The nation’s largest solar farm built atop a federal Superfund site is now generating power on a tract of land in Indianapolis tainted by a long-shuttered plant’s wood-treating operations.

The 43-acre Maywood Solar Farm went online last month, with more than 36,000 solar panels feeding 8 megawatts of electricity into Indianapolis Power & Light’s power grid.

The solar farm is the largest built to date on a Superfund site, said Environmental Protection Agency spokesman Francisco Arcaute. The next largest is a 40-acre, 6-megawatt solar farm near Rancho Cordova, Calif.

EPA Region 5 Administrator Susan Hedman said in a statement that the Indianapolis solar farm “has transformed a site with a long history of contamination into a source of renewable energy for the future.”

The agency is encouraging the development of solar, wind and other renewable energy projects on tainted sites. As of last fall, 85 such projects were generating a combined 507 megawatts of power at Superfund sites, landfills and mine sites across the nation.

The Indianapolis property’s owner, Vertellus Specialties Inc., worked with the EPA, solar panel maker Hanwha Q CELLS, Indiana’s environmental agency, the local utility and other partners to develop the solar farm.

The complex covers about a third of the former 120-acre Reilly Tar & Chemical Corp. site. For several decades, workers there refined coal tar and treated railroad ties and telephone poles with the wood-preservative creosote, a possible human carcinogen. That plant closed in 1972.

Testing during the 1980s showed that groundwater beneath the site was contaminated with the toxic fuel additive benzene, the highly corrosive compound pyridine and ammonia.

After the site was cleaned up in the 1980s by crews overseen by the EPA, it was capped with soil and gravel and a ground water containment system was installed.

Reilly Industries — the site’s former owner — merged with Rutherford Chemicals merged in 2006, creating current site owner Vertellus.

Vertellus President and CEO Rich Preziotti said the project has put into productive use idle land on Indianapolis’ southwest side that had served as storage space for shipping trailers since the mid-1990s.

“We’re using this land in a really neat way — we’re providing renewable energy to the community and getting some value from that land,” Preziotti said.

The company’s lease with the solar panel maker calls for the farm to operate for up to 30 years.

Arcaute said Hanwha Q CELLS’ original design for installing the solar panels called for trenching and a significant amount of soil disturbance of the site, but the company worked with the EPA to retool its design to reduce soil-disruption by more than 90 percent and use the site’s existing topography.

The solar farm is part of Indianapolis Power & Light’s goal of eventually adding 99 megawatts of solar-generated electricity — enough to power for about 10,000 homes — to its energy sources, IPL spokeswoman Brandi Davis-Handy said. The utility currently receives about half that amount of electricity from 23 solar projects, including a 75-acre solar farm at the Indianapolis International Airport.