JSHEEHAN:
I assume what you are doing is injecting air into porous soil to stimulate "friendly" biological decomposition of a contaminent(s). Other people may feel differently, but I have my doubts about air sparging. You are dependent upon the porosity of the soil for infiltration of the air. There are a lot of sparging heads that are required for any appreciable area.
If the contaminent is shallow you can simply do a bioremediation by adding microbes, water, and food. Aerate and turn the soil frequently.
Could you please supply some more details such as contaminent(s), area, depth, etc.
Thanks
Dave