Optimization of Remedial Strategies for CCR Site Corrective Action Through Advanced Geochemical Modeling

The power industry is actively designing and implementing corrective measures for Coal Combustion Residuals (CCR). In many cases, these measures include active remedies such as pump and treat, in-situ injection, or reactive barriers, all of which demand a thorough understanding of the underlying geochemical system. Depending on the geochemical characteristics of an aquifer, different chemical reagents can achieve varying degrees of success or even be detrimental to the remediation of the site. Advanced geochemical modeling is an invaluable tool for developing a remedy that is optimized to the site-specific geological, hydrological, and geochemical environment. In the case study presented here, geochemical modeling was used to calculate site-specific thermodynamic sorption constants, determine optimal barrier wall thickness, evaluate potential pore-clogging, and determine the maximum attenuation capacity of reactive media for arsenic remediation. This approach led to cost savings in both remedy design and implementation while providing additional evidence for successful site treatment in the long term. Overall, the use of geochemical modeling coupled with parameter optimization provides a tool to determine the most appropriate reagent dosing, evaluate long-term reagent efficacy, identify any potential collateral impacts or unintended outcomes, and avoid changes to aquifer characteristics that could negatively affect the remedy implementation.