2012-06-20_PERMIT FILE - C2010089A (10)

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water quality is expected to deteriorate in the down dip direction as well as toward areas with higher overburden thickness. The thickest overburden in the NHN permit area is in the southern one third of the area, (see Map 2.04.6 -3). Underburden Zone Ground Water Quality The quarterly Under - burden Zone ground water sample analyses from holes GW -N47, GW -N50, and GW -N53 are contained in Appendix 2.04.7 -1 along with the hydrographs and water level data. These three holes have been monitored and samples collected since October 10, 2008. Review of TDS and SO from the three holes show that holes GW -N47 and GW -N50 (see Map 2.04.7 -1 for hole locations) have poorer water quality than the Coal Zone at the two corresponding sites; whereas, the Under - burden Zone water quality at hole GW -N53 is better than the coal zone quality for that site. The shallow depth of the coal zone at the two holes, GW -N47 and GW -N50, indicates that weathering has removed (oxidized) at least to some degree the higher sulfur content that is to be expected in the coal zone. The poorest water quality of the three new Underburden Zone holes is at GW -N47 located in the northeast corner of the NHN permit area. This condition differs significantly from the overburden and coal zones where the poorest quality water was at the southwestern site or at holes GW -N54 and GW -N55. This suggests that the area of primary recharge for the under - burden in the northwest corner of the NHN Permit area may be other than the 2 Park Lateral. Table 2.04.7 -3 summarizes the ground water quality from the analyses of the samples from the three underburden monitoring holes. The WQCC ( Regulation 41) water quality standards are also included on this table for comparison with the underburden samples. Sulfate exceeds the drinking water standards at all three holes while iron and manganese exceed drinking water standards at holes GW -N47 and GW -N50. Springs and Seeps Three springs were defined in and in close proximity to the southern part of the NHN permit area by Peabody at the old Nucla Mine, (see Map 2.04.7 -1). Two of these springs were at the toe of the old backfill area (spoils) while the third was a spring issuing from the high -wall of the Nucla Mine after mining ceased in 1983. These three "springs" were monitored from 1983 through 1987. The water quality and flow data for spoil springs SS #1,SS #2 and SS #3 are contained in the Appendix of Section 2.04.7 -2. Spoil Spring (SS) #1 is located along a reclaimed drainage at the toe of the backfill of the old Nucla Mine. SS #2 was located about 50 yds up- stream and to the west of SS #1. The high -wall spring issued from the base of the overburden zone at or very near to the contact with the coal zone. The flow of all three of these springs appeared to vary with the seasonal irrigation, (see New Horizon 1 Mine Area permit). Flow rate varied from a 16.6 gpm to about 47 gpm during the irrigation season at SS #1 to a rate of 16.6 gpm to 32 gpm during non - irrigation periods. SS #3 had a much lower flow rate estimated at about 0.3 gpm during the fall of 1986. The only quantifiable flow rates from the high -wall (SS #3) were during the irrigation season and were measured at about 4.5 gpm. Spoil Spring #3 (SS #3) in the highwall was covered with backfill material when the old Peabody highwall was reclaimed in 1992. During 2001, SS #1 was again monitored (part of close out monitoring for old Peabody permit area) and the data from this monitoring is included in the Appendix2.04.7 -2 to this section. While water quality was similar at SS #1 from 1987 to 2001, the flow rate appears to have increased 3 to 4 fold. The only explanation for this is that the surface owner has been irrigating (running water over the old highwall reclaimed and backfilled slope) since 1992 to enhance grazing opportunities. Section 2.04.7 Page 10 November 2011