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2.7.5.1b Aquifer Characteristics, Eastern Expansion Area <br />Trapper submitted PR -07 in May of 2013 with the intent to extend the perimeter boundary of the mine <br />to the Knez Divide road, otherwise known as Moffat County Road 33. This small permit extension <br />adjoins the active mine area and permit boundary as of 2013. The relevant geologic units in this <br />expansion are present minewide. Sections 2.7.5.1 and 2.7.5.1a both contain relevant information to the <br />area, particularly section 2.7.5.1x. <br />Known geologic units within the eastern portion of the mine appear to continue to extend easterly in <br />the Upper Unit of the Williams Fork Formation. Trapper has conducted extensive core drilling in the <br />expansion area. The geologic setting is the same for the permit extension area as that presented in the <br />Trapper Permit. Figure 2.7 -4 in the Trapper Permit presents the structure of the basin in the area of the <br />mine. Structure of the coal seams has been extended to cover the permit extension area. These <br />structure maps show that the typical dip to the north in the northeastern portion of the Trapper permit <br />area is changing to the northwest in Section 28 TGN R90W. This change fits the regional structure <br />change that is shown in Figure 2.7 -4. <br />Using the projected structure maps of coal seam thicknesses, roof and floor locations the potentiometric <br />water levels were extended to the east of the active mine area. Current levels are shown on Map M54 <br />and the 2013 Annual Hydrology Report, (TR -113.) The structure maps for I and R coal seams were used <br />to aid in the extrapolation of the water -level elevations for the HI and QR aquifers in the permit <br />extension area. The structure map for the H seam was used in the extension of the water -level <br />elevations for the Third White Sandstone because the base of this sandstone is near the top of the H <br />coal_ <br />The water -level elevations in the QR aquifer were extended in the permit extension area accounting for <br />the change in the dip of these beds from the north to the northwest. This structure change causes the <br />water- level contours to curve to the northeast in the permit extension area resulting in ground -water <br />flow to the northwest Instead of the northerly flow that occurs to the west of this area. Similar changes <br />in the flow directions in both the HI and Third White Sandstone aquifers also occur in the permit <br />extension area and to the north of the extension area. <br />The anticipated water yield of the aquifers in the extension area should correspond with the <br />determinations made in section 2.7.5.1a, Table 2.7 -21b. Current monitoring wells completion <br />information is contained in Table 2.7 -20. The wells utilized in section 2.7.5.1a to determine aquifer <br />characteristics are applicable to this area. A new series of monitoring wells will be completed in the <br />expansion area to obtain better water level elevations and water quality data on the eastern edge of the <br />mining area. However, present data suggest the water quantity will not be vastly different in the area <br />when compared to data gathered in nearby existing wells. <br />Wells such as GP -7 and GP -8 are located adjacent to the PR -07 expansion area. These two wells are now <br />only beginning to experience impacts from mining to their west in L and K pits. The water quality data <br />from these wells is a good baseline for the eastern edge of the mining area. Water quality in this area <br />has not differed significantly from previous studies of the mining area. <br />Y avision a <br />2 -462m <br />Approved: <br />