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Ground water monitoring well GW -N9 (see Map 2.04.7-1) was installed by Peabody and quarterly <br />analyses were conducted from October 1979 to October 1987. This monitoring well is located <br />within the NHN permit area and is open to both the Overburden and Coal zones. The quality data <br />for this well is reported in the New Horizon 1 Mine Area permit pages 7-4-49 to 7-4-53. The <br />average TDS for the period was 3785 mg/l and the average SO4 concentration was 2423 mg/1. The <br />values of these two parameters are significantly higher than the Coal Zone values at GW -N48 and <br />GW -N51. This indicates that water quality in the Coal Zone (and probably the OB Zone) is also <br />dependent on depth or isolation beneath the weathered zone as well as distance from the recharge <br />area. Therefore, water quality is expected to deteriorate in the down dip direction as well as toward <br />areas with higher overburden thickness. The thickest overburden in the NHN permit area is in the <br />southern one third of the area (see Map 2.04.6-3). <br />Underburden Zone Ground Water Quality The quarterly Underburden Zone ground water <br />sample analyses from wells GW -N47, GW -N50 and GW -N53 are contained in Appendix 2.04.7- <br />1 along with the hydrographs and water level data. These three wells have been monitored and <br />samples collected since October 10, 2008. Review of TDS and SO4 from the three wells show that <br />wells GW -N47 and GW -N50 (see Map 2.04.7-1 for well locations) have poorer water quality than <br />the Coal Zone at the two corresponding sites; whereas, the Underburden Zone water quality at well <br />GW -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 with <br />the underburden samples. Sulfate exceeds the drinking water standards at all three wells while iron <br />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 the <br />old backfill area while the third was a spring issuing from the high -wall of the Nucla Mine after <br />mining ceased in 1983. These three "springs" were monitored from 1983 through 1987. The water <br />quality and flow data for spoil springs SS#1, SS#2 and SS#3 are contained in the Appendix of <br />Section 2.04.7-2. Spoil Spring (SS) #1 is located along a reclaimed drainage at the toe of the <br />backfill of the old Nucla Mine. SS #2 was located about 50 yds up -stream and to the west of SS <br />#1. The high -wall spring issued from the base of the overburden zone at or very near to the contact <br />Section 2.04.7 Page 12 Sept. 2015 (TR -11) <br />