The country's largest maternity ward at Middlemore Hospital might have to close or face major disruption because it's a seismic risk.

Photo: RNZ / Jesse Chiang

The board has just received a seismic assessment of the earthquake-prone Galbraith building, where the maternity ward is located.

But a senior manager warned the DHB's chief executive in 2012 that the building could be at risk of collapse in a one-in-2500 year earthquake.

Despite his warnings, the DHB has continued to use the building with just a small amount of remedial work carried out in the intervening six years.

The DHB's remediation plan, produced last December and just released, said the Galbraith building posed "the highest risk due to scope of potential service impacts if independent assessments confirm internal concerns".

Disruption there could extend to maternity, birthing, gynaecology, radiology, day procedures and infusion services.

On top of having nowhere else to put patients, many crucial services that support other parts of the hospital run through or under the Galbraith building.

In a statement to RNZ, acting chief executive Gloria Johnson said managers were now looking at the seismic advice and "the extent to which Galbraith should continue to be occupied in the short and medium term".

The board would be briefed in a couple of weeks, she said.

"It is unlikely that we will be able to remediate without closing or moving clinical services."

But at the moment, faced with its usual winter rush, the DHB is converting the fifth floor of the Galbraith building from offices into a ward, to take more patients.

Read Counties Manukau Health Strategic Assessment 'Facilities Remediation Programme' (PDF, 1.5MB)

Read Counties Manukau Health Strategic Assessment 'Immediate Demand Programme' (PDF 1.5MB)

The seismic assessment comes after years of debate about either strengthening or demolishing Galbraith - the hospital has strengthened a single beam and one column out of about 20 since 2012.

In emails from 2012 obtained by RNZ, then-facilities manager Greg Simpson told deputy chief executive Ron Pearson that it was not feasible to upgrade it to the extent required by its importance.

Mr Simpson quoted engineers' reports about the "danger of severe degradation" of the building's columns, that 12 to 18 beams were deficient, and in total the building had 203 structural deficiencies.

"Structural repairs (and the time taken to effect any such repairs) would far outweigh the cost of a full replacement building," Mr Simpson wrote in August 2012.

Mr Pearson replied: "However note from my understanding of this, that the block can still be used for BEDS after 2021 just not ... high acuity beds. Is that the case?"

That was the case, Mr Simpson said.

"[But] the real focus on this building should be that it will not perform well in a 1-in-2500 [year] return period quake! Especially all of the columns - read collapse!

"Personally and professionally I would not push this envelope."

Mr Pearson replied: "But if you have no choice????"

Mr Simpson then mentioned the CTV building collapse in the 2011 Christchurch quake and told Mr Pearson there was "always a choice and each has a risk".

"If we know that we have a fuse in the Galbraith - i.e. the base of every column on every floor in a 1 in 2500 RP quake, there is a pretty good chance that in such a quake it will collapse," he wrote.

"So are you saying that we have no choice and we have to use it in perpetuity with this known quantified risk?"

If the DHB was forced to continue using the building, the Health Ministry and government of the day should be made "fully aware of the situation in which we are placed".

Greg Simpson told RNZ that Galbraith's operating theatres were subsequently decommissioned, which lessened the priority to address these problems.

In 2018, the hospital faced the choice of either putting more patients into Galbraith or turning them away, and in that position he would probably do as it was doing, he said.

RNZ has been unable to reach Ron Pearson for comment.

Earthquake assessments were also now being set up for all the hospitals' other buildings as "part of normal facilities management", Dr Johnson said.

Planning documents have said the DHB was at "tipping point" and had to change its decade-long strategy of letting buildings run down in favour of funding community health initiatives to try to stem demand, which has not worked.

It had to act now, the documents said.

"A combination of accumulated maintenance and updated legislative requirements have escalated risks of seismic vulnerability in the Galbraith building; and to a lesser extent other buildings."

The costs of strengthening the Galbraith building are not known yet. A draft budget shows that just refurbishing only the first floor would cost at least $4.8 million.