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Water: Sewage Sludge (Biosolids)

Report Summary and Findings

Summary: ISCORS Recommendations on Management of Radioactive Materials in Sewage Sludge and Ash at Publicly Owned Treatment Works (POTWs)

This guidance document has three major purposes:

  • to alert POTW operators to the possibility of radioactive materials concentrating in sewage sludge and incinerator ash;
  • to inform POTW operators how to determine if, indeed, there are elevated levels of radioactivity in their sludge and ash; and
  • to assist POTW operators in identifying actions for reducing potential radiation exposure from sludge and ash.

The overall conclusions of the nearly ten-year ISCORS effort to address the management of radioactive materials in sewage sludge and ash are:

  • The levels of radioactive materials founding sewage sludge and ash samples from most POTWs are generally low and the associated radiation exposure to workers and the general public is very low, and not likely to be of concern.
  • The estimated radiation doses to potentially exposed individuals are generally well below levels requiring radiation protection actions. For unique POTW worker and on-site resident scenarios, does exceeding protective standards could occur, primarily due to indoor radon generated as a decay product of NORM (e.g., 226Ra and 228Th). Such exposures can be significantly reduced through the use of readily available radon testing and mitigation technologies.
  • Where the estimated annual dose from all radionuclides exceeds 10 mrem yr-1, ISCORS recommends that the POTW operator consult with the state radiation protection regulatory agency. The 10 mrem yr-1 criterion is not a limit, does not include radon, and is not intended to suggest that higher dose levels are unacceptable.

The two reports, along with ISCORS' final survey report (issued in 2003), ISCORS Assessment of Radioactivity in Sewage Sludge: Radiological Survey Results and Analysis [ISCORS Technical Report 2003-02], are available on the ISCORS website at http://www.iscors.org/library.html  Exit EPA Disclaimer . Copies of the Federal Register Notice of Availability are available at http://edocket.access.gpo.gov/2005/pdf/E5-2073.pdf.

A limited number of copies of all three documents have been printed for distribution by NRC and EPA.

For additional information contact:
Robert Bastian
U.S. Environmental Protection Agency
Office of Wastewater Management
1200 Pennsylvania Ave., NW
Mail Code 4204M
Washington, D.C. 20460
phone: (202) 564-0653

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