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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