The Outcome
Hartigan was engaged early on to design and manage the enabling works including drainage, demolition, and complex substructure tasks, followed by the full design of the superstructure for the project. A site investigation revealed poor ground conditions, leading to the decision to use driven steel piles, some over 14 meters long. Pile caps and ground beams provided the foundation for the reinforced concrete frame, which included RC columns, flat slabs for the upper floors, and a podium slab that also served as landscaped amenity space.
How we did it
The principle of the design is a reinforced concrete structure of columns and flat slabs, with stair and lift cores providing stability, a podium slab transfers the load to the lower columns, which transfer the load to ground beams and pile caps on to piled foundations. The townhouses, like the main apartment blocks, were designed utilising piled foundations with a reinforced concrete ground slab with a timber framed superstructure. The pile foundation system was selected to accommodate the loads of the new structures in the challenging ground conditions but also to avoid the influence of the load from the new structures on to adjoining properties.
The Challenge
The site is formed on geology with a high-water table and this was taken into account in the design process. Information from the intrusive site investigation as well as drain surveys and a geophysics survey identified that a gravity drainage system was not feasible. Therefore, a large attenuation system was designed which collected the surface water from the site and stored in large tanks before being pumped off site in a rising main to the nearby surface water sewer. The construction stage fell during the COVID-19 pandemic, the site visit and meetings were limited and it required to resolving various queries or checking construction stages using video calls and photographic documentation.
