ML24017A055

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Cimarron Environmental Response Trust Burial Area 1 Redox Evaluation Report
ML24017A055
Person / Time
Site: 07000925
Issue date: 01/17/2024
From: Lux J
Environmental Properties Management
To: Miller R, James Smith
Document Control Desk, Office of Nuclear Material Safety and Safeguards, State of OK, Dept of Environmental Quality (DEQ)
References
Download: ML24017A055 (1)
v • d • e


Text

January 17, 2024

Mr. James Smith U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852-2738

Ms. Rachel Miller Oklahoma Department of Environmental Quality 707 North Robinson Oklahoma City, OK 73101

Re: Docket No. 07000925; License No. SNM-928 Cimarron Environmental Response Trust Burial Area #1 Redox Evaluation Report

Dear Recipients:

Solely as Trustee for the Cimarron Environmental Response Trust (CERT), Environmental Properties Management LLC (EPM) submits to the U. S. Nuclear Regulatory Commission (NRC) and the Oklahoma Department of Environmental Quality (DEQ) the attached Burial Area

  1. 1 Redox Evaluation Report.

As the NRC and the DEQ are aware, the use of an organic slurry during the 2017 construction of Groundwater Extraction Trench GETR-BA1-01 in Burial Area #1 (BA1) appeared to have created reducing conditions in groundwater in the vicinity of the extraction trench. As a result, the concentration of dissolved uranium decreased considerably in some of the monitor wells near that trench.

EPM initiated a quarterly groundwater sampling program to assess the impact of the reduced aquifer conditions on the concentration of uranium in groundwater in BA1. On March 25, 2020, EPM submitted Burial Area #1 Redox Evaluation Report. This report presented the data that had been received to that date and concluded aquifer redox potential in the affected area is increasing toward levels representative of pre-construction conditions and, as a result, the precipitated uranium is reoxidizi ng and aqueous uranium concentrations are increasing. Uranium groundwater concentrations are expected to fully rebound to pre-construction levels prior to the planned start of remediation activities The report also concluded that additional data are needed to confirm trends and projections.

Twelve more sampling events were conducted between the date of the 2020 report and the last redox sampling event, which was conducted in July 2023. This updated report tabulates data collected from select monitor wells prior to the 2017 construction of the extraction trench, through approximately five years of periodic groundwater sampling events. Figures present

9400 Ward Parkway

  • Kansas City, MO 64114 Tel: 405-642-5152
  • jlux@envpm.com

uranium concentration trend charts, plots of aquifer redox constituent data, and graphs of redox trends.

The report presents three key conclusions resulting from an evaluation of this data:

1. Generally, redox conditions have rebounded or appear to be rebounding to near background conditions.
2. The creation of aquifer reducing conditions is not anticipated to significantly impact the duration of groundwater remediation in BA1.
3. Additional redox sampling events are not recommended.

If you have any questions or desire clarification, please contact me at jlux@envpm.com or (405) 642-5152.

Sincerely,

Jeff Lux Project Manager

cc: (electronic copies only)

Stephanie Anderson and Linda Gersey, NRC Region IV Paul Davis, Keisha Cornelius, Pam Dizikes, David Cates, and Jonathan Reid, DEQ NRC Public Document Room vcpsubmittals@deq.ok.gov

9400 Ward Parkway

  • Kansas City, MO 64114 Tel: 405-642-5152
  • jlux@envpm.com

CIMARRON ENVIRONMENTAL RESPONSE TRUST BURIAL AREA #1 REDOX EVALUATION REPORT

CERT DECOMMISSIONING SUPPORT PROJECT NO. 153537

JANUARY 11, 2024 REVISION 0 CONTENTS

Introduction............................................................................................................ 1

Data Collection..................................................................................................... 3

Groundwater Monitoring Results..................................................................... 5 Pumping Test Fluids........................................................................................................ 6 Background Monitor Wells............................................................................................ 7 Trench Monitor Wells...................................................................................................... 7 Downgradient Monitor Wells....................................................................................... 8

Data Evaluation.................................................................................................... 9 Contributing Factors to De layed Uranium Concentration Rebound.................................................................................................................... 9 Estimated Impact to Water Treatment Operations............................................ 9

Conclusions........................................................................................................... 11

References........................................................................................................... 12

TABLES FIGURES APPENDIX A - BIOPOLYMER SLURRY DATA SHEET

January 2024 Burial Area #1 Redo x Evaluation Report Revision B

Introduction

This Burial Area #1 Redox Evaluation Report - Rev. B (Report) addresses the nature and extent of altered aquifer redox conditions and uranium concentrations caused by the introduction of organic slurry into the transition zone and alluvial water-bearing units in Burial Area #1 (BA1) at the Cimarron Environmental Re sponse Trust (CERT) remediation project site located in Guthrie, Oklahoma (Site). The impact of these changes on the effectiveness of planned BA1 remediation activities and recommendations for further evaluation are also presented. A previous Burial Area #1 Redox Evaluation Report was prepared in 2020 (Burns &

McDonnell, 2020) and submitted to the U.S. Nu clear Regulatory Commission (NRC) on March 24, 2020. This report presents updated monitoring results and associated conclusions and supersedes the 2020 report.

During remediation pilot test activities conducted at the Site in 2017 and 2018, Groundwater Extraction Trench GETR-BA1-01 was constructed within the transition zone in BA1. The location of GETR-BA1-01 is illustrated in Figure 1. The transition zone represents a lateral change in the hydrogeology from predominantly bedrock facies (sandstones of the Garber Formation) in the southern upland area of BA1 to alluvial material in the floodplain area of BA1. GETR-BA1-01 was excavated using an organic biopolymer slurry (refer to Appendix A for biopolymer data sheet) to prevent sidewall collapse of the unconsolidated material. A positive head (relative to the water table elevation) was maintained in the trench that prevented uranium-contaminated groundwater from entering the trench throughout construction. As the trench was excavated, groundwater extraction piping and monitor wells were installed and the trench was backfilled with gravel. As gravel was placed in the trench, slurry displaced by the gravel was pumped into two fractionation (frac) tanks. After the trench was backfilled, an enzyme was injected into the trench to break the biopolymer slurry. The slurry was then circulated within the trench to distribute the enzyme until the viscosity of the slurry was reduced to that of water. A positive head was also maintained within the trench throughout the slurry circulation process to prevent contaminated groundwater from contaminating the slurry. Enzyme was also added to and circulated within the slurry in the two frac tanks.

Following removal of the broken slurry from GETR-BA1-01, pumping tests were conducted.

Trench construction and pumping test details are provided in the Remediation Pilot Test Report (Burns & McDonnell, 2018) submitted to the NRC on June 19, 2018. The fluid pumped from the trench during the pumping tests was discharged to two additional frac tanks. Based on construction records, the volume of slurry added to the trench was approximately 30,000 gallons more than the volume removed prior to the start of the first pumping test, and approximately 35,000 gallons of fluid was extracted during the pumping tests. It was believed that the majority of the fluid recove red during the pumping test was broken slurry, not uranium-impacted groundwater from the surrounding formation. However, based on the groundwater monitoring results presented in this report, it appears that the extraction of water during the pump tests did not remove al l of the organics present in the slurry, and migration of organics from the trench continued after pumping was terminated.

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The results of groundwater sampling conducted following the pilot test showed significant decreases in aqueous uranium concentrations for several monitor wells located in or immediately adjacent to GETR-BA1-01. These decreased uranium concentrations prompted the evaluation of both uranium and redox pa rameters in groundwater near and downgradient from GETR-BA1-01. These results confirmed the presence of reducing conditions; therefore, a sampling program to define the nature and extent of reducing conditions and decreased uranium concentrations was initiated. Groundwater sampling events for uranium and other key geochemical parameters were conducted through July 2023 to monitor conditions near and downgradient of GETR-BA1-01.

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Data Collection

Ongoing groundwater monitoring events at the Site were conducted quarterly in 2018 following pilot test activities. The results of the first three quarterly sampling events indicated that uranium concentrations in some wells in the vicinity of the trench had decreased significantly. Based on these results, additional BA1 redox sampling events were conducted to assess redox parameters and uranium concentrations at monitor wells located near and downgradient of GETR-BA1-01. These sampling events, including the quarterly sampling events in 2018, are summarized below:

Uranium-Only Sampling Events: February 2018, May 2018, June 2018, August 2018, November 2018, August 2019, April 2020, Oc tober 2020, April 2021, October 2021, April 2022, and October 2022 Expanded Geochemical Sampling Events: September 2018, January/February 2019, July 2020, January 2021, July 2021, January 2022, July 2022, and July 2023

Uranium results from the annual environmental sampling events conducted in July of 2020, 2021, 2022, and 2023 were not included in the da ta evaluation presented herein. These annual groundwater samples were collected using the standard purge collection method. The samples collected as part of the redox evalua tion were collected via low-flow sampling to improve the accuracy and precision of field redox parameter data collection. Uranium samples collected prior to September 2018 were collected using the standard purge method.

The expanded geochemical sampling events typically included the following analytes for a subset of the monitor wells included in the BA1 redox sampling events: uranium-235, uranium-238, iron, manganese, methane, nitrate/nitrite, sulfate, and total organic carbon (TOC).

The locations of GETR-BA1-01 and groundwater monitor wells included in redox sampling events and discussed herein are presented on Figu re 1. Monitor wells were categorized based on location relative to GETR-BA1-01. These location categories include: background monitor wells, trench monitor wells (including both in-trench monitor wells and monitor wells cross-gradient from the trench), and downgradient monitor wells. Several wells that were installed during or following the pilot test, or were replaced in recent years, were coupled with previously existing nearby monitor wells to evaluate uranium concentration trends in a given area.

Background Monitor Wells: Monitor Wells 02W20 and 02W39 were selected as representative of background aquifer conditions. They are located hydraulically upgradient of GETR-BA1-01. These wells have not been impacted by trench construction activities and are used to evaluate general naturally occurring trends in groundwater upgradient of GETR-BA1-01.

Trench Monitor Wells: Several monitor wells (02W29, 02W31, and 02W46) were abandoned for trench construction. Replacement monitor wells (TR-10, 1405, and 1404) were installed in close proximity to the wells abandoned during trench construction. Three (3) monitor wells were installed within the constructed trench:

TR-08, TR-09, and TR-10 (coupled with historical data from 02W29). The following wells are considered near/cross-gradient to the trench: 1406, 02W28, TMW-09, 1405 (coupled with historical data from 02W31), TMW-05, 02W01, TMW-07, 02W02,

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02W09, and 1404 (coupled with historical data from 02W46). While Monitor Wells 02W01 and TMW-05 are located cross-gradient from the trench, they are significantly further from the trench than other monitor wells.

Downgradient Monitor Wells: The following wells were evaluated as part of the downgradient location category, in order of distance nearest to farthest from the trench:

o Alluvial Monitor Wells: 02W32, TMW-13 o Transition Zone Monitor Well: 02W13 o Alluvial Monitor Wells: 02W08, 02W07, 02W19, 02W14, 02W18, 02W38, 02W44, 1361, 1363, and 1365

During the GETR-BA1-01 pumping tests, recovered fluids (broken trench slurry and groundwater) were initially discharged to two (2) frac tanks, Tank 1 (SV26342L) and Tank 2 (SV29597L). Fluids were first discharged to Tank 1 and then discharged to Tank 2. In addition to the samples collected from the monitor wells described above, these frac tanks were sampled in September 2018 for redox parameters and uranium concentrations. Samples were collected from the top, middle, and bottom of each tank.

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Groundwater Monitoring Results

Total uranium concentrations were calculated by adding the mass concentrations of uranium-235 and uranium-238 for each sampling event. For samples where concentrations of uranium-235 or uranium-238 were below the laboratory detection limit, the laboratory reporting limit was used to represent the uranium concentration for that isotope in the total mass concentration calculation. Historical uranium concentration data prior to trench construction, along with uranium concentration data from redox sampling events (post trench construction), are displayed on Table 1. Uran ium concentration trend charts are presented on Figure 2a through 2c. Monitor Well TMW-05 is excluded from the uranium concentration trend charts since only one sample was collected post trench construction.

Several field parameters and analytes were assessed to evaluate redox trends in the vicinity of GETR-BA1-01. Field parameters included in the evaluation presented below include: pH, dissolved oxygen (DO), and oxidation-reduction potential (ORP). Because sampling conducted prior to September 2018 involved standard purging methodology, DO and ORP were not collected during sampling events prior to that sampling event. Field parameters are displayed on Table 2. Additional geochemical analytes included iron, manganese, methane, nitrate, sulfate, and total organic carbon (TOC). These additional geochemical analytical results are displayed on Table 3.

The biopolymer slurry used during trench cons truction acts as an electron donor that indigenous microorganisms use to reduce elec tron acceptors commonly present in aquifer systems (e.g., oxygen, nitrate, ferric iron, manganese, and sulfate). At circumneutral pH (between 6.5 and 7.5 standard units), and under oxidizing (high redox) conditions, uranium is present as mobile U(VI), typically in the uranyl carbonate form. However, as the redox potential decreases, uranium is reduced to the insoluble U(IV) form and precipitates out of groundwater, typically as the mineral uraninite (UO2). Iron-and sulfate-reducing bacteria are capable of respiring U(VI) as an alternative electron acceptor. In addition, U(VI) can be abiotically reduced to U(IV) through reactions with ferrous iron [Fe(II)] minerals formed under iron-reducing conditions.

Analytical results for the geochemical analytes and select field parameters, including aqueous concentrations of DO, iron, manganese, methane, nitrate, and sulfate, were displayed on radial redox plots using the Visual Bio' program dev eloped by Porewater Solutions and Surfer software. Radial redox plots were generated using the data collected during the expanded geochemical sampling events. The samples collected during the January 2019 sampling event were not analyzed for nitrate. To generate approximate radial redox plots for January 2019, the nitrate concentration data obtained during the September 2018 sampling were used. For samples where analytical concentrations we re below the laboratory detection limit, the laboratory reporting limit was used in the radial redox plots.

The area of the polygon representing redox cond itions for each monitor well was calculated and compared to the overall area of the chart to yield relative redox area (RRA) as a percentage. RRA percentages and correspondi ng redox conditions are listed below, in accordance with the Porewater Solutions guida nce document (Porewater Solutions, 2018):

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Aerobic zone (oxidizing): RRA > 60%

Slightly anaerobic: RRA = 50 to 60%

Moderately anaerobic: RRA = 20 to 49%

Strongly anaerobic (reducing): RRA < 20%

The monitor well RRA results are presented with the radial redox plots included in Figure 3.

The RRA results are also summarized on Table 4, with trend charts presented on Figure 4a through 4c.

Pumping Test Fluids During the GETR-BA1-01 pumping tests in November 2017, recovered fluids were initially discharged to Tank 1 and then discharged to Tank 2. Samples were collected from the top, middle, and bottom of each tank in February 2018. Based on the results presented below, Tank 1 (SV26342L) pump test fluids exhibited a higher concentration of organic carbon, a lower redox potential, and a lower uranium concentration in comparison with Tank 2 (SV29597L) fluids. The pump test fluids within the shallow tank sample intervals exhibited higher redox potential, presumably due to atmosphe ric interaction at the fluid surface. These analytical results are presented on Table 5.

The TOC concentrations reported for Tank 1 samp les were approximately double the levels reported for Tank 2, evidencing a higher quantity of organic carbon in the Tank 1 fluids recovered during the early phase of pump test ing. Consequently, uranium concentrations in Tank 1 (13.6 to 14.0 µg/L) were lower than those reported for Tank 2 (28.3 to 28.6 µg/L), and redox parameter results showed stronger redu cing conditions in Tank 1 (see below). In general, the TOC concentrations reported for frac tank samples were significantly higher than those reported for monitor wells.

The pH levels reported for frac tank samples were slightly higher than those reported for all monitor well samples collected during the September 2018 sampling event and DO concentrations reported in the frac tank samples were generally similar to those reported for all monitor well samples. ORP concentrations of -50.8 mV (top), -165.0 mV (middle), and -

169.2 mV (bottom) were reported for Tank 1. The ORP results for the middle and bottom samples were lower than those reported for a ll monitor wells. As expected, a higher ORP value was reported for the top sample due to the effects of atmospheric interaction at the fluid surface. ORP concentrations of 2.5 mV (top), -11.0 mV (middle) and -62.7 mV (bottom) were reported for Tank 2. The ORP results fo r the middle and bottom samples were generally similar to values reported for monitor wells located in and near the middle and upgradient (southern) portions of GETR-BA1-01, but higher than those reported for wells located in and near the downgradient (northern) portion of the trench, and for two of the nearest downgradient wells (TMW-13 and 02W32).

The frac tank sampling results confirmed that aqueous uranium concentrations are strongly influenced by redox conditions, and that redox conditions were significantly affected by the presence of organic carbon.

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Background Monitor Wells Background Monitor Well 02W20, located hydraulically upgradient of GETR-BA1-01, has exhibited relatively low total uranium concentrat ions, ranging from 0.37 micrograms per liter

(µg/L) (July 2022) to 1.55 µg/L (April 2017). Uranium concentrations are relatively stable at this well (see Table 1 and Figure 2a), with no discernible change in trend following trench construction activities. Background Monitor Well 02W39 is also located hydraulically upgradient of GETR-BA1-01, but is closer to th e trench and has historically exhibited higher total uranium concentrations. Total uranium concentrations have generally decreased from May 2013 to October 2022, from 851 µg/L to 112 µg/L, respectively. These decreases are likely attributed to the influx of lower concentration groundwater from the south.

These monitor wells exhibit relatively stable pH in the neutral range, ranging from 6.8 (02W39, February 2016) to 7.7 (02W20, July 2022). The ORP values observed at these monitor wells are positive and relatively variab le, ranging from 35.7 millivolts (mV) (02W20, September 2018) to 271 mV (02W39, January 2021). The DO values observed at these monitor wells are relatively variable, ranging from 0.08 milligrams per liter (mg/L) (02W20, July 2021 and July 2023) to 1.47 mg/L (02W39, July 2023).

The RRA (Figures 3 and 4a) for these monitor wells have typically been in the slightly anaerobic to aerobic range. The RRA percentage has ranged from 35.5% (02W20, July 2021) to 62.7% (02W39, July 2021).

Trench Monitor Wells As discussed in the Introduction, decreased uranium concentrations following trench construction were observed for several monitori ng wells located in or immediately adjacent to GETR-BA-01, including Wells 02W29 / TR-10, 02W28, 02W31 / 1405, TMW-05, TMW-07, 02W02, and 02W46 / 1404, likely influenced by the reducing conditions caused by the organic material present in the slurry used during trench construction activities.

Subsequent monitoring events conducted between February 2018 and July 2023 have indicated that in-and near-trench monitoring wells generally exhibit varying concentrations of uranium. Wells for which historical uranium data is available (i.e., uranium concentration data prior to trench construction) generally exhibit uranium concentration decreases following trench construction activities. Several wells exhibited significant decreases in uranium concentrations immediately following trench construction. These wells include 02W28, 1405, and TMW-07. One well in this area, 02W02, exhibited variable uranium concentrations, but did not appear to increase or decrease over time. However, uranium concentrations in several of these wells appeared to be decreasing even prior to trench installation, including 02W29 / TR-10, TMW-09, 02W01, and 1404. Several of the trench monitor wells do not have data available prior to 2017; these wells have exhibited relatively variable uranium concentrations, but do not show overall increases or decreases since construction of GETR-BA1-01 in 2017.

The in-and near-trench monitor wells exhibit relatively stable pH in the neutral range, ranging from 6.4 (TMW-09, February 2016) to 7.8 (1405, July 2022). Monitor Well TR-10, near the upgradient end of the trench, generally exhibits positive, variable ORP. Monitor wells slightly further downgradient (1406, TR-09, TMW-09, 02W28, and 1405) have generally exhibited

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increasing ORP since September 2018, with positive current ORP values. Monitor wells near the downgradient half of the trench (TR-08, TMW-07, and 1404) have generally exhibited increasing ORP since August 2019, but ORP values remain negative. DO concentrations at these wells are relatively variable, ranging from 0.05 mg/L (TR-08, August 2019) to 2.73 mg/L (02W02, July 2020). Increasing or decreasing trends for DO are generally not observed in these wells.

During the 2018 sampling event (i.e., the first geochemical sampling event following trench installation), several monitor wells (TR-09, TR-08, TMW-07, and 1404) exhibited RRA significantly below (more reducing/anaerobic environment) the conditions observed at background wells 02W20 and 02W39. Conditions at background wells 02W20 and 02W39 are used as estimates of redox conditions prior to trench construction activities. The reducing conditions observed at the trench wells during the first geochemical sampling, relative to the conditions observed at the background locations, are likely due to the organic material present in the slurry used during trench cons truction. The RRA for these wells has generally increased over time (less reducing/anaerobic environment), indicating that redox conditions are likely rebounding to the conditions similar to the conditions observed at background wells 02W20 and 02W39. The RRA at monitor well TR-09 is now in the upper moderately anaerobic range and similar to background conditions. The RRA for monitor wells TR-08, TMW-07, and 1404 have increased but remain slightly below background conditions. The RRA for remaining trench monitor wells that were included in the expanded geochemical sampling events (TR-10, 02W28, 1405, and 02W02) appear to be generally unaffected by trench installation activities and have remained similar to background conditions.

Downgradient Monitor Wells Uranium concentrations generally decrease with distance downgradient from GETR-BA1-01.

Uranium concentrations over time in each well exhibit varying trends. Uranium concentrations at one of the closest downgradient wells, 02W32, have generally increased since May 2018, but have not approached pre-trench construction concentrations. Two wells located cross-gradient from 02W32 (TMW-13 and 02W13) have exhibited relatively variable uranium concentrations but appear to decrease slightly af ter trench installation. The remaining further downgradient wells exhibit similar trends, wi th generally lower uranium concentrations observed since trench installation.

These monitor wells exhibit relatively stable pH in the neutral range, ranging from 6.2 (1365, February 2016) to 7.6 (1363, March 2015). ORP values are variable throughout the downgradient monitor wells and typically do not exhibit increasing or decreasing trends over time. DO concentrations at these wells are relatively variable, ranging from 0.03 mg/L (02W32, August 2019 and TMW-13, August 2019) to 3.43 mg/L (02W44, February 2019).

Increasing or decreasing trends for DO are generally not observed in these wells.

Monitor wells TMW-13 and 02W32 exhibited RRA significantly below background conditions in the September 2018 sampling event (i.e., the first geochemical sampling event following trench installation). The RRA for these wells have generally increased over time but remain slightly below background conditions. The RRA for monitor wells 1361, 1363, and 1365 appeared to be generally unaffected by trench installation activities and have remained similar to background conditions. The RRA for monitor well 02W08 has typically been slightly higher than background conditions.

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Data Evaluation

Contributing Factors to Delayed Uranium Concentration Rebound Several of the trench and downgradient monitor wells described above appear to have been affected by the altered redox conditions induced by the biopolymer slurry used during construction of GETR-BA1-01. Monitor wells TR-09, TR-08, TMW-07, 1404, TMW-13, and 02W32 exhibited altered redox conditions (as evidenced in Table 4) following trench construction but appear to be naturally returning to near background redox conditions (less reducing/anerobic environment). However, some of the monitor wells that exhibited lower uranium concentrations following trench construction appear to continue to exhibit uranium concentrations below pre-trench construction levels. This section presents other factors potentially linked to these sustained lower observed uranium concentrations.

Historically, uranium concentrations have been highly variable throughout BA1. Different sampling methods (standard purge vs. low flow sampling) have also been used for uranium analysis, further contributing to overall variability in results.

As depicted on Figure 5, the uranium concentration gradient in the vicinity of the trench is steep. Figure 5 depicts the extent of uranium impact based on the Representative concentrations presented in Facility Decommissioning Plan - Rev 3 (Environmental Properties Management, 2022) (D-Plan). Overall, uranium concentrations at monitor wells near the upgradient side of the trench (02W39, 02W29/TR-10, and TMW-09) appear to decrease consistently over time (see Table 1 and Figure 2b). These decreases are more likely attributed to natural plume migration in the direction of groundwater flow than sustained impacts from trench construction. This is supported by the relatively high RRA observed throughout this area (see Table 4).

Uranium isoconcentration plots using uranium resu lts from individual sampling events were generated annually from Q2 2017 through Q3 2023. These uranium time-series isoconcentration contours are included as Figure 6. The plume boundaries (defined as the extent of uranium exceeding 200 µg/L) depicted on these figures are smaller than the boundary depicted on Figure 5. This is due to the use of results from single sampling events (Figure 6) versus the use of uranium concentrations that represent the 95% upper confidence values for multiple sampling events.

Figure 6 shows some migration of the upgradi ent plume boundary to the north as discussed above. It also shows some migration of the eastern plume boundary in the vicinity of the trench. This is likely due to the fact that the trench was backfilled with gravel, and it now provides a more hydraulically conductive pa thway for groundwater flowing from the east toward the trench (and toward 02W28, 1405, and TMW-07).

Estimated Impact to Water Treatment Operations Despite some areas within BA1 that appear to exhibit both prolonged redox condition impacts from trench construction and reduced uranium concentrations, minimal impact to water treatment operations is expected. Initial contaminant mass recovery at system startup may be slightly lower than anticipated, but as groundwater that was unimpacted from trench

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construction is drawn toward the trench and extraction wells, redox conditions are anticipated to return to background.

In 2017, Clemson University prepared a study on microbial reduction of U(VI) to U(IV) at the site (Clemson, 2017). This study also evaluated the likelihood and rate of uranyl dissolution (i.e., the reoxidation of U(IV) to U(VI)) in the presence of oxygen and/or nitrate in site-specific samples. The study concluded that the rate of U(IV) re-oxidation in the presence of oxygen is on the order of hours to days and th at U(IV) precipitates would be short lived at the site. Based on these results, aqueous ur anium concentration reductions caused by increased anaerobic microbial activity induced by trench construction activities are expected to rebound under more natural oxic conditions. Additionally, extracted groundwater will be pumped into the top of a series of several vent ed holding tanks and other piping and process components, which is expected to expose the ext racted water to atmospheric oxygen prior to injection. Injection of oxygen-rich water in the injection trenches should also promote aerobic/oxidizing groundwater conditions and re sult in the dissolution/re-oxidation of U(IV) precipitates in the aquifer to U(VI) in the vicinity of the BA1 injection and extraction system.

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Conclusions

Broken biopolymer slurry high in organic material used during GETR-BA1-01 installation migrated downgradient from GETR-BA1-01. The organic content of the biopolymer slurry induced reducing conditions near and downgradient of the installed trench. Under these reducing conditions, uranium was reduced from t he soluble/mobile U(VI) state to the less soluble/mobile U(IV) state and it precipitated out of solution into the aquifer matrix.

Therefore, uranium concentrations in ground water near and downgradient of the trench decreased. Redox conditions, including RRA, were also impacted. Generally, redox conditions have rebounded or appear to be rebounding to near background conditions (less reducing/anerobic).

Uranium concentrations in some BA1 wells remain depressed, but this may be attributed to a number of other factors. Primary contributing factors include: variability of uranium concentrations at individual locations, plum e migration, and altered groundwater flow patterns induced by the increased hydraulic conductivity of trench backfill material.

Variability of uranium concentrations may also be affected by the use of different sampling techniques for certain events (i.e., low flow versus standard purge methods). Based on the observed redox trends, and results presented in t he 2017 Clemson study, the impacts of the broken biopolymer slurry from trench constructi on are not anticipated to significantly impact the duration of groundwater remediation in BA1.

Based on the BA1 data evaluation and conc lusions presented above, additional redox sampling events are not recommended at BA1. Uranium concentrations and select field parameters will continue to be monitored at some of the wells included in this Report during annual environmental sampling events. Following remediation system construction and start-up, uranium concentrations will continue to be evaluated during in-process groundwater monitoring, as presented in the D-Plan.

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References

Burns & McDonnell Engineering Company, Inc., 2018. Remediation Pilot Test Report prepared for Cimarron Environmental Response Trust, June.

Burns & McDonnell Engineering Company, Inc., 2020. Burial Area #1 Redox Evaluation Report, March.

Clemson University, 2017. Cimarron Uranium Reduction/Oxidation/Desorption Experiment, November.

Environmental Properties Management, 2022. Facility Decommissioning Plan - Rev 3,

October.

Porewater Solutions, 2018. Visual Bio: Radial Diagrams for Visualizing Natural and Enhanced Biodegradation Trends - v1.1 Users Guide, June.

12 Cimarron Environmental Response Trust TABLES

Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 02W20 - Background 5/21/2013 0.915 3/25/2015 1.25 4/25/2017 1.55 9/17/2018 0.557 1/31/2019 0.991 4/16/2020 0.684 7/16/2020 0.504 10/12/2020 0.756 1/22/2021 1.32 4/15/2021 0.827 7/15/2021 0.445 10/14/2021 0.657 1/19/2022 1.37 4/20/2022 0.840 7/8/2022 0.365 10/20/2022 0.503 7/21/2023 0.561 02W39 - Background 5/28/2013 851 3/25/2015 537 2/17/2016 600 5/10/2016 429 8/11/2016 469 10/18/2016 421 2/8/2017 344 4/25/2017 383 8/3/2017 392 11/8/2017 309 2/7/2018 234 5/8/2018 435 8/24/2018 232 9/17/2018 136 11/7/2018 223 4/16/2020 201 7/16/2020 178 10/19/2020 159 1/22/2021 172 4/15/2021 301 10/14/2021 143

Page 1 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 02W39 - Background 1/19/2022 176 4/20/2022 161 7/8/2022 165 10/20/2022 112 7/21/2023 260 02W091 - Trench 8/3/2012 2.23 5/14/2013 9.95 5/28/2014 1.83 3/25/2015 2.48 5/10/2016 2.00 5/2/2017 6.70 6/13/2018 4.13 9/17/2018 1.60 8/27/2019 3.10 7/22/2020 2.34 7/6/2021 7.80 7/14/2022 2.22 7/13/2023 3.26 02W29 / TR Trench 5/28/2013 1,570 3/25/2015 1,040 4/25/2017 735 12/4/2017 540 8/24/2018 459 9/17/2018 477 1/31/2019 439 8/29/2019 603 4/16/2020 378 7/16/2020 350 10/12/2020 366 1/21/2021 262 4/15/2021 372 7/15/2021 345 10/14/2021 287 1/19/2022 267 4/20/2022 225 7/8/2022 259 10/20/2022 181 7/21/2023 259

Page 2 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 1406 - Trench 12/4/2017 1,364 8/24/2018 1,122 9/18/2018 876 4/15/2020 1,414 7/16/2020 1,142 10/12/2020 986 1/21/2021 1,182 4/15/2021 1,253 7/15/2021 1,162 10/14/2021 879 TR Trench 12/4/2017 264 8/24/2018 1,009 9/18/2018 1,052 1/31/2019 976 8/29/2019 1,334 4/15/2020 871 7/16/2020 521 10/13/2020 273 1/21/2021 872 4/15/2021 312 7/15/2021 456 10/14/2021 754 1/19/2022 388 4/19/2022 546 7/8/2022 707 10/19/2022 491 7/21/2023 160 02W28 - Trench 8/1/2012 251 5/14/2013 255 5/27/2014 254 3/25/2015 428 5/10/2016 291 5/2/2017 301 6/13/2018 151 9/18/2018 93.2 1/30/2019 74.9 8/28/2019 53.1

Page 3 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 02W28 - Trench 4/15/2020 51.2 7/16/2020 38.9 7/22/2020 82.7 10/13/2020 35.5 1/21/2021 38.1 4/15/2021 60.9 7/6/2021 266 7/15/2021 155 10/13/2021 55.7 1/19/2022 25.6 4/19/2022 24.0 7/7/2022 20.7 10/19/2022 55.1 7/21/2023 16.3 TMW Trench 7/30/2012 3,760 5/14/2013 2,880 5/27/2014 2,410 3/25/2015 2,830 2/17/2016 2,620 5/10/2016 2,790 8/11/2016 2,420 10/18/2016 2,620 2/8/2017 2,578 5/2/2017 2,597 8/3/2017 2,607 11/9/2017 2,436 2/7/2018 2,589 5/8/2018 3,286 6/13/2018 2,256 8/24/2018 2,367 9/18/2018 2,012 11/7/2018 2,185 1/30/2019 953 8/28/2019 1,963 4/15/2020 1,812 7/16/2020 2,267 7/22/2020 2,063 10/13/2020 2,620 1/21/2021 2,337

Page 4 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L)

TMW Trench 4/15/2021 2,306 7/7/2021 1,933 7/15/2021 2,124 10/13/2021 2,004 7/13/2023 2,144 02W31 / 1405 - Trench 5/23/2013 997 3/25/2015 803 4/24/2017 783 12/4/2017 349 8/24/2018 311 9/18/2018 259 1/30/2019 288 8/29/2019 268 4/15/2020 206 7/16/2020 206 10/13/2020 194 1/21/2021 191 4/14/2021 162 7/14/2021 150 10/13/2021 130 1/18/2022 133 4/19/2022 113 7/7/2022 106 10/19/2022 101 7/21/2023 80.8 TMW Trench 5/28/2013 3.66 3/24/2015 3.22 4/24/2017 3.87 9/17/2018 0.146 02W01 - Trench 5/23/2013 2,720 3/25/2015 2,670 2/17/2016 2,370 5/10/2016 1,550 8/11/2016 1,630 10/18/2016 2,380

Page 5 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 02W01 - Trench 2/8/2017 2,309 4/24/2017 1,974 8/3/2017 1,984 11/9/2017 2,055 2/7/2018 2,178 5/8/2018 2,067 8/24/2018 1,885 11/7/2018 2,006 4/15/2020 1,265 7/15/2020 1,489 10/13/2020 1,774 1/21/2021 1,844 4/14/2021 1,853 7/14/2021 1,579 10/13/2021 1,733 TR Trench 12/4/2017 85.5 8/24/2018 282 9/18/2018 269 1/30/2019 492 8/29/2019 1,052 4/15/2020 383 7/16/2020 398 10/13/2020 283 1/21/2021 314 4/14/2021 463 7/14/2021 420 10/13/2021 365 1/18/2022 246 4/19/2022 293 7/7/2022 268 10/19/2022 228 7/20/2023 182 TMW Trench 5/21/2013 220 3/24/2015 221 4/24/2017 190 9/18/2018 22.8 1/29/2019 62.1

Page 6 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L)

TMW Trench 8/29/2019 17.5 4/15/2020 30.4 7/15/2020 48.8 10/13/2020 34.5 1/20/2021 97.4 4/14/2021 118 7/14/2021 149 10/13/2021 36.9 1/18/2022 71.5 4/19/2022 90.1 7/7/2022 115 10/19/2022 50.1 7/20/2023 87.6 02W02 - Trench 3/24/2015 1,910 4/24/2017 2,346 9/18/2018 1,670 1/30/2019 2,934 8/29/2019 1,833 4/15/2020 2,023 7/15/2020 2,144 10/13/2020 1,569 1/20/2021 2,469 4/14/2021 2,682 7/14/2021 2,653 10/13/2021 984 1/18/2022 1,821 7/7/2022 1,670 7/21/2023 1,690 02W46 / 1404 - Trench 5/21/2013 4,330 3/24/2015 1,850 4/24/2017 1,810 12/4/2017 503 8/24/2018 110 9/18/2018 81.4 1/29/2019 48.4 8/29/2019 49.2 4/14/2020 32.7

Page 7 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 02W46 / 1404 - Trench 7/15/2020 40.8 10/13/2020 36.0 1/20/2021 33.5 4/14/2021 31.6 7/14/2021 82.0 10/13/2021 77.4 1/18/2022 22.5 4/19/2022 18.7 7/7/2022 40.4 10/19/2022 3.97 7/20/2023 29.5 TMW Downgradient 7/30/2012 1,280 5/13/2013 1,170 5/27/2014 2,540 3/24/2015 852 5/10/2016 4,510 6/12/2018 227 9/18/2018 224 1/29/2019 1,479 8/28/2019 2,564 4/14/2020 357 7/15/2020 722 10/14/2020 521 1/20/2021 460 4/14/2021 1,022 7/6/2021 1,145 7/14/2021 1,480 10/13/2021 1,115 1/18/2022 595 4/19/2022 492 7/7/2022 337 10/19/2022 208 7/20/2023 365 02W32 - Downgradient 8/1/2012 3,410 5/13/2013 249 5/27/2014 470 3/24/2015 1,190

Page 8 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 02W32 - Downgradient 2/17/2016 283 5/10/2016 218 8/11/2016 420 10/18/2016 1,270 12/15/2016 1,569 2/7/2017 1,032 8/3/2017 5,036 11/9/2017 2,175 2/7/2018 57.5 5/8/2018 61.1 6/13/2018 71.5 8/27/2018 51.5 9/19/2018 53.9 11/7/2018 112 1/29/2019 113 8/28/2019 155 4/15/2020 130 7/15/2020 192 7/21/2020 155 10/13/2020 179 1/20/2021 171 4/14/2021 123 7/6/2021 162 7/14/2021 93.7 10/13/2021 185 1/18/2022 168 4/19/2022 152 7/6/2022 145 10/18/2022 165 7/20/2023 231 02W13 - Downgradient 5/22/2013 32.3 3/24/2015 21.1 4/24/2017 30.2 9/19/2018 10.3 4/14/2020 16.5 7/14/2020 15.2 10/13/2020 5.60

Page 9 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 02W08 - Downgradient 8/2/2012 429 5/13/2013 187 5/27/2014 52.2 3/24/2015 739 2/17/2016 400 5/10/2016 54.8 8/11/2016 26.8 10/18/2016 29.8 2/7/2017 496 8/3/2017 381 11/9/2017 689 2/7/2018 146 5/8/2018 182 6/13/2018 11.7 8/27/2018 42.2 9/19/2018 5.00 11/7/2018 66.5 1/29/2019 13.1 8/28/2019 4.60 4/14/2020 7.80 7/14/2020 4.20 10/14/2020 4.21 1/20/2021 4.93 4/13/2021 14.2 7/6/2021 102 7/13/2021 33.9 10/12/2021 3.74 1/18/2022 4.70 4/18/2022 4.12 7/6/2022 4.11 10/18/2022 3.79 7/20/2023 7.55 02W07 - Downgradient 5/22/2013 975 3/24/2015 320 4/20/2017 1,478 1/28/2019 249 8/29/2019 973 4/14/2020 106

Page 10 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 02W07 - Downgradient 7/15/2020 10.4 10/14/2020 6.31 1/20/2021 105 4/14/2021 116 7/13/2021 245 10/12/2021 5.63 1/18/2022 6.28 7/6/2022 119 02W14 - Downgradient 5/22/2013 228 3/23/2015 289 4/24/2017 306 4/14/2020 79.0 7/14/2020 151 10/19/2020 125 1/20/2021 85.2 4/13/2021 90.1 7/13/2021 83.1 10/12/2021 93.6 1/17/2022 87.7 4/18/2022 113 7/6/2022 99.1 10/18/2022 81.3 7/19/2023 58.0 02W19 - Downgradient 5/22/2013 672 3/23/2015 157 4/20/2017 1,306 1/28/2019 225 4/14/2020 220 7/14/2020 296 10/14/2020 276 1/19/2021 160 4/13/2021 161 7/13/2021 252 10/12/2021 234 1/17/2022 202 4/18/2022 326

Page 11 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 02W19 - Downgradient 7/6/2022 263 10/18/2022 355 7/19/2023 158 02W18 - Downgradient 5/22/2013 170 3/23/2015 193 4/20/2017 504 1/28/2019 65.7 4/14/2020 145 7/14/2020 148 10/14/2020 137 1/19/2021 121 4/13/2021 109 7/13/2021 75.1 10/12/2021 155 02W38 - Downgradient 5/22/2013 176 3/23/2015 392 4/24/2017 198 4/14/2020 24.8 7/14/2020 47.1 10/14/2020 47.7 1/19/2021 19.4 4/13/2021 14.6 7/13/2021 26.7 10/12/2021 95.0 1/17/2022 66.1 4/18/2022 28.8 7/5/2022 16.8 10/18/2022 34.5 7/19/2023 31.3 02W44 - Downgradient 8/2/2012 363 5/13/2013 189 5/27/2014 250 3/24/2015 945 2/17/2016 447 5/10/2016 226 8/11/2016 208 10/18/2016 275 12/15/2016 307

Page 12 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 02W44 - Downgradient 2/7/2017 345 8/3/2017 1,164 11/9/2017 806 2/7/2018 481 5/8/2018 197 6/13/2018 96.7 8/27/2018 226 11/7/2018 182 1/28/2019 25.4 8/28/2019 61.6 4/13/2020 23.3 7/13/2020 96.5 7/22/2020 92.8 10/14/2020 83.6 1/19/2021 13.9 4/13/2021 10.8 7/6/2021 50.0 7/13/2021 23.0 10/11/2021 109 1/17/2022 191 4/18/2022 61.1 7/5/2022 16.8 10/18/2022 105 7/19/2023 79.7 1361 - Downgradient 10/16/2012 262 5/22/2013 69.8 3/23/2015 248 2/17/2016 83.6 5/9/2016 40.4 8/11/2016 44.1 10/18/2016 58.7 2/7/2017 169 4/20/2017 75.8 8/2/2017 288 11/9/2017 309 2/7/2018 131 5/8/2018 48.4 8/27/2018 45.2 11/7/2018 119

Page 13 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 1361 - Downgradient 4/13/2020 21.7 7/14/2020 36.6 10/19/2020 30.6 1/19/2021 30.3 4/12/2021 22.0 7/12/2021 14.6 10/11/2021 56.5 1/17/2022 61.8 4/18/2022 43.8 7/5/2022 17.9 10/17/2022 48.2 7/19/2023 24.2 1365 - Downgradient 5/22/2013 89.7 12/16/2014 123 3/23/2015 117 2/17/2016 116 5/9/2016 47.7 8/11/2016 28.7 10/18/2016 63.6 2/7/2017 72.0 4/20/2017 64.6 8/2/2017 111 11/9/2017 148 2/7/2018 96.6 5/8/2018 52.5 8/27/2018 41.8 11/7/2018 67.9 4/13/2020 10.6 7/14/2020 14.2 10/19/2020 17.2 1/18/2021 6.81 4/12/2021 8.10 7/12/2021 6.17 10/11/2021 12.5 1/17/2022 28.5 4/18/2022 12.3 7/5/2022 8.29 10/17/2022 21.9 7/19/2023 15.2

Page 14 of 15 Preparer: A. Anstaett, Date: 10/23/23 Table 1 - Total Uranium Concentrations Reviewer: B. Lockwood, Date: 12/15/2023 BA1 Redox Evaluation Cimarron Remediation Site

Date Total Uranium (g/L) 1363 - Downgradient 5/22/2013 98.4 12/16/2014 104 3/23/2015 45.6 4/20/2017 48.0 4/13/2020 14.5 7/13/2020 101 10/14/2020 41.6 1/18/2021 17.8 4/12/2021 20.7 7/12/2021 22.0 10/11/2021 12.8 1/17/2022 14.0 4/18/2022 14.2 7/5/2022 11.7 10/17/2022 12.4 7/19/2023 15.2

Notes:

1Sample collected from 02W09 using standard purge method during August 2019.

Samples at 02W09 after August 2019 were collected using low flow method.

g/L - micrograms per liter Data obtained prior to trench construction.

Page 15 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 02W20 - Background 5/21/2013 -- -- 6.90 3/23/2015 -- -- 7.40 4/25/2017 -- -- 7.50 9/17/2018 0.60 35.7 7.15 1/31/2019 0.38 72.7 7.25 2/13/2019 0.53 55.3 7.30 4/16/2020 1.04 117 7.56 7/16/2020 0.68 206 7.11 10/12/2020 0.17 106 7.09 1/22/2021 0.26 242 7.10 4/15/2021 0.39 191 7.10 7/15/2021 0.08 192 7.38 10/14/2021 0.16 152 7.68 1/19/2022 0.47 201 7.38 4/20/2022 0.50 71.0 7.10 7/8/2022 0.20 53.6 7.72 10/20/2022 0.35 135 7.10 7/21/2023 0.08 46.2 7.03 02W39 - Background 5/28/2013 -- -- 7.10 3/25/2015 -- -- 7.30 2/17/2016 -- -- 6.83 5/10/2016 -- -- 7.20 8/11/2016 -- -- 7.00 10/18/2016 -- -- 7.30 11/7/2016 -- -- 7.26 2/8/2017 -- -- 7.40 8/3/2017 -- -- 7.50 2/7/2018 -- -- 7.50 5/8/2018 -- -- 7.00 8/24/2018 -- -- 7.29 9/17/2018 0.51 40.0 7.07 11/8/2018 -- -- 7.40 4/16/2020 1.22 126 7.44 7/16/2020 0.53 197 7.14 10/19/2020 1.10 259 7.16 1/22/2021 0.25 271 7.10 4/15/2021 0.84 187 7.20 7/15/2021 1.44 192 7.19

Page 1 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 02W39 - Background 10/14/2021 0.16 224 7.70 1/19/2022 0.48 246 7.30 4/20/2022 0.63 53.5 7.10 7/8/2022 0.75 77.3 7.41 10/20/2022 0.29 103 7.50 7/21/2023 1.47 119 6.88 02W091 - Trench 8/3/2012 -- -- 7.40 5/14/2013 -- -- 6.70 5/28/2014 -- -- 7.06 3/25/2015 -- -- 7.60 5/10/2016 -- -- 7.20 5/2/2017 -- -- 7.50 6/13/2018 -- -- 7.36 9/17/2018 0.50 29.8 7.10 7/22/2020 -- -- 7.46 7/6/2021 -- -- 7.24 TR Trench 7/17/2018 0.49 4.10 6.98 8/24/2018 -- -- 7.13 1/31/2019 0.19 51.5 7.29 2/13/2019 0.38 67.4 7.31 8/29/2019 0.16 54.0 6.87 4/16/2020 1.30 137 7.05 7/16/2020 1.00 198 6.95 10/12/2020 0.79 274 6.96 1/21/2021 0.85 148 7.00 4/15/2021 0.77 152 7.10 7/15/2021 0.48 190 7.19 10/14/2021 1.06 243 7.35 1/19/2022 0.54 243 7.28 4/20/2022 1.61 53.8 6.90 7/8/2022 0.57 68.1 7.18 10/20/2022 0.44 169 6.70 7/21/2023 1.74 59.4 6.80

Page 2 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 1406 - Trench 12/4/2017 -- -- 7.10 8/24/2018 -- -- 7.15 9/18/2018 0.55 -23.3 6.83 4/15/2020 1.69 88.7 6.59 7/16/2020 0.38 199 6.91 10/12/2020 0.26 282 6.99 1/21/2021 0.72 137 6.70 4/15/2021 1.29 139 6.90 7/15/2021 0.45 178 7.00 10/14/2021 0.70 253 7.40 TR Trench 8/24/2018 -- -- 7.10 9/18/2018 0.48 -78.1 6.49 1/31/2019 0.19 -74.7 7.06 2/13/2019 1.40 -35.5 7.18 8/29/2019 0.11 64.7 6.84 4/15/2020 0.60 58.2 6.70 7/16/2020 0.33 29.3 6.95 10/13/2020 0.26 -28.8 7.04 1/21/2021 0.13 4.10 6.80 4/15/2021 0.16 -20.4 7.10 7/15/2021 0.12 84.5 7.16 10/14/2021 0.74 274 7.38 1/19/2022 1.99 67.6 7.24 4/19/2022 0.30 75.4 6.80 7/8/2022 0.18 69.4 6.82 10/19/2022 0.24 48.6 7.00 7/21/2023 0.13 98.7 6.89 02W28 - Trench 8/1/2012 -- -- 7.13 5/14/2013 -- -- 6.90 5/27/2014 -- -- 6.90 3/25/2015 -- -- 7.00 5/10/2016 -- -- 7.00 5/2/2017 -- -- 7.30 6/13/2018 -- -- 7.39 9/18/2018 0.50 8.40 6.91 1/30/2019 0.53 89.5 7.29 2/13/2019 0.78 77.0 7.33

Page 3 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 02W28 - Trench 8/28/2019 0.25 80.4 7.04 4/15/2020 1.19 69.6 6.95 7/16/2020 0.40 157 7.06 10/13/2020 0.28 207 7.21 1/21/2021 1.01 152 7.10 4/15/2021 0.62 245 7.20 7/15/2021 0.34 238 7.24 10/13/2021 0.21 98.6 7.69 1/19/2022 0.68 122 7.30 4/19/2022 0.52 78.6 7.10 7/7/2022 0.17 68.2 7.71 10/19/2022 0.45 52.7 7.30 7/21/2023 0.16 98.0 7.03 TMW Trench 7/30/2012 -- -- 6.74 5/14/2013 -- -- 6.70 5/27/2014 -- -- 7.10 3/25/2015 -- -- 6.90 2/17/2016 -- -- 6.38 5/10/2016 -- -- 6.90 8/11/2016 -- -- 6.80 10/18/2016 -- -- 7.10 2/8/2017 -- -- 7.40 5/2/2017 -- -- 7.20 8/3/2017 -- -- 7.20 11/9/2017 -- -- 7.30 2/7/2018 -- -- 7.20 5/8/2018 -- -- 6.93 6/13/2018 -- -- 7.23 8/24/2018 -- -- 7.12 9/18/2018 0.40 17.1 6.80 11/7/2018 -- -- 7.06 1/30/2019 0.24 63.5 7.14 2/12/2019 0.33 78.5 7.20 8/28/2019 0.11 34.5 6.95 4/15/2020 0.66 44.9 6.85 7/16/2020 0.36 168 6.94 1/21/2021 0.28 235 6.90 4/15/2021 0.28 249 7.10

Page 4 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU)

TMW Trench 7/15/2021 0.33 256 7.18 10/13/2021 0.11 110 7.48 1405 - Trench 12/4/2017 -- -- 7.10 8/24/2018 -- -- 7.22 9/18/2018 0.49 10.9 6.90 1/30/2019 0.19 136 7.21 2/12/2019 0.35 107 7.32 8/29/2019 0.22 15.6 7.02 4/15/2020 0.65 31.2 6.97 7/16/2020 0.34 83.1 7.03 10/13/2020 0.23 226 7.18 1/21/2021 0.23 83.1 7.00 4/14/2021 0.18 71.1 7.00 7/14/2021 0.20 106 7.31 10/13/2021 0.11 63.8 7.57 1/18/2022 0.63 66.2 7.17 4/19/2022 0.19 53.1 7.10 7/7/2022 0.25 55.6 7.82 10/19/2022 0.25 37.3 7.20 7/21/2023 0.08 60.3 7.01 TMW Trench 5/28/2013 -- -- 6.90 3/24/2015 -- -- 7.30 4/24/2017 -- -- 7.40 9/17/2018 0.65 -72.6 7.01 02W01 - Trench 5/23/2013 -- -- 7.20 3/25/2015 -- -- 6.84 2/17/2016 -- -- 6.77 5/10/2016 -- -- 6.80 8/11/2016 -- -- 6.80 10/18/2016 -- -- 7.20 2/8/2017 -- -- 7.50 4/24/2017 -- -- 7.20

Page 5 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 02W01 - Trench 8/3/2017 -- -- 7.30 11/9/2017 -- -- 7.30 2/7/2018 -- -- 7.30 5/8/2018 -- -- 6.87 8/24/2018 -- -- 7.11 11/7/2018 -- -- 7.07 4/15/2020 3.41 162 6.76 7/15/2020 0.86 133 6.84 10/13/2020 1.09 227 7.01 1/21/2021 2.10 126 7.00 4/14/2021 1.33 112 7.00 7/14/2021 0.14 137 7.11 10/13/2021 0.13 87.7 7.41 TR Trench 8/24/2018 -- -- 7.26 9/18/2018 0.50 -99.9 6.82 1/30/2019 0.15 -110 7.17 2/12/2019 0.35 -95.6 7.21 8/29/2019 0.05 -114 6.85 4/15/2020 0.62 -87.3 6.82 7/16/2020 0.30 -84.4 7.00 10/13/2020 0.20 -71.1 7.17 1/21/2021 0.15 -51.3 7.00 4/14/2021 0.25 -56.9 7.00 7/14/2021 0.18 -53.3 7.21 10/13/2021 0.11 -58.9 7.49 1/18/2022 0.21 -46.6 7.16 4/19/2022 0.15 -48.1 7.00 7/7/2022 0.15 -29.9 7.72 10/19/2022 0.37 -71.4 7.10 7/20/2023 0.11 -62.5 6.92 TMW Trench 5/21/2013 -- -- 7.30 3/24/2015 -- -- 7.20 4/24/2017 -- -- 7.40 9/18/2018 0.37 -103 6.83 1/29/2019 0.10 -93.3 7.22 2/12/2019 0.35 -95.4 7.23

Page 6 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU)

TMW Trench 8/29/2019 0.10 -119 6.98 4/15/2020 0.70 -90.3 6.90 7/15/2020 0.35 -107 6.98 10/13/2020 0.24 -69.8 7.20 1/20/2021 0.12 -64.5 7.00 4/14/2021 0.48 -52.8 7.00 7/14/2021 0.07 -38.5 7.23 10/13/2021 0.73 -73.8 7.55 1/18/2022 0.14 -65.2 7.19 4/19/2022 0.12 -46.8 7.00 7/7/2022 0.12 -41.4 7.81 10/19/2022 0.20 -94.8 7.20 7/20/2023 0.37 -51.0 6.95 02W02 - Trench 3/24/2015 -- -- 7.70 4/24/2017 -- -- 7.30 9/18/2018 0.81 3.50 6.72 1/30/2019 0.84 163 7.10 2/12/2019 0.42 130 7.13 8/29/2019 0.14 -56.6 6.81 4/15/2020 0.74 136 6.69 7/15/2020 2.73 131 6.75 10/13/2020 0.54 6.20 7.03 1/20/2021 0.60 105 6.80 4/14/2021 0.22 99.5 6.90 7/14/2021 0.19 91.7 7.09 10/13/2021 0.10 -9.1 7.42 1/18/2022 1.56 89.9 7.12 7/7/2022 0.34 39.7 7.51 7/21/2023 0.36 37.9 6.82 1404 - Trench 12/4/2017 -- -- 6.70 8/18/2018 0.40 -104 6.83 8/24/2018 -- -- 7.29 1/29/2019 0.09 -95.5 7.26 2/12/2019 0.42 -76.3 7.26 8/29/2019 0.10 -141 7.03 4/14/2020 0.60 -70.8 7.42 7/15/2020 0.40 -116 6.99

Page 7 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 1404 - Trench 10/13/2020 0.25 -72.0 7.21 1/20/2021 0.12 -60.0 7.20 4/14/2021 0.13 -2.50 7.10 7/14/2021 0.58 -76.7 7.29 10/13/2021 0.10 -75.2 7.57 1/18/2022 0.24 -53.3 7.28 4/19/2022 0.26 -65.4 7.10 7/7/2022 0.17 -52.9 7.32 10/19/2022 0.28 -98.6 7.30 7/20/2023 0.20 -104 7.01 TMW Downgradient 7/30/2012 -- -- 6.95 5/13/2013 -- -- 7.20 5/27/2014 -- -- 7.07 3/24/2015 -- -- 7.20 5/10/2016 -- -- 6.70 8/11/2016 -- -- 7.00 6/12/2018 -- -- 7.35 9/18/2018 0.48 -105 6.81 1/29/2019 0.29 -28.1 7.07 2/11/2019 0.40 -42.2 7.15 8/28/2019 0.03 -115 6.81 4/14/2020 0.83 3.40 7.15 7/15/2020 0.33 -67.9 6.84 10/14/2020 0.30 -29.3 6.98 1/20/2021 0.51 -5.40 6.90 4/14/2021 0.41 4.50 6.90 7/14/2021 0.17 -36.4 7.18 10/13/2021 0.51 -58.8 7.27 1/18/2022 0.20 7.30 6.99 4/19/2022 0.16 -22.2 6.90 7/7/2022 0.22 -9.40 7.17 10/19/2022 0.19 -116 7.10 7/20/2023 0.06 -74.3 6.96

Page 8 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 02W32 - Downgradient 8/1/2012 -- -- 6.97 5/13/2013 -- -- 7.00 5/27/2014 -- -- 7.10 3/24/2015 -- -- 7.10 2/17/2016 -- -- 6.45 5/10/2016 -- -- 6.90 8/11/2016 -- -- 6.90 10/18/2016 -- -- 7.10 2/7/2017 -- -- 7.40 8/3/2017 -- -- 7.40 11/9/2017 -- -- 7.50 2/7/2018 -- -- 7.30 5/8/2018 -- -- 6.96 6/12/2018 -- -- 7.32 8/27/2018 -- -- 7.10 9/19/2018 1.05 -107.30 6.82 11/7/2018 0.30 -6.10 7.08 1/29/2019 -- -- 7.11 2/11/2019 0.35 -5.20 7.18 8/28/2019 0.03 -88.4 6.96 4/15/2020 0.75 26.5 6.72 7/15/2020 0.37 -21.3 6.87 10/13/2020 0.25 -38.6 7.14 1/20/2021 0.35 15.7 6.80 4/14/2021 0.23 97.6 6.90 7/14/2021 0.13 99.7 7.01 10/13/2021 0.18 -49.5 7.46 1/18/2022 0.22 -28.3 7.10 4/19/2022 0.24 -24.7 6.70 7/6/2022 0.17 -3.60 6.98 10/18/2022 0.53 -70.4 7.00 7/20/2023 0.05 -14.4 6.78 02W13 - Downgradient 5/22/2013 -- -- 6.70 3/24/2015 -- -- 6.90 4/24/2017 -- -- 7.10

Page 9 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 02W13 - Downgradient 9/19/2018 1.20 -64.1 6.58 4/14/2020 0.89 29.7 7.05 7/14/2020 0.64 -18.7 6.67 10/13/2020 0.23 -35.2 6.89 02W08 - Downgradient 8/2/2012 -- -- 6.58 5/13/2013 -- -- 7.10 5/27/2014 -- -- 7.00 3/24/2015 -- -- 6.90 2/17/2016 -- -- 6.39 5/10/2016 -- -- 6.70 8/11/2016 -- -- 7.00 10/18/2016 -- -- 7.10 2/7/2017 -- -- 7.40 8/3/2017 -- -- 7.30 11/9/2017 -- -- 7.30 2/7/2018 -- -- 7.20 5/8/2018 -- -- 6.75 6/12/2018 -- -- 7.21 8/19/2018 0.80 17.4 6.75 8/27/2018 -- -- 7.01 11/7/2018 -- -- 7.08 1/29/2019 0.47 88.0 7.04 2/11/2019 0.89 199 7.08 8/28/2019 0.05 69.6 6.85 4/14/2020 1.73 38.5 7.10 7/14/2020 0.36 79.9 6.81 10/14/2020 0.26 161 7.02 1/20/2021 0.23 91.8 6.90 4/13/2021 0.90 136 6.90 7/13/2021 0.23 171 7.00 10/12/2021 0.14 142 7.30 1/18/2022 0.33 146 7.05 4/18/2022 0.12 44.7 7.20 7/6/2022 0.21 38.7 7.21 10/18/2022 0.47 78.7 7.10 7/20/2023 0.09 70.1 6.88

Page 10 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 02W07 - Downgradient 5/22/2013 -- -- 7.00 3/24/2015 -- -- 7.20 4/20/2017 -- -- 7.24 1/28/2019 0.70 37.3 7.04 2/11/2019 1.08 23.5 7.08 8/29/2019 0.06 -108 6.75 4/14/2020 0.64 -38.1 7.17 7/15/2020 0.42 78.1 6.83 10/14/2020 0.39 105 6.97 1/20/2021 0.70 76.1 6.90 4/14/2021 0.94 55.4 6.90 7/13/2021 0.45 -41.6 7.13 10/12/2021 0.12 146 7.26 1/18/2022 0.24 134 7.05 7/6/2022 0.42 28.5 7.31 02W14 - Downgradient 5/22/2013 -- -- 7.10 3/23/2015 -- -- 7.10 4/14/2020 0.54 -77.8 7.19 7/14/2020 0.32 -80.7 6.89 10/19/2020 0.27 -22.7 6.91 1/20/2021 0.14 -67.6 7.00 4/13/2021 0.14 15.1 6.96 7/13/2021 0.11 -53.0 7.12 10/12/2021 0.10 -45.8 7.34 1/17/2022 1.10 -29.2 7.06 4/18/2022 0.09 -44.8 7.20 7/6/2022 0.10 -52.7 7.34 10/18/2022 0.53 -21.2 7.10 7/19/2023 0.09 -61.7 6.91 02W19 - Downgradient 5/22/2013 -- -- 7.00 3/23/2015 -- -- 7.20 4/20/2017 -- -- 7.20 1/28/2019 0.10 32.3 7.05 2/11/2019 1.10 59.2 7.05 4/14/2020 0.56 -43.5 7.27

Page 11 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 02W19 - Downgradient 7/14/2020 0.30 -27.8 6.83 10/14/2020 0.23 -54.4 7.05 1/19/2021 0.18 -29.2 6.90 4/13/2021 0.10 -11.5 6.80 7/13/2021 0.11 -23.0 7.06 10/12/2021 0.12 -27.3 7.30 1/17/2022 1.23 84.6 7.11 4/18/2022 0.49 16.1 7.20 7/6/2022 0.18 -17.4 7.42 10/12/2022 0.43 -12.7 7.10 7/19/2023 0.09 -62.0 7.00 02W18 - Downgradient 5/22/2013 -- -- 7.20 3/23/2015 -- -- 7.20 4/20/2017 -- -- 7.20 1/28/2019 0.29 76.9 7.14 2/11/2019 0.99 31.4 7.21 4/14/2020 0.67 -55.7 7.11 7/14/2020 0.32 -54.8 6.92 10/14/2020 0.22 -43.7 7.12 1/19/2021 0.15 -67.2 6.90 4/13/2021 0.18 -15.1 6.90 7/13/2021 0.22 -24.4 7.15 10/12/2021 1.55 -65.0 7.32 02W38 - Downgradient 5/22/2013 -- -- 7.30 3/23/2015 -- -- 7.10 4/24/2017 -- -- 7.30 4/14/2020 1.65 70.0 7.09 7/14/2020 0.59 -15.4 6.85 10/14/2020 0.29 157 7.04 1/19/2021 1.75 -7.70 6.80 4/13/2021 1.24 141 7.00 7/13/2021 0.13 -31.0 7.08 10/12/2021 0.08 -20.0 7.31 1/17/2022 0.88 67.2 7.13 4/18/2022 0.29 49.4 7.20 7/5/2022 0.23 47.6 7.23 10/18/2022 0.32 -68.7 7.10

Page 12 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 02W38 - Downgradient 7/19/2023 0.17 -62.4 6.81 02W44 - Downgradient 8/2/2012 -- -- 6.85 5/13/2013 -- -- 7.00 5/27/2014 -- -- 6.90 3/24/2015 -- -- 6.70 2/17/2016 -- -- 6.52 5/10/2016 -- -- 6.60 8/11/2016 -- -- 6.90 10/18/2016 -- -- 7.10 2/7/2017 -- -- 7.40 8/3/2017 -- -- 7.00 11/9/2017 -- -- 7.30 2/7/2018 -- -- 7.30 5/8/2018 -- -- 6.89 6/12/2018 -- -- 7.26 8/27/2018 -- -- 7.09 11/7/2018 -- -- 7.08 1/28/2019 2.37 65.5 7.08 2/11/2019 3.43 40.4 7.13 8/28/2019 0.16 -71.2 6.89 4/13/2020 2.19 45.6 7.35 7/13/2020 0.34 -31.3 7.06 10/14/2020 0.20 -6.90 7.09 1/19/2021 2.04 112 6.90 4/13/2021 2.17 84.2 6.90 7/13/2021 0.78 33.3 7.15 10/11/2021 0.18 25.7 7.25 1/17/2022 0.70 -17.5 7.05 4/18/2022 1.09 46.7 7.30 7/5/2022 0.36 54.4 7.33 10/18/2022 0.46 -58.9 7.00 7/19/2023 0.18 -21.3 6.85 1361 - Downgradient 5/22/2013 -- -- 7.10 3/23/2015 -- -- 7.00 2/17/2016 -- -- 6.85 5/9/2016 -- -- 6.90 8/11/2016 -- -- 7.10

Page 13 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 1361 - Downgradient 10/18/2016 -- -- 7.30 2/7/2017 -- -- 7.50 4/20/2017 -- -- 7.30 8/2/2017 -- -- 7.40 11/9/2017 -- -- 7.40 2/7/2018 -- -- 7.30 5/8/2018 -- -- 6.89 8/27/2018 -- -- 7.24 11/7/2018 -- -- 7.13 4/13/2020 0.64 -95.3 7.54 7/14/2020 0.38 -71.6 7.03 10/19/2020 0.29 -35.2 7.18 1/19/2021 0.31 -55.4 7.10 4/12/2021 0.22 -71.2 7.20 7/12/2021 0.29 -70.3 7.47 10/11/2021 0.13 -72.7 7.40 1/17/2022 0.48 -40.2 7.08 1/19/2022 0.49 -43.0 7.21 4/18/2022 0.51 -48.0 7.20 7/5/2022 0.24 -29.8 7.38 7/19/2023 0.29 -42.0 6.97 1365 - Downgradient 5/22/2013 -- -- 7.30 3/23/2015 -- -- 7.10 2/17/2016 -- -- 6.24 5/9/2016 -- -- 7.00 8/11/2016 -- -- 7.10 10/18/2016 -- -- 7.30 2/7/2017 -- -- 7.50 4/20/2017 -- -- 7.30 8/2/2017 -- -- 7.50 11/9/2017 -- -- 7.50 2/7/2018 -- -- 7.20 5/8/2018 -- -- 6.85 8/27/2018 -- -- 7.20 11/7/2018 -- -- 7.08 4/13/2020 0.63 -25.1 7.35 7/14/2020 0.32 -36.0 7.02 10/19/2020 0.21 -8.60 7.02

Page 14 of 15 Preparer: A. Anstaett, Date: 12/12/23 Table 2 - Redox Indicator Data, Field Parameters Reviewer: B. Lockwood Date: 12/15/23 BA1 Redox Evaluation Cimarron Remediation Site

Date DO ORP pH (mg/L) (mV) (SU) 1365 - Downgradient 1/18/2021 0.17 -24.9 7.20 4/12/2021 1.00 -30.7 7.20 7/12/2021 0.86 1.20 7.30 10/11/2021 0.18 -45.6 7.53 1/17/2022 0.11 35.8 7.22 1/19/2022 0.30 56.7 7.23 4/18/2022 0.81 3.80 7.20 7/5/2022 0.43 -3.90 7.21 7/19/2023 0.32 41.7 6.92 1363 - Downgradient 5/22/2013 -- -- 7.30 3/23/2015 -- -- 7.57 4/20/2017 -- -- 7.30 4/13/2020 2.05 47.4 7.40 7/13/2020 0.37 10.3 7.01 10/14/2020 0.27 31.4 7.08 1/18/2021 0.16 54.3 7.00 4/12/2021 1.39 161 7.00 7/12/2021 0.43 136 7.10 10/11/2021 0.40 126 7.27 1/17/2022 0.17 90.6 7.04 1/19/2022 0.37 96.4 7.14 4/18/2022 0.25 50.9 7.00 7/5/2022 0.44 48.7 7.10 7/19/2023 0.36 68.3 6.89

Page 15 of 15

FIGURES

FIGURE 1 REDOX ANALYSIS MONITORING WELLS BA1 REDOX EVALUATION REPORT EXTRACTION TEST WELL (INSTALLED) CIMARRON ENVIRONMENTAL INJECTION WELL (INSTALLED) RESPONSE TRUST

GROUNDWATER EXTRACTION TRENCH ^BURNS

.2? GETR-BA1-01 (INSTALLED)

O PROPOSED TREATED WATER INJECTION VVMSDONNELL. environmentalproperties management. Lie Pcc. TRENCH

Illo55 Baseman: GOOGLE EARTH 2019 Rev No: 0 N

60 120 PreDarer: BELOCKWOOD Date: 11/13/2023 Reviewer: EPULCHER Date: 11/20/2023 o SCALE IN FEET Coordinate System

N NAD 1983 2011 StatePlane Oklahoma North FIPS 3501 Ft US

r - ** r.,r' ill#

v 7 'i,

7

  • ' >>V3

o

ll

2: 15

  • 5'81m ____ _________LEGEND NOTES MCL-MAXIMUM CONCENTRATION LEVEL FIGURE 5 1' MONITOR WELL IN ALLUVIUM BURIAL AREA #1

<rc MONITOR WELL IN SANDSTONE B 1) ISOPLETH CONTOURS ARE DRAWN BASED ON REPRESENTATIVE URANIUM CONTOURS LU l ! MONITOR WELL IN SANDSTONE C "REPRESENTATIVE" URANIUM CONCENTRATIONS, BA1 REDOX EVALUATION REPORT C3c 2 MONITOR WELL IN TRANSITION ZONE EXPRESSED IN MICROGRAMS PER LITER (pg/L). CIMARRON ENVIRONMENTAL RESPONSE

LU, TRUST I GROUNDWATER EXTRACTION TRENCH 2) CONTOUR INTERVAL IS 200pg/L.

LU C2 ; GETR-BA1-01 (INSTALLED) ^BURNS

^.MCDONNELL, environmental

§s

  • URANIUM ANALYTICAL CONTOUR (pg/L) properties management, LLC i MCL (30 ljg/L) Basemap: GOOGLE EARTH 2019 Rev No: 0

-(S).zCD: 100 200 Preparer: BELOCKWOOD Date: 1/7/2024 Z> : SCALE IN FEET Reviewer: EPULCHER Date: 1/8/2024 CD

- Coordinate System CM -Sc NAD 1983 StatePlane Oklahoma North FIPS 3501 Feet Q2 2017 Q3 2018 Q3 2019 Q3 2020

'.Mj /.v)

Q3 2021 Q3 2022 LEGENDQ3 2023 MONITOR WELL IN ALLUVIUM MONITOR WELL IN SANDSTONE B MONITOR WELL IN SANDSTONE C MONITOR WELL IN TRANSITION ZONE GROUNDWATER EXTRACTION TRENCH GETR-BA1-01 (INSTALLED) SCALE IN FEET URANIUM ANALYTICAL CONTOUR (pg/L)

NOTES

1) WHERE DUPLICATE SAMPLES WERE COLLECTED, THE HIGHER OF THE TWO RESULTS WAS USED FOR CONTOURING EFFORTS.

FIGURE 6 BURNS TIME SERIES URANIUM ^MSDONNELL ISOCONCENTRATIONS BA1 REDOX EVALUATION REPORT CIMARRON ENVIRONMENTAL RESPONSE TRUST environmentalproperties management. ILC

Basemap: GOOGLE EARTH 2019 Rev No: 0 Preparer: BELOCKWOOD Date: 11/13/2023

ru ***

Reviewer: EPULCHER Date: 11/20/2023 Coordinate System APPENDIX A - BIOPOLYMER SLURRY DATA SHEET

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