Formatted Title
Exploring the Influence of Soil Characteristics on Oxidant Demand and ISCO Design Parameters: An Evaluation of 80 Bench-Scale Studies
Background/Objectives
Successful in situ chemical oxidation (ISCO) involves chemical reactions between an applied chemical oxidant and an organic contaminant in the subsurface. The soil properties at a site, such as natural oxidant demand, minerology, and pH buffering, can influence ISCO effectiveness. Bench-scale tests, conducted at only a fraction of ISCO sites, determine treatability, potential failure pathways, and identify possible design parameters. Bench-scale treatability tests typically report total oxidant demand, oxidant reaction rates, and base buffering capacity to aid ISCO design. Where treatability data are not available remediation engineers estimate these values, determining design parameters loose estimates or extrapolations from treatability data on sites that may have some similarity. Few studies have attempted to relate oxidant performance and demand to soil characteristics.
Approach/Activities
The objective of this assessment was to use a set of bench-scale test data to bridge the gap in understanding how treatability test data vary across a range of site characteristics. The initial phase of the project involved compiling a database with data from bench-scale tests conducted at over 80 different sites. The database included data such as soil type, total organic carbon, metals, pH, total oxidant demand, base buffer capacity, and oxidant half-life. The second phase of the project consisted of interrogating the dataset to uncover relationships between soil characteristics and ISCO design parameters, determining which characteristics may be important indicators when undertaking design of ISCO treatments.
Results/Lessons Learned
The evaluation outlined in this abstract is currently underway in the Fall of 2023. The forthcoming presentation will highlight key findings, including recommendations for ISCO practitioners on remedial design across different soil types (sand, silt, clay, and fill). It will identify scenarios based on site characteristics, clarifying when conducting bench-scale tests is critical to the design and when generally applicable approaches (i.e., rules of thumb) may prove appropriate.