20180119 145931 v2

Gravity Stormwater Pipe installed by HDD

Civil Case Study

Low Impact Installation with Restrain™ Segmented DN225 SN16 PVC-U Pipe

A new residential subdivision in Totara Heights, Auckland required a quick & low impact installation of a Gravity Stormwater pipeline carrying stormwater from a new manhole to a discharge point ~81 metres on the edge of the property boundary.

A steep sloping section with pre-existing surrounding retaining walls, along with a deep level to the proposed pipe invert meant that an open cut installation was impractical for the sloped (and retained) section of the installation site.

A trenchless installation methodology was heavily favoured. Heavy construction in the adjacent property imposed restrictions on the temporary set-down of a long pipeline, which meant a solution utilising a fused PE pipe was impractical.
Iplex Restrain™ was a perfect solution in this situation. 3m pipe sections with threaded sockets and spigots were lowered into a safely shored pit; installed one section at a time and pulled through the drill hole. In all 21 sections of pipe were installed from the manhole location to an intermediate location after the retaining wall. The remaining 6 sections of pipe were installed in shallower ground using an open cut installation methodology.

The contractors were very experienced in using Polyethylene pipe in trenchless installations, but had not used Restrain™ previously. Iplex were able to provide on-site installation support during the job, providing guidance on suitable installation tools and equipment, as well as advising on specific aspects of Restrain™.

The crew were impressed with the efficient installation outcome using Restrain™ and were pleased with the positive end result.

The pipeline installation took place during January 2018.

Contractor: Pipeworks
Council: Fletcher Living – vested asset to Auckland Council