The Bowline is an iconic 16-story apartment development located in the Wickham suburb of Newcastle, Australia. There is a secant pile constructed wall system in the basement of this new building. However, an issue arose during the drilling process, where the overlaps were not interlocked correctly, resulting in voids and substantial leaks. This situation posed a risk of sinkhole formation under the main road, the light rail system, and neighboring properties. Furthermore, it led to the accumulation of a substantial water pool within the construction site, impeding further excavation efforts. Geotech contractors The Injection Experts AU were called in to solve the problem.

Powerful Polymers

The following materials were chosen for the project: AP Fill 720 was selected for full curtain injection behind the secant pile wall system to stabilize and seal the voids and leaks. Oakum was chosen to plug large voids and gushing leaks due to its ability to quickly stop high-flow water intrusion when soaked in resin. Spetec AG200 was chosen for injecting minor leaks because of its ability to penetrate and seal hairline cracks.

Painless Procedures

AP Fill 720 was pumped through an Alchatek PolyShark pump into 1.1m x 13mm injection rods. This was done to fill the voids left by escaping sand and water and to create a waterproof barrier on the back side of the secant piles. Oakum, soaked in resin, was packed into voids and large holes. This measure aimed to slow down the ingress of sand and water into the basement while excavation and injection processes were ongoing. Spetec AG200 was injected through 13mm packers to seal any fine hairline cracks and to provide touch-up sealing around the injection rods.

Rapid Results

The repair efforts were ultimately a success. Through the strategic use of polyurethane grouting methods, the voids and leaks in the secant pile wall system were effectively sealed. This meticulous process not only waterproofed the basement area but also mitigated the risk of sinkholes forming under the nearby road, light rail, and neighboring lots. As a result, the project was able to proceed safely without further excavation issues, marking a triumphant conclusion to a challenging endeavor.

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