EM Technology Program Update: New Approach to Assess Volatile Contamination in Vadose Zone Provides Path Forward for Site Closure

April 24, 2012 RICHLAND, Wash. and LOS ALAMOS, N.M. – Through the Deep Vadose Zone-Applied Field Research Initiative (DVZ-AFRI), scientists and engineers from Pacific Northwest National Laboratory, CH2M HILL Plateau Remediation Company, federal agencies, and the scientific community are collaborating to develop effective, science-based solutions for remediating, characterizing, monitoring, and predicting the behavior and fate of deep vadose zone contamination. DVZ-AFRI is supported through a memorandum of understanding with EM’s Office of Soil and Groundwater Remediation and the Richland Operations Office. This partnership is maximizing resources to facilitate development of the scientific and technical foundation and technologies needed to make sound and defensible remedial decisions that will successfully meet target cleanup goals. Soil vapor extraction (SVE) is a baseline remediation approach applied at many sites to remove volatile contaminants from the vadose zone. While SVE generally removes contaminants from most parts of the vadose zone, many sites have low-permeability heterogeneities that limit the ability of SVE remediation and leave residual, persistent zones of contamination. Under these conditions, a risk informed evaluation of SVE performance should determine if the system needs to be optimized, terminated, or transitioned to another approach.