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• 18. Backfill Sediment Pond and Collection Ditches <br />The sediment pond must be backfilled. The estimated fill volume is 4,608 cubic yards (cy).The <br />material will be obtained by regrading the treatment pad area and from the adjacent fill stockpile <br />shown on Map C-2. <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 are designed for the <br />100-year, 24-hour event and they are 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. <br />19. Post-Reclamation Site Drainage <br />~~ <br />~J <br />The entire Packrat permit area will drain to the ephemeral drainage to the east, as in the past prior to <br />mining. The reclamation of the Packrat Road will restore the natural drainage to a configuration that <br />more closely approximates pre-mining conditions than that which currently exists. The Whirlwind area <br />will be altered slightly since the permanent diversions around the reclaimed waste rock pile will <br />remain to keep as much water off the waste as possible. The final layout of these permanent ditches is <br />shown on Map F. <br />20. Weed Control <br />Appropriate measures will be employed to minimize the occurrence and spread of noxious weed <br />species. The Weed Control Plan for the site will include: <br />1) A weed survey will be made of the permit area each spring in April or May. <br />• <br />Whirlwind Mine 07 (rev. April 08) E-16 <br />