April 28, 2016

Sustainable merit

Photo courtesy of WACA

Tacoma’s new stormwater treatment facility consists of a series of precast concrete pools, troughs and weirs.

Point Defiance Regional Stormwater Treatment Facility

Location: Tacoma

The Point Defiance Regional Stormwater Treatment Facility is designed to improve the quality of stormwater flowing into Commencement Bay.

The city of Tacoma worked with Metro Parks Tacoma to provide treatment for a large section of the North Tacoma watershed that was discharging untreated into Puget Sound.

Metro Parks Tacoma is redeveloping this area of Point Defiance using green infrastructure and integrating stormwater management as an amenity and educational demonstration. This is part of Metro Parks’ Waterfront Phase 1 improvement plan for the park.

The $4.64 million stormwater treatment project is a 5,500-square-foot bioretention facility designed to capture the worst pollutants before they wash into Puget Sound. It is the largest facility of this kind in the area and incorporates numerous innovative approaches.

The treatment facility consists of a series of cascading precast concrete pools, distribution channels (troughs), and weirs designed to evenly distribute the water into the treatment cells with treatment media and an underdrain system that discharge into a swale and, ultimately, Puget Sound.

This project will treat up to 6 million gallons of dirty water every day. This treatment will reduce the load of fine particulate matter that is discharged into Commencement Bay.

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