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.

Cleaning It Up - State Remediation Initiatives Update

Emerging contaminants

Chemical Fixation of Priority Heavy Metals in Soil, Sediment, and Groundwater Using MetaFix™ Reagents

Patrick Hicks
High concentrations of heavy metals are found in many soil and sediment environments. At very high concentrations, heavy metals are known to create toxicity to microorganisms. Treatment approaches that rely on microbial process may not function well in an acutely toxic matrix because important processes such as carbon fermentation, oxygen consumption, and biological sulfate reduction can be significantly slowed or completely inhibited. The understanding of many metals removal mechanisms operative in soil and groundwater has advanced significantly over the past decade—thus, we are now in a better position to develop a new platform of effective metal remediation products.

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.

Facilitated Discussion: Which is the most critical regional groundwater challenge - Quality, Availability, or Proper Management?

Groundwater Sustainability Principles and Practices

Charles Job

Groundwater management, policy, and regulations

Wellntel Is Emerging as a Powerful Tool for Groundwater Monitoring Supporting Informed Management

Joseph Fillingham, Ph.D.
Growing and deepening groundwater information networks to improve understanding and management has always been challenged by the high cost of adding the next monitoring point. Wellntel completely changes that dynamic by introducing simple, accurate, consumer-priced groundwater level monitoring sensors and a cloud-based information system providing new insight at fractions of a cent per reading. This new system provides stakeholders such as well owners, well contractors, municipalities, and communities the ability to view graphical representations of their groundwater resource in a common access interface fostering a collaborative environment which builds understanding and new insights into groundwater change. By developing a clear baseline of groundwater dynamics, stakeholders are able to make informed and influential management decisions. Recognizing the opportunity to increase the density of data in local networks for model validation, early warning systems, and for guiding and enriching costly groundwater sampling projects, agencies, consultants, and other research organizations are adding Wellntel to their monitoring infrastructure. The utility of Wellntel for both stakeholder and research applications opens the door to new engagement between these groups, which is leading to powerful new opportunities for collaborative understanding and management. Wellntel is transforming the way groundwater monitoring can support both stakeholder management and academic research by expanding the geographic reach and temporal frequency of groundwater level measurements with a purpose-built, telemetry enabled system, and by maintaining data quality assurance and quality control using the cloud.


Groundwater sustainability

Assessment of Groundwater Quality of Atlantic Coastal Plain Aquifers, Aiken County, South Carolina

James E. Landmeyer, Ph.D.
Groundwater pumped from the Atlantic Coastal Plain (ACP) aquifers meets most of the potable and irrigation demands for Aiken County, but a comprehensive assessment of groundwater-quality conditions for Aiken County does not exist. This lack of an assessment of groundwater-quality conditions—even basic indicators such as pH, temperature, and dissolved oxygen—precludes county water managers and others from making informed decisions about where to place new wells (e.g., avoid areas where groundwater may contain high iron or radium isotope concentrations); how deep to drill wells; and what depth intervals should be screened to avoid in-well mixing of groundwater of different reduction/oxidation (redox) characteristics. As such, a comprehensive compilation of groundwater-quality data for Aiken County would be useful to water managers that want to minimize costs associated with groundwater treatment or others interested in groundwater quality.

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
Aiken County is located in South Carolina along the Fall Line and is bordered by the Savannah River on the west, Edgefield and Saluda Counties on the north, Barnwell and Orangeburg Counties on the southeast, and by Lexington County on the east. The 2014 population was estimated to be about 165,000 persons living in Aiken County, an increase of about 14 percent from 2000. Aiken County is the fourth largest South Carolina county by land area, about 1,073 square miles.

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.
Over the past several decades the Virginia Coastal Plain Aquifer System has experienced groundwater withdrawals totaling over 100 mgd, which are unsustainable through natural recharge to the system. This has resulted in continuous water level declines and has contributed to regional land subsidence and contamination from saltwater intrusion, compromising the continued use of the aquifers. In light of these challenges, Hampton Roads Sanitation District (HRSD) evaluated the costs and benefits of adding advanced water treatment to their existing wastewater treatment processes to provide more than 75 mgd of clean water to recharge the deep aquifers in Eastern Virginia, creating a sustainable groundwater supply while greatly minimizing discharges to Chesapeake Bay tributaries.

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
Concerns around groundwater management are on the rise for a variety of reasons. Groundwater is the source of drinking water for about half the total population in the United States, and long-term groundwater sustainability is in jeopardy. The future supply and availability of groundwater sources will depend on our implementation of sustainable solutions. Navigating these issues will require a challenging balance of priorities, including the location and allocation of capital as well as access to and vetting of appropriate expertise.

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
Classification of wetlands as surface water or groundwater-dominated ecosystems can affect their management, leading to mismanagement if misclassified. Wetlands commonly are misclassified as surface water–dominated ecosystems because of the abundance of standing and flowing surface water; however, groundwater commonly is the dominant water source.

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
Nitrogen loading to groundwater from surface activities has caused degradation of aquifer and surface water quality. Major research programs are in place to evaluate and manage nitrogen loading to regional estuaries including Chesapeake Bay. In Suffolk County, New York, an ambitious Comprehensive Plan was published in 2015 that addresses groundwater and surface water quality impairments resulting from nitrogen loading.

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
North Carolina is in the thick of administering a capacity use program in our coastal plain and is measuring some success. We maintain a statewide monitoring well network which helps us track overuse, drought and salt water encroachment concerns. We also are administering programs which require ground water monitoring for animal facilities, underground injection, non-discharge remediation, and NPDES permits. Coal ash site assessments and corrective action plans also come under our purview and are a hot topic. Lastly, we have a few ground water quality evaluations in progress which are examining background levels of contaminants to help us place coal ash and animal facilities in context.

Over pumping groundwater in the Coastal Plain: One states perspective

Craig Nicol
Virginia continues to see declining groundwater levels, increase in chloride concentrations, land subsidence, well interference, and loss of storage to its confined aquifers system in the Coastal Plain. With over a hundred years of research and monitoring in Virginia, documented concerns and trends lead to well capping laws, the creation of a Ground Water Management Act, and a regulatory framework for the establishment of management areas and permitting activities. However, 2010-2020 may be the most important decade for Virginia to decide on actions that result in long-term sustainability of groundwater in the Coastal Plain Aquifer System.

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
Channel sand deposits located at the base of shallow Coastal Plain aquifers form potential focal pathways for saline encroachment on freshwater resources. This study presents an example from Virginia Beach, Virginia where paleochannel deposits are incised into a buried barrier-island complex. Geologic and geophysical logs are correlated with groundwater ages to offer a revised hydrostratigraphic model of a buried barrier-island complex that includes sand aquifer heterogeneity associated with multiple depositional environments. Results from borehole nuclear magnetic resonance (NMR) are used to inform the hydrostratigraphic model by specifically assessing the variability in porosity and permeability of (1) fluvially derived paleochannel sands, (2) aeolian derived dune sands, and (3) wave-dominated nearshore shelly sands.

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.

Surface water/groundwater interaction

Groundwater Discharge to Streams in the Eastern United States

David L. Nelms
The importance of groundwater discharge to the understanding of quantity and quality of total streamflow along with impact to ecological habitats has long been recognized, yet seldom adequately quantified over large spatial and temporal scales. Hydrograph separation data from 849 stream gages in the Appalachian Plateaus were used to calibrate a Soil-Water-Balance model for the region and to assess spatial and temporal trends in groundwater discharge. Base-flow and runoff components of streamflow show close relations with annual precipitation and increased during the period of analysis from 1900 to 2011, especially since 1970. Increases in base flow account for most of the observed increases in mean annual streamflow, and the percentage of precipitation that resulted in base-flow discharge to streams varied annually by up to a factor of two. The evaluation has been extended into other physiographic provinces in the Mid-Atlantic states by inclusion of an additional 433 stream gages. Base flow is the dominant component of streamflow at approximately 65 percent of the sites in the eastern United States. The temporal distribution of base-flow index (ratio of base flow to streamflow) values from the complete data set (1,282 gages) shows the importance of base flow in sustaining streamflow in both wet and drought conditions, especially in watersheds underlain by carbonate rocks. The base-flow index, however, is independent of annual climate trends and indicates that changes in the components of streamflow are probably in response to shifts in seasonal precipitation or widespread changes in land-use practices.

The Flint MI Water Crisis: FlintWaterStudy's Journey With Flint Residents

Anurag Mantha

Welcome

William Alley, Ph.D.

Wrap Up