2018 Groundwater Week: Alphabetical Content Listing
John Fowler, CSP, CMSP
Jason Polk, Ph.D., James Shelley and Rachel Kaiser
James Cannia, BSc, Jared Abraham, M.Sc. and Ted Asch, Ph.D.
A Five-Year Estimation of Wasted Potable Landscape Irrigation Water, Orange Crest-Mission Grove Area (OCMGA), Riverside CA
Thomas Deane, CHg, PG, RG
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
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.
Matt Bromley, M.S.
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
John Horst, PE, Nick Welty, PG and Allison Yanites
Bruce Manchon, PG and John Sciacca, PG
William Alley, Ph.D. and Rosemarie Alley
Design Verification Program - Lessons Learned from Pre-Application Assessments at In Situ Remediation Sites
Craig Sandefur, Rick Cramer, PG and Chris Lee
Wes McCall, PG
Bruce Manchon, PG and John Sciacca, PG
Don’t Forget to Disinfect…Developing a Strategy for Micrbiological Contamination in Private Water Systems.
W. Richard Laton, Ph.D., PG, Steve Sliver, Rick Hutchings, Edd Schofield and Nicklaus Welty
How the PFAS regulations got to where they are and what you can legally do to recover costs for damages
Richard Head, JD
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
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.
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.
Norman Carlson, PG
John Jansen, Ph.D., PG
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.
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.
Reinhard A. Klaus, Hydrogeologist
Daniel O'Rourke, PG
Rodney Sheets, William L. Cunningham, Charles W. Schalk, Candice Hopkins and Daryll Pope
Lauren Schapker and Margaret Martens
Application of 3D Visualization Modeling to Improve Conceptual Site Model Development and Groundwater Remediation
Richard Boone, CPG, CHMM
Development of a Revised Hydrogeologic Conceptual Model of the Indian Wells Valley Groundwater Basin
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
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
Christian D. Langevin, Ph.D.
Michael Cardiff, Ph.D.
Benefits and Limitations of Using Down Well, Real-time, Telemetric Water Quality Meters to Monitor Water Quality
Brian Symons, PE
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.
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.
- Provides a continuous, real-time record of groundwater conditions using accurate water quality parameters.
- Detect short-term events (i.e. minutes to several days) that can be missed during monthly or quarterly manual sampling events.
- Monitor water level, temperature, total dissolved solids, oxygen-reduction potential, dissolved oxygen, turbidity, pH, nitrate, ammonia, and chloride, downhole.
- Location and/or configuration of the monitoring point may limit the Tube 300R telemetry system’s ability to transmit real-time data.
- The total set of parameters is limited.
- 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.
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.
Ramsey Ferguson, PG
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
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.
Jay Piper, CEM
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.
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.
Joseph Fillingham, Ph.D.
The Effect of Close-Proximity Blasting on Groundwater Quality and Impacts on Communal Drinking Water Supply Systems
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.
Kevin Finneran, Ph.D.
Kevin Finneran, Ph.D.
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.
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
- 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.
Jason Downey, PE
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
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
Daniel P. Leigh, PG, CHG
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.
David Alden, PE
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.
Gary Birk, PE
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.
Jeffrey Holden, PE, LSP, LEP
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
Jeff Fitzgibbons, PG
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.
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
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.
A Comparison of Thermal Imaging and In-Situ Thermistor/Tensionmeter Data to Characterize Groundwater Seepage in a Fen
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.
Joe C. Yelderman Jr., PhD, PG
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.
Stewart Krause, Todd K. Tannehill and Jeff Blinn
Riva Daniel and Larry Oxenham
Matthew Wirth, BA
Hillol Guha, Ph.D., P.G., P.E.
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.
Mary Beth Koester, CVA
Environmental Isotopes in Time Series Resolve Issues of Imported Water Recharge in Basin Fill Aquifer
Barry Hibbs, Ph.D.
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.
Mark C. Lucas
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).
Roger Renner, Gary Shawver and Fred Rothauge
Brent Ardit, CPA and Joe Popp
Roger E. Renner, MGWC, NGWAF
Nicholas Kingsbury, President
Yong Sang Kim, PhD
Development of a Coupled Groundwater-Surface Water Model for Assessing the Impacts of Groundwater Pumping on Streamflow in the Middle Rio Grande Basin
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
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.
Strontium Isotope and Major Ion Geochemistry of Yalahau Fracture Zone Waters, Yucatán Peninsula, Mexico
Advancements to the EZVI Technology: Optimization of Biotic and Abiotic Processes and Improved Implementability
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.
David Walsh, Ph.D.
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
Fate of Emerging Contaminants During Infiltration of Untreated Wastewater in Mezquital Valley, Mexico
Luis E. Lesser, Ph.D.
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.
John Jenson, PhD
Management of Spent PFAS Adsorption Materials and Concentrates in Australia – Commercially Viable Solutions
Richard Carran, BSc, BBS, MSc
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.
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.
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.
Robert A. Schincariol, Ph.D., P.Eng., P.Geo.
Keywords: permafrost degradation, peat plateau, heat and water movement, ecohydrology
Role of Geological Heterogeneity in Poroelastic Deformation of Geologic Medium due to Groundwater Extraction
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.
Thermal Release Of Arsenic, Metals And Organic Compounds From Aquifer Sediments During In Situ Bitumen Extraction
Michael Moncur, PhD
Fred Rothauge, David Kaminski and Jeffrey Holden, PE, LSP, LEP
Steven D. Wilson
Don Cleveland, Steve Smith, Linda Colasurdo, Courtnee Stevenson and Bonnie North
Nikola Milivojevic, Ph.D.
Greg Beach, David Henrich, CWD/PI, CVCLD and Randy Carnes
Central Coast Blue: Creating a Sustainable Groundwater Supply and Combating the Threat of Seawater Intrusion
Michael Cruikshank, PG, CHG
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.
Leslie Dumas, PE
Timothy K. Parker, PG, CEG, CHG
Using Private Wells to Cost-Effectively Complement and Extend Groundwater-Level Monitoring Networks, Build Consensus and Facilitate Sustainable Management
Marian Singer, Co-founder & CEO
Jesse J. Richardson Jr., J.D.
John Fowler, CSP, CMSP
Fred McAninch and Blake Fahl
Daniel T. Meyer, CPA, MGWC, CVCLD
Thom Hanna, PG
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.
Steven Hoch, JD
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.
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.
Bruce Manchon, PG
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 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.