Policy News - December 11, 2003

Sewage treatment operators get a break

U.S. EPA officials have proposed that during periods of heavy rainfall, sewage treatment plant operators can skip one of the treatment steps required by federal law before the water is released into waterways.

The proposal, which was released in November, is an attempt to address the large volumes of water passing through treatment plants during heavy storms. States and municipalities have for years been unable to fund the expansion of current treatment plants or to build new ones, and as a result, they have been forced to bypass certain parts of the treatment process. The move is also aimed at clarifying the so-called bypass requirements in the Clean Water Act (CWA), which have been interpreted differently by various EPA regional offices and state permitting authorities.

Under normal conditions, sewage coming into a facility undergoes primary treatment, where large solids are removed. This is followed by secondary treatment during which microorganisms biodegrade pollutants. Finally, the effluent is disinfected to kill pathogens before being discharged into waterways.

Because the biological treatment units generally can’t accommodate wide variations in flow volumes and pollutant concentrations, many plants must divert the heavier flows that can occur with wet weather and snowmelt, omitting secondary treatment. As a result, partially treated sewage is blended with fully treated sewage before being discharged. EPA’s proposal would formalize this practice but would still require facilities to comply with all the limits based on secondary treatment standards that are specified in their discharge permits.

Allowing such bypasses prevents the microorganisms that treat the waste from being washed out of the system, says Kevin Weiss in EPA’s Office of Wastewater Management. Additionally, facilities are able to partially treat much higher volumes, “which is a good thing,” he notes, because it reduces the likelihood of plants releasing untreated sewage.

Nancy Stoner, director of the Natural Resources Defense Council’s clean water project, contends, however, that the practice is illegal and contributes to numerous beach closures nationwide every year. EPA officials instead should focus on helping financially strapped municipalities build additional treatment and storage capacity, Stoner says.

But requiring plants to fully treat all incoming flows would be impossible, because it would cost billions of dollars to expand current capacity, and finding the room to build new plants in urban areas is not easy, says Adam Krantz of the Association of Metropolitan Sewerage Agencies.

It is unclear what the risks are of sending blended sewage into waterways, EPA officials admit. Under the proposal, sewage treatment facilities will have to monitor their blended discharges, something that’s not currently required. Additionally, the agency plans to provide Congress with a report on sewer overflows in mid-December. Comments on the proposal are due on January 9. For more information, go to www.epa.gov/npdes/blending. —KRIS CHRISTEN