January 15, 2024
By Laurie Hanson
With hanger fires out at the former Marine Corps Air Station (MCAS) Tustin, the U.S. Navy’s ground-water cleanup of carcinogenic contaminants continues and is likely for many years to come.
According to Navy subject matter experts, the Navy has known that certain PFAS are present in ground-water associated with former MCAS Tustin for over 6 ½ years.
Currently, the Navy is investigating the nature and extent of the cancer-causing chemicals and their impact on the soil and ground-water associated with the military base. The Navy is gathering information to help determine what additional actions besides continuing to operate the existing ground-water treatment systems may be necessary.
Peer-reviewed scientific studies have shown that exposure to certain levels of PFAS may lead to Increased risk of some cancers, including prostate, kidney, and testicular cancers.
“PFAS or Per- and polyfluoroalkyl substances are a group of thousands of manmade chemicals that are used in several industrial processes and firefighting activities and to make products non-stick and/or resistant to water, oil, and stains,” said Orange County Water District Chief Hydrogeologist Roy Herndon, what has worked for OCWD for 35 years. “Produced by chemical manufacturers, these substances have been detected in the Orange County Ground-water Basin, which supplies 85 percent of the drinking water supply to north and central Orange County.”
“OCWD and its water retailers are proactively and swiftly addressing PFAS in Orange County,” he added.
“Industrial chemicals have impacted an area in the North Basin (near Fullerton, Anaheim, and Placentia) and the South Basin (near Santa Ana, Tustin, and Irvine) of the Orange County Ground-water Basin that supplies two-thirds of the drinking water for more than 2.5 million people in north and central Orange County,” Herndon explained. “Plumes created by past manufacturing are spreading and threaten to impact the basin. Five water wells have already been removed from service.”
“The Orange County Water District (OCWD) is seeking ways to clean up the pollution in a united effort with local and national regulatory agencies,” he added. “The initial cleanup efforts are focused on cutting off and preventing the spread of contamination before it travels further into the main aquifer supplying hundreds of potable supply wells.”
The Navy began investigating chemical releases at the former Marine Corps Air Station (MCAS) Tustin in the 1980s; when it was closed in 1999, the Navy began investigating potential impacts to ground-water. Soil and ground-water cleanup began in the mid-2000s, according to Hernon.
“In recent years, the Navy began investigating per- and poly-fluorinated alkyl substances (PFAS) at facilities throughout the nation, including former MCAS Tustin,” explained Herndon. “PFAS have been found at the former Tustin base in soil and shallow ground-water, and investigations by the Navy are continuing to delineate the extent of the contamination in the subsurface.”
“Primary chemicals found include chlorinated volatile organic compounds (VOCs) such as TCE and 1,2,3-TCP,” he added. “The VOC contamination was found in shallow soil and ground-water at depths generally within the upper 100 feet below the ground surface – well above the aquifers tapped by drinking water wells.”
“The VOC contamination has not migrated beyond the boundary of the former base,” said Herndon.
After determining in 2016 that no drinking water wells were present within three miles “downgradient” of the former MCAS Tustin, the Navy voluntarily initiated ground-water investigations for PFAS in 2017. According to Navy experts, they also determined at that time that its existing ground-water treatment systems in specific locations within former MCAS Tustin were already effectively removing certain PFAS.
“However, before initiating permanent cleanup operations, it must first be determined what the extent of the lateral and vertical ground-water impacts are,” said Navy experts. “This is currently underway as part of a remedial investigation.
Because of the emergence of PFAS and associated potential health risks, the Orange County Water District (OCWD) and local water supply agencies, including the city of Tustin and Irvine Ranch Water District (IRWD), are addressing PFAS in ground-water by installing treatment facilities at impacted wells. Impacted wells have been shut down until the treatment facilities have been constructed and operational, according to Herndon. More information on PFAS, including a PFAS fact sheet, can be found at the OCWD PFAS information webpage.
The Orange County Water District (OCWD) ensures the water it provides meets or exceeds state and federal drinking water standards. It implements a proactive ground-water monitoring and surface water program to protect the quality of the Orange County Ground-water Basin, which it manages.
The City of Tustin and Irvine Ranch Water District (IRWD) are the two water suppliers for Tustin. The area beneath the former Tustin base is primarily served by the IRWD.
“Sources that supply the City’s water supply are a blend of local ground-water wells and imported water connections originating from Northern California and the Colorado River by MWDSC via the Municipal Water District of Orange County (MWDOC),” explained Herndon.
Irvine Ranch Water District (IRWD) serves about half of Tustin, primarily the city’s southern half, including the neighborhoods surrounding the hangars. They provide water for almost half a million residents in 181 square miles of central Orange County. The City of Tustin Water Services Division serves the other half of Tustin.
“Eighty-five percent of IRWD’s drinking water is ground-water piped in from local wells hundreds of feet below the ground and outside the base area,” said IRWD Public Information Officer John Fabris, who has been with the IRWD for six years. “Most of the rest is imported from Northern California or the Colorado River, and a small percentage comes from Irvine Lake.”
“It’s important to understand that Irvine Ranch Water District (IRWD) water is safe,” he added. “We test the water served throughout our service area daily to ensure it is safe, meeting all quality drinking water standards. We also conduct tests to ensure no detectable PFAS in any drinking water served to our customers. Our Tustin customers are served water piped in from sources outside the area of the base.”
“IRWD treats and tests its water to ensure it is safe to drink,” said Fabris. “Each day, IRWD scientists collect samples from neighborhoods throughout the district to ensure our customers get the highest quality drinking water. Using advanced technologies in our laboratory, they screen the water and report more than 100,000 analytical results a year.”
“In addition, our imported water is tested by the Metropolitan Water District of Southern California (which imports the water), and our ground-water is tested by the Orange County Water District (OCWD) (which manages the Orange County Ground-water Basin),” he explained.
As part of the Navy’s current treatment operations, ground-water is extracted and pumped through vessels containing granular activated carbon (GAC), similar to what is found in refrigerators, pitchers, and whole-house water filters. The GAC absorbs PFAS from the ground-water. The treated ground-water effluent is discharged under permit to the sanitary sewer. The “spent” GAC is either regenerated for reuse or disposed of appropriately.
According to Navy experts, “Ground-water treatment systems have been operating since late 2007 to early 2008 to address certain volatile organic compounds such as trichloroethene and 1,2,3-trichloropropane. For the most part, the Navy manages its qualified contractors to complete the work.
Current modeling and professional estimates suggest ground-water treatment will be completed in approximately two decades.
The Navy’s experts emphasized that no ground-water within three miles downgradient of former MCAS Tustin is being extracted for drinking water supply. They said that by law, residents are provided with information regarding their drinking water quality from the purveyors. The Navy has provided notices to the city of Tustin and local Homeowners Associations regarding its efforts to investigate and remediate PFAS in ground-water.
“For many years, the Navy has been in close communication with the city of Tustin and Orange County Water District regarding ground-water cleanup efforts,” Navy experts said. “Semiannual Restoration Advisory Board meetings are conducted at the Tustin Area Senior Center and are open to the public. The next one is scheduled for April 10, 2024.