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The Tucson International Airport Area (TIAA) Superfund site is geographically situated in the northern portion of the Tucson Basin in Pima County, Arizona, south of the intersection of U.S. Interstate Freeways 10 and 19, and includes the south side of the city of Tucson. The Santa Cruz River runs from north to south, about one mile from the western edge of the site. In total, TIAA covers an approximately ten square mile area and includes: the Tucson International Airport; northeastern portions of the Tohono O'Odham Indian Reservation (San Xavier District); residential areas of the Cities of Tucson and South Tucson; and the Air Force Plant #44 Raytheon Missile Systems Company (AFP44). The site is divided into seven separate project areas: Air Force Plant #44/ Raytheon; Tucson Airport Remediation Project (TARP); Texas Instruments (formerly Burr-Brown Corporation); Air National Guard Base; Airport Property; West Plume B and the former West Cap of Arizona Property. AFP44 is located approximately 15 miles south of downtown Tucson, Arizona and encompasses 1,319 acres of land in Pima County. AFP44 lies south and contiguous to the Tucson International Airport. The Tucson International Airport is owned by the City of Tucson and operated by the Tucson Airport Authority. Prior to 1981, groundwater wells within the TIAA site boundaries provided drinking water to more than 47,000 people. SITE HISTORY: At least twenty separate facilities have operated at the TIAA area since 1942 including: aircraft and electronics facilities [which discharged waste liquids directly into the soil]; fire drill training areas [where wastes from training operations were left in unlined pits]; and unlined landfills [which received various wastes from several sources]. Minor sources of soil and groundwater contamination were found at the Burr-Brown Corporation, Arizona Air National Guard Base and the former West-Cap of Arizona facilities. Major sources of contamination were found at AFP44 and at the airport property as described below. Industrial use and disposal of metals, chlorinated solvents and other wastes began in 1942 at facilities located on the western portion of Tucson Airport property. This was followed by large-scale waste disposal at the nearby AFP44 facility during the 1950s. AFP44 is a government-owned, contractor-operated facility. It is operated under contract by Raytheon Missile Systems Company (formerly known as Hughes Missile Systems Company), under the direct supervision and control of Aeronautical Systems Center, Air Force Material Command, at Wright-Patterson Air Force Base in Dayton, Ohio. Its primary mission is weapons systems manufacturing for the Air Force. Hughes and/or its subsidiaries has operated the plant since its construction in 1951 until it was purchased by Raytheon in 1997. In the past, the facility used trichlorethylene (TCE), as a metal degreaser, and chromium in electroplating. Electronic circuit board manufacturing, parts degreasing, and metal plating shops were the primary hazardous waste-generating operations. Hazardous substances generated by plant activities included: spent volatile organic compounds (VOCs) [trichlorethylene (TCE), dichloroethylene (1,1-DCE) and trichloroethane (TCA)], alcohols, methyl ethyl ketone (MEK), and other solvents; used oil and lubricants; waste paint and sludges; and industrial wastewater treatment residue containing metals such as chromium, cadmium and cyanide. Wastewater and spent solvents were discharged into unlined ditches or disposed of in waste pits and ponds. During storm events, surface water runoff from AFP44 property flowed onto the San Xavier Reservation. Beginning in 1976, lined wastewater holding ponds were constructed to receive wastewater discharges. By 1987, thirty-five lined wastewater holding ponds had been constructed to receive process wastewater. In 1997 AFP44 completed upgrading its wastewater treatment system, closed its wastewater ponds and has become a non-discharging plant which recycles 97% of its water. Present industrial operations consist of machining, surface preparation, surface coating, metal plating, and parts assembly of missiles. At the Tucson International Airport property (specifically the Airport Three Hangars Area which was occupied by various defense contractors, including McDonnell Douglas Corporation, Grand Central Corporation and General Dynamics Corporation), chemical use centered around airplane modification and engine part degreasing from 1942 to 1958. During this period, VOCs were used and disposed of on airport property. While TCE was the primary VOC used, other VOCs included methylene chloride, chloroform, carbon tetrachloride and benzene. Nature and Extent of the Problem: Although improper waste disposal at TIAA facilities had stopped by the early 1970s, initial indications of groundwater contamination on the south side of Tucson date back to the early 1950s when elevated levels of chromium were detected in a City of Tucson municipal supply well just west of AFP44. During the same time period, residents just west of the airport property complained that water from private wells had a foul chemical odor. In 1981, EPA and the City of Tucson conducted groundwater sampling and analysis from city municipal water wells within the TIAA. The results of this investigation revealed that there were unsafe levels of TCE contamination in several south-side City water wells. After identifying the Tucson International Airport Area as a Federal Superfund site in 1982, subsequent sampling identified a main plume of groundwater contamination approximately one-half mile wide and five miles in length. A total of 11 City drinking water wells and several more private household wells have been shut down to date as a result of contamination. Additional smaller plumes of contamination at the TIAA include the Arizona Air National Guard, Texas Instruments, West Plume B and the former West Cap of Arizona. These sources are located north and northeast of the airport respectively. Due to poor waste management at these facilities, localized groundwater east of the main contaminant plume is also contaminated.
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