Recent developments in laboratory analytical techniques, when combined with application of multivariate statistical analyses allow differentiation and delineation of comingled NAPLs and resultant contaminant plumes. The increase in laboratory expertise and a growing body of relevant studies in case literature have made possible evaluation of petroleum impacted media through relatively standard techniques a reality, and well within the realm of economical site assessments. The application of several methods to determine the number, type, and timing of multiple NAPL releases at a commercial facility in an urban setting will be summarized. The combination of chemical, historical, and statistical techniques has allowed for a more complete evaluation of NAPL sources and release histories than was initially thought possible. In the examined case, overlapping NAPL plumes are defined, delineated, and identified; and source identifications for individual releases are completed. These evaluations resulted in identification of previously unconfirmed sources, improved characterization of the nature of NAPL present, and refined fate, transport, and feasibility evaluations for the conceptual site model
