Noisy pumps draw water through four tall, white tanks outside a water treatment plant in suburban New Castle. The summer heat forms condensation on the outside of the tanks because the water comes from deep underground.
The tanks contain carbon filters that remove a group of toxic chemicals from the groundwater, in order to make it drinkable.
“Prior to any of this, the water would have just come into the treatment plant and then been hit with the chemicals, and then went out,” says Kenny Haggerty, the supervisor of water quality at Artesian, which owns the plant. “But now this has to go through the treatment out here.”
It’s been seven years since Artesian and the City of New Castle’s water utility shut down and installed filters on drinking water wells near the Delaware Air National Guard Base after finding them contaminated withPer- and Polyfluoroalkyl Substances—more commonly known as PFAS. But the state still doesn’t know for sure the source or extent of the groundwater contamination there.
PFAS are man-made chemicals long used in consumer products from food wrappers to carpets. They’re ubiquitous—popping up in groundwater and drinking water supplies across the country—but they’re not well understood.The CDC says some studies in humans suggest high levels of certain PFAS may increase cholesterol levels, increase the risk of pregnancy complications, affect the immune system and increase the risk of some cancers.
Artesian and the City of New Castle found PFAS in some of their drinking water wells in 2014—above a provisional health advisory from the EPA. They took these wells offline and installed carbon filtration systems before starting them up again.
According to the CDC, the City of New Castle actually found evidence of PFAS in wells as early as 2009, but lab results were inconsistent, and the utility was told to monitor the issue at five-year intervals.
Artesian removed its last contaminated well from service in 2016. But the chemicals can stay in people’s bodies for years.
An ongoing study by the CDC of PFAS exposure through drinking water at eight sites nationwide found as of 2019, New Castle-area residents had three different PFAS chemicals in their blood at levelsseveral times the national average.
State officials say the water Artesian and the City of New Castle provide is currently safe to drink in regards to PFAS.
“Our goal is to remove it to non-detect levels,” said Virginia Eisenbrey, director of customer relations and operations supply at Artesian, in an interview earlier this month. Eisenbrey says Artesian tests the filters monthly and replaces them when one of the PFAS chemicals starts to “break through.”
The Municipal Services Commission of the City of New Castle tests its treated water for PFAS every six months, and also aims to treat it down to non-detect levels, according to Water Utility Manager Jay Guyer.
PFAS contamination above the EPA’s provisional health advisory level was originally reported in five public drinking water wells near New Castle in 2014. But a consultant report to state environmental regulators this spring showed the untreated water in 11 wells exceeded the EPA’s current advisory level as of 2019.
Concentrations of combined PFOA and PFOS in these wells ranged from 71 parts per trillion (ppt) to 4,500 ppt, compared to the EPA’s health advisory level of 70 ppt.
Still, the City of New Castle and Artesian say they have not had to add any new filters or otherwise change their response due to changing contamination.
“Nope,” Eisenbrey said. “We took things offline immediately. We've been treating ever since.”
But monitoring and cleanup of the release is not resolved.
DNREC Division of Waste and Hazardous Substances Director Tim Ratsep says the state does not know how widespread the PFAS groundwater contamination is near New Castle—or whether it’s growing.
“So in 2014, we didn't know exactly the extent of the plume, and that's why we're continuing to find out where it is,” Ratsep said. “So where we're finding it now, it could have been present there in 2014. We just don't know because we didn't look in 2014 to see if it was present.”
Ratsep adds that varying test results are not surprising, because of the “mobility” of PFAS in groundwater and factors such as rainfall. He says new monitoring wells are still being installed. Holding the sources of contamination accountable
One reason to keep studying the site is to find out where the PFAS, which is found in foam used to put out fuel fires, came from.
“Right now, the Delaware Air National Guard and the [New Castle] airport itself are potential responsible parties, because of the history that we know of their past operations,” Ratsep said. “Can we confirm right now that they are truly the responsible ones for this plume? We cannot.”
The Department of Defense (DOD) is investigating potential PFAS releases at bases across the country. It formed a PFAS Task Force in 2019 and last year identified 108 installations that “may have used or potentially released PFAS.”
DOD says it no longer uses PFAS-containing firefighting foams for testing or training at its installations, but it still uses it for emergency responses, because PFAS-free alternatives do not meet the military’s safety standards. DOD says it is “actively seeking an alternative,” and treats each use of PFAS-containing foam as a “spill response.”
DOD officials did not accommodate a request for an interview about the PFAS contamination in New Castle.
Jim Salmon, a spokesperson for the Delaware River and Bay Authority, which has managed the New Castle airport since 1995, said in an emailed statement that the Federal Aviation Administration currently requires certain airports such as the New Castle airport to use firefighting foams containing PFAS.
“While the Delaware River and Bay Authority has not discharged any PFAS-containing foam, it is aware of the historical use of PFAS at the New Castle Airport,” Salmon wrote. “DRBA will work cooperatively with DNREC and other government entities as necessary and appropriate to address concerns of potential PFAS contamination.”
When the parties responsible for the PFAS contamination of groundwater near New Castle are identified, they’ll be on the hook for cleanup. DNREC’s Ratsep says this could mean a settlement agreement to investigate the site and remediate it. Currently, the best solution is filtering the PFAS out of drinking water at the point of treatment—so finding responsible parties could also mean paying back the water utilities that filter the PFAS out.
“Right now our customers are paying for it,” Artesian’s Eisenbrey said. “Hopefully one day they'll be made whole for the cost of the treatment.”
Costs of PFAS treatment are also passed to City of New Castle customers, in the form of higher rates. The initial carbon filtration system cost the City $1.3 million, but close to half of it was covered by a USDA Emergency Grant. The City has budgeted around $60,000 for operation and maintenance of the system in the coming fiscal year. Guyer, New Castle’s water utility manager, says the City would look at options for seeking compensation for these operational costs if a responsible party were identified. PFAS testing and treatment could become mandatory
Eisenbrey says Artesian currently tests for and filters out PFAS not because it's required to, but because the company believes “it’s the right thing to do.”
“I think there's probably a regulatory lag,” she added.
Many public water utilities in Delaware are not currently required to proactively test for PFAS, because the chemicals are not regulated under the federal Safe Drinking Water Act.
The EPA has set an unenforceable health advisory level for two PFAS chemicals: PFOS and PFOA. Delaware uses this as a cleanup standard for drinking water under its Hazardous Substance Cleanup Act—but only at facilities where hazardous substances have already been found, and identified as a risk to human health and the environment.
Artesian first found PFAS in some of its wells in 2014 because of a federal program that requires public water systems over a certain size to test for a list of unregulated contaminants every five years. This list included PFAS for the first time in 2013-2015, so it’s not known how long New Castle-area customers were exposed to PFAS before then.
Whether public drinking water in Delaware that exceeds the EPA’s health advisory for PFAS is required to be treated is also “kind of a gray area,” says Jamie Mack, environmental health director at the state Division of Public Health.
“If a company notices an issue or DPH recognizes an issue, then we would hope that they would voluntarily comply and take the steps necessary to make the correction,” Mack said. “But if we have resistance, or a utility is less than enthusiastic about partnering with us to take the necessary actions, then we could step in with public health authority or with DNREC authority to require it.”
But this ambiguity could soon end, thanks to a billthat passed the General Assembly earlier this month and awaits the Governor’s signature.
House Bill 8 requires the state environmental and health agencies to develop an enforceable drinking water standard—called a maximum contaminant level, or MCL—for PFOS and PFOA. That would mean public water systems proactively testing for the contaminants, and treating any water that exceeds the MCL.
“That's one of the advantages of having the MCL, it's crystal clear,” said Gerald Kauffman, director of the University of Delaware’s Water Resources Center. “You have to test it and regulate it. And if it's higher than the MCL, the substance—PFAS— then has to be treated .”
House Bill 8 is sponsored by state Rep. Debra Heffernan (D-Bellefonte), an environmental toxicologist who has served on the state’s Hazardous Substances Cleanup Act Advisory Committee. In addition to directing DNREC and the Division of Public Health to develop an MCL, the legislation mandates a statewide “survey” of PFAS in drinking water. DNREC would need to provide results of this survey and a “specific plan” for addressing any PFAS contamination it identifies to the Governor and General Assembly by January 1, 2022.
Kauffman notes even if the federal government sets standards for PFAS chemicals, like some expect it to do, the state could set lower ones. New Jersey has already done this, with MCLs for PFOS and PFOA at 13 and 14 ppt respectively—roughly ? of the EPA’s current advisory level.
“If we have an MCL for these substances in Delaware and EPA, nationally, this will avoid big time problems in the future," he said. "Because these substances will be detected early at levels even below the drinking water level, where you can then take action.”
This early detection and action could reduce the risk of repeating the PFAS exposure in New Castle elsewhere in the state.
“That's what MCLs do—they catch the problems early,” Kauffman said.
