The Dover Air Force Base is moving toward a long term solution for off-base drinking water wells contaminated with a class of industrial chemicals known as PFAS.
In July, four private drinking water wells northwest of the Dover Air Force Base were found to contain levels of PFOS and PFOA, two per- and polyfluoroalkyl substances (PFAS), up to 2,400 times the federal lifetime health advisory level.
The five businesses, two residences and one office building served by the four contaminated wells have been provided bottled water by the Dover Air Force Base (DAFB). But 436th Airlift Wing spokesman Technical Sergeant Charles Broadway says DAFB plans to install water filtration systems on the properties by the end of the year.
The City of Dover is also working with the Air Force to eventually connect the properties to municipal water.
“Well we think it’s in the best interest of public safety to support this overall goal,” said City of Dover Public Works Director Sharon Duca.
Duca says City Council must approve annexation of the properties for municipal water service, and that the city will not subsidize the cost of the connection.
“One of the biggest things that’s involved here is the crossing of Route 113, because that’s not a simple feat to get across that expanse of highway,” said Duca. She adds DAFB will lead the design.
“Our first priority is protecting drinking water sources because drinking water is a direct pathway to human consumption,” said Broadway in an email.
PFOS and PFOA were present in firefighting foam previously used at the Dover Air Force Base. PFAS chemicals have been linked to an increased risk of cancer and other health problems.
The four contaminated wells were among roughly 30 tested in June in the first phase of an “expanded site inspection” near two historic PFOS and PFOA release areas on the DAFB.
Nine additional wells were tested in August, and owners were notified once results were validated in September. These tests revealed combined PFOS and PFOA concentrations between 0 and 69 parts per trillion (ppt), according to DAFB officials. The EPA’s unenforceable lifetime health advisory for the substances is 70 ppt. DAFB officials say the well containing 69 ppt is on the same property as one of the four contaminated wells.
Broadway says the Air Force will continue investigating the contamination under the federal Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as Superfund. He says the first two steps outlined in CERCLA— preliminary assessment and site inspection— have been completed. He says “remedial investigation will evaluate any possible migration pathways and potential health impacts," during the third phase of the CERCLA process.
This summer, Sen. Tom Carper, Sen. Chris Coons and Congresswoman Lisa Blunt-Rochester sent a letter to the U.S. Secretary of Defense requesting more information about the PFAS contamination near the Dover Air Force Base — including groundwater testing results and a map of contaminated wells.
The letter also asked for a remediation plan and a feasibility assessment for putting the affected properties on municipal water.
The Air Force has been responding to contamination of drinking water supplies at Dover Air Force Base with PFOS and PFOA since 2014. In 2016, the Department of Defense found levels of the chemicals in the groundwater there up to 2.8 million parts per trillion—40,000 times higher than the EPA health advisory level.
