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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.
6.2.1.1 Single substance stored in a single tank
Tank 1
Receptor
If we assume that credible scenarios, consequence levels of those scenarios and event
frequencies are as follows:
Scenario (Tank Farm Tank
1)
Consequence Level*
Event frequency*
Catastrophic tank failure
B
F1, 1x10
-6
Large hole
A
F2, 1x10
-5
Small leak from tank base
A
F3, 1x10
-4
*Provided for illustrative purposes only, and at this stage does not include mitigation. For
event frequencies refer to section ‘Determining unmitigated risk frequencies’ which is a
sub-section of 6.2. For consequence level, refer to ‘MATTE thresholds’, section 3.2.
The aggregated risk to the receptor for all credible scenarios can be calculated as
follows:
Category B incident frequency = F1 = 1x10
-6
Category A incident frequency = F1 + F2 + F3 = 1x10
-6
+ 1x10
-5
+ 1x10
-4
= 1.11x10
-4
Guideline – Environmental Risk Tolerability for COMAH Establishments v1.0
Page 36 of 88