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Chris Gilbreath Page 6 ITEM 77. This item has not yet been adequately addressed. CCC responded that Map 10B had been updated with the projected potentiometric surface of the Trout Creek Sandstone, and that the text had been inserted into Volume 15,Rule 2 to discuss the wells that were used to determine the surface. Contour lines at intervals of 100',from 6600' to 6800',were projected onto Map 10B.They indicate that the hydraulic gradient is such that groundwater would flow in in south-westerly direction. The text on proposed Page 23 indicates that 5 points were considered in the determination of this surface(C-05-33,DH-76-8,W-95-02,W-95-15 and UL-95-45). Of these, C-05-33 and DH-76-8 were rightly discarded since they were dry and uncased respectively. Several issues are evident: (1)W-95-15 is not shown on Map lOB; (2) There is potential confusion over the location of W-95-02, since another point(also in the Wilson Creek drainage)is labeled MW-95-02; (3) considering just UL-95-45 and W-95-02,since the location of W-95-15 isn't shown, the potentiometric gradient is in the direction of W-95-02, (based on the data summarized in the proposed text),which is approximately opposite to what has been drawn on Map 10B. Please address these issues and update Map 10B accordingly. ITEM 78. This item has not yet been adequately addressed. In the letter of November 20,2015, CCC stated that Table 2.05.6-4 had been revised,but a copy of the revised table was not found in the submitted material. ITEM 79. Response is adequate. ITEM 80. CCC has made the case that the Trout Creek Sandstone is hydrologically isolated from the potential effects of mining, owing to vertical separation and the presence of the K.confining layer. The Division concurs that, given those conditions,the probable hydrologic consequence of the activity proposed in PR- 4 on the Trout Creek Sandstone is that it will not be impacted; however it will be necessary to verify this prediction before final bond release. CCC has not proposed a monitoring point or points that would allow such a verification to be made. a. Please elaborate on the vertical separation(refer also to item 68 in this letter)of the Trout Creek Sandstone, and the thickness and lateral continuity of the Km layer in the text. The discussion should include the impacts of the faults mentioned in item 10 of this letter on the integrity of the confining layer. CCC added text to section 2.04.6 of the proposed revised text(under the sub-heading"stratigraphy" addressing the thickness and lateral continuity of the Trout Creek Sandstone and the Km layer,with reference to the 2005 WMC report in Exhibit 7, Item 21.Further text was added under the sub-heading"structure" discussing faults (refer to item 73 in this letter).No further action is required on this item until item 73 has been