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' Water levels in the backfilled pit are measured at Wells BF-1 and BF-2, installed to monitor the recovery of the water table within the backfilled pit. The wells were drilled in mid- ' December of 1997 and have never shown significant fluctuation. The water table appears to have stabilized much sooner than anticipated. Several things may have contributed to this, ' including higher than normal precipitation. Several of the studies proposed later in this document will allow BMRI to gain a better understanding of the hydrologic regime, including the magnitude and direction of groundwater flow through the backfill material. In addition to stabilizing sooner than expected, the groundwater elevations are much higher ' than anticipated. The water levels in BF-1 are approximately 12 feet below the top of the backfill, while the levels in BF-2 are approximately lb feet below the top of the backfill. The water table may fluctuate within a 12-inch zone, but limited data is available and the si[e has been experiencing higher than normal precipitation, so long-term fluctuations may differ. ' These higher than anticipated water elevations have resulted in the potential fpr groundwater from the pit to migrate to the steep banks of the Rito Seco and appear as surface seeps on the ' banks. ' 3.2 GROUND WATER QUALITY TR-15 established several groundwater monitoring wells downgradient of the backfilled West Pit [o monitor groundwater quality. These wells included SF-1, DW-2, and M-11, M-10, 87- 24. Table 1 of Appendix A shows the groundwater monitoring wells and the units of completion. Wells DW-2, M-10, and 87-24 are monitored for informational purposes only. Wells SF-1 and M-11 were established as compliance wells. Baseline data wer¢ evaluated for ' these wells. Any data outliers were eliminated, using the Dixon method, and the compliance limit was set at the drinking water standard or the highest value recorded in the well, ' whichever was higher. Each well has separate compliance limits which can be found in TR- 15. ' In the fall of 1995, iron levels in M-11 began to rise and eventually exceeded the compliance limit. M-11 is a shallow well and it was determined that the iron was being produced by iron ' bacteria. This is a common phenomena in the San Luis valley in shallow wells. BMRI decided to abandon M-11 instead of trying to kill the bacteria. A replacement well, M-11R, ' was drilled in the spring of 1996. This well was subject to at least a year of baseline 12