2015-07-21_REVISION - C1982056 (2)

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Twentymile Coal, LLC. Page 13 July 21, 2015 b. Division's response: i. Revised page 2.06-25.7 references two reports in Exhibit 7e-2 and 7e4. The Division believes TC meant to reference Exhibit 4e-2 and 4e-4. Please revise this page accordingly. ii. Revised page 2.06-25.8 indicates that TC conducted a vegetation study on the Fish Creek AVF; this study is located in Exhibit 7J-1 of the permit. This page indicates that productivity between the AVF bottomlands and uplands are not significantly different. However, upon review of Exhibit 7J-1, the data indicates the production from the valley floor is about twice that of the upland area. Given this, the statement made on Page 2.06-25.8 does not appear to be correct. Please revise this page and evaluate if the conclusion drawn is still accurate. iii. The State of Colorado owns a significant amount of land in the area to be subsided. Please provide documentation that the reduction in pastureland/grazing land as a result of subsidence induced flooding will not significantly interrupt, discontinue or preclude agricultural activities on State land. iv. Revised Page 2.06-25.9 indicates that there are areas where sub -irrigation occurs within the AVF. Map 5 of Exhibit 4e depicts areas where sub -irrigation occurs along Fish Creek. Please evaluate the impact mining in the WCR will have on these areas that are sub -irrigated and to what degree mining may interrupt, discontinue or preclude agricultural activities on these areas. v. Revised Page 2.06-205.9 indicates that water quality is monitored at Station 900 on Foidel Creek downstream of previous mining in the Eastern Mining District and the proposed mining in the WCR. This station appears to be upstream of the proposed mining in the WCR. Please revise this page accordingly. 8. Please submit an environmental monitoring program that includes hydrologic monitoring, vegetation monitoring and subsidence monitoring similar to the one submitted as Exhibit 4e-7 (Fish Creek AVF Monitoring Program) for mining in the NMD. This plan should be designed based on mining of the Wolf Creek Reserve and the projected impacts on the AVFs of Foidel and Fish Creek. a. TC's response: Please recognize that extensive resource and impact monitoring and analyses were completed to validate the initial mining activities and related subsidence effects for the Fish Creek AVF. The results of these extensive monitoring and related analysis efforts confirmed that the projected surface subsidence and related subsidence effects on surface and ground water hydrology and vegetation communities were consistent with actual measured subsidence and subsidence effects. All subsequent mining, subsidence evaluations, monitoring requirements, and impact analyses tiered off and were built on this foundation of confirmed mining and impact results. Given these