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_, <br />1 ~ 1~ <br />~~ t..~ <br />Letter to Anne Beierle -2- Mav 30, 1996 <br />of the acid generating potential of the waste. While the Division agrees <br />that X-ray diffraction data may be useful, the types of interference <br />associated with the X-ray diffraction may prevent identification of <br />mineral species that can have a profound effect on acid generation <br />potential, even when these species comprise only a small percentage of the <br />whole rock. Since there is no direct way to interpret either the ANP:AGP <br />ratio method or the difference method for comparing acid production <br />potential with acid neutralizing potential, the Division's practice is <br />that materials with ANP:AGP ratios less than 3:1 will be assumed to be <br />acid generating, and would be subject to special handling to protect the <br />material from the effects of weathering. However, the Division agrees <br />that the acid-base accounting results should not be interpreted in <br />isolation, but rather should be integrated with other geological and <br />geochemical information for interpretation. O <br />3. It is stated in the work plan that if the total sulfur content of a <br />sample is found to exceed 0.16 percent, that the sample would then be <br />analyzed for sulfur form. The Division assumes that the analysis for <br />sulfur forms would be undertaken so that sulfate sulfur and residual <br />sulfur could be excluded from the acid-base account. Please be advised <br />that it is the Division's position that, since laboratory digestions used <br />to measure sulfide sulfur tend to result in an underestimate of sulfide <br />sulfur, total sulfur determined by Leco Furnace is an acceptable and <br />conservative input to an acid-base accounting. The Division would also <br />accept a procedure by which both total sulfur and sulfate sulfur are <br />determined by Leco Furnace methods, and the difference (total minus <br />sulfate) is input to the acid-base account. Dtl.e.- ~~,~,K ~~~„ <br />4. Please note that I have not commented on the regulatory aspects of <br />the Henderson Mine fill which were targeted in your letter dated May 14, <br />1996. Rather, I have confined the scope of this letter to the work plan <br />memorandum prepared by yourself and Craig Ford dated May 6, 1996. The <br />regulatory aspects of the fill will be addressed separately. <br />Please provide an addendum to the Henderson fill acid drainage work plan <br />that addresses the enumerated issues (1, 2, and 3) in this letter. <br />If you have any questions, please contact me. <br />Sincerely, <br />Allen C. Sorenson <br />Reclamation Specialist <br />~~. ~.~~~ <br />C:\WP51\HENDEPP4.TR <br />i 1 `~` r/ <br />1 l~ .. <br />Y' <br />