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'`~" /V1S0~1ERSET <br />M/N/NG COlIi1PA N Y <br />May 12, 1995 <br />Kathleen L. Suiiivan <br />Colorado Department of Health <br />Water Quality Control Division <br />Permits and Enforcement Section <br />WQCD-PE-B2 <br />4300 Cherry Creek Drive South <br />Denver, CO 80222-1530 <br />iii iiiiuiiiiiu iii <br />'- \.. <br />~FCFIVFD <br />MAY 15 1995 <br />Division of rvunerals & Geology <br />RE: Aquatic Impairment Study and WET Testing <br />CDPS Permit No. CO-0000132 <br />Dear Ms. Suiiivan: <br />In response to your letter of April i0, i995, copy enclosed, <br />Somerset Mining Company conducted some additional testing through <br />Commercial Testing & Engineering Co. Testing was done with the <br />advice and consultation of Ms. Carla J. Castle of CT&E at 4665 <br />Paris, B-200, Denver, Colorado 80239, telephone (303) 373-4772. <br />Samples of the effluent from discharge point 011 were tested by a <br />modified acute WET test to remove only the TDS from the effluent <br />prior to testing by aeration, as suggested by the CDOH letter. <br />Aeration was not effective in removing the TDS, and the tests <br />failed the WET test criteria. <br />Additional samples of the effluent were tested by a modified acute <br />WET test to remove only the TDS from the effluent prior to testing <br />by lowering the alkalinity by titration with suifur~c acid, as was <br />done for the initial Toxicity Identification E•~aluat;on (TIE), <br />October 19, 1992, copy of the report enclosed. Results of the <br />modified acute WET test passed the tggm Last cri*_eria with <br />ceriodaphnia dubia. <br />The source of the alkalinity in the effluent has been identified as <br />groundwater inflow into the mine as documented ;n repor±s dated <br />October 26, 1992, August, 1993, and October, 1993, copies enclosed. <br />Somerset Mining Company has chosen Option i from the April 10, 1995 <br />letter, and proposes a modified acute WET test by lowering the <br />alkalinity by titration Wlth sulfuric acid, and testing with <br />ceriodaphnia dubia. <br />P.O. Box 535 7901 Southpark, Suite 202 <br />Somerset, CO 81434 Littleton, Co 80120 <br />(303)929-5122 Fax (303)929-5177 (303)795-0413 Fax (303)795-1524 <br />