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<br />Lower TailinPs Pond. The cyanide concentrations in the lower tailings pond samples are <br />questionable at best. WAD cyanide was greater than total cyanide concentrations in both <br />filtered and unfiltered samples. In addition, filtered samples had higher concentrations than <br />unfiltered samples, especially for total ryanide (410 µgA in the filtered sample and only 180 <br />µg/1 in the unfiltered sample) (Table 3). Core Laboratories noticed after the holding time <br />had expired that the results for these samples were unacceptable. Core performed a <br />recheck on the samples, except for WAD ryanide in the unfiltered sample because <br />insufficient sample volume remained, and the results are presented in Table 3 (see Appendix <br />E). Al] recheck results are lower than original concentrations and cannot be considered <br />reliable because the holding times were exceeded. The most likely explanation for the <br />unacceptable results is the presence of a negative interferant in the unfiltered samples. This <br />would result in higher concentrations in the filtered samples than in the unfiltered samples. <br />There was much more particulate matter in the lower tailings pond than in the upper tailings <br />pond on the day of sampling. It is possible that the potential negative interferant is <br />interfering more with the total ryanide analysis than the WAD cyanide analysis, but more <br />analytical work must be performed in order to establish the cause of the cyanide problem. <br />Concentrations of nitrate+nitrite, copper and sodium are within 10%(RPD) in both filtered <br />and unfiltered samples. Total concentrations are greater than dissolved for calcium, iron and <br />zinc. This indicates that colloidal calcium (likely as gypsum), iron (as iron oxyhydroxide) and <br />zinc may be present in the lower tailings pond. The presence of noticeable particulate <br />matter in the lower tailings pond may explain the differences between total and dissolved <br />concentrations for these constituents and may also explain some of the analytical problems <br />with cyanide in these samples. <br />Collection Pond. The collection pond again had the highest measured cyanide <br />concentrations. Cyanide concentrations at this location were higher than those measured <br />for the March sampling but considerably lower than those measured for the November <br />sampling. All total concentrations were higher than dissolved concentrations. WAD cyanide <br />concentrations were lower than total cyanide. The metals concentrations in the unfiltered <br />samples were all > 10%(RPD) higher than those in the filtered samples, indicating that there <br />may be colloidal calcium, copper, iron, sodium and zinc in the unfiltered samples. Total <br />copper concentrations were nearly five times greater than dissolved concefitrations, and <br />calcium and sodium total concentrations were both ]6%(RPD) greater than dissolved <br />concentrations. These metals were determined because they can form complexes with <br />cyanide. However, if the metals are present as colloidal precipitates, they are not likely to <br />form solution complexes with cyanide. It is possible, however, that they could cause <br />interferences with the cyanide determinations in unfiltered samples. <br />RCG/Hagler, Badly, Inc. <br />