The man linked to the toxic West Footscray warehouse that erupted in flames last year has illegally buried 50 million litres of chemical waste on farmland in western Victoria, threatening the water supply for the Wimmera district.
The stockpile is buried on land owned by Graham Leslie White, who is currently in prison for serious firearms offences and has been linked to at least nine other chemical dump sites uncovered in warehouses in Melbourne's north.
The underground stash, 15 kilometres from the town of Kaniva, is suspected to contain more than twice the amount of toxic waste already seized by authorities investigating what is the biggest illicit dumping operation in the state's history.
The Age can reveal the land is next door to farms producing a huge quantity of agricultural products for the Melbourne market, and a national park.
The stash of waste is contained in steel drums and plastic containers entombed in trenches and pits just 60 metres above a water table that is used to irrigate farms and supplies the water for communities near the border of Victoria and South Australia.
The Environment Protection Authority said extensive testing at the Kaniva property had so far found no contamination in the water, soil or air.
"EPA's first priority has been to ensure neighbouring properties and the local Kaniva community are not at risk," chief executive Dr Cathy Wilkinson said.
But the EPA has kept the existence of the illicit dump site secret from Wimmera locals for nearly a year, and the regulator only recently began notifying individuals nearby about the threat of contamination to their crops.
"They contacted me two to three months ago to tell me they were investigating a property near mine where they found someone was dumping 'products' illegally," one local farmer said.
"They didn't mention the type of product. [And] three weeks ago they said they wanted to do some water tests and compare the results with our historical [water and soil testing] data."
A number of Kaniva locals told The Age that reports of recent activity at the seemingly abandoned bush block, and the appearance of EPA officials in town had been fuelling speculation in the information vacuum.
"We don't know anything really beyond the rumours. We've heard there's chemicals buried out there but nobody knows much more than that," said Bob Bone of Bones Butchery in Kaniva.
"I just hope it doesn't get into the water table. Our water table is our water supply here."
An EPA drone specially equipped with ground penetrating radar identified 20 suspected dump sites on the sprawling bush block, with the waste buried four metres in the earth and spread over an area totalling three acres.
"This is a 1,400 acre property and to locate the illegally buried material across such a vast area was like looking for a needle in a hay stack," Dr Wilkinson said.
"The size of the dump sites varies and getting an accurate assessment of the final quantity and exact nature of the contents of the underground containers is going to take more work."
"Local bores have been tested in the flow direction of the water on several occasions and show no groundwater contamination off site."
The water system in Kaniva is part of the Murray Darling Basin, which is one of the country's most important agricultural regions and produces a third of Australia's food supply.
Hydro-geologist Dr Wendy Timms would not comment on White's property specifically, but said the impact of a chemical leak into Kaniva's groundwater system could potentially pose serious consequences for the region.
The level of risk to the water table will largely be determined by the classification of the soil and the conditions of the barrel, according to Dr Timms. But any contamination of the groundwater will be difficult to manage if not treated early.
"Water underground travels through soils and aquifers that is very slow flowing," Dr Timms said.
"Fortunately if a leak does get into the soil and groundwater it's not going to go anywhere fast because things are slow. However, the consequence of that is if it does get in and work is not done early enough ... it will take a very long time to clean up."
The EPA has declined to comment on the volume of chemicals it estimates on site, except to say they represent a "significant amount".
The Country Fire Authority said it was "aware of some chemicals being stored" outside Kaniva.
"Vapour testing has been conducted and shows that the risk of the materials igniting is very low," a spokeswoman said.
The EPA is planning to hold is first public information session in Kaniva on July 30.
David Leahy, chief executive of the West Wimmera Shire, declined to comment publicly on the situation except to say the EPA was keeping them informed.
The contents and condition of the steel drums and plastic containers are unknown as the EPA has not uncovered the burial sites due to the risk of ruptures or spills.
But removal operations run by WorkSafe at White's other dump sites in Campbellfield and Epping, on Melbourne's outskirts, found solvents, inks, paints, detergents, aerosols and cleaning chemicals often housed in broken or rusted containers that were leaking. The cost of cleaning up those warehouses alone could reach $50 million.
The EPA is continuing to closely monitor the groundwater around the Kaniva property and intends to issue "clean up" notices to White when he is released from prison in September after serving six months jail.
The 58-year-old was convicted over a haul of illegal weapons, including a machine gun, uncovered at his Dracula-themed Wallan home during a police raid last year.
"There will be several clean up and site management options and at this stage, nothing is off the table so long as it guarantees the ongoing safety of the environment and the community," Dr Wilkinson said.
The possibility of compelling White to clean up the stockpiles has already been attempted and discarded by dangerous goods regulator WorkSafe, which seized control of the sites in Campbellfield and Epping to prevent worsening risk to human and environmental safety.
White's assets, including the proceeds of the sale of $2.6 million in properties, were frozen by order of the Supreme Court after he failed to pay a clean up bill issued by WorkSafe for just one of his nine warehouses.