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<br />The question arose as to whether the humidity cell samples had been rinsed prior to initiation <br />of testing. The standard procedure for dynamic acid-base accounting testing is to use minus ''/c- <br />inch rock which is first saturated with distilled water ("DI;" pH = 5.5), then aerated with dry, <br />filtered air, followed by humid air, Flooding with DI water at pH=5.4, and draining for <br />sampling and chemical analysis. Samples are not inoculated with bacteria because bacterial <br />action, should it develop, should be the result of the ambient bacteria that may be dormant which <br />are allowed to activate naturally when and if the system goes acidic. If the rock contains a <br />sufficient quantity of an alkaline component, the system pH will remain above 3.0 and bio- <br />oxidation will not occur. (See Enclosure #10, Volume VIII, Amendment No. 6, "Metals <br />Mobility Test Protocols" McClelland Laboratories, February 24, 1994.) <br />Perhaps the most appropriate measure of whether spent ore will maintain its alkalinity and <br />remain essentially neutral in the environment after cyanide removal is answered by the analysis <br />of spent ore and spent ore solution for closed leach facilities in the District. For example, <br />CC&V has submitted a quantity of spent ore measurements in the past, as part either of the <br />application for Amendment No. 6 or as part of water contact tests for spent ore conducted to <br />support use of spent ore for road base and other construction. Samples represented (1) the <br />Carlton Mill Tailing (See Amendment No. 6, Volume VI), (2) Pad #1 (ibid), (3) Pad #2 (/bid), <br />(4) Pad #3 (e. g., June 8, 1995), (5) Pad #4 (e.g. March 19, 1996), and (6) Ponds 4C and 6 <br />water quality data (e.g., March 28, 1996, August 7, 1997). If all of the water quality data from <br />these tests of spent ore are assembled, we find the following statistics for pH: <br />Average: 8.17 (n=36) <br />Range: 6.90 - 10.51 <br />Standard Deviation: 1.51 <br />ISth and 85th Percentiles: 7.52 and 8.84. <br />These samples represented ore that was last leached at least 6 years ago and some that was last <br />leached at least 30 years ago. We know that lime was added to each facility during active <br />operations. As the minimum pH (6.90) shows, acidic conditions have not occurred and there <br />are no trends suggesting that such conditions will occur. In the few places where historic tailing <br />residuals still exist, there are no signs of acidic conditions. <br />3. The static Acid Base Accounting data for the two Cresson valley leach samples undergoing <br />humidity cell testing were provided to the OMLR in the form of the McClelland Laboratories <br />report sheets. In summary, the data presented were as follows: <br />ACID BASE ACCOUNTING FOR VLF SAMPLES: McClellaN Labonwncs ABA Smim AG, ANP, NNP Uons CaCOJ1000 sorts) <br />Samplc Pasw pH S, 5' S0, AGP ANP NNP Rmio <br />Cresson Plisse 1 - <br />mows I50 mesh ].]9 0.50 013 0 2] ] 1 10.3 +7 0 I e <br />Cresson Phlti II <br />minus 150 nosh B 11 Oq 0.10 O.IJ 6.3 I IA +5.1 LB <br />t~ <br />