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<br />• <br />i <br />~I <br />i <br />design includes an emergency spillway but does not anticipate the need for a <br />principal spillway. It is planned to pump out water to leave significant <br />storage to accommodate run-off from a ten year, 24 }four storm event. This <br />emergency spillway provides a non-clogging conduit avenue to remoie water <br />storage resulting from inflow. This conduit will be located on the West end of <br />the sediment pond and will be located at a higher level than the maximum sedi- <br />ment storage level. As recommended by PETER O'CONNOR, a staff guage will be <br />installed to determine the 60~ sediment cleanout level. <br />SEDIMENT POND SIZE <br />The pond is 50 feet wide, 50 feet long, and has a normal iepth of <br />about 4 feet. See attached letter from ANNE BALDRIGE. <br />CALCULATION OF SURFACE RUN-OFF <br />PEAK WATER RUN-OFF AND SEDIMENT POND AIZE: <br />By regulation, the ponds must handle precipitation from an expected 10 <br />year, 29 hour storm event. II <br />Referencing: Natural Oceanic and Atmospheric Precipitation Frequency <br />Atlas and Soil Conservation Service's Technical Release Peak Flows in Colorado. <br />Precipitation data is listed. 2.5 inches is the predicted precipitation. <br />Converting inches to acre feet: i <br />2.25 inches water = 0.79 acre ft, water <br />i <br /> <br />Disturbed acreage <br />0.]9 x 8.36 <br />= 3.0 acres excluding road <br />surfaces not in disturbed <br />area <br />.57 acre ft. water <br />to be contained in <br />sediment pond. <br />