Autohaus Newstead

The challenge.

The Autohaus Newstead development is a seven level car dealership and mixed use commercial development with a single level basement, located on the bank of Breakfast Creek in Brisbane. The site presented a complex geotechnical profile with soft alluvial clays extending to significant depths, a high groundwater table influenced by tidal conditions, and significantly sloping rock level across the footprint. Historical flooding and constrained access during investigation (prior to demolition) further increased project complexity.

The approach.

FSG undertook staged investigations to progressively build a reliable ground model despite access constraints. This included boreholes, CPTs and targeted laboratory testing to characterise soft clays, groundwater behaviour and the variability in the underlying rock.

Engineering judgement focused on translating variable subsurface conditions into practical design inputs. Key considerations included constructability of excavations in soft soils, the impact of groundwater on excavation and retention, and managing variability in rock depth across the site. FSG provided clear, actionable guidance on feasible foundation systems, temporary and permanent retention approaches suited to the site constraints and performance requirements.

The outcome.

FSG’s investigation and interpretation provided a robust geotechnical model to inform design and procurement The work enabled confident selection of deep foundation solutions transferring loads to competent rock, while identifying suitable basement retention strategies capable of managing groundwater and minimising movement risks.

By clarifying subsurface variability, construction risks and practical constraints early, FSG supported informed decision-making and more predictable project delivery outcomes.