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~ ~ <br />S~z1Air tdlling5 treatment prOCeS> deiCriC2d 1n TR-O10 as d flndl pr CeSS tJ <br />achieve the cyanide levels specified in the permit. TR-010 was submitted to the <br />Division on June 16, 1992 and is currently under review. <br />6. BMRI has made a good faith effort to reduce cyanide levels'•in the ponds, <br />and by using the hydrogen peroxide process, has achieved a substantifil reduction in <br />such levels in the tailings ponds. By continuing to operate the plaht, and <br />continuing to treat the solution using the hydrogen peroxide method, the Division <br />believes that BMRI should be able to continue to reduce the WAD cyanide level to <br />less than 15 ppm in the active lower pond and to less than 10 ppm in~the inactive <br />upper pond. Implementation of the INCO S02/Air tailings treatment p ocess by <br />BMRI, scheduled for early October of 1992, is intended to bring the ~yanide levels <br />within both tailings ponds into compliance with the permit standardsiof 4.4 ppm <br />total cyanide and 3.8 ppm WAD cyanide. <br />7. There is no evidence that the elevated cyanide levels have~in any way <br />impacted surface or ground water in the vicinity of the site. There ore, BMRI was <br />not required to cease using cyanide so long as it meets the standard prescribed by <br />the Board. Therefore, as described in the May Order, it is necessar to enhance <br />ground water monitoring at the site. It is unlikely that any impact to ground <br />water will pose a hazard to the health and welfare of the public pri r to the <br />installation of additional necessary ground water monitoring wells. <br />ORDER <br />Based on the foregoing, the Board hereby enters the following additional corrective <br />action order: <br />tl) BMRI has implemented their Hydrogen Peroxide Tailings Treatment, as described <br />in their TR-007 application, in their active lower tailings pond, since June <br />15, 1992. BMRI has reduced the WAD (weak acid dissociable) cyanide <br />concentrations in the active lower tailings pond from aporoximat ly 80 ppm on <br />June 15, 1992, to 12 ppm as of July 9, 1992. BMRI has determine that `he <br />Hydrogen Peroxide Tailings Treatment is capable of reducing the AD cyanide <br />level in an active tailings pond to approximately 15 ppm. <br />Prior to July 16, 1992, BMRI had not directly applied the Hydrog~n Peroxide <br />Tailings Treatment to the then inactive upper tailings pond, whi h was reported <br />by BMRI to have a WAD cyanide level of 39.6 ppm on July 7, 1992.; After several <br />daily applications of hydrogen peroxide to the inactive upper pod, BMRI's <br />on-site analysis determined the WAD cyanide level within the ina tive pond to <br />be less than 10 ppm on July 20, 1992. BMRI concludes that the H~drogen <br />Peroxide Tailings Treatment is capable of reducing the WAD cyani a level in an <br />inactive tailings pond to 10 ppm or less. <br />BMRI shall continue to add hydrogen peroxide directly to both tailings ponds' <br />liquid pools, at appropriate rates, in order to achieve and main ain a WAD <br />cyanide level of 15 ppm or less in active tailings ponds and 10 pm or less in <br />inactive tailings ponds. <br />WAD cyanide levels shall be determined in accordance with APHA/AIWA Standard <br />Methods, 17th edition, 1989, 4500-CN, 14ethod I, pages 4 - 38. <br />-~- <br />