King County’s Wastewater Treatment Division (WTD) is building a new wet weather treatment station in Georgetown at the corner of Fourth Avenue South and South Michigan Street. As part of the Wet Weather Treatment Station project, WTD is also building a new outfall structure under the First Avenue South Bridge and connecting pipes from the station to the outfall. Read below for updates on all three project areas, highlights from the past month, and upcoming work.
Conveyance Pipes
You may have noticed that our conveyance project area has jumped to the top of the update this month. That’s because we have some big news to share – crews are preparing for roadway work starting as early as March. We are working closely with the Seattle Department of Transportation and King County Metro to minimize pedestrian, driver, and bus rider impacts, and keep folks moving safely through our work area.
Beginning in early March, South River Street underneath the First Avenue South Bridge will be closed for approximately three months. Crews will complete necessary conveyance work, including surveying in the roadway, trenching, placing pipe, and backfilling. A detour route for trucks and commuters is shown in blue on the map below. The detour uses Occidental Avenue South and South Michigan Street.
 During future roadway construction, we expect the following impacts:
. Limited turns to and from driveways: We will work with residents and businesses in advance of driveway impacts.
. Traffic detours and lane shifts: Crews will establish traffic control as approved by the City to safely install pipes under roadways. Uniformed police officers and flaggers will be used as needed.
. Pedestrian detours: People travelling near active work areas will be rerouted for safety.
Near neighbors and the community will be notified as more schedule and construction work details are available.
Treatment Station
Work keeps progressing on the station. At the site, crews are continuing to form structures, install electrical wiring, build the Influent Pump Station, and laying down supporting pipes. This work is expected to continue for the next several months.
Outfall Pipe
Earlier this month, crews working on the outfall pipe wrapped up this phase of in-water work by installing part of the 54-inch outfall pipe that will carry the effluent (treated water) into the Duwamish River. Work to complete the outfall will resume in fall 2019.
Project Highlight: Pipe Float and Sink
Earlier this month, crews successfully installed the first portion of a 54-inch outfall pipe in the Duwamish River. The pipe was installed on the evening of February 4 by crews using two small flat boats to tow segments along the Duwamish River. Once the pipe was in place, a crane and excavator were used to sink the pipe into the Duwamish River. Then, divers helped connect the new pipe to the pipe that had been installed previously.
 The pipe was floated into position before the sun set and then sunk at night to take advantage of the tide.
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