127 In paragraph 88 we set out consistency of assessment of risk as our guiding principle. To achieve it we have identified a number of relevant issues and made recommendations. Overall it moves in the direction of a more individualised approach to sites to identify the risks they present in a way that is more closely related to actual circumstances.
128 We say above that we expect work to begin on revising the land use planning system without delay and in parallel with the wide review called for in
Recommendation 1. We do recognise and commend the work done so far by HSE in responding to the land use planning issues raised at Buncefield though more needs to be done. We also recognise that the frequency data for vapour cloud formation and ignition and over-pressure propagation in open flammable clouds are uncertain. For the present, until the explosion mechanism work yields results, the uncertainties can be managed in the same way that they are currently managed, eg by using statistical outliers, sensitivity analyses and conservative assumptions in the event frequency data. Sensitivity analysis uses a range of failure event frequency data to test the assumptions behind the ones used in the risk calculations.
129 The explosion mechanism of the hazard of open flammable cloud explosions is only one new aspect to be incorporated in future revisions of the scenarios that feed the risk assesments. Revisions to all the scenarios that feed risk assessments need to be undertaken. In addition the new consultation distances applied by HSE to flammable storage sites are only applied to new developments. The impact of the Buncefield incident on the risks at and around existing sites needs to be viewed afresh. In the covering note to CD212(ref 3)HSE suggested there are already some
sites to which HSE could give priority treatment as the current system is overhauled and agreed methodologies for new risk assessment approaches developed. The Competent Authority will need to agree with COMAH operators and planning authorities a programme of reviews of the sites of greatest concern, with clear timescales against which progress can be measured and reported.
130 Account should also be taken of the impact of the measures that we call on in our reports to the risks of a major incident as we believe the risks will reduce significantly as the improved controls are applied.
131 We also expect the ALARP23(risks ‘as low as reasonably practicable’) risk
threshold to change as a result of what we learn from Buncefield. In other words, measures that would perhaps have been deemed unreasonable in terms of the cost of achieving a risk reduction may come into the scope of the ALARP condition in the light of a revision to the worst-case scenarios after Buncefield, accounting for open flammable cloud explosions and multi-tank fires. This needs to be considered for the major hazards sector as a whole. It is not uncommon for operators with duties under safety and environmental legislation to see the risk threshold under the ALARP principle as a ceiling, the point at which they may safely stop seeking further improvements. In fact the ALARP threshold is the floor on which dutyholders need to stand, the starting point for best practice that is rightly expected by the public and those who might be affected by the major hazard risks created by the site.
Recommendation 18 The Competent Authority should agree a priority programme
with site operators and planning authorities for assessing societal risk at sites of identified concern using the risk assessment methodologies developed in line with our recommendations. Account should also be taken whether the ALARP threshold has been raised due to considering previously unaccounted hazard scenarios.
132 Input to planning around major hazard sites under the system that we favour will be wider than from HSE alone. Quite apart from the critical new role for planning authorities and operators, guidance needs to be developed on how to use the criteria relating to risk contours, and societal risk indicative criteria when an acceptable approach and methodology for using societal risk have been devised. The Competent Authority will need to set the standard for what to do and for the criteria, while leaving the decisions to those affected. This is not a case of the regulator standing back from difficult situations. The Competent Authority will determine what needs to be provided – and by whom – to operate the system. The Competent Authority will also check that the system is operating as intended. 133 The Competent Authority will also have to decide how it will react, within its statutory role, to societal risk anomalies that come to light in the application of the revised system and there may well be lessons in how the French, Belgians and Dutch have adapted their systems to compensate for unacceptable societal and
environmental risk at existing installations in the light of applying new knowledge or invention.
134 What are the potential downsides of our preferred system? A risk-based approach is unlikely to significantly reduce the planning contours without the improvements to the control measures we call for being carried out in practice. For example, under the method adopted for the analysis that produced a model of a risk-based planning system (see Annex 10) it was shown that the Northgate Building was a significant contributor to societal risk at Buncefield. Modelling the Northgate building so as to be further away from the site showed how the societal risk could be lowered. In reality, under a risk-based system, it might be practicable to reduce societal risk by improving the risk control measures (on- or off-site, or both).
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23 The ALARP principle is further explained in Annex 5 (in the section ‘QRA applications of relevance to land use planning around major hazard sites’).
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Figure 12 A view of the
smoke plume at the height of the Buncefield fire as seen by police maintaining the cordon in the Leverstock Green area of Hemel Hempstead. Leverstock Green is one of the nearest residential areas to the Buncefield depot and many people were evacuated 135 A key disadvantage will be in the period of transition to a revised system
which will have significant implications for central and regional government and industry. To illustrate the difficult questions to be faced, eg on retrospection and interim application (with, as yet, incomplete tools), one need only look at
Recommendation 3, which calls for a broad economic case ‘including costs to the industry and wider society’ to be factored in. These will take some time and intellectual effort to determine, and the obvious question will be ‘what do we do in the meantime, or do we wait?’ On the subject of retrospection (which we have referred to, eg in paragraphs 29–30 and 126) we wish to make it clear that we are not calling for the bulldozing of swathes of perimeter developments or
decommissioning of major hazard sites. We are looking for the Competent Authority, COMAH operators and planning authorities to agree what are the priorities for action when factoring in societal risk, and to make targeted and proportionate responses and maintain public confidence.
136 Recommendation 13, which calls for reforms to the management of the decision-making process, illustrates the same issue. Some two and a half years after Buncefield progress now lies in confronting the difficulties and not being deterred by them. While we have addressed the questions of the scope of application, the pace of progress and what to do during an interim phase of several years, we will greatly value the commitment now of CLG and relevant ministers of the devolved administrations, and HSE in particular to press ahead on a number of fronts in the interests of balancing the necessary pace of progress with technical and resourcing factors.
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