STRONG YET DISCRETE SHORING SOLUTION SUPPORTS RIVERSIDE EXCAVATION
Reflections on Bradman is a boutique residential development currently under construction on the Sunshine Coast – 2km northeast of Maroochydore CBD. The 4 storey development will feature 15 architecturally designed apartments overlooking the Maroochy River.
Reflections on Bradman is Sea Vista Development’s first foray into delivering a multi-residential property with a basement. Two main factors complicated the excavation and construction of this single-level basement:
The basement takes up a relatively large area on the site. This required temporary works to be installed and excavation to be performed very close to the boundary – on a site bordered by properties on three sides.
The property’s riverside location and the need to excavate in ground conditions within the water table also meant that a solution for extracting and treating groundwater was required.
The client relied on Coates Hire’s vast experience delivering turnkey solutions to help progress work on site.
In December 2019 Coates Hire completed the design, certification, supply and installation of robust temporary works solution for Reflections on Bradman. The successful 960m2 sacrificial sheet piling system supported the safe excavation of the basement and enabled construction to commence.
To allow for the natural discharge of groundwater on site, Coates Hire also designed, supplied, commissioned and continues to maintain a sump-dewatering package and water treatment system.
The relatively large building footprint and proximity of neighbouring properties presented a major challenge and influence on the temporary works design for Reflections on Bradman.
“Sacrificial cantileavered sheet piling was the ideal solution for the basement retention,” explains Travis Loors, Product Specialist – Services, Coates Hire. “This system provided considerable strength with minimal site impact. It also allowed for excavation work to be performed very close to the boundary without affecting the integrity of surrounding properties.” Travis continues.
Ensuring the constructability of the client’s design was also paramount.
“If a hydraulic bracing system had been implemented, Sea Vista would be faced with constructing walls where the struts were positioned, hindering construction,” says Travis. “Instead, this sacrificial self-supporting retention system enhances the integrity of the basement long after excavation, and creates an open space allowing construction to commence – providing a far more practical and flexible solution for the client.”
Reflections on Bradman’s lift shaft and basement sit at the top of the water table, where groundwater is present. Coates Hire’s comprehensive water management and treatment solution resolved this issue, allowing for safe excavation and the clean discharge of all groundwater back into the neighbouring Maroochy River.
“Once the dewatering process has occurred, all groundwater is subjected to chemical treatment and filtration. This process adjusts the pH and removes suspended solids and some heavy metals, before discharging it back into the natural river system.” Travis explains. “It can be quite hard to distinguish between the water we’ve treated and discharge, and the bottled water you would buy from a shop,” Travis continues.
In delivering the groundwater solution, the size of the basement’s footprint and proximity to the boundary once again presented a challenge. “We had limited space for placing and operating equipment,” says Travis. “To allow enough space for the excavation and basement construction to take place our water treatment package fit neatly into one corner of the block.”
Coates Hire continues to maintain the groundwater management and treatment solution until all relevant groundwork is complete.
A safe pair of hands
Reflections on Bradman is Sea Vista’s first experience delivering a residential basement – but according to Sea Vista Project Manager, Tristan Begg, it won’t be the last.
“We engaged Coates Hire to assist quite early on with Reflections on Bradman, to supply and install a sheet piling solution and to provide water treatment and groundwater management for our basement excavation,” says Tristan. “Coates Hire was able to successfully assist us with this scope of work, delivering a large scale project with competitive pricing.”
“From product specialists to boots on the ground, Coates Hire brought a huge amount of experience to our project,” Tristan continues. “And the communication Coates Hire facilitated from start to finish was second to none.”