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2004 Update: Beginning July 8, 2004, the WRD and the USGS Geologic Discipline (GD) Eastern Earth Surface Processes Team return to the 2003 Elizabethtown drill site for supplemental drilling. The objective of this drill session is to define the lower stratigraphic units at this location and to date the stratigraphic units using the fossil record, and to determine the thickness of the aquifers.
The Elizabethtown drill site has been selected as an area of needed subsurface data. A significant aspect of this particular drill will be the collection of continuous core from the drillhole. The Eastern Services section of the Geologic Discipline (GD) will have their core recovery specialists obtaining continuous core from land surface to basement during this drill. The research interests of the study are designed in cooperation with the Southeastern Coastal Plain Project. This project is endorsed by the North Carolina Coastal Plain Earth Science Coalition, a multi-agency, multi-disciplinary group of collaborators, dedicated to the study of the hydrogeologic and stratigraphic framework of the N.C. Coastal Plain.
Drilling of an continuous core stratigraphic drill hole began on August 11, 2003 and was completed Tuesday, August 26, 2003. The Water Resource's primary focus is to understand the regional ground water flow system. Additional research objectives include developing a better understanding of the geohydrologic framework and acquiring primary data on the stratigraphic framework of the Coast Plain of North Carolina. The drilling effort is jointly funded by the Geologic and Water Resources Disciplines of the USGS, with additional support provided by the NC Division of Water Quality's Ground Water Section and the NC Geological Survey.
A monitoring well is being installed at the drill site in the Cape Fear Aquifer. The well site is in the Cape Fear watershed, about 6 miles southeast of Elizabethtown, North Carolina, in Bladen County. The aquifers encountered were the surficial aquifer, Black Creek aquifers, and the Cape Fear aquifer. Further subdivisions are now under consideration. Ground water is a source of drinking water in the area. It is also used for industrial and residential purposes. A Cape Fear piezometer (monitoring well will be completed sufficient to meet state regulations. The next step is to develop the well to remove any drilling mud that can be removed from the annular space, and to pump the aquifer to assure that there is hydrologic communication between the well and the aquifer. A workplan is under development for the design and installation of additional monitoring wells to be installed in the upper aquifers.
The location site for the core was selected for its stratigraphic and hydrogeologic significance. The site is located on an interfluve (elevation approximately 120 ft above MSL) on the southwestern side of the Cape Fear River, along strike with the Sugarloaf Landing outcrops (mileposts 65-66). The Tar Heel Formation of the Black Creek Group is exposed at Sugarloaf. Younger formations in the Black Creek Group, the Bladen and Donoho Creek Landing Formations are exposed at mileposts 60 and 50.2 (respectively) in the river banks. Theoretically this core hole, since it is located on an interfluve, should include the Cape Fear Formation, the Tar Heel Formation, the Bladen Formation, and the unconformities separating the units. The unconformity between the Tar Heel and Bladen has not yet been identified in outcrop. It is possible, albeit not probable, that the lower part of the Donoho Creek Landing Formation is present. The USGS will collect borehole geophysical well logs from the hole. WRD will install a piezometer in a lower aquifer to monitor water levels and water quality. The NC-DWQ-GWS will drill and install two shallow monitoring wells. The NCGS will provide electronic images of the core, log it and archive it for future studies.
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