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• iii iiiiiiiiiiiiiiii <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />131 3 Sherman 51., Room ? 15 <br />Dern er, Colorado 80'_03 <br />Phone: (3031 H66-7567 <br />FA%:13031 832-8106 <br />DATE: September 3, 1996 <br />TO: Berhan Keffelew <br />FROM: Allen Sorenson <br />I~~~~ <br />DEPARTMENT OF <br />NATURAL. <br />RESOURCES <br />Roy Romer <br />Governor <br />lames 5. Lochhead <br />Executive Director <br />Michael B Long <br />Division Direc Wr <br />RE: Minimum Thickness for Haul Roads Constructed on Geomembrane, <br />Cripple Creek and Victor Gold Mininq Company, Cresson Project, <br />Permit No. M-80-249 <br />In accordance with your request, I have reviewed the submittal from <br />Cripple Creek and Victor Gold Mining Company (CCVG) dated 8/26/96. In <br />this submittal, CCVG, through their consultant Golder Associates, provides <br />a demonstration that the static load imposed on the geomembrane is <br />equivalent for a CAT 773B on a 5 foot thick road and a side dump tractor- <br />trailer on a 3.5 foot thick road. The maximum static load imposed on the <br />geomembrane in either case is estimated by Golder Associates to be 5.1 <br />psi. The concern that I have with the analysis provided by CCVG is with <br />their assumption that equivalent static loadings will provide equivalent <br />protection to the geomembrane. Static loading would not be the critical <br />criteria to be considered, after all, the low volume solution collection <br />fill-geomembrane-drain cover fill cross section was subjected to a static <br />load of 385 psi during pressure testing. The concern with the roadway <br />thickness should appropriately be related to dynamic and shear loads that <br />may be imposed on the geomembrane by the truck traffic, and CCVG should <br />be required to demonstrate that the geomembrane is not subjected to <br />increased dynamic or shear loads under a decreased haul road thickness <br />configuration. <br />cc: Jim Pendleton <br />Jim Dillie <br />C:\WP51\CRESSON.59 <br />