It was suggested that this deep and unusual pit may once have housed pressurised tanks, an idea likely influenced by the number of similar shafts scattered throughout the island’s bushland. Several comparable structures exist near Phillip Point Beach, including two deep pits of similar proportions, one constructed in concrete and the other in red brick. Both are fitted with heavily corroded ladder rails, giving them an appearance similar to access points found in older sewer or service systems.

 

The structure shown here is particularly usual due to its depth and narrow footprint. The timber lining along the interior walls suggests it was designed to prevent collapse in sandy ground rather than to contain machinery. The modern concrete cover and metal grate appear to be a recent safety measure, installed to seal what would otherwise be a serious hazard. Standing at the edge, it is difficult not to consider the risks involved if the timber lining were to fail or if there were no secondary means of exit from the base.

 

While researching the site further, an older map identifies this feature as “Radar Station Well (abd)”. It’s highly likely that ‘abd’ is shorthand for abandoned, a notation commonly used on military and engineering plans once a structure was no longer in service.

 

What this structure most likely was

This structure is best understood as a well or vertical water shaft, constructed to supply freshwater to the nearby radar station and associated accommodation building. Radar sites on Rottnest Island were deliberately placed in exposed coastal locations, often far from existing wells or reservoirs. As a result, dedicated water sources were essential for personnel stationed on site.

 

The timber lining visible inside the shaft is consistent with traditional well construction in sandy or unstable ground. Rather than being load-bearing, the timber acts as a retaining skin, preventing surrounding material from collapsing inward. The depth of the shaft would have allowed access to groundwater from under the limestone surface of the island, while also maintaining cooler, more stable conditions.

 

Unlike fuel tanks or pressurised systems, which typically require reinforced chambers, pipe penetrations or mounting fixtures, this shaft shows none of the structural features associated with mechanical installations.