Landfill legacy - groundwater pollution and solar promise

There is an acute housing shortage. Water quality around the Post Mills landfill isn't helping.

Landfill legacy - groundwater pollution and solar promise
View at the top of the capped landfill. The Post Mills Airport lies to the left and the Post Mills Nature Area extends into the distance at the right.

Although the Post Mills Landfill, officially known as the Upper Valley Regional Landfill (UVRL), has been closed since 1989, issues caused by its history are of concern to this day.

The landfill was shuttered because it lacked an impervious liner. As a result, rainwater percolating through layers of compacted garbage carried a plethora of chemicals into the underlying soil from household cleaners, organic compounds from paint and commercial products, heavy metals, and more. This unwholesome soup entered the groundwater in the fractured rock aquifer that supplied nearby wells. It took several court settlements, completed by 2000, to provide the affected residents with a new, clean water supply and to close and cap the landfill. The State assumed responsibility for the latter. The remaining settlement money was put into a fund held by the Waste Management and Prevention Division of the VT Department of Environmental Conservation (DEC), to pay for yearly testing of the groundwater around the landfill.

In 1999, the Town submitted a grant proposal to the DEC to study the flow of groundwater in the fractured rock aquifer near the landfill. The purpose was to identify areas that could – or could not – be used for wells. Total cost of the project at the time was to be  $151,500, of which the US Geological Survey (USGS) was committed to funding $65,000. The 1999 Town Meeting appropriated $16,500. The Town was asking the State to allocate $50K from its pot of federal Clean Water Act funds, plus another $20K from state funds. The State denied the request, and the study was never done, leaving Post Mills in the dark about the true extent of the aquifer contamination.

`Bedrock Fracture Trace Analysis of the area around the Post Mills landfill. The fracture traces are extrapolated from above-ground observations of rock fractures.

The situation remained as such until increasing awareness of fossil fuel energy and its effect on the climate ushered in a tide of solar panel installations. The Thetford Energy Committee was instrumental in facilitating solar arrays in various places, and the capped landfill offered a south-facing, open field that attracted interest as a prime site for a solar array, and a big one at that.

The Energy Committee started looking seriously at the landfill as a solar site in 2014. It turned out to be a challenging project. This property, with its contentious history, had not been bequeathed to anybody. In other words, it had become an “orphan property.” The Town was not willing to take it because of the liability it represented. Without a legal owner there was nobody with whom to negotiate the terms of installing a solar array. In 2016 the Energy Committee, with selectboard approval, turned to the Green Mountain Economic Development Corporation (GMEDC) to see if they could be brought in to help with this impasse.

In a nutshell, then-CEO of GMEDC, Bob Haynes, agreed in principle that GMEDC would explore taking ownership of the landfill, with the idea that it would then rent the property to a solar developer. However, GMEDC was not willing to inherit any of the liability associated with the landfill. And in fact, under VT law, they may be protected from such liability under the Brownfields Reuse and Environmental Liability Limitation Act, or BRELLA for short.  Application for this protection is a multi-stage process. It involves, as one of several steps, an Environmental Site Assessment (phase II ESA) to define the nature, source, and extent of the contamination. The 2021 estimated cost of performing this work is $46,581, of which about $35,000 may come from state funding. As of July, the remaining $10,000 or so is still being sought “from a second round of disbursement.

This difficulty in obtaining funds has delayed the already slow progress toward reusing the landfill as a solar site. This is in spite of a 2021 statement from Governor Scott in which he proposed a $25 million-dollar brownfield cleanup fund and specifically identified the Post Mills landfill as one of Vermont’s priority sites.

The Town would also like to see the ESA move forward, for different reasons. There is now an acute housing shortage. In response to a State initiative, the Town is in the process of revising its Zoning Bylaw to facilitate new housing development in villages like Post Mills. But to be developable, housing lots need a clean, potable water supply. The question of how far from the landfill does the contamination reach becomes critical. Back in 1990, the first water supply that replaced the tainted wells of residents was also found to be contaminated. The well was on the other side of Route 113 from the landfill. (The current Post Mills Water Association’s well is far from the landfill in the opposite direction.) Such duplication of effort and expense underscores the need for the Town’s 1999 proposed study of the Post Mills aquifer, of which the state was unsupportive.

And there is more to it. Three years ago the state acknowledged that “Other contaminants are now known to be associated with landfill leachate that may not have been as well documented in the past, including per- and polyfluoroalkyl substances (PFAS), polychlorinated biphenyls (PCBs), dioxins, 1,4-dioxane, and semi-volatile organic compounds (SVOCs).”

Indeed, when the testing at Post Mills was expanded to look for PFAS three years ago, PFAS was found at levels near, or in one well, above, the Maximum Contaminant Level allowed in Vermont. Human studies have found associations between PFAS (PFOA and/or PFOS) exposure and effects on the immune system, the cardiovascular system, human development (e.g. decreased birth weight), and cancer.

Unlike most other organic compounds, PFAS – also called “forever chemicals” – do not break down. This raises the prospect that the aquifer for some distance around the landfill must be tested in perpetuity and may never be used for a drinking water supply. However, the fund that pays for the water testing will not last into perpetuity. It was originally thought that by the time the fund ran out, the organic contaminants in the landfill would have decayed. But not so with PFAS.

And thus a bigger question looms. If GMEDC does take possession of the landfill, and the fund for water testing runs out, who is then responsible for financing the testing?

To add another complication, the federal EPA recently lowered its Health Advisory for PFAS in drinking water by several orders of magnitude. (Interim updated Health Advisory for PFOA = 0.004 parts per trillion (ppt) ; Interim updated Health Advisory for PFOS = 0.02 ppt.) If Vermont were to lower its current standard (20 parts per trillion for combined PFAS) to anything approaching the EPA Advisory, many more wells might show up as contaminated.

Under GMEDC’s application for BRELLA protection, the ESA promises more information on the aquifer using tests of existing bedrock wells, both landfill-monitoring and private. New monitoring wells will not be drilled as this risks opening more routes for contaminants to enter the aquifer from surficial soils.

Without the results of the ESA, the Town is hampered in its ability to develop housing. Residents in south Post Mills are uncertain whether they can create more residential lots or even start businesses that increase water consumption, such as raising livestock. Both GMEDC and the Town have a high level of interest in the quest for the final $10,000 to finance the study.

Map Credit: Lincoln Applied Geology

Subscribe to Sidenote

Sign up now to get the latest stories right in your inbox.