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K. Probable Hydrologic Consequences <br /> Under Rule 2.07.6(2)(c), the Division is required to make an assessment of the <br /> probable cumulative impacts of all anticipated coal mining in the general area, on <br /> the hydrologic balance and to make a finding (as discussed in Section A of this <br /> document) that the operations proposed in the permit application have been <br /> designed to prevent material damage to the hydrologic balance outside of the <br /> proposed permit area. This section of the findings document is divided into the <br /> following subsections: Description of the Hydrologic Environment, Probable <br /> Hydrologic Consequences of the West Elk Mine, and Summary and Findings. A <br /> separate Cumulative Hydrologic Impact Study (CHIS) is available for review at <br /> the Division of Minerals and Geology. The Cumulative Hydrologic Impact Study <br /> (CHIS) filed at the DMG office assesses the projected cumulative hydrologic <br /> impacts of all anticipated mining operations in the general area of the West Elk <br /> Mine on the North Fork of the Gunnison River Valley. <br /> 1. Description of the Hydrologic Environment <br /> a. Regional Geology <br /> For information regarding regional geology, see Section A, Description <br /> of the Environment, Geology in this Findings Document. <br /> b. Groundwater <br /> Seven categories of potential aquifers occur in the Somerset Coal Field. <br /> These are: 1) the alluvial and terrace deposits associated with the North <br /> Fork of the Gunnison River; 2) the localized, shallow alluvium along <br /> creeks tributary to the North Fork; 3) the discontinuous, lenticular and <br /> laminar sandstones of the Mesaverde Formation; 4) the Rollins <br /> Sandstone; 5) the coal seam; 6) shallow colluvial surficial deposits; and <br /> 7) fracture zones in bedrock. <br /> The most continuous sandstone aquifers of any significance in the <br /> region are the Rollins Sandstone and the massive sandstone separating <br /> the Upper and Lower Coal Members of the Mesaverde Formation. The <br /> Rollins Sandstone has been considered an aquifer of potential regional <br /> importance, because of its areal extent and potential yielding capability. <br /> However, available data indicate that the Rollins is a marginal aquifer <br /> in terms of yield and water quality. One pumping test conducted on the <br /> Rollins sandstone in the vicinity of the mine indicates that the formation <br /> was capable of producing only approximately 3 gpm. This is further <br /> documented in the vicinity of the Orchard Valley Mine where it is <br /> reported that drill holes which penetrated the Rollins Sandstone had an <br /> insufficient yield to sustain groundwater supply wells. <br /> 30 <br />