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<br />Remnant terrace gravel deposits cap the upland divide areas <br />in the vicinity of the proposed mine. These gravels were laid <br />down by the Canadian and Michigan River systems when they were at <br />that level. These gravel caps collect water that infiltrates as <br />a result of rain and snowmelt. This water then follows the grad- <br />ient between the gravel and the underlying consolidated sediments <br />and discharges along the sides of terraces as springs or seeps. <br />The seep adjacent to the mine site will not be disrupted by min- <br />ing activities. <br />The alluvial formation along Bolton Draw contains recent <br />surficial deposits, and serves as a potential groundwater <br />source. However, no alluvial gravels derived from the older <br />terrace gravels are present in the headwaters region of Bolton <br />Draw, which is above the confluence of the North and Middle Forks <br />of Bolton Draw. Mining disturbances will occur mainly within the <br />North Fork, where some sediments will be removed during mining. <br />These sediments occur updip from the nose and flanks of the anti- <br />cline and are exposed along the crest of the structure. As dis- <br />cussed in the mine plan, however, recharge to this system is <br />solely from precipitation events. Water that enters the exposed <br />sediments migrates down dip towards deeper areas in the basin. <br />This flow should be minimal due to low average annual precipita- <br />tion (11 inches), sloping topography that promotes surface runoff <br />rather than infiltration, and the nature of the underlying Coal- <br />mont Formation (highly interbedded and lenticular)which greatly <br />retards any water entering the recharge area. The alluvial <br />deposits of the Bolton Draw are discussed in more detail in the <br />AVF section of this TEA. <br />The applicant has presented suitable quantification of the <br />amount of groundwater that will be intercepted during mining. As <br />stated previously, this amount should be minimal. Impacts to <br />groundwater flow were quantified by determining the cross-sec- <br />tional area of the aquifers to be intercepted by mining and <br />utilizing the permeabilities (flow rates) of these aquifers. <br />-79- <br />