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2021 to 2024 Research Contract
Ai-TS was awarded a large federally funded contract in 2021 and is currently conducting laboratory bench-scale experiments to evaluate the owner's patented in-situ groundwater treatment technology for site-specific contaminants. The SubflowRxTM is under consideration as a remedial alternative for contaminated groundwater beneath a federal facility.
A team of chemists, geologists, and engineers are working together on the multiyear contract focusing on two primary parts of the research:
Part 1: Identify candidate treatment media and conduct column tests to assess which media, or a combination of media, are best suited to reduce specific contaminant concentrations in a saline environment through any number of mechanisms, including, but not limited to: sorption, precipitation, sequestration/encapsulation, and transformation.
Part 2: Conduct a laboratory bench-scale study using a small-scale SubflowRx in an analog flow model that simulates site conditions. A miniature replaceable treatment cartridge (the patented CartridgeRxTM) will be filled with the selected media from Part 1 of the study. A key objective is to assess if the SubflowRx is capable of controlling groundwater contamination in a simulated saline hydrogeologic environment – to eliminate downgradient ecological risks that have been identified – without impacting the unique hydrodynamics of the remedial system.
VE Project 4-2-highlight.mp42022 Laboratory Experiments
The adjacent video shows one of many ongoing laboratory bench-scale experiments being conducted by Ai-TS using an Analog Flow Model (AFM) which houses a miniature-scale SubflowRx. Once steady-state flow conditions are established in the AFM, fluorescent dyes are used to document simulated groundwater flow conditions prior to the injection of contaminants of concern.
Once the objectives of the bench-scale research project are met, a field pilot test of the SubflowRx will likely be performed at the site where ecological risks have been identified. The client considers the SubflowRx ideal for the site because of its:
Small footprint
Minimal impact on nearby sensitive ecological environments (by the ability to drive modular components in the subsurface)
Ability to use customized media placed inside the CartridgeRx to treat targeted contaminants
Should other contaminants be identified during ongoing remedial investigations, different treatment media can be customized within a single CartridgeRx – or multiple cartridges can be installed in the patented PileGatesTM.
2023 and 2024 IR&D Projects
Ai-TS employees have recently undertaken two laboratory-based Internal Research and Development (IR&D) projects to test specific candidate media developed separately by Alexander Innovations, LLC (Ai) for effective use in the CartridgeRx. Two primary candidate media were developed under Ai-IR&D Project 3923 that were demonstrated to be effective in treating site-specific contaminants of concern (COCs) of interest to a client. A third candidate media was developed under Ai-IR&D Project 5124 which enhances the treatment afforded by the two primary candidate media.
Both IR&D projects have included numerous laboratory column experiments in the Ai-TS Hydrogeology Laboratory in which various candidate media in the columns are subjected to a constant inflow of COCs formulated to simulate actual site conditions. Column effluent samples are collected and analyzed for COCs by an independent chemistry laboratory. Special collaborative arrangements have been made for Ai-TS employees to work directly in the chemistry laboratory and prepare samples for analysis by inductively coupled plasma optical emission spectrometry (ICP-OES).
Analytical results were received from the chemistry laboratory the morning after each column experiment was performed so that Ai-TS could make decisions about the duration of a subsequent column experiment for the anticipated breakthrough of COCs. The timely analytical results were also helpful for Ai in adjusting the formulation of the candidate media and/or the use of other commercially available materials to enhance COC removal efficiency.
Two significant technical challenges were solved by these IR&D projects by developing:
Candidate media that met a specified chemical boundary condition (i.e., a sustained COC removal efficiency of at least 90 percent)
Candidate media of an optimal and consistent size that met a physical boundary condition (i.e., a specific permeability required for optimal flow to occur within the CartridgeRx such that COC contact time with the media is maximized for effective treatment without restricting the flow of contaminated groundwater)
2020 Research Grant
As part of an economic development grant, bench-scale laboratory experiments were conducted by Ai-TS in an AFM coupled with numerical groundwater modeling. The experiments and modeling demonstrated hydraulic proof-of-concept of the SubflowRx.
The results of the first phase were used to design and successfully install a full-scale remedial prototype system at an uncontaminated research site near Hillsborough, NC. The system includes:
112 linear feet of a vinyl sheet pile barrier wall installed in a trench excavated through residual soil and partially weathered rock to the bedrock surface
3 PileGates interlocked with the sheet piling
A CartridgeRx with permeable material in each PileGate
32 piezometers to monitor groundwater flow
The groundwater hydraulics of the SubflowRx will continue to be monitored by Ai-TS for years.
Installation of Prototype PileGate
PileGate PG-2 is lowered into position at the midpoint of the hydraulic barrier wall using the long arm of an excavator. The prototype of PG-2 includes a 12-inch diameter FRP pipe pile connected to vinyl sheet piling. The video shows PG-2 interlocking with existing sheet piling prior to gravel backfilling along the barrier wall at the research site.
VE Project 2.mp4VE Project 1-5.mp4Installation of Prototype CartridgeRx
A prototype CartridgeRx (CR-2) is lowered into PG-2 at the midpoint of the hydraulic barrier wall. The prototype contains a high permeability gravel (78M) and no treatment media since the research site is not contaminated. A black annular seal in the center of CR-2 is connected to a filler tube that extends to the ground surface for seal inflation.
Conducting Pumping Test of SubflowRx
Groundwater is pumped from PG-2 during a 5-hour test on September 5, 2020. A low-flow rate was maintained throughout this initial test while groundwater levels were measured in the three PileGates and network of 32 piezometers. The purpose of the test was to assess the hydraulic head differentials upgradient and downgradient of the barrier wall. The video shows groundwater measurements at PG-2 and PZ-21.
VE Project 1-2-highlight.mp4The NC Board for Licensing of Geologists approved the use of the results of the 2020 research project for development of an ongoing Hydrogeology/Remediation Short Course offered each year by Ai-TS. The short course is instructed by Joseph Alexander and includes a two-hour laboratory component demonstrating the AFM and numerical modeling results followed by a two-hour field trip to the research site where the prototype SubflowRx is installed. Four continuing education credit units are provided to professional geologists and engineers seeking credit units to renew their annual license and who participate in the short course: https://www.ncblg.org/resources/approved-continuing-ed-database .
Small-Scale Projects
Ai-TS has conducted numerous Phase I Environmental Site Assessments (ESAs) in support of due diligence efforts by clients. Properties included manufacturing and industrial facilities (brownfield sites).
Ai-TS completed a small-scale environmental project to evaluate, design, and install a long-term sediment and surface-water quality monitoring program to assess potential impacts on a pristine rural lake from an adjacent timber harvesting site.
Other Ai-TS projects have included the design and installation of unique subsurface drainage systems coupled with storm-water detention basins to prevent sediment and excessive surface-water flow from discharging into protected streams.
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