2019-02-13_HYDROLOGY - M2012032 - Laserfiche WebLink

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DIJRAY SILVER MINES FEB 13 2019 Dint"OF RECLAMATION MWM AW SAFETY February 12,2019 VIA tl,S,Mail and Email _._ Travis Marshall, Environmental Protection Specialist ?01- Colorado Division of Reclamation,Mining,and Safety 1313 Sherman Street, Room 215 Denver,CO 80203 RE: Passive Treatment Pilot Test Materials Handling Ouray Silver Mines Inc.(OSMI)owns and operates the Revenue-Virginius approximately 6 miles south west of Ouray Colorado under the Colorado Division of Reclamation,Mining,and Safety(DRMS)permit number M2012-032(Permit). OSMI recently performed an underground Passive Treatment Pilot Test to permit a five-stage passive treatment system with CDPHE. This letter discusses the characteristics of materials used,the leaching results,and requests permission to combine the pilot testing material with the topsoil stock pile. The pilot test consisted of two parallel trains(A and B).The materials incorporated at each stage of these parallel trains is described below.All materials were commercially sourced_ • Transitional Aerobic Wetland:two 55-gallon barrels containing 7 cubic feet each of sand and gravel • Sulfate Reducing Bioreactor(SRB):two 2,500-gallon tanks contain 5%manure, 30%wood trips; 15%hay/straw,20%limestone,and 30%gravel • Anaerobic Wetland:two 275-gallon containers(approximately 36 cubic feet each)of 30%wood chins;50%sand,5%manure; 15%hay/straw and 30%gravel. • Aerobic Wetlands:four 55-gallon barrels(7 cubic feet each)of 75%sand and 25%gravel During the construction of the sulfate reducing bioreactors, materials were loaded by hand into the large 2,500-gallon from stockpiles placed in the crusher area.As a result,small amounts of ore were accidentally incorporated into the bioreactors,particularly near the top(as the floor of the crusher gallery was encountered last during loading). Early effluent from the system showed an increase in metals(particularly lead)over influent water that has been attributed to the incorporation of the small amount of ore from the floor during the loading process. Once the sulfate reducing bioreactors became reducing effluent metals concentration dropped in comparison to influent meeting industrial wastewater discharge standards when the test was terminated.The ideal functioning of the test at the time of termination indicate that the materials are not spent. PO Box 564, 1900 Main Street,Unit 1,Ouray,Colorado,USA 81427 Tel. 970-325-9830—Fax. M-325-9824