Category:Hazard Assessment

Hazard assessment in case of a spill situation has different functions: When responding to a spill situation it is vital to know which hazards COULD present.

Also, for documentation reasons, it is helpful to be able to pin a number on the incident, indicating how severe it is. In oil spill statistics for instance; spill amount is used to indicate the severity of a spill. However, when dealing with HNS substances the severity is more dependent on the type of substance than on the amount spilled. The following paragraphs show a method of determining hazard scores for individual hazards as well as scoring the severity of an accident. These methods are based on the work of Koops. The gravity scale for accidental spills is intended to indicate the gravity of an accidental spill at sea. This tool describes the overall seriousness of the situation in the event of an accidental spill at sea. This tool is a kind of gravity degree meter for accidental spills. The tool results in a gravity scale value, between 0 and 12, which represents the seriousness of the accidental spill (a gravity scale value of 0 is an insignificant spill, and a gravity scale value of 12 is a very severe catastrophe). The procedure developed is a scoring system that can be used to compare the overall hazards arising from different accidental spills. Figure 7 shows the framework for obtaining a gravity scale for accidental spills value.

The scale is based on questions that can be answered in the first stage of an accidental spill: quantity spilled, substance(s), place of release. The quantity spilled may be the amount released or the amount, which could potentially enter the marine environment or even a combination of both.

For spills at sea three types of sea areas (open sea, vulnerable and populated area) are discerned by which the gravity of the accidental spill could be valued. The gravity scale for accidental spills does not predict the risk of exposure, the probability that consequences will ensue or the difficulty of clean-up. Hence the gravity scale for accidental spills only requires average conditions to be known or presented in these areas. It does not go into further details regarding wind-direction, the species in a certain area, the season, number of people and local situation that influence directly the adversity of the effects. To determine the gravity of an accidental spill for the coast or for inland waters would require more categories of areas in which a spill could take place.

In the procedure (see Figure 69) that determines the gravity of an accidental spill, the hazard quantity approach has been used. The threat posed by an accidental spill is, in this approach, assessed by using the product of amount spilled times a hazard indicator value. The selection and nomination of these hazard indicators (i.e indicative parameters representing a range of possible consequences of a spill) has been done by Koops. A panel of experts has done the weighting of the different hazard aspects. This more practical approach determines the hazard quantity(ies) of each relevant hazard in each compartment (air, water surface, water column, sea-floor).