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<br />Groundwater Hydrology <br />i <br />Rocks exposed in the mine area are a 250' stratigraphic interval <br />of the Iles Formation (See stratigraphic Chart in the Geology report) <br />which enclose the No. 2 coals of the Lower Coal Group. The base of this <br />interval is about 50 feet below the Blacksmith coal seam and the top is <br />about 50 feet above the upper Pinnacle rider. This interval of rocks <br />consists of beds of shale, coal, sandy shale and thin sandstones formed <br />into a topographic high. These beds dip to the west and plunge to the <br />north. The shales and sandy shales are virtually impervious and the sandy <br />units are tight and thin, lensy and discontinuous. <br />Appreciable water (5 gpm or more) was encountered only near the tops <br />of holes drilled in valley bottoms. This is interpreted as near-surface <br />water in alluvium. <br />• A water supply well was drilled in 1979 (79-4B) in an attempt to <br />provide water for dust control. This well has been a disappointnent in <br />terms of gpm of production. Static water level is about 55 feet and flow <br />is estimated at less than 30 gpm under sustained pumping. This well (See <br />location of Hole 79-4B on the Geology Map) was collared a few feet below <br />the Pinnacle coal seam outcrop and penetrated 599 feet of rocks and bottomed <br />neaz the top of the Tow Creek Sandstone. Water is appazently coming from <br />two low permeability sandy shales (Kil rocks) at 70 feet and 120 feet and <br />three tight sandstones at 300 feet, 450 feet, and 550 feet. Beds here aze <br />dipping 10 to 14o to the west. We have no data on the water quality of <br />this well; it is used to maintain water level in a stock pond (used as a <br />surge tank for road watering water supply). Due to the lack of appreciable <br />ground water in the mine area, in beds associated with coal and with mining <br />activities, no groundwater monitoring program is contemplated. Ground water <br />is present in alluvial material in the valley of Grassy Creek and because <br />of its relationship to ,surf ace flow has been addressed under Surface water <br />Hydrology. <br />•\ <br />II.E-2 <br />