1、Designation:D766311 Designation: D7663 12Standard Practice forActive Soil Gas Sampling in the Vadose Zone for VaporIntrusion Evaluations1This standard is issued under the fixed designation D7663; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、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. Scope1.1 PurposeThis practice covers standardized techniques for actively collecting soil gas samples
3、from the vadose zonebeneath or near dwellings and other buildings.1.2 ObjectivesObjectives guiding the development of this practice are: (1) to synthesize and put in writing good commercialand customary practice for active soil gas sampling, (2) to provide an industry standard for soil gas sampling
4、performed in supportof vapor intrusion evaluations that is practical and reasonable.1.3 This practice allows a variety of techniques to be used for collecting soil gas samples because different techniques may offercertain advantages for specific applications. Three techniques are presented: sampling
5、 at discrete depths, sampling over a smallscreened interval, and sampling using permanent vapor monitoring wells.1.4 Some of the recommendations require knowledge of pressure differential and tracer gas concentration measurements.1.5 The values stated in SI units are toshall be regarded as standard.
6、 Other units are shown for information only.1.6 This practice does not address requirements of any federal, state, or local regulations or guidance, or both, with respect tosoil gas sampling. Users are cautioned that federal, state, and local guidance may impose specific requirements that differ fro
7、mthose of this practice.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior
8、to use.1.8 This practice offers a set of instructions for performing one or more specific operations. This document cannot replaceeducation or experience and should be used in conjunction with professional judgment. Not all aspects of this practice may beapplicable in all circumstances. This ASTM pr
9、actice is not intended to represent or replace the standard of care by which theadequacy of a given professional service must be judged, nor should this document be applied without consideration of a projectsmany unique aspects. The word “Standard” in the title means only that the document has been
10、approved through the ASTMconsensus process.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and Contained FluidsD854 Test Methods for Specific Gravity of Soil Solids by Water PycnometerD1356 Terminology Relating to Sampling and Analysis of AtmospheresD1946 Practice
11、 for Analysis of Reformed Gas by Gas ChromatographyD2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by MassD2487 Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)D3404 Guide for Measuring Matric Potential in
12、 Vadose Zone Using TensiometersD4696 Guide for Pore-Liquid Sampling from the Vadose ZoneD4700 Guide for Soil Sampling from the Vadose ZoneD5088 Practice for Decontamination of Field Equipment Used at Waste SitesD5092 Practice for Design and Installation of Ground Water Monitoring Wells1This practice
13、 is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.21 on Ground Water and VadoseZone Investigations.Current edition approved April 15, 2011. Published May 2011. DOI: 10.1520/D7663-11.on Groundwater and Vadose Zone Investigations.Cur
14、rent edition approved March 15, 2012. Published April 2012. Originally approved in 2011. Last previous edition approved in 2011 as D766311. DOI:10.1520/D7663-12.2For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of
15、ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technicall
16、y possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C7
17、00, West Conshohocken, PA 19428-2959, United States.D5314 Guide for Soil Gas Monitoring in the Vadose ZoneD5466 Test Method for Determination of Volatile Organic Chemicals in Atmospheres (Canister Sampling Methodology)D5504 Test Method for Determination of Sulfur Compounds in Natural Gas and Gaseous
18、 Fuels by Gas Chromatography andChemiluminescenceD6196 Practice for Selection of Sorbents, Sampling, and Thermal Desorption Analysis Procedures for Volatile OrganicCompounds in AirD6725 Practice for Direct Push Installation of Prepacked Screen Monitoring Wells in Unconsolidated AquifersE741 Test Met
19、hod for Determining Air Change in a Single Zone by Means of a Tracer Gas DilutionE2024 Test Methods for Atmospheric Leaks Using a Thermal Conductivity Leak DetectorF1815 Test Methods for Saturated Hydraulic Conductivity, Water Retention, Porosity, and Bulk Density of Athletic FieldRootzones3. Termin
20、ology3.1 This section provides definitions and descriptions of terms used in or related to this practice. A list of acronyms and a listof symbols also are included. The terms are an integral part of this practice and are critical to an understanding of the practice andits use.3.2 Definitions of Term
21、s Specific to This Standard:3.2.1 active sampling, na means of collecting a gas-phase substance that employs a mechanical device such as a pump orvacuum assisted critical orifice to draw air into or through a sampling device.3.2.2 adsorption, na physical process in which molecules or gas, of dissolv
22、ed substances, or of liquids adhere in an extremelythin layer to the surfaces of solid bodies with which they are in contact.3.2.3 ambient air, nany unconfined portion of the atmosphere; open air.3.2.4 attenuation factor (a), nratio of indoor air concentration to soil-gas concentration for a given c
23、ompound.3.2.5 background level, nthe concentration of a substance that is typically found in ambient air (for example, due to industrialor automobile emissions), indoor air (for example, from building materials or indoor activities) or the natural geology of an area.3.2.6 blank sample, na sample tha
24、t is intended to contain none of the analytes of interest and which is subjected to the usualanalytical or measurement process to establish a zero baseline or background value. Blank samples are named according to theirtype and use (for example, field blank, trip blank, equipment blank, reagent blan
25、k).3.2.7 contaminant, nsubstances not normally found in an environment at the observed concentration.3.2.8 dead volume, nthe total air-filled internal volume of the sampling system.3.2.9 duplicate samples, ntwo samples taken from and representative of the same population and carried through all step
26、s ofthe sampling and analytical procedures in an identical manner.3.2.10 effective porosity, nthe ratio of the volume of the voids of a soil or rock mass that can be drained by gravity to the totalvolume of the mass. the amount of interconnected void space (within intergranular pores, fractures, ope
27、nings, and the like)available for fluid movement: generally less than total porosity.3.2.11 equipment blank, na sample of the gas which is used to purge the sampling equipment between uses. Samplingequipment blanks are used to check the cleanliness of sampling devices and the thoroughness of the cle
28、aning procedure.3.2.12 field blank, nunused media carried to the sampling site, exposed to sampling conditions (for example, connected to thesampling lines) and returned to the laboratory and treated as an environmental sample. Field blanks are used to check for analyticalartifacts or background con
29、taminants or both introduced by sampling and analytical procedures.3.2.13 fracture, na break in the mechanical continuity of a body of rock or soil caused by stress exceeding the strength ofthe rock or soil. Includes joints and faults.3.2.14 free product, nliquid phase contaminants released into the
30、 environment. organic contaminants in the liquid (“free”or non-aqueous) phase.3.2.15 ground water, nthe part of the subsurface water that is in the saturated zone.3.2.16 liquid phase, ncontaminant residing as a liquid in vadose zone pore space, often referred to as “free product.”3.2.17 moisture con
31、tent, nthe amount of water lost from a soil upon drying to a constant weight, expressed as the weight perunit weight of dry soil or as the volume of water per unit bulk volume of the soil.3.2.18 passive sampling, na means of collecting an airborne substance that depends on gaseous diffusion, gravity
32、, or otherunassisted means to bring the sample to the collection surface of sorbent.3.2.19 partitioning, nthe act or process of distributing a chemical among different phases or compartments.3.2.20 perched aquifer, na lens of saturated soil above the main water table that forms on top of an isolated
33、 geologic layerof low permeability.3.2.21 permeability, nthe capacity of a rock or other material to conduct liquid or gas. It is measured as the proportionalityconstant, k, between flow velocity, v, and hydraulic gradient, I; v = kI. the ease with which a porous medium can transmit a fluidunder a p
34、otential gradient.3.2.22 preferential pathway, na migration route for chemicals of concern that has less constraint on gas transport than thesurrounding soil. Preferential pathways may be natural (for example, vertically fractured bedrock where the fractures areinterconnected) or man-made (for examp
35、le, utility conduits, sewers, dry wells).D7663 1223.2.23 porosity, nthe volume fraction of a rock or unconsolidated sediment not occupied by solid material but usuallyoccupied by liquids, vapor, or air, or combinations thereof. Porosity is the void volume of soil divided by the total volume of soil.
36、3.2.24 purge volume, nthe amount of air removed from the sampling system prior to the start of sample collection. This isusually referred to in number of dead volumes.3.2.25 reagent blank, nsample of one or more reagents used in a given analysis.3.2.26 saturated zone, nthe zone in which all of the v
37、oids in the rock or soil are filled with water at a pressure that is greaterthan atmospheric. The water table is the top of the saturated zone in an unconfined aquifer.3.2.27 semi-volatile organic compound (SVOC), norganic compounds with boiling points typically in the range 240-260 to380-400 C with
38、 polar compounds in the higher range.3.2.28 soil gas, nvadose zone atmosphere. Soil gas is the air existing in void spaces in the soil between the groundwater tableand the ground surface.3.2.29 soil moisture, nthe water contained in the pore spaces in the vadose zone.3.2.30 sorbent sampling, nthe co
39、llection of an air sample via removal of chemicals from a gas by passing the gas throughor allowing it to come in contact with a sorptive medium. The chemicals are subsequently desorbed for analysis.3.2.31 sub-slab vapor sampling, nthe collection of vapor from the zone just beneath the lowest floor
40、slab of a building.3.2.32 tracer, na material that can be easily identified and determined even at very low concentrations and that may be addedto other substances to enable their movements to be followed or their presence to be detected.3.2.33 tracer gas, na gas used with a detection device to dete
41、rmine the rate of air interchange within a space, or betweenspaces.3.2.34 trip blank, nclean, unused sampling media that is carried to the sampling site and transported to the laboratory foranalysis without having been exposed to sampling procedures.3.2.35 vadose zone, nhydrogeological region extend
42、ing from the soil surface to the top of the principal water table. Perchedground water may exist within this zone.3.2.36 vapor intrusion, nthe migration of a volatile chemical(s) from subsurface soil or water into an overlying or nearbybuilding.3.2.37 volatile organic compound (VOC), norganic compou
43、nds with boiling points typically ranging from a lower limitbetween 50 C and 100 C, and an upper limit between 240 C and 260 C, where the upper limits represent mostly polarcompounds.3.2.38 water table, nthe top of the saturated zone in an unconfined aquifer.3.3 Acronyms and Abbreviations3.3.1 BLSBe
44、low Land Surface (also known as below ground surface bgs)3.3.2 HDPEHigh density polyethylene tubing3.3.3 ODOuter Diameter3.3.4 PEEKPolyetheretherketone3.3.5 PTFEPolytetrafluoroethylene3.3.6 ppbvpart-per-billion on a volume basis3.3.7 PRTpost-run tubing3.3.8 QCQuality Control3.3.9 SVOCSemi-Volatile O
45、rganic Compound3.3.10 TOToxic Organic3.3.11 USEPAUnited States Environmental Protection Agency3.3.12 VOCVolatile Organic Compound3.4 Symbols3.4.1 Variables (typical units)3.4.1.1 C = concentration (ppbv, g/m3,%)3.4.1.2 CDL= detection limit concentration (g/m3)3.4.1.3 d = diameter (cm)3.4.1.4 L = len
46、gth (cm)3.4.1.5 M = mass (g)3.4.1.6 n = number of data points3.4.1.7 Q = flow rate (cm3/min)3.4.1.8 t = time (min)3.4.1.9 V = volume (cm3)3.4.1.10 XMW= molecular weight of compound X (g/mol)3.4.1.11 a = attenuation coefficient or factor (dimensionless)3.4.1.12 DP = change in pressure (Pa)3.4.1.13 t
47、= residence time (min)3.5 SuperscriptsD7663 1233.5.1 = mean value3.6 Subscripts3.6.1 i = pertaining to compound, time, or location i4. Summary of Practice4.1 This practice describes the active collection of soil gas samples from soil pore spaces in the vadose zone or in fill materialdirectly under b
48、uilding slabs to determine the concentration of volatile organic compounds (VOCs). Three techniques arepresented: (1) sampling at discrete depths, (2) sampling over a small screened interval, or (3) sampling using permanent vapormonitoring wells with one or more screened intervals. For sampling at a
49、 given depth, options include (i) a short stainless steel probeinstalled in a small diameter hole drilled through building slab, (ii) disposable drive tips and post-run tubing (PRT), or (iii)installation of sampling points using tubing placed into a borehole and sealed in place with clay or other packing material. Severaldifferent combinations of equipment and materials can be used to actively collect soil gas samples, and this practice is intendedto allow all methods that typically result in representative and re
