ASTM E2856-2011 Standard Guide for Estimation of LNAPL Transmissivity.pdf

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1、Designation: E2856 11Standard 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 parentheses

2、 indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide provides field data collection and calculationmethodologies for the estimation of light non-aqueous phaseliquid (LNAPL) transmissivity in unconso

3、lidated 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) of aquifer perunit time (t) per unit drawdown (L) with units

4、 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 for a givengauged LNAPL thickness in a well will vary between

5、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 tech-nologies; (2) Identify trends in recoverability via map

6、ping; (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 ITRC(2). The methodologies for LNAPL transmissivity estimationp

7、rovided 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 magnitude of transmissivity of any fluid in thesubsurface is con

8、trolled 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 relationship exists between the transmissivity of afluid and t

9、he 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 of LNAPL in the formation. The focus,therefore, is to provid

10、e 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 documents referenced.1.2.2 Section 3 presents terminology used.1.2

11、.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 allow a user of this guide to assess which methodmost closely a

12、ligns 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 guide shall then proceedto the applicable portion of Sections 6

13、 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 shall then proceed to theapplicable portion(s) of Section 8 to un

14、derstand 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-pound units are to be regardedas standard. The values given in p

15、arentheses 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 theresponsibility of the user of this standard to establish appro-p

16、riate safety and health practices and determine the applica-bility of regulatory limitations prior to use.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

17、the lack of detection of LNAPL within the well1This guide is under the jurisdiction ofASTM Committee E50 on EnvironmentalAssessment, Risk Management and Corrective Action and is the direct responsibil-ity of Subcommittee E50.04 on Corrective Action.Current edition approved Nov. 1, 2011. Published Ja

18、nuary 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 Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Sbined with proper well development and purging proce-dures are

19、 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 in the subsurface.1.7 This document cannot be assumed to be a substit

20、ute 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 EquipmentUsed at Waste SitesD5521 Guide for Development of Ground-Water

21、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 interface (Zan)The surface shared by airand LNAPL in a control well. (L)3.1.

22、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 exhibits a pore entry pressure greater than thecapillary LNAPL head,

23、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 confining layer.3.1.4 dischargethe flow of a fluid into or out of a well.(L3

24、/t)3.1.5 drawdowna pressure differential in terms of fluidhead. (L)3.1.6 fluid levelthe level of a fluid interface (either air/oil,LNAPL/water, or potentiometric surface).3.1.7 formation thickness (bnf)the interval that LNAPLflows over in the formation. For unconfined conditions this isapproximately

25、 equal to the gauged LNAPLthickness. Confinedand perched conditions the gauged LNAPL thickness underequilibrium conditions is not equal to the formation thickness.(L)3.1.8 gauged LNAPL thickness (bn)The difference be-tween the gauged air/LNAPL interface and the water/LNAPLinterface in a well. (L)3.1

26、.9 hydraulic conductivity (derived via field aquifertests)the volume of water 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)3.1.10 LNAPLLight Non Aqueous Phase Liquid.3.1.1

27、1 LNAPL baildown testa procedure which includesthe act of removing a measured LNAPL volume from a welland filter pack to induce a head differential and the follow-upgauging of fluid levels in the well.3.1.12 LNAPL borehole volumethe volume of LNAPLexisting within the casing and the drainable volume

28、existingwithin the filter pack of a well. Based on effective radius andgauged thickness of LNAPL. (L3)3.1.13 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 wel

29、l.3.1.14 LNAPL specific yield (Syn)the volume of LNAPLan aquifer releases or takes into storage per unit surface area ofthe aquifer per unit change in LNAPL head for gravitydrainage conditions. (unitless)3.1.15 LNAPL specific yield filter pack (Syf)the volume ofLNAPL released or takes into storage p

30、er unit surface area ofthe filter pack per unit change in LNAPL head for gravitydrainage conditions. (unitless)3.1.16 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 aquife

31、r, it is based on the volume of fluid releaseddue to decompression. For an unconfined aquifer, the storagecoefficient is approximately equal to the LNAPL specific yield.(unitless)3.1.17 LNAPL transmissivity (Tn)the volume of LNAPLat the existing kinematic viscosity that will move in a unit timeunder

32、 a unit hydraulic gradient through a unit width of theaquifer. (L2/t)3.1.18 observation wella well screened across all or partof an aquifer.3.1.19 oil/water interface (Znw)The surface shared byLNAPL and water in a control well. (L)3.1.20 perched LNAPLmobile LNAPL that accumulatesin the vadose zone o

33、f a site for some time period above a layerthat exhibits a pore entry pressure greater than the capillaryLNAPL head, thereby impeding the downward migration ofLNAPL.3.1.21 potentiometric surfacesee calculated water-tableelevation.3.1.22 radius of influencethe distance from a well that thepumping ind

34、uced head differential from non-pumping condi-tions is zero, head differentials due to background gradientsmay still exist at this radius. (L)3.1.23 sluga volume of water or solid object used toinduce a sudden change of head in a well.3.1.24 test wella well by which the aquifer is stressed, forexamp

35、le, by pumping, injection, or change of head.3.2 For definitions of other terms used in this test methodrefer to Terminology, Guide D653.4. Significance and Use4.1 Application:3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. Fo

36、r Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.E2856 1124.1.1 LNAPL transmissivity is an accurate metric for un-derstanding LNAPL recovery, is directly proportional toLNAPL recoverability and tracking remediation progress to-wards r

37、esidual LNAPL saturation.4.1.2 LNAPL transmissivity can be used to estimate 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

38、 magnitude ofLNAPL saturation over a given interval of aquifer.4.1.4 LNAPLtransmissivity 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 thef

39、ormation and LNAPL pore space saturation) within theformation.4.1.5 Any observed 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 relate

40、d to theparameters encompassed by LNAPL transmissivity (that is,fluid pore 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 th

41、an gaugedLNAPL thickness. Gauged LNAPL thickness does not accountfor soil permeability, 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 c

42、ertain aspects of the LNAPL Conceptual Site Model(LSCM) to be completely understood 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 Eq

43、uilibrium fluid levels (for example, air/LNAPLand LNAPL/water).4.1.7.2 Soil 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

44、thewell screen interval.4.1.7.6 Well screen interval in the vadose and saturatedzones.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 t

45、his document isapplicable to LNAPL in confined, unconfined, and perchedconditions. 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 qua

46、lity assurance forindividual tests or refinement of field procedures. In addition 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 ca

47、lculate LNAPL transmis-sivity.4.2.1 ConsiderationsThe following section provides 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 co

48、nditions; 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 flu

49、id levels to accuratelycalculate drawdown. Drawdown values for perched and con-fined conditions can easily be overestimated without properconsideration. This results in LNAPL transmissivity beingunderestimated. The calculations of drawdown under perchedand confined conditions are discussed within this document.Tidal influences or a vertical gradient on the water table alsoaffect measurements and could distort the transmissivity re-sults. Tidal influences are discussed in more detail inAppendixX1.4.2.1.2 Well ConstructionAny well being tested sh