Successful remediation depends on accurate site characterization. Over the past decade, tools for cost effective, high density data collection have matured. These tools include contaminant detection tools and tools for collection and real-time analysis of soil and groundwater (GW). Direct sensing tools are now available that collect high density geologic and hydrogeologic data that provide important information to guide site investigation decisions as well as remedial design. Site characterization has come a long way. Now even the most complex sites can be effectively characterized in a reasonable amount of time to reduce the total project cost from planning to site closure.