CASE STUDY
SeaShield 2020SP™ system protects 130m of sheet pile wall at Rottnest Island
Subsea & Splash Zone Coatings
Project Data
| Location | WA |
| Asset Owner | Rottnest Island |
| System | SeaShield 2020SP™ system |
| Date | 2024 |
Project Background:
In 2024, Denso Australia’s SeaShield 2020SP™ System was selected to provide long-term corrosion protection to the 130m length of sheet pile wall located in the main jetty of Wadjemup/ Rottnest Island.
The Main Jetty is Rottnest Island’s largest maritime service structure, with the barge ramp being used for daily cargo operations to and from the mainland located at the base of the jetty.
In addition, the jetty is the main arterial point of entry for island visitors and marks the place where they commence their Rottnest Island experience as they disembark from ferries. It is also the sole entry and exit point for ferry operators while the barge ramp is used for commercial deliveries.
The Problem and Solution:
The sheet pile wall on Rottnest island was constructed in stages beginning in the 1960s and has suffered severe corrosion in the splash zone over that time. The SeaShield 2020SP™ System was selected to prevent further corrosion and provide a life extension to the structure.
Offering a comprehensive, long-term corrosion protection solution would require us to accommodate for tie-back points as well as varying heights along the length of the wall, a challenge the 2020SP system takes in its stride.
The system was applied both above and below the water line and this allowed applicators to continue the works under tight timelines and unfavourable tides to get the project completed prior to the busy summer season.
Minimal Surface Preparation:
A 3D scan of the sheet pile configuration was completed at the beginning of June 2024. The project contractor, Advanteering Civil Engineers were then mobilised to tackle the surface preparation of the substrate.
The removal of all loose corrosion and marine growth was achieved using a hull scrubber and a 5000 PSI water jetter.
Since the SeaShield systems easily fill and protect deeply pitted steel, the surface preparation was far simpler than for other methods, and the effectiveness of SeaShield systems to halt future corrosion meant the need for repair plates to repair corroded sections was avoided.
Application Details:
Welded Bars
Welded bars are stitch welded to the pile face to allow for the attachment of the HDPE Wall Spines.
Primer (First Corrosion Protection Barrier)
SeaShield Primer was applied in order to fill all pitting and surface imperfections on the sheet pile wall.
Marine Piling Tape (Second Corrosion Protection Barrier)
A minimum of two layers of marine piling tape were applied to the internal face of the wall and three layers onto the front face.
Wall Attachment Spines
HDPE wall attachment spines are prepared by inserting nuts and stainless steel fasteners before being attached to the welded bars onto the sheet pile wall.
Foam Fillers
Foam in-fill blocks are used to provide a convex path for the jackets so that the hoop pressure generated during tensioning keeps the marine-grade petrolatum tape firmly pressed against the wall.
Outer Armouring
2mm thickness HDPE jackets are placed between two spines and tensioned. To accommodate for the varying heights of Rottnest Island’s wall, we used a combination of our standard length 1.53m jackets and a smaller 1.3m jacket size.
Comparison between sheet pile protection solutions:
View of completed SeaShield 2020SP™ system at Rottnest Island's main jetty.
Rottnest Island's main jetty from afar.
Close-up view of the completed SeaShield 2020SP™ system.
View of completed SeaShield 2020SP™ system at Rottnest Island's main jetty.
Rottnest Island's main jetty from afar.
