NAPL Mobility - Revision history

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2020-09-16T16:26:53Z

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Jhurley at 20:10, 25 June 2020

2020-06-25T20:10:16Z

Jhurley at 16:56, 17 June 2020

2020-06-17T16:56:42Z

Jhurley: /* LNAPL Mobility and Recovery Models */

2020-02-06T16:14:16Z

‎LNAPL Mobility and Recovery Models

Jhurley: /* LNAPL Mobility Conceptualized */

2020-02-06T16:06:55Z

‎LNAPL Mobility Conceptualized

Jhurley at 15:31, 6 February 2020

2020-02-06T15:31:08Z

Jhurley at 15:19, 6 February 2020

2020-02-06T15:19:39Z

Jhurley: /* LNAPL Mobility Conceptualized */

2020-02-05T21:28:07Z

‎LNAPL Mobility Conceptualized

Jhurley: /* LNAPL Mobility Conceptualized */

2020-02-05T21:25:17Z

‎LNAPL Mobility Conceptualized

Jhurley: /* Characterization of LNAPL Mobility */

2020-02-05T21:12:51Z

‎Characterization of LNAPL Mobility

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 '''Related Article(s):'''
 *LNAPL Source Zone Conceptual Models (Coming soon)
-*LNAPL Remediation Technologies (Coming soon)
+*[[LNAPL Remediation Technologies]]

@@ Line 2: / Line 2: @@
 <div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
-'''Related Article(s)''':
+'''Related Article(s):'''
 *LNAPL Source Zone Conceptual Models (Coming soon)
 *LNAPL Remediation Technologies (Coming soon)
@@ Line 10: / Line 10: @@
-'''Key Resource(s)''':
+'''Key Resource(s):'''
 *[https://lnapl-3.itrcweb.org LNAPL Site Management: LCSM Evolution, Decision Process, and Remedial Technologies]<ref name= "ITRC2018">ITRC, 2018. LNAPL Site Management: LCSM evolution, decision process, and remedial technologies (LNAPL-3). Interstate Technical and Regulatory Council https://lnapl-3.itrcweb.org/</ref>. Section 3 provides an introductory discussion of LNAPL mobility concepts.
 *[https://www.api.org/oil-and-natural-gas/environment/clean-water/ground-water/lnapl/ldrm API LNAPL Distribution and Recovery Model (LDRM), API 4760] <ref name= "Charbeneau2007">Charbeneau, R.J., 2007. LNAPL Distribution and Recovery Model. Distribution and Recovery of Petroleum Hydrocarbon Liquids in Porous Media. Vol. 1. API Publication 4760. [[media:API2007_LDRM.pdf | Report.pdf]] https://www.api.org/oil-and-natural-gas/environment/clean-water/ground-water/lnapl/ldrm</ref>.  Provides detailed discussion of LNAPL mobility as related to saturation, soil properties and capillary pressure.

@@ Line 94: / Line 94: @@
 *[https://www.api.org/oil-and-natural-gas/environment/clean-water/ground-water/lnapl/ldrm API LNAPL Distribution and Recovery Model (LDRM), API 4760]<ref name= "Charbeneau2007"/> – Addresses the recoverability of LNAPL in terms of time, induced drawdown, well spacing and residual fraction.
-*[https://www.epa.gov/water-research/hydrocarbon-spill-screening-model-hssm-windows-version Hydrocarbon Spill Screening Model (HSSM)]<ref>Weaver, J.W., Charbeneau, R.J., Tauxe, J.D., Lien, B.K. and Provost, J.B., 1995. The Hydrocarbon spill screening model (HSSM) Volume 1: User’s Guide. US EPA, publication EPA/600/R-94/039a, 229pp. [[media:Weaver1995_HSSMv1.pdf | Report.pdf]]</ref> – Evaluates potential risks of releases and promotes continuing improvement towards prevention.
+*[https://www.epa.gov/water-research/hydrocarbon-spill-screening-model-hssm-windows-version Hydrocarbon Spill Screening Model (HSSM)]<ref>Weaver, J.W., Charbeneau, R.J., Tauxe, J.D., Lien, B.K. and Provost, J.B., 1995. The Hydrocarbon spill screening model (HSSM) Volume 1: User’s Guide. US EPA, publication EPA/600/R-94/039a, 229pp. [[media:Weaver1995_HSSMv1.pdf | Report.pdf]] https://www.epa.gov/water-research/hydrocarbon-spill-screening-model-hssm-windows-version</ref> – Evaluates potential risks of releases and promotes continuing improvement towards prevention.
 ==LNAPL Mobility and Risk ==

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 [[File:Kirkman1w2Fig2.png|thumb|Figure 2.  Hypothetical relative permeability curves for water and an LNAPL in a porous medium<ref name= "USEPA1996"/><ref>Newell, C. J., Acree*, S. D., Ross, R.R., and Huling, S.G. 1995. Light non-aqueous phase liquid. U.S. Environmental Protection Agency, Washington, DC. EPA/540/S-95/500 (NTIS 95-267738) [[media:Newell1995_EPA_540_S-95_500_lnapl.pdf | Report.pdf]]</ref><ref>Williams, D.E. and Wilder, D.G., 1971. Gasoline Pollution of a Ground‐Water Reservoir—A Case History. Groundwater, 9(6), pp.50-56. [https://doi.org/10.1111/j.1745-6584.1971.tb03577.x doi: 10.1111/j.1745-6584.1971.tb03577.x]</ref>.]]
-LNAPL mobility can be described mathematically by Darcy’s Law, an empirically derived equation describing the flow of fluids through porous media where the specific discharge, ''q'', is equal to the product of the hydraulic conductivity, ''K'', and the hydraulic gradient, ''i''.  While this is the same Darcy’s Law that is used to describe groundwater flow (see [[Advection and Groundwater Flow]]), there is an important additional term, Relative Permeability, that is included when using Darcy’s Law to describe the flow of LNAPL in the subsurface.  Relative permeability is the ratio of the effective permeability of a fluid at a specified saturation to the intrinsic permeability of the medium at 100-percent saturation<ref>Mercer, J.W. and Cohen, R.M., 1990. A review of immiscible fluids in the subsurface: properties, models, characterization and remediation. Journal of contaminant hydrology, 6(2), pp.107-163. [https://doi.org/10.1016/0169-7722(90)90043-G doi: 10.1016/0169-7722(90)90043-G]</ref>.  The USEPA (1996)<ref name= "USEPA1996">USEPA, 1996.  How to effectively recover free product at leaking underground storage sites.  A guide for state regulators.  USEPA 510-R-96-001.  U.S. Environmental Protection Agency, 162 pp. [[media:USEPA1996_510_R-96_001_Recover_Free_Prod_at_LUSTS.pdf| Report.pdf]]</ref> describes relative permeability this way:
+LNAPL mobility can be described mathematically by Darcy’s Law, an empirically derived equation describing the flow of fluids through porous media where the specific discharge, ''q'', is equal to the product of the hydraulic conductivity, ''K'', and the hydraulic gradient, ''i''.  While this is the same Darcy’s Law that is used to describe groundwater flow (see [[Advection and Groundwater Flow]]), there is an important additional term, Relative Permeability, that is included when using Darcy’s Law to describe the flow of LNAPL in the subsurface.  Relative permeability is the ratio of the effective permeability of a fluid at a specified saturation to the intrinsic permeability of the medium at 100-percent saturation<ref>Mercer, J.W. and Cohen, R.M., 1990. A review of immiscible fluids in the subsurface: properties, models, characterization and remediation. Journal of contaminant hydrology, 6(2), pp.107-163. [https://doi.org/10.1016/0169-7722(90)90043-G doi: 10.1016/0169-7722(90)90043-G]</ref>.  The USEPA (1996) describes relative permeability this way:
-<q>''The relative permeability of a particular geologic media that is completely saturated with a particular fluid is equal to the intrinsic permeability. When more than one fluid (i.e., air, water, petroleum hydrocarbon) exists in a porous medium, the fluids compete for pore space thereby reducing the relative permeability of the media and the mobility of the fluid. This reduction can be quantified by multiplying the intrinsic permeability of the geologic media by the relative permeability. As with saturation, the mobility of each fluid phase present varies from zero (0% saturation) to one (100% saturation).''</q>
+<blockquote>''The relative permeability of a particular geologic media that is completely saturated with a particular fluid is equal to the intrinsic permeability. When more than one fluid (i.e., air, water, petroleum hydrocarbon) exists in a porous medium, the fluids compete for pore space thereby reducing the relative permeability of the media and the mobility of the fluid. This reduction can be quantified by multiplying the intrinsic permeability of the geologic media by the relative permeability. As with saturation, the mobility of each fluid phase present varies from zero (0% saturation) to one (100% saturation).''<ref name= "USEPA1996">USEPA, 1996.  How to effectively recover free product at leaking underground storage sites.  A guide for state regulators.  USEPA 510-R-96-001.  U.S. Environmental Protection Agency, 162 pp. [[media:USEPA1996_510_R-96_001_Recover_Free_Prod_at_LUSTS.pdf| Report.pdf]]</ref></blockquote>
 Figure 2 shows an example of relative permeability curves for a water-LNAPL system. The curves representing water saturation (starting at top right, blue line) and hydrocarbon saturation (starting at top left, red line) are contrary to one another and divide the figure into three flow zones. Zone I, where hydrocarbon saturation is relatively high, is dominated by hydrocarbon flow.  Water saturation is relatively high in Zone III, and therefore water flow is dominant. Flow of both water and LNAPL characterizes Zone II.

@@ Line 12: / Line 12: @@
 '''Key Resource(s)''':
 *[https://lnapl-3.itrcweb.org LNAPL Site Management: LCSM Evolution, Decision Process, and Remedial Technologies]<ref name= "ITRC2018">ITRC, 2018. LNAPL Site Management: LCSM evolution, decision process, and remedial technologies (LNAPL-3). Interstate Technical and Regulatory Council https://lnapl-3.itrcweb.org/</ref>. Section 3 provides an introductory discussion of LNAPL mobility concepts.
-*[https://www.api.org/oil-and-natural-gas/environment/clean-water/ground-water/lnapl/ldrm API LNAPL Distribution and Recovery Model (LDRM), API 4760] <ref name= "Charbeneau2007">Charbeneau, R.J., 2007. LNAPL Distribution and Recovery Model. Distribution and Recovery of Petroleum Hydrocarbon Liquids in Porous Media. Vol. 1. API Publication 4760. [[media:API2007_LDRM.pdf | Report.pdf]]</ref>.  Provides detailed discussion of LNAPL mobility as related to saturation, soil properties and capillary pressure.
+*[https://www.api.org/oil-and-natural-gas/environment/clean-water/ground-water/lnapl/ldrm API LNAPL Distribution and Recovery Model (LDRM), API 4760] <ref name= "Charbeneau2007">Charbeneau, R.J., 2007. LNAPL Distribution and Recovery Model. Distribution and Recovery of Petroleum Hydrocarbon Liquids in Porous Media. Vol. 1. API Publication 4760. [[media:API2007_LDRM.pdf | Report.pdf]] https://www.api.org/oil-and-natural-gas/environment/clean-water/ground-water/lnapl/ldrm</ref>.  Provides detailed discussion of LNAPL mobility as related to saturation, soil properties and capillary pressure.
-*[https://www.crccare.com/files/dmfile/CRCCARETechnicalreport44_TechnicalmeasurementguidanceforLNAPLnaturalsourcezonedepletion.pdf Technical measurement guidance for LNAPL natural source zone depletion]<ref name= "CRCCARE2018">CRC CARE, 2018. Technical measurement guidance for LNAPL natural source zone depletion. Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Newcastle, Australia. Technical Report no. 44. 254p [[media:CRCCARE2018_Measurement_Guidance_for_LNAPL_NSZD.pdf | Report.pdf]]</ref>. Section 6 provides a discussion of compositional changes to LNAPL over time and how to use those changes to calculate natural source zone depletion rates.
+*[https://www.crccare.com/files/dmfile/CRCCARETechnicalreport44_TechnicalmeasurementguidanceforLNAPLnaturalsourcezonedepletion.pdf Technical measurement guidance for LNAPL natural source zone depletion]<ref name= "CRCCARE2018">CRC CARE, 2018. Technical measurement guidance for LNAPL natural source zone depletion. Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Newcastle, Australia. Technical Report no. 44. 254p [[media:CRCCARE2018_Measurement_Guidance_for_LNAPL_NSZD.pdf | Report.pdf]]  https://www.crccare.com/files/dmfile/CRCCARETechnicalreport44_TechnicalmeasurementguidanceforLNAPLnaturalsourcezonedepletion.pdf</ref>. Section 6 provides a discussion of compositional changes to LNAPL over time and how to use those changes to calculate natural source zone depletion rates.
 ==Introduction==
@@ Line 31: / Line 31: @@
 Figure 1 shows a research tank with a well screen in a porous media (sand) containing LNAPL.  The LNAPL fluoresces under ultraviolet (UV) light, while water and air do not.  The column of yellow fluorescence in the well represents the gauged LNAPL thickness and corresponds to the vertical interval over which LNAPL flows in the formation<ref name= "Huntley2000">Huntley, D., 2000. Analytic determination of hydrocarbon transmissivity from baildown tests. Groundwater, 38(1), pp.46-52. [https://doi.org/10.1111/j.1745-6584.2000.tb00201.x doi: 10.1111/j.1745-6584.2000.tb00201.x]</ref>.  The yellow fluorescence to the left of the well represents LNAPL occurring within soil pores.  Below the potentiometric surface line, the pores are dominated by water (dark pores) and LNAPL.  Above this line LNAPL and water still exist in pores, but the air saturation increases with elevation.  The incomplete yellow fluorescence in the formation illustrates how water and LNAPL occupy pores over the mobile interval.  This occurs because the mobile LNAPL cannot displace all of the water from the pores.
-[[File:Kirkman1w2Fig2.png|thumb|Figure 2.  Hypothetical relative permeability curves for water and an LNAPL in a porous medium<ref name= "USEPA1996"/><ref>Newell, C. J., Acree*, S. D., Ross, R.R., and Huling, S.G. 1995. Light non-aqueous phase liquid. U.S. Environmental Protection Agency, Washington, DC. EPA/540/S-95/500 (NTIS 95-267738) [[media:Newell1995_EPA_540_S-95_500_lnapl.pdf | Report.pdf]]</ref><ref>Williams, D.E. and Wilder, D.G., 1971. Gasoline Pollution of a Ground‐Water Reservoir—A Case History a. Groundwater, 9(6), pp.50-56. [https://doi.org/10.1111/j.1745-6584.1971.tb03577.x doi: 10.1111/j.1745-6584.1971.tb03577.x]</ref>.]]
+[[File:Kirkman1w2Fig2.png|thumb|Figure 2.  Hypothetical relative permeability curves for water and an LNAPL in a porous medium<ref name= "USEPA1996"/><ref>Newell, C. J., Acree*, S. D., Ross, R.R., and Huling, S.G. 1995. Light non-aqueous phase liquid. U.S. Environmental Protection Agency, Washington, DC. EPA/540/S-95/500 (NTIS 95-267738) [[media:Newell1995_EPA_540_S-95_500_lnapl.pdf | Report.pdf]]</ref><ref>Williams, D.E. and Wilder, D.G., 1971. Gasoline Pollution of a Ground‐Water Reservoir—A Case History. Groundwater, 9(6), pp.50-56. [https://doi.org/10.1111/j.1745-6584.1971.tb03577.x doi: 10.1111/j.1745-6584.1971.tb03577.x]</ref>.]]
 LNAPL mobility can be described mathematically by Darcy’s Law, an empirically derived equation describing the flow of fluids through porous media where the specific discharge, ''q'', is equal to the product of the hydraulic conductivity, ''K'', and the hydraulic gradient, ''i''.  While this is the same Darcy’s Law that is used to describe groundwater flow (see [[Advection and Groundwater Flow]]), there is an important additional term, Relative Permeability, that is included when using Darcy’s Law to describe the flow of LNAPL in the subsurface.  Relative permeability is the ratio of the effective permeability of a fluid at a specified saturation to the intrinsic permeability of the medium at 100-percent saturation<ref>Mercer, J.W. and Cohen, R.M., 1990. A review of immiscible fluids in the subsurface: properties, models, characterization and remediation. Journal of contaminant hydrology, 6(2), pp.107-163. [https://doi.org/10.1016/0169-7722(90)90043-G doi: 10.1016/0169-7722(90)90043-G]</ref>.  The USEPA (1996)<ref name= "USEPA1996">USEPA, 1996.  How to effectively recover free product at leaking underground storage sites.  A guide for state regulators.  USEPA 510-R-96-001.  U.S. Environmental Protection Agency, 162 pp. [[media:USEPA1996_510_R-96_001_Recover_Free_Prod_at_LUSTS.pdf| Report.pdf]]</ref> describes relative permeability this way:

@@ Line 31: / Line 31: @@
 Figure 1 shows a research tank with a well screen in a porous media (sand) containing LNAPL.  The LNAPL fluoresces under ultraviolet (UV) light, while water and air do not.  The column of yellow fluorescence in the well represents the gauged LNAPL thickness and corresponds to the vertical interval over which LNAPL flows in the formation<ref name= "Huntley2000">Huntley, D., 2000. Analytic determination of hydrocarbon transmissivity from baildown tests. Groundwater, 38(1), pp.46-52. [https://doi.org/10.1111/j.1745-6584.2000.tb00201.x doi: 10.1111/j.1745-6584.2000.tb00201.x]</ref>.  The yellow fluorescence to the left of the well represents LNAPL occurring within soil pores.  Below the potentiometric surface line, the pores are dominated by water (dark pores) and LNAPL.  Above this line LNAPL and water still exist in pores, but the air saturation increases with elevation.  The incomplete yellow fluorescence in the formation illustrates how water and LNAPL occupy pores over the mobile interval.  This occurs because the mobile LNAPL cannot displace all of the water from the pores.
-[[File:Kirkman1w2Fig2.png|thumb|Figure 2.  Hypothetical relative permeability curves for water and an LNAPL in a porous medium<ref name= "USEPA1996"/><ref>Newell, C. J., S. D. Acree*, Ross, R.R., and Huling, S.G. 1995. Light non-aqueous phase liquid. U.S. Environmental Protection Agency, Washington, DC. EPA/540/S-95/500 (NTIS 95-267738) [[media:Newell1995_EPA_540_S-95_500_lnapl.pdf | Report.pdf]]</ref><ref>Williams, D.E. and Wilder, D.G., 1971. Gasoline Pollution of a Ground‐Water Reservoir—A Case History a. Groundwater, 9(6), pp.50-56. [https://doi.org/10.1111/j.1745-6584.1971.tb03577.x doi: 10.1111/j.1745-6584.1971.tb03577.x]</ref>.]]
+[[File:Kirkman1w2Fig2.png|thumb|Figure 2.  Hypothetical relative permeability curves for water and an LNAPL in a porous medium<ref name= "USEPA1996"/><ref>Newell, C. J., Acree*, S. D., Ross, R.R., and Huling, S.G. 1995. Light non-aqueous phase liquid. U.S. Environmental Protection Agency, Washington, DC. EPA/540/S-95/500 (NTIS 95-267738) [[media:Newell1995_EPA_540_S-95_500_lnapl.pdf | Report.pdf]]</ref><ref>Williams, D.E. and Wilder, D.G., 1971. Gasoline Pollution of a Ground‐Water Reservoir—A Case History a. Groundwater, 9(6), pp.50-56. [https://doi.org/10.1111/j.1745-6584.1971.tb03577.x doi: 10.1111/j.1745-6584.1971.tb03577.x]</ref>.]]
 LNAPL mobility can be described mathematically by Darcy’s Law, an empirically derived equation describing the flow of fluids through porous media where the specific discharge, ''q'', is equal to the product of the hydraulic conductivity, ''K'', and the hydraulic gradient, ''i''.  While this is the same Darcy’s Law that is used to describe groundwater flow (see [[Advection and Groundwater Flow]]), there is an important additional term, Relative Permeability, that is included when using Darcy’s Law to describe the flow of LNAPL in the subsurface.  Relative permeability is the ratio of the effective permeability of a fluid at a specified saturation to the intrinsic permeability of the medium at 100-percent saturation<ref>Mercer, J.W. and Cohen, R.M., 1990. A review of immiscible fluids in the subsurface: properties, models, characterization and remediation. Journal of contaminant hydrology, 6(2), pp.107-163. [Mercer, J.W. and Cohen, R.M., 1990. A review of immiscible fluids in the subsurface: properties, models, characterization and remediation. Journal of contaminant hydrology, 6(2), pp.107-163. [https://doi.org/10.1016/0169-7722(90)90043-G doi: 10.1016/0169-7722(90)90043-G]</ref>.  The USEPA (1996)<ref name= "USEPA1996">USEPA, 1996.  How to effectively recover free product at leaking underground storage sites.  A guide for state regulators.  USEPA 510-R-96-001.  U.S. Environmental Protection Agency, 162 pp. [[media:USEPA1996_510_R-96_001_Recover_Free_Prod_at_LUSTS.pdf| Report.pdf]]</ref> describes relative permeability this way:
@@ Line 43: / Line 43: @@
 LNAPL saturation varies with elevation across the gauged LNAPL thickness, where LNAPL conductivity is lowest near the oil/water interface and highest near the air/LNAPL interface.  To provide a single metric for LNAPL mobility, the conductivity must be summed across the mobile LNAPL interval to give the LNAPL transmissivity.
-LNAPL transmissivity has been identified as a key metric for evaluating the likely effectiveness of direct LNAPL recovery compared to traditional measurements such as gauged LNAPL thickness in monitoring wells<ref>Kolhatkar, R., Kremesec, V., Rubin, S., Yukawa, C. and Senn, R., 1999. Application of field and analytical techniques to evaluate recoverability of subsurface free phase hydrocarbons. Petroleum Hydrocarbons and Organic Chemicals in Ground Water, pp.5-15.</ref><ref>Lundy, D.A. and Zimmerman, L.M., 1996, May. Assessing the recoverability of LNAPL plumes for recovery system conceptual design. In Proceedings of the 10th National Outdoor Action Conference and Expo (pp. 13-15).</ref><ref name= "Huntley2000"/><ref name= "Kirman2013">Kirkman, A.J., 2013. Refinement of Bouwer‐Rice baildown test analysis. Groundwater Monitoring & Remediation, 33(1), pp.105-110. [https://doi.org/10.1111/j.1745-6592.2012.01411.x  doi: 10.1111/j.1745-6592.2012.01411.x]</ref><ref name= "ASTM2013">ASTM, 2013.  ASTM E2856-13, Standard guide for estimation of LNAPL transmissivity, ASTM International, West Conshohocken, PA.</ref><ref name= "Charbeneau2016">Charbeneau, R., A. Kirkman, and R. Muthu, 2016.  API LNAPL Transmissivity Workbook: A Tool for Baildown Test Analysis – User Guide.  American Petroleum Institute Publication 4762.</ref><ref name= "Palmier2016">Palmier, C., Dodt, M. and Atteia, O., 2016. Comparison of Oil Transmissivity Methods Using Bail‐Down Test Data. Groundwater Monitoring & Remediation, 36(3), pp.73-83.[[media:Palmier2016_LNAPLBaildownTesting.pdf| Report.pdf]]</ref><ref>Lenhard, R.J., Rayner, J.L. and Davis, G.B., 2017. A practical tool for estimating subsurface LNAPL distributions and transmissivity using current and historical fluid levels in groundwater wells: Effects of entrapped and residual LNAPL. Journal of contaminant hydrology, 205, pp.1-11. [[media:Lenhard2017_Estimating_Subsurface_LNAPL.pdf | Report.pdf]]</ref>.  LNAPL transmissivity represents the volume of LNAPL flow a formation can produce per unit time over a unit width for a unit hydraulic gradient.  Aquifer transmissivity is the primary metric for evaluating how much water can be produced from a water bearing unit in the subsurface and accounts for the thickness of the saturated aquifer and the ease with which the aquifer can transmit a given fluid per unit volume. The concept of transmissivity is illustrated in Figure 3.  It is reasonable to apply similar thinking to estimation of the amount of LNAPL that could be produced by a particular subsurface matrix, and therefore transmissivity has become a key metric used to predict whether direct recovery (direct pumping) of LNAPL is likely to be effective.
+LNAPL transmissivity has been identified as a key metric for evaluating the likely effectiveness of direct LNAPL recovery compared to traditional measurements such as gauged LNAPL thickness in monitoring wells<ref>Kolhatkar, R., Kremesec, V., Rubin, S., Yukawa, C. and Senn, R., 1999. Application of field and analytical techniques to evaluate recoverability of subsurface free phase hydrocarbons. Petroleum Hydrocarbons and Organic Chemicals in Ground Water, pp.5-15.</ref><ref>Lundy, D.A. and Zimmerman, L.M., 1996, May. Assessing the recoverability of LNAPL plumes for recovery system conceptual design. In Proceedings of the 10th National Outdoor Action Conference and Expo (pp. 13-15).</ref><ref name= "Huntley2000"/><ref name= "Kirman2013">Kirkman, A.J., 2013. Refinement of Bouwer‐Rice baildown test analysis. Groundwater Monitoring & Remediation, 33(1), pp.105-110. [https://doi.org/10.1111/j.1745-6592.2012.01411.x  doi: 10.1111/j.1745-6592.2012.01411.x]</ref><ref name= "ASTM2013">ASTM, 2013.  ASTM E2856-13, Standard guide for estimation of LNAPL transmissivity, ASTM International, West Conshohocken, PA.</ref><ref name= "Charbeneau2016">Charbeneau, R., Kirkman, A., and  Muthu, R., 2016.  API LNAPL Transmissivity Workbook: A Tool for Baildown Test Analysis – User Guide.  American Petroleum Institute Publication 4762.</ref><ref name= "Palmier2016">Palmier, C., Dodt, M. and Atteia, O., 2016. Comparison of Oil Transmissivity Methods Using Bail‐Down Test Data. Groundwater Monitoring & Remediation, 36(3), pp.73-83.[[media:Palmier2016_LNAPLBaildownTesting.pdf| Report.pdf]]</ref><ref>Lenhard, R.J., Rayner, J.L. and Davis, G.B., 2017. A practical tool for estimating subsurface LNAPL distributions and transmissivity using current and historical fluid levels in groundwater wells: Effects of entrapped and residual LNAPL. Journal of contaminant hydrology, 205, pp.1-11. [[media:Lenhard2017_Estimating_Subsurface_LNAPL.pdf | Report.pdf]]</ref>.  LNAPL transmissivity represents the volume of LNAPL flow a formation can produce per unit time over a unit width for a unit hydraulic gradient.  Aquifer transmissivity is the primary metric for evaluating how much water can be produced from a water bearing unit in the subsurface and accounts for the thickness of the saturated aquifer and the ease with which the aquifer can transmit a given fluid per unit volume. The concept of transmissivity is illustrated in Figure 3.  It is reasonable to apply similar thinking to estimation of the amount of LNAPL that could be produced by a particular subsurface matrix, and therefore transmissivity has become a key metric used to predict whether direct recovery (direct pumping) of LNAPL is likely to be effective.
 The average LNAPL recovery rate was shown to be closely related to the average LNAPL transmissivity as well as to the LNAPL thickness in a series of 10-hour pump tests of three wells at an LNAPL-impacted site (Table 1, ITRC 2018)<ref name= "ITRC2018"/>.  The measured LNAPL thickness in the source well (MW-1) was 3.7 times higher than in the LNAPL fringe well (MW-3), while the ratio of their average LNAPL transmissivities was 5. The average recovery rate was 12 times greater at the source well than at the fringe well.  In this study, LNAPL thickness, average transmissivity and average recovery rate were all strongly correlated, with correlation coefficients of 0.94 and above.

@@ Line 79: / Line 79: @@
 *Tracer-Based Method:  An emerging, less common method involving placing fluorescent dyes that are soluble in LNAPL but not water into a well.  The dye concentration is measured over time to calculate the LNAPL flux through the well.
-Two comparative studies have shown that different LNAPL transmissivity measurement techniques yield similar results<ref name= "Palmier2016"/><ref name= "Kirman2013"/>).  For sites with more complex conditions such as perched LNAPL, confined LNAPL, and changes in potentiometric surface, see ASTM Standard E2856-13 (ASTM 2013)<ref name= "ASTM2013"/> and Kirkman et al. (2013)<ref name= "Kirkman2_2013"/>.
+Two comparative studies have shown that different LNAPL transmissivity measurement techniques yield similar results<ref name= "Palmier2016"/><ref name= "Kirman2013"/>).  For sites with more complex conditions such as perched LNAPL, confined LNAPL, and changes in potentiometric surface, see ASTM Standard E2856-13<ref name= "ASTM2013"/> and Kirkman et al. (2013)<ref name= "Kirkman2_2013"/>.
 In addition to field testing, LNAPL transmissivity can also be estimated using an appropriate computer-based model, although it is best to calibrate the model to observed field values initially. Please see LNAPL Mobility and Recovery Models (below) for more on this topic.