This vessel was washed away from its mooring and foundered near the Boyne mouth. Photo taken the morning that Gladstone Ports Corporation resumed its major dredging project. Apparently turbidity readings showed it was safe to dredge.
Photos and article by John Mikkelsen
GLADSTONE Ports Corporation resumed its controversial major harbour dredging at the height of the Australia Day weekend floods, after a brief halt.
This was revealed by a GPC spokesperson in response to questions by The Queensland Telegraph following the re-appearance of the dredges Rotterdam and Al Mahar in harbour waters, which still appeared to be visibly murky from flood waters.
The Rotterdam is a fast, self-propelled trailing suction hopper dredge which dumps spoil at East Banks, off shore near Facing Island. It featured recently in a French TV Planet Hope news feature which focussed on the port developments at Gladstone and Abbot Point. Al Mahaar is a non self-propelled suction cutter dredge.
According to the GPC spokesperson, the dredges resumed operating at 6 am on Sunday, January 27, which was several hours before the Awoonga Dam spillway reached a record overflow height of 8.3 metres and houses downstream at Benaraby and low-lying sections of Boyne/ Tannum were inundated. More than 200 people sought refuge at emergency centres set up at Tanyalla in Tannum Sands and the PCYC in Gladstone. The overflow was about twice the height of the 2010 – 2011 event.
These are facts which we present without comment as historical context. Our questions and replies by the GPC spokesperson on Monday (February 4) are also presented without embellishment below.
“Q. What is the current status of dredging and turbidity?
A. Dredging stopped when harbour was closed by MSQ at 6pm Thursday 24 January and recommenced when harbour was opened with all dredges operating at 6am on Sunday 27 January. The initial response to the recent flood event in the Western Basin was extremely high turbidity (300+ NTU). Since the flows have slowed down the harbour is now a mixture of sea water and freshwater. The brackish water leads to the ‘flocculation’ of suspended particles and this causes suspended material that causes turbidity to reduce. This is most pronounced at the surface of the water column and is likely to be the reason for the low turbidity currently being observed in the basin. During our routine monthly monitoring last week we observed very high turbidity in the lower water column, further supporting the process previously described (Jan 2013 WQ report will be related in late Feb on http://www.westernbasinportdevelopment.com.au/environmental_reports/section/environmental). In the medium term this material will settle to the seabed, but if a high energy event occurs (i.e. storm event with strong wind) this material is likely to be resuspended into the water column. This process is not new to the western basin, or any other nearshore marine environment, and has been observed in the past. Turbidity and Light graphs are updated daily on the Western Basin Port Project website.
Q. Are there any other dredges operating and when did the Rotterdam actually re-commence dredging?
A. As above. (There is currently two dredges working on the WBDDP, the Rotterdam and the Al Mahaar. However, the Castor works periodically on the WBDDP. All this information is available on the website.
Q. Is it too early to tell how the floods have impacted the shipping channels here (and at Burnett Heads and Port Alma?)
A. At this time surveys are taking place to determine if the floods have impacted shipping channels. Once complete for Gladstone, Port Alma and Bundaberg will be done when safe to do so”.
Meanwhile, an environmental group has questioned how an astronaut saw and photographed the flood plumes on Tuesday, February 29 as published in last Saturday’s Telegraph while harbour monitors apparently showed no problems with turbidity.
Save the Reef said the dramatic pictures of the Queensland flood plume taken by astronauts showed a brown muddy harbour from outer space, “yet Gladstone Ports Corporation’s water quality monitoring program says it is safe to dredge the inner harbour.
“If Gladstone Ports Corporation’s light monitors say conditions are OK in a flood plume, there must be a problem,” according to spokesperson Dr Libby Connors.
She said Environment Minister Andrew Powell had expressed his concern that the plume would deposit sediment on seagrass meadows, severely damaging them.
‘Despite high turbidity, the light monitoring continues to indicate there is no problem but any lay person can see from the flood plume photos that light cannot reach the harbour floor and the seagrass will struggle to survive, “ she claimed.
“Save the Reef says that these events provide more data for UNESCO to question the capacity of the Queensland and Australian Governments to manage the Great Barrier Reef World Heritage Area.”
(The Federal Government reported to UNESCO on the management of the Great Barrier Reef World Heritage Area as requested on Friday, February 1. If UNESCO rejects the report, the Great Barrier Reef may be placed on the "In Danger" list).