Ōrākei Main Sewer repair and relining

Sinkhole and sewer repair  

The repair involves pipe-jacking a series of liners into the damaged sewer to restore full strength and flow capacity. Installation of the liner and grouting is now complete. This work involved workers entering the sewer. As this is a live environment, this work must take place at night when flows are lower, they are also not able to work when it rains as this is a combined sewer conveying both wastewater and stormwater. With approximately one more week of night works to complete last works in the sewer (weather dependent), we will soon commence the reinstatement of the sinkhole area in the carpark. Please note, pedestrian access across Alberon Reserve has been reopened. Please follow the signage on-site.

The temporary pumps in St Georges Bay Road and the bypass pipeline will begin to be removed from September. Full reinstatement of the area is estimated to be complete by the end of the year.

Stage 2 relining

Over the past few months, we have been undertaking a condition assessment of the remaining 9km of the Ōrākei nain sewer to help mitigate the risk of future failure. The condition assessment has identified the need to rehabilitate further sections of the ageing pipeline.

The next section, stage 2 works, will involve access via a deep shaft in the northern section of Alberon Reserve and relining of the sewer between manholes 14 and 15 (refer map below) with glass reinforced plastic liner. This technology will enable the Ōrākei main sewer to continue in service for another 100 years.

Site preparation for stage 2 will begin from 1 August including establishing a construction support area in Alberon Reserve (refer map below) . A 13m deep shaft will be constructed beginning in September to enable access to the Ōrākei main sewer for relining. Further stages of works will include debris clearance (night works), sewer relining, grouting (night works), and stage 2 site lock up.

It is anticipated that stage 2 work should be completed by April 2025. The laydown area to support the construction works within the Reserve will remain for access for stage 3 works, commencing September 2025.

During construction Alberon Reserve walkways will remain open, however there will be sections of the Reserve which will fenced off for health and safety. While these parts of the reserve are fenced off, access between Alberon Street and St Georges Bay Road will remain as well as the pathway between Alberon Place and Havana Coffee. The southern section of the reserve will remain open for normal recreational use. Further details of the layout are shown on the map below.

Future relining

The deep shaft at manhole 14 will remain open after the completion of Stage 2, as it will be a key access point for Stage 3 relining works between manholes 14 and 13. Stage 3 is currently being planned and is anticipated to begin from September 2025. As this is a live environment conveying wastewater and stormwater in a combined sewer, we are unable to work safely over the winter months when there is increased rain, increasing the volume of fluid in the sewer.

Stages 4 and 5 of relining are being planned for future years and will not be located in Alberon Reserve.