MAY 2007

Chapter 7

Works at The Rip

Channel design

Few issues in the Independent Panel Report 2005 were as contentious as Channel Design, which elicited twenty-one recommendations. We submit that although there has been considerable data produced or re-produced the recommendations have not been addressed satisfactorily. The recommendations include highly technical concepts and it is clear that the Inquiry would have benefited from prior knowledge of the issues in assessing the proponent’s response to the recommendations.

It is not possible to clearly identify how each recommendation has been addressed within the SEES documentation. We request the Panel make a specific demand to the PoMC to address each recommendation in a separate document. The twenty one recommendations are listed separately at the conclusion of this chapter as Attachment 7.1

The economic case for the project is again predicated on unrestricted tidal access for vessels up to 14 metres draught1 however there is no compelling evidence that ships operating in a deepened channel would be any safer than was judged to be the case by the Panel in 2005.

The Independent Panel Report records the lengths the proponent went to in obfuscating about channel design and access - particularly at The Heads - including attempts to discredit submitters and witnesses and noted that the work relating to the engineering channel design did not form part of the exhibited EES documents2.

The proponent continued to assert that the economic case required 14 metre draught access at all states of the tide, however the exhibited documentation did not support this being possible. During the Panel Hearing considerable confusion was shown by the proponent’s legal and project team regarding what the actual proposal was for channel design and access at The Heads.

The SEES advises3 that the objectives of the Channel design process were to
  • Provide access for 14 metres draught vessels at all states of the tide
  • Meet maritime safety and navigational requirements
  • Minimise dredging volumes
We contend that these objectives have not been met in either the Great Ship Channel (entrance to Bay) or Bay and River channels, and dispute the proponent’s assertion that the acknowledged small operating related risk is purely a function of increased trade.

The SEES Assessment Guidelines recommend that the proponent draw on appropriate advice (eg: MSV) and the historical records (from MSV) of previous ship incidents in the channels and near The Entrance4. Although we are aware of a general letter of agreement from MSV5 that channel design is acceptable to MSV, we are unaware of data being made available on all previous shipping incidents as specified in the Guidelines. There is considerably more data and analysis in the SEES on channel design6 as it relates to operational efficiency of the Port Corporation than there is data and analysis of shipping incidents and risks as they might relate to the Bay or indeed the operational efficiency of the Port, Melbourne or the state of Victoria.  

If safe access at all states of the tide cannot be achieved we understand the project would not proceed. If the process of obtaining ‘all tide’ access involves costs which adversely impact the proponent’s cost-benefit analysis we assume the project would not and should not proceed. 

We believe the risks associated with a deeper draught vessel in a deeper rocky sided channel cannot outweigh the trifling economic benefits7 offered if the project was to proceed.

Great Ship Channel
Our concerns surround the risk of grounding or stranding of a vessel, most particularly an oil tanker at Port Phillip Heads, and the subsequent release of large quantities of oil. We contend that although the proponent may have assessed this as “low risk” this would pose disastrous environmental, financial and social consequences for the communities reliant on Port Phillip Bay, Western Port Bay and Bass Strait.

Panel Recommendation 2 states:

“Before the assessment of environmental effects, the proponent should be required to complete its evaluation of design and operational criteria for the Great Ship Channel in the Heads. An independent channel design expert should validate these. It will be necessary to:

  • Outline the percentage of metocean conditions and tide conditions for which the design criteria intend the great Ship Channel to be capable of transit by 14m draft vessels….”

The SEES advises a maximum acceptable transit failure of 1% for a single transit of a particular vessel in all metocean conditions8. We do not see a one in one hundred chance of any ship grounding as an acceptable risk to take for the purported economic benefits of $1.7 billion to the Australian economy over 22 years provided by this project.

Available data in the SEES provides little assurance that the safe navigation of 12.1 to 14 metre draught ships along the Great Ship Channel at all stages of the tide is likely.

We gather recent discussions between Blue Wedges advisers and Corporations project staff confirmed that the proposed design and operating parameters, set out in the SEES, have not changed from the design and the operating parameters, set out in the 2004 Environment Effects Statement (EES). This contradicts assertions made in the SEES, which state: “The CDP has been significantly refined since the EES. Environmental risks have been designed out, with remaining issues to be managed through the EMS and the EMP”9

Aside from the fact that the EMP is yet to be tabled in its final form, our advice is that the operating parameters in the Great Ship Channel are unchanged from the 2004 design. That being the case we have major concerns in relation to ships grounding and/or oil spills.

Simulation trials

Vessel transit simulation trials conducted from 2003 to 2006 are reported in the SEES.10 We note that metocean conditions were modified to be “less extreme” following the 2003 trials. Reducing metocean conditions to less extreme is questionable, especially given warnings of increased storms and storm surges in future as a result of global warming. The 2005 trials experienced two groundings. These were: 
  • A tanker travelling a too high a speed
  • Post Panamax container vessel at too high a speed
We submit that both of these scenarios are indeed possible. Both scenarios should be fully costed and put before the enquiry.

In the first two simulation trials, there were a total of 186 runs, from which 10 were familiarisation runs, 126 were successful and 50 runs were reported as either going aground or experiencing adverse results. In the third set of simulation trials the individual results were not detailed and disclosed. 

The results instil no confidence in the design and proposed operating parameters of the Great Ship Channel.

The PoMC has promoted the trials as a success. We suggest they were successful only in demonstrating that a grounding will occur at the Entrance.

Groundings and Oil Spills

We contend that navigation of large vessels with length up to 330 metre, beam up to 45 metre and draughts up to 14 metre at any stage of the tide and in all weathers into and out of Port Phillip Bay along the alignment of existing channels deepened to 17 metres will be more difficult and less safe than current operating parameters.

The consequences of such a grounding could render quite insignificant any other major maritime disaster that has occurred at any previous time, anywhere in the world.

The PoMC justifies the proposal on the grounds that the existing depths of water in the port’s channels restrict 30% of container ships from loading to their maximum draft. This figure is disputed elsewhere, however the SEES expends considerable effort in providing positive economic justifications for proceeding with the project.

It is claimed that if the channels are deepened to allow 14 metre draft vessels to use the port, Melbourne will be able to retain its pre-eminent position as the nation’s largest container port and that economic benefits will flow to all sections of the community.

What the SEES fails to address are the negative consequences: economically, socially and environmentally of an oil spill in the Bay.

The SEES reveals that in the event of the project proceeding, deeper draught, more heavily laden crude oil and product tankers will be able to use the port.

The maximum draught for ships transiting the entrance to Port Phillip Bay, through the Great Ship Channel, is presently restricted to 11.6 metre without tidal assistance, and 12.1 metre draught with the assistance of 1.5 metre of tide. 

We understand that all instances groundings of ships in Port Phillip Heads have occurred outside the boundaries of the Great Ship Channel. Due to strong cross currents in the Great Ship channel (7-8 knots) vessels often crab through the channel. The bow and stern may have deviated considerably from the mid line of the vessel, thus bringing the bow and stern considerably closer to the sides of the channel. Larger less manoeuvrable vessels in the metocean conditions often encountered at The Entrance are more likely to loose steerage. If the bow or stern of a 14 metre draught vessel strays outside the Great Ship Channel it will ground on any part of the side channels which are at 14 metres depth.

We also understand that the International Guide for the Design of Approach Channels advises that cross currents between 1.5 knots and 2.0 knots are strong. The Guide ceases to provide empirical rules for approach channel widths where cross currents exceed 2.0 knots, stating that in such situations a detailed assessment and design is required.

We are advised by the PoMC that they have undertaken detailed assessment and design, however as there are no empirical rules for the particular set of conditions which is the norm at The Heads and in the Great Ship Channel we are reliant on the design parameters produced by the proponent. The proponent has a vested interest in ensuring the project proceeds and that 14 metre draught vessels can be accommodated in the Port. 
Our advice is that concerns put to the PoMC regarding potential grounding of 12.1 to 14 metre draught ships in the Eastern and Western Ship Channels alongside the Great Ship Channel have been dismissed by the proponent. We also note that the proponent concedes this size container vessel may not be seen in the Port for many years to come.

In March 2007 The Age reported that the Port of Melbourne has conceded it could be years before larger ships use the channel, because current trade volumes were too small to warrant larger vessels. Port of Melbourne Corporation chief executive Stephen Bradford said current trade volumes were too small to warrant larger vessels. "It's a bit like having a B-double (truck) and only using half the B," Mr. Bradford said. "It doesn't make any sense. The channel deepening is a 30-year project, so will the 14-metre draught vessels arrive on day one? No."11

Unfortunately this attitude avoids consideration of:
  • Transit through Port Phillip Heads of any deeper 12.1 to 14 metre draught oil tankers and bulk ships which might use the Port immediately if the project was completed
  • Oil tankers have the greatest potential for spilling large quantities of oil.
We further understand that the PoMC has received some advice from Sea Pilots that 12.1 to 14 metre draught ships should be limited to transit through the Heads to the times of slack water - four hours per day. This requires further investigation. If so, the economic imperative of an all tides access for 14 metre draught vessels will not be achieved and the economic justifications for the project have no foundation.

The PoMC has delivered a project design which it claims can be complete within two years.
At the very least then we ask why the unseemly haste to proceed with this project when there are recorded and acknowledged risks for shipping at The Entrance and it is conceded that there is no immediate demand for deeper water?

Peer Review

We note peer review of Channel Design Entrance Depth12 records that did not receive copies of technical briefs for the SEES guidelines and EES Panel recommendations relating to Channel design. SKM conclude that it is not possible to predict with accuracy motions of individual vessel transits through the Heads.

Risk Assessment

Royal Haskoning13 were not required to assess the magnitude of the potential consequences of a grounding or oil spill at The Entrance.

Royal Haskoning were only required to assess the likely occurrence of a 12.1 to 14 metre draught ship grounding and stranding in the Heads.

In 2006 four vessels with draughts less than 11.6 metre, deviated outside the Great Ship Channel. It is the consequence of what would have occurred had these ships been of a draught between 12.1 and 14 metres which is the important issue and which has not been adequately assessed: environmentally, socially or economically.


There is no urgency for deep water access to the Port.

The risks associated with the proposed operating parameters of the Great Ship Channel have not been adequately assessed.

The information supplied to the 2004 Panel by Capt. Frank Hart on behalf of Blue Wedges in September and November 2004 remains valid and largely unaddressed and unanswered. The Panel noted at that time that the proponent did not always challenge let alone disprove the factual basis of significant bodies of Capt. Hart’s material14.

Capt. Hart will re-submit material to this Panel in 2007.

Dredge methods and scheduling

Dredge scheduling for The Entrance and South of the Bay indicates that for at least 16 months the Bay and its inhabitants will be exposed to noise, turbidity and sedimentation.

Works at The Entrance are now scheduled to take up to eight months, and the untested and highly percussive hydrohammer may be used at any time throughout that period. The presence of a hydrohammer and dredge in the south of the Bay and The Entrance from eight to 16 months has implications for migrating species, seabirds, fish and larvae. 

It is acknowledged that reduced fish stocks and turbidity will affect various seabird species for up to two years, but once the risk assessment methodology is applied, this risk is rated as minor. We dispute that a two year interruption to breeding cycles of the numerous species affected would be recovered within the short time frame assessed by the risk analysis. We remind the Panel of the advice of Dr. Matt Edmunds 

“The information provided above on linkages between organisms within habitats and at wider spatial scales was largely derived from basic marine processes described elsewhere. There is currently little information that quantifies the actual strength of the linkages for Port Phillip Bay”15

Although the PoMC does concede the dive industry might suffer some financial loss as a result of the Corporation’s damage to its workplace, it does not concede that compensation is indicated. The proponent does not however concede that any other Bay related business might suffer measurable financial consequences in spite of the vast amount of data that it has produced recording measurable impacts on numerous sectors of the environment of Port Phillip Bay. Our membership is strongly of the view that Bay related businesses will be affected by both the presence of the dredge in the Bay and its effects, and intends to pursue the proponent for compensation should the project proceed.


In his March 2005 statement16, then Minister for Planning Rob Hulls stated that the EES Panel has identified several ‘threshold issues’ affecting project feasibility which subsequently resulted in the trial dredging.  However, some of the issues raised have still not been proven to be able to be done, including the performance of the Hydrohammer.

The Hydrohammer was not tested during the trial. We refer to the comments by the late Keith Burren, former consulting engineer and board member of the Melbourne Port Corporation, 1999-2003, in his submission to the EES Panel Hearing:17

“The accuracy with which the hammer can be positioned and maintained on the seabed under varying sea and tidal states remains to be demonstrated.  This is a particular consideration given the frequency at which the vessel must leave station on each tide and subsequent re-positioning itself to an accuracy ensuring continuation of rock breaking into sizes not exceeding the required 40-50 cm.

At present time, the prospects for successful application of the HYDROHAMMER may perhaps be fairly compared to attempting micro-surgery upon a patient on a constantly moving table”.


The Trial

The major rockfall incident which occurred at The Heads during the 2005 trial dredge was dismissed by the PoMC as minor. Subsequent Media Releases then promoted the Trial dredge at the Entrance a success. We now know that 6,000 cubic metres, approximately 9,900 tonnes of rock, habitat, coral and sponges cascaded uncontrolled down the canyon wall. In spite of this, PoMC still describe their trial dredge a success!

In spite of the assurances from PoMC, prior to the trial members of the Port’s Public Stakeholder Advisory Committee (PSAC) expressed concerns that the proposed dredging methodology might cause rocks to fall uncontrollably into the Canyon. PoMC assured PSAC members that given the technological skills of Royal Boskalis the dredging contractor, and the protection of the EMP that eventuality the risk of a rockfall occurring was highly unlikely. Unfortunately PSAC members were proved correct, and the PoMC proved incorrect, their best practice technology and EMP left in tatters.

The Trial Dredge Deep Reef Impact Report18 quantitatively surveyed a small proportion of the Canyon Wall. At 17 metres depth, where most recreational diving occurs, over 90% of the area surveyed had sustained damage It was found that falling rocks caused damage to 57 metres depth – however formal survey activity ceased at 57 metres depth. Rocks fell, and are still lying at the bottom of the canyon - a depth of approximately 100 metres.  We estimate around 180 B Double truck loads of rock fell uncontrolled into a world class diving site, destroying outstanding scenery and habitat. Some fell into the adjacent Marine National Park. Would we condone this type of environmental damage in on land?

During the trial, the proposed dredge area was located 50 metres back from the canyon edge. The actual area dredged proved to be much closer to the canyon edge, with uncontrolled overburden falling into the canyon. This was a relatively simple site, with only one edge (150 metres long as a drop-off) and that edge perpendicular to the current. 

The Proposal

A total of 550,000 cubic metres of rock is planned for removal. It seems the PoMC is still unsure of how much “hard’ rock might be encountered. This has led to the PoMC not being able to predict how much they may need to use the hydrohammer19. We contend such high levels of uncertainty about what might be encountered, where it might be encountered, which equipment might be used and for what period means that the PoMC’s predictions of rockfalls are assumptions at best.

The SEES predicts approximately 4,300 cubic metres of rockfall into the canyon and Marine Park20. The SEES consultants predictions for where rockfalls will occur21 are based on this estimate.

The proposed area to be dredged has vertical drop offs on three sides, with two sides perpendicular to the current and one side parallel to the current. Under these much more complex conditions, we contend that rockfall would occur at least the same rate as did occur in the simpler dredging exercise during the trial. The greater degree of difficulty for the proposed site most likely would far exceed the established rate of rockfall.

The exposure area in horizontal length (possible length for rockfall) is almost 7.5 times the length encountered during the trial. Therefore:

7.5 x 6,000 cubic metres = 45,000 cubic metres of rockfall predicted

The volume of rock proposed to be dredged is almost 20 times the volume moved during the trial.  The fall rate on the trial dredge was 20% of the volume. Therefore:

20% of 550,000 cubic metres (proposed rock removal) = 110,000 cubic metres of rock fall predicted

Both of these calculations are based on the same degree of difficulty which the trial dredge encountered. We have already described that there will be a much greater degree of difficulty in dredging the proposed area.

Based on past dredging performance, it is reasonable to expect at least double the rate of rockfall. The proposed revised dredging methodology (Option 3) does not give sufficient detail as to how any reduction of rockfall would be achieved. 

The dredge was not able to be positioned accurately in The Rip whilst carrying out the Trial, as evident from data within the EPA’s Trial Dredge Independent Audit Report22 which shows multiple excursions (69 events) of the drag head outside the defined project area. What is the likelihood of the adjacent Marine Parks being spared damage when it is proposed to remove twenty times the volume removed during the trial, much under more difficult circumstances than during the trial?  What is the PoMC’s fall-back position if all the rock cannot be removed by either the TSHD and/or the hydrohammer?  What are the environmental consequences of that eventuality?

Dredging option analysis

Analysis of the PoMC’s strategies for reduction of rockfall23 confirm our view that the method chosen is primarily one of convenience rather than environmental. The PoMC has however allocated considerable resources to portraying that there has been technical achievement in developing a strategy to reduce rockfalls when in reality if they wish to remove the top of the plateau, given the set of ocean and topographical conditions they faced, there was no other option. Thus much of Technical Appendix 21 appears to be a deliberately constructed study with a known outcome, rather than serious research into alternative methods. 

The entire analysis appears largely to have been back engineered to justify the system used in the trial dredge, and supposedly incorporates some minor improvements to the drag head. These improvements are yet to be tested under working conditions, having been developed and tested in the laboratory. 

The major consideration for controlling rockfalls on the Nepean Bank, stopping rocks falling towards the Marine Park is touted as a strategy when it is no more than the common sense way to dredge in that particular metocean and sea-bed topography configuration.

The proposal is to take North-South passes leaving the extreme West, closest to the Marine Park, until the last. This strategy is dictated by the current and any variation from that is not a design option – it is the only option. We believe that in spite of considerable writings describing laboratory studies, the proposed dredging method is fixed by variables beyond the control of the PoMC.

The proposed method will not stop rocks falling over the North and South face of the Plateau, and will simply delay the rocks falling off the West face until the last dredging runs are taken. The outcome however is not expected to have any real effect on reducing rock fall. As verified by Dr. Matt Edmunds and consultants DHI in Technical Appendix 21, under normal ocean conditions rocks move approximately in a north or south direction, not westerly towards the most sensitive edge identified by PoMC. Furthermore the strategy does not explain clearly how it proposes to deal with rocks that fall at the end runs of the North-south South crossing of the Plateau. 

See: Rip Bank (Plateau) below
Our analysis of how rockfall will occur during dredging of the Plateau, marked in red will be described in further detail during our verbal presentation.

Past performance
Under FOI, Blue Wedges requested various documents relating to the Trial dredge. It appears that contrary to their public statements, PoMC knew about the rockfall at The Entrance well before they stopped dredging. In their Media Release dated 2nd September 2005 PoMC indicate they only discovered the rockfalls on the day that they stoped dredging in The Entrance. The PoMC Trial dredge Update Weekly Update of 22nd August 2005 is also relevant.
  • PoMC’s Media Release of 2nd September 2005 states that the rockfall “came to light on Monday” which was 29th August 2005.
  • Monday 29th August co-incided with the final date for the 2 weeks of dredging at The Entrance
  • Divers were excluded on 1st September 2005 – for a period of a further 6 weeks - without prior warning
See Media Release at Attachment 7.2 and Weekly update at Attachment 7.3

Decision Log data for the trial dredge period obtained under FOI shows:
  • First reference to a rockfall incident on 19th August 2005.  It states “PDS indicates rockfall on intermediate reef and maybe on deep reef”
  • Entry 21st August 2005 reads: “Report AME (Australian Marine Ecology) shows minor rockfall evidence above and no below -20 metres. Info via email extract”. Decision: “Work method back to normal. Concentrate on highs and ledges”.
  • Another entry elsewhere reads: “Rockfall trigger point E13 activated. Resolved on Monday 22nd August”
  • Another entry dated Thursday 18th August 2005 indicates Performance Standard E21 (Underwater Noise) may not have been achieved.
  • The PoMC Trial Dredge Weekly Update as at 22nd August 2005 however states “ No triggers or thresholds have been reached and all performance standards have been within the strict targets set down under the Environmental Management Plan”
Apparently for Rockfall and Noise Performance standards at least PoMC may not have been within the strict targets set down in the EMP. Clearly PoMC knew about rocks falling, and that they had activated a Rockfall trigger point well before their weekly update of 22nd August 2005, well before their Media Release of 2nd September 2005 and well before they stopped dredging.  

However until Blue Wedges supporters arrived at the scene on 1st September 2005 to take a dive, PoMC had not bothered to announce the rockfall incident, in spite of it having activating a trigger point, and causing damage, from 19th August 2005 – damage recorded in their own notes.  According to the Media Release however, they learned about falling rocks on Monday 29th August – after they had completed dredging at The Entrance.


The PoMC appears to have deliberately misled the public about their compliance with the EMP and extent of damage caused during the trial so as to continue works without impediment. Why should we expect any different behaviour from the Corporation if the project proceeds than was evident during the trial?

The consultants’ 3-D representations of rockfalls into the canyon and Marine parks  are based on the assumed volumes of rockfall as calculated by the PoMC.

We predict that much greater areas of the canyon and Marine Park will be affected in the short and long term by uncontrolled rockfall. When the rocks fall, some will drop onto ledges. Rocks will either stay put and smother existing habitat or migrate further down the canyon in response to currents. The extent of potential ongoing damage is not adequately represented in the modelling.

This means much greater and longer lasting environmental damage and habitat destruction and much greater damage to the Dive Industry’s work place than acknowledged. It also means the potential for much greater damage to the Bay and its inhabitants and other Bay users and related businesses. Given the outcome from the trial, this eventuality should be costed as part of economic modelling for the project.


  [1] SEES Main Report Chapter 4 Page 5, and Technical Appendix 8 Page 15
  [2] Independent Panel Report 2005 Chapter 7 Page 93-105
  [3] SEES Executive Summary Page 12
  [4] SEES Main Report Chapter 6 Page 8
  [5] Technical Appendix 17 MSV Letter dated 8th January 2007
  [6] SEES Technical Appendix 9 Port of Melbourne Channel Capacity
  [7] PriceWaterhouse Coopers Economic Analysis of the Port of Melbourne March 2007
  [8] SEES Main Report Chapter 6 Page 32
  [9] SEES Executive Summary Page 34
  [10] Technical Appendix 10
  [11] The Age Toxic Plume may reach Docklands March 23rd 2007.
  [12] SKM Technical Appendix 18
  [13] Technical Appendix 15
  [14] Independent Panel Report Page 96
  [15] Technical Appendix 47 Page 36
  [17] 6 December 2004 (para 1.5.3).
  [18] Edmunds et al March 2006
  [19] SEES Main Report Chapter 7 Page 31
  [20] SEES Main Report chapter 7 Page 35
  [21] Technical Appendix 52
  [22] EPA Port of Melbourne Corporation Trial Dredge Program Independent Assessment (GHD)November 2005 Appendix E Page 2
  [23] Technical Appendix 21
  [24] Technical Appendix 52 Figures 26, 27 and 28

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