complete drainage report rev 9

Docusign Envelope ID: E802A2F1-2485-417E-948D-E0A4008C75BD Porous Pavement system 11 System 11 collects stormwater from Road D, half of the Building D roof and adjacent grass areas The ratio of contributing areas to the Porous pavement area is 2.78 : 1 The system will have soil replacement with a permeability rate of 10 inches per hour with a factor of safety of 2. Contributing areas 84102.7 Roof 32,202.6 sf Porous Pavement 22269.7 sf Lawn and other contributing areas 29630.4 sf Ratio 2.78:1 The proposed Tc for the area flowing to PP11 uses the following input Sheet flow 83 lf @ 4% over grass 8.9 minutes Shallow Concentrated Flow 150 lf @ 3.3% over grass 9 minutes Total Tc = 9.8 minutes The porous pavement system is considered green technology for both groundwater recharge and water quality. PA-2 Discharge Summary STORM WQ 2 10 100 EX PER 17.53 38.43 83.14 8.77 26.90 66.51 2 0 .19 .93 5.38 3 0 0 0 1.15 4 0 0 .10 .81 7 0 .53 1.73 3.65 11 8 0 0 0 .68 9 0 0 0 .16 10 0 0 .93 5.31 11 0 .1 2.25 7.54 UD 3.61 7.21 13.00 24.70 T 3.61 7.24 15.29 38.99