1、Designation: E 1689 95 (Reapproved 2008)Standard Guide forDeveloping Conceptual Site Models for Contaminated Sites1This standard is issued under the fixed designation E 1689; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide is intended to assist in the development ofconceptual site models to be used for the following: (1)int
3、egration of technical information from various sources, (2)support the selection of sample locations for establishingbackground concentrations of substances, (3) identify dataneeds and guide data collection activities, and (4) evaluate therisk to human health and the environment posed by a contami-n
4、ated site. This guide generally describes the major compo-nents of conceptual site models, provides an outline fordeveloping models, and presents an example of the parts of amodel. This guide does not provide a detailed description of asite-specific conceptual site model because conditions at con-ta
5、minated sites can vary greatly from one site to another.1.2 The values stated in either inch-pound or SI units are tobe regarded as the standard. The values given in parenthesesare for information only.1.3 This guide is intended to apply to any contaminated site.1.4 This standard does not purport to
6、 address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 2216 Te
7、st Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by Mass2.2 EPA Documents:3Guidance for Data Useability in Risk Assessment (Part A)Final, Publication 9285.7-09A, PB 92-963356, April1992Guidance for Data Useability in Risk Assessment (Part B),OSWER Directive 9285.
8、7-09B, May 1992Guidance for Conducting Remedial Investigations and Fea-sibility Studies Under CERCLA, OSWER Directive9355.3-01, October 19883. Terminology3.1 Definitions:3.1.1 background concentration, nthe concentration of asubstance in ground water, surface water, air, sediment, or soilat a source
9、(s) or nearby reference location, and not attributableto the source(s) under consideration. Background samples maybe contaminated, either by naturally occurring or manmadesources, but not by the source(s) in question.3.1.2 conceptual site model, nfor the purpose of thisguide, a written or pictorial
10、representation of an environmentalsystem and the biological, physical, and chemical processesthat determine the transport of contaminants from sourcesthrough environmental media to environmental receptorswithin the system.3.1.3 contaminant, nany substance, including any radio-logical material, that
11、is potentially hazardous to human healthor the environment and is present in the environment atconcentrations above its background concentration.3.1.4 contaminant release, nmovement of a substancefrom a source into an environmental medium, for example, aleak, spill, volatilization, runoff, fugitive
12、dust emission, orleaching.3.1.5 environmental receptor, nhumans and other livingorganisms potentially exposed to and adversely affected bycontaminants because they are present at the source(s) or alongcontaminant migration pathways.3.1.6 environmental transport, nmovement of a chemicalor physical ag
13、ent in the environment after it has been releasedfrom a source to an environmental medium, for example,movement through the air, surface water, ground water, soil,sediment, or food chain.1This guide is under the jurisdiction of ASTM Committee E47 on BiologicalEffects and Environmental Fate and is th
14、e direct responsibility of SubcommitteeE47.05 on Risk Assessment, Communication and Management.Current edition approved Feb. 1, 2008. Published February 2008. Originallyapproved in 1995. Last previous edition approved in 2003 as E 168995(2003)e1.2For referenced ASTM standards, visit the ASTM website
15、, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Standardization Documents Order Desk, Bldg 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-509
16、4, Attn: NPODS.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.7 exposure route, nthe process by which a contami-nant or physical agent in the environment comes into directcontact with the body, tissues, or exchange boundaries of
17、 anenvironmental receptor organism, for example, ingestion, in-halation, dermal absorption, root uptake, and gill uptake.3.1.8 migration pathway, nthe course through whichcontaminants in the environment may move away from thesource(s) to potential environmental receptors.3.1.9 source, nthe location
18、from which a contaminant(s)has entered or may enter a physical system. A primary source,such as a location at which drums have leaked onto surfacesoils, may produce a secondary source, such as contaminatedsoils; sources may hence be primary or secondary.4. Summary of Guide4.1 The six basic activitie
19、s associated with developing aconceptual site model (not necessarily listed in the order inwhich they should be addressed) are as follows: (1) identifi-cation of potential contaminants; (2) identification and charac-terization of the source(s) of contaminants; (3) delineation ofpotential migration p
20、athways through environmental media,such as ground water, surface water, soils, sediment, biota, andair; (4) establishment of background areas of contaminants foreach contaminated medium; (5) identification and character-ization of potential environmental receptors (human and eco-logical); and (6) d
21、etermination of the limits of the study area orsystem boundaries.4.2 The complexity of a conceptual site model should beconsistent with the complexity of the site and available data.The development of a conceptual site model will usually beiterative. Model development should start as early in the si
22、teinvestigation process as possible. The model should be refinedand revised throughout the site investigation process to incor-porate additional site data. The final model should containsufficient information to support the development of currentand future exposure scenarios.4.3 The concerns of ecol
23、ogical risk assessment are differentfrom those of human-health risk assessment, for example,important migration pathways, exposure routes, and environ-mental receptors. These differences are usually sufficient towarrant separate descriptions and representations of the con-ceptual site model in the h
24、uman health and ecological riskassessment reports. There will be elements of the conceptualsite model that are common to both representations, however,and the risk assessors should develop these together to ensureconsistency.5. Significance and Use5.1 The information gained through the site investig
25、ation isused to characterize the physical, biological, and chemicalsystems existing at a site. The processes that determinecontaminant releases, contaminant migration, and environmen-tal receptor exposure to contaminants are described and inte-grated in a conceptual site model.5.2 Development of thi
26、s model is critical for determiningpotential exposure routes (for example, ingestion and inhala-tion) and for suggesting possible effects of the contaminants onhuman health and the environment. Uncertainties associatedwith the conceptual site model need to be identified clearly sothat efforts can be
27、 taken to reduce these uncertainties toacceptable levels. Early versions of the model, which areusually based on limited or incomplete information, willidentify and emphasize the uncertainties that should be ad-dressed.5.3 The conceptual site model is used to integrate all siteinformation and to det
28、ermine whether information includingdata are missing (data gaps) and whether additional informa-tion needs to be collected at the site. The model is usedfurthermore to facilitate the selection of remedial alternativesand to evaluate the effectiveness of remedial actions in reduc-ing the exposure of
29、environmental receptors to contaminants.5.4 This guide is not meant to replace regulatory require-ments for conducting environmental site characterizations atcontaminated (including radiologically contaminated) sites. Itshould supplement existing guidance and promote a uniformapproach to developing
30、conceptual site models.5.5 This guide is meant to be used by all those involved indeveloping conceptual site models. This should ideally includerepresentatives from all phases of the investigative and reme-dial process, for example, preliminary assessment, remedialinvestigation, baseline human healt
31、h and ecological risk as-sessments, and feasibility study. The conceptual site modelshould be used to enable experts from all disciplines tocommunicate effectively with one another, resolve issuesconcerning the site, and facilitate the decision-making process.5.6 The steps in the procedure for devel
32、oping conceptualsite models include elements sometimes referred to collectivelyas site characterization. Although not within the scope of thisguide, the conceptual site model can be used during siteremediation.6. Procedure6.1 Assembling InformationAssemble historical and cur-rent site-related inform
33、ation from maps, aerial images, crosssections, environmental data, records, reports, studies, andother information sources. A visit(s) to the site by thosepreparing the conceptual site model is recommended highly.The quality of the information being assembled should beevaluated, preferably including
34、 quantitative methods, and thedecision to use the information should be based on the datasmeeting objective qualitative and quantitative criteria. Formore information on assessing the quality and accuracy ofdata, see Guidance for Data Useability in Risk Assessment(Part A) and Guidance for Data Useab
35、ility in Risk Assessment(Part B). Methods used for obtaining analytical data should bedescribed, and sources of information should be referenced. Aconceptual site model should be developed for every site unlessthere are multiple sites in proximity to one another such that itis not possible to determ
36、ine the individual source or sources ofcontamination. Sites may be aggregated in that case. Aconceptual model should then be developed for the aggregate.6.2 Identifying ContaminantsIdentify contaminants in theground water, surface water, soils, sediments, biota, and air. Ifno contaminants are found,
37、 the conceptual site model should beused to help document this finding.6.3 Establishing Background Concentrations ofContaminantsBackground samples serve three major func-tions: (1) to establish the range of concentrations of an analyteE 1689 95 (2008)2attributable to natural occurrence at the site;
38、(2) to establish therange of concentrations of an analyte attributable to source(s)other than the source(s) under consideration; and (3) to helpestablish the extent to which contamination exceeds back-ground levels.6.3.1 The conceptual site model should include the naturallyoccurring concentrations
39、of all contaminants found at the site.The number and location of samples needed to establishbackground concentrations in each medium will vary withspecific site conditions and requirements. The model shouldinclude sufficient background samples to distinguish contami-nation attributable to the source
40、(s) under consideration fromnaturally occurring or nearby anthropogenic contamination.The procedures mentioned in 6.2 and 6.3 are sometimesgrouped under the general heading of contaminant assessmentand may be performed as a separate activity prior to thedevelopment of a conceptual site model.6.4 Cha
41、racterizing SourcesAt a minimum, the followingsource characteristics should be measured or estimated for asite:6.4.1 Source location(s), boundaries, and volume(s).Sources should be located accurately on site maps. Mapsshould include a scale and direction indicator (for example,north arrow). They sho
42、uld furthermore show where thesource(s) is located in relationship to the property boundaries.6.4.2 The potentially hazardous constituents and their con-centrations in media at the source.6.4.3 The time of initiation, duration, and rate of contami-nant release from the source.6.5 Identifying Migrati
43、on PathwaysPotential migrationpathways through ground water, surface water, air, soils,sediments, and biota should be identified for each source.Complete exposure pathways should be identified and distin-guished from incomplete pathways. An exposure pathway isincomplete if any of the following eleme
44、nts are missing: (1)amechanism of contaminant release from primary or secondarysources, (2) a transport medium if potential environmentalreceptors are not located at the source, and (3) a point ofpotential contact of environmental receptors with the contami-nated medium. The potential for both curre
45、nt and futurereleases and migration of the contaminants along the completepathways to the environmental receptors should be determined.A diagram (similar to that in Fig. X1.4) of exposure pathwaysfor all source types at a site should be constructed. Thisinformation should be consistent with the narr
46、ative portion andtables in the exposure assessment section of an exposure or riskassessment. Tracking contaminant migration from sources toenvironmental receptors is one of the most important uses ofthe conceptual site model.6.5.1 Ground Water PathwayThis pathway should beconsidered when hazardous s
47、olids or liquids have or may havecome into contact with the surface or subsurface soil or rock.The following should be considered further in that case:vertical distance to the saturated zone; subsurface flow rates;presence and proximity of downgradient seeps, springs, orcaves; fractures or other pre
48、ferred flow paths; artesian condi-tions; presence of wells, especially those for irrigation ordrinking water; and, in general, the underlying geology andhydrology of the site. Other fate and transport phenomena thatshould be considered include hydrodynamic dispersion, inter-phase transfers of contam
49、inants, and retardation. Movementthrough the vadose zone should be considered.6.5.2 Surface Water and Sediment PathwayThis pathwayshould always be investigated in the following situations: (1)aperennial body of water (river, lake, continuous stream, drain-age ditch, etc.) is in direct contact with, or is potentiallycontaminated by a source or contaminated area, (2) an unin-terrupted pathway exists from a source or contaminated area tothe surface water, (3) sampling and analysis of the surfacewater body or sediments indicate contaminant concentrationssubstantially abov
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