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ADA TECHNOLO6IE:; IiIC. TEL.'.~~~3-~ _~_-`h,}~, ?~.~n 0_~ '?1 200° No .002 P.04 <br />• • <br />reasonable approach might be to be sure the correct tests are performed <br />to show peroxide WILL meet the 4 ppm cyanide specification with REAL <br />pond waters and solids and WITH CYI'OX reagents added <br />slmultaneoualy under a variety of conditions. With this data in head, the <br />confidence level will rise significantly. , <br />o Quantitatioa of the effectiveness of peroxide in getting to 4 ppm cyanide <br />levels in the ponds cannot rely on the color of the pond waters and a <br />regular suite of copper and total cyanide analyses are necessary. As <br />pointed out by your stag, these analyses need to [nclude enough samples <br />to be sure pond heterogeneity is acrnunted for. <br />o In all of the discussion and guesswork surrounding the quality of cyanide <br />analyses to date and the problems with sampling and analysis for this <br />toxic, there seems to be a tendency to move toward dealing only with WAD <br />cyanides or to lump target cyanide levels Into a RANGE of, for exatnple, 4 <br />to 40 ppm. <br />In this regard, I would hope and expect that the original target of 4 ppm <br />or less o[ total cyanide fn We tailings pond wilt remain the lssge with <br />respect to permit compliance. <br />o If the peroxide process is as effective as put forth by BMG, then one might <br />reasonably ask why the INCO process !s still expected to be used as yet a <br />third option to get rid of cyanides. <br />o The issues of cyanide analysis, control, end permitted levels are certainly <br />the main ones addressed in the proposed technical revision, bpt the <br />presence of copper in the tailings waters Is also of concern h~om a tgxicity <br />standpoint and, to date, I have not seen any discussion of risks iroln this <br />metal. <br />As the various cyanide control approaches are considered, the questions <br />o[ Impact of these on copper levels and potential for near term or future <br />teaching of copper into the surface or ground waters need to be addressed. <br />The inftlal permitting data did not address copper since it wa not <br />anticipated is the ore profiles but its presence (in signi>~cant <br />concentrations) is now verified and thus its control deserves attentiotl. <br />I appreciate the timely manner in which you and others in your office have transmitted <br />information and replies in this matter to my attention and I shall look forward tb seeing <br />you again at the upcoming public hearings on the San Luis project. <br />Sincerciy, <br />. -~ ~~~ <br />David >w Hyatt, Ph.D. <br />IA60992DEH1 <br />