DNAPL characterization methods and approaches, part 1: Performance comparisons

Contamination from the use of chlorinated solvents, often classified as den se nonaqueous phase liquids (DNAPLs) when in an undissolved state, represen ts an environmental challenge with global implications. Mass-transfer limit ations due to rate-limited dissolution can lead to longterm aquifer persist ence for even small volumetric fractions. The identification of DNAPL sourc e zones located beneath the water table is critical to ultimately achieve s ite remediation and aquifer restoration. This paper provides a comparison o f the advantages and disadvantages of many of the methods being used for de tecting and delineating DNAPL contaminant source zones. The objective is to determine which options are best to pursue based on site characteristics, method performance, and method costs. DNAPL characterization methods are gr ouped into approaches, which include site preparation, characterization, an d data-processing activities necessary to design an effective remediation s ystem. We compare the different approaches based on the level of chemical a nd hydrogeologic resolution, and the need for additional data requirements. Our findings can be used to assist with selection of appropriate site reme diation management options.