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Evaporative loss will affect the total volume of water removed from the formatio Evaporation has previously
<br />been estimated to be approximately 8.6 acre-feet/yeaz per squaze mile mined, based upon measurements in the
<br />Belina Mine in Utah, and previously used for "Windy Gap" analyses for the Foidel Creek Mine. As of the end of
<br />.1998, approximately 5 squaze miles have been mined, however, most of the mined area was sealed shortly after
<br />completion of mining. ,Only the mains and a maximum of two longwall panels and associated headgate, tailgate,
<br />and bleeder entries aze open at any one time. This is equivalent df an azea of approximately 1.5 squaze miles.
<br />Using the previously estimated evaporation rate, and this azea yields an estimated evaporative loss from the
<br />formation of 13 acre-feeU~eaz (8gpm). Actual evaporative loss shbuld:be lower, because most of the azea in the
<br />longwall panels is either solid (pre-mining), or gob (post-mining) where ventilation is limited.
<br />Based on the 2002 water balance the estimated Fish Creek Borehole pool volume was approximately 546,000,000
<br />gallons (Exhibit 49, Table E49-3). .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 azea, 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 water balance estimate of 546,000,000 gallons appear reasonable.
<br />Water Handline: Presently,-the mine can handle mine water inflows in four ways: 1) Dischazge to Fish Creek; 2)
<br />Dischazge 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 dischazge 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 />It is anticipated that approximately 100 gpm can be recirculated. This will reduce future dischazges by the same
<br />amount.
<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 discharged behind the seals in the southern portion
<br />of the EMD, where it can be discharged to Fish Creek via Siie 115. The water from the 6-Right azea 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 dtrected to Site 114, Pond D for dischazge 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 can not 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 azea 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 aze discussed in
<br />"Effects on Ground Water Quality of Aquifers and Surface Water Systems Impacts of Mine Water Discharge"
<br />below.
<br />Dewaterina and PotenHometric 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 panel.
<br />~J
<br />PR06-07 2.05-138 11/07/06
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