REMChlor - MD - Revision history

Admin at 01:33, 28 April 2022

2022-04-28T01:33:48Z

Jhurley at 20:39, 13 November 2019

2019-11-13T20:39:01Z

Jhurley at 20:27, 13 November 2019

2019-11-13T20:27:24Z

Jhurley at 20:24, 13 November 2019

2019-11-13T20:24:11Z

Jhurley at 20:22, 13 November 2019

2019-11-13T20:22:17Z

Jhurley: /* Modeling Examples */

2019-11-13T20:18:21Z

‎Modeling Examples

Jhurley: links added and layout changes

2019-11-13T18:24:32Z

links added and layout changes

Jhurley: /* Matrix Diffusion of Dissolved Contaminants */

2019-11-13T18:13:26Z

‎Matrix Diffusion of Dissolved Contaminants

Jhurley: /* REMChlor-MD’s Modeling Approach */

2019-11-13T18:00:08Z

‎REMChlor-MD’s Modeling Approach

Debra Tabron at 14:54, 12 November 2019

2019-11-12T14:54:54Z

@@ Line 4: / Line 4: @@
 '''Related Article(s)''':
 *[[Dispersion and Diffusion]]
 *[[Source Zone Modeling]]
 *[[Plume Response Modeling]]
 *[[Matrix Diffusion]]
-'''CONTRIBUTOR(S):''' [[Dr. Ron Falta]] and [[Kien Pham]]
 '''Key Resource(s)''':
 *[https://www.serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Persistent-Contamination/ER-201426 REMChlor-MD Toolkit package]
@@ Line 29: / Line 32: @@
 Another type of numerical model of matrix diffusion is the dual-porosity model which is more computationally efficient because it uses a first order approximation to describe the mass transfer between the high K and low K zones. Dual-porosity models can be calibrated to match the effects of matrix diffusion on contaminant concentrations over short time periods.  However, the first order mass transfer coefficient is time-dependent<ref>Guan, J., Molz, F.J., Zhou, Q., Liu, H.H. and Zheng, C., 2008. Behavior of the mass transfer coefficient during the MADE‐2 experiment: New insights. Water Resources Research, 44(2). [https://doi.org/10.1029/2007WR006120 doi: 10.1029/2007WR006120]</ref>, so models calibrated to early time data will not accurately simulate concentrations at a later time.
-The REMChlor-MD model was developed under ESTCP project [https://www.serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Persistent-Contamination/ER-201426  ER-201426] to provide a practical alternative to previous approaches for modeling matrix diffusion.
+The REMChlor-MD model was developed under ESTCP project [https://www.serdp-estcp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Persistent-Contamination/ER-201426 ER-201426] to provide a practical alternative to previous approaches for modeling matrix diffusion.
 ==REMChlor-MD’s Modeling Approach==
-REMChlor-MD employs a semi-analytical method adapted from a heat diffusivity estimation strategy used in petroleum engineering and applied here to the problem of chemical diffusion with first order decay kinetics<ref>Vinsome, P.K.W. and Westerveld, J., 1980. A simple method for predicting cap and base rock heat losses in'thermal reservoir simulators. Journal of Canadian Petroleum Technology, 19(03).  Pp 87-90 [https://doi.org/10.2118/80-03-04 doi: 10.2118/80-03-04]</ref><ref name= "Falta2017">Falta, R.W. and Wang, W., 2017. A semi-analytical method for simulating matrix diffusion in numerical transport models. Journal of contaminant hydrology, 197, pp.39-49. [https://doi.org/10.1016/j.jconhyd.2016.12.007 doi: 10.1016/j.jconhyd.2016.12.007]</ref>.  This semi-analytical method utilizes a fitting function to describe the concentration of the chemical in the low K zones in, or adjacent to, each gridblock:
+REMChlor-MD employs a semi-analytical method adapted from a heat diffusivity estimation strategy used in petroleum engineering and applied here to the problem of chemical diffusion with first order decay kinetics<ref>Vinsome, P.K.W. and Westerveld, J., 1980. A simple method for predicting cap and base rock heat losses in'thermal reservoir simulators. Journal of Canadian Petroleum Technology, 19(03).  Pp 87-90 [https://doi.org/10.2118/80-03-04 doi: 10.2118/80-03-04]</ref><ref name="Falta2017">Falta, R.W. and Wang, W., 2017. A semi-analytical method for simulating matrix diffusion in numerical transport models. Journal of contaminant hydrology, 197, pp.39-49. [https://doi.org/10.1016/j.jconhyd.2016.12.007 doi: 10.1016/j.jconhyd.2016.12.007]</ref>.  This semi-analytical method utilizes a fitting function to describe the concentration of the chemical in the low K zones in, or adjacent to, each gridblock:
 {|
 |-
-| where:
+|where:
 |-
-| ''C<sub>l</sub>'' || represents the concentration in the low K material;
+|''C<sub>l</sub>''||represents the concentration in the low K material;
 |-
-| ''C<sup>t + &Delta;t</sup>'' || is the concentration in the high K zone during the next numerical time-step;
+|''C<sup>t + &Delta;t</sup>''||is the concentration in the high K zone during the next numerical time-step;
 |-
-| ''z<sub>l</sub>'' || is the distance into the low K zone from the high K / low K interface;
+|''z<sub>l</sub>''||is the distance into the low K zone from the high K / low K interface;
 |-
-| ''p'' and ''q''&nbsp;&nbsp;&nbsp;&nbsp; || are fitting parameters that can be solved for by enforcing the diffusion differential equation at the interface and mass conservation in the matrix gridblock; and
+|''p'' and ''q''&nbsp;&nbsp;&nbsp;&nbsp;||are fitting parameters that can be solved for by enforcing the diffusion differential equation at the interface and mass conservation in the matrix gridblock; and
 |-
-| ''d'' || is the concentration penetration depth, which is defined in the REMChlor-MD User’s Manual in Appendix 1.
+|''d''||is the concentration penetration depth, which is defined in the REMChlor-MD User’s Manual in Appendix 1.
 |}
@@ Line 53: / Line 57: @@
 There are three key geometrical model inputs to the semi-analytical method that can be used to model the diffusion process:
 *''V<sub>f</sub>'' is the volume fraction of the high-permeability materials in a gridblock;
 *''A<sub>md</sub>'' is the interfacial area between the high-K and low-K materials in a gridblock; and
@@ Line 61: / Line 66: @@
 ::'''Equation 2:'''&nbsp;&nbsp;&nbsp;&nbsp;<big>''A<sub>md</sub> L = (1 – V<sub>f</sub>) V''</big>
-This semi-analytical method has undergone thorough testing and proved to be accurate in numerous scenarios<ref name= "Falta2017"/><ref name= "Muskus2018">Muskus, N. and Falta, R.W., 2018. Semi-analytical method for matrix diffusion in heterogeneous and fractured systems with parent-daughter reactions. Journal of Contaminant Hydrology, 218, pp.94-109. [https://doi.org/10.1016/j.jconhyd.2018.10.002 doi: 10.1016/j.jconhyd.2018.10.002]</ref>.  The following section shows common test scenarios where the method can be used.
+This semi-analytical method has undergone thorough testing and proved to be accurate in numerous scenarios<ref name="Falta2017" /><ref name="Muskus2018">Muskus, N. and Falta, R.W., 2018. Semi-analytical method for matrix diffusion in heterogeneous and fractured systems with parent-daughter reactions. Journal of Contaminant Hydrology, 218, pp.94-109. [https://doi.org/10.1016/j.jconhyd.2018.10.002 doi: 10.1016/j.jconhyd.2018.10.002]</ref>.  The following section shows common test scenarios where the method can be used.
 [[File:Falta1w2 Fig3.png|thumb|left|Figure 3.  Concentration profiles in fractures at 1, 49, 51 and 100 years.]]
@@ Line 79: / Line 84: @@
 The match between the analytical solution and the semi-analytical method was good, particularly during the loading period. In the unloading period, the semi-analytical method overestimated the peak concentration somewhat, but it still captured the long tailing of concentration almost exactly.
-[[File:Falta1w2 Fig7.png|thumb|right|400px| link=https://www.enviro.wiki/images/c/c5/Falta1w2_Fig7.mp4 | [[Media:Falta1w2 Fig7.mp4 |Figure 7: Video tutorial demonstrating use of REMChlor-MD]]]]
+[[File:Falta1w2 Fig7.png|thumb|right|400px| link=https://www.enviro.wiki/images/c/c5/Falta1w2_Fig7.mp4 | [//www.enviro.wiki/images/c/c5/Falta1w2_Fig7.mp4 Figure 7: Video tutorial demonstrating use of REMChlor-MD]]]
 ===Matrix Diffusion in Heterogeneous Media===
-One of the motivations for REMChlor-MD was to develop an alternative to a computationally expensive fine grid model for simulating matrix diffusion.  To evaluate the ability of the semi-analytical method incorporated into REMChlor-MD to accurately simulate back-diffusion, a heterogeneous fine grid model was developed<ref name= "Muskus2018"/> using MT3DMS. A geostatistical model generated multiple realizations of the subsurface’s heterogeneity using synthetic borehole data.  Using the heterogeneous material distribution of sand and clay, a fine grid flow and transport model, consisting of almost 3 million gridblocks, was created. A TCE source was present near the upgradient end of the model for 30 years and then it was completely removed. Following source removal, clean water was flushed through the system for another 200 years.
+One of the motivations for REMChlor-MD was to develop an alternative to a computationally expensive fine grid model for simulating matrix diffusion.  To evaluate the ability of the semi-analytical method incorporated into REMChlor-MD to accurately simulate back-diffusion, a heterogeneous fine grid model was developed<ref name="Muskus2018" /> using MT3DMS. A geostatistical model generated multiple realizations of the subsurface’s heterogeneity using synthetic borehole data.  Using the heterogeneous material distribution of sand and clay, a fine grid flow and transport model, consisting of almost 3 million gridblocks, was created. A TCE source was present near the upgradient end of the model for 30 years and then it was completely removed. Following source removal, clean water was flushed through the system for another 200 years.
 For comparison, a REMChlor-MD model was developed with a much coarser grid (about 14,000 gridblocks) where flow and transport parameters were comparable to the fine grid model. The mass discharge at the outlet of the models was used as a comparison criterion between the two models.  Figure 4 shows a comparison of the computed mass discharge versus time at the downstream edge of the model.  The mass discharge predicted by the 3-million gridblock MT2DMS simulation is shown as the yellow dots.  The green line shows the REMChlor-MD prediction based on the geostatistical properties of the high and low K zones (characteristic maximum diffusion length, L= 1.85m).  The REMChlor-MD match to the fine-grid MT3DMS model was slightly improved by reducing the characteristic maximum diffusion length (L= 1.5m).  Both of these results are similar to the 3-million gridblock MT3DMS simulation result.
@@ Line 89: / Line 94: @@
 ==REMChlor-MD User Interface==
-The semi-analytical method was programmed in FORTRAN, and a graphical user interface (GUI) was built using Visual Basic in Excel® to facilitate data inputs and output processing<ref>Farhat, S. K., Newell, C. J., Falta, R. W., and Lynch, K. (2018). REMChlor-MD toolkit user’s manual. ER-201426 [[media:2018-Falta-REMChlor_Modeling_Matrix_Diffusion_Effects.pdf | Report.pdf]]</ref>.  The Visual Basic REMChlor-MD interface calls the FORTRAN executable using a dynamic link library, and then processes the FORTRAN output files to produce various graphs.  A short video tutorial demonstrating data entry and some of the capabilities of REMChlor-MD is shown in Figure 7.  Additional detail is provided in an online [https://www.serdp-estcp.org/Tools-and-Training/Webinar-Series/02-07-2019 webinar].  The toolkit package, including a user’s manual is available free of charge and can be downloaded here ([https://www.serdp-estcp.org/content/download/48566/462193/file/REMChlorMD_64bit.zip 64bit version]) and ([https://www.serdp-estcp.org/content/download/48565/462183/file/REMChlorMD_32bit.zip 32 bit version]).  Readers are referred to the [https://www.serdp-estcp.org/content/download/48433/460814/file/ER-201426%20REMChlor-MD%20User's%20Manual.pdf user manual] for a complete explanation of the program, its input parameters, outputs, and examples.
+The semi-analytical method was programmed in FORTRAN, and a graphical user interface (GUI) was built using Visual Basic in Excel® to facilitate data inputs and output processing<ref>Farhat, S. K., Newell, C. J., Falta, R. W., and Lynch, K. (2018). REMChlor-MD toolkit user’s manual. ER-201426 [//www.enviro.wiki/images/0/0b/2018-Falta-REMChlor_Modeling_Matrix_Diffusion_Effects.pdf  Report.pdf]</ref>.  The Visual Basic REMChlor-MD interface calls the FORTRAN executable using a dynamic link library, and then processes the FORTRAN output files to produce various graphs.  A short video tutorial demonstrating data entry and some of the capabilities of REMChlor-MD is shown in Figure 7.  Additional detail is provided in an online [https://www.serdp-estcp.org/Tools-and-Training/Webinar-Series/02-07-2019 webinar].  The toolkit package, including a user’s manual is available free of charge and can be downloaded here ([https://www.serdp-estcp.org/content/download/48566/462193/file/REMChlorMD_64bit.zip 64bit version]) and ([https://www.serdp-estcp.org/content/download/48565/462183/file/REMChlorMD_32bit.zip 32 bit version]).  Readers are referred to the [https://www.serdp-estcp.org/content/download/48433/460814/file/ER-201426%20REMChlor-MD%20User's%20Manual.pdf user manual] for a complete explanation of the program, its input parameters, outputs, and examples.

@@ Line 79: / Line 79: @@
 The match between the analytical solution and the semi-analytical method was good, particularly during the loading period. In the unloading period, the semi-analytical method overestimated the peak concentration somewhat, but it still captured the long tailing of concentration almost exactly.
-[[File:Falta1w2 Fig7.png|thumb|right|400px| link=https://www.enviro.wiki/index.php?title=File:Falta1w2_Fig7.mp4 | [[Media:Falta1w2 Fig7.mp4 |Figure 7: Video tutorial demonstrating use of REMChlor-MD]]]]
+[[File:Falta1w2 Fig7.png|thumb|right|400px| link=https://www.enviro.wiki/images/c/c5/Falta1w2_Fig7.mp4 | [[Media:Falta1w2 Fig7.mp4 |Figure 7: Video tutorial demonstrating use of REMChlor-MD]]]]
 ===Matrix Diffusion in Heterogeneous Media===

@@ Line 79: / Line 79: @@
 The match between the analytical solution and the semi-analytical method was good, particularly during the loading period. In the unloading period, the semi-analytical method overestimated the peak concentration somewhat, but it still captured the long tailing of concentration almost exactly.
-[[File:Falta1w2 Fig7.png|thumb|right|400px| link=https://www.enviro.wiki/index.php?title=File:Falta1w2_Fig7.png | [[Media:Falta1w2 Fig7.mp4 |Figure 7: Video tutorial demonstrating use of REMChlor-MD]]]]
+[[File:Falta1w2 Fig7.png|thumb|right|400px| link=https://www.enviro.wiki/index.php?title=File:Falta1w2_Fig7.mp4 | [[Media:Falta1w2 Fig7.mp4 |Figure 7: Video tutorial demonstrating use of REMChlor-MD]]]]
 ===Matrix Diffusion in Heterogeneous Media===

@@ Line 79: / Line 79: @@
 The match between the analytical solution and the semi-analytical method was good, particularly during the loading period. In the unloading period, the semi-analytical method overestimated the peak concentration somewhat, but it still captured the long tailing of concentration almost exactly.
-[[File:Falta1w2 Fig7.png|thumb|right|400px| link=https://www.enviro.wiki/Falta1w2_Fig7.mp4 | [[Media:Falta1w2 Fig7.mp4 |Figure 7: Video tutorial demonstrating use of REMChlor-MD]]]]
+[[File:Falta1w2 Fig7.png|thumb|right|400px| link=https://www.enviro.wiki/index.php?title=File:Falta1w2_Fig7.png | [[Media:Falta1w2 Fig7.mp4 |Figure 7: Video tutorial demonstrating use of REMChlor-MD]]]]
 ===Matrix Diffusion in Heterogeneous Media===

@@ Line 79: / Line 79: @@
 The match between the analytical solution and the semi-analytical method was good, particularly during the loading period. In the unloading period, the semi-analytical method overestimated the peak concentration somewhat, but it still captured the long tailing of concentration almost exactly.
-[[File:Falta1w2 Fig7.png|thumb|right|400px| link=Falta1w2 Fig7.mp4 | [[Media:Falta1w2 Fig7.mp4 |Figure 7: Video tutorial demonstrating use of REMChlor-MD]]]]
+[[File:Falta1w2 Fig7.png|thumb|right|400px| link=https://www.enviro.wiki/Falta1w2_Fig7.mp4 | [[Media:Falta1w2 Fig7.mp4 |Figure 7: Video tutorial demonstrating use of REMChlor-MD]]]]
 ===Matrix Diffusion in Heterogeneous Media===

@@ Line 16: / Line 16: @@
 ==Matrix Diffusion of Dissolved Contaminants==
 Dissolved contaminants, such as [[Chlorinated Solvents | chlorinated volatile organic compounds (CVOCs)]], are found in groundwater at many current and former industrial sites globally. Plumes of CVOCs dissolved in groundwater often originate when the chemicals enter the subsurface as dense non-aqueous phase liquids (DNAPL). Being heavier than water and immiscible, DNAPLs are particularly problematic because they can spread vertically into the aquifer, generating extensive contaminated groundwater plumes. In Figure 1, CVOCs in DNAPL form are shown in bold red, and the resulting dissolved groundwater plume is represented by the pink halo emanating from the DNAPLs. One of the most significant lessons learned about chlorinated solvents is that their groundwater plumes can persist even when the source DNAPLs have been depleted. Plume persistence in the absence of source materials has been attributed to a phenomenon called matrix diffusion.   Matrix diffusion can affect any type of dissolved contaminant, particularly when dissolved concentrations are high relative to regulatory standards.  In addition to CVOCs, matrix diffusion can occur with other dissolved contaminants including radionuclides, [[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) | per- and polyfluoroalkyl substances (PFAS)]], dissolved petroleum hydrocarbons such as benzene, toluene, ethylbenzene, and xylene (BTEX), and with solvent stabilizers such as [[1,4-Dioxane | 1,4-dioxane]].
 The life cycle of a matrix diffusion site is separated into two periods. In the loading period, the [[Characterization Methods – Hydraulic Conductivity | low-permeability (low K)]] zones act as storage areas for the contaminant mass. Following clean-up actions in the transmissive (high K) zones, the concentration gradient is reversed. The unloading period begins when the contaminant mass previously stored in the low-permeability zones diffuses back out into the transmissive zones. In Figure 1, the blue arrows represent the forward and backward diffusion gradients into the surrounding materials. Because the pace of back diffusion can be significantly slower than the loading of the contaminant, the plume resulting from the back diffusing mass can last for decades to centuries<ref>Chapman, S.W. and Parker, B.L., 2005. Plume persistence due to aquitard back diffusion following dense nonaqueous phase liquid source removal or isolation. Water Resources Research, 41(12). [https://doi.org/10.1029/2005WR004224 doi: 10.1029/2005WR004224]</ref><ref>Parker, B.L., Chapman, S.W. and Guilbeault, M.A., 2008. Plume persistence caused by back diffusion from thin clay layers in a sand aquifer following TCE source-zone hydraulic isolation. Journal of Contaminant Hydrology, 102(1-2), pp.86-104. [https://doi.org/10.1016/j.jconhyd.2008.07.003 doi: 10.1016/j.jconhyd.2008.07.003]</ref>.
@@ Line 24: / Line 24: @@
 ==Matrix Diffusion Modeling Options==
 There have been limited options available for simulating matrix diffusion effects at groundwater contamination sites. Available analytical models require simplifications that may overlook the unique complexities at actual remediation sites.  Numerical models are often used to simulate solute transport, but require fine discretization to capture matrix diffusion concentration gradients, which occur at millimeters to centimeters scale.  This very fine discretization (fine model grid) greatly increases the number of model cells required to simulate transport at field sites, greatly increasing computer model run times.  Figure 2 shows a typical fine grid model containing almost 3 million gridblocks (cells).
 Another type of numerical model of matrix diffusion is the dual-porosity model which is more computationally efficient because it uses a first order approximation to describe the mass transfer between the high K and low K zones. Dual-porosity models can be calibrated to match the effects of matrix diffusion on contaminant concentrations over short time periods.  However, the first order mass transfer coefficient is time-dependent<ref>Guan, J., Molz, F.J., Zhou, Q., Liu, H.H. and Zheng, C., 2008. Behavior of the mass transfer coefficient during the MADE‐2 experiment: New insights. Water Resources Research, 44(2). [https://doi.org/10.1029/2007WR006120 doi: 10.1029/2007WR006120]</ref>, so models calibrated to early time data will not accurately simulate concentrations at a later time.
@@ Line 64: / Line 64: @@
 [[File:Falta1w2 Fig3.png|thumb|left|Figure 3.  Concentration profiles in fractures at 1, 49, 51 and 100 years.]]
-[[File:Falta1w2 Fig4.png|thumb|left|Figure 4: Simulated mass discharge at downstream edge of fine-grid MT3DMS and REMChlor-MD models.]]
+[[File:Falta1w2 Fig4.png|thumb|right|Figure 4: Simulated mass discharge at downstream edge of fine-grid MT3DMS and REMChlor-MD models.]]
-[[File:Falta1w2 Fig5.png|thumb|right|Figure 5: Top view (''xy'') of concentration contours computed with the fine-grid numerical model (top) and with REMChlor-MD (bottom) at 30 years.]]
+[[File:Falta1w2 Fig5.png|thumb|left|Figure 5: Top view (''xy'') of concentration contours computed with the fine-grid numerical model (top) and with REMChlor-MD (bottom) at 30 years.]]
 [[File:Falta1w2 Fig6.png|thumb|right|Figure 6: Top view (''xy'') of concentration contours computed with the fine-grid numerical model (top) and with REMChlor-MD (bottom) at 130 years.]]
@@ Line 79: / Line 79: @@
 The match between the analytical solution and the semi-analytical method was good, particularly during the loading period. In the unloading period, the semi-analytical method overestimated the peak concentration somewhat, but it still captured the long tailing of concentration almost exactly.
-[[File:Falta1w2 Fig7.mp4|thumb|left|Figure 7: Video tutorial demonstrating use of REMChlor-MD]]
+[[File:Falta1w2 Fig7.mp4|thumb|right|400px|Figure 7: Video tutorial demonstrating use of REMChlor-MD]]
 ===Matrix Diffusion in Heterogeneous Media===

@@ Line 34: / Line 34: @@
 REMChlor-MD employs a semi-analytical method adapted from a heat diffusivity estimation strategy used in petroleum engineering and applied here to the problem of chemical diffusion with first order decay kinetics<ref>Vinsome, P.K.W. and Westerveld, J., 1980. A simple method for predicting cap and base rock heat losses in'thermal reservoir simulators. Journal of Canadian Petroleum Technology, 19(03).  Pp 87-90 [https://doi.org/10.2118/80-03-04 doi: 10.2118/80-03-04]</ref><ref name= "Falta2017">Falta, R.W. and Wang, W., 2017. A semi-analytical method for simulating matrix diffusion in numerical transport models. Journal of contaminant hydrology, 197, pp.39-49. [https://doi.org/10.1016/j.jconhyd.2016.12.007 doi: 10.1016/j.jconhyd.2016.12.007]</ref>.  This semi-analytical method utilizes a fitting function to describe the concentration of the chemical in the low K zones in, or adjacent to, each gridblock:
-::'''Equation 1:'''&nbsp;&nbsp;&nbsp;&nbsp;<big>''C<sub>l</sub>(z<sub>l</sub>,t) = (C</big><sup>t + &Delta;t</sup><big> + pz<sub>l</sub> + qz<sub>l</sub><sup>2</sup>) e</big><sup>-z<sub>l</sub> / d''
+::'''Equation 1:'''&nbsp;&nbsp;&nbsp;&nbsp;<big>''C<sub>l</sub></big>(z<sub>l</sub>,t)<big> = (C</big><sup>t + &Delta;t</sup><big> + pz<sub>l</sub> + qz<sub>l</sub><sup>2</sup>) e</big><sup>-z<sub>l</sub> / d''
 {|
 |-