Development of Assessment Tools for Evaluation of the Benefits of DNAPL Source Zone Treatment

摘要

Since its commencement in September 2002, SERDP Project ER-1293 has supported 4 doctoral students at three universities and resulted in over 40 conference proceedings/technical abstracts and over 20 peer-reviewed publications. These presentations and publications, as referenced in this final report, describe various aspects of the research investigations and tools that have been developed to enhance design and assessment of DNAPL source zone treatment. In general, research in ER-1293 has led to the development and validation of four important concepts: (1) partial source zone mass removal may result in substantial local concentration and mass flux reductions; (2) potential remediation efficiency is closely linked to source zone architecture (ganglia to pool ratios); (3) biostimulation and bioaugmentation approaches are feasible for treatment of DNAPL source zones; and (4) the uncertainty in mass discharge (M/T) estimates can be quantified through application of geostatistical methods to field measurements. Major contributions of this research include (1) establishment that rates of metabolic reductive dechlorination can exceed rates of DNAPL dissolution, resulting in aqueous contaminant concentrations in the presence of DNAPL that are substantially lower than saturation levels and are not toxic to the dechlorinating organisms; (2) enhancements in dissolution will be transient and a function of physico- chemical and biological conditions adjacent to the DNAPL; (3) demonstration that mass flux reduction behavior can be directly linked to DNAPL source zone architecture; (4) development of a series of geostatistical approaches capable of quantifying mass discharge uncertainty and guiding real-time sampling design for uncertainty reduction through hot spot delineation; and (5) creation of a source zone remediation cost estimation tool.