Work crews begin to rip up and replace 4-kilometres of concrete on the Sapphire to Woolgoolga Pacific Hwy upgrade.

Work crews begin to rip up and replace 4-kilometres of concrete on the Sapphire to Woolgoolga Pacific Hwy upgrade. Trevor Veale

THE consortium building the Sapphire to Woolgoolga Pacific Highway upgrade, Leighton Fulton Hogan, will wear the cost of a bungled concrete pour spanning 4km of freshly laid pavement.

The State Government has confirmed that air pockets were found under the surface of the concrete section near Arrawarra, which spans 1m in width.

Engineers and work crews discovered the problem as stabilising bars were installed.

Member for Coffs Harbour, Andrew Fraser, confirmed the contractor Leighton Fulton Hogan would pay to replace the faulty concrete section, which is currently been dug up.

"Quality control checks identified there were air pockets in the concrete, and luckily it was found now and not in six month's time," Mr Fraser said.

He said the problem would delay the opening of the Arrawarra interchange, but was not expected to impact on the upgrade's overall expected completion date in the second half of next year.

The 25km Pacific Highway upgrade that started in 2010 at a projected cost of $700million is now projected to cost $850million.