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_ ,, <br /> <br />Letter to Robert Fleming 2 December 7. 1994 <br />5. In the application it is stated that except for installation of <br />the slurry wall, no excavation shall occur within 25 feet from <br />adjacent property lines. The Division needs some additional <br />detail regarding proposed slurry wall excavation and installation. <br />What is the proposed width of the slurry trench? How will the <br />slurry wall be keyed into bedrock? What is the nature of the <br />underlying bedrock? What is the composition of the slurry? Also, <br />please describe how the trench will be maintained during slurry <br />wall installation. Did Matrix engineers, inc. consider slurry <br />wall installation when they made the finding that surrounding <br />structures would be protected? <br />6. The application states that side slopes of the lake created will <br />be backfilled no steeper than a ratio of 2:1, except from 5 feet <br />above the expected water line to 10 feet below the expected water <br />line, where slopes shall not be steeper than 3:1. The Division <br />recommends maximum 3:1 slopes for all areas above the water line, <br />in order to facilitate revegetation. Also, since this site is <br />proposed for a post-mining use of Developed Water Resources, it is <br />possible that future use will result in a fluctuating water <br />surface elevation. The 3:1 side slopes should be constructed to <br />10 feet below the lowest anticipated water line during reservoir <br />use. Please provide the Division information on how the lowest <br />anticipated water line will be determined at the time of <br />reclamation. <br />7. Please commit following the reclamation recommendations in the <br />letter from Roy D. Bell included in Exhibits I and J, particularly <br />in terms of subsoiling, mulching, fertilization, weed control, and <br />grazing. <br />8. Please describe measures to be taken to ensure that backfilled <br />slopes will be stable and able to withstand erosive wave action at <br />the lake shoreline. How will backfill material be keyed into bank <br />(in situ) slopes? What measures will be taken to ensure adequate <br />compaction of backfilled slopes? Describe backfilling with sand <br />spoils in areas 1 and 2B in terms of attaining adequate compaction <br />to prevent future settling of the fill and to provide adequate <br />bearing capacity for proposed future urban development in area 2B. <br />9. In Exhibit D of the application it is stated that the South Platte <br />River channel improvements in Area 2C will be installed as soon as <br />the relevant approvals are obtained. If these improvements are to <br />be complete prior to the initiation of full scale gravel <br />extraction operations, bonding to cover the cost of the <br />improvements would not be necessary. However, if the river <br />channel improvements are to be completed later in the life of the <br />pit, bonding to cover these costs would be required and river <br />channel improvement details would have to be incorporated into the <br />reclamation plan. Please clarify this situation or provide <br />