GREENSBORO Local and state guardians of water quality hope to learn much from planned, residential well tests around Piedmont Triad International Airport seeking worrisome levels of the industrial chemicals PFOS and PFOA.

Greensboro, Guilford County and state officials are hosting a meeting about the tests Tuesday evening for people living near PTI and along streams that rise in that part of Greensboro — as well as for anybody else who is interested.

They are hoping for a good turnout by residents open to the testing that officials say aims both to insure residents’ well water is safe and to help define the extent, if any, that PFOS in particular has polluted ground water beyond the airport vicinity.

The public meeting at Guilford College United Methodist Church follows the Nov. 15 announcement by officials from the N.C. Department of Environmental Quality, the state Department of Health and Human Services, the county and city that they are joining forces to sample more than 50 residential wells later this month for signs of PFOS and PFOA.

Public response so far has not been overwhelming. Guilford environmental health manager Joe Johnson said that Thanksgiving week, the county sent letters to 64 well owners asking permission to test their drinking water and alerting them to Tuesday’s gathering.

He said that by late last week, his office had received signed permission slips from 11 of the letter recipients. He is hopeful more are in the mail or will be hand delivered at the Tuesday meeting.

Johnson said that in the aftermath of the well-testing announcement last month, he and his staff fielded telephone inquiries about the testing from only a few callers.

“We don’t know it if will be two or 200. I hope it’s the latter,” Johnson said of Tuesday’s turnout.

So far, there is no hard evidence that residents using household wells in western Guilford have anything to fear from either PFOS or PFOA. But PFOS especially has been found at concerning levels in airport-area streams and in the Lake Brandt reservoir fed by those streams, primarily Horse Pen and Brush creeks.

The planned testing of household wells is the most recent upshot of the discovery several years ago by Greensboro Water Resources officials that Lake Brandt reservoir has fluctuating levels of PFOS and PFOA, which at times spike above the federal government’s threshold of 70 parts per trillion.

The city water department spent months tracking the source of that contamination upstream through the watershed to PTI and the industrial area that surrounds it.

The two chemicals are part of a class of compounds known as perfluoroalkyl substances — PFAS, for short — that were heavily used for decades in manufacturing a variety of household, outdoors and fire-safety products.

“Through our watershed study, the city has a pretty good idea of how PFAS impacts local surface waters,” Greensboro water-quality supervisor Peter Schneider said last week in an email. “However, with the exception of two industrial sites at FINA and the US Airways Hangar B and the associated monitoring wells, we don’t really know the overall impacts to the ground water in the impacted area.”

The hangar is on PTI property as are some monitoring wells for the former Fina Oil & Chemical Co. The wells were installed after several underground pools of leaked petroleum products were discovered migrating from the tank farm under West Market Street onto the airport grounds in the late ’80s.

City water officials took samples from the Fina and US Airways monitoring wells drilled for other types of pollution to now help them better define the boundaries of contamination by PFOS, PFOA and other PFAS compounds.

They have found a wide range of readings for the various PFAS compounds in the PTI monitoring wells, from zero all the way to 1,588 ppt for all the perfluoroalkyls in one airport well, which had PFOS at 311 ppt and PFOA at 170 ppt.

The federal government’s 70 ppt “health advisory” is the voluntary, unregulated warning level for avoiding health risks for someone who drinks water with that concentration of PFOS alone or in combination with PFOA.

The advisory applies to the health consequences for someone drinking roughly two quarts of water with that level of PFOS, PFOA or the two together every day for a lifetime.

City drinking water from the Mitchell Water Treatment Plant that draws from Lake Brandt usually tests well below the 70 ppt advisory, but has jumped as high as 100 ppt at erratic intervals with PFOS making up the majority of the PFAS contamination.

City officials recently installed specialized equipment at the Mitchell plant to reduce PFOS and PFOA to acceptable levels when such spikes are detected.

Researchers know that excessive exposure to PFOS and its related chemicals is linked to problems with high cholesterol, thyroid function, the immune system and reproductive disorders. Some studies also have found a presumed linkage between these chemicals and certain types of cancer.

PFOS made its lasting mark on the world as a major additive in firefighting foams. Such foams have been heavily used by PTI’s emergency responders and most other U.S. airports.

Other area fire departments also used PFOS-containing foams for training and actual firefighting in the area around the airport. In addition, some industrial buildings nearby were equipped with interior, fire-suppression systems that relied on similar chemical formulations.

PFOA is best known for its role in making stick-resistant Teflon surfaces, but also once was used widely in such other consumer goods as the interior lining of microwave popcorn bags.

Manufacturers began voluntarily phasing out PFOS and PFOA years ago after scientists grew concerned that most humans carry some of these totally synthetic compounds in their bloodstream.

PFOS has a half life of about five years, meaning it takes that long for half the amount a person consumes at any one time to dissipate.

PFOS and PFOA are particularly difficult for environmental regulators to identify because they dilute so readily in liquid that they leave no visual trace or telltale odor and persist indefinitely in the environment.

The only way to accurately quantify them is through scientific testing that can be costly, but which is being offered free of charge to the letter recipients.

Local health officials sent their state counterparts a list of household wells throughout the watershed earlier this year, and state environmental and health experts picked sites for testing that they believe would help provide a more complete picture of PFOS/PFOA contamination, Johnson said.

“My sincere hope is that we don’t get any hits” for either of the two man-made chemical compounds in the planned testing, he said.

“If we do get hits, especially in a particular neighborhood, I would expect that we would do more testing,” Johnson said.

Schneider said that in addition to wanting the results of the upcoming tests to improve their understanding of how PFOS, PFOA and other PFAS pollutants are moving toward Lake Brandt, city officials also “support the county in making sure these residents have clean, safe drinking water.”

“Given the values of PFOS/PFOA in the surface waters near some of the well locations, it is the right thing and the logical next step to sample these wells,” Schneider said of residential wells in the airport area.

The testing is planned for later this month, and residents would not have to be at home when it occurs. Health department staff members would attach a hose to an outside faucet, let the water run for about 15 minutes and then take samples in two small bottles.

Johnson said the testers let the water run that long to make sure they are getting their samples “straight out of the well, not sitting in a pressure tank or water heater.”

Laboratory results for each sample will be returned within 45 days after it is drawn.

Schneider said that in addition to informing residents of their wells’ water quality and expanding everyone’s understanding of PFOS-PFOA issues in western Guilford, the household testing could help city officials develop techniques to “alert our water supply folks when to operate the PAC feed system at the water treatment plants” recently installed to counteract the two contaminants before they reach problem levels.

Beyond that, Schneider said the well-testing could play a role of nationwide significance, helping to fill gaps in the current level of scientific knowledge about how an exceedingly stealthy class of pollutant moves through the environment.

“Data from wells, along with surface water samples, are proving to be very helpful to state and federal agencies as they continue to try and understand how this unregulated contaminant is impacting not only our state but the nation’s water supplies,” Schneider said.

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Contact Taft Wireback at 336-373-7100 and follow @TaftWirebackNR on Twitter.

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