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;~ <br /> <br /> <br />measured with an electric well tape from the top of the casing. Water <br />level monitoring results appear in Table 7. Utilizing the water level <br />data collected hydrographs were plotted for each well to illustrate <br />seasonal variation (see Exhibits 34 through 40). Upon inspection of <br />these plots, it can be seen that during the monitoring period variation <br />of water levels are neglegible. The water level data has also been <br />presented in the form of two potentiometric surface maps (one represent- <br />ing the upper coal aquifer and one representing the lower coal aquifer). <br />The potentiometric surface maps for the upper coal aquifer and the <br />lower coal aquifer are illustrated on Exhibits 43 and 42 respectfully. <br />The shaded area between the water level contours illustrates the seasonal <br />variability from an aerial vantage point (plain view). Both maps show <br />a north-north-east trending hydraulic gradient of about 4-8° correspond- <br />ind to the dip of the coals. Near the outcrop to the south the ground- <br />water conditions suggest water table conditions (storage coefficient <br />of .O1). As the subsurface water migrates north (down-dip) artesian <br />or confined conditions develop (the potentiometric water level rises <br />above the top of the aquifer --storage coefficient of .001). The <br />groundwater environment portrayed (north-north-east dipping, water <br />table grading to artesian conditions .as the distance to the outcrop <br />is increased) is consistent with the regional hydraulic and geologic <br />setting discussed earlier. Both potentiometric surface maps show the <br />water level contours, breaking at their confluence with Hayden Gulch <br />(discharge points). <br />Due to the limited recharge area above the discharge points on Hayden <br />Gulch, the primary discharge area for the coal aquifers is off the permit <br />area many miles to the north. A significant anomaly became apparent <br />on the potentiometric surface map of the lower coal aquifer. This <br />is a boundary effect (negative hydrologic boundary) which cuts off the <br />westward extension of the water level contours. This boundary is <br />identified through the location two dry wells LG-3 and LC-2. The <br />exact nature of this boundary is uncertain but is most likely due to <br />23 <br />_.. __ ,..~.- -u. r_ _ .. - - , ,..~ .,.~....._ .~___.~ <br />