Pyrawall a perfect sustainable green wall solution for eroded Victorian road

Project background

An ageing road in Lavers Hill in Victoria's Otways region required major maintenance. Constructed over 50 years ago, the road had not received regular maintenance due to its low utilisation and more pressing budget constraints.

After reviewing the condition of the road, it was clear major work was required to improve drainage and prevent dangerous erosion.

The challenges

The location of the road was semi-remote, offering very limited access and single passage points throughout. Combined with an apex of around 160 degrees to work with, it presented some challenging access conditions.

To add to these challenges, the road surface was collapsing due to significant water in the area running into the bottom of the valley. The water had also caused significant erosion in the foundations supporting the road structure.

It was clear that using traditional methods was going to be very difficult, so a specialised solution was required.

Our solution

Structural stability was the key to remediating this stretch of road, yet at the same time an allowance for free drainage beneath the surface needed to be included to prevent erosion.

As a result, a mechanically stabilised earth (MSE) wall was constructed utilising a combination of Pyramat® 75 High-Performance Turf Reinforcement Mat (HPTRM) and Uniaxial Geogrid from Global Synthetics.

Due to high tensile capacity and 100 years durability, the Pyramat® 75 HPTRM was converted from being an erosion-controlling face product to a mechanically stabilised earth wall structure, by inverting the product, utilising stabilising braces and using the tails as tiebacks: a system known as Pyrawall®.

Pyrawall® is an engineered wrap-face vegetated solution used for constructing reinforced-earth walls and steepened slopes. The system consists of Pyramat® 75 High-Performance Turf Reinforcement Mat (HPTRM) and fibre-composite internal bracing. Featuring flexible setback and alignment, Pyrawall® can be customised to unique site conditions and geometrics. Over time the Pyrawall® will vegetate giving a natural wall face and offering additional stability.

Due to the width of the road, additional geogrid was used in this project to aid in stabilising the foundation. The Pyrawall® system has zero metals in the product, preventing any risk of corrosion and water pollution, whilst at the same time enabling vegetation to take root on the face, further aiding stability.

The result

After construction was completed, the result was a fully reinforced MSE wall face with additional structural stabilisation beneath the road structure, and a free-draining wall face in place to prevent additional erosion in the future. Over time the Pyrawall® will vegetate giving a natural wall face and offering additional stability.

The entire project was constructed using environmentally-friendly materials including local fill. This helped to reduce the carbon footprint by eliminating imported fill, reducing trucks on the road and ensuring waterways remained clean in this pristine natural area.