CHALLENGE

Waterhen is the Royal Australian Navy’s lead establishment for Mine Warfare nestled in the Northern side of Sydney Harbour. A shore establishment occupied by the crews of the RAN’s advanced Mine Countermeasure vessels and their support services, all contributing to the RAN’s mission. This complex maritime project was to repair the 600m seawall clad in sandstone that runs the length of the naval base’s sea-facing gateway. The wall was showing signs of decay that demanded structural upgrades and lighting replacement for the existing recessed light fittings, having reached their end of life. The main challenges were the site’s foreshore location and to deliver the project in four months without disrupting activities of this large, active naval base.

SOLUTION

Once a structural survey was completed, works were planned and executed in two stages over four main areas, working from the Northern end to the Southern end of the base. PCB solved the locational challenge by implementing a temporary custom-built boardwalk to provide safe site access to work on both the land side of the wall and on the water’s edge. The platform was relocated along the seawall according to the work undertaken by the team. The wall was co-constructed from hollow core concrete block faces with a synthetic sandstone (epoxy/sand mix), as well as synthetic sandstone capping stones to enhance its aesthetic appeal. Works involved repointing, repairs and replacement of synthetic sandstone (custom-made), replacement of recessed lighting installed within the wall and cleaning of rubble, wall structure and removal of Geo fabric. Environmental services included non-chemical high-pressure cleaning of the sandstone cladded stonework. The wall finishes were also upgraded to ensure this vital structure will be protected from the harsh elements and stand the test of time.