Portland Experience

The Port of Portland Experience

The Sand Shifter system was first commercially proven in the Port of Portland Sands Bypassing System where it was adopted the dredge the harbour entrance as well as provide a fixed sands bypass system for the ongoing transfer of littoral drift sand on a long term basis.

The system recovers sand from two traps approximately 120 metres apart and 60 metres offshore on the eastern side of the Main Breakwater. The sand is pumped under the entrance and discharges 3 km. North of the harbour at Anderson Point. The system is normally operated weekly to transport sand which has accumulated in either trap. Two fixed Sand Shifter units are installed offshore the main breakwater and sand is fed to the fixed units by wave action.

The fixed pumping equipment is electrically driven and is installed in two containerised pump stations on the main breakwater.

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Fully Automatic System

The system is fully automated using a programmable logic controller (PLC) and personal computer for remote, unattended operation. Sand production rates are continuously metered via the uses of a flow meter and desensitometer.

The harbour crossing pipeline is fully welded, heavy wall steel.

It is entrenched under the main shipping channel. Cathodic protection is by sacrificial anodes at each end of the pipe. The on-shore pipeline is medium density polyethylene and joined by victaulic couplings.

Production capacity is 70 - 150 cu.m of in-situ sand per hour. SlurrySystems initially dredged 230,00 cu.m of sand accumulation using a mobile Sand Shifter/Jet Pump combination while installing the permanent system.

The technology used for the Portland system is suited to service multiple entrances as a road transportable system.

To date, all maintenance on th Portland units has been carried out by divers, without the need for expensive supporting equipment or recovery of the Sand Shifter units.