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• <br />The following section explains part of the problem of determining the source and percentages of fluids <br />in the leak collection system. A three-fluid mixture and atwo-fluid mixture are considered. <br />THREE-COMPONENT MIXTURE <br />The equation to calculate the propoRions of each fluid in a simple mixture cannot be solved uniquely. <br />All that can be said for this case is that the upper and lower pH and cyanide measurements represent <br />upper and lower bounds of the mixture. <br />TWO-COMPONENT MIXTURE <br />A two-fluid case can be solved uniquely if it is assumed that nothing happens, chemically, to the <br />mixture that would remove or add acid or cyanide from or to the mixture. This assumptio may be <br />reasonable for pH, but not for cyanide; CN would be stable in a process solution above pH 9.5, but <br />would transform to HCN and tend to volatalize at lower pH values. So, for sake of a calculation, I <br />have assumed the following: <br />a. the mixture is composed of process solution and meteoric water <br />b. cyanide has not volatilized from the mixture (not a good assumption) <br />c. acid was neither consumed nor generated due to mixing (a fair assumption for mixtures <br />in solution for this short duration, but still not a perfect assumption). <br />A solution with 10 ppm cyanide, as in the LCS, could be produced from 1 part process solution and <br />20 parts meteoric water. However, to produce a solution pH of 7.5 would require 50 parts process <br />solution and 1 part rainwater. <br />Process Ratio <br />Solution Meteoric water :Process solution <br />CN = 10 20 : 1 <br />pH = 7.5 1:50 <br />From this it should be evident that simple mixing of meteoric water and process solution cannot <br />produce the results observed. (The pH scale, a log scale, produces mixes whose results are dominated <br />by the lower pH value.) Obviously the above assumptions cannot apply to this case. Either pH or <br />CN does not behave conservatively. <br />A simple solution to the problem could be that cyanide in the process solution breaks down in the <br />lower pH meteoric or other water. <br />Unless the compositions of the three potential fluids can be measured specifically and more accurately, <br />there is not much that can be done with respect to geochemical modeling to tell where the fluids have <br />come from. Perhaps the best that can be done at this point is to assume that all of the material in the <br />leak collection system was derived from above the liner, not below, and conduct whatever pump tests <br />are necessary to determine the leakage. <br />With this incredible rate of cyanide destruction, high quantities of cyanide are probably being added <br />to the makeup water. Previous calculations about cyanide application rates based on pounds of cyanide <br />