Keller, the world’s leader in geotechnical solutions, announces the completion of its first interlocking pipe pile system for Alamos Island Gold Mine in Dubreuilville, Ontario.

Interlocking pipe piles rig at work

When the Gold Mine encountered unexpected ground conditions at the proposed site for their tailings dam expansion, a 40m (131 ft) long cut-off wall was required.

Various solutions were considered but with several meters of thick sand and gravel till, cobbles, boulders underlaid by bedrock, and flowing water conditions, interlocking pipe piles were chosen as the preferred solution.

Other benefits of using interlocking pipe piles include rapid construction using a rotary percussive drilling process in a single pass and a watertight seal using mechanical interlocks. Like sheet piles, the interlocking pipe pile system creates a cut-off wall and can be used for excavation support. However, while sheet piles would refuse to drive through rock and boulders, a down-the-hole hammer is used to advance the interlocking pipe pile through these conditions.

Keller crews installed 68 interlocking pipe piles with lengths varying from 5m (16.4 ft) to 11m (36.08 ft) as required. Interlocking pipe piles were 610mm (2 ft) in diameter. Project Manager Anojan Siva states, “We were involved early on in the process to explain the pros and cons of several potential cut-off wall techniques.” He continues, “We were able to discuss and resolve anticipated constructability challenges, technical considerations, and address the time-sensitive requirements for this critical project."

Overall, Ledcor and Alamos Gold, the client, and owner respectively, were extremely pleased with the team’s professionalism and resourcefulness, and execution of the cut-off wall. During construction, Keller provided high caliber experienced personnel working six days a week for six weeks. “We were able to provide a high-quality solution using a pile guide/template to ensure pile location and verticality, and performed a continuous inspection and monitoring of all activities,” Anojan said. The project was completed on schedule and Keller has already planned future projects using interlocking pipe pile technology.

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