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• 9. 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 and the Colorado Division of Wildlife (DOW). For <br />cost estimating purposes, it is assumed that the Whirlwind portal will be backfilled; however, the <br />decision as to whether it will be backfilled or reclaimed with a bat gate will be made at the time of <br />closure in consultation with the BLM. A bat gate was also installed over the smaller portal at the <br />Packrat Mine while the larger portal was backfilled. Generally, a larger opening is preferred by the bats <br />and the reclamation cost estimate assumes that the larger portal will be reclaimed with a bat gate while <br />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. <br />The waste embankment final configuration will be created on an ongoing basis during mine operations; <br />therefore, less earthwork will be required at the end of the mine life to achieve the final contours. Map <br />C-3 shows that the grading at the end of the mine life is minimal. Final grading of the waste <br />embankment will include grading the remaining angle of repose slopes to 3H:1 V or less steep, placing <br />fill against the backfilled portal area to create slopes of 3H:1 V, and providing proper drainage for all <br />areas. It is expected that approximately 4,000 cubic yards of waste rock will be regraded with a Cat D- <br />7dozer. The final contours are shown on Map F and the cross sections are shown on Map C-3 (see <br />Appendix I). <br />No pocking of the surface at Whirlwind is specified since topsoil that is salvaged will provide a good <br />medium for plant growth and the recontoured slopes will not be as prone to erosion as the longer and <br />steeper slopes observed at the Packrat waste pile (see Packrat below). <br /> <br />Whirlwind Mine 07 (rev. April 08) E-9 <br />