Seven Hills Industrial Subdivision
Seven Hills Industrial Subdivision is a 7-hectare development that transformed a former industrial site into 17 serviced lots for bulky goods warehousing and manufacturing use. Previously a chemical manufacturing block, the site required cut and fill earthworks, partial remediation and complex retaining walls works on a steep and narrow title between existing industrial complexes, with buildings close to boundary lines. Working under a design and construct contract, the scope included bulk earthworks, stormwater management, estate roads, multiple external intersections with acceleration/deceleration lanes and upgrades to the internal roads in coordination with council and RMS traffic signaling authorities. The project required careful environmental controls, extensive noise and vibration management for neighbouring precast properties on the boundary walls, adjacent offices, and detailed traffic staging to maintain access for surrounding tenants throughout the construction.
Alternative construction approach due to close proximity to buildings on boundary walls
The project required substantial retaining walls (some up to 6m high) to be constructed on steep slopes which were located directly next to existing industrial buildings and active car parks. Co-Infra identified that standard construction methods using high-energy mechanical compaction or continuous excavation risked creating high vibration levels with the potential to damage adjacent structures and disrupt tenant operations. To address this, Co-Infra developed a specialised approach including adopting low-vibration compaction methods, reducing lift thicknesses and using multiple light passes to achieve the required compact fill density. Alternative methods included live vibration monitoring, and prioritisation of low-impact excavation near sensitive structures. This ensured that neighbouring assets were protected throughout construction.
Managing busy road upgrades without disrupting access
Park Road, a key access route for surrounding industrial properties, required widening and new acceleration and deceleration lanes with full intersection upgrades linked to RMS traffic signals. Total road closures were not possible as the road serviced active businesses that required uninterrupted access. We addressed this by developing a detailed staged construction methodology that split the work in half to maintain at least one operational lane at all times. The Co-Infra team was responsible for preparing comprehensive traffic control plans, demonstrating how access to neighbouring properties could be achieved and getting them approved by Blacktown City Council. This was further supported by carefully sequenced staging to minimise disruption, including coordinating with RMS to manage changes to traffic lights and signal phasing. This process involved Council pre-start meetings, ensuring all stakeholder concerns were addressed successfully and allowing local businesses to remain fully operational.
Delivering the project on time with no builder variations
To help the client maintain cost certainty, Co-Infra delivered this project under a lump sum approach, raising no variations or time extensions aside from client requests. To achieve this, the team committed to agreed program milestones with the client. A key constraint to achieve this was Council acceptance of the Road Asset handover. We faced challenges such as cracks in the sewer pipelines, which we identified with CCTV robot pipeline, we then repaired this upon client approval. This was completed within a short timeframe during which we could have possession of the road and stormwater assets. By mitigating these challenges through early identification of issues and innovative methods we were able to complete this busy project on time with no builder driven variations.
