FRC 2025 Poster Presentations

2024 Posters

Alternative Solutions for Contaminant Remediation: An Evaluation of Two Horizontal Case Studies

Elliott Andelman, P.G., Environmental Project Manager, Directional Technologies, Inc.

Abstract:

Background/Objectives:    

Two case studies are presented where horizontal remediation wells (HRWs) were selected as the remedial solution to target subsurface contamination as an alternative to traditional vertical methods at sites in Florida.    Challenges presented in Case Study 1 involved access restrictions to groundwater contamination that resided beneath above ground storage tanks (ASTs), limited staging and setup locations for the drill rig, and 24/7 facility operations that could not be impeded during well installations. Vertical drilling techniques were not a feasible solution due to the surface-level access restrictions on site.     Challenges presented in Case Study 2 involved targeting subsurface contamination beneath a busy intersection and off-site adjacent properties with limited surficial access availability. Shutting down the gas station for the installation duration would significantly impact business revenue and was therefore not an option.  

Approach/Activities:

Twenty one (21) individual horizontal air sparge (HAS) wells were installed from four (4) discreet rig staging locations, which were strategically selected to avoid significant restoration costs and prevent disruptions to 24/7 on-site activities. Advanced drill-bit locating services were implemented to accurately install the wells beneath the ASTs and active roadways where standard walk-over locating services were not feasible. Wells were installed via the blind installation method, where an exit point is not required, due to site space constraints.     Eight (8) horizontal wells were installed to combat a petroleum release at a gas station bordered by a busy intersection and neighboring commercial and residential properties. Contamination had migrated slightly upgradient beneath the intersection and downgradient off-site onto adjacent properties. Vertical drill rigs could not be positioned above the upgradient contamination without shutting down the intersection. Down-gradient access had not been granted by the property owners to install vertical remediation wells. All 8 wells were installed via the entry-exit method, contrary to the installation method used in Case Study 1.     

Results/Lessons Learned: 

Horizontal remediation wells were able to access the target contaminated zones and perform the necessary remedial applications at the sites in both Case Study 1 and Case Study 2, despite the site-specific challenges presented at each site. By utilizing horizontal directional drilling techniques, there were no disruptions to business operations and no loss to client revenue as a result of installation operations. Through teamwork and collaboration with the environmental consultants, the horizontal well screen designs were optimized for each remedial application. Installation techniques were chosen based on site access restraints to install the wells into the target locations and ultimately reduce the remedial timeline of each project.   

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A Modern View and Approach to Measuring, Reporting, and Designing with Mass Flux Data

Brett Hicks, Central Region Manager, REGENESIS

Abstract:

Background:

The in situ remediation of contaminated aquifers continues to be one of the most cost and energy-efficient means of restoring and protecting natural water resources. To properly implement any in situ remedy, the extent and magnitude of contamination must be well understood as well as the geologic and hydrogeologic settings. Monitoring wells and traditional site characterization methods are effective at locating and tracking the extent of contaminants but may blur some of the most important details needed for effective treatment. Even other high resolution site characterization methods can often miss the areas that serve as contaminant transport zones. Underperformance or failure of many treatments can be attributed to a mismatch between amendment placement and key contaminant transport locations. The vertical extent of contaminant and groundwater flux are key data sets that better guide remedial efforts and help ensure long-term project success.      

Approach/Activities:

This presentation will cover the use of Flux Tracers to directly measure contaminant and groundwater flux. These new passive devices were developed to easily collect contaminant and groundwater flux data at discrete vertical intervals. These data allow site managers and remediation designers to identify the aquifer zones driving contaminant transport and plume formation. While the concept of flux measurement is not new, these devices improve upon existing methods by making device deployment and sampling significantly more user friendly. The flux measurement devices arrive on site fully assembled, ready to be unpacked and inserted into an existing monitoring well. After deployment, the measurement unit is removed from the well, repackaged, and returned intact for laboratory analysis - no field sample preparation is required. By bringing device handling and sampling into the laboratory, we achieve a higher level of process control and therefore data quality.    

Results/Lessons Learned:

The design of the devices will be introduced, and the data generated from project sites will be reviewed. Emphasis will be given to the improvements made to the design and implementation of remediation projects using the data collected from these devices. Available data collected using these devices will be used to show vertically delineated, flux-based contaminant and groundwater measurements hold tremendous promise in improving the design quality a  

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Sulfidated Zero Valent Iron Structure, Mechanisms of Operation and Performance 

Dr. John Freim, Ph.D., Director of Materials Science, Regenesis 

Abstract:

Zero valent iron (ZVI) is a powerful reductant that can accomplish the in-situ remediation of chlorinated hydrocarbons and other toxic groundwater contaminants.  Using sulfidated zero valent iron (SZVI) can help overcome some of the shortcomings of bare ZVI.  The key feature of SZVI is its core shell configuration with a thin surface layer of reduced iron sulfide with a zero valent iron interior.   It has been reported that for bare unsulfidated ZVI, hydrolysis consumes over 95% of the material.  Preventing hydrolysis is particularly important when using nanoscale or small microscale iron where using bare ZVI results generally results in premature material exhaustion and short reactive lifetimes.   In addition to extended persistence, reaction kinetics with chlorinated hydrocarbons is exceptionally rapid.  Scanning electron microscopy with electron backscatter analysis was used to verify the core-shell structure of a commercially available SZVI material.  We will then describe theories and mechanisms that explain the beneficial features of SZVI.  Notably, iron sulfide is relatively hydrophobic, and this is believed to favor reactions with contaminants instead of hydrolysis.  Additionally, iron sulfide is relatively conductive allowing for better electron transfer from the zero valent iron interior to the surface where the reactions occur.  The results of treatability studies with chlorinated ethenes are presented showing that SZVI increases reactivity with TCE by about 30 times compared to bare iron.   The results of a column study are also presented where a TCE solution continuously was passed through a sand column containing a representative in-situ dose of SZVI.   Reactivity was maintained for over four years with the near complete elimination of TCE and its daughter products.  The results of remediation programs using SZVI in combination with complimentary remediation amendments are described.   These show that SZVI accelerates bioremediation with fewer and shorter-lived daughter products.  SZVI can also accomplish in-situ destruction is permeable reactive barriers containing activated carbon products enhancing their performance.  

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Remediation of Contaminated Soils using Sustainable Soil Amendments

Dr. Fayaz Lakhwala, Ph.D., Key Accounts Manager Soil & Groundwater Remediation, Evonik Corporation

Abstract:

Agricultural, industrial, and military sites have been successfully remediated throughout the world using sustainably produced organic soil amendments over the past 25 years. Contaminants treated using this approach have included petroleum hydrocarbons, PAHs, phthalates, chlorinated phenols, chlorinated herbicides such as 2,4-D, and chlorinated pesticides including Lindane.    The soil amendments, known as Terramend® reagents, are manufactured using processed plant materials, a balanced blend of nutrients, and a food grade emulsifying agent.  This formulation promotes more rapid and complete destruction of the targeted contaminants and enables the attainment of industrial and even residential land use standards.  This approach to soil remediation provides a more economical and environmentally sustainable alternative to excavation, thermal treatment, or off-site soil disposal by landfilling.    Many large-scale projects using Terramend® reagents have been completed in Canada, the United States, and Europe.  Together, these projects have resulted in remediation of more than 1,000,000 tons of soil, sediment, and industrial process wastes.  Treatment has been conducted both in situ without excavation, on-site following soil excavation, and off-site at soil treatment centers.      The presentation will illustrate how Terramend® reagents improve soil microbial ecology by increasing the supply of bioavailable water and nutrients and reducing acute soil toxicity.  These changes lead to increased microbial growth and support more rapid contaminant destruction as compared to alternate bioremediation approaches.  Results from bench-scale testing and full-scale projects will be presented and discussed from the perspectives of performance and cost. Brief case studies will illustrate attainable removal efficiencies as well as recognized limitations to this type of soil remediation.    

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In Situ Injection of Modified Clay for PFAS Remediation: Field Demonstrations Examined

Derek Pizarro, CPG, Senior Geologist and Product Manager, AST Environmental, Inc.

Abstract:

Background/Objectives:

Use of common adsorbents for the remediation of per- and polyfluorinated substances (PFAS) in situ has generally been limited to liquid activated carbon (LAC) - also known as colloidal activated carbon (CAC), and biochar (BC), or conventional pump and treat systems. A significant issue with LAC/CAC/BC installations for remediation of contaminants is the mobility of the product after the energy of injection ceases. Most of these low-energy applications are not adequate to capture the total contaminant mass present due to limits in total effective sorption capacity and mobility of the product in the subsurface pore space. Further, conventional emplacement techniques of LAC/CAC/BC are ineffective for optimal distribution within certain overburden and regolith mediums.    Until recently, due to mesh size and chemical composition, practitioners believed that modified clay was not deployable in situ without the use of conventional soil mixing or civil construction techniques. However, overburden injection of an organically modified clay has been demonstrated using direct push technology (DPT) and high-solids slurry batching and injection equipment.      

Approach/Activities:

The modified clay selected was manufactured by applying an organic chemical modifier to bentonite clay parent material. The resultant product has high sorption kinetics, significant sorption capacity, can be effective across a wide range of PFAS concentrations, and, if necessary, is compatible for co-mixing with many other common site remediation reactants. In most cases, this combination functions without detrimental interaction or competitive adsorption for PFAS contaminants. These statements have been verified by independent university laboratory testing where the product was comparatively assessed with ion exchange resin (IX), GAC, and biochar. Additionally, competitive adsorption was tested with co-contaminants such as chlorinated volatile organic compounds (CVOCs) and petroleum hydrocarbons (PHCs). Relevant sorption and kinetics data will be discussed.    

Results/Lessons Learned:

Field installation of modified clay was conducted at sites in Kentucky, California, and Alberta (Canada) to prove the injectability of the technology in source (grid) and transmissive zone (PRB) settings. These demonstrations verified the injectability and distribution of the modified clay as effective in different geologies and site deployment usages. Various slurry designs were also tested in the Kentucky example, examining increasingly dense and higher solids mixes to mimic site situations where significant product mass would be matched to significant PFAS mass. Field distribution verification testing was a focus of the Alberta deployment, and co-mixing of modified clay and reactants will be reviewed in the California example.  Slurry designs will be discussed from bench scale evaluation to field deployment including lessons learned from varying the ratios of product and carrier fluid (water). This discussion includes the use and necessity of adaptable overburden remediation injection units (high energy/high flow trailer systems) - combined with specific downhole tooling and field installation protocols- to provide precise and proficient installation of modified clay injectate in a variety of unconsolidated and consolidated geologic settings to remediate PFAS.

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Mitigating LNAPL Migration into an Adjacent Surface Water Body Using a Regenerative PRB

Derek Pizarro, CPG, Senior Geologist and Product Manager, AST Environmental, Inc.

Abstract:

Background/Objectives:

At an active terminal site, petroleum sheening was observed on an adjacent tidally influenced waterway. It was determined to be caused by light non-aqueous phase liquid (LNAPL) seeping through soil and beneath a bulkhead (seawall). Initial responses, including mitigation of the source, placement of containment booms, and LNAPL recovery in sumps.     An extensive evaluation of potential remedial technologies was completed to complement these deployments. The process also had to consider the conceptual site model and the structural stability of the seawall (heavy equipment could not be utilized). A permeable reactive barrier (PRB) installed via direct push technology (DPT) was selected as the most appropriate remedial approach in two areas along the bulkhead. To optimize the performance of these PRBs, high-resolution site characterization (HRSC) was twinned with a Remedial Design Characterization (RDC) event (soil, groundwater, sump water) to adjust placement, depth of installation, and product design loadings of the two PRBs.      

Approach/Activities:

A slurry composed of activated carbon, electron acceptors (calcium sulfate, magnesium sulfate), nutrients (corn starch and yeast extract), and custom-selected petroleum-degrading microbes was installed via DPT injection. The PRBs are designed to mitigate LNAPL seepage into the river via a trap and treat approach, while the barrier is also designed to adsorb dissolved-phase petroleum hydrocarbons- all of which are degraded via microbiological processes while adsorbed to and within the activated carbon structure and pore space.    Due to the concentration of LNAPL in soil, the installation of the PRBs was broken into two injection events to allow for formational uptake of a significant slurry mixture loading- matched stoichiometrically to the impacts from the RDC design. Using two events prevented the possibility of sub-optimal product distribution, short-circuiting, and daylighting versus attempting the deployment in one injection event.       

Results/Lessons Learned:

Baseline data in performance monitoring locations were collected prior to barrier installation, and included LNAPL thickness, volatile organic compound (VOC), anion, dissolved gasses, and total volatile petroleum hydrocarbon (TVPH) concentrations. Post-installation monitoring data (groundwater, sump water, and the water body) was conducted one day, one week, one month, and quarterly following barrier construction to evaluate the reduction of LNAPL in-ground and cessation of LNAPL discharge to the water body.  Initial post-injection groundwater analytical data indicated a significant (1 to 2 orders of magnitude) decrease in VOC and TVPH concentrations. Microbial activity was monitored using secondary lines of evidence, specifically a continued increase in carbon dioxide and methane concentrations, and a decrease in sulfate concentrations- which were elevated by the slurry installation. Continued monitoring was used to determine the necessity and timing for supplemental injections- electron acceptors, nutrients, and microbes, if necessary. This data is also used to optimize the supplemental injection mix by PRB or specific PRB segment. A timeline of data from pre-installation to current day will be presented and discussed, including the timing of initial injections and augmentation injections to date. 

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Quantitative High-Resolution Site Characterization (qHRSC) and Lessons Learned

Derek Pizarro, CPG, Senior Geologist and Product Manager, AST Environmental, Inc.

Abstract:

Background/Objectives:

Limitations in funding or regulatory requirements often lead to soil and groundwater data gaps and an incomplete conceptual site model (CSM). An accurate CSM leads to better remedy selection, surgical application of the chosen remedy or remedies, shorter remedial timeframes, and lower overall remedial costs. One of the most common data gaps is limited speciated saturated soil analytical data and discrete assessment in underlying units. An integral approach to characterization and remediation is to obtain spatially and vertically dense soil analytical data and vertical profiling of groundwater; vertical groundwater profiling can effectively be twinned with high density soil sampling to determine contaminant mass distribution, gradients, and variability in aquifer properties due to geologic heterogeneity. These limitations also apply to transition zone and bedrock units but can be resolved with recent advances in procedures and methodologies.    

Approach/Activities:

Most overburden injection via direct-push technology (DPT) is not adequate to capture the total contaminant mass present nor is the equipment effective for installation within the geologic medium. Improvements to overburden injection methodologies will be highlight the use of flexible overburden remediation units (low pressure/low flow to high pressure/high flow) combined with unique downhole tooling and field installation protocols to allow expert installation of all commercially available injectates.    Additionally, subsurface conditions exist within the transition between overburden and competent bedrock lithologies that may prevent the use of traditional equipment or techniques to reach and isolate the targeted depth interval for assessment and treatment. These obstructions can be naturally occurring (hardpan/caliche, chert layers, dense fine-grained sediments, gravel, partially weathered rock, etc.) or anthropogenic (cut and fill, buried rubble like concrete, etc.). Development of the GeoTAP™ technique has provided both access for characterization and access to these intervals. It been used successfully on 50+ project sites across the country accessing depths as great as 180 feet below ground surface. This method characterizes these zones such that drilling is conducted like a bedrock application and injection is like overburden reactant/reagent installations.     Finally, a key to bedrock remediation is not to just treat the highly transmissive zones. A combination of custom packers for discrete sampling and injection (18” between inflation elements) and a unique bedrock injection unit (flow rates ranging from 50 to 250 gallons per minute and pressures up to 2,700 psi.) allows focused treatment using high energy access to the smaller aperture fracture networks which typically contain more contaminant mass than more transmissive features. Being able to isolate and treat these zones is a key component to success at difficult fractured rock sites.    

Results/Lessons Learned:

A comparative evolution of recent improvements to techniques and approaches to characterization and injection in overburden, transition zone/saprolite, and consolidated lithologies will be discussed. Site-specific case studies will illustrate the development of both quantified high-density data (CSMs) and focused in-situ remediation techniques. Lessons learned and relevant data will depict the benefits of high-density indiscriminate soil and groundwater sampling for quantitative lab analysis, then subsequent aggressive techniques to install the required in-situ treatment in targeted locations and loadings. 

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Applying Horizontal Remediation Well Technology To Improve Site Clean Up

Julie Sophis, Geologist, Directional Technologies, Inc.

Abstract:

Horizontal or directional drilling is often associated with the oil and gas industry or utility installations. However, for over three decades, Horizontal Directional Drilling (HDD) technology has been used to install Horizontal Remediation Wells (HRWs) in the environmental industry. HRWs can cost-effectively remediate large subsurface areas, even in active and complex industrial sites that are difficult or impossible to reach with traditional vertical wells or other in-situ approaches. Due to the long reach of directional drilling, horizontal wells can span entire plumes, avoiding surface infrastructure and redevelopment activities. This presentation will provide an overview of horizontal remediation systems, covering the basics of HDD technology and compatible remedial applications. It will include case studies showcasing the installation of HRWs at redevelopment sites, demonstrating the technology's ability to improve project time, cost, and safety.

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Remediation and Restoration of Challenging Soil Conditions by Comparing and Designing In-house Treatability Techniques 

Dr. Bhagyashree Vaidya, Ph.D., Senior Staff Scientist – Environmental Remediation Technology, Langan Engineering and Environmental Services, LLC

Co-Authors: Padmanabhan Krishnaswamy, P.E., Senior Staff Engineer and Dr. Amita Oka, Ph.D., Senior Project Manager – Remediation Technology, Langan Engineering and Environmental Services, LLC

Abstract:

Among the currently available treatment technologies for petroleum-impacted soils, In-Situ Stabilization (ISS), In-Situ Chemical Oxidation (ISCO), and Biosparging are some of the most effective techniques. Our in-house treatability techniques developed and designed to mitigate challenging soil conditions and restore the site to a natural/amended habitat for redevelopment have been demonstrated in the work presented here. We applied these three techniques to treat petroleum-impacted soil from a site located in the northeast. While ISS involves stabilizing in place hard-to-treat contaminants such as chlorinated solvents present in the Light Non-Aqueous Phase Liquid (LNAPL), ISCO involves the addition of chemical oxidants (hydrogen peroxide, permanganate, etc.) into the subsurface and targets petroleum hydrocarbons and chlorinated solvents. Alternatively, biosparging involves the injection of air/oxygen and nutrients into the saturated zone to enhance microbial activity and biodegrade the petroleum contaminants dissolved in the groundwater or adsorbed to the soil aggregates present under the water table. A comparative study of the three techniques showed which among the three techniques would provide an efficient and cost-effective solution to implement on a field scale to restore the site.

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