2008-07-11_PERMIT FILE - M2007044 (18)

Home Browse Search

Packrat The Packrat portal will require grading after the retaining wall is removed. The portal bench will be regraded to blend with the surrounding hillside except for a small flat area to be left at the base of the main portal. The final contours are shown on Map F and the cross sections are shown on Map C-5. The backfilling and grading will require dozing of approximately 3,200 cubic yards. The material will require a short uphill push with a D-7 dozer, at a grade of 33% and a length of approximately 240 feet. Pocking of the regraded surface will be required at the Packrat because the topsoil available for this site is poor (imported alluvium from lower elevation) and the slopes are relatively steep. Pocking consists of using the bucket of a hydraulic excavator to create a series of depressions in the slope surface where runoff can be retained so as to promote plant germination and reduce erosion. Pocking will be done on an area of approximately 0.99 acres using depressions of approximately 10 feet x 10 feet and 2 feet deep. If additional soil is available from stripping and reclamation at the Whirlwind waste embankment area, additional soil may be brought to the Packrat portal for reclamation. The • Whirlwind reclamation, however, will have no less than 12 inches of topsoil replacement. 10. Use MSHA Berm to Re-topsoil Packrat Portal Area All previous substitute topsoil used to reclaim the Packrat Portal area was stripped and placed along the perimeter of the Packrat Pad and Road to create the 3-foot high safety berm required by MSHA. During reclamation, this material will be removed and replaced on the pocked surface of the Packrat Portal area of approximately 0.99 acre. This material was previously calculated as having a volume of 672 cubic yards, assuming a soil depth of 5 inches. It will be placed carefully into the pockmarks. • Whirlwind Mine 07 (rev. April 08) E-10