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2. Geology and Hydrogeology 2.1 Site Geology The following description of Site geology was developed from information gathered during previous Site investigations (RGI, 1999; Holnam, 1977, and Fremont Sanitation District, 1994, as cited in RGI, 1999). The Site is located in the Canon City embayment created during a period of crustal deformation in late Cretaceous and early Cenozoic time. Cretaceous marine sediments of the Florence-Canon Ciry area were deposited in the sedimentary embayment that is now a stmctural basin with steeply dipping east and west limbs and associated smaller fold structures. Exposed strata at the Site include the Fort Hays Limestone and the more azgillaceous Smoky Hill Limestone, both members of the Niobrara Formation. Beneath the limestone lies the Codell Sandstone Member of the Carlile Formation followed by the Blue Hill Shale Member of the Carlile Formation (Figure 3). The Codell Sandstone of the Carlile Formation consists of approximately 13 to 25 feet of a light grey, fine- grained, massive, slightly calcareous sandstone. Contact with the overlying Fort Hays Limestone is marked by a 2- to 3- foot thick transitional zone of dense, arenaceous limestone. The Fort Hays Limestone of the Niobrara Formation conformably overlies the Codell Sandstone and consists of approximately 35 feet of medium to light gray, distinctly bedded limestone that contains numerous thin seams of dark grey, calcareous, fotaminiferal clay. This limestone is quarried for use in cement production due to its high lime content. Minor amounts of pyrite, both as nodules and as finely disseminated crystals, are present throughout the member. Fossils of Inoceramus deformus are found occasionally in the broken quarried rock The Smoky Hill Limestone of the Niobrara Formation conformably overlies the Fort Hays Limestone and consists of up to 124 feet of dark grey, thin-bedded, highly fissile, soft, calcareous shale that contains numerous 1- to 3-feet thick, light grey limestone beds, and is capped by a buff to yellowish tan, more thickly bedded, azgillaceous limestone that previously was used for high-lime at the old Portland plant. Except for aseven- to twelve-feet thick basal layer that transitions into the Fort Hays Limestone in which the lime content is nearly of cement quality, and the buff azgillaceous limestone cap, the Smoky Hill Limestone is considered overburden. Numerous northwest-trending fold and fault stmctures are found in and around the Site. The Site is situated on the nearly horizontal east limb beds of a small anticline, the Brush Hollow Anticline, which lies just east of the major Florence-Canon City structwal basin (i.e., syncline). The exposed strata in the quarry appear to be dipping slightly to the southwest at an angle of approximately 4 degrees. Structural deformation can be seen throughout the quarry area, occurring as minor reverse faults and graben structures in the limestone beds. Several of these faults have been observed along the west and north walls of Cut 7 and through the northwest comer of Cut 10. Movement along these faults ranges from a few feet to a few tens of feet. In addition, a major fault zone parallels Bear Creek east of the current quarry area. This zone occws as a series of normal faults with up to 120 feet of displacement. 2.2 Site Hydrogeology The following description of Site hydrogeology was developed from information provided in (RGI, 1999; K-S & Company, 2001). Groundwater recharge in the region occws from infiltration of precipitation, return flow BLASLAND, BOUCK & LEE, INC. tsn3roz engineers 8 scienfis is 2-1 GrouMwattr Manibring PUn n dor