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•' <br />CALCULATIONS FOR DIP-CROSSING DIMENSIONS <br />MID-CONTINENT LIMESTONE QUARRI' <br />PERMIT NO. M-82-121 <br />Max. ]0-er 24-hr storm 2.0" <br />Area est. at. 10 acres <br />Precipitation = (10)(2) = 20"-acres/24 hrs <br />Assume no seepage, i.e. 100% runoff. <br />20"-acres/24hrs = 1.667 acre-ft/24 hcs <br />CF/24 hrs = 143,560)(1.667) = 72,615 CF/24 hrs <br />72,615/(24)(60)(60) = 72,615/86,-100 = 0.84 CFS <br />Q = CLHt2/3 (p.21.74, Art. 21.44, for <br />weirs not sharp-crested*) <br />Where Q = CFS <br />C = coefficient of discharge = 2.64 (p. 21.79*) <br />L = effective length of ditch <br />H = total head on crest, including velocity <br />head at approach <br />H3/2 = 0.84/(2.641(10) = 0.84/26.4 = (0.03212/3 <br />H = 0.101 ft <br />Water depth in dip crossing for 10-y~r 24-hr storm will be <br />0.101 ft or 1.21 inches. <br />*Standard Handbook for Ci~~il Engineers, 3rd ed., by <br />Fredrick S. Merrott. <br />