King County staff respond to wastewater spill

King County Wastewater staff quickly responded to an equipment malfunction today in a wastewater pipeline in the Sammamish Valley.

King County crews were on site within the hour of the first report of the spill and began collecting wastewater and transporting it to the South Treatment Plant for proper disposal. King County staff were able to quickly divert wastewater from the pipeline, which runs to the South Treatment Plant in Renton, to the West Point Treatment Plant in Seattle.

The leak occurred near in an underground vault with two air pressure relief valves that connect to two force main sewage transmission pipelines. Before the flow in the pipeline could be diverted, wastewater ran out of the underground vault and down a hill, crossing Willows Road and emptying onto agricultural land in the Sammamish Valley. Willows Road was closed for a brief period while wastewater was collected and cleaned from the road surface.

“Our first priority is to clean up the wastewater so that it does not pose a threat to people or the environment, and we are well on our way toward accomplishing this,” said Don Theiler, Director of the King County Wastewater Treatment Division. “Once we have completed the clean-up, we’ll focus our attention on determining the cause of the wastewater discharge and make the necessary repairs.”

The amount of wastewater that spilled from the pipeline is estimated at no more than 150,000 gallons. Theiler said the cleanup is expected to be completed later this evening or early Thursday morning.

King County staff are working with Public Health - Seattle & King County to post signs in the area to warn people of the spill and of possible contaminated areas. Additionally, the Washington State Department of Ecology has been notified of the spill.