1、Designation: E2856 111Standard Guide forEstimation of LNAPL Transmissivity1This standard is issued under the fixed designation E2856; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenthese
2、s indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial changes were made throughout in January 2012.1. Scope1.1 This guide provides field data collection and calculationmethodologies for the estimation of li
3、ght non-aqueous phaseliquid (LNAPL) transmissivity in unconsolidated porous sedi-ments. The methodologies presented herein may, or may notbe, applicable to other hydrogeologic regimes (for example,karst, fracture flow). LNAPL transmissivity represents thevolume of LNAPL (L3) through a unit width (L)
4、 of aquifer perunit time (t) per unit drawdown (L) with units of (L2/T).LNAPL transmissivity is a directly proportional metric forLNAPL recoverability whereas other metrics such as apparentLNAPL thickness gauged in wells do not exhibit a consistentrelationship to recoverability. The recoverability f
5、or a givengauged LNAPL thickness in a well will vary between differentsoil types, LNAPL types or hydrogeologic conditions. LNAPLtransmissivity accounts for those parameters and conditions.LNAPL transmissivity values can be used in the following fiveways: (1) Estimate LNAPL recovery rate for multiple
6、 tech-nologies; (2) Identify trends in recoverability via mapping; (3)Applied as a leading (startup) indicator for recovery; (4)Applied as a lagging (shutdown) indicator for LNAPL recov-ery; and (5) Applied as a robust calibration metric for multi-phase models (Hawthorne and Kirkman, 2011 (1)2and IT
7、RC(2). The methodologies for LNAPL transmissivity estimationprovided in this document include short-term aquifer testingmethods (LNAPL baildown/slug testing and manual LNAPLskimming testing), and long-term methods (that is, LNAPLrecovery system performance analysis, and LNAPL tracertesting). The mag
8、nitude of transmissivity of any fluid in thesubsurface is controlled by the same variables (that is, fluidpore space saturation, soil permeability, fluid density, fluidviscosity, the interval that LNAPL flows over in the formationand the gravitational acceleration constant). A direct math-ematical r
9、elationship exists between the transmissivity of afluid and the discharge of that fluid for a given induceddrawdown. The methodologies are generally aimed at measur-ing the relationship of discharge versus drawdown for theoccurrence of LNAPL in a well, which can be used to estimatethe transmissivity
10、 of LNAPL in the formation. The focus,therefore, is to provide standard methodology on how to obtainaccurate measurements of these two parameters (that is,discharge and drawdown) for multi-phase occurrences toestimate LNAPL transmissivity.1.2 Organization of this Guide:1.2.1 Section 2 presents docum
11、ents referenced.1.2.2 Section 3 presents terminology used.1.2.3 Section 4 presents significance and use.1.2.4 Section 5 presents general information on four meth-ods for data collection related to LNAPL transmissivity calcu-lation. This section compares and contrasts the methods in away that will al
12、low a user of this guide to assess which methodmost closely aligns with the site conditions and available datacollection opportunities.1.2.5 Sections 6 and 7 presents the test methods for each ofthe four data collection options. After reviewing Section 5 andselecting a test method, a user of this gu
13、ide shall then proceedto the applicable portion of Sections 6 and 7 which describesthe detailed test methodology for the selected method.1.2.6 Section 8 presents data evaluation methods. Afterreviewing Section 5 and the pertinent test method section(s) ofSections 6 and 7, the user of this guide shal
14、l then proceed to theapplicable portion(s) of Section 8 to understand the method-ologies for evaluation of the data which will be collected. It ishighly recommended that the test methods and data evaluationprocedures be understood prior to initiating data collection.1.3 The values stated in inch-pou
15、nd units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theres
16、ponsibility 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.1This guide is under the jurisdiction ofASTM Committee E50 on EnvironmentalAssessment, Risk Management and Corrective Action and is t
17、he direct responsibil-ity of Subcommittee E50.04 on Corrective Action.Current edition approved Nov. 1, 2011. Published January 2012. DOI: 10.1520/E285611.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.1Copyright ASTM International, 100 Barr Harbor Dri
18、ve, PO Box C700, West Conshohocken, PA 19428-2959, United States.1.5 This document is applicable to wells exhibiting LNAPLconsistently (that is, LNAPL transmissivity values above zero).This methodology does not substantiate zero LNAPL transmis-sivity; rather the lack of detection of LNAPL within the
19、 wellcombined with proper well development and purging proce-dures are required to confirm zero LNAPL transmissivity.1.6 This document cannot replace education or experienceand should be used in conjunction with professional compe-tence in the hydrogeology field and expertise in the behavior ofLNAPL
20、 in the subsurface.1.7 This document cannot be assumed to be a substitute foror replace any laws or regulations whether federal, state, tribalor local.2. Referenced Documents2.1 ASTM Standards:3D653 Terminology Relating to Soil, Rock, and ContainedFluidsD5088 Practice for Decontamination of Field Eq
21、uipmentUsed at Waste SitesD5521 Guide for Development of Ground-Water Monitor-ing Wells in Granular AquifersE2531 Guide for Development of Conceptual Site Modelsand Remediation Strategies for Light Nonaqueous-PhaseLiquids Released to the Subsurface3. Terminology3.1 Definitions:3.1.1 air/LNAPL interf
22、ace (Zan)The surface shared by airand LNAPL in a control well. (L)3.1.2 calculated water-table elevation (ZCGW)the theo-retical location of the air/water surface based on a densitycorrection if LNAPL were not present in a well. (L)3.1.3 confined LNAPLLNAPL trapped in an aquifer be-neath a layer that
23、 exhibits a pore entry pressure greater than thecapillary LNAPL head, thereby impeding the upward migra-tion of LNAPL limits the upward movement of the LNAPL.The term confined LNAPL is used because the mobile LNAPLis under pressure greater than gauge pressure against theunderside of the LNAPL confin
24、ing layer.3.1.4 control wellwell by which the aquifer is stressed ortested.3.1.5 dischargethe flow of a fluid into or out of a well.(L3/t)3.1.6 drawdowna pressure differential in terms of fluidhead. (L)3.1.7 effective well radiusthe radius that represents thearea of the well casing and the interconn
25、ected porosity of thefilter pack. (L)3.1.8 equilibrium fluid levelsgauged fluid levels that rep-resent the oil head and the water head or the calculatedwater-table elevation of the formation. Under equilibrium fluidlevels no net oil or water flow occurs between the formationand the well.3.1.9 fluid
26、levelthe level of a fluid interface (either air/oil,LNAPL/water, or potentiometric surface).3.1.10 formation thickness (bnf)the interval that LNAPLflows over in the formation. For unconfined conditions this isapproximately equal to the gauged LNAPLthickness. Confinedand perched conditions the gauged
27、 LNAPL thickness underequilibrium conditions is not equal to the formation thickness.(L)3.1.11 gauged LNAPL thickness (bn)The difference be-tween the gauged air/LNAPL interface and the water/LNAPLinterface in a well. (L)3.1.12 hydraulic conductivity (derived via field aquifertests)the volume of wate
28、r at the existing kinematic viscositythat will move in a unit time, under a unit hydraulic gradient,through a unit area, measured at right angles to the direction offlow. (L/t)3.1.13 LNAPLLight Non Aqueous Phase Liquid.3.1.14 LNAPL baildown testa procedure which includesthe act of removing a measure
29、d LNAPL volume from a welland filter pack to induce a head differential and the follow-upgauging of fluid levels in the well.3.1.15 LNAPL borehole volumethe volume of LNAPLexisting within the casing and the drainable volume existingwithin the filter pack of a well. Based on effective radius andgauge
30、d thickness of LNAPL. (L3)3.1.16 LNAPL slug testa procedure which includes the actof removing or displacing a known volume of LNAPL from awell to induce a head differential and the follow-up gauging offluid levels in the well.3.1.17 LNAPL specific yield (Syn)the volume of LNAPLan aquifer releases or
31、 takes into storage per unit surface area ofthe aquifer per unit change in LNAPL head for gravitydrainage conditions. (unitless)3.1.18 LNAPL specific yield filter pack (Syf)the volume ofLNAPL released or takes into storage per unit surface area ofthe filter pack per unit change in LNAPL head for gra
32、vitydrainage conditions. (unitless)3.1.19 LNAPL storage coeffcient (Sn)the volume ofLNAPL an aquifer releases from or takes into storage per unitsurface area of the aquifer per unit change in LNAPL head. Fora confined aquifer, it is based on the volume of fluid releaseddue to decompression. For an u
33、nconfined aquifer, the storagecoefficient is approximately equal to the LNAPL specific yield.(unitless)3.1.20 LNAPL transmissivity (Tn)the volume of LNAPLat the existing kinematic viscosity that will move in a unit timeunder a unit hydraulic gradient through a unit width of theaquifer. (L2/t)3.1.21
34、observation wella well screened across all or partof an aquifer.3.1.22 oil/water interface (Znw)The surface shared byLNAPL and water in a control well. (L)3.1.23 perched LNAPLmobile LNAPL that accumulatesin the vadose zone of a site for some time period above a layerthat exhibits a pore entry pressu
35、re greater than the capillaryLNAPL head, thereby impeding the downward migration ofLNAPL.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summ
36、ary page onthe ASTM website.E2856 11123.1.24 potentiometric surfacesee calculated water-tableelevation.3.1.25 radius of influencethe distance from a well that thepumping induced head differential from non-pumping condi-tions is zero, head differentials due to background gradientsmay still exist at t
37、his radius. (L)3.1.26 sluga volume of water or solid object used toinduce a sudden change of head in a well.3.1.27 test wella well by which the aquifer is stressed, forexample, by pumping, injection, or change of head.3.2 For definitions of other terms used in this test methodrefer to Terminology, G
38、uide D653.4. Significance and Use4.1 Application:4.1.1 LNAPL transmissivity is an accurate metric for un-derstanding LNAPL recovery, is directly proportional toLNAPL recoverability and tracking remediation progress to-wards residual LNAPL saturation.4.1.2 LNAPL transmissivity can be used to estimate
39、 the rateof recovery for a given drawdown from various technologies.4.1.3 LNAPL transmissivity is not an intrinsic aquiferproperty but rather a summary metric based on the aquiferproperties, LNAPL physical properties, and the magnitude ofLNAPL saturation over a given interval of aquifer.4.1.4 LNAPLt
40、ransmissivity will vary over time with chang-ing conditions such as, seasonal fluctuations in water table,changing hydrogeologic conditions and with variability inLNAPL impacts (that is, interval that LNAPL flows over in theformation and LNAPL pore space saturation) within theformation.4.1.5 Any obs
41、erved temporal or spatial variability in valuesderived from consistent data collection and analysis methods ofLNAPL transmissivity is not erroneous rather is indicative ofthe actual variability in subsurface conditions related to theparameters encompassed by LNAPL transmissivity (that is,fluid pore
42、space saturation, soil permeability, fluid density,fluid viscosity, and the interval that LNAPL flows over in theformation).4.1.6 LNAPL transmissivity is a more accurate metric forevaluating recoverability and mobile LNAPL than gaugedLNAPL thickness. Gauged LNAPL thickness does not accountfor soil p
43、ermeability, magnitude of LNAPL saturation aboveresidual saturation, or physical fluid properties of LNAPL (thatis, density, interfacial tension, and viscosity).4.1.7 The accurate calculation of LNAPL transmissivityrequires certain aspects of the LNAPL Conceptual Site Model(LSCM) to be completely un
44、derstood and defined in order tocalculate LNAPL drawdown correctly. The methodologies fordevelopment of the LSCM are provided in Guide E2531. Thegeneral conceptual site model aspects applicable to this guideinclude:4.1.7.1 Equilibrium fluid levels (for example, air/LNAPLand LNAPL/water).4.1.7.2 Soil
45、 profile over which LNAPL is mobile.4.1.7.3 LNAPL hydrogeologic scenario (for example, un-confined, confined, perched, macro pores, and so forth).4.1.7.4 LNAPL density.4.1.7.5 Hydraulic conductivity for each soil type within thewell screen interval.4.1.7.6 Well screen interval in the vadose and satu
46、ratedzones.4.1.8 Incorporation of LNAPL transmissivity can furtherLSCMs by providing a single comparable metric that quantifiesLNAPL recoverability at individual locations across a site.4.1.9 Each of the methods provided in this document isapplicable to LNAPL in confined, unconfined, and perchedcond
47、itions. Any differences in evaluation are discussed inSection 5.4.2 PurposeThe methods used to calculate LNAPL trans-missivity have been published over the past 20 years; howeverlittle effort has been focused on providing quality assurance forindividual tests or refinement of field procedures. In ad
48、dition tosummarizing the existing methods to calculate LNAPL trans-missivity, this document will provide guidance on refined fieldprocedures for data collection and minimum requirements fordata sets before they are used to calculate LNAPL transmis-sivity.4.2.1 ConsiderationsThe following section pro
49、vides abrief review of considerations associated with LNAPL trans-missivity testing.4.2.1.1 Aquifer Conditions (confined, unconfined,perched)In general, each testing type is applicable to con-fined, unconfined, and perched conditions; however, consider-ation should be given to how LNAPL drawdown is calculatedfrom well gauging data relative to formation conditions.Calculation of LNAPL transmissivity for confined and perchedconditions is possible; however, the soil profile needs to beconsidered in combination with the fluid levels to accuratelycalcu
