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SITE SPECIFIC GROUNDWATER INFORMATION AND BASELINE DATA <br />Regional and site specific geology and physiography pertinent to the description of groundwater <br />resources in the NHN permit area are discussed in Section 2.04.5 and 2.04.6. Maps 2.04.5-1 <br />(General Geology and Hydrology Map), 2.04.6-4 and 2.04.6-5 (Geologic Cross Sections A —A' <br />and B -B') graphically illustrate the site specific geology at the NHN permit area. The permit area <br />is drained to the west and north by tributaries of Coal Canyon and to the south by tributaries of <br />Tuttle Draw. The surface water divide between Tuttle Draw and Coal Canyon is located in the <br />southernmost part of the mining area. Relatively deep incision of the strata to be mined by Coal <br />Canyon, Tuttle Draw and their tributaries results in a somewhat small and isolated hydrologic <br />system. This system is completely isolated from the New Horizon Mine effects on both surface <br />and groundwater because of the stream incision of Tuttle Draw. The projected outcrop of the <br />LDx Seam is shown on Map 2.04.6-1. The relative shallow strata of the affected groundwater <br />system and the relatively small area of the surface drainage system are totally dominated by the <br />effects of seasonal irrigation. Irrigation was brought to Nucla in 1904. Map 2.04.7-1 shows the <br />locations of the "2nd Park Lateral" the primary artery of the irrigation system in the permit area. <br />Disturbance within the permit will primarily affect the topography, the overburden unit and the <br />coal unit. The underburden will be day -lighted by the pit floor but otherwise left in place. The 2nd <br />Park irrigation water has been diverted through a HDPE pipeline during and after mining. <br />Irrigation within the permit boundary will not occur during mining, but will be reinstated to <br />support post -mine reclamation areas that require irrigation. Percolation of water from the 2nd <br />Park Lateral and the flood irrigation during mining into the underlying strata will be eliminated. <br />The effects of reducing the recharge into both the groundwater and surface water systems are <br />discussed in the following sections. <br />Baseline Groundwater Levels New Horizon and Peabody maintained and operated a <br />groundwater monitoring network in the NHN permit area consisting of 15 monitor wells (see <br />Map 2.04.7-1). Each monitor well was measured for static water level on a monthly basis. While <br />monitoring of some of these wells has been suspended and others have been plugged and <br />abandoned, the data from these wells provide historical reference and this information is <br />contained in Elk Ridge Mining and Reclamation's New Horizon 1 and New Horizon 2 permit <br />documents. None of these older wells are currently being monitored. Monitoring wells GW -N47 <br />through GW -N55 were added in the NHN permit area in October 2008 (see Map 2.04.7-1). <br />Typical completion diagrams one each for the overburden, coal zone and underburden well <br />completion monitoring zones are provided in Figure 1 of Appendix 2.04.7-1. Water level and <br />water quality monitoring began immediately upon completion of these wells. Water levels of <br />these wells are measured on a monthly basis and water quality samples are measured quarterly. <br />The tabulated water level data and resulting hydrographs are contained in Appendix 2.04.7-1. <br />Review of the hydrographs indicates that there is separation of the three zones (underburden, <br />coal, and overburden). Further, most of the monitoring wells show a gradual decline in water <br />Section 2.04.7 Page 2 March 2018 (TR -16) <br />