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Rob Zuber <br />Page 5 <br />October 14, 2015 <br />17. 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 <br />layer. The Division concurs that, given those conditions, the probable hydrologic consequence of <br />the activity proposed in PR -4 on the Trout Creek Sandstone is that it will not be impacted; <br />however it will be necessary to verify this prediction before final bond release. CCC has not <br />proposed a monitoring point or points that would allow such a verification to be made. <br />a. Please elaborate on the vertical separation [refer also to item 5 in this letter] of the <br />Trout Creek Sandstone, and the thickness and lateral continuity of the Km layer in the <br />text. The discussion should include the impacts of the faults mentioned in item 10 of <br />this letter on the integrity of the confining layer. <br />b. Please provide references in the text to supporting data. <br />c. Please propose a monitoring point(s) that will allow the prediction of "no impact" to <br />the Trout Creek Sandstone to be verified. <br />18. CCC proposes to discharge a very significant volume of water from dewatering wells (200- <br />300gpm during years 1-3; 100-200gpm during years 4-8; <100gpm after year 8); potentially in <br />the region of 3000 acre -ft over 8 years. <br />a. Please clarify the legal right of CCC to this groundwater. <br />b. Please describe how the water will be used or discharged. (i.e. Where will it be <br />pumped to? What are the anticipated impacts to the receiving drainage?) <br />c. Please propose monitoring points that will allow the drawdown cone adjacent to the <br />pit to be characterized during the dewatering and recovery phases of the operation, <br />and predictions made in the PHC to be verified. <br />d. Please address item 1 in the initial adequacy review letter. <br />Rule 2.06.8 —Alluvial Valley Floors <br />19. Section 2.06.8 of the PAP discusses operations on areas, or adjacent to areas, including alluvial <br />valley floors. The text describes a field investigation and technical evaluation of all drainages <br />containing streams within and adjacent to the permit boundary, including the Collom Gulch, <br />little Collom Gulch and West Fork of Jubb Creek drainages. The conclusion is that alluvial <br />materials are present in these drainages, but that they do not meet the definition of Alluvial <br />Valley Floor. <br />Please ensure that the discussion in this section is consistent with the areas of Quaternary <br />Alluvium and Irrigated Land shown on Maps 7A and 10113 <br />Rule 2.10 — Maps and Plans <br />20. Map 1013 shows Hydrologic Features and Monitoring Locations. The legend shows a symbol for <br />"Area of Quaternary Alluvium", and such areas are shown as existing in the Wilson Creek and <br />Good Spring Creek drainages. None are shown in the west of the proposed permit area. <br />