On uncomplicated sites with layer-cake geology, a reliable geological site model can be produced from a few sparse boreholes. With increasing geological complexity, a greater density of boreholes is required to properly characterize the site, resulting in increased environmental impacts. Geophysical methods have thus become attractive for site characterization projects because they can fill in the gaps between boreholes without disturbing the ground and at a much lower cost than for an expanded geological drilling program. Moreover, geophysical surveys can be conducted prior to a drilling program, with the goal of optimizing locations for subsequent boreholes.