GFWAust were appointed to stop the water ingress entering the completed pipejacked tunnel and shafts.
The underground cable tunnel beginning in Campbell Road, running below Burrows Road, and finishing at the Energy Australia / Transgrid Substation in Alexandria was constructed by Abergeldie.
The project features an launching shaft, an 87m long pipe-jacked tunnel and a receiving pit. The tunnel was constructed by an EPB TBM through waterlogged sand, The shafts were constructed by secant piling.
On completion of the shaft and tunnel construction GFWAust were appointed to stop the water ingress.
The secant piles were leaking at the intersection between soft and hard piles and at the intersection with the shaft floor slab. Water ingress was at a rate of about 20 litres/minute. GFWAust sealed the leaks with water stopping mortar and injection of polyurethane.
Ground water in the tunnel was ingressing at the tunnel eye where the tunnel entered the shaft through the secant piled wall. GFWAust injected polyurethane near the portal to stop the leak before injecting a precision non-shrink grout to form a permanent seal.
Water ingress was stopped allowing Abergeldie to complete the concreting works.