News

Ignorance over dredging no longer an excuse

Aerial view of Curtis Island, LNG sites. Dredging and Fishermans landing in the background.
Aerial view of Curtis Island, LNG sites. Dredging and Fishermans landing in the background. Brenda Strong

AN ENVIRONMENTAL activist says a new report that shows turbidity levels from dredging operations travelled twice as far as predicted proves further dredging impacts cannot be blamed on ignorance.

Plumes of sediment materialising from dredging operations in Gladstone harbour were found to have travelled almost twice the distance as predicted, according to satellite imagery put together by two James Cook University scientists.

The Western Basin Dredging Project, undertaken by Gladstone Ports Corporation from 2011-13, has faced international scrutiny for flaws exposed in the removal of 22 million cubic metres of sediment.

While the GPC would not comment on the report, it assured the community all issues relating to dredging within the Western Basin at the Port of Gladstone had been resolved and they did not present an ongoing threat to the environment.

Occurrence maps corresponding to the number of times (in percentage) any given pixel of the GBR was covered by values higher than 5 mg.l-1 during the spring of 2011. Photo Contributed
Occurrence maps corresponding to the number of times (in percentage) any given pixel of the GBR was covered by values higher than 5 mg.l-1 during the spring of 2011. Photo Contributed Contributed

Dr Caroline Petus and Dr Michelle Devlin used satellite technology to examine sediment dispersion, producing a report that found during the spring of 2011, when fish health issues were reported, the threshold for turbidity in the ports waters exceeded all other respective years and in comparison to historical mean figures.

Famously, such problems in turbidity were linked by the GPC to natural flooding events.

However, the report proceeds to dispel notions that sediment plumage was caused by tidal events, claiming values recorded were vastly over average patterns, even during flooding.

Additionally, the report utilised Remote sensing imagery (MODIS) in order to differentiate the impacts of dredging activities from sediment, which could be attributed to natural causes like river discharge and tide influences.

As a result of the comprehensive research encapsulated in the report, proof that turbidity levels had reached up to 35km from the initial dredging operations are raising concerns for environmentalists.

Jane Bialst, an environmental activist, said the proof was in the paperwork.

"It may be a little controversial to say, but I for one am thankful for the disaster that has unfolded in Gladstone," she said.

The dredging company responsible for the Western Basin project scrambled to repair damaged weir boxes, which leaked sediment into Gladstone Harbour.
The dredging company responsible for the Western Basin project scrambled to repair damaged weir boxes, which leaked sediment into Gladstone Harbour. Contributed

"The enormous disruption to the Gladstone marine environment has meant that we, as environmentalists, were not wrong. We weren't crazy and we weren't trying to push our agenda."

If the government proceeds with further dredging operations, they can no longer claim ignorance.

She said the proposal to do the same dredging operations in Abbot Point and Hay Point, within 50km of the Great Barrier Reef would never be a good idea.

"If the government proceeds with further dredging operations, they can no longer claim ignorance," she said.

Gladstone Ports Corporation issued the following statement to The Observer in regards to the report.

"Gladstone Ports Corporation has not reviewed the report presented by Petus and Devlin and therefore cannot make comment as to its validity," the statement read.

"GPC intends to, and will, incorporate the lessons learned from the Independent Review of the Port of Gladstone into its future practices, and is committed to working alongside the federal and state governments to implement its recommendations."

PETUS/DEVLIN REPORT

  • During the spring of 2011 the turbidity levels in Gladstone harbour exceed all previously recorded data.
  • In the same season, sediment was observed as far as 35km from the main dredging site.
  • Graphics (pictured) show Port Curtis was experiencing greatly elevated levels of sediment 80% of the time during the spring of 2011.
  • The sediment plumes affected marine environments as far away as Rodd's Peninsula during the same period.
Predicted Dredge Plume Source: Western Basin Dredging EIS Appendix K Numerical Modelling Studies' p.4-16.
Predicted Dredge Plume Source: Western Basin Dredging EIS Appendix K Numerical Modelling Studies' p.4-16. Contributed

Topics:  dredging environment gladstone harbour gladstone ports corporation sediment



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