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Rifle Gravel Pit#1 June 2023 <br /> The stratum underlying the material to be mined is bedrock consisting of claystone and <br /> siltstone facies of the Wasatch Formation'. Gravel and sand will be the primary commodities <br /> that will be mined/extracted. These materials will support various construction projects in the <br /> region and will be available for sale. The excess overburden and topsoil will be sold as <br /> secondary commodities (with sufficient topsoil reserved in a stabilized stockpile for final <br /> reclamation purposes). See Figure 12, Exhibit D1 for a cross-section of the strata. <br /> 5.2.1 Site Development and Grading (Phase 1 [P1]) <br /> This section describes the earthmoving, impoundments, and size of the areas to be worked <br /> during Phase 1. <br /> 5.2.1.1 Mining Methods and Earthmoving <br /> No mining will occur during Phase 1. This phase of the project will include minor site grading <br /> and vegetation removal within the Permit Area on the Affected Lands and construction and <br /> topsoil and seeding application of the perimeter berm. The access road and driveway <br /> improvements will also be constructed during this phase, upon issuance of the new CDOT <br /> Access Permit. Specific activities include the following: <br /> • The topsoil and overburden (vary across the site, 1 - 7 feet of fine sediments)will be <br /> removed from the Affected Area (Figure 12, Exhibit D1 for a cross-section of the <br /> strata). The overburden will be used to construct a 5-foot-tall perimeter berm around <br /> the mine area, to control visual and noise impacts in accordance with Garfield <br /> County Land Use Code (LUC) standards, comply with the Garfield County Permit <br /> conditions, and the United States Fish and Wildlife Services' recommendations. The <br /> berm surface will be decompacted, surfaced with topsoil and temporary seed mix as <br /> soon thereafter as practical based on seasonal conditions. The excess overburden <br /> and topsoil material will be stockpiled on-site and be sold as a secondary commodity, <br /> with the exception of 566 CY of topsoil which will be stored and used for final <br /> reclamation of the greenbelt during Phase 3. Attachment C includes the typical <br /> cross-sections at the boring holes. The estimated areas and volumes of material <br /> excavated and used for the berm construction and revegetation during Phase 1 (P1) <br /> are provided in Table 2 and summarized below: <br /> • The average centroid to centroid haul and grading push distances for overburden <br /> and topsoil placement to construct the berms is 250 feet- 350 feet. <br /> • Total overburden removal quantities (estimate): <br /> 0 11.18 acres [54,111 cubic yards (CY)] <br /> ■ 30" cut = 42,267 CY <br /> ■ 6" topsoil = 11,844 CY <br /> • Berm quantities (estimate): <br /> 0 2.87 acres (11,528 CY overburden) <br /> 0 2,305 CY topsoil for reclamation <br /> United States Geological Survey.Geology map of the Silt quadrangle,Garfield County,Colorado. Miscellaneous Field <br /> Studies Map MF-2331. Reston, Va: U.S. Department of the Interior.2001 <br /> 22 <br />