New building construction planning typically includes site characterization with standard geotechnical drilling and sampling methods under the direction of a professional engineer. For project sites with the potential for variable types and thicknesses of fill materials, including contaminated wastes that pose a possible environmental hazard, this traditional site characterization approach can result in under sampling and lead to an unrepresentative site characterization. This can also result in significant cost overruns and other surprises. In recent years, as reuse of 'brownfield' properties has increased, the need for better, more reliable site characterization methodologies has grown. The combined use of geophysical surveys and standard drilling and sampling methods during the project planning phase has been shown to be a valuable approach to meet these needs. This paper presents a case history of an actual construction project in which geophysics was combined with traditional drilling and sampling at a brownfield location where a 70,000 cubic yard excavation for two commercial building basements was planned. Historical information combined with the initial drilling results and geophysical testing revealed a potential two-dimensional bias to the fill distribution. Closely-spaced, 2-dimensional resistivity profiles were independently acquired and inverted, and then jointly interpolated in 3-dimensions to render a 3-dimensional image of the fill materials. The 3-dimensional imaging allowed for the quantification of fill types and quantities for proper management during excavation, and the development of estimates for transportation and disposal of the materials. In addition, it also allowed the construction management team to plan for proper segregation and handling of these materials to minimize total construction costs and schedule delays while maintaining safe working conditions.

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