Objective: The Bayou Bonfouca Superfund Site (Louisiana Department of Environmental Quality [LDEQ] Agency Interest No. 4716) was a creosote plant (late 1800s through 1970) that is currently in the remedy phase of the Superfund process. The object of the investigation is to evaluate the current extent of the non-aqueous phase liquid (NAPL) groundwater plume and current constituent of concern concentrations in soil. In addition, Leaaf Environmental, LLC (Leaaf) was tasked to repair and replace multiple recovery and monitoring wells.
Description of Work: Under contract to LDEQ, Leaaf researched site history and worked in cooperation with the LDEQ, Environmental Protection Agency (EPA) Region 6, and the on-site treatment system Operations and Maintenance (O&M) contractor to conduct multiple site assessments, a Risk Evaluation/Corrective Action Program (RECAP Evaluation), and recovery well replacements. As part of these activities, Leaaf prepared Site Investigation Work Plans, Quality Assurance Project Plans (QAPPs), Technical Sampling and Analysis Plans (SAPs), and site-specific Health and Safety Plans (HASPs) in accordance with RECAP guidance.
The Site Investigation Work Plans were reviewed and approved by LDEQ, with input from EPA Region 6, and the on-site treatment system O&M contractor.
In 2018, Leaaf completed two Site Investigations designed to evaluate the current extent of the subsurface NAPL and current soil and groundwater constituents of concern (COC) concentrations used in creosoting processes. The project included locating the NAPL plume using TarGOST (Tar-specific Green Optical Screening Tool), a downhole-borehole NAPL screening technology, and collecting soil samples to confirm the TarGOST findings and determine current COC soil concentrations. The NAPL plume extent and soil and groundwater Samples were also collected near residences to facilitate enclosed space risk evaluation. COCs were documented in a RECAP Evaluation dated June 2019. In addition, borings were installed through the on-site ash landfill cap to sample and analyze ash characteristics for potential reuse options of the ash, and to evaluate the NAPL plum beneath the landfill.
In March 2020, Leaaf conducted a Limited Sediment Site Investigation to evaluate the concentrations of sediment COCs within Bayou Bonfouca. The data generated were evaluated with respect to the PAH standards defined in the 1987 Record of Decision and further evaluated by LDEQ and the Louisiana Department of Health with respect to human health risks. In September 2020, Leaaf replaced six recovery wells along with their submersible pumps and associated equipment.