Land-Use Planning
It is evident from past accidents in Europe and elsewhere that the consequences of industrial accidents can be severely aggravated because of the proximity of hazardous establishments to residential areas, transport hubs, commercial centres, public spaces and services. The devastating fireworks accident in the Dutch town of Enschede killed 22 people, injured over 900 and destroyed a significant part of the built environment of this town. A little over a year later, the explosion of an ammonium nitrate storage facility in Toulouse, France caused over 30 deaths, 10,000 injuries as well as significant property damage and psychological trauma to the surrounding population due to its close proximity to dense urban areas. With the aim of reducing the impacts from major chemical accidents, a legal requirement was introduced into the Seveso Directive in 1996 to encourage the establishment of appropriate safety distances between these areas and Seveso sites. The Directive does not provide detailed suggestions on how EU Member States should implement this requirement into their land-use planning policies. This approach reflects a conscientious application of the EU subsidiarity principle such that the Directive recognises that land-use planning is guided by historic and social values unique to each country. As a result, methods and criteria for applied to fulfil Seveso land-use planning obligations in the different Member States are quite diverse, even though they all aim to achieve the same objective, that is, to evaluate the potential consequences of possible major accidents for use in making land-use planning decisions. In particular, each country has established its own process for evaluating the risk associated with specific chemical accident hazards. Each applies a variation of the standard risk assessment approaches to incorporate the estimated risk into land-use planning decisions. Part of the process also includes, for some or all sites, depending on the country, an estimate of the risk associated with the hazardous site based on the analysis of consequences associated with a specific accident scenario or scenarios. Scenarios are selected based on information in the safety reports and site notifications. Calculation of risk estimates may be based on the data provided by the site or may be the regulator’s own standardized datasets.
Given the numerous possible inputs and the diversity of risk assessment and land-use protocols, the outcome of the land-use planning process for the same type of site can differ considerably from one country to the next. Much of this variation is difficult to avoid. It has long been acknowledged that risk methods and land-use planning processes are embedded in local culture and pre-existing legal systems. However, technical aspects associated with the consequence analysis, in particular, selection of scenarios and scenario attributes, are not subject to this constraint and yet they are distinctly different from country to country. Up until now, there has been no common accepted practice among Member States for determining which scenarios should be taken into account in the land use planning process. To address the issue, the Major Accident Hazards Bureau (MAHB) of the European Commission’s Joint Research Centre (JRC), together with the Land-Use Planning Task Force, a group of industry and competent authority experts from European Union (EU) Member States, produced this Handbook of Scenarios for Assessing Major Chemical Accident Risks. The availability of common reference scenarios allows the possibility for all authorities to consider the full range of possible outcomes when assessing risks associated with a major hazard site. Although it does not in any way ensure that authorities will arrive at similar risk figures or planning decisions, it gives a common framework in which the rules of science and logic can be applied. The use of common reference scenarios can, in particular, give citizens more confidence that authorities are ensuring that all necessary measures are being taken to reduce the impacts from serious chemical accidents.
Figure 1: Example - LUP zone map - UK approach (HSE)
Land-Use Planning and Risk Assessment
Land-use planning may be recognized as a tool for the reduction of potential impacts on vulnerable areas, thus mitigating consequences of natural hazards as well as man-made technical disasters. By regulating the development and control of land-use is a pro-active mechanism for reducing vulnerability. The "plan" is the anticipation of a desirable future situation and should be based on a proper decision - making process. This decision-making process may be regarded as a risk management - type structure, incorporating the usual elements of
- risk identification,
- risk analysis and
- risk evaluation.
Figure 2: LUP triangle of interdependence (Image courtesy of Lorenzo van Wijk)
ISO 31000:2009 and ISO 73:2009 define "risk management" as "coordinated activities direct and control an organization with regard to risk"; risk is defined as "the effect of uncertainty on objectives"[1]. This reflects the very different perceptions and understandings of the terms. Taking into account this fact it seems necessary to explain the role of risk assessment in the context of land-use planning.
Land-use planning decisions are a product of a number of considerations of central importance to local communities, such as sustainability, jobs, social services, tax revenues, and environment. p A land-use planning decision therefore is the result of an assessment of all the impacts that a proposed land-use will have on the community’s goals and objectives in these areas. For this reason, the chemical accident risk assessment is one part of the land-use planning process when a Seveso facility substances is involved. Other types of studies, such as environmental impact assessments, economic impact assessment, cost-benefit analysis, etc. may also contribute to the decision depending on the situation and what regulations apply.
The risk assessments typically conducted for land-use planning involving Seveso sites typically focus
- identifying, describing and evaluating scenarios, typically such of low likelihood of occurrence and potential high consequences and
- decide on limitations for the land-use as a result of the step before.
All forms of assessment of this kind comprise
- the identification of the hazard source, usually a technical site or an installation,
- the description of potential major accidents and their effects (not necessarily considering an exact likelihood),
- conclusions on the extent of the affected area and
- decision on necessary land-use policy action.
[1]Previous references on these definitions were more of technical nature; obviously the development in terminology standardization reflects the variety of the "risk management" fields of application
Land-Use Planning Accident Scenarios Handbook
The Handbook gives recommendations on possible major accident scenarios in the form of scenario trees. It is expected that the scenario recommendations will be useful to EU Member States and third countries who do not have a fixed LUP approach in place. A scenario tree is a taxonomy that shows the most relevant ways that an accident involving a certain dangerous substance may occur, using the structure of a bow-tie diagram. The scenario trees presented in the Handbook describe the dangerous substance and piece of equipment that may be involved in the accident, the critical event and the dangerous phenomena following the critical event. In the Handbook, five dangerous substances and four pieces of equipment have been identified and developed as scenario trees. These trees contain the main qualitative information with regards to potential sequences of events following a release. They can be used for land-use planning decisions or for emergency planning. The Handbook also offers a list of possible causes and safety barriers for the scenario trees studied. Therefore, quantitative information and data can be added to the qualitative description of the scenarios in order to make them quantifiable.
The Handbook proposes basic sets of scenarios and data input options to support consistent and transparent decision-making in land-use planning decisions associated with implementation of the Seveso Directive (2012/18/EU). This information is primarily aimed to assist EU Member States and other Seveso implementing countries in land-use planning, especially those that do have not consolidated a systematic approach of scenarios and criteria for assessing land-use planning cases in compliance with the requirements of the Seveso Directive. In addition, it is also possible to use the scenarios for emergency planning, provided outcomes are interpreted to conform with criteria appropriate for emergency response applications.
Structure of the Handbook
The Handbook begins with a general chapter that explains its overall purpose and scope, and, in particular, the importance of the accident scenario in risk assessment for chemical accident prevention and preparedness. The subsequent seven chapters provide common reference scenarios for each of 6 types of dangerous substances commonly used throughout the European Union (EU). The final chapter describes a benchmarking exercise in which eight different teams of experts from regional and national authorities of the EU conduct risk assessments for land-use planning on two fictitious sites using the common reference scenarios in this handbook.
Abstract
This report presents the collective work of the European Working Group on Land-Use Planning and discusses the activities towards more consistent land-use planning decisions through more understandable risk assessment approaches and data. The purpose of this book is to assist the EU Member States, especially those which do not have a consolidated system of approach, scenarios and criteria to assess the Land-Use Planning cases, in complying with the requirements of the Seveso Directive.
Figure3: Example of a LUP scenario tree - LPG storage tank
Handbook of Scenarios for Assessing Major Chemical Accident Risks:
Handbook of Scenarios for Assessing Major Chemical Accident Risks (print)
Handbook of Scenarios for Assessing Major Chemical Accident Risks (online)
