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'- - <br />~f: . <br />kerr coal company ~ . J ~- <br />;~ \\\ r~ <br />' boa =97 warden, comrado 80x80 ~ 303: 7234721 ~~ <br />' Da~?~: <br />' NL=. Patricia A. Ne_s.a <br /> Cclorado Departme~~ of Health <br />' Nater Quality Contrc: Division <br />-1210 East 11th Avenge <br /> D=_aver, Colorado 80220 <br />' Re, : KEii COAL COMPANY - ;'!~-c.R MINE ( PERMIT Nv . <br />COG-?50037) , REQUES': ?OA STORMWATER E7C~~":'.ON <br />.ear Ms. Nelson: <br />Kerr Cca: ~ompany (Kerr) owns and previously c~erated the <br />' Y3rr Mine, located approximately four=een miles east of ._e town of <br />icalden, Colorado. dining operatics ac the mine have c=_ased and <br />the :nine is curren..y in an active =ec_amation mode. D=:-image and <br />' sediment control fcr the mining rela.ed disturbance is p=cvided by <br />a number of engineered sedimentatio^ DOndS, collection/diversion <br />ditches, and assct_ated drainage st^sctures. Discharce from the <br />' sedimentation ponds is controlled and regulated under applicable <br />provisions of Pe-dt COG-850037, Discharge for t*e twelve <br />individual outfal_s•znder this permit comes almost exclus=rely from <br />~nowmelt runof°, wi.h no process water discharge and dis:.=arge from <br />~ rainstozms being rare. <br />All sed_-.entation ponds are designed and ma-=rained to <br />arovide a minimum de*_ention time of at least 24 hours _cr retained <br />runoff resulting ':om the 10 year, 23 hour storm event. While the <br />ponds are desigr.=_ co provide adec~~ate detention t~~~ to allow <br />settlement of suss=:ded solids, due :o the character'_s_ics of the <br />dominant soil tykes in this area both undisturbed a.~d disturbed <br />area runoff typ:ca:,ly have relat'_veiy high levels o' suspended <br />solids. In additic~, a relatively hi?h percentage of t`e suspended <br />solids in the r.:.-c~f are fine coi'_oidal materials wLich do not <br />readily settle o::. of suspension. <br />During ~ariods of high f:ow due to either :-cwmelt or <br />rainfall runoff, :~e noted factors combine to limit tie trapping <br />ef`_iciency of the ~~isting sedimentation ponds with the result that <br />concentrations o' certain parameters in pond discharge .:ay exceed <br />applicable eff:::e-~ limitations. The accompany ~ozitoring <br />=eport(s) indica== exceedance of effluent limitatic~s for the <br />°ollowing dischar_== point(s), eff:::e__^-t parameters(sf, a_ <br />~onitorina per_cd s; for wcich an eempcion is reques.e=.~ <br />