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~_ <br /> <br />DIVISION OF MINERALS AND GEOLOGY <br />Depanmem or Natural Resources <br />1 J 13 Sherman St., Room ? 15 <br />Denver, Colorado 80207 <br />Phone: IJ03) 866-3567 <br />FAX: (303)A32-A106 <br />February 6, 1998 <br />~ iii iiiiiiiiiiiiiii <br />c-re-rt OF COLORADO <br />~I~~~ <br />DEPARTMENT OF <br />NATURAL <br />RESOURCES <br />Roy Rnmer <br />Governor <br />lames S. Lochhead <br />TO: Larry Oheler Executive Director <br />Michael B. Long <br />Division DueUOr <br />FROM : Berhan Keffelew <br />RE: File # M-97-054, Adequacy Items <br />Per your request, I have reviewed the surface and Ground Water responses under Exhibit "G" <br />a~3d parts of your adequacy questions under exhibit" C". <br />SURFACE WATER <br />The operator provided as requested by the Division , a detailed watershed design for 75 sub- <br />basins covering 287 square miles. <br />The crossing designs ,storm water berms and ponds were designed to Handle the 100 year 24 <br />hour storm event plus .5 inches of rain for added safety margin for permanent structures and a 10 <br />year 24 hour storm event plus .5 inches of rain for the added safety margins for temporary <br />structures. <br />1 recommend the operator mark the granite and sandstone 100 year 24 hour PPT. Ponds to show <br />where the 50% sediment storage area will be and clean the ponds when they reach that level <br />prior to adding additional sediment. In the narrative, it is only stated that the ponds will be <br />cleaned on frequent basis. If [hey want to recommend a frequency, we might accept that <br />depending on how the frequency is based upon. Both temporary and perntanent structures can <br />safely pass the 10 year and 100 year PPT. events as designed. <br />The two Tallahassee Creek crossings will be subject to Army Corps of Engineer approval and <br />will also be covered under CDOH&E Water quality general storm water Discharge Pennit. <br />The Tallahassee Creek 100 year flood plain area was properly provided with the appropriate <br />cross-sections showing the maximum reaches. <br />WATER QUALITY <br />The concerns raised by the citizens regarding water quality were addressed by the operator by <br />sampling water from five surface water discharge and five from ground water sources. Attention <br />was given to heavy metals ,Arsenic and hydrogen sulfide. The operator explored for sulphide <br />