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<br />kerr coal company <br />001 .[e] M~IdM, COIOfWO $~~ IjQj~ 714721 <br />Date: Y <br />Ms. Patricia A. Nescn <br />Colorado Departmenr of Health <br />water Quality Control Division <br />4210 East :ith Aven_s <br />Denver, Colorado 20220 <br />"f~i <br />..4'd"- <br />i:' .. <br />/ ,S~ <br />~~ . <br />RE : KFicic COAL COI~ANY - I~91RR I~IINfi ( PERI'~T N0. <br />COG-350037), REQIIEST FOR STORMWATER fiXF.~LaT_ON <br /> <br />Deer Ms. Nelsoa: <br />Kerr Coa_ Company (Kerr) owns and previously ozerated the <br />M3r-_ Mine, located aporoximately fourteen miles east of t e rows :.f <br />Walden, Colorado. Mining operations at the miss have ceased and <br />the :nine is curren..y in an active reclamation mode.. Drainage sad <br />sediment control for the miniag related disturbance is provided ay <br />a number of engineered sedimentation ponds, collection/diversion <br />ditches, and asscc:ated drainage structures. Discharge 'rte the <br />sedimentation ponds is controlled sad regulated under appi:_abia <br />provisions of Pe~i.t COG-850037. Discharge for the twelve <br />individual outfalls:iader this permit comes almost exclusively Etta <br />srowmelt runoff, wiry ao process water discharge and discaa.-ge from <br />rainstorms being :are. <br />All sedimentation ponds are designed and mainta-:ed ro <br />provide a minimum detention time of at least 29 hours far retained <br />runoff resulting ..om the 10 year, 2a hour storm event. While the <br />ponds are designed to provide adeeuace deteatian time co allow <br />settlement of suspended solids, due to the characteristics of the <br />dc~inanc soil types in this area both undisturbed and disturbed <br />area runoff typically have relatively high levels of suscended <br />solids. Ia addit.ca, a relatively high perceacage of the s•.=_~ded <br />solids in the ru~o.E are fine colloidal maceriala which do not <br />readily settle out of suspension. <br />During :eriods of high flow due to either snowmelt or <br />=ainfall runoff, the noted factors combine to limit the t=apping <br />e*":icienrt of the =eiscing sedimentation ponds with the rasu?t that <br />concentrations of certain parameters in pond discharge caay exceed <br />applicable efflLett limitations. The accompany monitoring <br />.snort(s) indica.e e.YCeedance of effluent limitations for the <br />:allowing discharge point(s), efflue.^.t paramecers(s), sad <br />^cnitor:na pericd.s; :or which an =.re.^.sptien is request=.'. <br />