2023-01-09_REVISION - M2021052 (23)

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Rifle Gravel Pit #1 January 20)3 stratum underlying the material to be mined is bedrock consisting of claystone and siltstone facies of the Wasatch Formation'. 5.2.1 Site Development and Grading (Phase 1) This section describes the mining methods, earthmoving, impoundments, and size of the areas to be worked during Phase 1. 5.2.1.1 Mining Methods and Earthmoving No mining will occur during Phase 1. This phase of the project will include minor site grading and vegetation removal on the Affected Lands, and construction of the Operations Pad and site access/driveway apron. Specific activities include the following: • Topsoil and overburden will be stripped; the overburden will be used to construct the required berms along the perimeter of the site, and the topsoil will be applied to the berms as a surface layer to support reclamation seeding. These berms will be placed at the inside edge of a 25-foot set back from the property line. These berms will be roughly 5-feet in height and 25-feet wide at the bottom and will also help control noise and visual impacts during operation (see Figure 11, Exhibit C6, specifically Berm Detail B/5). • A paved access apron will be constructed to access the project site from the CR 346, Interstate-70 frontage road. CDOT has reviewed the plans and issued an access permit to allow for this construction (See Attachment B). • A processing and sales facility (scale house) will be constructed at the entrance to the project site. This will include the material stockpile locations, loading chute and processor, the scale house, vehicle parking, and the minimal facilities needed for onsite staff(portable toilets, water tank, work trailer) (See Sheet 12 in Attachment A for a typical layout). • The topsoil and overburden (1-7 feet of fine sediments) will be removed from the mine area (see Figure 12, Exhibit D1 for a cross-section of the strata). The overburden will be used to construct a 5-ft tall perimeter berm around the mine area, to control visual and noise impacts in accordance with Garfield County Land Use Code (LUC) standards. The berm will be surfaced with the salvaged topsoil. The outer edge of the perimeter berm will be located 25 feet from the boundary of any wetland areas, in accordance with LUC standards pending approval of a variance from the 35-foot setback in the LUC. The berm surface will be stabilized and re- seeded to control erosion. Remaining topsoil and overburden material will be stockpiled at the processing facility for sale, as described below in Section 5.2.1.2. Note that the thickness of topsoil and overburden across the site vary. The boring holes indicate the overburden thickness can vary from 1 to 7 feet. Attachment C includes the typical cross-sections at the boring holes. ' United States Geological Survey.Geology map of the Silt quadrangle,Garfield County,Colorado.Miscellaneous Field Studies Map MF-2331.Reston,Va:U.S.Department of the Interior.2001 25