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5)For the mine slope which is 100 feet away from the Middle Fork of the South Platte River,this <br /> slope can only be mined at a 2.OH:1 V angle. <br /> 6)Based on the site observations and discussing performance with the operators on site,Mr.Lewicki <br /> 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 signs <br /> of instability.No highwall should exceed MSHA requirements and any signs of instability must be <br /> addressed immediately through backfilling or other means. All newly constructed highwall mining <br /> slopes should not exceed 1.51-1:1 V.Depths above 60 feet vertically may require benching if any signs <br /> of instability are seen. The maximum depth of any excavation is 105 feet,keeping in mind that the <br /> track hoe reaches down approximately 16 feet from the final bench,thus the maximum height from <br /> the surface to the final equipment bench is only 89 feet. <br /> 7) The operation of the track hoe and trucks will provide minimal vibration to the slopes and will <br /> result in no effect on slope stability. This is based on years of experience of Greg Lewicki working <br /> in pits of various dimensions,slopes and with various equipment.No blasting will occur on this site <br /> and the material is so stiff in the bank that considerable breakout force is needed lust to excavate the <br /> material.The bank material absorbs the vibrations of the equipment with no resultant issues concerning <br /> slope stability. <br /> 8)Water infiltrating the gravel will not be an issue since the water table is approximately 60 feet below <br /> the surface in the majority of the 3 mine areas.In addition,all excavations below this level are dewatered <br /> by the mine pump,thus saturation of this material near the excavated slope is not possible.The fines <br /> in the material are also sufficient to resist loss of cohesion by the water,similar to a compacted embankment. <br /> An embankment compacted to 90%-95%maximum dry density is normally completely adequate to <br /> hold back water behind the embankment.Over millions of years,the weight of the material itself has <br /> caused similar natural compaction of the bank material and it is very strong. <br /> Gloria Z Mine 2013 Amendment 80 <br />