Remedial Design/Remedial Action Implementation, Results, and Lessons Learned at the Orlando Former Gasification Plant Site, Operable Unit 1
Jim Langenbach, P.E., BCEE, Senior Principal Environmental Engineer, Geosyntec Consultants, Inc.
Historical operations of a manufactured gas plant (MGP) in Orlando, Florida from ~1887 to 1959 resulted in the release and on-Site disposal of chemical by-products, including coal tar. The historical releases resulted in soil and groundwater becoming impacted by metals, volatile organic compounds, polycyclic aromatic hydrocarbons, and Non-Aqueous Phase Liquids (NAPLs). Geosyntec prepared and implemented remedial actions for this Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Site. As a precursor to the full-scale remediation, an Interim Remedial Action was conducted and involved removal of approximately 7,000 tons of surface soils/debris at three affected parcels and associated right-of-way (ROW) areas followed by restoration activities. Parallel to the Interim Remedial Action, Geosyntec prepared a 60% Preliminary Design and a Final Design and associated engineering specifications and drawings for contractor procurement and selection at the 60% design milestone. The USEPA and FDEP approved the Final Design incorporating a combination of an in situ solidification/stabilization (ISS) low-permeability barrier wall to 60+ ft (over 1,000 ft in length) keyed into Hawthorn Group clays, excavation of a subsurface tar separator basin, ISS of two NAPL areas internal to the barrier wall, surface soils removal, and dissolved plume treatment outside the barrier wall via air sparging, soil vacuum extraction (SVE), and groundwater extraction and treatment. The air sparge and SVE design was based upon the results of a field pilot test conducted parallel to Final Design preparation. Remedial implementation in the the urban setting of downtown Orlando included local permitting, perimeter air monitoring from dedicated stations and other worker health and safety monitoring, maintenance of traffic, building demolition activities, and the excavation and disposal of nearly 10,000 tons of affected surface soils/separator basin soil and debris from five parcels and ROW areas. Site restoration included a combination of clean soil caps and impervious engineered caps to limit infiltration. Geosyntec coordinated with the contractor, Site owner and regulators to overcome multiple logistical challenges associated with road closures, historic roadway bricks and buried site structures, and construction activities adjacent to and with a railroad ROW. During ISS barrier wall and NAPL solidification/construction, QA/QC sampling was conducted to document that strength and permeability objectives were achieved. Groundwater remedy construction included the installation of 51 air sparge wells, 7 extraction wells, 8 injections wells, 15 vapor extraction wells, and nearly 30,000 ft of underground piping (5.6 miles) within an approximate 5.5-acre project area. Fourteen manifold cabinets were included for the zoned distribution/extraction of air and the injection/extraction wells were configured for flexible operations. The remediation equipment includes parallel SVE blowers with moisture separators and vapor off-gas treatment, a groundwater treatment train which includes an oil-water-separator, air stripper, bag filtration, and liquid granular activated carbon treatment and final treated effluent disposal flexibility to an infiltration gallery, injection wells, and/or sanitary sewer. A dedicated compressor system supplies the pneumatic groundwater pumps and the air sparging operations.
James Langenbach is a Senior Principal Environmental Engineer based in Florida with more than 20 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 group 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 30 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.