507 Murray Street, Perth

507 Murray Street, Perth

A very tough engineering challenge. This narrow site had neighbouring properties built to the boundaries on three sides and required a deep basement for an electrical transformer. One neighbour was a heritage-listed building in a very dilapidated state, which also affected the construction methodology.

Budget constraints called for some out-of-the-box thinking, because grout injection for the basement and footing excavations would have put the project over budget.

A concrete caisson was used for the basement. The basement walls were cast at ground level and an excavator was lifted inside. As the excavator dug down, the walls sank into the ground without the need for any temporary retention. This may have been the first time the method was used in Perth, and it saved the client hundreds of thousands of dollars.