The Eastern Interceptor is a critical component of Auckland’s wastewater transmission infrastructure. Originally constructed in 1962, this 19km reinforced concrete trunk sewer conveys around 60% of Auckland’s wastewater from Okahu Bay to the Mangere WWTP.
Sections of this asset had suffered significant concrete degradation due to hydrogen sulphide attack. Concrete had delaminated and reinforcing steel was exposed and corroded. In order to prolong the asset life and ensure continued reliable operational performance, Watercare decided to rehabilitate two specific sections of degraded concrete and steel.
The rehabilitation was achieved by using high-pressure water-blasters (hydro-demolition) to clear away degraded concrete and contamination, tie in new supplementary reinforcing steel where required, and then apply Sewpercoat HS2000 to repair the sewer wall.
Watercare partnered with Aecom and BBR Contech for delivery of this project. Due to the criticality of the Eastern Interceptor, the work had to be delivered with the asset remaining in service at all times. This project team worked collaboratively to manage this project safely and effectively in what was an extremely hazardous construction site. This included managing confined space risks, odour control, operational flow regimes, and working with sensitive stakeholders.
This paper demonstrates how a complex rehabilitation project can be delivered safely and effectively on a critical infrastructure asset while remaining in operational service.