The Delaware Geological Survey released a new technical report entitled “Groundwater Quality and Monitoring of Rapid Infiltration Basin Systems, Theory and Field Experiments at Cape Henlopen State Park, Delaware” which was prepared by A. Scott Andres and Changming He of the Delaware Geological Survey, Edward Walther of the South Water Management District, Florida, Müserref Türkmen of the Izmir Water and Sewerage Administration, Turkey, and Anastasia Chirnside and William Ritter of the University of Delaware. DGS Bulletin 21C documents the results of a detailed study of groundwater quality at a rapid infiltration basin system.
A rapid infiltration basin system (RIBS) consists of several simple and relatively standard technologies; collection and conveyance of wastewater, treatment, and discharge to an unlined excavated or constructed basin. By design, the effluent quickly infiltrates through the unsaturated or vadose zone to the water table. During infiltration, some contaminants may be treated by biological and/or geochemical processes and diluted by dispersion and diffusion.
The hydrogeologic framework of Cape Henlopen State Park (CHSP), Delaware was characterized to document the hydrologic effects of treated wastewater disposal on a rapid infiltration basin system (RIBS). Characterization efforts included installation of test borings and monitoring wells; collection of core samples, geophysical logs, hydraulic test data, groundwater levels and temperatures; testing of grain size distribution; and interpretation of stratigraphic lithofacies, hydraulic test data, groundwater levels, and temperature data.
This report presents a conceptual model of groundwater flow and the effects of nitrate (NO3-) loading and transport on shallow groundwater quality in a portion of the Indian River watershed, eastern Sussex County, Delaware. Three-dimensional, numerical simulations of groundwater flow, particle tracking, and contaminant transport were constructed and tested against data collected in previous hydrogeological and water-quality studies.
To understand the effects of projected increased demands on groundwater for water supply, a finite-difference, steady-state, groundwater flow model was used to simulate groundwater flow in the Coastal Plain sediments of southern New Castle County, Delaware. The model simulated flow in the Columbia (water table), Rancocas, Mt. Laurel, combined Magothy/Potomac A, Potomac B, and Potomac C aquifers, and intervening confining beds.
Scientists study flow of groundwater into bays. Results may help track pollution.
On a small, homemade barge, built from the skeleton of an old ship, a gray slurry of bay bottom sand flows out of a pipe into a bucket. Two scientists, a well driller and two student interns drill a hole in the floor of the Indian River Bay. They’ll install a very long pipe into the hole and use it to monitor groundwater – how much flows into the bay, how salty it is and how many nutrients it carries with it.
A quasi three-dimensional model was constructed to simulate the response of the Piney Point and Cheswold aquifers underlying Kent County, Delaware to ground-water withdrawals. The model included the Magothy, Piney Point, Cheswold, and unconfined aquifers, and was calibrated using historical pumpage and water-level data. Model calibration was accomplished through the use of both steady-state and transient-state simulations.
The unconfined aquifer in central and southeastern Delaware occurs as a southward-thickening blanket of fine to coarse sand, and is recharged almost totally by precipitation and discharge is principally by seepage to streams, bays, and the ocean.