WATCH: CDS NZ shares video of complex HDD project

CDS New Zealand has shared footage of a major horizontal directional drilling (HDD) project in Auckland.

A 200mm network watermain supplied drinking water to around 357 homes in the Glenbrook Beach region – an area experiencing rapid population growth.

But the pipe, which was anchored to the seabed, was subject to significant tidal influence and this compromised its integrity over time.

The original pipeline experienced a joint failure that led to the pipe dislodging and floating to the surface of the Taihiki Estuary.

The emergency prompted Watercare to establish a temporary solution, and subsequently, a permanent replacement project was conceived to ensure a resilient long-term water supply for the Glenbrook Beach area​​.

To deliver such an outcome, Watercare partnered with CDS New Zealand Ltd, an expert in HDD.

Check out a video on the project from CDS NZ here:

“The project was quite complex, entailing three parallel 750m crossings beneath the Taihiki Estuary,” CDS Engineer Marc Carmody said.

By engaging the services of Highside Drilling Services, CDS achieved added confidence in the pilot bore steering capability utilising the ParaTrack 2 guidance system.

Environmental features such as cliffs, as well as the length of the crossings, also forced CDS to think laterally.

Rather than following the old pipeline alignment – which would have been the easy decision – CDS opted to chart a new and slightly longer alignment that kept the project clear of a cliff, keeping contractors and future maintenance workers safe.

“Another challenge we faced was the length of the crossing, which would have put more pull force on the relatively small bore pipe than we were comfortable with,” Carmody said.

“To remedy this, CDS calculated pipe pull forces and switched to a larger, non-typical pressure rating, PN25 pipe, which was strong enough to safely handle the crossing.”

Rising to the challenge, CDS mobilised to site in April, with the final crossing installed in early September.

The company has shared a video of behind the scenes work at the project, which became operational in recent weeks.