People walking along the Yarra riverbank in Melbourne's CBD over the last few months may have noticed divers hauling mangled shopping trolleys, barnacle-encrusted bikes and large bits of sodden timber onto pontoons.
The divers are contractors giving the river a deep clean as part of Parks Victoria's four-year Maintenance Dredging Program.
The debris they gather can range from large bits of wood to expensive bikes – perhaps stolen from their rightful owners – scooters, shopping trolleys, tables and chairs.
Dredging removes sediment and silt that clogs up the river and can make it harder for boats to navigate. This program has the added benefit of removing large debris that might not have been noticed before.
Parks Victoria has litter traps on the river which catch smaller debris and rubbish and rangers remove any large debris found floating in the river but dredging allows for a deeper clean.
"Dredging removes the things we can't see, that might not be revealed by low tide," says Dr Haya Daghlas, Parks Victoria's Waterways District Manager.
A typical collection of debris from one of the dredging sites along the Yarra. Photo: Australasian Maritime Associates.
This year, divers have removed more than 60 bikes, more than 40 trolleys and at least a dozen tables and chairs.
"We need to work together to make sure this debris doesn't end up in the river and we keep the Yarra open, safe and clean for us all to enjoy," Dr Daghlas says.
Once the debris is out of the way, the dredge, operated by contractors Australasian Maritime Associates, can go in and get to work.
By November the dredge will have removed more than 20,000 cubic metres of silt – eight full-sized Olympic swimming pools – deepening the key navigation channels and landings from Dights Falls to the Docklands by up to a metre and a half.
A deeply-buried bike emerges from the silt and sediment during a dredging operation. Photo: Australasian Maritime Associates
