As the oldest operational Air Force base on the west coast, personnel at March engaged in a wide variety of operations dealing with toxic and hazardous substances as early as 1918. Hazardous wastes were generated primarily from industrial operations such as aircraft cleaning and vehicle maintenance, fire protection training, and fuels storage and use. The base closed in 1996, although 2,169 acres were retained by the Department of Defense for use as March Air Reserve Base.
Historically, wastes were disposed of using incinerators, discharging them into sanitary sewer systems and storm drains, and placing them in unlined pits and landfills. Accidental spills of fuels and chemicals such as cleaning solvents also occurred.
The environmental cleanup program at March began in 1983. A thorough search of base records, analysis of aerial photographs, and interviews with current and former base employees identified 28 sites of likely contamination requiring further evaluation. Collection and analysis of soil and water samples determined which contaminants were present. These further studies turned up more sites, bringing the total to 44. These sites were numbered and grouped into three operable units (OUs).
Groundwater was contaminated with volatile organic compounds and jet fuel. All contaminated wells on and off the base were closed down by the Air Force in 1988. The Air Force supplied bottled drinking water to off-base residents until they were connected to a public water system. People on base were connected to the Eastern Water District system.
In November 1989, March was placed on the U.S. EPA's National Priorities List, a list of sites that are considered to be of special interest and require immediate attention. In September, 1990, a Federal Facility Agreement (FFA) was signed by the Air Force, which is the lead agency in the cleanup, and three regulatory agencies: the U S. EPA, the Department of Health Services (now Cal/EPA DTSC), and the California Regional Water Quality Control Board (CRWQCB), Santa Ana Region, which is a part of Cal/EPA. The FFA provides a kind of blueprint for cleanup activities.
Summary of Cleanup Status, and What's Left to be Done
Of the original 44 sites, 31 have been completely cleaned or recommended for No Further Action.
The soil was contaminated with volatile organic compounds and heavy metals. By 1992, the Air Force had removed all leaking underground storage tanks and approximately haIf a million cubic yards of contaminated soil. About 10,000 cubic yards of contaminated soil have been cleaned and replaced.
Landfills contained materials such as construction debris and household waste. Cleanup actions included removing landfill contents or placing it in sealed cells.
Over 250 million gallons of contaminated water have been cleaned since 1992, when a groundwater interception and treatment system was put into operation. Ten million gallons of water are cleaned each month by the expanded system, also known as EGETS.
The last remedy was in put in place at the former March AFB in 2008. None of the cleanup sites currently pose a threat to human health or the environment in the surrounding communities.
All contamination is contained within the former base, with the exception of a low-level plume of trichloroethene (TCE) that has migrated into the groundwater off the eastern boundary. The groundwater in this area is not used for drinking, and the aquifers are deep underground with no pathway for exposure to the outside environment, so the plume is not a hazard to area residents and does not restrict land use (except to prohibit the installation of drinking water wells). March has been treating this plume and its source area since 1992, with a resulting decrease in the size and concentration of the plume.
Environmental Cleanup Award Winner
March aggressively implemented its Installation Restoration Program, making it a leader in the Department of Defense's program to clean up contamination on military installations. In 1993, March won the Environmental Restoration Award for the best IRP in the Air Force, and March was nominated again for the award for 1997.
One of March's proposals, which was agreed upon by the regulators, was to complete only enough of the eight required CERCLA studies to determine the nature of a problem, then put a remedy in place while continuing the studies. These remedies, titled Interim Removal Actions, range from complete removal of contaminated soil to installing pilot treatment plants for in-place soil and groundwater cleanup. Another innovation was overlapping the administrative review of key cleanup documents, reducing the overall review time by up to 75%.
Bioremediation Pilot Study
Recent investigations and groundwater monitoring identified hot spots within OU2. At two of these sites --Site 8 Buildings 355/373 and Site 36 --previous remedial measures of soil vapor extraction and groundwater treatment had proven to be only partly effective at reducing contaminant mass. In addition, the area's rising groundwater levels impeded application of vadose zone (the unsaturated area between the earth's surface and the water table) remedies at these sites.
A pilot study completed in 2011 and published in 2012 concluded that enhanced in situ bioremediation, injecting materials into the ground to promote bacterial degradation of the pollutants, was effective and efficient as a remedial option. Additional injections at the site might prove beneficial, according to the report, and cleanup times have been proven to be reduced.