The final piece of Auckland’s Central Interceptor tunnel is in place, following the removal of the bulkhead that separated the two halves of the tunnel during construction.
The bulkhead removal was carried out at the project’s May Road site in Mount Roskill.
The glass-reinforced plastic and steel bulkhead was installed in 2024 to seal off the southern half of the tunnel ahead of it going live in early 2025, to protect the crew working in the northern part of the tunnel.
The removal operation took weeks of planning to ensure it could be done safely. Specialist divers from New Zealand Divers and Salvage were engaged to provide expertise and the protective equipment needed for the crew to work in a live sewer.
“The success of this complex work relied on continuous monitoring, clear communication between all the teams involved, and strict adherence to our safety plan,” said Watercare lead engineer Emmanuel Vaki.
Although the bulkhead was installed in the tunnel as one piece, its components were removed separately and lifted out of a 70m-deep shaft at the May Road site. The glass-reinforced plastic “dome” was the final piece to come out.
A gantry was mounted on a small vehicle and driven into the tunnel to support the dome while the metal body of the bulkhead was removed. Once the dome was ready for removal, it was towed out on the gantry vehicle before being lifted out of the shaft by a crane.
The crew repaired the liner of the tunnel where the bulkhead had been bolted and sealed in place.
The bulkhead removal was the last major construction milestone for the project before the 16.2km tunnel becomes fully operational this year. The southern half of the tunnel has been live since the start of 2025.
