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S Z <br />SMITH WILLIAMS CONSULTANTS, INC. <br />• <br />4.6.2 Phase 5 VLF PSSA <br />The Phase 5 VLF PSSA will be constructed as an internal solution storage area within the Phase <br />5 VLF area. The PSSA will be formed by constructing a PSSA containment embankment <br />between the Phase IV VLF and Squaw Mountain. The PSSA layout and details are presented on <br />Drawings A300 through A335. <br />The liner system for the PSSA will consist of the following: <br />^ Inside of the PSSA the liner system will consist of 1 foot of SLF overlain by a 100- <br />mil textured (single-sided with textured side down) LLDPE bottom geomembrane <br />overlain by 3 feet of LVSCF overlain by a 100-mil smooth LLDPE top geomembrane <br />overlain by 2 feet of DCF. A textured LLDPE geomembrane was selected for the <br />bottom liner as it provided for higher interface shear strength than smooth LLDPE <br />geomembrane. <br />^ On the PSSA embankment, the embankment slope is graded at 2.SH:1 V in the <br />embankment fill. The liner system on this slope consists of 1 foot of SLF overlain by <br />100-mil textured (both sides) LLDPE bottom geomembrane, 3 feet of LVSCF, a <br />100-mil textured (both sides). LLDPE top geomembrane, and 2 feet of DCF. <br />These PSSA liner systems are consistent with those used in previous Amendments. <br />4.7 Leak Detection System <br />A leak detection system, composed of a geomembrane-lined 1-foot-by- l -foot deep trench, has <br />been designed to be installed along alignments identified in Drawing A220, beneath the SLF <br />component of the composite liner. The leak detection trenches will be lined with 40-mil smooth <br />LLDPE geomembrane on the bottom and one side as with previous VLF designs. A 12-oz/yd2 <br />nonwoven geotextile will then be placed in the leak detection trench and wrapped around a 3- <br />inch diameter perforated corrugated polyethylene pipe and 3/4-inch minus leak detection fill. <br />The trenches will be excavated on a typical grade of 1 percent.toward a sump located at the edge <br />of the VLF. Typical details for the leak detection system are illustrated in Drawing A260. <br />4.8 Low Volume Solution Collection System (LVSCS) <br />The Phase 5 VLF PSSA has been designed to include a LVSCS composed of 1-inch minus <br />LVSCF layer, which is installed between the upper 100-mil LLDPE geomembrane and the lower <br />100-mil LLDPE geomembrane. The thickness of the LVSCSF layer will be 3 feet within the <br />S:\PROJECTS\1125 CCBV PHASE 5 VLF\H2 - DESIGNV~REQUA VLF\VLF PHASE 5 FINAL REPORT V2.DOC 2S <br />