King County Wastewater Treatment Division (WTD) is hosting a virtual Informational Open House for interested firms to learn about upcoming projects and events. To encourage early teaming arrangements, we hope interested firms attend. For additional event details, visit WTD’s Upcoming Contract Opportunities page.

Event Date/Time

June 24, 2025, at 1 p.m. (PST) 

Duration: Approximately one hour

MS Teams Meeting Link (Registration is required): Register HERE

Link: https://tinyurl.com/WTDOpenHouse-06242025

Once registered, you will receive an email confirmation that will include the meeting link with the option to save a meeting reminder on your calendar.

WTD will provide schedule updates on some of our collaborative delivery projects as well as a number of upcoming construction, consulting and work order contracts and highlight upcoming projects. A brief description of projects presenting at this Open House are below:

Mouth of Duwamish Combined Sewer Overflow (MDCSO) Program: King County Wastewater Treatment Division has initiated the Mouth of Duwamish Combined Sewer Overflow (MDCSO) Program to implement an integrative solution to control the discharge of five Combined Sewer Overflows (CSO) outfalls that occur during wet weather events in Seattle, flowing to the mouth of the Duwamish River. The project area is in the SODO neighborhood and includes sections of the Elliott Bay shoreline within Seattle and the east and west waterways of the Duwamish River on either side of Harbor Island. The five outfalls (Chelan, Hanford #2, Lander, Kingdome, and King Street) are all located in the Duwamish Waterway. The program will build infrastructure to convey, store and treat combined sewer flow during storm events to control CSOs per regulations.

Sammamish Plateau Diversion (GC/CM): This project will address regional conveyance system capacity needs by diverting flows out of the South Lake Sammamish Planning Area north. Diverting flows northward will alleviate capacity needs at several King County conveyance facilities. 

South Treatment Plant (STP) Dissolved Air Flotation Tanks (DAFT) Rehabilitation (ITB): The County’s Wastewater Treatment Division (WTD) will replace DAFTs 1 through 6 process equipment and covers at the STP. The DAFTs co-thicken primary sludge and waste activated sludge. Work includes performing demolition and replacement of the DAFT metal equipment components with new 316 Stainless Steel equipment, conversion of rail track system to cantilever system, new flat aluminum covers, ventilation system upgrades, access improvements, and pilot testing a sludge blanket level monitoring device. The equipment vendor package will include bridge beams, center column with internal motor, two rake arms, eight skimmer arms, two float boxes, and effluent Launder pipe.