DRC-2013-001269 - 0901a0688034d6f8

State of Utah
GARY R HERBERT
Governor
GREG BELL
Lieulenanl Governor
February 13,2013
Department of
Environmental Quality
Amanda Smith
Executive Direclor
DIVISION OF RADIATION CONTROL
Rusty Lundberg
Direclor
DRC-2013-001269
Harold Roberts
Executive Vice President and Chief Operating Officer
Energy Fuels Resources (USA) Inc.
225 Union Blvd., Suite 600
Lakewood, CO 80228
RE: Review of August 15, 2012 (and May 31, 2012) Energy Fuels Resources (USA) Inc.
Responses to Round 1 Interrogatories on Revision 5 Reclamation Plan Review, White Mesa
Mill Site, Blanding, Utah, report dated September 2011
Dear Mr. Roberts:
Enclosed is URS Professional Solutions' review of Energy Fuels Resources responses to the
Round I Interrogatories on Revision 5 Reclamation Plan. The enclosed table (Table 1) and
attached Technical Memorai^um (Attachment A - Revision 5 Reclamation Plan Round 1 [Rd
1] Interrogatories, Responses, and Discussion) document the results of URS Professional
Solutions' (Professional Solutions') reviev\(, conducted on behalf ofthe Utah Division of
Radiation Control (the Division), of Energy Fuels Resources (USA) Inc.'s (EFR's) Responses
to Round 1 (Rd 1) Interrogatories submitted by the on Revision 5 Reclamation Plan dated
September 2011 prepared by Denison Mines (USA) Corp. (now EFR).
Table 1 presented below states additional analyses and information required, in Professional
Solutions' opinion, to enable the Division to thoroughly evaluate EFR's Revision 5
Reclamation Plan report and responses to the Round 1 Interrogatories previously submitted on
that report. Additional information requested from EFR is summarized in the third column of
the table. The table summarizes remaining technical issues related to the Revision 5
Reclamation Plan (and associated appendices and other supporting documents), identifies
additional actions, analyses, and/or revisions that are requested from EFR in conjunction with
the review of the Revision 5 Reclamation Plan in order to allow these identified issues to be
adequately evaluated and resolved.
Attachment A restates the Rd 1 interrogatories the Division transmitted to EFR on the
Revision 5 Reclamation Plan, repeats EFR's responses to those interrogatories, and provides
discussion summarizing the results of the review of each response. The Rd 1 Interrogatories
and EFR's Responses to those interrogatories are summarized in the same order in which the
195 North 1950 West • Salt Lake City, UT
Maiimg Address P O Box 144850 • Salt Lake City, UT 84114-4850
Telephone [phone] • Fax [phone] -TDD [phone]
www deq utah gov
Pnnted on 100% recycled paper
Page 2
Rd 1 Interrogatories were originally submitted.
If you have any questions regarding this letter or the enclosure, please feel free to contact me
at 801-536-4263.
Sincerely,
rohn Hultquist, Smion Manager
LLRW/Uranium Mill Licensing Section
JH:jh
Cc: Jo Arm Tischler, Director, Compliance and Permitting
WllJO Technical
Memorandum
Date: Februarys, 2013 UTl 1.1102.004 OUT
To: John Hultquist, Utah Division of Radiation Control
From:
Jon Luellen, URS Professional Solutions
Robert Baird, URS Professional Solutions
Subject:..
Review of August 15, 2012 (and May 31,2012) Energy Fuels Resources (USA) Inc.
Responses to Round 1 Interrogatories on Revision 5 Reclamation Plan Review, White
Mesa Mill Site, Blanding, Utah, report dated September 2011
The enclosed table (Table 1) and attached Technical Memorandum (Attachment A - Revision 5
Reclamation Plan Round 1 [Rd 1] Interrogatories, Responses, and Discussion) document the results of
URS Professional Solutions' (Professional Solutions') review, conducted on behalf of the Utah Division
of Radiation Control (the Division), of Energy Fuels Resources (USA) Inc.'s (EFR's) Responses to
Round 1 (Rd 1) Interrogatories submitted by the on Revision 5 Reclamation Plan dated September 2011
prepared by Denison Mines (USA) Corp. (now EFR).
Table 1 presented below is intended to succinctly state additional analyses and information required, in
Professional Solutions' opinion, to enable the Division to thoroughly evaluate EFR's Revision 5
Reclamation Plan report and responses to the Round 1 Interrogatories previously submitted on that
report. Salient additional information requested from EFR is summarized in the third column ofthe
table. The table summarizes remaining technical issues related to the Revision 5 Reclamation Plan (and
associated appendices and other supporting documents), identifies additional actions, analyses, and/or
revisions that are requested from EFR in conjunction with the review of the Revision 5 Reclamation
Plan in order to allow these identified issues to be adequately evaluated and resolved.
Attachment A restates the Rd 1 interrogatories the Division transmitted to EFR on the Revision 5
Reclamation Plan, repeats EFR's responses to those interrogatories, and provides discussion
summarizing the results of the review of each response. The Rd 1 Interrogatories and EFR's Responses
to those interrogatories are summarized in the same order in which the Rd 1 Interrogatories were
originally submitted.
URS Corporation
756 E Winchester Street, Suite 400
Salt Lake City. UT 84107
Tel. [phone]
Fax [phone]
www urscorp com
TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
Table of Contents
1.0 Responses to Reclamation Plan Rev. 4.0 Interrogatories 25
1.1 Round 1 Interrogatory White Mesa Rec Plan Rev. 5.0, R313-24-4; 10CFR40.31(H); INT 01/1; Responses
to Reclamation Plan Rev. 4.0 Interrogatories 25
1.2 EFR Responses to Rd 1 Interrogatoiy White Mesa Rec Plan Rev. 5.0; R313-24-4; 10CFR40.31 (H); INT
01/1; Responses to Reclamation Plan Rev. 4.0 Interrogatories 25
1.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa Rec Plan 5.0; R313-24-4; 10
CFR40.31(H); INT 01/1; Responses to Reclamation Plaii Rev. 4.0 Interrogatories 26
2.0 Engineering Drawings 26
2.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4; 10CFR40 Appendix A, Criterion 4; INT
02/1; Engineering Drawings 26
2.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4; 10CFR40 Appendix A,
Criterion 4; INT 02/1; Engineering Drawings 27
2.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4;
10CFR40 Appendix A, Criterion 4; INT 02/1; Engineering Drawings ..28
3.0 CQA/CQC Plan, Cover Constructability, and Filter and Rock Riprap Layer Criteria and Placement 29
3.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4; 10 CFR 40 Appendix A, Criterion I and
4; INT 03/1; CQA/CQC Plan, Cover Constructability, and Filter and Rock Riprap Layer Criteria and
Placement 29
3.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4; 10CFR40 Appendix A,
Criterion 4; INT 03/1; CQA/CQC Plan, Cover Constructability, and Filter and Rock Riprap Layer Criteria
and Placement 30
3.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa Revised RecPlan 5.0; R313-
24-4; 10CFR40 Appendix A, Criterion 4; INT 03/1; CQA/CQC Plan, Cover Constructability, and Filter and
Rock Riprap Layer Criteria and Placement 32
4.0 Void Space Criteria for Debris, Rubble Placement, and Soil/Backfill Requirements 34
4.1 Round I Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4; 10CFR40, APPENDIX A, Criterion 4;
INT 04/1; Void Space Criteria for Debris, Rubble Placement, and Soil/Backfill Requirements 34
4.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4; 10CFR40, APPENDIX A,
Criterion 4; INT 04/1; Void Space Criteria for Debris, Rubble Placement, and Soil/Backfill Requiremeiits
36
4.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4;
10CFR40, APPENDIX A, Criterion 4; INT 04/1; Void Space Criteria for Debris, Rubble Placement, and
Soil/Backfill Requirements 40
5.0 Seismic Hazard Evaluation 42
5.1 Round 1 Interrogatory White Mesa RecPlan 5.0 R313-24-4; 10CFR40, Appendix A; INT 05/1; Seismic
Hazard Evaluation 42
5.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan 5.0 R313-24-4; 10CFR40, Appendix A; INT
05/1; Seismic Hazard Evaluation 43
5.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan 5.0 R313-24-4;
10CFR40, Appendix A; INT 05/1; Seismic Hazard Evaluation 45\,
6.0 Slope Stability 47
6.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4; 10CFR40, Appendix A, Criterion 1; INT
06/1; Slope Stability 47
TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
6.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4; 10CFR40, Appendix A,
Criterion 1; INT 06/1; Slope Stability 48
6.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4;
10CFR40, Appendix A, Criterion 1; INT 06/1; Slope Stability 48
7.0 Settlement and Potential for Cover Slope Reversal and/or Cover Layer Cracking 50
7.1 Round 1 Interrogatory White Mesa RecPlan 5.0 R313-24-4; 10CFR40, Appendix A, Criterion 4; INT 07/1;
Technical Analysis - Settlement and Potential for Cover Slope Reversal and/or Cover Layer Cracking 50
7.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan 5.0 R313-24-4; I0CFR40, Appendix A,
Criterion 4; INT 07/1; Technical Analysis - Settlement and Potential for Cover Slope Reversal and/or
Cover Layer Cracking 52
7.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev. 5.0; R313-24-4;
I0CFR40, Appendix A, Criterion 4; INT 07/1; Technical Analysis - Settlement and Potential for Cover
Slope Reversal and/or Cover Layer Cracking 53
8.0 Erosion Stability Evaluation 58
8.1 Round I Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; I0CFR40, Appendix A, Criterion 4; INT
08/1; Technical Analysis - Erosion Stability Evaluation 58
8.2 EFR Responses to Rd I Interrogatory White Mesa RecPlan 5.0 R313-24-4; 10CFR40, Appendix A,
Criterion 4; INT 08/1; Technical Analysis - Erosion Stability Analysis 60
8.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev. 5.0; R313-24-4;
I0CFR40, Appendix A, Criterion 4; fNT 08/1: Technical Analysis - Erosion Stability Analysis 61
9.0 Liquefaction...., 62
9.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; 10CFR40, Appendix A, Criterion 1; INT
09/1; Liquefaction 62
9.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan 5.0 R313-24-4; I0CFR40, Appendix A,
Criterion 1; INT 09/1; Liquefaction 62
9.3 Division's Assessment of EFR Responses to Rd I Interrogatory White Mesa RecPlan Rev. 5.0; R3I3-24-4;
10CFR40, Appendix A, Criterion I; INT 09/1; Liquefaction 65
10.0 Frost Penetration Analysis 69
10.1 Round 1 Interrogatory White Mesa'RecPlan REV 5.0 R313-24-4; 10CFR40, APPENDIX A, CRITERION
6; INT 08/1; Technical Analyses - Frost Penetration Analysis 69
10.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan 5.0 R313-24-4; 10CFR40, Appendix A,
Criterion 6; INT lO/I; Technical Analyses - Frost Penetration Analysis 70
10.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev, 5.0; R313-24-4;
10CFR40, Appendix A, Criterion 6; INT 10/1; Technical Analyses - Frost Penetration Analysis 70
11.0 Vegetation and Biointrusion Evaluation and Revegetation Plan 71
11.1 Round 1 Interrogatory White Mesa RecPlan REV 5,0 R313-24-4; I0CFR40, Appendix A, INT 11/1;
Vegetation and Biointrusion Evaluation and Revegetation Plan 71
11.2 EFR Responses to Rd I Interrogatory White Mesa RecPlan 5,0 R313-24-4; 10CFR40, Appendix A; INT
I I/l; Vegetation and Biointrusion Evaluation and Revegetation Plan 72
11.3 Division's Assessment of EFR Responses to Rd I Interrogatory White Mesa RecPlan Rev, 5,0; R313-24-4;
10CFR40, Appendix A; INT 1 l/I; Vegetation and Biointrusion Evaluation and Revegetation Plan 75
12,0 Report Radon Barrier Effectiveness 78
12.1 Round 1 Interrogatory White Mesa RecPlan REV 5,0 R313-24-4; I0CFR40, Appendix A, Criterion 6(4);
INT 12/1; Report Radon Barrier Effectiveness 78
12.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan 5.0 R313-24-4; 10CFR40, Appendix A,
Criterion 6(4); INT I2/I; Report Radon Barrier Effectiveness 80
TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
12.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev. 5.0; R313-24-4;
10CFR40, Appendix A, Criterion 6(4); INT 12/1; Report Radon Barrier Effectiveness 82
13.0 Concentrations of Radionuclides Other Than Radium 83
13.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; 10CFR40, Appendix A, Criterion 6(6);
INT 13/1; Concentrations of Radionuclides Other Than Radium 83
13.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan 5.0 R313-24-4; 10CFR40, Appendix A,
Criterion 6(6); INT I3/I; Concentrations of Radionuclides Other Than Radium 84
13.3 Division's Assessment of EFR Responses to Rd I Interrogatory White Mesa RecPlan Rev. 5.0; R313-24-4;
10CFR40, Appendix A, Criterion 6(6); INT 13/1; Concentrations of Radionuclides Other Than Radium ..89
To further resolve remaining issues pertaining to concentrations of radionuclides other than radium in soil, the
Division requests that EFR please do the following: 89
14.0 Cover Test Section and Test Pad Monitoring Programs 90
14.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; 10CFR40, Appendix A; INT 14/1; Cover
Test Section and Test Pad Monitoring Programs 90
14.2 EFR Responses to Rd I Interrogatoiy White Mesa RecPlan 5.0 R313-24-4; I0CFR40, Appendix A; INT
14/1; Cover Test Section and Test Pad Monitoring Programs : 91
14.3 Division's Assessment of EFR Responses to Rd I Interrogatory White Mesa RecPlan Rev. 5.0; R313-24-4;
10CFR40, Appendix A; INT 14/1; Cover Test Section and Test Pad Monitoring Programs 92
15.0 Financial Surety Arrangements .) 96
15.1 Round I Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; I0CFR40, Appendix A, Criterion 9; INT
15/1; Financial Surety Arrangements 96
15.2 EFR Responses to Rd I Interrogatory White Mesa RecPlan 5.0 R313-24-4; 10CFR40, APPENDIX A,
CRITERION 9; INT 15/1; Financial Surety Arrangements 97
15.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev. 5.0; R313-24-4;
10CFR40, Appendix A, Criterion 9; INT l'5/I; Financial Surety Arrangements 97
16.0 Radiation Protection Manual 98
16.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-15-501; 16/1; Radiation Protection Manual...98
16.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan 5.0 R313-15-501 INT 16/1; Radiation
Protection Manual , 98
16.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev. 5.0; R313-15-
501; INT 16/1; Radiation Protection Manual , 99
17.0 Response to Int White Mesa Recplan Rev 5.0 R313-15-1002; INT 17/1; Release Surveys 99
17.1 Round I Interrogatory White Mesa RecPlan Rev 5.0 R313-15-1002; INT 17/1; Release Surveys 99
17.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan 5.0 Rev 5.0 R313-15-1002; INT 17/1; Release
Surveys 99
17.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev. 5.0 R313-15-
1002; INT 17/1; Release Surveys 99
18.0 Response to Int White Mesa Recplan Rev 5.0 R313-12; INT 18/1, Inspection and Quality Assurance 100
18.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 5.0 R313-12; INT 18/1; Inspection and Quality
Assurance 100
18.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-12; INT 18/1; Inspection and
Quality Assurance 100
18.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev. 5.0 5.0 R313-
12; INT 18/1; Inspection and Quality Assurance 100
19.0 Response to Int White Mesa Recplan Rev 5.0 R313-24; 10CFR4.42(J); INT 19/1, Regulatory Guidance 101
TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
19.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24; 10CFR40.42(J); INT 19/1; Regulatory
Guidance ,., 101
19.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan 5,0 R313-24; 10CFR40,42(J), INT 19/1;
Regulatory Guidance 101
19.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev. 5.0 R313-24,
lOCFR 40.42(J); INT 19/1; Regulatory Guidance 101
20.0 Response to INT WHITE MESA RECPLAN REV 5.0 R313-24; 10CFR40, Appendix A, Criterion 6(6); INT 20/1,
Scoping, Characterization, and Final Surveys 102
20.1 Round I Interrogatory White Mesa RecPlan Rev 5.0 R313-24; 10CFR40 Appendix A Criterion 6(6); INT
O/I; Scoping, Characterization, and Final Surveys 102
20.2 EFR Responses to Rd I Interrogatory White Mesa RecPlan Rev 5.0 R313-24; 10CFR40 Appendix A
Criterion 6(6); INT 20/1; Scoping, Characterization, and Final Surveys 103
20.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev. 5.0 R313-24;
10CFR40 Appendix A Criterion 6(6); INT 20/1; Scoping, Characterization, and Final Surveys 109
REFERENCES 110
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
ATTACHMENT A Rev 5.0 Reclamation Plan Round 1
Interrogatories, Responses, and Discussion
1.0 Responses to Reclamation Plan Rev. 4.0 Interrogatories
1.1 Round 1 Interrogatory White Mesa Rec Plan Rev. 5.0; R313-24-4; 10CFR40.31(H);
INT 01/1; Responses to Reclamation Plan Rev. 4.0 Interrogatories
The interrogatory requested the following:
The Division has reviewed the responses to Reclamation Plan Rev. 4.0 and is not asking for
additional information at this time; however, the Division reserves the right and may submit
comments and/or additional interrogatories following completion of review of the Denison
Mines (USA) Corp (DUSA) response document dated December 28, 2011 (DUSA 2011).'
1.2 EFR Responses to Rd 1 Interrogatory White Mesa Rec Plan Rev. 5.0; R313-24-4;
10CFR40.31(H); INT 01/1; Responses to Reclamation Plan Rev. 4.0 Interrogatories
IN ITS RESPONSE, EFR noted that in their response to this interrogatory that no response was
required EFR noted, however, that in response to this interrogatory, that a facility-wide
inspection to determine the presence of asbestos in building materials in the milling facility
would be conducted for Denison in the Spring of 2012. EFR used a qualified contractor to
inspect the following four facilities at the White Mesa mill: Administration Building; Mill
Building, Boiler Plant, Scale House, and Sample Plant; Maintenance-Warehouse Facility; and
SXBuilding. These inspections identified (included in Attachment A to this Response) asbestos
containing materials (ACM) as follows:
• Administration Building - 9,745 square feet of floor tile and mastic
• Mill Building, Boiler Plant, Scale House, and Sample Plant - No ACM identified
• Maintenance- Warehouse Facility - 2,560 square feet of floor tile and mastic
• SX Building - 20 units of pipe fitting sealant
EFR's contractor estimated to cost to remove and dispose of all ACM to total less than $50,000,
not including technicians' travel expenses, cost for asbestos abatement design, and cost for
management consulting services. ^
25
TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
1.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa Rec
Plan 5.0; R313-24-4; 10 CFR40.31(H); INT 01/1; Responses to Reclamation Plan
Rev. 4.0 Interrogatories
The Division requests that EFR include the additional costs for removing the identified ACM in
the estimate of costs to decontaminate and decommission the mill. The Division will review the
revised reclamation cost estimates, when available, to verify that these costs have been included
in the reclamation cost estimates.
2.0 Engineering Drawings
2.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4; 10CFR40
Appendix A, Criterion 4; INT 02/1; Engineering Drawings
The interrogatory requested that EFR do the following:
Drav^ng REC-1: Provide design details for Discharge Channel.
Drawing REC-3: Provide design details for Discharge Channel. Identify the limits of the
proposed Sedimentation Pond.
Establish and indicate on the appropriate drawing(s) the location of the main drainage channel.
Demonstrate that the Cell 1 embankment and appurtenant apron are designed to remain stable
under PMP conditions.
Drawing TRC-2: Correct the location shown by green dashes for the "Approximate limit of
compacted cover,"
Drawing TRC-4: State where "Filter Layer" is defined. Link Rock Apron A and Rock Apron B
to characteristics presented in the table at Detail 1/8.
Drawing TRC-5: In Sections A/3 and B/3, indicate the cover thickness to be 9 feet minimum.
State the maximum tailings elevation on the North end of each section.
Drawing TRC-6: Please explain why the Compacted Cover cannot continue through the entire
sections rather that terminating as "wedges".
Drav^ng TRC-7: Please explain why the Compacted Cover cannot continue through the entire
sections rather that terminating as "wedges". State maximum slope on transitional slopes in
Section A/3, B/3, and C/3 to be 5:1. State maximum tailings elevations in each section.
Drawing TRC-8: Revise both the Plan and the Elevation of Detail 1/8 to refer to the table
provided below rather than stating D50 = 7.4" min. State where "Filter Layer" is defined. Show
the "Riprap Filter Layer" on the side slopes of Details 3/5, Detail 4/8, and Detail 5/8 or otherwise
resolve the conflict involving "Riprap Filter Layer" that exists between Detail 1/8 and the details
cited. State where "Clay Liner" called out in Detail 4/8 is defmed. Justify terminating the "Clay
Liner" shown in Detail 4/8 at the exterior extreme (of top) of the "Radon Attenuation and
Grading Layer". State the cover thickness shown in Detail 4/8 to be 9 feet minimum. Show the
correct maximum tailings elevations in Details 6/8v(presently incorrectly stated) and 7/8
(presently not stated).
26
TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
2.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4;
10CFR40 Appendix A, Criterion 4; INT 02/1; Engineering Drawings
IN ITS RESPONSE, EFR indicated that Denison conducted a field investigation on April 19,
2012 to supplement existing soils data and further evaluate the geotechnical properties ofthe
potential cover material. EFR indicated that laboratory testing on the collected samples from the
April 2012 investigation was done in two phases. Phase 1 testing included Atterberg limits,
specific gravity, and gradation (including hydrometer). Based on evaluation ofthe Phase 1
laboratory testing results for the April 2012 investigation and further evaluation of the
laboratory testing conducted on samples from the October 2010 investigation, in addition to
information provided by Benson (2012), the stockpile soils were categorized into four soil
categories. The categories included topsoil, fine-grained.soils, broadly graded soils, and
uniformly graded soils. Select samples from the April 2012 investigation from these categories
were selected for Phase 2 testing which included standard Proctor compaction, saturated
hydraulic conductivity, and moisture retention tests.
EFR stated that the results of the 2010 and April 2012 laboratory testing were used to revise the
technical analyses for the cover design, and that the resulting cover design is discussed in the
Responses to Interrogatory 12/1. EFR committed to update the Drawings to reflect the revised
cover design in the next revision of the Reclamation. EFR also provided narrative descriptions of
a series of changes it intends to make to engineering drawings:
"The Drawings will be updated to provide design details for the Discharge Channel and identify
the limits of the Sedimentation Pond.
The Cell 1 embankment and toe are designed to be erosionally stable from peak runoff from the
PMP. Erosion protection is provided by riprap on the reclaimed slope of the Cell 1 embankment,
and by a riprap apron at the toe of the embankment. The updated erosional stability analyses,
including for the embankment and toe apron, are provided in Attachment C as a revised
Appendix G that will be included in the next version of the Updated Tailings Cover Design
Report (Appendix D of the Reclamation Plan).
Cell I will be cleaned of contaminated materials upon reclamation and the materials will be
placed in the tailings cells. A portion of the Cell 1 area will be used for permanent disposal of
contaminated materials and mill debris. The remaining area of Cell 1 will be breached and
converted to a sedimentation basin. The Sedimentation Pond is designed to grade at a 0.1
percent slope northwest towards the Discharge Channel This area is designed to be erosionally
stable from peak runoff from the PMP with topsoil and vegetation. A rock apron is included at
the transition between the vegetated surface of the Sedimentation Basin and the bedrock surface
at the entrance of the Discharge Channel. Although channeling in this area would not cause
erosional issues for the Cell 1 embankment, Denison has revised the grading to include a
drainage swale along the center of the Sedimentation Pond area parallel to the toe ofthe Cell 1
27
TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
embankment and draining to the west towards the Discharge Channel as shown in Figure G. 1 of
Attachment C.
The location of the "approximate limit of compacted cover " will change due to revisions to the
cover design and the updated limit will be provided on Drawing TRC-2 in the next revision ofthe
Reclamation Plan after approval of the conceptual cover design. The compacted cover was
shown correctly as terminating as "wedges" on Drawings TRC-7 and8 in Reclamation Plan
Rev, 5.0. The compacted cover is the cover layer that will be compacted to 95 percent of
standard Proctor dry density In some areas of Cell 2 and 3, the placed interim cover is thicker
than required for the cover design and/or additional interim cover is required to meet grading
requirements. As a result, there are areas in Cell 2 and 3 that do not require the compacted
cover layer to meet radon emanation requirements. This is discussed further with the revised
radon modeling results provided in Attachment H. A minimum compacted layer will be included
for the final design and the drawings will be updated to incorporate this change as well as the
revised cover design. A note will be added to the drawings to provide additional clarification.
Notes will be added to Drawing TRC-4 to clarify details on the filter and aprons provided on
Drawing TRC-8. ^
A minimum cover thickness will be added to Drawing TRC-5 for Sections A/3 and B/3. The
maximum tailings elevation will be added to the north end of Sections A/3 and B/3.
The maximum transitional slopes will be stated as 1 OH:IVon Drawings TRC-6 and TRC-7.
Drawing TRC-8 will be revised to reference the table for the Plan and Elevation of Detail 1/8.
The filter layer and clay liner will be defined on Drawing TRC-8. The riprap filter layer will be
added to the Details 3/5, 4/8, and 5/8. The termination ofthe clay liner will be revised to
terminate at the bottom of the radon attenuation and grading layer and a 3-ft berm will be
added at the termination location. The minimum cover thickness will be added to Detail 4/8. The
maximum tailings elevations will be corrected for Detail 6/8 and will be added to Detail 7/8. "
2.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev 5.0 R313-24-4; 10CFR40 Appendix A, Criterion 4; INT 02/1;
Engineering Drawings
1. Based on review of the above Response, the Division finds that although EFR
provided narrative descriptions of the changes it intends to make to engineering
drawings, revised drawings were not submitted with interrogatory responses.
Rather, EFR committed to provide revised engineering drawings with the "next
revision of the Reclamation Plan". The Division will review the revised engineering
drawings, when available, to verify that these changes to the drawings have been
made. Because EFR submitted neither revised engineering drawings nor the revised
Reclamation Plan in its interrogatory response, this interrogatory will remain open.
28
TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
3.0 CQA/CQC Plan, Cover Constructability, and Filter and i^ock Riprap Layer
Criteria and Placement
3.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4; 10 CFR 40
Appendix A, Criterion 1 and 4; INT 03/1; CQA/CQC Plan. Cover Constructability,
and Filter and Rock Riprap Laver Criteria and Placement
The interrogatory requested that EFR do the following:
Refer to Section 5 of Attachment B, Construction Quality Assurance/Quality Control Plan, to the
Reclamation Plan, Rev. 5.0: Please provide the following:
1. In Sections 5.3 and 5.4, clarify the nature and characteristics of wastes that would be
placed into the reclaimed Cell 1 footprint area within which the 1-foot-thick compacted
clay liner would first be installed. Verify whether and state consistently throughout the
CQA/CQC Plan whether any uranium mill tailings materials would be placed into the
clay-lined Cell 1 footprint area. If no tailings will be placed in the Cell 1 area, then
change the name ("Cell 1 Tailings Area") given in the T.O.C., and Sections 1.1, 5.3,
5.4.2, and 5.6 ofthe CQA/CQA Plan to "Cell 1 .Contaminated Soil and Demolition
Debris Disposal Area" or other name as appropriate, and revise the descriptions of waste
materials to be placed into the clay-lined Cell 1 area as needed throughout the CQA/CQC
7 Plan to be consistent with the proposed disposal plan.
2. In Sections 5.6.4 and 5.6.5, provide a detailed justification to support the technical
appropriateness and the constructability of the proposed topslope areas of the proposed
cover system having such extremely flat slopes (e.g. 0.1 to 0.82 %). Provide information
demonstrating that such topslope areas of the cover could be constructed with such
shallow inclinations maintained continuously over the long distances that are required
based on the currently proposed over design drawings such that no areas of runoff
concentration or areas where ponding or could occur would result. Provide information
justifying that appropriate required tolerances specified for final grades for ensuring
conformance to the proposed extremely flat slope inclinations can be maintained and
measured in the field with sufficient accuracy to ensure compliance with the specified
slope requirements.
3. In Section 5.7.1.2, described material sampling frequency and filter gradation and filter
permeability calculations (with associated acceptance criteria) that will be performed for
the granular materials used in constructing the granular filter layer beneath the riprap
layer on the sideslopes, to ensure that all applicable filter acceptance criteria will be
^ achieved between the granular filter layer and each topslope cover layer component.
4. In Section 5.7.1, specify the minimum required thickness of the rock riprap layer on the
sideslopes - equal to 1.5 times the D50 of the rock rip diameter of 7.4 inches, or the Dioo
of the rock rip rap materials, whichever is greater, as per NUREG-1623 (NRC 2002) -for
clarity and transparency in the CQA/CQC process.
5. In Sections 5.7.2, 5.7.4, and 5.7.5 provide additional details regarding the minimum
thickness for placed riprap layer material and requirements for using specialized
29
TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
equipment or rearranging of rocks by hand, as needed, in accordance with the specified
minimum required final thickness of the rock rip rap layer. Also provide additional
details and requirements regarding procedures to be used to verify proper in-place rock
riprap layer thickness and procedures for gradation testing in a completed initial riprap
layer section, and for visual observations of the test section by field personnel. Provide
criteria and procedures for testing additional test sections where observations suggest
rock placement appears to be inadequate or where difficulties are experienced during
rock place activities.
3.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4;
10CFR40 Appendix A, Criterion 4; INT 03/1; CQA/CQC Plan, Cover
Constructabilitv. and Filter and Rock Riprap Layer Criteria and Placement
IN ITS RESPONSE, EFR provided the following information:
CQA/CQC Plan - EFR indicated that they will revise all sections of the CQA/CQC Plan,
Technical Specifications, and the text of the Reclamation Plan itself to preclude placement of
tailings into the Cell I Disposal Area, and to identify the Cell 1 area as the "Cell I Disposal
Area " in all documents. EFR indicated that materials to be placed into this area will consist of
contaminated materials and mill decommissioning debris.
Cover Constructability - EFR provided the following list of eight reclaimed uranium mill tailings
repositories in the U.S. where either cover slopes or portions of cover slopes have been
constructed at inclinations less than 1 %:
Falls City Title I site in Texas (less than 1% cover slopes)
Bluewater Title II site in New Mexico (0.5 - 4% cover slopes)
Conquista Title IIsite in Texas (0.5-1% cover slopes)
Highland Title II site in Wyoming (0.5 - 2% cover slopes)
Panna Maria Title II site in Texas (0.5% cover slopes)
Ray Point Title IIsite in Texas (0.5-1% cover slopes)
Sherwood Title II site in Washington (0.25% cover slopes)
L-Bar Title II site in New Mexico (0.1% cover slopes)
EFR also referred to a revised settlement analysis they completed in response to Interrogatory
07/01 (part of this Round 1 Response package) that indicated the following:
" the majority of the total settlement due to final cover placement and creep will occur within the
first five years after placement of the final cover. During this time period, additional fill can be
placed in any low areas in order to maintain positive drainage of the cover surface. Settlement
occurring over five years after placement of the final cover ranges from 0.52 to 0.83 feet, with a
maximum potential total differential settlement on the order of 0.31 feet. This estimated
settlement is sufficiently low such that ponding is not expected to occur with a cover slope of 0.5
30
TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
percent. In addition, it is not expected that the differential settlement is significant enough for
slope reversal to occur. "
Said response also included the following assessment:
"Cover cracking analyses were evaluatedfor the highly compacted radon barrier for the timer
period after placement of the final cover. . . . The horizontal movement at the maximum tailing
thickness is calculated to be 0.028feet using a maximum thickness of relatively incompressible
material of 4.7 feet, and a total differential settlement of 0.9 feet over 100 feet. The thickness of
relatively incompressible material was estimated assuming a maximum 4.7-ft highly compacted
radon harrier. The horizontal strain between any two settlement monitoring locations is the
maximum horizontal movement divided by the horizontal distance (0.028ft/100 ft). Using these
values, the maximum horizontal strain is calculated as 0.028 percent. This value is lower than
the maximum allowable strain of 0.05 percent. This indicates that cracking of the radon
attenuation layer is not likely.
r
IN ITS RESPONSE, EFR provided additional filter gradation criteria in Attachment C to this
Response package and indicated that Section 5.7.1.2 of the CQA/CQC Plan will be revised to
include a testing requirement for particle size distribution testing prior to placement, using
ASTM D-422. The recommended testing frequency is at least one test per 10,000 cubic yards of
filter material placed, or when filter material characteristics show significant variation.
IN ITS RESPONSE, EFR indicated that Section 5.7.1 ofthe CQA/CQC Plan and Section 8.2.4 of
the Technical Specifications will be revised to include a required minimum thickness ofthe rock
riprap layer equal to 1.5 times the D50 rock riprap diameter of 7.4 inches, or the Djoo of the rock
riprap materials, whichever is greater.
In its RESPONSE, EFR also indicated the following:
• Sections 5.7.2 and 5.7.4 of the CQA/CQC Plan will be revised to include reference to Section
5.7.1 for the minimum required thickness for the riprap layers (see Response 4 above).
• Section 5.7.2 of the CQA/CQC Plan will be revised to include the following text at the end of
the section "Hand placing will be required only to the extent necessary to secure the results
specified above."
• , Section 5.7.4 of the CQA/CQC Plan will be revised to include the following text at the end of
the section "Riprap layer thickness will be directly measured as outlined in Section 5.7.2. A
measurement device (le. tape measure) may be used to determine the distance from the top
ofthe bedding or filter layer to the top of the riprap layer. "
• Section 5.7.2 of the CQA/CQC Plan will be revised to include the following text "An initial
section of each type of riprap constructed shall be visually examined and used to evaluate
future riprap placement. The initial section will be constructed with material meeting
gradation and riprap thickness requirements; and
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
• Section 5.7.1.1 of the CQA/CQC Plan will be revised to include the following text at the end
ofthe section "Gradations will also be performed at the direction of the QC Technician for
any locations considered inadequate based on visual inspection by the QC Technician, or if
difficulties are experienced by the Contractor during rock placement. "
3.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa Revised
RecPlan 5.0; R313-24-4; 10CFR40 Appendix A, Criterion 4; INT 03/1; CQA/CQC
Plan. Cover Constructability, and Filter and Rock Riprap Layer Criteria and
Placement
The Division finds EFRs' Response to the first item of this interrogatory pertaining to
materials to be placed into Cell 1 - i.e., EFR's commitment to revise all sections of the
CQA/CQC Plan, Technical Specifications, and the text of the Reclamation Plan itself to
preclude placement of tailings into the Cell 1 Disposal Area, and to identify the Cell 1 area
as the "Cell 1 Disposal Area" in all documents - to be acceptable. These revised documents
will need to be reviewed, when available, to verify that these changes have been made.
Because these revised documents were not submitted in its interrogatory response, this
interrogatory will remain open.
Based on its review of the section of EFR's response pertaining to the constructability of
the currently proposed cover system having such extremely flat topslope inclinations, the
Division is unable to concur with EFR's contention that such flat inclinations can be
constructed uniformly and reliably over the entire required topslope area, as insufficient
supporting information and justification have been submitted to satisfactorily support the
contention. This issue needs to be addressed before appropriate conclusions can be
reached.
In addition to the Division's uncertainties related to the constructability of the currently
proposed cover, insufficient information has been provided in Attachment A (Technical
Specifications, Section 8) and Attachment B (CQA/CQC Plan, Section 6) to the Rev 5.0
Reclamation Plan or in EFR's response regarding the means and procedures that would be
implemented for controlling, verifying, and documenting layer thicknesses and final grades
across the top portions of the cover. Examples of information missing that should be
provided are discussions regarding the need for use of Global Positioning System (GPS)
and computer terrain modeling technology and how these might be combined to provide
for a Computer Aided Earthmoving System (CAES) for verification of soil compaction and
thicknesses of layers as they are being installed and undergoing compacted during each
pass of the compaction equipment over placed loose lifts (e.g.. Caterpillar 2003). The
advantage of this methodology is that it provides a continuous record in a continuous
manner across the entire cover area footprint, rather than acquiring data at a series of
isolated points. Discussions of soil density tests and independent land surveys for
demonstrating the effectiveness of the CAES method, and procedures that may be used for
visual monitoring of the CAES-verified compaction process and review of CAES-generated
computer records for each layer of soil placed by on-site QC personnel, should also be
provided. A more detailed discussion should also be provided of companion sand cone tests
and moisture tests to be performed along with nuclear tests until a sufficient number of
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
have been performed to demonstrate a clear correlation between results obtained using
these test methods. Similar procedures to those described here have been accepted and are
in use at the Crescent Junction, Utah uranium tailings repository (e.g., see U.S. DOE-
EM/GJ1547 [DOE 2012]).
The Division finds the filter layer gradation and permeability criteria and proposed
construction quality assurance testing procedures and frequencies to be acceptable. The
revised CQA/CQC Plan will need to be reviewed, when available, to verify that these
changes have been made. Because the revised CQA/CQC document was not submitted in
its interrogatory response, this interrogatory will remain open.
The Division also finds EFR's commitment to revise Section 5.7.1 of the CQA/CQC Plan
and Section 8.2.4 of the Technical Specifications to include a required minimum thickness
ofthe rock riprap layer equal to 1.5 times the D50 rock riprap diameter of 7.4 inches, or
the DIOO ofthe rock riprap materials, whichever is greater, to be acceptable. The revised
CQA/CQC Plan and revised Technical Specifications will need to be reviewed, when
available, to verify that these commitments will be faithfully implemented. Because these
revised documents were not submitted in its interrogatory response, this interrogatory will
remain open.
Based on review of the information provided in the Response with respect to rock riprap
placement and construction qualify assurance testing, the Division notes that EFR did not
address certain additional specific recommendations included in Appendix F (Rock
Placement Procedures for Erosion Protection) of NUREG-1623 (NRC 2002) in their
response to this interrogatory, but which should be addressed. Additional NUREG-1623
recommendations that should also be addressed/ implemented include the following:
• Initial testing should be conducted to determine the gradation and the rock
weight/unit volume that will be achieved in future rock placement activities.
• No individual rock piece should exceed 90% of the riprap layer thickness
• Dumped riprap should be placed to its full course thickness in one operation and in
such a manner as to avoid displacing any underlying bedding material
• It should be declared that rearranging of individual stones by mechanical
equipment or by hand may be required to the extent necessary to obtain a well-
keyed and reasonably well-graded distribution of stone sizes and that larger pieces
of riprap may require individual placement by equipment.
• Any stones that are not firmly wedged should be adjusted and additional selected
stones inserted or existing stones replaced, so as to achieve a solid interlock.
Based on its review of the section of EFR'S response pertaining to settlement and of the
referenced revised settlement analyses, the Division is unable to assess the correctness of
EFR's conclusion regarding cover performance with respect to settlement due to errors,
omissions, discrepancies, and insufficient information in the materials submitted. These
issues need to be addressed before appropriate and reliable conclusions can be reached.
These issues are more fully discussed in Sections 7.0 and 9.0 below relative to the response
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
to Interrogatory 07/01, Technical Analysis - Settlement and Potential for Cover Slope
Reversal and/or Cover Layer Cracking and 09/01, Technical Analysis - Liquefaction.
Evidence should also be provided that the eight UMTRCA repository sites (which EFR
claims have slopes similar to the 0.5 to 1% slopes proposed for the subject site) have
performed adequately and that demonstrates that future differential settlement of those
repositories during the 200-1,000 -year performance period of those facilities will not
occur to a degree that flattening/slope reversal of the topslope portions of those covers
\yould result. Such information should include currently observed differential settlements
and predictions of future settlements calibrated to the observed performance.
4.0 Void Space Criteria for Debris, Rubble Placement, and Soil/Backfill
Requirements
4.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4; 10CFR40,
APPENDIX A, Criterion 4; INT 04/1; Void Space Criteria for Debris. Rubble
Placement, and Soil/Backfill Requirements
The interrogatory requested that EFR do the following:
Refer to Section 6.0 of Appendix G and Section 7.0 of Attachment A (Technical Specifications)
of the Reclamation Plan, Rev. 5.0:
a. Please define and justify a maximum void space percentage that will be allowed
when disposing of demolition and decommissioning debris fragments and rubble
in Cell 1.
b. Describe, in detail, construction practices that will enable satisfying this specified
limit;
c. Please provide detailed procedures that will be used to control residual voids to
meet the specified maximum allowable void space percentage(s) and a description
of the specific construction quality assurance / quality control and verification
procedures to be used to demonstrate that the void space criteria will be achieved;
d. Demonstrate how the percentage of allowable void space relates to the settlement
analyses performed to evaluate the effectiveness of the procedures for placing
debris fragments and rubble, placement of backfill in/around/under debris items,
and compaction of the debris/backfill materials, for precluding the potential for
slope reversal in the Celll cover system. Please also refer to "INTERROGATORY
WHITEMESA RECPLAN REV. 5.0; R313-24-4; 10CFR40 APPENDIX A; INT
07/1: TECHNICAL ANALYSIS - SETTLEMENT AND POTENTIAL FOR
COVER SLOPE REVERSAL AND/OR COVER LAYER CRACKING";
e. Please further define the characteristics of, and estimate the percentage of organic
materials (including, for example, wood, branches, roots, paper, and plastic),
expected to be disposed of Provide specifications and procedures for disposing of
organic materials such that long-term biodegradation of the disposed organic
materials will not compromise the integrity and stability of the cover system;
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
f Please provide detailed specifications for segmenting and placing metallic waste
materials in layers so that structural shapes or other large pieces will not lie across
or on top of each other. Please indicate that placement of metallic materials will .
allow large voids to be minimized and filled with soil. Please address special
handling and disposal procedures for oversized and/or odd-shaped steel materials,
including cutting or trimming dimensions before positioning for burial, and
placement procedures to ensure that no large "slip planes" will occur within the
disposal mass. Specify maximum allowable lift thickness for such material
placement. Please also describe shredding, cutting or trimming procedures required
to ensure that such materials following shredding, cutting or trimming can be
placed within the specified allowable layer thickness; ,
g. Provide additional details of type of materials and placement practices, including
specific dimensions of all demolition debris expected to be disposed of in Cell 1.
Please justify that items needing to be size-reduced prior to disposal will in fact be
size reduced. Provide additional information to justify that a maximum allowable
size of dismantled or cut materials of 20 feet in the longest dimension (as
proposed) and a maximum volume of 30 cubic feet are acceptable criteria for
placement of such objects in a disposal cell;
h. Please provide a contingency plan to address the situation in which an insufficient
quantity of demolition debris and rubble and contaminated soil would be available
to fill the Cell 1 footprint area to a sufficiently high final waste grading
configuration to provide a smooth, continuous transition between the completed
Cell 1 cover system and the Cell 2 cover system, with no sudden, abrupt changes
in slope between the two cover systems. Discuss means and methods that will be
used, regardless of achieved final debris/rubble/contaminated soil placement
grades, for ensuring that a smooth cover slope transition will occur between these
two cell area cover systems;
i. Clearly and consistently define procedures/specifications for backfilling of interior
void spaces inside debris objects (e.g., backfill of insides of smaller segmented
pipe sections). Rectify apparent current inconsistencies between descriptions of
backfill materials proposed for such use as described in Attachment A (e.g.,
controlled low-strength materials [CLSM] or flowable fill) and backfill materials
for this use as described in Appendix (random fill materials). Provide rationale for
selecting preferred backfill materials (e.g., CLSM) for different types and/or sizes
of intemal void space, as appropriate. For CLSM/ flowable fill, etc... used,
provide information on the minimum required compressible strength of the
material; and
j. Describe how the compressive strength requirement for CLSM or other grout
backfill, in conjunction with the void space backfilling requirements and ultimate
allowable void space and organic waste percentages relate to the design objectives
for minimizing settlement of the backfilled Cell 1 area debris/rubble/backfill mass
to preclude the possibility for long-term cover slope reversals.
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
4.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4;
10CFR40, APPENDIX A, Criterion 4; INT 04/1; Void Space Criteria for Debris.
Rubble Placement, and Soil/Backfill Requirements
IN ITS RESPONSE, EFR responded individually to the ten issues raised in this interrogatory, as
follows:
Response la (a) -The procedures for sizing and placement of debris were developed from mill
demolition and debris placement at other uranium mill sites in the western US. The procedures
refiected in the Technical Specifications were based on whether the demolition materials were
compressible. These procedures are incorporated in the Technical Specifications, as summarized
below.
Compressible materials are to be crushed and covered with soils, and incompressible materials
are to be placed in the cell, with the void spaces outside of the materials filled with soils. Internal
void spaces of incompressible materials are to be filled with soil where possible, or grout if
needed.
Materials such as pipe and tubing have a varying degree of compressibility, depending on the
diameter and wall thickness of the pipe. Pipe with a 12-inch diameter or larger is to be filled
with grout or soil for burial, and pipe with smaller diameter was crushed before burial
(
A requirement for the maximum void space percentage is not included because there is no
practical method for measuring this percentage in the placed debris or the compacted soil
during or after placement Therefore a method specification reflecting best management practice
from other projects was incorporated in the Technical Specifications.
Response lb (b) - The debris is to be spread in a layer such that structural shapes or other large
pieces do not lie on across or on top of each other, to prevent nesting. The soil to be used for
filling voids around the debris is to be spread in loose layers over the debris, and worked into
and around the debris materials until the void spaces are minimized. Enough soil should be
placed so that the surface is accessible with tracked equipment The debris is then walked with
heavy tracked equipment to compress the debris as much as possible into the underlying soil
After additional soil fill placement, the soil and debris lift can be compacted with compaction
equipment. From the proposed specifications:
"The debris, contaminated soils and other materials for the first lift will be placed to a depth of
up to four feet thick, in a bridging lift, to allow access for placing and compacting equipment
The first lift will be compacted by the tracking of heavy equipment, such as a Caterpillar D6
Dozer (or equivalent), using at least 4 passes, prior to the placement of the next lift Subsequent
lifts will not exceed 12 inches and will be compacted using a minimum of 4 passes with the
tracked equipment or a vibratory compactor.
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
The CQA technicians will monitor and approve of the final debris placement. In areas where
voids are observed during placement, the contractor shall reexcavate the area, fill any voids ,
encountered with soil and recompact the materials, or grout the voids. " ^
Vessels and tanks will either be crushed (if thin-walled and compressible) or cut open (if thick-
walled and incompressible). Vessels that are to be cut open and filled, will be placed in the cell
such that fill can also be placed around them and compacted For thick-walled tanks or vessels
that cannot be cut open due to cutting difficulties or worker health concerns with cutting these
items open, these' tanks or vessels will be placed in the designated area of disposal, with interior
voids spaces grouted full.
Response Ic (c) - Quality assurance observation during fill and debris placement must be used
to monitor the occurrence of voids that will require additional material to fill, or additional
compaction of the debris layer. The contractor must ensure that debris is size-reduced to meet
the specifications, so that it can be placed in the cell efficiently and without nesting or the
occurrence of large voids. The Contractor will be required to repetitively attempt to make passes
over the debris and fill voids with soil until the QA staff has determined that the voids are
adequately filled, or an alternate method such as grouting will be required. The QA staff will
make a recommendation to the Contractor for the implementation of a grouting program in
instances when voids, either within a debris mass, or within a vessel cannot be properly filled
with soil using conventional equipment.
Response Id (d) - Limiting the percentage of allowable void space within the debris fill will
minimize the resulting settlement caused by the consolidation of the debris mass and the
potential for slope reversal However, the in-situ void characteristics of debris mass consisting
of concrete and steel of various shapes and sizes, can be difficult to quantify for settlement
analyses. The settlement analyses and any correlation to the percentage of voids within the
debris will be discussed further in responses to that interrogatory.
It should be noted that the cover on top of the disposal cell will not be placed until settlement ^
monitoring of the subsurface shows that anticipated settlement has taken place.
Response le (e) - The percentage of organic materials to be disposed of is anticipated to be a
small percentage of the total material being disposed. Because the quantity of organics for
disposal is minimal and because these materials are likely be mixed with incompressible debris
and soil the biodegradation of these materials is not anticipated to compromise the integrity of
the cover system. Additionally, the organic materials will be spread throughout the disposal area
which will minimize concentrated areas of compressible organic materials.
Organic debris should be size-reduced by crushing, chipping, or shredding prior to placement.
As described in the Technical Specifications, organic material should only be placed in lifts less
than 12 inches thick and should be mixed with the soil and other incompressible debris during
placement to prevent pockets of organic material from being created. Organics mixed with soil
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
for spreading should be limited to 30% by volume of the mixture. This limit will be added to the
Technical Specifications. ^
Response If (f) - The Contractor will select and place metallic debris by sizes so that larger
pieces are not stacked on top of each other at angles. Large structural shapes will either be laid
edge to edge so that they can be covered by soil that will fill in open spaces or they must be
spaced far enough apart that equipment can operate between them to compact fill As stated in
the Technical Specifications, long structural (incompressible) members will be oriented
horizontally. Metallic materials will be size reduced before placement and burial to a maximum
dimension of 20 feet and a maximum volume of 30 cubic feet. Any metallic materials exceeding
the specified dimensions will be cut or trimmed until they meet this specification.
Response Ig (g) - At this time the specific dimensions of all demolition debris expected to be
disposed of is not available. These maximum allowable sizes of cut or dismantled materials have
been specifiedfor demolition of multiple uranium mill sites in the western US. While the
specified maximum dimensions of 30 cubic feet, 20 feet for debris, and 10 feet for pipe, may be
larger than the references cited (DOE, 1995, 2000), typically demolition is sized for the haulage
equipment and often the individual pieces of debris will be less than these maximum dimensions
in order to fit in trucks. Debris objects approaching 20 feet in length or 30 cubic feet are most
likely to be long slender shapes which will have to he laidflat for disposal or they are large
blocky, or open vessel objects, which will be filled for placement In either case, it is the method
of placement in the cell and controlling the lift thickness, rather than the dimension ofthe debris
that will determine the potential for excessive void spaces.
The references cited by the reviewer describe limiting the maximum volume to 27 cubic feet
however only one of the references cited (DOE, 1995) includes a maximum dimension of 10 feet.
The second reference, specifications for Weldon Springs Disposal Facility (DOE, 2000) does not
include a maximum dimension for metal waste or large metal pieces, it states only that pipe
stockpiled "...has been cut to 10 feet or less... " Based on our experience at other sites, and the
review of the cited specifications, the proposed maximum length of 20 feet falls within the range
of maximum lengths specified by the cited specifications. The proposed specifications include a
maximum dimension of 20 feet for all debris and a 10-foot maximum dimension for pipes.
Response Ih (h) - If sufficient debris, rubble and contaminated soil is not available to fill Cell 1
as designed, the footprint of Cell 1 can be reduced in size so that the horizontal dimension
extending out from the Cell 2 is reduced and the lateral extent of the disposed materials is
reduced to he closer the base of the Cell 2 impoundment. This would allow the height ofthe cell
to be maintained and the volume reduced, so that the cover slopes, as designed, will create a
smooth, positive sloping transition from the Cell 2 to Cell 1. While it is unlikely that the volume
of contaminated soil will be insufficient, if additional fill is needed to raise the elevation above
the disposed material clean fill could be used to establish proper positive drainage on the cover.
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
Response li (i) - The proposed procedure for filling void spaces, either within vessels, pipes that
cannot be crushed (with a diameter of larger than 12 inches), or other miscellaneous voids, is to
first attempt to fill the voids with soil This would be done in the case of vessels by either placing
soil through an existing opening, or cutting them open so that soil can be placed using the bucket
of an excavator. Pipe sections, that cannot be crushed flat, can be cut short enough to stand on
their ends, and then filled with soil from the bucket of an excavator.
To rectify the discrepancy between Attachment A and Appendix G, the language in the
specification Section 7.3.6 of the Technical Specifications will be modified as follows:
"The voids on the inside of the item shall be filled with contaminated soil clean fill soil or grout
(controlled low-strength material, flowable fill etc.). Contaminated soil (Section 7.3.3) or clean
fill will be placed outside ofthe items and compacted with standard compaction equipment
(where possible) or hand-operated equipment to the compaction requirements in Specification
Section 7.4."
For debris where internal voids cannot practically be filled with soil a grouting program would
be initiated to pump controlled low strength material (CLSM, flowable fill) into the voids. Debris
would be grouped together and characterized as materials that would require grouting, so that a
significant volume of debris can be grouted in a single action, rather than grouting individual
lengths of pipe. Pipe sections could be stacked horizontally, or cut short enough to stand
vertically in a safe manner. Grout would then likely be batched offsite and delivered to the site
and a pump truck would likely be required to place the material within the debris, within the cell
A soil berm would be used to contain the grout laterally around the perimeter of the selected
debris. The debris voids would be grouted, and grout would also be placed around the debris to
develop a monolithic grouted mass.
The specified unconfined compressive strength of the CLSM would be between 30 psi (minimum)
and 150 psi (maximum). Unit weights on the order of 100 to 120 pcf will be specified. These
requirements will be added to the specifications.
Response Ij (j) - If CLSM is requiredfor the grouting of voids that cannot he filled mechanically
with soil the mix design for the grout should mimic, as closely as possible, the strength and
hydraulic properties of the contaminated soil that will also be used for filling voids within the
debris. This will minimize any effects of differential settlement that would result from the grout
having a higher strength and being less compressible than the surrounding soil
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
4.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev 5.0 R313-24-4; 10CFR40, APPENDIX A, Criterion 4; INT 04/1; Void
Space Criteria for Debris. Rubble Placement, and Soil/Backfill Requirements
The Division's assessments of these responses are summarized below.
a. Maximum Void Space Percentage: EFR does not state a maximum allowable void
space due to the lack of practical means of quantifying residual void space following
placement and backfilling. In lieu of stating a void space limit, EFR incorporates
practices and requirements that were developed for the UMTRAP/UMTRCA and
FUSRAP projects and that have been demonstrated effective in limiting settlement.
EFR has developed and will implement method specifications that reflect best
management practices, as documented in Attachment A "Plans and Technical
Specifications for Reclamation of White Mesa Mill Facilify; Blanding, Utah".
The practices call for compressible materials to be crushed or covered with soils
(thus reducing residual void space), while voids in and around incompressible
materials will be filled with soils or, if needed, grout.
The Division judges these specifications to be acceptable.
b. Construction Practices: Processing, placement, backfilling, and compacting of
debris and organic material are discussed in Sections 7.3 and 7.4 of Attachment A
"Plans and Technical Specifications for Reclamation of White Mesa Mill Facilify;
Blanding, Utah". According to these specifications:
• Some larger items and items with internal voids will be size reduced to expose
voids so they can be filled.
• Debris items will be placed to minimize nesting that could lead to residual voids
after backfilling.
• Compressible debris will be flattened or crushed.
• Voids will be backfilled with soil, sand, or grout as judged appropriate by CQA
Manager.
These specifications constitute current best management practices and we judge
them to be acceptable given current state of knowledge.
c. Controlling Residual Voids: EFR's QA staff will observe construction practices to
ensure that specifications for reducing void space within debris are met. The
interrogatory response includes a statement that "The QA staff will make a
recommendation to the Contractor for the implementation of a grouting program in
instances when voids, either within a debris mass, or within a vessel, cannot be
properly filled with soil using conventional equipment".
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
No reference to a "grouting program" exists in Attachment A "Plans and Technical
Specifications for Reclamation of White Mesa Mill Facilify; Blanding, Utah". Attachment
A should be revised to formalize this commitment.
d. Effects of Void Space on Settlement Analyses: EFR's response is given in its
response to INT 07/1. EFR's response notes that the cover system will not be
constructed "... until settlement monitoring of the subsurface shows the anticipated
settlement has taken place."
An additional criterion should be added requiring that observed settlement has stabilized
according to some reasonable criterion.
e. Percentage of Organic Materials: EFR's response makes several statements that, as
far as we are able to determine, are not supported or documented:
• "The percentage of organic materials to be disposed of is anticipated to be a
small percentage of the total material being disposed."
• "... the biodegradation of these materials is not anticipated to compromise the
integrify of the cover system."
EFR should provide additional information to support these statements and provide
confidence that the integrify of the cover system will not be compromised.
1. Segmenting and Placing Metallic Waste Materials: Section 7.3 of Attachment A
"Plans and Technical Specifications for Reclamation of White Mesa Mill Facilify;
Blanding, Utah" requires that larger debris items be size reduced, that larger pieces
are not stacked on top of each other, that large structural shape either be placed
edge to edge or spaced far enough that voids can be filled and equipment can
operate between them, that the maximum dimension be 20 feet, that the maximum
volume of any piece of debris be 30 cubic feet, and that long structural members be
placed horizontally, and that any piece not satisfying these requirements be
reworked.
These provisions are considered acceptable.
1. Types of Materials and Placement Practices: Section 7.3 of Attachment A "Plans
and Technical Specifications for Reclamation of White Mesa Mill Facilify;
Blanding, Utah" places limits of 20 feet in length and 30 cubic feet in volume.
Although the interrogatory response mentions a maximum pipe length of 10 feet, this limit
is not stated in the Attachment A. EFR should revise Attachment A to state the maximum
pipe length if it is less than 20 feet.
f. Relative Quantities of Debris, Rubble, and Contaminated Soil: EFR should revise
Attachment A to address the possibilities mentioned in the interrogatory response,
should relative quantities of debris, rubble, and contaminated soil not allow Cell 1 to
be closed as planned.
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
g. Backfilling Voids Inside Debris Objects: EFR proposes to revise Attachment A to
incorporate the statement "The voids on the inside of the item shall be filled with
contaminated soil, clean fill soil, or grout (controlled low-strength material, flowable
fill, etc.). Contaminated soil (Section 7.3.3) or clean fill will be placed outside of the
items and compacted with standard compaction equipment (where possible) or
hand-operated equipment to the compaction requirements in Specification Section
7.4." EFR also describes measures that could be taken to ensure that voids inside
debris items are filled. These include:
• Filling the voids with soil through an existing opening
• Filling the voids with soil by cutting the item open
• Crushing the item flat (so no voids remain within
• Cutting pipes short, standing them on end, and filling them with soil
• Pumping controlled low-strength material (CLiSM or grout) into a region to
form a monolithic grouted mass
These proposed revisions are acceptable and should be incorporated into Attachment A as
proposed and other documents as appropriate.
h. CLSM Compressive Strength Requirements: EFR states that grout, if required, will
be formulated to "mimic, as closely as possible, the strength and hydraulic
properties of the contaminated soil that will also be used for filling voids within the
debris."
EFR should state more specifically how these properties will be achieved and what
formulation is likely to produce the desired outcome.
5.0 Seismic Hazard Evaluation
5.1 Round 1 Interrogatory White Mesa RecPlan 5.0 R313-24-4; 10CFR40, Appendix A;
INT 05/1; Seismic Hazard Evaluation
The interrogatory requested the following:
Refer to Appendix E and Attachment E.l to Appendix E to Appendix D, Updated Tailings
Cover Design Report of the Reclamation Plan, Rev. 5.0: Please provide the following:
1. Please further clarify the rationale for selecting the annual probability of exceedance of
hazard for the facility.
2. Adjust the cited USGS Nafional Hazard Map PGA (peak ground acceleration) value of
0.15 g for the site Vs30 as appropriate.
3. Explain why the calculated hazard for the background earthquake PGA of 0.24 g was
estimated but ignored in the recommendations provided in Appendix E.
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
4. Provide information to justify the use of 15 km distance for a background eeirthquake Mw
6.3 event.
5. Perform and report results of a site-specific probabilistic seismic analysis in lieu of using
the USGS National Hazard Maps for developing site-specific seismic design parameters.
5.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan 5.0 R313-24-4;
10CFR40, Appendix A; INT 05/1; Seismic Hazard Evaluation
IN ITS RESPONSE, EFR indicated that previous seismic hazard analyses for the site evaluated
peak ground acceleration (PGA) at the site for the operational life (MFG, 2006) and long-term
reclaimed conditions (Tetra Tech, Inc. (Tetra Tech) 2010). The seismic hazard analysis by MFG
(2006) compared the results of a deterministic seismic hazard analysis (DSHA) to USGS
National Seismic Hazard Maps showing the peak ground acceleration (PGA) associated with a 2
percent probability of exceedance in 50 years, or a return period of2,475 years. The projected
operational lifetime of the most recently constructed tailings cell at the site is estimated to he
approximately 50 years, from the time of construction through the time when the cell will have
been dewatered and reclaimed. Therefore, use off a 2,475-year return period in formulating the
probabilistic operational design criteria is considered conservative as this event has a 2'percent
probability of exceedance over the anticipated 50-year operational design life.
EFR indicated that the seismic hazard analysis by Tetra Tech (2010) evaluated the PGA for
long-term site conditions. Tetra Tech conducted a deterministic seismic hazard analysis and
compared the results with the PGA associated with a 2 percent probability of exceedance during
a 200-year design life, based on the USGS 2008 National Seismic Hazard Mapping Program
(NSHMP) PSHA Interactive Deaggregation data. Two percent probability of exceedance during
a 200-year period is equivalent to a return period of9,900 years. The U.S. Environmental
Protection Agency (EPA) Standards for the Control of Residual Radioactive Materials from
Inactive Uranium Processing Sites (40 CFR 192) and the NRC Criteria Relating to the
Operation of Uranium Mills and the Disposition of Tailings or Wastes Produced by the
Extraction or Concentration of Source Material From Ores Processed Primarily for Their
Source Material Content (NRC 10 CFR Appendix A to Part 100 A) both specify that control of
residual radioactive material must be effective for up to 1,000 years to the extent reasonably
achievable, and for at least 200 years. Use of a 9,900-year return period in formulating the
probabilistic design criteria for reclaimed conditions is considered conservative as this event has
a 2 percent probability of exceedance during a 200-year period and a less than 10 percent
probability of exceedance in a 1,000-year period.
In May 2012, EFR submitted a technical memorandum which EFR indicated represents a site-
specific probabilistic seismic hazard analysis (PSHA) for both operational conditions and long-
term reclaimed conditions for the site. This analysis was provided as Attachment A to Denison
2012a
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TECHNICAL MEMORANDUM
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EFR indicated that the site Vs30 was calculated by Tetra Tech (2010) for the uppermost 100 feet
of soil and bedrock underlying the site. The site-specific Vs30 was determined to be 586 m/s.
This seismic velocity correlates to materials characterized as Site Class E - Soft Soil by both the
International Building Code (IBC) and the National Earthquake Hazard Reduction Program
(NEHRP).
MWH Americas, Inc. (MWH), on behalf of Denison, checked Tetra Tech's calculation ofVs for
the uppermost 100 feet of soils and bedrock underlying the site. The drilling logs by Tetra Tech
(2010) and Dames and Moore (1978) were used to obtain information about the subsurface
conditions at the site (Standard Penetration Test (SPT) blow counts, bedrock descriptions, and
depths of auger drilling versus coring) and to calculate values of Vs for the soils and estimate
values ofVs30 for the underlying bedrock materials.
EFR stated that the average value of SPT blow counts for the silty sand and soil material
encountered in the top 30 feet of the Tetra Tech boring is 58.6 (Tetra Tech 2010). Using
information in Sykora (1987) (eqs.20, 21 and Table 4 eq. 8) values ofVs30 were calculated to
range from approximately 660feet/second (ft/s) to 990ft/s (approximately 200 to 300
meters/second (m/s)). This is also consistent with information presented in Fig. 5, Fig. 6, Fig. 10,
and Table 8 of Sykora (1987). Based on the bedrock descriptions presented in the drilling logs
by Dames and Moore (1978) to a maximum depth of 140 feel the estimated seismic velocity for
the remaining 70 feet of generally well-cemented sandstone with minor interbedded claystone,
siltstone and conglomerate, is estimated to range from 800 to 1,000 m/s. A weighted average of
seismic velocity for the upper 100 feet below the site was calculated to range from approximately
620 m/s to 700 m/s. This seismic velocity correlates with materials characterized as Site Class D
^ Stiff Soil by both the IBC and NEHRP.
EFR indicated that the NSHMP 2008 PSHA Interactive Deaggregation web site used by Tetra
Tech to calculate the PGA for the site limits input values ofVs30 to either 760 m/s or 2,000 m/s.
These seismic velocities correspond to Site Class BC (intermediate between dense soil and rock)
and Site Class A (hard rock), respectively. Although the text that accompanies the PSHA
program states that site-specific values ofVs30 can be input for sites in the Western US, the
White Mesa site is considered to be located within the Central/Eastern United States for the
program (Martinez 2012), and input values for Vs30 are limited to 760 m/s or 2,000 m/s. The
available input value ofVs30 of 760 m/s is appropriate for the site-specific analysis based on the
range of seismic velocity estimated for the site.
EFR also indicated that evaluation of the PGA due to a background earthquake unassociated
with a known structure is typically included as a portion of a deterministic seismic hazard
analysis. The analysis includes evaluating the potential for low to moderate earthquakes
unassociated with tectonic structures to contribute to the seismic hazard of the site. The seismic
hazard analysis performed by Tetra Tech included an evaluation of a background earthquake
because it was a deterministic analysis. However, in order to evaluate the contribution from a
background event in a deterministic analysis, one must estimate a likely magnitude and distance
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
from the site. Tetra Tech (2010) estimated a magnitude 6.3 event consistent with that used in
previous seismic evaluations performed for sites in the Colorado plateau, and cited in their
report. The 15km distance to a background earthquake was chosen as a distance which would
provide a conservative PGA at the site.
EFR stated that the total seismic hazard at a site is better quantified by performing a
probabilistic seismic hazard analysis to determine the likelihood of a specific ground
acceleration occurring at the site within a given timeframe (operational or reclaimed design
life). EFR referred to the May 2012 probabilistic seismic hazard analysis for additional details.
EFR indicated that the site-specific PSHA for the Site determined that the PGA associated with a
2 percent probability of exceedance in 50 years, calculated for the operational lifetime of the
facility, is 0.07g. The PGA associated with a 2 percent probability of exceedance in 200 years,
calculated for the long-term reclaimed site conditions, is 0.15g. The details of the analysis are
presented in Attachment A of the previous response document (Denison 2012a).
5.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan 5.0 R313-24-4; 10CFR40, Appendix A; INT 05/1; Seismic Hazard
Evaluation
Results of the Division's review of EFR's Response to each individual interrogatory
statement in this Round 1 interrogatory are summarized below.
As stated in the Basis for the Interrogatory and Round 1 Interrogatory statement #5, "The
USGS National Hazard Maps should not be used for developing site-specific seismic design
parameters (personal communication between Dr. Mark Petersen, Chief, National Seismic
Hazard Mapping Project and Ivan Wong of URS Corporation, 2010) for critical and
important facilities. For such fypes of facilities, a site-specific probabilistic seismic hazard
analysis (PSHA) is recommended." However, contrary to this recommendation, Denison's
consultant MWH in response used the USGS National Hazard Maps (specifically the
interactive deaggregation tool) to recommend design ground motions for the facilify. EFR
did not perform a site-specific PSHA as requested. Use of the National Hazard Maps does
not constitute a site-specific PSHA. The maps are four years old and are in the process of
being updated. PSHA computer software such as EZFRISK® are readily available to
perform a site-specific PSHA. Below are specific comments on EFR's responses to the
interrogatory statements:
1. Please further clarify the rationale for selecting the annual probabilify of
exceedance of hazard for the facilify.
EFR has adequately responded to this statement.
2. Adjust the cited USGS National Hazard Map PGA value of 0.15 g for the site Vs30
as appropriate.
EFR states that the site-specific Vs30 (time-averaged shear-wave velocify in the top
30 m) as determined by Tetra Tech (2010) was 586 m/sec corresponding to a
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
NEHRP site class E or soft soil. This is an erroneous statement. A Vs30 of 586 m/sec
actually corresponds to a NEHRP site class C, very dense soil or soft rock. MWH
also estimated the Vs30 for the site and concluded that the Vs30 ranged from 620 to
700 m/sec corresponding to a NEHRP site class D or stiff soil. This is also incorrect.
This range in Vs30 also corresponds to a NEHRP site class C. Aside from these
errors, the shear-wave velocify (Vs) estimate for the 10 m of soil appears reasonable
although SPT does not measure Vs directly and so the uncertainties in the inferred
Vs can be significant. However the technical basis for the Vs for the remaining 20 m
of interbedded sandstone needs to be provided.
As stated above and in Statement 5, a request had been made not to use the National
Hazard Maps but to perform a site-specific seismic hazard evaluation. The
assumption that a site Vs30 of 760 m/sec is appropriate for the site allowing use of
the maps is problematic.
More importantly, the characterization ofthe site as a thin soil site where there is 10
m of soil over firm (?) rock (Tetra Tech, 2010) indicates that a site response analysis
is now required to address site effects on ground motions. The sharp Vs contrast
between the lower velocify soil and the higher velocify rock will amplify short-
period ground motions like PGA by as much as a factor of 2 for low rock ground
motion inputs. The use of Vs30 in a site-specific hazard analysis will not capture
these site amplification effects (Abrahamson, 2011). A site response analysis with a
Vs profile into the rock should be performed. Using an equivalent-linear or fully
non-linear computer code would be acceptable. It is recommended that direct
measurements of Vs be made for input into the site response analysis.
3. Explain why the calculated hazard for the background earthquake PGA of 0.24 g
was estimated but ignored in the recommendation provided in Appendix E.
EFR did not respond to this statement. However that question is now irrelevant
because of the following actions. As recommended and agreed to by Denison in
Response 3, a site-specific PSHA is the best approach for quantifying the hazard at
^ the site particularly from background earthquakes. Denison states that was done as
in discussed in Response 5 and as contained in Attachment A. A site-specific PSHA
was in fact not performed but the National Hazard Maps were used as stated above
and below.
4. Provide information to justify the use of 15 km distance for a background
earthquake Mw 6.3 event.
EFR's response referred back to Response 3. EFR stated that the 15 km distance
was selected because it would provide a conservative PGA at the site. This response
fails to answer the question. A distance of 10 km would also provide a "conservative
PGA at the site". However, this is now an irrelevant question because a
deterministic seismic hazard analysis is to be replaced by a site-specific PSHA
although such an analysis has yet to be performed.
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
5. Perform and report results of a site-specific PSHA in lieu of using the USGS
National Hazard Maps for developing site-specific seismic design parameters.
As commented above, a site-specific PSHA was not done and the 2008 USGS
National Hazard Maps were used. The USGS National Hazard Maps consider the
Colorado Plateau in which the site is located as part of the central and eastern U.S.
with respect to ground motion prediction models. Denison's Attachment 5 shows
those ground motion models. Recent research by the USGS (McNam'ara et al. 2012)
and studies for the proposed Blue Castle nuclear power plant site near Green River
(Jennie Watson, personal communication, Dec 2012) indicate that is an erroneous
assumption and that the use of western U.S. ground motion prediction models is
more appropriate. Early site-specific PSHAs including an analysis for the NRC-
regulated Atlas iVloab tailings site (Wong et al. 1996) and the U.S. Bureau of
Reclamation's Glen Canyon Dam (URS 1999) used western U.S. ground motion
models. This is another reason why the National Hazard Maps should not be used
for developing site-specific design parameters. It is strongly recommended that the
Next Generation of Attenuation (NGA) ground motion prediction models be used in
the site-specific PSHA for White Mesa. It is expected that the USGS will use the
NGA models for the Colorado Plateau in the 2013 National Hazard Maps.
6.0 Slope Stability
6.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4; 10CFR40,
Appendix A, Criterion 1; INT 06/1; Slope Stability
The interrogatory requested that EFR do the following:
1. Demonstrate slope stability for the tailings impoundment and new cover system using
shear strength parameters and other soil properties assigned to the various components
(cover, embankment/dike, tailings, and foundation) consistent with soil type, degree of
compaction, and anticipated degree of variability. Justify selection of values for soil
parameters.
2. In evaluating slope stability, address and report the effects of shallow and non-circular
failure surfaces, in addition to circular and/or deeper ones.
3. Demonstrate that assumed drainage conditions are appropriate, are at least consistent
with, or are conservative compared with drainage/seepage results, projected immediately
at closure and at the end of the impoundment design life (i.e., 1,000 years, to the extent
reasonably achievable, and, in any case, for at least 200 years).
4. Assess the slope stability of Cell 1 adjacent to Cell 2 where mill debris and contaminated
soils are to be placed and covered.
5. Explain and justify the selection of the pseudo-static coefficient used in the assessment of
seismic stability. If the selected value of the pseudo-static coefficient cannot be justified,
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
revise the value of the coefficient used in stability analyses and revise and report the
results of stability analyses.
6.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24-4;
10CFR40, Appendix A, Criterion 1; INT 06/1; Slope Stability
IN ITS RESPONSE, EFR provided a revised slope stability analysis (Attachment D ofthe
Response, to be included in the future Appendix E, Slope Stability Analysis, ofthe Updated
Tailings Cover Design Report (Appendix D to the revised Reclamation Plan).
IN ITS RESPONSE, EFR also indicated the following:
• The revised stability analyses include evaluation of shallow and non-circular failures;
• The phreatic conditions used for the revised stability analyses are consistent with regards
to the tailings dewatering analyses;
• The revised stability analyses include evaluation of the stability ofthe Celll Disposal
Area embankment; and
• An update to the previous seismic study for the site has been conducted and was included
as Attachment A of the previous response submittal (Denison, 2012a). The pseudo-static
coefficient is estimated as 0.10 corresponding to 2/3 of the Peak Ground Acceleration
(PGA) presented in the Attachment A of Denison (2012a). This pseudostatic coefficient
was used for the revised slope stability analyses.
6.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev 5.0 R313-24-4; 10CFR40, Appendix A, Criterion 1; INT 06/1; Slope
Stability
The Division finds that the revised slope stability analysis provided in the revised
Attachment D to the EFR response did not adequately address several considerations and
criteria that may be important to the analysis of the stability of the closed tailings
embankment, including the following:
• No details were provided regarding shear strength data for the liner and LCRS
components in Cells 4A and 4B
• No information was provided as how the bottom liner component(s) was (were)
simulated in the global stability analysis completed for cross Section A through Cell 4B
• No details were provided regarding shear strength data for the liner and LCRS
components in Cell 2
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
• No information was provided as how the bottom liner component(s) was (were)
simulated in the global stability analysis completed for cross Section B through Cells 2
and 1
• Insufficient information was provided regarding:
1) the estimated in-place dry density, in-place most density, and in-place saturated
density (unit weight values) ofthe tailings;
2) rationale for selecting the tailings condition and tailings properties assumed in
the analysis (e.g., drained vs. undrained conditions and for selection of in-place
moist tailings density vs. in-place saturated tailings density for long-term static
conditions or long-term seismic conditions); and
3) the location of the assumed water table, e.g., if drained condition assumed;
• The discussion and Table E.l in Attachment D of table of the material properties used
in the model did not distinguish between different material strength parameters
assumed for long-term static conditions vs. long-term seismic conditions, e.g., no
discussion of percentage reduction in strength properties for the seismic (pseudostatic)
stability analysis was provided;
• No discussion of or rationale was provided for whether it may be appropriate and
reasonably conservative to assume that the tailings dewatering system might be clogged,
possibly leading to ineffective drainage at the base of the tailings cell in area including
the lowest point in the tailings bottom surface and therefore possibly result in an
undrained condition within the tailings. For such a case, undrained tailings strength
relationships might suggest strength values for the tailings that may be different than
those assumed by EFR; and
• No discussion or rationale was provided for whether it may be appropriate and
reasonably conservative to assume that the strength parameters for the clay liner in the
Cell 1 area might be estimated based on the PI that would lead to the weakest strength,
or estimated using some other method that would generate the weakest estimated shear
strength value for the clay liner.
The Division requests that EFR, in Attachment D, further define how the tailings total unit
weight value stated in Table E.l (90 pcf) and used in the revised slope stability analysis was
derived (or how representative a value that value is of the tailings). For example, tailings
sample results (see Appendix F, Settlement and Liquefaction Analyses 6f Updated Tailings
Cover Design Report, Denison 2011) indicate that the tailings have an avierage specific
gravity of 2.73; if a dry unit weight of 90 pcf were assumed (Section E.3 of Attachment D of
this Response,) an average tailings void ratio of about 0.89 would result. Based on this void
ratio, the tailings bulk density would be approximately 119.4 pcf, compared to the total
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
unit weight of the tailings listed in Table E.l of Attachment D of this Response of 95 pcf.
Alternatively, if an average tailings dry unit weight of 86.3 pcf were assumed (as was done
in Appendix F, Settlement and Liquefaction Analyses of the Updated Tailings Cover
Design Report, Denison 2011), then an average tailings void ratio of about 0.97 would
result. Based on this void ratio, the tailings bulk density would be approximately 117.2 pcf.
EFR should reevaluate and verify that their assumed tailings properties, calculation
methodologies, and assumptions are representative, reasonably conservative, and
bounding.
7.0 Settlement and Potential for Cover Slope Reversal and/or Cover Layer
Cracking
7.1 Round 1 Interrogatory White Mesa RecPlan.5.0 R313-24-4; 10CFR40, Appendix Aj
Criterion 4; INT 07/1; Technical Analvsis - Settlement and Potential for Cover
Slope Reversal and/or Cover Laver Cracking
The interrogatory requested that EFR do the following:
Refer to Appendix D, Updated Tailings Cover Design Report of the Reclamation Plan, Rev. 5,
and Drawings TRC-1 through TRC-8 in the Reclamation Plan, Rev. 5.0:
1. Please revise (i.e., steepen) the slopes of the top slope portions of the fmal cover system to
provide an adequate factor of safety to ensure long-term stability of the covered embankment
area considering:
a. The potential for future slope reversal(s) and/or cracking to occur in the cover system
due to long-term total and differential settlement or subsidence which could lead to
conditions where ponding of precipitation could occur on the cover system in the
future, after the end of the active institutional control period; and
b. The significant disparity between the presently proposed topslope inclination ranges
and published recommended ranges of slopes for finaf cover systems for uranium mill
tailings repositories, surface impoundments, and landfills - namely ranging between
2% to 5% (e.g., see DOE 1989; EPA 1989; EPA 1991, and ITRC 2003 and EPA
2004).
OR, altematively, provide additional evaluations that clearly and unequivocally demonstrate
(1) the ability to constmct such gently sloped cover systems as proposed, designed, and
specified and (2) the ability of the proposed embankment closure cover design to
accommodate settlement-induced slope changes (including slope reversal) without increasing
infiltration into the stabilized tailings impoundment.
2. Provide technical justification for 1) quantitative acceptance criteria to be used as the basis
for evaluating the potential for slope reversal within the cover system in terms of potential
long-term total and differential settlement, 2) quantitative assessments of maximum tensile
strain capacity and other engineering properties such as Atterberg limits ofthe materials to be
used in design of the cover system, and 3) quantitative acceptance criteria, including
maximum allowable linear and angular distortion values, including effects of bending within
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
any select layer or layers of the cover, and (4) the minimum acceptable factor of safety for
concluding that cover layer cracking will not occur.
3. Provide engineering analyses (including calculations and numerical modeling simulations as
applicable) documenting the range of anticipated total and differential settlements within
each of the containment cells. In doing so, use consolidation parameters obtained from site-
specific testing of the tailings materials, reflecting both spatial and temporal variations in the
tailings. Data from other sources may supplement (but not replace) site-specific test data in
the analyses.
4. Demonstrate that tailings have been deposited in such a way that variations in tailings
properties by location do not compromise the stability of the tailings as a foundation for
cover system constmction. Consider effects of sand-rich tailings zones lying adjacent to our
near slime-rich tailings zones, due to deposition during slurry flow. Describe and account for
effects of any different tailings placement methods (e.g., wet slurry vs. thickened slurry
deposition) used throughout the mill's operating life. Identify and quantify the effects on
stability of variations in such tailings physical characteristics as moisture content,
consolidation coefficients, specific gravity, hydraulic conductivity (as listed in Appendix D
Updated Tailings Cover Design Report, September 2011). Perform and provide results of
numerical analyses using this information to project differential settlement across the tailings
impoundments using software such as the Fast Lagrangian Analysis of Continuum (FLAG®)
code (Itasca 2009) or other similar software, as appropriate. Altematively, provide
information to justify why such analyses are not warranted.
5. Include secondary settlement (i.e., creep) and any seismically induced settlement ofthe
tailings in settlement analyses and consider their effects when assessing the anticipated
performance of the cover system.
6. Demonstrate that the results of settlement analyses are consistent with results of
drainage/dewatering analyses. Ensure that drainage/dewatering analyses reflect the tailings
and drainage conditions (including slime drain system) existing in each cell.
7. Perform and report results of sensitivity and uncertainty analyses to demonstrate that the
cover system will remain stable despite the effects of differential settlement. Report the time
required to reach 90% consolidation.
8. As part of the analyses identified above, please also perform a seepage analyses to evaluate
the shape of the phreatic surface within the tailings prism for each representative area within
Cells 2 and/or 3, 4A, and 4B to be analyzed for consolidation timeframes and in differential
settlement analyses. Ensure that effects of planned dewatering procedures and the dewatering
system design configuration in each specific cell analyzed are reflected in seepage analyses.
9. Provide sensitivity analyses to assess the effect a of changes in tailings coefficients of
consolidation parameters, void ratios, and tailings hydraulic conductivity values (note: it is
acknowledged that values of all of these parameters are subject to uncertainty) on the amount
of time required to reach approximately 90% consolidation of the tailings at each locations
assessed within each cell and/or across individual tailings cells.
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TECHNICAL MEMORANDUM
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10. Using the information obtained from the analyses identified above, for each critical section
defined, complete differential settlement analyses and compare the analyses results to the
specified design criteria and evaluate the potential for slope reversal(s) to occur in the cover
system over the tailings cells over the worst-case sections analyzed.
11. Provide information on the expected range of plasticity characteristics of the soil materials
proposed for use for constmcting the highly compacted upper portion ofthe radon
attenuation and radon attenuation and grading layer of the proposed cover system, and
specify design criteria (including maximum allowable values of both linear and angular
distortion) to be used for evaluating the potential for cracking of this layer to occur as a result
of any differential settlement that may occur.
7.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan_5.0 R313-24-4;
10CFR40, Appendix Aa^Criterion 4; INT 07/1; Technical Analysis - Settlement and
Potential for Cover Slope Reversal and/or Cover Laver Cracking
IN ITS RESPONSE, EFR provided a list of eight reclaimed uranium mill tailings repositories in
the US. where either cover slopes or portions of cover slopes have been constructed at^
inclinations of less than 1 %.
IN ITS RESPONSE, EFR also did the following:
1) Conducted a revised settlement analysis to update the analysis that was completed for
Rev. 5.0 of the Reclamation Plan in 2011 (Denison 2011)
2) Provided additional discussion of the results of that analysis (provided as part of this
Response)
3) Conducted a cover cracking analysis for the highly compacted cover layer (provided as
part of this Response).
IN ITS RESPONSE, EFR further indicated the following:
• No site-specific testing of tailings is proposed to be performed;
• Knowledge of tailings discharge history with observation of the response of tailings to
interim cover placement (le. settlement monitoring) provide the most reliable
information for identifying the potential for, and location of slimes or other soft zones.
Interim cover has been placed over the tailings in Cell 2 and the portions of Cell 3. The
results for Cell 2 are considered representative of the conditions that would he expected
for Cell 3 and Cells 4A and 4B;
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TECHNICAL MEMORANDUM .
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
• The one-dimensional consolidation analyses are seen as providing a realistic estimate of
total amount of primary consolidation settlement due to dewatering;
• Sufficient information was provided in the dewatering analyses to estimate the rate at
which consolidation settlement will occur during dewatering. Supplemental seepage
analyses were not performed for the settlement analyses. The actual rates and amounts of
settlement occurring during the dewatering phase will continue to be monitored as
dewatering progresses to provide verification of the estimated settlements at each
monitoring location; and
• Sensitivity analyses to variations in the rate parameters (as reflected in settlement
monitoring results) were performed for the 90 percent consolidation calculations and the
range of values are provided in Response 2 for Cell 2. The results for Cell 2 are
considered representative of the conditions that would be expected for Cell 3 and Cells
4Aand4B.
7.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0; R313-24-4; 10CFR40, Appendix A, Criterion 4; INT 07/1;
Technical Analvsis - Settlement and Potential for Cover Slope Reversal and/or
Cover Layer Cracking
As discussed in the Response to Interrogatory No. 3 in Section 3.0 above, EFR did not
provide settlement performance data or settlement prediction analyses for any of the other
facilities referenced by EFR as having been constructed with a similar range of topslope
inclinations. Similarly, EFR did not provide any information demonstrating a correlation
between observed settlement at these repositories and the future settlement predictions
developed for those facilities that might allow the performance of these facilities to be
evaluated with respect to their observed or predicted post-construction behavior.
The revised settlement analysis included one-dimensional analyses of both primary
consolidation and estimates of settlement due to creep associated with secondary
consolidation occurring during (i) interim soil cover placement/loading; (ii) tailings
dewatering; and (iii) final cover loading. EFR also provided estimates of seismically-
induced settlement due to earthquake loading.
In its settlement analyses, EFR relies of data from settlement monuments in Cell 2 to
estimate settlement parameters (e.g., compression indices and coefficients of consolidation)
for the tailings. Each monument or monitoring point is treated independently, and the
range of data and corresponding analytical results are reported in terms of maximum,
minimum and average values. Examination of the data indicates that the 5 westernmost
monuments or monitoring locations (2W12W2,2W3,2W3-S, and 2W4) behave very
differently than the others, with an average observed settlement of about 0.77 feet from
July 1991 (on average) to the start of dewatering in 2009, whereas the other data set only
averages about 0.1 feet during a period most typically from July 2005 to January 2009.
Given the grossly different amounts of settlement between the two sets of settlement data
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
(and the issue not simply being a matter of greater tailings thickness), the use of a simple
average across the two sets of data seems inappropriate. More importantly, given the
relatively short time of settlement observation for the eastern monuments and the flat
shape of the settlement curves, it seems likely that signiflcant settlement occurred prior to
monitoring, thus making this approach to settlement estimation problematic as was
discussed in the first Interrogatory. If significant portions of the settlement time histories
were not captured in the eastern monitoring data, the use of "average" values derived from
the data (as apparently is the case currently) will hot represent the behavior a majority of
tailings under newly added load. On the other hand, if the range of settlement data as
measured is representative of true settlement behavior, then a significant range of possible
behavior should be expected (reflective of directive in the first round of interrogatories to
consider a range of tailings ranging from fine grained slimes to coarse sands and their
spatial distribution within the impoundment cells).
EFR has attempted estimate both compression indices and coefficients of consolidation for
the tailing by curve fitting settlement data from five of the monitoring points (those
possessing enough curvature to which a curve can be fit) with theoretical settlement curves.
From the plots provided in Attachment E, it appears that something is amiss in the curve-
fitting analyses since primary and secondary consolidation appears to be happening at the
same time, rather than secondary occurring after completion of primary. Such an error
would make the "back-calculated" indices and coefficients incorrect. This issue should be
examined further. Again, as stated in the first round of Interrogatories, this back-
calculation or curve-fitting approach is problematic at since the start of the settlement time
history prior to monitoring is missing and a third variable (the effective drainage length) is
not precisely known. Because of this, variance from calculated values should be expected
and must be considered when evaluating subsequent cover performance. To better address
the shortcomings inherent in using this curve-fitting/back-calculation approach, it was
stated in the previous Interrogatory to "use consolidation parameters obtained from site-
specific testing of the tailings materials, reflecting both spatial and temporal variations in
the tailings."
The settlement analyses performed by EFR focused on evaluating settlement in the Cell 2
area only. No discussion or analyses were provided regarding any tailings
management/disposal process-related differences such as different tailings placement
methods/modes that may have occurred/might exist with regard to the various tailings
disposal cells or of the effects that such differences might have on tailings consolidation and
settlement behavior in each disposal cell area. Additionally, no discussion or analyses were
provided for differences in dewatering system designs, differences in the expected
dewatering efficiencies likely to occur between different cells (with resulting differences in
statured tailings thicknesses at the different stages in time evaluated in the settlement
analyses), or differences in thicknesses of tailings in the different cells (e.g., tailings
thickness in Cell 4A varies from about 26 to 42 ft, with an average thickness of about 34 ft,
vs. tailings thickness ranging from about 14.5 ft to 28.50 ft in Cell 2).
In the Response to Item 2. of this Rd 1 interrogatory, EFR indicated that a final water level
in the tailings in Cell 2 at the end of dewatering was estimated based on dewatering
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TECHNICAL MEMORANDUM
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analyses presented in the Revised ICTM Report. However, the Reclamation does not
contain a schedule for, a detailed description of, measures that EFR will undertake to
ensure that dewatering of Cells 2 and 3 will be completed within the 7-year time period
specified in the latest Financial Surety submitted to the Division by EFR, or a shorter time
period. This is important since recent data suggests that the current rate of dewatering in
Cell 2 may be on the order of 1 inch per year. As part of the additional settlement analyses
that are needed to further address differential settlement and evaluate impacts of
differential settlement on cover slope integrity/slope reversal, EFR needs to address
additional requirements related to dewatering analyses, measures, costs, and schedule for
dewatering of Cells 2 and 3 as described in Section 15.3 below.
In calculating the settlement ofthe tailings in Cell 2, it appears that tailings above elevation
,5604.95 (a datum which seems to correspond to the average 2009 first quarter water levels
plus an assumed 3-foot perched zone thickness) have been omitted from consideration
during future dewatering and placement ofthe final cover (from time tl to t2, and from t2
to t3). Even above the water table, these materials will respond to the added stresses from
cover construction and their contribution to total settlement should be included.
Neither the response nor Attachment E presents a rationale for selecting tailings properties
(e.g., specific gravity of tailings of 2.75, moist unit weight of 100.29 pcf above the capillary
fringe, long-term moisture content of 16.2%, void ratio of 0.99 assumed for the Phase 1
analysis) to be used in the revised settlement analyses. Further, while unit weights for the'
various components of the cover system have been provided, their thickness have not all be
provided, thus preventing a check of the stresses resulting from cover placement. The
thickness of each component of the cover system needs to be indicated in the calculation
spreadsheet.
Without a narrative and sample calculations for all of the spreadsheet results presented in
Attachment E, it is difficult to assess the adequacy of the analysis presented. For example,
it is unclear how the bottom elevation of the "upper zone" was determined, and then how
the thicknesses of the upper and lower zones correspond to the drainage path used to
determine the time for 90% consolidation. Such clarification need to be provided in order
to assess the adequacy of the settlement calculations. General references to calculation
methodology such as "Terzaghi et al. 1996, pages 223-240" are too general to satisfy this
need for additional information.
It is unclear what time for primary consolidation was used in calculating the secondary
settlement, and the reviewer is otherwise unable to assess the results calculated by EFR.
Again, a narrative and/or sample calculations (or at least illustrative equations and a
description of how specific values were determined) should be provided for all spreadsheet
calculations in order to assess their correctness.
With respect to the calculated seismically induced settlement, there appears to be errors in
the calculation process (for example, the vertical strain should be twice the resultant of the
vertical strain for 15 cycles of shaking multiplied by the variable Cn [doubling is to account
for the multi-directional application of strain as described in the referenced Stewart and
Whang (2003) paper]). Also, the calculations incorrectly treat the tailings as a single layer
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TECHNICAL MEMORANDUM
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subject to a constant amount of cyclic strain. The tailings should be discretized into
smaller, discrete layers and the stress and strain calculations redone. Another apparent
inaccuracy in EFR's calculation is an apparent capping of shear strain amplitude to 1.0%.
In Stewart and Whang's cyclic strain charts (Fig 3 in their paper), cyclic shear strain
values are shown up to 1%, which is a reasonable limit for compacted soils (noting that
"compacted soils" is part of the title of Stewart and Whang's paper). However, the soils in
question are uncompacted tailings in which cyclic strains could exceed 1%. Hence,
extrapolation or another calculation methodology should be used to determine seismically
induced settlement. Also, the Stewart and Whang procedure is not well established (vetted)
within the geotechnical earthquake engineering communify^ Consequently, EFR should
compare the results obtained using this procedure with those of a more-well established
procedure such as Tokimatsu and Seed (1987) or Ishihara and Yoshimine (1992).
In reviewing Table 2 'Summary of Settlement Results', it is unclear how the values shown
for "Total Settlement five years after placement of Final Cover due to Final Cover
Placement, Creep, and a Seismic Event" in row 5 (minimum and maximum values of 0.52
to 0.83) were determined. While calculations supporting the preceding four rows of
settlement results in the table are readily identified within the spreadsheet calculations
presented in Attachment E, no explicit calculations justifying the fifth row of values are
presented. Additional information is needed.
In its assessment of differential settlement and cover cracking analysis, ERF estimates that
the "maximum potential differential settlement that could be expected between adjacent
movement monitoring locations would be on the order of 0.3 feet." With fypical spacings
between monitoring locations of about 250 feet (scaled from the figure by the reviewer, and
an explicit statement of such should be provided by EFR), this equates to an average
deflection ratio (differential settlement) of about 0.12%, which is less than the proposed
minimum cover slope of 0.5%, and hence on this basis, ponding is not expected. However,
the value of 0.3 feet needs to be reassessed due to the issues just previously presented.
In assessing the potential cracking of the cover, EFR has relied upon the most critical
combination of projected settlement of a monitoring point (0.9 ft at 2W4-S) and it
associated distance away from the edge of the tailings cell (being for this monument 100 ft)
to determine the greatest strain demand on the cover based on the approach of Lee and
Shen (1969). This value is then compared to the cracking resistance based on an empirical
relationship using soil index properties (Claire et al. of Morrison-Knudsen, 1993). While
this approach is reasonable, the input for Lee and Shen's horizontal movement formula
has been incorrectly selected. In the analysis, EFR has used the average slope of the
settlement profile (0.9/100) rather than a local maximum which would include the effects of
bending. This point is illustrated in the test data and illustrative example provided in Lee
and Shen's paper: the vertical displacement between the two ends of their 93-inch long soil
beam is 1 inch, yielding an average slope of about 1%; however, the maximum slope in
their beam which includes bending is 2%, located near the middle of the beam. In Lee and
Shen's paper, the maximum reported tensile horizontal strain is about 0.6%, derived from
the 2% maximum (not 1% average overall) slope. To be consistent with Lee and Shen, EFR
should use the expected peak slope between points, not the average between the two points.
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TECHNICAL MEMORANDUM
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Assuming that the peak is twice the average as in Lee and Shen's test case (although ERF
will need to provide a reasoned and defensible value specific to this project; representative
published relationships depicting cover deformation shapes and tensile strain/distortion
relationships include those included in Gourc et al. (2010) and Rajesh and Viswanadham
(2010), the maximum horizontal strain appears to be twice that of the 0.028% previously
reported, exceeding the reported maximum allowable strain of 0.05%, meaning that the
layer is expected crack. The analysis must be redone to include the effects of localized
bending as was indicated in the first round of Interrogatories, and the performance of the
cover reassessed accordingly.
Also relating to the cracking analysis, a thickness of 4.7 ft is used for the soil layer.
However, the actual thickness of the sandy clayey silt soils in the tailings cover design,
which collectively serve for radon attenuation is 8.8 ft per Figure 2-2 of the Revised ICTM
Report (Denison Mines 2010). The analysis should either be revised to reflect this value or a
justification provided for the value used.
As part of the previous Interrogatory, EFR was asked to "demonstrate that the results of
settlement analyses are consistent with results of drainage/dewatering analyses, and ensure
that drainage/dewatering analyses reflect the tailings and drainage conditions (including
slime drain system) existing in each cell. In EFR's Response, the following statement is
made:
"It should be noted the assumptions made in the one-dimensional consolidation analyses of
Phase 2 (i.e. complete coverage of the tailings impoundment by an infinitely-permeable
underdrain system, and instantaneous drawdown to final water level) do not exist within
the impoundment, and will result in an underestimation of the time required to achieve
90% consolidation. The results of the tailings dewatering analysis, which includes the 3-
dimensional aspects of flow toward the underdrain strips, and a finite underdrain
permeabilify, are considered to provide a more reliable estimate of the duration Phase 2
consolidation."
Unfortunately, no further reference or discussion is presented regarding the dewatering
analyses, and hence the question of time needed to reach 90% consolidation remains
unresolved. Based on its consolidation settlement analysis, EFR reports that the time to
reach 90 percent of primary consolidation due to dewatering ofthe tailings in Cell 2 ranges
from 0.14 to 0.63 years. However, in the dewatering analysis (see Appendix J of Revised
Infiltration and Contaminant Transport Modeling Report, White Mesa Mill Site, Blanding,
Utah, by MWA 2010)), EFR reports that "the MODFLOW dewatering model predicts that
the tailings would drain down nonlinearly through time reaching an average saturated
thickness of 3.5 feet (1.07 m) after 10 years of dewatering." These two conclusions are not
compatible. As part of this Response to Interrogatory, the results of the dewatering
analyses need to be considered in conjunction with the settlement analyses and the
subsequent assessment of cover settlement.
As stated previously, no explicit discussion or analyses were provided regarding any
tailings management/disposal process-related differences such as different tailings
placement methods/modes that may have occurred/might exist with regard to the various
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TECHNICAL MEMORANDUM
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tailings disposal cells or of the effects that such differences might have on tailings
consolidation and settlement behavior in each disposal cell area. Additionally, no discussion
or analyses were provided for differences in dewatering system designs, differences in the
expected dewatering efficiencies likely to occur between different cells (with resulting
differences in statured tailings thicknesses at the different stages in time evaluated in the
settlement analyses), or differences in thicknesses of tailings in the different cells.
In summary, based on review of all of the above, the Division concludes that the analyses
provided by EFR are, in general, overly simplistic and do not adequately account for the
full range of different conditions that may occur with the tailings management cells area.
Extrapolating assumed tailings parameters and properties from published data on tailings
at other facilities creates additional uncertainties in the consolidation, settlement, stabilify,
and liquefaction analyses. Assumed data must be supplemented by site-specific data;
alternatively, the most reasonably conservative values might be used if adequate
assessment and justification is provided. Justifications for some parameter values are
lacking in EFR's response. EFR should provide additional analyses that specifically
address the different factors and conditions and their effects referenced in the preceding
paragraphs. Also, there appears to be several errors, omissions, discrepancies, and
insufficient information in the analyses conducted and provided by EFR which need to be
to be addressed before appropriate and reliable conclusions can be reached.
8.0 Erosion Stability Evaluation
8.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; 10CFR40,
Appendix A, Criterion 4; INT 08/1; Technical Analysis - Erosion Stability
Evaluation
The interrogatory requested that EFR do the following:
Refer to Section 3.3.5 of the Reclamation Plan, Rev. 5.0 and Section 4.9 and Appendix G to
Appendix D (Updated Tailings Cover Design Report), and Drawings TRC-1 through TRC-8
to the Reclamation Plan, Rev. 5.0: Please provide the following:
1. To further confirm the appropriateness and currency of the calculated Probable
Maximum Precipitation (PMP) value and as used, for example, in the ET cover design
erosion protection rock rip rap sizing calculations, please provide a revised PMP
calculation updating the PMP distribution that incorporates information from the
following documents, in addition to HMR 49 (Hansen et al.l984):
• "2002 Update for Probable Maximum Precipitation, Utah 72 Hour Estimates to
5,000 sq. mi". - March 2003 Jensen 2003); and
• "Probable Maximum Precipitation Estimates for Short Duration, Small Area
Storms in Utah" - October 1995 (Jensen 1995)
2. Using the revised PMP information obtained from Item 1 above, provide revised
calculations of required rock rip rap sizes for the cover sideslope areas using the updated
method developed for round-shaped rip rap as described in Abt et al. 2008. Update and
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
revise other erosion protection calculation presented in Appendix G, as required and
appropriate, to reflect the revised PMP determination.
3. Please provide additional calculations to estimate the magnitude and location of a
potential gully intmsion into each soil-covered portion of the proposed cover system
(e.g., using the procedure described in Thomton and Abt 2008). Demonstrate that
excluding rock (gravel) particles from the currently proposed flattest (0.1 % and 0.5%)
top slope areas would adequately protect against sheet flow under potential precipitation
conditions and would adequately control longer-term rill and/or gully initiation and
development. Provide information on required "overdesign" of the cover thickness
needed to accommodate maximum predicted gully depths and locations.
4. Provide additional detailed cross sections showing every interface that will occur
between sideslope cover layers and topslope cover layers. Demonstrate that all
applicable filter criteria will be met for each interface between each topslope cover layer
component and the proposed granular filter layer on the sideslope, including standard
filter gradation criteria as well as applicable permeability filter criteria (e.g., for filter
layer underlying riprap on sideslope areas). Consider filter criteria for preventing
migration of granular materials into an adjacent coarser grained granular layer (e.g..
Nelson et al. 1986, Equation 4.35); for preventing piping of finer grained cohesionless
soil particles into an adjacent coarser-grained material layer (e.g., Cedegren 1989,
Equation 5.3); and for preventing erosion of a finer-grained material layer from
occurring over the long term as a result of flows in an adjacent coarser (filter zone) layer
(e.g.. Nelson et al. 1986, Equation 4.36). Include consideration of different specific filter
stability criteria (e.g., NRCS 1994, Tables 26-1 and 26-2) for determining the maximum
allowable D15 of a granular filter layer material for preventing erosion of any adjacent
layer (e.g., sacrificial soil layer) consisting of fine-grained/finer-grained particles, as a
function of soil type. Address applicable filter permeability criteria for the filter layer in
the sideslope cover system, including Table 26-3 of NRCS 1994.
5. Provide revised cover system cross sections to include a thicker riprap layer on the cover
sideslope areas (i.e., minimum thickness of 1.5 times the D50 of the rock rip size of 7.4
inches, or the D100 of the rock rip rap materials, whichever is greater) to bring the cover
design into compliance with recommendations contained in Section 2.1.2 of NUREG-
1623 (NRC 2002).
6. Provide revised constmction drawings for the final cover that preclude the presence of
low areas that have the potential for experiencing fiiture concentrated flows (e.g., portion
of cover overlying Cell 2 as depicted on Section B-3 on Drawing TRC-7) and that avoid
areas having abmpt changes in slope gradient across the cells, (e.g., areas of cover
having proposed 5h:lv slopes shown on Sections B-3 and C-3 on Drawings TRC-6 and
TRC-7 and Detail 7/8 on Drawing TRC-8, etc..) to be consistent with UAC R313-24-4
10CFR40, Appendix A, Criterion 4.
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TECHNICAL MEMORANDUM
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8.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan.5.0 R313-24-4;
10CFR40, Appendix A, Criterion 4; INT 08/1; Technical Analysis - Erosion
Stability Analysis
IN ITS RESPONSE, EFR provided, as requested, revised PMP calculations using the methods
described by Jensen 1995 and Jensen 2003.
IN ITS RESPONSE, EFR indicated that the Thornton and Abt 2008procedure is applicable to
soil-covered slopes but is not applicable to the flatter topslope areas only, where the Temple et
al 1987 method was instead used to evaluate long-term erosional stability.
IN ITS RESPONSE, EFR also revised the previously proposed embankment erosion protection
design to include use of angular, rather than rounded riprap, on the southern and eastern slopes
of Cells 4A and 4B and provided revised erosional stability analyses (included in Attachment C,
which will he incorporated as a revised Appendix G in the next version of the Updated Tailings
Cover Design Report [Appendix D of the Reclamation Plan]) for that angular riprap. This
resulted in a change in the riprap sizing on the embankment slopes for all areas experiencing
non-accumulating flows.
IN ITS RESPONSE, EFR provided revised calculations to demonstrate that applicable filter
gradation criteria for the various interfaces in the cover system layer components will be
achieved. The calculations used updated results of laboratory tests conducted on additional
samples of cover borrow materials collected in April 2012. Filter gradation criteria of NRCS
1994, Nelson et al 1986, and Cedegren 1989 were evaluated.
IN ITS RESPONSE, EFR indicated that the Construction Drawings will be revised to show the
filter and rock riprap layers.
The interrogatory requested that EFR address the minimum required thickness ofthe riprap
layer on the cover system and the inclinations needed in certain areas ofthe cover to minimize
potential flow concentration and avoid abrupt sloe changes.
IN ITS RESPONSE, EFR indicated that the revised Drawings will show a minimum thickness of
1.5 times the D50 of the rock riprap size, or the Djoo (whichever is greater) and that Section B-3
on Drawing TRC-7 will be revised to show the correct direction of the 0.5 percent slope to be
toward the south to match the plan view shown on Drawing TRC-3. The 5H: IV slopes shown on
the cover topslope will be revised to be 10H:1 V. The drawing updates will be included in the
next revision of the Reclamation Plan after approval of the final cover design.
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TECHNICAL MEMORANDUM
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8.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0; R313-24-4; 10CFR40, Appendix A, Criterion 4; INT 08/1:
Technical Analysis - Erosion Stability Analysis
The revised calculated 1-hr and 6-hr duration PMP values are equal to or smaller in
magnitude than the respective PMP values previously determined (8.3 inches and 10.0
inches, respectively) using the method of Hansen et al. 1984. The existing design is, thus,
oversized relative to precipitation projected to occur at the site. Therefore, the previous
analyses are considered acceptable and bounding.
Review of the topslope erosional stability calculations indicates that these analyses are not
complete and that the validity of certain assumptions used in these calculations has not
been adequately demonstrated. Missing from these analyses, for example, are a sensitivity
analysis case of bare soil conditions occurring on soil-only topslope surfaces (e.g., "uniform
weathered earth" or bare soil condition) to simulate a lack of vegetation on these topslope
areas, and a full analysis and justification for the estimated Manning's "n" values
appropriate for the soil-only surfaces, and gravel/soil admixture surfaces. For example, the
response did not distinguish between an appropriate "n" value for uniform weathered
earth conditions and "n" values for vegetated conditions; e.g., n = ( UR^ + ns^ + n^p^ -
[0.0156] )*/2 (Temple et al. 1987, p. 5).
Additionally, in the erosion analyses, EFR assumed a default flow concentration factor of 3,
in accordance with recommendations in NUREG-1623 (NRC 2002). However, this
assumption is valid only if uniform grading will be done during construction and ^
differential settlement has been shown to be insignificant. As discussed in Section 3.3 above
regarding the Response to Rd 1 Interrogatory 03/1 and in Section 7.0 regarding the
Response to Rd 1 Interrogatory 07/1, neither the ability to construct the proposed flat
topslope areas to a uniform slope nor the potential for differential settlement to occur in
the tailings management area embankment after closure have been adequately .
demonstrated.
The EFR response and calculations and methodologies relating to sizing of angular and
rounded riprap on the different sideslopes of the tailings cells area are considered
acceptable.
The EFR response, calculations, and methodologies relating to evaluation of the filter
gradation criteria are considered acceptable.
EFR committed to, but did not provide revised Drawings, revised CQA/CQC Plan, and
revised Technical Specifications showing the filter and rock riprap layers. These revised
documents will need to be reviewed, when available, to verify that these changes have been
made. Because these revised documents were not submitted in its interrogatory response,
this interrogatory will remain open.
EFR committed to, but did not provide revised Drawings showing the changes indicated
for the rock riprap layer minimum thickness and cross sections . The revised drawings will
need to be reviewed, when available, to verify that these changes have been made. Because
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
these revised documents were not submitted in its interrogatory response, this
interrogatory will remain open.
9.0 Liquefaction
9.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; 10CFR40,
Appendix A, Criterion 1; INT 09/1; Liquefaction
The interrogatory requested that EFR do the following:
Refer to Section 4.8 and Appendices C and F to the Appendix D, Updated Tailings Cover Design
Report of the Reclamation Plan, Rev. 5: >
1. Provide revised liquefaction analyses that rely upon actual site-specific data for the tailings
materials, rather than assumed parameters. In doing so, revise the Reclamation Plan tp
correctly and defensibly characterize tailings properties consistent with these revisions
throughout the document.
2. Correct apparent errors and conduct revised analyses using parameter values that are based
on site-specific data. Correct discrepancies between calculated results and summarized,
reported results.
3. Demonstrate that conditions assumed for liquefaction analyses are consistent with or
conservative compared to results of tailings dewatering analyses. If this is not tme, revise
liquefaction analyses to be consistent with or conservative compared to results of tailings
dewatering analyses, report results, and demonstrate that impoundments will remain stable
v^th regard to liquefaction.
9.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan_5.0 R313-24-4;
10CFR40, Appendix A, Criterion 1; INT 09/1; Liquefaction
IN ITS RESPONSE, EFR indicated that the liquefaction analyses were revised to be applicable
for long-term steady-state pore pressure conditions within the tailings, and are consistent with
regards to the tailings dewatering analyses. The revised analyses also incorporate the update to
the previous seismic study (provided as Attachment A to the May 31, 2012 response document).
The weight of the cover system has also been included in the analyses.
EFR stated that a constant Standard Penetration Test (SPT) blow count (n-value) of 2 blows in
12 inches (uncorrected) was assumed for the tailings zones that will remain saturated under
long-term steady state conditions. EFR indicated that an uncorrected n-value of 2 is considered
to be a reasonable "lower-bound" estimate of the uncorrected blow counts for saturated tailings
based upon a comparison with similar uranium tailings at other sites, and is a more conservative
assumption than was used in previous analyses. Previous analyses assumed a constant n-value of
4 to represent the in-situ state of the tailings.
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EFR stated that unsaturated tailings zones are not be susceptible to liquefaction and were not
included in the analyses. The long-term dry density of the tailings was revised to be 90 pcf to be
consistent with the value used for the updated radon emanation analyses. The revised
liquefaction analyses are provided as Attachment F and summarized in the Table 1 below.
The computed factors of safety against liquefaction range from 1.76 to 2.28. Based on these
results, EFR concluded that the tailings are judged not considered to be susceptible to
earthquake-induced liquefaction during the design seismic event.
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TECHNICAL MEMORANDUM
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Table 1. Summary of Liquefaction Results
Depth from
Top of Cover
(ft)
Saturated
Thickness (ft)
CSR CRR 7,5 MSF Factor of
Safety
Ceil 2
31.7 0 0.113 0.096 1.77 1.90
34.7 3 0.109 0.096 1.77 1.83
37.7 6 0.104 0.095 1.77 1.79
40.7 9 0.099 0.095 1.77 1.77
43.7 12 0.095 0.095 1.77 1.76
Cells
37.0 0 0.085 0.095 1.77 1.97
40.0 3 0.087 0.095 1.77 1.93
43.0 6 0.088 0.095 1.77 1.91
46.0 9 0.088 0.094 1.77 1.90
49.0 12 0.087 0.094 1.77 1.91
Cells 4A/4B
12.0 0.33 0.097 0.099 1.77 1.82
15.0 0.33 0.096 0.099 ' 1.77 1.82
18.0 0.33 0.095 0.098 1.77 1.83
21.0 0.33 0.094 0.097 1.77 1.83
24.0 0.33 0.093 0.097 1.77 1.84
27.0 033 0.092 0.096 1.77 1.86
30.0 0.33 0.090 0.096 1.77 1.88
33.0 0.33 0.089 0.095 1.77 1.90
36.0 0.33 0.087 0.095 1.77 1.94
39.0 0.33 0.084 0.095 1.77 1.99
42.0 0.33 0.082 0.094 1.77 2.05
45 0 0.33 0.079 0.094 1.77 2.12
48.0 033 0.076 0.094 1.77 2.19
51.0 033 0.073 0 094 1.77 2.28
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IN ITS RESPONSE, EFR also indicated that the revised liquefaction analyses are consistent
with regards to the tailings dewatering analyses.
9.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0; R313-24-4; 10CFR40, Appendix A, Criterion 1; INT 09/1;
Liquefaction
In the Rd 1 interrogatory, EFR was requested to "provide revised liquefaction analyses
that rely upon actual site-specific data for the tailings materials, rather than assumed
parameters." EFR's response to this Interrogatory states that "a constant Standard
Penetration Test (SPT) blow count (n-value) of 2 blows in 12 inches (uncorrected) is
assumed for the tailings zones that will remain saturated under long-term steady state
conditions." While this assumption of 2 blows in 12 inches (uncorrected) is a conservative
reinterpretation of the previously assumed value of 4 blows in 12 inches, it is still only an
assumption; it is not based on data. It is again requested that site-specific data for the
materials be used in analyses, not assumed data. Alternatively, EFR should use, and
provide adequate justification for demonstrating that the most reasonably conservative
parameter values possible (are used) in all calculations.
The assumed SPT blowcounts are subsequently corrected using a fines content of 30, said
to be based on an average of laboratory test values. Sands with this large of fines content
are typically quite resistant to liquefaction (hence the much greater blow counts after the
fines correction). Since the fines content value used to characterize the tailings is based on
an average value (and given that the effect of fines content on liquefaction resistance is not
linear), it is more appropriate to use a lower bound estimate of fines content rather than
average value; otherwise, a false factor of safety may result for some of the coarser-grained
materials. Again, as stated in the previous interrogatory, consideration should be given to
the potential variation of properties of the tailings.
The liquefaction analyses presented in Attachment F use a peak ground acceleration of 0.15
g and a moment magnitude of 6.0. These values are consistent with those of revised
probabilistic seismic hazard analyses. However, as part of the earlier deterministic
analysis, Tetra Tech (2010) estimated a magnitude 6.3 for a random background event,
said to be consistent with that used in previous seismic evaluations performed for sites in
the Colorado plateau. Please clearly identify and justify the more appropriate value to use
in the analyses, and revise analyses as needed.
The liquefaction analyses presented in Attachment F uses a dry unit weight of tailings of 90
pcf. Page C-4 ofthe REC plan (Denison Mines 2011) indicates that the dry unit weight of
the tailings is 91.4 pcf, rather than 90 pcf. The dry unit weight of tailings used in the
settlement analyses in Attachment E appears be 86.3 pcf. In the previous Interrogatory, it
was stated that "consistent characterization of the tailings throughout the report seems to
be needed." This issue remains unaddressed.
In the simplified liquefaction analysis procedure, the parameter K,, which accounts for
effects of confining stress is not used. At the base of the tailings, the currently computed
effective vertical overburden stress is nearly two tons per square foot. At this value. Figure
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TECHNICAL MEMORANDUM
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14 of Youd et al. (2001) shows the value of Kp for sands to be about 0.81, which would tend
to reduce the as-calculated factor of safefy. The factors of safety should be recalculated
including the correction factor Ko, or alternatively exclusion of this factor from analysis
should be justified.
In the liquefaction analysis presented in the revised Attachment F, there appears to be
multiple inconsistencies regarding the thicknesses of the various components of the cover
system for each of the cells (and hence the stresses used in the analysis may be incorrect).
Normal stresses calculated in the liquefaction analysis sheet are associated with assumed
cover-system soil thicknesses, which appear in some instances to be too high, as well as with
assumed relative compactions, some of which are too high. For example, the thickness of
random fill material at 95% of Standard Proctor dry density in the cover is stated in the
liquefaction analysis to be 4.7 feet for Cell 2. This appears to be too thick. Therefore, the
results of the liquefaction analysis itself, which depend on the "compacted cover"
thickness, apparently are in error. The entire design cover system in the liquefaction
analysis, from top to bottom, is claimed in the liquefaction sheet to be as follows:
Topsoil rock mulch: 0.5 feet thick.
Random fill at 85% of Standard Proctor dry density: 3.5 feet
Random fill at 95% of Standard Proctor dry density: 4.7 feet
Grading fill at 80% of Standard Proctor dry density: 2.5 feet
The assertion that the value of 4.7 feet appears to be too high for the random fill at 95% of
Standard Proctor dry density can be demonstrated from a number of sources. Figure 2.2 in
the Revised ICTM Report (Denison Mines 2010) provides a "generalized" cross-sectional
view of the cover system for the site and gives the purported general cover design is as
follows:
Topsoil rock mulch: 0.5 feet thick.
Random fill at 85% of Standard Proctor dry density: 3.5 feet
Random fill at 95% of Standard Proctor dry density: 2.8 feet
Grading fill at 80% of Standard Proctor dry density: 2.5 feet
The random fill at 95% of Standard Proctor dry density has a thickness listed above of
only 2.8 feet, not 4.7 feet. The REC plan (Denison Mines 2011) offers similar information,
but with the thickness of random fill at 95% of Standard Proctor dry density being said to
be only 2.5 feet. However, this generalized cross-sectional view of the cover system also is
considerably different compared to plans for actual constructed thicknesses in Cells 2 and
3. To obtain a more accurate value for planned thickness of random fill at 95% of
Standard Proctor dry density, it is necessary to turn to the engineering drawings. A check
can be made of the value used in the liquefaction analysis by comparing it against
"compacted cover" values shown for Cell 2 in Sheet TRC-7 ofthe REC Plan, Revision 5.0
(Denison Mines 2011). Sheet TRC-7 is titled, "Cover over Cell 2 Cross Sections." These
cross sections of the planned Cell 2 cover system show a maximum thickness for the
"compacted cover", representing the random fill at 95% of Standard Proctor dry density,
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of about two feet. However, that exists only in a few places. Cross Section A shows only
about 40% ofthe cell along that cross-sectional line having any "compacted cover"
whatsoever, with an average thickness of only about one foot where that "compacted
cover" does exist. About 60% ofthe cell along Cross Section A has no cover of 95% of
Standard Proctor dry density at all.
Cross Section B shows only about 25% of the cell along that cross-sectional line having any
"compacted cover" of 95% of Standard Proctor dry density whatsoever, with an average
thickness of about one foot where the compacted soil does exist. 75% of the cell along that
cross section has no "compacted cover" of 95% of Standard Proctor dry density at all.
Cross Section C shows only about 25% ofthe cell along that cross-sectional line having any
"compacted cover" of 95% of Standard Proctor dry density whatsoever, with an average
thickness of one foot or less where the "compacted cover" exists. Sheet TRC-2 also
confirms this, but in plan view. Cross Section C shows about 75% of the cell along that
cross-sectional line with no cover having 95% of Standard Proctor dry density at all.
Assuming that the cross-sections provide a representative cross-sectional view of the cover
system in Cell 2, it appears that, on average, to a rough approximation (assuming that each
cross-section represents one-third of the cover), coverage of the cell by any 95%-of-
Standard-Proctor "compacted cover" at all exists on only a little more than [(0.333)(0.40) +
(0.333)(0.25) + (0.333)(0.25)1 = 0.3, or three-tenths (3/10), ofthe cell. The average thickness
of "compacted cover" at the cell, averaged over the cell's entire area, is thus only about
(0.3)(1 ft) = 0.3 ft.
The liquefaction analysis sheet uses a value for the thickness of "compacted cover" having
95% of Standard Proctor dry density that happens to be [(4.7 - 0.3)/0.3] x 100% = 1470%
in excess of the actual value. In other words, the thickness of the random fill at 95% of
Standard Proctor dry density assumed in liquefaction analysis is 15.7 times that value.
Please address these inconsistencies in the liquefaction analysis spreadsheet calculations
and provide correct values for the thickness ofthe random fill at 95% of Standard Proctor
dry density.
Apart from issues associated with characterization of the cover system components, the
liquefaction analysis spreadsheet calculations presented in Attachment F indicated a
tailings surface elevation for Cell 2 of 5613.5 feet. 5613.5 feet is the approximate surface
elevation for much of the tailings in Cell 2. However, tailings in the vicinity of Cross Section
C in Cell 2 have much higher elevations in the northern half of the cell. There, the
elevations reach to 5623 feet. Also, the liquefaction analysis spreadsheet calculation shows
that the water surface elevation for Cell 2 is 5593.03 ft amsl. For of the second quarter of
2012, on May 29th, the reported depth to water in the tailings slimes in Cell 2 was
measured as 21.10 ft (EFR 2012). The top of slimes drain pipe is at an elevation of 5618.73
ft amsl (personal communication with Russ Topham of the Division on October 5,2012,
who reported receiving it from Garrin Palmer of EFR on October 5,2012). So, the
calculated head of water in the tailings is estimated to be 5618.73 ft amsl minus 21.10 ft, or
5597.63 ft amsl. This is 4.6 feet higher than what is shown in the liquefaction analysis sheet.
These values should be corrected.
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As is the case for Cell 2, so it is for Cell 3 that actual planned thicknesses of various layers
at different percentages of Standard Proctor dry densities, or at different compactions,
greatly vary from what the liquefaction sheet shows. Sheet TRC-6 in the REC Plan
(Denison Mines 2011) demonstrates this. Please fix the stated thickness values. Also, since
the errors in thicknesses translate to errors in calculated normal stresses induced by cover
systems in the various cells, and other calculations on the liquefaction analysis sheet, please
be sure that these are fixed as well.
The liquefaction analysis spreadsheet calculations identify the tailings thickness for Cell 2
as 32.5 feet, that for Cell 3 as 38.5 feet, and that for Cells 4A/B as 40.5 feet. Table F.l of
Denison Mines 2011 is cited. Table F.l and the Attachment F-2, Settlement Analysis
spreadsheets in Denison Mines 2011 likewise provide figures of 32.5,38.5 and 40.5 feet for
the tailings thicknesses for Cells 2,3, and 4A/B, respectively. These figures, however,
appear to conflict with the tailings thickness for Cells 2 and 3 given on Page C-2 of the
Response text of "approximately 30 feet" and "the tailings thickness for Cells 4A/B of
approximately 42 feet" (Denison Mines, 2011). These inconsistencies should be fixed.
It can be seen, based on 1980 as-built drawing information from Energy Fuels Nuclear,
Inc., as shown on Sheet TRC-7 of Denison Mines (2011) that, for most of the Cell 2, the
elevation of the tailings surface is 5613 ft amsl. This knowledge, coupled with some
additional information, can lead to a better understanding of maximum saturated
thickness in the tailings of Cell 2. Assuming for the moment that the Denison Mines (2011)
Table F.l 32.5 feet value is correct, this means that the nominal base of the tailings must be,
on average, at about 5613 ft amsl minus 32.5 feet, or 5580.5 ft amsl. Since, as calculated
above, the head of water in the tailings is 5597.63 ft amsl, it follows that the average
saturated thickness of the tailings in Cell 2 is 5597.63 ft amsl minus 5580.5 ft amsl, or 17.1
feet. This compares with a value of 12.03 feet claimed for maximum saturated thickness in
the liquefaction sheet. The latter number appears to be off by 5.07 feet, which would be a
30% error. This may substantively change a number of liquefaction calculations. Please
correct the saturated thickness in the liquefaction sheet.
From the previous calculations for Cell 2, it is observed that the saturated thickness is
about 30% greater than claimed in the liquefaction analysis. This has effects on
calculations for effective overburden stress and other consequent calculations. These effects
can be accounted for to some extent. The saturated zone starts about 4.5 feet higher than
shown on the liquefaction analysis sheet, at approximately 5597.63 ft amsl, not at 5593.03 ft
amsl. This means that 4.6 feet of tailings must be accounted for with a 120.3 pcf saturated
specific weight compared to old approach of (if that 4.6 feet of tailings is assumed to have a
moist specific weight of 95.40 pcf). Secondly, it changes the values of effective stress at each
deeper depth analyzed, since it also shifts the elevation vs. water pressure curve up. The
Division request that EFR please make appropriate changes to the effective overburden
stress calculations, or justify not doing so, not only for Cell 2, but for other cells, as needed.
In summary, based on a review of the information provided and in consideration of the
issues previously discussed, the Division finds that several of the issues identified in the
Interrogatory remain unaddressed, and consequently, the Division is unable to assess the
correctness of EFR's conclusions regarding performance of the tailings impoundment cells
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WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
relative to liquefaction. In particular, no explicit discussion relating the results of the
tailings dewatering analysis to the water levels used in the liquefaction analyses was
presented. Also, parameters regarding the tailings characterization continue to be assumed
(although how some are more conservatively selected) rather than being based on site-
specific data. If assumed data are used, it should reflect the most reasonably conservative
values possible. While adverse performance seems unlikely based on the relatively high
factors of safefy with respect to liquefaction potential currently calculated, there are
enough inconsistencies in the analyses that further evaluation is merited.
10.0 Frost Penetration Analysis
10.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; 10CFR40,
APPENDIX A, CRITERION 6; INT 08/1; Technical Analyses - Frost Penetration
Analysis
The interrogatory requested that EFR do the following:
Refer to Section 4.3 of Appendix D (Updated Tailings Cover Design Report) and Appendix B
(Freeze/Thaw Modeling) to Appendix D to the Reclamation Plan Rev. 5.0:
1. Please revise fi:eeze/thaw analyses to incorporate the following:
. a. Extrapolation of frost depth to recurrence interval to a minimum period of up
to 1,000 years, to the extent practicable, or, to not less than 200 years, using a
Gumbel extreme statistics (probability functions) approach (e.g.. Smith and
Rager 2002; Smith 1999; Yevjevich 1982).
b. Additional justification for selection of an N -factor (surface temperature
correction factor) of 0.6, instead of an N -factor of 0.7, based on published
recommendations (e.g., DOE 1989).
c. Additional justification that using climate data for Grand Junction, Colorado
in the Berggren Model Formula (BMF) is representative of site conditions at
the White Mesa site Address the considerably lower elevation and average
warmer temperatures of Grand Junction compared to the White Mesa site.
Either (1) prepare and report results of the BMF calculations using a default
location having an elevation and Design Freezing Index equal to or greater
than those of the White Mesa site AND mean average temperatures equal to
or less than those of the White Mesa site OR (2) justify that the Grand
Junction data is applicable and representative as input to the BMF calculations
for the White Mesa site.
2. Based on the results of the revised frost penetration analysis, justify revised soil
parameter values for soils within the cover system above the projected frost
penetration depth considering the effects of repeated freezing and thawing over
the recurrence interval considered (referred to in Item 1 .a above). Use these
parameter values in performance assessment modeling, including infiltration
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
modeling and radon attenuation modeling, consistent with recommendation
provided in Sections 2.5 and 5.1 of NUREG-1620 (NRC 2003a).
3. If applicable after addressing the instmctions stated above, revise Appendix B to
Appendix D of the Reclamation Plan to ensure that all intended text is present in
the document.
10.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan_5.0 R313-24-4;
10CFR40, Appendix A, Criterion 6; INT 10/1; Technical Analyses - Frost
Penetration Analysis
IN ITS RESPONSE, EFR provided a revised frost depth penetration analysis for the currently
proposed final cover system as Attachment C to its May 31, 2012 Response (partial) to the
Round 1 Interrogatories on the Rev. 5.0 Reclamation Plan. The freeze/thaw analyses were
revised to use Gumbel extreme statistics approach for a time period of200 years. An N-factor of
0.7 and climate data from the Blanding, Utah was usedfor the analyses. The resulting frost
penetration depth was estimated as 32 inches. EFR indicated that this frost analysis will be
revised after approval of the conceptual final cover design has been obtained.
IN ITS RESPONSE, EFR also indicated that revised infiltration and radon emanation modeling
have been completed that reflect modifications to the hydraulic and physical properties ofthe
cover caused by freeze/thaw processes based on recommendations provided in Benson et al
2011. The results of the revised modeling are provided as part of EFR's Response to the Round 1
Interrogatories on the Revised ICTM Report EFR also indicated that Appendix B to Appendix D
(Updated Tailings Cover Design Report) of the next revision of the Reclamation Plan will be
updated to incorporate the revised freeze/thaw analyses.
10.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0; R313-24-4; 10CFR40, Appendix A^Criterion 6; INT 10/1;
Technical Analyses - Frost Penetration Analysis
The May 31,2012 EFR response and calculations and methodologies used for completing
the revised frost depth analysis are considered acceptable, with the one exception described
in the following paragraph.
The Division notes that in the revised infiltration and revised radon emanation modeling
most recently completed by EFR, use of NRC-recommended adjusted porosify and bulk
densify values was not considered. The Division requests that EFR conduct a revised radon
emanation modeling sensitivify analysis (as well as conduct a revised infiltration sensitivify
analysis) for the approved final cover for a scenario that incorporates adjusted bulk
densify and porosify values (or adjusted appropriate other soil parameters in the
infiltration analysis) for soils in the upper zone of the cover system potentially impacted by
the predicted maximum frost penetration. Adjusted §oil properfy values used in the
simulations should either consist of adjusted values derived in a manner consistent with
NRC recommendations for adjusting such properties in frost-impacted soils for radon flux
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
emanation calculations (NRC 2003a, Section 5.1.3), or adjusted values derived/assigned in
manner consistent with recommendations provided in Benson et al. 2011, whichever is
more conservative for the respective simulations. (See also discussion in Section 1.3 ofthe
Technical Memorandum, White Mesa Mill Site - Revised ICTM Report Review addressing
EFR's Response to Rd 1 Interrogatory 01/1 on the Revised Infiltration and Contaminant
Transport Modeling Report).
The final revised Appendix B to Appendix D will need to be reviewed, when available, to
verify that the revised frost depth information has been incorporated. The final revised
frost depth analysis completed once the final cover design has been approved Drawings will
need to be reviewed, when available, to verify that the revised frost depth calculation has
addressed elements included in this request and has appropriately addressed any changes
in the cover design, as applicable. Because these revised documents were not submitted
with the response, this interrogatory will remain open.
11.0 Vegetation and Biointrusion Evaluation and Revegetation Plan
11.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; 10CFR40,
Appendix A, INT 11/1; Vegetation and Biointrusion Evaluation and Revegetation
Plan
The interrogatory requested that EFR do the following:
Refer to Section 1.7.1, 3.3.1.0 and Appendices D and J of the Reclamation Plan Rev. 5.0: Please
provide the following:
1. Provide additional information (e.g., in the form of a survey and additional
documentation of existing animal and vegetation species that exist at the White Mesa
site and nearby surrounding region at this time to update the older information
provided earlier.
2. Update the list of plant and animal species to include plant and animal species (e.g.
burrowing animals) that could reasonably be expected to inhabit or colonize the
White Mesa site within the required performance period of the embankment (1,000
years, and in no case less than 200 years). In revising these lists, account for the types
of vegetation and soils present in the vicinity of the White Mesa site and proximity to
the high quality northem pocket gopher and badger habitat indicated in Utah
distribution maps (Utah Division of Wildlife Resources).
3. Please report the estimated range of burrowing depths and burrow densities for
animal species found at the site and nearby surrounding region (once the updated
study requested above is complete), and for burrowing species that may reasonably be
expected to inhabit the site within the required performance period of the
embankment (1,000 years, and in no case less than 200 years). Please comment on the
root densities provided in Appendix D of the ICTM report. Indicate whether the
correct root density units were used in Table D-3 and Figure D-1. Also verify that the
correct values were used in the HYDRUS-2D infiltration model, since an erroneously
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
high value of root density could overestimate plant transpiration and underestimate
infiltration.
4. Rectify the mischaracterization of two plant species as presented in the two
referenced documents (Festuca ovina and common yarrow).
5. Provide additional documentation to support conclusions made regarding the ability
of the proposed vegetation to establish at the cover percentages predicted. Also,
provide additional discussion regarding the potential sustainability ofthe cover design
and characteristics as proposed relative to changes that could occur due to the effects
of natural succession and climate change during the performance period (1,000 years,
and in no case less than 200 years).
6. Perform and report results of an additional infiltration sensitivity analysis to address
the effects of deep-rooted plants projected by the updated analysis described above.
In particular, account for any potentially deep-rooted species to assess the their
effects of such deep-rooted species on the characteristics of soil layers in the
embankment cover system. Please provide a forecasted percentage of potential
species invasions in the ET cover system.
11.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan_5.0 R313-24-4;
10CFR40, Appendix A; INT 11/1; Vegetation and Biointrusion Evaluation and
Revegetation Plan
IN ITS RESPONSE, EFR indicated the following:
1. A plant and animal survey was conducted at the White Mesa site and surrounding area in
June 2012 to update information provided in the Dames and Moore Environmental
Report (1978). Plant cover was estimated along point intercept transects in the Big
Sagebrush community type and through this survey the plant species that exist at the site
and surrounding area have been updated and included in a revision of Appendix D to the
Updated Tailings Cover Design Report (Appendix D of the Reclamation Plan, Revision
5.0). The revised appendix is provided as Attachment G. A survey of burrowing animals
was also conducted with a focus on prairie dogs, badgers and northern pocket gophers.
This survey was conducted in both the Big Sagebrush and Juniper communities either on
site on in the surrounding area. Results for this survey are also presented in Attachment
G;
2. A plant and animal survey was conducted at the White Mesa site and surrounding area in
June 2012. The information from these surveys was used to update the list of plant and
burrowing animal species that could reasonably be expected to inhabit or colonize the
White Mesa site within the required performance period of200 to 1,000 years. EFR
indicated that the results of these surveys are included in Attachment G;
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
3. The estimated range of burrowing depths and burrow densities for animal species found
at the site and nearby surrounding region are reported in Attachment G. The June 2012
animal survey conducted in the area of the Mill site provided burrow densities and an
updated literature search was conducted on burrow depths for animal species that may
reasonably be expected to inhabit the site within the required performance period;
4. The root densities provided in Appendix D of the Revised Infiltration and Contaminant
Transport Modeling (ICTM) Report are incorrect because of a calculation error.
Updated and recalculated root biomass values are shown in Table 1 below. These
corrected values were used in the revised HYDRUS-ID infiltration model and results are
provided as part of a second response document to the Revised ICTM Report;
5. The seed mixture proposedfor the ET cover at the White Mesa Mill site consists of native
and introduced species. The majority of species are native to Utah and two species
(Pubescent wheatgrass and sheep fescue) have been introduced to North America. Sheep
fescue was introduced from Europe in the 19th century, is commonly found in Utah and
highly used as a reclamation species. Pubescent wheatgrass was introduced from
Eurasia in 1907 and is also distributed in Utah from reclamation seedings over the past
100 years;
6. Common yarrow (Achillea millefolium, var. occidentalis) is native to North America and
is found in Utah, according to the USDA Natural Resources Conservation Service's
Plant Database (http://plants.usda.gov/java/). However, seed that is most available for
common yarrow (Achillea millefolium) is of an introduced origin and is commonly used
in reclamation plantings in Utah and throughout the western U.S. Seed of the native
variety, occidentalis, will be used in the seed mixture if seed is available. If the native
variety is not available, then the more common introduced variety will be used;
7. Galleta (Hilaria jamesii) has been added to the proposed seed mixture (Table 2), which
can be found in the Attachment G. Galleta is a native warm season grass that is very
common at the Mill site and makes an excellent addition to the proposed mixture;
8. Additional documentation to support conclusions made regarding the ability of the
proposed vegetation to achieve predicted cover percentages is provided in the
Attachment G. Plant cover was measured in the Big Sagebrush community and results
support the predicted cover percentages for the plant community that will he established
on the ET cover system. In addition, a more in-depth discussion is presented in
Attachment G regarding potential sustainability of the cover design in relation to
changes that could occur during natural succession and under possible climate change
scenarios;
9. Revisions to the HYDRUS-ID infiltration model and results are provided as part of a
second response document to the Revised ICTM Report; and
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10. A discussion of the forecasted percentages ofpotential species invasions in the ET cover
system is provided in [Revised] Attachment G.
Table 1. Corrected Root Biomass (Anticipated Performance Scenario and Reduced
Performance Scenario) for the White Mesa Mill Site
Depth (cm) Root Biomass Depth Anticipated
Performance (g/crr^)
Root Biomass Depth Reduced
Performance (g/cm^)
0-15 0.11 0.04
15-30 0.17 0.12
30-45 0.035 0.02
45-60 0.023 0.015
60-75 0.021 00.014*
75-90 0.019 0.0
90-107 0.011 0.0
* Maximum rooting depth under the reduced performance scenario would be 68 cm
Table 2. Species and Seeding Rates Proposed for ET Cover at the White Mesa Mill Site.
Scientific Name Common Name Variety Native/Introduced Seeding Rate
(lbs PLS/acre)f
Grasses
Pasccopyrum smithii Western wheatgrass Arriba Native 3.0
Pseudoroegneria
spicata
Bluehunch wheatgrass Goldar Native 3.0
Elymus trachycaulus Slender wheatgrass San Luis Native 2.0
Elymus lanceolatus Streambank wheatgrass Sodar Native 2.0
Elymus elymoides Squirreltail Toe Jam Native 2.0
Thinopyrum
intermedium
Pubescent wheatgrass Luna Introduced^ 1.0
Achnatherum
hymenoides
Indian ricegrass Paloma Native 4.0
Poa secunda Sandberg bluegrass Canbar Native 0.5
Festica ovina Sheep fescue Covar Introduced^ 1.0
Bouteloua gracilis Blue grama Hachita Native 1.0
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Table 2. Species and Seeding Rates Proposed for ET Cover at the White Mesa Mill Site.
Scientific Name Common Name Variety Native/Introduced Seeding Rate
(lbs PLS/acre)f
Hilaria jamesii Galleta Viva Native 2.0
Forbs
Achillea millefolium
var. occidentalis
Common yarrow No Variety Native 0.5
Artemesia
ludovociana
White Sage No Variety Native 0.5
Total 23.0
f Seeding rate is for broadcast seed and presented as pounds of pure live seed per acre (lbs PLS/acre)
t Introduced refers to species that have been 'introduced' from another geographic region, typically
outside of
North America. Also referred to as 'exotic' species.
11.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0; R313-24-4; 10CFR40, Appendix A; INT 11/1; Vegetation and
Biointrusion Evaluation and Revegetation Plan
The Division finds that EFR has addressed, in part, the items included in the interrogatory
and considerable useful new information has been provided. However, some additional
information is still needed to complete the responses, as described in the following
paragraphs.
EFR presented results of the vegetation survey in summary fashion and provided few
details. Are there survey reports describing methods and results in greater detail? Is there
data available for each transect location? Is there information on other plant species
observed but that did not have cover recorded at the transect points? The vegetation
survey results did not include an updated vegetation map or information on the current
vegetation in the reclamation cells. The map in the September 2011 Reclamation Plan
(Revision 5.0) is clearly inconsistent with the results of the vegetation sampling reported in
the August 15,2012 Responses to Interrogatories, in that 19.1% big sagebrush cover was
found at sample sites that are located in areas shown in Figure 17-1 as reseeded grassland
and controlled big sagebrush. Information should have been provided on the current
vegetation of the reclamation cells. The information provided does not provide an adequate
account of current vegetation or an explanation of the successional processes that have
occurred following previous disturbances and reclamation efforts.
Attachment G provides an updated seed mix, which now includes galleta. The total seeding
rate in Table D.l needs to be corrected to be 22.5 lbs PLS/acre. A column of PLS/square
foot should be added to this table (this information was previously provided for most
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WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
species in the September 2011 Appendix J Reclamation Plan). This mix is now correctly
characterized as containing both native and introduced species.
Information was provided on the ecological characteristics of each of the species in the seed
mix. However, no information was provided regarding past success or failure with these
species at the site during interim reclamation. Previous revegetation experience at the site
and changes in composition and cover over time, if available, need to be presented in order
to support the predicted cover percentages.
Table D.4. Please provide more explanation as to how the values in this table were derived.
Table D.9 provides levels of soil properties for stockpiled soils compared to sustainable
levels reported in the literature. These "sustainable levels" may or may not be achievable
or sustainable over a long term within the study area, depending on its environment. To
help determine realistic long-term expectations, soil properties should also be measured at
reference areas. To what extent will establishment of grassland vegetation contribute to
developing soil properties supporting sustainable vegetation?
The description of organic matter and nutrient amendments lacks sufficient detail. Provide
more information regarding quantities, potential sources, and suitabilify for sustained
growth?
How will institutional control be used to exclude grazing by livestock for the performance
period?
Weeds and weed management should be addressed. It is noted that a significant portion of
the vegetation over in the sagebrush areas surrounding the White Mesa Mill Site comes
from cheatgrass and Russian thistle, and that cheatgrass and jointed goat grass initially
dominated revegetation areas at Monticello.. What other weeds occur in the area or may
occur in the future? Use of a mix of hay and manure to provide soil organic matter could
introduce weeds.
Section D.4.5. of Attachment G , Supporting Documentation for (Rd 1) Interrogatory 11/1
(Revised Appendix D to the Updated Tailings Cover Design Report), first sentence
indicates that "monitoring of an alternative cover at the Monticello Mill Tailings Disposal
Site showed that the plant cover performed well over a seven year period." The last phrase
"plant cover performed well over a seven year period" should be reworded because
although cover goals for grasses were met later in the 7-year period, cover goals established
for the Monticello cover for shrubs species were not achieved despite significant shrub
planting efforts in in 2000 and in 2007 (e.g., see Sheader and Kastens [undated] circa 2007).
Please provide a reference for the statement that eight species provided 70% of the plant
cover at Monticello. The text in Revised Appendix D does not provide an indication of the
percentage vegetative cover comprised by weedy species including weedy cheatgrass and
Russian Thistle over that time period at Monticello and does not discuss how these species
may affect cover revegetation goals (evapotranspiration capabilities) established for the
Monticello or White Mesa cover systems.
Section D.7.2 addresses succession, including increase in sagebrush cover. The discussion
should acknowledge the establishment of big sagebrush and other shrubs on former seeded
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grassland and controlled sagebrush areas north of the Mill Site in the 35 years since the
original vegetation study, and discuss its relevance to the revegetation plan. The discussion
indicates that warm season grasses are expected to increase over time. Is there an existing
vegetation community in the region similar to that which is expected to develop? The
discussion also mentions pulse-dominated precipitation - are there expected changes in
seasonality of precipitation? An explanation should be provided as to why shrub species
that occur just south of, and at lower elevations than the tailings management areas
location,, such as four-wing saltbush, shadscale, blackbrush, and Mormon tea, would not
increase under potentially warmer and dryer future climate conditions at the site.
The Reclamation Plan (or revised Infiltration and Contaminant Transport Report) needs
to provide: (1) definition of clear, concise, and measurable revegetation acceptance
goals/criteria for the vegetation establishment on the tailings cell cover system, (2) a
description of how EFR will conduct periodic post-closure monitoring and reporting to the
Division ofthe vegetation community health, viability, success, and sustainability, (3) a
description of proposed action plans, schedules and deadlines for remedial actions if^when
needed to effectuate plant community success, and (4) similar follow-up monitoring of the
plant community/cover system to ensure successful performance before release of the
facility's surety bond and/or transfer of title to DOE. EFR should describe specific,
quantitative goals for shrub establishment (including rooting depths and minimum
acceptable shrub cover percentages) that consider the need for deeper rooted plants to
remove water that may accumulate lower in the cover profile in response to an
exceptionally wet year or successive wet years, especially given the lack of a capillary break
layer in the currently proposed cover design. In developing these descriptions, plans, and
goals, EFR should consider and address lessons learned from the post-closure monitoring
and maintenance activities and/or corrective revegetation measures required at the
Monticello, Utah tailings repository and other similar facilities in this regard (e.g., Waugh
2008; Sheader and Kastens undated, circa 2007; U.S. DOE 2007; Sheader and Kastens
[undated, circa 2007). EFR should assess the potential applicability and benefits of using
vegetation health monitoring tools/metrics such as the Cover Vegetation Index recently
implemented at the Monticello Repository (U.S. DOE 2009).
The Reclamation Plan should describe corrective measures that may be needed to
address/correct issues related to: (1) establishment of undesirable species, e.g., colonization
by certain undesired grass/weedy species that may have more limited water stress tolerance
than initially seeded grass species and/or that may outcompete planted grass species unless
controlled (e.g., Smesrud et al. 2012; Sheader and Kastens [undated, circa 2007]); (2) Seed
predation following seeding/reseeding efforts; (3)Possible low success rates resulting from
for shrub establishment efforts, etc.... Estimated costs for conducting these post-closure
activities, corrective actions, and reporting, once approved by the Division, will need to be
incorporated in the financial surety estimate.
The Revised Attachment G provided by EFR as part of its Response presents the results of
a June 1012 burrowing animal survey (Section D.5.3). However, as described above, the
results are presented in summary fashion and few of the necessary details are provided.
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Are there survey reports describing methods and results in greater detail? Is there data
available for each transect location? Does badger burrow density include feeding areas
(dug-out prey burrows)? The reported burrow_density for badger appears very low.
Additional information about potential burrow densities should be provided based on a
review ofthe literature. The analysis should consider both burrows dug by badgers for
their own use and digging while hunting.
Little information is presented on burrow densities, other than Gunnison prairie dog.
Results for Gunnison prairie dog are based on the June 2012 survey and do not consider
literature values. Information on burrow densities for Gunnison prairie dog should be
summarized by transect and the locations of prairie dog towns marked on a map. The
results need to be put in context by reference to literature, for example Lupis et al. 2007,
considering both regional densities, predicted range and habitat suitability. The statement
in Attachment D that prairie dogs are unlikely to occur because they prefer low plant cover
and short vegetation is not consistent with the description of habitats where they occur in
southeastern Utah in Lupis et al. 2007. Most of the grass species included in the seed mix
are reported to occur in grassland habitat occupied by this species in southeastern Utah.
They also occupy desert shrub habitats.
Table D.8. Ranges of depths for burrowing mammals mostly not provided, just maximum
depth, and based on a single citation per species. The "maximum" depth for Gunnison's
prairie dog of 122 cm from Verdolin et al 2008 should be correctly characterized as an
average depth reported from several studies. The actual maximum (mean plus 1 SD)
reported by Verdolin et al. 2008 appears to be 1.85 m. All ofthe numbers in this table
should be revisited to provide a range of maximum values reported in the literature and to
determine whether the maximum has been accurately stated.
Table D.6 and discussion. There is literature indicating that big sagebrush can root to
depths considerably below 180 cm. Please address and further explain this
finding/statement. Rooting depths of other shrubs that may occur should also be
considered.
Additional information needs to be presented to justify that the highly compacted zone will
minimize biointrusion by plant roots. Consider moisture conditions, potential degradation
when dry, behavior of roots related to soil moisture and gas exchange, and other factors.
Cite previous studies or observations of root growth relative to compacted soils.
12.0 Report Radon Barrier Effectiveness
12.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; 10CFR40,
Appendix A, Criterion 6(4); INT 12/1; Report Radon Barrier Effectiveness
The interrogatory requested that EFR do the following:
Refer to Reclamation Plan Rev. 5.0, Section 3 (Tailings Reclamation Plan) and Appendix D
(Updated Tailings Cover Design Report dated Sept 2011):
Please revise radon flux calculations using actual site-specific material properties data.
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a. Clearly demonstrate that values of material parameters:
1) Are reasonably conservative
2) Are based on site material samples, measured values, assumptions, or other
origins
3) Are based upon appropriate analytical methods and sufficient number of
representative samples for cover soils and tailings
4) Consider the variability and uncertainties in actual site-specific data.
5) Are consistent with anticipated constmction specifications
6) Are based upon representative long-term site conditions.
b. Justify values of material parameters used in the radon flux calculations
c. Demonstrate that test methods and their precision, accuracy, and applicability are
supported by suitable standards and procedures.
d. Justify that values chosen for radon emanation and diffusion coefficients are consistent
with long-term moisture contents projected to exist within tailings and cover materials in
the impoundments.
e. Demonstrate that the quality assurance program used in obtaining parameter data is
adequate
f Revise the design density and porosity values of cover soils to comply with the usual
compaction of 95% of Standard Proctor (D 698). Altematively, clearly justify the basis
for the lower compactions utilized in the radon flux calculations and their expected long-
term stability.
g. Please revise the tailings density, porosity, and moisture values to reflect expected long-
term conditions in each of the disposal units. Altematively, demonstrate the basis for the
long-term stability of the values used in the radon flux calculations.
h. Please utilize one of the two accepted methods for long-term moisture estimates (D 2325
or Rawls correlation) with representative samples. Altematively, justify the use of an
acceptable altemative method.
i. Please resolve or justify the discrepancy between the 91.4 pcf "best correlation" between
the Rawls and in-situ moisture data (Appendix D page C-4) and the density range of 94 to
111 pcf used in the radon flux calculations. Revise and report results of radon flux
calculations, as necessary to reflect the resulting changes.
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j. Please utilize a source term based on representative sampling and analysis ofthe sand,
slime, and mixed tailings to 12-ft depths in sufficient and representative locations of each
tailings area (e.g.. Cells 2, 3, 4A, and 4B.). Altematively, justify and use the average ore
grade method identified in Reg Guide 3.64 for the radon flux calculations.
k. Please justify the assumed value of zero for Ra-226 concentrations in cover soils by
sampling and measurement of background Ra-226 soil concentrations and comparison of
their values with corresponding representative measurements in the proposed cover soils.
Altematively, use values of Ra-226 concentrations in radon flux calculations that are
supported by cell-specific measurements.
1. Please utilize measured radon emanation coefficients that are representative ofthe sand,
slime, and mixed tailings in the various tailings cell areas; emanation coefficients
averaged over measurements for each tailings cell. Altematively, use default values
conservatively estimated from site-specific measurements.
m. Please utilize measured or calculated radon diffusion coefficients in radon flux
calculations that represent the long-term properties of the tailings and cover soil
materials.
n. Please provide written procedures for identifying and placing contaminated soils into the
disposal cell(s) and substantiating characterization data and site history.
o. Provide a revised radon emanation model that incorporates lower values of initial bulk
density for the erosion protection layer in the model. The bulk density value selected
needs to fall within the range of bulk densities that is recommended (approximately 1.2 to
1.8 g/cm3, or about 75 to 112 pcf) in the section entitied "Soil Requirements for
Sustainable Plant Growth" and listed in Table D-5 in Appendix D to the Reclamation
Plan as the recommended range required for promoting sustainable plant growth.
12.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPIan.5.0 R313-24-4;
10CFR40, Appendix A, Criterion 6(4); INT 12/1; Report Radon Barrier
Effectiveness
IN ITS RESPONSE, EFR indicated the following:
A site investigation to further evaluate cover borrow materials was conducted on April 19, 2012.
The results of laboratory testing on samples collected from the April 2012 investigation were
used to develop updated cover material parameters for radon emanation modeling. In addition,
other model parameters were further evaluated as necessary to address comments in this
interrogatory. The results of the updated analyses are provided in Attachment H as part ofthe
revised Appendix C, Radon Emanation Modeling, which will be included in the next version of
the Updated Tailings Cover Design Report (Appendix D of the Reclamation Plan).
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The radon emanation coefficient parameter was revised for the updated radon analyses
presented in Attachment H to he 0.20 based on recommendations in NUREG-1620 (NRC, 2003)
that states a "value of 0.20 may be estimated for tailings based on the literature, if supported by
limited site-specific measurements."
A radon coefficient used in the model for the cover layers was revised to be 0.35 for the updated
radon analyses presented in Attachment H. A value of 0.35 is the conservative default value used
in the RADON model
The radon diffusion coefficients can be calculated within the RADON model or input directly
using measured values (NRC, 2003). Although laboratory test data was available, the tests were
performed at porosities and water contents different than those estimated to represent long-term
conditions in the model Therefore the values were calculated within the RADON model The
revised radon modeling also used radon diffusion coefficients that are calculated within the
model.
The cover design consists of an evapotranspiration cover. The water storage layer will be
compacted to 85 percent of standard Proctor density and the lower random fill layer is estimated
to he compacted to 80 percent of standard Proctor density. Use of design density and porosity
values corresponding to 95 percent of standard Proctor density would be inconsistent with the
cover design.
The long-term tailings density was revised to be 90 pcf based on laboratory tests (Chen and
Associates, 1987 and Western Colorado Testing, 1999) and assuming the long-term density of
the tailings is at 85 percent ofthe average laboratory measured maximum dry density. The
porosity ofthe tailings was calculated using the dry density and the average measured specific
gravity of 2.75 based on laboratory tests (Chen and Associates, 1987 and Western Colorado
Testing 1999).
The long-term moisture content value for the tailings was assumed to be 6 percent in the
analyses presented in Denison (2011). This is the same value that was used for the revised radon
analyses. This is a conservative assumption, per NRC Regulatory Guide 3.64 (NRC, 1989),
which represents the lower bound for moisture in western soils and is typically used as a default
value for the long-term water content of tailings.
Laboratory results for, the 15 bar water contents for select samples from the April 19, 2012 field
investigation were used to estimate long-term water contents for the random fill and erosion
protection layers. This is discussed further in Attachment H.
The radon analyses were updated using the revised estimates for long-term water contents. This
response supersedes the response provided in the response document submitted May 31, 2012.
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The revised estimation of the radium-226 concentration activities used for the tailings is
provided in Attachment H.
Denison has established background values for Ra-226 in surface soil in the White Mesa Mill
area. These background values are very low, due to the absence of uranium mineralization in the
mill area. The cover soils that have been stockpiled are derived from the same geologic
formations as the soils measured for background values. Therefore a Ra-226 value for cover
soils of zero is appropriate in the radon fiux modeling, as outlined in NRC Regulatory Guide
3.64.
Procedures for identifying and placing contaminated soils is provided in Attachment A (Plans
and Technical Specifications) of the Reclamation Plan. Additional information on procedures for
identifying contaminated soils is provided in the responses to Interrogatory 20/1.
The density ofthe rock mulch erosion protection layer was revised to be based on the additional
laboratory testing ofpotential cover soils (see Attachment B.2). The previous density ofthe rock
mulch provided in Appendix D of the Reclamation Plan should was incorrectly listed as
124.2 pcf. It should have been listed as 107 pcf based on the historical laboratory testing results.
The updated rock mulch density is 106 pcf This value was used in the radon modeling.
12.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0; R313-24-4; 10CFR40, Appendix A, Criterion 6(4); INT 12/1;
Report Radon Barrier Effectiveness
The Division's assessment of the Response follows below:
As with a number other responses, EFR has deferred final resolution of issues to its
submission of the next revision of the Reclamation Plan. The Division requests that EFR
please submit the next revision of the Reclamation Plan that incorporates all changes
proposed in the license amendment request.
EFR's responses leave unresolved the following issues regarding radon flux modeling:
1. The dependence of Radon emanation and diffusion coefficient on long-term
moisture content (raised in Item d of INT 12/1) is not but should be addressed.
Please address this dependence. [Note: The Division notes that the radon diffusion
coefficient used in the revised radon emanation analysis for the tailings is higher (by
about a factor of 3) than the diffusion coefficient value assumed in radon emanation
analyses competed for a similar tailings disposal facility (Monticello Tailings
Repository) in Utah (e.g., NRC 2008). The value used in the Monticello analysis was
derived using a different procedure (Rogers and Nielson 1991) than was used by
EFR. Using a higher radon diffusion coefficient in the radon emanation analysis
represents a more conservative assumption.]
2. The summary of values used for long-term moisture content does not adequately
explain the work presented in Attachment H, Attachment C.2. This lack of
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supporting interpretation basis leaves unresolved the conclusion that the values
used in Radon modeling are conservative. Please complete the discussion of values
of long-term moisture content used in Radon modeling.
3. Values summarized in Table C-4 for diffusion coefficients are inconsistent with
those appearing in Attachment H, Attachment C.3. Please resolve this inconsistency
4. All calculated Radon fluxes from the surface of the cover system (Layer 5) exceed
20 pCi/cm^-s, albeit by very slight amounts. Please address the apparent failure of
the proposed cover system design to satisfy the regulatory constraint for Radon flux.
13.0 Concentrations of Radionuclides Other Than Radium
13.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; 10CFR40,
Appendix A, Criterion 6(6); INT 13/1; Concentrations of Radionuclides Other Than
Radium
The interrogatory requested that EFR do the following:
1. Please propose appropriate soil background values (for different geological areas as
needed) for Ra-226, U-nat, Th-230, and/or Th-232, as appropriate, with supporting data.
2. Please indicate whether elevated levels of uranium or thorium are expected to remain in
the soil after the Ra-226 criteria have been met, and if so, describe your use of the radium
benchmark dose approach (Appendix H of NUREG-1620) for developing
decommissioning criteria for these radionuclides.
3. Please provide a description of the instruments and procedures that will be used for soil
background analyses, radium-gamma correlations, and verification data along with
information about the sensitivity of the procedures.
4. Please provide final verification (status survey) procedures to demonstrate compliance
with the soil and stmcture cleanup standards. The procedures should specify instruments,
calibrations, and testing, and the verification soil sampling density should take into
consideration detection limits of samples analyses, the extent of expected contamination,
and limits to the gamma survey. The gamma guideline value should be appropriately
chosen, and the verification soil radium-gamma correlation should be provided along
with the number of verification grids that had additional removal because of excessive
Ra-226 values. The plan should provide for adequate data collection beyond the
excavation boundary. Surface activity measurements should demonstrate acceptable
compliance with surface dose standards for any structures to remain onsite.
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13.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan.5.0 R313-24-4;
10CFR40, Appendix A, Criterion 6(6); INT 13/1; Concentrations of Radionuclides
Other Than Radium
IN TTS RESPONSE, EFR indicated the following-
"The White Mesa Mill reports quarterly composite environmental air particulate data for U-nat,
Th-230, Ra-226 and Ph-210. The results of the environmental air sampling presented in the
Mill's Semi Annual Effiuent Reports show concentrations well below the Mill's ALARA goal of
25% of the regulatory standard for each radionuclide. Each of these four radionuclides were
considered in setting reference soil concentrations for reclamation.
The reference soil concentrations for Ra-226 are set at 5 pCi/g and 15 pCi/gfor the surface 15
cm soil layer and the subsurface 15 cm soil layer, respectively (hereafter referred to as "5/15").
The dose from Ph-210, which due to its short half-life is assumed to he in equilibrium with the
parent Ra-226, was assigned to the dose from Ra-226. (See Attachment I for further discussion.)
The site does not contain thorium byproduct material therefore Ra-228 and Th-232 are not
applicable.
The soil concentration limits for radionuclides other than Ra-226 are derived from doses
calculated for Ra-226 at 5/15 using the same exposure scenarios as were used to estimate the
dose from Ra-226 at 5/15. This is referred to as the radium benchmark dose (RBD). This
approach was used to establish soil concentration limits for U-nat and Th-230.
Based on available data, the preliminary estimate of background for Ra-226 is the average
concentration at the site background location (BHV-3) which is 0.93 pCi/g Ra- 226 as indicated
in Section 6.6 of Attachment A. The 0.93 pCi/g Ra-226 background concentration is close to
nearby measurements from a background program with values of 1.1 pCi/g Ra-226 near the
airport entrance south of Blanding and 0.83 pCi/g Ra-226 southeast of Crescent Junction
(Myrick et. al, 1981). The 32 Utah measurements ranged from 0.53 to 1.9 pCi/g with an average
of 1.3 pCi/g and a standard deviation of 0.74 pCi/g. In addition, Energy Fuels may use site-
specific pre-mill background soil concentrations if this information is available.
Preliminary estimates of background for U-nat and Th-230 are based on the Ra-226
concentration on the assumption of secular equilibrium for natural materials. Therefore, the
predicted U-ndt background is 1.90pCi/g (le., 2.051 times 0.93 pCi/g) with the Th- 230
background concentration set equal to 0.93 pCi/g.
These preliminary estimates of background concentrations are considered suitable for the
scoping survey; however, as recommended in the MARSSIM guidance, a site-specific sampling
program will be conducted prior to final status survey with the locations selected with similar
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geology (surface soil) as the White Mesa areas, in order to determine the background
concentrations to he used for final decommissioning.
Generally, elevation of U-nat and Th-230 concentrations relative to Ra-226 is unexpected since
the contaminated materials will either be ore (which are at or near secular equilibrium) or
tailings where U-nat is reduced relative to the other uranium decay series radionuclides of
interest Possible exceptions are areas with raffinate crystals which may have higher Th-230
concentrations compared to Ra-226 concentrations and areas of spilled yellowcake product near
the Mill where U-nat may be elevated relative to Ra-226.
The RBD approach was applied as described in Attachment L The RESRAD (Version 6.5) code
[Yu et al 2001] was used to implement the RBD approach. The RESRAD code is an accepted
code by the NRC for application of the radium benchmark dose approach as described in
Guidance to the NRC Commission Staff on the Radium Benchmark Dose Approach, a document
included in NUREG-1569 as Appendix E (NRC 2003b). In brief radionuclides at the reference
soil concentration limits result in the same benchmark dose as the allowable Ra-226
concentration.
The concentration limits for the radionuclides of interest were calculated and are provided in
Table 1 for the surface and subsurface layers. The scenario is for a rancher with the doses
determined using the RESRAD Version 6.5 model The default RESRAD dietary and inhalation
data which apply for the adult are carefully selected from literature and are.already considered
to represent conservative parameter values. Details on the calculation of concentration limits
are provided in Attachment I (the SENES letter report on RBD).
Incremental Concentration Limit (pCi/g)
Radionuclide Surface Layer Subsurface Layer
U-nat 545 2908
Th-230 46 142
Ra-226 5^ 75^
a Allowable incremental Ra-226 concentration
Since there is more than one radionuclide, the criteria for unrestricted use is applied using the
unity rule such that the RBD is never exceeded (le., the sum of the ratios for each radionuclide
incremental concentration present to the concentration limit will not exceed "1").
The concentration in the numerator is determined by subtracting the local background from the
total measured value following remediation. It is possible that the background may vary between
survey units due to variation in soil types.
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The sum rules are:
For the surface soil:
A (pCi/g inc. Ra-226) B (jpCi/g inc. U - nat) C (pCi/g inc.Th-230) ^ ^
5 ipCi/g) 545 (pCi/g) 40 (pCi/g) "
For the subsurface soil:
A (pCi/g inc. Ra-226) B (pCi/g inc. U - nat) C (pCi/g inc.Th-230) ^ ^
15 (pCi/g) 2908 (pCi/g) 142 (pCi/g) "
EFR indicated that uranium ores arriving at the mill require very aggressive extraction in the
mill in order to recover uranium. EFR stated that this suggests that the uranium in ores
processed at the Mill is in an insoluble form. Similarly, residual uranium in solids discharged to
the tailings was not extracted through the mill process and can reasonably be assumed to be in
an insoluble form. Thus, EFR concluded that it is reasonable to assume that any incremental (to
background) uranium remaining following remediation is most likely to be in non-soluble forms
and hence, chemical toxicity of uranium, which is dependent on exposure to soluble forms, is not
considered.
EFR stated that gamma radiation surveys will be conducted either with the existing Ludlum-I9
methodology that has been used for operational monitoring as well as previous remediation at
White Mesa, or with a GPS-integrated system using 2 inch by 2 inch sodium iodide (Nal)
detectors or the equivalent Descriptions of the existing Ludlum-19 instrument and standard
operating procedures are provided in the Mill's Radiation Protection Reclamation Manual
Procedures for the GPS-integrated survey will be developed if that approach is to he used.
Statistical correlations will be developed between the sum rule and the gamma radiation
measurements. The sum rule will he determined from measurement data for incremental
concentrations at each sample location. The correlation between the measurement sum rule and
the gamma radiation measurement at the sample location will produce a prediction equation.
MARSSIM requires that the mean concentration in a survey unit be demonstrably lower than
criteria following remediation but does not require all sampling units, in this case the 10 meter
by 10 meter areas, to be lower than the criteria. The precision goal for the relationship will be
that the mean prediction uncertainty for the survey unit will be +/- 0.2 when the predicted sum
rule is equal to "1".
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The selected alpha error will be 0.05. The initial number of samples will be 15 and the
correlations will he assessed following the scoping survey and additional measurement locations
will be added, if necessary, to reach suitable precision. Although, final verification requires that
the mean is statistically below the criterion, the EFR goal will be to remediate each 10 meter by
10 meter block, or sampling unit, so that the predicted sum rule meets the criterion of "1".
The final verification survey will be focused on ensuring that the excavation of remediation areas
has been established.
Gamma Radiation Surveys
Locations within the survey areas where excavation has been performed will have a gamma
radiation scan. Survey procedures with the Ludlum-19 methodology would follow the existing
procedures provided in the Mill's Radiation Protection Reclamation Manual.
With the GPS-integrated methodology, high density gamma radiation scanning surveys can be
done using the un-collimated Ludlum 44-10 detectors at a height of 18 inches above the ground.
Transects are planned to be 5 m apart to facilitate calculation of 10 meter by 10 meter averages,
and this coverage will continue up to 20 meters outside the excavation outline. These locations
would correspond to a Class I classification in the Multi-Agency Radiation Survey and Site
Investigation Manual (MARSSIM NUREG-1575). The remainder of the survey area outside the
remediation area corresponds to Class II in MARSSIM and will be surveyed at planned 10 meter
transects. The gamma radiation coverage goal will be that 95% of the 10 meter by 10 meter
blocks have at least 20 gamma radiation measurements-far blocks in and immediately
surrounding the excavation areas with measurements in at least three of the four quadrants of
the 10 meter by 10 meter block. The requirement for the remainder of the survey area, Class 2,
will be that 95% of the blocks have at least 10 gamma radiation measurements.
The Class 3 area will include the buffer areas outside the area of contamination, and this area
will be surveyed with planned transects of 50 meters. The requirement here is that 20% ofthe 10
meter by 10 meter blocks have at least 10 measurements.
Gamma Radiation Guideline Level
The gamma radiation data will be processed to establish the average gamma radiation count
rate over the 10 meter by 10 meter blocks. A correlation relationship will be established between
the gamma radiation level and the measured sum rule using coincident gamma radiation and
soil concentration measurements. The gamma radiation guideline value will he the value such
that the predicted mean is 0.8 for the correlation relationship defined for the survey area and the
DQO for 10 meter by 10 meter blocks has been attained for gamma radiation. Locations where
the gamma radiation guideline is exceeded will have additional excavation and updated gamma
radiation surveys before confirmatory sampling.
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Selection of Verification Samples
Following completion of excavation, verification sampling will be carried out to meet two
objectives with the first being confirmation of the correlation equation and second, an
independent evaluation of the criteria based on soil samples alone. Locations for the initial
verification sampling will be established based on a combined selection of sampling points using
process history and a random sampling approach for each investigation area. Following a final
status gamma radiation survey, a minimum of 15 blocks in the survey unit will be measured to
confirm the gamma radiation guideline level. For these 15 samples, the five 10 meter by 10
meter blocks with the highest average gamma radiation will be sampled along with another 10
sample blocks randomly selected from the area.
The soil measurements from the 10 randomly selected locations will he assessed to determine if
the mean concentration in the survey unit is statistically below the sum rule with an alpha error
of 0.05 using the MARSSIM Sign test (The Sign test is used because the sum rule involves
incremental above background concentrations.)
However, the statistical test could fail to show that the mean is below the criterion due to the
initial number of verification samples. In this case, the mean and variability ofthe 10 randomly
selected measurements will be used to determine MARSSIM's relative shift with a target grey
error equal to 0.8 of the sum rule. The alpha error will be set to 5% and the beta error set to
10% to determine the required total number of samples. A random sample will he determined for
collection ofthe required number of additional samples.
Revision of Correlation
The verification sample measurements will be compared to the correlation predictions to
determine if the correlation consistently over or under-predicts (le. is biased) the sum rule. The
correlation will be updated with the verification measurements if there is a statistically
significant departure, with a p-value of 0.05, over the range of interest (sum rule from 0.5 to 1.0)
evaluated using the paired difference between the predicted sum rule using the correlation and
the measured sum rule.
Reporting
For each survey area, the following will be reported:
1. Number of blocks remediated during remediation phase.
2. Number of blocks with subsequent remediation initiated by verification gamma radiation
sampling.
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3. Gamma radiation coverage compliance (i.e. percentage of blocks meeting number of
measurement criteria).
4. Mean gamma radiation level averaged over the 10 meter by 10 meter blocks.
5. Mean and range of predicted sum rules based on gamma radiation survey.
6. Mean and range of measured sum rules based on verification sampling.
1. Only clean, uncontaminated buildings, such as office space may remain after
reclamation."
13.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0; R313-24-4; 10CFR40, Appendix A, Criterion 6(6); INT 13/1;
Concentrations of Radionuclides Other Than Radium
To further resolve remaining issues pertaining to concentrations of radionuclides other
than radium in soil, the Division requests that EFR please do the following:
1) Provide justification (either data or references to data) to support EFR's
determination of U-nat and Th-230 background concentrations.
2) Incorporate a description of how EFR's site-specific sampling program will be used
to determine background concentrations for radionuclides other than Ra-226 into
EFR's documentation of how MARSSIM will be implemented and submit for the
Division's review.
3) Incorporate a description of how EFR will use the "sum rules" for surface and
subsurface soils into EFR's documentation of how MARSSIM will be implemented
and submit for the Division's review.
4) Incorporate a description of EFR's plan for using radiation measurement
instrumentation for soil background analyses, radium-gamma correlations,
verification data, and sensitivify analyses into EFR's documentation of how
MARSSIM will be implemented and submit for the Division's review.
5) As suggested in Item 4 of INT 13/1, please incorporate into documentation relating
to how MARSSIM will be implemented, descriptions of the following:
Calibration procedures
^ Instrument testing
Detection limits of sample analyses
^ Extent of expected contamination
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^ Limits of gamma survey
^ Verification of the soil-radium gamma correlation
14.0 Cover Test Section and Test Pad Monitoring Programs
14.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; 10CFR40,
Appendix A; INT 14/1; Cover Test Section and Test Pad Monitoring Programs
The interrogatory requested that EFR do the following:
Refer to Section 8.0 of Attachment A (Technical Specifications and Attachment B (Constmction
Quality Assurance/Quality Control Plan) to the Reclamation Plan and Section 5.0 of Appendix D
(Updated Tailings Cover Design Report) ofthe Reclamation Plan Rev. 5.0 (DUSA 201 la):
1. Please provide plans and specifications for constmcting and performing monitoring and
testing of a cover system section representative of the proposed ET cover system for
verifying the hydraulic performance characteristics of the cover system. Demonstrate that
the proposed test pad/plot will be sufficient in size to eliminate or minimize lateral
boundary effects. Describe objectives and criteria for constmction and testing ofthe test
pad cover materials /layers. Include information in the CQAQC Plan regarding
procedures for sampling and testing of the cover system section specifically pertinent to
demonstrating the (short-term and long-term) performance of the ET cell cover design.
Address, as part of the testing program, testing of parameters specifically recommended
by Benson et al. 2011; Waugh et al. 2008; the National Research Council 2007; Albright
et al. 2007; others) including, but not necessarily limited to:
a. Monitoring of in-situ soil water tension and volumetric water content as a
function of time (e.g., using heat dissipation probes and TDR [time domain
reflectometry]);
b. Monitoring of in-situ flux rates as a function of time (e.g., through use of one or
more pan lysimeters as recommended by Benson et al. 2011 and Dwyer et al.
2007) on both north and south-facing slopes as required);
c. Physical sampling and laboratory testing for index properties, including Plasticity
Index and saturated hydraulic conductivity, and other pertinent parameters
including compaction properties, organic matter and CaC03 content, and
measurement of soil edaphic properties (properties that influence vegetation
establishment and growth - e.g., see Waugh et al. 2008);
d. Other testing if needed for determining changes in water in storage and soil water
characteristic curves (SWCCs, e.g., according to ASTM D6836 [ASTM 2008])
and monitoring for potential changes in SWCCs through time;
e. Conducting soil vegetation surveys (as recommended by Benson et al. 2011); and
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f Monitoring of relevant climatological parameters (precipitation and evaporation
rates, temperature, barometric pressure, snow amounts, wind speed and wind
direction, etc.), including continuous monitoring over several years necessary to
understand how covers are influenced by fluctuations in climate and other ^
environmental factors (Waugh et al. 2008) such as an extraordinarily wet year or
consecutive wet years.
2. Provide additional information and plans and specifications for constmcting and testing a
cover system "test pad/test plot" prior to constmction of the proposed ET cover system
over the consolidated, dewatered tailings. Demonstrate that the proposed test pad/plot
will be sufficient in size to eliminate or minimize lateral boundary effects. Describe
objectives and criteria for constmction and testing of the test pad cover materials /layers
including but not limited to:
a. Acquisition of data of the types described in Item 1. Above;
b. Determination of an acceptable zone (AZ) for soil textures ia soils used for
constmcting the final cover system (e.g., Williams et al. 2010);
c. Determination of most effective means of "bonding" individual soil cover soil
layers (e.g., Dwyer et al. 2007); and
d. Determination of appropriate lift thickness/placement and compaction equipment
combinations (e.g., Dwyer et al. 2007).
14.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan.5.0 R313-24-4;
10CFR40, Appendix A; INT 14/1; Cover Test Section and Test Pad Monitoring
Programs
IN ITS RESPONSE, EFR proposes to use a "performance monitoring section" to evaluate
performance ofthe final tailings cover system. The conceptual design will be adopted from the
installation instructions for the test sections used in the Alternative Cover Assessment Program
(ACAP) (Benson et al, 1999) and will incorporate the performance monitoring
recommendations provided in NUREG/CR-7028 (Benson et al, 2011) and site-specific
recommendations provided by Dr. Craig H. Benson (Craig H. Benson, personal communication,
May 8, 2012). EFR proposes to provide detailed plans, specifications, and a QA/QC plan
following the Division's approval of the proposed performance monitoring [program].
IN ITS RESPONSE, EFR also proposes not to construct or observe performance of a cover
system test pad prior to construction of the final cover system. Instead, EFR argues that
observed performance of the nearby closed Monticello Uranium Mill Tailings Disposal Facility
provides a reasonable basis for inferring performance of the proposed final cover system design.
EFR identifies two additional features ofthe proposed White Mesa design that are not present in
the Monticello design, a biointrusion layer and a sand drainage layer. EFR argues that these
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differences have opposite effects on White Mesa performance relative to Monticello
performance; namely, that the biointrusion layer reduces water storage capacity, while the sand
drainage layer increases water storage capacity. EFR concludes that these projected
performance differences will have opposite and offsetting effects on projected percolation and
that the cover design differences ".. . should results on only marginal differences in hydrologic
performance."
IN ITS RESPONSE, EFR also states in its response that for the White Mesa cover system, it will
maintain a rough surface on all hut the uppermost lift to ensure that interlift zone is as non-
transmissive as practical
IN ITS RESPONSE, EFR also states that it proposes to construct test strips where the lift
thickness and equipment are varied prior to construction [of the fmal cover system]. The
purpose of these test strips is to identify lift thicknesses and equipment that promote uniform soil
compaction without over-compacting the soil, rendering the soil suitable for establishing
vegetation in the cover system.
14.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0; R313-24-4; 10CFR40, Appendix A; INT 14/1; Cover Test Section
and Test Pad Monitoring Programs
The Division has a concern that comparing the performance of the proposed ET cover at
the White Mesa Mill Site to the performance of the Monticello tailings repository cover
system is inappropriate, for several reasons. For example, the cover system at Monticello is
a composite system (having several types of highly-specialized layers designed to
accomplish various physical objectives). More specifically, the cover system at Monticello
differs significantly in design and operation from the currently selected monolithic cover
system proposed for White Mesa in that (1) the Monticello cover system includes an animal
intrusion barrier (consisting of cobbles at about 1 m (~ 3 feet) of depth), and (2) a capillary
barrier (at ~ 1.6 to 2 m, located below the animal intrusion barrier, below another layer of
soil, and just above the radon barrier). Each of these cover system components provide
important functions not accomplished in the currently-proposed monolithic soil ET cover
design for White Mesa.
In addition to differences in design between the Monticello repository cover and the
proposed ET cover for the White Mesa Site, there are fundamental differences in the
properties of the soils used to construct the Monticello cover compared to the soils
currently proposed for use in constructing the ET cover at White Mesa. For instance, soils
proposed by EFR for use in constructing the ET cover are extremely low in natural organic
matter (OM) content, e.g., compared to soils that were used for constructing the Monticello
Tailings Repository cover system e.g., zero to about 0.4 % according to Table D-5 in
Appendix D of the Revised ICTM Report, compared to a recommended minimum OM
content of from approximately 1.5 to 3.0%). These factors indicate that, given the natural
climate conditions at the site (which could include possible prolonged (e.g., decadal to
multi-decadal) future drought periods likely to create conditions unfavorable for sustaining
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plant growth in the cover), and without substantial and extensive OM enhancements
incorporated into the soils prior to cover construction and possible periodic active post-
closure intervention/maintenance measures such as reseeding, possible irrigation of the
cover, etc., the on-site soils tested to date appear to be unfavorable for.use in constructing
the ET cover (see also discussion in Section 2.3.1 of the Technical Memorandum, White
Mesa Mill Site - Revised ICTM Report Review addressing EFR's Response to Rd 1
Interrogatory 02/1 on the Revised Infiltration and Contaminant Transport Modeling
Report).
The Division also notes the following statements made by EFR in in the Revised ICTM
Report (Denison Mines 2010):
• On Page 4-2 in the Revised ICTM Report (Denison 2010), EFR states
"Furthermore, results from nearby uranium mill tailings lysimeter at Monticello
(Waugh et al., 2008) also agree with model predictions for the proposed cover
system at White Mesa." The Revised ICTM Report proceeds to compare modeled
infiltration rates at the proposed cover at White Mesa with measured infiltration
rates associated with the Monticello cover.
• On Page 4-2 in the Revised ICTM Report (Denison 2010), EFR also states " The
model-predicted infiltration rates for monolithic ET cover are consistent with data
reported from lysimeter and infiltration modeling studies of other vegetated ET
covers (e.g., Albright et al. 2004; Bolen et al. 2001; Fayer and Gee 2006; Gee et al.,
1994; Scanlon et al. 2005).
After referring to studies by Bolen et al. (2001), Albright et al. (2004), and others
mentioned, the Revised ICTM Report states, "In summary, a monolithic ET cover is the
preferred design to minimize infiltration necessary to meet the Permit (Part I.D.8) and
meet the radon attenuation standard." However, the cover systems described in several of
these cited references contain different design components, such as a capillary break, that
are not included in the currently proposed ET cover. For example, Bolen et al. 2001 review
ET cover systems at 12 sites. Unlike the proposed White Mesa cover system, a number of
the 12 cover systems reviewed by Bolen et al. (2001) are reported to contain either a sand
layer or a gravel layer of appreciable thickness, which may act as a capillary barrier/
capillary break. Albright et al. 2004, who discuss the same 12 sites, state that six of them
have a capillary barrier/break layer. Also unlike the proposed cover system at White Mesa,
however, nearly all (i.e., 10 of 12) of these sites have geosynthetic root barriers consisting of
nonwoven geotextile containing lumps of slow-release trifluralin (herbicide-like plant root
inhibitor) (see also Albright et al., 2004). Each barrier is installed between interim cover
and the overlying final cover system. Trifluralin acts to prevent plant biointrusion into
waste by interfering with root mitosis so that its use at a site can modify impacts of rooting,
biointrusion and drainage through a cover system.
The other studies mentioned by EFR also refer to sites with cover systems having
substantial differences from the proposed White Mesa site cover system. Fayer and Gee
(2006), for example, describe performance of four fypes ET cover systems at the Hanford
Lysimeter Test Facility at a semi-arid site in Hanford, Washington for periods of up to 17
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years. Of interest here is that each type of cover system described incorporates a capillary
barrier/break layer, as part of the "Hanford Barrier", in some form.
The cover design for the Crescent Junction, Utah tailings repository (relocation repository
facility for the Moab tailings) also contains a combination "Infiltration and Biointrusion"
Barrier" underlying the frost protection component of the cover and overlying the radon
barrier layer in the cover (see, e.g., DOE 2012, Addendum E, p. 14).
Several published studies demonstrate that incorporating a capillary barrier (with an
adjacent granular filter layer) can substantially reduce cover infiltration rates. For
example, a comparison of two otherwise similar cover systems (one monolithic with a thick
soil cover, and one non-monolithic, with a capillary barrier) in terms of their ability to
restrict drainage shows that the cover system with a thick soil cover was outperformed by
the cover system having a capillary barrier by up to a ten-to-one ratio or greater (Porro
2001). Similar results were obtained in forced irrigation testing of alternative cover systems
by Martian et al. 2001. Infiltration reduction depends on cover-system materials and
environmental conditions. Hydraulic performance is evaluated as the probability that ET
from the water-storage soil layer overlying the capillary break layer is sufficient to prevent
water accumulation in the soil sponge layer from exceeding its storage capacity in any given
year. The potential benefits in cover system infiltration performance with a capillary
barrier are well documented.
For reasons described above, the Division also finds that the technical adequacy of a
monolithic ET cover at the White Mesa site is not adequately supported by the
comparisons EFR provides to other cover systems as described in technical references cited
by EFR.
With respect to a Test Pad/Test Section, the Division believes that there is value in, and a
need for, constructing and monitoring a pilot test pad or pilot test section prior to full-scale
cover construction, and in a location off of the tailings. Information and benefits that can
be gained from such pilot testing include:
• Helps establish/verify a performance standard for the cover;
• Validates the cover design and construction;
• Could resiilt in suggestions for improved design features and construction methods
when implementing the full-scale cover construction; and
• Helps to identify and resolve problems that may be encountered during full-scale
cover construction, e.g., allow engineers to evaluate, plan for, and/or mitigate
factors such as vegetation establishment (in)effectiyeness and address issues such as
loss of one or more planted species following seeding/vegetation placement,
desiccation cracking during or following cover layer placement and compaction;
etc., and
• Provides monitoring data (e.g., from field-scale pan lysimeters) to help evaluate the
future infiltration performance of a full-scale cover constructed to a similar set of
standards and using the same construction equipment and construction methods, as
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well as reduces risks associated with potential failure of, or disruption of in-situ
cover conditions resulting from emplacement of, one or more monitoring devices
installed within the full-scale cover system.
Advance construction and testing of such a Test Pad or Cover Test Section would allow
engineers to obtain data on key characteristics of the constructed cover soils that are
important for vegetation establishment such as soil nutrients, propagules, and
microorganisms (e.g., mycorrhizae) needed to establish a sustainable plant community.
Data collected on concentrations of soil macronutrients (e.g., nitrogen, phosphorus, and
potassium) and micronutrients (e.g., sulfate, zinc, iron, manganese, copper, calcium,
magnesium, sodium, and boron) in the constructed test cover could be used to assess
whether they are similar to and within typical ranges for soils around the site which have
been selected for use as a natural analog or analogs for predicting the final cover vegetation
characteristics and performance.
The sustainability of the ET cover may rely, in part, on the establishment and resilience of
a diverse plant community; however, the dynamics of such a plant community are
complicated and effects are difficult to predict (e.g., Waugh et al. 2008). Link et al. 1994
indicate that, even in the absence of large-scale disturbances, seasonal and yearly
variability in precipitation and temperature will cause changes in species abundance,
diversity, biomass production, and soil water extraction rates on covers. Poor shrub
establishment, for example, could result in poor water extraction, causing water
accumulation in the lower portions of the cover profile during exceptionally wet
precipitation periods (percolation exceeding the total storage capacity or drained upper
limit of the soils). Data on soil structure development observed to occur over time within a
constructed test cover profile following its construction could also be acquired and
compared to that observed in natural soils at the selected analog site(s) to assess conditions
that could be expected to develop in the future full-scale cover with respect to whether they
may be suitable for promoting future development and sustainability of such shrubs, if
desired based on the cover infiltration modeling results.
On the basis of the considerations discussed above, the Division requests the following:
• EFR will need to provide a detailed Technical Work Plan for Division review and
approval, no later than 90 days after approval of the revised Infiltration and
Contaminant Transport Modeling (ICTM) Report by the Division, for constructing,
monitoring and testing a Cover Test Pad//Test Section representative of the
intended full-scale cover system. The Work Plan shall: (1) provide a construction
schedule; (2) provide details ofthe proposed Test Pad/Section's design and
construction; (3) describe the proposed monitoring/testing program duration; (4)
define parameters to be monitored/tested in the Test Pad/Test Section; (5) provide a
schedule and details regarding reporting of monitoring and testing results; (6)
describe objectives of the Test Pad/Test Section construction, monitoring, and
testing program; and (7) propose and justify criteria for demonstrating that those
objectives have been achieved.
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• The Test Pad/Test Section Work Plan will need to address acquisition of data for
parameters (e.g., percolation data, weather data, fertilization and nutrient content
data and other soil testing, botanical data,...) to validate assumptions and
predictions made by EFR with regard to the projected site-specific and cover-
specific performance of the full-scale cover, including future emergence rates and
characteristics of vegetation on the cover.
• The Reclamation Plan should be revised to incorporate the information and
requirements described herein with regard to this Test Pad/Test Section.
EFR's proposal to maintain a rough surface on all but the uppermost lift in the cover is
acceptable and EFR should incorporate this commitment into Attachment A of the next
revision of the Reclamation Plan.
15.0 Financial Surety Arrangements
15.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-24-4; 10CFR40,
Appendix A, Criterion 9; INT 15/1; Financial Surety Arrangements
The interrogatory requested that EFR do the following:
1. Justify the decrease in costs estimated for mill decommissioning and reclamation of Cells 1,
2, and 3 firom those estimated in the White Mesa Reclamation Plan, Rev. 4.0 dated
November 2009. Explain why several estimated levels of effort (e.g., total effort for Mill
Yard Decontamination, Ore Storage Pad Decontamination, Equipment Storage Area Cleanup
and Cell 1 Constmct Channel) are smaller in 2011 than those estimated in 2009. Explain and
rectify apparent discrepancies between labor rates used in cost estimates and those presented
in the exhibit in Attachment C titled "Labor Costs".
2. Identify analytes for which soil samples identified in the cost estimate for "Cleanup of
Windblown Contamination" will be analyzed. Justify (or revise with justification) the
assumed sample analysis cost of $50.
3. Revise and report estimated reclamation costs, incorporating responses to instmctions listed
above.
4. Estimate and report the costs for a third party to conduct decommissioning and impoundment
reclamation in the coming year rather than at the end of plaimed life.
5. Please provide and justify estimates of costs associated with complying with the current Air
Quality Approval Order (DAQE-ANl205005-06, issue date July 20, 2006) and License
Condition 11.4 and 11.5 during final reclamation, as stated in Section 1.5 of Reclamation
Plan 5.0, Attachment A, Technical Plans and Specifications.
6. Please state and justify the times projected to be necessary to dewater Cell 2 and Cell 3.
Provide and justify estimates of all costs associated with the apparently lengthy dewatering
time for Cell 2 and Cell 3 (Also see Interrogatory 7/01, item 8).
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15.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan_5.0 R313-24-4;
10CFR40, APPENDIX A, CRITERION 9; INT 15/1; Financial Surety
Arrangements
IN ITS RESPONSE, EFR committed to answering quantitatively all aspects addressed in the
interrogatory only after the cover design is "conceptually approved". EFR also indicated that:
(l)Costs for complying with the Air Quality Approval Order and current license condition, and
costs for dewatering of Cells 2 and 3 are incidental to the daily operation at the White Mesa Mill
and are covered in the Miscellaneous section of the Reclamation Cost Estimate; (2) The current
cost estimate for dewatering of Cells 2 and 3 includes the construction and operation of a
holding pondfor solution from the dewatering of the tailings cells; and (3) O&M costs for the
dewatering of Cells 2 and 3 will be re-evaluated once the final cover design is conceptual
approved.
15.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0; R313-24-4; 10CFR40, Appendix A, Criterion 9; INT 15/1;
Financial Surety Arrangements
EFR must submit and receive approval of its revised cost estimates before the Division will
approve EFR's proposed and revised cover system design.
EFR has inadequately addressed the time required to dewater Cell 2 and Cell 3 prior to
final cover construction, EFR should submit technically supported quantitative projections
of the times required to achieve moisture contents for these cells upon which the final
covers can be constructed with expectation that the dewatered tailings will not likely
contribute to instabilities in the covers. These quantitative analyses should consider all
mechanisms that affect water content of the tailings, including (but not limited to)
precipitation, runoff, infiltration, lateral drainage, transpiration, evaporation, percolation,
groundwater migration, and active removal. Quantitative analyses shopld also include
uncertainfy and sensitivify analyses to account for known and likely uncertainties in input
parameter values and their effects on dewatering. The Reclamation Plan must include a
detailed description of dewatering measures that EFR will use to accomplish dewatering of
Cells 2 and 3 within the 7 year-time period specified in the latest Financial Surefy
submitted to the Division by EFR (See also Section 7.3 above). The current Surefy
submittal of March 14,2012 (including the revised submittal dated September 14,2012)
does not list the time to dewater Cell 2. However, all other cells show a 62,400 hour
dewatering time). Costs of the specific dewatering measures need to be included in the
Financial Surefy. Because this revised evaluation and the revised reclamation cost
estimates described above were not submitted with EFR's response to the Rd 1
interrogatories, this issue will remain open.
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16.0 Radiation Protection Manual
16.1 Round 1 Interrogatory White Mesa RecPlan REV 5.0 R313-15-501; 16/1: Radiation
Protection Manual
The interrogatory requested that EFR do the following:
Refer to Appendix D, Radiation Protection Manual for Reclamation:
Provide information on how these largely operational radiation protection practices will change
to support the changed needs of decommissioning and reclamation. Describe how the Radiation
Protection program will be evaluated and revised to address the range of activities required to
support decommissioning and reclamation activities. The following are selected examples of
topics (not exhaustive) that should be evaluated and possibly revised to support
decommissioning and reclamation.
• Section 1.3 Beta Gamma Surveys: Conduct beta gamma frisk surveys where appropriate
during decommissioning and reclamation.
• Section 1.4 Urinalysis Surveys: State the frequency of conducting urinalyses during
decommissioning and reclamation.
• Sections 2.1.2,2.3.2,2.4.2 Frequency/locations: State how the frequency and locations
for all monitoring methods will be modified to accommodate decommissioning and
reclamation activities.
16.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan.5.0 R313-15-501 INT
16/1; Radiation Protection Manual
IN ITS RESPONSE, EFR indicated the Radiation Protection Manual (RPM) for Reclamation has
been updated (Revision DUSA-2 dated 05/12) to include practices for decommissioning and
reclamation. The updated manual begins to address some of the changes that will be necessary
once the mill transitions from operations to decommissioning and reclamation. However the
document is still generally focused on operations and does not address how the program will he
modified to address the unique decommissioning requirements, or the process through which the
manual and program will be revised in the future.
Based on the RPM as provided in the response, during decommissioning the contamination
control surveys that are required in Section 2.6.3 of the decommissioning plan will he limited to
surveys for alpha contamination, similarly the "Radiation Survey of Equipment Released for
Unrestricted Use ", will he limited to surveying equipment for fixed and removable alpha
contamination and beta gamma dose rates. The updated RPM gives the RSO the ability to
remove areas from the routine survey list but does not indicate how areas established during
decommissioning may be added if appropriate, to the routine survey list. The RPM does not
include the procedures for gamma radiation surveys that are discussed in the response
document.
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16.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0; R313-15-501; INT 16/1; Radiation Protection Manual
The Division requests that EFR revise the RPM to specify how the program will be
modified to address the unique decommissioning requirements, or the process through
which the manual and program will be revised in the future. EFR should also include
procedures for gamma radiation surveys in the revised RPM that are discussed in the
response document. Because this revised information was not submitted with the response,
this interrogatory will remain open.
17.0 Response to Int White Mesa Recplan Rev 5.0 R313-15-1002; INT 17/1;
Release Surveys
17.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-15-1002; INT 17/1;
Release Surveys
The interrogatory requested that EFR do the following:
Refer to Attachment D, Section 2.6, Release Surveys:
Revise to address the decontamination, release, and disposal of equipment and buildings
necessary to support decommissioning and reclamation. Develop and present detailed release
survey procedures and identify appropriate radiation survey equipment that will be used.
Develop and present additional decontamination procedures during decommissioning and
reclamation and include section on disposal of equipment that cannot be decontaminated.
17.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan 5.0 Rev 5.0 R313-15-
1002; INT 17/1; Release Surveys
IN ITS RESPONSE, EFR provided reasonable procedures for alpha and beta-gamma surveys.
The selection of equipment is judged appropriate on the strength of the Division's previous
reviews and acceptance of the Radiation Protection Manual for Reclamation. EFR has, however,
inadequately addressed the Division's requests for additional information regarding
decontamination, release, and disposal of equipment and buildings during decommissioning and
Reclamation.
17.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0 R313-15-1002; INT 17/1; Release Surveys
EFR should yet either (1) cite previously submitted documents where these topics were
addressed or (2) develop and submit for the Division's review and approval the following:
• Decontamination procedures for buildings and equipment.
• Disposal of building components and equipment either on-site or off-site, depending
on results of release surveys.
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
18.0 Response to Int White Mesa Recplan Rev 5.0 R313-12; INT 18/1, Inspection
and Quality Assurance
18.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 5.0 R313-12; INT 18/1;
Inspection and Quality Assurance
The interrogatory requested that EFR do the following:
Refer to Attachment A, Plans and Technical Specifications, Section 1.6, Inspection and Quality
Assurance: Revise the provided the "Radiation Protection Manual for Reclamation" cited in this
section, to define the responsibilities and duties of the Radiation Safety Officer.
Refer to Attachment A, Plans and Technical Specifications, Section 1.8b, Inspection and Quality
Assurance: Revise the wording to indicate that the DRC must review and approve all design
modifications to the Reclamation Plan.
18.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rey.5.0 R313-12; INT
18/1; Inspection and Quality Assurance
IN ITS RESPONSE, EFR indicated the following:
Section 1 of the Radiation Protection Manual for Reclamation (Attachment D of the Reclamation
Plan, Revision 5.0) has been revised to include the responsibilities of the Radiation Safety
Officer during reclamation (see Attachment E to the May 31, 2012 response document); and
The wording in section 1.8b of the Technical Specifications will be revised to indicate the DRC
must review and approve all design modifications to the Reclamation Plan.
18.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0 5.0 R313-12; INT 18/1; Inspection and Quality Assurance
EFR has inadequately defined the responsibilities and duties of the Radiation Safefy
Officer in its revision of the Radiation Protection Manual for Reclamation.
EFR has committed to, but must yet revise Section 1.8b ofthe Technical Specifications to
indicate that the Division must review and approve all reclamation plan design
modifications.
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TECHNICAL MEMORANDUM
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19.0 Response to Int White Mesa Recplan Rev 5.0 R313-24; 10CFR4.42(J); INT
19/1, Regulatory Guidance
19.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24; lOCFR 40.42(J); INT
19/1; Regulatory Guidance
The interrogatory requested that EFR do the following:
Refer to Attachment A, Plans and Specifications, Sections 6.4 Guidance:
Please revise the decommissioning plan to reference and incorporate current guidance, namely
NUREG-1757 "Consolidated Decommissioning Guidance"; NUREG-1575 "Multi-Agency
Radiation Survey and Site Investigation Manual (MARSSIM)"; and NUREG-1575 Supplement 1
"Multi-agency Radiation Survey and Assessment of Materials and Equipment Manual
(MARSAME)".
19.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan.5.0 R313-24; lOCFR
40.42(J); INT 19/1; Regulatory Guidance
IN ITS RESPONSE, EFR committed to, but must yet revise the Reclamation Plan to reference
and incorporate guidance provided in the following documents:
• "Consolidated Decommissioning Guidance ", NUREG-175 7
• "Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) ", NUREG-1575
•, "Multi-Agency Radiation Survey and Assessment of Materials and Equipment
(MARSAME) ", NUREG-1575, Supplement 1
19.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0 R313-24; lOCFR 40.42(J); INT 19/1; Regulatory Guidance
Beyond EFR's commitment to revise the Reclamation Plan to reference and incorporate
guidance, EFR must yet actually revise the document and submit it for the Division's
review and approval.
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
20.0 Response to INT WHITE MESA RECPLAN REV 5.0 R313-24; 10CFR40,
Appendix A, Criterion 6(6); INT 20/1, Scoping, Characterization, and Final
Surveys
20.1 Round 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24; 10CFR40
Appendix A Criterion 6(6); INT 0/1; Scoping. Characterization, and Final Surveys
The interrogatory requested that EFR do the follov^ng:
1. Refer to Attachment A, Plans and Specifications, Sections 6.6 Scoping Surveys & Figure
A-1: Provide a figure identifying the areas and survey grid sizes. Clarify how use ofthe
large grids and the spacing shown in Figure A-1 will ensure compliance with the 100
square meter criteria. Explain how samples will be collected from these larger grids.
2. Refer to Attachment A, Plans and Technical Specifications, Sections 6.6 Scoping
Surveys: Provide details (including information on instrument sensitivity) on the beta
gamma radiation instmments that will be used for the scoping surveys. Indicate the
frequency of calibration checks, daily operational checks, and other QA/QC requirements
for the instmments. Also indicate whether these same instruments (used during facility
operations) will be used for subsequent characterization, remediation, and final survey
work.
3. Refer to Attachment A, Plans and Technical Specifications, Sections 6.6 Scoping Surveys:
Explain how areas contaminated with radiurn, thorium, and uranium will be identified
and surveyed to ensure they will not result in a dose that is greater than the radium
standard alone.
4. Refer to Attachment A, Plans and Technical Specifications, Sections 6.6 Scoping Surveys:
Identify what types of samples (e.g., grab or composite samples) will be collected to
support developing the gamma correlation. Explain how locations for taking these
samples will be selected. State how many correlations will be developed and how they
will differ from each other.
5. Refer to Attachment A, Plans and Technical Specifications, Sections 6.6 Scoping Surveys:
Identify the analytes including radioisotopes for which samples will be analyzed by
chemical analysis and identify the preferred analytical method.
6. Refer to Attachment A, Plans and Technical Specifications, Sections 6.6 Scoping Surveys:
Provide information on how other materials that may be left will be identified during
scoping surveys. Identify additional survey procedures for alpha beta and gamma surface
surveys as appropriate.
7. Refer to Attachment A, Plans and Technical Specifications, Sections 6.7 Characterization
and Remediation Control Surveys: Explain how many and how samples will be collected
to ensure the correlation developed for the scoping is consistent with the characterization
and reclamation surveys. Explain how the correlation will be modified to address gamma
variations that may arise during decommissioning and reclamation?
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
8. Refer to Attachment A, Plans and Technical Specifications, Sections 6.8 Final Survey,
Figure A-2 and Attachment B Construction QA/QC Plan, Section 5.4.1: Please clarify the
terminology used in the two documents. Ensure that the activities described are
consistent. Provide details on how the 10% of locations are selected for sampling.
Demonstrate that collection of four samples as shown on Figure A-2 is sufficiently
representative of the entire 100-square-meter area. Explain whether samples taken from
the four sample locations identified in Figure A-2 will be analyzed separately or will be
composited.
9. Refer to Attachment A, Plans and Technical Specifications, Sections 6.8 Final Survey,
Figure A-2: Explain how the areas where final survey soil sample results exceed the
criteria will be addressed. State the basis for determining whether additional removal will
be required. A soil sample that exceeds the criteria may also indicate a problem with the
gamma correlation. Since the majority of the area will be released based on the gamma
correlation, explain how the gamma correlation will be reviewed to ensure the use ofthe
correlation in place of sampling is still valid.
20.2 EFR Responses to Rd 1 Interrogatory White Mesa RecPlan Rev 5.0 R313-24;
10CFR40 Appendix A Criterion 6(6); INT 20/1; Scoping. Characterization, and
Final Surveys
IN ITS RESPONSE, EFR indicated the following:
r
"Usingprocess knowledge and site history. Energy Fuels Resources (EFR) will identify areas of
the site where the type of contamination is generally homogeneous (that is a comparable
contaminant signature) and the geology is similar. At this time, EFR expects delineate nvo areas:
tailings and an associated windblown area, and ore storage area and an associated windblown
area.
Each area within the restricted area has been divided into sub-areas of size 30 meter by 30
meters for the scoping gamma radiation survey. Contamination is probable in these sub-areas
and, following remediation, they would correspond to Class 1 or Class 2 MARSSIM areas. The
gamma radiation survey plan shown in Figure A.l has been revised and is attached as the
Revised Figure A.l. The 30 meter by 30 meter area will cover each of the 10 m cells (blocks in
the drawing) within each survey sub-area.
Effectively, a pattern of three transects per 30 meters provides coverage at the 10 meter by 10
meter area, and this is suitable for the scoping survey. If any measurement within the 30 meter
by 30 meter area exceeds the action limit, a more detailed survey will be conducted within the 10
meter by 10 meter block(s) which exceeded the action limit.
Areas where wind-blown contamination may be present will be divided into similar subareas and
the survey will continue outward from the restricted area until a buffer area of gamma radiation
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
radioactivity below the sum rule limit has been established. This will bound the area for
remediation and final status surveys.
Alternatively, gamma radiation scanning using the GPS-integrated system will be conducted
with a similar density as used in the Ludlum-19 methodology during the scoping surveys. As
before, if any measurement exceeds the action limit, a more detailed survey will be conducted
locally.
The scanning gamma radiation levels from the scoping survey will be used to assist in selecting
locations for sample collection to develop the initial scoping level prediction correlation.
Locations where the sum rule is expected to he 0.5, 1 and 2 (corresponding to incremental Ra-
226 concentrations of 2.5, 5 and 10 pCi/g) will be selected, based on historic knowledge and
field observations, to accurately reflect the relationship near the decision point In addition,
locations with higher concentrations, or areas where substantial disequilibrium is anticipated,
will be sampled.
Gamma radiation surveys will be conducted either with the existing Ludlum-19 methodology that
has been used for previous remediation at White Mesa or with a GPS integrated system using 2
inch by 2 inch sodium iodide (Nal) detectors, or the equivalent.
As indicated in the Mill's Radiation Protection Reclamation Manual each existing instrument
(Ludlum 19) used will be calibrated by an off-site 3rd party, every 6 months.
Daily function checks will be conducted and documented each morning before use. This
information will be housed in the Radiation Department. A function check is also performed
once the instruments return from calibration. This function check is documented, and the daily
checks are compared against this initial function check. If the daily checks are off by more than
^10%, the instrument is considered no longer reliable and must be sent in for calibration. All
function checks are performed using a Cs-137 check source, similar to the 3rd party calibration
laboratory.
The gamma radiation detectors to be used for the integrated-GPS methodology would be 2 inch
by 2 inch sodium iodide detectors (e.g. Ludlum 44-10 or equivalent) with a ratemeter (e.g.
Ludlum 2221 or equivalent) equipped with RS-232 export. The data is exported to a GPS data
logger for availability for mapping and survey interpretation.
These detectors are sensitive to environmental gamma radiation levels and typically provide
suitable precision for gamma radiation correlations below a level of 5 pCi/g.
Similar procedures to those currently used with the EFR Ludlum-19 methodology would be
developed, including for example, calibration and daily checks, if the GPS-integrated
methodology approach is selected,
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TECHNICAL MEMORANDUM
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A gamma radiation level that provides confidence that the sum rule is less than unity for the
survey unit will be established. This will be derivedfrom the correlation between gamn^a
radiation and the sum rule from measurement data collected during the scoping survey. The
gamma radiation survey data will be analyzed to determine the extent of contamination
requiring remediation in each area based on this correlation.
Soil samples collected during the scoping survey will be grab samples from locations determined
based on institutional knowledge and site history to ensure spatial coverage, homogeneous areas
relative to contamination type and geology and the range of gamma radiation levels recorded in
the scoping gamma radiation survey. At each sampling location, a static gamma radiation
measurement over a one minute duration will he recorded with the same instrumentation and
height above the soil as used in the scanning surveys. Based on experience, the incremental
gamma radiation corresponding to 5.0pCi/g Ra-226 is approximately 5,800 cpm for an un-
collimated 2 inch Nal detector. Selection of sample locations will ensure that locations
corresponding to incremental concentrations of 2.5, 5 and 10 pCi/g are selected to optimize the
prediction uncertainty at the 5 pCi/g Ra-226 incremental concentration.
Correlations between the sum rule and gamma radiation will be developed with potentially
different relationships depending on the area. It is expected that the relationships will generally
not be dependent on the mixture of radionuclides in each area. Most of the incremental gamma
radiation is likely to he associated with Ra-226. Unatand Th-230 are weak gamma radiation
emitters compared to Ra-226; however, expectations are that these concentrations are equal to
or less than the Ra-226 concentrations. For example, ore will have these radionuclides generally
in equilibrium and tailings will be depleted in uranium relative to Ra-226. However, there may
be small areas with elevated Th-230 due to specific process wastes (e.g. raffinate crystals).
Differences in the relationship may be more dependent on variations in background due
potentially to different geology. The correlations will be evaluated for the differences that
depend on the area and the amount ofprecision (scatter of actual sum rule versus predicted sum
rule). The target (two sigma) absolute uncertainty for mean predictions of the sum rule will be
0.2 at the decision point where the sum rule equals one; that is, the 95% confidence intervals
when the mean prediction equals "1" will be 0.80 to 1.2 for the sum rule.
Soil samples will be analyzed using methods with minimum detection limit (MDL) that is no
greater than 10% of the concentration limit developedfrom the radium benchmark approach.
The current methods used by the laboratories utilized by EFR are shown in Table 1 and all meet
the MDL objective noted above. The analytes and methodology are given in the following Table
1.
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
Table 1 Analytical Methods and Method Detection Limits
Radionuclide Method RBD Benchmark MDL
Ra-226 E903.0 5pCi/g 0.2pCi/g
U-nat SW6020 Standard RL 545pCi/g O.OlpCi/g
Th-230 E908.0 46pCi/g 0.2pCi/g
With respect to remediation of non-radiological hazardous constituents, NRC guidance in
NUREG-1620, Section 5.2.2 states:
"The decommissioning plan must address the non-radiological hazardous constituents ofthe
byproduct material according to 10 CFR 40 Appendix A Criterion 6(7). For windblown tailings
areas, meeting the surface Ra-226 standard should be adequate to control these constituents in
soil A tailings cell cover that meets Appendix A criteria should control minimize, or eliminate
post closure escape of non-radiological constituents into surface water and the atmosphere.
However any unusual or extenuating circumstances related to such constituents should be
discussed in the reclamation plan or decommissioning plan in relation to protection of public
health and the environment and should be evaluated by the staff. "
EFR has reviewed the history of Mill operations and has identified the following two incidents
which may be considered to have generated "unusual or extenuating circumstances " with
respect to reclamation.
Ammonium Sulfate Tank Area
In response to a Stipulated Consent Agreement between EFR and the Director ofthe Utah
Division of Radiation Control ("DRC"), EFR performed Phase I of a Nitrate Contamination
Investigation described in a May 6, 2011 Investigation Plan approved by DRC The Phase I
investigation identified soil contamination near the Mill's ammonium sulfate storage tanks,
specifically ammonia as N, and nitrate plus nitrate as N, which DRC attributed to spillage from
storage and handling of ammonium sulfate process reagent Because the attributed source ofthe
contamination is not associated with ores or other sources of radiological contamination, EFR
considers this area to represent an unusual circumstance in which non-radiological
contamination may not be captured by excavation to the Ra-226 standard. EFR plans to
remediate this contamination consistent with agreements existing or currently under review by
DRC, as described below.
EFR entered a revised Stipulated Consent Agreement ("revised SCA ") with DRC on September
30, 2011. Pursuant to the revised SCA, EFR submitted a revised Corrective Action Plan
("CAP ") which, among other commitments, required that EFR:
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
• determine the physical extent of the soil contamination observed at the ammonium sulfate,
including an estimate of the volume of the contaminated soils down to but not including
bedrock, and an estimate of the surface area at or above the estimated location ofthe
contaminated soil volume;
• cover the Contaminated Surface Area with at least six inches of concrete, to the extent not
already covered by concrete or existing buildings, and remove the Contaminated Soil
Volume and dispose of the contaminated soils in the Mill's tailings impoundments prior to
site closeout.
The following process will be used to estimate the volume of contaminated soil to be removed
during reclamation. Once the total area to be covered by concrete has been determined based on
the borehole analyses, the area will be multiplied by the average depth to bedrock, as
determined from the logging of the boreholes.
Based on the geologic logging performed during the soil probe sampling in the Phase I
Investigation in June, 2011, borings number GP-25B and GP-26B in the vicinity ofthe
ammonium sulfate tanks indicated depth to bedrock of 19 feet and 16 feel respectively.
These values will be included, along with depths determined during the additional Geoprobe
sampling to develop an average depth to bedrock. This average depth to bedrock will be
multiplied by the area of contamination.
The revised CAP and resulting Consent Order is currently undergoing public review and
comment Following public comment andfinalization of the CAP and Consent Order, EFR will
characterize the areal extent of contamination consistent with the schedule in the revised CAP,
and, at the time of Mill reclamation, excavate the contaminated soils associated with the
ammonium sulfate storage area consistent with the requirements of the CAP and Consent Order.
Claricone Failure and Removal Action
The Mill experienced a spill from the failure of a partially below-grade clarifier (the
"Claricone ") on April 12, 2012. The spilled contents of the Claricone were expected to consist
of an estimated 28,000 gallons of in-process solutions containing approximately 190 lbs of
natural uranium and approximately 3,370 lbs of sulfuric acid.
During April 2012 contaminated soil was removed and disposed in Cell 3 as follows:
a. All soils visibly wet, stained or discolored were excavated until uncontaminated dry
background soils remained.
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TECHNICAL MEMORANDUM
WHITE MESA MILLSITE - REV 5.0 RECLAMATION PLAN REVIEW
b. The bottom and sides of the excavation were scanned by microR meter. When the bottom or
sides ofthe excavation indicated gamma levels greater than background levels, the
excavation was resumed, additional contaminated soil was removed, and the bottom and
sides ofthe excavation were re-scanned until all surfaces resulted in gamma levels less than
or equal to cleanup background. (Cleanup background was defined as two times the average
of four measured background readings. This approach accounted for the contribution to
background of gamma radiation from other nearby process equipment such as the clarifier,
thickener, and CCD impounds.) When the bottom and sides of the excavation indicated
gamma levels of less than cleanup background as defined above, the excavation was
considered complete, and the area was prepared for bacPfill and re-grading.
EFR considered that the excavation, as conducted based on residual gamma screening was
sufficient to ensure that all radiological and non-radiological constituents associated with the
spill had been addressed. However, DRC advised EFR in a letter dated August 8, 2012 that
because confirmation sampling was not conducted subsequent to soil removal DRC required
that EFR provide additional measures to ensure all contamination has been removed. EFR has
proposed to provide a conservative overestimate of contaminated soils to be excavated at the
time of reclamation. EFR will provide a report to DRC describing andjustifying the estimated
excavation volume.
Following approval of the report, and at the time of reclamation, EFR will excavate soil in the
former Claricone area consistent with the approved Excavation Proposal
The correlations are anticipated to remain the same during the program provided that the
vertical gradient of incremental Ra-226 remains similar and that there are not variations in
background encountered. Soils after excavation may have higher or lower concentrations than
the established background due to differences in soil type. Soil samples will be collected during
the verification and these will ensure the relationship is appropriate. These samples may initiate
further excavation if the correlation is revised.
Locations for final verification will be established based on a combined selection of sampling
points using process history and a random sampling approach for each investigation area.
Following a final status gamma radiation survey, a minimum of 15 blocks in the survey area will
be measured to confirm the gamma radiation guideline level For these 15 samples, the five 10
meter by 10 meter blocks with the highest average gamma radiation will he sampled along with
another 10 sample blocks randomly selected from the area. This will allow inspection ofthe
highest gamma radiation blocks (which are more likely to have higher radionuclide
concentrations) while verifying the relationship and provide a measured soil sample average for
the area.
Multiple sampling locations within a 10 meter by 10 meter block provides a more precise
measurement of the average sum rule for the block than would a single sample location.
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TECHNICAL MEMORANDUM
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The advantage of a composite sample is that the sample will more closely represent the average
over the block yet only one sample requires measurement. The advantage of measurement of
each sampling location (e.g. the four in Figure A.2 of Attachment A) is that the laboratory
uncertainty is averaged out amongst the samples. For example, if the true concentrations were
the same at each sampling point, the average of four locations will average out the laboratory
uncertainty more than the measurement of a single composite. Based on achieving the desired
MDLs for each radionuclide, a composite sample from each 10 meter by 10 meter area is
considered acceptable.
Four locations per 10 meter by 10 meter block has been selected as appropriate for the site as
contamination is generally expected to have smooth spatial variability (is not "spotty")
particularly following remediation. Further, the soil sampling is largely confirmatory ofthe
more extensive gamma radiation measurements and correlation.
Although not required by MARSSIMfor the survey unit, further remediation on a sampled block
will be conducted if the unity rule determined with the soil sample exceeds "1 "for the soil layer.
The remediation will follow the general approach used but would involve a more extensive
gamma radiation survey to define the area and to ensure that the remediation is complete. A
verification soil sample will be collected to confirm that the sampled block meets the sum rule.
The revised, if necessary, correlation relationship will he implemented to determine if there are
any 10 meter by 10 meter blocks with a sum rule prediction that exceeds "1". Any blocks
exceeding the sum rule will be remediated, for example by removing an additional lift and
resurveying."
20.3 Division's Assessment of EFR Responses to Rd 1 Interrogatory White Mesa
RecPlan Rev. 5.0 R313-24; 10CFR40 Appendix A Criterion 6(6); INT 20/1; Scoping.
Characterization, and Final Surveys
EFR reasonably addresses the nine topics contained in Items 1 through 9 of the
interrogatory. The response provides procedures for how gamma surveys may be
conducted and indicate instruments that may be used. These procedures and instruments
are not included in the RPM. Additionally, a discrepancy exists between the RPM and the
response document regarding the frequency of instrument calibrations. Section 3.1.4.2 of
the RPM state "All beta-gamma survey instruments are sent out annually for calibration"
whereas the response states "As indicated in the Mill's RadiationJProtection Reclamation
Manual each existing instrument (Ludlum 19) used will be calibrated by an offsite -third
party every 6 months.
The Division requests that EFR incorporate the substance of these responses into the
further revised Technical Specifications or other documentation pertinent to the
Reclamation Plan. EFR must also resolve the discrepancy stated above. Because this
revised information was not submitted with the response, this interrogatory will remain
open.
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