November 12, 2021

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Jim Langenbach and Rachel Klinger to Present on Site Remediation at International Symposium and Exhibition on the Redevelopment of Manufactured Gas Plant Sites

Jim Langenbach, P.E., BCEE and Rachel Klinger, P.E., BCEE (Florida) will present on site remediation at the International Symposium and Exhibition on the Redevelopment of Manufactured Gas Plant Sites (MGP 2021) at the Rosen Centre Hotel in Orlando, Florida on November 18–19, 2021. Geosyntec will also host an exhibit booth at the event.

Rachel Klinger is a Senior Principal Engineer based in Florida with more than 12 years of environmental consulting experience focused on providing groundwater, soil, and sediment assessments; remedial system technology evaluations; cost estimating and design; remedial system construction, operation, and optimization; and site closure strategy development.

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.

MGP 2021, which represents the eighth event in the Symposium series, will draw site owners, utility representatives, renowned and seasoned remediation professionals, environmental and development attorneys, banking and finance representatives, environmental regulators, operations and communications experts, and economic and brownfield redevelopment professionals together in one location to focus on very specific aspects of this industry.


Remedial Design/Remedial Action Implementation, Results, and Lessons Learned at the Orlando Former Gasification Plant Site, Operable Unit 1
Presenter: Jim Langenbach, Geosyntec
Time/Date: 8:30–10:00 a.m. EST on November 18, 2021
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 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.

Understanding Mass Flux: From MPE System to MNA
Presenter: Rachel Klinger, Geosyntec
Time/Date: 8:30–10:00 a.m. EST on November 19, 2021
To support the refinement of the conceptual site model (CSM) for remedial system design, Geosyntec deployed innovative passive sampling devices in sediment and surface water to evaluate potential mass flux from MGP impacted groundwater to surface water receptors. Geosyntec's comprehensive and integrated approach to understand the mass flux involved the use of three passive samplers, developed by SiREM and the University of Florida Contaminant Hydrology Laboratory (UF Lab). The passive samplers included polyethylene-based samplers (SP3™) developed by SiREM and sediment bed passive flux meters (SBPFM) and passive flux meters (PFM) developed by the UF Lab. Prior to sampler deployment, comprehensive Site reconnaissance activities were completed to assess sediment thickness, the presence and type of creek bed material, regions of groundwater upwelling through infrared sensor investigations and the vertical and horizontal extents of non-aqueous phase liquid (NAPL) impacts. The sampler deployment locations in sediment and surface water were conservatively chosen to represent areas where groundwater upwelling was most likely and mass flux would be highest. The results of the mass flux assessment indicate that while NAPL is present, MGP residuals are not discharging at concentrations exceeding Florida surface water cleanup standards. Not only did the work result in remedial costs savings but also demonstrated that passive remedial actions such as engineering and institutional controls would be an effective means of managing environmental risks. This presentation will discuss the importance of enhancing the CSM to support remedial decision making.

More Information

About the event: MGP 2021
For consultation regarding MGP sites, contact Jim Langenbach at This email address is being protected from spambots. You need JavaScript enabled to view it.
Learn more about Jim: Jim Langenbach – Geosyntec Profile
Learn more about Rachel: Rachel Klinger – Geosyntec Profile