Read the full article by Mara Hoplamazian (NH Public Radio)
… “When PFAS chemicals make their way into soil, there’s concern that humans could be harmed — through ingesting the dirt, or maybe through eating vegetables grown on the land. And as the compounds move through the soil into groundwater, they could also get into drinking water.
New Hampshire already has a ‘direct contact’ standard for PFAS in soil, which is meant to protect people who might ingest the soil or get it on their skin. Now, the state is focused on how to set levels for PFAS in soil that would protect groundwater, the source of drinking water for 60 percent of Granite Staters.
Developing that standard is not a simple process. Regulators say it needs to be airtight. It could be challenged in court, possibly by the companies that produce PFAS chemicals or sell biosolids as fertilizer, as New Hampshire’s drinking water standards were in 2019.
So, the Department of Environmental Services is working closely with federal scientists to back the standard up with a study looking at two main things: how widespread contamination is across all the soils in the state, and how PFAS move around in the environment.
Andrea Tokranov, a hydrologist with the US Geological Survey, is helping lead that study. For the first objective, her team tested 100 soil samples from locations across the state that had no known sources of PFAS contamination. She says that has relevance, even outside of New Hampshire.
‘Nobody knows what’s in your soil, even if you don’t have a [contamination] source locally. We don’t know the answer to that. And I think this study contributes to that quite a lot,’ she said.
For the second objective, she says the scientists are on the hunt for one value in particular: a partitioning coefficient.
That’s a parameter that can be used in scientific models to determine how much PFAS stays in soil, and how much moves into water, when it’s mixed with both soil and water at the same time.
There are thousands of PFAS compounds, and they all look a little different. The ones that have longer chains of molecules have high partitioning coefficients, meaning that they get stuck in soil and could pose less of a problem for groundwater, Tokranov says. And the shorter ones can travel a lot more in the environment. Different soils can also change that value.
The study’s numbers will be specific to New Hampshire soils and will help the state build their standard. Tokranov says they’re also building out the scientific literature on PFAS, which other New England states say they’re watching.
In New Hampshire, state regulators are required to propose a soil standard to state legislators by November 2023.
The main goal of the standard is to add to the rules for contaminated sites. The party responsible for the PFAS contamination would need to remediate the soil so it meets the state’s standards.
On the biosolids side, the soil standard will also lay the groundwork for a standard for PFAS in sludge. Regulators plan to start sampling the soil where biosolids have been spread to see if they need to become part of the contaminated sites program.
Regulators can only sample some of the biosolids sites in the state — those that are required to have a permit to spread the material. For other sites, which spread biosolids that are further treated and don’t need to have individual permits, the state would need to get permission from landowners, Drouin said.” …