The Navigatus study looks at the risk associated with two proposed channel design options compared to today – and the risks associated with a fully laden Suezmax ship navigating either channel option. The study took account of current mitigations in place, such as navigational aids as well as operational measures to be introduced.
Environmental spill risk
The environmental spill study carried out by risk experts Navigatus looks at the risks presented by the refinery proposal for the harbour environment – including the likelihood of an event for every ship transit in the harbour; the difference in the number of ships transiting the harbour; and in the amount that would be spilled in a major event.
Navigatus combined their findings with research on oil spill case studies to determine the overall risk to the harbour environment from fully laden Suezmax ships transiting the harbour.
Existing Harbour Safety Measures
Ship movements are governed by a regional harbour safety management system. A key element of this is the Dynamic Under Keel Clearance (DUKC) system which monitors a range of factors (i.e. ship dimensions, load, swell, tidal movement) to determine whether a ship has sufficient clearance under the keel to enter the harbour safely.
There are a range of internationally established measures to ensure ship safety and protect the environment:
- Crude ships are double hulled to provide an extra layer of protection for the cargo
- Ship tanks are fitted with high level alarms to prevent discharges
- Ships and their crews are vetted to ensure they meet industry standards
In addition the refinery has a number of measures to ensure safety of the ships and protect the environment:
- Electronic aids on our jetties track the speed and direction of a crude ship so it can berth safely
- Jetty hoses and pipes for transferring crude from ship to shore are regularly maintained, with pressure testing of hoses every six months.
In the event of a spill our trained oil spill responders have access to oil spill equipment and are part of a bigger regional response, co-ordinated by the Northland Regional Council (NRC). Regular exercises with the NRC, Maritime NZ and other agencies ensure our oil spill response remains effective.
Independent experts commissioned by Refining NZ carried out a navigational risk assessment that concluded the preferred channel design offers the lowest navigational risk. It is also the closest to full compliance with best practise international guidelines and offers safety improvements on the existing channel.
The experts also completed an environmental risk assessment, which considered the risks of an oil spill occurring in the harbour.
Overall, the experts found the environmental risk will be significantly lower with the proposed channel design and operational measures. The combination of fewer tanker visits plus improved navigational safety will significantly outweigh the risk posed by the greater volumes of oil carried on fully loaded Suezmax vessels.
If you’d like to know more of the nuts and bolts of the effects these are outlined in the summary document here.
You can read further detail on the risk assessments in the related downloads section below.
We’ve spent a lot of time looking at the best possible channel design. Take a Deeper Dive into how this looks here.