Transmission Gully, Wellington.
Transmission Gully is a section of the State Highway route north of Wellington, New Zealand.
Warner Construction carried out significant pipeline construction works for First Gas Ltd over a two year period.
Multiple projects were carried out and shown below are several chosen projects: all had their own individual challenges with terrain, weather and construction complexities.
Cannons Creek
Date: 2017
Client: First Gas Ltd
Length: 1,000m
Size: 200NB
Fast facts:
100m realignment of 200NB high-pressure gas pipeline near Grenada North to allow construction of new Transmission Gully Expressway and 250m long Road Bridge.
Steep terrain, narrow right of ways and access way tracks, high voltage overhead powerlines, underground services.
Hard rock trenching.
26m long aerial pipeline crossing.
Utilising WCL own 20T excavator and hydraulic demolition shear removed 300m of redundant gas pipeline.
Paekakariki
Date: 2017
Location: Paekakariki
Client: First Gas Ltd
Length: 745m
Size: 200NB
Fast Facts:
Complex realignment with 3.2m deep trenches.
Hot tap fittings welded at both ends of the installation of isolation staples and tie in wields to the exisiting pipeline at both ends.
The 72mm HDD was welded, x-rayed, gauged, coated and hydro tested prior to being bored and pulled back beneath SH1
Traffic management required to ensure safe set out on location of the drilling head across Highway.
The 550m above ground section was designed to mitigate the effects of an extreme seismic event due to the high potential for liquefaction and large fault lines in the surrounding hills.
Duck Creek
Date: 2017
Client: First Gas Ltd
Length: 555m
Size: 200NB
Fast Facts:
555m realignment of 200NB high pressure gas pipeline near Whitby to allow the construction of the new Transmission Gully expressway.
Complex construction due to the pre-formed terraces, steep 35 - 45 degree slopes and pipe requiring over 3m of cover to allow for the expressway construction.
WCL onsite services:
Bending
Welding
Excavation and back fill
Sandblasting
Painting
Hydrotesting
Gauging & Drying
A 350t and 100t crane were brought in for the lift, crane pads were constructed to allow cranes to reach their full capacity for lift and placement.
Watermain Relocation
Date: 2018
Client: CBP HEB Venture / Wellington Water
Location: Bridge 19/ Duck Creek & Te Maria to Ngauranga Watermain Relocations
Length: 360m & 190m
Size: 915mm OB Concrete lined
Fast Facts:
Each 11.9m length of pipe weighed 4000kg; equipment utilised Warners 25T excavators and pipe layers.
Specialised CAT 320D Crane fit for purpose for unloading delivery trucks and loading pipe trailers at the letdown areas.
Precision installment utilising GPS & GPS rover units for excavation and bedding accuracy.
CSE work carried out
Welding
Pipe handling
Blasting and mortar application inside the pipe at each joint
Wrapping/Shrink sleeve installation
Hydrostatic testing of both pipelines prior to tie in and commissioning
Construction of thrust blocks at each elbow greater than 6 degrees
Flightys Zag
Date: 2017
Client: First Gas Ltd
Location: Transmission Gully #8
Length: 500m
Size: 300NB
