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<br />Memo to Berhan Keffelew <br />CRESSON Haul Road Thickness <br />page 2 <br />analysis it was determined that a factor of safety below unity resulted <br />for the case involving abrupt shear loading of the drain cover fill against <br />the geomembrane. The solution in this instance was to specify that <br />equipment would not make pivot turns, abrupt braking, or attempt to over <br />push material. This was plausible in general placement of the cover fill in <br />open areas. <br />In the situation now under consideration the haul trucks commonly enter <br />the dump area and complete as abrupt a circle turn as possible. This is <br />done to minimize the area required for stockpiling the drain cover <br />material. This will be particularly necessary in the more confined areas <br />of the saturated sump area of Phase II. The trucks do not want to back to <br />complete their circuit, because this consumes time and requires <br />significant effort. As a result there is a significant likelihood that <br />precipitous and abrupt turns will occur repetitively in the circular truck <br />dumping areas. <br />Following up on AI Sorenson's suggestion, I completed a rudimentary <br />dynamic shear loading analysis for the side dump haul trucks. This <br />analysis was labeled "Case 4" in Appendix D of the March 1, 1996 <br />submittal completed by Golder Associates on behalf of CC&VG. I used <br />dimensions for the side dump truck tire placement which John Hardaway <br />and I verified at the site on Friday, August 30, 1996. As in the earlier <br />dozer analyses, my analysis resulted in a sub-unity {0.9) factor of safety <br />result for shear between the drain cover fill and the geomembrane, under <br />the 50% dynamic shear convention suggested by Caterpillar, Inc. This <br />suggests that shear failure of the drain cover fill could occur under the <br />dynamic loading of an abruptly turning or stopping loaded side-dump truck. <br />Conclusion <br />Based upon my review of CC&VG's submittals, my visit to the site, and my <br />interpretation of the intended side-dump truck operation, I offer the <br />following recommendations for approval of CC&VG revision request. <br />