2015-04-06_REPORT - C1981022 - Laserfiche WebLink

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elevation 6014 feet in 1990. Water levels then recovered, with an increase to elevation 6033 feet in 1992, and rising to elevation 6051 feet in 1993. The water level ranged from 6038 feet to 6048 feet in 1994 and 1995, and then rose to elevation 6054 feet in 1997. In 1998 the water level ranged between 6052 and 6053 feet in elevation. Similar to monitoring well H -10, since October 1999 and during 2000 through 2004 no water was measured in well B -6. The lack of water in the H -10 and B -6 wells may be due to a blockage or another problem in the wells. The scenario that both wells failed at the same time appears, however, unlikely. Performance and condition of the bailer when raised during sampling do not suggest the wells were blocked. A more plausible explanation is that because these two wells are located in two different drainages and both are dry suggests that the water level, thus inflow, into the abandoned Somerset Mine has simply decreased for some unknown reason. Curiously, this decrease is coincident with the time of the mine fire event and pumping from the North Fork into the Sanborn Creek Mine. Flows also ceased just a few months earlier from Spring 8 (believed to have been from the old Oliver Mine D -seam workings). However, unlike the Oliver Mine, there is no portion of the abandoned B- and C -seam workings of the Somerset Mine that overlie the Sanborn Creek Mine. Rather, there is more than 200 horizontal feet of unmined B -seam coal barrier pillar separating and isolating the Somerset Mine B workings from the Sanborn Creek mine B workings. OMLLC has held the belief through the years that should wells H -10 and B -6 continue to remain dry, the data supports the conclusion that the Somerset mine will continue to have a negligible affect on the hydrologic balance of the region. (See the following discussion regarding the D213 water transfer well for additional ground water discussions.) In the fall of 2004, the Elk Creek Mine D seam development was to have intercepted the vicinity of the B -6 well. Because of the MSHA requirement to seal interconnecting mine openings in order to isolate mine atmospheres, the B -6 well was plugged with concrete on October 19, 2004. Upon entering the vicinity of the well, the steel casing was never actually encountered by the D seam continuous miner section and the casing remains intact within a coal pillar." BC -1 Well — Lower Bear Creek Canyon — Alluvium/Colluvium The Bear Creek canyon light use road is used extensively to access the upper reaches of Bear Creek for cattle and sheep grazing, logging, gas company access, mine exploration and methane ventilation activities, hunting, etc. The two track, ranch road crosses Oxbow, BLM, other private lands. The BC -1 Well is located in the shallow alluvium/colluvium located near the entrance to Bear Creek canyon in the vicinity of the railroad trestle. The purpose of the well is to monitor possible groundwater changes down gradient from the Elk Creek Mine D seam mining activities in the Bear Creek drainage area. In addition, it is important to note that the BC -1 well is also located down - gradient from the old Somerset Mine workings as well. 13