Trailing Suction Hopper Dredge, Sand Suction Dredge, Environmental Monitoring, Sand Dredging, Tide Information, Dredging Pump Sand, Monitoring, Webcams, Gippsland

Trailing Suction Hopper Dredge

Dredging of the bar, parts of the entrance channel and a very limited number of locations in the inner channels is currently carried out using the Side Cast Dredge April Hamer.

A side cast dredge sucks the sand from the sea floor and pumps the sand through a discharge pipe on the vessel placing it a distance of approximately 30 metres from the dredge. This method of dredging is quite efficient and has maintained a channel across the bar for many years, however by virtue of the disposal only being 30 metres away sand soon returns to the where the channels have been dredged.

A primary aim of the Sand Management Program is to find an alternative method of maintaining the channels both efficiently and sustainably well into the future and this will include the trialling of Trailer Suction Hopper Dredge (TSHD).

The TSHD pumps sand from the sea floor and deposits it into a hopper within the dredge. The sand is then transported within the hopper to a nominated Dredged Material Ground (DMG) where the sand is deposited. The DMGs will be located offshore approximately 1500metres either side of the entrance just behind the surf zone.

By using the TSHD sand is removed from the bar, entrance channel and inner channels to a distance where it will not immediately re-enter the channels.

Environmental studies and monitoring ensure there are no adverse environmental consequences.

Since the commencement of the trials with the TSHD 'Pelican' on 1 March 2008 and up to the end of June 2008 the Pelican removed approximately 556,000 m3 of sand from the Bar, Entrance Channel and Narrows.

During the TSHD trial, observations of the beach in the locale of the Lakes Entrance Surf Club were monitored. The eastern DMG was directly offshore from the surf club.

It was observed that although the beach is highly dynamic, no changes to the beach were observed that have not occurred before.

Regular Hydrographic Surveys of the Bar and Entrance Channel indicate that removing the sand from this area using a Trailing Suction Hopper Dredge is the way forward. Local mariners have indicated the Bar and Entrance Channel has not been in this condition for generations.