2014-02-07_REPORT - M1980244 (7)

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Cripple Creek & Victor Gold Mining Company Mill Site Earthworks Project Final Report ameO Quality Assurance Monitoring &Test Results January 31, 2014 2.2 Secondary Underdrain Ames constructed approximately 1,768 linear feet of Secondary Underdrain in the Mill Site Earthworks Project. Record Drawing No. 2 of 4 shows the location of the Secondary Underdrain. The cross sectional dimension of the secondary Underdrain was nominally 4 feet wide by 2 feet deep, providing a cross sectional area of 8 square feet, as shown on IFC Drawing No. A320 Detail L. Ames excavated each Secondary Underdrain trench to the minimum dimensions, and placed geotextile and UFM in the trench. Ames placed SSF over the geotextile to a minimum depth of 6 inches. The Secondary Underdrain geosynthetic installation is discussed further in Section 3.1. Approximately 524 cubic yards of UF, 131 cubic yards of SSF, and 21,216 square feet of geotextile were used to construct the Secondary Underdrains. 2.3 Site Grading Prior to OVF placement, Ames moisture conditioned and compacted the subgrade surface of the fill area. AMEC monitored the preparation of the subgrade and verified it met Project Specifications. Ames graded existing slopes and placed OVF so that final slopes were no steeper than 2H:1 V (horizontal:vertical). On native ground, the in situ material was scarified to a depth of approximately 6 inches. OVF was compacted with a minimum of four passes by a smooth drum vibratory compactor according to the Project Specifications. Ames placed approximately 6,056,285 cubic yards of OVF for site grading in and around the Mill Site Earthworks Project. 2.4 Subgrade Preparation Prior to SLF placement, Ames moisture conditioned the surface of the Mill Site earthworks footprint and compacted the entire surface with a smooth drum vibratory compactor, according to the Project Specifications. The quality of the finished surface was then maintained until SLF was placed. 2.5 Soil Liner Fill Based on neat line survey, Ames placed and compacted approximately 54,147 cubic yards of SLF to Project Specifications. Record Drawing No. 3 of 4 in Appendix A presents the as -built surface of the SLF. Ames processed the SLF for the Mill Site Earthworks Project construction from June 2012 through September 2012. The borrow material was worked through a custom - designed rotary mill and screen to remove oversized material from the SLF and to uniformly condition the material prior to stockpiling. 9