Infrastructure
Water
Belmont Ocean Outfall, New South Wales
The project team, in joint venture, was contracted to fabricate and install a 1.8km long ocean outfall to replace the existing tidal discharge from the Belmont Treatment Works. The location of the pipeline, on an exposed section of the coastline, necessitated the use of special construction methods to achieve the required burial depth and counteract the effects of littoral drift.
FEATURES:
Sintakoted pipes were delivered to site in 9m lengths where they were concrete weight coated and assembled into 144m strings, ready for launching.
The installation of the 1.8km long pipeline, with an internal diameter of 1.4m beneath the seabed, called for specialist construction methods. Working from a 500m long temporary jetty, a 3m diameter "tunnel"was constructed in the sea bed to direct the pipeline through the surf zone at depths of up to 9m beneath the seabed. Beyond the jetty, an open trench was prepared, using a purpose-built dredge, capable of operating in up to 25m of water.
After being pulled through surf zone tunnel, the pipeline was installed using the bottom tow method.
Sudden weather deterioration necessitated the pipeline being installed in two lengths with a subsea joint constructed in 12m water depth.
BENEFITS:
The project team drew on its extensive experience in ocean outfall construction to ensure the successful completion of the project. They were able to employ and train local personnel, and achieved a good safety record on site, completing the contract on time and within budget.
CLIENT: Department of Public Works, Newcastle
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