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Bureau of Land Management Environmental Assessment <br /> Royal Gorge Field Office DOI-BLM-CO-F020-2020-0036 EA <br /> Mining and Processing <br /> Mining is proposed to progressively trend toward the north/northwest with final highwall/bench <br /> dimensions being a sequence of 10-foot-wide by 40-foot-high benches with a maximum 120-foot <br /> highwall. The interstitial sequences would contain 1:1 slopes with an overall highwall slope of <br /> 1.25:1.0(Figure 3). No rock berms are proposed along the benches; however, earthen berms <br /> located along the top of the highwall would be utilized for stormwater control to divert surface <br /> water towards the outer portions of the bench system to the main stormwater drainage channels. <br /> Monitoring and maintenance would occur to ensure bench stability(e.g.,raveling, tension <br /> cracks, rock falls etc.). All safety regulations and precautions (e.g., following all federal, state <br /> and county permit/contract stipulations and monitoring, daily visual inspections, signage, site <br /> specific training, etc.)would be taken during scheduled maintenance. As part of the mineral <br /> material contract stipulations, a geotechnical stability analysis would be conducted, by a <br /> Professional Engineer(PE)to assess the overall stability of the proposed final highwall/bench <br /> configuration, if at any point instability would become a consistent issue. <br /> Once the proposed mining area has been leveled and benched, mining would commence by <br /> blasting the material top down. Colorado Quarries schedules blasting on an as needed basis, as <br /> mining progress north. Drilling would occur to a depth of 20 feet with an average+/-40 holes <br /> per blast(reference the general blasting pattern in Appendix A). The blasting materials consist of <br /> primers, ammonium nitrate/fuel oil (anfo),detonating cord and surface delays with 60 pounds <br /> per delay of maximum explosives. Noise levels would be reduced since mining is planned to <br /> occur below surface level. The ridge along the south side of the quarry also provides a noise and <br /> visual buffer for blasting and overall daily operations. To date,there have been no complaints or <br /> concerns regarding blasting controls at the site. All MSHA regulations would be enforced <br /> including a licensed blaster onsite to plan, load and monitor each shot. The most recent blasting <br /> plan would continue to be applied to all proposed future blasting. Explosive materials would be <br /> stored on private lands in a Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) <br /> authorized storage container. All federal laws and regulations pertaining to the storage and <br /> handling of explosives would be followed accordingly. <br /> Following a blast, the material would be pushed over the highwall face with a bulldozer or <br /> carried over the edge using a front-end loader. The loader would then haul the freshly blasted <br /> material to a crusher/screener conveyor system. The material is "primary crushed"and screened <br /> to a 1-'/2 inch. Any oversized material is then"secondary crushed"down to '/4 inch minus. Final <br /> products would be '/4 inch minus and 1 '/2 inch minus and sold as fill and landscaping materials. <br /> All material would be considered product with zero percent process waste with no rejects. Final <br /> products would be stockpiled for short timeframes,until it could be hauled offsite and scaled. No <br /> water would be used during processing. Depending on material demand and future northern <br /> reserves,the operator proposes to install a scale house and scale to weigh all product prior to <br /> hauling. Below Table 1 lists the types of equipment and their subsequent use(s) onsite: <br /> 9 <br />