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• creates large reservoir areas where variances in hydraulic pressure appear <br />to stimulate groundwater inflows and flooding of the abandoned mine <br />workings. <br />Groundwater occurrence and use also occurs within several of the strata <br />in areas immediately adjacent to the Arkansas River floodplain. This area <br />is well beyond the adjacent area for either the mine or loadout and water <br />occurrence is related to outcrop/subcrop conditions and possible hydraulic <br />connections between these units and the Arkansas River alluvium. <br />Additional details relative to the lithology of each of the stratigraphic <br />units is presented in Section 2.04.6, Geology Description. <br />Groundwater Levels. Given the constraints of limited lateral continuity <br />and relatively low hydraulic conductivity, groundwater levels within the <br />mine area are highly variable. <br />• Water levels recorded during exploration drilling activities as indicated <br />in Exhibit 8, Geologic Information, and on the Geologic Cross-Sections, <br />(Maps 9 through 11) vary significantly even within relatively short <br />distances. Localized variances in water levels reflect the occurrence of <br />perched groundwater reservoirs as previously discussed, the affects of <br />abandoned and flooded underground mine workings, and localized flows along <br />the hydraulic gradient. Given these considerations and the fact that <br />there are no continuous groundwater aquifers within the mine and adjacent <br />areas, no consistent piezometric surface exists in this area. <br />In addition to available drilling information, EFCI has monitored <br />groundwater levels in a series of monitoring wells within the mine area. <br />Groundwater levels within monitoring wells MW-10, 16 and 23 vary <br />appreciably given the relative proximity of these wells. There have also <br />been significant fluctuations in groundwater levels over time which cannot <br />be correlated to ongoing mining activity. Groundwater levels for five (5) <br />monitoring wells over the period 1979 through 1989 are graphically <br />• depicted by Figure 4, Monitoring Well Water Levels. <br />2.04.7-6 <br />