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<br /> <br />' On January 30, 1986, the Colorado Division of Minerals and Geology (CDMG) approved a <br />Technical Revision to reduce the hydrologic monitoring program at the site. Stations associated <br />' with the Revision Area No. 2 in Deep Creek (DC-1, W-17 and W-18) were not required to be <br />monitored by the current program; the water quality parameters of arsenic, cadmium, lead, <br />mercury, molybdenum and selenium were eliminated from all stations except well W-16 located <br />' in the reclaimed area of the east pit; water quality sampling of the Stollsteimer Creek alluvium was <br />added to station A-1 and eliminated from station W-1; and frequency of sampling, depth-to-water <br />measurements, and stream discharge measurements were not changed by this revision. In June <br />1988, the CDMG approved a technical revision to conduct this monitoring program on a quarterly <br />basis and in May 1990. a technical revision was approved which eliminated all groundwater <br />' monitoring at the site and all monitoring wells were reclaimed. In January 1992, the CDMG <br />approved a reduction in surface water sampling to quarterly flow measurements and semiannual <br />water quality at three surface stations. In early 1993, a decision was made to resume alluvial <br />' aquifer monitoring and in late summer, wells A-1, W-1 and W-5 were reinstalled for the purposes <br />of this monitoring. Groundwater in bedrock aquifers were not resumed because the analysis of <br />the probable hydrologic consequences of mining impacts indicated that no further potential impacts <br />would occur. A Phase II bond release was approved and the pond and ditch sediment control <br />system was reclaimed in the fall of 1997. The CDMC also approved TR-30 which suspended <br />surface and groundwater monitoring until two years prior to a Phase III release application. <br />1 The following sections of this report describe the methods and results of the hydrologic monitoring <br />program conducted at the Chitnney Rock Mine site during 1997. Also contained in this report is <br />' a comparison of the data collected over the 1985 through 1997 period and recommendations for <br />future monitoring. <br />1 <br /> <br />1 <br /> <br />1 <br /> <br />1 <br />' 1997.053/3/01-1698(S:I7am) <br />