New way to beat bridge’s acid soil

NORTH GEELONG engineering firm Austeng has designed a long-term solution to the unstable soil issues that have delayed a project to build pedestrian bridges that can survive 100 years without maintenance.

But the City of Geelong is yet to tick off on the revised plan for the foundations of the Cowies Creek bridges after testing revealed that high acidity in the soil would prevent traditional steel or concrete footings going the 100-year distance.

The tender for the innovative City of Greater Geelong initiative, hailed as the first Procurement for Innovation project to be successfully tendered in Australia, was awarded to an Austeng-led consortium about 20 months ago.

In June last year, Deakin University researchers completed design and testing for the bridge using carbon and glass fibre-reinforced geopolymer beams.

However, soil tests in October revealed the legacy of Deppeler Park’s previous uses, understood to be a tip and road-making pitch plant, required a more expensive solution than the original tender contingency.

Austeng managing director Ross George said a new design to create footings using carbon and glass fibre reinforced geopolymer — as is being used in the bridge beams — had been submitted to the council for consideration.

Mr George said the consortium would nevertheless proceed with its pouring of the first 11 carbon and glass fibre-reinforced geopolymer beam this week.

There are more than 160 council-owned pedestrian bridges in Geelong.

As part of Design Week, the City of Greater Geelong is conducting a tour of the site and a visit to Austeng to show how the age-defying bridges are being designed and made. The free event is on March 25.