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<br />Review of Abatement ~8 Response <br />August 4, 1993 <br />Page 4 <br />APP G Some of the humidity cell test results look odd, although this <br />observation is certainly limited by my knowledge of tt~e mineralogy <br />of the ore body. <br />Cumulative Fe reports in micrograms whereas cumula ive sulfate <br />reports in milligrams, and the sulfate concentration are nearly <br />1000 times greater than the iron. Apparently, there i a source of <br />sulfate other than FeSl. Ae I am not aware of the presence of <br />sulfates such as anhydrite or gypsum in the ore body, I have assumed <br />that the sulfate which reports in the humidity cell t ste is from <br />weathering of sulfides. If this ie so, there are sulfides other <br />than Fe. I do not see the source in the other leacha a analyses. <br />What is the source of sulfate in the Humidity Cell Te~te7 <br />RESPONSE TO COMMENTS FROM PEOPLES ALTERNATIVE ENERGY SERVICES <br />The Division received comments and concerns from Peoples Altern tive Energy <br />Services August 2, 1993. The following comments, numbered accor,ing to PASS <br />comments, respond to their concerns. <br />EPA Method 1312 uses a considerably weaker acid when comared to the <br />prescribed extraction reagents used when performing the TC procedures <br />which we feel would have been more appropriate for the Zeac ate tests. <br />RESPONSE: The reagents that would be most appropriate and t e conditions <br />under which any teat should be run - in this or any other cal -are those <br />that would moat closely reflect the site conditions. Rain ater ie the <br />reagent that would moat closely reflect the site conditions i my opinion. <br />The TCLP test is likely to be more destructive than simulat d rainwater, <br />but I do not feel it would be appropriate to simulate lea hing of the <br />tailings with reagents that are not likely to occur at the site, nor in <br />quantities that are likely not to be present. While the r~eagenta used <br />wit he EPA Method 1312 are certainly weak compared with thoee~ used in the <br />TCLP, I believe the answer lies somewhere between the two teats. EPA <br />Method 1312 does not account for the effects of generation of sulfuric <br />acid, which will be produced in sulfide-bearing systems. (Se~ my comments <br />on this subject in the earlier sections). <br />P <br />site/depth for this particular set of information. <br />RESPONSE: I agree with the assessment. See my commen~e regarding <br />assumptions about depths of wells. <br />The relationship between samples run for leachate testing ~nd the data <br />resented are so nebulous that we cannot decipher what data g es with what <br />