The Gravel Detention Expansion project will expand the City of Tacoma’s regional stormwater detention capacity in the Flett Creek Watershed. This proactive watershed approach to managing stormwater will provide additional flow control thereby protecting downstream creeks from erosion and high storm flows. This project will also assist with stormwater flow control requirements for existing development, new development, and redevelopment projects within the Flett Creek Watershed.
A public trail along the eastern perimeter of the property and sidewalk improvements along South 80th Street will also be constructed as part of the project. This will open up this 25-acre green space for the neighborhood to enjoy and the trail will improve the walkability of this area.
Facility Elements
Stormwater Detention
The detention facility will hold about 300,000 acre feet of stormwater after an additional 56 acres of storage is added through this project.
Public Trail
About a half-mile of gravel trail will be added along the eastern edge of the lake-like detention facility. This trail will be 5 feet wide, with a gentle maximum slope of 5 percent (ADA accessible). The trail will have a 4-foot tall chain-link fence on the downhill side.
80th Street Sidewalk Improvements
Over 1,000 feet of sidewalk with street trees will be added along 80th Street.
Landscape Improvements
Drought tolerant, low-maintenance landscaping at the entrances will welcome pedestrians into the facility. A mixture of ornamental and native grasses and trees will provide open views into the site, while accommodating for shade and shelter during the summer heat.
Existing native trees adjacent to the detention facility will be preserved and new wildflower prairie meadows will be seeded along the trail.
Project Cost and Funding Sources
A $3 million grant from the state Department of Ecology is helping pay for the facility, along with funding from the City of Tacoma Surface Water Management utility.
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City of Tacoma Surface Water Fund
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$600,000
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WA State Department of Ecology Grant
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$3,000,000
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Total
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$3,600,000
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Project Timeline
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Task
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Estimated Completion Date
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Concept & Permitting Phase
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January 2014-September 2015
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Design
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Preliminary: October 2015-February 2016
Final: March-April 2016
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Contracting Process
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May-June 2016
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Construction
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July-October 2016
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Community Involvement and Education
A public meeting was held on April 19, 2016, at the Tacoma Central Presbyterian Church, 8001 S. Pine Street.