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V. Design Calculation Summary <br />See Appendix C for calculations <br />Table — Runoff Rate <br />Rainfall Event <br />(Type II 24 -hr) <br />Existing <br />(cfs) <br />Proposed <br />(cfs) <br />2 -year <br />5.23 <br />4.76 <br />1.0-year <br />9.87 <br />8.75 <br />100 -year <br />16.67 <br />16.13 <br />Table — Filtration Volume <br />BMP <br />Filtration Volume <br />(cf) <br />Central Pond <br />4,360 <br />Parking Lot Islands <br />1,150 <br />Underground <br />Filtration System <br />6,400 <br />Total Provided <br />11,900 <br />Total Required <br />11,808 <br />Table — High Water Levels <br />BMP <br />Bottom <br />Overflow <br />HWL <br />Central Pond <br />929.0 <br />933.1 <br />933.7 <br />Underground <br />Filtration System <br />921.0 <br />923.0 <br />924.1 <br />VI. Construction Discussion <br />Temporary sediment basins will be constructed to treat construction runoff. The basins will be <br />located at the location of the new proposed basin at the center of the site, and the snow melt <br />basin east of the bus turnaround. Final elevation and construction of the sediment basins will <br />be determine after on -site inspection for existing containments are completed and <br />recommendations provided for their design. If unsuitable soils are encountered in identified <br />infiltration areas, they will be replaced with engineered soils. <br />Temporary erosion and sediment control measures are included in the design plans to minimize <br />construction impacts and meet the NPDES Construction Storm Water Permit requirements. <br />Hwy 36 and Rice Street Park and Ride <br />Storm Water Narrative — 50% Review Set <br />7/20/2011 <br />Page 15 <br />