Fishbeck was selected by the performing respondents established in an Administrative Settlement Agreement and Order on Consent (Settlement Agreement) to design and implement a removal action strategy for a former manufacturing area of a Superfund Site in Missouri. Past operations resulted in impacts to the environment. The constituents of concern (COCs) included chlorinated volatile organic compounds (CVOCs) (primarily trichloroethene [TCE]) and petroleum hydrocarbons (PHCs) in seven discrete areas. The prescribed action was excavation of the most heavily impacted soil, treatment of residual CVOCs using soil vapor extraction (SVE), and biological degradation of residual PHCs with a bioventing system.
Fishbeck’s removal action design and implementation included excavation and onsite treatment of nearly 6,000 cubic yards of soil, installation of 10 horizontal extraction trenches and 16 vertical SVE wells, and installation of a low volume unsaturated zone bioventing (i.e., air sparging) system. TCE concentrations in excavated soils as high as 3,700,000 micrograms per kilogram (µg/kg) were effectively reduced to an average total volatile organic compound (VOC) concentration of 70 µg/kg, which was significantly less than the minimum treatment standard of 1,000 µg/kg total VOCs specified in the Settlement Agreement. The SVE systems included an innovative use of deep trenching technology to provide a larger surface area for vapor extraction in the clay-rich upper residuum (0 to 30 feet below ground surface) and increase the likelihood of intersecting permeable layers, thereby enhancing airflow through impacted soils. Vertical SVE wells were used in the deeper, more conductive soil zone. Field activities were performed from May 2015 to November 2021.
In 2023, Fishbeck prepared and submitted a final Removal Action Report describing all removal action activities conducted at the manufacturing area. The data presented in the report demonstrated that excavation and SVE had removed CVOC mass in source area soils and that bioventing had remediated PHCs to the extent practicable, thereby meeting (or exceeding) the requirements for the removal action set forth in the Settlement Agreement. In October 2024, USEPA approved the Removal Action Report, indicating their concurrence with this assessment.
Fishbeck worked closely with the performing respondents throughout implementation of this project, ensuring that the proper resources were available, project budgets and schedules were adhered to, site constraints and challenges were overcome, and a successful project completion was achieved.
