Distribution and movement of trichloroethylene in ground water in the Tucson area, Arizona

In 1981, investigations of groundwater quality around Tucson International Airport revealed a number of wells that pumped water contaminated with trichloroethylene. Subsequent investigations resulted in the delineation of three distinct areas of contamination, the largest of which encompasses about 5 sq mi of aquifer surface area. Most of the contamination is in the top 100 ft of the saturated groundwater flow system. A fine-grained confining layer that is present in much of the contaminated area significantly limits the vertical movement of the chlorinated groundwater. Within the contaminated area, measured trichloroethylene concentrations were as high as 3,100 mg/L in 1984. Measured concentrations are highly variable vertically as well as horizontally. Future quantitative studies of contaminant movement may benefit from additional data collection and experiments to determine which contaminant transport and groundwater flow equations are most appropriate.