Laserfiche WebLink
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, or equivalent, at a cost of $0.75 per cubic yazd. Therefore a total cost of $3,000 is estimated. <br />The final contours aze shown on Map F and the cross sections are shown on Map C-3 (see 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 />Therefore, the estimated subtotal for backfilling and grading at Whirlwind is $984 + $3,000 = $3,984. <br />• Packrat <br />The Packrat portal will require grading after the retaining wall is removed. The portal bench will be <br />regraded to blend with the surrounding hillside except for a small flat azea to be left at the base of the <br />main portal. The final contours aze shown on Map F and the cross sections aze shown on Map C-5. The <br />backfilling and grading will require dozing of approximately 3,200 cubic yazds. The material will <br />require a short uphill push with a D-7 dozer, at a grade of 33% and a length of approximately 240 feet. <br />This represents a unit cost of about $1.00 per cubic yard; therefore, a total cost of s $3,200 is <br />estimated. <br />Pocking of the regraded surface will be required at the Packrat because the topsoil available for this <br />site is poor (imported alluvium from lower elevation) and the slopes aze relatively steep. Pocking <br />consists of using the bucket of a hydraulic excavator to create a series of depressions in the slope <br />surface where runoff can be retained so as to promote plant germination and reduce erosion. Pocking <br />of the azea of approximately 0.99 acres using depressions of approximately 10 feet x 10 feet and 2 feet <br />deep will cost approximately $2,800. If additional soil is available from stripping and reclamation at <br />the Whirlwind waste embankment azea, additional soil may be brought to the Packrat portal for <br />Whirlwind Mine June 07 E-11 <br />