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<br />kerr coal company <br />eo. a97 ~ w4We~. W1aWO 80490 ~ 13071 7Z3~7a1 <br />Dur ~~! <br />Ms. Patrida A. Nelson <br />Colorado Department of Health <br />Water Quality Control Division <br />4210 East 11th Avenue <br />Denver, Colorado 80220 <br />Rr. Kerr Coal Company • Mur Mine (Permit No. COG-8S0021~ Request for Stormwater <br />Exemption <br />Deu Ms. Nelson: <br />~J <br />Kerr Coal Company (Kerr) owns and previously operated the Mur Mine, looted approximately <br />founeen miles east of the town of Walden, Colorado. Mining operations at the mine have <br />ceased and the mine is currently in an naive reclamation mode. Drainage and sediment control <br />for the mining «lated disturbance is provided by a number of engineered sedimentation ponds, <br />collection/diversion ditches, and associated drainage structures. Dischuge from the <br />sedimentation ponds is controlled and regulated under appliable provisions of Permit COG <br />850021. Dixhuge for the twelve individual outfalls under this permit coma almost exclusively <br />from snowmelt runoff, with no proceu water dischuge and dischuge from rainstorms being <br />rare. <br />All sedimentation ponds ue designed and maintained to provide a minimum detention time of <br />at least 24 hours for retained runoff resulting from the 10 yeu, 24 hour storm event. While the <br />ponds ue designed to provide adequate detention time to allow settlement of ruspended solid; <br />due to the charaaeristict of the dominant soil typo in this aces both undisturbed and disturbed <br />aces runoff typially have relatively high levels of ruspended solids. 1n addition, a relatively high <br />percentage of the ruspended solids in the runoff ue fine colloidal matuials which do not radily <br />settle out of ruspemion. <br />During periods of high flow due to eithu snowmelt or rainfall runoff, the noted faaon <br />combine to limit the trapping effldenry of the existing sedimentation ponds with the result that <br />concentntiom of certain puameters in pond dixhuge may exceed appliable effluent <br />limitations. The uwmpanying monitoring report(s) indiate e:ceedance of effluent limitations <br />for the following dixhuge point(s), effluent puameter(s), and monitoring period(s) for which <br />an ezemption is requested. <br />Dixhugs Point Puame ter(sl Exceedin~Limitation Dixhuge Rate(~sl Dase(s1 <br /> <br />.;t0% ~ ~ /~ Gam' e' ~ <br />• <br />