King County seeking bids for first major Brightwater construction contract

2005 Archived News

King County will take the next major step this week toward building the Brightwater wastewater system when it requests bids for digging one section of a 13-mile tunnel from the future plant to Puget Sound.

The contract will include building a 14,000-foot-long tunnel from the North Creek Business Park in Bothell to the plant site north of Woodinville next to State Route 9. The selected contractor will dig the 18-foot-diameter tunnel using a large machine that can work long distances underground without disrupting the surface.

The contractor will also excavate two deep shafts for launching and removing the tunnel-boring machine, install four pipes in the tunnel ranging from 27 inches to 84 inches in diameter, and install three fiber-optic cables to monitor Brightwater facilities. The tunnel will be filled with concrete after those installations. In addition, the contractor will dig a smaller 2,400-foot-long tunnel from the North Creek tunnel portal to the existing North Creek Pump Station and excavate a smaller shaft for a new Brightwater pump station.

The future Brightwater plant will provide wastewater treatment capacity to serve the growing number of people in south Snohomish County and north King County. Population projections show the new capacity is needed by 2010 to protect public health, the economy and the environment.

See related article: "Route 9 location reaffirmed as 'optimal site' for Brightwater wastewater treatment plant."

The first tunneling project, scheduled to begin in early 2006, has an estimated cost of $170 million. After tunneling is completed, another contractor will build a pump station for sending wastewater to the Brightwater plant.

King County will advertise two more tunneling contracts in 2006.Total construction cost for the wastewater conveyance system is an estimated $705 million.

The county has already selected Jacobs Civil to provide construction management services for the conveyance facilities. CDM did geotechnical exploration for the conveyance system, and MWH/ Jacobs Associates is designing the system as a joint venture.

Formerly known as Metro, the wastewater-treatment utility now operated by King County has been preventing water pollution for 40 years. The regional clean-water agency serves 17 cities, 17 local sewer utilities and more than 1.4 million residents in King, Snohomish and Pierce counties.