Construction - Pt. Wells/Marine Outfall  >>> to construction activities Construction activities - Point Wells/Marine Outfall, and as of Sept 2010 includes two miles of tunneling between Ballinger Way and Lake Forest Park20555 Richmond Beach Dr NW, Shoreline, Wash. In response to growth in our region, King County is building a new wastewater treatment system called Brightwater to serve north King and south Snohomish counties. Brightwater construction activities are centered at five sites: the treatment plant site in Snohomish County near Woodinville; and four conveyance construction sites—called portals—in Bothell, Shoreline, Kenmore, and at Point Wells unincorporated Snohomish County. Underground tunneling is underway between the portals and is not generally visible to the general public. Construction on the entire project started in 2006. Treatment plant start-up and operations will begin in 2011, with the entire system scheduled to be completed in 2012. Two Brightwater Projects at Point Wells Portals, pipelines and tunnelingConstruction at Point Wells started in spring 2007 and will continue until 2012. The West Tunnel project is part of the conveyance system, a network of pipes that brings wastewater to the treatment plant and treated wastewater to Puget Sound. These pipelines are being built in tunnels from access points called portals, reducing impacts to surrounding communities. Workers and equipment enter the tunnel through the Point Wells portal, a rectangular shaft about 35 feet deep, which serves as the access point for this portion of the 13-mile Brightwater tunnel system. In 2008, a tunnel boring machine (TBM) was lowered into the shaft and tunneling began. As the TBM moves forward along the conveyance route soil is mined and removed while a concrete lining is installed inside the tunnel. At this site almost all the excavated material is being hauled away by barge. The tunnel is 10 to 13 feet in diameter; the tunneling from Point Wells to the Ballinger Way portal in Shoreline is now complete. In early 2010 the county made changes to the tunneling contracts so that this TBM will continue for an additional two miles east to Lake Forest Park from the Ballinger Way portal. See right side bar for additional information about this work. The TBM used here is an earth pressure balance machine (EPB), manufactured by Lovat, Inc, of Toronto, Canada. TBMs of this scale can mine on average about 50 feet a day and can operate almost continuously, except for times of maintenance and repair. After the tunneling is complete, a 10-foot diameter liner will be installed in the first half mile of the tunnel, followed by construction of an underground sampling facility at the Point Wells site. The site will then be restored and landscaped. What can you expect during construction?King County is committed to being a good neighbor and is working to minimize impacts to nearby residents and businesses during construction. Tunneling is the primary construction activities for the conveyance pipeline at Point Wells. If you need to contact us about construction activities for this project, our contact information is listed below. Outfall constructionThe outfall consists of twin pipes extending offshore about one mile into Puget Sound. Treated effluent will be discharged through diffuser ports on the last 250 feet of each pipe. The diffusers lie about 600 feet below the surface. Construction of the outfall began in spring 2008 and was completed in December 2008. King County used a design/build contract for the marine outfall, which took advantage of close designer/contractor relationships to facilitate design and construction. The selected contract team was led by Triton Marine Construction Corporation from Bremerton, Wash. and included American Construction, Dayton & Knight LTD and Anchor Environmental. Vanir Construction and King County managed the project. The two outfall pipes were assembled at a staging area in the Snohomish River at the Port of Everett and were towed 17 miles by tug boats to Point Wells in September 2008. Workers then attached the pipes to on-shore connectors and lowered them in a controlled submergence 600 feet to the bottom of the Puget Sound. This was followed by backfilling and sheet pile removal at the near-shore trench. Design and construction methods helped avoid significant impacts to the environment during a very compressed permitting and construction schedule. The project was completed in one season, even though the contract allowed two. The project also came in significantly under budget. The final cost was about $29 million, 23 percent less than the original project estimate of $38 million. See the 'Updates' column to read about how this project was recognized with a number of prestigious industry honors. Outfall construction details- Brightwater's outfall is one of the deepest in the world. It sits at the end of a 13-mile conveyance pipeline that will eventually carry effluent from the treatment plant in Woodinville to Point Wells before discharging it through the outfall.
- Shored open trench construction was used for pipeline installation from the connection on the beach to -30 feet MLLW. The trench was open cut with side slopes from -30 to -80 feet MLLW where the pipelines daylighted.
- From the seismic anchor on, the outfall consists of twin 63-inch-diameter 5,000-foot-long HDPE pipes with concrete ballast anchors. Each pipe terminates in a 250-foot-long diffuser section composed of 30 six-inch-diameter ports. The diffusers are staggered along the alignment to provide a 500-foot-long mixing zone.
Nearshore restorationKing County and its contractors designed and built the outfall with great attention to environmental protection, and took several steps to minimize impacts during construction in sensitive marine environment. A team of county biologists are currently undertaking final habitat restoration efforts that will includes monitoring of eelgrass as well as other plants and animals in the nearshore Contact us if you need more information about BrightwaterFor construction-related questions and urgent issues, contact the construction information line at 206-205-5989 (remember to dial 911 for emergencies) For general questions and information about Brightwater call 206-263-9453, or 711 for TTY access, or email us at: brightwater@kingcounty.gov
King County Brightwater Project
22505 State Route 9
Woodinville, WA 98072
E-mail: Brightwater
Phone: 206-263-9453
TTY Relay: 711
Driving directions to Brightwater project office. >>>Return to construction activites |
