Revised Stormwater Management Report

DocuSign Envelope ID: DB0533B0-B14B-449D-A0A8-3B9C3C0DF5D9 Small Scale Infiltration Basin 7 This stormwater system collects water from the parking lot and grass areas behind the clubhouse as well as Warner Road. The total contributory area is 2.45 acres. The system will have soil replacement with a permeability of 4 in/hr with a factor of safety of 2. The proposed Tc for the area flowing to Basin 7 uses the following input Sheet flow 83 lf @4% over grass Tc= 8.9 min Shallow concentrated flow 277 lf over grass @ 6 % Tc = 1.1 minutes Shallow concentrated flow 40 lf over pavement @ 6.7 % Tc =.1 minutes Pipe Flow 365 lf @ 2.5 fps 2.4 minutes Total Tc = 12.5 minutes Basin 7 is designed as a small scale basin with exfiltration at the rate of the replacement soil with a factor of safety of 2 as an outlet. Pre-treatment is achieved with MTD that is approved for 50% removal prior to discharge to the basin. Porous Pavement system 8 Tc Computations System 8 collects water from part of the clubhouse roof, and portions of Kusik Drive and Warner Road The ratio of non- roof contributing areas to the Porous pavement area is 2.25: 1 The system will have soil replacement with a permeability of 4 in/hr with a factor of safety of 2. The proposed Tc for the area flowing to PP8 uses the following input Sheet flow 100 lf @ 7% over grass 8.3 minutes Shallow Concentrated Flow 65 lf @ 6% over grass .3 minutes Total Tc = 8.6 minutes The porous pavement system is considered green technology for both groundwater recharge and water quality. 8