1、Designation: E2856 13Standard 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 April 1, 2013. Published M
18、ay 2013. Originallyapproved in 2011. Last previous edition approved in 2012 as E2856 12. DOI:10.1520/E285613.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2
19、959. United States1combined 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 be
20、havior ofLNAPL 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 Decontaminati
21、on of Field EquipmentUsed at Waste SitesD5521 Guide for Development of Ground-Water MonitoringWells 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/
22、LNAPL interface (Zan)The surface shared by airand LNAPL in a control well. (L)3.1.2 calculated water-table elevation (ZCGW)the theoreti-cal 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
23、a layer that 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
24、LNAPL confining 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 t
25、he interconnected 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.
26、3.1.9 fluid 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 condition
27、s the gauged 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 vo
28、lume 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)3.1.13 LNAPLLight Non Aqueous Phase Liquid.3.1.14 LNAPL baildown testa procedure which includesthe act of removi
29、ng a measured LNAPL volume from a welland filter pack to induce a head differential and the follow-upgauging of fluid levels in the well.3.1.15 LNAPL borehole volumethe volume of LNAPLexisting within the casing and the drainable volume existingwithin the filter pack of a well. Based on effective rad
30、ius andgauged 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
31、 releases or 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
32、head for gravitydrainage 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 decompressi
33、on. For an unconfined 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. (
34、L2/t)3.1.21 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
35、entry pressure 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 D
36、ocument Summary page onthe ASTM website.E2856 1323.1.24 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
37、 exist at this 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 Ter
38、minology, Guide 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
39、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 magnitude ofLNAPL saturation over a given interval of aquifer.4
40、.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 theformation and LNAPL pore space saturation) within theformation.4.
41、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 related to theparameters encompassed by LNAPL transmissivity (that is
42、,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 than gaugedLNAPL thickness. Gauged LNAPL thickness does not accou
43、ntfor 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 certain aspects of the LNAPL Conceptual Site Model(LCSM) to be c
44、ompletely understood and defined in order tocalculate LNAPL drawdown correctly. The methodologies fordevelopment of the LCSM 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).
45、4.1.7.2 Soil profile over which LNAPL is mobile.4.1.7.3 LNAPL hydrogeologic scenario (for example,unconfined, 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 vados
46、e and saturatedzones.4.1.8 Incorporation of LNAPL transmissivity can furtherLCSMs 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 p
47、erchedconditions. 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 procedu
48、res. In addition tosummarizing the existing methods to calculate LNAPLtransmissivity, this document will provide guidance on refinedfield procedures for data collection and minimum requirementsfor data sets before they are used to calculate LNAPLtransmissivity.4.2.1 ConsiderationsThe following secti
49、on 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 toconfined, unconfined, and perched conditions; however, con-sideration should be given to how LNAPL drawdown iscalculated from well gauging data relative to formation condi-tions. Calculation of LNAPL transmissivity for confined andperched conditions is possible; however, the soil profile needsto be considered in combination with the fluid levels toaccurately ca
