Studies by the U.S. Geological Survey (USGS) have shown that microorganisms naturally present in soil were actively consuming fuel-derived toxic compounds and transforming them into harmless carbon dioxide. Furthermore, these studies have shown that the rate of these biotransformations could be greatly increased by the addition of nutrients. By "stimulating" the natural microbial community through nutrient addition, it was theoretically possible to increase rates of biodegradation and thereby shield the residential area from further contamination.