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of 250 gpm. Excluding the temporary high inflows from 6-Right, and the'raisebore yields '160 gpm for mined
<br />areas. When 160 gpm is divided by the total acreage of 6,500 a factor of 0.025 gpm/acres is obtained. Using this
<br />updated inflow rate, the addition of approximately 4,050 acres for the remainder of the' NMD and initial
<br />• development in the WMD yields an additional 100 gpm. Total mine inflows aze, therefore, projected at
<br />approximately 260 gpm. With subsequent development and mining of the remainder of the WMD, total mine
<br />ground water inflow is projected to increase to approximately 440 gpm at the end of the mine life (Exhibit 49,
<br />Table E4911).
<br />Mine Water Balancei Inflows and outflows-for the mine can be estimated to determine a ptine water balance.
<br />Historically two different mine water balance conditions have existed: ])'When water has been stored in the sump
<br />at the northwest comer of the SMD and 2) When all water that entered the mine has been pumped out. From the
<br />beginning of mining to July 1996, the mine was kept dewatered except for the sealed 1°' South•Panels. From July
<br />1998 to August 1998, the northwest comer of the SMD was allowed 4o flood, with groundwater inflow to the SMD
<br />and other water•pumped into the SMD from the NMS and the EMD. Since August 1998, sealed workings in the
<br />southern portion of the EMD have been established as a temporary water storage area. Some pumping of and
<br />discharge from the SMD and EMD sumps, has been conducted to maintain the water level in the flooded workings
<br />below the seals. With installation of the new longwall in 2006, mine water use increased to the point where
<br />discharge was no longer necessary to maintain stable water levels.
<br />The water balance consists of these main components:
<br />• Groundwater inflow to the workings
<br />• Water pumped into workings for use by the equipment foi water sprays and cooling
<br />• Water pumped out of the workings via Site 109 (NMS) and Site 115 (at the,Fish Creek Borehole,
<br />located in the SMD)
<br />• Water removed from the mine as added moisture to the coal
<br />• Water added to storage in the underground sump at the Fish Creek Borehole, located in the SMD
<br />• The water balance for water years 1993 to 2002 is presented in Exhibit 49, Table E49-3. The original water
<br />balance was calculated shortly after longwall mining started. The inflows to the NMS were estimated to be
<br />constant at 45 gpm, based upon past mine inflow studies. For years 1989 to 1993 inflows to the SMD were
<br />calculated based on the total of the other inflows minus the outflows. Tn 1994, the pool at the Fish Creek borehole
<br />began to expand. For water years 1994 to 2002, the excess inflow was assigned to the sump and the SMD, inflow
<br />was estimated to be 55 gpm, based on the current Mine Inflow Surveys, at that time.
<br />The inflows to the EMD were estimated from the areas mined and the actual inflow measured. In 1995
<br />approximately 200 acres were affected by longwall mining, yielding an estimated 5 gpm. Some fault inflows were
<br />encountered at the end of the water year. In 1996, approximately 800 acres in the EMD were affected by mining,
<br />yielding approximately 20 gpm, including the fault inflows. In 1997, excluding the inflows from 6-Right, a total of
<br />approximately 1,400 acres were affected, yielding 35 gpm plus 10 gpm from the Southeast Sub-Mains. In 1998,
<br />excluding the inflows from 6-Right, a iota] of approximately 2,000 acres were affected, yielding an estimated 55
<br />gpm plus 10 gpm from the Southeast Sub-Mains, which are located in the EMD. All dust control water that from
<br />the active longwall and continuous miner equipment, plus all inflows to the EMD, excluding the 6-Right inflow, are
<br />collected in a sump at 10-Right. The sump has been maintaining a constant pool level by pumping at
<br />approximately 170 gpm since 1998. The estimated inflows to this area are 65 gpm from groundwater, and 111 gpm
<br />from the equipment, for a total of 176 gpm. Since there is a close match between these two figures, the EMD
<br />portion of the water balance appears to be reasonable.
<br />Some evaporation of mine inflow water occurs, but has not been quantified. Evaporation is limited due to the lower
<br />temperature of mine inflows, moderate temperatures within the mine, relatively high mine humidity, and the fact
<br />that mine water storage is limited to sealed mine areas. Therefore, minor evaporative losses are not considered in
<br />the water balance calculations, as they relate to the need for any mine discharge to receiving streams.
<br />•
<br />Since all mine inflow figures used in the water balance are measured flows or based upon measure flows, any
<br />minor evaporative losses do not affect the net calculated water volumes routed to storage or dischazged.
<br />PR06-07 2.05-137 11/07/06
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