2019 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 2019 were 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 2019, maintenance dredging was undertaken at the following ports:
This maintenance dredge program is now complete.
The sections below summarise the outcomes of the 2019 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.
The outcomes of this review will be considered and incorporated into the maintenance dredging schedule for 2020.
Amrun
Maintenance dredging
A total of 40,826m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 15 June 2019 to 29 June 2019. Dredging was undertaken at the Amrun export facility.
Activities were compliant with state and federal approvals and no environmental incidents or complaints were reported.
Environmental assessments
Seagrass
A small area of seagrass was recorded adjacent to the Boyd Bay beach (north of Boyd Point) with no seagrass found within the Boyd Point to Pera Head area with physical conditions, sediment and prevailing bathymetry unlikely to support seagrass in close proximity to the Port. Based on this and the information presented on water quality, impacts to seagrass are expected to be nil to low.
Water
Boat based turbidity monitoring was completed daily using a hand-held water quality probe that recorded turbidity at five inshore water quality monitoring locations with five readings collected approximately one metre from the seabed. Based on the data collected plume water quality impacts associated with dredging are assessed as nil to low.
All reports associated with dredging for 2019 will be published on the Amrun project website by 12 August 2020 in accordance with approval conditions.
Sediment
The Sediment Characterisation Study was completed in September 2017 and confirmed compliance of maintenance dredge material to the National Assessment Guidelines for Dredging 2009 and suitability for ocean disposal at the current approved material relocation area.
Turtles and dugongs
No interaction or observations were recorded during dredging or placement operations.
Biosecurity
No marine pests identified during the activity.
Port of Brisbane
Maintenance dredging
A total of 443,625m3 was dredged by the Trailing Suction Hopper Dredge Brisbane and the Grab Dredger Ken Harvey from 17 December 2018 to 21 March 2019 and 18 August 2019 to 26 August 2019. Dredging was undertaken in the Brisbane River North West Channel.
Activities were fully compliant with all state approvals (Environmental Authority, Marine Park Permit and Allocation of Quarry Material). No permit non-compliances or environmental complaints were reported regarding maintenance dredging operations or activities.
A green turtle was captured by the dredge at 0430 hours on 10 February 2019 whilst dredging in the Outer Bar Cutting. At the time of capture, all turtle exclusion devices were fitted and all procedures for minimising risk of turtle capture were being followed. The incident was reported to the state environment department and the Royal Society for the Prevention of Cruelty to Animals (RSPCA).
Environmental assessments
Seagrass
The Port of Brisbane Seagrass Monitoring Program annual survey was undertaken by BMT in July and August 2018. Consistent with previous years, five seagrass species were 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 last undertaken in 2017 (next due in 2020). Reclamation and dredge material placement area water quality monitoring buoys collecting real-time water quality data for dredge management. Reclamation sediment and water quality monitoring undertaken post dredging.
Sediment
The Annual Sediment Sampling and Analysis Plan was undertaken in August 2018. All sediment determined to be suitable for unconfined ocean disposal.
Turtles and dugongs
One green turtle capture during dredging in the Outer Bar Cutting. At the time of capture, all turtle exclusion devices were fitted and all procedures for minimising risk of turtle capture were being followed. The incident was reported to the state environment department and the RSPCA.
Biosecurity
Brisbane underwent out-of-water refit in Singapore in September 2018. Relevant inspections and risk assessments and controls implemented. All regulatory approvals obtained for re-entry into Australian waters.
Port of Brisbane Pty Ltd is also partnering with Biosecurity Queensland and other Queensland port authorities in an early warning pilot study.
View Port of Brisbane monitoring reports.
Port of Bundaberg
Maintenance dredging
A total of 66,200m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 22 March 2019 to 29 March 2019. Dredging was undertaken at the berths, swing basins, inner and outer channels.
Two reportable environmental incidents occurred during maintenance dredging. Notifications were made to the state and federal environment departments under the notification and reporting conditions of the environmental authority. The investigation identified that Gladstone Ports Corporation and Port of Brisbane Pty Ltd were dredging in accordance with approval requirements and environmental management plans. No environmental complaints were received.
Environmental assessments
Seagrass
The Long-Term Maintenance Dredging Management Plan monitoring schedule for seagrass, benthic and particle size analysis assessment at the disposal site is scheduled for monitoring every five years with the last survey undertaken in 2015.
Water
A water quality monitoring program has been designed and implemented to maintain water quality and protect sensitive receptors in the area. This includes real time turbidity monitoring.
No water quality impact was detected from the activity.
Sediment
Sediment quality assessment against the National Assessment Guidelines for Dredging 2009 was last conducted in 2014 and found to be suitable for placement at sea. In 2019, sediment quality was retested in Port of Bundaberg and Gladstone Ports Corporation is awaiting the results of this sampling program to inform future maintenance dredging programs.
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 and includes visual observation with protocols on when to stop activities, wait, and re-commence activity, plus guidance on reporting.
Two turtle strikes occurred in the Sea Reach section of the channel on 25 March 2019 and 29 March 2019 respectively, involving a Loggerhead Turtle and a Juvenile Green Turtle.
No impacts to other marine megafauna were 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 259,539m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 4 May 2019 to 22 May 2019. 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 60,420m3 throughout the year.
All works were compliant and consistent with approval conditions. The volume dredged was within the annual permit limit. The annual fee for the Environmental Authority was submitted during September, and annual return is to be submitted by 1 March 2020. No permit non-compliances, environmental incidents or complaints were reported.
Environmental assessments
Seagrass
The Cairns Harbour and Trinity Inlet Long Term Seagrass Long Term Monitoring Program annual survey was completed by James Cook University, TropWater, during November (helicopter) and December (vessel) 2019. Quarterly light data collection and seed viability surveys continued. Additional survey activity conducted to support the Cairns Shipping Development Project. End 2019 survey confirmed seagrass remains in sound and robust condition. The annual report is due early 2020.
Water
Water quality verification under the environmental management plans not required during the period, and program for Trinity Inlet inner port areas continued periodically, with outcomes consistent with long-term trends. Water quality instruments for the Cairns Shipping capital dredging Dredge Management Plan installed early and captured the maintenance-dredging period, with nil significant observations noted in respect of water quality.
Sediment
Sediment Analysis Plan implemented in February–March for the channel, inner port, marina, and Navy Base areas.
No detection of contaminants exceeding National Assessment Guideline for Dredging 2009 limits, and material again 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 2019 period.
Ports North is partnered with Biosecurity Queensland and other Queensland port authorities in an early warning pilot study—with first deployment of samplers and plankton assessment in October 2019 confirming nil detection of priority pest species. No biosecurity matters noted in respect of dredge vessels.
Port of Gladstone
Maintenance dredging
A total of 231,855m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 14 November 2019 to 18 December 2019. 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
A light monitor is deployed at the seagrass meadow within the potential zone of influence before, during and after dredging. Light thresholds have been established for seagrass at the Port of Gladstone and are applied to maintain growing season light requirements in conjunction with an adaptive management flowchart that prompts evaluation and management actions to protect seagrass. This is supported by ongoing ambient seagrass monitoring programs that map and monitor the health of meadows.
No impact was detected from the 2019 campaign.
Water
Real time turbidity monitoring is undertaken inside and outside the zone of influence as determined by hydrodynamic modelling of maintenance dredging plumes and used in conjunction with an adaptive management flowchart that prompts evaluation and management actions.
Impact detection water quality sites are sampled before, during and after dredging. This includes sampling for metals and Tributyltin at near and far field monitoring sites. This is supported by ambient real time water quality monitoring by Gladstone Ports Corporation at sites within the Port of Gladstone and support for the Port Curtis Integrated Monitoring Program and Gladstone Healthy Harbour Partnership.
No impact was detected from the 2019 campaign.
Sediment
In line with the monitoring schedule in the 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.
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 interactions or incidents.
Biosecurity
The Port of Gladstone Long Term Maintenance Dredging Management Plan has a five yearly Marine Pest Survey schedule, last conducted in 2015. None of the species recorded in the 2015 Biosecurity Survey of the Port of Gladstone are included in the Australian Emergency Marine Pest Plan Trigger List. Additionally, none of the species are listed as “high risk” species in either the Introduced Marine Pest or Declared Pest lists on National System for the Prevention and Management of Marine Pest Incursions.
No marine pests identified during activity. The Gladstone Ports Corporation is also partnering with Biosecurity Queensland and other Queensland port authorities in an early warning pilot study, which will meet the 2020 survey requirement.
View Port of Gladstone monitoring reports.
Port of Hay Point
Maintenance dredging
A total of 353,740m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 31 March 2019 to 2 May 2019. Dredging was undertaken at the Port of Hay Point berth pockets, apron and departure path.
Activities were compliant with state and federal approvals and no environmental incidents or complaints were reported.
Environmental assessments
Seagrass
Annual seagrass habitat surveys around the ports of Hay Point and Mackay were completed between the 1 and 9 October 2019. Seagrass was found at all the monitored areas (Hay Point and Mackay offshore waters, Dudgeon Point to Hay Point coastal meadows and Keswick and St Bees Islands). The seagrass was similar in distribution and abundance to the previous year, perhaps with a slight increase. Typically, Halodule uninervis and Halophila ovalis dominated the coastal sites while Halophila decipiens, Halophila tricostata and Halophila spinulosa were found in the offshore locations.
Water
Water quality monitoring was undertaken between 17 February and 30 May 2019. Real-time telemetered surface loggers were deployed at two trigger sites (Round Top and Victor Island) and two control sites (Slade Island and Freshwater Point). Benthic loggers were also deployed at both trigger sites. James Cook University’s ambient benthic loggers also remained at these four sites during the period.
Overall, dredging had little impact on turbidity or additional sampled parameters during the Dredge phase.
Sediment
Sediment Characterisation Study was completed in May 2016 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 current approved material relocation area.
Turtles and dugongs
No interactions or observations were recorded during dredging or placement operations.
Biosecurity
No marine pests identified during the activity.
Port of Karumba
Maintenance dredging
A total of 131,930m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 16 July 2019 to 10 August 2019. Dredging was undertaken at the Port of Karumba channel.
All works compliant and consistent with approval conditions. The volume dredged was well within annual forecast. The annual fee for the Environmental Authority was submitted during July and the annual return is to be submitted by 1 March 2020. No permit non-compliances, environmental incidents or complaints were reported.
Environmental assessments
Seagrass
The Port of Karumba Long Term Seagrass Long Term Monitoring Program annual survey was completed by James Cook University, TropWater, during November 2019, with a change in condition from very good, to very poor seagrass meadow condition and also declines in biomass. These changes are likely due to the prolonged effects of the early 2019 floodwaters within the southern gulf which persisted for nearly 3 months. Report under compilation and due early 2020.
Water
Water quality verification under the environmental management plans not triggered or required during the period. A significant wet season, and extended period of high turbidity waters over the southern gulf for February to April 2019 which preceded the 2019 dredge campaign.
Sediment
The Sediment Analysis Plan was implemented in 2015, with no noted events likely to have changed the contamination status of the outer channel area, with all past work confirming suitability for unconfined at sea placement under permit conditions.
Turtles and dugongs
No interactions or observations recorded during dredging or placement operations.
Biosecurity
Surveys of areas to be dredged as set out in the Sediment Analysis Plan in 2015 verified, with no reports of detections from regulators, of any actual or suspect material during the 2019 period.
Port of Townsville
Maintenance dredging
A total of 966,677m3 was dredged by the Trailing Suction Hopper Dredge Brisbane from 24 May 2019 to 9 June 2019 and 12 September 2019 to 24 October 2019. Dredging was undertaken at the Platypus and Sea channels, inner and outer harbour.
A Grab Dredge intermittently dredged 32,705m3 at berths 8 and 11 and the Ross River between 7 March 2019 to 5 December 2019.
There were no permit non-compliances and one reportable incident. Trailing Suction Hopper Dredge Brisbane reported a strike of a large loggerhead turtle resulting in a fatality during the September–October 2019 dredging campaign. No environmental complaints were reported.
Environmental assessments
Seagrass
Seagrass monitoring within Cleveland Bay was undertaken in September 2019. The report will be made available on the Port of Townsville Limited website once finalised and provided to the federal environment department as per the deed of agreement.
Water
Marine water quality monitoring was undertaken four times during 2019 at locations within or adjacent to the receiving environment (Ross River, Ross Creek, and Cleveland Bay). Samples were analysed for suspended solids, nutrients and metals. Results were similar to previous years, with the exception a peak event for suspended solids/turbidity/conductivity during the February 2019 flood event. Results have contributed to the Dry Tropics Partnerships for Health Waters – Waterway Health Report Card, which was released in April 2019.
Turbidity and light data was collected in 2019 at several underwater locations in Cleveland Bay. The National Environmental Science Program report shows that both turbidity and light appear to be influenced by climatic events, with seasonal variation evident. A number of real time water quality buoys were also deployed in Cleveland Bay to measure turbidity, temperature and electrical conductivity. The real time continuous data that is generated is helping to understand the ambient water quality conditions in Cleveland Bay and is also undertaken during maintenance dredging and placement activities. Turbidity levels were within the ambient levels throughout both maintenance dredging and placement activities. A water quality dashboard has been finalised to display the data on Port of Townsville Limited 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.
Turtles and dugongs
Trailing Suction Hopper Dredge Brisbane reported a strike of a large loggerhead turtle resulting in a fatality during the September–October 2019 campaign. Mitigation measures such as turtle deflectors were fitted and the procedure for dredging with regard to marine fauna was being followed during the works.
Biosecurity
Port of Townsville Limited is partnering with Biosecurity Queensland and other Queensland port authorities in an early warning pilot study.
Port of Weipa
Maintenance dredging
A total of 2,412,685m3 was dredged by the Trailing Suction Hopper Dredge Brisbane and Oranje from 4 June 2019 to 13 July 2019. Dredging was undertaken at the South Channel, inner harbour and berths.
Activities were compliant with state and federal approvals. 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 2 September 2019. Seagrass in all of the monitoring meadows appeared to be in good condition. This included the meadows located closest to port infrastructure and channels in the Embley River as well as seagrass areas further away from the port. There was some evidence of burning of seagrass leaves for the shallowest Enhalus meadows which typically occurs in these locations during spring low tides. The team observed the large growing Enhalus meadows flowering and also pollen released into the water during the survey. Evidence of dugong feeding activity in the Embley River seagrass meadows was recorded with dugong feeding trails observed in the meadows near Napranum. Overall seagrass meadows in the Port of Weipa remains in good condition.
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 2019 maintenance dredging program the turbidity was generally controlled by the natural conditions (tidal currents and wind/wave conditions), with higher turbidity occurring during spring tides and periods of larger waves and that the Port of Weipa 2019 maintenance dredging program did not influence the regional turbidity of the area.
Sediment
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 current approved material relocation area.
Turtles and dugongs
No interactions or observations were recorded during dredging or placement operations of the Brisbane. 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 the activity.
- Last updated 14 May 2024