Emergency response process and methods
The 3 tiered approach
These tiers are provided for in the Maritime Transport Act 1994.
All Tier 1 sites and vessels are expected to provide an initial response to incidents on their sites. Tier 1 is site-specific and includes:
- most shore-based industries that have oil transfer sites
- offshore installations
- all vessels from which a spill of oil is possible.
Commercial ships are required to have a shipboard oil pollution emergency plan.
Regional councils (and those unitary authorities acting as regional councils) make up Tier 2. These agencies must maintain a regional marine oil spill contingency plan for their region. These councils respond to marine oil spills within their regions that exceed the clean-up capability of Tier 1.
Each regional council has a stock of the equipment needed to clean up oil spills within their regional boundaries and particularly within their ports. This is supplied by the Oil Pollution Fund and is overseen by Maritime New Zealand.
Maritime New Zealand provides regional councils with resources and training to support them in undertaking this role.
Maritime New Zealand assumes responsibility for managing the response when (due to size, cost, location, complexity or environmental impact), containing and cleaning up a marine oil spill exceeds the capacity of both Tier 1 and Tier 2 resources.
The response to any oil spill within the Exclusive Economic Zone (EEZ) and those that occur outside the EEZ and over the New Zealand continental shelf are also managed by Maritime New Zealand.
If a large marine oil spill occurs anywhere within New Zealand’s area of responsibility, and it is beyond New Zealand’s own resources to contain it and clean it up, Maritime New Zealand will seek international support to the Tier 3 response.
Once a Tier 3 oil spill event has been declared, and a National On Scene Commander appointed, Maritime New Zealand can requisition appropriate vessels in New Zealand to support a response. This includes, for example, large support vessels servicing off-shore oil and gas rigs.
New Zealand has in place arrangements to provide international support through the 1990 International Convention on Oil Spill Preparedness, Response and Co-operation.
Tier 3 response roles
For any Tier 3 marine oil spill, the Director of Maritime New Zealand appoints a National On-Scene Commander (NOSC) to lead the onsite response.
The National On-Scene Commander’s Incident Command Team provides on-site planning and operational and logistical capability to manage and clean up a large marine oil spill. This team advises the NOSC on areas like dispersants, wildlife, environment, iwi and community, legal and health and safety matters.
During a major shipping incident, the Director of Maritime New Zealand and the National On-Scene Commander are also supported by the Maritime Incident Response Team (MIRT). They provide legal, nautical, financial, administrative and technical advice.
All oil spill response is a balance between:
- removing the oil
- causing minimum harm to the environment
- safety issues and the available resources.
The main options that the Incident Command Team consider when dealing with an oil spill are given below.
Salvage and intervention
Avoiding a potential or imminent spill is the best outcome in oil spill response. This will prevent or minimise environmental effects, potentially reduce toxic or health impacts, and very likely lower the overall cost of the response.
The following actions can prevent the oil from spilling in the first place or contain an existing spill:
- salvage of a vessel or installation
- containment of the oil within its original structure (tank, bunker, pipeline, etc.)
- safe transfer of the oil to secondary containment (a barge or lightering vessel).
Salvage is not the role or responsibility of the response operation. However under the Maritime Transport Act 1994, the Director of Maritime New Zealand has wide powers however to intervene to protect marine interests from discharges of harmful substances during emergencies.
The Director can require the owners of a vessel or site, a ship's master or salvor, or the operator of a site or installation or pipeline to take actions to protect marine interests. The Director can also take direct action, with respect to the ship, structure or cargo.
Allow natural break up
If the spill is a good distance from shore and unlikely to cause damage to marine wildlife or the environment, the best response may be to allow the oil to disperse naturally. The ocean contains bacteria that break down the molecular structure of oil into less complex substances that are not hazardous. In this situation, the only actions taken may be to report the incident and then monitor the movement of the oil and its rate of dispersal.
Other vessels are used to churn up the water to assist in breaking up the oil. The oil is then left to disperse naturally.
Dispersants are chemicals that help remove oil from the sea surface by breaking oil slicks into small droplets. The small droplets are then dispersed and diluted into the underlying seawater by wave action where they are broken down by bacteria.
With some oil spills the first priority may be to contain the oil to limit the impact on the environment. Once contained the oil can be recovered and removed for disposal. A boom is the most common piece of equipment used to contain an oil spill.
Once the oil has been contained, work starts on recovering the oil from the water. Mechanical skimmers and/or sorbents are most commonly used for this task.
Shoreline clean up
In some cases it is not possible to prevent the oil reaching the shoreline. The oil spill response then focuses on minimising long term damage and clean up of the area affected.
The goal of any shoreline clean up is to clean only to the extent that will speed up the recovery and use of the area. In many cases intervention can do more harm than good and must be measured against allowing natural recovery.
A Shoreline Clean up Assessment Team undertakes detailed analysis of the affected area and identifies sensitive areas. They then prioritise areas according to a number of factors including ecological value, socio-economic value, recovery time and cultural significance.
Shoreline clean-up techniques
The situation may allow or dictate that one or a combination of any of the following actions provides the most effective response.
This is the use of high or low pressure cold or hot water to remove residual oil, e.g. stains, weathered crusts, or oil absorbed into sediments. This response is used when recovery time can be significantly reduced or where there are over-riding economic, amenity or wildlife concerns. Flushing might be used if absorbed oil is hindering recovery.
This is an option for exposed shores where wave action is sufficient to remove oil. It is particularly appropriate for remote beaches where there are no overriding considerations. It is also appropriate for more sheltered shores where other techniques would cause unacceptable damage to the environment.
This is suitable for thick layers of oil but care is taken to minimize the removal of sediments and any organisms living on or in them. Unfortunately many suction devices are heavy and cannot easily be carried over rough terrain.
Where oil contamination is extensive but has not penetrated deeply, graders can be used to skim off the surface layer of oiled sand. This is then collected using front-end loaders. Front-end loaders can be used alone but this may result in more sand being removed than necessary, which increases the disposal problem. Sediment removal is best justified when there are overriding short-term considerations, eg. the need to clean a fishing or tourist beach where activities of socio-economic importance need to continue.
This involves moving oily sediments lower down the shore where they are exposed to greater cleaning action by the waves, or moving buried oil to the surface for the same reason. This technique is most appropriate for badly oiled coarse sediments on relatively exposed shores, where wave action will eventually restore the normal shore profile.
Small areas of a spill where oil has not significantly penetrated the sediments can be cleared using rakes and spades. It is a useful technique for cleaning patchy oil, also in cases where use of machinery is limited because of access or because it would damage the beach structure.
This is the breaking down of oil by microorganisms. Repeated and slow-release applications of appropriate fertilisers appear in some cases to speed up oil biodegradation by enhancing the activity of naturally occurring microorganisms. This works best when the oil concentration in the sediment is very low.
Terminating the response
Responsibility for control of the response remains with the appropriate tier until the response is formally concluded.
Winding down the response involves:
- the recovery, cleaning and maintenance of equipment
- demobilisation of all personnel involved
- debriefing staff
- completion of all documentation associated with the spill including preparing a final report.
Other actions may continue for some time:
- gathering information to assist cost recovery
- investigation and/or review of the incident and the response (if required)
- monitoring the environmental impact of the oil spill, eg on wildlife and seafood toxicity.
Who pays for the response
Under the Maritime Transport Act 1994 the polluter pays all costs from an oil spill response and subsequent clean up. If the spiller cannot be identified, the cost of the response can be recovered from the Oil Pollution Fund.
The Director of Maritime New Zealand has the power to investigate any discharge or escape of a harmful substance that is in breach of the Maritime Transport Act 1994 or the Resource Management Act 1991. Following an investigation, the Director may decide to initiate a prosecution against those who are considered to be liable for the pollution incident.
The cost of a response will depend on many factors, such as the quantity and type of oil spilled, the weather conditions at the time of the spill and the area affected. Large spills a long way from shore can cost very little if they break up naturally. Relatively small spills in a coastal zone supporting fishing and tourism can however be very costly.