Measuring PFAS in drinking water is a moving target

Published January 23, 2020

By MAUREEN DOHERTY

NORTH READING — When it comes to measuring PFAS contaminants in drinking water, the testing protocol has been a moving target for the suppliers of public drinking water because a “maximum contaminant level” or MCL has not yet been established by the U.S. Environmental Protection Agency, according to Water Superintendent Mark Clark.

Instead, four years ago the EPA established a lifetime “health advisory” of 70 parts per trillion (ppt) for two types of the chemical (PFOS and PFOA). Subsequently, in June 2018, the Mass. Department of Environmental Protection set its own “public health guideline” of 70 ppt for any combination of five types of PFAS (PFOS, PFOA, PHFpA, PFNA and PFHxS).

Then, in December 2019, Mass. DEP upped the ante by initiating a process to recommend a health advisory that would drop the acceptable MCL from 70 ppt to 20 ppt while adding a sixth type to the mix, PFDA.

Clark stated that under the Safe Drinking Water Act, the U.S. EPA establishes the MCL for drinking water contaminants based on exposure to a particular chemical over a typical 70- to 80-year lifetime of water consumption.

These man-made chemicals, which have been around since the 1940s and are most well known for use in products like Teflon for non-stick cookware or Scotchgard for stain-resistant carpets and upholstery, and for fire suppression systems, are considered unregulated contaminants, therefore the town’s Water Department has been required to monitor their presence in both its own wells and at the interconnections with Andover, he said.

Under the analytical methodologies in use in 2014 and 2015, the town’s wells met those 70 ppt standards as “not detected,” Clark said in an update to the Select Board Jan. 13. However, in November 2019, both North Reading and Andover collected additional samples to be “analyzed to the new recommended standards.”

While all of the Andover sources tested well below the new state recommendations, ranging from 3.9 to 11.8 ppt, two of the sources tested at North Reading’s wells were slightly above that level at 22.6 ppt on November 13.

It was emphasized that both wells are currently out of service for normal winter maintenance and Clark said the town can meet its winter water demands with the supply currently provided by Andover under its permit withdrawal limits. Once the demand increases in the spring and summer months however, due to irrigation use throughout town, it will be harder to meet those demands.

In the interim, about two weeks ago the town initiated steps to test many more samples of water throughout town and is now awaiting the test results from the lab, which could take at least six weeks given the current backlog created by the demand from communities throughout the state that need to know where they stand in relation to the new standards and how to abate it, if necessary.

Clark said additional water samples were collected at the following locations: North Reading’s wells (raw water); Railroad Bed Wells (2), Lakeside Well No. 4, Route 125 Well; North Reading’s Water Treatment Plants (finished water); Lakeside Boulevard WTP and West Village WTP; Andover Interconnections at Main Street and Central Street, plus distribution system samples at all schools (High School/Middle School, Batchelder School, Hood School, Little School) as well as Town Hall and Swan Pond water storage tank.

PFAS are “very resistant to natural breakdown,” Clark said, which means the same qualities valued in these chemicals — their ability to repel water, prevent stains from damaging fabrics and carpets, and suppressing fires — are also the worst qualities about them.

So how do PFAS enter the water supply?

One example Clark used was improper disposal of goods manufactured with these chemicals. Say 20 years ago a resident chose not to dispose of old carpeting the correct way — by cutting it into three-foot strips, rolling it up and putting it on the curb with the weekly trash — and instead had tossed it into the woods. Over time, he said, those carpet fibers would break down, but the PFAS chemicals in those fibers would be left behind and would seep into the soil and groundwater.

“The fibers of carpet will degrade but that chemical will not degrade,” Clark explained. “And since a part per trillion (ppt) is such a miniscule number it only takes a little bit of the chemical to work its way into groundwater and surface water.”

Other sources for PFAS contamination include airfields, fire training areas, manufacturing facilities, waste disposal sites and landfills.

In lab animals, exposure to the PFAS family of chemicals may lead to developmental effects in fetuses and infants and they also may affect the thyroid, liver, kidneys, certain hormones, and the immune system while also having the potential to cause cancer, he said. “While they have some definite benefits they cause some problems,” Clark said.

But he stressed that North Reading is currently in compliance with the known standards and the town is in a much better position than many communities because of the town’s intention to purchase 100 percent of its water from Andover by July 1, 2021. Knowing Andover’s water supply meets the new recommendations is a plus. The town obtains about 70 percent of its water on a year-round basis from Andover; more in the summer months and less in the cold weather months.

Select Board Chairwoman Kate Manupelli asked Clark what methods would be available for the town to eliminate PFAS from its drinking water.

Clark said granular activated carbon is a good method for improving the taste and removing odors as well as PFAS from water, however, it is extremely expensive. “Adding carbon filtration is several million dollars, even at our level” of usage, he said.

Select Board member Stephen O’Leary commented it is hoped that the state DEP will “expedite” the permitting process the town is currently undergoing to increase its withdrawal limits and approve an amended interbasin transfer between Andover and North Reading as the town moves toward shutting down its own wells.

“They may allow us to draw beyond our permitted levels. In doing so, it may impact our ability to allow people to water their lawns,” O’Leary said.

Such action by the DEP would likely require an “emergency” declaration by the agency, Clark said, explaining that this would be a “term the public will be hearing in summer months if we are not turning on our own wells.”