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K E A P A C I F I C <br />present in true solution in a porefluid that contains no particulate matter. For example, iron <br />would be limited to a one or two parts per million, at the most, in the high pH environment <br />of the tailings porefluid, rather than the 96 ppm seen in one of the porefluid analyses, Isee <br />Table 21. <br />Analyses of Method 1312 Leachates <br />USEPA Method 1312, the synthetic precipitation leach procedure, was designed by the <br />USEPA to simulate the leaching of species from waste materials by 'natural' precipitation at <br />a pH value of pH 4.2. The data from leaching the five San Luis tailings samples using <br />Method 1312 are given in Table 3. <br />The data in Table 3 suggest the following: <br />• the tailings Leachates are relatively low TDS, alkaline solutions which carry <br />same low to moderate alkalinity; <br />• levels of major ions in the Leachates are low. It should be noted that the <br />leach solution contains sulphate from the sulphuric acid used to acidify the <br />solution and hence the sulphate number do not represent li,e. overestimate) <br />the sulphate that could be leached from the tailings; and <br />• very few values of any of the trace species determined for the Leachates are <br />above the detection limit of the analysis methods used. Only very low levels <br />of manganese and barium appear in the Leachates. <br />Overall, the San Luis tailings samples collected in September 1993 produoe very 'clean", <br />good quality Leachates when leached with synthetic rainwater, using the USEPA Method <br />1312 procedure. <br />Sincerely, <br />KEA PACIFIC HOLDINGS INC. <br /> <br />Adrian Smith <br />1007161 <br />