12 Cross Street, Double Bay
Project Background
Perfectly positioned in the heart of Double Bay, this landmark site will be thoughtfully transformed into a mixed-use address, pairing refined residential living with vibrant ground-floor retail. Designed to enrich the fabric of the neighbourhood, it embodies the meticulous attention to detail and considered approach that define every Fortis development. The finished building, currently under construction, will comprise ground floor retail and 5 stories residential accommodation above plus 3 basement levels with a sophisticated car-stacker arrangement for off-street parking.
The planned basement excavation 11m below ground level in loose sands with a high water table, surrounded by sensitive buildings and infrastructure presented a significant challenge to meet Council’s strict controls. The site’s small footprint meant that dewatering infrastructure had to be as small as possible to contain it on site. Structural Engineering design required calibrated B3 slab movements under loading and at final stage with dewatering turned off.
Site Conditions & Challenges
Our team quickly identified an issue with the planned basement shoring and dewatering systems and conducted sophisticated 3D groundwater modelling for different shoring configurations. A data gap in rock levels across the site was addressed by further investigation that was arranged and completed in an extremely short timeframe. We also conducted 3D modelling of the soil/structure interaction for the B3 basement slab to provide a deflection profile to the Structural Engineer for calibration of their structure model.
Aretas’ Approach
The groundwater modelling directed the project team towards and complete rock cutoff solution that would provide a robust shoring solution and provide the lowest risk for site dewatering, satisfying Council’s requirements and minimising dewatering plant. This action saved the project many months of construction delays and additional costs. The additional investigation provided rock contours across the site for design and construction of the shoring walls. 3D modelling of the structure was completed using the calibrated displacements from our 3D soil/structure interaction model.
Results Delivered
