Surfactant Enhanced In-situ Remediation of DNAPL Impacted Soil and Groundwater - Montreal Refinery Case Study

A Montreal chemical refinery reduced the dichlorobenzene and other dense non-aqueous phase liquid (DNAPL) impacts on the soil and groundwater where a railway line is adjacent to an above ground storage tank farm. Ivey-sol surfactant mixtures were injected three times during a two week pilot test, into a series of in-situ wells. The soil and groundwater matrix experienced an induced partial vacuum of 75 mm Hg (mercury). Recovery well water samples were analyzed for concentrations of specific DNAPL (Chlorobenzene and Dichlorobenzenes) and BTEX (benzene, ethylbenzene, xylenes, and toluene) solvent “compounds of concern”. Groundwater recovery flow rates were documented and recovered mass estimates were calculated. Compared to projected baseline conditions and efforts, the surfactant enhanced in-situ remediation efforts in this case study, resulted in a significant incremental increase in the recovered mass of the DNAPL and BTEX “compounds of concern”, which had impacted the soil and groundwater. The mass recovery increased by over 500% for the DNAPL compounds, plus an additional 50% of DNAPL mass recovered as free product. Compared to the results of three years of earlier efforts by others, the client was quoted as finding this approach to be a “rapid and cost effective method to achieve site clean up.”