ESTCP 2017 Project-of-the-year Award for Environmental Restoration
1,4-Dioxane, a cyclic diether used as an additive in chlorinated solvents is a common and persistent groundwater contaminant. While conventional soil vapor extraction (SVE) can remove some 1,4-dioxane, a substantial residual source is left behind causing long-term groundwater contamination. Due to the compound’s complete miscibility in water, 1,4-dioxane becomes sequestered in the vadose zone pore water which serves as a long-term source of groundwater contamination.
Dr. Rob Hinchee from Integrated Science & Technology, Inc. and his team led a project that aimed to evaluate and demonstrate the efficacy of enhanced or extreme soil vapor extraction (XSVE) designed specifically to remove 1,4-dioxane from the vadose zone by incorporating enhancements such as increased air flow, increased temperature and focused vapor extraction. A screening-level mass and energy balance model, HypeVent XSVE, was developed to simulate the remediation of 1,4-dioxane by XSVE.
The study results indicate that 1,4-dioxane concentrations in the treatment zone decreased about 95% and soil moisture decreased about 45%. Downward migration of 1,4-dioxane due to condensation was not observed. HypeVent XSVE adequately simulated 1,4-dioxane removal, soil moisture and soil temperatures observed during the demonstration. Sensitivity analyses showed that 1,4-dioxane removal benefited considerably from heated air injection.
XSVE has been demonstrated to be a cost-effective remediation approach 1,4-dioxane in the vadose zone, which may reduce the need for long-term groundwater remediation. HypeVent XSVE has been demonstrated to be a useful feasibility assessment and design tool for XSVE of 1,4-dioxane.
For this significant work, Dr. Hinchee and his team received the 2017 ESTCP Project of the Year Award for Environmental Restoration for their project titled 1,4-Dioxane Remediation by Extreme Soil Vapor Extraction (XSVE).