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0 <br />intervals in the overburden stockpiles to the north and northwest of the excavation. <br />Samples were obtained by excavating with a backhoe into the stockpiles at depths <br />of 3 to 8 feet. Samples were returned to our laboratory for testing. Similar soils were <br />combined and tested for gradation, classification and maximum density <br />determination by Proctor method. Table A-1 presents test results and <br />classifications. Laboratory compaction test results and gradations are presented <br />in Figs. A-1 to A-6. <br />We obtained two samples of the bedrock at the floor of the Arvada Reservoir <br />Pit for testing of the properties of the clay-shale materials for use in the core of the <br />zoned earth dam. Samples were returned to our laboratory for classification and <br />maximum density determination by Proctor method. We also performed a field <br />permeability test via the Packer method. Logs of these borings are presented in <br />Figs. 2 and 3. <br />Slope Stability Analysis -Perimeter Embankment <br />Two material types were selected for slope stability analysis for the perimeter <br />embankment, which appear to represent a range of materials that were predominant <br />in the overburden stockpiles. Each material was remolded at 95 and 98 percent of <br />maximum standard Proctor dry density (ASTM D 698) near optimum moisture <br />content. Strengths were determined by triaxial testing, in a consolidated undrained <br />with pore pressure condition. The remolded samples were tested at confining <br />pressures of 5, 10 and 20 psi. Triaxial test results are presented in Figs. A-7 and A-8. <br />Slope stability analysis was conducted using the Slope W software program. <br />A cross section of the Arvada Reclamation Pit interior slope configuration is shown <br />on Fig. 4. <br />Permeability testing was conducted at Arvada Reservoir to evaluate the <br />permeability of the proposed embankment material. The highest permeability tested <br />was 2.1 x 10'~ cm/sec. The lowest permeability was 3.1 x 10$ cm/sec. If the <br />embankment ever became saturated and there was a rapid drawdown event (1 ft/day) <br />the water in the embankment soils would not drain significantly. Therefore, after <br />completely draining the reservoir the materials would remain saturated. We modeled <br />this event by placing the phreatic surface at maximum water level and following the <br />surface of the embankment slope. In our opinion, this evaluates a worst case <br />scenario. A crumb dispersion test was performed on remolded overburden material <br />and indicated that no dispersion was evident. <br />According to Mike Applegate, criteria from the State Engineers office for <br />zoned earth dams require a minimum factor of safety of 1.5 for normal operating <br />reservoirs in a steady state condition, 1.2 for rapid drawdown conditions and 1.0 for <br />seismic conditions. We modeled the seismic stability analysis by using a 10 percent <br />AGGREGATE INDUSTRIES <br />ARVADA RECLAMATION PIT <br />CTL/TJOB NO. 32,637 2 <br />