2009-02-20_REPORT - C1980001 (4)

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the Trout Creek Sandstone aquifer. To date, no impacts from mining activity are evident in Well TCS-1. TCS-1 was not sampled in 2004 due to equipment problems. The demolition of an adjacent house removed power from the site. During demolition the well sustained damage. Sampling was attempted using a generator but the well was deemed not functional. TCS-1 was refurbished in the fall of 2005 and sampled thereafter. Ground water sampling is performed in accordance with EPA approved methods and instrumentation. The ground water quality at the Edna Mine is monitored via the parameters, locations and frequency listed in Table 4.6-54, Section 4.6.8.4 of the permit. Analyses results for monitoring wells TR-1.5, TR-3, TR-4, WR-1 and TCS-1 are found in Tables 8, 9, 10, 11 and 12. Results of the analyses are discussed below. 4.2.1 Ground Water Temperature Chart 22 shows temperature values for monitoring wells TR-1.5, TR-3, TR-4, WR-1 and TCS-1 for the period of record. Temperature exhibited the same trends in 2008 as found during baseline studies and previous years monitoring. Specifically, patterns in temperature are seasonal, warming until July or August and than cooling throughout the remaining sampling season. The amount of temperature fluctuation in Well TR-4 has been historically somewhat greater than expected suggesting the flow to the perched aquifer, although subsurface, is very shallow. The lowest temperature in 2008 was recorded at monitoring well TR-1.5 in October with a reading of 6.6 °C and the high was recorded at monitoring site TR-4 in August with a reading of 15.1 °C. 4.2.2 Ground Water pH Chart 23 shows pH concentrations for monitoring wells TR-1.5, TR-3, TR-4, WR-1 and TCS- 1 for the period of record. Values of pH during 2008 remained relatively constant over the monitoring period. There is no apparent trend regarding pH. Overall, the groundwater has tended to be alkaline throughout the period of record. The lowest pH value in 2008 was recorded at monitoring well TR-1.5 in October with a reading of 6.75 standard units and the high was recorded at monitoring well TR-3 in May with a reading of 7.94 standard units. 4.2.3 Ground Water Specific Conductivity and Total Dissolved Solids Charts 24 and 25 show specific conductivity and TDS concentrations for monitoring wells TR-1.5, TR-3, TR-4, WR-1 and TCS-1 for the period of record. Specific conductivity and TDS values for the three alluvial wells have remained fairly constant over the majority of the period of record. While specific conductivity and TDS values at sites TR-3 and TR-4 are consistent with values obtained during the baseline studies, these parameters and several others have elevated rapidly and remained elevated at TR-1.5 since 1995. The source of the elevated values is not readily identifiable. A few factors which may have contributed to the elevated values were mentioned in the 1996 Report (i.e., inundation of the area in late spring of 1995 and the laying of telephone cable immediately upstream of the area during the summer of 1995). If the elevated values resulted from those activities, the values should have 10