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C] <br />8.1 General <br />This section discusses the puncture protection of the geomembrane liners in both the <br />existing and future modules to resist the additional loading from the vertical expansion. <br />Puncture protection of the geomembrane is a design consideration when coarse-grained <br />materials with angular surfaces are used as leachate collection layers above the <br />geomembrane liners. As noted previously, Modules 1 and 3 make use of a geonet <br />drainage layer; therefore, puncture protection of the geomembrane within these modules <br />is not a concern. The puncture protection of the existing geomembrane in Module 4 and <br />geomembranes in the future modules is discussed in this section <br />The puncture protection calculations were performed based on procedures outlined in <br />Wilson-Fahmy et al. (1994) and Koerner (1998). <br />0 <br />8.2 Existing Geomembrane Liner in Module 4 <br />Rounded gravel was specified for the leachate drainage layer in the original design for <br />Module 4. Therefore, a geotextile protection layer was not used in the original design. <br />The gradation (see Attachment G-1) for the drainage layer used in Module 4 shows <br />maximum grain size of 3/8 inch or 9.5 millimeters (mm). <br />The originally designed maximum waste height above Module 4 is 130 feet. The final <br />grading plan for the vertical expansion of NCRC&SL shows a maximum waste height of <br />approximately 241 feet above the existing Module 4 liner system. Because of the <br />increase in waste height, a puncture protection calculation has been performed to <br />determine if the geomembrane can withstand the additional loading without puncturing. <br />The puncture protection calculations are presented Attachment G. Although rounded <br />gravel was specified, to be conservative, sub -rounded gravel has been assumed in these <br />calculations. The calculations show that the geomembrane can support the loading from <br />the vertical expansion without a geotextile cushion. <br />Geotechnical Analyses for NCRCSL Department of Public Works/Solid Waste <br />Shaw Environmental, Inc. County of San Joaquin, December 12, 2007 <br />8-1 <br />