2008-06-27_REPORT - C1980007 (4)

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West Elk Mine 2007 Annual Hydrology Report 45 • The casings in several monitoring wells have collapsed in the past several years and are likely the result of mining-induced subsidence. These wells include SOM-45-H-1 (Sept. 2002), SOM-2-H (Jul. 1999), SOM-16-H (Sep. 2000), 96-27-1 (Apr. 2002), SO.W-1 (Jun. 2002). Well 23-H-1 (Aug. 2006) has obstructed and damaged casing resulting from poor installation procedures, not related to mining activities. As a result, hydrologic data from these damaged wells for WY 2006 and WY 2007 are not available. SOM 13 has recently become obstructed, therefore, hydrologic data is not available for this site for WY 2007. 5.4.1 Impacts to Ground Water Quantity and Quality In general, there were no significant water quality changes in the ground water monitoring wells during WY 2007 (Appendix G). However, in WY 2007 there were several minor changes noted in the Upper Dry Fork Alluvial Well, Lower Dry Fork Alluvial Well, SOM 45-H-2, SOM 80, SOM C-76, SOM 23-H-4, SOM 23-H-3, SOM 23-H-2, 03-11-1, SOM 3E, 96-2-2, RAV 413, SOM 129- H, 1-11-01, and SOM-313. The holding time was exceeded for the initial sample collected in August 2007 for Well 03-I1-1 because of a UPS delivery mistake, so a duplicate sample was collected and analyzed in October 2007. As noted above, no water quality or water level data are available for WY 2007 for the seven damaged monitoring wells (SOM-45-H-1, SOM-2-H, SOM- 16-H, 96-27-1, SOW-1, SOM-13 and SOM-23-H-1). The Upper Dry Fork Alluvial well had a slightly elevated conductivity of 577 [mhos/cm compared to the maximum baseline value of 509 gmhos/cm. Lower Dry Fork Alluvial Well had slightly elevated conductivity of 514 gmhos/cm compared to the maximum baseline value of 497 gmhos/cm, elevated levels of total iron of 1.15 mg/1 compared to the maximum baseline of 0.51 mg/1, elevated dissolved arsenic of 0.0032 mg/1 compared to the maximum baseline of 0.0004 mg/1, slightly elevated pH of 8.1 s.u. compared to the maximum baseline of 8.0 s.u Well SOM 80 had an elevated conductivity of 1,150 gmhos/cm compared to the maximum baseline value of 897 gmhos/cm. SOM 13 has an obstruction, therefore, no water quality data are available for this site for WY 2007. Well SOM 45-H-2 has a slightly elevated pH of 8.6 s.u. compared to the maximum baseline of 8.2 s.u. Well SOM 23-H-4 had a slightly elevated dissolved boron level of 0.33 mg/1 compared to the maximum baseline value of 0.30 mg/1, slightly elevated total iron of 2.00 mg/1 compared to the maximum baseline value of 1.75 mg/1, slightly elevated dissolved lead of 0.0025 mg/1 compared to the maximum baseline value of 0.0017 mg/1, and slightly elevated sodium of 519 mg/1 compared to the maximum baseline value of 487 mg/1. Well SOM 23-H-3 had slightly • elevated phosphate of 0.40 mg/1 compared to the maximum baseline value of 0.24 mg/1 and elevated zinc of 0.08 mg/1 compared to the maximum baseline of 0.04 mg/1. The holding time was June 2008 HydroGeo, Inc.