The Rena owners and insurers have been accused of sending mixed messages about the safety of leaving the wreck on Astrolabe Reef.
Tauranga Mayor Stuart Crosby made the accusation during a briefing of the city council yesterday by Beca consultant Keith Frentz.
The resource consent application to abandon the wreck was expected to be lodged by early next month.
Mr Crosby said he was receiving mixed messages. The council was being assured the wreck would be safe if left on the reef, but on the other hand it was being told the bow section would continue to fall to bits.
"What is the real prognosis for the wreck?"
Mr Crosby also sought an assurance there would be independent reviews of all the scientific evidence in the consent application. He wondered whether there would be enough time in the two months for public submissions for an expert analyse of the application.
Mr Frentz responded that the wreck would continue to degrade to a "lower energy state".
The bow had broken into seven pieces. However, the two things of most concern, the TBT contaminants in old layers of anti-fouling paint and copper cloves, were not in the bow section.
The marine contractor for the ship's owners and insurer Captain Roger King explained the rate of degradation depended on the depth and situation of the wreck on the reef. He said the aft section was relatively stable in deeper waters whereas the bow was in a high-impact area with swells.
Seven hundred tonnes had been removed from the wreck's debris field and the focus was now on removing snagging hazards like rolls of wire. Sharp pieces protruding from the wreck would also be removed.
Mr Frentz said there had been a lot of discussions about redress with iwi groups, with Maketu suggesting there should be a marine studies institute established in the town. "This could form part of the solution."
He described Motiti as an "interesting place" to consult. Five different groups had different opinions, with no agreement so far on what could be achieved.
Mr Frentz said full removal of the wreck of the Rena would set back the environmental recovery of the reef by five to 10 years. Cutting up the hull would scatter TBT paint particles whereas if the wreck stayed in place the hull would become sealed by marine growth.
"Assessments show removal effects could be more significant than leaving it there," he said.
He said the best scenario to remove the entire hull would be five years, but it could take 10 years. Worker health and safety considerations from working at depths of up to 65m also had to be taken into account, Mr Frentz said.