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Marine oil spill risk assessment

Risk assessment underpins all preparation and planning for marine oil spill response in New Zealand. It includes the assessment of both the likelihood of a spill occurring and the consequences or effects of the spill.

In 1992 a national risk assessment was completed for New Zealand. This established the basis for the first New Zealand Marine Oil Spill Response Strategy. In 1998 the Maritime Safety Authority completed its second national marine oil spill risk assessment. The purpose of these risk assessments was to provide further information on:

  • The level of risk of oil pollution of the sea, coastline and ports of New Zealand;
  • The proportions of overall risk which specific oils contribute;
  • The proportion of overall risk which specific maritime and oil industry sectors represent; and
  • The consequences of a spill on people, their values and the marine environment.

The first assessment did not address the possibility of an unpredictable catastrophic spill, however, the 1998 assessment did.

The 1998 risk assessment measured and presented marine oil spill risk in a manner similar to that used for other forms of emergency response. The probability that a spill event of a particular size occurring in any given year (Probability of Exceedance Level or PEL) was estimated and assigned a value.

The 2004 risk assessment demonstrated that while there had been some changes of the risk profile at the national and regional level, overall the risk profile had been predicted. There was a small increase in the volume of crude oil imported to Marsden point, but overall there were a smaller number of ship visits as the overall size of the tankers had increased. There was also a shift in shipping patterns with the change occurring in the type of vessels for container traffic.

These early risk assessments concentrated upon the chance of oil spills occurring and although mapping environmental sensitivity did not combine the calculated probability with the potential impact of oil on the coastline. The current risk assessment does this, and when combined with the greater level of environmental mapping gives an output that represents environmental risk.

The environmental mapping conducted as part of this current assessment draws on the considerable work done since 2004 (and in part initiated by the findings of that work) by MAF BioSecurity. Although that work is not reproduced directly, here, the critical value of the early BioSecurity work is acknowledged.

The risk assessment that underpins the information depicted by this web site forms therefore the fourth assessment of oil spill risk to the New Zealand coastline. This risk assessment, is the most comprehensive assessment of risk that has been conducted.

The nature of the offshore oil and gas exploration and production industry changes more quickly than the overall shipping patterns. The Taranaki fields are increasing in production with two FPSO's and several well head platforms now in situ. This necessitated a re-evaluation of the risk profile for the Taranaki region and this is reflected in the current risk assessment.

Further, and as a result of the work undertaken on the oil pollution levy review, there is a more complete data-set of the movement of oil around the New Zealand coastline. This data tends to support the conclusions of the 2004 risk assessment.

Also the regional work undertaken on the Port & Harbour risk assessments and safety management systems since 2003/04 is significant to this current risk assessment.

The 2009 Risk Assessment should build on the previous assessments accounting for any new trends and include the oil pollution levy data.

Supporting Information

The Maritime Transport Act (MTA) (1994) requires the Director to develop and maintain the NZ Marine Oil Spill Response Strategy (The Strategy). This describes how New Zealand will efficiently and effectively minimise the impact on the marine environment of oil pollution from ships and transfer sites. The Strategy recognises the need for the national spill response capability to reflect the current risk profile with the risk assessment underpinning this need.

The purpose of this most recent risk assessment has been agreed to by the Oil Pollution Advisory Committee (OPAC) as the need to provide further information on:

  1. the level of risk of pollution of the sea, coastline and ports of New Zealand;
  2. the proportions of overall risk which specific oils contribute;
  3. the proportion of overall risk which maritime and oil industry sectors represent; and,
  4. the consequences of a spill on people, their values and the marine environment.

The purpose of the Strategy as laid out in s284 of the MTA is to:

  1. describe the actions to be taken and by whom the action is to be taken, in response to a marine oil spill in NZ waters; and,
  2. promote a standard response to marine oil spills in NZ; and,
  3. promote the co-ordination of marine oil spill contingency plans and the action taken in response to marine oil spills under such plans.

The 2004 risk assessment base data-set has been improved through better data fidelity and data depiction undertaken for the oil pollution levy work by Russell Plume. Much of this data has been deduced from the 2004 risk assessment and improved to produce accurate depiction of the movement of oil in vessels around the NZ coast. This data has been incorporated into this current risk assessment.

Additional resources

2010 Summary Results

Interactive Map