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• April 2009. AMEC accepted a variance in the plastic index (PI) of the <br />Fine Shaft Backfill (FSB), Pipe Bedding Material (PBM), and Granular Fill <br />Material (GFM). The PI of these materials was increased from 5 to 15. <br />The increase in PI is considered insignificant by AMEC based on <br />experience with similar projects and the required performance of these <br />materials. <br />• July 2010. AMEC submitted a change in the Soil Liner Fill (SLF) <br />specification, increasing the fines content (minus 200 sieve) from 50 to 65 <br />to allow blending of materials. In addition, the requirement to conduct <br />permeability tests on in -field samples was modified to allow permeability <br />of stockpile samples. The frequency of permeability testing was increased <br />from one test per 5,000 cubic yards to one test per 4,000 cubic yards. <br />1.5 Record Survey Documentation <br />Ames Construction of Aurora, Colorado, provided the Record Drawings for the activities <br />associated with the 2011 Phase 5 VLF OSA 3 Portion. A Colorado Registered Land <br />Surveyor prepared the drawings. The Record Drawings are presented in Appendix A. The <br />Surveyor's certificate is presented in Appendix F. Ames also provided locations for SLF <br />density tests, SLF depth checks, geomembrane panels, and destructive tests, which were <br />used by AMEC to develop test summaries and the geomembrane panel layout drawing <br />(Record Drawing No. 4 in Appendix A). <br />1.6 Certification Boundary <br />amec <br />Figure 2 presents the boundary of the 2011 Phase 5 VLF OSA 3 Portion that is being <br />certified in this report. The certification boundary coincides with the limits of the 2011 Phase <br />5 VLF OSA 3 Portion liner system and includes leak detection system construction; site <br />grading; subgrade preparation; SLF placement and compaction; primary 80 -mil single -sided <br />textured geomembrane installation; installation of High Volume Solution Collection System <br />pipes; and DCF placement. <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 6 <br />