2008-02-29_REPORT - C1982056 - Laserfiche WebLink

Home Browse Search

is available in previous AHRs. The last flows measured for 2000 showed seasonal variations, with an average annual flow of approximately 65 gpm. The EMD was monitored periodically at the lORT well shaft during 2007. Northern Mining District (NN]D): At the time of the 2007 inflow study, the mine operation was nearing the middle of the 21 Rt panel. During 2007, the main sources of water came from the two most recent shafts in the 6MN area, and two fault crossings. Total inflow is estimated to be on the order of 80 gpm. Inflows continued in the Northeast Submains, although there appears to be a continued decrease in ceiling dripping. The highest inflows were about 20 gpm for the new 6MN shaft, and about 15-20 gpm from a floor sump at inflow site 8 (IF8) with a conductivity of 2268 (Trout Creek Water). This may have been impacted by the addition of roof drip collection to the sump system. The next highest inflow was at raise bore area (1F 38 and 1F 37), which was also on the order of 10-15 gpm (down from an estimated 20 gpm in 2005), Field conductivity measurements were about 1500 umhos/cm. This site is a blend of Wadge and Twentymile Sandstone water. Inflow at the remaining sites (primarily roof drippers) were significantly lower, often less than a gallon per minute. 4.0 SUBSIDENCE IMPACTS During the second-half of 2007, mining included the 20RT panel and the start of the 21RT panel. Water quality data was collected from established sites along Fish Creek in areas underlain by gate-roads or longwall panels in previous years. In 2007 there was no active mining beneath Fish Creek, and therefore no additional subsidence beneath Fish Creek. Structures remained essentially unaffected during the period as reflected in the data and on • the associated subsidence map. No adverse impacts, i.e. imminent failure of structure, were evident (For additional detail, review the First Half 2007 Subsidence Survey Report, submitted to DRMS in July 2007). A Second Half 2007 Subsidence Report is anticipated to be submitted to DRMS in February 2008. Fish Creek: Historically, hydrologic monitoring of potential subsidence impacts from the earlier 17 and 18 - Right Panels utilizes four alluvial wells and four nearby surface sites. These sites are shown on the attached First Half 2007 Subsidence Map. These include alluvial well AVF-14 and associated surface site SW-14 (upstream of 17-Right subsidence zone). Also utilized are alluvial we11008-AU3 and associated surface Site 305 (downstream of 17-Right subsidence zone). Note that sites 305 and 008-AU3, were designated under TR03-42 as downstream subsidence monitoring sites. Alluvial well AVF-15 and associated surface site SW-15 are located between the two sets of upstream and downstream sites, presently within a ponded subsidence zone. Localized ponding occurred in this area in September/early-October of 2004. The creek bed flow path has subsequently reestablished itself. A portion of Fish Creek was last subsided in 2006. In that year, a short segment of Fish Creek crossed approximately 160 feet into the zone of anticipated subsidence (based on the subsidence limit line) along the extreme eastern edge of the 19-Right Longwall Panel. Minimal subsidence impacts were noted along roughly 500 linear feet of Fish Creek, in this area. Note that during 2006 and 2007, no significant ponding effects were . observed in this area. Hydrologic monitoring in 2007 did not indicate significant water quality impacts to Fish Creek. Iron concentrations for surface sites SW-14, SW-15, and 305 ranged from 290 ug/1 to 4280 ug/1. Note that seasonal fluctuations in the concentrations of some analytical parameters (e.g. iron, conductivity, TDS, etc.) 14