Project has Built in Rain Gardens to Filter Stormwater Pollutants

Located in the heart of downtown Tacoma, the Pacific Avenue Streetscapes project has built in rain gardens to filter stormwater pollutants out before going to Puget Sound.

Why Treat Stormwater?

When it rains, oil and other pollutants are picked up in stormwater and can flow untreated into local waterways and ultimately Puget Sound. These pollutants have negative immediate and long-term impacts on surface water quality and fish habitat. Green stormwater infrastructure projects filter rain and stormwater runoff, benefiting the health of our waterways and the animals that live within them.

​Pacific Avenue

Pacific Avenue was the quintessential main street at the turn of the century. It was where the Transcontinental Railroad met the waterway. The Pacific Avenue Streetscape project builds on the history and geography that makes Tacoma unique. It leads the community into a sustainable future as a thriving downtown which attracts visitors and encourages new business.
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Bioretention - Stormwater Treatment and Amenity

Stormwater within the Pacific Avenue Streetscapes Project is treated through bioretention, a treatment technique which uses special treatment soil to filter out pollutants. Bioretention is an engineered form of the facility often referred to as a rain garden. Stormwater flows into the bioretention facilities from the roadway surface and then filters through the treatment soil media. The treated water is collected and returned to the city stormwater system for discharge into Puget Sound. A combination of bioretention soil mix and filter media is used to ensure proper treatment capacity for the contributing areas. The plants within the facilities help keep the soil from compacting and increase removal of pollutants. Running down Pacific Avenue  from South 7th to South 15th Street, this project includes 14 small scale, distributed bioretention facilities which provide stormwater treatment for 6.3 acres of existing roadways that previously discharged into the Thea Foss Waterway and Puget Sound without treatment.

Project Benefits

The project's stormwater facilities improve the overall water quality of stormwater prior to discharging into the Thea Foss Waterway.

Other project enhancements include new sidewalks, intersection bulbouts, crosswalks, lighting, bike sharrows, wayfinding signage and transit stops. Historic granite curbs that were reclaimed have been added to some of the bioretention facilities as flow spreaders and decorative elements. This project has enhanced accessibility, safety, and the overall pedestrian experience on Pacific Avenue.
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Design

This project illustrates that a stormwater facility can also be an amenity to the surrounding area through innovative design, the inclusion of art, an attractive plant palette and other decorative elements. Partners on the project included Tacoma Environmental Services, Tacoma Public Works, and AHBL Consulting.
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Additional Information

Please see our Pacific Avenue Streetscapes handout for more details.

  
    Merita Trohimovich, P.E.
    Environmental Services Department
    (253) 502-2103
    mtrohimo@cityoftacoma.org

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