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ameO <br /> December 17, 2009 <br /> Mr. Timm Comer <br /> Manager, Environmental Resources <br /> Cripple Creek&Victor Gold Mining Co. <br /> P.O. Box 191 <br /> Victor, CO 80860 <br /> Re: Hydro-Je)Jm Program Review <br /> Dear Timm: <br /> AMEC Earth and Environmental (AMEC) has prepared this letter for the Cripple Creek&Victor Gold <br /> Mining Company(CC&V) presenting a stability review for the Hydro-JexTm program being proposed by <br /> Metal Recovery Solutions, LLC (MRS). The program, as outlined in the MRS letter dated 27 November <br /> 2009, will consist of drilling several cased borings into the Valley Leach Facility(VLF)ore heap. Fluids will <br /> then be injected into the borings at different intervals. In all cases, the borings will be completed a <br /> minimum of 100 feet above the liner surface. <br /> According to the preliminary layout of the borings provided by CC&V, the borings are to be located along <br /> the 9925 bench,with a crest set-back of approximately 20 feet. According to the MRS letter, the injection <br /> pressures into the ore heap are to be varied to be at or just below the overburden pressure. <br /> There are several case studies of injecting fluids into ore heaps to enhance recovery. From a stability <br /> standpoint, injecting fluids into ore heaps can be safely done without risking stability by carefully <br /> monitoring injection pressures. In general, the most critical conditions for fluid injection occur with <br /> injection at shallow depths. This is because of the low in situ stresses in the ore heap,which may be <br /> exceeded if injection pressures are not monitored closely. Exceeding the in situ stress at or near an ore <br /> slope, may lead to localized instability. <br /> As part of the review of the proposed injection program, AMEC analyzed the injection pressure and extent <br /> of saturation at several locations in the VLF ore heap. These data were then used to assess stability of <br /> the VLF ore slopes. To assess the injection pressures and extent of saturation, the numerical model <br /> TOUGHV2 was used. TOUGHV2 (Pruess et al, 1999) is a multi-dimensional numerical model for <br /> simulating the coupled transport of water, vapor, air, and heat in porous and fractured media. TOUGHV2 <br /> takes account of fluid flow in both liquid and gaseous phases occurring under pressure, viscous, and <br /> gravity forces according to Darcy's law. Interference between the phases is represented by means of <br /> relative permeability functions. The ore slope stability was analyzed using the program Slide 5.0 <br /> (RocScience,2008). <br /> Figure 1 presents a plan map of the VLF showing the 9925 bench. Figure 2 presents a section through <br /> the VLF that was used to assess injection and stability. It is important to note that the focus of the <br /> analyses was on the upper 115 feet of the ore heap from the 9925 bench. Fluid injection at depths greater <br /> than 115 feet, would have no effect on stability due to the large, unsaturated ore section. <br /> Prior to assessing the effect of injection on stability, a stability analysis was conducted on the section <br /> shown in Figure 2, under a no-injection scenario. The stability analysis was conducted using the same <br /> ore strength parameters that have been used for the VLF design (e.g. friction angle of 40 degrees and <br /> zero cohesion).The results of the stability analysis are presented in Figure 3, indicating a Factor of Safety <br /> (FOS)of 1.62, under a no-injection scenario. <br /> AMEC Earth&Environmental, Inc. <br /> 304 Inverness Way South,Suite 490 <br /> Englewood,Colorado 80112 <br /> Tel: (303)433-0262 <br /> Fax: (303)433-0362 www.amec.com <br /> &WROJECTS1112SE CCV COA1e-correepondencelhydro lox IeHer.doc <br />