This week’s wild and wintry weather in New Zealand not only caused the evacuation of over 1000 people from their homes and left many more without power in the central and lower North Island, it cut gas supplies to the Hawkes Bay and left the region’s big users in a major quandary.
One of the region’s biggest employers, Heinz Wattie, says it has had to shut its two boiler plants and the loss of gas supply is endangering the work of many of its 1000 Hawkes Bay staff.
Large Hawkes Bay gas consumers have had to curtail their gas usage because of the disruption to local supplies caused by the Sunday night washout of the Pohangina road bridge near Ashurst in the Manawatu.
The washout has left the gas transmission pipe in a precarious position and valves have been shut to isolate this section of pipeline. As a consequence, no gas is flowing into Hawkes Bay and supply is entirely reliant on the remaining gas pressure (linepack) in the pipeline system.
NGC has asked Contact Energy to cease gas supplies to all but essential services and residential customers, with linepack gas being reserved for Hastings hospital and other emergency services.
Ashurst and all communities to the east, including Pahiatua, Mangatainoka, Dannevirke, Takapau, Mangaroai, and the twin cities of Hastings-Napier, have been affected.
NGC spokesman Keith FitzPatrick said NGC was working on a number of engineering options to restore gas supplies at the earliest possible time. A specialist engineering team had completed a survey of the damaged pipeline section over the Pohangina River and was “firming up” proposals for both temporary and permanent solutions.
NGC is inspecting and assessing the still partially submerged pipeline today. If the pipeline is suitable for recommissioning, it can be restored to partial operating pressure, sufficient to supply the region’s normal demand, by the weekend.
However, while additional work will be done to help secure this line, it will not be restored to its original state and remains at risk of failure. Therefore, NGC is also working on a temporary river crossing, with new pipe and related equipment expected to arrive from Taranaki today. New pipe will be laid in a trench if piling is not possible.
FitzPatrick said this temporary crossing could take about 10 days to construct and would ultimately replace any use of the existing line.
Design and engineering requirements of temporary tie-in options, as well as the construction of a permanent trenched crossing downstream from the current location, were also being done.
