Just when you’re told the dredging is over… a further 300,000 m3 of ‘contaminated and uncontaminated’ Yarra sediments are to be dredged and dumped in the Bay in the so-called ‘Confined Aquatic Disposal Area’ (CAD). But how do we know the toxins will be confined?
The CDP Environmental Monitoring Plan (EMP) admits that “contaminated unconsolidated sediments will require dredging and disposal prior to completing the bund” (see page 64). But the EMP doesn’t require any testing for toxins in the seabed in or around the CAD.
Grab dredge fills barge with Yarra silts
For the CDP, the ‘larger’ Trailing Suction Hopper Dredges used a ‘diffuser arm’ to place contaminated sediments close to the seabed, where they would be less likely to be dispersed by marine currents. But barges filled by ‘small’ back-hoe grab dredges dumped around 400,000m3 of silts through the whole water column, to be more likely spread by wind-driven waves. On reading the requirements for Containment of Contaminated Material detailed in the EMP (p. 64), there seem to be no plans to check if toxins were successfully contained.
