oSIST prEN ISO 19204:2026

SLOVENSKI STANDARD
01-april-2026
Kakovost tal - Postopek za oceno ekološkega tveganja onesnaženosti tal za
posamezno lokacijo (pristop TRIAD za kakovost tal) (ISO/DIS 19204:2026)
Soil quality - Procedure for site-specific ecological risk assessment of soil contamination
(soil quality TRIAD approach) (ISO/DIS 19204:2026)
Bodenbeschaffenheit - Vorgehensweise zur standortbezogenen ökologischen
Risikobewertung von Bodenverunreinigungen (TRIAD-Ansatz zur Bewertung der
Bodenbeschaffenheit) (ISO/DIS 19204:2026)
Qualité du sol - Procédure d'évaluation des risques écologiques spécifiques au site de la
contamination des sols (approche TRIADE de la qualité du sol) (ISO/DIS 19204:2026)
Ta slovenski standard je istoveten z: prEN ISO 19204
ICS:
13.080.01 Kakovost tal in pedologija na Soil quality and pedology in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 19204
ISO/TC 190/SC 4
Soil quality — Procedure for site-
Secretariat: AFNOR
specific ecological risk assessment
Voting begins on:
of soil contamination (soil quality
2026-02-02
TRIAD approach)
Voting terminates on:
2026-04-27
Qualité du sol — Procédure d'évaluation des risques écologiques
spécifiques au site de la contamination des sols (approche
TRIADE de la qualité du sol)
ICS: 13.080.01
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FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
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Reference number
ISO/DIS 19204:2026(en)
DRAFT
ISO/DIS 19204:2026(en)
International
Standard
ISO/DIS 19204
ISO/TC 190/SC 4
Soil quality — Procedure for site-
Secretariat: AFNOR
specific ecological risk assessment
Voting begins on:
of soil contamination (soil quality
TRIAD approach)
Voting terminates on:
Qualité du sol — Procédure d'évaluation des risques écologiques
spécifiques au site de la contamination des sols (approche
TRIADE de la qualité du sol)
ICS: 13.080.01
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
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Published in Switzerland Reference number
ISO/DIS 19204:2026(en)
ii
ISO/DIS 19204:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Process overview . . 6
5 Uncertainty and weight of evidence . 7
6 Soil quality TRIAD performance . . 8
6.1 First step: Objective of the investigation (formulating the problem and decision
regarding the need of a site-specific risk assessment) .8
6.1.1 General approach .8
6.1.2 Decision .8
6.1.3 Stakeholders involved in an ecological risk assessment.9
6.1.4 Independent quality control .9
6.2 Second step: Basic considerations .9
6.2.1 General approach .9
6.2.2 Assessment criteria .10
6.3 Third step: Practical performance of the soil quality TRIAD .11
6.3.1 General .11
6.3.2 Soil quality TRIAD TIERS .11
6.3.3 Soil quality TRIAD lines of evidence . 12
6.3.4 Measurement parameters .14
6.4 Fourth step: Assessments at the different TIERS: scaling, weighting and integrating
results .17
6.4.1 General .17
6.4.2 Quantification of results from terrestrial tests .17
6.4.3 Scaling in practise .18
6.4.4 Weighting .18
6.4.5 Integration of results .18
6.5 Fifth step: Decision on how to proceed .19
7 Reporting . 19
Annex A (informative) Bioindicators of effect and accumulation — Additional tools for site-
specific ecological risk assessment .21
Annex B (informative) Toolboxes .22
Annex C (informative) Case studies .29
Bibliography .48

iii
ISO/DIS 19204:2026(en)
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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO [had/had not] received notice of
(a) patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of 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 www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 4, Biological
characterization.
This second edition cancels and replaces the first edition (ISO 19204:2022), which has been technically
revised.
The main changes are as follows:
— Revision/update of toolboxes for the different levels of the TRIAD;
— Quantification (scaling) and aggregation of results at different levels;
— Weighting criteria;
— Selection of the reference zone and use of data from this reference zone;
— Practical examples of the use of TRIAD in an informative annex (in progress).
The feedback from stakeholders and engineering consultants which indicates that, while the different
steps of the method are sufficiently defined, there is still a need for describing it in a more practical way to
facilitate its implementation and reproducibility.
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/DIS 19204:2026(en)
Introduction
This document is set up to ensure the quality of the site-specific ecological risk assessment of soil
contamination. This process was described previously in a report by the Dutch PGBO (Integrated Soil
Research Programme Agency), continued in the current SKB (Foundation for Soil Knowledge Development
[69]
and Transfer). The present document is based on these Dutch reports but has been shortened in order
to increase its general applicability. In addition, parts of the ecological risk assessment framework for
[21][22][23][24][25][26][27]
contaminants in soil prepared by the British Environment Agency were considered
(this tiered framework does use the same three Lines of Evidence (LoE) as the TRIAD but not in parallel
[29][30][68]
but consecutively). Experiences from various other sources, in particular, a summary of a Danish
[36] [35]
study performed as part of the EU FP6 project Liberation, as well as a Danish report, were added.
[10]
The term TRIAD relates to the following three LoE’s: chemistry, ecotoxicology and ecology. Originally,
[38]
it was described as Sediment Quality TRIAD by Long and Chapman. The TRIAD does not particularly
[11]
consist of three lines of evidence (up to five have been proposed ) but in specific situations, two might be
sufficient. Descriptions of the soil quality TRIAD approach in the context of soil contamination are given,
[36] [40] [55] [59] [60] [63] [69] [71] [73]
for example, in References , , , , , , , and. It should be mentioned that the soil quality
[1] [67]
TRIAD is not only used in Central Europe but also in other regions, for example, in Portugal, Italy,
[44] [117][118]
Brazil or South Korea. These publications can be used as case studies for the application of the
soil quality TRIAD.
NOTE Recently, the ecological risk assessment procedures in The Netherlands, Norway, Sweden and the United
[35]
Kingdom were compared. The basic ideas of the TRIAD approach [e.g. a tiered approach and the combination of
information from different disciplines (chemistry, ecotoxicology, and ecology)] have been accepted in these countries.
[21][22][23][24][25][26][27] [40][43][53][58][60][61][63]
However, only in the United Kingdom and The Netherlands have detailed
frameworks been developed. The overall structure of this document combines and modifies both national frameworks
in order to provide guidance independently from the country or region where the site to be assessed is located. The
[36]
terminology of this document does follow the approach described in the EU project Liberation .

v
DRAFT International Standard ISO/DIS 19204:2026(en)
Soil quality — Procedure for site-specific ecological risk
assessment of soil contamination (soil quality TRIAD
approach)
1 Scope
This document describes in a general way the application of the soil quality TRIAD approach for the site-
specific ecological risk assessment of contaminated soils. In detail, it presents in a transparent way three
lines of evidence (chemistry, ecotoxicology and ecology) which together allow an efficient, ecologically
robust but also practical risk assessment of contaminated soils. This procedure can also be applicable to
other stress factors, such as acidification, soil compaction, salinization, loss of soil organic substance, and
erosion. However, so far, no experience has been gained with these other applications. Therefore, this
document focuses on soils contaminated by chemicals.
NOTE 1 This document focuses on ecological risk assessment. Thus, it does not cover human health end points.
In view of the nature of this document, the investigation procedure is described on a general level. It does
not contain details of technical procedures for the actual assessment. However, this document includes
references relating to technical standards (e.g. ISO 15799, ISO 17616) which are useful for the actual
performance of the three lines of evidence.
In ecological risk assessment, the effects of soil contamination on the ecosystem are related to the intended
land use and the requirements that this use sets for properly functioning soil. This document describes the
basic steps relating to a coherent tool for a site-specific risk assessment with opportunities to work out site-
specific details.
This document can also be used for the evaluation of clean-up operations, remediation processes or
management measures (i.e. for the evaluation of the environmental quality after having performed such
actions).
NOTE 2 The application of this document starts when it has already been decided that an ecological risk assessment
at a given site needs to be performed. In other words, the practical performance of the soil quality TRIAD and the
evaluation of the individual test results will be described. Thus, nothing will be said about decisions whether (and if
yes, how) the results of the assessment are included in soil management measures or not.
NOTE 3 The TRIAD approach can be used for different parts of the environment, but this document focuses mostly
on the soil compartment. Comparable documents for other environmental compartments are intended to be prepared
in addition (e.g. the terrestrial aboveground compartment) in order to perform a complete site assessment, based on
the same principles and processes.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/

ISO/DIS 19204:2026(en)
3.1
stakeholder
person or party with an interest in the soil quality (3.21) of a potentially contaminated site
Note 1 to entry: The composition of the stakeholder group depends on the specific local conditions.
3.2
assessment criteria
criteria set up to decide if a site requires further investigation or other action (e.g. remediation)
Note 1 to entry: They can be drawn up by the competent authority (3.3), the stakeholders (3.1) and the investigators
for the interpretation of the results of the soil quality TRIAD study before the investigation is carried out. Two criteria
could be distinguished, namely:
a) threshold that marks the boundary between adequate and inadequate removal of uncertainties in the assessment;
b) threshold that marks the boundary between an effect that is considered acceptable and one that is not considered
acceptable, based on a reference or a limit value.
Note 2 to entry: Assessment criteria are necessary for every collection of ecological conditions (for example, all species
in a generic system, a key species or a protected species).
3.3
competent authority
part of the authorities that is responsible for the implementation of the soil clean-up operation
Note 1 to entry: Depending on the site and the country, the competent authority could be very different. The competent
authority assesses investigation results and takes decisions via decrees about the severity and urgency of the soil
contamination found. The competent authority also assesses the clean-up plans of the clean-up teams on their own
initiative (for example, companies).
3.4
soil management
all the anthropogenic activities that influence the soil system at the site to be assessed
Note 1 to entry: This can include choices in land use (3.5) (e.g. groundwater level management, nature management,
park management, loading with soil-contaminated substances).
3.5
land use
using the ecosystem services (3.8) that the soil provides
3.6
land user
person or group of people who uses the ecosystem services (3.8) of the soil, whereby in the role allocation,
the larger spatial scales are generally represented by organizations, societal parties and authorities
3.7
ecological effect
change to an aspect of the ecosystem caused by anthropogenic stress factors (3.15)
Note 1 to entry: Changes [see also assessment criteria (3.2)] to an ecosystem as a result of the presence of contaminants
are regarded as negative changes regardless of the direction. In this document, the three lines of evidence (LoE) in
accordance with the soil quality TRIAD approach are required for the effect to be determined. In addition, the variation
in space, time and parameters is also important. See also type 1 error (3.17).
3.8
ecosystem service
service that is (directly or indirectly) provided by an ecosystem.
Note 1 to entry: The Ecosystem Service Approach is becoming more and more the theoretical basis for the definition
of protection goals in the context of the risks of chemicals in the environment (e.g. EFSA 2012), including the risk
assessment of contaminated soils (e.g.[2],[41], and[74]).

ISO/DIS 19204:2026(en)
Note 2 to entry: Examples of ecosystem services that the soil provides to people are agricultural products, clean surface
water, groundwater and drinking water, and a healthy environment in which to live. The provision of many of these
services depends in many cases on the activity of diverse organism communities, e.g. degradation of contaminants in
[75]
soil by microbes, meaning that groundwater is kept clean .
Note 3 to entry: Some soil functions (organic substance composition and degradation, natural self-cleaning ability
of the soil and soil structure for a good rooting of vegetation and crops) are counted as ecosystem services in this
context. In detail, four basic soil services are distinguished, namely, soil fertility, resistance to stress and adaptation,
[41]
the soil as a buffer and reactor, and biodiversity. The Millennium Ecosystem Assessment distinguishes at ecosystem
level regulating services (regulation of ecosystem processes), provisioning services (products), cultural services (non-
material benefits) and support services (for the provision of all the other ecosystem services).
3.9
generic assessment
assessment of a site using a general investigation method that is not geared to the properties of the site
3.10
site-specific assessment
assessment of a site using an investigation method that is partially geared to the properties of the site
Note 1 to entry: The assessment consists of a combination of generally applicable and possibly specifically developed
(tailor-made) parts. The interpretation of the results of the investigation is site-specific and can be generalized only to
a limited extent [see also generic assessment (3.9)].
3.11
site-specific model
description of the local ecosystem and of the intended land use (3.5) in terms of ecological conditions for this
use, and of the nature and spread of the contamination.
Note 1 to entry: This model makes it clear which exposure routes are relevant for aspects of the ecosystem that are
needed for the land use (3.5). Suitable parameters can then be selected for the soil quality TRIAD study with optimum
[70]
weight of evidence (3.20) and support .
3.12
uncertainty
degree of doubt about the assumptions or investigation results, to be broken down in the case of the
assessment of the ecological risks of soil contamination into: communications uncertainty, model uncertainty
(epistemic uncertainty), uncertainty because of variation and uncertainty in decision-making
Note 1 to entry: For the different types of uncertainty, see also Clause 5.
3.13
reference
part of a site, of a sample or of a group of literature data that acts as a benchmark for the effect scale (the
baseline, measure or standard)
Note 1 to entry: It is a description of the condition of the soil in quantitative and qualitative terms that can be used as
part of the measure for the soil quality (3.21) to be assessed. The ideal reference is identical to the site (or the sample)
to be assessed, the only difference being that the stress factor (3.15) to be assessed is missing. Chemical, physical and
biological aspects form partial aspects of the reference. For a site-specific application, site-specific details are needed
to obtain an accurate reference. A reference is preferably chosen at the investigation site; measurements are then
preferably taken at the same time as the samples/measurements to be assessed. If no comparable clean reference is
available, the least contaminated sample can also be chosen (for example, in a gradient), on condition that the sample
is regarded as being sufficiently representative to be used as a reference. A reference can also be based on samples of
a comparable site elsewhere or on literature data (= virtual reference).

ISO/DIS 19204:2026(en)
3.14
scaling
process in which measurement or model data are interpreted using a measure intended for this purpose
Note 1 to entry: When applying the soil quality TRIAD (3.16), assessment data are generated to ascertain an effect on
the level of the ecosystem as quantitatively as possible. A practical, standardized scale runs from 0 to 1 or from 0 %
to 100 %. 0 or 0 % represents no effect and 1 or 100 % represent the maximum theoretical effect at a high concentration
of the contaminating substances. Sometimes, only a low level of quantitative scaling is possible, such as on an ordinary
scale or on a 2 or 3 point scale (yes/no or yes/maybe/no). These low quantitative scaling methods can be used in a
weight‑of‑evidence (WOE) (3.20) approach. Examples of scaling are given in, e.g. Reference [40].
3.15
stress factor
outcome of an anthropogenic activity that has a possible negative effect on the ecosystem, such as chemical
soil contamination, overfertilization, desiccation or soil compaction.
3.16
soil quality TRIAD
procedure for a site-specific ecological risk assessment, whereby the weight of evidence (WOE) (3.20) is made
up of three independent lines of evidence (LoE):
1) a line of evidence based on environmental chemistry with data about concentrations of toxic substances
being converted into the expected effect on the ecosystem;
2) a line of evidence based on measurements of the ecotoxicity in samples of the site with tests; and
3) a line of evidence based on observations of the ecosystem at the site that focus on demonstrating the
effects caused by the contamination
Note 1 to entry: The total of these elements is more than the sum of the separate parts because the burden of proof is
partly based on consistency between the elements.
Note 2 to entry: Descriptions of the approach of the soil quality TRIAD study applied to soil contamination are given in
References [36], [40], [59], [60] and [63], among other places. For the choice of tests, see also ISO 17616.
3.17
type 1 error
judgment that unjustly concludes that there is an unacceptable effect
Note 1 to entry: The term comes from statistics. If there is a type 1 error, the assessment is based not on an actual
unacceptable effect but on chance or a model error. The risk of a type 1 error occurring can be reduced by making
more observations or by improving the model with the ecological aspects and indicators. This latter option can be
achieved by choosing improved conditions and investigation parameters.
3.18
type 2 error
judgment that unjustly concludes that there is no unacceptable effect
Note 1 to entry: The term comes from statistics. If there is a type 2 error, there is actually an unacceptable effect, but
this effect has not been demonstrated because of insufficient or incorrect investigation efforts (too few observations,
unsuitable reference(s) or model errors).
3.19
weighting
rating various investigation results transparently, with equal or different weight being given to the
information concerned
Note 1 to entry: A simple starting position is to give equal weight to the results of the various assessment parameters.
This can be deviated from to devote attention to specific ecological conditions [protected species, key species,
processes, ecosystem services (3.8)], to relatively reliable parameters, or to special test results (giving weight to
observations that show a great effect or giving extra weight to measurements of bioavailable concentrations).

ISO/DIS 19204:2026(en)
3.20
weight of evidence
WOE
weight of evidence of the soil quality TRIAD study which can be used as the basis for taking decisions
responsibly.
Note 1 to entry: In this document, WOE is meant above all in the methodological sense, with all available data obtained
from various lines of evidence-taking being involved in the final conclusion, possibly on the basis of quantitative
weighting. Background information about scaling (3.14), weighting (3.19) and WOE can be found in References [12],
[16], [40], [53], [67], and [72].
Note 2 to entry: With a set budget for the soil quality TRIAD study, the WOE needs to be optimized across investigation
parameters and sample intensity. The assessment criteria (3.2) per parameter and the acceptable statistical error
margin [type 1 error (3.17)] is chosen such that the WOE and acceptance of possible results of the investigation by the
stakeholders (3.1) are maximized.
3.21
soil quality
capability of a type of soil, within natural or managed ecosystem boundaries, to function and provide
ecosystem services
[SOURCE: ISO 18718]
3.22
screening value
soil value which, if exceeded, indicates an assumed potential effect on soil biological structure and function
3.23
retention function
ability of soils/soil materials to adsorb pollutants in such a way that they cannot be mobilized via the water
pathway and translocated into the food chain
Note 1 to entry: The habitat and retention functions include the following soil functions according to ISO 11074:
— control of substance and energy cycles as components of ecosystems;
— basis for the life of plants, animals and man;
— carrier of genetic reservoir;
— basis for the production of agricultural products;
— buffer inhibiting movement of water, contaminants or other agents into the groundwater.
3.24
socio-ecosystemic issues
the issues surrounding socio-ecological systems are seen here as the need to preserve the functioning and
services of these complex systems involving biophysical components (ecology, hydrology, etc.) and societal
components (economy, public policies, institutions, etc.) in constant interaction.
3.25
intrinsic uncertainties
uncertainties of the study related to the choices made in the design of the study protocols (analyses,
equipment, sampling, etc.).
3.26
stochastic uncertainties
uncertainties which essentially reflect the intrinsic variability of the quantity in question (e.g. variations in
earthworm abundance over time). These uncertainties can be better described by obtaining additional data.

ISO/DIS 19204:2026(en)
3.27
epistemic uncertainties
uncertainties which essentially reflect a lack of knowledge. It is possible to reduce these uncertainties by
obtaining additional data.
[SOURCE: ISO 2394:2015, 2.2.19, modified]
3.28
habitat function
ability of soils/soil materials to serve as a habitat for microorganisms, plants, soil living animals and their
interactions (biocenoses)
4 Process overview
The main five steps of performing a soil quality TRIAD according to this document are summarized in
Figure 1. Only the performance of the soil quality TRIAD itself (= execution phase in Reference [43]) is
described.
The method is based on the decision whether and how soil quality shall be assessed at a specific site,
including socio-ecosystemic issues (3.24). (Step I) (also called the phase of the development of a Conceptual
[21][22]
Site Model (CSM). In case this decision is positive, the three lines of evidence, here abbreviated as
chemistry, ecotoxicology and ecology, will be performed (Steps II to IV). Based on an integrative assessment
of the results of the investigation, a decision, e.g. regarding soil remediation, can be made (Step V). This
document refers primarily to Steps I to IV (Step V is not covered in detail in this document). Note that the
extent of the input from stakeholders (left side in Figure 1) and risk assessors (right side in Figure 1) differ
in the different steps — but in any step, input from both sides is required.
NOTE 1 The description of the performance of the soil quality TRIAD as described in this overview can be considered
as the “ideal” version (e.g. the steps and tiers are performed one after another). However, in reality, depending on the
contamination and site properties, the different steps might be performed in a more flexible way. In addition, as soon
as a decision on the ecological risk of a specific site is possible, the process can be stopped.
NOTE 2 Annex A describes the use of bioaccumulation data as an additional tool for site-specific ecological risk
assessment.
ISO/DIS 19204:2026(en)
Key
C chemistry
T ecotoxicology
E ecology
NOTE For details of the central (technical) part of the TRIAD approach, see also Figure 2.
Figure 1 — Diagram of the five steps to be carried out for site-specific ecological risk assessment
(soil quality TRIAD) of soil contamination supporting decision-making with regard to soil quality
5 Uncertainty and weight of evidence
Uncertainty is a key factor in the assessment of ecological risks. Detailed description of uncertainties in a
TRIAD report is mandatory in order to manage them more effectively and also to strengthen the conclusions
of the risk assessment by addressing its obvious limitations. An assessment of ecological risks has various
[65]
uncertainties .
— Communication uncertainty. This form of uncertainty may occur if experts communicate with land users
about ecological risks.
EXAMPLE Translation of a question from a stakeholder (e.g. Is there an ecological risk and how great is
it?) into a scientific question, and communication about the results of the assessment. This uncertainty can be
reduced by good coordination between stakeholders and experts.
— Model uncertainty. Models are used in risk assessment to simplify the local ecosystem (also called site-
specific models). The assessment is based on indicators that are used to describe this simplified system
in quantitative or qualitative terms. The model uncertainty is then linked to the obvious incompleteness
of the model, partly as a result of conscious choice, partly as a result of ignorance. (intrinsic uncertainties)
EXAMPLE A certain plant can be chosen as a model for all the plants in the ecosystem. The chosen plant is
not always an averagely sensitive plant or a sufficiently exposed type of plant and is therefore sometimes not
representative. The model organism does not exclude effects on other species.
— Uncertainty as a result of variability. Uncertainty that results from variations at the sites in time and
space, and from variations and errors in the measurements. (stochastic and epistemic uncertainties)
EXAMPLE An investigation is a snapshot in time, whereas ecosystems change over seasons and years.

ISO/DIS 19204:2026(en)
The soil quality TRIAD advocated in this document, as the content-based and technical framework for the
risk assessment, is based on an optimized weight-of-evidence (WOE) approach. It is made transparent and
quantifiable in the integration of the three independent lines of evidence. If the three independent lines of
evidence point in roughly the same direction (e.g. quantified on a scale from 0 to 1), this is a strong indication
that the model uncertainty is slight and the investigation can be completed. If the three independent lines
of evidence do not point in the same direction, the model uncertainty is still great and a new stage needs to
be gone through to reduce the model uncertainties sufficiently. The model uncertainty can, for example, be
[40]
quantified using a deviation factor .
The soil quality TRIAD is not intended to reduce communication uncertainties, although it can be used for
this. In theory, the results of the soil quality TRIAD are easy to communicate and to summarize in ecological
terms as the biological characteristics of the ecosystem are also involved in the assessment at the site itself.
In practice, the results of the individual lines of evidence shall be communicated too in order to achieve full
understanding of the final results.
6 Soil quality TRIAD performance
6.1 First step: Objective of the investigation (formulating the problem and decision
regarding the need of a site-specific risk assessment)
6.1.1 General approach
The decision whether a TRIAD has to be performed or not for a certain potentially contaminated site is part
of an ecological risk assessment (ERA). Details of such an ERA differ on the national level, but this decision
is based on information compiled in a document often entitled as Conceptual Site Model (CSM). This term
has been introduced in the United Kingdom for the first step of an ecological risk assessment framework for
[21][22][23][24][25][26][27]
contaminants in soil. All available relevant information about the site to be assessed,
e.g. the intended (current and/or future) soil management, the soil ambitions of local government (including
the future use of the land), and the possible ecosystem stress that may be caused by the soil contamination,
is used in this desk study. This step also contains the identification of sources of contamination, ecological
receptors of concern and the potential pathways of exposure. If available, the results of the more detailed
soil investigation provide the scope and the spatial distribution of the soil contamination. If a soil quality
map (e.g. a map of the occurrence of contaminants) is available, this can be an important source of additional
information with regard to the soil quality in the area.
This whole set of information can be divided into three sources:
a) know-how and information provided by the societal, policy and administrative parties (including the
owner of the site);
b) input from experts (e.g. having experience in the specific region, contamination or ecology);
c) data from scientific (field or laboratory) investigations or from the literature.
6.1.2 Decision
The decision about the subject and objective of the investigation should be made as clear as possible and the
investigation objective should be “SMART”:
— Specific: accurately described so that all the people concerned recognize the same objective;
— Measurable: quantifiable units are used for the assessment of the ecological risks;
— Achievable: the objective is recognized by all the parties involved;
— Realistic: financial conditions and other, e.g. legal, restrictions are taken into account;
— Time-related: at the start, it is clear when the investigation objective should be achieved and how any
exceeding of the deadline should be dealt with.

ISO/DIS 19204:2026(en)
In any case, the investigation effort has to be related to the size of the contaminated site as well as the
severity and complexity of the potential ecological risk. The starting point is that the investigation effort is
in real proportion to the size of the problem and the uncertainty that (still) exists.
Note that such a decision depends strongly on national regulations and practices which can be very different
in individual countries.
6.1.3 Stakeholders involved in an ecological risk assessment
Parties with an interest in the soil quality at the site (stakeholders) are the following:
— users (local, regional, national and societal);
— responsible bodies (competent authority, government);
— owners (finance).
Other parties (without a direct interest in the soil quality at that specific site) are the following:
— experts (soil experts, ecologists, ecotoxicologists, risk assessors);
— investigators (responsible for the implementation of the investigation);
— consultants (writers, process consultants, mediators, communication employees).
Several of these parties or roles may also be combined in one person.
At a small investigation site (e.g. a small landfill site), the input of the stakeholders and the experts can
remain limited. At a major investigation site (e.g. the area of a former chemical production plant or a shooting
range), the role of the stakeholders should be broken down into the different interested parties.
NOTE The difference between “small” and “major” investigation sites depends strongly on the specific situation
in a region or country.
At all times, a clear, traceable and transparently reported distinction should be drawn between the role of
the stakeholders and the input of know-how by investigators and consultants, preferably (and dependent
on size) also with tasks being divided among different people. Details of these roles should be fixed in the
investigation plan.
The way stakeholders can be involved and have to be involved depends on the national regulations and
practice.
6.1.4 Independent quali
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