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3.0 Hydrologic Consequences <br />There is potential for dewatering of groundwater aquifers located within and above the Maxwell coal seam <br />member of the Raton Formation. Previous studies included in the mine permit document project inflow of as <br />much as 180 gpm and indicate an azea of influence on groundwater up to 2,1 miles from the perimeter of the <br />mine workings. The average dischazge when discharge occurred from the mine at Pond 002 was 76 gpm. The <br />maximum discharge from Pond 002 was 148 gpm. The workings aze now flooding, which is resulting in <br />changes in the potentiometric surface around the mine back to premining conditions. <br />Localized dewatering was evident from the flow of groundwater (seeps, etc.) into the underground mine <br />workings, and the pumping and dischazge of these mine waters into surface flows. However, no loss of springs <br />or impacts to existing adjudicated wells have been noticed to date. Relatively constant flows suggest a general <br />low quantity of water within the formations, and retention of member integrity with retention of low vertical <br />transmissivity of free water. <br />There has been no noticeable impact on groundwater hydrology from the gradual flooding of the Golden Eagle <br />Mine. The apparent low vertical transmissivity and integrity of the surrounding rocks might inhibit any effect <br />of free water on the recharge of the overburden. Monitoring of the underground workings began in 1997 at <br />GEM-1, GEM-2, and GEM-3. Rate of filling of the workings has been monitored through time and no effects <br />have been identified. Table 3.1-1 presents the average water level data for the three wells. All data is <br />presented in Appendix A. GEM-1 showed a rise in water level of ] 0 feet in 2005. GEM-2 had water for the <br />first time in the fourth quarter of 2000 and the level was stable during 2005. GEM-3 and the associated shaft <br />were reclaimed in July 2005. GEM-1 is the highest elevation of the mine floor of the three GEM wells. Water <br />measured at this site probably spilled to the north into the extensive area of longwall mining north of Highway <br />12. As measured, the current potentiometric surface of water in GEM-1, GEM-2 and GEMS is approximately <br />6814. All areas ofthe mine appear to be filled and the rise in the wafer level at GEM-1 is a result hydrostatic <br />pressure. <br />3.2 WATER QUALITY <br />' PAW-6 documents an additional loading of dissolved solids greater than that observed at PAW-5, in that it <br />detects mine water discharges. Solids levels in the PAW-6 samples show decreases from previous years which <br />' indicates that effects ofmine water discharge are diminishing. Recent TDS levels from PAW-6 are similar to <br />those ofPAW-5. Figure 3.2-1 shows water quality at the two PAW stations. However, the historic records <br />of PRS-3 indicates little effect on stream quality from the local sources of alluvial groundwater. Well CLAW-1 <br />is located down gradient of the development waste storage area and shows elevated levels of dissolved solids <br />' (Figure 3.2-1). However the sample collected in 2006 shows a significant decrease in TDS from historic <br />samples. <br />' Basin monitored the overburden and the coal seams adjacent to the mine. The five overburden wells were <br />completed in zones of elevated flow during drilling, and consequently reflect different strata. Two overburden <br />wells located north of the workings, NM-20 and NM-22 exhibited very alkaline conditions (pH ranging from <br />' 9.9-I 1.85) and were sodium carbonate waters. They have moderate salinity with conductivities ranging from <br />400 - 504 mg/1. There aze four coal wells associated with the monitoring progam. Site NM-23, north of the <br />Golden Eagle workings is a slightly acidic (pH 5.74 - 6.2), very saline (TDS of 2400 mg/1) sodium/iron <br />' chloride water. Previously this was an excessively alkaline (pH 9.4 - 11.46) sodium bicarbonate water. Again, <br />there is some thought that the pump extraction process modified the chemistry of the water. This site has <br />elevated iron concentrations, and levels ofmanganese and chloride which exceed ground water standards. No <br />water quality samples were collected from deep wells during 2005 as a result of the new monitoring program. <br />Water quality of the mine workings have been monitored as the mine is allowed to fill. Water samples have <br />been collected at GEM-1 since 1999 and GEM-2 since 2002. The water is a sodium bicarbonate type with <br />29234 Golden Eagle Mine Rpt (S.I0.06).doc 3-3 <br />