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am e <br />• Track Mounted Drill Rigs. <br />Weather data for the 2010 Phase 5 VLF construction activities from the period of January <br />2009 through November 2010 are presented in Table 2. <br />2.1 Underground Workings Remediation <br />Historic underground workings within the footprint of the Phase 5 VLF were remediated <br />following the recommended remediation plans presented in Drawing A290 of the IFC <br />Drawings. <br />A summary of the underground workings remediation is presented in Table 4. This table <br />shows the working identification, location (northing and easting), and type of working, <br />remediation quantities, and comments. The following provides a summary of the general <br />remediation methods for the underground workings within the Phase 5 VLF footprint. <br />0 2.1.1 Remediation of Shafts, Stopes, and Shallow Surface Pits <br />The following is the general approach used to remediate isolated shafts and shallow surface <br />pits: <br />• For open workings where the depth to competent bedrock is less than <br />7 feet to the final SLF subgrade surface, the excavations were backfilled <br />with CSB to approximately 10 feet below the finished surface grade. The <br />surface of the CSB was compacted using the shovel from a <br />CAT excavator. A 3-foot minimum CP was cast into the shaft and <br />allowed to cure for a minimum of 7 days. A minimum 7-foot thick layer of <br />CR was then placed onto the CP. SF was then placed to the final grade, <br />as needed. In some cases, the excavation did not require placement of <br />CSB prior to placement of the CP and CR. <br />• For open workings where the depth to competent bedrock was greater <br />than 7 feet to the final SLF subgrade surface, the excavations were <br />backfilled with CSB to 3 feet below the soil/bedrock interface. The <br />surface of the CSB was compacted using the shovel from a CAT <br />excavator. A 3-foot minimum CP was cast into the shaft and allowed to <br />cure for a minimum of 7 days. A minimum 7-foot thick layer of CR was <br />AMEC Earth & Environmental, Inc. <br />2000 S. Colorado Blvd 2-1000 <br />Denver, CO 80222 <br />Tel 303-935-6505 <br />Fax 303-935-6575 www.amec.com 10