Formatted Title
Using Three-Dimensional Modeling for Optimizing Investigation and Remedial Injection Programs at CVOC-Contaminated Sites
Background/Objectives
Chlorinated volatile organic compounds (CVOCs) in groundwater are being addressed at a former plating shop and two dry cleaner sites in the San Francisco Bay area. An efficient site characterization, remedial design, and implementation schedule was desired for all three projects to fit redevelopment plans. The major objectives were to 1) delineate the CVOC plumes, identify areas of elevated concentrations, and identify potential preferential flow paths, and where applicable, 2) target optimal locations for in situ remediation using combinations of abiotic chemical reduction, enhanced reductive dechlorination, and permeable reactive barriers. Regularly updated three-dimensional implicit site models were used during the site characterization and remedial design phases to define injection target zones, and then adapted to support field implementation and testing. Real-time results from the investigation and updates to the model supported an adaptive field program where adjustments to the drilling, sampling, or injection schedule could be made on-the-fly.
Approach/Activities
Using three-dimensional implicit modeling we plotted the CVOC plumes with zones of estimated relative hydraulic conductivity using limited and varied site information to build adaptive conceptual site models that have been used throughout the project. The models were used as 1) a planning tool for data gap analysis, 2) a remedial design tool by visualizing injection points and predicting injectability at each injection interval, 3) an injection optimization tool combined with real-time field monitoring during injection testing and implementation, and 4) a site conceptualization tool for key stakeholder communications and decisions.
Results/Lessons Learned
Three-dimensional modeling was very effective in supporting site characterization for three case studies, streamlining the approach at hydrogeologically complex sites. The models accelerated and optimized in situ remediation injection programs to meet redevelopment and funding scheduling challenges through the design and remedial action phases, while providing an adaptive tool during remedial implementation to help meet performance criteria.