The Delaware Geological Survey released a new technical report titled “Southern New Castle – Northern Kent Counties Groundwater Monitoring Project: Results of Subsurface Exploration and Hydrogeological Studies,” which was prepared by A. Scott Andres, Thomas McKenna, and Changming He of the Survey, and former DGS employee Zachary Coppa. DGS Report of Investigations No. 82 documents the development of a detailed study of subsurface hydrogeology and geologic features, and interactions between aquifers and streams. The work was funded by the Delaware Department of Natural Resources and Environmental Control.

The report documents detailed observations and analyses made as a result of drilling and installing 22 new monitoring wells at eight locations, drilling of continuously cored test borings at five locations, downhole geophysical surveys at 15 sites, geotechnical and geochemical testing of sediment samples, and collection of several million water-level measurements. The new monitoring wells have been incorporated into the Delaware Groundwater Monitoring Network, and will be used for assessment of groundwater conditions for decades

Some of the key findings include - in the Blackbird State Forest area, geophysical logs, description of sediment, and hydraulic tests of new wells indicate that the Rancocas aquifer is thicker and more permeable than previously thought. Geophysical logs, sediment descriptions, water levels, and hydraulic tests of the Magothy Formation indicate that this unit only functions as an aquifer at one of the test sites. Evidence of faulting was observed in core samples collected from the Calvert Formation at all five coreholes as well as in the Manasquan and Shark River Formations in coreholes located in Smyrna. Regional and local pumping influences were evident at multiple sites. Hydraulic heads in the Rancocas and Mt. Laurel aquifers are near or below sea level in wells in the eastern third of the study area (east of Route 13). Long-term declining annual minimum flow and increasing annual maximum flow in more than 50 years of streamflow records at Blackbird Creek are consistent with long-term climate trends of increasingly severe droughts and storms.

The information in this report can be used to inform future scientists, business owners, the public, and resource managers about water resources and will be useful for planning future water supplies and wastewater disposal, and for management of water-dependent environmental resources.

The report fulfills part of the DGS’s mission to understand hydrologic systems and to advise, inform, and educate Delawareans about the results of such investigations so they can serve as a resource for scientists, engineers, planners, emergency managers, and the public.

Report of Investigations No. 82 is available in pdf format from the DGS web site at http://www.dgs.udel.edu/publications. For additional information, contact the Survey at (302) 831-2833 or via email at delgeosurvey@udel.edu.