2009-07-07_REPORT - M1980244 (6)

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Cripple Creek & Victor Gold Mining Company Cresson Project ameO Quality Assurance Monitoring and Test Results Load Out Bin Relocation July 7, 2009 4.2.2 Subgrade Preparation AMEC monitored subgrade preparation, including verification that Ames compacted the subgrade with a smooth drum vibratory compactor. AMEC verified that Ames removed protruding rocks from the subgrade surface prior to SLF placement. AMEC verified that the subgrade surface was moisture conditioned, smooth, and unyielding prior to SLF placement. 4.2.3 Site Grading AMEC monitored site grading. Due to the gradation of the SF used for site grading, the compaction of the fill could not be tested with a nuclear density gauge (that is, the fill had greater than 30 percent by weight larger than three - quarter inch particle size). AMEC verified that the maximum particle size of the fill did not exceed 24 inches, and that lifts were no thicker than one and one -half times the maximum particle size. When SF was placed for slope reduction, AMEC verified that Ames scarified in -situ materials prior to fill placement. AMEC verified that Ames made a minimum of four passes with the smooth drum vibratory roller compactor. 4.2.4 Soil Liner Fill Field testing included monitoring of placement and preparation of SLF for geomembrane deployment, testing in -place moisture and density with a nuclear gauge, and monitoring depth verification. 4.2.4.1 Field Monitoring AMEC observed SLF placement to verify lift thickness, adequate compaction, acceptable moisture conditions, final compacted thickness, and suitability for geomembrane deployment. AMEC identified angular particles on the fill surface, ruts, and desiccation cracks, and brought these features to the attention of Ames for repair. When necessary, AMEC verified these repairs were completed. Where necessary, Ames laborers placed fines from their SLF processing plant or from temporary piles of fine SLF to smooth and re- compact the fill surface in areas that were observed to be rough or inadequate, as discussed in Section 6.1.2. AMEC and Lonestar approved the final surface of the SLF prior to geomembrane deployment. 4.2.4.2 Moisture - Density Test Results AMEC performed a total of 6 in -place moisture - density tests of SLF. AMEC compared results of the field moisture content and density tests to the Proctor dry density and optimum moisture content values of material with similar gradation and plasticity characteristics. Proctor dry density and optimum moisture content values for samples with greater than ten percent plus three - quarter -inch material were corrected according to ASTM D4718 to facilitate direct comparison to nuclear density values. The moisture - density testing frequency of approximately SAPROJECTS\1125E CCV CQA \H3 - CONSTRUCTION \LOB CERT REPORT\REPORT BODY\LOB CERT REPORT 2009.07.01.DOC 13