Further description:- United Kingdom  Risk assessment 

Glossary Entry:- United Kingdom  Risk assessment
Risk assessment provides an objective, technical evaluation of the likelihood of unacceptable 
impacts to human health and the environment. The purpose is to assess the need for protective measures,
since a specific risk assessment is a precondition for any such protective measures.
Overview
Official guidance in the UK, such as 'CLR11 Model procedures for the management of land contamination' 
published by Defra and the Environment Agency, makes if clear that risk assessment is the essential
starting point in managing risks posed by land contamination. Risk assessment provides a structed mechanism for deciding if contamination poses unacceptable
risks to people, their property or the environment and making judgements about how best to manage
these risks. This underpins the “suitable for use” approach adopted in the UK for the management of
contaminated land. This applies equally to land contamination encountered during redevelopment
(eg planning and building control systems) or the durties of local authorities under Part IIA of the
Environmental Protection Act 1990.
1. General Approach
 
  
High-level UK policy guidance on environmental risk assessment states that “the interaction 
between human activity and the environment is complicated and difficult to quantify, and it is not
easy to judge where the balance should lie between environmental protection and economic and technological
progress. Environmental risk assessment is a key element in the appraisal of these complex problems,
and for formulating and communicating the issues so that transparent and equitable policy, regulatory
or other decisions can be taken” (DETR, 2000,'Guidelines for Environmental Risk Assessment and
Management') Within this context, the UK has adopted a risk-based approach to the identification, assessment
and management of contaminated land, which embraces the source-pathway-receptor concept. This
approach is considered to protect human health and the wider environment, avoid unforeseen impacts
on the construction processes and ensure that resources are applied in a manner proportionate to
the risks identified. At the core of this approach is a risk assessment that identifies and determines the significance
of the risks posed to possible receptors, particularly those specified under Part IIA of the Environmental
Protection Act (1990) namely:
  • Human beings
  • Controlled waters (surface and ground water)
  • Protected ecological systems
  • Property:
    • Crops, including timber
    • Produce grown domestically, or on allotments, for consumption
    • Livestock
    • Other owned or domesticated animals
    • Wild animals which are the subject of shooting or fishing rights
    • Buildings
Risk assessment of contaminated land can be required for a number of different reasons, for example,
to demonstrate “suitability for use” as part of a planning application, to allow a local authority
to determine the site as “Contaminated Land” under Part IIA of the Environmental Protection Act (1990)
or as part of the due diligence process during the sale of land etc. The ultimate use of the assessment
may have some effect on the format and detail of risk assessment but the basic principles described
below should be applicable in most cases. The Pollutant Linkage Concept Risk assessment in the UK relies on investigating the likely presence and significance of a pollutant
linkage; for a risk to exist there must be a source of contamination, a receptor that may be impacted
and a pathway connecting them. Such a source-pathway-receptor relationship is termed a pollutant
linkage
. If either the source, pathway or receptor is absent, no linkage exists and thus no likelihood
of risk. There may be one or more linkages at any given site and any given source may pose a risk to one or more
receptors by one or more pathways. Equally, a receptor may be at risk from one or more sources. The potential
pollutant linkages at a site are usually summaries within a site conceptual model. Having established what pollutant linkages are present or are likely to be present at the site in
question, further risk assessment is required to establish whether these pollutant linkages are
significant. In the UK a tiered approach to such risk assessments is usually adopted. This generally
involves a qualitative risk assessment, followed, where necessary, by either a generic quantitative
risk assessment
or a detailed quantitative risk assessment. Conceptual Model The conceptual model is a key component underpining the entire risk assessment process and is also
a requirement of BS10175, one of the British codes of practice covering the investigation of potentially-contaminated
sites. It is a visual and schematic representation summarising the source, pathway and receptor
components of pollutant linkages at the site in question and the uncertainties in understanding
these components. The initial site conceptual model is formulated during the qualitative risk assessment but is
continually modified and improved as the risk assessment process proceeds. As more detailed information
about the site becomes available (the results of site investigation activities, for example), the
uncertainties in the conceptual model is reduced and it may be possible to reject some potential pollutant
linkages on the grounds of insignificance. Thus at any given stage in the risk assessment process
the conceptual model identifies the remaining potential pollutant linkages of concern at the site.
These linkages require either further risk assessment to determine their significance or require
risk management (e.g remediation) actions to be taken to mitigate the risks that are posed. Qualitative Risk Assessment The first stage of any risk assessment is a qualitative consideration of the sources and receptors
and potential linkages between them based on factors such as the likelihood of each element being
present and the magnitude of the potential harm. For example, is exposure to a contaminant likely
to result in death, serious disease or skin irritation? Such qualitative assessments enable potentially significant pollutant linkages to be identified
for more detailed assessment, as well as enabling some linkages to be excluded from further consideration
on the basis of their not being plausible. The greatest potential for the introduction of uncertainty in the risk assessment process is during
the qualitative risk assessment and the development of the initial conceptual model. If the conceptual
model is inadequate, ill-informed or does not adequately reflect the site in question - for example,
a significant pollutant linkage being overlooked -the subsequent stages of the process will be flawed.
Consequently, reliance on generic, rather than site-specific, information about potential contaminants
and pollutant linkages is likely to lead to an over-cautious assessment and will result in large numbers
of linkages requiring quantitative assessment. Thus, during the preparation of the conceptual
model, every effort should be made to obtain site-specific information about the site and its historic
uses, for example, the substances used, disposed of or released during site operations. Quantitative Risk Assessment Quantitative risk assessments are carried out in a sequence of ever-increasing data quality and
ever-decreasing conservatism, focusing in on potentially significant pollutant linkages remaining
within the conceptual model. This sequence may be described as a series of tiers:
  • Comparison against conservative generic assessment criteria – Generic quantitative risk
    assessment
  • Comparison against less conservative assessment criteria derived specifically for that
    site - Detailed quantitative risk assessment A number of different ways of sub-dividing these tiers have been proposed in various documents,
    but the details are not as important as the principle of a step-wise approach. Generic quantitative risk assessment (GQRA) Up until the publication of recent guidance on quantitative risk assessment in the UK (), most risk
    assessment of contaminated land had been restricted to GQRA. This involves the comparison of site
    concentrations of contaminants in soil, water or gas/vapour samples with generic assessment criteria,
    which are assumed to represent “safe limits”. Historically, GQRA was typically restricted to comparing
    the concentration of contaminats in soils with values taken from sources such as ICRCL Guidance Note
    59/83 or the target/intervention values derived by the Dutch government. However, the implementation of Part IIA in the UK has driven considerable changes in acceptable
    practice and available guidance. In particular, it has resulted in the withdrawal of ICRCL Guidance
    Note 59/83 for the assessment of risks to human health and the applicability of the “Dutch values”
    under Part IIA is also in question. To replace these generic assessment criteria, Defra and the Environment
    Agency is in the process of deriving Soil Guideline Values (SGVs), which are intended to be conservative
    values representing levels of contaminant in UK soils below which it can be assumed that no risk to
    human health exists. Initially, SGVs have been produced for a limited number of metallic contaminants
    but it is anticipated that values will be derived for a much wide range of contaminants in the future.
    It should also be noted that it may be necessary to consider risks to other receptors, such as surface
    and ground waters, ecosystems and buildings/building materials. Generic assessment criteria
    designed to protect these receptors and guidance on their use have also been produced by a variety
    of sources. Detailed quantitative risk assessment (DQRA) Where the comparison of site concentrations with generic assessment criteria indicate that a
    pollutant linkage may still pose an unacceptable risk, or where no generic criteria exists, two courses
    of action are possible:
  • Implement risk management measures to ensure that the risk is adequately mitigated
  • Undertake further detailed quantitative risk assessment to further determine if the risk
    is significant Detailed quantitative risk assessment involves the gathering of additional site data usually
    relating to soil and groundwater processes that effect contaminant fate and transport. This data
    can be used to reduce the level of conservatism in the generic assessment criteria used in GQRA. Typically
    this involves parameters such as soil organic fraction, soil bulk density, soil porosity and hydraulic
    conductivity, depending on the type of assessment being performed. This allows site-specific assessment
    criteria to be derived that more accurately represent the levels of contamination that pose a risk
    at that particular site. These can be compared with site concentrations of contaminants to identify
    if they continue to represent a significant risk. A risk assessment tool or model is usually employed to derive site-specific assessment criteria.
    These use mathematical algorithms to predict the likely exposure of the receptor based on the data
    and assumptions input into the model. It is important, in a UK context, to ensure that the model employed
    to derive site-specific assessment criteria is compliant with UK policy. Some of this policy is laid
    down in the guidance contained in CLR 7, 8, 9 and 10 (Defra & EA, 2002 a-d). One such model is the Contaminated
    Land Assessment Model, which has been developed on behalf of Defra and the Environment Agency in order
    to derive the UK Soil Guideline Values. Another simpler model has been developed by the Scotland and
    Northern Ireland Forum for Environmental Research (SNIFFER), although a number of other models
    exist that can be modified in order to comply with UK policy. Additional rounds of DQRA, generating even more site-representative assessment criteria, can
    subsequently be considered using site data representing, for example, contaminant bio-accessibility
    or soil/plant concentration ratios. However, the benefit of such assessments must be weighed against
    the likely cost of fulfilling the additional data requirements. The Need for Risk Management The tiered approach to risk assessment adopted in the UK, allows the pollutant linkages which pose
    potentially unacceptable risks to be identified at each stage, with the number of such linkages reducing
    as the level of uncertainty is reduced during the process. The remaining linkages at the conclusion
    of the risk assessment process potentially pose unacceptable risks. In these cases risk management
    options, usually remediation, are required to ensure that the identified receptors are adequately
    protected. However, the staged process also allows for significant flexibility. For example, quantitative
    risk assessment may be bypassed if a given linkage obviously poses an unacceptable risk, consequently
    avoiding wasted effort. Equally, immediate action can be taken if the initial assessment indicates
    that contamination may already be impacting a receptor.
  •  
    2. Policy and Regulation
    2.1 Policy
     
      
    UK policy and guidance on the risk assessment of contaminated land has developed swiftly since 
    2000, driven by the implementation of new legislation designed to address contaminated land, such
    as Part IIA and changes to the planning and building control systems. This developing policy has been
    published by various authoritative bodies in a number of guidance or decision support documents.
    Much, although not all, of this guidance is contained within the Contaminated Land Research (CLR)
    series of documents jointly published by Defra and the Environment Agencey. The basic UK approach
    and terminology used in all risk assessment of contaminated land in the UK is outlined in CLR11 'Model
    procedures for the management of land contamination' (Defra & EA, 2004). This is supplemented by
    other documents in the CLR series, such as CLR7 'Assessment of risks to human health from land contamination:
    An overview of the development of Soil Guideline Values and related research' (Defra & EA, 2002).
     
    2.2 Regulation
      
      
    Part IIA of the Evironmenatal Protection Act (1990) and the associated regulations and guidance 
    for England, Scotland and Wales, set out the procedures to be followed by local authorities to determine
    land as 'contaminated land' and enforce its remediation (if neccesary). These procedures are based
    on risk assessment. In general, the requirement for risk assessments to be carried out before the development of brownfield
    sites is regulated by the local authority (often in conjunction with the Environment Agency). The construction (or significant modification) of buildings within the UK is subject to the approval
    of the local authority under the Town and Country Planning Act 1990 or Town and Country Planning Act
    (Scotland) 1997 and associated regulations and guidance. Contamination is a material consideration
    under the planning system. Where contamination may be present, a risk assessment may need to be prepared
    and agreed by the local authority before planning permission is granted. This is explained in more
    detail:
  • for England, in PPS23 - 'Planning Policy Statement 23: Planning and Pollution Control' (ODPM,
    2004)
  • for Wales, in Chapter 13 of 'planning Policy Wales (Welsh assembly, 2002)
  • for Scotland, in PAN33 - 'Development of contamianted land' (Scottish Executive, 2000)
  • for Northern Ireland, updated guidance is not yet available. Buildiing is also subject to building control inspection under the The Building Act 1984 or The
    Buidling (Scotland) Act 2003 and associated regulations and guidance. Adequate risk management
    will be needed based on a suitable risk assessment where containants may be present. The requirements
    are explained in more detail:
  • for England and Wales, in Approved Document C 'Site preparation and resistance to contaminants
    and moisture' (ODPM, 2004)
  • for Scotland, in Technical Standards Part G 'Preparation of sites, resistance to moisture
    and resistance to condensation' - updated guidance is not yet available
  • for Northern Ireland, in Technical Booklet C 'Preparation of site and resistance to moisture
    guidance is not yet available - updated guidance is not yet available.
  •  
    3. Funding
    Site Project Funding
    No information on project funding is currently available on EUGRIS 
     
    R&D funding
    Soil Protection
    Research Type: Applied

    Topics: Brownfields Contaminated land, Contaminated land overview Contaminated land, Remediation options, Remediation options overview Groundwater protection, Groundwater protection overview Soil, Soil Overview

    Submitted by: Maike Hauschild  Who does what?

    Full Details |


    Soil Biodiversity Programme
    Research Type: Basic

    Topics: Brownfields Contaminated land, Contaminated land overview Contaminated land, funding Soil, Soil Overview

    Submitted by: Maike Hauschild  Who does what?

    Full Details |


    URGENT (Urban Regeneration and the Environment)
    Research Type: Basic

    Topics: Brownfields Contaminated land, Contaminated land overview Contaminated land, funding Groundwater protection, Groundwater protection overview Soil, Soil Overview

    Submitted by: Maike Hauschild  Who does what?

    Full Details |


    'Infrastructure and Environment' programme and 'Engineering' programme
    Research Type: Basic

    Topics: Engineering, Infrastructure and Environment, Brownfields, Contaminated land, Groundwater protection, Funding, Brownfields Contaminated land, Contaminated land overview Contaminated land, funding Groundwater protection, Groundwater protection overview

    Submitted by: Maike Hauschild  Who does what?

    Full Details |


    Bioremediation LINK Programme
    Research Type: Applied, Basic

    Topics: (1) To understand and exploit natural attenuation in groundwater and soil (demonstration, modelling, prediction, definition of operating window). (2) To improve engineered in-situ bioremediation, interfacing microbiology with engineering and hydrogeology; dealing with heterogeneity, improved process control and optimisation. (3) To translate the results of laboratory studies into the field (scale-up). (4) To position bioremediation within a risk management framework - bioavailability, risk-based end points and residue behaviour. (5) To develop the ability to monitor in-situ microbial processes. (6) To understand the constraints on in-situ microbial processes. (7) To integrate bioremediation with other technologies. (8) To quantify human health impacts of bioremediation and develop surrogate testing. (9) To address socio-economic issues- perception of bioremediation technologies and decision-support mechanisms.

    Submitted by: Professor Paul Bardos  Who does what?

    Full Details |


    Land Contamination
    Research Type: Applied

    Topics: site assessment for land contamination, decision support tools for risk management, remediation of contaminated soils, sediments, and groundwater, Brownfields Contaminated land, Contaminated land overview Contaminated land, funding Groundwater protection, Groundwater protection overview

    Submitted by: Maike Hauschild  Who does what?

    Full Details |


    Defra Web Page on: Contaminated Land - funding
    Research Type: Demonstration

    Topics: There are several measures which support the clean up of contaminated land, and these are described on this web page

    Submitted by: Professor Paul Bardos  Who does what?

    Full Details |



    Market Information
    No market information is currently available on EUGRIS 
     
    4: Management tools / decision support and guidance

    No further information available

    5. Authors
    
    
     
        
    6. Acknowledgements
    Based on the article Bardos, Nathanail & Nathanail (2003) “Risk assessment – have you got a real problem?” 
    Waste Management, November 2003, p44-46