CSOs Plague Puget Sound; Seattle, King County Get their Orders

The city of Seattle and King County have agreed to increase their efforts to protect Puget Sound from wastewater overflows during severe rainstorms, according to compliance orders issued Aug. 26 by the U.S. Environmental Protection Agency.

EPA issued the orders to address violations of the two governments’ federal Clean Water Act wastewater discharge permits.

“We know that sewer overflows regularly deliver harmful pollution to Puget Sound,” said Michelle Pirzadeh, EPA’s acting regional administrator in Seattle. “What we are requiring of the city and county is clear: They must take steps to reduce the volume and frequency of overflows. We must make sure our treatment plants are doing their best to reduce the amount of untreated wastewater entering Puget Sound waters.”

Seattle and King County have combined sewer systems. Seattle currently manages 92 combined sewer overflow locations and King County manages 38, each of which routinely discharge untreated water during heavy rain into Lake Union, Lake Washington, the Duwamish River and Puget Sound. In 2007 Seattle’s system overflowed approximately 249 times and King County’s system overflowed approximately 87 times.

Both the city and county have already added some water storage capacity to their systems, which has reduced the volume of overflows.

The city’s compliance order addresses wastewater discharge permit violations found during a March 2008 EPA investigation. The order requires Seattle to prepare an overflow emergency response plan, a plan to ensure the collection system is cleaned in a more systematic way, and a plan to create more collection system storage to prevent some CSO overflows from discharging. The order will also require the city to prepare a plan to reduce the number of basement backups and a plan to reduce the number of dry weather overflows. EPA expects the city to be in compliance with the conditions of the compliance order by 2012.

The King County compliance order requires the county to submit a plan to observe and document some of its CSO outfalls after a rainfall event to ensure there is no debris being discharged with the CSOs. The order also requires King County to upgrade their Elliot West CSO Treatment Plant to ensure proper treatment of overflows that may occur there during wet weather events. EPA expects the county to comply with the order by 2010.

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