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New Horizon Adjacent North Ground Water Monitoring Holes <br />Four holes are planned to be drilled at each of three sites. One of these holes at each of <br />the sites will be drilled as a pilot hole and will be logged with geophysical tools. The <br />other three holes will be constructed as groundwater monitoring holes. After reviewing <br />the logs from the pilot holes, the depths for the monitoring holes will be determined. At <br />each site, one monitoring hole will be constructed in the overburden above the coal zone, <br />another within the coal zone, and the third below the coal zone. <br />All holes will be drilled using a truck-mounted rotary drill rig. The pilot holes will be <br />drilled to a diameter of 5-1/8" or 5-5/8" and will be drilled through the Nucla Seam, a <br />thin coaly shale seam usually found between 15 and 30 feet below the Upper and Lower <br />Dakota seams which are the seams targeted for mining. Each of the three pilot holes is to <br />be logged immediately after the hole is drilled. Upon review of these logs, the depths and <br />specific construction details for each of the monitoring holes will be decided. <br />The construction of the monitoring holes is subject to the findings of the geophysical logs <br />from the pilot holes but will follow the following general guidelines (See Figure 1). Each <br />hole will be drilled to a diameter of approximately 6-1/2". Once drilled, the hole will be <br />cased with 4" schedule 40 PVC casing. In the case of the hole that will monitor water <br />above the coal zone, the total depth of the hole will be several feet above the Upper <br />Dakota (UDI) seam. The lower ten feet of casing will be mill-slotted PVC. Above the <br />slotted casing, a soft-formation packer will be placed on the casing and 3/8" bentonite <br />pellets will be poured down the annulus on top of the packer to an elevation of ten feet <br />above the packer. Drill cuttings will then be placed on top of the bentonite pellets to a <br />depth of five feet from the surface. Concrete will be used to grout from the surface to the <br />top of the drill cuttings. <br />The holes monitoring groundwater within the coal zone will be drilled to the bottom of <br />the Lower Dakota (LDx) seam. Slotted casing will be used from the total depth to the top <br />of the UD1 seam. A soft-formation packer will be installed above the slotted casing and <br />10 feet of bentonite chips will fill the annulus above the packer. Drill cuttings will be <br />placed in the hole to a depth of five feet from the surface. The final five feet will be <br />grouted with concrete. <br />The holes completed below the coal zone will be drilled to a depth of approximately <br />fifteen to 30 feet below the LDx seam. Slotted casing will be used from the total depth to <br />just below the bottom of the coal seam. A soft-formation packer will be placed just <br />below the bottom of the lower seam and 3/8" bentonite pellets will be poured in to a <br />depth of several feet above the UDl seam. Drill cuttings will be placed in the hole to a <br />depth of five feet from the surface. The final five feet will be grouted with concrete.