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a total of 176 gpm. Since there was a close match between these two figures, the EMD portion of the water balance
<br />appeazed to be reasonable (1989-1998, Table E51-3; and future years (1999-2014), Tables E51-6 through E51-8).
<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. Since all mine inflow figures used in the water balance are
<br />measured flows or based upon measure flows, any minor evaporative losses do not affect the net calculated water
<br />volumes routed to storage or discharged (previous historical practice).
<br />Based on the 2002 water balance the estimated Fish Creek Borehole pool volume was approximately 546,000,000
<br />gallons (Exhibit 51, Table E51-3). At the end of the water yeaz 1998, the elevation in the FCB pool was 5,882 ft.
<br />At this elevation, approximately 18,000,000 ftz of workings were flooded. Based on an average height of 8.5 ft and
<br />an extraction rate of 74 percent within the panel area, the initial void space for the flooded mine workings is
<br />calculated at 850,000,000 gallons. Since air pockets developed in the mine voids and gob, and the gob does not
<br />saturate immediately, the inflow estimates, and 2002 water balance estimate of 546,000,000 gallons appeared
<br />reasonable.
<br />Increased water use by the longwall system installed in 2006, and improved mine water recycling have resulted in a
<br />simplified mine water balance, as shown by Table E51-25. With elimination of mine water dischazge, any
<br />difference between system inputs and outputs results in a corresponding increase or decrease in mine water storage
<br />levels. With a maximum anticipated annual variance of 232.0 acre-ft (storage increase), available mine water
<br />storage capacity is more than adequate to handle anticipated storage needs.
<br />Water Handline: Presently, the mine can handle mine water inflows in four ways: 1) Discharge to Fish Creek; 2)
<br />Discharge to Foidel Creek; 3) Transfer to the Million-Gallon Tank; 4) Transfer to the underground storage pool
<br />below the FCB or the 10-Right storage pool; or 5) Recycle to the Prep Plant as make-up water. All water except
<br />the ground water inflow to the SMD, can be directed to Foidel Creek via site 109 by diverting underground
<br />dewatering discharge using existing piping. In May 1999, a system to recirculate water pumped out of the mine via
<br />Site 109 was completed. This allows for water recovered from the mine to be reused for water sprays and cooling.
<br />Water that is captured in the mine can be directed in a number of directions. The water from the 10-Right borehole
<br />can either be directed up the North Mains to Site 109 or can be dischazged behind the seals in the southern portion
<br />of the EMD, where it can be discharged to Fish Creek via Site 115. The water from the 6-Right area can either be
<br />directed up the North Mains to Site 109 or can be discharged behind the seals into the SMD where it will report to
<br />the Fish Creek Borehole sump. From Site 109, the water can be directed to Site 114, Pond D for discharge into
<br />Foidel Creek, to the Million-Gallon Storage Tank, or to the Area 1 Pit and then pumped directly into Foidel Creek
<br />without being routed through Pond D.
<br />As of August 2006, the FCB pool had an elevation of 5,947 feet. The pool cannot be allowed to exceed 5,950 feet
<br />because it would then overflow against the seals in the SMD. In order to provide a margin of safety, the pool is
<br />now being pumped continuously to maintain the current level. This has required a reduction of approximately 50
<br />percent or 273,000,000 gallons in the underground water storage capacity. In order to compensate for this storage
<br />loss, TCC developed and permitted a second ground water storage area below the 10-Right Shaft with a capacity of
<br />approximately 2,671,800,000 gallons at a maximum elevation of 5,916. This water, plus inflow to the pool will
<br />have to be pumped from the FCB. The timing and water quality issues related to this dischazge are discussed in
<br />"Effects on Ground Water Quality of Aquifers and Surface Water Systems Impacts of Mine Water Discharge"
<br />below.
<br />Dewaterin2 and Potentiometric Drawdown in Bedrock Units
<br />The projected inflows to the mine from the Wadge overburden unit will cause dewatering and potentiometric
<br />drawdown in the unit. Where the Twentymile Sandstone directly overlies the mine workings, it will also be
<br />affected. In fourteen years of mining, no impact to the Trout Creek Sandstone has been observed, and water quality
<br />data from the mine inflow does not indicate any significant connection to either the overlying Twentymile
<br />Sandstone or the underlying Trout Creek Sandstone. Well 006-82-48A, completed in the Twentymile Sandstone,
<br />showed a rapid water level decline before being rendered inoperable due to being undermined by a longwall pane].
<br />TR07-59 2.05 - 138 04/02/07
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