EPA Superfund
Record of Decision:
PB98-964601
EPA 541-R98-034
September 1998
Eastern Michaud Flats
Contamination
Pocatello, ID
6/8/1998
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 10
1200 6TH AVENUE
SEATTLE, WASHINGTON
RECORD OF DECISION
DECLARATION,
DECISION SUMMARY,
AND
RESPONSIVENESS SUMMARY
FOR
EASTERN MICHAUD FLATS SUPERFUND SITE
POCATELLO, IDAHO
JUNE 1998
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PREFACE
This Record of Decision documents the remedial action plan for contaminated ground water and
associated sources and contaminated soils at the Eastern Michaud Flats Superfund site. This
Record of Decision serves three functions:
• It certifies that the remedy selection process was carried out in accordance with the
Comprehensive Environmental Response, Compensation, and Liability Act as
amended, and to the extent practicable, with the National Contingency Plan.
• It summarizes the technical parameters of the remedy, specifying the treatment,
engineering, and institutional components, as well as remediation goals.
• It provides the public with a consolidated source of information about the site, the
selected remedy, and the rationale behind the selection.
• In addition, the Record of Decision provides the framework for transition into the
next phases of the remedial process, Remedial Design and Remedial Action.
The Record of Decision consists of three basic components: a Declaration, a Decision Summary,
and a Responsiveness Summary. The Declaration functions as an abstract for the key information
contained in the Record of Decision and is signed by the U.S. Environmental Protection Agency
Regional Administrator. The Decision Summary provides an overview of the site characteristics,
the alternative evaluated, and an analysis of those options. The Decision Summary also identifies
the selected remedy and explains how the remedy fulfills statutory requirements. The
Responsiveness Summary addresses public comments received on the Proposed Plan, the
Remedial Investigation/Feasibility Study, and other information in the administrative record.
This Record of Decision is organized into three main sections: the Declaration, the Decision
Summary, and Appendices. Appendix A contains additional tables and figures; Appendix B
consists of the Responsiveness Summary; Appendix C contains the concurrence letter from the
State of Idaho; and, Appendix D contains the method used to estimate concentrations of radon in
indoor air.
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TABLE OF CONTENTS
PREFACE i
LIST OF FIGURES vii
LIST OF TABLES ix
LIST OF ACRONYMS USED IN THIS DOCUMENT x
DECLARATION FOR THE RECORD OF DECISION 1
1.0 SITE NAME, LOCATION, AND DESCRIPTION 5
1.1 Site Name and Location 5
1.2 General Site Description 5
1.2.1 Land Use 5
1.2.2 Geology and Hydrogeology 8
1.2.3 Hydrology (Surface Water) 8
1.2.4 Climate 10
1.2.5 Ecology 10
1.3 Site Subareas 10
1.3.1 FMC Plant Area ,12
1.3.2 Simplot Plant Area 12
1.3.3 Off-Plant Area 15
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 16
2.1 Historical Land Use 16
2.1.1 FMC Plant 16
2.1.2 Simplot Plant 16
2.2 Previous Studies 17
2.3 Listing on the National Priorities List 17
2.4 Company Actions to Date 17
2.4.1 Simplot 18
2.4.2 FMC 19
2.5 History of EPA Enforcement Activity 20
2.5.1 FMC Plant 20
2.5.2 Simplot Plant 21
2.5.3 Off-Plant Area 21
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 21
11
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4.0 SCOPE AND ROLE OF RESPONSE ACTION 23
4.1 Air , 23
4.2 RCRA . 24
5.0 SUMMARY OF SITE CHARACTERISTICS 25
5.1 Geologic Setting 26
5.2 Hydrogeology 26
5.3 Surface Water Hydrology 27
5.4 Climate 27
5.5 Ecosystems and Species of Concern 28
5.6 Key Remedial Investigation Findings 29
5.6.1 Soils and Solids 29
5.6.2 Ground water 30
5.6.3 Surface Water/Sediments 31
5.6.4 Air 33
5.6.5 Terrestrial and Aquatic Investigations 34
6.0 SUMMARY OF SITE RISKS 35
6.1 Human Health Risks 35
6.1.1 Approach to Human Health Risks 35
6.1.2 Conceptual Site Model 35
6.1.3 Background Concentrations 36
6.1.4 Contaminants of Potential Concern 36
6.1.5 Toxicity Assessment 38
6.1.5.1 Quantitative Indices of Toxicity 38
6.1.5.2 Combining Radionuclide and Chemical Cancer Risks 40
6.1.6 Exposure Assessment 40
6.1.6.1 Alternate Future Uses of the FMC and Simplot Plants 41
6.1.7 Risk Characterization 41
6.1.7.1 Residential Areas 42
6.1.7.1.1 Near Plant Areas 42
6.1.7.1.2 Existing Residential Areas 42
6.1.7.2 Plant Workers 43
6.1.7.2.1 Noncarcinogenic Risks 44
6.1.7.3 Assessment of Potential Health Effects from Inhalation of Airborne
Paniculate Matter (PM10) 44
6.2 Ecological Risk Assessment ; 45
6.3 Uncertainty 47
6.3.1 Uncertainty in the Human Health Risk Assessment 48
6.3.1.1 Air Pathway Uncertainty 48
6.3.1.2 Summary of the Exposure Assessment Uncertainties 49
6.3.1.3 Summary of Toxicity Assessment Uncertainties 50
6.3.2 Ecological Risk Assessment Uncertainties 50
6.4 Need for Action 50
111
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7.0 REMEDIAL ACTION OBJECTIVES .50
7.1 FMC and Simplot Plant 51
7.2 Off-Plant Area 51
8.0 DESCRIPTION OF ALTERNATIVES 53
8.1 Off-Plant area 53
8.1.1 Alternative 01: No Action 53
8.1.2 Alternative 02: Vegetation/Bio Monitoring 53
8.1.3 Alternative 03: Institutional Controls 54
8.1.4 Alternative 04: Removal and Replacement of Soil Cover 54
8.2 FMC Subarea (FMC) 54
8.2.1 Alternative F2: No Further Action 54
8.2.2 Alternative F3: Institutional Controls and Ground water Monitoring .... 55
8.2.3 Alternative F4: Institutional Controls, Surface Controls and Soil Cover, and
Ground water Monitoring 55
8.2.4 Alternative F4A: Institutional Controls, Surface Controls and Capillary Barrier
Cap, and Ground water Monitoring 55
8.2.5 Alternative F5A: Institutional Controls, Source Containment and Native Soil
Cap, and Ground water Monitoring 56
8.2.6 Alternative FSB: Institutional Controls, Source Containment and Asphaltic
Concrete Cap, and Ground water Monitoring 56
8.2.7 Alternative F5C: Institutional Controls, Surface Controls and Multi-Layer Cap,
Source Containment, and Ground water Monitoring '... 56
8.2.8 Alternative F6A- Institutional Controls, Source Containment and Asphaltic
Concrete Cap, Excavation and Disposal, and Ground water Monitoring
56
8.2.9 Alternative F6B: Institutional Controls, Surface Controls and Soil Cover,
Excavation and Stabilization, and Ground water Monitoring 57
8.2.10 Alternative F7-lnstitutional Controls, Surface Controls and Multi-Layer Cap,
and Ground water Monitoring, Extraction and Recycling: 57
8.2.11 Alternative F8B- Institutional Controls, Surface Controls and Asphaltic
Concrete Cap, Excavation and Stabilization, and Ground water Monitoring,
Extraction, Treatment and Recycling 57
8.3 Simplot Plant 58
8.3.1 Alternative S2: No Further Action 58
8.3.2 Alternative S3: Institutional Controls & Ground water Monitoring 58
8.3.3 Alternative S4A: Institutional Controls, Removal/Disposal, Source
Control #1 58
8.3.4 Alternative S4B: Institutional Controls, Removal/Disposal, Ground water
Containment, Source Control #1 59
8.3.5 Alternative S5: Institutional Controls, Removal/Disposal, Source
Control #2 59
9.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 59
9.1 Threshold Criteria .: 59
iv
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9.1.1 Overall protection of human health and the environment 59
9.1.2. Compliance with Applicable or Relevant and Appropriate Requirements
(ARARs) 60
9.2 Primary Balancing Criteria 61
9.2.1. Long-term effectiveness and permanence 61
9.2.2. Reduction of toxicity, mobility, or volume through treatment or recycling
: 61
9.2.3 Short-term effectiveness 62
9.2.4 Implementability 62
9.2.5 Estimated Cost 63
9.3 Modifying Criteria 63
9.3.1 State acceptance 63
9.3.2. Community acceptance 63
10.0 THE SELECTED REMEDY 63
10.1 Simplot Operable Unit (OU) 64
10.1.1 Ground water 64
10.1.1.1 Ground water Extraction (Alternative S4B) 64
10.1.1.1.2 Ground water Extraction System Evaluation 64
10.1.1.2 Improvement to Gypsum Decant System (Alternative S4B).. 65
10.1.1.3 Ground water Monitoring and Evaluations (Alternative SAB) . 65
10.1.2 Air (Alternative S4B) 65
10.1.3 Soils and Solids (Alternative S4B) 66
10.1.3.1 Worker Safety Programs (Alternative S4B) 66
10.1.3.2 Personnel Monitoring (Alternative S4B) 66
10.1.4 Land Use Controls (Alternative S4B) 66
10.1.4.1 Construction of Radon-Resistant Buildings (Alternative S4B)
66
10.1.5 Off-Plant Area 66
10.1.5.1 Fluoride Monitoring (Alternative O3) 67
10.1.5.2 Soils (Alternative O3) 67
10.1.5.3 Ground water Monitoring 68
10.1.6 Estimated costs for the Simplot OU 68
10.2 FMC Operable Unit 68
10.2.1 Contaminated Ground water (Alternative F4/F4A) 68
10.2.1.1 Ground water Monitoring and Evaluation 68
10.2.1.2 Contingent Ground water remedy (Alternative FSB) 69
10.2.1.2.1 Ground water Extraction System Monitoring 70
10.2.1.3 Point of Compliance for Ground water 70
10.2.2 Soils and Solids 70
10.2.2.1 Capping Ponds and Calciner Solids Area (Alternative F4/F4A)
70
10.2.2.2 Railroad Swale (Alternative F4/F4A) 71
10.2.3 Land Use Restrictions 71
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10.2.3.1 Construction of Radon Resistant Buildings (Alternative F4/F4A)
71
10.2.4 Off-Plant Area 71
10.2.4.1 Fluoride Monitoring (Alternative O3) 71
10.2.4.2 Soils (Alternative O3) 72
10.2.4.3 Ground water Monitoring 73
10.2.5 Estimated Cost for FMC Operable Unit 73
10.3 Five Year Review Requirements 73
11.0 STATUTORY DETERMINATIONS 74
11.1 Protection of Human Health and the Environment 74
11.2 Applicable or Relevant and Appropriate Requirements 75
11.3 Cost Effectiveness 76
11.4 Utilization of Permanent Solutions and Alternative Treatment Technologies to the
Maximum Extent Practicable 76
11.5 Preference for Treatment as a Principal Element 76
12.0 Documentation of Significant Differences 77
12.1 FMC Operable Unit Extraction and Treatment 77
APPENDIX A
ADDITIONAL FIGURES AND TABLES A-1
APPENDIX B
RESPONSIVENESS SUMMARY B-1
APPENDIX C
STATE OF IDAHO CONCURRENCE WITH REMEDY C-1
APPENDIX D
METHOD USED TO ESTIMATE CONCENTRATIONS OF RADON
IN INDOOR AIR D-1
APPENDIX E
ADMINISTRATIVE RECORD INDEX E-1
VI
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LIST OF FIGURES
FIGURE TITLE PAGE
1 Regional Setting 6
2 Land Ownership 7
3 Zoning in Vicinity of the Site A-2
4 Schematic Block Diagram at EMF facilities 9
5 Location of Hydrogeologic cross sections A-3
6 A-A' Cross Section (1 of 2) A-4
7 A-A'Cross Section (2 of 2) A-5
8 Contours of Shallow Ground water Elevations A-6
9 Contours of Deeper Ground water Elevations A-7
10 Effects of Plant Productions Wells on Deep Ground water Flowpaths A-8
11 Major Surface Water Features in the Region A-9
12 Prevailing Wind Direction A-10
13 Habitat and Vegetation Cover Types in the Vicinity of the Site 11
14 Major Features of FMC Plant 13
15 Simplot Plant Area 14
16 Surface Soil Sampling Locations A-l 1
17 Cadmium Concentrations in Surface Soils A-12
18 Fluoride Concentrations in Surface Soils A-l3
19 Well Location Map A-14
20 Arsenic Concentration in Shallow Aquifer 32
21 Ground water Flow in the Southwestern Area of the FMC Facility A-15
22 EMF Air Monitoring Sites . A-16
23 Conceptual Site Model A-17
24 Existing Residential Areas 37
25 OffPlant Areas Where Radionuclide Activities Exceed the 10-6 Incremental Risks ... A-l 8
26 OffPlant Areas Where Radionuclide Activities Exceed the 10-5 Incremental Risks ... A-19
27 OffPlant Areas Where Radionuclide Activities Exceed the 10-4 Incremental risks ... A-20
28 OffPlant Areas Where Cadmium Concentrations Exceed a HQ of 1 A-21
29 OffPlant Areas Subject to Residential Use Monitoring A-22
VII
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LIST OF TABLES
TABLE TITLE PAGE
] FMC Facility - Unlined Former Ponds Historical Summary A-23
2 Ratio of Concentrations of Substances Relative to Local Background Soils A-27
3 Summary of On-Site (Plant Area) Surface Soil Analytical Results A-29
3 A Summary of Off-Site (Off-Plant Area) Surface Soil Analytical Results A-30
4 Gross Alpha Activities in Soil at Simplot A-32
5 Summary of Ground water Analytical Results A-33
6 Summary of Air Analytical Results A-37
7 Portneuf River Delta Sediment Comparison to Background A-39
8 Terrestrial Ecologic Investigations Summary for Soil A-40
9 Terrestrial Ecologic Investigations Summary for Vegetation A-41
10 Terrestrial Ecoiogic Investigations Summary for Deer Mice A-44
11 EMF Soil Screening Criteria A-45
12 EMF Ground water Screening Criteria A-47
13 EMF Air Screening Criteria A-49
14 List of COPCs for Site 39
15 Toxicity Values for Carcinogenic Effects A-50
16 Toxicity Values for Noncarcinogenic Effects A-51
17 Toxicity Values for Radionuclides A-56
18 Radionuclides Cancer Risks Current Exposure in Existing Residential Areas A-S7
19 Summary of Radiological Carcinogenic Risks to Residents from Soil and Vegetation A-58
20 Chemical Cancer Risks Current Exposure in Existing Residential Areas A-59
21 Summary of Noncarcinogenic Risks (HQs) to Residents from Soil and Vegetation A-60
22 Hazard Quotients for Cadmium Exposure From Homegrown Produce A-68
23 Summary of Chemical Risks to Residents from Inhalation A-69
24 Summary of Radiological Carcinogenic Risks to Residents from Inhalation A-70
25 Summary of Potential Chemical Cancer Risks for Workers at FMC A-71
26 Summary of Chemical Risks for Workers at Simplot A-73
27 Summary of Potential Radiological Risks for Workers at FMC A-74
28 Summary of Radiological Risks for Workers at Simplot A-76
29 Summary of Noncarcinogenic Risks for Workers at FMC A-77
30 Summary of Noncarcinogenic Risks for Workers at Simplot A-78
31 Maximum and Average PM,0 and TSP Values at Air Monitoring Sites A-79
32 Summary of Ecological COPCs by Media 46
33 HQ for Plants A-80
34 HQ for Mammals A-82
35 HO for Birds A-84
36 Risk Based and Maximum Concentration of COCs in Ground water 52
37 Risk Based and Maximum Concentration of COCs in Surface Water A-86
Vlll
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LIST OF ACRONYMS USED IN THIS DOCUMENT
AFLB American Falls Lake Bed
AOC Administrative Order on Consent
ARAR Applicable or Relevant and Appropriate Requirements
ATSDR Agency for Toxic Substances Disease Registry
BAPCO Bannock Paving Company
BLM Bureau of Land Management
CAA Clean Air Act
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CFR Code of Federal Regulations
COCs Contaminants of Concern -
COPCs Contaminants of Potential Concern
CRP Community Relations Plan
CT Central Tendency
E&E Ecology & Environment
ECAO Environmental Criteria Assessment Office
EMF Eastern Michaud Flats Site
EPA U.S. Environmental Protection Agency
FIP Federal Implementation Plan
FMC FMC Corporation
FS Feasibility Study
HEAST Health Effects Assessment Summary Tables
HI Hazard Index
HQ Hazard Quotient
1CR Incremental Carcinogenic Risk
IDEQ Idaho Division of Environmental Quality
IRIS Integrated Risk Information System
IWW Industrial Wastewater
MCL Maximum Contaminant Level
Mg/Kg Milligrams/Kilograms (parts per million)
NAAQS National Ambient Air Quality Standards
NCP National Contingency Plan
NPDES National Pollutant Discharge Elimination System
NPL National Priority List
NWI National Wetland Inventory
O&M Operation & Maintenance
OSHA Occupational Safety and Health Administration
OU Operable Unit
PM,0 Paniculate Matter less than 10 microns
PRP Potentially Responsible Party
RCRA Resource Conservation Recovery Act
RfD Reference Dose
Rl/FS Remedial Investigation/Feasibility Study
ix
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LIST OF ACRONYMS USED (CONTINUED)
RI Remedial Investigation
RME Reasonable Maximum Exposure
ROD Record of Decision
SF Slope Factor
SIMPLOT J.R. Simplot Company Don Plant
SIP State Implementation Plan
TIP Tribal Implementation Plan
UCL Upper Confidence Limit
USFWS U.S. Fish and Wildlife Service
USGS U.S. Geological Survey
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RECORD OF DECISION
EASTERN MICHAUD FLATS SUPERFUND
SITE
Declaration for the Record of Decision
Site Name and Location
Eastern Michaud Flats
FMC and Simplot Operable Units
Pocatello, Idaho
Statement of Basis and Purpose
This decision document presents the selected remedial actions for the Eastern Michaud Flats Site located
near the city of Pocatello, Idaho. The remedy was developed in accordance with the requirements of the
Comprehensive Environmental Response, Compensation, and Liability Act of 1980,42 U.S.C. §9601 et.
seq. (CERCLA) as amended, and to the extent practicable, the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP), 40 C.F.R. Part 300. This decision is based on the administrative
record for this site.
A letter indicating the State of Idaho concurs with the selected remedy is in Appendix C of this ROD.
The Shoshone Bannock Tribes have substantially participated in the RI/FS and provided comments on
the proposed plan and draft ROD in September 1997. In those comments, which are attached to the
responsiveness summary in Appendix B, the Tribes indicated that they would not concur with the ROD
as drafted. In the subsequent eight months EPA has worked to understand and address the concerns
of the Tribes. This ROD and responsiveness summary has been changed as a result. However, on
some critical issues, EPA could not agree to the changes requested by the Tribes, for reasons explained
in the responsiveness summary. On June 4,1998 EPA received a letter from the Tribes identifying which
actions in the ROD they support and the reasons for non-concurrence on the ROD. This letter is included
in Appendix C of this ROD.
Assessment of the Site
Actual or threatened releases of hazardous substances from this site, if not addressed by implementing
the response actions selected in this Record of Decision (ROD), may present an imminent and
substantial endangerment to public health, welfare, or the environment.
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Description of the Selected Remedy
The EPA has divided the site into two operable units (OUs) in order to facilitate a cleanup of this large
site. Following an agreement with PMC Corporation and J.R. Simplot Company, the owner and operators
of the two industrial plants, respectively, at the site, these operable units each incorporate action for the
Off-Plant areas identified in the Proposed Plan. The operable units are:
FMC operable unit (includes all of the Off-Plant Area)
Simplot operable unit (includes all of the Off-Plant Area)
The remedy described in this ROD addresses both OUs and involves capping contaminated soils,
extraction of contaminated ground water, and monitoring and institutional controls. The major
components of the selected remedy are highlighted below.
FMC Operable Unit
• Cap Old Phossy Waste Ponds and Calciner Solids Storage area and line Railroad Swale
to reduce or eliminate infiltration of rainwater and prevent incidental exposure to
contaminants.
• Monitor Ground water and implement legally enforceable controls that will run with the
land to prevent use of contaminated ground water for drinking purposes under current and
future ownership. Ground water monitoring and enforceable controls will continue until
site contaminants of concern (COCs) in ground water decline to below the Maximum
Contaminant Levels (MCLs) or risk-based concentrations (RBCs) for those substances.
• Implement legally binding land use controls that will run with the land to prevent potential
future residential use and control potential worker exposures under future ownership.
• Implement contingent ground water extraction/treatment system if contaminated ground
water migrates beyond Company owned property and into adjoining springs or the
Portneuf River. Containment of contamination shall be achieved via hydrodynamic
controls such as long-term ground water gradient control provided by low level pumping.
Extracted ground water will be treated and recycled within the plant to replace
unaffected ground water that would have been extracted and used in plant operations.
• Conduct operation and maintenance on capped areas and ground water extraction
system, if implemented.
Simplot Operable Unit
• Implement a ground water extraction system to contain contaminants associated with the
phosphogypsum stack.
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Implement legally enforceable land use controls to prevent potential future residential use
of the Simplot property and control potential worker exposures under current and future
ownership.
Excavate contaminated soils from the dewatering pit and east overflow pond.
Monitor ground water and implement legally enforceable controls that will run with the land
to prevent use of contaminated ground water for drinking purposes under current and
future ownership. Ground water monitoring and enforceable controls will continue until
site contaminants of concern in ground water decline to below MCLs or RBCs for those
substances.
Implement operation and maintenance on the ground water extraction system
Off-Plant Area - Actions Common to Both Simplot and FMC Operable Units
• Implement legally enforceable land use controls and monitoring in the Off-Plant area to
restrict property use due to potential exposure to radionuclides in soils and inform future
property ownerc of the potential human health risks associated with consumption of
homegrown fruits and vegetables
• Monitor fluoride levels around the site in order to determine the levels of fluoride present
and to evaluate the potential risk to ecological receptors. If levels which are measured
indicate a risk may exist, further evaluation would occur followed by source control or
other action, if necessary.
• Conduct ground water monitoring in the off-plant area to: 1) determine the effectiveness
of the Plants' source control measures; 2) insure contaminants are not migrating into the
off-plant area; and, 3) insure that the remedy remains protective of human health and the
environment.
Except as expressly stated in CERCLA, the NCP, or this ROD, the ROD is not designed to address
FMC's cr Simplot's ongoing operations, or to preclude, or in any way affect, the need for the Plants'
ongoing operations to comply with other environmental laws or regulations.
While not part of the selected remedy, the remedy assumes continued operation of the Plants by FMC
and Simplot in compliance with all Federal and State environmental requirements as well as the
applicable closure requirements in the event that either Plant ceases operation. If new information
becomes available that indicates that the remedy is not protective of human health or the environment,
additional CERCLA action may be required.
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Declaration of Statutory Determinations
The selected remedy is protective of human health and the environment, complies with Federal and State
requirements that are legally applicable or relevant and appropriate to the remedial action, and is cost-
effective. This remedy utilizes permanent solutions and alternative treatment (or resource recovery)
technologies, to the maximum extent practicable for this site. However, because treatment of the
principal threats of the site was not found to be practicable, this remedy does not utilize the statutory
preference for treatment.
Because this remedy will result in hazardous substances remaining on-site above health-based levels,
a review will be conducted within five years after commencement of remedial actions to ensure that the
remedy continues to provide adequate protection of human health and the environment.
Chanes C. Clarke / Date
/^Regional Administrator '
ITS. Environmental Protection Agency
Region 10
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RECORD OF DECISION
EASTERN MICHAUD FLATS Superfund SITE
DECISION SUMMARY
1.0 SITE NAME, LOCATION, AND DESCRIPTION
1.1 Site Name and Location
The Eastern Michaud Flats Superfund (EMF) site is located in Southeastern Idaho, approximately 2.5
miles northwest of Pocatello, Idaho (See Figure 1 - Regional Setting). The EMF site includes two
adjacent phosphate ore processing plants- the FMC Corporation Elemental Phosphorus Plant (FMC) and
the J.R. Simplot Company Don Plant (Simplot)- both of which are active facilities that have been
operating since the 1940s. These plants occupy 2,475 acres of the site with approximately 1,450 acres
associated with FMC operations and approximately 1,025 associated with the Simplot Don Plant. Figure
2 shows land ownership around the FMC and Simplot Plants. The entire site encompasses the areal
extent of contamination deemed necessary by EPA for implementation of any response action and
includes both the Company Plant areas and surrounding Off-Plant areas.
1.2 General Site Description
The EMF Site is located at the base of the northern slope of the Bannock Range, where it merges with
the Snake River Plain. The southern part of the site extends into the foothills of the Bannock Range.
The northern part of the site is located at the southeastern edge of the Michaud Flats. The eastern edge
of the site is approximately 2.5 miles northwest of Pocatello, Idaho. The nearest residence is within Vfc
mile north of the Simplot plant and FMC property.
The following is a brief overview of the major features of the site.
1.2.1 Land Use
The EMF site includes land on the Fort Hall Indian Reservation, Bannock and Power Counties, and
portions of the cities of Pocatello and Chubbuck. Fort Hall Indian Reservation land in the vicinity of the
site is mainly agricultural. The Bureau of Land Management (BLM) lands in the vicinity of the site are
designated as multiple use. Unincorporated land in Bannock and Power Counties is mostly agricultural
with scattered residences. Pocatello and Chubbuck land in the vicinity of the site is primarily zoned for
residential use. Figure 3 shows the zoning in the vicinity of the site.
Approximately 40% of the land in the vicinity of the site is used for agricultural purposes (50% to 60% is
actively used; the rest is fallow); approximately 10% of the land is residential; 15% to 20% is industrial;
10% is occupied by the Pocatello Municipal Airport; less than 5% is commercial; and
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FORT HAUL
aonous
RIVER
_ INTERMTTTENT STREAM
SPRING
TOPOGRAPHIC CONTOUR
UNION PACIFIC RAILROAD
CANAL
EMF PROPERTY LINES
MPOOSESfWNCS
RSHFVU1
UICHAUD
FLATS
MCATEU.OSEWAGE
THEATUEKT PLANT
Contour Intervals
Above 4500 ft elevation: 250ft
Below 4500 n elevation: SO ft.
IPOCATEUO
MUNICIPAL
AWOHT
Note:
Base map adapted from Trimble. 1976
andlrom USGS Michaud (1971) and
Pocatello North (1971) 7.5 minute
topographic quadrangles.
\
UNION PACF1CIW
SLUDGE WT
\
McCAflTY-S/PACtnC
MBC AND FUR SITE
SIMPLOT
SUBAREAX
EASTERN MICHAUD FLATS
POCATELLO, IDAHO
f EASIBlrTY STUDY
REGIONAL SETTING
c,
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CfTY OF POCATELLO
COUNTY 'fr:
\STATE | uS?«
fo\ TN^ BANNOCK
JvR. SlMPtQTCOMPANY -iv.'/
\ i I i c"
'
•:|- FMC .-L,.fl
IDAHO POWER COMPANY
EASTERN MCHAUO FLATS
POCATEUO. IOAIKD
\ Rl^ERl^iON | ^ATBLM LANDS
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the remainder is undeveloped sagebrush steppe, mainly in the hills south of the site, or riparian wetland
bordering the Portneuf River in the Fort Hall bottoms area north of the site.
Four schools are located within the EMF study area: Wilcox Elementary School and Hawthorne Junior
High School in the City of Pocatello; Chubbuck Elementary School in Chubbuck; and, the Idaho State
Aircraft Mechanics School at the Pocatello Airport. In addition, six licensed day-care centers and one
retirement home, the Cottonwood Cove Retirement Community, are located in the study area. There
are no hospitals or nursing homes within the study area.
1.2.2 Geology and Hydrogeology
Volcanic bedrock and coarse gravel underlay the site. The general stratigraphy in the study area includes
(from the bottom) volcanic bedrock units, coarse volcanic and quartzitic gravel, fine-grained sediments
of the American Falls Lake Bed, the Michaud gravels, and calcareous silts and clays (Figure 4 shows a
schematic block diagram at the site). The latter surface soils range in thickness from 10 to 40 feet and
have an alkaline pH that neutralizes acidic solutions and precipitates metals. (Figure 5 shows the
location of hydrogeologic cross sections and Figures 6 and 7 show the east - west cross section across
the FMC and Simplot Plants).
Ground water at the site flows from the Bannock Range foothills toward the north/northeast through
unconsolidated sediment overlying the volcanic bedrock. Figures 8 and 9 depict the ground water flow
patterns at the FMC and Simplot Plants. Shallow and deep aquifer zones, separated by confining strata,
are present in the Plant areas and to the north. Depths to water in the shallow aquifer range from 170
feet below ground surface in the Bannock Range area to 55 feet below ground surface in the Michaud
Flats area. Shallow ground water flows into the valley where it mixes with the more prolific Michaud Flats
and Portneuf River ground water systems. Ground water within the deeper aquifer is either captured by
production wells at the Plants or continues northward where it flows upward to the shallow aquifer (Figure
10 depicts the effects of plant production wells on deep ground water flowpaths). The shallow ground
water and a significant portion of the deeper ground water flowing under the Plants discharges to the
Portneuf River through Batiste Springs, Swanson Road Springs, and as baseflow to the River in the reach
between these springs.
1.2.3 Hydrology (Surface Water)
t
The Portnuef River, which lies to the east and north of the Plants, is the major surface water at the site.
To the south of Interstate 86, it is a losing stream. To the north of Interstate 86, it is a gaining stream fed
by ground water base flow and a series of springs. The Portneuf River flows into .the American Falls
Reservoir. Figure 11 shows the major surface water features in the region.
Rainwater which falls or flows onto the FMC and Simplot Plants is captured and controlled on-site such
that there is no stormwater runoff from the facilities. The only surface water flowing from the EMF
facilities is the permitted discharge of non-contact cooling water through the IWW ditch to the Portneuf
River.
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EXPLANATION
FACILITY BUILDINGS
^ FACILITY PROPERTY BOUNDARIES
PORTNEUF RIVER
NOT TO SCALE .
SIDES OF BLOCK REPRESENT
APPROXIMATELY 8000 FEET
HEIGHT OF BLOCK REPRESENTS
APPROXIMATELY 400 FEET
BECHTEL ENVIRONMENTAL, INC.
3AM FRAMCISCO
EASTERN MICHAUD FLATS
POCATELLO. IDAHO
Schematic Block Diagram Showing
Stratigraphic Setting at EMF Facilities
21372
FIGURE 4-
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1.2.4 Climate
The EMF site is located in a semi-arid region, with approximately 11 inches of total precipitation during
a year. Net annual potential evapotranspiration rates1 in the area exceed annual precipitation. Prevailing
winds are from the southwest as shown in Figure 12. However, there is also a secondary wind
component out of the southeast which appears to be a drainage wind that flows out of the Portneuf River
valley, primarily at night.
1.2.5 Ecology
The FMC and Simplot plants are industrial facilities and much of the land surface has been disturbed
resulting in limited areas with vegetation. Major terrestrial vegetation cover types and wildlife habitats
around the Plants include agricultural, sagebrush steppe and wetland/riparian. Figure 13 shows the
habitat and vegetation cover types in the vicinity of the site. Wildlife habitats in the vicinity of the EMF
site include: sagebrush steppe, grassland riparian, cliff and juniper. Listed species which occur within
the vicinity of the Site include the bald eagle, the peregrine falcon and possibly the orchid Ute Ladies'-
tresses. The bald eagle and the orchid Ute Ladies'-tresses are listed as threatened, and the peregrine
falcon is listed as endangered under the Endangered Species Act.
The most significant aquatic habitats in the vicinity of the site are the Portnuef River and associated
springs and riparian corridor and the Fort Hall Bottoms (a sacred site to the Shoshone-Bannock Tribes).
These areas are designated wetlands under the National Wetland Inventory of the United States Fish and
Wildlife Service. The Portneuf River supports an extensive riparian community, which is an important
source of food, cover, and nesting sites for many wildlife species. Thousands of individuals of numerous
migratory bird species use areas in and near the site, particularly the Fort Hall Bottoms.
1.3 SiteSubareas
During the course of the Rl, all property outside of the FMC and Simplot operational areas (beyond their
fence line) was described as "off-site." Although the term "site* or "on-site" is defined in EPA regulations
as, "the area! extent of contamination and all suitable areas in very close proximity to the contamination
necessary for implementation of the response action," generally, site boundaries are not fixed until the
Rl is completed and the "areal extent of contamination" has been ascertained. In the risk assessment
and FS, adjacent company owned properties, some of which were acquired during the Rl, are considered
to be part of the plant and were not evaluated for either current or future residential use. The FS and risk
assessment refer to these areas as the FMC Subarea, Simplot Subarea, and Off-site Subarea based on
ownership in order to facilitate the RI/FS process prior to precise fixing of site extent or boundary.
1 Evapotranspiration is highly variable from point to point and is highly dependent on the presence of
vegetation.
10
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HABITAT AND VEGETATION
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Figure 13
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For clarity, the proposed plan and this ROD refer to these areas as the FMC Plant, Simplot Plant, and
Off-Plant areas based on ownership and on the RI/FS documents. "Off-site" would be inaccurate
because the Off-Plant is officially within the site. The three areas of the site are discussed separately
below:
1.3.1 FMC Plant Area
The FMC Plant Area is defined as all properties owned by FMC Corporation and is shown in Figure 14.
These properties were owned by FMC at the beginning of the remedial investigation in 1992, with the
exception of the Batiste Property. This 23-acre parcel was purchased from the Union Pacific Railroad
by FMC in August 1995 and is shown as Batiste Springs on Figure 2. The FMC Plant operations areas
are primarily those portions of the FMC Plant Area located south of Highway 30. This area includes all
ore processing, byproduct handling^ and byproduct and waste storage facilities. The northern FMC
properties are defined as all adjacent property owned by FMC which is within the FMC Subarea north
of Highway 30. The majority of the FMC Plant is located within the boundaries of the Fort Hall Indian
Reservation.
The FMC plant manufactures elemental phosphorus. The phosphate rock is crushed, conveyed and
formed into briquettes. The briquettes are heated or "calcined" to remove organic material and water,
and to form heat-hardened nodules for further processing. Calciner emissions go through a series of
primary and secondary wet scrubbers. The nodules are cooled and blended with coke and silica before
being fed to an electric arc furnace. In the furnace high temperatures drive off phosphorus and carbon
monoxide. Furnace off-gases pass through electrostatic precipitators to remove dust before entering
condensers, where phosphorus is condensed into a liquid. The carbon monoxide is used as a primary i
fuel and any excess is flared. Molten residues are periodically withdrawn from the furnace and allowed
to solidify into the by-product slag and co-product ferrophos. The slag, predominantly calcium silicate,
is stockpiled at the facility. Various lined and unlined surface impoundments have been used to manage
process wastewater containing phosphorus. Bannock Paving Company (BAPCO) operated a paving and
aggregate handling facility on land leased from and adjacent to the FMC Plant during the Rl. Activities
periodically conducted at this facility included asphalt batching, coke drying, and slag and ferrophos
crushing. Operations at BAPCO were discontinued on March 12,1995.
1.3.2 Simplot Plant Area
The Simplot Plant area is defined as all those properties and operating facilities owned by the J.R.
Simplot Company and is shown in detail in Figure 15. The Don Plant area is defined as the portion of
the Simplot Subarea located to the south of the Union Pacific Railroad, which runs parallel to Highway
30. The Don Plant area includes all ore processing, byproduct and product handling, and byproduct and
waste storage facilities. The northern Simplot properties are defined as all contiguous property owned
by the J.R. Simplot Company to the north of the Don Plant northern fence line. The northern Simplot
properties include ponds used in the treatment of various non-contact water streams, laboratory wastes
and storm water from the Don Plant. The Portneuf River flows through the northeastern portion of the
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-— FMC Mccarty Un«
FortHaf Man ReMrnfton
Boundvy
Orion PK*C Rairatd
\ „ I Surag»An*>
' ™ I
I' •'>'•! btaOM Simgt Ana
WWTP
EASTERN H1CHAUO FLATS
POCATELLO. B5AHO
FEASIBUJTY STUDY
FUC OKIUTWG r»ctmes
-------
AREA OF
DETAIL .
Si"
LEGEND:
O STORAGE TANK
UNION PACinC RAILROAD
OTHER PWNT STRUCTURE
EASTERN MCHAUD FLATS
POCAmi.0. DAHO
FtASBUTY STUDY
SIWt.OT SUBAREA
srre MAP
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Simplot Subarea, but for the purposes of the FS it was included in the Off-Plant Subarea. The Simplot
Subarea is not located on the Fort Hall Indian Reservation.
The Simplot plant processes phosphate rock into phosphoric acid and other fertilizers. The phosphate
rock is ground and slurried at the mine and transported to the facility by pipeline. There it is reacted with
sulfuric acid to produce phosphoric acid and by-product gypsum (calcium sulfate). The phosphoric acid
is used to make various grades of fertilizer or is concentrated to produce stronger acids which are
feedstocks to subsequent production lines. A system of baghouses and scrubbers are used to control
air emissions. The gypsum is slum'ed with water and transported to an unlined gypsum stack south of
the processing facilities. Other process waters are collected and treated (pH adjustment) in a series of
lined ponds. The treated water is nutrient rich and sold for irrigation/fertilization.
The FMC and Simplot plants are both operating facilities and, together, currently employ approximately
1,000 people.
1.3.3 Off-Plant Area
In the FS, the Off-Plant area is all land surrounding the FMC and Simplot Plants with contamination
originating from the Plants. A general description of land use in the vicinity of the FMC and Simplot
Plants is provided in section 1.2.1.
The area which comprises the Offsite Subarea includes urban commercial and residential areas,
agricultural areas, and areas of rangeland for cattle grazing within the Fort Hall Indian Reservation and
Bureau of Land Management (BLM) lands. Major vegetation cover and wildlife habitat types existing in
the areas include sagebrush steppe, riparian/wetlands, agriculture, and disturbed/urban areas.
For the purpose of implementing this ROD, the off-plant area is divided into the following areas:
Areas Subject to Land Use Controls
These are areas where soil contaminant levels exceed a HQ of 1 for cadmium (RME case) and/or which
pose a 1 in 10,000 excess risk from radium-226 as shown in Figures 27 and 28. These areas include
the Interstate 86 Right-of-Way (51 acres); Chevron Tank Farm (20 acres); City of Pocatello Property (326
acres); a portion of the land owned by private party named R. Rowland, and a portion of BLM lands to
the SW of the FMC facility.
Areas Subject to Fluoride Monitoring
This area generally corresponds to the 3-mile radius of the RI/FS study area. (While the area! extent of
fluoride contamination in the vicinity of the site is not clearly definable, and some contamination may
extend beyond this boundary, it appears that the greatest impacts to the environment would be found
within the 3 - mile radius. However, there may be specific areas outside the three mile radius, which
may contain sensitive species or be of particular ecological or cultural value where sampling should also
occur).
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Areas Subject to Company Monitoring for Residential Development
This area as shown in Figure 29 was not found to exceed the criteria established for the imposition of
Land Use Controls but was either close enough to the threshold of a HQ of 1 for cadmium, or adjacent
to lands that exceeded the threshold, to warrant notification to current and future property owners if
residential use is likely to occur.
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
2.1 Historical Land Use
2.1.1 FMC Plant
FMC has produced elemental phosphorus from phosphate shale since 1949. The FMC plant produces
elemental phosphorus which is sold and used in a variety of products from cleaning compounds to foods.
The raw materials for the process are phosphate ore, coke, and silica. Ore is shipped to the plant in rail
cars and stockpiled at the plant. The primary by-products from the production process are slag,
ferrophos, carbon monoxide and several aqueous streams (phossy water/solids, precipitator slurry,
calciner water/solids, and industrial wastewater). In the past many of the aqueous streams were
managed in unlined surface impoundments. Table 1 provides a historical summary of unlined ponds at
FMC.
The FMC facility is located within the original boundaries of the Fort Hall Indian Reservation on land
originally allotted to individual Shoshone-Bannock Tribal Members. Ownership of the land changed when
the Bureau of Indian Affairs issued to those Indian land owners who applied for and were granted
Certificates of Competency on the lands. Ownership of the lands was taken out of trust and fee patents
were issued. The Shoshone-Bannock Tribes, as a sovereign nation, and with the Bureau of Indian Affairs
as trustee, retain full jurisdiction over all lands and resources within the present reservation boundaries.
2.1.2SimplotPlant
The Simplot plant produces 12 principal products including five grades of solid fertilizer and four grades
of liquid fertilizers. The raw materials for their processes are phosphate ore, which is transported to the
plant via a slurry pipeline from the Smoky Canyon mine, sulfur, air, and natural gas. The primary waste
or by-product from the Simplot Plant is phosphogypsum (gypsum) which is transported to large unlined
stacks south of the processing plant. The plant also treats water from the various processes which is
nutrient rich and is sold for irrigation and fertilization.
The Simplot plant has been in operation at this location since 1944. The Simplot plant is not within the
boundaries of the Fort Hall Reservation and therefore is not subject to tribal jurisdiction.
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2.2 Previous Studies
The Eastern Michaud Flats site has been the subject of a number of historical investigations that focused
on various media, including springs, ground water, surface water, river sediments, air quality, and
ecology. Appendix A of the Rl report provides a summary of the previous investigations in the vicinity
of the site. The following are conclusions from a few of the investigations on ground water.
Between 1972 and 1973, the Idaho Department of Health and Welfare conducted a ground water
monitoring study downgradient of the two facilities. Ground water samples analyzed by the State of
Idaho indicated levels of arsenic, lead, and cadmium above the Primary Federal Drinking Water
Standards. A downgradient well at the Pilot House Cafe was condemned in 1976 due to high arsenic
levels.
In 1977, the United States Geologic Survey (USGS) prepared an Environmental Impact Statement to
address the development of phosphate resources in southeast Idaho. In the EIS, relatively high levels
of phosphate (0.35 to 7.5 parts per million) detected in samples from Batiste Spring were attributed to
discharges to the Portneuf River from the FMC and Simplot facilities.
Studies by Perry et al., 1990 and Goldstein, 1981 showed increased sulfate, calcium, and nutrient
concentrations at Batiste Springs relative to the other springs' studies. Water quality of Batiste Spring
was described by Balmer and Noble (Goldstein, 1981) as showing an increase in levels of hardness,
chloride, sulfate, phosphate, nitrate, and ammonia from 1930 through the 1970's. The report also found
fluctuating concentrations of mercury, arsenic, and cadmium in Batiste Spring in the 1970's.
During 1987, Ecology & Environment (E&E) conducted a site inspection for EPA at FMC and Simplot.
A total of 24 wells (six production, 13 monitoring, and five domestic) and one spring was sampled to
assess the extent of possible ground water contamination downgradient of the two facilities. E&E
concluded that water-bearing intervals underlying the facilities contain metals at concentrations exceeding
federal drinking water standards. There also appeared to be a potential plume in the shallow water-
bearing interval northeast of the FMC facility. In pond, waste, and soil samples, E&E found elevated
levels (ten times greater than background levels or three times greater than the respective analytes'
detection limit) of cadmium, chloride, total chromium, copper, fluoride, and selenium.
2.3 Listing on the National Priorities List
The Site was listed on the National Priorities List (NPL) on August 30, 1990 (Federal Register Volume
55, Number 169, 35502). EPA took this action pursuant to its authority under Section 105 of CERCLA.
EPA, FMC, and Simplot negotiated an Administrative Order on Consent (AOC). under which FMC and
Simplot agreed to conduct an RI/FS for the EMF site. The AOC was issued by EPA on May 30, 1991.
2.4 Company Actions to Date
Since 1991, Simplot and FMC have completed a number of actions, which have resulted in significant
environmental improvements. Some of these improvements were made independently by the
Companies, and others were done to comply with state, tribal, and/or federal requirements. These
17
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actions have helped to reduce the extent of the Superfund remedy as compared to what might have
been necessary if the facilties were no longer in operation or abandoned. The following is a summary
of these actions:
2.4.1 Simplot
Two areas within the former unlined ditch which conveyed water to the treatment ponds
were excavated. The removed soil was incorporated into the gypsum stack. The areas
had been identified by Remedial Investigation sampling as containing the highest
concentrations of contaminants within the ditch. A sealed pipe was installed and the ditch
subsequently filled with clean soil. This action has eliminated the potential for worker
exposure to the soils in the ditch through removal and covering and eliminated the
hydraulic head from the conveyed water.
The East Overflow Pond was removed from service and a new single-lined pond was
installed in an adjacent area. Monitoring indicated that discontinuation of use of the East
Overflow Pond and use of a new lined pond has resulted in a significant improvement in
local ground water quality.
A lined holding pond was installed in the irrigation water treatment system, and a new
liner was installed in the existing holding pond. These actions have reduced the potential
for seepage from the holding pond.
The leaking transfer line between the Nitrogen Solutions Plant and the Urea Ammonium
Nitrate (UAN) storage tank was repaired. This action has reduced the input of nitrogen
compounds from this pipe to ground water.
The gypsum thickeners in the phosphoric acid plant were upgraded to reduce the water
content of the slurry sent to the stack. This upgrade has reduced the slurry water content
by approximately 1 to 3 percent. Based on recent operating data, this value corresponds
to a reduction in water sent to the stack of between 25 and 70 gallons per minute. This
is expected to reduce the rate of seepage from the stack to ground water.
Use of chemical flocculants in the gypsum thickeners was initiated to increase the solids
content and improve the settling characteristics of the slurry. Use of these flocculants,
combined with the increased carbon content of the gypsum (due to the discontinuation of
the use of the calciners) has resulted in a reduction of the rate of seepage through the
gypsum stack as evidenced by the increased wetness of the gypsum used for dike
building and increased size of the ponded areas.
A new rim ditching method was initiated on the gypsum stack which allows for a more
rapid construction of a smaller dike and has resulted in the current six weeks slurry
application cycle. This has effectively increased the potential evaporative surface on an
annual basis. It has also reduced the duration of standing water (applied head) over any
one part of the stack, further reducing seepage. Ground water level fluctuations in areas
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close to the stacks have been relatively small as compared to wider fluctuations in the
past. This provides some evidence that seepage has been reduced by these
modifications.
Historical delivery of phosphate ore was by rail car, with the ore being stored onsite in a
pile. In September 1991, delivery by pipeline of an ore slurry was initiated, and all rail car
delivery, dry ore handling and pile storage ceased. This has significantly reduced point
source and fugitive air emissions associated with the former bulk ore handling and storage
procedures.
From 1960 to 1991, calciners were used to reduce the organic content of the phosphate
ore before it was introduced to the phosphoric acid process. The decommissioning of the
calciners has reduced point source emissions to air.
Certain roads within the Don Plant area have been paved. This paving has reduced
fugitive air emissions.
Additional air emission control systems have been installed on certain units within the
plant, including scrubbers on the filters and tank farm in the phosphoric acid plant, a
second absorber in the solutions plant, and a scrubber in the ammonium nitrate facility.
Existing air pollution control systems have been upgraded, including systems in the
Granulation II Plant, the Nitric Acid Plant, and in the central boilers.
Enhanced maintenance has been initiated on the reclaim cooling towers, which has
reduced losses due to drift and therefore total air emissions from the towers.
2.4.2 FMC
The most significant changes which have occurred within the FMC Subarea since the RI/FS AOC was
issued include:
The slag pit sump was dewatered in March 1991.
• The John Zink scrubbers were placed in service in December 1991 with the goal of
reducing radionuclide air emissions.
Pond 8S, a formerly utilized unlined pond, was covered and dewatered in the summer of
1994 as a temporary measure.
The railroad swale, an area which receives stormwater runoff from the operating areas
of the plant, was partially lined in 1994.
New Pond 16S, built to meet RCRA minimum technology requirements (MTRs), was
placed in service in 1993.
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Since August 1993, FMC has paved approximately 5 miles (8 km) of formerly unpaved
roadways. In addition, approximately 200,000 ft2 (18,580 rfi) of formerly unpaved
nonroadway plant areas have been paved.
A new, lined solar drying area for calciner pond solids was constructed and placed into
operation in 1993.
Use of septic systems was eliminated on a plant-wide basts. The entire facility was
connected to the municipal sanitary sewer system during 1995.
A new system for waste management of precipitator slurry has been initiated, using lime
precipitation.
. Coke unloading was enclosed to control fugitive dust. Dust from this operation is collected
and recycled to the process. This modification was placed in service in toay 1995.
In August 1993, ventilation and dust collection for ore screening and crushing was
improved sufficiently so that the requirement that respirators be worn in the area was
eliminated.
Furnace tap hoods were modified for chill pits areas to improve collection of emissions
from slag and ferrophos tapping. These modifications were completed in phases from
1992 to 1995.
• The furnace, proportioning, briquetting and shale buildings were tightened in 1994 to
reduce fugitive emissions.
In 1996, the recycling hopper at the ore crusher was improved, and a windscreen was
installed to reduce fugitive emissions.
The Bannock Paving Co. is in the process of removing stockpiles of materials and ceasing
. all operations within the FMC? Plant.
2.5 History of EPA Enforcement Activity -
On May 30, 1991, FMC and Simplot were issued an AOC by EPA to conduct the RI/FS pursuant to
Section 106 of CERCLA 42 U.S.C.§9606.
2.5.1 FMC Plant
FMC submitted a RCRA Part A permit application on November 19, 1980, and subsequently withdrew
the application on February 18, 1981. The withdrawal of the Part A permit application was due to a
federal law. known as the Bevill Amendment which exempted waste generated from mineral and ore
industry production. A portion of the exemption was lifted on March 1, 1990. which made mineral
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processing wastes, previously exempt, subject to RCRA. FMC resubrnitted the Part A application on
February 27, 1990. A Part B permit application was submitted in 1991.
FMCs National Pollutant Discharge Elimination System (NPDES) permit was issued on November 24.
1982, and expired November 23,1987. FMC has applied for renewal of the NPDES permit. The current
permit authorizes the discharge of non-contact cooling water from the industrial wastewater (IWW)
cooling basin to the Portneuf River and regulates thermal loading.
On October 12,1993, EPA signed an Action Memorandum, under the authority of Sections 104 and 122
of CERCLA, authorizing FMC to remove the hydraulic head and begin interim capping of pond 8S which
is a RCRA regulated unit. Action at this unit is discussed in more detail in section 4.2 of this ROD.
In July 1993, EPA's National Enforcement Investigation Center conducted a multimedia compliance
investigation of the FMC facility. Based upon the findings of this investigation. Notices of violation under
RCRA were issued on March 5,1993 and August 3, 1994.
In 1997 a NOV was issued to FMC for violation of reporting requirements under the Emergency Planning
and Community Right-to-KnowAct of 1986. In 1998 a fine of $262,000 was imposed for these violations.
2.5.2 Simplot Plant
The most recent enforcement action at the Simplot plant was a 1994 Notice of Violation issued by the
Idaho Division of Environmental Quality (IDEQ) for alleged hazardous waste generator violations. In April
1995, Simplot agreed to an AOC from IDEQ to resolve the alleged violations. All terms of this AOC were
met by May 29.1996. There have been no documented violations of the State of Idaho air requirements
during the course of the Rl from 1991 to the present.
2.5.3 Off-Plant Area
There have not been any enforcement actions relating to the Off-Plant area
FMC and Simolot have complied with the requirements of the AOC for the RI/FS.
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
EPA developed a Community Relations Plan (CRP) for the Eastern Michaud Flats site. The CRP was
designed to promote public awareness of EPA' activities and the investigations and to promote public
involvement in the decision-making process. The CRP summarizes the concerns of local citizens,
interest groups, industries, and local government representatives.
There have been a number of activities during the course of the RI/FS in an effort to keep the public
informed about the progress and the results of the work at the site. The following is a summary of these
activities:
June 6, 1997 Fact sheet: Public Comment Period Extension
May 13 & 14, 1997 Public Hearings conducted in Pocatello and Fort Hall. Idaho
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April 21, 1997 FS Proposed Plan Fact Sheet
March 5. 1997 Idaho State Journal Article on Proposed Plan
Sept 10, 1995 Idaho State Journal Article on Risk Assessment Findings
August 16, 1995 Idaho State Journal Article on Air Monitoring Findings
October 28, 1993 Fact Sheet on Pond Closure at FMC
September 29,1993 Fact Sheet on first round of sampling results
March 9, 1993 Remedial Investigation Update
April 15, 1992 Remedial Investigation Update/Ground Water Monitoring Program
December 23,1991 Current Site Activities/Description of Community Concerns
December 20,1991 Community Relations Plan
September 1991 Introduction to Superfund Process Fact Sheet
January 23,1991 Congressional Update: Special Notice Letters Sent to Potentially
Responsible Parties
The RI/FS was released to the public with the proposed plan in April 1997. The Proposed Plan, which
identified EPA's preferred alternative, was mailed to individuals on the EMF mail list. All of the
documents mentioned above, as well as previous reports from earlier investigations, were made available
to the public in the Administrative Record located at the places listed below:
Idaho State University Library
Government Documents Department
9th and Terry
Pocatello, Idaho 83209
U.S. Environmental Protection Agency
Region 10
Park Place Building
1200 Sixth Avenue, 7th Floor Records Center
Seattle, Washington 98101
EPA published a notice of the availability of these documents in the Idaho State Journal and Shoshone
Bannock News on April 21, 1997. EPA met with the Shoshone Bannock Tribes Business Council on
January 14, 1997, and IDEQ on January 13, 1997, to discuss EPA's Proposed Plan for cleanup and to
answer any questions. The public comment period on the Proposed Plan was held from April 21, 1997
to July 10, 1997. EPA held public meetings May 13-14, 1997, in Pocatello and on the Fort Hall
Reservation. At these meetings, representatives of EPA. FMC, and Simplot gave presentations on the
findings of the Rl and risk assessment and proposed plan, and then answered questions about the
proposed cleanup and remedial alternatives under consideration. The Responsiveness Summary, which
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is Appendix B of this ROD, contains EPA's responses to the written and oral comments that were
received during the comment period. This decision is based on the Administrative Record for this site.
EPA has kept local, state, tribal, and federal officials who could be affected by activities at the site
informed through frequent updates and briefings.
EPA will continue to keep all interested parties informed about each significant step of the Superfund
process through the final decision and clean up of the Eastern Michaud Flats site.
4.0 SCOPE AND ROLE OF RESPONSE ACTION
The FMC and Simplot Plants are operating facilities. Except as stated expressly in CERCLA, in the NCP,
or in this ROD, this ROD is not designed to either address the Plants' ongoing operations or preclude or
in any way affect the need for FMC's and Simplot's ongoing operations to comply with other
environmental laws or regulations. The selected remedy assumes continued operation of the plants in
compliance with all Federal and State environmental requirements as well as any applicable closure
requirements in the event either plant ceases operation.
The remedy selected by EPA and documented in this ROD includes the remedial actions deemed
necessary for the site to protect human health and the environment. The risk assessment determined
that exposures to contaminated soils and ground water pose the greatest risks to human health and the
environment. The control of these risks is a principal part of the remedial actions described in the
selected remedy. Risks from inhalation of airborne contaminants are lower than from soil and ground
water but are still great enough to be of potential concern, particularly for plant workers. Implementation
of control requirements under the Clean Air Act will reduce plant emissions and reduce potential risks
from airborne contaminants.
All of the remedial actions are included in this decision, and no additional Operational Units or projects
are proposed. Therefore, this ROD can be identified as the "Final" ROD since no other protective
actions, except those otherwise referenced by applicable regulation (i.e., RCRA closures) or actions
being conducted by other regulatory programs, are necessary at this time. In addition to this ROD, the
EPA Air and RCRA programs are actively involved in resolving a number of regulatory issues at the FMC
facility which have some bearing on the CERCLA work. These program activities are discussed briefly
below:
4.1 Air
EPA has promulgated National Ambient Air Quality Standards (NAAQS) as authorized under Section 109
of the Clean Air Act (CAA). These standards are based on the latest scientific health information and are
designed to protect public health with an ample margin of safety. Areas violating any NAAQS are
required to develop a State Implementation Plan (SIP), which must include enforceable emission
limitations on sources of air pollution, to bring the area back into attainment. Portions of Power and
Bannock Counties in Idaho, including certain portions within the Fort Hall Indian Reservation, violate the
NAAQS for paniculate matter exceeding regulatory criteria (PM,0) (particulate matter of 10 microns or
23
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less). EPA is responsible for developing a Federal Implementation Plan (FIP) for that portion of the PM10
nonattainment area within the Reservation. (Simplot is subject to regulation under the Clean Air Act and
State Air permits under a State Implementation Plan (SIP) to Construct and Operate pursuant to IOAPA
16.01.1012 (Rules and Regulations for the Control of Air Pollution in IdaholV
EPA's Air Program anticipates publishing a notice of proposed rulemaking during 1998. Public meetings
and workshops will be scheduled to discuss the contents of the FIP control strategy. At the time of
proposal, the public will be provided a 60-day review and comment period. Promulgation of rules for the
FIP will occur after EPA has responded to the public comments. EPA fully anticipates that control
requirements for FMC in the FIP will help the area to attain the NAAQS. Full implementation of all control
technologies at the FMC Plant may take up to four years after final rules are set, however, EPA expects
to see emission reductions and improvements in air quality within six months of finalizing the rule.
In addition to controls for PM-10 and Section 107 criteria air pollutants, FMC has been identified as a
source of certain hazardous air pollutants (HAPs) listed in section 112 of the Clean Air Act and will be
subject to Maximum Achievable Control Technology (MACT) by November 15,2000. Unlike Section 107
air pollutants like PM-10, Section 112 HAPs are effective immediately upon the promulgation of an EPA
rule which links specific HAPs to specific types of facilities. These rules are therefore not subject to
implementation plans by a state, tribe or the federal government. A specific rulemaking linking type of
facility with specific HAPs is required because Congress listed 188 different HAPs in Section 112, and
a blanket requirement that every facility test to be certain they are meeting every one of them, would be
excessively expensive, time consuming and burdensome to administer. Section 112 requires rules to
examine industrial processes and requires compliance with those HAPs the facility actually generates
based on its function. A Section 112 like regulatory process for PM-10 would have obviated the
SIP/TIP/FIP problem at FMC year ago, but EPA is no more able to apply Section 112 to FMC's PM-10
emissions than it is to apply Superfund. Because of the ongoing FIP development efforts, the findings
of the human health risk assessment, and the role of Superfund at operating facilities this ROD does not
include action for ongoing emissions from the plants.
4.2 RCRA
FMC is an operating facility regulated under the Resource Conservation and Recovery Act regulations
(RCRA) for management of hazardous waste. EPA implements these regulations on Tribal land
because even RCRA- authorized states, like Idaho, do not have jurisdiction. Currently, the various waste
ponds at FMC can be divided, for purposes of closure, into three broad categories which are discussed
below:
Current Ponds
The units where the RCRA operational and closure requirements are applicable include Ponds 11-16S,
8S, 8E, and 9E. These ponds either are currently in use, or have been in use since 1980, for
management of hazardous waste. The RCRA regulated units at FMC are subject to specific standards
for closure, characterization of releases, and ground water corrective action. RCRA closure requirements
at 40 CFR §265.111, require closure to: 1)minimize maintenance and 2)control, minimize or eliminate
releases to the extent necessary to protect human health and the environment after closure has been
completed.
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Former Ponds
The specific phossy waste ponds and calciner solids areas, which are the subject of this ROD (1S-7S.
1E-7E, 9S and 10S), received similar wastes as some of the current RCRA units. However, they were
taken out of service and closed long before the RCRA requirements became effective. Closure of these
pond areas was accomplished via a variety of mechanisms including excavation of some material,
oxidation of phosphorus, drying, and/or placement of soil or concrete covers. Table 1 provides a
historical summary of the former unlined ponds. Due to the time that has passed since these ponds were
closed, EPA has determined that the RCRA closure requirements are neither applicable nor relevant and
appropriate for CERCLA actions in these areas. The FS alternatives for these areas were designed to
reduce infiltration, prevent incidental ingestion, reduce exposure to radiation, and minimize maintenance.
Pond 8S
Pond 8S is a RCRA regulated unit and was the last unlined pond at PMC. Early Rl sampling data
indicated that this pond was a major contributor to ground water contamination with a release rate of 15.3
gallons per minute. In October 1993, a time critical removal under the CERCLA program for removal
of the hydraulic head and interim capping was initiated by FMC as a result of an EPA Action
Memorandum. The primary goal of the time critical removal was to reduce the hydraulic loading of the
waste to reduce the movement of arsenic, selenium, nitrate, gross alpha, fluoride, manganese and
phosphorus into the ground water. FMC proceeded with dewatering the waste, filling the pond with sand
and slag, and installation of an interim cap to achieve this goal. At that time, capping of the pond with
wastes in place was selected for two reasons: (1) proven technologies to deactivate the waste in a large
surface impoundment of this type did not appear to be available, and (2) the continued input of
contaminants to ground water warranted immediate action. FMC proceeded with dewatering the waste
and installation of an interim cap to achieve this goal. Final closure of this pond must be conducted in
accordance with the requirements at 40 CFR Part 265 Subpart G, which requires not only short term
reduction of risks, but also action to: (1) minimize maintenance and (2) control, minimize or eliminate
releases to the extent necessary to protect human health and the environment after closure has been
completed. Closure of this pond was managed by the CERCLA program up until 1997 when the RCRA
program took the lead for the final cap design.
5.0 SUMMARY OF SITE CHARACTERISTICS
Between 1991 and 1996, an RI/FS was performed to determine the nature and extent of contamination
at the site and provide sufficient data for the risk assessment. Using the results from previous
investigations and knowledge of the site, FMC and Simplot developed a sampling plan for
collecting/analyses of surface and subsurface soils, ground water, surface water, sediment, plants and
animals, and air. In addition, ground water modeling, air modeling,and sampling of FMC and Simplot
products and by-products were conducted to develop a comprehensive understanding of the source and
fate of site contaminants. Details of these investigations are provided in the Rl report.
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The major characteristics of the site and the nature and extent of contaminant releases are summarized
below by environmental media:
5.1 Geologic Setting
The EMF Site is located at the juncture between the Basin and Range physiographic province to the
south and the Snake River Plain to the north. The EMF Site is at the base of the northern slope of the
Bannock Range and extends onto the southeastern margin of the Michaud Flats.
The Michaud Flats is a portion of the Snake River Plain to the north and west of Pocatello, Idaho. The
Michaud Flats is a roughly elliptical area about nine miles long and five miles wide, bounded to the west
by Bannock Creek, to the north by American Falls Reservoir, to the east by the Portneuf River, and to
the south by the Bannock Range.
The stratigraphy of the Site area can be generally described as discontinuous layers of unconsolidated
sediments deposited on an erosional surface that was incised in volcanic bedrock. The sedimentary unit
immediately above the bedrock is a gravel derived from volcanic rocks. Overlying the gravel is varying
thicknesses of fine-grained silts, clays, and sands that form a discontinuous, semi-confining unit. The
fines are overlain by another coarse-grained unit, called Michaud Gravel, that consists of quartzite, chert,
and volcanic gravel, cobbles, and boulders (see Figure 4). Above the second gravel unit is a finer-
grained unit that consists of interfingered silts, clays, and sands. In the western part of the EMF Site
area, a separate but discontinuous third coarse-grained layer is present. Deposits of windblown silt
(loess) and a colluvial silt layer of variable thickness mantle the study area. The loess layer ranges from
2 to more than 100 feet thick at the EMF facilities, and is calcareous. To the north and east of the
facilities, the Michaud Gravel occurs in scoured channels, and the fine-grained layers present in the
western and central areas of the facilities are generally absent to the east.
5.2 Hydrogeology
Within the Michaud Flats area, the aquifer system can be divided into a shallow aquifer and a deeper
aquifer. The shallow aquifer is Michaud Gravel which is typically overlain by a silt aquitard, but is locally
unconfined. Hydraulic conductivity in the shallow aquifer ranges from 30 ft/day to 1,000 feet per day.
The deeper aquifer contains the gravel and volcanics of the Sunbeam and Starlight Formations, and the
Big Hole Basalt. The deeper aquifer is the primary water-producing aquifer within the Michaud Flats Area
with a hydraulic conductivity ranging from 30 feet per day to 340 feet per day. The deeper aquifer
underlies the American Falls Lake Beds, the regional aquitard between the shallow and deeper aquifers.
Ground water that flows into the deeper aquifer system discharges to the Portneuf River (via springs and
base flow contribution), American Falls Reservoir, or to one of the numerous springs and seeps in the
Fort Hall Bottoms. Agricultural, industrial, and domestic water supply wells extract ground water from the
regional (deeper) aquifer.
The Portneuf River, which flows along the old track of the Bonneville Floods, is underlain by the very
coarse, permeable Michaud Gravel. The Portneuf River exhibits a transition near the Interstate 86 (I-86)
bridge from a losing stream in its upstream portion to a gaining stream. The gaining section of the
Portneuf River is associated with numerous springs and a large flux of ground water that occurs as base
flow.
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Ground water enters the site from the Bannock Hills south of the site and from the Michaud Flats north
and west of the site. The two flows converge and commingle beneath the FMC facility and then leave
the site, moving in an east-northeasterly direction toward the Portneuf River. Figures 8 and 9 depict the
contours of shallow and deeper ground water elevations in the vicinity of the Plants. Upon reaching the
river, the ground water that had flowed under the site either discharges to the river or meets and mixes
with a high-volume, high-velocity flow of ground water that moves down the Portneuf River valley to the
southeast of the facilities. The latter flow dilutes and carries the ground water from beneath the site in
a northwesterly direction parallel to the river channel, out into the Fort Hall bottoms northwest of the site.
Withdrawal rates for irrigation wells in the deep aquifer throughout the Michaud Flats are approximately
1,000 g.p.m. The FMC production wells have a total combined flow rate of approximately 875 g.p.m.
Extraction from Simplot production wells is about 3,300 to 4,000 g.p.m. combined flow. The Simplot and
FMC production wells are located below the American Falls Lake Bed (AFLB) and create cones of
depression in the deeper aquifer. When the FMC and Simplot plants cease operations and no longer
extract ground water most of this extracted ground water will discharge to the Portneuf River. It is
currently unclear what effect cessation of pumping would have on ground water contaminant
concentrations and migration.
5.3 Surface Water Hydrology
Major surface water features of the region include the Snake River, Portneuf River, and the American
Falls Reservoir. The reservoir is an impoundment of the Snake and Portneuf Rivers and Bannock Creek.
among others; both rivers discharge into the reservoir at its east end.
The Portneuf River flows from southeast to northwest through the region and passes northeast of the
Simplot Don Plant. Michaud Creek passes the FMC facility to the west. Surface water in the EMF study
area also includes numerous springs and associated spring drainage channels along the Portneuf River.
5.4 Climate
The EMF region climate is semi-arid, characterized by a wide range of temperatures. The warmest
temperatures generally occur from June through August (daily mean maximum temperature 84.1 °F), and
the coldest temperatures occur from December through February (daily mean minimum temperature of
17.8°F). The highest and lowest ternperatures-recorded at the Pocatello Municipal Airport were 104°F
in August 1969, and minus 33°F in February 1985, respectively.
The annual mean precipitation for the region is 10.86 inches per year, with the greatest amount of
precipitation occurring during the spring. The mean potential evaporation is 29.76 inches for the 3-month
summer period and 3.36 inches for the winter months. The area! and seasonal distribution of
precipitation also influences hydrogeologic characteristics. Precipitation patterns in this region are
strongly linked to topography, with larger amounts of snow and overall precipitation falling at higher
elevations. The higher elevations (i.e., the Bannock Range and Pocatello Range) serve as recharge
areas for aquifers in the valleys.
The prevailing wind direction is from the southwest; however, a strong secondary flow emerges from the
Portneuf River valley, particularly under valley wind conditions. It then flows past the site and moves out
into the flats to the northwest. In addition, the air monitoring results and the surface soil concentration
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patterns suggest that the complex terrain at the site can produce wind patterns that carry appreciable
amounts of site-related contaminants to the west-southwest, the prevailing upwind direction, at least as
far as the Michaud Creek area. The annual average wind speed is 10.2 miles per hour (mph), though
the area occasionally experiences stagnation conditions, particularly during the winter months.
The combination of the arid climate, strong winds that can mobilize fugitive dust from unprotected soils,
stagnant conditions that can trap airborne contaminants, and air pollution sources, including the site and
other sources, has resulted in airborne contaminant concentrations that occasionally have exceeded
acceptable levels. This has lead to the Pocatello area being designated a PM10 nonattainment area.
5.5 Ecosystems and Species of Concern
A variety of habitats and vegetation exist in the vicinity of the site as shown in FIGURE 13. There are
also a number of species of concern in the vicinity of the EMF Site. A complete discussion of ecosystem
types and wildlife is provided in the Ecologic Risk Assessment, which also includes identification and
discussion of listed species and designated wetlands.
Native upland ecosystem characteristic of the semi-arid temperate climate of southeastern Idaho is
prevalent in the site area. The high plateau of the Michaud Flats and the foothills of the Bannock Range
support sagebrush steppe communities dominated by sagebrush and a variety of other shrubs and
grasses. This community is replaced with juniper woodlands and cliff/cave/canyon communities at higher
elevations. Extensive cultivated agricultural areas are also located near the site, comprising
approximately 40% of the EMF Site area.
Wildlife typical of sagebrush steppes is abundant in the site area and includes small mammals such as
the deer mouse, large herbivore such as the mule deer, carnivores such as the coyote, raptors such as
the red-tailed hawk, gallinaceous game birds such as the sage grouse, and numerous species of
songbirds.
Aquatic and wetland communities are well-developed in the site vicinity. According to the National
Wetland Inventory (NWI) maps of the United States Fish and Wildlife Service (USFWS), the Portneuf
River channel, the river's associated riparian corridor, and the Fort Hall Bottoms are designated wetlands.
Other wetlands include areas along Michaud Creek and other locations. The Portneuf River supports
an extensive riparian community dominated by willow, red-osier dogwood, and other scrub/shrub riparian
vegetation. This riparian zone is an important source of food, cover, and nesting sites for many wildlife
species such as songbirds and piscivorous birds. The riverine, open-water, and mudflat habitats of the
Portneuf River and American Falls Reservoir are significant nesting and wintering habitats for waterbirds.
Thousands of individuals of numerous migratory bird species use areas in and near the site, particularly
the Fort Hall Bottoms. Common species of migratory birds include waterfowl such as ducks, geese, and
swans; colonial birds such as pelicans, herons, shorebirds, and gulls; and raptors.
Eleven species of concern listed as endangered, threatened, and rare are reported to occur in the site
area. The bald eagle and the orchid Ute Ladies'-tresses are listed as threatened and the peregrine falcon
is listed as endangered under the Endangered Species Act. A wintering population of bald eagles is
listed by the State of Idaho and by the USFWS as endangered in Idaho. The remaining species of
concern are identified as State of Idaho Special Concern species and/or are identified as federal
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Category 2 species, which indicates they are being considered for listing as a threatened or endangered
species.
5.6 Key Remedial Investigation Findings
Phosphate ore is the primary raw material for both the FMC and Simplot facility operations.
Contaminants identified through Rl sampling and analysis of environmental media are primarily linked
to constituents of the phosphate ore and sulfur and nitrogen which is used in the Simplot process. Table
2 shows the ratios of concentrations of constituents in phosphate ore relative to local background soils.
No contamination was found to be associated with the relatively small amounts of reagents, catalysts and
fuels used by the facilities. Therefore, the feasibility study focused on the various phosphate ore-based
products, byproducts, wastes, and emissions for each facility.
The primary constituents of the phosphate ore are calcium, phosphorus and fluoride. The ore also
contains trace concentrations of other elements including antimony, arsenic, beryllium, boron, cadmium,
chromium, copper, Lead-210, mercury, molybdenum, nickel, selenium, silver, thallium, uranium-236,
vanadium, and zinc. Key findings pertaining to the nature and extent of contamination, source
contribution, and contaminant fate and transport are summarized below for each environmental medium.
5.6.1 Soils and Solids
During the Rl both surface and subsurface soil samples were collected over a large area of the site.
Figure 16 shows the surface soil sampling locations. A number of factors have contributed to the soil
contamination patterns observed at the site:
• Raw materials and waste materials have been deposited at various locations at
both Plants;
• Old wastewater storage and treatment ponds that contained settled solids have
been closed and regraded, with the settled solids left in place in some cases;
• Waste materials, mainly slag and gypsum, have been used extensively as fill and
to surface roadways;
• Infiltration of wastewater has carried contaminants down into subsurface soils
beneath the gypstack and at the locations of unlined ponds where sustained
hydraulic heads existed; and
Airborne contaminants have been deposited on the ground surface.
The key Rl findings with respect to nature and extent of EMF Site-related Contaminants in soils are as
follows:
Soil Contaminants of Concern (COCs) are principally derived from phosphate ore, which
contains phosphorus, fluoride, arsenic, beryllium, cadmium, chromium, vanadium, zinc,
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uranium-238 (and its decay products) and other elements. The frequency of detection
of contaminants in soils at the site, are shown in Tables 3 and 3A.
Although the presence of phosphate ore-based products, byproducts and waste materials
are common within the FMC and Simplot Plants, the Contaminants in these materials are
not prone to migrate to underlying soils and ground water in areas where a sustained
hydraulic head does not exist.
The underlying soils at the facilities have been contaminated primarily in those areas
where a sustained hydraulic head was or is present, or where materials have been
integrated into the fill.
Deposition of airborne materials such as cadmium, fluoride, radium, and zinc has occurred
in the Plant and Off-Plant Areas since the Plants began operation. Underlying soils have
not been influenced in the Off-Plant area. Figures 17 and 18 depict the cadmium and
fluoride concentrations in surface soils.
• The radionuclides of potential concern at the EMF site are natural uranium (U-235 and U-
238) and thorium, which originated as constituents of the phosphate ore processed at the
site, and daughter radionuclides produced by the disintegration of the uranium and
thorium. However, because U-238 is much more abundant in the ore than U-235 or
thorium, U-238 and its daughters appear to be the radionuclides of greatest concern at
the EMF site. Table 4 shows the locations where gross alpha activities were measured
above the soil screening level (based on 41 pCi/G soil gross alpha activity and 4pCi/l
radon level) in subsurface soil at Simplot (a comparable table was not available for FMC).
• The native soils at the site are generally alkaline (pH of 7 or higher) because of their
calcareous nature. This is consistent with most soils in the arid regions of the western
United States. This is significant, as alkaline soils tend to retain metals and prevent their
migration through soil horizons to ground water.
5.6.2 Ground water
During the Rl, approximately 77 monitoring wells were installed which are shown in Figure 19. Ground
water within the FMC and Simplot Plants flows generally north and northeast from the facilities and is
either captured by facility production wells in the lower aquifer or flows northward along a relatively
narrow path to eventually discharge to springs/river north of I-86.
Ground water flow from the facilities (i.e., containing EMF-related Contaminants) is small in comparison
with the flux in the regional or deeper aquifer. The combined shallow aquifer flux from the EMF facilities
was calculated from the Rl flow model as 4.5 cfs. This discharge is only about 20 percent of the total
calculated flow in the shallow aquifer from all sources (21 cfs) and a very small fraction of the estimated
average ground water discharge to the Portneuf River in the gaining reach north of the Simplot facility
(approximately 200 cfs).
The key Rl findings with respect to nature and extent of EMF Site-related Contaminants in ground water
are as follows:
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• Contaminants have been released to ground water throughout the FMC and Simplot Plant
areas. Contaminants that have been measured in the ground water at levels above the
Safe Drinking Water Act Maximum Contaminant Levels (MCLs) include the following:
antimony, arsenic, barium, beryllium, cadmium, chromium, copper, lead, mercury, nickel,
selenium, thallium, gross alpha, and gross beta (Table 5 provide a summary of the
ground water analytical results at the site). These concentrations decline with increasing
distance from the Plants and meet MCLs in the Off-Plant area (see Figure 20 depicting
arsenic concentrations in the shallow aquifer throughout the plant areas). Current
evidence suggests that the area of ground water contamination is not expanding and
contaminant concentrations are not increasing.
• Contaminants have been primarily transported to the shallow ground water system
underlying the facilities from unlined impoundments and ponds. At sources where there
is no sustained hydraulic head, downward migration of contaminants is limited. The
contaminants transported by this process are mainly monovalent cations such as sodium,
potassium, and lithium; metals and transition elements capable of forming oxyanions such
as arsenic, boron, phosphorus, selenium, sulfur, and vanadium; and, soluble anions such
as chloride.
The predominant mechanisms controlling contaminant concentrations in ground water are
attenuation in the vadose zone and advective mixing, where the EMF Site-influenced
shallow aquifer flow merges with the large volume of ground water flowing through the
Michaud Flats and Portneuf River ground water systems (see Figure 21 showing the
ground water flow at FMC). Although slightly elevated concentrations of contaminants
were detected in the upper portion of the deeper aquifer near source areas, in most areas
ground water movement is upward from the deeper aquifer to the shallow aquifer, thereby
limiting the downward migration of contaminants to the deeper aquifer.
Shallow ground water from the Simplot and FMC Plants discharge to the Portneuf River.
However, there does not appear to be any measurable effect on surface water quality
downstream of the discharge attributable to the Plants other than small increases in some
major ion concentrations.
5.6.3 Surface Water/Sediments
There are no active water courses within the Simplot and FMC Subareas. Runoff is controlled in these
areas and evidence of recent erosion is not present. The process operations of the facilities are for the
most part a closed loop, and the only active surface discharge to the Portneuf River is the Industrial
Waste Water (IWW) ditch which carries cooling waters from FMC operations. The key Rl findings with
respect to nature and extent of contamination, source contribution and Contaminant fate and transport
in surface water/sediments are as follows:
The primary migration pathway for contaminants to surface water is via ground water
discharge to the Portneuf River and adjacent springs.
Although contaminants from the site do enter the surface water pathway through the
ground water pathway, the contribution is negligible in terms of concentration and load
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EXPLANATION
SMtoo AQ4Ur Honkoi w«l
-' ^/ Simplot Subarea
CenKxn ««• tmad on nwan eenonntioni in thaDoiriMli.
UroaonOTtntim WOT calcUiM using EPA RAQS methods.
For ml nuiiw*. *•» figur* 1.4-3.
SCALE
EASTERN MICHAUD FLATS
POCATEU.O. IDAHO
FEASIBIUTY STUDY
ARSENIC CONCENTRATIONS
IN SHALLOW AQUIFER
FIGURE 1-0
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compared to the loads from the river upgradient of the site and the influx of nonsite influenced ground
water.
The IWW ditch is the only active surface water discharge from the facilities. Samples from
a boring on the bank of the ditch showed elevated levels of several COPCs. A grab
sample of water in the ditch taken in 1992 contained elevated levels of selenium, gross
alpha, orthophosphate, fluoride, and several other parameters. Subsequent sampling in
July 1993 showed the water in the ditch met drinking water standards. FMC attributed
the elevated concentrations in 1992 to a plant upset.
Erosion of soils containing site related contaminants and air deposition of contaminants
on the Portneuf River were not found to be significant transport pathways to surface
water.
• Four trace elements detected in surface water were selected for being of potential
concern to aquatic and semiaquatic biota - mercury, selenium, silver, and vanadium.
Elevated levels of these COPCs were detected at various springs and Portneuf River
locations.
• COPCs in sediments include: cadmium, fluoride, mercury, and selenium because of their
potential toxicity to fish and wildlife and tendency to mobilize in the aquatic food chain.
Cadmium in particular was found to be 2.5 times higher in the Portneuf River Delta at the
Fort Hall Bottoms than at a similar location on the Snake River.
5.6.4 Air
The region is an arid zone with varying topography. Regional air movement is generally from the
west/southwest, with localized wind flow patterns controlled by the topography. The EMF Site is located
in a nonattainment area for PM10 During the Rl an air monitoring program was set up with seven
monitoring locations around the site. These locations are shown in Figure 22. The key Rl findings with
respect to air are as follows:
During the Rl, airborne contaminant concentrations were measured at seven locations
around the site for up to one year. The highest concentrations of all of the COPCs, except
lead-210, were found at Station 2, which was located just outside the FMC fence line,
south of Highway 30.
Concentrations of arsenic, cadmium, total chromium, total phosphorus, lead-210.
polonium-210, thorium-230, and uranium were observed above regional background
levels. Table 6 provides a summary of the air analytical results.
• Ambient air concentrations of contaminants decline beyond the FMC and Simplot Plant
boundaries.
Over the last several years, major changes in ore handling at the Simplot Plant and other
operational changes at both Plants have reduced airborne emissions.
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More recent air monitoring data collected by the EPA and Shoshone Bannock Tribe show
that maximum paniculate emissions from the Plants may be as much as three times
higher than maximum values measured during the Rl and recent average values are
approximately 50% higher than that measured during the Rl.
5.6.5 Terrestrial and Aquatic Investigations
Due to the minimal contact and use of the Plant areas by wildlife, the focus of the risk assessment was
on ecosystems in the Off-Plant areas. The key findings of the ecological investigations are as follows:
Detailed ecological investigations of the EMF Site were conducted in September and October of 1994.
to provide site-specific, supplementary data for the ecological risk assessment. Uptake of COPCs in
terrestrial food chains was investigated by chemically analyzing co-located samples of soil, sagebrush,
grass (thickspike wheatgrass), and small mammals (deer mouse) in sagebrush-steppe habitats, and
co-located samples of soil and shrubs (Russian olive) in riparian habitats. The nature and extent of
sediment contamination was investigated in depositional areas of the Portneuf River delta at the
American Falls Reservoir. Samples were chemically analyzed for cadmium, fluoride, zinc and other
contaminants. Laboratory toxicity testing was conducted by the Companies with contaminated sediment
collected from the Portneuf River at the IWW outfall. All sampling activities were statistically designed
to allow comparison of site-related contamination with unaffected reference areas.
The results of the aquatic investigations demonstrated that cadmium is elevated approximately 2.5 times
background in depositional sediments of the Portneuf River delta (see Table 7). However, the chemical
analysis showed that the majority of cadmium is strongly bound to sediments and, thus, is not in a
bioavailable form. In addition, based on the Company study2 sediment from near the IWW outfall was
not toxic to laboratory test species of selected benthic invertebrates. Moreover, no other contaminants
were found in Portneuf River delta sediment at levels significantly above background or levels of concern.
Therefore, potential risks of adverse effects of sediment contamination on benthic life are expected to
be minimal.
The results of the terrestrial ecological investigations for soil, vegetation, and deer mice as compared to
background are summarized in Tables 8-10. The results demonstrate that cadmium, fluoride, and zinc
are elevated in riparian and upland soils and in plant tissue samples, and that cadmium and fluorides are
elevated in small mammal tissue samples collected near the site. Fluoride concentrations in vegetation
appeared to be related to current fluoride emissions which are deposited on plant surfaces and absorbed
in gaseous form by plants. There was no correlation between fluoride concentrations in soil and fluoride
concentrations in vegetation.
In general, the data confirm that the mobility of cationic metals such as cadmium and zinc is limited by
the arid, high-pH soils of the site vicinity. Hence, concentrations of COPCs are much reduced in the
terrestrial food chain compared with their concentrations in soil. In addition, it is likely that soil
contamination at the site is confined to the surficial soil horizon.
2 While this study was conducted independently by the Companies without direct EPA
oversight previous studies of benthic life in the Portneuf River confirm the findings.
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6.0 SUMMARY OF SITE RISKS
CERCLA response actions at the Eastern Michaud Flats site as described in this ROD are intended to
protect human health and the environment from current and potential future exposure to hazardous
substances found at the site.
To assess the risks posed by site contamination, a "Baseline Human Health and Ecological Risk
Assessment," (Risk Assessment) was prepared by E&E, a contractor to EPA. The Risk Assessment
assumes that there is no site cleanup.
6.1 Human Health Risks
6.1.1 Approach to Human Health Risks
An assessment of the risks to human health involve a five-step process: identification of contaminants
of potential concern (COPCs), an assessment of contaminant toxicity, an exposure assessment for the
population at risk, quantitative characterization of the risk, and an analysis of uncertainty.
6.1.2 Conceptual Site Model
Individuals potentially exposed to site-related contaminants include current and potential future site
workers and nearby residents. Figure 23 shows the conceptual site model for human exposure. The
principal current and/or potential future exposure pathways are:
• Inhalation of airborne contaminants;
• Dermal contact with, and incidental ingestion of, contaminated soils and waste
materials;
• External radiation exposure from contaminated soils and waste materials;
• Ingestion of homegrown produce grown in contaminated soils (risks estimated
based on uptake of contaminants by plant roots;
• Use of contaminated ground water as a source of drinking water; and
Ingestion and dermal contact with contaminated surface water and consumption
of fish from those waters.
Both the FMC and Simplot Plants are operating facilities enclosed by perimeter fences with controlled
access. Normally, only Plant employees and authorized visitors can gain access to the facilities.
Trespassing may be possible, but trespassers have rarely been seen at either Plant. Together, the two
Plants currently employ approximately 1,000 people.
Under current conditions, individuals who experience exposure at the Plants appear to be limited to Plant
workers. Current workers could be exposed to contaminants through incidental ingestion of soils,
inhalation of contaminated air, and external exposure to gamma radiation from contaminants in soil and
waste materials. Contaminated ground water is not used as drinking water at either Plant. The FMC
35
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Plant obtains its drinking water from wells in the deep aquifer which currently meets MCLs. Employees
at the Simplot Plant use bottled water.
Residents living around the site are the individuals likely to experience the greatest exposures to site-
related contaminants in the Off-Plant areas. Currently, the nearest residence is approximately 1/4 mile
north from the FMC Plant Area (see Figure 24 for the existing residential areas). Site-related
contaminants are found in surface soils throughout much of the site as a result of the migration and
deposition of airborne particles. Residents could be exposed to site-related contaminants by breathing
contaminated air, through incidental ingestion of contaminated soil, and by exposure to gamma radiation
from radionuclides deposited on the soil. In addition, many residents of the area consume homegrown
produce, and some consume homegrown beef. Currently, there are no residences in areas where
ground water has been contaminated by the site. Therefore, use of ground water as drinking water is
not a complete exposure pathway for current residents of the site, but it could be a potential future
exposure pathway if existing wells affected by site-related contamination were returned to service, if new
wells were installed in the contaminated area, or if the plume were to expand or shift and thereby affect
presently unaffected existing or future drinking water wells.
6.1.3 Background Concentrations
Many of the metals, other inorganic chemicals, and radionuclides that constitute the principal
contaminants'at the site also are natural constituents of soil, ground water, surface water, and sediment.
Therefore, it was necessary to determine what the natural background concentrations were in the various
media in order to determine whether concentrations measured in samples were consistent with natural
levels or due to contamination! For soils, background values were obtained by determining the 95th
percentile concentration of local subsurface soils. Ground water background values were determined
from the 95th percentile concentration in wells determined to be either hydrological upgradient or cross
gradient from potential site-related contamination sources and free of site related influences. For air,
background was obtained from determining the 95th percentile from air monitoring data collected at
Station 6 (background location).
6.1.4 Contaminants of Potential Concern
An initial screening analysis was done, using information available at the time, to identify the
contaminants of potential concern (COPC). This screening involved two steps. In the first step,
contaminants were selected based upon a very conservative estimate of potential health risk. Maximum
concentrations of chemicals in media (e.g., soil, air, and ground water) at the site were compared to
conservative risk-based concentrations. These risk-based concentrations were derived using standard
EPA exposure assumptions assuming residential exposures in the Off-Plant area and industrial
exposures for the Plant Areas; acceptable cancer risk levels of 1x10'7 for soil and 1x10'6 for water; and
acceptable HQs of 0.1. Tables 11-13 show the screening criteria for soils, ground water, and air,
respectively.
The second step in the selection of COPCs was a more refined screening which narrowed the list of
COPCs by considering factors such as frequency of occurrence of each COPC, detection limits, and
background concentrations for inorganics only.
36
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N
SOIL SAUPUNG LOCATION
AND DESIGNATION
AIR MONITORING STATION
LOCATION AND DESIGNATION
O APPROXIMATE BOUNDARY
OF RESIDENTIAL AREA
SCALE
1 T .. .
1600 0 1600 FEET
EASTERN MCHAUD FLATS
POCATEU.O. DAHO
FEASBLTTY STUDY
EXISTMC RESDEHTVU. AREA AND
SAMPLMG LOCATIONS USED M
THE BASELME RISK ASSESSMENT
I FIGURE 1+
-------
The list of COPCs3 for soil. air. and ground water developed for the Risk Assessment are shown in Table
14. The potential for these COPCs to impact health was further evaluated using more realistic and site-
specific exposure assumptions.
6.1.5 Toxicity Assessment
The toxicity assessment presents the toxicity data for the COPCs at the EMF site and provides an
estimate of the relationships between the extent of exposure to the COPCs and the likelihood and/or
severity of potential adverse health effects. The EMF site has both chemical and radiological
contaminants that exert their lexicological effects in different ways and require different assessment
approaches.
Toxicity information is provided in the Risk Assessment for the COPCs. Generally, cancer risks are
calculated using toxicity factors known as slope factors (SFs), while noncancer risks are assessed using
reference doses (RfDs). Tables 15-17 show the toxicity values for carcinogens, noncarcinogens, and
radionuclides.
6.1.5.1 Quantitative Indices of Toxicity
Quantitative indices of toxicity were compiled for the dose-response assessment that was used in
estimating the relationship between the extent of exposure to a contaminant and the potential increased
likelihood and/or severity of adverse effects.
The following EPA sources were used to obtain toxicity values:
• The Integrated Risk Information System (IRIS) computer database. This is the
preferred source of toxicity values because these data are the most recent EPA
criteria available and have been reviewed extensively by EPA;
• The Health Effects Assessment Summary Tables (HEAST). These tables were
consulted if a toxicity value was unavailable on IRIS. EPA's Environmental Criteria
and Assessment Office (ECAO) established these values for use in risk
assessments; and
EPA's Environmental Criteria Assessment Office.
EPA developed Slope Factors (SFs) for estimating excess lifetime cancer risks associated with exposure
to potential carcinogens. SFs are expressed in units of (mg/kg-day)"1 and are multiplied by the estimated
intake of a potential carcinogen, in mg/kg-day, to provide an upper-bound estimate of the excess lifetime
cancer risk associated with exposure at that intake level. The term "upper-bound" reflects the
conservative estimate of the risks calculated from the SF. Use of this approach makes underestimates
of the actual cancer risk highly unlikely. SFs are derived from the results of human epidemiological
3 Other contaminants may be added to this list if new analytical methods become available
(such as for P4) or new information indicates other contaminants pose a potential risk.
38
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Table 14
SUMMARY OF COPCs BY MEDIA
Chemical
Aluminum
Antimony
Arsenic
Beryllium
Boron
Cadmium
Chromium
Crystalline Quartz
Fluonde
Gross alpha
Gross beta
Lead-210
Manganese
Mercury
Nickel
Nitrate
Phosphorus
PM10
Pokxuum-210
Potassium-40
Radium- 226
Radon
Selenium
Silver
Tetrachloroethene
Thallium
Thorium-230
Trichloroethene
Uraniunv234
Uranium-238
Vanadium
Zinc
Soil
X
X
X
X
X
X
X*
xa
X
X
X
X
X
X
•
*.c
X
X
t
X
a
X
X
X
Groundwater
X
X
X
X
X"
x'
X
X
X
X
«.
•
•
X
X
X
•
X
•
*
X
X
Air"
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
. individual radionuclides potentially responsible for elevated gross alpha and grass beta levels are also COPCs.
Chemicals that exceeded background concentrations and lacked inhalation loxicrty criteria (reference concentrations
and inhalation unit risks) were retained as COPCs.
Retained as a COPC mainly for evaluation of potential radon infiltration into buildings under alternate future commercial
or industnal uses of the site.
COPC = Contaminant of potential concern.
-------
studies, or chronic animal bioassay data, to which mathematical extrapolation from high to low doses.
and from animal to human studies, have been applied.
EPA developed Reference Doses (RfDs) to indicate the potential for adverse health effects from
exposure to chemicals exhibiting noncarcinogenic effects. RfDs, which are expressed in units of mg/kg-
day, are estimates of lifetime daily exposure for humans, including sensitive subpopulations likely to be
without risk of adverse effect. Estimated intakes of contaminants of concern from environmental media
(e.g., the amount of a contaminant of concern ingested from contaminated drinking water) can be
compared to the RfD. RfDs are derived from human epidemiological studies or animal studies to which
uncertainty factors have been applied.
6.1.5.2 Combining Radionuclide and Chemical Cancer Risks
The methods used by EPA for estimating cancer risks from exposure to chemical and radionuclide
carcinogens are similar in their general approach, but differ significantly in some of their details. One
important difference is in the way toxicity values (i.e., SFs) were developed. For both radionuclides and
chemical carcinogens, SFs are obtained by extrapolating from experimental and epidemiological data.
However, for radionuclides, human epidemiological data usually form the basis of the extrapolation, while
for many chemical carcinogens, laboratory experiments are the primary basis of the SF extrapolation.
Another even more fundamental difference between the two is that SFs for chemical carcinogens
generally represent an upper bound or 95% confidence limit value, while radionuclide SFs are best
estimates or central tendency values. In light of these differences, the two sets of risk estimates are
tabulated separately in the risk assessment.
6.1.6 Exposure Assessment
The exposure assessment characterizes the exposure scenarios, identifies potentially exposed
populations and their exposure pathways and routes of exposure, and quantifies exposure in terms of
chronic daily dose (mg/kg/day or milligrams of contaminant taken into the body per kilogram of body
weight per day). EPA Superfund guidance recommends that both RMEs (reasonable maximum
exposures) and average exposures be calculated in site risk assessment. RME exposures are calculated
using assumptions that result in higher than average exposures to ensure that the risk assessment
results are protective of the reasonably maximally exposed individual. For this risk assessment, RME
and average exposures (identified as the central tendency (CT)) were quantified by using Region 10 EPA
default exposure factors (e.g., body weight, contact rate, exposure frequency and duration) with site-
specific exposure point concentrations.
Exposure and risk estimates were calculated for all of the chemicals and radionuclides selected as
COPCs for an environmental medium for every sampling location using the 95% Upper Confidence Limit
(UCL) of the arithmetic mean of the concentrations measured at those locations. Because some of the
concentrations of some of the COPCs were at or close to background levels at many of the locations
evaluated, the exposures and risk associated with background concentrations also were calculated for
each exposure scenario for comparison.
For workers, only RME exposures were calculated since default exposure factors were not available.
For residents site-specific information was used in estimating intake factors for consumption of
homegrown produce. Potential residential exposures from the other pathways were estimated using
40
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EPA's standard default exposure factors. Categories of workers selected for the risk assessment and
the exposure factors used in the risk assessment were based on information provided by PMC and
Simplot.
6.1.6.1 Alternate Future Uses of the FMC and Simplot Plants
Both Plants are currently expected to continue operations for the foreseeable future; however, one or
both plants could cease operations and be converted to an alternate use. Because of the industrial
nature of the plants and the large amount of waste materials at the facilities, future residential use of the
Plant areas was considered unlikely. A more likely future use would be some alternate commercial or
industrial use. Under such a future use scenario, a worker at the redeveloped site would probably have
the greatest potential exposure to site contaminants. Accordingly, the potential exposure of a
hypothetical future site worker was evaluated to assess the risks the Plant area could pose in the future
if it were to be converted to a different use. The exposure pathways for the hypothetical future plant
worker were assumed to be the same as those for current workers, with two additions. Because the site
is not served by a pu! 'ic water supply system, ground water might be used as a source of potable water,
in which case future plant workers could be exposed to contaminants in ground water. In addition, during
Plant redevelopment, new buildings could be constructed in areas having elevated levels of radio-
nuclides in the soil. Workers using such buildings could be exposed to elevated levels of radon in indoor
air that infiltrated the buildings from the adjacent soil.
6.1.7 Risk Characterization
For carcinogens, risks are estimated as the incremental probability of an individual developing cancer
over a lifetime as a result of exposure to the specific carcinogen. Excess lifetime cancer risk is calculated
by multiplying the SF (see toxicity assessment, section 6.1.2) by the quantitative estimate of exposure,
the "chronic daily intake." These risks are probabilities generally expressed in scientific notation (e.g.,
1x10"*). An excess lifetime cancer of 1x10 indicates that an individual has a one in one million
(1:1,000,000) chance of developing cancer as a result of site-related exposure to a carcinogen under the
specific exposure conditions assumed.
The potential for noncarcinogenic effects is evaluated by comparing an exposure level over a specified
time period (lifetime) with a RfD (see toxicity assessment section above) derived for a similar exposure
period. The ratio of exposure to toxicity te called a hazard quotient (HQ). Hazard quotients are
calculated by dividing the exposure by the specific RfD. By adding the hazard quotients for all COPCs
that effect the same target organ (liver, nervous system, etc.), the hazard index (HI) can be calculated.
The RME provides a conservative but a realistic exposure scenario for considering remedial actions at
a Superfund site. Based on the RME, when the excess lifetime cancer risk estimates are below IxlO'6,
or when the noncancer HI is less than 1, EPA generally considers the potential human health risks being
below levels of concern. Remedial action may be warranted when excess lifetime cancer risks exceed
1x10"* (one in ten thousand) and His exceed 1.0. Between 1x10* and 1x10"*, clean up may or may not
be selected, depending on individualsite conditions including human health and ecological concerns.
The following discussion summarizes the cancer and noncancer risk characterization results for the
Eastern Michaud Flats Superfund site.
41
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6.1.7.1 Residential Areas
6.1.7.1.1 Near Plant Areas
As discussed earlier, an area north of the FMC and Simplot fence lines was evaluated in the risk
assessment for possible residential use. Because of its proximity to the Plants, it seems unlikely that
any residences would be constructed there in the future. In addition, most of the land in this area is
owned by FMC or Simplot, and deed restrictions barring residential use have already been or will be
placed on these parcels. Nevertheless, all of the residential exposure pathways in this area have
potential Incremental Carcinogenic Risks (ICRs) and HQs substantially above benchmark levels (cancer
risk of 1x10* or a HQ quotient of 1) in the Northern areas of the FMC and Simplot plants and south of
1-86, and the exposure point concentrations are all well above background levels. The highest potential
cancer risks are for external radiation exposure from soils (ICRs from 4.5x10"* to 4x10°) and potential
use of contaminated ground water as drinking water (chemical ICRs - 1.7x10^ to 9.5x10"* due to arsenic;
rad ICRs - 1.5x10^ to 9.5X10"5 due to lead-210. estimated from gross alpha). The ICRs for inhalation of
airborne contaminants are also elevated in this area (Air Monitoring Station 2: chemical ICR - 1.5x10"5
due to cadmium, chromium (VI), and arsenic; rad ICR - 6.0x10'5 due to polonium-210).
6.1.7.1.2 Existing Residential Areas
In the existing residential areas, shown in Figure 24, the incremental radiological cancer risks for the
exposure pathways arising from soil are due mainly to external radiation exposure and, for the RME case,
fall between 1x10"* and 1x10* throughout much of the area. Table 18 summarizes the radionuclide
cancer risks in existing residential areas and Table 19 summarizes the radiological carcinogenic risks to
residents from soil and vegetation. At some locations the exposure point concentrations are comparable
to background levels, but at the locations with the higher ICRs the exposure point concentrations are at
least 1.5 times background levels. Figures 25-27 show Off-Plant areas were radionuclide activities
exceed 1x10"* to 1x10/6 incremental risks.
The incremental chemical cancer risks from the soil pathways range from about 1x10"* to 8.4x10^ and
are mainly due to arsenic. Table 20 summarizes the chemical cancer risks in existing residential areas.
The exposure point concentrations giving rise to these risks are comparable to background levels at most
locations, but the locations with the higher ICRs have exposure point concentrations 1.5 to 2 times
background.
IHQs exceed 1 for the residential soil pathways for antimony, boron, cadmium, fluoride, mercury,
vanadium, and zinc. Table 21 summarizes the noncarcinogenic risks to residents from soil and
vegetation. The IHQs for cadmium are substantially above 1 at several locations (see Figure 28). The
exposure point concentrations of cadmium are due to consumption of homegrown produce.
New information on the quantities of homegrown produce items consumed became available after the
HHRA for the EMF site was completed. This information lead EPA to reevaluate the estimates of
exposure to site-related contaminants from consumption of homegrown produce and the associated risks.
The revised consumption rates, which are approximately 2 to 3 times lower than the original estimates,
are believed to more realistically reflect the actual quantities of homegrown produce items likely to be
consumed by residents of the Pocatello area. Only the estimated cadmium exposures were quantitatively
reevaluated because cadmium was the only COPCs for which the IHQs for this pathway exceeded 1 in
42
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existing residential areas. The estimated exposure to the other COCs would also change in proportion
to the estimated changes in the cadmium exposures. Revised estimates of the incremental hazard
quotients for cadmium exposure from consumption of homegrown produce are reflected in Table 22. In
the existing residential areas around the site, IHQs for cadmium exposure via this pathway are highest
in residential areas 1,2.4, and 6 north of the site, where IHQs for reasonable maximum exposure range
from approximately 0.7 (in area 4, southwest of Siphon and Philbin Roads) to approximately 1.4 (in area
1, Rowlands Dairy).
Air emissions from the site have resulted in PM10 levels that exceed the NAAQS annual average standard
for PM10 at Station 2, which was located just north of the FMC fence line, and PM10 levels that are
noticeably elevated at Station 1. The ICRs for inhalation of airborne contaminants also exceed 1x10*"
away from the immediate site area (see Table 23 for a summary of the chemical risks to residents from
inhalation). The radiological cancer risks are somewhat elevated (ICRs of 1.0x10"5 and 1.1x105) at
Stations 3 and 5, which are located near existing residences, due to exposure point concentrations of
polonium-210 that are 35% to 40% above background levels (see Table 24 for a summary of the
radiological carcinogenic risks to residents from inhalation). The chemical cancer risks slightly excsed
1x10~* at Stations 1 and 5 (ICRs of 2.2xfD and 1.1x10 ) due to exposure point concentrations of
cadmium and chromium (VI) 2 to 9 times higher than background levels. Stations 3 and 5 are located
near existing residences.
6.1.7.2 Plant Workers
Tables 25-26 summarize chemical cancer risks for workers at FMC and Simplot and Tables 27-28
summarize the radiological risks. The greatest estimated ICRs to current site workers are from exposure
to external radiation from soil and other surficial material. These risks range from 1.3x10"4 to 8.0x10"*
for the various worker categories evaluated and are 3 to 9 times higher than the risks for identical
exposures to local background soils. Incidental soil ingestion and inhalation of airborne contaminants
also have estimated ICRs great enough to be of potential concern. Both the radiological and chemical
cancer risks were of a similar magnitude for these two pathways. The incremental radiological cancer
risks range from 6.0x10* to 2.0x10*, and the chemical cancer risks range from 1.8x1$ to 8.3xfO
These risks are approximately 3 to 10 times higher than the corresponding background risks. The soil
ingestion risks are due to arsenic, beryllium, and the lead-210 and radium-226 levels estimated from the
gross alpha measurements. The inhalation risks are due to cadmium, chromium (VI), arsenic, and
polonium-210. None of the estimated IHQs for noncarcinogenic effects exceeded 1 for current site
workers. However, PM10 levels exceed the NAAQS annual average standard at Station 2, which was
used to estimate the exposure of Plant workers to airborne contaminants.
The greatest estimated ICRs to potential future Plant area workers are from inhalation of radon in
buildings that may be constructed on or near soils containing radioactive contaminants (approximately
4x10°), use of contaminated site ground water as drinking water (1.6xtD to 1.7xfO ), and external
radiation exposure from radionuclides in the soil (4.8X10"4 to 9.5x10"*). The radon risks were estimated
based on modeling which is described in Appendix D and are 7 to 8 times higher than background; the
external radiation risks are 2.8 to 4.6 times higher than background; and the potential drinking water risks,
which are due to lead-210 and radium-226 (estimated from gross alpha activities) and arsenic, are 15
to 21 times higher than background. The risks to potential future plant area workers from incidental soil
43
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ingestion and inhalation of airborne contaminants are lower but are still great enough to be of potential
concern. The sources and magnitude of these risks are similar to those for current site workers.
6.1.7.2.1 Noncarcinogenic Risks
Noncarcinogenic risks were only identified for future workers at the Plants and are shown in Tables 29
and 30. The incremental hazard quotients range from 1-14 and are due to potential ingestion of
contaminated ground water containing arsenic, fluoride, manganese, and vanadium.
6.1.7.3 Assessment of Potential Health Effects from Inhalation of Airborne Particulate Matter
Airborne particulate matter has been identified as a COPC for air at the EMF site, but its potential health
effects could not be assessed in the quantitative risk assessment because there are no quantitative
toxicological indices available for particulate matter. However, NAAQS have been established for
airborne particulate matter. Thus, the potential for adverse health effects from inhalation of airborne
particulate matter was assessed by comparing the PM10 levels measured in the EMF study area to the
NAAQS.
PM10 levels were measured at six air monitoring stations in the EMF study area and a reference location
(Station 6) located approximately 13 miles west-southwest of the site (the prevailing upwind direction)
every second day for a year beginning in October 1993. The locations of the air monitoring stations are
shown in Figure 22. Briefly, stations 2, 1, and 3 were located at increasing distances from the site in the
prevailing downwind direction. Station 4 was located at the northwestern edge of the city of Pocatello,
between the site and the city. Station 5 was located southwest of the site along Michaud Creek and is
upwind of the site under prevailing wind conditions; however, it appears to receive contamination from
the site when the wind is very light or is blowing from other directions. Station 7 was located east of the
site on the shoulder of the Bannock Hills, at a higher elevation than the other stations.
The maximum and average PM10 and TSP values recorded at each station are given in Table 31. The
NAAQSs for PM10 are: a 24-hour average of 150 ug/m3, not to be exceeded more than once per year,
and an expected annual arithmetic mean of 50 pg/m3. The concentrations of PM10 at the air monitoring
stations in the vicinity of the EMF site ranged from a minimum daily average of 0.2 ug/m3 at Station 5 to
a maximum of 150.74 ug/m3 at Station 2, which was located in the prevailing downwind direction just
across the northern fence line of FMC. The maximum PM10 concentration detected at Station 2 was the
only detected concentration that approached the 24-hour average standard of 1 50 pg/m3. The annual
concentration standard of 50 ug/m3 was exceeded only at Station 2 (55.75 ug/m3). The annual average
PM,0 concentrations measured at stations 1, 2, and 4 were approximately 60%, 200%, and 30% higher
than those at Station 6, the background station. Annual average concentrations at stations 3. 5, and 7
were comparable to the background levels.
Information on the characteristics of the airborne contaminants is discussed in the risk assessment.
Analysis of available information suggests that the elevated PM10 levels at stations 1 and 2 are due to
a combination of active emissions and fugitive dust from the Plants. At Station 2, the highest PM10 levels
were associated with wind speeds more than 10 mph, which suggests that the highest levels at this
station were mainly due to fugitive dust. At Station 1 , high levels were associated with both low and high
wind speeds, indicating that both active emissions and fugitive dust from the Plants can result in high
44
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PM10 levels at this station. Station 4 is located on the edge of Pocatello and is not directly downwind from
the Plants under most meteorological conditions. This suggests that the modestly elevated PM10 levels
seen at this station were due at least in part to non-Plant-related sources such as dust, wood smoke, and
vehicular emissions.
Maximum daily average PM10 levels were elevated only at stations 2, 5, and 7. As discussed above, the
highest levels at Station 2 are probably due to fugitive dust from the Plants. Stations 5 and 7 appear to
receive the greatest amounts of contamination from the Plants when the winds are light, indicating that
the elevated maximum levels seen at these stations probably reflect active emissions from the Plants.
The concentrations measured at all of the stations are indicative of the exposure's residents living near
those stations could experience. Currently, there are no residents living near stations 1 or 2, which had
the highest annual average levels. Residents do live in the vicinity of stations 3,4, and 5; however, PM10
levels either are not consistently elevated (stations 3 and 5) or do not appear to reflect site-related
contamination (Station 4) at these locations.
The airborne contaminant concentrations measured at Station 2 have been assumed to be of
representative exposure point concentrations for Plant workers since airborne contaminant
concentrations were not measured within the operating areas of the Plants. Based on this assumption,
it appears that Plant workers could be exposed to PM10 concentrations above the NAAQSs.
The PM10 levels measured at Station 2 could cause respiratory irritation and could aggravate the
symptoms of patients with a previous history of asthma, bronchitis, emphysema, or other respiratory
diseases.
6.2 Ecological Risk Assessment
A baseline ecological risk assessment was conducted for the EMF site to evaluate the potential for
effects of site-related contamination on the natural environment in accordance with EPA regulatory
guidance. The findings of the ecological risk assessment are presented below.
Important ecosystems occurring in the vicinity of the site include the riverine, open-water, and mudflat
habitats of the Portneuf River and American Falls Reservoir. Extensive areas of native upland sagebrush
steppe ecosystems also occur in the foothills and river plains adjacent to the site.
The potential site-related exposure of terrestrial plants and wildlife to COPCs4 (See Table 32 for a list of
Ecological COPCs) was quantitatively estimated. Exposure of aquatic and semi-aquatic birds and
mammals to cadmium in river delta sediment was also quantitatively estimated. The following receptors
of concern at the site were selected for evaluation:
Sagebrush Steppe Habitat: shrubs (big sagebrush), grasses (thickspike
wheatgrass), mammalian carnivores (coyote), small mammals (deer mouse),
'Other contaminants may be added to this list if new analytical methods become available (such
as for P4) or new information indicates other contaminants pose a potential risk.
45
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Page I of 1
Table 32
SUMMARY OF ECOLOGICAL COPCs BY MEDIA
Chemical
Arsenic
Beryllium
Cadmium
Chromium
Copper
Fluoride
Lead-210
Mercury
Molybdenum
Selenium
Silver
Thallium
Vanadium
Zinc
Total number of COPCs
Soil
"X
X
„»-:>.', *
X
xe
X
/ X
7
Sediment
Portneuf River
Xb
xc
xb
X
X
xb
xe
xb
xb.c
X
xc
X
xb
13
Portneuf River
Delta"
- x
1
Surface Water
xd
X
X
X
4
, See Section 3.
D
COPC selected for investigation in Portneuf River delta.
, Chemical exceeds background; ecological screening criteria not available.
Mercury is considered a COPC in surface water due to the insensitivity of the analytical method (see Section
2.3.2.2) and the concern with mercury contamination of the aquatic food chain, raised from previous studies in
American Falls Reservoir (sec Appendix F).
Key:
COPC = Contaminant of Potential Concern.
= COPC selected for quantitative risk analysis.
-------
large herbivorous mammals (mule deer), upland game birds (sage grouse), raptors (red-tailed hawks),
and songbirds (horned larks).
• Riparian Habitat: shrubs (Russian olive) and songbirds (cedar waxwing).
River Delta Habitat: waterfowl (mallard), shorebirds (spotted sandpipers), and
semi-aquatic herbivorous mammals (muskrat).
Cumulative exposure estimates were derived based on site-specific contaminant data and exposure
parameters published in literature, such as dietary composition, home range, exposure duration,
ingestion rate, and body weight. Both dietary exposure routes and incidental ingestion of contaminated
media were quantitatively assessed. Estimated exposures to COPCs were greater for receptors at the
site areas compared to exposure for receptors at background locations. The importance of soil ingestion
versus food as a percentage of total exposure varied with location, receptor, and COPCs.
The potential toxic effects of COPCs were evaluated based on toxicity benchmarks derived from
literature. Conservative assumptions were used where necessary to account for uncertainties of
extrapolation from literature studies. Toxicity reference values derived in this manner are likely to
encompass the broad range of wildlife sensitivity to COPCs.
For each receptor, the potential ecological risks of each COPC were estimated by calculating a hazard
quotient (HQ), which is defined as the total estimated exposure received through all relevant pathways
divided by the appropriate toxicity reference value. An HQ greater than 1 indicates a potential risk of
adverse chronic effects resulting from exposure. HQ's for plants, mammals, and birds are summarized
in Tables 33-35.
Potential risks of adverse effects of fluoride on resident plant and wildlife species of the sagebrush steppe
ecosystem were identified. Potential site-related risks were not identified for cadmium or zinc in any of
the habitats affected by the site. The estimated risks of fluoride are only marginally above the threshold
for toxic effects, and by inference the species at risk may be marginally but not severely affected.
Because the potential risks were quantified for effects on individual organisms using conservative
assumptions to account for uncertainty, and because the upland species most likely to be impacted occur
commonly throughout the region, widespread or significant ecological effects at the population and
community levels are not expected. ,
Given the ongoing air emissions and cumulative toxicity of fluoride, the potential for impacts is expected
to increase over time with continued air deposition. A reduction in fluoride loadings could allow for a
reduction in the potential for harmful effects "on the ecosystem in the future, as well as a reduction in
current risks.
6.3 Uncertainty
The numerical results of a risk assessment have inherent uncertainty because of limited knowledge
regarding exposure and toxicity, and because of limitations due to the accuracy and representativeness
of environmental sampling. Whenever available and appropriate, site specific information from the Rl
was used for estimation of exposure to reduce uncertainty. Where information was incomplete.
47
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conservative assumptions were made and/or conservative default values were used to ensure protection
of public health and the environment.
The following sections summarize the most significant uncertainties associated with scenarios in the EMF
Human Health and Ecological Risk Assessments.
6.3.1 Uncertainty in the Human Health Risk Assessment
The greatest uncertainties affecting the estimates of potential residential exposures appear to be in the
estimates of the soil-to-plant and plant-to-animal transfer factors and in the bioavailability of contaminants
in soils that might be accidentally ingested. The soil-to-plant transfer factor for cadmium, which accounts
for the bulk of the estimated noncancer risk from consumption of homegrown produce, was based on
actual data for the local area, and therefore appears to be fairly reliable.
The greatest uncertainties affecting the estimates of potential worker exposures appear to be the
estimates of specific radionuclide concentrations in ground water and soil that had to be estimated from
gross alpha measurements, the estimates of radon infiltration into ouildings that might be constructed
on site in the future, and estimates of the external radiation exposure to current workers derived from the
aerial radiological survey of the area conducted in 1986. Confidence in the estimated radiological risks
associated with potential ground water consumption is low because of the first factor cited. While there
is considerable uncertainty in the modeling process used to estimate potential radon concentrations in
future site buildings, the values obtained appear to be consistent with concentrations actually measured
in existing site buildings in the past; therefore, these risk estimates appear to be at least moderately
reliable. There are some uncertainties in estimating current external radiation exposures from measure-
ments made in 1986. The 1986 data, however, were actual exposure rates measured for the site;
therefore, the risk estimates based on these measurements also are believed to be at least moderately
reliable.
Uncertainty in the quantitative toxicity estimates for the COPCs for the site also affects the reliability of
the risk estimates. However, the confidence in the reference doses and slope factors for the COPCs
driving the estimated risks for the site is considered to be moderate to good.
6.3.1.1 Air Pathway Uncertainty
The following are several factors that contribute ta the uncertainty associated with the risk estimates for
the air pathway: (1) The meteorology during the Superfund air monitoring may not have adequately
represented the range of possible valley weather patterns. (2) Only three of four furnaces were in
operation during the CERCLA monitoring period (the associated feedstock operations and calcining were
also at reduced capacity). (3) Air monitors were sited for chemical speciation and to verify the
representativeness of the model. There were not necessarily sited to represent the Reasonable
Maximum Exposed Individual. (4) Since the Remedial Investigation air monitoring effort was completed,
FMC's ore has been mined from a different source. Current feedstocks may be richer in some COPCs.
(5) Certain constituents were not included in the study, (i.e., Phosphine and Hydrogen Cyanide). (6)
Wedding filters were used for collection of PM10 data. These filters may on average provide readings
20% less than comparable Sierra Anderson Units. Another source of uncertainty with the air pathway
risk estimates are in relation to phosphorus and its oxidation products. Quantitative evaluation of
potential risks from phosphorus and its oxidation products were unavailable due the lack of a standard
48
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EPA method for measurement of these constituents in air, and lack of information of the lexicological
effects from inhaling low levels of these substances over a prolonged period of time. Because of the
importance of assessing the risks from releases of phosphorus and its oxidation products to the air at the
EMF site, EPA investigated the use of non-EPA methods for measuring these substances in air. Several
methods were considered, but none were sufficiently specific and well validated to generate quality data
that would meet EPA's guidelines for data useability in risk assessments. Therefore, EPA reluctantly
concluded that it was not possible to collect useable data on the concentrations of phosphorus and/or
its oxidation products as part of the Rl for the site.
In addition, more recently EPA's air program and the Shoshone Bannock Tribes established three new
air quality monitoring sites adjacent to the industrial complex northwest of Pocatello in October 1996.
From October 7 through December 31, 1996, these sites recorded twenty-two days when levels of
particulate matter near the industrial complex were measured above the national participate standard of
150 micrograms per cubic meter. These levels are nearly 50% higher than that measured during a
comparable period of time during the Superfund air monitoring program. It is uncertain what has
contributed to these observed differences and it is unclear if the specific contaminants of concern
evaluated in the risk assessment would also be expected to increase by 50%.
6.3.1.2 Summary of the Exposure Assessment Uncertainties:
Overall, the exposure estimates obtained are probably highly to moderately reliable for COPCs at the
EMF site. Several of the factors adding uncertainty to the estimates tend to result in overestimation of
exposure. These include:
• The directed nature of the sampling program;
The use of conservatively estimated or extrapolated values for some exposure
point concentrations; and,
The use of conservative exposure parameter values in the exposure estimation
calculations.
One factor that could lead to an underestimation of the exposures is:
The use of sample quantitation limits that could result in missing low
concentrations of some contaminants that might pose significant risks.
Finally, one factor that could lead to overestimation or underestimation of exposures is:
• The use of the steady state assumption for source concentration estimates.
The cumulative effect of all of the exposure uncertainties most likely is to overestimate the true potential
exposure.
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6.3.1.3 Summary of Toxicity Assessment Uncertainties
The basic uncertainties underlying the assessment of the toxicity of a chemical include:
• Uncertainties arising from the design, execution, or relevance of the scientific
studies that form the basis of the assessment;
• Uncertainties involved in extrapolating from the underlying scientific studies to the
exposure situation being evaluated, including variable responses to chemical
exposures within human and animal populations, between species, and between
routes of exposure; and
• The absence of quantitative lexicological indices for some chemicals that may
result in underestimation of the total risks posed by the site.
These basic uncertainties could result in a toxicity estimate, based directly on the underlying studies, that
either under-or overestimates the true toxicity of a chemical.
6.3.2 Ecological Risk Assessment Uncertainties
Confidence in the results of the risk assessment is considered to be high. Maximal use was made of
site-specific exposure data, thereby reducing a major source of uncertainty. Exposure estimates for
plants and wildlife was based on statistically designed sampling; hence, the modeled exposure estimates
have a high degree of reliability. Toxicity testing and chemical analysis of sediments provides adequate
information to evaluate potential impacts of contaminants to the Portneuf River, which were judged to be
minimal. In general, the risk assessment is more likely to overestimate rather than underestimate the
risks of adverse effects of the site because of the conservative nature of the assumptions used.
Principal uncertainties and limitations of the risk assessment are related to selection of a limited number
of COPCs and endpoint species for evaluation, deficiencies of the fluoride chemical analyses,
assumptions used to derive exposure estimates and toxicity reference values, the limited field verification
of risks, and interpretation of the broader ecological significance of the hazard quotients.
6.4 Need for Action
i
The Baseline Risk Assessment (Human and Ecological) supports the conclusion that hazardous
substances are found on the site and that the actual or threatened release of these substances from this
site, if a response action is not taken, may present an imminent and substantial endangerment to public
health, welfare, or the environment.
7.0 Remedial Action Objectives
The overall objective of the remedial actions for the Eastern Michaud Flats site is to provide an effective
mechanism for protecting human health and the environment from contaminated site soils and ground
water. To address the potential risks from the site, the following cleanup objectives were developed:
50
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.1 PMC and Simplot Plant
Reduce the exposure to radon that would occur in future buildings constructed within the
Plant Areas under a future industrial scenario.
Prevent external exposure to radionuclides in soils at levels that pose estimated excess
cancer risks greater than 1x10"', or site specific background levels where that is not
practicable.
Prevent ingestion or inhalation of soils containing Contaminants of Concern (COCs) at
levels that pose estimated excess risks above 1 x 10"4, a non cancer risk HQ of 1, or site-
specific background levels where that is not practicable.
Reduce the release and migration of COCs to the ground water from facility sources that
may result in concentrations in ground water exceeding risk-based concentration (RBCs)
or chemical specific Applicable or Relevant and Appropriate Requirement (ARAR),
specifically Maximum Contaminant Levels (MCLs).
Prevent potential ingestion of ground water containing COCs having concentrations
exceeding RBCs or MCLs (chemical specific ARARs) (see Table 36). The RBCs shown
in Table 36 correspond to a cancer risk of 104 or a Hazard Index of 1.0.
Restore ground water that has been impacted by site sources to meet all RBCs or MCLs
for the COCs
7.2 Off-Plant Area
The following cleanup objectives would apply for the Off-Plant Area:
Prevent future consumption of homegrown produce grown in areas of the site where soil
constituents levels result in a potential noncarcinogenic risk exceeding a HQ of 1.
Prevent external exposure to radium-226 in soils at levels that pose cumulative estimated
excess risks above 1x10"*.
Prevent the potential for future impacts to ecological receptors by monitoring fluoride at
the site and surface water at springs (see Table 37 of ecological COCs and Risk-based
Concentrations). If monitoring data indicates that fluoride levels in the environment are
increasing, beyond that observed during the Rl sampling, and the potential for an
unacceptable ecological risk is indicated, additional actions, including source controls,
may be required.
51
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TABLE 36
RISK BASED AND MAXIMUM CONCENTRATION OF CONTAMINANTS OF
CONCERN IN GROUNDWATER
Substance of
Concern
'**•#&&&
'•&&>•?'%$$
Beryllium
Boron
Cadmium
Chromium
Mercury
Nickel
1 M
VjfZK MHff^QRMffimBw
f^s^^^f^m^i^^m
K^KKS' ^S^a^MC"§^^S^is^S^SS^^^:
Wm ?jf&E\ * jv^mm^aS^^^^^^^a
m ^ft^vf^^^^^m^SK
"* x ' « •> Tr^flKfSHrwTi?
Vanadium
Zinc
Tetrachloroethene
Trichloroethene
':dc^^p^|$|^|
Units
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
pCi/L
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
pCi/L
pCi/L
Maximum Detected
Concentration
1.07
5.53
.083
89
3.9
7.58
2,815
91.2
.0043
3.46
660
7.09
19.73
9.09
22.317
28.9
i
.035
.028 -
1,690
l,355pCi/l
Risk Based
Concentration
.006
.000048
.000019
1.36.
.008
.077
.93
.077
.0046
.299
25.03
.39
.07
.001
.108
3.92
.001
.002
__
Maximum
Contaminant
Level (MCL)
.006
.05
.004
_
.005
0.1
4
_
.002
0.1
10
5*
.05
.002
_
__
.005
.005
15
4 mrem/yr
Key:
* Combined Ra 226 and Ra 228
1 RBCs for groundwater based on drinking water and watering homegrown produce. RBC value
based on cancer risk of 10"* or HQ=1
b Individual radionuclides potentially responsible for elevated gross alpha and gross beta levels
are also COPCs. These include, but are not limited to, Lead-210, Polonium-210, Potassium-40,
Thorium-230, Uranium-234, and Uranium-238.
c Beta particle and photon activity based on consumption of 2 liters/day
Shaded chemicals are COCs identified in the FS
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Prevent potential ingestion of ground water containing COCs having concentrations
exceeding RBCs or MCLs (chemical specific ARARs) (see Table 36). The RBCs shown
in Table 36 correspond to a cancer risk of 10*6 or a Hazard Index of 1.0.
With respect to radionuclides and metals in soils, the above remediation goals were established after first
considering the 10'6 excess risk as the point of departure. However, since local background for these
radionuclides poses risks greater than 10"6, the 10* level is the most protective risk level which is
measurable and above background.
8.0 DESCRIPTION OF ALTERNATIVES
Each of the remediation alternatives in this section was developed as a way to mitigate the risks from
contamination on the site. A general discussion of each of the alternatives follows.
The FS evaluated a range of alternatives for each subarea that could be used to address actual and/or
potential threats posed by the site. These alternatives are summarized below and include capital and
Operation and Maintenance (O&M) costs discounted at a 5 percent rate of return over 30 years. Since
the FS alternatives used similar numbering for each subarea, the following letters have been added to
the alternatives: 0- represents an Off-Plant area alternative, F- represents an FMC plant alternative, and
S- represents a Simplot plant alternative.
These alternatives were initially compared on the basis of effectiveness, imptementabilrty and cost. The
alternatives presented below were evaluated in detail. Alternatives F1 and S1 (no action) for the FMC
and Simplot plants were eliminated because they were identical to alternatives F2 and S2 (no further
action), but did not recognize actions already taken by the Companies. EPA considers alternatives O1,
F2, and S2 as the baseline by which other alternatives should be compared.
All alternatives include some provision for review of the cleanup at least every 5 years to ensure the
remedy remains protective. The primary difference among the alternatives at FMC is the type of capping
proposed for the old phossy pond and calciner solids areas. The primary difference for Simplot
alternatives is the action to be taken on the gypsum stack. These alternatives are as follows:
8.1 Off-Plant area
8.1.1 Alternative 01: No Action
Capital Cost: SO
Annual O&M Cost: $0
Present Worth 30-Year Cost Estimate: $0
No action would be taken under this alternative. It was included because it is required by EPA's
guidance, and establishes a baseline to compare the level of environmental protection provided by other
alternatives.
8.1.2 Alternative 02: Vegetation/Bio Monitoring
Capital Cost: SO
Annual O&M Cost: $12,200
30-Year Cost Estimate: $187,544
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Alternative 2 consists of a program to monitor levels of fluoride in the Off-Plant area. This would consist
of periodic collection and analysis of vegetation or some other form of biomonitoring to assess the levels
of fluoride in the environment. This alternative has been developed to address the potential risk for
ecological receptors due to ingestion of vegetation containing fluoride.
8.1.3 Alternative 03: Institutional Controls
Capital Cost: $183,094
Annual O&M Cost: $12.200
Present Worth 30-Year Cost Estimate: $370,637
This alternative includes the monitoring elements of alternative 02, and land use controls5 such as
recorded deed restrictions, and environmental easements to restrict property use and inform future
property owners of the potential human health risks associated with consumption of homegrown produce
from this area. Implementation of this alternative would likely include a combination of these controls with
a preference for environmental easements.
8.1.4 Alternative 04: Removal and Replacement of Soil Cover
Capital Cost: $6,869,304
Annual O&M Cost: $12.200
Present Worth 30-Year Cost Estimate: $7,056,848
Alternative 04 includes all actions under alternative 03, and removal/replacement and/or covering of soils
at the time of any future residential development if the soils exceed cadmium or radium-226 levels that
represent an unacceptable excess risk.
8.2 FMC Subarea (FMC)
8.2.1 Alternative F2: No Further Action
Capital Cost: $0
Annual O&M Cost: $0
Present Worth 30-Year Cost Estimate: $0
No further action would be taken under this alternative. It was included because it is required by EPA's
guidance, and establishes a baseline to compare the level of environmental protection provided by other
alternatives. This alternative does recognize a number of actions taken during the course of the Rl by
FMC to meet various environmental regulations (see section 2.4.2). Some of the major actions include:
Installation of air scrubbers (1991); closure of the unlined pond 8S (1994); construction of new RCRA
surface impoundment- 16S (1993); paving of plant roads (1993); construction of a new lined calciner
pond (1993); and, placement of some deed restrictions on FMC property to prohibit residential use in the
future. FMC has estimated that the costs of the various projects completed over the last few years at
$31,600.000.
5 The Off-Plant areas are currently zoned as industrial by Bannock County. However
this alternative does not rely on zoning to control future land use, because it is subject to
change by local government.
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8.2.2 Alternative F3: Institutional Controls and Ground water Monitoring
Capital Cost: $63.000
Annual O&M Cost: $84,000
Present Worth 30-Year Cost Estimate: $1,354,000
Alternative F3 relies on the use of institutional controls to prevent or minimize contact, ingestion, or
inhalation of contaminants in soils and ground water. Institutional controls include the following: plant
access restrictions such as fencing and security; plant work rules such as use of personal protection
equipment; plant construction practices to reduce radon levels in buildings; land use restrictions
controlling future use; and water usage restrictions to prevent ingestion of affected ground water. This
alternative also includes a ground water monitoring program to evaluate the effectiveness and efficiency
of the remedial action selected.
8.2.3 Alternative F4: Institutional Controls, Surface Controls and Soil Cover, and Ground water
Monitoring
Capital Cost: $3,130,000
Annual O&M Cost: $109.000
Present Worth 30-Year Cost Estimate: $4,798,000
This alternative includes all actions of alternative F3 (institutional controls) plus grading, soil cover, and
vegetation for the calciner pond solids area6 and old phossy waste pond areas (Ponds 1S-7S, 1E-7E, 9S,
and 10S), and lining of the railroad swale. Grading would consist of backfilling low areas (e.g., former
Ponds 1E, 4E, and 9S) to bring them up to the surrounding grade levels, and then shaping the surfaces
to enhance surface drainage and reduce the potential for infiltration. A surface soil cover of 12 inches
would be placed over the backfill. Runoff would be directed toward natural drainage collection areas in
the northern and northwestern portions of the FMC property. The total area to be graded and covered
is approximately 44 acres. Actions in the railroad swale area would involve extension of the existing liner
to prevent infiltration of surface water runoff.
8.2.4 Alternative F4A: Institutional Controls, Surface Controls and Capillary Barrier Cap, and
Ground water Monitoring
Capital Cost: $6,620,000
Annual O&M Cost: $109,000
Present Worth 30-Year Cost Estimate: $8,288,000
This alternative includes all actions of alternative F4 but replaces the 12 inches of soil cover with a
capillary, barrier cap for the calciner pond solids area and old phossy waste pond areas (Ponds 1S-7S,
1E-7E, 9S, and 10S). The capillary barrier cap design under consideration consists of 2 feet of top soil
underlain by a 6-inch gradational layer and 18 inches of well sorted coarse material, which can be either
slag or river gravel. Runoff would be directed toward natural drainage collection areas in the northern
and northwestern portions of the FMC property, as included in alternative F4. The total area to be graded
and covered is approximately 44 acres.
5 In 1993 the old calciner ponds were replaced with double lined ponds. The calciner
solids are the material and underlying contaminated soil that was excavated from the old ponds.
It is now stored in an area south of the new ponds.
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8.2.5 Alternative F5A: Institutional Controls, Source Containment and Native Soil Cap, and
Ground water Monitoring
Capital Cost: $3,994,000
Annual O&M Cost: $109,000
Present Worth 30-Year Cost Estimate: $5,662,000
This alternative includes all actions of alternative F4 (institutional controls and grading and soil cover)
except that the cover on the calciner solids area and old phossy waste pond areas would include an
additional 12 inches of subgrade material below the soil cover (the FS refers to this as a 'native soil cap").
For the calciner pond solids area, hydro seeding with native plant species is proposed. For the old
phossy waste pond areas, vegetative cover is also proposed; however, due to the location of these areas
with respect to active plant operations, other surface materials that would withstand local traffic may be
appropriate above the native soil cap. Like alternative 4, the total area to be covered with native soil is
approximately 44 acres.
8.2.6 Alternative FSB: Institutional Controls, Source Containment and Asphaltic Concrete Cap,
and Ground water Monitoring
Capital Cost: $4,443,000
Annual O&M Cost: $153.000
Present Worth 30-Year Cost Estimate: $6,787,000
This alternative includes all actions under alternative F5A (institutional controls, grading, and native soil
cap) except that an asphaltic concrete cap would be placed over the old phossy waste ponds. Grading,
shaping, and placing soil cover on the calciner pond solids would be the same as described in Alternative
4. The asphaltic cap would consist of 10 inches of subgrade material, 9 inches of base, topped with a
minimum of two inches of asphaltic concrete.
8.2.7 Alternative F5C: Institutional Controls, Surface Controls and Multi-Layer Cap, Source
Containment, and Ground water Monitoring
Capital Cost: $11.856.000
Annual O&M Cost: $109.000
Present Worth 30-Year Cost Estimate: $13,524,000
Institutional Controls and Ground water Monitoring were described under Alternative F3 and are also
included in this alternative. This alternative includes all actions of alternative F4 (institutional controls)
plus grading, soil cover, and vegetation for the calciner pond solids area and old phossy waste pond
areas (Ponds 1S-7S, 1E-7E, 9S, and 10S) and lining of the railroad swale. Grading and placement of
the cap in the old phossy waste ponds would be the same as described in Alternative F5A, except that
instead of a native soil cap, a multi-layer cap would be used. The multi-layer cap would consist of a
minimum of six inches of subgrade overlain by a geosynthetic clay liner (GCL), and a flexible membrane
liner (40 mil minimum). A protective cover with a minimum thickness of three and one-half feet would be
constructed above the GCL and flexible membrane liner. The upper layer would consist of 12 inches of
topsoil, which would be hydro seeded with native vegetation.
8.2.8 Alternative F6A- Institutional Controls, Source Containment and Asphaltic Concrete Cap,
Excavation and Disposal, and Ground water Monitoring
Capital Cost: $10,160.000
Annual O&M Cosl: $153^000
Present Worth 30-Year Cost Estimate: $12.504,000
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Institutional Controls and Ground water Monitoring were described under Alternative F3 and are also
included in this alternative. This alternative includes all actions of alternative F3 (institutional controls)
plus grading, soil cover, and vegetation for the calciner pond solids area and old phossy waste pond
areas (Ponds 1S-7S, 1E-7E, 9S, and 10S) and lining of the railroad swale.
This alternative includes the asphaltic cap as described under alternative FSB for the old phossy waste
ponds and adds excavation and disposal of the calciner pond solids into a new, secure landfill. The
landfill would have two geomembrane bottom liners, with a leachate collection between the two liners.
A multi-layer cap similar to that described in F5C would be placed over the calciner pond solids once all
of the solids have been excavated and placed in the new landfill.
8.2.9 Alternative F6B: Institutional Controls, Surface Controls and Soil Cover, Excavation and
Stabilization, and Ground water Monitoring
Capital Cost: $14.675,000
Annual O&M Cosl: $109.000
Present Worth 30-Year Cost Estimate: $16,343,000
This alternative is identical to F6A with the exception that the calciner solids would be stabilized prior to
placement in a new landfill. Excavation and ex-situ stabilization consists of excavating and removing the
calciner pond solids from their existing disposal area, mixing these materials with Portland cement or
another stabilizing agent, and placing the stabilized material in a new landfill. The landfill would have a
cap as described in Alternative F6A.
8.2.10 Alternative F7-lnstitutional Controls, Surface Controls and Multi-Layer Cap, and Ground
water Monitoring, Extraction and Recycling:
Capital Cost: $12.381,000
Annual O&M Cost: $123.000
Present Worth 30-Year Cost Estimate: $14,264,000
Institutional Controls and Ground water Monitoring were described under Alternative F3 and are included
in this alternative. This alternative also includes the actions for the calciner solids area described under
alternative F4, and the actions for the old phossy waste pond areas described under alternative F5C.
This alternative adds a ground water extraction system. This system would consist of installing wells near
the northern boundary of the FMC property, and extracting ground water from the shallow aquifer at a
rate sufficient to capture contaminated ground water above MCLs. Ground water flow modeling indicates
extraction of a total of approximately 350 gallons per minutes at two locations would be sufficient to
intercept the ground water plume. This water is expected to be near or below MCLs when extracted.
The water may be of a quality suitable for use in the FMC plant without treatment or potentially
discharged to the Portneuf River. This discharge would be subject to the requirements of the NPDES
permit program.
8.2.11 Alternative FSB- Institutional Controls, Surface Controls and Asphaltic Concrete Cap,
Excavation and Stabilization, and Ground water Monitoring, Extraction, Treatment and Recycling
Capital Cost: $18.988,000
Annual O&M Cost: $704JDOO
Present Worth 30-Year Cost Estimate: $29,802,000
Institutional Controls and Ground water Monitoring were described under Alternative F3 and are included
under this alternative. This alternative also includes actions for the old phossy waste ponds described
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under alternative FSB, actions for the calciner pond solids area described under F6B, and ground water
extraction described under alternative F7. This alternative adds a process to treat extracted ground
water. Extracted ground water would be piped to an equalization tank, treated by chemical precipitation
(ferric chloride), and added to the Industrial Waste Water basin return water line. Solids produced from
the treatment process would be disposed of in an on-site hazardous waste management unit.
8.3 Simplot Plant
8.3.1 Alternative S2: No Further Action
Capital Cost: $0
Annual O&M Cost: $0
Present Worth 30-Year Cost Estimate: $0
No further action would be taken under this alternative. It was included because it is required by EPA's
guidance, and establishes a baseline to compare the level of environmental protection provided by other
alternatives. This alternative does recognize a number of actions taken during the course of the Rl by
Simplot to meet various environmental regulations (see section 2.4.1). Some of the major actions taken
or planned include removal of the unlined East Overflow Pond and replacement with a lined
impoundment, repair of a leaking underground line from the Nitrogen Solutions Plant and replacement
with a double lined pipe, installation of several lined treatment ponds, installation of an ore slurry pipeline,
decommissioning of the calciners, road paving, and installation of additional air emission control systems.
Simplot has estimated that the costs of the various environmental projects completed during the last few
years at approximately 56 million dollars.
8.3.2 Alternative S3: Institutional Controls & Ground water Monitoring
Capital Cost: $96.434
Annual O&M Cost: $62,464
Present Worth 30-Year Cost Estimate: $1,056,659
This alternative combines a variety of institutional controls for ongoing Don Plant operations including the
following; additional worker safety programs and personnel monitoring primarily to reduce risks from
gamma radiation; requirements for radon-resistant buildings constructed in the plant area in the future;
and, ground water quality monitoring and legally enforceable restrictions to prevent use of impacted
ground water.
8.3.3 Alternative S4A: Institutional Controls, Removal/Disposal, Source Control #1
Capital Cost: $855,585
Annual O&M Cost: $145/119
Present Worth 30-Year Cost Estimate: $3,086,420
This alternative includes the institutional controls and ground water monitoring of alternative S3 and adds
the following components: (1) Excavation of Phosphate Ore Residue from the dewatering pit, disposal
of excavated material on the Gypsum Stack and covering the excavated area with soil and vegetation;
(2) Excavation of gypsum sediments from the former east overflow pond, disposal on the gypsum stack,
and installation of a new 60 mil, high density polyethylene synthetic lined pond. The new pond would be
used for the temporary storage of liquids during plant upsets or power failures; (3) Improvements in the
Gypsum Stack Decant System to reduce the amount of ponded water on the surface of the upper
gypsum stack: and, (4) Construction of a stable road surface on the gypsum stack to reduce fugitive
emissions.
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8.3.4 Alternative S4B: Institutional Controls, Removal/Disposal, Ground water Containment,
Source Control #1
Capital Cost: $1,544,406
Annual O&M Cost: $175.619
Present Worth 30-Year Cost Estimate: $4,224,405
This alternative includes all the components of alternative 4a (institutional controls, ground water
monitoring, and source control) plus the installation of a network of ground water extraction system wells
immediately downgradient of the gypsum stack. The purpose of this extraction system is to intercept
ground water Contaminants from the gypsum stack and prevent them from spreading further into the
aquifer. The extracted ground water may be of sufficient quality to be used in the Simplot process without
treatment.
8.3.5 Alternative S5: Institutional Controls, Removal/Disposal, Source Control #2
Capital Cost: $56.344,875
Annual O&M Cost: $7,959,463
Present Worth 30-Year Cost {Estimate: $175,402,962
This alternative is the same as Alternative S4B, except that instead of installing an improved decant
system on the gypsum stack and a ground water extraction system, an impervious geosynthetic liner
would be installed on the top of the gypsum stack and the decanted liquid returned to the process via a
leachate collection system. Under this option gypsum placement would continue on top of the new liner.
This alternative would also include asphalt paving of roads on the gypstack due to increased traffic during
installation of the synthetic liner.
9.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
The NCP requires that each remedial alternative analyzed in detail in the FS be evaluated according to
specific criteria. The purpose of this evaluation is to promote consistent identification of the relative
advantages and disadvantages of each alternative, thereby guiding selection of remedies offering the
most effective and efficient means of achieving site cleanup goals. There are nine criteria by which
feasible remedial alternatives are evaluated. While all nine criteria are important, they are weighed
differently in the decision-making process'depending on whether they describe a consideration of
technical or socioeconomic merits (primary balancing criteria), or involve the evaluation of non-EPA
reviewers that may influence an EPA decision (modifying criteria).
9.1 Threshold Criteria
The remedial alternatives were first evaluated by comparison with the threshold criteria: overall protection
of human health and the environment and compliance with ARARs. The threshold criteria must be fully
satisfied by candidate alternatives before the alternatives can be given further consideration in the
remedy selection process.
9.1.1 Overall protection of human health and the environment Determines whether an alternative
eliminates, reduces, or controls threats to public health and the environment through institutional controls,
engineering controls, or treatment.
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Off-Plant area- Alternative 01 (no action) and Alternative 02 (monitoring only) do not control exposures
from potential consumption of homegrown fruits and vegetables to satisfy this criterion. Alternatives 03
(institutional controls and monitoring) and 04 (institutional controls, monitoring, and soil removal) both
meet this criterion by preventing or controlling potential future exposures to soils in the Off-Plant area.
Note: Since alternatives 01 and 02 do not meet this threshold criteria they are not discussed further in
this ROD.
Simplot- Alternative S2, (no further action) would not meet this criterion because it does not prevent
exposure to indoor radon or contaminated ground water above MCLs in the future. Alternatives S3
(institutional controls) or S4A (institutional controls, removal/disposal, gypsum decant system) would
provide protection of human health for future workers by land use restrictions but would not eliminate or
reduce contamination to ground water at the gypsum stack. Alternatives S4B (institutional controls,
removal/disposal, ground water extraction) and alternative S5 (gypsum stack liner) meet this criterion by
capturing leachate either at the base of the gypsum stack or on the liner, thereby reducing or eliminating
contamination to ground water. This should result in significant improvement in ground water quality in
the Plant area. Note: Since alternatives S2. S3. and S4a do not meet this threshold criteria they are not
discussed further in this ROD.
FMC- Alternative F2 (no further action), and alternative F3 (institutional controls & ground water
monitoring) do not provide sufficient protection for future workers from potential ingestion of contaminants
in ground water or from radon emissions from soils and solids. Alternatives F4 through FSB meet this
criterion by relying on institutional controls for protection of future workers from exposure to contaminants
in ground water and on a combination of engineering controls and institutional controls for protection from
contaminants in soils and solids. All of these alternatives except FSB ultimately rely - fully or partially -
on natural processes to reduce contaminants in ground water to MCLs or background levels. Alternatives
F7, F8A, and FSB would accelerate the process to some degree. Note: Since alternatives F2 and F3 do
not meet this threshold criteria they are not discussed further in this ROD.
9.1.2. Compliance with Applicable or Relevant and Appropriate Requirements (ARARs) evaluates
whether the alternative meets State and Federal environmental and facility siting laws and regulations
that pertain to the site or, if not, if a waiver is justified.
Off-Plant area- No specific ARARs have been identified for the Off-Plant area soils. Ground water in this
area currently meets drinking water standards and it is expected to continue to meet MCLs.
Simplot- Both alternative S4B and S5 meet the requirements of all identified ARARs for current Simplot
operations and for a future alternate industrial scenario.
FMC- As discussed in section 4 of this ROD a number of ponds and units at FMC are subject to
regulation under RCRA. EPA has determined that the RCRA closure requirements are neither applicable
nor relevant and appropriate for CERCLA actions in the areas which are the subject of this ROD. The
FS alternatives for these areas were designed to reduce infiltration, prevent incidental ingestion, reduce
exposure to radiation, and minimize maintenance. Alternatives F4 (grading and soil cover), F4A (capillary
barrier cap), F5A (native soil cap), FSB (asphaltic cap), and F5C (multi-layer cap) will minimize infiltration
(to at least a 1 x 10'7 cm/sec permeability), minimize maintenance, and control, minimize or eliminate
releases to the extent necessary to protect human health and the environment. These alternatives plus
F6A, F6B, F7, and FSB meet the requirements of all identified ARARS for current FMC operations and
for a future alternate industrial scenario.
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9.2 Primary Balancing Criteria
For those alternatives satisfying the threshold criteria, five primary balancing criteria are used to evaluate
other aspects of the potential remedies. No single alternative will necessarily receive the highest
evaluation for every balancing criterion. This phase of the comparative analysis is useful in refining the
relative merits of candidate alternatives for site clean up. The five primary balancing criteria are: long-
term effectiveness and permanence; reduction of toxicity. mobility, or volume through treatment; short-
term effectiveness; implementability; and cost.
9.2.1. Long-term effectiveness and permanence This criterion addressed the results of each
alternative with respect to the risk remaining at the site after the conclusion of the remedial action.
Evaluation of this criterion includes an assessment of the magnitude of the residual risk from untreated
waste or treatment residuals. It also includes an assessment of the adequacy, reliability, and useful life
of any controls that are to be used to manage hazardous substances that remain on site after the
remediation.
Off-Plant area- Alternatives 03 and 04 would both satisfy this criterion although alternative 04 may be a
more permanent and reliable option which eventually could allow for unrestricted use of surrounding
properties once removal/replacement had occurred.
Simplot- Both alternative S4B and S5 would provide long term effectiveness in improving ground water
quality during continued Don Plant operation. Alternative S4B may be more reliable than alternative S5
since lining of the gypsum stack involves considerable long-term management. In addition, alternative
S5 could become less effective over time if the liner were breached or the drain system became dogged.
FMC- All remaining alternatives satisfy this criterion with regard to reliability. The multi-layer cap (F5C)
and a capillary barrier cap (F4A) provide a higher level of permanence than the 12-inch soil cover in
alternative F4. The Stabilization of calciner solids (F6B) would provide a slightly higher level of long term
risk reduction for this material than the other alternatives.
9.2.2. Reduction of toxicity. mobility, or volume through treatment or recycling Evaluation of this
criterion included: an assessment of the treatment processes to be employed by each remedial action
and the types of wastes they would treat; the amount of waste that would be destroyed or treated; the
projected amount of reduction in toxicity, mobility, or volume; the degree to which the treatment is
irreversible; and the types and quantities of residuals that would remain after treatment. Also considered
in this assessment is whether the alternative .would satisfy the expressed preference of Section 121 of
CERCLA for remedial actions that reduce toxicity. mobility, or volume of hazardous waste.
Off-site- Neither alternative 03 nor 04 contain any form of treatment.
Simplot- None of the alternatives contain any form of treatment or volume reduction, although both
alternatives S4B and S5 include paving on the gypsum stack roads which would physically restrict the
mobility of dust and soil contaminants and recycling of contaminated water within the plant.
FMC- All capping alternatives reduce the mobility of contaminants to ground water but do not use any
form of treatment. The ground water extraction and recycling in alternative F7, if it were effective, may
reduce the residual contamination remaining in the ground water. The addition of ground water treatment
as in alternative F8B, if it were effective, would reduce the mobility and reduce the volume of
contaminants.
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9.2.3 Short-term effectiveness The potential health effects and environmental impacts of each
alternative action during construction and implementation were evaluated by this criterion. The factors
assessed in this evaluation include the protection of the community and site workers during
implementation and construction, environmental impacts during implementation, and the estimated time
required to meet cleanup standards.
Off-Plant area- Only Alternative 04 involves any soil removal to achieve the cleanup goal. There could
be some short term risks to workers and the environment during implementation of the alternative.
Alternative 03 does not involve excavation of soils and does not pose any short-term risks to workers or
the environment.
Simplot- Alternative S4B provides the highest short-term effectiveness in terms of rapidity of ground water
restoration. This alternative also poses lesser risks to workers and the environment during construction
as compared to alternative S5.
FMC- Because all activities will occur at the plant, grading, hauling, and placement of the various cap or
cover materials would have little impact on the community or the surrounding environment. Most of the
source containment alternatives would not be effective in achieving ground water restoration in the short-
term. Alternatives F7, F8, FB may be slightly more effective through ground water extraction. Alternatives
F6A and F6B would pose a slightly greater risk to workers for this criterion during excavation/disposal
of calciner solids. However, these risks can be easily controlled with personal protective equipment. All
alternatives are relatively equal in regard to the time required to complete the action and achieve risk
reduction for soils.
9.2.4 Implementabilitv This criterion evaluated the terms of technical and administrative feasibility and
the availability of services and materials to accomplish the remediation. Technical feasibility includes
relative ease of installation or constructability; the ease of additional remediation, if necessary; and the
ease of monitoring the effectiveness of the remediation. Administrative feasibility addresses the degree
of procedural difficulty anticipated for each alternative in permitting and institutional requirements.
Off-Plant area- Alternative 03 includes administrative actions to secure the necessary institutional
controls in the Off-Plant area. Alternative 04 would include similar controls but would also involve closer
scrutiny to trigger the evaluation of soil conditions and cleanup at the time of land use changes in the
future. Alternative 04 would be more difficult to implement than alternative 03.
Simplot- Differences between the alternatives in terms of implementability are primarily related to
technical feasibility. Alternative S5 would be more difficult to implement due to potential problems with
stack stability, potential for liner breaches, longer implementation time, and necessary process
modifications. Both alternatives S4B and S5 are equivalent in administrative feasibility and availability
of services and materials.
FMC- There are no technical or administrative barriers that would affect the implementation of source
containment (capping phossy ponds or excavation and capping of the calciner pond solids) and all
alternatives are fairly equal. Alternative FSB would require some initial test of the solidification process
prior to full-scale operations. However, these activities can be readily implemented with no anticipated
difficulties regarding feasibility or reliability.
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9.2.5 Estimated Cost
Consistent with EPA guidance, the cost analysis for each alternative consisted of an order-of-magnitude
estimation (accurate to a range from +50% to -30%) of capital. O&M and present worth costs determined
for 30 years at a 5 percent discount rate. Table 9-1 summarizes the estimated costs and time required
to implement for the range of alternatives. The estimates are based on quotations from vendors and
contractors, conventional cost estimating guides, generic unit prices, and prior experience in the area.
They are intended as a guide in evaluating the alternatives based on information available at the time of
the estimate. Actual costs would depend on true labor and material costs, final scope, schedule, and
actual site conditions.
Off-Plant area- Alternative 03 ($370,637) is significantly less costly than Alternative 04 ($7,056,848).
Simplot- The present worth costs for alternative S5 ($175,402,962) are much higher than that for
alternative S4B ($4,224,405).
FMC- Alternative F4 is the least costly alternative that meets the threshold criteria for the phossy waste
ponds and calciner solids area with a present worth cost of $4,798,000. The most costly alternative is
alternative F8B which includes treatment of ground water with a present worth cost of $27,723,000.
9.3 Modifying Criteria
The two modifying criteria are state acceptance and community acceptance.
9.3.1 State acceptance The State of Idaho, Department of Environmental Quality, and Shoshone
Bannock Tribes have been involved with the review of the Remedial Investigation. Feasibility Study, Risk
Assessment and Proposed Plan for the site. A concurrence letter from the State is included in Appendix
C.
9.3.2. Community acceptance. The greatest number of comments received on the proposed plan
related to concerns about air quality in the vicinity of the plants and the need for ground water extraction
at FMC. EPA carefully considered these comments and made a change in the approach to ground water
extraction at FMC. With respect to air quality Superfund is not the appropriate authority to address the
ongoing air emissions from an operating facility,, and therefore no action specific to control of air
emissions is included in this ROD. The EPA responses to the comments are included in the
Responsiveness Summary in Appendix A. The local community has been kept informed throughout the
process by fact sheets and meetings.
10.0 THE SELECTED REMEDY
EPA's selected remedy combines elements from several alternatives described above. The selected
remedy meets the requirements of the two mandatory threshold criteria, protection of public health and
the environment, and compliance with ARARs. EPA believes the following actions provide overall
protection of human health and the environment while providing the best balance of benefits and
tradeoffs for the Eastern Michaud Flats site. The selected remedy uses a combination of containment
and institutional controls to achieve optimum compliance with the five balancing criteria: long-term
effectiveness, short-term effectiveness, implementability, reduction in toxicity, mobility and volume
through treatment and cost.
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The preferred remedy presented in the proposed plan outlined separate actions for the PMC plant,
Simplot plant, and Off-Plant areas. The selected remedy combines actions for these areas into two
operable units: the FMC Plant and Simplot Plant. The actions proposed for the Off-Plant areas are
included in each of the two operable units. This is the result of an underlying agreement between the two
Companies in order to allow for the creation of two operable units and ultimately two consent decrees.
The selected remedy consists of the following actions for each operable unit:
10.1 Simplot Operable Unit (OU)
10.1.1 Ground water
10.1.1.1 Ground water Extraction (Alternative S4B)
Remediation of ground water in the Simplot OU will consist of installation of a network of shallow ground
water wells on the northern edge of the gypsum stack and/or downgradient of the Nitrogen Solutions
Plant, and the installation of extraction pumps and conveyance piping. The extracted ground water will
be recycled into the Don Plant Process. The purpose of the extraction well network is: (1) to contain the
migration of COCs from the phosphogypsum stack and reduce the area! extent of shallow ground water
contamination within the Plant Area in excess of MCLs or RBCs, and (2) prevent the migration of COCs
above MCLs or RBCs into the off-plant area.
Insufficient information was generated by the Rl to sufficiently characterize this area for the purposes of
designing a ground water extraction system, or estimating recovery time once the gypsum stack is
dosed. However, a focused hydraulic test was begun in February 1997, pursuant to an EPA approved
Workplan, to support development of the ground water extraction alternative. Information from this work
will be used to help design the ground water extraction and reuse system including: (1) placement of
additional wells to provide the required ground water capture; (2) adjustment of pumping rates as needed;
and (3) modifications in the Don Plant process for reuse of the extracted ground water.
Operation and maintenance of the extraction system shall continue until COCs in ground water
throughout the Operable Unit are reduced to below MCLs or Risk-based concentrations (cancer risk
levels of 10"9 and noncancer risk Hl<1 for residential use), or until EPA determines that continued ground
water extraction would not be expected to result in additional cost-effective reduction in contaminant
concentrations within the Simplot OU.
*
10.1.1.1.2 Ground water Extraction System Evaluation
Once the ground water extraction system is implemented, its performance and effectiveness shall be
evaluated on at least a quarterly basis. The frequency of monitoring may be reduced, with EPA approval.
The evaluation shall be designed to determine the effectiveness of the ground water extraction system
with respect to the following:
1. Horizontal and vertical extent of the plume(s) and contaminant concentration gradients;
2. Rate and direction of contaminant migration;
3. Changes in contaminant concentrations or distribution over time; and,
4. Effects of any modifications on the ability of the extraction system to achieve containment.
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Ground water extraction will be monitored and adjusted as warranted by the performance data collected
during operation. Modifications to the ground water extraction system may include any or all of the
following:
1. At individual wells where containment has been attained, pumping rates may be adjusted
to achieve the greatest efficiencies;
2. Alternating pumping at wells to eliminate stagnation points;
3. Pulse pumping to allow aquifer equilibration and to allow adsorbed contaminants to
partition into ground water; and,
4. Additional extraction wells may be installed at EPA-approved locations to facilitate or
accelerate containment of the contaminate plume and help ensure eventual achievement
of ground water remediation goals.
10.1.1.2 Improvement to Gypsum Decant System (Alternative S4B)
This element of the selected remedy utilizes engine Jring controls to reduce the volume of water on the
surface of the gypsum stack, which is a contributor to ground water contamination. Improvements to the
water decant system will increase the flow rate of water returned to the phosphoric acid plant from the
stack, and will consequently reduce the volume of water on top of the stack. This in turn is expected to
further reduce seepage to ground water and increase the stability of the stack. A variety of potential
decant improvements are under evaluation ranging from siphon systems to more complex capture and
drain systems. Improvements to the decant system are considered to be part of Don Plant operations,
and as such, design of the system will be part of the ongoing process of optimization of the plant water
balance performed by Don Plant personnel. Exact details of the system would be developed based on
operational considerations at the time of implementation.
10.1.1.3 Ground water Monitoring and Evaluations (Alternative S4B)
Ground water monitoring and evaluation shall be conducted as part of the cleanup remedy for this OU
to determine the effectiveness of the extraction system and other source control measures in reducing
the contamination in the Plant area and preventing migration of contaminants to the off-plant area. A
surface and ground water monitoring plan shall be submitted including a quality assurance program plan
and a sampling plan for EPA approval during the remedial design. At a minimum, the monitoring program
shall include semiannual sampling of shallow,and deep aquifers and surface water springs.whose source
is the shallow aquifer.and an annual evaluation of monitoring data.
10.1.2 Air (Alternative S4EJ)
Reduction of fugitive emissions from current roads on the face of the gypsum stack will be accomplished
by constructing a stable road surface over the gypsum. This will be implemented by placing a gravel
road-base over the permanent roads on the stack. The placement of the road-base would be preceded
by rough grading, compacting the gypsum road surface and the installation of a woven stabilization
geofabric. The geofabric would prevent the gravel from being pushed into the gypsum and prevent the
gypsum from migrating through the gravel and back to the road surface. This system will create a barrier
between vehicle traffic and the gypsum and should also reduce wind and water erosion of the gypsum
on the road surfaces.
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10.1.3 Soils and Solids (Alternative S4B)
The selected remedy for the Dewatering Pit is to excavate solids (primarily phosphate ore residue),
dispose of the excavated material on the gypsum stack and cover the excavated area with soil and
vegetation. Similar action will be taken at the East Overflow Pond, except the area will be covered with
a new double lined surface impoundment for collection of non-hazardous plant water.
The selected remedy also combines a variety of institutional controls for ongoing Don Plant operations.
Specific details of these components are as follows:
10.1.3.1 Worker Safety Programs (Alternative S4B)
This element involves the addition of an education component to inform workers of the potential health
hazards at the facility which are the focus of the Superfund process. An information sheet shall be
prepared by Simplot and included in annual health and safety training for current workers and in initial
training for new workers.
10.1.3.2 Personnel Monitoring (Alternative S4B)
Exposure to external gamma radiation was estimated by the Baseline Risk Assessment to be the
principal potential risk to Simplot workers (primarily to workers on the gypsum stack). Simplot shall
implement a program requiring gypsum stack workers to wear radiation-measuring devices which would
allow for characterization of actual exposure and reduction of uncertainties associated with this pathway.
If an unacceptable level of exposure is measured for any worker, job rotation of this worker, or other
protective measures, shall be initiated. If exposure levels are shown to be consistently below the 1 x 10"*
risk based level for the first few years, the monitoring may be discontinued upon EPA approval.
10.1.4 Land Use Controls (Alternative S4B)
Simplot shall implement legally enforceable land use controls that will run with the land (i.e., deed
restrictions, limited access, well restrictions and/or well head protection) to prevent ingestion of ground
water with COCs above MCLs or RBCs. These controls will remain in place as long as the ground water
exceeds MCLs or RBCs.
Simplot shall also implement legally enforceable land use controls that run with the land in the form of
deed restrictions to eliminate the possibility for future residential use of the Simplot Plant Area.
10.1.4.1 Construction of Radon-Resistant Buildings (Alternative S4B)
The areas where gross alpha activities were measured above the soil screening level in subsurface soil
are shown in Table 4. For these areas, land use controls shall require any future office buildings to be
constructed using the radon controlling methods specified in the document "Radon Prevention in the
Design and Construction of Schools and Other Large Buildings" (EPA/626/R-92/016, 1994). Following
construction, and annually thereafter, the indoor air shall be tested for radon. If the radon activity
exceeds either 4 pCi/l. as specified in "Citizens Guide to Radon" (EPA 1992). or any promulgated
standard in effect at the time of these future sampling events, additional controls shall be implemented
to reduce the radon activity below the target level or promulgated standard.
10.1.5 Off-Plant Area
The following elements of the selected remedy exist in both the FMC and Simplot Ous.
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10.1.5.1 Fluoride Monitoriing (Alternative O3)
In order to determine the levels of fluoride present and to evaluate the potential risk to ecological
receptors, a fluoride monitoring program will be implemented. The monitoring shall generally occur within
a three-mile radius of the FMC and Simplot Plants (there may be specific areas outside the three mile
radius, which may contain sensitive species or be of particular ecological or cultural value where sampling
should also occur) and shall include sampling of vegetation, soils, and appropriate biomonitors. A
monitoring plan including a quality assurance program plan and a sampling plan shall be submitted for
EPA approval during the remedial design. An evaluation of monitoring data will be conducted annually
to determine the fluoride levels and spatial and temporal trends in the environment. If levels which are
measured indicate a risk may exist, further evaluation will occur followed by source control or other
action, if necessary.
10.1.5.2 Soils (Alternative O3)
This element of the selected remedy is designed to accomplish the following two goals. The first goal
is to prevent exposure to soils which pose a 1 in 10,000, or greater, excess risk from radium-226 and the
second goal is to restrict the use of agricultural products grown on areas of the site where contaminant
levels exceed a HQ of 1 for cadmium (RME case). In order to implement this element the off-plant area
is divided into the following areas:
Areas Subject to Land Use Controls
These are areas where soil contaminant levels exceed a HQ of 1 for cadmium (RME case) and/or which
pose a 1 in 10,000, or greater, excess risk from radium-226 as shown in Figures 27 and 28. These
areas include the Interstate 83 Right-of-Way (51 acres); Chevron Tank Farm (20 acres); City of Pocatello
Property (326 acres); a portion of the land owned by a private party named R. Rowland, and a portion
of BLM lands to the SW of the FMC facility. In this area the PRPs shall implement legally enforceable
land use controls (purchase of a recorded easement with accompanying deed restriction) restricting the
use of agricultural products grown thereon for human consumption due to the presence of cadmium in
soils. For those areas contaminated with radium-226 legally enforceable land use controls shall be
implemented to prevent future residential use.
Areas Subject to Company Monitoring for Residential Development
This area as shown in Figure 29 was not found to exceed the criteria established for the imposition of
Land Use Controls but was either close enough to the threshold, or adjacent to lands that exceeded the
threshold, to warrant notification to current and future property owners if residential use is likely to occur.
In this area the PRPs shall monitor property use for residential development and inform residential
property owners of potential human health risks associated with consumption of homegrown fruits and
vegetables due to the presence of cadmium in soils. Similar restrictions on use of agricultural products
could be implemented on such areas, as necessary.
In conjunction with this monitoring and land use controls described above, a test program shall be
developed to evaluate actual uptake into produce which may be grown by residents in the affected off-
plant areas. A monitoring plan including a quality assurance program plan and a sampling plan shall be
submitted for EPA approval during the remedial design. Cadmium concentrations in the soil and produce
shall be measured over multiple growing seasons. The results of the test program will be used to
determine if monitoring and land use controls are still required or if any additional action is necessary to
prevent potential health risks associated with consumption of homegrown fruits and vegetables.
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10.1.5.3 Ground water Monitoring
Ground water monitoring and evaluation in the off-plant area shall be conducted as part of the cleanup
remedy to: (1) determine the effectiveness of the Plants' source control measures, (2) insure
contaminants are not migrating into the off-plant area, and (3) insure that the remedy remains protective
of human health and the environment. A surface and ground water monitoring plan shall be submitted
including a quality assurance program plan and a sampling plan for EPA approval during the remedial
design. At a minimum, the monitoring program shall include quarterly sampling of shallow and deep
aquifers and surface water springs whose source is the shallow aquifer and a semiannual evaluation of
monitoring data.
10.1.6 Estimated costs for the Simplot OU
The total estimated cost of the selected remedy in the Simplot OU is shown below. These costs are
estimated and are considered to be accurate to within -30% to +50%. Costs are described using the
present worth methodology with a discount rate equal to 5 percent. The cost estimate includes direct and
indirect capital costs, as well as annual operations and maintenance costs.
Estimated Capital Costs: $1,683,000
Estimated O&M Costs: S192\00b
Estimated Total Costs: $4,571,000
10.2 FMC Operable Unit
10.2.1 Contaminated Ground water (Alternative F4/F4A)
10.2.1.1 Ground water Monitoring and Evaluation
Ground water monitoring and evaluation shall be conducted as part of the cleanup remedy for this OU
to determine the effectiveness of the source control measures in reducing the contamination in the Plant
area. A surface and ground water monitoring plan including a quality assurance program plan and a
sampling plan, shall be submitted for EPA approval during the remedial design. At a minimum, the
monitoring program shall include semiannual sampling of shallow and deep aquifers and surface water
springs whose source is the shallow aquifer. A comprehensive evaluation of monitoring data will be
conducted annually.
Ground water monitoring will continue and be integrated, to the extent practicable, with the RCRA ground
water monitoring program. EPA will periodically review ground water data with the following goals: (1)
insure the source control measures at the old phossy waste ponds, calciner solids, and railroad swale
are effective, (2) Insure there are no new sources of contamination from existing or new hazardous waste
surface impoundments or landfills, (e.g., Pond 9E, Phase IV Ponds, Pond 15S, Pond 8E and the lined
calciner ponds), and (3) confirm eventual achievement of MCLs or RBCs. Based on these goals EPA
will determine if additional steps are necessary in order to insure the remedy remains protective and
ground water is returned to beneficial uses. As stated in the 1991 Region 10 Memorandum of
Understanding Between the RCRA and CERCLA programs for the EMF Site7, selection of an alternative
7 If remedial activities conducted pursuant to the NCP at a RCRA facility address only a portion of
the units or releases at the facility requiring remediation, the permit would address any such remaining
corrective action requirements pursuant to subpart S.
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under CERCLA does not preclude more stringent monitoring or corrective actions under RCRA to prevent
further and/or future contamination.
10.2.1.2 Contingent Ground water remedy (Alternative FSB)
This element of the selected remedy for ground water is a contingent ground water extraction system.
Extraction, if needed, will occur at the locations and rates which will be appropriate to ensure that the
contaminated ground water does not migrate beyond Company-owned property and into adjoining
springs or the Portneuf River. Containment of contamination shall be achieved via hydrodynamic controls
such as long-term ground water gradient control provided by low level pumping. Extracted ground water
shall be treated and recycled within the plant to replace unaffected ground water that would have been
extracted and used in plant operations.
FMC shall monitor, on a quarterly basis, contaminant levels in the shallow aquifer and nearby springs
along the downgradient margin of the current plume. This data shall be evaluated for changes in the
concentrations of key parameters (intra well comparisons). Increasing trends in these wells shall trigger
resampling to confirm the change(s). If the increase is verified, additional interpretation shall be
conducted as directed by EPA. The trigger of the contingency extraction system will be based on
evaluations of "clean* wells and nearby springs beyond the plume. Constituent levels in "unimpacted"
wells will be compared to MCLs, RBCs, or Aquatic criteria levels (surface water at springs), whichever
is more stringent. The above evaluations shall include statistical methods for both intra well comparisons
and comparisons with MCLs as described in the 1989 Interim Guidance on Statistical Analysis of Ground-
Water Monitoring at RCRA Facilities and in the 1992 Addendum to the Interim Final Guidance. The final
determination of plume expansion will be made by EPA, in consultation with IDEQ and the Tribes, and
will depend on, (1) expert knowledge of the ground water system at the EMF Site, and (2) statistical
results from monitoring wells and springs from which levels of contamination can be measured.
Ground water extraction, if required, shall consist of installing extraction wells in the northern portion of
the FMC plant, and extracting ground water from the shallow aquifer at a rate sufficient to capture the
contaminated ground water in which concentrations of COPCs exceed MCLs or RBCs. Extracted ground .
water would be treated prior to discharge or reuse within the Plant. Bench-scale and/or pilot testing will
be required during treatment plant design.
To reduce the time needed to install a ground water extraction system, the needed technical data and
information shall be gathered, and the design drafted, during the general site remedial design phase.
Ground water extraction, if necessary, shall be periodically monitored and adjusted as warranted by the
performance data collected during operation. Modifications to the ground water extraction system may
include any or all of the following:
1. At individual wells where containment has been attained, pumping rates may be adjusted
to achieve the greatest efficiencies;
2. Stagnation points may be eliminated by using alternating pumping;
3. Pulse pumping may be used to allow aquifer equilibration and to allow adsorbed
contaminant to partition into ground water; and,
4. Additional extraction wells may be installed at EPA-approved locations to facilitate or
accelerate containment of the contaminate plume and help ensure eventual achievement
of ground water remediation goals.
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The contingent ground water remedy shall insure that the contamination in the shallow aquifer does not
spread any further and institutional controls will ensure that the shallow contaminated aquifer is not used
for drinking purposes now or in the future.
10.2.1.2.1 Ground water Extraction System Monitoring
If the ground water extraction system is implemented, its performance shall be monitored on at least a
quarterly basis. On approval by EPA, the frequency of monitoring may be reduced. The monitoring
system shall be designed to evaluate the effectiveness of the ground water extraction system with
respect to the following:
1. Horizontal and vertical extent of the plume(s) and contaminant concentration gradients;
2. Rate and direction of contaminant migration;
3. Changes in contaminant concentrations or distribution over time; and,
4. Effects of any modifications on the ability of the extraction system to achieve containment.
10.2.1.3 Point of Compliance for Ground water
For the purposes of the Superfund remedial action, the ground water cleanup levels for the Plant Area
shall be based on MCLs or RBCs. However, under certain circumstances, other regulatory authorities
may require more stringent ground water standards within the plant boundaries. Such regulatory
authorities would include, but not necessarily be limited to, RCRA, which might require ground water
corrective action as result of any releases from RCRA regulated units.
10.2.2 Soils and Solids
10.2.2.1 Capping Ponds and Calciner Solids Area (Alternative F4/F4A)
EPA's selected remedy for reducing infiltration and preventing direct exposure in the FMC OU old phossy
ponds 1S-7S, 1E-7E, 9S, and 10S and Former Calciner Pond Solids Storage Area is either installation
of a soil cover or capillary barrier cap and vegetation. Those ponds or areas which were more
extensively used and contain a greater volume of waste are expected to require a capillary barrier cap,
or equivalent, in order to reduce infiltration and provide a greater level of permanence than a soil cover.
Due to the presence of buried elemental phosphorus in some areas, the higher level of permanence
afforded by the capillary barrier cap is warranted and the additional cost is justified. A soil cover and
vegetation may be sufficient in areas which were-used for a relatively short period of time and/or contain
significantly lower volume of waste. Decisions on which cap/cover is applied at each of the old phossy
ponds and calciner solids area will be made by EPA during the course of the remedial design using all
relevant information available at that time.
Soil Cover, grading, and vegetation, where applicable, shall consist of backfilling low areas (e.g., former
Ponds 1E and 4E) to bring them up to the surrounding grade levels, and then shaping the surface to
enhance surface drainage and reduce the potential for infiltration. Design and performance criteria shall
be based on achieving a reduction in infiltration (to at least 1x10'7 cm/sec), prevention of incidental
ingestion, and reduction of exposure to radiation. A surface soil cover of at least 12 inches shall be
placed over the backfill and vegetation suitable to the area and climate shall be established and
maintained. In low areas where surface water flow must be directed over old pond areas, concrete,
gunite, or asphaltic concrete, or culverts shall be added to enhance runoff. Runoff shall be directed
70
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toward natural drainage collection areas in the northern and northwestern portions of the FMC OU. The
drainage collection areas shall be constructed in a manner to avoid ponding of surface runoff water.
Capillary Barrier Caps, where appropriate, shall consist of a minimum of 2 feet of vegetated native top
soil underlain by a 6-inch gradational layer and 18 inches of well sorted coarse material (slag or river
gravel). Design and performance criteria shall be based on achieving a reduction in infiltration (to at
least 1x10'7 cm/sec), prevention of incidental ingestion, and reduction of exposure to radiation.
FMC shall maintain the integrity and effectiveness of the caps and soil covers, including making repairs
to the covers as necessary to correct the effects of settling, subsidence, erosion, or other events. Ponds
not subject to the remedial actions of this ROD remain subject to other requirements and regulations.
10.2.2.2 Railroad Swale (Alternative F4/F4A)
FMC shall install and maintain a synthetic liner in the eastern portion of the railroad swale to reduce
infiltration of surface water and leaching potential. FMC shall modify and extend the existing liner at least
850 feet to the east. The liner shall have, at a minimum, a 30-mil PVC liner and be covered by a
protective sand layer with a minimum thickness of 6 inches. Design and construction shall conform with
work conducted on the existing liner in the western portion of the railroad swale and shall include
sampling during design for potential generation of gases which could affect liner performance. FMC shall
maintain the integrity and effectiveness of the liner and final cover, including making repairs to the cover
as necessary to correct the effects of settling, subsidence, erosion, or other events.
10.2.3 Land Use Restriction:;
FMC shall implement legally enforceable land use controls that will run with the land (i.e., deed
restrictions, limited access, well restrictions and/or well head protection) to prevent ingestion of ground
water with COCs above MCLs or RBCs. These controls will remain in place as long as the ground water
exceeds MCLs or RBCs.
FMC shall also implement legally enforceable land use controls that run with the land in the form of deed
restrictions to eliminate the possibility for future residential use of the FMC Plant Area.
10.2.3.1 Construction of Radon Resistant Buildings (Alternative F4/F4A)
At the FMC Plant, land use controls shall require any future office buildings to be constructed using the
radon controlling methods specified in the document "Radon Prevention in the Design and Construction
of Schools and Other Large Buildings" (EPA/626/R-92/016,1994). Following construction and annually
thereafter the indoor air shall be tested for radon. If the radon activity exceeds either 4 pCi/l, as specified
in "Citizens Guide to Radon" (EPA 1992), or any promulgated standard in effect at the time of these
future sampling events, additional controls shall be implemented to reduce the radon activity below the
target level or promulgated standard.
10.2.4 Off-Plant Area
The following elements of the selected remedy exist in both the FMC and Simplot OUs.
10.2.4.1 Fluoride Monitoring (Alternative O3)
In order to determine the levels of fluoride present and to evaluate the potential risk to ecological
receptors a fluoride monitoring program will be implemented. The monitoring shall occur within a three-
mile radius of the FMC and Simplot Plants (there may be specific areas outside the three mile radius,
71
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which may contain sensitive species or be of particular ecological or cultural value where sampling should
also occur) and shall include sampling of vegetation, soils, and appropriate biomonitors. A monitoring
plan including a quality assurance program plan and a sampling plan shall be submitted for EPA approval
during the remedial design. An evaluation of monitoring data will be conducted annually to determine
the fluoride levels and spatial and temporal trends in the environment. If levels which are measured
indicate a risk may exist, further evaluation will occur followed by source control or other action, if
necessary.
10.2.4.2 Soils (Alternative 03)
This element of the selected remedy is designed to accomplish two goals. First, to prevent exposure to
soils which pose a 1 in 10,000, or greater, excess risk from radium-226 and secondly to restrict the use
of agricultural products grown on areas of the site where contaminant levels exceed a HQ of 1 for
cadmium (RME case). In order to implement this element the off-plant area is divided into the following
areas:
Areas Subject to Land Use Controls
These are areas where soil contaminant levels exceed a HQ of 1 for cadmium (RME case) and/or which
poses a 1 in 10,000, or greater, excess risk from radium-226 as shown in Figures 27 and 28. These
areas include the Interstate 86 Right-of-Way (51 acres); Chevron Tank Farm (20 acres); City of Pocatello
Property (326 acres); a portion of the land owned by a private party named R. Rowland, and a portion
of BLM lands to the SW of the FMC facility. In this area the PRPs shall implement legally enforceable
land use controls (purchase of a recorded easement with accompanying deed restriction) restricting the
use of agricultural products grown thereon for human consumptions due to the presence of cadmium in
soils. For those areas contaminated with radium-226 legally enforceable land use controls shall be
implemented to prevent future residential use.
Areas Subject to Company Monitoring for Residential Development
This area is shown in Figure 29 and was not found to exceed the criteria established for the imposition
of Land Use Controls but was either close enough to the threshold, or adjacent to lands that exceeded
the threshold, to warrant notification to current and future property owners if residential use is likely to
occur. In this area the PRPs shall monitor property use for residential development and inform residential
property owners of potential human health risks'associated with consumption of homegrown fruits and
vegetables due to the presence of cadmium in soils. Similar restrictions on use of agricultural products
could be implemented on such areas, as necessary.
In conjunction with this monitoring and land use controls described above, the PRPs shall develop a test
program to evaluate actual uptake into produce which may be grown by residents in the affected off-plant
areas. A monitoring plan including a quality assurance program plan and a sampling plan shall be
submitted for EPA approval during the remedial design. Cadmium concentrations in the soil and produce
shall be measured over multiple growing seasons. The results of the test program will be used to
determine if monitoring and land use controls are still required or if any additional action is necessary to
prevent potential health risks associated with consumption of homegrown fruits and vegetables.
72
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10.2.4.3 Ground water Monitoring
Ground water monitoring and evaluation in the off-plant area shall be conducted as part of the cleanup
remedy to: (1) determine the effectiveness of the Plants' source control measures, (2) insure
contaminants are not migrating into the off-plant area, and (3) insure that the remedy remains protective
of human health and the environment. A surface and ground water monitoring plan shall be submitted
including a quality assurance program plan and a sampling plan for EPA approval during the remedial
design. At a minimum, the monitoring program shall include quarterly sampling of shallow and deep
aquifers and surface water springs whose source is the shallow aquifer and a semiannual evaluation of
monitoring data.
10.2.5 Estimated Cost for FMC Operable Unit
The total estimated cost of the selected remedy is shown below. These costs are estimated and are
considered to be accurate to within -30% to +50%. Costs are described using the present worth
methodology with a discount rate equal to 5 percent. The cost estimate includes direct and indirect
capital costs, as well as annual operations and maintenance costs. Costs reflect a range from grading
and soil covers to capillary barrier cap and implementation of the contingent ground water extraction
system.
Estimated Capital Costs: $3,313.000 to $7,176.000
Estimated Annual O&M Costs:$121,200 to $837,200
Estimated Total Costs:$4,848,000 to $20,660,000
10.3 Five Year Review Requirements
Because this remedy will result in hazardous substances remaining on site above heath-based levels,
a review will be conducted within five years after commencement of remedial action to ensure that the
remedy continues to provide adequate protection of human health and the environment. The review will
include, at a minimum, evaluation of the following:
Ground water
• Review Simplot extraction system operation and maintenance records along with ground water
monitoring data to confirm the effectiveness of the system and achievement of the following
goals: (1) contain the migration of COCs from the phosphogypsum stack and reduce the area!
extent of shallow ground water contamination within the Plant Area in excess of MCLs or RBC.
and (2) prevent the migration of COCs above MCLs or RBCs into the off-plant area.
• Review and evaluate all ground water monitoring data to: (1) determine the effectiveness of the
Plants' source control measures in reducing COCs throughout the site, (2) insure contaminants
are not migrating into the off-plant area, and (3) insure that the remedy remains protective of
human health and the environment.
• Determine if/when remediation goals have been achieved, and if not. that institutional controls are
still in place to prevent human exposure to contaminated ground water.
Soils
• Evaluate current land use in the off-plant area and the effectiveness of land use controls to
restrict property use and inform residents of the potential risks associated with consumption of
homegrown fruits and vegetables.
73
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• Evaluate the integrity of the caps and soil covers to ensure their effectiveness.
• Evaluate the effectiveness of surface grading and runoff controls to reduce potential infiltration
in capped/covered areas.
Plant Areas
• Evaluate FMCs and Simplots compliance status with environmental (such as the CAA, IDAPA,
CWA, and RCRA) and worker health and safety requirements to ensure that the remedy remains
protective.
• Determine if Plant closure has occurred or is planned, and if so, verify that any required/planned
closure procedures are protective.
• Determine the status of any RCRA closures at FMC and review the closure procedures and areas
to ensure that the remedy remains protective.
• Determine if institutional controls are in place to prevent residential use of Plant Areas and control
radon in buildings.
• Evaluate worker safety program and personnel monitoring to ensure that the remedy is protective
of workers.
Aj£
• Compare fluoride monitoring results with the findings of the ecological risk assessment and any
other available information to insure that the remedy remains protective of the environment.
• Review any relevant information related to the air pathway to ensure the remedy is protective.
11.0 STATUTORY DETERMINATIONS
EPA's primary responsibility under CERCLA is to ensure that remedial actions are undertaken which
protect human health, welfare, and the environment. In addition, Section 121 of CERCLA, 42 U.S.C. §
9621, establishes cleanup standards which require that the selected remedial action complies with all
ARARs, unless such requirements are waived in accordance with established criteria. The selected
remedy must be cost effective and must utilize permanent solutions, alternative treatment technologies,
or resource recovery technologies to the maximum extent practicable. The following sections discuss
how the selected remedy meets these requirements.
11.1 Protection of Human Health and the Environment
The selected remedy is protective of human health and the environment, complies with Federal and State
requirements that are legally applicable or relevant and appropriate to the remedial action, and is cost-
effective. The remedy will be protective of exposure to ground water through implementation of
Institutional Controls to ensure no human exposure to contaminated ground water, and a monitoring
program to ensure that the contaminated plume does not spread and contaminant concentrations
eventually decline. Ground water extraction at Simplot and source controls (soil excavation and capping)
at both Plants will reduce the release and migration of COCs to the ground water and eventually restore
ground water to meet all RBCs or MCLs for the COCs. Source controls will also have the added benefit
of preventing ingestion or inhalation of soils containing COCs at levels that pose estimated excess risks.
74
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Personnel monitoring and source controls will also prevent external exposure to radionuclides in soils at
levels that pose excess cancer risks.
Legally enforceable land use controls will reduce potential exposure to radon that would occur in future
buildings constructed within the Plant Areas. They will also prevent future consumption of homegrown
produce grown in areas of the site where soil constituents levels result in a potential noncarcinogenic risk
exceeding a HQ of 1 and prevent external exposure to radium-226 in soils at levels that pose cumulative
estimated excess risks above 1 x 10"V
Monitoring ground water and fluoride will insure that the remedy remains protective of human health and
the environment. Air emissions from the Plants are to be controlled by other Federal and State regulatory
programs however, the final remedy for the site requires a periodic reevaluation of the air pathway to
ensure that the remedy remains effective and is protective of human health and the environment
Because this remedy will result in hazardous substance remaining on-Site above health-based levels,
a review will be conducted within five years after commencement of remedial action to ensure that the
remedy continues to provide adequate protection of human health and the environment.
11.2 Applicable or Relevant and Appropriate Requirements
The selected remedy will comply with all chemical, action, and location-specific federal and state ARARs.
No ARAR waivers will be used. Specifically:
40 C.F.R. Part 141. Safe Drinking Water Act. MCLs, and non-zero MCLGs are relevant and
appropriate for the ground water at the site.
Clean Water Act Water Quality Criteria 40 CFR Part 131. This regulation sets criteria for
developing water quality standards based on toxicity to aquatic organisms and human health.
This regulation would be applicable if the contingent ground water remedy was implemented and
there was direct discharge to surface waters. These regulations are relevant and appropriate for
ground water which discharges to surface water as a non-point source such as at the springs.
Idaho Ground Water Standards (IDAPA Sec. 16.01.02.299). Protects ground water for beneficial
uses, along with the Idaho Antideoradation Policy (IDAPA Sec. 16.01.02.051). which requires that
existing water uses and water quality be maintained and protected. These ARARs will be met by
source control and ground water extraction.
Clean Water Act National Pollutant Discharge Elimination System 40 CFR Part 122. 124. 136.
This regulation requires best management practices and other efforts to minimize pollutants in
discharges to surface water. These regulations would be applicable if the contingent ground
water remedy were implemented. Treated ground water will be discharged in a manner which
complies the substantive requirements of the above-mentioned ARAR, or in compliance with
FMC's NPDES permit, whichever is more stringent.
Clean Air Act. 42 U.S.C. 7401 et seq.) National Primary and Secondary Ambient Air Quality
Standards. 40 C.F.R. Part 50: CAA National Emissions Standards for Hazardous Air Pollutants.
40 C.F.R. Part 60: CAA New Source Performance Standards. 40 C.F.R. Part 61. These
regulations establish standards for air quality to protect public health and welfare and establish
emissions standards for designated hazardous air pollutants.
75
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Resource Conservation and Recovery Act 42 U.S.C. 6901-6987 40 CFR 261-264: 268. These
regulations define when a solid waste is as hazardous wastes and the requirements that must be
met by generators, transporters, and for treatment, storage and disposal of those wastes,
including land disposal restrictions.
IDAPA 16.01.01. This regulation contains primary and secondary air quality standards for fluoride
concentrations in ambient air which result in total fluoride content in vegetation used for feed or
forage. The standards are relevant and appropriate if agricultural feed sources were grown on
the site.
The policy, guidance, and regulations which are not ARARs but were nevertheless considered in the
selection of the remedy, or which impact the remedy includes the following:
Occupational Safety and Health Act (OSHA), 29 U.S.C. 651; the implementing regulations under
OSHA, 20 C.F.R. Parts 1910 and 1926. These regulations must be complied with during all
remedial activities.
"Radon Prevention in the Design and Construction of Schools and Other Large Buildings"
(EPA/626/R-92/016. 1994) and "Citizens Guide to Radon' (EPA 1992). These documents
provide guidance on controlling radon in future buildings at the site.
EPA's Environmental Radiation Protection Standards for Management and Disposal of Spent
Nuclear Fuel, High-Level and Transuranic Radioactive Wastes (40 CFR 191) and EPA's National
Emission Standards for Hazardous Air Pollutants (40 CFR 61) set standards equivalent to a risk
of approximately 3 x10~*. These documents provide guidance on the level of protecth/eness from
radiation that have been set by other programs.
11.3 Cost Effectiveness
The selected remedy affords overall effectiveness proportionate to its costs. The selected source control
remedy at FMC and Simplot is cost effective because it will achieve most cleanup goals without adverse
effects on the plant operations. The no action alternative and other more limited alternatives would not
achieve the cleanup goals. The use of impermeable caps at FMC and a liner on the Gypsum stack at
Simplot would increase costs over $100 million without achieving the goals much more quickly than
natural recovery after source control.
11.4 Utilization of Permanent Solutions and Alternative Treatment Technologies to the
Maximum Extent Practicable
The selected remedy utilizes permanent solutions and alternative treatment (or resource recovery)
technologies to the maximum extent practicable for this site. Source control at FMC and ground water
extraction at Simplot is expected to eliminate and/or reduce the source of the problem such that the
shallow aquifer will recover naturally to its beneficial use.
11.5 Preference for Treatment as a Principal Element
The selected remedy utilizes alternative treatment (or resource recovery) technologies to the maximum
extent practicable for this site. However, because treatment of the remaining threats of the site was i jt
found to be practicable, the selected remedy does not satisfy the statutory preference for treatment -s
a principal element.
76
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12.0 Documentation of Significant Differences
Subsequent to issuing the Proposed Plan, EPA reviewed public comments. In response EPA has re-
evaluated the ground water extraction for hydraulic control for the FMC Plant and made a change which
is discussed below. This change is a logical outgrowth of the information available to the public in the
Proposed Plan and the RI/FS reports. An additional public notice or public comment period was
determined not to be necessary.
12.1 FMC Operable Unit Extraction and Treatment
The Proposed Plan included an element for hydraulic control of the contaminated plume. After further
review of the data and consideration of public comments, EPA has determined that this action is not
required, at this time, to protect public health and the environment. Current evidence suggests that
ground water associated with the FMC Plant is not spreading and contaminant concentrations are not
increasing. There are currently no human exposures to ground water contamination originating from the
Plant and institutional controls will prevent any potential future exposures. The extraction for hydraulic
control would remove a greater volume of contaminants from the ground water but at a higher cost and
with only marginal reductions in the time to achieve the cleanup goals. The implementability of the
extraction for hydraulic control is also questionable due to the lack of acceptable alternatives for disposal
of the ground water.
However, the levels and locations of contaminants in ground water will require careful monitoring, and
ground water extraction and treatment could be necessary in the future. Therefore, the selected remedy
includes a contingent ground water extraction and treatment system with conditions for implementation.
If, at any time, plume expansion8 is detected which could pose a threat to human health or the
environment, ground water extraction will be immediately implemented to contain the area of ground
water contamination.
8The final determination of plume expansion will be made by EPA and will depend on; (1) expert knowledge
of the ground water system at the EMF Site; and. (2) statistical results from monitoring wells and springs from which
levels of contamination can be measured.
77
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APPENDIX A
ADDITIONAL FIGURES AND TABLES
RECORD OF DECISION
FOR
FINAL REMEDIAL ACTION
EASTERN IMICHAUD FLATS SUPERFUND SITE
POCATELLO, IDAHO
A-l
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A-6
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'
SIMPLOT SUBAREA
EASTERN MICHAUO FIATS
POCATEU.O. IDAHO
FEASIBILITY STUDY
CONTOURS Ot DEEPER
GROUNDWATER ELEVATIONS
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Moaei (Appcnai- KI »is ji»oic
lhes« panicle >r*:Ks.
• •- : : 5- : :• ' \ ' ^ v .
_....•-••• ': .; /t_. • • '• - "V/-..
'•I :: • 7.- -• ,1. ' j '! " .
• • ....'. I •.'.:•
R't-JMOri RAT-J^F
D • < 1 "J 1 J v, \. I ' i • » 1 * "O 1—
• :. '• ! i.. 1 - .-' ..-•-.•
: - i • • .
BEC^TEL ENVIRONMENT*!.. INC.
EASTERN MICHAUD FLATS
POC4TELLO. IP* HO
Effecis oj Pltn; ?rodu>Uto Wt£s
On Doep Gre>Bathvti*r FlowpaL^
^^m XDimiTfm
$j) 313-;
C"»«-^>* *»-.
Ficure 10
*-8
-------
n«(ani«ji: USGS loafw Fans and Create*) TopognoNe Maps. 1962-1:2SO.OOO scnes
N
J
EASTERN MICHAUO FLATS
POCAT6U.O. IDAHO
FEASIBIUTY STUDY
MAJOR SURFACE WATER
FEATURES IN THE REGION
FIGURE U
-------
Pocatello. Idaho
N
STABILITY x
• -3 4-6 7-»0 11-16 17-ZI 2:2-99
(5 «) (JO m)(29 «)<2» •)(? •) 01 •)
WIND SPEED SCALE (KNOTS)
NOTE - WIND DIRECTION is THE
DIRECTION WIND is BLOWING FROM
SOURCE: Bechlel 1994.
Figure 12. WIND ROSE, POCATELLO AIRPORT, 1984 TO 1989
A-10
recycled paper
-------
000-3+- > OZJ-i*. •/• "-J-
• '" f..\ v>X-i' ^^S^/;^?S
'
—•-.y t'--rr*-A-~
• X 1« 1 >«v —^
,^<:r;,i.«\ "••-r- \
K:^,^
30" 6000 FEET
SOD 1000 1500 METERS
BKMIEL tMVBUHiaeNTJU. MC.
EASTERN MCHAUD FLATS
POCATELUD, IDAHO
-------
H- +
Key to Cadmium (mg/kg)
100
50
5
1.9
EXPLANATION:
Svnpw Lootnn
*>
^
OAF Property Boundary
2500 5000 ft
BECHTELENVffiONMENTAmNC.
EASTERN MICHAUO FLATS
POCATELLO. tDAHO
SurfjCt Soil!
FIGURE 17
A-12
-------
JtiQ-- :^?*':>.-;-r-fy^.--:';^-:/-v -/"iilxtS^WSS*1 r-^Mttfol-S!*?--' *'-'•". •••• • ~
m^^^^^^^imS^^^^^ • • &
i--:;^'^:x?<^M^--v^^:S^^^;'i^^ •" " _
BECHTEL ENVIRONMENTAL, INC
Muoride Concentrations ID
Surface Soib
^-^C t •'^^^Wt •V-'-"-r f " •'-••••• J "•• ;^-^^: <"^X>-. -•:
-\^\ x\S\-,,..: : ; , ...^ J;l?f.: ,
Z137Z
FIGURE 16
I •
A-13
-------
TANK-FARM MONfTORING WELLS •
O Shallow monitoring well
© Deep monitoring wen
«> Water supply weU
• Production wen
H Abandoned shallow monitoring we!
J8 Abandoned deep monitoring weO
• Abandoned production wefl
EMF Property Unes
IRR
TANK-FARM • ' li
----- .xf --------
bsosta
i
i FMC SUBAREA
^-•^^ i ! 523
WILLIAMS^* ;8
2* J.,.-^.;£f\'-' ; ^""-iaoe q^ /
'^^^™...i« /;.!'• g» 139 «y*®ffi8638''// iill^'l-y
. -J—\'l^ ."^B9 ^yc^>sl-.*S!:^^^Sp^^ira/ ' 0142 i.^ / f-4
FMC SUBAREA
TW-10S .-' '
° ,± '
.-V- ••.
.4" .
<•'" IDAHO-POWER
. __
i
' /•• ;
..^~j-^ .1 •• i
INDIAN SPRINGS
JTKJl/TFARM
v-~^^ *L ^A
•v.. •-'
•j !-7Tx'v;T.-.->.. vj.
- "" "
i~i-u GHPEM
1 FIGURE |9
-------
UOMPACTED GflOUKIWATEfl
OUALITV (WEtl. 1»4 UAXIUUU VALUE)
HI m»1
0.017 n«1
IS m»l
0.005 m»1
OJ mffl
OJ3 a«l
NO m*
2.12 ms*
0.17 mg/l
0.1 mgll
•1.2 m«1
n mtfl
OJKB mg«
Flow Toward Well 111
(See Figure 4.4-11)
MIXED GHOUMOWATO)
OUAUTY (WEU 111 UAXIUUU VAUO
AhlV*y JS3 nvl
Ao«™c O.OSS me/1
CnorxM jsj mgi
Coo« 0.021 nBl
0.1 IT^
0.113 n«l
i >«l
G
> '• '. -, r'.n' ' •' '^'/••'
'•> -: • £& ^ & >&<& •••"' ;
.x.. «- .x 4* AA ^- ,." v .. .
i •--...• i
:r<
"-.•' 1 ' '•' ••
1
:. \
Otol* M n>»
CUM (UX) «0«
An)* U >ol
UMKi U *0I
ita^BM u ^n
MM |U ^1
O1M«"^»M1 HJ «B«
•BMkn a ^i
£T £2
*~*» OXBD •«<
U
BeCWTSL OflnROHMEKTAl, MC.
EASTERN WCHAUO FLATS
POCATELLO, IDAHO
Gnodnicr Ft** to Ik* Soolkwaun
AnttttttFMCFMflky
^%> — .--i.
l«9/ nm
f i_ri_
ncou 21
-------
EASTERN MCHAUD FIATS
POCATEU.O. tDAHO
-------
v moK :*xx*t. out
E"~ureMediuin
Receptors and Routes
ol Exposure
FMC/Slmplot
Ore Receiving/Storage/Handbng Areas':
Sucks and Vents: Operating Area:; Punt Roads
FMC
Slaj Prie: Waste PJ« 8S;
FMC
inactive Pond t E: inactive Pond *E: Bannock Paving; Pressy waste and
Precjptator Slurry fhpwrvj Ctaanout Araas: Waste Pies Soon ol Calonef
Ponds: Cateiner Pond Sedment Area; Catcirier taes Area: Undfril Anujs
Simplot
Sokd loaaom Areas: Farmer Ore PN
Simplot
n*c~
Pond 8E (Vnwtl 1); Pond «6 (WUun);
Panda 11S.1JS.11S. and 14S (WMUM);
Pond S3 fnlUtTf. PCM 1SS (WUUt),:
Pond "S Recovery Preoen (WMUM):
OM CaWnaf Ponds (MrnoricaO: Pond 9S (MolorxaJ): Panda 1 S • 7S
(H«»j«n^aO«cMWKO»^l«*r»jP«Fcm«Pilr>,Tlrt* Cortannent;
Oparaling Araas: Forme> Coelng Pond: watar Reoaini Ttiixanars: Salvage
and Storaga Anwt bngabon watar
Air Emissions
• Paniculate
•Gaseous
+
Use ol Waste
Materials as Fill
f
tnfltretiOiV
Pcfcoteinoft
Air
Se**^
De
position
1
Innitraiion/
PereotaUon
Ai
r
On Site
Soil
on
&
Stte
fl
Homoyiuwn
Produce.
Meat and
Dairy Products
'
Exposure
lnr,alation
Nearby Residents
C.F
Workers
C.F
Ingeslion
Dermal Contact
Eiiema) Radiation
Exposure
C, F
C.F
C.F
InQestion
D&rfnal Contact
External Rarfflliofl
Eiposure
C.F
C.F
C.F
—
injawKui
C.F
Irgestion
Dermal Contact
F
F
. —
FMC
tWWOtth
Simplol
warn Treatment Pond Enuen
(MBtoncal)
IrodentaJ
Ingeslion
Dermal Contact
Fish
Consumption
* As of September 199t.otv«»wc¥crledio tie SfTvegftaofttyn slurry term SanpWore rtccmng.
norage. Mid nanli)^ a no kxgtt • poutnal uutt d pnxulim.
~ FMC hai suBmitled • RCBA Put B tfftaaan to tw EPA when samm management ol mese umts.
C.F
C.F
C.F
KEY:
C Compete uneer current conditions
F Compete under potenLj] future condilxms
— Pathway not complete
A-17
Figure SLJ CONCEPTUAL SITE MODEL
FOR POTENTIAL HUMAN EXPOSURE
TO CONTAMINANTS FROM THE
EASTERN MICHAUD FLATS SITE
-------
7'v> * H.'^a.
\ :i"\ :
' -v\ -A
• «p|?-"|ji-''P
*
- RAOIUM-226
---- UEAO-210
------- POLONIUU-210
SCALE
1600 FEET
EASTERN MCHAUD FLATS
PCCATELLO. BAHO
STUDY
OFFSTTE EtBABFA
AREAS WHBCI
Acnvmes M BURFACC sots
EXCEED TW «T> MCREIENTAL
CAMCtBRBK LEVB.
-------
N
*r%.-^^£$
I '~s\ y 'i»-=
^»-f\ f •'^S-,-'
X 4 J •' T>*/
NPTFS;
1. CONTOURS SHOWN CORRESPOND TO
INCREMENTAL CANCER RISK OF 1CT8.
2. NO AREAS EXCEED KT8 RISK FDR
URANIUM-23B. POLOMUU-210.
LEGEND;
SOD. SAMPUNC LOCATION
AND DESGMAT1ON
RADIUU-226
LEAO-210
SOLE
==
1600 0 1600FECT
EASTERN MCHAUD FLATS
POCATELLO, OAHO
FEA3BUTY STUDY
OFFSTTE SUBAREA
ACTIVrTES M SURFACE SOILS
EXCEED THE «T* MCREMBttAL
CANCSt RgK LEVH.
~
i-19
-------
••<>•--.•,. . jT" 'I Hj •-<
S V C. .^^•'•;--%:-i-:vcmfief
NOTES:
1. CONTOURS SHOWN CORRESPOND TO
INCREMENTAL CANCER RISK OF 1(T!
2. NO AREAS EXCEED 1CT4 RISK FOR
URANIUU-238. POLONIUM-210.
AND LEAD-210.
SOIL SAMPUNC LOCATION
AND DESIGNATION
RADIUU-226
SCALE
1600 0 I600FEE7
M , ^ .'!fV ^^^-.V^1^.---;;.^ *'s ';;V,/VJ>"" r
j ' '-:.:f°^" . v-.. S'*^i.. • ' ( .-"/' • "."."' ' ••''
•Is ; \7 A ^ ^0\Vi- - , '"^ .-: .-•'" ! .
EASTERN MCHAUD FLATS
POCATELLO, DAHO
FEASEUTY STUDY
OfFSTTE SUBAREA
AREAS WHERE RAOIONUCUDE
Acnvrrcs w SURFACE SOILS
EXCEED THE Kr-> MCREMENTAL
CANCER RISK LEVEL
| FIGURE 7.T
-------
LEGEND;
"*-"
(mg/>t)
CT CMC (Tl
M CAST (T«J
EASTERN MCHAUD FLATS
PQCATELLO. PAHO
FEASBUTY STUDY
OFFSrre 8UBAREA
AREAS WHERE CADMUM
COMCEMTTUmONS M SURFACE SOU.
EXCEED LEVELS EOUVALENT TO
A HAZARD OUOTEKT OF QIC
I FIGURE 28
-------
Shaded area depicts
property subject to
residential use monitoring
CITY OP POCAUXLO
Areas where Cadmium
concentration exceed levels
equivalent to a hazard
quotient of one.
RME Case (16.9mg.kg)
EASTERN MICHAUD FLATS
POCATEU.O.OAHO
AREAS WHERE CAOMnM
OCEED LEVELS EQUIVALEWTTO
* HAZARD OUOTCNT Of ONE
29
-------
Appendix M Wastes Potentially Containing Elemental Phosphorus in Former Pond Areas
Table 1
FMC Facility - Unlined Former Ponds
Historical Summary
Pond
DOS
OS
IS
2S
When
fiuill
1954-55
1954-55
1954
1955
When Use
Ended
1956
1956
Oct. 1961
Oct. 1961
When Material
Dried Received
Cover Materials)
? Precipitator dust and NA
phossy residuals. Mixed
with ore pile and
reprocessed.
Prior to Precipitator dust and Slag
1965 - phossy residuals. Some
mixed with ore pile and
reprocessed.
1972
1972
Phossy water and phossy Slag, soil.
solids. Reclaimed to plant
twice per year.
3S Nov. 1961 Jurt 1965 Dec. 1976
Phossy water and phossy
solids Reclaimed to plant
twice per year.
Precipitator dust slurry;
slag pit water and solids;
phossy water and phossy
solids; residuals from P4
reclaim operation on ponds
IS and 2S and east end of
3S
4S Apr. 1966 Mar. 1967 Jul. 1976 Precipitator dust slurry
Slag, soil.
Capped with 3 feet of
soil, then covered with
crushed slag.
Other Notes
Site is under Mobile Shop now;
Mobile Shop constructed in 1965.
Site was a pit only, not a
"pond"; site now is a mobile
equipment parking lot.
Initially hauled in slurry truck;
pipeline installed in 1957.
P< was reclaimed to plant from
1966-1972.
Pt was reclaimed to plant twice
a year until September 1965. P<
continued to be reclaimed to
plant from 1966-1972.
Settled solids were routinely dug
out twice a year until 1965. P4
in east end was reclaimed in
1972-1976; approximately 100
feet of east end was filled with
slag after reclaiming; this area
is not capped as is the rest of
the former pond.
Capped with 3 to 6 feet
of soil.
Page 1 of 4
-------
Appendix M Wastes Potentially Containing Elemental Phosphorus in Former Pond Areas
Table 1
FMC Facility — Unlined Former Ponds
Historical Summary (ConI'd)
Pond
No.
When
Built
When Use
Ended
When
Dried
Material
Received
5S Jul. 1965
Mar. 1967 Mar. 1976 Phossy water and phossy
solids
6S Apr. 1967 Feb. 1969 Jul. 1976
7S Mar. 1969 Sep. 1970 Jan. 1980
8S
9S
Oct. 1970 Sep. 1993
1971
1974 (?) Nov. 1980
Precipitator dust slurry;
some phossy water and
phossy solids in ME corner.
Precipitator dust slurry
with phossy hot spots.
Phossy water and phossy
solids; some precipitator
dust slurry.
Precipitator dust slurry;
slag pit water and solids.
Material dried and sold.
Cover Materials!
Capped with baghouse
dust; precipitator dust
slurry; fluid bed drier
product priiis and dust;
slag; final soil cap on
top.
Capped with soil; south
end partially filled
with slag and paved
with asphalt for use as a
new slag haul road.
Two high - P« areas
capped with cement;
entire area capped with
6 to 10 feet of pit-run
slag, then three feet of
soil.
Cover design in progress.
Not capped.
Other Notes
Very difficult to dry because of
pyrophoric contents; fine solids
would not support cover weight.
New slag haul road over south
end.
New slag haul road over south
end; This site is now byproduct
ferrophosphorus stockpile,
approximately 25 feet high.
Site was raw material source for
85 P< recovery plant, built in
1982, closed in 1993.
Contents were dried in place and
about 20 to 25 feet dug out for
outside sales; small quantity
remains in place.
Page 2 of 4
-------
Appendix M Wastes Potentially Containing Elemental Phosphorus in Former Pond Areas
Pond
No.
When
Built
When Use
Ended
When
Dried
IE Apr. 1965 Fall 1982 Oct. 1980
2E Apr. 1965 Oct. 1967 1977
>
U1
3E May 1967 Sep. 1970
1980
4E May 1967 1980 Oct. 1980
Table 1
FMC Facility - Unlined Former Ponds
Historical Summary (Cont'd)
Material
Received
Phossy water and
carryover fine solids from
upstream ponds;
precipitator dust slurry
and dried slurry. Material
dried and sold.
Phossy water and
carryover fine solids from
upstream ponds. Some
material removed and
sold.
Phossy waler and
carryover fine solids from
upstream ponds.
Phossy water and
carryover fine solids from
upstream ponds;
precipitator dust slurry
overflow.
Cover Materials!
Not capped.
Site is beneath current
Phase IV ponds (8E).
Site is beneath current
Phase IV ponds (11S-
14S).
Not capped.
Other Notes
Filled with dredged precipitator
dust slurry from fluid bed drier
surge pond in fall of 1982.
Site was used for storage of
precipitator slurry fluid bed
drier product, then dug oul for
lined pond 8E construction in
1984; residual precipitator dust
sent to 4E site. Some material
was removed and sold.
Contents dug out for construction
of new lined ponds in 1980; this
site now occupied by lined ponds
US, 12S, 13S, and 14S.
Received precipitator slurry
from fluid bed drier slurry pond
in fall of 1982. Some material
removed and sold.
Page 3 or 4
-------
Appendix M Wastes Potentially Containing Elemental Phosphorus in Former Pond Areas
Table 1
FMC Facility - Unlined Former Ponds
Historical Summary (Cont'd)
Pond
No*
When
Built
When Use
Ended
5E Apr. 1968 1972-73 (?)
When
Dried
1981
6E
7E
Nov. 1968
Dec. 1969
1980-81
1980-81
1981
Material
Received
Cover Materials)
Phossy water and very Site is beneath current
minor carryover fine solids Pond 15S.
from upstream ponds.
Same as 5E.
1981 Received phossy water
only a few seasons; no
solids observed in 7E.
Same as 5E.
Not capped.
Other Notes
Dried gray settled soil (4" to 6")
placed in area just south of new
15S lined pond. New lined pond
1 cc ««v*a Vt*««ii «%*« *v.:«« ~3t«% :«
AtaSw/ »»u^ istual V4I UU9 911C Ul
1982.
Same as 5E.
Eastern ± 150 feet used for
construction of lined pond 155
(1982) and 9E (1986).
Page 4 of 4
-------
Page 1 of 2
Table!
RATIOS OF CONCENTRATIONS OF SUBSTANCES
IN PHOSPHATE ORE RELATIVE TO LOCAL
BACKGROUND SOILS
POCATELLO, IDAHO
Local
Chemical Background Soils .
Aluminum 1.00
f
t
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Calcium
Chromium
Cobalt
Copper
Fluoride
Iron
Lead
Lead-210
1
Lithium
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Orthophosphate
Phosphorus
Potassium-40
Selenium
Silver
Thallium
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1. 00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
Ore
0.89
7.64
1.90
0.56
1.90
5.80
40.95
3.06
29.89
0.11
8.25
22.00
0.62
0.42
1.65
0.73
0.09
0.25
2.25
6.98
8.13
935.14
98.07
0.53
4.49
2.68
97.04
A-27
-------
Page 2 of2
Table 2
RATIOS OF CONCENTRATIONS OF SUBSTANCES
IN PHOSPHATE ORE RELATIVE TO LOCAL
BACKGROUND SOILS
EASTERN MICHAUD FLATS
POCATELLO, IDAHO
Chemical
Uranium-238
Vanadium
Zinc
Local
Background Soils
1.00
1.00
1.00
Ore
6.24
21.94
18.77
A-28
-------
Page 1 of I
KJ
VO
Table 3
SUMMARY OF ON-SITE SURFACE SOIL ANALYTICAL RESULTS
Chemical*
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Cobalt
Copper
Fluoride
Lead
Lead-210
Lithium
Manganese
Mercury
Molybdenum
Nickel
Selenium
Silver
Jranium-238
Vanadium
Zinc
Units
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
pCi/g
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
pCi/g
mg/kg
mg/kg
Frequency
of Detection
31/31
1/30
21/21
31/31
26726
" 23/23
26/31
31/31
27/31
31/31
31/31
27/29
31/31
26/26
31/31
9/13
18/29
30/30
18/18
16/30
31/31
31/31
31/31
Minimum
Detected
Concentration
6160
7.8
2.2
8S.8
0.3
5.8
0.71
16.3
0.64
8.4
410
5.5
12
4
46.1
0.06
1.9
11.7
0.62
1.1
12
23.5
53.4
Maximum
Detected
Concentration
20400
7.8
15.8
847
2.9
1550
918
763
8.9
109
155000
157
216
36.9
557
15.6
36.3
3400
680
87.1
216
980
15200
Average
12405.81
5.68
7.82
242.03
1.10
112.45
58.27
177.09
3.98
37.08
16867.74
20.88
73.75
10.86
255.81
1.59
6.86
154.90
45.07
6.37
73.75
237.55
846.21
Background
13900
2.2
7.7
188
1
12.8
1.9
27.5
7.6
12.6
600
29.1
3.03
16.1
482
0.16
2.15
15.5
1.36
1.9
3.88
45.4
52.8
Frequency of
Exceedance of
Background
10/31
1/30
9/21
12/31
8/26
20/23
24/31
25/31
2/31
28/31
30/31
6/29
31/31
2/26
1/31
6/13
17/29
26/30
16/18
13/30
31/31
23/31
31/31
RBCfor
Worker Soil
Ingestion
2599726.00
358.58
1.43
61611.59
0.58
80636.05
448.23
896457.30
33258.56
53787.44
6.24
17929.14
4475.04
268.91
4482.29
17929.14
4482.29
4482.29
4.42
6275.20
268937.20
Frequency of
Exceedance of
RBCfor
Worker Soil
Ingestion
0/31
0/30
21/21
0/31
22/26
0/23
1/31
0/31
0/31
3/31
31/31
0/26
0/31
0/13
0/29
0/30
0/18
0/30
31/31
0/31
0/31
Lead-210 and Uranium-238 were the only radionuclides measured in on-site soil.
-------
Page 1 of 2
CO
o
Table 3A
SUMMARY OF OFF-SITE SURFACE SOIL ANALYTICAL RESULTS
Chemical
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Cobalt
Copper
Fluoride
Lead
Lead-210
Lithium
Manganese
Units
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
pCi/g
mg/kg
mg/kg
Frequency of
Detection
1427143
16/127
128/137
143/143
125/138
132/136
135/139
143/143
115/138
143/143
143/143
143/143
76/94
143/143
143/143
Minimum
Detected
Concentration
1,150
3.8
1
69.8
0.14
1.42
0.32
9.3
1.8
8.7
164
0.8
0.441
6.1
44.9
Maximum
Detected
Concentration
18,900
26.6
18.4
770
2
197
189
608
11.3
84.4
27,200
2,030
50.8
65.6
1,330
Average
12,520.21
3.97
5.39
169.03
0.77
10.86
22.08
81.85
4.75
21.52
2,469.95
42.55
6.69
13.45
428.32
Background
13,900
2.2
7.7
188
I
12.8
1.9
27.5
7.6
12.6
600
29.1
3.03
16.1
482
Frequency of
Exceed a nee
of
Background
35/143
16/127
22/137
24/143
25/138
28/136
104/139
76/143
7/138
127/143
72/143
46/143
51/89
22/143
44/143
RBC for
Residential
Soil and
Homegrown
Produce
Ingestion
221,655.20
14.92
0.35
3,365.12
0.20
115.95
6.70
69,081.38
348.77
3,759.49
500.00
0.57
1,367.48
144.34
Frequency of
Exceedance of
RBC for
Residential Soil
and Homegrown
Produce
Ingestion
0/143
3/127
128/137
0/143
123/138
1/136
62/139
0/143
,..,
0/143
22/143
1/143
69/89
0/143
138/143
-------
Page 2 of 2
Table 3A
SUMMARY OF OFF-SITE SURFACE SOIL ANALYTICAL RESULTS
Chemical
Mercury
Molybdenum
Nickel
Polonium-210
Potassium-40
Selenium
Silver
Thallium
Uranium-238
Vanadium
Zinc
Units
mg/kg
mg/kg
mg/kg
pCi/g
pCi/g
mg/kg
mg/kg
mg/kg
pCi/g
mg/kg
mg/kg
Frequency of
Detection
79/115
32/134
134/143
94/94
94/94
87/129
100/139
117/137
81/94
143/143
143/143
Minimum
Detected
Concentration
0.05
1.3
6.7
0.387
5.96
0.29
0.2
0.02
0.0111
10.6
43.7
Maximum
Detected
Concentration
1.2
19.1
124
50.9
31.4
16.3
10.8
3.9
26.9
729
1.540
Average
0.15
2.61
23.20
7.76
16.97
1.75
1.72
0.48
3.97
101.38
223.21
Background
0.16
2.15
15.5
3.58
20.5
1.36
1.9
0.27
3.88
45.4
52.8
Frequency of
Excecdance
of
Background
19/115
23/134
55/143
59/89
17/89
38/129
32/139
51/137
22/89
49/143
139/143
RBCfor
Residential
Soil and
Homegrown
Produce
Ingestion
3.05
131.29
578.30
4.88
0.07
228.64
91.51
6.16
1.08
502.82
855.16
Frequency of
Eiceedance of
RBCfor
Residential Soil
and Homegrown
Produce
Ingestion
0/115
0/134
0/143
55/89
89/89
0/129
0/139
0/137
72/89
10/143
12/143
>
-------
Table 4
LOCATIONS WHERE GROSS ALPHA ACTIVITIES WERE MEASURED
ABOVE THE SOIL SCREENING LEVEL IN SUBSURFACE SOIL
Sample
n>
S004B
S004B
S006B
S036B
S049B
SOS2B
S068B
S069B
S070B
S071B
S071B
S100B
S100B
S100B
S100B
S101B
S103B
Location
Beneath gypsum stack
Beneath gypsum stack
Beneath gypsum stack
Ammonia # I plant
Ammonium sulfate plant
Triple superphos. plant
Cooling tower area
Cooling tower area
Former cooling pond
Former cooling pond
Former cooling pond!
Former cooling pond
Former cooling pond
Former cooling pond
Former cooling pond
Cooling tower area
Former phos acid rail car
cleaning
Sample
Depth
(feet)
20
70
10
2
2
2
5
1
7
2
5
2
5
7
10
2
7
Sample Description
Pale brown silt
Pale brown silt
Dark brown silty sandy
Gravel
Tan silt with gravel
Dark brown clayey silt
With gravel
Brown silt
Silty gravel
Light gray gravel
(Backfill)
Weak red silty sand
Black silt (fill)
Light yellowish-brown sandy
Gravel
Tan silt
Fill (sandstone)
Activity
(pCi/g)
52.5
55.7
69.4
44.5
47.2
49.1 J
42.5 J
205.0 J
50.1
364.0
160.0J
178.0
155.0
60.5
90.1
72.2
156.0
A-32
-------
Page 1 of 4
TibtoB
SUMMARY OF GROUNDWATER ANALYTICAL RESULTS
Chemical
Maul*
A!umini*n
Antimony
A/Mnc
Barium
Beryllium
Bonn
Cadmium
Chromium
Cobel
Copper
Iron
lead
Lithium
Manganese
Mercury
MoryMenum
N«*el
Seleruum
Sifrtr
Thallium
Vanadium
Znc. lolal
Unltt
Frequency
d
ConcMitraUon
—
Background
mg/l
mo/1
mod
mg/1
mg/1
mg/l
rnpfl
mg/l
mg/l
mgfl
mgfl
mo/I
mg/1
mg/1
mgA
mg/1
mg/1
mgl
mo/I
mg/l
mgt
146*31
17/737
83*71 <
791/813
MW7S
83*690
104/746
386/616
K6^42
131«44
277/5*9
72/743
563/572
443/704
81/290
1I&670
102/897
406/6J6
60^65
49/711
312«32
109/450
00168
0039
0.0014
00079
0.0002
00343
0.0001
0.0003
00024
0002
001
00006
0005
0001
00001
00092
00079
00006
0002
0.0003
00021
0.0029
S87.4
1.073
SS32
2.224S
0.0033
69
39
7584
0.1369
1.1235
154.31
0.71
4.146
91.2
0.0043
OJ555
34581
19735
002
90699
22.317
28914
3.118134
0.0339533
0.1119646
0.1205218
00009S56
0.9603396
0.0224268
0.0348992
0.0090511
0.0107905
1.262207
0.002061
0.1266687
0.7798741
0.0002734
0.0122956
0.0292505
0.047591
0.0021373
00154203
0.1332993
02*44352
0591777
0.05
00162075
0.22376
0.001
0238107
0.002S
0.006628
0.006325
0.0049B7S
0.648248
0.002
0.081 3445
0.03625
0.00037
0.046
0.01
0004886
0.002
0.002
0.01
00174
Frequency of
Exc**d«nc« of
Background
47/B31
14/737
439/714
6ST813
49473
393*90
84/746
32*16
182/742
99*44
84088
42/742
311/572
345/704
35/290
17*70
99*97
224*26
43*65
13/711
137*32
70/450
Primary
HCL
0008
005
2
0.004
0.005
0.1
1.3
-
0015
0002
0.1
005
0002
Frequency
of
Exceadinee
of
Primary
MCL
17/737
258/714
2*13
5*73
23/746
5*16
O*44
•
7/742
6/290
10*97
39/626
13011
Secondary
MCL
Frequency of
Cxceedance
Secondary
MCI
RBCIor
ReeldenUal
WtterlngeaDon
Frequency of
Eiceedance of
RBCior
R«.ld«nd»l
W«Hr
IngeiUon
005
1
03
005
01
5
110/631
2/644
106/506
333/704
0/665
V450
4506706
0006199296
0000048003
1067297
0000019566
1.362344
0007775578
007661079
05539213
03103279
007661277
0004634573
007763741
0298G646
007521498
007611
0001245548
01077162
3920S42
4*3 1
17/737
639/714
3*13
63*73
87*90
15/748
5*16
-
4*44
-
-
44/572
312/704
0/290
3*70
7*97
30*26
0*65
21/711
21/632
5/450
•
-------
PtgeZoM
Tcbtol
SUMMARY OF OROUNDWATER ANALYTICAL RESULTS
Charrtcal
1.1.1-
Tricnloroalhan
•
2-flutanona
Acaun*
Carbon
d»u»io»
Craorobaraana
Chtttfem,
Effiyfbanlana
Marnylana
eftlorida
TMrKfitorowi
ano
TMuana
TficMoroathao
•
Xylaoat
Unit*
mg/l
m^l
men
rngfl
fflgfl
mgn
mg/l
m^fl
mgfl
m»«
mQfl
mpfl
Samlvolalll* Organic
Baruoie acid
8>l(2-alhyt>a»y
1)
pMh»l«l»
Oi-o-butyiphm»
l«<
t)Miooyiphm«
l«t»
DntfiyfHh»li1
•
Dm»Ihy(phchil
«•
mg/l
mg/l
mprt
mgfl
•*•
moA
Frequency
2/136
7/107
28/108
7/112
2/138
2/127
47138
2/108
12/136
8/111
14/135
8/130
Minimum
O*IKt*tf
Concentration
0008
0.003
0.028
0.001
0.001
0.001
O.001
0.001
0001
0001
0001
0001
Maximum
IMactad
Concwimtton
0.009
0.01
S.27S
0.168
0.0011
0001
0.002
0.0039
0.033
0004
0028
0.011
Avaraga
0.0026249
00099018
0.1919811
0.0047277
O.OQBS2Q2
0002*981
0.0025074
0.0027D28
0.00275
0.0024685
0.0029276
00026635
Background
0.002875
0.0025
2/125
65/83
9/112
2/134
2/122
11/12)
0001
0001
0001
0001
0.001
0001
0003
0054
0004
0002
0001
0087
0.024632
0.0083072
0.0049018
00049328
00049344
0.0079674
rraojuancy of
ExcMdancaof
Back ground
8/138
9/135
Primary
UCL
o.oos
0005
Frvquaney
of
Excaadanca
of
Primary
MCL
.
1/138
V13S
Secondary
MCL
Fraquancy of
Exeaadanca
Sacondary
MCL
HSCfor
Maatdantal
Walar Inoaadon
0001428671
0 002 V< 2289
Fraquaney of
Excaadanca of
RBCfor
Raaldandal
Walar
IngtaHon
9/138
9/135
-------
Page 3 of 4
T«bl»«
SUMMARY OF GROUNDWATER ANALYTICAL RESULTS
Chwnlcil
TW«hy<*ori*«
n
MadtonucUdn
ArtimonH25
Cnkxn-134
CotMil-57
CoCxl-60
EimoiurrM52
Eiroprum-154
Gro«««lph«
Groutwtl
Lud-210
Pok>nlum.210
Pot«lium-40
RnJium-226
R*dun-228
RlXrieniwrTt-108
Sodun-22
Triorium-226
Thorium-230
Trwrium-232
Urmium-233/2
34
Urtnum-235
Unltt
men
pCA
PCM.
fCA.
fCA
pen.
PCM.
pen.
pen.
pen.
pen.
pen.
pen.
pen.
pCrt.
pen.
pen.
pen.
pen.
pen.
pCrt.
pen.
Frvqutncy
ofDtlKtlen
1/46
MMImum
O*t«cl*d
0292
1/12
2/12
1/1J
2/12
1/12
1«2
563m4i
74V766
3/11
1/7
7/12
S93fi23
27VS20
1/12
3/12
W
W
2/7
7/7
3/7
_«"*
*
3.07
448
388
11.7
822
•723S
0.78S
47.85
•0049
32*
DOS
-01
237
25
.0035
•0009
•0019
0199
0104
7125
Mulfnum
Dtttctod
ConcMttraflon
0.292
9
39
4.48
4.21
11.7
8.22
1.890
1.355
308.3
•0049
1.330
7.09
139
23.7
334
033
0.3
-0017
2875
04105
180
Avmgo
0.008793$
3583
049*4171
09099867
1.138579
2884825
2154041
9.514483
51.34504
149.7827
0.0891143
275.4083
0640572$
1.218124
7.0882$
1.377383
0.0698288
0.1535286
00685288
8.732285
0.1337
5283454
Background
EzcMdinc* ot
Background
Pitouuy
HCL
15
50
20
20
Frvquvncy
of
ExCMdwic*
of
Primary
MCI
58/841
134/788
-
0/623
tVSJO
Secondary
MCL
Fraqutrwyet
EjICMdwKI
S«condary
MCL
RBCfer
R*«ldw
-------
Page 4 of 4
TabtoS
SUMMARY OF GROUNDWATER ANALYTICAL RESULTS
Chemical
YIMum-a8
Zrc-65
W«l«r Quality
Ammonia (NH3
UN)
Cafckm
Chtarida
FkiorUa
u*0n*^«n
N*raU>P)
Phoapfiorus.
lotll
Potusiun
Sodium
Sulfate
Unltm
pCA
pCiO.
*
man
man
man
man
mgn
myfl
man
mgl
man
man
alDMcVon
1/12
1/12
181/781
8JS/W7
C20IB21
78«905
637/837
82M79
eaiffai
709ff86
884M4
82M23
890091
Minimum
Ctaucttd
Canctnlntton
3K
4781
0.2
15.4
9
0.08
O.S
00$
0.015
0015
29
126
0.83
Maximum
CtaUctad
COOCMI brvflon
334
4.781
U20
1.211
7.7SO
2.81 S
694
660
4.760
6.830
29.010
5.206
36.400
Anno*
0.6949S63
.1.018333
3151017
140.6328
1S45J26
7.501513
61.S3564
6.605706
4398906
50.9344
99.35796
164.1313
422.047
Background
183.4
.0.8
63.15144
FtVQiMncy of
CxCMdVK**
Badiground
194A21
235/906
472/V23
Mnmy
MCt
4
Fraqmncy
of
ElCMdMK*
of
Pflnwy
MCL
4C8O5
••
Steondtrt
MCL
250
2
20
Frequency of
Ejcc«idtnc«
8*condary
MCL
122/621
69/905
805/823
RBCfor
RMManau
W«t*r1ngntlon
0.9319686
Fraqutncy of
Eie»»d>nc« of
RBCfor
Ruktantltl
W»l«f
IngosOon
168/905
K.y
MCI. * Muimuni Conuminanl L>v*l
RBC • Rftlt-taMdcancintrition.
-------
Page 1 of2
Table 6
SUMMARY OF AIR ANALYTICAL RESULTS
Chemical
Aluminum
Arsenic
Barium
Beryllium
Cadmium
Chromium
Gross alpha
Gross beta
Lead-210
Manganese
Nickel
Phosphorus
Polonium-210
Radium-226
Radium-228
Selenium
Silver
Units
Mg/m
/ig/m
>ig/m
Mg/m3
/*g/m
/ig/m
pCi/m3
pCi/m3
pCi/m3
Mg/m3
^g/m3
n&m
pCi/m3
pCi/m3
pCi/m3
/ig/m
H&m
Frequency of
Delect
143/206
234/323
148/206
11/206
135/323
144/323
12/16
15/16
328/351
203/206
35/244
130/323
343/351
49/351
72/234
27/206
21/206
Minimum
Detected
Concentration
0.01348758
0.0001552321
0.001654159
0.0001574981
0.001322299
0.0006014503
0.0009556486
0.002679193
0.0020951
0.0005923851
0.003167659
0.1804351
0.0003668404
0.00001792433
0.0001174482
0.01621767
0.001137036
Maximum
Detected
Concentration
0.7558537
0.004613158
0.02286252
0.0002707787
0.05603214
0.1021287
0.0523169
0.01173803
0.1169215
0.02644496
0.009066898
19.10782
0.3505943
0.003332056
0.01580375
0.1208713
0.004287942
Average
0.1422603
0.0006511955
0.003815881
0.0000893683
0.002797181
0.0037329
0.006434824
0.006193763
0.02316781
0.005779869
0.002123739
1.188753
0.01910664
0.0001055182
0.00103737
0.01149783
0.0006996106
Background
0.333965
0.0014533
0.004592
0.0000853
0.000683
0.000636
0.053491
0.013395
0.002563
0202894
0.015654
0.001053
0.002883
0.008532
0.000595
Frequency of
Exceedance of
Background
20/206
41/323
55/206
11/206
135/323
143/323
24/351
j 6/206
35/244
127/323
103/351
10/351
14/234
27/206
21/206
RBC for
Inhalation
0.0004146172
3.836927
0.0007453238
0.0009937652
0.0001490648
0.001190476
0.3756432
0.007453239
0.001831502
0.001587302
0.006901311
Frequency of
Exceedance
of RBC for
Inhalation
139/323
0/206
0/206
135/323
144/323
328/351
0/206
3/244
327/351
1/351
2/234
Key at end of table.
-------
Page 2 of2
Table 6
SUMMARY OF AIR ANALYTICAL RESULTS
Chemical
Thallium
Thorium-230
Thorium-232
Uranium
Vanadium
Zinc
Units
Hg/m~
pCi/m3
pCi/m3
pCi/m3
ng/m3
A<6/m3
Frequency of
Delect
6/206342
235/351
6/234
347/351
141/323
293/323
Minimum
Detected
Concentration
0.03193704
0.0000232234
0.00002112716
0.00000282146
0.001553667
0.001158892
Maiimnm
Detected
Concentration
0.04337898
0.001498582
0.00009968953
0.005288986
0.1215817
0.415641
Average
0.01717279
0.0001042818
0.00000735504
0.0002094924
0.004166464
0.02132566
Background
0.0171 1
0.000103
0.0000268
0.0000762
0.000857
0.010402
Frequency of
Esceedance of
Background
67206
95/351
5/234
181/351
141/323
170/323
RBC for
Inhalation
0.0001642036
0.000170068
0.0001984127
Frequency of
Exceedanee
of RBC for
Inhalation
48/351
0/234
88/351
I
iw
oo
Key:
RBC = Risk-based concentration.
-------
Page 1 of
Table 7
PORTNEUF RIVER DELTA SEDIMENT INVESTIGATION
SUMMARY OF STATISTICAL COMPARISON TO BACKGROUND
Element
Aluminum
Arsenic
Cadmium
Fluoride
Selenium
Zinc
Average
Concentration
(mg/kg)
Snake
5,050
3.11
0.369
247
0.622
35.2
Portneuf
8,100
2.89
0.934
345
0.812
42.9
b Portneuf
Significantly
Greater than
• Snake?'
Yes
No
Yes
Yes
No
Yes
Element/Aluminum Ratio
Snake
NA
2.30x10"*
I.TOxlO"5
7.79 x 10"2
4.55 x 10"5
3.05 xlO"3
Portneuf
NA
1.36x10"*
2.94 x 10"5
6.92 x 10"2
3.37 x 10"5
2.23 x 10"3
b Portneuf
Significantly
Greater than
Snake?*
NA
No
Yes
No
No
No
Average concentrations were compared (p <0.2). Appendix C discusses the statistical approach and tests used.
Key:
NA = Not applicable.
A-39
-------
Page 1 of 1
>
TableS
TERRESTRIAL ECOLOGICAL INVESTIGATIONS
SUMMARY OF STATISTICAL COMPARISON TO BACKGROUND FOR SOIL (rag/kg)
Habitat
Sagebrush steppe
Riparian
Chemical
Cadmium
Fluoride
Zinc
Cadmium
Fluoride
Zinc
Location
Bannock-Hills SW
Michaud Flats
Ferry Butte
Bannock Hills SW
Michaud Flats
Ferry Butte
Bannock Hills SW
Michaud Flats
Ferry Butte
Portncuf
Snake6
Portneuf
Snakeb
Portneuf
Snake
Frequency of
Detection
10/10
10/10
10/10
10/10
10/10
10/10
10/10
10/10
10/10
10/10
10/10
10/10
10/10
10/10
10/10
Minimum
Detected
Concentration
18.6
9.4
0.47
1,100
850
330
183
88.4
49.4
0.64
0.17
321
175
47.5
15.5
Maximum
Detected
Concentration
34.1
31.1
1.2
1,840
3,200
421
342
219
64.1
27.6
0.4
2,930
298
197
31.5
Average
Concentration
27.2
21.0
0.68
1,454
1,793
363
256
156
56.5
10.3
0.26
1,073
245
114
24.1
Is Impacted Area
Significantly Greater
Than Background
Area?
Yes
Yes
—
Yes
Yes
—
Yes
Yes
—
Yes
—
Yes
—
Yes
—
Average concentrations were compared (p <0.2). Appendix C discusses the statistical approach and tests used.
Background area.
-------
Page 1 of3
>
.e-
Table 9
TERRESTRIAL ECOLOGICAL INVESTIGATIONS
SUMMARY OF STATISTICAL COMPARISON TO BACKGROUND FOR VEGETATION (mg/kg)
Habitat
Sagebrush steppe
Chemical
Cadmium
Fluoride
Vegetation
Sagebrush foliage (unwashed)
Sagebrush foliage (washed)
Thickspike wheatgrass (steins
and leaves)
Sagebrush foliage (unwashed)
Sagebrush foliage (washed)
Thickspike wheatgrass (stems
and leaves
Location
Bannock Hills SW
Michaud Flats
Ferry Butteb
Bannock Hills SW
Michaud Flats
Ferry Butteb
Bannock Hills SW
Michaud Flats
Ferry Butteb
Bannock Hills SW
Michaud Flats
Ferry Butteb
Bannock Hills SW
Michaud Flats
Ferry Buttcb
Bannock Hills SW
Michaud Flats
Ferry Butteb
Frequency
of Detection
10/10
10/10
5/10
10/10
10/10
4/10
10/10
10/10
2/10
18/20
19/20
0/20
0/20
0/20
0/20
10/10
4/10
0/10
Minimum
Detected
Concentration
0.81
0.97
0.2
0.59
0.61
0.21
0.31
0.33
0.14
47.3
25.5
—
—
—
—
39.6
25.0
—
Maximum
Detected
Concentration
1.2
1.7
0.35
1.2
1.5
0.34
' 0.88
• 0.59
0.40
122
114
—
—
—
—
Ill
51.1
—
Average
Concentration
0.99
1.27
0.17
0.77
1.10
0.17
0.54
0.46
0.12
74.2
55.6
I2..d
—
—
—
62.1
22.4
12.2e
Is Impacted Area
Significantly
Greater Than
Background
Area*
Yes
Yes
—
Yes
Yes
—
Yes
Yes
—
Yesc
Yesc
—
e
e
—
Yesc
Yesc
—
-------
Page 2 of 3
Table 9
TERRESTRIAL ECOLOGICAL INVESTIGATIONS
SUMMARY OF STATISTICAL COMPARISON TO BACKGROUND FOR VEGETATION (mg/kg)
Habitat
Riparian
Chemical
Zinc
Cadmium
Vegetation
Sagebrush foliage (unwashed)
Sagebrush foliage (washed)
Thickspike wheatgrass (stems
and leaves)
Russian olive (fruit)
Location
Bannock Hills SW
Michaud Flats
Ferry Butteb
Bannock Hills SW
Michaud Flats
Ferry Butteb
Bannock Hills SW
Michaud Flats
Ferry Butteb
Portneuf
Snakeb
Frequency
of Detection
10/10
10/10
10/10
10/10
10/10
10/10
10/10
10/10
10/10
5/10
1/10
Minimum
Detected
Concentration
26.1
30.6
22.7
• 22.4
15.0
23J
6.5
7.9
5.2
0.2
0.66f
Maximum
Detected
Concentration
39.8
49.1
44.1
31.5
43.9
40.7
16.5
15.1
10.5
0.33
0.66f
Average
Concentration
31.2
38.3
30.2
26.0
32.7
27.6
11.5
10.8
8.2
0.18
0.10
Is Impacted Area
Significantly
Greater Than
Background
Area*
No
Yes
—
No
Yes
—
Yes
Yes
—
Yesc
—
-------
Page 3 of 3
Table 9
TERRESTRIAL ECOLOGICAL INVESTIGATIONS
SUMMARY OF STATISTICAL COMPARISON TO BACKGROUND FOR VEGETATION (rag/kg)
Habitat
Chemical
Fluoride
Zinc
Vegetation
Russian olive (fruit)
Russian olive (fruit)
Location
Portneuf
Snakeb
Portneuf
Snake6
Frequency
of Detection
0/10
0/10
10/10
10/10
Minimum
Detected
Concentration
—
—
7.3
5.4
Maximum
Detected
Concentration
—
—
13.3
9.4
Average
Concentration
12.0d
II. 9d
10.2
7.2
Is Impacted Area
Significantly
Greater Than
Background
Area*
e
—
Yes
—
. Average concentrations were compared (p <0.2). Appendix C discusses the statistical approach and tests used.
b
Background area.
Meaningful statistical comparison to background area not possible because all background samples were less than method detection limit. Potentially impacted area judged to be elevated because
. of high frequency of detects compared with background area.
One-half of detection limit.
f Meaningful statistical comparisons not possible; all reported values were less than method detection limit.
Outlier.
-------
Page I of 1
£-
.C-
Table 10
TERRESTRIAL ECOLOGICAL INVESTIGATIONS
SUMMARY OF STATISTICAL COMPARISON TO BACKGROUND FOR DEER MICE (mg/kg)
Chemical
Cadmium
Fluoride
Zinc
Tissue
Whole body
Whole body
Femur
Whole body
Location
Bannock Hills SW
Michaud Flats
Ferry Butteb
Bannock Hills SW
Michaud Flats
Ferry Butteb
Bannock Hills SW
Michaud Flats
Ferry Butteb
Bannock Hills SW
Michaud Flats
Ferry Buttcb
Frequency of
Detection
10/10
10/10
10/10
10/10
10/10
0/10
7/10
10/10
3/10
10/10
10/10
10/10
Minimum
Detected
Concentration
0.24
0.08
0.02
93.8
50.4
—
196
291
195
31.7
33
28.2
Maximum
Detected
Concentration
1.2
0.42
0.15
173
135
—
760
1,030
301
48.1
43.5
48.3
Average
Concentration
0.61
0.22
0.07
128
90.9
6.8d
297
633
130
38.5
37.6
38.6
Is Impacted Area
Significantly Greater
than Reference Area*
Yes
Yes
—
Yesc
Yesc
—
Yes
Yes
—
No
No
—
Table 3-3 (Cont.)
a
, Average concentrations were compared (p <0.2). Appendix C discusses the statistical approach and tests used.
Background area.
Meaningful statistical comparison to background area not possible because all background samples were less than the method detection limit. Potentially
, impacted area judged to be elevated because of high frequency of detects compared with background area.
One-half of method detection limit.
-------
Page 1 of2
Table 11
EMF SOIL SCREENING CRITERIA
Analyte
Aluminum
Antimony
Arsenic
Barium
7?~ryllium
Boron
Cadmium
Chromium
Cobalt
Copper
Fluoride
Lead
Lcad-210
Lithium
Manganese
Mercury
Molybdenum
Nickel
Polonium-210
Potassium-40
Selenium
Silver
Strontium
Thallium
Uranium
Uranium-238
Units
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
pCi/g soil
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
pCi/g soil
pCi/g soil
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
pCi/g soil
Background
13,900
2.2
7.7
188
1
12.8
1.9
27.5
7.6
12.6
600
29.1
3.03
16.1
482
0.16
2.15
15.5
3.58
20.5
1.36
1.9
NA
0.27
NA
3.88
Lower
RBC
22,165.52
1.491719
0.034565
336.5123
0.020117
11.59451
0.669825
6,908.139
a
34.87675
375.9492
a
0.057346
136.7482
14.43405
0.305078
13.12949
57.82999
0.488262
0.007029
22.86415
9.150839
413.6858
0.615519
20.94732
0.108358
Higher
RBC
221,655.2
14.91719
0.34565
3,365.123
0.201167
115.9451
6.698249
69,081.38
a
348.7675
3,759.492
400b
0.573462
1,367.482
144.3405
3.050778
131.2949
578.2999
4.882621
0.070288
228.6415
91.50838
4,136.858
6.155192
209.4732
1.083576
Key at end of table.
A-45
-------
Page 2 of 2
Table 11
EMF SOIL SCREENING CRITERIA
Analyte
Vanadium
Zinc
Units
mg/kg
rag/kg
Background
45.4
52.8
Lower
RBC
50.2819
85.51619
Higher
RBC
502.819
855.1619
. No toxicity values were available at the time data were compiled.
Residential soil screening level (EPA I994e).
Key:
NA
RBC
Not analyzed for in soil samples.
Risk-based concentration.
A-46
-------
Page 1 of2
Table 12
EMF GROUNDWATER SCREENING CRITERIA
Analyte
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Copper
Fluoride
Lithium
Manganese
Mercury
Molybdenum
Nickel
Nitrate
Radium-226
Radium-228
Selenium
Silver
Strontium
Tetrachloroethene
Thallium
Trichloroethenc
Uranium
Uranium-233/234
Units
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
pCi/L
pCi/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
pCi/L
Background
0.591777
0.05
0.0162075
0.22378
0.001
0.238107
0.0025
0.008751
0.0049975
0.8
0.0613445
0.03625
0.000965
0.048
0.01
4.636
1.552
5.32
0.0051345
0.00228
—
0.002875
0.02
0.0025
—
—
Lower RBC
4.506706
0.0006199296
4.800307E-06
0.1087297
1.958621E-06
0.1362344
0.0007775578
0.007661079
0.05539213
0.09319686
0.03103279
0.007661277
0.0004634573
0.007763741
0.02986646
2.502857
0.03931652
0.04717982
- 0.007523498
0.007611
0.8780887
0.0001428671
0.0001245546
0.0002542289
0.004645992
0.2923504
Higher RBC
45.06706
0.006199296
4.800307E-05
1.087297
1. 95862 1E-05
1.362344
0.007775578
0.07661079
0.5539213
0.9319686
0.3103279
0.07661277
0.004634573
0.07763741
0.2986646
25.02857
0.3931652
0.4717982
0.07523498
0.07611
8.780887
0.001428671
0.001245546
0.002542289
0.04645992
2.923504
Primary
MCL
—
0.006
0.05
2
0.004
—
0.005
0.1
1.3s
4
—
—
0.002
—
O.I
10
20
20
0.05
—
—
0.005
' 0.002
0.005
0.02
—
Secondary
MCL
0.05
—
—
—
—
—
—
—
1
2
—
0.05
—
—
—
—
—
—
—
0.1
—
—
—
—
—
—
Key at end of table.
A-47
-------
Page 2 of2
Table 12
EMF GROUNDWATER SCREENING CRITERIA
Analyte
Uranium-235
Uranium-238
Vanadium
Zinc
Gross alpha
Gross beta
Units
pCi/L
pCi/L
mg/L
mg/L
pCi/L
pCi/L
Background
—
0.01
0.0174
5.432
10.2
Lower RBC
0.2923504
0.1670574
0.01077162
0.3920542
—
—
Higher RBC
2.923504
1.670574
0.1077162
3.920542
—
—
Primary
MCL
—
—
—
15
b
Secondary
MCL
—
—
5
—
—
MCLG.
4 millirems/year
Key:
— = No values available.
MCL *= Maximum contaminant level.
MCLG = Maximum contaminant level goal.
RBC = Risk-based concentration.
A-48
-------
Table 13
EMF AIR SCREENING CRITERIA
Analytc
Aluminum
Arsenic
Barium
Beryllium
Cadmium
Chromium
Crystalline quartz
Crystobalite
Gaseous Fluoride
Lead-210
Manganese
Nickel
Tridymite
Phosphorus
PM,0
Polonium-210
Radium-226
Radium-228
Selenium
Silver
Thallium
Thorium-230
Thorium-232
Particle Fluoride
Uranium
Vanadium
Zinc
Units
ug/m3
ug/m3
ug/m3
ug/m3
ug/m3
ug/m3
ug/m3
ug/m3
ug/m3
pCi/m3
Mg/m3
ug/m3
ug/m3
ug/m3
(ig/m3
pCi/m3
pCi/m3
pCi/m3
ug/m3
Ug/m3
ug/m3
pCi/m3
pCi/m3
ug/m3
pCi/m3
ug/m3
Hg/m3
Background
0.333965
0.0014533
0.004592
0.0000853
0.000683
0.000636
42.0456
3.89105
0.064727
0.053491
0.013395
0.002563
7.7821
0.202894
23.9005
0.015654
0.001053
0.002883
0.008532
0.000595
0.017! 1
0.000103
0.0000268
165.625
0.0000762
0.000857
0.010402
Lower RBC
—
0.000041
0.383693
0.000075
0.000099
0.000015
_ .
_,-
0.000119
0.037564
0.000745
_
__.
_
0.000183
0.000159
0.00069
—
, —
0.000016
0.000017
—
0.00002
—
—
Higher RBC
—
0.00041
3.83693
0.00075
0.00099
0.00015
—
—
0.00119
0.37564
0.00745
—
—
—
0.00183
0.00159
0.0069
—
—
—
0.00016
0.00017
—
0.0002
—
—
NAAQS
—
—
—
_
—
—
—
—
—
—
—
—
150a.50b
—
—
—
—
—
—
—
—
—
—
—
—
, 24-hour average concentration.
D
Annual average concentration.
— = Values not available.
NAAQS = National ambient air quality standards (40 CFR. Part 50).
RDC = Risk-based concentration.
A-49
-------
Tib!* 15
TOXICITY VALUES FOR CARCINOGENIC EFFECTS
Chemical
Arsenic
Beryllium
Cadmium
Chromium (VI)
Lead
Nickel refinery dust
Teuachkxoothene
Tricriloroeinene
CAS Numbar
7440-384
744O-41-7
7440-13-9
18440-29-9
7439-92-1
7440-02 -Ord
127-18-4
79-01-6
Carcinogen
data
A
A
82
S2
81
A
82
82
__
A
C-B2
C-82
82
82
Route
Oral
Inhalation
Oral
inhaiaiion
Dial
Inhalation
Oral
Inhalation
Oral
Inhaiaiion
Oral
Inhaiaiion
Oral
Inhalaton
Oral
Inhalation
OrmlSF
(mg/hg-dav)'1
Of INHL Unit
Rl»k (ug/mT
1.75
00043
4.3
00024
00018
0012
_
_
^_
000024
0052
S8«10"7
0011
1 7 » 10"*
TargM Organ
Skn
lung
Whole bcOy
Lung
_
Lung, trache*.
broncru*
Lung
_
^
Lung
Lrvar
Blood, livw
Liver
Lung
Tumor
Typ«
__
Canoar
Groaa tumor*, all trial
oofnbtrMd
_
_
CWMT
_
Canov
^ »
-m,
^
C«n»
_
L**smta
_
-
Sp»»cl«s
Hum*n
Human, mafc
Rat/Long -Evans, mala
Human
_
HumanAvTul* mate
_. .
Human
_
__
__
Human
Mna
_
-
tipotan Route
Drrting waler
Inhalation, occupational exposure
Drrtung water
Inhalation, occupational exposure
Inhalation, occupational exposure
Inhalation, occupational exposure
_
Inhalation, occupational exposure
Oral. Gavage
Inhalation
Oral. Gavage
Inhalation
Source
IR
IR
IR
IR
IR
.
IR
_
__
IR
ECAO
ECAO
ECAO
ECAO
»_n
O
Key
ECAO = Envronmental Criteria and Atsetsmeni Office (EPA)
IR = IRIS (EPA 1994B)
SF = Slope lactor
-------
Page I of 5
T«bl« 16
TOXICITY VALUES FOR NONCARCINOGENIC EFFECTS
Chamtcal
Alum mum
Antimony
Arianic
Baryllium
Boron
Caamum
CAS Numb**
7429-90-5
7440-36-0
7440-38-2
7440-41-7
7440-42-8
7440-43-9
Rout*
Oral
Inhalation
Oral
Inhalation
Oral
Inhalation
Oral
Inhalation
Oral
Inhalation
Oral Water
Oral Food
RID Typo
Ovorac
Subchronic
Chronic
Subohrone
Chrome
Subotvonic
Chronic
Subdvomc
Chronic
Subcftror^c
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
Oral RTO
(mpAg-day) or
Inhalation RfC
(mcynO
1
_
00004
00004
_ .
^
00003
0,0003
_
_
0.005
OOOS
—
009
009
002
002
00005
00009
0001
0001
OF
100
_
__
_
1.000
1.000
^
_
3
3
__
100
100
_
_
100
100
100
100
10
_
10
—
MF
-
^_
^.
1
_
^
_
1
_
^ .
1
_
_
...
1
1
_
1
—
ConftdMKa
Laval
low
_
Low
_
Madium
_
^
Low
_
Madun
„
—
HiQh
—
High
Target Oryan
Ccntrttl n*rvous
tyttwn
_
_,-
_
inmOto body
WhotabwJy
_
Skin
SMn
—
_
Taitat
Taita>
Respratory I/act
Raipiralory trad
Kionay
Kidnay
Kidnay
Kidnay
Critical Eflact
NaurobahaviorM doficit>
_
Longavity
IncraaMd mortality
_
Hyporp<0mantation
Karalotit
—
Nonaob»arved
Nonaobtarvad
—
_
Atrophy
Lationt
Irritation
britjlion
Significant protainuf la
Significant protamuna
Significant prolamuna
Sion**icanl Protanuna
Sourca
ECAO
v
_
IR
HE
__
IR
HE
IR
HE
IR
HE
HE
HE
IR
CO
IR
CO
Data
l-Jan-95
_
_
01 FaO-91
31-M0T-94
_
_
01 -Mar 93
31-Mar 94
01-Fab-93
3t-Mar-94
Ol-Sap-94
31-Mar-94
31-Mar-94
31 -Ma, 94
OI-Fab-94
_
01- Fab- 94
Kcv ;ii cm! i>f i.i
-------
Page 2 of 5
Table 16
TOXICITY VALUES FOR NONCARCINOGENIC EFFECTS
Chemical
Chromun(lll)
Chrcxnium(VI)
Crystalline quartz*
Nuoride. Soluble
Lead
Minganaje
CAS Number
1606S-83-1
18540-29-9
14808-60-7
16984-48-6
7439-92-1
7439-96-5
Route
Inhalation
Orel
Inhalation
Oral
Inhalation
Oral
Inhalation
Orel
Inhalation
Orel
Inhalation
Oral, Water
RfDType
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
Chronic
SuDcnfonic
Chronic
Subclhroruc
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
OraJRID
(mcAB-
-------
Page 3 of 5
Ttbto 16
TOXICITY VALUES FOR NONCARCINOGENIC EFFECTS
Chemical
Mircury (Inorganic)
Nickel. Soluble
Salts
Nitrate
Phosphoric Acid*
Phosphorus
Penloxioe*
CAS Number
7439-97-6
7440-02-0
14797-55-8
7664-38-2
1314-56-3
Route
Oral, Food
Inhalation
Oral
Inhalation
Oral
lnfi«i til ion
Oral
Inhalation
Oral
inhalation
Oral
RID Type
Chronic
Subchronic
Chronic
Subchronic
Chronic
Sutocnroroc
Chronic
Suboftronic
Chronic
Subchronic
Chronic
Subehronic
Chronic
SuDcnrontc
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronic
Oral RID
-------
Page 4 of 5
Tibl« 16
TOXICITY VALUES FOR NONCARCINOGENIC EFFECTS
Ch*mleal
SaWnium
S'lvar
Tatracnkxoathan*
Thallium
Tricnloro«in*na
Uranium, johjble
»k*bo<*y
—
Crittctri Eff*cl
3*>**nosit
S*tenosis
^
—
Argyria
An»yn.i
_
__
HttpMotoiioty
ttopatotoxcity
=_
lncr*M««>d SCOT
locr«»»d SCOT
_
__
_
__
_
W»ighl toss
—
Sourc*
_
_
IR
HE
_
^
IR
HE
IR
HE
_
_
IR
HE
__
—
-
_
_
__
IR
CO
Data
_
01-Saf-91
31-Mar-»4
_
OI-Dcc-91
31 -Mar 94
_
1-Mar-M
31 -Mar. 94
_
_
Ot-Sap-90
31 -Mar. 94
_
_
01-OC1-89
_
Key at end of table.
-------
Page 5 of 5
Table 16
TOXICITY VALUES FOR NONCARCINOGENIC EFFECTS
Chemical
Vanadium
Zinc
CAS Number
7440-62-2
744046-6
Rout*
Inhalation
Oral
Inhalation
Oral
Inhalation
RfD Type
Chronic
Subchronic
Chronic
Subchronic
Chronic
Subchronie
Chronic
Subchranic
Chronic
Subchranic
OralRfD
(moAa-6ey> or
IntuuttofL RfC
(rngrm9)
_
_
0.007
0.007
—
03
0.3
-
UF
^
_
100
100
__
3
3
_,
—
MF
__
_
_
_
_
1
_
_
-
Conffdafica
Laval
«
_
_
_
—
Modun
^_
^
-
Target Organ
^
^
Whotobody
VMwtobody
— .
.^
Blood
Blood
—
-
Critical Effact
—
^
lifatim*
Lif»t»m»
_ .
^
Dacraasa (47%).
dtsntustasa
Oacraasad blood enzyma
_
-
Source
_
HE
HE
_
_ .
IR
HE
_
-
Oal«
31-M«r-94
31-Mar-94
_^
— _
01-OO-92
3l-Mar-94
_.
-
Quantilativa loxoty valua* wara raqumtad for trwM chamicali tram ECAO: howavar. ECAO ccndudad thai tha availaMa intarmation was in»ufToenl to xjpport darivation of such value*
Darivad from RfD for thallium carbonate
Key
Cl
CO
ECAO
HE
IR
MF
NA
Not available.
RtD
SCOT
SI
SO
UF
WD
Extrapolated from chronic inhalation RIC
Extrapolated from chronic oral RfD.
Environmental Criteria and Assessment Office (EPA)
HEAST (EPA 1994c)
IRIS (EPA 1994b)
Modifying factor
Reference dose.
Senm glutamic oxylate transaminase
Extrapolated from subchronic inhalation RfC.
Extrapolated from subchronic oral RfD
Uncertainty factor.
Withdrawn from IRIS or HEAST
Key al end of table.
-------
Page 1 of 1
Table 17
TOXICITY VALUES (SLOPE FACTORS) FOR RADIONUCLIDES
Radionuclide
Lead-210+D
Polonium-210
Potassium-40
Radium-226+D
Radium-228+D
Radon-222+D
Thorium-228+D
Uranium-233
Uranium-234
Uranium-235
Uranium-235+D
Uranium-238
Uranium-238+D
CASRN
014255-04-0(+D)
013981-52-7
013966-00-2
OI3982-63-3(+D)
015262-20-K+D)
014859-67-7(+D)
014274-82-9(+D)
013968-55-3
013966-29-5
015117-96-1
015117-96-H+D)
007440-61-1
007440-6t-l(+D)
SF0
(Risk/pCi)
1.01E-09
3.26E-10
1.25E-1 1
2.96E-10
2.48E-10
_
2.31E-10
4.48E-11
4.44E-11
4.52E-I1
4.70E-1I
4.27E-1I
6.20E-11
SF,
(Risk/pCi)
3.86E-09
2.14E-09
7.46E-12
2.75E-09
9.94E-IO
7.57E-12
9.68E-08
I.41E-08
I.40E-08
1.30E-08
1.30E-08
I.24E-08
1.24E-08
SFE
(RiskA'ear per
pCi/g Soil)
USE- 10
3.30E-11
6.11E-07
6.74E-06
3.28E-06
—
9.94E-07
3.52E-11
2.14E-11
2.63E-07
2.65E-07
1.50E-1I
5.25E-08
Key:
CASRN = Radionuclide CAS Number.
SFQ = Slope factor for oral exposure.
SF| = Slope factor for inhalation exposure.
SFg = Slope factor for external exposure.
Source: HEAST 1994 (EPA 1994c).
A-56
-------
TABLE 18
RADIOLOGICAL CANCER RISKS ESTIMATED IN THE BASELINE RISK ASSESSMENT
FOR CURRENT EXPOSURE PATHWAYS IN EXISTING RESIDENTIAL AREAS
Residential
Area
1
2
3
4
5
6
7
8
Exposure
Case
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
Soil Ingestion, External
Radiation Exposure and
Inhalation of Airborne
Contaminants
Estimated
L_ CR
8.78e-04
1.89e-04
5.90e-04
1.26e-04
3.146-05
6.696-06
9.376-04
2.026-04
1.426-03
3.076-04
6.026-04
1.336-04
5.596-04
1.216-04
1.226-03
2.616-04
Incremental
CR
3.726-04
7.986-05
8.476-05
1.756-05
2.966-06
6.306-07
4.32e-04
9.326-05
4.406-04
9.516-05
1.146-04
2.436-05
5.4246-05
1.186-05
Oe+00
Oe+00
CR
Ratio
1.74
1.73
1.17
1.16
1.10
1.10
1.85
1.86
1.45
1.45
1.23
1.22
1.12
1.11
0.84
0.83
Soil Ingestion, External Radiatior
Exposure, Inhalation of Airborne
Contaminants, and Consumption
of Homegrown Produce
Estimated
CR
8.786-04
1.896-04
5.906-04
1.266-04
3.146-05
6.696-06
9.376-04
2.026-04
1.426-03
3.076-04
6.026-04
1.336-04
5.606-04
1.21e-04
1.226-03
2.616-04
Incremental
CR
3.726-04
7.986-05
8.486-05
1.766-05
2.966-06
6.306-07
4.326-04
9.326-05
4.406-04
9.516-05
1.146-04
2.436-05
5.436-05
1.186-05
Oe+00
Oe+00
CR
Ratio
1.74
1.73
1.17
1.16
1.10
1.10
1.85
1.86
1.45
1.45
1.23
1.22
1.12
1.11
0.84
0.83
A-57
-------
TABLE 19
SUMMARY OF RADIOLOGICAL CARCINOGENIC HUMAN
HEALTH RISKS TO CURRENT RESIDENTS ESTIMATED IN THE BASELINE
RISK ASSESSMENT FROM THE SOIL AND VEGETATION PATHWAYS
Residential
Area
1
2
3
4
5
6
7
8
RME ICR -
Incidental
Soil
Ingestion
7.0E-06
8.2E-06
0
1.1E-05
7.96E-06
4.5E-06
6.5E-06
0
Risk Ratio'1'
5.5
6.3
—
8.0
6.1
3.9
5.1
—
RME ICR -
External
Radiation
Exposure
3.6E-04
7.18E-05
0
4.11E-04
4.22E-04
9.92E-05
3.75E-05
0
Risk Ratio'21
1.8
1.1
—
1.9
1.9
1.2
1.1
—
RME ICR -
Homegrown
Produce
Ingestion
0.00
1E-7
0.00
0.00
0.00
0.00
1E-7
0.00
(1) Background risk for incidental soil ingestion for radionudides was estimated at 1. SE-06
(2) Background risk from the BRA 4.77E-04
A-58
-------
TABLE 20
CHEMICAL CANCER RISKS ESTIMATED IN THE BASELINE RISK ASSESSMENT
FOR CURRENT EXPOSURE PATHWAYS IN EXISTING RESIDENTIAL AREAS
Residential
Area
1
2
3
4
5
6
7
8
Exposure
Case
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
Soil Ingestion and Inhalation of
Airborne Contaminants
Estimated
CR
2.25e-05
3.47e-06
9.12e-06
1.526-06
1.966-05
2.976-06
1.65e-05
1.87e-06
2.346-05
2.616-06
2.326-05
2.76e-06
1.896-05
2.50e-06
2.336-05
3.136-06
Incremental
CR
4.476-06
7.626-07
3.266-06
5.866-07
2.266-06
3.656-07
3.006-06
3.766-07
5.456-06
4.856-07
5.166-06
3.826-07
4.016-06
4.496-07
5.316-06
4.916-07
CR
Ratio
1.25
1.28
1.56
1.63
1.13
1.14
1.22
1.25
1.30
1.23
1.29
1.16
1.27
1.22
1.29
1.19
Soil Ingestion, Inhalation of
Airborne Contaminants, and
Consumption of Homegrown
Produce
Estimated
CR
9.176-05
7.866-06
1.516-05
1.906-06
8.556-05
7.156-06
5.82e-05
3.696-06
1.046-04
6.476-06
9.656-05
6.306-06
6.806-05
5.136-06
9.946-05
7.166-06
Incremental
CR
1.406-05
1.376-06
4.416-06
6.596-07
9.186-06
8.046-07
5.366-06
4.74e-07
2.606-05
1.096-06
1.896-05
6.726-07
7.516-06
5.836-07
2.176-05
8.856-07
CR
Ratio
1.18
1.21
1.41
1.53
1.12
1.13
1.10
1.15
1.33
1.20
1.24
1.12
1.12
1.13
1.28
1.14
A-59
-------
>
o
Table 21
HAZARD QUOTIENTS FOR CURRENT EXPOSURE PATHWAYS IN EXISTING EXPOSURE AREAS
Residential
Area
1
2
Location
Rowlands Dairy
Rio Vista and
Chubbock Rds.
Chemical
Arsenic
Eery Ilium
Doron
Cadmium"
Chromium(VI)
Fluoride
Manganese
Nickel
Selenium
Vanadium
Zinc
Beryllium
Boron
Cadmium*
Exposure
Case
RME
CT
RME
CT
RME
CT
RME
CT
RMI;
CT
RME
CT
RME
CT
RME
CT
RME
CT
RMI-
CT
RME
CT
RME
CT .
RME
CT
RME
CT
Soil digestion and Inhalation of
Airborne Contaminants
l^stimaied
HQ
0.06
0.03
0.00
0.00
0.00
0.00
0.07
0.04
0.01
0.01
0.19
0.09
0.01
0.00
0.00
0.00
0.00
0.00
0.04
0.02
0.00
0.00
0.00
0.00
0.00 .
0.00
o.os
0.02
Incremental
HQ
0.01
0.00
0.00
0.00
0.00
0.00
0.07
0.03
0.01
0.01
0.16
0.08
0.00
0.00
0.00
0.00
0.00
0.00
0.03
0.01
0.00
0.00
0.00
0.00
0.00
0.00
0.04
0.02
IIQ
Ratio
1.17
1.17
1.03
1.03
2.38
2.38
27.93
27.93
9.22
9.22
5.79
5.68
.00
.00
.78
.78
.96
.96
2.71
2.71
4.10
4.10
1.24
1.24
1. 00
1.00
17.56
17.56
Soil Ingcstion, Inhalation of
Airborne Conl:imin;inls, :md
Consumption of Homegrown
Produce
Estimated
HQ
0.35
0.09
0.00
0.00
0.93
0.20
1.27
0.32
0.01
0.01
0.98
0.26
0.29
0.06
0.16
0.04
0.02
0.01
0.14
0.04
0.48
0.10
0.00
0.00
0.35
0.08
0.80
0.20
Incremental
HQ
0.05
0.01
0.00
0.00
0.54
0.12
1.23
0.31
0.01
0.01
0.82
0.22
0.00
0.00
0.07
0.02
0.01
0.00
0.09
0.03
0.36
0.08
0.00
0.00
0.00
0.00
0.76
0.19
HQ
Ratio
1.17
1.17
1.03
1.03
2.38
2.38
27.93
27.93
9.22
9.22
6.13
6.01
.00
.00
.78
.78
.96
.96
2.71
2.71
4.10
4.10
1.24
1.24
1.00
1.00
17.56
17.56
Key at end of Table
I of 8
ZP3090t5-l2.»l$4/U/97
-------
>
Table 21
HAZARD QUOTIENTS FOR CURRENT EXPOSURE PATHWAYS IN EXISTING EXPOSURE AREAS
Residential
Area
3
Location
_
Trailer Court southeast
ofPhilbin Rd. and 1-86
Chemicul
Chromium(Vl)
Fluoride
Manganese
Mercury
Nickel
Silver
Thallium
Vanadium
Zinc
Arsenic
Beryllium
Boron
Cadmium*
Chromium(VI)
Exposure
Case
RME
CT
RME
CT
RME
CT
KME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
Soil Ingestion and Inhalation of
Airborne Contaminants
Estimated"
HQ
0.01
0.01
0.10
0.05
0.01
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.01
0.01
0.03
0.01
0.00
0.00
0.06
0.03
0.00
0.00
0.00
0.00
0.01
0.00
0.00
Incremental
HQ
0.01
0.01
0.06
0.03
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.01
0.01
0.00
0.00
0.01
0.00
0.00
0.00
0.00
0.00
0.01
0.00
0.00
IIQ
Ratio
9.22
9.22
2.94
2.96
.00
.00
.03
.03
.46
.46
.59
.59
.71
.71
.76
.76
3.12
3.12
.13
.13
.00
.00
.00
.00
2.90
2.90
3.21
Soil Ingestion, Inhalation of
Airborne Contaminants, and
Consumption or Homegrown
Produce
Estimated
HQ
0.01
0.01
0.46
0.12
0.28
0.06
0.22
0.05
0.13
0.03
0.08
0.02
0.02
0.01
0.09
0.03
0.36
0.08
0.34
0.09
0.00
0.00
0.29
0.06
0.13
0.03
0.00
Incremental
HQ
0.01
0.01
0.30
0.08
0.00
0.00
0.01
0.00
0.04
0.01
0.03
0.01
0.01
0.00
0.04
0.01
0.25
0.05
0.04
0.01
0.00
0.00
0.00
0.00
0.09
0.02
0.00
IIQ
Ratio
9.22
9.22
2.88
2.90
.00
.00
.03
.03
.46
.46
.59
.59
.71
.71
.76
.76
3.12
3.12
.13
.13
.00
.00
.00
.00
2.90
2.90
3.21
Key 01 end of Table
2 of 8
ZP3090l5-l2.xls 4/14/97
-------
Table 21
HAZARD QUOTIENTS FOR CURRENT EXPOSURE PATHWAYS IN EXISTING EXPOSURE AREAS
Residential
Area
4
Location
_
Southwest of Siphon
and Philbin Rds.
Chemical
Fluoride
Manganese
Mercury
Nickel
Selenium
Silver
Vanadium
Zinc
Arsenic
Beryllium
Boron
Cadmium*
Chromium(VI)
Fluoride
Exposure
Case
CT
RME
CT 1
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
HME
CT
RME
CT
RME
cr
RME
CT
RME _,
CT
RME
CT
RME
Soil Ingcslion and Inhalation of
Airborne Contaminants
Estimated
HQ
0.00
0.04
0.02
0.01
0.01
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.02
0.0 1
0.00
0.00
0.04
0.03
0.00
0.00
0.00
0.00
0.04
0.03
0.00
0.00
0.05
Incremental
HQ
0.00
0.00
A Art
U.UV
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.03
0.02
0.00
0.00
0.02
HQ
Ratio
3.21
1.11
i.ii
.24
.24
.00
.00
.16
.16
.03
.03
.49
.49
.11
.11
.48
.48
.00
.00
.49
.48
.00
.00
14.10
7.05
3.04
3.04
1.65
Soil Ingestion, Inhalation of
Airborne Contaminants, and
Consumption of Homegrown
Produce
Estimated™
HQ
0.00
6.18
0.05
0.44
0.10
0.18
0.04
0.10
0.02
0.01
0.00
0.08
0.02
0.06
0.02
0.17
0.04
0.20
0.10
0.00
0.00
0.38
0.16
0.64
0.08
0.00
0.00
0.28
Incremental
HQ
0.00
0.02
0.00
0.08
0.02
0.00
0.00
0.01
0.00
0.00
0.00
0.03
0.01
0.01
0.00
0.06
0.01
0.00
0.00
0.00
0.00
0.00
0.00
0.60
0.07
0.00
0.00
0.12
HQ
Ratio
3.21
.09
.10
.24
.24
.00
.00
.16
.16
.03
.03
.49
.49
.11
.11
.48
.48
.00
.00
.49
.48
.00
.00
14.10
7.05
3.04
3.04
1.73
Key a! end of Table
3 of 8
ZP3090lS-l2.*lj 4/14/97
-------
Table 21
HAZARD QUOTIENTS FOR CURRENT EXPOSURE PATHWAYS IN EXISTING EXPOSURE AREAS
Residential
Area
5
Location
-
East and West of Rio
Vista Rd. Between
Siphon and Tyhee Rds.
Chemical
Manganese
Mercury
Nickel
Selenium
Silver
Thallium
Vanadium
Zinc
Antimony
Arscnlt
Beryllium
Boron
Cadmium*
Chromium(VI)
Exposure
Case
CT
RME
CT
RME
CT
RME
CT
RME
cr
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
cr
RME
Soil Ingestion and Inhalation or
Airborne Contaminants
Estimated
HQ
0.06
0.01
0.02
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.01
0.01
0.03
0.03
0.00
0.00
0.14
0.07
0.07
0.09
0.00
0.00
0.00
0.00
0.01
0.01
0.00
Incremental
HQ
0.01
0.01
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.01
0.01
0.00
0.00
0.11
0.05
0.02
0.01
0.00
0.00
0.00
0.00
0.01
0.00
0.00
IIQ
Ratio
.31
.61
.28
.03
.00
.31
.16
.00
.00
.17
.00
.00
.00
.79
.31
2.58
2.08
3.97
3.97
.37
.08
.00
.00
.10
.00
3.32
2.56
3.04
Soil Ingeslion, Inhalation of
Airborne Contaminants, and
Consumption of Homegrown
Produce
Estimated
IIQ
0.16
0.57
0.30
0.22
0.09
0.12
0.07
0.01
0.00
0.06
0.03
0.01
0.01
0.09
0.06
0.30
0.16
3.31
0.74
0.41
0.25
0.00
0.00
0.43
0.16
0.15
0.03
0.00
Incremental
IIQ
0.04
0.22
0.07
0.01
0.00
0.03
0.01
0.00
0.00
001
0.00
0.00
0.00
0.04
0.01
0.18
0.08
2.48
0.55
0.11
0.02
0.00
0.00
0.04
0.00
0.11
0.02
0.00
IIQ
Ratio
.33
.61
.28
.03
.00
31
.16
.00
.00
1.17
1.00
1.00
1.00
1.79
1.31
2.58
2.08
3.97
3.97
.37
.08
.00
.00
.10
.00
3.32
2.56
3.04
Key ai end of Table
4 of 8
ZP3090 15-12 xls 4/14/97
-------
Table 21
HAZARD QUOTIENTS FOR CURRENT EXPOSURE PATHWAYS IN EXISTING EXPOSURE AREAS
Residential
Area
6
Location
'*
Between Weaver Rd.
and the Pormeuf River
Chemical
Fluoride
Manganese
Mercury
Nickel
Selenium
Silver
Thallium
Vanadium
Zinc
Antimony
Arsenic
Beryllium
Boron
Cadmium*
Exposure
Cast
CT
RME
CT
RME
CT
KMt-
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
Soil Ingestion and Inhalation or
Airborne Contaminants
Estimated
HQ
0.00
0.03
0.04
0.01
0.02
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.01
0.01
0.02
0.02
0.00
0.00
0.10
0.09
0.07
0.07
0.00
0.00
0.00
0.00
0.04
0.04
Incremental
HQ
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.07
0.06
0.01
0.00
0.00
0.00
0.00
0.00
0.04
0.04
IIQ
Ratio
3.04
.04
.00
.26
.20
.28
.07
.15
.07
.23
.15
.49
.11
.11
.00
.00
.00
66
.52
2.89
2.73
.22
.00
.38
.00
.25
.00
16.59
10.51
Soil Ingestion, Inhalation of
Airborne Contaminants, and
Consumption of Homegrown
Produce
tstimuicD
HQ
0.00
6.17
0.12
0.44
0.28
0.27
0.10
0.10
0.04
0.01
0.01
0.08
0.04
0.01
0.01
0.05
0.04
0.19
0.12
2.41
1.02
0.36
0.22
0.00
0.00
0.49
0.21
0.76
0.12
Incremental
HQ
0.00
0.01
0.00
0.09
0.05
0.06
0.01
0.01
0.00
0.00
0.00
0.03
0.00
0.00
0.00
0.00
0.00
0.08
0.04
1.57
0.64
0.06
0.00
0.00
0.00
0.10
0.00
0.71
0.11
HQ
Ratio
3.04
1.03
1. 00
1.26
1.20
1.28
1.07
1.15
1.07
1.23
1.15
1.49
1.11
1.11
1.00
1.00
1.00
1.66
1.52
2.89
2.73
.22
.00
.38
.00
.25
.00
16.59
10.51
Key al end of Table
5 Of 8
ZPJ090 15-12.*l$4/U/97
-------
Table 21
HAZARD QUOTIENTS FOR CURRENT EXPOSURE PATHWAYS IN EXISTING EXPOSURE AREAS
Residential
Area
7
Location
^
Southwest of Siphon
Rd. and Tahgee Canal
Transect
Chemical
Chromium(VI)
Fluoride
Manganese
Mercury
Nickel
Selenium
Silver
Thallium
Vanadium
Zinc
Arsenic
Beryllium
Boron
Cadmium*
Exposure
Case
RME
CT
RME
CT
RME
CT
RMC
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RMH
CT
Soil Ingestion and Inhalation or
Airborne Contaminants
Estimated
HQ
0.00
0.00
0.08
0.08
0.02
0.02
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.01
0.01
0.03
0.03
0.00
0.00
0.06
0.07
0.00
0.00
0.00
0.00
0.02
0.02
Incremental
HQ
0.00
0.00
0.05
0.03
0.01
0.01
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.01
0.01
0.00
0.00
0.01
0.00
0.00
0.00
0.00
0.00
0.02
0.02
HQ
Ratio
3.04
3.04
2.58
.80
.83
.40
.00
.00
.29
.24
.00
.00
.70
.28
.71
.48
.81
.43
3.06
2.36
1.10
1. 00
1.72
1.23
1.00
1.00
8.02
5.02
Soil Ingeslion, Inhalation of
Airborne Contaminants, and
Consumption of Homegrown
Produce
Estimated
HQ
0.00
0.00
0.45
0.23
0.65
0.33
0.18
0.11
0.12
0.07
0.01
0.00
0.09
0.04
0.02
0.01
0.09
0.07
0.36
0.18
0.33
0.19
0.00
0.00
0.30
0.13
0.37
0.06
Incremental
HQ
0.00
0.00
0.29
0.10
0.29
0.09
0.00
0.00
0.03
0.01
0.00
0.00
0.04
0.01
0.01
0.00
0.04
0.02
0.24
0.10
0.03
0.00
0.00
0.00
0.00
0.00
0.32
0.05
HQ
Ratio
3.04
3.04
2.79
1.83
1.83
.40
.00
.00
.29
.24
.00
.00
.70
.28
.71
.48
.81
.43
3.06
2.36
.10
.00
.72
.23
.00
.00
8.02
5.02
Key at end of Table
6 of 8
ZP3090 15-12 nit 4/14/97
-------
Table 21
HAZARD QUOTIENTS FOR CURRENT EXPOSURE PATHWAYS IN EXISTING EXPOSURE AREAS
Residential
Area
8
Location
Michaud Creek
Chemical
Chromium(VI)
Fluoride
Manganese
Mercury
Nickel
Selenium
Silver
Thallium
Vanadium
Zinc
Arsenic
Beryllium
Boron
Cadmium*
Exposure
Case
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
Soil Ingestion and Inhalation of
Airborne Contaminants
Estimated
HQ
0.00
0.00
0.04
0.04
0.01
0.02
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.01
0.00
0.02
0.02
0.00
0.00
0.07
. 0.08
0.00
0.00
0.00
0.00
0.02
0.02
Incremental
HQ
0.00
0.00
0.01
0.00
0.01
0.01
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.02
0.00
0.00
0.00
0.00
0.00
0.02
0.02
HQ
Ratio
3.04
3.04
.18
.00
.57
.52
.00
.00
.28
.09
.07
.00
.17
.00
.19
.00
.14
.00
.90
.69
.28
.06
.17
.16
.61
.55
7.19
5.44
Soil Ingestion, Inhalation of
Airborne Contaminants, and
Consumption of Homegrown
Produce
ETtlmateJ
HQ
0.00
0.00
0.19
0.11
0.55
0.35
0.16
0.06
0.11
0.07
0.01
0.00
0.06
0.03
0.01
0.01
0.06
0.04
0.22
0.13
0.38
0.25
0.00
0.00
0.63
0.40
0.33
0.06
Incremental
HQ
0.00
0.00
0.03
0.00
0.20
0.12
0.00
0.00
0.03
0.01
0.00
0.00
0.01
0.00
0.00
0.00
0.01
0.00
0.11
0.05
0.08
0.01
0.00
0.00
0.24
0.14 j
0.28
0.05
HQ
Ratio
3.04
3.04
.19
.00
.57
.52
.00
.00
.28
.09
.07
.00
.17
.00
.19
.00
.14
.00
.90
.69
.28
.06
.17
.16
61
.55
7.19
5.44
Key ai end of Table
7 of 8
ZPJ090l5-l2.xls 4/14/97
-------
Table 21
HAZARD QUOTIENTS FOR CURRENT EXPOSURE PATHWAYS IN EXISTING EXPOSURE AREAS
Residential
Area
Location
•
Chemical
Chromium(VI)
Fluoride
Manganese
Mercury
Nickel
Thallium
Vanadium
Zinc
Exposure
Case
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
RME
CT
Soil Ingestion and Inhalation of
Airborne Contaminants
Estimated
HQ
0.00
0.00
0.05
0.06
0.01
0.02
0.01
0.01
0.00
0.00
0.02
0.02
0.02
0.02
0.00
0.00
Incremental
HQ
0.00
0.00
0.02
0.01
0.00
0.00
0.01
0.01
0.00
0.00
0.01
0.01
0.00
0.00
0.00
0.00
HQ
Ratio
4.49
4.49
1.47
1.32
1.41
1.26
7.96
5.56
1.32
1.27
2.22
2.08
1.10
1.00
2.02
1.81
Soil Ingestion, Inhalation of
Airborne Contaminants, and
Consumption of Homegrown
Produce
Estimated
HQ
0.00
0.00
0.24
0.16
0.50
0.29
1.68
0.51
0.12
0.08
0.02
0.02
0.06
0.04
0.23
0.14
Incremental
HQ
0.00
0.00
0.08
0.04
0.14
0.06
1.47
0.42
0.03
0.02
0.01
0.01
0.01
0.00
0.12
0.06
H
-------
Page I of 1
TABLE 22
REVISED HAZARD QUOTIENTS FOR CADMIUM EXPOSURE THROUGH
COMSUMPTION OF HOMEGROWN PRODUCE
Residential
Area
1
2
3
4
5
6
7
8
Soil
Background
Location
Rowlands Dairy
Rio Vista and
Chubbock Rds.
Trailer Count SE of
Philbin Rd. and 1-86
Southwest of Siphon
and Philbin Rds.
East and West of Rio
Vista Rd. Between
Siphon and Tyhee Rds.
Between Weaver Rd.
and the Portneuf River-
Southwest of Siphon
Rd. and Taghee Canal .
Transect
Michaud Creek
EMF Study Area
Cadmium
Concentration
in Soil
(rag/kg)
20.2
12.7
2.1
5.1
10.2
1.85
2.4
7.6
12.0
2.13
3.6
3.93
5.2
0.72
Percentile
50lh
95th
50th
95th
50th
95th
50th
95th
50th
95th
50th
95th
50th
95th
50th
95th
50th
95th
Estimated
HQ
0.285
1.20
0.179
0.754
0.030
0.125
0.072
0.606
0.026
0.143
0.107
0.713
0.030
0.214
. 0.055
0.309
0.010
0.043
Incremental
HQ
0.275
1.16
0.169
0.711
0.019
0.082
0.062
0.563
0.016
0.100
0.097
0.670
0.020
0.171
0.045
0.266
0.000
0.000
A-68
-------
TABLE 23
SUMMARY OF CHEMICAL CARCINOGENIC
HUMAN HEALTH RISKS TO CURRENT RESIDENTS ESTIMATED IN THE
BASELINE RISK ASSESSMENT FOR THE INHALATION PATHWAY
Residential
Area
1
2
3
4
5
6
7
8
Air
Sampling
Station
AMS-1
AMS-1
AMS^
AMS-3
AMS-3
AMS-3
AMS-3
AMS-5
ICR(I>
2.24E-06
2.24E-06
7.22E-07
8.99E-07
8.99E-07
8.99E-07
8.99E-07
1.1E-06
Risk Ratio®
2.5
2.5
1.5
1.6
1.6
1.6
1.6
1.7
Constituents Driving Risk
Arsenic, cadmium, chromium
(VI)
Arsenic, cadmium, chromium
(VI)
Arsenic
Arsenic, cadmium
Arsenic, cadmium
Arsenic, cadmium
Arsenic, cadmium
Cadmium
(]) Based on information presented in the BRA (Table K-19)
(2) The background risk, estimated from Air Monitoring Station 6 is 1.5E-6
A-69
-------
TABLE 24
SUMMARY OF RADIOLOGICAL CARCINOGENIC
HUMAN HEALTH RISKS TO CURRENT RESIDENTS ESTIMATED IN THE
BASELINE RISK ASSESSMENT FOR THE INHALATION PATHWAY
Residential
Area
1
2
3
4
5
6
7
8
Air
Sampling
Station
AMS-1
AMS-1
AMS-4
AMS-3
AMS-3
AMS-3
AMS-3
AMS-5
ICR
3.8E-6
3.8E-6
2.8E-6
l.OE-5
l.OE-5
l.OE-5
l.OE-5
l.OE-5
Risk Ratio"
1.1
1.1
1.1
1.35
1.25
1.35
1.35
1.35
Constituents Driving Risk
Po-210
Po-210
Po-210,Pb-210
Po-210,Pb-210
Po-210,Pb-210
Po-210,Pb-210
Po-210,Pb-210
Po-210,Pb-210
(1) The background risk, estimated prom Air Monitoring Station 6 is 2.8E-5
A-70
-------
Page 1 of2
Table 25
SUMMARY OF POTENTIAL CHEMICAL CANCER RISKS FOR WORKERS AT THE FMC FACILITY'
Receptor
FMC Slag Pile
Workers
FMC Pond
Workers
FMC Maintenance
Workers
FMC Contract
Workers
Scenario
Ingestion of Soil
Inhalation of Airborne
Contaminants
Total Receptor
Ingestion of Soil
Inhalation of Airborne
Contaminants
Total Receptor
Ingestion of Soil
Inhalation of Airborne
Contaminants
Total Receptor
Ingestion of Soil
Inhalation of Airborne
Contaminants
Total Receptor
Estimated
Cancer Risk
l.02e-05
6.59e-06
1.67e-05
7.22e-06
4.06e-06
1.13e-05
6.48e-06
l.98e-06
8.46e-06
2.16c-06
6.59e-07
2.82e-06
Background
Cancer Risk
1.84e-06
6.07e-07
2.44e-06
1.23C-06
3.74C-07
1.60C-06
1.10e-06
1.82e-07
1.28e-06
3.67e-07
6.07C-08
4.28e-07
Incremental
Cancer Risk
8.32e-06
5.98e-06
1 .43e-05
5.99c-06
3.69e-06
9.68e-06
5.38e-06
1.79e-06
7.l8e-06
l.79e-06
5.98c-07
2.39e-06
EP/Bked
Ratio
5.53
10.85
6.85
5.88
10.85
7.04
5.88
10.85
6.59
5.88
10.85
6.59
•/.by
Pathway
58.19
41.81
100.00
61.91
38.09
100.00
75.00
25.00
100.00
75.00
25.00
100.00
COPCs Driving
Risk
As, Be
Cd, Cr(VI), As
As, Cd, Be
Be, As
Cd, Cr(VI), As
Be, Cd. As
Be, As
Cd, Cr(VI), As
Be, As, Cd
Be, As
Cd, Cr(VI), As
Be, As, Cd
-------
Page 2 of 2
Table 25
SUMMARY OF POTENTIAL CHEMICAL CANCER RISKS FOR WORKERS AT THE FMC FACILITY*
Receptor
Future Site Worker
Scenario
Ingestion of Soil
Ingestion of Groundwater
Inhalation of Airborne
Contaminants
Total Receptor
Estimated
Cancer Risk
l.08e-05
6.83e-04
6.59e-06
7.01e-04
Background
Cancer Risk
1.84e-06
8.26e-05
6.07e-07
8.SOC-05
Incremental
Cancer Risk
8.97e-06
6.01C-04
5.98e-06
6.16e-04
EP/Bkgd
Ratio
S.88
8.27
10.8S
8.24
% by
Pathway
1.46
97.57
0.97
100.00
COPCs Driving
Risk
Be, As
As
Cd, Cr(VI), As
As
See Table K.-5 in Appendix K for a complete summary of results.
Exposure point concentration to background concentration ratio.
-------
Page 1 of I
Table 26
SUMMARY OF POTENTIAL CHEMICAL CANCER RISKS FOR WORKERS AT THE SIMPLOT FACILITY*
Receptor
Simpiot Gypstack Worker
Simplot Maintenance Worker
Future Site Worker
Scenario
Ingestion of Soil or
Solids
Inhalation of Airborne
Contaminants
Total Receptor
Ingestion of Soil or
Solids
Inhalation of Airborne
Contaminants
Total Receptor
Ingestion of Soil or
Solids
Ingestion of
Groundwater
Inhalation of Airborne
Contaminants
Total Receptor
Estimated
Cancer Risk
1.36c-06
6.59e-06
7.94«-06
4.14«-06
1.98e-06
6.12e-06
6.906-06
1.77e-03
6.59e-06
1.78e-03
Background
Cancer Risk
1.84e-06
6.07e-07
2.44C-06
1.10e-06
1.82e-07
1.28e-06
1.84e-06
8.26e-05
6.07c-07
8.50e-05
Incremental
Cancer Rbk
0
5.98c-06
6.64c-06
3.04e-06
1.79C-06
4.83e-06
5.06C-06
1.69e-03
5.98e-06
1.70e-03
EP/Bked
Ratio5
0.74
10.85
3.25
3.76
10.85
4.76
3.76
21.42
10.85
20.96
%by
Scenario
0
100.00
100.00
62.88
37.12
100.00
0.30
99.35
0.35
100.00
COPCs Driving
Risk
As
Cd. Cr(VI), As
Cd, CrCVI), As. Be
Be, As
Cd. Cr(VI). As
Be, As. Cd
Be, As
As
Cd. Cr(VI), As
As
a See Table K-8 in Appendix K for a complete summary of results.
" Exposure point concentration to background concentration ratio.
:Zr»»_D4«*l
ZP3090.10.1
-------
Page 1 of 2
Table 27
SUMMARY OF POTENTIAL RADIOLOGICAL CANCER RISKS FOR WORKERS AT THE FMC FACILITY*
Receptor
FMC Slag Pile Workers
FMC Slag Pile Workers
FMC Slag Pile Workers
FMC Slag Pile Workers
FMC Pond Workers
FMC Pond Workers
FMC Pond Workers
FMC Pond Workers
FMC Maintenance
Workers
FMC Maintenance
Workers
FMC Maintenance
Workers
FMC Maintenance
Workers
FMC Contract Workers
FMC Contract Workers
Scenario
IngestionofSoil
Inhalation of Airborne
Contaminants
External Gamma Radiation
Exposure
Receptor Total
Ingestion of Soil
Inhalation of Airborne
Contaminants
External Gamma Radiation
Exposure
Receptor Total
IngestionofSoil
Inhalation of Airborne
Contaminants
External Gamma Radiation
Exposure
Receptor Total
Ingestion of Soil
Inhalation of Airborne
Contaminants
Estimated
Cancer Risk
1.99e-05
3.00e-05
1.05e-03
I.10e-03
1.10e-05
l.85e-05
8.97e-04
9.27e-04
9.89e-06
8.99e-06
4.03e-04
4.22e-04
3.30e-06
3.00e-06
Background
Cancer Risk
1.99c-06
9.60e-06
2.44e-04
2.56C-04
1.30c-06
5.92e-06
2.92e-04
2.99e-04
1.17e-06
2.88e-06
I.31e-04
J.35e-04
3.90e-07
9.60e-07
Incremental
Cancer Risk
1.79e-05
2.04e-05
8.09e-04
8.47e-04
9.70e-06
1.26e-05
6.05e-04
6.27e-04
8.72e-06
6.11e-06
2.72e-04
2.87c-04
2.9le-06
2.04e-06
EP/Bked
Ratio"
9.99
3.12
9.07
4.32
8.44
3.12
4.63
3.10
8.44
3.12
4.63
3.12
8.44
3.12
% by
Scenario
2.11
2.40
95.49
100.00
1.55
2.00
96.45
100.00
3.04
2.13
94.83
100.00
3.04
2.13
COPCs Driving
Risk
Pb-210, Ra-226
Po-210
ExtRad
Ext Rad
Pb-210, Ra-226
Po-210
Ext Rad
Ext Rad
Pb-210, Ra-226
Po-210
Ext Rad
Ext Rad
Pb-210, Ra-226
Po-210
Key at end of table.
-------
Page 2 of 2
Table 27
SUMMARY OF POTENTIAL RADIOLOGICAL CANCER RISKS FOR WORKERS AT THE FMC FACILITY*
Receptor
FMC Contract Workers
FMC Contract Workers
Future Site Worker
Future Site Worker
Future Site Worker
Future Site Worker
Future Site Worker
Future Site Worker
Scenario
External Gamma Radiation
Exposure
Receptor Total
Ingcstion of Groundwaler
Ingcstion of Soil
Inhalation of Airborne*
Contaminants
Inhalation of Airborne
Contaminants
External Gamma Radiation
Exposure
Receptor Total
Estimated
Cancer Risk
l.34e-04
I.41e-04
2.35e-05
1.65e-05
5.l7e-03
3.00C-05
l.41e-03
6.65e-03
Background
Cancer Risk
4.37e-05
4.51e-05
7.87e-06
1.95e-06
6.I5C-04
9.60e-06
4.60c-04
1.09e-03
Incremental
Cancer Risk
9.06c-05
9.55e-05
1.56e-05
1.45e-05
4.55e-03
2.04e-05
9.53C-04
5.56C-03
EP/Bkgd
Ratio*
4.63
3.12
14.91
8.44
8.40
3.12
4.63
6.07
% by
Scenario
94.83
100.00
0.28
0.26
81.93
0.37
17.16
100.00
COPCs Driving
Risk
ExtRad
Ext Rad
Pb-210, Ra-226
Pb-210. Ra-226
Rn-222
Po-210
Ext Rad
Rn-222. Ext Rad
-J
Ul
, See Table K-6 in Appendix K for a complete summary of results.
Exposure point concentration to background concentration ratio.
Key:
COPCs = Contaminants of potential concern.
-------
Page I of I
Table 28
SUMMARY OF POTENTIAL RADIOLOGICAL CANCER RISKS FOR WORKERS AT THE SIMPLOT FACILITY8
Receptor
Simplot Gypstack Worker
Simplot Gypstack Worker
Simplol Gypstack Worker
Simplot Gypstack Worker
Simplot Maintenance
Worker
Simplot Maintenance
Worker
Simplot Maintenance
Worker
Simplot Maintenance
Worker
Future Site Worker
Future Site Worker
Future Site Worker
Future Site Worker
Future Site Worker
Future Site Worker
Scenario
Ingestion of Soil
Inhalation of Airborne Contaminants
External Gamma Radiation Exposure
Receptor Total
Ingestion of Soil
Inhalation of Airborne Contaminants
External Gamma Radiation Exposure
Receptor Total
Ingestion of Soil
Inhalation of Airborne Contaminants
Ingestion of Ground water
Inhalation of Airborne Contaminants
External Gamma Radiation Exposure
Receptor Total
Estimated
Cancer Risk
9.256-06
3.00C-05
7.49e-04
7.88e-04
8.82c-06
8.99e-06
2.68C-04
2.85e-04
l.47c-05
4.63e-03
1.63e-04
3.00e-05
9.39e-04
5.77e-03
Background
Cancer Risk
I.95e-06
9.60e-06
2.44C-04
2.55e-04
1.17e-06
2.88e-06
1.3Ie-04
1.35e-04
1.95e-06
6.l5e-04
6.82e-06
9.60e-06
4.60e-04
l.09e-03
Incremental
Cancer Risk
7.30e-06
2.04e-05
5.05e-04
5.33e-04
7.65e-06
6.1le-06
1.36e-04
1.50e-04
1.27e-05
4.01e-03
l.57e-04
2.04c-05
4.79e-04
4.68e-03
CP/Bkgd
Ratio15
4.74
3.12
4.63
3.09
7.53
3.12
2.82
2.11
7.53
7.52
20.95
3.12
2.82
5.28
•/.by
Scenario
1.37
3.82
94.81
100.00
5.09
4.07
90.84
100.00
0.27
85.72
3.35
0.44
10.23
100.00
COPCs
Driving Risk
Pb-210, Ra-226
Fo-2iO
Exi Rad
Ext Rad
Pb-210, Ra-226
Po-210
Ext Rad
Ext Rad
Pb-210, Ra-226
Rn-222
Pb-210
Po-210
Ext Rad
Rn-222
Table 5-9 (Conl.)
. See Table K-9 in Appendix K for a complete summary of results.
Exposure point concentration to background concentration ratio.
Key:
COPCs = Contaminants of potential concern.
-------
Page I of
—i
—i
Table 29
SUMMARY OF POTENTIAL NONCARCINOGENIC EFFECTS FOR WORKERS AT THE FMC
FACILITY - CHEMICALS WITH MAXIMUM OVERALL HAZARD QUOTIENTS EXCEEDING
1'
Receptor
Future Site Worker
Future Site Worker
Chemical
Arsenic
Manganese
Scenario
Groundwater Ingestion
Groundwater Ingestion
Estimated
Hazard
Quotient
3.49
4.64
Background
Hazard
Quotient
0.39
0.01
Incremental
Hazard
Quotient
3.10
4.63
EP/Bked
Ratio*
9.02
608.19
See Table K-4 in Appendix K for a complete summary of results.
Exposure point concentration to background concentration ratio.
-------
Page 1 of
*^i
00
Table 30
SUMMARY OF POTENTIALT4ONCARCINOGENIC EFFECTS FOR WORKERS AT THE SIMPLOT FACILITY -
CHEMICALS WITH MAXIMUM OVERALL HAZARD QUOTIENTS EXCEEDING 1*
Receptor
Future Site Worker
Future Site Worker
Future Site Worker
Future Site Worker
Chemical
Arsenic
Fluoride
Manganese
Vanadium
Scenario
Groundwater Ingestion
Groundwater Ingestion
Groundwater Ingestion
Groundwater Ingestion
Estimated
Hazard
Quotient
8.95
14.51
1.32
1.28
Background
Hazard
Quotient
0.3865
0.0697
0.0076
0.0048
Incremental
Hazard Quotient
8.57
14.44
1.31
1.27
EP/Bkgd
Ratio*
23.16
208.34
172.54
264.97
See Table K-7 in Appendix K for a complete summary of results.
Exposure point concentration to background concentration ratio. I
-------
TABLE 31
Measured Air Concentrations of PM,0 and TSP
PM,o
TSP
Site
Maximu
m
Average
Minimum
Maximu
m
Average
Minimum
1
79.5
30.2
4.1
218.7
60.3
15.0
2
150.7
56.5
6.6
442.6
137.1
27.5
3
67.4
21.3
1.5
261.1
50.5
5.5
4
72.7
23.0
2.1
161.3
46.2
5.5
5
90.8
18.5
0.2
167.8
33.0
1.5
6
105.6
19.8
0.2
293.0
32.0
2.3
7
118.5
20.9
0.6
176.4
26.3
0.5
Concentrations in
A-79
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Page 1 of2
Table 33
HAZARD QUOTIENTS FOR PLANTS IN SAGEBRUSH STEPPE
AND RIPARIAN HABITATS
Measurement
Endpoint Species
Cheimical
Location
EE
(nig/kg)
TRV
(mg/kg)
HQ
Sagebrush Steppe Habitat
Sagebrush (washed)
Sagebrush (unwashed)
Thickspike wheatgrass
Cadmium
Fluoride
Zinc
Cadmium
Fluoride
Zinc
Cadmium
Fluoride
Ferry Butte*
Michaud Flats
Bannock Hills SW
Ferry Butte*
Michaud Flats
Bannock Hills SW
Ferry Buttc*
Michaud Flats
Bannock Hills SW
Ferry Buttc*
Michaud Flats
Bannock Hills SW
Ferry Buttc*
Michaud Flats
Bannock Hills SW
Ferry Butte*
Michaud Flats
Bannock Hills SW
Ferry Butte8
Michaud Flats
Bannock Hills SW
Ferry Buttea
Michaud Flats
Bannock Hills SW
0.34
1.24
0.86
NA
NA
NA
28
37.8
28
0.35
1.42
1.06
12.1
60.8
85.7
33.9
41.4
33.6
0.27
0.51
0.65
12.2
38.1
86.9
5
5
5
50
50
50
150
150
150
5
5
5
50
50
50
150
ISO
150
5
5
5
50
50
50
0.07
0.25
0.17
NA
NA
NA
0.19
0.25
0.19
0.07
0.28
0.21
0.24
1*22
" i.ti
0.23
0.28
0.22
0.05
0.10
0.13
0.24
0.76
1.74
Key at end of table.
A-80
-------
Page 2 of2
Table 33
HAZARD QUOTIENTS FOR PLANTS IN SAGEBRUSH STEPPE
AND RIPARIAN HABITATS
Measurement
Endpoint Species
Chemical
Zinc
Location
Ferry Butte1
Michaud Flats
Bannock Hills SW
EE
(mg/kg)
9.05
12.5
13.4
TRV
(mg/kg)
150
150
150
HQ
0.06
0.08
0.09
Riparian Habitat
Russian olive
Cadmium
Fluoride
Zinc
Snake River*
Portneuf River
Snake River*
Portneuf River
Snake River"
Portneuf River
O.I
0.25
11.9
12.0
8
11.3
5
5
50
50
150
ISO
0.02
0.05
0.24
0.24
0.05
0.08
Background location.
Key:
EE = Estimated exposure.
HQ = Hazard quotient.
TRV = Toxicity reference value.
•= HQ>I. potential risk identified.
A-81
-------
Page 1 of2
Table 34
HAZARD QUOTIENTS FOR MAMMALS IN SAGEBRUSH STEPPE HABITAT
Measurement
Endpoint
Species
Coyote
Deer mouse
Mule deer
Chemical
Cadmium
Fluoride
Zinc
Cadmium
Fluoride
Zinc
Cadmium
Fluoride
Zinc
Location
Ferry Butte*
Michaud Flats
Bannock Hills SW
Ferry Butte*
Michaud Flats
Bannock Hills SW
Ferry Butte8
Michaud Flats
Bannock Hills SW
Ferry Butte*
Michaud Flats
Bannock Hills SW
Ferry Butte"
Michaud Flats
Bannock Hills SW
Fciry Butte*
Michaud Flats
Bannock HillS SW
Ferry Butte*
Michaud Flats
Bannock Hills SW
Ferry Butte
Michaud Flats
Bannock Hills SW
Ferry Buttc"
Michaud Flats
EEWffl/
(mg/kg/d)
0.01
0.035
0.06
0.625
6.6
7.61
1.89
1.89
2.04
0.051
0.203
0.223
3.3
14.5
19.7
2.6
3.73
3.9
0.0045
0.022
0.02
0.255*
1.28
1.52
0.372
0.488
TRY
(mg/kg/d)
0.16
0.16
0.16
5.38
5.38
5.38
48
48
48
1.42
1.42
1.42
46.3
46.3
46.3
408
408
408
0.09
0.09
0.09
2.94
2.94
2.94
25.6
25.6
HQw/fl/
0.06
0.22
0.38
0.12
" t.2^
" 1,'4t '
0.04
0.04
0.04
0.04
0.14
0.16
0.07
0.31
0.43
0.01
0.01
0.01
0.05
0.24
0.22
0.09
0.44
0.52
0.01
0.02
Diet %
—
—
—
—
71.1%
81.9%
—
—
—
—
—
—
—
—
—
—
—
—
_
—
—
__
—
—
—
—
Soil %
—
—
—
—
28.9%
18.1%
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Key at end of table.
A-82
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Page 2 of2
Table 34
HAZARD QUOTIENTS FOR MAMMALS IN SAGEBRUSH STEPPE HABITAT
Measurement
Endpoint
Species
Chemical
Location
(mg/kf/d)
TRY
(mg/kg/d)
Diet %
Soil V.
Bannock Hills SW
0.441
25.6
0.02
Background location.
Key:
EElotai = Estimated exposure.
HQWto/ = Hazard quotient
TRY = Toxicity reference value.
— = Not calculated.
M = HQ>1, potential risk identified.
A-83
-------
Page 1 of 2
Table 35
HAZARD QUOTIENTS FOR BIRDS IN SAGEBRUSH STEPPE
AND RIPARIAN HABITATS
Measurement
Endpoint
Species
Chemical
Location
EEfofa/
(me/kg/d)
TRY
(mg/kg/d)
HQ/o/fl/
Diet %
Soil %
Sagebrush Steppe Habitat -
Homed lark
Red-tailed hawk
Sage grouse
Cadmium
Fluoride
Zinc
Cadmium
Fluoride
Zinc
Cadmium
Fluoride
Ferry Butte
Michaud Flats
Bannock Hills SW
Ferry Butte8
Michaud Flats
Bannock Hills SW
Ferry Butte8
Michaud Flats
Bannock Hills SW
Ferry Butte8
Michaud Flats
Bannock Hills SW
Ferry Butte8
Michaud Flats
Bannock Hills SW
Ferry Butte8
Michaud -Flats •
Bannock Hills SW
Ferry Butte8
Michaud Flats
Bannock Hills SW
Ferry Butte8
Michaud Flats
Bannock Hills SW
0.069
0.247
0.303
4.8
19.9
28.7
2.47
3.91
4.61
0.013
0.045
0.078
0.819
8.64
9.97
2.48
2.47
2.67
0.017
0.148
0.1 56
1.9
10.8
9.72
4.84
4.84
4.84
14.9
14.9
14.9
100
100
100
1.49
1.49
1.49
4.37
4.37
4.37
30.9
30.9
30.9
1.13
1.13
1.13
3.28
3.28
3.28
0.01
0.05
0.06
0.32
, ;' lifc
^ tm
0.02
0.04.
0.05
0.01
0.03
0.05
0.19
W
2.1*
0.08
0.08
0.09
0.02
0.13
0.14
0.58
3,29
2M
—
—
—
—
46.3%
73.2%
—
—
—
—
—
—
—
71.1%
81.8%
—
—
—
—
—
—
21.6%
37.7%
—
—
—
—
53.7%
26.8%
—
—
—
—
—
—
—
28.9%
18.2%
—
—
—
—
—
78.4%
62.3%
Key at end of table.
A-84
-------
Page 2 of2
Table 35
HAZARD QUOTIENTS FOR BIRDS IN SAGEBRUSH STEPPE
AND RIPARIAN HABITATS
Measurement
Endpoint
Species
Chemical
Zinc
Location
Ferry Butte*
Michaud Flats
Bannock Hills SW
^"total
(mg/kg/d)
1.39
2.14
2.29
TRV
(mg/kg/d)
23.4
23.4
23.4
HQto/a/
0.06
0.09
0.10
Diet %
—
—
—
Soil %
—
—
_
Riparian Habitat
Cedar waxwing
Cadmium
Fluoride
Zinc
Snake River*
Portneuf River
Snake River*
Portneuf River
Snake River*
Portneuf River
0.025
0.131
4.08
11.69
2.02
3.37
4.79
4.79
13.9
13.9
99
99
0.01
0.03
0.29
0.84
0.02
0.03
—
—
—
—
—
—
—
—
—
—
—
—
Background location.
Key:
TRV
Estimated exposure.
Hazard quotient.
Toxicity reference value.
Not calculated.
HQ> I, potential risk identified.
A-85
-------
TABLE 37
EMF SITE ECOLOGICAL RISK BASED AND MAXIMUM
CONCENTRATION OF CONTAMINANTS OF CONCERN AT
SPRINGS
Substance of
Concern
Mercury (total)
Selenium (total)
Silver
Vanadium
Units
mg/1
mg/1
mg/1
mg/1
Maximum Detected
Concentration
.0004
.01
.004
.09
EPA Freshwater
Chronic Criteria*
.000012
.005
.00012
.033"
Key:
1 From U.S. EPA 1986,1994. Hardness dependent water quality criteria calculated on a water
hardness of 240.RBCs for groundwater based on drinking water and watering homegrown
produce. RBC value based on cancer risk of 10"6 or HQ=1.
b Derived Freshwater Chronic Criteria - See Risk Assessment
A-86
-------
APPENDIX B
RESPONSIVENESS SUMMARY
RECORD OF DECISION
FOR
FINAL. REMEDIAL ACTION
EASTERN MICHAUD FLATS SUPERFUND SITE
POCATELLO, IDAHO
B-l
-------
Eastern Michaud Flats Superfund Site: Response to Public Comments
U.S. Environmental Protection Agency (EPA) response to comments received during the 75-
day public comment period (April 21, 1997 to July 10, 1997) on the Proposed Plan for
remediation of the site.
Table of Contents
Eastern Michaud Flats Superfund Site: Response to Public Comments B-l
1. Overview B-l
2. Background on Community Involvement B-2
3. Summary of Comments Received and Agency Responses B-4
Part I - Summary of Community Concerns B-4
Part II - In-Depth Response to Specific Comments B-8
Specific Comments from the Shoshone Bannock Tribes B-18
4. Attachments
Shoshone Bannock Tribes Comments on EPA Proposed Plan/ROD
Qualitative Assessment of the Effect of Recent Air Monitoring Results on the
findings of the Human Health Risk Assessment
1. Overview
The purpose of this responsiveness summary is to summarize and respond to public comments
submitted on the Proposed Plan for the cleanup of the Eastern Michaud Flats Superfund Site.
The public comment period was held from April 21, 1997 to July 10, 1997. This responsiveness
summary meets the requirements of Section 117 of the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 (CERCLA) as amended by the Superfund
Amendments and Reauthorizatiori Act of 1986 (SARA).
In the Proposed Plan, issued April121, 1997, the EPA described alternatives to address
contaminants in soil and groundwater at the EMF site. These alternatives were based on
information collected during a Remedial Investigation and Feasibility Study (RI/FS). The
purpose of an RI/FS is to conduct a thorough study of the site and to assess potential
alternatives for the cleanup of the site. The RI/FS and Proposed Plan were publicly available at
the Idaho State University Library, and copies of a fact sheet were mailed to a list of interested
local citizens developed as part of the EMF Community Relations Plan.
B-X
-------
EPA held two public meetings on May 13 and May 14, 1997 to present the results of the RI/FS
and outline EPA's proposed cleanup plan. The meetings were held in the Pocatello City
Council Chambers, and the Tribal Council Chambers on the Fort Hall Indian Reservation.
Approximately 75 people attended these meetings, including representatives of FMC and
Simplot. Questions asked and answered at the public meetings are recorded in the meeting
transcripts which are available in the Administrative Record for the site at the EPA Records
Center.
A number of oral comments were received during the public meetings, and eight comment
letters were received during the comment period. Members of the community were primarily
concerned about the absence of any specific actions on air emissions from the FMC and
Simplot plants.
2. Background on Community Involvement
EPA developed a Community Relations Plan (CRP) for the Eastern Michaud Flats site in 1991.
The CRP was designed to promote public awareness of activities and investigations at the site
and to promote involvement in the decision-making process. The CRP summarizes the initial
concerns of local citizens, interest groups, industries, and local government representatives.
EPA mailed several fact sheets during the course of the RI/FS and communicated with the local
media in an effort to keep the public informed about the progress of the work at the site. The
following is a summary of the major activities:
June6,1997 Fact sheet: Public Comment Period Extension
May 13 & 14, 1997 Public Hearings conducted in Pocatello and Fort Hall, Idaho
April 21,1997 EMF Proposed Plan Fact Sheet
March 5, 1997 Idaho State Journal Article on Proposed Plan
Sept 10, 1995 Idaho State Journal Article on Risk Assessment Findings
August 16,1995 Idaho State Journal Article on Air Monitoring Findings
October 28. 1993 Fact Sheet on Pond Closure at FMC
September 29, 1993 Fact Sheet on first round of sampling results
March 9. 1993 Remedial Investigation Update
April 15. 1992 Remedial Investigation Update/Ground Water Monitoring Program
December 23. 1991 Current Site Activities/Description of Community Concerns
December 20, 1991 Community Relations Plan
September 1991 Introduction to Superfund Process Fact Sheet
January 23, 1991 Congressional Update: Special Notice Letters Sent to Potentially
Responsible Parties
The RI/FS was released to the public with the proposed plan in April 1997. A fact sheet
describing the Proposed Plan and cleanup alternatives was sent to individuals on the EPA EMF
mail list. All of the documents mentioned above, as well as previous reports from earlier
investigations, were made available to the public in the Administrative Record located at the
B-3
-------
locations listed below:
Idaho State University Library
Government Documents Department
9th and Terry
Pocatello, Idaho 83209
U.S. Environmental Protection Agency
Region 10
Park Place Building
1200 Sixth Avenue, 7th Floor Records Center
Seattle, Washington 98101
EPA published a notice of the availability of these documents on April 21, 1997 in the Idaho
State Journal and the Shoshone-Bannock News. EPA met with representatives of the
Shoshone Bannock Tribes Business Council on January 14, 1997, and the Idaho Department of
Environmental Quality on January 13,1997, to discuss EPA's Draft Proposed Plan for cleanup
and to answer questions. Between February and May 1997 various articles appeared in the
Idaho State Journal regarding the proposed clean up. The public comment period on the
Proposed Plan was held from April 21,1997 to July 10,1997. EPA held public meetings May
13-14, 1997 in Pocatello and the Fort Hall Reservation. At these meetings, representatives of
EPA, FMC, and Simplot gave presentations on the findings of the Rl and risk assessment and
proposed plan, and then answered questions about the proposed cleanup and remedial
alternatives under consideration. This Responsiveness Summary, which is Appendix B of the
ROD, contains EPA's responses to the written and oral comments that were received during the
comment period.
3. Summary of Comments Received and Agency Responses
Part I - Summary of Community Concerns
General Comment: The greatest number of comments related to concerns about air quality in
the vicinity of the plants. In general, most individuals believe that ongoing air emissions
represent the greatest threat to public health, and that these emissions should be controlled
through the EPA Superfund Record of Decision (ROD).
Response: EPA shares the community concerns regarding the ongoing air emissions from the
FMC plant, most especially the emissions of particulate matter, (called PM-10 based on the size
of particles) Because these emissions continue to periodically exceed National health-based
standards, EPA is addressing these concerns under the Clean Air Act (CAA). The following
provides a detailed explanation of what EPA is doing to address these concerns and why
Superfund is not the legal tool to achieve the necessary particulate emission controls.
B-4
-------
What EPA is doing to address concerns with air quality in Pocatello
Control of the air emissions from the FMC Pocatello plant is a top priority for EPA. In
recognition of this priority the EPA Regional Administrator has designated a senior manager,
Jim McCormick, to serve as a single point of contact for coordinating technical, legal, and policy
issues among the EPA regulatory programs. FMC. and the Shoshone Bannock Tribes. EPA is
also working to produce a CAA Federal Implementation Plan (FIP), as explained in the next
paragraph, to address this problem in the manner dictated by law.
EPA created National Ambient Air Quality Standards (NAAQS) as authorized under Section 109
of the Clean Air Act (CAA), for the air pollutants, including PM-10, listed in Section 107 of the
CAA. The NAAQs are based on the latest scientific health information and are designed to
protect public health for both cancer and noncancer risks with an ample margin of safety.
Section 107 mandates that States have the primary responsibility for PM-10 emissions and
must discharge that responsibility by specifying through State Implementation Plans (SIP) how
NAAQS will be attained and maintained. Portions of Power and Bannock Counties, including
certain portions within the Fort Hall Indian Reservation, violate the NAAQS for PM-10.
Consequently, this area is designated as a nonattainment area. FMC is a PM-10 source within
this nonattainment area, but is not subject to Idaho's SIP because FMC is on Shoshone
Bannock tribal land. The Tribes have not yet undertaken development of a Tribal
Implementation Plan (TIP), therefore it is EPA's responsibility to develop a FIP for that portion
of the PM-10 nonattainment area within the Fort Hall Reservation.
EPA's Air Program anticipates publishing a notice of proposed rulemaking during 1998. Public
meetings and workshops will be scheduled to discuss the contents of the FIP control strategy.
At the time of proposal, the public will be provided a 60-day review and comment period. Final
rules for the FIP will occur after EPA has responded to the public comments. EPA fully
anticipates that control requirements for FMC in the FIP will help the area to attain the NAAQS.
While full implementation of all control technologies at the FMC Plant may take up to four years
after final rules are set, EPA expects to see emission reductions and improvements in air
quality within six months of finalizing the rule. '
In addition to controls for PM-10 and criteria air pollutants, FMC has been identified as a source
of certain hazardous air pollutants (HAPs) listed in Section 112 of the Clean Air Act and will be
subject to Maximum Achievable Control Technology (MACT) rules no later than November 15,
2000. Unlike criteria air pollutants like PM-10, Section 112 HAP rules are effective immediately
upon the promulgation of an EPA rule linking specific HAPs to specific types of facilities. These
rules are therefore not subject to control plans by a state, tribe or the federal government. A
specific rulemaking linking type of facility with specific HAPs is required because Congress
listed 188 different HAPs in Section 112. As written. Section 112 requires EPA to examine
industrial processes and require compliance with those HAPs the facility actually generates
based on its function.
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Limits on Suoerfund as a tool to regulate FMC's Ongoing Operations
The Superfund program is unique in that it provides for the cleanup of past hazardous waste
releases and of hazardous waste requiring emergency response. Congressional enactment of
the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) was
the solution to the gap in Federal environmental authority and it is intended to augment other
Federal and State authorities. If a facility is subject to state or federal rules for an ongoing
release then the Superfund program will defer control of that release to the appropriate
authority.
Background on Superfund analysis of air emissions and risks
Once an area is identified as a Superfund site an investigation called the remedial investigation
feasibility study (RI/FS) is conducted to characterize the nature and extent of site risks,
develop and evaluate cleanup options, and gather other information necessary to select a
remedy that is appropriate for a site. A baseline risk assessment is performed as part of the
RI/FS to evaluate the potential threats to human health and the environment in the absence of
any remedial action. EPA uses the results of the RI/FS and baseline risk assessment to make
a series of site-specific risk management decisions in the Superfund remedy selection process.
At the Eastern Michaud Flats site during the scoping and conduct of the RI/FS it was apparent
that air emissions (both current and the impacts of historical emissions) should be an important
part of the site investigation. However, this investigation was complicated by the fact that past
releases (on which Superfund is focussed) and ongoing emissions (the responsibility of other
federal and state regulatory programs) associated with two operating facilities (FMC and
Simplot) both contribute to overall site contamination and risk. Therefore, the initial goals of the
RI/FS, with respect to the air pathway, were designed to answer the following questions:
• Are there any significant human health or ecological risks associated with air emissions
from sources that potentially could be subject to Superfund cleanup?
• What areas at the site have been affected by historical deposition of airborne
contaminants?
• What are the sources of all current emissions at the plants?
• Which sources of air emissions are potentially subject to a cleanup under Superfund?
(Typically fugitive dusts from sources such as waste piles and abandoned or closed
areas of the site would be subject to a cleanup under Superfund.)
• Which sources of current air emissions are subject to control under the authority of the
Clean Air Act? (Ongoing emissions from stacks, buildings, and general operating areas
are subject to control under the Clean Air Act.)
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In order to help answer these questions the following activities were conducted during the Rl:
1. Development of an air modeling program to evaluate off-plant transport of plant-derived
contaminants with the goal of determining areas where deposition and impacts (both historical
and current) on the soil and vegetation were likely to be the greatest.
2. Implementation of a soil sampling program to provide information on deposition patterns and
the nature and extent of contaminants in soils surrounding the site.
3. Implementation of an air monitoring program with the following goals: a) assess ambient air
concentration data from both plant and nonplant sources near the site, b) provide data to
determine the accuracy of the air model, c) estimate risks associated with exposure to air
contaminants from all sources. This program included collection of chemical specific data (i.e.,
the chemicals associated with the particles and gases such as arsenic, cadmium, and fluoride)
as well as information on the particle sizes.
As part of the air monitoring program ambient air quality samples were collected at
seven sites (see figure 22 of the ROD), between October 2,1993 and October 31,1994.
Sites 1,2, and 7 were located within or near the boundaries of the FMC and Simplot
plants. Sites 3.4, and 5 were referred to as "community sites' in the Rl and were
located farther from the plant boundaries. Site 6, identified as the background location,
was located approximately 12 miles (20 km) west-southwest of the facilities in the
prevailing upwind direction. In addition to air quality monitoring, meteorological
observations were also collected at Site 1 near the Simplot Plant, at Site 7 in the
elevated terrain southeast of the Simplot Plant, and at the Pocatello Airport.
4. Development of an emissions inventory to help identify all sources of airborne contaminants
from the site (i.e., stack emissions, fugitive dusts from roads, ore piles, ponds etc.).
Originally EPA had intended to use the air modeling information to estimate exposures from those
sources potentially subject to Superfund cleanup. However, the Companies relied heavily on
generic source characterization data in their model, rather than site specific data, and ultimately
there was not good agreement between the modeling and monitoring results. With the potential
unreliability of the air model results EPA chose to use the air monitoring data in the baseline risk
assessment to estimate exposures to site contaminants. The downside of this approach is that the
estimated risks included exposure to all airborne contaminants, including those from sources
potentially subject to control under the Clean Air Act. It was not possible to separate out only those
sources of emissions that could be potentially subject to Superfund cleanup. However, it was
possible to draw the following conclusions from the air monitoring data that were useful in
developing a cleanup plan for the site:
• Historical deposition of airborne contaminants has occurred in the plant and off-plant areas.
The levels of contamination do not warrant a soil cleanup but do call for institutional controls
to prevent exposure to radionuclides and cadmium already present in soil. Since
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contaminants will remain in place under this remedy a five-year review will be required in
order to determine if the remedy remains effective and is protective of human health and
the environment.
• The calculated inhalation risks from all air sources were highest at station 2. Based on a
conservative residential scenario the excess cancer risks from all sources were less than
a 1 in 10,000 at this location. The risks associated with air emissions from those areas
potentially subject to a Superfund cleanup would be some portion of this total air risk. As
a general policy in order to operate a consistent Superfund program, EPA generally uses
the result of the baseline risk assessment to establish the basis for taking a remedial action.
For sites where the cumulative site risk to an individual based on reasonable maximum
exposure to historical releases for both current and future land use is less than 1 in 10,000,
a cleanup is generally not warranted. While there is uncertainty associated with the air data
and risk calculations, EPA does not believe additional information would substantially affect
the risks associated with the sources which are potentially subject to Superfund action.
General Comment: A number of comments were received on the groundwater extraction
alternative at the FMC plant. Most: individuals stated that this action was not necessary given the
already low levels of contamination at the northern edge of the company owned properties. Other
individuals expressed concerns about extraction of water and then discharge, possibly without
treatment, directly into the Portneuf River.
Response: EPA has considered these comments and reevaluated the groundwater monitoring
data and selected a "contingent" groundwater extraction system for the FMC Plant. Implementation
of the groundwater extraction and treatment system will be required if groundwater contaminants
exceed risk-based values at a specified point(s) of compliance.
Part II - In-Depth Response to Specific Comments
1. Comment: Why aren't actions being proposed under Superfund to address the community
concerns about air quality near the site? »
Response: As stated above, Superfund is not the legislative tool to address the ongoing emissions
from an operating facility. In addition, the Remedial Investigation evaluated air data in a baseline
human health risk assessment. This assessment utilized conservative (i.e., protective), yet
reasonable exposure assumption and scenarios to predict the likelihood of human health and
environmental impacts related to the air pathway. The highest estimated incremental carcinogenic
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risks' to nearby residents from all air contaminants was at station 2 (adjacent to FMC fence line)2.
Estimated risks at this location ranged from 1.5 in 100,000 to 6.0 in 100,000 from all air sources.
Risks associated with sources potentially subject to a Superfund cleanup are expected to be a
portion of these total risks. Under Superfund law action to reduce carcinogenic risk is generally
warranted when risks exceed 1 in 10,000. Therefore, since the estimated site risks are less than
1 in 10,000 and because the Superfund-regulated source contribution to the risks is expected to
be less than the risk from all sources, EPA is not proposing any specific actions under Superfund
to reduce ongoing air emissions from those areas subject to Superfund. However, ongoing air
emissions from operating facilities are subject to regulation under the Clean Air Act. EPA's air
program is currently drafting regulatory limits for particulate emissions from the FMC facility
because of its location on tribal land. Simplot, located on state land, is permitted for its air
emissions by the State of Idaho.
2. Comment Recent air monitoring results indicate that emission levels near the plants are higher
than that measured during the Superfund investigations. What could be some of the reasons for
these differences and if these results were used in the risk assessment would it change the overall
findings?
Response: During the Superfund Rl information on airborne chemicals and gases was collected
during 1993-94 and then used in the risk assessment. Risks were calculated based on the actual
concentration of chemical and radionudides measured in airborne particulate matter smaller than
10 microns in size (PM10). Subsequent air monitoring studies conducted by EPA's air program and
the Shoshone Bannock Tribes since 1996 provide information on the total mass of airborne PM10,
but not the chemical or radiological composition of these particles. For this reason it is not
possible to calculate quantitative risk estimated directly from this recent data in the same way the
original risk estimates were obtained. However, the potential risks associated with the higher
levels of particulate matter can be approximated by scaling the risk estimates using the total PM10
concentrations measured during the two periods if the composition of the particles during those
periods is assumed to be the same (see attached qualitative assessment).
The results of this comparison show that the average PM,0 concentration measured at Station 2
from October 1993 through September 1994 was 55.75 ug/m3. while that measured at the Primary
EPA station from October 1996 through May 1997 was 77.5 ug/m3, approximately a 39% increase.
If the 1996-97 risks from airborne particulate matter are approximated, as discussed above, by
simply scaling the 1993-94 risk estimates using the average PM10 concentrations measured during
these periods, the estimated 1996-97 risks at the Primary EPA monitoring station would be 39%
higher than the 1993-94 risks at Station 2. In order to estimate the approximate 1996-97 risks for
' With the exception of fluoride no non-carcinogenic risks were found to be associated with air
emissions.
: This location is owned by FMC and deed restrictions will be placed on the property to prohibit
any future residential use.
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these groups, the 1993-94 "Estimated Cancer Risks" should be multiplied by 1.39. A brief review
of the 1993-94 risk estimate indicates that all of the estimates for site workers and hypothetical
future residents fell in a range generally considered acceptable by EPA's Superfund program and
that none of the Incremental (i.e., site related) risk estimates would increase to values that would
generally indicate a need for remedial measures as a result of the higher airborne paniculate
concentrations observed during the 1996-97 air monitoring program. This finding relates only to
risks from specific airborne chemical and radiological contaminants, not to the total PM10 levels
measured, which exceeded applicable standards on a number of occasions.
There are a number of possible reasons why the 1993-94 data differs from the 1996-97 data.
Some of these factors include the following:
1. The location of Station 2 in 1993-94 and EPA's Primary monitoring station in 1996-97 were
dose to one another but were not exactly the same. As the differences between the results
obtained at the Primary EPA station and the Sho-Ban station illustrate, small differences
in monitoring locations, especially when they are close to an array of point and small area
sources like at the EMF site, can lead to noticeable differences in the observations
obtained.
2. A fourth furnace was operating at the FMC facility during most of the 1996-97 monitoring
period that was not operating for much of the 1993-94 period. This could result not only in
an increase in the total emissions during the latter period, but also in emissions coming
from different point sources (i.e., the furnace flare and pressure relief valve for the fourth
furnace) that were not active during much of the 1993*94 monitoring period. The difference
in the locations of these additional sources relative to the monitoring locations could have
contributed to the differences in the results obtained.
3. Two different air samplers, manufactured by different firms, are approved by EPA for use
in measuring airborne paniculate matter concentrations. Results obtained using either
sampler are considered acceptable and equivalent by EPA for regulatory purposes,
however most air monitoring practitioners recognize that the Anderson Sampler typically
gives results slightly higher than those given by the Wedding Sampler. Wedding Samplers
were used in the 1993-94 program whereas Anderson Samplers were used in the 1996-97
program. The small difference in the typical performance of the two samplers may have
contributed to the difference in the results obtained during the two monitoring periods.
4. There are seasonal differences in meteorological conditions in the Pocatello area that
contribute to characteristic seasonal differences in the levels of airborne paniculate matter,
with levels typically being higher in the fall and winter than in the other seasons. Paniculate
matter measurements are available for a full year for the 1993-94 monitoring period.
However, results are only available for October through May for the 1996-97 period as of
this writing. The present lack of results for the historically lower concentration period of
June through September of 1997 means that the seasons with historically lower PM
concentrations are currently under represented in the 1996-97 results.
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5. Since the Remedial Investigation air monitoring effort was completed, FMC's ore has been
mined from a different source. Current feedstocks may be richer in some contaminants of
potential concern.
3. Comment: Should the EPA Superfund risk assessment findings be interpreted that there are
no health effects from air emissions at the site?
Response: No. The Superfund risk assessment process primarily focuses on carcinogenic and
noncarcinogenic risks under a very specific exposure scenario. Air emissions from the FMC plant
have been shown to exceed the National Ambient Air Quality Standards for PM10 on many
occasions. These health-based standards are based on the best scientific information available
at the time. Exceedance of these standards indicates that health effects are possible. Whether
any health effects are observed in an individual or population depends on many variables such as
the types and frequency of exposures, individual response to a chemical, synergistic effects of
other chemicals, lifestyle, vocation, and genetics.
4. Comment Phosphorus was listed as a contaminant of concern but it was not discussed in the
health effects summary in the risk assessment. What are the potential risks and uncertainties from
phosphorus and what attempts did EPA make to quantify these risks and uncertainties?
i
Response: The EPA Superfund Program was aware of the potential importance of releases of
phosphorus and its oxidation products to the air from the EMF Site and, as a result, listed
phosphorus as a chemical of potential concern (COPC) for the air pathway (Table 2-1 of the
Baseline Human Health Risk Assessment [BHHRA]). Efforts were made during the planning and
scoping of the Remedial Investigation and the BHHRA to obtain the information that would have
allowed the potential risks posed by these releases to be quantitatively evaluated in the risk
assessment. However, two factors hampered these efforts and ultimately prevented quantitative
evaluation of these potential risks: the lack of a standard EPA method for measuring the
concentrations of phosphorus and/or its oxidation products in air, and the lack of information of the
toxicological effects of inhaling low levels of these substances over a prolonged period of time.
i
Because of the potential importance of assessing the risks posed by releases of phosphorus and
its oxidation products to the air at the EMF site, EPA investigated the use of non-EPA methods for
measuring the concentrations of these substances in air. Several methods were identified and
considered, but none were sufficiently specific and well validated to generate data that would be
of sufficient quality to meet EPA's guidelines for data useability in risk assessments. Therefore,
EPA reluctantly concluded that it would not be possible to collect useable data on the
concentrations of phosphorus and/or its oxidation products as part of the Rl for the site.
Since toxicological indices (slope factors [SFs] for carcinogenic effects and reference doses [RfDs]
for noncarcinogenic effects) were not available for phosphorus or its oxidation products in EPA's
Integrated Risk Information System (IRIS) database or its Health Effects Assessment Summary
Tables (HEAST) [EPA's standard sources of toxicological information], the EMF project team
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contacted EPA's Environmental Criteria and Assessment Office (ECAO) for assistance. ECAO
conducted a review of the scientific literature for information on the toxicity of phosphorus and its
oxidation products via the inhalation route but concluded that there was insufficient information
upon which to base even a provisional reference dose (RfD). The Agency for Toxic Substances
and Disease Registry (ATSDR) released a Draft Toxicological Profile for White Phosphorus and
White Phosphorus Smoke in June 1994 which concluded that Minimum Risk Levels (MRLs), which
are similar to RfDs, also could riot be established because of insufficient data.
When elemental phosphorus is exposed to the atmosphere it bums spontaneously forming various
phosphorus oxides which absorb and react with moisture in the atmosphere to form phosphoric
acid. When phosphoric acid dissolves in water (as it would if it were inhaled and contacted mucous
secretions in the lungs), it ionizes forming various phosphate ions. Substantial amounts of
phosphate ions are naturally present throughout the body and play an essential role in many bodily
processes. Phosphates and phosphoric acid are also ingredients in many foods and beverages
and are generally regarded as safe in that use by the FDA. Therefore, the small quantities of
phosphoric acid and phosphate that might be absorbed through the lungs as a result of periodically
inhaling the products of phosphorus emissions from the site would not be expected to result in
adverse systemic health effects after being absorbed and neutralized by the body. However, the
emission products would most likely exist as an acidic phosphoric acid mist which could be irritating
to the lungs and respiratory tract when inhaled. Unfortunately, the scientific data needed to
evaluate the potential health effects of inhaling low levels of phosphorus emission products
repeatedly over a period of years is not available.
We acknowledge that because of the unknown, but apparently substantial, quantities of
phosphorus and its oxidation products released from the site to the atmosphere, the agency's
inability to quantitatively evaluate the potential health effects associated with these releases could
represent a significant source of uncertainty in the risk assessment. Unfortunately, because of the
lack of reliable analytical methods for measuring the concentrations of phosphorus and/or its
oxidation products in air and the lack of toxicological information, it is not possible to quantitatively
evaluate either the potential risks posed by these substances or the uncertainties created by
omitting them from the quantitative risk assessment.
t
5. Comment: What is the jurisdiction for land use controls, particularly for building restrictions
associated with radon?
Response: Land use controls, as part of the broader term, "institutional controls," is the use of
existing institutions to achieve environmental protection or the elimination/reduction of
environmental exposure or risk. The most common of these institutions, and the one to be used
at this site to control future radon exposure (as well as to achieve other objectives listed in the
ROD), is the existing legal system for the transfer of real property. The comment appears to have
used the word, jurisdiction, because the FMC plant is on tribal land. With respect to lawful land
transfers, location on tribal land does not significantly change how these land use controls
operate.
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The Tribes have deeded the current PMC property to FMC. FMC is therefore a private property
owner who must obey tribal laws and regulations in the same way as any other owner of tribal
property, or just as any property owner in a state of the United States must obey state law and
regulation. In both cases, private property owners have the freedom to contract, including the right
to sell their private property to a willing buyer. In such negotiations, the seller can place restrictions
in the deed given to the buyer which limits what the buyer receives. These restrictions can and
often do affect the purchase price. Common restrictions, such as those to protect the view of other
property owners or prohibiting various uses like those typically found in zoning ordinances, often
dictate land value. EPA does not usually rely on zoning because it is always subject to change,
exemption or variance by local zoning authorities and therefore offers little assurance of a long term
or even short term effect.
In this instance, EPA anticipates that FMC will enter into a Consent Decree with the United States,
and will agree in the Decree that any sale or transfer of property will include those limitations
contained in the ROD. This means FMC will not only agree to the limitations in the ROD for FMC,
but for any owners who may come after FMC for as long as EPA determines any given restriction
should remain in place.
As described above, legally enforceable deed restrictions will require any future office buildings to
be constructed at the site to use the radon controlling methods specified in the document "Radon
Prevention in the Design and Construction of Schools and Other Large Buildings" (EPA/626/R-
92/016,1994), or whatever radon guidance supersedes it or is otherwise available, applicable and
appropriate. Further, following construction, and annually thereafter, the indoor air shall be tested
for radon. If the radon levels exceed either 4.0 pCi/l, as specified in "Citizens Guide to Radon"
(EPA 1992), or any promulgated standard in effect at the time of these future sampling events,
additional controls shall be implemented to reduce the radon activity below the target level or
promulgated standard. Like all other deeds and deed restrictions, these land use controls will be
recorded and filed with the government office within the jurisdiction, tribal or state, responsible for
a specific area of the site. Recording gives notice to any subsequent purchasers that any future
land transfer will contain such restrictions.
6. Comment: What requirements are in place to insure that the Company-owned properties are
properly dealt with in the future when the plants shut down?
Response: Both Companies will be required to close the plants in accordance with whatever state,
tribal, or federal laws are in place at that time. In addition, at least every five years EPA will review
all relevant data and information for the site as a whole to ensure the cleanup provides adequate
protection of human health and the environment from historic releases.
7. Comment: In the Off-Plant Area where property restrictions such as deed restrictions are being
proposed, will the property owners be compensated in any way for imposition of land use
restrictions?
Response: If an environmental easement is used, the property owner is compensated by the
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Company for not being able to use the property for certain purposes. There also may be some
compensation for placement of a deed restriction since the property owner must agree to the
restriction. Any compensation of property owners is between the Companies and property owners,
and not EPA.
8. Comment: Who makes the decision on what type of land use restrictions will be used in the Off-
Plant Areas?
Response: Based on the findings of the risk assessment EPA determines what types of use(s)
are appropriate for this area. For example, based on available information, consumption of fruits
and vegetables grown in this area would be restricted as well as residential use of certain portions
of the Off-Plant Area and residential use of groundwater.
9. Comment: Would there be potential health risks if you lived on the land now occupied by the
FMC and Simplot Plants •
Response: Yes. EPA did not consider future residential use of the Plant Areas to be likely, and
per EPA guidance, did not evaluate this scenario in the risk assessment. However, the risk
assessment did evaluate potential residential use of the Company-owned property north of the
fence lines and along the 1-86 right of way. Potential risks in this area are elevated and therefore
require institutional controls to prevent future residential use but are within an acceptable risk range
for industrial workers. The levels and types of contaminants in the Plant Areas are comparable to
the area along the 1-86 right of way and the potential risks would be expected to be equivalent.
This is the basis for institutional controls in the Plant Area which will prohibit any future residential
use.
10. Comment: During the RI/FS, has EPA conducted any long term epidemiology studies on
possible health effects?
Response: No. EPA uses the risk assessment process as a tool to provide a nationally consistent
basis for making decisions with a minimum of data. Epidemiological studies require large
populations, an understanding of other* risk factors (e.g., lifestyle, non-site exposures, etc.), and
large amounts of data. It is unlikely that large studies of this type would yield any meaningful
conclusions that would aid a site.' cleanup. However, if there was data that indicates that the site
may pose more immediate health effects, this information would have been considered in
developing a cleanup plan for the site. This type of information is typically identified during the
listing of the site on the NPL and/or during scoping of the RI/FS. In addition the Agency for Toxic
Substances and Disease Registry (ATSDR) has the responsibility for evaluating potential human
exposures (past, present, and future) to site related contaminants. ATSDR has already completed
one health study on the Fort Hall Indian Reservation and is in the process of conducting health
consultations for air, groundwater, and soil at the EMF site. At any time, if new information
becomes available that indicates the site remedy is not protective, as defined under CERCLA, EPA
will consider amending the Record of Decision for the site.
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11. Comment: FMC is a large company and can make decisions regarding a cleanup without
EPA's involvement. Why is EPA involved in this process?
Response: Section 104(a)(1) of CERCLA requires EPA oversight of Company field activities and
review of deliverables. In 1991, FMC and Simplot signed an Administrative Order on Consent
(AOC) with EPA for the RI/FS at the EMF site. Under this agreement the Companies voluntarily
agreed to allow EPA, the state, and tribe to provide oversight throughout the process, and EPA
then selects the remedy for the site. After the ROD is finalized EPA will negotiate a consent
decree with the Companies for the design and implementation of the cleanup plan. This agreement
will require EPA oversight throughout the cleanup process.
12. Comment: Will there be new jobs associated with the site cleanup?
Response: At FMC and Simplot, there may be some additional increase in employees, particularly
contract workers and temporary employees during some of the construction activities. The
Companies should be contacted directly regarding any potential employment opportunities.
13. Comment Will workers doing the cleanup work be required to wear protective equipment and
meet the requirements of the Occupational Safety and Health Administration (OSHA)?
Response: Yes. Any work at the site will be preceded by development of a Health and Safety Plan
designed to meet OSHA and plant requirements. All workers will be expected to comply with the
Health and Safety Plan.
14. Comment How does EPA know that groundwater and soil contamination have not spread
further than the area sampled?
Response: During the Remedial Investigation, soils were sampled out to a distance of three miles
from the plants in all directions. The results showed that the levels of soil contaminants decreased
with increasing distance from the plants. The concentrations at three miles away were either
indistinguishable from background or well bellow any risk-based level of concern. Groundwater
monitoring was conducted at the plants and in the Off Plant areas. The same pattern of
decreasing concentration with increasing distance was observed, and drinking water standards
were met in the groundwater before leaving the Company owned properties.
15. Comment: Is it true that groundwater currently meets drinking water standards north of the
Company-owned property?
Response: Yes. Concentrations of contaminants in groundwater do not exceed drinking water
standards known as Maximum Contaminant Levels (MCLs) in wells on Company owned properties
north of Highway 86, at Batiste Spring or Swanson Road Springs. Groundwater concentrations are
also below MCLs (and generally are at background levels) in wells on non-Company owned
properties such as the City of Pocatello land north of Highway 86, and the Chevron tank farm and
Rowlands property.
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16. Comment: What steps are being taken to prevent further spread of groundwater
contamination?
Response: The proposed plan included three elements to address groundwater contaminants.
These elements are as follows: 1) Control sources of contamination such as capping old pond
areas; 2) Groundwater extraction to maintain hydraulic control and remove some contamination;
and, 3) Groundwater monitoring to ensure that the selected remedy remains protective.
17. Comment: Is the Portneuf River a hydraulic barrier to groundwater movement?
Response: Yes, based upon available information. The Rl evaluated groundwater elevations at
more than 140 wells during at least 10 quarterly sampling events. Mapping of these elevations
provides information on which way groundwater flows (high elevations to low elevations). It also
shows concentrations of chemicals in groundwater declining down-gradient. Groundwater at the
site is flowing from the foothills of the Bannock Range into the Michaud flats. On the east side of
the river water is also flowing down gradient toward the river and can't flow past the river due to
higher groundwater elevations on the west side.
18. Comment: What is the rationale for proposing FMC pump groundwater rather than just
propose institutional controls?
Response: The intent of this alternative, as described in the Proposed Plan, was to maintain
hydraulic control of the water and prevent any further spread of contamination. For the ROD this
alternative was replaced with a contingent groundwater pump and treat remedy. This change was
made since the area of contamination does not appear to be expanding and groundwater meets
drinking water standards before teaching the springs. If the contingency is employed groundwater
extraction will consist of installing extraction wells in the northern portion of the FMC plant, and
extracting groundwater from the shallow aquifer at a rate sufficient to capture the contaminated
groundwater in which concentrations of contaminants of potential concern exceed MCLs or Risk-
based Concentrations (RBCs). Extracted groundwater would be treated prior to discharge or re-
use within the Plant. Bench-scale and/or pilot testing may be required during treatment plant
design. Implementation of the extraction system would be triggered by a set of criteria in the ROD
for determining plume expansion and exceedence of risk-based drinking water levels in
groundwater.
19. Comment: The Proposed Plan indicates that extracted groundwater could be put into the
Portneuf River without treatment. What is the justification for this aspect of the Proposed Plan?
Response: It is possible that groundwater extracted for hydraulic control would already meet
drinking water standards and other water quality standards (i.e., quality standards for aquatic
organisms). This is primarily due to the fact that extraction wells on the northern edge of the plume
would also withdraw large volumes of clean water. In this case the water could be discharged to
the Portneuf River without treatment. Water extracted at Simplot will be used in their process,
either with or without treatment depending on quality. At FMC the cleanup plan will require
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treatment if the contingent groundwater extraction system is implemented.
20. Comment: Are PMC and Simplot going to 'treat* the contaminated groundwater that will be
extracted under the proposed remedy for the site?
Response: At Simplot, extracted groundwater will be utilized in plant processes. Further testing
is required to determine if this water will require any treatment. At FMC, the ROD requires
treatment of groundwater if extraction becomes necessary.
21. Comment: Under the plan, how long will groundwater extraction at Simplot take place?
Response: The extraction system will continue to operate as long as there is contamination
leaching from the gypsum stack and groundwater contaminants exceed risk or health-based levels.
This may require operation of the system after the gypsum stack is closed and until groundwater
levels reach acceptable levels.
22. Comment: How will actions in the site remedy dean the contaminated aquifer?
Response: The actions in the ROD are directed at reducing sources of contamination to the
groundwater and allowing for natural recovery of the aquifer over time. Natural recovery of the
aquifer may take several decades and relies on physical or biological processes (unassisted by
human intervention) to reduce contaminant concentrations. Performance monitoring is a critical
component of this remediation approach because monitoring is needed to ensure that the remedy
is protective and that natural processes are reducing contamination levels as expected.
23. Comment: Will there be a third party review of the remedial design of the cleanup plan?
Response: Currently the State of Idaho, Shoshone-Bannock Tribe, and EPA will be reviewing
design documents.
24. Comment: How many wells are in the Off-Plant Area and how often are they sampled?
Response: There are approximately 20 wells off site. During the Rl from 1992-1996 they were
sampled every 3 months. These wells are now being sampled twice a year.
25. Comment: It does not appear that Alternative 03 (Institutional Controls and Monitoring in the
Off-Plant Area) would offer adequate controls for this area. What is the justification for this
alternative?
Response: The risks found in most of the Off-Plant Area were not high enough to justify the
significant cost of a soil cleanup. Use of institutional controls, such as deed restrictions or
easements, would provide the same level of human health protection but at a substantially lower
cost. In addition, there are only two privately-held parcels of land in this area. All other parcels are
owned by either the Company or the City of Pocatello, and deed restrictions are already in place
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prohibiting residential uses.
26. Comment: The Plan does not say anything about the slag piles at FMC. Do these piles
represent a risk?
Response: The slag is a glass-like material and is not a major source of contamination to either
groundwater or air. Slag does emit gamma radiation at levels which can pose a risk to humans,
particularly if an individual is in close proximity to it for extended periods of time. FMC has
voluntarily entered into an agreement with EPA to no longer sell and distribute this material outside
of their facility. FMC workers who work on or near the slag piles are partially shielded from the
radiation while working in vehicles and heavy equipment.
27. Comment In 1994, EPA issued a Notice of Violation under the Resource Conservation and
Recovery Act (RCRA) at FMC, which has yet to be resolved. Without knowledge of what these
violations were for, how can the public evaluate the adequacy of the Proposed Plan?
Response: While EPA cannot divulge the details of the RCRA case, we can say that the violations
are primarily related to FMC's compliance with RCRA closure requirements at the operating waste
disposal ponds. RCRAfegulations require closure, within specific time frames, of hazardous waste
units that do not meet certain standards. RCRA was designed to prevent impacts to public health
and the environment through specific record keeping, engineering controls, monitoring, and
reporting requirements. While all of the RCRA violations are considered serious, not all violations
are necessarily correlated with i) specific impact on the environment or direct threat to human
health. Implementation of the Superfund ROD will help address the most significant risks
associated with the past uncontrolled release of hazardous substances at the site, and actions by
the RCRA program will help prevent future impacts to the environment and help bring the facility
into compliance with the current RCRA requirements.
28. Comment: Is it possible for there to be an independent analysis of the RI/FS?
Response: Yes. Based on a request from a newly formed citizen group called the Pocatello
Environmental Council, an independent review of the RI/FS is being conducted through the
Technical Outreach Support for Communities Program of Oregon State University. While the
results of this review may not be available until after the ROD is signed, if new relevant information
indicates that the Superfund remedy is not protective, EPA will consider amending the ROD.
29. Comment: During the course of the study of the site, did anyone contact hospitals, doctors,
or schools to learn of what impacts the site may have on the community?
Response: No. However, EPA did talk to a number of individuals representing a cross section of
the community throughout the RI/FS process. Even before the Rl began. EPA representatives met
with community members to learn about their concerns with the site. Information from these
discussions was incorporated into the site community relations plan and scope of the RI/FS. At
that time and throughout the six-year site investigation, no such concerns were specifically
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identified for EPA to follow up on. In addition, the Agency for Toxics Substances and Disease
Registry (ATSDR) has conducted one health study on the Fort Hall Reservation (and is in the
process of conducting follow-up to this study) during which hospital records were reviewed and
interviews conducted to determine the incidence of respiratory diseases on the reservation as
compared to a control location.
30. Comment: How will the information that ATSDR is developing be used by EPA it its decision
making?
Response: EPA will review ATSDR findings as they become available. If any new relevant
information is presented (which was not available during the Rl) indicating that the remedy is not
adequately protective, EPA will consider amending the site cleanup plan as appropriate in order
to ensure that it is protective of public health and the environment.
31. Comment Why does the Plan only require capping of waste areas rather than excavation and
treatment of contaminated soils?
Response: Placement of a thick cap over the old pond areas would reduce the risks from
incidental exposure to contaminants and reduce infiltration of water into the wastes. During the
RI/FS there were no readily available proven technologies for treating the contaminated phossy
wastes and soils in the old ponds should they be removed. In addition, excavation of these wastes
which are currently covered with some soil would pose a very significant danger to workers from
elemental phosphorus which ignites when exposed to air. In addition to the dangers from fire are
the inhalation risks from phosphorus pentoxide and phosphine gas. These very real dangers and
significant costs do not justify the potential benefits of removing and treating this material.
32. Comment: What type of support has EPA provided the Tribes on environmental issues?
Response: Since 1991, the EPA Superfund program has funded a cooperative agreement with the
Shoshone Bannock Tribes for technical support at the EMF site. Funding has been provided at
approximately $50,000 per year. This money has allowed for a full time tribal representative to
participate in meetings, review and comment on'documents and data, and communicate with the
Business Council and Land Use Commission on relevant data, key decisions and general progress
in the investigation of the site. In addition to the Superfund support, a variety of other EPA
programs have provided the Tribes with ongoing; financial and technical support in addressing a
variety of environmental issues.
33. Comment: The Proposed Plan indicates that it must meet state and federal environmental
siting laws and regulations. What about tribal laws?
Response: Tribes have the ability to set laws and regulations for reservation lands. EPA
interprets the requirement to meet state and federal laws and regulations to include tribal laws and
regulations. One of the key steps of the Feasibility Study is to identify all Applicable and Relevant
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or Appropriate Requirements (ARARs) for the various alternatives being considered3. During this
process the Shoshone Bannock Tribe did not identify any specific laws or regulations that should
be considered an ARAR for the site. EPA has also reviewed the Law and Order Code of the
Shoshone Bannock Tribe and the Ordinances and Policies to identify any potential tribal ARARs.
Based upon this review, EPA has found no tribal ARARs that would apply to the selected remedy.
34. Comment: Are the tribal air quality regulations considered an ARAR?
Response: The boundaries of the Fort Hall Indian Reservation give the Shoshone Bannock
Tribes jurisdiction over most of the FMC Plant. Therefore, Tribal air regulations established to
control ongoing air emissions are binding just as state regulations are outside of the reservation.
However, in this case the Tribal air regulations are not applicable because Superfund is not taking
actions that will result in air emissions. The Tribal regulations would be binding on additional
consols put into place by EPA's air program as a result of a FIP.
Specific Comments from the Shoshone Bannock Tribes
The following is a summary of specific comments received from the Shoshone Bannock Tribes on
the EMF Proposed Plan and Draft Record of decision:
1. Comment: The ROD does riot include action for air emissions based upon findings of the
human health risk assessment arid ecological risk assessment. Additional action associated with
the air pathway is justified based upon the timeliness of implementing a FIP/TIP and the high
degree of uncertainty in the air portion of the RI/FS at this site. The five-year review process may
not ensure protection of human health or the environment from ongoing emissions.
Response: EPA is in agreement with the Tribes' concern that actions to control air emissions from
the FMC plant need to be undertaken expeditiously. The Agency is also in agreement that
considerable work needs to be undertaken before additional air emission controls are in place at
FMC. The following outlines EPA's commitment to address these issues and how the agency will
use its different programs to control air emissions from the operating facility.
i
What EPA is doing to address air issues
In recognition of the many concerns witrrair quality in the region, and delays in implementation of
the necessary controls, EPA's air program has made the regulation of air emissions at FMC a
priority. Here are the three main categories of concern, and what EPA is doing about the problem:
1) Particulate matter. A federal implementation plan to impose controls on FMC to reduce
paniculate emissions by about 67% is in the final stage of preparation, and will be proposed in the
Federal Register later this year.
If no action is being proposed for a specific media, such as air, then no ARARs apply.
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2) Radionuclide emissions: EPA's air program is directing FMC to conduct additional testing this
summer to establish new emission factors for compliance with the emission standard for this
hazardous pollutant. EPA will be on site to provide close oversight of these tests.
3) Phosphine and hydrogen cyanide emissions: FMC has notified EPA that emissions from
waste ponds have on occasion exceeded CERCLA reportable quantities for these chemicals.
EPA's removal program has continued to monitor the situation to insure there is no immediate
threat to the public or the environment from these emissions. In order for these emissions to be
addressed EPA Headquarters must determine if a source category is warranted for phosphorus
facilities. If such a category is warranted, EPA Headquarters must establish a standard for these
emissions as required under Section 112 of the CAA. In addition, since the major source of these
emissions are the operating RCRA ponds, EPA's RCRA program is in the process of working with
FMC to establish a technology-based emission standard.
Limits on Superfund as a tool to regulate FMC's ongoing operations
As stated previously in this document the Superfund program is unique in that it provides for the
cleanup of past hazardous waste releases and of hazardous waste requiring emergency response.
Congressional enactment of the Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA) was the solution to the gap in Federal environmental authority and it is
intended to augment other Federal and State authorities. If a facility is subject to state or federal
rules for an ongoing release then the Superfund program will defer control of that release to the
appropriate authority. For this reason, Superfund will not be involved in implementing items 1-3
above. Instead those actions will be carried out by the Air and RCRA programs.
The Superfund Record of Decision includes only those actions which are appropriate to site
"cleanup" and risks associated with past practices. Despite any uncertainties in the risk
assessment the Superfund program believes that collection of additional data or further analysis
of continued air monitoring data would not alter the findings and ultimate basis for the actions in
the ROD. Air monitoring being conducted by the EPA air program and Shoshone Bannock Tribes
will continue for the foreseeable future.
t
2. Comment: The fluoride levels in sagebrush and soils identify an increase of contamination in
the area and the Tribes believe source control of fluoride emissions is warranted. The Idaho
standard for fluoride content in vegetation used for feed or forage for livestock is not protective of
other species, specifically, migratory birds.
Response: The sources of fluoride are primarily from active facility operations and not subject to
direct control under Superfund. Nevertheless, the ROD does include a requirement for continued
monitoring of fluoride in the environment due to the potential risks calculated in the ecological risk
assessment for plant and wildlife species of the sagebrush steppe ecosystem. If the monitoring
indicates fluoride levels may be increasing then additional actions, including some source controls,
may be warranted. In such a case EPA would then evaluate the sources and work with the state
and Tribes to determine how best to achieve the necessary source controls. Currently, based on
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the findings of the ecological risk assessment, source controls or cleanup actions are not
warranted.
3. Comment: The Tribes are concerned with the uncertainty associated with the ecological risk
assessment findings for the Portneuf River, waterfowl, or sediment. The Tribes request CERCLA
design and implement a monitoring program to ensure contaminants are not entering the Portneuf
River via the National Pollutant Discharge Elimination System (NPDES) regulated discharge. The
Tribes also request further study of the area be conducted in order to determine the validity of the
modeling used in the ecological risk assessment.
Response: Based upon the findings of the Rl, the EPA Superfund program does not believe that
the FMC Industrial Waste Water Discharge is a continuous or significant source of contaminants
to the Portneuf River. This conclusion is based on analysis of discharge water and sediments in
the vicinity of the outfall. However, EPA agrees that further evaluation of this discharge, including
additional monitoring, may be warranted. Since this is an ongoing discharge and not a past
practice, it is appropriate that this work be conducted through the EPA NPDES program.
With regard to concerns with the uncertainty of the ecological risk assessment EPA does not agree
that further study is necessary. At this site maximum use was made of site-specific exposure data
for the risk assessment, thereby reducing a major source of uncertainty typically associated with
the use of non site specific models. Fluoride exposure estimates for wildlife were based on
statistically designed sampling and analysis of representative food items, hence the modeled dose
estimates are considered to have a high degree of reliability. Toxicity testing and analysis of
sediments provide adequate information to evaluate potential contaminants to the Portneuf River,
which were judged to be minimal. In general, with the exception of analytical uncertainties for
fluoride, the conservative assumptions used in the risk assessment are more likely to overestimate
rather than underestimate the risks of adverse effects at the site. With the exception of the
marginal risks associated with fluoride, potential site related risks were not identified for the
riparian, riverine, or mudflat habitats associated with the Portneuf River. These are the ecosystems
of greatest ecological concern in the site vicinity.
4. Comment: The ROD proposed implementing institutional controls in the form of environmental
easements, deed restrictions, or zoning. With what jurisdiction entity will these easements, deed
restrictions or zoning be filed? Should this option be carried forward the Tribes request these
issues be clearly defined by all parties/ The tribes assert and maintain jurisdiction within their
reservation boundaries.
Response: (See the response to previous comment number 5 on page B-12). Like all other deeds
and deed restrictions, these land use controls will be recorded and filed with the government office
within the jurisdiction, tribal or state, responsible for a specific area of the site. Recording gives
notice to any subsequent purchasers that any future land transfer will contain such restrictions.
EPA will work jointly with the Tribe to develop controls within the reservation boundary that will
recognize the Tribes jurisdiction and meet the objective of the ROD.
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5. Comment: The Endangered Species Act and the Migratory Birds Treaty Act should be added
to the ARARs for this site. Migratory birds are affected by off-site migration of contamination.
Response: Based upon the risk evaluation of benthic invertebrates, waterfowl, shorebirds,
songbirds, semi-aquatic mammals, and shrubs, potential site-related risks were not identified for
the jurisdictional wetlands or listed species of riparian, riverine, and mudflat habitats with the
Portnuef River. With the exception of potential impacts to migratory birds from exposure to
contaminants in FMC open RCRA ponds, there is no other information that would suggest
migratory birds are being affected by contamination at the site. The EPA RCRA program, which
regulates the FMC ponds, is aware of the trustee concerns with regards to impacts to migratory
waterfowl and has been working with FMC to solve this problem through eventual elimination of
ponds and open bodies of water. The ROD does not include actions that would result in additional
areas of standing water and therefore the Endangered Species Act and Migratory Birds Treaty Act
are not applicable.
6. Comment The ROD proposes a monitoring program to assure the contamination plume does
not increase at the facility. The Tribes do not believe this option is the best balance of benefits and
tradeoffs. Natural mixing of clean and contaminated water does not justify a no treatment option.
Response: Contaminated ground water exists at more than 85 percent of the sites on the National
Priorities List (NPL). The goal of ground-water remediation at Superfund sites is to protect human
health and the environment through a combination of short-term measures (e.g., provision of
alternate water supplies) and long-term measures to restore ground-water quality appropriate for
its beneficial uses. Remedial action for contaminated ground water generally is warranted when
EPA determines, based on the results of the baseline risk assessment, that the contamination
poses a current or potential threat to human health or the environment. Additionally, where the
ground water is currently used (or is potentially usable) as a drinking water supply, exceedance of
Maximum Contaminant Levels (MCLs) and non-zero Maximum Contaminant Level Goals (MCLGs)
established under the Safe Drinking Water Act also may be used as the basis for taking a remedial
action. The goals of the long-term ground-water cleanup program are to return usable ground
waters to their beneficial uses wherever practicable, within a time frame and cost that is reasonable
given the particular circumstances of the site! When restoration of ground water to beneficial uses
is not practicable, EPA expects to prevent further migration of the plume, prevent exposure to the
contaminated ground water, and evaluate further risk reduction.
Information collected during the Rl indicates that some areas of former unlined ponds are still
contributing chemicals to the groundwater to varying degrees and this will continue for some time
regardless of reductions in infiltration. The materials beneath the former unlined ponds that contain
these residual concentrations of contaminants are fine to very fine grained soils and wastes, which
are above the water table. Extraction of groundwater adjacent to these areas would result in
capture of impacted groundwater, but would not significantly reduce the time required to reach
MCLs. because with very low levels of infiltration (5 percent), the source material will continue to
release contaminants to the groundwater over the next several decades at nearly the same
concentration (but at reduced quantities) as when the old ponds were in service. Additionally, to
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capture the groundwater over such a broad area would require many pumping wells and an
extensive piping system. It is also likely that large quantities of unimpacted (clean) groundwater
would be extracted by the pumping wells. Large quantities of water would require treatment,
significantly increasing the treatment costs, without any appreciable environmental gain.
However, the goals of the long-term groundwater cleanup will be achieved at this site through
institutional controls to prohibit use of water for drinking purposes, continued monitoring, extracting
groundwater at Simplot, and, if necessary, implementation of the contingent groundwater extraction
system at FMC.
7. Comment: The tribes request there be consistency with the RCRA program in the closure of
pond areas at the facility. The tribes believe the most conservative measures must be utilized in
all areas where definitive data is lacking and that the most stringent closure requirements are used.
Response: The selected Superfund remedy for capping old pond areas is consistent with many
of the closure requirements of RCRA. The RCRA program can be very prescriptive as to how a
landfill cap is constructed due to specific provisions in the regulations. Superfund is bound to
consider a variety of factors in coming to a remedy decision including cost and risk reduction.
Nonetheless EPA believes that the selected Superfund cap remedy meets the fundamental goals
for a RCRA cap. That is, it minimizes infiltration and controls releases to the extent necessary to
protect human health and the environment. At the old pond areas the potential risk reduction
benefits to be gained by using the most stringent closure procedures do not justify the additional
costs associated with multi-layer impermeable caps or excavation and treatment of wastes. In
addition groundwater monitoring and five year reviews will be conducted indefinitely to ensure that
the remedy is protective. This may not necessarily be the case at open ponds that are still
operating which are subject to the specific closure requirements of RCRA.
8. Comment: The risk assessment for the site did not address risks to tribal culture from
contamination on tribal lands. These risks should be addressed due to the essential
interconnectedness of the tribal community, its religions, and environment.
i
Response: EPA acknowledges that the standard risk assessment process was not designed to
evaluate risks to Tribal cultural and spiritual values. Clearly tribes and EPA need to work together
in the future to develop tribal-specific risk assessments and risk management strategies to address
these types of concerns. However, EPA has considered the Shoshone Bannock Tribe a partner
during the design and conduct of the EMF site risk assessment. EPA sought input from the
Shoshone Bannock Tribe during every phase of the Rl and Risk Assessment.
During the Rl both the Shoshone Bannock Tribe Superfund coordinator and representatives of U.S.
Fish and Wildlife Service were involved in scoping the ecological risk assessment, selecting
sampling locations in the field, and interpreting the results. Throughout this process every attempt
was made to factor in tribal and agency concerns and include plant and animal species that were
of particular interest. Maximal use was made of site-specific exposure data and EPA's confidence
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in the results of the ecological risk assessments is considered to be high.
With respect to the human health risk assessment EPA did evaluate exposure to contaminants in
air, soil, groundwater, and from consumption of home-grown produce. As with the ecological risk
assessment many conservative assumptions were used to account for uncertainties. In the Human
Health Risk Assessment exposure to contaminants from consumption of home-grown produce
were calculated using distributions from the U.S. Department of Agriculture Nationwide Food
Consumption Surveys. These surveys take into account the physical characteristics (age, body
weight, etc.) of individuals responding to the surveys and include many demographic subgroups
within the overall population. EPA then took this information and estimated homegrown produce
intake rates using a Monte Carlo simulation since individuals do not consume fixed amounts of
homegrown produce. We believe this analysis provides a reasonably accurate estimate of potential
exposures from home-grown produce and may provide a benchmark for other types of exposure
such as from native plants used for ceremonial or medicinal purposes.
10. Comment: There appears to be considerable uncertainty in the ecological risk assessment
particularly related to the bioassay of benthic invertebrates near the IWW outfall and use of
modeling information to assess exposures to wildlife. The Tribe requests that the ROD include
further study of the area in order to determine the validity of the modeling.
Response: See response to previous comment number nine. With regards to modeling of
contaminants and ingestion rates, EPA recently reevaluated the sediment ingestion rates for
waterfowl. In an August 15, 1997-letter the Department of Interior suggested considering a
sediment ingestion rate of 18 percent for mallards, rather than the 3.3 percent value used in the
ecological risk assessment. Apart from the question of which value provides a better sediment
consumption estimate (EPA's is from a published source and is presented in USEPA guidance; the
Department of Interior reference is from a site-specific study at another location in Idaho), the
adjustment makes little overall difference in the risk calculations. In fact, the risk assessment
already assumed a 18% sediment ingestion rate for another waterfowl species at the site, the
spotted sandpiper, and the risks for that species (Hazard Quotient = 0.14) was comparable to the
risks to the mallard (HQ = 0.17). For both species, sediment is only a small part of their total
exposure, since most (>90%) of their exposure is through ingestion of contaminated prey (see
Table 4-9 in the risk assessment report). Even if sediment exposure were increased by a factor
of 18/3.3 = 5.4545 for the mallard, its total exposure would increase only by about 5%. This is not
nearly sufficient to cause a change in the predicted risks (i.e., the mallard HQ would increase from
0.17 to approximately 0.18).
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Shoshone-Bannock Tribes
Comments on EPA Proposed Plan / Record of Decision
Eastern Michaud Flats Superfund Site
Inherent and fundamental differences exist between Native American and European perspectives
on environmental management. European culture examines the natural world in a stepped
approach to satisfy the scientific principles involved. Science by it's very nature is based on
observations and facts that can be verified, reproduced and visible to anyone. This alone creates a
fundamental difference with the Native American perspective of the natural world. Fundamental
to Native American culture is the interconnected nature of species and relationships. Sacredness is
embeded in all forms • plants, animals, water, air and the natural landscape. Nature possesses a
symbolic content with interpretation of these symbolisms derived from traditional culture. This
holistic approach is a deep rooted cultural tradition, passed on from generation to generation
European culture creates its own sacred places in churches, wards and synagogues. This is not so
with Native American. Native Americans are attached to the land, water and life forms that come
from it. Spirituality is interwoven between individuals and the natural world with the belief that all
things share a creator and creation. Sacred sites are not located at a single street address or
within the walls of a church but to the reservation as a whole, the land, the life it supports, the
water that runs through, all natural processes. Identification with plants and animals is a key
characteristic of Indian culture. Plants and animals represent ties to generations past and present.
This belief of interconnectedness is translated through their everyday lives and cultural traditions.
Ceremonies serve an integral role in native American culture as they mark marriages, namings,
funerals, first kills and intertwined with ceremonies and everyday activities are the relationship
with plants, animals, gathering rituals, people, ancestors, water, sun and air.
All plants hold healing powers or qualities for both the body and spirit. An example sage brush,
which is a most respected plant, signifies purification and is used in traditional Native American
rituals. Water is referred to as the life blood of the reservation, it is used in spiritual ceremonies at
sweat lodges which may be likened to the use of "holy water" in a Catholic church or Baptismal
water used in other Christian religions. There is not a distinct separation of religion from plants,
animals, and other land forms provided by the creator.
Scientific risk assessments, ecological assessments and overall management of environmental
media conflict with traditional views. To develop an acceptable risk to humans, animals and plants
by allowing for an acceptable amount of contamination is contrary to Native American ways.
It is our hope that with this condensed version on Native American culture the U.S. EPA and
industries involved with the Eastern Michaud Flats Superfund Site will gain a better appreciation
and understanding of the significance environmental contamination has on traditional values,
culture and all Shoshone-Bannock people on the Fort Hall Indian Reservation.
In spite of the philosophical differences, the tribes believe there is strong scientific argument,
based on uncertainties with the Remedial Investigation, Human Health Risk Assessment and
Ecological Risk Assessment, to support a non-concurrence with the Proposed Plan/ Record of
Decision for tlie Eastern Michaud Flats as currently drafted.
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AIR
The ROD does not include action for air emissions based upon findings of the human health risk
assessment and ecological risk assessment. The ROD proposes to relinquish this portion of
remediation to the air program, with a five year review period, at which time if it is evident that
continued emissions have occurred then additional action under CERCLA will be considered.
Although the air program is the authority which should regulate and insure compliance is
maintained with the NAAQS, NESHAPS and other sections of the Clean Air Act, the Tribes
request CERCLA address the uncertainties associated with this pathway prior. Concerns lie in
the timeliness of implementing a FEP / TEP and believe continued emissions will and are occurring
that may pose significant risks to public health and the environment. A five year review process
may not ensure protection of human health or the environment from emissions.
There was a high degree of uncertainty in the air portion of the RI/FS at this site. However, the
baseline risk assessment (BRA) came out with results quantifying the risks each pathway posed
and used these risks to steer remediation options. Following is a list of uncertainties associated
with the air .pathway the Tribes believe need to be addressed, justifying additional action under
CERCLA:
• Phosphorus Pentoxide (P20$) was never characterized due to industries claim of
inadequate or lacking technologies. Data suggests there is considerable emissions from
this chemical. The literature available on the chronic effects of exposure to P20S is
lacking. The tribes suggest ATSDR or the National Toxicology Program determine health
effects from exposure to this chemical and techniques for development of methods to
monitor this chemical.
• Air monitoring stations were not placed in locations that would intersect emission plumes
from the plants. The intent of the air monitoring stations were to calibrate the modeling
effort; do to problems with the model data from the monitors was used. Had the monitors
been located in the direct pathway of the emission plumes, the results may have been
significantly different, changing the risks measured from the air pathway and triggering
additional remediation. Data from the monitors was used in calculating exposure for the
industrial scenario It would be expedient to place air monitors on-site to actually monitor
concentrations in ambient air typical of what on-site workers would experience.
• Prior to the risk assessment and the RI/FS the FMC facility used ore from the Gay Mine.
Since 1994 the facility has been using ore from the Dry Valley Mine, which has a unique
chemical composition and is more enriched in metals and radionuclides. In addition, three
furnaces were operating during air monitoring, current operation uses 4 furnaces. Logic
follows that emissions from production using ore more enriched with metals and
radionuclides would result in contaminants more concentrated. What impact the added
furnace operation and the change of ore contributes to contaminants in the air and soil
pathway and the overall risk assessment numbers needs to be addressed.
Radionuclides at this site seem to be falling through the regulatory cracks. The Nuclear
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Regulatory Commission regulates manmade radioactive material, the RCRA program
regulates chemical wastes. CERCLA, through the RI/FS could have addressed this issue,
or referred it to the NESHAPS program, but it has not been addressed. NESHAPS
standard for compliance at this facility is based on one source of radioactive emissions, the
stack emissions from the calciner scrubbers. The mandate of NESHAPS calls for all
sources to be considered when developing permit limits. The emission from the ponds, as
well as potential other sources (ground flare and furnace flares) need to be quantified and
considered. This issue is of great concern to the Tribes. We request CERCLA work with
the NESHAP program to assure these other sources are accounted for and the
radionuclide issue is fully addressed through a regulatory program.
The ATSDR Fort Hall Study indicated there was an increase in bronchial problems,
pneumonia and respiratory illness in tribal members living on the Fort Hall Reservation.
Statistical significance could not be assured due to the small population of tribal members.
Perhaps this study should be expanded to include the surrounding communities. This
would provide an added degree of assurance to what the actual risks are.
FMC has been conducting an epidemiological study of its workers over the years. The
Tribes believe this study could be relevant toward assessing actual risks to on-site
workers. The Tribes request this study be evaluated.
SOILS
Soil samples in the EMF area found elevated levels of carcinogens, chemical and
radiological and non-carcinogen contaminants 1.5 to 2 times above background levels in
residential areas. Initially consumption of homegrown produce was a pathway of concern
and one of the determining factors resulting in HQ numbers over 1 which would trigger a
remediation response. After further analysis this pathway was determined to be lesser of a
risk, resulting in no remediation for off-site soils. Of concern is the degree of uncertainty
in transfer factors between soil/plant, plant/animal, bioavailability through the food chain
and ultimately actual levels of contaminants in the soil. The COPC continue to be present
in the air, are in the soil, and the potential for impacts is expected to increase over time
with continued air emissions. It makes little sense to remediate an area that is expected to
be re-contaminated. To quantify risks posed by this site in terms of chronic daily dose
while exposure continues and then develop remedial actions based on those risk numbers
provides a false sense of security to the general public. Continued air emissions and
resulting deposition on soils may increase the risks. The Tribes request the CERCLA
program address the existing air emission issues and assure source controls are
implemented before signing off on a ROD for this site.
The Tribes believe the need for source control of fluoride emissions is warranted at this
time as is a monitoring program and request this remedy be integrated. The fluoride levels
in sagebrush steppe and soils clearly identifies an increase contamination in the area. In
addition, on going studies in the area have documented increased fluoride levels in hay
fields surrounding J R Simplot and FMC These crops are used to feed buffalo, horses,
-------
cattle, sheep and other livestock. The tribes graze buffalo, cattle and horses in the Fort
Hall Bottoms area as close as 3 miles from the plants. Approximately 150 horses and 300
Buffalo are grazed year round in the Fort Hall Bottoms area. During winter months they
are supplemented with alfalfa, some that is grown in the EMF area. Approximately 2000
head of cattle graze in the area 6 months out of the year, from October through May.
Historical problems in the area documented fluorosis in livestock. The Tribes believe it is
warranted to identify, through local veterinarians or ranchers adverse effects elevated
fluoride levels may have on livestock in the area through monitoring or a study.
The Rod identifies IDAPA as an action specific ARAR for fluoride concentrations in
ambient air which results in total fluoride content in vegetation used for feed or forage for
livestock. This standard is not protective of other species, specifically, migratory birds. It
is questionable if this standard is enforced within the state. Fluoride levels in the EMF area
reflect elevated levels above this standard. The tribes believe source controls are needed
to reduce emission to a degree protective of all flora and fauna in the area.
ECO'LOGICAL RISK ASSESSMENT
SURFACE WATER
The ecological risk assessment found no risk to the Portneuf River, waterfowl or
sediment. The Tribes believe this is an area of uncertainty and request for some type of
control to be put on the discharge point through the NPDES. The NPDES permit which
FMC operates under is at least 10 years outdated and monitors for minimal parameters.
The Tribes request CERCLA structure or implement a monitoring program to ensure
contaminants are not entering the Portneuf River via the NPDES discharge Cadmium was
found in the sediment of the Portneuf River at 2.5 times above background. The source of
this is unknown but at question is the IWW ditch, where frequent upset/breakdown
conditions have documented loading of the Portneuf River with contaminants. •
Our information is the bioassay study of benthic invertebrates in the Portneuf
River, near the IWW outfall was conducted without oversight and an approved
CERCLA sampling plan. Regardless, local organisms were used to identify if
adverse effects from contamination had occurred. Local organisms would have
been previously exposed to environmental contaminants and through the natural
selection process may have mutated to develop resistance. This point is made to
communicate one more factor contributing to the tribes uncertainty of the
Ecological Risk Assessment findings.
The Tribes have received information from the U.S. Fish and Wildlife indicating modeling
of contaminants for different species of wildlife, based on ingestion rates, can be
inaccurate when compared to actual scenarios at existing superfund sites. The tribes have
expressed concern for some time as to the findings of the Ecological Risk Assessment.
We request the ROD include further study of the area in order to determine the validity of
-------
the modeling.
The ROD proposes implementing institutional controls in the form of environment
easements, deed restrictions, or zoning. The tribes are concerned with this type of action,
it allows industry to pollute as long as they have the financial means to purchase the land
they contaminate and is contrary to the fundamental beliefs of Native Americans.
Institutional controls offer no permanent long-term solution to controlling pollution
sources. This type of option, in addition to source control, would offer added assurances
but alone does little to uphold the mandatory threshold criteria of CERCLA; protection of
public health and the environment. Jurisdictional issues have been at the forefront with
regard to environmental regulation at FMC. Historical practice warrants concern; this
entity chose to file for permits and zoning amendments within Bannock County and Power
County while ignoring Tribal policies. With what jurisdiction entity will these easements,
deed restrictions or zoning be filed? Tribal, County, BIA? Should this option be carried
forward the Tribes request these issues be clearly defined by all parties. The tribes assert
and maintain jurisdiction within the reservation boundaries.
The Endangered Species Act and the Migratory Birds Treaty Act should be added to the
ARARs for this site. Migratory birds are affected by off-site migration of contamination.
GROUNDWATER
The ROD proposes a monitoring program to assure the contamination plume does not
increase at the facility. The tribes recognize there is a need to balance the cost of a
remediation option with the benefits afforded from it. However, we do not believe this
option is the best balance of benefits and trade-offs. Contaminated groundwater mixes
with cleanwater prior to discharging to the river, diluting the contamination to an
acceptable level. This does not justify a no treatment option. Given the site history, the
uncertainty surrounding the quantity of contamination in the ground throughout the
facility, the natural attenuation process, and if attenuation of contaminants in the soil will
continue to be bound at the same level all give rise to the need for some type of treatment.
The tribes recognize that without hydraulic head on areas with contamination the driving
force into the aquifer will be reduced. 'Still, the existing waste and contamination must be
addressed. We support the pump and treat option, recognizing that this will not be a
stagnant process; changing technologies or methodologies may allow for other option at a
later date r
CAPPING
The tribes request there be consistency with the RCRA program in the closure of pond
areas at the facility Many of the areas identified for capping through CERCLA are best
guess estimates of the volume of contaminants based on the length of time the facility used
-------
the area. The tribes believe the most conservative measures must be utilized in ail areas
where definitive data is lacking as to the quantity and chemical characteristics of the
waste. RCRA may have more stringent guidelines in closure requirements for hazardous
waste If this is the case, the tribes request these closure requirements be use.
We believe the above issues must be addressed to adequately protect public health and the
environment. Although some comments may appear negative, the intent is to ensure all
environmental contamination is addressed.
-------
Qualitative Assessment of the Effect of Recent Air Monitoring Results on the findings of
the Baseline Human Health Risk Assessment for the Eastern Michaud Flats Superfund
Site.
Recent air monitoring results for October 1996 through May 1997 have revealed generally higher
levels of airborne paniculate matter immediately downwind from the EMF site than were found
during the period from October 1993 through September 1994 that was used as the basis of the
risk estimates for the air pathway in the Baseline Human Health Risk Assessment (BHHRA) for
the site. This brief report examines the effect these higher airborne paniculate levels would have
on the results and conclusions of the risk assessment.
Quantitative estimates of the risks posed by airborne contaminants associated with the EMF site
were based on the actual concentrations of chemicals and radionuclides measured in airborne
paniculate matter srruJler than 10 u in size (PM|0) - panicles small enough to penetrate the lungs
and deposit there. The recent air monitoring results provide information on the total mass of
airborne PM10 but not on the chemical and radiological composition of these panicles. Therefore
it is not possible to calculate quantitative risk estimates directly from this recent data in the same
way the original risk estimates were obtained. However, the potential risks associated with the
higher levels of paniculate matter can be approximated by simply scaling the risk estimates using
the total PM|0 concentrations measured during the two periods if the composition of the panicles
during those periods is assumed to be the same. Normally this would be a reasonable
assumption, however the change in the source and composition of the ore being processed by the
FMC facility between these two periods probably resulted in greater differences in the
composition of the paniculate matter released by that facility during these periods than would
otherwise be expected. This and other factors that limit the accuracy and reliability of this
simple scaling approach are discussed below.
During the 1993-94 air monitoring program the quantity and composition of airborne paniculate
matter was measured at seven locations in the vicinity of the EMF site (see Figure 3-3 of the
BHHRA). One of these locations, Station 2, was located between the northern boundary of the
FMC fenceline and Highway 30 just west of the boundary between the FMC and Simplot
facilities. During the 1996-97 air monitoring program the total mass of airborne paniculate
matter (Total Suspended Particulates, or TSP) was measured at three locations, two locations
immediately downwind of the EMF facilities near the former Station 2 location, and one at a
nominally upwind location along Michaud Creek near the former Station 5 location. The
primary EPA monitoring station (designated "Primary") for the 1996-97 period was located
several hundred feet east of the 1993-94 Station 2 location; the secpnd downwind station,
established by the Shoshone-Bannock tribes (designated "Sho-Banv), was also located east of the
former Station 2 location. The mass of paniculate matter in two smaller size fractions, PM,0 and
PM: 5, also was measured at the Primary EPA station. A summary of the data available as of this
-------
writing is provided in Table 1. The available PM,0 and PM2 5 (PM fine) data are shown
graphically in the attached figure.
As noted above, the quantitative risk estimates in the BHHRA were based on the concentrations
of chemicals and radionuclides in the PM,0 fraction. Therefore, only the PM,0 measurements
made at Station 7 and the Primary EPA station are relevant to the quantitative risk estimates and
are reasonably comparable in terms of their geographical locations. The average PM10
concentration measured at Station 2 from October 1993 through September 1994 was 55.75
ug/mj, while that measured at the Primary EPA station from October 1996 through May 1997 .
was 77.5 ug/m3, approximately a 39% increase. If the 1996-97 risks from airborne paniculate
matter are approximated, as discussed above, by simply scaling the 1993-94 risk estimates using
the average PM,0 concentrations measured during these periods, the estimated 1996-97 risks at
the Primary EPA monitoring station would be 39% higher than the 1993-94 risks at Station 2. In
the BHHRA, the chemical and radionuclide concentrations in the PM,0 fraction of airborne
particles measured at Station 2 were used to estimate air pathway risks for workers at the FMC
and Simplot facilities (BHHRA Tables 5-5, 5-6, 5-8, and 5-9) and the hypothetical risks to future
residents that might live in the immediate vicinity of the Station 2 location (BHHRA Tables K-
19 and K.-20). In order to estimate the approximate 1996-97 risks for these groups, the 1993-94
"Estimated Cancer Risks" should be multiplied by 1.39. The appropriate "Background Cancer
Risks" should then by subtracted to obtain the approximate 1996-97 "Incremental Cancer Risks".
Site related factors, like the number of furnaces operating, would not affect background airborne
paniculate levels or risks, so the 1993-94 "Background Cancer Risks" can be used in this simple
approach. A brief review of the 1993-94 risk estimates indicates that all of the estimates for site
workers and hypothetical future residents fell in a range generally considered acceptable by EPA
and that none of the Incremental (i.e.: site related) risk estimates would increase to values that
would generally indicate a need for remedial measures as a result of the higher airborne
paniculate concentrations observed during the 1996-97 air monitoring program. This finding
relates only to risks from specific airborne chemical and radiological contaminants, not to the
total PM,0 levels measured, which exceeded applicable standards on a number of occasions.
Uncertainties '
One of the key assumptions inherent in the scaling approach to estimating the air pathway risks
during the 1996-97 monitoring period is that the chemical and radiological composition of the
airborne paniculate matter was essentially the same during the 1993-94 and 1996-97 monitoring
periods. If the source of the ore being processed at the facilities and the facility processes
themselves had remained the same during these periods, it would probably be safe to assume that
the composition of the paniculate matter released from the facilities during those periods also
was essentially the same. However, this was not the case. FMC changed the source of the ore
processed it its facility between the two monitoring periods. The new ore supply is naturally
higher in radionuclides than the old supply and there may be differences in the concentrations of
-------
some of the chemical constituents of the ore as well. All of the contaminants released to the
environment by the EMF facilities are believed to originate as natural constituents of the ore
processed by the facilities. Therefore a change in the composition of the ore being processed can
be expected to result in a corresponding change in the composition of the paniculate matter
released by the facilities. In this case, the higher levels of radionuclides in the ore will likely
have resulted in higher radionuclide concentrations in the paniculate matter released by the FMC
facility and correspondingly higher radiological cancer risks. Therefore, the radiological cancer
risks for the 1996-97 monitoring period are probably somewhat higher than the simple scaling
approach indicates.
A number of comments were received by EPA regarding the 1993-94 air monitoring program
that raised concerns that the results obtained during the 1993-94 monitoring period were not
representative of the long-term air quality in the vicinity of the EMF site. The main reasons
expressed for these concerns were that only 3 of the 4 furnaces at the FMC facility were in
operation during much of the 1993-94 monitoring period and that no extended periods of air
stagnation, like those that have occurred in the area in the past, occurred during that period. Part
of the reason for conducting additional air monitoring around the site was to collect additional
data that might be more representative of the long-term air quality in the area. The fact that
higher airborne paniculate levels were measured during the 1996-97 monitoring period suggests
that the concerns about the 1993-94 data may have been justified. Higher rates of paniculate
emissions from the facilities and less favorable meteorological conditions may indeed have
contributed to the higher airborne paniculate levels measured during the 1996-97 monitoring
period, but there also were other factors that could have contributed to the differences in the
results that should not be overlooked.
These factors include the following:
1. The locations of Station 2 in 1993-94 and EPA's Primary monitoring station in 1996-97
were close to one another but were not exactly the same. As the differences between the
results obtained at the Primary EPA station and the Sho-Ban station illustrate, small
differences in monitoring locations, especially when they are close to an array of point
and small area sources like at the EMF site, can lead to noticeable differences in the
observations obtained.
2. A fourth furnace was operating at the FMC facility during most of the 1996-97
monitoring period that was not operating for much of the 1993-94 period. This could
result not only in an increase in the total emissions during the latter period, but also in
emissions coming from different point sources (i.e.: the furnace flare and pressure relief
valve for the fourth furnace) that were not active during much of the 1993-94 monitoring
period. The difference in the locations of these additional sources relative to the
monitoring locations could have contributed to the differences in the results obtained.
3. Two different air sampler models, manufactured by different firms, are approved by EPA
-------
for use in measuring airborne paniculate matter concentrations. Results obtained using
either model are considered acceptable and equivalent by EPA for regulatory purposes,
however most air monitoring practioners recognize that the Anderson Sampler typically
gives results slightly lower than those given by the Wedding Sampler. Anderson
Samplers were used in the 1993-94 program whereas Wedding Samplers were used in the
1996-97 program. The small difference in the typical performance of the two sampler
models may have contributed to the difference in the results obtained during the two
monitoring periods.
4. There are seasonal differences in meteorological conditions in the Pocatello area that
contribute to characteristic seasonal differences in the levels of airborne paniculate
matter, with levels typically being higher in the fall and winter than in the other seasons.
Paniculate matter measurements are available for a full year for the 1993-94 monitoring
period, however results are only available for October through May for the 1996-97
period as of this writing. The present lack of results for the historically lower
concentration period of June through September of 1997 means that the seasons with
historically lower PM concentrations are currently under represented in the 1996-97
results. This also could contribute to the differences observed between the 1993-94 and
1996-97 results.
-------
Table 1
SUMMARY OF AIR MONITORING RESULTS FOR PARTICULATE MATTER
OCTOBER 1996 THROUGH JUNE 1997
EASTERN MICHAUD FLATS SITE.
Location
Primary
Sample
Type
TSP
Primary IPM10
Primary IPM-Fine
Sho-Ban
Background
TSP
TSP
Sample
Count
POCATELLO. IDAHO
Concentration (ug/m3)
Minimum
1661 8.3999996
74
74
165
165
Average
Maximum
84.9 1 419.70001
2.5 1 77.5 1 293.39999
Standard
Deviation
61. 1|
53.51
0.9! 46.8 1 231.71 40.7!
7.8000002 1 57.3
Oi 17.6
441.799991 59.01
245.5
24.0
-------
Date Primary -P Primary - P Prim-TSP ShBn-TSP Bkgd-TSP
10/07/96
10/08/96
10/09/96
10/10/96
10/11/96
10/12/96
10/13/96
10/14/96
10/15/96
10/16/96
10/17/96
10/18/96
10/19/96
10/20/96
10/21/96
10/22/96
10/23/96
10/24/96
10/26/96
10/27/96
10/28/96
10/29/96
10/30/96
10/31/96
11/02/96
11/05/96
11/06/96
11/07/96
11/08/96
11/09/96
11/10/96
11/11/96
11/12/96
11/13/96
11/14/96
11/15/96
11/16/96
11/17/96
11/18/96
11/19/96
11/20/96
11/21/96
11/22/96
11/23/96
11/24/96
11/25/96
11/26/96
11/27/96
11/28/96
11/29/96
11/30/96
12/01/96
52.200001
26
14.4
65400002
68.599998
137.2
59.700001
32.400002
28.700001
84.599998
32.099998
17.5
56
11.4
39.200001
28.1
35.200001
91.900002
50
39.299999
133.8
116.9
204.8
61.900002
39.5
57.400002
126.8
58.200001
40.400002
105.8
25.1
51.200001
64.900002
82.699997
119.4
85.699997
165.2
127.1
140.5
98.900002
57.900002
198.60001
72.199997
184.2
39.299999
67.900002
121.8
200.39999
96.699997
228.5
8.3999996
36.299999
17.9
13.5
86.699997
114.2
141.89999
133.2
40.700001
41.5
55.900002
62.900002
124
43
42.900002
90.5
123.7
276.79999
419.70001
22.1
54.5
41.200001
51.5
122.6
60.099998
65.599998
52.5
109.3
54.799999
58.700001
86.699997
104.2
117.9
83.400002
59.700001
72.5
35.5
56.299999
193.3
17.6
39.599998
36.299999
73.599998
63.5
16.1
14.2
21.700001
37.200001
46.5
55.599998
48
57.200001
69.400002
65.800003
12.2
9.8999996
65.699997
245.3
84.5
135
11
54.700001
46.299999
9.8000002
53
20.9
9
30.6
163.2
7.8000002
71 199997
115
27.1
56.400002
29.6
34.799999
16.700001
57.099998
17.6
7.4000001
3.5999999
6.8000002
5.3000002
14.'!
20.6
62.700001
4.5
15
23.799999
5.0999999
4.0999999
9
2.0999999
43
53.5
78.599998
107.4
61.400002
3.8
2.5999999
1.1
2.5
1
4.5
1.3
44.900002
2.3
2
4.5999999
1.3
1.4
0.1
7.5
0.6
60999999
-------
12/02/96
12/03/96
12/04/96
12/05/96
12/06/96
12/07/96
12/08/96
12/09/96
12/10/96
12/11/96
12/12796
12/13/96
12/14/96
12/15/96
12/16/96
12/17/96
12/18/96
12/19/96
12/20/96
12/21/96
12/22/96
12/23/96
12/24/96
12/25/96
12/26/96
12/27/96
12/28/96
12/29/96
12/30/96
12/31/96
01/01/97
01/07/97
01/10/97
01/12/97
01/13/97
01/16/97
01/19/97
01/22/97
01/25/97
01/26/97
01/28/97
01/30/97
02/06/97
02/09/97
02/11/97
02/12/97
02/18/97
02/21/97
02/24/97
02/27/97
03/02/97
03/05/97
03/08/97
46.
57.
57.
42.
88.
900002
93.5
299999
799999
299999
0.9
900002
20.5
231.7
70.099998
33
32
52
197.8
22
13
18.4
26.6
.400002
114.1
10.8
10.7
15.5
25.5
.900002
.799999
19.1
6.3000002
69.
68.
15.5
599998
400002
22.799999
67.300003
128.89999
72.599998
91.300003
66.19JI997
2.5
132.60001
58.799999
293.39999
92.900002
246.89999
39.900002
35.299999
28.4
35.200001
42
154.10001
14.1
10.9
25.9
37.400002
71.199997
86.900002
35.299999
15.8
27.799999
149.89999
107.8
45.599998
168.39999
89.900002
128.89999
88.599998
73
75
184.3
132.10001
83.900002
72.400002
39.900002
63.799999
218.8
47.5
14.3
23.5
19.5
155.89999
45.200001
30.6
62.200001
173.60001
174.3
316.79999
236.10001
109.7
290.39999
187.10001
186
148.8
85.900002
25.4
70.699997
128.3
199.10001
64
32.5
57.099998
124.6
198.8
208.10001
40.700001
27.9
38.200001
8.1000004
52.700001
15.5
21.299999
19.1
• 17.9
21.4
19.700001
35.799999
56.299999
110.6
47.599998
16.1
282.10001
292.60001
441.79999
35.299999
t
40.700001
12.5
8.3999996
9.3000002
8.1999998
0.6
2.5
3.7
2.5999999
2.4000001
1
5.1999998
12.5
0.5
1.2
11.9
23.5
6.3000002
31.5
18.4
5.3000002
14.9
7.8000002
2.2
0.9
0.1
0
0.3
0.3
3
1.9
245.5
21.6
12.7
-------
03/1 1/97
03/14/97
03/17/97
03/20/97
03/21/97
03/22/97
03/23/97
03/24/97
03/26/97
03/27/97
03/28/97
03/29/97
03/30/97
03/31/97
04/01/97
04/02/97
04/03/97
04/04/97
04/05/97
04/06/97
04/07/97
04/08/97
04/09/97
04/10/97
04/11/97
04/12/97
04/13/97
04/14/97
04/15/97
04/16/97
04/17/97
04/18/97
04/19/97
04/21/97
04/22/97
04/23/97
04/24/97
04/25/97
04/26/97
04/27/97
04/28/97
04/29/97
04/30/97
05/01/97
05/02/97
05/03/97
05/04/97
05/05/97
05/06/97
05/07/97
05/08/97
05/10/97
05/11/97
150.8
5.5
69.900002
29.299999
34.900002
70.199997
22.799999
18.299999
21.4
65.599998
11.3
48.200001
41.299999
27.799999
32.700001
36
16.6
24
70.699997
28.299999
187.2
14.8
107.6
69.199997
62.400002
146.10001
36.099998
46.099998
61.299999
120.9
20.700001
94.099998
91.5
64.699997
70.699997
60
35.099998
36.799999
112.3
51.5
69.699997
83.300003
43.099998
85.300003
54.5
165.89999
109.2
72.900002
39.900002
96.300003
136.39999
53.700001
12.7
88.099998
77.5
20.299999
67.300003
111.7
32.200001
20.200001
35.5
23.6
103.5
90.099998
70.599998
65.400002
72
58.900002
70.199997
65.099998
59.799999
98.800003
61.700001
I
45.099998
73.099998
51.700001
53.700001
28.700001
30.200001
41.900002
107.9
45.200001
60.700001
71.599998
34.299999
53.400002
38.400002
46.5
18.6
45
42.400002
40.299999
37.400002
44.599998
26
234.3
113.2
19.799999
10.7
58.599998
55.799999
25
90
45.700001
33.599998
21.299999
35.700001
27.200001
85.300003
54.599998
30.700001
98.199997
75.800003
37.400002
20.200001
33.900002
23.9
14.4
25.5
52.700001
13.7
11.6
10.4
7.8000002
65.400002
114.4
50.400002
41.099998
39.200001
26.799999
29
76.400002
40.5
15.3
7.1999998
29.200001
14.4
23.9
25.700001
12
14.3
3.9000001
10.1
15.9
10.1
16.9
14.3
38.200001
19.5
11.2
12.6
32.299999
29.9
28.299999
19.700001
10.7
15.7
10.5
23.799999
56.599998
7.4000001
8.1999998
10.1
5.4000001
3.7
3.2
8.6000004
16.200001
6.5
4.4000001
3.9000001
6.3000002
4.8000002
18
13.6
27.5
16.799999
16.6
23.200001
28.4
28.799999
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05/12/97
05/13/97
05/14/97
05/15/97
05/16/97
05/17/97
05/18/97
05/19/97
05/20/97
05/22/97
05/23/97
05/24/97
05/25/97
05/26/97
05/27/97
05/28/97
05/29/97
05/30/97
05/31/97
06/02/97
06/03/97
06/04/97
06/05/97
06/06/97
06/08/97
06/09/97
06/10/97
06/11/97
06/12/97
06/13/97
06/14/97
06/15/97
06/16/97
06/17/97
06/18/97
06/19/97
06/20/97
06/21/97
06/22/97
06/23/97
06/24/97
06/25/97
06/26/97
06/27/97
06/28/97
06/29/97
100.2
60.900002 113.3 112.9
77.5
101.6
48.200001 69.800003 81.099998
104.4
43.400002
40.200001 82 94.900002
65
15.8 43.200001 48.799999
53.400002
23.4
38 69 63.299999
83.400002
52.799999
50.200001 89.199997
25.1
29.1
87.199997 151.60001 151.5
25.1 62.799999 87.300003
68.199997
38.799999
63.799999
34.200001
19.9
71.300003
103.1
48.200001
23.200001
51.200001
40.200001
64
45.900002
71.099998
113.6
144.5
74.900002
63.200001
27.1
24.4
30.700001
81.300003
85.099998
95.099998
65.099998
46.5
45.299999
30.200001
39.599998
37
48.299999
24.799999
61
72.800003
65.199997
33.900002
20.700001
23.200001
54.299999
25.1
16.5
36.599998
21.799999
167.3
27.799999
20.5
16.700001
12.5
21.200001
23.5
55.299999
25.4
19.799999
48.400002
18.4
28.200001
48.400002
24.9
32.299999
49.200001
43.099998
32.599998
25.1
28.799999
33.-799999
86.199997
61
100.1
76.199997
31.799999
27.5
24299999
24 200001
36
28.700001
16
21.299999
21.200001
18.299999
16.299999
10.6
46999998
6.1999998
14.8
7
16.200001
22.799999
13.7
12.4
9.8999996
7.8000002
15.6
9.3000002
11.6
18.1
11.4
14
17.1
10.3
15.4
15.7
12.2
24.700001
19.299999
15.3
10.1
29.1
45.599998
52.799999
34.5
31.299999
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APPENDIX C
STATE OF IDAHO CONCURRENCE WITH REMEDY
RECORD OF DECISION
FOR
FINAL REMEDIAL ACTION
EASTERN MICHAUD FLATS SUPERFUND SITE
POCATELLO, IDAHO
C-l
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STATE OF IDAHO
DIVISION OF
ENVIRONMENTAL QUALITY
1410 North Hilton, Boise, ID 83706-1255, (208) 373-OM2 Philip E. Ban. Governor
May 19, 1998
Chuck Clarke, Regional Administrator
U.S. Environmental Protection Agency
Region X
1200 Sixth Ave.
Seattle, WA 98101
Subject: State of Idaho Concurrence on the Eastern Michaud Flats Record of Decision
This letter is to notify the Environmental Protection Agency (EPA) that the State of Idaho
concurs with the Record of Decision (ROD) for the East Michaud Flats Superfund site in
Pocatello, Idaho.
I am pleased with the work by our respective staff which has lead to this ROD concurrence.
The Division of Environmental Quality (DEQ) participated in review of the Remedial
Investigation and Feasibility Study Report, including the risk assessment and preceding
work plans, technical documents and data. DEQ participated in the evaluation of cleanup
alternatives in preparation of the EPA proposed plan, and participated in public meetings
held during the comment period. Subsequent to the close of the public comment period,
DEQ provided review and comment on draft versions of the EPA Record of Decision and
responsiveness summary. We intend to continue our involvement with EPA toward
implementation of this ROD.
Sincerely,
Wallace N. Cory,
Administrator
Division of Environmental Quality
WNC:DN:mp
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DOCK TRIBES
fHOiHOOi
FORT HALL BUSINESS COUNCIL
P. 0. BOX 306
FORT HALL. IDAHO 83203
June 3, 1998
'8
)RT HALL INDIAN RESERVATION
; Tril,?s. The Tribes support the following elements of the proposed plan: monitoring of
fluoride emissions off-site, monitoring grou'nd wa;ei to insure no increases in the
contamination, and capping of historical pond areas. However, we believe theso: measures
should accompany additional action such as treatment of groundwater and source control of
The Fort Hall Reservation is the homeland of the Tribes as guaranteed by the Fort
Pruj.jei Treaty signed in 1868. Accordingly, the reservation lands are trust resources to be
;)iu'ii!cit".! i,-y the trustee EFA. In light of this, the Reservation is substantially different from thi
(•-•>.''.,• C'f:-iusoi\-;mori privoiely held lamJs and requires extra protection based on federal law.
n is '.hi-;fcfiji-j incumbent upon the EPA. pursuant to the EPA Indian Policy, its general trust
:--.i;MiO".SMip with a triboi i|i>vn:nmeiil and the Environmental Justice Policy, to afford Kuoh
l^otijciioiis to :\\& Sh:)'-.iiciK>-3:jrtnfic:: Tribes and theii lands. The ROD in its final suite tail-; to
r-iuvi:!.: such protection. Instead, the treaty homelands are treated as any other private land in
IMP MiUi.-nid Flats area. In ad-.iition, there is not sufficient protection for the human health of
*:.•_• R'-.-;€.'r ,;i:iu:: |)i:|;u:;:'jo;i. \Ve certain!-/ would agroe t!ie overall reriiedy and actions taken !;•/
.'.i: U S. ^iv.-.loniiit ju.'il PrctcCtiuii Agency ore well intended. Mowev^r, we must once jyain i'.: .-
:•.'•.n-,..ii"j:irr .T.ct' v.iih the Final ROD. Ttns letter .^els forth our reasons for non-concurrence.
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Overall, we do not believe the remedial actions sufficiently protect human health and
the environment of residents and members of the Shoshone-Bannock Tribes. The remedy
assumes continued operation of the plants by FMC and Simplot in compliance with air Federal
and State environmental requirements. The FMC plant is not in compliance with all Federal
environmental requirements; specifically, the Resource Conservation and Recovery Act, and the
Clean Air Act. In addition, toxic emissions through the air pathway historically and currently
have no federal regulatory requirements and will not until a Federal and Tribal Implementation
Plan is promulgated and a Federal Operating Permit is issued. Moreover, it is uncertain if toxic
air emissions from the FMC facility will be regulated within this scheme. The National
Pollution Discharge Elimination System permit FMC holds for discharge to the Portneuf River is
a decade old and provides no contaminant limits on heavy metals, some of which were found
elevated in the Portneuf River sediments. Groundwater contamination from this site is entering
the Portneuf River and flowing into the Fort Hall Bottoms area. The Portneuf River is a gaining
stream which dilutes the contaminants. However, attaining acceptable contaminant levels as a
result of dilution, and at the point of dilution is not an acceptable remedy for the Tribes.
Our non-concurrence is also based on the inadequacy of studies, the failure to review
existing health studies, and the lack of scientific investigation by the EPA. The EPA undertook
a baseline human health and ecological risk assessment of the Michaud Flats area as part of
the CERCLA investigation and the results of these assessments directed the cleanup remedy.
A complete emission inventory was not conducted and the complete array of toxic emissions
were not characterized or factored into the assessment, specifically, phosphorus pentoxide,
speciation of radionuclides, hydrogen cyanide, and phosphine. The Tribes requested EPA to
evaluate the FMC mortality study and epidemiological study of FMC workers. No action was
taken on the Tribes' recommendation. Airborne contaminants from the plants at this Site have
resulted in elevated concentrations of cadmium, fluoride, radionuclides, and zinc in surface
soils. The Ecological Risk Assessment notes that the potential for impacts is expected to
increase over time with continued air deposition. While monitoring for contaminants will
provide information it does not provide a permanent solution for, or prevention of future
contamination.
Neither the Human Health or Ecological Risk Assessments considered the impacts on
cultural resources of the Tribe:;. In an October 1997 meeting EPA agreed to consider native
uses of plants in the human health risk assessment. Subsequently the Tribes were notified by
EPA that a comparison to the Fruit and vegetable study conducted in the human health risk
assessment would be the benchmark for consideration of health affects from cultural uses of
native plants. The Tribes did not believe this comparison, consumption of fruits and vegetables
by Non-Native Americans would be representative of the actual cultural uses of plants and
animals, and the risks posed from those uses. Therefore, data on the cultural plants and uses
was not provided to the EPA. While the ecological risk assessment identified risks to individual
species, risks to the ecological community population was the departure point for determining
action. Many Tribal members on the Fort Hall Reservation practice subsistence hunting and
fishing and may be at greater risk for exposure to contaminants through ingestion of plants and
animals containing contaminants.
Institutional controls within the boundaries of the Fort Hall Indian Reservation does not
afford protection from future contamination of our land. Additionally, we assert our jurisdiction
and sovereignty rights within the boundaries of the Reservation and would require any controls
to comply with Tribal laws and policies.
-------
Furthermore, we do not concur due to the inconsistency between EPA's RCRA and
.'ERCLA programs at the FMC facility regarding hazardous waste. Although EPA RCRA and
!ERCLA programs have a memorandum of understanding regarding coordination of remedial
ctivities at this site, environmental requirements imposed within the facility by these
rograms. regarding the same type of hazardous waste are inconsistent between the programs.
he Tribes agree with the need to cap the old hazardous waste pond areas but believe there
hould be consistency on the requirements imposed.
In conclusion, our position with regard to the CERCLA remedial action on the Fort Hall
teservation has always been to insure that all environmental contamination is adequately
iddressed. As we have explained to EPA we must preserve our Reservation for future
lenerations. Unfortunately, as presented, the EPA's Record of Decision does not adequately
iddress or provide sufficient protection for present and future generations of the Shoshone-
Jannock Tribes. We respectfully do not concur with the Record of Decision.
Sincerely,
Arnold Appenay. Chairman
Fort Hall Business Council
Tribal Attorney Office
Genevieve Edmo, Land Use Director
Susan Hanson, Program Manager
Kathy Gorospe, Director, AIEO
Stan Speaks, BIA Area Director
Sam Hernandez, BIA
Chuck Clarke, Regional Administrator
Doug Cole, Tribal Liaison
Bill Adams, EPA Project Manager
Jim McCormick, FMC Coordinator
Gov. Phil Batt, State of Idaho
Wally Corey, DEQ
Gordon Brown, Pocatello, DEQ
Preston Sleeger. DOI
Susan Burch, U.S. Fish and Wildlife
Senator Dirk Kempthorne
Senator Larry Craig
Representative Mike Crapo
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APPENDIX D
METHOD USED TO ESTIMATE CONCENTRATIONS OF RADON
IN INDOOR AIR
RECORD OF DECISION
FOR
FINAL REMEDIAL ACTION
EASTERN MICHAUD FLATS SUPERFUND SITE
POCATELLO, IDAHO
D-l
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Method Used to Estimate Radon Concentrations in Indoor Air
Both facilities at the EMF site are currently expected to continue operations for the foreseeable
future; however, there is always a possibility that one or both facilities could cease operations
and that the land could be converted to an alternate use. Because of the industrial nature of the
facilities and the large amount of waste materials stored at the facilities, the likely alternate
future use would be commercial or industrial use. Under such a future use scenario, a worker
employed at the redeveloped site would probably have the greatest potential exposure to site
contaminants. During site redevelopment, new buildings could be constructed in areas of the site
with elevated levels of radionuclides in the soil. Workers using such buildings could be exposed
to elevated levels of radon in indoor air that infiltrated the buildings from the adjacent soil.
Radon-222 concentrations in indoor air resulting from infiltration of vapors from contaminated
soil were estimated using a two-step process. First, the concentration of radon-222 in soil gas
adjacent to the building basement was estimated. The concentration in soil gas then was reduced
using an attenuation factor to estimate the concentration of radon-222 in indoor air.
Neither radon-222 nor its parent, radium-226, was measured in site soils; therefore, the concen-
trations had to be estimated. First, the concentration of radium-226 was derived from the
measured gross alpha activity using an extrapolative method recommended by EPA; 25% of the
gross alpha activity was attributed to radium-226. The estimated radium-226 soil concentration
was then multiplied by an emanation coefficient to obtain the concentration of radon-222 present
in soil gas. Because radon-222 has a half-life of 3.8 days, the emanation factor accounts for the
radioactive decay of some of the radon before it can escape from the soil. An emanation
coefficient of 25% was used; this value is the average of the emanation coefficients reported for
phosphogypsum (20%) and water treatment sludges (fertilizers) (30%) (USEPA 1993).
Once the concentration of radon-222 in soil gas adjacent to the building basement was deter-
mined, it was multiplied by an attenuation factor, derived using a model developed by Johnson
and Ettinger (Johnson and Ettinger 1991), to obtain the concentration in the air inside the
building. The model predicts an attenuation coefficient (AC) based on the infiltration of
chemical vapors into buildings through cracks and openings in the foundation and on building
ventilation characteristics (see Attachment A for the spreadsheet used to calculate the AC).
i
Johnson and Ettinger present a sample calculation showing the derivation of AC for a typical
residential building. Since the model is being used in this report to estimate indoor radon
concentrations in a hypothetical building that might be constructed on site in the future, the
dimensions and other characteristics of which are unknown, most of the parameter values used in
the sample calculation were retained unless there was a site-specific reason to modify them (see
Attachment A). The effective diffusion coefficient, soil permeability, and the building ventila-
tion rate were changed from values used in the sample calculation as follows:
• The Effective Diffusion Coefficient: The effective diffusion coefficient
presented in the Johnson and Ettinger paper is for benzene and is inappropriate
to use for radon. The radon diffusion coefficient used in the EMF calculations,
3 x 10"" cm /s, is for sand-like material (Cothem and Smith 1987) and was
provided in a memo from Bechtel Environmental, Inc., to the EPA (Bechtel
1995).
D-2
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• Soil Permeability: The value used for soil permeability, 1.0 x 10 , which is
slightly lower than the value used by Johnson and Ettinger, is the average
permeability for fine- to medium-grained sand. The solid materials on the site
range from very fine wind-blown soil (loess) and process wastes to coarse slag
material, and it is not known on what type of material future construction might
take place. The value used is believed to be a reasonable estimate of the average
permeability of the materials at the site. The Johnson and Ettinger model is
particularly sensitive to the value used for soil permeability. In fact, there is
almost a direct correlation between the estimated soil permeability and the
predicted concentration of radon in indoor air.
• Building Ventilation Rate: The default value for the building ventilation rate
provided in Johnson and Ettinger was doubled to 5.8 x 10 cm /s, which
corresponds to a total basement air exchange rate of 1/hr. The default value
which corresponds to a total basement air exchange rate of 0.5/hour is thought
to be appropriate for relatively new residential buildings, but too conservative
for commercial or industrial buildings where more activity likely would occur
(i.e., frequent opening and closing of doors, etc.).
Finally, the indoor air radon concentrations predicted using the outlined approach were com-
pared to the measured values obtained at the Simplot facility in 1990 (Bechtel 1993) as a reality
check. The indoor air radon concentrations obtained starting from the gross alpha activity in
background soil correspond well to the lowest levels measured in Simplofs buildings in 1990
(1.25 vs. 0.2 to 1.8 pCi/l). Likewise, the predicted radon-222 in indoor air corresponding to the
exposure point gross alpha levels in FMC and Simplot soils are only slightly higher than the
maximum concentrations detected in the Simplot buildings (predicted: FMC: 10.5, Simplot: 9.4
vs. maximum measured values of 7.9 and 8.3 pCL/1 - excluding the Frontier Building where ore
samples were stored). Although there is uncertainty in the model calculations because of the
lack of facility-specific data, these comparisons suggest that the model provides a reasonable
estimate of the levels of radon-222 in indoor air to which future site workers might be exposed.
References
Bechtel Environmental, Inc. (Bechtel), 1993, Eastern Michaud Flats RI/FS, Summary of EPA
and Simplot Radon Studies, memo dated November 19, 1993.
, 1995, Eastern Michaud Flats Rl/FS, Radon Emission Estimates, memo dated
February 8, 1995.
Johnson. P.C. and R.A. Ettinger, 1991, Heuristic Model for Predicting the Intrusion Rate of
Contaminant Vapors into Buildings, Environmental Science and Technology, Vol. 25,
No. 8, pages 1445-1452.
Nazaroff, W.W., 1988, Radiation Protection and Dosimetry, 24:199-202.
United States Environmental Protection Agency (USEPA), 1993, Diffuse NORM Wastes: Waste
Characterization and Preliminary Risk Assessment, Draft Volume I, RAE-9232/1-2,
prepared for Office of Radiation and Indoor Air.
D-3
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APPENDIX E
ADMINISTRATIVE RECORD INDEX
RECORD OF DECISION
FOR
FINAL REMEDIAL ACTION
EASTERN MICHAUD FLATS SUPERFUND SITE
POCATELLO, IDAHO
E-l
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