Buncefield: five years on

At the time of the Buncefield accident in December 2005, all fuel storage terminals - as now - were designed, operated and maintained to meet their individual requirements, including elements such as geographic location and how fuel is fed to the site.

Further, in addition to a basic process control system, the need for safety instrumented systems at these sites was, and still is, the subject of a formal risk assessment. This takes into account the potential impact and influencing factors of each site’s location and individual environment.

Buncefield taught us what can happen if a flammable vapour cloud is formed by the overfilling of a gasoline tank. With this information, risk assessments can now be reviewed and the need for safety-related, overfill protection systems re-evaluated.

The nature and formation of a flammable vapour cloud was unknown at the time of the incident and, therefore, not considered to be a risk. As a result, it was not included in risk assessments.

Buncefield also demonstrated the importance for industry and the Competent Authority (CA) to share good practice, thus providing invaluable guidance in the procedures and processes necessary to ensure the effective and safe management of fuel storage terminals.

Since the Buncefield incident, industry and the CA have worked together to “produce comprehensive guidance aimed at minimising the risk of a similar incident occurring in the future”.

This development process culminated in the publication of the Buncefield Standards Task Group (BSTG) report, in 2007, and the final Process Safety Leadership Group’s (PSLG) “Safety and environmental standards for fuel storage sites”, in December 2009, which updated and superseded the BSTG.

Of the 25 recommendations from the original Major Incident Investigation Board’s (MIIB) report on the design and operation of fuel storage sites:

• Nine are directly applicable to duty holders;
• Two provide supporting data to the Containment Policy, the implementation of which is separate from the PSLG and is managed through the Environment Agency (EA) and the Scottish Environmental Protection Agency (SEPA);
• The remaining 14 are applicable either to the CA themselves, or to the sector as a whole.

Although the BSTG and PSLG reports are important tools in documenting good practice, it is in their implementation that real improvements can be achieved within the sector.

Systematic assessment of safety integrity levels
The PSLG and BSTG reports provided the key guidance that enabled operators with the necessary tools to re-evaluate the need for safety-related, overfill protection systems - based on the knowledge learnt from the formation of the flammable vapour cloud at Buncefield. This task is now complete.

Industry - those companies represented by UKPIA (United Kingdom Petroleum Industry Association) and TSA (Tank Storage Association) - demonstrated their commitment to primary overfill protection by agreeing to install a minimum of Safety Integrity Level 1 (SIL1) systems for all in-scope tanks at fuel storage terminals. This commitment was made ahead of completing the safety integrity level assessments.

Primary containment and high-integrity systems
Early improvements to fuel-storage terminals included:

• Assessing tank capacities and ensuring that the normal operating level, overfill level and the level alarm systems between these two points are both sufficiently defined and set, taking into account the anticipated response times of operators;
• The installation of remotely operated shut-off valves (ROSOVs), ensuring rapid isolation of finished gasoline storage tanks;
• A review of procedures to ensure that fuel transfers - between sites and from ships - are sufficiently controlled, with each party understanding their roles and responsibilities, and the actions to take in an emergency.

Following these early improvements, and after the completion of the assessment of safety integrity levels, industry is now in the process of designing and installing the safety instrumented systems for overfill protection. For many terminals, these systems have already been installed and are operational.

Secondary and tertiary containment
Should failure of primary containment measures - essentially the storage tank - occur, reliance is placed on the bund surrounding the tank to contain the spill. Much work has been completed to ensure this integrity, including:

• Assessing the leak tightness of bunds, including, where necessary, improving bund walls and floors, and sealing gaps around penetrating pipework;
• Ensuring the integrity of concrete bund wall joints, including the installation of fireproof steel plates, where appropriate;
• Reviewing bund capacity and putting in place improvement plans. In some cases, this will require significant groundwork and remediation may be for a longer term.

Industry has also been working closely with the EA and SEPA in completing a score card (gap analysis) against the requirements of the Containment Policy. This provides guidance on secondary and tertiary containment measures. The application of this policy, together with the development of implementation plans to address any remedial actions that are required, is ongoing.

High-reliability organisations and leadership
Aspects relating to human factors have also been reviewed, most notably in the areas of defining roles and responsibilities, use of contractors and shift-working arrangements.

Trade association initiatives, such as UKPIA’s commitment to process safety, address the PSLG’s principles of process safety leadership. Also, the formation, in 2009, of the Process Safety Forum provides the mechanism for the sharing of high level data and initiatives with other sectors.

Sector-level process safety performance indicators are also in the process of being collected; for example, UKPIA members have adopted the Tier 1 and Tier 2 metrics from API RP 754, with the intention to publish key information for the sector in 2011.

In summary, implementation of all of the findings from the original 25 recommendations of the MIIB report on the design and operation of fuel storage sites is an ongoing and long term commitment for both industry and the CA.

It is important to understand the significant and very real progress that has already been made and is continuously being made. Industry fully supports this process and will continue to support it through to its conclusion.

The PSLG is continuing its work, monitoring progress in response to the Buncefield incident, and, where appropriate, resolving any technical issues that arise. The Chemical and Downstream Oil Industry Forum is also working to further improve process safety at fuel storage terminals through the development of guidelines based on sound science and good practice, in order to help all those in the sector.