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Swale on Yale

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(Seattle, WA w/ZGF) A project to build four swales in Seattle's South Lake Union area within the Cascade neighborhood. A partnership between the private developer Vulcan and Seattle Public Utilities, this project highlights a public/private approach integrating a public drainage system with private property redevelopment. In doing so, the project maximizes construction efficieincies, creates a mechanism for sharing maintenance requirements, and reduces overall project costs. Not only will the swales provide a much needed benefit for the water quality of Lake Union, but it will also enhance the neigborhood with surface water, plants and wildlife.

Text of Swale on Yale

  • I-5

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    CAPITOL HILL

    LAKEUNION

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    PROBLEM

    Stormwater from Capitol Hill flows across streets and sur-faces collecting particles and contamination before the 475 acres (188 million gallons per year) of runoff head to the storm drain pipe that empties into to Lake Union. This process contami-nates the lake with silt, heavy metals, fertilizers, and patho-gens that affect plant and animal habitat as well as human conditions. Typical stormwater treatment plants designed to remove these pollutants are expensive and unattractive interruptions to the urban environment.

    SOLUTION:

    Stormwater will be treated through a vegetated fil-ter called a bioswale, an earth channel planted with erosion resistant and flood tolerant grasses, that re-moves contaminants collected in Capitol Hill while creating a neighborhood amenity in Cascade and improving the water quality conditions of Lake Union. This win-win situation takes advantage of new development to meet rising infrastructure demands of associated hardscape through a less invasive and more cost effective means. Stormwater from be-low ground pipes will be pumped into four street-lev-el bioswales that will naturally treat 188 million gal-lons of stormwater every year.

    SOUTH LAKE UNION

    Republican St

    Harrison St

    Thomas St

    Yale

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    SWA

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    188 million gallons of Capitol Hill runoff willflow through the swales.

    Swales remove 60% of contamination

    The effect of this natural system will have an over-all impact of cleaning the lake by reducing con-taminants by 4%.

    WATER RUNS FROM HIGH POINTS TO LOW

    Runoff from the Capitol Hill drainage basin naturally flows towards the South Lake Union Neighborhood.

    VEGETATION NATURALLY CLEANSES STORMWATER

    Particulates and chemicals in rain water-runoff can be treated without mechanical means through planted channels called bioswales.

    Pike Place market

    CASC

    AD

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    EIG

    HBO

    RHO

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    Denny Way

    Valley St

    convention center

    WHERE IS IT?SEATTLE, SOUTH LAKE UNION AND CASCADE NEIGHBORHOOD

  • Yale

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    188 million gallons a year from Capitol Hill

    72" main

    24" to swales

    Pre-treatment

    Water flows into swales at a maximum 8 cubic foot/second

    Stormwater run-off from Capitol Hill98 Mg/L total suspended solids TSS(low 49 Mg/L high 180 Mg/L)

    Pre-treatment vault removes sediment, floating debris, and free oil

    72" Main

    Swales removeaverage 60% of total suspended solids. (Between 40% to 70%)

    Ponti

    us Av

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    Yale

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    Thomas St.

    Harrison St.

    Republican St.

    Swales have a 1%-2% slope12" pipe

    Stormwater entering South Lake Union 39 Mg/L total suspended solids

    12" pipe

    Low water velocities combined with healthy strands of thin stemmed plants allow particles and pollution to settle out of stormwater. Swales es-sentially act as small constructed wet-lands.

    SWALE REMOVAL RATES

    PRE SWALE

    POST SWALE

    total suspend-ed solids

    38%

    100%

    total phospho-rous

    14%

    37%

    total nitrogen

    14%

    55%

    nitratenitrogen

    13%

    44%

    metals

    9%

    71%

    SWALE BY NUMBERS4 blocks

    2 streets

    8 inches of water at full capacity

    43 Tons of total suspended solids removed annually

    188 million gallons of water treated annu-ally

    $8 million construction costs

    cost of effective water treatment projects

    HOW DOES IT WORK?UNDERSTANDING THE SWALE

    24" Drain pipe to swales

    60'-0" ROW

    the street above ground

    the pipesbelow ground

  • VASTRA HAMNEN HOUSINGMalmo Sweden

    THE MERIWETHERPortland Oregon

    VASTRA HAMNEN HOUSINGMalmo Sweden

    THE MERIWETHERPortland Oregon

    SWALESeattle Washington

    If all the worlds water were fit into a gallon jug, the fresh water available for us to use would equal only about a teaspoon.

    WHERE ELSE HAS IT BEEN DONE?

  • Give nature the space to grow and youll be amazed by the results.

    VEGETATION NATURALLY FILTERS AND SLOWS STORMWATERPlants are natural filters. Particulates and chemicals in rain water runoff can be treated without mechani-cal means through planted channels called bioswales.

    HEALTHY ECOLOGIES LEAD TO HEALTHY PEOPLEBiophilia describes the instinctive at-traction of humans to nature and oth-er living systems, an affiliation that is deeply rooted in our biology. Studies show that people who have regular access to and views of natural sys-tems are happier, healthier, and more productive.

    SWALES ARE SWELL

    Earth channels planted with ero-sion resistant and flood tolerant gas-ses have the capacity to retain pol-lutants, slow water velocity, and disconnect impervious areas from downstream waterways.

    The Alcyon and P-Patch Community Gardens

    Cascade Neighborhood, Seattle's pioneer of Sustainability

    New Development

    Swale

    Yale Street

    The Cairns

    WHAT DOES IT DO?CREATES A HEALTHY URBAN ENVIRONMENT

    looking north on yale street

    view looking east accross yale from new home