ML22110A091
| ML22110A091 | |
| Person / Time | |
|---|---|
| Site: | 07000925 |
| Issue date: | 04/20/2022 |
| From: | Cimarron Environmental Response Trust |
| To: | Document Control Desk, Office of Nuclear Material Safety and Safeguards |
| References | |
| Download: ML22110A091 (12) | |
Text
Revised Conceptual Site Model Source: Figure 2A, Environmental Sequence Stratigraphy (ESS) and Porosity Analysis, Burial Area 1, ML18100A297.
Cross section lines from 2006 Revised Conceptual Site Model. Section Line A-A is along the approximate centerline of the uranium plume.
Revised Conceptual Site Model Source: Figure 4, Environmental Sequence Stratigraphy (ESS) and Porosity Analysis, Burial Area 1, ML18100A297.
- Black line - escarpment at groundwater surface
- Magenta - SSB surface
- Tan - interconnected, permeable sand channel deposits
Revised Conceptual Site Model This image was not taken from a report. It was generated from the same EVS model to provide a different view.
Revised Conceptual Site Model Source: Figures 5, 6, and 7, Environmental Sequence Stratigraphy (ESS) and Porosity Analysis, Burial Area 1, ML18100A297.
- Tan - interconnected, permeable sand channel deposits
- Green - Upper Gully Fill deposits
- Blue - Lower Gully Fill deposits
Remediation Design This figure was generated for internal use only and was not incorporated into a report.
- Gray - extent of interconnected, permeable sand channel deposits
- Red dashed lines -
groundwater extraction trenches
BA1 Transition Zone Remediation Plan
- Light green - groundwater extraction trenches
- Light blue - treated water injection trenches Source: Figure 8-2(b), Facility Decommissioning Plan - Rev 2, ML21076A479
Distribution of Uranium in BA1
- Uranium is not evenly distributed within BA1 aquifer sediments
- Based on results for 204 soil samples collected from 21 borings completed in the BA1 Transition Zone, uranium in BA1 primarily resides within permeable sand channel deposits
- 45 samples collected from 10 borings exhibited U > 7 pCi/g (background)
- Of those 45, only 8 were collected from low permeability material
Distribution of Uranium in BA1 Note: two of the three samples in the two highest concentration categories were collected from mixed sand/clay zones and the third sample was collected at the base of a sand zone in "shale".
- Maximum background =
7 pCi/g uranium
- 159 samples
< 7 pCi/g uranium This chart was generated for internal use only and was not incorporated into a report.
Distribution of Uranium in BA1
- The BA1 permeable sand channel deposits represent approx. 16% of the total transmissive pore volume; however, 100% of the saturated pore volume was used to estimated the remediation time requirement.
Source: Environmental Sequence Stratigraphy (ESS) and Porosity Analysis, Burial Area 1, ML18100A297.
Note: Sand channel deposits represent 9% of the bulk aquifer volume and 16% of the transmissive pore volume.
BA1 Remediation Duration Projection
- The linear sorption model* used to estimate timeframe
- Key inputs:
- Retardation parameters (density, porosity, Kd)
- Saturated pore volume (3D TZ/SSB body bounded by MCL, capture zone, TZ/Alluvium interface)
- Co - highest U conc. in any well
- Cf - DCGL
- Projected extraction rate (derived from GETR-BA1-01 pump test)
- Other than determining the injection/extraction capture zone, the numerical groundwater model was not used in estimating remediation timeframe.
Remediation and Water Treatment Duration Estimate Calculations BA1-A ("U>DCGL" Transition Zone / Sandstone B)
Table 1: Retardation Calculation Bulk Density (g/ml)
Porosity [n]1 Uranium Kd (ml/g)2 Retardation [R]
1.81 0.11 3
50.36 Table 2: Remediation Pore Volume Calculation Bulk Saturated Plume Volume [V]3 (ft3)
Porosity [n]1 Pore Volume (ft3)
[PV = V*n]
Pore Volume [PV]
(gallons) 818,370 0.11 90,021 673,355 Table 3: Estimated Initial Aqueous-Phase Contaminant Concentration Initial Aqueous-Phase Contaminant Concentration
(µg/L) 823.62 2,975 Table 4: Estimated Number of Pore Volumes to Achieve Remediation Goal (180 pCi/L)
R Uranium Cleanup Concentration
(µg/L)4 Initial Aqueous-Phase Contaminant Concentration
(µg/L)5 No. of Pore Volumes6
[#PV = -R ln(Cleanup/Initial)]
50.36 201 2,975 135.7 Table 5: Estimated Time to Achieve Remediation Goal (180 pCi/L)
No. of Pore Volumes Pore Volume (gallons)
Flow Rate (gpm)7 Flow Rate (gpd)
Duration Estimate (days)
Duration Estimate (months)
Remarks 135.7 673,355 14 20,160 4,533 149.1 Time to achieve cleanup goal (DCGL) and discontinue remediation.
Concentration Basis Maximum Representative Concentration within Remediation Area Remarks Incremental Averaging of Concentrations within Remediation Area Remarks Pore volumes required to achieve cleanup goal (DCGL) and discontinue remediation Representative uranium concentration for TMW-09 Average uranium concentration in Area A Source: Attachment 9.1, Basis of Design for Groundwater Remediation, Appendix K to Facility Decommissioning Plan - Rev 2, ML21076A479.
BA1 Remediation Duration Projection
- Assumptions & Limitations
- The estimated number of pore volume (PV) exchanges required to achieve 180 pCi/L assumes linear, reversible and instantaneous desorption.
- Treated water will be injected during full-scale remediation; injection-enhanced conditions are not reflected in the extraction rate used in timeframe calculations.