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Cripple Creek & Victor Gold Mining Company Squaw Gulch Valley Leach Facility Design <br />surface will enclose the three 18 inch - diameter LVSCS riser pipes and associated <br />instrumentation, electrical, and piping components (provided by others). <br />4.10 High Volume Solution Collection System (HVSCS) <br />The purpose of the HVSCS is to provide a means to collect and route process <br />solutions from the OSA to the PSSA. The HVSCS for the VLF will consist of 24 inches <br />of free draining DCF, which is supplemented with a solution collection piping system <br />placed directly over the upper geomembrane liner at the base of the DCF. <br />Within the VLF area, the primary solution collection pipes will consist of three 28 -inch <br />diameter SDR 11 perforated HDPE pipes located along the base of the Squaw Gulch <br />VLF PSSA. Together, these pipes are sized to provide capacity for the maximum <br />solution application flow rate of 17,000 gpm with a factor of safety (each sized for <br />7,083 gpm) under gravity flow conditions. Primary pipe sizing calculations are <br />presented in Appendix C.3, with primary pipe perforation analyses presented in <br />Appendix C.4. Secondary solution collection pipes, which will vary in size from 8- to <br />20- inch - diameter PCPE pipe (ADS N -12, or equivalent), will direct solution collected <br />from 4- inch - diameter highway grade PCPE tertiary pipes that are on 95 -foot typical <br />centers into the primary solution collection pipes. Detailed calculations supporting the <br />pipe spacing and pipe sizing are presented in Appendix C.B. The general layout of the <br />primary, secondary, and tertiary solution collection pipes are shown on Drawing A400. <br />Solution collection pipe details are shown on Drawing A410. <br />The HVSCS pipes were sized and located to maximize solution recovery while <br />accounting for acceptable pipe deformation under 800 feet of ore depth. The piping <br />calculations assume "arching" will occur within the DCF, thereby maintaining open <br />solution flow space. The 4- inch - diameter PCPE piping spacing of 95 feet was based <br />on minimizing the hydraulic head on the liner system in the OSA to no more than 2 <br />feet, with zero slope on the foundation (a conservative assumption). The secondary <br />pipe sizes were based on full flowing conditions assuming a pipe collapse <br />configuration. <br />The primary solution collection pipes were sized as heavy- walled HDPE to allow pipe <br />deflection without collapse. Studies of flexible pipes under high loads conducted by <br />Watkins (1990) indicate that flexible pipes, like HDPE, in granular "arching" materials <br />will remain open as long as the ring deflection does not exceed the vertical strain of <br />the bedding materials and does not exceed 20 percent. Calculations presented in <br />Appendix C.3 indicate the primary solution collection pipes are computed to have a <br />crown deflection of 7 percent under an average ore height in the PSSA of 290 feet, <br />and 14 percent under the maximum anticipated ore height in the PSSA of 450 feet. <br />The computed vertical strain approximates the vertical strain in the DCF under similar <br />loading conditions. <br />Project No.: 74201125G0 Page 23 <br />1 September 2011 <br />amec° <br />