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71 <br />The habitat associated with the Purgatoire River and its surrounding areas <br />will be protected by the Operator under the current plans. <br />Protection of Hydrological Balance <br />Probable Hydrologic Consequences <br />Probable hydrologic consequences of the mine are attributable to the following <br />operations: <br />• Consumption of water to run the preparation plant <br />• Dust control during mining <br />• Subsidence <br />• Surface disturbances <br />• Operation of the RDA <br />• Mine dewatering. <br />Surface disturbances at the facilities area and coal shipping operations will result <br />in an increase in total suspended solids (TSS), which will be treated by <br />sedimentation ponds prior to discharge to the Middle Fork of the Purgatoire <br />River. Water quality impacts to the Purgatoire River and the alluvial aquifer from <br />surface operations are expected to be similar to those currently observed from the <br />mine (i.e. an average increase of about 40 mg/l TDS in river water downstream <br />from the mine, and 400 to 500 mg/1 TDS increase over background in alluvium <br />down gradient of the RDA). <br />The area overlying the mine workings has the potential to subside. The <br />maximum extent of subsidence fracturing with increased vertical transmissivity is <br />projected to extend 195 feet above the top of the highest mined coal. A minimum <br />thickness of 450 feet of overburden lies between the top of the Apache seam and <br />the base of area drainages. The zone of increased vertical transmissivity is not <br />expected to impact surface water. A zone of continuous deformation will be <br />present from about 195 feet above the coal to 50 feet below ground surface. No <br />hydrologic impacts or only temporary minor changes in water level are expected <br />to occur in the continuous zone. No flow or water quality impacts are expected to <br />occur to surface water including springs and seeps due to subsidence from mining <br />in the Allen and Apache seams. <br />Well records from CDWR indicate that there are 19 permitted wells in the Raton <br />Formation within a one mile radius of the permit boundary. The wells vary in <br />depth from 30 to 750 feet, and have completion water levels ranging from 5 to <br />598 feet bgs. A study by Watts (reference 2006b in exhibit 8(4)) evaluated the <br />potential for groundwater pumping from coal seams in Las Animas County to <br />impact water levels in wells that are used for water supply. He noted that <br />because the permeability of stratified sedimentary rocks generally is greater <br />parallel to bedding than across bedding, the drawdown of water levels in coal <br />Section 2.05 RN -6 10/17/2016 <br />