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Resuspension and clearing of dredge spoils after dredging, Cleveland Bay, Townsville, north Queensland

Australian Institute of Marine Science
Australian Institute of Marine Science (AIMS)
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ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rfr_id=info%3Asid%2FANDS&rft_id=https://apps.aims.gov.au/metadata/view/49b82a0e-47ce-4e1f-ab4f-6b10096e4c37&rft.title=Resuspension and clearing of dredge spoils after dredging, Cleveland Bay, Townsville, north Queensland&rft.identifier=https://apps.aims.gov.au/metadata/view/49b82a0e-47ce-4e1f-ab4f-6b10096e4c37&rft.publisher=Australian Institute of Marine Science (AIMS)&rft.description=Field studies of the effects of dredging the 8km long Townsville navigation channel (Platypus Channel) were carried out in May 1989. The suction dredge was followed by a research vessel and the spoil plume, which formed in the lee of the dredge, was marked using a near-bottom sail drogue. Vertical profiles of temperature, salinity and suspended sediment concentration (SSC) were obtained next to the drogue. Cross sections of the suspended sediment density stratification in the water column next to the drogue and along transects perpendicular to the track of the dredge during dredging, were recorded using an acoustic sounder.In the laboratory, the settling characteristics of a composite sample of muddy silt from four areas of the harbour, that are dredged were investigated. Sediment was added to a column and subjected to turbulence. Floc sizes were measured and vertical profiles of SSC were obtained. The purpose of this research was to identify optimum conditions for dredging, that would result in the least damage to environmentally sensitive areas. Research focused on the fate of sediments, which were resuspended due to mechanical disturbance of the bottom during the process of dredging, the dredge's turbulence and the sediment released from the dredge's surface overflow. This research was undertaken to address concerns relating to the impacts of dredging and the dumping of dredge spoil in Cleveland Bay. Issues of concern included the possible effects of siltation on nearby coral reefs, seagrass beds and beaches and the potential effect of toxic metals carried in mud from Townsville Harbour.Maintenance and Update Frequency: notPlannedStatement: Statement: Field Studies:1. Depth, Temperature, Salinity and SSC: Vertical profiles of temperature, salinity and suspended sediment concentration were measured using the mud probe, which used Aanderaa sensors to measure depth, salinity and temperature. The probe also included an Analite optical fibre backscattering nephelometer, for the measurement of suspended sediment concentration (see Wolanski EJ, Chappell J, Ridd P and Vertessy R (1988) Fluidization of mud in estuaries. Journal of Geophysical Research 93: 2351-2361).2. Acoustic Monitoring:Acoustic monitoring was carried out at a frequency of 210 kHz using a Deso-10 acoustic sounder and a JRC:JFV-80 acoustic sounder.Laboratory Studies:1. Column:The column used in the laboratory study was a polymethylmethacrylate cylinder, with an internal diameter of 10cm and a height of 140cm. To generate turbulence, 1cm wide rings spaced 2cm apart, were oscillated at different speeds using a stroke of 0.75cm. Natural seawater (34ppt) was used in the column.2.Floc sizeFloc size was measured using a horizontal-axis microscope at various depths to view through the column.3. SSCVertical profiles of suspended sediment concentration were obtained by using a profiling Analite optical fibre back-scattering nephelometer.&rft.creator=Australian Institute of Marine Science (AIMS) &rft.date=2025&rft.coverage=westlimit=146.798098; southlimit=-19.26588; eastlimit=146.898328; northlimit=-19.15273&rft.coverage=westlimit=146.798098; southlimit=-19.26588; eastlimit=146.898328; northlimit=-19.15273&rft_rights=Creative Commons Attribution-NonCommercial 3.0 Australia License http://creativecommons.org/licenses/by-nc/3.0/au/&rft_rights=Use Limitation: All AIMS data, products and services are provided as is and AIMS does not warrant their fitness for a particular purpose or non-infringement. While AIMS has made every reasonable effort to ensure high quality of the data, products and services, to the extent permitted by law the data, products and services are provided without any warranties of any kind, either expressed or implied, including without limitation any implied warranties of title, merchantability, and fitness for a particular purpose or non-infringement. AIMS make no representation or warranty that the data, products and services are accurate, complete, reliable or current. To the extent permitted by law, AIMS exclude all liability to any person arising directly or indirectly from the use of the data, products and services.&rft_rights=Attribution: Format for citation of metadata sourced from Australian Institute of Marine Science (AIMS) in a list of reference is as follows: Australian Institute of Marine Science (AIMS). (2009). Resuspension and clearing of dredge spoils after dredging, Cleveland Bay, Townsville, north Queensland. https://apps.aims.gov.au/metadata/view/49b82a0e-47ce-4e1f-ab4f-6b10096e4c37, accessed[date-of-access].&rft_rights=Resource Usage:Use of the AIMS data is for not-for-profit applications only. All other users shall seek permission for use by contacting AIMS. Acknowledgements as prescribed must be clearly set out in the user's formal communications or publications.&rft_subject=oceans&rft.type=dataset&rft.language=English Access the data
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Creative Commons Attribution-NonCommercial 3.0 Australia License
http://creativecommons.org/licenses/by-nc/3.0/au/

Use Limitation: All AIMS data, products and services are provided "as is" and AIMS does not warrant their fitness for a particular purpose or non-infringement. While AIMS has made every reasonable effort to ensure high quality of the data, products and services, to the extent permitted by law the data, products and services are provided without any warranties of any kind, either expressed or implied, including without limitation any implied warranties of title, merchantability, and fitness for a particular purpose or non-infringement. AIMS make no representation or warranty that the data, products and services are accurate, complete, reliable or current. To the extent permitted by law, AIMS exclude all liability to any person arising directly or indirectly from the use of the data, products and services.

Attribution: Format for citation of metadata sourced from Australian Institute of Marine Science (AIMS) in a list of reference is as follows: "Australian Institute of Marine Science (AIMS). (2009). Resuspension and clearing of dredge spoils after dredging, Cleveland Bay, Townsville, north Queensland. https://apps.aims.gov.au/metadata/view/49b82a0e-47ce-4e1f-ab4f-6b10096e4c37, accessed[date-of-access]".

Resource Usage:Use of the AIMS data is for not-for-profit applications only. All other users shall seek permission for use by contacting AIMS. Acknowledgements as prescribed must be clearly set out in the user's formal communications or publications.

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Field studies of the effects of dredging the 8km long Townsville navigation channel (Platypus Channel) were carried out in May 1989. The suction dredge was followed by a research vessel and the spoil plume, which formed in the lee of the dredge, was marked using a near-bottom sail drogue. Vertical profiles of temperature, salinity and suspended sediment concentration (SSC) were obtained next to the drogue. Cross sections of the suspended sediment density stratification in the water column next to the drogue and along transects perpendicular to the track of the dredge during dredging, were recorded using an acoustic sounder.In the laboratory, the settling characteristics of a composite sample of muddy silt from four areas of the harbour, that are dredged were investigated. Sediment was added to a column and subjected to turbulence. Floc sizes were measured and vertical profiles of SSC were obtained.
The purpose of this research was to identify optimum conditions for dredging, that would result in the least damage to environmentally sensitive areas. Research focused on the fate of sediments, which were resuspended due to mechanical disturbance of the bottom during the process of dredging, the dredge's turbulence and the sediment released from the dredge's surface overflow.
This research was undertaken to address concerns relating to the impacts of dredging and the dumping of dredge spoil in Cleveland Bay. Issues of concern included the possible effects of siltation on nearby coral reefs, seagrass beds and beaches and the potential effect of toxic metals carried in mud from Townsville Harbour.

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Maintenance and Update Frequency: notPlanned
Statement: Statement: Field Studies:1. Depth, Temperature, Salinity and SSC: Vertical profiles of temperature, salinity and suspended sediment concentration were measured using the "mud probe", which used Aanderaa sensors to measure depth, salinity and temperature. The probe also included an Analite optical fibre backscattering nephelometer, for the measurement of suspended sediment concentration (see Wolanski EJ, Chappell J, Ridd P and Vertessy R (1988) Fluidization of mud in estuaries. Journal of Geophysical Research 93: 2351-2361).2. Acoustic Monitoring:Acoustic monitoring was carried out at a frequency of 210 kHz using a Deso-10 acoustic sounder and a JRC:JFV-80 acoustic sounder.Laboratory Studies:1. Column:The column used in the laboratory study was a polymethylmethacrylate cylinder, with an internal diameter of 10cm and a height of 140cm. To generate turbulence, 1cm wide rings spaced 2cm apart, were oscillated at different speeds using a stroke of 0.75cm. Natural seawater (34ppt) was used in the column.2.Floc sizeFloc size was measured using a horizontal-axis microscope at various depths to view through the column.3. SSCVertical profiles of suspended sediment concentration were obtained by using a profiling Analite optical fibre back-scattering nephelometer.

Notes

Credit
Wolanski, Eric J, Dr (Principal Investigator)

Modified: 19 09 2025

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146.89833,-19.15273 146.89833,-19.26588 146.7981,-19.26588 146.7981,-19.15273 146.89833,-19.15273

146.848213,-19.209305

text: westlimit=146.798098; southlimit=-19.26588; eastlimit=146.898328; northlimit=-19.15273

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Other Information
Ocean disposal of dredge spoils and sewage sludge: Wolanski EJ and Gibbs RJ (1995) Ocean disposal of dredge spoils and sewage sludge. pp. 611-630. In: Cheremisinoff PN (ed) Encyclopedia of Environmental Control Technology. Vol.9. Geotechnical applications, leak detection and treatment options. Gulf Publishing Company. 1137 p.

local : articleId=2621

Settling of ocean-dumped dredged material, Townsville, Australia: Wolanski EJ, Gibbs RJ, Ridd P and Mehta A (1992) Settling of ocean-dumped dredged material, Townsville, Australia. Estuarine Coastal and Shelf Science 35: 473-489.

local : articleId=2602

Resuspension and clearing of dredge spoils after dredging, Cleveland Bay, Australia: Wolanski EJ and Gibbs RJ (1992) Resuspension and clearing of dredge spoils after dredging, Cleveland Bay, Australia. Water Environment Research 64: 910-914.

local : articleId=2424

Identifiers
  • global : 49b82a0e-47ce-4e1f-ab4f-6b10096e4c37