A successful steam-enhanced treatment of a TCE DNAPL source area occurred at an active manufacturing facility. I provided technical support to a small Oregon consulting firm for enhanced bioremediation of residual TCE post thermal. Treatment included emulsified vegetable oil (EVO) as the donor and bioaugmentation to recolonize the "steam-cleaned" aquifer. Thermal treatment had provided a favorable starting ground water temperature of 28 degrees C. The pilot test involved placement of a short biobarrier via recirculation wells and used a dye tracer to establish breakthrough.
Residual TCE concentrations down gradient were reduced from greater than 100 ug/l to ND at all monitoring points, and more than half of the low levels of vinyl chloride generated were reduced to ethene in less than six months (Lehmicke et al. 2006). Full-scale treatment was implemented successfully at three other areas on site and an off-site area. The Site was granted No Further Action status in 2010.
