2009-07-01_REPORT - C1980007 (6)

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West Elk Mine 2008 Annual Hydrology Report 71 0 7.0 SUMMARY During WY 2008, all aspects of the hydrologic monitoring program were conducted in accordance with all permit commitments. Based on the surface water, ground water, spring and seep, underdrain, and mine inflow monitoring data collected to date, MCC's mining operations did not cause any significant long-term adverse impacts to local surface or ground water resources in WY 2008. Since MCC's mining operations have shifted from the west and east sides of the permit area to the south side, MCC's hydrologic monitoring program was revised accordingly. The current hydrologic monitoring plan was proposed as part of the South of the Divide PR-10 application. This plan was approved by the CDRMS in June 2006 and was initially implemented in WY 2007. A multi-year drought was abated with below but near normal precipitation in WY 2003 and WY 2004. Continued improvements in climatic conditions in WY 2005 through WY 2007 resulted in slightly below to near average precipitation which gave rise to slightly below to near average flows in area streams. Precipitation was near or above normal in the permit and surrounding area in WY 2008, resulting in near average to above average stream flows. Spring flows in the permit and surrounding area in WY 2008 were generally high compared to recent years. Maximum spring and seep flows in WY 2008 were the highest recorded to date at 18 of the 36 monitored springs and average annual spring and seep flows were higher in WY 2008 than in WY 2007 at 27 springs. The static water levels in most of the ground water monitoring wells have remained relatively constant over time, in some cases showing only seasonal variations. However, monitoring wells located above or down-gradient of active longwall mining operations often show lowered water levels. Since mining commenced in the Box Canyon Panel area (2001-2002) water levels in monitoring wells 1-11-01 and RAV-4b, both located down-gradient of active mining, have dropped a maximum of about 127 feet (April and May 2007) and 274 feet (April 2007), respectively, most likely the result of dewatering of the B-Seam. The water level in Well 01-I 1-I rebounded in WY 2008 and was 355.3 feet in May 2008 and 355 feet in June and August 2008, corresponding to an average rise of about 32 feet from WY 2007. The water level in RAV-4b rebounded slightly in WY 2008 and levels ranged from 618.7 feet (August 2008) to 619.0 fee (May 2008), corresponding to an average rise of about 7 feet from WY 2007. The well casings have collapsed or become obstructed in eight ground water monitoring wells. The obstruction/collapse are possibly due to mine-induced subsidence at well SOM-45-H1 (Sept. 2002), SOM-2-H (Jul. 1999), SOM-16-H (Sep. 2000), 96-27-1 (Apr. 2002), SO.W-1 (Jun. 2002), and SOM 13 (Jun. 2007). The collapsed casing in well SOM-23-H-1 (Aug. 2006) is most likely due to poor well construction. The casing has become obstructed in Well SOM 23-H-2 (August June 2009 HydroGeo, Inc.