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9/30/93 Responses to Comments San Luis Reclamation Evaluation Report Page 5 However, since sampling of tailings at depth appeared to be an ongoing concern, BMRI collected additional samples at depth during the week of September 20th utilizing vibra core sampling techniques. Information on the vibra core drill is included as Attachment 1. Two holes were completed to a depth of 55 feet or within 10 to 15 feet of the liner. These two holes extended approximately 38 feet in to the AVR deposited tailings. Ten feet above the liner was set as the maximum depth based on the requirements of the geotechnical investigation that holes completed using mechanical drilling equipment not qo within ten feet of the liner. A third hole was completed to a depth of 25 feet where it met refusal due to the dense nature of the tailings material. The 25 foot depth extends approximately 7.5 feet into the ANR deposited tailings. Samples of tailings and pore water were submitted for analyses and the results will be presented upon completion of testing. 3.0 Pore Water Sampling As discussed throughout the report, when BMRI attempted to obtain samples of the pore water, even in saturated portions of the tailings, the compacted impermeable nature of the deposited tailings made collection of an adequate sample difficult, if not impossible. First, Bl~ti requested that CORE Laboratories attempt to obtain a water sample from each tailings sample submitted for testing, however after several attempts at using a vacuum system to pull water from samples, CORE indicated that inadequate water could be obtained for valid analysis and this was ceased. BMRI then attempted to collect a pore water sample using a BAT system type of down hole vacuum lysimeter in Hole X8.5. The sample was collected from approximately 20 feet in depth, or seven to eight feet into the AVR deposited tailings. The yield was approximately l0 milliliters per hour which made collection of an adequate sample for testing a long and difficult process, even in the so called saturated poYtion of the tailings. In addition, the length of time to collect a sample and the inability to preserve the sample until after it is pulled from the BAT system calls into the question the validity of the results, in particular the cyanide results, as discussed in the report. Although the results indi ate low levels of residual cyanide in the sample, BMRI's geo hemical expert, Dr. Adrian Smith, believes that any sample of t is type should be used with caution.