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Rifle Gravel Pit#1 May 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 application of the perimeter berm. The access road and driveway improvements will <br /> also be constructed during this phase. 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 the <br /> mine area, to control visual and noise impacts in accordance with Garfield County Land <br /> Use Code (LUC)standards, comply with the Garfield County Permit conditions, and the <br /> United States Fish and Wildlife Services' recommendations. The berm surface will be <br /> surfaced with topsoil and stabilized immediately after construction, and re-seeded as <br /> soon thereafter as practical based on seasonal conditions. The excess overburden and <br /> topsoil material will be stockpiled on-site and be sold as a secondary commodity, with <br /> the exception of 566 CY of topsoil to be stored and used for final reclamation. <br /> Attachment C includes the typical cross-sections at the boring holes. The estimated <br /> areas and volumes of material excavated and used for the berm construction and <br /> revegetation during Phase 1 (P1) are provided in Table 2 and summarized below: <br /> • Total overburden removal quantities (estimate): <br /> o 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 <br /> • Excess overburden for sale post-berm construction (secondary commodity) (estimate): <br /> o 30,423 CY <br /> • Excess topsoil for sale post-berm construction (estimate) <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 />