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9/30/93 <br />Responses to Comments <br />San Luis Reclamation Evaluation Report <br />Page 11 <br />REBPONSEB TO CON1iENT8 <br />SAN LDIB RECLAMATION BVALIIATION <br />Comments From Dr. Jim Pendleton <br />Comment: <br />BMRI expressed a strenuous concern regarding the possibility of <br />puncturing the liner during the attempt to sample the tailings. <br />The Division agreed with their concern. BMRI intended to limit <br />any borings to no closer than five feet to the liner. In <br />addition, BMRI samples the tailings using hand augering <br />equipment to avoid the possibility of a mechanical drilling <br />mishap damaging the Iiner. The Division agreed with ill these <br />concerns. However, the hand augering equipment chosen by BMRI <br />has serious limitations in that it could not retrieve samples <br />of saturated material. As a result the tailings samples were <br />constrained to unsaturated material with little of the <br />potentially interactive pore fluids. It appears this equipment <br />constraint inappropriately limited BMRI's sampling and <br />characterization of the tailings. <br />Response: As discussed in Section 1.0 of the Preamble to these <br />comment responses, BMRI attempted to retrieve <br />samples using the hand augering equipment in order <br />to expedite the sampling program and miniriize the <br />pre-sampling construction required to compleJte ramps <br />for heavier sampling equipment. Once BMRI eNaluated <br />the samples obtained, it was believed that the <br />various detoxification procedures used at the <br />facility were adequately represented in the tailings <br />samples obtained (see Table 1). <br />As discussed throughout the report and in Section 3 <br />of the Preamble, when BMRI attempted tq obtain <br />samples of the pore water, even in saturated <br />portions of the tailings, the compacted implermeable <br />nature of the deposited tailings made collection of <br />an adequate sample difficult, if not impossible. <br />In short, the functioning of the thip layer <br />deposition acts to provide the desired cond'tion of <br />dewatered, low permeability tailings which makes in- <br />situ fluid sample collection impossible. This same <br />system will act to prevent the long teitm water <br />movement and mobilization of entrained pore water <br />impossible. Permeabilities such those measured in <br />the deposited tailings during the geotechnical <br />