determination: A PWS is in compliance when the annual

sample (or average of annual samples) is less than or equal to the MCL.



[[Page 69425]]







Figure III-2.--Eligibility for Reduced TTHM and HAA5 Monitoring: Ground

             Water Systems Serving Fewer than 10,000 People

------------------------------------------------------------------------



-------------------------------------------------------------------------

Systems using ground water not under the direct influence of surface

water that serve fewer than 10,000 people may reduce monitoring for

TTHMs and HAA5 if they meet either of the following conditions:

1. The average of two consecutive annual samples for TTHMs is no more

than 0.040 mg/L, the average of two consecutive annual samples for HAA5

is no more than 0.030 mg/L, and at least two years of routine

monitoring has been completed.

2. The annual sample for TTHMs is no more than 0.020 mg/L, the annual

sample for HAA5 is no more than 0.015 mg/L, and at least one year of

routine monitoring has been completed.

------------------------------------------------------------------------



    Chlorite. Routine Monitoring: CWSs and NTNCWSs using chlorine

dioxide for disinfection or oxidation are required to conduct sampling

for chlorite both daily at the entrance to the distribution system and

monthly within the distribution system. Additional distribution system

monitoring may be required, and distribution system monitoring may be

reduced if certain conditions are met. This monitoring is described

below.

    Routine Monthly Monitoring--Systems are required to take a three

sample set each month in the distribution system. One sample must be

taken at each of the following locations: (1) as close as possible to

the first customer, (2) in a location representative of average

residence time, and (3) as close as possible to the end of the

distribution system (reflecting maximum residence time in the

distribution system). As described elsewhere in this document, all

samples taken in the distribution system must be analyzed by ion

chromatography (Methods 300.0 and 300.1).

    Routine Daily Monitoring--Systems must take one sample each day at

the entrance to the distribution system. As described elsewhere in this

document (section III.G), samples taken at the distribution system

entrance may be analyzed by amperometric titration (Method 4500-

ClO<INF>2</INF> E). If the chlorite MCL is exceeded at the entrance to

the distribution system, the system is not out of compliance. However,

the system must carry out addition monitoring as described in the

following paragraph.

    Additional Monitoring: On any day when the chlorite concentration

measured at the entrance to the distribution system exceeds the

chlorite MCL (1.0 mg/L), the system is required to take a three sample

set in the distribution system on the following day, at the locations

specified for routine monthly monitoring. If the system is required to

conduct distribution system monitoring as a result of having exceeded

the chlorite MCL at the entrance to the distribution system, and the

average of the three samples taken in the distribution system is below

1.0 mg/L, the system will have satisfied its routine monthly monitoring

requirement for that month. Further distribution system monitoring will

not be required in that month unless the chlorite concentration at the

entrance to the distribution system again exceeds 1.0 mg/L.

    Reduced Monitoring: Systems may reduce routine distribution system

monitoring for chlorite from monthly to quarterly if the chlorite

concentration in all samples taken in the distribution system is below

1.0 mg/L for a period of one year and the system has not been required

to conduct any additional monitoring. Systems that qualify for reduced

monitoring must continue to conduct daily monitoring at the entrance to

the distribution system. If the chlorite concentration at the entrance

to the distribution system exceeds 1.0 mg/L, the system must resume

routine monthly monitoring.

    Compliance Determination: A PWS is out of compliance with the

chlorite MCL when the arithmetic average concentration of any three

sample set taken in the distribution system is greater than 1.0 mg/L.

    Bromate. Routine Monitoring: CWSs and NTNCWSs using ozone for

disinfection or oxidation are required to take at least one sample per

month for each treatment plant in the system using ozone. The sample

must be taken at the entrance to the distribution system when the

ozonation system is operating under normal conditions.

    Reduced Monitoring: Systems may reduce monitoring from monthly to

once per quarter if the system demonstrates that the annual average raw

water bromide concentration is less than 0.05 mg/L, based upon monthly

measurements for one year.

    Compliance Determination: A PWS is in compliance if the running

annual arithmetic average of samples, computed quarterly, is less than

or equal to the MCL.

    Chlorine. Routine Monitoring: As a minimum, CWSs and NTNCWSs must

measure the residual disinfectant level (as either free chlorine or

total chlorine) at the same points in the distribution system and at

the same time as total coliforms, as specified in Sec. 141.21. Subpart

H systems may use the results of residual disinfectant concentration

sampling done under the SWTR (Sec. 141.74(b)(6)(i) for unfiltered

systems, Sec. 141.74(c)(3)(i) for systems that filter) in lieu of

taking separate samples.

    Reduced Monitoring: Monitoring for chlorine may not be reduced.

    Compliance Determination: A PWS is in compliance with the MRDL when

the running annual arithmetic average of monthly averages of all

samples, computed quarterly, is less than or equal to the MRDL.

Notwithstanding the MRDL, operators may increase residual chlorine

levels in the distribution system to a level and for a time necessary

to protect public health to address specific microbiological

contamination problems (e.g., including distribution line breaks, storm

runoff events, source water contamination, or cross-connections).

    Chloramines. Routine Monitoring: As a minimum, CWSs and NTNCWSs

must measure the residual disinfectant level (as either total chlorine

or combined chlorine) at the same points in the distribution system and

at the same time as total coliforms, as specified in Sec. 141.21.

Subpart H systems may use the results of residual disinfectant

concentration sampling done under the SWTR (Sec. 141.74(b)(6) for

unfiltered systems, Sec. 141.74(c)(3) for systems that filter) in lieu

of taking separate samples.

    Reduced Monitoring: Monitoring for chloramines may not be reduced.

    Compliance Determination: A PWS is in compliance with the MRDL when

the running annual arithmetic average of monthly averages of all

samples, computed quarterly, is less than or equal to the MRDL.

Notwithstanding the MRDL, operators may increase residual chloramine

levels in the distribution system to a level and for a time necessary

to protect public health to address specific microbiological

contamination problems (e.g., including distribution line breaks, storm

runoff events, source water contamination, or cross-connections).

    Chlorine Dioxide Routine Monitoring: CWSs, NTNCWSs, and TNCWSs must

monitor for chlorine dioxide only if chlorine dioxide is used by the

system for disinfection or oxidation. If monitoring is required,

systems must take daily samples at the entrance to the



[[Page 69426]]



distribution system. If the MRDL (0.8 mg/L) is exceeded, the system

must conduct additional monitoring.

    Additional Monitoring: If any daily sample taken at the entrance to

the distribution system exceeds the MRDL, the system is required to

take three additional samples in the distribution system on the next

day. Samples must be taken at the following locations.

    Systems using chlorine as a residual disinfectant and operating

booster chlorination stations after the first customer--These systems

must take three samples in the distribution system: one as close as

possible to the first customer, one in a location representative of

average residence time, and one as close as possible to the end of the

distribution system (reflecting maximum residence time in the

distribution system).

    Systems using chlorine dioxide or chloramines as a residual

disinfectant or chlorine as a residual disinfectant and not operating

booster chlorination stations after the first customer--These systems

must take three samples in the distribution system as close as possible

to the first customer at intervals of not less than six hours.

    Reduced Monitoring: Monitoring for chlorine dioxide may not be

reduced.

    Compliance Determination: Acute violations--If any daily sample

taken at the entrance to the distribution system exceeds the MRDL and

if, on the following day, one or more of the three samples taken in the

distribution system exceeds the MRDL, the system will be in acute

violation of the MRDL and must issue the required acute public

notification. Failure to monitor in the distribution system on the day

following an exceedance of the chlorine dioxide MRDL shall also be

considered an acute MRDL violation.

    Nonacute violations--If any two consecutive daily samples taken at

the entrance to the distribution system exceed the MRDL, but none of

the samples taken in the distribution system exceed the MRDL, the

system will be in nonacute violation of the MRDL. Failure to monitor at

the entrance to the distribution system on the day following an

exceedance of the chlorine dioxide MRDL shall also be considered a

nonacute MRDL violation.

    Important Note: Unlike chlorine and chloramines, the MRDL for

chlorine dioxide may not be exceeded for short periods of time to

address specific microbiological contamination problems.

    TOC. Routine Monitoring: CWSs and NTNCWSs which use conventional

filtration treatment must monitor each treatment plant water source for

TOC on a monthly basis, with samples taken in both the source water

prior to any treatment and in the treated water no later than the point

of combined filter effluent turbidity monitoring. At the same time,

systems must monitor for source water alkalinity.

    Reduced Monitoring: Subpart H systems with an average treated water

TOC of less than 2.0 mg/L for two consecutive years, or less than 1.0

mg/L for one year, may reduce monitoring for both TOC and alkalinity to

one paired sample per plant per quarter.

    Compliance Determination: Compliance criteria for TOC are dependent

upon a variety of factors and is discussed elsewhere in this rule.

2. Background and Analysis

    The monitoring requirements in today's rule are the same as those

in the 1994 proposed rule, with the exception of requirements for

bromide monitoring and chlorite.

    Bromide Monitoring for Reduced Bromate Monitoring. The 1994

proposal included a provision for reduced bromate monitoring for

utilities with source water bromide concentrations less than 0.05 mg/L.

EPA believes there is a very small likelihood that systems using ozone

will exceed the bromate MCL if source water bromide concentrations are

below this level. The provision did not specify a bromide monitoring

frequency, however. Today's rule allows utilities to reduce bromate

monitoring from monthly to once per quarter if the system demonstrates,

based on representative monthly samples over the course of a year, that

the average raw water bromide concentration is less than 0.05 mg/L.

    Chlorite Monitoring. The proposed rule required treatment plants

using chlorine dioxide to monitor for chlorite ion by taking a three

sample set in the distribution system, once per month, and to analyze

these samples using ion chromatography. However, the proposal states

that after the Negotiating Committee had agreed to the above monitoring

scheme for chlorite at its last meeting in June, 1993, EPA's Reference

Dose Committee met and determined a different toxicological endpoint

for chlorite, based on the identification of neurobehavioral effects.

In light of this finding, EPA asserted that it did not believe the

proposed monthly monitoring requirement for chlorite was sufficiently

protective of public health. Following the proposed rule, EPA acquired

additional information on chlorite toxicity, including the results of a

two-generation study sponsored by the CMA. This additional information,

discussed elsewhere in this document (III.A.7), supported EPA's finding

of neurobehavioral health effects resulting from chlorite, along with

the rationale for daily monitoring at the entrance to the distribution

system as a trigger for further compliance monitoring in the

distribution system.



3. Summary of Comments



    TOC. Many commenters expressed confusion regarding the raw and

finished water TOC monitoring scheme and their relationship to

compliance calculations. Commenters noted, correctly, that changes in

alkalinity and TOC level can move the utility to a different box of the

TOC removal matrix, and questioned whether this would affect requisite

monitoring. As in the proposal, moving to a different box of the matrix

will not affect monitoring requirements. Utilities are required to take

a minimum of one paired (raw and finished water) TOC sample per month.

Commenters were also concerned that the TOC monitoring provisions would

limit their ability to take additional TOC samples for operational

control. This concern is unfounded; EPA recommends in the Enhanced

Coagulation and Enhanced Precipitative Softening Guidance Manual that

utilities take as many TOC samples as necessary to maintain proper

operational control. EPA also recommends that TOC compliance samples,

as opposed to operational samples, be taken on a constant schedule or

be identified one month prior to the samples being taken. This will

allow utilities to take numerous operational samples and still provide

for unbiased compliance sampling. Systems may use their sampling plans

for this purpose.

    Chlorite. In the proposal, EPA solicited comment on changing the

frequency and location of chlorite monitoring in consideration of

potential acute health effects. Commenters stated that daily monitoring

of chlorite would be feasible if amperometric titration were allowed as

an analytical method. Commenters recommended that daily amperometric

analyses for chlorite be conducted on samples taken from the entrance

to the distribution system, and that weekly or monthly analyses using

ion chromatography still be required as a check since ion

chromatography is a more accurate analytical method. Several comments

stated that daily monitoring for chlorite would improve operational

control of plants and decrease the probability of a PWS exceeding the

chlorite MCL in the distribution system. However, commenters requested

that if daily monitoring for chlorite were to be



[[Page 69427]]



required, a provision for reduced chlorite monitoring be included as

well.

    In response to these comments, today's rule requires treatment

plants using chlorine dioxide to conduct daily monitoring for chlorite

by taking one sample at the entrance to the distribution system. This

sample may be measured using amperometric titration (Standard Method

4500-ClO <INF>2</INF> E). Treatment plants are also required to take a

three sample set from the distribution system once per month, as was

proposed in 1994. In addition, today's rule requires that on any day

that the concentration of chlorite measured at the distribution system

entrance exceeds the MCL, the treatment plant must take a three sample

set in the distribution system on the following day. All samples taken

in the distribution system must be analyzed by ion chromatography

(Method 300.0 or 300.1).

    EPA recommends that treatment plants keep chlorite levels below 1.0

mg/L and believes that if treatment plants exceed the MCL in finished

water, immediate distribution system testing is warranted to ensure

that chlorite levels are below 1.0 mg/L. EPA has not, however, changed

the compliance determination for chlorite from the 1994 proposed rule.

Compliance is still based on the average of three sample sets taken in

the distribution system. The results of daily monitoring do not serve

as a compliance violation; rather, they can only trigger immediate

distribution system monitoring. Moreover, if the treatment plant is

required to take distribution system samples by the results of daily

monitoring and the average chlorite concentration in the three

distribution system samples is below the MCL, then that sampling will

meet the treatment plant's requirement for routine monthly monitoring

in the distribution system for that month. Today's rule also includes a

provision for reduced chlorite monitoring. Treatment plants may reduce

routine distribution system monitoring for chlorite from monthly to

quarterly if the chlorite concentration in all samples both at the

entrance to the distribution system and within the distribution system

are below 1.0 mg/L for a period of one year.

    In summary, after review of all public comments and associated

data, EPA believes that these provisions for chlorite monitoring will

be both feasible for treatment plants and provide a level of protection

to public health commensurate with the toxic effects associated with

chlorite.



I. Compliance Schedules



1. Today's Rule

    Today's action establishes revised compliance deadlines for States

to adopt and for public water systems to implement the requirements in

this rulemaking. Central to the determination of these deadlines are

the principles of simultaneous compliance between the Stage 1 DBPR and

the corresponding rules (Interim Enhanced Surface Water Treatment Rule,

Long Term Enhanced Surface Water Treatment Rule, and Ground Water Rule)

to ensure continued microbial protection, and minimization of risk-risk

tradeoffs. These deadlines also reflect new legislative provisions

enacted as part of 1996 SDWA amendments. Section 1412 (b)(10) of the

SDWA as amended provides PWSs must comply with new regulatory

requirements 36 months after promulgation (unless EPA or a State

determines that an earlier time is practicable or that additional time

up to two years is necessary for capital improvements). In addition,

Section 1413(a)(1) provides that States have 24 instead of the previous

18 months from promulgation to adopt new drinking water standards.

    Applying the 1996 SDWA Amendments to today's action, this

rulemaking provides that States have two years from promulgation to

adopt and implement the requirements of this regulation. Simultaneous

compliance will be achieved as follows.

    Subpart H water systems covered by today's rule that serve a

population of 10,000 or more generally have three years from

promulgation to comply with all requirements of this rule. In cases

where capital improvements are needed to comply with the rule, States

may grant such systems up to an additional two years to comply. These

deadlines were consistent with those for the IESWTR.

    Subpart H systems that serve a population of less than 10,000 and

all ground water systems will be required to comply with applicable

Stage 1 DBPR requirements within five years from promulgation. Since

the Long Term Enhanced Surface Water Treatment Rule (LT1) requirements

that apply to systems under 10,000 and the Ground Water Rule are

scheduled to be promulgated two years after today's rule or in November

2000, the net result of this staggered deadline is that these systems

will be required to comply with both Stage 1 DBPR and LT1/GWR

requirements three years after promulgation of LT1/GWR at the same end

date of November 2003. For reasons discussed in more detail below, EPA

believes this is both consistent with the requirements of section

1412(b)(10) as well as with legislative history affirming the Reg. Neg.

objectives of simultaneous compliance and minimization of risk-risk

tradeoff.

2. Background and Analysis

    The background, factors, and competing concerns that EPA considered

in developing the compliance deadlines in today's rule are explained in

detail in both the Agency's IESWTR and Stage 1 DBPR November 1997

NODAs. As explained in those NODAs, EPA identified four options to

implement the requirements of the 1996 SDWA Amendments. The

requirements outlined above reflect the fourth option that EPA

requested comment upon in November 1997.

    By way of background, the SDWA 1996 Amendments affirmed several key

principles underlying the M-DBP compliance strategy developed by EPA

and stakeholders as part of the 1992 regulatory negotiation process.

First, under Section 1412(b)(5)(A), Congress recognized the critical

importance of addressing risk/risk tradeoffs in establishing drinking

water standards and gave EPA the authority to take such risks into

consideration in setting MCL or treatment technique requirements. The

technical concerns and policy objectives underlying M/DBP risk/risk

tradeoffs are referred to in the initial sections of today's rule and

have remained a key consideration in EPA's development of appropriate

compliance requirements. Second, Congress explicitly adopted the phased

M-DBP regulatory development schedule developed by the Negotiating

Committee. Section 1412(b)(2)(C) requires that the M/DBP standard

setting intervals laid out in EPA's proposed ICR rule be maintained

even if promulgation of one of the M-DBPRs is delayed. As explained in

the 1997 NODA, this phased or staggered regulatory schedule was

specifically designed as a tool to minimize risk/risk tradeoff. A

central component of this approach was the concept of ``simultaneous

compliance'', which provides that a PWS must comply with new microbial

and DBP requirements at the same time to assure that in meeting a set

of new requirements in one area, a facility does not inadvertently

increase the risk (i.e., the risk ``tradeoff'') in the other area.

    A complicating factor that EPA took into account in developing

today's deadlines is that the SDWA 1996 Amendments changed two

statutory provisions that elements of the 1992



[[Page 69428]]



Negotiated Rulemaking Agreement were based upon. The 1994 Stage 1 DBPR

and ICR proposals provided that 18 months after promulgation large PWS

would comply with the rules and States would adopt and implement the

new requirements. As noted above, Section 1412(b)(10) of the SDWA as

amended now provides that drinking water rules shall become effective

36 months after promulgation (unless the Administrator determines that

an earlier time is practicable or that additional time for capital

improvements is necessary--up to two years). In addition, Section

1413(a)(1) now provides that States have 24 instead of the previous 18

months to adopt new drinking water standards that have been promulgated

by EPA.

    Today's compliance deadline requirements reflect the principle of

simultaneous compliance and the concern with risk/risk tradeoffs.

Subpart H systems serving a population of at least 10,000 will be

required to comply with the key provisions of this rule on the same

schedule as they will be required to comply with the parallel

requirements of the accompanying IESWTR that is also included in

today's Federal Register.

    With regard to subpart H systems serving fewer than 10,000, EPA

believes that providing a five year compliance period under Stage 1

DBPR is appropriate and warranted under section 1412(b)(10), which

expressly allows five years where necessary for capital improvements.

As discussed in more detail in the 1997 IESWTR NODA, capital

improvements require, of necessity, preliminary planning and

evaluation. An essential prerequisite of such planning is a clear

understanding of final compliance requirements that must be met. In the

case of the staggered M/DBP regulatory schedule established as part of

the 1996 SDWA Amendments, LT1 microbial requirements for systems under

10,000 are required to be promulgated two years after the final Stage 1

DBPR. As a result, small systems will not even know what their final

combined compliance obligations are until promulgation of the LT 1

rule. Thus, an additional two year period reflecting the two year Stage

1 DBPR/LT 1 regulatory development interval established by Congress is

required to allow for the preliminary planning and design steps which

are inherent in any capital improvement process.

    In the case of ground water systems, the statutory deadline for

promulgation of the GWR is May 2002. However, EPA intends to promulgate

this rule by November 2000, in order to allow three years for

compliance and still ensure simultaneous compliance by ground water

systems with the Stage 1 DBPR and the GWR. As in the case of subpart H

systems serving fewer than 10,000, system operators will not know until

November 2000 what the final compliance requirements for both rules

are. EPA thus believes it appropriate to grant the additional two years

for compliance with the Stage 1 DBPR allowed by the statute.

    EPA has been very successful in meeting all of the new statutory

deadlines and is on track for the LT1 Rule and GWR. While EPA fully

intends to meet the schedule discussed earlier, if those rules are

delayed the Agency will evaluate all available options to protect

against unacceptable risk-risk trade-offs. Part of this effort is the

extensive outreach to systems already underway to fully inform water

supplies of the likely elements in the upcoming rules. In addition, EPA

would consider including provisions for streamlined variance and/or

exemption processing in these rules if they were delayed, in order to

enhance State flexibility in ensuring that compliance with the Stage 1

DBPR is not required before the corresponding microbial protection

rule.

    Under today's Stage 1 DBPR, EPA has already provided small subpart

H systems and ground water systems the two-year extension for capital

improvements since these systems will not know with certainty until

November 2000 if capital improvements will be needed for simultaneous

compliance with the Stage 1 DBPR and LT1/GWR. States considering

whether to grant a two-year capital improvement extension for

compliance with the GWR or LT1 will also need to consider the impact of

such extensions on compliance with today's rule, given that a similar

extension for capital improvement has already been provided in the

initial compliance schedule for the Stage 1 DBPR. EPA believes,

however, that these systems will generally not require extensive

capital improvements that take longer than three years to install to

meet Stage 1 DBPR, GWR, and LT1 requirements, or will require no

capital improvements at all. However if needed, EPA will work with

States and utilities to address systems that require time beyond

November 2003 to comply. This strategy may include exemptions.

    In addition, EPA will provide guidance and technical assistance to

States and systems to facilitate timely compliance with both DBP and

microbial requirements. EPA will request comment on how best to do this

when the Agency proposes the LTESWTR and GWR.

3. Summary of Comments

    Commenters were in general agreement that the compliance deadline

strategy contained in the fourth option of the 1997 NODA did the best

job of complying with the requirements to 1996 SDWA Amendments and

meeting the objectives of the 1993 Reg. Neg. Agreement that Congress

affirmed as part of the 1996 Amendments. Nonetheless, a number of

commenters expressed concern about the ability of large surface water

systems that had to make capital improvements to comply with all

requirements of the Stage 1 DBPR and IESWTR. They pointed out that

capital improvements include more than just the construction, but also

financing, design, and approval.

    EPA believes that the provisions of Section 1412(b)(10) of the SDWA

as amended allow systems the flexibility needed to comply. As noted

earlier in this section, States may grant up to an additional two years

compliance time for an individual system if capital improvements are

necessary. Moreover, as both of these rules have been under negotiation

since 1992, proposed in 1994 and further clarified in 1997, EPA

believes that most systems have had substantial time to consider how to

proceed with implementation and to initiate preliminary planning.

Several commenters also supported delaying the promulgation of the

Stage 1 DBPR for ground water systems until the GWR is promulgated, in

order to ensure simultaneous compliance with both rules. EPA believes

that this option would not be consistent with the reg-neg agreement, as

endorsed by Congress, because the agreement specifies that the Stage 1

DBPR will apply to all community and nontransient noncommunity water

systems. Moreover, EPA has committed to the LT1 and GWR promulgation

schedule outlined above precisely to address this issue.

    In conclusion EPA believes that the compliance deadlines outlined

above for systems covered by this rule are appropriate and consistent

with the requirements of the 1996 SDWA amendments. The Agency notes,

however, that some elements of Option 4 outlined in the 1997 NODA apply

to systems that may be covered by future Long Term Enhanced and Ground

Water rules. EPA intends to follow the deadline strategy outlined in

Option 4 for these future rules. However, as today's action only

relates to the Stage 1 DBPR, the Agency will defer final action on

deadlines associated with future rules until those rules, themselves,

are finalized.



[[Page 69429]]



J. Public Notice Requirements



1. Today's Rule

    Today's action addresses public notification by promulgating public

notification language for the regulated compounds in 40 CFR Section

141.32 (e). EPA takes this opportunity to note that the 1996 amendments

to the SDWA require the Agency to make certain changes to the public

notice regulations. EPA intends to propose changes to the public notice

requirements in the Federal Register shortly after promulgation of the

Stage 1 DBPR. Applicable changes in the public notice requirements,

when they become effective, will supersede today's provisions. In

general, the public notification for the Stage 1 DBPR is not

substantially changed from that included in the 1994 Proposed Stage 1

DBPR (EPA, 1994a).

2. Background and Analysis

    Under Section 1414(c)(1) of the Act, each owner or operator of a

public water system must give notice to the persons served by the

system of (1) any violation of any MCL, treatment technique

requirement, or testing provision prescribed by an NPDWR; (2) failure

to comply with any monitoring requirement under section 1445(a) of the

Act; (3) existence of a variance or exemption; (4) failure to comply

with the requirements of a schedule prescribed pursuant to a variance

or exemption; and (5) notice of the concentration level of any

unregulated contaminant for which the Administrator has required public

notice.

    EPA promulgated the current regulations for public notification on

October 28, 1987 (52 FR 41534--EPA, 1987). These regulations specify

general notification requirements, including frequency, manner, and

content of notices, and require the inclusion of EPA-specified health

effects information in each public notice. The public notification

requirements divide violations into two categories (Tier 1 and Tier 2)

based on the seriousness of the violations, with each tier having

different public notification requirements. Tier 1 violations include

violations of an MCL, treatment technique, or a variance or exemption

schedule. Tier 1 violations contain health effects language specified

by EPA which concisely and in non-technical terms conveys to the public

the adverse health effects that may occur as a result of the violation.

States and water utilities remain free to add additional information to

each notice, as deemed appropriate for specific situations. Tier 2

violations include monitoring violations, failure to comply with an

analytical requirement specified by an NPDWR, and operating under a

variance or exemption.

    Today's final rule contains specific health effects language for

the contaminants which are in today's rulemaking. EPA believes that the

mandatory health effects language is the most appropriate way to inform

the affected public of the potential health implications of violating a

particular EPA standard.

3. Summary of Comments

    EPA received comments on the topic of the public notification

language for TTHM, HAA5, chlorine, chloramines, chlorine dioxide, and

enhanced coagulation. Some commenters noted that the language in

141.32(e)(79) is satisfactory. One commenter requested that the

language for DBPs be modified to recognize that disinfectants react

with naturally occurring organic and inorganic matter to form DBPs.

Some commenters did not support the use of the same public notification

language for both DBP MCL and enhanced coagulation treatment technique

violations. Several commenters suggested that the content of the

notices for chlorine, chloramine, and chlorine dioxide should reflect

that disinfection is an essential step in surface water treatment. One

commenter suggested that the language for chlorine dioxide acute

effects should be deleted. Other commenters felt that the notice to

consumers of chlorine dioxide violations at the treatment facility

which do not result in violations in the distribution system (nonacute

violations) should not require public notification.

    In response, EPA has modified the public notification language for

DBPs to indicate that disinfectants react with naturally occurring

organic and inorganic matter to form DBPs. EPA believes it is

appropriate to use the same public notification language for the

enhanced coagulation treatment technique violation as for violations

for the TTHM and HAA5 MCLs, since enhanced coagulation is meant to

limit exposure to DBPs. EPA believes the current language in the public

notification language is appropriate to reflect that disinfection is an

essential step in water treatment. EPA believes that since the

potential health effects from chlorine dioxide are short-term that it

is appropriate to maintain the acute effects language to protect the

fetus, infants, and children. In general, the public notification

requirements for the Stage 1 DBPR will not substantially change from

that included in the 1994 Proposed Stage 1 DBPR (EPA, 1994a).



K. System Reporting and Record Keeping Requirements



1. Today's Rule

    The Stage 1 DBPR, consistent with the current system reporting

regulations under 40 CFR 141.31, requires PWSs to report monitoring

data to States within ten days after the end of the compliance period.

In addition, systems are required to submit the data required in

Sec. 141.134. These data are required to be submitted quarterly for any

monitoring conducted quarterly or more frequently, and within 10 days

of the end of the monitoring period for less frequent monitoring.

Systems that are required to do extra monitoring because of the

disinfectant used have additional reporting requirements specified.

This applies to systems that use chlorine dioxide (must report chlorine

dioxide and chlorite results) and ozone (must report bromate results).

    Subpart H systems that use conventional treatment are required to

report either compliance/noncompliance with DBP precursor (TOC) removal

requirements or report which of the enhanced coagulation/enhanced

softening exemptions they are meeting. There are additional

requirements for systems that cannot meet the required TOC removals and

must apply for an alternate enhanced coagulant level. These

requirements are included in Sec. 141.134(b).

    Calculation of compliance with the TOC removal requirements is

based on normalizing the percent removals over the most recent four

quarters, since compliance is based on that period. Normalization,

which would prescribe equal weight to the data collected each month, is

necessary since source water quality changes may change the percent TOC

removal requirements from one month to another. EPA has developed a

sample reporting and compliance calculation sheet that will be

available in the enhanced coagulation guidance manual to assist

utilities in making these calculations.

2. Summary of Comments

    There were no significant comments on the system reporting and

recordkeeping requirements and therefore EPA is finalizing the

requirements as proposed.



L. State Recordkeeping, Primacy, and Reporting Requirements



    The SDWA provides that States and eligible Indian Tribes may assume

primary enforcement responsibilities.



[[Page 69430]]



Fifty-four out of fifty-six State and territorial jurisdictions have

applied for and received primary enforcement responsibility (primacy)

under the Act. No Tribes have received primacy. To obtain primacy for

the federal drinking water regulations, States must adopt their own

regulations which are at least as stringent as the federal regulations.

This section describes the regulations and other procedures and

policies that States must adopt to implement the final Stage 1 DBPR.

    To implement the final rule, States are required to adopt the

following regulatory requirements:



--Section 141.32, Public Notification;

--Section 141.64, MCLs for Disinfection Byproducts;

--Section 141.65, MRDLs for Disinfectants;

--Subpart L, Disinfectant Residuals, Disinfectant Byproducts, and

Disinfection Byproduct Precursors.



    In addition to adopting regulations no less stringent than the

federal regulations, States must adopt certain requirements related to

this regulation in order to have their program revision applications

approved by EPA. This rule also requires States to keep specific

records and submit specific reports to EPA.

    On April 28, 1998, EPA amended its State primacy regulations at 40

CFR 142.12 to incorporate the new process identified in the 1996 SDWA

amendments for granting primary enforcement authority to States while

their applications to modify their primacy programs are under review

(63 FR 23362; EPA, 1998i). The new process grants interim primary

enforcement authority for a new or revised regulation during the period

in which EPA is making a determination with regard to primacy for that

new or revised regulation. This interim enforcement authority begins on

the date of the primacy application submission or the effective date of

the new or revised State regulation, whichever is later, and ends when

EPA makes a final determination. However, this interim primacy

authority is only available to a State that has primacy for every

existing national primary drinking water regulation in effect when the

new regulation is promulgated.

    As a result, States that have primacy for every existing NPDWR

already in effect may obtain interim primacy for this rule, beginning

on the date that the State submits its complete and final primacy

application for this rule to EPA, or the effective date of its revised

regulations, whichever is later. In addition, a State which wishes to

obtain interim primacy for future NPDWRs must obtain primacy for this

rule.

1. State Recordkeeping Requirements

    a. Today's Rule. The current regulations in Sec. 142.14 require

States with primacy to keep various records, including analytical

results to determine compliance with MCLs, MRDLs, and treatment

technique requirements; system inventories; State approvals;

enforcement actions; and the issuance of variances and exemptions. The

Stage 1 DBPR requires States to keep additional records of the

following, including all supporting information and an explanation of

the technical basis for each decision:

    (1) Records of determinations made by the State when the State has

allowed systems additional time to install GAC or membrane filtration.

These records must include the date by which the system is required to

have completed installation;

    (2) Records of systems that are required to meet alternative

minimum TOC removal requirements or for whom the State has determined

that the source water is not amendable to enhanced coagulation. These

records must include the results of testing to determine alternative

limits and the rationale for establishing the alternative limits;

    (3) Records of subpart H systems using conventional treatment

meeting any of the enhanced coagulation or enhanced softening exemption

criteria;

    (4) Register of qualified operators;

    (5) Records of systems with multiple wells considered to be one

treatment plant for purposes of determining monitoring frequency;

    (6) Records of the sampling plans for subpart H systems serving

more than 3,300 persons must be keep on file at the State after

submission by the system;

    (7) A list of laboratories that have completed performance sample

analyses and achieved the quantitative results for TOC, TTHMs, HAA5,

bromate, and chlorite; and

    (8) A list of all systems required to monitor for disinfectants and

DBPs under subpart L.

    b. Background and Analysis. In addition to requesting comments on

the requirements (1) through (5), and (7) and (8) listed above, EPA

also requested comments on whether States should be required to keep

the monitoring plan submitted by systems serving more than 3,300 people

on file at the State after submission to make it available for public

review.

    c. Summary of Comments. There were several commenters who suggested

that EPA should keep in mind State budget constraints when requiring

specific additional recordkeeping requirements. Other commenters stated

that they believed the requirements were necessary. EPA understands

commenters concerns with requiring recordkeeping requirements that are

unnecessary, but believes this information is important to conduct

effective State program oversight, including the review of State

decisions and their basis. After further review, EPA has decided to

eliminate the requirement in the proposal that States must keep records

of systems that apply for alternative TOC performance criteria. EPA is

more concerned with the systems that are required to meet alternative

TOC performance criteria, not the systems that have applied for the

alternative performance criteria. In addition, EPA has added three

recordkeeping requirements, two of which were originally in the

reporting requirements section and one for which EPA requested comment.

    The first additional requirement will require States to keep lists

of all systems required to monitor for various disinfectants and DBPs

(#8 above). The second additional requirement will require States to

maintain a list of laboratories that have completed performance sample

analyses and achieved the quantitative results for TOC, TTHMs, HAA5,

bromate, and chlorite (#6 above). EPA believes both of these

recordkeeping requirements are necessary to ensure adequate EPA program

oversight. As discussed below, these two requirements are no longer in

the State reporting requirements as EPA has decided that the

requirements in the proposal on State reporting requirements are not

needed on a regular basis, but are needed for program oversight. The

third additional requirement pertains to the request for comment in the

proposal on maintaining the monitoring plans submitted by systems (#6

above). Several commenters supported this additional requirement

stating that it was a necessary element for implementing the final

rule. Others believed it was not necessary to keep this on file because

the public could request this information from the system or the State

as normal public records. EPA believes that it is important for States

to review, and keep on file the systems monitoring plan to ensure that

the PWS is monitoring and calculating compliance in accordance with the

plan. This will also enable the public to view the plan. Thus, EPA is

adding this requirement to the final recordkeeping requirements. In

conclusion, based on a review of all public comments the final



[[Page 69431]]



rule contains eight State recordkeeping requirements in addition to

those required under current regulations in Sec. 142.14.

2. Special Primacy Requirements

    a. Today's Rule. To ensure that a State program includes all the

elements necessary for an effective and enforceable program under

today's rule, a State application for program revision approval must

include a description of how the State will:

    (1) Determine the interim treatment requirements for systems

granted additional time to install GAC and membrane filtration under

141.64(b)(2).

    (2) Qualify operators of community and nontransient noncommunity

water systems subject to this regulation under 141.130(c).

Qualification requirements established for operators of systems subject

to 40 CFR Part 141 Subpart H (Filtration and Disinfection) may be used

in whole or in part to establish operator qualification requirements

for meeting subpart L requirements if the State determines that the

subpart H requirements are appropriate and applicable for meeting

subpart L requirements.

    (3) Approve DPD colorimetric tests kits for free and total chlorine

measurements under 141.131(c)(2). State approval granted under subpart

H (Sec. 141.74(a)(2)) for the use of DPD colorimetric test kits for

free chlorine testing would be considered acceptable approval for the

use of DPD test kits in measuring free chlorine residuals as required

in subpart L.

    (4) Approve parties to conduct analyses of water quality parameters

under 141.132(a)(2) (pH, alkalinity, bromide, and residual disinfectant

concentration measurements). The State's process for approving parties

performing water quality measurements for systems subject to subpart H

requirements may be used for approving parties measuring water quality

parameters for systems subject to subpart L requirements, if the State

determines the process is appropriate and applicable.

    (5) Define criteria to use in determining if multiple wells are

being drawn from a single aquifer and therefore can be considered as a

single source under 141.132(a)(2). Such criteria will be used in

determining the monitoring frequency for systems using only ground

water not under the direct influence of surface water.

    (6) Approve alternative TOC removal levels as allowed under

141.135(b).

    b. Background and Analysis. As discussed above, EPA included

several special primacy requirements to ensure that State programs

contain all the essential elements for an effective program.

Specifically, EPA believes the special requirements are important to

ensure that the process or approach used by the State for evaluating

whether the interim treatment in place for systems granted additional

time to install GAC or membranes or alternative enhanced coagulation

levels will be protective of public health. The requirement to have

qualified operators is important because the treatment technologies

used to comply with the Stage 1 DBPR and the IESWTR simultaneously are

complex and will require a certain level of expertise. The requirement

to approve parties for conducting analyses of specific water quality

parameters is important because each of the parameters required to be

tested is critical to a specific component of the final rule (e.g.,

bromide ion is important because for bromate it is possible to reduce

monitoring from monthly to once per quarter, if a system demonstrates

that the average raw water bromide concentration is less than 0.05 mg/L

based upon representative monthly measurements for one year). Finally,

it is important to define the criteria used to determine if multiple

wells are to be considered a single source as this could have

significant implications for monitoring.

    c. Summary of Comments. There were no significant comments on the

primacy requirements. The only change from the proposal was to delete

the requirement that States must have approved parties to perform

temperature evaluations. This requirement was included in the proposed

rule because of the need to have accurate measurements as a part of the

process for not allowing predisinfection credit. Since the final rule

allows credit for compliance with applicable disinfection requirements

consistent with the SWTR, the temperature requirement was removed.

3. State Reporting Requirements

    a. Today's Rule. EPA currently requires in Sec. 142.15 that States

report to EPA information such as violations, variance and exemption

status, and enforcement actions. The Stage 1 DBPR does not add any

additional reporting requirements.

    b. Background and Analysis. The preamble to the proposed rule

included six State reporting requirements. These included:

    (1) A list of all systems required to monitor for various

disinfectants and disinfection byproducts;

    (2) A list of all systems for which the State has granted

additional time for installing GAC or membrane technology and the basis

for the additional time;

    (3) A list of laboratories that have completed performance sample

analyses and achieved the quantitative results for TOC, TTHMs, HAA5,

bromate, and chlorite;

    (4) A list of all systems using multiple ground water wells which

draw from the same aquifer and are considered a single source for

monitoring purposes;

    (5) A list of all Subpart H systems using conventional treatment

which are not required to operate with enhanced coagulation, and the

reason why enhanced coagulation is not required for each system; and

    (6) A list of all systems with State-approved alternate performance

standards (alternate enhanced coagulation levels).

    c. Summary of Comments. Several commenters stated that the

reporting requirements were not necessary to operate an oversight

program and that these reports could be made available for EPA review

during annual audits. EPA agrees with commenters that the reports are

not necessary to operate an oversight program, and that if needed EPA

could request this information from the States. However, EPA does

believe it is important that States maintain this information in their

records. In conclusion, based on commenters concerns and for the

reasons cited above, the final rule contains no additional State

reporting requirements other than those required by 142.15.

 

M. Variances and Exemptions



1. Today's Rule

    Variances may be granted in accordance with section 1415(a)(1)(A)

of the SDWA and in accordance with 1415(e) and EPA's regulations.

Exemptions may be granted in accordance with section 1416(a) of the

SDWA and EPA's regulations.

2. Background and Analysis

    Variances. The SDWA provides for two types of variances--general

variances and small system variances. Under section 1415(a)(1)(A) of

the SDWA, a State which has primary enforcement responsibility

(primacy), or EPA as the primacy agency, may grant variances from MCLs

to those public water systems of any size that cannot comply with the

MCLs because of characteristics of the water sources. The primacy

agency may grant general variances to a system on condition that the

system install the best available technology, treatment techniques, or

other means, and provided that alternative sources of water are not



[[Page 69432]]



reasonably available to the system. At the time this type of variance

is granted, the State must prescribe a compliance schedule and may

require the system to implement additional control measures.

Furthermore, before EPA or the State may grant a general variance, it

must find that the variance will not result in an unreasonable risk to

health (URTH) to the public served by the public water system.

    Under section 1413(a)(4), States that choose to issue general

variances must do so under conditions, and in a manner, that are no

less stringent than section 1415. Of course, a State may adopt

standards that are more stringent than the EPA standards. EPA specifies

BATs for general variance purposes. EPA may identify as BAT different

treatments under section 1415 for variances other than the BAT under

section 1412 for MCLs. EPA's section 1415 BAT findings may vary

depending on a number of factors, including the number of persons

served by the public water system, physical conditions related to

engineering feasibility, and the costs of compliance with MCLs. In this

final rule, EPA is not specifying different BAT for variances under

section 1415(a). Section 1415(e) authorizes the primacy Agency (EPA or

the State) to issue variances to small public water systems (those

serving less than 10,000 persons) where the system cannot afford to

comply with an MCL and where the primacy agency determines that the

terms of the variances ensure adequate protection of public health (63

FR 1943-57; EPA, 1998j). These variances also may only be granted where

EPA has identified a variance technology under Section 1412(b)(15) for

the contaminant, system size and source water quality in question.

    Prior to the 1996 SDWA amendments, EPA was required to set the MCL

for a contaminant as close to the MCLG as is feasible. Section

1412(b)(4)(D) of the SDWA states that ``the term ``feasible'' means

with the use of the best technology, treatment techniques and other

means which the Administrator finds, after examination for efficacy

under field conditions and not solely under laboratory conditions, are

available (taking cost into consideration).''

    The cost assessment for the feasibility determinations have

historically been based upon impacts to regional and large metropolitan

water systems serving populations greater than 50,000 people. Since

large systems served as the basis for the feasibility determinations,

the technical and/or cost considerations associated with these

technologies often were not applicable to small water systems. While

EPA will continue to use feasibility for large systems in setting

NPDWRs, the 1996 amendments to the SDWA specifically require EPA to

make small system technology assessments for both existing and future

regulations.

    The 1996 amendments to the SDWA identifies three categories of

small public water systems that need to be addressed: (1) those serving

a population between 3301 to 10,000; (2) those serving a population of

501--3300; and (3) those serving a population of 26--500. The SDWA

requires EPA to make determinations of available compliance

technologies and, if needed, variance technologies for each size

category. A compliance technology is a technology that is affordable

and that achieves compliance with the MCL and/or treatment technique.

Compliance technologies can include point-of-entry or point-of-use

treatment units. Variance technologies are only specified for those

system size/source water quality combinations for which there are no

listed compliance technologies.

    EPA has completed an analysis of the affordability of DBP control

technologies for each of the three size categories included above.

Based on this analysis, multiple affordable compliance technologies

were found for each of the three system sizes (EPA, 1998q and EPA,

1998r) and therefore variance technologies were not identified for any

of the three size categories. The analysis was consistent with the

methodology used in the document ``National-Level Affordability

Criteria Under the 1996 Amendments to the Safe Drinking Water Act''

(EPA, 1998s) and the ``Variance Technology Findings for Contaminants

Regulated Before 1996'' (EPA, 1998t).

    Exemptions. Under section 1416(a), EPA or a State may exempt a

public water system from any requirements related to an MCL or

treatment technique of an NPDWR, if it finds that (1) due to compelling

factors (which may include economic factors such as qualification of

the PWS as serving a disadvantaged community), the PWS is unable to

comply with the requirement or implement measure to develop an

alternative source of water supply; (2) the exemption will not result

in an unreasonable risk to health; and; (3) the PWS was in operation on

the effective date of the NPWDR, or for a system that was not in

operation by that date, only if no reasonable alternative source of

drinking water is available to the new system; and (4) management or

restructuring changes (or both) cannot reasonably result in compliance

with the Act or improve the quality of drinking water.

    If EPA or the State grants an exemption to a public water system,

it must at the same time prescribe a schedule for compliance (including

increments of progress or measures to develop an alternative source of

water supply) and implementation of appropriate control measures that

the State requires the system to meet while the exemption is in effect.

Under section 1416(b)(2)(A), the schedule prescribed shall require

compliance as expeditiously as practicable (to be determined by the

State), but no later than 3 years after the effective date for the

regulations established pursuant to section 1412(b)(10). For public

water systems which do not serve more than a population of 3,300 and

which need financial assistance for the necessary improvements, EPA or

the State may renew an exemption for one or more additional two-year

periods, but not to exceed a total of 6 years, if the system

establishes that it is taking all practicable steps to meet the

requirements above.

    A public water system shall not be granted an exemption unless it

can establish that either: (1) the system cannot meet the standard

without capital improvements that cannot be completed prior to the date

established pursuant to section 1412(b)(10); (2) in the case of a

system that needs financial assistance for the necessary

implementation, the system has entered into an agreement to obtain

financial assistance pursuant to section 1452 or any other Federal or

state program; or (3) the system has entered into an enforceable

agreement to become part of a regional public water system.

3. Summary of Comments on Variance and Exemptions

    In the 1994 proposal, EPA requested comment on whether exemptions

to the rule should be granted if a system could demonstrate to the

State that due to unique water quality characteristics it could not

avoid, through the use of BAT, the possibility of increasing total

health risk to its consumers by complying with the Stage 1 regulations.

The Agency requested information under which such a scenario may

unfold. Several commenters supported granting exemptions provided a

system could demonstrate that installation of BAT will increase the

total health risk.

    After additional consideration, EPA believes it is not appropriate,

for several reasons, to grant exemptions based on a demonstration that

the use of BAT could increase the total health risk by complying with

the Stage 1 DBPR. First,



[[Page 69433]]



EPA does not believe the analytical tools and methodologies are

currently available that would allow a determination of whether the

total health risk from the installation of BAT would increase. Second,

at the time of proposal there was concern that in waters with high

bromide concentrations it may be possible to increase the

concentrations of certain brominated DBPs when using precursor removal

processes even though the concentrations of the TTHMs and HAA5 may

decrease. Also, at the time of proposal, the health risks associated

with many of the brominated DBPs was unknown, and it was unclear

whether the benefits of lowering the concentrations of chlorinated DBPs

outweigh the possible downside risks of increasing certain brominated

DBPs. Since the proposal, some additional health effects research has

been completed evaluating the toxicity of brominated DBPs. However,

this research is still preliminary and no conclusions can be drawn on

the potential for increased risks from the brominated DBPs. In

addition, it is unclear to what extent the use of precursor removal

processes will change the concentrations of certain brominated DBPs.

The ICR data should provide some additional information that may be

helpful in this area along with additional ongoing research. This

information will be available for consideration in the Stage 2 rule

deliberations. Based on the reasons stated above, EPA does not believe

it is appropriate to allow exemptions to the rule based on a finding

that the installation of BAT would increase the total risk from DBPs.



N. Laboratory Certification and Approval



1. Today's Rule

    EPA recognizes that the effectiveness of today's regulations

depends on the ability of laboratories to reliably analyze the

regulated disinfectants and DBPs at the MRDL or MCL, respectively.

Laboratories must also be able to measure the trihalomethanes and

haloacetic acids at the reduced monitoring trigger levels, which are

between 25 and 50 percent of the MCLs for these compound classes. EPA

has established State primacy requirements for a drinking water

laboratory certification program for the analysis of DBPs. States must

adopt a laboratory certification program as part of primacy. [40 CFR

142.10(b)]. EPA has also specified laboratory requirements for analyses

of DBP precursors and disinfectant residuals which must be conducted by

approved parties. [40 CFR 141.89 and 141.74]. EPA's ``Manual for the

Certification of Laboratories Analyzing Drinking Water'', EPA 815-B-97-

001--(EPA, 1997g), specifies the criteria for implementation of the

drinking water laboratory certification program.

    In today's rule, EPA is promulgating MCLs for TTHMs, HAA5, bromate,

and chlorite. Today's rule requires that only certified laboratories be

allowed to analyze samples for compliance with the proposed MCLs. For

the disinfectants and certain other parameters in today's rule, which

have MRDLs or monitoring requirements, EPA is requiring that analyses

be conducted by a party acceptable to the State.

    Performance evaluation (PE) samples, which are an important tool in

the SDWA laboratory certification program (laboratories seeking

certification) may be obtained from a PE provider approved by the

National Institute of Science and Technology (NIST). To receive and

maintain certification, a laboratory must use a promulgated method and,

at least once per year, successfully analyze an appropriate PE sample.

In the drinking water PE studies, NIST-approved providers will provide

samples for bromate, chlorite, five haloacetic acids, four

trihalomethanes, free chlorine, and alkalinity. The NIST-approved PE

providers will provide total chlorine and TOC samples in the wastewater

PE studies and have the potential to provide these samples for drinking

water studies. Due to the lability of chlorine dioxide, EPA does not

expect a suitable PE sample can be designed for chlorine dioxide

measurements.

    PE Sample Acceptance Limits for Laboratory Certification.

Historically, EPA has set minimum PE acceptance limits based on one of

two criteria: statistically derived estimates or fixed acceptance

limits. Statistical estimates are based on laboratory performance in

the PE study. Fixed acceptance limits are ranges around the true

concentration of the analyte in the PE sample. Today's rule combines

the advantages of these approaches by specifying statistically-derived

acceptance limits around the study mean, within specified minimum and

maximum fixed criteria.

    EPA believes that specifying statistically-derived PE acceptance

limits with upper and lower bounds on acceptable performance provides

the flexibility necessary to reflect improvement in laboratory

performance and analytical technologies. The acceptance criteria

maintain minimum data quality standards (the upper bound) without

artificially imposing unnecessarily strict criteria (the lower bound).

Therefore, EPA is establishing the following acceptance limits for

measurement of bromate, chlorite, each haloacetic acid, and each

trihalomethane in a PE sample.

    EPA is defining acceptable performance for each chemical measured

in a PE sample from estimates derived at a 95% confidence interval from

the data generated by a statistically significant number of

laboratories participating in the PE study. However, EPA requires that

these acceptance criteria not exceed <plus-minus>50% nor be less than

<plus-minus>15% of the study mean. If insufficient PE study data are

available to derive the estimates required for any of these compounds,

the acceptance limit for that compound will be set at <plus-minus>50%

of the study true value. The true value is the concentration of the

chemical that EPA has determined was in the PE sample.

    EPA recognizes that when using multianalyte methods, the data

generated by laboratories that are performing well will occasionally

exceed the acceptance limits. Therefore, to be certified to perform

compliance monitoring using a multianalyte method, laboratories are

required to generate acceptable data for at least 80% of the regulated

chemicals in the PE sample that are analyzed with the method. If fewer

than five compounds are included in the PE sample, data for each of the

analytes in that sample must meet the minimum acceptance criteria in

order for the laboratory to be certified.

    Approval Criteria for Disinfectants and Other Parameters. Today's

rule establishes MRDLs for the three disinfectants--chlorine,

chloramines, and chlorine dioxide. In addition, EPA has established

monitoring requirements for TOC, alkalinity, and bromide; there are no

MCLs for these parameters. In previous rules [40 CFR 141.28, .74, and

.89], EPA has required that measurements of alkalinity, disinfectant

residuals, pH, temperature, and turbidity be made with an approved

method and conducted by a party approved (not certified) by the State.

In today's rule, EPA requires that samples collected for compliance

with today's requirements for alkalinity, bromide, residual

disinfectant, and TOC be conducted with approved methods and by a party

approved by the State.

    Other Laboratory Performance Criteria. For all contaminants and

parameters required to be monitored in today's rule, the States may

impose other requirements for a laboratory to be



[[Page 69434]]



certified or a party to be approved to conduct compliance analyses.

2. Background and Analysis

    The laboratory certification and approval requirements that today's

rule establishes are unchanged from those proposed by EPA in 1994.

3. Summary of Comments

    EPA received few comments on laboratory certification and approval.

Commenters requested clarification of the use of the <plus-minus>50%

upper bound and <plus-minus>15% lower bound, along with the use of

statistically derived limits. EPA believes that statistically derived

limits provide flexibility to allow laboratory certification standards

to reflect improvement in laboratory performance and analytical

technologies. As laboratories become more proficient in conducting

these analyses, statistically derived acceptance limits may drop.

However, to prevent the exclusion of laboratories capable of producing

data of sufficient quality for compliance purposes, EPA has established

a lower bound for acceptance limits of <plus-minus>15%. EPA is imposing

an upper bound on acceptable performance to establish minimum data

quality standards. Results outside of this range have unacceptable

accuracy for compliance determinations. These upper and lower bounds

were not determined statistically; they are the data quality objectives

the Agency has determined as acceptable.



IV. Economic Analysis



    Under Executive Order 12866, Regulatory Planning and Review, EPA

must estimate the costs and benefits of the Stage 1 DBPR in a

Regulatory Impact Analysis (RIA) and submit the analysis to Office of

Management and Budget (OMB) in conjunction with publishing the final

rule. EPA has prepared an RIA to comply with the requirements of this

Order. This section provides a summary of the information from the RIA

for the Stage 1 DBPR (USEPA 1998g).



A. Today's Rule



    EPA has estimated that the total annualized cost, for implementing

the Stage 1 DBPR is $701 million in 1998 dollars (assuming a 7 percent

cost of capital). This estimate includes annualized treatment costs to

utilities ($593 million), start-up and annualized monitoring costs to

utilities ($91.7 million), and startup and annualized monitoring costs

to states ($17.3 million). Annualized treatment costs to utilities

includes annual operation and maintenance costs ($362 million) and

annualized capital costs assuming 7 percent cost of capital ($230

million). The basis for these estimates, and alternate cost estimates

using different cost of capital assumptions are described later in this

section. While the benefits of this rule are difficult to quantify

because of the uncertainty associated with risks from exposure to DBPs

(and the resultant reductions in risk due to the decreased exposure

from DBPs), EPA believes that there is a reasonable likelihood that the

benefits will exceed the costs. Various approaches for assessing the

benefits are considered and described in the benefits and net benefits

sections of this preamble.



B. Background



1. Overview of RIA for the Proposed Rule

    In the RIA for the 1994 proposed Stage 1 DBPR (EPA, 1994i) EPA

estimated the national capital and annualized utility costs (sum of

amortized capital and annual operating costs, assuming 10% cost of

capital) for all systems at $4.4 billion and $1.04 billion,

respectively. The cost and reduction in DBP exposure estimates of the

1994 RIA were derived using a Disinfection Byproduct Regulatory

Analysis Model (DBPRAM). The DBPRAM consisted of a collection of

analytical models which used Monte Carlo simulation techniques to

produce national forecasts of compliance and exposure reductions for

different regulatory scenarios. The TWG, representing members of the

Reg. Neg. Committee, used the best available information at the time as

inputs to the DBPRAM, and for making further adjustments to the model

predictions. The Stage 1 DBPR compliance and exposure forecasts were

affected by constraints imposed by the 1994 proposed IESWTR option

which would have required systems to provide enough disinfection, while

not allowing for disinfection credit prior to TOC removal by enhanced

coagulation, to achieve a 10<INF>-4</INF> annual risk of infection from

Giardia (EPA, 1994a). The compliance forecast assumed that a

substantial number of systems would need to install advanced

technologies to meet the Stage 1 DBPR because of needing to achieve the

10<INF>-4</INF> annual risk level from Giardia while no longer being

allowed disinfection credit prior to TOC removal.

    Predicted benefits for the proposed Stage 1 DBPR were derived

assuming a baseline risk ranging from 1 to 10,000 cancer cases per year

(based on analysis of available toxicological and epidemiological data)

and assuming reductions in the cancer risks were proportional to

reductions in TTHM, HAA5, or TOC levels (predicted from compliance

forecasts). Negotiators agreed that the range of possible risks

attributed to chlorinated water should consider both toxicological data

and epidemiological data, including the Morris et al. (1992) estimates.

No consensus, however, could be reached on a single likely risk

estimate. Therefore, the predicted benefits for the proposal ranged

from one to several thousands cases of cancer being avoided per year

after implementation of the Stage 1 DBPR. Despite, the uncertainty in

quantifying the benefits from the Stage 1 DBPR, the Reg. Neg. Committee

recognized that risks from chlorinated water could be large, and

therefore should be reduced. The Reg. Neg. Committee also recommended

that the proposed Stage 1 DBPR provided the best means for reducing

risks from DBPs until better information become available.

    For a more detailed discussion of the cost and benefit analysis of

the 1994 proposed DBPR refer to the preamble of the proposed rule (EPA,

1994a) and the RIA for the proposed rule (EPA, 1994i).

2. Factors Affecting Changes to the 1994 RIA

    a. Changes in Rule Criteria. Based on the new data reflecting the

feasibility of enhanced coagulation, as discussed previously, the

enhanced coagulation requirements were modified by decreasing the

percent TOC removal requirements by 5 percent for systems with low TOC

level waters (i.e., 2-4 mg/L TOC). These new percent TOC removal

requirements were used with new source and finished water TOC

occurrence data to revise the estimates for the number of systems

requiring enhanced coagulation.

    The IESWTR was revised from the proposal to allow inactivation

credit for disinfection prior to and during stages of treatment for

precursor removal. Also, the proposed IESWTR was revised to include

disinfection benchmark criteria, in lieu of requiring treatment to an

acceptable risk level, to prevent increases in microbial risk while

systems complied with the Stage 1 DBPR. These two rule changes were

considered in revising the forecasts of compliance and changes in

exposure resulting from the Stage 1 DBPR.

    b. New Information Affecting DBP Occurrence and Compliance

Forecasts. Since the rule was proposed, new sources of data have become

available that were used to update the 1994 RIA. The new data includes:



[[Page 69435]]



    <bullet> Updated costs for different treatment technologies (e.g.,

membranes) used in the DBP Cost and Technology Document, (EPA, 1998k);

    <bullet> 1996 data from the AWWA Water Industry Data Base on TOC,

TTHM and HAA5 occurrence, and disinfection practices;

    <bullet> Plant schematics of treatment processes for ICR utilities;

    <bullet> Research data from numerous sources regarding the efficacy

of enhanced coagulation for precursor removal and resultant DBP

formation (Krasner, 1997; and EPA, 1997b);

    <bullet> New research results produced in jar tests by TWG members

documenting the effect of moving the point of predisinfection under

varying conditions (Krasner, 1997 and EPA, 1997b).

    This new information has been described in the 1997 DBP NODA (EPA,

1997b). Public comments received in 1997, supported using the above

information in revising the decision tree analysis. Discussion on the

decision tree changes are in section IV.C of this preamble.

    c. New Epidemiology Information. Since the proposal, EPA has

completed an reassessment of the Morris et al. (1992) meta-analysis

(Poole, 1997). Review of the meta-analysis indicated that the estimate

of cancer cases had limited utility for risk assessment purposes for

methodological reasons (EPA, 1998l and EPA, 1998m). EPA has decided not

to use the Morris et al. (1992) meta-analysis to estimate the potential

benefits from the Stage 1 DBPR. EPA has considered new epidemiology

studies conducted since the time of proposal and completed an

assessment of the potential number of bladder cancer cases that could

be attributed to exposure from chlorinated surface waters. Based on

this assessment of epidemiological studies, EPA estimates that between

1100-9300 bladder cancer cases per year could be attributed to exposure

to chlorinated surface waters (EPA, 1998c). Due to the wide uncertainty

in these estimates, the true number of attributable cases could also be

zero. The basis for these bladder cancer case estimates and potential

reductions in risk resulting from the Stage 1 DBPR is discussed further

in the benefits and net benefits sections that follow.



C. Cost Analysis



    National cost estimates of compliance with the Stage 1 DBPR were

derived from estimates of utility treatment costs, monitoring and

reporting costs, and start-up costs. Utility treatment costs were

derived using compliance forecasts of technologies to be used and unit

costs for the different technologies.

1. Revised Compliance Forecast

    The TWG, supporting the M-DBP Advisory Committee, used the 1996

AWWA Water Industry Data Base (WIDB) to reevaluate the compliance

decision tree used in the RIA for the 1994 proposal. The WIDB provided

occurrence data on TOC level in raw water and finished water, TTHM and

HAA5 levels within distribution systems, and information on

predisinfection practices.

    The above information was used to predict treatment compliance

choices that plants would likely make under the Stage 1 DBPR. Table IV-

1 illustrates how the compliance forecast changed for large systems

using surface water since the time of proposal.



Table IV-1.--Comparisons of Compliance Forecasts for Surface Water Systems Serving <gr-thn-eq>10,000 Population

                                      From the 1994 Proposal and Final Rule

----------------------------------------------------------------------------------------------------------------

                                                                       1994                       1998

                         Treatment                         -----------------------------------------------------

                                                             <SUP># systems     % systems    <SUP># systems     % systems

----------------------------------------------------------------------------------------------------------------

(A) No Further Treatment..................................          386          27.7          544          39.0

(B) Chlorine/Chloramines..................................           41           2.9          231          16.6

(C) Enhanced Coagulation + Chloramines....................          136           9.7          265          19.0

(D) Enhanced Coagulation + Chlorine.......................          600          43.0          265          19.0

(E) Ozone, Chlorine Dioxide, Granular Activated Carbon,

Membranes................................................          232          16.6           90           6.5

                                                           -----------------------------------------------------

    Total *...............................................        1,395         100          1,395         100

----------------------------------------------------------------------------------------------------------------

* May not add to total due to independent rounding.



Notable is that the percentage of systems predicted to use advanced

technologies (ozone, chlorine dioxide, GAC, or membrane) dropped from

17 percent to 6.5 percent since proposal, and the percentage of systems

not affected by the rule increased from 28 percent to 39 percent. This

shift in predicted compliance choices is mainly attributed to less

stringent disinfection requirements under the IESWTR which would reduce

the formation of DBPs and reduce the number of systems requiring

treatment to meet the Stage 1 DBPR. It also appears that a substantial

number of systems may have already made treatment changes to comply

with the 1994 proposed rule.

    Table IV-2 illustrates how the compliance forecast changed for

small systems using surface water since the time of proposal. As for

large systems, the percentage of systems predicted to use advanced

technologies dropped substantially, from 17 percent to 6.5 percent.

This drop in use of advanced technology (i.e., ozone/chloramines and

membrane technologies) is attributed to the change in the IESWTR (as

described above) from the time of proposal. However, unlike for large

systems, the overall percentage of systems predicted to require

treatment modifications did not change. A higher percentage of small

systems (70 percent) are predicted to be affected than large systems

(61 percent) because previously smaller systems did not have to comply

with a TTHM standard.



[[Page 69436]]







  Table IV-2.--Comparison of Compliance Decision Tree for Surface Water Systems Serving <10,000 Population From

                                        the 1994 Proposal and Final Rule

----------------------------------------------------------------------------------------------------------------

                                                                       1994                       1998

                                                           -----------------------------------------------------

                                                             <SUP># systems     % systems    <SUP># systems     % systems

----------------------------------------------------------------------------------------------------------------

No Further Treatment......................................        1,549          30          1,549          30

Number of Affected Systems................................        3,615          70          3,615          70

Treatment:

    Chlorine/Chloramine...................................          155           3.0          826          16.0

    Enhanced Coagulation..................................        2,169          42.0        1,983          38.4

    Enhanced Coagulation/Chloramine.......................          465           9.0          465           9.0

    Ozone/Chloramine......................................          258           5.0          184           3.6

    Enhanced Coagulation+Ozone, Chloramine................          258           5.0            0           0

    Membranes.............................................          310           6.0          157           3.0

----------------------------------------------------------------------------------------------------------------



    Table IV-3 illustrates the compliance forecast for ground water

systems. This forecast did not change from the time of proposal. A

smaller percentage of small ground water systems are anticipated to

need treatment changes (12 percent) than large ground water systems (15

percent) because the use of disinfectants is more prevalent in large

versus small ground water systems.



                       Table IV-3.--Compliance Decision Tree for All Ground Water Systems

----------------------------------------------------------------------------------------------------------------

                                                                   Systems <10,000          Systems <gr-thn-

                                                             --------------------------         eq>10,000

                                                                                       -------------------------

                                                               # systems    % systems    # systems    % systems

----------------------------------------------------------------------------------------------------------------

No Further Treatment........................................       59,847           88        1,122           85

Percentage of Affected Systems..............................        8,324           12          198           15

Treatment:

    Chlorine/Chloramine.....................................        5,403            8          119            9

    Ozone/Chloramine........................................            0            0           26            2

    Membranes...............................................        2,921            4           53            4

----------------------------------------------------------------------------------------------------------------



2. System Level Unit Costs

    Tables IV-4 and IV-5 present the unit cost estimates in 1998

dollars that were utilized for each of the different treatment

technologies in each system size category. Unit costs are presented in

$ per 1000 gallons which includes operation and maintenance costs and

amortized capital costs (using a 7% discount rate and a 20 year

amortization period). One dollar per thousand gallons equates to

approximately $100 per household per year as an average for communities

in the U.S. More detailed information on these unit costs is available

from the EPA's Cost and Technology Document (EPA, 1998k).



                                              Table IV-4.--Surface Water Systems Costs for DBP Control Technologies ($/Kgal) at 7% Cost of Capital

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

                                                                                                                   Population size category

                                                             -----------------------------------------------------------------------------------------------------------------------------------

                                                                25-100    100-500     500-1K     1-3.3K    3.3-10K     10-25K     25-50K     50-75K    75-100K   100K-500K   500K-1M      >1M

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Chlorine/Chloramine.........................................       0.71       0.19       0.06       0.03       0.03       0.02       0.01       0.01       0.01       0.01       0.01       0.01

Enhanced Coagulation (EC)...................................       0.15       0.13       0.12       0.11       0.09       0.08       0.07       0.07       0.07       0,07       0.06       0.06

EC/Chloramine...............................................       0.87       0.32       0.18       0.14       0.12       0.09       0.08       0.08       0.08       0.07       0.07       0.07

Ozone/Chloramine............................................      12.67       3.21       1.05       0.52       0.38       0.23       0.13       0.10       0.08       0.06       0.04       0.04

EC+Ozone, Chloramine........................................      12.82       3.34       1.17       0.63       0.47       0.30       0.20       0.17       0.15       0.13       0.11       0.10

EC+GAC10....................................................       6.24       2.43       1.21       0.81       0.59       0.46       0.37       0.35       0.29       0.24       0.19       0.16

EC+GAC20....................................................      14.11       5.87       3.45       2.45       1.87       1.48       1.05       1.00       0.90       0.64       0.48       0.41

Chlorine Dioxide............................................      24.33       5.73       1.65       0.64       0.24       0.11       0.07       0.07       0.06       0.05       0.04       0.04

Membranes...................................................       3.40       3.47       3.39       2.65       1.72       0.96       0.96       0.87       0.87       0.87       0.87       0.87

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------





                                               Table IV-5.--Ground Water Systems Costs for DBP Control Technologies ($/Kgal) at 7% Cost of Capital

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

                                                                                                                   Population size category

                                                             -----------------------------------------------------------------------------------------------------------------------------------

                                                                25-100    100-500     500-1K     1-3.3K    3.3-10K     10-25K     25-50K     50-75K    75-100K   100K-500K   500K-1M      >1M

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Chlorine/Chloramine.........................................       0.72       0.19       0.06       0.03       0.03       0.02       0.01       0.01       0.01       0.01       0.01       0.01

Ozone/Chloramine............................................      12.67       3.21       1.05       0.52       0.38       0.23       0.13       0.10       0.08       0.06       0.04       0.04

Membranes...................................................       3.41       3.47       3.39       2.65       1.72       0.96       0.96       0.87       0.87       0.87       0.87       0.87

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



3. National Costs

    Table IV-6 provides a detailed summary of national costs in 1998

dollars under the Stage 1 DBPR for different cost of capital

assumptions under a 20 year amortization period. A cost of capital rate

of 7 percent was used to calculate the unit costs for the national

compliance cost model. This rate represents the standard discount rate

preferred by OMB for benefit-cost analyses of government programs and

regulations. The 3 percent and 10 percent rates are provided as a

sensitivity analysis to show different assumptions about the cost of

capital that would affect estimated



[[Page 69437]]



costs. The 10 percent rate also provides a link to the 1994 Stage 1

DBPR cost analysis which was based on a 10 percent rate. EPA believes

that the cost estimates presented in Table IV-6 are probably within +/

-30 percent. Uncertainty around the cost estimates pertain to

compliance forecast estimates, unit cost estimates for the different

technologies as they may pertain to individual sites, and estimated

costs associated with monitoring.



                                               Table IV-6.--Summary of Costs Under the Stage 1 DBPR ($000)

--------------------------------------------------------------------------------------------------------------------------------------------------------

                                                                       Surface water systems                   Ground water systems

                       Utilities Costs                        ------------------------------------------------------------------------------ All systems

                                                                  Small        Large        Total        Small        Large        Total

--------------------------------------------------------------------------------------------------------------------------------------------------------

                                                      Summary of Costs at 3 Percent Cost of Capital

--------------------------------------------------------------------------------------------------------------------------------------------------------

                       Treatment Costs



Total Capital Costs..........................................      242,652      554,564      797,216      997,537      528,539    1,526,076    2,323,292

Annual O&M...................................................       23,068      201,308      224,376       83,910       54,243      137,153      362,530

Annualized Capital Costs.....................................       16,326       37,161       53,487       67,287       35,618      102,905      156,392

Annual Utility Treatment Costs...............................       39,394      238,469      277,863      151,197       89,861      240,058      518,922

Monitoring and Reporting Cost:

    Start-Up Costs...........................................           59           28           87          674           26          700          787

    Annual Monitoring........................................       10,867       14,619       25,486       38,803       26,326       65,129       90,615

State Costs:

    Start-Up Costs...........................................  ...........  ...........  ...........  ...........  ...........  ...........        2,919

    Annual Monitoring........................................  ...........  ...........  ...........  ...........  ...........  ...........       13,243

                                                              ------------------------------------------------------------------------------------------

        Total Annual Costs at 3 Percent Cost of Capital......  ...........  ...........  ...........  ...........  ...........  ...........      626,486

--------------------------------------------------------------------------------------------------------------------------------------------------------

                                                      Summary of Costs at 7 Percent Cost of Capital

--------------------------------------------------------------------------------------------------------------------------------------------------------

Total Capital Costs..........................................      242,652      554,564      797,216      997,537      528,539    1,526,076    2,323,292

Annual O&M...................................................       23,068      201,308      224,376       83,910       54,243      137,153      362,530

Annualized Capital Costs.....................................       22,786       62,355       85,141       94,403       50,046      144,499      229,590

Annual Utility Treatment Costs...............................       45,855      263,663      309,518      178,313      104,289      282,602      592,120

Monitoring and Reporting Cost:

    Start-Up Costs...........................................           82           39          121          946           36          982        1,103

    Annual Monitoring........................................       10,867       14,619       25,486       38,803       26,326       65,129       90,615

--------------------------------------------------------------------------------------------------------------------------------------------------------

State Costs:

    Start-Up Costs...........................................  ...........  ...........  ...........  ...........  ...........  ...........        4,099

    Annual Monitoring........................................  ...........  ...........  ...........  ...........  ...........  ...........       13,243

                                                              ------------------------------------------------------------------------------------------

        Total Annual Costs at 7 Percent Cost of Capital......  ...........  ...........  ...........  ...........  ...........  ...........      701,180

--------------------------------------------------------------------------------------------------------------------------------------------------------

                                                     Summary of Costs at 10 Percent Cost of Capital

--------------------------------------------------------------------------------------------------------------------------------------------------------

Total Capital costs..........................................      242,652      554,564      797,216      997,537      528,539    1,526,076    2,323,292

Annual O&M...................................................       23,068      201,308      224,376       83,910       54,243      137,153      362,530

Annualized Capital Costs.....................................       28,423       74,639      103,062      117,328       62,522      179,850      282,912

Annual Utility Treatment Costs...............................       51,491      275,947      327,438      201,238      116,765      317,003      645,442

Monitoring and Reporting Cost:

    Start-Up Costs...........................................          102           48          150        1,177           45        1,222        1,372

    Annual Monitoring........................................       10,867       14,619       25,486       38,803       26,326       65,129       90,615

State Costs:

    Start-Up Costs...........................................  ...........  ...........  ...........  ...........  ...........  ...........        5,100

    Annual Monitoring........................................  ...........  ...........  ...........  ...........  ...........  ...........       13,243

                                                              ------------------------------------------------------------------------------------------

        Total Annual Costs at 10 Percent Cost of Capital.....  ...........  ...........  ...........  ...........  ...........  ...........      755,772

--------------------------------------------------------------------------------------------------------------------------------------------------------



    The total national costs of the final Stage 1 DBPR are less than

estimated in the RIA for the proposed rule in 1994. The estimated

capital costs of the 1994 proposal in 1998 dollars is $4.97 billion and

the total annual cost (assuming a 10 percent cost of capital as was

assumed in 1994) is $1.3 billion. The drop in national costs from the

1994 proposal is mainly attributed to the lowering of the number of

surface water systems anticipated to need advanced technologies and

lower membrane technology costs as described above.



D. Benefits Analysis



1. Exposure Assessment

    A large portion of the U.S. population is exposed to DBPs via

drinking water. Over 200 million people in the U.S. are served by PWSs

which apply a disinfectant (e.g., chlorine) to water in order to

provide protection against microbial contaminants. Because of the large

number of people potentially exposed to DBPs, there is a substantial

concern for any health risks which may be associated with exposure to

DBPs.

    Several factors are necessary to assess the exposure to DBPs: the

size of the population potentially at risk; the method and rate of

ingestion; and the concentration of DBPs in drinking



[[Page 69438]]



water. Because DBPs are formed in drinking water by the reaction of

disinfectants with natural organic and inorganic matter, the population

at risk is identified as the population served by drinking water

systems that disinfect. The population served by each of four system

categories, taken from recent Safe Drinking Water Act Information

System data (SDWIS) is estimated in Table IV-7. Based on recent

information from SDWIS, it was assumed that all surface water systems

disinfect and a portion of ground water systems disinfect (95 percent

by population among large systems and 83 percent by population among

small systems). Approximately 239 million persons are estimated to be

served by water systems that disinfect and are potentially exposed to

DBPs. This widespread exposure represents over 88 percent of the total

U.S. population (270 million). The route of exposure is through

drinking disinfected tap water.



                               Table IV-7.--Population Potentially Exposed to DBPs

----------------------------------------------------------------------------------------------------------------

                                                                                       % of

                                                                                    population      Population

                                                                    Population       receiving       served by

                                                                      served        disinfected    systems that

                                                                                       water         disinfect

----------------------------------------------------------------------------------------------------------------

Large Surface Water: >10,000 persons............................     141,297,000             100     141,297,000

Small Surface Water: <10,000 persons............................      17,232,000             100      17,232,000

Large Ground Water: >10,000 persons.............................      56,074,000              95      53,270,300

Small Ground Water: < 10,000 persons............................      32,937,000              83      27,337,710

                                                                 -----------------------------------------------

    Total.......................................................  ..............  ..............     239,137,010

----------------------------------------------------------------------------------------------------------------



    In general, little data are available on the occurrence of DBPs on

a national basis. Although there is sufficient occurrence data

available for THMs in large water systems to develop a national

occurrence distribution for that subset of systems, data are limited

for small water systems. Similarly, some occurrence data for HAA5 are

available for large surface water systems, but not small surface water

and groundwater systems.

2. Baseline Risk Assessment Based on TTHM Toxicological Data

    EPA performed a quantitative risk assessment using the dose-

response information on THMs. This assessment, however, captures only a

portion of the potential risk associated with DBPs in drinking water.

It is not possible, given existing toxicological and exposure data, to

gauge how much of the total cancer risk associated with the consumption

of chlorinated drinking water is posed by TTHMs alone. An assessment of

THMs, however, provides some estimation of the potential human risk,

albeit limited.

    Performing the risk assessment based on TTHM toxicological data

requires making several assumptions and extrapolations (from a nonhuman

species to humans, from high doses in the laboratory study to lower

environmental exposures, and from a nondrinking water route to the

relevant route of human exposure). Assumptions are also made about the

occurrence of TTHMs and the individual DBPs. EPA estimated the pre-

Stage 1 DBPR TTHM concentration levels by calculating a weighted

average (based on populations receiving disinfected waters) of TTHM

levels among the different system type categories described in Table

IV-7. TTHM levels among systems serving greater than 10,000 people were

estimated based on average concentrations among systems in AWWA's WIDB.

TTHM levels in systems serving less than 10,000 people were estimated

through modeling. Modeling consisted of applying TTHM predictive

equations to estimates of DBP precursor levels and treatment

conditions. The mean weighted average baseline TTHM concentrations

among all the system type categories was 44 <greek-m>g/L.

    Occurrence data from an EPA DBP field study indicate that

chloroform is the most common THM (in general, about 70 percent of

total THMs), with bromoform being the least common (1 percent).

Bromodichloromethane has an occurrence of approximately 20 percent of

the total THMs, with dibromochloromethane comprising the final 8

percent of the total THMs. In the absence of more detailed occurrence

data, these proportions are used to divide the average TTHM

concentration into the concentration for the four individual compounds.

    Two estimates of risk factors were used to estimate the cancer

incidence. The first set of lifetime unit risk factors represent the

upper 95 percent confidence limit of the dose-response function. The

second estimate of lifetime unit risk is the maximum likelihood

estimate used in the 1994 analysis that represents the central tendency

of the dose-response function (Bull, 1991). The annual unit risk is

calculated by dividing the lifetime risk by a standard assumption of 70

years per lifetime. To calculate the annual incidence of cancer due to

consumption of TTHMs in drinking water, the annual drinking water unit

risk is multiplied by the number of units, in this case the

concentration of TTHMs in <greek-m>g/L, broken out into individual THMs

based on the proportions presented above. Based on these cancer risk

estimates derived from laboratory animal studies, the annual 95th

percentile upper bound number of cancer cases attributable to TTHMs is

approximately 100. This means that there is a 95 percent chance that

the annual number of cases are less than or equal to 100. Using the

maximum likelihood or ``best'' estimates, the annual number of cancer

cases is about 2.

3. Baseline Analysis Based on Epidemiology Data

    Epidemiological studies can be used to assess the overall

population risk associated with a particular exposure. Since the late

1970s, epidemiological investigations have attempted to assess whether

chlorinated drinking water contributes to the incidence of bladder,

colon, rectal, and other cancers. Several studies have reported a weak

association between bladder cancer and exposure to chlorinated drinking

water, but a causal relationship has not been confirmed (Freedman, et

al., 1997).

    Several cancer epidemiological studies examining the association

between exposure to chlorinated surface water and cancer were published

subsequent to the 1994 proposed rule and the 1992 meta-analysis. In

general, these new studies are better designed than the studies

published prior to the 1994 proposal. The new studies include incidence

of disease, interviews with the study subjects, and better exposure

assessments. More evidence is available



[[Page 69439]]



on bladder cancer for a possible association to exposure to chlorinated

surface water than other cancer sites. Because of the limited data

available for other cancer sites such as colon and rectal cancer, the

RIA focuses on bladder cancer.

    Based on the best studies, a range of potential risks was developed

through the use of the population attributable risk (PAR) concept.

Epidemiologists use PAR to quantify the fraction of disease burden in a

population (e.g., bladder cancer) that could be eliminated if the

exposure (e.g., chlorinated drinking water) was absent. PAR (also

referred to as attributable risk, attributable portion, or etiologic

fraction) provides a perspective on the potential magnitude of risks

associated with various exposures under the assumption of causality.

For example, the National Cancer Institute estimates that there will be

54,500 new cases of bladder cancer in 1997. If data from an

epidemiological study analyzing the impact of consuming chlorinated

drinking water reports a PAR of 1 percent, it can be estimated that 545

(54,500  x  .01) bladder cancer cases in 1997 may be attributable to

chlorinated drinking water.

    Under the Executive Order #12866 that requires EPA to conduct a

RIA, EPA has chosen to estimate an upper bound bladder cancer risk

range for chlorinated drinking water using the PAR. EPA suggested this

approach in the 1998 NODA (EPA, 1998a). While EPA recognizes the

limitations of the current epidemiologic data base for making these

estimates, the Agency considers the data base reasonable for use in

developing an upper bound estimate of bladder cancer risk for use in

the RIA. In light of the toxicological evidence, EPA recognizes that

the risks from chlorinated drinking water may be considerably lower

than those derived from the currently available epidemiological

studies. EPA selected studies for inclusion in the quantitative

analysis if they contained the pertinent data to perform a PAR

calculation and met all three of the following criteria:

    1. The study was a population-based, case-control, or cohort study

conducted to evaluate the relationship between exposure to chlorinated

drinking water and incidence of cancer cases, based on personal

interviews; (all finally selected studies were population-based, case-

control studies)

    2. The study was of high quality and well designed (e.g., adequate

sample size, high response rate, adjusted for known confounding

factors); and,

    3. The study had adequate exposure assessments (e.g., residential

histories, actual THM data).

    Using the above criteria, five bladder cancer studies were selected

for estimating the range of PARs.

    <bullet> Cantor, et al., 1985;

    <bullet> McGeehin, et al., 1993;

    <bullet> King and Marrett, 1996;

    <bullet> Freedman, et al., 1997; and

    <bullet> Cantor, et al., 1998.

    The PARs from the five bladder cancer studies ranged from 2 percent

to 17 percent. These values were derived from measured risks (Odds

Ratio and Relative Risk) based on the number of years exposed to

chlorinated surface water. Because of the uncertainty in these

estimates, it is possible that the PAR could also be zero. The

uncertainties associated with these PAR estimates are large due to the

common prevalence of both the disease (bladder cancer) and exposure

(chlorinated drinking water).

    In order to apply these PAR estimates to the U.S. population to

estimate the number of bladder cancer cases attributable to DBPs in

drinking water, a number of assumptions must be made. These include:

(1) that the study populations selected for each of the cancer

epidemiology studies are reflective of the entire population that

develops bladder cancer; (2) that the percentage of those cancer cases

in the studies exposed to chlorinated drinking water are reflective of

the bladder cancer cases in the U.S.; (3) that DBPs were the only

carcinogens in these chlorinated surface waters; and (4) that the

relationship between DBPs in chlorinated drinking water exposure and

bladder cancer is causal.

    The last of these assumptions is perhaps the most open to question.

As noted in the March 1998 NODA, the results of the studies are

inconsistent. In light of these concerns, the Agency agrees that

causality between exposure to chlorinated water and bladder cancer has

not been established and that the number of cases attributable to such

exposures could be zero.

    Based on the estimate of 54,500 new bladder cancer cases per year

nationally, as projected by the National Cancer Institute for 1997, the

numbers of possible bladder cancer cases per year potentially

associated with exposures to DBPs in chlorinated drinking water

estimated from the five studies range from 1,100 (0.02  x  54,500) to

9,300 (.17  x  54,500) cases. As noted above, due to the uncertainty in

these estimates, the number of cases could also be zero. In making

these estimates it is necessary to assume that these bladder cancer

cases are attributed to DBPs in chlorinated surface water, even though

the studies examined the relationship between chlorinated surface water

and bladder cancer. This derived range is not accompanied by confidence

intervals (C.Is), but the C.Is. are likely to be very wide. EPA

believes that the mean risk estimates from each of the five studies

provides a reasonable estimate of the potential range of risk suggested

by the different epidemiological studies. Table IV-8 contains a summary

of the risk estimates from the 1994 draft RIA and the estimates derived

from the more recent analysis.

    A related analysis based on odds ratios was conducted to derive a

range of plausible estimates for cancer epidemiologic studies (EPA,

1998n). This analysis was also based on bladder cancer studies (the

five studies cited above in addition to Doyle et al. 1997). For the

purpose of this exercise, the annual U.S. expected number of 47,000

bladder cancers cited by Morris et al.(1992) was used to calculate

estimates of the cancers prevented. The number of cancers attributable

to DBP exposure was estimated not to exceed 2,200-9,900 per year and

could include zero. As would be expected from related analysis

performed in the same data, this range is similar to the 1,100-9300 PAR

range. EPA has used the 1100-9300 PAR range for the RIA.



                           Table IV-8.--Number of Cancer Cases Attributable to DBPs: Comparison of Estimates in 1994 and 1998

--------------------------------------------------------------------------------------------------------------------------------------------------------

                                                         1994 estimates                                          1998 estimates

--------------------------------------------------------------------------------------------------------------------------------------------------------

Number of New Bladder Cancer Cases/Year.  Approx. 50,000..............................  54,500.

Number of Estimated Deaths Due to         Did not state...............................  12,500.

Bladder Cancer/Year.



Attributable to DBPs in Drinking Water



Data Source.............................  >15 studies.................................  5 studies that meet specific criteria.

Causality...............................  No..........................................  No.

Percent Attributable to DBPs............  Did not state...............................  2% to 17%.



[[Page 69440]]





Number of Cancer Cases Attributable to

DBPs:

    Estimated Using Toxicological Data..  Less than 1*................................  Zero to 100.**

    Estimated Using Epidemiological Data  Over 10,000***..............................  Zero to 9,300.****

--------------------------------------------------------------------------------------------------------------------------------------------------------

* Based on maximum likelihood estimates of risk from THMs.

** Based on IRIS 95th percent C.I. estimates of risk from THMs.

*** Indicates rectal and bladder cancer cases.

**** Indicates only bladder cancer cases.



    The current benefits analysis is structured in roughly the same

manner as that presented in the 1994 RIA. The baseline cancer risks

could lie anywhere from zero to 100 cases per year based on

toxicological data; and zero to 9,300 cases per year based on

epidemiological data. Consequently, the task is to assess the economic

benefit of the final Stage 1 DBPR in the face of this broad range of

possible risk.

4. Exposure Reduction Analysis

    EPA predicted exposure reductions due to the current Stage 1 DBPR

relative to the present baseline. EPA used the concentration of TTHMs

as a marker to measure the exposure to the range of DBPs because data

are available on the baseline occurrence and formation of TTHMs. There

are limited data on the total mix of byproducts in drinking water.

Therefore, the reduction in TTHMs is assumed to reflect the reduction

in exposure to all DBPs. To determine the change in exposure, it is

necessary to estimate the pre-Stage 1 baseline average TTHM

concentration and the post Stage 1 average TTHM concentration. The

difference in the pre-and post-Stage 1 TTHM concentrations reflect the

potential reduction in TTHMs and thus in DBPs.

    As described previously, the estimated pre-Stage 1 TTHM weighted

average concentration is 44 <greek-m>g/L for all system sizes and types

of systems. The post Stage 1 TTHM concentrations for each system

category were estimated based on the technology compliance forecasts

previously discussed and estimated reductions in TTHM levels depending

upon technology. The post-Stage 1 TTHM weighted average concentration

is estimated at 33 <greek-m>g/L. This represents a 24 percent reduction

in TTHM levels resulting from the Stage 1 DBPR. Further details of the

above analysis is described in the RIA for the Stage 1 DBPR (USEPA,

1998g).

5. Monetization of Health Endpoints

    The range of potential benefits from the Stage 1 DBPR can be

estimated by applying the monetary values for fatal and nonfatal

bladder cancer cases with the estimate of the number of bladder cancer

cases reduced by the rule. The following assumptions are used to

estimate the range of potential benefits:

    <bullet> An estimate of the number of bladder cancer cases

attributable to DPBs in drinking water ranging from 0 to 9,300

annually.

    <bullet> A 24 percent reduction in exposure to TTHMs due to the

Stage 1 DBPR (75 percent CI of 19 to 30 percent) will result in an

equivalent reduction in bladder cancer cases

    <bullet> A value per statistical life saved for fatal bladder

cancers represented by a distribution with a mean of $5.6 million

    <bullet> A willingness to pay to avoid a nonfatal case of bladder

cancer represented by a distribution with a mean of $587,500

    Using the low end of the risk range of 0 bladder cancer cases

attributable to DBPs results in a benefits estimate of $0. To calculate

the high end of the range, the 9,300 estimate of attributable cases is

multiplied by the percent reduction in exposure to derive the number of

bladder cancer cases reduced (9,300  x  .24 = 2,232 bladder cancer

cases reduced). This assumes a linear relationship between reduction in

TTHMs concentrations and reduction in cancer risk (e.g., 24 percent

reduction in TTHMs concentration is associated with a 24 percent

reduction in cancer risk). Assuming 23 percent of the bladder cancer

cases end in fatality and 77 percent are nonfatal, the number of fatal

bladder cancer cases reduced is 513 (2,232  x  .23) and the number of

nonfatal bladder cancer cases is 1,719 (2,232  x  .77). Based on the

valuation distributions described above, the estimate of benefits at

the mean associated with reducing these bladder cancer cases is

approximately $4 billion. It should be noted that these estimates do

not include potential benefits from reducing other health effects (e.g,

colon/rectal cancer and reproductive endpoints) that cannot be

quantified at this time. As a result, EPA believes that the potential

benefits discussed in today's rule may be a substantial underestimate

of potential benefits that will be realized as a consequence of today's

action. While the low end of the range cannot extend below $0, it is

possible that the high end of the range could extend beyond $4 billion

if the other reductions in risk could be quantified and monetized. No

discount factor has been applied to these valuations, although there is

likely to be a time lag between compliance with the rule and the

realization of benefits.

    Given this wide range of potential benefits and the uncertainty

involved in estimating the risk attributable to DBPs, EPA undertook

five different approaches to assessing the net benefits of the Stage 1

DBPR. These approaches are described in the net benefits section and

should be considered both individually and in the aggregate.



E. Net Benefits Analysis



    The potential economic benefits of the Stage 1 DBPR derive from the

increased level of public health protection and associated decreased

level of risk. The quantification of the benefits resulting from DBP

control is complicated by the uncertainty in the understanding of the

health risks. Epidemiological studies, referred to previously, suggest

an association between bladder cancer and exposure to chlorinated

surface water; however, these risks are uncertain. The lowest estimate

in the selected epidemiological studies of the number of new bladder

cancer cases per year attributable to chlorinated surface water is

1,100 cases, while the highest is 9,300 cases. EPA recognizes that

while these risks may be real, they also could be zero. Assessment of

risks based only on toxicological data for THMs, indicate a much lower

risk (2 cancer cases per year at the most likely estimate, to about 100

cases per year using the 95 percent confidence level upper bound), but

THMs represent only a few of the many DBPs in drinking water.

    EPA explored several alternative approaches for assessing the

benefits of the Stage 1 DBPR: Overlap of Benefit and Cost Estimates;

Minimizing Total Social Losses; Breakeven Analysis;



[[Page 69441]]



Household Costs; and Decision-Analytic Model. A summary of the analysis

of each approach is presented below. More detailed descriptions are

described in the RIA (USEPA, 1998g).

    Overlap of Benefit and Cost Estimates. One method to characterize

net benefits is to compare the relative ranges of benefits and costs.

Conceptually, an overlap analysis tests whether there is enough of an

overlap between the range of benefits and the range of costs for there

to be a reasonable likelihood that benefits will exceed costs. In a

theoretical case where the high end of the range of benefits estimates

does not overlap the low end of the range of cost estimates, a rule

would be difficult to justify based on traditional benefit-cost

rationale.

    For the Stage 1 DBPR, the overlap analysis (Figures IV-1a and IV-

1b) show that there is substantial overlap in the estimates of benefits

and costs. The range of quantified benefits extends from zero to over

$4 billion. The zero end of the range of estimated benefits represents

the possibility that there is essentially no health benefit from

reducing exposure to DBPs. The other end of the range assumes there are

9,300 bladder cancer cases per year attributable to DBPs and there is a

24 percent annual reduction in exposure with the promulgation of the

rule, resulting in avoidance of 2,232 cases. Assuming that number of

avoided cases, approximately 513 would have been fatalities and would

result in a cost savings of approximately $3 billion (each avoided

fatality results in a cost savings of $5.6 million). Additionally,

1,719 non-fatal cases avoided would result in a cost savings of

approximately $1 billion (each avoided non-fatal case results in a cost

savings of $0.6 million). The sum of the cost savings is approximately

$4 billion. The high end of the benefits range could potentially be

higher if other health damages are avoided. The range of cost estimates

is significantly smaller, ranging from $500 million to $900 million

annually. Although these cost estimates have uncertainty, the degree of

uncertainty is of little consequence to the decisions being made given

the scale of the uncertainty for the benefits.

    Figure IV-1b, on the other hand, indicates that while the

quantified benefits could exceed the costs, there is the possibility

that there could be negative net benefits if there were no health

benefits.



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Figure IV-1a Overlap of Estimated Benefits and Costs of the Stage 1

DBPR



    Figure IV-1b Overlap of the Ranges of the Estimated Benefits and

Costs of the Stage 1 DBPR

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    Minimizing Total Social Losses Analysis. Minimizing Total Social

Losses analysis, sometimes called ``minimizing regrets'' analysis, is a

decision-aiding tool that is suited for use in situations where it is

impossible to pin down the exact nature and extent of a risk. The basic

premise of Minimizing Total Social Losses analysis is to estimate total

social costs for policy alternatives over a range of plausible risk

scenarios. The actual, or ``true'' risk is unknowable, so instead this

analysis asks what range and level of risks could be true, and then

evaluates the total costs to society if particular risk levels within

that range turned out to be the ``true'' value. Total social costs

include both the cost to implement the policy option, plus costs

related to residual (i.e., remaining) health damages at each risk level

after implementation of the policy option.

    Under this analysis the ``total social costs'' (water treatment

costs plus costs of health damages still remaining after treatment) are

calculated for three regulatory alternatives (No Action, Stage 1, and

Strong Intervention--otherwise known as the proposed Stage 2

requirements of the 1994 proposal) across a range of risk scenarios (<

1; 100; 1,000; 2,500; 5,000; 7,500; and 10,000 attributable bladder

cancer cases annually). Total social costs for each regulatory

alternative for different risk assumptions are presented in Table IV-9.

The results indicate that the Stage 1 DBPR has the least social cost

among the three alternatives analyzed across the range of risks from

2,500 through 7,500 attributable bladder cancer cases annually.

    Total ``social loss'' for each risk scenario are also indicated in

Table IV-9. The ``social loss'' is the cost to society of making a

wrong choice among the regulatory alternatives. It is computed as the

difference between the total social cost (water treatment cost plus

remaining health damages) of an alternative at a given risk scenario

and the total social cost of the best alternative (least total social

cost alternative for that risk scenario). The regulatory alternatives

across the different risk levels can also be compared to see which

alternative minimizes the maximum potential loss. The best alternative,

by this ``mini-max'' criteria, would be the one in which the upper

bound of potential losses is smallest.



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    Under the Stage 1 DBPR alternative, the worst loss that could

happen would occur if the lowest end of the risk range is true. This

would result in total social losses of $0.7 billion per year. It is

concluded that the maximum potential loss of the Stage 1 alternative is

smaller than that of No Action ($4.1 billion) by a factor of 6 and

smaller than that of Strong Intervention ($2.9 billion) by a factor of

4. Thus, the Stage 1 DBPR is the best of the 3 alternatives at

minimizing the maximum social loss.

    The 1994 Reg. Neg. and 1997 M-DBP Advisory Committees implicitly

applied this type of ``minimizing maximum loss'' framework when

developing and evaluating the DBP regulatory options. In the face of

large uncertainty regarding risk from DBPs, they decided that a

moderate response, relying on the more cost-effective of the available

treatment methods was appropriate as an interim step until more

information on risk becomes available.

    Break Even Analysis. Breakeven analysis represents another approach

to assessing the benefits of the Stage 1 DBPR given the scientific

uncertainties. Breakeven is a standard benchmark of cost effectiveness

and economic efficiency, and is essentially the point where the

benefits of the Stage 1 DBPR are equal to the costs. Normally, the

benefits and costs of an option are calculated separately and then

compared to assess whether and by what amount benefits exceed costs. In

the case of the Stage 1 DBPR, independently estimating benefits is

difficult, if not impossible, because of the 10,000-fold uncertainty

surrounding the risk. Instead, the breakeven analysis works backwards

from those variables that are less uncertain. In this case,

implementation costs for the rule and the monetary value associated

with the health endpoints are used to calculate what baseline risk and

risk reduction estimates are needed in order for the benefits, as

measured in avoided health damages associated with bladder cancer, to

equal the costs.

    Two important concepts for this analysis are the cost of illness

measure and the willingness-to-pay measure. The cost of illness measure

includes medical costs and lost wages associated with being unable to

work as a result of illness. In comparison, willingness-to-pay measures

how much one would pay to reduce the risk of having all the discomfort

and costs associated with nonfatal cancer if such an option existed.

The main difference between these two methods is that willingness-to-

pay incorporates pain and suffering, as well as changes in behavior

into the valuation, while cost of illness does not. EPA has estimated

the cost of a non-fatal case of bladder cancer at $121,000 using the

cost of illness method, and at $587,500 using the willingness-to-pay

approach.

    Assuming an annual cost of $701 million and assumptions about the

monetary value of preventing both fatal and nonfatal bladder cancer

cases, the Stage 1 DBPR would need to reduce 438 bladder cancer cases

per year using the willingness-to-pay measure for nonfatal cancers or

574 cases per year using the cost of illness measure. If exposure is

reduced by 24 percent, the baseline number of bladder cancer cases

attributable to DBPs in chlorinated drinking water required to break

even would need to range from 1,820 to 2,390 new cases annually.

Although these values are well above the range indicated by existing

toxicological data for THMs alone, they fall within the attributable

risk range suggested by the epidemiological studies.

    Household Cost Analysis. A fourth approach for assessing the net

benefits of the Stage 1 DBPR is to calculate the costs per household

for the rule. Household costs provide a common sense test of benefit/

cost relationships and are another useful benchmark for comparing the

willingness-to-pay to reduce the possible risk posed by DBPs in

drinking water. It is essentially a household level breakeven analysis.

It works backwards from the cost to ask whether the implied amount of

benefits (willingness-to-pay) needed to cover costs is a plausible

amount.

    About 115 million households are located in service areas of

systems affected by the Stage 1 DBPR. Of these households, 71 million

(62 percent) are served by large surface water systems. Approximately

4.2 million (4 percent) are served by small surface water systems.

Large ground water systems served 24 million households (21 percent)

and small ground water systems serve 15.7 million households (14

percent).

    All of the households served by systems affected by the Stage 1

DBPR will incur some additional costs (e.g., monitoring costs), even if

the system does not have to change treatment to comply with the

proposed rule. The costs calculated below include both monitoring and

treatment costs.

    The cumulative distribution of household costs for all systems and

by each system type is displayed in Figures IV-2a, IV-2b, IV-2c. The

distributions show that the large percentage of households will incur

small additional costs, with a small portion of systems facing higher

costs. At the highest end of the distribution, approximately 1,400

households served by surface water systems in the 25-100 size range

switching to membrane technology will face an average annual cost

increase of $400 per year ($33 per month).



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    The households have been sorted into three cost categories for the

ease of comparison (Table IV-10). The first category includes

households with a cost increase of less than $12 per year, less than $1

per month. The second category contains households with costs greater

than $12 per year, but less than $120 per year ($10 per month). The

third category includes households with cost increases greater than

$120 per year to $400 per year ($33 per month).

    Across all system categories (see Figure IV-2a), 95 percent of the

households (110.1 million) fall within the first category and will

incur less than $1 per month additional costs due to the Stage 1 DBPR.

An additional 4 percent (4.4 million) are in the second category at

between $1 and $10 per month cost increase and 1 percent (1.0 million)

are in the highest category ($10-$33.40 per month).

    For households served by large surface water systems (Figure IV-

2b), 98 percent will incur less than $1 per month, 2 percent will incur

between $1 and $10 per month, and 0.03 percent will incur greater than

$10 per month. The highest cost ($125 annually, $10.40 monthly) is

faced by households served by systems in the 10,000 to 25,000 size

range implementing membrane technology.

    For households served by small surface water systems (Figure IV-

2c), 71 percent will incur less than $1 per month, 28 percent will

incur between $1 and $10 per month, and 1 percent will incur greater

than $10 per month. The highest cost ($400 annually, $33 monthly) is

faced by households served by systems in the 25-100 size range

implementing membrane technology.

    For households served by large ground water systems (Figure IV-2b),

95 percent will incur less than $1 per month, 4 percent will incur

between $1 and $10 per month, and 1 percent will incur greater than $10

per month. The highest cost ($125 annually, $10.40 monthly) is faced by

households served by systems in the 10,000 to 25,000 size range

implementing membrane technology.

    For households served by small ground water systems (Figure IV-2c),

91 percent will incur less than $1 per month, 5 percent will incur

between $1 and $10 per month, and 4 percent will incur greater than $10

per month. The highest cost ($357 annually, $29.75 monthly) is faced by

households served by systems in the 25-100 size range implementing

membrane technology.



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    In the small proportion of systems where household costs are shown

to be much greater--up to several hundreds of dollars per year--these

results are driven by the assumption that membrane technologies will be

the selected treatment, as noted above. Additionally, two points must

be made: (1) a number of these systems may find less expensive means of

compliance (e.g., selection of alternative source water, purchased

water, or consolidation with other systems); and (2) if these systems

do install membranes, they may receive additional water quality and/or

compliance benefits beyond those associated with DBPs. For example,

because membranes are so effective, systems that install membranes are

likely to incur lower compliance costs for future rulemakings.

    Given the uncertain nature of the risks associated with DBPs,

household costs provide a common sense estimate of willingness-to-pay

to reduce the risks: Would the average household (95 percent of

households) be willing to pay less than $1 per month ($12 per year) to

reduce the potential risks posed by DBPs?

    Willingness to pay studies are not available to directly answer

this question. Taking the $1 per month figure as a measure of implied

public health benefit at the household level, it is useful to ask what

benefits can be identified that could balance a $1 per month

expenditure. First, it is entirely possible that there is much more

than a dollar-a-month's worth of tangible health benefit based on

reduced risk of bladder cancer alone. Second, the broad exposure to

DBPs and the possible health effects involved offer the possibility

that there are significant additional health benefits of a tangible

nature. However, the agency recognizes that in the small percentage of

situations where the costs per household is between $120 to $400 per

year, this may indeed be a difficult financial burden to meet (e.g.,

may exceed household willingness-to-pay).

    Finally, the preventive weighing and balancing of public health

protection also provides a margin of safety--a hedge against

uncertainties. Recent survey research conducted in the drinking water

field provides compelling empirical evidence that the number one

priority of water system customers is the safety of their water.

Although definitive economic research has not been performed to

investigate the extent of household willingness-to-pay for such a

margin of safety, there is strong evidence from conventional customer

survey research implying a demand for this benefit.

    Decision Analytical model. The RIA also discusses a fifth type of

analysis in which probability functions are used to model the

uncertainty surrounding three variables (rule cost, exposure reduction,

and attributable bladder cancer risk) in order to derive a probability

distribution function for annual net benefit of the Stage I rule.

Because there is little actual data on these probability functions,

this approach should be considered illustrative only. It is not

discussed further here, but is discussed in Chapter 6 of the RIA for

the Stage 1 DBPR (EPA, 1998g).

    While any one of the above analytical approaches by itself may not

make a definitive case for the benefit-cost effectiveness for the Stage

1 DBPR, taken collectively EPA believes they indicate that the Stage 1

DBPR benefits to society will exceed the costs. The monetized benefits

in the five alternatives represent only a portion of total potential

benefits. Benefits associated with other cancer sites (rectal and

colon) and other health endpoints (such as developmental and

reproductive effects) could not be quantified at this time, and while

they could be nil, they also could be quite large. Based on a careful

weighing of the projected costs against the potential quantified and

non-quantified benefits, EPA has determined that the benefits of the

rule justify its costs.



F. Summary of Comments



    Many commenters expressed concern about the wide range of benefits

given the high national cost of the rule. EPA has revised the benefits

analysis; and while the associated uncertainties remain large, EPA

believes the benefits of the Stage 1 DBPR justify its costs.

    Other commenters expressed concern with using the data from Morris

et al. (1992) for quantifying benefits. They believed that the studies

used in the meta-analysis were different in design and thus not

appropriate to use in meta-analysis. In addition the commenters

believed that potential confounding factors or bias may not have been

adequately controlled in the selected studies. Others believed there

was utility in using the meta-analysis to provide a perspective on the

potential cancer risks. Several commenters were supportive of the Poole

(1997) evaluation of the Morris et al. (1992) meta-analysis stating

that they concurred that the Morris analysis should not be used for

estimating benefits for the Stage 1 DBPR. Other commenters suggested a

better use of the resources used to complete the Poole report would

have been to complete a new meta-analysis using the more recent studies

that have come out since the Morris et al. (1992) meta-analysis and

that the Poole evaluation did not advance the science in this area.

Several commenters were critical of the PAR analysis (described in EPA,

1998a) used to characterize the potential baseline bladder cancer cases

per year that could be attributable to exposure to chlorinated drinking

water. They present several arguments including: questioning whether

such an analysis is warranted given the inconsistencies in the studies

used to complete the analysis; stating that the use of the term upper

bound of any suggested risk of cancer is inappropriate because this

does not include the potential risks from other cancer sites such as

colon and rectal; using the assumption of causality is not warranted

given the inconsistencies in the studies used to complete the PAR

analysis; and the PAR analysis should include a lower bound estimate of

zero.

    EPA agrees that the use of the Morris et al. (1992) meta-analysis

for estimating benefits is not appropriate for the reasons cited by

commenters (e.g., studies of different designs and discussed in more

detail in the 1998 DBP NODA). EPA is currently considering whether a

new meta-analysis that uses the most recent epidemiology studies would

be useful for the Stage 2 rulemaking. The Poole (1997) report

considered a meta analysis of the available data. Poole used several

techniques to evaluate the data and included several new studies that

were available at the time of his analysis. Poole concluded that the

cancer epidemiology data considered in his evaluation should not be

combined into a single summary estimated and that the data had limited

utility for risk assessment purposes. More recent studies by Cantor et

al. (1998), Doyle et al. (1997) and Freedman et al. (1997) were not

available at the time of his evaluation.

    EPA understands commenters concerns with the PAR analysis,

especially concerns with assuming ``causality'' in the PAR evaluation

when it is stated in other sections of the preamble that EPA does not

believe causality has been established. Even though causality has not

been established, EPA is required to estimate the potential impacts of

major regulations such as the DBP Stage 1 rule. The Agency believes it

is appropriate to conduct the PAR analysis as described in the 1998 DBP

NODA (EPA, 1998a), to provide estimates of the



[[Page 69452]]



potential risk that may need to be reduced. EPA agrees that the use of

the term ``upper bound of any suggested risk'' is not appropriate

because there are other potential risks that have not been quantified

that may contribute to the overall risk estimates. In addition, EPA

agrees that the estimates of the potential cancer cases should include

zero as this is a possibility given the uncertainties in the data. EPA

agrees that several assumptions are made in the analysis regarding the

national extrapolation of the results and that there is insufficient

information at this time to validate these assumptions. However, given

the need to develop national estimates of risk, EPA believes it is

appropriate to make these assumptions in order to provide a perspective

on the potential risks from exposure to chlorinated surface waters.

    Commenters expressed concerns with the high costs associated with

systems that must adopt alternative advanced technologies, especially

for small systems. Since the 1994 proposal, the projected national

costs for the Stage 1 DBPR have dropped significantly (as discussed

above). This is mainly due to the revised compliance forecast and lower

membrane technology costs. In the revised compliance forecast, fewer

systems using surface water will need advanced technologies to comply.

This shift to lesser use of advanced technologies to comply with the

Stage 1 DBPR also pertains to small systems (those serving less than

10,000 people).

    Commenters expressed concern for the high costs associated with the

Stage 2 DBPR and whether EPA would obtain enough information to

adequately understand the risks that might be avoided to justify such a

rule. EPA agrees that additional health effects information is needed

before reproposing the Stage 2 DBPR and will address this issue in the

next round of FACA deliberations. Based on new data generated through

research, EPA will reevaluate the Stage 2 regulations and re-propose,

as appropriate.



V. Other Requirements



A. Regulatory Flexibility Act



1. Today's Rule

    Under the Regulatory Flexibility Act, 5 U.S.C. 601 et seq. (RFA),

as amended by the Small Business Regulatory Enforcement Fairness Act,

EPA generally is required to conduct a regulatory flexibility analysis

describing the impact of the regulatory action on small entities as

part of rulemaking. However, under section 605(b) of the RFA, if EPA

certifies that the rule will not have a significant economic impact on

a substantial number of small entities, EPA is not required to prepare

a regulatory flexibility analysis.

    Throughout the 1992-93 negotiated rulemaking process for the Stage

1 DBPR and IESWTR and in the July 1994 proposals for these rules, a

small PWS was defined as a system serving fewer than 10,000 persons.

This definition reflects the fact that the original 1979 standard for

total trihalomethanes applied only to systems serving at least 10,000

people. The definition thus recognizes that baseline conditions from

which systems serving fewer than 10,000 people will approach

disinfection byproduct control and simultaneous control of microbial

pathogens is different than that for systems serving 10,000 or more

persons. EPA again discussed this approach to the definition of a small

system for these rules in the 1998 DBP NODA (EPA, 1998a). EPA is

continuing to define ``small system'' for purposes of this rule and the

IESWTR as a system which serves fewer than 10,000 people.

    The Agency has since proposed and taken comment on its intent to

define ``small entity'' as a public water system that serves 10,000 or

fewer persons for purposes of its regulatory flexibility assessments

under the RFA for all future drinking water regulations. (See Consumer

Confidence Reports Rule, 63 FR 7620, Feb. 13, 1998.) In that proposal,

the Agency discussed the basis for its decision to use this definition

and to use a single definition of small public water system whether the

system was a ``small business'', ``small nonprofit organization'', or

``small governmental jurisdiction.'' EPA also consulted with the Small

Business Administration on the use of this definition as it relates to

small businesses. Subsequently, the Agency has used this definition in

developing its regulations under the Safe Drinking Water Act. This

approach is virtually identical to the approach used in the Stage 1

DBPR and IESWTR. Since, EPA is not able to certify that the final Stage

1 DBPR will not have a significant economic impact on a substantial

number of small entities, EPA has completed a final RFA and will

publish a small entity compliance guidance to help small entities

comply with this regulation.

2. Background and Analysis

    The Regulatory Flexibility Act requires EPA to address the

following when completing a final RFA: (1) state succinctly the

objectives of, and legal basis for, the final rule; (2) summarize

public comments on the initial RFA, the Agency's assessment of those

comments, and any changes to the rule in response to the comments; (3)

describe, and where feasible, estimate the number of small entities to

which the final rule will apply; (4) describe the projected reporting,

record keeping, and other compliance requirements of the rule,

including an estimate of the classes of small entities that will be

subject to the requirements and the type of professional skills

necessary for preparation of reports or records; and (5) describe the

steps the Agency has taken to minimize the impact on small entities,

including a statement of the reasons for selecting the chosen option

and for rejecting other options which would alter the impact on small

entities. EPA has considered and addressed all the above requirements

in the Regulatory Impact Analysis (RIA) for the Stage 1 DBPR (EPA

1998g). The following is a summary of the RFA.

    The first requirement is discussed in section I of today's rule.

The second, third and fifth requirements are summarized below. The

fourth requirement is discussed in V.B (Paperwork Reduction Act) and

the Information Collection Requirement.

    Number of Small Entities Affected. EPA estimates that 69,491

groundwater systems will be affected by the Stage 1 DBPR, with 68,171

(98%) of these systems serving less than 10,000 persons. Of the 68,171

small systems affected, EPA estimates that 8,323 (12%) will have to

modify treatment to comply with the Stage 1 DBPR. Of these, 5,403

systems (8%) will use chloramines to comply and 2,921 systems (4.3%)

will use membranes to comply. Use of these technologies by small

groundwater systems will result in total capital costs of $998 million

and an annualized treatment cost of $180 million.

    EPA estimates that 6,560 surface water systems will be affected by

the Stage 1 DBPR, with 5,165 (79%) of these systems serving less than

10,000 persons. It is estimated that 3,616 (70%) of these small systems

will have to modify treatment to comply with the Stage 1 DBPR and 3,459

(67%) of these systems will use a combination of enhanced coagulation,

chloramines, and ozone, while another 157 systems (3%) will use

membranes. Use of these technologies by small surface water systems

will result in total capital costs of $243 million and an annualized

treatment cost of $46 million.

    EPA has included several provisions which will reduce the economic

burden of compliance for these small systems. These requirements,

discussed in greater detail in the RIA (EPA, 1998g), include:





[[Page 69453]]





--Less routine monitoring. Small systems are required to monitor less

frequently for such contaminants as TTHMs and HAA5. Also, ground water

systems (the large majority of small systems) are required to monitor

less frequently than Subpart H systems (surface water systems and

groundwater under the direct influence of surface water) of the same

size.

--Extended compliance dates. Systems that use only ground water not

under the direct influence of surface water serving fewer than 10,000

people have 60 months from promulgation of this rule to comply. This is

in contrast to large Subpart H systems which have 36 months to comply.

These extended compliance dates will allow smaller systems to learn

from the experience of larger systems on how to most cost effectively

comply with the Stage 1 DBPR. In addition, larger systems will generate

a significant amount of treatment and cost data from the ICR and in

their efforts to achieve compliance with the Stage 1 requirements. EPA

intends to summarize this information and make it available through

guidance manuals (i.e., the Small Entities Guidance Manual). EPA

believes this information will assist smaller systems in achieving

compliance with the Stage 1 DBPR.

3. Summary of Comments

    Several commenters expressed concern with the significant economic

burden that the Stage 1 DBPR would place on small systems. Other

commenters suggested more flexibility be given for small systems and

that a longer compliance period for small systems should be included in

the final Stage 1 DBPR. Several commenters suggested small systems

should not be included in the final Stage 1 DBPR because the costs for

implementing the rule would exceed the potential benefits for these

systems.

    EPA understands commenters' concerns with the potential significant

economic burden on small systems. Because of this potential significant

impact, EPA has provided several requirements which will reduce the

burden on these systems. These requirements which are discussed above

and also in greater detail in the RIA (EPA, 1998g) include: (1) less

routine monitoring; and (2) extended compliance dates. EPA also

believes small systems can reduce their economic burden by; (1)

consolidation with larger systems; (2) using money from the State

revolving fund loans; and (3) using variances and exemptions when

needed. EPA considered an option in the development of the final rule

for large systems to have MCLs of 80 ug/L for TTHMs and 60 ug/L for

HAAs and for small systems to have a simple TTHM standard of 100 ug/L.

This option was rejected because allowing small systems to comply with

a different MCL level would not adequately protect the health of the

population served by these systems. EPA did not consider excluding

small systems from the Stage 1 DBPR, because these systems do not

currently have any standards for DBPs and the Agency believed there was

a public health concern that needed to be addressed. For a more

detailed description of the alternatives considered in the development

of the final rule see the final RIA (EPA, 1998g) or the final Unfunded

Mandates Reform Act Analysis for the Stage 1 DBPR (EPA, 1998o).



B. Paperwork Reduction Act



    The Office of Management and Budget (OMB) has approved the

information collection requirements contained in this rule under the

provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. and

has assigned OMB control number 2040-0204.

    The information collected as a result of this rule will allow the

States and the EPA to evaluate PWS compliance with the rule. For the

first three years after promulgation of the Stage 1 DBPR, the major

information requirements pertain to preparation for monitoring

activities, and for compliance tracking. Responses to the request for

information are mandatory (Part 141). The information collected is not

confidential.

    EPA is required to estimate the burden on PWS for complying with

the final rule. Burden means the total time, effort, or financial

resources expended by persons to generate, maintain, retain, or

disclose or provide information to or for a Federal agency. This

includes the time needed to review instructions; develop, acquire,

install, and utilize technology and systems for the purposes of

collecting, validating, and verifying information, processing and

maintaining information, and disclosing and providing information;

adjust the existing ways to comply with any previously applicable

instructions and requirements; train personnel to be able to respond to

a collection of information; search data sources; complete and review

the collection of information; and transmit or otherwise disclose the

information.

    EPA estimates that the annual burden on PWS and States for

reporting and recordkeeping will be 314,471 hours. This is based on an

estimate that there will be 4,631 respondents on average per year who

will need to provide about 9,449 responses and that the average

response will take 33 hours. The annual labor cost is estimated to be

about $12 million. In the first 3 years after promulgation of the rule,

only labor costs are incurred. The costs are incurred for the following

activities: reading and understanding the rule; planning; and training.

    An Agency may not conduct or sponsor, and a person is not required

to respond to a collection of information unless it displays a

currently valid OMB control number. The OMB control numbers for EPA's

regulations are listed in 40 CFR Part 9 and 48 CFR Chapter 15. EPA is

amending the table in 40 CFR Part 9 of currently approved ICR control

numbers issued by OMB for various regulations to list the information

requirements contained in this final rule. This ICR was previously

subject to public notice and comment prior to OMB approval. As a

result, EPA finds that there is ``good cause'' under section 553 (b)(B)

of the Administrative Procedures Act (5 U.S.C. 553 (b) (B)) to amend

this table without prior notice and comment. Due to the technical

nature of the table, further notice and comment would be unnecessary.



C. Unfunded Mandates Reform Act



1. Summary of UMRA Requirements

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public

Law 104-4, establishes requirements for Federal agencies to assess the

effects of their regulatory actions on State, local, and tribal

governments and the private sector. Under UMRA section 202, EPA

generally must prepare a written statement, including a cost-benefit

analysis, for proposed and final rules with ``Federal mandates'' that

may result in expenditures to State, local, and tribal governments, in

the aggregate, or to the private sector, of $100 million or more in any

one year. Before promulgating an EPA rule, for which a written

statement is needed, section 205 of the UMRA generally requires EPA to

identify and consider a reasonable number of regulatory alternatives

and adopt the least costly, most cost-effective or least burdensome

alternative that achieves the objectives of the rule. The provisions of

section 205 do not apply when they are inconsistent with applicable

law. Moreover, section 205 allows EPA to adopt an alternative other

than the least costly, most cost effective or least burdensome

alternative if the Administrator publishes with the final



[[Page 69454]]



rule an explanation on why that alternative was not adopted.

    Before EPA establishes any regulatory requirements that may

significantly or uniquely affect small governments, including tribal

governments, it must have developed, under section 203 of the UMRA, a

small government agency plan. The plan must provide for notification to

potentially affected small governments, enabling officials of affected

small governments to have meaningful and timely input in the

development of EPA regulatory proposals with significant Federal

intergovernmental mandates; and informing, educating, and advising

small governments on compliance with the regulatory requirements.

2. Written Statement for Rules With Federal Mandates of $100 Million or

More

    EPA has determined that this rule contains a Federal mandate that

may result in expenditures of $100 million or more for State, local,

and tribal governments, in the aggregate, and the private sector in any

one year. Accordingly, EPA has prepared, under section 202 of the UMRA,

a written statement addressing the following areas: (1) authorizing

legislation; (2) cost-benefit analysis including an analysis of the

extent to which the costs to State, local and Tribal governments will

be paid for by the federal government; (3) estimates of future

compliance costs and disproportionate budgetary effects; (4) macro-

economic effects; and (5) a summary of EPA's consultation with State,

local, and Tribal governments, and a summary of their concerns, and a

summary of EPA's evaluation of their concerns. A more detailed

description of this analysis is presented in EPA's Unfunded Mandates

Reform Act Analysis for the Stage 1 DBP Rule (EPA, 1998o) which is

included in the docket for this rule.

    a. Authorizing Legislation. Today's rule is promulgated pursuant to

Section 1412(b)(2) of the 1996 amendments to the SDWA; paragraph C of

this section establishes a statutory deadline of November 1998 to

promulgate this rule. This rule supersedes the TTHM Rule (EPA, 1979).

In addition, the Stage 1 DBP rule is closely integrated with the

IESWTR, which also has a statutory deadline of November 1998.

    b. Cost Benefit Analysis. Section IV discusses the cost and

benefits associated with the Stage 1 DBP rule. Also, the EPA's

Regulatory Impact Analysis of the Stage 1 Disinfectants/Disinfection

Byproducts Rule (EPA, 1998g) contains a detailed cost benefit analysis.

Today's rule is expected to have a total annualized cost of

approximately $701 million using a 7 percent cost of capital. The

analysis includes both qualitative and monetized benefits for

improvements to health and safety. Because of scientific uncertainty

regarding the exposure assessment and the risk assessment for DBPs, the

Agency has used five analytical approaches to assess the benefits of

the Stage 1 DBP. These analyses were based on the quantification of

bladder cancer health damages avoided. However, this rule may also

reduce colon and rectal cancers, as well as decrease adverse

reproductive and developmental effects. This would further increase the

benefits of this rule.

    Various Federal programs exist to provide financial assistance to

State, local, and Tribal governments in complying with this rule. The

Federal government provides funding to States that have primary

enforcement responsibility for their drinking water programs through

the Public Water Systems Supervision Grants program. Additional funding

is available from other programs administered either by EPA or other

Federal agencies. These include the Drinking Water State Revolving Fund

(DWSRF) and Housing and Urban Development's Community Development Block

Grant Program. For example, SDWA authorizes the Administrator of the

EPA to award capitalization grants to States, which in turn can provide

low cost loans and other types of assistance to eligible public water

systems. The DWSRF assists public water systems with financing the

costs of infrastructure needed to achieve or maintain compliance with

SDWA requirements. Each State will have considerable flexibility to

determine the design of its program and to direct funding toward its

most pressing compliance and public health protection needs. States may

also, on a matching basis, use up to ten percent of their DWSRF

allotments for each fiscal year to assist in running the State drinking

water program.

    c. Estimates of Future Compliance Costs and Disproportionate

Budgetary Effects. To meet the UMRA requirement in section 202, EPA

analyzed future compliance costs and possible disproportionate

budgetary effects. The Agency believes that the cost estimates,

indicated above and discussed in more detail in Section IV of this

rule, accurately characterize future compliance costs of the rule.

    In regard to the disproportionate impacts, EPA considered available

data sources in analyzing the disproportionate impacts upon geographic

or social segments of the nation or industry. This analysis was

difficult because impacts will most likely depend on a system's source

water characteristics and this data is not available for all systems.

However, it should be noted that the rule uniformly protects the health

of all drinking water system users regardless of the size or type of

system. Further analysis revealed that no geographic or social segment

patterns were likely for this rule. One observation is that the

historical pattern of development in this country led most large cities

to be developed near rivers and other bodies of water useful for power,

transportation, and drinking water. To the extent that this rule

affects surface water, it in most ways reflects the distribution of

population and geography of the nation. No rationale for

disproportionate impacts by geography or social segment was identified.

This analysis, therefore, developed three other measures: reviewing the

impacts on small systems versus large systems; reviewing the costs to

public versus private water systems; and reviewing the household costs

of the final rule.

    First, the national impacts on small systems (those serving fewer

than 10,000 people) versus large systems (those serving 10,000 people

or more) is indicated in Table V-1. The higher cost to the small ground

water systems is mostly attributable to the large number of these types

of systems (i.e. there are 68,171 small ground water systems, 1,320

large ground water systems, 5,165 small surface water systems, and

1,395 large surface water surface water systems).



                    Table V-1.--Annual Cost of Compliance for Small and Large Systems ($000)<SUP>*

----------------------------------------------------------------------------------------------------------------

                                                                               Small systems     Large systems

                                                                               (population <   (population <gr-

                                                                                  10,000)       thn-eq> 10,000)

----------------------------------------------------------------------------------------------------------------

Surface Water Systems (All).................................................         $56,804          $278,321



[[Page 69455]]





Ground Water System (All)...................................................         218,062           130,651

                                                                             -----------------------------------

    Total...................................................................         274,866           408,972

----------------------------------------------------------------------------------------------------------------

<SUP>* Costs calculated at a 7 percent cost of capital and include one time start-up costs.



    The second measure of disproportionate impact evaluated is the

relative total costs to public versus private water systems, by size.

EPA believes the implementation of the rule affects both public and

private water systems equally, with the variance in total cost by

system size merely a function of the number of affected systems.

    The third measure, household costs, can also be used to gauge the

impact of a regulation and to determine whether there are

disproportionately high impacts in particular segments of the

population. A detailed analysis of household cost impacts by system

size and system type are presented in Section IV.E. In summary, for

large surface water systems EPA estimates that 98 percent of households

will incur costs of less than $1 per month while 0.3 percent of

households will incur costs greater than $10 per month. For large

groundwater systems, EPA estimates that 95 percent of households will

incur costs of less than $1 per month while 1.0 percent of households

will incur costs greater than $10 per month. For small surface water

systems EPA estimates the 71 percent of households will incur costs of

less than $1 per month while 1 percent of households will incur costs

of greater than $10 per month. For small groundwater systems EPA

estimates that 91 percent of households will incur costs of less than

$1 per month while 4 percent of households will incur costs of greater

than $10 per month.

    The household analysis tends to overestimate the costs per

household because of the structure and assumptions of the methodology.

For example, the highest per-household cost would be incurred in a

system using membrane technology. These systems, conversely, might seek

less costly alternatives such as point-of-use devices, selection of

alternative water sources, or connecting into a larger regional water

system. The overall effect is that costs are higher in smaller systems,

and a higher percentage of those systems are publicly owned. Smaller

systems, however, represent a larger portion of systems that are not in

compliance with existing regulations. EPA believes that smaller systems

incurring the highest household costs may also incur the highest

reduction in risk. This is because smaller systems have not had to

previously comply with a TTHMs standard of 100 ug/L. In the RIA, EPA

estimates that on average, small systems will achieve about twice as

much reduction in risk as achieved by larger systems (EPA,1998g).

    Based on the analysis above, EPA does not believe there will be

disproportionate impacts on small systems, public versus private

systems, or generally by household. A more detailed description of this

analysis is presented in the EPA's Unfunded Mandates Reform Act

Analysis for the Stage 1 DBP Rule (EPA,1998o).

    d. Macro-economic Effects. As required under UMRA Section 202, EPA

is required to estimate the potential macro-economic effects of the

regulation. Macro-economic effects tend to be measurable in nationwide

econometric models only if the economic impact of the regulation

reaches 0.25 percent to 0.5 percent of Gross Domestic Product (GDP). In

1997, real GDP was $7,188 billion so a rule would have to cost at least

$18 billion to have a measurable effect. A regulation with a smaller

aggregate effect is unlikely to have any measurable impact unless it is

highly focused on a particular geographic region or economic sector.

The macro-economic effects on the national economy from the Stage 1

DBPR should be negligible based on the fact that the total annual costs

are about $701 million per year (at a 7 percent cost of capital) and

the costs are not expected to be highly focused on a particular

geographic region or sector.

    e. Summary of EPA's Consultation with State, Local, and Tribal

Governments and Their Concerns. Under UMRA section 202, EPA is to

provide a summary of its consultation with elected representatives (or

their designated authorized employees) of affected State, local and

Tribal governments in this rulemaking. Although this rule was proposed

before UMRA became a statutory requirement, EPA initiated consultations

with governmental entities and the private sector affected by this rule

through various means. This included participation on a Regulatory

Negotiation Committee chartered under the Federal Advisory Committee

Act (FACA) in 1992-93 that included stakeholders representing State and

local governments, public health organizations, public water systems,

elected officials, consumer groups, and environmental groups.

    After the amendments to SDWA in 1996, the Agency initiated a second

FACA process, similarly involving a broad range of stakeholders, and

held meetings during 1997 to address the expedited deadline for

promulgation of the Stage 1 DBPR in November 1998. EPA established the

M-DBP Advisory Committee to collect, share, and analyze new data

reviewed since the earlier Reg. Neg. process and also to build a

consensus on the regulatory implications of this new information. The

M-DBP Advisory Committee established a technical working group to

assist them with the many scientific issues surrounding this rule. The

Committee included representatives from organizations such as the

National League of Cities, the National Association of City and County

Health Officials, the Association of Metropolitan Water Agencies, the

Association of State Drinking Water Administrators, and the National

Association of Water Companies. In addition, the Agency invited the

Native American Water Association to participate in the FACA process to

develop this rule. Although they eventually decided not to take part,

the Association continued to be informed of meetings and developments

through a stakeholders mailing list.

    Stakeholders who participated in the FACA processes, as well as all

other interested members of the public, were invited to comment on the

proposed rule and NODAs. Also, as part of the Agency's Communication

Strategy, EPA sent copies of the proposed rule and NODAs to many

stakeholders, including six tribal associations.

    In addition, the Agency notified governmental entities and the

private



[[Page 69456]]



sector of opportunities to provide input on this Stage 1 DBPR in the

Federal Register on July 29, 1994 (59 FR 38668--EPA, 1994A), November

3, 1997 (62 FR 59485--EPA, 1997b), and on March 31, 1998 (63 FR 15974--

EPA, 1998a). Additionally, EPA extended the comment period for the

March 31, 1998 NODA and announced a public meeting to address new

information. EPA received approximately 213 written comments on the

July 29, 1994 notice, approximately 57 written comments on the November

3, 1997 notice, and approximately 41 written comments on the March 31,

1998 notice. Of the 213 comments received concerning the 1994 proposed

rule, 11% were from States and 41% were from local governments. Also,

one comment on the 1994 proposal was from a tribal group that

represented 43 tribes. Of the 57 comments received concerning the 1997

Notice of Data Availability, 18% were from States and 37% were from

local governments. Of the 41 comments received on the 1998 Notice of

Data Availability prior to the close of the comment period, 5% were

from States and 15% were from local governments.

    The public docket for this rulemaking contains all comments

received by the Agency and provides details about the nature of State,

local, and tribal government's concerns. State and local governments

raised several concerns including: the need for the Stage 1 DBPR; the

high costs of the rule in relation to the uncertain benefits; the

belief that not allowing predisinfection credit would increase the

microbial risk; and the need for flexibility in implementing the Stage

1 DPBR and IESWTR to insure the rules are implemented simultaneously.

The one tribal comment noted that compliance would come at a cost of

diverting funds away from other important drinking water needs such as

maintaining drinking water infrastructure.

    EPA understands the State, local, and tribal governments concerns

with the costs of the rule and the need to provide additional public

health protection for the expenditure. The Agency believes the final

Stage 1 DPBR will provide public health benefits to individuals by

reducing their exposures to DBPs, while not requiring excessive capital

expenditures. As discussed above, the majority of households will incur

additional costs of less than $1 per month. As discussed in section

III.E, the final rule maintains the existing predisinfection credit.

Finally, in the 1997 DBP NODA (EPA, 1997b), EPA requested comment on

four alternative schedules for complying with the Stage 1 DBPR. Most

State and local commenters preferred the option which provides the

maximum flexibility allowed under the SDWA for systems to comply with

the Stage 1 DBPR, and this is the option EPA selected for the final

rule.

    f. Regulatory Alternatives Considered. As required under Section

205 of the UMRA, EPA considered several regulatory alternatives

developed by the Reg Neg Committee and M-DBP Advisory Committee and

suggested by stakeholders.

    The Reg Neg Committee considered several options including a

proposed TTHMs MCL of 80 <greek-m>g/L and HAA5 MCL of 60 <greek-m>g/L

for large systems (and a simple standard of 100 <greek-m>g/l for small

systems). Another option called for the use of precursor removal

technology to reduce the level of total organic carbon with alternative

levels ranging from 4.0 to 0.5. Other options evaluated included a 80

<greek-m>g/L for TTHMs, 60 <greek-m>g/L for HAA5, and 4.0 for TOC.

Finally, an option was evaluated of a 80 <greek-m>g/L for TTHMs, 60

<greek-m>g/L for HAA5, and 5.0 for TOC. The final consensus included a

combination of MCLs which would be equal for all system size categories

and a target TOC level. Allowing small systems to comply with a

different MCL levels was rejected because the rule would not adequately

protect the health of the population served by these systems. A more

detailed description of these alternatives is discussed in the document

Unfunded Mandates Reform Act Analysis for the Stage 1 DBPR Rule which

can be found in the docket (EPA, 1998o).

    Other regulatory alternatives were considered by the M-DBP Advisory

Committee and these alternatives had the overall effect of reducing the

cost of the final rule. For example, the M-DBP Advisory Committee

recommended maintaining the predisinfection credit after reviewing data

which suggested that many systems could probably meet the proposed MCLs

for DBPs while maintaining current disinfection practices. This

decision was important because systems would have had to incur large

capital costs to remain in compliance with disinfection requirements if

predisinfection credits were disallowed. Thus by allowing

predisinfection, the overall cost of the rule was lowered.

    Also, the Committee recommended exempting systems for the enhanced

coagulation requirements based on their raw water quality. For example,

systems with raw-water TOC of less than or equal to 2.0 mg/L and raw-

water SUVA of less than or equal to 2.0 L/mg-m would be exempt from the

enhanced coagulation requirements. This exclusion was intended to

promote cost-effective enhanced coagulation (i.e., obtaining

efficiencies of TOC removal without excessive sludge production and

associated costs).

    In conclusion, EPA believes that the alternative selected for the

Stage 1 DBPR is the most cost-effective option that achieves the

objectives of the rule. For a complete discussion of this issue see

EPA's Regulatory Impact Analysis of the Stage 1 Disinfectants/

Disinfection Byproducts Rule (EPA,1998g).

3. Impacts on Small Governments

    The 1994 Stage 1 DBPR proposal was done without the benefit of the

UMRA requirements. However, in preparation for the final rule, EPA

conducted analysis on small government impacts and included small

government officials or their designated representatives in the rule

making process. The FACA processes gave a variety of stakeholders,

including small governments, the opportunity for timely and meaningful

participation in the regulatory development process. Representatives of

small government organizations were on both the Reg. Neg. Committee and

the M-DBP Advisory Committee and their representatives attended public

stakeholder meetings. Groups such as the National Association of City

and County Health Officials and the National League of Cities

participated in the rulemaking process. Through such participation and

exchange, EPA notified potentially affected small governments of

requirements under consideration and provided officials of affected

small governments with an opportunity to have meaningful and timely

input into the development of regulatory proposals.

    In addition, EPA will educate, inform, and advise small systems

including those run by small government about DBPR requirements. One of

the most important components of this process is the Small Entity

Compliance Guide, as required by the Small Business Regulatory

Enforcement Fairness Act of 1996. This plain-English guide will explain

what actions a small entity must take to comply with the rule. Also,

the Agency is developing fact sheets that concisely describe various

aspects and requirements of the DBPR.



D. National Technology Transfer and Advancement Act



    Under section 12(d) of the National Technology Transfer and

Advancement Act (NTTAA), the Agency is required to use voluntary

consensus standards in its regulatory activities unless to do so would

be inconsistent with applicable law or otherwise impractical. Voluntary

consensus standards are technical



[[Page 69457]]



standards (e.g., materials specifications, test methods, sampling

procedures, business practices, etc.) that are developed or adopted by

voluntary consensus standards bodies. Where available and potentially

applicable voluntary consensus standards are not used by EPA, the Act

requires the Agency to provide Congress, through OMB, an explanation of

the reasons for not using such standards.

    EPA's process for selecting the analytical test methods is

consistent with section 12(d) of the NTTAA. EPA performed literature

searches to identify analytical methods from industry, academia,

voluntary consensus standards bodies, and other parties that could be

used to measure disinfectants, DBPs, and other parameters. In addition,

EPA's selection of the methods benefited from the recommendations of an

Advisory Committee established under the FACA Act to assist the Agency

with the Stage 1 DBPR. The Committee made available additional

technical experts who were well-versed in both existing analytical

methods and new developments in the field.

    The results of these efforts form the basis for the analytical

methods in today's rule which includes: eight methods for measuring

different DBPs, of which five are EPA methods and three are voluntary

consensus standards; nine methods for measuring disinfectants, all of

which are voluntary consensus standards; three voluntary consensus

methods for measuring TOC; two EPA methods for measuring bromide; one

voluntary consensus method for measuring UV<INF>254</INF>, and both

governmental and voluntary consensus methods for measuring alkalinity.

Where applicable voluntary consensus standards were not approved, this

was due to their inability to meet the data quality objectives (e.g.

accuracy, sensitivity, quality control procedures) necessary for

demonstration of compliance with the relevant requirement.

    In the 1997 NODA, EPA requested comment on voluntary consensus

standards that had not been addressed and which should be considered

for addition to the list of approved analytical methods in the final

rule. No additional consensus methods were suggested by commenters.



E. Executive Order 12866: Regulatory Planning and Review



    Under Executive Order 12866, (58 FR 41344--EPA, 1993c) the Agency

must determine whether the regulatory action is ``significant'' and

therefore subject to OMB review and the requirements of the Executive

Order. The Order defines ``significant regulatory action'' as one that

is likely to result in a rule that may:

    1. Have an annual effect on the economy of $100 million or more or

adversely affect in a material way the economy, a sector of the

economy, productivity, competition, jobs, the environment, public

health or safety, or State, local, or tribal governments or

communities;

    2. Create a serious inconsistency or otherwise interfere with an

action taken or planned by another agency;

    3. Materially alter the budgetary impact of entitlement, grants,

user fees, or loan programs or the rights and obligations of recipients

thereof; or

    4. Raise novel legal or policy issues arising out of legal

mandates, the President's priorities, or the principles set forth in

the Executive Order.

    Pursuant to the terms of Executive Order 12866, it has been

determined that this rule is a ``significant regulatory action''

because it will have an annual effect on the economy of $100 million or

more. As such, this action was submitted to OMB for review. Changes

made in response to OMB suggestions or recommendations are documented

in the public record.



F. Executive Order 12898: Environmental Justice



    Executive Order 12898 establishes a Federal policy for

incorporating environmental justice into Federal agency missions by

directing agencies to identify and address disproportionately high and

adverse human health or environmental effects of its programs,

policies, and activities on minority and low-income populations. The

Agency has considered environmental justice related issues concerning

the potential impacts of this action and has consulted with minority

and low-income stakeholders.

    Two aspects of today's rule comply with the Environmental Justice

Executive Order which requires the Agency to consider environmental

justice issues in the rulemaking and to consult with Environmental

Justice (EJ) stakeholders. They can be classified as follows: (1) the

overall nature of the rule, and (2) the convening of a stakeholder

meeting specifically to address environmental justice issues. The Stage

1 DBPR applies to community water systems and nontransient noncommunity

water systems that treat their water with a chemical disinfectant for

either primary or residual treatment. Consequently, the health

protection benefits this rule provides are equal across all income and

minority groups within these communities.

    Finally, as part of EPA's responsibilities to comply with E.O.

12898, the Agency held a stakeholder meeting on March 12, 1998 to

address various components of pending drinking water regulations; and

how they may impact sensitive sub-populations, minority populations,

and low-income populations. Topics discussed included treatment

techniques, costs and benefits, data quality, health effects, and the

regulatory process. Participants included national, state, tribal,

municipal, and individual stakeholders. EPA conducted the meetings by

video conference call between eleven cities. This meeting was a

continuation of stakeholder meetings that started in 1995 to obtain

input on the Agency's Drinking Water Programs. The major objectives for

the March 12, 1998 meeting were:

    <bullet> Solicit ideas from EJ stakeholders on known issues

concerning current drinking water regulatory efforts;

    <bullet> Identify key issues of concern to EJ stakeholders; and

    <bullet> Receive suggestions from EJ stakeholders concerning ways

to increase representation of EJ communities in OGWDW regulatory

efforts.

    In addition, EPA developed a plain-English guide specifically for

this meeting to assist stakeholders in understanding the multiple and

sometimes complex issues surrounding drinking water regulation.

    Overall, EPA believes this rule will equally protect the health of

all minority and low-income populations served by systems regulated

under this rule from exposure to DBPs.



G. Executive Order 13045: Protection of Children From Environmental

Health Risks and Safety Risks



    Executive Order 13045 applies to any rule initiated after April 21,

1997, or proposed after April 21, 1998, that (1) is determined to be

``economically significant'' as defined under E.O. 12866 and (2)

concerns an environmental health or safety risk that EPA has reason to

believe may have a disproportionate effect on children. If the

regulatory action meets both criteria, the Agency must evaluate the

environmental health or safety effects of the planned rule on children,

and explain why the planned regulation is preferable to other

potentially effective and reasonably feasible alternatives considered

by the Agency.

    The final Stage 1 DBPR is not subject to the Executive Order

because EPA published a notice of proposed rulemaking before April 21,

1998.



[[Page 69458]]



However, EPA's policy since November 1, 1995, is to consistently and

explicitly consider risks to infants and children in all risk

assessments generated during its decision making process including the

setting of standards to protect public health and the environment.

    EPA's Office of Water has historically considered risks to

sensitive populations (including fetuses, infants, and children) in

establishing drinking water assessments, advisories or other guidance,

and standards (EPA, 1989c and EPA, 1991). The disinfection of public

drinking water supplies to prevent waterborne disease is the most

successful public health program in U.S. history. However, numerous

chemical byproducts (DBPs) result from the reaction of chlorine and

other disinfectants with naturally occurring organic and inorganic

material in source water, and these may have potential health risks.

Thus, maximizing health protection for sensitive subpopulations

requires balancing risks to achieve the recognized benefits of

controlling waterborne pathogens while minimizing risk of potential DBP

toxicity. Human experience shows that waterborne disease from pathogens

in drinking water is a major concern for children and other subgroups

(elderly, immune compromised, pregnant women) because of their greater

vulnerabilities (Gerba et al., 1996). Based on animal studies, there is

also a concern for potential risks posed by DBPs to children and

pregnant women (EPA, 1994a; EPA, 1998a).

    In developing this regulation, risks to sensitive subpopulations

(including fetuses and children) were taken into account in the

assessments of disinfectants and disinfection byproducts. A description

of the data available for evaluating risks to children and the

conclusions drawn can be found in the public docket for this rulemaking

(EPA, 1998h). In addition, the Agency has evaluated alternative

regulatory options and selected the option that will provide the

greatest benefits for all people including children. See the regulatory

impact analysis for a complete discussion of the different options

considered. It should also be noted that the IESTWR, which accompanies

this final rule, provides better controls of pathogens and achieves the

goal of increasing the protection of children.



H. Consultations With the Science Advisory Board, National Drinking

Water Advisory Council, and the Secretary of Health and Human Services



    In accordance with section 1412 (d) and (e) of the Act, the Agency

submitted the proposed Stage 1 DBP rule to the Science Advisory Board,

National Drinking Water Advisory Council (NDWAC), and the Secretary of

Health and Human Services for their review. EPA has evaluated comments

received from these organizations and considered them in developing the

final Stage 1 DBP rule.



I. Executive Order 12875: Enhancing the Intergovernmental Partnership



    Under Executive Order 12875, EPA may not issue a regulation that is

not required by statute and that creates a mandate upon a State, local

or tribal government, unless the Federal government provides the funds

necessary to pay the direct compliance costs incurred by those

governments, or EPA consults with those governments. If EPA complies by

consulting, Executive Order 12875 requires EPA to provide to the Office

of Management and Budget a description of the extent of EPA's prior

consultation with representatives of affected State, local and tribal

governments, the nature of their concerns, copies of any written

communications from the governments, and a statement supporting the

need to issue the regulation. In addition, Executive Order 12875

requires EPA to develop an effective process permitting elected

officials and other representatives of State, local and tribal

governments ``to provide meaningful and timely input in the development

of regulatory proposals containing significant unfunded mandates.''

    EPA has concluded that this rule will create a mandate on State,

local, and tribal governments and that the Federal government will not

provide all of the funds necessary to pay the direct costs incurred by

the State, local, and tribal governments in complying with the mandate.

In developing this rule, EPA consulted with State and local governments

to enable them to provide meaningful and timely input in the

development of this rule. EPA also invited the Native American Water

Association to participate in the FACA process to develop this rule,

but they decided not to take part in the deliberations.

    As described in Section V.C.2.e, EPA held extensive meetings with a

variety of State and local representatives, who provided meaningful and

timely input in the development of the proposed rule. State and local

representatives were also part of the FACA committees involved in the

development of this rule. Summaries of the meetings have been included

in the public docket for this rulemaking. See section V.C.2.e for

summaries of the extent of EPA's consultation with State, local, and

tribal governments; the nature of the government concerns; and EPA's

position supporting the need to issue this rule.



J. Executive Order 13084: Consultation and Coordination With Indian

Tribal Governments



    Under Executive Order 13084, EPA may not issue a regulation that is

not required by statute, that significantly or uniquely affects the

communities of Indian tribal governments, and that imposes substantial

direct compliance costs on those communities, unless the Federal

government provides the funds necessary to pay the direct compliance

costs incurred by the tribal governments, or EPA consults with those

governments. If EPA complies by consulting, Executive Order 13084

requires EPA to provide to the Office of Management and Budget, in a

separately identified section of the preamble to the rule, a

description of the extent of EPA's prior consultation with

representatives of affected tribal governments, a summary of the nature

of their concerns, and a statement supporting the need to issue the

regulation. In addition, Executive Order 13084 requires EPA to develop

an effective process permitting elected officials and other

representatives of Indian tribal governments ``to provide meaningful

and timely input in the development of regulatory policies on matters

that significantly or uniquely affect their communities.''

    EPA has concluded that this rule will significantly affect

communities of Indian tribal governments. It will also impose

substantial direct compliance costs on such communities, and the

Federal government will not provide all the funds necessary to pay the

direct costs incurred by the tribal governments in complying with the

rule. In developing this rule, EPA consulted with representatives of

tribal governments pursuant to both Executive Order 12875 and Executive

Order 13084. EPA's consultation, the nature of the governments'

concerns, and EPA's position supporting the need for this rule are

discussed above in the preamble section that addresses compliance with

Executive Order 12875. Specifically in developing this rule, the Agency

invited the Native American Water Association to participate in the

FACA process to develop this rule. Although they eventually decided not

to take part, the Association continued to be informed of meetings and

developments through a stakeholders mailing list. As described in

Section V.C.2.e of the discussion on



[[Page 69459]]



UMRA, EPA held extensive meetings that provided the opportunity for

meaningful and timely input in the development of the proposed rule.

Summaries of the meetings have been included in the public docket for

this rulemaking.



K. Submission to Congress and the General Accounting Office



    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the

Small Business Regulatory Enforcement Fairness Act of 1996, generally

provides that before a rule may take effect, the agency promulgating

the rule must submit a rule report, which includes a copy of the rule,

to each House of the Congress and to the Comptroller General of the

United States. EPA will submit a report containing this rule and other

required information to the U.S. Senate, the U.S. House of

Representatives, and the Comptroller General of the United States prior

to publication of the rule in the Federal Register. A major rule cannot

take effect until 60 days after it is published in the Federal

Register. This rule is a ``major rule'' as defined by 5 U.S.C. 804(2).

This rule will be effective February 16, 1999.



L. Likely Effect of Compliance With the Stage 1 DBPR on the Technical,

Financial, and Managerial Capacity of Public Water Systems



    Section 1420(d)(3) of the SDWA as amended requires that, in

promulgating a NPDWR, the Administrator shall include an analysis of

the likely effect of compliance with the regulation on the technical,

financial, and managerial capacity of public water systems. The

following analysis has been performed to fulfill this statutory

obligation.

    Overall water system capacity is defined in EPA guidance (EPA 816-

R-98-006) as the ability to plan for, achieve, and maintain compliance

with applicable drinking water standards. Capacity has three

components: technical, managerial, and financial.

    Technical capacity is the physical and operational ability of a

water system to meet SDWA requirements. Technical capacity refers to

the physical infrastructure of the water system, including the adequacy

of source water and the adequacy of treatment, storage, and

distribution infrastructure. It also refers to the ability of system

personnel to adequately operate and maintain the system and to

otherwise implement requisite technical knowledge. A water system's

technical capacity can be determined by examining key issues and

questions, including:

    <bullet> Source water adequacy. Does the system have a reliable

source of drinking water? Is the source of generally good quality and

adequately protected?

    <bullet> Infrastructure adequacy. Can the system provide water that

meets SDWA standards? What is the condition of its infrastructure,

including well(s) or source water intakes, treatment, storage, and

distribution? What is the infrastructure's life expectancy? Does the

system have a capital improvement plan?

    <bullet> Technical knowledge and implementation. Is the system's

operator certified? Does the operator have sufficient technical

knowledge of applicable standards? Can the operator effectively

implement this technical knowledge? Does the operator understand the

system's technical and operational characteristics? Does the system

have an effective operation and maintenance program?

    Managerial capacity is the ability of a water system to conduct its

affairs in a manner enabling the system to achieve and maintain

compliance with SDWA requirements. Managerial capacity refers to the

system's institutional and administrative capabilities.

Managerial capacity can be assessed through key issues and questions,

including:

    <bullet> Ownership accountability. Are the system owner(s) clearly

identified? Can they be held accountable for the system?

    <bullet> Staffing and organization. Are the system operator(s) and

manager(s) clearly identified? Is the system properly organized and

staffed? Do personnel understand the management aspects of regulatory

requirements and system operations? Do they have adequate expertise to

manage water system operations? Do personnel have the necessary

licenses and certifications?

    <bullet> Effective external linkages. Does the system interact well

with customers, regulators, and other entities? Is the system aware of

available external resources, such as technical and financial

assistance?

    Financial capacity is a water system's ability to acquire and

manage sufficient financial resources to allow the system to achieve

and maintain compliance with SDWA requirements.

    Financial capacity can be assessed through key issues and

questions, including:

    <bullet> Revenue sufficiency. Do revenues cover costs? Are water

rates and charges adequate to cover the cost of water?

    <bullet> Credit worthiness. Is the system financially healthy? Does

it have access to capital through public or private sources?

    <bullet> Fiscal management and controls. Are adequate books and

records maintained? Are appropriate budgeting, accounting, and

financial planning methods used? Does the system manage its revenues

effectively?

    There are 76,051 systems affected by this rule. Of these, 12,998

will have to modify their treatment process and undertake disinfectant

and DBP monitoring and reporting. Some of this smaller group may also

be required to do DBP precursor monitoring and reporting. The other

63,063 systems will need to do disinfectant and DBP monitoring and

reporting, but will not need to modify their treatment process. Some of

this larger group may also be required to do DBP precursor monitoring

and reporting.

    Systems not modifying treatment are not generally expected to

require significantly increased technical, financial, or managerial

capacity to comply with these new requirements. Certainly some

individual facilities may have weaknesses in one or more of these areas

but overall, systems should have or be able to obtain the capacity

needed for these activities.

    Systems needing to modify treatment will employ one or more of a

variety of steps. The steps expected to be employed by 50% or more of

subpart H systems and by eight percent or more of ground water systems

covered by the rule include a combination of low cost alternatives,

including switching to chloramines for residual disinfection, moving

the point of disinfectant application, and improving precursor removal.

EPA estimates that less than seven percent of systems in any category

will resort to higher cost alternatives, such as switching to ozone or

chloramines for primary disinfection or using GAC or membranes for

precursor removal. These higher cost alternatives may also provide

other treatment benefits, so the cost may be somewhat offset by

eliminating the need for technologies to remove other contaminants.

Some of these systems may choose nontreatment alternatives such as

consolidation with another system or changing to a higher quality water

source.

    Furthermore, there are a number of actions that are expected to be

taken disproportionately by smaller sized systems (that is to say, a

greater percentage of smaller sized systems will undertake than will

larger sized systems). These steps include increased plant staffing and

additional staff training to understand process control strategy. Small

systems will be required to do this since larger systems have already

undertaken these changes to



[[Page 69460]]



some extent for compliance with the 1979 TTHM rule.

    For many systems serving less than 10,000 persons which need to

make treatment modifications, an enhancement of technical, financial,

and managerial capacity may likely be needed. As the preceding

paragraph makes clear, these systems will be making structural

improvements and enhancing laboratory and staff capacity. Larger sized

systems have typically already made these improvements as part of

normal operations. Meeting the requirements of the Stage 1 DBPR will

require operating at a higher level of sophistication and in a better

state of repair than some plants serving less than 10,000 people have

considered acceptable in the past.

    Certainly there will be exceptions in systems serving both below

10,000 persons and above. Some larger plants will doubtless find their

technical, managerial, and financial capacity taxed by the new

requirements. Likewise, some plants serving less than 10,000 persons

will already have more than adequate technical, financial, and

managerial capacity to meet these requirements. However, in general,

the systems serving less than 10,000 persons needing to make treatment

modifications will be the ones most needing to enhance their capacity.



VI. References



1. APHA. 1992. Standard Methods for the Examination of Water and

Wastewater, 18th Edition. American Public Health Association,

Washington, DC.

2. APHA. 1995. Standard Methods for the Examination of Water and

Wastewater, 19th Edition. American Public Health Association,

Washington DC.

3. APHA. 1996. Standard Methods for the Examination of Water and

Wastewater, 19th Edition, Supplement. American Public Health

Association, Washington DC.

4. ASTM. 1993. Methods D-1067-88B, D-2035-80. Annual Book of ASTM

Standards. Vol. 11.01, American Society for Testing and Materials.

5. ASTM. 1994. Methods D-1067-92B. Annual Book of ASTM Standards.

Vol. 11.01, American Society for Testing and Materials.

6. ASTM. 1996. Methods D-1253-86. Annual Book of ASTM Standards.

Vol. 11.01, American Society for Testing and Materials.

7. Bove, F.J., et al. 1995. Public Drinking Water Contamination and

Birth Outcomes. Amer. J. Epidemiol., 141(9), 850-862.

8. Bull, R.J. and Kopfler, F.C. 1991. Health Effects of

Disinfectants and Disinfection Byproducts. Prepared for the American

Water Works Research Foundation.

9. Cantor K. P., Hoover R., Hartge P., et al. 1985. Drinking Water

Source and Bladder Cancer: A Case-Control Study. In Jolley R.L.,

Bull R.J., Davis W.P., et al. (eds), Water Chlorination: Chemistry,

Environmental Impact and Health Effects, Vol. 5. Lewis Publishers,

Inc., Chelsea, MI pp 145-152.

10. Cantor K.P., Hoover R., Hartge P. et al. 1987. Bladder Cancer,

Drinking Water Source and Tap Water Consumption: A Case Control

Study. JNCI; 79:1269-79.

11. Cantor K.P., Lunch C.F., Hildesheim M., Dosemeci M., Lubin J.,

Alavanja M., Craun G.F.. 1998. Drinking Water Source and

Chlorination Byproducts. I. Risk of Bladder Cancer. Epidemiology;

9:21-28.

12. Chowdhury, Z. 1997. Presentation to Technical Work Group

January, 1997. Cincinnati, OH.

13. Clark, S.C., J. Wiginton, and J.T. Musgrove. 1994. Enhanced Lime

Softening: Is Your TOC Removal Maxed Out? AWWA Enhanced Coagulation

Workshop, December 1994.

14. CMA. 1996. Sodium Chlorite: Drinking Water Rat Two-Generation

Reproductive Toxicity Study. Chemical Manufacturers Association.

Quintiles Report Ref. CMA/17/96.

15. CMA. 1998. Letter to Michael Cox, U.S. EPA, OGWDW. From Marian

K. Stanley, Chemical Manufacturers Association. Regarding the two-

generation reproduction/developmental neurotoxicity study with

sodium chlorite. January 26, 1998. 20 pp.

16. DeAngelo, A. B., Daniel, F. B., Most, B. M. and G. R. Olsen.

1997. The Failure of Monochloroacetic Acid and Trichloroacetic Acid

Administered in the Drinking Water to Produce Liver Cancer in Male

F344/N rats. J. Toxicol. Environ. Health (in press).

17. DeAngelo A. B., George M. H., Kilburn S. R., Moore T. M., Wolf

D. C. 1998. Carcinogenicity of Potassium Bromate Administered in the

Drinking Water to Make B6C3F1 Mice and F344/N Rats, Toxicologic

Pathology vol.26, No.4 (in press).

18. Doyle T. J., Sheng W., Cerhan J. R., Hong C. P., Sellers T. A.,

Kushi, L. H., Folsom A. R. 1997. The Association of Drinking Water

Source and Chlorination By-products with Cancer Incidence Among

Postmenopausal Women in Iowa: A Prospective Cohort Study. American

Journal of Public Health. 87:7.

19. Edwards, M. 1997. Predicting DOC Removal During Enhanced

Coagulation. Jour. AWWA (89:5:78).

20. Edzwald, J. K., and J. E. Van Benschoten. 1990. Aluminum

Coagulation of Natural Organic Matter. Proc. Fourth Int'l Gothenburg

Symposium on Chemical Treatment, Madrid, Spain (Oct. 1990).

21. Federal Focus. 1996. Principles for Evaluating Epidemiological

Data in Regulatory Risk Assessment. Developed By An Expert Panel at

a Conference in London, England October 1995. Appendix B: The

``Bradford Hill'' or ``Surgeon General's'' Criteria for Judging the

Causal Significance of an Exposure-Effect Association Indicated by

an Epidemiological Study or Studies. August 1996. Federal Focus,

Inc. Washington, DC.

22. Freedman M., Cantor K. P., Lee N. L., Chen L. S., Lei H. H.,

Ruhl C. E., and Wang S. S. 1997. Bladder cancer and drinking water:

a population-based case-control study in Washington County, Maryland

(United States). Cancer Causes and Control. 8, pp 738-744.

23. Gerba, CP., J.B Rose, and C.N Haas. 1996. Sensitive Populations:

Who is at the Greatest Risk. Int. J. Food and Microbiology. 30:113-

123.

24. Heywood R., Sortwell R.J., Noel PRB, Street AE, Prentice DE, Roe

FJC, Wadsworth PF, Worden AN, Van Abbe NJ. 1979. Safety Evaluation

of Toothpaste Containing Chloroform. III. Long-term Study in Beagle

Dogs. J. Environ. Pathol. Toxicol. 2:835-851.

25. Hildesheim M.E., Cantor K.P., Lynch C.F., Dosemeci M., Lubin J.,

Alavanja M., and Craun G.F. 1998. Drinking Water Source and

Chlorination Byproducts: Risk of Colon and Rectal Cancers.

Epidemiology. 9:1, pp: 29-35.

26. ILSI. 1997. An Evaluation of EPA's Proposed Guidelines for

Carcinogen Risk Assessment Using Chloroform and Dichloroacetate as

Case Studies: Report of an Expert Panel. International Life Sciences

Institute, Health and Environmental Sciences Institute November,

1997.

27. Jorgenson T.A., Meierhenry E.F., Rushbrook C.J. Bull RJ,

Robinson M. 1985. Carcinogenicity of Chloroform in Drinking Water to

Male Osborne-Mendel Rats and Female B6C3F<INF>1</INF> Mice. Fundam.

Appl. Toxicol. 5:760-769.

28. Kanitz, S. et al. 1996. Association Between Drinking Water

Disinfection and Somatic Parameters at Birth. Environ. Health

Perspectives, 104(5), 516-520.

29. Kaplan, L.A. 1992. Comparison of High Temperature and Persulfate

Oxidation Methods for Determination of Dissolved Organic Carbon in

Freshwaters. Limnol. Oceanogr. 37 (5): 1119-25.

30. King, W. D. and L. D. Marrett. 1996. Case-Control Study of Water

Source and Bladder Cancer. Cancer Causes and Control, 7:596-604.

31. Klotz, J. B. and Pyrch, L. A. 1998. A Case-Control Study of

Neural Tube Defects and Drinking Water Contaminants. New Jersey

Department of Health and Senior Services.

32. Krasner, Stuart. April 1997. Issue Paper on Enhanced Coagulation

to the M-DBP Advisory Committee.



[[Page 69461]]



33. Kurokawa et al. 1986a. Dose-response Studies on the

Carcinogenicity of Potassium Bromate in F344 Rats after Long-term

Oral Administration. J. Natl. Cancer Inst. 77:977-982.

34. Kurokawa et al. 1986b. Long-term in vitro Carcinogenicity Tests

of Potassium Bromate, Sodium Hypochlorite and Sodium Chlorite

Conducted in Japan. Environ. Health Perspect. 69:221-236.

35. McGeehin, M.A. et al. 1993. Case-Control Study of Bladder Cancer

and Water Disinfection Methods in Colorado. Am. J. Epidemiology,

138:492-501.

36. Mobley, S. A., D. H. Taylor, R. D. Laurie, and R. J. Pfohl.

1990. Chlorine dioxide depresses T3 uptake and delays development of

locomotor activity in young rats. In: Water Chlorination: Chemistry,

Environmental Impact and Health Effects. Vol 6. Lolley, Condie,

Johnson, Katz, Mattice and Jacobs, ed. lewis Publ., Inc. Chelsea

MI., pp 347-360.

37. Morris, R. D. et al. 1992. Chlorination, Chlorination By-

products, and Cancer: A Meta-Analysis. American Journal of Public

Health, 82(7): 955-963.

38. Moser, G. September 9, 1997. Letter to Yogi Patel, U.S. EPA, OW.

Regarding the Neurodevelopment Section of the CMA Study of Chlorite.

39. NTP. 1985. National Toxicology Program. Toxicology and

carcinogenesis studies of chlorodibromomethane in F344/N rats and

B6C3F<INF>1</INF> mice (gavage studies). Tech. Rep. Ser. No. 282.

40. NTP. 1987. National Toxicology Program. Toxicity and

carcinogenesis studies of bromodichloromethane in F344/N rats and

B6C3F<INF>1</INF> mice (gavage studies). Technical Report Series No.

321.

41. NTP. 1989. National Toxicology Program. Toxicology and

carcinogenesis studies of bromoform in F344/N rats and

B6C3F<INF>1</INF> mice (gavage studies). Tech. Rep. Ser. No. 350.

42. NTP. 1990. National Toxicology Program. NTP Technical Report on

the Toxicology and Carcinogenesis studies of chlorinated and

chloraminated water in F344/N rats and B6C3F<INF>1</INF> mice

(drinking water studies). NTP TR 392, National Institutes of Health,

474pp.

43. Orme, J. D.H. Taylor, R.D. Laurie, and R.J. Bull. 1985. Effects

of Chlorine Dioxide on Thyroid Function in Neonatal Rats. J. Tox.

and Environ. Health. 15:315-322.

44. OSTP. 1985. Chemical Carcinogens; A Review of the Science and

Its Associated Principles, February 1985. Presented in Risk

Analysis: A guide to Principles and Methods for Analyzing Health and

Environmental Risks. Appendix G. Federal Register, March 14, 1985.

Pages 10371-10442.

45. Owen, D. M.; Amy, G. L. and Z. K. Chowdhury. 1993.

Characterization of Natural Organic Matter and Its Relationship to

Treatability. AWWA Research Foundation & AWWA, Denver, CO.

46. Poole, C. 1997. Analytical Meta-Analysis of Epidemiological

Studies of Chlorinated Drinking Water and Cancer: Quantitative

Review and Reanalysis of the Work Published by Morris et al., Am J

Public Health 1992:82:955-963. National Center for Environmental

Assessment, Office of Research and Development, September 30, 1997.

47. Randtke, S. J.; Hoehn, R. C.; Knocke, W. R.; Dietrich, A. M.;

Long, B. W.; and N. A. Wang. 1994. Comprehensive Assessment of DBP

Precursor Removal by Enhanced Coagulation and Softening. Proc. AWWA

Ann. Conf. (Water Quality), New York, NY, pp. 737-777.

48. Reif, J. S. et al. 1996. Reproductive and Developmental Effects

of Disinfection By-products in Drinking Water. Environmental Health

Prospectives. 104(10):1056-1061.

49. Sanders, V.M., B.M. Kauffman, K.L. White, K.A. Douglas, D.W.

Barnes, L.E. Sain, T.J. Bradshaw, J.F. Borzelleca and A.E. Munson.

1982. Toxicology of chloral hydrate in the mouse. Environ. Health

Perspect. 44:137-146.

50. Savitz, D. A., Andrews, K. W. and L. M. Pastore. 1995. Drinking

Water and Pregnancy Outcome in Central North Carolina: Source,

Amount, and Trihalomethane levels. Environ. Health Perspectives.

103(6), 592-596.

51. Shorney, H. L., Randtke, S. J., Hargette, P. H., Mann, P. D.,

Hoehn, R.C., Knocke, W. R., Dietrich, A. M. and B. W. Long. 1996.

The Influence of Raw Water Quality on Enhanced Coagulation and

Softening for the Removal of NOM and DBP Formation Potential,

Proceedings 1996 AWWA Annual Conference, Toronto, Ontario, Canada.

52. Singer, P. C., Harrington, G. W., Thompson, J. D. and M. C.

White. 1995. Enhanced Coagulation and Enhanced Softening for the

Removal of Disinfection By-Product Precursors: An Evaluation. Report

prepared for the AWWA Government Affairs Office, Washington, DC, by

the Dept. of Environmental Sciences and Engineering, UNC, Chapel

Hill, NC.

53. Singer, P. C., Harrington, G. W., Thompson, J. and M. White.

1996. Enhanced Coagulation and Enhanced Softening for the Removal of

Disinfection By-Product Precursors: An Evaluation, Report to AWWA

Disinfectants/Disinfection By-Products Technical Advisory Workgroup

of the Water Utility Council, December 1996.

54. Smith, M.K., Randall, J.L., Read, E.J., and Stober, J.A. 1989.

Teratogenic activity of trichloroacetic acid in the rat. Teratology

40:445-451.

55. Summers, R.S., G. Solarik, V.A. Hatcher, R.S. Isabel, and J.F.

Stile. 1997. Analyzing the Impacts of Predisinfection Through Jar

Testing, Proceedings, AWWA Water Quality Technology Conference,

Denver, CO.

56. Tseng, T. and M. Edwards. 1997. Considerations in Optimizing

Coagulation. Proc. 1996 AWWA Water Qual. Technol. Conf., Boston,

Mass.

57. U.S. EPA. 1979. National Interim Primary Drinking Water

Regulations; Control of Trihalomethanes in Drinking Water. Fed.

Reg., 44:231:68624. (November 29, 1979)

58. U.S. EPA. 1983. EPA Method 310.1. Methods of Chemical Analysis

of Water and Wastes. Envir. Monitoring Systems Laboratory,

Cincinnati, OH. EPA 600/4-79-020. 460 pp.

59. U.S. EPA. 1986. Guidelines for Carcinogen Risk Assessment, Fed.

Reg. 51(185):33992-34003. EPA/600/8-87/045. NTIS PB88-123997.

60. U.S. EPA. 1987. Drinking Water Regulations; Public Notification;

Final Rule. Federal Register. Vol. 52, No. 208, Wednesday, Oct. 28,

1987--Part II. pp. 41534-41550.

61. U.S. EPA. 1988. EPA Method 502.2. Methods for the Determination

of Organic Compounds in Drinking Water. EPA 600/4-88-039. PB91-

231480. Revised July 1991.

62. U.S. EPA. 1989a. National Primary Drinking Water Regulations;

Filtration, Disinfection; Turbidity, Giardia lamblia, Viruses,

Legionella, and Heterotrophic Bacteria; Final Rule. Part II. Fed.

Reg., 54:124:27486. (June 29, 1989)

63. U.S. EPA 1989b. National Primary Drinking Water Regulations;

Total Coliforms (Including Fecal Coliform and E. Coli); Final Rule.

Fed. Reg., 54:124:27544. (June 29, 1989)

64. U.S. EPA. 1989c. Review of Environmental Contaminants and

Toxicology. USEPA. Office of Drinking Water Health Advisories,

Volume 106. 225pp.

65. U.S. EPA. 1990. EPA Methods 551, 552. Methods for the

Determination of Organic Compounds in Drinking Water--Supplement I.

EPA 600/4-90-020. PB91-146027.

66 U.S. EPA. 1991. National Primary Drinking Water Regulations:

Final Rule. Fed, reg., 56:20, January 30, 1991 3526-3597.

67. U.S. EPA. 1992. EPA Methods 524.2, 552.1. Methods for the

Determination of Organic Compounds in Drinking Water--Supplement II.

EPA 600/R-92/129. PB92-207703.

68. U.S. EPA. 1993a. Draft Drinking Water Health Criteria Document

for Bromate. Office of Science and Technology, Office of Water. Sep.

30, 1993.

69. U.S. EPA. 1993b. EPA Method 300.0. The Determination of

Inorganic Anions by Ion Chromatography in the Manual ``Methods for

the Determination of Inorganic Substances in Environmental

Samples,'' EPA/600/R/93/100. NTIS, PB94120821.

70. U.S. EPA. 1993c. Executive Order 12866: Regulatory Planning and

Review. Federal Register. Vol. 58, No. 190. October 4, 1993. 51735-

51744.

71. U.S. EPA/ILSI. 1993. A Review of Evidence on Reproductive and

Developmental Effects of Disinfection By-Products in Drinking Water.

Washington: U.S. Environmental Protection Agency and International

Life Sciences Institute.



[[Page 69462]]



72. U.S. EPA. 1994a. National Primary Drinking Water Regulations;

Disinfectants and Disinfection Byproducts; Proposed Rule. Fed. Reg.,

59:145:38668. (July 29, 1994).

73. U.S. EPA. 1994b. National Primary Drinking Water Regulations;

Enhanced Surface Water Treatment Requirements; Proposed Rule. Fed.

Reg., 59:145:38832. (July 29, 1994).

74. U.S. EPA. 1994c. National Primary Drinking Water Regulations;

Monitoring Requirements for Public Drinking Water Supplies; Proposed

Rule. Fed. Reg., 59:28:6332. (February 10, 1994).

75. U.S. EPA. 1994d. Final Draft Drinking Water Health Criteria

Document for Chlorine Dioxide, Chlorite and Chlorate. Office of

Science and Technology, Office of Water. March 31, 1994.

76. U.S. EPA. 1994e. Draft Drinking Water Health Criteria Document

for Chlorine, Hypochlorous Acid and Hypochlorite Ion. Office of

Science and Technology, Office of Water.

77. U.S. EPA. 1994f. Health and Ecological Criteria Div., OST. Final

Draft for the Drinking Water Criteria Document on Trihalomethanes.

Apr. 8. 1994.

78. U.S. EPA. 1994g. Draft Drinking Water Health Criteria Document

for Chlorinated Acetic Acids/Alcohols/Aldehydes and Ketones. Office

of Science and Technology, Office of Water.

79. U.S. EPA. 1994h. Draft Drinking Water Health Criteria Document

for Chloramines. Office of Science and Technology, Office of Water.

80. U.S. Environmental Protection Agency. 1994i. Regulatory Impact

Analysis of Proposed Disinfectant/Disinfection Byproduct

Regulations. Washington, DC. EPA-68-C3-0368.

81. U.S. EPA. 1995. Methods for the Determination of Organic

Compounds in Drinking Water. Supplement III. EPA-600/R-95/131. NTIS,

PB95261616.

82. U.S. EPA. 1996a. National Primary Drinking Water Regulations:

Monitoring Requirements for Public Drinking Water Supplies; Final

Rule. Fed. Reg., 61:94:24354. (May 14, 1996)

83. U.S. EPA. 1996b. Proposed Guidelines for Carcinogen Risk

Assessment. U.S. EPA, April 23, 1996.

84. U.S. EPA. 1997a. National Primary Drinking Water Regulations;

Interim Enhanced Surface Water Treatment Rule; Notice of Data

Availability; Proposed Rule. Fed. Reg., 62 (No. 212): 59486-59557.

(November 3, 1997).

85. U.S. EPA. 1997b. National Primary Drinking Water Regulations;

Disinfectants and Disinfection Byproducts; Notice of Data

Availability; Proposed Rule. Fed. Reg., 62 (No. 212): 59388-59484.

(November 3, 1997).

86. U.S. EPA. 1997c. Summaries of New Health Effects Data. Office of

Science and Technology, Office of Water. October 1997.

87. U.S. EPA. 1997d. External Peer Review of CMA Study -2-

Generation, EPA Contract No. 68-C7-0002, Work Assignment B-14, The

Cadmus Group, Inc., October 9, 1997.

88. U.S. EPA. 1997e. Method 300.1. Determination of Inorganic Anions

in Drinking Water by Ion Chromatography. Revision 1.0. USEPA

National Exposure Research Laboratory, Cincinnati OH.

89. U.S. EPA. 1997f. Performance Based Measurement System. Notice of

Intent. Federal Register, October 6, 1997. Vol. 62, No. 193., 52098-

52100.

90. U.S. EPA. 1997g. Manual for the Certification of Laboratories

Analyzing Drinking Water, Fourth Edition, Office of Water Resource

Center (RC-4100), EPA 815-B-97-001. March 1997.

91. U.S. EPA. 1998a. National Primary Drinking Water Regulations;

Disinfectants and Disinfection Byproducts; Notice of Data

Availability; Proposed Rule. Fed. Reg., 63 (No. 61): 15606-15692.

(March 31, 1998).

92. U.S. EPA. 1998b. Dichloroacetic acid: Carcinogenicity

Identification Characterization Summary. National Center for

Environmental Assessment--Washington Office. Office of Research and

Development. March 1998. EPA 815-B-98-010. PB 99-111387.

93. U.S. EPA. 1998c. Quantification of Bladder Cancer Risk from

Exposure to Chlorinated Surface Water. Office of Science and

Technology, Office of Water. November 9, 1998.

94. U.S. EPA. 1998d. Health Risk Assessment/Characterization of the

Drinking Water Disinfection Byproduct Chlorine Dioxide and the

Degradation Byproduct Chlorite. Office of Science and Technology,

Office of Water. October 15, 1998. EPA 815-B-98-008. PB 99-111361.

95. U.S. EPA. 1998e. Health Risk Assessment/Characterization of the

Drinking Water Disinfection Byproduct Bromate. Office of Science and

Technology, Office of Water. September 30, 1998. EPA 815-B-98-007.

PB 99-111353.

96. U.S. EPA. 1998f. Panel Report and Recommendation for Conducting

Epidemiological Research on Possible Reproductive and Developmental

Effects of Exposure to Disinfected Drinking Water. Office of

Research and Development. February 12, 1998.

97. U.S. EPA. 1998g. Regulatory Impact Analysis of Final

Disinfectant/Disinfection By-Products Regulations. Washington, D.C.

EPA Number 815-B-98-002. PB 99-111304.

98. U.S. EPA. 1998h. Health Risks to Fetuses, Infants, and Children

(final Stage 1 DBP Rule). Office of Science and Technology. Office

of Water. November 19, 1998. EPA 815-B-98-009. PB 99-111379.

99. U.S. EPA. 1998i. Revisions to State Primacy Requirements To

Implement Safe Drinking Water Act Amendments: Final Rule. Federal

Register, Tuesday, April 28, 1998, Vol. 63, No.81, 23362-23368.

100. U.S. EPA. 1998j. Revision of Existing Variance and Exemption

Regulations to Comply with Requirements of the Safe Drinking Water

Act; Final Rule. Federal Register, Vol 63, No. 157. Friday, Aug. 14,

1998. pp. 43833-43851.

101. U.S. EPA. 1998k. Cost and Technology Document for Controlling

Disinfectants and Disinfection Byproducts. Office of Ground Water

and Drinking Water. Washington, DC. EPA 815-R-98-014. PB 99-111486.

102. U.S. EPA. 1998l. Synthesis of the Peer-Review of Meta-analysis

of Epidemiologic Data on Risks of Cancer from Chlorinated Drinking

Water. National Center for Environmental Assessment, Office of

Research and Development, February 16, 1998.

103. U.S. EPA. 1998m. NCEA Position Paper Regarding Risk Assessment

Use of the Results from the Published Study: Morris et al. Am J

Public Health 1992;82:955-963. National Center for Environmental

Assessment, Office of Research and Development, October 7, 1997.

104. U.S. EPA. 1998n. A Suggested Approach for Using the Current

Epidemiologic Literature to Estimate the Possible Cancer Risk from

Water Chlorination, for the Purposes of the Regulatory Impact

Analysis. ORD, National Center for Environmental Assessment. August

27, 1998.

105. U.S. EPA. 1998o. Unfunded Mandates Reform Act Analysis for the

Stage 1 Disinfectant and Disinfection Byproduct Rule. Office of

Groundwater and Drinking Water.

106. U.S. EPA. 1998p. Health Risk Assessment/Characterization of the

Drinking Water Disinfection Byproduct Chloroform. Office of Science

and Technology, Office of Water. November 4, 1998. EPA 815-B-98-006.

PB 99-111346.

107. U.S. EPA. 1998q. Small System Compliance Technology List for

the Stage 1 DBP Rule. Office of Groundwater and Drinking Water. EPA

815-R-98-017. PB 99-111510.

108. U.S. EPA. 1998r. Technologies and Costs for Point-of-Entry

(POE) and Point-of-Use (POU) Devices for Control of Disinfection

Byproducts. Office of Groundwater and Drinking Water. EPA 815-R-98-

016. PB 99-111502.

109. U.S. EPA. 1998s. National-Level Affordability Criteria Under

the 1996 Amendments to the Safe Drinking Water Act. Office of

Groundwater and Drinking Water. August 19, 1998.

110. U.S. EPA. 1998t. Variance Technology Findings for Contaminants

Regulated Before 1996. Office of Water. September 1998. EPA 815-R-

98-003.

111. U.S. EPA. 1998u. Occurrence Assessment for Disinfectants and

Disinfection Byproducts in Public Drinking Water Supplies. Office of

Groundwater and Drinking Water. EPA 815-B-98-004. November 13, 1998.

PB 99-111320.

112. USGS. 1989. Method I-1030-85. Techniques of Water Resources

Investigations of the U.S. Geological Survey. Book 5, Chapter A-1,

3rd ed., U.S. Government Printing Office.

113. Waller K., Swan S. H., DeLorenze G., Hopkins B., 1998.

Trihalomethanes in drinking water and spontaneous abortion.

Epidemiology. 9(2):134-140.



[[Page 69463]]



114. White, M. C., Thompson, D., Harrington, G. W., and P.S. Singer.

1997. Evaluating Criteria for Enhanced Coagulation Compliance. AWWA,

89:5:64.

115. Xie, Yuefeng. 1995. Effects of Sodium Chloride on DBP

Analytical Results, Extended Abstract, Division of Environmental

Chemistry, American Chemical Society Annual Conference, Chicago, IL,

Aug. 21-26, 1995.



List of Subjects



40 CFR Part 9



    Environmental protection, Reporting and recordkeeping requirements.



40 CFR Parts 141 and 142



    Analytical methods, Drinking water, Environmental protection,

Incorporation by reference, Intergovernmental relations, Public

utilities, Reporting and recordkeeping requirements, Utilities, Water

supply.



    Dated: November 30, 1998.

Carol M. Browner,

Administrator.



    For the reasons set out in the preamble, title 40, chapter I of the

Code of Federal Regulations is amended as follows:



PART 9--[AMENDED]



    1. The authority citation for part 9 continues to read as follows:



    Authority: 7 U.S.C. 135 et seq., 136-136y; 15 U.S.C. 2001, 2003,

2005, 2006, 2601-2671; 21 U.S.C. 331j, 346a, 348; 31 U.S.C. 9701; 33

U.S.C. 1251 et seq., 1311, 1313d, 1314, 1318, 1321, 1326, 1330,

1342, 1344, 1345 (d) and (e), 1361; E.O. 11735, 38 FR 21243, 3 CFR,

1971-1975 Comp. p. 973; 42 U.S.C. 241, 242b, 243, 246, 300f, 300g,

300g-1, 300g-2, 300g-3, 300g-4, 300g-5, 300g-6, 300j-1, 300j-2,

300j-3, 300j-4, 300j-9, 1857 et seq., 6901-6992k, 7401-7671q, 7542,

9601-9657, 11023, 11048.



    2. In Sec. 9.1 the table is amended by adding under the indicated

heading: the new entries in numerical order to read as follows:





Sec. 9.1  OMB approvals under the Paperwork Reduction Act.



* * * * *



------------------------------------------------------------------------

                                                             OMB control

                      40 CFR citation                            No.

------------------------------------------------------------------------



                  *        *        *        *        *

National Primary Drinking Water Regulations



                  *        *        *        *        *

141.130-141.132............................................    2040-0204

141.134-141.135............................................    2040-0204



                  *        *        *        *        *

------------------------------------------------------------------------



PART 141--NATIONAL PRIMARY DRINKING WATER REGULATIONS



    3. The authority citation for part 141 continues to read as

follows:



    Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-

5, 300g-6, 300j-4, 300j-9, and 300j-11.



    4. Section 141.2 is amended by adding the following definitions in

alphabetical order to read as follows:





Sec. 141.2  Definitions.



* * * * *

    Enhanced coagulation means the addition of sufficient coagulant for

improved removal of disinfection byproduct precursors by conventional

filtration treatment.

* * * * *

    Enhanced softening means the improved removal of disinfection

byproduct precursors by precipitative softening.

* * * * *

    GAC10 means granular activated carbon filter beds with an empty-bed

contact time of 10 minutes based on average daily flow and a carbon

reactivation frequency of every 180 days.

* * * * *

    Haloacetic acids (five) (HAA5) mean the sum of the concentrations

in milligrams per liter of the haloacetic acid compounds

(monochloroacetic acid, dichloroacetic acid, trichloroacetic acid,

monobromoacetic acid, and dibromoacetic acid), rounded to two

significant figures after addition.

* * * * *

    Maximum residual disinfectant level (MRDL) means a level of a

disinfectant added for water treatment that may not be exceeded at the

consumer's tap without an unacceptable possibility of adverse health

effects. For chlorine and chloramines, a PWS is in compliance with the

MRDL when the running annual average of monthly averages of samples

taken in the distribution system, computed quarterly, is less than or

equal to the MRDL. For chlorine dioxide, a PWS is in compliance with

the MRDL when daily samples are taken at the entrance to the

distribution system and no two consecutive daily samples exceed the

MRDL. MRDLs are enforceable in the same manner as maximum contaminant

levels under Section 1412 of the Safe Drinking Water Act. There is

convincing evidence that addition of a disinfectant is necessary for

control of waterborne microbial contaminants. Notwithstanding the MRDLs

listed in Sec. 141.65, operators may increase residual disinfectant

levels of chlorine or chloramines (but not chlorine dioxide) in the

distribution system to a level and for a time necessary to protect

public health to address specific microbiological contamination

problems caused by circumstances such as distribution line breaks,

storm runoff events, source water contamination, or cross-connections.

* * * * *

    Maximum residual disinfectant level goal (MRDLG) means the maximum

level of a disinfectant added for water treatment at which no known or

anticipated adverse effect on the health of persons would occur, and

which allows an adequate margin of safety. MRDLGs are nonenforceable

health goals and do not reflect the benefit of the addition of the

chemical for control of waterborne microbial contaminants.

* * * * *

    Subpart H systems means public water systems using surface water or

ground water under the direct influence of surface water as a source

that are subject to the requirements of subpart H of this part.

* * * * *

    SUVA means Specific Ultraviolet Absorption at 254 nanometers (nm),

an indicator of the humic content of water. It is a calculated

parameter obtained by dividing a sample's ultraviolet absorption at a

wavelength of 254 nm (UV <INF>254</INF>) (in m <SUP>=1</SUP>) by its

concentration of dissolved organic carbon (DOC) (in mg/L).

* * * * *

    Total Organic Carbon (TOC) means total organic carbon in mg/L

measured using heat, oxygen, ultraviolet irradiation, chemical

oxidants, or combinations of these oxidants that convert organic carbon

to carbon dioxide, rounded to two significant figures.

* * * * *

    5. Section 141.12 is revised to read as follows:





Sec. 141.12  Maximum contaminant levels for total trihalomethanes.



    The maximum contaminant level of 0.10 mg/L for total

trihalomethanes (the sum of the concentrations of bromodichloromethane,

dibromochloromethane, tribromomethane (bromoform), and trichloromethane

(chloroform)) applies to subpart H community water systems which serve

a population of 10,000 people or more until December 16, 2001. This

level applies to community water systems that use only ground water not

under the direct influence of surface water and serve a population of

10,000 people or more until December



[[Page 69464]]



16, 2003. Compliance with the maximum contaminant level for total

trihalomethanes is calculated pursuant to Sec. 141.30. After December

16, 2003, this section is no longer applicable.

    6. Section 141.30 is amended by revising the the first sentences in

paragraphs (d) and (f) and adding paragraph (h) to read as follows:





Sec. 141.30  Total trihalomethanes sampling, analytical and other

requirements.



* * * * *

    (d) Compliance with Sec. 141.12 shall be determined based on a

running annual average of quarterly samples collected by the system as

prescribed in paragraph (b)(1) or (2) of this section. * * *

* * * * *

    (f) Before a community water system makes any significant

modifications to its existing treatment process for the purposes of

achieving compliance with Sec. 141.12, such system must submit and

obtain State approval of a detailed plan setting forth its proposed

modification and those safeguards that it will implement to ensure that

the bacteriological quality of the drinking water served by such system

will not be adversely affected by such modification. * * *

* * * * *

    (h) The requirements in paragraphs (a) through (g) of this section

apply to subpart H community water systems which serve a population of

10,000 or more until December 16, 2001. The requirements in paragraphs

(a) through (g) of this section apply to community water systems which

use only ground water not under the direct influence of surface water

that add a disinfectant (oxidant) in any part of the treatment process

and serve a population of 10,000 or more until December 16, 2003. After

December 16, 2003, this section is no longer applicable.

    7. Section 141.32 is amended by revising the heading in paragraph

(a) introductory text, the first sentence of paragraph (a)(1)(iii)

introductory text, and the first sentence of paragraph (c), and adding

paragraphs (a)(1)(iii)(E) and (e) (76) through (81), to read as

follows:





Sec. 141.32  Public notification.



* * * * *

    (a) Maximum contaminant levels (MCLs), maximum residual

disinfectant levels (MRDLs). * * *

    (1) * * *

    (iii) For violations of the MCLs of contaminants or MRDLs of

disinfectants that may pose an acute risk to human health, by

furnishing a copy of the notice to the radio and television stations

serving the area served by the public water system as soon as possible

but in no case later than 72 hours after the violation. ***

* * * * *

    (E) Violation of the MRDL for chlorine dioxide as defined in

Sec. 141.65 and determined according to Sec. 141.133(c)(2).

* * * * *

    (c) * * * The owner or operator of a community water system must

give a copy of the most recent public notice for any outstanding

violation of any maximum contaminant level, or any maximum residual

disinfectant level, or any treatment technique requirement, or any

variance or exemption schedule to all new billing units or new hookups

prior to or at the time service begins.

* * * * *

    (e) * * *

    (76) Chlorine. The United States Environmental Protection Agency

(EPA) sets drinking water standards and has determined that chlorine is

a health concern at certain levels of exposure. Chlorine is added to

drinking water as a disinfectant to kill bacteria and other disease-

causing microorganisms and is also added to provide continuous

disinfection throughout the distribution system. Disinfection is

required for surface water systems. However, at high doses for extended

periods of time, chlorine has been shown to affect blood and the liver

in laboratory animals. EPA has set a drinking water standard for

chlorine to protect against the risk of these adverse effects. Drinking

water which meets this EPA standard is associated with little to none

of this risk and should be considered safe with respect to chlorine.

    (77) Chloramines. The United States Environmental Protection Agency

(EPA) sets drinking water standards and has determined that chloramines

are a health concern at certain levels of exposure. Chloramines are

added to drinking water as a disinfectant to kill bacteria and other

disease-causing microorganisms and are also added to provide continuous

disinfection throughout the distribution system. Disinfection is

required for surface water systems. However, at high doses for extended

periods of time, chloramines have been shown to affect blood and the

liver in laboratory animals. EPA has set a drinking water standard for

chloramines to protect against the risk of these adverse effects.

Drinking water which meets this EPA standard is associated with little

to none of this risk and should be considered safe with respect to

chloramines.

    (78) Chlorine dioxide. The United States Environmental Protection

Agency (EPA) sets drinking water standards and has determined that

chlorine dioxide is a health concern at certain levels of exposure.

Chlorine dioxide is used in water treatment to kill bacteria and other

disease-causing microorganisms and can be used to control tastes and

odors. Disinfection is required for surface water systems. However, at

high doses, chlorine dioxide-treated drinking water has been shown to

affect blood in laboratory animals. Also, high levels of chlorine

dioxide given to laboratory animals in drinking water have been shown

to cause neurological effects on the developing nervous system. These

neurodevelopmental effects may occur as a result of a short-term

excessive chlorine dioxide exposure. To protect against such

potentially harmful exposures, EPA requires chlorine dioxide monitoring

at the treatment plant, where disinfection occurs, and at

representative points in the distribution system serving water users.

EPA has set a drinking water standard for chlorine dioxide to protect

against the risk of these adverse effects.



    Note: In addition to the language in this introductory text of

paragraph (e)(78), systems must include either the language in

paragraph (e)(78)(i) or (e)(78)(ii) of this section. Systems with a

violation at the treatment plant, but not in the distribution

system, are required to use the language in paragraph (e)(78)(i) of

this section and treat the violation as a nonacute violation.

Systems with a violation in the distribution system are required to

use the language in paragraph (e)(78)(ii) of this section and treat

the violation as an acute violation.



    (i) The chlorine dioxide violations reported today are the result

of exceedances at the treatment facility only, and do not include

violations within the distribution system serving users of this water

supply. Continued compliance with chlorine dioxide levels within the

distribution system minimizes the potential risk of these violations to

present consumers.

    (ii) The chlorine dioxide violations reported today include

exceedances of the EPA standard within the distribution system serving

water users. Violations of the chlorine dioxide standard within the

distribution system may harm human health based on short-term

exposures. Certain groups, including pregnant women, infants, and young

children, may be especially susceptible to adverse effects of excessive

exposure to chlorine dioxide-treated water. The purpose of this notice

is to advise that such persons should consider reducing their risk of

adverse effects from these chlorine dioxide violations by seeking

alternate sources of water for human consumption until such exceedances

are rectified. Local



[[Page 69465]]



and State health authorities are the best sources for information

concerning alternate drinking water.

    (79) Disinfection byproducts and treatment technique for DBPs. The

United States Environmental Protection Agency (EPA) sets drinking water

standards and requires the disinfection of drinking water. However,

when used in the treatment of drinking water, disinfectants react with

naturally-occurring organic and inorganic matter present in water to

form chemicals called disinfection byproducts (DBPs). EPA has

determined that a number of DBPs are a health concern at certain levels

of exposure. Certain DBPs, including some trihalomethanes (THMs) and

some haloacetic acids (HAAs), have been shown to cause cancer in

laboratory animals. Other DBPs have been shown to affect the liver and

the nervous system, and cause reproductive or developmental effects in

laboratory animals. Exposure to certain DBPs may produce similar

effects in people. EPA has set standards to limit exposure to THMs,

HAAs, and other DBPs.

    (80) Bromate. The United States Environmental Protection Agency

(EPA) sets drinking water standards and has determined that bromate is

a health concern at certain levels of exposure. Bromate is formed as a

byproduct of ozone disinfection of drinking water. Ozone reacts with

naturally occurring bromide in the water to form bromate. Bromate has

been shown to produce cancer in rats. EPA has set a drinking water

standard to limit exposure to bromate.

    (81) Chlorite. The United States Environmental Protection Agency

(EPA) sets drinking water standards and has determined that chlorite is

a health concern at certain levels of exposure. Chlorite is formed from

the breakdown of chlorine dioxide, a drinking water disinfectant.

Chlorite in drinking water has been shown to affect blood and the

developing nervous system. EPA has set a drinking water standard for

chlorite to protect against these effects. Drinking water which meets

this standard is associated with little to none of these risks and

should be considered safe with respect to chlorite.

* * * * *

    8. Subpart F is amended by revising the subpart heading and adding

Secs. 141.53 and 141.54 to read as follows:



Subpart F--Maximum Contaminant Level Goals and Maximum Residual

Disinfectant Level Goals



* * * * *





Sec. 141.53--Maximum contaminant level goals for disinfection

byproducts.



    MCLGs for the following disinfection byproducts are as indicated:



------------------------------------------------------------------------

                                                                MCLG (mg/

                    Disinfection byproduct                         L)

------------------------------------------------------------------------

Chloroform....................................................   Zero

Bromodichloromethane..........................................   Zero

Bromoform.....................................................   Zero

Bromate.......................................................   Zero

Dichloroacetic acid...........................................   Zero

Trichloroacetic acid..........................................      0.3

Chlorite......................................................      0.8

Dibromochloromethane..........................................      0.06

------------------------------------------------------------------------



Sec. 141.54  Maximum residual disinfectant level goals for

disinfectants.



    MRDLGs for disinfectants are as follows:



------------------------------------------------------------------------

          Disinfectant residual                     MRDLG(mg/L)

------------------------------------------------------------------------

Chlorine................................  4 (as Cl <INF>2).

Chloramines.............................  4 (as Cl <INF>2).

Chlorine dioxide........................  0.8 (as ClO<INF>2)

------------------------------------------------------------------------



    9. Subpart G is amended by revising the subpart heading and adding

Secs. 141.64 and 141.65 to read as follows:



Subpart G--National Revised Primary Drinking Water Regulations:

Maximum Contaminant Levels and Maximum Residual Disinfectant Levels



* * * * *





Sec. 141.64  Maximum contaminant levels for disinfection byproducts.



    (a) The maximum contaminant levels (MCLs) for disinfection

byproducts are as follows:



------------------------------------------------------------------------

                                                                MCL (mg/

                    Disinfection byproduct                         L)

------------------------------------------------------------------------

Total trihalomethanes (TTHM)..................................     0.080

Haloacetic acids (five) (HAA5)................................     0.060

Bromate.......................................................     0.010

Chlorite......................................................     1.0

------------------------------------------------------------------------



    (b) Compliance dates. (1) CWSs and NTNCWSs. Subpart H systems

serving 10,000 or more persons must comply with this section beginning

December 16, 2001. Subpart H systems serving fewer than 10,000 persons

and systems using only ground water not under the direct influence of

surface water must comply with this section beginning December 16,

2003.

    (2) A system that is installing GAC or membrane technology to

comply with this section may apply to the State for an extension of up

to 24 months past the dates in paragraphs (b)(1) of this section, but

not beyond December 16, 2003. In granting the extension, States must

set a schedule for compliance and may specify any interim measures that

the system must take. Failure to meet the schedule or interim treatment

requirements constitutes a violation of a National Primary Drinking

Water Regulation.

    (c) The Administrator, pursuant to Section 1412 of the Act, hereby

identifies the following as the best technology, treatment techniques,

or other means available for achieving compliance with the maximum

contaminant levels for disinfection byproducts identified in paragraph

(a) of this section:



------------------------------------------------------------------------

         Disinfection byproduct             Best available technology

------------------------------------------------------------------------

TTHM...................................  Enhanced coagulation or

                                          enhanced softening or GAC10,

                                          with chlorine as the primary

                                          and residual disinfectant

HAA5...................................  Enhanced coagulation or

                                          enhanced softening or GAC10,

                                          with chlorine as the primary

                                          and residual disinfectant.

Bromate................................  Control of ozone treatment

                                          process to reduce production

                                          of bromate.

Chlorite...............................  Control of treatment processes

                                          to reduce disinfectant demand

                                          and control of disinfection

                                          treatment processes to reduce

                                          disinfectant levels.

------------------------------------------------------------------------



Sec. 141.65  Maximum residual disinfectant levels.



    (a) Maximum residual disinfectant levels (MRDLs) are as follows:



------------------------------------------------------------------------

          Disinfectant residual                     MRDL (mg/L)

------------------------------------------------------------------------

Chlorine................................  4.0 (as Cl<INF>2).

Chloramines.............................  4.0 (as Cl<INF>2).

Chlorine dioxide........................  0.8 (as ClO<INF>2).

------------------------------------------------------------------------



    (b) Compliance dates.

    (1) CWSs and NTNCWSs. Subpart H systems serving 10,000 or more

persons must comply with this section beginning December 16, 2001.

Subpart H systems serving fewer than 10,000 persons and systems using

only ground water not under the direct influence of surface water must

comply with this subpart beginning December 16, 2003.

    (2) Transient NCWSs. Subpart H systems serving 10,000 or more

persons and using chlorine dioxide as a disinfectant or oxidant must

comply with the chlorine dioxide MRDL beginning December 16, 2001.

Subpart H systems serving fewer than 10,000 persons and using chlorine

dioxide as a disinfectant or oxidant and systems using only ground

water not under the direct influence of surface water and using

chlorine dioxide as a disinfectant or oxidant must comply with the



[[Page 69466]]



chlorine dioxide MRDL beginning December 16, 2003.

    (c) The Administrator, pursuant to Section 1412 of the Act, hereby

identifies the following as the best technology, treatment techniques,

or other means available for achieving compliance with the maximum

residual disinfectant levels identified in paragraph (a) of this

section: control of treatment processes to reduce disinfectant demand

and control of disinfection treatment processes to reduce disinfectant

levels.

    10. A new subpart L is added to read as follows:



Subpart L--Disinfectant Residuals, Disinfection Byproducts, and

Disinfection Byproduct Precursors



Sec.

141.130 General requirements.

141.131 Analytical requirements.

141.132 Monitoring requirements.

141.133 Compliance requirements.

141.134 Reporting and recordkeeping requirements.

141.135 Treatment technique for control of disinfection byproduct

(DBP) precursors.





Sec. 141.130  General requirements.



    (a) The requirements of this subpart L constitute national primary

drinking water regulations.

    (1) The regulations in this subpart establish criteria under which

community water systems (CWSs) and nontransient, noncommunity water

systems (NTNCWSs) which add a chemical disinfectant to the water in any

part of the drinking water treatment process must modify their

practices to meet MCLs and MRDLs in Secs. 141.64 and 141.65,

respectively, and must meet the treatment technique requirements for

disinfection byproduct precursors in Sec. 141.135.

    (2) The regulations in this subpart establish criteria under which

transient NCWSs that use chlorine dioxide as a disinfectant or oxidant

must modify their practices to meet the MRDL for chlorine dioxide in

Sec. 141.65.

    (3) EPA has established MCLs for TTHM and HAA5 and treatment

technique requirements for disinfection byproduct precursors to limit

the levels of known and unknown disinfection byproducts which may have

adverse health effects. These disinfection byproducts may include

chloroform; bromodichloromethane; dibromochloromethane; bromoform;

dichloroacetic acid; and trichloroacetic acid.

    (b) Compliance dates. (1) CWSs and NTNCWSs. Unless otherwise noted,

systems must comply with the requirements of this subpart as follows.

Subpart H systems serving 10,000 or more persons must comply with this

subpart beginning December 16, 2001. Subpart H systems serving fewer

than 10,000 persons and systems using only ground water not under the

direct influence of surface water must comply with this subpart

beginning December 16, 2003.

    (2) Transient NCWSs. Subpart H systems serving 10,000 or more

persons and using chlorine dioxide as a disinfectant or oxidant must

comply with any requirements for chlorine dioxide and chlorite in this

subpart beginning December 16, 2001. Subpart H systems serving fewer

than 10,000 persons and using chlorine dioxide as a disinfectant or

oxidant and systems using only ground water not under the direct

influence of surface water and using chlorine dioxide as a disinfectant

or oxidant must comply with any requirements for chlorine dioxide and

chlorite in this subpart beginning December 16, 2003.

    (c) Each CWS and NTNCWS regulated under paragraph (a) of this

section must be operated by qualified personnel who meet the

requirements specified by the State and are included in a State

register of qualified operators.

    (d) Control of disinfectant residuals. Notwithstanding the MRDLs in

Sec. 141.65, systems may increase residual disinfectant levels in the

distribution system of chlorine or chloramines (but not chlorine

dioxide) to a level and for a time necessary to protect public health,

to address specific microbiological contamination problems caused by

circumstances such as, but not limited to, distribution line breaks,

storm run-off events, source water contamination events, or cross-

connection events.





Sec. 141.131  Analytical requirements.



    (a) General. (1) Systems must use only the analytical method(s)

specified in this section, or otherwise approved by EPA for monitoring

under this subpart, to demonstrate compliance with the requirements of

this subpart. These methods are effective for compliance monitoring

February 16, 1999.

    (2) The following documents are incorporated by reference. The

Director of the Federal Register approves this incorporation by

reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies

may be inspected at EPA's Drinking Water Docket, 401 M Street, SW,

Washington, DC 20460, or at the Office of the Federal Register, 800

North Capitol Street, NW, Suite 700, Washington DC. EPA Method 552.1 is

in Methods for the Determination of Organic Compounds in Drinking

Water-Supplement II, USEPA, August 1992, EPA/600/R-92/129 (available

through National Information Technical Service (NTIS), PB92-207703).

EPA Methods 502.2, 524.2, 551.1, and 552.2 are in Methods for the

Determination of Organic Compounds in Drinking Water-Supplement III,

USEPA, August 1995, EPA/600/R-95/131. (available through NTIS, PB95-

261616). EPA Method 300.0 is in Methods for the Determination of

Inorganic Substances in Environmental Samples, USEPA, August 1993, EPA/

600/R-93/100. (available through NTIS, PB94-121811). EPA Method 300.1

is titled USEPA Method 300.1, Determination of Inorganic Anions in

Drinking Water by Ion Chromatography, Revision 1.0, USEPA, 1997, EPA/

600/R-98/118 (available through NTIS, PB98-169196); also available

from: Chemical Exposure Research Branch, Microbiological & Chemical

Exposure Assessment Research Division, National Exposure Research

Laboratory, U.S. Environmental Protection Agency, Cincinnati, OH 45268,

Fax Number: 513-569-7757, Phone number: 513-569-7586. Standard Methods

4500-Cl D, 4500-Cl E, 4500-Cl F, 4500-Cl G, 4500-Cl H, 4500-Cl I, 4500-

ClO<INF>2</INF> D, 4500-ClO<INF>2</INF> E, 6251 B, and 5910 B shall be

followed in accordance with Standard Methods for the Examination of

Water and Wastewater, 19th Edition, American Public Health Association,

1995; copies may be obtained from the American Public Health

Association, 1015 Fifteenth Street, NW, Washington, DC 20005. Standard

Methods 5310 B, 5310 C, and 5310 D shall be followed in accordance with

the Supplement to the 19th Edition of Standard Methods for the

Examination of Water and Wastewater, American Public Health

Association, 1996; copies may be obtained from the American Public

Health Association, 1015 Fifteenth Street, NW, Washington, DC 20005.

ASTM Method D 1253-86 shall be followed in accordance with the Annual

Book of ASTM Standards, Volume 11.01, American Society for Testing and

Materials, 1996 edition; copies may be obtained from the American

Society for Testing and Materials, 100 Barr Harbor Drive, West

Conshohoken, PA 19428.

    (b) Disinfection byproducts. (1) Systems must measure disinfection

byproducts by the methods (as modified by the footnotes) listed in the

following table:



[[Page 69467]]







                                            Approved Methods for Disinfection Byproduct Compliance Monitoring

--------------------------------------------------------------------------------------------------------------------------------------------------------

                                                                                                                  Byproduct measured \1\

              Methodology \2\                EPA method              Standard method             -------------------------------------------------------

                                                                                                      TTHM          HAA5      Chlorite \4\     Bromate

--------------------------------------------------------------------------------------------------------------------------------------------------------

P&T/GC/ElCD & PID.........................     \3\502.2                                                     X

P&T/GC/MS.................................        524.2                                                     X

LLE/GC/ECD................................        551.1                                                     X

LLE/GC/ECD................................               6251 B                                                           X

SPE/GC/ECD................................        552.1                                                                   X

LLE/GC/ECD................................        552.2                                                                   X

Amperometric Titration....................               4500-ClO<INF>2 E                                                                    X

IC........................................        300.0                                                                                 X

IC........................................        300.1                                                                                 X             X

--------------------------------------------------------------------------------------------------------------------------------------------------------

\1\ X indicates method is approved for measuring specified disinfection byproduct.

\2\ P&T = purge and trap; GC = gas chromatography; ElCD = electrolytic conductivity detector; PID = photoionization detector; MS = mass spectrometer;

  LLE = liquid/liquid extraction; ECD = electron capture detector; SPE = solid phase extractor; IC = ion chromatography.

\3\ If TTHMs are the only analytes being measured in the sample, then a PID is not required.

\4\ Amperometric titration may be used for routine daily monitoring of chlorite at the entrance to the distribution system, as prescribed in Sec.

  141.132(b)(2)(i)(A). Ion chromatography must be used for routine monthly monitoring of chlorite and additional monitoring of chlorite in the

  distribution system, as prescribed in Sec.  141.132(b)(2)(i)(B) and (b)(2)(ii).



    (2) Analysis under this section for disinfection byproducts must be

conducted by laboratories that have received certification by EPA or

the State. To receive certification to conduct analyses for the

contaminants in Sec. 141.64(a), the laboratory must carry out annual

analyses of performance evaluation (PE) samples approved by EPA or the

State. In these analyses of PE samples, the laboratory must achieve

quantitative results within the acceptance limit on a minimum of 80% of

the analytes included in each PE sample. The acceptance limit is

defined as the 95% confidence interval calculated around the mean of

the PE study data between a maximum and minimum acceptance limit of +/

-50% and +/-15% of the study mean.

    (c) Disinfectant residuals. (1) Systems must measure residual

disinfectant concentrations for free chlorine, combined chlorine

(chloramines), and chlorine dioxide by the methods listed in the

following table:



                                            Approved Methods for Disinfectant Residual Compliance Monitoring

--------------------------------------------------------------------------------------------------------------------------------------------------------

                                                                                                                   Residual Measured \1\

                                                                                                 -------------------------------------------------------

             Methodology                    Standard  method                 ASTM method              Free        Combined        Total       Chlorine

                                                                                                    chlorine      chlorine      chlorine       dioxide

--------------------------------------------------------------------------------------------------------------------------------------------------------

Amperometric Titration..............  4500-Cl D                     D 1253-86                               X             X             X

Low Level Amperometric Titration....  4500-Cl E                                                                                         X

DPD Ferrous Titrimetric.............  4500-Cl F                                                             X             X             X

DPD Colorimetric....................  4500-Cl G                                                             X             X             X

Syringaldazin e (FACTS).............  4500-Cl H                                                             X

Iodometric Electrode................  4500-Cl I                                                                                         X

DPD.................................  4500-ClO<INF>2 D                                                                                                     X

Amperometric Method II..............  4500-ClO<INF>2 E                                                                                                     X

--------------------------------------------------------------------------------------------------------------------------------------------------------

\1\ X indicates method is approved for measuring specified disinfectant residual.



    (2) If approved by the State, systems may also measure residual

disinfectant concentrations for chlorine, chloramines, and chlorine

dioxide by using DPD colorimetric test kits.

    (3) A party approved by EPA or the State must measure residual

disinfectant concentration.

    (d) Additional analytical methods. Systems required to analyze

parameters not included in paragraphs (b) and (c) of this section must

use the following methods. A party approved by EPA or the State must

measure these parameters.

    (1) Alkalinity. All methods allowed in Sec. 141.89(a) for measuring

alkalinity.

    (2) Bromide. EPA Method 300.0 or EPA Method 300.1.

    (3) Total Organic Carbon (TOC). Standard Method 5310 B (High-

Temperature Combustion Method) or Standard Method 5310 C (Persulfate-

Ultraviolet or Heated-Persulfate Oxidation Method) or Standard Method

5310 D (Wet-Oxidation Method). TOC samples may not be filtered prior to

analysis. TOC samples must either be analyzed or must be acidified to

achieve pH less than 2.0 by minimal addition of phosphoric or sulfuric

acid as soon as practical after sampling, not to exceed 24 hours.

Acidified TOC samples must be analyzed within 28 days.

    (4) Specific Ultraviolet Absorbance (SUVA). SUVA is equal to the UV

absorption at 254nm (UV<INF>254</INF>) (measured in m-\1\ divided by

the dissolved organic carbon (DOC) concentration (measured as mg/L). In

order to determine SUVA, it is necessary to separately measure

UV<INF>254</INF> and DOC. When determining SUVA, systems must use the

methods stipulated in paragraph (d)(4)(i) of this section to measure

DOC and the method stipulated in paragraph (d)(4)(ii) of this section

to measure UV<INF>254</INF>. SUVA must be determined on water prior to

the addition of disinfectants/oxidants by the system. DOC and

UV<INF>254</INF> samples used to determine a SUVA value must be taken

at the same time and at the same location.

    (i) Dissolved Organic Carbon (DOC). Standard Method 5310 B (High-

Temperature Combustion Method) or Standard Method 5310 C (Persulfate-

Ultraviolet or Heated-Persulfate Oxidation Method) or Standard Method



[[Page 69468]]



5310 D (Wet-Oxidation Method). Prior to analysis, DOC samples must be

filtered through a 0.45 <greek-m>m pore-diameter filter. Water passed

through the filter prior to filtration of the sample must serve as the

filtered blank. This filtered blank must be analyzed using procedures

identical to those used for analysis of the samples and must meet the

following criteria: DOC < 0.5 mg/L. DOC samples must be filtered

through the 0.45 <greek-m>m pore-diameter filter prior to

acidification. DOC samples must either be analyzed or must be acidified

to achieve pH less than 2.0 by minimal addition of phosphoric or

sulfuric acid as soon as practical after sampling, not to exceed 48

hours. Acidified DOC samples must be analyzed within 28 days.

    (ii) Ultraviolet Absorption at 254 nm (UV<INF>254</INF>). Method

5910 B (Ultraviolet Absorption Method). UV absorption must be measured

at 253.7 nm (may be rounded off to 254 nm). Prior to analysis,

UV<INF>254</INF> samples must be filtered through a 0.45 <greek-m>m

pore-diameter filter. The pH of UV<INF>254</INF> samples may not be

adjusted. Samples must be analyzed as soon as practical after sampling,

not to exceed 48 hours.

    (5) pH. All methods allowed in Sec. 141.23(k)(1) for measuring pH.





Sec. 141.132  Monitoring requirements.



    (a) General requirements. (1) Systems must take all samples during

normal operating conditions.

    (2) Systems may consider multiple wells drawing water from a single

aquifer as one treatment plant for determining the minimum number of

TTHM and HAA5 samples required, with State approval in accordance with

criteria developed under Sec. 142.16(f)(5) of this chapter.

    (3) Failure to monitor in accordance with the monitoring plan

required under paragraph (f) of this section is a monitoring violation.

    (4) Failure to monitor will be treated as a violation for the

entire period covered by the annual average where compliance is based

on a running annual average of monthly or quarterly samples or averages

and the system's failure to monitor makes it impossible to determine

compliance with MCLs or MRDLs.

    (5) Systems may use only data collected under the provisions of

this subpart or subpart M of this part to qualify for reduced

monitoring.

    (b) Monitoring requirements for disinfection byproducts. (1) TTHMs

and HAA5. (i) Routine monitoring. Systems must monitor at the frequency

indicated in the following table:



                                 Routine Monitoring Frequency for TTHM and HAA5

----------------------------------------------------------------------------------------------------------------

                                          Minimum monitoring

           Type of system                     frequency             Sample location in the distribution system

----------------------------------------------------------------------------------------------------------------

Subpart H system serving at least    Four water samples per       At least 25 percent of all samples collected

10,000 persons.                      quarter per treatment        each quarter at locations representing

                                      plant.                       maximum residence time. Remaining samples

                                                                   taken at locations representative of at least

                                                                   average residence time in the distribution

                                                                   system and representing the entire

                                                                   distribution system, taking into account

                                                                   number of persons served, different sources

                                                                   of water, and different treatment methods.\1\

Subpart H system serving from 500    One water sample per         Locations representing maximum residence

to 9,999 persons.                    quarter per treatment        time.\1\

                                      plant.

Subpart H system serving fewer than  One sample per year per      Locations representing maximum residence

500 persons.                         treatment plant during       time.\1\ If the sample (or average of annual

                                      month of warmest water       samples, if more than one sample is taken)

                                      temperature.                 exceeds MCL, system must increase monitoring

                                                                   to one sample per treatment plant per

                                                                   quarter, taken at a point reflecting the

                                                                   maximum residence time in the distribution

                                                                   system, until system meets reduced monitoring

                                                                   criteria in paragraph (c) of this section.

System using only ground water not   One water sample per         Locations representing maximum residence

under direct influence of surface    quarter per treatment        time.\1\

water using chemical disinfectant    plant \2\.

and serving at least 10,000

persons.

System using only ground water not   One sample per year per      Locations representing maximum residence

under direct influence of surface    treatment plant \2\ during   time.\1\ If the sample (or average of annual

water using chemical disinfectant    month of warmest water       samples, if more than one sample is taken)

and serving fewer than 10,000        temperature.                 exceeds MCL, system must increase monitoring

persons.                                                          to one sample per treatment plant per

                                                                   quarter, taken at a point reflecting the

                                                                   maximum residence time in the distribution

                                                                   system, until system meets criteria in

                                                                   paragraph (c) of this section for reduced

                                                                   monitoring.

----------------------------------------------------------------------------------------------------------------

\1\ If a system elects to sample more frequently than the minimum required, at least 25 percent of all samples

  collected each quarter (including those taken in excess of the required frequency) must be taken at locations

  that represent the maximum residence time of the water in the distribution system. The remaining samples must

  be taken at locations representative of at least average residence time in the distribution system.

\2\ Multiple wells drawing water from a single aquifer may be considered one treatment plant for determining the

  minimum number of samples required, with State approval in accordance with criteria developed under Sec.

  142.16(f)(5) of this chapter.



    (ii) Systems may reduce monitoring, except as otherwise provided,

in accordance with the following table:



[[Page 69469]]







                                 Reduced Monitoring Frequency for TTHM and HAA5

----------------------------------------------------------------------------------------------------------------

                                      You may reduce monitoring

         If you are a . . .            if you have monitored at                    To this level

                                     least one year and your . .

--------------------------------------------------.-------------------------------------------------------------

Subpart H system serving at least    TTHM annual average <ls-thn- One sample per treatment plant per quarter at

10,000 persons which has a source    eq>0.040 mg/L and HAA5       distribution system location reflecting

water annual average TOC level,      annual average <ls-thn-      maximum residence time.

before any treatment, <ls-thn-       eq>0.030 mg/L.

eq>4.0 mg/L.

Subpart H system serving from 500    TTHM annual average <ls-thn- One sample per treatment plant per year at

to 9,999 persons which has a         eq>0.040 mg/L and HAA5       distribution system location reflecting

source water annual average TOC      annual average <ls-thn-      maximum residence time during month of

level, before any treatment, <ls-    eq>0.030 mg/L.               warmest water temperature. NOTE: Any Subpart

thn-eq>4.0 mg/L.                                                  H system serving fewer than 500 persons may

                                                                   not reduce its monitoring to less than one

                                                                   sample per treatment plant per year.

System using only ground water not   TTHM annual average <ls-thn- One sample per treatment plant per year at

under direct influence of surface    eq>0.040 mg/L and HAA5       distribution system location reflecting

water using chemical disinfectant    annual average <ls-thn-      maximum residence time during month of

and serving at least 10,000          eq>0.030 mg/L.               warmest water temperature

persons.

System using only ground water not   TTHM annual average <ls-thn- One sample per treatment plant per three year

under direct influence of surface    eq>0.040 mg/L and HAA5       monitoring cycle at distribution system

water using chemical disinfectant    annual average <ls-thn-      location reflecting maximum residence time

and serving fewer than 10,000        eq>0.030 mg/L for two        during month of warmest water temperature,

persons.                             consecutive years OR TTHM    with the three-year cycle beginning on

                                      annual average <ls-thn-      January 1 following quarter in which system

                                      eq>0.020 mg/L and HAA5       qualifies for reduced monitoring.

                                      annual average <ls-thn-

                                      eq>0.015 mg/L for one year.

----------------------------------------------------------------------------------------------------------------



    (iii) Systems on a reduced monitoring schedule may remain on that

reduced schedule as long as the average of all samples taken in the

year (for systems which must monitor quarterly) or the result of the

sample (for systems which must monitor no more frequently than

annually) is no more than 0.060 mg/L and 0.045 mg/L for TTHMs and HAA5,

respectively. Systems that do not meet these levels must resume

monitoring at the frequency identified in paragraph (b)(1)(i) of this

section in the quarter immediately following the quarter in which the

system exceeds 0.060 mg/L and 0.045 mg/L for TTHMs and HAA5,

respectively.

    (iv) The State may return a system to routine monitoring at the

State's discretion.

    (2) Chlorite. Community and nontransient noncommunity water systems

using chlorine dioxide, for disinfection or oxidation, must conduct

monitoring for chlorite.

    (i) Routine monitoring. (A) Daily monitoring. Systems must take

daily samples at the entrance to the distribution system. For any daily

sample that exceeds the chlorite MCL, the system must take additional

samples in the distribution system the following day at the locations

required by paragraph (b)(2)(ii) of this section, in addition to the

sample required at the entrance to the distribution system.

    (B) Monthly monitoring. Systems must take a three-sample set each

month in the distribution system. The system must take one sample at

each of the following locations: near the first customer, at a location

representative of average residence time, and at a location reflecting

maximum residence time in the distribution system. Any additional

routine sampling must be conducted in the same manner (as three-sample

sets, at the specified locations). The system may use the results of

additional monitoring conducted under paragraph (b)(2)(ii) of this

section to meet the requirement for monitoring in this paragraph.

    (ii) Additional monitoring. On each day following a routine sample

monitoring result that exceeds the chlorite MCL at the entrance to the

distribution system, the system is required to take three chlorite

distribution system samples at the following locations: as close to the

first customer as possible, in a location representative of average

residence time, and as close to the end of the distribution system as

possible (reflecting maximum residence time in the distribution

system).

    (iii) Reduced monitoring. (A) Chlorite monitoring at the entrance

to the distribution system required by paragraph (b)(2)(i)(A) of this

section may not be reduced.

    (B) Chlorite monitoring in the distribution system required by

paragraph (b)(2)(i)(B) of this section may be reduced to one three-

sample set per quarter after one year of monitoring where no individual

chlorite sample taken in the distribution system under paragraph

(b)(2)(i)(B) of this section has exceeded the chlorite MCL and the

system has not been required to conduct monitoring under paragraph

(b)(2)(ii) of this section. The system may remain on the reduced

monitoring schedule until either any of the three individual chlorite

samples taken quarterly in the distribution system under paragraph

(b)(2)(i)(B) of this section exceeds the chlorite MCL or the system is

required to conduct monitoring under paragraph (b)(2)(ii) of this

section, at which time the system must revert to routine monitoring.

    (3) Bromate. (i) Routine monitoring. Community and nontransient

noncommunity systems using ozone, for disinfection or oxidation, must

take one sample per month for each treatment plant in the system using

ozone. Systems must take samples monthly at the entrance to the

distribution system while the ozonation system is operating under

normal conditions.

    (ii) Reduced monitoring. Systems required to analyze for bromate

may reduce monitoring from monthly to once per quarter, if the system

demonstrates that the average source water bromide concentration is

less than 0.05 mg/L based upon representative monthly bromide

measurements for one year. The system may remain on reduced bromate

monitoring until the running annual average source water bromide

concentration, computed quarterly, is equal to or greater than 0.05 mg/

L based upon representative monthly measurements. If the running annual

average source water bromide concentration is <gr-thn-eq>0.05 mg/L, the

system must resume routine monitoring



[[Page 69470]]



required by paragraph (b)(3)(i) of this section.

    (c) Monitoring requirements for disinfectant residuals. (1)

Chlorine and chloramines. (i) Routine monitoring. Systems must measure

the residual disinfectant level at the same points in the distribution

system and at the same time as total coliforms are sampled, as

specified in Sec. 141.21. Subpart H systems may use the results of

residual disinfectant concentration sampling conducted under

Sec. 141.74(b)(6)(i) for unfiltered systems or Sec. 141.74(c)(3)(i) for

systems which filter, in lieu of taking separate samples.

    (ii) Reduced monitoring. Monitoring may not be reduced.

    (2) Chlorine dioxide. (i) Routine monitoring. Community,

nontransient noncommunity, and transient noncommunity water systems

that use chlorine dioxide for disinfection or oxidation must take daily

samples at the entrance to the distribution system. For any daily

sample that exceeds the MRDL, the system must take samples in the

distribution system the following day at the locations required by

paragraph (c)(2)(ii) of this section, in addition to the sample

required at the entrance to the distribution system.

    (ii) Additional monitoring. On each day following a routine sample

monitoring result that exceeds the MRDL, the system is required to take

three chlorine dioxide distribution system samples. If chlorine dioxide

or chloramines are used to maintain a disinfectant residual in the

distribution system, or if chlorine is used to maintain a disinfectant

residual in the distribution system and there are no disinfection

addition points after the entrance to the distribution system (i.e., no

booster chlorination), the system must take three samples as close to

the first customer as possible, at intervals of at least six hours. If

chlorine is used to maintain a disinfectant residual in the

distribution system and there are one or more disinfection addition

points after the entrance to the distribution system (i.e., booster

chlorination), the system must take one sample at each of the following

locations: as close to the first customer as possible, in a location

representative of average residence time, and as close to the end of

the distribution system as possible (reflecting maximum residence time

in the distribution system).

    (iii) Reduced monitoring. Chlorine dioxide monitoring may not be

reduced.

    (d) Monitoring requirements for disinfection byproduct precursors

(DBPP). (1) Routine monitoring. Subpart H systems which use

conventional filtration treatment (as defined in Sec. 141.2) must

monitor each treatment plant for TOC no later than the point of

combined filter effluent turbidity monitoring and representative of the

treated water. All systems required to monitor under this paragraph

(d)(1) must also monitor for TOC in the source water prior to any

treatment at the same time as monitoring for TOC in the treated water.

These samples (source water and treated water) are referred to as

paired samples. At the same time as the source water sample is taken,

all systems must monitor for alkalinity in the source water prior to

any treatment. Systems must take one paired sample and one source water

alkalinity sample per month per plant at a time representative of

normal operating conditions and influent water quality.

    (2) Reduced monitoring. Subpart H systems with an average treated

water TOC of less than 2.0 mg/L for two consecutive years, or less than

1.0 mg/L for one year, may reduce monitoring for both TOC and

alkalinity to one paired sample and one source water alkalinity sample

per plant per quarter. The system must revert to routine monitoring in

the month following the quarter when the annual average treated water

TOC <gr-thn-eq>2.0 mg/L.

    (e) Bromide. Systems required to analyze for bromate may reduce

bromate monitoring from monthly to once per quarter, if the system

demonstrates that the average source water bromide concentration is

less than 0.05 mg/L based upon representative monthly measurements for

one year. The system must continue bromide monitoring to remain on

reduced bromate monitoring.

    (f) Monitoring plans. Each system required to monitor under this

subpart must develop and implement a monitoring plan. The system must

maintain the plan and make it available for inspection by the State and

the general public no later than 30 days following the applicable

compliance dates in Sec. 141.130(b). All Subpart H systems serving more

than 3300 people must submit a copy of the monitoring plan to the State

no later than the date of the first report required under Sec. 141.134.

The State may also require the plan to be submitted by any other

system. After review, the State may require changes in any plan

elements. The plan must include at least the following elements.

    (1) Specific locations and schedules for collecting samples for any

parameters included in this subpart.

    (2) How the system will calculate compliance with MCLs, MRDLs, and

treatment techniques.

    (3) If approved for monitoring as a consecutive system, or if

providing water to a consecutive system, under the provisions of

Sec. 141.29, the sampling plan must reflect the entire distribution

system.





Sec. 141.133  Compliance requirements.



    (a) General requirements. (1) Where compliance is based on a

running annual average of monthly or quarterly samples or averages and

the system's failure to monitor for TTHM, HAA5, or bromate, this

failure to monitor will be treated as a monitoring violation for the

entire period covered by the annual average. Where compliance is based

on a running annual average of monthly or quarterly samples or averages

and the system's failure to monitor makes it impossible to determine

compliance with MRDLs for chlorine and chloramines, this failure to

monitor will be treated as a monitoring violation for the entire period

covered by the annual average.

    (2) All samples taken and analyzed under the provisions of this

subpart must be included in determining compliance, even if that number

is greater than the minimum required.

    (3) If, during the first year of monitoring under Sec. 141.132, any

individual quarter's average will cause the running annual average of

that system to exceed the MCL, the system is out of compliance at the

end of that quarter.

    (b) Disinfection byproducts. (1) TTHMs and HAA5. (i) For systems

monitoring quarterly, compliance with MCLs in Sec. 141.64 must be based

on a running annual arithmetic average, computed quarterly, of

quarterly arithmetic averages of all samples collected by the system as

prescribed by Sec. 141.132(b)(1). If the running annual arithmetic

average of quarterly averages covering any consecutive four-quarter

period exceeds the MCL, the system is in violation of the MCL and must

notify the public pursuant to Sec. 141.32, in addition to reporting to

the State pursuant to Sec. 141.134. If a PWS fails to complete four

consecutive quarters' monitoring, compliance with the MCL for the last

four-quarter compliance period must be based on an average of the

available data.

    (ii) For systems monitoring less frequently than quarterly,

compliance must be based on an average of samples taken that year under

the provisions of Sec. 141.132(b)(1). If the average of these samples

exceeds the MCL, the system must increase monitoring to once per

quarter per treatment plant.

    (iii) Systems on a reduced monitoring schedule whose annual average

exceeds the MCL will revert to routine monitoring immediately. These

systems



[[Page 69471]]



will not be considered in violation of the MCL until they have

completed one year of routine monitoring.

    (2). Bromate. Compliance must be based on a running annual

arithmetic average, computed quarterly, of monthly samples (or, for

months in which the system takes more than one sample, the average of

all samples taken during the month) collected by the system as

prescribed by Sec. 141.132(b)(3). If the average of samples covering

any consecutive four-quarter period exceeds the MCL, the system is in

violation of the MCL and must notify the public pursuant to

Sec. 141.32, in addition to reporting to the State pursuant to

Sec. 141.134. If a PWS fails to complete 12 consecutive months'

monitoring, compliance with the MCL for the last four-quarter

compliance period must be based on an average of the available data.

    (3) Chlorite. Compliance must be based on an arithmetic average of

each three sample set taken in the distribution system as prescribed by

Sec. 141.132(b)(2)(i)(B) and Sec. 141.132(b)(2)(ii). If the arithmetic

average of any three sample set exceeds the MCL, the system is in

violation of the MCL and must notify the public pursuant to

Sec. 141.32, in addition to reporting to the State pursuant to

Sec. 141.134.

    (c) Disinfectant residuals. (1) Chlorine and chloramines. (i)

Compliance must be based on a running annual arithmetic average,

computed quarterly, of monthly averages of all samples collected by the

system under Sec. 141.132(c)(1). If the average of quarterly averages

covering any consecutive four-quarter period exceeds the MRDL, the

system is in violation of the MRDL and must notify the public pursuant

to Sec. 141.32, in addition to reporting to the State pursuant to

Sec. 141.134.

    (ii) In cases where systems switch between the use of chlorine and

chloramines for residual disinfection during the year, compliance must

be determined by including together all monitoring results of both

chlorine and chloramines in calculating compliance. Reports submitted

pursuant to Sec. 141.134 must clearly indicate which residual

disinfectant was analyzed for each sample.

    (2) Chlorine dioxide. (i) Acute violations. Compliance must be

based on consecutive daily samples collected by the system under

Sec. 141.132(c)(2). If any daily sample taken at the entrance to the

distribution system exceeds the MRDL, and on the following day one (or

more) of the three samples taken in the distribution system exceed the

MRDL, the system is in violation of the MRDL and must take immediate

corrective action to lower the level of chlorine dioxide below the MRDL

and must notify the public pursuant to the procedures for acute health

risks in Sec. 141.32(a)(1)(iii)(E). Failure to take samples in the

distribution system the day following an exceedance of the chlorine

dioxide MRDL at the entrance to the distribution system will also be

considered an MRDL violation and the system must notify the public of

the violation in accordance with the provisions for acute violations

under Sec. 141.32(a)(1)(iii)(E).

    (ii) Nonacute violations. Compliance must be based on consecutive

daily samples collected by the system under Sec. 141.132(c)(2). If any

two consecutive daily samples taken at the entrance to the distribution

system exceed the MRDL and all distribution system samples taken are

below the MRDL, the system is in violation of the MRDL and must take

corrective action to lower the level of chlorine dioxide below the MRDL

at the point of sampling and will notify the public pursuant to the

procedures for nonacute health risks in Sec. 141.32(e)(78). Failure to

monitor at the entrance to the distribution system the day following an

exceedance of the chlorine dioxide MRDL at the entrance to the

distribution system is also an MRDL violation and the system must

notify the public of the violation in accordance with the provisions

for nonacute violations under Sec. 141.32(e)(78).

    (d) Disinfection byproduct precursors (DBPP). Compliance must be

determined as specified by Sec. 141.135(b). Systems may begin

monitoring to determine whether Step 1 TOC removals can be met 12

months prior to the compliance date for the system. This monitoring is

not required and failure to monitor during this period is not a

violation. However, any system that does not monitor during this

period, and then determines in the first 12 months after the compliance

date that it is not able to meet the Step 1 requirements in

Sec. 141.135(b)(2) and must therefore apply for alternate minimum TOC

removal (Step 2) requirements, is not eligible for retroactive approval

of alternate minimum TOC removal (Step 2) requirements as allowed

pursuant to Sec. 141.135(b)(3) and is in violation. Systems may apply

for alternate minimum TOC removal (Step 2) requirements any time after

the compliance date.





Sec. 141.134  Reporting and recordkeeping requirements.



    (a) Systems required to sample quarterly or more frequently must

report to the State within 10 days after the end of each quarter in

which samples were collected, notwithstanding the provisions of

Sec. 141.31. Systems required to sample less frequently than quarterly

must report to the State within 10 days after the end of each

monitoring period in which samples were collected.

    (b) Disinfection byproducts. Systems must report the information

specified in the following table:



------------------------------------------------------------------------

            If you are a...                   You must report...\1\

------------------------------------------------------------------------

System monitoring for TTHM and HAA5      (1) The number of samples taken

under the requirements of Secs.          during the last quarter.

141.132(b) on a quarterly or more

frequent basis.

                                         (2) The location, date, and

                                          result of each sample taken

                                          during the last quarter.

                                         (3) The arithmetic average of

                                          all samples taken in the last

                                          quarter.

                                         (4) The annual arithmetic

                                          average of the quarterly

                                          arithmetic averages of this

                                          section for the last four

                                          quarters.

                                         (5) Whether the MCL was

                                          exceeded.

System monitoring for TTHMs and HAA5     (1) The number of samples taken

under the requirements of Secs.          during the last year.

141.132(b) less frequently than

quarterly (but at least annually).

                                         (2) The location, date, and

                                          result of each sample taken

                                          during the last quarter.

                                         (3) The arithmetic average of

                                          all samples taken over the

                                          last year.

                                         (4) Whether the MCL was

                                          exceeded.

System monitoring for TTHMs and HAA5     (1) The location, date, and

under the requirements of Sec.           result of the last sample

141.132(b) less frequently than          taken.

annually.

                                         (2) Whether the MCL was

                                          exceeded.



[[Page 69472]]





System monitoring for chlorite under     (1) The number of samples taken

the requirements of Sec.  141.132(b).    each month for the last 3

                                          months.

                                         (2) The location, date, and

                                          result of each sample taken

                                          during the last quarter.

                                         (3) For each month in the

                                          reporting period, the

                                          arithmetic average of all

                                          samples taken in the month.

                                         (4) Whether the MCL was

                                          exceeded, and in which month

                                          it was exceeded.

System monitoring for bromate under the  (1) The number of samples taken

requirements of Sec.  141.132(b).        during the last quarter.

                                         (2) The location, date, and

                                          result of each sample taken

                                          during the last quarter.

                                         (3) The arithmetic average of

                                          the monthly arithmetic

                                          averages of all samples taken

                                          in the last year.

                                         (4) Whether the MCL was

                                          exceeded.

------------------------------------------------------------------------



    (c) Disinfectants. Systems must report the information specified in

the following table:



------------------------------------------------------------------------

            If you are a...                   You must report...\1\

------------------------------------------------------------------------

System monitoring for chlorine or        (1) The number of samples taken

chloramines under the requirements of    during each month of the last

Sec.  141.132(c).                        quarter.

                                         (2) The monthly arithmetic

                                          average of all samples taken

                                          in each month for the last 12

                                          months.

                                         (3) The arithmetic average of

                                          all monthly averages for the

                                          last 12 months.

                                         (4) Whether the MRDL was

                                          exceeded.

System monitoring for chlorine dioxide   (1) The dates, results, and

under the requirements of Sec.           locations of samples taken

141.132(c).                              during the last quarter.

                                         (2) Whether the MRDL was

                                          exceeded.

                                         (3) Whether the MRDL was

                                          exceeded in any two

                                          consecutive daily samples and

                                          whether the resulting

                                          violation was acute or

                                          nonacute.

------------------------------------------------------------------------

\1\ The State may choose to perform calculations and determine whether

  the MRDL was exceeded, in lieu of having the system report that

  information.



    (d) Disinfection byproduct precursors and enhanced coagulation or

enhanced softening. Systems must report the information specified in

the following table:



------------------------------------------------------------------------

           If you are a . . .                You must report . . .\1\

------------------------------------------------------------------------

System monitoring monthly or quarterly   (1) The number of paired

for TOC under the requirements of Sec.   (source water and treated

  141.132(d) and required to meet the     water, prior to continuous

enhanced coagulation or enhanced         disinfection) samples taken

softening requirements in Sec.           during the last quarter.

141.135(b)(2) or (3).

                                         (2) The location, date, and

                                          result of each paired sample

                                          and associated alkalinity

                                          taken during the last quarter.

                                         (3) For each month in the

                                          reporting period that paired

                                          samples were taken, the

                                          arithmetic average of the

                                          percent reduction of TOC for

                                          each paired sample and the

                                          required TOC percent removal.

                                         (4) Calculations for

                                          determining compliance with

                                          the TOC percent removal

                                          requirements, as provided in

                                          Sec.  141.135(c)(1).

                                         (5) Whether the system is in

                                          compliance with the enhanced

                                          coagulation or enhanced

                                          softening percent removal

                                          requirements in Sec.

                                          141.135(b) for the last four

                                          quarters.

System monitoring monthly or quarterly   (1) The alternative compliance

for TOC under the requirements of Sec.   criterion that the system is

  141.132(d) and meeting one or more of   using.

the alternative compliance criteria in

Sec.  141.135(a)(2) or (3).

                                         (2) The number of paired

                                          samples taken during the last

                                          quarter.

                                         (3) The location, date, and

                                          result of each paired sample

                                          and associated alkalinity

                                          taken during the last quarter.

                                         (4) The running annual

                                          arithmetic average based on

                                          monthly averages (or quarterly

                                          samples) of source water TOC

                                          for systems meeting a

                                          criterion in Secs.

                                          141.135(a)(2)(i) or (iii) or

                                          of treated water TOC for

                                          systems meeting the criterion

                                          in Sec.  141.135(a)(2)(ii).



[[Page 69473]]





                                         (5) The running annual

                                          arithmetic average based on

                                          monthly averages (or quarterly

                                          samples) of source water SUVA

                                          for systems meeting the

                                          criterion in Sec.

                                          141.135(a)(2)(v) or of treated

                                          water SUVA for systems meeting

                                          the criterion in Sec.

                                          141.135(a)(2)(vi).

                                         (6) The running annual average

                                          of source water alkalinity for

                                          systems meeting the criterion

                                          in Sec.  141.135(a)(2)(iii)

                                          and of treated water

                                          alkalinity for systems meeting

                                          the criterion in Sec.

                                          141.135(a)(3)(i).

                                         (7) The running annual average

                                          for both TTHM and HAA5 for

                                          systems meeting the criterion

                                          in Sec.  141.135(a)(2)(iii) or

                                          (iv).

                                         (8) The running annual average

                                          of the amount of magnesium

                                          hardness removal (as CaCO<INF>3, in

                                          mg/L) for systems meeting the

                                          criterion in Sec.

                                          141.135(a)(3)(ii).

                                         (9) Whether the system is in

                                          compliance with the particular

                                          alternative compliance

                                          criterion in Sec.

                                          141.135(a)(2) or (3).

------------------------------------------------------------------------

\1\ The State may choose to perform calculations and determine whether

  the treatment technique was met, in lieu of having the system report

  that information.



Sec. 141.135  Treatment technique for control of disinfection byproduct

(DBP) precursors.



    (a) Applicability. (1) Subpart H systems using conventional

filtration treatment (as defined in Sec. 141.2 ) must operate with

enhanced coagulation or enhanced softening to achieve the TOC percent

removal levels specified in paragraph (b) of this section unless the

system meets at least one of the alternative compliance criteria listed

in paragraph (a)(2) or (a)(3) of this section.

    (2) Alternative compliance criteria for enhanced coagulation and

enhanced softening systems. Subpart H systems using conventional

filtration treatment may use the alternative compliance criteria in

paragraphs (a)(2)(i) through (vi) of this section to comply with this

section in lieu of complying with paragraph (b) of this section.

Systems must still comply with monitoring requirements in

Sec. 141.132(d).

    (i) The system's source water TOC level, measured according to

Sec. 141.131(d)(3), is less than 2.0 mg/L, calculated quarterly as a

running annual average.

    (ii) The system's treated water TOC level, measured according to

Sec. 141.131(d)(3), is less than 2.0 mg/L, calculated quarterly as a

running annual average.

    (iii) The system's source water TOC level, measured as required by

Sec. 141.131(d)(3), is less than 4.0 mg/L, calculated quarterly as a

running annual average; the source water alkalinity, measured according

to Sec. 141.131(d)(1), is greater than 60 mg/L (as CaCO<INF>3</INF>),

calculated quarterly as a running annual average; and either the TTHM

and HAA5 running annual averages are no greater than 0.040 mg/L and

0.030 mg/L, respectively; or prior to the effective date for compliance

in Sec. 141.130(b), the system has made a clear and irrevocable

financial commitment not later than the effective date for compliance

in Sec. 141.130(b) to use of technologies that will limit the levels of

TTHMs and HAA5 to no more than 0.040 mg/L and 0.030 mg/L, respectively.

Systems must submit evidence of a clear and irrevocable financial

commitment, in addition to a schedule containing milestones and

periodic progress reports for installation and operation of appropriate

technologies, to the State for approval not later than the effective

date for compliance in Sec. 141.130(b). These technologies must be

installed and operating not later than June 16, 2005. Failure to

install and operate these technologies by the date in the approved

schedule will constitute a violation of National Primary Drinking Water

Regulations.

    (iv) The TTHM and HAA5 running annual averages are no greater than

0.040 mg/L and 0.030 mg/L, respectively, and the system uses only

chlorine for primary disinfection and maintenance of a residual in the

distribution system.

    (v) The system's source water SUVA, prior to any treatment and

measured monthly according to Sec. 141.131(d)(4), is less than or equal

to 2.0 L/mg-m, calculated quarterly as a running annual average.

    (vi) The system's finished water SUVA, measured monthly according

to Sec. 141.131(d)(4), is less than or equal to 2.0 L/mg-m, calculated

quarterly as a running annual average.

    (3) Additional alternative compliance criteria for softening

systems. Systems practicing enhanced softening that cannot achieve the

TOC removals required by paragraph (b)(2) of this section may use the

alternative compliance criteria in paragraphs (a)(3)(i) and (ii) of

this section in lieu of complying with paragraph (b) of this section.

Systems must still comply with monitoring requirements in

Sec. 141.132(d).

    (i) Softening that results in lowering the treated water alkalinity

to less than 60 mg/L (as CaCO<INF>3</INF>), measured monthly according

to Sec. 141.131(d)(1) and calculated quarterly as a running annual

average.

    (ii) Softening that results in removing at least 10 mg/L of

magnesium hardness (as CaCO<INF>3</INF>), measured monthly and

calculated quarterly as an annual running average.

    (b) Enhanced coagulation and enhanced softening performance

requirements. (1) Systems must achieve the percent reduction of TOC

specified in paragraph (b)(2) of this section between the source water

and the combined filter effluent, unless the State approves a system's

request for alternate minimum TOC removal (Step 2) requirements under

paragraph (b)(3) of this section.

    (2) Required Step 1 TOC reductions, indicated in the following

table, are based upon specified source water parameters measured in

accordance with Sec. 141.131(d). Systems practicing softening are

required to meet the Step 1 TOC reductions in the far-right column

(Source water alkalinity >120 mg/L) for the specified source water TOC:



[[Page 69474]]







    Step 1 Required Removal of TOC by Enhanced Coagulation and Enhanced Softening for Subpart H Systems Using

                                          Conventional Treatment <SUP>1,\\\<SUP>2

----------------------------------------------------------------------------------------------------------------

                                                                     Source-water alkalinity, mg/L as CaCO<INF>3

                                                              --------------------------------------------------

                    Source-water TOC, mg/L                                     <ls-thn-eq>60-120     >120 \3\

                                                               0-60 (percent)      (percent)         (percent)

----------------------------------------------------------------------------------------------------------------

>2.0-4.0.....................................................            35.0              25.0             15.0

>4.0-8.0.....................................................            45.0              35.0             25.0

>8.0.........................................................            50.0              40.0            30.0

----------------------------------------------------------------------------------------------------------------

\1\ Systems meeting at least one of the conditions in paragraph (a)(2)(i)-(vi) of this section are not required

  to operate with enhanced coagulation.

\2\ Softening systems meeting one of the alternative compliance criteria in paragraph (a)(3) of this section are

  not required to operate with enhanced softening.

\3\ Systems practicing softening must meet the TOC removal requirements in this column.



    (3) Subpart H conventional treatment systems that cannot achieve

the Step 1 TOC removals required by paragraph (b)(2) of this section

due to water quality parameters or operational constraints must apply

to the State, within three months of failure to achieve the TOC

removals required by paragraph (b)(2) of this section, for approval of

alternative minimum TOC (Step 2) removal requirements submitted by the

system. If the State approves the alternative minimum TOC removal (Step

2) requirements, the State may make those requirements retroactive for

the purposes of determining compliance. Until the State approves the

alternate minimum TOC removal (Step 2) requirements, the system must

meet the Step 1 TOC removals contained in paragraph (b)(2) of this

section.

    (4) Alternate minimum TOC removal (Step 2) requirements.

Applications made to the State by enhanced coagulation systems for

approval of alternative minimum TOC removal (Step 2) requirements under

paragraph (b)(3) of this section must include, as a minimum, results of

bench- or pilot-scale testing conducted under paragraph (b)(4)(i) of

this section and used to determine the alternate enhanced coagulation

level.

    (i) Alternate enhanced coagulation level is defined as coagulation

at a coagulant dose and pH as determined by the method described in

paragraphs (b)(4)(i) through (v) of this section such that an

incremental addition of 10 mg/L of alum (as aluminum) (or equivalent

amount of ferric salt) results in a TOC removal of <ls-thn-eq> 0.3 mg/

L. The percent removal of TOC at this point on the ``TOC removal versus

coagulant dose'' curve is then defined as the minimum TOC removal

required for the system. Once approved by the State, this minimum

requirement supersedes the minimum TOC removal required by the table in

paragraph (b)(2) of this section. This requirement will be effective

until such time as the State approves a new value based on the results

of a new bench- and pilot-scale test. Failure to achieve State-set

alternative minimum TOC removal levels is a violation of National

Primary Drinking Water Regulations.

    (ii) Bench- or pilot-scale testing of enhanced coagulation must be

conducted by using representative water samples and adding 10 mg/L

increments of alum (as aluminum) (or equivalent amounts of ferric salt)

until the pH is reduced to a level less than or equal to the enhanced

coagulation Step 2 target pH shown in the following table:



                  Enhanced Coagulation Step 2 target pH

------------------------------------------------------------------------

                 Alkalinity (mg/L as CaCO<INF>3)                   Target pH

------------------------------------------------------------------------

0-60.......................................................          5.5

>60-120....................................................          6.3

>120-240...................................................          7.0

>240.......................................................          7.5

------------------------------------------------------------------------



    (iii) For waters with alkalinities of less than 60 mg/L for which

addition of small amounts of alum or equivalent addition of iron

coagulant drives the pH below 5.5 before significant TOC removal

occurs, the system must add necessary chemicals to maintain the pH

between 5.3 and 5.7 in samples until the TOC removal of 0.3 mg/L per 10

mg/L alum added (as aluminum) (or equivalant addition of iron

coagulant) is reached.

    (iv) The system may operate at any coagulant dose or pH necessary

(consistent with other NPDWRs) to achieve the minimum TOC percent

removal approved under paragraph (b)(3) of this section.

    (v) If the TOC removal is consistently less than 0.3 mg/L of TOC

per 10 mg/L of incremental alum dose (as aluminum) at all dosages of

alum (or equivalant addition of iron coagulant), the water is deemed to

contain TOC not amenable to enhanced coagulation. The system may then

apply to the State for a waiver of enhanced coagulation requirements.

    (c) Compliance calculations. (1) Subpart H systems other than those

identified in paragraph (a)(2) or (a)(3) of this section must comply

with requirements contained in paragraph (b)(2) of this section.

Systems must calculate compliance quarterly, beginning after the system

has collected 12 months of data, by determining an annual average using

the following method:

    (i) Determine actual monthly TOC percent removal, equal to:



(1--(treated water TOC/source water TOC))  x  100



    (ii) Determine the required monthly TOC percent removal (from

either the table in paragraph (b)(2) of this section or from paragraph

(b)(3) of this section).

    (iii) Divide the value in paragraph (c)(1)(i) of this section by

the value in paragraph (c)(1)(ii) of this section.

    (iv) Add together the results of paragraph (c)(1)(iii) of this

section for the last 12 months and divide by 12.

    (v) If the value calculated in paragraph (c)(1)(iv) of this section

is less than 1.00, the system is not in compliance with the TOC percent

removal requirements.

    (2) Systems may use the provisions in paragraphs (c)(2)(i) through

(v) of this section in lieu of the calculations in paragraph (c)(1)(i)

through (v) of this section to determine compliance with TOC percent

removal requirements.

    (i) In any month that the system's treated or source water TOC

level, measured according to Sec. 141.131(d)(3), is less than 2.0 mg/L,

the system may assign a monthly value of 1.0 (in lieu of the value

calculated in paragraph (c)(1)(iii) of this section) when calculating

compliance under the provisions of paragraph (c)(1) of this section.

    (ii) In any month that a system practicing softening removes at

least 10 mg/L of magnesium hardness (as CaCO<INF>3</INF>), the system

may assign a



[[Page 69475]]



monthly value of 1.0 (in lieu of the value calculated in paragraph

(c)(1)(iii) of this section) when calculating compliance under the

provisions of paragraph (c)(1) of this section.

    (iii) In any month that the system's source water SUVA, prior to

any treatment and measured according to Sec. 141.131(d)(4), is

<ls-thn-eq>2.0 L/mg-m, the system may assign a monthly value of 1.0 (in

lieu of the value calculated in paragraph (c)(1)(iii) of this section)

when calculating compliance under the provisions of paragraph (c)(1) of

this section.

    (iv) In any month that the system's finished water SUVA, measured

according to Sec. 141.131(d)(4), is <ls-thn-eq>2.0 L/mg-m, the system

may assign a monthly value of 1.0 (in lieu of the value calculated in

paragraph (c)(1)(iii) of this section) when calculating compliance

under the provisions of paragraph (c)(1) of this section.

    (v) In any month that a system practicing enhanced softening lowers

alkalinity below 60 mg/L (as CaCO<INF>3</INF>), the system may assign a

monthly value of 1.0 (in lieu of the value calculated in paragraph

(c)(1)(iii) of this section) when calculating compliance under the

provisions of paragraph (c)(1) of this section.

    (3) Subpart H systems using conventional treatment may also comply

with the requirements of this section by meeting the criteria in

paragraph (a)(2) or (3) of this section.

    (d) Treatment technique requirements for DBP precursors. The

Administrator identifies the following as treatment techniques to

control the level of disinfection byproduct precursors in drinking

water treatment and distribution systems: For Subpart H systems using

conventional treatment, enhanced coagulation or enhanced softening.

    11. Section 141.154 is amended by adding paragraph (e) to read as

follows:





Sec. 141.154  Required additional health information.



* * * * *

    (e) Community water systems that detect TTHM above 0.080 mg/l, but

below the MCL in Sec. 141.12, as an annual average, monitored and

calculated under the provisions of Sec. 141.30, must include health

effects language prescribed by paragraph (73) of appendix C to subpart

O.



PART 142--NATIONAL PRIMARY DRINKING WATER REGULATIONS

IMPLEMENTATION



    12. The authority citation for part 142 continues to read as

follows:



    Authority: 42 U.S.C. 300f, 300g-1, 300g-2 300g-3, 300g-4, 300g-

5, 300g-6, 300j-4, 300j-9, and 300j-11.



    13. Section 142.14 is amended by adding new paragraphs (d)(12),

(d)(13), (d)(14), (d)(15), and (d)(16) to read as follows.





Sec. 142.14  Records kept by States.



* * * * *

    (d) * * *

    (12) Records of the currently applicable or most recent State

determinations, including all supporting information and an explanation

of the technical basis for each decision, made under the following

provisions of 40 CFR part 141, subpart L for the control of

disinfectants and disinfection byproducts. These records must also

include interim measures toward installation.

    (i) States must keep records of systems that are installing GAC or

membrane technology in accordance with Sec. 141.64(b)(2) of this

chapter. These records must include the date by which the system is

required to have completed installation.

    (ii) States must keep records of systems that are required, by the

State, to meet alternative minimum TOC removal requirements or for whom

the State has determined that the source water is not amenable to

enhanced coagulation in accordance with Sec. 141.135(b)(3) and (4) of

this chapter, respectively. These records must include the alternative

limits and rationale for establishing the alternative limits.

    (iii) States must keep records of subpart H systems using

conventional treatment meeting any of the alternative compliance

criteria in Sec. 141.135(a)(2) or (3) of this chapter.

    (iv) States must keep a register of qualified operators that have

met the State requirements developed under Sec. 142.16(f)(2).

    (13) Records of systems with multiple wells considered to be one

treatment plant in accordance with Sec. 141.132(a)(2) of this chapter

and Sec. 142.16(f)(5).

    (14) Monitoring plans for subpart H systems serving more than 3,300

persons in accordance with Sec. 141.132(f) of this chapter.

    (15) List of laboratories approved for analyses in accordance with

Sec. 141.131(b) of this chapter.

    (16) List of systems required to monitor for disinfectants and

disinfection byproducts in accordance with part 141, subpart L of this

chapter. The list must indicate what disinfectants and DBPs, other than

chlorine, TTHM, and HAA5, if any, are measured.

* * * * *

    14. Section 142.16 is amended by adding paragraph (h) to read as

follows.





Sec. 142.16  Special primacy requirements.



* * * * *

    (h) Requirements for States to adopt 40 CFR part 141, subpart L. In

addition to the general primacy requirements elsewhere in this part,

including the requirement that State regulations be at least as

stringent as federal requirements, an application for approval of a

State program revision that adopts 40 CFR part 141, subpart L, must

contain a description of how the State will accomplish the following

program requirements:

    (1) Section 141.64(b)(2) of this chapter (interim treatment

requirements). Determine any interim treatment requirements for those

systems electing to install GAC or membrane filtration and granted

additional time to comply with Sec. 141.64 of this chapter.

    (2) Section 141.130(c) of this chapter (qualification of

operators). Qualify operators of public water systems subject to 40 CFR

part 141, subpart L. Qualification requirements established for

operators of systems subject to 40 CFR part 141, subpart H--Filtration

and Disinfection may be used in whole or in part to establish operator

qualification requirements for meeting 40 CFR part 141, subpart L

requirements if the State determines that the 40 CFR part 141, subpart

H requirements are appropriate and applicable for meeting subpart L

requirements.

    (3) Section 141.131(c)(2) of this chapter (DPD colorimetric test

kits). Approve DPD colorimetric test kits for free and total chlorine

measurements. State approval granted under Sec. 141.74(a)(2) of this

chapter for the use of DPD colorimetric test kits for free chlorine

testing is acceptable for the use of DPD test kits in measuring free

chlorine residuals as required in 40 CFR part 141, subpart L.

    (4) Sections 141.131(c)(3) and (d) of this chapter (State approval

of parties to conduct analyses). Approve parties to conduct pH,

bromide, alkalinity, and residual disinfectant concentration

measurements. The State's process for approving parties performing

water quality measurements for systems subject to 40 CFR part 141,

subpart H requirements in paragraph (b)(2)(i)(D) of this section may be

used for approving parties measuring water quality parameters for

systems subject to subpart L requirements, if the State determines the

process is appropriate and applicable.



[[Page 69476]]



    (5) Section 141.132(a)(2) of this chapter (multiple wells as a

single source). Define the criteria to use to determine if multiple

wells are being drawn from a single aquifer and therefore be considered

a single source for compliance with monitoring requirements.

    (6) Approve alternate minimum TOC removal (Step 2) requirements, as

allowed under the provisions of Sec. 141.135(b) of this chapter.



[FR Doc. 98-32887 Filed 12-15-98; 8:45 am]

BILLING CODE 6560-50-U

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