Wattle Flat water main finds home among the gum trees

Innovative thinking and proactive environmental management have ensured 137 of Main South Road’s iconic native gum trees continue to thrive, while still enabling improved water services for the Fleurieu Peninsula, as part of a recent three-kilometre water main upgrade at Wattle Flat.

Prior to laying the new water main, an independent arborist performed a comprehensive tree assessment to understand the health and vitality of the Blue Gum, River Red Gum and Pink Gum trees lining the edge of Main South Road, informing SA Water’s individual assessments of each tree’s root system.

SA Water’s General Manager of Sustainable Infrastructure Amanda Lewry said the team designed a bespoke ‘dig with care’ construction methodology, balancing the upgrade with protecting the natural environment.

“Standing at around 15 metres, the beautiful gum trees are an integral part of this stretch of Main South Road and I’m proud of our team’s initiative to preserve the trees’ wellbeing while delivering a vital piece of new infrastructure for the local community,” Amanda said.

“The proximity of the planned pipeline route to the established gum trees presented a real challenge, but also encouraged fresh thinking from our team and our construction partner, John Holland Guidera O’Connor joint venture.

“Informed by the arborist’s assessment and harnessing our people’s experience working in tree protection zones, we adopted a range of trenching techniques depending on the root interactions for each individual tree, using hydrovac excavation to identify high-risk root systems.

“Hydrovac excavation – which uses high-pressure water to loosen soil before removing it through an industrial vacuum – is a non-invasive technique that enabled our crews at Wattle Flat to safely determine the likely distribution of roots.

“For areas of high tree density, specifically around creeks, we employed horizontal directional drilling to tunnel under the tree roots and pull the new pipe through, avoiding the roots completely and keeping them intact.

“Exploring different construction methodologies is a practical example of our commitment to preserving the environment and this outcome has helped ensure the trees remain healthy and continue to be there for many years to come.”

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