Increasing demand for aggregates as a result of the transport infrastructure and housing boom in Melbourne prompted our client, Hanson — a leader in building and construction materials — to expand its current quarrying operations in Wollert, a residential growth area north of Melbourne. This expansion, however, required diversion of two natural waterways that formed part of the Findon Creek network.
It was vital that the realignment of these waterways maintained existing habitats and promoted new habitats for fish and other fauna, particularly the endangered growling grass frog. It was also extremely important to protect and maintain indigenous trees on site, as well as ensuring no adverse impacts on stormwater conveyance, catchment flood storage and water quality. The realignments also had to consider a VicRoads Public Acquisition Overlay for a significant section of future roadway.
Golder worked with Hanson, Melbourne Water, City of Whittlesea Council and other stakeholders, including VicRoads and the Department of Environment, Land, Water and Planning to produce a sustainable design solution. Golder’s role encompassed design, project management and construction supervision of the creek realignments, provision of habitats for aquatic fauna, and upgrade of a downstream culvert to provide a better connection between the realigned section of the tributary to Findon Creek and its downstream reaches.
Sustainable development was at the heart of the project both in terms of providing a supply of locally sourced building materials to local projects while also sustaining the capacity for the realigned waterways to provide adequate current and future water quantity and quality management as well as promoting flora and fauna biodiversity.
The realigned waterways have a combined length of approximately 1.5 km and were sized to manage the 100-year flood with flexibility to incorporate water above this level. Sedimentation settling zones were incorporated through wider and flatter channels at the downstream ends.
Riffles, fish ladders and fish pools were incorporated into the waterways to enable fish to migrate up the waterways and rest while undertaking this journey. Two ponds were designed to encourage growling grass frogs. These features, along with the planting of native vegetation and a comprehensive weed management program, are expected to support and encourage improvement of the health of the existing ecosystem.
The native species planted within and around the waterways will enhance visual amenity while the quarry is operating and will enable the site to be transformed into an appealing public space when the quarry is decommissioned.
This project went beyond fulfilling the client’s commercial goals by also enhancing sustainability through protecting local fauna, managing and improving water quantity and quality, enhancing local amenity, and incorporating climate-resilient design.
It is an exemplar of how to plan, manage and integrate waterways into similar sites and demonstrates how commercial operations that embrace sustainable design can not only protect sensitive environments but even improve on existing conditions.
This project was a finalist in the 2019 Stormwater Victoria Awards for Excellence in the category “Excellence in Integrated Stormwater Design”.