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• During the fast and second halves of 2001, subsidence survey data was collected periodically from established <br />monuments on the Union Pacific Railroad, Routt County Road No. 33 and Foidel Creek in areas underlain by <br />gate roads or panel centers relating to the recent completion of mining and subsequern sealing of 12-Rt. This data <br />was presented to DMG in detail in two semiannual subsidence reports for 2001 (First Half, and Second Halj <br />2001 Subsidence Survey Report). The results of these reports are summarized here. Subsidence monument <br />surveys disclosed no unusual developments during the reporting period. Subsidence magnitudes and projected <br />draw angles were within the anticipated ranges previously documented for the azea. <br />Stmctures remained essentially unaffected during the period with the exception of the predicted impacts to the <br />Union Pacific Railroad and Routt County Road No. 33. No adverse impacts, i.e. imminent failure of structure, <br />were evident with regard to these structures. Potential ponding along Foidel Creek, relating to subsidence effects <br />of 12 Rt mining, may not start to become evident until the spring runoff for 2002, Areas overlying 12 Rt will be <br />surveyed and reported as appropriate in 2002. <br />Middle Creeks As shown on Figure 136, Middle Creek Profile Over Panels 2 Rt through 6 Rt, no significank <br />changes to the creek channel were noted. Current survey data shows that no ponds were formed over the mined <br />out panels. <br />The flow data presented on Table 75 indicates there is no lost of water from the system from the upstream to the <br />• downstream site. This pattern is consistent throughout the yeaz. The water quality data indicates that both EC <br />and sulfate concentrations typically increase from the upstream to the downstream sites. This could be a <br />reflection of the irrigation return flows having increased salt concentrations. However, the water quality is not <br />exceedingly de~aded by this increase during the irrigation season It is noted that iron concentrations are higher <br />than on Foidel Creek. The iron concentrations in Middle Creek fluctuate, with the upstream site being typically = <br />lower than the downstream site during April and May and the downstream site typically lower than the upstream <br />site during August and September. These variations do not appear to be associated with the mining operation. It <br />does not appeaz that undermining the creek resulted in adverse impacts. <br />The fatal subsidence profile for Middle Creek over 2 Rt was surveyed in July 2001 and was submitted to DMG in <br />drawing form as part of the fast half 2001 Subsidence Report. <br />5.0 S~TMMARY AND CONCLUSIONS <br />No significantlunexpected hydrology impacts, attributable to the activities or developments at the Foidel Creek <br />Mine, were noted during 2001, with the exception of elevated conductivity and iron measurements during mine <br />dewatering at site 115. The previously noted declining water level trend in Wadge Overburden well 91M006 <br />(Figure 9) appears to have continued during 2001. This trend may be related to localized dewatering of the <br />formation as a result of mining activities in the vicinity. The marked decline in water level noted in 1999, in <br />wells 93M001 (Figure 13) and 93M003 before it was abandoned (Figure 15), appears to wrresp®nd to longwall <br />mining in the EMD. No significant water quality degradation is noted for the Wadge Overbuuden formation as a <br />result of evaluating data collected during 2001. <br />15 <br />