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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- year , 48 - hour storm ) <br /> (/ FORMULAS <br /> Al <br /> 0 <br /> POND BASIN = x 1 . 00 x 0.2E _ <br /> � <br /> p .L WO PAVING = — x 0. 95 x 0.2 6� <br /> K .100') ROOF x 0. 60 x 0.26/ = 12'1 J <br /> - cIX2f v71< r r <br /> -----00MP EARTH = x 0. 75 x 0.26 = a� <br /> LAWN a - ► x 0.20 x 0.2 4 <br /> 1As, LANDSCAPE SUBTOTAL <br /> * THE NEEDED POND CAPACITY = SUBTOTAL X 2 = ZI Iv <br /> VOLUME DETERMINED WITH NO ALLOWANCE FOR PERCOLATION . ) <br />