Wellington Town Hall earthquake strengthening looms
Wellington's century-old Town Hall is set to get the full earthquake strengthening treatment in a two year project budgeted to cost $30 million - about $10m more than previous estimates.
Council this week advertised for expressions of interest from main contractors for work scheduled to start in July next year.
The project, which is designed to lift the earthquake rating of the 108 year old masonry building to 140 percent of new building standard, will involve a lot of expensive engineering work.
Engineers have assessed the building as being just 20-25 per cent of new building standard which means it is deemed earthquake prone.
Contractors have been advised the Town Hall was built on land reclaimed in the 19th Century and initial indications were that the building will have to be completely re-piled with substantially larger piles sunk to a greater depth than the present piles.
Council earthquake resilience manager Neville Brown said he was still awaiting expert advice on how deep the piles would have to go.
The project would involve cutting the heavy masonry building from its foundations and putting in a sub-frame to support the structure while the foundation work was done.
Once the new piles were driven the building would be placed on 150 base-isolators.
This is similar to work done on the old Parliament buildings, the Museum of City to Sea on Queens Wharf and the Old Bank Arcade on the corner of Lambton Quay and Willis St.
The Town Hall was last upgraded about 20 years ago when some minor strengthening work was done, said Brown.
That work was done under the old earthquake code conditions and Brown said council made the decision that this time it would be strengthened to the highest possible level.
That was why base isolation was chosen.
"We wanted to protect the heritage elements inside and outside the building and we didn't want to have any impact at all on the acoustic properties of the auditorium.
Alternatives would have involved constructing new shear walls and other pillars which would have an impact on heritage and acoustics.
"The additional cost of going from 100 per cent of new building standard to 140 per cent, which we get by base isolation, was minimal."
Brown said there was no intention to do another major makeover of the interior.
However, some floors would have to come out so contractors could do the repiling and this meant floors would have to be replaced.
Athfield Architects had been engaged as architectural consultants. Holmes Consulting, Opus International and Disney and Young were employed as seismic, construction and acoustic engineers.
In anticipation of the Town Hall closure council is also about to start work on a new conference and events venue in Shed 6 on Queens Wharf, next to the TSB Events Centre.
This will serve as an alternative venue while the Town Hall is out of action.
Council has budgeted $4m for that project which will involve a major interior fitout of the old wharf shed.
Brown said this was expected to take four or five months and would be completed before the Town Hall was taken out of commission in June.
The project also means council will have to find alternative accommodation to serve as the council chamber and temporary offices for the mayor and her staff.
They could move to the Civic Administration Building, The Library or the Municipal Office Building, but construction noise from the Town Hall would have to be considered before decisions were made, said Brown.
Earlier this year council also did some work on the neighbouring Municipal Office Building. About $300,000 was spent partially strengthening the building to take it out of earthquake prone status.
A full upgrade of that building, estimated to cost $10m, has been deferred for at least two years.
Council's long term plan has allocated $49m to earthquake strengthening projects over the next 10 years. This includes work on the Tawa Library and the Begonia House in the Botanic Gardens.
It has also spent about $40m on strengthening work as part of the council's 20-year $400m programme to do up all of its 2300 flats.
Brown said there were no plans to do any work on the Michael Fowler Centre, a building that was modelled on the now ruined Christchurch Town Hall.
An initial assessment of the Michael Fowler Centre indicated it was 50-60 per cent of new building standard and a more detailed assessment was planned.
For much of its life Wellington Town Hall has been identified as an earthquake risk and as recently as 40 years ago it was doomed for demolition.
The Historic Places Trust says the Michael Fowler Centre was built close to its front entrance in clear anticipation of its removal.
But a public outcry prompted the council to agree to its retention in 1983.
The grand old building - which is about to be jacked up, repiled and put on base isolators to protect it from earthquake damage - looks very different today from the original town hall.
When it was built in 1904 it was much taller and not crowded by neighbouring buildings. It was also much more elaborately decorated.
The concept of a town hall for council administration and major public events was first promoted in the 1890s.
The council set aside reclaimed land adjoining what became Jervois Quay and in 1900 the decision was made to build a town hall at an estimated cost of £50,000.
Local architect Joshua Charlesworth won a design competition and the foundation stone was laid by the Duke of York (later King George V) on June 18, 1901.
Contractors Paterson, Martin and Hunter began construction the following year and finished it in November 1904 at a cost of £68,000.
The original building had a 50m high clock tower over the main entrance, but this was taken down as a precaution after the 1931 Napier earthquake.
Some of the building's other ornate exterior decoration and grand entrance portico were also removed.
Following the 1942 earthquake, the building was strengthened and the Corinthian capitals on the exterior were removed and replaced with Tuscan detailing.
Further major changes were made in the early 1990's as part of the civic centre project. The Town Hall was refurbished and strengthened, the concert chamber and ornate ground floor toilets were demolished and the building's base on the Civic Centre side was covered over.
Over more than a century the Town Hall has hosted thousands of events. The Beatles and Rolling Stones played there and Kenny Rogers and the First Edition almost bought the house down - they played so loud part of the stage ceiling collapsed.
There were many orchestral and operatic performances, boxing matches, major political rallies, flower shows and balls. It has also served as the city's largest polling station.
- © Fairfax NZ News
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