2010-02-19_REPORT - C1980001 (4)

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4.0 GROUND WATER As previously mentioned, ground water is monitored for water quality and static water level elevations at monitoring wells TR-1.5; TR-3, TR-4, WR-1 and TCS-1. The following section discusses quality and static water level elevations of ground water at the Edna Mine. 4.1 Ground Water Elevations Water levels in the alluvial wells at the Edna Mine have remained constant over the period of record with minor fluctuations occurring seasonally. Elevations of the static water level in the alluvial wells (TR-1.5, TR-3 and TR-4) and the West Ridge spoils well ('R-1) are shown in Chart 21. In reviewing the data, it is apparent that WR-1 has reached steady state and exhibits consistent seasonal fluctuations. The seasonal fluctuations result from spring snowmelt causing a mounding of water in the perched aquifer which drains over the summer via discharge from a spring on the lower portion of West Ridge near the elevation of Trout Creek. Monitoring Well TR-4 was broken off and plugged by livestock in July 2002, preventing monitoring for the remainder of 2002. The well was repaired in the spring, of 2003. Ground water wells TR-1.5, TR-3, TR-4 and WR-1 all maintained levels and trends, a slight decrease of water level during the annual sampling season, similar to historical data during 2009. Ground water well elevations are provided in tabular format in Table 7. 4.2 Ground Water Quality ' Comparisons of water quality data gathered from the alluvial wells at the Edna Mine must be exercised with caution due to the differing stratigraphic units intersected along Trout Creek adjacent to the various wells. The alluvium in the vicinity of Well TR-1.5 intersects stratigraphy ' above the Wadge coal seam while the alluvium in the vicinity of TR-3 intersects stratigraphy below the Wadge coal seam. Alluvium in the vicinity of TR-4 intersects even lower stratigraphic units than those at TR-3. The influence from contact with the differing lithology can not be ' quantified; therefore, differences between the wells may not be responses to mining related activities. ' As previously mentioned, TR-4 was repaired in 2003. Groundwater samples from TR-4 show an increase in several parameters directly after repair, some of which have begun to stabilize and decrease to historical levels. Prior to 2003, parameters at the well had stabilized. Therefore, it is assumed that this increase is due to the well repairs. ' Monitoring of Well TCS-1 was initiated in 1995 to ensure the absence of mining impacts on 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. ??I-?YwclE.......G Page I I