complete drainage report rev 9

Docusign Envelope ID: E802A2F1-2485-417E-948D-E0A4008C75BD Porous Pavement system #5 Porous pavement #5 collects stormwater from the Building B parking lot, Building B roof and grass areas around the building. The total drainage area is 1.07 acres with the majority of that area the building roof or the porous pavement surface. The ratio of other contributing areas to the Porous pavement area is 4:1 The areas contributing to the Porous pavement system are 46,607.8sf Roof 26,232 sf connected directly Porous pavement 14,590.0 sf Overland flow area 5785.8 sf Ratio 2.19:1 The system will have soil replacement with a permeability of 4 inches per hour with a factor of safety of 2. The proposed Tc for the area flowing to PP5 uses the following input Sheet flow 40 lf @2% over pavement Tc= .6 minutes Pipe flow 182 lf pipe , 2.5 fps Tc = 1.2 minutes Total Tc = 1.8 minutes The porous pavement system is considered green technology for both groundwater recharge and water quality. The roof area will connect directly with the underground system with pre-treatment before. Porous Pavement system #6 Porous pavement #6 collects stormwater from the parking lot between Buildings B and C, and grass areas around the building. The ratio of total areas to the porous pavement area is 1.9:1 The system will have soil replacement with a permeability of 4 inches per hour with a factor of safety of 2. The areas contributing are 108077.0 sf Porous pavement 37197.0 sf Lawn and other contributing areas 70,879.7 sf Ratio 1.91:1 The proposed Tc for the area flowing to PP6 uses the following input Sheet flow 40 lf @2% over pavement Tc= .6 minutes Pipe flow 450 lf pipe , 2.5 fps Tc = 3 minutes Total Tc = 3.6 minutes The porous pavement system is considered green technology for both groundwater recharge and water quality. 6