Case study: In-situ methods for the recovery of dissolved and free-phase TCE

Two-phase vacuum extraction (VE) technology, which simultaneously removes groundwater and soil vapor from the subsurface, has been applied at a dense non-aqueous phase liquid (DNAPL) site with promising results. The two-phase VE (a.k.a. dual-phase VE) has been used to enhance groundwater recovery to attain a zone of capture by enhancing groundwater yields from groundwater recovery wells not attainable from pumping alone. Operation of the two-phase VE system has resulted in the recovery of significant quantities of DNAPL, consisting primarily of trichloroethylene (TCE). Controlled pumping has been applied to recover the free-phase TCE. This paper presents a summary of site conditions, description of the two-phase VE and groundwater remediation system, and conclusions from the site remediation.