The scope included relocating the main gas feed line to Wellington to enable a new bridge to be installed on State Highway 1. H&B completed the initial HDD design, feasibility and engineering works for the client which involved installing 700m of 250mm diameter steel gas main in one continuous length under the Manawatu River.
This shot had four direction changes including a dog leg bend after the river crossing which brought the alignment from a depth of 15m to only 3m. Ground conditions were running sands, silts, organic material including logs and high salinity ground water at ground level. The protection and integrity of the external coating and weld wraps was critical as was the alignment. The survey peg on exit side was hit dead on with the pilot tool and the coating was in such good condition after pullback the barcode stickers could still be read.
