Groundwater from the Mountains to the Sea in the Central Atlantic Region: Alphabetical Content Listing
Addressing Time in Communicating Groundwater Science
William Alley, Ph.D.
Emerging contaminants
Chemical Fixation of Priority Heavy Metals in Soil, Sediment, and Groundwater Using MetaFix™ Reagents
Patrick Hicks
Hence, in toxic environments treatment reagents that do not depend entirely on microbial activity but rather combine reduction with adsorption and precipitation of heavy metals are advantageous. MetaFixTM reagents represent an entirely new family of products for treatment of soil, sediment, industrial wastes, and groundwater contaminated with heavy metals. Treatment mechanisms based on iron, iron sulfides, and other iron-bearing minerals have significant advantages due to lower solubility and greater stability of iron-bearing mineral precipitates formed with heavy metals.
The approach used in these new reagents is to create an effective blend of reducing agents, reactive minerals, mineral activators, catalysts, pH modifiers, and adsorbents for either ex-situ or in situ applications. In situ reactive zones can be constructed to prevent migration of heavy metals in groundwater. Excavated soils or dredged spoils containing high levels of TCLP/SPLP metals can be quickly treated and stabilized before final disposal. MetaFix reagents can also be directly delivered into or onto sediments for in situ stabilization of heavy metals and thereby reduce exposure to aquatic life. Laboratory and field results showing reduction in potential leaching of key metals will be presented.
Groundwater management, policy, and regulations
Wellntel Is Emerging as a Powerful Tool for Groundwater Monitoring Supporting Informed Management
Joseph Fillingham, Ph.D.
Groundwater sustainability
Assessment of Groundwater Quality of Atlantic Coastal Plain Aquifers, Aiken County, South Carolina
James E. Landmeyer, Ph.D.
In Fiscal Year 2015 the U.S. Geological Survey, in cooperation with Aiken County, Breezy Hill Water and Sewer Company Inc., Gilbert-Summit Rural Water District, and Montmorenci-Couchton Water and Sewer District, started a three-year project to investigate the availability of the groundwater resources of Aiken County. A major component of the project is to develop a groundwater-flow model of the ACP beneath Aiken County. Because groundwater availability is dependent upon water quality, and water-quality characteristics can be useful during model calibration, the study will provide these data in two ways. First, existing water-quality data will be compiled, and second, we will sample multiple public-supply wells across the county for basic physical properties and chemical composition of the groundwater. At select wells, additional water-quality parameters such as inorganics, radionuclides, and volatile organic compounds also will be sampled and analyzed.
Development and Application of a Groundwater Flow Model of the Atlantic Coastal Plain, Aiken County, South Carolina
Bruce G. Campbell
Most of the potable water produced in Aiken County, with the exception of North Augusta, is supplied by groundwater produced from the various Atlantic Coastal Plain (ACP) aquifers underlying the county. The ACP aquifers underlying Aiken County are very productive and generally contain high-quality groundwater that requires little treatment prior to use. The reliance on groundwater by Aiken County has increased steadily since the 1950s, but it is unknown if this withdrawal of groundwater will affect the current or future availability or quality of groundwater in Aiken County. Irrigated agriculture acreage is expanding in Aiken County, resulting in an increased demand on groundwater resources.
The primary objective of the assessment of the groundwater availability for Aiken County is to develop a groundwater-flow model that can be used by Aiken County water utilities to manage current and projected reported and unreported demands on the groundwater resource and to ensure the highest quality of groundwater. This objective can be discretized into four tasks, listed here in order of implementation: (1) develop a state-of-the-science groundwater-flow and management model; (2) calculate the water budget for the Aiken County area; (3) document the general water-quality characteristics for public-supply wells across Aiken County; and (4) assess the occurrence of chemical contamination in selected public-supply wells.
Groundwater Sustainability Through Indirect Potable Reuse: Concept Feasibility Project in Southeastern Virginia
Daniel Holloway, P.G.
HRSD conducted a concept feasibility study to evaluate: (1) potential advanced treatment processes, (2) the suitability of the aquifer for recharge, (3) benefits to the aquifer system, (4) geochemical compatibility of the treated water with the native groundwater and aquifer, and (5) high level cost estimates. Three advanced water treatment flow sheets were evaluated for implementation following HRSD’s existing treatment processes: (1) reverse osmosis-based train, (2) nanofiltration (NF) based train, and (3) BAC/GAC based train. Geochemical compatibility was modeled comparing water quality from each treatment train with the native groundwater and aquifer mineralogy. Groundwater flow models were used to evaluate the hydraulic capacity of the aquifer system and the sustainability of withdrawals following recharge. Capital and O&M costs were prepared for each of the treatment processes and associated facilities.
The treatment trains produce high quality water and include multiple barriers for pathogen and organics removal; however, only the BAC/GAC and NF treatment processes produce water qualities compatible for injection without significant post-treatment additives. Groundwater flow modeling indicates significant regional benefit to the aquifer system. Recharge provides a sustainable source for permitted groundwater withdrawals and may also slow land subsidence and prevent saltwater intrusion.
Overcoming Long-Term Challenges in Groundwater Sustainability
Jason Wuliger
Whether controlling contaminants from entering groundwater sources, preventing saltwater intrusion, replenishing water in streams and lakes, or confronting our lowering water table, regions across the United States are struggling with how to provide clean water to communities for domestic supply and irrigation without harming or overstressing groundwater sources. In the Atlantic Coastal Plain in particular, water is being pumped from groundwater supplies for domestic use, but being discharged into saltwater bodies. Thus, groundwater bodies have decreased and saltwater intrusion continues to move inland. Every region and community has a unique set of needs for managing groundwater and faces constantly changing conditions―environmental as well as financial and political. Communities need tools that help them develop a customizable approach to gaining expertise and financial support based on their unique circumstances.
At times groundwater problems can seem insurmountable, but there are tools, expertise, and funding opportunities for water challenges available. Funding is currently being allocated for research on how water conservation, contamination, aquifer recharge, reuse strategies, and water supply management affect groundwater. The ability to pay for and develop needed solutions and research can take many forms, but solutions are accessible, and getting the right products and expertise for communities’ unique conditions is key.
Groundwater-dependent ecosystems
Groundwater Management of an Atlantic Coastal Plain Forested Peatland: The Great Dismal Swamp
Gary Speiran
The Great Dismal Swamp National Wildlife Refuge (a forested peatland in the Atlantic Coastal Plain of Virginia and North Carolina) could be classified as a surface water–dominated ecosystem because of a 144-mile ditch network and small streams that flow across the Suffolk Scarp into the swamp; however, the swamp actually is a groundwater-dominated ecosystem. Groundwater is derived from upland flow from west of the scarp that discharges into the swamp at the base of the scarp and recharge to the surficial aquifer by direct precipitation across the swamp. The surficial aquifer consists primarily of peat that can have a thickness as great as 15 feet. Porosity and permeability of the peat, however, decrease abruptly below a depth of 1.5 to 2 feet so that storage and transport of most groundwater typically is limited to the upper peat. Because the water-table depth typically is less than 3 feet and the upper peat is permeable, recharge is rapid. Groundwater flows and discharges along two pathways: (1) discharge to the atmosphere as evapotranspiration by the forest vegetation, and (2) lateral flow and discharge to the ditches. Discharge to ditches historically has created drier than natural conditions across the swamp, altering forest-species composition, increasing the risk of wildfire, and causing decomposition of peat to release carbon dioxide. To manage the swamp as a groundwater-dominated ecosystem, the U.S. Fish and Wildlife Service is installing and managing water-control structures on the ditches to maintain groundwater levels.
Keynote: The Challenges of Total Radium in Groundwater: Its Sources and Occurrence, Fate, and Threats
James E. Landmeyer, Ph.D.
Nitrate and pesticides
From TMDLs to PRBs Using Groundwater Models to Evaluate Nitrogen Management Strategies
Dan O’Rourke, PG
Groundwater models are being utilized to better understand the impact of nitrogen reduction strategies such as sanitary sewering. As part of a total maximum daily load (TMDL) for nitrogen for the Forge River Estuary, nitrogen loading models have been coupled with groundwater models to simulate the fate and transport of parcel-specific nitrogen loading. Where development opportunities exist within Suffolk County, groundwater modeling analyses were completed to evaluate the impact of housing density on shallow water supply wells. Utilizing groundwater models allows for a better understanding of the impact of historic land uses on aquifer nitrogen concentrations and ultimate discharge to receptors (supply wells or surface water).
Permeable Reactive Barriers (PRBs) are designed to intercept and remediate groundwater contaminant plumes. PRBs have generally proven to be an effective and sustainable technology, with recent applications demonstrating their effectiveness at reducing elevated concentrations of nitrate in groundwater. Groundwater models are being used to help design PRBs in Suffolk County by evaluating the zone of capture and anticipated nitrate load reduction.
In both of these applications, and in most groundwater-based analyses, the slow movement of groundwater and the highly dynamic nature of aquifer withdrawals for water supply result in very long travel times and indirect pathways from the source(s) of the nitrogen loading to discharge points. For this reason, it is important municipalities and regulators understand the value groundwater models provide in making major infrastructure decisions.
Panel: What's the Latest in State Groundwater Management Plans
From Capacity Use to Coal Ash
Nat Wilson
Over pumping groundwater in the Coastal Plain: One states perspective
Craig Nicol
Since 2007, the Virginia Department of Environmental Quality has been actively implementing goals developed through strategic planning to reduce current use, promote greater water conservation measures, and increase hydrogeologic understanding and modeling capabilities that assist or promote innovative ways to manage groundwater in Virginia.
As a result of those initial actions, the Virginia Department of Environmental Quality has now embarked on the next step, the Virginia Coastal Plain Groundwater Initiative. The initiative includes modeling activities to evaluate the optimization of proposed reductions, an investigation into the economic impacts associated with those proposed reductions, and a 2015 legislative action resulting in the creation of the Eastern Virginia Groundwater Management Advisory Committee. The committee has been tasked with examining options for developing long-term alternative water sources and management structures along with other actions that may enhance the effectiveness of groundwater management.
Saltwater intrusion
Porosity, Permeability, and Salinity in Pliocene and Pleistocene Aquifers, Outer Coastal Plain in Virginia
Kurt J. McCoy
Salinity of these shallow aquifers in Virginia Beach is evaluated using the cross-plot method of logged porosity and resistivity values. The cross-plot method is of potential use to estimate water resistivity (Rw) in freshwater formations where assumptions of Archie’s law are invalid. The range of estimated Rw resulting from use of NMR and neutron porosity values in screened intervals are compared with field samples of water quality to evaluate the utility of the cross-plot method to estimate water quality in typical shallow Coastal Plain aquifers along the Eastern and Gulf Coasts of the United States.