EN ISO 15175:2018

SLOVENSKI STANDARD
01-marec-2019
1DGRPHãþD
SIST EN ISO 15175:2011
SIST ISO 15175:2006
Kakovost tal - Karakterizacija onesnaženih tal v zvezi z varovanjem podzemne
vode (ISO 15175:2018)
Soil quality - Characterization of contaminated soil related to groundwater protection
(ISO 15175:2018)
Bodenbeschaffenheit - Ermittlung von Kennwerten des Bodens hinsichtlich des
Wirkungspfads Boden (ISO 15175:2018)
Qualité du sol - Caractérisation des sols contaminés en relation avec la nappe
phréatique (ISO 15175:2018)
Ta slovenski standard je istoveten z: EN ISO 15175:2018
ICS:
13.080.40 Hidrološke lastnosti tal Hydrological properties of
soils
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 15175
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2018
EUROPÄISCHE NORM
ICS 13.080.40 Supersedes EN ISO 15175:2011
English Version
Soil quality - Characterization of contaminated soil related
to groundwater protection (ISO 15175:2018)
Qualité du sol - Caractérisation des sols pollués en Bodenbeschaffenheit - Ermittlung von Kennwerten des
relation avec la protection des eaux souterraines (ISO Bodens hinsichtlich des Wirkungspfads Boden (ISO
15175:2018) 15175:2018)
This European Standard was approved by CEN on 3 December 2018.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, 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
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 15175:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 15175:2018) has been prepared by Technical Committee ISO/TC 190 "Soil
quality" in collaboration with Technical Committee CEN/TC 345 “Characterization of soils” 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 June 2019, and conflicting national standards shall be
withdrawn at the latest by June 2019.
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.
This document supersedes EN ISO 15175:2011.
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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 15175:2018 has been approved by CEN as EN ISO 15175:2018 without any modification.

INTERNATIONAL ISO
STANDARD 15175
Second edition
2018-12
Soil quality — Characterization
of contaminated soil related to
groundwater protection
Qualité du sol — Caractérisation des sols pollués en relation avec la
protection des eaux souterraines
Reference number
ISO 15175:2018(E)
©
ISO 2018
ISO 15175:2018(E)
© ISO 2018
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 2018 – All rights reserved

ISO 15175:2018(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General . 3
5 Assessment of direct and indirect inputs to groundwater. 5
5.1 General . 5
5.2 Relevant soil processes . 6
5.3 Impact assessment procedures . 7
5.4 Sensitivity and uncertainty analysis, data handling and quality . 9
6 Tier 1 — Simple assessment .11
6.1 General .11
6.2 Site and soil description .11
6.3 Simple assessment of the potential leaching risk .12
7 Tier 2 — Intermediate assessment .13
7.1 General .13
7.2 Sampling .13
7.3 Characterization of soil, water and soil gas .13
7.3.1 General.13
7.3.2 Physical parameters .14
7.3.3 Chemical parameters .14
7.4 Impact assessment .16
7.4.1 General.16
7.4.2 Substance concentration in soil water .16
7.4.3 Amount of transferable substances .17
7.4.4 Degradation of organic contaminants .18
8 Tier 3 — Complex assessment .18
8.1 General .18
8.2 Biological parameters .18
8.3 Isotopic parameters .18
8.4 Geophysical parameters .19
Annex A (informative) Relevant parameters suggested for the physical, chemical and
biological characterization of soil, water and soil gas .20
Annex B (informative) Examples of complex methods for assessing the leaching risk .27
Bibliography .36
ISO 15175:2018(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 will 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 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 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.
This second edition cancels and replaces the first edition (ISO 15175:2004), which has been technically
revised.
The main change concerns the focus on contaminated land management. This second edition suggests a
tiered approach from simple to complex assessment in order to evaluate the impact of soil contamination
of groundwater.
iv © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 15175:2018(E)
Soil quality — Characterization of contaminated soil
related to groundwater protection
1 Scope
This document provides guidance on the principles behind, and main methods for, the evaluation of
sites, soils and soil materials in relation to their role as a source of contamination of groundwater and
their function in retaining, releasing and transforming contaminants. It is focused on contaminated
land management identifying and listing relevant monitoring strategies, methods for sampling, soil
processes and analytical methods.
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 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
aquifer
geological water-bearing formation (bed or stratum) of permeable rock, or unconsolidated material
(e.g. sand and gravels) capable of yielding significant quantities of water
[SOURCE: ISO 5667-11:2009, 3.5]
3.2
contaminant
substance or agent present in the soil (3.10) as a result of human activity
Note 1 to entry: See pollutant (3.7).
Note 2 to entry: There is no assumption in this definition that harm results from the presence of the contaminant.
[SOURCE: ISO 11074:2015, 3.4.6, modified — a new Note 1 to entry has been added and the subsequent
note has been renumbered.]
3.3
dissolved organic carbon
DOC
concentration of organic carbon remaining in solution after filtration and/or centrifugation under
defined conditions
Note 1 to entry: Dissolved organic carbon is expressed in mg/l, g/m .
ISO 15175:2018(E)
3.4
groundwater
water in the saturated zone of an underground geological formation or artificial deposit such as made
ground, e.g. fill material
[SOURCE: ISO 5667-11:2009, 3.9, modified — “and/or unsaturated zone” has been removed.]
3.5
water table
upper boundary surface of the groundwater (3.4)
[SOURCE: ISO 11074:2015, 3.2.4]
3.6
percolating water
infiltrating water that moves downward in the pore space due to gravity
[SOURCE: ISO 11074:2015, 3.2.5]
3.7
pollutant
substance or agent present in the soil (3.10) [or groundwater (3.4)] which, due to its properties, amount
or concentration causes adverse impacts on soil functions (3.11) or soil use
[SOURCE: ISO 11074:2015, 3.4.18, modified — “or soil use” has been added.]
3.8
pore water
water in the pores or cavities within a body of rock or soil (3.10)
[SOURCE: ISO 5667-11:2009, 3.18, modified — “water that fills the pores” has been replaced by “water
in the pores”.]
3.9
risk assessment
process of risk analysis and evaluation of the damaging effects on humans and the environment, with
respect to the nature, extent, and probability of occurrence of these effects
[SOURCE: ISO 11074:2015, 5.2.26, modified — “effects on man” has been replaced by “effects on
humans”.]
3.10
soil
upper layer of the Earth's crust composed of mineral particles, organic matter, water, air and organisms
Note 1 to entry: In a broader civil engineering sense, soil includes topsoil and sub-soil; deposits such as clays,
silts, sands, gravels, cobbles, boulders, and organic matter and deposits such as peat, materials of human origin
such as wastes, ground gas and moisture, and living organisms.
[SOURCE: ISO 11074:2015, 2.1.11, modified — “transformed by weathering and physical/chemical and
biological processes” has been removed.]
3.11
soil function
description of the significance of soils (3.10) to man and the environment
EXAMPLE Control of substance and energy cycles as compartment of ecosystems, basis for the life of plants,
animals, and man, basis for the stability of buildings and roads, basis for the yield of agriculture, horticulture, and
forestry, carrier of genetic reservoir, document of natural history, archaeological and paleoecological document.
[SOURCE: ISO 11074:2015, 3.3.31]
2 © ISO 2018 – All rights reserved

ISO 15175:2018(E)
3.12
soil gas
gas and vapour in the pore spaces of soils (3.10)
[SOURCE: ISO 11074:2015, 2.1.13]
3.13
soil material
excavated soil, dredged materials and soil (3.10) treated to remove or destroy or reduce the
environmental availability of contaminants (3.2)
[SOURCE: ISO 11074:2015, 7.4.16, modified — “materials composed of” removed.]
3.14
soil pores
part of the soil volume, between the solid particles of the soil (3.10)
[SOURCE: ISO 11074:2015, 2.1.14]
3.15
soil water
all water of the unsaturated zone (3.17)
[SOURCE: ISO 11074:2015, 3.2.7, modified — “and saturated” has been removed.]
3.16
total organic carbon
TOC
all carbon present in organic matter
[SOURCE: ISO 11074:2015, 2.1.22]
3.17
unsaturated zone
part of an aquifer (3.1) in which the pore spaces of the formation are not totally filled with water
[SOURCE: ISO 6107-2:2006, 150]
4 General
Soils are of central importance within the water cycle because their storage and filter functions have
a lasting influence on the water balance and groundwater quality. In this context, particular attention
shall be paid to the following functions:
— mechanical filter functions (retention of suspended sludge and contaminant particles);
— chemical filter functions (sorption and mobilization of substances);
— transformation functions (degradation or transformation of substances).
NOTE The liquid phase most commonly consists of solely of water but non-aqueous liquids can sometimes
also be present as a separate phase.
Soil is understood as a porous medium consisting of three phases: the solid phase, the liquid phase and the
gaseous phase. The ratio of these phases and their respective compositions vary widely in time and space.
The assessment of contamination affecting groundwater quality requires a profound understanding
of the governing processes and reactions of potentially toxic compounds in soils. Contaminants are
translocated in all three phases of soils as a function of the properties of the chemicals and the soil.
Hence, strategies for assessing risks to groundwater due to soil contamination should vary with the
contaminants considered, and should take into account those soil properties which mainly govern the
soil's filter, retention, release and transformation functions.
ISO 15175:2018(E)
Vaporous contaminants, essentially volatile organic compounds (VOCs) are likely to migrate in the
unsaturated zone in gaseous form. Knowledge of the soil gas quality in the unsaturated zone allows
detection of contamination before it reaches the saturated zone as well as in the saturated zone.
In addition to considering the properties of the chemicals and the soil governing the behaviour of
contaminants in soils, different ways for contaminants to enter soils should also be evaluated when
designing suitable risk assessment strategies, with respect to contamination of groundwater. Soil and
groundwater contamination can be caused by different sources on different spatial scales, as indicated
in Figure 1.
Key
1 solid waste tip of landfill
2 industrially-polluted “losing” river
3 industrial site drainage
4 leaking storage tanks
5 in-situ sanitation
6 farmyard drainage
7 leaking sewers
8 wastewater lagoons
9 agricultural intensification
Figure 1 — Common sources of groundwater contamination (focus on contaminated land
[1]
management)
On regional and larger scales, soil contamination is caused, for example, by wet and dry atmospheric
deposition. The contamination observed in these cases is generally diffuse and with fairly moderate levels
of contamination. On a local scale, a variety of point sources can cause all kinds and magnitudes of soil
and groundwater contamination. In the case of immiscible contaminants (for example hydrocarbons),
most of the contamination forms a separate liquid phase from water. A fraction is soluble and capable
of migrating to groundwater. In the unsaturated zone, another fraction could be in the vapour phase.
Depending on the relative density in water, the behaviour of the contaminant is very different. Light
non aqueous phase liquids (LNAPL) have a lower density and dense non aqueous phase liquids (DNAPL)
have a higher density than that of water. Most point sources of contamination can also be regarded
as off-site diffuse sources of groundwater contamination. It is evident that different contamination
scenarios as a function of contamination sources and scale demand different investigation strategies
with respect to groundwater impact. Furthermore, groundwater impact assessment depends on the
aquifer system: unconfined or confined and the type of porosity: porous media, fractured media or
karst environment. At present there are no uniform principles for the investigation and evaluation of
contaminated soils and contaminated sites in relation to the protection of water resources.
Investigation strategies may be simple to complex. Simple or qualitative approaches mostly refer
to assessment of, for example, the potential leaching risk of chemicals through the soil towards
groundwater. In contrast to complex or quantitative approaches, the level of actual soil contamination
4 © ISO 2018 – All rights reserved

ISO 15175:2018(E)
is not taken into account. Approaches of this type can also be used, for example, to classify larger areas
with respect to their capability of protecting groundwater resources against contamination, or as an
introductory step in an assessment of an actual contaminated site.
To assess the on-site impact on groundwater resulting from specific soil contamination, quantitative
approaches based on site-specific investigation procedures including laboratory and/or field
measurements have to be used. Laboratory measurements can include physical, chemical and biological
analysis, and leaching tests. Assessments of this kind should also take into account natural background
concentrations of a substance and other natural conditions affecting the impact on the groundwater.
Assessments of impact on groundwater often include a temporal aspect, since the actual impact might
not be measurable at the time of the investigation, but could happen sometime in the future.
Assessments also depend on the purposes of investigations, for example:
— conservation of soil functions in order to prevent groundwater contamination;
— soil and groundwater monitoring;
— risk assessment;
— controlling remediation measures.
A listing of suitable methods is provided in the main part of this document (see Clause 5).
Since the impact on groundwater can lead to impact on surface waters, this aspect can in some cases be
relevant in an overall impact assessment. This issue is not addressed explicitly in this document.
5 Assessment of direct and indirect inputs to groundwater
5.1 General
A prerequisite for the evaluation of the soil-to-groundwater pathway is the determination of the
relevant physical, chemical and biological characteristics of soils and the hydrological characteristics
of the site. It is therefore necessary to collect data for the assessment of the contamination source with
respect to the type and degree of contamination and extent of source(s).
It is also necessary to describe the soil that is impacted by the contamination source, and the factors
affecting the impact on the groundwater, e.g. the geometry, hydraulic conditions and natural chemical
and biologic processes. Indeed, many processes occurring in the soil (physical, chemical and biological
processes) may influence the groundwater impact.
The processes involved are illustrated schematically in Figure 2 and a description of the relevant
parameters is given in Table 1.
ISO 15175:2018(E)
Figure 2 — Schematic diagram illustrating the soil compartment covered by the assessment
[2]
procedure and processes affecting the impact of contamination on groundwater
The types of information needed to describe the relevant soil compartment include pedology (e.g. soil
unit), lithology of parent material, hydrogeology (e.g. permeability), physico-chemical conditions (e.g.
pH) and biological conditions (e.g. substrate availability). The study area of the impact assessment
depends on many factors, such as the following:
— the origin of the contamination: diffuse versus point source;
— the type and characteristics of contaminants (e.g. solubility, persistence);
— the type (e.g. consolidated, unconsolidated, sedimentary/metamorphic/igneous, fractured, karstic,
dual porosity, etc.) and characteristics of the aquifer (e.g. homogeneous/heterogeneous, isotropic/
anisotropic, bedding, jointing, confinement, dispersivity, velocity, etc.);
— the use of the aquifer (e.g. drinking water supply, industrial supply) and relations of the aquifer with
superficial water (e.g. lakes, rivers, etc.).
5.2 Relevant soil processes
Contaminant transport in the unsaturated zone is governed not only by the transport of percolating
water but also by a number of biological, physical and chemical processes. Which of these processes are
to be considered important within a given context depends on the type of contaminants and the actual
soil conditions. An overview of soil and contaminant parameters related to contaminant transport is
given in Table 1.
6 © ISO 2018 – All rights reserved

ISO 15175:2018(E)
Contamination ageing influences different processes in soil: decrease of degradation and mobility,
increase of sorption and viscosity. This parameter should be taken into account for the impact
assessment.
Table 1 — Examples of soil and contaminant parameters related to different processes in soil
Examples of contaminant
Process Examples of soil parameters
parameters
Mass transport of contami- Hydraulic, conductivity, degree of saturation, Solubility, volatility, density,
nants porosity, pore size distribution, soil water- viscosity
retention functions, relative permeability, re-
Adsorption/sorption
sidual saturation, wettability, surface tension,
capillary pressure, tortuosity
Contaminant transport in
water:
Advection Pressure gradient, hydraulic conductivity,
porosity
Dispersion/diffusion Dispersitivity, pore water velocity Diffusion coefficient
Density transport Pore water velocity, soil layering Liquid density
Viscosity
Dispersion, change in density
Preferential flow Pore size distribution, fissure size, macropore Viscosity, density, diffusion
size, connectivity coefficient
Dispersion, change in density
Volatilization Water content, temperature, chemical-phase Vapour pressure, Henry's
content constant
Gas-phase transport Water content, tortuosity, pressure differences Diffusion coefficient
Dissolution of organics Hydraulic conductivity, tortuosity, water content Solubility, composition of
chemical phase
Dissolution of inorganics Hydraulic conductivity, tortuosity, water content Solubility products
Precipitation pH, redox, other components, water content Solubility product, complexa-
tion constant
Complexation pH, ligand concentration, dissolved organic Stability constant of complexes
compound DOC
Ion exchange Cation exchange capacity, ionic strength, other Valence, degree of hydratization
cations, pH
Sorption of organics pH, organic matter content, clay content and Octanol/water distribution
mineralogy, specific surface area coefficient, sorption coefficient
Sorption of inorganics pH, organic matter content, clay content and Sorption coefficient
mineralogy, specific surface area, non-crystal-
line (short-range ordered) oxide and hydrous
oxide gels
Degradation
Abiotic Redox, pH, temperature Presence of primary susbtrate,
degradability, toxicity to mi-
Biotic Microorganisms, redox, substrate, pH, tempera-
croorganisms
ture, water content
5.3 Impact assessment procedures
In order to complete a description of the source and the soil, it is necessary to develop:
— strategies for evaluation of site-specific parameters;
— sampling strategies;
ISO 15175:2018(E)
— analytical and testing strategies;
— for each site and/or media (soil, groundwater, soil gas) that influences the impact on the groundwater.
These strategies should be determined on the basis of:
— history of the site or area;
— available data and/or results of previous investigations;
— the nature of any process-based treatment methods that have been applied to the soil;
— the intended use of the site.
To optimize the actual need for information in relation to the costs and time demanded for the
investigations in the field and laboratory, the assessment should be carried out following a tiered
approach (see Figure 3 which displays a generic approach which can be amended when necessary).
The impact assessment is often an iterative procedure, each tier being a more refined version of the
description of the problem and each leading to a more detailed basis for decision-making, as to the
necessity of remedial action in the form of site clean-up, land-use restrictions, etc. (see Tier 2 on
Figure 3).
Figure 3 — Graduated approach for impact assessment
8 © ISO 2018 – All rights reserved

ISO 15175:2018(E)
Investigations of contaminated sites are usually only carried out where contamination is expected.
[4]
Thus, guidance given in ISO 18400-203 can be used. The area of interest may provide elements
forming a basis for decision-making and for determining if a site should be remediated.
The first tier requires a preliminary investigation (desk study and site reconnaissance) (see Clause 6),
such as collecting information about known or suspected contamination hot-spots and the range of
expected contaminants. In the first tier, the assessment identifies presence of potential source-
pathway-receptor linkages.
If this proves inconclusive, it could be necessary to locate contamination hot-spots via a targeted
exploratory investigation (Tier 2). This should include the determination of total and pseudo-total
concentrations of substances. If evidence of increased concentrations of contaminants can be deduced
from the orientated investigations, then pathway-specific investigations are necessary. The risk of
groundwater contamination in the saturated zone can, in general, be derived from the concentration
and amount of substances in water in the unsaturated zone (e.g. infiltration, capillary, perched). In some
cases, it may be more important to consider the amounts of contaminants instead of the concentrations,
which may be very high in a small spot, without posing a large risk of groundwater contamination.
Evaluation of the exposure pathway of soil to groundwater within the framework of a second-tier risk
assessment requires evaluation of the concentration of substances in the percolation water which enter
the groundwater.
Within the framework of a detailed investigation, it may be necessary to consider, in addition, the
volumes of transferable substances, potentially mobile fractions and other parameters.
The assessment of a groundwater contamination risk resulting from soil contamination can be
performed at different levels of complexity. The more data available, the more processes can be taken
into account in a risk assessment model. An example procedure is given in Annex B.
NOTE Often, the reports presenting the results of assessments are scrutinized by regulators and other
interested parties, including the general public. It is important, therefore, that such reports are of a high technical
standard but also take into account the diverse and often non-technical readership. Therefore, tabular summaries,
graphical and other means can be used to present the data in ways that make the data and conclusions as easy as
is practicable to assimilate and assess.
5.4 Sensitivity and uncertainty analysis, data handling and quality
The purpose of characterizing soil (or other media) as suggested in this document is usually to enable
site assessment with respect to impact on groundwater. This document provides guidance on the types
of data that might be required in an assessment, and indicates for which parameters or procedures
there are international or national standards available. The assessor shall choose those parameters
that are appropriate to the task in hand.
Estimations of uncertainty are of crucial importance to risk assessments, as they provide a measure
of confidence in the site investigation data and ultimately the final outcome of the risk assessment.
Uncertainties typically concern:
— the extent to which the contaminant data from single samples are spatially representative of the
site conditions;
— the extent to which sampling techniques are adequate to ensure that a sample is representative of
the site conditions at the point where it was taken;
— the extent to which analytical data reflects the actual characteristics (concentrations, form/state,
mobility, etc.) of the contaminants present;
— the extent to which the pedological, geological, hydrogeological conditions at the site are understood;
— the ways in which the contaminants may behave in the environmental setting of the site and
surrounding areas (fate and transport issues);
ISO 15175:2018(E)
— the extent to which behaviour of the receptors potentially at risk under the particular circumstances
can affect the risk estimates;
— how the receptors can be affected by the contaminants, and what role the different receptor
characteristics play in this.
A sensitivity and uncertainties analysis should be conducted on each parameter to determine its
influence on the results of the simulations and predictions settings. Furthermore, this analysis allows
us to understand the contribution to the overall uncertainty of each parameter tested.
The model is validated by comparing the results of the predictive simulation and measurements in the
field. The construction and calibration of a model are validated iteratively by comparing the results of
measurements and simulation results.
Uncertainty accompanying an estimate of, for example, concentrations of contaminants in percolation
water can originate from various sources. Generally, sources of uncertainty can be differentiated
between knowledge or informational uncertainty and natural variability. Natural variability as
a property of nature cannot be reduced while informational uncertainty can to some extent be
counteracted by increased sampling or measurement efforts. Informational uncertainty can be due
to uncertain data quality, such as measurement errors or incomplete data, or due to uncertain model
structure and parameters. Uncertainty in model structure is the result of simplifications, assumptions
or errors in the formulation of the model. Model uncertainty can also result from uncertainty in the
model parameters produced in the course of model fitting.
For the problem of contaminants percolating from soils to groundwater, it is important to recognize that
the processes forming the soil are physical, chemical and biological and obey physicochemical laws in a
highly nonlinear way. Technically, all variations of contaminant concentrations in the percolating water
are deterministic in the sense that they are a result of soil characteristics governing relevant sorption,
decay or other processes. However the sensitivity of these processes to small variations in governing
soil properties produces some random error, which in turn leads to undeterminable variations in the
dissolved phase. Random error causes stochastic uncertainty leading to imprecision, while uncertainty
in model structure (leading the model to incorrectly reproduce the process in question) causes
deterministic uncertainty leading to inaccuracy.
Before any judgement can be made about impact on groundwater, the sufficiency of data on soil, soil gas
and groundwater to be used should be evaluated. The data shall be sufficient in terms of:
— type;
— quantity;
— analytical/testing quality.
In the context of data quality, it is essential to:
— define the objectives of the investigation;
— establish a sampling strategy;
— establish an analytical and testing strategy taking into account the guidance in this document and
other relevant International Standards;
— set data quality objectives consistent with the assessment procedure to be used.
[5]
NOTE Guidance on sampling strategies for soil quality is given in, for example, ISO 18400-104 , for soil gas
[5] [7]
in, for example, ISO 18400-204 and for groundwater in, for example, ISO 5667-11 .
It is essential to have sufficient data. The confidence that can be attached to any judgements made if
no greater than the confidence there is in the representativeness of the data. For example, confidence
following a site-specific risk assessment or through comparison with the requirements of authoritative
guidance such as generic assessment criteria or environmental quality standards. The requirements of
such guidance regarding sampling shall always be followed.
10 © ISO 2018 – All rights reserved

ISO 15175:2018(E)
The assessor needs to bear in mind the disproportionate costs and time delays that can result if it is
necessary to carry out an additional sampling exercise if, for example, a particular parameter is not
determined when the opportunity is available.
Care shall be taken in deciding what statistical expression(s) of the data are to be used in the assessment,
as this may affect the choice of sampling procedures. For groundwater impact investigations, a
statistic such as the “95 % upper confidence level of the mean” or the “maximum observed value” is
recommended (See Reference [8]).
The quality of the data to be used shall be ensured by some or all of the following:
— setting formal data quality objectives (e.g. for accuracy, reproducibility, etc.);
— using standardized analytical and testing methods such as those listed in this document or, where
International Standard methods are not available, those published by national standardization or
equivalent bodies;
— using laboratories using methods accredited under regional schemes.
6 Tier 1 — Simple assessment
6.1 General
[3]
The first tier includes preliminary investigations as defined, for example, in ISO 18400-202 based
on desktop investigations and site reconnaissance with the aim of carrying out an initial impact
assessment. This tier includes delineation of the soil geometry, soil unit and hydrological conditions on
the basis of general knowledge of the area, possibly supplemented with some field data concerning local
conditions. Specific hydraulic parameters (e.g. hydraulic conductivity, water retention characteristics
and infiltration rate) can also be estimated from relevant literature (pedo-transfer functions and/or
databases). The presence of contaminants and other substances of interest (e.g. possible presence of
naturally occurring substances that might leach) and their likely concentrations are estimated on basis
of site history and any available analyses of soil and water samples and/or soil-gas measurements. The
relevant transport and decomposition processes are approximated from data related to the relevant
soil conditions and contaminants retrieved from the literature. The mobility of inorganic contaminants
can be estimated by assessing the soil/water partition coefficient (K ) (see Reference [9]). For organic
d
compounds, the soil organic carbon-water partitioning coefficient (K ) should be estimated preferably
oc
with passive sampling given in References [10] and [11].
Relevant parameters required for the physical and chemical characterization are listed in Annex A
together with suitable methods for their determination or evaluation.
If the Tier 1 assessment indicates a need for a more detailed assessment, the Tier 2 assessment should
be carried out. The relevant investigations consisting of sampling, chemical analysis and field tests are
planned on the basis of Tier 1.
6.2 Site and soil description
The assessment of the potential impacts of contaminated soil on groundwater requires general
information about the site under investigation. The most relevant parameters for a site-description are
[3]
listed in Table 2. For example, ISO 18400-202 could be applied. The scale at which this information
may be collected, and the degree of detail that is required, is closely related to the objective of the
investigation which primarily depends on the anticipated nature and distribution of contamination (see
[4]
ISO 18
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