Collection and protection for small islands

Two widely different floating structure projects that bring big benefits to small islands in Europe and South East Asia have recently been completed by SF Marina.

Gressholmen-Rambergøya, a short ride from the Norwegian capital Oslo, now has a novel floating dock with containment for rubbish that could otherwise blight the popular nature preserve. Hei Ling Chau – thanks to a new SF Marina floating concrete wave attenuator – provides Hong Kong with a new typhoon shelter basin.
Floating garbage dock
Disposing of waste on a small island that has no vehicle access posed a tricky problem for Kommune Bymiljøetaten, the municipal urban environmental agency in Oslo. The solution, developed with SF Marina, was to devise a waste collection point right at the dockside. A small floating concrete dock houses three Molok Deep Collection trash containers that are emptied from the water using a crane mounted on a garbage collection workboat.
The project uses an SF Marina 4m (13ft) wide x 15m (49ft) long SF1040 floating concrete pontoon. Highly adaptable to a wide range of applications, this type of pontoon can be modified to meet the needs of virtually any project. Three holes for the Molok containers were cast into the structure during manufacture at SF Marina’s Wallham facility in Sweden, shipped to Oslo and then floated to the island.
Used primarily as a dock section, the SF1040 is extremely stable due to its sheer mass and low centre of gravity. While the Gressholmen-Rambergøya floating garbage depot is located in a sheltered cove and anchored to the seabed with chains and anchors, SF Marina pontoons are engineered to withstand hurricane-force weather events.
Typically used on land, 60% of a 5m³ Molok container is normally underground—but, in the case of the SF Marina project, it is underwater. The cool surroundings keep odour-producing bacteria from forming and, as much of the container is hidden, the receptacle opening is low and thus accessible by children and those in wheelchairs. A 6m (20ft) walkway allows easy entrance to the dock from shore and accommodates the area’s mild tidal fluctuation.
Each container cover has a reusable inner sleeve that holds the refuse. The crane lifts the lid and contents, swings it over to the boat, and a worker pulls a rope that opens the bottom to spill the trash. Because of the containers’ large capacities, 80% fewer emptyings are required over standard-sized waste receptacles.
Typhoon shelter basin
Part of Hong Kong, Hei Ling Chau is a small island situated off the east coast of Lantau Island that’s home to an addiction treatment centre and two correctional institutions. Due to frequent tropical cyclones in the region, the Hong Kong Government determined the waters off Hei Ling Chau’s western shore would make an ideal typhoon shelter basin.
SF Marina installed a 700m (2,300ft) long floating concrete wave attenuator. Prior to this, the basin was surrounded by a two-section fixed-rock breakwater that only protected the area under normal storm conditions. The Hong Kong Government chose SF because it could manufacture the wave attenuator quickly in Asia and has a proven track record of installations successfully surviving severe storms.
The Hei Ling Chau project comprises 30 sections of 20m (66ft) long x 5m (16ft) wide 65-tonne SFBW500 pontoons and five sections of 20m (66ft) x 4m (13ft) 55-tonne SFBW400 pontoons. With a height of 1.8m (6ft), they share a 0.5m (1ft 7in) freeboard and 500kg/m² buoyancy rating. The pontoons and anchors were manufactured by SF Marina Korea and shipped to Hong Kong. They were unloaded, floated into position using a tug, and installed.