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/ `, - <br />Mountain Coal Company <br />West F.Ot Mtris <br />PQ~o..d. Oflke Bmt 591 <br />TdapMns 303[Q9.5015 <br />Fex 303 995596 <br />May 7, 1996 <br />Ms. ICatheen Sullivan <br />Permits and Enforcement Section <br />Colorado Departrnent of Public Health and Environment <br />Water Quality Control Division (WQCD) <br />4300 Cherry Creek Drive South <br />Denver, CO 80222-1530 <br />'~' <br />R~•rFIVEi~ <br />~Y 1 p 199fi <br />~'~~sron or Mmerars ~ Geology <br />III IIIIII'll llll 111 <br />c <br />~ ~A,1 <br />Re: Mountain Coal Company, West Elk Mine, CDPS Permit No. CO-0038776, Whole <br />Effluent Tozfcity (R'ET) Testing Change Request <br />Dear Ms. Sullivan: <br />As we discussed in our telephone conversation May 07, 1996, Mountain Coal Company is <br />providing a written request to follow-up on your verbal approval today for a change in the WET <br />Testing parameter for the mine water bypass discharge that would be piped to the emergency <br />spillway for Ponds MB-1 and FW-1, (Discharge Points 002 and 006). The request is to use <br />Daphnia magna as the test species for whole effluent testing at this mine dewatering bypass <br />discharge location. All other pazameters would remain the same as for Discharge Point 002. <br />The request is necessary and prudent in allowing Mountain Coal Company (MCC) to directly <br />discharge mine water to the North Fork of the Gunnison River when it meets all other parameters. <br />In the past, the quality of the mine water discharge was being contaminated by mixing it with <br />stormwater mm~off in the ponds (IvIB-1 and MB-2R). This would increase the volume of water <br />and the total suspended solids (from mixing) in the water, which became a maintenance intensive <br />situation for MCC in order to meet the dischazge limitations. The mine water meets the discharge <br />limitations with exception to the Ceriadcrphnia dubia populations in the WET Tests. Mountain <br />Coal Company has conducted testing with Daphnia magna and found that no toxicity (LC50) <br />was apparent in this test species at the 100 % concentrations of effluent. The fathead minnow <br />populations survived in both tests at all concentrations of effluent. The results of tests utilizing <br />both CeriodapTnia dubia and Daphnia magna are attached for your review. <br />