Peer review of the Atkins risk assessment for the proposed Chivas Brothers visitor centre adjacent to the Kennington Gasholders.
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Renaissance Risk
Safety in Numbers
Peer review of the Atkins risk assessment for the
proposed Chivas Brothers visitor centre adjacent to the
Kennington Gasholders.
A report by Renaissance Risk prepared for
London Borough of Lambeth
January 16, 2012
Renaissance Risk is a trading name of Renaissance Experts Limited, a company registered in England & Wales.
Company No. 6390351, Registered address: 30 Upper Park Road, Camberley, Surrey GU15 2EQ
PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012 Document Issue Control Sheet London Borough of Lambeth Peer review of Atkins risk assessments for the Chivas Brothers superstore, New Park Roundabout Document Number - 11/01009/FUL/RR1 Issue Date Author Checked Purpose 1 16 January, 2012 SMA Draft Notice “This report has been produced by Renaissance Risk for the London Borough of Lambeth for the specific purpose of being a review of the Atkins risk assessments for the “Beefeater Distillery” development and is only suitable for use in connection therewith. The report may not be used by any other party or for any other purpose without Renaissance Risk's express written permission. Renaissance Risk accepts no responsibility or liability for any unauthorised use or reliance upon any of the contents of this report.”
PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
Table of Contents
1. Summary .........................................................................................................................................1
2. Introduction & Understanding ..................................................................................................... 3
3. PADHI overview ............................................................................................................................ 4
4. Atkins risk assessment 5090979: Land Use Planning Assessment............................................. 5
4.1. The Atkins gasholder risk assessment................................................................................. 5
4.2. What is the risk? .................................................................................................................... 7
4.3. HSE call-in policy (in further detail) ..................................................................................... 8
4.4. Implications......................................................................................................................... 10
4.5. Conclusions .......................................................................................................................... 12PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
1. Summary
A planning application is to be submitted to the London Borough of Lambeth by Chivas
Brothers for a proposed change of use at their Beefeater Distillery at the Kennington site. The
proposal is for use of part of their building as a museum / visitor centre which is open to the
general public.
The site falls within HSE’s Consultation Zones of the nearby Kennington gasholder station.
The output of HSE's codified methodology for considering risk in Land Use Planning is PADHI.
The PADHI output for this proposed application is “Advise Against”.
Since HSE would advise against the proposed change of use, the Local Planning Authority
needs to have a full understanding of the nature and the quantum of the risks so that these
can be set in context alongside more familiar planning issues in the decision-making process.
Chivas Brothers has therefore commissioned a risk assessment report from Atkins in order to
provide the planning committee of the LPA with further information on the risks at the
proposed development.
The LPA has requested Renaissance Risk to undertake an independent review of the Atkins
report and to prepare a statement of opinion on the report's accuracy and veracity.
This document is an addendum to that statement and contains further detail which may be of
interest to the LPA and of value in the process of decision-making.
Gasholders have a high degree of inherent “safety”. From the implementation of the
Factories Act of 1961 to the current day, there have been no fatalities in the UK which have
been caused as a direct result of an event initiating at a gasholder.
This is also confirmed by information used by the HSE in developing their zone calculation
methodology, which indicated that there have been no fatalities at gasholder sites in the UK
for around 100 years [Ilkeston 19121].
More recently, the implementation of regulations to reduce major hazards, such as COMAH,
DSEAR, and the like, has further ensured that residual risk has been reduced As Low As
Reasonably Practicable (ALARP).
This does not mean, however, that major events at gasholders cannot occur; there are
several well-documented accidents in the UK which have caused property damage and injury,
and certainly gasholder accidents overseas have caused significant numbers of fatalities to
people in housing located very close to the gasholder.
As development close to gasholders intensifies in the UK it is important to ensure that the
safety aspects are fully considered.
1
A fatality caused by the drowning of an individual sheltering in a basement of a house during a gasholder fire,
and who was drowned when the gasholder water reservoir lost containment.
1PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
Although there is no evidence that the Kennington gasholders are unsafe, it is incumbent on
the developer to demonstrate, first, that the proposed development does not substantially
increase the residual risk and, secondly, provide the LPA with sufficient information to allow
the safety issues to be balanced against the socio-economic benefits.
Additionally, whilst it is almost certain that the risks at the proposed development would be
“acceptable” by UK standards, it is possible - though unlikely based on our understanding of
the scale and type of development proposal - that the HSE could “call-in” a decision by the
Local Planning Authority to grant this application. The introduction of additional people
working and shopping within the hazard range of the Gasholders does increase residual risk
and change the ALARP balance.
A high quality risk assessment is therefore essential to support decision-making on the basis
of safety for this development; the Risk Assessment by Atkins is, in our opinion, fit for this
purpose.
2PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
2. Introduction & Understanding
London Borough of Lambeth (LBL) has received a planning application for a change of use
development by Chivas Brothers at their Beefeater Distillery at the Kennington site. The
proposal is for use of part of their building as a museum / visitor centre which is open to the
general public.
The site falls within HSE’s Consultation Zones of the nearby Kennington gasholder station.
The output of HSE's codified methodology for considering risk in Land Use Planning is PADHI.
The PADHI output for this proposed application is “Advise Against”.
The HSE “Advise Against” is, as it states, advisory. It is for the LPA to ascertain the balance of
the increase in residual risk being from the proposed development against the societal and
economic benefits which would be derived from approving the planning application.
As part of the process of understanding the nature and quantum of the risks, London
Borough of Lambeth has engaged Renaissance Risk to undertake a peer review of the Atkins
Risk Assessment.
The document supplied by the applicant, which LBL has passed to Renaissance Risk for
review is shown in table 2.1.
Table 2.1 Documentation
Document Title Reference (date)
Land Use Planning Assessment of a Development at 5090979 / Technical Note 2
Beefeater Distillery, London (March 2011)
The specific site and the defined project boundary is shown in Figure 1, below.
Figure 1 - the proposed development site (bounded red) and consultation zones
3PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
One of the difficulties in using PADHI is that the assessments are black & white; there is no
room for the consideration of site-specific reduction in risk due to (for example) improved
risk mitigation and protection of population groups.
However, the HSE does recognise that the nature of their assessment of risk could lead to
developments which have well-defined economic and social benefit being rejected on the
basis of generic risk assumptions.
During the Brit Oval inquiry, the HSE stated that the correct approach on safety issues for
LPAs “is to consider the result of the PADHI assessment. If that result is an ‘Advise Against’ they
are to give that advice the most careful consideration in their LUP decision-making and weigh it
against the benefits of a planning application. Of course if they consider that (HSE) advice is
over-cautious they can of course seek so to demonstrate through suitably qualified expert
evidence.”
Whilst not of direct relevance, it may be of interest to London Borough of Lambeth to know
that the Institute of Gas Engineers and Managers publication (IGE/SR/4) provides safety
recommendations in relation to developments around gas holder sites. This publication,
which remains current, sets a distance of 18 metres within which buildings would not
normally be allowed on the basis that gas released from minor leaks on gasholder seals could
be drawn into any building within this distance and reach an ignition source. This rule of
thumb is based upon calculation of the dispersion of gas from typical seal leaks in a range of
typical wind speeds. This hazard has been considered by Atkins, but not in significant detail.
It is also relevant to note that The Greater London Authority planning report (PDU/Legislation
& Regulation/MM July 2007) stated that “The HSE PADHI system is a useful tool for determining
likely risks, however it can be determined that the current consultation zones proposed for
hazardous sites may be too inflexible, resulting in advice from the HSE that is too rigid and not
site specific. Where the HSE is minded to ‘Advise Against’ a development, the applicant should
be requested to provide a more detailed site assessment that would allow for detailed site
specific consideration by the HSE and ultimately the Planning Authority.”
The Applicant has therefore commissioned a Risk Assessment from Atkins which allows for
site specific consideration to be taken into account. Although there are some elements
within these Atkins reports which would benefit from clarification, we have reasonable
confidence in expressing our opinion that they are substantially truthful.
3. PADHI overview
The HSE set the PADHI planning zones around Gasholders using a specific event; a decoupled
seal resulting in a fireball involving 50% of maximum contents. The basis for this is a recent
HSE review of gasholder accident statistics. This review identified a few apparent large
ignited events and used these to propose that such events were credible enough to form the
basis of the Land Use Planning Zones. Therefore, until relatively recently, Gasholder LUP
Zones were of a much smaller radius.
However no incidents have been identified by HSE which could reasonably be shown to
behave with the damage consequences postulated by HSE.
4PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
It should be noted that HSE's assessment does not constitute a complete risk assessment. In
order to do so, it would have to include a number of lesser events which have higher
frequencies, but shorter hazard ranges. Whilst this does not affect the planning zones, the
inclusion of such events is relevant to the risk at locations close to Gasholders.
In short, therefore, it should be emphasised that the HSE assessment is primarily a screening
tool which allows codified and consistent responses to be made to individual planning cases.
Thus HSE only provide planning consultation to Local Authorities, and do not provide
prescriptive advice.
The PADHI system for Gas Holders uses the protection concept and Dangerous Dose, which is
sometimes taken to represent a probability of fatality of around 1% for an average population,
but is generally taken to correspond to a level of harm which would cause:
v Severe distress to almost everyone, or;
v A substantial fraction of the exposed population needing medical attention, or;
v Some people to be seriously injured, requiring prolonged treatment, or;
v Any highly susceptible people possibly being killed.
4. Atkins risk assessment 5090979: Land Use Planning Assessment
4.1. The Atkins gasholder risk assessment
Our review has considered the Atkins report ‘Land Use Planning Assessment of a
Development adjacent to the Kennington Gas Holder’ dated March 2011. We have also
undertaken a limited amount of independent research. We have not reviewed the
proposed application.
Our working assumption is that it is not possible to reduce the floor area of the
exhibition hall to below 250m2. Such a change would, however, reduce the Sensitivity
Level such that PADHI would be expected to return a DAA result.
Our understanding from the Atkins report is that the proposed development is of PADHI
Development Type DT 2.4. From the building area given in the report Atkins derive
PADHI sensitivity level SL2.
We agree with both of these findings based on the information in the Atkins report;
however we do consider that part of the development could be considered as a
Development Type 1.1 - Workplaces. Whilst this does not materially impact the PADHI
process, it is important to recognise that some of the people present are employees and
not the public.
The development site is within the Inner Zones of two gasholders and is classified as
being within that zone. For the purposes of PADHI assessment, any car parking and
landscaping associated with a development is not assessed independently to the
building; the building is assessed on its own merits and the car park and landscaping
adopts this PADHI decision.
5PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
Figure 2: Planning Application Drawing - proposed exhibition hall layout
With an SL2 development within the Inner Zone, HSE’s PADHI decision matrix will
indicate “Advise Against”. The decision matrix within PADHI does not exhibit the
shading shown in the Atkins report, however this shading is shown in the HSE document
SPC/Tech/Gen/22, which was the document detailing HSE's call-in policy and procedure at
the time of the Atkins assessment. This document has since been updated, and the
update omits this matrix. The revised HSE policy is outlined in Section 4.3, below.
The Atkins report is a balanced qualitative / semi-quantitative risk assessment. It argues
that the zones are subject to a large uncertainty. The HSE zones are set on the basis of
(as HSE classify it) “Cautious Best Estimate” (CBE). Others, including Atkins, might
classify the HSE approach as “excessively cautious”.
The Atkins report argues that, based on the Inspector's report from the RAM Brewery
Inquiry, the frequency of 10cpm is “excessively cautious”, particularly when used
together with consequence modelling which is also considered as “perhaps too
cautious”.
Our own understanding largely supports the Atkins approach. We believe that the basic
physics of Gasholder failure is such that events of the type selected by HSE as the
representative case for setting Consultation Zones cannot occur in normal operation.
There is no doubt that major failures of Gasholders have occurred, and can occur again,
but neither the frequency nor the consequences of the controlling event chosen by HSE -
a grounded Fireball with a likelihood of 10 cpm per year - is credible in our opinion.
We should caution, however, that HSE's CBE approach and modelling of the
representative event has been accepted by Planning Inspectors at two separate
Planning Inquiries, the latest being the RAM Brewery Inquiry, albeit on both occasions it
6PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
was recognised that significant levels of caution had been applied in HSE's selection of
both frequency and consequence.
There is little doubt that if this planning application were to go to an Inquiry, the
Planning Inspector and Secretary of State (SoS) would again be likely to agree with
HSE's interpretation and application of PADHI.
4.2. What is the risk?
There is no argument that additional people working in and visiting the proposed
development will increase the residual risk from the gasholder facility. The issue to be
determined are whether that level outweighs the benefits of the development.
It is therefore appropriate for the Planning Authority to ask how strong this “Advise
Against” is in order to balance an understanding of the strength of the AA against any
known societal and economic benefits of the planning application.
Atkins opinion, stated in their Risk Assessment, and which we agree with, is that even
with the HSE set zones this is not a strong “Advise Against”. It is in the first block of
“Advise Against” in the PADHI matrix but, given the binary nature of PADHI, this does
not tell the full story.
The inherent cautious best estimate nature of setting the HSE zones, and the existing
land use around the gasholder lead to a reasonable conclusion that individual risks would
remain largely unchanged and societal risks would be marginally increased by the
presence of the superstore.
Atkins support the latter conclusion with the calculation of Scaled Risk Integral for the
site, which is one of the tests used by HSE to determine call-in for PADHI AA cases, and
which Atkins show to be above HSE's “substantial risk” criterion, but well below HSE's
call-in criteria.
We agree with Atkins that there appear to be no issues arising from the major hazards
present at this planning application which would be expected to automatically trigger a
call-in decision by HSE. The HSE guidance which was in force at the time of the Atkins
risk assessment (SPC/TECH/GEN/22) states:
If the AA decision was based on a combination of SL and Zone that just gives an AA decision
i.e. SL2 and IZ, SL3 and MZ or SL4 and OZ . . . a standard reply should be sent to the LPA . . .
indicating that HSE will not ask for the case to be called in. No further action is required.
This development is an SL2 and IZ, and thus, on the basis of the above, should not
normally be considered for a call-in request.
Since that date however, in August 2011, HSE published a new set of guidelines
(SPC/TECH/GEN/45). This update (which was undertaken without any consultation)
toughens up the guidance: removing the no call in if only one cell away advice and
stiffening the test for applications in the SRI 500,000 to 750,000 range.
7PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
Despite this change, and because we generally support the SRI calculations shown in the
Atkins report which are far below the 500,000 trigger (see below) where HSE would
“consider recommending call-in”:
HSE has developed a method of assessing the degree of societal risk associated with a
proposed development known as the Scaled Risk Integral (SRI). In appropriate cases HSE
will apply SRI.
Where the level of societal risk is substantial HSE will initiate its internal call-in procedure in
order to give further consideration to the application.
HSE will give the most serious consideration to the application where the level of societal
risk is approaching intolerable such that development in the location would create serious
public safety concerns. This would be cases where the SRI is between 500,000 and 750,000
which means that HSE will consider recommending call-in for cases of exceptional concern.
Where the level of societal risk is so high that it is intolerable HSE will request call-in, this
would be cases where the SRI exceeds 750,000.
The SRI in this case is expected to be between 100,000 and 200,000 (depending on
assumptions used), however the following comments2 regarding SRI have been made by
Martin Goose, who recently retired as the head of HSE's Major Hazards Assessment Unit:
It must be borne in mind that SRI can only be used in cases where HSE has carried an
assessment of individual risk for the site in question. This is usually referred to as quantified
risk assessment (QRA). Assessments using QRA are generally used for all toxic substances
and some flammable substances where the hazardous effects, should there be loss of
containment, are substantially directional. For most situations involving flammable
substances, individual risk is not calculated and a system called the protection concept is
used instead. SRI cannot be used as an aid to judgement in such cases.
Based on the above SRI quantum and commentary on the validity of SRI for judgement
in cases such as this, we believe that it is again highly unlikely that HSE would request
call-in for this development proposal.
4.3. HSE call-in policy (in further detail)
The following is taken from HSE's website (hse.gov.uk/landuseplanning/advice.htm):
“In the last 30 years, HSE has only requested that five planning applications in England and
Wales be called-in. In deciding whether or not to do this, HSE will consider a number of
factors, including the type and size of the proposed development, and the numbers and
type of people who will be exposed to the risk (is it a vulnerable population such as
children, old people, etc?). HSE’s policy on deciding on potential call-in cases is contained in
SPC/Tech/Gen/49.”
2
A Note on HSE's Use of Risk Integrals, Martin Goose, 2011
8PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
The following has been extracted from SPC/Tech/Gen/49 (Version 1, 15 August 2011) to
provide London Borough of Lambeth with further insight into HSE's policy and
procedure when considering a call-in:
Background
...
6. It is an exceptional course of action for HSE to request that an application be called-in
and it will only consider doing so in cases of exceptional concern or where important safety
or policy issues are at stake. HSE will normally consider its role to be discharged when it is
satisfied that the HSA/PA has given HSE’s advice the most careful consideration and it is
acting in full understanding of that advice and the consequences that could follow.
...
Call-in criteria
8. When a HSA/PA has informed HSE that it is minded to go against its advice, HSE will
consider whether to request that the application be called in by the SoS or, as the case may
be, the Welsh Ministers or Scottish Ministers. HSE will consider all relevant factors, but will
treat the presence of any of the following criteria as a significant factor in favour of
requesting call-in.
Any significant residential development or development for vulnerable populations in the
inner zone:
v Close to the major accident hazard such that the consequences to people from a
major accident are very severe;
v ‘Significant residential development’ means three or more residential units,
thereby placing 8-10 people at high risk;
v A vulnerable population would include the young (e.g. schoolchildren), the elderly
(e.g. residents of a nursing home), or the infirm (e.g. hospital patients). These
population groups would be more susceptible to harm from the hazardous
substance and more at risk as they would be difficult to evacuate in an emergency.
The risk of death from a major hazard exceeds the Tolerability of Risk (TOR) tolerability
limit for a member of the public.
v If this limit is ever reached or given the uncertainty in calculating risk values the
risks are so high that the actual risk from the site could have crossed the TOR limit.
There are substantial numbers of people in the proposed development exposed to a
significant level of risk
v HSE has developed a method of assessing the degree of societal risk associated with
a proposed development known as the Scaled Risk Integral (SRI). In appropriate
cases HSE will apply SRI.
v Where the level of societal risk is substantial HSE will initiate its internal call-in
procedure in order to give further consideration to the application;
v HSE will give the most serious consideration to the application where the level of
societal risk is approaching intolerable such that development in the location would
create serious public safety concerns. This would be cases where the SRI is between
500,000 and 750,000 which means that HSE will consider recommending call-in for
cases of exceptional concern;
9PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
v Where the level of societal risk is so high that it is intolerable HSE will request call-
in, this would be cases where the SRI exceeds 750,000.
The endangered population is particularly sensitive.
v For example, the young, the elderly or those under residential medical care.
It is a challenge to HSE’s risk criteria for land use planning.
For example, where a HSA/PA repeatedly sets aside HSE’s advice, which would result in a
cumulative increase in the population around a major hazard installation/pipeline.
4.4. Implications
If a development only just fails to meet the LUP criteria, the HSE would not normally call
it in, provided that the LPA understands the reasons for the HSE's advice and has made
an informed decision, balancing the risks against socio-economic benefits.
Our research into gasholder events, including those cited by the HSE, leads us to the
considered opinion that whilst it is self-evident that major events can occur at Gasholder
sites, no events in the UK in the last one hundred years have caused fatalities, nor could
any be realistically described or modelled as a fireball, much less a grounded fireball of
the type used by the HSE for setting the latest LUP zones around gasholders.
Below, we have expanded on some of the issues which we believe are pertinent to the
understanding of the risks, or should be given particular consideration by London
Borough of Lambeth in the decision making process:
1. It is highly unlikely that a gasholder will fail catastrophically and instantaneously
release 50% of the contents.
2. We also believe that any “sudden” loss of gas from a gasholder should not be
represented as a concentrated mass of natural gas at ground level that can then be
modelled as a fireball event, which is the HSE approach to determine the revised
consultation distances.
3. A grounded fireball event would be expected to have severe consequences as a
result of the size of the fireball and also the high levels of thermal radiation
associated with the fireball, yet it appears that none of the events found in literature
exhibit such characteristic damage. It is therefore possible that events which might
be described as a “rising fireball” in reporting the event have occurred, but the
consequences of such events are far less than those modelled by the HSE.
4. Historical information on minor incidents and accidents of gasholders is probably
vastly underreported. At face value, HSE data from the 1970’s through the 1990’s
indicates that the likelihood of a release in the latter years is some ten-times that in
the 1970’s, yet one might expect the Gasholders that have been retained to be those
which tend to be in better condition. An implication of this is that reporting of
incidents in the 1970’s (and, we assume, prior to this) was imperfect, presumably
because these incidents did not lead to any harm or damage to people or property
outside the Gasholder area.
10PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
5. With a working assumption that ignited releases would probably be recorded,
particularly for significant events, two conclusions can be inferred from this. The
first is that any frequency of a small release which is based solely on historical data
going back to the 1950’s, or before, may be optimistic. A second conclusion is that
the likelihood of any release of gas leading to a flammable event (which are much
more likely to have been reported than minor events) is exceptionally low, which
implies that the probability of ignition given a release is also low. This is particularly
so since the mid-1980’s, since when - to our understanding - there have been few
records of seal fires from gasholders.
6. Qualitative improvements appear to have resulted in quantitative reductions in
major events: inspection and maintenance have been improved; the change from
town gas to natural gas will have had some effect, though this is perhaps balanced
by an increase in the number of ignition sources close to gasholders.
7. Many mechanical systems exhibit variable failure rates over time approximating to
what is termed a ‘bathtub curve’; the rate of failure just after commissioning and at
the end of useful life will be significantly higher than the average. An argument
could be put forward to show that significant failures which are recorded in the early
1900’s are as a result of ‘infant mortality’. Any installation (such as this gasholder
site) which has successfully passed this infant mortality stage and is being well-
maintained should exhibit a low failure rate.
8. A number of flammable events associated with gasholders in the early 20th Century
were caused by poor practices which would not be allowed today.
9. As an example, the mechanism of ignition for the most of the ignited events
recorded by the HSE Brit Oval partial disclosure and found during the course of our
own research would, in our opinion, and with the exception of high-energy knock-on
events and terrorism events, all be prevented under the current regulations (e.g.
DSEAR) intended to provide additional measures of safety in hazardous zones.
10. The frequency of gasholder failure and flammable gasholder events is therefore far
lower than in the early years of the 20th Century.
11. As the proposed development should not affect the frequency or outcome of any
event which might occur at the Gasholder site, the individual and societal risk levels
to the existing, unchanged population groups will not be in any way affected by the
development.
12. One way to look at risks is to divide them into two distinct types: voluntary and
involuntary. Voluntary risks are undertaken with knowledge of the possible
consequences. Before participating in such activities (flying across the country or
scuba diving), people are aware of the chance of injury or death and accept the risk.
In contrast, involuntary risks are those that are unwittingly taken or are outside the
public's control. Examples of involuntary risk are exposure to air pollution or
lightning strikes.
13. The HSE would generally advise against individual risk levels which would be
significant compared to other risks to which they are exposed in everyday life.
11PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
14. Table 4.1, below, is a comparison of the risk per annum of a “dangerous dose or
worse” from the consultation zone controlling event at Kennington against the
annual risk of death averaged over the entire population for more familiar risks, the
latter being taken from the HSE website (HSE) with the exception of England and
Wales homicide risk which was extracted from The Scottish Government website
(The Scottish Government, 2000).
Table 4.1: Risk comparison
(UK wide unless otherwise stated, italicised categories refer to the Chivas Brothers
Beefeater Distillery development)
Cause Annual risk
Cancer (Fatality) 1 in 387
Injury & poisoning (Fatality) 1 in 3137
Road accidents (Fatality) 1 in 16800
Homicide (Fatality, England & Wales) 1 in 74627
Gas incident (Fatality) 1 in 1510000
Most Exposed Worker3 (Dangerous Dose) 1 in 1000000
Lightning (Fatality) 1 in 18700000
Typical Customer (Dangerous Dose) 1 in 20000000
Most Exposed Worker4 (Fatality) 1 in 100000000
Typical Customer (Fatality) 1 in 2000000000
15. We note from the HSE documents that LUP policy is to permit development where
this might only cause a minimal increase in fatalities. This development would
appear to fall within that criterion.
16. This development will increase the residual risk at Kennington, but the likely
individual risk is low and the associated increases in societal risk are likely to be
marginal, and should be considered by the LPA against the social and other benefits
of this development.
17. A summary of desirable design features includes:
v Restrict usage of open spaces / roof terraces;
v Minimise window openings facing gasholders;
v Specify shatterproof and thermal glass for windows facing gasholders;
v Ensure adequate provision is made for evacuation away from the gasholders in
the event of minor events and fires.
4.5. Conclusions
Although there is no evidence that the Kennington gasholder is unsafe, it is incumbent
on the developer to demonstrate, first, that the proposed development does not
substantially increase the residual risk and, secondly, provide the LPA with sufficient
3
Dangerous dose or worse; assumes an occupancy of 1.
4
Based on the HSE model that a dangerous dose equates to 1% fatality probability.
12PEER REVIEW OF RISK ASSESSMENTS IN RESPECT OF GASHOLDER LUP January 16, 2012
information to allow the safety issues to be balanced against the socio-economic
benefits.
Having reviewed the document, discussed it briefly with Atkins, and tested it against our
own knowledge of gasholder Land Use Planning, we have confidence in stating that the
Risk Assessment by Atkins is adequate to fulfil this purpose.
We agree with Atkins that there is should be no more than a very low likelihood - based
on the known criteria that HSE states it uses - that this proposed development will result
in a call-in request by HSE on safety grounds.
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