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`t <br /> FORMULAS FOR CALCULATION OF A <br /> STORM DRAIN PONDS VOLUME <br /> BASIC RUN-OFF COEFFICIENTS <br /> SURFACE COEFFICIENT <br /> POND or BASIN 1. 00 <br /> PAVING (concrete , asphalt, oiled surface ) 0.95 <br /> BUILDING or ROOF , , , , , , , , , , , , , , , 0.80 <br /> COMPACTED EARTH ( gravel ) . . . . . . . . . . 0.75 <br /> LAWN or LANDSCAPING 0.20 <br /> RUNOFF CALCULATED AT 5.12" ( 0.26 ) <br /> ( a 10-year , 48 - hour storm ) <br /> FORMULAS <br /> 10 001, <br /> POND BASIN ■Z6o x I G x 1 . 00 x 0.26 • <br /> PAVING 19 2- Brio x 0. 95 x 0.26 a X12- 1 <br /> ROOF . x 0. 80 x 0.26 • <br /> COMP. EARTH■ x 0.75 x 0.26 a <br /> LAWN A x 0.20 x 0.26 <br /> LANDSCAPE <br /> SUBTOTAL <br /> * THE NEEDED POND CAPACITY ■ SU6TOTAL X 2 ■ 7j 4 ¢ 7 6 <br /> VOLUME DETERMINCD WITH NO /ALLLOWA/NCE FOR PERCOLATION . ) <br />