Wanaka pool could collapse, says report

23:40, Jul 23 2014

A building report says the Wanaka pool is potentially life-threatening and could collapse because of critical structural weaknesses.

The Queenstown Lakes District Council yesterday released two reports it had commissioned into the seismic capacity of the pool building that it closed last week.

Holmes Consulting Group completed both reports, which are now being peer reviewed.

The reports say interior concrete masonry blocks were not reinforced and connections in the roof had insufficient load-transferring strength.

The pool complex was designed in 1991 by Anthony Major, who was also the design engineer behind Stadium Southland.

This month Major was expelled from the Institute of Professional Engineers of New Zealand for breaching its code of ethics for his work relating to the stadium, which collapsed in September 2010 after a heavy snowfall.


Major declined to comment yesterday.

The reports into the Wanaka building say Wanaka is in one of the higher seismic-risk regions, where reasonably severe ground shaking was possible, and "critical structural weaknesses" raised the possibility of roof collapse.

The report says the standards used for engineering in the early 1990s were 41 per cent of the current specifications for structural integrity.

Timber within the roof cavity had severe moisture buildup, daylight was visible from inside through a large crack in a masonry wall and a timber roof purlin in original drawings was missing.

The independent engineers calculated the building met 20 per cent of earthquake standards. The reports by Holmes engineers Christopher Wooding and John Trowsdale were based on original drawings and a structural assessment done last month.

Council general manager Ruth Stokes said the pool was built for Mount Aspiring College and the council started management of the pool in 2010 and had legally owned it since last year. The council sought legal advice before deciding to close the pool this month.

Staff were investigating options and costs to strengthen the building, she said.


Critical structural weaknesses identified by the reports:

Connections from the roof to the masonry walls – known as "load paths" – had insufficient capacity. "This has the potential to lead to a structural collapse of the main roof structure."

Interior block walls do not have the ability to support their weight in a large earthquake. Walls could collapse. "The failure of these walls presents a direct life safety hazard."

Frames were unlikely to withstand a 1-in-150-year snowfall. Failure would be sudden, leading to collapse of the pool roof. 

The Southland Times