2012-10-29_PERMIT FILE - M2012045 (6)

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These are construction of the slurry walls, construction of the earthen embankment dams and construction of the zoned perimeter dam. There may be some backfilling the pit cells with excess overburden as necessary to ensure protection of the slurry wall backfill. However, it is intended that the site will be mined at a slope angle protective of the integrity of the virgin material inboard of the slurry wall once the excavation is close to the toe of the final pit slope. (The construction site for the zoned perimeter dam will be excavated to bedrock so that the key trench may be cut, the clay core, perimeter drains, and backfilled and compacted fill slopes constructed. Therefore, adjacent pit slopes during construction will likely be steeper than 3h: 1v.) If backfi l is found necessary, it will be done in six inch (6 ") to twelve -inch lifts, commensurate with the quality of the replaced material and structures design specification. The pit floor will be left as is, once the sand and gravel are removed. (No waste asphalt or cement will be place in any portion of the excavated cells intended as developed water resource. However, if it is necessary to dispose of such material on- site, it will be placed in dry areas of the Operation according to applicable local, state and federal regulations.) Typical equipment, such as front -end loaders, dozers, scrapers or any combination, will be used to move earthen materials on -site. Slurry walls are an integral part of the proposed reclamation plan. Following is a conceptual plan for slurry wall construction and a typical Quality Assurance and Quality Control (QA /QC) program. A set of detailed plans and a detailed QA /QC program will be provided once other key permits and approvals are obtained by the Applicant /Operator. No slurry wall construction will begin until a detailed slurry wall construction plan and detailed QA /QC program are received and approved by the Division. (Appendix IV is a Design Report prepared for the SEO for Phase One Reservoir.) The detailed designs for the earthen embankment dams and zoned perimeter dam have been submitted to the Office of the State Engineer for review and approval. The Division of Water Resources has accepted the Design and Construction Documents for the Central Reservoir please see the letter dated March 14, 2008 from the Division of Water Resources located in EXHIBIT "G" WATER INFORMATION. Conceptual Slurry Wall Construction Plan The following Conceptual Slurry Wall Construction Plan is based on a paper by C.R. Ryan and S.R. Day, Titled "Soil - Bentonite Slurry Wall Specification ", Geo- Solutions Inc., Pan American Conference on Soil Mechanics and Geotechnical Engineering, Geo- Institute and MIT, Cambridge, MA, June 2003. 1. Slurry Parameters Slurry Test Methods; The following field- testing methods will be performed according to ASTM specifications and at a frequency as recommended in the Divisions guide titled "Guide to Specification Preparation for Slurry Walls and Clay Liners as a Component of a Colorado Mined Land Reclamation Permit ": • Viscosity -Marsh Funnel • Unit Weight -Mud Balance • Filter Press • Sand Content Slurry Properties When Freshly Mixed: • The Viscosity -Marsh Funnel test will be performed to determine the