Member Pipeline - Regulatory - Alert (RA 03-15)
To: Members & Affiliates, Biosolids Management Committee
From: National Office
Date: December 4, 2003
Subject: NRC AND EPA RELEASE RECOMMENDATIONS ON RADIOACTIVE MATERIALS IN BIOSOLIDS, AMSA SEEKS MEMBER COMMENTS
Reference: RA 03-15
Action Please By:
January 16, 2004
Printer friendly versionOn November 26, 2003, the U.S. Environmental Protection Agency (EPA or Agency) and the Nuclear Regulatory Commission (NRC), through the Interagency Steering Committee on Radiation Standards (ISCORS), announced the availability of three reports regarding radioactive materials in biosolids. The report containing recommendations to publicly owned treatment works (POTWs) very clearly concludes that, for most POTWs, exposure to radioactive materials in sewage sludge is not likely to be a concern for POTW workers or the general public (68 Fed. Reg. 66503). These documents give no indication that the NRC or EPA plan to take regulatory action, or place any new requirements on POTWs regarding radioactive materials in sewage sludge or incinerator ash. However, both agencies are recommending that POTWs assess whether there are sources present that could contribute to elevated levels of radioactive material in their system, plant or biosolids. If the level of radioactive material exceeds 10 mrem/year (a rem, or radiation equivalent man, is the conventional measurement unit for radiation dose), NRC and EPA recommend that POTWs consult the appropriate state authority for further guidance. These recommendations are discussed in greater detail below.
The first report, "ISCORS Assessment of Radioactivity in Sewage Sludge: Radiological Survey Results and Analysis," which summarizes the results of the 2000 ISCORS survey of 313 POTWs, was issued as a final document. The other two documents, "ISCORS Assessment of Radioactivity in Sewage Sludge: Modeling to Assess Radiation Doses" and "ISCORS Assessment of Radioactivity in Sewage Sludge: Recommendations on Management of Radioactive Materials in Sewage Sludge and Ash at Publicly Owned Treatment Works" (Recommendations) were released for public comment. ISCORS is accepting comments until February 6, 2004. AMSA will be developing comments on the documents and is seeking general member comment on the areas outlined below by January 16, 2004. The documents are available at http://www.iscors.org/library.htm.
Background
Sanitary sewer disposal of radioactive material became an issue
in the 1980s with the discovery of elevated levels of radioactive materials in
sewage sludge/incinerator ash at several POTWs. Although the NRC has not seen
any further problems since its regulations were revised in 1991, the NRC and EPA
have been working together since the early 1990s to gain a better understanding
of radioactivity-related issues. A 1994 General Accounting Office report,
Nuclear Regulation: Action Needed to Control Radioactive Contamination at Sewage
Treatment Plants, which found that of the more that 22,000 regulated users
of radioactive materials, about 9000 users have the potential to release
radioactive materials to sanitary sewer systems, precipitated more direct
action. EPA and the NRC conducted a survey in 1998 to collect information
concerning radioactive materials in sewage sludge and ash from POTWs. The
documents released on November 26 are the culmination of this cooperative
effort.
Summary of Documents
This section discusses the three released documents in more
detail. Of most importance for POTWs is the third document which spells out the
NRC and EPA recommendations for dealing with radioactive material in biosolids.
1. ISCORS Assessment of Radioactivity in Sewage Sludge: Survey Results and
Analysis
From 1998 to 2000, the Sewage Sludge Subcommittee of ISCORS conducted a survey,
taking sludge and ash samples from 313 POTWs in order to obtain national
estimates of radioactive materials found in sewage sludge and to possibly
support rulemakings by NRC and EPA. This final report provides the results and
analysis of that survey.
2. ISCORS Assessment of Radioactivity in Sewage Sludge: Modeling to Assess
Radiation Doses
Concurrent with the survey described above, ISCORS began to model the transport
of relevant radionuclides from sludge into the local environment. The modeling
first looked at the various ways that POTW workers or members of the public
could be exposed to sludge, then used an available model to generate sludge
concentration-to-dose conversion factors. This draft report provides the results
of the dose modeling effort, giving descriptions and justifications of the dose
assessment methodology.
The basic conclusions of the ISCORS survey and dose assessment, which ISCORS admits uses scenarios that are “somewhat conservative,” are as follows:
- None of the non-POTW scenarios shows a significant current widespread threat to public health.
- If agricultural land application is carried out for a long time into the future, then the potential exists for future radiation exposure primarily due to radon, if the land application site is converted to residential use.
- In specific cases of very high concentrations of radioactive materials (e.g., levels above the 95 percentile), there is the potential for localized radiation exposure.
- Within the POTW, little exposure is expected. Only when workers are in poorly ventilated areas with large quantities of sludge (e.g., for storage or loading) is there the potential for significant exposure, predominantly due to radon.
- Higher doses are generally attributable to the indoor radon pathway. Both for the Onsite Resident and the POTW Worker, exposures can be decreased significantly through the use of readily available radon testing and mitigation technologies.
3. ISCORS Assessment of Radioactivity in Sewage Sludge: Recommendations on
Management of Radioactive Materials in Sewage Sludge and Ash at Publicly Owned
Treatment Works
While EPA and the NRC generally conclude that radioactive materials in biosolids
pose little risk, they do recommend that each POTW assess its own system to
determine whether there are any sources that could contribute to elevated levels
of radioactive materials. This document was developed to aid POTWs in making
this assessment and in understanding the results. Of particular importance to
POTWs are Chapters 5-7. On page xix of the Executive Summary, a
flowchart provides a concise outline of the recommended process for dealing with
radioactive materials in sewage sludge and ash. Chapters 5 through 7 provide
further detail on this recommended process.
Specifically, Chapter 5 provides steps for POTWs to follow to determine if their plants may be receiving wastewater that contains radioactive materials or if there are other sources present that could contribute to elevated levels of radioactive materials at the plant (e.g., the plant may be located in an area prone to elevated levels of radon). The chapter also provides guidance on when sampling of sludge (and ash) or monitoring for radon may be necessary and how to develop a sampling plan. The document cautions POTWs to first consider what sources may be present and to seek the assistance of a radiation protection specialist before conducting an extensive sampling or monitoring program.
Chapter 6 details the process for evaluating sludge and ash sampling and monitoring results as well as determining whether any further action by the POTW operator is warranted. By using sludge and ash sampling results and the tables presented in Chapter 6, a POTW can calculate the annual dose from all radionuclides detected in its biosolids. This document states that there is no need for further action when the estimated dose is 10 mrem/year or less. The document goes out of its way to emphasize that these are recommendations and not requirements. As the report itself states:
“This conservative estimated dose (i.e., 10 mrem/year) is provided solely as a recommendation for when the POTW operator should seek further consultation. It is not to be interpreted as a requirement for taking other actions; the 10 mrem/year is not a limit, does not include radon, and is not intended to suggest that higher doses are unacceptable.”
Instead of including radon in the calculation of 10 mrem/year, EPA is recommending that POTWs test for the presence of radon gas, especially in enclosed areas where sludge is handled, and for action to be taken to reduce radon concentration levels if test results average 4 pCi/liter (picocurie/liter) or greater (a guideline level used for schools and homes).
Chapter 6 also notes that consultation with a state radiation protection regulatory agency (if estimated doses exceed 10 mrem/year) may result in one of several recommendations:
- No additional steps need be taken;
- Additional sludge or ash samples are needed;
- Additional indoor radon monitoring is needed;
- A site-specific evaluation or a monitoring program is needed;
- Possible changes in management practices that would reduce exposures should be evaluated;
- A professional radiation protection specialist or a health physicist should be contacted for assistance in designing a monitoring program or evaluating existing management practices;
- Another agency should be contacted for further guidance.
Chapter 7 provides guidance on what can be done to reduce radiation doses and radon levels, including contacting regulatory agencies for assistance, controlling sources, and reducing exposure to radioactivity from biosolids both at the plant and at land application sites.
While EPA and NRC did not enumerate specific issues for comment, AMSA encourages its members to review these documents, especially the Recommendations document, and provide the Association with any comments. Specifically, AMSA is interested in any concerns your utility may have with the 10 mrem/year threshold for radioactivity and the 4 pCi/liter concentration threshold for radon. Please direct any questions or comments to Chris Hornback, AMSA’s Director of Regulatory Affairs at 202/833-9106 or chornback@amsa-cleanwater.org.