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9/30/93 <br />Responses to Comments <br />San Luis Reclamation Evaluation Report <br />Page 13 <br />peroxide since hydrogen peroxide was added only to <br />the free water pool and was not used to treat <br />tailings solids. BMRI believes that upper pond <br />samples are representative of only AVR treated <br />tailings and have not been influenced by the <br />hydrogen peroxide addition in the pond. See Figure <br />2.2 of the Reclamation Evaluation Report for the <br />location of the free water pool relative to the <br />sample locations. <br />Comment: <br />In contrast, the Lower Tailings Pond has commenced its <br />operational life identically to the Upper Pond, receiving <br />pre-violation, AVR-treated tails from April of 1991 <br />through April of 1992. Following the NOV issuanice, BMRI <br />commenced CYTOX treatment of the tails entering tihe Lower <br />Pond on April 7, 1992, at which time the tailings beach <br />had reached an elevation of approximately 8551' amsl. On <br />June I5, 1992, BMRI commenced hydrogen peroxide treatment <br />of the standing fluid pool in the Lower Pond, while <br />continuing tails treatment with CYTOX. On June 15, 1992 <br />the Lower Pond tailings beach had reached an elevation of <br />approximately 8555' amsl. The addition of CYTOX was <br />discontinued through October of 1992. On November 6, 1992 <br />the INCO Air/SO2 reactor became operational, at which time <br />the tailings beach had reached an elevation of <br />approximately 8562' amsl. BMRI completed auger sampling <br />of the Lower Tailings Pond at seven (Holes ,~7 - #13) <br />locations on December 16th through 19th, 1992. During <br />March of 1993, at the suggestion of the Division, BMRI <br />subsequently drove an additional hole (~8.5) and collected <br />one in-situ fluid sample for analysis. <br />In reviewing the text, figures and "Tailings Samlple Hole <br />Logs" contained within the report, I am concerhed that <br />BMRI sampling of the pre-violation tailings was lilmited to <br />shallow hydrogen peroxide exposed tails in the UpE}er Pond. <br />Only hole ~8 may have penetrated the uppermost foot of AVR <br />treated tails in the Lower Pond, and these tails may also <br />have been penetrated by hydrogen peroxide treated fluids <br />subsequent to deposition and prior to sampling. Further, <br />only hole #7 appears to have penetrated the CYTOX bearing <br />tails in the Lower Pond. All the other holes, and the <br />samples obtained from them, appear to be limited to the <br />tailings deposited during the application of hydrogen <br />peroxide to the Lower Pond. As a result I am croncerned <br />that the sampling performed does not represent the <br />