Sonar search for Dulcie's body

A RAN officer with the side-scan sonar equipment used to search Green Lakes for Dulcie Birt’s body. Photos: Rob Williams MA0910WI

ROYAL Australian Navy searchers are using sonar equipment in an effort to pinpoint the location of Dulcie Birt’s remains.

The Navy’s Mine Warfare Geospatial Deployable Systems Team joined police in the operation at Green Lakes, near Riverview, on Tuesday morning.

A long, cylindrical, remote controlled device will be manoeuvred around the water, taking pictures of the bottom, which will then be sent to a computer observation area on the banks of the lake.

Members of the Navy team will then analyse the images closely, looking for any signs of human remains.

Police divers have already spent several weeks conducting fruitless underwater searches of the abandoned coal mine, which is now 32m deep at its deepest point.

The dark depths are home to countless dumped cars, dead trees and various junk which have made previous searches dangerous.

Although it hampered efforts in the past, the poor underwater visibility should not stand in the way of the Navy’s equipment.

Officer in charge of the Navy search team, Lieutenant Commander David Ince, said a full search of the lake should only take one day to complete.

“Our piece of equipment is very good at finding quite small pieces of clutter, although this dam is a very different operating area to what we would have worked in previously,” Lieutenant Commander Ince said.

“It’s basically called a side-scan sonar; it works in the 900 to 1800 kilohertz range, and with that we can get centimetre resolution. It’s a commercial piece of equipment but it has got very high definition, high-frequency sonar.

“I’m never going to say we’re confident of finding what we are looking for – I don’t want any expectations – but I will say that this equipment is very good at finding small objects and we’re hopeful of a successful outcome.”

Police divers are on standby in case the Navy search does uncover something that is worth recovering from the dam.

“The purpose of the search is to repatriate the body of Dulcie Birt back to her family,” Det Insp Mick Niland said.

Police are also keen to find the missing side tray from a Mitsubishi Triton utility that was seized at the beginning of the investigation into Dulcie’s disappearance – in October last year.