IAS works by forcing vapor flow through the aquifer and collecting volatile contaminants in the vapor stream as it passes through contaminated zones.  IAS also adds oxygen to the system, which can enhance biodegradation of amenable compounds.

Unlike most other remediation methods, IAS generates flow gradients away from the center of contaminant mass.  It can also mobilize free and trapped contaminant oils (NAPL) and push them to new locations.  These attributes can cause rapid and deleterious effects to surrounding buildings, people, and other receptors.  Therefore, the utmost care in planning and design is necessary for this remediation method.

For most in the industry, IAS has been designed using a field parameter called the radius of influence.  ROI is a real measurement, but by itself has very little to do with the effectiveness of IAS or lack thereof.   Similarly, SVE is typically used to capture fugitive vapors from IAS, and it needs to be designed on a flow basis, not an ROI basis.  Flow rates and paths relative to the target contamination and where IAS exits the water table are the key attributes to successful sparging design.  Because both air and NAPLs are non-wetting fluids, design synergies exist for sparging that are rarely recognized by most practitioners. 

An efficient IAS design will collect more contaminant mass in less time and at less cost than a system designed by ROI methods.  Both well-designed and poorly designed systems will go asymptotic, but the well-designed system leaves much less residual contamination and therefore greatly reduces the risk and potential liability.  Poorly designed systems often leave zones of original contamination untouched, and therefore provide no real value because the risk & liability are unchanged.