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0 <br />Mr. Zach Trujillo <br />November 20, 2015 <br />Page 10 <br />ITEM 76. In Volume 15, Rule 2, Page 22, the text refers to well DH -76-8 in the description of water <br />levels in the Trout Creek Sandstone. Please draw well DH -76-8 on Map 1013. <br />Response: A response for this comment will be submitted at a later date under a separate cover letter. <br />ITEM 77. The text in Volume 15, Rule 2, Page 22, also describes potentiometric head values at several <br />points in the Trout Creek Sandstone. It is not clear from the material that has been submitted how well <br />characterized the potentiometric surface in the Trout Creek Sandstone is in the vicinity of the proposed <br />Collom pit. Such characterization of the baseline conditions will allow an assessment of the veracity of <br />the Probable Hydrologic Consequences (PHC) later in the life of the permitted operation. Please project <br />the baseline potentiometric surface in the Trout Creek Sandstone over the Colowyo permit area, including <br />the proposed Collom expansion, onto a map (possibly Map 1013). The map should identify the points that <br />were used in the projection. Depending on seasonal variability, it may be appropriate to show a maximum <br />and minimum projected surface. If CCC has already addressed this characterization through previous <br />mapping or modeling work, please direct DRMS to the appropriate documentation. <br />Response: A response for this comment will be submitted at a later date under a separate cover letter. <br />ITEM 78. Table 2.05.6-4 gives an inventory of springs and seeps near the proposed Collom permit <br />expansion area. Since PR -4 changes the nature of the proposed expansion, some of the information in the <br />table is no longer precisely relevant. Please review Table 2.05.6-4 and update the information in column <br />3 (Direction from Proposed Pit) to incorporate the changes to the proposed Collom pit. <br />Response: Table 2.05.6-4 has been updated to reflect the direction of the Collom Pit. It has also been <br />updated with ownership and use information in accordance with Rule 2.04.7(j) (N). <br />ITEM 79. Figures 2.05.6-1 and -2 show a plan and cross-sectional view of the proposed Collom pit, with <br />dewatering wells and their cones of influence projected. Since PR -4 changes the details of the proposed <br />pit, some of the information shown may no longer be accurate. Please review Figures 2.05.6-1 and -2 and <br />verify that the information shown accurately reflects the plan proposed by PR -4. (Refer also to items 65, <br />66, and 67 in this letter.) Please also update the permit boundary layer drawn on this figure. <br />Response: A response for this comment will be submitted at a later date under a separate cover letter. <br />ITEM 80. CCC has made the case that the Trout Creek Sandstone is hydrologically isolated from the <br />potential effects of mining, owing to vertical separation and the presence of the K,,, confining layer. The <br />Division concurs that, given those conditions, the probable hydrologic consequence of the activity <br />proposed in PR -4 on the Trout Creek Sandstone is that it will not be impacted; however it will be <br />necessary to verify this prediction before final bond release. CCC has not proposed a monitoring point or <br />points that would allow such a verification to be made. <br />a. Please elaborate on the vertical separation of the Trout Creek Sandstone, and the thickness and lateral <br />continuity of the Km layer in the text (refer also to Item 68 in this letter). The discussion should <br />include the impacts of the faults mentioned in item 10 of this letter on the integrity of the confining <br />layer. <br />b. Please provide references in the text to supporting data. <br />AN EQUAL OPPORTUNITY/AFFIRMATIVE ACTION EMPLOYER <br />A Touchstone Energy'Cooperative t <br />