Laserfiche WebLink
1 <br />kerr coal company <br />hox .t87 ~ warden, cotorado BOS80 ~ 13031 723-0721 ~ ~'~ <br />Date: ~~ <br />' Ms. Patricia A. Nelson <br />Colorado Departure^t of Health <br />Water Quality Control Division <br />4210 East 11th Avenue <br />Denver, Colorado 80220 <br />' RE: KERB COAL COMPANY - MP.RR MINE (PERMIT N0. <br />COG-950037), REQUEST POR STORMWATER EXII~TION <br />_ Dear Ms. Nelson: <br />~ Kerr Coal Company (Kerr) owns and previously operated the <br />Marr Mine, located approximately fourteen miles east of to tcwn of <br />J Walden, Colorado. Mining operations at the mine have ceased and <br />the mine is currently in an active reclamation mode. Drainage and <br />sediment control for the mining related disturbance is provide3 by <br />a number of engineered sedimentation ponds, collection/diversion <br />ditches, and associated drainage structures. Discharge from the <br />sedimentation ponds is controlled and regulated under applicable <br />l provisions of Permit COG-850037. Discharge for the twe:ve <br />1) individual oucfalls under this permit comes almost exclusively fr~:n <br />snowmelt runoff, wi*_h no process water discharge and discharge from <br />l rainstorms being rare. <br />l All sedimentation ponds are designed and maintained to <br />provide a minimum detention time of at least 24 hours for retained <br />runoff resulting from the 10 year, 24 hour storm event. While the <br />ponds are designed to provide adequate detention time to allow <br />settlement of suspended solids, due to the characteristics of the <br />1 dominant soil types in this area both undisturbed and disturbed <br />area runoff typically have relatively high levels of suspended <br />solids. In addit_cn, a relatively high percentage of the suspended <br />1 solids in the runoff are fine colloidal materials which do not <br />readily se*_tle out of suspension. <br />During periods of high flow due to either snowmelt or <br />rainfall runoff, the noted factors combine to limit the trapping <br />efficiency o: the existing sedimentation ponds with the result that <br />concentrations of certain parameters in pond discharge may exceed <br />applicable effluent limitations. The accompany monitoring <br />report(s) indicate exceedance of effluent limitations for the <br />following discharge point(s), effluent parameters(s), and <br />monitorinc period s) for which an exemption is requested. <br />