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Cimarron Environmental Response Trust Facility Decommissioning Plan, Revision 2, Appendix L, 2020 Groundwater Flow Model, Part 1
ML21076A457
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Site: 07000925
Issue date: 02/26/2021
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Environmental Properties Management, Enercon Services, Burns & McDonnell Engineering Co, Veolia Nuclear Solutions Federal Services
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Office of Nuclear Material Safety and Safeguards, Cimarron Environmental Response Trust, NRC Region 4
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BURNS ~ SDONNELL 2020 Groundwater Flow Model Review Cimarron Remediation Site Cimarron Environmental Response Trust Project No. 120832 Revision 0 2/24/2020

2020 Groundwater Flow Model Review Cimarron Remediation Site Prepared for Cimarron Environmental Response Trust Crescent, Oklahoma Project No. 120832 Revision 0 2/24/2020 Prepared by Burns & McDonnell Engineering Company, Inc.

Kansas City, Missouri

TABLE OF CONTENTS Page No.

1.0 INTRODUCTION

.................................................................................................. 1 2.0 DATA REVIEW .................................................................................................... 1 2.1 Vertical Distribution Data Evaluation ..................................................................... 1 3.0 MODEL CONSTRUCTION ................................................................................... 1 3.1 Model Code and Processing Software ..................................................................... 1 3.2 Impact of Partial Penetration on Well Capture ........................................................ 1 3.3 Modifications to the Existing (2016) Models .......................................................... 2 3.3 .1 Model Layering WAA Model.. ................................................................. 2 3.3.2 Model Layering BAI Mode ...................................................................... 3 3.3.3 MNW2 Well Package ...............................................................................3 3.3 .4 Well Screen Intervals ........................................................ ....................... .4 3.4 Particle Tracking Simulations .................................................................................. 4 4.0 PARTICLE TRACKING RESULTS ...................................................................... 1 4.1 Nominal Pumping Scenarios .................................................................................... I 4.1.1 WAA Particle Tracking - Nominal Rates ................................................ 1 4.1.2 BAI Particle Tracking - Nominal Rates .................................................. 1 4.2 Alternate Pumping Scenarios ................................................................................... I 5.0

SUMMARY

AND CONCLUSIONS ....................................................................... 1

6.0 REFERENCES

..................................................................................................... 1 APPENDIX A - 2016 GROUNDWATER FLOW MODEL UPDATE APPENDIX B - VERTICAL DISTRIBUTION OF URANIUM IN GROUNDWATER CROSS SECTIONS APPENDIX C - SELECT FIGURES FROM THE 2018 CIMARRON FACILITY DECOMMISSIONING PLAN, REVISION 1 CIMARRON ENVIRONMENTAL RESPONSE TRUST Burns & McDonnell

LIST OF FIGURES 4-1 Nominal Pumping Scenario Particle Tracking Comparison in the WAA 4-2 Nominal Pumping Scenario Particle Tracking Comparison in BA 1 4-3 W AA U>DCGL Alternate Pumping Scenarios Particle Tracking 4-4 BA 1-B Alternate Pumping Scenarios Particle Tracking 4-5 W AA Nominal Pumping Scenario Particle Tracking 4-5 W AA Alternate Pumping Scenario l Particle Tracking 4-7 W AA Alternate Pumping Scenario 2 Particle Tracking CIMARRON ENVIRONMENTAL RESPONSE TRUST ii Burns & McDonnell

LIST OF ABBREVIATIONS Abbreviation Term/Phrase/Name BAI Burial Area # 1 BAl-B Subarea B of Burial Area # 1 Burns & McDonnell Burns & McDonnell Engineering Company, Inc.

EC Electrical Conductivity EPM Environmental Properties Management LLC Ft/day Feet per Day GPM Gallon per Minute HPT Hydraulic Profiling Tool K Hydraulic Conductivity MNW2 MODFLOW Multi-Node Well package Site Cimarron Site Trust Cimarron Environmental Response Trust U>DCGL Uranium Greater Than the DCGL Area VDU Vertical Distribution of Uranium WAA Western Alluvial Area WU Western Uplands Area CIMARRON ENVIRONMENTAL RESPONSE TRUST iii Burns & McDonnell

2020 Groundwater Flow Model Update Revision 0 Introduction

1.0 INTRODUCTION

On behalf of Environmental Property Management LLC (EPM), Trustee for the Cimarron Environmental Response Trust (Trust), Bums & McDonnell Engineering Company, Inc. (Bums & McDonnell) submits this 2020 Groundwater Flow Model Review report for the Cimarron site (the Site), located at 100 N. Highway 74, Guthrie, Oklahoma. During this review two existing groundwater flow models were updated to further evaluate groundwater remediation alternatives at two areas on the Site. The areas include Burial Area #1 (BAI) and the Western Alluvial Area (WAA). The groundwater models were originally developed as part of the Groundwater Flow Modeling Report (ENSR, 2006), and updated in the Groundwater Flow Model Update (Burns & McDonnell, 2014) and the 2016 Groundwater Flow Model Update (Bums & McDonnell, 2017a). The 2006 and 2014 reports are included with the 2016 report which is attached as Appendix A in this report.

The models were updated to evaluate a hypothetical alternative remediation scenario that included use of partially penetrating extraction wells, alternate pumping rates at select wells, and refinement of the alluvial aquifer model layer parameters. Partially penetrating wells were used to represent extraction wells with shorter screen lengths that would focus groundwater extraction in portions of the aquifer with the highest uranium levels. Variable pumping rates utilized in a previous stagnation zone analysis for extraction wells within the WAA U>DCGL and Subarea B of Burial Area #1 (BAI-B) remediation areas were utilized to show no significant changes to flow occurred in areas where stagnation was a potential concern. Refinement of the alluvial aquifer model layer parameters was completed to represent the fining upward grainsize distribution observed within the alluvial aquifer at the Site. The updated groundwater models were linked to a particle tracking model (MODPA TH) to evaluate the hypothetical alternative remediation scenarios for groundwater extraction using both groundwater recovery trenches and extraction wells. These modeling results were then compared to modeling results presented in the Cimarron Facility Decommissioning Plan, Revision l (EPM, 2018) to evaluate relative differences in groundwater flow conditions between the models under nominal and alternate pumping conditions.

CIMARRON ENVIRONMENTAL RESPONSE TRUST 1-1 Burns & McDonnell

2020 Groundwater Flow Model Update Revision 0 Data Review 2.0 DATA REVIEW The objective of the data review was to evaluate existing data to aid the refinement of groundwater model layers representing the alluvial aquifer in BA 1 and WAA. Two primary datasets used during the review included the monitor well boring logs and the vertical profiling data presented in the Vertical Distribution of Uranium in Groundwater (VDU) report (Bums & McDonnell, 2017). Figures 2-2, 2-3, and 3-2 form this report are included as Appendix B.

2.1 Vertical Distribution Data Evaluation Cross sections from the VDU report containing Hydraulic Profiling Tool (HPT), Electrical Conductivity (EC), and uranium concentration data for the BA 1 and W AA were reviewed to identify possible correlations between these data and existing boring log lithology data from monitor wells adjacent to the VDU investigation borings. The monitor well boring logs were prepared based on observations of soil cuttings collected at the surface from hollow stem auger flights. Logging of soil cuttings from auger flights does not preserve the native characteristics of soil samples collected using continuous coring methods such as direct-push or sonic drilling. This can especially be true when drilling in relatively non-cohesive sandy zones under hydrostatic pressure that generate "flowing sand" conditions as were encountered during drilling and installation of monitor wells in the alluvial aquifer at the Site. No additional boring logs with lithologic data were generated during the December 2016 VDU investigation because the borings were completed within approximately 10 feet of existing monitor wells and no soil samples were collected during the advancement of the HPT/EC probes. Boring logs were overlaid with the HPT, EC, and uranium concentration data from the vertical distribution of uranium cross sections to better assess the existing lithologic descriptions (Appendix C).

The HPT and EC data for BA 1 and W AA did not show consistent correlation when compared to the lithology descriptions on the monitor well boring logs. The observed HPT and EC responses were generally consistent with each other. Higher EC values and corresponding higher HPT pressures representative of lower permeability, finer grained lithologic layers were observed together while lower EC values and corresponding lower HPT pressures representative of higher permeability, coarser grained lithologic layers were also observed together. A review of uranium concentration data also showed generally consistent correlation between higher permeable zones (i.e., lower EC values and lower HPT pressures) and higher uranium concentrations. The boring log, HPT, and EC data did not show consistent correlation across multiple borings suggesting that individual lithologic layers were not continuous over large portions of BA 1 and WAA. The observed discontinuous nature of the lithologic layers is expected for sediments deposited in an active tluvial environment where there is continuous lateral and vertical CIMARRON ENVIRONMENTAL RESPONSE TRUST 2-1 Burns & McDonnell

2020 Groundwater Flow Model Update Revision 0 Data Review erosion and deposition. The vertical uranium concentration data profile was also compared with boring log lithology data and no consistent correlation was observed.

Review of the December 2016 VDU data and boring logs indicated changes in lithology were not consistent between borings at similar depth or elevation intervals. Following this review, model layers representing the BA 1 and W AA alluvial aquifer were modified to increase the vertical resolution of the model. Additional details regarding the changes to the model layers for BA 1 and the W AA are described in Section 3.3 below.

CIMARRON ENVIRONMENTAL RESPONSE TRUST 2-2 Burns & McDonnell

2020 Groundwater Flow Model Update Revision 0 Model Construction 3.0 MODEL CONSTRUCTION The primary modifications to the existing groundwater models for the simulation of partial penetrating wells in a fining upward alluvial aquifer were to add additional alluvial aquifer model layers, adjust the hydraulic conductivity (K) distribution for the alluvial aquifer model layers, and use the MODFLOW Multi-Node Well (MNW2) package to simulate well pumping through short screen intervals. No other changes were made to existing groundwater models. The following sections describe the model update.

3.1 Model Code and Processing Software Consistent with previous iterations of the CERT groundwater models, MODFLOW-2000 (Harbaugh et al., 2000), a three-dimensional, finite difference groundwater flow computer code, was selected to update the groundwater models. Model construction and the evaluation of model-predicted output were completed using Groundwater Vistas Version 7. Groundwater Vistas is a pre- and post-processing software package that was used to create standard format MODFLOW file sets from graphically input data. Model output was evaluated using Groundwater Vistas, Surfer Version 15 (Golden Software),

ArcMap 10 (ESRI) and Microsoft Office programs. Groundwater Vistas was used when possible to provide contoured model-predicted results (model predicted heads and drawdown) and numerical data output. Additional data contouring and evaluation was completed using Surfer. Surfer is a grid-based contouring and three-dimensional surface plotting program. Surfer and Arc Map 10 were used to interpolate the irregularly spaced, model-predicted data onto regularly spaced grids and to produce contoured results.

3.2 Impact of Partial Penetration on Well Capture A partially penetrating well that is only open to a fraction of the full saturated thickness of an aquifer creates a vertical flow component that causes additional drawdown in the well beyond the drawdown that would be calculated assuming horizontal flow for a fully penetrating well. This concept is widely recognized and well documented. For example, in Chapter 10 of Analysis and Evaluation of Pumping Test Data (Kruseman and de Ridder, 1990) the authors note that: "Partial penetration causes the flow velocity in the immediate vicinity of the well to be higher than it would be otherwise, leading to an extra loss of head (drawdown). This effect is strongest at the well face and decreases with increasing distance from the well. It is negligible if measured at a distance that is 1.5 to 2 times greater than the saturated thickness of the aquifer, depending on the amount of penetration."

Analysis of the impact of partial penetration on the capture zones of wells has also been performed by various researchers. In Hydrodynamics of the Capture Zone of a Partially Penetrating Well in a Confined CIMARRON ENVIRONMENTAL RESPONSE TRUST 3-1 Burns & McDonnell

2020 Groundwater Flow Model Update Revision 0 Model Construction Aquifer (Faybishenko, et.al, 1995), the authors noted that "The results have shown that with a constant pumping rate the maximum horizontal extent of the capture surface at the top of the aquifer increases as the degree of penetration decreases. As one would expect, the maximum vertical extent increases as the depth of penetration increases."

At both the BA 1 and WAA, the extraction wells will be screened at the lower portion of the of the alluvial aquifer. As summarized above, using 10-foot well screens and locating the screens in the lower portion of the alluvial deposits maximizes both the vertical and horizontal capture zones of the extraction wells.

3.3 Modifications to the Existing (2016) Models The vertical profiling evaluation discussed in Section 2 did not identify geologic units within the alluvial aquifer that are laterally continuous across BA 1 or WAA. For this reason, changes to the existing model layers was limited to subdividing existing layers to increase vertical resolution (i.e., decreasing vertical thickness of cells and increasing the number of cells) and varying the hydraulic conductivity in the newly subdivided alluvial aquifer layers to reflect the observed fining upward sequence of the unconsolidated materials in the alluvial aquifer at the Site. The following section summarizes the changes made within the two models.

3.3.1 Model Layering WAA Model The 2016 groundwater model simulated the alluvial materials in the WAA model domain as one model layer, which is approximately 20 feet thick in most of the model domain. To increase the vertical resolution, and to better approximate the fining upward sequence of unconsolidated deposits, the alluvial model layer was split into two layers. The existing model layer was split equally to create two layers that represent the alluvial aquifer in the WAA. In the 2016 groundwater model, the alluvial deposits were simulated as a single layer with a hydraulic conductivity (K) of 235 feet per day (ft/day) and an anisotropy ratio of 10: I (Kxy: Kz). In the updated W AA model, the alluvial aquifer is simulated as two layers, with the following hydraulic conductivity values:

  • New upper alluvial aquifer model layer 1; K of 117.5 ft/day.
  • New lower alluvial aquifer model layer 2; K of352.5 ft/day.

Since the model layer was divided equally, the Kin the upper model layer was set equal to 50% of the 2016 modeled value and the Kin the lower alluvial model layer was set equal to 150% of the 2016 model.

This results in a total aquifer transmissivity for the alluvial aquifer that was unchanged from the 2016 groundwater model. The anisotropy ratio in the updated groundwater model was unchanged and remained at 10:1.

CIMARRON ENVIRONMENTAL RESPONSE TRUST 3-2 Burns & McDonnell

2020 Groundwater Flow Model Update Revision 0 Model Construction 3.3.2 Model Layering BA1 Mode Twelve layers are used to simulate the geology of the BA 1 area. The upper eight model layers are used to simulate the alluvial aquifer, which is approximately 20 feet thick in most of the model domain, and the lower four layers simulate bedrock layers with lower permeability. The model layers are generally uniform with individual layer thicknesses typically between two and three feet. No adjustments were made to the number of layers or the layer elevations for BA 1 during this model update. The original model layering system setup was described in the 2006 Groundwater Flow Modeling Report (ENSR, 2006) and was not modified during this model update.

In the 2016 groundwater model, the alluvial deposits were simulated with a K of235 feet per day (ft/day) for model layers one 1 through model layer 8. An anisotropy ratio of 10: 1 (Kxy: Kz) was used to simulate flow in the alluvial deposits. In the updated BA 1 model, the alluvial aquifer is simulated as follows:

  • Upper alluvial aquifer model layer 1 through 4; K of 117.5 ft/day.
  • Lower alluvial aquifer model layer 5 through 8; K of 352.5 ft/day.

As in the W AA model, the hydraulic conductivity of the alluvial aquifer was redistributed to reflect the observed fining upward sequence, while maintaining the same total aquifer transmissivity as used in previous modeling efforts. The anisotropy ratio in the updated groundwater model was unchanged and remained at 10: l.

3.3.3 MNW2 Well Package In previous versions of the groundwater flow models, pumping wells were simulated using the original MODFLOW well package, which simulates the prescribed flow rate of a well as being extracted across the entire vertical thickness of a model cell (i.e., fully penetrating well screen). A significant change from the previous groundwater flow models is how pumping wells were simulated in this updated version of the models.

The updated groundwater models simulate extraction wells using discrete, short screen intervals, using the Multi-Node Well (MNW2) Package (Konikow, et. al. 2009). In the MNW2 Package, a single well screen can occur at any position within a model layer if the user specifies the elevation of the top and bottom of the well screen. The MNW2 package uses the specified top and bottom of the screen intervals to distribute the prescribed well pumping rate within the cell and to calculate the additional head loss in the pumping well that occurs due to partial penetration effects. The original MODFLOW well package used in previous versions of the CERT groundwater models did not consider well construction details, like the screen interval length, in distributing the prescribed flow within the model.

CIMARRON ENVIRONMENTAL RESPONSE TRUST 3-3 Burns & McDonnell

2020 Groundwater Flow Model Update Revision 0 Model Construction 3.3.4 Well Screen Intervals All extraction wells simulated in the BA 1 or W AA models were simulated with ten-foot long screen intervals. The bottom of the screen interval was set immediately above the bottom of the model cell that the extraction well is located in. For example, if an extraction well in the BA 1 model was previously screened in model layer 7, the bottom of the MNW2 extraction well screen was set equal to base of that layer 7 model cell. The extraction well screen intervals in the updated BA 1 model were all located within the lower layers 5 through 8. In the W AA model, the wells are all located in the lower alluvial layer (model layer 2).

3.4 Particle Tracking Simulations The particle tracking code MODPA TH (Pollock, 1989) was selected to perform the particle tracking analysis for both the BA 1 and W AA models. MOD PATH uses a semi-analytical particle tracking scheme and assumes that each directional velocity component for a particle of water varies linearly within a grid cell in its own coordinate direction (Pollock, 1989). This assumption allows an analytical expression to be derived that describes the flow path of water within a grid cell. Given the initial position of a particle anywhere in a cell, the pathline and travel time within the cell can be computed directly. Groundwater heads and intercell flow rates are first determined using MODFLOW.

Nominal and alternate flow rates for the extraction wells from the 2018 stagnation zone analysis were utilized for the particle tracking simulations. Flow rates for injection/extraction trenches were unchanged from the update of the groundwater flow model that was included in the 2018 Cimarron Facility Decommissioning Plan, Revision 1 (EPM, 2018). Forward particle tracking simulations were performed to evaluate remedial system performance. These particles were placed in each cell representing an injection trench and around specific areas of higher contaminant concentration that require containment.

These particles were then tracked forward using the MODP ATH code. Particles were placed in the middle of a model cell and tracked forward. The results of the forward particle tracking model simulations are presented on Figures (W AA) and Figure 2 (BA l ). All simulations show plume capture for the contaminants of concern. A comparison between these updated particle tracking figures and the particle tracking analysis developed with the previous version of the model is described in section 4.0 below. Particle starting locations were not changed from those presented in the 2018 Cimarron Facility Decommissioning Plan, Revision 1 (EPM, 2018).

CIMARRON ENVIRONMENTAL RESPONSE TRUST 3-4 Burns & McDonnell

2020 Groundwater Flow Model Update Revision 0 Particle Tracking Results 4.0 PARTICLE TRACKING RESULTS For this groundwater model update, particle tracking was completed under three pumping scenarios

( nominal, alternate 1, and alternate 2) for the W AA and BA 1. The results of the updated particle tracking were then compared to particle tracking results presented in the 2018 Cimarron Decommissioning Plan, Revision 1 (EPM, 2018). The extraction well pumping rates used for each of the pumping scenarios were the same as those presented in the 2018 Cimarron Decommissioning Plan, Revision 1 (EPM, 2018).

4.1 Nomi-nal Pumping Scenarios Sections 4.1.1 and 4.1.2 discuss the comparison of the 2018 Cimarron Decommissioning Plan, Revision 1 (EPM, 2018) and updated groundwater model review particle tracking results for the nominal pumping scenario. Figure 4-1 and 4-2 show both prior and updated particle tracking results for WAA and BA 1, respectively.

4.1.1 WAA Particle Tracking - Nominal Rates The updated nominal pumping rate particle tracking results in W AA show small increases in particle tracking pathline coverage (i.e., groundwater capture area) for several wells as compared to the prior model results. These wells include GE-WAA-06, GE-WAA-07, GE-WAA-08, GE-WAA-10, and GE-W AA-12. Particle tracking elsewhere in the WA area showed little change in coverage and predominantly overlapped with the prior particle tracking results. There was no decrease in particle tracking pathline coverage in the updated model.

4.1.2 BA 1 Particle Tracking - Nominal Rates No noteworthy changes were apparent in the comparison of the updated nominal pumping scenario particle tracking to prior particle tracking results in BA 1. There were only minor changes to particle tracking coverage.

4.2 Alternate Pumping Scenarios Figures 4-3 and 4-4 show the particle tracking for the wells in the WAA U>DCGL and BA 1-B areas that had alternate pumping rates. A comparison of Figure 4-3 to Figure 8-5 from the 2018 Cimarron Decommissioning Plan, Revision 1 (EPM, 2018) provided in Appendix C shows no noteworthy differences. Similarly, a comparison of Figure 4-4 to Figure 8-4 from the 2018 Cimarron Decommissioning Plan, Revision 1 (EPM, 2018) provided in Appendix C shows no noteworthy differences. Figures 4-5, 4-6, and 4-7 show particle tracking for the WAA for the nominal, alternate 1, and alternate 2 pumping scenarios, respectively. A review of these figures shows that particle tracking CIMARRON ENVIRONMENTAL RESPONSE TRUST 4-1 Burns & McDonnell

2020 Groundwater Flow Model Update Revision 0 Particle Tracking Results results for wells with no change in pumping rates (i.e., wells beyond WAA U>DCGL) are consistent and that the extraction system would capture groundwater from the remediation areas for each of the pumping scenarios. Because the updated 2020 particle tracking results were very similar to the 2018 particle tracking results, the results of the stagnation zone particle tracking analysis performed in 2018 was also expected to be very similar and was not repeated using the updated groundwater model.

CIMARRON ENVIRONMENTAL RESPONSE TRUST 4-2 Burns & McDonnell

2020 Groundwater Flow Model Update Revision 0 Summary and Conclusions 5.0

SUMMARY

AND CONCLUSIONS The objective of this report was to summarize the review of existing vertical distribution and lithologic data and updates to the alluvial aquifer layers in the groundwater models developed for BA l and the WAA at the Site. The updated models were then used to simulate the use of partially penetrating wells and the fining upward grain size distribution observed in the alluvial aquifer at the Site. The updated modeling results were then compared to prior modeling results representing nominal and alternate pumping scenarios during extraction of groundwater using fully penetrating extraction wells.

Evaluation of the December 2016 VDU data and boring logs showed a general correlation between changes in vertical profiling data (HPT, EC, and uranium concentrations) and changes in lithology in individual borings but limited correlation across multiple borings suggesting that individual lithologic layers were not continuous over large portions of BA 1 and the WAA. With little lithologic evidence to support to discrete changes to existing model layers, changes were made to the model to increase the vertical resolution of the models. The prior W AA alluvial aquifer model layer was divided into two layers and then the K values associated with BA 1 and W AA alluvial aquifer were updated to reflect a fining upward grain size distribution as described below.

Layers comprising the BA l alluvial aquifer in the model were divided into two groups with the upper layers l through 4 in one group and the lower layers 5 through 8 in the other group. The K values assigned to layers I through 4 were set equal to 50% of the K value from the 2016 model (upper unit) and K values for layers 5 through 8 were set to equal to 150% of the K value from the 2016 model (lower unit). For the WA area, the existing layer was divided in two (an upper and lower unit) and each was given new hydraulic conductivity (K) values. These groups were assigned K values in the same manner as the BA I area layers, with the upper unit having K values lower than the lower unit.

Particle tracking was completed using the updated models for three pumping scenarios: nominal, alternate scenario 1, and alternate scenario 2. Particle tracking results from the updated models was then compared with the 2018 Cimarron Decommissioning Plan, Revision 1 (EPM, 2018) particle tracking results. The comparison of the particle tracking results for the WAA showed a minor increase in particle tracking coverage when compared to the prior model particle tracking results especially in the area of several bluff wells. This comparison suggests that the changes to the updated model did not result in a decrease in groundwater captured by the extraction system and may result in improvements in groundwater capture at some bluff extraction wells. The updated model particle tracking results for BA 1 also showed only slight CIMARRON ENVIRONMENTAL RESPONSE TRUST 5-1 Burns & McDonnell

2020 Groundwater Flow Model Update Revision 0 Summary and Conclusions differences compared to the prior model results suggesting that the changes in the updated model did not result in a decrease in groundwater captured by the extraction system in BA 1. The nominal and alternate pumping scenarios for the updated groundwater model were reviewed and changes to the particle tracking pathways between the three pumping scenarios were very similar to the changes in particle tracking pathways observed in the 2018 stagnation zone analysis.

Overall, review of results from the updated groundwater model indicates that differentiating layers within the alluvial aquifer and shortening of well screens had no adverse impact on groundwater recovery by extraction wells within the alluvial aquifer. The modeling results confirm that the approach described in Section 8.2.1 of the 2018 Cimarron Decommissioning Plan, Revision 1 (EPM, 2018) to maximize the mass of contaminant removed while minimizing both the recovery and treatment of uncontaminated groundwater and the time required to achieve remediation goals by selecting extraction well screen intervals that span the zone of highest concentration, while also encompassing the saturated interval in which uranium concentrations exceed the MCL is acceptable and requires no modification.

CIMARRON ENVIRONMENTAL RESPONSE TRUST 5-2 Burns & McDonnell

2020 Groundwater Flow Model Update Revision 0 References

6.0 REFERENCES

Burns and McDonnell, 2014. Groundwater Flow Model Update, Cimarron Remediation Site. January.

Burns and McDonnell, 2017a. 2016 Groundwater Flow Model Update, Cimarron Remediation Site.

January 25.

Burns and McDonnell, 2017b. Vertical Distribution of Uranium in Groundwater. May 10.

Driscoll, F.G. 1986. Groundwater and Wells Second Edition. Johnson Filtration Systems Inc., St. Paul Minnesota.

Faybishenko, B.A., Javandel, I. and Witherspoon, P.A. 1995. Hydrodynamics of the Capture Zone of a Partially Penetrating Well in a Confined Aquifer. Water Resources Research. Volume 31, Issue 4.

April.

ENSR, 2006, Groundwater Flow Modeling Report. October.

Environmental Properties Management, LLC, 2018. Cimarron Facility Decommissioning Plan, Revision

1. October.

Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 2000. The U.S. Geological Survey Modular Ground-Water Model - User Guide to Modularization Concepts and the Groundwater Flow Process. U.S. Geological Survey Open-File Report 00-92.

Konikow, L.F., Hornberger, G.Z., Halford, K.J., and Hanson, R.T., 2009, Revised multi-node well (MNW2) package for MODFLOW ground-water flow model: U.S. Geological Survey Techniques and Methods 6-A30, Kruseman, G.P., and de Ridder, N.A. 1994. Analysis and Evaluation of Pumping Test Data. International Institute for Land Reclamation and Improvement. The Netherlands.

Pollock, D.W., 1989. Documentation of a computer program to compute and display pathlines using results from the U.S. Geological Survey modular three-dimensional finite-difference ground-water flow model. U.S. Geological Survey, Open File Report 94-464.

CIMARRON ENVIRONMENTAL RESPONSE TRUST 6-1 Burns & McDonnell

FIGURES FIGURE 4-1 NOMINAL PUMPING SCENARIO PARTICLE TRACKING COMPARISON IN THE WAA 2020 GROUNDWATER FLOW MODEL REVIEW CIMARRON SITE, OKLAHOMA

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+ MONITOR WELL IN SANDSTONE B

+ MONITOR WELL IN SANDSTONE C

+ PROPOSED MONITOR WELL IN ALLUVIUM 0 EXTRACTION WELLS e INJECTION WELLS PUMPING SCENARIO 2 FORWARD PARTICLE TRACKI NG PUMPING SCENARIO 1 FORWARD PARTICLE TRACKING NOMINAL PUMPING SCENARIO FORWARD PARTICLE TRACKING NOTES

1) PARTICLE TRACKING ARROWS DENOTE 60 DAY INTERVAL.
2) PARTICLE TRACKING RESULTS WERE DEVELOPED USING MODEL SETTlNGS DESCRIBED IN THE 2020 GROUNDWATER MODEL REVIEW: Burns and McDonnell, 2020. 2020 Groundwater Flow Model Update, Cimarron Remediation Site. January 25.

0 75 150 SCALE IN FEET

FIGURE 4-5 WM NOMINAL PUMPING SCENARIO PARTICLE TRACKING 2020 GROUNDWATER FLOW MODEL REVIEW CIMARRON SITE, OKLAHOMA

~ BURNS

'-'- MSDONNELL ~

environmental C.Pf lE AtlA-,t,cG O!OfP.rlH!S marir.nP.me!l! tC MONITOR WELL IN ALLUVIUM

+ MONITOR WELL IN SANDSTONE A

+ MONITOR WELL IN SANDSTONE B

+ MONITOR WELL IN SANDSTONE C

+ MONITOR WELL IN TRANSITION ZONE

+ PROPOSED MONITOR WELL IN ALLUVIUM 0 EXTRACTION WELLS e INJECTION WELLS EXTRACTION TRENCH

- INJECTION TRENCH NOMINAL PUMPING SCENARIO FORWARD

- -PARTICLE TRACKING WM-BLUFF WM-EAST WM-WEST l wMU>DCGL WU-UP1 WU-1348

=

L WU-UP2-SSA WU-UP2-SSB NOTES

1) PARTICLE TRACKING ARROWS DENOTE 60 DAY INTERVAL.
2) PARTICLI:: 1RACKING RESULTS WERE DEVELOPED USING MODEL SETTINGS DESCRIBED IN THE 2020 GROUNDWATER MODEL REVIEW: Bums and McDonnell, 2020. 2020 Groundwater Flow Model Update, Cimarron Remediation Site. January 25.

N 0

$ 300 600 SCALE IN FEET NAO 198 2011 StateP/ane Oklahoma orth FfPS 3501 Ft US

FIGURE 4-6 WAA ALTERNATE PUMPING SCENARIO 1 PARTICLE TRACKING 2020 GROUNDWATER FLOW MODEL REVIEW CIMARRON SITE, OKLAHOMA

~ BURNS

'-'-M£DON NELL ~

environmenta l CREAlF td"-1A""' l hG pmpP.rtiesnar;agememLtC MONITOR WELL IN ALLUVIUM

-+ MONITOR WELL IN SANDSTONE A

-+ MONITOR WELL IN SANDSTONE B

+ MONITOR WELL IN SANDSTONE C

-+ MONITOR WELL IN TRANSITION ZONE

-+ PROPOSED MONITOR WELL IN ALLUVIUM 0 EXTRACTION WELLS e INJECTION WELLS EXTRACTION TRENCH INJECTION TRENCH PUMPING SCENARIO 1 FORWARD PARTICLE TRACKING WAA-BLUFF WAA-EAST WAA-WEST WAAU>DCGL 1206-NORTH WU-PBA WU- UP1 WU-1348 r--

L__jWU-UP 2-SSA L WU-UP2-SSB NOTES

1) PARTICLE TRACKING ARROWS DENOTE 60 DAY INTERVAL.
2) PARTICLE TRACKING RESULTS WERE DEVELOPED USING MODEL SETTINGS DESCRIBED IN THE 2020 GROUNDWATER MODEL REVIEW: Burns and McDonnell, 2020. 2020 Groundwater Flow Model Update, Cimarron Remediation Site. January 25.

0 300 600 SCALE IN FEET AD 1983 2011 StateP/ane Oklahoma North FIPS 3501 Ft US

FIGURE 4-7 WAA ALTERNATE PUMPING SCENARIO 2 PARTICLE TRACKING 2020 GROUNDWATER FLOW MODEL REVIEW CIMARRON SITE, OKLAHOMA

~

environmental prooerties manaQement JC MONITOR WELL IN ALLUVIUM

+ MONITOR WELL IN SANDSTONE A

+ MONITOR WELL IN SANDSTONE B

+ MONITOR WELL IN SANDSTONE C

+ MONITOR WELL IN TRANS ITION ZONE

+ PROPOSED MONITOR WELL IN ALLUVIUM 0 EXTRACTION WELLS INJECTION WELLS EXTRACTION TRENCH

- INJECTION TRENCH PUMPING SCENARIO 2 FORWARD PART ICLE

- -TRACKING ARROWS WM-BLUFF WAA-EAST WAA-WEST WAAU>DCGL 1206-NORTH WU-PBA WU-UP1 WU -1 348 r -

L _ _ WU-UP2-SSA c- WU-UP2-SSB NOTES

1) PARTICLE TRACKING ARROWS DENOTE 60 DAY INTERVAL.
2) PARTICLE TRACKING RESULTS WERE DEVELOPED USING MODEL SETTINGS DESCRIBED IN THE 2020 GROUNDWATER MODEL REVIEW: Burns and McDonnell, 2020. 2020 Groundwater Flow Model Update, Cimarron Remediation Site. January 25.

0 300 600 SCALE IN FEET N D 1983 2011 StateP/an O lahoma North FIPS 3501 F US