Vermont's largest solar farm to go online at Superfund site

by Timothy McQuiston Vermont Business Magazine The developers of the largest solar array in Vermont expect the project to begin selling electricity by the end of September. The project is being developed by Boston-based Greenwood Energy. According to its partner in the solar project, Brightfields Development LLC of Wellesley, MA, construction commenced in May on the 4.99 megawattsolar projectat theElizabeth Mine Superfund Site, which sits mostly in Strafford.

The Elizabeth Mine solar array is the largest in the state, slightly larger than the one located in Williston at GlobalFoundries (4.7 MW), which went online in 2016. A similar 4.99 MW site is planned for Weybridge.

An even larger project is planned for Ludlow and could begin construction by the end of this year. Coolidge Solar I, LLC, developed by Ranger Solar from Maine, was granted a certificate of public good in March to construct a 20 MW solar electric array. The power is scheduled to be sold entirely to Connecticut utilities, as part of a 20-year power purchase agreement.

Coolidge Solar is expected to operate beyond the 20-year Connecticut PPA, after which, its energy, capacity, and Renewable Energy Certificates (RECs or credits) could help meet Vermont’s need for energy and capacity, accord to the Vermont Public Utilities Commission. Its RECs, according to the PUC, could also help meet Vermont’s renewable energy requirements, which continue to grow until 2032 (75 percent retail electric sales from renewable energy) under Vermont’s Renewable Energy Standard.

Greenwood financed the Elizabeth Mine project, which was designed by Brightfields. Greenwood also developed a solar array in Coventry. Coventry is a 2.7 MW solar project.

Unlike the Ludlow project, the Elizabeth Mine electricity will hook into the Green Mountain Power system.

The town of Strafford asked the PUC to include language in the CPG to ensure that Vermont would be the beneficiary of the RECs after the 10-year contract with Connecticut concludes.

According to GMP VP Kristin Carlson, GMP has committed to begin retiring RECs from the project starting in year 7 of the Project’s operation, and retiring all RECs from the Project at the 10-year operation mark.

GMP purchased all of the energy, capacity, and RECs from the project.

As for its current portfolio, Carlson said for FY 17 GMP expects to sell just under 600,000 RECs, or 13 percent of its renewable generation.

Vermont utilities, especially GMP and Burlington Electric Department, have been very active in arbitraging renewable energy sourced in their service areas by selling the RECs out of state. The state of Connecticut, which has high renewable energy goals but relatively little of its own generation, has been an aggressive buyer of the RECs.

BED sells most of its own renewable energy generation for a premium and then buys RECs at the wholesale levelto lower costs to its own ratepayers. GMP uses the same strategy to maintain lower rates.

In 2014, Burlington Electric became the first city in the USto source 100 percent of its power from renewable generation.BED generates REC power mostly from the McNeil wood chip plant and its Winooski River hydro station.

BED Communications Manager Mike Kanarick said, "While our generation portfolio includes biomass, wind, solar, and hydropower, we are both a buyer and seller of RECs to ensure that we can maintain a 100% renewable portfolio and achieve low and stable rates for our customers. In 2016, we purchased (and retired) RECs from renewable sources (primarily hydropower), and retained (and retired) RECs from some of our own solar and hydropower resources. The total of our retired renewable RECs exceeded Burlington Electric’s load."

GMP also sells some of its renewable energy as RECs. It retains some as part of Vermont's own renewable energy requirements. It generates power mostly from the Lowell Mountain wind farm, from over 30 dams it owns or leases around the state, and from solar generation.

The Elizabeth Mine Superfund Site is an abandoned copper mine straddling the Towns of Strafford and Thetford.The mine operated from the early 1800s until its closure in 1958. During that time, three million tons of ore were mined, producing more than 90 million pounds of copper.

Today, the Elizabeth Mine is an EPA regulated Superfund Site that underwent an extensive environmental remediation in 2011. Another $10 million in remediation is planned and waiting for funding.

Brightfields has been working with its development partners, Wolfe Energy of Strafford and Greenwood Energy to turn this mineral extraction site into a source of clean energy. They filed their CPG petition in October 2015 and received it in June 2016. Greenwood Energy ( is the international clean energy division of the Libra Group (, a privately owned international business group comprising 30 subsidiaries active across six continents.

The development team said in a statement that it was able to craft a design that maximized energy production while protecting the integrity of site’s remedial cap. Once completed, the 4.7 MW project will produce8,850,000 kWh of electricity every year, enough energy topower over1,200 homes. It willoffset6,272 tons of carbon dioxide every year, the equivalent to burning 14,192 barrels of oil.

On June 29, 2016, the Vermont Public Service Board (now the PUC) issued a CPG approving, subject to certain conditions, the installation and operation of a 4.99 MW solar electric generation facility on land within the Elizabeth Mine Superfund by Elizabeth Mine Solar I, LLC (the “CPG Holder”).

The CPG Holder was required to pay a $500 fine after it self-reported on May 5 that construction “preparations” commenced on April 20, 2017, and site construction began on April 24. The developer was required by the PUC to obtain a letter of credit before it could begin construction. The letter also was filed May 5.

The PUC acknowledged leniency in the fine because of the short duration between the two events and the self-reporting. The fine could have been as high as $40,000.

A story in The Herald on April 27 reported that construction had already begun at the site.

The developer was required to take care not to disturb the Superfund site. The remediation action on the site consisted of stabilizing the old tailings piles on the site, and then “capping” those materials under an impermeable geosynthetic membrane, which was then covered with soil.

Brownfield sites are being used for solar projects in Vermont, as at Coventry and at the former landfill in South Burlington, because there is little else that can be done at these sites and solar arrays have little construction impact.

At the beginning of the CPG process before the PUC, the members of the Town of Strafford Selectboard expressed “profound” disappointment that the Town would need to engage in a legal process to become an official party and to present evidence.

Returning the RECs to Vermont as part of the CPG is credited to the Stafford Selectboard.

The solar array consists of 1,255 groups of eighteen (18) 310 watt solar panels. The solar panels will be mounted on poured-in-place ballasted racks of 18 panels each (two rows of nine panels mounted in portrait mode), covering approximately 28 acres of open field, which is the cap for remediated Tailings Piles 1 and 2. The poured-in-place ballasts do not require any earth disturbance, but will sit on top of the existing soil, thus protecting the engineered tailings pile cap.

The operation of the Project is totally automatic and requires no on-site personnel.

At the time the CPG was issued, the project was expected to generate an annual property tax payment of $20,000 to the State of Vermont, or $600,000 over its expected 30-year life. Dependent on the outcome of the property valuation, the project was expected to pay $10,000-$30,000 per year in aggregate local property tax to the Towns of Stafford and Thetford, or $300,000-$900,000 over 30 years.

Elizabeth Mine History

According to the Vermont Department of Environmental Conservation ( the Orange County copper district ores were discovered in 1793, with production beginning in the early 1830s. Until Michigan copper ores were discovered in 1846, Vermont was the chief copper producer in the United States. The Elizabeth Mine, located in South Strafford, was the nation’s largest copper mine until the Michigan deposits opened. Vermont copper mines operated sporadically through the 1950s, and the closing of the Elizabeth Mine in 1958 brought an end to metal mining in Vermont. Ore minerals have not been exhausted in the Orange County copper district, but the ore grade is marginal and structural complexity makes mining extremely difficult.

According to the EPA, the Elizabeth Mine is an abandoned copper mine located on Mine Road in the village of South Strafford, which is part of the town of Strafford in Orange County, Vermont. The area consists of two mine tailings piles, one area of waste rock and heap leach piles, two open-cut mines, several adits (horizontal mine entrances), underground shafts and tunnels, ventilation shafts, and several former ore processing buildings as well as other on-site structures.

Following site investigations, cleanup and environmental monitoring are ongoing. The ore was initially valued for its iron content, and then its pyrrhotite content from which copperas (iron sulfate) was produced. Circa 1830, the deposit was primarily exploited for its copper content based upon the recognition that a significant amount of chalcopyrite (copper iron sulfide) was disseminated in the pyrrhotite.

For nearly a century, intermittent production came from the open-cut mine as underground work did not begin until 1886. During early mining operations, several copper smelters were built on the site. Between 1830 and 1930, about 250,000 tons of ore were mined, from which about 10.5 million pounds of copper were produced. From 1943 to 1958, three million tons of ore were mined, producing more than 90 million pounds of copper. All mining operations ceased in February 1958.