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Research

Current Projects

Metric Identification and Protocol Development for Characterizing DNAPL Sources Zone Architecture and Associated Plume Response
Sponsor: Strategic Environmental Research & Development Program
Primary Investigator: Linda M. Abriola

Model DNAPL Source Zone Architecture and Down-Gradient Plume Evolution at the Field-Scale.
During the first 3 years of this project (March 2008- February 2011) a suite of field-scale numerical simulations were performed using an existing numerical, multiphase compositional simulator. NAPL infiltration, plume development and NAPL depletion simulations were obtained in an ensemble of 30 three-dimensional hydrogeologic realizations with varying degrees of heterogeneity. During the current year of the project (March 2011- February 2012) additional source zone architectures will be obtained by modeling different configurations of hydrogeologic realization, spill and NAPL characteristics (such as the release rate, the number of sources, the length of release, NAPL density, and NAPL composition). These NAPL source zone architectures will serve as initial conditions for the simulation of plume development and NAPL depletion using the modular three-dimensional transport simulator (MT3DMS) modified to simulate NAPL dissolution. Simulation results will be used for signal processing during Task III. Each source zone distribution will be quantified using traditional and recently proposed metrics such as the maximum organic saturation, the first and second spatial moments, and the ganglia-to-pool ratio as well as newly derived metrics. Plume response will be quantified using flux-averaged concentration and source longevity. In this way, links between the source zone architecture and plume response may be elucidated during the signal processing performed under Task III.

Development of Simplified Modeling Tools for Initial Site Screening.
Knowledge gained during other aspects of the project will guide model development toward a predictive tool that links plume response to source zone architecture. Expressions will be developed to enable the prediction of down-gradient contaminant flux for a given level of mass removal and source longevity. The focus will remain on simplified expressions that are easily integrated into common software (e.g., Excel, Matlab) to facilitate the dissemination of the model to site managers, regulators, and administrators. Screening model refinement and validation will employ laboratory experiments, numerical simulations, and field-derived data obtained under other aspects of the project. Following model refinement, model predictions will be used to evaluate plume evolution assuming various source zone architectures, where each revised source zone architecture corresponds to a given method and level of DNAPL removal. Knowledge gained through model analysis and application will be incorporated into the protocol developed in Task IV to guide practitioners.