King County, Wash., wastewater plant meets regional needs

Brightwater, the third regional wastewater treatment facility in King County, Wash., opened in August after nearly 10 years of development. The 39-million-gallon-per-day membrane bioreactor (MBR) facility is designed to treat wastewater for up to 510,000 users and help the county reach its goals of reclaimed water production.

King County identified the need for the regional wastewater treatment facility in the late 1990s. The county contracted with Denver-based CH2M HILL as the prime consultant in partnership with Walnut Creek, Calif.-based Brown and Caldwell for 10 years, and the two firms led a team of 17 consulting firms to deliver the treatment plant. Work on the treatment plant siting evaluation and permitting began in 2001.

The plant’s MBR is the largest in North America. The liquid process uses an innovative split flow treatment design, in which peak wet weather flows exceeding the MBR capacity undergo advanced primary treatment and blend with the MBR effluent before discharge, satisfying all permit requirements. Complete automation of systems across the plant reduces operational costs and allows for unstaffed remote operation when necessary.

The facility design also incorporates features that reduce lifecycle costs. Reclaimed water is used on site for landscape irrigation, toilet and urinal flushing, and a water feature; as well as off site for irrigation and cooling uses. Large windows and skylights provide natural light for working spaces while helping reduce energy consumption.

The treatment plant site also features the Brightwater Center, a LEED Platinum-designed environmental education and community center with a public meeting space, areas for interpretive displays, and teaching and laboratory facilities.