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the last 10 years, and averaged -3.70 feet of decline in 2000-2001 (Roberts, 2001). <br />Most wells are drilled through the High Plains Aquifer and completed in multiple zones <br />below. For example, of the ten monitor wells reported to be completed in the High <br />Plains, six appear to have also penetrated the next underlying aquifer. Similarly, several <br />Dakota or Dockum wells may have been perforated in the overlying High Plains Aquifer. <br />More importantly, where the High Plains Aquifer directly overlies either of these <br />underlying aquifers, vertical movement of groundwater between the aquifers is likely. <br />Man-made vertical movement occurs in numerous cascading wells; i.e., the water in an <br />upper formation enters the well bore and cascades down the casing to the static water <br />level below. <br />6.3.3 Graneros Shale Aquitard <br />The Graneros Shale is a dense marine shale and an effective aquitard between the <br />overlying High Plains Aquifer and the underlying Dakota Aquifer. However, it is limited in <br />areal extent. As shown on the northern and western ends of cross-sections B—B', C—C', <br />and D—D', the Graneros appears locally to be a confining layer above the Dakota <br />Aquifer. The water level though is shown to be present above and below the Graneros <br />and as mapped (Map 3) indicates water table conditions. <br />6.3.4 Dakota Aquifer <br />The Dakota Aquifer includes the Dakota, Kiowa and Cheyenne formations. This <br />definition corresponds to the convention established by the Kansas Department of <br />Agriculture's Division of Water Resources and Kansas Geological Survey. It is practical <br />for use in the Basin for several reasons. As discussed in the geological section, <br />separating the lower Cretaceous formations can be difficult in drill cuttings and often <br />impossible from the driller's descriptions. The cross-sections distinguish the formations <br />as much as possible. Maps 5 and 6 are saturated thickness maps of the respective <br />aquifer members and are contoured on the bottom of the respective formations. <br />As shown in the cross-sections, the Dakota and the Cheyenne formations are dually <br />perforated in many wells. This study found only 21 monitor wells completed exclusively <br />in the Dakota or Cheyenne aquifer members, and an additional 22 with perforations in <br />the overlying High Plains or underlying Dockum (see Appendix D). Vertical flow of <br />groundwater between the Dakota and Cheyenne formations can be inferred from the <br />numerous neighboring wells completed in either formation of the aquifer and all having <br />rather consistent water levels. For example, in cross-section D—D' in T. 29-30 S., R. 48 <br />W., well #5116 is completed in the Dakota and well #5083 in the Cheyenne, but they <br />have effectively the same water -level elevation of 4534 feet above sea level. A similar <br />VI 9 <br />99-028.003\Phase 2 Report\Hydrogeology <br />