MANGERE EAST BRANCH SEWER

Photo: (top) Ditch Witch JT8020 drilling rig pad for 560mmOD motorway crossing. (below) 560mmOD PE pipe string welded and ready for installation under the motorway. (bottom left)  Triflo mud cleaning system and PitDry solidification machine ready to process drilling slurry.

The Mangere Branch Sewer project involved two difficult trenchless installations comprising separate drilling rig setups. The first was a 106m installation of 630mmOD PE under a four lane motorway and off ramp on SH20 adjacent to Bader Drive.

 

On this installation a new bore monitoring device was used to log the tensile forces applied to the pipeline during pullback and also the internal bore fluid pressure. This information is transferred to the operator in real time which was invaluable in ensuring that the bore pressures did not exceed the estimated overburden and cause heaving of the carriageway. It also gave the client confidence that the pipeline had been installed without being over stressed and would be fit for purpose.

 

The second installation was 326m of 560mmOD PE under Bader Drive and into a reserve. Both installations were installed on time and within budget. The installations were both made at grades of less than 0.5%.