SEATTLE, WA, Aug. 9, 2006 -- Construction will soon begin on six miles of underground tunnels to serve the sewage treatment needs of people in south Snohomish and north King counties in Washington state. The tunnels for the Brightwater treatment system are part of the region's largest clean water project in 40 years.
King County recently awarded a $209.7 million construction contract for the central portion of the Brightwater conveyance tunnel to Vinci/Parsons RCI/Frontier-Kemper, a joint venture based in Montreal.
Construction of the 14-foot-diameter tunnels will begin Aug. 28. Crews will use tunneling equipment that works long distances underground without disrupting surface streets and neighborhoods.
This is the second of three Brightwater construction contracts to build a 13-mile tunnel that will carry wastewater to and from the new Brightwater treatment plant when it comes online in 2010.
The scope of work on the central tunnel contract includes building two tunnels, one from Kenmore to the North Creek Business Park in Bothell and another from Kenmore to Ballinger Way Northeast in Shoreline. The combined length of the tunnels will be about six miles.
Crews will also excavate two deep shafts -- one near the intersection of 80th Avenue Northeast and Northeast 192nd Street in Kenmore, and another along Ballinger Way Northeast in Shoreline -- to launch and remove the tunnel-boring machines.
The contractor will install six pipes in the tunnel ranging from 14 inches to 126 inches in diameter along with two fiber-optic cables to monitor Brightwater facilities.
The North Creek to Kenmore tunnel segment will hold a 72-inch-diameter pipe to carry treated wastewater through the system to an outfall in Puget Sound, a 54-inch pipe to carry untreated wastewater to an influent pump station where it will be pushed to Brightwater for treatment, and a 24-inch pipe for reclaimed water.
The Kenmore-to-Shoreline segment will hold two 14-inch reclaimed water pipes and a 126-inch-diameter pipe to carry treated wastewater to the outfall.
Portions of the tunnel around the pipes will be filled with concrete after those installations. In addition, the contractor will trench a smaller 3,400-foot-long pipeline from the Kenmore portal to connect the new Brightwater pipes to the existing local sewer system using a combination of open-cut and microtunnel construction.
Construction on the central tunnel is scheduled to be completed in 2010.
At $209.7 million, the winning bid is more than $20 million under the county engineers' estimate of $229.9 million. The county and its consultants thoroughly reviewed Vinci/Parsons RCI/Frontier-Kemper's qualifications before awarding the contract.
The county has already selected Jacobs Civil to provide construction management services for the conveyance facilities. MWH/Jacobs Associates is designing the system as a joint venture, and CDM is providing geotechnical work as part of tunnel design.
Brightwater tunnel construction on the east segment of the conveyance system has been under way since March. Kenny/Shea/Traylor was awarded the contract to build the Brightwater tunnel from North Creek to the treatment plant site on State Route 9.
King County is currently seeking bids on the Brightwater west tunnel contract, which closes Sept. 21.
More information about the Brightwater project, including the status of construction-related contracts, is available on the project Web site at http://dnr.metrokc.gov/wtd/brightwater/index.htm.
