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CHARACTERIZATION AND REMEDIATION TECHNOLOGIES FOR LIGHT NONAQUEOUS PHASE LIQUIDS
Citation:
Acree*, S. CHARACTERIZATION AND REMEDIATION TECHNOLOGIES FOR LIGHT NONAQUEOUS PHASE LIQUIDS. Presented at Fuels Management Workshop, USEPA Region 9, Honolulu, HI, 1/17-18/01.
Description:
Light nonaqueous phase liquids (LNAPLs), principally petroleum products, affect ground-water quality at numerous sites across this country and throughout the world. Petroleum products are typically multi-component organic mixtures composed of chemicals with a wide range of solubilities and other physical and chemical properties that control their transport and fate in the subsurface. Some components such as ether additives are highly soluble and mobile in ground water while others such as polyaromatic hydrocarbons have relatively low solubilities and mobility. The release of these products often results in formation of source areas for continuing ground-water contamination where contaminant concentrations are high and LNAPL may be present as free product and/or residual contamination trapped in soil pores. Based on differences in the nature and distribution of contaminants in the source area and the downgradient plume, different remedial technologies are applicable in each area.
Data generally required for evaluation of remedial technologies include information on the physical/chemical properties and distribution of the LNAPL and its components, hydrogeologic data, and remediation objectives. The most appropriate tools and techniques for obtaining this information depend on site conditions and include conventional drilling and sampling methods as well as rapid site assessment techniques using push technologies and field analytical methods. In general, the transport and distribution of petroleum products in the subsurface are often complex due in large part to heterogeneity in subsurface materials and product release histories. Despite this complexity, adequate characterization to support evaluation of remedial options and designs is necessary for implementation of effective and efficient remediation systems and should ultimately result in significant cost savings.
Remedial objectives and site characterization data dictate the most appropriate remediation technologies. Potential technologies range from conventional techniques such as excavation and free product recovery using wells or drains to various alternative technologies. Conventional product recovery techniques include recovery of only product, recovery of a combined stream of product and water, recovery of volatile components in the vapor phase, and variations of these general methods. Remediation technologies often applied to the dissolved plume include pump-and-treat, bioremediation, and reliance on natural processes (e.g., dispersion and biological transformation) to reduce contaminant concentrations and control migration.