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The language of Stipulation No.7, pertaining to collection and reporting of <br />hydrologic monitoring data (the submittal of an AHR), has been incorporated into <br />pages 2.05.6-52 through 2.05.6-54 of the permit application, and is considered <br />satisfied. <br />These long-term data records are necessary to identify any pattern of water <br />quality changes. EFCI's hydrologic monitoring plan should be adequate to <br />evaluate possible hydrologic impacts (Rule 4.05.11(1)(b)). <br />It was previously determined that the Southfield Mine workings had the potential <br />to deplete the quantity of groundwater through mine-induced groundwater flows. <br />Estimates were that the mining operation would induce inflows by dewatering the <br />coal seam and the associated roof and floor strata as the mine workings <br />advanced. In addition, overlying aquifers could be dewatered through <br />subsidence-related fractures. Locally perched groundwater aquifers in strata <br />above the workings could be dewatered through subsidence cracks or fractures. <br />Thus water would drain down through the fractures to the voids created by the <br />mine. <br />The greatest potential effect on ground water is for perched aquifers in the <br />Vermejo and the overlying Raton Formations to be dewatered by subsidence. <br />Wells that use these perched aquifers could experience drawdown effects. <br />However, due to the low hydraulic conductivity of the associated aquifers, the <br />fact that the aquifers in this area tend to be laterally discontinuous and the <br />effects of past surface and underground mining, ground water impacts (both <br />magnitude and extent) are difficult to predict. The operator is obligated to <br />comply with Rule 4.05.15 pertaining to water rights and replacement if an owner <br />is injured as the result of the operation. The ground water monitoring plan has <br />been designed to identify ground water impacts before they extend to water <br />supply wells. These measures will ensure a better understanding of the impacts <br />to the ground water system and protection of water resources in the future. <br />The existence of the mine workings will permanently modify the pattern of <br />ground water flow. The flooded mine constitutes a region of essentially infinite <br />permeability that will tend to cause ground water to preferentially pass through <br />the workings. The water passing through the flooded mine may be degraded in <br />quality, relative to that in the undisturbed strata. <br />Another potential ground water impact is due to subsidence and the fracture- <br />related drainage of surface water bodies into the subsided areas. These surface <br />water bodies would be the mine water ponds, ephemeral drainages, and the <br />perennial Newlin Creek. Dewatering of the ponds would short-circuit the water <br />system during mining, which is not considered a significant impact. Also, the <br />effects to ephemeral drainages would be minimal. However, diversion of stream <br />flow from Newlin Creek to the underground workings may be significant. The <br />interception of surface water or shallow ground water by underground workings <br />presents a potential impact to water availability in Newlin Creek. However, as <br />Page 25 of 36