Real-Time Forensic Evaluation of PAHs During Sediment Investigation in an Urban Waterway
Sarah Meyer, Senior Managing Scientist, Ramboll
Co-Authors: Eric Hritsuk, Michael Bock and Lauren Brown, Ramboll and Patrick Kenny, WEC Energy Group
A streamlined method was established for delineating sediment affected by a former manufactured gas plant (MGP) that allowed the site to rapidly progress from field data collection to reporting and feasibility study. From 2017 to 2020, Ramboll conducted an investigation in the highly urbanized Chicago Sanitary and Ship Canal (CSSC), a part of the Chicago Area Waterway System (CAWS), and adjacent to a former MGP located in Chicago, Illinois. In 2017, an investigation was completed of a 1-mile (1.6 kilometer) reach of the CSSC immediately adjacent to the former MGP. MGP-affected sediment was observed at the upstream and downstream extents of the investigation area as elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) or observations of oil-wetted/coated sediment. Results of a forensic evaluation performed after field activities were completed indicated the presence of MGP-affected sediments at the lateral extents of the investigation area. Initial forensic analysis also indicated the presence of numerous non-MGP sources of PAHs in the sediment. Based on these results, additional investigation was required to delineate the nature and extent of MGP-affected sediment in the CSSC and additional forensic techniques were selected to distinguish MGP-affected sediment from sediment affected by other pollutant sources. Typically executed as a desktop exercise that lags behind field activities by weeks or months, Ramboll executed real-time forensic evaluations such that results could inform field decisions and the investigation could be completed during one mobilization. Within days of sample collection, automated techniques were used to quickly process lab data and update the forensic evaluation using the multivariate statistical methods of hierarchal cluster analysis and principal component analysis and comparing results to a library of known PAH sources. Ultimately, areas without MGP-affected sediment were identified upstream and downstream of the former MGP, indicating lateral delineation of MGP-affected sediment was complete.
Sarah Meyer is Senior Managing Scientist at Ramboll. She has 25 years of experience in environmental consulting and research throughout the Great Lakes Region and nationwide. Ms. Meyer has extensive experience in program and project management for large portfolio utility clients; and assessment and remediation work at sites that include contaminated sediments, manufactured gas plants (MGPs), coal combustion residuals (CCR), environmental emergency response, and time-critical removal actions. Currently, she develops strategy and manages a team of scientists and engineers for a portfolio of former MGP sites being managed using the USEPA Superfund Alternative Approach. Ms. Meyer assembles, leads and empowers teams to use best practices along with innovation to solve complex problems.