1、Designation: D7758 17Standard Practice forPassive Soil Gas Sampling in the Vadose Zone for SourceIdentification, Spatial Variability Assessment, Monitoring,and Vapor Intrusion Evaluations1This standard is issued under the fixed designation D7758; the number immediately following the designation indi
2、cates the year oforiginal adoption or, in the case of revision, the year of 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. Scope*1.1 PurposeThis practice covers standardized
3、techniquesfor passively collecting soil gas samples from the vadose zoneand is to be used in conjunction with Guide D5314.1.2 ObjectivesObjectives guiding the development of thispractice are: (1) to synthesize and put in writing good com-mercial and customary practice for conducting passive soil gas
4、sampling, (2) to ensure that the process for collecting andanalyzing passive soil gas samples is practical and reasonable,and (3) to provide standard guidance for passive soil gassampling performed in support of source identification, spatialvariability/extent determinations, site assessment, sitemo
5、nitoring, and vapor intrusion investigations.1.3 This practice does not address requirements of anyfederal, state, or local regulations or guidance or both withrespect to soil gas sampling. Users are cautioned that federal,state, and local guidance may impose specific requirementsthat differ from th
6、ose of this practice.1.4 UnitsThe values stated in SI units are to be regardedas standard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this
7、standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This practice offers a set of instructions for performingone or more specific operations. This document cannot replaceeducation or experience and
8、 should be used in conjunctionwith professional judgment. Not all aspects of this practice maybe applicable in all circumstances. This ASTM standard is notintended to represent or replace the standard of care by whichthe adequacy of a given professional service must be judged,nor should this documen
9、t be applied without consideration ofa projects many unique aspects. The word “Standard” in thetitle means only that the document has been approved throughthe ASTM consensus process.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-iz
10、ation established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and Contain
11、edFluidsD1356 Terminology Relating to Sampling and Analysis ofAtmospheresD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and Rock by MassD2487 Practice for Classification of Soils for EngineeringPurposes (Unified Soil Classification System)D3740 Practice for Minimu
12、m Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4597 Practice for Sampling Workplace Atmospheres toCollect Gases or Vapors with Solid Sorbent DiffusiveSamplersD5088 Practice for Decontamination of Field EquipmentUsed at W
13、aste SitesD5314 Guide for Soil Gas Monitoring in the Vadose Zone(Withdrawn 2015)3D5792 Practice for Generation of Environmental Data Re-lated to Waste Management Activities: Development ofData Quality Objectives1This practice is under the jurisdiction of ASTM Committee D18 on Soil andRock and is the
14、 direct responsibility of Subcommittee D18.21 on Groundwater andVadose Zone Investigations.Current edition approved June 1, 2017. Published July 2017. Originally approvedin 2011. Last previous edition approved in 2016 as D775811(2016). DOI:10.1520/D7758-17.2For referenced ASTM standards, visit the A
15、STM 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.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Change
16、s section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decis
17、ion on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1D6196 Practice for Choosing Sorbents, Sampling Param-eters and Thermal Desorption Analytical Conditions forMonitoring Volati
18、le Organic Chemicals in AirD6311 Guide for Generation of Environmental Data Relatedto Waste Management Activities: Selection and Optimiza-tion of Sampling DesignE2600 Guide for Vapor Encroachment Screening on Prop-erty Involved in Real Estate Transactions2.2 U.S. EPA Methods4Method 8260C Volatile Or
19、ganic Compounds by GasChromatography/Mass Spectrometry (GC/MS)Method 8270C Semivolatile Organic Compounds by GasChromatography/Mass SpectrometryMethod TO-17 Determination of Volatile Organic Com-pounds in Ambient Air Using Active Sampling OntoSorbent Tubes3. Terminology3.1 Definitions:3.1.1 For comm
20、on definitions of terms in this standard, referto Terminology D653 and D1356.3.2 Definitions of Terms Specific to This Standard:3.2.1 absorption, nthe penetration of one substance intothe inner structure of another.3.2.2 adsorption, nadherence of the atoms, ions, or mol-ecules of a gas or liquid to
21、the surface of another substance(chemisorption).3.2.3 ambient air, nany unconfined portion of the atmo-sphere; open air.3.2.4 blank sample, nclean sample or a sample of matrixprocessed to measure artifacts in the measurement process.3.2.4.1 DiscussionBlank samples are named according totheir type an
22、d use (for example, method blank, trip blank, fieldblank, and preparation or manufacturing blank).3.2.5 desorption, nthe process of freeing from a sorbedstate.3.2.6 duplicate samples, ntwo samples taken from andrepresentative of the same population that are carried throughall steps of the sampling a
23、nd analytical procedures in anidentical manner.3.2.7 field blank, nclean sampling media that is carried tothe sampling site, exposed to ambient air during field samplingprocedures, and transported to the laboratory for analysis (alsoreferred to as an ambient air control sample).3.2.8 method blank, n
24、quality control check to measurelaboratory contamination during sample analysis.3.2.9 moisture content, nthe moisture present in amaterial, as determined by definite prescribed methods, ex-pressed as a percentage of the mass of the sample on either ofthe following bases: (1) original mass ; (2) mois
25、ture-free (ovendried) mass (see Test Method D2216).3.2.10 preparation blank, nquality control check to definethe efficiency of conditioning a batch of sorbent samplers at thelaboratory for sample collection (also referred to as manufac-turing blanks).3.2.11 sampling rate, nthe ratio of mass of a giv
26、encompound collected by a diffusive sampler per unit time ofexposure to the concentration of that compound in the atmo-sphere being sampled. The sampling rate is sometimes referredto as the uptake rate.3.2.12 soil gas, nvadose zone atmosphere; soil gas is theair existing in void spaces in the soil b
27、etween the groundwatertable and the ground surface.3.2.13 soil moisture, nwater contained in the pore spacesin the vadose zone.3.2.14 sorbent, na solid or liquid medium in or uponwhich materials are collected by adsorption, absorption, orchemisorption.3.2.15 sorbent sampling, vthe collection of chem
28、icalsfrom an air or emission sample by allowing the air or emissionsto contact a sorbent.3.2.16 source, narea(s) at a site where releases haveoccurred that are emanating vapors from either the vadose zoneor groundwater.3.2.16.1 DiscussionThere may be multiple sources at asite and the area over which
29、 any one source is defined is subjectto interpretation from multiple data sets.3.2.17 spatial variability, nrelationship of organic com-pound mass from one location to many others at a site as afunction of distance.3.2.18 starvation effect, nwhen the analyte uptake rate ofa passive sorbent sampler i
30、s greater than the replenishment rateof the analyte around the sampler, which results in a low biasmeasurement.3.2.19 trip blank, nclean, unused sampling media that iscarried to the sampling site and transported to the laboratoryfor analysis without having been exposed to field samplingprocedures.3.
31、2.20 vapor intrusion, nmigration of a volatile chemi-cal(s) from subsurface soil or water into an overlying or nearbybuilding.3.3 Acronyms:3.3.1 BLSBelow land surface (also know as below groundsurface (bgs)3.3.2 QA/QCQuality assurance and quality control3.3.3 PSGPassive soil gas3.3.4 SVOCSemivolatil
32、e organic compound3.3.5 VOCVolatile organic compound4. Summary of Practice4.1 This practice describes the passive collection and sub-sequent analysis of soil gas samples, using sorbent samplers totrap VOCs and SVOCs in soil vapor by placing samplers in thesubsurface for a period of time at multiple
33、locations across asite. Placement of the sampler can be in open soils (that is, not4Available from United States Environmental Protection Agency (EPA), ArielRios Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20004, http:/www.epa.gov.D7758 172covered by a surface such as asphalt or concrete), or
34、advancedthrough slab surfaces (for example, parking lots, streets,sidewalks, building slabs, and basement floors) to allow forsubslab soil gas sampling. This practice provides standardguidance for passive soil gas (PSG) sampling and analysisperformed in support of, but not limited to, site assessmen
35、t, sitemonitoring, and vapor intrusion investigations. While severaldifferent types and combinations of sorbent materials can beused to trap VOCs and SVOCs in soil gas, this practice isintended to achieve representative and reproducible samples ofknown quality. The design of PSG surveys (for example
36、,sampler design, sample spacing, the sampler exposure period,and analytical methods) is within the scope of this practice.These guidelines are not intended to restrict the sampler designor its application in regards to spacing, sampler distribution, ortime of exposure; however, these guidelines are
37、meant toprovide a general idea of common practice at the time thisstandard was prepared.5. Significance and Use5.1 Passive soil gas samplers are a minimally invasive,easy-to-use technique in the field for identifying VOCs andSVOCs in the vadose zone. Similar to active soil gas and otherfield screeni
38、ng techniques, the simplicity and low cost ofpassive samplers enables them to be applied in large numbers,facilitating detailed mapping of contamination across a site, forthe purpose of identifying source areas and release locations,focusing subsequent soil and groundwater sampling locations,focusin
39、g remediation plans, identifying vapor intrusionpathways, tracking groundwater plumes, and monitoring reme-diation progress. Data generated from passive soil gas sam-pling are semi-quantitative and are dependent on numerousfactors both within and outside the control of the samplingpersonnel. Key var
40、iables are identified and briefly discussed inthe following sections.NOTE 1Additional non-mandatory information on these factors orvariables are covered in the applicable standards referenced in Section 2,and the footnotes and Bibliography presented herewith.5.2 ApplicationThe techniques described i
41、n this practiceare suitable for sampling soil gas with sorbent samplers in awide variety of geological settings for subsequent analysis forVOCs and SVOCs. The techniques also may prove useful forspecies other than VOCs and SVOCs, such as elementalmercury, with specialized sorbent media and analysis.
42、5.2.1 Source Identification and Spatial VariabilityAssessmentPassive soil gas sampling can be an effectivemethod to identify contaminant source areas in the vadose zoneand delineate the extent of contamination. By collectingsamples in a grid with fewer data gaps, the method allows foran increase in
43、data density and, therefore, provides a high-resolution depiction of the nature and extent of contaminationacross the survey area. By comparing the results, as qualitativeor quantitative, from one location to another, the relativedistribution and spatial variability of the contaminants in thesubsurf
44、ace can be determined, thereby improving the concep-tual site model. Areas of the site reporting non-detects can beremoved from further investigation, while subsequent sam-pling and remediation can be focused in areas determined fromthe PSG survey to be impacted.5.2.2 MonitoringPassive soil gas samp
45、lers are used tomonitor changes in site conditions (for example, new releaseson-site, an increase in contaminant concentrations in ground-water from onsite or off-site sources, and effectiveness ofremedial system performance) as reflected by the changes insoil gas results at fixed locations over tim
46、e. An initial set ofdata is collected to establish a baseline and subsequent data setsare collected for comparison. The sampling and analyticalprocedures should remain as near to constant as possible sosignificant changes in soil gas results can be attributed to thosechanges in subsurface contaminan
47、t levels at the site that willthen warrant further investigation to identify the cause.5.2.3 Vapor Intrusion EvaluationPassive soil gas sam-pling can be used to identify vapor migration and intrusionpathways (see Practice E2600), with the data providing a lineof evidence on the presence or absence o
48、f the compounds insoil vapor, the nature and extent in relation to potentialreceptors, and whether a vapor pathway is complete. Sorbentsamplers can be placed beneath the slab or in close proximityto buildings to collect time-integrated samples targeting VOCsand SVOCs at concentrations often lower th
49、an can be achievedwith active soil gas sampling methods.5.3 LimitationsPassive soil gas data are reported in massof individual compounds or compound groups identified persample location, with the reporting units generally in nano-grams (ng) or micrograms (g) per sampler and not a concen-tration (see 6.8). Ideally, the data produced using this methodwill be representative of time-weighted soil gas concentrations,present in the vicinity of the PSG sampler and sorbed on thesampler during the exposure period; however, non-uniformityof sampler desig
