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• 91M001 and 91M004. During the 1999 Water Year, well 91M001 showed a seasonal Fluctuation level but <br />appears to be stabilizing. A similar pattern was noted at well 91 M004, however, the rates of change were much <br />less pronounced. Water levels at the Ashley well (Figure 41) dropped appreciably after subsidence but are now <br />recovering rapidly. <br />ALLUVIAL GROUNDWATER MONITORING <br />Alluvial deposits containing groundwater are monitored in [he Foidel Creek, Fish Creek, Trout Creek and Middle <br />Creek drainages. In the Foidel Creek drainage, sites both upstream and downstream of the TCC portals and <br />support facilities are monitored. In [he Fish Creek Drainage, sites upstream and downstream of the Mine 2 area <br />and the Fish Creek Borehole mine dewatering facilities are monitored. <br />Foidel Creek Alluvial Groundwater: During 1999, five Foidel Creek alluvial wells (009-S-10, 001-5-~, 008-AV- <br />2, FO-I, and FO-4) required monitoring for water levels and field parameters on a monthly basis, and water <br />quality sampling on a quarterly basis. An additional well (008-AV-I) required only monthly monitoring for <br />water levels and field parameters. All monitoring requirements were met at these sites. Tables 24 through 29 <br />provide summaries of the 1999 Water Year data collected at each site. Tables 24a through 29a provide period of <br />record statistical summaries of collected data at each site. Figures 43 through 55 provide graphical <br />representations ofwater levels and selected water quality parameters recorded a[ each site. <br />• <br />Water levels during 1999 remained generally consistent with established ranges and patterns and showed the <br />typical seasonal variability of elevated water levels in the spring. Well 009-S-10 provides data for the alluvial <br />aquifer upgradient front the mine portals. Well 001-5-~ is located just downgradient form the mine portals and <br />surface facilities location and is monitored in conjunction with surface water monitoring site 8. Figure 47 is <br />indicative of the general relationship between the alluvial groundwater elevations and surface water elevations at <br />these nvo sites. Wells 008-AV-I and 008-AV-2 are monitored in conjunction with surface water site 304 at a <br />point on Foidel Creek approximately 1000 feet upstream of the confluence of Foidel and Middle Creeks. Water <br />levels in these wells and the stream show the typical seasonal interrelationship of relatively rapid increases and <br />declines associated with spring runoff (Figure 48). The longer-term trends in water levels at these sites generally <br />parallel the fluctuations observed in annual stream flows. Wells FO-I and FO-4 are situated on Foidel Creek <br />approximately overlying the gateroads between [he second and third panels be mined in the EMD. Typical <br />seasonal Fluctuations in water levels are depicted at these sites on figures ~2 and 54. <br />Field conductivity measurements in general at +vell 001-5-5 (1999 average 2040) were again noted to be Itiglter <br />than the upgradient site 009-5-10 (1999 average 1275). Moving downgradient, field conductivities a[ wells FO-4 <br />and FO-1 averaged 212 and 215 respectively based on the 1999 data. Further downgradient, field <br />conductivities at well 008-AV-2 are averaging 1340. Conductivity values at well 009-S-10 Fluctuated within <br />previously established ranges during 1999. Thz generally increasing field conductivity trend noted in previous <br />• years for well 001-5-~ appears to be continuing to level off in the 1999 data. Field conductivity measurements at <br />wells 008-AV-1 and 008-AV-3 are comparable to measurements at well 001-S-5 and occurred within previously <br />-5 <br />