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FORMULAS FOR CALCULATION OF A <br /> STORM DRAIN POND 'S VOLUME <br /> BASIC RUNOFF 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 3. 12 ( 0.26 ' ) <br /> ( a 10- ye-or , 48 - hour storm ) <br /> FORMULAS <br /> POND BASIN = x 1 . 00 x 0.26 <br /> PAVING = -. x 0. 95 x 0.26 = <br /> ROOF = -y x 0. 80 x 0.26 z <br /> COMP. EARTH = 6: coa x 0.75 x 0.26 <br /> LAWN a = i ,'7, 376 x 0.20 x 0.26 <br /> LANDSCAPE <br /> SUBTOTAL <br /> THE NEEDED POND CAPACITY = SUBTOTAL X 2 = <br /> VOLUME DETERMINED WITH NO ALLOWANCE FOR PERCOLATION . ) <br /> y s <br /> CUA 'S `/ycv 4 <br />