2016-01-14_REPORT - M1980244 (15)

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Cripple Creek & Victor Gold Mining Company Squaw Gulch VLF Phase 1 (9,550-foot Elevation Bench to Geomembrane Panel P1635) Final Report Quality Assurance Monitoring & Test Results January 2016 Project No.: 74201125N0 Page 10 2.4 Subgrade Preparation Prior to SLF placement, Ames moisture conditioned and compacted the surface of the 2014/2015 Squaw Gulch VLF with a smooth drum vibratory roller. The quality of the finished surface was maintained until SLF was placed. 2.5 Leak Detection Ames constructed approximately 3,222 linear feet of leak detection trench within the Project. The as-constructed LDS is shown on Record Drawing No. 5 in Appendix A. Detail V on IFC Drawing A260 shows a typical leak detection trench section. Ames excavated the trench to a minimum of 1-foot by 1-foot cross-sectional dimension, and at a minimum one percent slope gradient. Ames placed 40-mil smooth LLDPE geomembrane material, a layer of 12-oz/yd2 non-woven geotextile material, one 3-inch diameter perforated corrugated polyethylene (PCPE) pipe, and LDF in the trench. Ames placed approximately 120 cubic yards of LDF, 16,109 square feet of 40-mil smooth LLDPE geomembrane, 16,109 square feet of 12-oz/yd2 non-woven geotextile, 2,756 linear feet of PCPE, and 467 feet of solid DR13.5 HDPE pipe for continuation outside of the certified area. The LDS geosynthetics installation is discussed further in Section 3.2. 2.6 Soil Liner Fill Based on neat line survey, Ames placed and compacted approximately 118,405 cubic yards of SLF to the project technical specifications. Record Drawing No. 2 in Appendix A presents the as-built surface of the SLF. Ames processed the SLF from both the Cameron and Squaw borrow areas for the Project construction from February 2013 through November 2015. The borrow material was worked through a custom-designed rotary mill and screen to remove oversized material from the SLF stockpile and to uniformly condition the material prior to stockpiling. Ames continued placing SLF for the Project June 2015 and completed placement November 2015. The SLF was compacted to a minimum thickness of 12 inches by a smooth drum vibratory compactor. Amec Foster Wheeler witnessed depth verification tests performed by Ames to confirm appropriate fill thickness. Areas where the SLF thickness was found to be non-compliant with the project technical specifications were re-worked and re-tested until the area was compliant. The depth verification is discussed further in Section 4.2.3. The specified minimum density was 95 percent of the maximum dry density at -2 percent to +3 percent of optimum moisture content as determined by standard Proctor tests performed by Amec Foster Wheeler. Areas of the SLF that failed to meet the moisture density requirement were moisture conditioned, re-compacted, and re-tested until passing results were achieved.