LAKE UNION The effect of this natural system will have an overall impact of cleaning the lake by reducing contaminants by 4%.
Fairview Ave
WATER RUNS FROM HIGH POINTS TO LOW Runoff from the Capitol Hill drainage basin naturally flows towards the South Lake Union Neighborhood.
Republican St SWALE
SOUTH LAKE UNION
CASCADE NEIGHBORHOOD
North Dexter
Valley St
Yale Ave East Lake Ave
I-5
Harrison St Thomas St
CAPITOL HILL
Swales remove 60% of contamination
Denny Way Pontius Ave
VEGETATION NATURALLY CLEANSES STORMWATER Particulates and chemicals in rain waterrunoff can be treated without mechanical means through planted channels called bioswales.
188 million gallons of Capitol Hill runoff will flow through the swales. convention center
et ark em lac eP Pik
I-5
WHERE IS IT?
SEATTLE, SOUTH LAKE UNION AND CASCADE NEIGHBORHOOD PROBLEM
SOLUTION:
Stormwater from Capitol Hill flows across streets and surfaces 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 contaminates the lake with silt, heavy metals, fertilizers, and pathogens 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.
Stormwater will be treated through a vegetated filter called a bioswale, an earth channel planted with erosion resistant and flood tolerant grasses, that removes 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 below ground pipes will be pumped into four street-level bioswales that will naturally treat 188 million gallons of stormwater every year.
Re
ta
il E dg
e
Ya le Av e
t n e m p o l e v e Ne w D Pre-treatment
24" to swales
72" main 188 million gallons a year from Capitol Hill
60'-0" ROW
HOW DOES IT WORK?
the street above ground
UNDERSTANDING THE SWALE SWALE BY NUMBERS
SWALE REMOVAL RATES Low water velocities combined with healthy strands of thin stemmed plants allow particles and pollution to settle out of stormwater. Swales essentially act as small constructed wetlands.
4 blocks 2 streets
PRE SWALE
8 inches of water at full capacity 43 Tons of total suspended solids removed annually 188 million gallons of water treated annually
POST SWALE
$8 million construction costs ½ cost of effective water treatment projects
total suspended solids
total phosphorous
total nitrogen
nitrate nitrogen
metals
38%
14%
14%
13%
9%
100%
37%
55%
44%
71%
the pipes
Republ
Stormwater entering South Lake Union 39 Mg/L total suspended solids
ican St.
below ground
. e v A s
Harri
son S t.
Yal e
Swales remove average 60% of total suspended solids. (Between 40% to 70%)
Ave .
iu t n o P
Swales have a 1%-2% slope
12" pipe
Tho m 24" Drain pipe to swales
Water flows into swales at a maximum 8 cubic foot/second
as S t. 12" pipe
Pre-treatment vault removes sediment, floating debris, and free oil 72" Main
Stormwater run-off from Capitol Hill 98 Mg/L total suspended solids TSS (low 49 Mg/L high 180 Mg/L)
VASTRA HAMNEN HOUSING Malmo Sweden
“
THE MERIWETHER Portland Oregon
VASTRA HAMNEN HOUSING Malmo Sweden
“If all the world’s 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?
’ THE MERIWETHER Portland Oregon
SWALE Seattle Washington
Cascade Neighborhood, Seattle's pioneer of Sustainability
Give nature the space to grow and you’ll be amazed by the results.
WHAT DOES IT DO? CREATES A HEALTHY URBAN ENVIRONMENT
New Development
The Cairns
Yale Street
Swale looking north on yale street
VEGETATION NATURALLY FILTERS AND SLOWS STORMWATER
HEALTHY ECOLOGIES LEAD TO HEALTHY PEOPLE
SWALES ARE SWELL
Plants are natural filters. Particulates and chemicals in rain water runoff can be treated without mechanical means through planted channels called bioswales.
Biophilia describes the instinctive attraction of humans to nature and other living systems, an affiliation that is deeply rooted in our biology. Studies show that people who have regular access to and views of natural systems are happier, healthier, and more productive.
Earth channels planted with erosion resistant and flood tolerant gasses have the capacity to retain pollutants, slow water velocity, and disconnect impervious areas from downstream waterways.
The Alcyon and P-Patch Community Gardens
view looking east accross yale from new home