A large-dilute (L&D) plume can be informally defined as: A plume of relatively low concentration that extends over a great distance. Many L&D plume lengths are scaled to “km” or “miles” rather than “m” or “ft.” For chlorinated solvent contamination, L&D plumes often occur in permeable aquifers and in aerobic settings with low organic carbon. In these conditions, attenuation processes are relatively slow (e.g., degradation halflife more than 1 to 5 years) and plume structure and persistence are impacted by mass transfer in/out of less transmissive compartments such as clay and silt layers. Examination of L&D chlorinated solvent plumes from across the U.S., supported by a parametric modeling study, provided insights and refined conceptual models related to L&D plumes: for a particular condition what is the expected plume size, plume structure, and important contaminant attenuation processes and rates? Key findings from the parametric evaluation:
展开▼
