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On October 21, 1992, the INCO SOZ/Air cyanide detoxification circuit was started-up under <br />manual controls. The use of Cytox and hydrogen peroxide continued during the operational <br />adjustment period of the INCO circuit. On November 6, 1992, the hydrogen peroxide treatment <br />was transferred from the lower pond to the collection pond. By November 15, 11992, the INCO <br />circuit was fully operational and tailings deposition was switched from the lotver pond to the <br />upper pond; the use of Cytox was discontinued. At the time the INCO circuit }vas brought on- <br />line the maximum beach elevation of the lower pond was 8,562, and the rjtaximum beach <br />elevation of the upper pond was 8,561. <br />2.2 Field Investi ag tion <br />2.2.1 Collection of Tailin sg Samples <br />A total of thirteen locations were sampled for tailings material. Six locations Mere sampled on <br />the upper pond beach and seven locations were sampled on the lower pond beach. The safety <br />• of sampling personnel and accessibility to the beach played major roles in the ~ampling timing <br />and sampling locations. <br />2.2.1.1 Sample Timing <br />Tailings were deposited in the lower pond from February through mid-Novembek, 1992. Thus, <br />the beach area was not accessible for sampling during this period. Tailings heated with the <br />AVR system, interim detoxification methods and the initial INCO system deposition were <br />deposited in the lower pond. <br />On November 15, 1992, deposition was switched from the lower impoundment to the upper <br />impoundment. Sampling of the upper pond beach took place from November l0 through 13, <br />just prior to the deposition switch-over. Holes 1 through 6 are located ion the upper <br />impoundment pond beach azea. <br />• <br /> <br />