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There is no evidence of surface runoff in the vicinity of the <br />site. Essentially all precipitation apparently infiltrates <br />the highly permeable mantle of sand. No water-formed <br />erosional features are evident, not even small rills or <br />gullies. Ennis Draw is a broad, flat-bottomed depression with <br />no observable channel or gully and shows no evidence of the <br />existence of aur£ace flows. <br />The thickness of the blow sand overlying the Laramie is <br />variable but is sufficient to hold a large quantity of <br />capillary water. Thies observation, coupled with the small <br />annual precipitation relative to the potential <br />evapotranspiration, makes it unlikely that significant <br />recharge to the Laramie through the sand exists. This sand is <br />not known to yield water to wells except in conjunction with <br />the stream deposits in Ennis Draw. <br />Subsurface water occurrence in the coal seem of interest and <br />in the overburden are isolated. Lateral movement of this <br />water is toward the northeast in the mine area and may <br />discharge into the sands and stream deposits in Ennis Draw to <br />the north and east of the mine site. Observations of the coal <br />seam indicate only a saturated thickness of 1 to 2 feet at an <br />elevation well below that of the piezometric water surface of <br />Ennis Draw. This suggests that water occurrence in the coal <br />seam is confined and no hydrologic connection exists between <br />the coal seam and Ennis Draw. Ground water in neither the <br />coal nor overburden is known to provide a water supply for any <br />purpose in the vicinity of the mine. Refer to Piezometric <br />Surface Map, Map 4.6.3 (e) <br />Subsurface Water Hydroloay <br />Four subsurface water systems can be identified to exist in <br />the vicinity of the project site. In order of occurrence Ctop <br />to bottom) they are situated as follows, 1) wind blown sand <br />and fluvial deposits in and adjacent to Ennis Draw, 2) <br />weathered betlrock (transition) zone consisting of silty clays <br />and sands, 3) unweathered, overconsolidated clays and clay <br />shales, mud atones, clay stones, coal and minor sandstones of <br />the Laramie Formation (excluding the lower Laramie sends) and <br />4) the Laramie-FoxHil}s aquifer (which includes the lower <br />Laramie and Fox Hills $andstone formations>. <br />Information regarding ubsurface water occurrence is <br />summarized as follows refer to cross sections on following <br />pages, where aquifer s stems are labled by number): <br />• <br />-25- <br />