Author Section:

HID CI4A

Version No:

3

Target Audience:

HID CI 1-5 & HID HQ (Bands 0-4), HID SI (Bands 0-4), FOD SG Inspectors (Bands 1-3)

Purpose

The purpose of this SPC is to –

• provide ongoing inspection guidance on the location and design of occupied buildings at both lower and top tier COMAH sites;
• highlight the importance of ensuring that the national project (which finished in 2006) is completed at all the COMAH top tier sites to which it applied.

In all cases, operators need to assess the risks to people in occupied buildings on site from fire, explosion and toxic hazards, and, where necessary, identify measures to reduce those risks to as low as reasonably practicable (ALARP). A timebound action plan should be agreed where remedial measures will take time to implement.

Background

1 Between 1998 and 2006, HID CID carried out a national inspection project on the location and design of occupied buildings at top-tier COMAH sites following a series of incidents over the last 35 years involving fatalities to building occupants on site. These include Flixborough, UK (1974), Union Carbide Plant, Bhopal, India (1984), Hickson & Welsh, UK (1992), Phillips plant, Pasadena, USA (1992), and La Mede refinery, Total, France (1993).

2 The Advisory Committee on Major Hazards (ACMH) Reports (1976, 1979 and 1984) emphasised the importance of addressing the risks to occupied buildings in the wake of the Flixborough disaster. The continuing importance of the need to protect people in buildings has been reiterated by more recent events, most notably the explosion at the Texas City Refinery in March 2005, in which 15 people were killed and over 170 injured, many in temporary buildings.

Project Completion

3 Therefore, it is imperative that any outstanding actions from the national project are completed as a matter of priority AND any post-project actions followed through on in a timely way:

• Project Completion – where an
  • occupied buildings risk assessment has not yet been completed (Milestone 3), or
  • operator action plan is needed to implement any further necessary remedial measures, but has not been agreed with HSE(Milestone 4)

suitable steps should be taken to rectify this without delay;

• Post-Project Actions - where operators do have an agreed action plan, it is imperative that this is monitored to ensure any necessary remedial measures are properly implemented and their standard verified. A demonstration that risks to people in buildings on site are ALARP should must be made in the safety report.

4 Details of the progress made during the project can be found in an SLC to be issued shortly. A copy of the original project SPC is available on request from CI4a (VPN 523-5789).

Legal Requirements

5 In addition to duties under HSWA and the Management of Health and Safety At Work Regulations 1999, COMAH Regulation 4 requires operators to take all measures necessary to prevent major accidents and limit their consequences to persons and the environment; this implicitly includes the need to reduce the risks to building occupants to as low as is reasonably practicable (ALARP). A demonstration should be included in the safety report.

Industry Guidance

6 The Chemical Industries Association (CIA) booklet 'Guidance for the Location and Design of Occupied Buildings on Chemical Manufacturing Sites' (revised edition, 2003):

• identifies some relevant good practice;
• aims to protect people in occupied buildings from industrial chemical activities through the application of risk assessment and goal-setting principles, rather than prescriptive standards. In some instances operators may need to take remedial measures beyond those identified in the booklet to reduce the risks to people in buildings to ALARP;
• considers the special requirements for control rooms, to enable the safe shutdown of equipment or to otherwise respond to an emergency. Occupants of control rooms should be protected to the same standard as those in other buildings on site, and they should not be in imminent danger whilst taking emergency action. Additional consideration must also be given to the need for the continued functioning and integrity of safety critical control systems in the event of an incident;
• is not restricted to control rooms, and includes new, existing and temporary occupied buildings. All operators (including non-CIA members) should be encouraged to use the CIA guidance, but they may adopt other means to achieve the level of safety required, as long as the same standard is achieved;
• discusses risk screening, the setting of a screening figure for the likelihood of a hazardous event occurring, to establish situations where risks are sufficiently low that no further consideration need be given to that event. This approach has value in ensuring that effort is not wasted, but operators should present a clear demonstration of their approach, justifying the conclusions they have reached.

'Occupied Buildings'

7 Appendix 1 provides some guidance on the meaning of "buildings" and "occupancy", as the CIA guidance does not define these terms.

8 Appendix 2 lists useful guidance and reference documents.

Steps Required

The key steps required for addressing safety in occupied buildings are as follows:

1. Are there occupied buildings on site?
2. Operator needs occupied buildings risk assessment
3. Agree operator action plan if further risk reduction measures necessary
4. Monitor delivery of occupied buildings action plan
5. Verify standard of remedial measures implemented
6. Demonstrate risks in occupied buildings ALARP in COMAH safety report (TT sites)

Identifying Sites Where Occupied Buildings are an Issue

9 Safety in occupied buildings should be addressed at all top tier and lower tier COMAH sites for fire, explosion and airborne toxic hazards. Occupied buildings across a wide range of industrial chemical activities (including chemical manufacturing sites, storage, liquefied petroleum gas cylinder filling, mixing, blending or repackaging chemicals etc) should be considered. The scope of this guidance includes a wide range of buildings within the site boundary, including new, existing and temporary occupied buildings or workplaces (e.g. portakabins/huts). All persons present in these buildings routinely (site personnel) or temporarily (contractors, maintenance staff, visitors) should be considered, whether in the building containing the major accident hazard, or in other buildings where the hazard could have a bearing on the location and design of the building.

10 Safety in occupied buildings is not relevant at normally unmanned sites, those without occupied buildings, or where the major accident hazards relate solely to the environment. This guidance does not cover off-site occupied buildings.

11 In situations where employees are closely and constantly involved with a process, and there is little or no separation between the person and plant (e.g. certain batch and semi-batch operations), a greater emphasis may need to be placed on minimising risks through improved inherent process safety.

12 Appendix 3 contains a framework type letter setting out some key requirements the operator will need to address for occupied buildings. The suggested paragraphs can be adapted as necessary.

Occupied Buildings and COMAH Safety Report

13 For COMAH top tier sites, safety in occupied buildings should be addressed as an integral part of the safety report, its assessment process and demonstrations. The Occupied Buildings Risk Assessment (OBRA) should form part of the predictive information provided in the safety report. In many, if not most cases, the OBRA will indicate that further risk reduction measures are necessary to reduce the risks in occupied buildings to ALARP.

14 Where operators have an agreed action plan in place for implementing any further necessary remedial measures, a demonstration 'in principle' can be made in the safety report. Once those remedial measures have been implemented, the demonstration can be made ‘in practice’.

15 Where a safety report has not considered occupied buildings and is in an advanced stage of the assessment process, or assessment conclusions have already been reached, the issue should be addressed through inspection and a subsequent demonstration for safety in occupied buildings made through a revision to the safety report.

Occupied Buildings and COMAH MAPP

16 At lower-tier sites where there are risks to people in occupied buildings, this should be clearly identified in the Major Accident Prevention Policy (MAPP) document.

Guidance on Risk Assessment

Purpose and Methodology

17 An OBRA should identify any preventive and protective measures necessary to reduce risks to people in on-site buildings from chemical operations to ALARP, in line with the CIA guidance and HSE principles for making risk-based decisions. The Management of Health and Safety At Work Regulations 1999 - Approved Code of Practice (L21) provides guidance on general risk assessment. More specific guidance on methodologies can be found in "Location and Design of Occupied Buildings at Chemical Plants: Assessment Step By Step [173 KB] ". This paper should be framed within HID's broader approach to ALARP. A quantitative risk assessment (QRA - to predict numerical values of risk) is not always required, but any assessment will need to consider the extent, severity and likelihood of harm to people in occupied buildings.

18 Alternative assessment methods may be used, but should be justified by comparison with the legal standard required by the HSWA (SFAIRP) and COMAH (ALARP), and not the CIA guidance. This should lead to measures being taken which achieve the same standard as those derived from the CIA guidance.

19 The hierarchy of measures is:

Prevention Control Mitigation

Priority should be given to the identification of further measures preventing hazards and controlling risks (primary safeguards, e.g. for existing buildings - improvements to process control, or the movement of personnel), rather than the mitigation of residual risks (secondary safeguards, e.g. structural alterations to a building).

Procedural considerations for Risk Assessment

20 Where an OBRA is not already available, for example as part of the safety report, the operator should be asked to provide one for review prior to any visit. A sample-based approach of the OBRA may be used to determine whether the operator has adopted the right approach to assessing the risks across the board. This would involve the careful selection of specific occupied buildings (for example those most at risk) and processes (those presenting the greatest risks to occupied buildings). The implementation programme should include the necessary remedial measures across the whole establishment, and should seek to prioritise measures to address building occupants at greatest risk first, on a cost versus risk basis.

Timescales for Risk Assessment

21 Timescales for completion of risk assessments will vary, depending on the nature and scale of the processes and their risks, the age of the premises, the location and design of occupied buildings and the type of technical solutions sought. Interlocking/overlapping of risk contours on certain sites with several hazardous processes could create a significant work load, purely on the basis that several separate assessments would have to be factored into the overall risk analysis and solutions derived, increasing the complexity of the analysis involved.

22 An indicative guide of timescales for completion of an OBRA is:

• 3 to 6 months: straightforward, single establishments, for the preparation of an OBRA and identification of the measures required;
• 12 months: establishments with extensive/varied processes and inventories, large establishments or multi-establishment occupiers.

23 Extended timescales should not be the general rule, but should be considered where the operator presents a valid case, with a firm commitment from senior management to completing the task in clearly defined stages within an agreed timebound period. Full consideration should be given to taking enforcement action in cases where the operator does not provide an acceptable justification for not completing the assessment within a reasonable timescale (see paragraphs 29-30 below).

Retrospective Application of Measures

24 It may not be reasonably practicable to retrospectively apply to an existing plant, a measure that would be required to reduce risks ALARP for a new plant (even if that measure has become, in effect, good practice for every new plant). Whether or not the measure can be applied will depend on the site-specific circumstances, the risk levels, and whether the costs of the measure are grossly disproportionate to the value of the benefits accruing from its adoption.

Prescriptive HSWA Guidance Standards

25 Separation distances given in some HSE and other guidance as a means to comply with HSWA are normally prescriptive and seldom intended to protect those in the vicinity of a major accident from the consequences (usually intending to protect hazardous inventories from sources of ignition, thermal radiation from fires etc). Therefore, compliance with this type of guidance is a necessary minimum measure in respect of safety in occupied buildings, but may not be sufficient at major hazard sites.

Discipline Specialist Support

26 Discipline specialist advice and support should be sought where it is unclear whether a risk assessment is adequate, particularly where there is doubt about:

• the methodology applied;
• whether remedial measures are appropriate - have all measures been identified, or implemented properly, to reduce the risks to people in buildings to ALARP? (Process Safety);
• the ability of an existing, upgraded or planned new building to withstand the effects of fire or explosion (FOD SG Construction);
• the appropriate storage or use of toxic chemicals, or harmful health effects from combustion products or entrained materials during a fire (Occupational Hygiene);
• the manufacture and storage of explosive substances (Explosives Inspectorate).

27 Where possible, an early decision should be made on whether specialist support may be required and discussed with the relevant Discipline Specialist Inspector to allow for workload planning.

Planning and Implementing Remedial Measures

28 The operator should draw up a timebound action plan for implementing any necessary remedial measures, especially where remedial measures may take time to implement, and have it agreed by HSE. Some remedial measures may require programmes of work which are planned around suitable "windows" in the production or plant life cycle, particularly where they may involve risk reduction at source or process control improvements. These factors should be taken into account when agreeing timescales for implementation. Consideration should be given to enforcement action where timescales for the delivery of such measures are overshot, taking into account any relevant contributory or dependency factors.

29 Once an agreed action plan is in place, it should be monitored and the standard to which the operator implements any remedial measures verified. As noted earlier (paras 14 – 16 refer), operators for COMAH top tier sites will also need to make a demonstration for occupied buildings in their safety report.

Technical Considerations

Film on Windows

34 Retrofitting film to the windows of an existing occupied building is one of a number of means identified for reducing the effects of blast loading on windows. Film reduces the risk of the glass breaking into shards. However, it will only minimally increase the windows resistance to blast loading, thus affording a low level of protection. Whilst window film is cited in the CIA guidance booklet as a low cost measure, there is emerging evidence to suggest that this may not always prove the case and hence not be 'good value for money'.

35 API RP752 'Management of Hazards Associated with Location of Process Plant Buildings' (paragraph 3.3.4.2) states that both the glazing and its framing system need to be strengthened to increase resistance to overpressure, or the glazing/framing system designed such that it will fail in a manner which minimises laceration risks (e.g. using polycarbonate, tempered glass, or laminated glass with internal catch bars). The key point is that if film is applied to windows, structural analysis and other measures may also be necessary, such as replacement of existing window frames with those which have deeper rebates.

36 Protective film has to be fitted effectively to the whole of the glass surface, including that held in the rebate and by the glazing beads. It is recommended that rebates are a minimum of 25mm deep. If the film is only fitted to the visible part of the glazing, in the event of blast overpressure it will prevent annealed glass breaking into shards, but will not necessarily prevent the whole of the glass sheet shearing around the edge of the window frame and flying into the room in one piece, and wrapping itself around the first object it hits.

37 If the glazing is effectively strengthened, this increases the loading on the window frame and its fixing into the building structure, which may result in the frame and its fixings into the building needing to be strengthened. If the frame fixings are weaker than the glass with film, then the whole of the frame and glazing will be blown in. If the frame fixing matches the strength of the glass plus film, then the loading on the building structure will increase and whichever is the weakest will fail first. Any increased load on the building needs to be transferred to a structural element with sufficient strength.

38 Careful assessment (including factors such as the need for structural analysis, competent installation, the costs of rebating and other strengthening measures, etc.) should be carried out before deciding on the efficacy and feasibility of applying window film. The occupied buildings risk assessment (OBRA) should demonstrate that all other reasonably practicable measures have first been considered, and that the use of film on windows for reducing residual risks would achieve the required standard of protection. FOD SG Construction Specialist Inspectors can provide further advice on this issue.

Building Design Standards and Codes

39 HSL carried out an international literature review to identify suitable standards for the design of toxic gas refuges (TGRs), and for protection against fire and explosion. The review indicated that all existing guidance on TGR design, including the CIA's, concentrates on identifying broad design principles and appropriate performance standards rather than defining specific, prescriptive design details to meet those standards. The complexity of the interactions between people, buildings and fire, explosion and/or a release of toxic materials, is such that no single set of calculation procedures or prescriptive codes/measures can be applied to all types of buildings in all circumstances.

40 CI4a have a loan copy of 'Methods for the determination of possible damage to people and objects from releases of hazardous materials' CPR16E Green Book - by the Netherlands Committee for the Prevention of Disasters caused by Dangerous Substances (CPR), 1992. Chapter 6 covers 'Protection against toxic substances by remaining indoors'. It discusses ventilation rates and absorption, calculating concentrations indoors, density effects and the accuracy of models for determination of the indoors protection against toxic substances. This book, and the HSL report, is available on request from CI4a.

41 Some broadly relevant British Standards on smoke control and fire safety engineering principles to the design of buildings (including the spread of smoke and toxic gases) are listed in Appendix 2, along with contact details for other organisations which may be able to provide a list of engineering consultants with relevant competences for the design of TGRs.

Temporary Occupied Buildings

42 The BP Texas City refinery explosion and fire (March 2005) killed 15 and injured more than 170 people. The severity of the incident was increased by:

• the inappropriate siting of temporary occupied buildings on site, in and around which many people had congregated. There was a poor level of hazard awareness and understanding of process safety. BP’s safety management system failed to ensure –
• adequate identification and rigorous analysis of process hazards, notably in relation to processes other than normal operation. Nor did their Management of Change process consider the possibility of a significant release of hydrocarbons at the stack involved during non-routine operations;
• the timely implementation of external good engineering practices for the siting of occupied buildings (for both permanent and temporary occupied buildings).
• BP’s failure, once a process upset/emergency situation had been recognised, to:
  • sound an alarm, and
  • evacuate those at risk.

Recommendations arising from the subsequent investigation identify occupied buildings as one of three key focal topics. HSE needs to be able to demonstrate that it has systematically ensured the lessons learnt from Texas City are properly addressed. Chemical Industries Division are carrying out a national project (lead by Richard Potter) to ensure the lessons learned from BP Texas City are properly embedded, initially at all UK oil refineries, but ultimately across all UK major accident hazard industries.
Some guidance on temporary occupied buildings can be found in Appendix 5 of the CIA booklet and listed in the bibliography in Appendix 2.

Recording Occupied Buildings Work on COIN

43 Occupied buildings project templates are still available on COIN site records, but their completion is no longer mandatory. However, it remains very important to track progress, and to demonstrate the project has been properly closed out at all the sites to which it applied. Therefore, for sites where the project applied but had not been satisfactorily completed (to Milestone 4) by project close (March 2006), the keyword OBP-FIN should be added to any related inspection contact documents attached to COIN when it does reach Milestone 4.

Further Information

44 If further information is required, please contact HID CI4 (VPN 523-4359, 510-6226 or 523-5789).

Appendix 1 - Guidance on Interpretation of "Occupied Buildings"

Introduction

Determination of what is a building and its' level of occupancy are important in assessing the scope and complexity of this topic at any individual establishment. Both issues are considered below. In considering these issues it is important to note that any single specified definition of either is likely to lead to anomalies at some point. HSE uses risk as a measure of concern and priority, and it is quite possible that a low occupancy structure on a high-risk site presents a greater risk than a similar, but high occupancy, structure on a low-risk site. Hence the following guidance should be interpreted broadly in the context of the risks presented at the site, rather than solely on the buildings and the time spent in them alone. Consequently, rather than use a single definition of a building or absolute value of occupancy, it is suggested that these are used as guidelines in considering what structures operators should include in their assessment in the context of the risks at the site.

"Building"

The first step in an occupied buildings risk assessment (OBRA) is to identify buildings at risk. The CIA guidance does not define what a "building" is. The operator should set out the criteria for their definition of "building" in their OBRA. One suggested definition is that a building has a roof and 75% of the perimeter enclosed (Chevron Research & Technology Co., cited in Chemical Engineering Progress Sept. 1997). Any architectural structure fully or partially enclosing people should be reviewed for consideration as a building.

"Occupancy"

The second step is to identify which buildings are "occupied". The two key factors determining "occupancy" are

• the number of people in a building, and
• the duration of their presence.

Both are highly variable, making it difficult to define the term prescriptively. Operators therefore need to develop/define their own criteria for their OBRA.

The revised CIA booklet provides basic guidance on "occupancy", and gives one example of a simple criterion based on the presence of people for more than 2 hours in any 24-hour period. API RP752 'Management of hazards associated with location of process buildings' (American Petroleum Institute, 2003) gives further guidance in section 2.5. A loan copy of this booklet has been obtained by CI4 and is available on request.

Some other examples of occupancy rates might include any building where the total occupancy exceeds:

• 4 person hours a week (e.g. 1 person for 4 hours, 2 people for 2 hours, 4 people for 1 hour);
• 2 person-hours in a 24 hour period; the use of person-hours means that if 4 persons are present together in a building for half-an-hour, then the building is occupied.
• 2 people for more than 1 hour in a 24 hour period (takes explicit account of group risk, whereas the other two criteria do not necessarily).

As a broad guideline, a building should considered for inclusion in an OBRA where:

• occupation is more than transient (e.g. more than brief entry for checking plant gauges and the like);
• there is a work station or chair present, or other evidence of a building acting as a base, or to which workers routinely return and are 'static' for a period;
• there is "tidal" usage e.g. canteens, changing rooms, visitors centres.

The level of risk to which a building is exposed is also a factor informing how critical the rate of occupancy is, so the higher the level of risk, the more stringent and conservative the criteria for occupancy should be.

Extending the argument in the introduction, there may be an "equivalence of risk" between a building exposed to high risk but with low occupancy, and one exposed to relatively low risk with high occupancy. Likewise between a building occupied by large numbers of people for relatively short periods (e.g. a busy canteen at lunchtime) and one occupied by very few people for an extended period (e.g. one process operator at a work station for a whole shift).

The operator should consider the priority given in identifying and implementing remedial measures, addressing buildings presenting the greatest risks before those which are used relatively lightly.

Appendix 2 - Guidance, Standards and Consultancy Lists

DOCUMENT TITLE	DESCRIPTION/LOCATION
SPECIFIC GUIDANCE
CIA Guidance for the Location & Design of Occupied Buildings on Chemical Manufacturing Sites	Produced by Chemical Industries Association, Revised 2003 ISBN 1 85897 077 6
Location and Design of Occupied Buildings at Chemical Plants - Assessment Step by Step	Produced by Martin Goose, MSDU April 2000. There are two versions of this document. One is an internal instruction, and the other a technical paper published in the open scientific literature. The differences are minor and reflect the different readership.
Occupied Buildings Course Papers	Available from CI4, including overview of the CIA Guidance, Process Safety Considerations. Good Risk Assessment, Remedial Measures - Civil Engineering

CASE STUDIES
Flixborough (Nypro/ UK) Explosion (1/6/1974)	Major accidents involving occupied buildings on site. Level 3 Guidance for the Assessment of COMAH Safety Reports.
Bhopal - Union Carbide (3/12/1984)
Hickson and Welch Ltd – Castleford; Fire (22/9/1992)
Pasadena - Phillips 66 (23/10/1989)
Ammonium Nitrate Explosion - Toulouse (21/09/2001)
BP - Texas City Refinery (23/03/2005)

TECHNICAL GUIDANCE
Control Room Design	Level 3 Guidance for the Assessment of COMAH Safety Reports - Technical Measures Document - refers to codes, standards and best practice applicable to the design of control rooms, including the CIA guidance.
API RP 752 Management of hazards associated with location of process plant buildings	Summarised in Level 3 Guidance for the Assessment of COMAH Safety Reports. Widely applicable to onshore process plants; covers similar topics to those dealt with in the CIA guidance; provides a methodology for the assessment of the hazards associated with the location of occupied process plant buildings, but does not deal with the design and location of safe refuges from the effects of fires, explosions or toxic releases. The American Petroleum Institute (API) are currently updating API RP-752. Latest edition November 2003. Apply to Acquisitions Unit, Sheffield for access to a copy, (email: acquisitions infoservices)
API RP 753 Management of Hazards Associated with Location of Process Plant Portable Buildings	Following the Texas City incident (2005), the American Chemical Safety Board (CBS) asked the American Petroleum Institute (API) to develop new industry guidelines for the location of temporary occupied buildings. API RP-753 aims to minimise the presence of personnel - and the use of occupied portable buildings - in refinery process areas as well as providing guidance on the safe placement of portable buildings, and their design and construction, including: what types of portable or temporary buildings should be sited and where they should be sited the occupancy of portable buildings and their use by non-essential personnel appropriate analysis methods for siting portable buildings specific siting distances for vapour cloud explosion hazards fire and toxic hazards general risk reduction measures Published June 2007. Apply to Acquisitions Unit, Sheffield for access to a copy (email: acquisitions infoservices)
Methods for the determination of possible damage to people and objects from releases of hazardous materials	Published by Netherlands Committee for the Prevention of Disasters caused by Dangerous Substances, CPR16E Green Book 1992. Chapter 6 covers 'Protection against toxic substances by remaining indoors'.
Guidelines for Facility Siting and Layout	Published by the Center for Chemical Process Safety (CCPS), USA (2003). Siting and layout of process plants, including both new and expanding facilities, using recognised consequence models, assumptions and data. Comprehensive guidelines in selecting a site, recognising and assessing long-term risks, and the optimal lay out of equipment facilities needed within a site.

BRITISH STANDARDS (with some relevance to toxic gas refuges) British Standards can be browsed at http://www.bsi-global.com and electronic copies obtained from HSE Info Centres.
BS 476- BS 476-31.1:1983 BS 5588-4:1998 BS 5588-5:2004	Fire tests on building materials and structures - various Fire tests on building materials and structures. Measures air leakage through door and shutter assemblies under ambient temperature conditions as being representative of smoke penetration through doorsets and shutter assemblies occurring from the early stages or at a remote position from a fire occurring in a building. ISBN 0 580 13392 3 Fire precautions in the design, construction and use of buildings. Code of Practice for smoke control using pressure differentials. ISBN 0 580 26246 4. Fire Precautions in the Design, Construction and Use of Buildings. Code of Practice for Fire-fighting Stairs and Lifts. Includes smoke control. ISBN 0 580 43804 X
BS 7974:2001	Application of Fire Safety Engineering Principles to the Design of Buildings. Code of Practice. Framework document setting out philosophy for an engineering approach to the achievement of fire safety in buildings by giving recommendations and guidance on the application of scientific and engineering principles to the protection of people, and the environment from fire. Applies to design of new buildings and appraisal of existing buildings. 7 related Published Documents (PDs). ISBN 0 580 38447 0
PD 7974-0:2002	Guide to Design Framework and Fire Safety Engineering Procedures - Provides guidance on the use of BS 7974:2001 as a framework for an engineering approach to the achievement of fire safety in buildings ISBN 0 580 40169 3.
PD 7974-2:2002	Spread of Smoke and Toxic Gases Within and Beyond the Enclosures of Origin. Guidance on application of fire safety engineering principles for the treatment of smoke movement, control and management problems. Can be used to calculate the time between the detection of a fire to conditions developing which would be dangerous to building occupants. ISBN 0 580 40168 5.

ASSOCIATIONS & CONSULTANCY SERVICES
Building Research Establishment	BRE is a registered charity with a mission to champion excellence and innovation in the built environment. It is a centre of expertise on buildings, construction, energy, environment, fire and risk. BRE can provide research-based consultancy, testing and certification services to customers world-wide.
Institute of Chemical Engineers	IChemE is an international professional body, providing services for and representing the interests of individuals involved in chemical, biochemical and process engineering world-wide. It publishes a list of consultants and contractors who specialise in working for the chemical and process industries together with their areas of expertise.
Institution of Civil Engineers	ICE aims to advance the knowledge, practice and business of civil engineering, to promote the breadth and value of the civil engineer's global contribution to sustainable, economic growth, and ethical standards, and to include in membership all those involved in the profession. Established in 1818, ICE today represents over 70,000 professionally qualified civil engineers worldwide.
Association of Consulting Engineers	ACE represents the business interests of the consultancy and engineering industry in the UK. ACE has some 800 firms - large and small, operating across many different disciplines - as members.

Appendix 3 – Framework letter

Dear Sirs,

THE CONTROL OF MAJOR ACCIDENT HAZARDS REGULATIONS 1999
LOCATION & DESIGN OF OCCUPIED BUILDINGS
AT COMAH ESTABLISHMENTS

[Some suggested paragraphs which could be included in a letter]

Background

A number of major incidents over the last 35 years have caused several fatalities in occupied on-site buildings, including Flixborough, UK (1974), Hickson & Welsh, UK (1992), Phillips plant, Pasadena, USA (1992), La Mede refinery of Total, France (1993), Bhopal, India (1984), and more recently the BP Texas City explosion, USA (2005), which killed 15 and injured over 170 people.

Legal Requirements

The Control of Major Accident Hazards Regulations 1999 (COMAH), Regulation 4 require you, as the operator, to take all necessary measures to prevent major accidents and limit their consequences to people. This includes the safety of occupants in site buildings. A general requirement to take action on such matters is contained in the Health and Safety at Work etc. Act 1974, the duties of which are clarified in the Management of Health and Safety at Work Regulations 1999, Regulations 3, 4 and 5.

For top-tier sites, COMAH Regulation 7 places a duty on operators to demonstrate in their safety report that all necessary measures have been taken to prevent major accidents and to limit their consequences to people and the environment. This implicitly includes the need to make a safety report demonstration on safety in occupied buildings.

Guidance on Achieving Compliance

The Chemical Industries Association (CIA) has produced some guidance in consultation with HSE, entitled "Guidance for the location and design of occupied buildings on chemical manufacturing sites" (second edition, 2003), [ISBN 1 85897 077 6]. HSE consider this relevant good practice which should be used to facilitate compliance with your legal duties. The booklet can be purchased from the CIA, Kings Buildings, Smith Square, London, SW1P 3JJ.

ACTION REQUIRED

If you have not completed a risk assessment, you should do so now in order to identify the nature and extent to which occupants in buildings on site are exposed to major accident hazards from your industrial activities. You should

• identify which of these buildings meet an appropriate standard of design and location;
• identify any buildings which fail to meet an appropriate standard;
• identify any further measures which you will need to take to bring buildings up to a suitable standard; and
• demonstrate your compliance with the relevant legal requirements.

If the CIA guidance is used, you should identify which buildings are already located in accordance with the guidance. For those that are not, you should establish the margin by which they fail to meet the guidance and the action you plan to take. Such action could include outline proposals for a risk reduction programme, if your review shows this to be necessary. You should indicate estimated timescales envisaged for any remedial measures that are necessary. It would be helpful if the information could be provided in a table, using the following headings, together with a site plan showing occupied buildings, control room locations and toxic gas refuges, where required.

Building Name	Level of Hazard Protection		Action Required
	Required	Existing
Example only	300 mb overpressure	Sufficient only up to 200 mbar. Extensive glazed areas, concrete roof. See detailed report.	i) description of measures:...... ii) planned completion date: .......

Yours faithfully

 

HM INSPECTOR OF HEALTH AND SAFETY

cc [insert] Safety, Health and Environment Manager (etc)

• Appendix 4 – Exemplar improvement notice [PDF 124 KB]