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Based on the reported test results (some of these results were verbally <br />reported by John Lupo) the geomembrane performed well until a normal <br />stress equivalent to a height of 1,020 feet, at an equivalent height of <br />1,040 feet some punctures were observed and there was significant <br />particle crushing. The height of 800 feet therefore allows a significant <br />safety margin. <br />An important aspect of the puncturing behavior of the liner is the <br />condition of the foundation underlying the compacted clay liner. To <br />prevent puncturing it is essential to have a firm foundation that will not <br />settle. The whole pad area of the VLF is underlain by firm materials so <br />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 on the geomembrane and under the <br />best case the material will slide along the interface. The latter is the most <br />probable scenario as it is similar to what happens in shearbox tests at <br />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 was either almost <br />flat or in the order of 3.5:1. The effects of the foundation slope are <br />therefore not of any concern to the integrity of the geomembrane liner <br />under the high heap. <br />Based on my review and discussions I am confident that the equivalent <br />load posed by the proposed 800 feet high heap will not adversely effect <br />the composite liner system of the VLF. <br />b. Leachate Pipe System <br />The leachate pipe collection system must remain operational under high <br />heap heights to prevent the development of high fluid heads on the liner <br />system that may increase the amount of leakage through potential liner <br />imperfections. Experience shows that after about 20 percent strain the <br />leachate collection pipes can deform into a "binocular" shape. The analysis <br />presented in Appendix C.3 of the AMEC report indicates that all the pipes <br />will have sufficient capacity under the designed heap heights. It is <br />expected that some of these pipes will be deformed into binocular shapes. <br />4