2007-11-01_PERMIT FILE - C1982056A (4)

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RESPONSE • The Fish Crcek floodplain within the proposed permit area appears to meat the geomorphic criteria of an alluvial valley floor. For portions of Fish Creek, however, applicability of hydrologic and agricultural significance criteria has never been conclusively determined. The following discussion of mining related impacts on the Fish Creek AVF is based not on applicability of regulatory AVF criteria to Fish Creek in its entirety but rather on agency designations as previously discussed. Min' ~o operations are not expected to significantly affect the alluvial valley floor or waters that supply the alluvial valley floor. Mining will not interrupt, discontinue or preclude fanning on the alluvial valley floor and will not materially damage the quantity and quality of water in surface and underground water system that supply the alluvial valley floor or portions of it. The minimal effects of mine subsidence or mine dewatering on the alluvial valley floor, as described under Rules 2.05.6(3), Protection of the Hydrologic Balance, 2.04.7, Hydrology Description, and 2.05.6(6), Subsidence Survey, Subsidence Monitoring, and Subsidence Control Plan, will not negatively impact agricultural activity. Based on this information, subsidence related impacts will be of limited magnitude, will occur progressively during and shortly after coal extraction, and will be effectively mitigated by the natural response of the dynamic stream system. Continuous discharge of water from the underground into the stream system will have a negligible impact under normal conditions and will not result in unacceptable levels of dissolved solids with regard to agricultural and forage crop tolerances even under worst case conditions. Dewatering will have a positive effect on alluvial valley floor productivity downstream from the point, especially during years of low stream flow. The location of road crossings through the Fish Crcek alluvial valley floor were chosen to cause the least disturbance • to the valley floor. As presented on Map 15, Alluvial valley Floor and Water Rights, the areas to be affected are narrow and should not limit any of the functions of the AVF. Specific details of road construction will be submitted to CMLRD for evaluation and approval prior to the conswction. In view of these facts, it is proposed that a negative determination be made for this Rule. As TCC continues to expand its operation into the Northern Mining District (NMD) additional information is required to meet the requirement of the above regulation. It should be understood that TCC will be subsiding segments of the Foidel Creek and its alluvial valley floor as it mines the coal reserves located in the NMD. The result is that the portion of the valley floor will be flooded and the agricultural activities precluded. Exhibit 4c-2, Kaman Tempo Report- Foidel Creek Mine, November 1987, provides a detailed information concering the Foidel Creek AVF. The report was updated with a soils investigation preformed by Habitat Management, and the report is presented in the Exhibit 4c~, Fish Creek Alluvial Valley Floor Soil Investigation. The data derived from the backhce soil tests pits was used to conduct Exhibit 4c~, Figure 1, Fish Creek AVF Profile # 1, Figure 2, Fish Creek AVF Profile #2, Figure 3, Fish Creek AVF Profile #3, Figure 4,and Fish Creek AVF Profile #4. The figure provides a look at the physical wnfiguration of the valley floor and Fish Creek. APPROVED JUN 2 8 2000 PR 99-OS 2.06-13 11/17/99