Board tours cleanup sites Published Oct. 30, 2015 By Merrie Schilter-Lowe 60th Air Mobility Wing Public Affairs TRAVIS AIR FORCE BASE, Calif. -- Dave Marianno has been a member of the Travis Air Force Base, California, environmental restoration advisory board since its creation in 1994. He faithfully attends RAB meetings and has visited the base numerous times. What Marianno hadn't seen, until Friday, were some of the new technologies the base's environmental restoration support staff employs to clean up groundwater contaminated with trichloroethene, or TCE, which is a solvent. "It's a lot different from when we started," said the 81-year-old Marianno as he gazed at a bioreactor while the restoration team explained its operation. The bioreactor, located west of the air traffic control tower, is being used to treat a 210-acre TCE plume that runs beneath the aircraft parking ramp and taxiway. It was the third stop on the orientation tour for current and new RAB members. "This used to be a degreasing facility," said Lonnie Duke, restoration team environmental scientist who was referring to the building next to the bioreactor. Duke said that in the past, aircraft workers used TCE to degrease metal and aircraft parts. They spilled or dumped used solvent on the ground or into a drain where it migrated down into the soil and groundwater. The bioreactor is one of three bioremediation technologies the restoration team is using that employs micro-organisms to metabolize and remove pollutants from the soil and groundwater. Primarily, a bioreactor is a hole in the ground that has been backfilled with organic mulch and gravel. The system acts like an underground coffee percolator, promoting the growth of solvent-eating microbes that breakdown TCE into harmless substances. The restoration team has cleaned up or set up permanent restrictions for all of the contaminated soil sites on base. However, they are still working on 15 groundwater sites contaminated with TCE. The U.S Environmental Protection Agency banned the solvent years ago as a possible carcinogen. None of the groundwater on base is used or consumed by humans or animals. However, it does flow into Union Creek and potentially could migrate to the Suisun Marsh, said Glenn Anderson, hydrologist on the restoration team. TCE is heavier than water so it moves slowly through the subsurface, forming a pool or plume. The restoration team is trying to break down the solvents in those plumes before they flow toward the creek. Marianno, who has served as the RAB community co-chair since 2005, said he understands how past practices contributed to soil and groundwater contamination problems today. "We didn't know (dumping solvents on the ground) would be a problem back then," he said. "We were fighting a war and needed to keep the planes flying. We needed to get the job done." The Department of Defense established the environmental restoration program in 1975 to provide guidance and funding to investigate and remediate hazardous wastes sites caused by past disposal practices at military installations. In 1989, the level of contamination at Travis placed the base on the EPA's National Priorities List. EPA has primary responsibility to protect human health and the environment by writing and enforcing environmental laws and regulations. The restoration program team manages environmental cleanup efforts at Travis with input from the EPA, Department of Toxic Substances Control and the San Francisco Bay Regional Water Quality Control Board. The team also receives input from the restoration advisory board and other public forums. "The RAB provides a forum for the base, community and regulatory agencies to discuss and exchange information about the restoration program and review and comment on plans and reports," said Mark Smith, environmental restoration program manager. The Travis restoration program is mature and has been active in cleanup for more than 32 years. "As such, we are reaching the point where all cleanup remedies will be in place, many sites will have achieved clean closure and other sites will pose a reduced risk as the levels of chemicals of concern have diminished," Smith said in a letter welcoming the nine new RAB members. During the tour, Smith talked about some of the history and the status of several cleanup sites on base. "We're using solar power to run the pumps," he said while pointing out a former landfill area where groundwater extraction pumps are in use. Before bioremediation, groundwater extraction techniques - commonly called pump and treat - were the primary means of cleaning up contaminated sites on base. These systems use vacuum-enhanced pumps to extract millions of gallons of groundwater from the subsurface for treatment and then discharges the water into Union Creek. Pump and treat works well when contamination levels in groundwater are at a high concentration, Anderson said. But over time, the contamination levels decrease while the cost of operating the pumps increases, he said. The solar-powered pump is green, sustainable and does not use electricity from the base's power grid. To avoid the cost of building, operating and maintaining extensive pump-and-treat systems, the restoration team looked at other remediation technologies, including phytoremediation, which involves planting red-bark eucalyptus trees to remove a solvent plume downgradient of a bioreactor and installing a biobarrier, which involves injecting emulsified vegetable oil into a row of injections wells to intercept and degrade the TCE plume. Both technologies are working well, according to the restoration team. "We needed a better means of getting to the last bit of solvents," Duke told the group at the site of an EVO demonstration project on base. He said the biodegradable, milky looking substance is injected into the subsurface under water pressure, creating an ideal environment for micro-organisms that "eat" the oil. This reduces the oxygen levels in the groundwater, creating the right conditions for a second class of micro-organisms to break down the solvents. "There's so much going on here that we never knew about," said Thomas Randall, one of the new RAB members. As a former honorary commander and a current Air Mobility Command civic leader, Randall said he thought he had a good grasp of the activities on base. "This was an eye-opener," he said of the tour. The next RAB meeting is at 7 p.m. Nov. 5 in the Northern Solano County Association of Realtors Office located at 3690 Hilborn Street in Fairfield, California, Smith said. The public is invited to attend the meeting.