Papua New Guinea's Chinese-run Ramu nickel mine is the subject of criticism over potential environmental problems caused by the slurry waste pipeline's proximity to a major highway.
The 134 kilometre pipe is being built from the mine site southwest of province's capital Madang to a tailings dam and wharf in Basamuk Bay.
One of PNG's leading engineers Professor Simon Saulei has told the newspaper, The National, that he's concerned there was no consultation before the construction began.
Mr Saulei says the pipeline doesn't have proper foundations, was constructed just metres above waterways, cuts through villages and is simply too close to the highway.
Locals reportedly fear an environmental disaster is waiting to happen as during production the company plans to pump 100 million tonnes of what it calls neutralised slurry waste into a deep sea canyon in the bay.