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Cripple Creek & Victor Gold Mine <br />Valley Leach Facility Expansions <br />Detailed Design for Permitting <br />NewFields Project No. 475.0106.064 <br />September 2025 <br /> <br /> <br /> <br />Page 14 <br />4.5. Lined Pad Expansion Area <br />The lined pad expansion will begin with lining upstream of the VLF1 Phase 6 PSSA and continue <br />into the PSSA. Within the VLF1 Phase 6 PSSA, a leak detection system and composite liner systems <br />will be installed below. The lining systems are described below. <br /> <br />Lined Area Upstream of the PSSA <br />The area upstream of the VLF1 Phase 6 PSSA will be lined with 80-mil LLDPE geomembrane. This <br />liner will be tied in to the downstream 100-mil LLDPE geomembrane that will line the PSSA. <br /> <br />4.5.1. Leak Detection System <br />A leak detection system (LDS) will be installed along the alignments shown on Drawing A008. The <br />LDS will consist of geomembrane lined trenches measuring 1-foot wide by 1-foot deep. The <br />trenches will be lined with 40-mil smooth LLDPE geomembrane along the bottom, with the liner <br />extending 1-foot outside the trench crest on both sides. 12 ounce per square yard (oz/yd2) non- <br />woven geotextile will be placed along the bottom and sides of the trench before a 3-inch <br />diameter CPe pipe is placed in the bottom of the trench. The trench is then to be backfilled with <br />3/4-inch minus leak detection fill prior to wrapping the material with the geotextile. Details of <br />the LDS trench can be referenced on Drawing A020. The LDS trenches will be cut into the base <br />grading, just below the SLF of the composite liner system. The trenches will be cut so that they <br />maintain a minimum grade of 2 percent towards collection manholes, where they will be <br />monitored for solution present in the system. Details of the LDS manholes are shown on Detail C <br />on Drawing A020. <br />4.5.2. Composite Liner System <br />The composite liner system generally comprises of a 12-inch-thick SLF, with a 1×10-6 centimeters <br />per second (cm/s) or lower permeability, overlain by an 80-mil double-sided textured linear low- <br />density polyethylene (LLDPE) geomembrane with a permeability of 1.6 x 10-9 m/s assuming the <br />design hydraulic head of 2 ft is maintained (Lee, Shin, & Kim, 2018) , overlain by a minimum of <br />two (2) feet of Drain Cover Fill (DCF). This liner system configuration is consistent with the <br />construction of previous phases of VLF1 and VLF2. Based upon experience on similar projects, <br />two (2) feet of DCF is the appropriate thickness to protect the composite liner for the two (2) ore <br />types being placed on VLF2. As presented previously in the Valley Leach Facility Design Report <br />(Amec, 2011), the liner system will withstand ore loading of up to 800 feet, or 610 pounds per <br />square inch (psi) at an assumed ore density of 110 pcf.