The job of maintaining and upgrading local roads, bridges and waterways is a constant challenge for local Councils, a balance between delivering good services for their community while working within budgets and timeframes.
Recently, MidCoast Council in NSW presented an innovative solution at the 2017 Association of Public Authority Surveyors NSW conference where they have used polystyrene waffle pods in a world’s first culvert construction method.
Taking the inspiration from the residential building sector where waffle pods have been used for many years, their use in the tunnel that carries the stream underneath the Belbora Creek Road, north off The Bucketts Way between Taree and Gloucester delivered dramatic cost saving, cutting the $400,000 budgeted cost of the works to $186,000.1
Grant Calvin is a senior survey designer with MidCoast Council. His paper on this project, “Building a Bridge with a House Slab” saw him recently awarded the Keith Haddon Award. He wants other councils to know about the innovation and says “we’ve improved the level of service, done it in a sustainable way, it’s cost effective. Those are the catch phrases that are thrown around local government and we ticked them off.”
“The waffle pod system provided a quick, cost-effective method to install a low-level bridge, or culvert over the existing concrete causeway. This method maintained and built upon the existing infrastructure, provided a higher level of service to the road and in this instance preserved significant aquatic habitat and irrigation access upstream of the structure,” his paper concluded.
Carey Molloy from Matrix Thornton Consulting Engineers was part of the team challenged to come up with a solution for the culvert that could deliver significant improvements for the waterways and the budget. He says the team came up with 20 different options but it was waffle pod technology, developed for residential concrete house slabs, that ticked the right boxes.
“It was bloody obvious really,” Carey said. “Waffle pods came out on top in the cost benefit analysis and we reuse them after you dig them out.”
The use of waffle pods in the design not only allows rapid low-cost construction and meets rigorous local government structural requirements, it allowed for the existing causeway to remain place, reusing the existing infrastructure and minimising creek bed disturbance.
Foamex Diamond Pods are a strong yet lightweight polystyrene waffle pod void former system for concrete slabs. Foamex Diamond Pods provide under slab insulation and support, while reducing the effects of soil movement, and lowering the amount of concrete required for a build.