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Oil Spillage

Better safe than sorry…


By Michael Roldan

Duty Manager, Oil Spill Response Ltd Fort Lauderdale, Florida.
Tel: +1-954-983-9880


Assessing the risk of an oil spill is a good way to focus your business on staying out of trouble in each of its operations while being well prepared to respond if the worst happens.

Why assess risk. Assessing the level of risk associated with any operation that poses a threat of an accidental release of hydrocarbons into the environment is an important step in being able to recognize ways in which the threat can be eliminated, managed or mitigated for that operation.

Define risk. For prevention, preparedness and response activities, risk can be defined as the probability of an incident occurring multiplied by the resulting negative impact or consequences.

Probability refers to the likelihood of an incident occurring. It can be determined in general terms or mathematically, depending on the risk assessment context. Consequence measures the impact that the incident may have, which can utilize various environmental and social-economic data points.

Using the above measurements we arrive at the formula:

Risk = Probability (of the incident occurring) x Consequence (expected impacts resulting from the incident).

These two components of risk must be considered and addressed in order to lower their values and, in turn, achieve a level of risk that is As Low As Reasonably Practicable (ALARP).

For example, in order to lower the probability component of risk, one could implement a more stringent maintenance and inspection program, restrict transfers to daylight hours or prohibit dual simultaneous transfer operations. As these measures show, lessening the probability of an incident is done by eliminating operations that pose risks or by managing these operations so that the risk becomes ALARP.


To lessen the consequence component, one could bolster response capacities by improving oil spill response planning; by making sure that staff receive a high level of incident response training and have the opportunity to practice these skills during frequent exercises and drills; and by correctly managing the type and quantity of response resources available to the operation.

Lessening the consequence component, and thereby mitigating the effects of a spill, is called preparedness and forms a key part of a continuous process of improvement and assessment that runs throughout the operations lifecycle.

How to assess risk. To assess the risk of an operation, one can use a qualitative approach, a quantitative approach or a combination of the two.

In the quantitative approach, list the various activities that form parts of the operation, then detail the scenarios that could occur during each of these activities that could result in an oil spill incident.

For example, bunkering a vessel is the operation. Transfer operations from a fueling barge to the vessel using a flexible loading hose is the activity. A resulting scenario could be ‘spill caused by loading hose failure’ with spilt product type and quantity based upon hose volume, transfer pump capacity and flow rate assessed. Once all these scenarios are listed, score their risk based on a pre-established set of criteria for probability and consequence.

An alternative approach is the qualitative approach, which uses descriptive terms or ranges. The qualitative approach is more subjective and so must be clearly defined for it to be of any value. In the end, whether qualitative or quantitate, risk scoring produces an ordered or prioritized list of items that may need to be addressed.


Next steps. There is a wide-ranging suite of risk assessment tools available. You will need to do some research to determine which is best for your operation. One option to assess response plans in depth is to use ARPEL’s Readiness Evaluation Tool for Oil Spills (RETOS) – found at – which is popular throughout the Caribbean and Latin America.

Another option for a quick overall preparedness assessment is Oil Spill Response Ltd’s online risk assessment tool. It produces an individualized Action Report based on responses that the user can edit for specific needs and can be found at:

Whichever risk tool or methodology is used, it is always wise to remember that risk management is a continuous and iterative process and that its true value can be found when its results are faithfully addressed.

*ARPEL is a non-profit association gathering oil, gas and biofuels sector companies and institutions in Latin America and the Caribbean (

**Oil Spill Response Ltd is an international industry-funded cooperative which exists to respond to oil spills anywhere in the world by providing preparedness, response and intervention services (