Physical modeling of air flow during air sparging remediation.

Air sparging (AS) is one of the most efficient techniques for remediating saturated soils and groundwater contaminated with volatile organic compounds. A series of physical modeling tests for different sizes of porous media under varied injection pressure were conducted to investigate the effect of particle size and air injection pressure on size and shape of the zone of influence (ZOI). The test results show that ZOI can be expressed by two components: the horizontal expansion due to pneumatic fracture or preferential intrusion around the injection point and the angle of ZOI which is the angle between the vertical line and the boundary of ZOI. There exists a limited angle of ZOI for each type of porous media. The measured minimum and maximum air injection pressures in 1g tests are compared with corresponding theoretical values, and it is found that the measured minimum injection pressure is slightly lower than the theoretical value, while the measured maximum injection pressure is much higher than the theoretical maximum injection pressure. Centrifugal test results confirmed nonapplicability of theoretical maximum injection pressure to air sparging design. All of the above provide valuable information for design and theoretical modeling of air sparging for groundwater remediation.