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Non-Tributary Support: Cash Mine Borehole AdrianBrown <br />Peak Withdrawal Rate when Pumping: 50 gpm <br />The permit application uses the Peak Withdrawal Rate when pumping. <br />4.4 Lack of Material Injury <br />4.4.1 Diminution of Service <br />The injury that the extraction will cause has been evaluated using superposition of computed drawdown <br />due to mine dewatering to the current level of approximately 317 feet below ground surface. The extent <br />of drawdown is computed from the area required to provide 1.56 gpm of flow assuming an infiltration <br />rate of 0.78 inches per year. The resulting groundwater elevation.is illustrated in Plate 3. Also shown is <br />the surface elevation; the.pre-mining head is in general approximately 50 feet below ground surface. <br />As can be seen from this evaluation, the drawdown impacts reach out an average distance of 733 feet <br />from the well (although the drawdown is centered on the mine, not the dewatering well). At any location <br />within this affected area, groundwater is available by drilling to a greater depth than the water table, <br />which currently varies from 50 to 317 feet below ground surface. As by statute, "(t)he reduction of <br />hydrostatic pressure level or water level alone does not constitute material injury. " (Section 37-90-137 <br />(7) C.R.S.), no material injury occurs even within this affected area. <br />Locations of known points of groundwater extraction were downloaded on October 30, 2006 from the <br />well files of the Colorado State Engineer, Division of Water Resources, State of Colorado24. A total of <br />five wells were identified within the surface water watershed of the mine (an area bounded by Skillet <br />Gulch to the west, the ridge to the north, Blackhawk Gulch to the east, and Gold Run to the south). <br />Information on these wells is presented in Table 1, and they are located on Plate 2. Of these wells, the <br />closest is 953 feet from the Cash Mine Borehole, and this is a monitoring well for the Gold Hill Mill. <br />The nearest water supply well is 1,974 feet west of the Cash Mine Borehole, on the outskirts of Gold <br />Hill, and outside any influence of the dewatering of the mine. <br />24 http://165.127.23.116/website/Ittools/index.asp?iw=800&ih=600, last updated 10-1-2006. <br />1601A-20070125 12