PoMC's tactic of presenting last minute data on long-term damage at The Entrance caused by erosion, scour and build up of mounds of mobile material in the Great Ship Channel did not work. Inquiry chair Dr. Allan Hawke has invited further submissions on this critical issue for shipping safety and changes to the Bay's ecosystems. Please take the opportunity to respond - Read on!

Contrary to what you hear and read in the media, the Channel Deepening Project is NOT a fait accompli.


Very serious outcomes from the August 2005 Trial Dredge Program (TDP) were only released to the SEES Inquiry last week – on the second last day of the hearings. So serious are they that the Inquiry Chair saw fit to call for further public submissions on this new evidence.


The time frame is severely limited – now only 7 days. But it is critical that in that time each and every one of us respond. Your reply does matter. PLEASE ACT NOW.

The deadline is 10am Monday 13 August.


Here are the recent facts. New submissions are meant to be to this new information only, so a lengthy reading of earlier material is not required:


1. The Trial Dredge Program of August 2005 was not a success as claimed. Damage done at the Entrance is much greater than admitted at the time.


  • The volume of rock which fell after trial dredging was greater than claimed
  • The rocks fell to greater depths than claimed
  • They were not “gathered” by the dredge
  • Rock at the Entrance is continuing to disintegrate and mobilize, causing further scouring of the channel.


2. That was not the “end of the matter”.


  • There has been delamination and mobilization of rock layers - slabs up to 3m2 and 400mm thick can be lifted by current and swell (This was NOT expected and is raising issues of long-term stability)
  • PoMC claims that a hard layer of rock at 22m depth will limit further scour, but scouring to 25m depth has occurred in some places
  • On 30 July PoMC declared scouring might continue for 30 years (coincidentally the length of the project), but it is not clear that there is any time limit to scouring as no evidence is provided.


3. What we know (or have been told) up to the present.


  • Modelling of the Entrance ship channel is now being done on the basis of 22m depth to take account of scour (compared with the original max depth of -19m). 
  • Extensive further research and analysis is needed to determine the effects of dredging into this rock which is prone to cracking and erosion beyond modelled “predictions”
  • The combined effects of further rock scour, and rock delamination, have not been adequately assessed.
  • How much of the rock disintegration is due to dredging and how much is due to the natural susceptibility of the rock has not been described.
  • The further influence of tidal currents at 22m and below is not known.
  • The effects at shallower levels of extreme storm events are unknown
  • The ability of the PoMC to periodically “clear up” extra rock which will result is also unknown, despite new arrangements (Tuesday 31 July)
  • All impacting factors have not been put in to the model which is meant to show what the likely outcomes will be (Raisbeck SKM Report). The model only looked at the effect of slope and gravity on mobile rock


4. What concerns and questions result?


  • How much more will the ongoing clearing of rock now cost?
  • Is the “hard cap” layer at 22m depth a real constraint to further erosion?
  • Severe storm events are most likely to mobilise rock, yet PoMC has not proposed to have a rock clean-up after significant storms.
  • Up to 2 metres build up of this newly mobile material is predicted within the Great Ship channel. These “mounds” will pose shipping hazards, decreasing safety for passage through The Heads, an already treacherous waterway.
  • Will there be a thorough examination of likely impacts of rock fall, rock scour, and extra flow of water through the Heads (likely to be more than double original estimates).
  • How much damage to the Marine Parks is now apparently acceptable to PoMC and government?
  • What “flow-on effect” will this have on tidal heights, sea level rise, coastal erosion, sand and sediment movement etc in and around Port Phillip?
  • How will the flushing time of the Bay change and what will be the consequences for a range of ecosystems?
  • Given the damage to environmental assets predicted, this should mean a full new Environmental Effects Study (EES)
  • And, given the damage to environmental assets predicted, this should mean a new economic analysis of the case for the project


Write a response (brief and to the point would be best) and send it to the address below. NOTE they still want them in hard copy, not email, but if you have any queries, we suggest you address them to Michael Crossman


The DSE website link holds more information, including this message:


Submissions must be in writing and posted to:

Planning Panels Victoria
Channel Deepening Project
PO Box 500
VIC 8002

Submissions must be received by 10:00 am Monday 13 August 2007.



FAX. NO. 9637-9700


Michael.Crossman@dse.vic.gov.au or phone him on 9637-9692.

Link to relevant page is




or go to www.dse.vic.gov.au then click Planning, then Environment Assessment, then Port Phillip Channel Deepening.

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