Working with PNNL on RT3D Applications

The RT3D developers and subject matter experts are staff in the Earth Systems Science Division at PNNL.

What We Do

Staff at PNNL have been developing and applying in situ remediation technologies and reactive transport software since the early 1990s. They have demonstrated strong capabilities in accelerated, in situ bioremediation (ISB) design and evaluation of monitored natural attenuation (MNA) in numerous projects for federal government agencies and private clients. The focus for the RT3D applications has been on treatment of groundwater contaminated with chlorinated solvents (e.g., TCE, carbon tetrachloride), but staff at PNNL have broad experience in development and application of many kinds of remediation technologies for both vadose zone and groundwater and for a range of organic, inorganic, and radionuclide contaminants.

• Customized Reaction Modules for RT3D – PNNL can efficiently develop customized reaction expressions within the RT3D reaction module framework to describe reactions at the level of detail needed for specific sites. For instance, coupled reactions for substrate use and subsequent dechlorination can be used to describe reductive dechlorination induced by lactate amendment or methanotrophic cometabolic dechlorination. Standard first-order representation of dechlorination for evaluation of natural attenuation can be improved to include non-sequential dechlorination pathways, inhibition terms, and electron acceptor dependencies for the reactions. Customized reaction modules provide a technical basis for reactive transport simulations that supports better designs for accelerated ISB and better defensibility with regulatory authorities for evaluations of MNA. PNNL has a variety of technical resources and can develop custom reaction modules for RT3D for applications other than chlorinated solvent bioremediation. For instance, descriptions of biological or chemical (e.g., oxidation) reactions for other organic contaminants, inorganic, or radionuclide contaminants can be included in custom reaction modules.
• Customizations of RT3D – In some cases, modifying the RT3D code may help conducting simulations for a site. For example, in one project, PNNL modified RT3D to accommodate cyclic flow conditions at a model boundary to represent seasonal variations in river stage. Instead of entering boundary conditions for 120 time points to describe this variation over the 30-year simulation, only four time points were input. Additional features can also be added to RT3D. An example is the ability to calculate injection well concentrations during recirculation between an extraction and injection well pair.
• Laboratory Microcosms/Column Studies – PNNL has extensive experience evaluating a variety of microbial metabolisms for reductive and cometabolic dechlorination through use of laboratory microcosms studies. PNNL has also conducted numerous experiments with soil columns/sandboxes to investigate the science behind non-aqueous phase, inorganic, and organic contaminant transport and remediation. PNNL structures these studies within a context of reactive transport analysis to specifically obtain the information important to design an active remediation system or evaluate natural attenuation.
• Accelerated ISB Design – PNNL has significant experience in designing accelerated, in situ, bioremediation systems. PNNL personnel have performed all system design aspects, including well network design, nutrient amendment strategy, equipment specification, system installation, and system operation.
• Natural Attenuation Evaluation – PNNL provides technical support for evaluation of natural attenuation and development of long-term monitoring plans associated with implementation of MNA. For sites requiring significant fate and transport analysis, PNNL can provide technical support for RT3D-based modelling. PNNL also has significant resources for addressing site-specific technical issues such as including the evaluation of DNAPL source areas (e.g., multi-phase transport assessment and estimates of source flux) with the evaluation of MNA for the dispersed plume. MNA evaluations require a thorough description of relevant attenuation mechanisms and development of lines of evidence for how these attenuation mechanisms are occurring at the site. PNNL can provide the technical information needed for these descriptions and serve as a respected technical expert when communicating these lines of evidence to regulatory authorities.
• Remediation Alternative Evaluation – PNNL can efficiently evaluate the viability of accelerated ISB, natural attenuation, and other remediation technology options, applying RT3D-based reactive transport simulations where appropriate. PNNL has performed this type of remediation alternative evaluation for sites at Hanford, Naval Base Ventura County, Joint Base Lewis McChord, Idaho National Laboratory, and elsewhere. Staff at PNNL have expertise spanning a gamut of bioremediation, chemical oxidation/reduction, sorptive, and thermal remediation technologies for a full assessment of potential remediation alternatives.

The Earth Systems Science Division at PNNL hosts an extremely broad range of expertise in all environmental aspects (geology, hydrology, ecology, risk assessment, environmental biomarkers, and more). This expertise and experience can be used to provide a quality solution that addresses the problem at hand.

Who We Are–RT3D Development Leadership

The RT3D development team operates within the collaborative context of a world-class national laboratory and a comprehensive research university. Key personnel for RT3D development include the following:

Dr. Prabhakar Clement

The lead RT3D developer is Dr. Prabhakar Clement, who is the Director of the Center for Water Quality Research and a professor of environmental engineering at the University of Alabama. Dr. Clement's work on RT3D began at PNNL and continued as he was a senior lecturer at the University of Western Australia, professor of civil engineering at Auburn University, and now at the University of Alabama.

Contact: Dr. Prabhakar Clement

Chris Johnson

Johnson is a senior development engineer at PNNL who develops aspects of RT3D, notably reaction modules and customizations for specific applications applicable to active remediation and natural attenuation. In addition to code development, Johnson performs code testing, writes code documentation, oversees distribution of the RT3D code, and is the primary contact for questions on application of the RT3D code.

Contact: Chris Johnson

Pacific Northwest National Laboratory (PNNL)

The Pacific Northwest National Laboratory in Richland, Washington is a U.S. Department of Energy Office of Science national laboratory where interdisciplinary teams advance science and technology and deliver solutions to America's most intractable problems in energy, national security, and the environment. PNNL employs over 4,500 staff, has a $1 billion annual operating budget, and has been managed by Ohio-based Battelle Memorial Institute since the laboratory's inception in 1965.