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17J <br />Probable Hydrologic Consequences New Elk Mine 7 <br />era <br />�•�wm <br />:wM „r rM <br />.ww Mu.I,•w.Mar,s.M...iw.. <br />• Su.e.mn nei.5a x.nvWn o.me..nan,m'nw 0 5 5 ,0 IS A 11 9MM MILES <br />h <br />Figure 3. Generalized Configuration of the Long-Term Water Table in the Northern Portion <br />of the Raton Basin (Watts, 2006a) <br />3.1.1 Alluvial Aquifer <br />Alluvium and unconsolidated sediments are present along the valley floor adjacent to the Purgatoire River <br />and are an important source of domestic and agricultural water supply for area residents. Drilling records <br />from the Colorado Department of Water Resources (CDWR) indicate that the alluvial thickness may <br />exceed 70 feet in some areas, but most wells access groundwater from alluvium that is less than 30 or 40 <br />feet thick. WWL (1980) drilled eight boreholes in alluvium new the permit area and concluded that <br />groundwater was present only in alluvium that was in direct hydraulic connection with the Purgatoire <br />River, and that the thickness and extent of the alluvium is limited. Three of the boreholes were drilled new <br />the Allen Mine. The remaining five boreholes were installed new the Maxwell Mine. <br />The extent of unconsolidated deposits including alluvium, colluvium, and terrace gravels has also been <br />mapped in Apache and Ciruela Canyons (Wyoming Fuel Company [WFCj, 1985). The deposits are <br />generally thin and are narrowly confined along the canyon floors. Alluvium in the upper reaches of the <br />drainages is unsaturated or may be seasonally saturated during spring mnoff. Alluvium in the lower <br />reaches of the canyons near the Purgatoire River is saturated. <br />Groundwater levels in alluvium are available from boreholes that were installed by WWL (1980), from <br />well records that were obtained from CDWR, and from monitoring wells located new the East Portal Shaft. <br />WWL reported that the depth to water in the Purgatoire Valley Alluvium ranges from 4 to 6 feet below <br />ground surface (bgs) and that groundwater levels are largely controlled by the river level. Well records <br />from CDWR indicate that water levels in the alluvium range from 3 to 15 feet bgs (Table 4). Locations <br />• <br />4164A. 110130 µ'Mtrawrebrx/ibt� <br />PR 02 Exhibit 8(4) Page 128 Revised 1/31/11 <br />