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G-9 <br /> mineable limits as may be dictated by sand presence and/or quality characteristics). All mining <br /> will be carried out within the unconsolidated surficial(eolian) sand zone. <br /> As indicated in Item(1),above,there is the potential for mining activity to encounter localized and <br /> random saturated zones and/or perched groundwater(to the extent present);however,such features <br /> are classified as "aquicludes" (or"aquitards") and as such are not considered economic or yield- <br /> sustaining"aquifers". <br /> With respect to the regional and localized geology,CSC notes that the site is located in the Denver- <br /> Julesburg(D-J)Basin, a tectonic basin that is located in northeast Colorado, southeast Wyoming, <br /> and southwest Nebraska. The D-J Basin is bounded on the west by the Colorado Front Range <br /> (Dechesne,M. and others;2011). Areas of the D-J Basin that are adjacent to the Rocky Mountain <br /> Front Range have been divided into two sub-basins. The southern sub-basin is the Denver Basin <br /> and the northern sub-basin is the Cheyenne Basin. The Denver and Cheyenne Basins are defined <br /> by the extent of the Laramie Formation and are separated by a structural feature called the Greeley <br /> Arch(Kirkham and Ladwig; 1979). The Keenesburg No.2 Mine is situated on the northeast flank <br /> of the Denver Basin,with the sedimentary rock units dipping generally to the south and southwest <br /> at a gradient of 50 to 100 feet per mile. <br /> There are approximately 10,000 feet of Paleozoic to upper Cretaceous sedimentary rocks at the site. <br /> The more relevant geologic units at the site primarily consist of. (1) Pleistocene and Holocene <br /> unconsolidated eolian(windblown) deposits; (2) the Tertiary-Upper Cretaceous"D1" Sequence <br /> of the Denver Group; and, (3) the Upper Cretaceous Laramie Formation. Other relevant Upper <br /> Cretaceous units are the Fox Hills Sandstone and the Pierre Shale. These formations or units are <br /> described,in ascending order,as follows: <br /> The Pierre Shale (Upper Cretaceous), a marine deposit that overlies the Niobrara Formation, <br /> regionally may be up to 8,000 feet in thickness. However, beneath the Keenesburg No. 2 Mine <br /> project site, the Pierre Shale is about 6,000 feet thick (COGCC; 2019). The Pierre Shale is <br /> important because it is considered to be a low-permeability hydrogeologic confining layer that <br /> precludes significant downward movement of groundwater. The top of the Pierre Shale is about <br /> 600 feet below ground surface in the immediate area. <br /> Keenesburg No. 2 Mine_112 Reclamation Operation—November 22, 2019 <br />