Tunnelling is of high importance for cities to integrate road and public transport networks. Upgrading and linking major roads eases congestion and increases transportation options.
Tunnels deep below ground can have minimal impact on the surface above. During construction of tunnels, cars use existing roads and residents who live nearby have minimal disruption.
After construction, water accumulates within the tunnel from groundwater sources interrupted by the excavations. The ground water can look very clean but contains high quantities of natural impurities and in some instances man-made pollutants that are a legacy from past industrial activities at the surface. Iron that is dissolved in the groundwater when it is underground will precipitate when the water meets air, changing the water from clear to muddy red.
Tunnel effluent collected in the tunnel drainage system consists of groundwater, wash water and run-off. The effluent needs to be treated to meet the adopted water quality trigger values consistent with the ANZECC guidelines required for discharge into the nearby receiving waters.
Two groundwater treatment plants have recently been commissioned for two new NSW road tunnels, and one for a third tunnel is underway. Because the groundwater discharges into different receiving waters a different setup is required for each. All three require primary treatment which includes:
These plants were also designed to accommodate stormwater, deluge test water, fire water and tunnel wash-down water.
The solids that are removed by the HyDAF in the form of a liquid slurry is dewatered to a spadeable cake to minimise the costs of disposal.
Simplified process schematic
“Hydroflux are really proud of their contribution to these projects and offer a big thank to you to all involved for all the hard work and effort put in this project.”
About the Hydroflux Group
The Hydroflux Group comprises eleven companies based in Australia, New Zealand, the Pacific, and the UK, providing design and build, equipment, processes and operational services in water and wastewater treatment. Hydroflux Industrial specialises in industrial wastewater treatment including designing and constructing plants and supplying equipment across all sectors. Hydroflux Industrial is a member of the Hydroflux Group.
Hydroflux Industrial Pty Ltd
Level 26, 44 Market St. Sydney NSW 2000 Australia
P +61 2 9089 8833 F +61 2 9089 8830