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72 <br />seams would have the greatest potential for interfering with nearby water - <br />supply wells in areas where there is little vertical separation between the coal <br />seam and the well production intervals. The analysis assumed that a vertical <br />separation of 100 feet between coal seam and water supply wells would be <br />protective of water supplies, but it was careful to note that the required separation <br />would depend on local geologic conditions. Mining related subsidence will <br />increase vertical permeability for up to 195 feet above the highest mined coal. <br />Wells that produce from 100 feet or higher above the zone of increased vertical <br />permeability are not likely to be adversely impacted by mining. <br />Two bedrock wells are located near the planned mining area in the Allen <br />Seam. The wells are in the northeast half of Section 24, T33S, R68W. Well <br />number 284213 is a monitoring well owned by NECC and is completed in the <br />Allen Seam. The well is 442 feet deep and is designated as NE -1-10 for the <br />monitoring program. The other bedrock well (permit number 264440) is 200 feet <br />deep and is completed in an unidentified coal bed. The owner of record for the <br />well is Helen Armstrong. Four shallow alluvial wells (12, 13, 14 and PAW -9 on <br />Map 8) are also are also located in the northeast half of Section 24, T33E, R68W. <br />Wells 12, 13, and 14 are on land owned by J.I. Vialpando. Well PAW -9 is a <br />monitoring well owned by NECC. Mining of the Allen Seam may have the <br />potential to reduce water levels and impact water quality in the Armstrong well. <br />In the event that water in the well is impacted by mining, the water supply will be <br />replaced with water from the city of Trinidad (city water). Well NE -1-10 is <br />designed to monitor potential impacts to groundwater in the mining horizon, <br />and impacts to water levels or water quality in the well are not an issue with <br />respect to water supply. Wells 12, 13, 14 and PAW -9 are situated more than 400 <br />feet above the planned mining horizon, and impacts to water quality and <br />availability are not anticipated to these wells. In the event that unanticipated <br />impacts occur the water supply will be replaced with city water as discussed in <br />2.04.7(3). <br />Based on the previously observed groundwater inflows to the Golden Eagle and <br />New Elk mines, inflow to the New Elk Mine during mining of the Allen and <br />Apache seems is expected to be between 0.04 and 0.1 gpm/acre. Inflow along <br />faults (to the extent that they are present) could modify the range upward. The <br />maximum observed inflow along a fault is 100 gpm at the Golden Eagle Mine. It <br />is likely, however, that mine inflow will be less than predicted based on historical <br />observations because of extensive dewatering of the coal seams related to CBM <br />production. Mine dewatering has the potential to draw water levels down in <br />Allen and Apache seams by 200 or more feet in the permit area. Water levels in <br />the coal seams are currently depressed by groundwater pumping for CBM <br />production. Mine dewatering will incrementally increase the currently observed <br />drawdown in the Allen and Apache coal seams. Water level data from packer <br />testing indicate that steep vertical gradients currently exist in the strata adjacent to <br />coal seams. The steep gradients are related to mine dewatering and/or CBM <br />production and suggest that there is limited potential for propagation of <br />Section 2.05 RN -6 10/17/2016 <br />