NORWALK, CONN.- On a peninsula projecting into Long Island Sound, an empty road passes through a wild salt marsh where snowy-feathered egrets dot tawny fall grasses and ospreys soar. A small herd of wild turkeys ambles nearby.

This 125-acre tract called Manresa Island, an extension of the Norwalk mainland, offers almost 2 miles of shoreline that opens to views of the Connecticut coastline.

But the reason for this island’s abandonment is also hard to miss: The desolate bulk of a decommissioned 1960 oil-fired power plant, closed by the energy company NRG in 2013, is visible for miles. The company wanted to sell the acreage but the cost of demolishing the plant and cleaning up pollutants discouraged potential buyers.

Now a Norwalk couple has come forward with their own plan to transform the site into a destination park for the city that combines landscape and shoreline restoration with beaches and boating. Austin and Allison McChord are purchasing the site this fall through their new nonprofit, the Manresa Island Corp., and plan to announce their proposal at a news conference Tuesday in Norwalk with local, state and federal officials.

The pair said they intend to entirely fund the cleanup, as well as the design and construction of the park, which includes the conversion of a multistory power plant to host recreational spaces, a community event hall and facilities that partner with local institutions for shoreline studies. They also intend to endow its operation in perpetuity.

Austin McChord, who grew up in the city, founded Datto, a cybersecurity and data backup company, in his parents’ house. He sold it to Vista Equity Partners for $1.3 billion in 2017.

He said he was kayaking around the shoreline with his wife, Allison, an architect, when they noticed the wealth of nature and asked themselves whether they could buy the site and turn it into a park. “We started to pull the thread,” by talking to the mayor and other leaders, “and the answer was not no,” Austin McChord said during a tour of the island.

After further analysis, the couple offered to take on the project themselves. This fall, their nonprofit will close on the purchase from Argent Ventures, which acquired Manresa Island last year and planned to redevelop the site for housing. The couple’s promised gift has remained a closely held secret among a few local leaders until now.

The McChords commissioned a vision plan for the project, hiring SCAPE, a landscape architecture firm known for its designs of public spaces that restore habitats and are resilient to the effects of climate change. Led by Kate Orff, the firm plans to restore damaged landscapes and make them accessible with a boardwalk and a walkway through the forest treetops. Orff, in an interview, said the design includes “living shorelines” using native plantings, while creating new swimming areas and a boat launch.

The McChords decided that the raw industrial grandeur of the power plant deserved to find new uses. They brought in Bjarke Ingels of the architecture firm BIG, which proposes to turn the 70-foot-high turbine hall into a community event space.

In the 170-foot-tall boiler building a dense steam-generating infrastructure will be removed to reveal the robust network of supporting steel columns and beams. “The steel frame is so muscular that I could propose hanging swimming pools and not be thought irrational,” Ingels said in an interview.

Austin McChord declined to disclose the purchase price of the island, though a person close to the project, who was not authorized to speak publicly, said it was $40 million. Cleaning up the site may cost as much as $80 million. With many elements of the plan yet to be finalized, McChord said that he did not know the overall cost of the project, except to say that it could total “hundreds of millions of dollars,” since he is not looking for government aid or for other philanthropists to chip in. Roughly comparable is the $180 million gift by Joshua Rechnitz that made possible the remediation of a polluted site and the conversion of a much smaller generating plant into Powerhouse Arts in Brooklyn, which opened last year.

Reflecting on the couple’s decision to fund the park, Austin McChord said, “You can get stuck trying to find the most worthy place to put your charitable dollars. We found it easy to bond with this particular place.” Allison McChord added, “It was just, like, we jumped.”

Asked about the impact of such a project on his city, Mayor Harry Rilling of Norwalk said, “I think it will be an economic driver. Visitors will want to patronize our local businesses and eat in our restaurants.”

There are few precedents for such a gift, said David Callahan, the founder of the digital site Inside Philanthropy. “The Gathering Place in Tulsa springs to mind,” he said, referring to a $465 million river park largely underwritten by George Kaiser, a local billionaire, that opened in 2018. Callahan also cited Little Island, the $260 million park perched above the Hudson River. Donations by the media mogul Barry Diller and the designer Diane von Furstenberg largely underwrote the park’s construction and endowed years of its operation.

But is a park “free” to the city too good to be true? Callahan said there could be pushback if a donor is perceived as “swooping in to transform the whole neighborhood,” and setting the agenda. That was a source of resistance to Little Island, he said. People also may protest negative local impact, such as traffic or gentrification.

The nonprofit plans to engage residents in evaluating the plans. The McChords said they hope that much of the park can be open by 2030. Rilling, for his part, thinks the vision will find wide acceptance. The redevelopment “fits with our plan for conservation and development,” he said. “The power plant has been an eyesore since they built it. It’s not something Norwalk wanted.”

This article originally appeared in The New York Times.