Mount Roskill
Drainage Works and Detention Tank
Full civil and drainage delivery for 8 social housing units including stormwater and wastewater networks, deep trenching, retaining, and AT footpath reinstatement within a constrained urban site on a busy road.
We delivered the civil, drainage, and infrastructure package for this compact 8-unit social housing development in Mt Roskill - a challenging brownfield site bordered by existing homes, mature trees, and live services.
The works began with bulk excavation and trenching in variable clay and ground conditons, followed by the installation of stormwater and wastewater networks connecting into the public mains under Auckland Transport (AT) corridor supervision. Several sections required deep trenching and bench excavation, with groundwater management and shoring in place to maintain safe access and structural stability.
We constructed new manholes, stormwater treatment devices, and outlet connections, coordinating daily with AT and Watercare inspectors to maintain compliance and avoid disruption to neighbouring properties. The project also included timber retaining walls, Cirtex detention–soakage hybrid system, and council footpath reinstatement after service tie-ins.
Tight access, narrow street frontage, and live utilities demanded precise sequencing and communication between trades -Â a recurring theme in urban infill projects.
Despite weather interruptions and subgrade variability, we achieved practical completion within the building programme, leaving a serviced, stable platform ready for vertical construction.
During the works:
- We installed new stormwater drainage and manholes, trenching carefully through varying ground conditions to connect into the existing network.
- We backfilled and compacted trenches in controlled lifts, placed bedding and surround material to protect pipe integrity.
- We extended new wastewater lines and water mains, coordinating tie-in points with the existing system.
- Retaining formed part of the scope: the site required careful earth retention and cut-and-fill to achieve desired finished levels.
- We prepared service trenches ahead of building works, ensuring final asset locations were accurate to coordinate with future slab penetrations.
- Traffic management and adjacent property interface had to be carefully managed given the site’s suburban frontage and neighbouring private property.
- We oversaw final surfacing and site remediation of disturbed areas (verge reinstatement, footpath reinstatement) post-installation.