RAIN GARDEN DESIGN

CONTEST 2013

M A R C H 11T H –

27T H

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

WHY DO WE NEED A RAIN GARDEN?

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

MAP OF WATER FLOW

PHOTOS OF WATER FLOW

PHOTO OF WATER FLOW

PHOTO OF WATER FLOW

Impervious Area = 6390 square ftPervious Area = 1278 square ftTotal Drainage Area = 7668 square ft

Imperv. Percentage in Watershed(%) = 83Pervious Percentage in Watershed(%)=17

Rv (runoff coefficient) = 0.67V(runoff volume) = 42 cubic ft

Partial sun exposureAppropriate 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 + SUBMISSIONDeadline: March 27th, 2013 @ 9:00 AM

If you have any questions, please contact agc.ncssm@gmail.com