Bulk Liquid Storage Tank

8/8/2019 Bulk Liquid Storage Tank

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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.



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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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8


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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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.



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.




Closest Private Potable Water Supplies

Abstracting from the Aquifer

Don't Know.




Closest Other Abstractions from the

Aquifer

Don't Know.




Closest Surface Water

Course/Springs/Wetlands

Don't Know.



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


zone

Minor aquifer and

distant from any potable


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


zone

Major\minor aquifer

and nearby potable


Complex drift


zone

Minor aquifer and

distant from any potable


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.


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


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


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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Item


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


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.

Documents

Bulk Liquid Storage Tank