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0 STATE C COLORADO <br /> .DIVISION OF MINERALS AND GEOLOGY <br /> I)rp.inm,•nl of Natural RCSourCeS <br /> I f I {Shaman A., Room 215 <br /> 0,,w.r.('nloradu 80203 <br /> I'honr:(N171%LD-S567567 <br /> fAX HO t)11;I 11106 ;1 <br /> DEJ ARTNIENT OF <br /> NATURAL <br /> DATE: January 6, 1997 RESOURCES <br /> TO: Carl Mount Ru, Ronvv, <br /> FROM: Harry Posey nnr <br /> AIA-1 S.I,a hh. l <br /> RE: Review: Modified SPLP Test Results,Joker Mine, Sleeping Giant Projedk;'° u n <br /> Northwestern Colorado, Permit No. M-83-052 %1"had H.Lnn, <br /> D..w,,n DirrUur <br /> The cited report compares the leach test results of four samples to various standard measures and <br /> concludes that weathering of the leached materials poses no threat to groundwater. <br /> Knight-Piesold evidently understands that the state of the industry with regard to testing shows <br /> that there is no single, simple test whose results can be used as a direct indicator of potential <br /> environmental consequences. Thus,they elected to modify both the existing SPLP analytical <br /> procedure as well as the reporting procedures. In that regard, I have no significant criticism of <br /> how they modified both the testing procedures and the analytical results. <br /> A procedure that is useful to DMG is where leach tests are interpreted with due regard to ore and <br /> waste rock mineralogy, physical handling procedures (size gradation of ores vs gradation of test <br /> samples), chemical treatment procedures, and local climatic and hydrologic conditions. Rather, <br /> the results were compared with several water quality standards. Because DMG's approach is <br /> not standards-based, such standards-based comparisons, while indicative, are not definitive. <br /> Operators sometimes find it useful to take account of chemical attenuation, dilution, and other <br /> post-discharge chemical effects that may enhance or lower the concentrations of materials of <br /> environmental interest. <br /> There are significant differences between the analytical results for the LOC-treated samples and <br /> the leach residues that are not explained in the report. The permit file does not explain the <br /> treatment process, so I cannot deduce accurately why the analyses appear as they are; however, <br /> some interpretation is required. <br /> 1. Evidently, some acid either in the rock or the treatment process uses up calcite and dolomite. <br /> and yields a residue that produces a lower pH than the original rock. <br /> 2. Nitrogen components decrease while Na, TDS and some of the radionuclides increase. This <br /> does not appear to comport with gravity separation processes that are described in the permit <br /> documents. <br /> 3. Given the complimentary increase in Na and Cl, it seems feasible that alkaline chlorination <br /> may be involved; however. the latest revisions to the permit indicate that the operation will not <br /> use chemicals that could make the operation a DMO. Perhaps this issue needs to be addressed <br />