Design and application of an alternative groundwater sparging technology

Density-driven convection, an alternative method of in situ groundwater sparging, is being used to remediate 27 underground storage tank releases involving a wide distillation range of petroleum hydrocarbons (gasoline to waste oil) in a variety of site soils (silty clay to sandy gravel). The described method overcomes many of the inherent disadvantages of air sparging methods currently in use (such as pressurized injection) without additional complexity in design, installation, or operation. The principles of operation and design for density-driven convection are discussed in detail and supported by field and laboratory studies. Primary factors affecting the hydraulic driving force, groundwater circulation patterns around the sparging well, and air stripping performance are identified and related to system design. The effectiveness of the system is demonstrated with results from full-scale system installations