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Permit C-81-071 1994 Annual Hydrology Report GROUND WATER MONITORING BEDROCK Four wells in the Wadge Overburden (which includes the Wadge Coal) are monitored. The wells are in the vicinity of Mines No.1 and Eckman Park. In 1994 wells 026-79-4 and 026-79-6 were replaced by 026-M94-001 and 026-M94-002. Water Levels Water levels in the toe of the Mine No. I Wadge Overburden wells have been measured since 1979 (Figure 4). Only one water level has been measured in the new wells. The water levels generally dropped when strip mining occurs nearby, but recovered when the area is backfilled. The data indicates that the water levels in the Wadge overburden vary a small amount seasonally, with levels typically rising following spring snowmelt and recharge and then declining through the summer, fall and winter. Water Quality The water quality data for the Mine No. 1 Wadge Overburden wells are summarized on Tables 4 through 9. A plot of dissolved solids is presented on Figure 7. The baseline water quality of the Wadge overburden is characterized by asodium-bicarbonate type water with a dissolved • solids level of approximately 1000 mg/I. Elevated dissolved solids levels in well 009-74-4, 026- 79-4 and 006-82-74C appears to coincide with water level recovery following backfilling and reclamation, indicating that they are affected by seepage from the spoils aquifer. Wells showing elevated dissolved solids tend to also have elevated sulfate, calcium and magnesium and reduced SAR compared with undisturbed Wadge Overburden groundwater chemistry. Thi is consistent with mixing with spoils water which are characterized by elevated dissolved solids sulfate, calcium and magnesium as discussed below. The data does not indicate any significant changes in the trace metals concentrations. ALLUVIUM s Alluvial sediments are monitored in the Foidel creek valley upstream and downstream of Mines 1 and in the Fish Creek valley upstream and downstream of Mine 2. Four wells completed in the Foidel Creek alluvium are monitored. Three wells completed in the Fish Creek alluvium are monitored. Water levels The plots of the historic water levels in the four Foidel Creek alluvial wells are presented on Figures 8 and 10. The plots of the historic water levels in the Fish Creek wells are presented on Figures 11 through 13. The water levels in the adjacent streams show the typical seasonal . pattern of relatively rapid increase and decline due to spring runoff. In addition they show the EP4TEXT DOC 07/17/97 Page 2