Jim Langenbach, P.E., BCEE

DNAPL Site Remediation - Examining the Life Cycle of a Solvent Site

Jim Langenbach, PE, BCEE, Senior Principal Environmental Engineer, Geosyntec Consultants

Historic releases of trichloroethene (TCE) from two discrete spill events resulted in the contamination of the surficial aquifer system at an industrial site in Cocoa, Florida (Site).  Distilled TCE was used at the site between 1964 to 1977 for the precision cleaning of new aerospace equipment prior to use in Apollo and other space missions. Detailed investigations in the late 1990’s through early 2000’s documented the presence of a largely depleted dense non-aqueous phase liquid (DNAPL) zone within thin clay layers underlying the site and associated dissolved plume extending approximately 1,200 feet downgradient.  Remedial activities were conducted over the course of 20+ years and included hydraulic containment with flushing, ISCO pilot testing, source zone bioremediation with recirculation, downgradient focused bioremediation, and natural attenuation monitoring, with a continuous focus on cost-effectiveness, optimization, and exit strategy considerations.  This presentation will present key conceptual site model (CSM) findings based on significant data collection, the remediation strategies developed and implemented for the site and how changes to the CSM over time were considered, regulatory challenges managed, current site status, and the potential path to closure 

James Langenbach is a Senior Principal Environmental Engineer based in Florida with more than 30 years of experience focused on assisting clients with environmental assessments; remediation design and treatment system optimization; environmental management systems; sustainable remediation designs; and regulatory compliance.

For decades, a wide range of industries have used chlorinated solvents as degreasing agents and for similar commercial applications. In many places throughout the world, these solvents have seeped into the ground near work sites, either through spills or as runoff, creating dense plumes of contaminants that can threaten aquifers and ecosystems. Jim is at the forefront of practitioners developing novel solutions to these issues in this field.

As a consultant, Jim is recognized for using innovative approaches in the planning and execution of projects that are grounded in practical applications of existing and emerging technologies. His clients include federal, state, municipal, and industrial sites throughout the Southeastern United States. He specializes in the management of multi-party PRP sites, and the characterization and remediation of complex manufactured gas plant (MGP), and chlorinated solvent sites with non-aqueous phase liquid (NAPL) source areas using the latest, proven assessment tools and remediation strategies to achieve exit-strategy focused remedial goals. Jim has served as Geosyntec's engineer-of-record on a number of key projects at NASA's Kennedy Space Center,  in addition to managing remedial actions at multi-party PRP sites such as the Orlando MGP Superfund Site. He also has served as Geosyntec's lead engineer on projects in Florida's Dry-Cleaning Solvent Cleanup and Hazardous Waste Program, during which he has completed assessments or remedial designs for more than 50 solvent, metal, and petroleum-impacted sites.

To advance the state of the practice, Jim's work emphasizes sustainable remediation approaches to the design or optimization of soil and groundwater treatment systems. Examples include his efforts to transition sites from energy-intensive, mechanical treatment systems to passive, in situ biological treatment and flux control approaches. He also designed and created a solar-powered groundwater recirculation system at Kennedy Space Center for the enhanced in situ treatment of a chlorinated solvent plume.