The state's environmental watchdog is seriously concerned about Port Kembla Copper's revised proposal for the felling of its iconic copper stack.
PKC last month sought approval to use a specialised crushing device to remove the 200-metre-high stack bit by bit, rather than the previously approved controlled explosive demolition.
PKC claims the new method would minimise noise, vibration and dust emissions, and would pose fewer safety risks for nearby residents.
However, the NSW Environmental Protection Authority said there was insufficient information in PKC's application to assess the possible environmental impacts and determine whether the method was safe.
Among the authority's concerns are the possibility of large concrete pieces falling from the stack during the crushing process, and whether they could carry beyond the exclusion zone.
"The stack is located about 100 metres from a main road, residential areas and a preschool," an EPA submission on the revised method warned.
The EPA also said PKC had failed to consider how strong winds might effect the falling pieces: "Moderate to strong winds are common in the area and can vary seasonally. The EA [environmental assessment] does not appear to consider the wind conditions under which the crushing operations can be satisfactorily carried out without resulting in an off-site impact."
The EPA has recommended NSW Planning seek an independent review of the demolition proposal "by a suitably qualified expert" before a decision is made.
The authority also questioned why other methods were not assessed as part of the application.
They suggested top-down segmenting, where sections of the structure are sawed individually with a diamond blade and removed piece by piece, or partial demolition to remove the upper sections only.
The latter could preserve at least the lower section of the stack, resulting in "a structure that can be more easily maintained, converted to some beneficial use and [therefore] better promote its recognised heritage values".
The Port Kembla Pollution Committee, representing Port Kembla residents, also lodged its objection to PKC's proposal.
The group said residents, who would have to contend with effects of the demolition for 11 hours a day for more than four months, were concerned about safety, air quality and noise.
"Constant and daily monitoring of air and noise should be part of the conditions of consent," the group wrote.
PKC is expected to respond soon.