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State Reg. • ~ the Lennox coal seam and overburden, causes the ground water to be- come confined. The level to which water will rise in o well completed in a confined aquifer is termed The potentiometric surface. Flowing wells may occur in areas where the potentiometric surface is above the land surface. Observation wells GW-SI I and GW-519 are examples of this effect. ii. Potentiometric Surface 2.04.7(IXa) Exhibit 7-2 is a potentiometric surface map which illustrates the flow (i) directions of shallow ground water within the permit area. Contours are drawn in one hundred foot intervals for the Wadge seam, Wolf Creek seam, overburden, and alluvium. Water levels range from approximately 6900 feet (msl) to 7750 feet (msl) for the Wadge seam, and approximately 7435 feet (msl) To 7990 feet (msl) for Wolf Creek strata. This gives an overall potentiometric surface relief of greater than 850 feet for the • Wolf Creek and of 555 feet for the Wadge. Examination of the potentiometric map shows that the potentiometric gradients conform with structural gradients mentioned earlier. Ground water will flow perpendicular to potentiometric gradients as shown in Exhibit 7-2. The axis of the Tow Creek Anticline acts as a ground water divide, thus ground water on the east flank of an anticline will flow eastward into the Twentymile Park syncline. Ground water flow on the west side of the axis will move into the Hayden syncline. The relation- ship of geologic structure to regional ground water flow in the Seneca I! Mine permit area was previously discussed in the section on regional ground water occurrence (see Exhibit 6-12). As shown in Exhibit 7-2, reclaimed spoil areas are for the most part unsaturated. Only the lower portion of the reclaimed area contains water which discharges into the Wadge Impoundment and then flows into Grassy Creek. • Recharge occurs along outcrops along the crest of the Tow Creek Anti- cline. Discharge for the confined aquifers occur along structure and from springs. The location of these springs are given in Exhibit 7-2. i 7-45 Revised 5/27/81