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WHAT IS A RAIN GARDEN?
Water collects in rain gardens and is filtered through the plants and the soil
Reduces speed of water, lessening erosion damage that usually occurs from fast-moving runoff
Removes pollutants and excess nutrients from the water Recharges groundwater with filtered water Reduces polluted runoff water that enters waterways
FALLS LAKE CLEAN WATER REQUIREMENTEPA requirements for the Falls Lake
Watershed:20% reduction in total nitrogen by 2016 If the lake quality fails to improve by 2016, a $115 million upgrade of Raleigh’s E.M. Johnson Treatment Plant will be needed .
Other improvements may cost an additional $200 million.
OUR GOALOur proposed rain garden will remove ~ 1 lb of nitrogen per year, ~0.1 lb of phosphorous per year, and ~ 60lb of suspended solids per year
Engage local community to construct neighborhood and backyard rain gardens
Assist local homeowners with rain garden construction to expand the impact of the best management practice.
OUR CURRENT LOCATION
Fig. 2 Heavy runoff from parking lot during rain event
Fig.1 Current site: Royall Parking Lot
Impervious Area = 6390 square ft
Pervious Area = 1278 square ft
Total Drainage Area = 7668 square ft
Imperv. Percentage in Watershed(%) = 83
Pervious Percentage in Watershed(%)=17
Rv (runoff coefficient) = 0.67
V(runoff volume) = 42 cubic ft
Partial sun exposure
Appropriate site; not wet/saturated 1.5 days after rainfall
Soil Type: urban soil
Rain Garden Size: 1024 square ft
Peak storm water runoff C (runoff coefficient) = 0.73 I (peak storm water runoff) = 7.2
in/hr Q (peak flow) = 0.092 cubic
ft/second
SITE MEASUREMENTS
TIMELINE + SUBMISSION
Deadline: March 27th, 2013 @ 9:00 AM
If you have any questions, please contact [email protected]