From October 8 through 10, 2019, HGL participated in the 20th annual Business Opportunities and Technical Conference (BOTC) hosted by the Energy Technology and Environmental Business Association (ETEBA). ETEBA is a non-profit trade association representing approximately 170 small, large, and mid-sized companies and affiliate members that provide environmental, technology, energy, engineering, construction and related services to government and commercial clients. The conference was held in Knoxville, TN. HGL participated as an exhibitor at the conference, which drew over 500 attendees.
Tad Fox, P.G, HGL’s Director of Applied Modeling, presented HGL’s recently completed project involving groundwater (GW) modeling, remedial alternatives evaluation, and optimal design to address contamination beneath the DOE Pantex Plant in Texas. Pantex is the nation’s primary facility for assembling/disassembling nuclear weapons; the Plant also dismantles retired weapons and has been selected as the High Explosives Center of Excellence. Past industrial practices released materials such as RDX to the environment. An extensively monitored RDX plume in perched GW emanates southeast from release areas and has migrated off site. The impacted perched GW occurs within a thin zone of saturation 250 to 300 feet below ground surface and above the regional sole-source Ogallala Aquifer.
To design a remedial approach to contain off-site plume migration, HGL updated the existing conceptual and numerical models by (1) updating the extent of the perched water table, (2) conducting an extensive review of lithologic and geophysical data to define the top elevations of the semiconfining unit that constitutes the bottom of the numerical model, (3) expanding the areal extent of the model domain, (4) incorporating operation of two pump-and-treat systems with 74 extraction wells and 4 injection wells, and (5) employing both parameter estimation and data assimilation techniques to calibrate the model with over 7,000 observed GW levels and RDX concentrations measured between 2008-2019. The model was combined with HGL’s Physics-Based Management Optimization (PBMOTM) tool to evaluate potential RDX plume treatment options. On a Cloud computing platform, over 3,000 different remedy configurations were evaluated to determine the best remedy and design configuration. The capabilities of PBMOTM were expanded to assess in situ bioremediation (ISB) and to allow DOE to efficiently evaluate treatment options, well configurations, and associated budgetary considerations. Mr. Fox’s presentation provided an overview of the project and results.