SIST EN ISO 21365:2020

SLOVENSKI STANDARD
oSIST prEN ISO 21365:2020
01-februar-2020
Kakovost tal - Modeli za domnevno onesnažena območja (ISO 21365:2019)
Soil quality - Conceptual site models for potentially contaminated sites (ISO 21365:2019)
Qualité du sol - Schémas conceptuels de sites pour les sites potentiellement pollués
(ISO 21365:2019)
Ta slovenski standard je istoveten z: prEN ISO 21365
ICS:
13.080.01 Kakovost tal in pedologija na Soil quality and pedology in
splošno general
oSIST prEN ISO 21365:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 21365:2020
INTERNATIONAL ISO
STANDARD 21365
First edition
2019-10
Soil quality — Conceptual site models
for potentially contaminated sites
Qualité du sol — Schémas conceptuels de sites pour les sites
potentiellement pollués
Reference number
ISO 21365:2019(E)
©
ISO 2019

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ISO 21365:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Email: copyright@iso.org
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Published in Switzerland
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ISO 21365:2019(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Basics . 3
4.1 Structure of this document . 3
4.2 Principles . 4
4.3 Scope of a conceptual site model . 5
4.4 Representing and communicating a conceptual site model . 5
5 Development of a conceptual site model . 6
5.1 Step wise procedure . 6
5.2 Step 1: Defining overall objectives and the boundaries (both spatial and temporal) . 8
5.3 Step 2: Identifying the known and potential contaminant(s) and characterizing the
source . 8
5.4 Step 3: Identifying and characterizing each known and potential contaminated medium . 9
5.5 Step 4: Identifying potential migration pathways .10
5.6 Step 5: Identifying potential receptors, exposure pathways and points of exposure .13
5.7 Step 6: Identifying possible foreseeable events .15
6 Conceptual site model development during site investigation .15
6.1 General .15
6.2 Preliminary investigation .16
6.3 Exploratory investigation .17
6.4 Detailed investigation .17
6.5 Supplementary Investigation .17
7 Conceptual site model for remediation and mitigation measures .18
8 Conceptual site model for construction works .18
9 Data collection and Quality Assurance .19
Annex A (informative) Expressions and illustrations of conceptual site models for
potentially contaminated sites .20
Annex B (informative) Scope of phases of investigation (based on ISO 18400-203) .33
Annex C (informative) Investigations phases and links with conceptual site model (adapted
from ISO 18400-202 and 18400-203) .35
Annex D (informative) Review during and after Remediation and Construction works .37
Bibliography .39
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Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document can be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee
SC 7, Impact assessment.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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Introduction
This document provides a definition of the conceptual site model (CSM) for contaminated sites
consistent with other ISO standards related to contaminated land. It refers to ISO accepted terminology
and generally accepted understanding of a CSM. Links with the ISO 18400 series of standards (Soil
quality — Sampling) are made. It is applicable to the management of potentially contaminated sites,
sites that are known to be contaminated, and also to land with naturally elevated concentrations of
potentially harmful substances.
It provides general guidance on the application of CSMs, how they are developed and how they can
evolve, with respect to all media, for example, air, surface water, sediments, soil, groundwater, soil gas,
biota, subsoil, including buildings and other artefacts.
The CSM is a synthesis of all relevant information about a potentially contaminated site with
interpretation as necessary and recognition of uncertainties. The description relies on the concept, of
“source-migration pathway-receptor linkages” (sometimes termed « contaminant linkages ») that are,
or might be, present.
The investigation of land potentially affected by contamination is usually performed using observations
and measurements made on-site as well as by taking samples for laboratory analysis and testing. Soil
and groundwater characteristics include a wide span of features, such as chemical and mineralogical
composition, soil texture, the concentrations, amounts and distribution of contaminants and soil
components. For practical and economic reasons, these investigations cannot cover the total volume of
interest, and the on-site measurements and especially the sampling have to be limited to certain points
or small areas/volumes.
Spatially limited investigations will give the best possible information if they are be planned thoroughly.
The questions: “what are we looking for, and what can we expect?” are essential for developing an
investigation programme that is efficient and fit for purpose. The best way to start the planning of the
investigation is to formulate a CSM, based on a thorough preliminary investigation (desk study and site
reconnaissance in accordance with ISO 18400-202) prior to any intrusive investigation.
Therefore, a CSM is a synthesis of information about the site together with some interpretation,
assumptions, and hypotheses. By testing the assumptions and hypotheses, intrusive investigations
can concentrate on the essential questions and data gaps, and can be planned and carried out more
efficiently. Depending on the results of the intrusive investigation, the CSM can be developed further.
It can become more detailed, more reliable, and often also modified or corrected, and step by step can
lose its conceptual character, although remaining a model.
In the context of potentially contaminated land, a CSM is a tool that can be developed for the planning of
an investigation, for undertaking a risk assessment, and for planning remediation and aftercare of a site.
It can also be used for construction or other engineering works that are planned for after remediation.
A CSM can be used when conducting environmental audits and “due diligence” exercises. The degree of
detail needed for the CSM can depend on the objectives of any of these tasks, and the nature, current
use and possible development of the site.
When preparing a CSM the terms that are being used should be carefully defined because terms might
not be understood to have the same meaning by people with different backgrounds and experience. In
addition, CSMs are intended to be of use to those without a technical background.
NOTE This document follows the established convention for documents published by ISO Technical
Committee 190 (TC 190) in distinguishing between “contaminant” (“substance or agent present in an
environmental medium as a result of human activity – see 3.2 in this document) and pollutant (“substance
or agent present in the soil (or groundwater) which, due to its properties, amount or concentration, causes
adverse impacts on soil functions” - see ISO 11074:2015, 3.4.18). Hence, “contamination” and “pollution” are not
considered to be the same thing. However, it is recognised that this distinction is not always made at “official”
level in all jurisdictions. Even in those jurisdictions where it is recognised, it might be for some purposes but not
others and the definitions of “contamination” and “pollution” used in legislation and regulations for different
purposes can differ. In addition, the use of the terms is not necessarily consistent between and even within
guidance documents produced by government and professional bodies.
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INTERNATIONAL STANDARD ISO 21365:2019(E)
Soil quality — Conceptual site models for potentially
contaminated sites
1 Scope
This document provides guidance on developing and using conceptual site models (CSMs) through
the various phases of investigation, remediation (if required), and any subsequent construction or
engineering works.
It describes what CSMs are, what they are used for and what their constituents are. It stresses the need
for an iterative and dynamic approach to CSM development.
This document is intended to be used by all those involved in developing CSMs and by those who rely
on using them such as regulators, landowners, developers, and the public (and other relevant parties).
Ideally, this includes representatives from all phases of the investigative and remedial processes, for
example, preliminary assessment, detailed investigation, baseline human health and environmental
risk assessments, and feasibility study, and, any subsequent construction or engineering work.
NOTE 1 This document is applicable whenever the presence of “potentially harmful” or “hazardous”
substances are present irrespective of whether they are naturally occurring or present due to human activity
(i.e. are “contaminants”).
NOTE 2 Although most of the principles described for developing CSMs in this document can apply to other
domains, such as groundwater resources management, the present document is specifically written for the
management of potentially contaminated sites or known contaminated sites.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 11074, Soil quality — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11074 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
anthropogenic ground
deposits which have accumulated through human activity
1)
[SOURCE: ISO 11074:2015/DAmd 1:2019 ]
1) Under preparation. Stage at the time of publication: ISO 11074:2015/DAmd 1:2019.
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3.2
conceptual site model
synthesis of all information about a potentially contaminated site relevant to the task in hand with
interpretation as necessary and recognition of uncertainties
3.3
contaminant
substance or agent present in an environmental medium (3.4) as a result of human activity
Note 1 to entry: There is no assumption in this definition that harm results from the presence of the contaminant.
Note 2 to entry: ISO 11074:2015, 3.4.6 defines “contaminant” as “substance or agent present in soil as a result of
human activity”.
3.4
environmental medium
soil, underlying material, sediments, surface water, groundwater, soil gas, and air that can contain
contaminants (3.2)
3.5
exposure pathway
path, route or other means, a contaminant (3.3) or hazardous substances from a particular source takes
to a receptor (3.7)
Note 1 to entry: Each exposure pathway links a source to a receptor.
[SOURCE: ISO 11074:2015, 5.2.12 modified]
3.6
fill
anthropogenic ground in which the material has been selected, placed and compacted in accordance
with an engineering specification
[SOURCE: ISO 11074:2015/DAmd 1:2019]
3.7
made ground
anthropogenic ground comprising material placed without engineering control and/or manufactured
by man in some way, such as through crushing or washing, or arising from an industrial process
[SOURCE: ISO 11074:2015/DAmd 1:2019]
3.8
migration pathway
means by which contaminants (3.3) or hazardous substances from a particular source of contamination
can spread or distribute
Note 1 to entry: A migration pathway does not necessarily link to a receptor.
3.9
pollutant
substance or agent present in an environmental medium (3.3), which, due to its properties, amount or
concentration, causes adverse impacts on an environmental medium
Note 1 to entry: ISO 11074:2015, 3.4.18 defines “pollutant” as “substance or agent present in the soil (or
groundwater) which, due to its properties, amount or concentration, causes adverse impacts on soil functions”
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3.10
receptor
defined entity that is vulnerable to the adverse effect(s) of a hazardous substance or agent
Note 1 to entry: Receptors might include persons (e.g. trespassers, current and intended users, construction
workers), other organisms or complete ecosystems, environmental media or artificial construction.
[SOURCE: ISO 11074:2015, 3.3.29, modified, note added]
3.11
source
place from which a contaminant (3.2) or hazardous agent is released
Note 1 to entry: ISO 11074:2015, 3.3.35 defines “source” as “place from which a substance or agent is released
giving rise to potential exposure to one or more receptor” (3.7).
4 Basics
4.1 Structure of this document
The structure of this document is shown in Figure 1.
Figure 1 — Content of present document and interactions between the descriptive clauses
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4.2 Principles
The conceptual site model (CSM) is a synthesis of all information about a potentially contaminated site
or a site known to be contaminated, relevant to the task in hand with interpretation as necessary and
recognition of uncertainties.
CSMs are important aids for the development of site-specific investigation programmes, the
undertaking of site risk assessments, remediation design, follow up post remediation, and if necessary
for subsequent construction on those sites that have been managed to deal with contamination. It is
developed following a step-by-step approach (see Clause 5). Its preparation requires judgement by the
person(s) preparing and developing the model.
Once, developed, a CSM should comprise all relevant information, including:
— past and present uses (see ISO 18400-202);
— intended future uses, included where known existing configuration and or future buildings/
infrastructure (e.g. basements, crawlspace under the floor of a building);
— the geological, geomorphological, hydrogeological and hydrological settings, soil, sediments, and
air (indoor air and the atmosphere) of the site and surrounding area;
— the properties of the potential contaminants (e.g. volatility solubility, toxicity) and their sources,
including distribution of contamination [e.g. plume of contaminant(s)], potential migration pathways
(natural and anthropogenic features such as sewer lines) and transport mechanisms;
— potential receptors of the contamination;
— possibilities of new exposure pathways and new receptors associated with the construction and
completion of a new development;
— foreseeable events [e.g. potentials for flooding (rivers, sea, groundwater), rising groundwater or
seawater levels, extreme weather conditions, change of use, etc.].
The aim of a CSM can be, as appropriate, to:
— present the characteristics of the site;
— identify uncertainties and data gaps and act as a basis for designing further investigations and
assessments;
— provides a basis for planning remediation and mitigation measures;
— provide a systematic review of where risks might potentially occur by summarizing possible direct
and indirect exposure pathways;
— facilitate as a communication tool, the overall management of potentially contaminated site, e.g. to
help in the decision-making process of experts in designing and planning all required actions;
— enable experts from all disciplines, clients, members of the public and regulators to communicate
effectively with one another about issues concerning a site and facilitate the decision-making
process.
CSM development should start as early in the site investigation process as possible. It should be
an iterative process of refinement in which the uncertainties are recognized and reduced as more
information becomes available (see Clause 6). The CSM can evolve as the results of investigations
become available and remediation strategies are formed. Refinement of the CSM should continue
through any remediation works and protective mitigation measures (see Clause 7). The planned use of
a site following any remediation cannot always be known when the CSM is first developed. The CSM is
likely to require review and possible extension following construction works and additional protective
mitigation measures as these confirm expected site conditions or reveal new information (see Clause 8).
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Eventually, the CSM should take into account all measures whose implementation can determine the final
acceptability of the project, i.e. the total compatibility of site conditions and current or planned uses.
4.3 Scope of a conceptual site model
The complexity of a CSM should be consistent with the complexity of the site and available data and the
purpose for which it is developed.
The formulation of CSM should make it possible to determine the linkages between:
— the potential sources of hazardous substances (see 5.3);
— the potential migration pathways, including the various transport mechanisms in each medium and
their characteristics (see 5.4 and 5.5);
— the existing and/or future receptors that must be protected (see 5.6).
A CSM should:
— be developed for a defined purpose;
— be no more complex and detailed than required by the task in hand;
— identify uncertainties in the available information and in the conclusions.
A CSM should be prepared taking into account:
— the objectives of the investigation, or the purpose of the remediation (if required) and the purpose
of any subsequent construction or engineering works;
— the reason(s) for preparing the CSM, e.g. to aid risk assessment, help communicate with interested
parties, to plan remedial measures, or any subsequent construction or engineering works;
— uncertainties in the available data and other information.
The concerns of environmental risk assessment are different from those of human-health risk
assessment. These differences are usually sufficient to warrant separate descriptions and
representations of the CSM in the human health and environmental risk assessment reports. There can
be elements of the CSM that are common to both representations. However, the risk assessors should
develop these together to ensure consistency.
4.4 Representing and communicating a conceptual site model
The development of a CSM helps integrate technical information from various sources so it can be used
to communicate effectively.
A fully developed CSM can be seen as a mental construct of all the gathered information (see the six
steps in Clause 6). The CSM or one or several aspects of the CSM can be expressed or presented using
one or more of the following approaches/representations:
— a text description of the site and all relevant features and processes;
— one or more maps of the site;
— one or more tabular or matrix description;
— one or more drawings or other diagrammatic illustration;
— a series of hypotheses to which qualitative probabilities can be attached.
For example, a diagram can be used to illustrate important examined questions on a potentially
contaminated site. It can also help to identify and formulate what the risks are, i.e. understanding what
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the sources of contaminants, the migration pathways and receptors are. This allows an understanding
of a site in a simple and schematic way.
Examples of the various representations of CSM are provided in Annex A.
5 Development of a conceptual site model
5.1 Step wise procedure
Six main steps have been identified for the development of a realistic and complete conceptual site
model (CSM) of a potentially contaminated site (see Figure 2). The six steps are:
1) defining the overall objectives and boundaries (both spatial and temporal);
2) identifying the known and potential contaminant(s) and characterizing the source;
3) identifying and characterizing each known and potential contaminated medium;
4) identifying potential migration pathways;
5) identifying receptors, exposure pathways and the points of exposure;
6) identifying possible foreseeable events.
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Figure 2 — Diagram illustrating the 6 steps to develop a conceptual site model (Adapted from
[20]
French National guidance on developing conceptual site model )
The CSM should be reviewed by re-considering the six steps again after each phase of investigation and
regularly throughout the risk assessment process. Changes should be made based on the additional
information that has become available. A note should be made of whether the new information has
decreased or increased the model uncertainties. Further investigation should be considered if the
uncertainties are too great to permit realistic risk assessment(s) to be carried out.
All the relevant information that has been gathered should be taken into consideration, whether it
concerns the sources of contaminants, the migration pathways or the receptors to be protected. The
analysis of conditions for media of concern (e.g. geochemistry, redox conditions) helps determine the
magnitude and extent of migration pathways and help to identify the potential exposure points.
NOTE Depending on the phase of the site investigation, there are different degrees of uncertainty as
to whether contaminants are present and which media are contaminated. To avoid repetition in the text,
“contaminants”, “contaminated medium” or “contaminated site” refer to both potential contaminants, or
potentially contaminated medium or potentially contaminated sites and to confirmed contaminants or confirmed
contaminated medium or confirme
...