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Above the Upper Sandstone is the Placita bed <br /> • coal seam, approximately 3 ' -7 ' thick, forms the base of the <br /> Paonia Shale Member . <br /> The Paonia Shale Member includes shales , <br /> siltstones , sandstones and occasional thin coal , including <br /> the Sunshine seam, which is 18"-4 ' thick, and occurs 50 ' -60 ' <br /> above the Placita seam. <br /> The upper boundary of the Paonia Shale is <br /> indistinct . It merges into the upper , undifferentiated <br /> Williams Fork, which outcrops as the resistant upper rim <br /> surrounding the Coal Basin . <br /> b . Groundwater <br /> Zones which might potentially be water <br /> saturated in the Coal Basin mine plan area are the Rollins <br /> • Sandstone member , the Middle Sandstone member , and the Upper <br /> Sandstone member . <br /> The Rollins is approximately 140 ' thick, <br /> the Middle is approximately 120 ' thick, and the Upper is <br /> approximately 50 ' thick. As the west side of Huntsman Ridge <br /> is controlled by the geologic structure of the dipping <br /> Mesaverde formation, the three sandstone units remain at <br /> approximately the same depth below the ground surface throughout <br /> the mine plan area . <br /> Recharge to the Mesaverde occurs principally <br /> through th.e outcrop area on the east and west sides of <br /> Huntsman Ridge. Water which enters the outcrop migrates <br /> 31 . <br />