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• • iiiiiiiiiiiiiiuiiii <br />999 <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Depadmenl of Natural Resources <br />1313 Sherman 51., Room 215 <br />Dem~er, Colorado 80203 <br />Phone: 13031 866-3567 <br />FAX: (30J) 832-8106 <br />DATE: June 25, 1996 <br />TO: Berhan Keffelew <br />FROM: Allen Sorenson ~~ <br />RE: Hentonite Amended 8oi1 <br />Mininq Company, Cresson <br />~~ <br />DEPARTMENT OF <br />NATURAL <br />RESOURCES <br />RoY Rnmer <br />Governor <br />lames S Lochhead <br />EtecWive DueUOr <br />Michael B. Long <br />Divi stun D~reaor <br />Liner, Cripple Creek and victor Gold <br />Project, Permit No. N-80-244 <br />It is my understanding that Cripple Creek and Victor Gold (CCVG) will be <br />providing a technical revision to permit bentonite amendment of soil liner <br />fill for use in the Phase II Leach Facility installation. It my further <br />understanding that the bentonite component of the soil liner fill is <br />proposed to be approximately 2 percent by dry weight. The following <br />issues will have to be addressed by the technical revision: <br />1. CCVG must specify the target percentage of bentonite, by dry weight, <br />to be blended into the soil liner fill (percent bentonite = <br />(Wgentonite-Wsoil)x100). Decreases in permeability of a bentonite amended <br />Boll drop-off rapidly above 2 or 3 percent bentonite. CCVG must then <br />specify a method for mixing the bentonite and the soil to the specified <br />percentage, and for thoroughly blending the mixture. This procedure <br />should also have the capability to break-up any clods that may form. <br />2. CCVG must conduct all required soil tests, including freeze-thaw <br />testing, on representative samples of the mixed and blended soil liner <br />fill. Geotechnical testing of amended soil liner that has been carefully <br />mixed and blended in the laboratory will not be acceptable. CCVG should <br />also investigate the potential for permeability and density effects on <br />amended soil liner fill following a saturation/desiccation cycle. <br />3. CCVG must conduct interfacial shear strength testing for the amended <br />soil liner fill and the geomembrane, as well as triaxial shear strength <br />testing for the amended soil liner fill, and demonstrate that no adverse <br />stability effects will be caused by the bentonite amendment. <br />cc: Jim Pendleton <br />Jim Stevens <br />Jim Dillie <br />Bruce Humphries <br />C:\WP51\CRESSON.57 <br />