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.
