Response: clean-up methodologies
in the event of an
oil spill
Its phases, organisation and the decision-making process.
Response
on the shoreline consists of a sequence of closely linked
operations, which must be made compatible:
- Measures taken before the pollution reaches the shore
- Site clean-up
- Worksite and waste management
Clean-up phases
In the case of heavy pollution, clean-up begins with phase
1, initial clean-up, operations, which are followed by phase
2, final clean-up operations.
Initial
clean-up (phase 1)
The aim of this first phase is to prioritise the removal
of accumulations of pollutant and various heavily polluted
materials (sediment, floating debris, seaweed etc.) as quickly
as possible.
The aim is two-fold:
- To limit the spreading of the pollution, by reducing the risk of the beached pollutant being reclaimed by the sea or moved by the wind
- To limit the ecological impact, by reducing the length of time the pollutant is in contact with the environment, and/or employing the least detrimental techniques.
Final
clean-up (phase 2)
Final clean-up is a response to the need to return sites
to their previous uses and to allow the affected environment
to resume normal ecological functioning. Final clean-up
should only begin once initial clean-up of large accumulations
of pollutant is complete, and once all threat of new significant
beachings has been eliminated.
It involves employing techniques, which may be more or less
advanced, to remove residual pollution which impedes either
the site’s economic use or leisure activities, or
the ecological function or landscape of the sites affected.
Choice of techniques
Every pollution incident is an individual case and there
is no single cure all solution. However, there are certain
fundamental clean-up principles which can be adapted according
to the situation and how it evolves. There is a multiplicity
of techniques available for response in each of the two
phases. They differ according to:
- the characteristics of the pollution (extent, scattered or concentrated character over space and time, nature of the pollutant and types of deposits)
- the characteristics of the site: its accessibility, exposure, the nature of the substrates, the presence of debris.
Due to similarities in terms of environmental sensitivity, methods of trapping pollutants and clean-up techniques which can be used, it is common to group together the different type of coasts under 3 main categories, according to the nature of the dominant substrate:
- sedimentary beaches (sand and stones)
- hard uniform surfaces (rocks, boulders…)
- intertidal areas colonised, or currently being colonised, by higher plants.
Organising response
Response coordinators must permanently have an overall view
of the situation and of the evolution of the pollutant,
the pollution, the sea and weather conditions and the clean-up
worksites. This allows them to (re)define response priorities
and to ensure that the techniques implemented are appropriate,
depending on the means available during the allocated time
period.
The quality of response depends on:
- the pre-planned organisation and its implementation
- the means available
- the people involved, at the different levels, from decision-making to hands on work
- the conditions of team work.
Intervention can cause more significant environmental damage than the presence of the oil itself. The impact of clean-up techniques should therefore be kept to a minimum (and above all be less significant than the impact of the oil itself).
On certain ecologically sensitive sites, it can sometimes be preferable to “do nothing” and to leave nature to do the clean-up work: this is the case for instance for light pollution on marshland. If, due to a wrong decision or poor assessment, a clean-up operation proves to be unsuited to the characteristics of the pollution or the site, this may lead to harmful effects for the environment. It is therefore important for worksites to be defined by technical and environmental experts.
Furthermore, in order to prevent the spreading of pollution on land and to reduce further damage to a minimum, certain precautions should be taken when implementing particular techniques and setting up worksites, storage sites, access ways and paths (in terms of choices and protection).
When to stop cleaning
The quality of clean-up required mainly depends on the ecological
sensitivity of the site and its socio-economic uses. These
two aspects, which dictate the priorities and the need for
clean-up, vary greatly according to the season.
There now exists a general consensus on the need, in the event of a spill, to question whether it is advisable to intervene, by assessing the advantages and disadvantages of each strategy and technique which may be available and considering natural clean-up as a potential technique.
In the case of a major to moderate pollution incident, the removal of floating and deposited pollutant should be prioritised, wherever technically and ecologically possible and economically acceptable, as it is liable to be reclaimed by the sea and therefore acts as a potential source of (re)contamination, representing a threat for the environment. It is in no way a case of aiming to remove all traces of oil, but rather of providing the local environment with favourable conditions in order for it to recover normal functioning in the long run, whilst allowing local socio-economic activities to resume. This means that some pollutant may remain after clean-up, but in such proportions that it will no longer interrupt the functioning or the rehabilitation of the biotope or the socio-economic uses of the site. A thorough knowledge of response techniques in terms of their efficiency and potential ecological impact (physical and biological) is essential.
Decision-making
Oil spill response should aim to conciliate ecological and
socio-economic imperatives, even if their interests often
prove to be divergent and sources of conflict. The different
participants should consequently accept the fact that optimal
response cannot be void of drawbacks.
Should
we clean? Should we stop cleaning? The answers to these
questions tend to vary from the polluter, to the insurer,
to the victims, to politicians, scientists, ecologists,
the media, the general public… It seems that the solution
most often depends on the different parties involved coming
to a consensus on what is, on the one hand, ecologically,
economically and politically acceptable in terms of pollution,
and what is, on the other hand, technically, financially
and ecologically feasible in terms of clean-up. This explains
the need to set up an organisational framework which takes
into consideration all the opinions and concerns of the
people and organisations affected by the spill, in particular
by:
- researching the best technology available
- setting up advisory, assessment and control commissions (technical, local and political)
- developing surveying, monitoring and control procedures.
Once the objectives and limitations of response have been established, the clean-up techniques been defined and accepted and responder safety guaranteed, clean-up operations can begin.