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<br />GROUND WATER MONITORING <br />BEDROCK <br />The Wadge Overburden formation (including the Wadge coal seam) overlies the Trout Creek <br />Sandstone and underlies the Twentymile Sandstone. Four wells in the Wadge Overburden <br />(which includes the Wadge Coal) are monitored in the vicinity of Mines No.1 and Eckman Park. <br />Wells 009-79-4, 006-82-74C, 94M001, and 94M002 require semi-annual monitoring for water <br />levels, field parameters, and water quality samples. Required monitoring for these wells was <br />completed in 1997 with field measurements obtained and water quality samples collected <br />during May, and September. Beginning in 1995, monitoring wells 026-79-4 and 026-79-6 were <br />replaced by 94M001 and 94M002. <br />Tables 4 through 7 provide summaries of the 1997 Water Year data collected at each site. <br />Tables 4a through 7a provide period of record statistical summaries of collected data at each <br />site. Tables 4b through 7b provide period of record water level summaries for each site. <br />Figures 4 through 11 provide graphical representations of water levels TDS concentrations <br />recorded at each site. <br />The potentiometric surface in the Wadge Overburden is generally observed to slope from <br />south to north in monitored wells in the vicinity of Mine 1 and Eckman Park as shown by water <br />levels in wells 009-79-4, 006-82-74C, 94M001, and 94M002. During 1997, water levels in well <br />006-82-74C (Figure 4) displayed a slightly increasing trend with a pronounced seasonal <br />fluctuation. Wells 009-79-4 (Figure 6), 94M001 (Figure 8), and Well 94M002 continued to <br />show a steady water level, and returned values consistent with previous data. <br />The water quality data for the Mine No. 1 Wadge Overburden wells are summarized on Tables <br />4 through 7. Plots of dissolved solids concentrations are presented on Figures 5, 7, 9, and 11. <br />The baseline water quality of the Wadge overburden is a mixed type water with a dissolved <br />solids level ranging from 500 mg/I to 3500 mg/L. Elevated dissolved solids levels in wells 006- <br />82-74C and 009-79-4 appears to correlate somewhat with seasonal recharges from the spoil <br />aquifer following backfilling and reclamation, indicating that they are affected by seepage from <br />the spoils aquifer. Wells showing elevated dissolved solids tend to also have elevated sulfate, <br />calcium and magnesium and reduced SAR compared with undisturbed Wadge Overburden <br />groundwater chemistry. This is consistent with mixing with spoil waters which are typically <br />characterized by elevated dissolved solids, sulfate, calcium and magnesium as discussed <br />below. Well 009-79-4 and 006-79-4 dissolved solids in 1997 continue to be more typical of <br />the normal levels recorded for this site following higher levels recorded in 1995. TDS levels in <br />wells 94M001 and 94M002 are noted to be significantly lower than those recorded in wells <br />006-82-74C and 009-79-4. The data does not indicate any significant changes in the trace <br />metals concentrations. <br />No anomalous water quality impacts attributable to mining were evident in data collected from <br />Wadge Overburden wells during 1997. At wells 94M001 (Table 6) and 94M002 (Table 7), <br />several parameters returned values outside of previously established ranges for these sites. <br />While database for these sites is limited and typical ranges are still being established, values <br />returned support the observations noted above. No significant deviations were noted however. <br /> <br />EP97TEXT.DOC 07/01/98 <br />