Decontamination of plumbing pipes contaminated with Per- and polyfluoroalkyl substances (PFAS) from Aqueous Film Forming Foams (AFFF) - Decon Conference
Citation:
Szabo, J., M. Magnuson, S. Witt, D. Schupp, N. Sojda, AND B. Murugesan. Decontamination of plumbing pipes contaminated with Per- and polyfluoroalkyl substances (PFAS) from Aqueous Film Forming Foams (AFFF) - Decon Conference. Presented at 2023 EPA International Decontamination Research and Development Conference, Charleston, SC, December 05 - 07, 2023.
Impact/Purpose:
Data produced from this research will give water utilities and homeowners information on whether flushing their plumbing is effective at removing PFAS from AFFF. This would be a key question asked in the event of AFFF backflow.
Description:
Home plumbing can be contaminated with PFAS from aqueous film forming foams (AFFF) through accidental backflow resulting from firefighting related activities, including back-siphoning during routine maintenance of equipment. This exact incident did occur in Wyoming, OH in 2018, Neville Island, PA in 2019 and Westmoreland County, PA in 2020. As of now, no known, intentional studies of PFAS persistence on any home plumbing materials have been performed. In order to determine if PFAS persists on home plumbing materials, a pilot scale setup containing copper, polyvinyl chloride (PVC), and cross-linked polyethylene (PEX) pipes was built (see pictures on the next page). Three pipes of each material were installed so that triplicate experiments could be conducted simultaneously. Pipes are 1-inch diameter, 55 inches long and are supplied with local tap water. Flow through each pipe is regulated with a solenoid valve that opens on the hour between 7:00 am and 4:00 pm for 10 min and allows flow at 2 gpm. This demand pattern results in 200 gallons flowing through each pipe each day, with stagnation between the openings and overnight. Pipes were conditioned using this flow pattern for four months. Two separate experiments will be conducted in July and November 2021 with pipes replaced in between and conditioning restarted. After conditioning, the pipes will be contaminated with a 3% solution of 3M Lightwater AFFF, which is an older formulation containing PFOS and PFOA. Two experiments will be conducted. In one, the AFFF contamination will contact the pipes for 4 hours (July experiment). In the second, contact time will be 7 days (November experiment). After the contamination period, the pipes will be flushed for 20 minutes at 4 gpm. After flushing, the normal daily demand pattern will be reestablished for two days, with one additional four-day period of stagnation thereafter. Sampling will continue for the six-day post-flushing period. The contamination duration will help determine if initial contact time influences PFAS persistence. Samples will be taken before and after stagnation periods to determine if the initial flushing is enough to remove any adhered PFAS, or if it releases from the pipes after stagnation. All water samples will be analyzed with EPA Method 537.1, LC MS/MS Compliant with QSM Table B-15, Revision 5.1 and higher. All data was delivered a Level 4 DOD QSM package.