REP19597 - Laserfiche WebLink

Home Browse Search

Ron Thompson Page 2 01/17/01 Well Zone Distance from mined area 1995 1996 1997 1998 1999 NM-20 Ovbn 6000 ft 289 ft 342 ft 363 ft 350 ft 349 ft NM-21 Coal 4000 ft 796 ft N/A 762 ft 755 ft 740 ft NM-22 Ovbn 10,000 ft 317 ft 406 ft 440 ft 419 ft 414 ft SF-2 Ovbn 3000 ft 525 ft 653 ft 681 ft 677 ft 675 ft Although the rate of recovery is slow, data clearly indicates an increasing water level trend. Flooding of the workings is assumed to be underway as mine water discharge ceased in 1996. Inflows to the mine workings likely average about 130 gallons per minute (gpm). Data collected from the three GEM sites indicate that significant flooding north of Highway 12 has not reached GEM-2 well location at the former 3`~ North intake fan site. GEM-2 should be the first location to indicate flooding of the mine workings. Water levels remain essentially unchanged from the previous year. Analysis done by the Division estimated that a measurable water level will likely result at the GEM-2 and GEM-3 sites in May of the year 2000. Review of this analysis indicates this initial estimate may be premature by as much as two years. if flooding began at approximately the time the mine was sealed, it would take about 5.8 years before the area north of Highway 12 was flooded. Thus, GEM-2 may not measure water until approximately December 2001. GEM-1, at the old Jeffrey intake fan site near the mine portal, will be the last site to show flooding, although a small amount of flooding has occurred at this site due to it's location in the mains. Water measured at this site is probably spilling to the north into the extensive area of longwall mining north of Highway 12. GEM-1 is also the highest elevation of the mine floor of the three GEM wells that are completed in the workings. A water sample was obtained at this site in 1999. This water appears to be a sodium bicarbonate with a TDS of 1380 mg/I, which is normal for ground water in the area. Bedrock well water quality sampling requirements were dropped from the monitoring program due to the distance from the mined area. Previous sampling had indicated an improvement in salinity due to gradient reversal caused by mining drawdown. As the mine workings flood, the natural groundwater gradient to the north-northeast will be re-established. Water quality will be monitored in the mine workings through the GEM series of wells on an annual basis. Alluvial water levels, as indicated in wells PAW-5 upstream of the mine and PAW-6 downstream of the mine, continue to show normal variation due to seasonal influences and no impact to alluvial water levels can be identified at this time. Extremely high iron in PAW-6 is noted. This may be a function of well casing composition and oxidation. Alluvial water quality remains slightly more saline than the surface water which recharges the alluvium, but is within an acceptable range for all known and current uses. Quality changes due to mining are not apparent. Spring and Seep Survev The spring and seep survey was conducted August 6 through August 27, 1999 in accordance with the approved plan. Spring #1 in Cherry Canyon was observed as dry. Flows at nearby