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Proposed Wet Weather Policy to Improve Wastewater Treatment

Release Date: 12/19/2005
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Contact: Eryn Witcher, 202-564-4355 /

(Washington, D.C.-Dec. 19, 2005) EPA today proposed a new policy for addressing peak wet weather discharges at wastewater treatment plants. Across the country, many municipal wastewater treatment systems experience problems during heavy rain downpours (peak wet weather), when flows to the wastewater treatment plants exceed the plant's biological treatment capacity. During peak wet weather, limited diversions around biological treatment units can help prevent raw sewage from being discharged into our nation's waters, backing up into homes and other buildings, or damaging biological treatment units.

EPA's goal in proposing this new policy is to ensure that all feasible solutions are used by local governments when addressing problems related to peak wet weather and to improve treatment of wastewater to protect human health and the environment.

"Our peak flow policy puts a premium on stopping leaks and spills, improving treatment, and increasing public oversight," said Benjamin Grumbles, EPA's assistant administrator for the Office of Water. "I commend environmentalists and utilities for working to find common ground on a clean water solution that doesn't rely on dilution."

The policy reflects the joint recommendations of the Natural Resources Defense Council (NRDC) and the National Association of Clean Water Agencies (NACWA). The policy encourages public participation via the National Pollutant Discharge Elimination System (NPDES) permit process, and provides for public notification in the event that a diversion does take place.

The policy states that in limited situations, a NPDES permit can approve anticipated diversions around biological treatment units, provided the facility demonstrates that there are no feasible alternatives and that diverted flows receive a minimum of primary treatment. The policy also confirms that end-of-pipe discharges must comply with Clean Water Act permits, including effluent limitations based on secondary treatment and any more stringent limitations for receiving waters.

With today's proposal EPA anticipates that over time the need for wet weather flow diversions can be eliminated from most treatment plants serving sanitary sewer collection systems. That can happen through various approaches such as enhancing storage and treatment capacity and reducing sources of peak wet weather flow volume.

EPA will accept written comment for 30 days after the policy is published in the Federal Register. To learn more, visit: