James W. Fowler Co. selected IQIP’s S-90 Hydrohammer to help install a 12ft-wide (3.6m) tunnel in Portland, Oregon USA. The project was overseen by the general contractor, Hoffman Construction Company.
The Hydrohammer – with a P-250 power pack and 24” (610mm) guide sleeve – is highly suitable on such a project where space is tight. Construction took place in a cofferdam, which was first excavated and reinforced by the general contractor. James W. Fowler Co. chose the Hydrohammer due to its compact footprint – ideal for confined spaces – and efficient transfer of energy from the hammer through an adaptor cone to the pipe. Due to the small sleeve, less energy was needed to move the anvil, with most of the energy instead being transferred directly through the cone into the tunnel section.
Cables were hooked alongside the hammer and to the cofferdam walls adjacent to the tunnel. As the piping sections were rammed, the hammer was tensioned and retained against the pipe to maintain constant piling pressure. The process was repeated for each new 10ft (3m) section. As the project was being completed underneath an existing road and metro track, James W. Fowler Co. opted to drive the tunnel to remove the risk of cave-ins. In addition, the Hydrohammer further condensed and compacted the surrounding soil after each impact. It has a maximum energy blow of 66,380ft-lb (90kNm) despite being only 26ft (8m) in length.