2007-07-30_GENERAL DOCUMENTS - C1981041

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"Mining coal in the Mesaverde Group temporarily will dewater the rock adjacent to the underground mine. This rock will become rubblized and increase the permeability ofthe rock thus increasing the flow of groundwater into the area." Inflow in the mine is expected to increase as a result with a secondary effect of lowering the potentiomettic surface temporarily. Water levels should return to pre-mining levels after the underground mine is sealed, with saturation occurring after several years. The mine utilized limited extraction methods in the Cottonwood and Rapid Creek areas. Past monitoring of the alluvium of Rapid and Cottonwood Creeks has not detected any significant depletion of alluvial water in either creek system, and no significant depletion is anticipated. There is no beneficial use of the groundwater in the mine permit area or vicinity. Mine inflow quantity has been documented in past Annual Hydrology Reports. [t has been demonstrated that most of the mine inflow waters originate in the new faces of virgin coal seams. As these seams are mined, the coal seam aquifer is dewatered. New areas of the mine have a higher inflow rate than older, developed ones, which dry out after the area has been developed. Additional water originates from the Mesaverde sandstone lenses as they aze dewatered by mining activity combined with subsidence. The operator has committed to a mitigation contingency plan for downstream users should they be effected by subsidence. Groundwater Ouantity: Effect on the Colorado River Alluvial Aquifer Water quantity in the alluvium of the Colorado River aquifer is minimally affected by the mine operations. The quantity of surface water and groundwater in the Roadside North and South Portal facility areas and adjacent aeeas will not be adversely affected due to the recycling nature of the ground and surface waters in the alluvial valley floor. Mining did not occur beneath the Colorado River alluvial valley floor. Groundwater inflows to the South Mine workings discharge by gravity flow through a dewatering pipe near the reclaimed North Decline, at Discharge Site O 16, into the Colorado River. Approximately 0.7 cfs of mine water is discharged into the Colorado River. III. Topsoil Soils resource information found in Volume 2, Tab 9, and the topsoil salvage and redistribution plan in Volumes 3 and 5, Tabs 13 and 14, of the application have been reviewed for compliance by the Division. Since mining at this operation began prior to the Surface Mining Control and Reclamation Act, no topsoil was salvaged in construction of the mine benches. Topsoil from the loadout azea was used to build the loadout stacker pad, although a small amount was stockpiled. The majority of the topsoil salvaged was removed from the location of the Cameo refuse piles. Soils in the general area are commonly high in sodium and occasionally saline. This is reflected in the spazse vegetation which is primarily composed ofsalt-tolerant species and species such as greasewood, which are commonly found growing in sodic soils. The analyses of the stockpiled soil and the material presently on the surface of the disturbed areas reflect the saline and sodic conditions of the Permit Revision No. 3 Permit No. C-1981-041 July 30, 2007 Page 33