• Large-scale pilot tests confirm management of chlorinated VOC back diffusion from fractured bedrock aquifer
• Tests concluded degradation along biotic and abiotic reductive pathways
• Advanced sorbent technology extends treatment longevity to manage to manage long-term back diffusion

Fractured bedrock aquifers can be extremely heterogeneous which not only results in complex dissolved plume behavior, but can also hinder in situ remediation efforts that rely on an injection of amendments to promote microbial activity and abiotic degradation. However, due to the potentially high cost of a pump and treat remedy at a former industrial site in Arkansas, WSP determined that an in situ pilot test with advanced substrates was warranted.

At the Arkansas site, a 2016 pilot study was conducted using a multifunctional amendment formulation. REGENESIS® 3D-Microemulsion®, BDI Plus®, and CRS® were injected to remediate affected groundwater within a fractured sandstone bedrock aquifer impacted by chlorinated solvents. The contaminants at the site included trichloroethene (TCE), 1,1,1-trichloroethane (TCA), and degradation products. The plume on site underlies several developed properties and threatens a stream located approximately 1,500 feet from the source area. Results of the first pilot study yielded an 82% reduction within 9 months was measured approximately 80 feet from the application location.