EPA/ROD/R10-95/120
September 1995
EPA Superfund
Record of Decision:
Idaho National Engineering Laboratory
(USDOE), Operable Unit 1-07B, Waste
Area Group 1, Idaho Falls, ID
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DECLARATION OF THE RECORD OF DECISION
Site Name and Location
Technical Support Facility Injection Well (TSF-OS) and
Surrounding Groundwater Contamination (TSF-23)-Operable Unit (aU) 1-o7B
Test Area North (TAN) Miscellaneous No Action Sites OUs 1-01, 1-02, 1-06, and 1-09
Waste Area Group 1
Idaho National Engineering Laboratory
Idaho Falls, Idaho
Statement of .Basis and Purpose
1bis decision document presents the selected final remedial action for au 1-07B [the Technical
Support Facility (TSF) Injection Well and Surrounding Groundwater Contamination] at the Idaho
National Engineering Laboratory (INEL). Also included are a group of miscellaneous sites at TAN
that were evaluated under the Track 1 process and found to require no action. These actions were
chosen in accordance with the Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA) as amended by the Superfund Amendments and Reauthorization Act and, to the extent
practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). . These
decisions are based on information in the Administrative Record for the site.
The lead agency for this decision is the U.S. Department of Energy (DOE). The U.S.
Environmental Protection Agency (EP A) approves. of this decision and along with the Idaho
Department of Health and Welfare (IDHW) has participated in the evaluation of final remedial action
alternatives. The IDHW concurs with the selected remedy.
Assessment of the Sites
Actual or threatened releases of hazardous substanCes from au 1-o7B, if not addressed -by
implementing the response action selected in this Record of Decision (ROD), may present an
imminent and substantial endangerment to human health and welfare or the enviromnent from future
use of water taken from the TSF-OS Injection Well or from new drinking water wells placed within
the plume where drinking water standards are exceeded.
The DOE has determined that no action is necessary for the TAN miscellaneous sites, which
include portions of OUs 1-01, 1-02, 1-06, and 1-09. The sites in these four OUs have been
categorized into underground storage tanks, potential soil contamination sites, and wastewater disposal
sites. This decision is based on the results of Track 1 investigations that indicated these sites do not
pose an unacceptable risk to human health. The EP A approves the DOE decision, and the IDHW
concurs.
Description of the Selected Remedy
The OU 1-07B remedy presented in this ROD is intended to reduce potential risk to human
health by reducing groundwater contamination and preventing the ingestion of cont2minMM
groundwater by future residents at this site. The contaminant~ identified at conceDtrations above risk-
based levels in the groundwater are organic compounds trichloroetbene (TCE), cis- and tranS-l,2-
dicbloroetl1ene (DCE), and tetrachloroethene (PCE), and radionuclides strontium-90, tritium,
cesium-137, and uranium-234. Operable Unit l-07B"is defined as that part of the groundwater
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beneath TAN that has, or is expected to have, concentrations of TCE above the Safe Drinking Water
maximum contamin:lnt level (MCL) of 5 p.g/L. Trichloroethene is being used as the indicator
constituent for defining the groundwater plume because it is the most widely distributed contamin:lnt
of concern (COC) in the TAN groundwater. The selected remedial action for au 1-07B is
groundwater plume extraction and treatment of the greater than 25 p.gfL TCE plume and hydraulic
containment of the TSF-05 Injection Well hotspot with aboveground treatment. The reasonable
timeframe for restoration of the aquifer to drinking water standards should not exceed 100 years. The
TSF-05 Injection Well hotspot is the subsurface area in the immediate vicinity of the injection well
containing the highest concentrations of dissolved contaminants as well as undissolved residual
contamin:lnt~. The selected remedial action will be conducted in three phases:
.
Phase A-Remove as much of the secondary source as possible from the vicinity of the
TSF-05 Injection Well by physically and hydraulically stressing the well. The treatment
system shall be designed such that concentrations of volatile organic compounds (VOCS) in
the effluent are below MCLs before reinjection into the hotspot. All attempts will be made
to operate this process as a hydraulically contained system. The air pollution control
device will be operated in compliance with applicable or relevant and appropriate
requirements (ARARs). Continue swging and stressing the well for 15 montL.. unless
Phase B is ready to begin before this date.
.
Phase B-Prevent to maximum extent practicable, migration of contaminated groundwater
beyond the hotspot at levels above MCLs, or for those contaminants for which an MCL .
does not exist, the contaminant concentration will be such that the total excess cancer risk
posed by release of contamin:lted groundwater will be within the acceptable range of 10'"
to 1()"6. For aboveground treatment processes using reinjection of treated effluent,
treatment shall, at a minimum, be sufficient to reduce the VOC concentration to below
MCLs. Volatile organic compounds discharged to the atmosphere from Groundwater
Treatment Facility (GWTF) operatbns will not exceed calculated emission rates.
.
Phase C-Capture and/or treat a sufficient portion of the dissolved phase plume beyond the
hotspot to provide for aquifer cleanup within 100 years of the date of ROD signature. For
aboveground treatment processes using reinjection of treated effluent, treatment shall be
designed to reduce the VOC concentration to below MCLs. If an MCL does not exist, the
contaminant concentration will be such. that the total excess cancer risk posed by the
groundwater will be within the acceptable range of 10-- to 1()"6. Volatile organic
compounds discharged to the atmosphere from GWTF operations will not exceed
calculated emission rates.
.
Institutional controls and groundwater monitoring-Institutional controls shall be
implemented to protect current and future users from health risks associated with ingestion
of groundwater cont:l;n;1\g cae concentrations greater than MCLs or 10-- to 1(t6
risk-based concentrations for contaminant!!: without MCLs. Institutional controls shall be
maintained until cae concentrations fall below MCLs or 10'" to 1()"6 risk-based .
concentrations for contam;nant~ without MCLs.
The purpose of Phase B is to remove, treat, or contain the contamin:lnt!!: to prevent continued
downgradient migration from the source area. Knowledge gained during implementation of both
Phase A and B will be used to determine the feasibility of removing, treating, or containing the
source area to MCLs or other risk-based standards. If cleanup of contaminants in the source area
does not appear technically practicable, a Technical Impracticability Waiver (TIW) will be pursued
for the source area. If a TIW is granted, an alternative remedial strategy to prevent migration of
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contamin:lnt~ beyond the source area will be necessary. The actions required in this ROD are not
inconsistent with foreseeable alternative remedial strategies.
Statutory "Determmation
The selected remedy for OU l-07B 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 uses permanent solutions and treatment
technologies to the maximum extent practicable and satisfies the statutory preference for remedies that
reduce toxicity, mobility, or volume as a principal element.
This action involves the injection to the aquifer of fluids with contaminant concentrations above
MCLs which may contain radionuclides. Because this remedy will result in hazardous substances
remaining onsite above Federal drinking water standards, a review will be conducted within 5 years
of commencing the remedial action, in accordance with Section 121(c) of CERCLA to ensure the
remedy continues to provide adequate protection of human health and the environment.
No further remedial actions are necessary for the portions of OUs 1-01, 1-02, 1-06, and 1-09
included in thi$ ROD to ensure protection of human health and the environment. A statutory 5-year
review will not be required, in accordance with Section 121(c) of CERCLA, because hazardous
substances do not remain on these sites.
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Signature sheet for the foregoing Record of Decision for the final remedial action for Operable
Unit 1-07B [Technical Support Facility (TSF)-05 Injection Well and Surrounding Groundwater
Contamination (TSF-23)] and Miscellaneous No Action Sites (Operable Units 1-01, 1-02, 1-06,
and 1-09) at the Test Area North at the Idaho National Engineering Laboratory between the United
States Department of Energy and the United States Environmental Protection Agency, with
concurrence by the Idaho Department of Health and Welfare.
li./6/9f
Dae
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. Signature sheet for the foregoing Record of Decision for the final remedial action for Operable
. Unit l-07B [Technical Support Facility (TSF)-05 Injection Well and Surrounding Groundwater
Contamination (TSF-23)] and Miscellaneous No Action Sites (Operable Units 1-01, 1-02, 1-06,
and 1-09) at the Test Area North at the Idaho National Engineering Laboratory between the United
States Department of Energy and the United States Environmental Protection Agency, with
concurrence by the Idaho Department of Realth and W~lfare.
~~~
Chuck Clarke
Regional Administrator, Region 10.
Environmental Protection Agency
?--IF-s-
Date
.
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Signature sheet for the foregoing Record of Decision fot the final remedial action for Operable Unit 1-07B
[Technical Support Facility (TSF)-OS Injection Well and Surrounding Groundwater Contamination (TSF-
23)] and Miscellaneous No Action Sites (Operable Units 1-01, 1-02, 1-06, and 1-09) at the Test Area
North at the Idaho National Engineering laboratory between the United States Department of Energy and
the United Sta~ Environmental Protection Agency, with concurrence by the Idaho Department of Health
and Welfare.
Wallace N. Cory
Administrator
Division of Environmental Quah
Idaho Department of Health and Welfare
'0;1 l/qS-
,
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CONTENTS
DECLARATION OF THE RECORD OF DECISION. . . . . . . . . . . . . . . . . . . . . . . . . . .. Hi
ACRONYMS and ABBREVIATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
xi
OPERABLE UNIT l-Q7B DECISION SUMMARY. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
SITE NAME, LOCATION, AND DESCRIPTION. . . . . . . . . . . . . . . . . . . . . . . . ~. 1
SITE mSTORY AND ENFORCEMENT ACTIONS. . . . . . . . . . . . . . . . . . . . . . .. 3
HIGIn.IGHTS OF COMMUNITY PARTICIPATION. . . . . . . . . . . . . . . . . . . . . . .. 5
SCOPE AND ROLE OF OPERABLE UNIT ............................. 6..
SUMMARY OF SITE CHARACTERISTICS. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
SUMMARY OF SITE RISKS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . " 17
DESCRIPTION OF ALTERNATIVES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 23 .
SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES. . . . . . . . . . " 26
SELECTED REMEDY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 31
STATUTORY DETERMINATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 40
DOCUMENTATION OF SIGNIFICANT CHANGES. . . . . . . . . .. . . . . . . . . . . .. 45
TEST AREA NORTH TRACK 1 NO ACTION SITES . . . . . . . . . . . . . . . . . . . . .. 46
APPENDIX A-RESPONSIVENESS SUMMARY. . . . . . . . . . . . . . . . . . . . . . . . . . . .. A-I
APPENDIX B-PUBUC COMMENT/RESPONSE UST ........................ B-1
APPENDIX C-ADMINISTRATIVE RECORD INDEX. . . . . . . . . . . . . . . . . . . . . . . .. C-I
FIGURES
1-1. Location of the Idaho National Engineering Laboratory and the Test Area North. . . . . . .. 2
1-2. Test Area North facilities and location of the TSF-Q5 Injection Well. """"""" 3
5-1. Water table map of the Test Area North area showing the inferred groundwater flow
direction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . .. 9
5-2. Iso-concentration map for TCE (1992 analytical data) ....................... 14
5-3. Iso-concentration map for DCE (1992 analytical data) . . . . . . . . . . . . . . . . . . . . . .. 15
5-4. Iso-concentration map for tritium (1992 analytical data) . . . . . . . . . . . . . ~ . . . . . . .. 16
9-1. Schematic of the esrim!lted sequence for OU 1-07B . . . . . . . . . . . . . . . . . . . . . . . .. 32
TABLES
5-1. Contaminants of concern and range of concentrations in the Test Area North
groundwater. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . .. 11
5-2. Results of June 1993 sampling of TSF..Q5 Injection Well and Interim Action Wells
TAN-2S and TAN-~ ........................................... 12
5-3. Validated results from March and June 1994 quarterly sampling and analysis showing the
range of contmnin:lnt concentrationS .................................. 13
6-1. Test Area North groundwater exposure pathways. . . . . . . . . . . . . . . . . . . . . . . . .. 18
6-2. Summary of risk for Test Area North groundwater. . . . . . . . . . . . . . . . . . . . . . . .. 20
8-1. Comparative Analysis of Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 27
8-2. Esrim!l~ costs associated with retJ1p~tjation alternatives (present worth) . . . . . . . . . . .. 29
8-3. Cost summary for the OU 1-07B selected alternative: . . . . . . . . . . . . . . . . . . . . . .. 30
9-1. Idaho Administrative Procedures Act (IDAPA) emission rate screening levels, air
concentration screening levels, and calculated ~sion rate limits for OU 1-o7B. . . .. . .. 34
10-1. Summary of ARARs for Alternative 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 42
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AAC
AACC
ANP
ARARs
BLM
bls
CERCLA
CFA
CFR
COC
COCA
CTF
DCE
DOE
EPA
FET
FFAlCO
FS
gpm
GWTF
HQ
IDAPA
IDHW
IET
INEL
LDR
LOFI'
MCL
NCP
O&M
OU
PCE
pCiIL
ppm
ppmw
ACRONYMS and ABBREVIATIONS
acceptable air concentration for noncarcinogens
acceptable air concentrations for carcinogens
Aircraft Nuclear Propulsion
applicable or relevant and appropriate requirements
Bureau of Land Management
below land surface
Comprehensive Environmental Response, Compensation, and Liability Act
Central Facilities Area
Code of Federal Regulations
contaminant of concern
Consent Order and Compliance Agreement
Containment Test Facility
1,2-dichloroethene
U.S. Department of Energy
U.S. Environmental Protection Agency
final engine test
. Federal Facility Agreement and "Consent Order
feasibility study
gallons per minute
Groundwater Treatment Facility
hazard quotient
Idaho Administrative Procedures Act
Idaho Department of Health and Welfare
Initial Engine Test
Idaho National Engineering Laboratory
land disposal restriction
Loss-of-Fluid Test
maximum cont~minant level
National Oil and Hazardous Substances Pollution Contingency Plan
operation and maintenance
operable ~t
tetrachloroethene
picocuries per liter
parts per million
parts per million by weight
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-
RAO
RCRA
RI
ROD
SMC
TAN
TCE
TIW
TSF
VOC
WAG
WRRTF
remedial action objective
Resource Conservation and Recovery Act
remedial investigation
Record of Decision
Specific Manufacturing Capability
Test Area North
trichloroethene (also known as trichloroethylene)
Technical Impracticability Waiver
Technical Support Facility
volatile organic compound
Waste Area Group .
Water Reactor Research Test Facility
o
.
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OPERABLE UNIT 1-07B
DECISION SUMMARY
1. SITE NAME, WCATION, AND DESCRIPTION
The Idaho National Engineering Laboratory (lNEL) is a 2,305 Ian2 (890 mi2) Federal facility
operated by the U.S. Department of Energy (DOE) and is located on the northern edge of the Eastern
Snake River Plain. Approximately 11,700 people are employed by the INEL. The nearest offsite
populations are in the cities of Terreton arid Mud Lake [19 Ian (12 mi) east]; Arco [35 Ian (22 mi)
west]; Flackfoot [61 Ian (38 mi) southeast]; Idaho Falls [79 Ian (49 mi) east]; and Pocatello [108 Ian
(67 mi) southeast).
The Test Area North (TAN) complex is located approximately 80 Ian (50 mi) northwest of
Idaho Falls in the northern portion of the INEL and extends over an area of approximately 30 Ian2
(12 mi~ (Figure 1-1). The Technical Support Facility (TSF) is centra1Iy located within TAN and
consists of several experimental and support facilities that are for conducting research and
development activities on reactor performance. The TSF covers an area of approximately 460 x
670 m (1,500 x 2,200 ft) and is surrounded by a security fence. The TSF-05 Injection Well is
located in the southwest comer of TSF (Figure 1-2). Three other major test facilities are located near
TSF and are considered part of TAN. These facilities are the Specific Manufacturing Capability
(SMC:)/ Containment Test Facility (CTF) (formerly the Loss-of-Fluid Test (WFT) Facility, the Initial
Engine Test (lET) Facility, and the Water Reactor Research Test Facility (WRRTF) (Figure 1-2).
Current land use at the INEL is primarily nuclear research and development and waste
management. Surrounding areas are managed by the Bureau of Land Management for multipurpose
use. The developed area within the INEL is surrounded by a 1,295 Ian2 (500 mi~ buffer zone used
for cattle and sheep grazing.
The INEL has semidesert characteristics with hot summers and cold winters. Normal annual
precipitation is 23 em (9.1 in.) per year, with estim~tM evapotranspiration of 15 to 23 em (6 to 9 in.)
per year. The Big Lost River and Birch Creek are the only natural surface water features present
near TAN. TAN is located between the terminus of the Big Lost River and the terminus of Birch
Creek. Because of irrigation and hydropower diversions and infiltration losses, stream flows in the
Big Lost River and Birch Creek are typically depleteC' before reaching the INEL. Surface water can
occur at TAN during and following periods of heavy rainfall and snowmelt, which generally takes
place between January and April. However, the presence of diversion systems, and playas located at
the terminal points of the Big Lost River and Birch Creek, typically prevent surface water from
reaching TAN.
Twenty distinctive vegetative cover types have been identified at the INEL. Big sagebrush is the
dominant species on the INEL. The variety of habitats on the INEL support numerous species of
reptiles, birds, and m~mm~1~. Several bird species at the INEL that warrant special concern because
of sensitivity to disturbance or their threatened status. These species include the ferruginous hawk
(Buteo regalis), bald eagle (Haliaeet1lS leucocephalus), long-billed curlew (Numenius ameriCQ1UlS),
and the loggerhead shrike (Lanius ludovicillruls). In addition, the Townsend's big-eared bat (Plecotus
townsendil), and pygmy rabbit (Brachylagus idahoensis) are listed by the U.S. Fish and Wildlife
Service as carididate species for consideration as threatened or P-nd~neered species. The ri~eck
snake, whose occurrence is considered to be INEL-wide, is listed by - the Idaho Department of Fish
and Game as a Category C sensitive species. -"
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,
'----\ .
Test
Area
North
BIg Scxdhem auire~
RED 0233
,.
INEL
TERRETON
l~
o 2 4 6 8 MILES
I I I I I
J I I
o 4 8 12 KILOMETERS
To Idaho Falls
Figure, -1. Location of the Idaho National Engineering Laboratory and the Test Area North.
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lET
SMC/CTF (LOFT)
True
1
T AN-2 production well
T AN-1 prOduction well
TAN disposal ..~~
pond
TSF-05 injection well
ID33
To Rexburg, Terreton
and Idaho Falls
Scale
3.000 ft
WRRTF
RED 0604
Figure 1-2. Test Area North facilities and location of the TSF-05 Injection Well.
2. SITE BISTORY AND ENFORCEMENT ACTIONS
2.1 Site History
Operations at TAN were initi3ted in the early 19508 to support the U.S. Air Force aircraft
nuclear propulsion (ANP) project. The objectives of the ANP project were to develop and test
various designs for nuclear-powered engines and fuels for use on aircraft. Four facilities were built at
TAN including the TSF, lET, Low Power Test FacilitylExperimental Beryllium Oxide Reactor (now
WRRTF), and LOFI' (now the SMC/CI'F).
The principal source of groundwater cont~min~tion at TAN is the TSF-oslnjection Well located
in the southwest comer of TSF (see Figure 1-2). The TSF-05 Injection Well was used from 1953 to
1972 to dispose of TAN liquid wastes into the fractured basalt of the Snake River Plain Aquifer.
These wastes included organic, inorganic, and low-level radioactive wastewaters added to industrial
and sanitary wastewater. Activities generating these wastes included efforts to develop a nuclear-
powered aircraft and tests sintnlflti"& accidents involving the loss of coolant from nuclear reactors.
, .
Releases to TAN groundwater were first identified in 1987 when low levels of the organic
compounds tricbloroethene (TCE) and tetrachloroetheae (PCE) were detected in the production wells
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that supply drinking water to TSF. To mitigate potential risks to personnel at TAN, an air sparging
system was installed on the ~g water supply system. Subsequent sampling of TAN aquifer
monitoring wells confirmed the presence of organic compounds TCE, PCE, and 1,2-dichloroethene
(DCE), and the radionuclides tritium (H-3), strontium-90 (Sr-90), cesium-137 (Cs-137), and
uranium-234 (U-234) as contaminants above risk-:based concentrations. Only organic compounds that
are removed by the air sparging system have been consistently detected in the production wells at
levels exceeding Federal drinking water standards. Strontium-9O has been detected above d~mng
water standards. in production wells on two occasions; however, these data are suspect because
subsequent sampling has not found elevated Sr-90 levels.
In 1990, an initial effon removed process sludge from the bottom 17 m (55 ft) of the TSF-OS
Injection Well. Analytical results showed that the sludge contained high levels of organic
C011tamin:mts (2 % TCE) and radionuclides.
2.2 Enforcement
The TSF-OS Injection Well and the groundwater C011tamination at TAN were first identified and
evaluated in accordance with the ~esource Conservation and Recovery Act (RCRA) Corrective Action
Requirements of the July 1987 Consent Order and Compliance Agreement (COCA) signed by DOE,
the U.S. Environmental Protection Agency (EPA), and the U.S. Geological Survey. The COCA
required DOE to conduct an initial assessment and screening of all solid waste and/or hazardous waste.
disposal units at the INEL, which resulted in the RCRA Corrective Action Program being
implemented for the TAN groundwater.
On July 14, 1989, the INEL was proposed for listing on the National Priorities. List (54 Federal
Register 29820). The listing was proposed by the EPA under the authorities granted EPA by the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980,
40 Code of Federal Regulations (CPR) 300.42S(b)(3), as amended by the Superfund Amendments and
Reauthorization Act of 1986. The final ruling listing the INEL on the National Priorities List was
published on November 21, 1989 (54 Federal Register 44184).
As a result of the INEL being listed on the National Priorities List, DOE, EPA, and the Idaho
Department of Health and Welfare (IDHW) entered into a Federal Facility Agreement and Consent
Order (FFAlCO), pursuant to CERCLA, in December 1991. The FFAICO superseded the COCA
and established a procedural framework for agency coordination and a schedule for all CERCLA
activities conducted at the INEL.
At the TAN groundwater release site, pursuant to the FF AICO Action Plan, DOE implemented
an Interim Action and a remedial investigation (RI)/feasibility stuJy (FS) to characterize the extent of
contamination, to estimate human health and environmental risks, and to evaluate potential response
actions. The Interim Action and RIlFS, designated as Operable Unit (OU) 1-07A and 1-018,
respectively, are parallel but separate actions.
In September 1992 the Interim Action Record of Decision (ROD) was signed. The objectives
of the Interim Action were to reduce contaminant levels near the TSF-OS Injection Well and in the
surrounding groundwater, and to measure aquifer parameters based on data from groundwater
extraction and new monitoring wells. The major components of the au 1-07A Interim Action
included
"
,
.
Extracting contamin!lltM groundwater from TSF-05 Injection Well and nearby groundwater
monitoring wells capable of capturing cont~in!lltPd groundwater.
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..
.
Installing an onsite Groundwater Treatment Facility (GWTF) to reduce contaminants of
concern (COCs) in the extracted groundwater to prescribed performance standards. The
selected treatment was air stripping, carbon adsorption, and ion exchange.
.
Installing two groundwater monitoring wells within the contaminant plume to monitor the
effectiveness of the Interim Action. These wells can also be used as extraction wel'c:: to
expedite the removal of contaminated groundwater.
.
Monitoring the groundwater contaminant plume and the extraction/treatment system during
groundwater extraction activities to track effectiveness of the system and ensure
performance standards are achieved. .
.
Modifying the existing TAN disposal pond to receive the treated groundwater and ensure
discharge water quality does not further degrade the underlying Snake River Plain Aquifer
above maximum contaminant levels (MCLs). The pond was modified by constructing a
berm to separate the western one-third of the pond from the remaining two-thirds. Treated
groundwater from Interim Action activities was discharged to the western one-third.
.
Implementing administrative and institutional controls to supplement engineering controls
and minimi7.e exposure to releases of hazardous substances during remediation.
The purpose of this ROD is to document the final remedial action for OU l-Q7B.
3. mGHLIGBTS OF COMMUNITY PARTICIPATION'
In accordance with CERCLA Sections 113(k)(2)(B)(i-v) and 117, community interviews were
conducted with local officials, community residents, and public interest groups to solicit concerns and
information needs and to learn how and when citizens would like to be involved in the CERCLA
process. The information gathered during the community interviews and other relevant information
provided the basis for development of the INEL-wide COmmunity Relations Plan. This INEL-wide
Community Relations Plan will continue to be implemented during this final response action to reflect
the decisionmaJcil1g process under CERCLA and the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP) (40 CFR Part 3(0) and to ensure that appropriate public participation
continues under the FF AlCO.
The presence of organic compounds in the groundwater at the TAN was first announced in a
news release issued in November 1987. A second news release issued in September 1988 announced
both the provision of an alternate source of drinking water for workers at TAN and the scheduled
installation of an air sparging system to remove volatile organic compounds (V0Cs) from the drinking
water supply.
In accordance with CERCLA Sections 113(k)(2)(B)(i-v) and 117, the public was given the
opportunity to participate in the remedy selection process.
The Notice of Availability for the proposed plan was published in April 1994 in the following
newspapers: The Post Register (Idaho Falls), The Idaho Sttlte JoUT1lJll (Pocatello), Twin Falls limes
News (Twin Falls), Idaho Sttltesman (Boise), The Lewiston Morning Tribune, (Lewiston) Idaho Free
Press (Nampa), South IdIlho Press (Burley), and Moscow-Pullman Daily News (Moscow).
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These advertisements identified public meeting locations and times. Personal phone calls were
made to inform individuals and groups about the comment opportunity. The public was provided
with copi~ of the proposed plan via a "Dear Citizen" letter transmitted to 5,600 groups and
individuals on the mailing list.
The public comment period was scheduled from May 18 to June 18, 1994. Three public
meetings were held on June 6, 8, and 9, 1994, in Idaho Falls, Boise, and Moscow. Representatives
from the DOE, EPA, and IDHW were present at the public meetings in Idaho Falls and Boise to
discuss the proposed plan, answer questions, and receive both written and oral public comments.
Representatives from the DOE and IDHW were present at the public meetings in Moscow. For one
half-hour before each meeting, representatives from the agencies were also available for informal
discussions with the interested public. A court reporter was present at each meeting to record,
verbatim, the proceedings. Copies of the transcripts from the public meetings are available for public
review in the Infonnation Repositories (which are located at the public libraries in Boise, Twin Falls,
Pocatello, and Idaho Falls and the University of Idaho Library in Moscow) as part of the
Administrative Record for this final response action.
A Responsiveness Summary has been prep.lred to address public comments as part .Jf this ROD.
All verbal comments given at the public meetings and all submitted written comments are repeated,
verbatim, in the Administrative Record for the ROD. Those comments are annotated to indicate
which response in the RespOnsiveness Summary addresses each comment.
A fact sheet was sent to the public in January 1995 to provide citizens with updated information
on the TSF-05 Interim Action and subsequent impacts to the preferred alternative selected for
OU 1-07B.
In accordance with CERCLA Section 113(k)(1), an Administrative Record was established to
provide the basis for selection of the remedial action. The Administrative Record is availaele for
public review at the DOE Public Reading Room located at the INEL Technical Library in Idaho Falls.
Copies of the Administrative Record are available for public review at the public libraries at Boise,
Idaho Falls, Pocatello, Twin Falls, an~ the University of Idaho Library in Moscow.
Persons on the mailing list will receive a notice of availability stating the signed ROD is
available. Copies of the ROD and the Responsiveness Summary will be placed in the Administrative
Record and in the information repositories, and will be provided to the public upon request.
4. SCOPE AND ROLE OF OPERABLE UNIT
To better manage the investigations needed to determine appropriate remedial actions, the INEL
has been divided into 10 Waste Area Groups (WAGs). Within each WAG, known or suspected areas
of contamination are assigned to an OU as a means of controlling investigation and cleanup activity.
This strategy allows the EPA, IDHW, and DOE to focus available cleanup resources on those areas
that could potentially pose a risk to human health and the environment. The TAN complex,
designated as WAG 1, consists of 11 OUs. The Interim Action has been designated OU l-07A.. The
groundwater in the immediate vicinity of TAN, which bas TCE concentrations greater than the MCL
of 5 micrograms per liter (jlglL), has been desig11"ted OU 1-07B.
Sufficient characterization data are available to identify OU 1-07B as a potential risk to human
health and the environment because of the excess presence of organic contamina11t$ including TCE,
PCE, and DCE and several radionuclides including Sr-9O, Cs-137, U-234, and H-3 in the
" -
-------
groundwater underlying TAN. This final response action is intended to ensure that offsite populations
and potential future onsite residents will not be at risk.
5. SUMMARY OF SITE CHARACTERISTICS
5.1 Geology
The subsurface geology of TAN is characterized by basalt flows with sedimentary interbeds,
overlain by fine-grained sediments. Geologic descriptions from wells drilled in the TAN area indicate
that the basalt is highly variable, from dense to highly vesicular basalt and from massive to highly
fractured basalt. Individual flow units have a median thickness of approximately 4.5 m (15 ft). The
sedimentary interbeds at TAN have a median thickness of approximately 1.2 m (4 ft) and are thinner
than interbeds found elsewhere on the INEL.
There are two main interbeds in the TAN area. The P-Q and Q-R interbeds both consist of clay
or silt. Because interbed sediments at TAN are comprised mostly of fine-grained materials with low
permeabilities and high ab;)orption capacities, their presence within the basalt section is important with
respect to retarding contaminant migration.
The P-Q interbed, located approximately 61 m (200 ft) below land surface (bls) near the TSF~5
Injection Well, has been encountered in only about 50% of the wells drilled deep enough at TANto
show the interbed; therefore, it appears to be laterally discontinuous. The range of thickness of the
P-Q interbed (when present) appears to be approximately 1 to 4 m (3 to 14 ft).
The Q-R interbed. located at approximately 134 m (440 ft) bls near the TSF~5 Injection Well,
is considered laterally continuous throughout the TAN region. This is supported by (a) geological
data obtained during borehole drilling, (b) basalt flowage dates from above and below the interbed, .
and (c) hydraulic head measurements collected from wells during both sampling and TAN production
well pumping. Ten wells have been drilled deep enough to encounter the Q-R interbed at TAN. In
all 10 cases, the interbed was encountered. Basalt flows above and below the interbed show a large
age difference. The 1.3-million year hiatus between basalt flows could have provided sufficient time
for a relatively thick, laterally continuous sedimeT1tary interbed to be deposited. Borehole data
indicates that the total thickness of the Q-R interbed is approximately 12 m (40 ft). Hydraulic head
data collected from wells completed both above and below the Q-R interbed also support the
interpretation that the interbed is laterally continuous at TAN. Water level measurements were
collected during sampling and TAN production well pumping. During these events, hydraulic head
changes were noted in wells completed above the Q-R interbed but not in adjacent wells completed
below the interbed. The geological and hydrological data collected thus far suggest that the Q-R
interbed is continuous and impedes the vertical movement of water and CODtaminant!; in the aquifer.
5.2 Hydrology
The Snake River Plain Aquifer, one of the largest and most productive groundwater resources in
the United States, underlies the INEL. The aquifer is listed as a Class I aquifer, and EPA has
designated it as a sole source aquifer. The Snake River Plain Aquifer is defined as the series of
saturated basalt flows and interlayered pyroclastic and sP.dimP-ntary materials UDderlyiDg the eastern
Snake River Plain. The aquifer is approximately 325 k:m (200 mi) long, 6S to 9S k:m (40 to 60 mi)
wide, and covers an area of approximately 25,000 k:m2 (9,600 miZ). As much as 2.5 X 1012 ~
(2 billion acre . ft) of water may be stored in the aquifer---approximately 6.2 x 1011 ~.
-------
(500 million acre. ft) of which are recoverable. The aquifer discharges approximately 8.8 x 109 m3
(7.1 million acre. ft) of water annually to springs and rivers. .
The regional flow of the Snake River Plain Aquifer is to the south-southwest; locally, the
direction of groundwater flow is affected by recharge' from rivers, surface water spreading areas,
pumping of the aquifer, and heterogeneities in the aquifer. Figure 5-1 is a regional water table map
of the TAN area showing the inferred 1irection of groundwater flow. The hydraulic gradient for the
regional aquifer in the vicinity of TAN is about 0.2 milan (1 ft/mi). A major feature that should be
noted in Figure 5-1 is that the regional water-table gradient is very flat in the TAN area, which could
be the result of high transmissivity. Under the conditions of a flat water-table gradient, the influence
of the production wells on the contaminant source (TSF-D5 Injection Well) is strong and may cause
major flow disruptions or times of flow reversal within the aquifer in the vicinity of TAN. The
average depth to water at TAN is approximately 61 m (200 ft).
There are five production wells at TAN that provide groundwater for drinking, industrial, and
other facility uses (e.g., lawn watering, fire protection). Two wells [final engine test (FET)-1 and
FET-2] are located near LOFT, west of the TSF, and are outside of the au I-D7B groundwater
contaminant plume. The production wells T AN-I and T AN-2 are located on the north side of T JF
and supply water for operations at TSF. Low levels (1-8 p.glL) of TCE have been detected in wells
TAN-l and TAN-2. The fifth production well (ANP-8) is located at WRRTF, southeast of TSF.
Low levels of volatile organics have also been detected in this well.
5.3 Nature and Extent of Contamin9tion
Information from characterization activities at TAN suggests that potential airborne, sUrficial,
and vadose zone sources of contamination to the groundwater are probably insignificant contributors
to the groundwater contamination at TAN. Of the potential surface and vadose zone sources that
could have been expected to have received TCE and related volatile organics, an evaluation of waste
generation and disposal practices, and enviroDmP-11tal characterization data showed no contamination
and no sign of contaminant migration that could be related to the TAN groundwater contamination.
The only other possible sources of groundwater contamination are three injection wells. These
injection wells include the WRRTF-D5 Injection Well, the IET-06 Injection Well, and the TSF-05
Injection Well. These three possible sources have been investigated, and the available evidence
suggests that the TSF-05 Injection Well is the source of contaminauon to the groundwater at TAN. A
detailed evaluation of these and other potential sources of contamination can be found in the RI report
Remedial Investigation FiMl Repon with Addenda for the Test Area Nonh Groundwater Operable
Unit 1~7B at the IdJlho NatioMl Engineering lAboratory, Volume 1, EGG-ER-10643, January 1994,
which is located in the Administrative Record.
The TSF-OS Injection Well was drilled in 1953 to a depth of 93 m (310 ft) to dispose of liquid
eft1uent generated from the ANP project. The TSF-OS Injection Well has a 3O-cm (12-in.) diameter
casing to 93 m (310 ft) and is perforated from 55 to 74 m (180 to 244 ft) and 82 to 93 m
(269 to 305ft) bIs. The depth to groundwater is about 63 m (206 ft) bIs. The well was last used as a
disposal site in September 1972, after which wastewaters were diverted to the TAN disposal pond.
Discharges to the well included organic sludges, treated sanitary sewage, process wastewaters,
and low-level radioactive waste streams. Historical records provide little definitive information on the
types and volumes of organic wastes disposed via the injection well. It is estimated that as little as
1,325 L (350 gal) and as much as 97,161 L (25,670 gal) of TCE were disposed in the well during its
period of operation. An evaluation of the solvent usage at TAN concluded that the waste discharged
-------
. Well location
P&w.,
.
P&W.2
.
USGS-2S
.
ANP.S
.
Test Area
North
o
2,500
I
Scale (ft)
5,000
..J
RED 0605
Figure 5-1. Water table map of the Test Area North area showing the inferred groundwater flow
direction (December 19ro).
-------
to the aquifer through the injection well was not a listed hazardous waste because the organic
chemicals in the waste were not used as solvents and disposal practices were not documented.
On the basis of results from groundwater quality analyses from the injection well, as well as
analytical and radiological analysis of sediment/sludge removed from the well in 1990, the TSF-05
Injection Well is considered the major source of groundwater contamination at TAN. Since 1988,
TCE and other VOCs and radionuc1ides have been detected as a result of several sampling efforts by
the U.S. Geological Survey and DOE. Groundwater quality data from sampling events performed
between 1988 and 1991 showed TCE concentrations at the TSF-05 wellhead from 4,100 to
28,000 p.glL.
New groundwater monitoring wells were installed, and new and existing wells were sampled as
part of the RI conducted in 1992. As a result of this investigative effort, the horizontal and vertical
extent of groundwater contamination was delineated. Extensive drilling, aquifer testing, and sampling
sUggests that the majority of contamination is limited to the uppermost portion of the aquifer
underlying TAN, and that the Q-R interbed represents a hydrologic barrier that separates the upper
aquifer above the Q-R interbed from lower aquifers and influences the migration and distribution of
contaminants. Two groundwater monitoring wells were installed below the Q-R interbed as part of
the 1992 RI. One well is located within the TSF, approximately halfway between the TSF-05
Injection Well and the TAN production wells. The second well is located approximately halfway
between the TSF and the WRRTF. Only low concentrations (less than MCLs) ofVOCs were
measured below the Q-R interbed. Trichloroethene concentrations in groundwater samples collected
from the TSF-05 Injection Well during the 1992 RI ranged from 4,100 to 8,300 p.g/L.
Estimates of the amount of TCE dissolved in the groundwater account for only a small amount
of the TCE potentially disposed to the TSF-05 Injection Well. This and other evidence
(e.g., groundwater concentrations of TCE at the injection well) suggest that a secondary or residual
source of undissolved contaminants is very likely present in the vicinity of the TSF-05 Injection Well.
In this document, the term secondary source is used to indicate the presence of one or all of the
following: (a) sludge-entrained TCE, (b) water-sludge- TCE emulsions, and/or (c) free nonaqueous
phase liquids or small pools (residual saturation) in dead-end fractures or on basalt flowtops. The
TSF-OS hotspot is defined as including the secondary source and highly COlWlminated groundwater
(Le., with TCE concentrations greater than 5,000 p.g/L) in the immediate vicinity of the TSF-05
Injection Well. Evidence does not support the existence of a free phase dense nonaqueous phase
liquid.
Table 5-1 shows the concentration ranges of the COCS for OU 1-07B based on 1992 RI
groundwater sampling, and Figures 5-2, 5-3, and 5-4 show the distribution of TCE, DCE, and H-3
within the groundwater at TAN. Distribution maps were not included for PCE, Cs-137, Sr-90, and
U-234 because the distribution of these contaminant~ is mainly limited to the area in the immediate
vicinity of the TSF-OS Injection Well. A full description of contaminant concentrations in aquifer
monitoring wells and the contaminant distributions can be found in the RI report.
Analytical results from groundwater samples collected from the Interim Action monitoring wells
TAN-25 and TAN-26 [7.6 and 15.2 m (25 and 50 ft) from TSF-05, respectively] and the TSF-OS
Injection Well in June 1993 (Table 5-2) showed TCE (290-17,000 p.glL), DCE (180-9,300 p.g/L),
Cs-137 pess than the detection limit-2,030 picocuries per liter (pCiIL)], U-234 (17 pCiIL), and Sr-90
(8.2-630 pCiIL), and PCB (5-39 p.g/L). In general, analytical results from the June 1993 sampling
event are similar to those found during the 1992 RI (Table 5-1) for the TSF-05 Injection Well.
-------
Table 5-1. Cont;tminants of concern and range of concentrations in the Test Area North
groundwater. a
TAN TAN TSF.{)5
Chp.mical monitoring wells prorluction wells Injection Well MCV
PCE <1..m <1-3 <500= 5
TCE < 1-1,400 < 1-16 4,100-8,300 5
cis-l,2-DCE < 1-38 <1 5,600-5,800 70
trans-l,2-DCE <1-7 <1 3,200-3,400 100
Sr-90 < 1-470 <1-4 610-640 8
H-3 <500-9,800 420 14,700-15,800 20,000
Cs-137 <30-32 <30 1,940-2,240 119
U-234 <1 <1 5-7 30
a. Concentration ranges were derived from 1992 RI aualytica.l results; < indicates less than detection limit.
b. MCL = maximum C01l12min:.nt level per Federal drinking water SWldards. The proposed MCL for U-234 is for the
U-234, -235. and -238 series. The proposed MCL for Cs-137 is derived from a corresponding 4 mremlyr effective dose
equivalent to the public. assuming lifetime intake of 2 Uday of water.
c. A dilution factor of 500 was used during sample analysis. raising the detection limit for PCE to 500 p.glL. More recent
sampling (June 1993) used a lower detection limit (see Table 5-2).
-------
Table 5-2. Results of June 1993 sampling of TSF-05 Injection Well and Interim Action Wells
TAN-25 and TAN-26.
Chemical
TSF-05
Injection Well
TAN-25
Monitoring Well
TAN-26
Monitoring
Well
MCLa
._~::_;.:..).:. ............
~E' 20-22
TCE 5,900-11 ,OOO]b
.,.....
...,..
......
..o, ..
.......
."."
......,
.... .
.......
;':'.';':':'"','..;.;.:.'';';
-,...,
,... ..
39
17,000
Sr-90 520-630 380 8.2-8.6 8
H-3 18,700-18,800 14,200 4,700-4,800 20,000
Cs-137 2,010-2,030 147 <3OC 119
U-234 17 10 2.3-3.4 30
a. MCL = maximum contamin::mt level per Federal drinking water standards. The proposed MCL for
U-234 is for the U-234, -235, and -238 series. The proposed MCL for Cs-137 is derived from a
corresponding 4 mremlyr effective dose equivalent to the public, assuming lifetime intake of 2 Uday of
water.
b. The "1" validation flag indicates that the analyte was positively identified in the sample, but the
associated value is only an estimate of the amount actually present in the environmental sample.
c. < indicates less than detection limit.
-------
Table 5-3. Validated results from March and June 1994 quarterly sampling and analysis showing the
range of contaminant concentrations. a . .
Contaminant
TSF-05
Injection Well
............ .
_~:Iggmll.:.~
PCE
TCE
cis-1,2-DCE
trans-l,2-DCE
110
12,000-32,000
3,200-7,500
1,300-3,900
Oil and grease (mgIL)
<5-10
T AN-25
Monitoring Well
... .....
<200c
5,900-9,300
890-3,500
450-2,000
< 5-7.1
T AN-26
Monitoring Well
MCLb
,......
. .. . . . . . . . . . . . . . .
'.",',',",",",',',",',',','."""
:.:.:.:-;.:.:.: '.:.::.:.:-:.:-:
..,'... ......
'"''''
".............
".,",
. ....
..."'"
""""
.....-.....
14-19
710-1,000
230-420
5
5
70
100
17-33
< 5-46.3d
None
Strontium-9{}C
Tritium
530-1,880
14,900-15,300
5.2-7.7
<0.2
Uranium-234
Uranium-235
Uranium-238
Americium-241I
Plutonium-238
<0.1-0.43
<0.2
Plutonium-239/240
Cesium-137
<0.2
1,600-2,150
23
Cobalt-60
0.64 . 1.4
<0.2 <0.2
<0.2 <0.2
90-300 <30
<20 <20
380-440
7,500-10,000
7
a. Key: - = not sampled; < indicates less than detection limit.
2-4
3,500-3,700
1.7
8
20,000
30
30
30
None
None
119
lW
b. MCL = maximum. contaminant level per Federal drinking water standards. The proposed MCL for U-234
is for the U-234, -235, and -238 series. The proposed MCL for Cs-137 is derived from a corresponding.
4 mremlyr effective dose equivalent to the public, assuming lifetime intake of 2 Uday of water.
c. Dilution factors of 1,000 and 200 were used during the March and June sample analysis, respectively.
These dilution factors raised the detection limit for PCE to 1,000 p.gIL for the March 1994 analysis and
200 p.gIL for the June 1994 analysis. .
e. Range includes only unfiltered Sr-90 samples.
d. A duplicate sample of the 46.3 was taken, which was <5 mgIL.
f. EPA (1977), Primary Drinking Water Standard.
-------
~
.
Test Area North
T
o
TSF-05 Injection Well (avg-6,200)
TAN-2 (3)-Production Well
TAN-1 (16)-production Well
5,000
1,000
500
~
Scale
3,000 ft
o
RED 0789
Rgure 5-2. Iso-concentration map for TCE (1992 analytical data). Note: Well locations have been
corrected from the iso-concentration map presented in the OU 1-07B RI and FS reports.
.,
""
-------
f"
Test Area North
"
1
o
T AN-2 (ND)-production Well
TAN-1 (O.2)-production Well
5,000
500
o
.
@
o
Scale
3,000 It
o (II)
c:::F ~RTF
o e::o
o
RED 0790
'"
Rgure 5-3. Is
-------
..
~
Test Area North
f
"
o
TAN-2 (ND)-Production Well
T AN-1 (ND)-production Well
o
@
~
o
Scale
3,000 ft
o aD
c:::r ~RTF
o l!J:J
o
RED 0558
Figure 5-4. Iso-concenttation map for tritium (1992 analytical data). Note: Well locations have
been corrected from the iso-concentration map presented in the OU 1-07B RI and FS reports.
.,
"'"
-------
Analytical results from groundwater samples collected for the first and second quarters of 1994
for TAN-2S, TAN-26, and the TSF..{)S Injection Well during the OU 1..{)7A Interim Action are
presented in Table S-3. Upon comparison of ~ntaminant concenttations detected in wells TSF-OS,
TAN-2S, and TAN-26, it is apparent that the 1992 RI, June 1993, and quarterly Interim Action
results are generally consistent. However, it should be noted that contaminant concentrations detected
during the Interim Action have vanptj depending on pumping rate.
6. SUMMARY OF SITE RISKS
A baseline risk assessment was conducted to evaluate the potential adverse health effects for both
a current and future land use scenario to human and nonhuman receptors associated with exposure to
chemical and radioactive substances detected in the TAN groundwater. The baseline risk assessment
consists of a human health risk assessment and an ecological assessment.
6.1 Hmnan Health Risk
6.1.1 Contamin~nh: of ~oncern
In order to focus the risk assessment on COCs, the groundwater quality data collected during the
RI were evaluated against analytical methods, quantitation limits, qualified and coded data, sample
blank contamination, natural background elements, essential nutrients, and risk-based concentrations
in a systematic manner according to guidance from both EP A and EP A Region 10. .
The COCS and their concentration ranges for the groundwater sampled in the iminediate vicinity
of the TSF-OS Injection Well and the groundwater plume are listed in Table S-I. The COCS list for
the TAN groundwater plume include TCE, PCB, cis- and trans-l,2-DCE, Sr-90, and H-3. The same
COCs were identified for the TSF-OS Injection Well with the addition of the radionuclides Cs-137 and
U-234. Although U-234 and H-3 do not exceed the MCLs, these contamin:lnt~ exceed the 1~
risk-based concentration for groundwater ingestion. Tetrachloroethene was not detected above the
detection limit of SOO p.gIL in the TSF-OS Injection Well during 1992 sampling. However, it is
considered a COC based on 1989 and 1993 data. The 1993 sampling showed PCB at a concentration
of 20-22 p.gIL in the TSF-OS Injection Well. Therefore, the final COC list includes TCE, PCE,
cis-l,2-DCE, trans-l,2-DCE, H-3, Sr-90, U-234, and Cs-137 (see Table 5-1). Any additional
contamina~ detected during the OU 1-078 Remedial Action will be evaluated by the agencies for
inclusion as COCs.
6.1.2 Exposure AsPcmnmt
The exposure assessment is used to estimate the type and magnitude of exposures to the COCS
identified for the TAN groundwater and the TSF-OS Injection Well. The exposure assessment
involves identifying potentially exposed populations and exposure pathways, estimating exposure
concentrations (based on enviromnental monitoring data and fate and transport modeling), and
estimatiT1g contaminant intakes for exposure pathways. The result of the exposure assessment
eshm!:ltes the pathway-specific intakes for both current and future exposures for the identified COCS.
The potentially exposed populations identified for this risk assessment include site workers and future
residents that may inhabit the site if DOE decides to relinquish control of the site.
Current access to the TAN groundwater is limited to production wells (TAN-I, TAN-2, ANP-8,
FET-l, and FET-2), which bring the groundwater to the suiface for drinking water and other uses
such as lawn watering and industrial use. Untreated groundwater is not released to any natural
-------
surface water body in the study area and is not available for direct uptake by plants or animals;
therefore, these pathways are not evaluated in the current industrial use scenario. The current land
use sce~o evaluates the industrial use of groundwater from the production wells. Drinking water at
TAN is obtained exclusively from bottled water or the TAN production well. Treatment using an air
sparger before use reduces contaminant concentrations below Federal drinking water standards for the
TAN production wells. However, for this risk assessment it was assumed that the air sparger was not
present.
The future residential use scenario assumes three different time periods of institutional control.
The assumed institutional control periods will last until the years 2024,2040, or 2094 and are based
on different expected lengths of time for programs at TAN to be operational, in addition to time to
perform decontamination and decommissioning of the facilities in compliance with 10 CFR 61. The
future residential use scenario consists of two different future land use cases. Case 1 is the use of the
groundwater from the predicted average concentration for the contamina"t plume. Case 2 considered
the TSF-oS Injection Well as a potential future production well for residents. Although this is an
unlikely scenario, it provides an upper bOund for potential risks to residents should they be exposed to
groundwater from this well. A summary of the TAN groundwater risk assessment exposure pathways
is presented in Table 6-1.
Table 6-1. Test Area North groundwater exposure pathways.
Potentially exposed
population
Exposure scenario
Potential exposure
pathway
CI1iiim.:::'::..::..:..":::::.:...':'i.':.:.':'i.{.::::::'."::.:Ian."'.::::'.'.':::':.:':1:":'.::'.::':'...:.Jose:':.::.:'::.:':::':::':'.:.'::..:::::!:.:..:::.::'.....:...:'.!:i:::..':':':.::.i!:::'...:.:.:.'.:.'.:.:.!.:..:.:.,:"'" .. .;::':::::tt;::::;:::'/?;"::.:.::':'\{!:/'!:j::':':::::::::;::'::i::/!:!,!::!,:::!:,:@t:: ::m:I:,':'::::@@!;:i:"tW:!;:i::/.,ii=:::;:,............
":"':-:':':':';':';';':':':~:':-:" ';':'. . . . . ';:; :::;:;:::;:;:;=::::::;:;:::;:;:;;;::::::= .; :::::.:.;.;.;.:.:.::::;:::;:;:::;}:;:;; "", :-;:;:;:;:;;;;;:r ;::}}::=;:;::::::: ;':~:~:::;;~;~:~:::}~:~:~:~:~::{:~:~:!:}~:~:!: "';;.:::.;:;:;:::::;:;:;:;:;:;:;:;: ::::; . : ,::<:,:;:}!t:;:::;::.;. "; '; :.:,:.:,:.:::. . . , . .
Use of untreated groundwater from
production wells as potable water
Use of untreated groundwater from
production wells for showering
Residential Use of groundwater from predicted Ingestion of water
Case 1 contaminant plume as potable water
Industrial Workers
Use of groundwater from predicted
contaminant plume for showering
Crops contaminat~ from irrigating
with predicted contaminant plume
groundwater
Residential
Case 2
Use of groundwater from TSF-05
Injection Well as potable water
Use of groundwater from TSF-05
Injection Well for showering
Crops contaminated from irrigating
with TSF-oS Injection Well
groundwater
Ingestion of water
Inhalation of volatiles
Inhalation of volatiles
Consumption of crops
Ingestion of water
Inhalation of volatiles .
Consumption of crops
18
-------
Exposure scenarios evaluated in the risk assessment considered industrial and residential long-term
(chronic) exposures for the following pathways: (a) ingestion of groundwater, (b) inhalation of
volatiles while showering, and (c) ingestion of food crops (for residents only). Chronic exposures
evaluated assume contaminant exposures to workers over a 2S-year period and to re.<;idents living in
the study area over a 30-year period. Industrial and residential reasonable max4num exposure factors
were used in the risk assessment; a table of the reasonable maximum exposure factors used in the risk
assessment can be found in Table 7-8 of the RI report.
6.1.3 Risk Characterization
Risk characterization integrates the results of the exposure assessment and the toxicity assessment
in an estimate of risk to humans from the exposure to site cont~minants. Noncarcinogenic effects are
characterized by comparing projected intakes of substances to t9xicity values. The carcinogenic
effects or probability an individual will develop cancer over a lifetime of exposure are estimated from.
projected intakes and chemical-specific dose-response relationships. As discussed in the NCP,
noncarcinogenic risk is compared to a hazard quotient (HQ) of one, with an HQ of less than one
indicating it is unlikely even for sensitive subpopula\.ions to experience adverse health effects. An HQ
(the ratio of the level of exposure to an acceptable level) greater than 1.0 indicates that the exposure
level may exceed the protective level for that particular chemical. If the HQs for individual chemicals
are less than 1.0 but the sum of the HQs for all substances in an exposure medium (Le., the hazard
index) is greater than 1.0, there may be a concern for potential health effects. The acceptable risk
range for carcinogenic risk, according to the NCP, is 10-4 to 1()"6. A cancer risk level of 1 x 1
-------
Scenario
Table 6-2. Sunmiary of risk for Test Area North groundwater.
Hazard Indexb
Carcinogenic Ris~
Current industrial scenario (production wells)
Organic chemical water ingestion
Radioactive water ingestion.
InhaIation of volatiles
..."........",.........
"''''''''''..''''.......
"'''''''''''."''',,,,,, ......",,,..
,,,,,,,,,,,,,,,,,,,,...,... ..... ....
...:~.%~~:.'!::'!:i',,::..:':i.:::::=:.....
.......
"." .
:.;:.:.:.:-:.;.:.:.:.:.:.;.:.:-::.:.:.:.
,:",:.;.:-:.:.:.:.:.'.:.;.:.;.:.;-::.:.:
. . . . . . . .. ...........
... .... ......
,"""... ......
.......
',',',",',",',',',,',',',..,,-,...
.......
.....
'.""
.............
.....
.......
"',...-,....
.............
8 in 10,000,000
(8 x 10-')
6 in 10,000,000
(6 x 10-')
4 in 100,000,000
..... .:.::::::,:,:;:::,:,~:::::::~::::},gd:, :,::::',\:;'... .'.'.".... ..
"'.":.jj!:jl~jll.::r'rijtl'jlij,.'...'",...,.,..",........... ..
0.003
NN
NA
........ '"
. . . . . . . . . . .
..,...."......,.
.:::!:qi,9I:!
......
:.;.;.:.:.:.:.:.:.:.:.:.
.. .
... ..
....",.
.. ....
.... ..
3 in 1,000,000
(3 x 1~
1 in 100,000 NA
........~illi!!.1III.lli!!~ij,8I!I.i>................
Future residential exposure to groundwater plume (Case 1)
Organic chemical water ingestion
Radioactive water ingestion
InhaIation of volatiles
Organic chemical crop ingestion
Radioactive crop ingestion
..............,'..' ,.,'"''''''
.... ,.... ............,........, ..,..
"...., ..,..............,..,.., ....,
',',',',",',',',',',','.'.','.',''',',',',',',',',',',',',',,',',', ,',','."
"" ....."..,..,...."..,......,..",..".
:.iil~:~_.::.:i::'...,...:....:i.:'~.:.::::.:.....'..:'.': ....'.' ...
",.. :,:,:,;,'0:';':-:':';';'",.,., "."""""
, , , " . . . , , , , , , , , , "
.... ..
1 in 100,000
(1 x 10.5)
4 in 1,000,000
(4 x 1()"6)
7 in 10,000,000
(1 x 10"')
0.8
NA
NA
0.1
Future residential exposure to TSF-05 groundwater (Case 2)
Organic chemical water ingestion
Radioactive water ingestion
InhaIation of volatiles
Organic chemical crop ingestion
Radioactive crop ingestion
1 in 1,000
(1 x 10.3)
5 in 10,000
(5 x 1
-------
-
In summary, the risk characterization indicates there is concern for potential health risks to future
residents exposed to the contaminaTlts found in groundwater pumped from the TSF-OS Injection Well
and immediate vicinity. The primary risk driver is the ingestion of groundwater contaminated with
TCE.
6.1.4 Uncertainty
Standard EP A methodologies in risk assessment were employed to evaluate the risk to human
health from COCs in the groundwater at TAN. Risk assessment methodologies represent an inexact
science, and a number of uncertainties are associated with their application. Factors contributing to
uncertainty and limitations in the exposure assessment primarily relate to estimating contaminant
concentrations in the study area, modeling groundwater contaminant fate and transport, estimating
human exposure, and accounting for toxic effects from long-term exposure to these contaminants.
Uncertainty associated with sampling and analysis includes inherent variability in the analysis of
samples, representativeness of samples, sampling error, and heterogeneity of the sample matrix.
Sources of uncertainty in the contaminant fate and transport modeling include initial assumptions
concerning the volume and concentration of the contaminant source, dispersivity and sorption
coefficients, and aquifer physical parameters. A constant source for the contaminants based on 1992
measurements in the TSF-OS Injection Well was assumed for the fate and transport modeling. This
assumption overestimates future contaminant concentrations, which results in upper bound or worst
case risk estimates.
Estimates of exposure from contaminated media rely on assumptions that also contribute to the
Uncertainties associated with risk assessment. The current industrial exposure estimates are based on
2S-year exposure to constant concentrations of contamin:lted water, at levels currently found in the
TAN production wells. Because an air sparging system for treating the water has been installed at
TAN, workers are not exposed to COl1taminated water. The" future resident exposure estimates are
based on a 30-year exposure to cotJt!lmin!lted groundwater at constant concentrations. Because a
constant source of contamination was assumed for the injection well, exposure estimates likely
overestimate risks. The assumed exposure of future TAN residents to the existing high concentrations
of contaminantg found in the TSF-OS Injection Well (Case 2) results in an unacceptable risk according
to the ranges listed in the NCP.
There are many ':ncertainties and '.'l1knowns associated with the toxic effects of the COCs for this
risk assessment. They include extrapolation from high to low doses and from animals to humans;
species differences in uptake, metabolism, organ distribution, and target site susceptibility; and human
population variability with respect to diet, environment, activity patterns, and cultural factors.
6.2 Ecological Risk Assessment
The objective of the ecological risk assessment was to determine whether COCS found in the TAN
groundwater result in an adverse ecological impact. The ecological assessment was a qualitative!
semiquantitative appraisal of the actual potential effects of the TAN groundwater on plants and
animals (ecological receptors) other than people and domesticated animals. The scope of this study
was limited to the TAN groundwater and the TSF-OS Injection Well as the sources of contamination,
as identified in the human health assessment. Ecological risk will be reevaluated during the W AG-1
comprehensive RIlFS (OU 1-10), and a more detailed ecological risk assessment will be performed
under the WAG 10 INEL Site-wide RllFS.
-------
6.2.1 Current Exposure
On the basis of the ecological risk assessment presented in the TAN groundwater RI report,
pathways available for the exposure of ecological receptors are limited. Wells within the
contaminated zone are used for sampling purposes, and when these wells were sampled, contaminated
water was treated at the existing Interim Action treatment facility before disposal. Water from the
TAN production wells is closely monitored for contaminant~, and an air sparger system has been
installed for the drinking water supply. Therefore, there is no current exposure of ecological
receptors to the contaminated groundwater at TAN.
6.2.2 Future Exposure
Ecological receptors would be exposed primarily through irrigation of crops if TAN groundwater
is used for this purpose in the future. Contaminants would be deposited on surfaces and soil, where
they could be adsorbed onto plant surfaces, absorbed into the plant, or taken up from the soil through
the roots. Herbivores could be exposed by ingesting plant material, soil, or water; dermal contact
from contaminated plant surfaces and soil; and to a lesser degree, inhalation of resuspended
contaminated particulates. Contaminant~ can b~ absorbed into the body after being inh4.ed or
swallowed. Insectivorous animals would be similarly exposed by ingesting contaminated insects.
Widely ranging herbivores, such as pronghorn antelope, elk, and sage grouse, could transport
COl]taminant~ a considerable distance because of seasonal migrations. Carnivores could be exposed by
ingesting contaminated water or prey, dermal contact, and inhalation. Top-level carnivores are
important because they bioaccumulate contaminant~ by way of prey consumption, carrion
consumption, or fecal consumption.
A simplified exposure scenario was evaluated in the risk assessment for an herbivorous rodent.
As described above for ecological receptors, exposure would result from ingesting plant material,
soil, or water from the use of contaminated groundwater for irrigation. In general, the calculations
showed that the radiological doses in the future would be insignificant compared to background doses,
except in the case of Sr-90. There is a possibility that Sr-90 could pose adverse effects. However,
the nature of these effects cannot be fully evaluated at this level of analysis. Given the uncertainty in .
extrapolating data from laboratory studies to wild populations, it appears exposure to COCs would be
sufficiently low, and no adverse effects would be expected in rodents occupying the irrigated
cropland. Exposure to contaminant~ by higher level organisms .(predators) would also be expected to
be low. Additionally, contaminant intake by predators would likely be attenuated by ingestion of prey
from outside the contaminated zone. The results of the ecological risk assessment indicate that risk to
future ecological receptors would be low. In summary, no critical habitats are adversely affected by
the TAN groundwater contamination and no endangered species or habitats of endangered species are
adversely affected by the site contamination.
6.3 Impact of Interim Action Sampling Results on Risk A!IIUOSSIDent
The fate and transport modeling and the risk assessment were based on the RI sampling results.
As discussed in Section 5.3, contaminant concentrations are higher in wells TSF-05 and TAN-2S and
lower in TAN-26 than assumed in the fate and transport modeling (Table 5-3). New fate and
transport models were run to predict future plume concentrations using the new sampling data from
the Interim Action. However, the specific carcinogenic risk and HQs for theCOCs have not been
calculated using the new data. While the higher contaminant concentrations could indicate risks to
future receptors that are greater than previously est1m!llted in the RI, the general conclusions of the
risk assessment are still valid. Unacceptable risks would result from future residential use of
contaminated groundwater from the vicinity of the TSF-Q5 Injection Well. Therefore, the new
-------
information does not change the recommended remedial strategy for the OU 1-07B groundwater,
~hich is discussed in the following sections of this ROD.
7. DESCRIPTION OF ALTERNATIVES
Eight alternatives were assembled and screened in the TAN groundwater OU 1-07B FS. Two
alternatives were dropped from further consideration during the FS screening because these
alternatives were estimated to require more than 150 years for remediation. Two other FS
alternatives are not discussed in this ROD because they focus on containment of the hotspot, which is
also covered under the two remaining and more comprehensive alternatives. Summary descriptions of
the four remainine alternatives for reducing contamination in TAN groundwater are presented below.
In the year since the Proposed Plan was issued, new information has been developed concerning
the fate and transpon of trichloroethene in the groundwater. The estimated groundwater velocity of
the trichloroethene plume is the Same as that of the uncontaminated groundwater, which is
approximately 1 ftIday. The Interim Action conducted under the 1-07 A ROD confirmed that sludge
could be removed from tI..~ TSF-05 Injection Well but did not confirm the extent of sludge pres~nt in
the vicinity of the injection well. As a result, sludge or secondary source may be difficult or
impractical to remove. The alternative descriptions summarized below are based on those presented
in the May 1994 Proposed Plan with the following exceptions:
.
The proposal to use surfactant has been removed because of the heterogeneity of the
material disposed of in the TSF-05 Injection Well, the potential for mobilization of
cont.aminants, and the potential noncontactability of the secondary source present within
the hotspot.
Recent modeling has shown that after removal of the greater than 5,000 ",gIL TCE plmne,
approximately 200 years would be required for natural dispersion to reduce the remaining
plume to concentrations below MCLs.
.
.
The groundwater pumping rates estimated in the Proposed Plan are conservative by over
one order of magnitude, thereby excessively inflating the costs for remediation.
.
Recent groundwater monitoring data indicates that the greater than 5,000 p.gIL TCE
contaminatjon is within 200 ft of TSF-05. Therefore, there is no need to follow the
approach described in the May 1994 Proposed Plan for remediation of the hotspot and the
greater than 5,000 p.gIL TCE plume.
7.1 A1temative 1: No Action
The NCP requires a No Action alternative to establish a baseline for comparison to alternatives
that require action. Under this alternative, no attempt would be made to conWn, treat in place, or
extract and treat any contaminatPLt groundwater within OU l-07B. No institutional CODtrOls are
assumed and the Interim Action (OU 1-07 A) would not be conrimled. Groundwater mod~1i~
indicates that, with no action, the contmninslnt plume for volatile organics would contiDue to spread
and that the radiological plume would eventually shrink as a result of decay. GrouDdwarer
monitoring would be implemented under the No Action alternative to detect changes in OU l-07B that
may lead to situations that would be considered immediately daugerous to the public or enviromnent.
Any situation of this son, detected through monitoring, would require mitigative measures to be taken
to minimi7,C risk to public health and the environment;,
-------
7.2 Alternative 2: Limited Action CoDSisting of Institutional Controls
< <
Under this alternative, no action would be taken to remediate contaminated groundwater and
contaminant sources associated with QUI-07B.. Instead, the Limited Action alternative would
implement institutional controls to protect current and future users from health risks associated with
the groundwater contamination. Groundwater modeling indicates that, with no action, the
contaminant plume for VOCS would continue to spread and that the radiological plume would
eventually shrink as a result of decay. Specific actions or controls could include groundwater
monitoring, an alternative water supply, and/or access restrictions.
Groundwater monitoring would be conducted annually to monitor the distribution, migration, and
fate of contaminantc; already in TAN groundwater. Groundwater monitoring would use the existing
TAN groundwater monitoring wells for OU l-07B, and analyses of groundwater samples would target«
the COCS. An alteI'Qative water supply well could be installed in an area that does not access the
contaminated plume within the Snake River Plain Aquifer. The well would be capable of meeting the
water supply needs of future residents at TAN after the institutional control period. Access < <
restrictions would include land use notifications and fencing. Land use restrictions would include
prohibiting the placement of wells within the contaminated plume and interfering with remedial
activities. Fencing would enclose approximately 37 m2 (400 ft2) around the immediate vicinity of the
existing TSF-05 Injection Well.
7.3 Alternative 3: 5,000 micrograms per liter Tricbloroethene
Groundwater Plmne Extraction;
Hotspot Containment and/or Removal with Aboveground Treatment
This alternative would involve (a) modification and operation of the existing extraction system and
GWTF, (b) institutional controls and groundwater monitoring, (c) containment and/or removal with
aboveground treatment of the highly CODPiminated groundwater and secondary source in the
immP.iliatp. vicinity of the TSF-05 Injection Well (the feasibility of hotspot remediation will be
determined in a series of surge and stress tests), and (d) extraction and treattnent of groundwater
defined by the area of the aquifer with TCE concentrations greater than 5,000 p.glL.
This alternative would be performed in a phased approach. The existing extraction system and
treaanent facility would continue to be operated to support surge and stress of TSF-05 Injection Well
to remove as much of the secondary source as practicable in conjunction with hydraulic containment
of the hotspot. The initial phase of Alternative 3 would focus on secondary source removal through
surge and stress. The second phase would include installation of wells for implementation of hotspot
hydraulic containment. Surge and stress may continue to augment hydraulic contlllinment and will be
evaluated for effectiveness prior to implementation as a long-term remedy.
Hotspot contlllinment would involve installing one or more pumping wells to contain contaminant~
within the 5,000 p.gIL plume for ~on of groundwater. Extracted groundwater would be treated
for VOCS aboveground and reiJgected back into the aquifer within the capture zone of the extraction
welles). The process would function as a hydraulically C()IIQined system. capturing groundwater,
treating to remove the organic CQntaminatml, and then returning the groundwater back to the aquifer
within the capture zone of the extraction well(s).Effective containment of the secondary source and
capture of the reinjected groundwater may reduce conmminant migration beyond the capture zone.
Hydraulic conmi~ reduces further aquifer degradation, and ex situ VOC removal facilitates
overall improvement of aquifer water quality.
-------
. Aboveground organic compound removal would be accomplished by air stripping, followed by
carbon adsorption as necessary to remove volatilized organic compounds from vapor off-gas generated
during the stripping process. The off-gas treatment system will reduce emissions of volatilized
organic compounds to acceptable atmospheric levels in compliance with applicable or relevant and
appropriate requirements (ARARs). Radionuclide concentrations will be reduced by an ion exchange
or equivalent process to the extent practicable as determined by the agencies. After treatmeo:ot,
process effluent containing radionuclide (e.g., Sr-90, Cs-137) concentrations above MCLs may be
reinjected into the upgradient portion of the hotspot. Because there is no treatment for tritium,
process effluent containing tritium will be reinjected.
Carbon adsorption and ion exchange technologies are considered representative of available
process treatment options. Other process influent/effluent treatment options (e.g., UV-oxidation,
catalytic oxidation, etc.) were discussed in the Proposed Plan and will be considered as part of an
engineering evaluation to be conducted prior to selection of the final remedial design. Because there
is no treatment option for tritium, process effluent containing tritium will be reinjected.
The estimated costs given in .:he Proposed Plan are for a system operating at 1,000 gallons per
minute (gpm) for 3 to 6 years at a cost of $25,800,000. Given the new information described above,
the system costs based on a 3D-year operation and maintenance (O&M) operating at less than
100 gpm is estimated at $23,657,000. .
Under Alternative 3, no action other than Institutional Controls and Monitoring would be taken on
the less than 5,000 ILgIL component of the plume during implementation of the 1-07B remedial
action. Instead, the site-wide RIlFS and subsequent ROD (OU 1().{)4) would include necessary
remedial actions for that portion of the: plume outside of the hydraulic containment area. If no
remedial action were taken for the less than 5,000 ILgIL plume, contaminatP.d groundwater would
coritinue to flow downgradient at an estimated rate of approximately 1 ftlday. Groundwater fate and
transport modeling indicates aquifer dispersion would require approximately 200 years to reduce TCE
contaminant levels to MCLs and the maximum extent of the plume would be approximately 15 miles
south of TSF-OS.
7.4 Alternative 4: 2S micrograms per liter
Trichloroethene Groundwater Plmne Extraction;
Hotspot Containment and/or Removal With Aboveground Treatment
Alternative 4 involves remediation of contamin!ltPii grouDdwater with TCE COncentratiODS greater
than 25 ILgIL, as well as remediation of the secondary source at the TSF-OS Injection Well. Thus,
Alternative 4 includes remedial activity described under AltemaLve 3 with additional remediation of
the groundwater plume defined by the area of the aquifer that contains TCE concentrations over
25 ILgIL. Therefore, Alternative 4 would require additional treatment capacity over and above that
proposed for Alternative 3. The remedial action described by Alternative 4 is designed to yield the
maximum level of cleanup, and as such, corresponds to the largest volume of groundwater to be
remediated.
Model simnl!1tions were performed in an effort to systematically determine the volume of TCE-
contamin!ltPii groundwater requiring remediation. The simulation suggests that in order to achieve
target MCLs or 1()"4 to 1()'6 risk-based concentrations for contaminarm without established MCLs, the
secondary source of comaminarion around the TSF-05 Injection Well and groundwater contained in
the greater than 2S pgIL TCE plume would require remP.diation. Following remedj;ttion of the
greater than 25 ILgIL TCE plume, modeling suggests that the less than 25 p.g1L TCE plume will
-------
naturally degrade to MCLs within approximately 100 years. Revised groundwater modeling suggests
that the treatment of the greater than 25 ILglL plume can be achieved at lower pumping rates than
those assumed in the Proposed Plan.
Under Alternative 4, the hotspot would be contained and/or removed as described in Alternative 3
above and the less than 25 ILglL component of the plume would be allowed to undergo natural
attenuation to acceptable concentration levels within an institutional control period of 100 years.
Extraction and treatment of the dissolved phase groundwater plume would require a larger system
than that proposed for Alternative 3. Extraction and treatment would be accomplished via three or
more extraction wells and two or more injection wells. These welIs would be located so as to
intercept contaminated groundwater with concentrations greater than 25 ILglL, which is currently
estimated to extend 1.5 miles downgradient of the TSP-QS Injection Well.
Leaching from the secondary source would be reduced by containment and/or source removal,
and contaminants within the 25 to 5,000 ILglL TCE contaminated portion of the plume would be
drawn into the downgradient capture zone for VOC treatment to concentrations below MCLs. The
pumping rate needed to maintain the downgradient capture zone will be estimated based on
site-specific modeling conducted during remedial design and may be adjusted based on field data after
pumping begins. The cost estimate is based on the assumption that treatment of one pore volume
(resulting in a 30 year O&M period) will be sufficient to remove TCE from the dissolved phase
groundwater plume.
Aboveground treatment of the dissolved phase plume would be performed by air stripping with
vapor off-gas treatment if necessary. It is not expected that liquid effluent resulting from dissolved
phase plume remediation would require treatment to remove Sr-90, Cs-137, or U-234 due to
radioactive decay and adsorption of these contaminant.., within the hotspot.
The estimated costs given in the Proposed Plan are for a system operating at 10,000 gpm for 10
to 40 years at a cost of $94,600,000. Given the new information described above, the system costs
based on a 30-year O&M operating at less than 1,000 gpm is estimated at $29,888,000. The time
period required to operate the hotspot containment and/or removal system is estimated to be the same
as that for Alternative 3.
8. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
The EPA has established nine criteria for the evaluation of remedial activities. The remedial
alternatives were evaluated against the nine criteria, which are divided into three categories:
.
Threshold criteria (describes a level of performance)
Overall protection of human health and the environment
Compliance with ARARs
.
Balancing criteria (discusses technical advantages and disadvantages)
Long-term effectiveness and permanence
Reduction of toxicity, mobility, or volume through treatment
Short-term effectiveness
Implementability
Cost
-------
.
Modifying criteria (review and evaluation by other entities)
State acceptance
Community acceptance.
A summary of the comparative analysis of alternatives is presented in Table 8-1.
8.1 Threshold Criteria
8.1.1 Overall Protection of Human Health and the Environment
Alternative 1 is not protective of human health and the environment becauSe no action would be
taken to address groundwater contamination and no controls would be implemented to prevent use of
the groundwater. Alternative 2 would use institutional controls to protect human health and the
environment until MCLs or 10-4 to 1
-------
8.1.2 Compliance with Applicable or Relevant and Appropriate Requirements
A detailed list of ARARs pertinent to OU l-Q7B is provided in Section 10.2. The major ARAR
is the Safe Drinking Water Act. For Alternative 1, No Action, there is no ARAR analysis.
Alternative 2 would rely in part on natural processes to decrease contaminant concentrations in
groundwater and drinking water standards would be exceeded beyond 100 years. Because
Alternatives 1 and 2 do not sat;c:fy d1e two threshold criteria, they will not be discussed further.
Costs for Alternatives 1 and 2 are provided in Table 8-2.
New modeling data suggest that remediation defined by Alternative 3 would not achieve
reduction of VOCS to meet drinking water standards in the less than 5,000 p.glL TCE component of
the plume for approximately 200 years. It cannot be assumed that institutional controls would be
maintail1ed for this length of time. The reasonable timeframe for restoration of the aquifer to
drinking water standards should not exceed 100 years, which is in keeping with current land use
as~tions for INEL. At the time of the Proposed Plan, it was believed that Alternative 3 would
meet the l00-year remedial action objective (RAO). . However, recent groundwater modeling has
shown that after removal of the greater than 5,000 p.glL plume, approximately 200 years would be
requirec: for natural dispe_sion to reduce the remainir.g plume to concentrations below MCLs. Due to
the 200 years required, Alternative 3 could only be implemented if further remediation of the less
than 5,000 p.glL TCE part of the plume were included in the site-wide RIlFS. If additional remedial
action is taken to reduce the restoration timeframe to 100 years or less, Alternative 3 would be in
compliance with ARARs. Alternative 4 would treat the 25 to 5,000 p.g/L TCE contaminated
groundwater to levels such that drinking water standards would be met within 100 years. For either
Alternative 3 or 4, the hotspot would need to be removed or contained to prevent continued leaching
of the TCE contaminated secondary source. See Table 10-1 for summary of ARARs. that apply"to
Alternative 3 and Alternative 4.
8.2 Primary BalanciDg Criteria
After evaluation of each alternative under the two threshold criteria, five balancing criteria are
used to evaluate other aspects of the potential reJnMial alternatives. Alternatives 3 and 4 were
evaluated using each balancing criterion. The balancing criteria were used in refining the selection of
the remedial alternative.
8.2.1 LoDg- Term Effectiveness and Permanence
Alternative 3 would have good long-term effectiveness and permanence for the hotspot. When
combined with institutional controls, and assuming that additional remedial actions are taken to restore
the 4QUifer to below MCLs within 100 years, this alternative will be effective at preventing exposure
to 1In~rceptable levels of contamination. Alternative 4 would have the best long-term effectiveness
and permanence because it is less dependent upon institutional controls and future undetermined
remedial actions.
8.2.2 Reduc::tioD of Toxicity, Mobility, or Volume Through Treatment
Both Alternatives 3 and 4 would collect and treat COCS in the hotspot region, resulting in a
volume and mobility reduction of TCE and other contaminant~. Alternative 4 would address a much
larger volume of contaminated groundwater than Alternative 3 and would prevent migration of a
major component of the plume into previously uncontaminated groundwater.
u
-------
. Table 8-2. Estimated costs associated with remediation alternatives (present worth).
Alremative
Cost element 2 3 4
Construction 0 128,000 707,000 3,279,000
Operations" 0 0 6,507,000 7,818,000
Waste handling 0 0 1,323,000 1,323,000
Treatabilityb 0 0 2,470,000 2,470,000
Monitoring" 2,688,000 2,688,000 1,971,000 1,971,000
Indirects 403,000 403,000 6,727,000 8,034,000
Contingency 597,000 621,000 3,952,000 4,993,000
TotaJd 3,688,000 3,840,000 23,657,000 29,888,000
a. The operatiOns costs are based on a 30-year period of performance for remedial activity.
b. Treatability sbldies will be required for the connmin::lnt recovery technologies being considered for remediation of the
TSF-05 Injection WeD hotspot and the 2S to 5,000 I£glL dissolved phase plume. It is expected that the hotspot remediation
will be the same regardless of whether it comes under Alternative 3 or Alternative 4.
c. Monitoring costs for Alternatives 1 and 2 are based on a l00-year institutional CODttOI period. Monitoring costs for
A1temativcs 3 and 4 are based on a 30-year remediation period.
d. The total costs are in present worth dollars at a 5% discount rate and are expected to be within -30 to +50% of the
actual remediation costs. This is consistent with EPA guidelines for conceptual level cost esrirrulbng under CERCLA.
8.2.3 Short-Term Effectiveness
Alternatives 3 and 4 would not be expected to pose an unacceptable risk to workers or visitors
during implementation. Appropriate air pollution control equipment would be used as necessary to
ensure that air emissions do not pose an unacceptable human health risk. All potential impacts from
construction and system operations will be readily controlled using standard engineering controls and
practices. Alternative 4 is expected to achieve a greater degree of aquifer restoration in a shorter
timeframe than Alternative 3 based on capture and treatment of TCE contamin!:lted groundwater in the
greater than 25 p.g/L dissolved phase plume.
8.2.4 Implemeutability
Alternatives 3 and 4 require a phased approach to verify treatment performance and determine
sizing criteria for the remfl.dia1 design.
Alternative 4 would require a greater number of wells, additional tJ'PJItrnent capacity, and
disposal of a larger volume of residual waste, thus Alternative 4 has more technical and administrative
difficulties than Alternative 3.
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8.2.5 Cost
A ~ummary comparison of estimated costs for the four remediation alternatives is presented in
Table 8-2 and a detailed summary of estimated costs for the selected alternative are presented in
Table 8-3. These costs differ from those presented in the May 1994 Proposed Plan based on the new
information identified in Section 7. The full costs for Alternative 3 are not known because the less
than 5,000 JLglL TCE component of the plume would not be addressed until the site-wide RIlFS is
written. During implementation of the l-Q7B remedial action specified under Alternative 3, no action
other than institutional controls and monitoring would be taken on the less than 5,000 JLgfL
component of the plume. Instead, the site-wide RllFS and subsequent ROD (OU 10-(4) would
include necessary remedial actions for that ponion of the plume outside of the hydraulic containment
area.
The estimated $25,800,000 cost for Alternative 3 given in the Proposed Plan is for a treattnent
system operating at 1,000 gpm for 3 to 6 years. Given the new information described above,
secondary source containment and/or removal is expected to be achieved with a treatment system
operating at loo gpm over a 30-year O&M period with an estimated cost of $23,657,000.
Table 8-3. Cost summary for the OU l-Q7B selected alternative.
Activity
Consauction
($)
Operations
and
maintenance
($)
Waste
handling and
disposal
($)
Indirects
($)
Contingencya
($)
Subtotal
($)
Phase A
Remedial Design (RD)/
RemediaI Action Scope and
ROD revisions
NA
NA
NA
450.000
50,000
500,000
Phase B
Continuiog operation of
GWTF
Treatability studieslsuppon
activities
707.000
2.037.000
651.000
1.876,000
1,054.000
6,325,000
NA
283.000
NA
1.588,000
929.000
2,800,000
Bencb-sca1e testing
Pilot-scale testiJ! ~
NA
785.000
694,000
991.000
NA
56,000
NA
NA
NA
NA
694,000
1,832,000
Phase C
FiDa1 remediation
tec:imology
Impl-rinn and
operation
McmitoriDg
Monitoring
2,572.000
5,498,000
616.000
4.120.000
2,960,000
15.766,000
Total present value cost
4,064,000
1,971,000
11,474,000
1,323,000
8,034,000
4.9'3,000
1,971,000
29,888,000
a. Agency notification will be required prior to allocation of comiDgency. should funds in excess of 90~ of the amoums
specified for c:onstnJCtion, operations. waste hllnd1irlg. or indirects be required to complete the activity.
-------
The estimated $94,600,000 cost for Alternative 4 given in the Proposed Plan is for a treatment
system operating at 10,000 gpm for 10 to 40 years. Given the new information presented in
Section 7.4 above, secondary source containment and/or removal, and dissolved phase groundwater
treatment system operating at 1,000 gpm or less over a 30-year O&M period is estimated at
$29,888,000.
8.3 Modifying Criteria
8.3.1 State Acceptance
This assessment criterion evaluates the technical and admini!;trative issues and concerns that the
IDHW may have regarding each alternative. The IDHW has been involved with the development and
review of the proposed plan, ROD, and other project activities ,such as public meetings. The IDHW
concurs with the selected remedy as discussed in Section 9.
8.3.2 Community Acceptance
The community acceptance criterion evaluates issues and concerns the public may have
regarding each alternative described in the proposed plan and in the RIlFS. On the basis of verbal
comments received during the public meetings held on June 6, 8, and 9, 1994, and written comments
received during the comment period ending June 18, 1994, the community appears to accept the
preferred remedial alternative. Specific responses and comments on the remedial alternatives can be
found in the Responsiveness Summary appended to this document.
9. SELECTED REMEDY
9.1 Major Components of the Selected Remedy
After reviewing recent information provided by groundwater capture and treatment simulations
and subsequently evaluating Alternatives l' through 4 against the nine specific CERCLA criteria, the
selected remf'rlial action for OU 1-018 is Alternative 4: 25 micrograms per liter Trichloroethene
Groundwater Plume Extraction; Hotspot Containment and/or Removal with Aboveground Treatment.
Alternatives 1 and 2 were eliminated because they did not satisfy the threshold criteria. Alternative 3,
the preferred alternative identified in the Proposed Plan, requires a commitment to perform necessary
remf'rlial actions on the less than 5,000 p.glL plume.in a subsequent RIlFS. Also, in comparing
Alternatives 3 and 4 in light of the new information, Alternative 4 better satisfies the CERCLA
evaluation criteria (Section 8). Groundwater modeling calculations show that contaitnT1P-nt and/or
removal of the hotspot with subsequent treatment of the 25 to 5,000 p.gIL component of the plume,
would greatly reduce the extent of aquifer contaminllrion and would reduce the time for restoration of
the dissolved phase plume to drinking water standards. The operations and maintenance cost to
implement Alternative 4 would be greater than Alternative 3, but the restoration timeframe would be
accelerated.
Alternative 4 is planned to be conducted in three phases: Phase A will be completed in 1996
and serves as a transition from 1-07 A to 1-018 activities. Phase B focuses on hydraulic containment
and source removal via surge and stress from 1996 to 1998 (3-year duration). Phase B also includes
Treatability studies to evaluate innovative technologies against the selected alterDative. Bench-scale
treatability studies will be conducted during 1996 and following evaluation of bench-scale results,
pilot scale studies will be conducted during 1997 and 1998-. Evaluation of emerging technologies and
routine groundwater monitoring will be conducted concurrent with these activities. For cost
-------
-
estimating purposes, Phase C is assumed to be conducted from 1999 through 2025 (27 year duration).
Phase C implements the long-term final remedial action, is expected to be completed in no more than
100 years, and will end when the NCP review process demonstrates that RAOs have been met.
Figure 9-1 is a schematic of the estimated sequence of activities for completion of the final
remedial action. Alternative 4 is believed to provide a good balance of the evaluation criteria among
the alternatives considered. The agencies detennined that the preferred alternative will be pr('t~ive
of human health and the environment, will comply with applicable Federal and State regulations, and
will be cost effective.
9.1.1 Need for Treatability Studies
During the year following issuance of the Proposed Plan, groundwater monitoring data and
refined fate and transport simulations have suggested that initial estimates for remedial action were
overly conservative (e.g., groundwater pumping rates and size of associated treatment facilities).
Further, new technologies have advanced that show great potential for treating the organic
contamin:ltion in situ or reducing the toxicity of contamin:lnts aboveground.
Phase A
Phase B
Phase C
1-o7A Interim action 1-078 Source containment
and/or removal
I
. I
a
Radionuclide
removal testing
b
Source pump
and treat
Surge
and
stress
I
I
I
I
I
I
I
I
I
I
I
Treatability studies
eYes
Bench-scale No
Pilot scale
a) At completion 01 Phase A testing set radionuclide
discharge limits tor reinjection of process effluent
during Phase B and C.
b) Evaluate Surge and Stress 15 months after ROD
signature to determine if secondary source
removal is effective. Continue if effective,
discontinue if not effective.
c) Evaluate Treatability Study bench scale results to
select technologies for pilot scale studies.
d
Implement altemate remedy
Yes (source and/or dissolved phase)
Default pump and treat
(source and/or dissolved phase)
d) Evaluate effer.tiveness 01 source hydraufic
containment and/or removal.
e) Evaluate Treatability Study pilot scale results
against default pump and treat to select and
implement the most effective final remedial action
process. The selection may require ROD revision
and further public review and comment.
f) No technologies shown to be more effective than
default pump and treallmplement Altemative 4.
Figure 9-1. Schematic of the estimated sequence for OU 1-07B.
RED 0783
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The selected remedy of groundwater pumping, aboveground treatment (air stripping and off-gas
treatment, or equivalent technology as necessary) and reinjection of treated groundwater should be
effective in restoring much, if not all, of the aquifer to drinking water quality within 100 years. It
may also be possible to reduce the overall remedial timeframe as well as capital and/or operating
costs of the selected remedy through the use of innovative and new technologies. To provide an
opportunity to evaluate the mo~t proTTlising new and iDnovative technologies, a phased approach will
be implemented.
9.1.2 Description of Selected Remedy
Alternative 4 will be implemented in three phases:
Phase A-Transition of l-Q7 A Interim Action to l-Q7B Final Remedial Action
Phase B-HotspOt Containment and/or Removal with Treatability Studies
Phase C- Dissolved Phase Groundwater Treatn.ent with Continuation of HotspOt Containment
and/or Removal.
The overall approach for each of the three phases is summarized below:
9.1.2.1 Phase A-TraDsition of OU I-07A Interim Action to OU 1-o7B FiDal Remedial
Action. The OU l-Q7A surge and stress pumping of the TSF-QS Injection Well will continue. This
action will be done to remove secondary source material, pump and treat contamjn~tM groundwater
in the vicinity of TSP-QS, and collect data on aquifer parameters to establish the potential for
continued pumping of the hotspOt for removal of the secondary source of TCE contamin~tion. The
transition may include installation of wells to support remedial activities. Phase A is directly
associated with the OU l-Q7A ROD, which will end with the signing of the OU 1-07B ROD.
However, the OU I-07A activity will be incorporated into OU 1-07B Phase B activities, as necessary,
to meet the objectives of the OU 1-07B ROD.
Phase A will include operation of the existing GWTF to limit the migration of con~min~ntc;
from the hotspot until Phase B is initiated. Activities associated with this task include (a) performing
tests on filters, selected resins and other media (e.g., zeolites) to determine the practicability and cost-
effectiveness of radionuclide removal from extracted groundwater; and (b) surging and stressing the
TSF-OS well to remove as much secondary source as possible from the vicinity of the borehole and
increase well efficiency. .
The existing GWTF will be used to process groundwater extracted from within the greater than
S,OOO p.gfL TCE contaminated plume. Treated water will be reinjected within the extraction well
capture zone, thus creating a hydraulically contained system of extraction, treatment, and reinjection.
Hydraulic containment will enhance removal of contaminant~ in the vicinity of the well bore.
Prior to the agency decision on radionuclide performance standards, the GWTF will operate
using the existing treatment system. Following a single pass through the treatment train, the effluent
will be reinjected to the aquifer and may contain contaminantc; that exceed MCLs.
On the basis of current data, surging and stressing TSF-QS Injection Well will result in high
organic and radionuclide influent concentrations. The extraction/treatment system will ):)e operated
and/or modified to reduce effluent concentrations. of volatile organic contaminant~ below MCLs.
-------
Volatile organic compounds discharged to the atmosphere from GWTF operations will not exceed the
calculated emission rate limits specified in Table 9-1. Radionuclide concentrations will be reduced by
an ion exchange or equivalent process to the extent practicable as determined by the agencies. On the
basis of a review of the Radionuclide Removal Studies Report (phase A, activity "an) and a cost
benefit analysis of the selected treatment system, the agencies will determine radionuclide reinjection
performance standards. After treatment, Sr-90, Cs-137 and/or other radionuclides at concentrations
above MCLs may be reinjected into the upgradient portion of the hotspot.
9.1.2.2 Phase B-Hotspot CODtainment and/or Removal and Treatability Studies. Hotspot
containment anellor removal will involve implementing groundwater extraction in the hotspot area at a
rate sufficient to create hydraulic containment of TCE and other COJ1taminant.c: within the greater than
5,000 p.glL plume. Surge and stress will continue during Phase B. Surge and stress data will be
evaluated to determine whether the process is successful for removal of secondary source material.
Treatability bench- and pilot-scale studies for promising remediation technologies will run concurrent
with hotspot containment and/or removal over a 3-year period. At the end of this period, the
treatability study results will be evaluated against the long-term remedy described below as Phase C.
Phase B can be cons: lered an enhancement of the au 1-07 A Interim Action. Additional v, ells
may be installed, as necessary, and will be operated within the greater than 5,000 p.glL TCE plume at
a rate sufficient to create hydraulic containment and prevent contaminant migration. PreHminary
modeling suggests containment may be achieved with a 50 gpm pump rate; however, specific
pumping rates, well depths, number of wells and well locations will be determined in the remedial
design. Implementation of extraction, aboveground treatment, followed by reinjection will initiate
hydraulic containment within 15 months of the signing of this ROD.
Table 9-1. Idaho Administrative Procedures Act (lDAPA) emission rate screening levels, air
concentration screening levels, and calculated emission rate limits for OU 1-o7B.
IDAPA emission rate Air concentration Calculated emission
screening level screening level increments rate limit
(lblhr)a,b (p.g/m3) (lblhr)
Cont2minants
of concern
TCE
PCE
DCE
0.00051
0.013
52.7
O.077C
2.1c
0.185
5.05
1,254
39,5()()d
a. Emission screening levels for TCE, PCE, totall,2,DCE are derived from IDAPA 16.01.01.585 and
16.01.01.S86-Toxic Air Pollutants Noncarcinogenic and Carcinogenic Increments apply to operation of the
GWTF.
b. Air emission for organics will comply with the 95% removal or 3 Iblbr requirement of IDAPA
16.01.05.008 (40 CPR 264 Subpart AA).
c. Emission rate limits based on annual averages.
d. Emission rate limit based on 24 hr average.
-------
The contaminated groundwater will be treated using basically the same treatment system designed
for OU l-Q7A. The system will consist of a multimedia filter and/or separator for nonaqueous phase
liquids and suspended solids and an air stripper with air pollution controls as necessary
(e.g., activated carbon or equivalent off-gas treatment technology). The air stripper will be operated
in compliance with State and Federal air and hazardous waste management requirements. A treatment
system (e.g., ion exchange columns) will be used, as practicable, to reduce radionuclide
concentrations to performance standards established by the agencies.
On the basis of a review of the Radionuclide Removal Studies Report (phase A, activity "a") and
a cost benefit analysis of the selected treatment system, the agencies will determine radionuclide
reinjection performance standards. Should the radionuclide testing prove ineffective at reducing
radionuclide concentrations, process effluent containing radionuclides (e.g., Sr-90, Cs-137) above
MCLs will be reinjected into the aquifer within the hydraulic containment zone to enhance flushing of
contaminants within the hotspot.. Although COJ1taminant concentrations in reinjected groundwater may
exceed drinking water standards, the selected remedy employs an extraction, treatment, and
reinjection process that substantially improves aquifer water quality. Furthermore, institutional
controls will ensure that contamit .Irion will not endaLger present or future beneficial use.
Storage of hazardous or mixed waste generated from groundwater treatment constitutes
permissible storage for the purpose of accumulating sufficient quantities to facilitate treatment and
disposal. In the event that hazardous or mixed waste treatment residues are removed from storage for
treatment/disposal at the INEL, LDR compliance. may be addressed through the INEL Federal Facility
Compliance Act Site Treatment Plan and Consent Order. If hazardous or mixed waste (activated
carbon, sediments, or spent resins) generated by groundwater treatment is transported off the INEL, .
subsequent management will coinply with EPA's "Off-Site Rule" (40 CPR 300.440). All purge water
and unused and unaltered sample residue returned from analytical laboratories will be treated at a
minimum to remove VOCs and reinjected. Characterization using analytical results and/or .process
knowledgelhistory will be performed on all treatment plant waste residuals to determine compliance
with State and Federal hazardous waste management requirements. Periodic monitoring of the
treatment system influent contamin!'lted groundwater for selected organic and inorganic COCS, and
effluent air and water from the air stripper and ion exchange column will be conducted at a rate to be
determined by the agencies.
Treatability Study Evaluation-Phase B includes several two-stage treatability studies to
determine whether ~ new and innov~tive technology may be more effective than the selected remedy.
The first stage will be bench-scale evaluations. The second stage or pilot-scale testing will be
conducted if the bench-scale testing indicates the technology has potential for remeiliati~ TAN
groundwater more effectively than the selected alternative. A Treatability Study Work Plan will
describe the specific studies to be performed, schedule for implementation, and reporting format. The
Treatability Study Work Plan shall include a conceptual design and cost estimate for each of the
technologies evaluated. As. an ongoing effort, the agencies have evaluated a number of innovative
and emerging technologies. The results of this evaluation are contained in a technical report entitled,
Techniazl Memorand1Jm for Waste Area Group], Operable Unit ]'()7B, Alternatives Evaluotion
(Draft), which is contained in the administrative record. The remedies identified as having the
potential for reducing overall remediation timeframe and/or the potential for being more effective than
the selected alternative are
.
In situ bioremediation of the hotspot and the 25 to 5,000 ILg/L portion of the plume
.
Reductive iron dechlorination
-------
.
IIi situ chemical oxidation of the hotspot
.
.Natural attenuation
.
Monolithic confinement (grout curtain).
The timeframe for completion of the studies and submittal of the Treatability Study Repnrt is
36 months from the signiDg of this ROD. The pilot-scale studies will lead to a comparison of each
technology against the two threshold criteria and five balancing criteria established in the NCP to
determine whether any technology is more effective than the selected alternative.
The new and innovative technologies that will be evaluated in treatability studies, are described
below.
. In Situ Bioremediation-In situ bioremediation is an innovative technology for destroying
chlorinated contaminants dissolved in groundwater. Pilot-scale field tests of in situ bioremediation at
other sites around the country have demonstrated promising results in recent years. Through this
process, chlorinated COQtaminant!': are transformed by biological processes to lower toxicity end
products. Generally, the microorganisms responsible for the transformations do not directly feed on
the contaminant, but rather the transformations are brought about by cometabolic degradation.
Cometabolic degradation involves interactions of the contaminant!': with enzymes produced by the
microorganisms for other purposes. To achieve cometabolic degradation, other chemicals must be
present to serve as nutrient sources for the microorganisms.
The benefit of in situ bioremediation is that VOCs are treated in the aquifer, thereby lessening or
eliminariTlg the need for conventional air strippers and air pollution control devices, and their .
associated long term maintenance costs. Although extraction wells are used, the extracted water is
recycled and reinjected in separate wells as a component of the treatment systems.
Treatability testing is necessary to determine the effectiveness of active bioremediation. under site
conditions. Bench-scale testing is needed to characterize the presence of indigenous microorganisms
that can transform TCE, select nutrients and optimize nutrient concentrations, determine a range of
TCE concentrations over which bioremediation is most effective, and evaluate any intermediate
compounds that may be formed during bioremediation of TCE. If the bench-scale tests yield
promising results, pilot-scale testing will be required to determii1e and optimize nutrient delivery
systems (e.g., well configurations and pumping rates).
,
Full-scale implementation may involve development of an in situ bio-barrier transverse to the
direction of groundwater flow. The bio-barrier would be created by installing a series of injection
and extraction wells in an offset pattern across the plume. It is estimSltM that two injection wells and
three extraction wells may be needed to effectively capture the width of the plume. The optimal
location of the bio-barrier and recomm~ed pumping rates, would be determined through the
treatability study. An alternative to the bio-barrier concept may involve creating biologically active
areas within selected areas of COJItamination using extraction wells to draw contmnmSlted groundwater
through these reactive zones. The treatability study will evaluate the most effective design of an
in situ bioremfliliarion system for both the hotspot and the 2S to 5,000 p.gIL portion of the plume.
RPdnctive Iron Dechlorination--Current studies indicate that zero-valent iron is highly
effective in enhancing the rate of degradation of a wide range of chlorinated aliphatic compounds in
aqueous solution. Because zero-valent iron is readily available at low cost and bench tests have
proven its effectiveness, it is a good choice to degrade~-chlorinated aliphatic compounds such as the
-------
..
VOC COCs in the groundwater at TAN. Additionally, studies indicate that while degradation
products are created by this process, they are also destroyed given adequate retention time. Also,
laboratory tests indicate that this technology effectively reduces effluent contaminant concentrations
below analytical detection limits.
Radionuclides that are found in TAN groundwater are not expected to react with the iron fi1ings.
However, the strontium is expected to follow calcium in the water and if calcium precipitates. the
strontium will remain with the calcium carbonate. This process and its potential to produce a
secondary waste stream will be evaluated during the Treatability Study.
In Situ Chemical Oxidation-In situ chemical oxidation is an experimental technology
for degrading chlorinated solvents in groundwater. Laboratory tests and small-scale experiments have
shown that the oxidant potassium permanganate is effective in degrading TCE and PeE to less toxic
end products such as carbon dioxide. chlorine. chloride. and total manganese. This technology has
promising potential for remediating source areas. where concentrations of TCE are highest and
undissolved solvent may exist.
The potassium permanganate is injected into the aquifer and the oxidation reaction occurs in situ.
Therefore the complexity of the required aboveground treatment components is greatly reduced
compared with conventional pump and treat systems. The treatment process functions in a
hydraulically contained system. Oxidant is injected into the source area and the treated groundwater
is extracted at a downgradient well. The recovered water is tested for oxidation products and '
mnaining solvent, augmented with more oxidant if needed. and then reinjected into the source area.
A bench-scale study to evaluate this technology under site COnditiODS would ~ conducted followed by
a pilot field-scale demonstration to opt,imize remedial design.
Natural Attenuation- The effect of natural contaminant degradation processes may
augment simple aquifer dispersion during natural attfl'mtation of groundwater contamiMnm. However.
site-specific information is lacnng on the potential for biotic degradation. abiotic degradation or other
natural attenuation processes that may affect the TCE contaminatP.rl plume. A Treatability Study will
be performed to evaluate the rate and extent of natural TCE degradation. This will involve collection
and evaluation of available information on natural processes followed by a site-specific field test to
determine degradation trends based on time and distance downgradient from the secondary source. ,
The Treatability Study will evaluate degradation of TCE and all derivative products generated during
natural degradation pr~. The feS1uts of this study will be used to refine fate and transport
simulation esrimat~ of aquifer restoration timeframe and to assist in design of Phase C remedhtl
action.
Monolithic Cnnfinf'lnent- The use of grout as a physical barrier to groundwater flow is a
well established process. The determination of necessary well spacing and grout quantity will be
evaluated under the Treatability Study. If the above treatability studies do not show promise, and the
esfimatM timeframe for contimJed pumping and aboveground treatment appears indefinite. cost-
effectiveness of this option versus long-term pumping and aboveground ~t will be evaluated.
9.1.2.3 Phase C-Dissolved Phase Groundwater Tr-fnlfJIt with Confinnation of Hotspot
ConfAi1nnfJlt and/or Removal. Dissolved phase groundwater tremnlf'J't will involve the design of
extraction wells. tr-tmfI!nt systems, and reinjection wells approximately 3 years after signature of this
ROD. Phase C p!IIJMijl1 activity will be designed to capture the 2S to 5.000 p.gIL portion of the
plume. treat via air stripping, and reinject treated groundwater to enha~ natural attfl'mJation in the
less than 2S p.gIL plume. Hydraulic containment andIDr removal initiated during Phase B at the
-------
hotspot will continue throughout Phase C. The Phase C pump and treat technology may be replaced
by an innovative technology (described in Section 9.1.3) should the treatability studies indicate a
viable replacement alternative.
Phase C begins on completion of the treatability studies and involves the installation of extraction
and injection wells so spaced as to intercept the greater than 25 p.glL TCE contaminated plume.
Specific pumping rates, well depths, number of wells and welllocatioDS will be determined in the
remedial design. Aboveground treatment will be similar to that described for Phase B (air
stripping/sparging with off-gas treatment as necessary). Actual treatment system components will be
determined as a part of remedial design. However, in consideration of approximate well locations
within the dissolved phase plume, it is anticipated that the air stripping efficiency and need for air
pollution control will be minima] to achieve groundwater volatile organic contaminant treatment to
less than MCLs. There is no anticipated need for a radionuclide treatment system because
radionuclides are detected only in the vicinity of the hotspot and have not migrated downgradient.
However, based on monitoring data, agency review of the Radionuclide Removal Study Report, and
determination of radionuclide reinjection performance standards, the design may consider installation
of such equipment as a contingency. Periodic monitoring of the treatment system influent
contaminated groundwater for selected organic a:ld inorganic COCs, and of effluent air Cl.d water
emissions from the air stripper will be conducted at a rate to be determined by the agencies. Phase C
design will be initiated within six months of completion of the Treatability Study described in
Phase B.
9.1.2.4 Institutional Controls and Groundwater MonitoriDg-Institutional controls will consist
of engineering and administrative controls to protect current and future users from health risks
associated with groundwater contamination by preventing ingestion of groundwater having
contaminant concentrations of COCS exceeding MCLs or 1()"4 to 1~ risk-based concentrations for
contaminants without MCLs. Administrative controls shall include placing written notification of this
remedial action in the facility land use master r>lan; the notification shall prohibit (1) installation of
any wells accessing the aquifer within the cont~minated plume, and (2) engaging in any activities that
would interfere with the remedial activity. A copy of the notification shall be given to the Bureau of
Land Management (BLM), together with a request that a similar notification be placed in the BLM's
property management records for this site. U.S. Department of Energy shall provide EP A and the
State with written verification that notifications, including BLM notification, have been fully
implemented.
Access to this portion of the contaminant plume will be. institutionally controlled until MCLs or
1()"4 to 1~ risk-based concentrations for contaminants without MCLs are achieved. Groundwater
monitoring will be performed in accordance with monitoring plans developed as part of the Remedial
Design/Remedial Action. The plans will consider RAOs and monitoring data will be used to track the
greater than 5 p.g/L TCE plume, document COC concentration changes over time, provide
information on the attenuation rate of the plume, to evaluate atnainment of RAOs. Additional details
on institutional controls are provided in Section 7.2. Concentrations will be contoured on the basis of
the most recent data and additional samples may be collected, as necessary to establish a baseline of
contaminant concentrations prior to active remediation.
9.1.3 Selection of an Alternate Remedy to Potentially RepJace Conventional Pump and Treat
In the event t1ult one or more of the treatability studies are shown to reduce the overall remedial
timeframe or significantly reduce overall cost, the technology may be proposed as a replacement for
the base-case described as Phase C. If a technology is-. found to be more effective than continued
-------
long-term implementation of Phase C, the agencies shall, after appropriate public opportunity to
review the basis for changing the selected technology, modify this ROD as appropriate and begin
design implementation on the alternate remedy. This determination will be based on the information
provided in the Treatability Study Report, which will include a conceptual design and cost estimate
for each of the technologies evaluated as well as a comparison of each technology against the two
threshold criteria and five balancing criteria establiShed in the NCP. However, in the event that an
innovative technology is selected to replace the Alternative 4 Phase C remedy, the Phase B remedy
shall continue to operate until such time as the innovative remedial action is operational and
functional.
9.1.4 Agency Evaluation and Review of the Selected Remedy
The agencies will evaluate, at a minimum, and document the effectiveness of the selected remedy
within 5 years and every 5 years thereafter through the standard CERCLA 5-year review process.
This review does not preclude more frequent review by one or more of the agencies. Specifically,
the agencies will use, but will not be limited to the following evaluation criteria in the reviews:
.
Determine whether the portion of the groundwater plume having TCE concentrations
greater than 5,000 p.glL is effectively being contained, based on sampling results.
.
Determine whether the greater than 25 p.glL portion of the groundwater TCE plume is
attem1ariTlg as modeled if containment is effective.
.
Determine whether the groundwater restoration assumptions are still valid. These are, but
are not limited to the assumption that TCE is the major constituent defining the
contaminant plume, land use is such that institutional controls are maintained throughout
the restoration period whether or not DOE mllintain~ ownership of the property. It is
egrimlltPd that institutional controls will need to be maintained and monitored for
100 years.
.
Evaluate and use groundwater quality data and groundwater level measurements routinely
to determine treatment effectiveness and to provide indications of potential problems
regarding groundwater treatment.
On the basis of the evaluation performed during the review, a decision will be made by the
agencies to continue or discontinue the OU 1-078 remedial action. Similar evaluations will be
performed for subsequent 5-year reviews. Other factors that will be taken into consideration during
the reviews include, but are not limited to
.
Acceptability of the residual risk levels achieved
.
Cost of contim1iTlg the action in comparison to incremental risk reduction expected
.
Changes in future land use or changes in the EP A groundwater protection strategy
.
Technical practicability of restoring the aquifer (e.g., ability to contain the portion of the
plume having TCE concentrations greater than 5,000 p.g/L, modifications that could
expedite the cleanup in a cost effective manner).
-------
9.2 Remedial Action Objectives
As part of the RIlFS process, RAOs were developed in accordance with the NCP and EPA
guidance for conducting RIlFS investigations. The purpose of the objectives is to reduce the
contamination in the groundwater at TAN to ensure that offsite populations are not. at risk in the
future and that the future residents would not be at risk from use of TAN groundwater if the TAN
area were converted to the public dOm;lin at any time in the future. Remedial action objectives for
the selected alternative are
.
Phase A-Remove as much of the secondary source as possible from the vicinity of the
TSF-05 Injection Well by physically and hydraulically stressing the well. The treatment
system shall be designed such that concentrations of VOCs in the effluent are below
MCLs before reinjection into the hotspot. All attempts will be made to operate this
process as a hydraulically contained system. The air pollution control device will be
operated in compliance with ARARs. Continue surging and stressing the well for
15 months unless Phase B is ready to begin before this date.
.
Phase B-Prevent, to the maximum extent practicable, migration of contaminated
groundwater beyond the hotspot at levels above MCLs, or for those cont:lminant~ for
which an MCL does not exist, the contam!nant concentration will be such that the total
excess cancer risk posed by release of COJ1taminated groundwater will be within the
acceptable range of lQ-4 to 1~. For aboveground treatment processes using reinjection of
treated effluent, treatment shall, at a minimum, be sufficient to reduce the VOC .
concentration to below MCLs. Volatile organic compounds discharged to the atmosphere
from GWTF operations will not exceed the calculated emission rate limits specified in
Table 9-1.
.
. Phase C-Capture and treat a sufficient portion of the dissolved phase plume beyond the
hotspot to provide for aquifer cleanup within 100 years of the date of ROD signature.
For aboveground treatment processes using reinjection of treated effluent, u-rmP.flt shall
be designed to reduce the VOC concentration to below MCLs. If an MCL does not exist,
the conr:lminllnt concentration will be such that the total excess cancer risk posed by the
groundwater will be within the acceptable range of 1()"4 to 1~. Volatile organic
compounds discharged to the atmosphere from GWTF operations will not exceed the
calculated emission rate limits specified in Table 9-1.
.
Institutional controls and groundwater monitoring-Institutional controls shall be
implemented to protect current and future users from health risks associated with ingestion
of groundwater co~ining COC concentrations greater than MCLs or 10-' to 1()-6
risk-based concentrations for contaminant~ without MCLs. Institutional controls shall be
m:lintained until COC concentrations fall below MCLs or 1()"4 to 1~ risk~ased
concentrations for C01'1taminant~ without MCLs.
10. STATUTORY DETERMINATIONS
The selected remedy meets the statutory requirements of Section 121 of CERCLA, as amended by
the Superfund Amendments and Reauthorization Act, and to the extent practicable, the NCP. The
following sections discuss how the selected remedy meets these statutory requirements.
.
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10.1 Protection of Hmnan Health and the Environment
10.1.1 Protection of Hmnan Health
The selected remedy protects human health through aboveground treatment and reinjection of
treated groundwater to restore much if not all of the affected aquifer to drinking water quali+:' within
100 years. Removing contaminants will prevent further degradation of groundwater and will be
protective of future USC!. Treated water will be reinjected into the aquifer and will meet appropriate
perfonnance standards as determined during design. Any shott-term threats associated with the
selected remedy will be addressed by engineering controls and standcird health and safety practices.
10.1.2 Protection of the Environment
A qualitative/semiquantitative ecological risk assessment indicated that no exposure pathways. for
ecological receptors are present under current conditions. Potential future exposure could occur
primarily through use of contaminated water for crop irrigation.. A simplified exposure scenario was
evaluated for an herbivorous rode.1t in this future scenario. The scenario indicated that radiological
doses from exposure to TAN groundwater used for crop irrigation would be insignificant in
comparison to the radiological dose received from background sources. However, at the level of
analysis performed in the risk assessment, the nature of potential adverse effects from Sr-go cannot be
fully evaluated. Furthermore, exposure to other COCS would be sufficiently low that no adverse
effects would be expected in rodents occupying the irrigated cropland. Effects on organisms at higher
trophic levels would also be expected to be insignificant.
Nevertheless, the selected remedy provides greater protection for ecological receptors in the
future use scenario by reducing the levels of contaminant~ in water that might be used for irrigation in
that scenario. Shott-term effects on ecological receptors resulting from implementation of the selected
remedy are also not expected to be significant. The selected remedy should not result in short-term
adverse effects on the environment at TAN and will minimi7.e adverse environmental effects that
could occur as a result of futpre use of the TAN groundwater.
10.2 Compliance with ARARS
The selected remedy will comply with all Federal ARARs and promulgated State ARARs that are
more stringent than Federal ARARs. A detailed list of ARA~ for the selected altemativ~ is shown
in Table 10-1. A general description of the ARARs is SUJIJJD3rized below in Section 10.2.1.8
10.2.1 Chemica1-Spedfic ARABs
.
State of Idaho Toxic Air Pollutants, Noncarcinogenic and Carcinogenic Increments
(IDAPA 16.01.01.585 and .01.586). These requirements involve demonstration of
preconstnlction compliance with Toxic Air Pollutants emission screening levels. If the
emissions exceed the screening levels, then model results must show comp~ with the
acceptable air concentration limits for carcinogens (AACC) at the INEL bouDdary
(chronic exposure) and acceptable air concentration (AAC) limits for noncarcinogens at
the public highway for a short term exposure. If model results indicate that the AACC or
AAC will be exceeded, best available comrol technology must be applied at the source.
a. Citation of the Idaho Waste Management Regulations incoIpOrate by xefeIenc:e the federal hazardous waste
regulations.
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Table 10-1. Summary of ARARs for Alternative 4.
ARAR type
Requirements Citation Action Chemical Location
CAA and Idaho Air R.egulatiom
Idaho Air Polluamts nollCaICinogens IDAPA 16.01.01.585 "
IdahO Air Polluamts carcinogens IDAPA 16.01.01.586 "
NESHAPs - < 10 mmnlyr 40 CFR 61.92 "
NESHAPs - monitoring 40 CFR 61.93 "
ID Fugitive Dust IDAPA 16.01.01.650 and .651 "
R.CR.A aDd HWMA
Gellerator StaDdards mAPA 16.01.05.006
Hazardous Waste Determination 40 CFR 262.11 "
GeIIeral Facility Sbmdard<; mAPA 16.01.05.008
General Waste ADalysis 40 CFR 264.13 "
Location Standards 40 CFR 264.18 (a) and (b) "
Preparedness and Pmreution 40 CFR 264.31-.37 "
Closure Perfonnance Standard 40 CFR264.111 "
DisposallDeconbmimltion 40 CFR 264.114 "
UselManagemem of CODtUners 40 CFR 264 Subpart I "
Tank SyStems 40 CFR 264 Subpart I "
Misl"...I1"D~ Units 40 CFR 264 Subpart X "
Air Emission Standards for Process Vents 40 CFR 264 Subpart AA "
Land Disposal R.esIrictions IDAPA 16.01.05.011 "
RCM Section 3020 "
mc
Idaho Rules for the Consauc:tion and Use IDAPA 37.03.03 . " "
of Injec:tion Wells
m Public DriDkiDg Water
MCLs (1IIIIDerica1 sraudan:Is only) IDAPA 16.01.08.050.02 and .05 "
SecoDdaJy MCLs (DIUJIerical SIaDdanIs only) IDAPA 16.01.08.400.03 .t
NatioDal Historic I"re.k. ...tiaD Act
Assessiug iDformation Deeds 36 CFR SOO.4(a)(l)(i),(iii)(a)(2) "
Locatiug Historic Properties 36 CFR SOO.4(b) "
11ICs
RadiaIion Pro1edion of the Public aDd the EuviroIlllleDt DOE Order S4OO.5 "
Fire ProlleCtion DOE Order S480.7A "
Radioactive Waste MaDIgement DOE Order 5820.2A "
-
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.
National Emission Standards for Hazardous Air Pollutants (40 CPR 61.92) regulating
emissions of radionuclides from DOE facilities. Emissions of radionuclides other than
radon to the ambient air from DOE facilities shall not exceed those amounts that would
cause any member of the public to receive an effective dose equivalent of 10 mremlyr.
.
Safe Drinking Water Act, Underground Injection Control Program as incorporated into
Idaho Rules and Regulations for the Construction and Use of Injection Wells
(lDAPA 37.03.03), and Section 3020 of RCRA. The mc regulation establishes
standards for the quality of fluids discharged to Class V injection wells.
In addition, Section 3020 of RCRA allows reinjection of groundwater containing
hazardous constituents above regulatory limits into the aquifer from which it was
withdrawn and treated as part of a CERCLA response action if the water quality has been
substantially improved, and if the remedy will be protective of human health and the
environment upon completion of the response action. The selected remedy employs
extraction, treatment, and reinjection of process effluent, which substantially improves the
condition of the aquifer and meets t:1e substantive intent of the mc and RC:- A
regulations.
.
State of Idaho Drinking Water Standards (lDAPA 16.01.08.050.02, .05, and
16.01.08.400.03). These standards establish primary and secondary drinking water
standards, referred to in this document as MCLs. .
10.2.2 Action-Spedfic ARABs
.
National Emission Standards for Hazardous Air Pollutants emission monitoring and test
procedures (40 CPR 61.93). An IJperator of a source with radioactive (tritium) emissions
under 0.1 mremlyr is required to perform periodic confirmatory measurements to confirm
low emissions.
.
State of Idaho Rules for Control of Fugitive Dust (lDAPA 16.01.01.650 to .651) specifies
that all reasonable precautions be taken to prevent the generation of fugitive dust.
.
State of Idaho Standards for Owners and Operators of Hazardous Waste Treatment, .
Storage, and Disposal Facilities, IDAPA 16.01.05.006, Hazardous Waste Determination
(40 CPR 262.11) specifies substantive standards for the determination and. classification of
hazardous wastes.
.
State of Idaho Standards for Owners and Operators of Hazardous Waste Treatment,
Storage, and Disposal Facilities, IDAPA 16.01.05.008, General Waste Analysis
(40 CPR 264.13) contains substantive requirements for analysis of hazardous waste.
State of Idaho Standards for OWners and Operators of Hazardous Waste Treaanent,
Storage, and Disposal Facilities. IDAPA 16.01.05.008. Preparedness and Prevention
(40 CPR 264.31-.37) contains substantive standards which apply to the design. operation,
and maintenance for treatment and storage facilities involviDg hazardous wastes.
.
.
State of Idaho Standards for Owners and Operators of Hazardous Waste Treatment.
Storage, and Disposal Facilities, IDAPA 16.01.05.008, Closure Performance
(40 CPR 264.111) and Disposal or Decontamination (40 CPR 264.114) contain
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substantive requirements for post operation closure and post closure of treatment and
storage facilities involving hazardous wastes. These standards are relevant and
. appropriate for treatment process systems for extracted groundwater and sludge because it
has been determined that the CO{lr~minated plume does not contain RCRA listed waste.
These standards are applicable for the storage facility involving RCRA characteristic
waste from the treatment of the extracted groundwater and sludge.
.
State of Idaho Standards for Owners and Operators of Hazardous Waste Treatment,
Storage, and Disposal Facilities, IDAPA 16.01.05.008, Use and Management of
Containers (40 CFR 264 Subpart I) contains substantive standards regarding hazardous
waste container management and inspections for treatment and storage facilities involving
hazardous wastes.
.
State of Idaho Standards for Owners and Operators of Hazardous Waste Treatment,
Storage, and Disposal Facilities, IDAPA 16.01.05.008, Tank Systems (40 CFR 264
Subpart 1) contains substantive standards dealing with design, leak control, inspections,
and operating requirements for tank systems containing or processing hazardous waste.
.
State of Idaho Standards for Owners and Operators of Hazardous Waste Treatment,
Storage, and Disposal Facilities, IDAPA 16.01.05.008, Miscellaneous Units (40 CFR 264 .
Subpart X) contains substantive requirements for miscellaneous treatment units that may
be incorporated into future hazardous waste treatment designs based on process
technology requirements resulting from treatability studies.
.
State of Idaho Standards for Owners and Operators of Hazardous Waste Treatment,
Storage, and Disposal Facilities, IDAPA 16.01.05.008, Air Emission Standards for
Process Vents (40 CFR 264 Subpart AA). 'This regulation requires, when influent total
organic concentrations are greater than 10 ppmw, that total organic emissions from all
facility process vents be below 3 lblhr or reduction of total organic emissions by 95 % by
weight be maintained by use of a control device.
.
State of Idaho Land Disposal Restrictions, IDAPA 16.01.05.011. Hazardous waste
generated from the treatment process are subject to the substantive requirements of land
disposal restrictions (LDRs) in effect at the time of ROD signature. Land disposal
restrictions do not apply to treated groundwater reinjected into the same aquifer. Storage
of hazardous or mixed waste generated from groundwater treatlJ1ent constitutes
permissible storage for the purpose of accumulating sufficient quantities to facilitate
~tment and disposal. In the event that hazardous or mixed waste treatment residues are
removed from storage for treatment/disposal at the INEL, LDR compliance may be
addressed through the INEL Federal Facility Compliance Act Site Treatment Plan and
Consent Order.
.
Safe Drinking Water Act, Underground Injection Control Program. as incorporated into
Idaho Rules and Regulations for the Construction and Use of injectiOn Wells.
IDAPA 37.03.03 establishes substantive monitoring requirements for Class V injection
wells.
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10.2.3 Location-Specific ARARs
8
National Historic Preservation Act [36 CPR 800.4(a)(I)(i), (iii)(a)(2), and .4(b)] requires
assessing information needs and locating historic properties, and applies when lOcating
treatment systems outside the TAN facility fence.
8
State of Idaho Standards for Owners and Operators of Hazardous Waste Treatment,
Storage, and Disposal Facilities, IDAPA 16.01.05.008, General Facility Standards
[40 CPR 264.18, (a) and (b)] contain substantive design considerations for locating
hazardous waste treatment and storage facilities within a floodplain or seismic area..
10.2.4 Other Criteria, Advisories, or Guidance To-Be-Considered
.8
To-be-considered, action-specific material is contained in DOE Orders 5400.5, "Radiation
Protection of the Public and the Environment," 5480.7 A, "Fire Protection" and 5480.2A,
"Radioactive Waste Management. "
10.3 Cost Effectiveness
The selected remedy is cost effective and provides overall protection of human health and the
environment proportional to duration of the remedy.
10.4 Use of Perm~nent Solutions and Alternative Treatment or Resource
Recovery Technologies io the Maximum Extent Possible
u.S. Department of Energy, EPA, and IDHW have determined that the selected remedy
represents the maximum extent to which permanent solutions and treatment technologies can be used
in a cost-effective manner for this final remedial action. The agencies have determined that this
selected remedy. provides the best balance of trade-offs in terms of long-term effectiveness and
permanence; reduction in toxicity, mobility, or volume achieved through treatmP.nt; short-term.
effectiveness; implementability; and cost, while also considering the statutory preference for treatment
as a principal element and considering State and community acceptance. The selected remedy for
OU 1-07B is intended to help prevent further degradation of the groundwater by containi"f and
treating the source and by extracting and treating the dissolved phase plume.
10.5 Preference for Treatment as a Principal ElemeDt
By treating the cont!lmin!l~ groundwater using one or more technologies, such as air stripping,
carbon adsorption, or ion exchange, the selected remedy satisfies the statutory preference in which
treatment, as a principal element, permanently and significantly reduces the volume, toxicity, or
mobility of the hazardous substances.
11. DOCUMENTATION OF SIGNIFICANT CHANGES
In the year since the Proposed Plan was released to the public, additional groundwater sampling
results and the development of new and innovative tre!ltment technologies have allowed improvements
to be made in the evaluation of alternatives and the site groundwater model. As a result of this, the
model predicts that the dissolved portion of the TCE plume (25 to 5,000 p.gIL) can be fP.ITH"Jd'i'~ in
less time and expense than previously indicated. Specifically, Alternative 4 can now be. implemented
at a pumping rate and for a time period comparable with that presented for Alternative 3, which was
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the preferred alternative listed in the Proposed Plan. Remediation under Alternative 4 will be
completed in less than 100 years and cost approximately $30 million.
In conjunction with Alternative 4, several innovative technologies, as described in Section 9, will
be field tested to determine their applicability in treating the VOCs in the groundwater. If any of
these alternate technologies prove more effective and represent a cost savings, the most cost-effective
technology will be implemented. The selection of a substitute technology instead of the pump and
treat technology described in this ROD would only be made after appropriate public evaluation of the
benefits derived from changing the remedial action.
12. TEST AREA NORTH TRACK 1 NO ACTION SITES
The following sections of this ROD summarize information on the group of no action sites at .
TAN agencies identified by, the DOE, EP A, and IDHW as pos~g acceptable risk to human health.
The typical Superfund site is often an obvious disposal site that. contains hazardous wastes that
have leaked into underlying soils and groundwater. In these cases, the location and boundaries of
areas of cont:-iminant concentratic 15 can be readily id~ntified. Many sites at the INEL do not fit into
this typical category. Instead, they fall into the category of historical sites that have low or unknown
quantities of residual contamination. These sites are termed low probability hazardous sites. For
typical low probability hazardous sites, either the location and quantities of hazardous substances
disposed of or leaked are unknown or there is significant uncertainty in the actual conditions.
In accordance with the FFAfCO, the agencies hav,;: evaluated the potential for contamination at
the low probability hazardous sites. The evaluation process involved collecting and interpreting
existing data to determine whether the site posed an acceptable or unacceptable risk. The information
was then assembled into a decision document that consisted of a series of questions, forms, tables,
and a qualitative risk assessment. This screening approach provided for the efficient use of available
resources and for a rigorous process to evaluate the risks from these sites to determine whether.
additional investigation was required. This evaluation process was then used to determine whether
(a) the site poses a clear risk that requires an Interim Action, (b) the site should be further
investigated under CERCLA, (c) the site should be referred to another State or Federal program, or
(d) the source does not appear to pose a risk to human health or the environment and therefore
requires no action.
Over 40 sites at TAN fall into the category of low probability hazardous sites. Of these, the
30 sites discussea io. the following sections have been evaluated and are proposed for No Action under
CERCLA. The sites have been arranged into three groups: underground storage tanks, soil
coJlt2mination sites, and wastewater disposal sites. The evaluation of all of these sites bas included
record reviews, document searches, employee interviews, site visits, field screening using portable
field instruments, and/or soil sampling where appropriate. The evaluations indicate that these areas
pose an acceptable risk to human health or the environment. A brief description and summary of
each site is presented below.
12.1 Underground Storage Tanks
The following 18 former underground storage tank sites were evaluated as low probability
hazardous sites. Except where DOted, all of the tanks, their contents, and associated piping have been
removed. All of the tank sites have been backfilled with new soil and restored for unrestticted use.
In many cases, the tank and the associated piping have been recycled as scrap metal.
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Several of the tank sites had petroleum-related organic cont~mination (i.e., benzene, toluene,
ethylbenzene, and xylene) in the site soil below the excavation. In each case, a risk evaluation
determined that the residual soil concentration for these cont~minant5: did not exceed the 1()"6 (1 in
1,000,000) risk-based. concentrations for the air volatilization, soil inha1ation, soil ingestion, or
groundwater ingestion exposure routes.
OU 1-02, IET-Ol [Underground Storage Tank (TAN-318)]. IET-Ol is a former 5,OOO-gallon
gasoline tank installed in 1958 and last used in 1965. The tank contents were removed in
September 1991. The tank and the associated piping were removed in August 1992.
There were no holes in either the tank or the associated piping, and no visually stained or discolored
soil was observed in the tank excavation. Field screening during the tank removal and the results of
soil analyses from the excavation detected no organic contamination.
OU 1-02, IET-oS [Underground Storage Tank (TAN-1714)]. IET-05 is a former SSG-gallon
underground tank used for storage of fire-fighting foam (a biodegradable and nonhazardous material
only) from 1958 to 1961. The tank contents were sampled and analyzed for organic and inorganic
contaminant!:. No contaminant5: were detected at levels that eXceed the 1()"6 risk-based concentrations.
The storage tank and its associated piping were I'fmloved in 1990.
There were no holes in either the tank or the associated piping, and no visually stained or discolored
soil was observed in the tank excavation. No soil samples were collected beneath the tank: because
the tank contents were determined to be nonhazardous and no releases from the tank were found
during removal, based on visual observations and field screening.
OU 1-02, IET-09 [Underground Storage Tank (TAN-316)]. IET-09 is a former SSG-gallon lube oil
tank installed in 1958 and last used in 1960. Sample analyses of the tank contents detected .typical
petroleum constituents and elevated levels of barium. The tank contents were removed in
September 1991 and disposed of as a hazardous waste. The tank and the associated piping were
removed in October 1991.
There were no holes in either the tank or the associated piping, and no visually stained or discolored
soil was observed in the tank excavation. No releases have ever been reported and none are known
to have occurred. Field screening during the tank removal and the results of soil analyses from the
excavation detected no organic or inorganic contamination.
OU 1-02, IET-IO [Diesel Fuel Underground Storage Tank (TAN-1712)]. IET-I0 is a former
30,OOO-gallon underground tank used for storage of diesel fuel from 1957 to 1989. Removal of the
storage tank, its contents, and the associated piping were completed in 1990. Two nearby tanks, their
contents, and their associated piping were also removed in 1990. No holes were observed in the tank
or the associated piping during excavation. The analytical results from soil samples taken from the
tank excavation detected only 2.3 parts per million (ppm) of xylene.
A risk evaluation was done to determine the risk-based soil concentrations (backward calculations) of
xylene required at the site to pose an unacceptable risk. The risk evaluation est11n"te(J that xylene
concentrations in the soil would need to be 6,400 ppm to exceed an HQ of 1 for the soil ingestion, air
v01atili7.J:1tion, air inhAlAtion, or groundwater ingestion exposure routes.
OU 1-02, IET-ll (Besding on Underground Storage Tank (TAN-1713)]. IET-ll is a former
2O,OOO-gallon underground tank used for storage of diesel fuel from 1957 to 1989. Removal of the
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--
storage tank, its contents, and the associated piping were completed in 1990. Two nearby tanks, their
contents, and their associated piping were also removed in 1990.
No holes were observed in the tank or the associated piping during the excavation. The analytical
results from soil samples taken from the tank excavation detected only 0.08 ppm of toluene, 0.06 ppm
of ethylbenzene, and 2.1 ppm of xylene.
. A risk evaluation was done to determine the risk-based soil concentrations (backward calculations) of
toluene, ethylbenzene, and xylene required at the site to pose an unacceptable risk. The risk
evaluation estimated that xylene concentrations in the soil would need to be 1,310 ppm, 1,810 ppm,
and 7,320 ppm respectively to exceed an HQ of 1 for the soil ingestion, air volatilization, air
inhalation, or groundwater ingestion exposure routes.
OU 1-02, LOFI'-oS [Fuel Tanks (TAN-767 A and B)]. LOFr-05 is the site of two 35,OOO-galIon
underground tanks used for storage of heating oil from the mid 1950s to 1991. The tank contents
were removed in 1991. However, the tanks and associated piping remain in place pending future use.
All available drawings and documentation indicate that the tanks were designed and used for the
storage of fuel oil only. Personnel interviews also support that the tanks were used only to store fuel
oil for heating purposes. In addition, no releases have ever been recorded and none are known to
have occurred.
OU 1-02, LOFI'-G6 [Tank east ofTAN-631 (TAN-76S)]. LOFr-06 is a former 2,OOO-gallon
underground tank used from 1958 to 1963. The tank was designed to store waste jet fuel and
diesel-contaminated wastewater. However, all available information indicates the tank was only. used
for diesel-COl'ltamjn~ted wastewaters.
Available drawings and documentation indicate that the tank contents were removed about 1965 and
the tank was filled with sand. The site is currently covered by an asphalt road and parking lot. No
surface conamin~tion was visible in a 1966 aerial photograph before the asphalt road was built.
Geophysical surveys performed in 1990 and 1993 did not locate the tank. No releases have ever been .
recorded and none are known to have occurred during the tank's 5-year period of operation.
OU 1-02, LOFI'-08 [Underground Storage Tank (TAN-764)]. LOFI'-08 is a former 15,OOO-gallon
tank installed in 1958 and last used in 1963. Records indicate the tank was intended for storage of
potentially radioactiVf~ly contamjn~ted petroleum jet fuel, but the project was cancelled in 1961 before
the jet engines were tested. Therefore, the tanks were likely never used for their intended purpose.
In January 1990, the LOFI' -08 tank and the associated piping were removed.
No holes were observed in the tank, and field screening detected no organic contamjn~tion in the site
soil. The analytical results from soil samples collected from the tank excavation detected only 2 ppm
of toluene, 22 ppm of ethylbenzene, and 0.1 ppm of xylene.
A risk evaluation was done to determine the risk-based soil concentrations (backward calculations) of
toluene and xylene required at the site to pose an unacceptable risk. The risk evaluation estimated
that toluene, ethylbenzene, and xylene concentrations in the soil would need to be 54,000, 27,000,
and 540,000 ppm, respectively, to exceed an HQ of 1 for the soil ingestion, air voJatili7ation, air
inh~lation, or groundwater ingestion exposure routes.
OU 1-01, TSF-Gl [Underground Storage Tank (TAN-1702)]. TSF-Ol is a former 3,OOO-gallon
diesel fuel tank installed in 1953 and last used in 1985:, A pipe leak in 1983 reportedly released
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approximately 500 gallons of diesel fuel into the surrounding soil. The pipe was replaced in 1983.
The tank. its contents. and the associated piping were then removed in September 1991. No holes
were observed in the tank or the associated new piping during the excavation. Approximately 73 m3
(96 yd3) of contaminated soil were removed from the site. The analytical results from soil samples
collected from the excavation detected only 2 ppm of ethylbenzene and 9 ppm of xylene.
A risk evaluation was done to determine the risk-based soil concentrations (backward calculations) of
ethylbenzene and xylene required at the site to pose an unacceptable risk. The risk evaluation
estimated that ethylbenzene and xylene concentrations in the soil would need to be 27.000 and
540.000 ppm. respectively. to exceed an HQ of 1 for the soil ingestion. air volatilization. air
inhalation. or groundwater ingestion exposure routes.
OU 1-02, TSF-13 [Underground Storage Tank North of TAN-610 (TAN-1221)]. TSF-13 is a
fonner 55Q-gaUon gasoline tank. Records indicate the tank was installed in the early 19508 to supply' ,
a fire-pump engine. The tank and its contents were removed about 1980.
No rele<1Ses have ever beu recorded and none are knJWD to have occurred during the tank.s
operation. Geophysical surveys performed in 1993 did not locate the tank. A soil boring. completed
in 1993 at the former tank site. detected no organic vapors in the site soil. Also. no visually stained
or discolored soil was observed in the boring.
OU 1-02, TSF-14 [Underground Storage Tank (TAN-777B)). TSF-14 is a former 12.000-gaUon
tank used for the storage of heavy diesel fuel from 1954 to 1975. The tank. its contents, and the
associated piping were removed in 1991.
No holes were observed in the tank or the associated piping. Some radioactive soils were present
above the tank from another pipe and some diesel-contaminated soil was present below the fill pipe.
All soil contamination was removed. The analytical results of soil samples from the excavation
detected only 0.55 ppm of benzene. 0.77 ppm of toluene. 2.2 ppm of ethylbenzene, and 0.96 ppm of
xylene. '
A risk evaluation was done to determine the risk-based soil concentrations (backward calculations) of
benzene. toluene, ethylbenzene, and xylene required at the site to pose an Imacceptable risk. The risk
evaluation estimated' that benzene concentrations in the soil would need to exceed 197 ppm to pose a
1 x 1()"6 excess cancer risk to soil ingestion. air inhalation, air VOJati1i7~riOn, or ingestion of
groundwater exposure routes and that toluene, ethylbenzene, and xylene concentrations in the soil
would need to be 40,000.2,000. and 4.000,000 ppm. respectively, to exceed an HQ of 1 for the soil
ingestion, air volati1i~tion, air inha1ation. or groundwater ingestion exposure routes.
OU 1-02, TSF-15 [Underground Storage Tank (TAN-779)]. TSF-15 is a former 3,OOO-gaUon fuel
oil tank that contaiqed diesel fuel. Records indicate the tank was installed in 1963 and last used in
1975. The tank, its contents. and the associated piping were removed in August 1990.
No holes were observed. in the tank, and field screening detected no organic contamination in the site
soil. No visually stained or discolored soil was observed in the tank excaVation. The results from
soil sample analyses show that no organic contaminant~ were present in the site soil.
OU 1-02, TSF-24 [Underground Storage Tank (TAN-775)]. TSF-24 is a former 10.000-gallon
tank planned to store jet engine fuel between 1955 and 1960.' The tank, associated piping. and some
soil with detectable contamination were removed in September 1990.
-------
No holes were observed in the tank, and field screening detected no organic contamination in the site
soil around the tank piping. No visually stained or discolored soil was observed in the tank
excavation. The results from soil sample analyses detected no organic contamination.
OU 1-02, TSF-32 [Underground Storage Tank (TAN-601S)]. TSF-32 is a former 170-gallon tank
used to supply heating oil. Records indicate the tank was installed in the mid-1950s and last used in
the late 19508. The tank and associated piping are believed to have been removed sometime between
the late 19508 and 1967. .
The site is currently covered by an asphalt road and parking lot. Geophysical surveys performed in
1990 and 1991 did not locate the tank, which supports the assumption that the tank had been
previously removed. No releases have ever been recorded and none are known to have occurred
during the tank's brief period of operation.
OU 1-02, TSF-33 [Underground Storage Tank (TAN-602E)]. TSF-33 is a former 1O,OOO-gallon
diesel fuel tank. Records indicate the tank was installed in 1959 and last used in 1960 when the ANP
project was terminated. The tank, its contents, and the associated piping were removed in
August 1990.
No holes were observed in the tank, and field screening detected no organic cOntamination in the site
soil. No visually stained or discolored soil was observed in the tank excavation. The results from
soil sample analyses detected no organic contamination.
OU 1-02, WRRTF-09 [Underground Storage Tank (TAN-788)]. WRRTF-09 is a former
2.500-gallon diesel fuel tank used to supply an emergency generator. Records indicate the tank was
installed in 1962 and last used in 1978. The tank, its contents, and the associated piping were
removed in August 1990.
No holes were observed in the tank, and field screening detected no organic contamination in the tank
excavation. No visually stained or discolored soil was observed in the tank excavation. The results
from soil sample analyses detected no organic contamination.
OU 1-02, WRRTF-I0 [Underground Storage Tank (TAN-644)]. WRRTF-I0 is a former
550-gallon gasoline tank used to supply an emergency generator. Records indicate the tank was
installed in 1955 and last used in 1966. The tank, its contents, and the associated piping were
removed in August 1990.
No holes were observed in the tank, and field screening detected no organic contamination in the site
soil. No visually stained or discolored soil was observed in the tank excavation. The results from
soil sample analyses detected no organic contamination.
OU 1-02, WRRTF-12 [Diesel Fuel Underground Storage Tank (TAN-1706»). WRRTF-12 is a
former 1.000-galIon diesel fuel tank used to supply an emergency generator. Records indicate the
tank was installed in the late 19508 and last used in 1975. The tank, its contents, the associated
piping, and some contamin~ted soil around the tank were removed in August 1990.
No holes were observed in the tank, and field screening detected some organic contJlmination in the
site soil around the tank piping. The analytical results from soil samples taken from the tank
excavation detected 0.6 ppm of toluene, 0.8 ppm of ethylbenzene, and 7 ppm of xylene.
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A risk evaluation was done to determine the risk-based soil concentrations (backward calculations) of
toluene, ethylbenzene, and xylene required at the site to pose an unacceptable risk. The risk
evaluation estimated that toluene, ethylbenzene, and xylene concentrations in the soil would need to
be 40,000, 2,000, and 4,000,000 ppm, respectively, to exceed an HQ of 1 for the soil ingestion, air
volatilization, air inhalation, or groundwater ingestion exposure routes.
12.2 Potential Soil Contamination Sites
The following 9 low probability hazardous sites were classified as potential soil contamination
sites. Many of these sites were only suspected of having received hazardous and/or radioactive waste
during the iIDtial site identification, and the subsequent evaluation process has determined that no such
disposal activities had occurred. Other sites are known to have had some contamination present, and
the subsequent evaluation process has either documented the removal of the cont.amina.tion or
determined that contaminant concentrations remaining at the specific site(s) are at levels that pose an
acceptable risk to human health or the enviromnent.
OU 1-06, LOFT-Ol [Diesel Fue. Spills (TAN-629)]. LOFT-Ol is the site of several diesel spills that
occurred when a diesel tank overflowed during filling between 1982 and 1986. The fuel oil flowed
in!O a culvert and pooled in a ditch. The contaminated soil in the ditch was excavated and removed
in 1990.
Field screening and soil sampling detected only some petroleum-related organic contamination. . The
analytical results from soil samples detected 4.4 ppm of toluene, 2.8 ppm of ethylbenzene, and
9.3 ppm of xylene. No other hazardous or radioactive materials are known or suspected to be -
present.
A risk evaluation was done to determine the risk-based soil concentrations (backward calculations) of
toluene, ethylbenzene, and xylene required at the site to pose an unacceptable risk. The risk
evaluation estimated that toluene, ethylbenzene, and xylene concentrations in the soil would need to
be 17,000, 8,380, and 116,000 ppm, respectively, to exceed an HQ of 1 for the soil ingestion, air
volatilization, air inhalation, or groundwater ingestion exposure routes.
OU 1-01, LOFT-03 (Rubble Pit south of LOFT Disposal Pond.). LOFr-03 was used on an
irregular basis for surface disposal of construction debris such as concrete, metal, and wood from the
late 19608 to the p~rly 1970s. Mo!:t of the construction debris was removed in 1987 or 1988. The
remaining debris was removed in 1991 and disposed of at the Central Facility Area (CFA) Landfill.
Hazardous or radioactive materials are not known or suspected to have been disposed of at LOFT -03.
Field inspections of the site and field screening of the debris and soil during cleanup operations did
not reveal any organic or radiological contamination.
OU 1-06, LOFT-I0 [Sulfmic Acid Spill (fAN-771)]. LOFT-IO was a 200-gallon sulfuric acid spill
that occurred in 1983. Approximately 0.4 m3 (0.5 yd3) of contaminated soil was excavated and
disposed of at that time.
Site investigations and soil testing in 1991 showed that no acid remained in the shallow soil at this
site. No visually stained or discolored soil was observed at the site. It.is likely that the sulfuric acid
was quickly neuttalized by the naturally alkaline native site soil. Calculations show that only 0.5 m3
(0.65 yd3) of TAN soil would be required to neutralize lo-gallons of pure sulfuric acid.. Except for
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the sulfuric acid spill~ no other hazardous or radioactive ~terials are known or suspected to have
been disposed of at LOFT-IO.
OU 1-01, LOFT-ll (Cryogen Pits). LOFI'-ll is the site of three former concrete pits that were
constructed in 1963. The pits were intended for the disposal of liquid nitrogen that was to be used as
a coolant during the Liquid Cooled Reactor Experiment. The experiment was cancelled in 1967
before the pits were ever used.
. Available site engineering drawings and records document the planned use and subsequent backfilling
of the pits. Hazardous or radioactive materials are not known or suspected to have been disposed of
at LOFr -11. The site is currently covered by the concrete floor of Building T AN-629.
OU 1-01, LOFT-14 (Asbestos Pipe). LOFr-14 was an abandoned metal pipe covered with asbestos
insulation lying exposed on the ground. In July 1991, all the a,sbestos was removed from the pipe,-
packaged, and disposed of at the Asbestos Area at the Central Facilities Area Landfill. The metal
pipe and the underlying soil were also disposed of at the CFA Landfill.
Except for the asbestos insulatior_> no other hazardous or radioactive materials are known or suspected
to be present at the LOFr-14 site. Field inspections confirmed that no free asbestos fibers were
visible in the surface soils after the pipe was removed.
OU 1-01, LOFT-IS (LOFT Buried Asbestos Pit). LOFr-15 is the former site of a construction
materials bum pit used from as early as 1957 to as late as 1979. The construction debris was most
likely concrete, metal, and wood and was disposed of and burned on an irregular basis. The pit was
abandoned in 1979 and was covered with 0.6 to 1.2 m (2 to 4 ft) of soil. Most of the debris was
removed in 1992 and was disposed of at the CFA Landfill.
Hazardous or radioactive materials are not known or suspected to have been disposed of at LOFT-IS.
Field inspections of the site and field screening of the debris and soil during cleanup operations did
not reveal the presence of any organic or radiological contamination.
OU 1-01, TSF-04 (Gravel Pit/Acid Pit). TSF-04 is located in a former gravel pit used to dispose of
construction debris such as concrete, metal, and wood from the 19508 to the mid 19708. According
to personnel interviews, the only hazardous material or waste disposed of in this area was one
55-gallon dnun of sulfuric acid sometime between 1958 and 1959.
Although sampling was not conducted at TSF-04, a 1990 fiel~ inspection revealed no evidence of
stressed vegetation or surface stains at the site. In addition, sulfuric acid would have been quickly
neutralized by the naturally alkaline native soil. It has been calc-.Jated that only 0.49 m3 (0.65 yd3) of
TAN soil would be required to neutralize 10 gallons of pure suifuric acid. Any residual contaminant~
would have likely been removed by subsequent gravel quarrying activities. Except for the one drom
of sulfuric acid, no other hazardous or radioactive materials are known or suspected to have been
disposed of.at TSF-04.
OU I~2, TSF-2S [Underground Drain Sump East of TAN-609 (TAN-I737)]. TSF-2S is an
unlined drain sump used to collect waste jet fuel and other products from static engine tests. Records
indicate the sump was installed in 1955 to replace a tank that had been removed. The sump was
abandoned in 1987 and the floor drain to the sump was filled with concrete.
Available drawings and information indicate the sump was used during the ANP project only to
collect waste jet fuel from 1955 to 1961. Later use otthe building did not require the use of the
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sump. Therefore, except for jet fuel, no other hazardous or radioactive materials are known or
suspected to have been disposed of at TSF-2S. Organic vapors were detected in the soil adjacent to
the sump; however, subsequent soil samples results detected no organic contamination. There is no
planned future use for the sump.
OU 1-01, TSF-39 [Transite (Asbestos) Contamination]. TSF-39 is an area that contains small
pieces of asbestos cement (transite) and is believed to be the result of the construction activities for
LOFT. Field inspections have determined that the asbestos material is encapsulated in cement and is
not likely to be released.
Hazardous or radioactive materials are not known or suspected to have been disposed of at TSF-39.
Field inspections and field screening of the debris did not reveal the presence of any organic or
radioactive contamination.
12.3 Wastewater Disposal Sites
The following three low probability hazardous sites are classified as wastewater disposal sites
becaus.e they have been used to receive liquid waste discharges from the TAN.area facilities. The
subsequent valuation process has determined that none of the sites has received any hazardous or
radioactive wastes and that any potential contaminant..; discharged to the sites have either been
neutralized, biodegraded, or pose an acceptable risk to human health.
OU 1-09, WRRTF-02 [Two-Phase Pond (TAN-763)]. WRRTF-02 is an unlined surface water pond
that had previously received waste from only the Two-Phase Loop experiments. This pond replaced
the WRRTF-05 Injection Well that was abandoned in 1983. Waste from these experiments consisted
of primarily steam condensate and process wp.stewater potentially containing demineralization or
corrosion-inhibiting solutions. .
No hazardous or radioactive contaminant!; are known to have been discharged to the pond. Review of
engineering drawings indicates a checkvalve in the steam system would prevent any potential
contaminant!; from draining into the pond. Although no soil sampling was conducted, site inspections
revealed no evidence of contamination, stained soil, or stressed vegetation. It is believed that any
demineralization or corrosion-inhibiting solutions discharged to the pond would have been neutralized
by the naturally alkaline native soils or biodegraded.
As stated above, the WRRTF-02 pond replaced the WRRTF-OS Injection Well in 1983. Processes
that generated the wastes that were discharged to this pond are not known to have changed
significantly since the WRRTF-OS Injection Well was put into use. Therefore, although the
WRRTF-02 pond was not sampled, some qualitative infOrmation regarding potential contamination in
the pond may be gleaned from the WRRTF-OS sampling results. The results from two rounds of
groundwater monitoring samples collected in 1994 from the former WRRTF-OS Injection Well
detected only Co-6O at concentrations greater than acceptable risk levels. The presence of Co-6O in
the WRRTF-OS Injection Well.is from a one-dme release in the mid-l960s and not the result of
routine disposal activities at the WRRTF. .
OU 1-09, WRRTF-03 (Evaporation Pond). WRRTF-03 is an un1inM evaporation pond used to
dispose of process water and cooling water from 1983 to the present. This pond replaced the
WRRTF-OS Injection Well that was abandoned ii11983. Waste from these experiments consisted of
primarily steam condensate and process wastewater pofentially containil1g demineralization or
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corrosion-inhibiting solutions. Records indi~te that minor amounts of sulfuric acid, sodium
hydroxide, and hydrazine were disposed of in the pond.
No hazardous or radioactive materials are known to have been discharged to the pond. Although no
soil sampling has been conducted, records from 1985 and 1986 indicate that only low concentrations
of inorganic contaminants were discharged to the pond. In addition, site inspections revealed no
evidence of contamination, stained soil, or stressed vegetation. It is believed that any ,
demineralization or corrosion-inhibiting solutions discharged to the pond would have been neutralized
by the naturally alkaline native soils or biodegraded. .
As stated above, the WRRTF-03 pond replaced the WRRTF-05 Injection Well in 1983. Processes
that generated the w.astes that were discharged to this pond are not known to have changed
significantly since the WRRTF-05 Injection Well was put into use. Therefore, although the
WRRTF-03 pond was not sampled, some qualitative information regarding potential contamination in
the pond may be gleaned from the WRRTF-05 sampling results. The results from two rounds of
groundwater monitoring samples collected in 1994 from the former WRRTF-05 Injection Well
detected only C0-60 at concentratiQns greater than acceptable risk levels. The presence of C0-60 in
the WRRTF-05 Injection Well is from a one-time release in the mid-1960s and not the result of
routine disposal activities at the WRRTF.
OU 1-09, WRRTF-06 (Sewage Lagoon). WRRTF-06 is an unlined surface water pond that received
nonhazardous sanitary and process wastes from 1984 to the present. This pond replaced the
WRRTF-05 Injection Well that was abandoned in 1983. Waste from these experiments consisted of
primarily steam condensate and process wastewater potentially containing demineralization or
corrosion-inhibiting solutions. Records from 1982 to 1989 indicate that the sewage effluent to the
WRRTF-05 Injection Well and WRRTF-06 pond contained only low concentrations of inorganic and
organic compounds.
No hazardous materials are known to have been discharged to the pond. Although no soil sampling
was conducted, site inspections revealed no evidence of contamination, stained soil, or stressed
vegetation. It is believed that any demineralization or corrosion-inhibiting solutions discharged to the
pond would have been neutralized by the naturally alkaline Dative soils or biodegraded.
As stated above, the WRRTF-06 pond replaced the WRRTF-05 Injection Well in 1983. Processes
that generated the wastes that were discharged to this pond are not known to have changed
significantly since the WRRTF-05 Injection Well was put intC'use. Therefore, although L.-e
WRRTF-06 pond was not sampled, some qualitative information regarding potential cont~mination in
the pond may be gleaned from the WRRTF~5 sampling results. The results from two rounds of
groundwater monitoring samples collected in 1994 from the former WRRTF-05 Injection Well
detected only Co-6O at concentrations greater than acceptable risk levels. The presence of Co-6O in
the WRRTF~5 Injection Well is from a one-time release in the mid-l960s and not the result of
routine disposal activities at the WRRTF.
12.4 Decision SmmnAry for the No Action Sites
The DOE has determined that no further action is needed for the miscellaneous sites in OUs 1-01,
1-02, 1-06, and 1-09 described in Sections 12.1 through 12.3. On the basis of the Track-l
evaluations, it was determined that no significant sources of contamination exist at these sites.
Consequently, it was decided that these sites pose no unacceptable risks to receptors, and therefore no
remedial actions are necessary. .
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The EPA approves of these no action decisions, and the IDHW concurs. Both the EPA and the
IDHW have been involved in the review of the Track-1 reports, the proposed plan, this ROD, and
other project activities such as public meetings.
12.5 Documentation of Significant Cbanges
The Proposed Plan that was released for Public Comment in May 1994 identified 30 Track 1 sites
for no further action. The Track 1 process used historical and process information to evaluate the
risk posed by each site. During the public comment period, however, new site data for TSF-36
indicated .that contamination existed at the site. As a result, DOE, in conjunction with the EP A and
IDHW, decided to delete TSF-36 from the list of Track 1 no further action sites in the ROD.
Cleanup activities have been initiated at the site to reduce the threat of contaminant migration and the
risk to human health and the environment. TSF-36 will be included in the WAG 1 OU 1-10
Comprehensive RIlFS to evaluate the site conditions and make appropriate remedial
recommendaticns.
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APPENDIX A
Responsiveness Summary
A"
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.,.
Appendix A
Responsiveness Summary
OVER\'lEW
Operable Unit (OU) 1-07B is located within Waste Area Group (WAG) 1 of the Test
Area North (TAN) facility at the Idaho National Engineering Laboratory (lNEL). A5 described in
the Record of Decision (ROD), the unit comprises the Technical Support Facility (TSF) Injection
Well (TSF-OS) and the Surrounding Groundwater Contamination (TSF-23). Site evaluations of
several No Action Sites (OUs 1-01, 1-02, 1-06, and 1-09) are also included in this ROD. A
Proposed Plan was released May 1, 1994, setting forth the agencies' proposed alternative for
remediating contamination at these units. A public comment period was held from May 18,
1994, to June 18, 1994, during which the public was asked to comment on the agencies' proposed
. trea&:ment alternative for the OU 1-07B. The Proposed Plan for OU 1-07B recommended
continuing use of the extraction and treatment system built for the interim action, implementing
institutional controls and groundwater monitoring, extracting and treating all groundwater with
trichloroethene (TCE) concentrations greater than 5,000 p.g/L and implementing an enhanced
extraction technology on hotspot contaminants in the vicinity of the TSF-05 injection well. The
Proposed Plan for the remaining units recommended no action because evaluations conducted at
the units indicated either that there was no evidence of contaminant~ at the site or that the low
levels of contamination at the site did not pose an unacceptable risk to human health or the
environment.
This Responsiveness Sununary recaps and responds to significant comments received
during the public comment period for this ROD. Generally, the comments received refl~ed a
broad range of views. One person commenting on TSF-05 suggested an alternative which is now
being considered by the agencies: because the only unacceptable risk to future populations was to
potential future residents exposed to groundwater p~ directly from the TSF-05 Injection
Well, the commentor advocated rendering this scenario impossible by filling the well with
bentonite and capping the wellhead with concrete. The feasibility of a grouting option is being
examined. A detailed discussion of this and other significant comments received during the public
comment period on the Proposed Plan and the agencies' responses to them are contained below.
8a"~'ound on Connnunity Involvement
To initiate the TAN Groundwater COQtamination and No Action Site investigations,
public scoping meetings were held on February 4, 5, and 6, 1992, in Idaho Falls, Boise, and
Burley, Idaho respectively. Approximately 35 people attended the meetings. These meetings
were designed to involve the public early in the investigation; to explain the Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA) process; and to allow
representatives from the U.S. Department of Energy (DOE) and INEL to discuss the project,
answer both written and oral questions, and receive ideas and suggestions from the public. The
public comment period on the interim action was initially scheduled from January 13, 1992, to
February 12, 1992. A request for extension of the public comment period was received and
granted, extP.ndiT!g the comment period to March 13, 1992. The scoping meetings and interim
action Proposed Plan were announced. via a fact sheet conveyed through a "Dear Citizen" letter
mailed January 8, 1992, to a mailing list of 5,731 groups and individuals. On January 5, 1992,
and again on January 30, 1992, DOE, Idaho Operations Office (DOE-ID) issued a news release
announcing the Notice of Availability of the interim action Proposed Plan. The Notice of
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Availability for the Proposed Plan was published January 5, 1992, in eight major Idaho
newspapers: the Post Register in Idaho Falls, the Idaho State Jou17U2l in Pocatello, the South
Idaho Press in Burley, the Times News in Twin Falls, the Idaho Statesman in Boise, the Idaho
Press Tribune in Nampa, the Lewiston Morning Tribune in Lewiston, and the Idahonian in
Moscow. A similar newspaper advertisement was published January 30, 1992, reminding the
public of the upcoming meetings and encouraging citizens to attend and provide oral or written
comments. .
The letter, the interim action Proposed Plan, and the news release gave notice to the
public that the TSF Injection Well and Surrounding Groundwater Contamination documents would
be available before the beginning of the comment period in the Administrative Record section of
the INEL Information Repositories located in the INEL Technical Library of Idaho Falls, as well
as in city libraries in Idaho Falls, Pocatello, Twin Falls, Boise, and Moscow. The. letter and .
release notified the public of the various ways in which they could participate in the investigations
and decision-making process.
Personal telephone calls concerning the availability of TSF Injection Well and
Surrounding Groundwater Contamination documents and public meetings were made (0 key
individuals, environmental groups, and organizations by the INEL Outreach Office staff in
Pocatello, Twin Falls, and Boise. Calls were also made to community leaders in Idaho Falls and
Moscow by INEL Community Relations Program staff in Idaho Falls and Boise.
During the meetings that followed, representatives from DOE-ID and INEL discussed the
project, answered questions, and received public comments. Forms for written comments were
distributed at the meetings and the audience was encouraged to comment on the project.
Comments received during the public scoping period on the interim action Proposed Plan were
evaluated and considered as part of the Remedial Investigation (RI)/Feasibility Study (FS) process.
Regular reports concerning the status of the TSF Injection Well and Surrounding
Groundwater CoJ1tamination project were included in the INEL Reporter and mailed to individuals
who attended the meetings or who were on the INEL mailing list. Reports appeared in the
March, June, and October 1993 issues of the INEL Reporter.
When the RIlFS was complete, a Notice of Availability for the TSF Injection Well and
Surrounding Groundwater Contamination and No Action Sites Proposed Plan was published in
April 1994 in the Post Register (Idaho Falls), the Idtzho State Journal (pocatello), the South Idolw
Press (Burley), the Times News (Twin Falls), the Idolw Statesman (Boise), the Lewiston Morning
Tribune (Lewiston), the Idtzho Free Press (Nampa), and The Daily News (Moscow). A second
advertisement was placed in the same newspapers several days before each open house or meeting
to remind citizens of the opportunity to attend the meetings and provide oral or written comments.
Radio stations in Idaho Falls, Blackfoot, Pocatello, Burley, and Twin Falls ran advertisements
during the three days before the open houses at the Pine Ridge Mall in Pocatello and the INEL
office in Twin Falls.
The Proposed Plan for the ROD of the TSF Injection Well and Surrounding Groundwater
Contamination and No Action Sites was mailed May 1. 1994, to the 5.600 groups and individuals
on the mailing list. Copies of the Proposed Plan and the entire Administrative Record are
available to the public in six regional INEL information repositories: the INEL Technical Library
in Idaho Falls; INEL offices in Idaho Falls, Pocatello, Twin Falls, and Boise; the University of
Idaho Library in Moscow; and the Shoshone-Bannock Library in Fort Hall. The original
.
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documents composing the Administrative Record are located at the INEL Technical Library;
copies of the originals are located in the five other repositories.
The public comment period on the Proposed Plan for the TSF Injection Well and
Surrounding Groundwater Contamination and No Action Sites was held from May 18, 1994, to
June 18, 1994. No requests for extensions were received. Prior to the release of the Proposed
Plan, a teleconference was held among the LeagUe of Women Voters of Moscow, the
Environmental Defense Institute, DOE-ID, U.S. Environmental Protection Agency (BPA), and
Idaho Department of Health and Welfare (IDHW). The participants discussed INEL
environmental restoration issues and the TSF Injection Well and Surrounding Groundwater
Contamination and No Action Sites. The format of the teleconference allowed the Moscow
residents to ask questions and receive answers from the agency personnel about these issues.
Public meetings were held June 6,8, and 9, 1994, in Idaho Falls, Boise, and Moscow,
respectively. Approximately 35 people attended the three meetings. Representatives from -
DOE-ID, EPA Region X, and IDHW were present at the public meetings in Idaho Falls and Boise
to discuss the project, answer questions, and receive public comments. Members of DOE-ID and
IDHW were present at .he public meetings in Moscow. For one half-hour before each meeting
representatives from the agencies were available for informal discussions with the interested
public. The m~ngs were conducted in two sections: the first discussed the proposed remedial
action alternative for the TSF Injection Well and Surrounding Groundwater Contamination; the
second discussed the TAN No Action sites. These two sections of the meeting were further
divided into informal question and answer periods, followed by formal comment periods. The
entirety of each public meeting was recorded by a court reporter; ttanscripts of the meetings' have
been placed in the Administrative Record. A fact sheet was sent to the public in January 1995 to .
provide citizens with updated information on the TSF-05 Interim Action and subsequent impacts .
to the preferred alternative selected for OU 1-07B.
This Responsiveness Summary has been prepared as part of the ROD. All oral
comments, as given at the public meetings, and all written comments are repeated verbatim in the
Administrative Record for the ROD. Thirteen people submitted written C()II1111P-nts on the TSF
Injection Well and Surrounding Groundwater Contamination and No Action sites proposal and
four people gave oral comments at the public meetings. To more fully respond to each issue
raised in the comments, DOE divided the comments received into 77 separate comments. The
comments received were coded to indicate which response in the Responsiveness Summary
addresses the comment. It should be noted that in appropriate instances, the Responsiveness
Summary groups similar comments, summarizes them, and provides a single response. The ROD
presents the preferred alternative for the TSF Injection Well and Surrounding Groundwater
Contamination and No Action sites at the Radi~ve Waste Management Complex (RWMC),
selected in accordance with the CERCLA, as amended by the Superfund A.mendments and
Reauthorization Act and, to the extent practicable, the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP). The decision for this OU is based on information ~inM
in the Administrative Record.
SlInnnAI")' of Cnnnnfl!llb Received and Ageacy Respcmses
CommP.Qts and questions raised during the public COIDIDeDt period on the TAN
Groundwater aDd No Action Sites Proposed Plan are summarized below. Several questions were
answered during the informal question-and-answer period during the public IIU:!'"-riT on the
Proposed Plan. This Responsiveness Summary does ~t attempt to summarize or respond to the
issues and concerns raised during that part of the public rnP1>ri~. Complete transcripts of the
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meetings, including the agencies' responses to these informal questions are contained in the
Administrative Record. . .
Comments and questions on a variety of subjects not specific to the TAN Groundwater
and No Action Sites Proposed Plan were submitted during the public comment. period. The
agencies take public comments very seriously and have made every attempt to respond to all
comments. Some comments, how~ver, are beycnd the scope of the TAN Groundwater and No
Action Sites Proposed Plan (i.e., statements of distrust for the nuclear industry, restatements of
parts of the Propo~ed Plan, questions on contaminants not present at the site). While these
comments are summarized and grouped at the end of the Responsiveness Summary, the agencies
have not attempted to respond to these out-of-scope comments. Additional infonnation on these
topics can be obtained from the INEL Public Affairs Office in Idaho Falls; the local INEL offices
in Pocatello, Twin Falls, and Boise; and the Environmental Restoration Information Office in
Moscow. Comments and questions regarding community participation were referred to the INEL
Community Relations Coordinator and will be addressed during updates to the Community
Relations Plan. Formal comments and questions on the TAN Groundwater Contamination and No
Action Sites Proposed Plan submitted during the public comment period are answered below.
COMMENTS PERTAINING TO TSF INJECTION WELL AND SURROUNDING
GROUNDWATER CONTAMINATION (OU 1-078)
Public Participation
1. .
Comment: Two commentors' complimented the agencies on the significant
improvements in public literature being published in association with the remediation
activities at the INEL. Further, they appreciated the more open way in which
information is being provided by the agencies. (T3.;.I, T4-1)
Response: The agencies appreciate the commentors' statements. The agencies are
committed to providing open access to the decision-making process and to continuously
improving the clarity of the documents produced as part of their Federal Facilities
Agreement/Consent Order (FFAlCO).
2.
Comment: One commentor asked to be provided with additional information about the
proposed injection of treated groundwater to the aquifer. (Wll-2)
Response: The selected alternative involves reinjection of treated groundwater to the
aquifer both in the dissolved phase plume and at the hotspot. In the plume, volatile
organic compounds (V0Cs) dissolved in groundwater will be treated to less than
maximum contJlminant levels (MCLs) or 10-- to 1~ risk-based concentrations and
returned to the aquifer through a series of new injection wells. At the hotspot,
groundwater treatment will occur in a zone of hydraulic c:ontaimnt'!qf. Contamin!ltPli
groundwater will be extracted at TSF-05 or a nearby downgradient well, treated, and
reinjected at the upgradient portion of the hotspot. The extracted water will be treated, at
a minimllm, to reduce VOC concentrations to less than MCLs or to within the acceptable
risk range if MCLs do not exist. Radionuclides in the extracted water at the hotspot will
be treated to less than MCLs, or risk-based values, or to the extent practicable as
determined by the agencies. .
In addition, treatability studies will be conducted on two innovative in situ treatmertt
technologies: bioremP1fiation and chemical oxidation. If treatability testing of either of
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these technologies progresses to field scale, substances will be injected to the aquifer to
test the technology's ability to aid the remediation effort. In situ oxidation involves
adding oxidant to chemically degrade VOCs. In situ bioremediation generally involves
adding nutrients to enhmce growth of microorganisms that are responsible for degrading
VOCs. In situ bioremediation may also involve addition of microorganisms to the
aquifer to aid the degradation process. The effects of each of these substances on TAN
groundwater will first be tested and evaluated at bench':scale. If field-scale tests ciIe
implemented, effects to the aquifer will be carefully monitored.
Risk Assessment
3.
Comment: one commentor stated that there is no evidence the ecological risks from the
remediation activities were considered in the evaluation of alternatives. He contended
that, in many cases, remediation activities designed to reduce human health risks impose
unacceptable ecological risks. In this case, facility construction and the disturbance to
animal populations from operation of the facilities impose risks on local populations. He
stated that these factors should be considered in the remediation activity. (W4-1)
Response: It is true that ecological risks (as the term is used by the commentor) to
animal populations from remediation activities were not specifically addressed in the
Proposed Plan or the RI/FS. However, the types of activities proposed
(exttaction/injection well drilling, aboveground treatment, etc.) do not involve a great
deal of disturbance to the surrounding area and are not anticipated to have a significant
impact on local animal populations. The trecJtment facility will be constructed within the
TSF in an area that has bad historically high levels of activity (Le., already been .
disturbed). The agencies believe that the remediation. activity at this site will not impose
unacceptable ecological risks.
Impacts to the environment that would be unavoidable during" the impl~tion of
Alternative 4 will include disturbances to soils associated with well installation and the
layout of equipment supporting the enhanced extraction technologies and groundwater
treatment systems. The equipment layout will include the placement of a concrete pad
and enclosure (e.g., metal building) to support the different unit operations for long-term
operation. Overall, activities associated with this alternative will not pose an irreparable
threat nor a significant negative impact to site flora and fauna at TAN; no rare or
endangered plants nor suitable habitats for endan~ered animal species or spec: ~ of
special concern to the Idaho Department of Fish and Game will be impacted. In
addition, no other environmentally sensitive elements-such as archaeological or
historical sites, wetlands, or critical habitats-will be impacted.
The RI report contains an ecological risk assessment. This ecological risk assessment,
although cursory, provides a conservative estimate of the cont2min:.lnt~ of concern
introduced into the food web. This ecological risk asses.cm1f!11t is based on conservative
and general assumptions, and only one exposure route (ingestion) for one receptor
(rodent). The calCllltlited risk from organic contamin:..nk to a primary consumer is orders
of magnitude below Lowest Observable Adverse Effects Levels lending confidence that
actual risk to ecological receptors would also be insignificant.ImpJ~enti"8 Alternative 4
will not create exposure to radionuclides for ecological receptors because evaporation
ponds will not be used. The quantitative ecological risk asSe'5sment for the WAG 1
Comprehensive RIIFS will more fully address ecological receptors.
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General Comments on the Proposed Alternatives
4.
Comment: One commentor asked, "What if the remedial action objective (RAO)
changed during Phase!?" Further, he asked, "After Phase 1, what if you find that
progress towards achieving the RAO is minimal?" (W1-2, Wl-3)
Response: RAOs are goals set for protecting human health and the environment. The
way RAOs are achieved may change as a result of treatability testing (described in
Section 9) but they will remain protective of human health and the environment. If the
treatability studies result in a significant change to the remedy, the agencies will provide
information to the public. Depending on the extent of the change to the remedy, the
agencies will either issue an Explanation of Significant Difference or will issue a revised
Proposed Plan (with a new public comment period) and amend this ROD accordingly.
The comment also referred to RAOs for Phase 1 (enhanced extraction technologies), that
had been intended to help remove the secondary source of conta:nination at the hotspot.
The commentor asked what would be done if use of enhanced extraction technologies
made minimal progress toward removing the hotspot. As described in Section 9 of the
ROD, the agencies have reevaluated the Preferred Alternative described in the Proposed
Plan, and as a result, have removed the proposal to use enhanced extraction technologies
(fonnerly the focus of Phase 1). The selected remedy described in this ROD focuses on
removing as much of the secondary source as practical in Phase A (i.e., surging and
stressing well TSP-oS). If the secondary source is not removed through Phase A, any
residual will be contained and prevented from further leaching through Phase B. The
agencies will evaluate the success of the selected remedy within 5 years, and at least
every 5 years thereafter until contaminant concentrations drop below MCLs or other
risk-based levels.
5.
Comment: One commentor said that it "seems like [the agencies] might want to review
the entire approach rather than continuing pumping." (W14)
Response: The agencies agree with the commentor and have reevaluated the remedial
alternatives in light of new information that became available in the year since the
proposed plan was issued. As a result of this process, the agencies have chosen
Alternative 4. as the selected remedy rather than Alternative 3 (which was identified as
the preferred alternative in the Proposed Plan). Among the new information considered,
the agencies have found that the groundwater pUmping rates estim:ated in the Proposed
Plan are overly conservative, thereby excessively inflating the costs of reIl)Plf1ation. On
the basis of reduced pumping rates now considered adequate for Alternative 4, the total
cost of this alternative is estimated at $29,888,000. In light of this and other new
information considered, the agencies have determined that Alternative 4 satisfies the
CERCLA evaluation criteria better than Alternative 3. A complete description of the
selected remedy is presented in Section 9 of this ROD.
In addition, the agencies will evaluate the success of the selected remedy within 5 years,
and at least every 5 years thereafter until cont"min:ant concentrations drop below MCLs
or risk-based levels. Any new information generated by the relDPlf1:a1 action will be
evaluated during these periodic reviews.
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8.
9.
6.
Comment: One commentor simply stated that the groundwater should be cleaned up as
quickly as possible. (W5-1)
Response: The agencies agree with the commentor. The National Contingency Plan
which is the implementing regulation for CERCLA requires that TAN groundwater
restoration occurs within a reasonable timeframe. Furthermore, the National
Contingency Plan delineates the Groundwater Protection Strategy which will be followed
during the course of remedial action for TAN groundwater. The Groundwater Protection
Strategy requires that both current and potential future use of the groundwater be
considered in remedy selection, and that groundwater resources be protected and restored
if necessary and practicable. Therefore the agencies have determined that a reasonable
timeframe for aquifer restoration to drinking water standards should not exceed
100 years. The l00-year timeframe is consistent with current INEL land use
assumptions. The estimated time frame required . for remediation under the preferred
alternative is 30 years and is not to exceed 100 years. The preferred alternative will be
implemented in a phased approach because of the complexity of the cont:lmin:lnt~ and
aquifer system. The actual length of time necessary to remediate the hotspot and the
25-llglL groundwater plume is largely dependent upon the success of each pnase.
7.
Comment: One commentor suggested that, because the only unacceptable risk identified
in the baseline risk assessment was to a future resident who ingests drinking water taken
from the vicinity of the TSF Injection Well, it was suggested that this scenario could be
rendered impossible by filling the well with bentonite, capping the wellhead with
concrete, and covering a I-acre area around the well shaft with 2- to 4-in. size basalt
cobble 10 ft deep. He estimates the cost of this suggestion at approximately one million
dollars. (W8-2) .
Respome: The scenario envisiocled by the commentator is a more aggressive variation of
proposed Alternative 2: Limited Action Consisting of Institutional Controls. The
problem with Alternative 2 and the scenario suggested by the commentator is that it
leaves the groundwater untreated and does not prevent future resident exposure to the
large downgradient plume with higher risks than is acceptable under Federal and State
drinking water standards. To prevent this exposure it is necessary to contain and/or
remove the source of cont:lmin:lt1on. Grouting may have value in the context of another
alternative to inhibit contamin:lnt migration. The agencies agree that tre3tmP.l1t or
containment is necessary to return the aquifer to beneficial use within 100 years and
alternatives that do not provide for treatment or COnt2imnP.l1t of groundwater are
UDaCCeptable.
CoIllllleDt: One commentor stated that due to decreased repleni~l1ment (drought) and
increased use (irrigation, etc.), the water table has dropped. (W9-3)
Respome: IIi the past 5 years the average depth of the water table beneath the INEL has
dropped. In some places, the level has dropped about 10 ft, from approximately 210 to
220 ft below the surface. The water table below TAN ranges in depth from
approximately 206 to 210 ft below the surface. As the commentnr stated. this decline in
the top level of the aquifer is largely due to decreased replerUshment and increased
consumptive use.
Commeut: One commentor expressed suppon of the concept of reinjection of treated
groundwater due to the noneonsumptive use. (W11-4)
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11.
12.
Response: Comment noted and is agreed with by the agencies. The selected alternative
will employ reinjection of treated groundwater as a component of remediation.
10.
Comment: One commentor had a hard time seeing how [the agencies] can have a high
degree of confidence that [the agencies] have adequately described the extent or the
degree of contamination in the aquifer. He asserted that because the agencies are seeing
things that are S1L?riSiT1g them, this is ~ indication that they lack some understanding as
to the degree of contamination in the aquifer. The commentor also suggested that the
agencies lack an adequate understanding of how the aquifer works under the INEL.
(T4-3, T4-4)
Response: The commentor is correct in stating that there are uncertainties regarding the
magnitude and extent of cont~mination in the aquifer. The Snake River Plain Aquifer is
a complex hydrogeologic system. However, the objective of the RI process is not to
remove all uncertainty, but rather to gather information sufficient to support an informed
risk management decision regarding which remedy appears the most appropriate for the
site.
Although the groundwater contamimtion at TAN has not been fully characterized, a great
deal of data has been collected about the area. Based on the information gathered as part
of this decision making process, the agencies believe they have chosen a remedial action
that will be protective of human health and the environment.
Comment: One commentor asserted that the compounds existing in the aquifer in the
vicinity of the TSF Injection Well should be considered as listed wastes. He took issue
with DOE and EG&G's statements that inadequate records exist to determine the.past use
of the halogenated organics found in the cont~minated groundwater. The commentor
stated that it is widely known among craft workers who used TCE at TAN that the bulk
of the TCE was used for cleaning operations. He concluded by asking that a
confidential, independent survey of the current and former workers at the site be
conducted and the results of the survey be reported directly to DOE. (W13-1 through .
W13-S)
Response: DOE-ID conducted an evaluation of the solvent usage at TAN that can be
found in the Administrative Record. The document is entitled Evaluation 01 Chemical
Usage at TAN dated April 1992 and is numbered as AR 3.2 in the Administrative
Record. This evaluation concluded that the waste discharged to the aquifer through the
injection well was not a listed hazardous waste because the organic chemicals in the
waste were not used as solvents and disposal practices were not documented. This initial
evaluation was quite exhaustive and further investigation or surveys would not be a
productive use of current resources. It is likely that any identified listed waste within the
operable unit would be de-listed during the ROD and thus, the selected remedy would not
be significantly altered.
Cnmlllf!l1t: One commentor stated that the [sludge removal] cleanup operation was not
completed in accordance with the Work Package documentation and the cleanup
instructions. Specifically, the commentor states that the well was to have been flushed
until the effluent was clear, but at the termination of the work, the effluent was still laden
with contaminated sediment and sludge. (W13-6 through Wl3-8)
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13.
14.
15.
Response: The comment is correct with regard to the past events that happened during
the sludge removal activity. The full scope of the field work was not completed because
the site conditions were differeIit than planned and outside of the work scope. The
cleanup operation had two objectives. The first was to remove the sludge from within
the well. This effort was completed. The second was to continue pumping until the
water cleared up, however, this objective was not completed due to a lack of waste
effluent storage capacity. Therefore, work was suspended as documemed in the May
1992 Remedial InvestigationIFeasibility Study Work Plan for OU l-Q7B. However,
60 drumc: of sludge and liquid were removed.
Comment: One commemor stated that when the well's pump and piping were removed
after the sludge removal activity was aba~oned, external contamination (on the outside
of the pump and piping) was flushed back down the well during steam cleaning.
operations. The commemor argued that contaminated liquid, which was flushed back
down the well, should have been disposed of as mixed waste. He advocated additional
action be taken to remove the remaining sludge and COJ'ltamination from the well. .
(W13-9 through WI3-12)
Response: The commem is correct with regard to past events that occurred during the
pump and sludge removal activity. Part of the purpose of the proposed remedial action
at the TSF Injection Well (TSF-Q5) is to remove residual contaminatjon from the .
injection well. Part of the purpose of the selected alternative is to contain and treat the
portion of the aquifer COTltaminated with TCE concentrations above 5,000 p.gIL. These
actions include treannem of the contaminated groundwater with a more thorough design
than the 1990 removal effort.
Comment: One commemor favored Alternative 2 (Limited Action Consisting of
Institutional Controls). (W2-I) He argued that the movement of water in the aquifer has
been so slight that the contamination would not pose a threat to anyone unless they
drilled imo the area. "Drilling such a well," he stated, "is highly unlikely since the
property should be retained for its presem pUlpOse for a number of years imo the future. "
CN2-2, W2-3) .
Respome: For an alternative to be selected at a Superfund site, the alternative must meet
two threshold criteria: overall protection of human health and the environment and
compliance with ARARs. The primary ARAR at this site is the drinking water standards
promulgated pursuant to the Safe Drinking Water Act. Because Alternative 2 would not
have met the drinking water standards for hundreds of years in the future, it was not
selected.
Risk modeling conducted as part of the RI indicated that if the site was not feI1)ediated,
contmninant levels in the vicinity of the TSFinjection well would still exceed drinking
water standards even at this later date. In fact. the results of the RI indicated that
without remMiatio~, the well would continue to pollute the Snake River P~ Aquifer for
hundreds of years into the future.
COJIIIDfIIt: A commemor asked, "H land-use is considered, is the additional cost of
Alternative 3 justified over Alternative 2?" (WIO-I) .
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Response: The comment specifically asked whether the additional cost of Alternative 3
(i.e., the Preferred Alternative in the Proposed Plan) was justified over Alternative 2.
Please note that the agencies have reevaluated the remedial alternatives in light of new
information that became available in the year since the proposed plan was issued. A$ a
result of this process, the agencies chose Alternative 4 as the selected remedy rather than
Alternative 3. A description of the selected remedy is presented in Section 9 of this
ROD.
The need for a reasonable timeframe for restoration of TAN groundwater is dictated in
the National Contingency Plan which is the implementing regulation for CERCLA. The
remedial action for TAN groundwater is conducted in accordance with the Groundwater
Protection Strategy presented in the National Contingency Plan. This regulation requires
that both current and potential future use of the groundwater be considered in remedy
selection, and that groundwater resources be protected and restored if necessary and
practicable. Accordingly, the agencies have determined that a reasonable timeframe for
restoration of the aquifer to drinking water standards should not exceed 100 years, which
is consistent with current land use assumptions for INEL.
The agencies believe that the additional cost of Alternative 4 is justified over both
Alternatives 2 and 3. Alternative 2 proposes institutional controls to prevent the use of
contaminated groundwater until cleanup standards are achieved. However, under this
alternative, the CODtaminant plume would continue to grow and contaminant
concentrations would exceed drinking water standards for hundreds of years.
Consequently, exposure to the plume would continue to pose unacceptable risks to human
health and the environment for an unreasonably long time period. It cannot be assumed
that institutional controls would be maintained for hundreds of years. Therefore,
Alternative 2 was not selected.
16.
Alternative 3 involves removal or containment of the greater than 5;000 p.gIL portion of
the TCE plume and institutional controls for the rest of the plume. Recent modeling has
shown that after removal of the greater than 5,000 p.gIL portion of the plume,
approximately 200 years would be required for dispersion to reduce the remainiT\g plume
to concentrations below MCLs. Therefore, Alternative 3 would only meet the lID-year
restoration timeframe if further remediation of the less than 5,000 p.gIL portion of the
plume is included in the Site-wide ROD. Alternative 4 is considered more effective in
the 10T'1;-term than AltE"rnative 3 because it is less dependant on subsequent remPrlia1
actions. In addition, Alternative 4 is more effective in reducing the toxicity, mobility,
. and volume of the contaminant plume through tre:iltment because it addresses a much
larger volume of contaminants than Alternative 3, and would prevent migration of a
major component of the plume into previously uncontmnin:atP(J groundwater. With
respect to relJ)Prlia1 action costs, the operations and maintenance costs to implement
Alternative 4 would be greater than Alternative 3, but the restoration timeframe would be
accelerated. Therefore', the agencies agree that Alternative 4 better satisfies the
CERCLA evaluation criteria than does Alternative 3.
Comment: A commentor queried, "Considering the flow rate of the aquifer, has the
concentration of contaminant.~ at a point where unrestricted access will be possible
(likely) in the future been calcn1"ted to justify the cost of Alternative 31" (Wlo-2)
Response: Please note that in light of new information made available in the year since
the proposed plan was issued, the agenci~ have reevaluated the remedial alternatives.
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As a result of reevaluation of the remedial alternatives, the agencies have chosen
Alternative 4 as the selected remedy rather than Alternative 3. A description of the
selected remedy is given in Section 9 of the ROD.
Contaminant concentration levels were estimated for the time at which unrestricted access
to the site is possible. The baseline risk assessment conducted as part of the RI evaluated
risks to future residents ingesting water pumped from the TSF Injection Well. It
evaluated the risks for the years 2024, 2040, and 2094. The risk assessment assumed the
site was not remediated. Results of the risk assessment indicated that even as late as
2094 contaminant levels at the injection well will still be at levels that exceed drinking
water standards and thus pose an unacceptable risk to human health and the environment.
The agencies believe that the additional cost of Alternative 4 is justified over both
Alternatives 2 and 3. Alternative 2 proposes insti~tional controls to prevent use of
contaminated groundwater until cleanup standards are achieved by plume dispersion and
radioactive decay. However, Alternative 2 would require an uracceptable time period,
Le., hundreds of years, during which groundwater contaminant concentrations would
exceed drinking water standards. Therefore, exposure to groundwater contamination
would pose unacceptable risks to human health and the environment for an unreasonable
period of time. It cannot be safely assumed that institutional controls would be
maintained for hundreds of years, consequently Alternative 2 was not selected.
Alternative 3 involves removal or containment of the greater than 5,000 p.gIL portion of
the TCE plume and institutional controls for the remainder of the plume. Recent
modeling indicates that upon removal of the greater than 5,000 I'glL portion of the
plume; approximately 200 years would be required for dispersion to reduce the remaining
plume to concentrations below MCLs. Consequently, Alternative 3 would only meet the
lOO-year timeframe for aquifer restoration if additional remediation of the less than
5,000 p.gIL portion of the plume is included in the Site-wide ROD. Alternative 4 is
considered more effective in the long-term than Alternative 3 because it is less dependent
on subsequent remMial actions. Furthermore, Alternative 4 is more effective in reducing
toxicity, mobility, and volume of the contaminant plume through treatment because it
addresses a much larger volume of contaminants than Alternative 3, and would prevent
migration of a major component of the plume into previously uncontaminatl"tt
groundwater. Although the operations and maintenance costs are greater to implement
Alternative 4, the restoration time would be accelerated. Therefore, the agencies agree
that Alternative 4 better satisfies the CERCLA evaluation criteria than does Alternative 3.
17.
CommeDt: One commentor asked about the selected alternative, "How many injection
wells would be required and where would they be sited so as to not influence the
pump/treat operation and dilute existing groundwater contamination?" (W11-3)
.Respouse: The specific number and location of reinjection and extraction wells will be
determined as part of the RD process. The locations of the reinjection aDd extraction
wells will be selected such that the well system will provide hydraulic containment and
enh2~ groundwater extraction and cleanup as applicable. The well system will be
designed to provide fP.IT1P.di9tion of the entire TCE contaminant plume where TCE
concentrations are greater than 2S p.gIL. The remediation strategy will promote aquifer
restoration by controlled reinjection of treated groundwater into the aquifer and
simultaneous extraction and treatment of contaminated grouildwater. Dilution is not the
intent of the proposed reinjection. Reinjection will be performed upgradient of TSF-OS
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..
to maintain hydraulic control. in the zone of greatest contamination. In the dissolved
phase plume, downgradient reinjection of treated groundwater will be used to avoid
dilution of dissolved phase conPlmination.
18.
Comment: One commentor stated that he supported the selected alternative because he
couldn't see where there would be worth spending all that additional money to do
(Alternative 4) when you don't re2lly accomplish that much mote out of it. (Tl-:~)
Response: Please note that in light of new information made available in the year since
the proposed plan was issued, the agencies have re-evaluated the remedial alternatives.
& a result of re-evaluation of the remedial alternatives, the agencies have chosen
Alternative 4 as the selected remedy rather than Alternative 3.
Alternative 3 involves removal or containment of the greater than 5,000 p.glL portion of
the TCE plume and institutional controls for the remainder of the plume. Alternative 3
would only meet the tOO-year timeframe for aquifer restoration if additional remediation
of the less than 5,000 p.glL portion of the plume is included in the Site-wide ROD.
Alternative 4 is considered more effective in the long-term than Alternative 3 because it
is less dependent on subsequent remedial actions. Furthermore, Alternative 4 is more
effective in reducing toxicity, mobility, and volume of the contaminant plume through
treatment because it addresses a much larger volume of CODtaminant.c: than Alternative 3,
and would prevent migration of a major component of the plume into previously
uncontar'(!inated groundwater. Although the operations and maintenance costs are greater.
to implement Alternative 4, the restoration time would be accelerated. Furthermore, the
current cost evaluation of Alternative 4 shows that the cost of the selected alternative is
considerably less in comparison to the cost given in the Proposed Plan aDd the costs of
Alternative 3 and Alternative 4 are comparable. Therefore, the agencies agree that
. Alternative 4 better satisfies the CERCLA evaluation criteria than does Alternative 3.
19.
Comment: A person stated that one of the surprises at the site was findil'lg contaminant!i:
that the (DOE) didn't know were there. He stated that although the selected alternative
takes care of what (the agencies) currently know about the site, if there are changes in
the future, (the agencies) will have to reassess things. (T1-3)
Response: New information may be generated during the Remedial Design
(RD)/Re":1edial Action (IV.) process that could affect the remedy selected in the ROD. If
new information is received, the agencies would reassess the site in light of the new
information to determine whether changes should be made to the selected remedy. Three
types of changes could take place: (1) nonsignificant cbanges (e.g., changes that fall
within the normal scope of changes taking place during the RDIRA engineering process);
(2) significant changes (e.g., changes to a component of the remedy or a change in
timing, cost, or implementability); and (3) fundamental changes (e.g., changes that may
cause the agencies to reconsider the hazardous waste management approach selected in
the ROD) Nonsignificant changes will be recorded in the Administrative Record.
Significant changes to the ROD will be documented in an Explanation of Significant
Differences. Fundamental changes require an amendment to the ROD.
In addition, the agencies will evaluate the success of the selected remedy within 5 years,
and at least every 5 years thereafter until contaminant concentrations drop below MCLs
or risk-based levds. Any new information generated by the remedial action will be
evaluated during these periodic reviews.. .
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If the additional decisions are determined to be either (1) a significant difference to a
component of a remedy or (2) a significant change that fundamentally alters the remedy
requiring amendment of the ROD, the appropriate public information will be provided.
In the first case, and Explanation of Significant Difference (ESD) will be prepared. The
agencies would also conduct the following public involvement activities:
.
Publish a n.:;:ice ')f availability and brief description of the ESD in a local
newspaper of general circulation, as required by the CERCLA, Section 117(c).
.
Make the ESD available to the public by placing it in the admini!;trative record
file and information repository.
.
Place the information supporting the change in the aclmini!;trative record file, as
well as the lead agency's response to any comments. A Responsiveness Summary
is not required.
In the second case, the agencies would repeat the ROD process in accordance with the
Comprehensive, Environmental Response, Compensation, and Liability Act, Section 117
by issuing a revised proposed plan and an amended ROD.
20.
Comment: The Environmental Defense Institute supported Alternative 4 (25 p.glL
Groundwater Plum Extraction with Air Stripping; Enhanced Extraction of Hotspot with
Aboveground Treatment) with a few caveats. The commentor asserted that discharge of
the "treated" groundwater would contain strontium-90 at levels greater than
. 300 picocuries per liter (PCiIL). This, he main~ined, violates the Clean Water Act and
the Idaho Hazardous Waste ManagemeJit Act and, therefore, does not meet ARARs. The
commentor concluded that discharging Sr-9O at levels 300 times greater than the EPA's
MCL of 8 pCiIL so that it can migrate back into the aquifer is unconscionable. (W12-1,
WI2-2, T3-2)
Respouse: The agencies agree with the commentor regarding the preferred alternative.
The agencies have re-evaluated the remedial alternatives in the year since the Proposed
Plan was issued. As a result of this process, the agencies have chosen Alternative 4 as
the selected remedy rather than Alternative 3. A complete description of the selected
remedy is given in Section 9 of the ROD. .
The commentor is specifically concerned about discharge of treated eftluent COtmiinil\g
radionuclides at concenttations above MCLs to the TSF-07 disposal pond. Please note
that the selected remedy no longer proposes discharge of treated effluent to the TSF-07
percolation pond. Instead, the treated eft]uent will be reinjected to the aquifer through
wells designed for that purpose. The extent of radionuclide contamination in the aquifer
is limited to the hotspot in the general vicinity of the TSF-05 injection well. Therefore,
it is expected that omy the portion of the remedy which focuses on the hotspot will need
to address radionuclides.
u
.
Radionuclides will be treated at the hotspot to the extent practicable. The resins used in
the au 1-7 A Interim Action were not effective in removing cesium-137 from TAN
groundwater. Therefore, laboratory tests are currently being CODducted to determine the
best commercially-available resins to remove cesium-137, strontium-90, and other
radioDllclides from TAN groundwater. Additionally, studies are being conducted to
determine the most effective techniques (f!.g., filtering, use of clarifiers) to remove
-------
radiologically-contaminated particulate from the extracted groundwater. The agencies
will review the results of these studies in the fall of 1995 to develop treatment options for
radionuclides in the extracted groundwater. The agencies will then evaluate the various
treatment options within the context of the CERCLA threshold and balancing criteria to
assess their anticipated relative performance for this final remedy. The CERCLA
evaluation criteria are discussed in Section 8 of this ROD. If none of the active treatment
options effectively satisfy the evaluation criteria, a possible option could include no active
radionuclide removal from the extracted groundwater. Under this "worst case" option,
the extracted groundwater would be treated to remove VOCs only, and then reinjected
into the upgradient portion of the hotspot. In this way, the radiologically cont.aminated
groundwater would be hydraulically contained with extraction downgradient and
reinjection upgradient. The extent of radionuclide cont.amination would decrease over
time due to radioactive decay.
The extent to which radionuclides will be treated at the hotspot cannot be determined
until the results of the laboratory studies are available.. The agencies will reach a
decision regarding radionuclide treatment by the fall of 1995 after they fully evaluate the
laboratory tes..s. However, since there is currently no practical treatment technology for
tritium, it is expected that the effluent reinjected into the hotspot will contain tritium.
Provisional startup of the Groundwater Test Facility will occur prior to the agencies
decision regarding radionuclide treatment, concurrent with the resin tests. Water would
be pumped from TAN-25 or one of the other wells located farther from TSF-Q5. These
wells are not expected to have as high of a percentage of contaminated. sludges or
concentration of dissolved contaminants as TSF-05. By pumping from these wells during
provisional startup, the elements of the treatment train can be optimized, and data
regarding removal efficiencies for COCS will be obtained, while still providing some
mass removal for the VOCs. These data will be useful in manT'lg the decision on
radionuclide removal standards. Treated effluent will be reinjected to upgradient portions
of the hotspot.
21.
The selected remedy meets ARARs by restoring as much of the aquifer as practicable in
accordance with the Groundwater Protection Strategy presented in the National
Contingency Plan. This regulation requires that both current and potential future use of
the groundWater be considered in remedy selection, and that groundWater resources be
protected and restored if necessary and practicable. Accordingly, the agencies have
determined that a reasonable time frame for restoration of the aquifer to drinking water
standards should not exceed 100 years, which is consistent with current land use
assumptions for the INEL.
Comment: The Environmental Defense Institute (ED!) supports Alternative 4: 25 ",gIL
Groundwater Plume Extraction with Air Stripping; Enhanced Extraction of Hotspot with
Aboveground Treatment but suggests use of a lined evaporation pond to receive. the
treated discharge from the filtration system at TAN. (W12-3)
Respome: The agencies agree with the commentor regarding the preferred alternative.
The agencies have re-evaluated the remedial alternatives in the year since the Proposed
Plan was issued. As a result of this process, the agencies have chosen Alternative 4 as
the selected remedy rather than Alternative 3. A complete description of the selected
remedy is given in Section 9 of the ROD.
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The commentor specifically suggests discharge of treated effluent to a lined evaporation
pond instead of a percolation pond. The agencies propose that the treated effluent will be
reinjected to the aquifer through wells designed for that purpose and therefore unlined
percolation ponds will not be used to receive effluent.
The extent of radionuclide contamination in the aquifer is limited to the hotspot in the
general vicinity of the TSF-05 injection well. So it is expected that only the portion of
the remedy which focuses on the hotspot will need to address radionuclides.
Radionuclides will be treated at the hotspot to the extent practicable. The resins used in
the au 1-7A Interim Action were not effective in removing cesiwn-137 from TAN
groundwater. Therefore, laboratory tests are currently being conducted to determine the
best commercially-available resins to remove cesium-137, strontium-90, and other
radionuclides from TAN groundwater. Additionally, studies are being conducted to
determine the most effective techniques (e.g., filtering, use of clarifiers) to remove
radiologically-contaminated particulate from the extracted groundwater. The agencies
will review the results of these studies in the fall of 1995, to develop treatment options
for radionuclides in we extracted groundwater. The agencies will then evaluate the
various treatment options within the context of the CERCLA threshold and balancing
criteria to assess their anticipated relative performance for this final remedy. The
CERCLA evaluation criteria are discussed in Section 8 of this ROD. If none of the
active treatment options effectively satisfy the evaluation criteria, a possible option could
include no active radionuclide removal from the extracted groundwater, Under this
"worst case" option, the extracted groundwater would be treated to remove VOCS only,
and then reinjected into the upgradient portion of the hotspot. In this way, the
radiologically cot'ltaminated groundwater would be hydraulically contained with extraction
downgradient and reinjection upgradient. The extent of radionuclide con~mination
would decrease over time due to radioactive decay.
The extent to which radionuclides will be treated at the hotspot cannot be determined
until the results of the laboratory studies are available. The agencies will reach a
decision regarding radionuclide treatment by the fall of 1995, after they fully evaluate the
laboratory tests. However, since there is currently no practical treatment techi1ology for
tritium, it is expected that the effluent reinjected into the hotspot will contain tritium.
22.
Comr-~: A number "f commentors supported proposed Alternative 3 (5,000 p.glL) .
Groundwater Plume Extraction; Enhanced Extraction of Hotspot with Aboveground
Treatment. (WI-I, W3-1, Wll-l, Tl-1, TI-4, T2-1)
Respoose: Please note that in light of new information made available in the year since
the proposed plan was issued, the agencies have reevaluated the remedial alternatives.
As a result of reevaluation of the remedial alternatives, the agencies have chosen
Alternative 4 as the selected remedy rather than Alternative 3.
-
DOE, EPA, and IDHW agree that Alternative 4 is the alternative that best meets the
RAO and the nine evaluation criteria identified under the CERCLA. A long-term
groundwater monitoring program will ensure that this selected remedy will be protective
of human health and the environment.
Alternative 3 would only meet the l00-year timeframe for aquifer restoration if additional
remediation of the less than 5,000 p.glL portion of the plume is included in the Site-wide
-------
ROD. Alternative 4 is considered more effective in the long-term than Alternative 3
because it is less dependent on future remedial actions. Furthermore, Alternative 4 is
more effective in r~ucing toxicity, mobility, and volume of the contaminant plume
through treatment because it addresses a much larger volume of contaminantg than
Alternative 3, and would prevent migration of a major component of the plume into
previously uncontaminated groundwater. Also the current cost evaluation of Alt~rnative
4 shows that the cost of th~ selected alternative is considerably less in compari&':':l to the
cost given in the Proposed Plan and the costs of Alternative 3 and Alternative 4 are
comparable.
23.
Comment: While a number of commentors expressed their preferences for other
proposed alternatives, one commentor expressed strong disagreement with the selected
alternative. The commentor argued that the cost to taxpayers does not justify remediating
a negligible public health risk. (W8-1) ,
Response: Please note that, in light of new information made available in the year since
the proposed plan was issued, the agencies have reevaluated the remedial alternatives.
A$ a result of reevalt.ation of the remedial alternatives, the agencies have chosen
Alternative 4 as the selected remedy rather than Alternative 3. A description of the
selected remedy is given in Section 9 of the ROD.
The agencies share the commentor's concerns regarding the amount of money spent on
remedial actions. The cost estimate of approximately $29,888,000 million for the
preferred alternative includes capital costs associated with construction, operations and
maintenance costs, and post-closure costs for long-term monitoring. The current
evaluation of Alternative 4 shows that the cost is considerably less in comparison to the
cost given in the Proposed Plan and the costs of Alternative 3 and Alternative 4 are
comparable.
Despite the high cost of remediating this site, the CERCLA requires that actual or
threatened releases of hazardous substances that may present an imminent and substantial
endangerment to human health and welfare or the environment be addressed by
implementing a remedial action. The National Contingency Plan which is the
implementing regulation for CERCLA requires that TAN groundwater restoration occurs
within a reasonable timeframe. Furthermore, the National Contingency Plan delineates
the Groundwater Protection Strategy, which will ,be followed during the cou"~e of
remedial action for TAN groundwater. The GroUndwater Protection Strategy requires
that both current and potential future use of the groundwater be considered in remedy
selection, and that groundwater resources be protected and restored if necessary and
practicable. Therefore, the agencies have detertnined that a reasonable timeframe for
aquifer restoration to drinking water standards should not exceed 100 years. The
lOO-year timeframe is consistent with current INEL land use assumptions.
Alternative 4 is considered more effective than Alternative 3 in the long-term because it
is less dependent on future remedial actions. Furthermore, Alternative 4 is more'
effective in reducing toxicity, mobility, and volume of the contaminant plume through
treatment because it addresses a the largest volume of contaminant~, and would prevent
migration of a major component of the plume into previously uncontaminated
groundwater. Although the operations and maintenance costs are greater to implement
Alternative 4 as opposed to Alternative 3, the restoration time would be accelerated.
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..
24.
25.
."
. ~
Therefore, the agencies agree that Alternative 4 best satisfies the CERCLA evaluation
criteria.
Remedial DesignlRemedial Action Concerns
Comment: One commentor stated that, "In 1953, the TSF Injection Well was drilled at
TAN. It was used from 1955 thrcugh 1972. The well was drilled to a depth of:lO ft.
Perforations to allow deposit of injected materials into the aquifer were placed from 180
to 244 ft and from 269 to 305 ft. Presently the aquifer is found between its top at 200 ft
and the interbed at 400 ft." (W9-1)
RespoDSe: The commentor is correct about the depths of perforations in the well shaft.
Because there are perforations above the current water table, it is possible that
contaminant~ are present around the injection well. in the subsurface "bedrock materials
above the aquifer.
Comment: One commentor suggested that contaminant.C! had been injected into the
vadose zone in a "dry area" approximately 20 ft above the aquifer. (W94) Because the
water level of the aquifer has dropped enhanced extraction technologies used as part of
the selected alternative will not be effective at decontaminatinf dry areas above the
aquifer. He concluded that coutaminants will remain after completion of the planned
remediation. (W9-2) The commentor wanted to know, "What can or will be done to
abate contamination in this dry, contaminatPii area above the 200-ft mark which the .
proposed techniques do not address?" (W9-6)
Respouse: Please. note that in light of new information made available in the year since
the proposed plan was issued, the agencies have reevaluated the remedia1 alternatives.
As a result of reevaluation of the remedial alternatives, the agencies have chosen
Alternative 4 as the selected remedy rather than Alternative 3. A description of the
selected remedy is given in Section 9 of the ROD. "
The selected alternative focuses on remediation of groundwater contaminant~ and the
secondary source in the TSF injection well and not on contamination that may be present
above the aquifer. If, during the course of the RDIRA, new information becomes
available that indicate contaminant.C! are present above the aquifer that pose an
1Jn!llcc.ept~ble risk to h~ health and the environment, the agencies" will reevaluate the
remPilia1 action in light of this new information.
Because contaminatm: will remain at the site above levels that would permit wilimited use
and unrestricted exposure, the NCP requires the agencies to review the remedial action
every 5 years. Thus, if the situation envisioned by the commentor arises, the agencies
are required by law to reevaluate the remedial action to ensure it remaiDs protective of
" human health and the environment.
All waste area groups at the INEL will perform comprehensive RIlFSs after each
operable unit at the WAG bas been evaluated. During the comprehensive RIIFS for
WAG 1, the agencies will reevaluate available data to ensure all c:onmmitmtm: at TAN are
or will be reJ"Qf'di!lltPii to levels that are protective of human health and the enviromnem.
-------
26.
Comment: A commentor asked, "If the waterline were to rise above the top perforation,
will a second "hotspot" and attendant contamination plume form? Will this require a
second abatement procedure?" (W9-5)
Response: The scenario of a rising waterline was not evaluated during the RIlFS phase
of this action. It is true that the well is perforated above the water table and as a result,
it is possible that contaminants are present around the injection well above the water
table. If the waterline were to rise into this area and if contaminant concentrations were
at high enough levels, it is possible that a "hotspot" and attendant plume could form.
The TSF Injection Well site will be subject to future reviews mandated by the FFAICO
and the CERCLA. If the scenario envisioned by the commentor occurs, it could be
evaluated as new information in one of these reviews. The RDIRA Work Plan requires
DOE to routinely evaluate data compiled from the WAG to determine any potential
WAG-specific problems that may become evident. In addition, the entire WAG 1 (which
includes OU l-Q7B) must undergo a comprehensive WAG-wide PlIFS which is scheduled
to begin July-August 1995. The CERCLA requires that any new information received
during the RDIRA phase of the cle<.nup be evalUated to ascertain its impact un the
selected remedial alternative. Because contaminants will remain at the site above levels
that allow for unlimited use and unrestricted exposure, the NCP requires the agencies to
review the remedial action every 5 years. Thus, if the scenario envisioned by the
commentor occurs, the agencies may determine that a second abatement procedure would
be neces~ary.
27.
Comment: One commentor recommended that if the treatment technology is Bot able to
extract enough strontium. to get (strontium-90 levels) down to drinking water standards,
then at least (the liquid effluent) should go into a lined evaporation pond. (1'3-3)
Another commentor shared this concern about using a lined evaporation pond. (T4-2)
Respouse: Instead of using a percolation pond to receive effluent, the agencies propose
that the treated effluent will be reinjected to the aquifer through wells designed for that
purpose. Since the extent of radionuclide contamination in the aquifer is limited to the
hotspot in the general vicinity of the TSF-05 injection well; it is expected that only the
portion of the remedy which focuses on the hotspot will need to address radionuclides.
Radionuclides will be treated at the hotspot to the extent practicable. The resins used in
the OU 1-7A Interim Action were not effective in removing cesium-137 from TAN
groundwater. Therefore, laboratory tests are currently being conducted to determine the
best commercially-available resins to remove cesium-137, strontium-90, and other
radionuclides from TAN groundwater. Additionally, studies are being conducted to
determine the most effective techniques (e.g., filtering, use of clarifiers) to remove
radiologically-contaminated particulate from the extracted groundwater. The agencies
will review the results of these studies in the fall of 1995 to develop trea~ent options for
radionuclides in the extracted groundwater. The agencies will then evaluate the various
treatment options within the context of the CERCLA threshold and balancing criteria to
assess their anticipated relative performance for this final remedy. The CERCLA
evaluation criteria are discussed in Section 8 of this ROD. If none of the active treat1nent
options effectively satisfy the evaluation criteria, a possible option could include no active
radionuclide removal from the extracted groundwater. Under this .worst case" option,
the extracted groundwater would be treated to remove VOCs only, and then reinjected
into the upgradient portion of the hotspot., In this way, the radiologically contaminated
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28.
29.
30.
31.
.'
groundwater would be hydraulically contained with extraction downgradient and
reinjection upgradient. The extent of radionuclide contamination would decrease over
time due to radioactive decay.
Comment: One commentor was concerned about the aerial dispersement problems
associated with using evaporation ponds. (T4-2)
Response: The selected alternative proposes to reinject treated groundwater directly into
the subsurface and will not use evaporation ponds. Therefore aerial dispersement
problems will not be an issue.
Comment: One commentor urged the use of steam over other surfactants because it
would be a cleaner operation. (T1-5)
Response: Because of the heterogeneity of the material disposed in the TSF-05 injection
well, the potential for contaminant mobilization, and the potential noncontactability of the
secondary source present within the hotspot, the proposal to use surfactant or steam has
been removeCL.
COMMENTS PERTAINING TO NO ACTION TRACK 1 SITES
General Tedmical Comments
Comment: Citing Table 3 (see page 14 of the Proposed Plan), a commentor asked,
"How can risk-based soil concentrations calculated from 1~ excess cancers be calculated
for noncarcinogens?" (W6-1) "How can you have greater than 1,000,000 ppm in soil?" .
He reminded the agencies of the risks other than cancer: aalte toxicity of solvents;
explosion and fire hazards; and hazards from instability of soils composed totally of
solvents? (W6-2) .
Respome: A hazard quotient (HQ) was determined for the noncarcinogen risk-based
concentrations and not a 1~ risk value. Table 3 differentiated carcinogenic and
noncarcinogenic contaminant!: by shading the carcinogenic contaminant~. The range of
contaminant concentrations shown in Table 3 resulted from the various sizes of the sites
evaluated. As a site gets smaller, greater concentrations of a contaminant are required to
pose a 1~ risk. Some sites that were evaluated were so small that essentially pure
contaminant (Le., 1,000,000 ppm) was needed to pose a risk.
The other risks mentioned are valid but were not considered the main scenarios for risk
at the sites to the potential occupational and future resident receptors. The process
agreed to by the agencies in evaluating these low probability hazard sites was to use a
conservative risk model that evaluated the effects of potential contaminant~ to humans
along the mosi sensitive and likely pathways shown in Table 3.
Comment: One commentor asked, "How can 46% benzene not be an inhalation
hazard?" (W6-3)
RespoDSe: Table 3 of the Proposed Plan does show that 46% (or 465,000 ppm) of
benzene to be an air inhalation hazard. The purpose of this table was to show the
required contaminant concentrations for the various pathways to pose a 1~ on HQ
> 1 risk (Le., risk-based soil concentrations). The actual benzene concentration detected
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33.
34.
at the site (0.55 ppm) is presented in the discussion for TSF-14. Since the actual benzene
at the site is several orders of magnitude below the risk-based soil concentrations.shown
in Table 3, the site was recommended for No Action. .
32.
Comment: One commentor was glad to see resolution of the "No Action" sites. (W1-5)
Response: Comment not~.
Comment: Two commentors disagreed about whether an indoor pathway should be.
evaluated in determining the risk posed to future residential users by surface contamimntts
at the No Action Track 1 Sites. One commentor felt that an indoor pathway should be
addressed because contaminants present in the soil would be in higher concentrations in a
basement because of the basement's lower barometric pressure. (1'2-3) The other
commentor stated that if contamination was present, it would not be deep enough to
create an exposure pathway to the residents. (T1-7)
Response: The risk assessment used for the 31 No Action Track 1 sites evaluated the
lisk posed by volatile inhalation in a conservative manner. The risk assessment
calculated the concentration of a specific volatile compound that would need to be present
in the site soils to pose a risk via the air volatilization pathway. This approach
conservatively assumes that the receptor would be exposed to site soil contaminated with
volatiles to a depth of 10 ft, and is not restricted to a location.
Comment: One commentor argued that the most dominant pathway for exposure to
surface contaminants is an outdoor pathway because the wind would stir up the surface
areas. (T1-8) Another commentor discounted the other's statement stating that the wind
decreases the surface concentrations of surface contaminants. High wind and fresh air
will move the contaminants away. (1'2-2)
Response: The effect of airborne contaminants was identified as a major pathway to the
Track 1 risk evaluation process and was considered during the 31-site assessment by
evaluating the air inhalation pathway for dust and air volatilization pathway for vapors.
The risk assessment used for the 31 No Action Track 1 sites evaluated the risk posed by
volatile inhalation in a conservative manner. The risk assessment calculated the
concenttation of a specific volatile compound that would need to be present in the site
soils to pose a risk via the air volatiJi7.ation pathway. This approach conservatively
assumes that the receptor would be exposed to the site soil contaminated with volatiles to
a depth of 10 ft and is not restricted to a location.
Comments Received on Loss-of-Fluid- Test a.OFTI-OS Fuel Tanks
35.
Comment: One commentor asked about the LOFT -05 tanks and associated piping and
whether there were plans to upgrade the system to current underground storage tank
(UST) stand8rds? "If so," he asked, "why not remove the old system and replace it with
a new, double-contained system with leak detection that can be relied upon?" (W7-1)
Response: The residual product in the LOFr-05 Fuel Tanks was removed in 1991
because they were no longer in use. However, the tanks were left in the ground in an
"active" status to maintain the building's capabilities because the future use for the LOFr
facility was uncertain. If, or when, the tanks are needed for use again, they will have to
-------
meet the current UST regulations. The final use of the tanks versus replacement or
complete removal will depend on the specific need of the future use.
Comments Received on TSF-39 ITransite (Asbestos) Contaminationl
36.
Comment: A commentor stated about the TSF-39 asbestos contamination site, "[it seems
as if it] would be relatively easy to clean up and dispose of the asbestos cement '.~ith
other asbestos at the Central Facilities Area (CFA) landfill." (W7-2)
Response: The TSF-39 Transite Site consists of small pieces of asbestos cement
(Transite) scattered over an approximately 400 x 2,5OO-ft area. The material is
continually being brought to the surface as a result of wind and water erosion. As a
result, multiple cleanup efforts would be required. Asbestos bound in cement does not
present an unacceptable risk and the expense of multiple cleanup efforts is not justified.
Comments Received on Water Reactor Research Test FaciIitv (WRRTF)..()2. -03 and -()6 (Waste
Water Disposal Sites)
37.
Comment: One commentor thought that the wastewater treatment or wastewater disposal
sites should be sampled and fully analyzed because the records are incomplete. (T4;-6)
Another commentor agreed that failing to sample the no action sites didn't sound to him
to be a very reasonable way to approach that kink of assessment. (T3-4) A third asked
"Why not take some samples and be sure?" (W7-3)
Respome: The DOE received additional sampling information from the WRRTF-OS
injection well that further increased the confidence that the WRRTF disposal pond sites
do not pose an unacceptable risk to either human health or the environment. The
WRRTF-05 injection wen was operational from 1959 to 1983, when it was abandoned
and replaced by the various WRRTF disposal ponds. The results from two rounds of
groundwater monitoring samples collected in May and July of 1994, from the former
WRRTF-05 injection well detected only Co-6O at concentrations greater than acceptable
risk levels. The 'presence of C~ in the WRRTF-05 injection well is from a known
one-time release in the mid-l960s, and not the result of routine disposal activities at the
WRRTF. Site investigations and radiological field surveys have not detected the presence
of Co-6O, or any other radionuclide, at the WRRTF disposal ponds.
COMMENTS DEEMED BEYOND THE SCOPE OF THE TSF INJECTION WELL AND
SURROUNDING GROUNDWATER CONTAMINATION AND NO ACTION SITES ROD
Comments and questions on a variety of subjects not specific to TSF Injection Well and
Surrounding Groundwater Contamination and No Action Sites were received during the public
comment period. Those comments addressed a general distrust of government, agencies,
statements questioning past management practices, concerns that the nuclear industry will not do
the "right" thing, and disagreement amongst public mPP.t1ng commentors. These out:-<>f-scope
comments are not responded to in this Responsiveness Summary. Information on these out-of-
scope commmts can be obtained from the INEL Public Affairs Office in 'Idaho Falls or at the
locallNEL offices in Pocatello, Twin Falls, and Boise.
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APPENDIX B
Public CommentlResponse List
t U
-------
Appendix B
Public. CommentlRespOnse List
Description of CommentlResponse List Index
The Public Comment/Response List Index was created to enable commemors and other
interested persons to locate the agencies' responses to individual public comments. All oral .
comments, as given at the public meetings, and all written comments, as submitted, were typed
into the attached index. Each commem was then subdivided and assigned a comment code.. The
codes indicate whether the comment was either written (W code) or taken from the public meeting
transcript (T code). The agencies tried to divide comments according to specific concerns, issues
or points ~e by the commemor.
Thirteen people submitted written comments (comments WI-W13) and four others gave oial
comments at the public meetings (comments TI-T4). Copies of oral and written comments
annotated with their respective comment codes are located in the Administrative Record. .
To locate a response to a specific individual's comments, look up the name of the
commentor, identify the specific comment you are looking for, then turn to the comment number
or page indicated in the Responsiveness Summary.
If, after reviewing the annotated comments in the administrative record, a reader wishes to
locate a response to a specific comment, he/she can use the comment code to locate a response as
well. The reader should idemify the comment code in the index, look up the commem and page
number of the response then turn to that page of the Responsiveness Summary.
Comments involving multiple issues were further subdivided and answers may appear in
more than one place in the Responsiveness Summary. This was done for only three of the
77 comments.
".
, ~
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,..
APPENDIX B
Public CommentlResponse List Index
Commentl Page
Code Commentor Comment Response No.
ilH;:::::::!::::iiiMl;::i::iit:!:::i_::I_:I:BmlIII1ill::1.¥III&\\li.81~tt.;1:&~:!~:::::::il::~::!:~:::::::i:::W:
Wl-l Joseph W. Henscheid Alternative #3 sounds reasonable. 22 A-17
WI-2 Joseph W. Henscheid However, this plan ought to recognize a couple 4 A-8
of other possible outcomes:
(1) What if (for whatever reason) the RAOs
change during Phase 1 (10 volume
removals)?
Wl-3 Joseph W. Henscheid (2) After Phase 1, what if you find that 4 A-8
progress towards achieving theRAOsis
minimal?
WI-4 Joseph W. Henscheid Seems like you might want to review the entire 5 A-8
approach rather than continuing pumping.
W2-1 Warren Barry I would favor Alternative #2. Limited Action 14 A-ll
Consisting of Control.
-
W2-2 Warren Barry The movement of the water in 40 years has been 14 A-ll
so slight that it would pose no threat to anyone
unless they proceeded to drill a well into the
area.
W2-3 Warren Barry This seems highly unlikely since the property 14 -A-ll
should be retained for its present purpose for a
number of years in the future.
W3-l Thomas J. Setter, M.D. I support Alternative #3 as the final alternative 22 A-17
for OU 1.{)7B.
W4-1 Randall c. Morris There is no evidence that the ecological risks 3 A-7
from the remediation activities themselves were
considered in the evaluation of alternatives. In
many cases, I'P.II1Miation activities designed to
reduce human health risks impose unacceptable
ecological risks. In this case, facility
construction and the disturbance to animal
PC;' -nations from operation of the facilities
impose risks on local populations. These should
be considered.
W5-1 Beverly Ferrell I believe the groundwater contamin:ttion should 6 A-9
be cleaned up as quickly as possible.
W5-2 Beverly Ferrell We should put no more nuclear waste in the site. OS
W5-3 Beverly Ferrell I am a victim of radiation releases near Hanford. OS
I lived directly across and on the river from
Rid1land (1947-1965).
W5-4 Beverly Ferrell I do not trust any government agency (~r OS
private) when nuclear waste is concemed.
W5-S Beverly Ferrell I do not believe members of the nuclear industry OS
will do the 8right8 thing.
WS-6 Beverly Ferrell Please do not send me any more propaganda. OS
WS-7 Beverly Ferrell I have lost all respect jor our government. OS
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Commentl Page
Code Commentor Comment Response No.
'iii:ii::iIIIIiiI:::i:iIii:iii:iii!ii::m_::ill_ii;..iMWiiilllilm:iiIIl1ll1l11Biiallliiiiiiiiiii:iiiiiiiiii:iiiiii:!:iii:iimi:iii:i:ii:iii
W8-l Guy Loomis I cannot accept the preferred alternative (#3) - 23 A-18
Air Stripping and Enhanced Extraction of
Hotspot with Aboveground Treatment for the
TAN Groundwater Contamination.
The dollars per cancer death averted are
unacceptable for any of the proposed scenarios.
The U.S. Government cannot afford to clean up
sites with these kinds of risks.
If one could show numbers like $lM per cancer
death, then the action would be justified.
Suggestion: Rcnder the scenario for residenti
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\~~
.!
I APPENDIX B I
Public Comment/Response List Index
Comment/ Page
Code Commentor Comment Response No.
::11i::1;:11::i1~;:::~1:::::::i:1:::11i1:i111~1:::i:i:iIIIlIIIIII_::::_it.:::lll:11.l:III!lIBI\IWII::::I:~I~1:::1:1t:1~1:~:i:::::1:::::1:1::11:1i1:1:111:::i::::1
W9-5 Rich Ravhill If the "hotspot" above the waterline will not be 26 A-20
decontatninatcd through the proposed
remediation and, due to increased future runoff
and replenishment, the water level rises above
the top perforation (180 ft or higher), will a
second "hotspot" and attendant contJlminJltion
plume form? Will this require a second
abatement procWure?
W9-6 Rich Ravhill What can/will be done to abate contJlminJltion in 25 A-19
this dry, contaminated area above the 200- ft
mark which the proposed techniques do not
address?
WI0-l Mazy Magleby If land use is considered, is the additional cost 0 15 A-12
Alternative 3 justified over Alternative 2?
WlO-2 Mazy Magleby Considering the flow rate of the aquifer, has the 16 A-12
concentration of CODtJlminJlnts at a point where
unrestricted access will be possible (likely) in the
future been calculated to justify the cost of
Alternative 3?
Wll-l Lee Tuott I support the preferred alternative. 22 A-17
Wll-2 Lee Tuott Please provide additional information on the 2 A-6
proposed injection of the treated groundwater to
the aquifer.
Wll-3 Lee Tuott How many injection wells would be equired? 17 A-13
r .
Where would they be sited so as to not influence
the pump/treat operations and dilute the existing
groundwater contJlminJltion?
Wll-4 Lee Tuott I support the concept of reinjection of treated 9 A-I0
groundwater due to the nonconsumptive use.
W12-1 Chuck Broscious The Environmental Defense Institute supports 20 A-IS
AlteT"'1ative 4 as outlined in the RIIFS with the
following caveats.
W12-2 Chuck Broscious Discharge of the "treated" groundwater that 20 A-15
contains 5r-90 greater than 300 pCiIL to an
unlined percolation pond violates the Clean
Water Act, Idaho Hazardous Waste Management
Act and, therefore, does not meet the Applicable
or ARARs.
It is hard to believe that a waste management
technique that has caused so much contJlminJltion
of the soil and groundwater at INEL is still used
today.
Discharging 5r-90 three hundred times the EPA
MCL of 8 pCilL so that it can again migrate
back into the aquifer is unconscionable.
, ~
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CommentJ Page
Code Commentor Comment Response No.
;i!i!!!:;!!!!i!!i!i!i:!::;::::::!i!;::;::!::!;::;:.l..lll_::;..iNi..:jllilil.:!!I.III}li1lB!!!~!.1:!!::!!!!!:::!Ii!i!:::::!::;i:!!!!:i!::!!i:i!:i:i
W12-3 Chuck Broscious As stated in previous comments, ED! advocates 21 A-16
tL.. use of a lined evaporation pond to receive
the "treated" discharge from the filtration system
at TAN.
The Remedial Investigation/Feasibility Study
Work Plan for Operable Unit l-07B, dated May
1992, indicates that approximately 35,000
gallons of TCE has been injected into the
aquifer. The RlIFS and the Proposed Plan both
state that the original uses of the TCE and PCE
cannot be identified due to lack of disposal
records and usage records. The compounds
existing in the aquif{r are not considered listed
wastes for these reasons.
By the vel)' nature of the chemicals used, the
typical uses of these chemicals for cleaning
operations and the fact that cleaning operations
were conducted at the Test Area North, DOE
should have concluded that TCE in the aquifer is
a listed waste.
During the RI process, EG&G personnel were
informed that substantial quantities of TCE were
used for solvent cleaning operations and
subsequently disposed of through the facility
drain system. This information was known by
the EG&G WAG 1 Manager in 1991 and
suppressed due to the difficulty of dealing with
the TCE in the aquifer as a listed waste.
It is widely known among the craft workers who
used TCE at the Test Area North that the bulk
of the TCE was used for cleaning operations
(Le., solvent usage).
It is inconceivable that the DOE and EG&G
Idaho personnel can assume that such massive
quantities of halogenated organics would have
been utilized for other purposes. Simply stating
that inadequate records exist to determine usage
is highly suspect.
It was not necessary and not usual to maintain
records for chemical usage before the passage of
recent environmental laws.
The Department of Energy should revisit the
issue of TCE usage at the Test Area North.
A confidential, independent survey of the current
and former craft workers and supervisors should
be conducted and the results directly reported to
DOE to eliminate the screening of information
performed by EG&G Idaho.
APPENDIX B
Public CommentlResponse List Index
W13-1 Anonymous
W13-2 Anonymous
W13-3 Anonymous
W13-4 Anonymous
W13-5 Anonymous
B-7
11
A-10
11
A-lO
11
A-lO
11
A-10
11
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I APPENDIX B I
Public CommentlResponse List Index
Commentl Page
Code Commentor Comment Response No.
::::I::::::::!:::::::::::::::!:::::::~::::::I::::f:::::_:j:II_!:::.gt!£d!:::II]I.:::lllmm.lt!.llM:t~::::::::!::I::::::::::::::::::::::::::::::::!:!:::::::::::
W13-6 Anonymous The Remedial Investigation/Feasibility Study 12 A-lO
Work Plan for Operable Unit l-07B, dated May
1992, indicates that 55 ft of sediment and sludge
was removed from the Injection Well. It is true
that some of the contamination was removed
from the well. However, due to lack of funding
the task was terminated before the remainder of
the sludge was removed.
W13-7 Anonymous The cleanup operation was not completed in 12 A-tO
accordance with the Work Package
documentation and the cleanup instructions.
Specifically, the well was to be flushed until the
effluent was clear.
W13-8 Anonymous At the termination of the work, the effluent was 12 A-IO
still laden with contaminated sediment and
sludge.
W13-9 Anonymous The equipment used to perform the cleanup 13 A-ll
operation was abandoned in place. at the
instruction of the EG&G Project Manager. The
equipment was removed months later after the
EG&G Project Manager had retired.
W13-l0 Anonymous When the pump and piping abandoned in the 13 A-ll
well was later removed, external contamination
(on the outside of the pump and piping) was
flushed back down the well during steam
cleaning operations, at the direction of the
EG&G Project Manager. The contaminated
liquid, which should have been disposed of as
mixed waste, was flushed back into the aquifer.
WI3-11 Anonymous DOE should consider additional action to remov~ 13 A-ll
the remaining sludge tram the well and
determine what action to consider for removal of
the contaminants flushed back down the well.
W13-12 Anonymous The proposed pump and treat system design does 13 A-ll
not consider that substantial residual
contamination exists in well casing and at the
bonom of the well.
-'
.
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Code
Commentor
~~tJ~lli~~i~~~~~ii*~~~1~1~~~1~~~f~~l*1gg~~~;~:~~;~;:;~;~:::::~:;::L;::.x~.:....... ..'.','.',.. .. ','"
Tl-l C. E. White
TI-2 C. E. White
TI-3 C. E. White
TI-4 C. E. White
APPENDIX B
Public CommentIResponse List Index
Comment
"""""""".'.:~:~::~~IIi&1l_iT.IIE_&~mr~i~~~~f:~~~~~l~~it~~~t~!
A-17
What you accomplish with remedial
Alternative No.3 would be the preferred
one.
It certainly appears from anything that you
can come up with from the study, it would
alleviate any major problems.
I can't see where there would be worth
spending all that additional money to do
[Alternative] 4 when you don't really.
accomplish that much more out of it. Your
rel.!tionship between ",hat's accomplished
against what is spent. The closer you get to
[Alternative] 4 from [Alternative] 3, the
more the ratio changes and you get less for
your money. Not that money should be the
total alternative or total basis of the
alternative, but with what you get out of
[Alternative] 3, certainly seems to solve the
problem, unless, in the future it's discovered
that [Alternative] 3 is not doing what we
thought it was going to do. Let's put it that
way.
One of your surprises was finding some
things which you didn't know were there.
Well, who knows, maybe in the future,
although you'l1 take care of those now, who
knows in the future if something else comes
up in their little head, and you have to
reas~ ~ ,>s something.
But, to me, the Remedial No.3 would be
the way to go, and it would be, I think,
enough protection to satisfy most anybody
that I've ever talked to about it.
B-9
Comment!
Response
22
18
19
22
Page
No.
A-14
A-14
A-17
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Comment/ Page
Code Commentor Comment Response No.
:::::::;::::::::::::;:;t::::;:I::::::'::::::t::::::;::::::I~:::;I_:!:.II~:j!II::I.::::.I~l\i1ll!~![j.:;::I::::::;j=j:::::;'i::;::::i;::;:::::::!!:;;:::::::;:::;:;i:
TI-5 C. E. White I would like to add one more item to what I 29 A-2I
just said. We were discussing the injection
of other substances to try to, let's ~ay,
loosen up some of the things that are in that
plume, the two were the steam and the other
so-called soapy alternative.
Certainly the steam, if it works the way it
works in the oil the fields, would be a much
cleaner type operation to go into' rather than
injecting some other item into the ground
and then have to pull that out, soap or
wb~tever that they drove into this thing, so
I'm assuming that in looking at these that
the steam would be looked at first, am I
right?
I guess I agree with Mr. White that the
Alternative No.3 is probably the best for
your cost ratio, and groundwater is very
difficult to clean up. It's a difficult problem
and cleaning up the contaminated sediments
and residuals, I think, is your best
alternative as opposed to going after the
entire plume.
It's real encouraging to see improvements in
the public literature that's coming out, to
see, you know, data that is-not only states
. the maximum observed concentrations, but
besides that, the drinking water standard.
And, you know, that is a significant change
from the way things were don~ in the past.
And it's very helpful to have the
information presented in that way. I think
it's a lot more candid and I would put it as a
significant improvement.
APPENDIX B
Public Comment/Response List Index
v
T2-1 Steve Novak
T3-I Chuck Broscious
. .
'-'
,
B-IO
22
A-I?
I
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I ,
I Comment! Page
Code Commentor Comment Response No.
I::!:!::!i:!i:::::Ii:!:!!!::i:::::!:!!::~i::i::!::!::ii::iillli!il_I::i!II_!i!II!I.ii:.I~Jli.li::!I{I.!::1:!:::iii:i;ii:i:i::i:ii::::ii::iii::i:::!ii:i::::i!:::~:!iii::!::
T3-2 Chuck Broscious The one reservation that I have about the 20 A-IS
way the treated water is being discharged is
that if, in fact, it has the concentrations of
cesium-or Strontium-90 at 30 picocuries
per liter, which is-I'm sorry, 300
picocuries per liter, which is almost 300
times the drinking ;vater standard, being
discharged into something that is universally
recognized as a failed inadequate waste
management approach, being the percolation
pond, is just really distressing to see that
that kind of continued practice is going on.
I would much rather see, as we've
recommended in our written comments, that
if indeed the treatment technology is not
able to extract enough of the strontium to
get it down to drinking water standards,
then at least it should go into a lined
evaporation pond.
I guess what concerns me-I'iD. like Chuck,
I appreciate the more open nature in the way
that the infonnation is being provided these
days and the more complete nature of the
data that's being provided.
And similar to Chuck, I'm concerned about
evaporation ponds, and not only for
percolation reasons, but also for aerial
dispersement problems that may occur if
there are evaporation ponds. I'm not sure
that those are addr~sed adequately any
place or that the data is available,
knowledge is available, to know exactly
what's going to happen with that stuff in
terms of aerial dispersement.
But in terms of the characterization of the
site and the extent of contamination of this
site, I have some concerns about that as
well.
In terms of the fact that just looking at your
sampling scheme, for instance, for this
water plume, I have a hard time seeing how
you can have a high level or degree of
confidence that you have adequately
described the degree of contamination there.
...-..'
H',\. '
". .
T3-3 Chuck Broscious
T4-1 Tom Dechert
T4-2 Tom Dechert
T4-3 Tom Dechert
APPENDIX B
Public CommentlResponse List Index
27
A-20
I
A-6
27,28
A-20
A-21
10
A-IO
10
A-IO
-------
Comment! Page
Code Commentor Comment Response No.
i:!:!::::!~!:i:i::!::!;:i;:!i!:!::i:i:i::::::!:!:::::~::i!:!:!ii:I8I:!i!I_:::!._ii~:II;::I.i::.IVII}lI_::::1i1!~~1!!i::!::::ii!:~ii:::!::i::~i~!::1i:i~i:!:::ii::!!!~:!!!:!::i:
T4-3 Tom Dechert And I think by vinue of the fact that you're
(Cont.) getting stuff back out of the injection well
that you haven't seen before, you're seeing
things that are surprising you as you go
along, is an indication that there is some
lack of understanding, I think, of degree of
contamination in ~he aquifer, and not only
that, but how the aquifer works at that site,
or any place else, as far as that goes, under
the INEL.
I'm not fully convinced that-what should I
say-well, fIrst off, having to do with the
interbeds, that the characterization of those
interbeds as you have described them and
they were also described to me outside of
this meeting can fully explain-if we're
talking about basalt-what's going on with
the containment of the contaminants that are
down there.
In other words, I would have-I just have a
feeling that there's more to the interbeds,
the silts and th~ clays, that are occurring in
the aquifer, than you have a good handle
on.
And it disturbs me, I guess, that the models
you use when you're looking at those or
when you are describing those, what's going
to happen with these plumes of these-the
movement of contaminants in the future are
based on assumptions of the clays, the silts
and the basalts in the aquifers that I don't
think are very well documented or very well
substantiated in your database.
T4-4 Tom Dechert
. "
."
APPENDIX B
Public CommentlResponse List Index
B-12
10
-------
Comment! Page
Code Commentor Comment Response No.
:ilii!:~]:t1;M:;;;:r1~;~1!:~:iI!IIilt.~._i_.~1_1II.tf.illil:l.I_lli~:f.~~~tt~~::~;,m:i
Wl-5 Joseph W. Henscheid I'm glad to see your resolution of the "No Action" 32 A-22
sites.
W6-1 Donald Brice Table 3, Page 14. How can risk-based soil 30 A-21
concentrations calculated from 1 Q"6 excess cancers
be calculated for noncarcinogens?
W6-2 Donald Brice Also, how can you have greater than one million 30 A-21
pans per million solvent in soil?
There are risks other than cancer. What about
acute toxicity of solvents, explosion and fire
hazard, and the hazard from instability of soils
composed totally of solvents?
W6-3 Donald Brice How can 46 % benzene not be an inhalation hazard? 31 A-21
W7-1 Alan Merritt LOFf -os . ."tanks and assoc. piping remain in 35 A-22
place pending future use." Are you going to
upgrade this system to current UST standards? If
so, are you doing the equivalent of putting a new
engine into a 40-year-old truck? Why not remove
this old system and replace with a new double-
contained system with leak detection that can be
relied upon?
W7-2 Alan Merritt TSF-39' sounds like this would be relatively easy to 36 A-23
clean up and dispose of the asbestos cement with
other asbestos at the CF A landfill.
W7-3 Alan Merritt WRRTF-02-Q3-<>6 "Although no soil sampling has 37 A-23
been conducted . " Why not collect some
samples and be sure?
, I
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"
Comment! Page
Code Commentor Comment Response No.
m:jIrrt.\jI~:1:j1j:!:jmHf!;:iij:i:r,_;111_~.I!I!.i:.~III~1II.mllllRll\.:II1:fu1~~1j*Mm;;;;ii;jj:;::1~Mj!
TI-6 C. E. White I can't agree totally with my friend over here about OS
the house basement, what have you.
TI-7 C. E. White Most of the contamination-I'm even going as far 33 A-22
as to say all of the contamination that was found on
the ground or in that area, was not of a very deep
~e It ~ &roba~6, abQve f&ur or fiv3 feet.
ererore, y u go wn mto e groun , you're
not creating a dominant path, I don't think.
TI-8 c. E. White I think your more dominant path is the way it's 34 A-22
looked at because you're living in Idaho, and if you
live in Idaho, you've got the wind. And this is
going to be the greatest, I think, path of
contaminant would be from the surface areas that
would be stirred up by the wind or whatever.
Tl-9 c. E. White I can't-I agree with most of your other things, but OS
I can't with that.
1'2-2 Steve Novak I feel that the indoor pathway should be addressed 34 A-22
as well as the outdoor pathway. For several
reasons. And I'll address Mr. White's comments.
The fact that there is a lot of wind in Idaho
probably decreases the outdoor pathway even more,
because the concentration on the outdoor pathway
most likely would be lower due to the fact that
there is high wind, fresh air will bring and move
CODtaminant~ away.
1'2-3 Steve Novak As far as the basement scenario, contaminant~ not 33 A-22
only go through the basement, they go through the
walls and the sides of the basement as well. So,
usually, contamination anywhere from one to ten
feet was a concern when you have a basement
because it gets sucked into the basement in the
pressure through the outside and the basement.
1'2-4 Steve Novak There is a large concern of radon. It's also a OS
concern of volatiles: benzene, toluene,
ethylbenzene, especially benzene which is more
toxic than the other contaminant.c;.
T3-4 Chuck Broscious That was what I had underlined, too, the fact that it 37 A-23
says here "although no soil sampling was
conducted, " "no soil sampling conducted, "
"although no soil sampling conducted," and it goes
on and on. You know, good gosh, that doesn't
sound to me like a very reasonable way to approach
that kind of assessment.
,"
(j
.
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Code
Commentor
Comment! Page
Comment Response No.
::::;X::::;:].!;_.j.f:I.~1II.1!.1:;1:1~11!f!.iltt.J;m1t;M;ili~ii!.i.ili1f;!:i.;i:n
I just, as a comment, I think that those wastewater 37 A-23
treattnent or wastewater disposal sites, the soils
should be sampled and fully analyzed, because I
think the records are, you know, incomplete.
T4-6
;~~~~j~~1~~~1~~1~~~~~~1~~1*i~~1~jj~~jfii~11~11t::~.
Tom Dechert
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APPENDIX C
Admini~ative Record Index
4.1
..)
-------
File Number
11.7
R.U.!
<.:
Appendix C
Admini~ative Record
Test Area North Injection Well 07114/94
Technical Evaluation
Document #: 5694
Title: Letter Report-Technical Evaluation of the TAN on 1-07B RIlFS and Proposed
~an .
GeoTrans, Inc.
EG&G Idaho, Inc.
11/30/93
Author:
Recipient:
Date:
EPA Comments
Document #: 5341
Title: Review Comments for Draft Remedial Investigation Report W / Addenda for the
Test Area North Groundwater Operable Unit at the INEL
Author: Liverman, E.
Recipient: Green, L.
Date: . 07/09/93
Document #: 5573 .
Title: Review of Draft Remedial InvestigationIFeasibiIity Study for the Test Area North
Groundwater operable Unit 1-07B
Author: Liverman, E.
Recipient: Williams, A. C.
Date: 11/05/93
Document #: 5682
Title: Resolution of EPA'g Comments on TAN OU 1-07B Draft Final RIlFS
Author: Pierre, W.
Recipient: Lyle, J. L.
Date: 01/26/94
Document #: 5697 .
Title: Review of Draft Final Remedial InvestigationIFeasibility Study for the Test Area
North Groundwater Operable Unit 1-07B
Author: Liverman,E.
Recipient: Green, L.
Date: 01112/94
Document #: 5698 . .
Title: Review of Draft Proposed Plan for the Test Area North Groundwater Operable
Unit l-07B
Lwerman,E. .
Harelson, D. B., English, M.
03/28/94
Author:
Recipient:
Date:
-------
Test Area North Injection Well 07/14/94
File Number
AR12.2
IDHW Comments
Author:
Recipient:
Date:
Document #: 5340 .
Title:. Review of the Draft Remedial Investigation Report for Operable Unit (OU) 1-07B
Author: English, M.
Recipient: Green, L.
Date: 07/02/93
Document #: 5574
Title: Review of the Draft Remedial InvestigationIFeasibility Study for Operable
Unit 1-07B
Author: English, M.
Recipient: Williams, A. C.
Date: 10/29/93
Document #: 5683
Title: Review of "he Draft Proposed Plan Operable Unit (OU) 1-07B
Author: English,M.
Recipient: Green, L.
Date: 03/14/94
Document #: 5699
Title: Review of the Draft Final Remedial Investigation Feasibility Study (RIIFS) for
Operable Unit (OU) 1-07B
.English, M.
Green,L.
01/11/94
AR12.4
Document #: 5684 .
Title: TAN OU l-07B Draft Final RIfFS Report
Author: Nygard, D.
Recipient: Lyle, J. L.; Pierre, W.
Date: 01/28/94
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