‘Im outraged’: Secrecy over plan to dig up Sydney Harbour’s toxic sludge

contamination clean up efforts at Homebush and Barangaroo, has now decided to speak out, slamming the decision to withhold the ‘‘critical’’ report.

‘‘I’m outraged,’’ said Ryall, who lives near the project area at Birchgrove. ‘‘Without it I can’t assess the risk to human health or the marine environment’’.

The slew of dangerous toxins have built up on the harbour floor over more than 150 years of industrial activity and storm water overflows flushing pollutants into the harbour.

Past studies have shown the tracts of sediment are among the most contaminated in the world – worse than Tokyo Bay or New York Harbour.

The chemicals include dioxins – carcinogens that can cause birth defects – along with hydrocarbons, tributylin, polychlorinated biphenyls, pesticides, heavy metals and per- and polyfluoroalkyl chemicals (PFAS).

Ryall fears the plans may not adequately protect the public and the environment, including fishermen and families who swim in harbour pools across the foreshore.

Transport for NSW released the draft plans in January, which will see the construction of twin tunnels linking Rozelle with the Warringah Freeway in North Sydney.

The harbour would be crossed using two pre-fabricated tube tunnels, lowered onto the sea floor between Birchgrove and Waverton.

Trenches would secure the tunnels in place, meaning workers would have to dig up a heavily polluted layer of sediment 1.5 metres deep.

– Nine