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FIRST HALF 2007 SUBSIDENCE REPORT Hydrologic monitoring of potential subsidence impacts from the 17-, 18-, and 19-Right Panels utilizes three alluvia] wells and three neazby 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 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 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. Fish Creek has subsequently re-established its flow path in this azea. A small section of Fish Creek crosses approximately 160 feet into the angle of draw zone along the extreme eastern edge of the 19RT panel system. Minimal subsidence impacts were anticipated along roughly 500 lineaz fee[ of Fish Creek, and following mining of the 19RT panel in this area, no significant ponding effects were observed. Hydrologic monitoring in 2007 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 pazameters (e.g. iron, conductivity, TDS, etc.) do occur at the surface sites. Increases in iron concentration aze often related to accumulation and leaching of iron-bearing strata/sediments during spring runoff erosion. 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. • 2007_1stI-IalfSubReport.doc Page 2 of 2 6/18/2007