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<br />R. G. OTTO & ASSOCIATES <br />~'.: <br />Results: Ground Water Assessment. The influence of percolation <br />that might occur through the west waste rock pile oa ground water <br />quality 8ownslope of the pile was evaluated by compari~aq surface <br />water quality upslope of the pile with the chemical water quality <br />at Cotter Well *4 (Figure 4). Percolation into or through highly <br />mineralized soils of the types that characterize the Ralston Creek <br />drainage would be expected to have an immediate, signir"icant <br />effect on the chemical quality of surface waters and tl~e results <br />of these comparisons are as anticipated (Table 3). Ground waters <br />collected from Well iF4 had markedly higher conductivities <br />(dissolved solids concentration) and sulfate concentra~Gions than <br />did surface waters upslope for all sampling periods. 'Che pH was <br />depressed accordingly. Soluble uranium, copper, lead, boron and <br />radium-226 concentrations were also measurably elevated in the <br />ground water (relative to the paired samples collected <br />concurrently from the stream). <br />The remaining parameters were consistently at or below the <br />analytical detection limits at both sites. In summary, the <br />observed differences in water quality all are in accord with <br />expectations for changes in water quality following pe:rcolatioa <br />through naturally mineralized soils. Given the concer~i for <br />effects of ground water intrusions on surface water quality of <br />Ralston Creek, it is especially pertinent that, of the parameters <br />measured in the ground water, only copper levels exceeded the <br />Colorado Water Quality Standard. <br />^n <br />