FAYETTEVILLE, Ark.—A $3 million, five-year cleanup of a former burial site for low-level radioactive waste is nearly complete, University of Arkansas officials say.

The rural Washington County site was used between 1964 and 1984 for the burial of scintillation vials—used in research experiments in which scientists measured radioactivity using photo cells to detect flashes of light.

The site contained mixed hazardous waste because chemicals and radioactive materials were buried. The site was closed in 1984 as result of the federal Resource Conservation and Recovery Act, which amended a law that dealt with the disposal of solid waste.

The university for years monitored the site, but in 2003, the school learned that the site was out of compliance with a groundwater protection standard involving the compound 1,4-dioxane. That discovery led to the cleanup, which has been paid for by one-time money set aside in the university’s budget.

The university learned in a letter May 13 that the state Health Department has signed off on the project.

“The Department has reviewed your letter and considers the decommissioning of Harmon Road site completed and closed,” wrote Jared Thompson of the department’s radiation control section. “The site is no longer considered a radioactive material burial site.”

The site has since been regraded and reseeded with grass.

“We hope to return it to general use, meaning you could farm crops on it, you could build a park on it, you could build a house on it,” said Collis Geren, the university’s vice provost for research. “And that is not farfetched, by the way: The site is totally contained.”

The university now awaits a review by the Arkansas Department of Environmental Quality, which regulates chemical disposal.

“We’ve received a report on the closure operation there, and we’re in the process of reviewing it,” ADEQ spokesman Doug Szenher told the Arkansas Democrat-Gazette. “Thus far, we’re not finding any problems.”