Soil quality - Conceptual site models for potentially contaminated sites (ISO 21365:2019)

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.

Bodenbeschaffenheit - Leitfaden zur Erstellung konzeptioneller Standortmodelle für potenziell kontaminierte Standorte (ISO 21365:2019)

Dieses Dokument enthält eine Anleitung zur Entwicklung und Anwendung von konzeptionellen Standort-modellen (CSMs) im Verlauf der verschiedenen Phasen der Untersuchung, Sanierung (falls erforderlich) und aller darauffolgenden Baumaßnahmen oder ingenieurtechnischen Arbeiten.
Es beschreibt, was CSMs sind, wofür sie verwendet werden und aus welchen Komponenten sie bestehen. Es betont die Notwendigkeit für eine iterative und dynamische Vorgehensweise bei der Entwicklung eines CSM.
Dieses Dokument soll durch alle an der Entwicklung von CSMs Beteiligten und durch alle diejenigen, die auf deren Verwendung angewiesen sind, genutzt werden, beispielsweise Regulierungsbehörden, Grundstückseigentümer, Bauunternehmer und die Öffentlichkeit (sowie andere relevante Parteien). Dies schließt idealerweise Vertreter aus allen Phasen der Untersuchungs  und Sanierungsprozesse mit ein, beispielsweise der Erstbewertung, der detaillierten Untersuchung, der grundlegenden Risikobeurteilung für die menschliche Gesundheit und die Umwelt sowie einer Machbarkeitsstudie und aller nachfolgend durchgeführten Baumaßnahmen bzw. ingenieurtechnischen Arbeiten.
ANMERKUNG 1   Dieses Dokument gilt immer dann, wenn ein Vorkommen „potentiell gefährdender“ oder „gefährlicher“ Stoffe vorliegt, und zwar unabhängig davon, ob diese natürlicherweise oder aufgrund einer menschlichen Tätigkeit (d. h. als „Kontaminanten“) vorkommen.
ANMERKUNG 2   Auch wenn die meisten der in diesem Dokument zur Entwicklung von CSMs beschriebenen Grundsätze auf andere Bereiche wie das Management von Grundwasserressourcen anwendbar sein können, wurde das vorliegende Dokument spezifisch für das Management von kontaminationsverdächtigen Flächen oder kontaminierten Flächen verfasst.

Qualité du sol - Schémas conceptuels de sites pour les sites potentiellement pollués (ISO 21365:2019)

Le présent document fournit des recommandations relatives à l'élaboration et l'utilisation de schémas conceptuels de sites (SCS) tout au long des diverses phases d'investigation, de remédiation (si nécessaire) et de tous les chantiers ou travaux de génie civil ultérieurs.
Il décrit ce que sont les SCS, pourquoi ils sont utilisés et quels sont leurs constituants. Il souligne le besoin d'une approche itérative et dynamique pour l'élaboration des SCS.
Le présent document est destiné à être utilisé par toutes les personnes/entités impliquées dans l'élaboration de SCS et par celles qui reposent sur leur utilisation, comme les organismes de réglementation, les propriétaires fonciers, les développeurs et le grand public (et d'autres parties concernées). Idéalement, cela inclut des représentants de toutes les phases des processus d'investigation et de remédiation, par exemple l'évaluation préliminaire, l'investigation détaillée, l'évaluation de référence concernant les risques pour la santé humaine et l'environnement, ainsi que l'étude de faisabilité, et tous les chantiers et travaux de génie civil ultérieurs.
NOTE 1 Le présent document est applicable dès que des substances «potentiellement dangereuses» ou «dangereuses» sont présentes, que leur présence soit naturelle ou due à l'activité humaine (c'est-à-dire qu'il s'agit de «polluants»).
NOTE 2 Bien que la plupart des principes décrits pour l'élaboration des SCS dans ce document puissent s'appliquer à d'autres domaines, comme la gestion des ressources en eaux souterraines, le présent document est spécifiquement rédigé pour la gestion des sites potentiellement pollués ou des sites pollués connus.

Kakovost tal - Konceptualni modeli območij za domnevno onesnažena območja (ISO 21365:2019)

General Information

Status
Published
Public Enquiry End Date
02-Mar-2020
Publication Date
23-Sep-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
12-Aug-2020
Due Date
17-Oct-2020
Completion Date
24-Sep-2020

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SLOVENSKI STANDARD
SIST EN ISO 21365:2020
01-november-2020
Kakovost tal - Konceptualni modeli območij za domnevno onesnažena območja
(ISO 21365:2019)

Soil quality - Conceptual site models for potentially contaminated sites (ISO 21365:2019)

Bodenbeschaffenheit - Leitfaden zur Erstellung konzeptioneller Standortmodelle für

potenziell kontaminierte Standorte (ISO 21365:2019)

Qualité du sol - Schémas conceptuels de sites pour les sites potentiellement pollués

(ISO 21365:2019)
Ta slovenski standard je istoveten z: EN ISO 21365:2020
ICS:
13.080.01 Kakovost tal in pedologija na Soil quality and pedology in
splošno general
SIST EN ISO 21365:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 21365:2020
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SIST EN ISO 21365:2020
EN ISO 21365
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2020
EUROPÄISCHE NORM
ICS 13.080.01
English Version
Soil quality - Conceptual site models for potentially
contaminated sites (ISO 21365:2019)

Qualité du sol - Schémas conceptuels de sites pour les Bodenbeschaffenheit - Leitfaden zur Erstellung

sites potentiellement pollués (ISO 21365:2019) konzeptioneller Standortmodelle für potenziell

kontaminierte Standorte (ISO 21365:2019)
This European Standard was approved by CEN on 31 May 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21365:2020 E

worldwide for CEN national Members.
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SIST EN ISO 21365:2020
EN ISO 21365:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 21365:2020
EN ISO 21365:2020 (E)
European foreword

The text of ISO 21365:2019 has been prepared by Technical Committee ISO/TC 190 "Soil quality” of the

International Organization for Standardization (ISO) and has been taken over as EN ISO 21365:2020 by

Technical Committee CEN/TC 444 “Environmental characterization of solid matrices” the secretariat of

which is held by NEN.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by December 2020, and conflicting national standards

shall be withdrawn at the latest by December 2020.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 21365:2019 has been approved by CEN as EN ISO 21365:2020 without any modification.

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SIST EN ISO 21365:2020
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SIST EN 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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SIST EN ISO 21365:2020
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

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
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SIST EN ISO 21365:2020
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

© ISO 2019 – All rights reserved iii
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SIST EN ISO 21365:2020
ISO 21365:2019(E)
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.
iv © ISO 2019 – All rights reserved
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SIST EN ISO 21365:2020
ISO 21365:2019(E)
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.
© ISO 2019 – All rights reserved v
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SIST EN ISO 21365:2020
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SIST EN ISO 21365:2020
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
[SOURCE: ISO 11074:2015/DAmd 1:2019 ]

1) Under preparation. Stage at the time of publication: ISO 11074:2015/DAmd 1:2019.

© ISO 2019 – All rights reserved 1
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SIST EN ISO 21365:2020
ISO 21365:2019(E)
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”

2 © ISO 2019 – All rights reserved
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SIST EN ISO 21365:2020
ISO 21365:2019(E)
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

© ISO 2019 – All rights reserved 3
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SIST EN ISO 21365:2020
ISO 21365:2019(E)
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).

4 © ISO 2019 – All rights reserved
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SIST EN ISO 21365:2020
ISO 21365:2019(E)

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;

— uncertaint
...

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