Drilling begins for major Tauranga project

A construction worker at Matapihi with part of the Southern Pipeline. Photo/file

Drilling under Tauranga Habour has begun as construction on the Southern Pipeline reaches a milestone.

The drilling will take place between Matapihi and Memorial Park, where works have been held for several months already.

Tauranga City Council project manager Steve Wiggill said the wastewater pipeline project was tracking on time and to budget.

"We're on track for completion in December as scheduled. The noisiest part of the project is complete, and we want to thank the community for being patient during this time. We've been working closely with residents who live close to the site and listening to their feedback to ensure we minimise disruption as much as possible while this important work is completed."

Work to drive large outer steel casing sleeves into the harbour bed finished this week at Memorial Park, with the driving work at Matapihi finishing several weeks ago. This was the noisiest part of the project.

Drilling has now started at Matapihi to create a route across to Memorial Park, 35 metres underneath the harbour bed. This is done using a method called Horizontal Directional Drilling which is the least invasive for the environment. Drilling will continue for around four weeks.

Sections of pipe are being welded into strings up to 450m long and stored along the side of Memorial Park. This welding work is continuing into the evenings. Noise from the welding work is minimal and super silent generators are being used, the council said in a statement.

Once the harbour drilling was completed, the welded steel pipes would be winched through to Matapihi from Memorial Park. Polyethylene wastewater pipe would then be pushed through inside the steel casing. The steel casing would provide a protective layer between the wastewater pipe and the soils deep under the harbour.

The entire project is scheduled to be completed in December 2017. Both construction sites at Matapihi and Memorial Park will be returned to their original states once the project is finished.

More information about the Southern Pipeline

The $21 million harbour crossing is the final stage of the $99 million Southern Pipeline project, one of several key infrastructure projects being built to cater for the rapid growth being seen in Tauranga.

The pipeline will relieve pressure from the Chapel Street Wastewater Treatment Plant by redirecting much of the city's wastewater to the treatment plant at Te Maunga, which has extra capacity.

It will connect the wastewater network between Memorial Park and Matapihi through a pipeline deep beneath the harbour bed, at a depth of up to 35m.

Southern Pipeline construction started in started in 2009. The harbour crossing construction began in February 2017. The entire Southern Pipeline project is due to be completed and functioning at the end of the year.