2010-06-04_PERMIT FILE - C1982056A (8)

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Areas of spoil, waste, non -coal waste disposal, water handling and treatment facilities, embankments, and impoundments are shown on Map 24, Surface Facilities, and Map 26, Fish Creek Borehole /Shaft Area Facilities and • Access Road. Elevations and locations of test borings and core samplings are shown on Map 12, Sample Locations. One oil and gas well exists within the permit boundary for the SWMD. The well was drilled during 1975, and originally was completed as an oil well. However, the yield was insufficient and the well was converted to a gas well. The well is approximately 7,500 feet in depth and its location is shown on Map 23. TCC acquired ownership of the well in 1993. The well was plugged by placing a cement plug in the well. All of the designated mining areas (SWMD, EMD, NMD, and WMD) are located within the Twentymile Park Basin, which is formed by the locally significant Twentymile Park Syncline. This syncline and associated anticlinal structures form an enclosed ground water basin, which is rimmed by outcrops of the major water - bearing units described in Section 2.04.6, Geology Description. The limits of potential mining- related impacts on the ground water hydrologic system are shown on Map 4, Proposed Hydrologic Area Boundaries. BEDROCK AQUIFER SYSTEM Twentymile Sandstone Aquifer Aquifer characteristics of the Twentymile Sandstone have been measured within the permit area in six wells, and the results for transmissivity are reported in a range of 0.25 to 32 ft /day (Applied Hydrology Associates, 1984). Water levels of the Twentymile Sandstone have been monitored in the mine plan area in Wells 006 - BRDH -7, 006- 82 -48A, FBR -11 -B, FBR -12 -A, FBR -9 & 10, and FBR -2. Recharge, discharge, ground water movement, and water quality in the Twentymile Sandstone are discussed later in this section. The potentiometric surface map for the Twentymile Sandstone is presented as Figure 6R. • Trout Creek Sandstone Aquifer Recharge to the Trout Creek Sandstone occurs along the unit outcrop, as shown on the Twentymile Sandstone Potentiometric Surface Map (Figure 6R). There is very limited hydrologic connection between the Trout Creek Sandstone and the Wadge Coal Seam, which could effect the proposed mining operations. Results of monitoring in the current mining area indicated that vertical hydrologic communication between major aquifers along the fault zones is very limited or non - existent. Wadge Overburden Aquifer Field data from ground water monitoring wells was used to construct a potentiometric contour map for the Wadge Overburden aquifer in the permit area. This was developed by using water level data from 1983, prior to the start of underground mining in the eastern portion of the study area, and recent data (1993) from the western sector, as presented by Figure 6S. This figure was updated following completion of the installation and monitoring of additional monitoring wells. The potentiometric map for the Wadge Overburden aquifer was constructed using only water level data, which were deemed to be reliable. Data from the new wells was used to check and update the referenced figures. Additionally, TDS contours have been added to the figures; which have been moved to Exhibit 11D. Figure 6S has been retained in the PAP to provide historic perspective. Exhibit 11D indicates a TDS plume extending into the Eastern Mining District. The highest TDS concentration is to the southwest, in the vicinity of the adjacent surface mine, and diminishes to the northeast. • PR09 -08 2.04 -41 09/15/09