2008-04-15_REVISION - M1980244 (256)

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~` ~ J SMITH WILLIAMS CONSULTANTS, INC. ~• in Appendix C indicate the primary solution collection pipes are computed to have a ring deflection of approximately 12 percent, which is equivalent to the vertical strain in the DCF under 590 feet of ore for the Phase 5 VLF, and 20 percent for the Phase I through IV VLF primary solution collection pipes under 800 feet of ore. The Phase I through IV solution collection pipes were sized to accommodate this level of vertical strain under full flowing conditions. In cases where the pipe strain exceeds 20 percent, the pipe flow capacities were designed based on a "binocular" cross-section. It is important to note that the solution collection pipes within Phase I, Phase II, Phase III, and Phase IV were originally designed assuming a "binocular" cross-section. Therefore, the solution collection .pipes within the existing VLF will be able to convey leach solutions, as designed, to the PSSAs. Solutions within the Phase 5 VLF PSSA will report to the solution collection sump and to the solution recovery riser system. The solution recovery riser system consists of four 24-inch- diameter steel risers that will house vertical turbine pumps. The riser layout and design details are presented in Drawings A340 to A350. The steel risers will be manifolded together to the primary HVSCS pipes to enhance solution recovery. Each riser will be constructed of stainless steel, slotted well casing and carbon steel blank casing. The screened section for each riser is • 20 feet long. Each of the riser segments will be welded together to form a uniform column. The riser pipes and riser base plates-have been designed to withstand the down-drag forces resulting from the settlement of 45 feet of ore, the nominal ore depth at the PSSA sump location. To reduce some of the down-drag forces, the riser design includes compression joints. The compression joints allow settlement and compression to occur in the riser without transmitting the down-drag force through the entire riser column. Compression joints are standard technology for deep-water production wells and were used in the Phase IV PSSA riser system. 4.10 Appurtenant Structures Access roads have been incorporated into the design to provide for small truck traffic access around the perimeter of Phase 5 VLF and construction roads within the VLF extension area. A 15- to 20-foot-wide road (typical) in additiori to 6 feet for a safety berm and 6 feet for a small drainage ditch has been incorporated into the design. The access roads were designed for small vehicular traffic only. Layouts of the access roads are presented in Drawing A220. 4.11 Reclamation/Closure At closure, the Phase 5 VLF will need to be detoxified via rinsing. After detoxification, the • Phase I, II, III, IV, and 5 VLF side slopes will be regraded to overa112.5H:1 V slopes. The reclaimed Phase 5 VLF configuration is shown on Drawing A600. S:\PROJECTS\1125 CCBV PHASE 5 VLF\H2 - DESIGNV\REQUA VLF\VLF PHASE 5 FINAL REPORT V2.DOC 27