A process for in situ biodegradation of hydrocarbon contaminated soil.

The present invention is a process for in situ biodegradation of spilled hydrocarbons. The process involves drawing oxygen into a hydrocarbon contaminated zone (10). A borehole (8) is drilled into the contaminated zone (10) and gas is evacuated at high rates out of the borehole via a gas exhaust line (12) to thereby draw oxygen into the contaminated zone (10). Surprisingly, the carbon dioxide concentration in the evacuated gas remains high even at the high flow rates.