2014-11-17_PERMIT FILE - C1982056A (2)

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Map 14, Wadge Seam Piezometric Contour Map (1999). In addition, locations of existing stream channels, impoundments, irrigation ditches, and drains are shown on Map 15, Alluvial Valley Floors and Water Rights. 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. TC 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, WMD and WCR) are located within the Twentymile Park Basin, which is formed by the locally significant Twentymile Park Syncline. This syncline and associated anticlinal structures form a closed 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 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 and Wolf Creek coal seams, which could affect 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, Wadge Seam, Wadae/Wolf Creek Interburden, and Wolf Creek Seam Aquifer Field data from ground water monitoring wells was used to construct potentiometric contour maps for the Wadge Overburden aquifer in the permit area. A map representing early conditions 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 installation and monitoring of additional monitoring wells. A map representing recent (2013) conditions was developed using monitoring data presented in the 2013 Annual Hydrology Report; that map is presented in Exhibit 9D. The potentiometric maps for the Wadge Overburden aquifer were constructed using only water level data from wells which were deemed to be reliable. As documented by previous studies (Robson and Stewart 1990), this geologic sequence, which forms the lower portion of the Williams Fork Formation, generally functions as a single hydrologic unit, so the Wadge Overburden may generally be considered representative of the unit. The exception should be noted, however, that the lower portions of the unit (Wadge/Wolf Creek Interburden and Wolf Creek Seam) are characterized by finer -grain structure and greater consolidation, so ground water occurrence and movement within the lower strata will be more limited than in the upper portions. 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. Characteristics of the overburden aquifer and Wadge /Wolf Creek Interburden, and Wolf Creek Seam Aquifer determined for specific monitoring wells in the permit and adjacent areas are summarized in Exhibits 9 and 9D, Aquifer Test Data. The highest hydraulic conductivity values for the overburden aquifer (0.4 to 0.86 ft/day) were calculated from pumping test data (Well FBR -1 and FBR -4). Pumped well data from Exhibit 9 indicate that the Wadge Overburden aquifer has an average permeability ranging from 0.11 to 0.32 ft/day, which is consistent with the low - yields observed in the monitoring wells. TR13 -83 2.04 -41 11/03/14