Dredging: a valuable process

Waterways underpin our way of life and our city’s prosperity. Our waterways have a significant economic, social and environmental value to the Gold Coast community. Our role managing the waterways isn’t just about what’s on top of the waterways, it’s also about what’s happening below!

Looking after our waterways means making sure they are clear, accessible and safe for everyone to use.  Like mowing the lawn or weeding the garden, dredging is vital maintenance. Keeping these channels safe to navigate is a vitally important part of Gold Coast Waterways Authority’s (GCWA) ongoing role, as is striking the balance between safe use, available funding and protection of the environment. Our Projects has more information on our specific dredging projects.

What is dredging?

Dredging involves removing sediment (sand, silt and mud) from the bottom of a channel of water to create the required depth for the safe navigation of vessels. Using machinery to move sediment to a different location, dredging creates a deeper or wider waterway.

Dredging is part of our commitment to maintaining open and safe access for all waterways users. Dredging of Gold Coast waterways is undertaken by both the GCWA and City of Gold Coast.

Check out how we’re maintaining navigational access in Gold Coast waterways:

 

Maintenance

Our waterways are a complex system of naturally shallow areas and channels that are affected by tides, weather conditions and build up of sediment. Sand movement is part of a dynamic coastal system and can cause channels to become too narrow or shallow to be safe to access and easy to navigate.

Dredging allows us to manage this for the safety and benefit of all waterways users.

Benefits

Dredging has many positive effects and benefits for the natural environment and our community. These include:

  • safe and open access for vessels
  • proactive maintenance of channels at risk of becoming too shallow
  • reuse of sand to nourish neighbouring beaches and replenish eroded areas
  • reuse of sand to upgrade foreshores and amenities including landscaping
  • flood prevention / mitigation by increasing channel capacity
  • reduced risk to properties and amenities through flooding
  • improved water quality
  • improving the health of aquatic ecosystems.

What to expect

You’ll see our contractors out and about on the waterways and foreshore with large machines to undertake this maintenance.

The most common machine you’ll see is the cutter suction dredge. It is a stationary vessel with a cutter head that moves across the bottom of the channel, sucking up sediment and delivering it through a floating pipeline to the adjacent foreshore. Using this machine, we collect sediment from the bottom of the channel and move and shape reused sand. In many locations, the dredged sediment is clean sand which can be reused to replenish and restore beaches, shorelines and habitats.

Sometimes the dredged sand contains fine sediment particles from the seabed floor which give it a dark appearance for short time. This sand is not ‘dirty’ and the dark appearance will change as the particles settle out of the sand and become bleached by the sun . Within two months of the dredging, the sand will change back to its original natural ‘white’ state.

What about the impacts on the environment?

Dredging is highly regulated and subject to State and Commonwealth legislation. We undertake extensive environmental impact assessments and meet all required approvals.Dredging projects on the Gold Coast are well managed and we closely monitor the effects of this work on our beautiful natural environment. More than 90% of dredged material is unpolluted, natural and undisturbed sand which can be reused on beaches.

Our Dredging – Navigation Channels, Anchorages and Destinations Plan

The purpose of our Dredging – Navigation Channels, Anchorages and Destinations Plan is to provide guidance to employees, the Chief Executive Officer of GCWA and the GCWA Board, when considering dredging of navigation channels and anchorages. The plan is also to inform waterways users of the considerations made with respect to dredging of navigation channels and anchorages.

Report for Gold Coast Waterways Access Needs Study – Final Report

The Report for Gold Coast Waterways Access Needs Study – Final Report documents the marine industry’s perceived need in relation to navigational channel profiles in Gold Coast waterways. It also provides estimates of the investment required to establish and maintain
the identified profiles, and assesses the merits of that investment. This document was co-funded by the Department of Infrastructure and Planning and was developed in part to inform their Southern Moreton Bay Marine Infrastructure Master Plan.

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Last updated: 20 November 2017