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B21D Using Numerical Models to Assess a Rapid Infiltration Basin System (RIBS), Cape Henlopen State Park, Delaware

B21D Using Numerical Models to Assess a Rapid Infiltration Basin System (Ribs), Cape Henlopen State Park, Delaware

The long-term performance of rapid infiltration basin systems (RIBS) and their potential impacts on the receiving environment have been previously unknown for Delaware. A variety of field experiments were conducted to characterize the geology and hydrogeology of a RIBS facility that has been in operation for more than 20 years at Cape Henlopen State Park. Pairs of standard monitoring wells and short-screened multi-level wells were used to evaluate the significance of small-scale vertical variability in water quality. A three-dimensional transient groundwater flow and contaminant transport model was constructed to simulate the groundwater mounding and the movements of nitrate-nitrogen (NO3--N) and orthophosphorus (OP) in the groundwater. In the numerical model, NO3--N was treated as a reactive species and denitrification was simulated with a first-order degradation rate constant. The major mechanism affecting OP transport in groundwater is sorption/desorption, which was simulated using a linear sorption isotherm. Simulated concentrations reasonably fit observed concentrations of NO3--N and OP in both standard wells and multi-level wells. The calibrated model predicts that with a denitrification rate of 0.006/day and a distribution coefficient of 4×10-7 L/mg, 63 percent of the reduction in the mass of NO3--N is attributable to denitrification, and more than 99 percent of OP is detained in the aquifer due to sorption on subsurface solids. However, the long-term operation of RIBS has led to a reduction of the sorption capacity of subsurface solids for phosphorous, resulting in significant concentrations of OP in groundwater adjacent to RIBS.

Delaware Geological Survey Issues Report on Hydrogeologic Impacts of Rapid Infiltration Basin Systems

The Delaware Geological Survey released a new technical report entitled “Hydrogeology of a Rapid Infiltration Basin Systems 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, and Müserref Türkmen of the Izmir Water and Sewerage Administration, Turkey, and DGS Bulletin 21B documents the results of a detailed study of groundwater and hydrogeology at a rapid infiltration basin system.

B21A Evaluation of Wastewater Treatment Options Used in Rapid Infiltration Basin Systems (RIBS)

This technical report evaluates several aspects of potential environmental risks, use, and regulation of rapid infiltration basin systems (RIBS) in Delaware. The report reviews and compares regulations regarding RIBS from Delaware, Florida,North Carolina, New Jersey, Maryland, and Massachusetts. Influent and effluent samples from ten advanced wastewater treatment systems that operate in conjunction with RIBS were collected and analyzed. Effluent data obtained from the Non-Hazardous Waste Sites database provided by the Delaware Department of Natural Resources and Environmental Control and other states were assessed. Performance evaluations of the treatment processes that discharge to RIBS were ascertained from the exceedance of concentrations of regulated pollutants in effluent samples.

Although RIBS technology has the potential to be a beneficial alternative to surface discharge and a means for groundwater recharge, this technology is appropriate only if the adverse environmental impacts are minimized. Overall operation and maintenance practices play important roles in the performance of treatment plants. The most common and serious problems associated with treatment plants located in Delaware and neighboring states are high nutrient and pathogen concentrations in the effluent. In Delaware, the discharge of poorly treated effluent to RIBS creates a risk of nutrient and pathogen contamination in the receiving water body, the shallow Columbia aquifer. Years of application of treated effluent with high nutrient, pathogen, and organic content to RIBS will result in significant risks for the environment and public health.

DGS presentation to Delaware River Basin Commission Water Management Advisory Committee on Groundwater Monitoring

Scott Andres presented an invited talk “Update on Groundwater Monitoring in Delaware” at the Groundwater Management Workshop sponsored by the Delaware River Basin Commission (DRBC) in West Trenton, NJ on October 22, 2015.

DGS Presentation on Groundwater to Clean Water Task Force

Presentation on Groundwater to Clean Water Task Force by staff member Scott Andres

DGS welcomes James D. Hanes to UD NEWRNet project

Environmental Sciences student James Hanes (BS 2016) has accepted a Water Resources Center Undergraduate Internship for Fall 2015 to work with A. Scott Andres of DGS, and William Ullman and Christopher Main of the School of Marine Science and Policy at the University of Delaware. James will work on high-frequency environmental data collected by the North East Water Resources Network (NEWRNet) project (, an NSF-EPSCoR funded project that includes investigators and students from the Universities of Delaware, Rhode Island, and Vermont.

Project Update: NEWRnet - North East Water Resources Network

Monitoring station at Coursey Pond outlet

Infrastructure that will support the NEWRNet water quality monitoring station was installed at the main outflow of Coursey Pond on the fish ladder on April 23, 2014.

NEWRnet - North East Water Resources Network

NEWRnet study sites
Project Contact(s):

The North East Water Resources (NEWRnet) consortium of EPSCoR jurisdictions of Delaware (DE), Rhode Island (RI), and Vermont (VT) will create an advanced sensor network in watersheds for gathering high-frequency, spatially-extensive water quality and quantity data and a network of lab and field-based experiments and agent-based models to investigate how to align sensor data and their visualization with utilization by stakeholders. DGS is participating in the watershed sensing network by installing and operating a nitrogen and organic carbon sensor and stream discharge monitoring station in the Murderkill River watershed, and collaborating with the project team to interpret results.

EPSCoR Track 2 - New grant from NSF EPSCoR will establish water resources network

Geographer Dan Leathers (standing), a lead principal investigator on the Delaware-Rhode Island-Vermont EPSCoR RII Track-2 grant, works with colleagues John Callahan of the Delaware Geological Survey and Kevin Brinson of the Delaware Environmental Observing System to download data from an environmental sensor to a laptop computer for analysis.

The Delaware Experimental Program to Stimulate Competitive Research (EPSCoR) is a partner in a three-year, $6-million grant from the National Science Foundation through its EPSCoR Research Infrastructure Improvement Track-2 program.

The grant program supports research by consortia of EPSCoR jurisdictions. Through this award, Delaware will join with the EPSCoR programs in Rhode Island and Vermont to form the North East Water Resources Network (NEWRnet). Two million dollars of the grant will go to each of the three states involved.

Assessing Potential Impacts of a Wastewater Rapid Infiltration Basin System on Groundwater Quality: A Delaware Case Study

DGS staff member A. Scott Andres along with J. Thomas Sims of the University’s Department of Plant and Soil Science have had a paper “Assessing Potential Impacts of a Wastewater Rapid Infiltration Basin System on Groundwater Quality: A Delaware Case Study” published in the Journal of Environmental Quality. This paper is the latest technical report from a DGS-led project “Evaluation of Rapid Infiltration Basin Systems (RIBS).” Four additional reports on this project are nearing release in the DGS bulletin series. Information about this project can be found at:

Finding faults - Delaware Geological Survey discovers evidence of past earthquakes

Delaware Geological Survey scientists found slickensides in core samples indicating faults in northern Delaware.

Delaware Geological Survey (DGS) scientists have uncovered hard proof of faults in northern Delaware, indicating the occurrence of earthquakes millions of years ago.

Monitoring our water - Delaware Geological Survey improving groundwater monitoring efforts with new wells, sampling

Scott Andres examines sediment samples extracted from more than 500 feet underground for clues about the amount and quality of water available in central Delaware.

Delaware Geological Survey improving groundwater monitoring efforts with new wells, sampling. Scientists are digging for answers about the amount and quality of water available underground in central Delaware, where ongoing development will put increasing demands on water supplies in the coming decade.

The Delaware Geological Survey (DGS) is installing 7,700 feet of wells at eight sites in southern New Castle and northern Kent counties to improve groundwater-monitoring efforts, supported by a $600,000 grant from the Delaware Department of Natural Resources and Environmental Control (DNREC). Groundwater is the primary source of drinking water south of the Chesapeake and Delaware Canal, and populations there are projected to continue expanding.

DNREC raises capital request - Sixfold hike includes beach, water projects

More money would go to projects that make Delaware cleaner, greener and safer under a mostly no-growth budget outlined Monday by the Department of Natural Resources and Environmental Control. Agency Secretary Collin P. O'Mara asked the Office of Management and Budget for about $35.2 million in general funds for the fiscal year that begins July 1, with health care costs accounting for most of the nearly $2 million increase from the current year.

OFR16 Geologic and Hydrologic Aspects of Landfills

OFR16 Geologic and Hydrologic Aspects of Landfills

In the United States more than 3.5 billion tons of solid waste are generated annually. Of this, more than 2 billion tons are agricultural waste, such as manure and crop waste. Almost 300 million tons are generated by commercial and industrial activities and municipalities, and another 1.1 billion tons are attributed to various mining operations (Vaughan, 1969). Increasing amounts of solid waste have had detrimental effects on environmental quality. It has become necessary to reprocess and reuse some, and to provide safe and environmentally acceptable ways of disposing of the remaining waste in properly constructed landfills. Pollution brought about by improperly constructed landfills may be very severe. For example, the contaminants generated by the waste at the old, abandoned Army Creek Landfill, New Castle County, Delaware, were so widespread that the situation received national attention. General and sincere concern expressed by many citizens of our State has prompted the Delaware Geological Survey to prepare this report. The report explains the functioning of a landfill, problems improperly constructed landfills may cause, and the geologic and hydrologic aspects that have to be considered in selecting a suitable disposal site for solid waste. The report does not contain discussions of other important factors, such as social impact, transportation, and specific health hazards, that must also be considered.

OFR44 Storm-Water and Base-Flow Sampling and Analysis in the Delaware Inland Bays Preliminary Report of Findings 1998-2000

OFR44 Storm-Water and Base-Flow Sampling and Analysis in the Delaware Inland Bays Preliminary Report of Findings 1998-2000

This report provides initial research results of a storm-water and base-flow sampling and analysis project conducted by the University of Delaware College of Marine Studies (CMS) and the Delaware Geological Survey (DGS). Base-flow samples were collected from six tributary watersheds of Delaware’s Inland Bays on 29 occasions from October 1998 to May 2000. Water samples were filtered in the field to separate dissolved nutrients for subsequent analysis, and a separate sample was collected and returned to the laboratory for particulate nutrient determinations. On each sampling date, temperature, conductivity, pH, and dissolved oxygen concentrations were determined at each sampling station. Stream discharge measurements at each of these sites were made by the U.S. Geological Survey (USGS) under a joint-funded agreement with the Delaware Department of Natural Resources and Environmental Control (DNREC) and the DGS. Together, the nutrient and discharge data were used to determine the total and unit (normalized to watershed area) nutrient loading from base flow to the Inland Bays from each of these watersheds on a quarterly and annual basis. At the same six stations, storm water was collected during eight storms from May 1999 to April 2000. Storm-water loadings of nutrients from each watershed were calculated from the concentrations of nutrients in water samples collected at fixed time intervals from the beginning of the storm-water discharge period until recession to base flow. These data provide DNREC with a more complete picture of the seasonal dependence of nutrient loading to the Bays from which to establish goals for total maximum daily loads in the Inland Bays watershed.

B11 Ground-Water Resources of Southern New Castle County Delaware

B11 Ground-Water Resources of Southern New Castle County Delaware

Southern New Castle County has a land area of 190 square miles in north-central Delaware. It is predominantly a rural area with a population of about 9,000 people who are engaged chiefly in agriculture. By and large, the residents are dependent upon ground water as a source of potable water. This investigation was made to provide knowledge of the availability and quality of the ground-water supply to aid future development. The climate, surface features, and geology of the area are favorable for the occurrence of ground water. Temperatures are generally mild and precipitation is normally abundant and fairly evenly distributed throughout the year. The topography of the area is relatively flat and, hence, the streams have low gradients. The surface is underlain to a considerable depth by highly permeable unconsolidated sediments that range in age from Early Cretaceous to Recent.

DGS issues report on well water quality survey

OFR48 Results Of The Domestic Well Water-Quality Study

The Delaware Geological Survey (DGS) at the University of Delaware has released a new technical report that documents technical aspects of an intensive survey, review and analysis of existing ground-water quality data obtained from samples collected from more than 200 shallow domestic and small public wells to determine the extent to which toxic and carcinogenic compounds are present in shallow ground water.