Developers building the $850 million Transmission Gully motorway project, north of Wellington, have underestimated the amount of earthworks required by 50 percent.
Construction at the Transmission Gully site. Photo: Supplied
The Wellington Gateway Partnership is seeking new resource consents for an extra three million cubic metres of earthworks, bringing the total to nine million to build the 27km motorway between Mackays Crossing and Linden.
The consortium's chief executive Sergio Mejia said it was working with councils and the New Zealand Transport Agency to ensure the road was still on track to open in April 2020.
"It's not unusual for volume increases of this scale once detailed design and specifications are finalised," he said.
"It is common for contractors to need to seek additional consents to account for those changes in scope."
The additional consents cost about $50,000.
Three-quarters of the consents required from 20 regional council consents are needed, plus associated local council approvals, have already been approved.
There would be "no impact" on the total project cost, Mr Mejia said.