Westlink M7’s stormwater system is designed to protect the environmental quality of local creeks. The stormwater system is made up of water quality basins which are storage areas with restricted outlets to slow down the passage of stormwater.
Slowing the flow ensures that natural stormwater flow patterns are imitated to minimize the impact on adjoining land and the environment.
Runoff is directed from the surface of the M7 through one of the 169 specially-constructed water quality basins. This is done to remove pollutants typically associated with motorway pavement. Water quality basins can also be used in the event of fuel or chemical spills.
Water quality basins
Water quality basins are designed to:
- capture runoff from the M7
- control sediment by detaining water for a short while, allowing silt, litter, and particulate pollutants to settle
- trap spills with lockable valves that remain open unless a fuel or chemical spill occurs. The valve can be manually closed to capture the spill which is then treated
- collect rubbish with gross pollutant traps designed to capture coarse sediment, hydrocarbons, chemical spills and large, non-biodegradable pollutants
All water quality basins are inspected and maintained regularly. Sediment and vegetation are removed if they are causing an issue. If the basin valve has been closed due to potential contamination, water is discharged as soon as appropriate treatment and testing has been conducted.
Fencing is erected around basins to restrict access for safety reasons. The fences are inspected regularly. Public access is restricted to ensure that the basins work correctly to protect the environment and control pollution.
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Stormwater system - Fact sheet (PDF 374KB)