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• <br />• <br />• <br />more than a few hundred yards before wedging out. None has been <br />correlated from the east to the west side of the syncline, a distance of <br />two to four miles". <br />These observations are consistent with drilling results as illustrated by <br />Exhibit 8, Geologic Information. Examination of drillhole logs and <br />resulting Geologic Cross-Sections (Maps 9 through 11), confirms the lack <br />of lateral continuity and demonstrates the variability of measured <br />groundwater levels. With limited lateral continuity, and the relatively <br />low permeability of the dominant siltstones and shales, both horizontal <br />and vertical hydraulic conductivity are low. Hydraulic conductivity for <br />the Vermejo formation was estimated at 10, to 10 feet per day by Willard <br />Owens Associates in their original hydrology report for Dorchester <br />presented in Exhibit 7, Hydrologic Information. The lower value was <br />verified by Western Engineers through a series of slug tests on monitoring <br />wells MW-10, 16 and 23 in October 1981 resulting in conductivity values <br />of 6 x 10' to 7 x l0a feet per day. <br />Given the low measured values of hydraulic conductivity and limited <br />lateral continuity of individual lithologic units within the Vermejo <br />Formation, it is reasonable to state that there are no known units which <br />can be considered as potential aquifers within this formation. This <br />statement is validated by the history of water use in this area. While <br />water from the Vermejo Formation has historically been utilized for <br />domestic and agricultural purposes, there is no history of conventional <br />water wells producing from this formation. Essentially all groundwater <br />use is from wells which pump water from abandoned and flooded underground <br />mine workings. Based upon the occurrence of groundwater resources in <br />these old workings and historic use, it appears that physical alteration <br />of stratigraphic zones within the Vermejo Formation is necessary to <br />provide consistent sustained well yields. Essentially all wells other <br />than those adjacent to the Arkansas River, having significant pumping <br />capacity, intercept and utilize groundwater resources stored in abandoned <br />underground mines. <br />2.04.7-3 <br />