Firefighters were called to a blaze at Te Maunga Transfer Station near Baypark on Friday night.
A Fire and Emergency media spokesman said three appliances were called to the Truman Lane location at 9.41pm.
A witness, who was travelling past on the way to Tauranga City, said they saw "long low clouds" coming across the main highway.
"I initially thought it must be a Baypark motorsport event until we smelt the toxic smell," the witness said.
They then saw a "large stack burning" with first responders present.
The witness then drove back past the transfer station about 12pm to see the fire was still burning and "spewing smoke low across the Bayfair area".