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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 /> March 2024 <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 /> 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 1x10-6 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. <br /> 4.6. Solution Collection System <br /> 4.6.1. High-Volume Solution Collection System <br /> A system of pipes called the High-Volume Solution Collection System (HVSCS) will collect and <br /> direct process solution within the facility to either ADR2 or a PSSA. The HVSCS pipes, as shown <br /> on Drawing A017, are located within the DCF directly above the geomembrane liner and consist <br /> • of secondary perforated CPe pipes varying in size from six (6) to twenty-eight (28) inches in <br /> Page 14 <br />