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T <br />Mr. Zach Trujillo <br />November 20, 2015 <br />Page 8 <br />ITEM 68. In Volume 15, Rule 2, Page 13 the text reads "The Trout Creek sandstone underlies the lowest <br />surface recoverable seam to be mined at South Taylor (the 6789 seams) by approximately 590 feet". <br />Please revise this section of text to refer to the separation between the Trout Creek sandstone and the <br />lowest seam to be mined in the vicinity of the proposed Collom pit and use this value consistently <br />throughout the text of volume 15. Please also cite the data that allows CCC to accurately assess the <br />separation over this area. (Refer also to item 80 in this letter.) <br />Response: A response for this comment will be submitted at a later date under a separate cover letter. <br />ITEM 69. In Volume 15, Rule 2, Page 16 a paragraph appears to have been inserted that is not relevant to <br />the Collom area: "Overburden and interburden samples from drill holes 97-06, 97-09 ...... For clarity, <br />please remove irrelevant text. <br />Response: The paragraph noted in the comment has been removed. <br />ITEM 70. Of the six drill holes that were sampled for overburden/interburden analysis, only one falls <br />within the 1.4 square mile (approximate) footprint of the newly proposed Collom pit (C-04-25). The <br />guidelines call for a minimum of three sampling locations with a spacing of approximately one hole per <br />square mile (from reference 1 below). In the geochemical analysis, CCC has also cited a guideline <br />published by the Wyoming Department of Environmental Quality (from reference 2 below), which calls <br />for an initial sample spacing of one hole per 80 acres (which is equivalent to eight holes per square mile). <br />The geochemical data from the six holes is presented in Exhibit 6, Item 9, and summarized in table <br />2.04.6-7 and in the text. The data shows that hole C-04-25 contains a greater proportion of unsuitable <br />overburden material than the other five holes. For example: <br />• A significant proportion of the overburden sampled at this point (27%) contains Molybdenum at <br />greater than 1 ppm. <br />• The deeper horizons are notably high in Arsenic, with a maximum value of 39.8 ppm (compared <br />to the WY DEQ criteria of <2.0 ppm). <br />• The deeper horizons also have elevated levels of Sodium, as indicated by the high SAR values. <br />In summary, the data provided are not sufficient to adequately characterize the material that will be <br />disturbed by the proposed Collom pit. The analysis, as currently presented, underestimates the proportion <br />of material that fails to meet the suitability criteria. <br />a. Please revise table 2.04.6-5 to better reflect the content of the Wyoming DEQ reference cited. <br />b. Please present additional data that will allow more adequate characterization of the overburden <br />material in the Collom pit; pursuant to rule 2.04.6(2)(b)(ii) the Division suggests an initial spacing of <br />one hole per 80 acres. <br />c. Please revise Exhibit 6, Item 9; Tables 2.04.6-6 and -7; and the text of Volume 15, Rule 2, Pages 15- <br />18 accordingly. <br />d. In the process of addressing items b. and c., please be specific about which horizons will be handled <br />selectively and how that will be accomplished. <br />Response: A response for this comment will be submitted at a later date under a separate cover letter. <br />AN EQUAL OPPORTUNITY/ AFFIRMATIVE ACTION EMPLOYER <br />A Touchstone Energy'Cooperative <br />r-- <br />