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few other springs and local permanent "damp spots" in the area; however, their combined flow is normally <br />less than 10 gpm and is therefore not significant. 1SP Discharge is a CDPS monitoring point (Outfall 022). <br />There is no sediment pond associated with this spring. Spring water runs down a narrow path through a <br />vegetative filter and discharges directly to the Williams Fork River. The POR discharges for the 1SP are <br />presented in Figure 23 and the 2009 discharge measurements are presented on Figure 24, respectively. The <br />discharge from 1SP increased significantly back in 1989. This may have been due to seepage from the ditch <br />that conveys the 7 North Angle discharge (measured at site 9P3, a.k.a. CDPS Outfall 024)). Site 9P3 <br />discharge began in January of 1989, and has been sporadic. Site 9P3 Discharge rates from 1990 through <br />2003 are significantly lower. 9P3 has not discharged since 2003. Nevertheless, snowmelt and ditch seepage <br />both appear to have some influence on 1SP discharge, as the discharge typically drops to just a few gpm from <br />January through May with a small peak typically in March coinciding with spring runoff. 1SP may be dry <br />from July through November, and in January and February due to freezing. <br />Summaries of the water quality data for this spring are presented in Tables 31 and 32. A plot of POR total <br />dissolved solids for 1SP is presented in Figure 25 and POR iron concentrations are presented on Figure 26. <br />Figure 25 indicates TDS concentrations that are consistent with historic concentrations. Figure 26 illustrates <br />the variable nature of total recoverable iron concentrations in 1SP discharge. Since 2002, there has been a <br />gentle upward trend in iron concentrations, however these levels are still within historic ranges seen for this <br />site. Note that this site did experience a few iron NPDES exceedances in 2009. This appears to have <br />occurred during very low flow periods shortly before the spring stopped flowing altogether. BTU EC will <br />continue to monitor this trend. <br />3.2.3 Ponds <br />With the exception of Outfall 003 (discussed under section 3.1.2), there was no recorded discharge from the <br />other on-site sediment ponds in 2009. <br />4.0 SUMMARY AND CONCLUSIONS <br />DRMS monitoring requirements for the BTU Empire site were met in 2009. The subject mine site ceased <br />active mining operations in 1995, and has been inactive to date, thus, total mined acreage did not change in <br />2009. The mine was subsequently placed in Temporary Cessation under TR01-32. Temporary Cessation <br />status ended in the second quarter of 2006, when BTU EC re-activated full water monitoring activities in <br />anticipation of future re-activation of the mine site, and because a bond release application was also being <br />contemplated for the Utah Tract and Williams Fork Strip Pit portions of the mine property. With the <br />exception of anomalous elevated conductivity values detected in wells TR-4 and 81-01, no significant, <br />unpredicted, or adverse environmental impacts were noted during hydrologic monitoring for 2009. BTU EC <br />• Page 7 <br />G:\Environmental\EMPIRE\AHR\2009\Empire2008AHR.doc