Since 1986, several phases of investigation have been completed at the site, which identified negative impacts to soil and groundwater in the former hazardous waste handling areas. Constituents of concern (COCs) consisted of pesticides, chlorinated and petroleum volatile organic compounds (VOCs), and semi-volatile organic compounds (SVOCs). By 1996, initial soil and groundwater remediation began at the Site which included groundwater pump-and-treat, soil vapor extraction (SVE), soil excavation and disposal, and surface pavement capping. In 2018, a corrective measures study was conducted by Shannon and Wilson to compare possible remediation alternatives. It was found that in-situ chemical injection of Bioavailable Absorbent Media (BAM™) was successful in reducing the concentration of some constituents of concern in soil and groundwater at the site. 

In-situ chemical injections of BAM™ were completed for both soil and groundwater from October to November 2021. Soil and water samples were taken pre-and post-injection to monitor the success of the in-situ treatment. Results were inconclusive for soil remediation, some pre-and post-injection sample pairs showed decreases in COCs while others showed an increase or negligible change. Results for groundwater indicated that in-situ treatment was effective in decreasing VOCs in the groundwater. However, some pesticides, COCs, particularly VOCs, spiked after injection, then decreased slightly, but have remained above pre-inject concentrations as of October 2023. After the pilot study, Shannon and Wilson recommended that no further in-situ treatment occur as it would be cost prohibitive, and a risk-based approach would be the best model for obtaining regulatory closure of this site.

Project Highlights

• Shannon and Wilson conducted a corrective measures study to compare effective remediation alternatives for site-specific conditions.
• In-situ remediation technology via BAM injection was validated and a pilot test was completed for the treatment of the COCs. Based on inconclusive results, Shannon and Wilson adapted the plan and recommended a risk-based route to seek closure of the site and save costs.