Innovative 2-Phase Extraction method provides low permeability site remediation alternative

2-Phase Extraction is an innovative remedial process developed and patented by Xerox Corporation that combines the attributes of soil vapor extraction and groundwater recovery under high vacuum (>25 inches Hg at the source) in a way that synergistically increases the performance of the collective remedy. The process application uses simple, skid mounted equipment which eliminates the need for pump installations in recovery wells and reduces the total number of recovery locations. Extraction can be successfully accomplished from 2 inch diameter monitoring wells as an interim measure and for pilot evaluation of the technology. In many instances, additional extraction points can be minimized, reducing the cost of the installed remedy. The extraction process strips groundwater with soil vapors during recovery, and pretreats both recovered phases, reducing the cost for treatment equipment installation and operation. The extraction unit is modular and can be used with a wide variety of vapor and liquid treatment processes based on site economics. Haley and Aldrich has applied 2-Phase Extraction on a number of low permeability sites with a wide range of geologic conditions. Their paper focuses on an overview of results achieved at 4 of the sites under pilot and full scale operations. Soil permeabilities have ranged as low as 10-7 cm/sec, with shallow to moderate overburden overlying fractured bedrock, or fine grained silts, sands and clays. Contaminant plume characteristics varied from Non Aqueous Phase Liquids (NAPL) to dissolved phase plumes transported in low permeability fractured bedrock aquifers. Contaminants successfully extracted have ranged from petroleum products to blends of chlorinated solvents and mineral oils