GAUTRAIN FOR CLEAN WATER

Rivers in Gauteng are already highly polluted due to urbanisation. By purifying water collected during the excavation of tunnels, Gautrain takes extra care to protect our natural resources from pollution.

During the tunnelling process, ground water naturally seeps into excavated areas. Here the water becomes polluted as it is exposed to tunnelling processes like drilling, the use of explosives and shotcreting – the spraying of concrete.

Strategically placed pumps siphon muddy water from inside the tunnels. The water is then pumped to the surface pre-settling ponds for the silt or mud to settle.

Leaving the pre-settling ponds, water contains less silt. It is pumped into the water treatment plant. Here it undergoes treatment processes such as acid dosing to reduce the high alkaline or ph levels caused by exposure to tunnel construction processes.

Daily monitoring and monthly sampling of water treatment plants is done on continuous basis on sites, and samples are sent to independent laboratories for testing. This is to ensure that the water is clean as per standards set out in the water use licence issued by the Department of Water Affairs and Forestry.

Clean water is either released into the environment via storm water drains or re-used on construction sites. Typically, water will be used to spray dusty construction sites, washing mud off construction vehicle wheels or cleaning cement trucks.

The removal of water during tunnelling is also important for safety reasons. Construction workers and vehicles cannot proceed in muddy conditions. During drilling and blasting, heavy construction vehicles have to remove excavated rock from tunnels and therefore a relatively dry environment is required.

The lengthy process of collecting and cleaning water during tunnelling is required in terms of Gautrain’s Environmental Management Plan. It ensures that communities and the receiving environment are not harmed during the construction of Gautrain.