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concluded that highwalls could be included in the mining operation as long as site personnel were <br />observant for any cracks, mud zones, gravel zones without cementing fines, slips, or any other <br />signs of instability. No highwall should exceed MSHA requirements and any signs of instability <br />must be addressed immediately through backfilling or other means. Highwall slopes should not <br />exceed 80 degrees from horizontal. Depths above 60 feet vertically may require benching. <br />It appears that there is a zone of some gold in the gravel from the surface to a depth of <br />approximately 20 -30 feet, followed by a barren gravel zone of 30 -40 feet followed by a zone of up <br />to 25 feet that contains a higher percentage of gold. The barren zone will be used to backfill <br />previous pits and the other material will be sent to the plant for processing. Some of the washed <br />gravel will also be used for backfilling and other material may be further crushed and screened for <br />gravel product sale. <br />Once the initial pits have been excavated, barren material and washed gravel will be used to <br />backfill previous pits. The maximum amount of pit that requires backfilling will be limited to <br />20,000 cubic yards. <br />A current highwall of approximately 60 feet height will be implemented at the south end of the <br />infiltration pond. This pond will later become the settling pond for the processing plant and the <br />highwall will eventually be filled in from the ongoing processing. It is, however, understood that <br />the highwall must be bonded for the worst case, which is the current condition. <br />This current highwall at the infiltration pond will require 12,000 cubic yards to backfill to the <br />accepted post -mine land use of rangeland. A swale will be left in the landscape but no slope will <br />be steeper than 4H:1 V. <br />