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9/30/93 <br />Responses to Comments <br />San Luis Reclamation Evaluation Report <br />Page 14 <br />entirety of the tailings in place. In fact, the pre- <br />violation, AVR-treated tails have gone largely un~sampled. <br />In addition, the shallow samples which were obtained in <br />both ponds may have been exposed to hydrogen ;peroxide <br />treated fluids prior to their collection and analysis. <br />Both PAES end Dr. Posey have expressed similar concerns <br />regarding whether BMRI adequately or represenltatively <br />sampled the tails. <br />I do not believe that this necessarily invalidates any of <br />the work completed so far. However, at a minimum, BMRI <br />wi1Z have to complete sampling of the appropriate tailings <br />materials. Obviously, a different sample co~Ilection <br />method and/or apparatus will have to be used. In my <br />opinion, at least two holes should be completed in each of <br />the tailings ponds. These holes should sample the entire <br />tailings section to five feet above the liner. This <br />should also provide opportunity to collect adequate in- <br />situ fluid samples to define the character and <br />distribution of tailings fluid throughout the Mailings. <br />Finally, BMRI should evaluate the relationship if the <br />three-dimensional tailings constituency to the samples <br />which have previously undergone extensive labboratory <br />analysis. If the supplemental sampling determines that <br />the materials previously exhaustively analyzed were <br />representative of the tailings mass then no additional <br />laboratory analysis would be necessary. If not, <br />additional analysis will need to be completed. I do not <br />believe this determination can be completed at this time. <br />BMRI is simultaneously seeking approval to commence <br />construction of its first of two proposed up-valley <br />tailings embankment raises. In anticipation of this <br />construction, tailings deposition will be occurring in the <br />Upper Pond. BMRI will mobilize an earthwork contractor to <br />construct the raise in multiple lifts. This will provide <br />an opportunity and the equipment with which to facilitate <br />the sampling of the Lower Pond. If necessary, a temporary <br />pad of earthen material could be temporarily placed on top <br />of the beach tailings. A small hollow stem agger rig <br />could then be employed to recover a complete profile of <br />tailings with appropriate in-situ fluid samples for <br />comparative analysis. <br />Response: As discussed in the previous response, the tailings <br />sampled in the upper disposal area represent AVR <br />tailings and were collected to within three to seven <br />