State environmental officials are investigating a whistleblower’s report that large drums were discovered at Bethpage Community Park decades ago during excavation work and subsequently reburied.

The site is on the state Superfund registry and is part of an $81 million mandated cleanup program to remove contaminated soils and remediate a toxic groundwater plume that has high concentrations of volatile organic chemicals, some of them carcinogenic.

Contamination there has been traced to manufacturing operations on a parcel of more than 600 acres in Bethpage used by the Navy and what now is Northrop Grumman to manufacture, test and design aircraft and space vehicles between the 1930s and mid-1990s. It was added to the Superfund list in 1983 and is subject to several cleanup programs.

Grumman Aircraft Engineering Corp. donated the community park land to Oyster Bay Town in 1962. Before that, paint, oils, chromium-tainted sludge, arsenic and solvents were dumped there — which was legal at the time.

A former DEC official with knowledge of the Superfund program said it was not illegal for drums, chemicals or other waste to be buried or dumped when Grumman owned the land. He asked not to be identified.

“It’s not atypical around industrial areas to find pockets where they used to dump stuff,” the former DEC official said.

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In the early 1990s, if workers did not see chemicals seeping from the drums when they were uncovered, there was not an obligation to report it, he said. “I don’t think it was a crime,” the former official said. “It was probably bad judgment.”

State Department of Environmental Conservation spokesman Sean Mahar said the agency “has opened an immediate investigation to ensure all waste previously disposed of at this site was addressed by the Town of Oyster Bay or is included in Northrop Grumman’s proposed remediation.”

He could not provide more details because the probe is active.

“The agency is determining whether or not the issue raised by the concerned citizen has already been identified and addressed,” Mahar added.

A field at Bethpage Community Park, on Friday April 15, 2016. Photo Credit: Newsday / Alejandra Villa

Oyster Bay spokeswoman Marta Kane said the town was unaware of the investigation. “Obviously, if this is something that is accurate, it would be a concern for us,” she said.

The Bethpage Water District reported the claim this month during a meeting with acting DEC Commissioner Basil Seggos and other state employees. The district, which serves more than 30,000 customers, has spent millions treating its drinking water to remove contaminants.

“This seems like a very credible person or resource and we passed it along to the DEC,” Bethpage Water Superintendent Mike Boufis said.

Boufis told Seggos the whistleblower said the hole was backfilled in the early 1990s after discovery of the drums.

In an interview, the whistleblower, who asked not to be named, told Newsday he had thought about the matter over the years.

Remains of a dugout at the now-closed baseball field at Bethpage Community Park, on Friday, April 15, 2016. Photo Credit: Newsday / Alejandra Villa

“I hope that what I found is relevant and it gets cleaned up,” said the whistleblower, who has property in Bethpage. “I want as much as anybody else to have it cleaned up.”

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Investigations and survey work have been done at the park over the years. Parts of it — including an ice rink, skateboard area, pool and tennis courts — are open to the public.

In 2002, the town closed down a portion of it for soil, air and groundwater tests. In 2005, a large part of the park was excavated to remove contaminants, DEC said. Additional testing was done in 2014 and 2015 as part of a cleanup plan for the park area.

Records show portions of the park also were evaluated in 1994 and 1998, and a soil survey was done when the park was first donated to Oyster Bay.

If evidence of dumping is discovered, the state can go to responsible parties and have them remediate the property, the DEC said. If they refuse, the DEC can do the work and charge for the cost.

Remains of a dugout at the now-closed baseball field at Bethpage Community Park, on Friday, April 15, 2016. Photo Credit: Newsday / Alejandra Villa

For years, water districts, the state, Navy and Northrop Grumman have tussled over how to clean up soil contamination and a series of plumes coming from the site. Officials have said the community park plume is among the most toxic.

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Late last year, a monitoring well about a mile from the park detected 14,700 parts per billion of a mixture of volatile organic chemicals, chief among them a solvent called trichloroethylene, or TCE, which is classified as a likely carcinogen. It was the highest concentration of chemicals to be documented off-site so far. The drinking water standard for TCE is 5 parts per billion.

In March, the DEC ordered Northrop Grumman to speed up construction of a remediation well, saying drinking water was threatened.

If the drums discovered in the 1990s contained chemicals, it could be a source of some of the contamination, Boufis said.

“I would think almost that is the pinnacle of the tip of the iceberg that started flowing,” he said.