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999 <br /> TUTTLE APPLEGATE, INC. _ <br /> Consultants for Land and Resource Development <br /> t <br /> February 4, 1991 <br /> `EB 0 5 199? <br /> Mr. Berhan Keffelew ki- ""Lan <br /> Mined Land Reclamation Division d <br /> 1313 Sherman Street, Room 215 <br /> Denver, CO 80203 <br /> RF: Idaho Creek Resource; Channel Design <br /> Dear Berhan: <br /> Attached with this letter is a copy of the spreadsheet calculations <br /> for the revised channel design. The new channel has a ten foot <br /> bottom width and 4 to 1 (H,V) side slopes. The velocities will be <br /> under five feet per second for the 10 year storm runoff and, <br /> therefore, erosion should not be a problem. <br /> The new channel will be excavated to a depth of 3 . 1 feet and a one <br /> foot berm will be constructed along both sides of the new channel <br /> to provide freeboard. <br /> _T have also enclosed a sketch of the existing Idaho Creek channel <br /> ups'treata and downstream of the relocated channel. The capacity of <br /> the relocated channel will have a slightly greater cross sectional <br /> area than the existing channel. <br /> Condition #2 of your approval letter asked for assurances that the <br /> ;cash water recycling ponds would not over-top during a 25 year, 24 <br /> hoer rainfall event. Such an event would generate 4 . 0 inches of <br /> rainfall . The third set of enclosures details how the ponds will <br /> accommodate this extra water. <br /> If there are additional questions, please give us a call. <br /> Cordially, <br /> TUTTLE APPLEGATE, INC. <br /> A45zvnA90_0t� <br /> Dave JWes <br /> DJ/cr <br /> FncL . <br /> File #91-156 <br /> Bill Kobobel <br /> 11990 Grant Street, #410 Telephone: ( 303 ) 452-6611 <br /> Denver, Colorado 80233 Facsimile: ( 303 ) 452-2759 <br />