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~ Wesl Elk Coal Company, Inc. <br />Post Office f3ox 591 <br />. Somerset. Colorado 81434 <br />Telephone 303 929 5015 <br />:..tl '~ <br />- ~ ~. ~h~ <br />III IIIIIIIIIIIII III <br />JUN 19 i986 <br />June 13, 1986 <br />r,; ,. ,.. ,,, <br />.;.~, ~.~.r _. .d ., .... ., <br />~..^-I!'. ~i~~; e~. tai ~~" ..:"! !?~S;l. a: a:. <br />Mr. Robert Liddle <br />Colorado Mined Land <br />1313 Sherman Street <br />Denver, CO 80203 <br />Dear Bob: <br />Reclamation Division <br />As you are aware West Elk Coal Company (CMLRD Permit <br />C-007-80) has been having maintenance and operational <br />problems with the infiltration underdrain dewatering <br />system installed in sediment ponds MB-1 and MB-2. <br />This problem causes no environmental problems; however, <br />it causes maintenance and operational problems because <br />the ponds require pumping occasionally. WECC plans <br />to correct this problem by installing a gate valve <br />in the control tower of each pond near the pond bot- <br />tom elevation. Necessary reinforced concrete wing <br />walls as well as a baffle to keep sediment from <br />entering the valve area will also be installed. This <br />valve will not interfere with the normal dewatering <br />outlet located in the tower. The lower valve will <br />be equipped with a manually adjustable height skimmer <br />consisting of a flexible rubber or other suitable hose <br />to maintain the discharge above the sediment level of <br />the ponds. See attached drawings for detail. <br />During precipitation events the normal dewatering <br />outlet will be used to dewater the 10 YR, 29 HR <br />precipitation event runoff as required by the regula- <br />tions. <br />The installation of the lower valve is a maintenance <br />item being performed in lieu of repairing the under- <br />drain system. Repair of the underdrain system is <br />extremely costly and the effectiveness and reliability <br />of the underdrain system due to design considerations <br />is very poor. <br />The enclosed drawings (revised) are located in the <br />~'1' /..-e~~ ~le AMCO-o20s <br />/ ~~ ~ <br />