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Water: Oil & Gas Extraction

Unconventional Extraction in the Oil and Gas Industry

Photo of a shale gas well pad

EPA is developing a proposed rule to amend the Effluent Limitations Guidelines (ELGs) for the Oil and Gas Extraction Category, (40 CFR Part 435). The proposed rule is scheduled for publication in 2014.

In the 2012 Preliminary ELG Plan, published on August 7, 2013, EPA announced that it is proposing to discontinue revisions to the Oil and Gas ELGs to regulate pollutant discharges from the coalbed methane extraction (CBM) industry. As the plan also indicates, EPA will continue developing revisions to the Onshore Oil and Gas ELGs (40 CFR Part 435, Subpart C) to provide additional controls on pollutant discharges from the unconventional oil and gas extraction industry. EPA continues to collect and analyze information and will examine a variety of options for these discharges.

  • Extraction Process
  • Wastewater Generated by Unconventional Extraction 
  • Current Federal Regulatory Framework 
  • Proposal to Delist Coalbed Methane Rulemaking 
  • Additional Resources 
  • Additional Information

Extraction Process

Recent advances in hydraulic fracturing and horizontal drilling have made extraction of oil and gas from unconventional resources more technologically and economically feasible than before. Hydraulic fracturing is used to extract oil and gas from highly impermeable rock formations, such as shale rock, by injecting large amounts of fracturing fluids at high pressures to create a network of fissures in the rock formations and providing the oil and/or gas a pathway to travel to the well for extraction. Geologic pressure within the impermeable shale formations force these fracturing fluids back to the surface (sometimes referred to as "flowback"), along with naturally occurring formation water. These wastewaters are collectively referred to as unconventional oil and gas extraction wastewaters, or produced water.

Coalbeds are another source of unconventional gas. This gas—CBM—is naturally created during the geologic process of converting plant material to coal (coalification). To extract the methane, CBM operators drill wells into coal seams and pump out ground water (produced water or CBM wastewater). Removing the ground water from the formation is necessary to produce CBM, as the water removal reduces the pressure and allows the methane to release from the coal to produce flowing natural gas.

Wastewater Generated by Unconventional Extraction

Produced water from unconventional oil and gas wells often contains high concentrations of total dissolved solids (salts). These wastewaters may also contain various organic chemicals, inorganic chemicals, metals, and naturally occurring radioactive materials (NORM). The quantity and quality of produced water varies from basin to basin, and over the lifetime of a well.

Current Federal Regulatory Framework

Direct discharges from unconventional oil and gas extraction are subject to NPDES permit regulations (40 CFR Parts 122 through 125). Indirect discharges to Publicly Owned Treatment Works (POTWs) are subject to the General Pretreatment Regulations (40 CFR Part 403).

NPDES permits must include technology based effluent limitations. For direct dischargers of unconventional oil and gas wastewaters from onshore oil and gas facilities – with the exception of coalbed methane – technology-based limitations are based on the Effluent Limitations Guidelines (ELGs) for the Oil and Gas Extraction Category (40 CFR Part 435). Permits for onshore oil and gas facilities must include the requirements in Part 435, including a ban on the discharge of pollutants, except for wastewater that is of good enough quality for use in agricultural and wildlife propagation for those onshore facilities located in the continental United States and west of the 98th meridian. Part 435 does not currently include categorical pretreatment standards for indirect discharges to POTWs for wells located onshore (i.e., PSES or PSNS).

Direct discharges from coalbed methane extraction from onshore oil and gas facilities are not currently subject to limitations under Part 435, as EPA did not consider such discharges in developing the onshore oil and gas ELG. NPDES permits for coalbed methane discharges are currently developed according to the best professional judgement (BPJ) of the permit authority, based on the factors specified in 40 CFR 125.3(c)(2). The BPJ-based requirements that have been applied to disposal of coalbed methane wastewater vary significantly from state to state, ranging from limitations on some conventional pollutants prior to discharge, to prohibition of direct discharges to waters of the U.S. (For more information on the BPJ permit process, see Chapter 5 of the NPDES Permit Writer's Manual).

Proposal to Delist Coalbed Methane Rulemaking

In 2010, EPA published a report on the coalbed methane extraction industry.  Since initiating the CBM rulemaking, EPA continued analyzing the information collected from the CBM industry and also collected and analyzed more current data. Some of EPA’s findings have changed since EPA selected this industry for the rulemaking. To update the public on technical aspects, EPA developed the Technical Development Document for the Coalbed Methane (CBM) Extraction Industry and Economic Analysis for Existing and New Projects in the Coalbed Methane Industry.  After reviewing financial data pertaining to this industry (including natural gas price projections from the U.S. Energy Information Administration), wastewater quality/quantity data and the cost of available wastewater treatment options, it appears that EPA may not be able to identify a wastewater treatment technology that would be economically achievable for this industrial subcategory. Although potential treatment technologies may exist, these technologies do not appear to be economically achievable due, in part, to the decrease in gas prices as a result of the recent boom in development of shale gas resources.

Therefore, the Agency is proposing to delist its CBM rulemaking from the ELG Plan.

Additional Resources

You will need Adobe Reader to view some of the files on this page. See EPA's PDF page to learn more.

Additional Information

To obtain more information on the rulemaking please contact Lisa Biddle, (biddle.lisa@epa.gov) at 202-566-0350.

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