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Project update

June 8, 2021

Work will begin in June and continue into July and possibly longer, if weather causes delays.

Project description

Every 10 years, King County’s Wastewater Treatment Division (WTD) inspects sewer pipes that lie on the bottom of the lake around Lake Washington and Lake Sammamish. This summer, a contractor and WTD crews will carry out this important condition assessment.

Condition assessments help WTD monitor pipe conditions, maximize usage, and allow us to replace pipes to provide safe, reliable service.

Crews will inspect the Issaquah Interceptor, Kenmore Interceptor, and Holmes Point Trunk lines. Constructed in the 1960-1970s, the lines are made up of more than 50,000 feet of pipe. 

See the full map and flyer.


June and July, 2021, weather dependent.


What to Expect:

  • The lines are underwater so inspection requires special equipment and divers. If you are on or near the water, you may see a barge and boat at locations of underwater maintenance holes.
  • We expect the work at each location noted on the map to take no more than a day. If work extends longer, a structure that provides access to the maintenance hole may be left in place. The location will be marked with buoys and signal lights.
  • We expect this work to happen in June and July but depending on weather conditions, the schedule may change.

For your safety and the safety of our crews, please avoid this operation. If you are out on the water, please pass by at a good distance from the barge and boat.

Contact us

If you have questions about this work, please contact:

Caryn Sengupta: