It was more than just a stroll down memory lane for Al White.

When the retired military police sergeant returned to Base Gagetown in New Brunswick last week, he brought with him the memory and the burden of friends lost to the ravages of time and cancer.

On Thursday, he also led scientists and environmental engineers from National Defence on a damp trek directly to the spot where he claims dozens of barrels containing the notorious defoliant Agent Orange were secretly buried over three decades ago.

The location was not among the contaminated sites flagged by the military in the six decades since the base was established.

"It's good," White told CBC News. "I'm glad to be here to do this and bring some form of closure."

White claims that, in the late spring of 1985, he escorted a flatbed truck loaded with chemical barrels to a point near the base's tank training range, where they were buried in a large hole near an area known as the Shirley Road dump.

It happened before sunrise and White said he'd always found it suspicious. He kept silent, however, until he lost three friends — all former Gagetown soldiers — to cancer.

The speed and confidence with which he pointed out the site impressed defence officials, including the base's chief of environment services, a geophysicist and a environmental engineer.

"Pretty darn precise," said Pam Cushing, senior project manager with the National Defence Directorate of Contaminated Sites.

Cushing and White used maps and aerial photos of the area, wrapped in plastic against the rain, to confirm his recollection.

'A very vivid recollection'

The site he pointed out is just off a road junction leading to the training grounds. The uneven growth of the vegetation over the site caught the eye of Saleem Sattar, the department's director general of environment and sustainable management.

"You'll note there are taller trees over there and shorter here," he said. "So there was some activity. So we'll be able to look into it."

It will be months before geophysicists are able to confirm precisely what — if anything — lies beneath the tangled brush and thorny ground.

Sattar said White has proven to be a highly credible witness.

"He has a very vivid recollection of that activity from 30 years ago," he said. "The fact that he recalls precisely the road we have entered here on, and the fact he pointed out where a truck carrying barrels may have come in and unloaded some of those barrels ... he has a tremendous recollection that we need to verify."

Still, DND officials dispute the core of White's claim — that barrels buried at the site may have contained Agent Orange, which was used by the U.S. military in two separate sets of aerial spraying tests at the base in the late 1960s.

The defoliant, which was widely used during the Vietnam war, has been linked to various cancers by health experts.

There are four known burial sites at Gagetown containing drums of various chemicals, even asbestos waste. Those sites — some near wetlands — are capped with fresh soil and monitored for contaminated runoff.

National Defence has received reports of 11 other possible burial sites over the years — none of which the department has confirmed as accurate.

"We've never found any evidence of Agent Orange coming out of those areas," said Sattar.

"That being said, we are open to the possibility that there might be something out there. And that's really the reason we've asked Mr. White to come out today ... to help us rule out that possibility."

He said that, to the best of the department's knowledge, "all the residual or remaining stock from those [Agent Orange] tests were taken back to the U.S. on the same trucks they came in on."

The evidence defence officials offered to support that version of events was provided to CBC News during a background briefing: a press release issued by the military in 1985, around the same time White claims he witnessed the secret burial.

The defence department, in a statement late Tuesday, said it was at a loss to explain why a burial would have taken place at the hour White alleged.

"It is not clear why a disposal activity might have taken place in the early morning hours," said the statement. "While in the early- to mid- 1980s, the accepted environmental practice was for barrels to be perforated, triple rinsed and crushed prior to disposal as regular waste."

White stood by his version of events, saying he was told by a superior what was in the barrels and that some of the drums were marked with an orange stripe indicating they contained the defoliant.

"I know what I did and — like I said, time and time again — I will point it out," he said.

"It was 30 years ago. If something is there, that eliminates one more site."

Sattar said that, if something does turn out to be buried at the location, it might be barrels of herbicide.

Officials tagged the location using GPS. The next step in the investigation will see searchers deploy equipment to detect magnetic anomalies. If they find evidence of metal buried underground, they'll come back and dig up the site.

A history of chemical use

Some local residents have fought for years to get the federal government to acknowledge the long history of chemical spraying at Base Gagetown. They say they're pleased the issue is back in the public spotlight.

Regardless of what the DND follow-up investigation reveals, Carol Brown-Parker of the Agent Orange Association said White's allegations have served to remind people of the military's years of chemical use on the base, and the resulting contamination of the soil.

She said she has no doubt that the military's decades of chemical herbicide spray programs are linked to local cancer rates and other health issues.

Brown-Parker said she remembers walking to school as a child in the 1960s near the village of Enniskillen, 64 kilometres south of Fredericton — remembers how the grass would be green one day and dead the next.

"It was all brown and crunchy underneath my feet," she said, "and I wondered, 'How could that happen?'"

Al White leads soldiers and DND scientists to the alleged burial site. (Murray Brewster/CBC News)

What Brown-Parker likely witnessed was the aftermath of one of three so-called 'spray drift' incidents which National Defence has publicly acknowledged. Chemical clouds meant to kill vegetation on base property were inadvertently blown onto nearby land and communities in 1964, 1972 and 1988.

Property owners were compensated for those spray drift incidents. The federal government paid out over $96 million to ex-soldiers exposed to U.S military Agent Orange tests that took place in the 1960s.

Area residents have long complained about cancer and other illnesses they attribute to decades of herbicide spraying on the base, including the Agent Orange tests. They say no one has claimed responsibility for what happened to them.

"I'd like an apology from our prime minister," Brown-Parker said. "It's not his fault, but all the prime ministers before him knew. The government knew what they were doing. They knew they were spraying harmful chemicals."

Defence officials would not address her claims. Sattar said that he believes a report written in the early 2000s by former New Brunswick health minister Dennis Furlong "definitely" addressed the health risks.

That report concluded the annual spray program "posed no long-term risk to human health and safety."