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Natural Resources and Parks

King County, Washington
2006 DNRP archived news: this news release may include broken links and outdated information such as programs and contacts that no longer exist.
May 18, 2006

Grease-blocked sewer pipe causes overflow in Bellevue

City of Bellevue crews quickly responded last week to a local sewer overflow that was later found to be caused by a grease blockage in King County's Issaquah Interceptor. The interceptor is a large sewer line that carries wastewater from homes and businesses in the Issaquah and Bellevue areas to the county's regional wastewater plant in Renton for treatment.

Between 5,000 and 15,000 gallons of wastewater overflowed from a manhole near the intersection of S.E. 47th St. and 194th Ave. S.E. into a nearby creek that flows to Lake Sammamish. City of Bellevue staff stopped the leak, cleared the blockage, and began clean-up. To protect public health, they posted a nearby beach as closed, took water samples, and told health and regulatory agencies about the leak.

"City of Bellevue staff deserve recognition for their prompt, professional response," said King County Wastewater Treatment Division Director Don Theiler. "Even though it was later found to be our pipe, their quick action kept the overflow from becoming a much bigger problem."

King County is working with City of Bellevue to understand how so much grease could block such a large pipe so they can prevent it from happening again.

Grease gets into the sewer system from household drains or businesses with poorly maintained grease traps, where it sticks to the insides of pipes. Over time, grease build-up can block an entire pipe and cause sewage overflows.

"One of the best ways people can keep fats and grease out of the sewer is to keep it out of their drains," said Theiler. "Not only does it help prevent sewer system overflows, it can help people avoid their own costly plumbing problems."

People can get more information about how to properly dispose of fats, oils and grease, by visiting or calling the Wastewater Treatment Division at 206-684-1280 or 711 TTY.