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,. ,'. ,,. 17 {j ' . ;Please clarify which sulfide sulfur value is the correct percentage of total sulfur. Please y ;.: ;;indicate how the ti7% {or 69%) value was derived. Responses '1'ltC,cotrect value is 67%. The 69~to was typed in error. The 67% was used in all of the assessme»ts. This correction is reflected in the replacement pages for Section 4.0 of Appendix 1 in Volume II, included as Attachmem 10 of this submittal, A replacement for Appendix A of Appenduc 1 in Volume ll of the Amendment Na, 8 application is also included in Attachment !0. The replaced pages reflect corrections to mathematical emus which were discovered prtor to receipt of these comments. Note that Attachtperit 10 does not attempt to revise conclusions or address the comments in the letter from the ONILR=dated June 14, ?A00. Those comments are addressed in this response document. ,. ~~... The ratio of sulfide sulfur to total sulfur was calculated by determining the ratio of the nitric acid exV3ctable sulfur to total sulfur far each sample fos which Sobek sulfur fractionation data ware available. The average of these ratio values was 679b. Residual sulfur was not assumed to be pyrite for the purpose of this calculation, However, sirxe the average residual sultLr level was only 0,04~yo compared to an average total sulfur value of 0.95%, the exclusion of residual sulfur was not expected to have:a large influence on the ratio. For example, the average of the ratio non-sulfate sulfur to total sulfur vvas 68'l0. '; . 3. Page 21-26, ;:The Reticulated Comparisons between blast-hole NNP, humidity relC and static rerr NNP results <are eottf tsing and in cases are not accurately reflected in the accompanying diagrams. Ir appears that the 3& humidity cell rests are interpreted ro represent the AGP & ANA data provided by the more than /00,000 samples from the currently mined area, but as the average ` ?NNP's of the two data sets dlfj`er, this presumpt(on seems questionable. It is presumed for ,, • ~ ..purposes of this comment that blast hate test results would provide more representative zinjotmation an C:5 ratios ojthe mined interval. The discussion in the top paragraph of page 2S ~' rydces littde to clarify the explanations. ~,~ Response: Huisiidity cell data provide only a part of the information that is available for CC&V to predict ARD risk. It-is important to note that we did not base our eruire prediction of ARD risk oa the humidity ceU tests.:rAdditionally, the humidity ceU samples were selected to ensure drat measurable sulfides were present in trout samples tested Therefore, the data set is biased towazds samples that have alower- thea-average NNP than what is commonly observed at CCr& V, It was the intention to use hutmdiry cell data:only to identify a reasonable criterion that would indicate what NNP level constitutes an ARA risk at CCTV. Figures 4.Za and 4.2b were meant to illustrate that samples with NNP values below zero had a risk of becoming acidic after weathering, and that samples with NNP values above zero generally would trot became acidic. The reason that fewer sample points are plotted in Figure 4.2b is because the data were not available far ANP and AGP values, although the NNP values were available. Consequently, the ANP/AGP ratio could not be calculated. for these satttpies. t:- Additioi<ially, the humidity cell data were used Drily to develop the ARD risk criterion for the CC&V site: In ader to predict ARD risk of overburden materials, the mnre extensive smtic tart databases wear used..Tlte coordinated use of humidity cell and static tit data is described in more detail in subsequent respotis~s: ~t,,; `. {a) The discussion on page 23 (3'r paragraph) refers mostly to Figures 42a and 4-Zb and ;e indicates that, based on the final pli of the humidity cell tests, "the AGOSA can be ` ~~ expected to generate circum-neutral leachates. " The text indicates that the "average ,:,