1、Designation: E1689 95 (Reapproved 2014)Standard Guide forDeveloping Conceptual Site Models for Contaminated Sites1This standard is issued under the fixed designation E1689; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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)integr
3、ation 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-nat
4、ed 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-tami
5、nated 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 a
6、ddress 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:2D2216 Test
7、Methods for Laboratory Determination of Water(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,April 1992Guidance for Data Useability in Risk Assessment (Part B),OSWER Directive 9285.7-09B
8、, 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(s) o
9、r 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 repre
10、sentation 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 is po
11、tentially 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 dust
12、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 agent i
13、n 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.3.1.7 exposure route, nthe process by which a contami-nant or physical agent in the environment comes into directconta
14、ct with the body, tissues, or exchange boundaries of anenvironmental receptor organism, for example, ingestion,inhalation, dermal absorption, root uptake, and gill uptake.1This guide is under the jurisdiction ofASTM Committee E50 on EnvironmentalAssessment, Risk Management and Corrective Action and
15、is the direct responsibil-ity of Subcommittee E50.05 on Environmental Risk Management.Current edition approved Jan. 1, 2014. Published May 2014. Originally approvedin 1995. Last previous edition approved in 2008 as E168995(2008). DOI:10.1520/E1689-95R14.2For referenced ASTM standards, visit the ASTM
16、 website, 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, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadel
17、phia, PA 19111-5098, http:/dodssp.daps.dla.mil.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.8 migration pathway, nthe course through which con-taminants in the environment may move away from thesource(s) to potential environmen
18、tal receptors.3.1.9 source, nthe location 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. S
19、ummary of Guide4.1 The six basic activities 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 contaminant
20、s; (3) delineation ofpotential migration pathways 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 re
21、ceptors (human and eco-logical); and (6) determination 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 d
22、evelopment should start as early in the siteinvestigation 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 e
23、xposure scenarios.4.3 The concerns of ecological 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 representati
24、ons of the con-ceptual site model in the human 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 in
25、formation gained through the site investigation 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 co
26、nceptual site model.5.2 Development of this 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 b
27、e identified clearly sothat efforts can be 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 t
28、o integrate all siteinformation and to determine 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 reme
29、dial actions in reduc-ing the exposure of 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 an
30、d promote a uniformapproach to developing 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, r
31、emedialinvestigation, baseline human health and ecological riskassessments, 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.
32、5.6 The steps in the procedure for developing 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 his
33、torical and cur-rent site-related information 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
34、should beevaluated, preferably including 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 Assess
35、ment(Part A)and Guidance for Data Useability 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 anothe
36、r such that itis not possible to determine 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
37、, and air. Ifno contaminants are found, 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 analyteE1689 95 (2014)2attributab
38、le to natural occurrence at the site; (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
39、the naturallyoccurring concentrations 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 con
40、tami-nation attributable to the source(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 thedevelopm
41、ent of a conceptual site model.6.4 Characterizing 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 indicat
42、or (for example,north arrow). They should 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 f
43、rom the source.6.5 Identifying Migration 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 isin
44、complete if any of the following elements 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-nate
45、d medium. The potential for both current 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. Thisinformat
46、ion should be consistent with the narrative 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 pathwa
47、y should beconsidered when hazardous solids 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, sp
48、rings, orcaves; fractures or other preferred 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 dispe
49、rsion, inter-phase transfers of contaminants, 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 cont
