Webinar | Residual NAPL And PAH Remediation

Join us on March 11, 2026 for a technical webinar regarding Residual NAPL And PAH Remediation: The Critical Role of Pre-Design Investigations, Treatability Testing, and Pilot Testing

Background/Objectives

Pre-design investigations (PDIs), bench-scale treatability testing, and pilot testing are critical for reducing uncertainty prior to remedial design. At a former creosoting facility Superfund site, in situ chemical oxidation (ISCO) was identified as the primary selected remedy. The objective of the presented work was to refine the conceptual site model (CSM) and evaluate cost-effective, feasible solutions through pre-design investigation and treatability testing to inform future pilot testing and full-scale design.

Approach/Activities

The 2025 PDI integrated TarGOST® laser-induced fluorescence, hydraulic profiling, soil borings, and groundwater sampling to characterize non-aqueous phase liquid, soil, and groundwater impacts at the site. Bench-scale treatability testing was used to evaluate persulfate-based ISCO within two distinct lithologies, silty clays and weathered limestone, to assess oxidant demand, treatment effectiveness, and zone-specific delivery feasibility.

Results/Lessons Learned

The PDI results refined the CSM, identifying more significant impacts in a weathered carbonate bedrock than previously understood. Treatability testing of ISCO demonstrated substantial reductions in polycyclic aromatic hydrocarbons (PAHs) in mixed silty clays, whereas limited PAH destruction and a high natural persulfate oxidant demand were measured in weathered limestone. A second testing phase is evaluating enhanced anaerobic bioremediation for the limestone. The second phase was informed by a successful application of sulfate at a different Superfund site treating PAHs. These findings highlight that PDI and bench-scale testing can prevent high-cost errors, leading to data-driven
remediation designs.

Presenters

Claire Harris, PG, Claire is a Senior Hydrogeologist with more than seven years of experience supporting site characterization and risk-based remediation.

Glenn Ulrich, PhD, Glenn is a technical director specializing in contaminant fate and transport, the sustainable remediation of contaminants and methane, and technology development.

To Join The Webinar

Join on your computer, mobile app or room device: Click here to join the meeting.

Phone Conference ID: 279 843 247 079 51
Passcode: st7N4sW7

Please visit the Parsons YouTube channel where video recordings of our previous
technical webinars are available for viewing.