The use of migration barriers to prevent the spread of petroleum hydrocarbons

Contaminant containment at a remediation site can be achieved in several ways, depending upon the geochemical characteristics of the site, the nature and intensity of the contamination, and the phase distribution of the contaminants. In sites involving a contamination solute plume in groundwater, the containment issue has classically been achieved with some form of hydraulic extraction system, where elevation gradients have been achieved by pumps in vertical (or horizontal) wells. Plumes of solute contaminants in the aquifer have been captured by closure of the flow lines at the extraction well(s) location and the extracted water transported to a treatment system for removal of the dissolved contaminant species. While frequently referred to as ''pump and treat,'' such systems are not true treatment concepts and usually fail to address the ''source'' which exists upgradient in the form of oily-phase ''free'' adsorbed or entrained phases in the aquifer material itself. The use of air sparging techniques to effect both physical removal and biological degradation and the use of a row of wells containing a slow release oxygen compound are discussed as methods of mitigating migration of monoaromatic hydrocarbons (BTEX) and other volatile and/or aerobically biodegradable contaminants