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r <br />• • <br />stockpiled in the buffer zones prior to initiation of concurrent reclamation. The designated <br />buffer zones are not adequately sized to hold this amount of topsoil in a stable configuration. <br />Please clarify this apparent discrepancy. <br />4. Response acceptable. <br />5. Original comment - /t is assumed that the interior pit slopes wi// be vertica! mining faces with a <br />maximum length of 1150 feet. Costs for cur and fill reduction of these faces, to a 3: 1 slope, <br />will be included in the Division's reclamation cost estimate. if these assumptions are <br />incorrect, please specify the maximum length and grade of interior highwall that will exist at <br />any time during the operation. <br />Some clarification is required here. The Division's reference to interior pit slopes is regarding <br />slopes that are temporary during the mining operation, not the final pit perimeter slopes. It is <br />assumed that these slopes will remain vertical since they will be removed during subsequent <br />excavation. While mining the southeast quadrant of the site these slopes would be the north <br />and west sides of the excavation; while mining the southwest quadrant this slope would be <br />the north side of the southeast and southwest quadrants; while mining the northwest quadrant <br />these slopes would be the east side of the northwest quadrant and the north side of the <br />southeast quadrant. The length of these interior slopes (highwall) is estimated at an average <br />1,150 ft and is the dimension used in the cut and fill slope reduction included in the Division's <br />reclamation cost estimate. This highwall length figure would be reduced by one half if the <br />south side of the initial processing area is to be mined at a 3:1 slope for stability of this <br />processing area slope during the life of the pit. Please indicate the proposed maximum length <br />of vertical highwall that will exist during mining operations at this site. <br />6 - 1 1 . Response acceptable. <br />The figures submitted in the preliminary reclamation cost estimate still appear to be accurate for <br />reclamation of this site under a permit revocation/bond forfeiture scenario. If no changes are <br />warranted by your response to this review, the amount shown on the calculation summary form is <br />the amount of financial warranty that will be required before the Villa Grove Pit permit will be <br />issued. <br />If you need additional information, please contact me at the Division of Minerals and Geology, <br />Durango Field Office, 701 Camino Del Rio, Room 125, Durango, Colorado 81301, telephone no. <br />970-247-5062. <br />Sincerely, <br />~~ <br />Steve S. Shuey <br />Environmental Protection Specialist <br />Enclosure <br />