1、Designation: E2856 111 E2856 12Standard 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 p
2、arentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1 NOTEEditorial changes were made throughout in January 2012.1. Scope1.1 This guide provides field data collection and calculation methodologies for the estim
3、ation of light non-aqueous phase liquid(LNAPL) transmissivity in unconsolidated porous sediments. The methodologies presented herein may, or may not be, applicableto other hydrogeologic regimes (for example, karst, fracture flow). LNAPL transmissivity represents the volume of LNAPL (L3)through a uni
4、t width (L) of aquifer per unit time (t) per unit drawdown (L) with units of (L2/T). LNAPL transmissivity is a directlyproportional metric for LNAPL recoverability whereas other metrics such as apparent LNAPL thickness gauged in wells do notexhibit a consistent relationship to recoverability. The re
5、coverability for a given gauged LNAPL thickness in a well will varybetween different soil types, LNAPL types or hydrogeologic conditions. LNAPL transmissivity accounts for those parameters andconditions. LNAPL transmissivity values can be used in the following five ways: (1) Estimate LNAPL recovery
6、rate for multipletechnologies; (2) Identify trends in recoverability via mapping; (3) Applied as a leading (startup) indicator for recovery; (4) Appliedas a lagging (shutdown) indicator for LNAPL recovery; and (5) Applied as a robust calibration metric for multi-phase models(Hawthorne and Kirkman, 2
7、011 (1)2 and ITRC (2). The methodologies for LNAPL transmissivity estimation provided in thisdocument include short-term aquifer testing methods (LNAPL baildown/slug testing and manual LNAPL skimming testing), andlong-term methods (that is, LNAPL recovery system performance analysis, and LNAPL trace
8、r testing). The magnitude oftransmissivity of any fluid in the subsurface is controlled by the same variables (that is, fluid pore space saturation, soilpermeability, fluid density, fluid viscosity, the interval that LNAPL flows over in the formation and the gravitational accelerationconstant). A di
9、rect mathematical relationship exists between the transmissivity of a fluid and the discharge of that fluid for a giveninduced drawdown. The methodologies are generally aimed at measuring the relationship of discharge versus drawdown for theoccurrence of LNAPL in a well, which can be used to estimat
10、e the transmissivity of LNAPL in the formation. The focus, therefore,is to provide standard methodology on how to obtain accurate measurements of these two parameters (that is, discharge anddrawdown) for multi-phase occurrences to estimate LNAPL transmissivity.1.2 Organization of this Guide:1.2.1 Se
11、ction 2 presents documents 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 methods for data collection related to LNAPL transmissivity calculation.This section compares and contrasts the methods i
12、n a way that will allow a user of this guide to assess which method most closelyaligns with the site conditions and available data collection opportunities.1.2.5 Sections 6 and 7 presents the test methods for each of the four data collection options. After reviewing Section 5 andselecting a test met
13、hod, a user of this guide shall then proceed to the applicable portion of Sections 6 and 7 which describes thedetailed test methodology for the selected method.1.2.6 Section 8 presents data evaluation methods. After reviewing Section 5 and the pertinent test method section(s) of Sections6 and 7, the
14、 user of this guide shall then proceed to the applicable portion(s) of Section 8 to understand the methodologies forevaluation of the data which will be collected. It is highly recommended that the test methods and data evaluation procedures beunderstood prior to initiating data collection.1.3 The v
15、alues stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard.1 This guide is under the jurisdiction of ASTM Committee E50 on Environmental Assessment, Ri
16、sk Management and Corrective Action and is the direct responsibilityof Subcommittee E50.04 on Corrective Action.Current edition approved Nov. 1, 2011Oct. 1, 2012. Published January 2012January 2013. Originally approved in 2011. Last previous edition approved in 2011 asE2856 111. DOI: 10.1520/E285611
17、.10.1520/E285612.2 The boldface numbers in parentheses refer to the list of references at the end of this standard.This 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 no
18、t be technically 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 D
19、rive, PO Box C700, West Conshohocken, PA 19428-2959. United States11.4 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 ap
20、plicability of regulatorylimitations prior to use.1.5 This document is applicable to wells exhibiting LNAPL consistently (that is, LNAPL transmissivity values above zero). Thismethodology does not substantiate zero LNAPL transmissivity; rather the lack of detection of LNAPL within the well combinedw
21、ith proper well development and purging procedures are required to confirm zero LNAPL transmissivity.1.6 This document cannot replace education or experience and should be used in conjunction with professional competence inthe hydrogeology field and expertise in the behavior of LNAPL in the subsurfa
22、ce.1.7 This document cannot be assumed to be a substitute for or replace any laws or regulations whether federal, state, tribal orlocal.2. Referenced Documents2.1 ASTM Standards:3D653 Terminology Relating to Soil, Rock, and Contained FluidsD5088 Practice for Decontamination of Field Equipment Used a
23、t Waste SitesD5521 Guide for Development of Ground-Water Monitoring Wells in Granular AquifersE2531 Guide for Development of Conceptual Site Models and Remediation Strategies for Light Nonaqueous-Phase LiquidsReleased to the Subsurface3. Terminology3.1 Definitions:3.1.1 air/LNAPL interface (Zan)The
24、surface shared by air and LNAPL in a control well. (L)3.1.2 calculated water-table elevation (ZCGW) )the theoretical location of the air/water surface based on a density correctionif LNAPL were not present in a well. (L)3.1.3 confined LNAPLLNAPL trapped in an aquifer beneath a layer that exhibits a
25、pore entry pressure greater than thecapillary LNAPL head, thereby impeding the upward migration of LNAPL limits the upward movement of the LNAPL. The termconfined LNAPL is used because the mobile LNAPL is under pressure greater than gauge pressure against the underside of theLNAPL confining layer.3.
26、1.4 control wellwell by which the aquifer is stressed or tested.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 fluid head. (L)3.1.7 effective well radiusthe radius that represents the area of the well casing and the interconnected po
27、rosity of the filterpack. (L)3.1.8 equilibrium fluid levelsgauged fluid levels that represent the oil head and the water head or the calculated water-tableelevation of the formation. Under equilibrium fluid levels no net oil or water flow occurs between the formation and the well.3.1.9 fluid levelth
28、e level of a fluid interface (either air/oil, LNAPL/water, or potentiometric surface).3.1.10 formation thickness (bnf)the interval that LNAPL flows over in the formation. For unconfined conditions this isapproximately equal to the gauged LNAPL thickness. Confined and perched conditions the gauged LN
29、APL thickness underequilibrium conditions is not equal to the formation thickness. (L)3.1.11 gauged LNAPL thickness (bn) )The difference between the gauged air/LNAPL interface and the water/LNAPLinterface in a well. (L)3.1.12 hydraulic conductivity (derived via field aquifer tests)the volume of wate
30、r at the existing kinematic viscosity that willmove in a unit time, under a unit hydraulic gradient, through a unit area, measured at right angles to the direction of flow. (L/t)3.1.13 LNAPLLight Non Aqueous Phase Liquid.3.1.14 LNAPL baildown testa procedure which includes the act of removing a meas
31、ured LNAPL volume from a well and filterpack to induce a head differential and the follow-up gauging of fluid levels in the well.3.1.15 LNAPL borehole volumethe volume of LNAPL existing within the casing and the drainable volume existing within thefilter pack of a well. Based on effective radius and
32、 gauged thickness of LNAPL. (L3)3.1.16 LNAPL slug testa procedure which includes the act of removing or displacing a known volume of LNAPL from a wellto induce a head differential and the follow-up gauging of fluid levels in the well.3 For referenced ASTM standards, visit the ASTM website, www.astm.
33、org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.E2856 1223.1.17 LNAPL specific yield (Syn)the volume of LNAPL an aquifer releases or takes into storage per unit surface are
34、a of theaquifer per unit change in LNAPL head for gravity drainage conditions. (unitless)3.1.18 LNAPL specific yield filter pack (Syf) the volume of LNAPL released or takes into storage per unit surface area of thefilter pack per unit change in LNAPL head for gravity drainage conditions. (unitless)3
35、.1.19 LNAPL storage coeffcient (Sn) the volume of LNAPL an aquifer releases from or takes into storage per unit surfacearea of the aquifer per unit change in LNAPL head. For a confined aquifer, it is based on the volume of fluid released due todecompression. For an unconfined aquifer, the storage co
36、efficient is approximately equal to the LNAPL specific yield. (unitless)3.1.20 LNAPL transmissivity (Tn)the volume of LNAPL at the existing kinematic viscosity that will move in a unit time undera unit hydraulic gradient through a unit width of the aquifer. (L2/t)3.1.21 observation wella well screen
37、ed across all or part of an aquifer.3.1.22 oil/water interface (Znw)The surface shared by LNAPL and water in a control well. (L)3.1.23 perched LNAPLmobile LNAPL that accumulates in the vadose zone of a site for some time period above a layer thatexhibits a pore entry pressure greater than the capill
38、ary LNAPL head, thereby impeding the downward migration of LNAPL.3.1.24 potentiometric surfacesee calculated water-table elevation.3.1.25 radius of influencethe distance from a well that the pumping induced head differential from non-pumping conditionsis zero, head differentials due to background gr
39、adients may still exist at this radius. (L)3.1.26 sluga volume of water or solid object used to induce a sudden change of head in a well.3.1.27 test wella well by which the aquifer is stressed, for example, by pumping, injection, or change of head.3.2 For definitions of other terms used in this test
40、 method refer to Terminology, Guide D653.4. Significance and Use4.1 Application:4.1.1 LNAPL transmissivity is an accurate metric for understanding LNAPL recovery, is directly proportional to LNAPLrecoverability and tracking remediation progress towards residual LNAPL saturation.4.1.2 LNAPL transmiss
41、ivity can be used to estimate the rate of recovery for a given drawdown from various technologies.4.1.3 LNAPL transmissivity is not an intrinsic aquifer property but rather a summary metric based on the aquifer properties,LNAPL physical properties, and the magnitude of LNAPL saturation over a given
42、interval of aquifer.4.1.4 LNAPL transmissivity will vary over time with changing conditions such as, seasonal fluctuations in water table, changinghydrogeologic conditions and with variability in LNAPL impacts (that is, interval that LNAPL flows over in the formation andLNAPL pore space saturation)
43、within the formation.4.1.5 Any observed temporal or spatial variability in values derived from consistent data collection and analysis methods ofLNAPL transmissivity is not erroneous, rather is indicative of the actual variability in subsurface conditions related to theparameters encompassed by LNAP
44、L transmissivity (that is, fluid pore space saturation, soil permeability, fluid density, fluidviscosity, and the interval that LNAPL flows over in the formation).4.1.6 LNAPL transmissivity is a more accurate metric for evaluating recoverability and mobile LNAPL than gauged LNAPLthickness. Gauged LN
45、APL thickness does not account for soil permeability, magnitude of LNAPL saturation above residualsaturation, or physical fluid properties of LNAPL (that is, density, interfacial tension, and viscosity).4.1.7 The accurate calculation of LNAPL transmissivity requires certain aspects of the LNAPL Conc
46、eptual Site Model(LSCM)(LCSM) to be completely understood and defined in order to calculate LNAPL drawdown correctly. The methodologiesfor development of the LSCMLCSM are provided in Guide E2531. The general conceptual site model aspects applicable to thisguide include:4.1.7.1 Equilibrium fluid leve
47、ls (for example, air/LNAPL and LNAPL/water).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 the well screen inte
48、rval.4.1.7.6 Well screen interval in the vadose and saturated zones.4.1.8 Incorporation of LNAPL transmissivity can further LSCMsLCSMs by providing a single comparable metric thatquantifies LNAPL recoverability at individual locations across a site.4.1.9 Each of the methods provided in this document
49、 is applicable to LNAPL in confined, unconfined, and perched conditions.Any differences in evaluation are discussed in Section 5.4.2 PurposeThe methods used to calculate LNAPL transmissivity have been published over the past 20 years; however littleeffort has been focused on providing quality assurance for individual tests or refinement of field procedures. In addition tosummarizing the existing methods to calculate LNAPL transmissivity, this document will provide guidance on refined fieldprocedures for data collection and minimum requirements
