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Wattenberg Lakes Amendment, Exhibit D—Mining Plan May 2023 <br /> 2.0 PHASING AND METHODS OF MINING <br /> 2.1 Phasing <br /> Holcim anticipates conducting operations under this DRMS permit amendment in three phases for a total duration <br /> of 18 months, with mining of Area 1 and Area 2 planned for only 2 months of that duration and the other activities <br /> as part of reclamation (discussed in Exhibit E). The three phases are: <br /> 1. Phase 1 —Concurrent activities (10 months) <br /> a. Grade/fill to achieve side slopes of 3HA V (horizontal:vertical) <br /> b. Build up south edge of existing Pond 1 on south side to create 40-ft buffer from top of pond slope <br /> to county road <br /> c. Mine areas 1 and 2 <br /> d. Place fill in other parts of the site to achieve reclamation grades <br /> 2. Phase 2—Construct slurry wall and perimeter drain (2 months) <br /> 3. Phase 3—General earthwork on western side of footprint (excess fill to be used for backfill as needed in <br /> other parts of the site) (6 months) <br /> In Phase 1, prior to or while initiating mining in Area 1 and Area 2, the Pond 1 side slopes will be graded to the <br /> base of the pond at a 3H:1 V slope. Also, excess fill from the western portion of the Pond 1 footprint area will be <br /> used to build up the southern perimeter of Pond 1 to create a 40-ft offset from the county road to the top of the <br /> pond embankment. Area 1 and Area 2 will be mined and excess fill (placed previously in the western part of the <br /> footprint) removed and placed in the cottonwood replacement area or other areas where fill is required to achieve <br /> the reclamation grades. Also, in areas outside Area 1 and Area 2, minor earthmoving and grading will take place <br /> to establish reclamation grades for wetland establishment, cottonwood replacement, and other reclaimed uses as <br /> presented in Exhibits E and F. <br /> In Phase 2, the slurry wall and perimeter drain will be constructed around the perimeter of the final footprint of <br /> Pond 1. Design specifications for the slurry walls and quality control procedures used during construction will <br /> ensure that the reservoirs meet State Engineer's Office (SEO) performance standards. Specific specifications and <br /> quality control procedures will be provided to the Division for review prior to construction of the slurry walls. <br /> After construction of these reclamation features, Phase 3 general earthwork will take place on the western side of <br /> the Pond 1 area and excess fill not used in this area will be used to achieve reclamation grades in other parts of <br /> the site. <br /> 2.2 Equipment <br /> The aggregate material will be recovered using equipment and facilities typical for sand and gravel mining <br /> operations. The equipment and facilities may include, but not be limited to, a conveyor system from the mining <br /> area to the Holcim's Platte Valley Plant; additional, portable, temporary processing equipment on an as needed <br /> basis for screening, crushing, and washing; earth-moving equipment including dozers, loaders, scrapers, <br /> excavators, dragline, dredge, compactors, and field conveyors; and an employee/storage trailer and <br /> fueling/lubricating station. Dewatering pumps and generators and watering trucks will be also used as needed. <br /> 2.3 Mining Process <br /> The typical mining process for Area 1 and Area 2 will involve stripping growth medium and overburden with <br /> scrapers, to expose the aggregate product below, and stockpiling these materials in the temporary stockpile areas <br /> identified in Exhibit C. Mining of the aggregate will progress down to the underlying claystone bedrock. The <br /> bedrock material is rippable and, when necessary, will be excavated and used for reclamation. <br /> Overburden found on the site will be used to fill in the reclamation slopes and for minor grading and fill needed in <br /> other areas as part of reclamation. Overburden and growth medium reserved for reclamation will be vegetated <br /> and stabilized in accordance with Rule 3.1.9(1). All soil and overburden material will be used for reclamation, so <br /> long-term stockpiling of these materials is not anticipated. The mining areas will be reclaimed using soil, <br /> OTETRA TECH Page 214 <br />