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4. Evaluation of the fate of any leachate in the environment. <br />This procedure is in accordance with Mineral Rules and Regulations of the Colorado Mined Land Reclamation <br />Board for Hard Rock, Metal and Designated Mining Operations (HRMMR) Section 6.4.20(14), which requires <br />both geochemical analyses of the rock and evaluation of the fate of the material under conditions that are <br />reasonably expected to prevail after mining and reclamation have ceased. The Sunday Complex and Van 4 <br />mines are located in an and environment where evaporation greatly exceeds precipitation. Therefore, it is not <br />appropriate to draw definitive conclusions from initial screening of MWMP data. However, the data are useful <br />to screen the concentrations of potential contaminants in the MWMP extract solution in relation to Colorado <br />Ground Water Quality Standards. <br />In order to provide this initial screening, the MWMP analytical results were compared to water quality criteria <br />provided by CDPHE Water Quality Control Commission4 for domestic water supply (human health), domestic <br />water supply (drinking water), and agricultural standards. The following summarizes the results of this analysis <br />for each screening criteria. <br />? Some samples were above the domestic water supply (human health) standards for antimony, arsenic, <br />cadmium, gross beta, fluoride, lead, molybdenum, nitrogen (nitrate as N), nitrogen (nitrate + nitrite as <br />N), nitrogen (nitrite as N), selenium, and uranium. <br />? Some samples were above the domestic water supply (drinking water) standard for chloride, sulfate, <br />and pH. <br />? Some samples were above the agricultural limits for arsenic, copper, fluoride, lead, nitrogen (nitrate + <br />nitrite as N), pH, selenium, and vanadium. <br />The present status of the groundwater in the Sunday Mines region is unclassified (still evaluating the Van 4). It <br />is currently undetermined which of the three standards would be applied in this case, so all three are discussed <br />above. Work is in progress on the remaining three steps of this analysis. <br />Potential for rock to be acid-forming <br />The potential for the rock to be acid-forming is evaluated by acid base accounting and comparison of MWMP <br />extract pH to the pH criterion of 5.8 set forth in Colorado Regulations for Hard Rock, Metal and Designated <br />Mining Operations Section 1.1(2). The ABA data for the samples is presented in Figures 1 and 2, which <br />indicate that the samples are not acid forming. The ABA data support field observations of no visible sulfide <br />minerals and a ubiquitous presence of calcite in the samples. Extract pH from the MMWP tests are all higher <br />than the 5.8 threshold, which also supports the conclusion that the rock is not acid-forming. <br />Groundwater Well Installation <br />Groundwater monitoring wells were installed to provide information on ambient groundwater quality and to <br />evaluate potential effects of underground mining on water quality. Four monitoring wells were installed in the <br />West Sunday Mine during the week of December 15 in accordance with the groundwater work plan. These <br />include 1 upgradient well and 3 downgradient wells. <br />Some field modifications to the design were necessary because of site specific conditions. These modifications <br />include reducing the planned depth of the wells in response to difficulty in drilling, modifying the planned <br />location of the wells slightly due to site-specific conditions, and not installing one background well because the <br />area of the mine had dried up due to continued mine ventilation. <br />4 Colorado Groundwater Standards were obtained from Colorado Department of Public Health and Environment (CDPHE) <br />Water Quality Control Commission, 5 CCR 1002-41, Regulation No. 41, Tables 1-3, The Basic Standards for <br />Groundwater. <br />A 9 <br />DENISONO:'4"" <br />MINES <br />3