2018 Groundwater Week: Alphabetical Content Listing

Advanced Methods for Monitoring and Sampling in Karst Groundwater Systems

Jason Polk, Ph.D., James Shelley and Rachel Kaiser

Airborne Electromagnetic Surveys for Hydrogeologic Frameworks and Groundwater Management

James Cannia, BSc, Jared Abraham, M.Sc. and Ted Asch, Ph.D.

Anything Else Groundwater

A Five-Year Estimation of Wasted Potable Landscape Irrigation Water, Orange Crest-Mission Grove Area (OCMGA), Riverside CA

Thomas Deane, CHg, PG, RG
A potential large-scale field lab has been identified within the fully-developed Orange Crest/Mission Grove area (OCMGA) of Riverside CA that can be used to verify the efficacy of residential landscape water-saving devices. Anthropogenic (potable) surface water runoff rates of forty radially-oriented drainages were annually estimated from 2008 to 2012. Visual estimates were conducted during the afternoon hours during each July to reduce the influence of morning mass-residential landscape irrigation and each preceding rainy season, to collect daily surface water “base flow” data. The OCMGA is underlain by a relatively thin veneer of alluvium overlying shallow crystalline bedrock, into which two main paleodrainages underlying ~116 AC had been eroded. This presentation focuses on the two paleodrainages and their terminal drainages.

Instead of percolating downward to an underlying regional aquifer, the runoff is directed laterally outward via the paleodrainages as surface water. Thus, with proper instrumentation, this ideal hydrogeologic setting would allow one paleodrainage area to be used to en masse test the effectiveness of emerging water-saving devices and the other area to be used as a 2005-buildout “control”, by comparing before/after drainage runoff volumes.

Assuming that OCMGA landscape irrigation occurs 365 days/year, the combined runoff volumes from these drainages for 2008/2009/2010/2011/2012 were approximately 32/40/48/48/40 AFY. These volumes correspond to (state-wide) 2008/2009 drought conditions, a 2010/2011 increase in precipitation, and a 2012 decrease in precipitation. Thus, the averaged 2008/2009/2012 volume of 37 AFY from only ~116 AC may represent the “base flow” OCMGA runoff landscape irrigation volume, equivalent to the annual needs of 74 households. Using all OCMGA drainage volume data and assuming that the OCMGA represents typical irrigation practices/devices, extrapolation using 2010 California Department of Finance census data indicates that approximately 67,739 AF of potable water may annually be lost to landscape over-irrigation within southern California

Flow of Groundwater through North Slope, Alaska Gravel Pads

Ori Miller
Since the beginning of oil production in Alaska, oil companies constructed facilities all across the North Slope of Alaska to access the numerous crude reserves on the North Slope. Production in some of the older fields is on the decline; however exploration in newly opened areas of the North Slope is resulting in the discovery of new reserves. The result is that in the coming decades the old sites will need to be decommissioned as production transitions to new sites. New sites will also need to be designed and constructed. To guard against thawing permafrost and associated thaw subsidence, the oil facilities in the Arctic are constructed on gravel pads placed on top of the existing arctic tundra. Gravel pad thicknesses can range from around 0.6 m to as much as 1.5 m. As the oil companies transition to the new sites the question arises, what should be done with vacated gravel pads? By Alaska State constitution, the natural resources of Alaska belong to the state but the state legislature my lease out land and mineral rights to private entities. Oil companies on the North Slope have historically conducted operations through these leases given by the legislature. The leases require that once resource extraction operations are completed, the facilities must be decommissioned and the sites restored. This original lessee retains this responsibility (regardless if the original lessee has sold or transferred the lease to another entity).

The construction of gravel pads essentially destroys underlying arctic tundra. In undisturbed areas in the Arctic, the tundra itself creates an incredible insulating layer that limits the seasonal thaw depth to around 0.5 m. Removal of this layer causes thaw depths to greatly increase impacting the stability of the ground and the hydrology of the surrounding area. Because of this impact, other possible restoration techniques are being considered, such as vegetating and leaving the pads in place. A major aspect of the gravel pad decommissioning and restoration process is understanding the hydrology in areas where gravel pads exist, in particular, groundwater flow through the gravel pads. Because of the unique conditions in the Arctic, groundwater flow through these gravel pads is not well understood. The purpose of this project is to develop this understanding. We use field measurements and an associated groundwater model to examine the flow of groundwater through gravel pads and the driving forces for this flow. The gravel pad used for this study is located in Prudhoe Bay and is part of the pad constructed for the first production well in Prudhoe Bay. The results from this field study and model will assist engineers and environmental scientists in better understanding the groundwater flow to aid in the decommissioning and restoration process and help inform decision-making in regards to the future of the pads.

Quantifying Groundwater Evapotranspiration with Remote Sensing for the Humboldt River Basin, NV

Matt Bromley, M.S.
The Desert Research Institute in cooperation with the USGS and the Nevada Division of Water Resources is currently evaluating groundwater discharge via evapotranspiration from phreatophyte shrubs in the Humboldt River Basin, NV. The overarching goal of this work is to improve the modeling of groundwater for the purposes of evaluating the interplay between groundwater and surface water.

Accurate estimates of groundwater ET (ETg) are essential to developing groundwater budgets, modeling boundary conditions, and ultimately constraining model calibration of aquifer properties (i.e. non-uniqueness between recharge, transmissivity, and discharge). Methods used to estimate ETg are often based on intensive field based micrometeorological measurements, assumed or fixed rates, or a combination of remote sensing and empirical relationships based on past measurement studies.

The approach used in this study uses a regression based on enhanced vegetation index (EVI) calculated from remotely sensed optical data acquired by the Landsat series of satellites, along with precipitation and evaporative demand in the area of interest. This regression was developed through the evaluation of 40 site years of micrometeorological data collected at 26 unique sites, primarily located within phreatophyte areas of Nevada. Google Earth Engine (GEE), a massively parallel, cloud-computing platform, was used to apply this method to 30 years of Landsat images and climate archives, in order to produce annual estimates of rates and volumes of ETg over the entire Humboldt River Basin. Because volume calculations of ETg are sensitive to estimates of phreatophyte area, an evaluation was conducted to determine the accuracy of previously defined phreatophyte boundaries. This review was performed through a combination of field evaluations and an examination of aerial imagery and optical and thermal Landsat data.

This presentation will describe methods used to quantify ETg in the Humboldt River Basin, preliminary results, and the relevance of the data to ongoing groundwater modeling efforts.

Remediation to Research: Training Future Hydrogeologists--A Repurposed Geoprobe to Assess an Alluvial Aquifer

Wayne Hamilton, PE, PG, Research Faculty
Baylor University purchased a used Geoprobe drill rig from a consulting firm in Chicago that was used to assess leaking underground storage tank sites. The Geoprobe was repurposed to support education and academic research by providing a variety of subsurface data. This presentation is about our academic Geoprobe use learnings to supplement our teaching and research in the Brazos River Alluvium aquifer. Our Geoprobe learnings are in two broad areas: 1) geologic education and 2) equipment ownership. The education learnings are related geologic data gathering such as aquifer sediment coring, installing monitor wells, and obtaining discrete vertical groundwater chemistry data. This geologic data collection is the foundation of our education and research activities. Having control of equipment use, transport, and timing are the keys to effective geologic data gathering in a busy academic schedule. Also, students and faculty gain Geoprobe field experience and education from laboratory exercises and graduate students obtain data for their research. The classroom education is supplemented by Geoprobe field exercises such as: sediment description and monitor well installation. Hence the Geoprobe usage leads to training the next generation of hydrogeologists. The Geoprobe alluvial research is conducted by MS and PhD students and overseen by faculty includes: a) Areal extent of aquifer compartments, b) Specific conductance to understand salinity variability, and c) Aquifer dissolved carbon, isotopes and groundwater dating to define groundwater pathways. Finally there are the opportunities and challenges of being the Geoprobe owner and operator responsible for operations, repairs, maintenance, upgrading and transporting equipment to the field. The opportunities include availability and flexibility in scheduling field work. The challenges are skills needed to operate heavy equipment, balancing use between faculty and students, safety risks, and mechanical skills to maintain and repair the Geoprobe.

Augmented Reality/Mixed Reality Platforms for Remediation

John Horst, PE, Nick Welty, PG and Allison Yanites

Communicating Groundwater Science

William Alley, Ph.D. and Rosemarie Alley

Drunkbusters

Jim Wright

Early/New Career Groundwater Professionals Panel: Take My Job, Please!

W. Richard Laton, Ph.D., PG, Steve Sliver, Rick Hutchings, Edd Schofield and Nicklaus Welty

Emerging Contaminants

How the PFAS regulations got to where they are and what you can legally do to recover costs for damages

Richard Head, JD
The path to the EPA PFAS (MCL) health advisory has been lengthy. Examining how regulations evolve provides insight on how to recover the cost from the polluters that caused the contamination. The seemingly haphazard journey to the PFAs health advisory from the Toxic Substances Control Act (TSCA) and Unregulated Contaminant Monitoring (UCMR) of drinking water, combined with improved analytical methods, has made it easier to identify and seek damages from the polluters.

Water utilities are facing substantial expense to deal with PFAS/PFOS contamination. They are struggling to understand how the EPA’s new health advisory will impact them and where funds will come from to pay for the costs of response and treatment.

This presentation will detail the legal review process that can be undertaken by a utility interested in pursuing cost recovery options for emerging contaminants including replacement or treatment of affected well, capital costs, and operation and maintenance costs for the lifetime of affected wells. The factors to consider when evaluating manufacturer liability will be reviewed. General resource commitments and timelines for undertaking this process will also be particularized.

Interstate Technology and Regulatory Council (ITRC) PFAS Team: Status of Achievements and Activities

Bill DiGuiseppi, PG
The Interstate Technology and Regulatory Council (ITRC) is a program of the Environmental Research Institute of the States (ERIS) and managed by the Environmental Council of the States (ECOS), the national, nonprofit, nonpartisan association representing the state and territorial environmental commissioners. The ITRC was established in 1993 as a public-private coalition working to reduce barriers to the use of innovative air, water, waste, and remediation environmental technologies and processes. ITRC produces documents and training that broaden and deepen technical knowledge and expedite quality regulatory decision making while protecting human health and the environment. ITRC achieves its mission through its Teams, which are composed of environmental professionals, including state and federal environmental regulators, federal agency representatives, industry experts, community stakeholders, and academia. ITRC Teams develop guidance documents and training courses. These products help state environmental agencies and others gain valuable technical knowledge and develop consistent regulatory approaches for reviewing specific technologies. ITRC Teams are led by state environmental agency staff.

In 2017, the ITRC formed the Per- and Polyfluoroalkyl Substances (PFAS) Team to address this large and expanding environmental problem in the US. The ~350 member team, made up of 41 states, 5 Federal agencies, and nearly 200 Tribal and public stakeholders, industry, and academic members, is by far the largest team of experts and interested parties ever assembled by the ITRC. The mandate for the team was to compile existing PFAS knowledge into a series of Fact Sheets, a Technical Guidance Document, and conduct Short Courses and Internet-Based Training (IBT) to educate and inform state and federal agency and environmental industry staff regarding technical issues related to AFFF and PFAS.

In the fall of 2017, ITRC published the first three Fact Sheets on “Naming Conventions and Physical and Chemical Properties”, “Regulations, Guidance, and Advisories”, and “History and Use”, followed by three more, on “Environmental Fate and Transport”, “Site Characterization Considerations, Sampling Precautions, and Laboratory Analytical Methods” and “Remediation Technologies and Methods” in the spring of 2018. The seventh and final Fact Sheet, on “Aqueous Film Forming Foam (AFFF)”, will be issued in the fall of 2018. Training was initiated in 2018 with a Short Course on “Managing PFAS Contamination at Your Site: Site Characterization, Sampling, Fate and Transport, along with Remedial Alternatives” at the Battelle Remediation Conference in Palm Springs, CA. Arrangements are being made for collaboration with other interested groups such as the Society of American Military Engineers (SAME), and planning is underway for 8-9 regional short course

trainings in 2018-2019, often in association with conferences or other industry events, as well as Internet-Based Training to be conducted in 2019. The full technical guidance document is being written by the team and will be published as a web-based document in 2019.

Geophysics for Groundwater Model Development and Monitoring

Airborne Geophysical Data for Building a Groundwater Sustainability Plan

Bill Brown
Airborne electromagnetic surveys (AEM) are capable of delivering high-quality subsurface data for building comprehensive hydrogeologic frameworks and the application of this method to map groundwater resources globally has increased in recent years. Water-resource managers have traditionally used borehole logs, surface geophysics and wells to gain an understanding of groundwater and its flow paths. This point source data may be scarce or difficult to obtain and requires interpolation between each data source that can introduce uncertainty in the resulting constructed model. Consider as well that a 6 inch borehole represents less than 1/millionth of one acre.

Advanced processing of airborne geophysical data with inversion and interpretation techniques can provide water resource managers with confidence in the results that can then be used to develop Groundwater Sustainability Plans. The geophysical data collected does not replace, but complements existing borehole data, thereby reinforcing the geological interpretation, which in turn leads to greater certainty of identified economical and productive drill targets. Once an area has been mapped with AEM the data can be interpreted for other targets as well, including location and extent of salt water encroachment, groundwater recharge areas, surface and groundwater connections, contaminant plumes and inputs for geotechnical and environmental engineering studies.

The paper will present data from AEM surveys carried out in California, Nebraska and Canada.

Geophysical CSAMT Survey Results and Groundwater Modeling in a Groundwater Appropriation Trial

Norman Carlson, PG
The role of geophysics in groundwater model development becomes particularly important when much of the model domain has alluvial cover, and the presence or absence of important faults that may influence groundwater flow is unknown. We discuss a good recent example at the Campbell Ranch project in New Mexico, in which much of the study area is covered by unconsolidated Quaternary units, but in surrounding areas where bedrock is exposed, the area is complicated with numerous faults and folds, with complex geologic structure. As a result, subsurface structure that may be significant in the groundwater modeling was suspected, but unknown. Since multiple aquifers were present and the depth of interest was moderately deep (> 3,000 ft), a CSAMT (controlled source audio-frequency magnetotellurics) electromagnetic survey was performed along six survey lines in an effort to better understand the subsurface. The CSAMT survey identified multiple buried faults, several of which proved important in calibration of the groundwater modeling that was used to calculate future impacts on existing wells from proposed new wells.The CSAMT results were presented during a groundwater appropriation trial in New Mexico.

Geophysical Surveys to Maximize Horizontal Well Yield and Extend Production in Depleting Aquifers

John Jansen, Ph.D., PG
Directionally drilled horizontal wells are an effective way to increase well yield from thin aquifers and extend production in aquifers with declining saturated thickness. The capacity of a horizontal well is a function of the permeability of the formation and submergence of the screen. Selecting a viable horizontal well site requires that the properties of the aquifer be understood along a long linear path. This can be a difficult task in patchy aquifers or aquifers that lie in narrow channels. Geophysical methods offer an economic means to map aquifer properties of large areas to direct test drilling programs and find favorable horizontal well sites efficiently.

One such thin and patchy aquifer is the Ogallala Aquifer in the Texas Panhandle. The Ogallala formation was deposited as an extensive braided stream system that drained the eastern slope of the Rocky Mountains. The thickness of the sand and gravel deposits is highly variable with the thickest deposits filling stream valleys eroded into the underlying land surface. The thickness varies from about 0 to over 500 feet in a few buried channels.

The aquifer has been extensively pumped for decades and significant dewatering has occurred. In portions of the aquifer the saturated thickness is becoming a limiting factor controlling the production of a well and the sustainability of the supply. While the mining is not sustainable, wells in deeper portions of the aquifer with coarser sands will provide higher yields for longer periods. Thinner parts of the aquifer become dewatered but the deeper parts of the aquifer still contain saturated permeable material. While it is not possible to predict the thickness of the Ogallala based on surface topography, there are geophysical methods that can be used to map the thickness of permeable sand and gravel units above the underlying units.

A high resolution electrical resistivity survey conducted in west Texas for an industrial client. The client had an extensive well field to provide cooling water for an industrial facility but regional declines in water levels continues to reduce the capacity of most of the wells. Seven miles of resistivity lines were used to map the deeper portions of the aquifer. Subsequent test borings confirmed the channels, which varied from about 100 to about 200 feet deep, with the coarsest formation in the deepest part of the channels. A horizontal well was constructed in one of the deeper channels with a capacity of about 900 gpm. The additional submergence provided by siting the well in a deeper channel with coarser sand and gravel significantly increased the capacity of the well and extend the usable life of the aquifer in the face of declining water levels. The net effect is to more efficiently mine a depleting aquifer which raises long term sustainability and management issues. This is at best a short term solution but it can keep critical infrastructure in service for several years to a few decades until sustainable solutions can be developed.

Hydro-TISAR – A New High Resolution Seismic Imagery Method for Hydrogeological Investigations

Milan Situm
Hydro-TISAR – A New High Resolution Seismic Imagery Method for Hydrogeological Investigations

Several complementary geophysical tools have been used to characterize the physical properties of the overburden and/or rock for relatively shallow hydrogeological investigations of less than 50 meters. They include classic geophysical methods such as Electromagnetics (EM), Very Low Frequency EM (VLF), Time Domain EM (TDEM), Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT). Seismic methods have been underutilized despite the fact that refraction and Multi-channel Analysis of Surface Waves (MASW) provide hard numbers for depth as well as soil and rock strength. Great efforts have been made to improve the resolution of P or S wave reflection, but little to nothing could be achieved in the critical upper 30 meters where over 95% of groundwater problems and engineering interest resides. Thus, an alternative method is proposed using frequency domain analysis, Hydro-TISAR. Thin groups of a few millimeter joints in rock can be detected as well as narrow gravel lens within sedimentary materials. Consequently, water bearing geological structures can be resolved. The seismic method is very field flexible in terms of survey design and simple seismic sources and a typical engineering seismograph. The presentation is in the form of a 2D sections, but also pseudo-3D and real 3D seismic imagery can also be produced. Moreover, the same seismic records can be re-processed as MASW records over targets of interest (in the case of overburden), to improve the identity of the geologic features. Conversely, 2D MASW data set can be process as Hydro-TISAR. Separate Hydro-TISAR case histories related to overburden and rock as they relate to groundwater exploration and contaminant flow path detection are presented.

Green Infrastructure

Daniel O'Rourke, PG

Groundwater Data Available to the Public -- USGS and the National Groundwater Monitoring Network

Rodney Sheets, William L. Cunningham, Charles W. Schalk, Candice Hopkins and Daryll Pope

Groundwater Industry Legislative Update and Current Issues

Lauren Schapker and Margaret Martens

Groundwater Modeling

Application of 3D Visualization Modeling to Improve Conceptual Site Model Development and Groundwater Remediation

Richard Boone, CPG, CHMM
Three-dimensional (3D) visualization modeling can be extremely useful to analyze and present data for environmental assessments, remedial planning, and litigation support, as well as regulatory and public relations. Two-dimensional (2D) contours and 3D volumes of stratigraphic and chemical data are interpolated with statistical models, which include variography and kriging algorithms. A 3D geologic and chemical model was developed for a multi-layer unconsolidated aquifer system impacted with chlorinated volatile organic compounds (CVOCs). The 3D model served as a comprehensive tool to (1) enhance communication and provide a better understanding of subsurface environmental conditions, (2) formulate and refine the conceptual site model (CSM), and (3) focus future resources on data collection for design of a hydraulic control interim remedial measure (IRM). Application of the 3D visualization model resulted in an improved interpretation of cross-unit vertical communication areas, confirmation of comingling with an offsite CVOC plume, and a refined approach to focused remediation of the core of onsite CVOC plumes, which resulted in cost savings. A four-dimensional video animation of the 3D visualization facilitated the evaluation of the vertical communication between aquifers and the distribution of CVOC mass, which is both dissolved within the aquifer and stored in the confining units between the aquifers. Geospatial data files of the updated hydrostratigraphic units were directly imported into a 3D numerical groundwater flow model to develop the design of the pump-and-treat IRM. The use of the 3D visualization, video animation, and interaction with the groundwater flow model enhanced site characterization and communication with the client, USEPA, and other stakeholders.

Development of a Revised Hydrogeologic Conceptual Model of the Indian Wells Valley Groundwater Basin

Max Halkjaer
The Indian Wells Valley groundwater basin occupies approximately 600 square miles of high desert and is bounded by the southeast terminus of the Sierra Nevada Mountain range on the west, the Coso Range on the north, the Argus range on the east, and the El Paso mountains on the south. The surrounding watershed encompasses roughly 860 square miles of mountains, hills, and valley floor, occupying the northwestern-most portion of the Mojave Desert, along the western edge of the Basin and Range geologic province.

The geology and structure of the Basin has been well-studied using geophysics, gravity and magnetics, deep boreholes and monitoring wells. Indian Wells Valley is a structural half-graben produced by faulting, primarily along the Sierra Nevada frontal fault and Argus frontal fault, with the basement generally tilted downward to the west. The basin structure is further defined by the Garlock left lateral strike slip fault that bounds the basin along part of it southern boundary. Additional major mapped faults in the basin include the Little Lake and Airport. There are numerous smaller faults making the basin geology and structure complex. The deepest area of the valley (based on drilling data) is in the west-central area with basement encountered at approximately 6,500 feet below land surface.

The basement and highlands of the basin are of late-Cretaceous igneous and metamorphic rocks. Surficial geology in the basin generally consists of alluvium, lacustrine and playa deposits, sand dunes, and consolidated rock. The lower-most alluvial materials are of early Tertiary age, consisting of compact, consolidated alluvium derived from the basement rocks, which include some lacustrine beds containing pyroclastic materials and minor volcanics. Lacustrine and playa lake deposits as much as 800 feet thick underlain by alluvium dominate the north central portion of the basin, and alluvium dominates the western portion of the basin.

Two principal aquifer units have been identified as the shallow and deep (or main regional) aquifers. The shallow aquifer extends from land surface through the sand dune deposits, younger lacustrine and playa deposits, and shallow alluvium to approximately 400 to 500 feet below ground surface. Water quality is generally poor in the shallow aquifer with total dissolved solids (TDS) greater than 1,000 mg/L. The base of the shallow aquifer is not well defined, but has been estimated from 1,950 ft above mean sea level (msl) at its western edge to 1,850 ft above msl near China Lake.

The shallow and deep aquifer are separated by an intermediate hydrogeologic unit consisting mainly of low permeability lacustrine and playa clays, but containing sand stringers that create transmissive water bearing zones that can be highly productive. The unit acts as a confining bed to deeper, productive water bearing zones, but also can be screened by wells and considered part of the deeper aquifer.

The deep aquifer is semiconfined to confined in the eastern portion of the basin by silt and clay from the overlying lacustrine and playa deposits, but otherwise mostly unconfined. The medium-to-coarse grained alluvial and fluvial sands and gravels have an estimated saturated thickness of 1,000 ft and are the main source of water to the Basin producing adequate flow rates and TDS less than 1,000 mg/L.

Groundwater replenishment occurs dominantly from Sierra Nevada Mountain snowmelt and mountain block recharge. Additional smaller sources of recharge include inflows from the adjacent Rose Valley, Coso Valley and El Paso subbasins/subareas. Groundwater flows from the southwestern El Paso subarea to the northeast, the Rose Valley to the southeast, from the Sierra Nevada to the west, towards China Lake and to two pumping centers. Discharge primarily occurs through groundwater pumping and the China, Mirror and Satellite playa lakes located in the east-central portion of the Basin.

The basin is part of the Stanford Groundwater Architecture Project and was surveyed with aerial electromagnetics in late 2017, initially conducted to provide improved information on water quality and lithology to support a brackish groundwater resources feasibility study. An extensive effort to comprehensively assemble all pertinent hydrogeologic data began in late 2017, with all pertinent data stored in the GeoGIS data management system, which was completed in spring 2018. An updated hydrogeologic conceptual model is being developed with GeoGIS and GeoScene3D, to be completed in July 2018, and results will be presented along with the workflow and challenges to complete the project.

Methodology and Framework for Developing Groundwater FEFLOW Conceptual and Numerical Model to Couple with Mike 21 FM: Miami Beach Case Study

Carlos Tamayo
Sea level rise (SLR) is occurring in coastal environments and poses a major threat to communities and infrastructure. Cities along the eastern coast of the United States are currently being affected by SLR; thus, adaptation is crucial to assure resiliency. In Miami, FL, a large portion of densely urbanized areas within Miami-Dade County are experiencing major investments in infrastructure. Consequentially, the entire area is very vulnerable to effects of climate-change, such as SLR and hurricanes, among others.

Miami Beach, FL, is a quite interesting example to analyze considering that it experiences a lot of what was mentioned above. It is a densely urbanized coastal city that is exposed to extreme weather events, sea level rise, and its residents and infrastructure are in a very vulnerable position. Residential and commercial high rises, high end neighborhoods, and preserved historic buildings are the general makeup of the city. Moreover, highly permeable formations, shallow groundwater levels, rising sea levels, and tidal effects, create a perfect setting for saltwater intrusion (SI) to occur and worsen through the years.

As part of a larger study, a groundwater model is being developed for coupling with a surface water model with the purpose of assessing interactions between them. The City of Miami Beach (City) is the testbed for this study and the broader goal is to evaluate soft and hard engineering solutions for adapting to SLR. A comprehensive assessment and modeling of dike-subsurface barrier systems (DSBS) for adaptation in coastal areas, at various scales worldwide, as a function of coastal prevailing geology is carried out. The coastal geology of South Florida, where a highly porous limestone aquifer exists (i.e., Biscayne Aquifer), is one of the various settings to be considered.

For this portion of the study, the main goal is to delineate the methodology and framework to develop the groundwater conceptual model, generation of numerical model, data input process, boundary conditions applications, running, and results analysis processes. The numerical model is FEFLOW and this methodology follows the specific requirements for the model to be adequately suited for the coupling interface with the surface water numerical model, Mike 21FM.

Study of Scale and Time Dependent Parameters for Reactive Solute Transport through Stratified Porous Media

Abhimanyu Sharma
In this study, better simulation of observed experimental data for reactive solute transport through stratified porous media is intended. Effectiveness of distance and time dependent dispersion (TDD) to simulate fate of sorbing solute is compared to fulfill this objective. A physical and chemical-non-equilibrium (MPNE) model is used to capture this phenomenon to account for heterogeneity and site specific sorption in subsurface soil medium. Nonlinear least square optimization algorithm is used to estimate transport parameters. For a better resolution during breakthrough and tailing portion, semi-log plots are used to characterize the time scale simulation. Experiment data of reactive solute (fluoride) transport reported in Swami et al. (2016) is used for comparative analysis. It is observed that MPNE with TDD simulate experimental results with higher accuracy compared to distance dependent dispersion, especially in breakthrough and tailing portions. Parameters estimation algorithm resulted lesser values of effective dispersion and first order diffusive mass transfer for TDD. While higher values of effective dispersion and mass transfer coefficient for distance dependent dispersion identifies an overestimation in solute spreading for identical transport processes. To have a better idea of distance and time dependent dispersion in terms of mass recovery, temporal moment is calculated. Zeroth temporal moment obtained in the case of time dependent dispersion is less, which suggests that effective dispersion is less for TDD. Peclet and Damkohler number are computed to identify the dominance of dispersion and mass transfer over advection since porous medium is affected by physical heterogeneity. It is concluded that TDD gives a better description of contaminant transport through heterogeneous porous media, since it takes in to consideration the temporal variability of dispersion and diffusive mass transfer during the complete evolution of solute.

The MODFLOW 6 Modular Hydrologic Model

Christian D. Langevin, Ph.D.
MODFLOW 6 is the latest core release of the U.S. Geological Survey’s modular hydrologic model. MODFLOW 6 synthesizes many of the recent MODFLOW advances into a single program and provides an object-oriented framework for adding new types of models and packages. The first release of MODFLOW 6 contains the Groundwater Flow (GWF) Model, which combines most of the capabilities of MODFLOW-2005, MODFLOW-NWT, MODFLOW-USG, and MODFLOW-LGR. The GWF Model supports both structured and unstructured grids, with the capability to remove thin or inactive cells from the simulation. When thin cells are removed from the simulation, the model automatically connects overlying and underlying cells. The GWF Model includes a new formulation, called XT3D, for representing full, three-dimensional anisotropic groundwater flow and for improving the flow approximation for certain grid types. The GWF Model in MODFLOW 6 contains the six, traditional MODFLOW stress packages (Well, Drain, River, General-Head Boundary, Recharge, and Evapotranspiration) and four advanced hydrologic stress packages (Multi-Aquifer Well, Streamflow Routing, Lake, and Unsaturated Zone Flow). MODFLOW 6 also includes a new and generalized way to move water between these hydrologic stress packages. This new capability can be used to route water from drains into a stream, for example, or to send rejected infiltration into a nearby lake. The object-oriented framework also makes it possible to tightly couple any number of parent, child, and grandchild models, or to couple an unstructured GWF Model of a shallow aquifer with a deep aquifer GWF Model that uses a regular grid. Future plans for MODFLOW 6 include the addition of a new subsidence package, variable-density groundwater flow, and transport.

Using Periodic Pumping to Characterize Aquifers: Field and Modeling Advantages

Michael Cardiff, Ph.D.
Pumping tests and slug tests are commonly implemented as reliable methods for estimating field-scale aquifer parameters (transmissivity or hydraulic conductivity), and when resources are available for multiple such tests, they provide a method for interrogating aquifer heterogeneity. A less-commonly used strategy is the implementation of periodic pumping tests, in which the head or flow rate in a well is oscillated at a set period. In this presentation, we discuss 3 aspects of oscillatory tests relevant to field practitioners: 1) Reliable and low-cost methods for implementing periodic pumping tests in the field; 2) Strategies and guidelines for the analysis of obtained pressure data, which consists of sinusoidal pressure changes with obtained amplitude and phases; and 3) Methods for recognizing and interpreting the effects of aquifer heterogeneity on oscillatory pumping tests, which can be especially apparent during multi-frequency testing. Results of robust analyses will be demonstrated from field applications in noisy, non-ideal environments.

Groundwater Monitoring

Benefits and Limitations of Using Down Well, Real-time, Telemetric Water Quality Meters to Monitor Water Quality

Brian Symons, PE
Background

While recent developments in real-time, telemetric water quality meters provides benefits over older equipment and grab sampling using manual methods, an understanding of both the benefits and limitations of new technology is required for successful application.

With respect to benefits, current technology allows operation of real-time sensors in the field for several months without calibration or maintenance, reducing labor requirements at remote sensing sites. A multiparameter probe allows collection of a multitude of important parameters using a single integrated system, and can incorporate state-of-the art sensing methods for each parameter in a unit small enough to insert in a 2-inch groundwater monitoring well. The addition of telemetry and web-based data management allows real-time review and evaluation of field data from multiple locations, near or far.

Review of technical literature, discussions with technical experts, and personal experience operating equipment under various field conditions, also allowed definition and verification of equipment limitations related to installation, accuracy, telemetry, and data management.

Objectives

This presentation will compare the benefits and limitations of example equipment (In-Situ Inc. Aqua TROLL 600 and Tube 300R) at four sites in four different states and their water quality conditions.

Benefits

  1. Provides a continuous, real-time record of groundwater conditions using accurate water quality parameters.
  2. Detect short-term events (i.e. minutes to several days) that can be missed during monthly or quarterly manual sampling events.
  3. Monitor water level, temperature, total dissolved solids, oxygen-reduction potential, dissolved oxygen, turbidity, pH, nitrate, ammonia, and chloride, downhole.

Limitations

  1. Location and/or configuration of the monitoring point may limit the Tube 300R telemetry system’s ability to transmit real-time data.
  2. The total set of parameters is limited.
  3. Because the equipment is connected and suspended by cables, site-specific cable lengths and suspension devices are needed.

Cloud-Based Analytics Dashboard Advances Real-Time Data Analysis While Supporting Collaboration and Active Groundwater Management

Charles Dunning, Ph.D.
Cloud-based groundwater monitoring enables real-time data analytics that support active and
sustainable resource management. New telemetry systems that leverage local internet connections
make it possible for data to be cost effectively delivered to cloud databases and online dashboards in
real-time. Leveraging the computing power available in the cloud, real-time, online dashboards provide the opportunity to create and update analytical modules that include groundwater hydrographs, tables and maps, but they also allow for customized, network-scale metrics, comparisons and statistics designed to streamline the workflow from data collection to active management by simplifying and automating data processing and analysis. Monitoring network sponsors, data users, and well owners can choose to display the modules that support their specific groundwater-level data or management needs, or they can collaborate with the dashboard system administrators to develop new modules based on metrics, statistics and comparisons they find useful. Through these collaborations, the collection of modules and metrics available to all users of real-time dashboards can grow, encouraging discovery of new ways to analyze, interpret and understand groundwater data. Real-time analytics dashboards are not only improving data integration into the strategic groundwater management process, they are now creating a forum for new and innovative ways to interpret groundwater data leading to new insights across the groundwater monitoring and management fields.

Developing a Threat Assessment and Monitoring Framework for Urban Karst Groundwater Management

Rachel Kaiser
In urban karst areas, such as the City of Bowling Green, Kentucky (CoBG) and the Tampa Bay Metropolitan Area (TBMA), groundwater quality faces a variety of threats. The development of residential, commercial, and industrial landuse types allows for a wide variety of groundwater pollutants to enter the karst groundwater systems. Various different models and indices, including the Karst Disturbance Index (KDI), Karst Aquifer Vulnerability Index (KAVI), and the Karst Sustainability Index (KSI), have attempted evaluative approaches to identify issues in urban karst areas, but the methods vary by location and lack a focus on urban karst groundwater quality, as well as a lack of a data-driven approach that is able to capture short- and long-term changes in threats to groundwater quality as a result of urbanization. The overall purpose of this study was to develop a holistic, data-driven threat assessment and monitoring framework for urban karst groundwater systems to better determine the possible threats, data collection needs, monitoring parameters, and analytical approaches needed to ensure groundwater quality is maintained in urban karst regions. This study focused on: 1) determining what indicators, parameters, and data quality need to be prioritized to create an effective, holistic monitoring framework for urban karst groundwater, and 2) developing an effective threat assessment and evaluative framework for urban karst groundwater quality sites using historic and modern data in an urban karst setting. The outcomes include an index and evaluation tool review, historical data evaluation and review, a threat and monitoring evaluation system for the urban karst landscapes using GIS and a Karst Feature Inventory (KFI), and primary data collection in the City of Bowling Green on water quality parameters. The final results of this study will be used to create a data-driven urban karst groundwater threat assessment and monitoring framework that can be used universally.

Ion Tracer to Quantify Drill Fluid Impact During Vertical Aquifer Profiling

Ramsey Ferguson, PG
Abstract:

A case study is presented where an ion tracer was added to drilling fluid to assess the impact of drilling fluid on groundwater samples during vertical aquifer profiling (VAP). VAP involves collecting and analyzing discrete groundwater samples at a mobile on-site laboratory, providing near-real time data for guiding site characterization. At sites where drilling fluids are required, a method is needed to evaluate whether water introduced during advancement of the boring impacts the quality of (or dilutes) the discrete groundwater samples. This presentation will cover the design and implementation of the tracer method along with lessons learned to effectively implement this approach for future work. It will cover the background information of the specific project, including drilling equipment used, sampling equipment, mobile laboratory requirements, aquifer type, and specific problems encountered to better assist others in implementation of this method.

Use of the tracer in the drilling fluid allowed for determining whether discrete groundwater samples were representative of field conditions or diluted by the drilling fluid during VAP. By introducing the tracer at a known concentration into the drilling fluid, then screening the groundwater samples in a field laboratory prior to analysis for contaminants, we were able to estimate the percentage of the sample that was comprised of drilling fluid. With a threshold of ten percent or less, we could confidently analyze the samples for target contaminants knowing that they were not compromised by the introduction of drilling fluid. The detection of tracer compound was also used as a criteria during development of monitoring wells placed in the same boring.

Monitoring of Pollutant Movement Along a Line of Transect within the Freshwater Field of Umm Al-Aish, Kuwait

Amitabha Mukhopadhyay
A large number of oil wells were damaged and put on fire in various oil fields of Kuwait during the 1991 Gulf War. The fresh groundwater resources of the Raudhatain and the Umm Al-Aish water fields in Kuwait have been affected by hydrocarbon compounds (HCs) derived from the oil released from these damaged wells and by salts derived from seawater that was used to extinguish the oil fire. Water quality data collected from a series of monitoring wells completed at different depths and arranged along a line of transect have been presented and evaluated to understand the spread of these pollutants in the vicinity of the Umm Al-Aish water field.

From an analysis of the data, it has been suggested that the salts derived from seawater and HCs moved together. The concentrations of the total dissolved solids (TDS) and HCs in the groundwater samples along the line of transect have, in general, increased over time though local variations in this trend have been observed. The concentrations of the pollutants, however, show a decreasing trend as one moves away from the oil lake along the line of transect. A reducing condition prevails in the locations where hydrocarbon pollution is significant. The periodic addition of the contaminants by the infiltration of run-off during the rainy season and mostly recalcitrant nature of the hydrocarbon contaminants are the possible reasons for the lack of overall attenuation of the pollution.

The presence of a source of pollutants (e.g., a non-aqueous phase petroleum liquid/NAPL) within the aquifer in the neighborhood of the wells P33U/P-33UA/P-33UB has been suggested on the basis of the depth distribution of pollutants at this site. The decrease in pollutant concentration with distance from these wells and the oil lake is, in all probability, due to dilution through mixing with uncontaminated water.

Monitoring Optimization: Lean Approaches and Lessons

Jay Piper, CEM
The USEPA has promoted Lean and Six Sigma approaches for a decade. Lean concepts and approaches provide a framework for monitoring program optimization, quality, and cost saving initiatives at complex sites. A set of groundwater and surface water monitoring programs evolved and improved over seven years during site characterization supporting RCRA Facility Investigation (RFI), interim measure (IM) monitoring, and monitoring during remedy design. The Lean concept of 8 Wastes (defects, overproduction, waiting, non-utilized talent, transportation, inventory, motion and extra-processing) helped focus on areas for improvement. Examples of initiatives that reduced these “wastes” will be presented. Lean tools were used to support root cause analyses, and to select improvement projects. Ten percent or greater annual cost savings were achieved while defects reduced to zero.

Improvement projects included modifications to reduce sampling frequencies and depth intervals, and trials that led to approval of low flow methods for groundwater sampling and automated water level data collection. Constraints were removed by justifying analytical methods with longer holding times, and more ergonomic or efficient field methods. Visual management approaches such as one-page snapshots were used to support consolidation and reduced frequency of extensive bound reports. The cost of non-compliance was avoided by modifying schedules and access procedures to protect cultural and biological resources. Mobilization costs and the environmental footprint of monitoring were reduced by cross training IM operations staff to support all monitoring activities, a measure that also increased responsiveness to short term data collection needs.

Lean tools such as the Pareto diagram help select improvement projects aligned with cost/benefit considerations, and explain why some initiatives succeed, and other initiatives don’t fully achieve intended results. Lessons and suggestions will be shared for approaches in monitoring programs to identify improvement projects that reduce defects, lower cost, and increase performance against any site metrics.

Stable and Radio Isotope Analysis Identified Sources of Methane During an In-Situ Remedial Action

Richard Coffin
Methane can originate thermogenically from regions of petroleum formation within the earth and/or via microbial fermentation of fermentable carbon and subsequent microbial reduction of carbon dioxide. Hence, the origin of methane is not always clear. Such was the situation where Provect-IR® antimethanogenic ISCR reagent was applied to treat chlorinated solvents in groundwater at a former dry cleaner facility. The technology rapidly and effectively reduced the concentration of PCE in groundwater thus meeting the project goals without the accumulation of catabolites (TCE, DCE or VC) and without excessive methanogenesis (e.g., <2 mg/L) in the treated area. However, about 9 months post-treatment, methane (5 to <10 mg/L) was observed downgradient of the treated areas. The source of the methane was potentially a result of the remedial action. Alternatively, the methane was not a direct result of the remedial action, noting: i) the area of interest was directly associated with gasoline/Diesel USTs (removed but no active remediation was performed), ii) the soil gas contained CH4 along with BTEX and other gasoline COIs, and iii) there was <500 ppm TOC in groundwater emanating from the upgradient treatment area (unlikely to produce that much CH4). In addition, there were sewer lines, utilities, multiple gasoline stations, and operation industrial activities in the immediate area.

Carbon isotope analyses - radiocarbon (Delta14C) and stable carbon (del13C) – where coupled with methane (CH4) and carbon dioxide (CO2) data from groundwater samples to determine the origin of the respired carbon. The del13C range for carbon sources respired in the process would be approximately -26.5‰ and 33.0‰ for Provect-IR and TPH residuals, respectively. Delta14C is approximately 0‰ and -999‰ for Provect-IR (young carbon) and TPH (old carbon), respectively. The data confirmed that the methane originated primarily from sewer gasses with some contribution from the remedial amendment proximal to its application area.

Tagging and Tracking Pumping Influence Provides Critical New Insight Across Monitoring Networks

Joseph Fillingham, Ph.D.
Removing the influence of pumping from groundwater-level data sets, manually or algorithmically, is cumbersome, error prone, and limits network data density. Conversely, water use and pumping from production wells may be a previously undocumented, but critical influence on real groundwater-level change across a network. A new method for tracking and tagging the influence of pumping on groundwater-level measurements supports accurate and more efficient interpretation of how pumping influences groundwater levels across a monitoring network. Using a simple current transducer to track pumping activity, a groundwater-level system is able to assign tags to capture the situation of the well and pump at the time of the reading. A “Timed” sensor reading tag reflects the absence of pumping, “Pump Influence” is a timed reading taken when the pump is running or within the recovery period. If pumping specific duty is necessary, or useful, tags can be applied to groundwater-level readings that reflect pumping drawdown and well recovery for each pumping event. With each groundwater-level reading tagged either Timed, Pump Influenced, Pump Start, Pump Stop, or Well Recovery, the identification of static and pumping influenced groundwater-levels becomes simple and error free. When tagged measurements from multiple wells are integrated across a monitoring network, the influence of multiple pumping wells on an aquifer can be isolated from the broader influences of weather, seasons, and climate, providing vital insight into background and man-made changes to the groundwater resource supporting fact-based sustainable management strategies.

The Effect of Close-Proximity Blasting on Groundwater Quality and Impacts on Communal Drinking Water Supply Systems

Andrew Bingeman
The Effect of Close-Proximity Blasting on Groundwater Quality and Impacts on Communal Drinking Water Supply Systems: A Case Study by Farouk Abu-Hijleh, Andrew Bingeman, Peter A. Gray, and Kassandra Wallace Abstract

This paper investigates the influence of close-proximity blasting for a utility corridor on groundwater quality within a dolostone bedrock aquifer and the effect on a hydraulically down-gradient communal drinking water supply system. Mobilization of fine-grained materials in the fractures of a bedrock aquifer system can be attributed to the agitation of the system due to blasting. A case study is presented on a drinking water supply system where blasting was occurring in close proximity to the supply well. Comparisons of the filter replacement frequencies were used to assess groundwater quality prior, during and post-blasting. A cause-and-effect relationship was identified between the close-proximity blasting and increased filter replacement frequency, demonstrating the effects that close-proximity blasting can have on groundwater quality and down-gradient drinking water supply systems.

Groundwater Remediation including Combined Remedies Part 1

Kevin Finneran, Ph.D.

Animal Co-Products as Novel Electron Donors for In Situ Bioremediation

Kevin Finneran, Ph.D.
Chlorinated solvents account for approximately three quarters of all bioremediation sites. The vast majority of these remediation applications are predicated on a simple strategy: amend a high molecular mass electron donor into the subsurface so Dehalococcoides-like microorganisms are stimulated, and the activity is promoted over the long term. Thus far all long-term electron donors have been derivatives of soybean oil, which is problematic because of: a) limitations in the microbial populations that actually utilize strictly lipid electron donors, and b) competition with foodstuffs in US production. We have developed electron donors from rendered animal co-products, which are combinations of lipid, protein, and minimal carbohydrate. Thus far 21 co-products have been tested, and all stimulate complete dechlorination to a rate and extent, which is better than any current soybean oil-based electron donor.

Incubations were constructed using TCE-contaminated aquifer material, and each electron donor (co-product) was added as the sole electron donor. Each animal co-product was compared to 5 controls containing common electron donors (lactate, acetate + hydrogen, and one soybean oil-based electron donor) and a sterile and unamended controls.

Lactate was the fastest of the 5 controls and as a result each animal co-product was compared to it. Of the 21 animal co-products, 17 completely dechlorinated the TCE to ethene at rates faster than lactate and 4 generated ethene at the exact same rate as lactate. In general, the more proteinaceous animal co-products were able to promote dechlorination at a faster rate than the animal coproducts with a higher fat content. All materials reduced TCE to ethene (at a 1:1 stoichiometry) faster than the commercially available soybean-based electron donor (e.g. emulsified vegetable oil). This strategy introduces a new electron donor for TCE bioremediation, which thus far is faster and more cost-effective than any electron donor reported to date.

Antimethanogenic Reagents (AMR) to Control Excessive Methanogenesis During Remedial Actions

Jim Mueller
Background/Objectives: At many groundwater remediation sites, excessive production of methane has been observed following the addition of conventional organic hydrogen donors such as (emulsified) oils/lecithin, sugars and conventional ISCR reagents. This is because methanogens are commonly the most ubiquitous indigenous microbes in anoxic aquifer settings. And given that methanogens replicate in 1 to 2 hours (whereas Dehalococcoides spp. for example double in 24 to 48 hours), they often bloom and dominate following the addition of organic hydrogen donors, thereby liberating large amounts of methane gas. There are multiple potential consequences of this response: i) decreased efficiency/performance, ii) increased costs, iii) reduced safety, and iv) lack of regulatory compliance. Hence, evaluating the need to actively control excessive methanogenesis during remedial actions is now commonplace among seasoned professionals as the positive effects on remedial performance, safety, regulatory compliance and sustainability become well understood.

Approach/Activities: Antimethanogenic reagents (AMRs) have been developed to specifically and proactively control Archaea growth during ERD and ISCR remedial actions. In various trials, the AMRs were effective at rapidly reducing ORP, stimulating reductive dechlorination reactions, maintaining pH, and reducing methane production as compared to their controls. The AMRs have been integrated into various remedial amendments (e.g., liquid ERD, solid ISCR, EZVI materials, sediment capping materials) and are currently the subject of independent laboratory and field studies evaluating performance, efficacy, longevity and impacts on environmental microbiology. Information on the reagents modes of action, dosing / application requirements, and lessons learned during their field implementation will be presented along with results of field performance monitoring and application costs.

Case Study – Challenges Encountered during Concurrent Implementation of Remedial Strategies at a Solvent Site

Joe Whearty
Groundwater, soil, and soil vapor below a former dry-cleaning facility are contaminated by tetrachloroethene (PCE) and various petroleum hydrocarbon compounds. Plumes of the various chemicals of concern are commingled onsite and have been delineated to extend below several city blocks. Fugro was retained by California Department of General Services to address risks posed, and to remediate the site for redevelopment. A Soil Vapor Extraction (SVE) system was the first remedy installed to mitigate vapor intrusion risk to nearby receptors. Thermal Desorption using Electrical Resistance Heating (ERH) was selected to remove contaminant mass in the Source Area. During ERH activities, Enhanced Reductive Dechlorination (ERD) in groundwater was implemented for the distal plume to promote the breakdown of PCE to its less harmful by-products. During operation of concurrent remedial technologies, several challenges required swift and dynamic changes in remedial system management. Notable challenges that arose include:
  • Chemical desorption of petroleum by-products required a change in the SVE monitoring program to address the increase in contaminant vapor stream waste loading.
  • Recovered steam contained more sediment than anticipated which complicated condensate treatment and disposal.
  • Heavy rainfall during the winter of 2016-2017 caused groundwater elevations to rise above a semi-confining layer, complicating vapor control and contributing to desorbed contaminant migration beyond the initial capture zone.

Positive effects have also been observed with the addition of ERH into the remedial strategy. These include:

  • Warmer groundwater temperatures induced by ERH have allowed dehalococcoides bacteria colonies to thrive.
  • Lateral spread of the inoculants injected during ERD near the Source Area appears to have extended beyond the application area.

Our collaborative working relationship with the ERH contractor allowed real-time solutions to challenges in treatment, waste capture, and monitoring methodologies, leading to a successful project.

Challenges of Iron in Groundwater Remediation Projects – A Case Study

Jason Downey, PE
Naturally occurring iron in the dissolved form is commonly found in groundwater across North America. This seemingly harmless compound can lead to a number of challenges for environmental engineers working to remediate properties with groundwater contamination where dissolved iron is present.

Iron in the dissolved form will readily convert to a rust colored precipitate called iron oxide when exposed to air in recovery wells, pneumatic pumps, vacuum extraction process lines, air strippers, and tanks. Iron oxide particles are typically in the range of 0.5 micron to 2 micron and can bind up to form larger particles. Once in the oxidized form, iron will settle and plug piping, tanks, reinjection wells, carbon filters, air strippers and bag filters, which result in ongoing operating and maintenance challenges and operating cost overruns.

The discharge of iron-impacted water is highly regulated in most regions. This is primarily due to the oxidation potential of dissolved iron, which consumes oxygen from rivers and streams, as well as the increased turbidity, and sedimentation of precipitated iron. The increasingly stringent regulations for iron-impacted water require remediation engineers to remove the iron prior to discharge in many applications.

newterra, working with a team of environmental consultants, experienced these challenges first hand on a brown-field redevelopment site in Belleville, Ontario. On this site, groundwater levels are monitored and controlled to prevent the flow of contaminated groundwater off the property.

newterra will present a case study on this project explaining the challenges found on this site, the process followed to qualify and quantify the iron problems, and the steps taken to narrow down the best treatment solution. In addition, the case study will describe the technology chosen to manage the iron problems on the project.

Combining Technologies and Implementation Methods to Address Chlorinated Solvent Impacts at Complex Sites

Mike Mazzarese
Complex sites require complex solutions. Challenges typically include heterogeneous geology and contaminant mass distribution, vadose and/or saturated contaminant mass, and concentrations that span several orders of magnitude. These require us as practitioners to often consider multiple remedial technologies and approaches to reach the site specific goals within the desired timeframes. Often technologies are inefficiently implemented sequentially; this extends the remediation timeframe and requires re-characterization between remedial phases. This presentation will highlight several projects where multiple technologies were successfully implemented in concert. Technologies to be discussed include abiotic chemical reduction, enhanced reductive dechlorination, and in situ chemical oxidation. Application methods to be covered include injection via direct push, injection via permanent wells, and in situ soil blending. The strategies for each site included different approaches for source (e.g. soil blending) and plume (e.g. permeable reactive barrier) remediation.

Site #1: In the source areas, Trichloroethene (TCE) concentrations in groundwater exceeded 50 mg/L. BOS 100®, a specialized catalyst manufactured by Remediation Products Inc., was used in the source areas. Enhanced reductive dechlorination was selected for treatment of the plume areas and involved injection of an electron donor and a dechlorinating culture.

Site #2: TCE concentrations have been detected in groundwater at a maximum concentration of 730 mg/L and in soils up to 6,800 ug/g. Soil blending was performed utilizing chemical oxidation (sodium permanganate) to treat the unsaturated TCE impacts exceeding an average 1,100 ug/g. BOS 100® was injected into the saturated zone in a barrier configuration to limit the mass flux from the source area and prevent contamination from leaving the subject property.

Groundwater Modeling and Monitoring Results for a Combined Thermal and In-Situ Bioremediation Remedy

Jason R. House, CG, PG
MODFLOW and MT3DMS models originally developed for contaminant fate and transport for the site and proximal portion of the downgradient plume area were converted into a heat transport model to evaluate the evolution of groundwater temperature over time and distance from the thermal treatment area. We present modeled temperatures and field data for downgradient temperatures associated with a source area thermal remedy, and the influence of the thermal front on a combined anaerobic bioremediation / chemical reduction remedy implemented in the proximal portion of the downgradient plume. The objective was to take advantage of the increased microbial activity and CVOC desorption to enhance bioremediation of the chlorinated plume immediately downgradient of the source area. Permeable reactive barrier zones comprised of a mixture of zero-valent iron and organic carbon substrate were installed to take advantage of the anticipated higher groundwater temperatures and provide abiotic degradation in the event of temperature excursions beyond those at which subsurface biological activity shuts down. The system was installed in December of 2017 and run for approximately 180 days. Adjustments to the thermal model to account for winter conditions and the use of a quench line to protect nearby utilities will be discussed. Groundwater temperature and chemistry data available from post shutdown monitoring will be discussed and presented to evaluate modeling efforts and system effectiveness.

Iron Enhanced In Situ Reductive Dechlorination in High Sulfate Aquifers

Daniel P. Leigh, PG, CHG
The geochemistry of groundwater reflects the rocks through which it has migrated. Notably, the groundwater in the Las Vegas basin (LVB) migrates through sulfate containing carbonate rocks such as gypsum (CaSO4·2H2O) and anhydrite (CaSO4). As the groundwater comes into equilibrium with these rocks sulfate can accumulate to concentrations up to several thousand milligrams per liter (mg/L).

The application of in situ biologically mediated reductive dechlorination for treatment of chlorinated volatile organic compounds (CVOCs) establishes sulfate reducing conditions in the groundwater. During this process bioavailable ferric iron is reduced to ferrous, and sulfate is reduced to sulfide. Very high sulfide concentrations are toxic to bacteria and can inhibit biological activity. At many sites, sulfide is removed from groundwater by combining with naturally occurring ferrous derived from the aquifer matrix. However, carbonate rocks, such as those in the LVB, may not contain sufficient bioavailable iron to sequester very high concentrations of sulfide, resulting in inhibitory conditions and incomplete dechlorination of the CVOCs. In such cases, groundwater can be amended with iron to remove sulfide from the groundwater, thereby allowing the complete biological reduction of the CVOCs.

The sequestration of sulfide by ferrous also forms highly reactive ferrous sulfide species such as mackinawite (FeS) and pyrite (FeS2). Upon contact with these iron sulfide species, CVOCs undergo reductive dechlorination by the β elimination pathway, bypassing the production of toxic daughter products. The combination of biotic and abiotic processes can reduce cleanup time. This biogeochemical degradation process has been applied at numerous sites to enhance biological reductive dechlorination.

This presentation will provide a description of the technology, general biological and geochemical degradation processes for chlorinated organics and the methods and results of the bench and field studies and will suggest methods for applying this technology for treatment of CVOCs in high sulfate aquifers.

Lessons Learned from Surfactant Enhanced Aquifer Remediation of Light and Dense NAPLs

David Alden, PE
Background/Objectives. Surfactants, solvents and polymers have been used as aggressive NAPL removal methods. Published work on thoroughly monitored projects shows that over 90% of the NAPL contaminant mass can be removed. How have more commercial remediation projects following these methods perform?

Approach/Activities. Technology developed at the University of Oklahoma, originally focused for enhanced oil recovery at petroleum reservoirs and subsequently adapted to the environmental arena, can lower the IFT sufficiently to allow physical mobilization of residual LNAPL with the limited production of thermodynamically stable emulsions. Part of this talk will focus on market acceptance and lessons learned from the use of artfully formulated surfactant blends that reduce solubilization and simply allow LNAPLs in saturated soils to become mobile. Lessons learned from other Department of Defense surfactant flood projects addressing DNAPL will be used to highlight similarities and differences to LNAPL recovery projects.

Results/Lessons learned. The presentation will review surfactant flood design methods and highlight results and lessons learned from various projects.

Optimization and Performance of ZVI Amendments for In-Situ Chemical and Biological Reduction

Gary Birk, PE
In Situ Chemical Reduction (ISCR) is an innovative environmental remediation technique used for soil and/or groundwater remediation that involves the placement of a reductant or reductant generating material in the subsurface to reduce the concentrations of targeted environmental contaminants to acceptable levels. Zero valent iron (ZVI) is most commonly used for remediating halogenated ethenes and ethanes, pesticides, energetic compounds and some metals/metalloids into harmless end products. [ITRC 2011]. The process combines both biological processes and ZVI particle-driven abiotic pathways to chemically reduce the contaminants. The incorporation of ZVI enhances remediation by enabling various chemical reduction pathways and for halogenated ethenes limits the formation of undesirable breakdown products such as Cis-DCE and vinyl chloride.

Recent studies were undertaken to evaluate the reactivity, surface passivation, and pH fluctuation of various commercially available ZVI powders and an engineered ZVI media with a greater surface area. The ZVI samples were under identical conditions for 103 days with a solid to liquid ratio was 1:20 by weight. Particle size of all ZVI was <100 mm. The lab-scale kinetic experiment demonstrated accelerated abiotic reactivity of the engineered ZVI media towards a mixture of c-VOC composing of tetrachloroethylene (PCE), trichloroethylene (TCE), cis-dichloroethylene (c-DCE), and 1,1,1-trichloroethane (111TCA) in synthetic groundwater (each compound at 5 mg/L).

The study concluded that the major difference between engineered ZVI media and off-the-shelf ZVI powders is the increased reactivity of the engineered ZVI media. The engineered ZVI media was also able to maintain circumneutral pH, generate higher rates of hydrogen and sustain the production of hydrogen for a longer duration.

Pilot Study Data Evaluation: Enhanced Attenuation of PFAS and VOCs in Groundwater

Jeffrey Holden, PE, LSP, LEP
The SRSNE facility operated between the 1950s and 1991 distilling and re-distributing spent industrial solvents. Releases resulted in the presence of non-aqueous phase liquids (NAPL) in overburden and bedrock. In the 1990s, two groundwater pump-and-treat systems were installed to capture the plume originating from the source area. The first (NTCRA 1) captured source area groundwater with a sheetpile wall and overburden recovery wells. The second (NTCRA 2) is downgradient of the sheetpile wall and uses overburden and bedrock extraction wells to hydraulically control the groundwater plume exceeding MCLs.

Between 2013 and 2015, thermal remediation of the overburden source zone removed ~500,000 pounds of VOCs and a RCRA cap was installed over the source area in 2016-2017. Expecting these measures would eliminate the need for long-term NTCRA 1 extraction, three valved penetrations were installed through the sheetpile wall, collection and redistribution trenches were constructed on the up- and downgradient sides of the wall, and fill was placed to account for predicted groundwater rise downgradient of the wall.

Despite orders of magnitude VOC concentration reductions in source zone soil and groundwater, and significant ongoing MNA, groundwater within the sheetpile wall remains more impacted than downgradient of the wall. PFOS and PFOA were also detected in NTCRA 1 groundwater at concentrations higher than in NTCRA 2 groundwater. Regulators expressed concern that allowing groundwater flow through the penetrations would degrade the downgradient water quality.

A pilot study was implemented to evaluate using zero-valent iron (ZVI) and PlumeStop® to treat groundwater within the trenches and minimize the potential for adverse downgradient water quality impacts. This presentation will provide an overview of the pilot study approach, summarize the monitoring performed to date, and preliminarily evaluate the materials’ effectiveness at attenuating PFAS migration in groundwater.

Removal of Chlorinated Solvents in Groundwater Using Immobilized Nano Zero-Valent Iron for Advanced Oxidation Processes

Erick Bandala
Advanced oxidation processes (AOPs) are powerful methods for water treatment, particularly to eliminate organic contaminants. Developing novel catalysts with enhanced hydroxyl radical generation properties leads to improved efficiency of AOPs. In this study, nanoscale zero-valent iron (nZVI) immobilized in biochar (SBA-15) was synthesized using the two-solvent method. Several different samples were synthesized with different iron to silicon (Fe/Si) ratios and using different synthetic conditions including pH, and ultrasonication. The immobilization of ZVI nanoparticles in the biochar particles was confirmed using material characterization tools. The composition analysis results of nZVI/biochar samples verified the efficient use of materials and suggested a correlation of the synthetic conditions and the performance of the catalysts. The synthesized materials were tested for hydroxyl radical (•OH) production. The results revealed high •OH production, particularly when 500 mg/L of the catalyst sample was used. Addition of peroxymonosulfate ion to the reaction mixture resulted in a significant increase in •OH production. The best reaction conditions were tested for the degradation of trichloroethylene and tetrachloroethylene as model chlorinated solvents. Different reaction conditions were tested to simulate water quality conditions potentially found in real groundwater such as pH and ionic strength. The novel material investigated here showed interesting characteristics as Fenton-like reaction catalyst, and worth being assessed for further environmental applications, such as soil treatment, site restoration, or the removal of contaminants from wastewater effluents.

Subgrade Biogeochemical Reactors: Design and Performance of Multiple Configurations

Jeff Fitzgibbons, PG
Subgrade biogeochemical reactors (SBGRs) are a unique green and sustainable remediation (GSR) technology for treatment of contaminant source areas and groundwater plume hot spots. SBGRs have been configured for multiple in situ treatment methods, including: enhanced reductive dechlorination (ERD), sulfate-enhanced degradation, and aerobic degradation. SBGRs have been used to effectively treat chlorinated volatile organic compounds (CVOCs) and/or fuel related contaminants in soil and groundwater, and treatment of other contaminants continues to be evaluated.

This technology is used to address persistent source area contamination at a lower cost and in a sustainable manner. SBGRs consist of the following common elements: 1) excavation of contaminated source area soils, 2) backfill of the excavation with gravel and SBGR amendments tailored to the contaminant(s) of concern, and 3) installation of a solar- or wind-powered pumping system to recirculate groundwater through the SBGR for treatment. Use of locally sourced farm and tree byproducts, reclaimed construction materials, along with off-grid groundwater pumping, creates a low-cost, low‑maintenance, and sustainable remediation solution.

SBGRs have been constructed in multiple configurations, including designs capable of meeting limited access restrictions at heavily industrialized sites or at sites with land surface disturbance restrictions due to sensitive species and wetland habitat issues. The SBGR treatment media has also been selected for multiple contaminants based on site-specific conditions. For ERD approaches at CVOC sites, SBGR treatment media have contained various types of organic mulch, new or recycled vegetable oil, iron pyrite, or magnetite sands. For fuel-related sites, SBGR treatment media have included recycled gypsum products for sulfate-enhanced degradation, or oxygen-enhancing amendments for aerobic degradation. This presentation will summarize the advantages and limitations of the SBGR technology. We will discuss performance results from several SBGRs, which are achieving 95-99% total molar reduction of contaminants and rapidly cleaning up contaminant source areas.

Groundwater Remediation including Combined Remedies Part 2

Kevin Finneran, Ph.D.

Best Practices for Environmental Site Management: A Practical Guide for Applying Environmental Sequence Stratigraphy to Improve Conceptual Side Models

Rick Cramer, PG
The purpose of this issue paper is to provide a practical guide on the application of the geologic principles of sequence stratigraphy and facies models to the characterization of stratigraphic heterogeneity at hazardous waste sites. Application of the principles and methods presented in this
issue paper will improve Conceptual Site Models (CSM) and provide a basis for understanding stratigraphic flux and associated contaminant transport. This is fundamental to designing monitoring programs as well as selecting and implementing remedies at contaminated groundwater sites. EPA recommends re-evaluating the CSM while completing the site characterization and whenever new data are collected. Updating the CSM can be a critical component of a 5 year review or a remedy optimization effort.

These methods are applicable to sites underlain by clastic sedimentary aquifers (e.g., intermixed gravels/sands/silts/clays). The scientific principles and methods presented in this document bring clarity to the challenges posed by lithologic heterogeneity thereby facilitating successful site management strategies. Lithologic heterogeneities can be characterized by the use of high resolution site characterization (HRSC) techniques (http://www.cluin.org/characterization/technologies/hrsc/). The application of sequence stratigraphy can be applied to new site investigations as well as existing site data to update the Conceptual Site Model (CSM). These methods allow the practitioner to place environmental subsurface data in a geologic and hydrogeologic context, and predict the geology where subsurface data are absent.

Water Treatment Technologies for PFAS: The Next Generation

Jeffrey McDonough
Of all the known persistent organic pollutants, few pose as complicated a challenge to the water treatment industry as poly and perfluoroalkyl substances (PFAS). This class of compounds does not readily biodegrade, they are highly mobile in groundwater aquifers, and early indications are that they will be regulated to extremely low levels (parts per trillion). In addition, many of the conventional water treatment strategies such as all forms of biological treatment, exploiting volatility for physical removal, and chemical oxidation are not applicable. For the time being, it is clear that PFAS-impacted water treatment will necessitate a treatment train approach that often involves a combination of sorption and separation techniques. The good news is that cutting edge advancements in treatment technologies are paving the way for greater treatment efficiency, even in the more challenging area of PFAS destruction. This presentation will preview exciting new treatment techniques and associated field applications that are on this cutting edge, like modified silica sorbents, a new method of separation via “ozofractionation”, and advancement of destruction-based technologies including sonolysis and electrochemical treatment. This next generation of technology opens up new possibilities for treatment effectiveness and efficiency that didn’t exist before and represent big areas of opportunity for further creativity! This will build off of the GWMR column of the same title published in Spring 2018.

Groundwater/Surface Water Interactions

A Comparison of Thermal Imaging and In-Situ Thermistor/Tensionmeter Data to Characterize Groundwater Seepage in a Fen

Ogochukwu Ozotta
Groundwater flow and its dissolved mineral transport plays a fundamental role in the ecology of many wetlands. Installation of thermistors and tensiometers to map groundwater seepage, however, is invasive and may damage vegetation and potentially affect biodiversity. By mapping surface temperature remotely in the late summer, when the differential between warm soil and cold groundwater is the greatest, we hypothesize that the temperature patterns will reveal areas of greatest upward gradient and flow.

To test the hypothesis, we monitored the effect that hydraulic gradient has on surface temperatures in a fen located at the north end of the Cherry Lake Aquifer, Eddy County, ND (47.73, -98.66). On-the-ground thermal imaging was used to map seepage, with results compared to conventional method of installing shallow ceramic cup tensiometers to measure hydraulic gradient, and estimate flux using Darcy’s law. Shallow temperature loggers (thermistors) were installed to characterize soil temperatures at the same sites. The approach was applied at contrasting two locations: a sedge-cattail covered (Sedge site) and a nearby shady willow- cordgrass covered (Willow site).

The Sedge site showed strong upward gradient whereas the Willow site showed variable gradients, perhaps related to greater transpiration. Temperature observations and trends determined from the thermal imagery and thermistors did not show a relationship to hydraulic gradients measured at either site, suggesting variability due to heterogeneity of hydraulic conductivity (K). Thus, application of thermal imaging to map groundwater discharge requires data on soil stratigraphy.

We used both forward and inverse modeling of temperature profiles, which is based on a one-dimensional solution to the advection-conduction equation (Kurylyk et al. 2017), to more thoroughly characterize the shallow variation of hydraulic conductivity. Coupled with additional field data on temperature distribution, gradient, and conductivity, we were able to map the fen seepage face.

The gradients are affected at some depth because of the varying soil stratigraphy. The groundwater is simply fanned out along the bed rather than mixing to the surface water, which defines the reason why the seepage faces cannot be mapped completely using thermal imaging. Conventional method could measure vertical flux of the location because it is calculated based on depth of the soil distribution than on the spatial playout.

Next Generation Sequencing for Management of Surface Water/Groundwater Interaction and Water Quality

Andrea Rocha, Ph.D.
Environmental microbial diagnostics is a rapidly evolving field that enables understanding of causal relationships between the microbial community and their environment that would be too challenging to otherwise investigate. This practice area has a wide range of applications, including the development of predictive models, cleanup and monitoring strategies, and bioremediation and biogeochemistry. Examples where environmental microbial diagnostics may be beneficial to meeting regulatory requirements with greater fidelity than currently practiced methods include EPA’s Surface Water Treatment Rule, Total Coliform Rule, and Groundwater Rule. Microbial diagnostic approaches also function as both leading and lagging indicators of environmental perturbations such as acidification of groundwater. One example of a microbial diagnostic tool is next-generation sequencing (NGS), which enables identification of microbial community signatures which can be used to identify environmental changes that may affect water quality, remediation performance, and other operational parameters influenced by the biological community. Although NGS is extensively used to study environmental communities, its use as a diagnostics tool to characterize the environment is in the early stages of development. In this presentation we present practical examples of where the use of NGS provided diagnostic information to understand factors that influenced the DNA signature of specific environments. Specifically, we used NGS to investigate potable groundwater for indicators of potential surface water intrusion. Results demonstrated the ability of NGS to supplement established technologies, such as micro-particulate analysis, for the identification of key surface water bio-indicators indicative of surface water intrusion. We will present another study where NGS was used as a diagnostic tool to define microbial signatures that are linked to known metabolic end-products that could contribute to the acidification of groundwater. Overall, NGS is a valuable technology that provides in-depth biological signatures of the ambient environment that can be used to inform and improve current water management and remedial strategies.

Surface Water/Groundwater Interaction: A Forensic Approach to Salinity in an Alluvial Aquifer

Erin Noonan
The Brazos River Alluvium aquifer is a minor aquifer in central and east Texas under water table conditions. It is an underutilized resource, and is being considered as a future supplemental water source. However, variability in salinity occurs throughout the Brazos River Alluvium aquifer and the source of this variability is unclear. The objective of this study is to characterize salinity variability in the northern segment of the Brazos River Alluvium aquifer and evaluate potential salinity sources. A common supposition is elevated salinity levels in the aquifer are the result of groundwater-surface water interactions between the aquifer and the Brazos River, which also exhibits a high salinity. However, other salinity sources include irrigation, evapotranspiration, and brine contamination from historic oil and gas activities. To characterize the variability of aquifer salinity, water samples collected throughout the study area were analyzed for ions, specific conductance, and stable isotopes of hydrogen and oxygen. The specific conductance of the northern segment of the Brazos River Alluvium aquifer ranges from 390 to 1,640 mS/cm and averages 916 mS/cm. The average specific conductance the Brazos River in the northern segment is 1108 mS/cm. The spatial distribution of specific conductance in the aquifer shows that specific conductance changes rapidly over short distances. In multiple instances specific conductance values double over the course of a few hundred meters. Specific conductance profiles show stratification in wells, and data loggers have been implemented to monitor changes in specific conductance over time. Preliminary data show that the aquifer and river appear to be ionically and isotopically distinct, and that groundwater-surface water interactions between the aquifer and Brazos River is not likely the major source of aquifer salinity. However, irrigation with water from the Brazos River could potentially indirectly affect the salinity of the aquifer.

Surface-water Reservoir Effects In A Shallow Karst Aquifer: Quantity, Quality Or Both

Joe C. Yelderman Jr., PhD, PG
The Anthropocene has resulted in numerous modifications to surface water/groundwater interactions. Understanding these changes is critical to effective and efficient water management. Surface-water reservoir construction in carbonate terrain may affect adjacent shallow karst groundwater systems by elevating local water levels and the resulting increased flow may cause safety concerns if dissolution accelerates. Causes for changes in the adjacent heterogeneous karst groundwater system are challenging to determine, and solutions to the associated problems lend themselves to local flow-system approaches rather than aquifer concepts. Stillhouse Hollow Reservoir in Central Texas is exemplary of many reservoirs designed for both water supply and flood control which results in large water level fluctuations. Increased spring flow in the nearby Edwards aquifer has been hypothesized as the response to reservoir water levels but this connection remains unconfirmed. Deployment of dataloggers and routine measurements of spring flow compared to reservoir levels and precipitation events have proved challenging and helpful, but not conclusive. Analyses of temperature, specific conductance, ionic chemistry, and stable isotopes in both the springs and the reservoir added information critical to understanding the karst heterogeneity and hydraulic connections.

The results indicate hydraulic connections are related to the karst heterogeneity in response to reservoir management and vary in location and magnitude. The conclusion is that there is a need for creative investigative approaches combined with a variety of analytical methods to understand hydrogeologic changes in the Anthropocene such as those observed in this portion of the Edwards aquifer affected by Stillhouse Hollow Reservoir.

Grouting Tools and Techniques for Geothermal Wells

Stewart Krause, Todd K. Tannehill and Jeff Blinn

Karst Hydrology

Determination of Hydraulic Diffusivity of a Limestone Aquifer Using Spectral Analysis Techniques

Hillol Guha, Ph.D., P.G., P.E.
The estimation of aquifer flow properties is commonly based on the application of a mechanical stress on the aquifer that causes a response in the flow field. By observing and measuring the response in the aquifer, hydrogeologic properties like transmissivity, hydraulic conductivity, and storativity can be inferred. The application of an anthropogenic aquifer stress (e.g., pumping or injection wells) is a widely-employed method of aquifer testing since the stress can be controlled and easily measured. Aquifer response to non-anthropogenic aquifer stresses, such as oceanic and earth tides, can also be used in the determination of aquifer properties, with the additional complication that the stress must first be well understood and quantified.

In a tidally influenced aquifer system, hydraulic diffusivity of the aquifer is proportional to the speed and amplitude at which a finite pressure pulse of the tide propagates through the aquifer system. This pressure pulse results in a spectral signature in observed groundwater wells. Frequency domain analysis of the tidally impacted groundwater wells and tides provides a meaningful and non-invasive approach to determination of hydraulic diffusivity of an aquifer.

Hydraulic diffusivity was estimated for a prolific aquifer in South Florida based on identification of tidally influenced spectral signature, lag time, and amplitude in groundwater wells and tides. An analytical solution of sea-aquifer model with a leaky semi-confining layer separating an overly unconfined aquifer from an underlying semiconfined aquifer was applied to estimate hydraulic diffusivity; based on the parameter values obtained from the spectral analysis technique. The hydraulic diffusivity values for the aquifer obtained from the spectral analysis techniques was within the same order of magnitude as that obtained from pumping tests.

Modeling and Evaluating the Influences of Class V Injection Wells on Urban Karst Hydrology

James Shelley
The response of a karst aquifer to storm events is often faster and more severe than that of a non-karst area. Many urban karst areas (UKAs) are plagued by groundwater flooding resulting from the highly permeable and diffusive aquifers. In UKAs, municipalities often struggle with flood management, because traditional strategies are ineffective. The City of Bowling Green (CoBG), Kentucky is a representative example of an area plagued by karst flooding, despite several decades of research and work done to understand and mitigate the issues. The CoBG, like many UKAs, uses Class V Injection Wells to reduce the severity of flooding. The overall effectiveness, siting, and flood impact of Injection Wells in UKA’s are still lacking; their influence on groundwater quantity and quality are evident from recurring problems of flooding and groundwater contamination. The purpose of this research to examine Class V Injection Wells in the CoBG to determine how Injection Well siting, design, and performance influence urban karst hydrology. The study uses high resolution monitoring, hydrograph recession analysis, geostatistical techniques, and hydrologic modeling (WMS-GSSHA) to evaluate Injection Well and spring responses during baseflow conditions and storm events. Through quantifying the hydrodynamic properties of the karst aquifer and the influences from the surrounding environment, it is possible to establish a relationship between precipitation events and the drainage capacity of the Injection Wells and the underlying karst system, as well as explore possible siting issues contributing to the efficiency of the system.

Managed Aquifer Recharge

ASR Generation: Generating Power During the Injection Cycle of an ASR Project.

Kent Madison
I will explain the process of generating electrical energy while injecting water during the ASR injection cycle using regenerative drives. I tested and then have been doing this in the worlds first agriculture ASR well and produce about 45 Kw during the injection cycle. This recovered energy has replaced our source water energy cost and reduced the total cost of our ASR project. The technology can be applied to any line shaft or submersible pump system that uses a VFD for the pump motors power source. I will show pictures of the prototype well and the results of the test and the installation of the production well and the equipment that is being used at that well.

Environmental Isotopes in Time Series Resolve Issues of Imported Water Recharge in Basin Fill Aquifer

Barry Hibbs, Ph.D.
The Coachella Canal was completed in 1948 to divert water from the Colorado River for use in Imperial Valley. The unlined canal recharged local aquifers, and wetlands expanded. Before and after canal lining in 2006, we collected samples from spring and well locations at Dos Palmas Preserve for comparison to canal and native groundwater sources.

Analysis of stable isotopes identifies distinct groups of water; one of nearly pure canal water with del 18O ranging from -11.3 to -11.9 and del 2H ranging from -84 to -95. A second of nearly pure native groundwater with del 18O ranging from -7.3 to -8.7 and del 2H ranging from -59.5 to -71. A third of mixtures of canal and native groundwater with del 18O ranging from -8.7 to -11.1 and del 2H ranging from -80 to -91. Most of the waters at the preserve are derived from Colorado River-fed canal water. Tritium and Carbon-14 support these interpretations. With lining of the canal, flow at the wetlands has decreased.

After canal lining a wetland mitigation project used artificial recharge to try to maintain adequate flow at springs. Artificial recharge is no more than 10-15% of the canal leakage that occurred before the canal was lined. A previous study in the late 1980s suggested that the San Andreas Springs at Dos Palmas Preserve was not connected to canal recharge, based on lack of tritium in flows. Regulators used this information to make plans for wetland mitigation. By 2003, our sampling showed that flow at San Andreas Spring was almost pure canal water, with bomb tritium detected. Canal water had not arrived in the late 1980s but had arrived by 2003. Our study points to the limitations of interpretations based on sampling in a moment in time, when a major retrofit to a groundwater basin is completed.

Sustainable Water Initiative For Tomorrow (SWIFT), Managed Aquifer Recharge Demonstration Project

Mark C. Lucas
The Coastal Plain Aquifer System of Virginia has experienced unsustainable groundwater withdrawals over the past several decades resulting in water level declines, regional land subsidence, and increasing vulnerability of supply wells to saltwater intrusion. Accordingly, the Hampton Roads Sanitation District (HRSD) is implementing the Sustainable Water Initiative for Tomorrow (SWIFT) which will add multiple advanced water treatment processes (AWTP) to select HRSD wastewater treatment facilities, producing a highly treated water that exceeds drinking water standards and is compatible with the receiving aquifer. At full‐scale, HRSD intends to recharge over 100 million gallons per day (mgd) of SWIFT Water into the Potomac Aquifer System (PAS) using managed aquifer recharge (MAR) wells. SWIFT will significantly reduce the nutrient load to the Chesapeake Bay, while benefitting the region by limiting saltwater intrusion, reducing land subsidence, and providing a sustainable source of groundwater, a necessity for continued economic expansion in the region.

The SWIFT Research Center (SWIFTRC), a concept demonstration project located at HRSD’s Nansemond Treatment Plant, constitutes a 1 MGD AWTP Facility that will recharge a test MAR well. While the SWIFTRC has multiple objectives, one involves providing a significant period of operational data to demonstrate the viability of MAR in the area. The SWIFTRC will start recharging the PAS in the second quarter of 2018. Operation of the SWIFTRC will provide preliminary experiences on the following:

  • Aquifer conditioning around the MAR Well to stabilize clay minerals in the PAS
  • Evaluating ability of the PAS to accept the recharge water over months of MAR operations
  • Stabilizing reactive, metal-bearing minerals, insitu
  • Geochemical reactions involving mixing or recharge/aquifer mineral relations
  • Estimating travel time and migrating recharge profile across the PAS
  • The ability of the PAS to attenuate constituents in the recharge (soil aquifer treatment).

Maximizing Efficiency in the Drilling Process Panel

Roger Renner, Gary Shawver and Fred Rothauge

Poster Session I

Consideration Factors of Production-Well Rehabilitation Assessment on Guam

Yong Sang Kim, PhD
Currently, Guam Waterworks Authority (GWA) produces 90% of the 45 MGD potable water from its main source, the Northern Guam Lens Aquifer (NGLA). GWA is currently managing 100 to 120 deep vertical production wells in this aquifer to meet the demand. However, many of these production wells are deteriorating from age with more than 50 years in operation, thus lifespan exceeded, maintenance is no longer economically viable, and production has become unsustainable. The NGLA is a composite to complex karst aquifer with a thick vadose zone, forming an uplifted plateau (> 60 m), and a highly anisotropic and permeable porous media. This aquifer bears a meteoric recharged freshwater lens atop saltwater, divided by a volcanic basement of 7 aquifer basins that form basal and parabasal zones with varying lens thickness in different regions. On Guam, rehabilitation of abandoned production well sites is a promising way of keeping freshwater production without further developing new well sites. However, some of rehabilitated production wells drilled adjacent to the old wells have resulted in severe reduction of water production. To investigate this issue, case study wells were chosen, and their construction, operation and rehabilitation history were analyzed. Based on the analysis, main consideration factors of production-well rehabilitation assessment were categorized.

Defensive Water Well Construction Regulations in the United States

Kimberly Miles
Water well construction standards and regulations favor optimizing water well production and longevity with defensiveness against contamination or pollutants. However, with ever-changing standards and aging well infrastructure, some regions are likely to be more susceptible to contamination than others. A survey of water well annular seal standards, as well as setback standards was completed for all 50 US states which measures, respectively, the average vertical and horizontal separation distance from surface contamination. Annular seal survey attributes include the minimum annular surface seal length, thickness and materials. Similarly, attributes for the setback distance survey compares commonly regulated pollution sources including any sewer line, a water tight septic tank, an animal or fowl enclosure, and a cesspool or seepage pit. Together, United States water well defensiveness against surface water contamination is assessed with respect to the selected standards’ A) stringency variance B) frequency of selected regulations and C) association with regional hydro geology, climate and population attributes.

Defining and Evaluating Production Capacity for an Island Aquifer

Daniel Superales
The Northern Guam Lens Aquifer (NGLA) provides 90% of Guam’s drinking water. Recent modeling results provided insights into how the existing water-production system might respond to new development and natural changes in recharge, but local policy makers and water managers have also asked “What is the ultimate volume of water that could be sustainably withdrawn from the aquifer if we had the best possible production system?” Answering this question requires, first, specifying an idealized production system—which we define as A notional production system that would employ existing technology and realign well locations to utilize the most favorable hydrologic locations of the aquifer, in the interest of enhancing production volume, water quality—or both—within a specified standard of salinity. Second, it requires reliable knowledge of the natural limits imposed by recharge and aquifer properties. We present preliminary results from a modeling study directed at estimating total production rates that could be achieved by about the same number as in the present system, set at the same depth, and pumping at the same average rate as the existing system, but in which well locations have been selected to utilize the most productive parts of the aquifer. Natural limits are imposed by specifying the same recharge and aquifer properties employed in the model of the existing system. Although an ideal production system as defined above is not likely achievable in practice, an estimate of the total production that could be obtained by such a system, for a specified salinity standard, provides helpful insights for long-term planning and future decisions regarding sustainable management of the NGLA.

Development of a Coupled Groundwater-Surface Water Model for Assessing the Impacts of Groundwater Pumping on Streamflow in the Middle Rio Grande Basin

Marjan Monfarednasab
This study is focused on the Middle Rio Grande basin which extends from Elephant Butte Reservoir in New Mexico 297 kilometers to Ft. Quitman on the US (Texas)-Mexico (Chihuahua) border. This region is on top five most water-stressed places globally due to water scarcity. The channel of the Rio Grande is connected hydraulically to an underlying alluvial aquifer. Extraction of groundwater from the alluvial aquifer is suspected to substantially affect streamflow in the Rio Grande. This study is an attempt to simulate this system to provide information for water managers and other local policy makers.

A one-dimensional (1D) flow model has been developed by solving the groundwater flow equation with finite differences, estimating steady-state routing of flow in the Rio Grande, and coupling the groundwater and streamflow models with Darcy’s law model of channel-alluvial aquifer exchange. This model is simulating conjunctive groundwater and surface water considering Rio Grande River flow and irrigational multi-branched canals for agricultural usage, and pumping for both municipal and agricultural usage along all over the basins. The 1D flow model has been coded in MATLAB, where the groundwater flow, streamflow, and channel exchange equations are solved iteratively. Calibration of hydraulic conductivity, aquifer bottom, and return flow fractions occurs by minimizing the sum of the squares of the residuals between modeled and observed groundwater levels and streamflows from January 1993 to January 2014. Groundwater (alluvial) database is attributed from GSGS/New Mexico monitoring wells which is consisting of more than three thousands observation points throughout the calibration period.

This work will be useful to predict the future of middle Rio Grande. This will shows the effect of continuous regional pumpings on the aquifer, whether the over pumping of alluvial aquifer accompanied by channel’s losses will adapt to a sustainable system

Dynamic Response of the Freshwater Lens to Natural Variations in Recharge, Northern Guam Lens Aquifer

Bekah Dougher
The Northern Guam Lens Aquifer (NGLA), is a deep karst limestone aquifer that supplies more than 90% of the island’s 45 MGD of potable water. As Guam prepares for economic growth, the growing demand for water is a major concern. The quantity of groundwater available for extraction can be measured in terms of the freshwater lens thickness. Lens thickness can be measured directly from well salinity profiles and inferred indirectly from water levels. The amount of recharge that replenishes the aquifer depends primarily on seasonal and inter-annual changes in rainfall as well as on the porous media properties, recharge, and discharge. The Yigo-Tumon Aquifer Basin, the most productive (21 MGD) of 6 aquifer basins in the NGLA, has 3 deep observation and 3 observation water level wells used in this study. Time series CTD data was evaluated in order to determine lens response to recharge and drought. A multi-variable time-series analysis was made to align possible communicative data from ONI, rainfall, and sea level to the phreatic graphs. Lag and attenuation of lens response to rainfall-recharge was examined to determine lens stability. The goal of this project was to interpret the response of the lens to natural climate variations, given the ongoing well production, through observation of temporal lens and saltwater transition zone dynamics in response to excess recharge and extensive drought. The single most important question is how much of rainfall constitutes effective recharge, actual groundwater recharge that thickens the freshwater lens. This research provides an empirical basis for estimating the percent of rainfall actually goes into lens storage under certain conditions. It provides an observational baseline for which the accuracy of past, present, and future modeling studies can be evaluated and by which future modeling studies can be reliably parameterized.

Environmental Isotopes Delineate Recharge Sources in the Coachella Valley Aquifer, California

Jonathan Arriaza
Groundwater in the Coachella Valley is a critical resource satisfying water demands in Palm Springs, other nearby communities, and farms. To support sustainability planning, this study was conducted to determine areas and sources of groundwater recharge in the Coachella Valley Aquifer. Field data collection included water sampling for stable water isotopes and major ions at feeder tributaries and water wells in subbasins in the Coachella Valley Aquifer, and integration of published radioisotope and stable isotope data collected by water purveyors, USGS and other entities. Springs and surface flows were also collected at different elevations in the San Bernardino and San Jacinto Mountains at tributary streams that feed into the Coachella Valley Aquifer. Data indicate variable stable water isotope signatures related to origin and source of recharge water, suggesting that subbasins are recharged by precipitation falling closer to valley floors and peripheral mountain fronts, rather than from runoff of rainfall and snowmelt from high elevations in the San Bernardino and San Jacinto Mountains. Carbon-14 and tritium data reinforce these interpretations. In addition, recharge in different subbasins in the Coachella Valley Aquifer suggest unique tributary inputs in the upper parts of the subbasins, along with water mixing due to groundwater underflow between subbasins. Recharge by water imported from the Colorado River was also detected, but is limited to areas near recharge basins in the western part of the Coachella Valley Aquifer where recharge basins have existed for decades.

Integrating hydrogeology with psychology for management in a groundwater-dependent community

Will Brewer
Understanding stakeholder comprehension and motivations are important in promoting resource conservation and responsible use. Groundwater resources are notoriously misconceptualized in ways not conducive to conservation behaviors, such as envisioning groundwater systems as underground lakes and streams. The current project seeks to integrate commonly-applied principles of psychological research and the hydrogeological understanding of the Northern Segment of the Edwards Balcones Fault Zone aquifer in Central Texas to better understand water use behaviors for the aquifer and an associated spring complex in the village of Salado. This spring complex is important in that it is the only known habitat of a federally-listed Threatened salamander species (Eurycea chisholmensis), as well as one of the main tourism draws in the village. In addition to its ecological and recreational importance, spring flow is a management measure for the local groundwater conservation district.

Electronic surveys and in-field observation are the primary methods of data collection. The surveys facilitate examination of current attitudes towards groundwater in the area and indicate the level of familiarity with groundwater mechanics for the study population. In-field observational data collected at the springs complex contextualize results obtained from completed surveys and reveal potential biases that tourists might have on average spring use. Partnering with the local groundwater conservation district ensures that survey questions will be relevant, and allows the data gathered to be effectively applied to future education and outreach efforts. In understanding the current groundwater usage in the area, it will be possible to better prepare for and promote more effective conservation strategies. Results of this study can also inform future tactics for educating the general public about groundwater.

Investigation of Textile Dyes as a Groundwater Contaminant in Mandalay Myanmar

Surya Freeman
Textile dyeing of traditional garments has occurred in the Amarapura Township of Mandalay, Myanmar since 1822, transitioning from natural to chemical dyes in the early 1900’s. With no current wastewater treatment facilities in Mandalay, dye effluents mix with other wastewaters in unlined canals dug near peoples’ homes and discharge into local waterways. As locals rely heavily on dug and tube wells near these canals for drinking, bathing, and cooking, this industry poses a major health hazard to people in the region. The objective of this study is to identify and quantify the concentrations of major ions and heavy metals found in textile dye effluents and determine the impact on local groundwater. Water samples from each stage of the dye process have helped to identify the previously unknown composition of dye powders, while samples collected from tube and dug wells, both at dyeing sites and upgradient have been used to assess the geochemistry of contaminated and background water sources. Preliminary results identified heavy metals in varying concentrations throughout each step of this process. The highest levels of heavy metals were found at the openings of discharge pipes, where multiple dyes mix together before spreading to the surrounding environment. Heavily reducing environments were also identified in the dye mixtures and nearby tube wells, resulting from the high basicity of the mixtures. High electrical conductivity was recorded in both dye bath mixtures and local tube wells due to the addition of sodium hydroxide in one of the initial steps of dyeing to strengthen color fastness. These results are not seen in samples taken from upgradient of the select dyeing operations. Textile dyeing is a major source of pollution and a health hazard to the people here, however locals are not readily connecting the dye practices to the issues with their drinking water.

Strontium Isotope and Major Ion Geochemistry of Yalahau Fracture Zone Waters, Yucatán Peninsula, Mexico

Jessica McKay
The Yalahau Region, located in the northeastern portion of the Yucatán Peninsula, hosts a series of elongated depressions trending north/south in the direction of Isla Holbox, identified as the Yalahau Fracture Zone (aka Holbox). Previous studies have explored the geomorphology and various hydrologic characteristics of the Yucatan Peninsula; however, there is a gap in data concerning the interior region where the Yalahau fractures are located. Strontium isotope and major ion geochemistry data on the surface and groundwater of this region will serve as a hydrogeochemical fingerprint to aid in constraining the hydrological boundaries, determining direction of groundwater flow, and characterizing hydrogeochemical processes that impact the composition of the groundwater within the region. 87Sr/86Sr isotope ratios and ion concentrations are expected to differ from previously published data on surrounding aquifers and flow regimes, with the potential to distinguish different areas of groundwater recharge, storage, and flow direction. Gaining an understanding of the geochemical processes and the identification of the source region(s) of the waters is critical in determining the impact of various activities (e.g. extensive tourism, drinking water withdrawal, wastewater discharge/injection) that occur within the Yucatán Peninsula. The results of this study may have a significant effect on the contaminant risk of municipal water supplies that face northern coastal cities of the Yucatán including Chiquilá and the increasingly popular tourist destination, Isla Holbox.

Water Quality & sUAS Photogrammetry of Boeng Cheung Ek Treatment Wetland, Phnom Penh, Cambodia

Samuel Mallow
Boeng Cheung Ek wetland is a large, peri-urban, free water surface, wastewater treatment wetland that services approximately 90% of combined storm water and untreated municipal wastewater from the city of Phnom Penh, Cambodia. Flooded area in the wetland basin cycles seasonally between 20 km2 and 13 km2 during the monsoon season. Untreated wastewater input is an average of 2.04 m3/s during the dry season with a maximum of 12 m3/s during storm events. The objective of this study is to characterize the spatiotemporal variability of contaminants in wetland surface water and determine whether infiltration to groundwater has occurred. Significant communities adjacent to the wetland still rely on household wells for drinking water. Nitrate, ammonia, phosphate, potassium, chloride, E. coli, heavy metals, H and O isotopes, and physicochemical parameters were determined for three sampling seasons: Jul-2017, Aug-2017, and Jan-2018. Of 10 household and community wells sampled, two wells located 180 m apart had high levels of chloride indicating contamination by wastewater. The difference in concentration between inflow at two wastewater pumping stations and outflow from the wetland via two outlet streams reflected reductions in the range of 40-88% (ammonia) and 43-87% (phosphate). Additionally, the study presents the potential of sUAS photogrammetry for inexpensively producing high resolution digital elevation models. A 1.2 km2 DEM with an average ground sampling distance of only 6.67 cm was compared to eight RTK-GPS ground control points yielding a mean vertical error of 4.96 m and standard deviation of 0.67 m. Data from this emerging technology has applications including referencing well elevation, measuring surface water level, and serving as an input for flood modeling. Plans exist to fill in 72% of the wetland for development. We hope this research will help inform the sustainable management of wastewater in the city.

Poster Session II

Advancements to the EZVI Technology: Optimization of Biotic and Abiotic Processes and Improved Implementability

Jim Mueller
Background/Objectives: The remediation of dense non-aqueous phase liquids (DNAPLs) can be complicated by the associated physical and chemical properties of the contaminants. The potential effectiveness of ZVI for remediation of groundwater impacted by chlorinated solvents has been documented since the early 1990s. The chemical transformation with ZVI occurs via aqueous-phase reactions on particle surfaces and therefore involves at least three steps: (a) contaminant adsorption on the ZVI particle surface, (b) reaction at the surface, and (c) desorption of the transformation product. The ZVI mediated transformation processes described above are relevant for dissolved phase contaminant destruction, as the ZVI requires a hydrogen donor (e.g. H2O) for the abiotic reactions to proceed. Because DNAPL is not in the dissolved phase and has a hydrophobic physical chemistry, injection of ZVI slurries into source areas will not provide direct destruction of source material.

Approach/Activities: Emulsified ZVI (EZVI) technology provides a solution to these problems. First, it is engineered to enable maximum contact with source materials, while including ZVI suspended within water (hydrogen donor) so that direct DNAPL destruction is possible using ZVI technology. EZVI also combines food grade vegetable oil (VO) with a surfactant, elemental iron and water in a specific physical structure to enable direct DNAPL destruction utilizing a combination of abiotic and biotic processes while leveraging contaminant physical chemistry. The key innovation surrounding genuine EZVI technology is the structure of the emulsion. The structure of the EZVI technology enables; Miscibility with DNAPLs in situ; Continuous Sequestration (phase partitioning) of COI into outer VO membrane (decreased COI mass flux); Encapsulates ZVI so that it only reacts with COIs with hydrophobic physical chemistry; and Provides a long term hydrogen source for biostimulation downgradient from the source area.

Advancing Magnetic Resonance Geophysical Methods to Characterize Groundwater Systems

David Walsh, Ph.D.
Magnetic resonance geophysical methods allow efficient in-situ characterization of key hydrogeologic properties including porosity, pore size, permeability, and specific yield. Precise downhole measurements can be carried out with small-diameter borehole tools and non-invasive profiling can be achieved using multi-channel surface instrumentation. Recent hardware advancements have focused on accelerating measurements speed, reducing impacts of near-borehole disturbance, and reducing hardware cost. These advancements have enabled use of borehole and surface magnetic resonance across a wider range of environmental and geologic conditions, with applications in water resources, environmental remediation, engineering, and mining. In addition to characterization of static hydrogeologic properties, we have recently investigated methodologies to characterize dynamic systems. Extending from advanced techniques in medical MRI, we have tested implementation of magnetic resonance measurements that are synchronized with fluid injection. These experiments aim to determine dynamic parameters including flow velocity, flow distribution, and dispersion. Meso-scale laboratory experiments in a PVC flow cell have yielded promising results indicating the ability to characterize flow inside the formation both qualitatively and quantitatively. Dynamic experiments on unnsaturated systems undergoing drying also demonstrate the capability to monitor fractionation of water between different pore sizes as saturation decreases. Field implementation of these flow injection methods will combine borehole magnetic resonance measurements with specially designed packer systems.

Comparison of Sr-90 and Y-90 concentrations in groundwater predicted by four different models

Sohan Chouhan
Canadian Nuclear Laboratories recently completed a study comparing modelling software used in performing environmental risk assessment of its Sites. This study assessed contaminant migration through a shallow sandy aquifer on the Chalk River Laboratories site.

Sr-90 and its daughter Y-90 radionuclides were considered in this comparison. For this scenario, it was assumed that a one-year pulse of 32 TBq of Sr-90 was released over an area of 115 m2 at the water table, thus transport in the unsaturated subsurface zone was not considered.

The groundwater transport path was assumed to consist of two parts in series. The first part was 140 m through silty, very-fine sand, and the second was 310 m through fine-medium sand. During transport, the radionuclides were assumed to undergo one-dimensional advection, three-dimensional dispersion, and linear equilibrium sorption. The groundwater was assumed to discharge to a pond and to a well located 1 m upstream from the pond. The well was assumed to be centred on the contaminant plume and did not significantly alter the natural groundwater flow.

The plume ground water concentrations were predicted using RESRAD-OFFSITE Version 3.1, AMBER-LI602, SYVAC3-CC4 Version CC4.09.1, and ECOLEGO-EXERCISE2. The peak of predicted well and pond concentrations of Sr-90 varied from 319 Bq/L predicted by RESRAD-OFFSITE to 1090 Bq/L predicted by SYVAC3-CC4, with ECOLEGO-EXERCISE2 and AMBER-LI602 predictions being in the middle. The peak arrival times varied from 140 years predicted by ECOLEGO-EXERCISE2 to 180 years predicted by RESRAD-OFFSITE, with AMBER-LI602 and SYVAC3-CC4 predictions being in the middle. Similar prediction variations were found for Y-90. Broad reasons for differences in the predictions were identified. This comparison provides an excellent estimate of the magnitude of uncertainties in model predictions for this scenario.

Progress made from work currently being done on including predictions using Visual MODFLOW Flex into the comparison may also be discussed.

Contaminants Introduced to Treatment Systems from Components and Materials Impact Regulated Discharge

Steve Gregory
During the last 16 years of groundwater remediation activities at Lawrence Livermore National Laboratory’s Site 300 explosives test site, there have been multiple cases of contaminants being inadvertently introduced to groundwater treatment systems from treatment system components, treatment system construction materials, and treatment media. These included plasticizers diffusing from nylon tubing used for extraction well-field pumps, residual organic compounds from the use of PVC glue and thread adhesives, residual organic contaminants in ion-exchange resin left over from the manufacturing process, and internal contamination of treatment media vessels from internal anti-corrosion coatings. Most cases were discovered during initial startup of a new treatment system, after system shutdown periods, or at cyclically operated treatment systems where the water had longer residence times with the contaminated materials. It is not safe to assume that materials provided by companies catering to environmental cleanup are free of contaminants and ready for immediate use. It was surprising to learn that many of these supply companies list accreditation with NSF/ANSI (NSF International Standard/American National Standard), and in particular Standard 61, Drinking Water System Components. This standard establishes the minimum requirements for the control of potential adverse human health effects from products that contact drinking water. LLNL has worked extensively to minimize the impacts of introduced contamination. Tubing materials were chemically evaluated, and test stands were used to evaluate glues and sealants. The arrangement of treatment media vessels at groundwater treatment systems were modified to reduce releases of potential contaminants. Ion-exchange resin leachate testing methods were developed and special procurement contracts were established to include acceptance criteria for the purchase of all ion-exchange resins. All treatment media vessels are cleaned and then soak tested to evaluate any internal contamination prior to being put into use.

Fate of Emerging Contaminants During Infiltration of Untreated Wastewater in Mezquital Valley, Mexico

Luis E. Lesser, Ph.D.
The Mezquital Valley is the world's oldest and largest example of usage of untreated wastewater for agricultural irrigation. North of Mexico City, the Mezquital Valley receives, since the 1950s, untreated wastewater through three different main sewage drains from Mexico City (an open canal and two deep sewage systems, with a third deep sewage close to completion). Currently, more than 45 ha are irrigated with approximately 50 m3/s of this untreated wastewater in the Mezquital Valley. Eighty one percent of the main canals, and 52% of secondary canals are unlined, with water infiltrating directly into the shallow aquifer. Because of the high artificial recharge in the area, groundwater is extracted for human consumption from the deeper aquifers.

This study analyzed 218 organic microcontaminants in wastewater canals, springs and groundwater from the Mezquital Valley. Five volatile organic compounds (VOCs) and 9 semi-volatile organic compounds (SVOCs) were detected in the wastewater used for irrigation. Only 2 SVOCs were detected in all the wastewater canals and groundwater sources, whereas no VOCs were detected in groundwater and springs.

Of the 118 pharmaceutically active compounds (PhACs) and 7 reproductive hormones measured, 65 PhACs and 3 hormones were detected in the wastewater. In groundwater sources, 23 PhACs were detected. Most of these compounds have low concentrations compared to those detected in canals. There were only few detections and at lower concentrations in the deeper aquifers. These results suggest that the subsurface acts as a filter, adsorbing and degrading most of the organic pollutant content in the infiltrated wastewater. A new wastewater treatment plant (PTAR Atotonilco) is being built to treat the wastewater prior to its release to the Mezquital Valley. The geochemical changes that this cleaner water will produce when infiltrated into the aquifer have not been assessed yet.

Guam Water Resources Monitoring Program

Kaylyn Bautista
The water resource monitoring program for the Northern Guam Lens Aquifer (NGLA), designated a Sole Source Aquifer in 1978 by the U.S. EPA, had been established in the 1950s by the USGS. However, in the 1990s, this program was forced to downsize when funding from the local government could not be met, which resulted in data disruption to deep well monitoring for saltwater intrusion in the north and stream gage data in the south. In 1998 the Comprehensive Water Monitoring Program (Guam Public Law 24-161) became a permanent program of the Water and Environmental Research Institute (WERI) of the Western Pacific and resulted in the refurbishment of the deep monitoring wells and a renewed program of water resource monitoring on Guam. In the same year, the Guam Hydrologic Survey (Guam Public Law 24-247) was made a permanent program, administered by WERI, to develop an inter-agency cooperation for gathering and publicly providing water and environmental information. Current withdrawals from production wells estimate to 40 Mgal/d. Over the next decade, population growth, inclusive of the proposed military forces relocation, projects a production increase as much as 25 percent. Increased withdrawals, in the long-term, were modeled to result in a decline in water levels and a rise in the freshwater-saltwater transition zone. To assist with water-resource management, an inter-agency framework for information sharing and decision making has been established with a Memorandum of Understanding, signed in 2010, under the Monitoring System Expansion and Rehabilitation Program. 7 new deep monitoring wells will be drilled, and 12 existing monitoring wells will be rehabilitated to expand groundwater monitoring from only two NGLA sub-basins to include the remaining four sub-basins. As partners in the island's technical/scientific experts group, WERI and the USGS will assume data collection, analyses, and reporting, to provide best practices for sustainable management.

Hydrogeologic Map of the Northern Guam Lens Aquifer

John Jenson, PhD
The Northern Guam Lens Aquifer (NGLA) produces 90% (42/45 MGD) of Guam’s potable water for its 160,000 civilian and military residents and more than 1.3 million annual visitors. Plans are underway to increase the military presence, with concomitant increases in economic activity and demand for water. The NGLA is an uplifted Carbonate Island Karst aquifer, in which the porous, water-bearing limestone bedrock is partitioned into six groundwater basins by the much lower-permeability volcaniclastic basement rock that forms subterranean rises, ridges, and valleys above sea level beneath the limestone. Within each basin, freshwater is found in three groundwater zones: 1) the basal zone, in which the buoyantly-supported freshwater lens flows from the basement partitions in the interior toward the coast atop underlying saltwater; 2) the para-basal zone, at the head of the lens, where freshwater is underlain by the basement aquiclude and whence it enters the basal lens; and 3) the supra-basal zone, in which perched water flows down the aquifer-aquiclude contact into the para-basal zone ringing the flank of the basement where it rises above sea level. Field and modeling studies indicate that the porous matrix of the young (Miocene to Pleistocene) limestone supports storage of 0.20 and higher. Flow paths can be strongly controlled by regional-scale fractures and conduits in this triple-porosity aquifer. Successful modeling, exploration, well design, production management, and aquifer protection strategies depend on having a reliable hydrogeologic map of the aquifer, showing the zones within the basins and the expected flow paths. This presentation shows a start-of-the art map with the modeled water table and inferred boundaries of the basins and zones based on basement topography derived from borehole and geophysical data. The NGLA map has become an essential tool for local water developers and managers, federal and local regulators and planners, and water resources educators.

Management of Spent PFAS Adsorption Materials and Concentrates in Australia – Commercially Viable Solutions

Richard Carran, BSc, BBS, MSc
Background/Objectives.

Perfluorinated Compounds (PFCs) have emerged as pollutants of concern to human health and the environment. Leading technologies for PFC removal from water in Australia include; fractionation, adsorption, and ion-exchange. The effectiveness of which are extensively researched and debated elsewhere.

Due to the strong chemical bond between the Carbon and Fluorine in PFCs, most water treatment methodologies do not destroy the PFC’s, and result in a waste product (concentrate or spent adsorption materials) requiring disposal or further treatment. Typically, this waste product is stockpiled until a destruction solution is available or disposed of to landfill.

Proven technologies for the destruction of PFCs are very limited. Commercially viable treatment options available in Australia include; pyrolysis and oxidative thermal destruction, and thermal desorption.

Enviropacific have successfully treated PFC contaminated soil via thermal desorption and are investigating the practicability of treating spent PFC adsorption materials and PFC concentrates.

Approach/Activities.

Enviropacific utilises a lab-scale apparatus, that reproduces the operating conditions in a direct-fired thermal treatment plant, to determine if thermal desorption is an effective destruction method for spent PFC adsorption materials and concentrates.

Following successful lab-scale trials, large-scale trials using an operational direct-fired thermal treatment plant will determine the scalability and reproducibility of the desorption process for this application.

Results/Lessons Learned.

Enviropacific have successfully proven PFC desorption from soil, determining that temperatures above 400°C with residence time of greater than 10 minutes are required.

It is expected that the results of the lab-scale trial will determine the optimum operating conditions required to successfully desorb PFCs from spent adsorption materials and concentrates, sufficient enough to meet relevant state and federal treatment criteria.

Large-scale trials will confirm the desorption method as a commercially viable solution for managing spent PFC adsorption materials and concentrates.

Modeling Permafrost Aggradation and Thaw in a Peat Plateau Wetland Complex

Robert A. Schincariol, Ph.D., P.Eng., P.Geo.
Permafrost degradation strongly influences the hydrology and ecology of northern watersheds. In wetland-dominated zones of discontinuous permafrost, permafrost occurs below tree-covered peat plateaus where the tree-canopy and vadose zone insulate and preserve the permafrost. As the permafrost thaws, peat plateaus shrink, the landscape transitions into unforested wetlands, and hydrologic surface and subsurface connectivity increases. The resultant permafrost-degraded areas comprise large portions of the drainage density of sub-arctic basins and alter the region’s water and energy balances. To better understand the fundamental processes affecting permafrost thaw, a three-dimensional finite element numerical model is constructed for a peat plateau wetland complex in Northwest Territories, Canada (61°18'N, 121°18'W). FEFLOW groundwater flow and heat transport modeling software is used in conjunction with the piFreeze plug-in, to account for phase changes between ice and water. Representative permafrost is developed with both steady-state and transient approaches. The steady-state approach uses a ground temperature of -2.5 °C and 1.3 °C applied over the modern-day permafrost plateau and wetlands, respectively. Actual permafrost evolution, to current conditions, would require 100’s of years of climate variations over an evolving landscape. To properly develop a subsurface environment which matches field data collected since 1994, the model simulations are conducted in transient mode. The transient approach applies daily climatic data over the plateau between 1875 and 2015; the Simultaneous Heat and Water model (SHAW) is used to calculate ground temperatures and infiltration rates. Transient simulations are computationally demanding for the 2.4 million node model. Simulations advance at 2 to 3 years per 24 CPU hours on advanced workstations. Modeling permafrost aggradation / degradation will allow for the testing of remedial measures, such as mulching and borehole heat exchangers, to stabilize permafrost in high value infrastructure environments.

Keywords: permafrost degradation, peat plateau, heat and water movement, ecohydrology

Proposed Use of Long Screened Test Wells in Environmental and Groundwater Resource Investigations

Noah Heller
We present two case studies where long screened wells (150 meters to 300 meters deep) were used to delineate the vertical extent of total dissolved solids and arsenic in the surrounding aquifers, respectively. The cost benefits included eliminating the requirement for multiple short screened wells to characterize the same vertical extent of formation, and to characterize the problem under actual pumping and hydraulic head conditions. In the TDS study, high resolution, vertical delineation led to a significant cost reduction in the use of reverse osmosis treatment for cooling water at a power plant facility as well as reduced costs in power plant operations. In the second case, the vertical delineation provided a clear understanding about arsenic distribution in the aquifers providing groundwater to the consumer’s public water supply and enabling a decision to be made about using well modification or treatment to make the well compliant with the regulatory standard (10 ug/L). In both cases, “Intra Borehole Flow” bias was avoided by pumping the wells at a high enough rate to overcome intra well mixing. For each test, depth dependent inflow velocity measurements and water chemistry samples were collocated at each depth and then flow-weighted to determine the zonal flow and chemistry contributions. Use of the Tracer Flowmeter and Depth Dependent Sampler method developed by the USGS made it possible to collect the equivalent of samples from 30 monitoring wells in the TDS study, in only six days. In the arsenic study, the equivalent of 10 zones were obtained in two days.

Role of Geological Heterogeneity in Poroelastic Deformation of Geologic Medium due to Groundwater Extraction

Ajit Joshi
Land subsidence caused by groundwater extraction has been a major issue for developments in coastal cities where global climate change and sea level rise can exacerbate the situation. Data from satellite observations and leveling survey measurements from the Kujukuri region in Chiba Prefecture in Japan showed land subsidence have continued from past few decades until now because of extraction of methane dissolved in groundwater. For accurate prediction from numerical model, it must represent realistic subsurface conditions. Observations of outcrops from field site showed gradual fining upward/ coarsening upward cycles of vertical gradation with sediment size ranging from sandstone to siltstone/mudstone. This formation-scale sediment heterogeneity could affect hydraulic properties of geologic medium and affect its deformation.

Present research studied effect of vertical heterogeneity on poroelastic deformation of geologic medium and predicted land subsidence caused by groundwater extraction. One-dimensional numerical modeling of groundwater flow and sediment deformation was done by solving mass balance equations with Darcy’s flow mechanics for water-saturated poroelastic medium. Porosity and permeability of the medium were related using Kozeny-Carman equation. Simulations were conducted for an idealized 130 m thick geologic medium having a vertical sediment gradation ranging from coarse-grained sandstone at bottom to fine-grained siltstone (or mudstone) at top. A constant water production rate was assigned over a 50 m interval at the bottom. Simulations with heterogeneous sandstone/mudstone sequences were compared to homogenous sequences. The comparisons showed that deformation was higher for mudstone compared to sandstone due to less permeable and more compressible nature of mudstone. Another simulation was done using litho-stratigraphic section from the field site to calibrate model prediction with a field deformation data. Land subsidence prediction from the model showed a good match with deformation data from field measurements. Future research will be focused on studying deformation behavior of a poroelastic medium saturated with multiple fluids(water/methane).

Tetrachloroethylene Groundwater Remediation In A Dolomitic Limestone Aquifer Using Injectable Zero Valent Iron

Dawn Knipe, L.P.G.
Tetrachloroethylene (PCE) and its daughter products were detected in the shallow portion of a fractured dolomitic aquifer system between five (5) and 30 feet below ground surface (ft bgs) at a former dry cleaning facility located in Indiana. Geophysical surveys were conducted to guide investigation activities and subsequently used to direct monitoring well placement. Zero valent iron (ZVI) along with a carbon substrate was chosen as the remedial technology. A Pilot Test was completed to evaluate the chemical selection/injection technology and the ability of the fractured bedrock to accept the chemical injections. Based on the Pilot Test results, the combination of ZVI and carbon substrate was selected for the full-scale chemical injection. Full-scale injections were subsequently implemented at 21 injection locations. Following full-scale injection, a methane survey was completed to alleviate state agency concerns over production of excessive levels of methane. The remedial strategy has been a success at the Site with substantial contaminant reduction in a challenging fractured bedrock media, a strategy that can be used at other impacted bedrock Sites.

Thermal Release Of Arsenic, Metals And Organic Compounds From Aquifer Sediments During In Situ Bitumen Extraction

Michael Moncur, PhD
The Athabasca Oil Sands (AOS) deposits in Alberta, Canada, are estimated to contain approximately 1700 billion barrels of oil of which 170 billion barrels are recoverable with existing technology. Only 20 % of the oil sands are recoverable through surface mining, whereas the remaining 80 % of the oil sands are located at depths (>80m) that require in situ methods. Bitumen is immobile at reservoir temperatures, however when heated to 200°C, it approaches the viscosity of water. To reduce the viscosity of bitumen for recovery, enhanced thermal recovery methods (e.g. steam injection) are used to increase the temperature of the bitumen to decrease its viscosity. The transfer of radiant and advective heat from steam injection well casings to the adjacent aquifer sediments can increase groundwater temperatures, increasing the solubility of some mineral phases. The dissolution of minerals or mobilization of poorly sorbed elements from the sediments may release arsenic and other metal(oid)s to the groundwater. These mobilized elements and heat may be transported down-gradient, away from the injector well, along groundwater flowpaths. This study heated glacial fluvial aquifer sediments from the AOS under controlled laboratory conditions with the objective of gaining a better understanding of the mechanisms for the release of dissolved metal(loid)s and organic compounds to groundwater. Heating of the sediments and water showed a rapid release of As, with As(III) being the dominate mobile species. Other dissolved ions (Ba, Li, Mo, Si and Al) and dissolved organic carbon (including organic acids) were also released, and some of these elements could be useful for tracing groundwater thermal plumes. The information from these thermal tests is capable of identifying the aquifers with the greatest potential for impacting water quality or releasing gases, which would allow these aquifers to be targeted for more intensive monitoring and risk assessment.

Procurement Practices in the Groundwater Industry

Fred Rothauge, David Kaminski and Jeffrey Holden, PE, LSP, LEP

Risk Management for the 21st Century Business

Don Cleveland, Steve Smith, Linda Colasurdo, Courtnee Stevenson and Bonnie North

Supply Chain Survival in the Age of Amazon

Greg Beach, David Henrich, CWD/PI, CVCLD and Randy Carnes

Sustainability and Planning

Central Coast Blue: Creating a Sustainable Groundwater Supply and Combating the Threat of Seawater Intrusion

Michael Cruikshank, PG, CHG
Groundwater Basins along the Central Coast of California have been severely stressed due to the historic drought conditions which has resulted in declining groundwater levels and in some cases intensified the threat of seawater intrusion. The Northern Cities Management Area (NCMA) of the Santa Maria Groundwater Basin (SMGB), located along the coast of Southern San Luis Obispo County, is a coastal aquifer that has observed increased chloride concentrations in previous prolonged droughts and been drastically impacted by the current drought. The NCMA has significantly reduced groundwater pumping to combat the threat of seawater intrusion and groundwater levels have continued to decline. As a result of the decreased groundwater pumping, the NCMA have increased their reliance on local surface water reservoirs (Lopez Lake Reservoir) and imported supplies (State Water Project) which are also sensitive to drought conditions, to meet the water demands of the NCMA.

Central Coast Blue is a regional recycled water project that will develop a sustainable water supply and protect the SMGB from seawater intrusion by creating a seawater barrier through a series of wells that will inject purified recycled water. Currently, the water from the Pismo Beach Wastewater Treatment Plant (WWTP) and the South San Luis Obispo County Sanitation District (SSLOCSD) WWTPs is being treated and discharged to the ocean.

This talk will focus on how the Central Coast Blue project will optimize groundwater production and create a drought proof source of supply to ensure that reliable water supplies will be available for future extended droughts though the use of a calibrated groundwater model and the development of an adaptive basin level response plan.

Chasing Sustainability: Establishing Management Goals and Thresholds

Leslie Dumas, PE
Effective January 1, 2015, the Sustainable Groundwater Management Act (or SGMA) establishes a new structure for sustaining groundwater in California and, for the first time, attempts to locally manage groundwater use. SGMA requires preparation of Groundwater Sustainability Plans (or GSPs) by Groundwater Sustainability Agencies (or GSAS), which include a definition of basin sustainability and a plan to achieve the desired sustainability goal. For the 150+ groundwater basins that are required to comply with SGMA, this will means not only defining sustainability in terms of six distinct sustainability indicators, but determining the thresholds or limits by which the groundwater basins will be managed. SGMA requires the development of minimum thresholds and measurable objectives for each of the six sustainability criteria, but also requires that these thresholds be developed in an open and transparent process considering all the users of groundwater in the basin (including the environment) AND that these thresholds be coordinated between subbasins to ensure that they do not result in adverse impacts outside the subbasin managed by the GSP. For Delta-Mendota Subbasin, with six GSPs, 23 GSAs and eight adjoining subbasins, developing these thresholds is an exercise in both science and coordination on many scales. This presentation will summarize the efforts put forth to develop these sustainability goals and thresholds and how it was achieved in the context of a much larger, regional coordination effort.

The Evolving Landscape of Groundwater Management in California

Timothy K. Parker, PG, CEG, CHG
California passed the Sustainable Groundwater Management Act in 2014. The SGMA requires that (1) new Groundwater Sustainability Agencies form by June 2016 in all SGMA high and medium priority basins, (2) new groundwater sustainability plans (GSP) by January 2020 (critically overdrafted basins) or 2022 (other basins), and (3) have sustainable groundwater management within 20 years of GSP adoption. Th4e GSPs are required to include description of the basin hydrogeologic conceptual model, water budget and groundwater conditions, development of minimum thresholds, measureable objectives, and interim milestones to achieve sustainability, description of projects and management actions, and a funding plan. The SGMA defines six sustainability indicators for the development of sustainable management criteria: (1) chronic lowering of groundwater levels (2) reduction of groundwater storage, (3) seawater intrusion, (4) water quality degradation, (5) land subsidence from groundwater extraction, and (6) depletion of interconnected surface water from groundwater pumping. Some of the challenges to complying with SGMA and achieving sustainability include that many GSAs were formed within basins, making it more difficult to assure collaboration, cooperation and consistency in data used and assumptions. Additionally, assessing surface water depletion from groundwater extraction is technically difficult, especially considering the lack of adequate monitoring networks for stream flow and shallow groundwater, and understanding where streams are losing and gaining. Addressing the water quality sustainability indicator will also be particularly challenging because SGMA is silent on what is required, there is no state guidance, and there are many regulations related to contamination. A brief description of the California hydrogeologic and policy setting will be presented along with statewide groundwater depletion conditions, a brief review of the requirements of SGMA, new regulations, progress to date, and identification of key challenges and opportunities as California works to meet SGMA mandates.

Using Private Wells to Cost-Effectively Complement and Extend Groundwater-Level Monitoring Networks, Build Consensus and Facilitate Sustainable Management

Marian Singer, Co-founder & CEO
Groundwater managers, private firms, consultants, and research scientists are expanding groundwaterlevel monitoring networks to provide greater spatial and temporal density of groundwater-level data required to meet new and changing sustainability goals. The primary limitations to monitoring expansion, however, are the costs of installing new monitoring wells and monitoring equipment, and the inability to monitor on private, stakeholder property where the groundwater risk is high, and little is known. The logical next step must, therefore, be to expand monitoring to private domestic and small agricultural production wells. To do this effectively requires new monitoring systems that don’t present the risk of groundwater contamination, loss or damage to equipment in a pumping well, and that can provide research and management ready data. Simple acoustic sensors connected to a cloud-based system provide the means to incorporate accurate, real-time data from private, production wells without touching water, while enabling tracking and tagging of sensor readings to handle pumping influence, and providing secure, flexible access to data online. Online access enables well owners and local stakeholders to have their own secure, account where they can have control over data sharing, monitor well operation, and view groundwater trends and seasonality. Expanding monitoring to private wells, with the appropriate technology, supports new requirements for dense groundwater-level data, but additionally provides the opportunity for direct stakeholder engagement with data, new and broader understanding of shared resources, and a smoother path to consensus around management strategies, supporting implementation and advancing progress towards sustainability goals.

The Emerging Revolution in Groundwater Rights

Jesse J. Richardson Jr., J.D.

Tier IV Engines

Fred McAninch and Blake Fahl

Water Quality and Treatment

Activated Carbon, A Love Affair Spanning 15 Years

Scott Noland
Recent interest in “Carbon Based Injectates” has spawned many opinions on applications and limitations from a spectrum of sources including EPA, various regulators, and consultants. RPI Group has been injecting products based on activated carbon for over fifteen years and we’ve learned a lot.
RPI is in a unique position to talk about this technology and along the way we not only learned about activated carbon but also got an education on injections in general. Improving distribution continues to be a prime concern.
Fifteen years ago, there were no papers in the literature or books in the library describing how to calculate dosing or design an injection plan using activated carbon products for in situ remediation. It was a new application and all aspects of the technology had to be developed from scratch. Over time, RPI Group learned how the fundamental properties of activated carbon translated into performance in the field. Limitations of activated carbon became clear and the industry must be cautious how the technology is used. Absorption is an equilibrium process and sorbed compounds are not fixed. Desorption (rollover) is a fundamental problem that can create significant issues.
Highlights from a collection of projects representing failures and successes will be discussed to illustrate specific lessons learned. The main focus of this presentation is on activated carbon, its strengths and weaknesses; Its variety and diversity, and why it should play an ever-expanding role in remediation.
Results/Lessons Learned. The following list highlights specific features of activated carbon and how it should be used that will be discussed in detail.
1. Bioavailability of Adsorbed Compounds
2. It’s a Conductor – So What
3. Rollover – a Fundamental Problem for PFAS
4. All Carbon is not the same – Avoid Reactivated Carbon
5. Degradation Kinetics Trumps Adsorption Capacity
6. Injection Technique is Everything.

Citizen Suits are Possible Regarding Groundwater Contaminaiton

Steven Hoch, JD
Groundwater has not be the subject of federal law until recently. Various courts have determined that the Clean Water Act may be applicable to groundwater if there is a hydrological or substantial connection to Waters of the United States. This opens up those who have water rights, use groundwater, recharge groundwater etc. to liability under the Clean Water Act. With this comes the specter of citizen suits and the need to apply for, obtain and follow the dictates of permits issued under the National Pollution Discharge Elimination System. We will explore the parameters of the Clean Water Act, what it requires and entails, and the current position of various courts and the EPA. The goal will be to educate those in the groundwater industry of this potential sword of Damocles that could create endless litigation, complication and cost in relying on groundwater for the public good.

Groundwater Quality and Fracking: Current Understanding and Science Needs

Daniel Soeder
Over the past two decades, shale gas and tight oil development have opened up vast new reserves of fossil energy in North America. However, the drilling and hydraulic fracturing or “fracking” processes that are necessary for the production of these resources pose risks to groundwater.

A consensus view developed from two NGWA workshops held in 2014 and 2017 identified two primary risks to shallow aquifers from fracking: 1) stray gas associated with shale wells, and 2) groundwater contamination from surface spills of frack chemicals and produced fluids. Induced seismicity from the disposal of fracking wastewater down underground injection control (UIC) wells is an additional risk, but does not directly affect shallow groundwater. A lack of data on the true environmental risks of fracking is driving unsupported arguments on both sides of the issue.

Several field studies have provided evidence that gas or frack fluid do not migrate upward from hydraulic fractures into overlying aquifers. Groundwater and surface water contamination is typically caused by surface spills and leaks of frack chemicals and produced fluids, both at production sites and UIC wells. Stray gas in groundwater has been statistically linked to shale gas wellbore integrity problems, although the specific causes of wellbore integrity failures have not been identified.

Data gaps and science needs include a lack of pre-drilling baseline data, ongoing challenges gaining access to field sites and data from industry, uncertainties about the origins and migration pathways of stray gas, and the introduction of new frack chemicals with unknown degradation pathways and breakdown products. Non-standardized sampling and analytical methods make comparison of results from different studies challenging. A consensus recommendation from the workshops was to improve data-sharing, and develop standardized methodologies.

Groundwater Treatment for the Removal of Arsenic and Uranium

Peter Meyers
Ortega Oaks is a 25 acre parcel recreational vehicle (RV) campground located on Ortega Oaks Highway halfway between San Juan Capistrano and Lake Elsinore in Riverside County. The well water at this site has an Arsenic concentration of approximately 16 ug/L and Uranium of 39 pCi/L . Both contaminants exceed the federal drinking water MCL’s of Arsenic of 10 ug/L and Uranium of 15 pCi/L as well as California State limits.

In order to protect the campground’s residents’ health, a treatment system consisting of a selective media selective for both arsenic and uranium was installed in 2016 to remove Arsenic and Uranium to be below their respective MCLs.

This paper discusses how the system was conceived, built, certified to state standards, and installed. Results from the first two years of operation are discussed along with how the system was validated and accepted by the state. The first lot of spent media has been disposed as TENORM waste at the Clean Harbors disposal site in Buttonwillow, CA.

New Directions for Improvement of Groundwater Quality

Bruce Manchon, PG
Well installation and seal construction techniques that are widely accepted may not be working as designed. The importance of isolating the primary producing aquifer cannot be stated strongly enough - an effective seal above and below the aquifer needs to be established. Without a good seal, water quality may be impacted due to changes of the geochemistry of the aquifer from the mixing of waters from different units; the mixing of surface water and groundwater; or, the introduction of oxygen during the cycling of the irrigation season.

For any new well construction or well rehabilitation, the importance of understanding the complete hydrostratigraphy cannot be understated. Additional factors to consider that impact the groundwater quality from poor well construction include: inadequate seals or long screen intervals that cross-connect water bearing units of different water quality; or long screens intervals or breaches in the casing that result in water cascading and oxygenating the water column.

Case studies will be presented showing the long-term increasing trends of metal concentrations in a municipal water supply well due to cross-contamination between aquifers and how to correct those trends.

The well workover technique includes the incorporation of a thorough evaluation of well construction details, borehole geophysical logs, geochemistry of the aquifers penetrated, and historical well data. Key to this technique, is installing a sufficient volume of grout material without destroying the well which provides a competent seal and appropriate groundwater protection.

Even with the new well construction rules in place in Nebraska, Colorado and other states, or more important historical well construction practices (when the rules weren’t in place), our groundwater quality is susceptible to the same risks, today as yesterday. As a consultant or well driller - What Standard of Care do you apply to your practices – what is your environmental liability?

The Removal of Long & Short Chain Perfluoroalkyl Substances via Granular Activated Carbn Adsorption

Adam Redding
Per- and polyfluoroalkyl substances (PFASs) and used in many industrial and commercial applications including non-stick cookware, stain resistant fabrics, food packaging, as well as fire fighting foam products, such as those used in civilian and military aviation firefighting. They are problematic because of their persistence in the environment and their long half-life in humans. The two major PFASs of interest are perfluoro octanesulfonic acid (PFOS) and perfluoro octanoic acid (PFOA) due to their predominance in the above applications and associated USEPA Health Advisory Level of 70 ng/L (ppt). This paper cites test results relating to the removal of PFOA and PFOS via granular activated carbon (GAC) adsorption, as well as results exploring GAC efficacy for removal of other PFASs, specifically those with a shorter carbon chain length.

The USEPA recommends GAC adsorption as effective treatment technology for the removal of both PFOA and PFOS. This paper outlines the ability of domestic reagglomerated bituminous coal-based activated carbon to remove PFCs to non-detectable levels (< 2 ppt) and compares its performance to other GAC products in two groundwater well sites located in PA. The specific targeted PFCs are:

  • Perfluoro butanoic acid (PFBA)
  • Perfluoro butanesulfonic acid (PFBS)
  • Perfluoro hexanoic acid (PFHxA)
  • Perfluoro hexanesulfonic acid (PFHxS)
  • Perfluoro octanoic acid (PFOA)
  • Perfluoro octanesulfonic acid (PFOA)

The overall objective of this paper is to reinforce the EPA’s guidelines that granular activated carbon is one of the best available treatment technologies for the removal of PFCs like PFOA and PFOS, but also show that GAC can be highly effective for removal of shorter chain perfluoroalkyl substances.

Using Ultrasound to Minimize Mineral Depositions in Boreholes

Koen Kinsbergen
The use of low-powered ultrasound devices has proven to be efficient in the permanent removal of biofilm in pipelines. The efficiency of technology in stopping the bacterial induced processes which lead to Iron and Manganese deposits in boreholes can now be demonstrated. By eradicating the biofilm matrix, the bacterial propagation stopped. As a result of this cessation, the bacterial oxidation reactions leading to the deposits of Iron and Manganese also ended. It is now possible to avoid the buildup of sediments in borehole pumps and their exit lines while keeping the pumps running at their optimal performance, resulting in less maintenance and reduced power consumption.

Water Well Design by the Numbers

Marvin F. Glotfelty, RG and David Kill