2007-07-30_GENERAL DOCUMENTS - C1981041

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Since no agricultural information has been provided from any ofthe areas designated as alluvial valley floors, all the areas will be assumed to be agriculturally significant, and all three alluvial valley floor findings will be made. Rapid Creek Alluvial Vallev Floor -Findings The proposed surface coal mining operations would not interrupt, discontinue, or preclude farming on an alluvial valley floor (4.24.3(1)). The area designated as alluvial val ley floor lies outside of the permit area, downstream from the proposed operations. As a result, there would be no surface disturbance within the AVF, and the area would not be undermined. 2. The proposed surface coal mining operations would not materially damage the quantity and quality of water in surface and undergroundwatersysterns that supply these alluvial valley floors or portions of alluvial valley floors (4.24.3(3)). The Rapid Creek alluvial valley floor receives the water supply from the Rapid Creek/Cottonwood Creek stream system. Since no surface facilities are located within this system, and no disturbed runoff or mine water would be discharge to Rapid Creek or Cottonwood Creek, the proposed operations will not affect water quality. The Division has estimated that stream flow depletion in the absence of flow through fractures, either natural or as a result of subsidence, would be Tess than 0.003 cfs. Such a minor loss would not be detectable. The permittee has proposed a limited extraction mine plan beneath the streams, and subsidence effects would not be expected in these areas. No major natural fractures have been identified in the permit application. Minor fractures are undoubtedly present, but may not be open to the passage of groundwater. The required surface water and mine water monitoring will detect any unanticipated change in the existing hydrologic system. Surface coal mining and reclamation operations would be conducted to preserve, throughout the mining and reclamation process, the essential hydrologic functions of the alluvial valley floor (4.24.2(1)). The essential hydrologic functions of the Rapid Creek alluvial valley floor are those geologic, hydrologic, topographic, and soil chazacteristics that give the area the ability to support flood irrigated agricultural activities. Since no mining activities would take place within the AVF, the geologic, topographic, and soil characteristics of the AVF would be unaffected. Rapid Creek and Cottonwood Creeks would be undermined under a limited extraction plan and mining would not effect the surface water system that supplies the alluvial valley floor. Colorado River Alluvial Vallev Floor -Findings The proposed surface coal mining operations would not intercupt, discontinue or preclude farming on an alluvial valley floor that is ircigated or naturally subircigated. The area designated as alluvial valley floor lies outside of the permit area, downstream from the proposed operations. As a result, there would be no surface disturbance within the AVF, and the area would not be undermined. No ircigation occurs along this stretch of the river where the Permit Revision No. 3 July 30, 2007 Permit No. C-1981-041 Page 57