- Installation of retaining wall structures at pipeline ends above/below ground interface
- Construction of surface contour drains
- Installation of buried subsoil drains, drains, MH and Sumps
- Construction of a concrete pipe support structure
- Excavation of the pipeline to remove existing backfill materials
- Removal of the existing coating on the excavated section of pipeline and recoating
- As-built survey of the pipeline location, coating and drainage
The DN750 Oaonui-Rotowaro Gas pipeline (known as the 400Line) runs along the coastal strip in North Taranaki. The pipeline was subjected to a Loss of Containment (LoC) event in October 2011. Following this an initial repair replacing a section of DN400 pipe took place and included coating repairs before backfilling the pipeline.
The re instatement project retains the asset as a permanently above-ground facility. This involves full excavation of 45 metres of pipeline; installation of one concrete plinth and an inspect-a-lift pipe support; re-coating work; associated drainage; installation of retaining walls and permanent batters of trench.