Investigative work into the depth of the piles of the Trafalgar Centre was put on hold after a drill hit a pipe causing water to spurt two metres into the air.
The Nelson City Council decided to investigate the depth of the piles last week after much debate between council staff and opponents to the closure of the centre, Kerry Neal and Gaire Thompson.
Workers on site said they had hit a "needle in the haystack" yesterday as the pipe was only 100mm thick and the hammer on the drill was the same size.
Water shot out up to two metres into the air before it subsided.
It is understood the service line had not been highlighted to the workers. Work was expected to resume today.
A council spokeswoman said while every effort was made to avoid it, contractors sometimes accidentally broke services during excavation work.
"In some cases the services aren't in the same place as indicated on plans that contractors are working from. In all cases the damage is repaired and the work carries on as before. This will also be the case at the Trafalgar Centre and it's not considered to be a major problem at all."
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