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II) Underground Mine Workings <br />A) Discovery <br />During cut to fill near UG #4049 timber and narrow gauge rail was encountered. The "bridge" was <br />given a project designation of UG #4067. <br />B) Drilling <br />Confirmatory drilling was performed at Underground Working #4007. A drill pattern was set out by <br />an AMEC field representative. Twenty -three holes were drilled encountering eight voids. An <br />approximate total of 1,150 lineal feet was drilled. As -built survey of the drill holes was performed <br />by Ames. <br />Confirmatory drilling was performed at Underground Working #4052. A drill pattern was set out by <br />an AMEC field representative. Forty -five holes were drilled encountering eight voids. An <br />approximate total of 2,250 lineal feet was drilled. As -built survey of the drill holes was performed <br />by Ames. <br />Confirmatory drilling was performed at Underground Working #4053. A drill pattern was set out by <br />an AMEC field representative. Fifteen holes were drilled encountering no voids. An approximate <br />total of 750 lineal feet was drilled. As -built survey of the drill holes was performed by Ames. <br />Grouting of missed (non -void) confirmatory drill holes was performed at Underground Workings <br />#4046, #4052, and #4053. A grout pump and laborers were used to place bentonite grout into the <br />"miss" drill holes. <br />Q Remediation <br />Remediation of Underground Working #4000 was performed with the placement of a three -layer <br />geogrid cap extending 15 feet from the working location identified during confirmatory drilling. <br />Prior to placement, the subgrade surface was inspected and accepted by an AMEC field <br />representative. Approximately 2,300 square feet of geogrid was placed (first layer). <br />Underground Working #4016 was "cleaned out" using a CAT 330 excavator. The working was <br />inspected by an AMEC field representative and approved for backfill. The native material was <br />found to be consistent and all signs of a significant working were removed. The working was <br />backfilled with structural fill in 12" lifts using a CAT excavator. The material was tamped into the <br />working using the excavator bucket. Compaction will be performed using a 10 -ton vibratory <br />smooth drum compactor when access is available. <br />A blast was performed at Underground Workings #4024, #4025, and #4026 collapsing the crown <br />pillars above the identified laterals. <br />Remediation of Underground Working #4028 was performed with the placement of a three -layer <br />geogrid cap extending 15 feet from the working location identified during confirmatory drilling. <br />Prior to placement, the subgrade surface was inspected and accepted by an AMEC field <br />representative. Approximately 14,361 square feet of geogrid was placed and accepted by an <br />AMEC field representative prior to select structural fill placement. Approximately 266 cubic yards <br />of select structural fill was then placed between each geogrid and over the third geogrid layer in 6- <br />inch compacted lifts. Prior to compaction the select structural fill material was moisture <br />conditioned using a CAT 773 water truck. Compaction of the select structural fill was then <br />performed using a 10 -ton smooth drum compactor using the static method. Four nuclear density <br />MEW Weekly Report WE 02.25.2012 <br />