Workarounds needed as NZ switches to imported bitumen
The roading industry is confident it will be able to rely on imported bitumen once production stops at the Marsden Point oil refinery early next year.
However, the change is forcing Waka Kotahi NZ Transport Agency to rethink how product quality is managed.
Refining NZ plans to cease production of bitumen from January as part of its plan to simplify its operations and cut costs.
The refinery has previously produced about 110,000 tonnes of bitumen a year which is enough to meet about 70 per cent of domestic demand.
About another 50,000 tonnes of bitumen is imported each year, from refineries as far away as Malaysia.
Different forms of bitumen are used as binders on both asphalt and cheaper chip-sealed roads.
Concerns that roads were melting in the summer and breaking up faster than expected prompted Waka Kotahi to develop a new set of national standards for bitumen, M1-A, in 2016.
Bitumen can pool on the surface of roads when it melts, creating a skidding hazard.
The transport agency’s operations manager, Vanessa Browne, said Refining NZ’s decision meant all bitumen would need to be imported.
Browne did not expect that would have any significant negative effect on road building.
But she said there were risks for Waka Kotahi and local councils to manage ‘‘around ensuring the quality of imported bitumen and how it will be stored and distributed’’.
‘‘Waka Kotahi is updating its specification to allow more flexibility in imported bitumen,’’ she said.
‘‘We are checking on supply for the summer season on behalf of all road controlling authorities, and we are investigating supply options for the future.’’
Stacy Goldsworthy, technical manager of industry association Civil Contractors NZ, said new storage facilities would probably be needed, and some construction was under way.
The Marsden Point refinery made a couple of grades of bitumen that met the NZTA’s specifications, he said.
New rules would give roading contractors the flexibility to import bitumen that was produced to international standards and they would ‘‘then do whatever it takes – add the ‘11 herbs and spices’ – to get that to an M1-compliant product for local use,’’ he said.