Inside GenOn’s Potomac River Generating Station, the huge boiler hanging from the eight-story ceiling is cool now. The giant steam-driven turbines, rounded as a bodybuilder’s shoulders, are stilled. The hands on the gauges of the old control panels, long since replaced by computerized indicators, have stopped rising and falling. There’s only a trace of coal dust on the stairways’ iron railings.

For two generations, the electricity generated here helped power the post-World War II economic boom across the land. It provided a good living for thousands of employees and good profits for shareholders.

An unmistakable landmark, the plant’s five short smokestacks identified the Alexandria riverfront as much as the George Washington Masonic Memorial does from a hill near the King Street Metro station.

Those stacks also pushed untold tons of air pollution into the skies over the District, Maryland and Virginia, marking the plant as the largest single source of air pollution in the Washington region.

Almost 15,000 tons of coal remain in a pile outside the facility, enough to fuel the electrical generating engines for five days. But as of midnight Sunday, the 63-year-old coal-fired power plant will permanently shut down.

(Laris Karklis/The Washington Post)

The end came more than a decade after two citizens discovered the extent of the health hazard from the fine particulates that settled out of the smoke and into the lungs of people who live, work and play nearby. Working on their own and slowly picking up support from neighbors, environmental groups and local, state and federal officials, Elizabeth Chimento and Poul Hertel relied on scientific studies and persistence in the face of multiple setbacks.

‘Always a struggle’

“At this point I’m just very happy this plant is closing and we will not have the harmful pollutants that impacted public health,” Chimento said. “It was always a struggle. . . . This is not an Erin Brockovich movie. This is a lot of hard work.”

“Early on, we wanted to focus on facts and science and policy, and not politics,” said Paul Smedberg (D), an Alexandria City Council member who was the first city official to support their work.

“It was a real community effort. . . . And when you think about the resources that Mirant, then GenOn, threw against us while we basically had three people at first — it took a lot of work, a lot of convincing others.”

Their efforts attracted attention, including a proposal by a nonprofit group that someone spend $450 million to transform it into an eco-friendly project. In July 2011, New York Mayor Michael R. Bloomberg (I) stood on a boat on the Potomac in front of the GenOn plant and donated $50 million from his charitable foundation to support the Sierra Club’s efforts to close the country’s coal-fired plants.

Shifting the credit

GenOn says it wasn’t activism but the changing economics of running a 482-megawatt coal-fired plant that caused the closure. The plant, which provided energy mostly during times of peak usage for the mid-Atlantic power grid, ran for 72 consecutive days this past summer.

The closure is “a market-driven decision,” said Misty Allen, vice president of asset management for GenOn. The changing price of fuel, particularly natural gas, coming changes in federal environmental law and the cost of updating the aged structure all played a role in last year’s decision to close the plant, she said.

What happens next, after 12 to 18 months of deactivation and cleanup, may test the patience of Alexandria residents eager to see something new on the 25-acre waterfront site.

The land is almost certainly going to be redeveloped, although it may be years before that happens.

GenOn holds a prepaid 88-year lease on the land from Pepco, the site’s original owner before it was sold to GenOn’s predecessor, Mirant Energy.

City officials have met with GenOn and Pepco to ensure a smooth shutdown and cleanup, but there have been no talks about what will happen in the future, officials said.

“It’s a gateway to the city, on valuable land right on the river,” said Alexandria Mayor William D. Euille (D), who for years has worked to close the plant. “Whatever happens, it needs to be done right. It should have vitality and be successful.”

A number of consultants and brokers have approached GenOn, which is in the process of merging with NRG Energy, but no offers have been made, Allen said.

First, they will have to remove the outdoor coal pile. The coal will be loaded onto trains in the on-site switchyard, and the land beneath the pile will be excavated, refilled and reseeded. Allen said the coal has been there so long, they don’t know how deep it goes.

City environmental officials also say the site contains underground storage tanks, and they plan to monitor the disposal of waste and the security of the vacant building. Pepco spokesman Bob Hainey noted that there’s a major electrical substation outside the plant, with transmission lines that are in use, a railroad spur and underground utilities. He said Pepco had expressed no interest in shutting down or moving the substation.

“It plays an integral part in delivering power to our customers,” Hainey said.

The work is almost gone from the working waterfront that identified Alexandria as a seaport since the 1700s. All that’s left of the city’s riverfront industrial heritage are a handful of warehouses (two of which are owned by Robinson Terminal, a subsidiary of The Washington Post Co.). Most of the 120 GenOn employees have accepted transfers or chosen retirement, but about six are still looking for work. Euille said the city has been helping them find employment.

Most city officials believe that mixed-use development, with recreation, housing and commercial or nonprofit offices will someday sit on the site.

Redella S. “Del” Pepper (D), the Alexandria council member who with Smedberg co-chaired the local committee that worked on the plant’s shutdown, said its closure and removal gives the area a chance to restore access to the waterfront beyond the existing Mount Vernon bike and pedestrian trail, as well as to create open space, a museum and housing.

“This is really a time for celebration. There’s just no two ways to look at it,” she said. “This was the region’s biggest polluter. . . . It’s really an eyesore, and it’s not appropriate for our historic waterfront.”