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. mg/l), however these values are within historic ranges. Figure 12 illustrates the variable nature of total <br />recoverable iron concentrations in the No. 1 Strip Pit discharge. Since 2003 there has been a gentle upward <br />trend in iron concentrations, however these levels are still within historic ranges seen for this site. <br />3.2.3 Ponds <br />With the exception of Outfall 003 (discussed under section 3.1.2), there was no discharge from the other <br />sediment ponds in 2005. <br />4.0 SUMMARY AND CONCLUSIONS <br />No significant, unpredicted, or adverse environmental impacts were noted during hydrologic monitoring for <br />2005. All monitoring requirements were met. <br />Under the temporary cessation monitoring plan, there are seven events that might trigger reversion to the <br />active mining plan occurred (see TROI-32, Appendix D, June 21, 2001). These events are discussed below. <br />1. The water level in the No. S Mine workings.(F seam) at the 7 North Angle (7NA) well location <br />exceeds elevation 6,000 feet (i.e. approximately < 400 feet from surface). This was not exceeded <br />(See Table 9 A). <br />2. Combined pumping from the No. S Mine well and the 7 North Angle well exceeds an average of <br />2000 gpm during any period of four consecutive weeks. The No. S Mine well pump has a maximum <br />capacity of 600 gpm. The 7NA pump has a maximum capacity of 500 gpm, therefore, the 2000 gpm <br />limit cannot be exceeded. Also note that the 7NA pump was not operated in 2005. Specifications <br />for these pumps was provided as an addendum to the 2004 AHR (BTU Empire letter dated 6/1/05). <br />3. Field or lab conductivity of a sample (adjuster! to 25 degrees Celsius) from NPDES outfai1024 (site <br />9P3) exceeds 2,000 micromhos/cm. Site 9P3 did not flow in 2005. <br />4. Yampa River flow measured near Maybell (USGS site 09251000) drops below 100 cfs on August 1 <br />in three consecutive years. Flow for USGS site 09251000 was measured at 215 cfs on August 1, <br />2003, at 165 cfs on August 1, 2004, and 436 cfs on August 1, 2005. (See attached USGS data <br />sheets). Therefore the minimum limit of 100 cfs was met during three consecutive years. <br />5. New roof fall of more than 500 square feet is suspected in the No. S or 6 Mine. MSHA inspected the <br />mine quarterly from the time the mine closed in 1495 until the Portals were sealed in 2002. The last <br />M5HA documented roof fall (216 sq feet) was in 1997. MSHA reports dating from 1983 to 1997 <br />were provided as an addendum to the 2004 AHR (BTU Empire letter dated June 1, 2005). <br />. Historically, roof conditions were excellent to the point where roof bolting was no[ deemed <br />6 <br />I:\Env\Empire W H R\2005\Text\Empire2005AH R.doc <br />