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5 ~ <br />SMITH WILLIAMS CONSULTANTS, INC. <br />4.0 Valley Leach- Facility (VLF) Design <br />4.1 General <br />The Phase 5 VLF design is consistent with the previous designs approved by the MLRB and <br />DRMS, and implemented by CC&V for the existing VLF. The Phase 5 VLF design can be <br />summarized as follows: <br />^ . .Extension of the VLF to the north and east of Phase IV, along Squaw Mountain and <br />the AGOSA, increasing the available ore storage area. <br />^ Development of a dedicated PSSA for the Phase 5 VLF extension. The PSSA would <br />be formed along the eastern side of the Phase IV VLF, site grading, and a <br />containment berm at the southern edge of the VLF. <br />^ Increasing the ore height within Phase I through IV VLF from 590 feet (Amendment <br />No. 8) to an approximate maximum of 800 feet. The maximum ore height for Phase <br />5 is 590 feet. <br />• Using lined 2H:1 V slopes within the VLF, in localized areas where stability of the <br />facility will not be affected. <br />This section describes the design for Phase 5 VLF including foundation preparation and <br />installation of the underdrain system, leak detection system, liner system, high-volume solution <br />collection system (HVSCS), and low volume solution collection systems (LVSCS). Design <br />criteria used for the Phase 5-VLF were presented in Section 1.3 and are discussed in more detail <br />in the following sections: <br />Phase 5 VLF is designed to be constructed to the planned ore depth and ultimate limits shown on <br />the drawings, based on the design criteria and analyses presented in this report. The VLF is <br />designed as a closed system where leach solutions are contained within the lined area. Leach <br />solutions and precipitation volumes generated during the 100-year/24-hour design storm event <br />combined with other maximum operational and climatic events will be contained within the <br />existing double geomembrane-lined internal Phase I PSSA, Phase II PSSA, Phase IV PSSA, the <br />lined Phase UIUIII ESP, and the proposed double geomembrane-lined internal Phase 5 VLF <br />PSSA. <br />The quality of the constructed VLF is a very important aspect of this project. Qualified <br />_ personnel under the supervision of an experienced professional engineer registered in the State of <br />S:\PROJECTS\7725 CCBV PHASE 5 VLF\H2 - DESIGNWREQUA VLF\VLF PHASE 5 FINAL REPORT V2.DOC 20 <br />