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CDOIF
Chemical and Downstream Oil
Industries Forum
CDOIF is a collaborative venture formed to agree strategic areas for
joint industry / trade union / regulator action aimed at delivering health,
safety and environmental improvements with cross-sector benefits.
Supplement to Guideline – ‘Environmental Risk Tolerability for COMAH Establishments’
Complex Site Example v0.0
Page 25 of 35
assessed quantitatively using stochastic modelling tools. For this mitigation barrier it then becomes possible to assign a
mitigation factor which represents the likelihood of that barrier being successful in limiting the potential impact at the
receptor. This process may also identify secondary ‘events’ which will then require a more detailed assessment in their own
right; for example the failure of the bund wall as a result of an overfill event.
Figure 9
–
Illustrative Bow-Tie barrier assessments
The process of assessing mitigation measures for each of the events may be presented in a flow chart as illustrated in
Figure
10
. The intention here is to incorporate a range of mitigation measures for each event in a methodical way and taking into
account an increase in complexity as the assessment progresses. At the same time the degree and cost of assessment was kept
aligned with the resultant level of risk with only more detailed assessment being undertaken for those scenarios which were
identified as driving the risk and to a point at which the risk could be demonstrated to be at least TifALARP. The range of
mitigation steps and the order in which those should be assessed will vary between sites.