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Ground water monitoring well GW -N9 (see Map 2.04.7-1) was installed by Peabody and <br />quarterly analyses were conducted from October 1979 to October 1987. This monitoring well is <br />located within the NHN permit area and is open to both the Overburden and Coal zones. The <br />quality data for this well is reported in the New Horizon 1 Mine Area permit pages 7-4-49 to 7-4- <br />53. The average TDS for the period was 3785 mg/1 and the average SO4 concentration was 2423 <br />mg/l. The values of these two parameters are significantly higher than the Coal Zone values at <br />GW -N48 and GW -N51. This indicates that water quality in the Coal Zone (and probably the OB <br />Zone) is also dependent on depth or isolation beneath the weathered zone as well as distance <br />from the recharge area. Therefore, water quality is expected to deteriorate in the down dip <br />direction as well as toward areas with higher overburden thickness. The thickest overburden in <br />the NHN permit area is in the southern one third of the area (see Map 2.04.6-3) <br />Underburden Zone Ground Water Ouality The quarterly underburden ground water sample <br />analyses from wells GW -N47, GW -N50 and GW -N53 are contained in Appendix 2.04.7-1 along <br />with the hydrographs and water level data. These three wells have been monitored and samples <br />collected since October 2008. Review of TDS and SO4 from the three wells show that wells GW - <br />N47 and GW -N50 (see Map 2.04.7-1 for well locations) have poorer water quality than the Coal <br />Zone at the two corresponding sites; whereas, the underburden zone water quality at well GW - <br />N53 is better than the coal zone quality for that site. The shallow depth of the coal zone at the <br />two wells (GW -N47 and GW -N50) indicates that weathering has removed (oxidized) at least to <br />some degree the higher sulfur content that is to be expected in the coal zone. The poorest water <br />quality of the three new underburden zone wells is at GW -N47 located in the northeast corner of <br />the NHN permit area. This condition differs significantly from the overburden and coal zones <br />where the poorest quality water was at the southwestern site or at wells GW -N54 and GW -N55. <br />This suggests that the area of primary recharge for the underburden in the northwest corner of the <br />NHN permit area may be other than the 2nd Park Lateral. Table 2.04.7-3 summarizes the ground <br />water quality from the analyses of the samples from the three underburden monitoring wells. The <br />WQCC (Regulation 41) water quality standards are also included on this table for comparison <br />with the underburden samples. Sulfate exceeds the drinking water standards at all three wells <br />while iron and manganese exceed drinking water standards at wells GW -N47 and GW -N50. <br />Springs and Seeps <br />Three springs were defined in and in close proximity to the southern part of the NHN permit area <br />by Peabody at the old Nucla Mine (see Map 2.04.7-1). Two of these springs were at the toe of <br />the old backfill area while the third was a spring issuing from the high -wall of the Nucla Mine <br />after mining ceased in 1983. These three "springs" were monitored from 1983 through 1987. The <br />water quality and flow data for spoil springs SS #1, SS #2 and SS #3 are contained in the <br />Appendix of Section 2.04.7-2. Spoil Spring SS #1 is located along a reclaimed drainage at the <br />toe of the backfill of the old Nucla Mine. SS #2 was located about 50 yds up -stream and to the <br />west of SS #1. The high -wall spring issued from the base of the overburden zone at or very near <br />Section 2.04.7 Page 11 April 2016 (PR -01) <br />