Nelson's Trafalgar Centre could be salvaged, depending on a review under way of government rules related to earthquake prone buildings, and health and safety regulations.
Nelson Mayor Rachel Reese said the council was awaiting further information to decide to what degree the centre has to be strengthened and the cost.
Legislation on buildings and earthquake-prone buildings, and health and safety were under review, which would give greater clarity on strengthening requirements, Ms Reese said.
The city's main civic venue, now classified as an earthquake prone building because its seismic rating falls well below current building standards, was shut earlier this month. Engineering and legal advice identified that if the centre was in use during a moderate earthquake the risk of loss of life would be high. Special consideration was also needed because the Trafalgar Centre was designated a post-disaster evacuation and welfare centre.
Closure of the Nelson School of Music followed, leaving Nelson temporarily without a main concert venue, but a plan for earthquake strengthening the historic building was already well under way.
Closure of the building, and the relocation of staff, had happened sooner than planned, board chairman Neil Deans said last week.
The risk of a building collapsing in a serious earthquake presents significant challenges for employers, building owners and tenants, a legal report said.
The Trafalgar Centre's recently upgraded southern end was classified as being 25-30 per cent of the new building standard [NBS], the main section, 20-25 per cent and the northern end is 15 per cent of the NBS.
A report by Tonkin and Taylor concluded that the risk of liquefaction was "very significant" because of the nature of the soils beneath the building.
Ms Reese said liquefaction issues were highlighted by a geotech report drawn up when the council began exploring options for the planned upgrade to the Trafalgar Centre's northern end.
Paul Brimer, director of Dunning Thornton Consultants, which formed part of the Trafalgar Centre seismic evaluation peer review, said damage "must be expected during moderate seismic events" to any linking claddings, linings, services or structure that connected the separate parts of the Trafalgar Centre. It was recommended that the robustness of the structures was considered of prime importance rather than solely the percentage NBS rating.
Ms Reese said the council's chief executive, Clare Hadley, had been directed to start a review of issues around the southern extension, completed in 2009, and to seek more information in relation to the council's obligations under the Building (Earthquake-prone Buildings) Amendment Bill, Health and Safety Act and Occupiers Liability Act.
"These are fast-changing times. We will have greater clarity on strengthening requirements in the new year and it is very important that we take a considered approach to what happens next, given the significant financial implications," Ms Reese said.
She said the advice the council received on shutting the building was quite clear, and that closure was the appropriate course of action.
However, fixing it could be less onerous, depending on what amendments might be made to current rules.
"If the expert view is that 34 per cent [of the NBS] is applicable alongside the other legislation that will have a big difference to how we approach the Trafalgar Centre."
Ms Reese said the cost difference between bringing the building up to that standard, and bringing it up to a 67 per cent rating that is required now, would be massively different.
"If we want to address liquefaction alone that could put the figure up to $30m or more just to create a platform so we could have a building that would perform without significant damage.
"In the end it's about assessing what degree of risk can we live with."
Ms Reese said she was not feeling panicked by the situation.
"Once we get the information back we'll have more certainty over the next steps."
The closure of the Trafalgar Centre and the Nelson School of Music had re-ignited discussion on the performing arts centre, but it was important not to confuse the two, she said.
The timing around closure of the two buildings was coincidence. "It's time to step back and be confident that the decisions we made were in accordance with the best information at the time," Ms Reese said.
She added there was no indication on which buildings might follow.
"At the moment there are steps to follow and opportunities for councillors to ask questions in relation to technical and legal matters.
"I'm not aware of any others facing imminent closure."
The council had already closed a few of its own buildings, including the State Advances Building, the entrance to the Riverside Pool which was undergoing strengthening works, and the Hub building in New St, which was to be demolished.
It has also issued notices on a number of privately owned buildings in the city, which have to be strengthened or demolished by various deadlines, depending on a building's level of vulnerability in an earthquake.
- © Fairfax NZ News
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