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_ low permeability, limited continuity, low yield and relatively poor water quality. These factors preclude utilvation of • the ground water contained in this sequence for all practical purposes, except small stock watering installations. The Wadge Overburden is directly affected by the mining operation. Field data from ground water monitoring wells shown on the Twentymile Park Hydrology Map (Map ]3) were used to construct a potentiometric contour map for the Wadge Overburden sequence in this area for August-September 1983 prior to the start of underground mining. The potentiometric map for the Wadge Overburden was constructed using only water level date which were deemed to be reliable. Previous potentiometric maps had used water level data from wells that were not fully completed in the Wadge Overburden sequence. The following criteria were used to select data for construction of the map. 1. Water level data must be from wells that have reliable completion information to confirm that the well is completed th the Wadge Overburden. 2. Overburden wells in the center of the Twentymile Park Basin, where flowing artesian head conditions exist, must be adequately "shut-in" to obtain a reliable pressure reading. 3. Water level data must be taken with the period of August to September, 1982. Water level elevation data from Wadge Overburden wells which met all the above criteria area shown in parentheses below the well on Map 13, Twentymile Park Hydrology. The Wadge Overburden wells that could not be used for construction of the potentiometric map are listed with the criteria that were not met: Well Criteria Not Meet Comments 001-S W-7 3 001-L-1 3 001-D-5 3 006-W-16 1 No completion data • 006-W-] 7 1 No completion data 006-W-18 1,2 No completion data 006-80-2 1,3 No completion data 006-82-38 1 Suspect completion data 06-81-31 2 06-82-62 3 21-81-16 2 All other wells listed on Table 7, Ground Water Monitoring Well Inventory or located on Map 13, Twentymile park Hydrology, are completed in units other than the Wadge Overburden. Seasonal water level variations in ground water monitoring wells area graphically depicted in Figure 3, Well Hydrographs, and data are listed in Table 8, Ground Water Data. The hydrograph for well 82-48 (Figure 3-b), completed in the Wadge Overburden shows some seasonal variation in the order of 10 to I S feet, but does not show any trend of drawdown that might indicate effects from underground mining. This is the closest Wadge Overburden monitoring well down gradient of the 1983 mine plan area. The fact that the well did not show effects from mining indicate that drawdown from the mine is limited in areal extent. A potentiometric map for 1985 would not show any differences from the 1983 map and therefore was not constructed. The direction of ground water movement in the Wadge Overburden is generally towards the center of the Twentymile Park Basin, as shown by the configuration of the potentiometric surface for this unit (Map 13, Twentymile Park Hydrology). Recharge occurs along the outcrop of the sequence where unconfined ground water conditions exist locally. • The water quality data from Wadge Overburden wells prior to 1979, or from wells which are not directly down gradient from mining activities, indicates that ground water in this aquifer is characteristically asodium bicarbonate type with relatively low concentrations of calcium magnesium and sulfate ions, as depicted graphically in Figure 4- Permit Renewal No. 3 2.04-21 12/10/98