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Basin Information and Lag Time Computation 11 <br />Project Title: Parkdale Granite Quarry <br />Catchment ID: B <br />1. Catchment Hydrologic Data <br />Catchment ID = B <br />Area = 109.50 Acres <br />Area = 0.1711 Square Miles <br />Percent Imperviousness = 5.00 % <br />NRCS Soil Type = D A, B, C, or D <br />II. Analysis of Flow Time (Time of Concentration Tc) for a Catchment <br />Using SCS Lag Equation (1975) <br />Developed for small (<2000 acres) watersheds <br />Equation assumes Tc = 1.67"Basin Lag <br />Tc = 100L0.8[(1000/CN)-9]0'7 / (1900So) <br />Avg. slope for longest watercourse S = 19.6 % <br />SCS Curve No. CN = 84 Land use assumed to be Pasture/Range in FAIR condition <br />Length of Water Course L = 6,128 feet <br />Tc = 27 minutes