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Green Infrastructure:Reconnecting Water, Soils and Vegetation in the
Urban Environment
Michele Adams, P.E. LEED AP
Two important observations:
Volume: 96% of the annual rainfall
volume of 36 inches is from
storms 3 inches or less
Frequency: Most of the time, it rains 1 inch
or less
Annual Percentages of Volume from Storms
A New Paradigm for WaterVolume: Capture the Small Frequent Rainfalls
• Pennsylvania – Volume Increase for 2-Year Event (1 ½” -2”)
• City of Philadelphia: 1” from Impervious Surfaces• US Green Building Council (LEED) – 95% of Rainfall Events
EPA: Mimic Natural Hydrology
• Cathedral and Parking on top of hill
• Surrounded by “Olmsted’s Woods”
• Point Discharges eroding hillside, creating ravines
• Lack of Recharge: Diminished Soil Moisture and Dying Trees
• Invasive Vegetation
Restoration:Washington National Cathedral
Once the Volume is reduced• Repair outfalls and ravines
with check dams• Prevent to continued loss of
groundwater• Make the structures look
natural
Infiltration Trenches
First Step:Reduce the problem by reducing the volume of
runoff
• Direct Runoff to Infiltration Trenches in Lawn
Stormwater in Philadelphia
• Capture first 1-inch of rainfall from impervious surfaces for new development (current rule)
• Stormwater fees restructured in 2010 -monthly charges for impervious and total site areas.
• Stormwater measures can reduce monthly fees
• “Green Streets” designs• Planter boxes, tree trenches, rain
gardens, and bioswales • Use vegetation and soils to manage
stormwater
Urban Schools:Sadie Alexander K-8 School
• Constructed in 2000• Philadelphia Water
Department• Reducing Volume to
Combined Sewers• Urban Green Space:
• Porous Playground• Playfield with
Stormwater Bed Below
• Rain Gardens• Education
Stormwater Infiltration Below Playfield
Sadie Alexander School, Philadelphia
• Roof Leaders from Building to Bed
• Old Urban Fill• Infiltration to Reduce Volume• Urban Green Space
• Education• Access• Infiltration• Urban Green Space
Rain Gardens
Porous Pavement Playground (no puddles!)
Swale to bioretention area
Independence Charter School
Before
Porous Asphalt, Stormwater Cobble Swale to Rain Garden
Clark Park
• Constructed in 2007• Philadelphia Water
Department & PA Horticultural Society
• Infiltration Bed under Asphalt Basketball Court
Street inlet designed with water quality insert and sump to prevent debris and sediment from clogging infiltration bed.
• City and Delaware Horticultural partnership
• Urban Heat Island Cooling
• Capture 1” from Street and Store
Commercial and Parking Lot:Urban Grocery Store in Wilmington
At the Residential Level: Downspout Disconnection
Disconnect downspout from combined sanitary sewer system
•Portland, OR•Chicago, IL•Boston, MA•Minneapolis, MN•Bremerton, WA•Lynchburg, VA•Pittsburgh Nine Mile Run!•Pittsburgh: Nine Mile Run!
Portland, Oregon
• Elimination of 94% of overflows to Willamette River by 2011
• > 44,000 disconnected downspouts (>1 BGY stormwater)
• Residents can do work themselves and earn $53 per downspout
• Community groups earn $13 per downspout
Where Does The Water Go?• Lawns• Other pervious
surfaces • Vegetative swales• Rain gardens• Infiltration trenches• Rain barrels
Boston Disconnect Program
New Residential: Village at Springbrook• High Density Residential• 59 acres• 269 homes:• 146 Townhouses• 96 Quads• 17 Singles• Sinkholes and limestone
Can Water be Managed within the landscape?127 small measures, no detention basins.
The Plan
Existing
Proposed
Vegetable GardenMeadow
Compost
Lawn
Gathering Garden
Patio
Compost
Bird Feeders
Table & chairs
Rain GardenStreet TreesN
N
From Lawn to MeadowNATURAL AREAMeadow Development in Progress
Roxborough Habitat Restoration Project
Beautiful Meadow Coming to your Neighborhood!
Before Before
After After
Brown Thrasher
After
The Rain Garden
Existing
Proposed
Infiltration area under bluestone
Planted swale
Lawn
Patio
Compost
Final treatment
Rain Chains, Spash blocks