2020 review of maintenance dredging of Queensland ports
This review has been prepared by the Queensland Ports Association as part of reporting requirements under the Maintenance Dredging Strategy for Great Barrier Reef World Heritage Area Ports.
Queensland ports require routine maintenance dredging to remove sediments that have accumulated in channels, berths and swing basins due to siltation and sediment transport processes. Most ports cannot sustainably function without maintenance dredging. Maintenance dredging has occurred in Queensland since ports were first established.
Most maintenance dredging is carried out by the Trailing Suction Hopper Dredge Brisbane which undertakes an annual dredging program of Queensland ports over a period of 6–8 months. The dredge, based in Brisbane and operated by the Port of Brisbane Pty Ltd, was specifically designed and built for Queensland conditions with the vessel applying high standards of environmental management. The environmental management mechanisms are equivalent to the features installed in the latest Trailing Suction Hopper Dredge models used around the world and ensure environmental impact is minimised during the dredging works.
In accordance with the Queensland Maintenance Dredging Strategy for Great Barrier Reef World Heritage Area Ports, a high-level schedule of maintenance dredging activities for 2020 was prepared and provided to the Department of Transport and Main Roads. The schedule specifically considered opportunities to minimise both the extent and footprint of dredging activities.
During 2020, maintenance dredging was undertaken at the following ports:
This maintenance dredge program is now complete.
The sections below summarise the outcomes of the 2020 dredge program at each of the above ports in relation to timing, volume and outcomes of monitoring. The comprehensive assessment of disposal options for all maintenance dredge campaigns is undertaken as part of each ports Long Term Maintenance Dredging Management Plan.
It should be noted that in 2020, the marine pest species White Colonial Sea Squirt (Didemnum perlucidum) was detected at a number of ports throughout Queensland. Detections of this species were also recorded in 2021. The fecundity of this species limits potential eradication options however Queensland Ports Association will continue to work with Biosecurity Queensland for any further management measures that may be required.
The outcomes of this review will be considered and incorporated into the maintenance dredging schedule for 2021.
Port of Brisbane
Maintenance dredging
A total of 430,150m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 20 December 2019 to 6 March 2020 and 3 July 2020 to 5 September 2020. Dredging was undertaken in the Brisbane River.
Activities were fully compliant with all state approvals (Environmental Authority, Marine Park Permit and Allocation of Quarry Material) and no environmental incidents or complaints were reported.
Environmental assessments
Seagrass
The Port of Brisbane Seagrass Monitoring Program annual survey was undertaken by BMT in July and August 2020. Consistent with previous years, although only four of five seagrass species were recorded (Halodule univeris not recorded). Year to year variability in composition and extent of seagrass meadows has continued. Seagrass depth range has remained stable at Fisherman Islands since 2018. Overall, there has been a long-term trend of increasing seagrass meadow extent at Fisherman Islands which continues to represent a critical ecosystem component in western Moreton Bay.
Water
Triennial dredging turbidity monitoring was last undertaken in February 2020. The monitoring found that the dredging activity created larger plumes than the dredged material disposal. Plumes remained within both dredging areas and the dredged material placement area and there was no impacts on sensitive receptor sites.
Sediment
The annual Sediment Sampling and Analysis Plan was undertaken in August 2018. 43 samples across 4 zones plus reference and placement sites. All sediment determined to be suitable for unconfined ocean disposal.
Turtles and dugongs
No interaction with dredging.
Biosecurity
Brisbane underwent out-of-water refit in Cairns in November 2020. Inspection of the hull and associated areas detected no marine pests of concern. Fresh antifoul paint was applied.
In January 2020 the marine pest species White Colonial Sea Squirt (Didemnum perlucidum) was detected at the Port of Brisbane. Throughout 2020 multiple detections of this species along the Queensland coastline was confirmed by Biosecurity Queensland. The fecundity of this species limits potential eradication options however Port of Brisbane Pty Ltd continue to work with Biosecurity Queensland for any further management measures that may be required.
View Port of Brisbane monitoring reports.
Port of Bundaberg
Maintenance dredging
A total of 66,221m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 10 April 2020 to 17 April 2020. Dredging was undertaken at the berths, swing basins, inner and outer channels.
No permit non-compliances, environmental incidents or complaints were reported.
Environmental assessments
Seagrass
The Port of Bundaberg Long Term Maintenance Dredging Management Plan monitoring for seagrass, benthic and particle size analysis assessment at the disposal site is undertaken every five years with the last survey carried out in 2020. Initial communications with sampling specialist indicate good coverage of seagrass within and around the material placement area.
Water
A water quality monitoring program has been designed and implemented to ensure water quality does not deteriorate as a result of maintenance dredging and thus to protect sensitive receptors in the area. The whole suite of water quality physico-chemical parameters is collected in real-time by a multiparameter sonde. Turbidity data is used in conjunction with an adaptive management framework that prompts evaluation and management actions.
No water quality impact was detected from the activity.
Sediment
Sediment quality assessment following the National Assessment Guidelines for Dredging 2009 was last conducted in 2019 and found to be suitable for placement at sea.
Turtles and dugongs
Indirect impacts to these species are mitigated through the management of water quality during maintenance dredging activities.
Direct impacts are mitigated through controls documented in environmental management plans. These include fitting of turtle exclusion devices and includes visual observations with protocols on when to stop activities, wait, and re-commence activity, plus guidance on reporting.
No impacts to marine megafauna was identified from the activity.
Biosecurity
No marine pests identified during the activity.
View Port of Bundaberg monitoring reports.
Port of Cairns
Maintenance dredging
A total of 136,309m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 20 April 2020 to 1 May 2020. Dredging was undertaken at the Port of Cairns channel.
At portions of the inner port wharves (1–12), Navy Base and marinas the Willunga Grab Dredge dredged 43,071m3 throughout the year.
All works were compliant and consistent with approval conditions. The volume dredged was within annual permit limit. The annual return and annual fee for the Environmental Authority was submitted. No permit non-compliances, environmental incidents or complaints were reported.
Environmental assessments
Seagrass
Cairns Harbour and Trinity Inlet Long Term Seagrass Long Term Monitoring Program – annual survey completed by James Cook University, TropWater, during November (helicopter) and December (vessel) 2020. Light data collection and seed viability surveys continued.
Water
Water quality verification under the management plans not required during the period, and no campaign specific sampling conducted.
Sediment
Sediment Analysis Plan – implemented between February and March 2020 for the channel, inner port, marina, and Navy Base areas.
No detection of contaminants exceeding National Assessment Guidelines for Dredging 2009 limits, and material assessed as suitable for unconfined at sea placement under permit conditions.
Turtles and dugongs
No interactions or observations recorded during dredging or placement operations of either the Trailing Suction Hopper Dredge Brisbane or Willunga-tug and barge activity.
Biosecurity
Surveys of areas to be dredged as set out in the Sediment Analysis Plan, along with periodic checks of the monitoring devices within the inner port area were conducted, with no detections of actual or suspect material during 2020 period. Implementation of Biosecurity Queensland’s Seaports eDNA Surveillance (Q-SEAS) program enacted, with detection of one non-priority marine pest (Black Scar Oyster) occurring.
Port of Gladstone
Maintenance dredging
A total of 255,986m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 8 September 2020 to 12 October 2020. Dredging was undertaken at the berths, swing basins, inner and outer channels.
The Saibai Cutter Suction Dredge dredged 186,055m3 from the marina from 18 May 2020 to 7 November 2020.
No permit non-compliances, environmental incidents or complaints were reported.
Environmental assessments
Seagrass
Light is monitored in real time at a seagrass meadow within the potential zone of influence before, during and after dredging. The light monitoring, in conjunction with an adaptive framework flowchart, prompts evaluation and management actions to protect seagrass.
This is supported by an annual seagrass monitoring program that maps and monitors the health of meadows.
No impact was detected from the 2020 campaign.
Water
Trailing Suction Hopper Dredge: Real time turbidity monitoring is undertaken inside and outside the potential zone of influence as determined by modelling of maintenance dredging plumes and used in conjunction with an adaptive management framework that prompts evaluation and management actions.
Cutter Suction Dredge: Real time turbidity monitoring is undertaken on decant waters along with grab samples to verify Total Suspended Solids and measure metal/Tributyltin concentrations. These measurements are used in conjunction with an adaptive management flowchart that prompts evaluation and management actions.
No impact was detected from the 2020 campaigns.
Sediment
In line with the long-term monitoring schedule in the Port of Gladstone Long Term Maintenance Dredging Management Plan, sediment quality in the main channels is assessed every five years. The sediment quality was assessed in 2017 using the National Assessment Guidelines for Dredging 2009 and found to be suitable for placement at sea.
Turtles and dugongs
Indirect impacts to these species are mitigated through the management of water quality and seagrass meadows during maintenance dredging activities.
Direct impacts are mitigated through controls documented in environmental management plans. These include fitting of turtle exclusion devices (where possible) and including visual observation with protocols on when to stop activities, wait, increase visual observations and commence or re-commence activity and guidance on reporting.
No impacts to marine megafauna were identified from the activity.
Biosecurity
The Port of Gladstone Long Term Maintenance Dredging Management Plan has a five-yearly Marine Pest Survey schedule, last conducted by the Department of Agriculture and Fisheries in 2019–2020. The survey confirmed no detections of invasive marine pests. Gladstone Ports Corporation is continuing their involvement in an annual integrated ports program with the Department of Agriculture and Fisheries in 2021.
View Port of Gladstone monitoring reports.
Port of Mackay
Maintenance dredging
A total of 123,870m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 13 December 2020 to 24 December 2020. Dredging was undertaken at the berths, swing basins and siltation trench.
Activities were compliant with all state and federal approvals and no environmental incidents or complaints were reported.
Environmental assessments
Seagrass
Annual seagrass monitoring was conducted in the Port of Mackay and Hay Point in October 2020. Monitoring found seagrass in the deep-water survey block off Mackay and around Keswick Island were in average to good condition, with a substantial reduction in area for the deep-water seagrasses off Hay Point compared to the very high levels observed last year (that is, back to levels more typically observed in previous years). Coastal seagrass around Dudgeon Point also declined compared to 2019 levels. There was an abundance of turtles identified at the Keswick Island survey locations.
Long-term trends for the Mackay Hay Point region indicate regular annual occurrence of the colonising species Halophila decipiens between July and December and the occasional occurrence of Halophila spinulosa within the greater port limits. For the remainder of the year their populations remain dormant in the form of a seed bank. Annual surveys in the port region over the last 15 years as part of the North Queensland Bulk Ports/James Cook University seagrass monitoring partnership have found significant inter‐annual variability in both the spatial extent and above‐ground density of seagrass in the area.
Water
North Queensland Bulk Ports completed ambient marine water quality monitoring prior to, during and post the maintenance dredging program. Satellite derived turbidity data was also used to monitor any potential dredge plume. No management actions were required and no impacts (dredge related plumes) on sensitive receiving environments were observed.
Sediment
A Sediment Characterisation Study was completed in December 2018 as per the National Assessment Guidelines for Dredging 2009. The sampling confirmed compliance of maintenance dredge material to the guidelines and suitability for ocean disposal at the current approved Dredge Material Placement Area.
Turtles and dugongs
No interactions or observations were recorded during dredging or placement operations. Mitigation measures such as turtle deflectors and spotter records were assessed as compliant during the Internal Environmental Audit completed during the works.
Biosecurity
No marine pests identified during activity in December 2020.
In March 2020 the marine pest species White Colonial Sea Squirt (Didemnum perlucidum) was detected within Mackay Port. Throughout 2020 multiple detections of this species along the Queensland coastline was confirmed by Biosecurity Queensland. The fecundity of this species limits potential eradication options however North Queensland Bulk Ports continue to work with Biosecurity Queensland for any further management measures that may be required.
Specific management measures were implemented during dredging activity at Mackay to minimise the potential spread of this species (Dredge Environmental Management Plan).
Port of Townsville
Maintenance dredging
A total of 499,086m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 1 June 2020 to 29 June 2020. Dredging was undertaken at the Platypus and Sea channels, inner and outer harbours.
At berths 4 and 8, and Ross Creek, 1930m3 was intermittently dredged by a Grab Dredge between 16 March 2020 to 17 June 2020. No permit non-compliances, environmental incidents or complaints were reported.
Environmental assessments
Seagrass
Seagrass monitoring within Cleveland Bay was undertaken in September and October 2020.
View the 2019 Cleveland Bay monitoring report.
Water
Marine water quality monitoring was undertaken 4 times during 2020 at locations within or adjacent to the receiving environment (Ross River, Ross Creek, Cleveland Bay). Samples were analysed for suspended solids, nutrients and metals. Results were similar to previous years. Results have contributed to the Dry Tropics Partnership for Healthy Waters Annual Report Card.
Turbidity and light data was collected in 2020 at several underwater locations in Cleveland Bay. Two real time water quality buoys in Cleveland Bay also measured turbidity, temperature and electrical conductivity throughout the year, including during maintenance dredging and placement activities. Turbidity levels were within the ambient levels throughout maintenance dredging and placement activities. Data from these buoys is available on a water quality dashboard on the Port’s website.
Sediment
In line with the National Assessment Guidelines for Dredging 2009, sediment quality is assessed every 5 years. The sediment quality was assessed in 2017 and 2018 and all material, except that in Berths 2, 3, 7 and 8, has been found to be suitable for placement at sea. In 2020 sediment quality in Ross Creek was assessed against the guidelines and was determined not suitable for placement at sea.
Turtles and dugongs
Visual observations were undertaken during dredging. No interactions with dredges.
Biosecurity
Port of Townsville is partnering with Biosecurity Queensland and other Queensland Port Authorities on the Queensland Seaports eDNA Surveillance (Q-SEAS) marine pest pilot program. The White Colonial Sea Squirt was detected in the Townsville Marine Precinct as part of this program. All users of precinct were informed and measures and monitoring put in place to minimise potential spread of this marine pest.
Throughout 2020, multiple detections of this species along other locations on the Queensland coastline was confirmed by Biosecurity Queensland The fecundity of this species limits potential eradication options however Port of Townsville Limited continue to work with Biosecurity Queensland for any further management measures that may be required.
Port of Weipa
Maintenance dredging
A total of 355,953m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 4 May 2020 to 28 May 2020. Dredging was undertaken at the Port of Weipa South Channel, inner harbour and berths.
Activities compliant with state and federal approvals and no environmental incidents or complaints were reported.
Environmental assessments
Seagrass
Annual seagrass monitoring was conducted in the Port of Weipa between the 29 August and 3 September 2020. Monitoring in 2020 found seagrasses in the Port of Weipa were in overall good condition.
All monitoring meadows were in good or very good condition for all three indicators measured; biomass, area and species composition with the exception of species composition in one area which decreased to satisfactory. Total area of seagrass meadows in the region closest to the port (Intensive Monitoring Area) was above the long-term average for the fifth consecutive year. Seagrass cover across the whole port (including Pine River Bay, Embley and Mission Rivers) was higher than any other survey since monitoring began in 2000. Dugong feeding trails were observed throughout seagrass meadows in the port.
Water
North Queensland Bulk Ports completed ambient marine water quality monitoring prior to and during the maintenance dredging program. Data from the water quality monitoring as well as satellite-derived turbidity data was analysed.
The data showed that during the 2020 maintenance dredging program, the turbidity was generally controlled by the natural conditions (tidal currents and wind/wave conditions), with higher turbidity occurring during periods with larger waves. The Port of Weipa 2020 maintenance dredging program did not influence the regional turbidity of the area.
Sediment
A Sediment Characterisation Study was completed in March 2018 as per the 5-yearly requirement under the National Assessment Guidelines for Dredging 2009. The sampling confirmed compliance of maintenance dredge material to the guidelines and continued suitability for ocean disposal at the approved Albatross Bay Dredged Material Placement Area.
Turtles and dugongs
No interactions or observations were recorded during dredging or placement operations. Mitigation measures such as turtle deflectors and spotter records were assessed as compliant during the Internal Environmental Audit completed during the works.
Biosecurity
No marine pests identified during activity.
In early 2020, the marine pest species White Colonial Sea Squirt (Didemnum perlucidum) was detected within adjacent Port facilities of Amrun. Whilst this species has not been confirmed within the Port of Weipa, throughout 2020, multiple detections of this species along other locations on the Queensland coastline was confirmed by Biosecurity Queensland. The fecundity of this species limits potential eradication options however North Queensland Bulk Ports continue to work with Biosecurity Queensland for any further management measures that may be required.
Specific management measures were implemented during dredging activity at Weipa to minimise the incursion of marine pest species (Dredge Environmental Management Plan).
- Last updated 14 May 2024