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• northwest along the eastern flank of the Fish Creek anticline up to .762 ft/ft further <br />east of the anticline where the flow direction is predominately to the north. Pest of [he <br />Fish Creek anticline, the direction of ground water flow in the overburden is generally <br />towards the northwest. Gradients are lower west of the anticline, ranging from .070 ft/ft <br />near gage Creek to .742 ft/ft (YOV29 to the permit boundary) near the axis of the <br />anticline. <br />Exhibit 7-3 presents the po [entiomet ric surface of the VadBe coal seem. The Yadge coal <br />potentiometric surface was constructed using the arithmetic mean of the values for the <br />period of record that are believed valid (Table 7-3). Pater levels used to construct the <br />Yadge coal potentiometric surfaces are contained in Appendix 7-2. Ground water in the <br />Yadge Coal seam otturs under confined conditions at relatively short distances <br />downgradient of the trop. <br />East of the Fish Creek anticline, ground water in the Yadge coal seem flows to the north <br />and northwest. Flow gradients range from .135 ft/ft to .253 f[/ft nearer to the axis of <br />the anticline. west of the anticline, flow directions ere generally to the northwest, <br />• although locally trend to the north near the anticline and to the west downgradient of <br />Well YW18. The Wadge coal downgradient (west) of YY18 exhibits the steepest gradient <br />within the Yoast area, .185 ft/ft. Further west, ground water gradients in the Yadge coal <br />lessen in the vicinity of the western permit boundary near Sage Creek (.087 ft/f t). <br />Exhibit 7-4 presents the potentiometric surface of the Wedge underburden geologic unit. <br />The potentiometric surface for the Yadge underburden was constructed using the arithmetic <br />mean of valid water levels collected during the baseline monitoring period (see Table <br />7-3). Appendix 7-2 contains the water level data used to construct the Yadge underburden <br />potentiometric surface. In the northern portion of the Yoast area, only two wells (TYU28 <br />and YYU29) monitor the Yadge underburden downgradient of the Wedge coal. Based on water <br />levels collected at these two wells, the potentiometric surface of this lower unit has <br />been estimated and is plotted as single contours on Exhibit 7-4. Pater level monitoring <br />at both wells indicate the Wadge underburden is completely saturated et these locations. <br />in the southwestern portion of the Yoast permit area, ground water flows to the northwest, <br />exhibiting gradients ranging from .129 ft/ft up to .197 ft/ft towards the south. <br />. Rechara e. The principal sources of recharge to the bedrock units (overburden, Yadge coal, <br />end underburden) ere infiltration of rai of ell and snowmeli at outcrop areas which parallel <br />[he axis of the Fish Creek anticline. Vertical flow movement within the Yadge overburden <br />23 <br />