From the magazine, HDD

The challenges installing HDPE

For the past 80 years, an old above ground 900 mm steel pipeline had been linking the Hunter’s water network, transferring water between two separate catchments. However, the pipe and existing pipeline route were causing significant problems:

  • The old pipeline path was prone to flooding, causing significant damage to the pipe structure and therefore requiring regular repairs;
  • The pipeline route was going through valuable and sensitive wetland environment at Hexham Swamp Nature Reserve;
  • The pipeline had started to cause safety and environmental concerns, such as deposition of lead fragments in the soil next to the pipeline from the lead collars used to secure joints.

A replacement pipeline was planned to provide secure and reliable water.

Going underground

Laying the pipeline underground would deliver an effectively maintenance-free and flood-proof system, and increase water pressure. An underground route would also improve the localised flows, and increase the extent of tidal inundation in the western section of the wetland.

Project challenges

One of the major project challenges was installing the pipe under the Ironbark Creek. Directional drilling was chosen for this part of the project and 1,000 mm PN16 HDPE pipe supplied by Zest was selected as the material of choice. Horizontal directional drilling (HDD) requires the installed pipe to be flexible, strong enough to withstand all forces (pulling, bending) during installation, abuse-resistant to scratches, and smooth for ease of installation.

Zest’s HDPE PE100 is ideal for HDD as HDPE’s basic material properties make it abuse resistant, including:

  • toughness and impact strength
  • slow crack growth resistance
  • rapid crack propagation resistance.

HDPE also meets the criteria for the installation specific performance:

  • lightweight
  • flexible
  • able to handle long lengths of pipe
  • joint reliability – butt fusion joints
  • tensile strength sufficient for pull-back
  • leak – free structure
  • installation methods available to connect HDPE pipe to steel pipe.
Send this to a friend