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Cripple Creek & Victor Gold Mining Company September 2, 2004 <br />Mr. Kevin Riley -3- 043-2251 <br />cohesion was selected to represent the soil liner/geomembrane interface. These <br />sheaz strength parameters are considered conservative, assuming use of 80-mil <br />single-sided textured geomembrane. Higher shear strength parameters were <br />obtained for other liner types, as reported in Amendment No. 8. <br />• Foundation Material: For the stability analyses, the subgrade was assumed to consist of <br />Structural Fill. For the stability analyses, the foundation material was modeled with an angle <br />of internal friction of 40 degrees and no cohesion. <br />• Piezometric Data: The piezometric head was modeled as 1 foot above and parallel to the <br />lined surface, which is consistent with the conditions used in Amendment No. 8. <br />The cross-section selected for the stability analyses intersects the existing Phase II liner system and <br />the proposed liner extension. Both circular and non-circular failure surfaces were considered in the <br />analyses. Excluding surlicial "infinite slope" or veneer-type failure surfaces, the minimum factors of <br />safety for static and pseudostatic loading are presented in Table 1. <br />TABLE 1 - Summary of Stability Analyses <br />II <br /> <br /> <br /> <br /> <br />Section Anal zed <br />Static Conditions Pseudo-Static Conditions <br />0.14 <br />Critical active/passive wedge failure FS = 1.7 FS = 1.5 <br />alon eomembrane interface Non-circulaz surface Non-circular surface <br />Critical failure through ore slope FS = 1.5 FS = 1.2 <br /> Circular surface Circular surface <br />As shown in Table 1, the stability section indicates that the static factor of safety is 1.5 or greater, and <br />the pseudo-static factor of safety is 1.0 or greater for design acceleration of 0.14g. It is important to <br />note that the factor of safety values reported represent the operational ore sideslope of 1.6H:1V. At <br />reclamation, the ore sideslopes will be regraded to a flatter sideslope of 2.SH:1 V, which will increase <br />the overall long term stability of the facility. <br />' Water Balance <br />The Phase IV water balance (Golder 2002) was revised to include the proposed 68,700 sf of liner area <br />' resulting from the modified Amendment No. 7 VLF. Based on the Phase N water balance (Golder <br />2002), which was the basis for the revised water balance, excess solution from the Phase I and Phase <br />II PSSA is routed to the External Storage Pond. The increased area of the proposed VLF liner system <br />' was found to have a negligible effect on the water balance. The maximum amount of excess solution <br />(which includes the 100-year storm event plus 12 hours of instantaneous draindown) is approximately <br />19.3 million gallons (MG). The External Storage Pond has a capacity of approximately 19.4 MG <br />' with 3 feet of freeboard, therefore there is sufficient capacity in the External Storage Pond to account <br />for the modified VLF boundary. <br />' Construction Specifications <br />Construction of the modified Amendment No. 7 Phase IUIII VLF liner will be conducted according to <br />the project specifications provided in Amendment No. 8. Applicable sections of the project <br />' specifications include: <br />' cwa~zs~w~oo~oaa~r-ovozoa~ooavsi.oioo.~is~zHOanmi-ovozoa.e«Golder Associates <br />