2015-02-24_REVISION - M1974086 (9)

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d) Specify if a Geotechnical Evaluation has been performed for the proposed area of fill placement. The Geotechnical Report should include, at a minimum, information about the design and placement of fill material, compaction standards of fill material, optimum moisture conditioning, lift thickness, testing frequency for compaction and moisture conditioning. A Geotechnical Evaluation of the backfill slope has been conducted by Greg Lewicki and Associates. Using an analysis of the material by the Colo. Dept. of Transportation, GLA has determined the backfill slope in questions to have a safety factor of 1.8. See the revised Geotechnical Stability Exhibit for details. e) Specify the type of equipment used to place and compact the fill material. The backfill will be placed with haul trucks and other earth- moving equipment. f) Specify where the fill material will come from, e.g. cut and fill or stockpiles. All backfill material will come from screened topsoil. This topsoil material will be available from both stockpiles and recent activity. 20. The Reclamation Plan calls for creating vegetation islands on the western quarry wall. The Applicant has stated that 10,000 cubic yards of material would be used to create the vegetation islands. Please specify the average volume of a single vegetation island. In addition, please specify if the vegetation islands will be placed along the entire vertical length (from anticipated water level to top of quarry wall) of the western wall. 30 to 50 vegetation islands will be built, with the amount of material per island depending on the islands location. The islands will be placed anywhere along the western slope from the top down to the estimated top of reservoir water level. 21. The map labeled `C -4: Cross Sections' states compost may be added to the vegetation islands. Please specify the type of compost to be used. This information is necessary to accurately estimate the cost associated with creating the vegetation islands. The Division recommends performing a soil test on the soil medium to be used for the vegetation islands in order to determine the appropriate type and rate of compost. Map C -4 has been revised to remove the reference to compost. All vegetation islands will be constructed using the screened topsoil material. 22. The Applicant is proposing to reclaim the quarry to a water storage reservoir. The Amendment Application does not address the suitability of the reclaimed site to function as a reservoir. Page G -2 of the Amendment Application states the detail on the hydrologic conditions in Ralston Quarry is provided in Appendix 2. The Brierley Report contained in Appendix 2 addresses the slope stability for the proposed final configuration of the quarry, 7