Battelle provided a range of technical services to evaluate monitored natural attenuation as a potential remedial alternative at the Brooklawn site in Baton Rouge, Louisiana.  The RT3D reactive transport code was used to predict contaminant fate and transport as part of this evaluation.   The bioremediation team, following U.S. EPA guidelines, evaluated the lines of evidence that are required to support a decision to use monitored natural attenuation at the site.  Battelle provides natural attenuation analyses and other bioremediation services to clients around the country.

Conceptual model of lateral contaminant distribution.

Aerial view of the Brooklawn site.

The Brooklawn site is located north of the city of Baton Rouge, Louisiana and approximately one mile away from the Mississippi River.  The Brooklawn site is located at the interface between Pleistocene sedimentary deposits (clay material with occasional silt/sand lenses) and the recent alluvial sediments bordering the Mississippi River (typically interlayered silt, sand, and clay deposits).  Hydraulic gradients at the site vary significantly over time and are controlled by fluctuations in the Mississippi River stage.

It is estimated that approximately 160,000 tons of non-aqueous phase liquid (NAPL) contaminants were disposed at the Brooklawn site.  NPC Services, Inc. is currently applying hydraulic containment and source recovery at the site.  Based on the results of NPC Services Inc.'s efforts, with technical support from Battelle, monitored natural attenuation (MNA) has been selected as the preferred option for addressing the dissolved chlorinated solvent plume.   The MNA approach is replacing the previous pump-and-treat system at the site.

Battelle was contracted to evaluate lines of evidence for MNA and support the client in the use of the RT3D code to develop a numerical reactive transport model for the site.  Several tasks are required for this effort:

• MNA Screening Assessment:  Perform an initial screening assessment of natural attenuation potential at the site per U.S. EPA guidelines.
• Microcosm Tests:  Evaluate the degradation sequence and reaction rates for chlorinated ethane biodegradation at the site under natural attenuation conditions.
• Modeling Support:  Develop the necessary reaction routines and provide technical support in setting up and calibrating the site model.
• Groundwater Monitoring Guidance:  Provide input to monitoring plans with respect to meeting U.S. EPA guidelines for MNA.

The project was successfully completed in August, 2001.  Battelle provided technical support to NPC Services Inc. for submittal of a revised remediation approach at the site to the Environmental Protection Agency.  The assessment concluded that the dissolved-phase plume will stabilize and stop migrating before reaching the compliance location.  A long-term monitoring plan was proposed to meet the requirements for implementation of MNA as the selected remediation approach.

With Battelle's technical support, NPC Services Inc. has gained regulatory approval for implementing the revised remediation approach at the site.  A significant cost savings will be realized from this change.

Battelle's Chlorinated Solvent Bioremediation Design Service integrates geological, biological, and environmental data to design, simulate, and optimize bioremediation systems.  The service provides a design framework based on the RT3D reactive transport code to evaluate in situ bioremediation treatment.

 

For more information, contact:
Michael Truex Program Manager Field Hydrology and Chemistry Group	Battelle 902 Battelle Blvd., K6-96 Richland, WA 99352 USA	509-376-5461 509-372-1704 FAX mj.truex@pnl.gov