Port Germein Jetty Storm Damage and Repair Design

The challenge

Port Germein Jetty is the longest jetty in South Australia and one of the main reasons visitors and anglers come to the town. Built in the 1880s and open to the public without restriction, it had been quietly deteriorating for decades: corrosion had taken section from steel components, timber piles, corbels and girders had lost material through rot and splitting, and bolted connections through the structure had loosened or corroded. Two severe storms in May and June 2025 then pushed water levels above the deck and damaged members along the jetty. The District Council of Mount Remarkable needed an accurate picture of what it owned, a clear separation of storm damage from long term deterioration, and repair details it could actually put out to construction so the jetty could stay open and safe.

Our approach

The governing question was what this jetty actually has to resist. Port Germein sits roughly 300 kilometres inside Spencer Gulf, so Southern Ocean swell never reaches it and the design waves are generated locally by wind blowing up the gulf, which meant an open coast load case would have been the wrong starting point. Site specific wave modelling was used to derive the design wave heights, water levels and the wave in deck loads that arise once water reaches the underside of the deck, and because the largest wave and the highest storm tide rarely arrive together, the two were assessed jointly to find the combination that governs. That combination lines up with the uplift damage recorded after the storms of May and June 2025, which gave confidence the load case was right. The structure itself was assessed bent by bent and component by component, above and below the water line, so the repairs are set against measured condition rather than assumed age. Repair details follow Department for Infrastructure and Transport master specifications, checked against the site loads and against what the crews who maintain the jetty can practically build.

The outcome

The work gives the District Council of Mount Remarkable an evidence based picture of the jetty and a repair package ready for construction. Condition is rated across the full length of the structure, storm damage is separated from long term deterioration, and repair priorities are set so the most exposed bents are dealt with first. The design drawings and specifications cover replacement of deteriorated timber and steel components and the bolted connections that hold the structure together, detailed to standards already proven on jetties around South Australia. Repairs are designed for the wave and storm tide conditions expected at Port Germein over the design life, with allowance for sea level rise, so the structure is restored against the conditions that damaged it rather than the conditions of a century ago. For the town, that protects a heritage structure that remains its strongest draw for tourism and fishing, and keeps it open to the public.