Theme: 01. Remediation Technology Innovations

Topic Area: 01i. In Situ Chemical Oxidation: Optimized Design Approaches and Lessons Learned

Formatted Title:

Approaching ISCO Application Differently: Lessons Learned Over 15 Years of "Low-Volume, Chemical Oxidant Injection" Systems

Background/Objectives:

In addressing chlorinated ethene contamination, in situ chemical oxidation (ISCO), specifically using permanganates, has proven successful. However, certain site conditions complicate their use, such as distributing amendment in low permeability lithologies or fractured bedrock, application challenges due to preferential pathways, and site logistics. Additionally, matrix diffusion from fine grained units represents another challenge, resulting in late-remedy contaminant concentration spikes or rebound and prolonging treatment durations. Consequently, ISCO and/or permanganates may be excluded from remedy consideration or applied inefficiently in some cases.

Weaver Consultants Group, LLC (WCG), in partnership with a confidential Department of Defense contractor client, has developed a unique approach to ISCO application to address these challenges and meet site-specific objectives.,. WCG’s approach uses a proprietary automated, Low-Volume Chemical Oxidant Injection system, known as the “LVCOI” system. LVCOI systems establish and maintain highly oxidative and expanding treatment zones to drive matrix diffusion through sustained concentration gradients that reduce or mitigate late-remedy rebound. Tailored LVCOI system designs provide flexibility to overcome specific site challenges, adapt to changing site conditions resulting from treatment (dosing, amendment distribution, scalability), and promote sustainability through alternative energy sources and reduced carbon footprints.

Approach/Activities:

The presentation will outline WCG’s proprietary LVCOI technology and its operating principles aimed at driving matrix diffusion to eliminate or mitigate late-remedy rebound as well as address other site challenges. WCG will also demonstrate LVCOI system’s design flexibility, showcasing its adaptability and scalability to meet site-specific needs or objectives. Analytical data, trend analysis, and performance evaluations from multiple sites will be presented to showcase the LVCOI systems’ success at meeting site or program objectives and remediating contaminated sites. Furthermore, the presentation will incorporate lessons learned from various LVCOI iterations over a decade of design, implementation, and optimization strategies. These lessons will focus on increased amendment distribution, enhancing the geochemical environment, and leveraging natural aquifer characteristics.

Results/Lessons Learned:

Results from multiple LVCOI systems have verified the efficacy of LVCOI operating principles, resulting in reduced rebound and accelerated remedial timelines. These systems have successfully applied ISCO amendments in lithologically complex, low-permeability, and fractured bedrock geological environments. Data depicts the development of highly oxidative and expanding treatment zones, radii of influence (ROI) ranging from tens of feet to thousands of feet, reduced late-remedy rebound, and overall contaminant reduction. Lessons learned support maximizing permanganate remedies, such as enhanced performance monitoring, managing manganese dioxide production/accumulation, incorporating symbiotic technologies, and optimizing LVCOI systems. The LVCOI approach has facilitated the use of ISCO technology at logistically challenging sites, sites with fine grained units, and those with sustainability goals.

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Scott Andrews