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2.2 Processing 2-D resistivity data was modeled using the program Earthlmazer 2D v2.0.1 by Advanced Geoscience, Inc, 2005. Preliminary data processing was conducted in the field and the final data processing was completed in the office at a later date. Prior to data modeling, a number of preprocessing steps were completed. Preprocessing steps consisted of the following: Backup of all original field data files to disk Conversion of elevation data to a comma-delimited text file via Microsoft ExcelTM Loading data into EarthImager2D and removal of data spikes and bad readings Set inversion parameters in EarthImager2D A least-squares inversion of the resistivity data was then conducted using a finite element mesh with surface topography to generate a 2-D model of resistivity versus depth/elevation. Output of the resistivity model and inversion parameters were saved digitally in ASCII format containing position, elevation and apparent resistivity. These data were converted into free format XYZ files and imported into the Oasis Montaj mapping system for presentation. Presentation of 2-D resistivity cross sections included the following: Reformatting of data files to GEOSOFT® format. Generating final map scale. Gridding data using minimum curvature. Masking grid in areas where data not acquired (i.e. around site perimeter or building). Applying Harming filter to smooth the data, as necessary. Generating color zone file describing color for different data ranges. Contouring the data. Generating map surrounds (title block, legend, scale, color bar, etc.) Annotating anomalies. Merging various plot files and plotting final map. The names of the files generated and the processing parameters used were documented and are retained in project files. All files generated during the processing sequence were archived on CD-ROM. 6243 Versar 3 July 6, 2006