A Geospatial Model for Remedial Design Optimization and Performance Evaluation
Soil and ground water remediation projects require collection and interpretation of large amounts of spatial data. Two-dimensional (2D) mapping techniques are often inadequate for characterizing complex subsurface conditions at contaminated sites. To interpret data from these sites, we developed a methodology that allows integration of multiple, three-dimensional (3D) data sets for spatial analysis. This methodology was applied to the Department of Energy (DOE) Building 834 Operable Unit at Lawrence Livermore National Laboratory Site 300, in central California. This site is contaminated with a non-aqueous phase liquid (NAPL) mixture consisting of trichloroethene (TCE) and tetrakis (2-ethylbutoxy) silane (TKEBS). In the 1960s and 1970s, releases of this heat-exchange fluid to the environment resulted in TCE concentrations up to 970 mg/kg in soil and dissolved-phase concentrations approaching the solubility limit in a shallow, perched water-bearing zone. A geospatial model was developed using site hydrogeological data, and monitoring data for volatile organic compounds (VOCs) and biogeochemical parameters. The model was used to characterize the distribution of contamination in different geologic media, and to track changes in subsurface contaminant mass related to treatment facility operation and natural attenuation processes. Natural attenuation occurs mainly as microbial reductive dechlorination of TCE which is dependent on the presence of TKEBS, whose fermentation provides the hydrogen required for microbial reductive dechlorination of VOCs. Output of the geospatial model shows that soil vapor extraction (SVE) is incompatible with anaerobic VOC transformation, presumably due to temporary microbial inhibition caused by oxygen influx into the subsurface. Geospatial analysis of monitoring data collected over a three-year period allowed for generation of representative monthly VOC plume maps and dissolved-phase mass estimates. The latter information proved to be invaluable in optimizing and evaluating the remedial design and performance.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15005954
- Report Number(s):
- UCRL-JC-147302; TRN: US200402%%241
- Resource Relation:
- Conference: Third International Conference on Remediation of Chlorinated and Recalcitrant Compounds, Monterey, CA (US), 05/20/2002--05/23/2002; Other Information: PBD: 19 Feb 2002
- Country of Publication:
- United States
- Language:
- English
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