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1.CHEM.E. SYMPOSIUM SERIES NO. 110

RISK MSESs)l[lPTr CASE STUDY - m STATE OF BAmAIn

L.G. ~acon*

The development of industrial activities in Bahrain has accelerated in recent years. In order to provide an overview of the potential risks. the Ministry of Development and Industry of the State of Bahrain codssioned a risk assessment of all industrial activities on the island. The study and the results are reviewed with emphasis on the selection of acceptability criteria.

The development of industrial activities in Bahrain has accelerated in recent years to include not only oil production and refining but also the use of readily available natural gas in energy intensive industries, euch as aluminium refining and in the manufacture of chemicals such as ammonia. In parallel with these activities, the port facilities have been developed for import of raw materials and export of products.

This industrial development has inevitably increased the handling and storage of flammable and toxic materials, with a resulting increase in the potential risk to the conmunity.

As a result of some major industrial accidents, particularly over the past few years. both industry and regulatory authorities in many countries have started to develop strategies to control the presence of risk generated by industrial activities. As part of this strategy it is essential to identify the relationship between the sources of risk (typically manufacturing. storage and transport of hazardous materials) and the receptors of the risk (typically residential populations).

In order to quantify the risks posed by their expanding industry. the Miatstry of Developnent and Industry of the State of Bahrain commissioned a study to:

o Identify all significant sources of industrial risk

o Quantify the risk in all such cases

o Suggest actions. if required, to reduce euch risk exposure.

* T e c M c a Ltd., London

643


The purpose of this paper is to present the details of the risk arressment. which was carried out in order to fullfil the above requirements. Particular emphasis is placed upon the development and use of criteria for the acceptability of risk, against which the results were compared.

The Scooe Of The Stud1

In carrying out the risk assessment, all industrial activites with the potential to cause fatalities in the conununity were considered. Such activities included the production of oil and natural gas, refining of these materiale, manufacture of chemicals, transport and storage of raw materials and products and the use of chlorine for dosing water supplies. The risks posed by these activities were only considered in the residential conrmunities beyond the boundary fences of the industrial areas. The risks to chemical industry workers while on site were specifically excluded from the study.

THE INDUSTRIAL ACTIVITIES CONSIDERED

The major process industries in Bahrain are either oil and gas related or concerned with metal refining or forming. These industries are located mainly on the east side and in the northern half of the island, as shown in Figure 1, with the major areas of population to the west and north of the industries. The metal industries and the petrochemical plant are recent developments. while oil and gas production and refining have been carried out for over 50 years. Each of the significant industrial installations, which were considered for analysis. are described briefly below.

Oil Industries

The Bahrain National Oil Campany (BAUOCO) is responsible for the exploration and production of oil and natural gas in Bahrain.

Bahrain Nation Gas Campmy (m) processes the associated gas from oil production. The LPG products are pumped to a large refrigerated storage installation at Sitra jetty and exported in LPG carriers.

The Bahrain Petrol- Ctnpany (BAPCO) refine crude oil from both local production and imports from Saudi Arabia. T*o large tank farms are associated with the refinery, one at the refinery itself and the other near the Sitra jetty. Six pressurised LPG Horten spheres are located within the refinery area.

Chemical Industry

Gulf Petrochdcal Industries Campany (GPIC) is the only large chemical operation in Bahrain. Anmonia and methanol are produced from natural *Khuffl gas feed. The plant is located on reclaimed land adjacent to the Sitra jetty. The products are exported by sea.

Public Utilities

The W s t r y of Works. Pcnrsr and Water is responsible for the production of electric power and public water supplier. Electricity is produced in four power stations using gas turbines running on natural gas. Water is purified at Sitra Power and Water Station and at the U s Abu


Jar fur series out at

reverse osmosis plant. The pure water is mixed with well water at a of blending stations in populated areas. Chlorine dosing is carried the plants and blending stations.

Marine O~erations

Shipment of ammonia and methanol from GPIC, propane and butane from BANAGAS and LPG and petroleum products from BAPCO takes place from the Sitra jetty.

Metal Industries

The main metal industry companies and the potentially hazardous materials used are:

Gulf Almhiufn Bolling Hill -y (-0) - Natural gas liquids separation facilities.

Aluminium Bahrain Campany (ALM) - LPG storage installation. A number of other similar industries were considered not to pose a

risk to the external populations.

Other Industries

Various other enterprises were considered to pose a potential risk to external populations and were therefore included in the risk assessment. They are:

Bahrain Aviation Fueling Ccmpany ( m 0 ) - Storage and pipeline for aviation kerosene.

Bramco - Transport and storage of quarry blasting materials. Bahrain Gas - Transport, storage and cylinder filling of LPG. Hader Gas - Transport, storage and cylinder filling of LPG. Prosperity Trading and Contracting Establishment - Transport and

storage of chlorine.

Yateem Oxygen - Storage of propane. (Other materials at this site do not pose significant offsite risk.)

A number of other companies were conaidered but were found not to pose a risk to offsite populations.

POPULATION AND METEOROLOGY

The areas of residential population in Bahrain are shown in Figure 2. The most densely populated areas are in the north east area of the country, at least 10h from the main industrial areas. The data used for the study were derived from census data for residential populations. Industrial populations were not considered since they were specifically excluded from the scope of the study.

The wind rose in Figure 3 shows that the prevailing wind is from the


north west thus tending to blow released material away from populated areas. The data used were supplied by the Bahrain Meteorological Service and were analysed to produce the probabilites of wind in twelve different directions in six categories of wind speed and atmospheric stablility.

The methodology which was used for this study is conmonly referred to as 'Classical Risk Aseesment' as described in Rijnmond Public Authority (1). The main features of this method are:

Identification of Failure Cases.

Data on the plant and its operation are used to derive a set of failure cases. These cases are chosen to be representative of the full spectrum of possible releases with the potential to cause fatalities beyond the site boundary.

Estimation of Freauencies

The frequencies of each of the failure cases are estimated from generic failure rate data for the various components involved.

Calculation of Coneeauences

The potentially fatal consequences of each failure case are calculated. Models for dispersion and toxic and flanunnble.effect8 are ueed to calculate the areas in which fatalities are expected for each of the different weather conditions. A probit equation is ueed to evaluate the toxic effects of chlorine and amonia.

Calculation of Risk

The fatal effect areas of all consequences of all failure cases are sunned to produce overall risk results. At this stage the distribution of population. the presence of ignition sources and the wind rose are all taken into account.

Presentation of Risk

The results of the study are presented as Risk Contours and F-N Curves. Risk Contours are used to show levels of individual risk. Contours are drawn at intervals of one decade and indicate the risk of fatality per year. F-N curves are used to express the community or societal risk. The curves show the frequency (F) with which a certain number (NI or more fatalities are expected to occur and they indicate how the frequency falls as the scale of incident increases.

RISK CRITERIA

In order to make use of the results of any risk aseeement study, it is necessary to have criteria against which the results may be judged. The form of these criteria must be similar to the form in which the risk analysis results are calculated. Risk results for this study are presented as risk contour plots and F-N curves.


The subject of the values which are used as risk criteria is by no means authoritatively established as world-wide or national standards. However, there are some levels which can be recognised as guidelines in interpreting the results of a risk analysis, because they are derived from consideration of various statistics relating to mortality of the individual or of groups. It should be noted that these criteria only provide guidance on the extent to which remedial action should be considered. Furthermore it is often difficult to apply such criteria in the context of current operations, as it is often not feasible to significantly change the level of risk without substantially modifying the source of the risk or relocating the subjects at risk. The economic implications of making such changes to existing plant may be much greater than for changes being made at the design stage of new plant.

Risk Criteria for Individual Risk

It is generally accepted that the level of risk regarded as acceptable for the general public should be less than that for employees. There are many arguements for this, one of which is that an employee accepts voluntarily the risk associated with working at a hazardous installation and people will usually accept a higher level of risk from voluntary activities than they would from an external activity or event over which they have no control. The risks from some voluntary and involuntary activities are listed by Lees (2). Involuntary risks may be regarded as being accepted where there is no significant outcry against them.

From these data, it is clear that people accept risks in excess of 1 0 - ~ per year for voluntary activities, and that involuntary risks are accepted provided the risk is sufficiently low. In this regard it can be argued that risks against which no general measures are taken (e.g. lightning conductors are not usually installed to protect the population) are acceptable. On the other hand general measures are taken against fires and road accidents.

In setting criteria for the acceptability of risk two levels are often used, as suggested by Lowe (3). Risks above the upper level are considered unacceptable and those below the lower level are considered acceptable. Risk levels which fall between the two may be considered acceptable if all reasonable measures have be taken to reduce the risk and the risk generator is of sufficient benefit to the connnunity. This use of two levels acknowledges the fact that there is some error in the calculation of absolute levels of risk and allows scope for 'reasonably practicable' judgements between intolerable and acceptable levels.

Ale (4) arrives at an individual risk criterion by suggesting that industrial activity should not increase the risk of death from natural causes of the most exposed individual by more than 1%. The lowest value for death by natural causes is for children between 10 and 15 years old and is 1x10'~ per person per year. Risk levels above 1x10'6 are therefore considered unacceptable. Following Lowe (3). he proposes a band of uncertainty with a level below which risk is totally acceptable, set at 1x10-~ per year.

The Environmental Protection Authority of Western Australia (5) have proposed two criteria for the acceptability of individual risk levels from new industrial installations. Levels of risk below 1x10'6 per year are - considered to be acceptable and levels above 1x10'~ per year are considered unacceptable. These are cumulative values including any adjacent hazardous industries.


In assessing the results of the Bahrain study Technica proposed the following criteria:

Action Level Individual risk of death of 1x10'~ per year.

An individual risk level greater than this is not acceptable and action should be taken to reduce the risk.

No Action L e v e l Individual risk of death of 1x10'~ per year.

Individual risks of lees than 1x10-~ per year are regarded as acceptable and no further action to reduce risks is required.

For risk levels of between 1x10-5 per year and 1x10'~ per year it is desirable to reduce the risk.

The criteria discussed above are shown in Figure 4.

Risk Criteria for Societal Risk

It is generally accepted that the public reaction to multiple casualty accidents is greater than it is to the same number of deaths occurring separately. For this reason societal risk is presented in the form of an F-N curve and criteria as limits on where this curve may lie. Societal risk criteria are usually applied to a particular community. That is the total risk from a11 industries which could affect the same population would be considered.

There have only been a few attempts to define societal risk criteria in this form, and a11 of those known to Technica are shown together in Figure 5. The pair of lines proposed by Ale (4) (G and H on Figure 5) as unacceptable and acceptable limits were put to the Netherlands Government to be adopted as criteria. However. the Government adjusted both lines down by one order of magnitude when the national criteria were set. In addition to the criteria shown in Figure 5. the HSE (6) have recently suggested that the tolerable level of risk for accidents from a single nuclear facility, which affect a large number of people is between 1 in 1000 and 1 in 5000 per annum (between 1x10-~ and 2 ~ 1 0 - ~ / ~ r ) .

In assessing the results of the Bahrain study, Technica proposed the lines suggested by Ale, as the societal risk criteria.

RESULTS

Individual Risk

The individual risk results for all industrial activities show that. in general, risk levels greater than 10'~l~ear do not occur in populated areas. The areas where the risk level is greater than 10'~l~ear are shown in Figure 6. The large continuous eone in the north eastern corner is dominated by the effects of the various incidents which could occur on the amonia ships, when loading at the Sitra jetty and on the first part of their route away from Bahrain. Although such incidents are expected to be


very infrequent, they have the potential ta affect a substantial area due to the large cargoes (up to 800m3 in a single tank) which muld be released. Figure 7 shows the situation without these risks from shipping. On this diagram the risks from various facilities can be identified. These include :

The oil pipeline from Saudi Arabia (risks due- to fires af tar leakage).

Various water purification plants (risk due to chlorine).

Fuel supply at various power stations.

The major industries in the Sitra area (i.e. BAPCO, GPIC, BANAGAS etorage, ALBA. GARMCO and Sitra Poorer Station).

The BANAGAS plant.

The various LPG lines from the gas plant and BAPCO refinery to Sitra jetty.

BRAMCO storage of explosive materials.

Traneportation of LPG from the BAPCO refinery to LPG bottling plants and the bottling plants themselves.

Transportation of one tonne chlorine cylinders from Mujarraq to a site near BAPCO, and storage of these cylindere.

Supply of fuel to the airport.

It can be seen that in general the areas with risk levels above 1 0 - ~ / ~ e a r are not highly populated. The main exceptions to this are the areas around the water purification plants, (some of which are in areas of dense population). the LPG bottling plants and the route used for transport of LPG.

Societal Risk

A sunnnary of the societal risk curves for all of the industries where societal risk was identified is shown in Figure 8. In this figure, the upper zone is the area where the risk is 'unnaceptable' and the central zone that where risk reduction is 'desirable'. These F-N curves show considerable variation in societal risk levels which are affected both by the type of industrial activity and the local density of population. Some show risks which are predominately relatively high frequency - low consequence (i.e. emall numbers of fatalities) such as the BANOCO Khuff gas lines (Curve 1). Others show risks which are dominated by very large evente (high numbers of fatalities) at low frequencies (e.g. Marine Operations - Curve 10).

From Figure 8 it can be seen that levels of risk which are above the 'acceptable' criterion are caused by the activities of the following companies and operations:

Marine Operations - Export of Amnonia by ship


Nader Gas - LPG bottling plant Bahrain Gas - LPG bottling plant Power and Water Affairs - Khuff Gas distribution BRAMCO - Transport of explosive materials G.P.I.C. - Ammonia plant and jetty loading lines.

Of these, the export of cmaaonia by ship and the bottling of LPG produce societal risk levels which are significantly above the 'acceptable' criterion.

CONCLUSIONS AND RECOMMENDATIONS

In general the results of the study showed that the levels of individual risk are high, as would be expected, around major plants, but these plants are located away from areas of residential population. As a result of this, the levels of societal risk among such populations are not high.

However, other activities which involve the handling of hazardous materials do take place in densely populated areas and, as a result, produce significant levels of societal risk in some instances. These activities include the use of chlorine in water purification stations and the bottling of LPG for domestic use. Such activities, which at first sight may not be associated with high risk levels, are comon in countries like Bahrain.

The use of chlorine is a particular example. At the time that the risk assessment study was begun. all water purification plants used one tonne cylinders of chlorine for dosing water. The storage of such quantities of a very toxic material in the centre of highly populated areas produced levels of societal risk well above the 'acceptable' criterion. During the study, these cylinders were replaced with 50kg cylinders in the purification stations which are located in populated areas.

The results of the risk analysis were used to determine priorities for taking such action with respect to reducing or controlling such risk. Taking all the facilities analysed in this study, it was possible to distinguish three broad bands of priority in relation to the absolute scale of risk and the comparisons with the various proposed criteria levels. In examining the results, three categories of action were identified:

Recammanded Action The risk level is sufficiently high that various courses of action should be evaluated in order to minimise these risks.

Desirable Action The risk level is relatively low and does not necessarily require that any action be taken, however some risk reduction measures would be desirable.


Possible Action The risk is not. in all respects, so low that it is negligible and therefore if there are straightforward measures that can be taken these should be considered.

In addition to providing reconmendations for action in this form , the results of the study can be used in the future by the Government of Bahrain in planning the locations of both industrial activities and areas for residential population.

In using the results of a risk assessment for planning, the most obvious result to consider is the level of individual risk at the location under consideration. This is due to the fact that individual risk is relatively easy to understand and criteria for acceptable levels can be derived from available data as used in this study. Societal risk is a much complex concept and may be difficult for governments to conmunicate to members of the public. It is also more difficult to set criteria for societal risk based on levels of risk which are acceptable in other areas.

However, the further information provided by the societal risk results is valuable and should be considered in decision making. This fact is clearly illustrated by the results for the export of ammonia by sea. The level of individual risk is below that which is considered unacceptable in all populated areas. but because the potential area of effect of a release is very large, the societal risk is well above the acceptable level (see curve 10 in Figure 8).

Governments, who have the responsibility to protect all residents from both small frequent accidents and large rare ones, therefore need to consider both individual and societal risk when making decisions. Contours of individual risk give a good indication about which areas of land may be available for residential development without exposing individuals to high risk levels. In addition societal risk curves can be used to determine the acceptable density of population in areas where individual risk levels are acceptable but which should not be used for high density housing. Such areas can then be used for other industry or activites which involve low population densities, such as farming.

REFERENCES

1. Rijnmond Public Authority. 1982 'A Risk Analysis of 6 Potentially Hazardous Industrial Objects in the Rijnmond Area - A Pilot Study", D. Reidel Pub. Co. Dordrecht. the Netherlands.

2. Lees, F.P.. 1980. 'Loss Prevention in the Process Industriesn, Butterororthe.

3. L m , D., 1980, Malor Incident Criteria, Paper 1. Session 5, Eurochem 80 Conference.

4. Ale, B.J.M., 1984, Risk Assessment and the Safety of the Public, presented at the joint US Environmental Protection AgencylNetherlands Directorate General on Risk Analysis, Washington.


5. Environmental Protection Authority, Western Australia, 1987, and Hazards of Industrial Developments on Residential Areas in Western Australia, Bulletin 278.

6. Health and Safety Executive. 1987 The tolerability of risk from nuclear Dower stations.

1.CHEM.E. SYMPOSIUM SERIES NO. 1 10

1. &M a. surwt ons 3. BAN- CQLPUSSOI

STATION 4. MNAOAS CM- I. BANffiA8 STOUDI 6. W C 0 W3INEP.Y 7. GAMCO (I. GPIC 9. JETTY TKE ~ ---

10. U A U N POVP STATIOI 11. NADER O M 12. PROSPEP.1IY 13. I I P M POWER STATIOI 14. R0 PLANT 15. SITRA P m STATION 16. SITlU TANIVAPX

Figure 1 Locations of Main Industries

Figure 2 Populated Areas in Bahrain

Figure 3 Wind Rose for Bahrain


Risk of Fatality Propored Western Proposed for (per year) by Ale Australia this Study

Figure 4 Criteria for Individual Risk

10-5-

10-6-

10-7-

10-8-

COMRNY 'X ' UNACCEPTABLE LIMIT

C O ~ P A N Y ' X ' ACCEPTABLE

Unacceptable

Acceptable

m n m Y 'I' TARGET

UK NUCLEAR INDUSTRY RISK TARGET l KINCHIN 19781

Unacceptable

Accep*.able

GRONINGEN IHOLlAMI UNUXEPPBLE LIMIT (PROVINCIAL€ WTERSTAAT GRONINGEN 19791

Unacceptable

Acceptable

GRONINGEN IWOCUNDI ACCEPTABLE LIMIT I PRWINCIALE WTERSTAAT GRONINGEN 19791

PROWSEO NATKII(LL CRITERIA UNXCEPTABLE WR IHOLUNOI

PROPOSED NATIONAL CIITERU ACCEPIAIILL u n l T IHOLUNOI

Figure 5 Criteria for Societal Risk

654


Figure 6 Individual Risk For a11 Activities

i .

Figure 7 Individual Risk Excluding Marine Operations

Figure 8 Societal Risk Levels

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