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• Chtl-RB -Exhibit ~ <br />Water Iafotmatioa <br />Page 7 <br />floodplain deports are considered by the CGS to be the principal water table aquifers in the Boulder - <br />Greeley -Fort Collins area and have well yields of medium 1p large in the plains (15 gpm to greater <br />than 100 gpm) and small to medium pens than 100 gpm) in the mountains. <br />Pierre Shale -The Pierre Shale of Cretaoeotrs age outcrops or subcrops in the southern half of the <br />Dowe Flats project area. Regionally, it is approximately 8,000 feet thick and is comprised of dark gray <br />to black marine shale with some sandstone beds, the most prominent being the Hygiene Sandstone <br />Member located about 1500 feet above the base of the formation. The formation yields very small <br />amounts of water of poor quality to wells from weathered zones and the Hygiene Sandstone. The <br />yields are reported by the CGS as being inadequate pass than one gallon per minute). <br />Nobrara Formation - The Niobrara Formation of Crelaoeoru age lies below the Pierre Shale and <br />subcrops along the north, east and western flanks of the Rowe Flats syncline. The formation is <br />composed of calcarears marine shale and limestone that yields very small quantities of water to wells. <br />This formation is reported by the CGS to have inadequate well yields pass than 1 gpm). Figure Gfi <br />• is a geologic section showing the average thickness of the minable units within the Niobrara <br />Formation. <br />Benton Formation -Also called the Benton Shale; this formation of Cretaoeorrs age mnrsLs of marine <br />shale, limestone, siltstone and a thin sandstone unit (the Codell Sandstone) rrear the top. It is reported <br />to have inadequate well yields similar to the Nobrara Formation. 'This formation outcrops outside the <br />eastern and western margins of the proposed mine area. <br />Dakota Grow -Also known as the Dakota Sandstote; these are five members in this group oonrsting <br />of sandstone, shale, conglomerate and silty rarbonaceorrs shale. The Dakota yields small to moderate <br />pass than 100 gpm) quantities of water to wells near the outcrop. This is the resistant rock which caps <br />the hogback ridges along the western flank of the Dowe Flats valley and Rabbit Mountain along the <br />eastart flank. <br />The wconsolidated valley fill material is the principal aquifer at Dowe Flats. Four monitoring wells <br />were installed in these deposits to evaluate the local hydrology. The wells were completed in the valley <br />fill material and the weathered bedrock zone just below it. Well completion details are included in <br />"Report on Groundwater Monitor Well Inshallation, Dowe FL3ts Project" by Western Technologies Inc. <br />• <br />