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IN SITU, LOW TEMPERATURE THERMAL REMEDIATION OF LNAPL WITH PESTICIDES AND OTHER RECALCITRANT COMPOUNDS
Dablow, J., J. Baldock, J. Dinham, and K. Johnson.
RemTech 2017: Remediation Technologies Symposium. Presentation 33, 23 slides, 2017

Site investigation activities at a former pesticide manufacturing plant in the UK identified impacts from kerosene and dieldrin to saturated gravels that overlie the regional chalk bedrock. LNAPL was encountered in site wells and a contaminant mass of ~7,000 kg was estimated in the target source zone. To mitigate the risks presented by the LNAPL and high levels of dieldrin to a nearby river and the groundwater in the chalk aquifer, a source-zone remediation strategy was evaluated and implemented. A high-temperature strategy using in situ thermal destruction was modeled and evaluated initially, but attaining the target temperature was problematic, which led to the development of an innovative strategy of steam-enhanced extraction to mobilize rather than volatilize the LNAPL at lower temperatures. Following a bench-scale treatability study, a full-scale system was designed and constructed at the site. Steam injection together with simultaneous vapor and liquid recovery began in April 2017. The target source zone was brought up to temperature slowly through controlled injection of steam. LNAPL mobilization was observed as temperatures approached 70°C. The majority of the mass was removed as NAPL at average soil temperatures between 70-80°C. Isolated hot spots were addressed in June 2017 with in situ chemical oxidation using persulfate activation via sodium hydroxide.
Longer abstract: www.esaa.org/wp-content/uploads/2017/09/RemTech2017Abstracts-33.pdf
Slides: http://www.esaa.org/wp-content/uploads/2017/10/17-Dablow.pdf



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