Bannister Federal Complex

The Bannister Federal Complex is a 225-acre former federal facility that was transferred to a private developer for redevelopment. Historical operations had led to extensive contamination with chlorinated solvents, polychlorinated biphenyls (PCBs), hexavalent chromium, and petroleum hydrocarbons. The site has 47 Solid Waste Management Units (SWMUs) regulated under the Resource Conservation and Recovery Act (RCRA) via a Missouri Hazardous Waste Facility permit.

SSP&A was initially retained to determine the scope of remediation needed and the risks being assumed by the new property owner. These data were then used in the design and implementation of corrective measures under the Corrective Measure Study (CMS) process. To accomplish this, SSP&A set up and staffed a satellite office in Missouri. Tasks include:

• Risk Assessment: To assess risk, SSP&A performed a two-year Due Diligence Investigation, which included a review of historical documents, authoring regulatory/permit-required documents, and a remedial field investigation to confirm and document existing site conditions (~2,500 soil samples from 621 soil borings, 95 groundwater samples, and 9 soil vapor samples).
• Groundwater Flow Model: SSP&A developed a groundwater flow model to test scenarios for control of groundwater contamination during and after demolition of existing buildings.
• Remediation Measures: SSP&A evaluated remedial alternatives and developed corrective measures for soil, groundwater, and surface water, along with estimated costs for the environmental management tasks.
• Phased Extraction and Treatment Systems: SSP&A designed two phases of groundwater extraction systems and a new groundwater treatment system (GWTS) which could be operated under demolition and post- demolition conditions.
• Corrective Measures: SSP&A developed and implemented 10 Corrective Measures Implementation Plans, including installation of 4,000+ linear feet of surface barrier walls, 30 new groundwater extraction wells, installation of the GWTS, multiple phases of monitoring well installation, offsite disposal of >100,000 cubic yards of contaminated soil, and capping of SWMUs.
• Long-term Groundwater Monitoring Program: SSP&A developed a groundwater monitoring program for long-term monitoring of groundwater flow and hazardous constituents concentrations in order to evaluate the effectiveness of the corrective measures. Groundwater is sampled quarterly in compliance with the Missouri Hazardous Waste Management Facility (MHWMF) Permit. Groundwater samples are collected by SSP&A staff and undergo quality assurance/ quality control (QA/QC) reviews equivalent to a Stage II data validation. SSP&A uses quarterly sampling results to delineate the groundwater plume and evaluate the potential for off-site migration of the contamination.