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Cripple Creek & Victor Gold Mining Company Squaw Gulch Valley Leach Facility Design <br />Solution within the PSSA will report to the solution recovery riser system. The solution <br />recovery riser system consists of four 24- inch - diameter steel risers that will house <br />vertical turbine pumps. The riser layout and design details are presented in Drawings <br />A330 to A350. The steel risers will be manifolded together to the primary HVSCS pipes <br />to enhance solution recovery. Each riser will be constructed of stainless steel, slotted <br />well casing and carbon steel blank casing. The screened section for each riser is a <br />minimum of 22 feet long. Each of the riser segments is welded together to form a <br />uniform column. The riser pipes and riser base plates have been designed to <br />withstand the down -drag forces resulting from the settlement of 110 feet of ore, the <br />nominal ore depth at the PSSA sump location. Riser pipe design calculations are <br />presented in Appendix C.5. To reduce some of the down -drag forces, the riser design <br />includes both compression joints and a geomembrane sleeve. The compression joints <br />allow settlement and compression to occur in the riser without transmitting the down - <br />drag force through the entire riser column. Compression joints are standard technology <br />for deep -water production wells and were used in the Phase IV and Phase 5 PSSA <br />riser systems. The geomembrane sleeve will be added to the upper section of each <br />riser. The purpose of the geomembrane sleeve is to reduce the frictional force <br />between the ore and the riser pipe, thereby reducing the down -drag force on the riser <br />column. Geomembrane sleeves have been used in the design of the Phase 1, II, IV, <br />and 5 risers. <br />4.11 Potential for Filtered Tailings Storage <br />AMEC recently completed an evaluation for the potential storage of agglomerated <br />filtered tailings within the existing VLF. The results of this evaluation are presented in <br />Appendix I and represent an analysis in which the agglomerated tailings break down to <br />the original constituent gradation. Based on the above referenced stability evaluation, <br />there is no impact to global stability when incorporating any form of filtered tailings (i.e. <br />agglomerated or non - agglomerated) within either VLF (AGVLF or SGVLF) when <br />integrated as outlined in the above memorandum referenced in Appendix I. <br />CC &V proposes the operational flexibility to store agglomerated filtered tailings from <br />the mill within the AGVLF near the end of VLF operations (i.e., at the surface of the <br />heap) and within the SGVLF over the life of the facilities. Based on topographic affects <br />on the ore stacking plan and the designed minimum leach block area, the current <br />maximum ore height is proposed at approximately 700 feet, while the design <br />presented herein provides capacity for a load of up to 800 feet of ore. As such, <br />agglomerated filtered tailings may be placed within the upper 100 feet of the AGVLF <br />cross - section (or alternatively ore placed to a smaller top surface area than currently <br />planned) and within the entirety of the SGVLF. As a matter of prudent ore placement <br />practice on the VLFs, agglomerated filtered tailings shall not be placed within 25 feet of <br />the crest of any ore lift to minimize the potential for localized ore sloughing by blending <br />tailings close to the ore face. <br />Project No.: 74201125G0 Page 24 <br />1 September 2011 <br />amec' <br />