The Vietnam Veterans Memorial in Washington. (Astrid Riecken/For The Washington Post)

The National Park Service has reached an agreement with a nonprofit veterans’ organization to take custody of cremated remains left at the Vietnam Veterans Memorial and bury them with honors at a private in-ground vault in Virginia.

The Missing in America Project will take possession of the 80 sets of cremains that have been left at the memorial through the years, as well as any future cremains that are left, the Park Service said in a statement.

They will be inurned with full military honors at an in-ground vault at a private cemetery in Manassas, the statement said.

The purpose of the MIA Project is to locate, identify and inter with dignity the unclaimed cremated remains of American veterans, according to the organization’s website.

Leaving mementos at the memorial’s Wall has been a tradition since the polished stone landmark bearing the names of the 58,000 Vietnam War dead was dedicated in 1982.

Hundreds of thousands of letters, photographs, jungle boots, stuffed animals, sculptures, dog tags, college rings, a motorcycle, cigars, a piece of a helicopter rotor blade and human remains have been left.

The artifacts are gathered and stored in the Park Service’s large Museum Resource Center in suburban Maryland.

Human remains have also been left, sometimes at the behest of the deceased or a family member. The cremains — some in containers, some scattered — have been left since 1990, officials said.

Four were left there over the Memorial Day weekend.

In the fall, the Park Service placed signs at the Wall asking people not to leave human remains.

“We’re not really equipped,” Laura Anderson, curator for the Mall and Memorial Parks, said in January. “I imagine it’s a big decision — what do you do with your loved one — especially if somebody is asking to be left here. You want to honor those wishes. But we’re not allowed to accept them.”

The human cremains were kept in a locked metal cabinet with the windows papered over at the resource center. No date for the transfer or burial has been set, the Park Service said.

Brigitte Corbin, of the MIA Project, said the remains will be kept in their original containers and placed together in a vacant, spacious underground vault that has been donated by the cemetery. She declined, for now, to identify the cemetery.

She said any relatives who don’t approve of the move can contact her and pick up the remains.

Mike Litterst, a Park Service spokesman, said: “It’s a decades-old problem that we’re very pleased to have a solution for.”