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Future Inflow Estimates All of the future mining will be in areas of high cover with almost all of it under greater • than 1000 feet and small aeeas of 700 to 1000 feet of cover, None of the future mining will be in areas of steep dip or large structural flexure. All future mining areas will be more than 3000 feet from a subcrop of the coal. Therefore, it is not anticipated that any new significant sustained flows will be encountered. Therefore, additional inflows aze expected to be the same or lower than those measured per unit areas in other parts of the mine. Since the average cover in the NMD and NWMD will be greater than 1000 feet, lower unit inflows are anticipated. Using the factor of 0.027 gpm/feet developed for the WMD, the inflow to the EMD (excluding 6 Right) will increase to 85 gpm due to the additiona1400 acres to be affected plus 65 gpm from the 6 Right inflow for a total of 150 gpm. These estimates were compared against measured mine discharges and water balance calculations and a good match was found. Approximately 6500 total acres had been mined by the end of 2002. For the 2002 inflow study, flows included 20 gpm from the North East Mains, 55 gpm from the WMD, 85 gpm from the EMD, measurements of 25 gpm from the NW Mains raise bore and 65 gpm from 6 Right, for a total of 250 gpm. Removing the two NW mains and raise bore measurements yields 160 gpm. When 160 gpm is divided by the total acreage of 6500 a factor of 0.025 gpm/acres is obtained. The addition of approximately 7,200 acres of the NMD and NWMD will yield an estimated 194 gpm. The estimated total ground water inflow will increase from 250 gpm in 2003 to approximately 444 gpm at the end of mine life (Exhibit 49, Table E49-4). Mine Water Balance The inflows and outflows from the mine can be estimated to determine a mine water balance. Historically two different mine water balance conditions have existed: 1) when water has been stored in the sump at the northwest comer of the WMD and 2) when all water that entered the mine has been pumped out. From the beginning of mining to July 1996, the mine has been kept dewatered except for the sealed 1~` South Panels. From July 1998 to August 1998, the northwest corner of the WMD was allowed to flood with groundwater inflow to the SWD and other water pumped into the SWD from the NMS and the EMD. Since August 1998, some pumping of the WMD sump has been conducted. • The water balance consists of these main components: • Groundwater inflow to the workings • Water pumped into workings for use by the equipment for water sprays and cooling • Water pumped out of the workings via Site 109 (NMS) and Site 115 (at the Fish Creek Borehole, located in the WMD) • Water removed from the mine as added moisture to the coal • Water added to storage in the undergound sump at the Fish Creek Borehole, located in the WMD. The water balance for water years 1993 to 2002 is presented in Exhibit 49, Table E49-3 and shown on Map 16. The water balances were calculated beginning when tong-wall mining started. The inflows to the MNS were estimated to be constant at 45 gpm based upon past mine inflow studies. For years 1989 to 1993 inflows to the WMD were calculated based upon the total of the other inflows minus the outflows. In 1994, the pool at the Fish Creek borehole began to expand. For water years 1994 to 2002 the excess inflow was assigned to the sump and the WMD, inflow was estimated to be 55 gpm based upon the Mine Inflow Surveys. The inflows to the EMD were estimated from the areas mined and the actual inflow measured. In 1995 approximately 200 acres were affected by longwall mining yielding an estimated 5 gpm. Some fault inflows where encountered at the end of the water year. In 1996, approximately 800 acres in the EMD were affected by mining yielding approximately 20 gpm including the fault inflows. In 1997, excluding the inflows from 6 Right, a total of approximately 1400 acres were affected for 35 gpm plus 10 gpm from the Southeast Submains. In 1998, excluding the inflows from 6 Right, a total of approximately 2000 acres were affected yielding an estimated 55 gpm plus 10 gpm from the Southeast Submains, which are located in the EMD. All the water that flows from the active longwall and continuous miner equipment plus all the inflows to the EMD excluding the 6 Right inflow aze • collected in a sump at 10 Right. The sump has been maintaining a constant pool level by pumping at approximately 170 gpm since 1998. The estimated inflows to this area are 65 gpm from groundwater and 111 gpm PR 03-06 2.05-137 05/07/03