Emerging Contaminants Summit

Spring 2020

griffithsDaniel R. Griffiths
Project Manager and Technical Director
Parsons

Mr. Griffiths brings both a strong classical geological science education and extensive experience to a wide variety of projects, focusing on streamlined site delineation and innovative remedy design and implementation. He has been designing and implementing investigation plans at industrial and Department of Defense sites for approximately 22 years, specializing in complex high priority sites impacted with chlorinated solvents, organometals, metals, explosive constituents, and emerging contaminants like 1,4-dioxane and fluorinated compounds. Mr. Griffiths has worked extensively in all USEPA regions with particular emphasis on Regions 2, 3, 6, 9, and 10. His projects involve all aspects of CERCLA and RCRA including site characterization, remedy selection, remedy implementation, regulatory negotiation, and site closure. His primary areas of expertise include rapid site characterization using real-time data collection methods, MNA evaluations, design and implementation of in-situ remedial applications, and project management. He is a contributing author on guidance documents for in-situ remediation prepared by Parsons for the Air Force and ESTCP. Mr. Griffiths is also the Parsons Industrial Subject Matter Director for remedy design and a Parsons Federal technical director for investigation, remedy selection, design, and implementation. Mr. Griffiths has a B.S. and M.S. in Geological Sciences.

 
POSTER PRESENTATION

Full-Scale Treatment of a 1,2-DCA Plume Under Developed Properties With Enhanced Bioremediation

A former industrial site in Texas was impacted with 1,2-Dichloroethane (1,2-DCA) through historic waste disposal practices of the former site owners. Site soils and shallow groundwater within the source area were remediated through excavation, backfilling, and the installation of a property line hydraulic containment system. Subsequent groundwater investigations determined that a 4,000 foot long 1,2-DCA plume extends off-site from the former source area and runs under developed and undeveloped areas. A second hydraulic containment system was installed approximately 2,500 feet downgradient of the former source area in 2006 to reduce contaminant mass flux and to stop further plume migration. Both hydraulic containment systems continue to operate. A site-wide groundwater contaminant fate and transport model was constructed and monitored natural attenuation (MNA) evaluations were conducted to assess the site and predict remedial timeframes for the dilute plume. It was established through this process that site groundwater geochemical conditions are naturally aerobic and moderately acidic (pH 5.5). These conditions are not conducive to biologically mediated anaerobic destruction of site contaminants and thus, MNA remedial timeframes were predicted to be unacceptably long.

In 2007 a remedial technology review was conducted to identify technologies to treat the 1,2-DCA plume more rapidly than the existing pump and treat systems.  Enhanced bioremediation (EAB), pH stabilization, and bioaugmentation technologies were selected for field testing to determine if biologically mediated anaerobic contaminant destruction could be effectively employed.  An EAB pilot study was implemented, monitored for approximately 20 months, and achieved 70% to 99.9% reduction in 1,2-DCA concentration within the pilot footprint without the accumulation of undesirable intermediate products or the generation of negative secondary water quality impacts.

A full-scale EAB application with pH adjustment and bioaugmentation was designed and is currently being implemented based on the success of the pilot study. The full-scale application consists of ten permeable reactive barriers (PRBs). The PRBs are spaced 2 years of groundwater travel time apart to ensure that the intervening area would be affected by the injected substrates before the substrates reach depletion. The full-scale application was organized into five phases to be installed over 5 years.  The final phase of installation was completed in 2016. Now, in 2017, the first two phases of implementation that were installed in 2010 are reaching depletion and are scheduled to be refreshed with additional organic substrate and pH buffer to extend the active lifespan of these applications. An analysis of substrate depletion rates and effects; application longevity; and pilot study and full-scale system performance data will be presented.

Program Agenda  Scientific Advisory Board  Keynotes and Session Chairs  Platform Presenters  Poster Presenters