REP36243 - Laserfiche WebLink

Home Browse Search

FIRST-HALF 2006 SUBSIDENCE REPORT V. Hvdrologic Monitorine: During the first-half of 2006, water quality data was collected from established sites along Fish Creek, in azeas underlain by gate-roads or longwall panels, as well as from representative downstream sites located away from the subsidence azea. Hydrologic monitoring of potential subsidence impacts from the 17- and 18-Right Panels utilizes three alluvial wells and three neazby surface sites. These sites aze shown on the attached First-Half 2006 Subsidence Map. These include alluvial Well AVF-14 and associated surface Site SW-14 (upstream of 17-Right subsidence zone). Also utilized are alluvial Well 008-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 subsidence monitoring sites. Alluvial Weli 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 azea in September through early-October of 2004, and has persisted through the first half of 2006. A short segment of Fish Creek crosses 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 anticipated along roughly 500 lineaz feet of Fish Creek, in this azea. Note that during 2006, no significant ponding effects were observed in this azea. Hydrologic monitoring in 2006 did not indicate significant water quality impacts to Fish Creek. Summary tables of monitoring data for the subject surface sites and alluvial wells are attached. Note that seasonal fluctuations in the concentrations of some analytical parameters (e.g. iron, conductivity, TDS, etc.) do occur at the surface sites. Increases in iron concentration are often related to accumulation and leaching of iron-bearing strata sediments during spring runoff. Some elevated iron concentrations may also be related to ponding effects (e.g. increased solids in ponded samples). V. Conclusions: Structures remained essentially unaffected during the period, with the exception of the predicted impacts to the powerlines pazallel to the 19-Right Panel. No adverse impacts, i.e. imminent failure of structures, were evident with regazd to these structures. Subsidence surveys disclosed no unusual developments during the reporting period. Subsidence magnitudes and projected draw angles were within the anticipated ranges previously documented for the area. Hydrologic monitoring did not indicate significant water quality impacts to Fish Creek. 2006_IstHa115ubReport Rl.doc Page 2 of 2 12/IS/2006