Maintenance dredging is being conducted at the Werribee River entrance as part of Parks Victoria’s program to ensure safe boating access at key entrances within Port Phillip and Western Port.
Why does Parks Victoria dredge the Werribee River?
As the local port and waterway manager for Port Phillip and Western Port, Parks Victoria is responsible for providing safe access to local port facilities. Over time sand naturally fills in boating access channels like the Werribee River entrance. Dredging designated channels is undertaken to maintain safe access to local port facilities like boat ramps, piers/jetties and harbours. Dredging has been occurring at the entrance for more than 20 years.
How often does dredging occur?
The decision to undertake to dredge is determined by the design depth of the area and minimum depth triggers. Parks Victoria regularly monitors water depths at Werribee River to determine when dredging is required. Dredging may occur any time of the year to ensure safe access for vessels in response to sedimentation cycles.
Where is the dredged material deposited?
The dredged sand is distributed in predetermined areas along the adjoining beach north of the river entrance or where it can benefit the beach profile. The natural direction of coastal sand movement is considered when establishing a delivery site for the dredged material. The sand will renourish the beach and replace what has been eroded.
Is the dredged material contaminated?
No. The dredged material is local sand that has washed into the entrance from the adjoining beaches as part of the local coastal processes. Parks Victoria completes testing at all of its sites requiring maintenance dredging and is committed to following the testing and environmental requirements outlined in the EPA Best Practice Guidelines for Dredging and other relevant regulatory standards. The quality of water will not be affected during dredging, but it may appear turbid (cloudy) until the sand settles. This is similar to strong wave action stirring up sand and sediments during storms.
Why is the sand deposited on the beach sometimes a dark colour and smell?
The sand is deposited onto a beach with a lot of water which helps with its transport. Wet sand is darker than dry sand, regardless of its natural colour. Also, sand usually contains decaying aquatic plant material, such as seaweed, which sometimes gives the dredged sand a grey appearance and a mild odour. These characteristics quickly change once it has been exposed to air, sunlight and tidal processes. Usually, within a week the sand is the same colour as the rest of the beach and the smell is gone.
What are the pipes for?
The pipes are used to transfer a slurry of sand and water from the dredge to the disposal site. As the sand and water flow out onto the site, the sand quickly settles and slowly accumulates as it builds up the beach. Additional pipes are gradually attached in order to progress along the beach or deliver the sand to a specific location.
Can I still use the beach?
Yes, unless otherwise marked onsite. Sections of the beach will be closed to the public during the dredging works for safety reasons. Once the dredging pipeline is in place, the beach will be reopened to the public, excluding an area at the disposal site. The disposal site is where the water and sand come out of the end of the pipe and will gradually move along the beach until dredging is complete. All temporary beach closures will be clearly marked. For safety reasons, visitors should keep away from the outfall pipe and any machinery operating in the area.
Can I still use the jetty?
Yes, unless otherwise marked onsite. Access to the jetty may be temporarily restricted to ensure the safe operation of the dredging equipment when working under and near the jetty. The boat ramps will also remain open.
Can I still use my boat in the river during the dredging?
Yes, the river entrance will remain open during the dredging. Mariners must always proceed with caution around a dredge and be aware of floating or submerged pipelines. When encountering a dredge, vessel operators should always maintain a safe speed and pass on the non-obstruction side of the dredge vessel. The safe side of passage is indicated by a double black diamond day shape on the vessel. A double black ball day shape indicates the obstruction side to avoid. A third, black ball – black diamond – black ball day shape indicates the vessel is restricted in its maneuverability.
How long will the dredging take?
The entire process is expected to take up to six weeks, depending on the weather. Further information Further queries, please contact the Parks Victoria information centre on 13 1963, or to receive email notifications about this and future maintenance dredging works at Werribee River entrance, email the Parks Victoria maintenance dredging team at dredging@parks.vic.gov.au
