2012-02-28_REVISION - M1980244 (65)

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Cripple Creek & Victor Gold Mining Company Squaw Gulch Valley Leach Facility Design flow away from disturbed areas, as needed. The post closure surface water diversions are located along the margins of the reclaimed VLF slopes (refer to Drawing A610). Operational and permanent surface water diversion channels have been sized to divert upgradient surface water generated from the 100 - year /24 -hour storm event. Temporary surface water diversion channels have been sized to divert upgradient surface water generated from the 25- year /24 -hour storm event. 1.2 Scope of Work The purpose of the AMEC Earth & Environmental (AMEC) work, reported herein, was to provide CC &V with engineering services for the design of an additional VLF. This document supports the engineering design and CC &V's permitting activities. This document includes the following: • Site characterization for the VLF area, including foundation characterization and identification of borrow sources; • Results of laboratory testing of selected representative materials for VLF design; • Review of historical underground workings information and recommendations for foundation remediation in areas of underground workings within the VLF area; • Design and layout for the VLF in two phases; • Proposed grading for the future mill platform adjacent to the VLF; • Design of a temporary tunnel to facilitate construction access across existing Highway 67;Engineering analysis to design the VLF foundation and drainage, including an evaluation of the slope stability for the ore depths and VLF footprint; • Water balance calculations for the VLF PSSA sizing; • Design of the PSSA riser system; • Hydraulic design of the stormwater diversion channels in the VLF area; • A design report suitable for management and agency review; and • Technical Specifications for the VLF and ancillary features. 1.3 VLF Design History In October 1993, Golder Associates Inc. (Golder) developed a design report for the Phase I and Phase II components of the VLF titled, "Permitting Level Design Evaluation of the Expansion of the Mining and Ore Processing Facilities: Cresson Project," which was presented as an attachment to Amendment No. 6 to Permit M- 1980 -244 filed with the Office of Mined Land Reclamation (OMLR) (CC &V 1993a). In January 1997, Golder developed a design report for a 620,000- square -foot valley leach extension in the area of the former site of the Carlton Mill titled, "Cresson Project, Phase II Heap Leach Pad Expansion Design," which was submitted by CC &V to the OMLR with a March 20, 1997, letter titled, "Cresson Project; Permit M- 1980 -244: Technical Revision for Expansion of Phase II of Cresson Project Valley Leach Facility." In July 1998, Golder developed a design report for Phase III titled, "Cresson Project; Valley Leach Facility Expansion, Phase III Design," which was presented as Volumes II and III of Amendment No. 7 to Permit M- 1980 -244 filed with the OMLR (CC &V Project No.: 74201125G0 Page 4 1 September 2011 amec0