a practical guide to environmental risk assessment for ...infohouse.p2ric.org/ref/16/15252.pdf · a...

A Practical Guide to EnvironmentalRisk Assessmentfor Waste Management Facilities

Simon Pollard, Dave Purchase and Sue Herbert

Guidance Note: 25 8 November 2000

Title: A Practical Guide toEnvironmental Risk Assessmentfor Waste Management Facilities

Guidance Note 25Version: 2

Approval Signature Date

Distribution: Environment Agency & External

Dr Jimi Irwin 8 November 2000

A Practical Guide to Environmental Risk Assessment for Waste Management FacilitiesGuidance Note 25 Version 2

National Centre for Risk Analysis and Options Appraisal Page i

Keywords: waste management licensing, environmental risk assessment

Links to Duties and Powers: Environmental Protection Act Part II, sections 35(3), (4), (5),(8), 36(3), 37 & 42(1); Waste Management Licensing Regulations, regulation 19, Schedule 4,paragraphs 4(1)(a), 6.

Public Domain References: see bibliography

Internal References: see bibliography

Contact Details:Simon Pollard, Risk Analysis Manager, National Centre for Risk Analysis and OptionsAppraisal, Steel House, 11 Tothill Street, London, SW1H 9NF; Tel: 020 7664 6832; Fax: 0207664 6836; email: [email protected]

David Purchase, Regional Waste Licensing Manager, North West Region, P.O. Box 12,Richard Fairclough House, Knutsford Road, Warrington, WA4 1HG; Tel: 07768 276931;Fax: 01925 242209; email: [email protected]

Status: Environment Agency, External

Acknowledgements: The Agency acknowledges contributions from the following in thepreparation of Version 2:

Agency staff:Dave Bliss, Ian Brindley, Karen Byrom, Charlotte Danvers, Bill Darbyshire, Steve Eland,Peter Elliott, Dave Fleming, Jan Gronow, Mike Harget, Jill Leather, Mark Maleham, TonyMarsland, David Parr, Brian Payne, Pandora Rene, Jonathan Smith, Mark Stringer andHoward Thorp.

Industry the Environmental Services Association Risk Assessment Sub-group:Beth Bracewell (Sita), Pat Corker (Aspinwall), Francis Crozier (Entec), Lesley Heaseman(Chair) (M J Carter and Associates), Nick Holmes (ESA), Graham Peacock (Biffa), JonWeetman (Shanks), Chris Young (WRc).

The Agency further acknowledges the contributions and feedback received from Agency staffin the development of the Shell Licensing Kits and training in their use.

This Guidance Note replaces Version 1 (issued as Version 1.1, Consultation Draft forComment, 8 March 1999). The Environment Agency officers, servants or agents accept noliability whatsoever for any loss or damage arising from the interpretation or use ofinformation, or reliance upon the views, contained herein.


National Centre for Risk Analysis and Options Appraisal Page ii

EXECUTIVE SUMMARY

This document provides technical guidance to Environment Agency staff and to applicants onthe practical environmental risk assessment tools that can be used in the waste managementlicensing process to assist in the design and operation of sites to prevent pollution. It shouldbe used alongside the DETR/EA Guidelines for Environmental Risk Assessment andManagement (DETR, Environment Agency and Institute for Environment and Health, 2000),that provide general guidance on the Agencys expectations of risk assessment work. Itsupports the Agencys Licensing Process, the Library of Licence Conditions and WorkingPlan Specifications and the Shell Licensing Kits that have been derived from the Library toapply to specific types of waste management facility. The tools described fit within the tieredapproach to environmental risk assessment which is adopted by the Agency (Figure 1). Theguidance is arranged in the following sections:

1. IntroductionIntroduces the concept and stages of environmental risk assessment. Describes the contextand coverage of the principal guidance documents on environmental risk assessment asapplied to waste management facilities, including this guidance.

2. The approach to risk assessment and risk management.Describes the source-pathway-receptor approach as the basis for risk assessment, and therisk assessment and risk management questions which are being asked and answered at eachtier and stage of the assessment. Explains the relationship between risk assessment and riskmanagement systems. Links this approach to options appraisal and cost benefit assessments,and to other permitting regimes for waste management installations (PPC permitting andLandfill Directive).

3. The use of risk assessment in waste management licensing.Describes the relationship between the tiered approach to risk assessment and risk-basedlicensing, based on the Agencys licensing tools the Licensing Process, the Library and theShell Licensing Kits and the resulting products of the process the licence conditions andthe working plan. Explains what an applicant should provide in terms of a risk assessmentand working plan. Includes an Agency decision flowchart for the use of the Shells.

4. Developing the conceptual model.Explains the importance of good problem definition, and the development of a goodconceptual model as the basis for a risk assessment, and how it is carried out and developedthrough Tier 1, 2 and 3 assessments.

5. Tier 1: Screening of environmental risks.Explains what Tier 1 screening assessment is, based on the source-pathway-receptorapproach, and describes its use in the form of the Shell Risk Assessments which form thebasis of the Shell Licensing Kits. Discusses the use of scoring in the rating and prioritisationof risks and risk management systems.

6. Tiers 2 and 3: Detailed environmental risk assessment.Outlines the types of detailed assessments which may be carried out under Tiers 2 and 3.

The descriptions given of these techniques are not prescriptive, but summarise the generalphilosophy and approach of each technique. Examples of these approaches are given in the


National Centre for Risk Analysis and Options Appraisal Page iii

appendices. The approach described in this guidance allows for flexibility in selection ofspecific risk assessment tools, within the overall good practice framework described. Furtherinformation on the Agencys general approach to environmental risk assessment can be foundin DETR, Environment Agency and Institute for Environment and Health (2000) and thereferences in the bibliography.

Figure 1: Tiered Approach to Environmental Risk Assessment and Management(after DETR, Environment Agency and Institute for Environment and Health (2000)

Problem Formulation

Risk Prioritisation Hazard Identification

Identification ofConsequences

Magnitude of Consequences

Probability of Consequences

Significance of the Risk

** SSttaaggeess wwiitthh eeaacchh tt iieerr ooffRRiisskk AAsssseessssmmeenntt

Economics Technology

Social Issues Management

Risk Management

Tier 1 Risk Screening *

Tier 2 Generic QuantitativeRisk Assessment *

Tier 3 Tailored QuantitativeRisk Assessment *

OOppttiioonnss AApppprraa iissaall

Tiered approaches to riskassessment allow application oftools in proportion to thecomplexity and priority of the risk.They also help in ensuringproblems are properly defined andscoped out prior to the applicationof numerical methods. This is theapproach promoted in the revisedDETR/EA Guidance onEnvironmental Risk assessment andRisk Management (DETR,Environment Agency and Institutefor Environment and Health, 2000).

Collect data & iterateprocesses wherenecessary


National Centre for Risk Analysis and Options Appraisal Page iv

CONTENTS1 INTRODUCTION............................................................................................................1

1.1 What is environmental risk assessment? ..............................................................................................................1

1.2 Scope and Context of this Guide............................................................................................................................1

1.3 Further information and guidance ........................................................................................................................2

2 THE APPROACH TO RISK ASSESSMENT AND RISK MANAGEMENT...........7

2.1 Introduction...............................................................................................................................................................7

2.2 The source-pathway-receptor concept as the basis for risk assessments.....................................................7

2.3 Options appraisal and risk management decisions......................................................................................... 10

2.4 Risk management measures for waste management facilities ....................................................................... 11

2.5 Primary and residual risk management ............................................................................................................ 11

2.6 The need to consider risk management measures for the site as a whole.................................................... 12

2.7 Where do costs and benefits fit in?..................................................................................................................... 12

2.8 Environmental risk assessments for licensing in relation to those for PPC permits and the LandfillDirective............................................................................................................................................................................. 13

3 THE USE OF RISK ASSESSMENT IN WASTE MANAGEMENT LICENSING15

3.1 Risk assessment and waste management regulation ....................................................................................... 15

3.2 Environmental risk assessment questions for waste management licensing: stages, tiers, tools andtechniques.......................................................................................................................................................................... 15

3.3 Waste management licences and risk-based conditions................................................................................. 16

3.4 The Library of Licence Conditions and Shell Licensing Kits ........................................................................ 17

3.5 The tiered approach in relation to the Library and Shells ............................................................................. 18

3.6 What should an applicant provide?.................................................................................................................... 21

3.7 Licence conditions, risk assessments, risk management systems and working plans................................ 21

4 DEVELOPING THE CONCEPTUAL MODEL........................................................23

5 TIER 1: SCREENING OF ENVIRONMENTAL RISKS.........................................27

5.1 Introduction............................................................................................................................................................ 27

5.2 Screening of environmental risks for waste management sites ..................................................................... 27

5.3 Shell Risk Assessments.......................................................................................................................................... 28

5.4 The source of environmental risks................................................................................................................... 29

5.5 Hazardous events and pathways......................................................................................................................... 30

5.6 Environmental receptors...................................................................................................................................... 31

5.7 The environmental risks that are assessed........................................................................................................ 31

5.8 The risk management systems that may be required, and default standards.............................................. 31

5.9 Site-specific variation from the default risk management requirements...................................................... 31

5 . 1 0 Scoring, rating and prioritisation of environmental risks......................................................................... 33

6 TIERS 2 AND 3: DETAILED ENVIRONMENTAL RISK ASSESSMENT...........35


National Centre for Risk Analysis and Options Appraisal Page v

6.1 Detailed quantitative risk assessments............................................................................................................... 35

6.2 Tier 2: Generic Quantitative Risk Assessment ................................................................................................ 37

6.3 Tier 3: Tailored risk assessment........................................................................................................................ 37

6.4 Event and fault tree analysis................................................................................................................................ 38

6.5 The selection of appropriate data for tailored risk assessment..................................................................... 40

7 GLOSSARY....................................................................................................................41

8 BIBLIOGRAPHY..........................................................................................................44

9 APPENDICES ................................................................................................................46

National Centre for Risk Analysis and Options Appraisal Page 1

1 INTRODUCTION

1.1 What is environmental risk assessment?

Risk assessment is a management tool that aids decision-making and which is used widelywithin regulation, business and finance. It involves the separate consideration of thelikelihood and the consequences of an event, for the purposes of making decisions about thenature and significance of any risks, and how best to manage any unacceptable risks. It is anactivity which is familiar to and performed by us all, albeit intuitively. Environmental riskassessment requires an understanding of the source of a hazard to, or from, the environment,the characteristics of an environmental receptor that may be at risk from that hazard, and themeans, or pathway, by which the receptor may be affected by that hazard.

Environmental risk assessment is fundamental to all phases of development of wastemanagement facilities, from the strategic planning level through to the licensing of anindividual facility (see the Environment Agency policy on the location and impact of wastemanagement facilities given in Environment Agency, 2000j). At the strategic level, riskassessment informs decisions about land use, and subsequently underpins assessment of theenvironmental impact associated with the site location that is considered through thedevelopment planning process. In the context of waste management licensing, environmentalrisk assessment is used to enable the operator and the Agency to identify whether and whatrisk management options, or mitigation measures, are required to adequately prevent, control,minimise and/or mitigate the identified risks to the environment from that site. Thesemeasures are normally stipulated as licence conditions or in the working plan.

Environmental risk assessment is essential for all waste management facilities and the riskinformation gained will be key to regulatory decisions made by the Agency and others.

1.2 Scope and Context of this Guide

This Guide describes the current Agency approach and supporting tools for environmentalrisk assessment in waste management licensing. It explains the use of some practical toolsthat will assist licence applicants and Agency officers in carrying out and reviewing riskassessments, so that they can identify and define the engineered and operating systems thatwill be necessary and appropriate to ensure that any unacceptable risks are managedeffectively.

The Guide does not represent a specification for work, nor does it aim to be prescriptive or toset out how standards themselves are defined by the Agency. It should be used alongsideother Agency licensing tools and guidance, taking into account relevant statutory and bestpractice guidance, to inform the decision-making process. Applicants have flexibility in theirselection of specific techniques and professional judgement will be required of Agency staffand applicants as to what level of detail is required. Guidance on this is included.

Whilst this Guide focuses on risk assessment for the licensing phase of development of awaste management facility, readers must bear in mind that, in the same way that licensing isnot carried out in isolation from the outcome of the planning process, risk assessment forlicensing should not be divorced from earlier risk assessments carried out for planningpurposes. The principles and approach to risk assessment, described in this Guide, areequally applicable to risk assessment at the planning phase, although the level of detail of a



risk assessment required at the licensing phase will often be greater. Risk assessment is aniterative, developing activity, and that carried out for licensing purposes should always buildon and take account of earlier risk assessment findings.

Table 1, based on that included in the Environment Agency policy on the location and impactof waste management facilities (Environment Agency, 2000j), provides a brief overview ofthe level of risk assessment typically required for the different phases of development of awaste management facility. This table is not intended to be prescriptive, but to indicate howthe requirements of risk assessment change, and increase in detail, through the process ofplanning and developing a facility. Figure 2 develops this further to show that the focus ofthe risk assessment work (or effort) changes through these development phases from themacro scale where the interest is in land use and major issues such as site location,fundamental design principles, to the micro scale, where the effort is spent on ensuring thatdetailed design and operational matters are adequate.

1.3 Further information and guidance

The Department of the Environment, Transport and the Regions (DETR) and theEnvironment Agency have produced a range of guidance to support the use of environmentalrisk assessment, both in general and also with specific application to waste managementregulation. These will be of assistance to users of this document. The context and coverageof some of the principal documents is shown in Figure 3. The following documents areparticularly noted.

For those unfamiliar with the practical aspects and basic terminology of environmentalrisk assessment, the Environment Agency has produced a general document IntroducingEnvironmental Risk Assessment (Environment Agency, 2000a).

Information and general guidance on the tiered approach to environmental riskassessment and the practical considerations involved can be found in Guidelines forEnvironmental Risk Assessment and Risk Management (DETR, Environment Agencyand Institute for Environment and Health, 2000). This Guide adopts and supports theprinciples described in the Guidelines.

Guidance on risk assessment requirements for planning purposes is being developed bythe Environment Agency (e.g. Environment Agency, 2000g).

With respect to the specific requirements of Regulation 15 of the Waste ManagementLicensing Regulations 1994 (assessment of the impact on groundwater), the Agency hasissued separate guidance (Environment Agency 1999a).



Table 1 : Overview of waste management facility development phases and environmental risk assessment

D E V E L O P M E N T P H A S E KEY ISSUESCONSIDERED

LEVEL OF RISK ASSESSMENT 1 ASSESSMENT TOOLS

PHASE 1:Strategic planning, e.g.: Waste local plans Mineral local plans

Site location Basic function (e.g.

broad types of waste,overall capacity)

Risk screening (Identify major hazards andreceptors)

Maps of location of major and minor aquifers(vulnerability maps) eventually locations ofgroundwater bodies under the WaterFramework Directive;

Catchment protection zones (e.g. GroundwaterSource Protection Zone 3, Dee catchment);

Floodplain maps; Statutory conservation zones (SSSI etc).

PHASE 2A:Pre-planning assessments scoping and screeningassessments for EnvironmentalImpact Assessment Regulations.

Fundamental elements ofdesign and operation.

Risk screening (Identify all hazards andreceptors)

As above, but all groundwater protectionzones, mapped conservation areas etc.

Scoping guidance.

PHASE 2B:Planning applications 2;and Stage 1 PPC applications(where appropriate)

Operational principles, sitelayout, major constructionelements e.g. type of landfilllining. Initial design withoutbenefit of planningconditions.

Tiered risk assessment on major elementsof design, construction and operation.(Assess all pathways and impacts)

Site specific assessment site investigations,local mapping etc.

Risk assessment guidance and tools (e.g.LandSim)

PHASE 3:Environmental authorisations 2;e.g. Waste management sitelicence, IPC, PPC

Detailed design taking intoaccount planning conditions,formal feedback fromAgency etc.

Review and/or identify all hazards andreceptors

Tiered risk assessment on detaileddesign, construction and operation.(Assess all pathways and impacts)

Site specific assessment, as above. Risk assessment for waste management

licensing (this guidance, Shell RiskAssessments and, for example, LandSim).



Notes:1. See DETR, Environment Agency and Institute for Environment & Health, 2000.2. Planning applications and environmental authorisations may be progressed in parallel.



StrategicPlanning

Figure 2: Risk Assessment Effort related to Waste Management Facility DevelopmentPhases

ScopingAssessmentTier 1

Tier 2

Tier 3

Licensing

PlanningApplication

RiskAssessment

Scale of Analysis

WasteManagementFacilityDevelopmentPhases

STRATEGIC PLANNING

Legend:

Scale: Macro e.g. Site location, basic function Intermediate e.g. Site layout, major construction elements Micro e.g. Material specifications, operation details

T3

T2

T1

Scale

Mac

ro

Mic

ro

LICENSING

T3

T2

T1

Scale

Mac

ro

Mic

ro

PLANNING

Macro Micro

Mac

ro

Mic

roScale

T3

T2

T1

Risk Assessment Effort

Tie

r

Intermediate



Figure 3: Context and coverage of principal guidance documents on environmentalrisk assessment as applied to waste management licensing

DETR, EnvironmentAgency & Institute forEnvironment andHealth, 2000. Guidanceon Environmental RiskAssessment and RiskManagement.

EnvironmentAgency, 2000g (inpreparation). ScopingGuidance on theEnvironmentalImpact Assessmentof Projects.

EnvironmentAgency, 2000a.IntroducingEnvironmentalRisk Assessment .

Genericguidance onprinciples ofenvironmentalrisk assessmentfor publicdomainenvironmentalrisk assessments

EnvironmentAgency, 2000.A Practical Guideto EnvironmentalRisk Assessmentfor WasteManagementFacilities (GN25)(this guidance).

Environment Agency,1998. InterimFramework Policy forLandfill Engineering.

Environment Agency,1999. Interim InternalGuidance onInterpretation andApplication ofRegulation 15.

Department of theEnvironment,1994a. Circular11/94;Department of theEnvironment,1995. W asteManagement Paper26B.

Leafletintroducinggeneralprinciples fornon-specialists

Environment Agency, 1999b &2000c. Library of Licence Conditionsand Working Plan Specifications.

Site-specific riskassessment forwaste managementsite(Not guidance.Document suppliedto Agency in supportof application, or byAgency in supportof Agencymodification)

Translation ofgeneral principlesto wastemanagementlicensing

Guidance on the use ofsimple risk assessmenttemplates for standard sites

Simple riskassessmenttemplates forstandard sitecategories

Site-specific risk assessmentfor waste management site:operators document, whichmay be produced fromagreed template, or modifiedwith more detailedassessment

Environment Agency,2000d. Shell RiskLicensing Kits: Guidanceon their Derivation,Content and Use.

Environment Agency,2000d. IndividualShell Risk Assessmentpacks for selected sitecategories from therange A1-A25.

DETR statutoryguidancerelevant to riskassessment

Guidance onspecific riskassessmentssupporting theuse of theLibrary

Frameworkandguidance forapplicationof riskassessmentin use ofLibrary

Guidance onrisk assessmentrequirementsfor planningpurposes



2 THE APPROACH TO RISK ASSESSMENT AND RISK MANAGEMENT

2.1 Introduction

Environmental risk assessment and risk management typically involves answers being soughtto the following questions:

What environmental hazards are present and what are their properties? How might the receptors become exposed to the hazards and what is the probability and

scale of exposure? Given exposure occurs at the above probability and magnitude, what is the probability

and scale of harm? How significant is the risk and what are the uncertainties? What needs to be done to prevent, control or minimise the risks?

The Agency adopts a tiered approach to answering these questions, in accordance with goodpractice, which is described in its general guidance on environmental risk assessment andmanagement (DETR, Environment Agency and Institute for Environment and Health, 2000).This is outlined in Figure 1, and indicates that assessment and appraisal effort should betargeted where risks or uncertainties are high. Early risk screening and prioritisation avoidsunnecessary detail and allows the level of approach to be matched to the needs of theproblem. If the risk management decision cannot be made based on an initial screeningassessment, then more detailed approaches are used, focusing on the key risks identified. Theemphasis is on:

i) understanding the environmental setting;ii) using simple, qualitative tools; andiii) applying greater levels of sophistication according to need.

However, it is important that all risk assessments, whether simple or complex, are carried outin a robust, systematic and transparent manner.

2.2 The source-pathway-receptor concept as the basis for risk assessments

Fundamental to the good practice framework for risk assessment shown in Figure 1 is thesource-pathway-receptor approach. For a risk to exist, there must be an identified orplausible relationship between the three individual components of:

source i.e. the hazardous substance or material receptor i.e. the entity (e.g. human, water body, ecosystem, building, etc) that is

vulnerable to the adverse effects of the hazardous substance or material pathway i.e. the mechanism by which the receptor and source can come into contact

(e.g. by a hazardous event or action on site giving rise to a release of the hazardoussubstance or material to atmosphere or to ground).

The source for waste management facilities is defined by the hazardous properties of thewaste types and operations to which they will be subjected on the proposed site. (It may alsoinclude the events which lead to the hazards associated with those wastes and/or operationsbeing transferred into the environment, although, as used in this guidance, it is more



appropriate to link such hazardous events with the pathways by which the hazards aretransferred.)

The environmental receptors (or targets) are those entities which are liable to be adverselyaffected by the identified hazards transferred from the defined source into the environmentby the identified pathways. These include, but are not necessarily restricted to: People outside the site boundary. (People within the site boundary are only considered

where they may be trespassers or others who have gained unauthorised access sitesecurity requirements are imposed to prevent this situation occurring. People who arelegitimately on site - including site staff and other people who are authorised or doingother legitimate business - are covered specifically by the Health and Safety at Work Act1974 and are not considered in the environmental risk assessment);

Properties outside the site boundary, including public and private property and placeswhere the public have access this may also include livestock or other animals which arekept (rather than wild) outside the site boundary (or within the site boundary);

Ecosystems, especially habitats designated in accordance with the Habitats Directive, andother designated sites;

Surface water in the vicinity of the site; Groundwater in the vicinity of the site; Atmosphere, which is a receptor in regard to the risk of global warming.

The pathways for a defined source of environmental hazards are the means by which theidentified hazards are transferred into the environment, and thence to any defined receptorsin the environment. Hazardous events and the pathways by which the resulting hazardsare transferred into the environment are intimately linked. They include the followingenvironmental pathways: Direct emissions of heat and shock due to fire or explosion; Releases of polluting emissions by one or more of the following routes:

- air (or atmosphere) as pathway (it may also be a receptor for certain risks seebelow);

- ground (including via services);- water (surface water and groundwater are receptors in their own right see below);

Other vectors for environmental hazards:- dust- pests;- scavengers;- litter;- noise.

If humans (or animals) are exposed to hazardous substances or emissions via one or more ofthe above environmental pathways, harm to their health may occur through a number ofexposure pathways. Typically these may include: inhalation or ingestion of, or dermalcontact with, hazardous substances; and the direct effects of heat and shock in the case offires or explosions. Humans may also suffer harmful effects on health through seriousdetriment to the amenity of their locality.

The type and magnitude of the harmful effects will depend upon the dose received, theparticular dose-response relationships for those hazardous substances, and other more



specific factors such as the sensitivities of the individuals. The resulting effects on healthmay be direct or indirect, acute or chronic.

The assessment of the risks of harm from exposures to hazardous substances and emissions isvery complex and subject to wide variability between individuals. It is not specificallyconsidered except in some more detailed and complex Tier 2 and Tier 3 risk assessments,although it may form the basis of certain environmental quality criteria or targets. In Tier 1and many Tier 2 and 3 assessments, it is sufficient for the assessment to identify whether ornot a significant exposure of identified human or animal receptors is likely to occur, in orderto decide whether or not risk management measures need to be provided.

Box 1 provides an example of the source-pathway-receptor approach for a landfill generatinglandfill gas.

Box 1: Example of source-pathway-receptor approach.

Consider the case of methane gas emanating from an active landfill site. Methane representsan explosion hazard between certain defined concentrations in confined spaces. Methaneemanating from the source (the active landfill site) at sufficient pressure poses a high risk ofharm (injury, loss of life and damage to property) to receptors in the vicinity of the site(persons and buildings) where the likelihood (or probability) of concentrations building up tothe lower explosive limit is high, due to the presence of suitable environmental pathways forlandfill gas migration and ingress into buildings (such as permeable ground strata ormanmade drains, conduits, etc).

The source in this example is the biodegradable, methanogenic waste within the landfillsite, which is generating methane gas. The potential pathways are the permeable groundstrata, or manmade drains, conduits, etc, around the landfill site. The potential receptors arethe buildings and their occupants in the vicinity of the site.

If the risk assessment identifies that the risk exists from methane to nearby housing, theAgency will stipulate in the licence conditions that the operator provides and maintainsspecified systems to manage the identified risks from landfill gas emanating from the site; forexample, that they:

a) provide, operate and maintain a landfill gas management system that meets defineddesign and performance standards (for example, this may include a membrane aroundthe waste to contain landfill gases, a landfill gas collection system, and a landfill gasflaring or energy recovery system); and

b) provide monitoring points and boreholes for landfill gas around the site in suchpositions that landfill gas migrating through the ground strata from the site can bedetected; and

c) carry out a defined programme of monitoring landfill gas at those monitoring points,including analysis and reporting of the results and the carrying out of defined actionsif the measured levels of landfill gas exceed defined values.

The operator will then provide the necessary information on the systems that they willprovide and maintain to meet these requirements, in their working plan and other supportingdocumentation.



If it can be shown for a particular site, that there is no plausible connection or pathwaybetween potential releases from a specified hazardous source (e.g. a specified treatmentoperation being carried out on specified wastes with one or more environmentally hazardousproperties) and environmental receptors which are known or expected to exist in the vicinityof the site, then the situation cannot be considered to present a risk as there is no realisticsource-pathway-receptor relationship.

A decision that a realistic source-pathway-receptor relationship exists does not always meanthat there must be firm evidence of the presence of all three components: source, pathway andreceptor. However, it must be evident that the source has hazardous properties that have thepotential to adversely affect the receptors in question. Furthermore, the presence of thereceptors must be proven or be a realistic possibility. It may not always be possible to provethe presence of a pathway linking the two, but again this must be a realistic likelihood ratherthan a theoretical possibility.

In making decisions about source-pathway-receptor relationships for waste managementfacilities, the Agency will give consideration to being precautionary in the light of expectedchanges and events over the lifetime of the facility, which may result in the nature of therelationship changing with time. Decisions will be made on a site-specific basis, bearing inmind the need to be both proportionate and precautionary.

If a plausible source-pathway-receptor relationship is identified for a particular site, this willnormally be taken by the Agency to demonstrate the need for appropriate risk managementmeasures to prevent the anticipated risks being realised. In many cases, robust decisionsabout the presence of a plausible source-pathway-receptor relationship will be sufficient fordecision-making about the need for risk management measures. It may not be necessary,desirable or cost-effective to resort to more detailed quantitative assessments of theprobability and scale of risks involved, except in cases (such as the design of landfill linersystems) where it may be necessary to enable detailed design of the risk managementmeasures.

This is the basis of the tiered approach to risk assessment shown in Figure 1, that the level ofeffort put into assessing risk reflects the priority of the risk and how any risks would be dealtwith. For many waste management facilities, it will be more appropriate to put most effortinto design and management of the facility, provided that robust initial decisions are madeabout source-pathway-receptor relationships. Guidance on Tier 1 risk assessments (and theuse of the Agencys Tier 1 Shell Risk Assessment tools) is given in Chapter 5, and on Tier 2and Tier 3 assessments in Chapter 6.

2.3 Options appraisal and risk management decisions

The purpose of carrying out an environmental risk assessment is to inform a risk managementdecision; that is, to determine what risk management measures need to be taken to preventand control the identified risks.

There may be more than one way of managing the identified risks, and the decision as towhich is the best option may need to be informed by an appraisal of their relative costs andbenefits. Waste licensing decisions include a qualitative consideration of likely costs and



benefits through the application of the test of reasonableness, and this is discussed in moredetail in section 2.7.

The applicant or operator will normally have assessed the different design options for a givenfacility at the stage of conceptual/outline design, prior to their licence application. Thedecision on whether the proposed waste management facility represents the best practicableenvironmental option (BPEO) will generally be made at the planning stage. Where a detailedoptions appraisal is required at this stage it may need to take into account relevant factors oftechnology, economics, social issues and management. This document does not includeguidance on such detailed options appraisals, since these are generally not required for thepurpose of preparing licence conditions.

If there are circumstances where a detailed options appraisal is required at the licensing ormodifications stage, then specialist guidance should be sought. As with the tiered approachto risk assessment, the approach taken should be proportional to the outcome, meaning thatthe resources required to undertake the options appraisal should not be disproportionate to thecosts and benefits of the decision.

2.4 Risk management measures for waste management facilities

Detailed guidance on the risk management measures covered by specific licence conditionsand working plan specifications is given in the Library of Licence Conditions and WorkingPlan Specifications (Environment Agency, 2000c) and in the Shell Licensing Kits which arederived from it (Environment Agency, 2000 d). (These are described in section 3.4.)

The complexity of the measures needed will depend upon the type and level of risks that thewaste management operations in question present to the environment. The measures neededto prevent and control the risks may be relatively simple, such as operational proceduresrequiring simple actions and documentation, or relatively complex, such as engineeredsystems requiring fully documented and quality assured stages of design, construction, testingand validation, operation and maintenance.

An example of the former would be waste acceptance and control procedures for a transferstation handling inert, non-hazardous or low hazard, non-special wastes. An example of thelatter would be the systems underlying the provision of an engineered site liner for a landfill,or of a groundwater monitoring programme for a landfill. These will place different levels ofdemand on supporting systems such as record-keeping, and the training and competence ofsite staff.

If the risk management provisions (simple or complex) are to be effective, they must bespecified and carried out to an appropriate and auditable standard. Risk managementprovisions to prevent emissions to the environment will usually consist of a combination ofoperational procedures and controls, engineered containment of emissions, and, as relevantand appropriate, monitoring of emissions with actions to control and minimise any emissionsthat do occur.

2.5 Primary and residual risk management

It is important to recognise that, where risk management measures are provided, thereremains a risk that these will fail to perform to the required performance standard. This is



referred to in the Library and Shell risk assessment approaches as the residual risk; that is,the risk to the environment posed by the identified hazard, taking into account the primaryrisk management measures that will be provided.

Such failures can occur due to faults in design, installation, and operation (includingmaintenance). The causes of faults and failures may include failures in hardware, software,and procedures; and will often include an element of human error. It is essential thatprovision be made to minimise the likelihood of residual risks so as to ensure that therequired standard of environmental protection is realised throughout the life of the site. Thenecessary residual risk management should be provided so as to prevent such failuresgiving rise to significant functional failure of the primary risk management system underconsideration. Typically, this will be provided by the following measures: during the design stage, through the site investigations and risk assessments supporting

the design process, the use of recognised design standards, and adherence to a formaliseddesign quality assurance process;

during the installation stage, through adherence to a formalised construction qualityassurance process, supported where appropriate by a testing/commissioning stage;

during the operational stage, through adherence to documented operational proceduresand maintenance programmes, supported by:- monitoring of the process performance and emissions; and- documented procedures for dealing with deviations from defined performance and

emission standards; and- periodic reviews of performance against the environmental emission standards and of

the environmental risk management systems for the site.

2.6 The need to consider risk management measures for the site as a whole

It will be evident from the preceding discussion that risk management measures, both for thesite and for particular operations, should be regarded as an integrated whole. A change to onepart or element of the system, such as the design standards, or the quality and content ofrecord-keeping, or the training and competence of staff, will potentially change theeffectiveness or performance of the risk management system as a whole. This means that anyproposed changes to any part of a risk management system should be assessed for their effecton the overall performance of the risk management measures, to ensure that the necessarystandards of environmental protection are maintained for that system and for the overall siteoperations.

This is the reason that the licence conditions set a requirement for proposed changes to theworking plan to be supported by a review of the relevant risk assessments, and to be pre-notified to and, where necessary, approved by the Agency before implementation.

2.7 Where do costs and benefits fit in?

Under Section 39 of the Environment Act, the Agency has a duty to take account of likelycosts and benefits in deciding whether or not to exercise its powers, and in deciding how toexercise those powers. It is important to note that this duty:

i) does not supersede the Agencys obligations to discharge specific duties, comply withlegal requirements or meet objectives; and



ii) does not require the consideration of costs and benefits to involve their quantification ormoneterisation.

In its waste licensing decisions, the Agency has a duty to prevent pollution of theenvironment, harm to human health and serious detriment to amenities of the locality.

Licence conditions prepared using the Library or Shells are aimed at satisfying this duty andmeeting the statutory guidance (Department of the Environment, 1994a) which states thatconditions should be: proportionate in their requirements to the risks involved and the benefits to be obtained; goal-based, having defined objectives and specified standards and, where appropriate,

specifying the means to their fulfilment;but should not: serve as an end in themselves; be over-prescriptive; or impose an unjustifiable or disproportionate burden on the licence holder, especially small

businesses.

Risk management offers the benefit of risk reduction, so risks can be characterised withreference to the costs of implementing measures to mitigate them. A level of judgement onthe test of reasonableness is therefore required on the part of the regulator when preparinglicence conditions, and also when preparing subsequent licence modifications.

2.8 Environmental risk assessments for licensing in relation to those for PPC permits and theLandfill Directive

The Pollution Prevention and Control (England and Wales) Regulations 2000 (SI 2000 No.1973) came into force on 1 August 2000. A number of types of waste managementinstallations, as defined in Chapter 5 of Schedule 1 of the Regulations, will need to beregulated under the PPC regime instead of the waste management licensing regime. Existinglicences for these types of installations will be replaced by PPC permits in accordance withthe programme defined in Schedule 3 to the Regulations.

As such, these installations will then be subject to assessments of whether they satisfy therequirements of the best available techniques (or BAT) criterion, as defined in Regulation3. The Agency is currently developing guidance on an assessment methodology (the E2guidance and methodology) for this purpose. This will be developed, so far as practicable, tobe consistent with the relevant related methodologies under planning legislation (EIAs) andthe Control of Major Hazards (COMAH) Regulations. It will incorporate:

i) a stage to assess and compare options, to determine the best practicable environmentaloption (BPEO) for a proposed installation, consistent with the planning stage; and

ii) an environmental impact assessment stage to determine, for those options where thetechnical standards for BAT are not defined or else an alternative is sought, whether thepreferred option satisfies the BAT requirement.

Consistent with the Agencys tiered approach and the approach for waste managementlicensing covered by this guidance, the PPC E2 approach will incorporate screeningassessments as a basis, although it may be that, due to the nature of the requirements under



the PPC regime, this will lead to a greater degree of use of detailed technical assessments ofthe Tier 2 and Tier 3 type. This is not likely to significantly affect the guidance given in thisdocument for those sites which remain within the waste management licensing regime.

The EU Landfill Directive comes into force on 16 July 2001, and is expected to be introducedin England and Wales through the PPC regime. All landfills will be required to adhere tonew requirements regarding their design and operation, and over a period of time all landfillwaste management licences will be replaced with PPC permits that comply with the LandfillDirective requirements. The Agency is developing further guidance on risk assessmentrequirements for landfills under the Landfill Directive and this document will be revised, asappropriate, in due course.



3 THE USE OF RISK ASSESSMENT IN WASTE MANAGEMENTLICENSING

3.1 Risk assessment and waste management regulation

The siting, operation and decommissioning of waste management facilities carries certainrisks that are assessed at various times within a facilitys life, from design throughconstruction and operation to decommissioning and licence surrender. Environmental riskassessment can be applied at the following stages: at the strategic planning, pre-planning and planning stages (through submission of

environmental impact assessments and environmental statement s, including riskassessments; if detailed options appraisals are necessary they will usually be carried out atthese stages);

during the process of waste management licensing (through the use of the Library andShells, and including requirements for a Regulation 15 assessment) (this process may becarried out in parallel to the planning application);

during the site supervision stage (through the use of the Agency Site InspectionMethodology and the use of the Operator Pollution Risk Appraisal (OPRA for Waste)technique for prioritising inspections on a risk assessment basis these arecomplementary to and consistent with the Library and Shell risk assessment tools)

prior to modification of the licence or amendment of the working plan, resulting fromchanges to operation (through the use of the Library and Shells, and includingrequirements for a Regulation 15 assessment); and

prior to site completion/closure and licence surrender (through the Licence Surrenderprocess, using the supporting risk assessment guidance for that process).

Procedural and technical guidance is provided by the various waste management papers andAgency documents, to which readers are referred. The scope and methodology of the riskassessment will be dictated by the specific requirements of each stage and the purpose forwhich the assessment is being carried out. While it should not automatically be presumed thata risk assessment undertaken for one stage will necessarily be adequate for another, there willusually be a degree of overlap, and opportunities should be taken to make use of valid andreliable assessments of risks which have been produced at earlier stages and which are ofrelevance to waste management licensing. In particular, the potential to screen risks duringany environmental impact assessment (EIA) carried out at the planning stage should beregarded as a valuable opportunity to undertake work of relevance to licensing the site.Similar opportunities should be sought through the preparation of site-specific riskassessments supporting a Regulation 15 assessment for facilities where List I and IIsubstances are of relevance.

3.2 Environmental risk assessment questions for waste management licensing: stages, tiers, toolsand techniques

Environmental risk assessment for waste management licensing should not be carried outeither for its own sake or in isolation, but in order to assist the making of risk managementdecisions in a cost-effective manner. The practical objective is to provide answers to thequestions of:



i) what risk management measures are required for a particular site; and henceii) what needs to be specified in the licence conditions and described in the working plan.

Appendix 1 provides a breakdown of these into the following questions:

A. What is the nature of the site (including the waste management operations) and its environmentalsetting?

B. Is there a risk to the environment from the waste management operations on this site?

B1. What hazards are present and what are their properties?

B2: What are the potential environmental consequences that may arise from the identified hazards?

B3. What is the magnitude of the consequences for the identified potential receptors?

B4. How might the receptors become exposed to the hazards?

B5. What is the probability of the hazard occurring?

B6: What is the probability of the receptors becoming exposed to the hazard?

B7: What is the probability of harm resulting from exposure to the hazard?

B8. How significant is the risk?

B9. What are the uncertainties? (Is a more detailed risk assessment needed?)

C. What are the options for management of the identified risks?

D. What needs to be done to minimise the environmental risks?

E. Does the risk assessment need to be reviewed or revised?

The table in Appendix 1 indicates how, in addressing these questions:a) the tiered approach to risk assessment and the identification of appropriate risk

management measures would be applied at Phase 3 (Environmental authorisation: wastemanagement licensing see Table 1); and

b) hazard identification, risk assessment and identification of appropriate risk managementmeasures would be carried out using the tools and techniques appropriate for wastemanagement licensing,

The table includes an example of how a Shell Risk Assessment approach would be applied(as explained in the following sections and Chapter 5) in the case of a waste transfer stationhandling household, industrial and commercial wastes, for the particular hazard of wasteswhich are likely to produce emissions of dust to atmosphere.

3.3 Waste management licences and risk-based conditions

A waste management licence is issued with conditions attached. The conditions relate to theactivities the licence authorises; and the precautions to be taken and/or works to be carriedout in connection with, or in consequence of those activities. Requirements may therefore be



imposed in the licence, to be complied with before the activities authorised by the licencehave begun, or after they have ceased.

The objective of a waste management licence is to ensure that the licensed facility does notcause either pollution of the environment or harm to human health and does not becomeseriously detrimental to the amenity of the locality. The Agency aims to set licenceconditions which specify (to the level of detail necessary to meet this objective) the riskmanagement provisions and the standards they must meet. It is a basic requirement of wastemanagement licensing that licence conditions should be specific to the site in question. Thisdoes not obviate the use of templates, or the use of benchmark requirements for typical sitesas default standards, provided that the process is supported by a risk assessment of thesources, pathways and receptors of environmental risk for the site in question in relation to itsspecific environment.

Use of the Library and Shell tools enables the Agency to set licence conditions based on theassessed environmental risks at the specific site in question. The licence conditions willrequire an appropriate type and level of engineered and operational systems to be providedthat will prevent, control and minimise those risks to acceptable standards.

3.4 The Library of Licence Conditions and Shell Licensing Kits

The Library provides tools for: the production of risk-based site-specific licence conditions, based on the use of Library

Condition Templates; and the production and assessment of working plans, based on the use of Working Plan

Specifications.

Licences drafted using the Library and this guidance contain a customised set of conditionsreflecting the environmental risks identified from a site-specific risk assessment. However,the Library is a complex tool applicable to the full range of waste management operationsthat span the whole spectrum of environmental risk. The work involved in preparing,assessing, consulting and finalising the site-specific risk assessment, the working plan and thelicence conditions, can be complex and demanding on resources.

As experience of using the Library and the Licensing Process has grown it has becomeapparent that there are opportunities for streamlining the process. As a consequence ShellLicensing Kits are being developed and issued in order to provide optional starter packs fortypical sites in certain categories falling within the Agencys site classification system (A1 toA24). This classification is currently used by the Agency for waste management licensingprocess records and Agency OPMs, for the site inspection methodology and OPRA forWaste, and for waste strategy site classifications.

Each Shell Licensing Kit is intended to stand alone, without recourse to the Library or itssupporting guidance unless necessary for particular issues. Each kit includes, specific to thecategory of site covered: Guidance notes on the derivation, content and use of the Shell Licensing Kit. A Shell Risk Assessment pack, based on a generic Tier 1 screening risk assessment for a

typical site in that category, which is used by the applicant to produce a risk assessment



which is specific to their proposed site, and which identifies the risk managementprovisions that will be required and will be described in the working plan. (The structureof the Shell Risk Assessment is discussed in more detail in Section 5.)

A specification of the information needed in the working plan for a typical site in thatcategory (based on the Shell Risk Assessment), which is used by the applicant to producethe site-specific working plan, describing the risk management systems that will beprovided on the basis of the site-specific risk assessment.

A template of the licence conditions for a typical site in that category (derived from therelevant Library condition templates), which is used by the Agency to prepare the site-specific licence conditions, taking into account the applicants site-specific riskassessment and working plan.

The Shell approach permits a degree of flexibility in how the specified standards can bedelivered. In producing site-specific conditions, variations from the shell licence templatecan be accommodated provided that they are justified on the basis of the site-specific riskassessment and recorded in the audit trail documentation. This will provide the necessarysupport for the resulting site-specific licence.

Each site/application will still require individual decisions to be made specifically in respectof it. However, properly used, shell licensing kits will enable significant streamlining of therisk assessment and licence drafting processes. They will also assist in ensuring thatoperating standards required for sites of the same type are consistent, whilst still allowinglicences to reflect site-specific differences, e.g. in risk management requirements.

3.5 The tiered approach in relation to the Library and Shells

The Library of Licence Conditions includes an Index of Library Conditions, which provides atabular framework, based on the type of facility and the waste management operations, foridentifying: the Library Condition templates which will need to be included in the licence; and for

risk-based conditions the risk management provisions which the condition will cover in its requirements; and the level of risk assessment which is required for the site.

Application of the Library risk assessment framework allows for the fact that acomprehensive risk assessment for any single waste site may require more than one tier ofapproach, according to the issues under study. This allows for an increasing focus on thoseaspects of the facility that present a higher risk and may require more detailed assessment.The framework does not prescribe the risk assessment tools that should be used within eachtier, but does suggest the applicability of Tier 1-type screening tools, and more detailed Tier2-type generic and Tier 3-type tailored risk assessments based on quantified modellingtechniques (refer to Figures 1 and 2). The framework indicates a level of risk assessment thatwould normally be required but it is recognised that site-specific issues may override andplace more onerous requirements on specific installations. Application of individual riskassessment tools within the overall framework is at the discretion of the applicant.

Figure 4 shows how the use of the Library and Shell Kits fits into the Agencys tieredapproach to risk assessment (as outlined in Figure 1). The Agency decision process for usingShell Licensing Kits in processing an application is shown in the flowchart in Figure 5.



Figure 4: Tiered Environmental Risk Assessment Approach applied toWaste Management Licensing

Pre-application tools:Development of conceptual model, and scoping of site design,operation, & environment (some of this will have been carriedout during the statutory planning process)

Tier 1: Risk screening assessment(using Shell Risk Assessment pack where available)

Tier 2: Generic quantitative RA

Tier 3:Tailored quantitative RA

Use of Shell Licensing Kit tools:Shell Licence Template;Shell Working Plan;Shell Financial ProvisionAssessment;Shell Audit Trail.

Risk assessment outcome: Site-specific risk assessment

Need tocompare riskmanagementoptions

Complex risks

Iteration andreview of riskassessment orriskmanagementstandards,whererequired

Use of Library tools:Licence Condition Templates;Working Plan Specifications ;Financial ProvisionAssessment;Library Audit Trail.

Site-specificvariations,whererequired

Review of sitedesign andoperation, wherenecessary

Licence and working plan preparation output:Site-specific: Risk management systems;

Working plan;Licence conditions;Financial provision assessment;Licence conditions audit trail.

Risk scoring,ranking &

prioritisation(see section 5.10)

Default riskmanagement standards

Deviations from ShellRisk Assessment; &/orneed for detailedquantitative assessment

Risk assessment tools

Tailored riskmanagement standards

Ranked riskmanagementoptions

Ranked riskmanagementoptions



2 Agency DecisionsPre-application

discussions Has a Shell Kit been issued tocover this type of site? Use Library of Licence Conditions &

supporting guidanceFollow full process for use of Library

Does the applicant/operator wantto follow the Shell Licensing Kitfor this application?

Yes

No

Yes

No

No

Assessment ofapplication Shell

Working Plan

Provide applicant with copy ofappropriate Kit andexplain its use

Yes

Does the risk assessmentcompleted by theapplicant/operator (Section 2 ofthe pack) fit the site and proposedoperations?

Identify relevant deviations fromfit;

As appropriate (see guidance) eithercarry out or require operator to carryout risk assessment to necessary levelof detail

Assessment ofapplication ShellRisk Assessment

pack

Do the risk management systemstandards accepted or proposed bythe applicant/operator (Section 2 ofthe pack) provide the necessarylevel of environmental protection?

Identify relevant site-specificstandards;

As appropriate (see guidance) eitherprovide or require operator to providejustification for site-specific standard

No

Yes

Does the working plan provide thenecessary information in thenecessary form?

No

Yes

Identify necessary amendments; Require operator to provide

amended working plan section(s)

Do the Shell licence conditionsrequire site-specific variations(other than the standard inserts)?

Drafting of licenceconditions ShellLicence Template

Identify necessary variations; Carry out justified amendments; Use Library Condition Templates

for any justified additional conditions; Record changes in audit trail

Finalising licenceconditions Shell

Audit Trail

Yes

Finalise and quality assure licenceconditions, and complete audittrail

No

Assessing financialprovision Shell

Financial ProvisionAssessment

Agency Actions

Completion of the following actionsshould, subject to satisfactoryoutcome, be followed by returning tothe Decision chain

Do the applicants financialprovisions give the necessary levelof cover?

Application received

Yes

No

Identify necessary amendments; Require operator to provide

amended financial provision

Process financial provision

Figure 5: Decision flowchart for the use of Shell Licensing Kits in applications



3.6 What should an applicant provide?

The Agency requires a specific risk assessment to be submitted for all applications for awaste management licence. This must be developed according to the principles and goodpractice set out in this guidance and must be site-specific.

The Agency expects applicants will wish to work through the tiered approach outlined inFigures 1 and 4, using the Library risk assessment framework or, where a Shell Licensing Kitis available, the relevant Shell Risk Assessment tool. It is expected that risk assessmentsundertaken in support of Environmental Impact Assessments (EIAs) and the relevantplanning application will be used to inform this process, where they have been carried out.

The degree of sophistication of the risk assessment should reflect the particular conditions ofthe site. However, all environmental risk assessments should be based upon reasonablescenarios, data and assumptions. The development of a clear conceptual model (see Section4) is critical to the analysis.

Tier 1 risk screening assessments may be sufficient where these give a clear demonstration ofthe anticipated level of risk and that the proposed risk management provisions are fit forpurpose, giving the required standard of environmental protection (see Section 5). This mayinclude, where justified, an assessment that the hazard and associated risks are soinsignificant, that they do not require prevention, control, or monitoring. (The available ShellRisk Assessments have been developed to fulfil these requirements for the categories of siteto which they apply see Section 5.) The output of the Tier 1 assessment should be astatement with justification, of the risks identified and a specification of appropriate riskmanagement provisions. The statement should include details of any significant uncertaintyor disagreement over the required standards or their justification, and proposals for resolvingthese.

Where a Tier 1 analysis provides insufficient understanding of the risks, a Tier 2 or Tier 3assessment should be carried out, as appropriate (see Section 6). The output should be adescription of the identified risks according to significance, identification of those risksrequiring control or reduction and details of the proposed risk management measures. Itshould provide sufficient understanding of the contributing factors to establish the variousoptions for managing the risk (see Figure 1 and section 2.3).

3.7 Licence conditions, risk assessments, risk management systems and working plans

In licence conditions prepared using the Library or Shells, Condition 1.1 sets limits for thewaste management operations that may be carried out on the site under the licence, andcondition 1.2 sets limits on the wastes that may be received on the site and subjected to thoseoperations, in terms of the types of waste and their environmentally hazardous properties.

The specification of the operations and of the waste types and hazards, taken together,characterise the source of the risks to the environment that will be posed by the site. Theytherefore determine the measures that will be necessary to prevent and manage those risks tothe environment, and the scope of the other licence conditions that will be necessary. Thoseother licence conditions will define the risk management systems that must be provided bythe operator, and will set the performance standards that those systems must meet. The



working plan will therefore need to describe the site operations and risk management systemsto a level of detail that shows, clearly and convincingly, that those requirements andstandards will be met.

The licence conditions and sub-conditions prepared using the Library or Shell templates willfall into two basic types: conditions that set absolute standards which include specifying the means by which they

shall be achieved; and conditions that set a standard but specify the means by which it shall be achieved by

including a reference to specified section(s) of the working plan.

Although the working plan is produced by the operator and is their document, those sectionsspecifically referenced in the licence conditions become an operational and enforceable partof any licence issued. The Agency therefore approves those referenced sections of theworking plan prior to the issue of a licence. The licence conditions will also include:

a general requirement that any proposed changes to those referenced sections of theworking plan must be supported by an assessment of their effect on the environmentalrisks of the site, and notified to the Agency before they are implemented; and

a specific requirement for those sections of the working plan which are identified asdescribing environmentally significant risk management provisions, that the changes areapproved by the Agency before they are implemented.

The environmental risk assessment of the site therefore becomes a living document which iskept under review throughout the life of the site.



4 DEVELOPING THE CONCEPTUAL MODEL

Fundamental to environmental risk assessment is the problem definition (or formulation)stage, which enables a clear picture to be established of the site and its environment, basedupon the nature of the site (including the wastes to be received and handled, and the wastemanagement operations to be carried out) and its environmental situation (including thepotentially vulnerable environmental receptors in the vicinity of the site).

Irrespective of the tier of the assessment being undertaken, the first key steps are to identifythe hazards and consequences that might arise. The hazards for a waste management facilitycan be readily identified from knowledge of the types of wastes to be accepted and theprocesses they will undergo at the facility, be they treatment, storage, disposal, etc.

Then, it is critical to have an understanding of the circumstances of exposure what or whois exposed to which hazards and by what means; i.e. the receptors and the pathways. Theassessor should draw a picture of the site and its environment, which will enable them toidentify and analyse:

the sources of environmental hazard that the site will present during its operations; the potential events and pathways by which the environment will be exposed to those

hazards; the potential receptors or targets who will be impacted by those hazards; and the potential consequences to or effects upon those receptors or targets.

This will usually be achieved by literally sketching out and then refining drawings andplan(s) of the site, which show the proposed, or existing, waste management facility and itsenvironment. This will enable the assessor to develop a valid and reliable model (aconceptual model) of the site, its hazards and its environment. The model may be basedsolely on plans and/or diagrams, but will more usually include a table or spreadsheet whichidentifies the sources of environmental hazards that the site will present, the potentialpathways and the potential receptors, and helps the assessor to screen and assess theenvironmental risks with confidence. (DETR, Environment Agency and Institute forEnvironment & Health, 2000.)

The plans, diagrams and models will be progressively developed through the Tier 1 screeningassessment, and may be further refined, by data collection, for example, to support detailedquantified assessments at Tier 2 and Tier 3. The final, site-specific environmental riskassessment is based on a combined pictorial and analytical model of the site that reliablyrepresents the site and its environment to the required levels of detail and accuracy. Theplans and models will typically develop through the following stages:

Pre-licensing application discussions to develop the conceptual model for a site may bebased initially upon outline plans and designs. These may start out as outline sketchesand develop from there. They will usually be developed in support of the planningapplication.



Conceptual pictures and models are a useful starting point for scoping the site and itsenvironment. Figure 6 shows examples of simple conceptual models for landfillcatchments (taken from Environment Agency, 2000k in preparation).

By the time the licence application is being submitted for consideration, the conceptualmodel will need to be based upon a detailed scale plan of the site and its surroundings.

Site-specific scale drawings and plans are usually essential for a Tier 1 screeningassessment to be carried out, in order to ensure that the model used is relevant, valid andreliable for the site in question. These will usually be available in the form of the outlineor detailed plans and designs that the applicant has produced for their planningapplication. The applicant may also have developed an environmental risk assessmentmodel to support an EIA submitted with the planning application.

Figure 7 shows an example of the sort of site-specific plan (in this case, of a combinedlandfill and transfer station) that could be used. Examples of environmental receptors thatmay be relevant to the site-specific risk assessment are indicated on the conceptual planby call-out boxes. These would be taken into consideration in the Tier 1 risk screeningassessment (see Chapter 5). The risk management measures which are assessed as beingnecessary to prevent harm to these receptors would then be incorporated in the detaileddesign and plans for the site, as the conceptual model is developed.

The plans and model are then refined as the risk assessor (Agency and/or applicant)reviews the risk assessment against the actual site and its environment. This developmentprogresses as necessary through the various tiers of assessment, until understandingdevelops to the level appropriate to the risk management decision.

The plans and model for a site must be developed on the basis of the actual site and itsenvironment, and while desk-based studies and reviews may provide some of the basis,site-based inspections and reviews are essential. While development of the site-specificmodel and assessment should be led by the applicant/operator, it should be based uponactive discussion with the Agency officer dealing with the application, who should alsoconsult the Agency officer who is or will be responsible for inspecting the site against itslicence conditions.

Further guidance on developing conceptual models (with specific application to modellingcontaminant transport processes in the subsurface) is provided in Environment Agency,2000h.



Figure 6: Examples of conceptual models - simplified landfill catchment drawings.


Sewerconnection

Perimeter fence

Transferstation

Figure 7: Example of a conceptual plan of a combined landfill and transfer station, indicating examples of potentialenvironmental receptors

Perimeter fence

Claybund

Exemptarea

Screener

Concretepad

Gate

Wheelspinner

Mainroad

Wheel wash

Weighbridges& office

Carpark

Site office &laboratory Quarantine

storagelagoon

Leachatelagoon

m0 10 20 30 40 50

Phase 2 landfill compositelined

Phase 1 landfill compositelined

Farm house & barns

Bays

People & Property; e.g.inhabitants, workers, school,hospital, factory, offices.

People & Property;e.g. inhabitants,houses.

People & Property;e.g. inhabitants,workers, buildings,livestock.

Ecosystems;e.g. designatedHabitat, SSSI.

Surface water

River / stream

Groundwaterbelow & invicinity of site

1

2

3



5 TIER 1: SCREENING OF ENVIRONMENTAL RISKS

5.1 Introduction

This chapter explains what Tier 1 screening assessment is, based on the source-pathway-receptor approach, and describes its use in the form of the Shell Risk Assessments whichform the basis of the Shell Licensing Kits. Examples and relevant tables are given,supported by Appendix 1, 2, 3 and 4. It discusses the use of scoring in the rating andprioritisation of risks and risk management systems. An example is given in Appendix 5.

5.2 Screening of environmental risks for waste management sites

A typical screening assessment of the environmental risks of a site consists of a qualitativeassessment which identifies: what risks there are to the environment from the proposed site operations what standards of environmental protection are required to manage those risks which, if any, of the identified environmental risks require a more detailed technical risk

assessment:a) to resolve uncertainty over the identification or significance of the risk; and/orb) to determine the necessary standards of environmental protection.

Screening assessments should be based upon a conceptual model which analyses the source-pathway-receptor links for the site, and, as described in Section 4, this model usually takesthe form of a table, matrix or spreadsheet. This identifies the sources of the hazards, thepathways through which those hazards may be transmitted into the environment and bywhich they might reach the things we wish to protect (i.e. the environmental receptors).

Situations in which either a source, a pathway or a receptor will not be present, or where thelikelihood of them becoming connected is justifiably negligible, can be screened out. Wherethere is significant uncertainty concerning the presence or connection of a source, pathwayor receptor, then the situation should not be screened out without further investigation ormore detailed assessment.

In waste management licensing, the identification of a plausible or likely link between thesource of an environmental hazard via a potential pathway to a potential receptor isconsidered to be sufficient to warrant risk management measures being stipulated in thelicence conditions, unless the site-specific risk assessment demonstrates that, for the site inquestion, the environmental risk is so low that such measures are unnecessary.

The scope, type and standard of risk management measures that will be required will dependupon the environmental hazard and upon the identified environmental risks. In wastemanagement licensing, many sites will fall within typical categories (such as various types oftransfer stations) where the activities they carry out and the environmental risks they give riseto are known and understood well enough that the risk management provisions they willtypically require can be identified and specified as default risk management standards.These are standards that will normally be required in default of any more detailed site-specific assessments indicating that either a lesser or a higher standard of risk management



provision is required for that particular site. This is the level of assessment that is providedthrough the Shell Risk Assessment approach.

As uncertainty increases however, and the likelihood of severe consequences become lessclear, a more detailed assessment of the source-pathway-receptor is necessary to understandthe nature of the risks and how to avoid, or manage them. The Shell Risk Assessmentapproach can be used to identify where these more detailed assessments are needed.

5.3 Shell Risk Assessments

Shell Risk Assessments are Tier 1 screening assessments. These are for use in definedcircumstances by the applicant/operator and by the Agency in producing a site-specific riskassessment in support of the licence application or a licence modification.

Each Shell Risk Assessment is based on: a typical site for the category of site in question(for example, A11: Household, Commercial and Industrial waste transfer station), which isdefined in terms of: the waste categories that will typically be permitted on that category of site, including

references to the relevant Level 1 waste categories listed in the UK Waste ClassificationScheme (UKCWS); and

the waste management operations that will typically be permitted on that category of site,which will fall within the general classifications of storage (or keeping), treatment(including physical, chemical, biological and combinations thereof) and disposal(including treatment operations which are an inherent part of the disposal), and which willalso include the handling operations which are inherently associated with thoseoperations.

(The waste operations will be classified within the licence conditions with reference, whereapplicable, to the Waste disposal and Waste recovery classification list (the D and Rlist) which is given in the Waste Management Licensing Regulations 1994, Schedule 4, PartsIII and IV.)

Typical sites can be regarded as those which provide a good fit with the shell riskassessment, the shell licence conditions and working plan. A good fit is defined as whereneither the applicants risk assessment nor the Agencys evaluation of that risk assessment,justify either:a) detailed quantitative risk assessments to be carried out; orb) significant variations in the risk management provisions from those described in the

working plan or from the default standards; orc) significant variations from the default standards specified in the shell licence

conditions.

Appendix 2 provides an example from the Shell Licensing Kits used by the Agency.

Hazards and risks can be ranked or scored using qualitative indicators, such as high,medium, or low, and this can be useful in helping to identify the type and degree of riskmanagement measures that are appropriate in a particular case. Box 2 explains how thisworks in the Shell Risk Assessment tools.


National Centre for Risk

a practical guide to environmental risk assessment for ...infohouse.p2ric.org/ref/16/15252.pdf · a...

Documents