TUCSON INTERNATIONAL AIRPORT AREA

This administrative record file contains the documents that the U.S. Environmental Protection Agency (EPA) has used and is currently using to identify appropriate response activities for the Tucson International Airport Area Superfund Site, Area A & Area B Groundwater Operable Unit in Tucson, Arizona. It is presented in two media: microfilm (original compilation and supplements 1-6) and the Compact Disk (supplement 7).

The documents contained in the original index and Supplements 1 and 2 of the administrative record were used by the U.S. Environmental Protection Agency (EPA) to identify and select the cleanup requirements in EPA’s Record of Decision (ROD), dated August, 1988. EPA’s 1988 ROD addresses groundwater contamination (primarily trichloroethylene, or TCE) in what is referred to as Areas A and B of the regional aquifer located north of Los Reales Road at the Tucson International Airport Area Superfund Site in Tucson, Arizona.

Supplements to the administrative record file were added as documents related to remedy selection became available. (Note: Documents AR 56, AR 69 and AR 183.3 were removed from the original compilation, because they were determined either to be duplicates or not pertinent to this administrative record). The original compilation and all supplements are arranged in ascending chronological order. All supplements, with the exception of supplement 6, have undated documents at the end of each sequence.

The administrative record file was microfilmed in September 1994. At that time the index was edited to conform more closely with current Region 9 standards, and the title was made more specific (“Area A & Area B Groundwater Operable Unit”). Two essential documents were added to the file as Supplement 3: AR 1, which is the August 1988 ROD, and AR 2, which is comprised of the list of guidance documents considered or relied upon in the selection of the remedy.

Supplements 4-6 to this administrative record were microfilmed in August 2002. Supplement 4 consists of documents added to the administrative record that were relied upon or considered as part of EPA’s “Explanation of Significant Differences” (ESD 1). ESD 1 modifies the 1988 ROD’s groundwater remedy for Area B-west (Air National Guard Base project area). At the end of the public comment period for ESD 1, the final ESD and supporting documents used by EPA were added to this administrative record as Supplement 5, dated March 14, 1997.

Supplement 6 to this administrative record contains documents added to the administrative record that were relied upon or considered for EPA’s proposed “ROD Amendment,” as described in EPA’s Proposed Plan, dated June 2002. The proposed “ROD Amendment” identifies contamination in Area B of the Site (West-Cap and West Plume B) and proposes the remedy to address this contamination. The list of EPA guidance documents which were considered or relied upon in the proposed “ROD Amendment” is document AR 65 of Supplement 6 in this administrative record file. Copies of the guidance documents are contained in the Compendium of CERCLA Response Selection Guidance Documents located in the Region 9 Superfund Records Center. Comments on and responses to the Proposed Plan, the ROD Amendment itself, and other documents added to the administrative record that were relied upon or considered as part of the ROD Amendment are contained in supplement 7 to this administrative record file.