Brightwater Treatment Plant–a clean water treatment facility

The plant

Brightwater treatment plant, April 2011

The Brightwater treatment plant is located along State Route 9, north of Woodinville, in unincorporated Snohomish County. Treatment and support facilities cover approximately 43 acres, with additional area for stormwater treatment, open space, wildlife habitat and wetlands

Treatment plant design 

The plant design integrates landscape, architecture, wildlife habitat, engineering, art, and education. The goal is to enhance the local community and add wastewater treatment capacity for our region.

Treatment plan has the capacity to treat an average of 36 million gallons of wastewater per day (mgd). By 2040, treatment capacity may be expanded to 54 million mgd. These capacities are for average wet-weather flows (AWWF). The plant must also be able to accommodate peak hourly flows of 130 mgd at start-up and 170 mgd by 2040.

Site plan (PDF) of the Brightwater Treatment Plant, December 2005

The treatment plant site includes:

• Wastewater treatment systems
• Biosolids production
• Advanced treatment of nearly all flows to Class A reclaimed water standards
• A state-of-the-art odor control system
• Attractively designed facilities that blend in with the surrounding neighborhood.
• An Environmental Education and Community Center and more than 40 acres of open space, restored habitat and trails for public use at the north end of the site.

Conveyance and outfall

The Brightwater system also includes a conveyance system for bringing untreated wastewater (called influent) to the plant and for bringing treated wastewater (called effluent) from the plant to the marine outfall in Puget Sound. There are also separate pipes within the system to convey reclaimed water.

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 parts of the tunnel contain up to four pipes going to and from the treatment plant while other sections contain only a single pipeline that will carry highly treated effluent to Puget Sound.

Brightwater's mile-long, 600-foot-deep outfall is located a mile off of Point Wells in Puget Sound. The outfall consists of twin, 5-foot-diameter pipes with a diffuser at the end where highly treated wastewater will be discharged into Puget Sound. During the Brightwater siting process, the county worked with the University of Washington to study the marine biology and geology of Puget Sound to evaluate potential locations for the outfall. The study significantly advanced the scientific understanding of Puget Sound, and provided additional insight as to how people use the water and shoreline for sustenance, commerce and recreation.

Brightwater System map (PDF)

Brightwater Environment Education and Community Center and public open space

The Brightwater Environmental Education and Community Center (EECC) was built as mitigation for the Brightwater treatment facility construction. The center includes event space rentals for up to 250 people, with meeting spaces for community groups, conferences, business meetings, weddings and other special events. The center hosts environmental education programs and facilities for school grads 4-12. There is also 70 acres of open space, trails and wildlife habitat open for public use. Here you will find lush forest, meadows, wetlands, creeks and ponds which have been restored to create wildlife habitat areas.