Brightwater Conveyance System

Conveyance refers to the tunnels, pipes, and other facilities that carry wastewater to and from the treatment plant. The Brightwater conveyance system includes 13 miles of pipeline built in underground tunnels 40 to 440 feet below the surface, shallower connector pipes, and an influent pump station to send wastewater to the plant. Some portions of the tunnel will contain up to four pipes going to and from the treatment plant while other tunnel sections will contain only a single pipeline that will carry highly treated effluent to Puget Sound.

A more detailed map of the system can be found in the Project Library.

Conveyance System Construction

Tunnel boring machine "Luminita" emerged on the Brightwater treatment plant site north of Woodinville in November 2008, completing its 14-month underground journey from Bothell that began in September 2007. View November 18, 2008 news release.

Almost the entire Brightwater conveyance system is being built using tunnel boring machines (TBMs). There are four construction staging areas, called portals, along the conveyance route where the TBMs have been lowered into the ground, excavated material is being removed, and personal, materials and equipment enter and leave the tunnel.

This method of construction limits surface impacts along the conveyance route, with most of the construction activity centered at the portals and the treatment plant site. Approximately one mile of the system (at the North Creek and North Kenmore portals) was built using microtunnel and surface cut and cover methods.

Construction of the conveyance system is divided into different construction 'packages,' each with its own construction schedule. Conveyance construction began in 2006 and is scheduled to be completed in 2012. The county is continuing to work with neighbors and local communities to keep them informed about construction activities.

Conveyance Facilities

In addition to the tunnels and pipes, other facilities are needed for the system, including pumps, flow and odor control facilities, and electrical and monitoring equipment. These will be located at one of the four portals and will become permanent facilities after construction is complete. There will be a large pump station at the North Creek portal site in Bothell and smaller above-ground structures at the Ballinger and North Creek portals. There will also be a small belowground sampling facility at Point Wells. All of these facilities will attractively designed and landscaped.