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• level tape could be dropped drown for a second semi-annual water level reading, however there was not adequate access to obtain a water sample for measuring conductivity and pH. 3.2 Alluvial Groundwater Monitorine Alluvial ground water in the Twentymile Park Basin exists under unconfined conditions within the alluvial materials underlying the major surface drainages of the area and backfilled areas of adjacent surface mined aeeas. Stream flows aze the primary source of rechazge to the alluvial aquifers. Alluvial deposition is limited in areas where stream gradients are relatively steep and in areas where the stream channel has eroded to or intersects resistant bedrock. Consequently, the alluvial deposits do not tend to be continuous. Shallow wells completed in these deposits indicate that they are usually less than 20 feet thick and the depth to ground water is typically less than 10 feet. The limited extent of the Foidel Creek alluvial deposits, and the lack of base flow in the creek indicates that these deposits are relatively insignificant to the area ground water hydrologic system. Alluvial deposits containing groundwater are monitored in the Foidel Creek, Fish Creek, Trout Creek and Middle Creek drainages. In the Foidel Creek drainage, sites both upstream and downstream of the TCC portals and support facilities are monitored. In the Fish Creek Drainage, sites upstream and downstream of the Mine 2 area and the Fish Creek Borehole mine dewatering facilities aze monitored. Foidel Creek Alluvial Groundwater: During 2002, five Foidel Creek alluvial wells, 009-5-10, 001-5-5, 008- AV-2, FO-1, and FO-4, required monitoring for water levels and field parameters on a monthly basis, and water quality sampling on a quarterly basis. An additional well, 008-AV-1 required monthly monitoring only for water levels and field parameters. All monitoring requirements were met at these sites. Tables 24 through 29 provide summaries of the 2002 Water Yeaz data collected at each site. Tables 24a through 29a provide period of record statistical summaries of collected data at each site. Figures 43 through 55 provide graphical representations of water levels and selected water quality parameters recorded at each site. Water levels during 2002 remained generally consistent with established ranges and patterns and showed the typical seasonal variability of elevated water levels in the spring. Well 009-5-10 provides data for the alluvial aquifer upgradient from the mine portals. Well 001-5-5 is Located just downgradient from the mine portals and surface facilities location, and is monitored in conjunction with surface water monitoring site 8. Figure 47 is indicative of the general relationship between the alluvial groundwater elevations and surface water elevations at these two sites. Site 8 exhibited a drop in water levels in 2001, which appears to have stabilized in 2002. Well 001-S-5 also exhibited a drop in water level in 2001, a few months after that of site 8, but recovered shortly thereafter. In 2002, water levels at site 8 appeaz consistent with levels seen in 2001. Wells 008-AV-I and 008- AV-2 are monitored in conjunction with surface water site 304 at a point on Foidel Creek approximately 1000 feet upstream of the confluence of Foidel and Middle Creeks. Water levels in these wells and the stream show the typical seasonal interrelationship of relatively rapid increases and declines associated with spring runoff (Figure 48). The longer-term trends in water levels at these sites generally parallel the fluctuations observed in . annual stream flows. Wells FO-1 and FO-4 are situated on Foidel Creek approximately overlying the gateroads between the 8 Rt and 9 Rt longwall panels in the EMD. Typical seasonal fluctuations in water levels aze depicted at these sites on figures 52 and 54. 7