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points where the data were taken are also shown on Exhibit 2.5-I I. The piezometric surface in the central and southern portions of the Edna Mine has been influenced ~ by mining and data from previous studies discussed above are no longer applicable. For this reason, the piezometric surface in the vicinity of the Moffat Area only is shown. The data available are insufficient to determine The location of the line of intersection of the piezometric surface and the top of the Wadge coal (zero potential line) with certainty. However, observations other than those shown in Table 2.5-12 were used to locate The zero potential line shown in Exhibit 2.5-I I. Specifically, two wells were drilled, but not cased, on the approximate east-west line through 05-03- 0005 and 05-01-0010. Both of these wells (IA and 05-01-0009) are located between Trout Creek and 05-01-0010. Well IA was drilled to a depth of 99 feet (elevation 6,981) and produced water. Well 05-01-0009 was drilled To a depth of 119 feet' (elevation 7,121) and was dry. The zero potential line must be located between these , two wells, therefore. It is estimated that the elevation of the zero potential line 1 in the southern end of the Moffat Area is between 7,050 and 7,100 feet. ~.3+ ~w#.r]y~W o e°`IGI"o"f'1"dT' I Arev w^"°'il'(`in" lc uc' se ome i"" n'fT~SvS: "°~ On an east-west line through well IC, it is expected that the intersection of The piezometric surface with the Wadge occurs in the elevation range of 7,020 to 7,070 feet. In the area north of IC the elevation of the zero potential line should decrease gradually to about 6,900 feet aT the point where Trout Creek cuts through the Wadge approximately 5/8 mile north of The south line of Section 25. In well 05- 01-0004, the Wadge is at elevation 7,022 feet and is above the zero potential line. The water surface elevation in well 05-01-0010 casts some doubt on the above interpretation. A substantial column of water stands in this well and it is located well updip from the estimated zero potential line. The occurrence of water in this well is not understood, but may be due to a local perched aquifer. Other holes (a total of 10) terminating at elevations above the estimated zero potential line were essentially dry. Relative to the assessment of the groundwater on the east side of Trout Creek in the Moffat Area, it is important to note that this area is an immediate northward extension of the existing Edna Mine. None of the data collected in This study suggest that conditions in the to-be-mined portion of The Moffat Area will be significantly different from those encountered on the north portion of the existing Edno Mine. fJo '~ significant ground water inflows were experienced in the upslope pits of the existing 2.5-48