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• <br />Question: Given the uncertainties surrounding the chemistry of this <br />unique tailings mix, is there a worst case scenario in which i creased <br />discharge of heavy metals and/or cyanides could be projected? <br />The heavy metals in the deposited tails, from accessory minerals irl the ore <br />body, from metals added with the CYTOX reagents, from thel copper <br />catalyst needed in the INCO process, and from soluble metals precipitated <br />in the processing of the tailings ponds represent a potential sipurce of <br />future problems if [hey are leached to ground or surface waters. <br />Simple or complexed cyanides in the standing water or pore Ovate as well <br />as complexed cyanides deposited in the tailing solids could sim lady be <br />discharged to the environment under future worst case conditions. <br />We simply do not know enough of the potential for long term m'crobial- <br />induced reactions in the tailings deposit, of the possible complex.Feaction <br />chemistry of cycling aerobic and anaerobic reaction condition, of the <br />impact of varying water quality percolating into the deposit over ~ ears of <br />time, or of possible changes in reactivity of groundwater ente ing the <br />deposited tailings to say with certainty that some combination o factors <br />will not release the metals and cyanide to the environment at ,evels of <br />concern or danger. <br />While I do not see any information in the documents I have reviewed which ignals a major <br />risk of hazardous discharges from the tailings in the short or long term, ther~is simply nut <br />enough sound chemical or anecdotal operating experience data from similar installations to <br />tell me that such risks are insignificant. In this situation, and with a litany of cases which <br />might be cited to underscore the unexpected problems which have arisen wh n buried <br />wastes were assumed to present no problems, it would appear prudent to pr pose that the <br />current situation is not accurately represented by the data used to develop tl a original <br />permit and to set the initial reclamation bond but, rather, that the modified ailings and <br />operations at the facility should be responded to with a modified permit and bond <br />documents. <br />I would recommend that revisions in these items reflect: <br />I. A requirement that longer monitoring with <br />safe conditions and detect problems early b <br />should include samples from any standing <br />from peripheral groudwater monitoring <br />groundwater wells or surface waters enter <br />comprehensive and maximally protective. <br />DEH06 ] 693 <br />complete analyses tqq update <br />e included. This monitoring <br />waters in the ponds,~samples <br />wells, and sampl s from <br />ing the tailings are w be <br />a <br />