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<br /> <br />V[?t. A1'vv`al '!alley Floor; - Rules 2.06,3 and 4,24 <br />Alluvial `1a11ey Floor Identification - <br />Information retarding alluvial valley floors in the permit and adjacent area <br />is provided nn Pages 785-6 through 785-24 and Map 6 and 51 of the updated <br />C-81-071 permit document. Map 6 was utilized by the Division in making the <br />alluvial valley floor determinations set forth below. In addition, certain <br />information regarding alluvial valley floors downstream from the permit area <br />on Fish Creek, Foidei Creek, Middle Creek and Trout Creek was presented in <br />Twentymile Coal Company's Life-of-Mine Permit Revision application for the <br />Foidei Creek Underground Mine (C-82-056) and is referenced in this document. <br />Potentially affected portions of Foidei Creek, Middle Creek, Fish Creek and <br />Lower Trout Creek stream valleys have previously been evaluated with respect <br />to AVF criteria in a number of coal permits, including Twentymile Coal <br />Company's Foide7 Creek .Mine (C-82-055) and Fish Creek Tipple (C-81-036) and <br />Colorado Yampa Coal Company's Eckman Park, Mine No. 1, and Mine No. 2 <br />(C-81-071) and Mine No. 3 (C-84-062). <br />To summarize the previous AVF findings made by the Division; Fish Creek <br />alluvial deposits within and below the proposed permit area, an alluvial body <br />in Sections 21, 22 and 28 (T5N, R86W) on Foidei Creek below the proposed <br />permit area, alluvial deposits in the vicinity of the Foidei Creek.i"i~idle <br />Creek confluence downstream to Trout Creek, and alluvial deposits on Trout <br />Creek downstream to the Yampa River were determined to be alluvial valley <br />floors. <br />Fish Creek was determined to be an AVF based on existing and potential flood <br />irrigation and sub-irrigation capabilities and findings were made that farming <br />would not be interrupted, discontinued or precluded; proposed operations would <br />not cause material damage to quantity and quality of surface and ground water <br />that supply the AVF, and the proposed operation would be conducted to preserve <br />the essential hydrologic functions of the AVF. <br />An alluvial body on Foidei Creek downstream from the permit area below the <br />water gap in Sections 21, 22 and 28 (T5N, R86W) was determined to be an AVF <br />based on an assumed capability to support sub-irrigation. As in the case of <br />Fish Creek, findings were made to the effect that the AVF would not be <br />negatively impacted by the proposed mining operation. An alluvial body <br />upstream from the water gap within the permit area in sections 28, 29, 31 and <br />32 (T5N, R86W) was determined not to be an AVF based on a finding of <br />insufficient water to support flood irrigation and a determination that <br />sub-irrigated areas were less than 10 acres in extent and supported species <br />which were not agriculturally useful, <br />Alluvial deposits in the vicinity of the Foidei Creek/Middle Creek confluence <br />and alluvial deposits on lower Middle Creek and Lower Trout Creek (below <br />Middle Creek confluence) were found to be alluvial valley floors because of a <br />presumed capability to support flood irrigation and sub-irrigated crops. <br />Again, findings were made that the alluvial valley floors would not be <br />negatively impacted by the proposed mining operation. <br />17 <br />