Tenders for a tricky 500-tonne demolition job are about to be sought by Wellington City Council.
The portico - a two-level bridge spanning the entrance to Civic Square and linking the Civic Administration Building and Wellington Central Library - has to come down because it is an earthquake risk.
Council earthquake resilience manager Neville Brown said tenders would be called in the next two or three weeks. He expected work to start in April.
The project may take up to five months. The council has budgeted $800,000 for the project, which will also involve fixing walls on both buildings, but "the tenders will tell us if we've got it right".
One challenge for the work is that the ground under the portico is a concrete slab over an underground car park, restricting the weight of cranes and equipment that could be used on the site.
The black concrete, steel and glass two-level portico, which housed a staff tea room, offices and meeting rooms, is estimated to weigh 500 tonnes "so it's not something we can cut off and drop to the ground".
There was firmer ground under the bollards at the Victoria St entrance to the Civic Centre but he expected contractors would have to take it down with small pieces being lowered about 20 metres to the ground with a light crane.
Victoria St could be obstructed during the work, but that depended on the methods used.
The portico itself was not a quake risk but the fact that it spanned two buildings affected the seismic performance of both.
"By taking it down it will allow the seismic performance of the Civic Administration Building to comply with the code."
At present it was just 25 per cent of new building standard. Taking the 500-tonne weight-off one end would lift it to 40 per cent.
The portico rested on the side of the library building, which was about 60 per cent of code, said Brown.
- The Dominion Post
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