2011-06-29_GENERAL DOCUMENTS - C1981018

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amount of water available annually, as estimated through this method, indicated that Scullion Gulch warrants further consideration as a potential alluvial valley floor. Sub - irrigation As with Red Wash, the presence of sub - irrigation along Scullion Gulch was investigated by the permittee based on the type of vegetation present along the drainage. The permittee has identified a big sage brush - greasewood community along the entire length of unconsolidated alluvial deposits identified on Map 102, and concludes that water is available to the vegetation "on a limited and sporadic basis ". The big sage brush - greasewood community, however, is sparser compared to that community found along Red Wash, indicating the availability of subsurface water is much more limited in Scullion Gulch. Further evidence of the general lack of sub - irrigation can be gleaned from the permittee's surface facilities geotechnical investigation, contained in Illustration 18 of the permit application. Six exploration holes, sited at the proposed "D" portal area, were drilled within the alluvial body associated with Scullion Gulch. Although all the holes fully penetrated the alluvium, no evidence of alluvial groundwater was encountered. This information, coupled with the sparse occurrence of deep- rooted vegetation, generally indicates that sub - irrigation is of minimal consequence along Scullion Gulch. Scullion Gulch Alluvial Valley Floor Determination The Division and OSM concluded that Scullion Gulch is not an alluvial valley floor. White River Alluvial Valley Floor Determination On the basis of available annual water yield, the presence of unconsolidated stream laid deposits, the availability of supplemental moisture through sub - irrigation, and the presence of established irrigated lands, the Division and OSM identify the White River and its associated alluvial deposits as an alluvial valley floor. The permittee has supplied sufficient information to address material damages to the White River AVF. The majority of the White River lies outside of the permit area. Mining will not take place beneath the river or its alluvial deposits. The permittee has adequately demonstrated that bedrock contributions of ground water from the area to be mined are insignificant in relation to the flows observed in the White River. Flows to the White River from Red Wash and Scullion Gulch, which may be impacted by mining, are also insignificant in relation to the flows observed in the White River. By minimizing disturbances to Red Wash and Scullion Gulch during mining, the White River will not be subject to material damage via either of these drainages. At the time of initial permit issuance, Kenney Reservoir, which presently exists in the project area, had not yet been filled. As such, the original findings document for the Deserado Mine contained an assessment of the potential for material damage to occur to Deserado Mine Permit Revision 07 C- 1981 -018 42 29 June 2011