ASTM E1689-95(2008)

Standard Guide for Developing Conceptual Site Models for Contaminated Sites

SIGNIFICANCE AND USE
p>The information gained through the site investigation is used to characterize the physical, biological, and chemical systems existing at a site. The processes that determine contaminant releases, contaminant migration, and environmental receptor exposure to contaminants are described and integrated in a conceptual site model.
Development of this model is critical for determining potential exposure routes (for example, ingestion and inhalation) and for suggesting possible effects of the contaminants on human health and the environment. Uncertainties associated with the conceptual site model need to be identified clearly so that efforts can be taken to reduce these uncertainties to acceptable levels. Early versions of the model, which are usually based on limited or incomplete information, will identify and emphasize the uncertainties that should be addressed.
The conceptual site model is used to integrate all site information and to determine whether information including data are missing (data gaps) and whether additional information needs to be collected at the site. The model is used furthermore to facilitate the selection of remedial alternatives and to evaluate the effectiveness of remedial actions in reducing the exposure of environmental receptors to contaminants.
This guide is not meant to replace regulatory requirements for conducting environmental site characterizations at contaminated (including radiologically contaminated) sites. It should supplement existing guidance and promote a uniform approach to developing conceptual site models.
This guide is meant to be used by all those involved in developing conceptual site models. This should ideally include representatives from all phases of the investigative and remedial process, for example, preliminary assessment, remedial investigation, baseline human health and ecological risk assessments, and feasibility study. The conceptual site model should be used to enable experts from all disciplines to c...
SCOPE
1.1 This guide is intended to assist in the development of conceptual site models to be used for the following: (1) integration of technical information from various sources, (2) support the selection of sample locations for establishing background concentrations of substances, (3) identify data needs and guide data collection activities, and (4) evaluate the risk to human health and the environment posed by a contaminated site. This guide generally describes the major components of conceptual site models, provides an outline for developing models, and presents an example of the parts of a model. This guide does not provide a detailed description of a site-specific conceptual site model because conditions at contaminated sites can vary greatly from one site to another.
1.2 The values stated in either inch-pound or SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This guide is intended to apply to any contaminated site.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Jan-2008
• ICS: 13.030.30 - Special wastes
• Technical Committee: E50 - Environmental Assessment, Risk Management and Corrective Action
• Drafting Committee: E50.05 - Environmental Risk Management

Relations

• Referred By: ASTM E3240-20 - Standard Guide for Risk-Based Corrective Action for Contaminated Sediment Sites
• Effective Date: 01-Feb-2008
• Referred By: ASTM E3344-22 - Standard Guide for Selection of Background Reference Areas for Determination of Representative Sediment Background Concentrations
• Effective Date: 01-Feb-2008
• Referred By: ASTM E3249-21 - Standard Guide for Remedial Action Resiliency to Climate Impacts
• Effective Date: 01-Feb-2008
• Referred By: ASTM E3358-23a - Standard Guide for Per- and Polyfluoroalkyl Substances Site Screening and Initial Characterization
• Effective Date: 01-Feb-2008
• Referred By: ASTM E2081-22 - Standard Guide for Risk-Based Corrective Action
• Effective Date: 01-Feb-2008
• Referred By: ASTM E2616-09(2020) - Standard Guide for Remedy Selection Integrating Risk-Based Corrective Action and Non-Risk Considerations
• Effective Date: 01-Feb-2008
• Referred By: ASTM E3228-19 - Standard Guide for Environmental Knowledge Management
• Effective Date: 01-Feb-2008
• Referred By: ASTM E2385-11(2016) - Standard Guide for Estimating Wildlife Exposure Using Measures of Habitat Quality
• Effective Date: 01-Feb-2008
• Referred By: ASTM E2435-05(2020) - Standard Guide for Application of Engineering Controls to Facilitate Use or Redevelopment of Chemical-Affected Properties
• Effective Date: 01-Feb-2008
• Referred By: ASTM E3300-21 - Standard Guide for NAPL Mobility and Migration in Sediment— Evaluating Ebullition and Associated NAPL/Contaminant Transport
• Effective Date: 01-Feb-2008
• Referred By: ASTM E1943-98(2015) - Standard Guide for Remediation of Ground Water by Natural Attenuation at Petroleum Release Sites
• Effective Date: 01-Feb-2008
• Referred By: ASTM E2552-23 - Standard Guide for Assessing the Environmental and Human Health Impacts of New Compounds for Military Use
• Effective Date: 01-Feb-2008
• Referred By: ASTM E3382-23 - Standard Guide for Developing Representative Background Concentrations at Sediment Sites — Framework Overview, Including Conceptual Site Model Considerations
• Effective Date: 01-Feb-2008
• Referred By: ASTM E3242-20 - Standard Guide for Determination of Representative Sediment Background Concentrations
• Effective Date: 01-Feb-2008
• Referred By: ASTM E3163-18 - Standard Guide for Selection and Application of Analytical Methods and Procedures Used during Sediment Corrective Action
• Effective Date: 01-Feb-2008

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E1689 − 95(Reapproved 2008)
Standard Guide for
Developing Conceptual Site Models for Contaminated Sites
This standard is issued under the fixed designation E1689; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Guidance for Data Useability in Risk Assessment (Part B),
OSWER Directive 9285.7-09B, May 1992
1.1 This guide is intended to assist in the development of
Guidance for Conducting Remedial Investigations and Fea-
conceptual site models to be used for the following: (1)
sibility Studies Under CERCLA, OSWER Directive
integration of technical information from various sources, (2)
9355.3-01, October 1988
support the selection of sample locations for establishing
background concentrations of substances, (3) identify data
3. Terminology
needs and guide data collection activities, and (4 ) evaluate the
risk to human health and the environment posed by a contami-
3.1 Definitions:
nated site. This guide generally describes the major compo-
3.1.1 background concentration, n—the concentration of a
nents of conceptual site models, provides an outline for
substance in ground water, surface water, air, sediment, or soil
developing models, and presents an example of the parts of a
at a source(s) or nearby reference location, and not attributable
model. This guide does not provide a detailed description of a
to the source(s) under consideration. Background samples may
site-specific conceptual site model because conditions at con-
be contaminated, either by naturally occurring or manmade
taminated sites can vary greatly from one site to another.
sources, but not by the source(s) in question.
1.2 The values stated in either inch-pound or SI units are to
3.1.2 conceptual site model, n—for the purpose of this
be regarded as the standard. The values given in parentheses
guide, a written or pictorial representation of an environmental
are for information only.
system and the biological, physical, and chemical processes
that determine the transport of contaminants from sources
1.3 Thisguideisintendedtoapplytoanycontaminatedsite.
through environmental media to environmental receptors
1.4 This standard does not purport to address all of the
within the system.
safety concerns, if any, associated with its use. It is the
3.1.3 contaminant, n—any substance, including any radio-
responsibility of the user of this standard to establish appro-
logical material, that is potentially hazardous to human health
priate safety and health practices and determine the applica-
or the environment and is present in the environment at
bility of regulatory limitations prior to use.
concentrations above its background concentration.
2. Referenced Documents
3.1.4 contaminant release, n—movement of a substance
from a source into an environmental medium, for example, a
2.1 ASTM Standards:
leak, spill, volatilization, runoff, fugitive dust emission, or
D2216 Test Methods for Laboratory Determination of Water
leaching.
(Moisture) Content of Soil and Rock by Mass
2.2 EPA Documents: 3.1.5 environmental receptor, n—humans and other living
organisms potentially exposed to and adversely affected by
Guidance for Data Useability in Risk Assessment (Part A)
Final,Publication9285.7-09A, PB92-963356,April1992 contaminants because they are present at the source(s) or along
contaminant migration pathways.
3.1.6 environmental transport, n—movement of a chemical
ThisguideisunderthejurisdictionofASTMCommitteeE50onEnvironmental
or physical agent in the environment after it has been released
Assessment, Risk Management and CorrectiveAction and is the direct responsibil-
from a source to an environmental medium, for example,
ity of Subcommittee E50.05 on Environmental Risk Management.
Current edition approved Feb. 1, 2008. Published February 2008. Originally movement through the air, surface water, ground water, soil,
ε1
approved in 1995. Last previous edition approved in 2003 as E1689–95(2003) .
sediment, or food chain.
DOI: 10.1520/E1689-95R08.
3.1.7 exposure route, n—the process by which a contami-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
nant or physical agent in the environment comes into direct
Standards volume information, refer to the standard’s Document Summary page on
contact with the body, tissues, or exchange boundaries of an
the ASTM website.
environmental receptor organism, for example, ingestion,
Available from Standardization Documents Order Desk, Bldg 4 Section D, 700
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS. inhalation, dermal absorption, root uptake, and gill uptake.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1689 − 95 (2008)
3.1.8 migration pathway, n—the course through which con- usually based on limited or incomplete information, will
taminants in the environment may move away from the identify and emphasize the uncertainties that should be ad-
source(s) to potential environmental receptors. dressed.
3.1.9 source, n—the location from which a contaminant(s) 5.3 The conceptual site model is used to integrate all site
information and to determine whether information including
has entered or may enter a physical system.Aprimary source,
such as a location at which drums have leaked onto surface data are missing (data gaps) and whether additional informa-
tion needs to be collected at the site. The model is used
soils, may produce a secondary source, such as contaminated
soils; sources may hence be primary or secondary. furthermore to facilitate the selection of remedial alternatives
and to evaluate the effectiveness of remedial actions in reduc-
4. Summary of Guide ing the exposure of environmental receptors to contaminants.
5.4 This guide is not meant to replace regulatory require-
4.1 The six basic activities associated with developing a
ments for conducting environmental site characterizations at
conceptual site model (not necessarily listed in the order in
contaminated (including radiologically contaminated) sites. It
which they should be addressed) are as follows: (1) identifi-
should supplement existing guidance and promote a uniform
cation of potential contaminants; (2) identification and charac-
approach to developing conceptual site models.
terization of the source(s) of contaminants; (3) delineation of
potential migration pathways through environmental media,
5.5 This guide is meant to be used by all those involved in
such as ground water, surface water, soils, sediment, biota, and
developing conceptual site models. This should ideally include
air; (4) establishment of background areas of contaminants for
representatives from all phases of the investigative and reme-
each contaminated medium; (5) identification and character-
dial process, for example, preliminary assessment, remedial
ization of potential environmental receptors (human and eco-
investigation, baseline human health and ecological risk
logical); and (6) determination of the limits of the study area or
assessments, and feasibility study. The conceptual site model
system boundaries.
should be used to enable experts from all disciplines to
communicate effectively with one another, resolve issues
4.2 The complexity of a conceptual site model should be
concerning the site, and facilitate the decision-making process.
consistent with the complexity of the site and available data.
The development of a conceptual site model will usually be 5.6 The steps in the procedure for developing conceptual
iterative. Model development should start as early in the site sitemodelsincludeelementssometimesreferredtocollectively
investigation process as possible. The model should be refined as site characterization. Although not within the scope of this
and revised throughout the site investigation process to incor- guide, the conceptual site model can be used during site
porate additional site data. The final model should contain remediation.
sufficient information to support the development of current
6. Procedure
and future exposure scenarios.
6.1 Assembling Information—Assemble historical and cur-
4.3 The concerns of ecological risk assessment are different
rent site-related information from maps, aerial images, cross
from those of human-health risk assessment, for example,
sections, environmental data, records, reports, studies, and
important migration pathways, exposure routes, and environ-
other information sources. A visit(s) to the site by those
mental receptors. These differences are usually sufficient to
preparing the conceptual site model is recommended highly.
warrant separate descriptions and representations of the con-
The quality of the information being assembled should be
ceptual site model in the human health and ecological risk
evaluated, preferably including quantitative methods, and the
assessment reports. There will be elements of the conceptual
decision to use the information should be based on the data’s
site model that are common to both representations, however,
meeting objective qualitative and quantitative criteria. For
and the risk assessors should develop these together to ensure
more information on assessing the quality and accuracy of
consistency.
data, see Guidance for Data Useability in Risk Assessment
(Part A) and Guidance for Data Useability in Risk Assessment
5. Significance and Use
(Part B). Methods used for obtaining analytical data should be
described, and sources of information should be referenced. A
5.1 The information gained through the site investigation is
conceptualsitemodelshouldbedevelopedforeverysiteunless
used to characterize the physical, biological, and chemical
there are multiple sites in proximity to one another such that it
systems existing at a site. The processes that determine
is not possible to determine the individual source or sources of
contaminant releases, contaminant migration, and environmen-
contamination. Sites may be aggregated in that case. A
tal receptor exposure to contaminants are described and inte-
conceptual model should then be developed for the aggregate.
grated in a conceptual site model.
6.2 Identifying Contaminants—Identify contaminants in the
5.2 Development of this model is critical for determining
ground water, surface water, soils, sediments, biota, and air. If
potential exposure routes (for example, ingestion and inhala-
nocontaminantsarefound,theconceptualsitemodelshouldbe
tion) and for suggesting possible effects of the contaminants on
used to help document this finding.
human health and the environment. Uncertainties associated
with the conceptual site model need to be identified clearly so 6.3 Establishing Background Concentrations of
that efforts can be taken to reduce these uncertainties to Contaminants—Background samples serve three major func-
acceptable levels. Early versions of the model, which are tions: (1) to establish the range of concentrations of an analyte
E1689 − 95 (2008)
attributable to natural occurrence at the site; (2) to establish the hydrology of the site. Other fate and transport phenomena that
range of concentrations of an analyte attributable to source(s) should be considered include hydrodynamic dispersion, inter-
other than the source(s) under consideration; and (3) to help phase transfers of contaminants, and retardation. Movement
establish the extent to which contamination exceeds back- through the vadose zone should be considered.
ground levels.
6.5.2 Surface Water and Sediment Pathway—This pathway
6.3.1 Theconceptualsitemodelshouldincludethenaturally
should always be investigated in the following situations: (1)a
occurring concentrations of all contaminants found at the site.
perennial body of water (river, lake, continuous stream, drain-
The number and location of samples needed to establish
age ditch, etc.) is in direct contact with, or is potentially
background concentrations in each medium will vary with
contaminated by a source or contaminated area, (2) an unin-
specific site conditions and requirements. The model should
terrupted pathway exists from a source or contaminated area to
include sufficient background samples to distinguish contami-
the surface water, (3) sampling and analysis of the surface
nation attributable to the source(s) under consideration from water body or sediments indicate contaminant concentrations
naturally occurring or nearby anthropogenic contamination.
substantially above background, (4) contaminated ground wa-
The procedures mentioned in 6.2 and 6.3 are sometimes ter or surface water runoff is known or suspected to discharge
grouped under the general heading of contaminant assessment
to a surface water body, and (5) under arid conditions in which
and may be performed as a separate activity prior to the ephemeral drainage may convey contaminants to downstream
development of a conceptual site model.
points of exposure.
6.5.3 Air Pathway—Contaminant transport through the air
6.4 Characterizing Sources—At a minimum, the following
pathway should be evaluated for contaminants in the surface
source characteristics should be measured or estimated for a
soil, subsurface soil, surface water, or other media capable of
site:
releasing gasses or particulate matter to the air. The migration
6.4.1 Source location(s), boundaries, and volume(s).
of contaminants from air to other environmental compartments
Sources should be located accurately on site maps. Maps
should be considered, for example, deposition of particulates
should include a scale and direction indicator (for example,
resulting from incineration onto surface waters and soil.
north arrow). They should furthermore show where the
6.5.4 Soil Contact Pathway—Contaminated soils that may
source(s) is located in relationship to the property boundaries.
come into direct contact with human or ecological receptors
6.4.2 The potentially hazardous constituents and their con-
should be investigated. This includes direct contact with
centrations in media at the source.
chemicals through dermal absorption and direct exposure to
6.4.3 The time of initiation, duration, and rate of contami-
gamma radiation from radioactively contaminated soil. There
nant release from the source.
is a potential for human and ecological receptors to be exposed
6.5 Identifying Migration Pathways—Potential migration
to contaminants at different soil depths (for example, humans
pathways through ground water, s
...