Decades of research show contaminants

The EIS lists contaminants as “Potential” but their presence is well documented.

Risks to human and environmental health due to disturbance of contaminated toxic sediments

The EIS fails the Secretary’s Environmental Assessment Requirements (SEARS) due to inadequate assessment of the risks to human and environmental health due to disturbance of contaminated toxic sediments. The EIS scope ignored detailed scientific knowledge key to informing the public, including the toxicity of sediments in WHT proposed area. The contaminants were listed in Appendix M on pages 56 and 57 in Tables 4.2 and 5.2 as “Potential” contaminants. This is misleading because the cocktail of persistent contaminants and their concentrations are well documented.

This weight of evidence from decades of research shows that Sydney Harbour sediments are among the most toxic globally. Quantification of the contaminant mixture includes a suite of metals (Birch et al. 2017) and non-metallic contaminants including organochlorine pesticides (OCs, Birch and Taylor 2000), polycyclic aromatic hydrocarbons (PAHs, McCready et al. 2000), dioxins and furans (Birch et al. 2007), polybrominated ethers (PBDEs) and the highly toxic biocide antifoulant chemical tributyltin (MEMA, 2014). It is the mixture of these chemicals and the sediment pore water interface that creates toxicity to marine life (McCready et al. 2006: Birch et al. 2008). These chemicals also have severe impacts on human health as carcinogens. The Proponents did not include this wealth of data in the scope of Appendix M and there is no mention of sediment pore water as a source of toxicity. One can only surmise that they chose not to use this information

The release of a toxic cocktail of contaminants through dredging is of great concern especially with respect to the chemical mixtures and the additional risk of disturbance of acid sulphate soils. Acid sulphate soil/sediment (ASS) leachate releases sulphuric acid into the environment, reducing seawater pH and thereby increasing the bioavailability of metals and other contaminants, making matters even worse. The combination of ASS and chemical mixtures in sediment and pore water presents a very high risk to marine life. This was not considered in the EIS.

Major pollution and environment impacts such as fish kills, and human exposure seem inevitable. Shallow silt curtains are considered, but these will not prevent movement of contaminated fine particles. Full-length curtains anchored to the seafloor are the only viable method of control. No curtains can prevent dispersal of sediment pore water.

In accordance with the SEARS, no decision to excavate sediments can be made until the data on the concentration of the contaminants are provided, the toxicity determined, the volumes of contaminated sediment to be excavated documented and the requirement that this be addressed as a remediation project assessed.

Dr. Maria Byrne, 24 Grove St Birchgrove

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References

• Birch et al., (2007) The source and distribution of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofurans in sediments of Port Jackson, Australia Mar Poll Bull 54: 295-308.
• Birch et al., (2008) Contaminant chemistry and toxicity of sediments in Sydney Harbour, Australia: spatial extent and chemistry-toxicity relationships. Mar Ecol Prog Ser 363: 71-87;
• Birch & Taylor (2000) Distribution and possible sources of organochlorin residues in sediments of a large urban estuary, Port Jackson, Sydney. Aust J Earth Sci 47: 749-756
• Birch & Taylor (2002) Application of sediment quality guidelines in the assessment and management of contaminated surficial sediments in Port Jackson (Sydney Harbour), Australia. Env Mgt 29:660-670. Birch (2017) Assessment of human-induced change and biological risk posed by contaminants in estuarine/harbour sediments: Sydney Harbour/estuary (Australia). Mar Poll Bull 116:234-248.
• Birch & Lee (2018) Baseline physico-chemical characteristics of Sydney estuary water under quiescent conditions. Mar Poll Bull 137: 370-381
• Drage et al. (2015) Historical trends of PBDEs and HBCDs in sediment cores from Sydney estuary, Australia. Sci Tot Env 512-513: 177-184
• McCready et al, (2000) The distribution of polycyclic aromatic hydrocarbons in surficial sediments of Sydney Harbour, Australia. Mar Poll Bull 40: 999-1006;
• McCready et al, (2006) Relationship between toxicity and concentrations of chemical contaminants in sediments from Sydney Harbour, Australia, and vicinity. Env Mon Ass 120: 187-220.
• MEMA Sydney Harbour Background Report (2014) Sydney Institute of Marine Science prepared for NSW Department of Primary Industries