2024-01-31_REVISION - M1977344 (18)

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Portland Limestone Quarries (M-1977-344) Permit Amendment-02 Holcim US Inc, 3500 Highway 120, Florence, CO 81226 Revised pursuant to preliminary adequacy review November 20, 2023 Phone (719) 288-1443 www.holcim.us 70 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, foraminiferal 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, argillaceous limestone that previously was used for high-lime at the old Portland plant. Except for a 7 to 12-feet-thick basal layer that transitions into the Fort Hays Limestone in which the lime content is nearly of cement quality, and the buff argillaceous limestone cap, the Smoky Hill Limestone is considered overburden. Numerous northwest-trending fold and fault structures 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 structural 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. 2.4.3 Mine Progression Mining will commence in the northwest corner of the resource area and progress south and east through the resource over the course of approximately 100 years. The mine plan is set up in 10-year blocks based on plant capacity (Figure 2.4.3-1). During Years 0 to 10, mining will be initiated in the west side of the property with extraction progressing north in Section 24 and south into Section 25 in Fremont County simultaneously. Anticipated acres affected each 10-year period is provided in Table 2.4.3-1. Table 2.4.3-1 Acres Affected Per 10 Years CUT NO. AREA (ACRES) Development 18 0 to 10 years 216 10 to 20 years 269 20 to 30 years 240 30 to 40 years 478 40 to 50 years 679 50 to 60 years 276 60 to 70 years 334 70 to 80 years 273 80 to 90 years 101 90 to 100 years 191 TOTAL 3,074