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Total: 5,516 cy <br /> <br />The material will be obtained by regrading the treatment pad area and from the adjacent fill stockpile <br />shown on Map C-2. Using a D-7 dozer, a unit cost of $0.50 per cubic yard and a total cost of $2,758 <br />are estimated. <br />The Whirlwind Sediment Pond will not be backfilled until the vegetation is adequate to control erosion <br />from the site. At that time, the ditches that drain to the Sediment Pond will be allowed to drain to the <br />ephemeral branch of Lumsden Creek. See Map F in Appendix I. These ditches aze designed for the 100 <br />year 24 hour event and they aze meant to carry runoff off the site in a controlled manner. Any <br />associated culverts under the county road will remain. The culvert within the waste rock area will be <br />removed and replaced with aloes-water crossing that will allow future access for reclamation <br />monitoring and maintenance. This minor earthwork will be done with a D-7 dozer or smaller, at a cost <br />of $1,000. Therefore, the total cost for pond and ditch removal is $3,758. <br />• 10. Backfilling and Grading at Portal Areas <br />Whirlwind <br />The Whirlwind decline was originally equipped with a bat gate; however, no bats were found in the <br />mine during inspections conducted by the BLM. For cost estimating purposes, it is assumed that the <br />Whirlwind portal will be backfilled; however, the decision as to whether it will be backfilled or <br />reclaimed with a bat gate will be made at the time of closure in consultation with the BLM. A bat gate <br />was also installed over the smaller portal at the Packrat Mine while the lazger portal was backfilled. <br />Generally, a lazger opening is preferred by the bats and the reclamation cost estimate assumes that the <br />larger portal will be reclaimed with a bat gate while the smaller portal will be backfilled. <br />Backfilling of the Whirlwind portal will consist of pushing material from the portal pad into the mine <br />opening for a distance of 20 feet. Then additional material from the pad will be backfilled to a height <br />• of 10 feet above the top of the portal opening to the existing bench at a slope of 3H:1 V. This backfill <br />volume is 820 cubic yards. The cost of this backfilling and grading is $1.20 per cy, therefore the <br />estimated cost for this work is $984. <br />Whirlwind Mine June 07 E-10 <br />