Cleanup Effort Continues at Former George Air Force Base

The geology, the climate, and the dry ground's sensitivity to water have complicated the cleanup effort at the former George AFB.
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The Air Force has been working to clean up the former George Air Force Base since 1981, spending over $113 million to rid the ground and two aquifers of jet fuel, solvents, and pesticides. And the job isn't finished. The federal government anticipates spending another $59.95 million at George through 2023. The estimate includes labor, maintenance and operations as well as cleanup costs.

Many routine aircraft maintenance tasks performed at George while the base was active (1941-1992) involved potentially hazardous materials such as jet fuel, gasoline, paints, and solvents. Such materials were spilled or leaked into the soil and groundwater, causing contamination.

The potential risk to human health and the environment was significant enough for the U.S. Environmental Protection Agency (EPA) to place George on its National Priorities List (NPL) in February 1990. A 1980 federal law known as CERCLA (Comprehensive Environmental Response, Compensation and Liability Act) - better known as Superfund - requires sites on the NPL to undertake "long-term remedial response actions that permanently and significantly reduce the dangers associated with releases or threats of releases of hazardous substances that are serious, but not immediately life threatening." The Air Force, EPA Region 9, California Dept. of Health Services and the California Regional Water Quality Control Board Lahontan Region (now the Lahontan Water Board) signed a Federal Facility Agreement in October 1990 to outline how they were going to proceed with the cleanup. The Federal Facilities Agreement identified 67 sites for attention, a number which has changed over time.

The Air Force is legally required to pay for the cleanup, which began over a decade before the base closed in 1992. The Air Force contracted with scientists, engineers, and construction teams to do the work.

Cleanup sites at George were divided into five operable units (OUs). A proposed plan for remediation in OUs 1 and 3 was developed, followed by public review and input and formal responses to that input. Records of Decision (RODs) identifying remedial actions were developed and signed for OU1 and OU3, with the EPA acting as the lead agency. Once signed by EPA and the Lahontan Regional Water Quality Control Board, the RODs became binding agreements between the Air Force and the regulatory agencies regarding remediation in each OU. OU2 has petroleum sites being cleaned under Water Board supervision, as so-called "non-CERCLA" sites, with no EPA involvement. OU 4 sites were administratively closed with no further action needed, or moved into OU 5, established in December 2006 to manage five IRP sites, including the former skeet ranges. A ROD for OU 5 is scheduled for completion in 2012.

Much has been accomplished at George, including removal of tons of contaminated soil and more than 80 underground storage tanks, closure of a hazardous waste storage yard, and removal of 493,495 gallons of jet fuel. Skeet ranges have been cleared of lead shot. Some 1,642 pounds (136 gallons) of Trichloroethylene (TCE), used mainly as a solvent for cleaning metal parts, have been removed from soil and groundwater. And more than 2.4 million pounds of what's known as Total Petroleum Hydrocarbons as gasoline (TPH-g) have been removed. Eleven of the 13 munitions-related sites, including three skeet ranges and a grenade training range, have been cleaned up. Two sites still require cleanup, a munitions burial site and a small-arms range.

At numerous former landfills, contamination has been "capped" with native soils and exterior drainage was added to prevent further leaching into the soil or water.
The geology, the climate, and the dry ground's sensitivity to water have complicated the cleanup effort at the former George AFB. Located in the High Desert in rural San Bernardino County, George receives an average of less than six inches of rain a year. In such a dry environment, the plentiful irrigation used at the former base pushed contaminants into the aquifer. Once a pollutant gets into the groundwater, it flows with the water in what's known as a plume, degrading the water's quality. The plumes at George are far beneath the surface and can be monitored only by drilling 130 to 260-foot deep wells. The soil at George is a heterogeneous mix of sand, silt, gravel, clay, hard cobbles and boulders, which complicates drilling.

There are two aquifers under the area, an upper aquifer about 130-140 feet underground, then a layer of sand and clay, then a lower aquifer, which can be up to 200 feet underground. An underground waterfall connects the two aquifers. The city of Victorville's water supply comes from the lower aquifer, also called the regional aquifer, which is upstream of the former base.

In the groundwater, fuel is present as what's called "free product," fuel that floats on the water and dissolves into it. Free product is being removed at George by drilling wells into the contaminated groundwater, inserting pumps with a hydrophobic membrane to filter out the water, then pumping the fuel into tanks above ground. In the tanks, the fuel separates from whatever water and dirt travel with it, then it's pumped out and taken away.

Solvents, such as TCE, also dissolve in water, but are less subject to degradation and attenuation by naturally-occurring soil microbes than fuel is, making solvents harder to clean up than fuel. Removing 232 pounds (19 gallons) of TCE from OU1 required pumping 1.56 billion gallons of water from the aquifer, treating it, then returning the water to the aquifer.

This pump and treat remedy was used on the TCE plume in OU 1 for 12 years, from 1991 until 2003. Numerous monitoring wells are used to measure the size and movement of the plume as well as concentrations of TCE in various locations. The water treatment system was shut down in 2003 due to concerns that it might be causing the plume to expand more rapidly than it would without the pump and treat remedy. Monitoring continues while a feasibility study is underway to identify an optimized remedy for the OU1 plume. A proposed plan will be scrutinized by regulators and the public. Public input will be part of the process, which might lead to a ROD amendment.

Within the past six years, a massive fuel plume, containing about 3.5 million gallons of jet fuel, was discovered about 160 feet under what's called a "tank farm," a group of aboveground fuel storage tanks, each holding thousands of gallons of fuel. Some of the tanks are still being used by businesses flying at the site, now known as Southern California Logistics Airport. The Air Force installed 22 new monitoring wells in 2010 to get more data on the extent of the plume.

Pollutants at George include Dieldrin, a pesticide once used for termite control at base housing. When the base was operational, a lot of irrigation was being used, pushing contaminants like Dieldrin into the aquifer, where it has become another plume. The compound is slightly soluble in water. Proposed remedial action will be described in a Pesticide Corrective Action Plan, which, as of late 2011, had been submitted to regulators for comments.

In the soil above the groundwater, both fuel and TCE are present as vapor. Soil vapor extraction (SVE) is used to remove them. Extraction wells are drilled, then the air is sucked out, pulling fumes from tiny pore spaces between grains of sand. Once extracted, the fumes are released to the air, destroyed, or filtered through granular activated carbon. SVE is used near sources of pollution, such as a former burn pit and a former aircraft maintenance hangar, to remove contaminants before they get into the groundwater.

The cleanup will continue until it's finished. Ongoing cleanup activities have little effect on redeveloping the property. No water from under the former base is used as drinking water. The City of Victorville, currently the former base's water purveyor, draws water upstream of the former base. Institutional controls restrict access to certain parts of the base and prevent tampering with cleanup systems.

Portions of the former base, including the tank farm, portions of the flight line, and the housing area, were removed from the Federal Facilities Agreement by the EPA in 2005, transferring authority for monitoring cleanup to the Lahontan Water Board. Corrective Action Plans for these sites, developed by the Air Force Real Property Agency, have been submitted to the Water Board for approval.

Two pieces of land from the former air base have yet to be transferred by the Air Force into other ownership.

Ironically, even as the Air Force Civil Engineer Center works to convey former Air Force base property to other owners, the Air Force has had to buy land adjacent to the former base as part of the cleanup effort. Since George closed, the Air Force has acquired another 77 acres of nearby property needed to drill monitoring wells so scientists could track plumes. This unexpected purchase is emblematic of the continuing challenges -- and the ongoing need for problem-solving - faced by those dealing with environmental restoration at George and other closed Air Force facilities.