Subsurface Point-Source Contamination

Intensive field investigations are established at representative sites contaminated with predominant types of environmental contamination, in commonly occurring geohydrologic and geochemical settings. Contamination types currently under investigation include chlorinated solvents, sewage effluent, toxic metals, radionuclides, and petroleum products, including fuel oxygenates. These long-term research projects are conducted by interdisciplinary research teams that comprehensively identify and characterize the physical, chemical, and biological processes that affect contaminant transport, transformation, and fate at the site. Through extensive characterization and field experimentation, the sites provide field-laboratory conditions that enhance research opportunities. Results from the sites are generalized by focused field and laboratory experiments at other sites that describe the range of field conditions for the controlling processes. Simulation models are developed to assist with the design of monitoring and remediation of subsurface contaminant plumes. Knowledge and tools produced at these representative sites improve the effectiveness and reduce the cost of characterization and remediation at similar sites across the Nation.

A unifying theme of these investigations is characterization of the natural response of hydrologic systems to contamination. This, when combined with comprehensive assessment of the processes that affect contaminant transport and fate, make assessing the potential of natural attenuation and remediation-performance monitoring undertakings in which the Toxics Program can excel. The long-term nature of the research provides a unique opportunity to evaluate the potential and limitations of natural-attenuation remediation alternatives.