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Environmental Properties Management, LLC - Tc-99 Groundwater Assessment Report
	ML20034D717
Person / Time
Site:	07000925
Issue date:	01/31/2020
From:	Lux J; Environmental Properties Management
To:	Davis P, Robert Evans, Kenneth Kalman; Document Control Desk, Office of Nuclear Material Safety and Safeguards, NRC Region 4, State of OK, Dept of Environmental Quality (DEQ)
References
	Download: ML20034D717 (42)
	v • d • e

9400 Ward Parkway

Kansas City, MO 64114 Tel: 405-642-5152

jlux@envpm.com January 31, 2020 Mr. Ken Kalman U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852-2738 Mr. Paul Davis Oklahoma Department of Environmental Quality 707 North Robinson Oklahoma City, OK 73101 Mr. Robert Evans U.S. Nuclear Regulatory Commission 1600 East Lamar Blvd; Suite 400 Arlington, TX 76011-4511 Re: Docket No.70-925; License No. SNM-928 Tc-99 Groundwater Assessment Report

Dear Sirs:

Solely as Trustee for the Cimarron Environmental Response Trust (CERT), Environmental Properties Management LLC (EPM) submits herein a technical memorandum discussing the assessment of technetium-99 (Tc-99) in groundwater at the Cimarron Site.

In 1996, the licensee at the time performed an investigation to identify the source of elevated beta concentrations in groundwater. Tc-99 was identified as a contaminant in groundwater as a result of that investigation, and analysis of groundwater samples (from specific locations) for Tc-99 was added to the annual environmental monitoring program.

A more expansive groundwater sampling effort, providing for analysis for Tc-99 was conducted in 2003; the results of that investigation were reported in Draft Technitium-99 Groundwater Assessment Report1. The purpose of that groundwater assessment was to identify the maximum concentration of Tc-99 in groundwater to determine whether groundwater remediation was required to reduce the concentration of Tc-99 in groundwater. As a result of that assessment, the NRC agreed that the decommissioning plan would not need to provide for the remediation of Tc-

99.

Analysis of groundwater samples for Tc-99 was removed from the annual environmental monitoring program in 2009. In 2012, the NRC and EPM split groundwater samples from four locations for independent analysis for Tc-99. In a letter dated April 22, 2013, the NRC formalized its decision that Tc-99 will not have to be addressed in the groundwater remediation 1 Chase Environmental Group, December 2003

Mr. Ken Kalman, et. al.

U.S. Nuclear Regulatory Commission January 31, 2020 Page 2 plan. That letter did require that analysis of groundwater samples for Tc-99 be included in the post-remediation monitoring program.

In 2019, it was determined that, regardless of whether remediation plans for groundwater need to provide for the removal of Tc-99 from groundwater, Tc-99 will nevertheless be recovered in groundwater and be discharged to surface water and/or captured by ion exchange resin or bioreactor solids. A relatively comprehensive assessment of Tc-99 concentrations in groundwater was needed to enable groundwater remediation design personnel to estimate the concentration of Tc-99 that will be in the influent to the groundwater treatment system.

Therefore, data needed to be obtained for all the remediation areas from which groundwater will be recovered for treatment.

EPM retained Burns & McDonnell to evaluate Tc-99 based on the planned treatment process, employing the same methodology to estimate the concentration of Tc-99 in influent to the treatment system that was used for uranium and nitrate. The data set obtained during the 2019 sampling event is the only data set that provides sufficient quality data for wells located in all remediation areas. Consequently, instead of calculating representative concentrations for Tc-99 at each monitor well, the results obtained from the 2019 samples was considered the representative concentrations.

EPM had previously notified the NRC and the DEQ that based on historic data, the initial concentration of Tc-99 in the influent to the treatment system was estimated to be 446 picoCuries per liter (pCi/L). 446 pCi/L is slightly over half of the primary drinking water standard of 900 pCi/L. Using this more robust data set, the initial concentration of Tc-99 in the influent to the treatment system is now estimated to be approximately 102 pCi/L, or approximately 11% of the primary drinking water standard.

As previously discussed with the NRC and the DEQ, even if groundwater treatment systems did not remove any Tc-99 from recovered groundwater, the concentration of Tc-99 in the influent is so low that the water could be reinjected and/or discharged with no impact to State permits.

However, it is possible that the ion exchange resin will remove most if not all of the Tc-99 from the groundwater, and the biomass generated by the biodenitrification process may remove some if not all of the Tc-99 in the influent coming from the ion exchange system to the nitrate treatment system.

In addition, analytical results for some historic samples included estimated Tc-99 concentrations exceeding 200 picoCuries per liter (pCi/L) in the eastern portion (Burial Area #1) of the site, but the detection limit in the database was 300 pCi/L. Because the source of Tc-99 to groundwater

Mr. Ken Kalman, et. al.

U.S. Nuclear Regulatory Commission January 31, 2020 Page 3 was the liquid waste streams sent to Uranium Ponds #1 and #2, Tc-99 should not be present in groundwater migrating from Burial Area #1. Therefore, additional samples were collected from monitor wells in Burial Area #1 during the 2019 sampling event to definitively determine whether Tc-99 is present in groundwater in this portion of the site.

Tc-99 was not detected in any of the 13 samples collected from monitor wells in Burial Area #1 during the 2019 monitoring event. This conclusively demonstrates that Tc-99 is not present in groundwater in Burial Area #1.

If you have questions or comments related to this Tc-99 groundwater assessment memorandum, please contact me at 405-641-5152 or at jlux@envpm.com.

Sincerely, Jeff Lux, P.E.

Trustee Project Manager Attachment cc: Michael Broderick, Oklahoma Department of Environmental Quality (electronic copy only)

NRC Public Document Room (electronic copy only)

ATTACHMENT 1 BURNS & McDONNELL ENGINEERING COMPANY TECHNICAL MEMORANDUM BMCD-GWREMED-TM005 TECHNITIUM-99 GROUNDWATER ASSESSMENT

Memorandum Document No.: BMCD-GWREMED-TM005 Revision: A Date:

To:

From:

January 30, 2020 Jeff Lux, EPM John Hesemann, Burns & McDonnell Emily Ahlemeyer, Burns & McDonnell

Subject:

Technetium-99 Groundwater Assessment BURNS ~

£DONNELL This Technetium-99 Groundwater Assessment has been developed to support remediation design activities and the potential revision of a Decommissioning Plan (D-Plan) for the Cimarron Environmental Response Trust (CERT) remediation project at the Cimarron Site located in Guthrie, Oklahoma (Site). The technetium-99 (Tc-99) groundwater concentration data required to conduct this assessment were obtained during a sampling event conducted in 2019. These data were used to assess the nature and extent of Tc-99 in groundwater at the Site, and to estimate influent Tc-99 concentrations for the Western Area (WA) groundwater treatment system planned for the Site. During the 2019 monitoring event, Tc-99 was not detected in any groundwater samples collected in Burial Area 1 (BAl) at the Site. As a result, BAl is not discussed in the evaluation presented herein.

The methods used to evaluate the distribution of Tc-99 in WA groundwater and estimate influent Tc-99 concentrations for the WA Treatment Facility (W ATF) were similar to those previously used to evaluate contaminant distribution and influent concentrations for uranium, nitrate, and fluoride, as described in the 2018 Basis of Design for Groundwater Remediation Technical Memorandum (2018 Basis of Design). 1 The 2019 Tc-99 groundwater analytical results are considered "representative concentrations" for the purposes of this evaluation. The historical Tc-99 groundwater dataset was not used in this evaluation due to issues related the quality, quantity, and distribution of the data.

1.0 Tc-99 Groundwater Data Review A review of laboratory analytical results for groundwater samples collected during monitoring events conducted in 2019 was performed in accordance with the United States Environmental Protection Agency's National Functional Guidelines for Inorganics Superfund Methods Data 1 Burns & McDonnell Engineering Company, Inc. (2018). Basis of Design for Groundwater Remediation (BMCD-GWREMED-TMOOl Rev. C). Kansas City: Hesemann.

Memorandum (co t 1 ~

January 30, 2020 Page 2 of 10 BURNS ~

!:DONNELL Review. 2 The review was performed to assess the validity of the laboratory data. Tc-99 activity concentration data were rejected as a result of the analytical data review for the following WA monitor wells: T-79, 1348, 1395, 1396, 1337, and 1319B-2. Tc-99 activity concentration data were rejected for the following BAl monitor wells: 1314, TMW-08, 02W06, 02W 44, TMW-13, and TMW-24. The Tc-99 activity concentration result was also rejected for th~ surface water sample 1201 (Upstream). The primary cause for the rejection ofTc-99 activity concentration data was a negative activity concentration result; Tc-99 concentrations cannot be negative. All rejected data were qualified as not detected above the minimum detectable concentration (MDC).

The Tc-99 activity concentration data are included as Attachment 1.0.

The Tc-99 activity concentrations were converted to mass concentrations using specific activity to maintain consistency with the tables and figures presented in the 2018 Basis of Design. 1 The specific activity of Tc-99 is 0.017 curies per gram (Ci/g), equivalent to 0.059 nanograms per picocurie (ng/pCi). 3 2.0 Tc-99 Isopleth Map Generation Uranium, nitrate, and fluoride isopleth groundwater concentration plots for the BAl and WA remediation areas were previously generated using the Surfer software app1ication developed by Golden Software. 1 Due to limitations in the spatial distribution of Tc-99 groundwater data in the WA, Surfer was not used to develop the Tc-99 isopleth maps.

The Tc-99 isopleths were manually created using concentration data obtained from WA groundwater sample results, knowledge of historical site features (i.e., storage ponds, drainage channels, topography, etc.), and observed groundwater flow direction. Tc-99 groundwater concentrations for wells screened within Sandstone A (SSA) were used to develop a formation-specific isopleth map. Groundwater concentrations for wells screened within Sandstone B (SSB),

transition zone, and alluvial formations were used to develop a separate Tc-99 isopleth map for the hydrostratigraphic unit comprised of these three aquifer formations. Copies of the WA isopleth maps are included as Attachment 2.0.

2 United States Environmental Protection Agency. (2017). National Functional Guidelines for Inorganics Superfund Methods Data Revfow (EPA-540-R-201 7-001). Office of Superfund Remediation and Technology Innovation.

Washington, DC.

3 49 C.F.R. § 173.435 Table of Al and A2 Values for Radionuclides.

Memorandum con 1 January 30, 2020 Page 3 of 10 BURNS ~

£DONNELL 3.0 Remediation Area and Pore Volume Estimates The WA consists of 11 individual remediation areas: W AA-BLUFF, WAA-EAST, W AA-WEST, WAA U>DCGL, 1206-NORTH, WU-1348, WU-PBA, WU-BA3, WU-UPI, WU-UP2-SSA, and WU-UP2-SSB (see figures provided in Attachment 3.0). Remediation areas were established based on uranium, nitrate, and fluoride concentrations and zones of hydraulic influence associated with groundwater extraction or treated water injection. Zones of hydraulic influence for remediation extraction and injection components were established by particle tracking analyses conducted using the 2018 groundwater flow model, as discussed in the 2018 Basis of Design. 1 Pore volume, calculated by multiplying the aquifer volume targeted for remediation by effective porosity, is one of the input parameters required for estimating Tc-99 influent concentrations over the course of WA TF operation. As described in the 2018 Basis of Design, the targeted aquifer volume was calculated, for most remediation areas, by multiplying the lateral extent of each remediation area by saturated thickness. Three-dimensional visualization (3DV) modeling was used to calculate the aquifer volume for remediation areas with variable saturated thicknesses, as discussed in the 2018 Basis of Design. 1 Depending on the location, the remediation areas were developed based on:

The extent of the extraction component(s) approximate hydraulic capture zone within which uranium concentrations are at or above 30 µg/L and-for WA areas only-nitrate concentrations are at or above 10 mg/L; and/or The approximate hydraulic zone of influence associated with injection component(s).

Tc-99 concentrations were not considered in remediation area development because Tc-99 is not being targeted for remediation at the Site. In addition, the Tc-99 remediation impacts delineated by the 10 nanogram per liter (ng/L) isopleths presented on the maps included in Attachment 2.0 are contained within the original remediation areas. Consequently, the remediation areas described in the 2018 Basis of Design, and the corresponding calculated pore volumes, were not altered for the purposes of estimating Tc-99 influent concentrations over the course of WATF operation.

4.0 Area-Weighted Influent Tc-99 Concentration Estimates Figures included in Attachment 3.0 illustrate the remediation areas described in Section 3.0, the remediation component locations, and the extent of Tc-99 groundwater impacts. As shown in.0A, Tc-99 groundwater impacts in SSA are limited to a portion of the WU-UPI

Memorand January 30, 2020 Page 4 of 10 BURNS ~

£D0NNELL remediation area and a portion of the WU-UP2-SSA remediation area. As shown in Attachment 3.0B, Tc-99 groundwater impacts within the hydrostratigraphic unit comprised of SSB, transition zone, and alluvium formations are limited to the WU-UP2-SSB remediation area, portions of the WAA-BLUFF and WAA U>DCGL remediation areas, and portions of the SSB formation underlying the WU-UPI and WU-UP2-SSA remediation area.

Tc-99 concentrations in groundwater recovered by some groundwater extraction components are expected to increase after remediation begins in the WA, as groundwater with higher Tc-99 concentrations is drawn toward extraction components. Tc-99 concentrations are expected to increase above the initial concentration for the following components:

GE-W AA this alluvial extraction well is currently located outside the extent of Tc-99 impacts; however, this well is expected to capture a portion of the SSB-transition zone-alluvium Tc-99 plume (see Attachment 3.0B). For influent concentration modeling purposes, the Tc-99 concentration at this well is assumed to increase from Oto 11 ng/L, based on the area-weighted concentration averaging described below.

GE-W AA the estimated initial Tc-99 concentration at this well is 14 ng/L; however, the Tc-99 concentration at this well is expected to increase as higher concentrations within the SSB-transition zone-alluvium Tc-99 plume, located to the southwest, are drawn toward this well (see Attachment 3.0B). For influent concentration modeling purposes, the Tc-99 concentration at this well is assumed to increase to approximately 23.94 ng/L, based on the area-weighted concentration averaging described below.

The future Tc-99 concentration increases for the wells listed above were estimated by conducting incremental, area-weighted concentration averaging within the SSB-transition zone-alluvium Tc-99 plume areas captured by the respective extraction components. The resulting area-weighted average concentrations were then used to represent future Tc-99 concentration increases at GE-W AA-03 and GE-W AA-11. The results of SSB-transition zone-alluvium Tc-99 plume concentration averaging were also used to calculate future maximum Tc-99 concentrations for other extraction wells expected to capture Tc-99 impacted groundwater (i.e., GE-W AA-06 through GE-W AA-I 0). The future maximum Tc-99 concentrations for these wells do not exceed the respectjve initial concentrations; however, they were used in the WATF influent Tc-99 concentration flow rate-weighted averaging and concentration decay modeling described in Section 5.0.

Area-weighted concentration averaging was also conducted for the SSA plume in the WU-UPI and WU-UP2-SSA remediation areas located upgradient ofGE-WAA-03 and GE-WAA-06

Memorandum (cont1 January 30, 2020 Page 5 of 10 BURNS ~

!:DONNELL

, through GE-WAA-11. However, the resulting concentrations were less than those calculated for the SSB-transition zone-alluvium plume areas; therefore, area-weighted average concentrations for the SSA plume were not used in the WATF influent Tc-99 concentration flow rate-weighted averaging and concentration decay modeling described in Section 5.0.

The areas developed for concentration averaging within the SSA and SSB-transition zone-alluvium Tc-99 plumes are illustrated on figures included in Attachment 4.0. As shown on these figures (Attachments 4.0A and 4.0B) and the area-weighted averaging results presented in.0C, Tc-99 isopleths developed for SSA and SSB-transition zone-alluvium Tc-99 plumes (see Section 2.0) were used to conduct the area-weighted concentration averaging. For

-GE-WAA-03 and GE-WAA-06 through GE-WAA-11, future maximum Tc-99 concentrations were estimated by conducting area-weighted concentration averaging within the approximate SSB-transition zone-alluvium extraction capture zones for these wells (see Attachment 4.0B and 4.0C).

Results from the area-weighted averaging analysis completed for each applicable remediation area and groundwater extraction component are presented in Attachment 4.0C. Calculation files in native (MS Excel) format can be provided to facilitate review of calculation methods (i.e.,

formulas, references, inputs, etc.) by Nuclear Regulatory Commission (NRC) and Oklahoma Department of Environmental Quality (DEQ) personnel.

5.0 Tc-99 Influent Concentration Estimates The estimated concentration of Tc-99 in W ATF influent was calculated to support treatment system design and assess the impact of Tc-99 on treatment process waste characteristics. A detailed description of the processes used to estimate treatment system influent Tc-99 concentrations is provided below.

5.1 As discussed in Section 4.0, future maximum Tc-99 influent concentrations are anticipated to be higher than initial concentrations for wells GE-W AA-03 and GE-W AA-11, while future maximum Tc-99 influent concentrations are anticipated to be lower than initial concentrations for all other wells capturing Tc-99-impacted groundwater (GE-WAA-06 through GE-WAA-10). Because Tc-99 concentrations are expected to increase in groundwater captured by extraction wells located in both groundwater extraction areas impacted by Tc-99 (GE-WAA-11 in the WAA-BLUFF area and GE-WAA-03 in the W AA U>DCGL area), initial (i.e., time zero) influent Tc-99 concentrations (Co) and future maximum (i.e., time "t") influent Tc-99 concentrations (Ct) were estimated for each groundwater extraction component located in these areas.

Memo and m January 30, 2020 Page 6 of 10 BURNS ~

£DONNELL The Co Tc-99 concentration for each extraction component was estimated by manual concentration isopleth interpolation using the isopleth maps (see Section 2.0). Area-weighted concentration averaging (see Section 4.0) was used to calculate the Ct concentration that will occur following remediation startup at extraction wells capturing Tc-99-impacted groundwater (GE-WAA-03 and GE-WAA-06 through GE-WAA-11).

The area-weighted concentration averaging result for the GE-W AA-09 through GE-W AA-11 capture zone within the SSB/transition zone/alluvium hydrostratigraphic unit (23.94 ng/L-see Attachment 4.0C) was applied as the Ct for extraction wells GE-WAA-09 through GE-WAA-11. The area-weighted concentration averaging result for the GE-W AA-06 through GE-W AA-08 capture zone within the SSB/transition zone/alluvium hydrostratigraphic unit (9.58 ng/L - see Attachment 4.0C) was applied as the Ct for extraction wells GE-W AA-06 through GE-W AA-08. The area-weighted concentration averaging result for the GE-W AA-03 capture zone within the SSB/transition zone/alluvium hydrostratigraphic unit (11.0 ng/L - see Attachment 4.0C) was applied as the Ct for extraction well GE-WAA-03. The Co and Ct influent Tc-99 concentrations are summarized for each WAA-BLUFF and WAA U>DCGL groundwater extraction component in Attachment 5.1. Calculation files in native (MS Excel) format can be provided to facilitate review of calculation methods (i.e., formulas, references, inputs, etc.) by NRC and DEQ personnel.

5.2 Results of the particle tracking analysis presented in Attachment 4.0B were used to estimate the time (i.e., time "t") at which Ct concentrations would occur at W AA-BLUFF and W AA U>DCGL extraction wells capturing Tc-99-impacted groundwater (GE-W AA-03 and GE-WAA-06 through GE-WAA-11, respectively). Based on the particle tracking results, the estimated time required for groundwater with elevated Tc-99 concentrations currently located in the WU-UP2-SSB remediation area to reach GE-W AA-11 is approximately 365 days; consequently, future maximum Tc-99 groundwater concentrations were assumed occur in the W AA-BLUFF extraction well influent approximately 1 year (365 days) following remediation startup. The estimated time required for the western edge ofTc-99 plume located in the W AA-BLUFF remediation area to reach GE-W AA-03 is approximately 120 days (see Attachment 4.0B);

consequently, future maximum Tc-99 groundwater concentrations were assumed to occur in the W AA U> DCGL extraction well influent approximately 4 months (120 days) following remediation startup. Estimated time "t" values are presented for the W AA-BLUFF and WAA U>DCGL remediation areas in Attachment 5.1.

Memorandum January 30, 2020 Page 7 of 10 BURNS ~

£DONNELL 5.3 Following calculation of Co and Ct Tc-99 influent concentrations for individual extraction components, and the estimation of time "t" for WAA-BLUFF and WAA U>DCGL remediation areas, flow rate-weighted averaging was used to calculate the estimated Co and Ct influent concentrations for each remediation area (i.e., influent treatment stream).

The estimated Co and Ct flow rate-weighted average Tc-99 influent concentrations for the W AA U>DCGL remediation area are 0.0 and 2.7 ng/L, respectively (see Attachment 5.1). The estimated Co and Ct flow rate-weighted average Tc-99 influent concentrations for the WAA-BLUFF remediation area are 14.5 and 12.8 ng/L, respectively. Although Ct is less than Co for the W AA-BLUFF influent, Ct is greater than the WAA-BLUFF influent concentration after 365 days of W ATF operations, based on 365 days of decay from Co. Therefore, the W AA-BLUFF Ct concentration represents an increase in the influent Tc-99 concentration at 365 days. The Tc-99 Co and Ct for the W AA-BLUFF and W AA U> DCGL influent treatment streams are summarized in Attachment 5.1. The concentration decay function and model results are discussed below in Sections 5.4 and 5.5, respectively.

5.4 A first-order kinetic sorption equation was used to model the decline in Tc-99 concentration for influent streams associated with each remediation area contributing to the combined W ATF influent. The estimated/calculated Tc-99 Co and Ct values, and the time "t" values for the W AA-BLUFF and W AA U>DCGL influent treatment streams were used to model the concentration decline for those remediation areas, while a O. 0 ng/L Tc-99 influent concentration was assumed throughout the W ATF operational timeframe for the five WA remediation areas that will not capture Tc-99 impact.ed groundwater (see Attachment 5.1). The aquifer retardation parameters used in the kinetic sorption equation to predict declining Tc-99 influent concentrations for the W ATF are summarized in Attachment 5.4.

5.5 A flow rate-weighted average of the combined W ATF influent stream was calculated for each concentration decay time interval (i.e., month of operation) to model the decline in WA TF Tc-99 influent concentration over the operational life of the system. The results of the WA analysis are presented in Attachment 5.5. In addition, calculation files in native (MS Excel) format can be provided to facilitate review of calculation methods (i.e.,

formulas, references, inputs, etc.) by NRC and DEQ personnel.

5.6 The combined WATF influent Tc-99 concentration at the time of system startup was calculated to be 6.04 ng/L (equivalent to 102.6 picocuries per liter [pCi/L]). The concentration is projected to decrease to 5.06 ng/L (equivalent to 86.1 pCi/L after 4

Me orandum (c n I r, January 30, 2020 Page 8 of 10 BURNS ~

£DONNELL months of operation, at which time the concentration is projected to increase to 5.90 ng/L (equivalent to 100.3 pCi/L) as a result of Tc-99 impacted groundwater arriving at GE-W AA-03. From Month 5 through Month 12, the influent Tc-99 concentration then decreases to 4.14 ng/L (equivalent to 70.3 pCi/L), at which time the concentration increases to 5.85 ng/L (equivalent to 99.5 pCi/L) as a result of increasing Tc-99 concentrations in the groundwater captured by GE-W AA-06 through GE-W AA-11.

Concentration reductions resume following this increase and the concentration falls below 1 pCi/L (equivalent to 0.06 ng/L) after 116 months of operation. The time series concentration decline analys~s for each WA remediation area influent stream was concluded in the month in which uranium and nitrate remediation criteria are predicted to be achieved, as determined by previous remediation duration estimate calculations. 1 At the conclusion of remediation operations, following 150 months of operation, the combined influent concentration is expected to have decreased to 0.01 ng/L (equivalent to 0.22 pCi/L).

6.0 Limitations and Assumptions Associated with Concentration Estimates The accuracy of the Tc-99 groundwater concentration estimates presented above are potentially limited by the quantity of available data, subsurface heterogeneity, variability in the concentration and distribution of contaminants in the aquifer units targeted for remediation, and other factors. In developing this assessment, Bums & McDonnell and EPM consistently applied reasonably conservative assumptions to minimize the potential for Tc-99 concentrations to be underestimated. This in tum reduced the probability that long-term remediation costs would be underestimated. These assumptions included the following:

As discussed above in Section 5.0, the larger of the following concentration values were used as the future maximum groundwater concentration for the purposes of modeling the concentration decay over time:

o The area-weighted Tc-99 concentration average over the Sandstone A formation ( determined as described in Section 4.0) o The area-weighted Tc-99 concentration average over the Sandstone B, transition zone, and alluvium formations ( determined as described in Section 4.0)

As discussed in the 2018 Basis of Design, conservatively high bulk soil density, distribution coefficient (Kct), and saturated thickness values were applied in retardation parameter estimates.

1 The methods used to model the concentration decline analysis assume Tc-99 is evenly distributed throughout the entire saturated thickness of each remediation area.

Me or ndum c t 1 ~

BURNS ~

£D0NNELL January 30, 2020 Page 9 of 10 7.0 Conclusions and Recommendations The following conclusions and recommendations were provided as a result of the assessment presented herein:

Sampling and analysis for Tc-99 performed in 2019 verified that Tc-99 is not present in BAl groundwater.

Sampling and analysis for Tc-99 performed in 2019 provided sufficient information to estimate initial and maximum Tc-99 concentrations in the influent to the WATF.

The estimated Tc-99 concentration in the combined WATF influent at the time of remediation system startup is 6.04 ng/L ( equivalent to 102.6 pCi/L ). The influent Tc-99 concentration is not projected to increase above this initial concentration during system operations.

Tc-99 was not detected outside of areas addressed by the existing groundwater remediation design; therefore, no revision to the groundwater remediation design is necessary.

The concentration ofTc-99 in the influent to the WATF is not expected to approach the drinking water standard; therefore, no revision to the groundwater treatment system is necessary.

A concentration decline analysis for monitor wells exceeding the EPA drinking water criterion was not completed, based on the following:

o Tc-99 concentrations exceeded the EPA drinking water criterion at only three out of 3 5 monitor wells sampled.

o Tc-99 concentrations exceeded the EPA drinking water criterion by less than 10% at 2 of the 3 wells exhibiting exceedances.

Although Tc-99 will not impact the groundwater treatment system design, it may accumulate in water treatment media or wastes and impact treatment system operations ( e.g., disposition of resin or waste).

Attachments:.0 - Tc-99 Data Table.0 - Tc-99 Isopleth Maps.0-Remediation Component Locations.0-Area-Weighted Averaging Boundaries and Results

Memorandum c t 1d January 30, 2020 Page 10 of 10 BURNS ~

£DONNELL.1 - Initial Influent Tc-99 *concentrations.4 - Tc-99 Retardation Parameters.5 - Influent Concentration Decline Analysis

.0 - Tc-99 Data Table

.0 Tc-99 Data Table Cimarron Remediation Site Technetium-99 Activity and Mass Concentration Results Activity Area Location ID Collection Concentration Date (pCi/L)

T-62 812612019 80.1 WAA T-64 812612019 24.4 U>DCGL T-76 812612019 101 T-79 812612019

-1.59 I

WAA-IT-97 19/3/2019 I

24.8 WEST T-54 91312019 567 T-55 91312019 341 T-56 91312019 45.6 WAA-T-57 91312019 185 BLUFF T-58 91312019 368 T-63 91312019 272 T-86 91312019 57.5 T-87 91312019 175 WAA-T-59 91312019 15.2 EAST T-60 91312019 46.4 T-90 91312019 19.5 WU-1348 91412019

-6.01 1348 1312 91412019 662 WU-1313 91412019 251 UP1 1313DUP 91412019 299 1395 91412019

-16.5 1396 91412019

-9.17 1336A 91412019 982 1336ADUP 91412019 963 1337 91412019

-13.4 1346 91512019 1650 WU-1346DUP 91512019 1600 UP2 1347 91412019 4.98 1387 91412019 23.5 1389 91412019 35.4 1401 91512019 705 1402 91512019 941 1351 812612019 28.2 WU-1351DUP 812612019 13.2 BA3 1352 812612019 12.3 1356 812612019 51.4 WU-1319B-1 91412019 5.26 PBA 1319B-2 91412019

-9.58 I

Mass Concentration Uncertainty (ng/L) 1,2 (pCi/L) 4.7 30.9 1.4 23 5.9 27.3 NIA 22.1 1.5 I

24.5 33.4 43.8 20.1 35.2 2.7 26.4 10.9 33.7 21.6 36.4 16.0 34.1 3.4 26.3 10.3 31 0.9 25.6 2.7 25.7 1.1 25.1 NIA 26.8 38.9 40.8 14.8 32.4 17.6 32.1 NIA 25.1 NIA 25.8 57.8 48.1 56.6 48.5 NIA 22.8 97.1 59.4 94.1 58.3 0.3 24.7 1.4 25.5 2.1 24.6 41.5 44.5 55.4 49.8 1.7 23.5 0.8 23 0.7 22.2 3.0 24.1 0.3 25.2 NIA 22.9 Lab or Data Review Qual u

U R I

u I

u u

U, R U, R U R U, R u

u u

U R Rev.A 1/30/2020 MDC (pCi/L) 48.7 38.3 41.3 38.5 41 I

47.8 43 43.1 47.8 43.6 44.2 42.1 43.7 43.5 41.8 42.4 46.9 40 42.4 39.5 44.7 45.4 40.7 41.7 40.6 40.9 40.5 42.7 42.9 40.4 43.6 44.1 39.1 39.2 37.7 38.7 43.5 40.5 Page 1 of 2

.0 Tc-99 Data Table Cimarron Remediation Site Technetium-99 Activity and Mass Concentration Results Activity Area Location ID Collection Concentration Date (pCi/L) 1206-MWWA-03 8/27/2019 11.4 NORTH MWWA-09 8/27/2019 46 1201 8/27/2019

-1.8 SURFACE (Upstream)

WATER 1202 8/27/2019 2.27 (Downstream) 1314 8/27/2019

-5.81 1315R 9/5/2019 23 BA1-A TMW-08 8/28/2019

-4 TMW-09 8/28/2019 12.5 TMW-09DUP 8/28/2019

-8.09 02W06 8/27/2019

-5.14 02W08 8/28/2019 6.17 02W19 9/5/2019 11.2 BA1-B 02W44 8/28/2019

-3.96 1363 9/5/2019 4

TMW-13 8/28/2019

-4.22 TMW-24 9/5/2019

-17.2 Notes:

Mass Concentration Uncertainty (ng/L)1,2 (pCi/L) 0.7 22.8 2.7 24.7 N/A 22.5 0.1 27.3 N/A 21.5 1.4 24.4 N/A 22.4 0.7 22.2 N/A 23.5 N/A 21.2 0.4 21.7 0.7 22.8 N/A 23.6 0.2 23.8 N/A 21.2 N/A 22 Lab or Data Review Qual u

U, R u

U R U, R u

u U, R u

U, R U R Rev.A 1/30/2020 MDC (pCi/L) 38.9 40 39.2 47.3 37.7 40.9 39.1 37.7 41.3 37.2 37.3 38.9 41.2 41.2 37.2 39.4 1Activity to mass conversion factorforTc-99 is 1.7E-02 Ci/g (17 pCi/ng) [49 CFR 173.435 Table of A1 and A2 values for radionuclides].

2An results qualified with a U were adjusted to the MDC of 50 pCi/L (2.9 ng/L) in subsequent assessments.

~--~ Tc-99 exceeds 900 pCi/L (MCL)

Red bold font indicates qualifier was added during internal data validation Qualifier Definitions:

J - Qualified as estimated during the data evaluation R - Rejected during the reasonableness review U - Analyte not detected above the minimum detectable concentration (MDC)

MDC - Minimum Detectable Concentration pCi/L - PicoCuries per liter ng/L - Nanograms per liter Page 2 of 2

.0 - Tc-99 Isopleth Maps

ATTACHMENT 2.0A Tc-99 ISOPLETH IN THE WESTERN AREA SANDSTONE A Tc-99 GROUNDWATER ASSESSMENT MEMO CIMARRON SITE, OKLAHOMA

~ BURNS

'-'-.MSDONNELL.

CR EA T E AMAZl~I G.

~

environmental proporticsman.:igemont. LLC SANDSTONE A MONITOR WELL EXTRACTION WELL INJECTION WELL EXTRACTION TRENCH INJECTION TRENCH US EPA Tc-99 CONCENTRATION LIMIT OF 52.9 ng/L (900 pCi/L) 10 ng/L (170 pCi/L)

CJ 20 ng/L (340 pCi/L) c:::J 30 ng/L (510 pCi/L) c:=J 40 ng/L (680 pCi/L) c:::J 50 ng/L (850 pCi/L)

NOTES

1. AERIAL IMAGE MOSAICKED USING GOOGLE EARTH 2017 AERIAL PHOTOS.

2. SOME CONCENTRATIONS EXCEEDED THE US EPA ACTIVITY CONCENTRATION LIMIT OF 900 pCi/L (52.9 ng/L):1336a - 56.9 ng/LAND 1402 - 54.52 ng/L.

NO CONCENTRATIONS EXCEEDED THE NRC Tc-99 ACTIVITY CONCENTRATION LIMIT OF 3,790 pCi/L (222.9 ng/L).

0 250 500

GE-WAA-06 0

ATTACHMENT 2.08 Tc-99 ISOPLETH IN THE WESTERN AREA SANDSTONE B, TRANSITION ZONE, ALLUVIUM Tc-99 GROUNDWATER ASSESSMENT MEMO CIMARRON SITE, OKLAHOMA

~ BURNS

'-'-MS DONNELL CREATE AMAZ I NG.

~

environmental proportic~ management. LLC ALLUVIUM MONITOR WELL

+ SANDSTONE 8 MONITOR WELL

+ TRANSITION ZONE MONITOR WELL 0

EXTRACTION WELL e

INJECTION WELL EXTRACTION TRENCH r -

US EPA Tc-99 CONCENTRATION LIMIT OF 52.9

.a ng/L (900 pCi/L) 10 ng/L (170 pCi/L) 20 ng/L (340 pCi/L) 30 ng/L (510 pCi/L) 40 ng/L (680 pCi/L) 50 ng/L (850 pCi/L) 60 ng/L (1020 pCi/L) 70 ng/L (1190 pCi/L) 80 ng/L (1360 pCi/L) 90 ng/L (1530 pCi/L)

NOTES

1. AERIAL IMAGE MOSAICKED USING GOOGLE EARTH 2017 AERIAL PHOTOS.

2. SOME CONCENTRATIONS EXCEEDED THE US EPA ACTIVITY CONCENTRATION LIMIT OF 900 pCi/L (52.9 ng/L): 1346 - 95.6 ng/L.

NO CONCENTRATIONS EXCEEDED THE NRC Tc-99 ACTIVITY CONCENTRATION LIMIT OF 3,790 pCi/L (222.9 ng/L).

0 250 500

.0 - Remediation Component Locations

GE-WAA-15 0

GE~WAAAl:4 0

+

GE-A-02 0

+

ATIACHMENT 3.0A REMEDIATION COMPONENT LOCATIONS SANDSTONE A Tc-99 CONTOURS Tc-99 GROUNDWATER ASSESSMENT MEMO CIMARRON SITE, OKLAHOMA

~ BURNS

'-'-M£DONNELL.

~

CREA T E AMAZ I N L; environmental ciropotie-: n\\11:19-:1rfa1 llC LEGEND 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 WELL e

INJECTION WELL EXTRACTION TRENCH INJECTION TRENCH

-- INJECTION PIPING EXTRACTION PIPING r - I US EPA Tc-99 CONCENTRATION LIMIT OF 52.9 ng/L (900 pCi/L)

WAAU>DCGL 1206-NORTH WU-PBA WU-UP1 WU-1348 D

WU-UP2-SSA D

WU-UP2-SS8 D

10 ng/L (170 pCi/L)

D 20 ng/L (340 pCi/L)

D 30 ng/L (510 pCi/L)

CJ 40 ng/L (680 pCi/L) 50 ng/L (850 pCi/L)

NOTES

1. AERIAL IMAGE MOSAICKED USING GOOGLE EARTH 2017 AERIAL PHOTOS.

2. GROUNDWATER TREATMENT STRUCTURES ARE FROM THE 90% DESIGN.

0 375 750

5 7 u GE-WAA-04 0

GE-WAA-14 0

GE-WAA-15 0

ATIACHMENT 3.08 REMEDIATION COMPONENT LOCATIONS SANDSTONE B, TRANSITION ZONE, ALLUVIUM Tc-99 CONTOURS Tc-99 GROUNDWATER ASSESSMENT MEMO CIMARRON SITE, OKLAHOMA

~ BURNS

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~

environmental CREAT E AM A ZIN G.

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LEGEND

+

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 WELL INJECTION WELL EXTRACTION TRENCH INJECTION TRENCH INJECTION PIPING EXTRACTION PIPING

~

TREATMENT FACILITY AREA r -

I US EPA Tc-99 CONCENTRATION LIMIT OF 52.9 ng/L (900 pCi/L)

WM-BLUFF D

WM-EAST WM-WEST D

WMU>DCGL 1206-NORTH WU-PBA WU-UP1 WU-1348 D

WU-UP2-SSA D

WU-UP2-SSB 10 ng/L (170 pCi/L) 20 ng/L (340 pCi/L) 30 ng/L (510 pCi/L) 40 ng/L (680 pCi/L) 50 ng/L (850 pCi/L) 60 ng/L (1020 pCi/L) 70 ng/L (1190 pCi/L) 80 ng/L (1360 pCi/L) 90 ng/L (1530 pCi/L)

1. AERIAL IMAGE MOSAICKED USING GOOGLE EARTH 2017 AERIAL PHOTOS.

2. GROUNDWATER TREATMENT STRUCTURES ARE FROM THE 90% DESIGN.

0 375 750

.0 -

Area-Weighted Averaging Boundaries and Results

5

,. u

.J

.J LJ

~,.

5

i J

~

2 J

0

i

,J

i

,J

~

[

9 2

L

)

ATIACHMENT 4.0A AREA-WEIGHTED AVERAGING BOUNDARIES AND RESULTS SANDSTONE A Tc-99 GROUNDWATER ASSESSMENT MEMO CIMARRON SITE, OKLAHOMA

~

~ BURNS

'-.'-.M~DONNELL, environmental CR EA T E AMAZ I NG proportiusmanagemont.LLC LEGEND

+

SANDSTONE A MONITOR WELL 0

EXTRACTION WELL e

INJECTION WELL EXTRACTION TRENCH INJECTION TRENCH REVERSE PARTICLE TRACKING

< REVERSE PARTICLE TRACKING ARROWS r --.

US EPA Tc-99 CONCENTRATION LIMIT OF 52.9 ng/L (900 pCi/L) r--"I AWCA BOUNDARY FOR GE-WAA-03 & GE-

..._. WAA-06 TO GE-WAA-08 r--"I AWCA BOUNDARY FOR GE-WAA-09 TO GE-

....._. WAA-11 D

10 ng/L (170 pCi/L)

D 20 ng/L (340 pCi/L)

D 30 ng/L (51 O pCi/L)

D 40 ng/L (680 pCi/L)

D 50 ng/L (850 pCi/L)

NOTES AWCA-AREA-WEIGHTED CONCENTRATION AVERAGE

1. AERIAL IMAGE MOSAICKED USING GOOGLE EARTH 2017 AERIAL PHOTOS.

2. SOME CONCENTRATIONS EXCEEDED THE US EPA ACTIVITY CONCENTRATION LIMIT OF 900 pCi/L (52.9 ng/L):1336a - 56.9 ng/LAND 1402 - 54.52 ng/L.

NO CONCENTRATIONS EXCEEDED THE NRC Tc-99 ACTIVITY CONCENTRATION LIMIT OF 3,790 pCi/L (222.9 ng/L).

3. PARTICLE TRACKING ARROWS DENOTE 60 DAY INTERVALS.

N 0

250 500

ATIACHMENT 4.0B AREA-WEIGHTED AVERAGING BOUNDARIES AND RESULTS SANDSTONE B, TRANSITION ZONE, ALLUVIUM Tc-99 GROUNDWATER ASSESSMENT MEMO CIMARRON SITE, OKLAHOMA

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~

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+ SANDSTONE B MONITOR WELL

+

TRANSITION ZONE MONITOR WELL 0

EXTRACTION WELL INJECTION WELL EXTRACTION TRENCH INJECTION TRENCH REVERSE PARTICLE TRACKING REVERSE PARTICLE TRACKING ARROWS US EPA Tc-99 CONCENTRATION LIMIT OF 52.9 ng/L (900 pCi/L)

,....., AWCA BOUNDARY FOR GE-WAA-03 & GE-L......11 WAA-06 TO GE-WAA-08

,....., AWCA BOUNDARY FOR GE-WAA-09 TO GE-L......11 WAA-11 10 ng/L (170 pCi/L) 20 ng/L (340 pCi/L}

30 ng/L (510 pCi/L) 40 ng/L (680 pCi/L) 50 ng/L (850 pCi/L}

60 ng/L (1020 pCi/L) 70 ng/L (1190 pCi/L) 80 ng/L (1360 pCi/L) 90 ng/L (1530 pCi/L)

NOTES AWCA-AREA-WEIGHTED CONCENTRATION AVERAGE

1. AERIAL IMAGE MOSAICKED USING GOOGLE EARTH 2017 AERIAL PHOTOS.

2. SOME CONCENTRATIONS EXCEEDED THE US EPA ACTIVITY CONCENTRATION LIMIT OF 900 pCi/L (52.9 ng/L):1346 - 95.6 ng/L.

NO CONCENTRATIONS EXCEEDED THE NRC Tc-99 ACTIVITY CONCENTRATION LIMIT OF 3,790 pCi/L (222.9 ng/L).

3. PARTICLE TRACKING ARROWS DENOTE 60 DAY INTERVALS.

0 250 500

.1 - Initial Influent Tc-99 Concentrations

.1 Initial and Future Maximum Influent Tc-99 Concentrations Cimarron Remediation Site Remediation Area 1 Well ID GE-WAA-01 WAA U>DCGL GE-WAA-02 GE-WAA-03 GE-WAA-04 GE-WAA-06 GE-WAA-07 GE-WAA-08 WAA-BLUFF GE-WAA-09 GE-WAA-10 GE-WAA-11 GE-WAA-12 GE-WAA-13

-WAA-EAST GE-WAA-14 GE-WAA-15 WAA-WEST GE-WAA-05 1206-NORTH GETR-WU-02 WU-1348 I

GETR-WU-01 WU-PBA GE-WU-01 Definitions:

AWCA - Area-Weighted Concentration Average C0 - initial concentration C1 - concentration at time "t" ng/L - nanogram per liter SSA - Sandstone A SSB - Sandstone B Trans. - transition Notes:

Extraction Well Tc-99 Influent Groundwater Co (ng/L)2 0

0 0

0 15 18 14 29 25 14 0

0 0

0 I

0 0

Extraction Well Tc-99 Influent Groundwater Ct

[AWCA-SSB/Alluvium/Trans. Zone]

(ng/L) 0 0

11.00 0

9.58 9.58 9.58 23.94 23.94 23.94 0

0 0

0 I

0 0

I 0

10nly Western Area Remediation Areas containing groundwater extraction components are listed.

2Concentrations estimated from hand drawn isopleths (10 ng/L contours) 3Estimated by flow rate-weighted averaging of initial Tc-99 groundwater concentrations for WAA U>DCGL extraction wells.

4Estimated by flow rate-weighted averaging of initial Tc-99 groundwater concentrations for WM-BLUFF extraction wells.

Influent Treatment Stream Tc-99 Influent Groundwater AWCA-SSA Co (ng/L)

(ng/L)3 NA 0.0 7.28 7.28 7.28 14.95 14.5 14.95 14.95 0

0 NA I

0.0 NA 0.0 I

NA 0.0 I

NA I

0.0 NA 0.0 Influent Treatment Stream Tc-99 Influent Groundwater Ct (ng/L)4 2.7 12.8 0.0 I

0.0 0.0 I

0.0 I

0.0 Assumed Ct Time "t" (days) 120 365 I

NA NA NA NA NA Rev.A 1/16/2020 Page 1 of 1

.4 - Tc-99 Retardation Parameters

.4 Tc-99 Retardation Parameters Cimarron Remediation Site Remediation Area WU-PBA (GE-WU-01)

WU-1348 (GETR-WU-01)

WAA U>DCGL (GE-WAA-01 through GE-WAA-04) 1206-NORTH (GETR-WU-02)

WAA-WEST (GE-WAA-05)

WAA-EAST (GE-WAA-14 and GE-WAA-15)

WAA-BLUFF (GE-WAA-06 through GE-WAA-13)

Definitions:

R - retardation Pb - bulk density n - porosity Kd - distribution coefficient g/ml - grams per milliliter ml/g - milliliters per gram Notes:

Bulk Density (g/ml) 1.81 1.81 1.81 1.81 1.81 1.81 1.81 Porosity1 Tc-99 Kd (ml/g)2 0.05 0.1 0.10 0.1 0.30 0.1 0.11 0.1 0.30 0.1 0.30 0.1 0.18 0.1 Rev.A 1/30/2020 b

R = l+ -

Kc.

R 4.62 2.81 1.60 2.65 1.60 1.60 2.03 1Assumes 30% transmissiv~ porosity for alluvial sand, as presented in the Technical Memorandum (TM002), September 10, 2018, page 3. Assumes 11 % transmissve porosity for BA 1 transition zone, as presented in Environmental Sequence Stratigraphy (ESS) and Porosity Analysis, Burial Area 1, dated April 6, 2018. Assumes 5% porosity for competent SSB bedrock.

Assume half influent area comes from SSB and half comes from alluvial sand for WM-BLUFF, resulting in an average transmissive porosity of 18%.

2Kd value sourced from Krupka et al. (2004) and PNNL-16531 (2007)

Page 1 of 1

.5 - Influent Concentration Decline Analysis

.5 Influent Concentration Decline Analysis Cimarron Remediation Site Influent Flow Adjusted Remediation Extraction Rate Flow Rate Area Well/Trench (gpm)

.(gpm) q q*%

1206-NORTH GETR-WU-02 8

WU-PBA GE-WU-01 5

WU-1348 GETR-WU-01 4

GE-WM-01 25 GE-WM-02 30 WM U>DCGL GE-WM-03 24 GE-WM-04 20 WM-WEST GE-WM-05 10 WM-BLUFF GE-WM-06 13 Nitrate Uranium Fluoride Technetium-99 (mg/L)

(ug/L)

(mg/L)

(ng/L)

Cmax Western Area 38.6 304 7

61.7 29.0 0.3 10.14 62.0 1.0 25.3 134 1

29.0 163 3

67.1 163 3

0.00 67.1 163 3

11.00 21.4

119 1

10.2 58.6 0.5 90.8 64.0 3.3 15 204 15.6 18.8 9.58 Weighted Nitrate Weighted Weighted (mg/L)

Uranium (ug/L) Fluoride (mg/L) q*cmax 309.1 2428.4 56.3 308.7 145.1 1.6 40.6 247.9 4.0 632.8 3354.5 35.0 869.4 4903.2 78.6 1610.9 3908.4 81.8 1610.9 3908.4 81.8 427.4 2380.6 28.8 102.4 586.4 4.5 1180.8 832.4 42.4 2652.0 202.8 244.4 Weighted Technetium-99 (ng/L) 0.0 264.0 195.0 124.5 Comments:

Governing Assumptions:

Rev.E 1/30/2020

- Maximum uranium, nitrate, and fluoride influent concentrations will not occur at time zero for extracUon wells GE-WAA-6 through -13; however maximum uranium, nitrate, and fluoride influent concentrations will occur at time zero for all other extraction wells and trenches.

- I ntitial (time zero) uranium, nitrate, and fluoride influent nitrate concentrations for GE-WAA-6 through -13 are based on representative SSBITZIA/fuvium concentrations.

- Future (time '(J uranium, nitrate, and fluoride inf/ uent nitrate concentrations for GE-WAA-6 through -13 are based on representative, upgradient (UP1 & UP2) SSA concentrations. 100% of this SSA groundwater contribution is assumed to be driven by the proposed injection features (i.e., natural groundwater flux from SSA is assumed to be negligible).

- Linear, incremental concentration averaging along trench alignment using isoconcentration contours [see Iner. AWCA Calcs_Rev. C (12 19)1.

- Interpolated concentrations calculated in Surfer [see Iner. AWCA Cales Rev. C (12-17-19)1.

- Linear, incremental concentration averaging along trench alignment using isoconcentration contours [see Iner. AWCA Calcs_Rev. C (12 19)1.

- Interpolated concentrations calculated in Surfer [see Iner. AWCA Cales Rev. C (12-17-19)1.

- Initial Influent Concentration: Interpolated concentrations calculated in Surfer [see Iner. AWCA Calcs_Rev. C (12-17-19)].

- Maximum Influent Concentration : [SSB/TZ/Alluvium] GE-WM-03 capture zone area-weighted incremental concentration averaging using isoconcentration contours [see Iner. AWCA Cales Rev. C (12-17-19)1.

- Interpolated concentrations calculated in Surfer [see Iner. AWCA Cales Rev. C (12-17-19)].

- Interpolated concentrations calculated in Surfer [see Iner. AWCA Cales Rev. C (12-17-19)1.

- Initial Influent Concentration: [SSB/TZ/Alluvium] interpolated concentrations calculated in Surfer for nitrate, fluoride, and uranium.

Interpolated concentrations calculated from hand drafted contours for Tc-99 fsee Iner. AWCA Cales Rev. C (12-17-19)1.

- Maximum Influent Concentration: [SSA] UP1 area-weighted incremental concentration averaging using isoconcentration contours for uranium, nitrate, and fluoride.

- Future Influent Concentration: [SSB/TZ/Alluvium] WM-BLUFF Capture Zone (GE-WM-06 through GE-WM-08) area-weighted incremental concentration averaging using isoconcentration contours for Tc-99 fsee Iner. AWCA Cales Rev. C (12-17-19)1.

Page 1 of 11

.5 Influent Concentration Decline Analysis Cimarron Remediation Site Influent Flow Adjusted Remediation Extraction Rate Flow Rate Area Well/Trench (gpm)

(gpm) q q*o/o GE-WM-07 13 GE-WM-08 13 WM-BLUFF GE-WM-09 13 GE-WM-10 13 Nitrate Uranium Fluoride Technetium-99 (mg/L)

(ug/L)

(mg/L)

(ng/L)

Cmax 73.2 10.9 2.6 18.0 204 15.6 18.8 9.58 141 7.70 3.54 14 204 15.6 18.8 9.58 218 4.77 2.46 29 378 26.3 7.8 23.94 207 6.40 2.03 25 378 26.3 7.8 23.94 Weighted Nitrate Weighted Weighted (mg/L)

Uranium (ug/L) Fluoride (mg/L) q*cmax 952.0 142.1 33.9 2652.0 202.8 244.4 1833.0 100.1 46.0 2652.0 202.8 244.4 2829.7 62.0 32.0 4914.0 341.9 101.4 2692.4 83.2 26.4 4914.0 341.9 101.4 Weighted Technetium-99 (ng/L) 234.0 124.5 182.0 124.5 377.0 311.2 325.0 311.2 Comments:

Rev. E 1/30/2020

- Initial Influent Concentration: [SSB/TZ/Alluvium] interpolated concentrations calculated in Surfer for nitrate, fluoride, and uranium.

Interpolated concentrations calculated from hand drafted contours for Tc-99 [see Iner. AWCA Cales Rev. C (12-17-19)1.

- Maximum Influent Concentration: [SSA] UP1 area-weighted incremental concentration averaging using isoconcentration contours for uranium, nitrate, and fluoride.

- Future Influent Concentration: [SSB/TZ/Alluvium] WM-BLUFF Capture Zone (GE-WM-06 through GE-WM-08) area-weighted incremental concentration averaging using isoconcentration contours for Tc-99 rsee Iner. AWCA Cales Rev. C (12-17-19)1.

- Initial Influent Concentration: [SSB/TZ/Alluvium] interpolated concentrations calculated in Surfer for nitrate, fluoride, and uranium.

Interpolated concentrations calculated from hand drafted contours for Tc-99 fsee Iner. AWCA Cales Rev. C (12-17-19)1.

- Maximum Influent Concentration: [SSA] UP1 area-weighted incremental concentration averaging using isoconcentration contours for uranium, nitrate, and fluoride.

- Future Influent Concentration: [SSB/TZ/Alluvium] WM-BLUFF Capture Zone (GE-WM-06 through GE-WM-08) area-weighted incremental concentration averaging using isoconcentration contours for Tc-99 rsee Iner. AWCA Cales Rev. C (12-17-19)1.

- Initial Influent Concentration: [SSB/TZ/Alluvium] interpolated concentrations calculated in Surfer for nitrate, fluoride, and uranium.

Interpolated concentrations calculated from hand drafted contours for Tc-99 fsee Iner. AWCA Cales Rev. C (12-17-19)1.

- Maximum Influent Concentration: [SSA] UP2 area-weighted incremental concentration averaging using isoconcentration contours for uranium, nitrate, and fluoride.

- Future Influent Concentration: [SSB/TZ/Alluvium] WM-BLUFF Capture Zone (GE-WM-09 through GE-WM-11) area-weighted incremental concentration averaging using isoconcentration contours for Tc-99 rsee Iner. AWCA Cales Rev. C (12-17-19)1.

- Initial Influent Concentration: [SSB/TZ/Alluvium] interpolated concentrations calculated in Surfer for nitrate, fluoride, and uranium.

Interpolated concentrations calculated from hand drafted contours for Tc-99 [see Iner. AWCA Cales Rev. C (12-17-19)1.

- Maximum Influent Concentration: [SSA] UP2 area-weighted incremental concentration averaging using isoconcentration contours for uranium, nitrate, and fluoride.

- Future Influent Concentration: [SSB/TZ/Alluvium] WM-BLUFF Capture Zone (GE-WM-09 through GE-WM-11) area-weighted incremental concentration averaging using isoconcentration contours for Tc-99 rsee Iner. AWCA Cales Rev. C <12-17-19)1.

Page 2 of 11

.5 Influent Concentration Decline Analysis Cimarron Remediation Site Influent Flow Adjusted Remediation Extraction Rate Flow Rate Area Well/Trench (gpm)

(gpm) q q*o/o GE-WM-11 14 WM-BLUFF GE-WM-12 13 GE-WM-13 12 GE-WM-14

. 10 WM-EAST GE-WM-15 10 Initial Lq*cmax 250 0

Initial Lq Initial Influent Concentration Nitrate Uranium Fluoride Technetium-99 (mg/L)

(ug/L)

(mg/L)

(ng/L)

Cmax 128 6.80 1.76 14 378 26.3 7.8 23.94 24.5 5.48 0.92 378 26.3 7.8 22.1 8.15 0.84 378 26.3 7.8 79.1 61.9 0.46 65.4 40.4 0.4 Weighted Nitrate Weighted Weighted (mg/L)

Uranium (ug/L) Fluoride (mg/L) q*Cmax 1794.9 95.2 24.6 5292.0 368.2 109.2 318.2 71.2 12.0 4914.0 341.9 101.4 265.3 97.8 10.1 4536.0 315.6 93.6 791.0 619.0 4.6 653.5 403.6 4.3 17612 20461 527 250 250 250 70.4 81.8 2.1 Weighted Technetium-99 (ng/L) 196.0 335.2 1509 250

6.0 Comments

Rev.E 1/30/2020

- Initial Influent Concentration: [SSB/TZ/Alluvium] interpolated concentrations calculated in Surfer for nitrate, fluoride, and uranium.

Interpolated concentrations calculated from hand drafted contours for Tc-99 [see Iner. AWCA Cales Rev. C (12-17-19)1.

- Maximum Influent Concentration: [SSA] UP2 area-weighted incremental concentration averaging using isoconcentration contours for uranium, nitrate, and fluoride. [SSB/TZ/Alluvium] WM-BLUFF Capture Zone (GE-WM-09 through GE-WM-11) area-weighted incremental concentration averaging using isoconcentration contours for Tc-99 [see Iner. AWCA Cales Rev. C (12-17-19)1.

- Initial Influent Concentration: [SSB/TZ/Alluvium] interpolated concentrations calculated in Surfer [see Iner. AWCA Calcs_Rev. C (12-17-19)].

- Maximum Influent Concentration: [SSA] UP2 area-weighted incremental concentration averaging using isoconcentration contours for uranium, nitrate, and fluoride. [see Iner. AWCA Calcs_Rev. C (12 19)1.

- Initial Influent Concentration: [SSB/TZ/Alluvium] interpolated concentrations calculated in Surfer [see Iner. AWCA Calcs_Rev. C (12-17-19)].

- Maximum Influent Concentration: [SSA] UP2 area-weighted incremental concentration averaging using isoconcentration contours for uranium, nitrate, and fluoride. [see Iner. AWCA Calcs_Rev. C (12 19)].

- Interpolated concentrations calculated in Surfer [see Iner. AWCA C~lcs Rev. C (12-17-19)].

- Interpolated concentrations calculated in Surfer [see Iner. AWCA Calcs_Rev. C (12-17-19)].

Page 3 of 11

.5 Influent Concentration Decline Analysis Cimarron Remediation Site Influent Flow Adjusted Remediation Extraction Rate Flow Rate Area Well/Trench BA1-A GETR-BA1-01 GETR-BA1-02 GE-BA1-02 BA1-B GE-BA1-03 GE-BA1-04 GE-BA1-05 GE-BA1-06 BA1-C GE-BA1-07 GE-BA1-08 GE-BA1-09 Lq*cmax Lq Max Influent Concentration Notes:

SSA - Sandstone A SSA - Sandstone B TZ - Transition Zone gpm - gallons per minute ug/L - micrograms per liter mg/L - milligrams per liter (gpm)

(gpm) q q*%

7 7

24 18 24 0

0 0

10 10 100 Nitrate Urnnium Fluoride (mg/L)

(ug/L)

(mg/L)

Cmax Burial Area 1 1,360 2,080 2,420 2,420 2,420 2,420 2,420 43.3 32.1 37.2 Weighted Technetium-99 Nitrate Weighted Weighted (ng/L)

(mg/L)

Uranium (ug/L) Fluoride (mg/L) q*cmax 9,520.00 14,560.00 58,080.00 43,560.00 58,080.00 0.00 0.00 0.00 321.00 372.00 184493.00 100 1845 Weighted Technetium-99 (ng/L)

Comments:

Governing Assumptions:.

Rev.E 1/30/2020

- Maximum uranium influent concentrations for all extraction wells and trenches will occur at time zero.

- Linear, incremental concentration averaging along trench alignment using isoconcentration contours see Iner. AWCA Calcs_Rev. C (12 19).

~ Interpolated concentrations calculated in Surfer [see Iner. AWCA Cales Rev. C (12-17-19)1.

- Interpolated concentrations calculated in Surfer [see Iner. AWCA Calcs_Rev. C (12-17-19)1.

- Interpolated concentrations calculated in Surfer [see Iner. AWCA Cales Rev. C (12-17-:19)1.

- Interpolated concentrations calculated in Surfer [see Iner. AWCA Calcs_Rev. C (12-17-19)1.

- Interpolated concentrations calculated in Surfer [see Iner. AWCA Cales Rev. C (12-17-19)1.

- Interpolated concentrations calculated in Surfer [see Iner. AWCA Cales Rev. C (12-17-19)].

- Interpolated concentrations calculated in Surfer [see Iner. AWCA Calcs_Rev. C (12-17-19)f Page 4 of 11

.5 Influent Concentration Decline Analysis Cimarron Remediation Site Remediation Area WU-PBA (GE-WU-01)

WU-1348 (GETR-WU-01)

WAA U>DCGL (GE-WAA-01 through GE-WAA-Oi 1206-NORTH (GETR-WU-02)

WAA-WEST (GE-WAA-05)

WAA-BLUFF (GE-WAA-06 through GE-WAA-13)

WAA-EAST (GE-WAA-14 & GE-WAA-15)

Ci (ng/L) 0.0 14.51 Ci Cmax 6

Source (ng/L)

FWCA 2.7 FWCA 12.80 WATF - Technetium-99 Is Ci representative Cmax 6

of Cmax?

Flow Rate Source (Y/N)

(gpm)

R1 y

5 4.6 y

4 2.8 AWCA/FWCA N

99 1.60 y

8 2.7 y

10 1.60 AWCA/FWCA N

104 2.03 y

20 1.60 Combined Treatment System Influent Flow Rate:i 250 Notes:

C -( (-Q/(PV*R))t t-oe Ci - initial concentration Ct - final concentration Cmax - maximum concentration gpm - gallons per minute MCL - maximum contaminant level mg/L - milligrams per liter R - retardation PV - pore volume Q - flow rate 0

R = l + -

Ka n

AWCA - Area-weighted concentration averaging FWCA - Flow rate-weighted concentration averaging LWCA - Linear-weighted concentration averaging SIC - Surfer-interpolated concentration Pv1,2,3 (ft3) 231,264 61,800 4,177,559 3,014 2,387,058 6,811,932 4,716,357 1Retardation (R) and pore volume (PV) taken from remediation duration estimate calculations [DRAFT _Remediation Duration Estimates_Rev. B (09-10-18)].

PV Q

(liters)

( I iters/day) 6,548,662 27,255 1,749,984 21,804 118,295,089 539,648 85,334 43,608 67,593,844 54,510

~~

192,892,116 566,9,03 133,552,129 109,020 Time Required for Initial Cone. to Reach Max. Level (days)2 0

0 120 0

0 365 0

cubic foot=

gpm =

cf (ng/L) 0.00 0.03 Rev.E 1/30/2020 Combined Influent cf (ng/L) 0.013 28.3168 liters 5451 liters per day 2Based on forward particle tracking results for WU-UP1 and WU-UP2 injection components, and uranium and nitrate plume distribution depicted on isopleth maps, maxium uranium and nitrate groundwater concentrations will report to WAA "BLUFF" extraction wells approximately 1 year following intiation of water injection at UP1 and UP2.

3The WM "BLUFF" pore volume is inconsequential for remediation duration since the remediation timeframe for this area is predicated on UP1/UP2 remediation timeframe.

4Since intial nitrate groundwater concentrations for WU "1206 SOUTH" and WM "U<DCGL" WEST are below the applicable remediation criteria, the highest representative nitrate concentration for any well in each area was used in the influent concentration decay analysis.

5The combined influent flow rate presented in the table reflects initial operating conditions. The influent flow rate is expected to decline over the course of the remediation campaign. Combined influent flow rates for each month of remediation are provided in the concentration decay analysis tables.

6The Cmax value for the WM-BLUFF remediation area incorporates the anticipated concentration increase at GE-WM-11. Cmax occurs at GE-WM-11 approximately 365 days from startup, but the flow rate weighted average for WM-BLUFF is less than Ci at time 0. However, the flow rate weighted average Cmax at 365 days is greater than the concentration at 365 days, based on the concentration decay function. Therefore, Cmax represents an increase in the concentration decay curve at time = 365 days.

Page 5 of 11

.5 Influent Concentration Decline Analysis Cimarron Remediation Site Western Area Combined Influent - Technetium-99 WU-PBA (GE-WU-01)

Area Ci (ng/L) 1 Cmax (ng/L)

Flow Rate (gpm) 5 R

4.6 PV (liters) 6,548,662 Q (liters/day) 27,255 Time Required for Initial Cone. to Increase to Future Level (months) 0 Cumulative Time WU-PBA (Months) 0 1

2 3

4 5

6 7

8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 WAA U>DCGL (GE-WAA-WEST (GE-WAA-WU-1348 (GETR-WU-WAA-EAST (GE-WAA-WAA-01 through GE-WAA-04)

05)

01) 14 & GE-WAA-15) 0.00 2.67 99 10 4

20 1.6 1.6 2.8 1.6 118,295,089 67,593,844 1,749,984 133,552,129 539,648 54,510 21,804 109,020 120 0

0 0

WAA U>DCGL WAA-WEST WU-1348 WAA-EAST 0.00 --

0.00 --

2.67 --

2.45 --

2.24 --

2.06 --

1.88 --

1. 73 --

1.58 --

1.45 --

1.33 --

1.22 --

1.12 --

1.03 --

0.94 --

0.86 --

0.79 --

0.73 --

0.67 --

0.61 --

0.56 --

0.51 --

0.47 --

0.43 --

0.40 --

0.36 --

0.33 --

0.30 --

0.28 --

WAA-BLUFF (GE-WAA-1206-NORTH (GETR-06 through GE-WAA-

13)

WU-02) 14.51 12.80 104 8

2.03 2.7 192,892,116 85,334 566,903 43,608 365 0

WAA-BLUFF 1206-NORTH 14.51 --

13.89 --

13.29 --

12.72 --

12.17 --

11.65 --

11.15 --

10.67 --

10.21 --

9.77 --

9.35 --

8.95 --

8.56 --

12.80 --

12.25 --

11.72 --

11.22 --

10.74 --

10.28 --

9.83 --

9.41 --

9.01 --

8.62 --

8.25 --

7.89 --

7.55 --

7.23 --

6.92 --

6.62 --

6.34 --

6.06 --

5.80 --

Rev.E 1/30/2020 C -( (-Q/(PV*R)}t t-oe WEIGHTED WEIGHTED Combined AVERAGE AVERAGE2 Influent Flow (ng/L)

(oCi/U Rate (gpm) 6.04 102.61 250 5.78 98.20 250 5.53 93.98 250 5.29 89.94 250 5.06 86.07 250 5.90 100.32 250 5.61 95.29 250 5.33 90.53 250 5.06 86.03 250 4.81 81.78 250 4.57 77.76 250 4.35 73.95 250 4.14 70.34 250 5.85 99.49 250 5.58 94.86 250 5.32 90.45 250 5.07 86.26 250 4.84 82.27 250 4.62 78.48 250 4.40 74.87 250 4.20 71.44 250 4.01 68.17 250 3.83 65.06 250 3.65 62.10 250 3.49 59.28 250 3.33 56.59 250 3.18 54.03 250 3.03 51.59 250 2.90 49.27 250 2.77 47.05 250 2.64 44.94 250 2.52 42.92 250 Page 6 of 11

.5 Influent Concentration Decline Analysis Cimarron Remediation Site Western Area Combined Influent - Technetium-99 Area C1 (ng/L}

Cmax 1 (ng/L)

Flow Rate (gpm)

R PV (liters)

Q (liters/day)

Time Required for Initial Cone. to Increase to Future Level (months)

Cumulative Time (Months) 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 WU-PBA (GE-WU-01) 5 4.6 6,548,662 27,255 0

WU-PBA WAA U>DCGL (GE-WAA-WEST (GE-WAA-WAA-01 through GE-WAA-04) 0.00 2.67 99 1.6 118,295,089 539,648 WAA U>DCGL 120 0.26 --

0.24 --

0.22 --

0.20 --

0.18 --

0.17 --

0.15 --

0.14 --

0.13 --

0.12 --

0.11 --

0.10 --

0.09 --

0.08 --

0.07 --

0.06 --

0.05 --

0.04 --

0.03 --

0.02 --

05) 10 1.6 67,593,844 54,510 0

WAA-WEST WU-1348 (GETR-WU-WAA-EAST (GE-WAA-

01) 14 & GE-WAA-15) 4 20 2.8 1.6 1,749,984 133,552, 129 21,804 109,020 0

0 WU-1348 WAA-EAST WAA-BLUFF (GE-WAA-1206-NORTH (GETR-06 through GE-WAA-

13)

WU-02) 14.51 12.80 104 8

2.03 2.7 192,892,116 85,334 566,903 43,608 365 0

WAA-BLUFF 1206-NORTH 5.55 --

5.31 --

5.09 --

4.87 --

4.66 --

4.46 --

4.27 --

4.08 --

3.91 --

3.74 --

3.58 --

3.42 --

3.28 --

3.14 --

3.00 --

2.87 --

2.75 --

2.63 --

2.52 --

2.41 --

2.31 --

2.21 --

2.11 --

2.02 --

1.93 --

1.85 --

1.77 --

1.70 --

1.62 --

1.55 --

1.49 --

1.42 --

Rev.E 1/30/2020 C -( (-Q/(PV*R})t t-oe WEIGHTED WEIGHTED Combined AVERAGE AVERAGE2 Influent Flow (ng/L)

(pCi/L)

Rate (t:mm) 2.41 41.00 250 2.30 39.17 250 2.20 37.42 250 2.10 35.75 250 2.01 34.16 250 1.92 32.65 250 1.84 31.20 250 1.75 29.81 250 1.68 28.50 250 1.60 27.24 250 1.53 26.03 250 1.46 24.88 250 1.40 23.79 250 1.34 22.74 250 1.28 21.74 250 1.22 20.79 250 1.17 19.87 250 1.12 19.00 250 1.07 18.17 250 1.02 17.37 250 0.98 16.61 250 0.93 15.89 250 0.89 15.19 250 0.85 14.53 250 0.82 13.89 250 0.78 13.29 250 0.75 12.71 250 0.71 12.15 250 0.68 11.63 250 0.65 11.12 250 0.63 10.64 250 0.60 10.17 250 Page 7 of 11

.5 Influent Concentration Decline Analysis Cimarron Remediation Site Western Area Combined Influent - Technetium-99 Area Ci (ng/L)

Cmax 1 (ng/L)

Flow Rate (gpm)

R PV (liters)

Q (liters/day)

Time Required for Initial Cone. to Increase to Future Level (months)

Cumulative Time (Months) 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 WU-PBA (GE-WU-01) 5 4.6 6,548,662 27,255 0

WU-PBA WAA U>DCGL (GE-WAA-WEST (GE-WAA-WAA-01 through GE-WAA-04) 0.00 2.67 99 1.6 118,295,089 539,648 WAA U>DCGL 120 0.02 --

0.01 --

0.00 --

05) 10 1.6 67,593,844 54,510 0

WAA-WEST WU-1348 (GETR-WU-

01) 4 2.8 1,749,984 21,804 0

WU-1348 WAA-EAST (GE-WAA-14 & GE-WAA-15) 20 1.6 133,552,129 109,020 0

WAA-EAST WAA-BLUFF (GE-WAA-06 through GE-WAA-

13) 14.51 12.80 104 2.03 192,892,116 566,903 WAA-BLUFF 365 1.36 --

1.30 --

1.25 --

1.19 --

1.14 --

1.09 --

1.05 --

1.00 --

0.96 --

0.92 --

0.88 --

0.84 --

0.80 --

0.77 --

0.74 --

0.70 --

0.67 --

0.64 --

0.62 --

0.59 --

0.57 --

0.54 --

0.52 --

0.50 --

0.47 --

0.45 --

0.43 --

0.42 --

0.40 --

0.38 --

0.36 --

0.35 --

1206-NORTH (GETR-WU-02) 8 2.7 85,334 43,608 0

1206-NORTH Rev.E 1/30/2020 C -( (-Q/(PV*R))t t-oe WEIGHTED AVERAGE (ng/L) 0.57 0.55 0.52 0.50 0.48 0.46 0.44 0.42 0.40 0.38 0.37 0.35 0.34 0.32 0.31 0.29 0.28 0.27 0.26 o.2s

0.24 0.23 0.22 0.21 0.20 0.19 0.18 0.17 0.17 0.16 0.15 0.15 WEIGHTED AVERAGE2 (oCi/U 9.73 9.31 8.90 8.52 8.15 7.80 7.46 7.13 6.82 6.53 6.25 5.98 5.72 5.47 5.23 5.01 4.79 4.58 4.39 4.20 4.01 3.84 3.68 3.52 3.37 3.22 3.08 2.95 2.82 2.70 2.58 2.47 Combined Influent Flow Rate (aom) 250 250 250 250 250 250 250 250 250 250 250 250 250 250 250 250 250 250 250 250 242 242 242 242 242 242 242 242 242 242 242 242 Page 8 of 11

.5 Influent Concentration Decline Analysis Cimarron Remediation Site Western Area Combined Influent - Technetium-99 Area Ci (ng/L)

Cmax 1 (ng/L)

Flow Rate (gpm)

R PV (liters)

Q (liters/day)

Time Required for Initial Cone. to Increase to Future Level (months)

Cumulative Time (Months) 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 WU-PBA (GE-WU-01) 5 4.6 6,548,662 27,255 0

WU-PBA WAA U>DCGL (GE-WAA-WEST (GE-WAA-WAA-01 through GE-WAA-04) 0.00 2.67 99 1.6 118,295,089 539,648 WAA U>DCGL 120 0.00 --

0.00 --

05) 10 1.6 67,593,844 54,510 0

WAA-WEST WU-1348 (GETR-WU-WM-EAST (GE-WAA-

01) 14 & GE-WAA-15) 4 20 2.8 1.6 1,749,984 133,552,129 21,804 109,020 0

0 WU-1348 WAA-EAST WAA-BLUFF (GE-WAA-1206-NORTH (GETR-06 through GE-WAA-WU-02)

13) 14.51 12.80 104 8

2.03 2.7 192,892,116 85,334 566,903 43,608 365 0

WAA-BLUFF 1206-NORTH 0.33 --

0.32 --

0.31 --

0.29 --

0.28 --

0.27 --

0.26 --

0.25 --

0.23 --

0.22 --

0.21 --

0.20 --

0.19 --

0.18 --

0.17 --

0.16 --

0.15 --

0.14 --

0.13 --

0.12 --

0.11 --

0.10 --

0.09 --

Rev.E 1/30/2020 C - *(

(-Q/(PV*R))t

. t-oe WEIGHTED WEIGHTED Combined AVERAGE AVERAGE2 Influent Flow (ng/L)

{oCi/L)

Rate (cmm) 0.14 2.36 242 0.13 2.26 242 0.13 2.17 242 0.12 2.07 242 0.12 1.98 242 0.11 1.90 242 0.11 1.82 242 0.10 1.74 242 0.10 1.66 242 0.09 1.59 242 0.09 1.52 242 0.09 1.46 242 0.08 1.39 242 0.08 1.33 242 0.08 1.28 242 0.07 1.22 242 0.07 1.17 242 0.07 1.12 242 0.06 1.07 242 0.06 1.02 242 0.06 0.98 242 0.06 0.94 242 0.05 0.90 242 0.05 0.86 242 0.05 0.82 242 0.05 0.79 242 0.04 0.75 242 0.04 0.72 242 0.04 0.69 242 0.04 0.66 242 0.04 0.63 242 0.04 0.60 242 Page 9 of 11

.5 Influent Concentration Decline Analysis Cimarron Remediation Site Western Area Combined Influent - Technetium-99 Area Ci (ng/L)

Cmax 1 (ng/L)

Flow Rate (gpm)

R PV (liters)

Q (liters/day)

Time Required for Initial Cone. to Increase to Future Level (months)

Cumulative Time Notes:

(Months) 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 WU-PBA (GE-WU-01) 5 4.6 6,548,662 27,255 0

WU-PBA WAA U>DCGL (GE-WAA-WEST (GE-WAA-WAA-01 through GE-WAA-04) 0.00 2.67 99 1.6 118,295,089 539,648 WAA U>DCGL 120 0.00 --

0.00 --

05) 10 1.6 67,593,844 54,510 0

WAA-WEST WU-1348 (GETR-WU-WAA-EAST (GE-WAA-

01) 14 & GE-WAA-15) 4 20 2.8 1.6 1,749,984 133,552,129 21,804 109,020 0

0 WU-1348 WAA-EAST WAA-BLUFF (GE-WAA-06 through GE-WAA-

13) 14.51 12.80 104 2.03 192,892,116 566,903 WAA-BLUFF 365 0.08 --

0.08 --

0.07 --

0.06 --

0.05 --

0.04 --

0.03 --

1206-NORTH (GETR-WU-02) 8 2.7 85,334 43,608 0

1206-NORTH Rev.E 1/30/2020 C -( (-Q/(PV*R)}t t-oe WEIGHTED AVERAGE (ng/L) 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.01 0.01 0.01 WEIGHTED AVERAGE 2

(oCi/U 0.58 0.55 0.53 0.51 0.48 0.46 0.44 0.43 0.41 0.39 0.37 0.36 0.34 0.33 0.31 0.30 0.29 0.27 0.26 0.25 0.24 0.23 0.22 Combined Influent Flow Rate {aom) 238 238 238 238 238 238 238 238 238 238 238 238 238 238 238 238 238 238 238 238 238 238 238 1The Cmax value for the WM-BLUFF remediation area incorporates the anticipated concentration increase at GE-WM-11. Cmax occurs at GE-WAA-11 approximately 365 days from startup, but the flow rate weighted average for WM-BLUFF is less than Ci at time 0.

However, the flow rate weighted average Cmax at 365 days is greater than the concentration at 365 days, based on the concentration decay function. Therefore, Cmax represents an increase in the concentration decay curve at time= 365 days.

2The Tc-99 activity to mass conversion factor is 1. 7E-02 Ci/g (49 CFR 173.435 Table of A 1 and A2 values).

Page 10 of 11

.5 Influent Concentration Decline Analysis Cimarron Remediation Site 16.0 14.0 12.0

~ 10.0 0.0 C

C 0

'..j:i

~ c 8.o Q) u C

0 u CJ)

~

u 6.0 I-4.0 2.0 0.0

\\ ' \\

' \\

' J ~

~

\\

\\ ' \\

\\

~ \\

~~

~

i' ~

~

r--.........

I\\

\\

~

Western Area Tc-99 Concentration Trends Combined Influent I\\,

' ~

~

r---..

~

i-,.... i--....... ~

I I I I Months from Treatment Start I

I I I I I WEIGHTED AVERAGE (ng/L}

WU-PBA WU-1348 WAAU>DCGL 1206-NORTH WAA-WEST WAA-BLUFF WAA-EAST Page 11 of 11

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