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~ ±1 <br />• CLINTON W MEHAING, PRESIDENT <br />E. P. MIGM ELL. E:~EC. VICE Pw ESID ENT <br />D. D MELTON. VICE °P ESID ENt <br />A J. DEUTSC N, TRE45URER <br />J~ N. TU RN ER, SECPETAgY <br />TIPTON AND KALMBACH, INC. <br />I)TN AND MAgNET PLAZA. SUITE )00 <br />1]]I SEVENTEENTH STPEET <br />~ DENVER,COLORADO 80202 <br />PNONf 130]1 292~2T2) <br />N EAO OFFICE IN DENVER. COLO PGOO, SINCE 19]] <br />May 24, 1984 <br />Mr. James A. Kiger <br />Colowyo Coal Company <br />5731 State Highway 13 <br />Meeker, CO 81641 <br />Dear Mr. Kiger: <br />,I' <br />` Il I <br />~__ ~_-___.._J L...J <br />LVLV f~ I U L~J i~,~ ~. ~.i 1.1i 1. ... i <br />FOUNDEPS <br />ROYCE J. TIPTON (IE 9J~199T1 <br />OLIN BALM pACM 113U-~9T 91 <br />CABLE: ARTIP-DENVER <br />TW%: 010-931-2Sa0 <br />Subject: Sediment Confrol Design -Explosives Magazine <br />The two collection ditches adjacent to the explosives magazine and access road are <br />adequate to pass without overtopping the ten-year, 24-hour storm drainage. The <br />maximum slope of the ditch, 4.3~, may cause minor erosion in the ditch, but the small <br />volume of flow, 4.3 cfs, does not warrant erosion protection. <br />The 18" diameter CMP shown on Exhibit A and B is adequate to pass the peak <br />• runoff for the ten-year, 24-hour storm. <br />The existing ditch located below the culvert and adjacent to diesel storage tanks <br />should be lined with mine waste rock to prevent erosion. A two-foot wide, two-foot <br />deep, rock-lined trapezoidal channel would be adequate to pons the combined flow from <br />the two collection ditches. A recommended typical channel cross section is shown on <br />Sheet 9 of the enclosed calculations. Other cross section shapes could be used if the <br />trapezoidal shape is not convenient. <br />If we can be of further assistance, please do not hesistate to call. <br />Very truly yours, <br />TIPTON AND KALMBACH, INC. <br />Yv~ <br />Jerry Waugh <br />JRW/ty <br />Enclosures <br />i <br />