Barge to Drill Core Samples

A barge-mounted drill rig will collect core samples in the north and south Tar Ponds over the next six to eight weeks.

Thirty-nine core samples will give design engineers a more detailed understanding of the physical properties of the bedrock under channels to be built through the Tar Ponds this summer.

Previous sampling programs concentrated on the environmental properties of sediments throughout the Tar Ponds. This program focuses on a specific route, and will concentrate on bedrock.

Earth Tech and CBCL, the engineering firms carrying out the final design of the cleanup, will supervise the work. Project manager Joe Sullivan said the drilling will provide crucial information about the geology of the bedrock that will anchor the walls of the channels. The barge will drill 1.6 metres into the bedrock.

"We need to know the depth at which bedrock starts, and such things as whether it is solid or fractured," Sullivan said. "That information will influence the final design of the sheet pile wall."

The channels will provide a clean corridor for water from Coke Ovens Brook and Wash Brook to flow through the Tar Ponds to Sydney Harbour.

The main channel will stretch 2.5 kilometres from the end of Wash Brook at Prince Street, to the gap in the newly built Battery Point barrier. The western shoreline of the Tar Ponds will form one side of the channel. The eastern side of the channel will be built using interlocking steel sheet pile.

A shorter branch channel will connect the main channel with Coke Ovens Brook, on the east side of the south pond. All the channels will be designed to have a natural appearance.

Maritime Testing Ltd. and Boart Longyear Inc. will carry out the core sampling program.