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ENERGY FUELS COAL, INC. - SOUTHFIELD MINE ' TR35 -CONVERT NORTH DEWATERING WELL TO MONITORING WELL RESPONSES TO CDMG 8/21/03 ADEQUACY COMMENTS 7) Based on the derniption of the dewatering operations on pager 2.05.3-72 to 74, its not clear what hydraulic ronnectious exist that will effect the water leveb' at the propared location. Please describe in the groundwater monitoring section exacdly where the North Dewatering Well is situated in the undegmund flow system. From where does water accumulate in the 1-North Section? Response: In general ground water flows in the area trend to the west and north toward the axis of the Chandler Syncline and northward to the Arkansas River (page 2.04.7-9 of the plan document). There are no stratigraphic units that can be considered ground water aquifers and ground water movement is limited and discontinuous in the area. Therefore, any ground water flows within the abandoned mine workings wiIl generally be con[roIled by the configuration, connections, relative gradients and any hydrologic barriers within the mined-out areas. General descriptions of ground water inflows and mine flooding are provided in the PHB and PHC sections of the plan document (i.e.: pages 2.05,6-22 and 23, 31 through 35, and 40 through 46. As requested, the hydrologic monitoring section (page 2.05.6-53) has been revised and expanded to include a brief description of anticipated ground water inflows, water movement, and mine flooding in the vicinity of the North Well. Copies of the revised text accompany these responses for replacement in the plan document. 2) Is it predicted that water will flow out of the 1-North Section once the level reaches some particular level? If it will exit the 1-North Section, where will it flow? Response: Please refer to previous response and the referenced description of ground water inflow, movement, and flooding. 3) The proposed well was added to the Probable Hydrologic Consequences section of the permit. Please include there a prediction of what data from that well will show That is, bared on the most recent data concerning mine inflows and the operator's knowledge of the mined-out sections, what is anticipated at this location? Response: Mine inflow rates, mine flooding, and discharge from flooded mine workings to the ground water system will all occur a varying rates, dependent on climatic conditions and other factors. Given these considerations, it is not realistic to predict what will happen at a specific location in the abandoned mine workings beyond the general projections cuxrendy provided in the PHC section of the plan document. What we do know is that mine inflows will continue, probably at some rate between the 5 ac-ft/yr recently documented by inflow monitoring under drought conditions (2001 Water-Year) and the 70 ac-ft/yr dewatering pumping rate documented during active operations. Inflows will result in gradual flooding of the abandoned mine workings, with gradual flooding of closed mine areas (i.e.: areas isolated by seals) due to direct inflows in those areas and more rapid flooding of the lower portions of those areas where open workings and elevation differences allow water to move from upgradient areas. As abandoned mine areas flood, some seepage wiIl occur to the general ground water system due to fracture flow, movement through natural cleats in the coal, and increased hydraulic pressures. Flooding will continue until either the abandoned mine workings fill or a dynamic equilibrium is established between inflows and seepage (more likely), Based on the volume of the mine workings (estimated at 5,700 ac-ft, page 2.05.6-32 of the plan document), an inflow rate of 20 ac-ft/yr, and assuming no ground water seepage, it would take approximately 300 years for the abandoned mine workings to totally fill.