Heerema has received Statements of Feasibility from DNV GL for two of its “silent foundations” concepts, on which the company has been working together with the University of Dundee.
The concepts include helical or screw piles and so-called push-in piles, which could be installed without loud hammering that can be harmful to marine life and requires noise mitigation systems that produce a considerable CO2 footprint.
The helical pile foundation suits foundations that require shallow penetration in the seabed. The pile has a helical blade at its tip rotated during installation to allow the pile to penetrate the soil. This concept includes a moment arm that will connect to one of Heerema’s vessels to provide the required reaction force. Also, by reversing the process, this pile can be used for removing foundations allowing low-cost decommissioning and full recycling or re-use of piles, Heerema said.
The push-in pile design replaces a traditional single open tubular pile with a cluster of four smaller diameter open tubular piles. This design requires no pile-driving or hammering. Instead, after some strokes, each of the piles is pushed into the soil with two or three providing the uplift resistance required to push in the fourth. The concept uses a similar principle to onshore installations of sheet pile walls.
According to Heerema, the Statements of Feasibility for the two concepts are the first formal step towards qualifying these technologies for actual use in offshore structures.
“Despite the challenges in 2020, this development could continue with the University of Dundee’s support, who executed an extensive testing and modeling program”, Heerema said.