The 3,452-acre McClellan Air Force Base (Ground Water Contamination) site was established in 1936 and operated as an Air Force Logistics Command Base until 2001. Its primary mission included management, maintenance and repair of aircraft, electronics and communication equipment. The operation and maintenance of aircraft have involved the use, storage and disposal of hazardous materials, including industrial solvents, caustic cleansers, paints, metal plating wastes, low-level radioactive wastes and a variety of fuel oils and lubricants. The Air Force has identified 326 waste areas of known and suspected contamination. The site’s long-term cleanup is ongoing.
The primary contaminants in groundwater are volatile organic compounds (VOCs). Contaminants detected in soil include PCBs, heavy metals, and several non-VOCs. Radionuclides have also been identified in surface soil and in former disposal pits. People may face a health risk if they accidentally ingest or come into direct contact with contaminants. People also may be at risk if they eat foods containing accumulated contaminants or if they inhale contaminated dust or soil vapors. Risks to wildlife and their habitat may occur on and adjacent to the former Base in some areas of the creeks, vernal pools, and other parts of the flood plain.
This site is being addressed primarily through federal actions directed by the Air Force Real Property Agency (formerly known as the Air Force Force Base Conversion Agency) and overseen by US EPA Region 9, California State Department of Toxic Substances Control (DTSC), and California Regional Water Quality Control Board (RWQCB). The Air Force, EPA, and State work together under the terms of a Federal Facilities Agreement (FFA) signed in 1990.
As part of the “Privatized” Cleanup Approach (see below), the 1990 FFA has been amended 3 times (2007, 2009 and 2011) to allow McClellan Business Park LLC (MBP) to assume responsibility for cleanup of 1190 acres of McClellan AFB. MBP conducts the cleanup actions under the oversight of EPA, DTSC and RWQCB, as with other areas of McClellan AFB. The FFA Amendments further provide that EPA in consultation with the State regulators will select the response actions for the privatized parcels and that if MBP should fail to perform their cleanup responsibilities, the Air Force will resume their responsibilities under the original 1990 FFA.
The McClellan Privatization was selected as a pilot demonstration project under EPA’s Superfund Integrated Cleanup Initiative, a national effort to identify and implement improvements to the Agency’s land cleanup programs. http://www.epa.gov/oswer/integratedcleanup.htm
Groundwater extraction and treatment continues at the former Base. Groundwater is extracted and treated at the groundwater treatment plant (GWTP) in the central portion of the facility. With the installation of the Phase 3 on-base groundwater extraction wells in September 2005, the extraction network was essentially complete. Currently, 1500 gallons per minute (gpm) of extracted groundwater are treated (via air stripping and ion exchange) before being discharged to Magpie Creek. Ongoing operation and maintenance activities continue. Since Phase 3, several extraction and monitoring wells have been replaced and new monitoring wells were installed in the southern area of the base to delineate a previously undefined carbon tetrachloride plume. Groundwater cleanup is expected to continue for several decades until cleanup is attained. The Fate, Flow and Transport Model that was developed in 2004 predicted that TCE could be below its maximum contaminant level (MCL, 5 ug/L) in 55 years. That model is currently (2012) being updated with recent information and recalibrated. Plans for aggressive hot spot remediation are underway which is estimated to reduce the cleanup time by 17 years.
SVE is a component of the VOC groundwater remedy. SVE is used to remove and treat VOC sources in the vadose zone with the potential to migrate to groundwater. A large majority of the 1.6 million pounds of solvents removed to date from the groundwater and soil have been extracted by these SVE systems. Of the 26 areas (plumes) originally identified for SVE, only 10 are still active. Additional systems may be added to complete the network that protects groundwater from VOCs in the vadose zone if they are needed.
*Note – We’ve posted, verbatim, the information from the EPA on McClellan on this page rather than simply sharing a link. This is to maintain an ongoing record of the information to-date as of October 2015, in the event it is edited or removed from their site in the future.
For a complete look at groundwater contamination at McClellan, visit this EPA link: McClellan Air Force Base – EPA Superfund site
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