On the Southern Expressway a number of temporary and permanent water protection measures were used to reduce the impact of construction activities and the impact of road runoff water on local waterways once the expressway was operational.

During construction:
soil erosion and drainage management measures for the site were documented in the Environmental Management Implementation Plan and the regular site reports
treatment measures, including sediment basins, silt fences and cut-off drains were installed to assist in the collection of sediment prior to the discharge of stormwater from the site
water quality monitoring was undertaken to monitor any sediment discharge from the site.

A range of permanent water quality treatment measures have been implemented to treat pollution from operation of the road, including wet detention basins and wetlands.

Water quality monitoring undertaken to determine the effectiveness of the detention basins has indicated the following water quality improvements:

Parameter % Reduction
Cadmium -
Copper -
Lead 77
Nickel 55
Zinc 61
Total Suspended Solids 56
Total Dissolved Solids 18
Total Nitrogen 64
Total Phosphate 77

Reference: University of SA (2000) An environmental investigation to assess the effectiveness of stormwater detention basins in improving water runoff for Transport SA.