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Wollongong City Council’s stabilising success

Award-winning Mount Keira Pass Restoration Project put to the test in recent wild weather.

Award-winning Mount Keira Pass Restoration Project put to the test in recent wild weather. Storms battering the NSW region in April put Wollongong City Council’s award-winning Mount Keira Pass restoration project to its first real test.

Wollongong City Council Senior Geotechnical Engineer Peter Tobin says that a recent visit to the site, previously plagued by rockfall and heavy rain, was proof of the project’s success.

“There wasn’t even a leaf on the road after the severe storm,” he says.

Wollongong City Council won the award for Excellence in Recycling in Stabilised Pavements in Local Government category at last year’s AustStab Annual Awards of Excellence with their Mount Keira Pass restoration project.

Mr. Tobin says the Mount Keira Pass was often troubled by rockfall and had a dangerously angled road.

After a rockfall onto the road in 2012 and a subsequent risk assessment, it was determined the council had to close the road.

By December 2013, the Wollongong City Council had put together a stabilisation project that used geotechnical techniques that hadn’t been tried before, in combination with in-situ pavement stabilisation.

The stabilisation side of the project involved recycling elements of the existing road itself.

“We had a narrow, winding mountain road with blind corners and in poor condition,” says Mr. Tobin.

“We stabilised the cliff above the road, and the embankment below, and then we got the in-situ stabilisation equipment in. We ground down what was left of the old pavement and reshaped it. It was all done on site – not one shovel of material was taken to or from the site.”

The project included roughly 500 metres of rockfall hazard reduction work, 180 metres of lower embankment anchoring and no fines concrete reconstruction, 400 metres of asphalt and spray seal works and 2100 square metres of stabilisation using a blend of lime slag.

The project was constrained as the area surrounding the site was all National Park. This meant that all work needed to be constrained within the road, says Mr. Tobin.

The works were completed in October 2014, ahead of time and at nearly half the unit cost of other mountainous pass restoration works, he adds.

The Wollongong City Council submitted the project to the AustStab 2014 Annual Awards of Excellence.

Mr. Tobin says the project stood out at the awards as pavement stabilisation was typically used in urban streets rather than in mountainous passes.

He says that the council is very proud at the success of the Mount Keira Pass restoration project and that the Wollongong public has made great use of the area.

 *Image courtesy of Wollongong City Council

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