2012-08-24_REPORT - M1980244 (11)

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ANk "M and it was decided to backfill the stope with structural fill and a concrete plug will be installed in the shaft. The working was backfilled to approximately 10 feet from the existing ground surface with structural fill using a CAT 330 excavator and compacted using a 10 -ton vibratory smooth drum compactor. The sides of the shaft were then shaped with 05V:1 H slopes preparing the shaft for concrete plug installation. An AMEC field representative observed the backfill and inspected the shaped upper portion of the shaft. It was found to be acceptable for concrete placement. Remediation of Underground Working #4025 was performed using a John Deere excavator to place coarse shaft backfill in the open shaft. The working was backfilled to approximately 10 feet from the existing ground surface. The sides were then shaped with 05V:1 H slopes preparing the shaft for concrete plug installation. An AMEC field representative observed the backfill and inspected the shaped upper portion of the shaft. It was found to be acceptable for concrete placement. Underground Working #4026 was investigated using a CAT 330 excavator and observation was performed by an AMEC field representative. Excavation of the area was performed and it was found to be a shallow surface working. The native material was found to be consistent and all signs of a significant working were removed. The working was backfilled with structural fill in 18" to 24" lifts using various CAT dozers. Each lift was moisture conditioned using a tandem axle water truck (when necessary) and compacted using a 10 -ton vibratory smooth drum compactor, passing over the entire fill surface at least 4 times (method compaction technique was applicable). A blast was performed at the remaining portion of Underground Workings #4031 collapsing the crown pillar above the identified laterals. A John Deere excavator was then used to excavate the collapsed crown pillar from the working. A John Deere 850 excavator was then used to place coarse shaft backfill material back in the working. The material was placed in small lifts and bucket tamped until access for a CAT 563 vibratory smooth drum compactor was achieved. The material was then placed in 18" to 24" lifts. Each lift was moisture conditioned using a tandem axle water truck (when necessary) and compacted using a 10 -ton vibratory smooth drum compactor, passing over the entire fill surface at least 4 times (method compaction technique was applicable). An AMEC field representative observed the remediation of the underground working. Placement of a three -layer geogrid cap extending 15 feet from the working location identified during confirmatory drilling. Approximately 10,500 square feet of geogrid was placed and accepted by an AMEC field representative prior to select structural fill placement. Approximately 250 cubic yards of select structural fill was then placed over the previously installed geogrid layer in a 6 -inch compacted lift. Prior to compaction the select structural fill material was moisture conditioned using a CAT 773 water truck. Compaction of the select structural fill was then performed using a 10 -ton smooth drum compactor using the static method. One nuclear density test was performed with results passing. Moisture - density relations were performed in accordance with ASTM D698 -07. The remaining portion of the working to receive geogrid will be remediated when the geogrid shipment is received. Remediation of Underground Working #4044 was performed The working was backfilled to approximately 10 feet from the existing ground surface with structural fill using a CAT 330 excavator. The sides of the shaft were then shaped with 05V:1 H slopes preparing the shaft for concrete plug installation. An AMEC field representative observed the backfill and inspected the shaped upper portion of the shaft. It was found to be acceptable for concrete placement. MEW Weekly Report WE 03.24.2012