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Health and Safety
Executive
Case study: WOSL
Page 2 of 6
Guidelines for Competency Management Systems for Downstream and Petroleum
Sites
(COGENT (2011)) is based on six principles that are contained within the CMS
cycle (see Figure 1).
Figure 1
The six principles of competence assurance
This cycle is underpinned by the management principles of ‘POPMAR’ (HSG65)
and is similar to the CMS cycle published by HSE in 2002 and by the Office of Rail
Regulation in 2007.
WOSL and ERM began by defining the scope of the CMS in line with COGENT
guidance (2011). As part of this process, and based on experience and industry
wide statistics, a team of subject matter experts decided on the safety critical tasks
at WOSL. Over 20 safety critical tasks were identified (eg permit to work), together
with related sub-tasks (eg completion and checking of work permits).
Major accident hazard scenarios were identified and plotted on a hazard identification
and risk assessment matrix (ie based on the severity and likelihood of the scenario).
The aim of this exercise was to prioritise the scenarios. Each scenario was presented
as a bow tie diagram (ie a diagrammatic representation of hazardous events including
threats, barriers and consequences). This helped to visualise the possible threats
leading to the scenario, determine the subsequent consequences of the scenario and
the potential barriers (eg control measures and mitigation factors).
In order to systematically consider the types of human failure that may occur when
performing the safety critical tasks, ERM and WOSL carried out a human error
analysis for each task, whereby each step of each task was assessed to determine
the potential human failure and/or the opportunity to recover from this failure. In
line with HSE’s Human Factors Roadmap, the human error analysis also formed