Fairfax Water: PFAS found upstream of Occoquan; utility warns of roughly $389 million treatment bill and urges source controls

Fairfax Water General Manager Jamie Hedges told the Environmental Committee on Oct. 29 that the utility's monitoring has identified PFOA and PFOS at levels that will prevent the Occoquan source from meeting the Environmental Protection Agency's forthcoming PFAS drinking-water standard without new treatment.

Hedges said the utility’s sampling program—conducted monthly with the Occoquan Watershed Monitoring Lab at Virginia Tech—has found PFOA and PFOS above the regulatory limit at several tributary sites, including Bull Run, Cub Run and Broad Run, and that PFOA readings are about 1.5 parts per trillion above the new limit while PFOS is just under the limit. "PFAS have been called forever chemicals because they do not break down readily in the environment," Hedges said, noting the compounds move easily through the water cycle.

Why it matters: Fairfax Water serves roughly 2 million people regionally and draws about 40% of its treated water from the Occoquan Reservoir. Hedges warned that complying with EPA's rule will require large treatment facilities. "The capital required to comply with the regulation is estimated at nearly $389,000,000," she said, adding that operating costs will be substantial because removal media must be replaced multiple times per year and that disposal is expected to become more difficult after PFOA and PFOS were designated hazardous substances under CERCLA.

What Fairfax Water will do: The utility plans a year-long pilot test of granulated activated carbon filtration (GAC) and ion-exchange systems to assess performance across variable source-water quality at the Occoquan. Hedges emphasized none of the candidate technologies destroy PFAS; they separate them into another waste stream, creating residuals that require careful handling.

Source identification and partnership work: Hedges described an active monitoring and upstream tracing effort and said Fairfax Water is working closely with Upper Occoquan Service Authority (UOSA), local jurisdictions and academics to find and reduce sources. She named two specific contributors found through monitoring and UOSA pretreatment data: the Micron semiconductor facility in Manassas and a regional composting facility formerly called Free State Farms. Hedges said Micron has been "receptive" to discussions about treatment but that no firm timing commitments have been announced.

Fire department action: Assistant Chief John Walzer of the Fire and Rescue Department told the committee the county replaced PFAS-containing firefighting foams about three years ago. "We did replace the PFAS-containing foams about 3 years ago," Walzer said, adding that other jurisdictions in the region have not all made the change.

Board concerns and next steps: Supervisors pressed Fairfax Water about rate impacts and funding. Hedges said wholesale partners will cover about half of the capital cost and that rate projections include larger increases in the short term (under 10% over three to four years) before settling to roughly 5%–6% later. She said there is no appreciable state funding identified and that federal support so far has been limited. Hedges and Board members urged aggressive upstream source identification as a way to reduce long-term treatment needs—an approach some supervisors likened to New York City's watershed protection efforts that avoided building an expensive downstream treatment plant.

Fairfax Water asked the committee to support: expanded monitoring in the Occoquan watershed; county assistance collecting wastewater and stormwater samples; requiring initial storm and wastewater monitoring for land uses likely to use PFAS; product-replacement programs; and backing legislation to protect water utilities and ratepayers from CERCLA liability for properly disposed PFAS-laden residuals. Hedges said the utility will return with pilot results and further updates as the treatment-selection, design and construction process moves forward.