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ENVIRONMENTAL RISK ASSESSMENT OF
BULK LIQUID STORAGE FACILITIES
A SCREENING TOOL
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ENVIRONMENTAL RISK ASSESSMENT OF
BULK LIQUID STORAGE FACILITIES
A SCREENING TOOL
September 2006
Published by
ENERGY INSTITUTE, LONDON
The Energy Institute is a professional membership body incorporated by Royal Charter 2003
Registered charity number 1097899
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The EI gratefully acknowledges the financial contributions towards the scientific and technical programme from the following
companies:
BG Group
BHP Billiton Limited
BP Exploration Operating Co Ltd
BP Oil UK Ltd
Chevron
ConocoPhillips Ltd
ENI
ExxonMobil International Ltd
Kuwait Petroleum International Ltd
Maersk Oil North Sea UK Limited
Murco Petroleum Ltd
Nexen
Shell UK Oil Products Limited
Shell U.K. Exploration and Production Ltd
Statoil (U.K.) Limited
Talisman Energy (UK) Ltd
Total E&P UK plc
Total UK Limited
Copyright 2006 by the Energy Institute, London:
The Energy Institute is a professional membership body incorporated by Royal Charter 2003.
Registered charity number 1097899, England
All rights reserved
No part of this book may be reproduced by any means, or transmitted or translated into a machine language without the written
permission of the publisher.
The information contained in this publication is provided as guidance only and while every reasonable care has been taken to
ensure the accuracy of its contents, the Energy Institute cannot accept any responsibility for any action taken, or not taken, on
the basis of this information. The Energy Institute shall not be liable to any person for any loss or damage which may arise from
the use of any of the information contained in any of its publications.
The above disclaimer is not intended to restrict or exclude liability for death or personal injury caused by own negligence.
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CONTENTS
Acknowledgements
Abbreviations
1. SCOPE AND OBJECTIVES
Introduction
BackgroundObjectives
1
1
12
2. SCREENING ASSESSMENT METHODOLOGY
Steps 1 3 Initial Assessment
Step 4 Aquifer (Groundwater) Vulnerability
Assessment
Step 5 Tank Assessment
Step 6 Bund Assessment
Step 7 Risk Assessment
4
4
8
13
18
20
3. INFORMATION RESOURCES 22
4. REFERENCES 23
APPENDIX A EXCEL SPREADSHEET 24
APPENDIX B RISK PHRASES 25
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ACKNOWLEDGEMENTS
This document was produced by:
Atkins Limited,
Woodcote Grove
Ashley Road
Epsom
Surrey
KT18 5BW
Tel: 01372 726140
Fax: 01372 740055
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ABBREVIATIONS
API American Petroleum Institute
BAT Best Available Techniques
BRef BAT Reference Note
EEMUA Engineering Equipment Materials and Users Association
HDPE High Density Polyethylene
IPPC Integrated Pollution Prevention and Control
SEPA The Scottish Environment Protection Agency
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1. SCOPE AND OBJECTIVES
INTRODUCTION
1.1 This document describes a screening tool for assessing the risk to the environment of above-
ground bulk liquid storage tanks, in terms of the potential for an uncontained release of a
hazardous material to impact upon a nearby sensitive receptor, and in particular groundwater
resources.
1.2 The screening methodology is based upon a standard source-pathway-receptor model, and
takes into account factors such as the hazardous properties of the stored material, the
proximity and sensitivity of nearby surface and sub-surface receptors, the geological setting of
the storage tank site, the physical condition of the tank and its surrounding bund,
maintenance and monitoring regimes, and the availability of containment and spillage control
measures.
1.3 The screening tool is contained in Appendix A. It is still under development and is being
released for field-trial by storage tank operators. It is currently structured in the form of a
Microsoft Excel spreadsheet, with the input parameters being selected by the user from
picklists. Future releases of the tool are likely to be in the form of a run-time programme in
Microsoft Access with improved data management and integral help menus. The ultimate
layout and functionality of the tool may vary depending upon the feed-back received from
operators.
1.4 The final document, when published, will be applicable to sites across Europe, and will
support requirements in the IPPC Reference Document on Best Available Techniques on
Emissions from Storage, published in January 2005 by the European Commission.
BACKGROUND
1.5 The European Directive 96/61/EC on integrated pollution prevention and control (IPPC) as
enacted in the UK under the Pollution Prevention and Control Act, 1999 requires operators
of bulk hazardous materials storage facilities (an Installation) to use Best Available
Techniques (BAT) to prevent or minimise pollution from the operation of the installation, such
that significant pollution will not be caused1
. Guidance on what represents BAT is provided in
1Bulk storage is covered under: A) The loading, unloading or other handling of, the storage of, or the physical, chemical or
thermal treatment of: (i) crude oil, (ii) stabilised crude petroleum, (iii) crude shale oil, (iv) any associated gas or condensate, and
(v) emulsified hydrocarbons intended for use as a fuel, and B) The storage of chemicals in bulk: acrylates, acrylonitrile,
anhydrous ammonia, anhydrous hydrogen fluoride, toluene di-isocyanate, vinyl chloride monomer, and ethylene.
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the Reference Document on Best Available Techniques on Emissions from Storage [Ref 1.1],
referred to as the Storage BRef note.
1.6 In the UK, an installation (new or existing) covered by the Directive must obtain a permit, from
the Environment Agency or the Scottish Environment Protection Agency (SEPA), to continue
to operate. A permit must be applied for, and an evaluation of BAT for the installation a
BAT Assessment must be included within the application.
1.7 Above-ground storage tanks have the potential to cause pollution to the surface and sub-
surface environments via the release of hazardous liquid, where a release can arise through
leakage and corrosion-induced failure of the tank and its associated pipework, tank over-filling
or, in the extreme, tank rupture. The likelihood of the occurrence of a release will be
dependent upon a range of factors such as the tanks design, operational procedure, the
extent of gauging and alarms, the degree of corrosion protection, and the extent of inspection
and monitoring regimes, etc.
1.8 Tanks are also equipped with bunds which provide a measure of security against the spread
of pollution should a release occur. However, the effectiveness of this secondary
containment measure including its effectiveness at preventing a spillage from penetrating
the underlying ground and any groundwaters is dependent upon the bunds size, materials
of construction and physical condition. The ultimate impact on the environment of a release,
should it not be contained within a bund, will depend upon the presence of nearby sensitive
receptors such as potable groundwaters.
1.9 The overall environmental risk posed by a storage facility will therefore be dependent upon
the condition of the Source (ie., the storage tank and its hazardous liquid contents), the
presence of a Pathway (ie., made possible by a pervious bund and pervious subsurface
geologic formations), and the presence of a Receptor, such as an aquifer.
1.10 A detailed risk assessment of a storage tank facility can be a time-consuming and costly
undertaking. For this reason the Energy Institute commissioned the screening methodology
described below to enable storage tank operators to carry out a rapid assessment of their
facilities based upon readily available, or easily obtainable information on the receiving
environment, and the design and operation of the tank and bund arrangement. The purpose
of the assessment was to enable the environmental risk to be determined in qualitative terms
(High, Medium or Low), and options for the reduction of this risk to be explored. A secondary
intended purpose was to support Applications and BAT Assessments required under IPPC,
and general interactions with the Environment Agency on the subject of bulk hazardous
materials storage risk.
OBJECTIVES
1.11 The objectives of the screening tool are as follows:
To provide a qualitative assessment of the risk to the environment of above-ground
bulk liquid storage tanks, in terms of the potential for an uncontained release of a
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hazardous material to impact upon a nearby sensitive receptor, and in particular
groundwater resources;
To identify additional measures which could be implemented to reduce the
environmental risk of a storage arrangement, and assess their relative significance;
and,
To support an Application and BAT Assessment required under IPPC.
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2. SCREENING ASSESSMENT METHODOLOGY
2.1 The screening assessment methodology is based on a seven step process:
Steps 1 to 3 Initial Assessment;
Step 4 Aquifer (Groundwater) Vulnerability Assessment;
Step 5 Tank Assessment;
Step 6 Bund Assessment; and,
Step 7 Risk Assessment.
2.2 Steps 5 and 6 also enable a user to enter cost data on specific tank and bund mitigation
options and thereby carry out an initial evaluation of the likely costs of risk reduction
measures. The assessment stages are described below and are illustrated overleaf in the
form of a flow diagram.
STEPS 1 - 3 INITIAL ASESSMENT
2.3 The purpose of the Initial Assessment is to determine whether, for the storage arrangement,
there is a source-pathway-receptor linkage. If such a linkage does exist then a full screening
assessment is required, and Steps 4 through 7 must be completed. If the linkage is broken,
for example due to the absence of receptors, then no further assessment is necessary.
2.4 Steps 1 to 3 should be completed as follows:
Step 1
2.5 A description of the stored material should be written in the response box, for example Fuel
Oil, Diesel, etc. The description is for record purposes only and does not affect the
outcome of the assessment.
Figure 1 Step 1 Data Input
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Figure 2 Screening Assessment Flowchart
What is the
stored material?
Is the material
hazardous?
Are there any
nearby sensitivereceptors?
STOP
No furtherassessment
necessary
Yes
No
No
Complete Aquifer
(Groundwater)
Vulnerability
Assessment
Yes
Complete Tank
Assessment
Complete Bund
Assessment
Risk Assessment
Medium
Risk
High
Risk
Low
Risk
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Step 7
Is Risk
ALARP
STOP
No further
assessment
necessary
Yes
No
STOP
No further
assessment
necessary
Identify risk
mitigation options
and ascribe costs
What is the
stored material?
Is the material
hazardous?
Are there any
nearby sensitivereceptors?
STOP
No furtherassessment
necessary
Yes
No
No
Complete Aquifer
(Groundwater)
Vulnerability
Assessment
Yes
Complete Tank
Assessment
Complete Bund
Assessment
Risk Assessment
Medium
Risk
High
Risk
Low
Risk
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Step 7
Is Risk
ALARP
STOP
No further
assessment
necessary
Yes
No
STOP
No further
assessment
necessary
Identify risk
mitigation options
and ascribe costs
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Step 2
2.6 The hazardous nature of the stored material has been defined in the screening tool by means
of standard risk phrases, a complete listing of which is given in Appendix B. Those applicable
to the stored material which if not known can be obtained from Materials Safety Data
Sheets should be selected from the pick list as illustrated in Figure 3. It is not intended that
all appropriate risk phrases be recorded and space has therefore only been left for the entry
of five.
2.7 If a single risk phrase is selected for the stored material, it is defined as hazardous and the
assessment box will turn red, as illustrated in Figure 3. If none of the risk phrases apply then
the response cells under item 2.0 should be left blank. If a description is entered in error it
can be removed using the Delete key on the keyboard.
Figure 3 Step 2 Data Input
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Step 3
2.8 As a final step in the initial assessment it is necessary to identify the presence of nearby
sensitive receptors. The options are available for selection from the response box pick lists
are listed below. If a single sensitive receptor is selected from the pick list the assessment
box will turn red, as illustrated in Figure 4.
The site is situated above an aquifer.
The site is situated in a Groundwater Source Protection Zone.
There is a public water abstraction point within a 5 km radius of the site.
There is a private potable water abstraction point within a 5 km radius of the site.
There is a non-tidal surface water course within a 5 km radius of the site.
There is a public water abstraction point from the non-tidal surface water course within a distance of 5 km
downstream.
There is a private potable water abstraction point from the non-tidal surface water course within a distance of 5 kmdownstream.
There is a tidal surface water course within a 5 km radius of the site.
There is a public water abstraction point from the tidal surface water course within a distance of 5 km.
There is a private potable water abstraction point from the tidal surface water course within a distance of 5 km.
Note: If the above information is not known, details can be obtained from the Information Resources listed in
Chapter 3 of this report.
2.9 The outcome of the Initial Assessment is listed in the OUTCOME box at the bottom of the
spreadsheet (reproduced here in Figure 4). The outcome options are summarised in Table 1
below.
Table 1 Outcome of Initial Assessment
Is the material stored hazardous?
Are there any
nearby receptors?Not Hazardous Hazardous
No nearby
sensitive
receptors
STOP - No further
assessment
necessary
STOP - No further
assessment
necessary
Nearby sensitive
receptors
STOP - No further
assessment
necessary
CARRY OUT RISK
ASSESSMENT - GO
TO STEP 4
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Figure 4 Step 3 Data Input
STEP 4 AQUIFER (GROUNDWATER) VULNERABILITY ASSESSMENT
2.10 The purpose of Step 4 is to provide the information upon which an assessment of, primarily,
groundwater vulnerability can be made. A response to Items 4.2 to 4.11 should be entered by
selecting the most appropriate option from the pick list within each response box (see
Figure 5). A list of the available options is provided in Table 2.
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Figure 5 Step 4 Data Input
2.11 For Step 4, a response must be returned; all response boxes (with the exception of Item 4.1
see below) must be completed. A predetermined score will then be allocated by the
screening tool to each response in order to calculate a measure of vulnerability. Where
information is not known, details should be available (for a small cost) from the Information
Resources listed in Chapter 3. Where this is not the case the option Dont know can beselected, although it should be noted that where this option is entered the highest level of
vulnerability will be assumed.
2.12 An evaluation of the environmental vulnerability is given at the foot of the data input sheet for
Step 4 in the form of a traffic light: green for Low vulnerability, orange for Medium and red
for High. The traffic light is reproduced as a band on the right hand side of the data entry
fields. Note that the evaluation changes dynamically as the responses are selected. On a
blank sheet, with no completed responses, it will default to red/High.
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Table 2 Step 4 Data Input
Item
NoAssessment Item Option
4.1 Geological Sequence beneath the Site -0 m to 1 m below ground level.
1m to 3m below ground level.
3m to 5m below ground level.
5m to 10m below ground level.
10m+ below ground level.
4.2 Depth to Groundwater
Don't Know.
Less than 5m of continuous clay in the unsaturated superficial deposits.
More than 5m of continuous clay in the superficial deposits.4.3Nature of the Deposits above the
Groundwater TableDon't Know.
Fractured.
Intergranular/fractured.
Intergranular.4.4 Nature of the Strata forming the Aquifer
Don't Know.Major Aquifer.
Minor Aquifer.
Non-aquifer.4.5
Type of Aquifer Beneath the Site/Tank
Farm
Don't Know.
0 m to 500 m radius.
500 m to 1 km radius.
1 km to 5 km radius.4.6
Closest Public Water Supplies
Abstracting from the Aquifer
Don't Know.
Inner (Zone I).
Outer (Zone II).
Total Catchment (Zone III).
None.
4.7 Groundwater Source Protection Zones
Don't Know.
0 m to 500 m radius.
500 m to 1 km radius.
1 km to 5 km radius.4.8
Closest Private Potable Water Supplies
Abstracting from the Aquifer
Don't Know.
0 m to 500 m radius.
500 m to 1 km radius.
1 km to 5 km radius.4.9
Closest Other Abstractions from the
Aquifer
Don't Know.
0 m to 500 m radius.
500 m to 1 km radius.
1 km to 5 km radius.4.10
Closest Surface Water
Course/Springs/Wetlands
Don't Know.
0 m to 500 m radius.
500 m to 1 km radius.
1 km to 5 km radius.4.11 Closest Ecological Systems
Don't Know.
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2.13 The response box in Item 4.1 should be used to enter a free form description of the geological
sequence beneath the storage tank site, based on existing site records or geological maps.
Examples of the information which could be recorded here, in illustration of the groundwater
vulnerability, are presented in Figure 6. However, it should be noted that no scoring is
allocated to the response, and the absence of information will not affect the ultimate outcome
of the screening assessment.
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Figure 6 Groundwater Vulnerability
No drift.
Thin unsaturated
zone ie high water
table
Major aquifer and
upgradient of nearby
potable water supply
borehole.
Thic
Larg
zon
tabl
Non
Dist
sour
Thick clay soil and
drift with deep water
table but potentially
rapid lateral
movement to river
possibly aided by
drainage systems.
Sandy drift
Moderate unsaturated
zone
Major\minor aquifer
and nearby potable
water supply borehole.
Complex drift
Moderate unsaturated
zone
Minor aquifer and
distant from any potable
water supply borehole.
Soil
Drift
Major aquifer
Minor aquifer
Non aquifer
Rest groundwater
level
Pumping
groundwater level
No drift.
Thin unsaturated
zone ie high water
table
Major aquifer and
upgradient of nearby
potable water supply
borehole.
Thic
Larg
zon
tabl
Non
Dist
sour
Thick clay soil and
drift with deep water
table but potentially
rapid lateral
movement to river
possibly aided by
drainage systems.
Sandy drift
Moderate unsaturated
zone
Major\minor aquifer
and nearby potable
water supply borehole.
Complex drift
Moderate unsaturated
zone
Minor aquifer and
distant from any potable
water supply borehole.
Soil
Drift
Major aquifer
Minor aquifer
Non aquifer
Rest groundwater
level
Pumping
groundwater level
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STEP 5 TANK ASSESSMENT
2.14 The purpose of Step 5 is to provide the information upon which an assessment can be made
of the likelihood of a release occurring from an above ground storage tank based upon factors
such as its design, extent of gauging, etc. Once again a response to Items 5.3 to 5.21 should
be entered by selecting the most appropriate option from the pick list within each response
box; a response must be returned. A list of the available options is provided in Table 3.
2.15 Item 5.1 enables the recording of a tanks unique identification number. However, a response
to this item is not essential. The response to Item 5.2 is read from Step 1 of the Initial
Assessment.
Table 3 Step 5 Data Input
Item
No Assesment Item Option
5.1 Tank reference number -
5.2 Tank material contents -
0 - 5,000 m3
5,000 - 20,000 m3
20,000 - 100,000 m3
5.3 Tank maximum working capacity
100,000 m3 +
British Standard, or equivalent.
API, or equivalent.
Other design code, not equivalent to recognised industry standard.5.4 Tank Design Code
Don't know.
0 - 5 m
5 - 10 m
10 - 15 m5.5 Average product working height
15 m +
Yes5.6 Is the tank heated?
No
Emergency repsonse plans in place.
No emergency response plans.5.7 Emergency Response Plans
Don't know.
Emergency response equipment available for rapid mobilisation.
Emergency response equipment available but not for rapid mobilisation.
No emergency response equipment available.5.8 Emergency Response Equipment
Don't know.
Inspection based on risk-based variable time methodology as per
EEMUA 159 or equivalent.
Internal tank inspection frequency for the product stored is equal to or
better than those provided in EEMUA 159 or equivalent.
5.9 Out-of-service Internal tankInspections
Don't know
Tank level measurement. Manual. No alarms.
Tank level measurement. Instrumentational. No alarms.
High level alarm. Annunciation only.
High level alarm. Annunciation & automatic shut-down.
5.10 Tank gauging & alarms
High level & High High level alarms. Annunciation only.
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Item
NoAssesment Item Option
High level and High High level alarms. Annunciation & automatic shut-
down.
None.
Don't know.
Written operator instructions identifying action in the event of a leak or
spill, plus training and drills.
Written operator instructions which identify action in the event of a leak
or spill. No training and drills.
Training and drills only. No written instructions.
None.
5.11 Spillage Response
Don't know.
Observations made for leaks, etc on a daily basis.
Observations made for leaks, etc on a weekly basis.
Observations made for leaks, etc on a monthly basis.
Tank and pipework not subject to regular observation.
5.12 Maintenance and inspection
Don't know.
Visual and detailed external tank inspection frequencies for the product
stored are equal to or better than those provided in EEMUA 159 orequivalent.
Visual and detailed external tank inspections undertaken but less
frequent than recommended in EEMUA 159 or equivalent.
5.13In-service detailed external tank
inspection
Don't know.
Single skin bottom.
Double skin bottom.5.14 Tank bottom design
Don't know.
Steel.
Concrete.
High-density polyethylene.
Clay.
Sand or soil.
Bit-sand.
5.15 Tank under-bottom materials
Don't know.
Cathodic protection.
No cathodic protection.5.16 Tank cathodic protection
Don't know.
Internal bottom protective coating - Thin Film.
Internal bottom protective coating - Thick Film (Glass Flake).
Internal bottom protective coating - Thick Film (Laminate).
Additional corrosion allowance on bottom plates.
Product(s) stored contains adequate corrosion inhibiter.
None.
5.17 Tank corrosion protection
Don't know.
Visual perimeter leak detection systems only.
Visual perimeter leak detection systems plus electronic sensors.None.
5.18 Under-tank leakdetection/monitoring
Don't know.
Monitoring wells near to tank site only.
Inventory reconciliation only.
Monitoring wells and inventory reconcilliation.
None.
5.19 Off-tank leak detection systems
Don't know.
5.20 Floor inspection techniques Full floor coverage using test equipment (eg magnetic flux).
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Item
NoAssesment Item Option
Partial coverage using test equipment (eg spot measurements with
ultrasonics).
Visual inspection only.
Don't know.
2.16 The worksheet for Step 5 is set out in two parts as illustrated in Figure 7. The left hand side
of the sheet is designed for entry of the storage tank details. A traffic light evaluation is given
of the risk posed by the tank and bund together. The evaluation is given at the foot of the
input table (labelled as Tank & Bund Risk Rating) and as a band on the right hand side of
the data entry fields. The format of the traffic light is the same as for Step 4, ie., green for
Low risk, orange for Medium and red for High. A second traffic light is given at the very
bottom of the table and labelled as Total Risk Rating. This is the outcome of the
assessment, as described later in Step 7.
2.17 The purpose of the table on the right hand side of the worksheet is to enable the selection
and costing of mitigation options to investigate whether the tank and bund risk can be
reduced and at what overall cost. Where relevant, mitigation options can be selected from
the pick lists provided (a list of available options is provided in Table 4 below). As an
example, if under Item 5.10 a response of Tank level measurement. Manual. No alarms. is
entered, then a mitigation option of, say, Install high level alarm. Annunciation & automatic
shut-down. could be selected. Costs are then ascribed to this option as described below.
A revised evaluation of tank and bund risk is then given at the foot of the right hand side input table
(labelled as Mitigated Tank & Bund Risk Rating) and as a band on the left hand side of the data
entry fields. The evaluation uses the same format as above. The outcome of the revised assessment
(once again, as described in Step 7) is given as a second traffic light, at the bottom of the table and
labelled as Total Mitigated Risk Rating.
Table 4 Tank Mitigating Options
Item
NoAssessment Item Mitigating Options
5.7Emergency Response
Plans.Put emergency response plans in place.
5.8Emergency Response
Equipment.Install emergency response equipment.
Conduct internal tank inspection at a frequency, for the product stored, equal to or
better than those provided in EEMUA 159 or equivalent.5.9
Out-of-service Internal
tank Inspections Conduct inspection based on risk-based variable time methodology as per EEMUA
159 or equivalent.
Install tank level measurement. Instrumentational. No alarms.
Install high level alarm. Annunciation only.
5.10 Tank gauging & alarms.
Install high level & High High level alarms. Annunciation only.
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Item
NoAssessment Item Mitigating Options
Install high level alarm. Annunciation & automatic shut-down.
Install high level and High High level alarms. Annunciation & automatic shut-down.
Produce written operator instructions.
Implement training and drills programme to supplement existing operator instructions.5.11 Spillage Response.
Develop written operator instructions together with training and drills.
Initiate a monthly programme of observation.
Initiate a weekly programme of observation.5.12Maintenance and
inspection.
Initiate a daily programme of observation.
5.13In-service detailed
external tank inspection
Conduct visual and detailed external tank inspection at frequencies, for the product
stored, equal to or better than those provided in EEMUA 159 or equivalent.
5.14 Tank bottom design. Install double-skin bottom.
Investigate further.
Install steel under tank bottom.
Install bit-sand under tank bottom.
Install concrete under tank bottom.
Install high-density polyethylene under tank bottom.
5.15Tank under-bottom
materials.
Install clay under tank bottom.
5.16Tank cathodic
protection.Install cathodic protection.
Investigate further.
Install internal bottom protective coating - Thin Film.
Install internal bottom protective coating - Thick Film (Glass Flake).
5.17Tank corrosion
protection.
Install internal bottom protective coating - Thick Film (Laminate).
Install visual perimeter leak detection systems only.5.18 Under-tank leak
detection/monitoring. Install visual perimeter leak detection systems plus electronic sensors.
Investigate feasibility.
Install monitoring wells near to tank site only.
Conduct inventory reconciliation only.
5.19Off-tank leak detection
systems.
Install monitoring wells and conduct inventory reconciliation.
Conduct visual inspection only.
Inspect by partial coverage using test equipment (eg spot measurements with
ultrasonics).
5.20
Floor inspection
techniques.
Inspect by full floor coverage using test equipment (eg magnetic flux).
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Figure 7 Step 5 Data Entry Tables
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2.18 Where a mitigation option is selected the following cost data should be entered in the boxes
provided:
Remaining Tank Life (Years)
Design Cost ()
Installation Cost ()
Annual Operating Cost ()
Annual Maintenance and Repair Costs ()
Replacement Costs ()
Design Life of Mitigation Option (Years)
Residual Value (e.g. scrap) ()
The cost total will be calculated automatically.
2.19 It is recognised that the costs of mitigation options will vary between sites and even between
tanks. For this reason the above cost data must be directly entered into the spreadsheet by
the user. It is not generated automatically and can not be selected from pick lists.
2.20 It should be noted that the risk reported in Steps 5 and 6 is for the tank and bund together.
For this reason the Step 6 bund data entry table (see below) should be completed, to
determine unmitigated tank and bund risk, before investigation of the mitigation options.
STEP 6 BUND ASSESSMENT
2.21 Step 6 is similar to Step 5 but is concerned with the design and condition of the storage tank
bund rather than the tank itself. A response to Items 6.1 to 6.7 must be entered in the left
hand side table by selecting the most appropriate option from the pick list within each
response box. A list of the available options is provided in Table 5. The traffic light risk
evaluation given at the foot of the left hand side table and as a band along its right hand side
is a reproduction of the traffic light system in Step 5.
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Table 5 Step 6 Data Input
Item
NoAssesment Item Option
Equal to or greater than 110% of tank working volume.Equal to or greater than 100% of tank working volume but less than
110%.
Equal to or greater than 80% of tank working volume but less than
100%.
Less than 80% of tank working volume.
6.1 Bund net capacity
Don't know.
All pipework within bund runs above ground.
All pipework within bund runs below ground.
Pipework in bund runs both above and below ground.6.2 In-bund pipe-work
Don't know.
Soil/clay: compacted and degree of compaction known and maintained.
Soil/clay: compacted but not engineered.
Soil/clay: not compacted.
Clay/Bentonite liner throughout.
Asphalt liner throughout.
Concrete liner throughout.
HDPE liner throughout.
Perimeter liner.
6.3Bund floor materials of
construction
Don't know.
Soil/clay walls: designed, engineered and maintained.
Concrete walls: access points backfilled with soil/clay - designed,
engineered and maintained.
Concrete walls: access points backfilled with soil/clay - condition not
known.
Soil/clay walls: condition not known.
6.4 Bund wall materials of construction
Don't know.
Formal engineering inspections indicate good condition with no cracks or
other damage.
Visual inspections indicate good condition with no cracks or other
damage.
Cracks and damage to bund potentially prejudicial to spillage
containment.
6.5 Physical condition of bund floor
Don't know.
Formal engineering inspections indicate good condition with no cracks or
other damage.
Visual inspections indicate good condition with no cracks or other
damage.
Cracks and damage to bund wall potentially prejudicial to spillage
containment.
6.6 Physical condition of bund walls
Don't know.
Height and profile maintained to designed bund capacity.
Height and profile not maintained.6.7 Bund wall profile
Don't know.
2.22 As per Step 5, the table on the right hand side of the workbook enables the selection and
costing of mitigation options. A list of available options is provided in Table 6.
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Table 6 Bund Mitigating Options
Item
NoAssessment Item Mitigating Options
6.1 Bund net capacity Increase bund size 110% of tank working volume
Relocate some pipework above-ground.6.2 In-bund pipe-work
Relocate all pipework above-ground.
Cost to investigate.
Compact soil and clay bund.
Engineer previously compacted soil/clay bund or determine and maintain compaction.
Install clay/bentonite liner throughout.
Install asphalt liner throughout.
Install concrete liner throughout.
Install HDPE liner throughout.
6.3Bund floor materials of
construction
Install perimeter liner.
Cost to investigate type and condition of walls and access points.
Design, engineer and maintain soil/clay walls.6.4Bund wall materials of
construction
Design, engineer and maintain soil/clay access points in concrete walls.
Cost to investigate conditions of bund floor by visual inspections.
Cost to investigate conditions of bund floor by formal engineering inspections.6.5Physical condition of
bund floor
Repair/renew bund floor and validate by formal engineering inspections.
Cost to investigate conditions of bund floor by visual inspections.
Cost to investigate conditions of bund floor by formal engineering inspections.6.6Physical condition of
bund walls
Repair/renew bund wall and validate by formal engineering inspections.
6.7 Bund wall profile Engineer and maintain height and profile to designed bund capacity.
STEP 7 RISK ASSESSMENT
2.23 Based upon the information provided in Steps 4 through 6 the screening tool allocates a
qualitative ranking to the vulnerability of the environment and the storage tank and bund
arrangement. The overall level of risk is then determined by the tool according to the risk
matrix shown in Figure 7.
2.24 The screening tool determines the unmitigated risk posed by the existing storage tank
arrangement. This is given in the table headed Unmitigated Risk Rating. The risk may fall
within three categories:
Low, where the overall risk is considered to be acceptable, either because of low
environmental vulnerability or the low risk posed by the tank and bund design and
operation;
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Medium, where the scope for the implementation of risk mitigation measures and the
associated cost should be investigated further; and,
High, where the overall risk is considered to be unacceptable, and mitigation
measures must be implemented.
2.25 Where the screening tool determines that the overall level of risk is Low, the assessment is
concluded and no further work is necessary. Where a risk rating of either Medium of High is
returned it is necessary to evaluate the mitigation options in Steps 5 and 6.
Figure 7 Step 7 Output
2.26 The effect on risk levels resulting from the implementation of various risk mitigation options is
recorded in the table headed Mitigated Risk Rating. Three risk levels are reported, namely
Low, Medium and High (as explained earlier, before any data is entered into the tool in Excel
format, it will default to a High risk rating). However, High is not an acceptable mitigated
rating, and mitigation options must be selected until such time as the rating is Medium or,
ideally, Low. At this point the assessment is concluded.
2.27 The costs associated with the selected mitigation options are summarised in the table headed
Cost of Mitigation.
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3. INFORMATION RESOURCES
3.1 Environmental risk information for UK sites can be obtained, on commercial terms, from a
number of sources which include:
Environment Agency (http://www.environment-agency.gov.uk/ )
Scottish Environment Protection Agency (SEPA) (http://www.sepa.org.uk/ )
Landmark Information Group (http://www.landmarkinfo.co.uk/corp/index.jsp )
http://www.environment-agency.gov.uk/http://www.environment-agency.gov.uk/http://www.sepa.org.uk/http://www.sepa.org.uk/http://www.landmarkinfo.co.uk/corp/index.jsphttp://www.landmarkinfo.co.uk/corp/index.jsphttp://www.landmarkinfo.co.uk/corp/index.jsphttp://www.sepa.org.uk/http://www.environment-agency.gov.uk/ -
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4. REFERENCES
4.1 Integrated Pollution Prevention and Control. Reference Document on Best Available
Techniques on Emissions from Storage. January 2005. European Commission.
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APPENDIX A EXCEL SPREADSHEET
Microsoft Office
Excel Worksheet
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APPENDIX B RISK PHRASES
The table below presents a complete list of standard risk phrases. Those used to define the
hazardous properties of the stored material as part of the Initial Assessment (Step 2) are unshaded.
The shaded phrases (R1 to R20, etc) have not been employed in the assessment as they are notdirectly relevant.
R1 Explosive when dry.
R2 Risk of explosion by shock, friction, fire or other sources of ignition.
R3 Extreme risk of explosion by shock, friction, fire or other sources of ignition.
R4 Forms very sensitive explosive metallic compounds.
R5 Heating may cause an explosion.
R6 Explosive with or without contact with air.
R7 May cause fire.
R8 Contact with combustible material may cause fire.
R9 Explosive when mixed with combustible material.
R10 Flammable.
R11 Highly flammable.
R12 Extremely flammable.
R14 Reacts violently with water.
R14/15 Reacts violently with water, liberating extremely flammable gases.
R15 Contact with water liberates extremely flammable gases.
R15/29 Contact with water liberates toxic, extremely flammable gases.
R16 Explosive when mixed with oxidising substances.
R17 Spontaneously flammable in air.
R18 In use, may form flammable/explosive vapour-air mixture.
R19 May form explosive peroxides.
R20 Harmful by inhalation.
R20/21 Harmful by inhalation and in contact with skin.
R20/21/22 Harmful by inhalation, in contact with skin and if swallowed.
R20/22 Harmful by inhalation and if swallowed.
R21 Harmful in contact with skin.
R21/22 Harmful in contact with skin and if swallowed.
R22 Harmful if swallowed.
R23 Toxic by inhalation.
R23/24 Toxic by inhalation and in contact with skin.
R23/24/25 Toxic by inhalation, in contact with skin and if swallowed.
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R23/25 Toxic by inhalation and if swallowed.
R24 Toxic in contact with skin.
R24/25 Toxic in contact with skin and if swallowed.
R25 Toxic if swallowed.
R26 Very toxic by inhalation.
R26/27 Very toxic by inhalation and in contact with skin.
R26/27/28 Very toxic by inhalation, in contact with skin and if swallowed.
R26/28 Very toxic by inhalation and if swallowed.
R27 Very toxic in contact with skin.
R27/28 Very toxic in contact with skin and if swallowed.
R28 Very toxic if swallowed.
R30 Can become highly flammable in use.
R31 Contact with acids liberates toxic gas.
R32 Contact with acids liberates very toxic gas.
R33 Danger of cumulative effects.
R34 Causes burns.
R35 Causes severe burns.
R36 Irritating to eyes.
R36/37 Irritating to eyes and respiratory system.
R36/37/38 Irritating to eyes, respiratory system and skin.
R36/38 Irritating to eyes and skin.
R37 Irritating to respiratory system.
R37/38 Irritating to respiratory system and skin.
R38 Irritating to skin.
R39 Danger of very serious irreversible effects.
R39/23 Toxic: danger of very serious irreversible effects through inhalation.
R39/23/24 Toxic: danger of very serious irreversible effects through inhalation and in contact with skin.
R39/23/24/25 Toxic: danger of very serious irreversible effects through inhalation, in contact with skin and if swallowed.
R39/23/25 Toxic: danger of very serious irreversible effects through inhalation and if swallowed.
R39/24 Toxic: danger of very serious irreversible effects in contact with skin.
R39/24/25 Toxic: danger of very serious irreversible effects in contact with skin and if swallowed.
R39/25 Toxic: danger of very serious irreversible effects if swallowed.
R39/26 Very Toxic: danger of very serious irreversible effects through inhalation.
R39/26/27 Very Toxic: danger of very serious irreversible effects through inhalation and in contact with skin.
R39/26/27/28 Very Toxic: danger of very serious irreversible effects through inhalation, in contact with skin and if
swallowed.
R39/26/28 Very Toxic: danger of very serious irreversible effects through inhalation and if swallowed.
R39/27 Very Toxic: danger of very serious irreversible effects in contact with skin.
R39/27/28 Very Toxic: danger of very serious irreversible effects in contact with skin and if swallowed.
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R39/28 Very Toxic: danger of very serious irreversible effects if swallowed.
R40 Limited evidence of a carcinogenic effect.
R41 Risk of serious damage to eyes.
R42 May cause sensitisation by inhalation.
R43 May cause sensitisation by skin contact.
R42/43 May cause sensitisation by inhalation and skin contact.
R44 Risk of explosion if heated under confinement.
R45 May cause cancer.
R46 May cause heritable genetic damage.
R48 Danger of serious damage to health by prolonged exposure.
R48/20 Harmful: danger of serious damage to health by prolonged exposure through inhalation.
R48/20/21 Harmful: danger of serious damage to health by prolonged exposure through inhalation and in contact with
skin.
R48/20/21/22 Harmful: danger of serious damage to health by prolonged exposure through inhalation, in contact with skin
and if swallowed.
R48/20/22 Harmful: danger of serious damage to health by prolonged exposure through inhalation and if swallowed.
R48/21 Harmful: danger of serious damage to health by prolonged exposure in contact with skin.
R48/21/22 Harmful: danger of serious damage to health by prolonged exposure in contact with skin and if swallowed.
R48/22 Harmful: danger of serious damage to health by prolonged exposure if swallowed.
R48/23 Toxic: danger of serious damage to health by prolonged exposure through inhalation.
R48/23/24 Toxic: danger of serious damage to health by prolonged exposure through inhalation and in contact with
skin.
R48/23/24/25 Toxic: danger of serious damage to health by prolonged exposure through inhalation, in contact with skin
and if swallowed.
R48/23/25 Toxic: danger of serious damage to health by prolonged exposure through inhalation and if swallowed.
R48/24 Toxic: danger of serious damage to health by prolonged exposure in contact with skin.
R48/24/25 Toxic: danger of serious damage to health by prolonged exposure in contact with skin and if swallowed.
R48/25 Toxic: danger of serious damage to health by prolonged exposure if swallowed.
R49 May cause cancer by inhalation.
R50 Very toxic to aquatic organisms.
R50/53 Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.
R51 Toxic to aquatic organisms.
R51/53 Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.
R52 Harmful to aquatic organisms.
R52/53 Harmful to aquatic organisms, may cause long-term adverse effects in the aquatic environment.
R53 May cause long-term adverse effects in the aquatic environment.
R54 Toxic to flora.
R55 Toxic to fauna.
R56 Toxic to soil organisms.
R57 Toxic to bees.
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R58 May cause long-term adverse effects in the environment.
R59 Dangerous for the ozone layer.
R60 May impair fertility.
R61 May cause harm to the unborn child.
R62 Possible risk of impaired fertility.
R63 Possible risk of harm to the unborn child.
R64 May cause harm to breast-fed babies.
R65 Harmful: may cause lung damage if swallowed.
R66 Repeated exposure may cause skin dryness or cracking.
R67 Vapours may cause drowsiness and dizziness.
R68 Possible risk of irreversible effects.
R68/20 Harmful: possible risk of irreversible effects through inhalation.
R68/20/21 Harmful: possible risk of irreversible effects through inhalation and in contact with skin.
R68/20/21/22 Harmful: possible risk of irreversible effects through inhalation, in contact with skin and if swallowed.
R68/20/22 Harmful: possible risk of irreversible effects through inhalation and if swallowed.
R68/21 Harmful: possible risk of irreversible effects in contact with skin.
R68/21/22 Harmful: possible risk of irreversible effects in contact with skin and if swallowed.
R68/22 Harmful: possible risk of irreversible effects if swallowed.