complete drainage report rev 9

Docusign Envelope ID: E802A2F1-2485-417E-948D-E0A4008C75BD 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 The small-scale infiltration basin is considered green technology for both groundwater recharge and water quality. Porous Pavement system 8 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 2.92: 1. The system will have soil replacement with a permeability of 4 in/hr with a factor of safety of 2. Contributing areas 61042.8 Roof 11,475 sf Porous Pavement 15,545.0 Lawn and other contributing areas 34022.8 sf Ratio 2.92:1 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. 9