Explosions and a huge plume of smoke emitted from a truck carrying hazardous substances that burst into flames on Auckland's Southern Motorway, on 8 March, 2023. Photo: Supplied
Papakura residents discovering oily residue on their properties after yesterday's truck explosion on the Southern Motorway are being told it is most likely canola oil.
Some items with the oily substance on them, like plants and outdoor furniture, could be washed with soapy water, but water collection tanks should be disconnected and vegetables from the garden thrown out.
A truck carrying canisters of flammable gas and other chemicals burst into flames on the Auckland motorway in the early hours of Wednesday, near Harbourside Drive.
People were evacuated from nearby homes, as explosions, smoke and debris burst from the vehicle, and chemicals spread across the road as well as into nearby properties.
In the aftermath, road workers worked overnight to repair the road, and authorities were visiting affected homeowners to offer advice.
They said an oily residue had appeared on some nearby properties, and was believed to be canola oil.
Auckland Council licensing and regulatory compliance general manager Mervyn Chetty told Morning Report they knew what some of the items on the truck were, but did not have a full list of what had been on board.
Most of these will have flashed off and burnt off with the explosion" Auckland Council's Mervyn Chetty
"I don't have a full inventory of the chemicals, but I understand that most of the chemicals being transported were flammable, including a lot of ethanol, thinners, methanol and turpentine, and most of these will have flashed off and burnt off with the explosion."
Auckland Regional Public Health Service yesterday had advised anyone affected by the smoke to contact their GP or visit the hospital if they were affected more seriously.
Chetty said anyone with a water collection tank in the area should disconnect it, and veges from the garden should be pulled up and thrown out.
"Tanks should be disconnected until the surfaces have been washed down and any contaminants removed.
"Some of the properties used grey water tanks for drinking ... rain water tanks should not be used for drinking water unless properly treated to prevent contaminants that may have fallen onto collection surfaces such as the roofs and gutterings.
"And if your vege garden has been splashed or exposed in any way it's best to avoid eating the vegetables."
Fire and Emergency and other agencies were investigating how the fire started and considering the items that were being transported.
Chetty said canisters thrown up into the air by the explosions had landed in properties.
"The main issues raised by residents yesterday [were] oily spots which cover their roofs, decking and trampolines. We visited the properties yesterday, and found that it's most likely the residues from canola oil.
"Our officers, while visiting some of the properties yesterday, did find a few cans of canola oil - the aerosol type, so ... [our advice] is to gather all of that and dispose of it."
Those who found residue on their properties should clean it off
"In terms of the spillage of the oily substance on your yards and the like - our advice is to take a precautionary approach and wash items down with soapy water. Items like decks and outdoor furniture, roofs and trampolines can all be given the soapy water treatment. We encourage the residents to check the guidance of the product in relation to the item you're washing down.
"In terms of laundry on the clothes line that may have been splashed ... we recommend rewashing your laundry and washing the clothes line."
The wreckage of the truck, after the flames were put out. Photo: RNZ / Felix Walton
Chetty said council officers were available for any residents who needed advice.
And residents considering seeking compensation for any damage could consider: "potentially a claim through their own insurance company", or "get in direct contact with the [trucking] company involved".
Transport of hazardous goods 'heavily regulated'
National Road Carriers Association chief operating officer James Smith told Morning Report the transport of hazardous goods was heavily regulated.
"There's strict requirements" National Road Carriers Association chief operating officer James Smith
"There's strict requirements regarding all aspects of the supply chain of dangerous goods, whether it's handling, loading, storage and transportation.
"There's nothing to suggest at this stage that the cause of the fire had anything to do with the load it was carrying, so until all that investigation has taken place everything is speculative."
Smith said hazardous goods were being transported throughout the country every day.
"These incidents are incredibly rare. Road transport does hundreds of millions of kilometres a year ... you're more likely to have an incident involving an electric car fire, than one of these.
"It's important to point out that just about every consignment of freight contains some components of what you would call hazardous goods ... [in] a load of groceries - cans of whipped cream are dangerous, in this case cans of canola oil used for cooking spray is dangerous.
"That's how they end up on supermarket shelves, they've got to get there by road transport."