PRESQUE ISLE, Maine — Presque Isle Utilities District has to find an alternative for disposing of its wastewater sludge after soil from fields long used to spread the substance tested higher than the state-mandated threshold for the PFOS family of “forever chemicals.”
Maine Department of Environmental Protection established an upper limit of 5.2 parts per billion in soil for PFOS, or perfluorooctanesulfonic acid, and nine out of Presque Isle’s 12 fields tested ranged from 7.6 parts per billion to 27.8 parts per billion for PFOS.
In March, the Maine DEP ordered water utilities to stop spreading wastewater sludge on fields until they tested soils for three synthetic chemicals in the PFOS family long used for fire suppression, non-stick cookware and other products. The chemicals have become a public health concern, as they do not readily break down and they pose health risks in high concentrations.
The soil tests showed levels of the other two chemicals in that family — PFBS and PFOA — were mostly at acceptable levels.
Presque Isle Utilities District superintendent Frank Kearney said that the utility, which is among the few statewide to rely almost exclusively on sludge spreading, has been planning to phase out the practice, but is asking Maine DEP for permission to apply what remains in storage — about 500,000 gallons.
“We’re in a dither. We don’t know what we’re going to do,” Kearney said of the sludge in storage, which is nearing capacity.
For several decades, the utility has spread its wastewater sludge on hayfields it owns totaling just under 200 acres. The practice was a common way around the country to use wastewater as fertilizer, but it has fallen out of favor as land prices have increased for utilities and landowners who may have taken the sludge have become reluctant to use it, Kearney said.
Now, utilities use anaerobic digesters to treat wastewater before discharging it into waterbodies, or they dewater sludge and haul the remaining solids to a landfill. The dewatering process is what the Presque Isle Utilities District board of trustees will be considering, Kearney said.
“We’re talking with a company in the Midwest who specializes in moving mobile dewatering equipment so they can make dirt out of sludge, and it would be taken to Juniper Ridge [in Old Town], the closest landfill,” he said.
In addition to investing in that technology for the long term, the Presque Isle Utilities District may have to hire such a company on a short-term basis to dewater the sludge stored in lagoons near the hayfields, unless the DEP allows the sludge to be spread. Kearney said he’s calculated that applying the current stored sludge would not significantly raise the levels of the chemicals already in the soils.
“With the best information I have right now, this is going to add just a little bit to the contamination that’s already there, he said.”
The issue of PFOS chemicals in Maine wastewater and farm fields arose his year after high levels were found in the water, soil and milk of an Arundel dairy farm where the farmer had spread utility wastewater and paper mill sludge for decades. Many Maine farms applied sludge and the Arundel farm is likely “the tip of the toxic iceberg,” according to Patrick MacRoy of the Environmental Health Strategy Center.
PFOS chemicals were first invented in the 1930s and are so pervasive in ecosystems and animals around the globe even polar bears have them in their bloodstream.
“Society bought it, used it for modern convenience, it went down the toilet,” Kearney said of the PFOS chemicals. “Now, society will pay for what it costs.”
Kearney said he’s also testing the utility’s two main wastewater sources — one from Presque Isle’s residential and commercial areas and one from the Skyway Industrial Park and former Air Force Base.
“With those two samples I hope to learn if the industrial park and the former Air Force Base is bringing it in through ground water,” Kearney said, adding that it’s possible there is legacy PFOS contamination from the Air Force Base and past use of fire suppression chemicals in firefighting training.
“I think household source is steady and steadily declining because of phasing out of the products. I threw mine away,” he said of Teflon non-stick pans.
PFOS chemicals are no longer manufactured in the United States, though they are still imported and used in many applications and products. Many agricultural fields are likely to have PFOS chemicals from additives to pesticides.
“We have determined that a lot of the spray material that all the farmers are using have some of this in it as a surfactant to make the water wetter on the leaves. Same thing as a fire suppression method.”
How to move forward with wastewater treatment will be a topic the Presque Isle Utilities District’s board will discuss in length at its meeting on Aug. 20. Before then, Kearney is meeting with an engineering consultant to learn about options.
“We’ll have to reprioritize our plans at the Dyer Street plant,” he said of the utility’s wastewater treatment plant. “We’re going to have to add dewatering equipment that gets sludge to 30-40 percent solids and then landfill. There’s three or four different ways to do it, but they all require an engineering solution to last the next 50 years.”
Any new treatment option will likely require some increase in wastewater rates for customers, something the utility was on track to do this year anyway to deal with stormwater run off.
The one bit of good news, though, is that Presque Isle’s drinking water is likely to be PFOS free.
Although PFOS chemicals are not regulated at the federal level, the U.S. Environmental Protection Agency has tested for them in some utility drinking water as part of a nationwide randomized sampling program. In 2016, Presque Isle’s drinking water source of river-fed groundwater was tested and it showed no detectable levels of PFOS chemicals.
“We were found to be in the non-detect range, so I’m happy to see that,” Kearney said.
Meanwhile, Maine Attorney General Aaron Frey has joined a coalition of 22 state attorneys general asking Congress to enact regulations for PFOS chemicals as hazardous substances and fund efforts to help clean up affected drinking water, such as watersheds around former military bases.
“These chemicals have been linked to significant negative health effects and have also negatively impacted traditional Maine industries such as farming,” Frey said in a statement.