|
Inflows to the EMD were estimated from the areas inined and the actual inflow measured. In 1995,
<br />approximately 200 acres were affected by longwall mining, yielding an estimated 5 gpm. Some fault inflows
<br />were encountered at the end of the water year. In 1996, approximately 800 acres in the EMD were affected by
<br />mining, yielding approximately 20 gpm, including the fault inflows. In 1997, excluding the inflows from 6-
<br />Right, a total of approximately 1,400 acres were affected, yielding 35 gpm plus 10 gpm from the Southeast Sub -
<br />Mains. In 1998, excluding the inflows from 6- Right, a total of approximately 2,000 acres were affected,
<br />yielding an estimated 55 gpm plus 10 gpm from the Southeast Sub- Mains, which are located in the EMD. All
<br />dust control water from the active longwall and continuous miner equipment, plus all inflows to the EMD,
<br />excluding the 6 -Right inflow, are collected in a sump at 10- Right. A constant pool level was maintained in the
<br />sump by pumping at approximately 170 gpm. The estimated inflows to this area are 65 gpm from groundwater,
<br />and 111 gpm from the equipment, for a total of 176 gpm. Since there was a close match between these two
<br />figures, the EMD portion of the water balance appeared to be reasonable (1989 -1998, Table E51 -3; and future
<br />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
<br />lower temperature of mine inflows, moderate temperatures within the mine, relatively high mine humidity, and
<br />the fact that mine water storage is limited to sealed mine areas. Since all mine inflow figures used in the water
<br />balance are measured flows or based on measure flows, any minor evaporative lasses do not affect the net
<br />calculated water 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
<br />546,000,000 gallons (1,675 acre -ft, Exhibit 51, Table E51 -3). At the end of the water year 1998, the elevation in
<br />the FCB pool was 5,882 ft. At this elevation, approximately 18,000,000 ft2 of workings were flooded. Based on
<br />an average height of 8.5 ft and an extraction rate of 74 percent within the panel area, the initial void space for
<br />the flooded mine workings is calculated at 850,000,000 gallons (2,610 acre -ft). Since air pockets developed in
<br />the mine voids and gob, and the gob does not saturate immediately, the inflow estimates, and 2002 water
<br />balance estimate of 546,000,000 gallons appeared reasonable.
<br />Increased water use by the longwall system installed in 2006, and improved mine water recycling have resulted
<br />in a simplified mine water balance, as shown by Table E51 -25. With reduction of mine water discharge, any
<br />difference between system inputs and outputs, with an appropriate adjustment for any discharge, results in a
<br />corresponding increase or decrease in mine water storage levels. With a maximum anticipated annual variance
<br />of 323.7 acre -ft (storage increase), periodic discharge may be necessary to maintain adequate freeboard in sealed
<br />mine areas, although available mine water storage capacity should generally be adequate to handle anticipated
<br />storage needs.
<br />Water Handling: Presently, the mine can handle mine water inflows in several ways: 1) Transfer to the
<br />underground storage pool below the FCB or the 10 -Right storage pool; 2) Discharge to Fish Creek via Site 115;
<br />3) Discharge to Foidel Creek via Site 109; 4) Transfer to the 6MN Mine Water Storage Reservoir and 6MN
<br />Million - Gallon Tank; 5) Transfer to the Barricade Chamber; 6) Transfer to the Area 1 Pit; and /or 7) Transfer to
<br />the Million - Gallon Tank. Water routed to the 6MN Mine Water Storage Reservoir and 6MN Million - Gallon
<br />Tank, the Barricade Chamber, the Area 1 Pit, or the Million - Gallon Tank, can be recycled to the mine for mine
<br />use. Water from the Area 1 Pit and Million- Gallon Tank can also be transferred to the Washplant.
<br />Water that is captured in the mine can be directed in a number of directions. Water from the EMD and the 10-
<br />Right boreholes can be directed to the 6MN Storage Reservoir; to the Barricade Chamber, then up the North
<br />Mains to the Area 1 Pit; to the Area 1 Pit via the overland pipeline; or can be discharged to Foidel Creek at Site
<br />109/114. Water from the NMD area can be directed up the North Mains to the Area 1 Pit; discharged behind the
<br />seals into either the EMD (see above) or the SWMD, where it will report to the Fish Creek Borehole sump, and
<br />can be transferred to the Barricade Chamber, the Area 1 Pit, or discharged to Fish Creek at Site 115. Water
<br />from the WMD can be directed up the North Mains to the Area 1 Pit; discharged behind the seals into the
<br />SV;MD, where it will report to the Fish Creek Borehole sump, and can be transferred to the Barricade Chamber,
<br />the Area I Pit, or discharged to Fish Creek at Site 115.
<br />TR1.3 -83 2.05 -138 11/03/14
<br />
|