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<br />the pond under the 24 hour 100 year, maximum storm event <br />with the primary dewatering device dysfunctional. Please <br />refer to accompanying compilations of applicable statistics, <br />and the reproduction, Flow in trapezoidal channel 4 ft <br />wide", from "Handbook of Drainage and Construction Products" <br />by Armco Drainage and Metal Products, Inc., Middleton, Ohio. <br />Type A riprap, rough (with a "n" rating of 0.04); a grade <br />of 4.7% ,as shown on the accompanying drawing; and a water <br />depth of 0.6 foot produce a flow capacity in excess of 16 <br />cubic feet per second at the velocity rate of 4.5 feet per <br />second. This flow capacity exceeds the anticipated flow of <br />12.7 cubic feet per second resulting from the 24 hour 100 <br />year storm event calculated for the Explosive Storage Area <br />Sedimentation Pond. <br />As shown on the accompanying drawing, the spillway channel <br />is at an angle to the dewatering pipe. This orientation <br />allows the outflow from the spillway to exhaust onto the <br />riprap that functions for the primary dewatering device. <br />With a water depth of 0.6 foot in the spillway channel, a <br />one foot freeboard will exist around the pond. <br />I hope this remedial construction will solve problems at the <br />Explosive Storage Area Sedimentation Pond for several years. <br />Thanks for the opportunity to be of service. <br />Res ctfull,v submitted, <br />.%~ <br />Eugene N. Shearer,P.E. <br />i~~ <br />encl: Appendix - Calculations <br />Design of Open Channels <br />G\STE+~fi; <br />r. <br />V ' r ~:: <br />7 '-: .. <br />\\~ CFA.. ~~' <br />f <br />