The harbour crossing will connect Memorial Park pump station to the Matapihi section of pipeline that has already been constructed. The harbour pipeline will be drilled at a depth of 15 – 40m under the harbour bed. It will go in a direct line under the harbour from Memorial Park across to the end of Matapihi Road.
The harbour crossing pipeline will actually be two pipes, a high density plastic pipe that is contained inside a thick steel outer pipe. This outer pipe is made from high grade steel. The interior pipe is made of welded high density polyethylene pipe (PE). Polyethylene pipes performed very well in the Christchurch earthquakes.
Length of the harbour crossing: 1570m
Size of outer steel pipe: 1200mm diameter (approx.)
Size of inner pipe: 800mm (approx.)
Depth: 15 – 40m below the harbour bed
An earlier plan was to lay the pipe in a scoured trench along the harbour bed alongside the rail bridge. This plan has been superseded by improvements in drilling technology. It is much less invasive to the harbour bed to drill the pipe deep under the harbour and this way there is no contact with the harbour waters.
Safety of the harbour crossing pipeline
It is unlikely that the interior pipe will ever have a major break. If that does happen, flow meters at either end will raise an alarm in the control system which will shut off the pumps. If the leak is too minor to be detected by the flow meters, it will be contained in the outer steel sleeve of the double containment system.
The double containment system means that if a leak occurred in the interior pipe it would be contained and can be pumped to the end of the sleeve.
The inner pipe can be repaired or replaced if needed.
A drill rig will be set up at one side of the harbour. It will drill 15 – 40m under the harbour, pulling the outer steel sleeve through. Once the steel sleeve is installed, the inner pipe will be pulled through. The harbour bed will remain untouched.
Contractors are expected on site in March 2017. Construction is expected to go from March 2017 – December 2017
Impact on Memorial Park
During construction Jordan Field (the northern part of Memorial Park) will be closed to the public and will be fenced off. It is likely to be a staging area for steel pipes, PE pipes and construction machinery.
When the harbour crossing is finished there will be some more construction required in Memorial Park to connect the harbour pipeline to the Memorial Park pump station.
Impact on Matapihi
The cul-de-sac at the harbour end of Matapihi Road will be closed to traffic. The closure will be for quite a few months through 2017. The road is not wide enough to keep the road open and safely construct a pipeline at the same time.
The end of the road will be fenced off as a construction site. There will be access for residents who live beyond the construction site.
A temporary parking bay will be created at the top of the hill.
Pedestrian access will be maintained for walking and cycling between the road and the rail bridge.
Tauranga City Council has resource consent and Heritage New Zealand authority to work in the road reserve. The pipeline construction activity will take place in this narrow strip of road reserve with usual iwi monitoring protocols. Construction activity will not encroach into the pa site to the west of the cul-de-sac, except to reinstate a sea wall.
The Council’s consent application keeps the drilling entry/exit points away from the high water mark on both sides of the harbour. The exact location will depend on the contractor’s methodology.
Heritage and cultural issues surrounding the road reserve are paramount.
Last Reviewed: 28/11/2016