Abstract: 3D Geoscience Modeling and Visualization Techniques to Characterize Vadose Zone Contamination and Streamline Cleanup Decisions

Randall F. Hedegaard, Dan A. Miller, Jack Murphy

Procedures for estimating contaminant distribution, analyzing geostatistics, and the 3D visualization of the subsurface have been made possible through the use of software such as: LYNX GMS^TM, Wavefront's Data Visualizer^TM, and Gstools (public domain). These tools have been used successfully to provide a central platform from which to map a contaminant plume, visualize the same plume three dimensionally, and calculate volumes of contaminated soil or groundwater above important health risk thresholds. The methodology developed allowed rapid data inspection for decisions on remedial action design through interaction with a database. The result is improved detail of analysis and increased effectiveness of presentation to the client.

Ten sites at an Air Force installation in California were taken from Remedial Investigation through to Treatability Study phase, each with a 3D geoscience model of vadose zone soil contamination. Soil volume, average concentration, and contaminant mass were calculated for both soil and gas data using several risk-based thresholds. The geometry of each plume was estimated using 3D variography on raw analyte values and indicator thresholds for the kriged model. 3D lithologic interpretation was based on either ???linked??? parallel cross sections or on kriged grid estimations derived from borehole data coded with permeability indicator thresholds. Investigative borings as well as soil vapor extraction/injection wells were sited and excavation costs were estimated using these results. Cro s sections, fence diagrams, 2D contaminant maps, 3D renderings of site contaminant volumes and geology, and animation were also produced.

AAPG Search and Discovery Article #90958©1995 AAPG Pacific Section Meeting, San Francisco, California