United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
&EPA Superfund
Record of Decision:
EPA/ROD/R10-93/057
December 1992
US DOE Idaho National
Engineering Laboratory
-------
50272.101
.
REPORT DOCUMENTATION 1" REPORT NO. 1 3. Recipient'. Ace_Ion No.
PAGE EPA/ROD/R10-93/057
4. TIU8 and Subtitle 5 Report Date
SUPERFUND RECORD OF DECISION 12/10/92
USDOE Idaho National Engineering Laboratory (Operable &
Unit 4), ID
Sixth Remedial Action
7. Author(.) I. Performing Organization Rept. No.
II. P8rformlng Organization Name and Add- 10 Project T88k/Work Unit No.
11. Contract(C) or Grant(G) No.
(C)
(G)
12. ~ng Organization Name and Add.... 13. Typa of Raport . Period eov,r8d
U.S. Environmental Protection Agency 800/800
401 M Street, S.W.
Washington, D.C. 20460 14.
15. Supplemanlary Nell.
.,
PB94-964611
11. Ab8tract (Umlt: 200 words)
The 1,700 by 1,900 feet USDOE Idaho National Engineering Laboratory (Operable Unit 4)
is part of the 890-square mile U.S. Department of Energy (USDOE) facility located in
Idaho Falls, Idaho. The primary mission of the Idaho National Engineering Lab (INEL)
is nuclear reactor technology development and waste management. Land use in the area
is predominantly industrial with mixed uses (restricted agricultural and recreational
uses). The site, also known as the Test Reactor Area (TRA), contains more than 73
buildings and 56 structures such as tanks, cooling towers, laboratories, offices, and
three high neutron flux nuclear test reactors, of which only one is currently
operational. Approximately 7,700 people are employed at the INEL, with an estimated 600
employed at the TRA. Drinking water for the employees is obtained from production wells
located within the facility. The site is contained within the northeastern portion of
the Eastern Snake River Plain (ESRP), borders a floodplain to the west and north, and
overlies the Snake River Plain Aquifer, which is a sole-source aquifer. The TRA was
established in the early 1950s to operate and test high neutron ,flux nuclear test
reactors. Prior to 1964, most of the chemical and radioactive wastewater generated
during site operations was discharged directly to six wastewater ponds at the TRA. Use
(See Attached Page)
17. Document Analysis L Deacrlptora
Record of Decision - USDOE Idaho National Engineering Laboratory (Operable Unit 4), ID
Sixth Remedial Action
Contaminated Medium: None
Key Contaminants: None
b. Id8ntlfl8rs1Ope~nd8d Tenna
c:. COSATI Fl8lcUGroup
11. Availability Stat-- 19. Security C1a88 (Thl. Report) 21. No. of Page.
None 58
20. Security CIaa. (Thia P~ge) zz. PrIca
None
(Saa ANSI-Z39.18)
s..1nat1UCt1ons OIl R."..
OPTIONAL FORM 272 (4-77)
(f'onnarly NTISo35)
Department of Comman:a
.
-------
EPA/ROD/R10-93/057
USDOE Idaho National Engineering Laboratory (Operable Unit 4), ID
Sixth Remedial Action
Abstract (Continued)
of these ponds has contributed to the formation and contamination of the Perched Water
System. From 1964 until 1982, wastewater was injected directly into the Snake River Plain
Aquifer, which did not contribute to the perched water contamination. Currently, there
are four active disposal units that receive waste effluent generated at the TRA. These
are the warm waste pond, which receives radiologically-contaminated wastewater; the cold
waste pond, which receives primarily reactor cooling water with no radiological activity;
the chemical waste pond, which is used for disposal of wastewater from ion exchange units
and water softeners; and the sanitary waste ponds. Studies of the perched ground water
and the Snake River Plain Aquifer, conducted by DOE,identified low-level contamination by
VOCs, other organics, metals, other inorganics, and radionuclides. Previous 1992 RODs
addressed sediment at the Warm Waste Pond, ordnance and contaminated soil, contaminated
ground water at the Technical Support Facility, and contaminated sediment and sludge in
the evaporation pond, discharge pipe, and waste sump as OUs 5, 23, 2, and 22,
respectively. This ROD addresses the contaminated Perched Water System within the TRA, as
OU4. Other 1993 RODs addresses the Perched Water System, the CFA Motor Pool Pond and Pit
9 of the Subsurface Disposal Area, as OUs 4, 9, and 18 respectively. Because public
access to the TRA is restricted and the Perched Water System is approximately 50 to 150
feet below the ground surface, current public exposure to the perched water is unlikely.
Furthermore, results of human health and ecological risk assessments demonstrate no
unacceptable risk to human health and the environment. As a result, no remedial action is
necessary for the Perched Water System at the TRA; therefore, there are no contaminants of
concern affecting this site.
.
.
The selected remedial action for this site is no .further action, with ground water
monitoring. To support the no remedial action decision, DOE will begin a minimum 10-year
decontamination and decommission period in the year 2007, when operations at the TRA have
ceased; maintain existing institutional controls, including land use restrictions and
property access restrictions; and replacing the existing warm wastewater pond, which is
the major source of contamination in the perched groundwater, with a new lined pond in
1993. Future contact with the Perched Water System also is unlikely because it is
predicted to dissipate within about 7 years of ceasing disposal of wastewater to the ponds
at the TRA according to modeling results. Results of human health and ecological risk
assessments demonstrate no unacceptable risk due to potential future use. There are no
costs provided for this no action remedy.
PERFORMANCE STANDARDS OR GOALS:
Not applicable.
-------
.
RECORD OF DECISION
FOR THE TEST REACTOR AREA PERCHED WATER SYSTEl\1
OPERABLE UNIT 2-12-
AT THE
IDAHO NATIONAL ENGINEERING LABORATORY
",
.
. .
.-
RECEIVED
DEC 1 n 1992
/-
-------
TABLE OF CONTENTS
STATEMENT OF BASIS AND PURPOSE. . . . . . . . . . . . . . . . . . . . . . . . . . .. iv
DESCRIPTION OF THE SELECI'ED REMEDY ......................... iv
.
. .
DECLARATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., v
.
DECISION S~Y . ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., 1
1. 'SITE NAME, LOCATION, AND DESCRIPTION. . . ~ . . . . . . . . . . . . . . . .. 1
2. SITE HISTORY AND ENFORCEMENT ACTIVITIES .................. 2
2.1 Site History. . .. . . . . . .'. .'. . . . . . . . . . . . . . . . . . . . . - . . . . . ., 2
2.2 Current Facility Operations. . . . . . . . . . . . . ~ . . . . . . . . . . . . . . . .. 3.
2.3 Previous Groundwater Investigations. . . . . . . . . .. . . . . . . . . . . . . . .. 4
2.4 Enforcement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .4
3. ffiGHLIGHfS OF COMMUNITY PARTICIPATION. . . . . . . . . . . . . . . . . ., 4
4. SCOPE AND ROLE OF OPERABLE UNIT AND RESPONSE ACTION. . . . . . .. 6
5. SUMMARY OF SITE CHARACTERISTICS. . . .'. . . . . . . . . . . . . . . . . . . ., 7
5.1 Geology and Hydrology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
5.1.1 Surface Water. . . . . . . . . ~ . . . . . . . . . . . . . . . . . . . . . .. 7
5.1.2 Perched Water. . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. 7
5.1.3 Snake River Plain Aquifer ~ . . . . . . . . . . . . . . . . . . . . . . . .. 8
5.2 Nature and Extent of Contamination. . . . . . . . . . . . . . . . . . . . . . . .. 8
5.2.1 Shallow Perched Zone. . . . . . . . . . . . . . . . . . . . . . . . . . .. 9
5.2.2 Deep Perched Groundwater Zone. . . . . . . . . . . . . . . . ~ . . .. 10
5.2.3 Snake'River Plain Aquifer. . .. . . . . . . . . . . . . . . . . . . . . . . 10
5.2. Groundwater Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6. SUMMARY OF. SITE RISKS .......:.................'......'''.' 12
'. 6.1 Human Health Risk Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1.1 Identification of Contaminants of Concern . . . . . . .' . . . . . . . .. 12
6.1.2 Exposure Assessment. . . . . . . .'. . .'. . . . . . . . . . . . . !" . . . . 13
6.1.3 Toxicity Assessment. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . 15
6.1.4 Risk Characterization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1.5 Uncertainty. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.2 Ecological Risk Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.2.1 Exposure Assessment. . . ..' . . ~ . . . . ... . . . . . . . . . . . . . . . 19
6.2.2 Risk Characterization. . . . . . .': . . . . . . . . . . . . . . . . . . .'. . 20
"
. .
-------
7. DESCRIPTION OF NO ACTION DECISION. . . . . . . . . . . . . . . . . . . . . . . . 20
8. EXPLANATION OF SIGNIFICANT CHANGES. . . . . . . . . . . . . . . . . . . . . . 21
REFEREN"CES ............................................. 22
w
APPENDICES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .' A-I
Appendix A Public Comment/Response Index. . . . . . . . . . . . . . . . . .. A-I
FIGlJRES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 1. Location of the Test Reactor Area . . . . . . . . . . . . . . . . . . . . . 23
Figure 2. Test Reactor Area and surrounding area . . . . . . . . . . . . . . . . . 24
Figure 3. Generalized cross section showing a TRA waste water disposal
pond and the Perched Water System under TRA. ...... ~ . . .. 25
Configuration of the deep perched ground water at TRA, March
21, 1991 .................................... 25
Locations of deep perched monitoring wells. .............. 26
Shallow perched ground water monitoring locations. ......... 26
Locations of Snili River Plain Aquifer wells. ............. 27
Maximum modeled chromium concentrations in the Snake River
Plain Aquifer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Maximum modeled tritium concentrations in the Snake River Plain
Aquifer. .................................... 28
Figure 10. Maximum modeled cadmium concentrations in the Snake River
Plain Aquifer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
TABLES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 1. Tot2l and daily process water discharged to the Test Reactor Area
pond system... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Concentration ranges and detection frequency in the shallow
perched zone. ................................. 31
Concentration ranges and.detection frequency in the deep perched
zone. ...................................... 35
Federal drinldng water standards and background concentrations
for inorganics, organics, and radionuclides. ........ . . . . . .. 37
Perched Warer System contaminants of concern and deep perched
zone mean concentrations. ......................... 40
Average concentrations of contaminants used for risk asse8S111ent
and in the Perched Warer System predicted by computer mOdel. .. 41
Summary of nonradiological carcinogenic. risk in year 2115. . . . .. 42
Summary of radiological carcinogenic risk in year 2115. . . . . . .. 43
Snmmary of noncarcinogenic hazard indices (child) in year
2115. .................'...................... 44
Figure 4
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
.
Table 7.
Table 8.
Table 9.
-------
Table 11.
Table 12.
Table 13.
Summary of noncarcinogenic hazard indices (adult) in YeaI
2115. ...................................... 45
Summary of 30-year rolling average concentrations. . . . . . . . . . . 46
NeaI-tenn excess lifetime cancer risks from tritium exposure. . . .. 47
Near-tenn hazard quotients for cadmium and total chromium. . . .. 48
Table 10.
RESPONSIVENE5S SUMMARY. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 49
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Background on Community Involvement. . . . . . . . . . . . . . . . . . . . . . . . . . 49
Summary of Comments Received During Public Comment Period. . . . . . . . . . 50 ,
.. .
~
-------
DECLARATION OF THE RECORD OF DECISION
FOR THE TEST REACTOR AREA PERCHED WATER SYSTEM
AT THE
IDAHO NATIONAL ENGINEERING LABORATORY
.
SITE NAME AND LOCATION
Perched Water System
Test Reactor Area
Idaho National Engineering Laboratory
.STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected final remedy (no remedial action with monitoring)
for the Test Reactor Area Perched Water System, Operable Unit 2-12 at the Idaho National
Engineering LaboIatory. The remedy was selected in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act, as amended by the Superfund
... Amendments and Reauthorization Act, and to the extent practicable, the National Oil and
Hazardous Substances Pollution Contingency Plan. This decision is based on the AdministIative
Record for the site. . .
The lead agency for this decision is the U.S. Department of Energy. The Environmental
Protection Agency approves of this decision and, along with the State of Idaho Department of
. Health and Welfare, 'has participated in the scoping of the site investigations and in the
evaluation of remedial investigation data. The State of Idaho concurs with the selected remedy.
DESCRIPTION OF THE SELECTED REMEDY
.
It has ,been detennined that no remedial action is necessary for the Perched Warer System at the
Test Reactor Area to ensure protection of human health and the environment. This decision is
based on the results of the human health and ecological risk assessmen~, which determined that
conditions at the site pose no up~r.ceptable risks to human health or the environment for expected
current or future use of the Snake River Plain Aquifer beneath the Perched Water System at the
Test Reactor Area.
-------
Components and assumptions for the No Remedial Action decision are:
.
Groundwater monitoring will be conducted to verify that contaminant
concentration trends follow those predicted by a groundwater computer model.
Within forty-five days of signature of this Record of Decision, a monitoring plan
will be developed by the U.S. Department of Energy and submitted to the U.S.
Environmental Protection Agency and the Idaho Department of Health and
Welfare as a primary document pursuant to the Idaho National Engineering
. Laboratory Federal Facility Agreement and Consent Order.
.
Operations at the Test Reactor Area will.continue at least through the year 2007,
followed by a minimum estimated lo-year decontamination and decommissioning
period. Existing institutional controls, which include land use and property
access restrictions, will continue to be maintained during this period.
.
The existing warm waste pond, which is the major source of contamination in the
perched groundwater, will be replaced by a new lined pond in 1993. The
Remedial Investigation incorporated the assumption that the existing warm waste
pond would be rep1a.ced by the new lined pond.
DECLARATION
It has been determined that no remedial action is necessary to ensure protection of human health
and the environment. Because this decision will result in hazardous substances remaining on the
site above health-based levels, a statutory review of this decision will be conducted by the
Department of Energy, the Environmental PrOtection Agency, and the Idaho Department of
Health and Welfare if any of the assumptions used to arrive at the No Remedial Action decision
change, but no-later than three years to ensure that adequate protection of human health and the
environment continues to be provided. This review will evaluate the assumptions used to arrive
at the No Remedial Action decision.
"
.. .
.-
-------
Signature sheet for the foregoing Operable Unit 2-12 Perched Water System at the Test Reactor Area at the I
-------
Signature sheet for the foregoing Operable Unit 2-12 Perched W~ System at the Test Reactor
Area at the Idaho National Engineering Laboratory Record of Decision between the United
States Department of Energy and the United States Environmental protection Agency, with
concurrence by the Idaho Department of Health and Welfare.
. .
~ ~ŁUL~
Dana Rasmussen
Regional Administrator, Region 10
Environmental Protection Agency
DEC 1 {} 1992
Date
.
.
-------
Signature sheet for the foregoing Operable Unit 2-12 Perched Warer System at the Test Reactor
Area at the Idaho National Engineering Laboratory Record of Decision between the United
States Department of Energy and the United States Environmental Protection Agency, with
concurrence by the Idaho Department of Health and Welfare.
, .
~f!~
. chard Donovan ~
Director.
Idaho Department of Health and Welfare
12~5/qz
Date
. .
.'
-------
RECORD OF DECISION FOR THE PERCHJID WATER SYSTEM
AT THE TEST REACTOR AREA, OPERABLE UNIT 2-12,
AT THE IDAHO NATIONAL ENGINEERING LABORATORY
DECISION SUMMARY
Introduction
The Idaho National Engineering Laboratory (INEL) was proposed for listing on the
National Priority List (NPL) July 14, 1989 [54 Federal Register (FR) 29820]. The listing was
proposed by the Environmental Protection Agency (EP A) under the authorities granted EP A by
the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of
1980 as amended by the Superfund Amendments and Reauthorization Act of 1986. The final
rule that listed the INEL on the NPL was published November 21, 1989, in 54 FR 44184.
In accordance with the CERCLA, Executive Order 12580 (Superfund Implementation) and
the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) (EPA 1990), the
U.S. Department of Energy (DOE) perfonned a Remedial Investigation for the Perched Water
System. The Remedial Investigation characterized the nature and extent of contamination in the
Perched Water System. A Human Health Risk Assessment and an Ecological Risk Assessment
were conducted to evaluate potential effects of the Perched Water Systein on human health and
the environment.
1. SITE NAME, LOCATION, AND DESCRIPI'lON
The INEL is an 89Q-square mile federal. facility operated by the DOE (Figure 1). The
primary mission of the INEL is nuclear reactor technology development and waste management.
Current land use at the INEL is industrial. Approximately 7,700 people are employed
at the INEL, with an esrim~red 600 employed at the Test Reactor Area., The nearest off-site
populations are in the cities of: Atomic City (13 miles southeast of the Test Reactor Area),
Area (17 miles west), Howe (14 miles north), Mud Lake (32 miles northeast), and Terreton (34
miles northeast).. .
The INEL has semi-desert characteristics with hot summers and cold winters. Normal
annual precipitation is 8.7 inches. . Twenty distinctive vegetation cover types have been identified
at the INEL. Big sagebrush, the dominant species, covers appro~m~tely 80 percent of the area.
The variety of habitats on the INEL support numerous species of reptiles, birds, and rn~mm~1~.
Underlying the INEL are a series of silicic and basalt lava flows and relatively minor amounts
of sedimentary interbeds. . The basalts immediately beneath the site are relatively flat-lying and
covered with 20 to 30 feet of alluvium.. The Snake River Plain Aquifer underlies the INEL and
was designated a sole source aquifer in 1992 pursuant to the Safe Drinking Water Act.
,
.
-------
The Test Reactor Area is located in the southwestern portion of the INEL approximately
47 miles west of Idaho Falls (Figure 1). The Test Reactor Area covers an area of approximately
l,7oo by 1,900 feet and is surrounded by a double security fence (Figure 2). Located inside the
fence are more than 73 buildings and 56 structures, such as tanks, cooling towers, laboratories
and offices. The facility contains three high neutron flux .nuclear teSt reactors: the Materials
Test Reactor, the Engineering Test ReactOr, and the Advanced Test Reactor. Only the
Advan~ Test Reactor is currently operational.
The area around the Test Reactor Area is relatively flat with the exception of several
construction rubble piles resulting from Test Reactor Area activities. Generally, the land surface
slopes gently from the west-southwest comer to the east-northeast comer of the facility. The
only surface water bodies at the Test Reactor Area are the four wastewater disposal ponds
located outside the security fence (Figure 2). The Big Lost River chaIme1 is located 4,480 feet
south of the Test Reactor Area. Drinking water. for employees at the TRA is obtained from
production wells in the northeast part of the facility (see Figure 7).
Chemical and radioactive wastewater have been and continue to be generated from
scientific and engineering research at the Test Reactor Area. wastewater discharged to unlined
surface ponds at the Test ReactOr Area percolates downward through the surficial alluvium and
the underlying basalt bedrock. A shallow perched water zone has formed at the interface
between the surficial sediments and the l~ permeable underlying basalt approximately 50 feet
below land surface. Further downward movement of groundwater is again impeded by a low
permeability layer of silt, clay, and sand encountered at a depth of about 150 feet. The deep
perched water zone occurs on top of this low permeability inteIbed. Figures 3 and 4 illustrate
. the vertical and areal extent, respectively, of the perched groundwater at the Test Reactor Area.
2. SITE HISTORY AND ENFORCEl\'IENT ACTIVITIES
2.1 Site History
The Test Reactor Area was established in the early 1950s to operate and teSt high neutron
flux nuclear test reactors. Wastewater. generated during operations is disposed of in the
wasteWater ponds at the Test Reactor Area. Six disposal units have been used that have
contributed to the formation and con~m;n~tion of the Perched W~ System; the retention basin,
chemical waste pond, sanitary waste (sewage) pond, warm waste pond, cold waste pond, and
former disposal Well U.S. Geological Survey (USGS)-53.
.
. The chemical composition of water discharged to the ponds has varied over the years.
Prior to 1962, all wastewater generated at the Test Reactor Area, except sanitary sewage, was
discharged directly to the warm waste pond. From 1952 to 1962, radionuclides, water softener
and ion excbange column regeneration fluids, reactor cooling water containing hexavalent
chromium, and other m;~U~neous wastes were all disposed to the warm waste pond. In 1962,
the regeneration fluids were diverted to the chen1ica1.:.vaste pond for. .disposal. . Water used in
. .
-------
the secondary reactor cooling system that contained hexavalent chromium was disposed to the
warm waste pond from 1952 until November 1964. .
Two different wells were used for disposal of waste water at the Test Reactor Area. From
1964 until 1972, the Test Reactor Area disposal well was used to dispose of the secondary
reactor cooling water. This disposal well injected directly into the Snake River Plain Aquifer
and did not contribute contaminants to the Perched Water System. After 1972, hexavalent
chromium was no longer used as a rust inhibitor in the cooling systems and was no longer
discharged to the disposal well or to the ponds. Use of the disposal well ceased in 1982. From
1960 to 1964, during peak wastewater generation, a second well, USGS-53, was used
intermittently to inject wastewater to the Perched Water System as the warm waste pond had
insufficient capacity.
The volume of discharged wastewater has been estimated for each pond system over the
operating period from 1952 to present, and is summarized in Table 1. For the period of record
from 1962 to 1990, a total of 6,770 million gallons of water" were discharged from the waste
streamS to the Perched Water System. Discharge volumes have remained near 200 to
300 million gallons per year, except for a 3-year period from 1979 to 1981 when discharge
volumes ~ere only 70 to 100 million gallons per year.
Water level elevations and areal extent of the deep perched groundwater fluctuate in
response to the volume of water being discharged to the surface ponds. Water movement in the
deep perched groundwater zone is both 1a.teIal and vertical. The size of the deep perched
groundwater zone has remained fairly uniform over the years except between 1979 to 1981 when
the size of the deep perched groundwater zone greatly decreased due to decreased discharge to
the surface ponds. With increased discharge ~ the surface ponds since 1982, the deep perched
groundwater zone has returned to its previous size.
2.2 Current Facility Operations
. Four disposal units are currently active and receive waste effiuent currently generated at
the Test Reactor Area. These are the. warm waste pond which receives radiologically
contaminated wastewater, the cold waste pond which receives primarily reactor cooling water
. with no radiological activity, the chemical waste pond which is used for disposal of wastewater
from ion exchange units and water softeners, and the sanitary waste ponds for sanitary (sewage)
wastes. These discharge ponds are identified on Figure 2.
Discharge rates to each pond are snmm~ri'7ed in Table 1. The greatest volume of
wastewater is discharged to the cold waste pond at approximately 500 gallons.per minute. W~
discharged to the cold waste pond is nonradioactive wastewater. The water is unconrnm;nated
secondary reactor cooling water and is discharged in significant volumes to the Perched W~
System.
. .
,-
u
-------
2.3 Previous Groundwater Investigations
A number of groundwater investigations have been conducted since 1949 in the vicinity
of the Test Reactor Area to characterize the quality of the Snake River Plain Aquifer. The
USGS began installing monitor wells and evaluating waste migration from the deep perched
groundwater to the Snake River Plain Aquifer in 1960. USGS monitoring parameters have
included nitrate, chloride, pH, specific conductivity, sodium, hexavalent chromium, total and
dissolved chromium, chromium-51, tritium, cobalt-OO, cesium-137, and strontium-90.
2.4 Enforcement
A Consent Order/Compliance Agreement (COCA) (EPA 1987) was entered into between
DOE and EP A ~ August, 1987, pursuant to the Resource Conservation and Recovery Act
(RCRA). The COCA required DOE to conduct an initial assessment and screening of all solid
waste and/or hazardous waste disposal units at the INEL. The release of radioactive and/or
hazardous contaminants to the disposal ponds and the deep injection well were identified and
evaluated during investigations conducted in accordance with RCRA corrective action
requirements.
As a result of the INEL's listing on the NFL in November 1989, DOE, EPA, and the
State of Idaho Department of Health and Welfare (IDHW) entered into a Federal Facility
Agreement and Consent Order (FF AlCO) (EP A 1991a) in December 1991 pursuant to CERCLA
and the Idaho Hazardous Waste Management Act. The FFAICO superseded the COCA and
established a procedural framework for agency coordination and a schedule for all FF AlCO
remedial action activities conducted at the INEL as a result of the NFL listing. The Perched
Water System Remedial Investigation (EG&G 1992) was conducted in accordance with the
FFAlCO.
3. mGHLIGHTS OF COMMUNITY PARTICIPATION
Community participation activities have been conducted in compliance with CERCLA
Sections 113(K)(2)(b)(i-v) and 117, and Section 24 of the FFAICO.
.
J'o announce the beginning of the Perched Water System investigation project, public
informational meetings were held in late July 1991 in Idaho Falls, Pocatello, Twin Falls, Boise,
and Moscow. The meetings were to explain the CERCLA process and to introduce the Perched
Water System investigation project to the public. These informational meetmgs were announced
via the INEL Reporter newsletter, which is distributed to INEL employees as well as the geneI3l
public, through newspaper and radio advertisements, and in an INEL press release. Personal
phone calls were made to key individuals, enVironmental groups, and organizations by the INEL
field offices in Pocatello, Twin Falls, and Boise. . The Community Relations Plan Coordinator
also made calls to community leaders in Idaho Falls and Moscow. .. . . . .
-------
When the investigation was completed, a Notice of Availability for the Proposed Plan
(USDOE 1992) for no remedial action of the Perched Warer System was published June 26,
1992, in the Post Register (Idaho Falls), Idaho State Journal (pocarello), Times News (fwin
Falls), Idaho Statesman (Boise), and Daily News (MoscowlPullman). A similar newspaper
advertisement appeared in the same newspapers the following week repeating the announcement
of the public meeting locations and times. Personal phone calls, as noted above, were also made
to inform inrerested individuals and groups about the opportunity to comment.
The Proposed Plan for the remedial action of the Perched Warer Sysrem was mailed
June 26, 1992, to 6,500 individuals on the INEL mailing list. It included a cover letter from
the Director of the Environmental Restoration Division of the DOE Idaho Field Office urging
citizens to comment on the Proposed Plan and to attend public meetings. Copies of the Proposed
Plan . and the Administrative Record were available to the public in six regional INEL"
information repositories: the INEL Technical Library in Idaho Falls; and city libraries in Idaho
Falls, Pocarello, Twin Falls, Boise, and Moscow. The original documents comprising the
Administrative Record are located at the INEL Technical Library; copies are present in the five
other libraries. These copies were placed in the infonnation repository sections or at the
reference desk in each of these libraries.
The public comment period on the Proposed Plan for the Perched Warer System was held
from July 6 to August 5, 1992. No requests for extensions were made. Technical briefings
were conducted via speaker phone to interested members of the public in Twin Falls, Moscow,
and Pocate1lo on July 13, .14, and 15, 1992, respectively. Public meetings were held July 20,
21, 22, and 23, 1992, in Idaho Falls, Burley, Boise, and Moscow, respectively. At these
meetings, representatives from DOE, EP A, and IDHW discussed the project, answered
questions, and received public comments. Verbatim transcripts of each public meeting" were
prepared by a court reporter. In addition to" accepting oral comment during the meetings,
written comment sheets. and an audio tape recorder were made available at the meeting to accept
public comments. Written comments were accepted throughout the 3
-------
4. SCOPE AND ROLE OF OPERABLE UNIT AND RESPONSE ACTION
Under the FFAlCO, the INEL is divided into ten waste area groups (WAGs) which
generally correspond to facility areas. The WAGs are further subdivided into operable units
(OUs). The Test Reactor Area has been designated WAG 2, and the Perched Warer System has
been designated OU 2-12, one of the thirteen OUs identified at the Test Reactor Area. OU 2-
12~ the subject of this Record of Decision, addresses the risk due to infiltration of the
contaminated perched water into the Snake River Plain Aquifer. The following three separate
OUs.will address sediment/soil contamination resulting from the wastewater discharge:
OU2-09
OU 2-09 will evaluate contaminated sediments in the cold waste pond and the
sewage lagoons. Preliminary investigations are currently underway to determine.
if the sediments in the sewage lagoons or the cold waste pond present an
unacceptable risk.
OU 2-10
Risk calculations have already demonstrated that the warm waste pond sediments
currently pose an unacceptable risk. An Interim Action Record of Decision for OU
2-10 was signed December 5, 1991, which addresses the pond sediments. A new
lined replacement pond for the warm wasteWater is currently under construction.
The existing warm waste pond will be closed in 1993 when the new pond is
completed, at which time wasteWater ~ no longer be discharged to the pond.
OU 2-11
-
au 2-11 consists of the retention basin and the Test Reactor Area disposal well.
The disposal well was used to inject wastewater directly to the Snake River Plain
Aquifer and was an additional source of aquifer contmrl.nation; however, it was not
a source to the Perched Water System.
The retention basin is part of the warm wasteWater system. Wastewater passes
~ugh the baSin to allow short-lived tadi,onuclides time to decay before reaching
the pond. Evidence of a leak was discovered in the retention basin and was studied
in 1971 (Langford, 1971). The preliminary investigation for 'OU 2-11 will
determine if the con~min~ted sediments resulting from the leakage present an
unacceptable risk. .
In addition to these three investigations, a final WAG 2 investigation (OU 2-13) will be
conducted to evaluate reJ11~in;ng' sources within theTest Reactor Area and consider the potential
risk from. the perspective of the entire WAG. . This investigation is scheduled .to begin in 1996..
-------
au 1 Q-4 is the Comprehensive/Snake River Aquifer RIfFS investigation at the INEL.
After information concerning each source is evaluated in the individual WAGs, risks will be
investigated for the INEL in its entirety as au 10-4 with particular attention given to the Snake
River Plain Aquifer. An evaluation of the impact to the Snake River Plain Aquifer from the
Test Reactor Area will be included in the INEL-wide investigation.
5. SUMl\fARY OF SITE CHARACTERISTICS
5.1 Geology and Hydrology
The INEL is located along the northern edge of the Eastern Snake River Plain, a 50- to
7Q-mile wide northeastern trending geologic basin extending from the vicinity of Twin Falls on
the southwest. to the Yellowstone Plateau on the northeast The Eastern Snake River Plain is
underlain by a substantial volume of volcanic rocks with relatively minor amounts of sediment,
except along its margins where drainages emerge from the nearby mountain ranges. The Test.
Reactor Area is underlain by 30 to 50 feet of surficial alluvium and a thick sequence of fractured
basalt flows with thin sedimentary interbeds. These alluvial sediments are. primarily composed
of sandy gravel with minor amounts of silt and clay. Quartz is the major mineral component
of the alluvium, followed by plagioclase and alkali feldspar and minor amounts of clays.
. Fractured basalt flows underlie the surficial alluvium and are separated by sedimentary
interbeds that vary in thickness and lateral extent. The most extensive interbed occurs
approximately 150 feet below the surface. Similar to the surficial alluvium, quartz is the major
mineral component of the sedimentary interbeds, followed by plagioclase and alkali feldspars.
The Snake River Plain Aquifer occurs in this sequence of basalt with sedimentary. interbeds at
a depth of approximately 480 feet beneath the Test Reactor Area (see Figure 3).
5.1.1 Surface~ater
Most of the INEL is located in a topographically closed drainage basin, referred to as the
Pioneer Basin, where the Big Lost River, Little Lost River, and Birch Creek once drained from
the mountain ranges to the west and . north. Today, most of the water flowing in these streamS
is diverted upstream of the INEL for irrigation purposes.
The Big Lost River is the principal Iiatura1 surface-water feature on the INEL and is the
.closest major drainage to the Test Reactor Area. The Big Lost River has not flowed on the
INEL since 1984.. Neither the Test Reactor Area facilities nor ponds are located within the 100-
or 500-year flood plain of the Big Lost River.
,
5.1.2 Perched Water
The presence of perched water at the Test Reactor Area is directly related to infiltration
. from wastewater disposal ponds. Perched groundwater occurs when downwarcLflow. of the .'
. .
-------
wastewater to the aquifer is impeded by fine-grained .sediments and/or dense basalt flows having
relatively low permeability. Two distinct perched water zones, sh2110w and deep, have been
recognized at the Test Reactor Area (see Figure 3). The shallow perched groundwater occurs
in the immediate vicinity of the ponds and retention basin, and forms on the interface between
the surficial alluvium and the underlying basalts at about 50 feet below land surface.
. The deep perched groundwater is caused by low-permeability sediments. and/or sediment
infilling of fractures within the interbedded basalt-sediment sequence. The top of this
interbedded basalt-sediment sequence begins at depths of approximately 140 feet below land
surface and ends at depths of about 200 feet below land surface. This perching zone includes
silt, clay, sand, cinders, and gravel, and appears to be laterally continuous in the vicinity of the
Test Reactor Area.
Water levels in the deep perched monitoring wells and the areal extent of the deep perched
groundwater have fluctuated in response to the volume of ~ter discharged to the surface ponds.
During March 1991, the areal extent of the deep perChed groundwater was about 6,000 by 3,000
feet (see Figure 4). The volume of deep perched groundwater was calculated to be
approximately 1.4 billion gallons at these dimensions.
5.1.3 Snake River Plain Aquifer
The eastern portion of the Snake River Plain Aquifer extends from Ashton, Idaho, on the
northeast to Hagerman, Idaho, on the southwest. The aquifer occurs within a series of basalt
flows with interbedded sedimentary deposits. Recharge to the aquifer is primarily due to valley
underflow from the mountains to the north and northeast of the plain, and from infiltration of
irrigation water. Recharge to the aquifer within the INEL boundaries is primarily due to
underflow from the northeastern portion of th~. plain and from the Big Lost River.
Site-wide water-level data show that the general direction of groundwater flow across the
INEL is toward-the south-southwest at an average gradient of about 4 ftImi. The depth to the
water table varies from about 200 feet below the SUIface in the northern portion of the INEL to
about 900 feet below the surface in the southern portion. At the Test Reactor Area, the depth
to groundwater is at approxim~tely 480 feet and the gradient is about 2 ftImi.
Aquifer permeability is controlled prim~rily by fractures, fissures, and voids along the.
upper and lower contacts of basalt flows, large interstitial voids, and intergranular pore spaces.
Based on site--specific data, the average groundwater flow velocity at the Test Reactor Area was
estim~ted to be 4.3 feet per day. .
S.2 Nature and Extent of CODVamin9tion
All available data were used to evaluate the nature and extent of groundwater
contamination for the Perched Water System Remedial.Investigation. In addition to the data
collected by the USGS from 1949 to 1990, groundwater was sampled. between January and .
-------
March, 1991 for a comprehensive water quality evaluation specifically for this investigation.
The purpose of this sampling effort was to analyze for additional parameters not routinely
monitored by USGS. USGS monitoring parameterS have included nitrate, chloride, pH, specific
conductivity, sodium, hexavalent chromium, total and dissolved chromium, chromium-51,
tritium, cobalt-60, cesium-137, and strontium-90. Groundwater samples were collected from
the existing monitoring wells and production wells including six shallow perched wells, 22 deep
perched wells, and 11 Snake River Plain Aquifer wells. The location of the shallow perched,
deep perched, and Snake River Plain Aquifer wells sampled for this investigation are identified
on Figures 5 through 7.
Samples were analyzed in 1991 for volatile organics, acrylonitrile, semivolatile organics,
pesticides, metals, hexavalent chromium, and radionuclides. In addition, samples were analyzed
for field parameters of specific conductivity, pH, and temperature. Laboratory analyses were
performed for the water quality parameters: alkalinity, fluoride, total dissolved solids, nitrate,
nitrite, phosphate, chloride, silica, and sulfate. Results of the 1991 groundwater sample analysis
are discussed below. and summarized in Tables 2 and 3.. As a point of comparison,
concentrations .observed in the Perched Water System were compared to primary or secondary
maximum contaminant levels ~CL) and site-specific background. A primary MCL is the
concentration of a constituent allowed in a public drinking water system determined under the
Safe Drinking Water Act. A secondary MCL pertains to control of contaminants in drinking
water that primarily affect aesthetic qualities. Table 4 summarizes the drinking water standards
and background concentrations for inorganics, organics and radionuclides.
5.2.1 Shallow Perched Zone
Ornmcs
Volatile organic compounds detected above the quantitation limit in shallow wells near the
cold waste pond include low concentrations of toluene, xylene, and various derivatives of
benzene, which are common constituents of hydrocarbon fuels. Trace volatile organics were
. also detected in wells beneath the chemical waste pond. Of the semi volatile organic compounds
analyzed, low concentrations of bis(2-ethylhexyl)phtha1ate appear to be the most prevalent and
were detected in shallow wells beneath the retention basin and the cold waste pond.
Inon!anics
Mercury, manganese, and iron were the only metals detected which exceeded MCLs in
the filtered samples of shallow perched groundwater. Results of metals analyses on unfiltered
samples collected from shallow perched zone wells indicated that several metals exceeded their
MCLs. These metals included cadmium, chromium, lead, manganese, and mercury.
Radionuclides
- .
Several radionuclides were detected in Wells SB.01,.SB-02, and S~ 1ocated.near the
-------
retention basin. The radionuclides detected above MCLs include cobalt-60, cesium-137,
americium-241, tritium, and strontium-90.
5.2.2 Deep Perched Groundwater Zone
On!anics
. Volatile organic compounds detected above the quantitation limit in the deep perched water
included chloroform, methylene chloride, toluene, benzene, and 1,1,1-trichloroethane. Of the
semivolatile organic compounds detected, low concentrations ofbis(2-ethylhexyl)phthalate were
the most widespread. No pesticides were detected in the deep perched groundwater.
Inon!anics
Concentrations of cadmium, chromium, and manganese in the filtered samples collected
in the deep perched wells were above MCLs. Cadmium concentrations exceeded the MCL of
10 p.g/L in the filtered water sample from one well. Filtered groundwater samples from four
wells near the chemical waste disposal pond exceeded the MCL for manganese. Fluoride,
sulfate, and phosphate were detected at elevated concentrations in the deep Perched Water
System.
Chromium is the most frequently detected metal in the deep perched zone. Chromium
concentrations were detected up to 1125 p.gIL which is well above the MCL of 50 p.gIL. The
highest concentrations of chromium occur in the north central portion of the deep perched
groundwater zone, north of the warm waste pond.
Radionuclides
Of the Iadionuclides analyzed, tritium and strontium-90 were detected above the MCL of
20,000 pCiIL
-------
groundwater samples from the aquifer wells at estimated concentrations less than 1 /Lgll.
Phthalates were the only semiyolatile organic compounds detected. The presence of phthalates
is not likely to be the result of site activities because phthalates typically occur in plastics and
are also common laboratory contaminants. No pesticides were detected.. Of the volatile and
semivolatile organics detected, none were detected above MCLs.
,
InoI'2anics
Chromium was the only metal detected in groundwater samples from the Snake River
Plain Aquifer which exceeded MCLs. Since 1968, the concentration of total chromium in
samples from down-gradient Well USGS-65 has generally declined from about 750 /Lg/l to
current levels. of about 179 /Lg/L This decline is anticipated to continue because chromium has
not been disposed at the Test Reactor Area since 1972~
Radionuclides
Tritium was the only radionuclide detected above natural background levels or MCLs.
Since 1970, the concentration of tritium in samples from Well USGS-65 has generally declined
from about 220,000 pCiIL to current levels of about 61,000 pCiIL. This decline will likely
continue once the new lined evaporation ponds for warm waste disposal are operational, and the
tritium source is eliminated. The tritium concentrations in down-gradient Well USGS-76 have
remained less than the MCL since 1965.
5.2 Groundwater Model
A computer model was developed using both historic and recent information concerning
groundwater flow and con~min::l1ion in the Perched Water System and in the underlying Snake
River Plain Aquifer in the vicinity of the Test Reactor Area. The computer mOdel predicted
concentrations.from the present through a point in time 125 years in the future. These predicted
concentrations were then used in the risk assessment calculations. Development of the model
began with identification of the assumptions on which the model is based. The assumptions are
based on existing knowledge of groundwater flow in the vicinity of the Test Reactor Area. A
comparison of modeling results was made with historical data to ensure that it represented
groundwater flow in the Perched Waw System in order to provide confidence in the useability
of the model for predictions.
Among the assumptions on which the model is based are: 1) the Warm Waste Pond, as
the major source of contamination, will be removed from service within one year. This
assumption is based on the fact that construction of a new lined replacement pond has already
begun, and; 2) The Cold Waste Pond will remain in service at least through the year 2007. This
is based on the expected operational lifetime of the Test Reactor Area. which would then be
followed by a lO-year decommissioning period through the year 2017.
. .
. .
-------
6. SUMMARy OF SITE RISKS
Trends simulated by the model are, shown in. Figures 8 through 10 for several key
contaminants. in the Snake River Plain Aquifer. In addition to chromium and tritium, which
currently exceed MCLs, the only other contaminant predicted by the model to exceed its MCL
in the Snake River Plain Aquifer is cadmium.
The risk assessment for the Perched Water System considered both human health and
~logical risks. The human health risk assessment included calculations of risk for future (m
. year 2115) and near-term receptors. The risk assessments were conducted in accordance with
the EP A Risk AssesS11W11 Guidance for Superfund. Volwne I: Human Health Evaluation Manual
(EPA 1989b) and Volwne II: Environmental AssesS11W11 Manual (EPA 1989f) and other EPA
national guidance. The risk assessment methods and results are summarized in the following
sections.
.6.1 Human Health Risk Assessment
The risk assessment consisted of contaminant identification, exposure assessment, toxicity
assessment, and human health risk characterization. The objective of the contaminant screening
was to identify chemic3ls based on concentration and toxicity, that are most likely to contribute
significantly to risks. The exposure assessment detailed the exposure pathways that exist at the
site for various receptors. The toxicity assessment documented the adverse effects that may be
caused in a receptor as a result of exposure to a site contaminant.
The human health risk assessment evaluated potential risks associated with exposure to
chemical contaminants present in the Snake River Plain.. Aquifer due to infiltration of
contaminants from the Perched Water System~ Both carcinogenic and non-carcinogenic risks
were evaluated. The health risk evaluation used both the exposure concentIations and the
toxicity data to determine a hazard index for potential noncarcinogenic effects and a cancer risk
level for potenfial carcinogenic contaminants. In general, a hazard index of less than 1 indicates
. that even the most sensitive population is not likely to experience adverse health effects. The
excess cancer risk level is the increase in the probability of contracting cancer. The NCP
acceptable risk range is 1 in 10,000 to 1 in 1,000,000. An excess lifetime cancer risk of 1 in
10,000 (lQ4) indicates that an individual has up to a one chance in ten thousand of developing
cancer over a lifetime of exposure to a site-related contaminant.
Key steps taken in the risk assessment process are summarized in Sections 6.1.1 through
6.1.5.
6.1.1 Identification of ConVlmin~nts of Concern
. .
Potential contaminants of concern are those that are released to the environment at a site
that may pose a health risk to humans who come into contact with them. A contaminant
screening process was completed for the Perched Water System to reduce the number of
-------
chemicals carried through the computer model and quantitative risk assessment, and focus on
those contaminants that contribute significantly to the overall risk. The first step in contaminant
identification was to compare analytical results for each chemical from the Perched Water
System investigation to the background concentration for that chemical. Background
concentrations were derived by calculating the arithmetic mean concentration for each chemical
from the analytical data from production wells TRA-03 and TRA-04 and the Site 19 well. These
wells are upgradient from the shallow and deep perched zone and are unaffected by
contamination from the Perched Water System. The next screening step was to consider the
half-life and concentration of detected radionuclides. Radionuclides with a half-life of less than
5-years were eliminated at this step because they decay rapidly. Next, an evaluation of the
concentration, toxicity and mobility of each contaminant was completed to determine the
contribution of each contaminant to the totll risk. Contaminants that represented a small
percentage of the risk were eliminated (less than 1 percent). Although chromium, tritium, and
strontium-90 represent less than 1 percent of the site risk, these contaminants were retained
because of the historical association with the facility. Table 5 lists the contaminants of concern
that were included in the risk assessment.
. .
6.1.2 Exposure Assessment
Exposed Populations
Only exposure pathways deemed to be complete (i.e., where a plausible route of exposure
can be demonstrated from the site to a receptor) were quantitatively evaluated in the risk
assessment. The populations at risk due to exposure to the perched water were identified by
considering both current and future use scenarios. .
Currently, public access to the Test Reactor Area is restricted so public exposure to the
perched water is not likely. Exposure to contaminants in the Perched Water System by site
employees is also unlikely, as the Perched Water System is approximately 50 to 150 feet below
the ground surface and is not used. The potential exposure to contaminants in the perched water
during environmental Sampling is addressed separately by health and safety documentation for
each individual activity. The potential for cmrent exposure to contaminants in the Perched
Water System was judged to be low and risks associated with current exposure scenarios were
not evaluated. Production wells at the TRA from which workers obtain drinking water from the
Snake River Plain Aquifer are upgradient of the. contamination and are monitored regularly to
ensure that they produce clean water.
Future contact with the Perched WatJ:I System is unliKely because the Perched Waw:
System is predicted to dissipate within about 7 years of ceasing disposal of wastewater to the
ponds at the Test Reactor Area according to the modeling results. Future exposure resulting
from the migration of contaminants from the Perched Warer System to the Snake River Plain
Aquifer was evaluated for a hypothetical resident living on the site.
. .
. .
-------
An agricultural scenario was detennined to be the most probable scenario for future use
at the Test Reactor Area. The exposed population would consist of site resident farmers,
including both adults and children. For the purpose of the risk assessment, onsite residence with
agricultural land use was assumed to occur 125 years in the future based on planned operations
at the Test Reactor Area. This period was selected based on an expected 25 years of operation
. and decommissioning followed by 100 years of institutional controls.
Exposure Pathways
The exposure pathways identified for the future resident fanner scenario consist of:
. Ingestion of groundwater from domestic wells in the Snake River Plain Aquifer
. Ingestion of garden grown fruits and vegetables irrigated with Snake River Plain
Aquifer water
. Ingestion of domestically grown livestock.
E~sure Point Concentrations
Chemical concentrations at points where the potential for human exposure is expected to
occur are necessary to evaluate the chemical intake of potentially exposed individuals. Exposure.
pathways from the source to receptors were evaluated using a groundwater transport computer
model. The results of the computer modeling are expressed as predicted concentrations in
drinking water from the Snake River Plain Aquifer. The concentrations predicted by the model
which were used in the risk assessment are shown on Table 6. Groundwater tIansport modeling
was used to estimate future concentrations of the chemicals of concern in the Snake River Plain
Aquifer. These concentrations are considered reasonable maximum concentrations because the
highest model-predicted concentrations in the Snake River Plain Aquifer were selected for the
risk assessment exposure concentrations. This is generally directly below the perched zone in
the upper part of the Snake River Plain Aquifer before any dilution in the aquifer would occur.
Exposure to con~m;n~nts of concern from the Perched Water System could result from
ingestion of crops irrigated with conrnmin~ted water pumped from the Snake River P1ain
Aquifer. The potential exists for conrnminants to accumulate in sUIface'soils as a result of
irrigation and may be available for plant uptake. The concentration of contaminants in onsite
soils as a result of irrigation with cont3minated water was calculated in the Risk Assessment by
applying recommended methods in Risk Assessment Guidance for Superfund. Human Heillth
Evaluation Manual Pan A. l111erim Final (EP A, 1989a).
Contaminant concentrations in crops were assessed by estimating uptake and accumulation
through roots from the soil. Separate calculations were performed for vegetative (leaf and root)
and reproductive (fruit and seed) portions of crops..: . . .'. . .. . . .
-------
Chemical Intake by Exposure Pathway
Chemical intakes for each exposure pathway were based on the exposure point
concentrations calculated from the modeled concentrations in the Snake River Plain Aquifer
directly below the Test Reactor Area and other exposure parameters, such as water ingestion
rates, crop and livestock ingestion rates, body weights, and exposure frequency and durations
recommended in the risk assessment guidance.
There .are multiple conservative or upper bound assumptions in the health risk
characterization for the Perched Water System:
. An individual consumes all drinking water from an onsite well
. An individual derives a reasonable maximum amount of his diet from onsite sources
. An individual lives for 30 years at or near the site (90 percent of time spent in one
house)
. An individual has continuous, daily exposure to constituents detected at the site
. Cancer risks are linearly related to exposure (i.e., carcinogenic effects bave no
thresholds)
. Contaminant concentrations remain constant over the exposure period
. Exposure remains constant over time .
. Risks are additive
. All intake of contaminants is from the exposure medium being evaluated.
6.1.3 Toxicity Assessment
Tbe toxicity assessment addresses the potential for a chemical to cause adverse effects in
exposed populations and estimates the relationship between extent of exposure and extent of toxic
injury ,(i.e., dose-response relationship). Qualitative and quantitative toxicity information for
the contaminants was acquired through evaluation of relevant scientific literature (e.g., Health
Effects Assessment SU11Z1TUlTY Tables, EPA 1991). The most directly relevant data came from
human studies. Most of the useable information on the toxic effects of chemicals came from
controlled animal experiments.
.-
-------
6.1.4 Risk Characterization
Risk characterization is the process of combining the results of the exposure and toxicity
assessments. This process provides numerical quantification relative to the existence and
magnitude of potential public health concerns related to contamination deteCted at the site. A
summary of the calculated future carcinogenic and non-carcinogenic risk estimates is presented
in Tables 7 through 10.
Risk calculations are divided into carcinogenic and non-carcinogenic categories. The
calculation of health risks from potential exposure to carcinogenic compounds involves the
multiplication of cancer slope factors for each carciJ)ogen and the estimated intake values for that
chenrical. .
Noncarcinogenic risk is as~ssed by comparison of the estimated daily intake of a
contaminant to its applicable Reference Dose. A Reference Dose is a provisional estimate of
the daily exposure to the human population that is likely to be without an appreciable risk of
deleterious effects during a portion of the lifetime. The estimated daily intake of each chemical
by an individual route of exposure is divided by its Reference Dose and the resulting quotients
are calculated to provide a hazard index.
Future Risk
Lifetime cancer risks from potential exposure to each carcinogenic contaminant were
added across all of the exposure pathways. Cancer risks from the different routes of exposure
were assumed to be additive, as recommended by EP A guidance. It should be noted that adding
cancer risks from different exposure routes provides health-protective risk estim~tes. The excess
cancer risk to the future (year 2115) onsite residential farmer is shown in Tables 7 and 8. This
risk (5.6 x l(t~ is dominated by the ingestion of cobalt-60 through the drinking water pathway,
but is well below the acceptable 10'" to 1~ risk range.
The potential future exposure to non-carcinogenic contaminants fal1s below the individual
Reference Doses for each contaminant of concern. Non-carcinogenic hazard indices are
presented in Tables 9 and 10 for child and adult exposures, respectively. The non-carcinogenic
constituent at the site that poses the greatest potential for adverse health effects at year 2115 is
cadmium (HI =0.17). These results suggest that chronic exposure to modeled concentrations of
contan1inants in the Snake River Plain Aquifer are unlikely to represent significant non-
carcinogenic health effects to humans. .
Near-Tenn Risk
In addition to the risk calculations, coD~min3nt concentrations were compared to MCLs
for both the Perched Warer System and the Snake RDler Plain Aquifer. Concentrations for
-------
several contaminants currently exceed these levels in the Perched Water System. However,
there is no risk associated with these contaminants because there is no current use of the Perched
Water System itself. Although tritium and chromium exceed MCLs in the aquifer, there is also
no current use of the contaminated water in the Snake River Plain Aquifer beneath the Test
Reactor Area. The closing of the warm waste pond, scheduled for 1993, will eliminate future
discharge of tritium to the Perched Water System, and therefore the concentrations .of tritium
(with a half-life of 12.5 years) in the Snake River Plain Aquifer will decrease due to radioactive
decay~ The computer model predicts the concentration of tritium will meet its MCL during the
year 2004 (See Figure 9). Concentrations of chromium in the Snake River Plain Aquifer have
declined since 1972 when discharge of chromium to the warm waste pond ceased. Chromium
is predicted to meet its MCL by the year 2016. The model also predicted that cadmium would
exceed its MCL in the late 1970s and would again drop below the MCL by 2027 (See Figure
10). Cadmium levels have never been observed above the MCL in water samples collected from
Snake River Plain Aquifer wells at the TRA. Therefore, the model is considered to be
conservative for cadmium and it is not certain that the cadmium MCL will be exceeded. For
several contaminants of concern, including cadmium, the model used the average concentration
in the shallow perched water for contaminant input to the system because there was limited data
on the amount of the contaminants that had been released through time. This input concentration
was then assumed to remain constant throughout the life of the TRA facility which is nnH1cely
since the Warm Waste pond will be eliminated as a source of contamination in the next year.
Near-Term Human Health Risk Assessment
Due to the uncertainty of future land use at the INEL and the fact that MCLs are currently
exceeded in the Snake River P!3in Aquifer, the computer groundwater modeling results were
used to evaluate near-term risks. This evaluation was completed to provide an estimate of the
risk posed by the contaminants that currently exceed, or are predicted to exceed, MCLs in the
Snake River P-lain Aquifer (chromium, tritium, and cadmium). This assessment evaluated
ingestion of contaminated groundwater for chromium, tritium, and cadmium and vapor inhalation
for a residential adult receptor for several periods in the future.
Groundwater model results were used to calculate exposure concentrations for five 3D-year
periods. The scenarios include years 1990 to 2020, 1995 to 2025, 2000 to 2030,2005 to 2035,
and 2010 to 2040. Average concentrations for each thirty-year period are shown on Table 11.
The lifetime excess cancer risk due to tritium under the 1990 to 2020 scenario is estiro3tffl
to be 3 x 10"'. This calculated risk then decreases with time and falls well below one chance
in 10,000 which is within the acceptable target risk range for later years. Table 12 summarizes
the results from the near-term risk assessment for tritium. .
The hazard quotients for chromium and cadmium were calculated for the five 3O-year
exposure scenarios. For the 1990 to 2020 time period, .the hazard quotient for chromium and
cadmium were estimated to be 0.6 and 1.3~ respectively.. The hazard quotient for cadmium is..
-------
one or below thereafter. These results are summarized in Table 13.
6.1.5 Uncertainty
Risk assessments are subject to uncertainty from sampling and analysis, fate and transport
estimation, exposure estimation, and toxicological data. Uncertainty was addressed by using
health-protective assumptions that systematically overstate the magnitude of health risks. This
process bounds the plausible upper limits of risk and facilitates an infonned risk management
decision. The following is a summary of risk assessment uncertainties:
. Uncertainty associated with sampling and analysis includes the inherent variability
(standard error) in the analysis, representativeness of the samples, sampling errors, and
heterogeneity of the sample matrix. While the quality assurance! quality control used
in the investigation serves to reduce such errors, it cannot eliminate all errors
associated with sampling and analysis. The samples were analyzed usingEPA-
approved analytical methods. These data were evaluated by the agencies to ensure they
were representative of the area of investigation.
. Sources of uncertainty arising from the fate and tranSpOrt modeling include the
contaminant concentration in the effluent waste stream, the impact of mixing in the
shallow perched water zone, and uncertainty of assumed adsorption coefficient values
for each contaminant. Additional parameters that were most sensitive include the .
infiltration rate of wastewater and the saturated hydraulic conductivity of the lower
interbed at about 150 ft. The model was most sensitive to the values for contaminant
attenuation and the concentration used for infiltrating wastewater. The hydraulic
conductivity of some model layers was also found to be a sensitive parameter.
An example of the sensitivity of the infiltration parameter is illustrated by the
concentrations for cadmium. The modeled concentration for cadmium, as well as other
contaminants of concern, is probably higher than what will actually occur in the Snake
River Plain Aquifer. This is attributed to the higher than normal infiltration (recharge)
rate used in the model. The infiltration rate used in the model was 15 cm/yr~ A more
realistic value is 1.5 to 5 em/yr. Thus, the modeled cadmium concentration of 15
p.gIL at approximately 2010 is probably an overestimate and adds to the conservatism
of the risk assessment. The projected concentration for cadmium. may not exceed the
'. Federal Drinking Water Standard of 5 p.gIL.
. Because concentrations of conhlm1nants vary over time and the calculated risks are
representative of modeled concentrations at only one point in time, this temporal
variation is another source of uncertainty. .
. The toxicological database is also a source of uncertainty. The EP A outlined some of
the sources of uncertainty in its Guidelines for Cardrwgen Risk Assessment, (EP A
1986). They include extrapolation froin high to low doses and from (ln1m31~ to
-------
humans; species differences in uptake, metabolism, and organ distribution; species
differences in target site susceptibility; and human population variability with respect
to diet, environment, activity patterns, and cultural factors.
6.2 Ecological Risk Assessment.
The ecological risk assessment qualitatively evaluated the potential ecological effects
associated with the presence of the Perched Water System. This ecological evaluation follows
the Risk Assessmenl GuidancefoT Supeifund Volume 11 (EPA 1989b). The evaluation focused
on the same contaminants and receptor locations as those evaluated in the human health
assessment. Objectives of the ecological risk assessment are to qualitatively evaluate the
potential risk to ecological receptors from the contaminants in the Perched Water System. The
assessment identified sensitive norihuman species and characterizes potential exposure pathways
including ingestion of contaminated groundwater or vegetation, and contaminant uptake by
plants. Similar to the human health risk asSessment, no credible current use exposure scenario
exists. The future use exposure scenario included using contaminated groundwater for irrigation,
with contaminants entering the food chain which could result in potentially complete exposure
pathways throughout the ecological system.
The approach used in the ecological risk assessment is consistent with EP A guidance for
evaluating ecological risk. The steps included identification of contaminants, assessment of
potential exposure pathways, and characterization of threats to exposed biota.
6.2.1 Exposure Assessment
Table 5 lists the contaminants of concern identified in the Perched Water System. The
ecological scenarios assume that wildlife would inhabit the site. This assessment was limited
to exposure due to contamination of the Perched Water System. Consequently, migration of the
contaminated perched groundwater to a potential exposure point via some pathway was
considered to be a prerequisite to exposure.
For an ecological risk to exist, there must be a complete pathway for the contaminant to
reach an ecological receptor. Either a receptor would need to reach the Perched Wati=r System
or the cOntaminated water would need to get to the surface. The Perched W~ System does
not recharge any local surface . water, and no evidence of any resurfacing exists at. the site.
.Although some of the animals at the site are bUIIOWing J11~mm~l~J burrowing activity is
usually limited to a few feet below the surface. Therefore, contact with the Perched Water
SyStem is not likely. While sagebrush has a deep root system (up to 99 in.), it is not likely to
reach the perched water. Some of the treeS could have a root systeni deep enough to penetrate
to the shallow Perched Warer System; however, the nearest treeS are 1 mile from the site and
not in the plume area. Therefore, no complete exposure pathway exists between the
contamin3.nts and ecological receptors under the current land use scenario.
.-
19
-------
Similar to the human risk assessment, the ecological risk assessment considered a future
land use scenario that includes pumping contaminated water from the Snake River Plain Aquifer
onto the surface for agricultural irrigation purposes. Contaminants then enter the food chain
resulting in potentially complete exposure pathways throughout the ecological system.
6.2.2 Risk Characterization
" Although ecological receptors are currently present on the site, contact with contaminants
of concern is not possible under current site conditions. The depth to the Perched Water System
and the absence of any resurfacing phenomena prevents contact with the contaminants of
concern. Because no complete exposure pathways are identified in the present scenario, the
contaminants of concern do not appear to pose a potential ecological risk. "
Under a future scenario, it is plausible that ecological receptors could come into contact
" with contaminants currently in the Perched Water System as these contaminants migrate to the
Snake River Plain Aquifer. This water then is pumped to the surface for agricultural use. The
water used for agricultUral purposes may provide a source of contact to ecological receptors for
ingestion. Dermal contact with water and soil is also possible as chemicals are deposited onto
soil as a result of irrigation. IIi addition, plants can cache some of the chemicals of concern, and
transfers between trophic levels are possible for some of the chemicals with longer biological
half-lives. However, given the concentration of the contaminants of concern, unacceptable risk
to ecological receptors is not judged to be likely.
7. DFSCRJPI'ION OF NO ACTION DECISION
Based on results of the human health ml~ ecological risks assessments, the contaminants
of concern do not pose unacceptable risks to human health or the environment for the future use
scenarios evaluated for the Snake River Plain Aquifer beneath the Test Reactor Area.
Therefore, no remedial action is necessary for the Perched Water System OU at the Test Reactor
Area. Because this conclusion is based on predictive computer modeling, water quality
" monitoring activities will"be conducted to: (1) evaluate the contaminant concentration trends in
the Snake River Plain Aquifer, and (2) evaluate the effect of discontinued discharge to the warm
waste pond and fate of contaminants in the Perched " Water System.
A groundwater monitoring plan will be developed with the approval "of EP A and IDHW.
The plan will be a primary document as defined in the FF AfCO and will be submitted for
agency review 45 days after signature of this Record of Decision. The plan will define the wells
that will be monitored, parameters that will be monitored, frequency of monitoring, reporting
requirements and criteria for future decisions. Monitoring data will be made available in the
information repositories.
As stated previously in the Declaration Statement, a 3-year statutory review of the No
Action decision will be conducted to ensure that human health and the environment are being
protected and that the assumptions upon which the No Action decision was based are still valid.
-------
Should the three-year review or post-ROD monitoring or a change in any assumptions used to
arrive at the decision indicate that other actions or modifications of the No Action response are
required, these will be initiated by the agencies, as appropriate, and in accordance with the
FFAICO.
In addition, it should be noted, as discussed in Section 4, that the WAG 2 Comprehensive RIlFS
Will evaluate risk from the perspective of the entire TRA facility.
8. EXPLANATION OF SIGNIFICANT CHANGES
There are no significant changes between the recommendations presented in the Proposed
Plan and this Record of Decision.
. .
-------
REFERENCES
Batchelder, H.M., 1981, Radioactive waste management information for 1980, Idaho Oper.
Rep. IDO-10055(80). .
EG&G Idaho, Inc., 1992, Remedial Investigation Repon For The Test Reactor Area Perched
. Water System (Operable Unit 2-12), June 1992.
EPA, 1986, "Guidelinesfor Carcinogenic Risk Assessment," Federal Register 51, pp.
33992-34003.
EPA, 1987, Consent Order/Compliance Agreement 1085-10-07-3008 in the matter of: the
.. United States Environmental Protection Agency and the United Stales Depanment oj
Energy Idaho National Engineering Laboratory, ID4890008952 proceeding untkr Section
300 8(h) of the Resource Conservation and Recovery Act, 42 USC, Section 6928(h), July
1987.
EP A, 1989a, Risk Assessment Guidance for Supeifund. Human Health Evaluation Manual Part
A. Interim Final, OSWER Directive 9285.701A, December 1989.
EP A, 1989b, Risk Assessment Guidance for Supeifund, Volume II - Environmental Evalumion
Mll1UJ41, EPA/540/1-89/oo1, December 1989.
EPA, 1990, National Oil and HaztlTdous Substances Connngency Plan (NCP), Washington,
D.C.: Office of Emergency and Reme4ia1 Response, July 1982.
EPA, 1991a, Federal Facility Agreement and Consent Order 1088-06-29-120 in the matter of
the U.S.-Department of Energy Idtzho National Engineering Laboratory, Idaho Falls,
Idaho. December 1991.
EPA, 1991b, Health Effects Assessment SU11ZT1l(lry Tables, First Quarter, FY 1991,
January 1991, OSWER 9200.6-303.
Langford, J.E., 1971, 7RA Retention Basin StUdy, Idaho Nuclear Corporation, June 1971.
USDOE, 1992, Proposed PlalJ. For The PerchedWaler System At The Test Reactor Area, Idaho
National Engineering Laboralory, June 1992.
Orr, B.R., L.D. Cecil, and L.L. Knobel, 1991, Background Concentrations of Selected
Radionuclides, Organic Compowuls, and Chemical ConstituŁnts in the Ground Water in
the Vicintiy of the Idaho National Engineering Laboratory, USGS Water-Resources
Investigations Report 91-4015. .
.. .
.
.
.
-------
~
02~68Mi1es
I " 1 I I II
o ~ 8 12 lGometelS
.J.
Atomic City ....
Figure 1. Location of the Test Reactor Area. (TRA).
R92 0801
.-
-------
r-----------------------------------,
I n-------------------------------~ ,-I
I' ~c ]~II'
'! 0 ~. 0 !~~.
! I ~ [0] ,
I I "n7R1 0 ~ I I
I' . ~ o. I I
II ~ 11.-
I I I 1 r=---l Chemical
I I 0 III~ ~I Waste
! i i i! - ! Pond
\ i Test Reactor Area ) \ !c~~
I! \ \ ~~
I 1 ,-
I ,. Sanitary Waste
i \ (sewage) Pond
. I
I 1
I I
I I
I I
I I
.
I I
I I
I I
1 I
I I
'-----------
\
~
Warm Waste Pond
USGS WeII.s3
...'l:DZIO:m
$c8I8 in F.-
--
Figure 2. Test Reactor Area (TRA) and smrounding area.
11le date of constrUCtion is shown for the ponds.
. .
'.
-------
/. Surfaca pond
- .. &I "',. ~" \:. .J I' . .. \ r 1"\ . ,...
() . .0.'- Q , .'-, ~S~W~_wa1er~one'o
,,- "\Alluvium. I.. 1" .. 0 . ~~::":."'" "."""..."'" .. ,- 0"'". ,,:-
_Surface
50 feet
~,:~~r~&~l~i;~~
150 feet
0" 00 .' .' eO 00 ,0 00 ., ,_.. -.0" . 00" -.
'~'.C. .'~. .0. .'~. .C. "CaYenxiiiltert3ededSedimenis,u,d b~. ~~. .C. ~~. .0. .'~..
.. -. .. -. .. -. .. -. .. -. .. -. .. -. .. -. .. -. .. -. .. -0 .. -. . .
... . - ... . ... . ; '0. . ... . ... . o. ~. . 'Perching
Iayer(S)
\
'"
Basalt and I
intert>eded
sediments
.....
.~~. . V '-""~''';---.
Snake River Plain A~er::i
,.;;~~
480 feet
RII2 0740
_oc(l'latID-1
Figure 3. Generalized cross section showing a TRA wastewater disposal pond and the perched water system (PWS)
under the TRA. .
Test Reactor Area
---
-
-
./
I
If
.742.6
o
[
\
\
-\
"
"-
"
"
"
.... 0
'016.9
....
"
BoundarY of ./ "
deep perdIed zone /' - -
- - 4706.5 /
- - .77U.1 0
-- ./
--- --- - - -'"
i
- Approximate extent of deep perched water
o Deep Pen:hed WatBr WeD
o
.
500
1000
2000 FEET
.
R92 1331
Figure 4. Configuration of the deep perched ground water at TRA. Mard121. 1991-
-------
=72
o
pIN-'.
b.
~----
Test Reactor Area
USGS-ia 0
~ oUSGs.&4
~Sewage pond
USGS.7~
o
~_.,~
USGs.66
pw.u~ rL~arm waste pond
USGs.&3 U~ PW-11 USGS-70
uSG~ Cold waste ;nd
~ ooUSGS-6D
-............J pw~
usc;s.;o
USGs.7S
°
PW-'04
PW4o!,
USG5-n
PZ- 'b.
(rJ\Ao4S-1
USG$.Qo
o PW.7
USGS-7'I °
USGSoG6 0
o Petefted_er-I
A Petch8d-tweO 1nsaIIe
-------
c SITE 19
T'l'iA-Z.
aiV\-4.. ~
iMA-1
a t.rT'F„T-
Test Reactor Area
o Chemic:al wast8 pond
l22:; Sewage pond
T'FIJ,0071I
i'RM)isII C
f1, ~arm waste pond
~
~ ~ waste pond
C USG5-~ .-
a USGSo65
8'T1'1M18
1rIA-08
.
. Predudion wells USG5-76
a Sna- ~ Plain ~. well a
. SnaD RMr Plain Aqgi8( WeD insI3IIed dUring petdI8d water inYeSIi;a1ian
..
o
.
-
.-
:a» FES"
:
111'%1-
Figure 7. Locations of Snake River Plain Aquifer wells.
. .
-------
1200
1000
::J
~ 800
....
.2
e
c
g 600
c
o
o
(5
~ 400
o
I-
200
Max = 1011.7
o
1940
2140
125-yr maximum
predicted concentration
6.91~gIL
MCL 100 uaIL
1980
2020
Years
2060
2100
R!I2 ,m
Figure 8. Maximum modeled chromium concentrations in the Snake River Plain Aquifer.
~
(3
.s, . 500
c
..2-
e~.
c:400
-------
20
18
16
- 14
....J
~
~ 12
.2
C;
~ 10
CD
o
c
8 8
"0
o
6
4
2
o
1940
Max. 15.185
12S-yr maximum
predicted concentration
1.30\1g!L
MCl = 5.0 11
2100
2140
1980
2020 2060
Years
R!IZ 132. .
Figure 10. Maximum modeled cadmium concentrations in the Snake River Plain Aquifer.
. .
, .
'.
-------
Table 1.
Total and daily process water discharged to the Test Reactor Area pond system.
Total CUITmt Daily
Discharge Discharge
(gaW (gpm)b
Pond
Period of Use
Warm Wasre Pondl 1952-present 5.35 x 1<1 30-40
Retention Basin
Cold Wasre Pond 1982-present 2.13 x 109 500
Chemical Waste Pond 1962-present 7.26 x loa 15-20
Sanitary Wasre Pond 1952-present 5.35 x 1<1 15-20
Injection Well 1964-1982 3.89 X 1<1
USGS-53 . 1960-1964 2.2 X lOS
L
Total alSCharge volume from 1952 through 1990.
Daily discharge based OIl 24 homs pet" day, 7 days pu week.. Sowce: Personal COaurwnicatiOD with Bob Beatty, EG&G Idaho. IDe.,
Idaho FaDs, Idaho, 1991. The rata shown for the injection wdl aDd for USGS-53 are historical. Funher, the raICS for USGS-53 arc
only avenge values when in use. as this weJl was oDly used inIcrmiUcntly between 1960 and 1964.
b.
. .
-------
Table 2. Concentration ranges and detection frequency in the shallow perched zone.
Maximmn Minimum Quantitation Arithmetic Detection
Cone. Cone. Limit Mean- Frequency
Detected Detected
Chemical (,&g1L) (pg1L) (,&g1L) (pg1L)
. VOLATILE ORGANIC DATA
Methylene 9.0 9.0 0.5 1.7 1/6
Chloride
Benzene 0.8 0.8 0.5 0.3 1/6
Toluene 4.9 4.9 0.5 1.0 1/6
Ethylbenzene 0.7 0.7 0.5 0.3 1/6
Xylene (total) 4.0 4.0 0.5 0.9 116
Xylene (ortho) 2.0 2.0 0.5 0.5 116
1,2,4- 0.8 0.8 0.5 0.3 116
Trimethylbenzene
BEXA VALENT CHROMIUM DATA
Hexavalent 178 10.0 5.0 68.5 6/6
Chromium
SEMIVOLATJLE ORGANIC DATA
bis(2- 35.0 10.0 20.0 15.3 6/6
Ethylhexyl)phtbal
ate
NON-METAL INORGANIC DATA
Fluoride 430 90.0 70.0 180 4/6
Nitrate 6,230 1.020 100 2,690 6/6
Phosphate 2,1:10 454 100 1.320 5/6
Chloride 31,900 10.000 1.000 12,200 3/6
Silica 109.000 2,240 1,000 36,600 6/6
sulfate 4,880,000 305,000 5,000 939,000 3/6
INORGANIC DATA
Aluminum .430,000 13,000 47.0 225,000 6/6
. -
Antimony 16.6 16.6 14.0 8.4 1/6
Arsenic 42.8 5.0 3.0 21.0 6/6
. -
Barium . 10,300 567 22.0 4,900 6/6
..
:
-------
Table 2. Continued
Maximum :Minimum Quantitation Aritlunetic Detection
Cone. Cone. Limit MeaIf' Frequency
Detected Detected
Chemical ~IL) (JlgIL) (JlgIL) (JlgIL)
. INORGANIC DATA
Beryllium 136 5.0 1.0 40.1 1/6
Cadmium 177 4.0 4.0 47.5 6/6
Calcium 898,000 130,000 50.0 426,000 6/6
Chromium 4,480 32.0 9.0 1,360 6/6
Cobalt 297 26.0 20.0 131 5/6
Copper 1,930 15.0 15.0 730 6/6
Iron 546,000. 9,220 12.0 260,000 6/6
Lead 4,260 31.5 1.0 864 6/6
Magnesium 400,000 57,500 5.0 214,000 6/6
Manganese 92,000 237 3.0 19,500 6/6
Mercury 394 0.1 0.1 71.1 6/6
Nickel 6,680 22.0 14.0 1,420 5/6
Potassium 46,500 10,200 23.0 30,600 6/6
Selenium 13.8 13.8 1.0 2.7 116
Silver 70.9 3.0 3.0 23.2 5/6.
Sodium . 1,390,000 5,650 50.0 245,000 6/6
Thallium 2.5 1.6 1.0 1.8 5/6
Vanadium 764 . 57.0 7.0 431 6/6
Zinc 10,700 73.0 18.0 2,800 6/6
Maximmn Minimum Quantitation Arithmetic: Detection
Cone:. Cone. Limit Mean- Frequency
. Detected Detected
Radionudide . (pCiIL) (pCiIL) (pCiIL) (PCilL)
RADIOLOGICAL DATA (ALPHA)
U-238 2.4 x 1()4Z 1.1 x 1()'04 5.0 x lQ4S 4.1 x loe 6/6
U-234 5.2 x 1001 2.4 x lQ4Z 5.0 x 1()'04 9.2 x 10-0: 6/6
Cm-244 1.6 x 1001 5.2 x lQ4S NR 2.7 x lQ4Z 6/6 . .
.'
-------
Table 2. Continued
RADIOLOGICAL DATA (GAMMA)
Maximum Minimum Quantitation Arithmetic Detection
Cone. Co~ Limit Mean- Frequency
Detected Detected
Radionudide (pCiIL) (pCilL) (pCilL) (pCilL)
QH50 1.22 X 107 LOx 10" 2.00 x 101 1.53 x 1e>6 316
Cs-134 6.24 x 10" 1.0 x lQ2 1.00 x 101 7.83 x 1Q3 316
Cs-137 2.10 x 107 2.93 x 10" 3.00 x 101 2.63 x le>6 316
Eu-152 1.08 x lOS 6.02 x 1Q2 3.00 x 1Qi 1.37 x 10" 3/6
Eu-154 1.30 x IOS 2.35 x lQ2 4.00 x 101 1.63 x 10" 3/6
Eu-155 2.04 x 10" 2.04 x 10" 4.00 x 101 2.57 x 10' 116
Zn-65 1.05 x IOS 1.21 x 10' 3.00 x 101 1.33 x 10" 2/6
Am-241 1.67 x 10" 1.67 x 10" 5.00 x 101 2.11 x lcr 116
Mn-54 3.36 x 1Q2 3.36 x 1Q2 1.00 x 101 4.63 X 101 116
Sc-46 4.14 x 10' 4.14 x 1cr 2~00 X 101 5.26 x 10' 1/6
Cr-51 2.54xl
-------
Table 2. Continued
RADIOLOGICAL DATA (BETA)
Maximum Minimmn
Contaminated Detection Quantitation
Detected Concentration Limit
Radiooudide (pCiIL) (pCiJL) (pCiIL)
Strontium-90 18,000 3.6 1.0
Tritiuml> 2,510,000 400
Mean
(Arithmetic)
(pCiIL)
4,560
Detection
Frequency
4/6
1,850,000
L
For l1CJI1-detectC:ODCelllratious, oao-balf1he qu8DlitatiODIimit - used in ~'I.m.,g the aritlundic: mean.
The sballow perehed triIium ~ used - the peak model iDput couc:C1llr8tionobllCl'Ycd duriDg 1987 to 1990.
1>.
"
, '
"
..
, "
34
, '
. ::,. '.
..".. "
. ,". ',,:
-------
Table 3. Concentration ranges and detection frequency in the deep perched zone.
Maximmn MiDimmn Quantitation Arithmetic Detection
Cone. Cone. Limit Mean- Frequency
Detected Detected
Chemical (pg1L) (pg1L) (pg1L) (pg1L)
VOLATILE ORGANIC DATA
Methylene 1.5 0.9 0.5 0.3 2127
Chloride
Chloroform 1.1 1.1 0.5 0.3 1/27
1,1,1- 6.3 1.0 0.5 0.5 3/27
Trichloroethane
Benzene 0.8 0.8 0.5 0.3 1/21
Toluene 0.8 0.7 0.5 0.3 2121
BEXA VALENT CHROMIUM DATA
Hexavalent 160.0 5.9 5.0 31.4 4/21
auomium
SEMIVOLATILE ORGANIC DATA
bis(2- 190.0 11.0 20.0 21.3 7/27
Ethylhexyl)phtbal
ate
NON-METAL INORGANIC DATA
Fluoride 4,050 240 70.0 561 27/27
Nitrate 20,500 370 100 5,180 27/27
Phosphate 1,100 167 100 438 26/Zl
Chloride . 64,800 13,400 1,000 24.500 Zln:T
Silica . 42,300 6,410 1.000 36,600 Zln:T
Sulfate 388,000 .21.000 5,000 93.900 Zl n:T
INORGANIC DATA
Aluminum 31,600 88.0 47.0 3,820 . 24n:T
Antimony 21.7 21.7 14.0 7.8 1m
Arseuic 18.1 1.0 3.0 4.9 Z1.I27
Barium 712 52.0 22.0 165 Zln:T
. y Beryllium 8 1.0 1.0 1.3 6n:T.
Cadmium 18 4.0 4.0 3.0 6n:T
. .
"
. .
..
. ;0.-::...'.
35
. .
-------
Table 3. Continued
Maximwn
Cone.
Detected
(JLg1L)
Chemical
CalCium
Chromium
556,000
1,125
103
119,000
75.9
89,100
1,670
153
19,900
12.0
Copper
,
Iron
Lead
. Magnesium
Manganese
Nickel
Potassium
Selenium
Silver
Sodium
6.1
1,220,000
1.3
Thallium
Vanadium
75
3,180
Zinc
Quantitation
Limit
Minimwn
Cone.
Detected
(,lg1L) (pg1L)
INORGANIC DATA
66,400
13.0
26.0
158
1.0
13,600
6.0
14.0
1,870
1.4
5.7
62.0 .
1.3
9.0
15.0
50.0
9.0
15.0
12.0
1.0
5.0
3.0
14.0
23.0
1.0
3.0
50.0
1.0
7.0
18.0
RADIOLOGICAL DATA (ALPHA)
Chemical
U-238
U-234
Maximum
Cone.
Detected
(pCiJL)
8.0 x 1~
1.42 x lo-az .
Minimum
Cone.
Detected
(pCiIL)
3.5 x lam
3.5x lam
Quantitation
Limit
(pCi/L)
5.0 x 1
-------
Table 4. Federal drinking water standards and background concentrations for inorganics, organics,
and radionuclides.
. . "Federal Primary Federal Secondary
Drinking Water Drinking Water
Standard Standard
40 CPR 141.11 40 CPR 143.3 Background-
Inorganic (p.g/L) (p.g/L) (jLglL)
Arsenic' 50 2-3
&rlum 1,000 50-70
Cadmium 10 <1
Chromium 50 2-3
Chloride 250,000
Copper 1,000
Fluoride 4,000 2,000 400-500
Iron 300
Lead 50 <5
Manganese 50
Mercury 2 <0.1
Nitrate 10,000 < 1,400
pH 6.5-8.5
Selenium 10 <1
Silver 50 <1
. . " Sulfate 250, ()()()
'IDS 500,000
. .
Zinc . .- 5,000
"~ Background for Snake River Plain Aquifer in the vicinity ofINEL. (From Orr et aL 1991)
-------
Table 4. Continued
. .
Organic
Federal Primary
Drinking Water
Stancmd
40 CPR 141.12
40 CPR 141.61
(lLglL)
Volatile Organics
Benzene
Carbon
Tetrachloride
1,I-Dichloroethylene
5
5
7
1,2-Dichloroethane
para-Dichlorobenzene
Total trihalomethanes
5
75
100-
1,1,1- Trichloroethane
Trichloroethylene
Vinyl chloride
200
5
2
a. Sum of the concentrations of bromodichloromethane, dibromochloromethane,
bromoform, and" chloroform.
. ,
. .
'.
-------
Table 4. Continued
Federal Primary
. . Drinking Warer
Standard Proposed
. . 40 CFR 141.15 Drinking Warer
40 CFR 141.16 Standardc Background-
. Radionuc1ide (PCiIL) (pCiIL) (PCilL)
Total Uranium b none 20 Jl.g/l (= 30 pC ilL) 0 - 9.0
Radium 226 & 228 5 .0 (combined) 20 (each) < 5.0
Radon 222 none 300 0 - 250
Plutonium 238 none C 7J12 f 0
Plutonium 239, 240 none C 62.1 f, 62.2 f 0
Americium 241 none C 6.34 f 0
Tritium 20,000 60,900 75 - 150
Strontium 90 8.0 42 0
Iodine 129 none d 21 c 0 - .05
Gross alpha C 15 15 0 - 5
Man-made beta d 4 mremlyear 4 mremlyear 0 - 8
Cerlum137~um13~ none d 119c 0
Cobalt 60 none d 218 c 0
a. Bac1cground for SDake River Plain Aquifer in the viciIlity ofINEL (From Orr et al. 1991).
b. Total uranium is the sum ofuranium-234, uranium-235, and uramum-238.
c. The MCL for gross alpha particles is for the combined total of alpha emitters excluding radon and uranium.
d. The MCL for beta and photon sources is based on the average annual conc:entration from man-made sources. If two
or more radionuclides are present, the sum total of their annual dose equivalent to the total body or to any organ
cannot exceed 4 millliem per y~. .
e. These standards were proposed in the July 12, 1991 Federal Register (FR, v. 56. no. 138). Although chemical
specific standards were proposed for only radon-222, radium-226, radium-21S, and uranium (totaI). smndards are
also proposed to remain the same for adjusted gross alpha and beta particle and photon emitters (15 pCiIl and 4
mNmIyear, respectively). Foot-noted ~dards listed in this column for alpha and beta/photon emitters are
calculated standards listed in the Federal Register based on the entire allowable dose being committed by each
chemical alone.
, .
f. . These standards are the calen1ated concenttatioDs for each alpha emitter which would result in a lifetime cancer
. incidence risk of 1 x 1~, assuming a daily intake of2liters per day.
, .
g. These.standards are thecalen1ated coneentndions in water which would result in a dose of 4 mi11irem per year,
assoming a daily intake of 2 liters of driDk:ing water over a 50-year period. .
.'
-------
Table 5. Perched Water System contaminants of concern and deep perched zone
mean concentrations.
Contaminant A veI'3ge Concentration HaIf-Life . '
.Arsenic 4.9 p,glL
Beryllium 1.3 p,glL . .
Cadmium 3.0 p,glL
Chromium 93.5 p,glL
Cobalt 10.0 p,glL
Flouride 561 p,gIL
Lead 9.4 p,glL
Manganese 255 p,glL
Americium - 241 25.0 pCiIL 458 years
Cesium - 137 15.0 pCilL 33 years
Cobalt - 60 14.3 pCiIL 5.3 years
Strontium - 90 31.9 pCi/L 38 years
Tritium 1.15 X IOS pCi/L 12.5 years
. ,
-------
Table 6. Average concentrations of contaminants used for risk assessment and in the Perched
Water System predicted by computer model.
.
Contaminant Concentration
of used in future risk
Concern assessment
. for year 2115
Arsenic 3.20 x 10..11 ILgfL
Beryllium 5..40 x 10-12 ILgfL
Cadmium 1.30 ILgfL
Chromium 6.91 p.gfL
Cobalt 4.10 x 10-5 ILgfL
Fluoride 1.73 x 1~ ILgfL
Lead 5.02 XlO-Il p.gfL
Manganese 1.60 x 10-2 p.gfL
Amercium - 241 9.54 x 10-5 pCilL
Cesium - 137 1.17 x 10-16 pCiIL
Cobalt - 60 1.70 X 1()"2 pCiIL
. Strontium - 90 2.90 x. 10-1 pCiIL
Tritium 6.60 x 10-5 pCiIL
. ,
r .
, .
.-
, .
. .
. .
41
-------
Table 7. Summary of nonradiologica1 carcinogenic risk in year 2115.
Groundwater Crop Livestock Total
Chemical Ingestion Ingestion Ingestion Risk ' .
Arsenic 6.6 x Hrl6 7.4 x 10-19 2.5 x 10-18 6.6 X 10-16
5.1 X 10-19 '
Beryllium 2.7 x 10-16 8.2 X 10-3) 2.7 X 10-16
Lead 2.4 X 10-17 4.0 x 10-3) 1.3 X 10-3) 2.4 X 10-17 .
. ..
."
. .::.":..".,
. .". ...'"
42
-------
Table 8. Summary of radiological carcinogenic risk in YeaI 2115.
t , Groundwater
Crop Livestock Total
.. Chemical Ingestion Ingestion Ingestion Risk
Cobalt-60 5.4 x 10,9 2.8 X 10-12 2.0 X 10-10 5.6 x 1
-------
Table 9. Summary of noncarcinogenic hazard indices (child) in year 2115.
Groundwater Crop Livestock Total Hazard
. ,
Chemical Ingestion Ingestion Ingestion Index
Arsenic 2.0 x 10-12 4.6 X 10-15 1.5 x 1
-------
Table 10. Summary of noncarcinogenic hazard indices (adult) in year 2115.
Groundwater Crop Livestock Total Hazard
, . Chemical Ingestion Ingestion Ingestion Index
.- Axsenic 8.8 X 10-13 9.8 X 1()"16 3.3 X 10-15 8.8 X 10-13
~ . 8:9 x 10-18
Beryllium 3.0 x 10-14 5.5 X 10-17 3.0 X 10-14
. Cadaiium 7.1 X 10-2 8.5 X 10-5 7.3 X 10-5 7.1 X 10-2
Cobalt 3.9 x 1~ 2.1 x 1
-------
Table 11. Summary of 3O-year rolling average concentrations.
30-year Titimn Chromium Cadmium
Period . ,
1990-2020 68,000 270 10 ..
. .
1995-2025 37,000 199 10
.
2000-2030 10,000 146 9
2005-2035 3,000 104 8
2010-2040 1,000 72 6
. ,
. I
.-
- .
.. .
..
46
'.- .'"
. .
. .
-------
Table 12. Near-term excess lifetime cancer risks from tritium exposure.
> .
Risk Period lDgestion InbaJation Total
~
1990 to 2020 2 x 1O-C 9 X 10.5 3 x 1O-C
.. .
1995 to 2025 1 x lO-C 5 X 1()"5 2 x 1O-C
.
2000 to 2030 3 x 1()"5 1 X 1()"5 4 X 1()"5
2005 to 2035 9x l~ 4x l~ 1 X 1()"5
2010 to 2040 3xl~ 1 x l~ 4x 1~
.. .
t .
.-
..
-------
Table 13. Near-term hazard quotients for cadmium and total chromium.
Risk Period Cadmimn
1990 to 2020 0.6
1995 to 2025 . 0.5
2000 to 2030 0.5
2005 to 2035 0.4
2010 to 2040 0.4
Chromimn . ..
1.3 ~
1.0 ..
0.7 ~
0.5
0.4
. ~
4 ~t
.~..
'. '
, -
..
....
. -
. ,
~.
48
'.-.' ."
------- |