The Duggan Sanitary Trunk Rehabilitation project was completed while maintaining full buslane operations and safe pedestrian access to the adjacent school. The work involved sliplining a live 1650mm sanitary trunk and constructing new manhole infrastructure to support future system upgrades, including the decommissioning of an outdated drilldrop connection.

A 3.66m diameter access shaft was excavated to a depth of 22m to reach the deteriorated section of the existing trunk. Working in active flow conditions, crews installed 13m of 1200mm fiberglassreinforced pipe within the existing 1650 mm trunk and secured it with grout.

A new 3000mm diameter HDPElined manhole—complete with a 1200mm stub for future tieins—was cast in place. Above it, 2400mm HDPElined precast manhole sections were installed to bring the structure to surface.

To redirect local flows and enable the abandonment of the existing drilldrop connection, trenchless installation methods were used to construct a new 525mm line from the existing manhole to the newly built structure.