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• installed in the northeast corner of the permit area. Ground water in the underburden aquifer is <br />uhder artesian conditions. Mean artesian heads in the underburden aquifer range from 9.7 feet <br />at Monitor Well GW-N11 to 86.7 feet at Monitor Well GW-N33. The average artesian head for the <br />underburden aquifer is 40.0 feet. <br />A downward vertical head is generally observed in the underburden but an upward (recharging) <br />vertical head is exhibited at Monitor Well GW-N16. All of the underburden monitor wells at New <br />Horizon 1 & 2 display seasonal variability to some degree. The seasonal water level fluctuations <br />at the New Horizon 1 & 2 mining areas range from only a few tenths of a foot at Monitor Wells GW- <br />N3and GW-N11 to nearly 11.0 feet at monitor well GW-N13. All of the underburden monitor wells <br />exhibit steady-state water levels over time with the exception of Monitor Wells GW-N1, GW-N1 P1 <br />and GW-N6. These wells have displayed a slight shallowing trend with time. There were no <br />distinguishable effects from the mining operation at New Horizon 1 area or recharge from <br />precipitation events on the underburden aquifer system. <br />I Saoil Water Levels. Four monitor wells (GW-N10, GW-N26, GW-N27 and GW-N28) were <br />• installed to monitor water levels in the spoil aquifer at the New Horizon 1 area. Map 2.04.7-1A <br />shows the spoil monitor well locations. Monthly water level data including hydrographs are <br />contained in Attachment 2.04.7-6 (formerly Peabody Appendix 7-1 ). <br />The spoils aquifer is dry or nearly dry except for the area in the vicinity of GW-N27. At this location <br />the spoil aquifer has approximately 6.4 feet of saturation. This well was installed in August of 1987. <br />In general, this well has shown seasonal fluctuation in the water level to correspond with the <br />irrigation ditch flow. <br />Multiale Comaletion Well Water Levels. Five wells with multiple seam completions have been <br />installed at the New Horizon 1 area (Map 2.04.7-1A). Monitor Wells GW-N8 and GW-N9 were <br />installed in the overburden and the Dakota coal aquifers northwest of the New Horizon 1. Monitor <br />Wells GW-N23, GW-N24 and GW-N25 were located in what had been referred to as the scraper <br />area in the southeastern portion of the permit area. Those monitor wells were completed in early <br />June, 1986 in the overburden, Dakota coal and underburden aquifers. Water level information <br />indicates that the scraper area monitor wells are dry. Water level information has been gathered <br />f, J <br />REVISED JULY 2006 2.04.7-10 <br />