Blending Policy to Help Plants Manage Wet Weather Flows

The U.S. Environmental Protection Agency (EPA) has released its proposed guidance on blending of partially treated stormwater and treated effluent...

Dec 1st, 2003

The U.S. Environmental Protection Agency (EPA) has released its proposed guidance on blending of partially treated stormwater and treated effluent, reaffirming the Agency's long-standing policy that blending is an acceptable method of addressing peak wet weather flows at publicly owned treatment works (POTWs).

G. Tracy Mehan, III, Assistant Administrator for Water, said, "This policy will provide a consistent set of principles to guide local sewage treatment facilities in managing wet-weather events. We are working with these facilities to prevent backups of sewage in homes and the environment while requiring all discharges to meet Clean Water Act permit limits."

The draft policy focuses on the practice of blending which occurs when large volumes of wastewater, caused by heavy rainfall or snowmelt, exceed the capacity of the secondary (biological) treatment units at a sewage treatment facility. During a storm, the incoming wastewater is treated by the primary units and then sent to the secondary treatment units. Amounts in excess of the capacity of the secondary units are diverted around and then later recombined or blended with the wastewater that has been treated by the secondary units. These blended flows are disinfected and discharged.

Larry Jaworski, President of the Water Environment Federation said, "The Water Environment Federation is pleased that EPA is providing national guidance on blending at municipal wastewater treatment plants during wet weather. Blending is a long-standing, sensible practice used to manage high flow events at wastewater treatment plants while maintaining compliance with NPDES permit limits. EPA's guidance will support local governments in planning and operating wastewater facilities which provide environmentally sound and cost effective treatment during a variety of conditions, leading to improvements in water quality."

This proposed policy will help to clarify the requirements of the Clean Water Act and applicable regulations on the practice of blending and requires that municipal sewage treatment facilities implement safeguards, including enhanced monitoring. The policy emphasizes the requirement that every sewage treatment facility in the United States must maintain compliance with the Clean Water Act. The policy also strongly encourages states that have not already done so to adopt EPA's 1986 water quality criteria for pathogens and to ensure that blending is addressed in the permitting process.

The public is invited to comment on the draft policy until Jan. 9, 2004. The draft policy and instructions for submitting comments are available at: http://www.epa.gov/npdes/blending.

EPA Will Not Regulate Dioxin in Sewage Sludge
EPA has made a final decision not to regulate dioxins in land-applied sewage sludge. After five years of study, including outside peer review, the agency has determined that dioxins from this source do not pose a significant risk to human health or the environment.

The most highly exposed people, theoretically, are those people who apply sewage sludge as a fertilizer to their crops and animal feed, and consume their own crops and meat products over their entire lifetimes. EPA's analysis shows that even for this theoretical population, only 0.003 new cases of cancer could be expected each year or only 0.22 new cases of cancer over a span of 70 years.

The risk to people in the general population of new cancer cases resulting from sewage sludge containing dioxin is even smaller due to lower exposures to dioxin in land-applied sewage sludge than the highly exposed farm family that EPA modeled.

EPA's 2001 Dioxins Update to the National Sewage Sludge Survey indicates that dioxins levels in treated sewage sludge have declined since the last EPA survey in 1988. This downward trend is expected to continue as regulatory controls are placed on additional sources of dioxins in the environment, particularly on some combustion practices.

EPA Issues Guidelines For Section 319 Grants
EPA has released guidelines for implementation of nonpoint source management programs under Section 319 of the Clean Water Act and for the award of Section 319 grants to states to implement those programs.

These guidelines apply to grants appropriated by Congress in Fiscal Year 2004 and in subsequent years. The guidelines continue EPA's policy of focusing a significant portion of Section 319 funds ($100 million annually) to address watersheds where nonpoint source pollution has resulted in impairment of water quality. The remaining funds are to be used by states to assist in the implementation of their broad array of programs and authorities to address all of the water quality threats and impairments caused by nonpoint source pollution.

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