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-8- <br />The Upper Coal member is approximately 220 feet thick, containing shales, <br />siltstones, sandstones, and the "D", "E", and "F" coal seams. The mine will <br />be located in the lowermost seam, the "D" seam. At the mine site, the coal <br />is immediately overlain and underlain by shale. See Map 2-10, "Representative <br />Statigraphic Column, Coal Member, Mesaverde Formation, in Volume 2. The "D" <br />seam overburden ranges from approximately 500 feet to 2,000 feet within the <br />permit area. The thickness of this seam decreases from 26 feet at the outcrop <br />to 8 feet at the northern edge of the permit boundary. The "D" seam dips from <br />the outcrop area in the South five degrees to the North, and the strike is <br />North 88o West. <br />Overlying the upper Coal member is the Barren member of the Mesaverde <br />Formation. This unit consists of interbedded and lenticular sandstones, <br />siltstones, and shales of varying thicknesses. This unit is thought to be of <br />terrestrial origin and, as a result, the sandstones and the coals are highly <br />lenticular, discontinuous, and of limited lateral extent in outcrop. This <br />unit ranges up to 1,600 feet thick and outcrops throughout the southern <br />portion of the permit area. <br />Three categories of potential aquifers occur in the general area. These are <br />alluvial and terrace deposits associated with the North Fork of the Gunnison <br />River, the localized shallow alluvial/colluvial areas in the stream drainages, <br />and ground water in the lenticular sandstones and the Rollins sandstone of <br />Mesaverde Formation. <br />The most significant occurrence of ground water in the general area is <br />associated with the alluvium of the North Fork of the Gunnison River, located <br />approximately 2 miles southeast of the mine portals and 1,500 feet lower in <br />elevation. Significant alluvial sand and gravel deposits averaging 34 feet <br />thick exist along the North Fork from the mouth of Terror Creek to the <br />confluence of the Gunnison River. There are numerous wells in the area which <br />draw water from this alluvium, well yields range from 5 gpm to 120 gpm, with <br />average yields of approximately 17 gpm (page 38B of Section 2.04.7, Volume lA). <br />Steven's Gulch, an ephemeral stream, located to the west of the permit area, <br />drains an area of 6.0 square miles and contains several reaches of shallow <br />alluvium/colluvium. Most of these reaches have little ground water except <br />during periods of stream flow. The most significant area of <br />alluvium/colluvium occurs in the NW 1/4 of Section 13, T13S, R92W (Steven's <br />Gulch wellfield), where a 25 foot thick sandstone outcrop has created a <br />topographic restriction such that a considerable thickness of alluvial sands <br />and colluvial material have been deposited. Test wells drilled by the <br />applicant indicate that the alluvium in this area can support a pumping rate <br />of approximately 28 gpm (Ground Water Hydrology Appendix, Volume 4). The <br />applicant has installed a production well and currently uses this water for <br />domestic use, dust control, and fire control. <br />The recharge to the Steven's Gulch well field is through flow from the <br />adjacent colluvial deposits and from a leaky pipeline aqueduct. The ground <br />water flows through the colluvium downslope to the alluvium, where it becomes <br /> <br />