2023-02-24_PERMIT FILE - M2022013 (4)

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Page 15 6.4.5 EXHIBIT E - Reclamation Plan free of groundwaters at the time of extraction. The balance of the basin floors (where needed) and slopes are also covered and compacted with the same materials until it meets the standards established under the August 1999 State Engineer Guidelines for Lining Criteria. Typical to obtaining approval for the constructed liner, the lined basin must pass a 90-day leak test. Correspondence from the OSE approving the construction of the lined basin will be submitted to the OMLR on receipt; or as part of any request for release of the permit, in part or whole. Essentially, the pushed parent rock material will form the minimum 3h:1y slopes of the basin and be compacted to a permeability of 10 forming a lined basin that complies with Colorado Water Law and Guidelines mentioned, above. In this manner, the lined basins will maintain a required separation and accounting of stored water from the underlying ground waters. Evidence of compliance with the rules and regulations of the Colorado Division of Water Resources will be provided to the OMLR on completion of the lined basins. Raptor has extensive experience successfully constructing lined storage reservoirs with several prior projects completed, tested and approved by the OSE. The deposit contains extensive materials suitable for use in constructing the liner including claystone, sandstone-claystone-siltstone and sandstone-siltstone bedrock, clay lenses in the sand and gravel deposit, and overburden often comprised of low plasticity sandy silty clay to silty sand. Excess topsoil has also been successfully used as a liner construction material and would be available from the temporary topsoil stockpile location in the North-East Section of Central Field. Other materials encountered within the sand and gravel deposit during excavation would be stored in temporary piles on the excavation floor. Parameters such as plasticity, percentage of fines etc. have not been determined for the deposit materials at this time but extensive experience in constructing several approved lined storage reservoirs with similar materials along the South Platte river provides high confidence in the availability of suitable materials within the extraction area. The liner will be progressively constructed once the pit is developed sufficiently to allow regrading and any problems with the efficacy of the liner can usually be detected prior to leak testing through evidence of seeps in the constructed liner which can have remedial action taken. Similarly, although not common, seeps are sometimes observed in the bedrock floor. While these have generally in Raptor's extensive experience proved to be self-healing, where needed remedial action and spot lining and compaction would be undertaken. Liner construction involves building a compacted low permeability core by placing and compacting suitable material in 6"± lifts. A Caterpillar 815 or 825 (or equivalent) compactor generally makes 2-4 passes to achieve suitable compaction of the core and which experience has shown provides integrity of the core both VARRA COMPANIES, INC. TWO RIVERS SAND GRAVEL AND RESERVOIR PROJECT MARCH 2O22 A REGULAR IMPACT[1121 CONSTRUCTION PERMIT APPLICATION-COLORADO DIVISION OF RECLAMATION MINING&SAFETY OFFICE OF MINED LAND RECLAMATION