2011-11-19_REPORT - M1980244 - Laserfiche WebLink

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ame0 bedrock or pit termination. Two layers of geogrid separated by a layer of SSF was placed a minimum of fifteen feet beyond the mine working limits. SF was used to fill the underground working to the final subgrade elevation. 2.2 Site Grading Prior to SF placement, Ames conditioned and compacted the subgrade surface of the fill area. AMEC monitored the preparation of the subgrade and verified that it met project specifications. Ames graded existing slopes and placed SF so that final slopes were no steeper than 2H:1V (horizontal:vertical). In native ground, the in -situ material was scarified to a depth of approximately 6 inches. SF was compacted with a minimum of four passes by a smooth drum vibratory compactor according to the project specifications. In the 2009 and 2010 construction seasons, Ames placed approximately 2,513,001 cubic yards of SF for site grading in and around the Phase 5 VLF. Fill placement was performed within the 2011 Phase 5 VLF OSA 3rd Portion during this time. 2.3 Leak Detection System Ames constructed approximately 3,764 linear feet of LDT in the 2011 Phase 5 VLF OSA 3rd Portion, at the location shown in Record Drawing No. 2 of 5. IFC Drawing A280, Detail J, shows a typical Leak Detection Trench section. Ames excavated the trench to a minimum 1 -foot by 1 -foot cross - sectional dimension, and a minimum one percent grade. Ames placed geosynthetics, one 4 -inch diameter perforated corrugated polyethylene (PCPE) pipe, and LDF in the trench. Ames placed approximately 139 cubic yards of LDF, 18,820 square feet of 40 -mil smooth Low Linear Density Polyethylene (LLDPE) geomembrane, 15,056 square feet of 12 -ounce non -woven geotextile, and 3,764 linear feet of PCPE in the LDT. The LDT geosynthetics installation is discussed further in Section 3.2. AMEC Earth & Environmental, Inc. 2000 S Colorado Blvd 2 -1000 Denver, CO 80222 Tel 303 - 935 -6505 Fax 303 - 935 -6575 www amec corn 9