Jabi Drainage Scheme

Jabi flooded every rainy season, and every season the damage moved further up the catchment. The scheme replaced a fragmented network of undersized open drains with 4.5 kilometres of engineered reinforced concrete channels, sized from a hydrological model of the full catchment rather than the failed sections alone.

The work ran through occupied streets. Excavations were opened, lined, and closed in short sections — typically eighty metres at a time — so that no resident lost access to their property for more than a working day. Precast units were used where services congestion made in-situ pours impractical.

The network discharged its first full wet season without a single overtopping event. Maintenance access points were built into the design at every junction, because a drain that cannot be cleaned is a drain that will fail.