Rain Garden Design Contest 2013

1. Rain Garden Design Contest 2013 March 11th – 27th

2. 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

3. Why Do we need a rain garden?

4. Falls Lake Clean Water requirement • EPA 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.

5. Our goal • Our 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.

6. Our Current Location Fig.1 Current site: Royall Parking Lot Fig. 2 Heavy runoff from parking lot during rain event

7. Map of Water Flow

8. Photos of Water Flow

9. Photo of Water Flow

10. Photo of Water Flow

11. Site Measurements • 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 • 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

12. Timeline + Submission • Deadline: March 27th, 2013 @ 9:00 AM • If you have any questions, please contact agc.ncssm@gmail.com