HRS DOCUMENTATION RECORD COVER SHEET
Name of Site: Lukachukai Mountains Mining District
USEPA ID No.: NNN000920223
Contact Person
Documentation Record:
Kenyon Larsen
Remedial Project Manager
U.S. Environmental Protection Agency, Region 9
75 Hawthorne St, Mail Code: SFD-6-4
San Francisco, CA 94105
(415) 972-3105
Ingrid Chen, PE
Project Manager
Tetra Tech, Inc.
1999 Harrison St., Suite 500
Oakland, CA 94608
(510) 302-6234
The Lukachukai Mountains Mining District (LMMD) site is situated around the community of Cove,
Apache County, Arizona, and is entirely on the Navajo Nation.
Pathways. Components, or Threats Not Scored
Ground Water Migration Pathway
No municipal wells within a 4-mile radius of the site serve as potable supplies; however, shallow wells do
serve the Cove community. The hydrogeology in aquifers providing water for drinking and livestock
watering are complex and not fully characterized; further groundwater characterization is a goal for listing
on the National Priorities List (NPL). In addition, the population served by the wells is low in the Cove
community. Groundwater quality is a significant concern for nearby residents since groundwater is the
only dependable local water source other than imported water. This pathway is unlikely to greatly impact
the site score. The ground water migration pathway will not be scored as part of this Hazard Ranking
System (HRS) package.
Surface Water Migration Pathway
Although several contaminants directly attributable to past uranium mining activities are present at
elevated concentrations in sediments in the Cove Wash Watershed, surface water is not used for drinking
water and no fisheries are on the site. While some isolated riparian wetlands are found along several
branches of the Cove Wash, other surface water sensitive environments are limited on the site. Mine
releases, including from waste piles, pose a threat to sensitive terrestrial environments, including the
habitat for the Mexican spotted owl, which are scored under the soil exposure and subsurface intrusion
pathway. Therefore, as the threat posed by the soil exposure component is sufficient alone to qualify the
site for the NPL, the surface water migration pathway is not scored.
Air Migration Pathway
No data are available to satisfy the HRS requirements for establishing an observed release to the air
migration pathway. Contamination via air migration is a concern to the Cove community, but the data
necessary to document an observed release to air are absent. As such, the air migration pathway will not
be scored as part of this HRS package.
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HRS DOCUMENTATION RECORD
Name of Site: Lukachukai Mountains Mining District (LMMD) Date Prepared: March 2023
USEPA Region: 9
Street Address of Site*: Unincorporated areas of Cove, Round Rock, and Lukachukai Chapters of the
Navajo Nation
City, County, State: Cove, Apache County, Arizona 86544
General Location in the State: The LMMD site is located in the Cove, Round Rock, and Lukachukai Chapters of
the Navajo Nation in Apache County in northeast Arizona. The Lukachukai
Mountains comprise the northern portion of the Chuska Mountain Range.
(Figure 1).
Latitude*: 36° 33' 30.0" north or 36.558335 north
Longitude*: 109° 13' 03.8" west or -109.217720 west
Latitude and longitude coordinates were measured at the approximate former location of the Cove Transfer
Station, which is now the location of an elevated water tank for the Cove community (Ref. 44, pp. 18,26).
* The street address, coordinates, and contaminant locations presented in this HRS documentation record identify
the general area where the site is located. They represent one or more locations the United States Environmental
Protection Agency (USEPA) considers to be part of the site based on the screening information USEPA used to
evaluate the site for NPL listing. USEPA lists national priorities among the known "releases or threatened
releases" of hazardous substances; thus, the focus is on the release and not precisely delineated boundaries. A site
is defined as where a hazardous substance has been "deposited, stored, disposed, or placed, or has otherwise come
to be located." Generally, HRS scoring and the subsequent listing of a release merely represent the initial
determination that a certain area may need to be addressed under the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA). Accordingly, USEPA assumes that the preliminary description of
facility boundaries at the time of scoring will be refined as more information is developed as to where the
contamination has come to be located.
Pathway
Air Migration Pathway NS
Ground Water1 Migration Pathway NS
Soil Exposure and Subsurface Intrusion Pathway 100.00
Surface Water Migration Pathway NS
HRS Site Score 50.00
NS - Not Scored
1 "Ground water" and "groundwater" are synonymous; the spelling is different because "ground water" was codified as part
of the HRS while "groundwater" is the modern spelling.
HRS Documentation Record 1 Lukachukai Mountains Mining District
NNN000920223
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WORKSHEET FOR COMPUTING HRS SITE SCORE
S Pathway
S2 Pathway
Ground Water Migration Pathway Score (Sg„)
NS
NS
Surface Water Migration Pathway Score (Ss„)
NS
NS
Soil Exposure and Subsurface Intrusion Pathway Score (Ssessi)
100.00
10,000
Air Migration Pathway Score (Sa)
NS
NS
c 2 _i_ c 2 _i_ c .2 _i_ C 2
Ogw 1 ^sw 1 Ssessi 1
10,000
(Sgw2 + Ssw2 + Ssessi2 + Sa2) / 4
2,500
HRS Site Score V(Sg„2 + Ssw2 + Ssessi2 + Sa2) / 4
50.00
Notes:
HRS Hazard Ranking System
NS Not scored
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TABLE 5-1
SOIL EXPOSURE COMPONENT SCORESHEET
Factor Categories and Factors
Maximum Value
Value Assigned
Resident Population Threat
Likelihood of Exposure:
1. Likelihood of Exposure:
550
550
Waste Characteristics:
2. Toxicity
a
10,000
3. Hazardous Waste Quantity
a
10,000
4. Waste Characteristics
100
100
Targets:
5. Resident Individual
50
50
6. Resident Population:
6a. Level I Concentrations
b
440
6b. Level II Concentrations
b
0
6c. Resident Population (lines 6a + 6b)
b
440
7. Workers
15
5
8. Resources
5
0
9. Terrestrial Sensitive Environments
C
90
10. Targets (lines 5 +6c+ 7 + 8 +9)
b
585
Resident Population Threat Score:
11. Resident Population Threat (lines 1x4x10)
b
32,175,000
Nearby Population Threat
Likelihood of Exposure
12. Attractiveness/Accessibility
100
Not Scored
13. Area of Contamination
100
Not Scored
14. Likelihood of Exposure
500
Not Scored
Waste Characteristics:
15. Toxicity
a
Not Scored
16. Hazardous Waste Quantity
a
Not Scored
17. Waste Characteristics
100
Not Scored
Targets:
18. Nearby Individual
l
Not Scored
19. Population Within 1 Mile
b
Not Scored
20. Targets (lines 18 + 19)
b
Not Scored
Nearby Population Threat Score:
21. Nearby Population Threat (lines 14 x 17 x 20)
b
0
SOIL EXPOSURE COMPONENT SCORE
22. Soil Exposure Component Scored (Sse) (lines [11+21]/
82,500, subject to maximum of 100)
100
100
Notes:
a Maximum value applies to waste characteristics category.
b Maximum value not applicable.
c No specific maximum value applies to factor. However, the pathway score based solely on terrestrial sensitive environments is limited
to a maximum of 60.
d Do not round to nearest integer.
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REFERENCES
Ref.
No. Description of the Reference
1. U.S. Environmental Protection Agency (EPA). Hazard Ranking System, Title 40 Code of Federal
Regulations (CFR) Part 300, Appendix A (55 Federal Register [FR] 51583, Dec. 14, 1990, as amended at
82 FR 2779, Jan. 9, 2017; 83 FR 38037, Aug. 3, 2018), as published in the Code of Federal Regulations
on July 1, 2019, with two attachments. Attachment A: Federal Register Vol. 55, No. 241. December 14,
1990. Hazard Ranking System Preamble. Attachment B: Federal Register Vol. 82, No. 5, January 9, 2017.
Addition of a Subsurface Intrusion Component to the Hazard Ranking System Preamble. 197 Pages.
2. USEPA. 2022. Superfund Chemical Data Matrix (SCDM). Online query of SCDM. Query accessed on 8-
21-2022. https://www.epa.gov/superfund/superfund-chemical-data-matrix-scdm-querv. 21 pages.
3. Tetra Tech, Inc. (Tetra Tech). 2019. Northern Agency Tronox Mines. "Final - Appendix H3: Site-Specific
Removal Site Evaluation Report: Mesa I Mine 10 (M3)." Response, Assessment, and Evaluation
Services. Contract No. EP-S9-17-03. Task Order 0001. October 10. 199 pages.
4. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H4: Site-Specific Removal Site
Evaluation Report: Mesa I Mine 11 (M4)." Response, Assessment, and Evaluation Services. Contract
No. EP-S9-17-03. Task Order 0001. October 10. 234 pages.
5. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H5: Site-Specific Removal Site
Evaluation Report: Mesa I Mine 12 (M5)." Response, Assessment, and Evaluation Services. Contract
No. EP-S9-17-03. Task Order 0001. October 10. 252 pages.
6. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H6: Site-Specific Removal Site
Evaluation Report: Mesa I Mine 13 (M6)." Response, Assessment, and Evaluation Services. Contract
No. EP-S9-17-03. Task Order 0001. October 10. 275 pages.
7. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H7: Site-Specific Removal Site
Evaluation Report: Mesa I Mine 14 (M7)." Response, Assessment, and Evaluation Services. Contract
No. EP-S9-17-03. Task Order 0001. October 10. 239 pages.
8. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H8: Site-Specific Removal Site
Evaluation Report: Mesa I Mine 15 (M8)." Response, Assessment, and Evaluation Services. Contract No.
EP-S9-17-03. Task Order 0001. October 10. 247 pages.
9. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H9: Site-Specific Removal Site
Evaluation Report: Mesa I 1/4 Mine (M9)." Response, Assessment, and Evaluation Services. Contract
No. EP-S9-17-03. Task Order 0001. October 10. 186 pages.
10. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H10: Site-Specific Removal Site
Evaluation Report: Mesa I 1/2 Mine (M10)." Response, Assessment, and Evaluation Services. Contract
No. EP-S9-17-03. Task Order 0001. October 10. 184 pages.
11. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix HI 1: Site-Specific Removal Site
Evaluation Report: Henry Phillips Mine (Ml 1)." Response, Assessment, and Evaluation Services.
Contract No. EP-S9-17-03. Task Order 0001. October 10. 187 pages.
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12. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H12: Site-Specific Removal Site
Evaluation Report: Mesa I 1/2 West Mine (M12)." Response, Assessment, and Evaluation Services.
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13. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H13: Site-Specific Removal Site
Evaluation Report: Mesa VI Mine (M13)." Response, Assessment, and Evaluation Services. Contract No.
EP-S9-17-03. Task Order 0001. October 10. 223 pages.
14. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H14: Site-Specific Removal Site
Evaluation Report: Frank Jr. Mine (M14)." Response, Assessment, and Evaluation Services. Contract No.
EP-S9-17-03. Task Order 0001. October 10. 205 pages.
15. Tetra Tech. Northern Agency Tronox Mines. "Final - Appendix H15: Site-Specific Removal Site
Evaluation Report: Mesa V Incline (M15)." Response, Assessment, and Evaluation Services. Contract
No. EP-S9-17-03. Task Order 0001. October 10. 220 pages.
16. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H16: Site-Specific Removal Site
Evaluation Report: Mesa V Adit (M16)." Response, Assessment, and Evaluation Services. Contract No.
EP-S9-17-03. Task Order 0001. October 10. 233 pages.
17. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H17: Site-Specific Removal Site
Evaluation Report: Mesa V Mine - 103 (M17)." Response, Assessment, and Evaluation Services.
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18. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H18: Site-Specific Removal Site
Evaluation Report: Mesa V Mine - 508 (M18)." Response, Assessment, and Evaluation Services.
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19. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H19: Site-Specific Removal Site
Evaluation Report: Mesa IV 1/2 Mine and Simpson 181 (M19)." Response, Assessment, and Evaluation
Services. Contract No. EP-S9-17-03. Task Order 0001. October 10. 203 pages.
20. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H20: Site-Specific Removal Site
Evaluation Report: Mesa IV, Mine No. 1 (M20)." Response, Assessment, and Evaluation Services.
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21. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H21: Site-Specific Removal Site
Evaluation Report: Mesa IV, Mine No. 2 (M21)." Response, Assessment, and Evaluation Services.
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22. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H22: Site-Specific Removal Site
Evaluation Report: Mesa IV, Mine No. 3 (M22)." Response, Assessment, and Evaluation Services.
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23. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H23: Site-Specific Removal Site
Evaluation Report: Mesa IV, West Mine (M23)." Response, Assessment, and Evaluation Services.
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24. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H24: Site-Specific Removal Site
Evaluation Report: Mesa II Pit (M24)." Response, Assessment, and Evaluation Services. Contract No.
EP-S9-17-03. Task Order 0001. October 10. 225 pages.
25. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H25: Site-Specific Removal Site
Evaluation Report: Mesa I 3/4 Incline (M25)." Response, Assessment, and Evaluation Services. Contract
No. EP-S9-17-03. Task Order 0001. July 26. 196 pages.
26. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H26: Site-Specific Removal Site
Evaluation Report: Mesa I 3/4, Mine No. 2, P-150 (M26)." Response, Assessment, and Evaluation
Services. Contract No. EP-S9-17-03. Task Order 0001. October 10. 185 pages.
27. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H27: Site-Specific Removal Site
Evaluation Report: Mesa II, Mine No. 1 & 2, P-21 (M27)." Response, Assessment, and Evaluation
Services. Contract No. EP-S9-17-03. Task Order 0001. October 10. 231 pages.
28. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H28: Site-Specific Removal Site
Evaluation Report: Mesa II, Mine No. 1, P-150 (M28)." Response, Assessment, and Evaluation Services.
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29. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H29: Site-Specific Removal Site
Evaluation Report: Mesa II, Mine 4 (M29)." Response, Assessment, and Evaluation Services. Contract
No. EP-S9-17-023. Task Order 0001. October 10. 191 pages.
30. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H30: Site-Specific Removal Site
Evaluation Report: Mesa II 1/2 Mine (M30)." Response, Assessment, and Evaluation Services. Contract
No. EP-S9-17-03. Task Order 0001. October 10. 233 pages.
31. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H31: Site-Specific Removal Site
Evaluation Report: Mesa II 1/2, Mine 4 (M31)." Response, Assessment, and Evaluation Services.
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32. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H32: Site-Specific Removal Site
Evaluation Report: Mesa III Mine (M32)." Response, Assessment, and Evaluation Services. Contract No.
EP-S9-17-03. Task Order 0001. October 10. 220 pages.
33. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H33: Site-Specific Removal Site
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34. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H34: Site-Specific Removal Site
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36. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H36: Site-Specific Removal Site
Evaluation Report: Black No. 2 Mine (West) (M36)." Response, Assessment, and Evaluation Services.
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37. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H37: Site-Specific Removal Site
Evaluation Report: Flag No. 1 Mine (M37)." Response, Assessment, and Evaluation Services. Contract
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38. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H38: Site-Specific Removal Site
Evaluation Report: Step Mesa Mine (M38)." = Response, Assessment, and Evaluation Services. Contract
No. EP-S9-17-03. Task Order 0001. October 10. 184 pages.
39. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix H39: Site-Specific Removal Site
Evaluation Report: Tommy James Mine (M39)." Response, Assessment, and Evaluation Services.
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40. Tetra Tech. 2019. Northern Agency Tronox Mines "Final - Appendix H40: Site-Specific Removal Site
Evaluation Report: Cove Transfer Station (M40)." Response, Assessment, and Evaluation Services.
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41. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final -^Appendix H41: Site-Specific Removal Site
Evaluation Report: Mesa I Camp (T17)." Response, Assessment, and Evaluation Services. Contract No.
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42. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final -^Appendix H42: Site-Specific Removal Site
Evaluation Report: NA-0344B (T23)." Response, Assessment, and Evaluation Services. Contract No.
EP-S9-17-03. Task Order 0001. October 10. 205 pages.
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Report." Response, Assessment, and Evaluation Services. Contract No. EP-S9-17-03. Task Order 0001.
October 10. 7,164 pages.
44. Ecology & Environment, Inc. (E&E). 2013. "Cove Transfer Station Sites 1 and 2, Abandoned Uranium
Mine Waste Removal Action Report. Navajo Nation, Cove Chapter, Apache Country, Arizona." Prepared
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Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 11 pages.
48. EPA. 2022. "Using Qualified Data to Document an Observed Release and Observed Contamination."
Quick Reference Fact Sheet. USEPA Directive 9285.7-89FS. November. 20 pages.
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49. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - NA-0343 AUM
Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 11 pages.
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Side AUM Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 11 pages.
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Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 11 pages.
55. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - Cato No. 1 Pit
AUM Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 12 pages.
56. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - Cove Mesa
Mines (Cato Sells) AUM Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 24
pages.
57. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - West Mesa
Mine AUM Site." Prepared for EPA under Contract No. W91238-06-F-0083. March. 12 pages.
58. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - East Mesa
Mines AUM Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 11 pages.
59. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - Cove Mesa
Mines (AEC Plot 7) AUM Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March.
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60. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - NA-0332 AUM
Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 10 pages.
61. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - NA-0333 AUM
Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 10 pages.
62. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Removal Site Evaluation Report." Response,
Assessment, and Evaluation Services. Contract No. EP-S9-17-03. Task Order 0001. October 10. 342
pages.
63. Jacobs, Inc. (Jacobs). 2022. "Cove Mine Sites Removal Site Evaluation Report." Final. Prepared for the
Cyprus Amax Minerals Company. Contract No. FES0305201427NWO. October. 92 pages.
64. Weston. 2014. "Site Reassessment Mesa I, Mines 10-15 Abandoned Uranium Mine." Prepared for
USEPA under Contract No. W91238-11-D-001. January. 72 pages.
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65. Neptune and Company, Inc. and TerraSpectra Geomatics. 2018. "Cove Chapter Abandoned Uranium
Mines, Final Preliminary Conceptual Site Model." July. 251 pages.
66. EPA Project Note Regarding Lukachukai Mountains - Particular Area, Relatively Small in Size,
Important to Maintenance of a Unique Biotic Community. 2022. From EPA Kenyon Larsen, Remedial
Project Manager, and Cove Chapter President James Benally. July 20. 1 page.
67. EPA Project Note Regarding Lukachukai Mountains - Terrestrial Breeding Area for Large or Dense
Aggregation of Vertebrates. 2022. From EPA Kenyon Larsen, Remedial Project Manager, and Cove
Chapter President James Benally. July 20. 1 page.
68. Navajo Nation Division of Natural Resources Department of Fish and Wildlife. 2020. "Navajo
Endangered Species List." Resources Committee Resolution No. RDCJA-01-20. February 13. 4 pages.
69. United States Fish and Wildlife Service (USFWS). 2022. "List of Species Believed to or Known to Occur
in Arizona." Environmental Conservation Online System. Accessed August 21.
https://ecos.fws.gov/ecp/report/species-listings-bv-
state?stateAbbrev=AZ&stateName=Arizona&statusCategorv=Listed. 10 pages.
70. EPA Project Note Regarding the Number of Students and Workers at the Cove Day School. 2022. From
EPA Jesse Kass and Kenyon Larsen, Remedial Project Managers, and Cove Day School Head
Teacher/Administrator Willeen J. Benally. September 2. 1 page.
71. TerraSpectra Geomatics. 2007. "Abandoned Uranium Mines and the Navajo Nation, Navajo Nation AUM
Screening Assessment Report and Atlas with Geospatial Data." August. 198 pages.
72. Tetra Tech. 2020.Northern Agency Tronox Mines. Engineering Evaluation/Cost Analysis "Mexican
Spotted Owl Survey Report 2019 Nesting Season." Response, Assessment, and Evaluation Services.
Contract No. EP-S9-17-03. Task Order 0016. October 16. 125 pages.
73. Tetra Tech. 2022. "Preliminary Assessment Report. Lukachukai Mountains Mining District." Contract
No. EP-S9-17-03. October 30. 2,157 pages.
74. New Order Environmental Services, LLC. Bureau of Indian Affairs (BIA), Division of Facilities
Management and Construction (DFMC). 2019. "Radiological Testing Gamma Walkover Services, Cove
Day School, Red Valley, Arizona." October 25. 22 pages.
75. Jacobs. 2022. "Appendix A-l: Cato No. 2 Mine Site." In "Cove Mine Sites Removal Sites Evaluation
Report." Prepared for the Cyprus Amax Minerals Company. Contract No. FES0305201427NWO.
October. 45 pages.
76. Jacobs. 2022. "Appendix A-2: Frank No. 1 Mine Site." In "Cove Mine Sites Removal Sites Evaluation
Report." Prepared for the Cyprus Amax Minerals Company. Contract No. FES0305201427NWO.
October. 95 pages.
77. Jacobs. 2022. "Appendix A-3: Frank No. 2 Mine Site." In "Cove Mine Sites Removal Sites Evaluation
Report." Prepared for the Cyprus Amax Minerals Company. Contract No. FES0305201427NWO.
October. 41 pages.
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78. Jacobs. 2022. "Appendix A-4: NA-0316 Mine Site." In "Cove Mine Sites Removal Sites Evaluation
Report." Prepared for the Cyprus Amax Minerals Company. Contract No. FES0305201427NWO.
October. 40 pages.
79. Jacobs. 2022. "Appendix A-5: Mesa IV 1/4 Mine Site." In "Cove Mine Sites Removal Sites Evaluation
Report." Prepared for the Cyprus Amax Minerals Company. Contract No. FES0305201427NWO.
October. 44 pages.
80. Jacobs. 2022. "Appendix A-6: Mesa III Northwest Mine Site." In "Cove Mine Sites Removal Sites
Evaluation Report." Prepared for the Cyprus Amax Minerals Company. Contract No.
FES0305201427NWO. October. 39 pages.
81. Jacobs. 2022. "Appendix A-7: Mesa III West Mine Site." In "Cove Mine Sites Removal Sites Evaluation
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October. 43 pages.
82. Jacobs. 2022. "Appendix A-8: Mesa II 1/4 Mine Site." In "Cove Mine Sites Removal Sites Evaluation
Report." Prepared for the Cyprus Amax Minerals Company. Contract No. FES0305201427NWO.
October. 41 pages.
83. Jacobs. 2022. "Appendix A-9: Billy Topaha Mine Site." In "Cove Mine Sites Removal Sites Evaluation
Report." Prepared for the Cyprus Amax Minerals Company. Contract No. FES0305201427NWO.
October. 44 pages.
84. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1809426 and 1809427." April 9. 187 pages.
85. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1806221 and 1806236." January 24. 167
pages.
86. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1807369, 1807370, and 1809587." February
27. 116 pages.
87. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1809428 and 1809429." April 5. 188 pages.
88. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1807350 and 1807351." February 11. 166
pages.
89. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1805321 and 1805322." October 18. 173
pages.
90. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1805319 and 1805320." October 16. 172
pages.
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91. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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92. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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93. Tetra Tech. 2022. "Lukachukai Mountain Mining District Hazard Ranking System Site Investigation
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94. Reference No. Reserved
95. Reference No. Reserved
96. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1808356 and 1808360." February 19. Ill
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97. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1810076 and 1810077." April 15. 230 pages.
98. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1810026 and 1810027." April 17. 281 pages.
99. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1808483 and 1808484." February 19. 121
pages.
100. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1807264 and 1807265." January 30. 185 pages.
101. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1810079 and 1810080." April 17. 313 pages.
102. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1807353 and 1807354." February 12. 175
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103. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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104. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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106. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1806626 and 1806627." January 11. 168 pages.
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107. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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pages.
108. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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109. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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110. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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111. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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112. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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113. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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114. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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115. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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116. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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117. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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118. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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119. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1809283 and 1809284." March 26. 151 pages.
120. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1809473 and 1809474." March 11. 186 pages.
121. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1809424 and 1809425." April 9. 103 pages.
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122. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1806224 and 1806234." January 24. 105 pages.
123. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1809475 and 1809476." April 2. 210 pages.
124. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1806311 and 1806312." December 18. 53
pages.
125. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1806161 and 1806162." December 18. 173
pages.
126. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1807262 and 1807263." January 30. 175 pages.
127. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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116 pages.
128. Reference No. Reserved
129. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1810024 and 1810025." April 17. 283 pages.
130. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1810072 and 1810073." April 17. 196 pages.
131. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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pages.
132. Reference No. Reserved
133. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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134. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1808302 and 1808303." February 19. Ill
pages.
135. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1807325 and 1807326." February 11. 176
pages.
136. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1809418 and 1809419." April 12. 150 pages.
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137. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1807330 and 1807331." January 4. 209 pages.
138. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1807357 and 1807358." February 13. 162
pages.
139. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1805035 and 1805036." October 12. 109
pages.
140. Jacobs. 2020. "Appendix E-l: Site-Specific Laboratory Reports Cato No. 2." In "Cove Mine Sites
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141. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1805581 and 1805582." November 1. 99
pages.
142. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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143. Reference No. Reserved
144. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1810001 and 1810002." April 12. 144 pages.
145. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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pages.
146. Reference No. Reserved
147. Reference No. Reserved
148. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1805038 and 1805039." October 12. 112
pages.
149. Jacobs. 2020. "Appendix E-2: Site-Specific Laboratory Reports Frank No. 1." In "Cove Mine Sites
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150. Tetra Tech. 2018. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1805042 and 1805043." October 15. 74 pages.
151. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1809412 and 1809413." April 12. 151 pages.
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152. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1808494 and 1808495." March 11. 21 pages.
153. Reference No. Reserved
154. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1809479and 1809480." April 1. 302 pages.
155. Reference No. Reserved
156. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
0001. Contract No. EP-S9-17-03. Laboratory Report Nos. 1809453 and 1809454." April 5. 160 pages.
157. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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158. Tetra Tech. 2019. "Data Validation Report. Response, Assessment, and Evaluation Services. Task Order
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160. Reference No. Reserved
161. Reference No. Reserved
162. Jacobs. 2020. "Appendix E-3: Site-Specific Laboratory Reports Frank No. 2." In "Cove Mine Sites
Removal Sites Evaluation Report." Prepared for the Cyprus Amax Minerals Company. Contract No.
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163. Jacobs. 2020. "Appendix E-4: Site-Specific Laboratory Reports NA-0316." In "Cove Mine Sites Removal
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164. Jacobs. 2020. "Appendix E-5: Site-Specific Laboratory Reports Mesa IV 1/4." In "Cove Mine Sites
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165. Jacobs. 2020. "Appendix E-6: Site-Specific Laboratory Reports Mesa III Northwest." In "Cove Mine
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166. Jacobs. 2020. "Appendix E-7: Site-Specific Laboratory Reports Mesa III West." In "Cove Mine Sites
Removal Sites Evaluation Report." Prepared for the Cyprus Amax Minerals Company. Contract No.
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167. Jacobs. 2020. "Appendix E-8: Site-Specific Laboratory Reports Mesa II 1/4." In "Cove Mine Sites
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168. Jacobs. 2020. "Appendix E-9: Site-Specific Laboratory Reports Billy Topaha." In "Cove Mine Sites
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169. Jacobs. 2020. "Appendix E: Background Laboratory Reports." In "Cove Mine Sites Removal Sites
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170. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - Jimmie King
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171. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - Joleo Mine
AUM Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 13 pages.
172. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - Cisco Mine
AUM Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 12 pages.
173. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - Camp Mine
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174. Validata Chemical Services, Inc. 2022. Data Validation Summary Report - Radiochemistry. Response,
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175. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - Cove Mesa
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176. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - Mexican Cry
Mines." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 14 pages.
177. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - Hall Mine
AUM Site." Prepared for USEPA under Contract No. W91238-06-F-0083. March. 15 pages.
178. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - Nakai Chee
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179. Weston. 2010. "Navajo Abandoned Uranium Mine Northern Region Site Screen Report - Tom Joe No. 6
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180. Reference No. Reserved
181. Reference No. Reserved
182. Reference No. Reserved
183. Tetra Tech. 2020. Northern Agency Tronox Mines. "Tommy James Mine Site-Specific Removal Site
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184. ALS Environmental Laboratories. 2022. "Gamma Spectroscopy Case Narrative - LMMD HRS Site
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190. Reference No. Reserved
191. Navajo Nation Division of Natural Resources Reclamation Department. 1991. "Environmental
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192. Clifford, A. 2015. Carrizo Mountain Environmental & Herbarium, Inc. "Biologic Baseline Data, Geology
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193. Kosatka, R. F. 1956. U.S. Atomic Energy Commission. Grand Junction Operations Office Exploration
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1950-1955: Open-File Report RME-199. March 30. 31 pages.
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195. GEL Laboratories LLC. 2022. "NPL LMMD HRS Investigation Analytical Results Report, Work Order:
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196. GEL Laboratories LLC. 2022. "NPL LMMD HRS Investigation Analytical Results Report, Work Order:
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199. U.S. District Court. 2017. Consent Decree. United States of America and Navajo Nation v. Cyprus Amax
Minerals Company and Western Nuclear, Inc. District of Arizona. 161 pages.
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200. Tetra Tech. 2022. Project Note Regarding Radium-226 Background Statistics. December 6. 3 pages.
201. GEL Laboratories LLC. 2022. "NPL LMMD HRS Investigation Analytical Results Report, Work Order:
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202. GEL Laboratories LLC. 2022. "NPL LMMD HRS Investigation Analytical Results Report, Work Order:
596524." Response, Assessment, and Evaluation Services. November 8. 786 pages
203. GEL Laboratories LLC. 2022. "NPL LMMD HRS Investigation Analytical Results Report, Work Order:
596528." Response, Assessment, and Evaluation Services. November 8. 711 pages
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205. Weston. 2018. Final Assessment Report Cove Wash Watershed Assessment Site, Navajo Nation, Cove
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206. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix K: Access Road Report. Response,
Assessment, and Evaluation Services. Contract No. EP-S9-17-03. Task Order 0001. October 10. 140
pages.
207. Tetra Tech. 2019. Northern Agency Tronox Mines. "Final - Appendix J: Drainage Investigation Report."
Response, Assessment, and Evaluation Services. Contract No. EP-S9-17-03. Task Order 0001. October
10. 451 pages.
208. Dare, W.L. United States Department of the Interior, Bureau of Mines. 1959. "Underground Mining
Methods and Costs at Three Salt Wash Uranium Mines of the Climax Uranium Co.". TN23.U71 No.
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209. Gallagher & Kennedy Attorneys at Law. 2008. "Request for Information - Navajo Nation Abandoned
Uranium Mine Sites." August 29. 19 pages.
210. Tetra Tech. 2022. Project Note Regarding Lukachukai Mountain Mining District - Mining History.
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211. EPA. 1995. "Establishing Areas of Observed Contamination." Quick Reference Fact Sheet. Office of
Solid Waste and Emergency Response Directive 9285.7-18FS. September. 7 pages.
212. Tetra Tech Project Note with Attachments. 2022. Subject: Step Mesa Radium-226 and Metals Results
from 2022 Sampling. Attachments: GEL Laboratories LLC Analytical Results Report, Step Mesa Photo
Log, and Field Notes. December 2. 3,147 pages.
213. Tetra Tech. Project Note with Attachments. 2022. Subject: Mexican Cry Radium-226 and Metals Results
from 2022 Sampling. Attachments: GEL Laboratories LLC Analytical Results Report, Mexican Cry
Photo Log, and Field Notes. December 2. 4,867 pages.
214. Tetra Tech. Project Note with Attachments. 2022. Subject: Cove Mesa Radium-226 and Metals Results
from 2022 Sampling. Attachments: GEL Laboratories LLC Analytical Results Report, Cove Mesa Photo
Log, and Field Notes. December 6. 4,889 pages.
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215. U.S. Department of the Interior Office of Surface Mining Reclamation and Enforcement. 2001.
"Abandoned Mine Land Problem Area Description NA-0332.". March. 18 pages.
216. U.S. Department of the Interior Office of Surface Mining Reclamation and Enforcement. 2001.
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218. Jacobs. 2022. "Appendix F: Statistical Documentation." In "Cove Mine Sites Removal Sites Evaluation
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219. Weston. 2017. Draft Final Wetland Delineation Report. Cove Wash Watershed Assessment Site. Prepared
for EPA under Contract No. EP-S5-13-02. December. 127 pages.
220. Tetra Tech. 2023. Project Note with Attachments. Subject: Removal Site Evaluation Report Chains of
Custody. Attachments: Chains of Custody for Soil Samples Collected During the 2018 Northern Agency
Tronox Mines Removal Site Evaluation. January 12. 919 pages.
221. Tetra Tech. 2018. "Northern Agency Tronox Mines Removal Site Evaluation Work Plan." Response,
Assessment, and Evaluation Services. Contract No. EP-S9-17-02. Task Order 0001. May 14. 3,816 pages.
222. CH2M HILL Engineers, Inc. 2017. "Removal Site Evaluation Work Plan for Consent Decree Sites".
Prepared for the Cyprus Amax Minerals Company. October. 908 pages.
223. Navajo AML Reclamation Department. Cove 2 AMLR Project. Technical Specifications. Date unknown,
but embedded maps are from April 1999. 53 pages.
224. U.S. Fish and Wildlife Service, Department of the Interior. 2004. Endangered and Threatened Wildlife
and Plants; Final Designation of Critical Habitat of the Mexican Spotted Owl; Final Rule. Title 50 CFR
Part 17, as published in the Federal Register August 31. 118 pages.
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Located 2 Miles Northeast
Ifton Indian Route 33
Cove Transfer Station South
f
¦
~ Lukachukai Mountain Mining District
Mines / Other Sources1
Cove Transfer Station
I I
Flag Mesa
I I
Knife Edge Mesa
I i
Mesa I
~
Mesa II
¦
Mesa III
~
Mesa IV
~
Mesa V and VI
: i
Mexican Cry Mesa
HI
Step Mesa
~ Navajo Nation Boundary
I l Navajo Nation Chapter Boundary
Hopi Reservation
Historic Haul Route
Wash
Well (Domestic Use)
Cove Day School
Note:
'Reference 71.
1 inch - 3,400 feet
1:40,800
3,400 1,700 0
3,400
i Feet
LUKACHUKAI MOUNTAINS
MINING DISTRICT ¦
COVE, LUKACHUKAI, AND
ROUND ROCK CHAPTERS
Prepared For: U.S. EPA Region 9
^,tDSrx
(#)
At -.11
Task Order No.:
0016
Location:
NAVAJO NATION
Prepared By:
TETRA TECH
Contract No.:
EP-S9-17-03
1/1 2/2023
HRS Documentation Record
20
Coordinate System:
NAD 1983 State Plane Arizona East
FIRS 0201 Feet Transverse Mercator
Lukachukai Mountains Mining District
NNN000920223
-------
Chapter
Cove Day School
Frank Jr. Mine
Mesa VI Mine ¦
Mexican Cry Mine -197
Mexican Cry Mine -198
' NA-0344B
Mesa V Incline
Mesa V
Mesa
Mesa V Mine - 508
Mesa IV 1/2 Mine and Simpson 181
Cov087,
Nakai Chee Begay Mine
North Portal, Frank No. 1 Mine
Cov068
East Portal, Frank No. 1 Mine —
Mesa I Mine 15
Frank No. 2
Mesa II Pit
Mesa I Mine 12
NA-0316
Mesa IV 1/4 Mine
Mesa I Mine 10
CovOOO
Mesa II, Mine 4
Mesa I Mine 14
Jimmie King No. 9 Mine
Henry Phillips Mine
Mesa III Mine
Mesa I11/2, Mine 4
Mesa II,VI
Mine NoT1,'P-150
Mesa 11/2, West Mine
Mesa I11/2 Mine '
Mesa I11/4 Mine
Mesa II,
Mine NoTi&2Tp-21
Tommy James Mine
^ Mesa I 3/4,
Mine n672,"P150
Mesa I 3/4 Incline
Step Mesa Mine
Colorado
Billy Topaha
c,ov;e
Chapter
Black No. 1 Mine
Cisco Mine ,
Black No. 2 Mine (West)
Black No. 2 Mine
New Mexico
9 : : -T—
t
/
Cove
Locati
on
*
i r
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Cove Transfer Station 2 is
Located 2 Mi es Northeast
on Indian Route 33;
KShato.* W*'' '
E *• ¦* r v
J*
Cove Transfer Station
Round Rock
Cove Transfer Station South
wk mm
e*', i " > Vi- J
Ha Mine
^AdSt ~ Mesa IV, Mine No. 2
Tom Joe No. 6
Mesa IV, Mine No. 3
IV, Mine No. 1 , Mesa I Mine 11
South Portal, Frank No. 1 Mine
Mesa IV, West Mine
Mesa I Mine 13
ESS
Mesa I Camp
Mesa III, Northwest Mine
Mesa IV, East Side
Mesa 1/2 Mine
Mesa III, West Mine
— Mesa 11/4
"
Mine
Flag No. 1 Mine
Lukachukai
Chapter
m
I
ine 1 Joleo Mine
•# £ ***
I
NA-0343 1
Knife Edge Mesa Mine
¦ Lukachukai Mountain Mining District
Haul Road Sample Location with
® Elevated Metals or Radionuclides
Mines I Other Sources1
¦1
Cove Transfer Station
I I
Flag Mesa
Knife Edge Mesa
I I
Mesa I
~
Mesa II
Mesa III
~
Mesa IV
~
Mesa V and VI
I I
Mexican Cry Mesa
¦¦
Step Mesa
~ Navajo Nation Boundary
I J Navajo Nation Chapter Boundary
KX>6I Hopi Reservation
Historic Haul Route
Wa sh
Well (Domestic Use)
[5 Cove Day School
Note:
Reference 71.
1 inch - 3,400 feet
1:40,800
3,400 1,700 0
3,400
I Feet
LUKACHUKAI MOUNTAINS
MINING DISTRICT ¦
MINE ROADS
Prepared For: U.S. EPA Region 9
4Bt'\
mi
Task Order No.:
Location:
NAVAJO NATION
Prepared By:
TETRA TECH
Contract No.:
EP-S9-17-03
1/1 2/2023
The source of this map image is Esri,
used by the EPA with Esri's permission.
Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
Figure No.:
2
HRS Documentation Record
Lukachukai Mountains Mining District
NNN000920223
-------
E
...
"ransfer Station 2 is
d 2 Miles Northeast
Indian Route 33; -
¦ Lukachukai Mountain Mining District
Sediment Sample Location with
Elevated Metals or Radionuclides
Mines I Other Sources1
¦1
Cove Transfer Station
I I
Flag Mesa
Knife Edge Mesa
I I
Mesa I
~
Mesa II
m
Mesa III
~
Mesa VI
~
Mesa V and VI
i i
Mexican Cry Mesa
¦¦
Step Mesa
~ Navajo Nation Boundary
I J Navajo Nation Chapter Boundary
KX>6I Hopi Reservation
Historic Haul Route
Wash
Well (Domestic Use)
[5 Cove Day School
Note:
Reference 71.
1 inch = 3,740 feet
1:44,880
3,740 1,870 0
N
3,740
I Feet
LUKACHUKAI MOUNTAINS
MINING DISTRICT ¦
SURFACE WATER
Prepared For: U.S. EPA Region 9
Q %
w
Task Order No.:
0016
Location:
NAVAJO NATION
Prepared By:
TETRA TECH
Contract No.:
EP-S9-17-03
1/1 2/2023
Coordinate System:
NAD 1983 State Plane Arizona East
FIRS 0201 Feet Transverse Mercator
Figure No.:
3
HRS Documentation Record
22
Lukachukai Mountains Mining District
NNN000920223
-------
B9-S S04-01 -050718
B9-SS12-01-050718
M8ISS106-01-0927.18
M4-XS63-02-050718
M4-SS176-01 -091818
M8-SS120-01 -092718
M3-XS36-01 -043018,
M3-SS36-01 -091618
M5-SS149-01-093018
T17-XS144-01-042618
T17-SS143-01-042618
B12-SS13-01-050918
mm*
M7-XS162A\01;081518
M5-SS185-01-093018
M7-SS161 -01 -091618
M10-SS10-01-092818
M10-XS43-01 -082118
B15-SS11 -01 -071118
M9-XS28A-01 -081718
Notes:
Waste pile boundaries are estimated; samples that
appear to be outside the waste pile boundaries are
representative of waste from the waste pile.
AOC Area of concern
The source of this map image is Esri, used by the EPA
with Esri's permission.
Waste Sample Location1
Background Surface Soil Sample Location
0-6 inches
Waste Pile
Background Study Area
Historic Haul Route
Wash
Task Order No.
Contract No.
Location:
References:
3, p.145; 4, pp.146-147; 5, p.149; 6, pp. 145, 148; 7,
pp.148-149; 8, pp.149, 151, 152; 9, p.140; 41, pp.142
145; 10, p.138; 43, pp.947, 1263, 1369, 1574.
3/7/2023
1999 Harrison Street, Suite 500
Oakland, CA94612
Coordinate System:
NAD 1983 State Plane Arizona East FIPS 0201 Feet
HRS Documentation Record
23
Lukacluikai Mountains Mining District
NNN000920223
-------
SS-07-NNWP02-001-10102
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The source of this map images is Esn,
used by the EPA with Esri's
• Waste Sample Location1
l> ;,1 Waste Pile
— Historic Haul Route
Wash
Notes:
Waste pile boundaries are estimated; samples that
appear to be outside the waste pile boundaries are
representative of waste from the waste pile.
AOC Area of concern
References: 12, p.139; 25, p.142; 28, p.138; 27, p.146;
29, p.139; 24, p.143; 82, p.22; 11. p.136; 83, p.22.
Prepared for: U.S. EPA Region 9
^tDSr^,
PRO^
Prepared By:
TETRA TECH
1999 Harrison Street, Suite 500
Oakland, CA94612
MESA II
WASTE SAMPLE LOCATIONS
Task Order No.:
0016
Location:
COVE CHAPTER
NAVAJO NATION
Contract No.:
EP-S9-1 7-03
Date:
3/7/2023
Figure No.:
Coordinate System:
NAD 1983 State Plane Arizona East FIPS 0201 Feet
HRS Documentation Record
24
Lukachukai Mountains Mining District
NNN000920223
-------
SS-C0-B1-021110142017i
• V
Morrison Formation
B24-SS06-Q1 -071618
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1,400
=~ Feet
Prepared for: U.S. EPA Region 9
Background Surface Soil Sample Location
0-6 inches
Background Study Area (BSA)
Iv^fl Waste Pile
Historic Haul Route
Wash
MESA II
BACKGROUND SAMPLE LOCATIONS
Note:
AOC Area of concern
References: 43, pp.1053,1470, 2502, 3022; 63, p.64
The source of this map images is Esri, used by the
EPA with Esri's permission.
Prepared By:
It
TETRA TECH
1999 Harrison Street, Suite 500
Oakland, CA94612
Task Order No.:
Contract No.:
Figure No.:
0016
EP-S9-1 7-03
Location:
Date:
6
COVE CHAPTER
3/6/2023
NAVAJO NATION
Coordinate System:
NAD 1983 State Plane Arizona East FIPS 0201 Feet
HRS Documentation Record
25
Lukachukai Mountains Mining District
NNN000920223
-------
&lA£ni
SS-08-CAWg0ll00,1;06082i
EHfe
mm
BIS
cc nn mm\a/doi nno m-ico m
SS-09-N NWP01 -002-10152,
The source of this map image is Esri,
used by the EPA with Esrrs permission.
• Waste Sample Location1
\'ix\ V\feste Pile
— Historic Haul Route
¦ V\fesh
V '
V
Notes:
1V\feste pile boundaries are estimated;
samples that appear to be outside the
waste pile boundaries are representative of
waste from the waste pile.
AOC Area of concern
References: 30, p.143; 31, p.143; 32, p.146;
80, p.20; 81, p.20.
1 inch = 300 feet
1:3,600
300 150 0
W~
300
^3 Feet
MESA III
WASTE SAMPLE LOCATIONS
I Prepared For: U.S. EPA Region 9
Prepared By:
^tDST^
It
TETRA TECH
1999 Harrison Street, Suite 500
Oakland, CA 94612
pro**-0
Task Order No.:
Contract No.:
0016
EP-S9-17-03
Location:
COVE CHAPTER
NAVAJO NATION
Date:
3/1 0/2023
HRS Documentation Record
26
Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
Lukachukai Mountains Mining District
NNN000920223
Figure No.:
7
-------
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used by the EPA with Esrrs permission.
HRS Documentation Record
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y Waste Pile
Historic Haul Route
Wash
Note:
AOC Area of concern
References: 43, pp. 3022, 3129; 63, p.64.
1 inch = 800 feet
1:9,600
800 400 0
800
~ Feet
MESA III
BACKGROUND SAMPLE LOCATIONS
\\ /V -.is a<\ u "7T07,0,8
X~\ ) aoo>9 oAjr^ ^
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Prepared For: U.S. EPA Region 9
J&D ST^
Prepared By:
Task Order No.:
0016
Contract No.:
EP-S9-17-03
Location:
COVE CHAPTER
NAVAJO NATION
3/7/2023
| Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
Figure No.:
3
Lukachukai Mountains Mining District
NNN000920223
-------
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The source of this map image is Esri,
used by the EPA with Esri's permission.
• W&ste Sample Location1
E3E3 W&ste Pile
¦ Historic Haul Route
W&sh
Notes:
^Vaste pile boundaries are estimated;
samples that appear to be outside the waste
pile boundaries are representative of waste
from the waste pile.
AOC Area of concern
References: 20, pp.149, 150; 22, p.140; 21,
pp.147, 148, 149.
1 inch = 400 feet
1:4,800
400 200 0
N
W<^s*-E
400
I Feet
MESA IV
WASTE SAMPLE LOCATIONS -
EAST SIDE
Prepared For: U.S. EPA Region 9
^tDsr^
a.
USB,
Task Order No.:
0016
Location:
COVE CHAPTER
NAVAJO NATION
Prepared By:
TETRA TECH
Contract No.:
EP-S9-17-03
3/7/2023
Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
Figure No.:
9
HRS Documentation Record
28
Lukachukai Mountains Mining District
NNN000920223
-------
" flF- .*?* ,A \ »A *
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izza W&ste Pile
¦ Historic Haul Route
Wash
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1'
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Notes:
1Waste pile boundaries are estimated;
samples that appear to be outside the
waste pile boundaries are representative of
waste from the waste pile,
AOC Area of concern
References: 23, p.141; 79, p.22; 76, pp. 42,
43, 44, 45; 77, p.22; 19, p.145; 18, pp.143,
144; 78, p.22.
— oK
<»' &L
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-------
Background Surface Soil Sample Location
0-6 inches
B20-SS12-01 -052318
Background Study Area (BSA)
Waste Pile
Historic Haul Route
Wash
BSA-20
BSA-19 \
B19-SS28-01 -052618
B20-SS25-01 -052318
Area of concern
References: 43, pp.1988, 2091, 2502, 2606.
2709; 63, p.64.
SS-CO-B1-021-10142017
'•v, " r-Jf/
Morrison Formation
OtherPossible Area
BofiGonceFnBf
¦VPPMHBMPHsS
SS-CO-B1 -008-10142017i
1 inch = 800 feet
1:9,600
B25-SS04-01 -060418
MESA IV
BACKGROUND SAMPLE LOCATIONS
B26-SS27-01 -060518
B24-SS06-01 -071618
Prepared For: U.S. EPA Region 9
Prepared By:
TETRA TECH
1999 Harrison Street, Suite 500
Oakland, CA 94612
B24-SS26-01 -071618
Task Order No.
Contract No.
001 6
Location:
COVE CHAPTER
NAVAJO NATION
3/7/2023
Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
Figure No.
The source of this map image is Esri,
used by the EPA with Esrrs permission
-------
mm
SS-04-NNWP01 -002-09202
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BSA-18
M14-XS36-01 -052418
B18-SS25-01 -052518
M13-SS59-01 -091518
^; » «V
B21-SS07-01 -062118
BSA-19
B19-SS28-01 -052618
99
¦PHPH
Morrison Formation
SS-CO-B1 -021 -10142017
SMto—fi
Prepared By:
The source of this map image is Esri,
used by the EPA with Esrrs permission.
Waste Sample Location1
Background Surface Soil Sample Location
0-6 inches
Waste Pile
Background Study Area (BSA)
Historic Haul Route
Wash
Notes:
1Wiaste pile boundaries are estimated;
samples that appear to be outside the
waste pile boundaries are representative of
waste from the waste pile.
AOC Area of concern
References: 17, p.154; 16, pp.144, 145; 42,
p.136; 15, p.140; 13, p.141; 75, p. 22; 14,
p.140; 43, pp. 1885, 1988, 2194, 2296,
2399; 63, p.64.
1 inch = 800 feet
1:9,600 s
800 400 0 800
~ Feet
MESA V AND VI
BACKGROUND AND
WASTE SAMPLE LOCATIONS
Prepared For: U.S. EPA Region 9
^tDST^
m
PROt^
Task Order No.:
0016
Contract No.:
EP-S9-17-03
Location:
COVE CHAPTER
NAVAJO NATION
| Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
3/6/2023
Figure No.:
12
HRS Documentation Record
31
Lukachukai Mountains Mining District
NNN000920223
-------
*K29-SSW01 -01 -072122
208-SSW01 -01 -071922
B32-SS23-01 -071218
467-SSW03-01 -072122
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1 he source of this map image is Esri,
used by the EPA with Esrrs permission
V\faste Sample Location'
Background Surface Soil Sample Location
0-6 inches
Waste Pile
Background Study Area (BSA)
Historic Haul Route
Wiash
Notes:
1V\feste pile boundaries are estimated;
samples that appear to be outside the
waste pile boundaries are representative of
waste from the waste pile.
AOC Area of concern
References: 33, p.137; 186, pp.25, 26, 28,
29; 43, p.3234
1 inch = 800 feet
1:9,600
800 400 0
800
~ Feet
KNIFE EDGE MESA
BACKGROUND AND
WASTE SAMPLE LOCATIONS
Prepared For: U.S. EPA Region 9
^tDsr^
a.
Task Order No.:
0016
Location:
LUKACHUKAI CHAPTER
NAVAJO NATION
Prepared By:
Contract No.:
EP-S9-17-03
3/6/2023
Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
Figure No.:
13
HRS Documentation Record
Lukachukai Mountains Mining District
NNN000920223
-------
M36-XS31 -01 -081218
B33-SS10-01 -071618
B33-SS08-01 -071618
BSA-33
; • M37-XS124A-01'0813i8j
'V
I
^ I
$*. /•
M34-SS109-01-092718
f;yaMaal
' ¦
AOC - 38
M35-XS74-02-081318
I '
. JUOl v/a m
I Hi
M35-XS74-01 -081318
2W"V"' .
J*' II I ¦ o '
s'4:-SSt
y<. gf
' .-'111/ «L'
M "fv1
¦! f«/J
=c, JFslSsia
PE'Jfflw/•-. '• >sk •
;'V*» i
¦ucKr : * 77
\^W?> /rttrv
'V- >' . vfc:
\ * . (5
' - •\s -J
^ i sfta*S*dJr
«Si4/,A
* -.,
* . '*2Sbii
i • v^1
f f «f»H ,;"
>JfeB8fiV'*T trSST-. V. r™
• V\faste Sample Location'
Background Surface Soil Sample Location
0-6 inches
|__j Background Study Area (BSA)
tfeN Waste Pile
Historic Haul Route
" Wash
Notes:
1V\feste pile boundaries are estimated;
samples that appear to be outside the
waste pile boundaries are representative of
waste from the waste pile.
AOC Area of concern
References 34, p.140; 35, p.140; 36, p.140;
37, p.140; 43, pp. 3234, 3342.
1 inch = 660 feet
1:7,920
660 330 0
FLAG MESA
BACKGROUND AND
WASTE SAMPLE LOCATIONS
Prepared For: U.S. EPA Region 9
^tDsr^
a.
I Task Order No.:
The source of this map image is Esri,
used by the EPA with Esrrs permission.
IP-
r
B32-SS23-01 -071218
| Location:
LUKACHUKAI CHAPTER
NAVAJO NATION
Prepared By:
TETRA TECH
Contract No.:
EP-S9-17-03
3/6/2023
| Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
Figure No.:
14
HRS Documentation Record
Lukachukai Mountains Mining District
NNN000920223
-------
200-SSW01 -01 -100422
201;SSW03-01-100422
Other Possible Area
Bfof.ConcernU
202-SSW02-01-100422
202-SSW03-01-100422
M38-SS2-01 -092718
B33-SS10-01 -071618
I
.. '.V®£ / 'Szte jrarPi
> i»r 1 Jr. «7»fc.U£5Pr
r* . t"
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• • .- .W. . ;
/
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^ '•
y&ESr&LJr. '
%sBz&,
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ta? CX.
3.J"~ 'V - Tjj
201-SSW02-02-100422
V: W
bC /
ZyA*$?b" • -*
.v!' .Mr *, y• r ^ESrTiiT'^Bi -xiT^^KTVxV «
»«? ¦
^S'Lav 1
- -
s^k., A,; ^SjjBfe
lap- -J&s&ht
HRS Documentation Record
?WU>
W&ste Sample Location'
Background Surface Soil Sample Location
0-6 inches
Waste Pile
Background Study Area (BSA)
Historic Haul Route
Wash
Notes:
1V\feste pile boundaries are estimated;
samples that appear to be outside the
waste pile boundaries are representative of
waste from the waste pile.
AOC Area of concern
References: 38, p.42; 43, p.3342; 212,
pp.13, 14, 15.
1 inch = 600 feet
1:7,200
600 300 0
STEP MESA
BACKGROUND AND
WASTE SAMPLE LOCATIONS
Prepared For: U.S. EPA Region 9
^tDsr^
Task Order No.:
Location:
LUKACHUKAI CHAPTER
NAVAJO NATION
Prepared By:
TETRA TECH
Contract No.:
EP-S9-17-03
3/7/2023
Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
Figure No.:
15
Lukachukai Mountains Mining District
NNN000920223
-------
MexCry-SSBG-01 -092922
468-SSW02-01-092922
468-SSW01-01-092922
427-SSW01-01-092922,
427-SSW01-02-092922
199-SSW02-01-092922
Prepared For: U.S. EPA Region 9
A,
Prepared By:
The source of this map image is Esri,
used by the EPA with Esrrs permission.
Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
Figure No.:
16
MEXICAN CRY MESA
BACKGROUND AND
WASTE SAMPLE LOCATIONS
Task Order No.:
0016
Contract No.:
EP-S9-17-03
Location:
NAVAJO NATION
3/6/2023
• Waste Sample Location1
Background Surface Soil Sample Location
0-6 inches
ESI W&ste Pile
¦—— Historic Haul Route
Wash
Notes:
Vi&ste pile boundaries are estimated;
samples that appear to be outside the
waste pile boundaries are representative of
waste from the waste pile.
AOC Area of concern
References: 213, pp.16, 17, 19, 20, 21.
1 inch = 540 feet
1:6,480 |
540 270 0 540
~ Feet
HRS Documentation Record
Lukachukai Mountains Mining District
NNN000920223
-------
mm
¦¦¦ppi
472-SSW03-01 -071822
COVE-BKG-01
AOC-51
<*¦ 'y (
472-SSW02-01 -071822
B7-SS19-01-052218
Residence 2
Cove Transfer Station
Residence 1
T9-XS93-01 -042518 (AOC - 50)
T9-XS61 -01 -042518 (AOC - 50)
PMMMHttMMM
472-SSW04-01-072022 (AOC -
472-SSW12-01-072022 (AOC - 49)
B6-SS07-01 -052218
472-SSW06-01-072022
Cove Day School
The source of this map image is Esri,
used by the EPA with Esri's permission
• Waste Sample Location
Background Surface Soil Sample Location
0-6 inches
y Waste Pile
Background Study Area (BSA)
Historic Haul Route
Wash
Notes:
AOC Area of concern
References: 40, p.167; 43, pp. 637, 741;
73, p. 2150, 2151, 2153, 2154, 2155.
1 inch = 1,200 feet
1:14,400
1,200 600 0
N
S
1,200
~ Feet
COVE TRANSFER STATION
BACKGROUND AND
WASTE SAMPLE LOCATIONS
Prepared For: U.S. EPA Region 9
a.
Task Order No.:
0016
Location:
LUKACHUKAI CHAPTER
NAVAJO NATION
Prepared By:
TETRA TECH
1999 Harrison Street, Suite 500
Oakland, CA 94612
Contract No.:
EP-S9-17-03
3/1 0/2023
Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
Figure No.:
17
HRS Documentation Record
Lukachukai Mountains Mining District
NNN000920223
-------
Cove Mesa Mines (Cato Sells) - 35
Cove Mesa Mines (Cato Sells) - 36 -
&&%£? ' - \£ t&t$M
Cove Mesa Mines (Cato Sells) - 34
nM-n
Cove Mesa Mines (AEC Lease Plot 7) - 37
Cove Mesa Mines (AEC Lease Plot 7) - 431
Red Valley
Chapter
Chapter
rt •L
Sweetwater/Tolikan
Chapter
Cove Mesa Mines (AEC Lease Plot 7) - 38
S ' \, -w * " I *#
Cove Mesa Mines (AEC Lease Plot 7) - 501
Round Rock
Chapter
mmwa
Cove Mesa Mines (AEC Lease Plot 7) - 39
'N'"x
Cove Mesa Mines (AEC Lease Plot 7) -
v v ^
n m
— V " ^ ¦- V
V L
V 4L.
Cove Mesa Mines (AEC Lease Plot 7) - 430
— Cove Mesa Mines I
%* V
«qjl
tm
- A
*- * f
li ¦Nihil' j
HH
Cove Mesa Mines (AEC Lease Plot 7)^497;
East Mesa Mines
West Mesa
Mine
¦M&&
afriyr
y
pH-J
Cove
t source of this map image is Esri,
used by the EPA with Esri's permission.
=
(AEC
Lease P o
Area
-*
; Detail
I f" ^ / >
>
~ Lukachukai Mountains Mining District
Mines / Other Sources1
Cove Mesa
Cove Transfer Station
East Mesa
Flag Mesa
Knife Edge Mesa
Mesa I
Mesa I!
Mesa III
Mesa IV
Mesa V and VI
Mexican Cry Mesa
Step Mesa
West Mesa
~ Navajo Nation Boundary
I J Navajo Nation Chapter Boundary
Hopi Reservation
Historic Haul Route
Wash
Cove Day School
Note:
Reference 71.
1 inch - 3,400 feet
1:40,800
3,400 1,700 0
COVE MESA, EAST MESA,
AND WEST MESA OTHER POSSIBLE
AREAS OF CONCERN
Cove
Day
Schoo
Prepared For: U.S. EPA Region 9
My j. t
Task Order No.:
Location:
NAVAJO NATION
Prepared By:
TETRA TECH
Contract No.:
EP-S9-17-03
1/1 2/2023
Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
Figure No.:
18
HRS Documentation Record
Lukachukai Mountains Mining District
NNN000920223
-------
Other Possible AOC 3
036-SSW01 -01 -100122,
036-SSW02-01 -100122,
036-SSW03-01 -100122
COVE-SSBG02-01 -100322
• Other Possible AOC 2
.037-SSW01 -01 -100122,
\037-SSW02-01 -100122
034-SSW01 -01 -100322, 034-SSW02-01 -100322
037-SSW03-01 -100122
Other Possible AOC 1
038-SSW03-01-100322
Other Possible AOC 4
Other Possible AOC 5
Other Possible AOC 12
038-SSW02-01 -100122
Other Possible AOC 8
431-SSW01 -01 -100122
501-SSW03-Q1 -100122
Other Possible AOC 12
Other Possible AOC 12
Other Possible AOC 7
430-SSW01 -01 -100122
430-SSW02-01 -100122
430-SSW03-01 -100122
501-SSW01 -01 -100122,
501-SSW02-01 -100122
Other Possible AOC 12
039-SSW01 -01 -100122.
039-SSW02-01 -100122
Other Possible AOC 10
039-SSW03-01 -100122
497-SSW02-01-093022
Other Possible AOC 6
497-SSW01 -01
498-SSW03-01-093022
Other Possible AOC 10
Other Possible AOC 11
Other Possible AOC 13
493-SSW01
493-SSW02-01-093022
Cove-SSBG-01-093022
040-SSW01-01-093022
The source of this map image is Esri,
used by the EPA with Esrrs permission.
• Waste Sample Location1
Background Surface Soil Sample Location
0-6 inches
ESI \Naste Pile
¦—— Historic Haul Route
Wash
Notes:
'Waste pile boundaries are estimated;
samples that appear to be outside the
waste pile boundaries are representative of
waste from the waste pile.
AOC Area of concern
References: 214, pp.30, 31, 32, 33, 35, 36,
37, 38, 39, 41, 42, 43.
1 inch - 2,400 feet
1:28,800
2,400 1,200 0
N
S
2,400
Feet
COVE MESA
BACKGROUND AND
WASTE SAMPLE LOCATIONS
Prepared For: U.S. EPA Region 9
Prepared By:
It
TETRA TECH
1999 Harrison Street, Suite 500
Oakland, CA 94612
pro**-0
Task Order No.:
Contract No.:
0016
EP-S9-17-03
Location:
Date:
NAVAJO NATION
3/6/2023
Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
Figure No.:
19
HRS Documentation Record
38
Lukachukai Mountains Mining District
NNN000920223
-------
Colorado
Arizona
[New Mexico
W ; ¦# r..: ~ 0
^ I ^
-f
;r v 1 . : |c
»/£ . \Jr 3.?/ -" /¦ V &
V. Jg Maw,™* jm. |> ¦'•¦
fip^^rvsl ••• , m m^'"—-
SBt&rd ¦ l4BfcvJM. *&&&¦'• M; ".V SBI
0*K :'.x
>&•.
28SBN£gH
I-.'
w » '•• '.'.« •' X'-.p . - ¦^ :A '
, >•' 80 •'I -vTiV "J & "¦ v • "4VV->.'^V '••- '
¦ v'li.m
' ' \ - ' ' •
*o4 " & ;'Mf;
bfed£5 > 2u*wf
.^¦Mi
MS
HI '
* *
«¦>*
The source of this map image is Esri,
used by the EPA with Esri's permission
B Lukachukai Mountain Mining District
MSO Potential Nesting Habitat Buffer (0.25 miles)
Protected Activity Centers
2009
2018
Mines / Other Sources
Cove Transfer Station
Flag Mesa
Knife Edge Mesa
Mesa I
Mesa II
Mesa III
Mesa IV
Mesa V and VI
Mexican Cry Mesa
Step Mesa
~ Navajo Nation Boundary
| ] Navajo Nation Chapter Boundary
iX'xSj Hopi Reservation
Historic Haul Route
V\fesh
Well (Domestic Use)
Cove Day School
Notes:
MSO Mexican spotted owl
References: 71, p.56; 72, p.20
1 inch = 3,400 feet
1:40,800
s
3,400 1,700 0 3,400
~ Feet
LUKACHUKAI MOUNTAINS
MINING DISTRICT ¦
MEXICAN SPOTTED OWL
PROTECTED ACTIVITY CENTERS
AND BUFFERS
Prepared For: U.S. EPA Region 9
^tDsr^
a.
Prepared By:
Task Order No.:
0016
Contract No.:
EP-S9-17-03
Location:
NAVAJO NATION
Coordinate System:
NAD 1983 State Plane Arizona East
FIPS 0201 Feet Transverse Mercator
3/6/2023
Figure No.:
20
HRS Documentation Record
Lukachukai Mountains Mining District
NNN000920223
-------
SITE DESCRIPTION
The Lukachukai Mountains were the location of a post-World War II and Cold War uranium and vanadium
mining district operated by a series of mining companies under numerous mine claims and leases between 1949
and 1968 (see Figures 1 to 3) (Ref. 187, p. 34-53). The Lukachukai Mountains Mining District (LMMD) site is
situated primarily in the Cove, Round Rock, and Lukachukai Chapters of the Navajo Nation in northeast Arizona.
The HRS score for the LMMD site is based on 51 Areas of Observed Contamination (AOC) (see Figures 1, 4 to
17), comprising waste piles and contaminated soil throughout the LMMD site, scored under the soil exposure
component of the soil exposure and subsurface intrusion pathway (see the table of AOCs at the end of this site
description). The Navajo Nation supports the placement of the LMMD site on the NPL (Ref. 217).
"Lukachukai" is a Navajo word meaning "patches of white reeds" and refers to the many lakes occurring on the
main flat-topped ridge of the mountains. The elevation of this ridge is about 8,800 feet above sea level, but
isolated ridges rise as much as 100 feet higher. The Lukachukai Mountains trend northwestward, connect with the
Carrizo Mountains to the northwest, and, except where they join with the Chuska Mountains to the southeast,
terminate as precipitous cliffs on either side. Finger-like mesas and deep, steep-walled canyons combine to form
very rugged topography. The finger-like mesas are not true mesas but were named and numbered as such by
personnel of the U.S. Atomic Energy Commission (AEC) in late 1950. The prominent mesas on the north side of
the mountains are numbered I through VII toward the northwest terminus at Mexican Cry Mesa. The southside
mesas bear such descriptive names at Two Prong, Camp, Cisco, Three Point, Knife Edge, Bare Rock, Flag, Step,
Fall Down, and Thirsty. In general, the mine claims are named for the mesas on which they occur and minor
divisions such as Mesas I 1/2,1 3/4, II 1/2 and IV 1/2 do occur on the north side (Ref. 187, p.9).
Carnotite (uranium-vanadium ore) was discovered around 1918 in the Carrizo Mountains, north of the
Lukachukai Mountains, and many mining claims were filed within the Carrizo and neighboring Lukachukai
Mountains during the next few decades. The carnotite deposits are in the Salt Wash sandstone member of the
Morrison Formation. The ore deposits consist of sandstone impregnated with carnotite and a vanadium-bearing
mica. In general, the deposits tend to form clusters in ill-defined areas. The deposits are believed to have formed
from groundwater solutions shortly after the accumulation of the enclosing sands (Ref. 188, pp.3,4).
Mine claims were given unique mine names based on the mesa where the claim was located to track ore
extraction from specific claims throughout the LMMD site. These unique mine claim names became associated
with individual LMMD surface features and are often referred to as abandoned uranium mines (AUM) by past
and current USEPA and Navajo Nation Environmental Protection Agency (NNEPA) inventory and investigation
efforts. Mining of uranium deposits in the Lukachukai Mountains commenced in 1950 and continued until 1968
(Ref. 187, pp.6,45). While some individual "one-off claims with no corporate successor are scattered throughout
the LMMD site, most claims were explored and mined by a sequence of three companies (Ref. 210, pp. 1-4):
• Kerr-McGee Oil Industries, Inc. (Kerr-McGee) (later Tronox)
• Vanadium Corporation of America (VCA) (later Cyprus Amax Minerals Company [Cyprus Amax], a
wholly owned subsidiary of Freeport-McMoRan)
• Foote Mineral Company (later merged with Cyprus Amax)
A few other mines were concurrently explored and mined by the Climax Uranium Company. Foote Mineral
Company and Climax Uranium Company were either acquired or merged into Cyprus Amax in 1988 and 1993,
respectively (Refs. 193, p.6; 199, p.3; 209, p.2).
Kerr-McGee acquired mineral rights on properties in the Lukachukai Mountains in 1952 and was the leading
producer of uranium until 1963, at which time VCA acquired its holdings (Ref. 187, p.6). The Climax Uranium
HRS Documentation Record
40
Lukachukai Mountains Mining District
NNN000920223
-------
Company, a subsidiary of American Metals Climax, Inc., began prospecting in the Lukachukai Mountains about
1950 (Ref. 189, p. 12). A total of 666,850 tons of uranium ore was mined in the Cove Chapter alone (Ref. 65,
p.ll).
The dominant mining methods in LMMD consisted of underground room and pillar, open stoping, incline shafts,
and vertical shafts, resulting in waste piles comprising remnant overburden, protore, and other contaminated
material. Some shallow or exposed ore bodies were successfully mined by rimstripping, trenching, and open pit
methods (Ref. 191, p. 3). Because of the relatively shallow presence of the Morrison Formation and accessibility
from cliff sides, many adits, portals, and surface-mining features were created to remove underground ore rather
than a single portal as was used with deeper ore bodies (Refs. 187 p.46; 189 p.21; 208 p.33). Underground mining
followed the uranium-vanadium-rich carnotite ore deposits, often resulting in underground connections of
workings through multiple adits or portals.
The rugged topography made road building difficult and hazardous. Roads, ore transfer stations, and other
infrastructure were owned, operated, or used collectively by LMMD mining companies and used by the other
one-off mine claimants, interconnecting mining activities into one large mining operation throughout the mining
district. Figure 2 shows the primary haul roads and drill trails that connect the various mine claims and ore
extraction points throughout the LMMD site. Figure 2 also shows the sample locations where site-related
contaminants were detected above background on the roads from spillage and road construction, maintenance, and
use. Migration of waste from the waste piles has also resulted in comingled contamination in washes and
drainages, surface water, and groundwater (Refs. 64, pp. 9,17; 65, p. 95). Figure 3 shows the primary drainages
and surface water bodies emanating from the various AOCs and flowing through the Cove Valley below
(Ref.207, pp. 19-21). Figure 3 also shows sediment sample locations where site-related contaminants were
detected above background as a result of mine waste migration (Refs. 73, p. 10; 206, p. 10; 62, p. 151; 65, p. 95;
207, pp. 19-21). More than 800,000 cubic yards of mine waste remains in waste piles and significant migration of
waste has already occurred downgradient of mesas throughout surface water drainages in the LMMD (Ref. 62, p.
147).
In the 1980s through 2000s, the Navajo Abandoned Mine Lands (NAML) Program inventoried, assessed, and
reclaimed the physical safety hazards associated with the AUM features in the LMMD site through funding and
authority provided by the Surface Mine Closure and Reclamation Act (SMCRA). NAML inventory efforts
assigned a series of numbers (commonly starting with "NA-" or Navajo Area). The numbering system is
connected to problem areas identified by NAML during the SMCRA-approved inventory process—the LMMD
site is in the Cove Abandoned Mine Land Problem Area, NA-0300s series. All accessible adits and portals within
the LMMD were closed with the most feasible methods available at the time of the reclamation work. Waste piles
accessible by heavy equipment underwent NAML reclamation and were renamed and renumbered as burial cells.
The reclamation actions were not intended to fully address contamination, and all burial cells contain surficial
contamination above background levels as evidenced by subsequent investigations. The burial cells are piles of
waste moved from other locations and buried with 1.5 feet of borrow material, which meets the definition of a pile
according to HRS definitions (Ref. 65, pp. 14, 71-76, 221-227). The cover material is less than 2 feet thick by
design (Refs. 65, p. 226; 223, p. 20). No wastes were removed from the LMMD site as a result of reclamation
actions (Refs. 65, pp. 14, 71-76, 221-227; 223, p.20).
In 2018, USEPA in coordination with NNEPA conducted an extensive removal site evaluation (RSE) under
CERCLA. The RSE field effort included characterization of 39 AUMs, 37 AUM-related areas of suspected
contamination, 22 miles of surface water drainages, nearly 10 miles of access roads, and 32 background study
areas, each approximately 'A acre in area (Ref. 62, pp. 12, 16). Nine additional AUM areas in the LMMD site
were investigated by Cyprus Amax in 2017 and reported in an RSE report in 2022 (Ref. 63, p. 15). This HRS
documentation record is based primarily on the data resulting from these RSEs.
HRS Documentation Record
41
Lukachukai Mountains Mining District
NNN000920223
-------
The Lukachukai and greater Chuska Mountains are heavily used by the Navajo people for hunting, plant
gathering, and livestock grazing and provide habitat for several sensitive species, including the federally
threatened Mexican spotted owl (Strix occidentalis lucida) (Refs. 66; 67; 72, p. 17). The Lukachukai Mountains
are in an area that, while relatively small in size, is important to the maintenance of a unique biotic community
used by the Navajo people for cultural, ceremonial, and medicinal purposes. Many ceremonial and medicinal
plants and animals in the Lukachukai Mountains exist only in this area (Ref. 66). The Lukachukai Mountains also
provide habitat for a dense aggregation of large vertebrates that provides unique hunting opportunities on the
Navajo Nation (Ref. 67). Intermittent streams draining the Lukachukai Mountains, particularly the Cove Wash
Watershed complex, are extensively contaminated by eroded waste from AUMs (Ref. 65, pp. 88-96). Wetlands
along the Cove Wash headwater drainages support unique biotic communities in isolated pockets (Ref. 219). The
community of Cove supports a residential population of approximately 400, and just under 50 children from the
community attend the Cove Day School, which is located within an area of contaminated soil associated with a
former ore transfer station (Refs. 65. p. 19; 70).
Tsihle 1. Siiiniiiiirv ol' AOC s
AOC
No.
AOC
Typo
AOC Location
\\ :isle l*iIt* or Minc-Kclsilcd Area Nsimcs
1
Pile
Mesa I
Waste Pile M3
2
Pile
Mesa I
Waste Pile M4; Burial Cell 9
3
Pile
Mesa I
Waste Piles M5A, M5B, and M5C
4
Pile
Mesa I
Waste Pile M6
5
Pile
Mesa I
Waste Piles M7A, M7B, and M7C
6
Pile
Mesa I
Waste Piles M8A and M8B; Burial Cells 6a, 6b, and 7
7
Pile
Mesa I
Waste Piles T17A and T17B; Burial Cell 310AB
8
Pile
Mesa I
Waste Pile M9
9
Pile
Mesa I
Waste Piles Ml OA and Ml 0B
10
Pile
Mesa II
Waste Pile M12
11
Pile
Mesa II
Waste Pile M25; Burial Cells 3 la and 3 lb
12
Pile
Mesa II
Waste Piles M27 and M28; Burial Cell 39
13
Pile
Mesa II
Waste Piles M29A and M29B; Burial Cell 43
14
Pile
Mesa II
Waste Pile M24; Burial Cell 44
15
Pile
Mesa II
CO-07 NNWP01 and CO-07 NNWP02
16
Pile
Mesa II
Waste Pile Mil
17
Pile
Mesa II
CO-03 CAWP01
18
Pile
Mesa III
Waste Pile M30; Burial Cell 48
19
Pile
Mesa III
Waste Piles M31 and M32
20
Pile
Mesa III
CO-08 CAWP01
21
Pile
Mesa III
CO-09 NNWP01
22
Pile
Mesa IV
Waste Piles M20A, M20B, M22A, M22B, M22C; Burial Cell 56
23
Pile
Mesa IV
Waste Piles M21A, M21B, M21C, M21D, M21E, and M21F;
Burial Cell 63
24
Pile
Mesa IV
Waste Pile M23; Burial Cell 70b
25
Pile
Mesa IV
CO-10 NNWP01
26
Pile
Mesa IV
CO-05 NNWP14, CO-05 NNWP15. CO-05 NNWP16, CO-
05 NNWP17, CO-05 NNWP18, and CO-05 NNWP19, CO-
05 NNWP05, CO-05 NNWP06, CO-05 NNWP07, CO-
05 NNWP08, CO-05 NNWP09, CO-05 NNWP10, CO-
05 NNWP 11, CO-05 NNWP 12, and CO-05-NNWP 13, CO-
HRS Documentation Record
42
Lukachukai Mountains Mining District
NNN000920223
-------
Tsihle 1. Siiiniiiiirv of AOCs
AOC
No.
AOC
Typo
AOC Location
Wsisle I'ile or Mine-Uehiletl Aresi Nsimes
05 NNWP01, CO-05 NNWP02, CO-05 NNWP03, and CO-
05_NNWP04, CO-06_NNWP01; Waste Piles Ml8 and Ml9;
Burial Cells 86b and 87a
27
Pile
Mesa IV
CO-11 NNWP01, CO-11 NNWP02, and CO-11 NNWP03
28
Pile
Mesa IV
Cov087 Waste Pile
29
Pile
Mesa V & Mesa VI
Waste Piles M15A, M15B, M16A, M16B, and M17; Burial Cells
91, 92, 93, and 344B-2
30
Pile
Mesa V & Mesa VI
Waste Piles M13A and M13B
31
Pile
Mesa V & Mesa VI
CO-04 NNWP01
32
Pile
Mesa V & Mesa VI
Waste Pile M14
33
Pile
Knife Edge Mesa
Waste Pile M33
34
Pile
Knife Edge Mesa
Waste Pile M52
35
Pile
Knife Edge Mesa
Waste Pile M53A and M53B
36
Pile
Knife Edge Mesa
Waste Pile M54
37
Pile
Flag Mesa
Waste Piles M37A and M37B
38
Pile
Flag Mesa
Waste Piles M34A and M34B
39
Pile
Flag Mesa
Waste Piles M35A, M35B, M35C, and M36
40
Pile
Step Mesa
Waste Pile M38
41
Pile
Step Mesa
Jimmie King No. 9 Waste Pile
42
Pile
Step Mesa
NA-0332 Waste Pile
43
Pile
Step Mesa
NA-0333 Waste Pile
44
Pile
Mexican Cry Mesa
Mexican Cry 197 Waste Pile
45
Pile
Mexican Cry Mesa
Mexican Cry 198 Waste Pile
46
Pile
Mexican Cry Mesa
Hall Mine Waste Pile
47
Pile
Mexican Cry Mesa
Nakai Chee Begay Waste Pile
48
Pile
Mexican Cry Mesa
Tom Joe No. 6 Waste Pile
49
Contam.
Soil
Cove Transfer
Station
Cove Day School yard contaminated soil
50
Contam.
Soil
Cove Transfer
Station
Residence 1 contaminated soil
51
Pile
Cove Transfer
Station
CTS2 Stockpile
Several Other Possible AOCs on Cove Mesa, East Mesa, and West Mesa are described later in this HRS
documentation record. Each of these Other Possible AOCs has been sampled and found to be contaminated with
the same contaminants as the scored AOCs (see Figures 18 and 19). These other possible AOCs are:
Tsihle 2. Oilier Possible AOCs on Co\e Messi. K:isl Messi. :incl West Messi
Nil m her
Locution
Mine ( hiini Nsimes
Other Possible AOC 1
Cove Mesa
Cove Mesa Mines (Cato Sells 34)
Other Possible AOC 2
Cove Mesa
Cove Mesa Mines (Cato Sells 35)
Other Possible AOC 3
Cove Mesa
Cove Mesa Mines (Cato Sells 36)
Other Possible AOC 4
Cove Mesa
Cove Mesa Mines (AEC Lease Plot 7) - 37
Other Possible AOC 5
Cove Mesa
Cove Mesa Mines (AEC Lease Plot 7) - 38
HRS Documentation Record
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Lukachukai Mountains Mining District
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1 'sihle 2. Oilier Possible AOC's on Co\e Messi, K:isl Messi. :incl West Messi
Nil m her
Location
Mine Chiini Nsimes
Other Possible AOC 6
Cove Mesa
Cove Mesa Mines (AEC Lease Plot 7) - 39
Other Possible AOC 7
Cove Mesa
Cove Mesa Mines (AEC Lease Plot 7) - 430
Other Possible AOC 8
Cove Mesa
Cove Mesa Mines (AEC Lease Plot 7) - 431
Other Possible AOC 9
Cove Mesa
Cove Mesa Mines (AEC Lease Plot 7) - 434
Other Possible AOC 10
Cove Mesa
Cove Mesa Mines (AEC Lease Plot 7) - 497
Other Possible AOC 11
Cove Mesa
Cove Mesa Mines (AEC Lease Plot 7) - 498
Other Possible AOC 12
Cove Mesa
Cove Mesa Mines (AEC Lease Plot 7) - 501
Other Possible AOC 13
East Mesa
East Mesa Mines
Other Possible AOC 14
West Mesa
West Mesa Mine
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5.0
SOIL EXPOSURE AND SUBSURFACE INTRUSION PATHWAY
5.0.1 EXPOSURE COMPONENTS
Component being scored: soil exposure component.
5.1 SOIL EXPOSURE COMPONENT
The soil exposure component is scored based on 51 areas of observed contamination (AOCs) resulting from a
mining operation in the LMMD site that extracted ore from the Salt Wash Member of the Lower Morrison
Formation. The AOCs are all mine waste piles (49 AOCs) and associated contaminated soil (2 AOCs) with
similar waste characteristics. All AOCs are interconnected by mining-impacted haul roads, common usage of ore
transfer stations, and contamination that has migrated from the AOCs to intermittent or ephemeral streams (also
called drainages) (see Figures 2 and 3). Further investigation is necessary at eight additional areas of concern
located between and near scored AOCs, including additional waste piles and contaminated soil.
To facilitate the review of this HRS documentation record, descriptions and data used in HRS scoring are grouped
geographically by the following LMMD mesas and the Cove Transfer Station (see Figure 1):
1. Mesa I (nine AOCs)
2. Mesa II (eight AOCs)
3. Mesa III (four AOCs and two other areas of concern)
4. Mesa IV (seven AOCs and one other area of concern)
5. Mesa V and Mesa VI (four AOCs and four other areas of concern)
6. Knife Edge Mesa (four AOCs and one other area of concern)
7. Flag Mesa (three AOCs)
8. Step Mesa (four AOCs and one other area of concern)
9. Mexican Cry Mesa (five AOCs)
10. Cove Transfer Station (three AOCs)
In addition to the AOCs and associated areas of concern, 14 "Other Possible AOCs" exist on nearby Cove Mesa,
East Mesa, and West Mesa. These Other Possible AOCs meet the observed contamination criteria and are
described in more detail at the end of Section 5.1.0.
5.1.0 GENERAL CONSIDERATIONS
The analytical data used to score the following AOCs was collected under USEPA approved sampling Work
Plans, which included Sampling and Analysis Plans, Quality Assurance Project Plans, and Field Sampling Plans
(Refs. 93; 221; 222). USEPA and Navajo EPA reviewed these Work Plans to ensure consistency in sampling and
analysis methodology (Refs. 93; 221; 222). The separate RSE data collection efforts were performed using
comparable methodologies.
In 2018, USEPA in coordination with NNEPA conducted an RSE under CERCLA (Ref. 221, p. 11). The RSE
included characterization of 39 AUMs, 37 AUM-related areas of suspected contamination, 22 miles of surface
water drainages, nearly 10 miles of access roads, and 32 background study areas, each approximately 'A acre in
area (Refs. 62, pp. 12,16; 221, pp. 11,14). Nine additional AUM areas in the LMMD site were investigated by
Cyprus Amax in 2017 and reported in an RSE report dated October 2022 (Refs. 63, p. 15; 222, pp. 7,8,9). USEPA
and Navajo EPA reviewed the Cyprus Amax sampling Work Plan to ensure that the sampling and analysis
procedures were consistent with those used by USEPA (Ref. 199, p. 117). In 2022, USEPA conducted additional
sampling of previously unsampled AOCs in 2022 following the 2018 Work Plan (Refs. 93; 221).
HRS Documentation Record
45
Lukachukai Mountains Mining District
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All but two of the AOCs evaluated in this section are waste piles. To clarify terminology used in other reports, the
term "Burial Cells" refers to a waste pile created by reclamation activities performed by the Navajo Abandoned
Mine Lands Program (Ref. 65, p. 11). The term burial cell was used by investigators to differentiate un-reclaimed
waste piles from those reclaimed by NAML (Ref. 65, pp. 11,62,98). NAML's priority was to reclaim physical
safety hazards, not to clean up the contamination at the mines (Ref. 65, p. 11). NAML often moved mine waste
from un-reclaimed waste piles to cover physical hazards such as portals or highwalls, creating new waste piles
also known as burial cells (Ref. 223, pp. 20-22). Burial cells were typically covered with "Class A" material to a
depth of 18 inches (Refs 65, p. 62; 223, p. 22). Class A material was intended to be material from mine waste
piles, overburden, subsoil, topsoil or other suitable backfill material with Ra-226 concentration equal to or less
than the average Ra-226 concentration of the background area in the immediate vicinity (Ref. 223, p. 18).
Recent investigations of burial cells have found contamination significantly above background in surface waste
within the top 6 inches, indicating that any remaining Class A cover either contained hazardous substances above
background at the time of reclamation or has subsequently been eroded or removed from the surface of the burial
cells. All reclamation work performed by NAML was completed by 2004 (Ref. 65, p. 74).
Areas of Observed Contamination 1 through 9 - Mesa I
Nine AOCs are scored as a result of mining activities at Mesa I. The AOCs comprise waste piles created from a
mining operation that extracted uranium ore from eight named mine claims: Mesa I Mine 10, Mesa I Mine 11,
Mesa I Mine 12, Mesa I Mine 13, Mesa I Mine 14, Mesa I Mine 15, Mesa I 1/4 Mine, and Mesa I 1/2 Mine (Refs.
4, p.26; 5, p.27; 6, p.26; 7, p.27; 8, p.27). An additional AOC waste pile is located at the Mesa I Camp, which was
used early on as a staging area for field operations for exploration at the LMMD site (Refs. 4, p.26; 41, p.26).
Mesa I Camp was established by F.A. Sitton in 1950 and used until 1954 when operations were moved to an area
near the Cove Day School now known as the Cove Transfer Station (Ref. 41, p.26). Mesa I Camp is the location
of a waste pile comprising consolidated waste moved by the Navajo Abandoned Mine Lands program in the
2000s.
Table 3. Mesa 1 AOCs
AOC
No.
AOC Type
Mine/Claim Name
RSK Waste I'ile Names
1
Pile
Mesa I Mine 10
Waste Pile M3
2
Pile
Mesa I Mine 11
Waste Pile M4; Burial Cell 9
3
Pile
Mesa I Mine 12
Waste Piles M5A, M5B, and M5C
4
Pile
Mesa I Mine 13
Waste Pile M6
5
Pile
Mesa I Mine 14
Waste Piles M7A, M7B, and M7C
6
Pile
Mesa I Mine 15
Waste Piles M8A and M8B; Burial Cells 6a, 6b, and 7
7
Pile
Mesa I Camp
Waste Piles T17A and T17B; Burial Cell 310AB
8
Pile
Mesa 11/4 Mine
Waste Pile M9
9
Pile
Mesa 11/2 Mine
Waste Piles Ml OA and Ml 0B
The mine claims were developed and operated in the 1950s and 1960s by F.A. Sitton, the Navajo Uranium
Mining Company, Kerr-McGee (a predecessor of Tronox), and VCA (Refs. 4, p.26; 5, p.27; 6, p.26; 7, p.27; 8,
p.27). Operations included underground mining that tapped paleochannels in the Salt Wash Member of the Lower
Morrison Formation that are rich in uranium and vanadium (Refs. 4, p.24; 5, p.24; 6, p.23; 7, p.24; 8, p.24; 9,
p.22; 10, p.22; 41, p.23). Underground mine workings exist throughout Mesa I. The scored AOCs consist of waste
piles of overburden or lower grade protore discarded near or downslope of portals, and waste that has been pushed
or has migrated downslope into drainages (Refs. 3, pp.23,29; 4, pp.22,28; 5, pp.23,29; 6, pp.22,28; 7, pp.23,29; 8,
pp.23,29; 9, pp.21,26; 10, pp.21,26; 41, pp.22,28).
HRS Documentation Record
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Lukachukai Mountains Mining District
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Number by which this AOC is to be identified: 1
Name of AOC: Mesa I Mine 10 Waste Pile M3
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 4
AOC 1 comprises one waste pile: Mesa I Mine 10 Waste Pile M3. The waste in AOC 1 is the byproduct of mine
operations in ore deposits within the Salt Wash Member of the Lower Morrison Formation (Ref. 3, p.24). This
waste pile is 5 to 10 feet deep with a slope ranging from 11 to 54 degrees. AOC 1 is highly erodible, and offsite
migration has been documented and most likely flows down to the Cove Wash Middle 3F drainage located north
of the mine (Ref. 3, p.32). Surficial contamination documented in the AOC sample results below shows that the
waste pile does not have a continuous cover of 2 feet or greater. Mesa I Mine 10 is adjacent to Mesa I Mine 13
(Ref. 3, p.25).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels.
Background levels are determined based on the highest analyte-specific background concentration from the AOC-
specific background study area (Refs. 3, p.35; 43, p. 1382, 1384; 200 p.l). For surface waste samples analyzed for
metals, observed contamination is established when the metal concentration is three times the highest site-specific
background concentration.
BSA-13 was selected as the most appropriate background location for AOC 1 because it is within the same
geologic unit (lower Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC
(Ref. 43, pp.45,46,1362,1365). The highest background concentration for each metals analyte from the 30
samples comprising BSA-13 was used as the background level for AOC 1 (Ref. 43, pp. 45,46,1385). The metals
analysis was performed by ALS Environmental Laboratories using USEPA method SW-846 6020A inductively
coupled plasma mass spectrometry (ICP-MS) (Refs. 87, pp.2,58; 88, p. 6; 87, p. 6; 150, p.2,27).
Table 4. Sample Description and Analytical Results lor AOC 1
Sample II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a nee
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Backgrount
Sample (BSA 13)
3, P-35; 43,
pp.1382,
1384
B13-SS20-
01-071518
0-6"
Silty
sand
1807350-23
7/15/18
Arsenic
(mg/kg)
2.0
0.23
43, pp.6884,
6885,6689;
88, pp.6,65;
220, p.361,
362
B13-SS23-
01-071518
0-6"
Silty
sand
1807350-26
7/15/18
Uranium
(mg/kg)
0.85
0.011
43, pp.6884,
6885,6689;
88, pp.6,71;
220, pp.361,
362
HRS Documentation Record
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Lukachukai Mountains Mining District
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Table 4. Sample Description and Analytical Results lor AOC 1
Sample II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilons
Sn list a nee
1 la/arilons
Substance
Cone.
Reporting
Limit2
Reference
AOC Sample - Mesa
Mine 10 Waste Pile IV
3
M3-XS36-
01-043018
0-3"
Sandy
silt
loam
1805042-2
4/30/18
Arsenic
(mg/kg)
8.2
0.19
150, p.27;
87, p.6; 220,
pp.10, 11
M3-SS36-
01-091618
0-6"
Sandy
silt
loam
1809428-10
9/16/18
Uranium
(mg/kg)
86
0.01
3, p.186; 87,
pp.6,58;
220, p.863
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions (Refs. 1, Section 1.1.; 25, p. 2-47).
Number by which this AOC is to be identified: 2
Name of AOC (Source Type): Mesa I Mine 11 Waste Pile M4 and Burial Cell 9 (Pile)
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 4
AOC 2 comprises two aggregated waste piles of the same waste material: Mesa I Mine 11 Mine Waste Pile M4
and Burial Cell 9. The waste in AOC 2 is the byproduct of mine operations in ore deposits within the Salt Wash
Member of the Lower Morrison Formation (Ref. 4, p.23). Waste Pile M4 and Burial Cell 9 are close to one
another in the central and northwestern portions of the Mesa I Mine 11 Mine (Ref. 4, pp.32,33). Waste Pile M4 is
3 to 4 feet deep and located on a slope greater than 30 degrees in places (Ref. 4, p.32). Burial Cell 9 is well
vegetated (Ref. 4, p.32). The primary waterway drainage at the mine runs through Waste Pile M4. The waste pile
is highly erodible and likely acts as a source for the transport of waste material downslope into the canyon below
where the Cove Wash Middle 3 drainage lies (Ref. 4, pp.22,24). Surficial contamination documented in the AOC
sample results below shows that the waste piles do not have a continuous cover of 2 feet or greater. The workings
for Mesa I Mine 11 extend into the adjacent Mesa I Mine 15 area (Ref. 4, pp.24,25,27,28).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs: 4, p.35; 43, p.960). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
BSA-9 was selected as the most appropriate background location for AOC 2 because it is within the same
geologic unit (Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC (Ref. 43,
pp. 45,46,940,943). The highest background concentration for each metals analyte from the 30 samples
HRS Documentation Record
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Lukachukai Mountains Mining District
NNN000920223
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comprising BSA-9 was used as the background level for AOC 2 (Ref. 43, p. 963). The Ra-226 mean plus two
standard deviations from the 30 samples comprising BSA-9 was used as the background level for AOC 2 (Refs
43, pp. 966; 200, p.2). The metals analysis was performed by ALS Environmental Laboratories using USEPA
method SW-846 6020A ICP-MS (Refs. 89, pp.2,34,36; 151, pp.2,66). Ra-226 analysis was performed by ALS
Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Ref. 151, pp.2,105).
Table 5. Sample Description unci Analytical Results lor AOC 2
Sit m pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 9)
4, P-35; 43,
p.961,962
B9-
SS04-01-
050718
0-6"
Sandy
loam
1805320-8
5/7/18
Lead
(mg/kg)
6.3
0.21
43, p.6850;
90, pp.6,36;
220, pp.36,37
B9-
SS04-01-
050718
0-6"
Sandy
loam
1805320-8
5/7/18
Uranium
(mg/kg)
2.0
0.011
43, p.6850;
90, pp.6,36;
220, pp.36,37
BSA-9
0-6"
Sandy
loam
1805319
5/7/18
Radium-
226 (pCi/g)
1.94*
NA
43, p.6850;
90, p.10; 200,
p.2; 220, p.30
AOC Samples - Mesa I Mine 11 Waste Pile M4 and
Jurial Cell 9
M4-
XS63-
02-
050718
0-3"
Waste
rock
sand
1805322-8
5/7/18
Lead
(mg/kg)
20
0.2
89, pp.6,36;
220, p.49
M4-
SS81-01-
091818
0-6"
Silty
sand
1809412-16
9/18/18
Uranium
(mg/kg)
130
0.088
4, p.222; 151,
pp.5,66; 220,
p.556, 557
M4-
SS176-
01-
091818
0-6"
Silty
sand
1809413-11
9/18/18
Radium-
226 (pCi/g)
102 M3
NA
4, p.225; 151,
p.13,105; 220,
p.562
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, p. 116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC (Ref. 151, p. 105).
HRS Documentation Record
49
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Number by which this AOC is to be identified: 3
Name of AOC: Mesa I Mine 12 Waste Pile M5A, Waste Pile M5B, and Waste Pile M5C
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 4
AOC 3 comprises three waste piles: Mesa I Mine 12 Waste Pile M5A, Waste Pile M5B, and Waste Pile M5C. All
three waste piles are aggregated into a single AOC because of their proximity, similar waste type, same AOC
type, impacts on the same targets, and similar past operational history (Ref. 5, pp.33,35). Waste Pile M5B is the
largest of the three waste piles with an approximate depth of 7.5 feet. This waste pile is highly erodible and likely
erodes downgradient to the Cove Wash Middle 3E drainage (Ref. 5, p.33). Waste Pile M5A is smaller and
contains more vegetation. Waste Pile M5A is approximately 2 feet deep (Ref. 5, p.33). Waste Piles M5A and
M5B sit on a slope greater than 30 degrees. Waste Pile M5C is an extension of Waste Piles M5A and M5B. Waste
Pile M5C is below a cliff in the southwestern portion of the mine and accessible from the Cove Wash Middle 3E
drainage. Offsite migration at Waste Pile M5C was documented as the Cove Wash Middle 3E drainage cuts
directly through the mine feature. Drainages and erosional features are present on all three waste piles (Ref. 5,
p.33). The waste generated is a result of mine operations in ore bodies within the Salt Wash Member of the Lower
Morrison Formation (Ref. 5, pp.24,25). Surficial contamination documented in the AOC sample results below
shows that the waste piles do not have a continuous cover of 2 feet or greater. The workings for Mesa I Mine 12
are connected to Mesa I Mine 13 (Ref. 5, pp.28,29).
All waste samples are surface samples collected from the waste piles but are generally referred to in the RSE
report as soil samples. Observed contamination is established by analytical significance above background levels.
For surface waste samples analyzed for metals, observed contamination is established when the metal
concentration is three times the highest background concentration. Background levels are determined based on the
highest analyte-specific background concentration from the AOC-specific background study area (Refs: 5, p.37;
43, p.960). For Ra-226, observed contamination is established when the Ra-226 concentration is two standard
deviations above the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All
Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1,
pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174).
BSA-9 was selected as the most appropriate background location for AOC 3 because it is within the same
geologic unit (Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC in the
same geology and soil type (Ref. 43, pp. 45,46,940,943). The highest background concentration for each metals
analyte from the 30 samples comprising BSA-9 was used as the background level for AOC 3 (Ref. 43, p. 963).
The Ra-226 mean plus two standard deviations from the 30 samples comprising BSA-9 was used as the
background level for AOC 3 (Refs. 43, pp. 966; 200, p.2). The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Ref. 91, pp.2,115,117). Ra-226
analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy
(Ref. 91, pp.2,228,230).
Table 6. Sample Description :tiul Analytical Results lor AOC 3
S;t m pic
II)
Sain pie
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a nee
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 9)
5, p.37; 43.
p.960
B9-
SS04-
01-
0-6"
Sandy
loam
1805320-8
5/7/18
Uranium
(mg/kg)
2.0
0.011
43,
pp.6850,
6851; 90,
HRS Documentation Record
50
Lukachukai Mountains Mining District
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Table 6. Sample Description :tiul Analytical Results lor AOC 3
S;t m pic
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Su list a nee
Substance
Cone.
Limit2
050718
pp.t>,3t>;
220, p.36,
37
BSA-9
0-6"
Sandy
loam
1805319
5/7/18
Radium-
226 (pCi/g)
1.94*
NA
43,
pp.6850,
6851; 200,
pi; 90,
p.10; 220,
p.30
AOC Sample - Mesa I Mine 12 Waste Pile M5A
M5-
0-6"
Silty
1810124-33
9/30/18
Uranium
79
0.084
5, P-241;
SS149-
sand
(mg/kg)
91, pp.7,
01-
115; 220,
093018
pp.824, 825
M5-
0-6"
Silty
1810125-33
9/30/18
Radium-
36
NA
5, P-241;
SS149-
sand
226 (pCi/g)
91, pp. 11,
01-
228; 220,
093018
pp.834, 835
AOC Sample - Mesa I Mine 12 Waste Pile M5B and Waste Pile IV
[5C
M5-
0-6"
Silty
1810124-34
9/30/18
Uranium
270
0.098
5, p.242;
SS185-
sand
(mg/kg)
91, pp.7,
01-
117; 220,
093018
p.824, 825
M5-
0-6"
Silty
1810125-34
9/30/18
Radium-
152
NA
5, p.242;
SS185-
sand
226 (pCi/g)
91, pp. 11,
01-
230; 220,
093018
pp.834, 835
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 4
Name of AOC: Mesa I Mine 13 Waste Pile M6
AOC Type: Pile
HRS Documentation Record
51
Lukachukai Mountains Mining District
NNN000920223
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Location and description of AOC (with reference to a map of the area): Figure 4
AOC 4 comprises one waste pile: Mesa I Mine 13 Waste Pile M6. AOC 4 has high potential for erosion and
offsite migration because of its location directly within the Cove Wash Middle 3F drainage, which bisects the
Mesa I Mine 13 area (Ref. 6, pp.32,33). The waste generated is a result of mine operations in ore bodies within
the Salt Wash Member of the Lower Morrison Formation (Ref. 6, pp.23,24). Surficial contamination documented
in the AOC sample results below shows that the waste pile does not have a continuous cover of 2 feet or greater.
The workings for Mesa I Mine 13 and Mesa I Mine 12 are interconnected beneath the mesa (Ref. 6, p. 27, 28).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs: 6, p.35; 43, p.960). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
BSA-9 was selected as the most appropriate background location for AOC 4 because it is within the same
geologic unit (Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC in the
same geology and soil type (Ref. 43, pp. 45,46,940,943). The highest background concentration for each metals
analyte from the 30 samples comprising BSA-9 was used as the background level for AOC 4 (Ref. 43, p. 963).
The Ra-226 mean plus two standard deviations from the 30 samples comprising BSA-9 was used as the
background level for AOC 4 (Refs. 43, pp.966; 200, p.2). The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Refs. 120, pp.2,88; 154, pp.2,51).
Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Ref. 154, pp.2,166).
Table 7. Sample Description and Analytical Results lor AOC 4
Sample 11)
Sample
Depth
Soil
Type1
Laboratory
Sample 1D
Dale
1 la/arilous
Su list a nee
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (E
5SA9)
6, p.35; 43,
pp.960,962
B9-SS12-
01-050718
0-6"
Sandy
loam
1805320-
16
5/7/18
Arsenic
(mg/kg)
2.4
0.21
43, pp.6850,
6851; 90,
pp.6,52;
220, pp.36,
37
B9-SS04-
01-050718
0-6"
Sandy
loam
1805320-8
5/7/18
Uranium
(mg/kg)
2.0
0.011
43, pp.6850,
6851; 90,
pp.6,36;
220, pp.36,
37
BSA-9
0-6"
Sandy
loam
1805319
5/7/18
Radium-
226
(pCi/g)
1.94*
NA
43, pp.6850,
6851; 90,
p.10; 200,
HRS Documentation Record
52
Lukachukai Mountains Mining District
NNN000920223
-------
p.l; 220,
pp.30, 31
AOC Sample - Mesa I Mine 13 Waste Pile M6
M6-XS224-
01-091118
0-3"
Waste
rock
sand
1809473-
34
9/11/18
Arsenic
(mg/kg)
17
0.2
120,
pp.6,88;
220,
pp.611,613
M6-SS252-
01-091618
0-6"
Silty
sand
1809479-5
9/16/18
Uranium
(mg/kg)
36
0.0092
6, P-257;
154,
pp.7,51;
220, p.868
M6-SS252-
01-091618
0-6"
Silty
sand
1809480-5
9/16/18
Radium-
226
(pCi/g)
23
NA
6, P-257;
154,
pp.12,166;
220,
pp.676,677
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 5
Name of AOC: Mesa I Mine 14 Waste Pile M7A, Waste Pile M7B, and Waste Pile M7C
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 4
AOC 5 comprises three waste piles: Mesa I Mine 14 Waste Pile M7A, Waste Pile M7B, and Waste Pile M7C. All
three waste piles are aggregated into a single AOC because of their proximity, similar waste type, same AOC
type, impacts on the same targets, and similar past operational history (Ref. 7, p.32). Both Waste Pile M7A and
Waste Pile M7B are on a slope greater than 30 degrees and 3 to 5 feet deep (Ref. 7, pp.32,34). Both waste piles
are highly erodible, and offsite migration has been documented down the cliff below these piles. A waste pile
discovered down the cliff below Waste Piles M7A and M7B was designated as Waste Pile M7C (Ref. 7, pp.
32,33). Waste Pile M7C is an extension of Waste Piles M7A and M7B and sits directly within the Cove Wash
Middle 3E drainage (Ref. 7, p.33). The waste in AOC 5 was generated as a result of mine operations in ore bodies
within the Salt Wash Member of the Lower Morrison Formation (Ref. 7, pp.24,25). Surficial contamination
documented in the AOC sample results below shows that the waste piles do not have a continuous cover of 2 feet
or greater. The workings for Mesa I Mine 14 extend northeast of the mine (Ref. 7, p.28,29).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
HRS Documentation Record
53
Lukachukai Mountains Mining District
NNN000920223
-------
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs: 7, p.36; 43, p.960). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
BSA-9 was selected as the most appropriate background location for AOC 5 because it is within the same
geologic unit (Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC in the
same geology and soil type (Ref. 43, pp. 45,46,940,943). The highest background concentration for each metals
analyte from the 30 samples comprising BSA-9 was used as the background level for AOC 5 (Ref. 43, p. 963).
The Ra-226 mean plus two standard deviations from the 30 samples comprising BSA-9 was used as the
background level for AOC 5 (Refs. 43, pp. 966; 200, p. 2). The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Refs. 96, pp.2,28,36; 156, pp.2,50).
Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Ref. 96, pp.2,69,77).
Table S. Sample Description unci Analytical Results lor AOC 5
Sit m pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 9)
7, P-36; 43,
pp.960, 961,
962
B9-
SS04-01-
050718
0-6"
Sand
1805320-8
5/7/18
Lead
(mg/kg)
6.3
0.21
43, pp.6850,
6821; 90,
pp.6, 36;
220, pp.36,
37
B9-
SS04-01-
050718
0-6"
Sand
1805320-8
5/7/18
Uranium
(mg/kg)
2.0
0.011
43, pp.6850,
6851; 90,
pp.6,36;
220, pp.36,
37
BSA-9
0-6"
Sandy
loam
1805319
5/7/18
Radium-
226 (pCi/g)
1.94*
NA
43, pp.6850,
6851; 200,
pi; 90,
p.10; 220,
p.30
AOC Samples (Mesa I Mine 14 Waste Pile
M7A)
M7-
SS161-
01-
091618
0-6"
Waste
Rock
1809453-7
9/16/18
Lead
(mg/kg)
20
0.2
7, p.223;
156, p. 50;
220, pp.879,
880
M7-
XS162A-
01-
081518
0-3"
Waste
rock
sand
1808356-5
8/15/18
Uranium
(mg/kg)
270
0.097
96, pp.5,28;
220, pp.427,
428
HRS Documentation Record
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Lukachukai Mountains Mining District
NNN000920223
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Table S. Sample Description unci Analytical Results lor AOC 5
Sit m pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
\17-
XS162A-
01-
081518
n-3"
Was l^-
rock
sand
1XIIX3NI-5
X 15 IS
Radium-
226 (pCi/g)
195 \13
\A
pp^^.
220, pp.432,
433
AOC Sample (Mesa I Mine :
4 Waste Pile M7B and Waste Pile M7C)
M7-
XS235A-
01-
081418
0-3"
Waste
rock
sand
1808356-9
8/14/18
Uranium
(mg/kg)
140
0.099
96, pp.5,36;
220, pp.427,
428
M7-
XS235A-
01-
081418
0-3"
Waste
rock
sand
1808360-9
8/14/18
Radium-
226 (pCi/g)
108 M3
NA
96, pp.5,77;
220, pp.432,
433
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC (Ref. 96, p. 77).
Number by which this AOC is to be identified: 6
Name of AOC: Mesa I Mine 15 Burial Cell 6a, Burial Cell 6b, Burial Cell 7, Waste Pile M8A, and Waste Pile
M8B
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 4
AOC 6 comprises five waste piles: Mesa I Mine 15 Waste Pile M8A, Waste Pile M8B, Burial Cell 6a, Burial Cell
6b, and Burial Cell 7 (Ref. 8, pp.33,34). All five piles are aggregated into a single AOC because of their
proximity, similar waste type, same AOC type, same ore body, impacts on the same targets, and similar past
operational history (Ref. 8, pp.33,34). Both Waste Pile M8A and Waste Pile M8B are approximately 2 feet deep
on a slope greater than 30 degrees in places. Waste Piles M8A and M8B are highly erodible, and offsite migration
likely flows downgradient to the Cove Wash Middle 3F drainage (Ref. 8, p.33). Burial Cells 6a and 6b are
adjacent to each other and located southeast of Waste Pile M8B (Ref. 8, p.34). Burial Cell 7 lies within and is
comingled with Waste Pile M8B (Ref. 8, p.34). The waste generated in AOC 6 is the result of mine operations in
ore bodies within the Salt Wash Member of the Lower Morrison Formation (Ref. 8, pp.24, 25). Surficial
contamination documented in the AOC sample results below shows that the waste piles do not have a continuous
cover of 2 feet or greater. The workings for Mesa I Mine 15 extend into Mesa I Mine 11 (Ref. 8, pp. 28, 29).
HRS Documentation Record
55
Lukachukai Mountains Mining District
NNN000920223
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All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE
report as soil samples. Observed contamination is established by analytical significance above background levels.
For surface waste samples analyzed for metals, observed contamination is established when the metal
concentration is three times the highest background concentration. Background levels are determined based on
the highest analyte-specific background concentration from the AOC-specific background study area (Refs: 8,
p.36; 43, p.960). For Ra-226, observed contamination is established when the Ra-226 concentration is two
standard deviations above the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp.
1-2). All Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g.
(Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174).
BSA-9 was selected as the most appropriate background location for AOC 6 because it is within the same
geologic unit (Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC (Ref. 43,
pp. 45,46,940,943). The highest background concentration for each metals analyte from the 30 samples
comprising BSA-9 was used as the background level for AOC 6 (Ref. 43, p. 963). The Ra-226 mean plus two
standard deviations from the 30 samples comprising BSA-9 was used as the background level for AOC 6 (Refs.
43, pp. 966; 200, p. 2). The metals analysis was performed by ALS Environmental Laboratories using USEPA
method SW-846 6020A ICP-MS (Refs. 97, pp.2,113,127; 154, pp.2,117; 157, pp.2,36). Ra-226 analysis was
performed by ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Refs. 97,
pp.2,208; 157, pp.2,76).
Table (). Sample Description
and Analytical Results lor AOC ft
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
Background Sample (BSA 9)
8, P-36; 43,
p.962
B9-
0-6"
Sandy
1805320-8
5/7/18
Uranium
2.0
0.011
43, pp.6850,
SS04-01-
loam
(mg/kg)
6851; 90,
050718
pp.6,36;
220, pp.36,
37
BSA-9
0-6"
Sandy
loam
1805319
5/7/18
Radium-
226 (pCi/g)
1.94*
NA
43, pp.6850,
6851; 90,
p.10; 200,
p.l; 220,
p.30
AOC Sample - Mesa I Mine 15 Waste Pile M8A
M8-
0-6"
Silty
1810077-48
9/27/18
Uranium
46
0.0098
8, p.230; 97,
SS120-
sand
(mg/kg)
pp.6,127;
01-
220, pp.781,
092718
783
M8-
0-6"
Silty
1810076-39
9/27/18
Radium-
12.2
NA
8, p.228; 97,
SS106-
sand
226 (pCi/g)
pp.15,208;
01-
220, pp.771,
092718
773
HRS Documentation Record
56
Lukachukai Mountains Mining District
NNN000920223
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Table 9. Sample Description unci Analytical Results lor AOC 6
S;t in pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Report in»
Limit2
Reference
AOC Sample - Mesa I Mine 15 Waste Pile M8B, Burial Cell 6a, Burial Cell 6b, and Burial Cell 7
M8-
XS83-
01-
081418
0-3"
Waste
rock
sand
1808476-12
8/14/18
Uranium
(mg/kg)
180
0.095
157,
pp.5,36;
220, pp.442,
443
M8-
XS83-
01-
081418
0-3"
Waste
rock
sand
1808475-12
8/14/18
Radium-
226 (pCi/g)
139 M3
NA
157,
pp.9,76;
220, pp.437,
438
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC (Ref. 157, p. 76).
Number by which this AOC is to be identified: 7
Name of AOC: Mesa I Camp Waste Pile T17A, Waste Pile T17B, and Burial Cell 310AB
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 4
AOC 7 comprises three waste piles: Mesa I Camp Waste Pile 17A, Waste Pile T17B, and Burial Cell 310AB
(Ref. 41, pp.31,32). All three piles are aggregated into a single AOC because of their proximity, similar waste
characteristics, same AOC type, same ore body, impacts on the same targets, and similar past operational history
(Ref. 41, pp.31,32). Mesa I Camp was a former mining field camp on Mesa I where a consolidated reclamation
burial cell is located (Ref. 41, pp.26,31). Waste Pile T17A is located east and upgradient of Burial Cell 310AB,
and Waste Pile T17B is located west and downgradient of Burial Cell 310AB (Ref. 41, pp.22,32). A small
drainage was identified on Waste Pile T17B (Ref. 41, p.31). Burial Cell 310AB consists of waste from Mesa I
Mine 13 and Mesa I Mine 15 (Ref. 41, p.30). Subsurface soil sampling results estimated a waste depth of 3 feet at
Waste Pile T17A and Waste Pile T17B and adepth of 4.5 feet at Burial Cell 310AB (Ref. 41, p.132). The waste
generated is a result of mine operations in ore bodies within the Salt Wash Member of the Lower Morrison
Formation (Ref. 41, pp.23,24). Surficial contamination documented in the AOC sample results below shows that
the waste piles do not have a continuous cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
HRS Documentation Record
57
Lukachukai Mountains Mining District
NNN000920223
-------
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs: 41, p.34; Ref. 43,
p. 1276). For Ra-226, observed contamination is established when the Ra-226 concentration is two standard
deviations above the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All
Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1,
pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174).
BSA-12 was selected as the most appropriate background location for AOC 7 because it is within the same
geologic unit (Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC with the
same geology and soil type (Ref. 43, pp. 45,46,1256,1259). The highest background concentration for each metals
analyte from the 30 samples comprising BSA-12 was used as the background level for AOC 7 (Ref. 43, p. 1279).
The Ra-226 mean plus two standard deviations from the 30 samples comprising BSA-12 was used as the
background level for AOC 7 (Refs. 43, pp. 1282; 200, p. 2). The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Refs. 144, pp.2,71; 148, pp.2,37).
Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Ref. 144, pp.2,124).
Table 10. Sample Description itiul Analytical Results
lor AOC 7
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
Background Sample (BSA 12)
41, P-34; 43,
pp.1277,
1278
B12-
0-6"
Sand
1805324-17
5/9/18
Lead
18
0.22
43, pp.6875,
SS13-01-
(mg/kg)
6876; 145,
050918
pp.6,54;
220, pp.60,
61
B12-
0-6"
Sand
1805324-17
5/9/18
Uranium
3.3
0.011
43, pp.6876,
SS13-01-
(mg/kg)
6877; 145,
050918
pp.6,54;
220, pp.60,
61
BSA-12
0-6"
Sand
1805323
5/9/18
Radium-
226 (pCi/g)
2.41*
NA
43, pp.6876,
6877;200,
p.2; 145,
p. 10; 220,
p.54
AOC Samples - Mesa I Camp Waste Pile T17A, Waste Pile T17B, and Burial Cell 310AB
T17-
0-3"
Waste
1805039-9
4/26/18
Lead
120
0.22
148, pp.5,
XS144-
rock
(mg/kg)
37; 220,
01-
sand
pp.884, 885
042618
T17-
0-6"
Silty
1810001-19
9/25/18
Uranium
410
0.99
41, p.388;
SS143-
01-
sand
(mg/kg)
144, pp.6,
71; 220,
092518
pp.686, 687
HRS Documentation Record
58
Lukachukai Mountains Mining District
NNN000920223
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Tiihle 10. Siimple Description itiul Aiiiilvticiil Results lor AOC 7
Siimple
II)
Siimple
Depth
Soil
Type1
l.iihoriilorv
Siimple 1D
Diite
1 lii/iirilous
Siibsliince
1 lii/iirilous
Su list it nee
Cone.
Reporting
Limit2
Re Terence
T17-
SS143-
01-
092518
i.i-O"
Sill)
sand
iXlijijiP-lw
y :5 is
Radium-
226 (pCi/g)
Ibb _\13
\A
41, p.388,
144, p.13,
124; 220,
pp.692, 693
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC (Ref. 144, p. 124).
Number by which this AOC is to be identified: 8
Name of AOC: Mesa I 1/4 Mine Waste Pile M9
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 4
AOC 8 comprises one waste pile: Mesa I 1/4 Mine Waste Pile M9. Waste Pile M9 is approximately 1 foot deep
(Ref. 9, p.30). Waste Pile M9 extends down into the Cove Wash Middle 3E drainage and has potential for erosion
because of the steep topography (Ref. 9, pp.30,31,130). The waste generated is a result of mine operations in ore
bodies within the Salt Wash Member of the Lower Morrison Formation (Ref. 41, pp.22,23). Surficial
contamination documented in the AOC sample results below shows that the waste pile does not have a continuous
cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs: 9, p.33; 43, p. 1382). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
BSA-13 was selected as the most appropriate background location for AOC 8 because it is within the same
geologic unit (lower Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC
(Ref. 43, pp.45,46,1362,1365). The highest background concentration for each metals analyte from the 30
samples comprising BSA-13 was used as the background level for AOC 8 (Ref. 43, p. 1385). The Ra-226 mean
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Lukachukai Mountains Mining District
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plus two standard deviations from the 30 samples comprising BSA-13 was used as the background level for AOC
8 (Refs. 43, pp. 1388; 200, p. 2). The metals analysis was performed by ALS Environmental Laboratories using
USEPA method SW-846 6020A ICP-MS (Ref. 99, pp.2,35). Ra-226 analysis was performed by ALS
Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Ref. 99, pp.2,78).
Table 11. Sample Description iincl Analytical Results lor AOC S
S;t in pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a nee
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 13)
9, P-33;
43, p.1384
B13-
SS23-01-
071518
0-6"
Silty
sand
1807350-26
7/15/18
Uranium
(mg/kg)
0.85
0.011
43,
pp.6884,
6885; 88,
pp.6,71;
220,
pp.361,
362
BSA-13
0-6"
Silty
sand
1807351
7/15/18
Radium-
226 (pCi/g)
1.54*
NA
43,
pp.6884,
6885; 200,
p.2; 88,
p.10; 220,
p.369
AOC Sample - Mesa 11/4 Mine Waste Pile
M9
M9-
XS28A-
01-
081718
0-3"
Waste
rock
sand
1808483-9
8/17/18
Uranium
(mg/kg)
150
0.093
99,
pp.5,35;
220,
pp.447,
448
M9-
XS28A-
01-
081718
0-3"
Waste
rock
sand
1808484-9
8/17/18
Radium-
226 (pCi/g)
110 J-
NA
48, pp.7,8;
99,
pp.8,78;
220,
pp.452,
453
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
J- The analyte was detected at the reported concentration; the quantitation is an estimate and may be biased
low. As a source sample, the concentration of this qualified data is reported without adjustment (Ref. 48,
P-7, 8).
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Number by which this AOC is to be identified: 9
Name of AOC: Mesa I 1/2 Mine Waste Pile Ml OA and Waste Pile Ml OB
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 4
AOC 9 comprises two waste piles: Mesa I 1/2 Mine Waste Pile M10A and Waste Pile M10B. Both waste piles are
aggregated into a single AOC because of their proximity, similar waste type, same AOC type, similar past
operational history, impacts on the same targets, and because Waste Pile Ml OA is the result of waste falling from
Waste Pile Ml OB over a cliff and accumulating below. Waste Pile Ml OA extends into the Cove Wash Middle 3E
drainage (Ref. 10, pp.29,30). Waste Pile M10B is north and upgradient of Waste Pile M10A (Ref. 10, p.31).
Additional drainages run through the waste piles into the Cove Wash Middle 3E drainage (Ref. 10, p.31).
Furthermore, the steep topography also presents a high potential for offsite migration into the Cove Wash Middle
3E drainage (Ref. 41, p.129). The waste generated is a result of mine operations in ore bodies within the Salt
Wash Member of the Lower Morrison Formation (Ref. 10, p.22). Surficial contamination documented in the AOC
sample results below shows that the waste piles do not have a continuous cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs: 10, p.33; 43, p. 1589). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
BSA-15 was selected as the most appropriate background location for AOC 9 because it is within the same
geologic unit (undifferentiated Summerville and Entrada Formations), it hosts soil of the same type, and it is the
closest BSA to the AOC (Ref. 43, pp. 45,46,1567,1570). The highest background concentration for each metals
analyte from the 30 samples comprising BSA-15 was used as the background level for AOC 9 (Ref. 43, p. 1590).
The Ra-226 mean plus two standard deviations from the 30 samples comprising BSA-15 was used as the
background level for AOC 9 (Refs. 43, pp. 1593; 200, p. 2). The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Refs. 86, pp.2,29; 101, pp.2,92). Ra-
226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Ref. 152, pp.2,20).
Table 12. Sample Description itiul Analytical Results lor AOC ()
Sample
II)
Saniplc
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Samp
e (BSA
15)
10, p.33; 43,
p.1589
B15-
SS11-
01-
0-6"
Sand
1807264-16
7/11/18
Uranium
(mg/kg)
1.7
0.01
43, p.6904;
100, pp.6,52;
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Table 12. Sample Description and Analytical Results lor AOC ()
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/ardous
Substance
1 la/ardous
Substance
Cone.
Reporting
Limit2
Reference
U71118
22u, pp.2y5,
296
BSA-15
0-6"
Sand
1807265
7/11/18
Radium-
226 (pCi/g)
1.33*
NA
43, pp.6900,
6901; 200,
p.2; 100,
p.10; 220,
p.303
AOC Samples - Mesa 11/2
Mine Waste Pile M10A and Waste Pi
e M10B
M10-
SS10-
01-
092818
0-6"
Silty
sand
1810080-23
9/28/18
Uranium
(mg/kg)
99
0.01
10, p.178;
101, pp.7,92;
220, pp.799,
800
M10-
XS43-
01-
082118
0-3"
Waste
rock
sand
1808495-3
8/21/18
Radium-
226 (pCi/g)
52.1
NA
152, pp.7,20;
220, pp.471,
472
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Areas of Observed Contamination 10 to 17 - Mesa II
Eight AOCs are scored as a result of mining activities at Mesa II.
Table 13. Mesa II AOC s
AOC
No.
AOC
Type
Mine/Claim Names
RSI! Waste Pile Names
10
Pile
Mesa I 1/2, West Mine
Waste Pile M12
11
Pile
Mesa I 3/4 Incline
Waste Pile M25; Burial Cells 3 la and 3 lb
12
Pile
Mesa II, Mine No. 1, P-150; Mesa II,
Mine No. 1 & 2, P-21; Mesa I 3/4, Mine
No. 2, P150
Waste Piles M27 and M28; Burial Cell 39
13
Pile
Mesa II, Mine 4
Waste Piles M29A and M29B; Burial Cell 43
14
Pile
Mesa II Pit
Waste Pile M24; Burial Cell 44
15
Pile
Mesa II 1/4 Mine
CO-07 NNWP01 and CO-07 NNWP02
16
Pile
Henry Philips Mine
Waste Pile Mil
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Table 13. Mesa II AOC s
AOC
No.
AOC
Typo
Mine/Claim Names
RSE Waste Pile Names
17
Pile
Billy Topaha Mine
CO-03 CAWP01
All mine claims in the Mesa II geographic area except Henry Philips Mine and Mesa II % Mine were developed
and operated in the 1950s and 1960s by F.A. Sitton, the Navajo Uranium Mining Company, Kerr-McGee (a
predecessor of Tronox), and VCA (Refs. 11, p.24; 12, p.24; 24, p.25; 25, p.26; 27, p.25; 28, p.25; 29, p.25). The
Henry Philips Mine and Mesa II 1/4 Mine were developed in the 1960s by Cyprus Amax, a successor of the
Climax Uranium Corporation and VCA (Refs. 82, p.2; 83, p.2). Operations at all mines included underground
mining that tapped paleochannels in the Salt Wash Member of the Lower Morrison Formation that are rich in
uranium and vanadium (Refs. 11, pp.21,24; 12, pp.21; 24, pp.22,25; 25, pp.23,26; 27, pp.22,25; 28, pp.22,25; 29,
pp.22,25; 82, pp. 1,5; 83, pp. 1,5). Underground mine workings exist throughout the Mesa II area. Waste piles
consist of overburden or lower grade protore discarded near or downslope of portals (Refs. 11, pp.27,28; 12,
pp.24,28; 24, pp.30,31; 25, pp.27,28,32,33; 27, pp.26,27,31,32; 28, pp.26,29,30; 29, pp.29,30; 82, pp.2,4,5; 83,
PP.2,4).
Number by which this AOC is to be identified: 10
Name of AOC: Mesa I 1/2, West Mine Waste Pile M12
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 5 and Figure 6
AOC 10 comprises one waste pile: Mesa I 1/2, West Mine Waste Pile M12. The Cove Wash Middle 3D drainage
cuts through Waste Pile M12. At the bottom of the drainage is a large waterfall with a vertical drop estimated over
75 feet (Ref. 12, pp.24,25). The onsite drainage eventually connects to the Cove Wash Middle 3A drainage (Ref.
12, pp. 18,19). Waste Pile M12 is highly erodible, and offsite waste migration has been documented. Surficial
contamination documented in the AOC sample results below shows that the waste pile does not have a continuous
cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the background
samples from the AOC-specific background study area (Ref. 12, p.31; Ref. 43, p. 1483). For Ra-226, observed
contamination is established when the Ra-226 concentration is two standard deviations above the mean site-
specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for this AOC also
exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp. 2,3; 221, p.25;
222, pp.171-174).
BSA-14 was selected as the most appropriate background location for AOC 10 because it is within the same
geologic unit (lower Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC
(Ref. 43, pp. 45,46,1463,1466). The highest background concentration for each metals analyte from the 30
samples comprising BSA-14 was used as the background level for AOC 10 (Ref. 43, p. 1486). The Ra-226 mean
plus two standard deviations from the 30 samples comprising BSA-14 was used as the background level for AOC
10 (Refs. 43, pp. 1489; 200, p. 2). The metals analysis was performed by ALS Environmental Laboratories using
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USEPA method SW-846 6020A ICP-MS (Ref. 101, pp.2,106). Ra-226 analysis was performed by ALS
Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Ref. 86, pp.2,73).
Table 14. Sample Description itiul Analytical Results lor AOC 10
Nil m pic
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 lazarilous
Su list a nee
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Samp
es (BSA ]
4)
12, p.31;
43, p.1485
B14-
SS15-
01-
071518
0-6"
Silty
sand
1807353-18
7/15/18
Uranium
(mg/kg)
0.55
0.011
43, p.6896;
102,
pp.6,54;
220,
pp.375, 376
BSA-14
0-6"
Silty
loam
1807354
7/15/18
Radium-
226 (pCi/g)
0.8*
NA
43, p.6892,
6893; 200,
p.2; 102,
p. 10; 220,
p.383
AOC Samples - Mesa 11/2 West Mine Waste Pile M12
M12-
SS33-
01-
092818
0-6"
Silty
sand
1810080-30
9/28/18
Uranium
(mg/kg)
6.7
0.0091
12, p.180;
101,
pp.7,106;
220,
pp.799, 800
M12-
XS27-
01-
071518
0-3"
Waste
rock
sand
1807370-6
7/15/18
Radium-
226 (pCi/g)
5.22
NA
86,
pp.9,73;
220,
pp.413, 414
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 11
Name of AOC: Mesa I 3/4 Incline Waste Pile M25, Burial Cell 31a, and Burial Cell 3 lb
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 5 and Figure 6
AOC 11 comprises three waste piles: Mesa I 3/4 Incline Waste Pile M25, Burial Cell 31a, and Burial Cell 3 lb.
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All three piles are aggregated into a single AOC because of their proximity, similar waste characteristics, same
AOC type, same ore body, impacts on the same targets, and similar past operational history. Waste Pile M25,
Burial Cell 3 la, and Burial Cell 3 lb are near one other in the southeastern portion of the mine and are the result of
the same mining operations. AOC 11 is approximately 3 feet deep (Ref. 25, pp.32,33). A drainage bisects the
mine area and Waste Pile M25 and connects to the Cove Wash Middle 3C drainage (Ref. 25, pp. 19,21). Waste
Pile M25 is erodible, and offsite waste migration has been documented to flow into the Cove Wash Middle 3C
drainage. Onsite waste was placed into Burial Cells 3 la and 3 lb (Ref. 25, p. 133). As a part of the reclamation
process, NAML placed 1.5 feet of cover material over both Burial Cell 31a and Burial Cell 3 lb in 2001. In
addition, a 230-foot diversion berm was constructed to divert water away from Burial Cell 31b (Ref. 25, p.30).
The waste is a result of mine operations in ore bodies in the Salt Wash Member of the Lower Morrison Formation
(Ref. 25, pp.23,24,26). Surficial contamination documented in the AOC sample results below shows that the
waste piles do not have a continuous cover of 2 feet or greater. The workings of Mesa I 3/4 Incline extend to
Mesa II, Mine No, 1 & 2, P-21 (Ref. 25, pp.27,28).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 25, p.35; 43, p.3035). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
BSA-30 was selected as the most appropriate background location for AOC 11 because it is within the same
geologic unit (lower Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC
(Ref. 43, pp. 45,46,3015,3018). The highest background concentration for each metals analyte from the 30
samples comprising BSA-30 was used as the background level for AOC 11 (Ref. 43, p.3038). The Ra-226 mean
plus two standard deviations from the 30 samples comprising BSA-30 was used as the background level for AOC
11 (Refs. 43, pp.3041; 200, p. 2). The metals analysis was performed by ALS Environmental Laboratories using
USEPA method SW-846 6020A ICP-MS (Ref. 101, pp.2,124). Ra-226 analysis was performed by ALS
Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Ref. 101, pp.2,227).
Table 15. Sample Description itiul Analytical Results lor AOC 11
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 30)
25, p.35; 43,
p.3035,3037
B30-
SS19-01-
071018
0-6"
Sand
1807262-22
7/10/18
Arsenic
(mg/kg)
2.1
0.2
43, p.7025;
126,
pp.6,64;
220, pp.279,
280
B30-
SS30-01-
071018
0-6"
Sand
1807262-34
7/10/18
Uranium
(mg/kg)
0.67
0.0091
43, p.7026;
126,
pp.6,88;
220, pp.279,
281
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Table 15. Sample Description itiul Analytical Results lor AOC 11
S;t in pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
BSA-30
i.i-O"
Sand,
sandy
loam,
silty
sand
1S(
7 in 18
Radium-
226 (pCi/g)
().S9:;:
\A
43, pp.7u^n,
7021; 200,
p.2; 126,
p. 10; 220,
p.287
AOC Sample - Mesa I 3/4 Incline Waste Pile M25, Burial Cell 31a, and Burial Cell 31b
M25-
SS50-01-
092818
0-6"
Silty
sand
1810080-39
9/28/18
Arsenic
(mg/kg)
7.4
0.19
25, p.185;
101,
pp.7,124;
220, pp.799,
801
M25-
SS50-01-
092818
0-6"
Silty
sand
1810080-39
9/28/18
Uranium
(mg/kg)
43
0.0097
25, p.185;
101,
pp.7,124;
220, pp.799,
801
M25-
SS50-01-
092818
0-6"
Silty
sand
1810079-39
9/28/18
Radium-
226 (pCi/g)
31.6
NA
25, p.185;
101,
p. 11,227;
220, pp.791,
793
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 12
Name of AOC: Mesa I 3/4, Mine No. 2, P-150, and Mesa II, Mine No. 1 & 2, P-21, Waste Pile M27 and Burial
Cell 39; Mesa II, Mine No. 1, P-150, Waste Pile M28
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 5 and Figure 6
AOC 12 comprises three waste piles: Mesa I 3/4, Mine No. 2, P-150, and Mesa II, Mine No. 1 & 2, P-21, Waste
Pile M27 and Burial Cell 39, and Mesa II, Mine No. 1, P-150, Waste Pile M28. These waste piles are aggregated
into a single AOC because of their proximity, same AOC type, impacts on the same targets, wastes eroding into
the same drainage, and wastes coming from the same ore body with interconnected underground workings (Refs.
27, pp.31,32; 28, pp.29,30). Waste Pile M27 is approximately 2 feet deep on a slope of approximately 35 degrees
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(Ref. 27, p.31). Burial Cell 39 is located adjacent to Waste Pile M27. Burial Cell 39 appears as a vegetated
landform with a channel incision and is being eroded by the Cove Wash Middle 3B drainage. The incised channel
reaches depths of more than 5 feet within Burial Cell 39 (Ref. 27, pp.31,32). Waste Pile M28 is approximately
5 feet deep on a slope greater than 45 degrees in areas. Waste Pile M28 is highly erodible, and offsite migration
has been documented (Ref. 28, pp.29,130). All waste piles are connected or extend into the nearby Cove Wash
Middle 3B drainage (Refs. 27, p.32; 28, p.30). The waste is a result of mine operations in ore bodies in the Salt
Wash Member of the Lower Morrison Formation (Refs. 27, pp.22,23; 28, pp.22,23). Surficial contamination
documented in the AOC sample results below shows that the waste piles do not have a continuous cover of 2 feet
or greater. The workings at Mesa II Mine No. 1 & 2, P-21, extend to Mesa II Mine No. 1, P-150, and Mesa I 3/4
Incline (Refs. 25, pp.27,28; 27, p.27). The workings at Mesa II Mine No. 1 & 2, P-21, also extent to Mesa II 1/2
Mine located west of the Mesa II area (Ref. 30, p.28).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study areas (Refs. 27, p.34; 43, p. 1066; 28,
p.32; 43, p.2515). For Ra-226, observed contamination is established when the Ra-226 concentration is two
standard deviations above the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp.
1-2). All Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g.
(Refs. 1, pp. 14,116; 200, pp. 2,3; 221, p.25; 222, pp. 171-174).
Because AOC 12 waste piles are spread across two geologies, two separate BSAs are used for different parts of
the AOC. For Mesa II Mine No. 1 & 2, P-21 Waste Pile M27 and Mesa II Mine No. 1 & 2, P-21 Burial Cell 39,
both BSA-10 and BSA-30 were deemed appropriate background locations because they are within the same
geologic unit (undifferentiated Summerville and Entrada Formations) and they host soil of the similar types
(Refs., 43, pp. 1046,3015; 27, p. 22). BSA-10 was selected as the BSA to establish background levels for the three
hazardous substances scored in these two waste piles because it has higher background concentrations than BSA-
30 (Ref. 43, pp. 1069,1072,3038,3041). The highest background concentration for each metals analyte from the 30
samples comprising BSA-10 was used as the background level for Waste Pile M27 and Burial Cell 39 (Ref. 43,
p. 1069). The Ra-226 mean plus two standard deviations from the 30 samples comprising BSA-10 was used as the
background level for Waste Pile M27 and Burial Cell 39 (Ref. 200, p.2).
For the Mesa II Mine No. 1, P-150 Waste Pile M28 waste pile, BSA-24 and BSA-29 were both found to be
appropriate BSAs. Mesa II Mine No. 1, P-150 Waste Pile M28 is partially within the Undifferentiated
Summerville Entrada Formation and to a lesser degree within the Lower Morrison (Ref. 28, p. 22). BSA-24 was
selected as the BSA to establish background levels for the three hazardous substances scored in these two waste
piles because it has higher background concentrations than BSA-29 (Ref. 43, pp.2518,2521,2935,2938). The
highest background concentration for each metals analyte from the 30 samples comprising BSA-24 was used as
the background level for Waste Pile M28 (Ref. 43, p.2518). The Ra-226 mean plus two standard deviations from
the 30 samples comprising BSA-24 was used as the background level for Waste Pile M28 (Ref. 200, p.2). The
metals analysis was performed by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-
MS (Refs. 129, pp.2,57; 130, pp.2,34; 129, pp.2,107). Ra-226 analysis was performed by ALS Environmental
Laboratories using USEPA method 901.1 gamma spectroscopy (Refs. 129, pp.2,149; 129, pp.2,199).
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Table 16. Sample Description itiul Analytical Results
lor AOC 12
Sample
Sample
Soil
Laboratory
Date
1 la/ardous
1 la/ardous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
Background Samp
e (BSA 10)
27, p.34; 43,
pp.1066,
1068
B10-
0-6"
Sandy
1805318-32
5/8/18
Arsenic
19
0.21
43, pp.6858,
SS27-
loam
(mg/kg)
6859; 131,
01-
pp.6,83;220,
050818
pp.24, 26
B10-
0-6"
Sandy
1805318-19
5/8/18
Uranium
6.3
0.011
43, pp.6858,
SS15-
loam
(mg/kg)
6859; 131,
01-
pp.6,57;
050818
220, pp.24,
25
BSA-10
0-6"
Sandy
loam
1805317
5/8/18
Radium-
226 (pCi/g)
6.04*
NA
43, pp.6858,
6859; 200,
p.l; 131,
p. 10; 220,
p.18
AOC Sample - Mesa II Mine No. 1 & 2, P-21 Waste Pile M27
M27-
0-6"
Silty
1810024-7
9/26/18
Uranium
26
0.0094
27, p.216;
SS51-
sand
(mg/kg)
129,
01-
092618
pp.7,57;
220, pp.710,
711
M27-
0-6"
Silty
1810025-7
9/26/18
Radium-
51.8
NA
27, p.216;
SS51-
01-
sand
226 (pCi/g)
129, pp.
15,149; 220,
092618
pp.718,719
AOC Sample - Mesa II Mine No. 1 & 2, P-21 Burial Cell 39
M27-
0-3"
Waste
1810072-6
9/26/18
Arsenic
58
0.19
130,
XSG28-
01-
rock
sand
(mg/kg)
pp.6,34;
220, pp.755,
092618
756
M27-
0-3"
Waste
1810072-6
9/26/18
Uranium
25
0.0097
130, pp.6,
XSG28-
rock
(mg/kg)
34; 220,
01-
sand
pp.755, 756
092618
Background Samp
e (BSA 24)
28, p.32; 43,
pp.2515,
2517
B24-
0-6"
Silty
1807365-29
7/16/18
Arsenic
3.5
0.22
43, p.6982;
SS26-
01-
sand
(mg/kg)
117, pp.6,
77; 220,
071618
pp.389, 390
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Table 16. Sample Description itiul Analytical Results
lor AOC 12
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Re Terence
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
b:4-
i.i-O"
Sill)
lX(i73ro-g
7 16 18
L ranium
LV
null
43, p
SS06-
sand
(mg/kg)
117, pp.6,
01-
37; 220,
071618
pp.389, 390
BSA-24
0-6"
Silty
sand
1807366
7/16/18
Radium-
226 (pCi/g)
2.06*
NA
43, pp.6977,
6978; 200,
p.2; 117,
p. 10; 220,
p.395
AOC Sample - Mesa II Mine No. 1, P-150 Waste Pile M28
M28-
0-6"
Silty
1810024-41
9/26/18
Arsenic
12
0.18
28, p.200;
SS30-
sand
(mg/kg)
129, pp.7,
01-
107; 220,
092618
pp.710, 712
M28-
0-6"
Silty
1810024-41
9/26/18
Uranium
230
0.092
28, p.200;
SS30-
sand
(mg/kg)
129, pp.7,
01-
107; 220,
092618
pp.710, 712
M28-
0-6"
Silty
1810025-32
9/26/18
Radium-
127 M3
NA
28, p.200;
SS30-
sand
226 (pCi/g)
129, pp.
01-
15,199; 220,
092618
pp.718, 720
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC (Ref. 129, p. 199).
Number by which this AOC is to be identified: 13
Name of AOC: Mesa II Mine 4 Waste Pile M29A, Waste Pile M29B, and Burial Cell 43
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 5 and Figure 6
AOC 13 comprises three waste piles: Mesa II Mine 4 Waste Pile M29A, Waste Pile M29B, and Burial Cell 43.
These waste piles are aggregated into a single AOC because of their proximity, same AOC type, impacts on the
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same targets, wastes eroding into the same drainage, and wastes coming from the same ore body with
interconnected underground workings. Waste Piles M29A and M29B are 3 feet deep on average with slopes
greater than 45 degrees. Burial Cell 43 is located against a highwall at the mine (Ref. 29, pp.29,30). Waste Pile
M29A is located at the base of a sandstone cliff downgradient of Burial Cell 43. The material at Waste Pile M29A
appears to be relatively confined. Waste Pile M29B is located below Burial Cell 43 on a steeper slope where
potential for erosion is likely (Ref. 29, p. 129). The waste generated is a result of mine operations in ore bodies in
the Salt Wash Member of the Lower Morrison Formation. Minor drainages run through the waste piles and
connect to the Cove Wash Middle 3A drainage located downgradient of the mine (Ref. 29, pp.30,135). Surficial
contamination documented in the AOC sample results below shows that the waste piles do not have a continuous
cover of 2 feet or greater (Ref. 223, p. 20).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Ref. 29, p.32; 43, p.2515). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
BSA-24 was selected as the most appropriate background location for AOC 13 because it is within the same
geologic unit (undifferentiated Summerville and Entrada Formations), it hosts soil of the same type, and it is the
closest BSA to the AOC (Ref. 29, p.31). The highest background concentration for each metals analyte from the
30 samples comprising BSA-24 was used as the background level for AOC 13 (Ref. 43, p. 2518). The Ra-226
mean plus two standard deviations from the 30 samples comprising BSA-24 was used as the background level for
AOC 13 (Ref. 200, p.2). The metals analysis was performed by ALS Environmental Laboratories using USEPA
method SW-846 6020A ICP-MS (Refs. 129, pp.2,73; 133, pp.2,35). Ra-226 analysis was performed by ALS
Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Refs. 129, pp.2,165; 133,
pp.2,75).
Table 17. Sample Description itiul Analytical Results lor AOC 13
S;t in pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 24)
29, p.32; 43,
p.2517
B24-
SS06-01-
071618
0-6"
Silty
sand
1807365-9
7/16/18
Uranium
(mg/kg)
1.9
0.011
43, p.6980;
117,
pp.6,37;
220, pp.389,
390
BSA-24
0-6"
Silty
sand
1807366
7/16/18
Radium-
226 (pCi/g)
2.06*
NA
43, pp.6977,
6978;117,
p. 10; 200,
p.4; 220,
p.395
AOC Sample - Mesa II Mine 4 Waste Pile
M29A and Burial Cell 43
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Table 17. Sample Description itiul Analytical Results lor AOC 13
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Re Terence
M29-
SS48-01-
092518
u-o"
Waste
rock
sand
lSluu:4-15
9.25.18
I rani mil
(mg/kg)
23
u.ul
29, p. 177,
129,
pp.7,73;
220, p.710
M29-
SS48-01-
092518
0-6"
Waste
rock
sand
1810024-15
9/25/18
Radium-
226 (pCi/g)
21.6
NA
29, p. 177;
129, p. 165;
220, pp.710,
711
AOC Sample - Mesa II Mine 4 Waste Pile
M29B
M29-
XS19-
01-
092518
0-3"
Waste
rock
sand
1810032-9
9/25/18
Uranium
(mg/kg)
11
0.0097
133,
pp.5,35;
220, pp.745,
746
M29-
XS19-
01-
092518
0-3"
Waste
rock
sand
1810033-9
9/25/18
Radium-
226 (pCi/g)
9.3
NA
133,
pp.8,75;
220, pp.750,
751
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 14
Name of AOC: Mesa II Pit Waste Pile M24 and Burial Cell 44
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 5 and Figure 6
AOC 14 comprises two waste piles: Mesa II Pit Waste Pile M24 and Burial Cell 44. Burial Cell 44 is located
within and upgradient of Waste Pile M24. These waste piles are aggregated into a single AOC because of their
proximity, wastes eroding into the same drainage, wastes coming from the same ore body, and the same mine
opening. Waste Pile M24 is a surficial waste pile that is 2.5 feet deep on average on a slope greater than
30 degrees (Ref. 24, pp.30,31). The waste pile has high erosion potential with sparse vegetation, and three
drainages cut through it (Ref. 24, pp.30,31,133). The waste generated is a result of mine operations in ore bodies
in the Salt Wash Member of the Lower Morrison Formation (Ref. 24, pp.22,23). The three onsite drainages
connect to the Cove Wash Middle 3 drainage located downgradient of the mine (Ref. 24, pp. 19,20). Surficial
contamination documented in the AOC sample results below shows that the waste piles do not have a
continuous cover of 2 feet or greater (Ref. 223, p.20).
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All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE
report as soil samples. Observed contamination is established by analytical significance above background levels.
For surface waste samples analyzed for metals, observed contamination is established when the metal
concentration is three times the highest background concentration. Background levels are determined based on
the highest analyte-specific background concentration from the AOC-specific background study area (Refs. 24,
p.33; 43, p.2515). For Ra-226, observed contamination is established when the Ra-226 concentration is two
standard deviations above the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp.
1-2). All Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g.
(Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174).
BSA-24 was selected as the most appropriate background location for AOC 14 because it is within the same
geologic unit (undifferentiated Summerville and Entrada Formations), it hosts soil of the same type, and it is the
closest BSA to the AOC (Ref. 24, p.32). The highest background concentration for each metals analyte from the
30 samples comprising BSA-24 was used as the background level for AOC 14 (Ref. 43, p. 2518). The Ra-226
mean plus two standard deviations from the 30 samples comprising BSA-24 was used as the background level for
AOC 14 (Ref. 200, p.2). The metals analysis was performed by ALS Environmental Laboratories using USEPA
method SW-846 6020A ICP-MS (Refs. 127, pp.2,41; 158, pp.2,61). Ra-226 analysis was performed by ALS
Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Ref. 158, pp.2,98).
Table IS. Sample Description ;mcl Analytical Result?
lor AOC 14
S;t in pie
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Re Terence
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
Background Samp
e (BSA 24)
24, p.33; 43,
pp.2515,
2517
B24-
0-6"
Silty
1807365-29
7/16/18
Arsenic
3.5
0.22
43, p.6982;
SS26-
sand
(mg/kg)
117,
01-
071618
pp.6,77;
220, pp.389,
390
B24-
0-6"
Silty
1807365-9
7/16/18
Uranium
1.9
0.011
43, p.6980;
SS06-
sand
(mg/kg)
117,
01-
pp.6,37;
071618
220, pp.389,
390
BSA-24
0-6"
Silty
sand
1807366
7/16/18
Radium-
226 (pCi/g)
2.06*
NA
43, pp.6977,
6978; 200,
p.2; 117,
p. 10; 220,
p.395
AOC Samples - Mesa II Pit Waste Pile M24 and Burial Cell 44
M24-
0-6"
Waste
1810003-14
9/25/18
Arsenic
32
0.21
24, p.203;
SS76-
rock
(mg/kg)
158,
01-
sand
pp.5,61;
092518
220, p.698
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Tsihlc IS. Siimplc Description ;mcl An;ilytic:il Results lor AOC 14
S:i m pic
II)
Siimplc
Depth
Soil
Type1
l.iihoriilory
Sitinplc 11)
Dsitc
1 hi/iirdous
Substiincc
1 hi/iirdous
Substiincc
Cone.
Reporting
Limit2
Reference
\ 124-
XS115-
01-
071418
(l-.V
\\ asle
rock
sand
1X073^-7
7 14 IS
I milium
(mg/kg)
i:
i) n| 1
127, pp.5,41
M24-
SS40-
02-
092518
0-6"
Waste
rock
sand
1810004-13
9/25/18
Radium-
226 (pCi/g)
41.2 M3
NA
24, p.206;
158,
pp. 12,98;
220, pp.704,
705
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC (Ref. 158, p.98).
Number by which this AOC is to be identified: 15
Name of AOC: Mesa II 1/4 Mine Waste Pile CO-07-NNWP01 and Waste Pile CO-07-NNWP02
AOC Type: Piles
Location and description of AOC (with reference to a map of the area): Figure 5 and Figure 6
AOC 15 comprises two waste piles: Mesa II 1/4 Mine Waste Pile CO-07-NNWP01 and Waste Pile CO-07-
NNWP02. These waste piles are aggregated into a single AOC because they are a continuation of the same pile
over a cliff and the waste came from the same underground workings. Waste Pile CO-07-NNWP01 was
consolidated during NAML reclamation efforts and is approximately 15 feet higher in elevation than Waste Pile
CO-07-NNWP02 (Ref. 82, p. 6). A diversion channel is located along the north side of Waste Pile CO-07-
NNWP01 (Ref. 82, p.6). Waste Pile CO-07-NNWP02 was reported as unreclaimed and sits on a bench.
Approximately 200 feet down slope of this bench, the mine area drops into a large sheer cliff band into a drainage
in the northeast. The mine area is located on 20- to 35-degree slopes above the cliff band (Ref. 82, p.6). Two
drainages are located within the Mesa II 1/4 Mine area. The waste generated is a result of mine operations in ore
bodies in the Salt Wash Member of the Lower Morrison Formation. Surficial contamination documented in the
AOC sample results below shows that the waste piles do not have a continuous cover of 2 feet or greater (Ref.
223, p.20).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
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three times the highest background concentration. For Ra-226, observed contamination is established when the
Ra-226 concentration is two standard deviations above the mean site-specific Ra-226 background concentration
(Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for this AOC also exceed the upper-limit range of regional
background of 2.23 pCi/g. (Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174).
The Morrison Formation BRA was chosen by Cyprus Amax to best represent the background levels for AOC 15
(Refs. 63, p.63; 82, p.8). The highest concentration of each metal analyte from all samples collected from the
Morrison Formation BRA was chosen as the background level (Refs. 1, p. 14, p. 116; 82, p.6; 63, pp.63,65). The
metals analysis was performed by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-
MS (Ref. 167, pp. 1467,1470). Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA
method 901.1 gamma spectroscopy (Ref. 167, p.1615).
Table 19. Sample Description :tiul Analytical Results lor AOC 15
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a nee
1 la/arilous
Su list a nee
Cone.
Reporting
Limit2
Reference
Background Sample (Background - Morrison Formation)
82, p.6;
Ref. 63,
p.65
SS-CO-
Bl-021-
1014201
7
0-6"
Unavai
lable
1710392-
23
10/14/17
Uranium
(mg/kg)
1.5
0.1
169,
p.1401
Morrison
Ra-226
0-6"
Unavai
lable
1710392
10/14/17
Radium-
226
(pCi/g)
1.39*
NA
200, p.2
AOC Sample - Mesa II1/4 Mine Waste Pile CO-07-NNWP01
SS-07-
NNWP0
1-001-
10102
0-6"
Waste
1810331-
16
10/10/18
Uranium
(mg/kg)
9.1
0.012
167,
p.1470
AOC Sample - Mesa II1/4 Mine Waste Pile CO-07_N1
\WP02
SS-07-
NNWP0
2-001-
10102
0-6"
Waste
rock
sand
1810331-
13
10/10/18
Uranium
(mg/kg)
6.8
0.0096
167,
p.1467
SS-07-
NNWP0
2-001-
10102
0-6"
Waste
rock
sand
1810331-
13
10/10/18
Radium-
226
(pCi/g)
4.85
NA
167,
p.1615
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
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NNN000920223
-------
Number by which this AOC is to be identified: 16
Name of AOC: Henry Phillips Mine Waste Pile Mil
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 5 and Figure 6
AOC 16 comprises one waste pile: Henry Phillips Mine Waste Pile Ml 1. This waste pile is 2 to 3 feet deep with a
slope greater than 50 percent in places (Ref. 11, p.27). The waste generated is a result of mine operations in ore
bodies in the Salt Wash Member of the Lower Morrison Formation (Ref. 11, pp.21,22). The waste pile drains to
the Cove Wash Middle 3A drainage. Surficial contamination documented in the AOC sample results below shows
that the waste pile does not have a continuous cover of 2 feet or greater (Ref. 223, p.20).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 11, p.30; 43, p. 1483). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
BSA-14 was selected as the most appropriate background location for AOC 16 because it is within the same
geologic unit (lower Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC
(Refs. 11, p. 19; 43, pp. 45,46,1463). The highest background concentration for each metals analyte from the 30
samples comprising BSA-14 was used as the background level for AOC 16 (Ref. 43, p. 1486). The Ra-226 mean
plus two standard deviations from the 30 samples comprising BSA-14 was used as the background level for AOC
10 (Ref. 200, p.2). The metals analysis was performed by ALS Environmental Laboratories using USEPA method
SW-846 6020A ICP-MS (Refs. 86, pp.2,35; 91, pp.2,99). Ra-226 analysis was performed by ALS Environmental
Laboratories using USEPA method 901.1 gamma spectroscopy (Ref. 86, pp.2,69).
Table 20. Sample Description itiul Analytical Results lor AOC l(>
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 14)
11, P-30; 43,
p.1485
B14-
SS15-01-
071518
0-6"
Silty
sand
1807353-18
7/15/18
Uranium
(mg/kg)
0.55
0.011
43, p.6896;
102,
pp.6,54;
220, pp.375,
376
BSA-14
0-6"
Silty
sand
1807354
7/15/18
Radium-
226 (pCi/g)
O
be
¦X-
NA
43, pp.6892,
6893; 102,
p. 10; 200,
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Table 20. Sample Description itiul Analytical Results
lor AOC 16
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Re Terence
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
p.2; 220,
p.383
AOC Sample - Henry Phillips Mine Waste Pile Mil
Ml 1-
0-3"
Waste
1807369-4
7/11/18
Uranium
230
0.098
86, pp.5,35
XS11-
rock
(mg/kg)
01-
sand
071118
Ml 1-
0-3"
Waste
1807370-4
7/11/18
Radium-
191 M3
NA
86, pp.9,69;
XS11-
rock
226 (pCi/g)
220, pp.413,
01-
sand
414
071118
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC (Ref. 86, p.69).
Number by which this AOC is to be identified: 17
Name of AOC: Billy Topaha Mine Waste Pile CO-03-CAWP01
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 5 and Figure 6
AOC 17 comprises one waste pile: Billy Topaha Mine Waste Pile CO-03-CAWP01. This sparsely vegetated
waste pile is located along the main bench in the southeast portion of the mine area with residual waste rock
extending into an inaccessible area (Ref. 83, p.4). The waste generated is a result of mine operations in ore bodies
in the Salt Wash Member of the Lower Morrison (Ref. 83, p.5). The waste pile drains to the eastern branch of the
Cove Wash Middle 3A drainage. Surficial contamination documented in the AOC sample results below shows
that the waste pile does not have a continuous cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 83, p.6; 63, p.65). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
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the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
The Morrison Formation BRA was chosen by Cyprus Amax to best represent the background levels for AOC 15
(Refs. 63, p.63; 82, p.8). The highest concentration of each metal analyte from all samples collected from the
Morrison Formation BRA was chosen as the background level (Ref. 63, p.63). The metals analysis was performed
by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Ref. 168, pp.79,1351). Ra-
226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Ref. 168, p.404).
Table 21. Sample Description itiul Analytical Results lor AOC 17
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a nee
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (Background - Morrison Formation)
83, p.6;
63, p.65
SS-CO-
Bl-008-
10142017
0-6"
Unava
ilable
1710392-9
10/14/17
Arsenic
(mg/kg)
2.2
0.2
169, pp.5,
1387
ss-co-
Bl-021-
10142017
0-6"
Unava
ilable
1710392-
23
10/14/17
Uranium
(mg/kg)
1.5
0.01
169, pp.5,
1401
Morrison
Ra-226
0-6"
Unava
ilable
1710392
10/14/17
Radium-
226 (pCi/g)
1.39*
NA
200, p.2;
AOC Samples - Billy Topaha Mine Waste
Pile CO-03 CAWP01
SS-03-
MS-002-
11102017
0-6"
Waste
1711255-1
11/10/17
Arsenic
(mg/kg)
9.77 (17J)
0.21
168,
p.7,79; 48,
p.20
SS-03-
CAWP01-
002-
09212018
0-6"
Waste
1809485-
13
9/21/18
Uranium
(mg/kg)
360
0.097
168,
pp.,1351
SS-03-
MS-002-
11102017
0-6"
Waste
1711255-
1DUP
11/10/17
Radium-
226 (pCi/g)
254 M3
NA
168,
pp.7,404
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
J The analyte was detected at the reported concentration; the quantitation is an estimate with unknown bias.
As a result, the concentration of this qualified data has been adjusted (Ref. 48, p. 7, 8).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC (Ref. 168, p. 404).
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Areas of Observed Contamination 18 to 21 - Mesa III
The Mesa III area includes four AOCs located at five mines.
Table 22. Mesa III AOCs
AOC
AOC
Mine Claim Names
RSE Waste Pile Names
No.
Type
18
Pile
Mesa II 1/2 Mine
Waste Pile M30; Burial Cell 48
19
Pile
Mesa III Mine; Mesa II 1/2 Mine 4
Waste Piles M31 and M32
20
Pile
Mesa III Northwest Mine
CO-08 CAWP01
21
Pile
Mesa III West Mine
CO-09 NNWP01
The mines in the Mesa III area were developed and operated in the 1950s and 1960s by F.A. Sitton, the Navajo
Uranium Mining Company, Kerr-McGee (a predecessor of Tronox), and VCA. Operations included underground
mining that tapped paleochannels in the Salt Wash Member of the Lower Morrison Formation that are rich in
uranium and vanadium (Refs. 30, pp.23,30; 31, pp.23,26; 32, pp.24,27; 80, pp. 1,5; 81, pp. 1,5). Underground mine
workings exist throughout the Mesa III area. Waste piles consist of overburden or lower grade protore discarded
near or downslope of portals (Refs. 30, pp.27,28,32; 31, pp.27,31; 32, pp.28,29,33; 80, p.4; 81, p.4).
Number by which this AOC is to be identified: 18
Name of AOC: Mesa II 1/2 Mine Waste Pile M30 and Burial Cell 48; NA-0313
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 7 and Figure 8
AOC 18 comprises two waste piles: Mesa II 1/2 Mine Waste Pile M30 and Burial Cell 48. The two waste piles
are aggregated together into a single AOC because the waste is from the same mine operation and workings.
Waste Pile M30 is approximately 7.5 feet deep on a slope greater than 45 degrees. Waste Pile M30 contains larger
boulders and is highly erodible with a fork of the Cove Wash Middle 2B drainage running directly through it
(Ref. 30, pp.32,33). The waste pile extends into NA-0313, a nearby mine-related feature that is an area of concern
for future investigation. Offsite migration at Waste Pile M30 has been documented and likely flows down to the
Cove Wash Middle 2B drainage north of the mine (Ref. 30, p. 133). Reclamation work was performed at Mesa II
1/2 Mine in 2001 by NAML as part of the NA-0313 Cove 3 Phase II reclamation project. Waste material was
excavated and placed into Burial Cell 48 and covered with 1.5 feet of nearby borrow material. The burial cell is
located upgradient of Waste Pile M30 (Ref. 30, pp.30,33). The waste generated is a result of mine operations in
ore bodies in the Salt Wash Member of the Lower Morrison Formation (Ref. 30, pp.23,24). Surficial
contamination documented in the AOC sample results below shows that the waste piles do not have a continuous
cover of 2 feet or greater. The underground workings of Mesa II 1/2 Mine connect to the workings at Mesa I 3/4
Incline and Mesa II Mine No. 1 & 2, P-21, beneath the mesa (Refs. 25, pp.27,28; 27, p.27; 30, p.28).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
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three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 30, p.35; 43, p.3035). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
BSA-30 was selected as the most appropriate background location for AOC 18 because it is within the same
geologic unit (lower Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC
(Ref. 43, pp. 45,46,3015,3018). The highest background concentration for each metals analyte from the 30
samples comprising BSA-30 was used as the background level for AOC 18 (Ref. 43, p.3038). The Ra-226 mean
plus two standard deviations from the 30 samples comprising BSA-30 was used as the background level for AOC
18 (Ref. 200, pp.2). The metals analysis was performed by ALS Environmental Laboratories using USEPA
method SW-846 6020A ICP-MS (Refs. 86, pp.2,43; 91, pp.2,55). Ra-226 analysis was performed by ALS
Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Ref. 86, pp.2,77).
Table 23. Sample Description itiul Analytical Results lor AOC IS
Nil m pic
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a lice
1 la/arilous
Su list a lice
Cone.
Reporting
Limit2
Reference
Background Samp
e (BSA 30)
30, p.35;
43, pp.
3035, 3037
B30-
SS19-
01-
071018
0-6"
Sand
1807262-22
7/10/18
Arsenic
(mg/kg)
2.1
0.2
43, p.7025;
126, pp.6,
64; 220,
pp.279,280
B30-
SS30-
01-
071018
0-6"
Sand
1807262-34
7/10/18
Uranium
(mg/kg)
0.67
0.0091
43, p.7026;
126, pp.6,
88; 220,
pp.279,281
BSA-30
0-6"
Sand
1807263
7/10/18
Radium-226
(pCi/g)
0.89*
NA
43, pp.
7020,
7021; 200,
p.2; 126,
p. 10; 220,
p.287
AOC Samples - Mesa II Vz
Mine Waste Pi
e M30 and Burial Cell
18; NA-0313
M30-
SS167-
01-
092918
0-6"
Silty
sand
1810124-3
9/29/18
Arsenic
(mg/kg)
7.8
0.19
30, p.219;
91, pp.7,
55; 220,
pp.824,
825
M30-
XS127-
01-
071618
0-3"
Waste
rock
sand
1807369-9
7/16/18
Uranium
(mg/kg)
360
0.1
86, pp.5,43
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T:iblc 23. Sample Description itiul \n;ilv(ic:il Results lor AOC IS
Nil m pic
Siiniple
Soil
II)
Depth
Type1
\13U-
n-3"
Waste
XS127-
rock
01-
sand
071618
l.iihoriilorv
S;t in pie II)
Dsitc
I hi/iirilous
Suhsl since
I l;i/;irilous
Suhsl since
Cone.
Reporting
Limit2
Reference
lS()737()-w
7 IS
Radium-"1 "Vi
(pCi/g)
115 _\13
\A
SO
pp.9,77;
220, p.413
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC (Ref 86, p.77).
Number by which this AOC is to be identified: 19
Name of AOC: Mesa II 1/2, Mine 4 Waste Pile M31; Mesa III Mine Waste Pile M32
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 7 and Figure 8
AOC 19 comprises two waste piles: Mesa II 1/2, Mine 4 Waste Pile M31 and Mesa III Mine Waste Pile M32. The
two waste piles are aggregated into a single AOC because they abut one another, have similar waste
characteristics, and are the result of mining the same mine workings. Waste Pile M31 is vegetated; however, a
small drainage bisects a section of the waste pile and continues through to the Mesa III Mine and subsequently
into the headwaters of the Cove Wash Middle 2B drainage (Refs. 31, pp.31,32; 32, pp.33,34). Offsite migration of
contaminants from Waste Pile M32 into the Cove Wash Middle 2B drainage was observed. Mesa II 1/2, Mine 4 is
upgradient of Mesa III Mine and is likely a contributor to contaminant migration seen at both mines (Refs. 31,
p.32; 32, p. 135). The waste generated is a result of mine operations in ore bodies in the Salt Wash Member of the
Lower Morrison Formation. Surficial contamination documented in the AOC sample results below shows that the
waste piles do not have a continuous cover of 2 feet or greater. The underground workings of Mesa III Mine
extend northwest of the mine (Refs. 31, p.32; 32, pp.28,29).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 31, p.34; 32, p.36; 43,
pp.3035,3142). For Ra-226, observed contamination is established when the Ra-226 concentration is two standard
deviations above the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All
Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1,
pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174).
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BSA-30 was selected as the most appropriate background location for Mesa II 1/2, Mine 4 Waste Pile M31
because it is within the same geologic unit (lower Morrison Formation), it hosts soil of the same type, and it is the
closest BSA to the AOC (Ref. 31, p. 33). BSA-31 was selected as the most appropriate background location for
Mesa III Mine Waste Pile M32 because it is within the same geologic unit (lower Morrison Formation), it hosts
soil of the same type, which is different from Waste Pile M31 (Ref. 32, p. 35). The highest background
concentration for each metals analyte from the 30 samples comprising each BSA was used as the background
level for its respective AOC (Refs. 31, p.75; 32, p.78). It is important to note that all metals analytes in AOC
samples exceed 3 times the highest analyte-specific background sample concentration from both BSAs. The Ra-
226 mean plus two standard deviations from the 30 samples comprising BSA-30 and BSA-31 was used as the
background level for Waste Piles M31 and M32, respectively (Ref. 200, pp.2). The metals analysis was performed
by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Ref. 91, pp.2,67,85). Ra-
226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Ref. 91, pp.2,180,198).
Table 24. Sample Description iincl Analytical Results lor AOC l()
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
Background Sample (BSA 30)
31, P-34;
43, pp.
3035, 3037
B30-
0-6"
Silty
1807262-34
7/10/18
Uranium
0.67
0.0091
43, p.7026;
SS30-01-
sand
(mg/kg)
126,
071018
pp.6,88;
220, pp.
279,281
BSA-30
0-6"
Silty
sand,
sand
1807263
7/10/18
Radium-
226 (pCi/g)
0.89*
NA
43,
pp.7020,
7021; 200,
p.2; 126,
p. 10; 220,
p.287
AOC Sample - Mesa II1/2, Mine 4 Waste Pile M31
M31-
0-6"
Silty
1810124-9
9/29/18
Uranium
27
0.0097
31, p.185;
SS37-01-
sand
(mg/kg)
91,
092918
pp.7,67;
220, pp.
824,825
M31-
0-6"
Silty
1810125-9
9/29/18
Radium-
11
NA
31, p.185;
SS37-01-
sand
226 (pCi/g)
91,
092918
pp.15,180;
220, pp.
834,835
Background Sample (BSA 31)
32, p.36;
43, p.3144
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Table 24. Sample Description itiul Analytical Results lor AOC l()
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
1331-
SS09-01-
071318
u-o"
Sand
1SU7325-13
7.13.18
I rani mil
(mg/kg)
1
u.ull
43,p.7u31,
135, pp.6,
47; 220,
pp.311,
312
BSA-31
0-6"
Silty
sand
1807326
7/13/18
Radium-
226 (pCi/g)
1.62*
NA
43,
pp.7028,
7029;135,
p.11; 200,
p.2; 220,
p.319
AOC Sample - Mesa III Mine Waste Pile M32
M32-
SS89-01-
092918
0-6"
Silty
sand
1810124-18
9/29/18
Uranium
(mg/kg)
440
0.099
32, p.210;
91,
pp.7,85;
220,
pp.824,
825
M32-
SS89-01-
092918
0-6"
Silty
sand
1810125-18
9/29/18
Radium-
226 (pCi/g)
141 M3
NA
32, p.210;
91,
pp.15,198;
220, p.834
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC (Ref. 91, p. 198).
Number by which this AOC is to be identified: 20
Name of AOC: Mesa III, Northwest Mine Waste Pile CO-08_CAWP01
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 7 and Figure 8
AOC 20 comprises one waste pile: Mesa III, Northwest Mine Waste Pile CO-08_CAWP01. This waste pile is
located near the center of a bench that runs through the south-central portion of the mine area and extends
downslope into inaccessible areas. The mine is on 20- to 35-degree slopes and upgradient of the Cove Wash
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Middle 2A drainage to the northwest (Ref. 80, p.4). The waste generated is a result of mine operations in ore
bodies in the Salt Wash Member of the Lower Morrison Formation. Surficial contamination documented in the
AOC sample results below shows that the waste pile does not have a continuous cover of 2 feet or greater (Ref.
223, p.20).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 80, p.5; 63, p.65). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
The Morrison Formation BRA was chosen by Cyprus Amax to best represent the background levels for AOC 20
(Refs. 63, p.63; 82, p.8). The highest concentration of each metal analyte from all samples collected from the
Morrison Formation BRA was chosen as the background level (Ref. 63, p.63). The metals analysis was performed
by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Ref. 165, pp.447). Ra-226
analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy
(Ref. 165, pp.547).
Table 25. Sample Description iincl Analytical Results lor AOC 20
S:i m pic
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 lazarilous
Su list a lice
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (Background - Morrison Formation)
80, p.5;
63, p.65
SS-CO-
Bl-021-
1014201
7
0-6"
Unava
ilable
1710392-
23
10/14/17
Uranium
(mg/kg)
1.5
0.01
169,
pp.5,1401
Morrison
Ra-226
0-6"
Unava
ilable
1710392
10/14/17
Radium-
226 (pCi/g)
1.39*
NA
200, p.2;
AOC Sample - Mesa III, Northwest Mine Waste Pile CO-08CAWP01
SS-08-
CAWP01
-001-
06082
0-6"
Waste
1806287-8
6/8/18
Uranium
(mg/kg)
480
0.099
165,
pp.13,447
SS-08-
CAWP01
-001-
06082
0-6"
Waste
1806287-8
6/8/18
Radium-
226 (pCi/g)
158 M3
NA
165,
pp.547
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
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NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC (Ref. 165, p. 547).
Number by which this AOC is to be identified: 21
Name of AOC: Mesa III, West Mine Waste Pile CO-09_NNWP01
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 7 and Figure 8
AOC 21 comprises one waste pile: Mesa III, West Mine Waste Pile CO-09_NNWP01. This waste pile is located
on a small cut bench in the central portion of the mine area and extends into steep inaccessible areas. The mine is
located on 20- to 45-degree slopes (Ref. 81, pp.4,5,21). The waste generated is a result of mine operations in ore
bodies in the Salt Wash Member of the Lower Morrison Formation. Surficial contamination documented in the
AOC sample results below shows that the waste piles do not have a continuous cover of 2 feet or greater. The
Mesa III, West Mine sits upgradient of the Cove Wash Middle 2A drainage (Ref. 32, p.22).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 81, p.5; 63, p.65). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
The Morrison Formation BRA was chosen by Cyprus Amax to best represent the background levels for AOC 21
(Refs. 63, p.63; 82, p.8). The highest concentration of each metal analyte from all samples collected from the
Morrison Formation BRA was chosen as the background level (Ref. 63, p.63). The metals analysis was performed
by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Ref. 166, pp. 125,524). Ra-
226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Ref. 166, p.451).
Table 26. Sample Description itiul Analytical Results lor AOC 21
S:i m pic
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a lice
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (Background - Morrison Formation)
81, P-5;
63, p.65
SS-CO-
Bl-008-
1014201
7
0-6"
Unava
ilable
1710392-9
10/14/17
Arsenic
(mg/kg)
2.2
0.2
169, p.
1387
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Table 26. Sample Description and Analytical Results lor AOC 21
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
ss-co-
Bl-021-
1014201
7
u-o"
I na\ a
ilable
1710392-23
10.14.17
I rani mil
(mg/kg)
1.5
0.01
109,
p.1401
Morrison
Ra-226
0-6"
Unava
ilable
1710392
10/14/17
Radium-
226 (pCi/g)
1.39*
NA
200, p.2;
AOC Sample - Mesa III, West Mine Waste Pile CO-09_NNWP01
SS-09-
NNWPO
1-002-
10152
0-6"
Waste
1810423-5
10/15/18
Arsenic
(mg/kg)
10
0.22
166, p.13
,524
SS-09-
MS-005-
1023201
7
0-6"
Waste
1710526-6
10/23/17
Uranium
(mg/kg)
41
0.01
166,
pp.13,
14,125
SS-09-
MS-005-
1023201
7
0-6"
Waste
1710526-6
10/23/17
Radium-
226 (pCi/g)
62.4 M3
NA
166,
pp.13,14,
451
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC (Ref. 166, p. 451).
Description of Areas of Concern - Mesa III
Given the interconnected nature of the ore bodies, similar mining processes, similar time frames of operation,
and general geology of the LMMD site, the possible mining-related sources listed below are likely to be
releasing hazardous substances to the Cove Wash drainages or exposing human or terrestrial sensitive
environment targets. These other areas of concern will be evaluated during further investigation.
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Table 27. Mesa III Oilier Areas of Concern
Oilier
Areas of
Concern
Description (Reference)
CovOOO
CovOOO is located slightly north and east of Mesa III, Northwest Mine (Figure 1). CovOOO
inventory lists one rimstrip and one pit. No waste piles are recorded at CovOOO. The mine was
listed as operational in 1966 (Ref. 52, p. 4, 6). Weston Solutions Inc. (Weston) conducted a
gamma scan in 2010, and the highest gamma measurement was 20,696 counts per minute
(cpm). The highest background gamma level measured was 9,123 cpm (Ref. 52, p. 3, 9, 10).
Mesa IV, East
Side
Mesa IV, East Side is located northwest of Mesa III Mine and southwest of Mesa III,
Northwest Mine (Ref. 23, p. 20, 24). The mine sits upgradient of the Cove Wash Middle 2A
drainage (Ref. 23, p. 20). The mine is listed as having two waste piles, one rimstrip, and one
pit. A small waste pile is located in the western portion of the mine area, and a larger waste
pile is located in the northern portion of the mine area. The northern waste pile extends south
through the mine area and east over a steep cliff (Ref. 50, p. 4, 6). Weston conducted a
gamma scan in 2010, and the highest gamma measurement was 119,566 cpm, which is
significantly higher than the highest background gamma level measurement of 11,150 cpm
(Ref. 50, p. 3, 10, 11).
Areas of Observed Contamination 22 to 28 - Mesa IV
The Mesa IV area includes seven AOCs located at 14 mines and mine-related areas.
Table 2S. Mesa IV AOCs
AOC
No.
AOC
Type
Mine Claim Names
RSI! Waste Pile Names
22
Pile
Mesa IV Mine No. 1;
Mesa IV Mine No. 3
Waste Piles M20A, M20B, M22A, M22B, M22C; Burial Cell 56
23
Pile
Mesa IV Mine No. 2
Waste Piles M21A, M21B, M21C, M21D, M21E, and M21F;
Burial Cell 63
24
Pile
Mesa IV West Mine
Waste Pile M23; Burial Cell 70b
25
Pile
Mesa IV % Mine
CO-10 NNWP01
26
Pile
South Portal, Frank No. 1
Mine; East Portal, Frank
No. 1 Mine; North
Portal, Frank No. 1
Mine; Frank No. 2; Mesa
IV 1/2 Mine and
Simpson 181; Mesa V
Mine - 508
CO-05 NNWP14, CO-05 NNWP15. CO-05 NNWP16,
CO-05 NNWP17, CO-05 NNWP18, and CO-05 NNWP19,
CO-05 NNWP05, CO-05 NNWP06, CO-05 NNWP07,
CO-05 NNWP08, CO-05 NNWP09, CO-05 NNWP 10,
CO-05 NNWP11, CO-05 NNWP 12, and CO-05-NNWP13,
CO-05 NNWP01, CO-05 NNWP02, CO-05 NNWP03, and
C0-05_NNWP04, CO-06_NNWP01; Waste Piles M18 and M19;
Burial Cells 86b and 87a
27
Pile
NA-0316
CO-11 NNWP01, CO-11 NNWP02, and CO-11 NNWP03
28
Pile
Cov087
Cov087 Waste Pile
All mines in the Mesa IV area were either developed and operated by F.A. Sitton, the Navajo Uranium Mining
Company, Kerr-McGee and VCA or by the Climax Uranium Company in the 1950s and 1960s (Refs. 18, p.26;
19, p.27; 20, p.27; 21, p.26; 22, p.25; 23, p.25; 76, p.l; 77, p.l; 78, pp.1; 79, p.l). Two additional mine-related
areas—Cov087 and Cov068—are also within the Mesa IV area. Operations included underground mining that
tapped paleochannels in the Salt Wash Member of the Lower Morrison Formation that are rich in uranium and
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vanadium (Refs. 18, pp.23,24; 19, pp.24,25; 20, pp.23,25; 21, pp.23,24; 22, pp.22,23; 23, pp.22,23; 76,
pp.41,42,43,50,51,52; 77, pp.22,25; 78, pp.24,27; 79, pp.21,24). Underground mine workings exist throughout the
Mesa IV area. Waste piles consist of overburden or lower grade protore discarded near or downslope of portals
(Refs. 18, pp.27,30; 19, pp.28,32; 20, pp.29,33; 21, pp.27,31; 22, pp.26,29; 23, pp.26,30; 76,
pp.41,42,43,50,51,52; 77, pp.22,25; 78, pp.24,27; 79, pp.21,24).
Number by which this AOC is to be identified: 22
Name of AOC: Mesa IV Mine No. 1 Waste Pile M20A, Waste Pile M20B, and Burial Cell 56; Mesa IV Mine
No. 3 Waste Pile M22A, Waste Pile M22B, and Waste Pile M22C
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 9 and Figure 11
AOC 22 comprises six waste piles: Mesa IV Mine No. 1 Waste Pile M20A, Waste Pile M20B, and Burial Cell 56;
and Mesa IV Mine No. 3 Waste Pile M22A, Waste Pile M22B, and Waste Pile M22C (Refs. 20, p.29; 22, p.26).
All waste piles are aggregated into a single AOC because of their proximity, similar waste type, same AOC type,
impacts on the same targets, and similar past operational history. Within Mesa IV Mine No. 1, Waste Pile M20A
is in the northeastern portion and Waste Pile M20B is in the southwestern portion. Waste Pile M20B is shallower
than Waste Pile M20A. Drainage and erosional features are present on Waste Pile M20A. Both waste piles have
potential to erode and transport material into the Cove Wash Middle 2A drainage in the canyon below. Burial Cell
56 is located below the highwall and contains material from Waste Pile M20A (Ref. 20, pp.29,33,137). Within
Mesa IV Mine No. 3, Waste Pile M22A is in the eastern portion, Waste Pile M22B is in the center, and Waste
Pile M22C is in the western portion. The highest portion of the mine is near Waste Pile M22C with the area
sloping down and to the east. Drainages were mapped on Waste Pile M22A and Waste Pile M22B. Unreclaimed
Waste Piles M22a and M22B have the potential to erode and transport material into the Cove Wash Middle 2A
drainage located east and downgradient of the mine. Waste Pile M22C is eroding into the Cove Wash Middle 1G
drainage located to the west (Ref. 22, pp.26,29,130). The waste generated is a result of mine operations in ore
bodies in the Salt Wash Member of the Lower Morrison Formation. Surficial contamination documented in the
AOC sample results below shows that the waste piles do not have a continuous cover of 2 feet or greater (Ref.
223, p.20).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 20, p.36; 22, p.32; 43,
pp.2515,2619). For Ra-226, observed contamination is established when the Ra-226 concentration is two standard
deviations above the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All
Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1,
pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174).
Because AOC 22 waste piles are spread across two geologies, both BSA-24 and BSA-25 are appropriate BSAs
for the AOC. BSA-25 is the most appropriate BSA for waste piles M20A, M20B, and Burial Cell 56, while BSA-
24 is the most appropriate BSA for waste piles M22A, M22B, and M22C (Ref. 43, pp. 2518,2521,2622,2625).
The BSAs were chosen because of their comparability to their underlying geologies and surface soil types (Refs.
43, pp. 2518,2521,2622,2625). The Ra-226 mean plus two standard deviations from the 30 samples comprising
BSA-24 was used as the background level for waste piles M22A-C while the same was done for BSA-5 and waste
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piles M20A, M20B, and Burial Cell 56 (Ref. 200, p.2). The metals analysis was performed by ALS
Environmental Laboratories using USEPAmethod SW-846 6020A ICP-MS (Refs. Ill, pp.2,57,75,81; 116,
pp.2,110,118; 123, pp.2,49; 136, pp.2,55). Ra-226 analysis was performed by ALS Environmental Laboratories
using USEPA method 901.1 gamma spectroscopy (Refs. Ill, pp.2,124,140,146; 116, pp.2,201; 123, pp.2,137).
Table 29. Sample Description iincl Analytical Results lor AOC 22
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a nee
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 25)
20, p.36;
43, p.2621
B25-
SS04-01-
060418
0-6"
Silty
sand
1806160-23
6/4/18
Uranium
(mg/kg)
2.5
0.01
43, p.
6988;118,
pp.6, 66;
220, pp.
190,191
BSA-25
0-6"
Silty
sand
1806159
6/4/18
Radium-
226 (pCi/g)
2.65*
NA
43,
p.6986;
200, p.2;
118, p.l 1;
220, p.182
AOC Sample - Mesa IV Mine No. 1 Waste
Pile M20A and Burial Cell 56
M20-
SS147-01-
091718
0-6"
Sandy
silt
1809477-35
9/17/18
Uranium
(mg/kg)
370
1
20, p.248;
116, pp.5,
110; 220,
pp. 888,
890
M20-
SS147-01-
091718
0-6"
Sandy
silt
1809478-35
9/17/18
Radium-
226 (pCi/g)
278 M3
NA
20, p.248;
116, pp.
17, 201;
220, pp.
658,660
AOC Samples - Mesa IV Mine No. 1 Waste Pile M20B
M20-
SS394-01-
091718
0-6"
Silty
sand
1809477-39
9/17/18
Uranium
(mg/kg)
97
0.99
20, p.252;
116, p.5,
118; 220,
pp.888,
890
M20-
XS365-
02-
060618
0-3"
Waste
rock
sand
1806222-19
6/6/18
Radium-
226 (pCi/g)
65.8
NA
HI, P-6,
124; 220,
pp.221,
222
Background Sample (BSA 24)
43, p.
2515; 22,
P.32;
B24-
SS26-01-
071618
0-6"
Silty
sand
1807365-29
7/16/18
Arsenic
(mg/kg)
3.5
0.22
43, p.
6982; 117,
pp.6, 77;
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Table 2(). Sample Description itiul Analytical Results lor AOC 22
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a nee
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
220,
pp.389,
390
B24-
SS06-01-
071618
0-6"
Silty
sand
1807365-9
7/16/18
Uranium
(mg/kg)
1.9
0.011
43, p.
6980;117,
pp.6, 37;
220, pp.
389, 390
BSA-24
0-6"
Silty
sand
1807366
7/16/18
Radium -
226 (pCi/g)
2.06*
NA
43, pp.
6977,
6978;117,
p.10; 200,
p.2; 220,
p.395
AOC Sample - Mesa IV Mine No. 3 Waste
Pile M22A
M22-
XS112-
01-
091418
0-3"
Waste
rock
sand
1809475-14
9/14/18
Uranium
(mg/kg)
17
0.0097
22, p.180;
123, pp.6,
49; 220,
pp.627,
628
M22-
XS112-
01-
091418
0-3"
Waste
rock
sand
1809476-14
9/14/18
Radium -
226 (pCi/g)
12.2
NA
22, p.180;
123, pp.
11,137;
220, pp.
637,638
AOC Samples - Mesa IV Mine No. 3 Waste Pile M22B
M22-
SS60-01-
091718
0-6"
Gra-
vel
1809418-11
9/17/18
Arsenic
(mg/kg)
17
0.18
22, p.188;
136, pp.5,
55; 220,
pp.566,
567
M22-
XS60-01-
060418
0-3"
Waste
rock
sand
1806235-30
6/4/18
Uranium
(mg/kg)
67
0.0098
22, p. 171;
111, pp.6,
81; 220,
pp.235,
236
M22-
XS60-01-
060418
0-3"
Waste
rock
sand
1806222-30
6/4/18
Radium-
226 (pCi/g)
39.3*
NA
22, p. 171;
111, pp.
12,146;
220, pp.
221,222
AOC Sample - Mesa IV Mine No. 3 Waste
Pile M22C
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Tsihlc 2(). Siimplc Description itiul \n;ilv(ic:il Results lor AOC 22
S:i m pic
II)
Sum pic
Depth
Soil
Type1
l.iihoriilorv
S:i in pic 11)
Diitc
1 l;i/;iriloiis
Suhsl since
1 l;i/;irdous
Siibsl:incc
Cone.
Reporting
Limit2
Reference
m::-
XS14-01-
060418
n-3"
\\ ask-
rock
sand
181X035-^7
6 4 IS
Arsenic
(mg/kg)
lb
n:
-_,p-175,
111, pp.6,
75; 220,
pp.235,
236
M22-
XS14-01-
060418
0-3"
Waste
rock
sand
1806235-27
6/4/18
Uranium
(mg/kg)
14
0.0099
22,p.175;
111, pp.6,
75; 220,
pp.235,
236
M22-
XS14-01-
060418
0-3"
Waste
rock
sand
1806222-27
6/4/18
Radium-
226 (pCi/g)
12.9
NA
22,p.175;
111, pp.
12,140;
220, pp.
221,222
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC.
Number by which this AOC is to be identified: 23
Name of AOC: Mesa IV Mine No. 2 Waste Pile M21A, Waste Pile M21B, Waste Pile M21C, Waste Pile M21D,
Waste Pile M21E, Waste Pile M21F, and Burial Cell 63
AOC Type: Pile
Location and description of AOC (with reference to a map of the mine): Figure 9 and Figure 11
AOC 23 comprises seven waste piles: Mesa IV Mine No. 2 Waste Pile M21A, Waste Pile M21B, Waste Pile
M21C, Waste Pile M21D, Waste Pile M21E, Waste Pile M21F, and Burial Cell 63 (Ref. 21, p.27). All waste piles
are aggregated into a single AOC because of their proximity, similar waste type, same AOC type, impacts on the
same targets, and similar past operational history. Waste Piles M21A and M21B have the greatest volume of
waste material remaining in the AOC. Both waste piles have an average approximate depth of 5 feet and are
located on slopes greater than 30 degrees. Waste Piles M21A and M21B are highly erodible, and offsite migration
has been documented with waste material transported to the Cove Wash Middle 2 drainage. Waste Piles M21C,
M21D, and M21E have an average depth of 3 feet and are on a steep slope. These waste piles are also highly
erodible, and offsite migration has been documented with waste material transported to the Cove Wash Middle
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1G drainage. Waste Pile M21F encompasses Burial Cell 63. Waste Pile M21F has an average depth of 2 feet on a
slope greaterthan 30 degrees (Ref. 21, pp.31,32,134,137). The waste generated is a result of mine operations in
ore bodies in the Salt Wash Member of the Lower Morrison Formation. Surficial contamination documented in
the AOC sample results below shows that the waste piles do not have a continuous cover of 2 feet or greater (Ref.
223, p. 20).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 21, p.35; 43, p.2515). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
BSA-24 was selected as the most appropriate background location for AOC 23 because it is within the same
geologic unit (undifferentiated Summerville and Entrada Formations) and it hosts soil of the same type (Ref. 21,
pp. 23,24,34; 43, pp.2495,2498). The metals analysis was performed by ALS Environmental Laboratories using
USEPA method SW-846 6020A ICP-MS (Refs. 119, pp.2,45; 120, pp.2,72,76; 121, pp.2,50; 122, pp.2,44). Ra-
226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Refs. 119, pp.2,96; 120, pp.2,150,154; 121, pp.2,83; 122, pp.2,85).
Table 30. Sample Description itiul Analytical Results lor AOC 23
Sample
II)
Samplc
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a nee
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 24)
21, p.35;
43, p.2517
B24-
SS06-01-
071618
0-6"
Silty
sand
1807365-9
7/16/18
Uranium
(mg/kg)
1.9
0.011
43,p.6980;
117, pp.6,
37; 220,
pp.389,
390
BSA-24
0-6"
Silty
sand
1807366
7/16/18
Radium-
226 (pCi/g)
2.06*
NA
43,
pp.6977,
6978;117,
p.10; 200,
p.2; 220,
p.395
AOC Sample - Mesa IV Mine No. 2 Waste
Pile M21A
M21-
SS434-
01-
091218
0-6"
Waste
rock
sand
1809283-5
9/12/18
Uranium
(mg/kg)
630
0.49
21, p.279;
119, pp.6,
45; 220,
pp.896,
897
M21-
SS434-
0-6"
Waste
rock
sand
1809284-5
9/12/18
Radium-
226 (pCi/g)
307 M3
NA
21, p.279;
119, pp.
13,96;
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Table 30. Sample Description itiul Analytical Results lor AOC 23
S;t in pie
II)
Sa in pie
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/ardous
Su list a nee
1 la/ardous
Substance
Cone.
Reporting
Limit2
Reference
01-
091218
220, pp.
479,480
AOC Sample - Mesa IV Mine No. 2 Waste
Pile M21B
M21-
XS503-
01-
091218
0-3"
Waste
rock
sand
1809473-28
9/12/18
Uranium
(mg/kg)
66
0.0094
21, p.266;
120, pp.6,
76; 220,
pp.611,
312
M21-
XS503-
01-
091218
0-3"
Waste
rock
sand
1809474-28
9/12/18
Radium -
226 (pCi/g)
47.3
NA
21, p.266;
120, pp.
10,154;
220, pp.
619, 620
AOC Sample - Mesa IV Mine No. 2 Waste
Pile M21C
M21-
XS323-
01-
091218
0-6"
Waste
rock
sand
1809473-26
9/12/18
Uranium
(mg/kg)
38
0.0093
21, p.273;
120, pp.6,
72; 220,
pp.611,
612
M21-
XS323-
01-
091218
0-6"
Waste
rock
sand
1809474-26
9/12/18
Radium-
226 (pCi/g)
34.3
NA
21, p.273;
120, pp.
10,150;
220, pp.
619, 620
AOC Sample - Mesa IV Mine No. 2 Waste
Mle M21D and Waste Pi
e M21E
M21-
SS280-
01-
091718
0-6"
Silty
Sand
1809424-9
9/17/18
Uranium
(mg/kg)
17
0.01
21, p.284;
121, pp.5,
50; 220,
pp.576,
577
M21-
SS280-
01-
091718
0-6"
Silty
Sand
1809425-9
9/17/18
Radium-
226 (pCi/g)
15.4
NA
21, p.284;
121, pp.
12,83;
220, pp.
581, 582
AOC Sample - Mesa IV Mine No. 2 Waste
Pile M21F and Burial Cell 63
M21-
XS403-
01-
060818
0-3"
Waste
rock
sand
1806234-16
6/8/18
Uranium
(mg/kg)
81
0.0097
21, p.267;
122, pp.5,
44; 220,
pp.231,
232
M21-
XS403-
0-3"
Waste
rock
sand
1806224-16
6/8/18
Radium-
226 (pCi/g)
71.3
NA
21, p.267;
122, pp.9,
85; 220,
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Tsihle 30. Siimple Description itiul Aiiiilvticiil Results lor AOC 23
S;t in pie
II)
Siimple
Depth
Soil
Type1
l.iihomtorv
Siimple 11)
Diite
1 lii/iirilous
Subsist n cc
1 lii/iirilous
Subsliince
Cone.
Reporting
Limit2
Reference
01-
060818
pp.227,
228
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC (Ref. 119, p. 96).
Number by which this AOC is to be identified: 24
Name of AOC: Mesa IV, West Mine Waste Pile M23 and Burial Cell 70b
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 10 and Figure 11
AOC 24 comprises two waste piles: Mesa IV, West Mine Waste Pile M23 and Burial Cell 70b. Both waste piles
are aggregated into a single AOC because of their proximity, similar waste type, same AOC type, impacts on the
same targets, and similar past operational history. Waste Pile M23 lies below a 20-foot cliff in the western portion
of the mine area and has a depth of approximately 5 feet on a slope greater than 30 degrees. A drainage transects
Waste Pile M23 and connects to the Cove Wash Middle 1 drainage downgradient of the mine. Burial Cell 70b is
located upgradient of Waste Pile M23 (Ref. 23, pp.26,30). The waste generated is a result of mine operations in
ore bodies in the Salt Wash Member of the Lower Morrison Formation (Ref. 23, pp.22,23). Surficial
contamination documented in the AOC sample results below shows that the waste piles do not have a continuous
cover of 2 feet or greater (Ref. 223, p. 20).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 23, p.33; 43, p.2722). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
BSA-26 was selected as the most appropriate background location for AOC 24 because it is within the same
geologic unit (Morrison Formation), it hosts soil of the same type, and it's the closest BSA to the AOC (Refs. 23,
pp. 22,23,32; 43, pp. 2702,2705). The metals analysis was performed by ALS Environmental Laboratories using
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USEPA method SW-846 6020A ICP-MS (Ref. 124, pp.2,25). Ra-226 analysis was performed by ALS
Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Ref. 124, pp.2,38).
Table 31. Sample Description itiul Analytical Results lor AOC 24
S:i m pic
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 lazarilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 26)
23, p.33;
43, p.2724
B26-
SS27-01-
060518
0-6"
Clayey
sand
1806162-16
6/5/18
Uranium
(mg/kg)
16
0.011
43, p.6998;
125, pp.6,
53; 220,
pp.206,
207
BSA-26
0-6"
Silty
sand
1806161
6/5/18
Radium-
226 (pCi/g)
11.02*
NA
43, pp.
6993,
6994; 200,
p.2; 125,
p. 11; 220,
p.198
AOC Sample - Mesa IV, West Mine Waste Pile M23 and Burial Cell 70b
M23-
XS54-
01-
061118
0-3"
Waste
rock
sand
1806312-1
6/11/18
Uranium
(mg/kg)
86
0.01
23, p.183;
124, pp.5,
25; 220,
pp.251,
252
M23-
XS54-
01-
061118
0-3"
Waste
rock
sand
1806311-1
6/11/18
Radium-
226 (pCi/g)
76.2 M3
NA
23, p.183;
124, pp.9,
38; 220,
pp.247,
248
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC (Ref. 124, p. 38).
Number by which this AOC is to be identified: 25
Name of AOC: Mesa IV 1/4 Mine Waste Pile CO-10_NNWP01
AOC Type: Pile
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Location and description of AOC (with reference to a map of the area): Figure 10 and Figure 11
AOC 25 comprises one waste pile: Mesa IV 1/4 Mine Waste Pile CO-10_NNWP01. This waste pile is in the
southeast portion of the mine area with scattered waste rock extending downslope to the east into the inaccessible
area of the mine. The mine area is located on 20- to 3 5-degree slopes (Ref. 82, p7). The waste generated is a result
of mine operations in ore bodies in the Salt Wash Member of the Lower Morrison Formation. Surficial
contamination documented in the AOC sample results below shows that the waste pile does not have a continuous
cover of 2 feet or greater (Ref. 223, p.20).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 79, p.5; 63, p.65). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
The Morrison Formation BRA was chosen by Cyprus Amax to best represent the background levels for AOC 20
(Refs. 63, p.63; 82, p.8). The highest concentration of each metal analyte from all samples collected from the
Morrison Formation BRA was chosen as the background level (Ref. 63, p.63). The metals analysis was performed
by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Ref. 164, p. 1990). Ra-226
analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy
(Ref. 164, p.2125).
Table 32. Sample Description itiul Analytical Results lor AOC 25
S:i m pic
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a lice
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (Background - Morrison Formation)
79, p.5;
63, p.65
SS-CO-
Bl-008-
1014201
7
0-6"
Unava
ilable
1710392-9
10/14/17
Arsenic
(mg/kg)
2.2
0.2
169,
p.5,1387
ss-co-
Bl-021-
1014201
7
0-6"
Unava
ilable
1710392-23
10/14/17
Uranium
(mg/kg)
1.5
0.01
169,
p.1401
Morrison
Ra-226
0-6"
Unava
ilable
1710392
10/14/17
Radium-
226 (pCi/g)
1.39*
NA
200, p.2;
AOC Samples - Mesa IV 1U
Mine Waste Pile CO-IOJ
\NWP01
SS-10-
NWP01-
002-
10162
0-6"
Waste
rock
sand
1810422-21
10/16/18
Arsenic
(mg/kg)
7.1
0.21
164,
pp.13,
1990
HRS Documentation Record
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Tsihlc 32. Sample Description itiul An;ilv(ii:il Results lor AOC 25
S:i m pic
II)
Siimplc
Depth
Soil
Type"
l.iihoriilorv
S;t in pk- 11)
Dsitc
1 hi/iirdous
Suhsl since
1 l;i/;iriloiis
Siibsl:incc
Cone.
Reporting
Limit2
Reference
SS-ln-
NWP01-
002-
10162
i.i-O"
Was l^-
rock
sand
in 10 IS
L rani inn
(mg/kg)
25
null
164, p.
1990
SS-10-
NWP01-
003-
10162
0-6"
Waste
rock
sand
1810422-5
10/16/18
Radium-
226 (pCi/g)
59.6 M3
NA
164, p.
2125
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC (Ref. 164, p. 2125).
Number by which this AOC is to be identified: 26
Name of AOC: Mesa IV 1/2 Mine and Simpson 181 Waste Pile Ml 9, Burial Cell 86a, and Burial Cell 86b; Mesa
V Mine - 508 Waste Pile M18 and Burial Cell 87a; North Portal Frank No. 1 Mine Waste Pile CO-05_NNWP01,
Waste Pile C0-05_NNWP02, Waste Pile C0-05_NNWP03, and Waste Pile C0-05_NNWP04; East Portal Frank
No. 1 Mine Waste Pile C0-05_NNWP05, Waste Pile C0-05_NNWP06, Waste Pile C0-05_NNWP07, Waste Pile
C0-05_NNWP08, Waste Pile C0-05_NNWP09, Waste Pile CO-05_NNWP10, Waste Pile CO-05_NNWP11,
Waste Pile CO-05_NNWP12, and Waste Pile CO-05_NNWP13; South Portal Frank No. 1 Mine Waste Pile CO-
05_NNWP14, Waste Pile CO-05_NNWP15, Waste Pile CO-05_NNWP16, Waste Pile CO-05_NNWP17, Waste
Pile CO-05 NNWP18, and Waste Pile CO-05_NNWP19; and Frank No. 2 Mine Waste Pile CO-06_NNWP01.
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 10 and Figure 11
AOC 26 comprises 25 waste piles: Mesa IV 1/2 Mine and Simpson 181 Waste Pile M19, Burial Cell 86a, and
Burial Cell 86b; Mesa V Mine - 508 Waste Pile M18 and Burial Cell 87a; North Portal Frank No. 1 Mine Waste
Pile CO-05_NNWP01, Waste Pile C0-05_NNWP02, Waste Pile C0-05_NNWP03, and Waste Pile CO-
05_NNWP04; East Portal Frank No. 1 Mine Waste Pile C0-05_NNWP05, Waste Pile C0-05_NNWP06, Waste
Pile C0-05_NNWP07, Waste Pile C0-05_NNWP08, Waste Pile C0-05_NNWP09, Waste Pile CO-
05_NNWP10, Waste Pile CO-05_NNWP11, Waste Pile CO-05_NNWP12, and Waste Pile CO-05_NNWP13;
South Portal Frank No. 1 Mine Waste Pile CO-05_NNWP14, Waste Pile CO-05_NNWP15, Waste Pile CO-
05_NNWP16, Waste Pile CO-05_NNWP17, Waste Pile CO-05 NNWP18, and Waste Pile CO-05_NNWP19; and
Frank No. 2 Mine Waste Pile CO-06_NNWP01 (Refs. 18, pp.27,30, 31; 19, pp.32,33; 76, pp.6,7,8,41,42,43, 95,
96, 97, 98; 77, pp.4,32).
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Cyprus Amax prepared the RSE report for the waste piles in AOC 26 under a consent decree signed in 2017 (Ref.
199, p. 95). The Cyprus Amax RSE breaks out waste piles into smaller areas than other RSEs, and, thus, this
AOC contains 25 small areas considered to be interconnected waste piles. All waste piles are aggregated into a
single AOC because of their proximity, similar waste type, same AOC type, and similar past operational history.
Mesa IV 1/2 Mine and Simpson 181 is located south of Mesa V Mine - 508. South of Mesa IV 1/2 Mine and
Simpson 181 is the North Portal Frank No. 1 Mine (Ref. 18, p.21). East Portal Frank No. 1 Mine and South Portal
Frank No. 1 Mine are located southeast and south of North Portal Frank No. 1 Mine, respectively (Refs. 19, p.22;
76, pp.41,42,43). Frank No. 2 Mine is located between East Portal Frank No. 1 Mine and South Portal Frank
No. 1 Mine (Ref.76, p.42). All are located along the same ore outcrop on the south side of Mesa V.
Mine waste at Mesa IV 1/2 Mine and Simpson 181 Waste Pile M19 is shallow at approximately 3 feet deep on a
slope greater than 30 degrees in places and is highly erodible. Burial Cell 86b is located northwest of Waste Pile
M19 and vegetated. A tributary of the Cove Wash Middle IB runs along the southern boundary of Burial Cell 86b
and bisects Waste Pile M19 (Ref. 19, pp.32,33,133). Mesa V Mine - 508 Waste Pile M18 is a surficial waste pile
at approximately 4 feet deep on a slope greater than 30 degrees and is highly erodible. A drainage runs directly
through the waste pile boundary and likely flows down to the Cove Wash Middle IB drainage. Burial Cell 87a is
located north and upgradient of Waste Pile M18 (Ref. 18, pp.-30,-31). The waste generated at the mines is a result
of mine operations in ore bodies in the Salt Wash Member of the Lower Morrison Formation (Refs. 18, pp.23,24;
19, pp.24,25). Surficial contamination documented in the AOC sample results below shows that the waste piles do
not have a continuous cover of 2 feet or greater. The workings at Mesa V Mine - 508 extend north, east, and west
of the mine area and connect to Mesa V Mine - 103 (Ref. 18, p.27).
North Portal Frank No. 1 Mine Waste Pile CO-05_NNWP01 is buried, but a clean cover as defined by CERCLA
appears not to have been applied; therefore, the waste pile does not have a continuous cover of 2 feet or greater
(Ref. 76, p. 10). Waste Pile C0-05_NNWP02 is in the northeast portion of North Portal Frank No. 1 Mine and
extends downslope into a wash and steep inaccessible areas of the mine (Ref. 76, p. 10). The Cove Wash Middle
IB drainage runs along the northern portion of North Portal Frank No. 1 Mine and connects with a tributary to the
Cove Wash Middle IB drainage that runs across Mesa IV 1/2 Mine and Simpson 181 (Refs. 19, p.33; 76,
pp. 10,49). Waste Piles C0-05_NNWP03 and C0-05_NNWP04 are noted as reclaimed waste rock piles, but
surficial contamination documented in the AOC sample results below shows that the waste piles do not have a
continuous cover of 2 feet or greater.
East Portal Frank No. 1 Mine Waste Piles C0-05_NNWP05 through CO-05_NNWP10 are in inaccessible areas
of the mine site. These five waste piles are below the main bench of the mine. Waste Piles CO-05_NNWP11, CO-
05_NNWP12, and CO-05_NNWP13 are located along the west end of the main bench (Ref. 76, pp.10,11,50). A
drainage cuts across the mine area and connects to the Cove Wash Middle 1C drainage (Ref. 63, p.85). Surficial
contamination documented in the AOC sample results below shows that the waste piles do not have a continuous
cover of 2 feet or greater.
South Portal Frank No. 1 Mine Waste Piles CO-05_NNWP15, CO-05_NNWP16, and CO-05_NNWP18 are
located below the main bench in the southern portion of the mine area below a steep cliff edge. Waste Piles CO-
05_NNWP14, CO-05_NNWP17, and CO-05_NNWP19 were moved and buried, but surficial contamination
documented in the AOC sample results below shows that the waste piles do not have a continuous cover of 2 feet
or greater (Ref. 76, pp.11,43). A drainage runs across the mine area and connects to the Cove Wash Middle ID
drainage (Ref. 23, p.20).
Frank No. 2 Mine Waste Pile CO-06_NNWP01 is partially accessible with material spilled over a steep cliff.
Surficial contamination documented in the AOC sample results below shows that the waste pile does not have a
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continuous cover of 2 feet or greater. Frank No. 2 Mine and East Portal Frank No. 1 Mine straddle the same Cove
Wash Middle 1C drainage (Ref. 63, p.85).
The waste generated at Mesa IV 1/2 Mine and Simpson 181, Mesa V Mine - 508, North Portal Frank No. 1 Mine,
East Portal Frank No. 1 Mine, South Portal Frank No. 1 Mine, and Frank No. 2 Mine is a result of mine
operations in ore bodies in the Salt Wash Member of the Lower Morrison Formation (Refs. 18, p.24; 19, p.25; 76,
pp.41,42,43; 77, p.22).
All waste samples are surface samples collected from the waste piles but are generally referred to in the RSE
report as soil samples. Observed contamination is established by analytical significance above background levels.
For surface waste samples analyzed for metals, observed contamination is established when the metal
concentration is three times the highest background concentration. Background levels are determined based on the
highest analyte-specific background concentration from the AOC-specific background study area (Refs. 18, p.33;
19, p.35; 43, pp.2001,2104; 63, p.65; 76, p.10; 80, p.5). For Ra-226, observed contamination is established when
the Ra-226 concentration is two standard deviations above the mean site-specific Ra-226 background
concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for this AOC also exceed the upper-limit
range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp. 2,3; 221, p.25; 222, pp. 171-174).
BSA-19 was selected as the most appropriate background location for waste piles M19 and Burial Cell 86b (Ref.
19, p.35; 43, p.2001). BSA-20 was selected as the most appropriate background location for waste piles M18 and
Burial Cell 87a (Ref. 18, p.33; 43, p.2104). The Morrison Formation BSA was the most appropriate BRA for the
remaining waste piles (Ref. 63, p.65; 76, p. 10; 80, pp. 5). The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Refs. 84, pp 2,71,73; 113, pp.59,61;
115, pp.2,25,27; 149, pp.472,1164,2143,2321,2749,2754, 2759, 2762, 2769, 3020, 4325; 162, p.77; 169,
pp. 1120,1387,1401). Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA method
901.1 gamma spectroscopy (Refs. 84, pp. 2,128; 113, p.108; 115, pp.2,51; 149, pp.761,1520,2256,2453,2662,
2894,2896,2901,2904,2912,3658,4473,4494; 162, p.347; 169, p. 1604).
Table 33. Sample Description itiul Analytical Results lor AOC 2ft
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 lazarilous
Su list a nee
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 19)
19, P-35;
43, p.2001
B19-
SS28-01-
052618
0-6"
Silty
sand
1806158-
15
5/26/18
Uranium
(mg/kg)
1
0.01
43, p.6938;
112, pp. 6,
50; 220,
p.174
BSA-19
0-6"
Silty
sand
1806157
5/26/18
Radium-
226 (pCi/g)
1.43*
NA
43, p.6932;
200, p.2;
112, p.10;
220, p. 166
AOC Sample - Mesa IV 1/2
Mine and Simpson 181 Waste Pile M19
M19-
SS36-01-
091818
0-6"
Waste
1809426-
18
9/18/18
Uranium
(mg/kg)
390
0.1
19, p.188;
84,
pp.6,73;
220, p.586
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98
Lukachukai Mountains Mining District
NNN000920223
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Table 33. Sample Description itiul Analytical Results lor AOC 26
S;t in pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/ardous
Substance
1 la/ardous
Substance
Cone.
Reporting
Limit2
Reference
Mly-
SS36-01-
091818
u-o"
Waste
1SU9427-
18
9. 18. IS
Radi um-
226 (pCi/g)
157 M3
-\A
19, p. 1SS,
84,
pp.10,128;
220, p.592
AOC Sample - Mesa IV 1/2
Mine and Simpson 181 Burial Cell 86b
M19-
XS22-
02-
052318
0-3"
Waste
1805632-7
5/23/18
Uranium
(mg/kg)
370
0.1
19, p.178;
115,
pp.5,25;
220, p.158
M19-
XS22-
02-
052318
0-3"
Waste
1805633-8
5/23/18
Radium-
226 (pCi/g)
21.5
(215 J)
NA
19, p.178;
115,
pp.9,51;
220,p. 162
Background Sample (BSA 20)
18, P-33;
43, p.2104
B20-
SS25-01-
052318
0-3"
Sandy
loam
1805628-
30
5/23/18
Arsenic
(mg/kg)
1.6
0.2
43, p.
6945; 114,
pp.6, 79;
220, p. 139
B20-
SS12-01-
052318
0-3"
Sandy
loam
1805628-
15
5/23/18
Uranium
(mg/kg)
0.55
0.01
43, p.
6943; 114,
pp.6, 49;
220, p.138
BSA-20
0-6"
Sandy
loam
1805629
5/23/18
Radium-
226 (pCi/g)
0.81*
NA
43, pp.
6940,
6941; 200,
p.2; 114,
p. 10; 220,
p.141
AOC Sample - Mesa V Mine - 508 Waste Pile M18 and Burial Cel
87a
M18-
SS115-
01-
091418
0-6"
Sand
with
silt
and
gravel
1809349-
12
9/14/18
Arsenic
(mg/kg)
26
0.2
18, p.217;
113,
pp.5,59;
220, p.903
M18-
SS115-
02-
091418
0-6"
Sand
with
silt
and
gravel
1809349-
13
9/14/18
Uranium
(mg/kg)
22
0.0098
18, p.217;
113,
pp.5,61;
220, p. 901
M18-
S115-02-
091418
0-6"
SM
with
gravel
1809351-
13
9/14/18
Radium-
226 (pCi/g)
15.9
NA
18, p.217;
113,
p.9,108;
220, p.507
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99
Lukachukai Mountains Mining District
NNN000920223
-------
Table 33. Sample Description itiul Analytical Results lor AOC 26
S;t in pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/ardous
Su list a nee
1 la/ardous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (Background - Morrison Formation)
76, p. 10;
63, p.65
SS-CO-
Bl-021-
1014201
7
0-6"
Unava
ilable
1710392-
23
10/14/17
Uranium
(mg/kg)
1.5
0.01
169, p.
14,1401
Morrison
Ra-226
0-6"
Unava
ilable
1710392
10/14/17
Radium-
226 (pCi/g)
1.39*
NA
200, p.2;
169, p.14
AOC Sample - North Portal Frank No. 1
Mine Waste Piles CO-05 NNWP01 and CO-05 NN
WP04
SB-05-
NNWPO
1-002-
1.0-1.
12-18"
Waste
1810425-
19
10/12/18
Radium-
226 (pCi/g)
5.82
NA
149,
pp. 13,4494
AOC Sample - North Portal Frank No. 1
Mine Waste Pile CO-05 J
\NWP02
SS-05-
NNWP0
2-001-
10062
0-6"
Waste
1810357-
13
10/6/18
Uranium
(mg/kg)
95
0.0099
149, pp.
13,3020
SS-05-
NNWP0
2-001-
10062
0-6"
Waste
1810357-
13
10/6/18
Radium-
226 (pCi/g)
56 M3
NA
149,
pp.13,3658
AOC Sample - North Portal Frank No. 1
Mine Waste Pile CO-05 J
\NWP03
SB-05-
NNWP0
3-002-
1.0-1.
12-18"
Waste
1810425-
13
10/12/18
Uranium
(mg/kg)
43
0.011
149,
pp. 13,4325
SB-05-
NNWP0
3-002-
1.0-1.
12-18"
Waste
1810425-
13DUP
10/12/18
Radium-
226 (pCi/g)
13.4
NA
149,
pp. 13,4473
AOC Sample - East Portal Frank No. 1IV
line Waste Pile CO-05_N
NWP05
SB-05-
NNWP0
5-001-
1.0-1.
12-18"
Waste
1809446-
15
9/17/18
Uranium
(mg/kg)
16
0.01
149,
pp. 13,2762
SB-05-
NNWP0
5-001-
1.0-1.
12-18"
Waste
1809446-
15
9/17/18
Radium-
226 (pCi/g)
12.5
NA
149,
pp. 13,2904
HRS Documentation Record
100
Lukachukai Mountains Mining District
NNN000920223
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Table 33. Sample Description itiul Analytical Results lor AOC 26
S;t in pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a nee
1 la/arilous
Suhstance
Cone.
Reporting
Limit2
Re Terence
AOC Sample - East Portal F
05 NNWP09, and CO-05 NI
rank No. 1IV
VWP10
ine Waste Piles CO-05_]>
JNWP06, CO-05 NNWP08, CO-
SB-05-
NNWPO
6-001-
1.0-1.
12-18"
Waste
1809446-2
9/17/18
Uranium
(mg/kg)
14
0.01
149,
pp. 13,2749
SB-05-
NNWP0
6-002-
1.0-1.
12-18"
Waste
1809446-5
9/17/18
Radium-
226 (pCi/g)
10.1
NA
149,
pp. 13,2894
AOC Sample - East Portal Frank No. 1IV
ine Waste Piles CO-05_]>
JNWP11 and CO-05 NNWP07
SB-05-
NNWP1
1-001-
1.0-1.
12-18"
Waste
1809446-
12
9/17/18
Uranium
(mg/kg)
15
0.01
149,
pp. 13,2759
SB-05-
NNWP1
1-001-
1.0-1.
12-18"
Waste
1809446-
12
9/17/18
Radium-
226 (pCi/g)
10.1
NA
149,
pp. 13,2901
AOC Sample - East Portal Frank No. 1IV
line Waste Pile CO-05_N
NWP12
SS-05-
NNWP1
2-001-
09172
0-6"
Waste
1809446-
22
9/17/18
Uranium
(mg/kg)
14
0.0087
149,
pp. 13,2769
SS-05-
NNWP1
2-001-
09172
0-6"
Waste
1809446-
22
9/17/18
Radium-
226 (pCi/g)
12.3
NA
149,
pp.13,2912
AOC Sample - East Portal Frank No. 1IV
line Waste Pile CO-05_N
NWP13
SS-05-
NNWP1
3-001-
09172
0-6"
Waste
1809446-7
9/17/18
Uranium
(mg/kg)
9,3
0.0099
149, pp.
13,2754
SS-05-
NNWP1
3-001-
09172
0-6"
Waste
1809446-7
9/17/18
Radium-
226 (pCi/g)
7.5
NA
149,
pp. 13,2896
AOC Sample - South Portal Frank No. 1
Mine Waste Pile CO-05_
NTNWP14
SB-05-
NNWP1
4-001-
1.0-1.
12-18"
Waste
1809343-
17
9/14/18
Radium-
226 (pCi/g)
5.68
NA
149, pp.
13,2662
AOC Sample - South Portal Frank No. 1
Mine Waste Pile CO-05_
NTNWP15
HRS Documentation Record
101
Lukachukai Mountains Mining District
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Table 33. Sample Description itiul Analytical Results lor AOC 26
S;t in pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/ardous
Substance
1 la/ardous
Substance
Cone.
Reporting
Limit2
Reference
SS-U5-
MS-004-
1024201
7
u-o"
Waste
171U0U0-5
lU. 24.17
L ram tun
(mg/kg)
120
U.U95
149, pp.
13, 472
SS-05-
MS-004-
1024201
7
0-6"
Waste
1710606-5
10/24/17
Radium-
226 (pCi/g)
91
NA
149, pp.
13,761
AOC Sample - South Portal Frank No. 1
Mine Waste Pile CO-05 NNWP16
SB-05-
NNWP1
6-001-
1.0-1.
12-18"
Waste
1809339-2
9/11/18
Uranium
(mg/kg)
470
0.099
149, pp.
13,1164
SB-05-
NNWP1
6-001-
1.0-1.
12-18"
Waste
1809339-2
9/11/18
Radium-
226 (pCi/g)
176
NA
149, pp.
13,1520
AOC Sample - South Portal Frank No. 1
Mine Waste Pile CO-05_
VNWP18
SB-05-
NNWP1
8-003-
1.0-1.
12-18"
Waste
1809342-8
9/13/18
Uranium
(mg/kg)
630
0.091
149, pp.
13,2321
SS-05-
NNWP1
8-03-
091320
0-6"
Waste
1809342-7
9/13/18
Radium-
226 (pCi/g)
125
NA
149,
pp. 13,2453
AOC Sample - South Portal Frank No. 1
Mine Waste Piles CO-05 NNWP19 and CO-05 NN
WP17
SB-05-
NNWP1
9-002-
1.0-1.
12-18"
Waste
1809340-
14
9/12/18
Uranium
(mg/kg)
31
0.0099
149, pp.
13,2143
SB-05-
NNWP1
9-002-
1.0-1.
12-18"
Waste
1809340-
14
9/12/18
Radium-
226 (pCi/g)
10.3
NA
149, pp.
13,2256
Background Sample (Background -Morrison Formation)
80, p.5; 63,
p.65
SS-CO-
Bl-021-
1014201
7
0-6"
Unava
ilable
1710392-
23
10/14/17
Uranium
(mg/kg)
1.5
0.01
169, pp.
13,1401
Morrison
Ra-226
0-6"
Unava
ilable
1710392
10/14/17
Radium-
226 (pCi/g)
1.39*
NA
200, p.2;
169, p.13
AOC Sample - Frank No. 2
Mine Waste Pile CO-06J
VNWP01
HRS Documentation Record
102
Lukachukai Mountains Mining District
NNN000920223
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Tsthle 33. Sitniple Description itiul Atiitlvliciil Results lor AOC 2ft
S;t in pie
II)
S;t m pie
Depth
Soil
Type1
l.iihomtorv
Sit 111 pic 11)
Ditte
1 lit/iirdoiis
Sit list it nee
11 it/:t rtl otts
Siihstitnce
Cone.
Reporting
Limit2
Re Terence
SS-UO-
MS-003-
1025201
7
U-0"
\\ as it-
171U59U-3
lU. 24.17
I rani tun
(mg/kg)
30U
U.l
162, pp.
14, 77
SS-06-
MS-003-
1025201
7
0-6"
Waste
1710590-
3DUP
10/24/17
Radium-
226 (pCi/g)
305 M3
NA
162,
pp. 12,347
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
E This flag identifies compounds whose concentration exceeds the upper level of the calibration range.
J The analyte was detected at the reported concentration; the quantitation is an estimate. As a waste sample,
the concentration of this qualified data is reported with an adjustment (Ref. 48, p.7, 8).
LT Result is less than the requested minimum detectable concentration (MDC) but greater than the sample-
specific MDC.
M3 The requested MDC was not met, but the reported activity is greater than the reported MDC.
Number by which this AOC is to be identified: 27
Name of AOC: NA-0316 Waste Pile CO-11_NNWP01, Waste Pile CO-11_NNWP02, and Waste Pile CO-
11_NNWP03
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 10 and Figure 11
AOC 27 comprises three waste piles: NA-0316 Waste Pile CO-11_NNWP01, Waste Pile CO-11_NNWP02, and
Waste Pile CO-11-NNWP03. These three mine features are aggregated together into a single AOC because of
their proximity, similar waste type, same AOC type, impacts on the same targets, and similar past operational
history. Waste Pile CO-11_NNWP01 and Waste Pile CO-11_NNWP02 are located along the central and south
edge of the main bench, respectively, and consist of scattered waste below the cliff edge and main bench.
According to NAML, Waste Pile CO-11_NNWP03 is in the northwestern portion of the mine area above Waste
Piles CO-11_NNWP01 and CO-11_NNWP02 (Ref. 78, pp.4,24). A drainage runs across the mine area and
connects to the Cove Wash Middle IE drainage (Ref. 23, p.20). The waste generated is a result of mine operations
in ore bodies in the Salt Wash Member of the Lower Morrison Formation. Surficial contamination documented in
the AOC sample results below shows that the waste piles do not have a continuous cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
HRS Documentation Record
103
Lukachukai Mountains Mining District
NNN000920223
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as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background reference area (Refs. 78, p.6; 63, p.65). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
The Morrison Formation BRA was chosen by Cyprus Amax to best represent the background levels for AOC 20
(Refs. 63, p.63; 82, p.8). The highest concentration of each metal analyte from all samples collected from the
Morrison Formation BRA was chosen as the background level (Ref. 63, p.63). The metals analysis was performed
by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Ref. 163, pp.708,940,948).
Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Ref. 163, pp.845,1089,1098).
Table 34. Sample Description itiul Analytical Results lor AOC 27
Nil m pic
Sample
Soil
Laboratory
Date
1 lazarilous
1 la/arilous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Su list a nee
Substance
Cone.
Limit2
Background Sample (Background - Morrison Formation)
78, p.6; 63,
p.65
SS-CO-
0-6"
Unava
1710392-
10/14/17
Uranium
1.5
0.01
169, pp.
Bl-021-
10142017
ilable
23
(mg/kg)
13,1401
Morrison
0-6"
Unava
1710392
10/14/17
Radium-226
1.388*
NA
200, p. 2;
Ra-226
ilable
(pCi/g)
169, p.13
AOC Sample - NA-0316 Waste Pile CO-11_NNWP01
SS-11-
0-6"
Waste
1810419-
10/13/18
Uranium
9.9
0.011
163, pp.
NNWP0
17
(mg/kg)
13, 948
1-001-
10132
SS-11-
0-6"
Waste
1810419-
10/13/18
Radium-226
7.7
NA
163, pp.
NNWP0
17
(pCi/g)
13, 1098
1-001-
10132
AOC Sample - NA-0316 Waste Pile CO-11_NNWP02
SS-11-
0-6"
Waste
1810419-9
10/13/18
Uranium
150
0.11
163, pp.
NNWP0
(mg/kg)
13, 940
2-004-
10132
SS-11-
0-6"
Waste
1810419-9
10/13/18
Radium-226
72
NA
163, pp.
NNWP0
(pCi/g)
13,1089
2-004-
10132
AOC Sample - NA-0316 Waste Pile CO-11_NNWP03
SS-11-
0-6"
Waste
1809441-
9/17/18
Uranium
7.5
0.0093
163, pp.
NNWP0
12
(mg/kg)
13, 708
HRS Documentation Record
104
Lukachukai Mountains Mining District
NNN000920223
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Tsihlc 34. Siimplc Description itiul \n;ilv(ic:il Results lor AOC 27
S:i m pic
II)
Siimplc
Depth
Soil
Type"
l.iihoriilorv
Siimplc 11)
Diitc
1 lit/itrdous
Suhsliincc
1 l;i/;irilous
Suhsl:incc
Cone.
Reporting
Limit2
Reference
3-003-
09172
SS-11-
NNWP0
3-001-
09172
0-6"
Waste
1809441-6
9/17/18
Radium-226
(pCi/g)
8.2
NA
163,
pp. 13,845
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 28
Name of AOC: Cov087 Waste Pile
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 10 and Figure 11
AOC 28 comprises one waste pile: Cov087 Waste Pile. The waste generated is a result of mine operations in ore
bodies in the Salt Wash Member of the Lower Morrison Formation. Surficial contamination documented in the
AOC sample results below shows that the waste pile does not have a continuous cover of 2 feet or greater (Ref.
53, p.11).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 78, p.6; 63, p.65).
BSA-20 was selected as the most appropriate background location for AOC 28 because it is within the same
geologic unit (Morrison Formation) and it hosts soil of the same type (Refs. 18, p. 25; 76, p. 49; 43, pp.
2084,2087). The metals analysis was performed by ALS Environmental Laboratories using USEPA method SW-
846 6020A ICP-MS (Ref. 163, pp.708,940,948). Ra-226 analysis was performed by ALS Environmental
Laboratories using USEPA method 901.1 gamma spectroscopy (Ref. 163, pp.845,1089,1098).
HRS Documentation Record
105
Lukachukai Mountains Mining District
NNN000920223
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Table 35. Sample Description and Analytical Results lor AOC 2S
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/ardous
Substance
1 la/ardous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 20)
18, P-33;
43, p.2104
B20-
SS25-01-
052318
0-3"
Sandy
loam
1805628-
30
5/23/18
Arsenic
(mg/kg)
1.6
0.2
43,
p.6945;
114,
pp.6,79;
220, p.
139
B20-
SS25-01-
052318
0-3"
Sandy
loam
1805628-
30
5/23/18
Lead
(mg/kg)
5.4
0.2
43,
p.6945;
114,
pp.6,79;
220, p.
139
B20-
SS25-01-
052318
0-3"
Sandy
loam
1805628-
30
5/23/18
Uranium
(mg/kg)
0.29
0.01
43,
p.6945;
114,
pp.6,79;
220, p.
139
AOC Sample - Cov087 Waste Pile
M18-
XS161-
01-
052518
0-3"
Silty
sand
with
gravel
1805632-6
5/25/18
Arsenic
(mg/kg)
5.6
0.2
115,
pp.23,47;
220, p.
160
M18-
XS161-
01-
052518
0-3"
Silty
sand
with
gravel
1805632-6
5/25/18
Lead
(mg/kg)
21
0.2
115,
pp.23, 47;
220, p.
160
M18-
XS161-
01-
052518
0-3"
Silty
sand
with
gravel
1805632-6
5/25/18
Uranium
(mg/kg)
300
0.098
115,
pp.23;
220, p.
160
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
Description of Areas of Concern - Mesa IV
Given the interconnected nature of the ore bodies, similar mining processes, similar time frames of operation,
and general geology of the LMMD site, the possible mining-related sources listed below may be releasing
hazardous substances to the Cove Wash drainages or exposing human or terrestrial sensitive environment targets.
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106
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NNN000920223
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The other possible sources and AOCs will be evaluated during further investigation of this area.
T:i hie 36. Mesa IV Other A rest of Concern
Other Area of Concern
Description (Reference)
Cov068
Cov068 is northwest of Mesa IV, Mine No. 3. The mine-related area is within the
Lower Morrison Formation (Ref. 22, p.23). Inventory of Cov068 lists two waste
piles, one rimstrip, and one pit. The two waste piles were documented in the
southern portion of the mine area and are approximately 80 feet apart (Ref. 47,
pp.4,10,11). Weston conducted a gamma scan in 2010, and the highest gamma
measurement was 353,622 cpm, which is significantly higher than the highest
background gamma level measurement of 9,805 cpm (Ref. 47, pp.3,10,11).
Areas of Observed Contamination 29 to 32 - Mesa V and Mesa VI
The Mesa V and Mesa VI area includes four AOCs located at seven mines and mine-related areas.
Table 37. Mesa V and Mesa VI AOCs
AOC
AOC
Mine Claim Names
RSE Waste Pile Names
No.
Type
29
Pile
Mesa V Mine - 103;
Mesa V Adit;
NA-0344B; Mesa V
Incline
Waste Piles M15A, M15B, M16A, M16B, and M17; Burial
Cells 91, 92, 93, and 344B-2
30
Pile
Mesa V & Mesa VI
Waste Piles M13A and MOB
31
Pile
Mesa V & Mesa VI
CO-04 NNWP01
32
Pile
Mesa V & Mesa VI
Waste Pile M14
The Mesa V and Mesa VI area includes six mines developed and operated in the 1950s and 1960s by F.A. Sitton,
the Navajo Uranium Mining Company, Kerr-McGee (a predecessor of Tronox), and VCA. In addition, one mine
was developed in the 1950s and 1960s by the Climax Uranium Company (a predecessor of Cyprus Amax) (Refs.
13, p.26; 14, p.25; 15, p.25; 16, p.26; 17, p.25; 75, p.3). Four additional mine-related areas are also found within
the Mesa V and Mesa VI area (Refs. 13, p.26; 14, p.25; 15, p.25; 16, p.26,31; 17, p.25,31). Operations included
underground mining that tapped paleochannels in the Salt Wash Member of the Lower Morrison Formation that
are rich in uranium and vanadium. Underground mine workings exist throughout the Mesa V and Mesa VI area.
Waste piles consist of overburden or lower grade protore discarded near or downslope of portals (Refs. 13,
pp.24,27,31; 14, pp.21,31,32; 15, pp.21,30,31; 16, pp.22,32; 17, pp.21,32; 75, pp.23,26).
Number by which this AOC is to be identified: 29
Name of AOC: Mesa V Incline Waste Pile M15A and Waste Pile M15B; Mesa V Adit Waste Pile M 16A, Waste
Pile M16B, Burial Cell 91, Burial Cell 92, and Burial Cell 93; Mesa V Mine - 103 Waste Pile Ml7; NA-0344B
Burial Cell 344B-2
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 12
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Lukachukai Mountains Mining District
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AOC 29 comprises nine waste piles: Mesa V Incline Waste Pile M15A and Waste Pile M15B; Mesa V Adit
Waste Pile M16A, Waste Pile M16B, Burial Cell 91, Burial Cell 92, and Burial Cell 93; Mesa V Mine - 103
Waste Pile M17; and NA-0344B Burial Cell 344B-2. These nine mine features are aggregated together into a
single AOC because of their proximity, similar waste type, same AOC type, impacts on the same targets, and
similar past operational history. Waste Pile M15A and Waste Pile M15B are located in the northern portion and
southern portion of Mesa V Incline, respectively. Offsite migration of waste material from Mesa V Incline into
the Cove Wash Middle 1A drainage was confirmed; however, the amount of material is unknown. A drainage was
mapped on Waste Pile M15A (Ref. 15, pp.30,31). Waste Pile M16A is located below a cliff in the southern
portion of Mesa V Adit. Waste Pile M16A has extreme slopes, exposed ore, and large boulders, and waste from
the pile slumps against the cliff wall to the north. Waste Pile M16B is in the northern portion of Mesa V Adit
above the cliff area. Two drainages run directly through Waste Pile M16B into the Cove Wash Middle 1A
drainage. Waste Pile M16B has an approximate depth of 5 feet and is highly erodible with offsite migration
documented (Ref. 16, pp.31,32). Waste Pile M17 is 20 feet deep on a slope greater than 30 degrees and is
considered highly erodible. Offsite migration of Waste Pile M17 into the Cove Wash Middle 1A drainage has
been documented (Ref. 17, pp.31,32). Within Waste Pile M16B, Burial Cell 91 is located in the northwestern
portion, Burial Cell 92 is located in the north-central portion, and Burial Cell 93 is located in the northeastern
portion. All three burial cells are covered with material containing elevated radionuclide concentrations. No
drainages were mapped within the burial cells, and the material appeared to be stable. Offsite migration of
contaminated material from the burial cells is likely (Ref. 16, pp.31,133). Burial Cell 344B-2 is located north of
Mesa V Incline. While no mining activities occurred at NA-0344B, Burial Cell 344B-2 was constructed between
2003 and 2004 to include overburden, mine debris, and waste rock from mining that occurred at Mesa V Incline,
Mesa V Adit, Mesa V Mine - 103, and Mesa V Mine - 508. The burial cell was covered with 1.5 feet of soil.
Because of the relatively flat topography at NA-0344B, the potential for offsite migration is not likely; however,
offsite migration would flow through Mesa V Incline and Mesa V Adit before reaching the Cove Wash Middle
1A drainage (Ref. 42, pp.26,29,31,129). The waste generated is a result of mine operations in ore bodies within
the Salt Wash Member of the Lower Morrison Formation (Refs. 15, p.23; 16, p.24; 17, p.23). Surficial
contamination documented in the AOC sample results below shows that the waste piles do not have a continuous
cover of 2 feet or greater. The workings for Mesa V Mine - 103 extend west to Mesa V Mine - 508 (Ref. 17,
p.27).
All waste samples are surface samples collected from the waste piles but are generally referred to in the RSE
report as soil samples. Observed contamination is established by analytical significance above background levels.
For surface waste samples analyzed for metals, observed contamination is established when the metal
concentration is three times the highest background concentration. Background levels are determined based on the
highest analyte-specific background concentration from the AOC-specific background study area (Refs. 15, p.33;
16, p.34; 17, p.34; 42, p.33; 43, pp.2001,2207,2309). For Ra-226, observed contamination is established when the
Ra-226 concentration is two standard deviations above the mean site-specific Ra-226 background concentration
(Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for this AOC also exceed the upper-limit range of regional
background of 2.23 pCi/g. (Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174).
BSA-21 was selected as the most appropriate background location for seven of the nine waste piles (Ml 5 A,
M15B, M16A, M16B, Burial Cell 91, Burial Cell 92, and Burial Cell 93) because it is within the same geologic
unit (Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the waste piles (Refs. 15, pp.
22,24,26; 43, p. 2187,2189). BSA-19 was selected as the most appropriate background location for waste piles
M17 because it is within the same geologic unit (undifferentiated Summerville and Entrada Formations), it hosts
soil of the same type, and it's the closest BSA to the M17 waste pile (Refs. 17, pp. 20,22,33; 43, p. 1981). BSA-
22 was selected as the most appropriate background location for waste piles Burial Cell 344B-2 because it is
within the same geologic unit (Morrison Formation) and it hosts soil of the same type (Refs. 17, pp. 20,22,33; 43,
pp. 2289,2291). The metals analysis was performed by ALS Environmental Laboratories using USEPA method
HRS Documentation Record
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NNN000920223
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SW-846 6020A ICP-MS. Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA
method 901.1 gamma spectroscopy (Refs. 108, pp.2,35,57,63,71,79; 109, pp.2,92; 110, pp.2,51,94; 111,
pp.2,35,37,94,102).
Table 38. Sample Description itiul Analytical Results
lor AOC'2')
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
Background Samp
es (BSA 21)
15, P-33;
16, p.34;
43, p.2207
B21-
0-6"
Silty
1806627-
6/21/18
Uranium
9.5
0.0096
43, pp.
SS07-
sand
11
(mg/kg)
6948,6949;
01-
106, p.41;
062118
220, p.277
BSA-21
0-6"
Silty
sand
1806626
6/21/18
Radium-226
(pCi/g)
5.46*
NA
43, pp.
6948,
6949; 200,
pp. 1, 2;
106, p. 11;
220, p.267
AOC Sample - Mesa V Inc
ine Waste Pile M15A
M15-
0-3"
Waste
1805592-1
5/21/18
Radium-226
63.5 M3
NA
15, p.183;
XS22-
rock
(pCi/g)
108, pp.
01-
sand
10, 63;
052118
220, p. 121
AOC Sample - Mesa V Inc
ine Waste Pile M15B
M15-
0-3"
Waste
1805592-5
5/21/18
Radium-226
44.8 M3
NA
15, p.176;
XS73-
rock
(pCi/g)
108,
01-
sand
pp.10,71;
052118
220, p. 119
AOC Samples - Mesa V At
it Waste Pile
M16A and
Burial Cell 91
M16-
0-6"
Waste
1809298-3
9/13/18
Uranium
52
0.0095
16, p. 217;
SS193-
rock
(mg/kg)
109, pp. 6,
01-
sand
92; 220, p.
091318
908
M16-
0-3"
Waste
1806222-4
5/26/18
Radium-226
39.7
NA
16, p.207;
XS191-
rock
(pCi/g)
111, pp.12,
01-
sand
94; 220,
052618
p.221
AOC Samples - Mesa V At
it Waste Pile
M16B
M16-
0-3"
Waste
1805589-8
5/21/18
Uranium
130
0.1
16, p.189;
XS128-
rock
(mg/kg)
108, pp. 5,
01-
sand
35; 220, p.
052118
107
M16-
0-3"
Waste
1805592-9
5/21/18
Radium-226
65.3
NA
16, p.188;
XS166-
rock
sand
(pCi/g)
108, pp.10,
HRS Documentation Record
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Lukachukai Mountains Mining District
NNN000920223
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Table 38. Sample Description itiul Analytical Results
lor AOC'29
Sample
Sample
Soil
Laboratory
Date
1 la/ardous
1 la/ardous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
Ol-
79; 220,
052118
p.119
AOC Sample - Mesa V Adit Burial Cell 92 and Burial Cell 93
M16-
0-6"
Sandy
1809365-9
9/14/18
Uranium
62
0.0096
16, p.221;
SS47-
gravel
(mg/kg)
110, pp.5,
01-
51; 220, p.
091418
913
M16-
0-6"
Waste
1809366-9
9/14/18
Radium-226
76.7 M3
NA
16, p.221;
SS47-
rock
(pCi/g)
110, pp.13,
01-
sand
94; 220,
091418
p.551
Background Samp
es (BSA 19)
17, P-34;
43, p.2001
B19-
0-6"
Sandy
1806158-5
5/26/18
Arsenic
2.4
0.2
43, p.6932;
SS18-
loam
(mg/kg)
112, pp.6,
01-
30; 220, p.
052618
177
B19-
0-6"
Sandy
1806158-
5/26/18
Uranium
1
0.01
43, p.6932;
SS28-
loam
15
(mg/kg)
112, pp.6,
01-
50; 220,
052618
p.174
BSA-19
0-6"
Sandy
loam
1806157
5/26/18
Radium-226
(pCi/g)
1.43*
NA
43, p.6932;
200, p. 1;
112, p.11;
220, p. 166
AOC Samples - Mesa V Mine - 103 Waste Pile M17
M17-
0-3"
Waste
1806235-7
5/26/18
Arsenic
10
0.2
17, p.194;
XS83-
rock
(mg/kg)
111, pp.6,
01-
sand
35; 220, p.
052618
238
M17-
0-3"
Waste
1806235-8
5/26/18
Uranium
310
0.098
17, p.194;
XS83-
02-
rock
sand
(mg/kg)
111, pp.6,
37; 220,
052618
p.235
M17-
0-3"
Waste
1806222-8
5/26/18
Radium-226
168 M3
NA
17, p.194;
XS83-
02-
rock
sand
(pCi/g)
111, pp.12,
102; 220,
052618
p.221
Background Samp
e (BSA 22)
42, p.33;
43, p.2309
B22-
0-6"
Fine
1805626-7
5/24/18
Uranium
1.3
0.01
43, pp.
SS04-
sand
(mg/kg)
6959,6960;
01-
107, pp.6,
052418
33; 220,
HRS Documentation Record
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Table 38. Sample Description itiul Analytical Results lor AOC 2()
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
pp.124,
133
AOC Sample - NA-0344BI
iurial Cell 344B-2
T23-
XS23-
01-
052118
0-3"
Waste
rock
sand
1805589-
19
5/21/18
Uranium
(mg/kg)
17
0.0099
42, p. 159;
108, pp.5,
57; 220, p.
107
NA
M3
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC.
Number by which this AOC is to be identified: 30
Name of AOC: Mesa VI Mine Waste Pile M13A and Waste Pile M13B
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 12
AOC 30 comprises two waste piles: Mesa VI Mine Waste Pile M13A and Waste Pile M13B. Both waste piles are
aggregated into a single AOC because of their proximity, similar waste type, same AOC type, impacts on the
same targets, and similar past operational history. Waste Pile M13A is in the eastern portion of the mine area. The
lower portion of this waste pile is situated against a sandstone cliff and expands across the Cove Wash North
drainage into the Mesa V New Lease area. Multiple drainages were mapped on Waste Pile M13A. A total average
depth of 15 feet was estimated at Waste Pile M13A. Waste Pile M13B is in the western portion of the mine area.
NA-0319 is next to Waste Pile M13B. The waste generated is a result of mine operations in ore bodies within the
Salt Wash Member of the Lower Morrison Formation. Waste at the mine will migrate downhill into the Cove
Wash North drainage. Surficial contamination documented in the AOC sample results below shows that the waste
piles do not have a continuous cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 13, p. 34; 43, p.2412).
For Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations
HRS Documentation Record
111
Lukachukai Mountains Mining District
NNN000920223
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above the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226
results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116;
200, pp. 2,3; 221, p.25; 222, pp.171-174).
BSA-23 was selected as the most appropriate background location for AOC 30 because it is within the same
geologic unit (Carmel Formation) and it hosts soil of the same type (Refs. 13, pp. 23,25,33; 43, p. 2392). The
metals analysis was performed by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-
MS. Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Ref. 103, pp.2,63,71,110,118).
Table 39. Sample Description
and Analytical Results lor AOC 30
Sample
Sample
Soil
Laboratory
Date
1 lazarilous
1 la/arilous
Reporting
Reference
II)
Depth
Type"
Sample 11)
Su list a nee
Substance
Cone.
Limit2
Background Sample (BSA 23)
13, p.34;
43, p.2412
B23-
0-6"
Sandy
1806236-19
6/6/18
Arsenic
27
0.2
43, p.6973;
SS15-01-
silt
(mg/kg)
85, pp. 6,
060618
57; 220, p.
244
B23-
0-6"
Clayey
1806236-29
6/6/18
Uranium
5.9
0.011
43, p.6974;
SS25-01-
sand
(mg/kg)
85, pp.6,
060618
77; 220,
p.245
BSA-23
0-6"
Silty
sand
1806221
6/6/18
Radium-
226 (pCi/g)
4.51*
NA
43, p.6970;
200. p.l;
85, p.10;
220, p.215
AOC Sample - Mesa VI Mine Waste Pile M13A
M13-
0-6"
Waste
1809355-19
9/15/18
Uranium
710
0.097
13, p. 203;
SS59-01-
091518
rock
sand
(mg/kg)
103, pp. 6,
71; 220, p.
917
M13-
0-6"
Waste
1809356-19
9/15/18
Radium-
367 M3
NA
13, p.203;
SS59-01-
rock
226 (pCi/g)
103, pp.10,
091518
sand
118; 220,
p.525
AOC Sample - Mesa VI Mine Waste Pile M13B
M13-
0-6"
Waste
1809355-15
9/15/18
Arsenic
190
0.19
13, p.205;
SS210-
rock
(mg/kg)
103, pp. 6,
01-
sand
63; 220, p.
091518
917
M13-
0-6"
Waste
1809355-15
9/15/18
Uranium
150
0.094
13, p.205;
SS210-
rock
(mg/kg)
103, pp.6,
01-
sand
63; 220,
091518
p.917
HRS Documentation Record
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Tsihle 39. Siimple Description itiul An;ilv(ii:il Results lor AOC 30
Siimple
II)
Siimple
Depth
Soil
Type1
l.iihoriilorv
S;t in pk- 11)
Diite
1 lii/iirdous
Suhsl since
1 l;i/;irdous
Suhsl:ince
Cone.
Reporting
Limit2
Reference
M13-
SS210-
01-
091518
i.i-O"
Was l^-
rock
sand
1XIW35&-15
y. 15 IS
Radium -
226 (pCi/g)
64.1
\A
13, p.:<>5,
103, pp.10,
110; 220,
p.527
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC.
Number by which this AOC is to be identified: 31
Name of AOC: Cato No. 2 Waste Pile CO-04_NNWP01
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 12
AOC 31 comprises one waste pile: Cato No. 2 Waste Pile CO-04_NNWP01. This waste pile consists of material
removed from the portal and pushed into an ore chute carved into the rock cliff and dropped to the bench below.
This bench was likely built up over time from overburden and waste rock. The mine area is located on 20- to
35-degree slopes with a larger sheer cliff band through the center. The mine area benches are graded relatively
flat. The lower portion of the mine area is accessed through NA-0319 (Ref. 75, pp. 6,7). The waste generated is a
result of mine operations in ore bodies within the Salt Wash Member of the Lower Morrison Formation. Waste at
the mine will migrate downhill into the Cove Wash North drainage. Surficial contamination documented in the
AOC sample results below shows that the waste pile does not have a continuous cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the BRA (Ref. 75, pp.7,8). For Ra-226, observed contamination is
established when the Ra-226 concentration is two standard deviations above the mean site-specific Ra-226
background concentration (Refs. 1, pp.14,116; 200, pp. 1-2). All Ra-226 results forthis AOC also exceed the
upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-
174).
The Morrison Formation BRA was chosen by Cyprus Amax to best represent the background levels for AOC 31
(Refs. 63, p.63; 82, p.8). The highest concentration of each metal analyte from all samples collected from the
HRS Documentation Record
113
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Morrison Formation BRA was chosen as the background level (Refs. 1, p. 14, p. 116; 82, p.6; 63, pp.63,65). The
metals analysis was performed by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-
MS. Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Ref. 140, pp.1178,1181,1304).
Table 40. Sample Description iincl Analytical Results lor AOC 31
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a nee
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Samples (Background - No.
Morrison)
75, p.6
SS-CO-
Bl-021-
1014201
7
0-6"
1710392-
23
10/14/17
Uranium
(mg/kg)
1.5
0.01
169, pp. 13,
1401
Morrison
Ra-226
0-6"
1710392
10/14/17
Radium-
226 (pCi/g)
1.388*
NA
200, p.2;
169, p.13;
218, p.14
AOC Sample - Cato No. 2 Waste Pile CO-04_NNWP01
SS-04-
NNWP0
1-002-
09202
0-6"
Waste
1809484-4
9/20/18
Uranium
(mg/kg)
170
0.094
140, pp.
1145,1181
SS-04-
NNWP0
1-002-
09202
0-6"
Waste
1809484-4
9/20/18
Radium-
226 (pCi/g)
67.4
NA
140, pp.
1145, 1304
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 32
Name of AOC: Frank Jr. Mine Waste Pile M14
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 12
AOC 32 comprises one waste pile: Frank Jr. Mine Waste Pile M14. This waste pile takes up most of the surface
area at Frank Jr. Mine. The waste pile slopes steeply toward the Cove Wash North drainage and is eroding into
the drainage. Offsite migration of waste material from Frank Jr. Mine was confirmed. The waste generated is a
result of mine operations in ore bodies within the Salt Wash Member of the Lower Morrison Formation. Surficial
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contamination documented in the AOC sample results below shows that the waste pile does not have a continuous
cover of 2 feet or greater (Ref. 223, p.20). The workings for Frank Jr. Mine extend south toward NA-0344B,
which is a burial cell that was constructed between 2003 and 2004 (Refs. 14, p.27; 42, p.26).
All waste samples are surface samples collected from the waste pile but are generally referred to in the RSE report
as soil samples. Observed contamination is established by analytical significance above background levels. For
surface waste samples analyzed for metals, observed contamination is established when the metal concentration is
three times the highest background concentration. Background levels are determined based on the highest analyte-
specific background concentration from the AOC-specific background study area (Refs. 14, p.34; 43, p. 1898). For
Ra-226, observed contamination is established when the Ra-226 concentration is two standard deviations above
the mean site-specific Ra-226 background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for
this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp.
2,3; 221, p.25; 222, pp.171-174).
BSA-18 was selected as the most appropriate background location for AOC 32 because it is within the same
geologic unit (Carmel Formation) and it hosts soil of the same type (Refs. 14, pp. 23,33; 43, p. 1878). The metals
analysis was performed by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-MS.
Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Refs. 84, pp.2,55,108; 115, pp.2,13,15).
Table 41. Sample Description itiul Analytical Results lor AOC 32
Sample
Sample
Soil
Laboratory
Date
1 lazarilous
1 la/arilous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Su list a nee
Substance
Cone.
Limit2
Background Sample (BSA 18)
14, P-34;
43, p.1898
B18-
0-6"
Silty
1805630-35
5/25/18
Arsenic
3.6
0.22
43, pp.
SS30-01-
sand
(mg/kg)
6924,
052518
6925; 104,
pp.6,90;
220, p. 146
B18-
0-6"
Silty
1805630-30
5/25/18
Uranium
1.6
0.011
43, p.6925;
SS25-01-
sand
(mg/kg)
104,
052518
pp.6,79;
220, p. 146
BSA-18
0-6"
Silty
sand
1805631
5/25/18
Radium-
226 (pCi/g)
1.76*
NA
43, p.6925;
200, p. 1;
104, p.11;
220,p. 152
AOC Samples - Frank Jr. IV
ine Waste Pile M14
M14-
0-6"
Waste
1809426-9
9/18/18
Arsenic
16
0.2
14, p. 192;
SS69-01-
rock
(mg/kg)
84,
091818
sand
pp.6,55;
220, p. 589
M14-
0-3"
Waste
1805632-2
5/24/18
Uranium
130
0.099
14, p.177;
XS40-
rock
(mg/kg)
115, pp.5,
01-
sand
15; 220,
052418
p.158
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Table 41. Sample Description and Analytical Results lor AOC 32
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/ardous
Substance
1 la/ardous
Substance
Cone.
Reporlin<>
Limit2
Reference
M14-
SS37-01-
091818
u-o"
Sill)
sand
1809427-8
9. 18. 18
Radiiim-
226 (pCi/g)
92 J-
NA
14,p.l9l,
84,
p.6,108;
48, pp.7,8;
220, p.592
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
J- The analyte was detected at the reported concentration; the quantitation is an estimate and may be biased
low. As a source sample, the concentration of this qualified data is reported without adjustment (Ref. 48,
P-7, 8).
Description of Areas of Concern - Mesa V and Mesa VI
Given the interconnected nature of the ore bodies, similar mining processes, similar time frames of operation,
and general geology of the LMMD site, the possible mining-related sources listed below may be releasing
hazardous substances to the Cove Wash drainages or exposing human or terrestrial sensitive environment targets.
The other areas of concern will be evaluated during further investigation of this area.
Table 42. Mesa V and Mesa VI Other Areas of Concern
Area of
Concern
Description (Reference)
NA-0318
NA-0318 is located southeast of Mesa V Adit, Mesa V Incline, and NA-0344B (Ref. 16,
p.21). NA-0318 has one waste pile, one rimstrip, and one pit. The waste pile is in the eastern-
southeastern portion of the mine area on a slope and is estimated to be 60 to 70 feet wide.
Weston conducted a gamma scan in 2010, and the highest gamma measurement was 62,742
cpm. The highest background gamma level measured was 18,000 cpm (Ref. 54, pp. 2, 3, 4,
10, 11).
Cato No. 1 Pit
Cato No. 1 Pit is located northeast of Frank Jr. Mine (Figure 1). Cato No. 1 Pit has three waste
piles, one rimstrip, and one pit. The mine was operational in 1951 (Ref. 55, pp.4,5,11,12).
Weston conducted a gamma scan in 2010, and the highest gamma measurement was 428,784
cpm, which is significantly higher than the highest background gamma level measurement of
20,400 cpm (Ref. 55, pp.3,4,11,12).
NA-0319 #469
NA-0319 #469 is located northwest of Mesa V Adit. NA-0319 #469 contains three portals.
Weston conducted a gamma scan in 2010, and the highest gamma measurement was 52,361
cpm, which is higher than the highest background gamma level measurement of 12,359 cpm
(Ref. 46, pp.3,5,17,18).
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Table 42. Mesa V and Mesa VI Oilier Areas of C 'oncern
Area of
Concern
Description (Reference)
NA-0319 #612
NA-0319 #612 shares a southern border with Mesa VI Mine. The Cove Wash North drainage
runs along the southern edge of the Mesa VI Mine boundary and flows directly through the
mine boundary of NA-0319 #612. Waste Pile M31B is located near NA-0319 #612 (Ref. 13,
pp.24,31,32). NA-0319 # 612 contains two waste piles located on steep slopes and one portal.
Weston conducted a gamma scan in 2010, and the highest gamma measurement was 239,222
cpm, which is significantly higher than the highest background gamma level measurement of
12,359 cpm (Ref. 46, pp.4,6,17,18).
Areas of Observed Contamination 33 to 36 - Knife Edge Mesa
The Knife Edge Mesa area includes four AOCs that are associated with four mine claims and a mine-related area:
Knife Edge Mesa Mine, Joleo Mine, Cisco Mine, Camp Mine, and NA-0343. NA-0343 is a mine-related area
considered to be another area of concern needing further investigation.
1 able 43. Knife Edge Mesa AOCs
AOC
AOC
Mine Claim Names
RSE Waste Pile Names
No.
Type
33
Pile
Knife Edge Mesa Mine
Waste Pile M33
34
Pile
Camp Mine
Waste Pile M52
35
Pile
Cisco Mine
Waste Pile M53A and M53B
36
Pile
Joleo Mine
Waste Pile M54
According to Chenoweth, the Knife Edge Mesa Mine was operated by VCA only in 1966 (Ref. 187, p. 57).
However, Roux Associates, Inc. states that this mine was also operated while owned and operated by Kerr-McGee
(Ref. 33, p.25). Camp Mine was operated from 1953 through 1956 by Walter Duncan and from 1962 through
1963 by Robert Goode (Ref. 173, p.2). Similarly, Walter Duncan was the listed operator at Cisco Mine in 1953
and at Joleo Mine from 1952 through 1954 (Refs. 171, p.2; 172, p.2). Operations included underground mining
that tapped paleochannels in the Salt Wash Member of the Lower Morrison Formation that are rich in uranium
and vanadium. Underground mine workings exist within the Knife Edge Mesa area. Waste piles consist of
overburden or lower grade protore discarded near or downslope of portals and adits (Refs. 33, p.26; 171, p.4; 172,
p.4; 173, p.4).
The AOC at Knife Edge Mesa Mine was sampled as part of the USEPA RSE investigation in 2018 (Ref. 33, pp. 9,
11, 134). The other three AOCs in the Knife Edge Mesa area (Camp Mine, Cisco Mine, and Joleo Mine) were
sampled during aNPL sampling event in 2022 (Ref. 186, pp. 1, 2, 3, 4). One background surface soil sample
(KNIFE BG-01) was collected during the 2022 sampling event. NA-0343 was partially scanned in 2010, but no
soil sampling was conducted at the mine by USEPA.
Number by which this AOC is to be identified: 33
Name of AOC: Knife Edge Mesa Mine Waste Pile M33
AOC Type: Pile
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Location and description of AOC (with reference to a map of the area): Figure 13
AOC 33 comprises one waste pile: Knife Edge Mesa Mine Waste Pile M33. Knife Edge Mesa Mine is a former
uranium and vanadium underground mine (33, pp.18, 26). Waste Pile M33 extends downslope for approximately
50 yards from the former portal at the Knife Edge Mesa Mine. The waste pile slopes steeply and off the edge of a
cliff and into the Knife Edge Wash below (33, pp. 20, 26, 27). Surficial contamination documented in the AOC
sample results below shows that the waste pile does not have a continuous cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile (Ref. 136, pp.50,51,71,120). Observed
contamination is established by analytical significance above background levels. For surface waste samples
analyzed for metals, observed contamination is established when the metal concentration is three times the highest
AOC-specific background concentration (Refs. 43, p.7041; 137, pp.6,71). For Ra-226, observed contamination is
established when the Ra-226 concentration is two standard deviations above the mean site-specific Ra-226
background concentration (Refs. 1, pp.14,116; 43, p.7037; 137, p.10; 200, pp. 1-2). All Ra-226 results for this
AOC also exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp. 2,3;
221, p.25; 222, pp.171-174).
BSA-32 was selected as the most appropriate background location for AOC 33 because it is within the same
geologic unit (Undifferentiated Summerville, Todilto, Entrada Formation) and it hosts soil of the same type (Ref.
33, p.22). The metals analysis was performed by ALS Environmental Laboratories using USEPA method SW-846
6020A ICP-MS (Ref. 137, pp.71,158). Ra-226 analysis was performed by ALS Environmental Laboratories using
USEPA method 901.1 gamma spectroscopy (Refs. 137, p.71, 158; 200, pp.2,3,5).
Table 44. Sample Description itiul Analytical Results lor AOC 33
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Su list a nee
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 32)
33, p.33;
43, p.3247
B32-
SS23-01-
071218
0-6"
Sandy
gravel
1807330-26
7/12/18
Uranium
(mg/kg)
21
0.01
43,
p.7041;
137, pp.6,
71; 220, p.
347
BSA-32
0-6"
Silty
sand
1807331
7/12/18
Radium-
226 (pCi/g)
15.06*
NA
43,
p.7037;
200, p.2;
137, p.10;
220, p.352
AOC Samples - Knife Edge
Mesa Mine Waste Pile M33
M33-
SS97-01-
091818
0-6"
Waste
rock
sand
1809418-19
9/18/18
Uranium
(mg/kg)
230
0.097
33, p.187;
136, pp.5,
71; 220, p.
568
M33-
SS97-01-
091818
0-6"
Waste
rock
sand
1809419-19
9/18/18
Radium-
226 (pCi/g)
152 M3
NA
33, p.187;
136, pp.
12,120;
220, p.571
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1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC.
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 34
Name of AOC: Camp Mine Waste Pile M52
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 13
AOC 34 comprises one waste pile: Camp Mine Waste Pile M52. Camp Mine was operational from approximately
1953 to 1963. Historical documents show the operator of the mine as Walter Duncan from 1953 to 1956 and
Robert Goode from 1962 to 1963. While operational, the mine had a total reported production volume of
18,853 tons of uranium ore (Ref. 173, pp. 2, 5). Surficial contamination documented in the AOC sample results
below shows that the waste pile does not have a continuous cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile (Ref. 186, pp.18,19,20,25-27,35,45,51,303).
Observed contamination is established by analytical significance above background levels. For metals,
background levels are determined based on comparison to the highest background concentration from the
background sample collected during the same sampling event (Refs. 1, pp.13,14; 186, pp.1,35,65). All AOC
sample results for Ra-226 exceed the upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp.14,116;
200, pp. 2,3; 221, p.25; 222, pp.171-174).
The metals analysis was performed by ALS Environmental Laboratories using USEPA method SW-846 6020A
ICP-MS (Ref. 186, pp.35,37). Ra 226 analysis was performed by ALS Environmental Laboratories using USEPA
method 901.1 gamma spectroscopy (Refs. 186, pp.280,282; 200, pp.3,5).
Table 45. Sample Description itiul Analytical Results lor AOC 34
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (Knife
BG-01)
186, p.l
KNIFE-
SSBG01-
072122
0-3"
Red
sand
2207536-
11
7/21/22
Arsenic
(mg/kg)
0.77
0.19
186,
pp.29,30,3
5, 66
KNIFE-
SSBG01-
072122
0-3"
Red
sand
2207536-
11
7/21/22
Lead
(mg/kg)
2.6
0.19
186,
pp.29,30,3
5, 66
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Table 45. Sample Description itiul Analytical Results lor AOC 34
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
KMIL-
SSBG01-
072122
U-3"
Red
sand
22U7530-
11
7.:i.::
I rani mil
(mg/kg)
U.24
u.uly
ISO,
pp.29,30,3
5, 66
Upper-limit range of regional
background
Radium-
226 (pCi/g)
2.23
NA
200, pp.
2,3
AOC Samples - Camp Mine Waste Pile M52
208-
SSW01-
01-
071922
0-3"
Waste
rock
sand
2207536-1
7/19/22
Arsenic
(mg/kg)
6.2
0.2
186,
pp.25,27,3
5,45
208-
SSW01-
01-
071922
0-3"
Waste
rock
sand
2207536-1
7/19/22
Lead
(mg/kg)
31
0.2
186,
pp.25,27,3
5,45
208-
SSW04-
01-
071922
0-3"
Waste
rock
sand
2207536-4
7/19/22
Uranium
(mg/kg)
8,400
2
186, pp.
26, 27, 35,
52
208-
SSW04-
01-
071922
0-3"
Waste
rock
sand
2207537-4
7/19/22
Radium-
226 (pCi/g)
1,310 M3
NA
186,
pp.26,27,3
5,303
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC.
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 35
Name of AOC: Cisco Mine Waste Pile M53A and Waste Pile M53B
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 13
AOC 35 comprises two waste piles: Cisco Mine Waste Pile M53A and Waste Pile M53B. Both waste piles are
aggregated into a single AOC because of their proximity, similar waste type, same AOC type, impacts on the
same targets, and similar past operational history. Waste Pile M53A is in the eastern portion of the mine area. The
waste piles extend around a point on the mesa (Ref. 186, p.6). Cisco Mine was operated in 1953. Historical
documents show the operator of the mine as Walter Duncan in 1953 (Refs. 172, p. 5; 186, p. 6). Surficial
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contamination documented in the AOC sample results below shows that the waste piles do not have a continuous
cover of 2 feet or greater.
All waste samples are surface samples collected from the waste piles (Ref. 186, p. 1). Observed contamination is
established by analytical significance above background levels. For surface waste samples analyzed for metals,
observed contamination is established when the metal concentration is three times the background concentration
(Ref. 186, pp. 1,2,3,6,23,29,30,35,66,318). For metals, background levels are determined based on comparison to
the highest background concentration from the background sample collected during the same sampling event
(Refs. 1, pp. 13,14; 186, pp. 1,35,65). All Ra-226 results for this AOC also exceed the upper-limit range of regional
background of 2.23 pCi/g. (Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174). The metals analysis was
performed by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Ref. 186,
pp.35,37). Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1
gamma spectroscopy (Refs. 186, pp.280,282; 200, pp.3,5).
Table 46. Sample Description itiul Analytical Results lor AOC 35
S;t in pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Dale
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Re Terence
Background Sample (Knife
3G-01)
186, pp.1,
2
KNIFE-
SSBG01-
072122
0-3"
Unava
ilable
2207536-
11
7/21/22
Arsenic
(mg/kg)
0.77
0.19
186,
pp.29,30,
35,65
KNIFE-
SSBG01-
072122
0-3"
Unava
ilable
2207536-
11
7/21/22
Lead
(mg/kg)
2.6
0.19
186,
pp.29,30,
KNIFE-
SSBG01-
072122
0-3"
Unava
ilable
2207536-
11
7/21/22
Uranium
(mg/kg)
0.24
0.019
186,
pp.29,30,
Upper-limit range of regional
background
Radium-
226 (pCi/g)
2.23
NA
200, pp.
2,3
AOC Samples - Cisco Mine Waste Piles M53A and M53B
429-
SSW01-
01-
072122
0-3"
Waste
rock
sand
2207536-5
7/21/22
Arsenic
(mg/kg)
5.5
0.2
186,
pp.29,30,
35
429-
SSW01-
01-
072122
0-3"
Waste
rock
sand
2207536-5
7/21/22
Lead
(mg/kg)
16
0.2
186,
pp.29,30,
35
429-
SSW01-
01-
072122
0-3"
Waste
rock
sand
2207536-5
7/21/22
Uranium
(mg/kg)
490
0.2
186,
pp.29,30,
35
429-
SSW01-
01-
072122
0-3"
Waste
rock
sand
2207537-5
7/21/22
Radium-
226 (pCi/g)
184 M3
NA
186,
pp.29,30,
35,305
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1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC.
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 36
Name of AOC: Joleo Mine Waste Pile M54
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 13
AOC 36 comprises one waste pile: Joleo Mine Waste Pile M36. Joleo Mine was identified as being operational
from 1952 to 1954. Historical documents show the operator of the mine as Walter Duncan from 1952 to 1954.
While operational, the mine had a total reported production volume of 10,751 tons of uranium ore (Ref. 171, p.5).
Surficial contamination documented in the AOC sample results below shows that the waste pile does not have a
continuous cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile (Ref. 186, p.l). Observed contamination is
established by analytical significance above background levels. For surface waste samples analyzed for metals,
observed contamination is established when the metal concentration is three times the highest background
concentration (Ref. 1, pp. 13,14). Background levels are determined based on the highest analyte-specific
background concentration from the AOC-specific background sample from the same sampling event (Refs. 186,
pp. 1,35,65). All Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23
pCi/g. (Refs. 1, pp. 14,116; 200, pp. 2,3; 221, p.25; 222, pp. 171-174). The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Ref. 186, pp.35,37). Ra-226 analysis
was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Refs. 186,
pp.280,282; 200, pp.3,5).
Table 47. Sample Description itiul Analytical Results lor AOC 36
S;t in pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Dale
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (Knife
BG-01)
186, p.l
KNIFE-
SSBG01-
072122
0-6"
Unava
ilable
2207536-
11
7/21/22
Arsenic
(mg/kg)
0.77
0.19
186,
pp.29,30,3
5
KNIFE-
SSBG01-
072122
0-6"
Unava
ilable
2207536-
11
7/21/22
Lead
(mg/kg)
2.6
0.19
186,
pp.29,30,3
5
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Table 47. Sample Description and Analytical Results lor AOC 36
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
IvNll L-
SSBG01-
072122
i.i-O"
L na\ a
ilable
::o753o-
11
7 :i
L ranium
(mg/kg)
o.:4
U. U ly
ISO
pp.29,30,3
5
Upper-limit range of regional
background
Radium-226
(pCi/g)
2.23
NA
200, pp.
2,3
AOC Samples - Joleo Mine Waste Pile M54
467-
SSW01-
01-
072122
0-6"
Waste
rock
sand
2207536-8
7/21/22
Arsenic
(mg/kg)
11
0.2
186,
pp.28,30,3
5
467-
SSW03-
01-
072122
0-6"
Waste
rock
sand
2207536-
10
7/21/22
Lead
(mg/kg)
13
0.2
186,
pp.28,30,3
5,
467-
SSW03-
01-
072122
0-6"
Waste
rock
sand
2207536-
10
7/21/22
Uranium
(mg/kg)
920
0.2
186,
pp.28,30,3
5
467-
SSW03-
01-
072122
0-6"
Waste
rock
sand
2207537-
10
7/21/22
Radium-226
(pCi/g)
273 M3
NA
186,
pp.28,30,3
5,
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the upper-limit range of regional background (Ref. 200, pp.2,3).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC.
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Description of Areas of Concern - Knife Edge Mesa
Given the interconnected nature of the ore bodies, similar mining processes, similar time frames of operation,
similar gamma radiation signature, and general geology of the LMMD site, the other areas of concern listed below
are likely to have releases of hazardous substances, exposing human and terrestrial sensitive environment targets.
The other possible sources and AOCs will be evaluated during further investigation of this area. Figure 13 shows
the location of the Knife Edge Mesa area of concern.
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Table 48. knife Kd»e Mesa Oilier Areas of Concern
Area of Concern
Description (Reference)
NA-0343
NA-0343 is located approximately 230 feet southeast of Knife Edge Mesa Mine on
the back side of the Lukachukai Mountains (Ref. 33, p. 18). The area contains
waste debris downslope of an adit (Ref. 49, pp.4,10,11). Weston conducted a
gamma scan in 2010, and the highest gamma measurement was 999,960 cpm,
which is significantly higher than the highest background gamma level
measurement of 11,023 cpm (Ref. 49, pp.3,10,11).
Areas of Observed Contamination - Flag Mesa Area
The Flag Mesa area includes three AOCs associated with four mine claims:
1 able 40. Hag Mesa Area AOC s
AOC
No.
AOC
Type
Mine/Claim Names
RSE Waste Pile Names
37
Pile
No. 1 Mine
W aste Piles M37A and M37B
38
Pile
Black No. 1 Mine
Waste Piles M34A and M34B
39
Pile
Black No. 2 Mine and Black
No. 2 Mine West
Waste Piles M35A, M35B, M35C, and M36
The mine claims in the Flag Mesa area were developed and operated from 1953 through 1966. Flag No. 1 Mine
was operated by the Navajo Uranium Mining Company and Kerr-McGee between 1953 and 1957 and by VCA
from 1964 through 1966; the operator from 1953 through 1957 is unknown. Black No. 1 Mine was operated by
Kerr-McGee in 1955. Black No. 2 Mine was operated from 1955 through 1957 by Kerr-McGee under mine
permit 239 issued to Koley Black. No production took place at Black No. 2 Mine from 1958 and 1963, but the
mine was reopened and operated by VCA from 1963 through 1964. Black No. 2 Mine West was operated by
Kerr-McGee in 1955, which was the only year the mine recorded ore production. However, Black No. 2 Mine
West is assumed to have been grouped under the Black No. 2 Mine lease. Operations included underground
mining that tapped paleochannels in the Salt Wash Member of the Lower Morrison Formation that are rich in
uranium and vanadium. Underground mine workings exist within the Flag Mesa area. Waste piles consist of
overburden or lower grade protore discarded near or downslope of portals (Refs. 34, pp.25,26,30; 35, pp.25,26,30;
36, pp.25,26,30; 37, pp.25,27,30).
Soil is the only sample medium for background samples, and mine waste is the medium for the AOC samples
referenced below. Only surface sample results (6 inches or shallower) are presented below.
Number by which this AOC is to be identified: 37
Name of AOC: Flag No. 1 Mine Waste Pile M37A and Waste Pile M37B
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 14
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AOC 37 comprises two waste piles: Flag No. 1 Mine Waste Pile M37A and Waste Pile M37B. Both waste piles
are aggregated into a single AOC because of their proximity, similar waste type, same AOC type, impacts on the
same targets, and similar past operational history. Waste Pile M37B is part of Waste Pile M37A except that the
piles are separated by a cliff; overflow waste from Waste Pile M37A has fallen downhill to create Waste Pile
M37B on a geographically lower bench (Ref. 37, p.27). Flag No. 1 Mine was operated by Navajo Uranium
Mining Company and Kerr-McGee between 1953 and 1957 and by VCA between 1964 and 1966; the operator
from 1957 to 1964 is currently unknown. In total, the mine produced 11,286 tons of ore (Ref. 37, p.25). Surficial
contamination documented in the AOC sample results below shows that the waste piles do not have a continuous
cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile (Ref. 37, p.136; 134, pp.5,9,50,91). Observed
contamination is established by analytical significance above background levels. For surface waste samples
analyzed for metals, observed contamination is established when the metal concentration is three times the
background concentration (Refs. 1, p. 13; 43, p.7041). For Ra-226, observed contamination is established when
the Ra-226 concentration is two standard deviations above the mean site-specific Ra-226 background
concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for this AOC also exceed the upper-limit
range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp. 2,3; 221, p.25; 222, pp. 171-174).
BSA-32 was selected as the most appropriate background location for AOC 38 because it is within the same
geologic unit (undifferentiated Summerville and Entrada Formations) and it hosts soil of the same type (Ref. 34,
p.22). The metals analysis was performed by ALS Environmental Laboratories using USEPA method SW-846
6020A ICP-MS (Ref. 134, p.2). Ra-226 analysis was performed by ALS Environmental Laboratories using
USEPA method 901.1 gamma spectroscopy (Refs. 134, p.2; 200, pp.2,3,5).
Table 50. Sample Description itiul Analytical Results lor AOC 37
S;t in pie
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Dale
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 32)
34, p.33;
43, p.3249
B32-
SS23-
01-
071218
0-6"
Sandy
gravel
1807330-26
7/12/18
Uranium
(mg/kg)
21
0.01
43, p.7041;
137,
pp.6,71;
220,
pp.343,
344
BSA-32
0-6"
Silty
sand
1807331
7/12/18
Radium-226
(pCi/g)
15.06*
NA
43,
pp.7036,
7037; 200,
p.2; 137,
p. 10; 220,
p.352
AOC Samples - F
ag No. 1 Mine Waste Pile M37A and Waste Pile
M37B
M37-
XS124
A-01-
081318
0-3"
Waste
rock
sand
1808303-16
8/13/18
Uranium
(mg/kg)
240
0.095
37, p.165;
134,
pp.5,50;
220,
pp.422,
423
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Tstble 50. Ssiniple Description itiul Anstlyticsil Results lor AOC 37
Sstmplc
II)
Sstmplc
Depth
Soil
Type1
Lstborstlory
Sum p lo 11)
Dstlc
1 Ist/sirilous
Subsist n cc
1 Ist/sirilous
Subsist n ce
Cone.
Reporting
Limit2
Reference
M37-
XS124
A-01-
081318
n-3"
\\ ask-
rock
sand
1S(IS3o:-10
X 13 IS
Riidium-^0>
(pCi/g)
145 \13
\A
37, P. 165,
134,
pp.9,91;
220,
pp.417,
418
Waste samples from the mine waste pi
es are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC (Ref. 134, p. 91).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 38
Name of AOC: Black No. 1 Mine Waste Pile M34A and Waste Pile M34B
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 14
AOC 38 comprises two waste piles: Black No. 1 Mine Waste Pile M34A and Waste Pile M34B. Both waste piles
are aggregated into a single AOC because of their proximity, similar waste type, same AOC type, impacts on the
same targets, and similar past operational history. Waste Pile M34B is part of Waste Pile M34A except that the
piles are separated by a cliff; overflow waste from Waste Pile M34A has fallen downhill to create Waste Pile
M34B on a geographically lower bench (Ref. 34, p.26). The Black No. 1 Mine was operated in 1955 by Kerr-
McGee and produced 1,047 tons of ore (Ref. 34, p.25). Surficial contamination documented in the AOC sample
results below shows that the waste piles do not have a continuous cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile (Ref. 34, p.12; 134, pp.5,9,50,91). Observed
contamination is established by analytical significance above background levels. For surface waste samples
analyzed for metals, observed contamination is established when the metal concentration is three times the
background concentration (Refs. 1, p. 13,14; 43, p.7041). For Ra-226, observed contamination is established when
the Ra-226 concentration is two standard deviations above the mean site-specific Ra-226 background
concentration (Refs. 1, p.l 16; 200, pp. 1-2). All Ra-226 results for this AOC also exceed the upper-limit range of
regional background of 2.23 pCi/g. (Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174).
BSA-32 was selected as the most appropriate background location for AOC 38 because it is within the same
geologic unit (undifferentiated Summerville and Entrada Formations) and it hosts soil of the same type (Ref. 34,
p.22). The metals analysis was performed by ALS Environmental Laboratories using USEPA method SW-846
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6020A ICP-MS (Ref. 101, p.2). Ra-226 analysis was performed by ALS Environmental Laboratories using
USEPA method 901.1 gamma spectroscopy (Refs. 101, p.2; 200, pp.2,3,5).
Table 51. Sample Description itiul Analytical Results lor AOC 38
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
Background Sample (BSA 32)
34, p.33;
43, p.3247
B32-
0-6"
Sandy
1807330-
7/12/18
Uranium
21
0.01
43,
SS23-01-
071218
gravel
26
(mg/kg)
p.7041;
137,
pp.6,71;
220,
pp.343,
344
BSA-32
0-6"
Silty
sand
1807331
7/12/18
Radium-226
(pCi/g)
15.06*
NA
43,
pp.7036,
7037; 137,
p. 10; 200,
p.2; 220,
p.352
AOC Samples - Black No. 1 Mine Waste Pile M34A and Waste Pile M34B
M34-
0-6"
Silty
1810080-4
9/27/18
Uranium
190
0.1
34, p.189;
SS109-
sand
(mg/kg)
101,
01-
pp.7,54;
092718
220,
pp.799,
800
M34-
0-6"
Silty
1810079-4
9/27/18
Radium-226
122 M3
NA
34, p.189;
SS109-
sand
(pCi/g)
101,
01-
pp.17,157;
092718
220,
pp.791,
792
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC (Ref. 101, p. 157).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
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Number by which this AOC is to be identified: 39
Name of AOC: Black No. 2 Mine and Black No. 2 Mine West Waste Pile M35A, Waste Pile M35B, Waste Pile
M35C, and Waste Pile M36
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 14
AOC 39 comprises four waste piles: Black No. 2 Mine and Black No. 2 Mine West Waste Pile M35A, Waste Pile
M35B, Waste Pile M35C, and Waste Pile M36. All four waste piles are aggregated into a single AOC because of
their proximity, similar waste type, same AOC type, impacts on the same targets, and similar past operational
history. Kerr-McGee began production of the two Black Mesa mine claims located on the south side of the
Lukachukai Mountains in 1955. This was the only year the mines were identified as producing ore. Black No. 2
Mine (also known as Bare Rock Mesa Mine) is contiguous with Black No. 2 Mine West and under Koley Black's
MP-239 lease (Ref. 187, p.63). Black No. 2 Mine West production was grouped under this lease with Black No. 2
Mine for a total of 1,879 tons of ore produced (Ref. 187, p. 63). The two sites together had two primary portals,
one of which was accessible and one of which was not. Both were open with highwalls and had associated waste
piles and wooden debris and structures (Ref. 35, p.28). Surficial contamination documented in the AOC sample
results below shows that the waste piles do not have a continuous cover of 2 feet or greater.
All waste samples are surface samples collected from the waste pile (Ref. 35, p. 163). Observed contamination is
established by analytical significance above background levels. For surface waste samples analyzed for metals,
observed contamination is established when the metal concentration is three times the background concentration
(Refs. 1, p. 13,14; 43, p.7041). For Ra-226, observed contamination is established when the Ra-226 concentration
is two standard deviations above the mean site-specific Ra-226 background concentration (Refs. 1, p.l 16; 200,
pp. 1-2). All Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g.
(Refs. 1, pp. 14,116; 200, pp. 2,3; 221, p.25; 222, pp. 171-174).
BSAs 32 and 33 are approximately equidistant from AOC 39, therefore data from both BSAs are provided. All
AOC samples exceed the highest value from both BSAs. The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Ref. 134, p.2). Ra-226 analysis was
performed by ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Refs. 134, p.2;
200, pp.2,3,5).
Table 52. Sample Description and Analytical Results lor AOC 31)
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (BSA 33)
35, p.33;
43, p.3357
B33-
SS08-01-
071618
0-6"
Silty
sand
1807367-11
7/16/18
Uranium
(mg/kg)
1.9
0.011
43, p.7047;
138,
pp.6,40;
220,
pp.401,
402
BSA-33
0-6"
Silty
sand
1807368
7/16/18
Radium-
226 (pCi/g)
1.98*
NA
43,
pp.7044,
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Table 52. Sample Description and Analytical Results lor AOC 31)
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
7045; 138,
p. 10; 200,
p.2; 220,
p.407
AOC Samples - Black No. 2 Mine Waste Pile M35A, Waste Pile M35B, and Waste Pile M35C
M35-
0-3"
Waste
1808303-10
8/13/18
Uranium
90
0.093
35, p.163;
XS74-
01-
rock
sand
(mg/kg)
134, pp.5,
38; 220,
081318
pp.422,
423
M35-
0-3"
Waste
1808302-11
8/13/18
Radium-
102 M3
NA
35, p.163;
XS74-
rock
226 (pCi/g)
134, pp.9,
02-
sand
81; 220,
081318
pp.417,
418
Background Sample (BSA 32)
34, p.33;
43, p.3247
B32-
0-6"
Sandy
1807330-26
7/12/18
Uranium
21
0.01
43, p.7041;
SS23-01-
071218
gravel
(mg/kg)
137, pp.6,
71; 220,
pp.343,
344
BSA-32
0-6"
Silty
sand
1807331
7/12/18
Radium-
226 (pCi/g)
15.06*
NA
43, p.7041;
137, p.10;
200, p.2;
220, p.352
AOC Samples - Black No. 2 Mine, West Waste Pile IV
[36
M36-
0-3"
Waste
1808303-15
8/12/18
Uranium
110
0.097
36, p.170;
XS31-
01-
rock
sand
(mg/kg)
134, pp.5,
48; 220,
081218
pp.422,
423
M36-
0-3"
Waste
1808302-15
8/12/18
Radium-
107 M3
NA
36, p.170;
XS31-
01-
rock
sand
226 (pCi/g)
134, pp.9,
89; 220,
081218
pp.417,
418
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).s
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M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC (Ref. 134, p. 81).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Areas of Observed Contamination 40 to 43 - Step Mesa
Four AOCs are scored as a result of mining activities at Step Mesa.
Table 53. Step Mesa AOCs
AOC
No.
AOC
Typo
Mine/C laim Names
RSE Waste Pile Names
40
Pile
Step Mesa Mine
Step Mesa Mine \\ aslc Pile \ 13 X
41
Pile
Jimmie King No. 9
Jimmie King No. 9 Waste Pile
42
Pile
NA-0332
NA-0332 Waste Pile
43
Pile
NA-0333
NA-0333 Waste Pile
All mine claims and mine-related areas are in the Step Mesa geographic area (Ref. 38, p.20). In 1961, Kerr-
McGee acquired the Tommy James Mine mining permit (MP-109) lease and began to develop the area. VCA
acquired the Step Mesa Mine lease in 1963 and continued operating the area through 1964 (Ref. 38, p.25).
Tommy James Mine was operated by Price Exploration from 1955 through 1956 (Ref. 39, p. 18). Jimmie King
No. 9 Mine (also known as NA-0334) was operated by Warren and Dye from 1956 through 1957 and by E.D.
Warren in 1957 (Ref. 170, p. 2). Operations included underground mining that tapped paleochannels in the Salt
Wash Member of the Lower Morrison Formation that are rich in uranium and vanadium (Refs. 38, p.22; 39, p. 15).
Underground mine workings exist throughout the Step Mesa area. Waste piles consist of overburden or lower
grade protore discarded near or downslope of portals (Refs. 38, p.30; 39, p.23; 183, p. 18). Mine-related features
NA-0332 and NA-0333 were identified by NAML under the Northern Navajo Cove 4 Project in 2004 (Refs 65,
p.71; 215, p. 3; 216. P. 3). Waste Pile NA-0332 is located east of Tommy James Mine, and Waste Pile NA-0333
is located north of Waste Pile NA-0332 (Figure 15).
Soil is the only sample medium for background samples, and mine waste is the medium for the AOC samples
referenced below. Waste pile observed contamination is established by analytical significance as compared to
surface soil background levels (Ref. 1, p. 14). Only surface sample results (6 inches or shallower) are presented
below. Select other possible AOC samples are presented below to demonstrate that the observed contamination
criteria are met.
Number by which this AOC is to be identified: 40
Name of AOC: Step Mesa Mine Waste Pile M38
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 15
AOC 40 comprises one waste pile: Step Mesa Mine Waste Pile M38. The waste generated is a result of mine
operations in ore bodies within the Salt Wash Member of the Lower Morrison Formation (Ref. 38, p.27).
Surficial contamination documented in the AOC sample results below shows that the waste pile does not have a
continuous cover of 2 feet or greater.
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All waste samples are surface samples collected from the waste pile. Observed contamination is established by
analytical significance as compared to background levels (Ref. 1, p. 14). For surface waste samples analyzed for
metals, samples are compared to the highest background concentrations for each analyte from surface
background samples near the AOC (Refs. 35, p.33; 43, p.3355). For Ra-226, observed contamination is
established when the Ra-226 concentration is two standard deviations above the mean site-specific Ra-226
background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for this AOC also exceed the
upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp. 2,3; 221, p.25; 222,
pp.171-174). The metals analysis was performed by ALS Environmental Laboratories using USEPA method
SW-846 6020A ICP-MS. Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA
method 901.1 gamma spectroscopy (Refs. 38, p.170; 43, pp.7045,7047,7048; 98, pp.7,14,113,206; 138, pp.
6,10,40,44).
BSA-33 was selected as the most appropriate background location for AOC 40 because it is within the same
geologic unit (Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC (Refs. 43,
pp. 3338; 212, p. 1). The highest background concentration for each metals analyte from the 30 samples
comprising BSA-33 was used as the background level for AOC 40 (Ref. 43, p.3358). The Ra-226 mean plus two
standard deviations from the 30 samples comprising BSA-33 was used as the background level for AOC 40
(Refs. 43, pp. 3361; 200, p.2).
Table 54. Sample Description and Analytical Results lor AOC 40
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Samp
e (BSA 33)
35, p.33;
43, pp.
3355, 3357
B33-
SS10-
01-
071618
0-6"
Sand
1807367-13
7/16/18
Arsenic
(mg/kg)
1.7
0.21
43, p.7048;
138, pp.6,
44; 220,
pp.401,
402, 404
B33-
SS08-
01-
071618
0-6"
Silty
sand
1807367-11
7/16/18
Uranium
(mg/kg)
1.9
0.011
43, p.7047;
138, pp.6,
40; 220,
pp.401,
402, 404
BSA-33
0-6"
Silty
sand
1807368
7/16/18
Radium-
226 (pCi/g)
1.98*
NA
43,
pp.7044,
7045; 200,
p.2; 138,
p. 10; 220,
p.407
AOC Samples - Step Mesa
Mine Waste Pile M38
M38-
SS2-01-
092718
0-6"
Silty
sand
1810026-36
9/27/18
Arsenic
(mg/kg)
13
0.19
38, p.170;
98, pp.7,
113; 220,
pp.726,
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131
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Tnhle 54. Siimplo Description
-------
performed by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-MS. Ra-226 analysis
was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Refs. 43,
pp.7045,7047,7048; 138, pp.6,10,40,44; 197, pp.6,19; 204, pp.6,24).
BSA-33 was selected as the most appropriate background location for AOC 41 because it is within the same
geologic unit (Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC (Refs. 43,
pp. 3338; 212, p. 1). The highest background concentration for each metals analyte from the 30 samples
comprising BSA-33 was used as the background level for AOC 41 (Ref. 43, p.3358). The Ra-226 mean plus two
standard deviations from the 30 samples comprising BSA-33 was used as the background level for AOC 41 (Refs.
43, pp. 3361; 200, p.2).
Table 55. Sample Description itiul Analytical Results lor AOC 41
S:i m pic
Sample
Soil
Laboratory
Date
1 lazarilous
1 la/arilous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Su list a lice
Substance
Cone.
Limit2
Background Sample (BSA 33)
35, p.33;
43, p.3355
B33-
0-6"
Sand
1807367-
7/16/18
Arsenic
1.7
0.21
43, p.7048;
SS10-01-
13
(mg/kg)
138,
071618
pp.6,44;
220, p. 404
B33-
0-6"
Silty
1807367-
7/16/18
Uranium
1.9
0.011
43, p.7047;
SS08-01-
sand
11
(mg/kg)
138,
071618
pp.6,40;
220, p. 404
BSA-33
0-6"
Silty
sand
1807368
7/16/18
Radium-
226 (pCi/g)
1.98*
NA
43, p.7045;
200, p.2;
138, p.10;
220, p.407
AOC Samples - Jimmie King No. 9 Mine Waste Pile
200-
0-6"
Waste
596530001
10/04/22
Arsenic
18.5
1.0
212, pp. 12,
SSW01-
rock
(mg/kg)
13,23,35
01-
sand
100422
200-
0-6"
Waste
596530001
10/04/22
Uranium
2,450
0.83
212, pp. 12,
SSW01-
rock
(mg/kg)
13,23,35
01-
sand
100422
200-
0-6"
Waste
596534001
10/04/22
Radium-
319
NA
212,
SSW01-
rock
226 (pCi/g)
pp. 13,890,9
01-
sand
08
100422
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
HRS Documentation Record
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NNN000920223
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Number by which this AOC is to be identified: 42
Name of AOC: NA-0332 Waste Pile
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 15
AOC 42 comprises one waste pile: Waste Pile NA-0332. The waste generated is a result of mine operations in ore
bodies within the Salt Wash Member of the Lower Morrison Formation (Refs. 60, p.4; 212, p. 1). Surficial
contamination documented in the AOC sample results below shows that the waste pile does not have a continuous
cover of 2 feet or greater.
All waste samples are surface samples from the waste pile. Observed contamination is established by analytical
significance as compared to background levels (Ref. 1, p. 14). For surface waste samples analyzed for metals,
samples are compared to the highest background concentrations for each analyte from surface background
samples near the AOC (Refs. 35, p.33; 43, p.3355). For Ra-226, observed contamination is established when the
Ra-226 concentration is two standard deviations above the mean site-specific Ra-226 background concentration
(Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for this AOC also exceed the upper-limit range of regional
background of 2.23 pCi/g. (Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174). The metals analysis was
performed by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-MS. Ra-226 analysis
was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Refs. 43,
pp.7045,7047,7048; 138, pp. 6,10,40,44; 200, p.2; 197, pp.6,32,35,37; 204, pp.6,32).
BSA-33 was selected as the most appropriate background location for AOC 42 because it is within the same
geologic unit (Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC (Refs. 43,
pp. 3338; 212, p. 1). The highest background concentration for each metals analyte from the 30 samples
comprising BSA-33 was used as the background level for AOC 42 (Ref. 43, p.3358). The Ra-226 mean plus two
standard deviations from the 30 samples comprising BSA-33 was used as the background level for AOC 42 (Refs.
43, pp. 3361; 200, p.2).
Table 56. Sample Description and Analytical Results lor AOC 42
Sample
II)
Sain pic
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Report in»
Limit2
Reference
Background Sample (BSA 33)
35, p.33;
43, p.3355
B33-
SS10-01-
071618
0-6"
Sand
1807367-13
7/16/18
Arsenic
(mg/kg)
1.7
0.21
43,
p.7048;
138, pp. 6,
44; 220,
p. 404
B33-
SS08-01-
071618
0-6"
Silty
sand
1807367-11
7/16/18
Uranium
(mg/kg)
1.9
0.011
43,
p.7047;
138, pp. 6,
HRS Documentation Record
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Lukachukai Mountains Mining District
NNN000920223
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Table 56. Sample Description and Analytical Results lor AOC 42
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Report in»
Reference
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
40; 220,
p. 404
BSA-33
0-6"
Silty
sand
1807368
7/16/18
Radium-
226 (pCi/g)
1.98*
NA
43,
p.7045;
200, p.2;
138, p.10;
220, p.407
AOC Samples - NA-0332 Waste Pile
202-
0-3"
Waste
596530010
10/04/22
Arsenic
18.5
0.96
212, pp.
SSW03-
rock
(mg/kg)
12, 15,23,
01-
sand
53
100422
202-
0-6"
Waste
596530009
10/04/22
Uranium
1,290
0.40
212, pp.
SSW02-
rock
(mg/kg)
12, 15,23,
01-
sand
51
100422
202-
0-6"
Waste
596534009
10/04/22
Radium-
406
NA
212,
SSW02-
rock
226 (pCi/g)
pp.15,890,
01-
sand
916
100422
Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2. The reporting limit is equivalent to the sample quantitation limit as defined by HRS, section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 43
Name of AOC: NA-0333 Waste Pile
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 15
AOC 43 comprises one waste pile: Waste Pile NA-0333. The waste generated is a result of mine operations in
ore bodies within the Salt Wash Member of the Lower Morrison Formation (Refs. 61, p.4; 212, p. 1). Surficial
contamination documented in the AOC sample results below shows that the waste pile does not have a
continuous cover of 2 feet or greater.
HRS Documentation Record
135
Lukachukai Mountains Mining District
NNN000920223
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All waste samples are surface samples from the waste pile. Observed contamination is established by analytical
significance as compared to background levels (Ref. 1, p. 14). For surface waste samples analyzed for metals,
samples are compared to the highest background concentrations for each analyte from surface background
samples near the AOC (Refs. 35, p.33; 43, p.3355). For Ra-226, observed contamination is established when the
Ra-226 concentration is two standard deviations above the mean site-specific Ra-226 background concentration
(Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for this AOC also exceed the upper-limit range of regional
background of 2.23 pCi/g. (Refs. 1, pp. 14,116; 200, pp. 2,3; 221, p.25; 222, pp. 171-174). The metals analysis
was performed by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-MS. Ra-226
analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy
(Refs. 43, pp. 7045,7047,7048; 138, pp. 6,10,40,44; 200, p. 2; 197, pp.6,27,31; 204, pp. 6,30).
BSA-33 was selected as the most appropriate background location for AOC 43 because it is within the same
geologic unit (Morrison Formation), it hosts soil of the same type, and it is the closest BSA to the AOC (Refs. 43,
pp. 3338; 212, p. 1). The highest background concentration for each metals analyte from the 30 samples
comprising BSA-33 was used as the background level for AOC 43 (Ref. 43, p.3358). The Ra-226 mean plus two
standard deviations from the 30 samples comprising BSA-33 was used as the background level for AOC 43
(Refs. 43, pp. 3361; 200, p.2).
Table 57. Sample Description and Analytical Results lor AOC 43
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Reference
II)
Depth
Type1
Sample 11)
Substance
Substance
Cone.
Limit2
Background Sample (BSA 33)
35, p.33;
43, p.3355
B33-
0-6"
Sand
1807367-
7/16/18
Arsenic
1.7
0.21
43, p.7048;
SS10-01-
13
(mg/kg)
138, pp. 6,
071618
44; 220, p.
404
B33-
0-6"
Silty
1807367-
7/16/18
Uranium
1.9
0.011
43, p.7047;
SS08-01-
sand
11
(mg/kg)
138, pp. 6,
071618
40; 220, p.
404
BSA-33
0-6"
Silty
sand
1807368
7/16/18
Radium-
226 (pCi/g)
1.98*
NA
43, p.7045;
200, p.2;
138, p.10;
220, p.407
AOC Samples - NA-0333 Waste Pile
201-
0-3"
Waste
596530005
10/04/22
Arsenic
16.1
0.94
212, pp. 12,
SSW02-
rock
(mg/kg)
14, 22, 43
02-
sand
100422
201-
0-3"
Waste
596530007
10/04/22
Uranium
2,040
0.41
212, pp. 12,
SSW03-
rock
(mg/kg)
14, 22, 47
01-
sand
100422
201-
0-3"
Waste
596534007
10/04/22
Radium-
480
NA
212, pp. 12,
SSW03-
rock
226 (pCi/g)
14, 890,
01-
sand
914
100422
HRS Documentation Record
136
Lukachukai Mountains Mining District
NNN000920223
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1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Description of Other Areas of Concern - Step Mesa
Given the interconnected nature of the ore bodies, similar mining processes, similar time frames of operation,
and general geology of the LMMD site, the other area of concern listed below may be releasing hazardous
substances to drainages below or exposing human or terrestrial sensitive environment targets. The other area of
concern will be evaluated during further investigation of this area. Figure 15 shows the location of the other area
of concern at Step Mesa area.
Table 58. Slop Mesa Oilier Areas ol'Concern
Oilier Area of
Concern
Description (Reference)
Tommy James Mine
Waste Pile M39A and
Waste Pile M39B
Field sampling activities at Tommy James Mine excluded both inaccessible waste
piles (Ref. 183, p. 18)
Areas of Observed Contamination 44 to 48 - Mexican Cry Mesa
Five AOCs are scored as a result of mining activities at Mexican Cry Mesa.
Table 59. Mexican Cry Mesa AOCs
AOC
No.
AOC
Type
Mine Claim Names
RSE Waste Pile Names
44
Pile
Mexican Cry Mine - 197
Mexican Cry 197 Waste Pile
45
Pile
Mexican Cry Mine - 198
Mexican Cry 198 Waste Pile
46
Pile
Hall Mine
Hall Mine Waste Pile
47
Pile
Nakai Chee Begay Mine
Nakai Chee Begay Waste Pile
48
Pile
Tom Joe No. 6
Tom Joe No. 6 Waste Pile
All mine claims in the Mexican Cry Mesa geographic area were developed and operated from 1955 through 1963.
Mexican Cry Mine - 197 and Mexican Cry Mine - 198 were operated by the Texas Mining Company in 1955
(Ref. 176, p.2). Hall Mine was operated by W.B. Hall from 1956 through 1958 (Ref. 177, p.2). Nakai Chee Begay
Mine was operated by Marcy Exploration from 1955 through 1956, J.W. Hall in 1956, and W.B. Hall from 1956
through 1960 (Ref. 178, p.2). Tom Joe No. 6 was operated by James W. Hall in 1963 (Ref. 179, p.2). Operations
included underground mining that tapped paleochannels in the Salt Wash Member of the Lower Morrison
Formation that are rich in uranium and vanadium (Ref. 187, p. 33). Underground mine workings exist within the
Mexican Cry Mesa area. Waste piles consist of overburden or lower grade protore discarded near or downslope of
portals (Refs. 176, p.5; 177, p.4; 178, p.4; 179, p.4).
HRS Documentation Record
137
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NNN000920223
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Number by which this AOC is to be identified: 44
Name of AOC: Mexican Cry Mine 197 Waste Pile
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 16
AOC 44 comprises one waste pile: Mexican Cry Mine 197 Waste Pile. Mexican Cry Mine consists of two mine
claims, Mexican Cry Mine - 197 and Mexican Cry Mine - 198. Mexican Cry Mine - 197 was operated in 1955
by the Texas Mining Company. While operational, the mine had a total reported ore production volume of 57 tons
(Ref. 176, p. 7). The waste generated is a result of mine operations in ore bodies within the Salt Wash Member of
the Lower Morrison Formation (Ref. 213, p.l). Surficial contamination documented in the AOC sample results
below shows that the waste pile does not have a continuous cover of 2 feet or greater.
All waste samples are surface samples from the waste pile. Observed contamination is established by analytical
significance as compared to background levels (Ref. 1, p. 14). For surface waste samples analyzed for metals,
samples are compared to the highest background concentrations for each analyte from surface background sample
MexCry-SSBG-01-092922 which is the nearest background sample to the AOC (Refs. 196, pp.6,20; 203,
pp.6,22). All Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g.
(Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174). The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS. Ra 226 analysis was performed by
ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Refs. 194, pp. 6,24,26; 201,
pp.6,25).
Table 60. Sample Description
and Analytical Results
lor AOC 44
Sample 11)
Sa in pie
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Reference
Depth
Type'
Sample 1D
Su list a nee
Substance
Cone.
Limit2
Background Sample (Background - MexCry BG-01)
MexCry-
0-6"
Silty
596526001
9/29/22
Arsenic
0.829 BN
0.96
213, pp.
SSBG-01-
sand
(mg/kg)
22, 28, 35
092922
MexCry-
0-6"
Silty
596526001
9/29/22
Uranium
0.408*
0.039
213, pp.
SSBG-01-
sand
(mg/kg)
22, 28, 35
092922
Upper-limit range of regional background
Radium-226
(pCi/g)
2.23
NA
200, pp.
2,3
AOC Samples - Mexican Cry Mine 197 Waste Pile
197-
0-6"
Waste
596484003
9/28/22
Arsenic
8.9
0.98
213, pp.
SSW02-
rock
(mg/kg)
17, 1556,
01-
sand
1573
092822
197-
0-6"
Waste
596484004
9/28/22
Uranium
445
0.040
213, pp.
SSW03-
rock
sand
(mg/kg)
17, 1556,
1575
HRS Documentation Record
138
Lukachukai Mountains Mining District
NNN000920223
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Tnhle 60. Siimplo Description ;inil An;ilytic;il Results lor AOC 44
Siimple 11)
Ssimple
Depth
Soil
Type1
l.iihomtory
Ssimple 11)
l):itc
1 l;i/:iriloiis
Substance
1 hi/iirdous
Substance
Cone.
Report in»
Limit2
Reference
01-
092822
197-
SSW03-
01-
092822
0-6"
Waste
rock
sand
596507004
9/28/22
Radium-226
(pCi/g)
71.2
NA
213,
pp.17,
2147,
2166
* A quality control analyte recovery is outside of the specified acceptance criteria.
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
B Either the analyte was detected in the associated blank or MDL/IDL < sample value < PQL.
N The matrix spike sample recovery is not within the specified control limits.
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 45
Name of AOC: Mexican Cry Mine 198 Waste Pile
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 16
AOC 45 comprises one waste pile: Mexican Cry Mine 198 Waste Pile. Mexican Cry Mine consists of two mine
claims, Mexican Cry Mine - 197 and Mexican Cry Mine - 198. Mexican Cry Mine - 198 was operated in 1955
by the Texas Mining Company in 1955. The reported ore production tonnage of 57 tons is likely combined with
Mexican Cry Mine - 197 (Ref. 176, p. 7). The waste generated is a result of mine operations in ore bodies within
the Salt Wash Member of the Lower Morrison Formation (Ref. 213, p. 1). Surficial contamination documented in
the AOC sample results below shows that the waste pile does not have a continuous cover of 2 feet or greater.
All waste samples are surface samples from the waste pile. Observed contamination is established by analytical
significance as compared to background levels (Ref. 1, p. 14). For surface waste samples analyzed for metals,
samples are compared to the highest background concentrations for each analyte from surface background sample
MexCry-SSBG-01-092922 which is the nearest background sample to the AOC (Refs. 196, pp.6,20; 203,
pp.6,22). All Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g.
(Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174). The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS (Refs. 194, pp. 6,20; 201, pp.6,22).
Ra 226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Refs. 194, pp. 6,20; 201, pp.6,22).
HRS Documentation Record
139
Lukachukai Mountains Mining District
NNN000920223
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Table 61. Sample Description
and Analytical Results lor AOC 45
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Reference
II)
Depth
Type'
Sample 11)
Substance
Substance
Cone.
Limit2
Background Sample (Background - MexCry BG-01)
MexCry-
0-6"
Silty
596526001
9/29/22
Arsenic
0.83 BN
0.96
213,
SSBG-01-
sand
(mg/kg)
pp.21,22,2
092922
8,42
MexCry-
0-6"
Silty
596526001
9/29/22
Uranium
0.41*
0.039
213,
SSBG-01-
092922
sand
(mg/kg)
pp.21,22,2
8,42
Upper-limit range of regional background
Radium-
226 (pCi/g)
2.23
NA
200, pp.
2,3
AOC Sample(s) (Mexican Cry Mine - 198)
198-
0-6"
Waste
596484001
9/28/22
Arsenic
11.2
0.97
213,
SSW01-
rock
(mg/kg)
pp.16,155
01-
sand
5,1556,
092822
1569
198-
0-6"
Waste
596484001
9/28/22
Uranium
10.7
0.039
213,
SSW01-
rock
(mg/kg)
pp.16,155
01-
sand
5,1556,
092822
1569
198-
0-6"
Waste
596507001
9/28/22
Radium-
6.16
NA
213,
SSW01-
01-
rock
sand
226 (pCi/g)
pp.16,
2147,
092822
2148,
2163
* A quality control analyte recovery is outside of the specified acceptance criteria.
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
B Either the analyte was detected in the associated blank or MDL/IDL < sample value < PQL.
N The matrix spike sample recovery is not within the specified control limits.
Number by which this AOC is to be identified: 46
Name of AOC: Hall Mine Waste Pile
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 16
AOC 46 comprises one waste pile: Hall Mine Waste Pile. Hall Mine was operated from 1956 to 1958 by W.B.
Hall. While operational, the mine had a total reported ore production volume of 2,448 tons (Ref. 177, p.5). The
waste generated is a result of mine operations in ore bodies within the Salt Wash Member of the Lower
Morrison Formation (Ref. 213, p. 1). Surficial contamination documented in the AOC sample results below
shows that the waste pile does not have a continuous cover of 2 feet or greater.
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All waste samples are surface samples from the waste pile. Observed contamination is established by analytical
significance as compared to background levels (Ref. 1, p. 14). For surface waste samples analyzed for metals,
samples are compared to the highest background concentrations for each analyte from surface background
sample MexCry-SSBG-01-092922 which is the nearest background sample to the AOC (Refs. 196, pp.6,20; 203,
pp.6,22). All Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/
g. (Refs. 1, pp. 14,116; 200, pp. 2,3; 221, p.25; 222, pp. 171-174). The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS. Ra 226 analysis was performed by
ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Refs. 196, pp. 6,20; 203,
pp. 6,22).
Table 62. Sample Description and Analytical Results lor AOC 4ft
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Reference
II)
Depth
Type'
Sample 11)
Substance
Substance
Cone.
Limit2
Background Sample (Background - MexCry BG-01)
MexCry-
0-6"
Silty
596526001
9/29/22
Arsenic
0.829 BN
0.96
213, pp.
SSBG-01-
sand
(mg/kg)
22, 28, 35
092922
MexCry-
0-6"
Silty
596526001
9/29/22
Uranium
0.408 *
0.039
213, pp.
SSBG-01-
sand
(mg/kg)
22, 28, 35
092922
Upper-limit range of regional background
Radium-
226 (pCi/g)
2.23
NA
200, pp.
2,3
AOC Samples - Hall Mine Waste Pile
468-
0-6"
Waste
596516003
9/29/22
Arsenic
17.4 N
1.03
213, pp.
SSW01-
rock
(mg/kg)
21,2887,
01-
sand
2904
092922
468-
0-6"
Waste
596516004
9/29/22
Uranium
1,380 *
0.412
213, pp.
SSW02-
rock
(mg/kg)
21,2887,
01-
sand
2906
092922
468-
0-6"
Waste
596524003
9/29/22
Radium-
69.5
NA
213, pp.
SSW01-
rock
226 (pCi/g)
21,4088,
01-
sand
4104
092922
* A quality control analyte recovery is outside of the specified acceptance criteria.
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
B Either the analyte was detected in the associated blank or MDL/IDL < sample value < PQL.
N The matrix spike sample recovery is not within the specified control limits.
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
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Number by which this AOC is to be identified: 47
Name of AOC: Nakai Chee Begay Waste Pile
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 16
AOC 47 comprises one waste pile: Nakai Chee Begay Waste Pile. Nakai Chee Begay Mine was operated by
Marcy Exploration from 1955 to 1956, W.B. Hall from 1956 to 1960, and J.W. Hall in 1956. While operational,
the mine had a total reported ore production volume of 399 tons (Ref. 178, p.5). The waste generated is a result of
mine operations in ore bodies within the Salt Wash Member of the Lower Morrison Formation (Ref. 213, p. 1).
Surficial contamination documented in the AOC sample results below shows that the waste pile does not have a
continuous cover of 2 feet or greater.
All waste samples are surface samples from the waste pile. Observed contamination is established by analytical
significance as compared to background levels (Ref. 1, p. 14). For surface waste samples analyzed for metals,
samples are compared to the highest background concentrations for each analyte from surface background sample
MexCry-SSBG-01-092922 which is the nearest background sample to the AOC (Refs. 196, pp.6,20; 203,
pp.6,22). All Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g.
(Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174). The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS. Ra 226 analysis was performed by
ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Refs. 197, pp. 6,27,31; 204,
pp.6,30).
Table 63. Sample Description and Analytical Results lor AOC 47
Sample 11)
Sa in pie
Depth
Soil
Type'
Laboratory
Sample 1D
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
Background Sample (Background - MexCry BG-01)
MexCry-
SSBG-01-
092922
0-6"
Silty
sand
596526001
9/29/22
Arsenic
(mg/kg)
0.829 BN
0.96
213, pp.
22, 28, 35
MexCry-
SSBG-01-
092922
0-6"
Silty
sand
596526001
9/29/22
Uranium
(mg/kg)
0.408 *
0.039
213, pp.
22, 28, 35
Upper-limit range of regional background
Radium-
226 (pCi/g)
2.23
NA
213, pp.
21, 843,
859
AOC Samples - Nakai Chee Begay Mine Waste Pile
199-
SSW02-
01-
092922
0-6"
Waste
rock
sand
596484006
9/29/22
Arsenic
(mg/kg)
12.2
0.99
213, pp.
19, 1556,
1579
199-
SSW02-
0-6"
Waste
rock
sand
596484006
9/29/22
Uranium
(mg/kg)
38.4
0.039
213, pp.
19, 1556,
1579
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Tnhle 63. Siimplo Description ;inil An;ilytic;il Results lor AOC 47
Siimple 11)
Ssimple
Depth
Soil
Type1
l.iihomtory
Ssimple 11)
l):itc
1 hi/iirdous
Substance
1 l;i/:iriloiis
Substance
Cone.
Report in Si
Limit2
Reference
01-
092922
199-
SSW02-
01-
092922
0-6"
Waste
rock
sand
596507006
9/29/22
Radium-
226 (pCi/g)
23.5
NA
213, pp.
19,2147,
2168
* A quality control analyte recovery is outside of the specified acceptance criteria.
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
B Either the analyte was detected in the associated blank or MDL/IDL < sample value < PQL.
N The matrix spike sample recovery is not within the specified control limits.
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 48
Name of AOC: Tom Joe No. 6 Waste Pile
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 16
AOC 48 comprises one waste pile: Tom Joe No. 6 Waste Pile. Tom Joe No. 6 Mine was operated by James W.
Hall in 1963. While operational, the mine had a total reported production volume of 29 tons (Ref. 179, p.5). The
waste generated is a result of mine operations in ore bodies within the Salt Wash Member of the Lower Morrison
Formation (Ref. 213, p.l). Surficial contamination documented in the AOC sample results below shows that the
waste pile does not have a continuous cover of 2 feet or greater.
All waste samples are surface samples from the waste pile. Observed contamination is established by analytical
significance as compared to background levels (Ref. 1, p. 14). For surface waste samples analyzed for metals,
samples are compared to the highest background concentrations for each analyte from surface background sample
MexCry-SSBG-01-092922 which is the nearest background sample to the AOC (Refs. 196, pp.6,20; 203,
pp.6,22). All Ra-226 results for this AOC exceed the upper-limit range of regional background of 2.23 pCi/g.
(Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174). The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS. Ra 226 analysis was performed by
ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Refs. 194, pp. 6,32; 202,
pp.6,21).
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Table 64. Sample Description
and Analytical Results lor AOC 4S
Sample
Sample
Soil
Laboratory
Date
1 la/arilous
1 la/arilous
Reporting
Reference
II)
Depth
Type'
Sample 11)
Substance
Substance
Cone.
Limit2
Background Sample (Background - MexCry BG-01)
MexCry-
0-6"
Silty
596526001
9/29/22
Arsenic
0.829 BN
0.96
213, pp.
SSBG-01-
sand
(mg/kg)
22, 28, 35
092922
MexCry-
0-6"
Silty
596526001
9/29/22
Lead
4.570
0.39
213, pp.
SSBG-01-
sand
(mg/kg)
22, 28 ,35
092922
MexCry-
0-6"
Silty
596526001
9/29/22
Uranium
0.408*
0.039
213, pp.
SSBG-01-
sand
(mg/kg)
22, 35, 42
092922
Upper-limit range of regional background
Radium-
226 (pCi/g)
2.23
NA
200, pp.
2,3
AOC Samples - Tom Joe No. 6 Waste Pile
427-
0-6"
Waste
596484007
9/29/22
Arsenic
22
1.0
213, pp.
SSW01-
rock
(mg/kg)
19, 1556,
01-
sand
1581
092922
427-
0-6"
Waste
596484007
9/29/22
Lead
38.5
0.41
213, pp.
SSW01-
rock
(mg/kg)
19, 1556,
01-
sand
1581
092922
427-
0-6"
Waste
596484007
9/29/22
Uranium
1,480
0.82
213, pp.
SSW01-
rock
(mg/kg)
19, 1556,
01-
sand
1581
092922
427-
0-6"
Waste
596524001
9/29/22
Radium-
345
NA
213,
SSW01-
rock
226 (pCi/g)
pp.20,
02-
sand
4087,
092922
4102
* A quality control analyte recovery is outside of the specified acceptance criteria.
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, pp. 2-47).
B Either the analyte was detected in the associated blank or MDL/IDL < sample value < PQL.
N The matrix spike sample recovery is not within the specified control limits.
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
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Areas of Observed Contamination 49 to 51 - Cove Transfer Station
The Cove Transfer Station (CTS) area includes three AOCs.
Table (>5. Co\e Transfer Station AOCs
AOC
No.
AOC Type
Mine/Claim Names
RSE Waste Pile Names
49
Contam. Soil
Cove Day School
Not Applicable
50
Contam. Soil
CTS Residence 1
Not Applicable
51
Pile
Cove Transfer Station 2
CTS2 Stockpile
The transfer stations were mining operation field camps and uranium ore storage and transfer facilities. CTS
South is an extension of CTS (Ref. 40, p.28). CTS and CTS South began operation in 1952 when Kerr-McGee
began mining operations in the nearby Lukachukai Mountains. Operations associated with CTS ceased by 1968.
The former field camp area included miner housing, an administrative structure, and vehicle maintenance
facilities (Ref. 40, p.28). The Cove Day School is adjacent to CTS South across Indian Route 33 (Ref. 40, p.23).
Ore mined within the Lukachukai Mountains was stockpiled at CTS before it was transported to the Shiprock Mill
(Ref. 40, p.28). Two residences are now located within the former CTS area, and one residence meets the
definition of a resident individual (Ref. 45, p.27).
In 2012, the USEPA Region 9 Emergency Response Section conducted an interim removal action at CTS and
CTS South. Waste material from these two areas was transported to and combined with existing waste at CTS 2 to
create a stockpile. Before the removal action, CTS 2 also operated as a transfer facility for mine material from the
Lukachukai Mountains (Ref. 44, pp. 12,13,26).
One residential property on the CTS AOC meets the definition of a resident individual because a post-removal
surface soil sample meeting the observed contamination criteria is on the residential property and within 200 feet
of the residence.
BSA-6 and BSA-7 were selected as the most appropriate background locations for AOCs 49, 50, and 51 because
they are within the same geologic unit and host similar soil types as those at AOCs (Ref. 43, pp. 45,46,627,731).
The highest background concentration for each metals analyte in either BSA-6 or -7 was used as the metals
background level for AOCs 49, 50, and 51 (Ref. 43, pp.653,757). The highest Ra-226 mean plus two standard
deviations from either BSA-6 or -7 was used as the Ra-226 background level for AOCs 49, 50, and 51 (Ref. 43,
pp.650,760).
Number by which this AOC is to be identified: 49
Name of AOC: Cove Day School
AOC Type: Contaminated Soil
Location and description of AOC (with reference to a map of the area): Figure 17
AOC 49 comprises three contaminated soil samples collected from the Cove Day School property in 2022 and
located within 200 feet of regularly used school buildings and playgrounds. Soil contamination is not inferred
between sample locations since there are paved areas and the deposition is likely not widespread as confirmed by
area-wide gamma scanning. The Cove Day School is approximately 50 feet from the CTS South removal action
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excavation zone (Ref. 44, pp. 10,26). The Cove Day School was in operation during the time that mining occurred,
and portions of the school property were used by ore haul trucks as a waiting area while other trucks unloaded at
the transfer station across the street. Ore rocks were unique on an otherwise sandy schoolyard, so they may also
have been moved around by children or others over the years.
In 2018, the Bureau of Indian Education investigated radiation levels in soil at the Cove Day School in
preparation for the future construction of a new school. Gamma scanning of the schoolyard identified five areas of
elevated gamma radiation with background levels in between (Ref. 74, pp.12-18,20). In 2022, USEPA collected
four samples of what appeared to be ore rocks from these elevated gamma areas; three of these samples were
greater than three times the background concentrations (Ref. 73, pp. 8,9).
Observed contamination is established by analytical significance as compared to background levels (Ref. 1, p. 14).
All samples are surface soil samples from on the school property. Surface soil samples analyzed for metals are
compared to the highest background concentrations for each analyte from surface background samples within an
unimpacted background area near the AOC (Refs. 40, p.37; 43, pp.650,754). For Ra-226, observed contamination
is established when the Ra-226 concentration is two standard deviations above the mean site-specific Ra-226
background concentration (Refs. 1, pp. 14,116; 200, pp. 1-2). All Ra-226 results for this AOC also exceed the
upper-limit range of regional background of 2.23 pCi/g. (Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-
174).
Soil samples comprising this AOC are impacted by mineralized rock, characteristic of ore from the Lukachukai
Mountains (Ref. 73, pp. 42, 44, 45). No natural sources of this mineralized rock are present in the Cove Valley
where the school is located (Ref. 43, pp. 630,633,634,734,737,738). Over decades since the mineralized ore rock
was deposited in the school yard, natural and anthropogenic break-down of the rock resulted in soils around the
rock becoming contaminated and taking on soil characteristics dissimilar from native soils. Therefore, background
soil samples from BSA-6 and BSA-7 are expected to differ from contaminated soils on the school yard because of
the deterioration of non-native ore rock at AOC sample locations. The metals analysis was performed by ALS
Environmental Laboratories using USEPA method SW-846 6020A ICP-MS. Ra-226 analysis was performed by
ALS Environmental Laboratories using USEPA method 901.1 gamma spectroscopy (Ref. 174, p.22).
Table 66. Sample Description itncl Analytical Results lor AOC 49
Sample
II)
Sample
Depth
Soil
Type
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit1
Reference
Background Samp
e (BSA 6)
40, p.37;
43, p.650
B6-
SS07-
01-
052218
0-6"
Sandy
loam
1805582-8
5/22/18
Lead
(mg/kg)
14
0.2
43, p.
6825; 141,
pp. 5, 33;
220, p. 72
Background Samp
e (BSA 7)
40, p.37;
43, p.754
B7-
SS19-
01-
052218
0-6"
Sandy
loam
1805587-7
5/22/18
Uranium
(mg/kg)
1.7
0.011
43,
p.6834;
142,
pp.5,31;
220, p.97
BSA-7
0-6"
Sandy
loam
1805586
5/22/18
Radium-
226 (pCi/g)
2.49*
NA
43,
p.6834;
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Table 66. Sample Description
and Analytical Results I'o
• AOC 49
S;t m pic
Sample
Soil
Laboratory
Date
1 la/ardous
1 la/ardous
Reporting
Reference
II)
Depth
Type
Sample 11)
Substance
Substance
Cone.
Limit1
200, p. 1;
142, p.9;
220, p.90
AOC Samples - Cove Day Sc
100I Contaminated Soil
472-
0-3"
Minerali
2207534-7
7/20/22
Lead
710
200
73, p. 42;
SSW06-
zed ore
(mg/kg)
174, pp. 4,
01-
rock soil
21
072022
472-
0-3"
Minerali
2207534-7
7/20/22
Uranium
31,000
20
73, p. 42;
SSW06-
zed ore
(mg/kg)
174, pp. 4,
01-
rock soil
21
072022
472-
0-3"
Minerali
2207535-7
7/20/22
Radium-
2,230
NA
73, p. 42;
SSW06-
zed ore
226 (pCi/g)
(22,300 J,
184, pp.
01-
rock soil
M3,G)
6,30
072022
472-
0-3"
Minerali
2207534-11
7/20/22
Lead
43
0.2
73, p. 44;
SSW10-
01-
zed ore
rock soil
(mg/kg)
174, pp. 4,
29
072022
472-
0-3"
Minerali
2207534-11
7/20/22
Uranium
2,400
2
73, p. 44;
SSW10-
01-
zed ore
rock soil
(mg/kg)
174, pp. 4,
29
072022
472-
0-3"
Minerali
2207535-11
7/20/22
Radium-
1,060 M3
NA
73, p. 44;
SSW10-
zed ore
226 (pCi/g)
184, pp. 6,
01-
rock soil
38;
072022
472-
0-3"
Minerali
2207534-13
7/20/22
Uranium
6,600
2
73, p. 45;
SSW12-
zed ore
(mg/kg)
174,
01-
rock soil
p.4,33
072022
472-
0-3"
Minerali
2207535-13
7/20/22
Radium-
3,770 M3
NA
73, p. 45;
SSW12-
zed ore
226 (pCi/g)
184,
01-
rock soil
p.6,44
072022
1 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
G Sample density differs by more than 15% of laboratory control sample density.
J The analyte was detected at the reported concentration; the quantitation is an estimate. As a result, the
concentration of this qualified data has been adjusted (Ref. 48, p.7, 8).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC.
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
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Number by which this AOC is to be identified: 50
Name of AOC: Cove Transfer Station - Residence 1
AOC Type: Contaminated Soil
Location and description of AOC (with reference to a map of the area): Figure 17
AOC 50 comprises an area of residual contaminated soil on residential lease land and within 200 feet of a
residence. Residence 1 is located on the north portion of CTS, and the homesite lease area is approximately
1,600 square feet (Ref. 44, p.72). An unpaved road for residence access is located east of the property. To the west
of CTS is Indian Route 33 (Refs. 44, p.71; 45, p.9).
Observed contamination is established by analytical significance as compared to background levels (Ref. 1, p. 14).
All samples are surface soil samples from Residence 1, and sample 472-SSW04-01-072022 is located within
200 feet of the residential structure. For surface soil samples analyzed for metals, soil samples are compared to the
highest background concentrations for each analyte from surface background samples near the AOC (Refs. 40,
p.37; 43, p.754). For Ra-226, observed contamination is established when the Ra-226 concentration is two
standard deviations above the mean site-specific Ra-226 background concentration (Refs. 1, pp.14,116; 200, pp.
1-2). All Ra-226 results for this AOC also exceed the upper-limit range of regional background of 2.23 pCi/g.
(Refs. 1, pp. 14,116; 200, pp. 2,3; 221, p.25; 222, pp. 171-174).
Soil samples comprising this AOC are impacted by mineralized rock, characteristic of ore from the Lukachukai
Mountains (Ref. 73, pp. 42,44,45,2153). No natural sources of this mineralized rock are present in the Cove
Valley where Residence 1 is located (Ref. 43, pp. 630,633,634,734,737,738). Over decades since the mineralized
ore rock was deposited at the Cove Transfer Station (location of Residence 1), natural and anthropogenic break-
down of the rock resulted in soils around the rock becoming contaminated and taking on soil characteristics
dissimilar from native soils. Therefore, background soil samples from BSA-6 and BSA-7 are expected to differ
from contaminated soils on Residence 1 because of the deterioration of non-native ore rock at AOC sample
locations. The metals analysis was performed by ALS Environmental Laboratories using USEPA method SW-846
6020A ICP-MS. Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA method
901.1 gamma spectroscopy (Ref. 174, p.18).
Table 67. Sample Description and Analytical Results lor AOC 50
Sample
II)
Sain pic
Depth
Soil
Type
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Report in»
Limit1
Reference
Background Sample (BSA 7)
40, p.37;
43, p.754
B7-
SS19-01-
052218
0-6"
Sandy
loam
1805587-7
5/22/18
Uranium
(mg/kg)
1.7
0.011
43,
p.6834;
142, pp. 5,
31; 220,
p. 97
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BSA-7
0-6"
Sandy
loam
1805586
5/22/18
Radium-
226 (pCi/g)
2.49*
NA
43,
p.6834;
200, p.l;
142, p.9;
220, p.90
AOC Sample - CTS/TS1 Residence 1 Contaminated Soil
472-
SSW04-
01-
072022
0-3"
Minerali
zed ore
rock soil
2207534-5
7/20/22
Uranium
(mg/kg)
10(100 J)
0.021
73, p.
2153;
174, pp. 4,
17
472-
SSW04-
01-
072022
0-3"
Minerali
zed ore
rock soil
2207535-5
7/20/22
Radium-
226 (pCi/g)
116M3
NA
73, p.
2153;
184, pp. 6,
26;
T9-
XS61-
01-
042518
0-3"
Waste
rock
sand
1805036-18
4/25/18
Uranium
(mg/kg)
13
0.0097
139, pp.5,
52;
T9-
XS93-
01-
042518
0-3"
Waste
rock
sand
1805036-20
4/25/18
Uranium
(mg/kg)
11
0.01
139,
pp.5,56;
The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
J The analyte was detected at the reported concentration; the quantitation is an estimate. As a result, the
concentration of this qualified data has been adjusted (Ref. 48, p.7, 8).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC.
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
Number by which this AOC is to be identified: 51
Name of AOC: Cove Transfer Station 2 Stockpile
AOC Type: Pile
Location and description of AOC (with reference to a map of the area): Figure 17
AOC 51 is located west of Indian Route 33 and 2.2 miles north of the Cove Day School (Ref. 44, p.71). CTS 2
was used as a stockpile for the waste removed from CTS, CTS South, and CTS 2 as part of the removal action in
2012 (Ref. 44, p. 12). In 2012, excavated material from CTS and CTS South was transported and combined with
material at CTS 2 to create an aboveground stockpile (Ref. 44, p.29).
Observed contamination is established by analytical significance as compared to background levels (Ref. 1, p. 14).
All waste samples are surface samples from the waste pile. For waste samples analyzed for metals, samples are
HRS Documentation Record
149
Lukachukai Mountains Mining District
NNN000920223
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compared to the highest background concentrations for each analyte from surface background samples near the
AOC (Refs. 40, p.37; 43, pp.650,754). For Ra-226, observed contamination is established when the Ra-226
concentration is two standard deviations above the mean site-specific Ra-226 background concentration (Refs. 1,
pp. 14,116; 200, pp. 1-2; 222, pp. 171-174). All Ra-226 results for this AOC also exceed the upper-limit range of
regional background of 2.23 pCi/g. (Refs. 1, pp.14,116; 200, pp. 2,3; 221, p.25; 222, pp.171-174). The metals
analysis was performed by ALS Environmental Laboratories using USEPA method SW-846 6020A ICP-MS.
Ra-226 analysis was performed by ALS Environmental Laboratories using USEPA method 901.1 gamma
spectroscopy (Ref. 174, p.10,16).
Table 6
-------
Table OS. Sample Description and Analytical Results lor AOC 51
Sample
II)
Sample
Depth
Soil
Type1
Laboratory
Sample 11)
Date
1 la/arilous
Substance
1 la/arilous
Substance
Cone.
Reporting
Limit2
Reference
472-
SSW01-
01-
071822
U-3"
Ore
rock
sand
22U7534-1
7.18.22
Lead
(mg/kg)
54
U.2
174, pp. 4,
9;
472-
SSW01-
01-
071822
0-3"
Ore
rock
sand
2207534-1
7/18/22
Uranium
(mg/kg)
4,600
2
174, pp. 4,
9;
472-
SSW01-
01-
071822
0-3"
Ore
rock
sand
2207535-1
7/18/22
Radium-226
(pCi/g)
1,010 M3
NA
184, pp. 6,
18;
472-
SSW02-
01-
071822
0-3"
Sandy
loam
2207534-2
7/18/22
Uranium
(mg/kg)
8.3 (83 J)
0.021
174,
pp.4,11;
472-
SSW02-
01-
071822
0-3"
Sandy
loam
2207535-2
7/18/22
Radium-226
(pCi/g)
62.1
NA
184,
pp.6,20;
1 Waste samples from the mine waste piles are compared to soil near the site to establish observed
contamination criteria and may differ somewhat than the background soil type (Ref. 211, p. 4).
2 The reporting limit is equivalent to the sample quantitation limit as defined by HRS, Section 1.1.,
Definitions. (Refs. 1, Section 1.1.; 25, p. 2-47).
* This value represents the concentration that is two standard deviations above the mean for radium-226
samples from the background study area (Ref. 200).
J The analyte was detected at the reported concentration; the quantitation is an estimate. As a result, the
concentration of this qualified data has been adjusted (Ref. 48, p.7, 8).
M3 The requested minimum detectable concentration (MDC) was not met, but the reported activity is greater
than the reported MDC. Data are usable as is because the result is above the MDC.
NA Reporting limit is not required for determining observed contamination for naturally occurring
radionuclides (Ref. 1, pp.116).
AOC Hazardous Waste Quantity
Hazardous Constituent Quantity:
The hazardous constituent quantity for the AOCs could not be adequately determined according to the HRS
requirements; that is, the total mass of all Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA) hazardous substances in the AOCs is not known and cannot be estimated with reasonable
confidence (Ref. 1, Section 2.4.2.1.1). Contaminant concentrations are not uniform throughout the AOCs and
insufficient historical and current data (manifests, potentially responsible party [PRP] records, state records,
permits, waste concentration data, etc.) are available to adequately calculate the total or partial mass of all
CERCLA hazardous substances associated with the AOCs. Therefore, there is insufficient information to
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calculate a total or partial hazardous constituent quantity for the AOCs with reasonable confidence. Scoring
proceeds to the evaluation of Tier B, hazardous waste stream quantity (Ref. 1, Section 2.4.2.1.1).
Hazardous Constituent Quantity Assigned Value: Not Scored
Hazardous Constituent Quantity Complete? No
Hazardous Wastestream Quantity:
The total hazardous wastestream quantity for the AOCs could not be adequately determined according to the HRS
requirements; that is, the total mass of all hazardous wastestreams and CERCLA pollutants and contaminants in
the AOCs is not known and cannot be estimated with reasonable confidence (Ref. 1, Section 2.4.2.1.2).
Contaminant concentrations are not uniform throughout the AOCs and insufficient historical and current data
(manifests, PRP records, State records, permits, waste concentration data, annual reports, etc.) are available to
adequately calculate the total mass of all hazardous wastestreams and CERCLA pollutants and contaminants in
the AOCs. Therefore, there is insufficient information to adequately calculate the total or partial mass of the
wastestream in the AOCs. Therefore, there is insufficient information to evaluate the hazardous wastestream
quantity for the AOCs with reasonable confidence. Scoring proceeds to the evaluation of Tier C, Volume (Ref. 1,
Section 2.4.2.1.2, Table 5-2).
Hazardous Wastestream Quantity Assigned Value: Not Scored
Hazardous Wastestream Quantity Complete? No
- Volume:
Description
The volume measure cannot be used for AOC types Contaminated Soil or Waste Pile (Ref. 1, Section 5.1.1.2.2,
Table 5-2).
Equation for Assigning Value (Ref. 1, Table 5-2): Not Determined
Volume Assigned Value: 0
- Area:
The RSE Work Plan and report for the Northern Agency Tronox Mines investigation provide descriptions of the
process for mapping the aerial extent of technically enhanced naturally occurring radioactive material (TENORM)
features at the LMMD, including the waste piles scored as AOCs (Refs. 62, pp. 68,69; 221, pp. 96,97). The
process involved mapping and inventory of mining- or reclamation-related impacts including all waste piles and
burial cells (Refs. 62, pp. 68,69; 221, pp. 96,97). Mapping consisted of confirming and recording geospatial
locations and areas of waste piles and burial cells by use of handheld Trimble Geo 7XH Global Positioning
System (GPS) units with sub-foot accuracy after postprocessing. Results were recorded in a geodatabase of
features and reported in maps within mine specific RSE Reports (Ref. 62, pp. 68,69). Boundaries of waste piles
and burial cells were refined using data from a baseline analysis of light detection and ranging (LiDAR) data and
other aerial extent data sources (Ref. 62, p. 56). Surface extent of waste piles and burial cells were captured in the
geodatabase and are presented in the AOC measurements in the table below (Refs. 62, pp. 68,69; 221, pp. 96,97).
Below is a summary of the areas and calculated assigned values for each AOC with source type "pile". Per HRS
Table 5-2 the area of a pile in square feet is divided by 34 to obtain its assigned value.
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Table 69. Summary of Area Values for Pile AOCs
AOC
Waste Description
Source
Area (ft2)
Assigned
References
No.
Type
Value*
1
Mesa I Mine 10 Waste Pile M3
Pile
17,468
513.77
3, pp.132,133
2
Mesa I Mine 11 Waste Pile M4
Pile
49,206
1,447.24
4, pp.133,134
Mesa I Mine 11 Burial Cell 9
Pile
16,393
482.14
4, pp.133, 134
3
Mesa I Mine 12 Waste Pile M5A
Pile
24,524
721.30
5, pp.135,136
Mesa I Mine 12 Waste Pile M5B
Pile
85,255
2,507.51
5, pp.135,136
Mesa I Mine 12 Waste Pile M5C
Pile
14,801
435.31
5, pp.135,136
4
Mesa I Mine 13 Waste Pile M6
Pile
103,598
3,047.01
6, pp.132,133
5
Mesa I Mine 14 Waste Pile M7A
Pile
40,577
1,193.43
7, pp.134-136
Mesa I Mine 14 Waste Pile M7B
Pile
43,705
1,285.45
7, pp.134-136
Mesa I Mine 14 Waste Pile M7C
Pile
3,807
111.97
7, pp.134-136
6
Mesa I Mine 15 Waste Pile M8A
Pile
998
1,657.09
8, pp.134-136
Mesa I Mine 15 Waste Pile M8B
Pile
56,341
29.35
8, pp.134-136
Mesa I Mine 15 Burial Cell 6a
Pile
2,939
86.45
8, pp.134-136
Mesa I Mine 15 Burial Cell 6b
Pile
1,068
31.41
8, pp.134-136
Mesa I Mine 15 Burial Cell 7
Pile
933
27.44
8, pp.134-136
7
Mesa I Camp Burial Cell 310AB
Pile
34,577
1,016.98
41, pp.132,133
Mesa I Camp Waste Pile T17A
Pile
3,172
93.29
41, pp.132,133
Mesa I Camp Waste Pile T17B
Pile
1,033
30.38
41, pp.132,133
8
Mesa 11/4 Mine Waste Pile M9
Pile
33,082
972.99
9, pp.128,129
9
Mesa 11/2 Mine Waste Pile Ml OA
Pile
37,684
1,108.35
10, pp.127,128
Mesa 11/2 Mine Waste Pile Ml OB
Pile
2,364
69.52
10, pp.127,128
10
Mesa I 1/2 West Mine Waste Pile M12
Pile
5,420
159.41
12, pp.126,127
11
Mesa I 3/4 Incline Waste Pile M25
Pile
10,660
313.53
25, pp.131,132
Mesa I 3/4 Incline Burial Cell 31a
Pile
1,420
41.77
25, pp.131,132
Mesa I 3/4 Incline Burial Cell 3 lb
Pile
11,153
328.03
12
Mesa II, Mine No. 1, P-150 Waste Pile
M28
Pile
39,028
1,147.87
28, pp.128,129
Mesa II, Mine No. 1 & 2, P-21 Waste
Pile
19,752
580.93
27, pp.132,133
Pile M27
Mesa II, Mine No. 1 & 2, P-21 Burial
Pile
75,147
2,210.20
27, pp.132,133
Cell 39
Mesa I 3/4, Mine No. 2, PI50
Unknown but >0
>0
13
Mesa II, Mine 4 Waste Pile M29A
Pile
12,796
376.34
29, pp. 127,128
Mesa II, Mine 4 Waste Pile M29B
Pile
5,432
159.75
29, pp. 127,128
Mesa II, Mine 4 Burial Cell 43
Pile
4,203
123.63
29, pp. 127,128
14
Mesa II Pit Waste Pile M24
Pile
73,721
2,168.25
24, pp.131,132
Mesa II Pit Burial Cell 44
Pile
2,951
86.81
24, pp.131,132
15
Mesa II 1/4 Mine Waste Pile CO-
07 NNWP01
Pile
871
25.62
82, pp.23,38
Mesa II 1/4 Mine Waste Pile CO-
Pile
871
25.62
82, pp.23,38
07 NNWP02
16
Henry Phillips Mine Waste Pile Mil
Pile
29,364
863.63
11, pp.125,126
17
Billy Topaha Mine Waste Pile CO-
03 CAWP01
Pile
436
12.82
83, pp.23,41
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Table 69. Summary of Area Values for Pile AOCs
AOC
No.
Waste Description
Source
Type
Area (ft2)
Assigned
Value*
References
18
Mesa II 1/2 Mine 10 Waste Pile M30
Pile
56,832
1,671.53
30, pp.131,132
Mesa II 1/2 Mine 10 Burial Cell 48
Pile
9,965
293.08
30, pp.131,132
19
Mesa II 1/2 Mine 4 Waste Pile M31
Pile
9,367
275.50
31,pp.131,132
Mesa III Mine Waste Pile M32
Pile
33,950
998.53
32, pp.133,134
20
Mesa III, Northwest Mine Waste Pile
CO-08-CAWP01
Pile
3,920
115.29
80, pp.21,36
21
Mesa III, West Mine Waste Pile CO-09-
NNWP01
Pile
11,906
350.18
81, pp.21,39
22
Mesa IV, Mine No. 1
Waste Pile M20A
Pile
72,712
2,138.60
20, pp.134-136
Mesa IV, Mine No. 1
Burial Cell 56
Pile
16,075
472.78
20, pp.134-136
Mesa IV, Mine No. 1 Waste Pile M20B
Pile
47,492
1,396.82
20, pp.134-136
Mesa IV, Mine No. 3 Waste Pile M22A
Pile
17,141
504.15
22, pp.128, 129
Mesa IV, Mine No. 3
Waste Pile M22B
Pile
7,785
228.97
22, pp.128, 129
Mesa IV, Mine No. 3
Waste Pile M22C
Pile
13,436
395.16
22, pp.128, 129
23
Mesa IV, Mine No. 2
Waste Pile M21A
Pile
16,872
496.25
21, pp.134-136
Mesa IV, Mine No. 2
Waste Pile M21B
Pile
9,636
283.41
21, pp.134-136
Mesa IV, Mine No. 2
Waste Pile M21C
Pile
2,666
78.41
21, pp.134-136
Mesa IV, Mine No. 2
Waste Pile M21D
Pile
14,718
432.89
21, pp.134-136
Mesa IV, Mine No. 2
Waste Pile M21E
Pile
2,515
73.96
21, pp.134-136
Mesa IV, Mine No. 2
Waste Pile M21F
Pile
54,050
1,589.70
21, pp.134-136
Mesa IV, Mine No. 2
Burial Cell 63
Pile
14,490
426.18
21, pp.134-136
24
Mesa IV, West Mine
Waste Pile M23
Pile
19,549
574.98
23, pp.130, 131
Mesa IV, West Mine
Burial Cell 70b
Pile
2,033
59.78
23, pp.130, 131
25
Mesa IV 1/4 Mine Waste Pile CO-
10 NNWP01
Pile
14,593
429.21
79, pp.21, 38
26
South Portal Frank No. 1 Mine
Waste Pile CO-05 NNWP14
Pile
10,237
301.09
76, pp.43,86
South Portal Frank No. 1 Mine
Waste Pile CO-05 NNWP15
Pile
10,237
301.09
76, pp.43,86
South Portal Frank No. 1 Mine
Waste Pile CO-05 NNWP16
Pile
10,237
301.09
76, pp.43,86
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Table 69. Summary of Area Values for Pile AOCs
AOC
No.
Waste Description
Source
Type
Area (ft2)
Assigned
Value*
References
South Portal Frank No. 1 Mine
Waste Pile CO-05-NNWP18
Pile
29,621
871.21
76, pp.43,86
South Portal Frank No. 1 Mine
Waste Pile CO-05 NNWP 17 and Waste
Pile CO-05 NNWP 19
Pile
13,649
401.44
76, pp.43,86
East Portal Frank No. 1 Mine
Waste Pile CO-05 NNWP05
Pile
2,287
67.26
76, pp.42,85
East Portal Frank No. 1 Mine
Waste Pile CO-05 NNWP06, Waste
Pile CO-05 NNWP08, Waste Pile CO-
05 NNWP09, and Waste Pile CO-
05 NNWP10
Pile
47,481
1,396.50
76, pp.42,85
East Portal Frank No. 1 Mine
Waste Pile CO-05 NNWP07 and Waste
Pile CO-05 NNWP 11
Pile
15,173
446.26
76, pp.42,85
East Portal Frank No. 1 Mine
Waste Pile CO-05 NNWP12
Pile
3,287
96.68
76, pp.42,85
East Portal Frank No. 1 Mine
Waste Pile CO-05 NNWP 13
Pile
9,148
269.06
76, pp.42,85
North Portal Frank No. 1 Mine
Waste Pile CO-05 NNWP01 and Waste
Pile CO-05 NNWP04
Pile
10,019
294.68
76, pp.41,84
North Portal Frank No. 1 Mine
Waste Pile CO-05 NNWP02
Pile
6,098
179.35
76, pp.41,84
North Portal Frank No. 1 Mine
Waste Pile CO-05 NNWP03
Pile
11,543
339.50
76, pp.41,84
Frank No. 2 Mine Waste Pile CO-
06 NNWP01
Pile
9,583
281.85
77, pp.23,37
Mesa IV 1/2 Mine and Simpson 181
Waste Pile M19
Pile
22,268
654.96
19, pp.131, 132
Mesa IV 1/2 Mine and Simpson 181
Burial Cell 86b
Pile
8,104
238.37
19, pp.131, 132
Mesa V Mine - 508 Waste Pile M18
Pile
6,144
180.72
18, pp.130, 131
Mesa V Mine - 508 Burial Cell 87a
Pile
14,261
419.43
18, pp.130, 131
27
NA-0316 Waste Pile CO-11 NNWP01
Pile
2,614
76.88
78, pp.24,38
NA-0316 Waste Pile CO-11 NNWP02
Pile
20,582
605.35
78, pp.24,38
NA-0316 Waste Pile CO-11 NNWP03
Pile
7,696
226.35
78, pp.24,38
28
Mesa IV, Cov087
Pile
Unknown but >0
0
29
Mesa V Mine - 103 Waste Pile M17
Pile
62,898
1,849.95
17, pp.141,142
Mesa V Adit Waste Pile M16A
Pile
45,916
1,350.47
16, pp.131,132
Mesa V Adit Burial Cell 91
Pile
2,789
82.03
16, pp.131,132
Mesa V Adit Waste Pile M16B
Pile
29,374
863.95
16, pp.131,132
Mesa V Adit Burial Cell 92
Pile
1,570
46.17
16, pp.131,132
Mesa V Adit Burial Cell 93
Pile
10,014
294.54
16, pp.131,132
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Table 69. Summary of Area Values for Pile AOCs
AOC
No.
Waste Description
Source
Type
Area (ft2)
Assigned
Value*
References
NA-0344B Burial Cell 344B-2
Pile
3,763
110.67
42, pp. 127,128
Mesa V Incline Waste Pile M15A
Pile
19,568
575.54
15, pp.128,129
Mesa V Incline Waste Pile M15B
Pile
6,978
205.24
15, pp.128,129
30
Mesa VI Mine Waste Pile M13A
Pile
35,329
1,039.10
13, pp.128,129
Mesa VI Mine Waste Pile M13B
Pile
10,208
300.23
13, pp.128,129
31
Cato No. 2 CO-04-NNWP01
Pile
30,492
896.82
75, pp.23,41
32
Frank Jr. Mine Waste Pile M14
Pile
49,609
1,459.08
14, pp.128,129
33
Knife Edge Mesa Mine Waste Pile M33
Pile
2,750
80.88
33, pp.127,128
34
Camp Mine Waste Pile M52
Pile
55,709
1,638.51
186, pp. 5,6
35
Cisco Mine Waste Piles M53A
Pile
37,519
1,103.51
186, pp. 5,6
Cisco Mine Waste Piles M53B
Pile
11,720
344.71
186, pp. 5,6
36
Joleo Mine Waste Pile M54
Pile
81,945
2,410.16
186, pp. 5,6
37
Flag No. 1 Mine Waste Pile M37A
Pile
31,447
924.92
37, pp.128,129
Flag No. 1 Mine Waste Pile M37B
Pile
10,633
312.72
37, pp.128,129
38
Black No. 1 Mine Waste Pile M34A
Pile
20,718
609.34
34, pp.128,129
Black No. 1 Mine Waste Pile M34B
Pile
11,556
339.87
34, pp.128,129
39
Black No. 2 Mine Waste Pile M35A
Pile
2,005
58.97
35, pp.127,128
Black No. 2 Mine Waste Pile M35B
Pile
1,780
52.37
Black No. 2 Mine Waste Pile M35C
Pile
2,218
65.24
Black No. 2 Mine, West Waste Pile
M36
Pile
7,570
222.65
36, pp.127,128
40
Step Mesa Mine Waste Pile M38
Pile
5,081
149.44
38, pp.129,130
41
Jimmie King No. 9 Mine Waste Pile
Pile
Unknown but >0
>0
42
NA-0332 Waste Pile
Pile
Unknown but >0
>0
43
NA-0333 Waste Pile
Pile
Unknown but >0
>0
44
Mexican Cry Mine - 197 Waste Pile
Pile
Unknown but >0
>0
45
Mexican Cry Mine - 198 Waste Pile
Pile
Unknown but >0
>0
46
Hall Mine Waste Pile
Pile
Unknown but >0
>0
47
Nakai Chee Begay Mine Waste Pile
Pile
Unknown but >0
>0
48
Tom Joe No. 6 Waste Pile
Pile
Unknown but >0
>0
51
Cove Transfer Station 2 Stockpile
Pile
280,781
8,258.26
Ref. 44, p.24
Sum (Pile)
>2,460,662
>72,372.41
Assigned Value is the Area in square feet divided by 34 (Ref. 1, p.80, Table 5-2)
Per the HRS, the highest of the values assigned to each area of observed contamination for hazardous
constituent quantity (Tier A), hazardous wastestream quantity (Tier B), Volume (Tier C), and Area (Tier D)
should be assigned as that area of observed contamination's hazardous waste quantity value (Ref. 1, Section
2.4.2.1.5). These assigned hazardous waste quantity values are based on the non-radioactive hazardous
substances only and do not include the radioactive substance (radium-226). There is insufficient information to
score the radioactive hazardous waste quantity values, therefore it is unknown but >0 (Ref. 1, Section 7.2.5.3,
Table 2-6).
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Below is a summary of the areas and calculated assigned hazardous waste quantity values for each AOC
with source type "contaminated soil". Per HRS Table 5-2 the area of contaminated soil in square feet is
divided by 34,000 to obtain its assigned value.
Table 70. Summary of Area Values for Contaminated Soil AOCs
AOC
No.
Waste Description
Source Type
Area (ft2)
Assigned
Value
References
49
Cove Day School
Contaminated Soil
Unknown but >0
>0
50
Cove Transfer Station
Contaminated Soil
Unknown but >0
>0
Sum (Contaminated Soil)
>0
The sum of all AOC hazardous waste quantity assigned values is >72,372.41; this sum is used to determine the
hazardous waste quantity factor value for the pathway (Ref. 1, Section 2.4.2.2, Table 2-6).
Hazardous Waste Quantity Factor Value (Ref. 1, Table 2-6): 10,000
Attribution
The LMMD site is the result of a post-World War II and Cold War uranium and vanadium mining district
operated by a series of mining companies under numerous mine claims and leases between 1949 and 1968 (Ref.
187, pp. 34-53). The LMMD site comprises 51 AOCs; 49 of which are waste piles and 2 consist of contaminated
soil. Each AOC is the direct result of uranium and vanadium ore extraction, transport, transfer, storage, and/or
migration derived from mining activities in the Lukachukai Mountains (Refs. 187, p. 5; 210). The waste is the
byproduct of mine operations in ore deposits within the Salt Wash Member of the Lower Morrison Formation (see
section 5.1.0 of this HRS documentation record). While natural in origin, the waste materials are present and
exposed at the ground surface due to mining activities.
The dominant mining methods in LMMD consisted of underground room and pillar, open stoping, incline shafts,
and vertical shafts, resulting in waste piles comprising remnant overburden, protore, and other contaminated
material (Refs. 19, p. 3; 187, p. 14, 15). The waste piles were created from the mining operation that extracted
uranium ore (Ref. 210). Numerous samples collected from the waste piles, which are present throughout the
LMMD site, have been shown to contain arsenic, lead, vanadium, and radium-226 at concentrations significantly
greater than background levels (see Figures 1-19 and section 5.1.0 of this HRS documentation record).
Lead, uranium, and radium-226 were also detected at concentrations significantly above background levels in
surface soils at the Cove Day School, and uranium and radium-226 were detected at concentrations significantly
above background levels in surface soil at a residential property (see section 5.1.0 of this HRS documentation
record). Ore mined within the Lukachukai Mountains was stockpiled at the Cove transfer station before it was
transported to the Shiprock Mill (Ref. 40, p.28). The transfer stations were mining operation field camps and
uranium ore storage and transfer facilities (ref. 210, pp.1,2,4). The Cove Day School is adjacent to CTS South,
and the residential property is now located within the former CTS area. The Cove Day School was in operation
during the time that the mining operations occurred, and portions of the school property were used by ore haul
trucks as a waiting area, likely resulting in the soil contamination, while other trucks unloaded at the transfer
station across the street. Ore rocks were unique on an otherwise sandy schoolyard, so they may also have been
moved around by children or others over the years. There are no nearby natural sources of the uranium ore
material found in the schoolyard, as the Salt Wash Member of the Lower Morrison Formation is only present in
the Lukachukai Mountains (Ref. 189, pp.10,17,18).
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No other anthropogenic origins of the hazardous substances have been identified in the area.
Hazardous Substances in the Release
Arsenic
Lead
Ra-226
Uranium
Additional hazardous substances met the AOC criteria; however, they were not included in this HRS
documentation record since the analytes did not increase the overall HRS score of the LMMD site (Ref. 62,
pp.141,142).
Other Possible Areas of Observed Contamination
Fourteen other possible areas of observed contamination are located on Cove Mesa, East Mesa, and West Mesa.
Twelve are on Cove Mesa, one is on East Mesa, and one is on West Mesa. (Ref. 214, pp. 1-9). West Mesa Mine is
in the Round Rock Chapter, and East Mesa Mine is in the Red Valley Chapter. The Cove Mesa mines are split
between the Sweetwater/Tolikan Chapter and Red Valley Chapter since the chapter border runs down the middle
of the mesa. Mines on the east side of Cove Mesa are generally in the Red Valley Chapter while mines on the
west side of Cove Mesa are in the Sweetwater/Tolikan Chapter (Ref. 57, p.2). Each of these other possible areas
of observed contamination has been sampled and found to be contaminated with the same contaminants as the
scored AOCs (see Figures 18 and 19).
Cove Mesa Mines (Cato Sells) were operated by Cato Sells under VCA from 1950 through 1965 (Ref. 56, p. 10).
Cove Mesa Mines (AEC Plot 7) were operated by VCA, Leroy Pettigrew, and William Wittmeyer from 1954
through 1961 and by VCA, C.H. Corey Jr., and William George from 1966 through 1965 (Refs. 59, p.22; 175, p.
3). East Mesa Mines were operated by Leroy Pettigrew from 1951 through 1953 and by Pettigrew and Davis from
1953 through 1955 (Ref. 58, p.5). The operator of West Mesa Mine is unknown (Ref. 57, p.5). Operations
included underground mining that tapped paleochannels in the Salt Wash Member of the Lower Morrison
Formation that are rich in uranium and vanadium. Underground mine workings exist within the Cove Mesa area.
Waste piles consist of overburden or lower grade protore discarded near or downslope of portals (Refs. 56,
pp.7,8,9; 57, p.4; 58, p.4; 59, pp.13,15,16,18,19, 20,21).
Table 71. Summary of Other Possible AOCs
Oilier Possible
AOC Names
Other Possible Areas ol'Obsened Contamination Description (kelerence)
1. Cove Mesa
Mines (Cato
Sells - 34)
Co\ c Mesa Mines (Calo Sells) arc located north of Co\ c Mesa Mines (ALC Plot 7)
(Figure 18) (Ref. 56, p.2). Sample 034-SSW01-01-100322 collected within the first 6 inches
of the surface at Cato Sells - 34 mine has concentrations of uranium at 500 milligrams per
kilogram (mg/kg) and Ra-226 at 177 picocuries per gram (pCi/g) (Refs. 196, p.38; 203,
p.31). Background sample COVE-SSBG02-01-100322 has concentrations of arsenic at
0.96 mg/kg, lead at 4.1 mg/kg, uranium at 0.60 mg/kg, and Ra-226 at 0.84 pCi/g (Refs. 196,
p.44; 203, p.34).
2. Cove Mesa
Mines (Cato
Sells - 35)
Cove Mesa Mines (Cato Sells) are located north of Cove Mesa Mines (AEC Plot 7)
(Figure 18) (Ref. 56, p.2). Sample 035-SSW01-01-100322 collected within the first 6 inches
of the surface at Cato Sells - 35 mine has concentrations of arsenic at 6.3 mg/kg, uranium at
975 mg/kg, and Ra-226 at 201 pCi/g (Refs. 196, p.34; 203, p.29). Background sample
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Table 71. Siiiniiiiirv of Other Possible AOC 's
Other Possible
AOC Names
Other Possible Areas of Observed Contamination Description (Reference)
COVE-SSBG02-01-100322 has concentrations of arsenic at 0.96 mg/kg, lead at 4.1 mg/kg,
uranium at 0.60 mg/kg, and Ra-226 at 0.84 pCi/g (Refs. 196, p.44; 203, p.34).
3. Cove Mesa
Mines (Cato
Sells - 36)
Cove Mesa Mines (Cato Sells) are located north of Cove Mesa Mines (AEC Plot 7)
(Figure 18) (Ref. 56, p.2). Samples 036-SSW01-01-100122 and 036-SSW02-01-100122
collected within the first 6 inches of the surface at Cato Sells - 36 mine have concentrations
of arsenic at 9.8 mg/kg, lead at 14 mg/kg, uranium at 146 mg/kg, and Ra-226 at 36 pCi/g
(Refs. 194, pp.54,56; 201, p.40). Background sample COVE-SSBG02-01-100322 has
concentrations of arsenic at 0.96 mg/kg, lead at 4.1 mg/kg, uranium at 0.60 mg/kg, and
Ra-226 at 0.84 pCi/g (Refs. 196, p.44; 203, p.34).
4. Cove Mesa
Mines (AEC
Plot 7-37)
Cove Mesa Mines (AEC Plot 7) are located north of East Mesa Mines (Figure 18) (Ref. 59,
p.3). Samples 037-SSW01-01-100122 and 037-SSW03-01-100122 collected within the first
6 inches of the surface at AEC Plot 7-37 mine have concentrations of arsenic at 8.0 mg/kg,
uranium at 78 mg/kg, and Ra-226 at 26 pCi/g (Refs. 194, pp.44,50; 201, p.37). Background
sample COVE-SSBG02-01-100322 has concentrations of arsenic at 0.96 mg/kg, lead at
4.1 mg/kg, uranium at 0.60 mg/kg, and Ra-226 at 0.84 pCi/g (Refs. 196, p.44; 203, p.34).
5. Cove Mesa
Mines (AEC
Plot 7-38)
Cove Mesa Mines (AEC Plot 7) are located north of East Mesa Mines (Figure 18) (Ref. 59,
p.3). Samples 038-SSW02-01-100122 and 038-SSW03-01-100122 collected within the first
6 inches of the surface at AEC Plot 7-38 mine have concentrations of uranium at
142 mg/kg, and Ra-226 at 423 pCi/g (Refs. 194, p.52; 203, p.35). Background sample
COVE-SSBG02-01-100322 has concentrations of arsenic at 0.96 mg/kg, lead at 4.1 mg/kg,
uranium at 0.60 mg/kg, and Ra-226 at 0.84 pCi/g (Refs. 196, p.44; 203, p.34).
6. Cove Mesa
Mines (AEC
Plot 7-39)
Cove Mesa Mines (AEC Plot 7) are located north of East Mesa Mines (Figure 18) (Ref. 59,
p.3). Sample 039-SSW03-01-100122 collected within the first 6 inches of the surface at AEC
Plot 7-39 mine has concentrations of arsenic at 10 mg/kg, lead at 21 mg/kg, uranium at
552 mg/kg, and Ra-226 at 155 pCi/g (Refs. 194, p.42; 201, p.33). Background sample
COVE-SSBG02-01-100322 has concentrations of arsenic at 0.96 mg/kg, lead at 4.1 mg/kg,
uranium at 0.60 mg/kg, and Ra-226 at 0.84 pCi/g (Refs. 196, p.44; 203, p.34).
7. Cove Mesa
Mines (AEC
Plot 7-430)
Cove Mesa Mines (AEC Plot 7) are located north of East Mesa Mines (Figure 18) (Ref. 59,
p.3). Samples 430-SSW03-01-100122 and 430-SSW02-01-100122 collected within the first
6 inches of the surface at AEC Plot 7-430 mine have concentrations of arsenic at 9.8 mg/kg,
uranium at 316 mg/kg, and Ra-226 at 78 pCi/g (Refs. 195, pp.52,54; 202, p.38). Background
sample COVE-SSBG02-01-100322 has concentrations of arsenic at 0.96 mg/kg, lead at
4.1 mg/kg, uranium at 0.60 mg/kg, and Ra-226 at 0.84 pCi/g (Refs. 196, p.44; 203, p.34).
8. Cove Mesa
Mines (AEC
Plot 7-431)
Cove Mesa Mines (AEC Plot 7) are located north of East Mesa Mines (Figure 18) (Ref. 59,
p.3). Sample 431-SSW01-01-100122 collected within the first 6 inches of the surface at AEC
Plot 7 - 431 mine has concentrations of uranium at 5.6 mg/kg and Ra-226 at 4.37 pCi/g
(Refs. 195, p.48; 202, p.35). Background sample COVE-SSBG02-01-100322 has
concentrations of uranium at 0.60 mg/kg, and Ra-226 at 0.84 pCi/g (Refs. 196, p.44; 203,
P.34).
9. Cove Mesa
Mines (AEC
Plot 7 - 434)
Cove Mesa Mines (AEC Plot 7) are located north of East Mesa Mines (Figure 18) (Ref. 59,
p.3). Sample 434-SSW01-01-100122 collected within the first 6 inches of the surface at AEC
Plot 7 - 434 mine has concentrations of uranium at 8.8 mg/kg and Ra-226 at 12.8 pCi/g
(Refs. 195, pp.56; 202, p.39). Background sample COVE-SSBG02-01-100322 has
concentrations of uranium at 0.60 mg/kg, and Ra-226 at 0.84 pCi/g (Refs. 196, p.44; 203,
P.34).
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Table 71. Siiiniiiiirv of Oilier Possible AOC 's
Other Possible
AOC \nines
Other Possible Areas of Observed Contamination Description (Reference)
10. Cove Mesa
Mines (AEC
Plot 7 - 497)
Cove Mesa Mines (AEC Plot 7) are located north of East Mesa Mines (Figure 18) (Ref. 59,
p.3). Samples 497-SSW03-01-093022 and 497-SSW01-01-093022 collected within the first
6 inches of the surface at AEC Plot 7 - 497 mine have concentrations of arsenic at 5.5 mg/kg,
lead at 17 mg/kg, uranium at 269 mg/kg, and Ra-226 at 63 pCi/g (Refs. 195, pp.42,38; 202,
p.32). Background sample COVE-SSBG02-01-100322 has concentrations of arsenic at
0.96 mg/kg, lead at 4.1 mg/kg, uranium at 0.60 mg/kg, and Ra-226 at 0.84 pCi/g (Refs. 196,
p.44; 203, p.34).
11. Cove Mesa
Mines (AEC
Plot 7 - 498)
Cove Mesa Mines (AEC Plot 7) are located north of East Mesa Mines (Figure 18) (Ref. 59,
p.3). Samples 498-SSW02-01-093022 and 498-SSW03-01-093022 collected within the first
6 inches of the surface at AEC Plot 7 - 498 mine have concentrations of arsenic at 16 mg/kg,
lead at 25 mg/kg, uranium at 1,490 mg/kg, and Ra-226 at 303 pCi/g (Refs. 195, p.46; 196
p.24; 202, p.34). Background sample COVE-SSBG02-01-100322 has concentrations of
arsenic at 0.96 mg/kg, lead at 4.1 mg/kg, uranium at 0.60 mg/kg, and Ra-226 at 0.84 pCi/g
(Refs. 196, p.44; 203, p.34).
12. Cove Mesa
Mines (AEC
Plot 7-501)
Cove Mesa Mines (AEC Plot 7) are located north of East Mesa Mines (Figure 18) (Ref. 59,
p.3). Samples 501-SSW03-02-100122 and 501-SSW01-01-100122 collected within the first
6 inches of the surface at AEC Plot 7-501 mine have concentrations of arsenic at 18 mg/kg,
lead at 45 mg/kg, uranium at 5,590 mg/kg, and Ra-226 at 621 pCi/g (Refs. 196, pp.32,26;
203, p.25). Background sample COVE-SSBG02-01-100322 has concentrations of arsenic at
0.96 mg/kg, lead at 4.1 mg/kg, uranium at 0.60 mg/kg, and Ra-226 at 0.84 pCi/g (Refs. 196,
p.44; 203, p.34).
13. East Mesa
Mines
East Mesa Mines are located northeast of West Mesa Mine in the Red Valley Chapter
(Figure 18) (Ref. 58, p.2). Samples 493-SSW01-01-093022 and 493-SSW04-01-093022
collected within the first 6 inches of the surface have concentrations of arsenic at 2.8 mg/kg,
lead at 18 mg/kg, uranium at 1,070 mg/kg, and Ra-226 at 368 pCi/g (Refs. 195, pp. 30,36;
202, p.29). Background sample Cove-SSBG-01-093022 has concentrations of arsenic at
0.79 mg/kg, lead at 3.8 mg/kg, uranium at 0.28 mg/kg, and Ra-226 at 0.42 pCi/g (Refs. 196,
p.22; 203, p.23).
14. West Mesa
Mine
West Mesa Mine is in the Round Rock Chapter near the Red Valley Chapter and Round
Rock Chapter border. The mine is southwest of East Mesa Mines (Figure 18) (Ref. 57, p.2).
Sample 040-SSW02-01-093 022 collected within the first 6 inches of the surface has
concentrations of arsenic at 3.9 mg/kg, lead at 31 mg/kg, uranium at 1,020 mg/kg, and
Ra-226 at 263 pCi/g (Refs. 194, p.36; 201, p.30). Background sample Cove-SSBG-01-
093022 has concentrations of arsenic at 0.79 mg/kg, lead at 3.8 mg/kg, uranium at
0.28 mg/kg, and Ra-226 at 0.42 pCi/g (Refs. 196, p.22; 203, p.23).
5.1.1 RESIDENT POPULATION THREAT
5.1.1.1 LIKELIHOOD OF EXPOSURE
Three samples comprising AOC 49 were collected from within the fence surrounding the Cove Day School. All
three samples were collected within 200 feet of the main school building. The one sample in AOC 50 that
establishes observed contamination at Residence 1 is located within 200 feet of the residential dwelling. Sample
numbers, distances, and references for this paragraph are provided in the table below. The AOC 50 sample is on
land owned by the Bureau of Indian Affairs, as is Residence 1, with no private property boundary between.
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Table 72. Resident Population AOC Samples
Sample ID
Distance of Population/Resource from
Area of Observed Contamination
References
472-SSW06-01-072022
166 feet (Cove Day School)
73, pp.42,2154
472-SSW10-01-072022
139 feet (Cove Day School)
73, p.2155
472-SSW12-01 -072022
192 feet (Cove Day School)
73, pp.45,2155
472-SSW04-01-072022
137 feet (Residence 1)
73, pp.41,2153,2157
Resident Population Threat Likelihood of
Exposure Factor Category Value: 550
5.1.1.2 WASTE CHARACTERISTICS
5.1.1.2.1 Toxicity
Table 73. Toxicity
Hazardous Substance
Toxicity Factor Value
References
Arsenic
10,000
2, P-2
Lead
10,000
2, P-5
Radium 226
10,000
2, P-8
Uranium
10,000
2, p. 11
Toxicity Factor Value: 10,000
5.1.1.2.2 Hazardous Waste Quantity
Table 74. AOC Hazardous Waste Quantity Values
AOC
Number
AOC Hazardous
Source Type
AOC Hazardous Waste Quantity
Constituent Quantity
Complete?
1
Pile
513.77
No
2
Pile
1,929.38
No
3
Pile
3,664.12
No
4
Pile
3,047.01
No
5
Pile
2,590.85
No
6
Pile
1,831.74
No
7
Pile
1,140.65
No
8
Pile
972.99
No
9
Pile
1,177.87
No
10
Pile
159.41
No
11
Pile
683.33
No
12
Pile
3,939.00
No
13
Pile
659.72
No
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Table 74. AOC Hazardous Waste Quantity Values
AOC
Number
AOC Hazardous
Source Type
AOC Hazardous Waste Quantity
Constituent Quantity
Complete?
14
Pile
2,255.06
No
15
Pile
51.24
No
16
Pile
863.63
No
17
Pile
12.82
No
18
Pile
1,964.61
No
19
Pile
1,274.03
No
20
Pile
115.29
No
21
Pile
350.18
No
22
Pile
5,136.48
No
23
Pile
3,380.80
No
24
Pile
634.76
No
25
Pile
429.21
No
26
Pile
7,040.54
No
27
Pile
908.58
No
28
Pile
Unknown but >0
No
29
Pile
5,378.56
No
30
Pile
1,339.33
No
31
Pile
896.82
No
32
Pile
1,459.08
No
33
Pile
80.88
No
34
Pile
1,638.51
No
35
Pile
1,448.22
No
36
Pile
2,410.16
No
37
Pile
1,237.64
No
38
Pile
949.21
No
39
Pile
399.23
No
40
Pile
149.44
No
41
Pile
Unknown but >0
No
42
Pile
Unknown but >0
No
43
Pile
Unknown but >0
No
44
Pile
Unknown but >0
No
45
Pile
Unknown but >0
No
46
Pile
Unknown but >0
No
47
Pile
Unknown but >0
No
48
Pile
Unknown but >0
No
49
Contaminated Soil
Unknown but >0
No
50
Contaminated Soil
Unknown but >0
No
51
Pile
8,258.26
No
Sum of Values: >72,372.41
Hazardous Waste Quantity Factor Value: 10,000
(Ref. 1, Table 2-6)
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5.1.1.2.3 Calculation of Waste Characteristics Factor Category Value
Toxicity Factor Value: 10,000
Hazardous Waste Quantity Factor Value: 10,000
Toxicity Factor Value x Hazardous Waste Quantity Factor Value: 100,000,000
Waste Characteristics Factor Category Value: 100
(Ref. 1, Table 2-7)
5.1.1.3 TARGETS
Level I Concentrations
Sample ID: 472-SW06-01-072022
AOC Number: 49
Reference for Benchmark: 2, pp. 11
Table 75. Level I Concentrations for Sample ID: 472-SW06-01-072022
Hazardous Substance
Hazardous Substance
Concentration (units)
Benchmark
Concentration
Benchmark
Uranium
31,000 mg/kg
15.6 mg/kg
Non-Cancer Risk
Sample ID: 472-SW10-01-072022
AOC Number: 49
Reference for Benchmark: 2, pp. 11
Table 76. Level I Concentrations for Sample ID: 472-SW10-01-072022
Hazardous Substance
Hazardous Substance
Concentration (units)
Benchmark
Concentration
Benchmark
Uranium
2,400 mg/kg
15.6 mg/kg
Non-Cancer Risk
Sample ID: 472-SW 12-01-072022
AOC Number: 49
Reference for Benchmark: 2, pp. 11
Table 77. Level I Concentrations for Sample ID: 472-SW12-01-072022
Hazardous Substance
Hazardous Substance
Concentration (units)
Benchmark
Concentration
Benchmark
Uranium
6,600 mg/kg
15.6 mg/kg
Non-Cancer Risk
Sample ID: 472-SSW04-01-072022
AOC Number: 50
Reference for Benchmark: 2, p. 11
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Table 78. Level I Concentrations for Sample ID: 472-SSW04-01-072022
Hazardous Substance
Hazardous Substance
Concentration (units)
Benchmark
Concentration
Benchmark
Uranium
100 mg/kg
15.6 mg/kg
Non-Cancer Risk
5.1.1.3.1 Resident Individual
AOC Numbers: 49 and 50
Level of Contamination (Level I/Level II): Level I
References: 1, Section 5.1.1.3.1; 2, pp.11,14
Resident Individual Factor Value: 50
5.1.1.3.2 Resident Population
5.1.1.3.2.1 Level I Concentrations
Level I Resident Population Targets
There are 42 students associated with the Cove Day School (AOC 49), and two residents associated with AOC 50
(Refs. 70; 73, p. 17).
Table 79. Level I Resident Population
AOC Number
Sample ID
Number of
Buildings
County
Multiplier
Population
References
49
472-SW06-01-072022
472-SW10-01-072022
472-SW12-01-072022
1
NA
42
70, p. 1; 73,
P-17
50
472-SSW04-01-072022
1
NA
2
73, p.16,
2153,2157
Sum of individuals subject to Level I concentrations: 42 (Students) + 2 Residents (at Residence 1) = 44
Sum of individuals subject to Level I concentrations x 10: 440
Level I Concentrations Factor Value: 440
5.1.1.3.2.2 Level II Concentrations
Level II Samples
There are no Level II resident individuals.
Level II Resident Population Targets
There are no Level II resident individuals.
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5.1.1.3.3 Workers
15 workers are associated with the Cove Day School (Ref 70, p. 1).
Table 80. Workers
AOC Number
Number of Workers
References
49
15
70, p. 1
Total workers: 15
Workers Factor Value: 5
(Ref. 1, Table 5-4)
5.1.1.3.4 Resources
Description of Resource(s): None
5.1.1.3.5 Terrestrial Sensitive Environments
Mexican spotted owls (strix occidentalis lucida) inhabit the canyons and mesas in the Cove Wash watershed
(Refs. 72, p. 5; 192, p. 27). Past Mexican spotted owl surveys have resulted in the creation of Protected Activity
Centers to protect the Cove Wash watershed populations (Ref. 72, p. 5). For Mexican spotted owls, the US Fish
and Wildlife Service defines PACs to include all known owl sites and all areas in mixed-conifer or pine-oak types
with slopes greater than 40 percent where timber harvest has not occurred in 20 years, and all legally and
administratively reserved lands, such as Wilderness Areas or Research Natural Areas. Protected areas can also
include steep-walled canyon habitat. Owl PACs are delineated around known owl sites. PACs include a minimum
of 600 acres (ac) (243 hectares [ha]) that includes the best nesting and roosting (i.e., resting) habitat in the area. A
PAC contains the nest site, a roost grove commonly used during the breeding season in the absence of a verified
nest site, or the best nesting/roosting habitat if both nesting and roosting information are lacking and the most
proximal and highly used foraging areas. Areas outside of PACs, including restricted areas, provide additional
habitat appropriate for foraging (Ref. 224, p. 3). See Figure 20 for location of PACs and habitat surrounding the
PACs used by MSO.
The entire Lukachukai mountains are relatively small compared to the Navajo Nation and they comprise a unique
biotic community important to the culture and lifeways of the Dine people. Dine medicine men and other tribal
members use the Lukachukai mountains to harvest numerous unique herbs and plants that grow in few other areas
across the Navajo Nation. The Lukachukai mountain biotic community of Douglas fir, ponderosa pine, pinon pine
and juniper forests and numerous deeply incised washes create habitat for medicinal and ceremonial herbs that
grow in few other areas on the Navajo Nation. The specific herbs and other plant species used by the Dine people
for ceremonial and medicinal purposes are held in confidence among tribal members, and thus specific plant
community locations are unknown, but prevalent in the Lukachukai mountains. Dine medicine men, elders, and
others travel from all over the Navajo Nation to sustainably harvest these herbs for ceremonial and medicinal
purposes (Ref. 66).
The entire Lukachukai mountains are an important terrestrial breeding area utilized for breeding by large and/or
dense aggregations of animals used culturally by the Dine people. The Lukachukai mountain biotic community of
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Douglas fir, ponderosa pine, pinon pine and juniper forests create habitat for a large and/or dense aggregation of
large vertebrate species used to sustain the Dine people. Important large vertebrate species in the Lukachukai
Mountains include populations of elk, mule deer, bear, cougar, white-tail deer, and others. Local Navajo elders
such as Cove Chapter President James Benally attest to the importance to protect the entire Lukachukai mountains
to sustain the breeding populations of these important vertebrate mammal species (Ref. 67).
Zuni fleabane (Erigeron rhizomatous) occur along, steep, barren, weathered slopes of northeast, north, west facing
escarpment of Lukachukai Mountains. Habitat for the Zuni fleabane includes steep, barren slopes in ponderosa
pine, Douglas fir, and pinyon - juniper woodland communities, specifically in the weathered Chuska Sandstone,
and upper Chinle Formation geologies. Biological surveys in the Cove Wash watershed show that Zuni fleabane
habitat occurs within the Cove Wash watershed overlapping with the AOCs (Refs. 192, pp. 22,23; 205, pp.
223,224).
Golden eagles are present throughout the Navajo Nation. The Carrizo, Chuska, and Lukachukai Mountains all
provide habitat for golden eagles. Golden eagles are known to inhabit Mexican Cry mesa and Lukachukai
Mountains. Specific habitat characteristics include isolated, laterally extensive, vertical cliff walls, remote
ponderosa pine forest, or any isolated buttes and mesas with cliff faces and ledges (Ref. 192, p. 26). These
conditions are present throughout the LMMD and at all the AOCs.
AOCs 1 through 51 are located within the boundaries of terrestrial sensitive environments (Refs. 192, pp. 21-27;
68, pp. 1-4; 62, p.63). Affected environmental targets and the AUM locations are listed in the table below.
Table 81. Terrestrial Sensitive Environments
AOC
Letter
Terrestrial Sensitive Environment
Assigned Value
(Ref. 1, Table 5-5)
References
1 to 32
Federal threatened species - Mexican spotted owl
(Strix occidentalis lucida)
75
69, p.2; 72, pp.
8,12-16,20
1 thru 48
Federal threatened species - Zuni fleabane (Cirsium
chellyense)
75
69, p.8; 192,
pp.22,23
1 thru 48
Terrestrial area used for breeding by large or dense
aggregation of vertebrate animals - elk (Cervus
elephus), mule deer (Odocoileus hemionus), American
black bear (Ursus americanus), cougar (Puma
concolor), white-tail deer (Odocoileus virginianus)
75
67
1 thru 51
State (tribal) endangered species - golden eagle
(Aquila chrysaetos)
50
68, p.2; 92, p.
26
1 thru 51
Particular area relatively small in size important to the
maintenance of a unique biotic community - the
Lukachukai Mountains is an important area for
medicinal and cultural herb collection for the Navajo
people. There are many species spread throughout
these mountains.
25
67
Likelihood of exposure factor category value (LE): 550
Waste characteristics factor category value (WC): 100
Terrestrial sensitive environments value (ES): 300
HRS Documentation Record
166
Lukachukai Mountains Mining District
NNN000920223
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Product (LE x WC x ES): 16,500,000
(LE x WC x ES)/82,500: 200
If result is >60, Value of EC = 60 x 82,500/(LE x WC): 90
Terrestrial Sensitive Environments Factor Value: 90
5.1.2 NEARBY POPULATION THREAT
The nearby population threat has not been scored.
HRS Documentation Record
167
Lukachukai Mountains Mining District
NNN000920223
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