Trucks haul coal ash from one retention pond to a permanent pond at Dominion Virginia Power's Possum Point power station in Dumfries, Va. (Steve Helber/AP)

For six decades, on a spit of land where Quantico Creek meets the Potomac River, the Possum Point Power Station burned fossil fuels, provided energy for thousands of Virginians and left behind truckloads of a waste product known as coal ash.

Dominion Virginia Power has not burned coal at the 650-acre site, about 30 miles south of Washington, in more than a decade. But what the company plans to do with the ash left behind has caused alarm among area environmentalists and their legal teams, who think the waste and the hazardous heavy metals it contains could leak into the nearby Potomac.

Point Possum — so called because, from the air, the peninsula resembles the profile of a possum’s head — was established in 1948. Dominion officials want to seal the ash from the peninsula in an impermeable pond on the property. They say their plan is safe and will protect the Potomac and Quantico waterways.

The proposal comes on the heels of a legal settlement between Virginia and Duke Energy Carolinas involving another coal ash pond.

Duke agreed last week to pay $2.5 million after a February 2014 spill that sent 39,000 tons of coal ash and about 25 million gallons of coal ash pond water into the Dan River, which reached the Kerr Reservoir in Virginia, according to a Virginia Department of Environmental Quality news release.

Environmentalists say a similar catastrophe could happen at Possum Point in Prince William County.

“We are concerned because of the history of well water contamination near coal ash ponds in other parts of the country, especially North Carolina, where they have found dozens of homes had contaminated drinking water,” said Phillip Musegaas, legal director of Potomac Riverkeeper Network.

“It’s certainly a question at this point here at Possum Point, whether these wells are at risk,” added Musegaas. “But I think we certainly need to find out just to make sure we’re protecting public health.”

State officials downplayed the chances of a spill at Dominion’s five ponds, which the utility began closing in May by consolidating them into a single pond that will eventually be capped.

Coal ash from Pond E is deposited at Pond D at the Possum Point Power Station in Prince William County, Va. Coal ash Pond D is where Dominion Resources is moving all of the existing coal ash. (Kate Patterson /The Washington Post)

“We don’t see any indication that there could be a spill or problems at this point,” said Bill Hayden, a DEQ spokesman.

Dominion plans to cover the final pond with two impermeable layers made of a tough plastic to protect the coal ash from rainwater. On top will be a drainage layer grooved to channel water away from the other layers. On top of that, they will put 18 inches of soil and then another six inches of topsoil to support vegetation on the cap, which officials say will minimize the potential of erosion.

Critics concerned about safety point to the sheer volume of coal ash contained at the Prince William County facility: 3.7 million cubic yards — enough to spread a foot deep over more than 1,800 football fields.

“Most people in Northern Virginia have no idea we have hazardous waste in our back yard on the shores of the Potomac River,” said state Del. Scott A. Surovell (D-Fairfax), a candidate for the 36th District Senate seat. “It’s full of nasty stuff like lead and chromium . . . You go out there in a boat and you see all kinds of people fishing for dinner.”

What’s happening at Possum Point is not isolated. Coal ash ponds around the nation are closing under new Environmental Protection Agency guidelines following a 2008 coal ash spill in Tennessee that flooded 300 acres of land and poured ash into two rivers.

Coal ash contains mercury, cadmium and arsenic — contaminants associated with cancer and various other serious health effects, according to the EPA.

There are two ways coal ash is collected: in a dry form that is kept in landfills, or a sluice — a liquid mix of coal ash and water — contained in ponds such as those at Possum Point. Without proper protections, the EPA says coal ash contaminants can leach into the groundwater and pose significant health concerns.

Coal ash — the material that remains after coal is fired to produce electricity — is not hazardous if managed properly, said Loreal Heebink, a research chemist with the Energy and Environmental Center and member of a team that studied the byproduct. The most important guideline to protect the environment: “Maintain a distance from any rivers,” Heebink said.

“That’s the biggest part,” she continued. “Do not put it near any water that will be a drinking source.”

A warning sign at Dominion Power's Possum Point Power Station is seen in Dumfries, Va. (Steve Helber/AP)

And that’s exactly what critics of Dominion’s plans at Possum Point are trying to find out: Are the ponds dangerously close to Quantico Creek?

“These ponds were excavated into the underlying aquifers, so the ash is in contact with the groundwater,” said Greg Buppert, senior attorney at the Southern Environmental Law Center’s Virginia office. “And closing the ponds with a cap won’t stop metals from leaching into the groundwater and making their way into Quantico Creek.”

Dominion officials say that the plant’s largest — and ultimately final — pond already has a clay liner.

In a June letter to the state Department of Natural Resources, Surovell expressed uncertainty over Dominion’s plan to cap the existing coal ash pond — a procedure known as “cap-in-place.”

Surovell and his legislative colleague, Virginia Sen. Linda T. “Toddy” Puller (D-Fairfax), proposed in the letter to “relocate this toxic waste to dry lined landfill storage away from rivers and drinking water sources.” They also requested that the state test Possum’s wells near the ponds and offer free testing of private drinking wells and water for area residents to determine whether ash has leaked into the groundwater.

“Any type of leaching would concern me,” said Robert Gwin, a 69-year-old retired auditor and criminal investigator who lives down the street from the plant and walks his dog around a coal ash pond. “I’m pretty realistic about things, and I don’t know what the chances are of it leaching out,” he said. “But if I had my druthers, I’d rather they just get it out of here.”

Dominion officials said that if they’re forced to remove the coal ash, a three-year project would become much longer.

Heavy machinery excavate and carry coal ash from drained coal ash Pond E at the Possum Point Power Station in Dumfries, Va. (Kate Patterson /The Washington Post)

“We have a great deal of ash on site, and that process would involve tens of thousands of trucks and take many, many years,” said Pamela Faggert, Dominion’s chief environmental officer and vice president.

“With our plan, we just move the ash on site to a landfill that will be dewatered, capped with an impermeable liner and fully protective of the environment without having to move ash on the public roads,” added Faggert, who said Dominion officials are working with the DEQ to determine the proper permitting process for the dewatering.

According to a DEQ memo, one of the plant’s oldest (and mostly overgrown) ponds has a pipe that discharged stormwater runoff into Quantico Creek as recently as April of last year. Dan Genest, a Dominion spokesman, said rainwater flows across the pond and out of this pipe into the creek “just like anywhere else in the world.” He said contractors will remove coal ash from that pond, and the pipe will also be removed. The pond, which was last used to store ash in 1975, will be refilled and reseeded.

The memo said sample results from the water indicate the “presence of some trace metals typically associated with ash pond operations.”

Another Dominion spokesman, David Botkins, said, “The public’s health is not in danger.”

Some Possum Point neighbors are more troubled by the apparent politics at play than any of the recent construction work.

Surovell’s opponent, Jerry Foreman, the Republican mayor of Dumfries who lives down the street from the power plant, said Surovell’s letter is a bit of ­election-year posturing.

Danny Cosner is seen outside his home on Possum Point Road on June 27 in Dumfries, Va. Cosner has lived in this house for 38 years and said Dominion's Possum Point power station has been a good neighbor. (Kate Patterson /The Washington Post)

“What happened 50 years ago happened, we can’t control that,” said 61-year-old Danny Cosner, who has lived in his Possum Point Road home for 38 years. They’ll clean up and make it right. You’ll be able to drink their water out there after.”