First, the giant hole. Now, a reverse fill-in job

An estimated 5000 truckloads of dirt would be needed to fill the 12m hole on Williamson Ave, Pollen St and Crummer Rd. Photo / Steven McNicholl

New Zealand's biggest reverse civil engineering job is looming as supermarket giant Progressive Enterprises contemplates filling in Ponsonby's Soho hole.

Residents near the site said they had learned Progressive was examining the feasibility of putting the earth back up closer to street level after the cavity, equivalent to a five-level building, was excavated by over-ambitious developer Layne Kells in 2008.

Locals called the site Sohole and decried the monstrosity but Progressive has just boarded up the site's perimeter ready for next year's works, which could involve thousands of trucks rumbling into the shopping and residential area with solid fill which will then be compacted to stabilise the block.

Wade To, Brian Perry Civil's project manager who led the big dig, said the Ponsonby excavation was the country's second-largest after the SkyTower job and his largest after Britain's Pepper Hill rail tunnel in Kent.

The hole on the sloping site is at its deepest at the Williamson Ave/Ponsonby Rd corner, where it is more than 12m deep.

Luke Schepen, Progressive's national communications and public affairs manager, said a new fence replacing the wire mesh on the site served three purposes.

"Fencing has gone up to secure the site - good for safety, security and aesthetics," he said, but he could not spell out exact plans as these were still being discussed.

Progressive has already announced a Countdown store, which will be about 4000sq m and cost more than $30 million.

The site was excavated down so far to create levels for the new urban village with 1200 carparks but Countdown's new stores need only about 250 to 300 carparks.

About 40,000 cubic metres of fill might be needed. Andrew Drummond of Brian Perry said a standard truck could move about five to seven cubic metres so about 5000 truckloads would complete a job of that size.

Three years ago, Mr Drummond's firm worked with engineer Davis Langdon on the $13 million job which saw more than 100,000 cubic metres of earth removed and a 6000sq m concrete slab and underslab drainage laid.

Progressive will have to pump rainwater from the hole before work starts on the site, which is bounded by Williamson Ave, Pollen St and Crummer Rd.

SOHOLE TO NOHOLE
* Former DYC vinegar factory.
* Site of $250m failed project.
* 1.3ha site excavated five levels.
* $17m sale to Progressive in July.
* Countdown supermarket to rise.
* Work due to start next year.
* Initial work has begun.