Contracted by HPAC NSW Pty Ltd, Chalouhi undertook the preconstruction works for the development of the new Sporting Complex at Wahroonga’s Adventist School. The scope of works for Stage 2 & 4 of the project comprised of the demolition of an asphalt carpark, installation of foundation piling for a pavilion area, the design & construction of a customised 400 meter square sandstone retaining wall and cut & fill earthwork operations. All works were completed with careful consideration to the surrounding live school environment, ensuring minimal noise and dust impact.
Comprehensive deep excavation works were critical to meeting the unique design and construct specifications of the sandstone retaining wall. The technical and structural constraints exposed in the initial gabion wall design prompted for an alternative and more suitable sandstone retaining wall sketch designed by our in-house engineering team. Working closely with geotechnical consultants, various test strips with different methods of compaction and assortments were conducted to certify the new structural design. The design of the footing accommodated for the water ingris and the numerous “multi directional’ pipes present on site.
The staging of the project was critical in allowing for both the backfilling and the compaction of the retaining wall to be conducted simultaneously for an accelerated delivery of the project.
Large sandstone blocks were placed individually and staged to allow backfilling and compaction works to raise the natural ground to the required level. Sandstone block nails were utilised to anchor the retaining wall for structural stability and a Sandstone Rip Rap backfill method was applied to add additional weight to the wall. Furthermore, as the area of the footings was extremely damp, the Rip Rap Sandstone backfill was mixed with ‘fines’ wrapped in geofabric. This allows for water to be drained through whilst still providing a structurally sound footing and a sturdy base.
Stringent sediment and environmental control measures were adopted to prevent any environmental risks to the “Natural Reserve Area” present in close proximity to the retaining wall. A Hay Bale Berm was also installed to avert stockpiles and water from entering the reserved land. Additionally, with stockpile overhaul present on site, the Chalouhi team installed excavation ramps to permit plant access to the retaining wall allowing for the operation of multiple machinery on site possible.
Despite the Wahroonga project staging itself as an effortless project, the unforeseen site conditions of a neighboring environmental Reserve, unpredicted pipelines, a sewer line and the presence of water on ground were successfully overcome by the Chalouhi team. Our engineering team closely collaborated with architects, consultants and council in managing these latent conditions. This allowed our qualified team of supervisors and labourers to successfully complete the scope of works.
Chalouhi embraced the challenges and demands presented on site and showed exceptional team support and enthusiasm throughout all stages of the project.
