Part 1 of 2





MAY 2007

Chapter 5

Toxicity and Public Health Issues

Executive Summary

It is clear from the SEES report that the PoMC proposes to disturb and dump extremely large volumes of contaminated sediment, much of which is highly contaminated.  The quantity of contaminated sediment appears to have been under-estimated.  Particularly the sediments in the Port Melbourne Channel have been classified as “uncontaminated”.  However according to Irvine the peer reviewer, this assessment is not borne out by the facts. 

Many of the EES panel recommendations have not been adhered to. Proper historic analysis of past contamination was not carried out.  The grid sampling technique that was used was neither random, nor was it targeted based on historical data, despite panel recommendations that targeted sampling should occur.  There was very little sampling of the deeper, consolidated sediments, so it is likely that the toxicity of the deeper sediments has also been under-estimated.  There has been no attempt to separate out the most highly contaminated sediments from the less contaminated sediments.  If this had been done, the most highly contaminated sediments may have been able to be managed on land.
Radioactive substances and dioxins may be contained within the toxic sediments.  However there is NO data on these important toxins. This omission is in breach of NODG guidelines (National Ocean Disposal Guidelines for Dredged Material [2002]) 

The Trial Dredge did not include any examination of the toxic sediments.  Therefore there is no reliable data on which to base an assessment of water quality.  Nor was sediment grain-size adequately factored in to water quality monitoring.  Finer particles are the most highly contaminated, take longest to settle and travel the furthest.  This fact ought to have been built into water quality modelling.  It was not. 

Toxic plume mapping shows a toxic plume extending kilometres away from the dredging site.  It does not appear to have taken sufficient account of the currents in the Bay or the possibility of storm surges moving the plume. It is possible that the toxic plume may land on Melbourne’s premier tourist beaches.  It also has the potential to affect the St Kilda penguin colony and Ricketts Point Marine Sanctuary. 

There are serious questions as to whether or not the containment strategy will work.  It will be months, possibly longer, before the toxic sediments can be capped.  There are serious questions as to whether the toxins will be contained by the bund.  The bund has a design life of 30 years. Toxins are expected to last much longer; some are intractable.   

The risk to recreational swimmers was classified as “minor” in the Human Health Risk Analysis (HHRA, Appendix 60).  “Minor” includes up to 100 people becoming ill and up to 10 developing a major illness, such as cancer.  This risk to recreational swimmers was not acknowledged in the main SEES report, nor were any mitigation strategies put in place. 

The Human Health Risk Analysis (HHRA Appendix 60) did not find any unacceptable risks in relation to people eating fish.  However the HHRA cannot be relied upon as it was too narrow in its scope, included too many false assumptions, used less than rigorous screening tools and concluded with too great a level of uncertainty.  In line with the rest of the SEES, it left out analysis of important issues, in this case any examination of dioxins or radioactivity within the toxic sediments.  It ruled out any examination of shellfish or eels on an assumption that these species were not eaten, or only eaten in small amounts. This is not true.  In the case of shellfish, the assumption appeared to be that if taken illegally, any resultant poisoning was of no concern to the PoMC. 

The HHRA ruled out the potential for many of the heavy metals to pose a risk to public health on the assumption that they do not bio-accumulate.  This assumption has also proven to be untrue.  It used screening tools that have been shown to be less rigorous than those used by the EPA.  The levels of uncertainty within the analysis left sensitive subpopulations at risk.  The authors concluded with an acknowledgement of large degrees of uncertainty and a recommendation for further research.  Research that to our knowledge has not been done.

Toxic algal blooms remain a serious public health, economic and environmental risk. The risk of toxic algal blooms ought to have been minimised through “best practice” project design.  This has not occurred. 

The toxic load on the Port Phillip Bay environment is huge and possibly unprecedented.  There is the potential for significant local and Bay wide environmental impacts.  The potential impact of toxic algal blooms on the St Kilda penguin colony has been seriously under-estimated.  This is one of many environmental impacts of toxins that have been under-estimated in the SEES report. 

The Independent Panel’s 2005 recommendations in relation to crucial Northern Bay and toxicant issues have not been complied with. On that basis alone, the project should not proceed.

Classification and Management of sediments


At least 2.6 million tonnes of dredge material is toxic.  It is so toxic that it has been classified as unsafe for “unconfined marine disposal”.  Toxic hotspots were identified as The Docks area, the Yarra River (both North and South), The Batter Wall and The Williamstown Channel.  There were also five areas of deeper, clay sediments that were contaminated with DDT and dieldrin which were also classified as unsuitable for unconfined disposal.

The unconsolidated silt from the Port Melbourne Channel has been classified as acceptable for unconfined disposal, however Irvine states: “this conclusion is not supported by the toxicity and 95% UCL data and cannot be accepted on the basis of the evidence presented”1

Concentration of toxins

Concentrations of toxins in the sediment warrant further attention.  The levels of Polycyclic Aromatic Hydrocarbons (PAHs) were found in concentrations of 9872 microg/kg- 10,000 times acceptable screening levels.  Dieldrin was found in concentrations 22,000 times the acceptable screening levels. Arsenic levels were 66 times the screening levels.   DDT was present in concentrations of 555 microg/kg-17 times the screening values.

Mix of toxins

A great mix of toxins is present in the sediments.  Whilst there was some analysis of the effects of combined toxicity, this analysis did not appear to be carried through to sediment classification or disposal management plans.  This is particularly the case for the Port of Melbourne Channel.  This is a serious omission.  In human health literature it is increasingly recognised that illness often occurs as a result of multiple drug toxicity rather than the effect of a single agent alone.  Similarly Irvine2 writes of the importance of “additive or synergistic effects of the low levels of contaminants present that are causing toxicity”. 

Overall toxic load

The toxic load on an ecosystem relates to the absolute mass of toxins.  This is calculated by multiplying the concentration of toxins by the volume of toxic sediment.  The proposal involves a unique situation - an extraordinarily large volume of sediment that has exceedingly high concentrations of toxins contained within it.  This gives us an extraordinarily large and possibly unprecedented quantity of toxins being released into the Port Phillip Bay environment. 

We know that this project is massive on a world scale-more than twice the size of any other dredging project world-wide (EES panel report p113).  Can the POMC tell us of any other dredging project that has involved the disturbance of such a great quantity of toxins?  If so, can they tell us of the environmental impacts?  Has the overall toxic load been quantified?  Have the potential environmental impacts of this quantity of toxins been properly evaluated?  If so where are these figures within the SEES?  What analysis has been done of the potential environmental impacts of releasing this quantity of toxins into the Port Phillip Bay environment? 

The risks involved with releasing this quantity of toxins into the environment are just not worth it.  On this basis alone, the project ought not to proceed. 

Sampling of sediments

Sampling of underlying sediments has been inadequate, due to the assumption that they were uncontaminated.

There are many contradictions between the resource documents. This was particularly the case in relation to the contamination status of sediments.  One states, “regarding underlying consolidated sediments, that two areas in which DDT concentrations exceed NODG Screening Levels or dieldrin concentrations exceed the LOR (which is greater than the screening level) were defined in the docks”. (Appendix 36 Final Report, Northern Channel Sediment Investigation Executive Summary (CD version) p.5).
And “significant organic contamination of sediments within the mouth of the Yarra River, extending well below the surface sediments, has been previously reported from lubricating oils and PAHs’ (Appendix 36 Final Report, Northern Channel Sediment Investigation, section 3-5).
Yet in another document: ‘Stiff clays (comprising Coode Island Silts and Fisherman’s Bend Silts) underlying the soft sediments are assumed to be uncontaminated by anthropogenic sources (including groundwater discharge)…’ (Appendix 36A Sampling and analysis plan (SAP) CDP Northern Channels Sediment Investigation URS 9 August 2006, section 2-23).

It is the  apparently unjustified assumption that underlying sediments are uncontaminated, which led to inadequate sampling of underlying sediments, especially sediments below 0.5m, in the most recent studies for the proposed channel deepening project.

Lack of adequate sampling means that the proponent has failed to adequately characterise the sediments proposed for dredging, leading potentially to a serious underestimate of the amount of contaminated material that has to be placed in confined ocean disposal or disposed of to land after treatment.

Sampling method

Samples were collected using a grid pattern that appeared to miss the middle of the Channel, and very little sampling was done to the full depth of proposed dredging.  This sampling pattern is neither random, nor is it targeted. 

No attempt was made to locate hotspots in any of the channels by reference to historical incident reports, or known point sources of contamination, past and present, and to target those locations for sampling.

The grid pattern is a clearly inadequate sampling strategy.  A combination of targeted sampling based on historic incident reports, combined with the well accepted method of random sampling ought to have been used.  In the absence of proper sampling, one can only assume that the toxicity of the sediments has been underestimated. 

Unclear and inadequate sample size

It is not clear how many samples were taken. One document states that stiff clays underlying the soft sediments would be tested at 10 locations in regular intervals using, to the full depth of proposed dredging, a vibrocorer3. Another document states: “Vibrocoring in the Northern Channels was undertaken at 26 locations to test the consolidated sediment to a maximum depth of proposed dredging or the limit of coring capacity”4

A search for further clarification might lead you to ‘Appendix B Borelogs’ at the rear of Appendix 36 Final Report (Hard Copy), but that page states that Appendix B is only provided electronically. The following requires further investigation:

  1. How many locations were sampled to the proposed depth of dredging?
  2. The sedimentary deposits of the Yarra River delta are complex, and we are not satisfied that the soft sediments are uniformly underlain, to the full depth of proposed dredging, by stiff clays, or are not underlain with clays heavily contaminated with toxins.
  3. The sediments below the unconsolidated strata should have been sampled more thoroughly to the full depth of proposed dredging.
Toxicity data has been used despite that data being found to be invalid

In Irvine’s recommendation 43, there was an issue with validity of previously collected data.  Irvine says:  “A key assumption determining the scope (NC Report Section 1.3) was that previously collected data would be validated and, where deemed suitable for the purpose of the sediment quality assessment, used along with the data to be collected in the 2006 study to comply with the minimum number of sampling locations required, as per the NODG.

The data validation in Appendix L (Technical Appendix 36) concluded that the previous toxicity data was inadequate to assess whether the dredged sediment was suitable for unconfined disposal, and this data was not used in the NC assessment.

The data validation identified a number of inadequacies in the sediment analytical data collected prior to 2006, i.e., ‘the majority of the data reviewed did not comply in one or more aspects of quality control requirements specified by the data validation documents used.’”5

The report concluded that, therefore, the pre-2006 data was only suitable for limited interpretive use, ‘such as development of a supplementary sediment sampling program’ 6

Despite the clear inadequacies of the pre-2006 data, it has been used in the overall Northern Channel investigation, further damaging the credibility of the investigation.

Toxic Sediments have not been categorised into moderately or highly contaminated sediments

The failure by the proponent to categorise the toxic sediments in adequate detail has made the separation and treatment of the most dangerous parts of the sediments very problematic

Hence, while being able to identify the volumes of contaminated material in Appendix 237 we cannot know how much of the 3.9 million m3 of contaminated material is actually highly contaminated, and should be treated on land.

The SEES concludes that since the volume of contaminated material is too large to handle on the Port land near Webb Dock, then it must all be sent for disposal in the DMG. If it was known just how much of the contaminated material is highly contaminated, then that portion could be treated on land and the less contaminated material sent to the DMG. This option appears not to have been considered. 

EES Panel Recommendations –have they been followed?

The Independent Panel recommended against allowing the project to proceed in 2005.  One of the Panel’s chief concerns was the environmental risk associated with the toxicity of the Northern sediments.  The Panel gave a number of recommendations as to what further action needed to be carried out.  These recommendations have not been properly followed:

Sampling design needs to be targeted, based on historical data

EES Recommendation 29 states:

“It is essential to carry out historical research to disclose locations of potential contamination in the Yarra sediments, to guide the selection of contaminants to be investigated, sampling design and the location of potential ‘hotspots’.”

EES Recommendation 31 states:

“The proponent should design a new sampling strategy for the Yarra zones. The historical use analysis and the silt distribution map recommended above should be used, together with the results of a critical review of previous studies. This is required to ensure that the results obtained are representative of the material to be dredged, in both area and depth. NODG provides clear guidance on this process, which should be followed. The number of samples should be sufficient to yield statistically valid results that as a minimum meet NODG requirements. The sampling strategy should be documented and externally approved before additional survey work commence.”

EES recommendation 35 states:

“The results of whole of sediment toxicity testing to date show the Yarra sediment to be acutely toxic, leading to an NODG classification of ‘highly contaminated’. This eliminates the option of open marine disposal for most of this sediment and necessitates development of more expensive and complex management solutions. For this reason, it is important that the Yarra sediments should be examined in more detail, to determine the distribution of the toxic material and contamination hotspots. A more comprehensive, flexible and targeted sampling strategy should inform the development of a wider choice of disposal methods.”

The SEES documents give a general overview of historical contamination.  However they do not discuss historical incident reports.  Nor does the SEES design a targeted sampling strategy to account for these potential hotspots.  We could expect that old factories, drains, spills from ships or wharves, discharges from refineries, and wharf wash-down points etc. may have created hot spots of toxins in the Yarra Channel and banks. Spills of toxins from ships or barges, sinking of boats with toxic cargoes, or legal and illegal dumping of toxic substances may have occurred along any of the ship channels in the north or south of the bay. The EPA has a register of incident reports, and has also licensed discharges from industry since 1970, but these sources of information have not apparently been referred to.

Other older sources of information, e.g. Victorian Channels Authority, Ports and Harbours branch of the Public Works Department, or Melbourne Harbour Trust (established in 1887) have not been referred to either. Many of the records of the Harbour Trust are in the State Library.

Point sources of contamination, as indicated by historical documents ought to have been targeted for sampling as per recommendations 29 and 31.  The sampling strategy used was a grid pattern, this is in now way “flexible or targeted”.  Therefore Recommendations 29 and 31 and particularly Recommendation 35 have not been followed. 

No detailed categorisation of the toxic sediments has been done.

EES recommendation 36 states:

 “Using better information, the disposal strategy should be re-examined with a view to considering separate disposal methods for highly contaminated, moderately contaminated and uncontaminated materials. Different approaches to work scheduling and disposal scheduling should be considered”.

The SEES fails to discriminate sufficiently between highly contaminated, moderately contaminated, and materials with low contamination, the claim being that this is too difficult. This avoids the potential expense of land based treatment and disposal of the most toxic materials.

The SEES reports that areas of sediment with higher contaminant concentrations were identified throughout the entire Northern Channels using the Combined Dataset8. The number of contaminants exceeding NODG Maximum Levels at each location is shown in Figure 80. The majority of samples in which Maximum Levels were exceeded are located in the Batter Walls (15 samples), Docks (8 samples), and Yarra North (13 samples and in other places).

Nevertheless, the material from the Batter Walls, Docks and Yarra North could be allocated to land based treatment and disposal, along with material from other hotspots, although the volume of material involved appears to be more than the proponent wants to contemplate for land-based disposal.  It is clear therefore that Recommendation 36 has not been followed.

Land based options must be explored, according to panel

EES recommendation 39 states:
“The failure of the EES to significantly evaluate land disposal options is a breach of policy. Options for disposal to land, particularly for contaminated spoil from the north, should be fully evaluated and assessed, with reference to the international literature, including the practice of land-based treatment and re-use of materials including contaminated materials at De Slutter, Port of Rotterdam, The Netherlands. ”
The SEES fails to adequately address the issues of land-based disposal. As mentioned above the sub-classification of toxic materials was not done. Technologies for dewatering toxic materials were not mentioned. Some current dewatering technology employs mineral ore concentrators, centrifuges, or large textile based filters or polymer flocculant/congealant based machinery. Toxic spoil does not have to be left in large piles in a dump until the water drains out of it by gravity.
Toxic spoil that is dewatered and treated to remove toxicants may have a market value. It would not necessarily have to be disposed to landfill. Microbial leaching can be used to remove heavy metals, and steam treatment using microwave-heating techniques can be used to remove volatile and semi-volatile organic compounds (including PCBs) from the moist material.
Singapore and other Asian states are buying sediments mined from the ocean floor for use as fill and for construction purposes. Marine derived sand is used in Asia for making concrete and cement blocks. It is quite clear that recommendation 39 has not been adhered to.

Best practice approach to dredging has not been followed

EES recommendation 101:

 “A best practice approach to dredging should be pursued, as it will provide significant opportunities to reduce or better control the likely impacts on the commercial fishing and Abalone industries. The detailed impact of the project on these industries cannot be assessed until relevant changes to the means of implementation are known and assessed.”

Best practice has not been pursued. The cheapest options have been favoured. Use of new sub-surface "keyhole" dredging technology from Boskalis BV is now available for full-scale commercial applications, following successful trials in the Netherlands, but has not been considered in the SEES.

A best practice approach in relation to the reduction of the risk of toxic algal blooms has not been pursued.  Dredging has been scheduled to occur at a time when toxic algal blooms are most likely, quite the opposite of best practice.  Recommendation 101 therefore has not been adhered to.

Key recommendations of the EES panel have not been followed.  On this basis alone the project ought not to proceed.

Radionuclides not examined - Breach of NODG

The sediments ought to have been assessed for radioactivity.  No assessment has been made. We should therefore conclude that the sediments or parts thereof may be radioactive and ought not to be disturbed, until this matter has been properly investigated.

According to the POMC “A decision was made to omit an assessment of radionuclides”. It then refers to a report done by the EPA “five years ago”

Irvine notes9: “Given that parts of the Northern Channel area contain a wide variety of industrial contaminants, and therefore could contain radionuclides, reliance on previous studies would only be acceptable if the data was from the areas proposed for dredging and the data was current (as defined in NODG).”…. The NODG states that radionuclides “need be done only once for any particular dredge area however there is no latitude for omitting them completely”. The proponent has chosen to omit them completely.

Irvine continues:” The report in Appendix K was actually written in 1996 based on two samples collected from the bay the previous year, one from the mid-bay and the other from the northern bay, somewhat west of the Port Melbourne Channel, and therefore cannot be considered to be within any of the current dredge areas. The study only investigated recently formed radionuclides (Beryllium-7, Lead-210, Radium-226 and Caesium-137), as its purpose was to determine sedimentation rates in the bay. It did not determine total radioactivity or radioactivity from longer-lived elements which occur naturally in sediments or from industrial pollution sources”

“On this basis, the proposal is not compliant with NODG”

Important toxins ignored

According to the POMC “a decision was made to omit an assessment of dioxins/furans”

Dioxins have already been responsible for the recent ban of commercial fishing in Sydney Harbour and associated demise of the fishing industry. The term dioxin is applied to a group of chemicals that have been considered by the World Health Organisation (WHO) to be of toxicological concern.  Dioxins ought to have been given particular attention in the SEES report.  In fact there is NO data on dioxins as no assessment has been done.

Unlike the EPA Fish Study10 dioxins (PCDD), furans (PCDF), and brominated diphenyl ethers (PBDEs) were not tested. Polybrominated diphenyl ethers (PBDEs) (flame retardants) have recently been added to the US EPA target list as an emergent issue and were added to the analyte list. The EPA found that while PCBs may not be particularly high in finned fish, they could reach high levels in eels and other species. They are known to accumulate in shellfish and other benthic organisms, especially in fatty tissues.

The term dioxin is generally applied to a complex group of polychlorinated dibenzo dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Of the 210 known dioxins a group of 17 PCDDs and PCDFs are considered by the WHO to be of toxicological concern. In addition to this group are 12 dioxin-like PCBs, which display dioxin-like toxicity.

PCDDs and PCDFs are not produced deliberately; they are formed as a by-product of chemical and combustion processes. These range from natural events such as bush fires to man made processes such as the manufacturing of chemicals, pesticides, steel and paints, pulp and paper bleaching, exhaust emissions and incineration.

The SEES ignored these compounds because they are only present in very low concentrations in the waters and sediments of the Bay.  However the levels needed to cause problems are also exceedingly low.  The Action Level endorsed for the NSW Authority of 6 pg TEQ/g fresh weight can be used as an appropriate reference point to guide the assessment of dioxin concentrations in fish in this investigation, given it has been derived locally for a similar purpose.  The EPA report found that only one fish sample exceeded the NSW Action Level, but all samples contained some of these compounds. If the toxic sediments in the port area of the Yarra were disturbed by dredging, then it is quite likely that biota coming into contact with these sediments will become contaminated.  Note that there is no published safe value for the PBDEs.

Since all of these compounds are extremely toxic, they should have been tested in the SEES studies.

Water Quality

No trial dredging was done of the toxic sediments therefore we have no reliable data.

There is a great deal of weight given throughout the report to Water Quality data in relation to the risks of toxins on the marine ecosystem and on Public Health.  The possible flow-on effects of toxicants was not considered by many of the consultants, as they were informed that, based on the data available, water quality would not be significantly affected by the Channel Deepening Project. 
The trial dredging did not involve the Yarra or any of the contaminated sediments.  We therefore have NO reliable data on which to base any conclusions about water quality following dredging of the toxic sediments. 

The Authors of the CDP Human Health Risk Assessment (Appendix 60) relied on Jennifer Hale’s SEES Trial Dredge Technical report (X1.1). Hale (2006) summarised the results of water quality monitoring conducted as part of minor maintenance dredging using a backhoe dredge.  There are a number of questions that must be raised about the relevance of this report:
  • Are the sites that were dredged comparable?
  • The site is “The Port of Melbourne”; does it include toxic hot spots? 
  • Do they have the same toxins within them and the same silt characteristics? 
  • Is the method of dredging comparable? 
  • Is the plume comparable?
As this report is not available for public scrutiny (see section on risks to recreational swimmers), the answers to these questions cannot be found.  It is clear however that the method of dredging is in no way comparable. 

The authors of Technical Appendix 60 were advised by email that “the small amount of material being put into suspension by a backhoe or bucket dredge in unlikely to cause a plume which would impact significantly on the environment.  Further: “During maintenance dredging using a backhoe, a turbid plume was not measurable more than 100m away from the dredge; this is comparable to a plume from a TSHD which can disperse several kilometres from the dredge”11.  One can conclude therefore that the modelling used in Hales report is in no way comparable to what we can expect from a TSHD. 

Sediment grain size not properly factored into modelling

The smaller the grain size, the greater the degree of contaminants that are bound to them. How contaminants bind to particles is very dependant on surface area- see Fig 67 and 68 in the North Channel Toxicant report.  The smaller the grain size, the longer the sediments stay suspended in the water column and the further they will travel.

Contaminants are adsorbed onto the surface of the particles, so the amount adsorbed for a given mass of material is proportional to the total available surface area, which is in inverse proportion to particle diameter. The settling velocity of the particles follows Stokes Law, which says that the settling velocity of small particles is proportional to the square of the particle diameter. Hence, a halving of the diameter means that the velocity will be a quarter as much. The particles will settle much more slowly. Therefore, very small particles will be carried a lot further in the currents than larger particles.  So the finest sediments are likely to be the most highly contaminated, stay in the water column the longest time and travel the furthest.  This does not appear to have been properly addressed in the water quality modelling, or if it has it is not readily available to the public.

Toxic plume may land on inner city beaches

The SEES presents evidence that released toxicants may reach inner city beaches, including the Jawbone Marine Sanctuary in Williamstown. See data following:

  1. Contaminated Plume Map from SEES Chapter 10 Page 72
  2. Williamstown Channel dredging model. Figure 8 Appendix 1 of Appendix 43
  3. Wind driven current Map SEES Main Report Chapter 8 figure 8.8
  4. Storm event plume from Yarra reaching Ricketts Point
  5. Contaminated and “non-contaminated” sediment that is reaching Melbourne Beaches. Figure 43 and 44 of Appendix 43:
Contaminated Plume Map SEES Chapter 10

Williamstown Channel dredging model. Figure 8 Appendix 1 of Appendix 43

Theses plume models demonstrate that there will be a large toxic plume extending out many kilometres from the dredging operations.

In other parts of the SEES and in the Port Phillip Bay Environmental Study 1996 the clockwise flow of currents around the Bay is acknowledged.  It is also acknowledged that these currents move water from around the Yarra and Docks area down around the Eastern shores of the Bay past inner City beaches12 Storm events are well known to carry water from the Yarra and Docks area many kilometres down the Eastern shores of the Bay, down to Ricketts Point

Wind driven current Map SEES Main Report Chapter 8

Figure 8-8 Depth averaged wind driven currents: summer map

Storm plume bringing Yarra water down the East Coast to Ricketts Point.  Port Phillip Bay flood plume (November 1993) CSIRO

Contaminated and non-contaminated sediment reaching Melbourne beaches.  Figure 43 and 44 of Appendix 43
These currents and the possible impact of storm events appear to have been neglected in the modelling of the toxic plume.

The URS Risk Assessment includes Appendix C, Risk Register, in which a table lists issues specifically excluded from SEES Risk Assessment.

Modelling inaccurate” is listed as an “excluded issue”. The “Reason for exclusion” being “Modelling uncertainty accounted for through conservative risk assessment approach and expert interpretation.

The Risk Register also notes, “heavy rains compounding the effects of turbidity” as an “excluded issue”, the reason being “Modelling uncertainty accounted for through conservative risk assessment approach and expert interpretation.

Further, flawed turbidity modelling has resulted in the area to be affected by plumes in the north of the Bay to be understated. 

The fact that these issues have been inadequately assessed has lead to their not being adequately
addressed in the Human Health Risk Assessment report.
We note that the “non-contaminated” sediments in the Port Melbourne Channels may well be contaminated13.  The largest plume maps generally relate to the “non-contaminated sediment plumes.  According to Irvine these may well be contaminated, leading to a serious under-estimation of the extent of the toxic plume and associated health effects. 

Risks include but not necessarily restricted to:
  • Contaminated sediments extending to include Melbourne’s premier Inner City Beaches.
  • A toxic plume could land on Melbourne Inner City Beaches including beaches from Port Melbourne to Ricketts Point. 
  • Serious adverse effects on the St Kilda penguin colony and the Ricketts Point and Jawbone Marine Sanctuary are possible 
  • Mobilisation of contaminants and toxicants also has the potential to have a serious public health implications and serious implications for tourism around the Northern Inner City beaches. 
  • Dredging of the Northern Channel is planned to occur over the summer months, starting January 2008.  It is possible that Inner City Beaches will need to be unsafe for swimming as a direct result of the Channel Deepening project.

 [1] Irvine p50, Appendix 37
 [2] Recommendation 55, Appendix 37
 [3] SEES Appendix 36 A - CD version, Sampling and Analysis Plan, Selection of Sampling Locations, Sect 4-3
 [4] Appendix 36 Final Report (Hard Copy), North Channel Sediment Investigation, section 4.2.2
 [5] Appendix L Page.4, paragraph 2
 [6] Appendix L Page 5 & 6.
 [7] Tables 1 & 6 Appendix 23
 [8] Appendix 36 Final Report, Northern Channels Sediment Investigation (Hard Copy), section 6.5.4
 [9] Irvine Appendix 37, Recommendation 23
 [10] Yarra and Maribyrnong estuaries: Investigation of contaminants in fish, EPA Technical Report, January 2007
 [11] SEES Technical Appendix 60 Page 48
 [12] SEES Main report Chapter 8 Section 4.5
 [13] Irvine December 2006 Report Page 50

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