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![ E M O R A N D U M Date: October 7, 1994 Our Ref.:943-2732 TO: John Hardaway, Cripple Creek and Victor Mining FROM: Terry Mandziak, Golder Associates Inc. ~l/I RE: DRAIN COVER FILL Golder Associates inc. (Golder) has recently obtained eight Quality Control (QC) samples taken from Pad No. 2 that is to be the source of the Drain Cover Fill. The eight QC samples (Sample No.'s 5-02 through 5-09) were taken from various locations on Pad No. 2. Table 1 summarizes the results for the grain size distribution analyses performed, With the exception of one sample (Sample No. 5-02), all samples met the gradation requirements for the Pond Drain Cover Fill; only 2 samples met the specifications for the Pad Drain Cover Fill. Table 2 summarizes the "maximum and minimum percent finer" than for the eight QC samples. Table 3 presents the "average percent finer than" for the eight QC samples for each sieve, as well as percent finer than for +1 standard deviation and -1 standard deviation. Each Table shows that the Pad No. 2 material will meet the Pond Drain Cover Fill specification, but will have difficulty meeting the specification for the Pad Drain Cover Fill. Jim Pendleton with the Division of Minerals and Geology (DMG) has expressed concern regarding the geomembrane puncture potential with the proposed change in specifications. On August 31, 1994, David Kidd of Golder performed puncture testing on 2" stones in the Soil Liner Fill. Drain Cover Fill was placed directly on an 80 mil smooth VLDPE geomembrane, underlain by Soil Liner Fill (ironclad tailings). The composite layer was then subjected to a static load of 300 psi (approximately 375 feet of equivalent ore) overnight. Soil Liner Fill was taken from the Heap Leach Pad area, and contained some gravel between 3/4 inch and 2 inch in size at the surface of the fill. The Drain Cover Fill was obtained directly from Pad No. 2, with material less than 1 inch and was generally well graded to the sand fraction. Upon completion of the testing, the VLDPE was cleaned and inspected. No perforations were visible when the VLDPE was examined over a light source. Vacuum testing was performed on the specimen and no pinholes were observed. The puncture testing performed on the VLDPE of the 2" stones should represent the conditions expected. The QC samples taken from Pad No. 2 are generally 1 inch minus, with only 1 to 3 percent being retained on the 1 inch sieve. The cross-section of material tested is characteristic of the area above the pond, having Soil liner Fill overlain with 80 mil smooth VLDPE geomembrane overlain with Drain Cover Fill.