A fifth treatment plant for contaminated wastewater at the Tucson International Airport Area Superfund site now is under construction and expected to be completed next spring, report EPA officials report.
Construction has just started on the new plant on the west side ofthe site, notes remedial project manager Matthew Jefferson. That plant represents "the last component that is part of the remedy" at the site, Jefferson adds. The facility is intended to process shallow groundwater and "some vapors" from contamination due to trichloroethylene (TCE), he explains. The site was placed on the National Priorities List in 1982.
The Superfund location covers an area of approximately 10 square miles, including the airport, portions of an Indian reservation, residential areas in Tucson and South Tucson and the site of Air Force Plant No. 44, Raytheon Missile Systems. Co., EPA reports.
At least 20 separate facilities operated at the site since 1942, including aircraft and electronics facilities that discharged waste liquids directly into the soil; fire drill training areas, where wastesfrom training operations were left in unlined pits, and unlined landfills that received various wastes from a number of sources, according to EPA officials. Large-scale waste disposal occurred at the missile plant during the 1950s, EPA reports.
The facility was a government-owned plant operated under contract by Raytheon Missile Systems Co., formerly known as Hughes Missile Systems Co. The plant was operated by Hughes or its subsidiaries from its construction in 1951 until it was purchased by Raytheon in 1997.
Beginning in 1976, EPA reports, lined wastewater holding ponds were constructed to receive wastewater discharges, with 35 ponds in place by 1987. In 1997, the missile plant completed upgrades to its wastewater treatment system and has become a non-discharging plant that recycles 97 percent of its water.
EPA also identified problems at the airport property--specificallythe Airport Three Hangar Area--that was occupied by various defense contractors, including McDonnell Douglas Corp., Grand Central Corp. and General Dynamics Corp. In 1981, EPA and Tucson investigators sampled groundwater from city wells within the airport property and found "unsafe levels" of TCE.
Subsequent investigations identified a main plume of groundwater contamination approximately one-half mile wide and five miles long linked to the site, and additional municipal and private water wells in the vicinity were shut down, according to EPA officials.
Several consent decrees were signed with potentially responsible parties during EPA's activities at the site. In 2002, EPA announced extraction and treatment of the contaminated groundwater at the site asits preferred cleanup option.
As of last year, figures compiled by EPA showed more than 40 billion gallons of groundwater and more than 130,000 pounds of volatile organic compounds (VOC) had been removed from the site.
In addition, 100,000 tons of metals, 10,000 tons soil contaminatedwith polychlorinated biphenyls (PCBs) and 2,000 tons of PCB and VOC contaminated sludges have been removed.
EPA reports that as a result of activities at the site, contaminated drinking water supplies have been removed from service and actionshave been taken to control and prevent future contamination. "The general public is not being exposed to the Superfund contaminants," EPAcomments.
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