Effect of system variables and particle size on physical characteristics of air sparging plumes

Air was injected through a well in a thin transparent tank filled with saturated glass beads to study how the size and air saturation of air sparging plumes are affected by particle size and gradation; operational parameters such as injection pressure, well depth, injection pressure pulsing; and well outlet configuration. V-shaped air plumes with an apex between 40° and 60° were obtained for all tests. The air pressure required to initiate sparging agreed closely with the sum of the air entry pressure and the hydrostatic pressure, with higher initiation pressures required in the fine and well-graded beads. Higher air flow rates and air saturations were obtained in coarser beads at a given pressure, and the variation in flow rate was consistent with estimated air permeabilities. Peak average air saturations were 28–56% for the coarse-medium beads, 10% for the well-graded beads, and 8% for the fine beads. Air saturation and the radius of influence increased modestly (