Releases of fuel hydrocarbons and chlorinated solvents from a former underground waste management unit at an aviation maintenance facility have resulted in impacts to soil and groundwater. Groundwater occurs in a confined sandy clay zone 14 feet below ground surface. The waste management unit was removed in 1991, however complete source removal was not completed due to the proximity of the maintenance facility. As a result of the fuel hydrocarbon releases, strongly reducing conditions have been created in the source area. This has resulted in reductive dechlorination through dehalorespiration. Outside the source area, aerobic conditions exist, resulting in biologically mediated oxidation of fuel hydrocarbons and chlorinated solvent daughter products, including vinyl chloride. The overall rate of natural attenuation in groundwater is sufficient to prevent plume migration, allowing for site closure with no further active remediation. In addition to examining the interaction of the fuel hydrocarbons with the chlorinated solvents, the impact of naturally occurring inorganic electron acceptors on plume behavior is discussed.