The Mandurah Estuary Bridge Duplication project involved the replacement of the existing timber bridge structure on Pinjarra Road near the Mandurah CBD in Western Australia. To accommodate the new bridge structure, BG&E was engaged to relocate the water distribution main from the existing timber bridge.

The project included detailed design for two stages to suit the new bridge construction:

Stage 1

Consisting of 200 metres of DN450 PE water distribution main, including valving and installing a magnetic flow meter in a permanent bespoke underground concrete enclosure.

Stage 2

Consisting of 250 metres of twin DN630 PE water distribution mains, horizontally directional drilled at depth under the Mandurah estuary seabed. Stage 2 required complex valving and bypass arrangements on each side of the estuary crossing to enable the Water Corporation to switch between the two pipe lines for future redundancy should a pipe failure occur under the seabed.

The project was completed in 2018.