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9/30/93 Responses to Comments San Luis Reclamation Evaluation Report Page 4 2.1 Upper Disposal Area Samplin The Upper Disposal Area was sampled first in mid Nove~pber. No tailings deposition had occurred in the Upper Disposal Area during the time that CYTOX or INCO had been used. ']The Upper Disposal Area free water pond was treated with hydrogen peroxide to detoxify cyanide in the pond, however hydrogen peroxide generally has no effect on solids and no tailings deposited in the Upper Area were treated with hydrogen peroxide. In addition, Figure 2.2 shows that the sampling occurred well outside of the approximate limits of the hydrogen peroxide treated water pool. No influence should be ccurring on the tailings beach from the hydrogen peroxide ad~ition in the pond. Therefore, samples from the Upper Disposal Area are representative of only AVR treated tailings. All samples were within between 3 and 7 feet of the tailings liner and xtepresent the entire column of tailings in the Upper Disposal Area. 2.2 Lower Disposal Area Sampling Once sampling of the Upper Disposal Area had been cgmpleted, deposition of tailings was switched from the Lower Disposal Area to the Upper Disposal Area and the tailings in the Lower area were allowed to dry. Sampling of the Lower Disposal Area occurred in mid December. Although the tailings had not completely dried, surface freezing allowed access to the tailings sooner than expected. Concerns were expressed by several readers that the holes in the Lower Area do not represent the entire detoxification column. The holes which were sampled in the lower area do represent the entire column. Hole 8 went approximately 15 inches into the AVR deposited tailings, Hole ~I12 went approximately 22 inches into the AVR tailings, and Hole X13 went approximately 24 inches into the A~7R tailings. These samples should provide a good indication of the effect of both SOS treatment and CYTOX on the AVR treated tailings. As previously discussed, the upper area tailings sample's should provide a good indication of the behavior of the AVR tailings alone. Here again only the standing water pools in both disposal areas were treated with hydrogen peroxide and the samples were obtained from locations beyond the limit of influence. BMRI believes that the samples adequately represent the full range of treatments to which the tailings were subjected.