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For the composite liner system the reported test results (some of these <br />results were verbally reported by John Lupo during our meeting) show <br />that the geomembrane performed well until a normal stress equivalent to <br />a height of 1,020 feet. At an equivalent height of 1,040 feet some <br />punctures were observed and there was significant particle crushing. The <br />height of 800 feet therefore allows a significant safety margin. <br />The maximum and average depths of ore placement above the PSSAs for <br />the Phase 5 expansion are listed in the table below (information provided <br />by John Lupo): <br />PSSA Maximum Ore <br />Heigh t feet Average Ore <br />Height feet Comments <br />Phase I 550 420 No change <br />Phase II 450 220 No change <br />Phase IV 700 440 Onl chan e <br />For the PSSA liner system testing was carried out to a normal load <br />equivalent to 880 feet of ore and the geomembrane did not puncture. It <br />therefore also allows a significant safety margin. <br />An important aspect of the puncturing behavior of the liner is the <br />condition of the foundation underlying the liner system. To prevent <br />puncturing it is essential to have a firm foundation below the compacted <br />clay liner that will not settle. The whole pad area of the VLF is underlain <br />by firm materials so that foundation settlement is not an issue. <br />One other aspect that was evaluated during the review is the slope of the <br />foundation in the area where the heap height is 800 feet. If the slope is <br />steep then small movements may occur along the liner interface as a <br />result of the compression of heap materials. In the worst case such small <br />movements may result in striations of various depths on the <br />geomembrane layer and under the best case the material will slide along <br />the interface. The latter is the most probable scenario as this behavior is <br />observed in shearbox tests at high normal stresses. <br />Considering the isopach information on Figure 3 of the AMEC report as <br />well as the foundation grading of the VLF (refer to Dwg 4 of the Phase IV <br />Design by Golder Associates, April 2000), the high heap heights will be <br />directly above areas where the slope of the foundation is either almost flat <br />or in the order of 3.5:1. It is therefore concluded that the foundation <br />slope will not affect the integrity of the geomembrane liner under the high <br />heap. <br />4