EPA Superfund Record of Decision: Idaho National Engineering Laboratory (usdoe) EPA ID: ID4890008952 OU 01 Idaho Falls ID 08/18/1995


                                    EPA/ROD/R10-95/120
                                    1995
EPA Superfund
     Record of Decision:
     IDAHO NATIONAL ENGINEERING LABORATORY
     (USDOE)
     EPA ID: ID4890008952
     OU01
     IDAHO FALLS, ID
     08/18/1995

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                                                    August 4,  1995

         
                               Operable Unit 1-07B
                                Waste Area Group 1
                         Idaho National Engineering Laboratory
                                Idaho Falls, Idaho

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DECLARATION OF THE RECORD OF DECISION

Site Name and Location

Technical Support Facility Injection Well (TSF-05) and
Surrounding Groundwater Contamination (TSF-23)))0perable Unit (OU) 1-07B
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

This decision document presents the selected final remedial action for OU 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 reguire no action. These actions were chosen in accordance with the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) as amended by the Super
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 (EPA) 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 OU 1-07B, 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 environment from future use of water taken from the TSF-05
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 EPA 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 contaminated groundwater by future residents at
this site. The contaminants identified at concentrations above risk-based levels in the groundwater are
organic compounds trichloroethene (TCE), cis- and trans-1,2-dichloroethene (DCE), and tetrachloroethene
(PCE), and radionuclides strontium-90, tritium, cesium-137, and uranium-234. Operable Unit 1-07B is defined
as that part of the groundwater beneath TAN that has, or is expected to have, concentrations of TCE above the
Safe Drinking Water maximum contaminant level (MCL) of 5 jlg/L. Trichloroethene is being used as the
indicator constituent for defining the groundwater plume because it is the most widely distributed
contaminant of concern (COG) in the TAN groundwater. The selected remedial action for OU 1-07B is
groundwater plume extraction and treatment of the greater than 25 jlg/L TCE plume and hydraulic containment
of the TSF-05 Injection Well hotspot with aboveground treatment. The reasonable timeframe for restoration of
the aguifer 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 contaminants. The selected remedial action will be
conducted in three phases:

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• 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
surging and stressing the well for 15 months 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 contaminated groundwater will be within the acceptable range of 10-4 to 10-6. 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) operations
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 aguifer 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 10-4 to 10-6. 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
containing COG concentrations greater than MCLs or 10-4 to 10-6 risk-based concentrations for
contaminants without MCLs. Institutional controls shall be maintained until COG concentrations
fall below MCLs or 10-4 to 10-6 risk-based concentrations for contaminants without MCLs.

The purpose of Phase B is to remove, treat, or contain the contaminants 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 Wavier (TIW) will be pursued for the source area. If a TIW is granted, an
alternative remedial strategy to prevent migration of contaminants beyond the source area will be necessary.
The actions required in this ROD are not inconsistent with foreseeable alternative remedial strategies.

Statutory Determination

The selected remedy for OU 1-07B 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 this
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.
      John Wilcynski                                 Date
      Manager,
      Department of Energy Idaho Operations Office

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.
      Chuck Clarke                                  Date
      Regional Administrator, Region 10
      Environmental Protection Agency

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.
      Wallace N. Cory
      Administrator
      Division of Environmental Quality
      Idaho Department of Health and Welfare

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CONTENTS

DECLARATION OF THE RECORD OF DECISION iii

ACRONYMS and ABBREVIATIONS xi

OPERABLE UNIT 1-07B DECISION SUMMARY 1

1. SITE NAME, LOCATION, AND DESCRIPTION 1
2 . SITE HISTORY AND ENFORCEMENT ACTIONS 3
3. HIGHLIGHTS OF COMMUNITY PARTICIPATION 5
4 . SCOPE AND ROLE OF OPERABLE UNIT 6
5 . SUMMARY OF SITE CHARACTERISTICS 7
6. SUMMARY OF SITE RISKS 17
7 . DESCRIPTION OF ALTERNATIVES 23
8 . SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 26
9. SELECTED REMEDY 31
10. STATUTORY DETERMINATIONS 40
11. DOCUMENTATION OF SIGNIFICANT CHANGES 45
12. TEST AREA NORTH TRACK 1 NO ACTION SITES 46

APPENDIX A))RESPONSIVENESS SUMMARY A-I
APPENDIX B))PUBLIC COMMENT/RESPONSE LIST B-l
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-05 Injection Wei 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 estimated 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-05 Injection Well and Interim Action Wells
TAN-25 and TAN-26 12
5-3. Validated results from March and June 1994 quarterly sampling and analysis showing the
range of contaminant 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. Estimated costs associated with remediation 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 emission rate limits for OU 1-07B 34
10-1. Summary of ARARs for Alternative 4 42

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                           ACRONYMS and ABBREVIATIONS
AAC       acceptable air concentration for noncarcinogens
AACC      acceptable air concentrations for carcinogens
AMP       Aircraft Nuclear Propulsion
ARARs     applicable or relevant and appropriate requirements
BLM       Bureau of Land Management
bis       below land surface
CERCLA    Comprehensive Environmental Response, Compensation, and Liability Act
CFA       Central Facilities Area
CFR       Code of Federal Regulations
COG       contaminant of concern
COCA      Consent Order and Compliance Agreement
CTF       Containment Test Facility
DCE       1,2-dichloroethene
DOE       U.S. Department of Energy
EPA       U.S. Environmental Protection Agency
FET       final engine test
FFA/CO    Federal Facility Agreement and Consent Order
FS        feasibility study
gpm       gallons per minute
GWTF      Groundwater Treatment Facility
HQ        hazard quotient
IDAPA     Idaho Administrative Procedures Act
IDHW      Idaho Department of Health and Welfare
IET       Initial Engine Test
INEL      Idaho National Engineering Laboratory
LDR       land disposal restriction
LOFT      Loss-of-Fluid Test
MCL       maximum contaminant level
NCP       National Oil and Hazardous Substances Pollution Contingency Plan
O&M       operation and maintenance
OU        operable unit
PCE       tetrachloroethene
pCi/L     picocuries per liter
ppm       parts per million
ppmw      parts per million by weight
RAO       remedial action objective
RCRA      Resource Conservation and Recovery Act
RI        remedial investigation
ROD       Record of Decision
SMC       Specific Manufacturing Capability
TAN       Test Area North
TCE       trichloroethene (also known as trichloroethylene)
TIW       Technical Impracticability Waiver
TSF       Technical Support Facility
VOC       volatile organic compound
WAG       Waste Area Group
WRRTF     Water Reactor Research Test Facility

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OPERABLE UNIT 1-07B

DECISION SUMMARY

1.  SITE NAME, LOCATION, AND DESCRIPTION

The Idaho National Engineering Laboratory  (INEL) is a 2,305 km2  (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 and Mud Lake [19 km  (12 mi) east]; Arco [35 km  (22 mi) west]; Blackfoot  [61 km  (38 mi) southeast];
Idaho Falls [79 km  (49 mi) east]; and Pocatello [108 km  (67 mi) southeast].

The Test Area North  (TAN) complex is located approximately 80 km  (50 mi) northwest of Idaho Falls in the
northern portion of the INEL and extends over an area of approximately 30 km2  (12 mi2) (Figure 1-1).  The
Technical Support Facility (TSF) is centrally 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 corner 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  (CTE)  (formerly the Loss-of-Fluid Test  (LOFT),
Facility, the Initial Engine Test (IET) 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 km2  (500 mi2) buffer zone used for cattle and sheep grazing.

The INEL has semidesert characteristics with hot summers and cold winters.  Normal annual precipitation is 23
cm  (9.1 in.)  per year, with estimated evapotranspiration of 15 to 23 cm  (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 depleted
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
mammals.  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
(Haliaeetus leucocephalus), long-billed curlew  (Numenius americanus),  and the loggerhead shrike (Lanius
ludovicianus).  In addition,  the Townsend's big-eared bat  (Plecotus townsendii), and pygmy rabbit
(Brachylagus idahoensis) are listed by the U.S. Fish and Wildlife Service as candidate species for
consideration as threatened or endangered species.   The ringneck 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.




2.  SITE HISTORY AND ENFORCEMENT ACTIONS

2.1  Site History

Operations at TAN were initiated in the early 1950s to support the U.S. Air Force aircraft nuclear propulsion
(AMP) project.  The objectives of the AMP 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,
IET, Low Power Test Facility/Experimental Beryllium Oxide Reactor  (now WRRTF), and LOFT  (now the SMC/CTF).

The principal source of groundwater contamination at TAN is the TSF-05 Injection Well located in the
southwest corner of TSF  (see Figure 1-2).  The TSF-05 Injection Well was used from 1953 to 1972 to dispose of
TAN liguid wastes into the fractured basalt of the Snake River Plain Aguifer. 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 simulating accidents
involving the loss of coolant from nuclear reactors.

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Releases to TAN groundwater were first identified in 1987 when low levels of the organic compounds
trichloroethene (TCE) and tetrachloroethene (PCE) were detected in the production wells that supply drinking
water to TSF. To mitigate potential risks to personnel at TAN, an air sparging system was installed on the
drinking water supply system. Subsequent sampling of TAN aguifer 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-90 has been detected above
drinking 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 effort removed process sludge from the bottom 17 m (55 ft) of the TSF-05 Injection Well.
Analytical results showed that the sludge contained high levels of organic contaminants (2% TCE) and
radionuclides.

2.2 Enforcement

The TSF-05 Injection Well and the groundwater contamination at TAN were first identified and evaluated in
accordance with the Resource 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
(CFR) 300.425(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 (FFA/CO), pursuant to
CERCLA, in December 1991. The FFA/CO superseded the COCA and established a procedural framework for a agency
coordination and a schedule for all CERCLA activities conducted at the INEL.

At the TAN groundwater release site, pursuant to the FFA/CO Action Plan, DOE implemented an Interim Action
and a remedial investigation (RI)/feasibility study (FS) to characterize the extent of contamination, to
estimate human health and environmental risks, and to evaluate potential response actions. The Interim
Action and RI/FS, designated as Operable Unit (OU) 1-07A and 1-07B, 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-05 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 OU 1-07A Interim Action
included

• Extracting contaminated groundwater from TSF-05 Injection Well and nearby groundwater
monitoring wells capable of capturing contaminated groundwater.

• 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 wells 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.

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       •      Modifying the existing TAN disposal pond to receive the treated groundwater and ensure
              discharge water guality does not further degrade the underlying Snake River Plain Aguifer
              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 minimize exposure to releases of hazardous substances during remediation.

The purpose of this ROD is to document the final remedial action for OU 1-07B.

3.  HIGHLIGHTS 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 decision making process under CERCLA and the National Oil and
Hazardous Substances Pollution Contingency Plan  (NCP)   (40 CFR Part 300) and to ensure that appropriate public
participation continues under the FFA/CO.

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
alternative source of drinking water for workers at TAN and the scheduled installation of an air sparging
system to remove volatile organic  (VOCs) 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 newspaper:  The
Post Register (Idaho Falls), The Idaho State Journal (Pocatello), Twin Falls Times News  (Twin Falls), Idaho
Statesman (Boise), The Lewiston Morning Tribune,   (Lewiston) Idaho Free Press  (Nampa),  South Idaho Press
(Burley), and Moscow-Pullman Daily News  (Moscow).

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 copies 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 guestions, 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 Information 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 prepared to address public comments as part of 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 subseguent 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 available 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, and 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

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information repositories, and will be provided to the public upon request.

4. SCOPE AND ROIiE 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 1-07A. The groundwater in the immediate vicinity of TAN, which has TCE concentrations
greater than the MCL of 5 micrograms per liter (]lg/L), has been designated 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 contaminants including TCE, PCE, and DCE and
several radionuclides including Sr-90, 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 absorption 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 (bis) near the TSF-05 Injection
Well, has been encountered in only about 50% of the wells drilled deep enough at TAN to 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) bis near the TSF-05 Injection Well, is considered
laterally continuous throughout the TAN region. This is supported by (a) geological data obtain during
borehole drilling, (b) basalt flow age 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 sedimentary
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 contaminants in the aguifer.

5.2 Hydrology

The Snake River Plain Aguifer, one of the largest and most productive groundwater resources in the United
States, underlies the INEL. The aguifer is listed as a Class I aguifer, and EPA has designated it as a sole
source aguifer. The Snake River Plain Aguifer is defined as the series of saturated basalt flows and
interlayered pyroclastic and sedimentary materials underlying the eastern Snake River Plain. The aguifer is
approximately 325 km (200 mi) long, 65 to 95 km (40 to 60 mi) wide, and covers an area of approximately
25,000 km2 (9,600 mi2). As much as 2.5 x 1012 m3 (2 billion acre ! ft) of water may be stored in the
aguifer))approximately 6.2 x 1011 m3 (500 million acre ! ft) of which are recoverable. The aguifer
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 Aguifer is to the south-southwest; locally, the direction of

-------
groundwater flow is affected by recharge from rivers, surface water spreading areas, pumping of the aguifer,
and heterogeneities in the aguifer. Figure 5-1 is a regional water table map of the TAN area showing the
inferred direction of groundwater flow. The hydraulic gradient for the regional aguifer in the vicinity of
TAN is about 0.2 m/km (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-05 Injection Well) is strong and may cause major flow disruptions or times of flow reversal
within the aguifer 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)-l and FET-2] are located
near LOFT, west of the TSF, and are outside of the OU 1-07B groundwater contaminant plume. The production
wells TAN-1 and TAN-2 are located on the north side of TSF and supply water for operations at TSF. Low
levels (1-8 jlg/L) of TCE have been detected in wells TAN-1 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 Contamination

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
environmental 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-05 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 TSP-05 Injection Well is the source of contamination 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 Final Report with Addenda for the Test Area North Groundwater Operable Unit 1-07B at
the Idaho National Engineering Laboratory, Volume 1, EGG-ER-10643, January 1994, which is located in the
Administrative Record.

The TSF-05 Injection Well was drilled in 1953 to a depth of 93 m (310 ft) to dispose of liguid effluent
generated from the ANP project. The TSF-05 Injection Well has a 30-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 305 ft) 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 disposal 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 to the aguifer 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 guality 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
radionuclides have been detected as a result of several sampling efforts by the U.S. Geological Survey and
DOE. Groundwater guality data from sampling events performed between 1988 and 1991 showed TCE concentrations
at the TSF-05 wellhead from 4,100 to 28,000 jlg/L.

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, aguifer testing, and sampling suggests that
the majority of contamination is limited to the uppermost portion of the aguifer underlying TAN, and that the
Q-R interbed represents a hydrologic barrier that separates the upper aguifer above the Q-R interbed from
lower aguifers 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) of
VOCs 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 ug/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 nonagueous phase liguids or small pools (residual saturation) in dead-end
fractures or on basalt flowtops.  The TSF-05 hotspot is defined as including the secondary source and highly
contaminated groundwater  (i.e., with TCE concentrations greater than 5,000 jlg/L) in the immediate vicinity
of the TSF-05 Injection Well.  Evidence does not support the existence of a free phase dense nonagueous
phase liguid.

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
contaminants is mainly limited to the area in the immediate vicinity of the TSF-05 Injection Well.  A full
description of contaminant concentrations in aguifer 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 TSE-05 Injection Well in June 1993
(Table 5-2)  showed TCE (290-17,000 ]lg/L), DCE  (180-9,300 ]lg/L), Cs-137  [less  than the  detection  limit-2,030
picocuries per liter (pCi/L)],  U-234 (17 pCi/L), and Sr-90  (8.2-630 pCi/L), and PCE (5-39 ]lg/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.

Analytical results from groundwater samples collected for the first and second guarters of 1994  for TAN-25,
TAN-26, and the TSF-05 Injection Well during the OU 1-07A Interim Action are presented in Table  5-3.  Upon
comparison of contaminant concentrations detected in wells TSF-05, TAN-25, and TAN-26, it is apparent that
the 1992 RI, June 1993, and guarterly Interim Action results are generally consistent.  However,  it should be
noted that contaminant concentrations detected during the Interim Action have varied depending on pumping
rate.

-------
Table 5-1. Contaminants of concern and range of concentrations in the Test Area North groundwater.a
Chemical

Organic compounds (jlg/L)

PCE

TCE

cis-l,2-DCE

trans-l,2-DCE

Radionuclides (pCi/L)

Sr-90

H-3

Cs-137

U-234
TAN
monitoring wells
TAN
production wells
<1-1,400

-------
Table 5-2. Results of June 1993 sampling of TSF-05 Injection Well and Interim Action Wells TAN-25 and TAN-26.
TSF-05
Injection Well
20-22
5, 900-11, OOOJb
6, -00-9, 300J
520-630
18,700-18,800
2,010-2,030
17
TAN-25
Monitoring Well
39
17,000
4,800
380
14,200
147
10
TAN-26
Monitoring
Well
5J-15J
290-670
180-340
8.2-8.6
4,700-4,800
<30c
2.3-3.4
MCLa
5
5
70
8
20,000
119
30
Chemical

Organic Compounds (]lg/L)

PCE

TCE

Total DCE

Radionuclides (pCi/L)

Sr-90

H-3

Cs-137

U-234

a. 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 mrem/yr effective dose eguivalent to the public, assuming lifetime intake of 2
L/day of water.

b. The "J" 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
TSF-05
Injection Well
TAN-25
Monitoring Well
TAN-26
Monitoring Well
MCLb
Contaminant

Organic Compounds (]lg/L)

PCE

TCE

cis-l,2-DCE

trans-l,2-DCE

Oil and grease (mg/L)

Radionuclides

Strontium-90c

Tritium

Uranium-234

Uranium-235

Uranium-238

Americium-241/
Plutonium-238

Plutonium-239/240

Cesium-137

Cobalt-60

a. Key: )) = not sampled; < indicates less than detection limit.

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 mrem/yr effective dose eguivalent to the public, assuming lifetime intake of 2
L/day 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 y.g/L for the
March 1994 analysis and 200 jlg/L for the June 1994 analysis.

d. A duplicate sample of the 46.3 was taken, which was <5 mg/L.

e. Range includes only unfiltered Sr-90 samples.

f. EPA (1977), Primary Drinking Water Standard.

110
12,000-32,000
3,200-7,500
1,300-3,900
<5-10
530-1,880
14,900-15,300
5.2-7.7
<0.2
<0.1-0.43
<0.2
<0.2
1, 600-2,150
23
<200c
5,900-9,300
890-3,500
450-2,000
<5-7.1
380-440
7,500-10,000
7
-
0.64
<0.2
<0.2
90-300
<20
14-19
710-1,000
230-420
17-33
<5-46.3d
2-4
3,500-3,700
1.7
-
1.4
<0.2
<0.2
<30
<20
5
5
70
100
None
8
20,000
30
30
30
None
None
119
lOOf
-------
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 Human Health Risk

6.1.1 Contaminants of Concern

In order to focus the risk assessment on COCs, the groundwater guality data collected during the RI were
evaluated against analytical methods, guantitation limits, gualified and coded data, sample blank
contamination, natural background elements, essential nutrients, and risk-based concentrations in a
systematic manner according to guidance from both EPA and EPA Region 10.

The COCs and their concentration ranges for the groundwater sampled in the immediate vicinity of the TSF-05
Injection Well and the groundwater plume are listed in Table 5-1. The COCs list for the TAN groundwater
plume include TCE, PCE, cis- and trans-1,2-DCE, Sr-90, and H-3. The same COCs were identified for the TSF-05
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 contaminants exceed the 10-6 risk-based concentration for groundwater ingestion.
Tetrachloroethene was not detected above the detection limit of 500 jl/L in the TSF-05 Injection Well during
1992 sampling. However, it is considered a COG based on 1989 and 1993 data. The 1993 sampling showed PCE at
a concentration of 20-22 jlg/L in the TSF-05 Injection Well. Therefore, the final COG list includes TCE,
PCE, cis-1,2-DCE, trans-1,2-DCE, H-3, Sr-90, U-234, and Cs-137 (see Table 5-1). Any additional contaminants
detected during the OU 1-07B Remedial Action will be evaluated by the agencies for inclusion as COCs.

6.1.2 Exposure Assessment

The exposure assessment is used to estimate the type and magnitude of exposure to the COCs identified for the
TAN groundwater and the TSF-05 Injection Well. The exposure assessment involves identifying potentially
exposed populations and exposure pathways, estimating exposure concentrations (based on environmental
monitoring data and fate and transport modeling), and estimating the contaminant intakes for exposure
pathways. The result of the exposure assessment estimates 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 relinguish
control of the site.

Current access to the TAN groundwater is limited to production wells (TAN-1, TAN-2, ANP-8, FET-1, and FET-2),
which bring the groundwater to the surface 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 scenario 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 contaminant plume. Case 2 considered the TSF-05 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

Current land use

Industrial Workers
Future land use

Residential
Case 1
Residential
Case 2
Exposure scenario

Use of untreated groundwater from

production wells as potable water

Use of untreated groundwater from
production wells for showering
Use of groundwater from predicted
contaminant plume as potable water

Use of groundwater from predicted
contaminant plume for showering

Crops contaminated from irrigating
with predicted contaminant plume
groundwater

Use of groundwater TSF-05
Injection Well as potable water

Use of groundwater from TSF-05
Injection Well for showering

Crops contaminated from irrigating
with TSF-05 Injection Well
groundwater
Potential exposure
pathway
Ingestion of water
Inhalation of volatiles
Ingestion of water
Inhalation of volatiles
Consumption of crops
Ingestion of water
Inhalation of volatiles
Consumption of crops
-------
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 25-year period and to residents living in the study area over a
30-year period. Industrial and residential reasonable maximum 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 contaminants. Noncarcinogenic effects are characterized
by comparing projected intakes of substances to toxicity 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 guotient (HQ) of one, with an HQ of less than one indicating it is unlikely even for sensitive
subpopulations 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 (i.e., 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
10-6. A cancer risk level of 1 x 10-4 (1 in 10,000) means that one additional person out of ten thousand is
at risk of developing cancer if the site is not cleaned up.

The Integrated Risk Information System database and Health Effects Assessment Summary Tables provided the
toxicity values used in the risk assessment for the COCs.

The carcinogenic risks from the potential exposure pathways evaluated for the current industrial use of
groundwater from the TAN production wells are summarized in Table 6-2. The total carcinogenic risks from
ingesting TAN groundwater range from 6 x 10-7 to 8 x 10-7. The total carcinogenic risks from inhaling
volatiles while showering is 4 x 10-8. These results indicate the potential carcinogenic risk to the INEL
workers from water pumped from the TAN production wells is less than the acceptable risk range of 10-4 to
10-6. Table 6-2 also summarizes the chronic hazard index estimates for the potential exposure pathways
evaluated for the organic COCs for the current industrial use of groundwater from the TAN production wells.
The total hazard index for toxic effects from ingesting contaminated groundwater is 0.003. This value is
less than 1.0, indicating it is unlikely workers will experience adverse health effects. Therefore, both
carcinogenic and noncarcinogenic risk to industrial workers from TAN groundwater is minimal under the
current industrial use scenario.

A summary of the cancer risk estimates for exposure to organic contaminants and radionuclides under the
future residential use scenarios Case 1 and Case 2 are shown in Table 6-2. Total cancer risk estimates for
exposure under the future residential use scenario Case 1 are all within or below the target risks range of
10-4 to 10-6. Estimates of total cancer risk from the ingestion of contaminated groundwater under the future
residential use scenario Case 2 are greater than the acceptable target risk range. The noncarcinogenic HQs
for exposure under the future residential use scenarios Case 1 and Case 2 are shown in Table 6-2. The total
HQs for exposure under future residential use Case 1 are all less than one. In Case 2, exposure to TSF-05
Injection Well water, the HQs for organic contaminants are above one.
-------
Table 6-2. Summary of risk for Test Area North groundwater.

Scenario Carcinogenic Riska Hazard Indexb

Current industrial scenario (production wells)

Organic chemical water ingestion 8 in 10,000,000 0.003
(8 x 10-7)

Radioactive water ingestion 6 in 10,000,000 NAc
(6 x 10-7)

Inhalation of volatiles 4 in 100,000,000 NA
(4 x 10-8)

Total risk 1 in 1,000,000 0.003
(1 x 10-6)
Future residential exposure to groundwater plume (Case 1)

Organic chemical water ingestion 1 in 100,000 0.8
(1 x 10-5)

Radioactive water ingestion 4 in 1,000,000 NA
(4 x 10-6)

Inhalation of volatiles 7 in 10,000,000 NA
(7 x 10-7)

Organic chemical crop ingestion 3 in 1,000,000 0.1
(3 x 10-6)

Radioactive crop ingestion 1 in 100,000 NA
(1 x 10-5)

Total risk 3 in 100,000 0.9
(3 x 10-5)

Future residential exposure to TSF-05 groundwater (Case 2)

Organic chemical water ingestion 1 x 1,000 20.5
(1 x 10-3)

Radioactive water ingestion 5 in 10,000 NA
(5 x 10-4)

Inhalation of volatiles 5 in 100,000 NA
(5 x 10-5)

Organic chemical crop ingestion 2 in 10,000 2
(2 x 10-4)

Radioactive crop ingestion 5 in 10,000 NA
(5 x 10-)

Total risk 2 in 1,000 23
(2 x 10-3)

a. The NCP defines acceptable carcinogenic risk as <1 additional incidence of cancer in 10,000
to 1,000,000 or 10-4 to 10-6.

b. A hazard greater than 1.0 indicates that there may be concern for noncarcinogenic effects.

c. NA = not applicable.
-------
In summary, the risk characterization indicates there is concern for potential health risks to future
residents exposed to the contaminants found in groundwater pumped from the TSF-05 Injection Well and
immediate vicinity. The primary risk driver is the ingestion of groundwater contaminated with TCE.

6.1.4 Uncertainty

Standard EPA 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 aguifer physical
parameters. A constant source for the contaminants based on 1992 measurements in the TSF-05 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 25-year exposure to
constant concentrations of contaminated 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
contaminated water. The future resident exposure estimates are based on a 30-year exposure to contaminated
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 contaminants found in the TSF-05 Injection Well (Case 2) results in an
unacceptable risk according to the ranges listed in the NCP.

There are many uncertainties and unknowns 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 gualitative/semiguantitative
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-05 Injection Well as the sources of contamination, as identified in the human health assessment.
Ecological risk will be reevaluated during the WAG-1 comprehensive RI/FS (OU 1-10), and a more detailed
ecological risk assessment will be performed under the WAG 10 INEL Site-wide RI/FS.

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
contaminants, 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.
Contaminants can be absorbed into the body after being inhaled 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 contaminants 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 contaminants 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 contaminants 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 Assessment

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-25 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 the COCs have not been calculated using the new data. While the higher
contaminant concentrations could indicate risks to future receptors that are greater than previously
estimated 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-05
Injection Well. Therefore, the new information does not change the recommended remedial strategy for the OU
1-07B groundwater, which 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
reguire 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 remaining 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
transport 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 ft/day. The Interim
Action conducted under the 1-07A ROD confirmed that sludge could be removed from the TSF-05 Injection Well
but did not confirm the extent of sludge present 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 contaminants, 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 jlg/L TCE plume,
approximately 200 years would be reguired 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 jlg/L TCE contamination
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 jlg/L TCE
plume.
-------
7.1 Alternative 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 contain, treat in place, or extract and treat
any contaminated qroundwater within OU 1-07B. No institutional controls are assumed and the Interim Action
(OU 1-07A) would not be continued. Groundwater modelinq indicates that, with no action, the contaminant
plume for volatile orqanics would continue to spread and that the radioloqical plume would eventually shrink
as a result of decay. Groundwater monitorinq would be implemented under the No Action alternative to detect
chanqes in OU 1-07B that may lead to situations that would be considered immediately danqerous to the public
or environment. Any situation of this sort, detected throuqh monitorinq, would require mitiqative measures
to be taken to minimize risk to public health and the environment.

7.2 Alternative 2: Limited Action Consisting of Institutional Controls

Under this alternative, no action would be taken to remediate contaminated qroundwater and contaminant
sources associated with OU 1-07B. Instead, the Limited Action alternative would implement institutional
controls to protect current and future users from health risks associated with the qroundwater contamination.
Groundwater modelinq indicates that, with no action, the contaminant plume for VOCs would continue to spread
and that the radioloqical plume would eventually shrink as a result of decay. Specific actions or controls
could include qroundwater monitorinq, an alternative water supply, and/or access restrictions.

Groundwater monitorinq would be conducted annually to monitor the distribution, miqration, and fate of
contaminants already in TAN qroundwater. Groundwater monitorinq would use the existinq TAN qroundwater
monitorinq wells for OU 1-07B, and analyses of qroundwater samples would tarqet the COCs. An alternative
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 meetinq the water supply needs of future residents at TAN
after the institutional control period. Access restrictions would include land use notifications and
fencinq. Land use restrictions would include prohibitinq the placement of wells within the contaminated
plume and interferinq with remedial activities. Fencinq would enclose approximately 37 m2 (400 ft2) around
the immediate vicinity of the existinq TSF-05 Injection Well.

7.3 Alternative 3: 5,000 micrograms per liter Trichloroethene Groundwater Plume Extraction
Hotspot Containment and/or Removal with Aboveground Treatment

This alternative would involve (a) modification and operation of the existinq extraction system and GWTF, (b)
institutional controls and qroundwater monitorinq, (c) containment and/or removal with aboveqround treatment
of the hiqhly contaminated qroundwater and secondary source in the immediate vicinity of the TSF-05 Injection
Well (the feasibility of hotspot remediation will be determined in a series of surqe and stress tests), and
(d) extraction and treatment of qroundwater defined by the area of the aquifer with TCE concentrations
qreater than 5,000 ]lq/L.

This alternative would be performed in a phased approach. The existinq extraction system and treatment
facility would continue to be operated to support surqe 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 throuqh surqe and stress. The second phase
would include installation of wells for implementation of hotspot hydraulic containment. Surqe and stress
may continue to auqment hydraulic containment and will be evaluated for effectiveness prior to implementation
as a lonq-term remedy.

Hotspot containment would involve installinq one or more pumpinq wells to contain contaminants within the
5,000 jlq/L plume for extraction of qroundwater. Extracted qroundwater would be treated for VOCs aboveqround
and reinjected back into the aquifer within the capture zone of the extraction well(s). The process would
function as a hydraulically contained system, capturinq qroundwater, treatinq to remove the orqanic
contaminants, and then returninq the qroundwater back to the aquifer within the capture zone of the
extraction well(s). Effective containment of the secondary source and capture of the reinjected qroundwater
may reduce contaminant miqration beyond the capture zone. Hydraulic containment reduces further aquifer
deqradation, and ex situ VOC removal facilitates overall improvement of aquifer water quality.

Aboveqround orqanic compound removal would be accomplished by air strippinq, followed by carbon adsorption as
necessary to remove volatilized orqanic compounds from vapor off-qas qenerated durinq the strippinq process.
The off-qas treatment system will reduce emissions of volatilized orqanic compounds to acceptable atmospheric
levels in compliance with applicable or relevant and appropriate requirements (ARARs). Radionuclide
concentrations will be reduced by an ion exchanqe or equivalent process to the extent practicable as
determined by the aqencies. After treatment, process effluent containinq radionuclide (e.q., Sr-90, Cs-137)
concentrations above MCLs may be reinjected into the upqradient portion of the hotspot. Because there is no
treatment for tritium, process effluent containinq 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 the 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 30-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 jlg/L component of the plume during implementation of the 1-07B remedial action. Instead, the
site-wide RI/FS and subseguent ROD (OU 10-04) 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 jlg/L plume, contaminated groundwater would continue to flow downgradient at an estimated rate of
approximately 1 ft/day. Groundwater fate and transport modeling indicates aguifer dispersion would reguire
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-05.

7.4 Alternative 4: 25 micrograms liter Trichloroethene Groundwater Plume Extraction;
Hotspot Containment and/or Removal With Aboveground Treatment

Alternative 4 involves remediation of contaminated groundwater with TCE concentrations greater than 25 jlg/L,
as well as remediation of the secondary source at the TSF-05 Injection Well. Thus, Alternative 4 includes
remedial activity described under Alternative 3 with additional remediation of the groundwater plume defined
by the area of the aguifer that contains TCE concentrations over 25 jlg/L. Therefore, Alternative 4 would
reguire 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 simulations were performed in an effort to systematically determine the volume of TCE-contaminated
groundwater reguiring remediation. The simulation suggests that in order to achieve target MCLs or 10-4 to
10-6 risk-based concentrations for contaminants without established MCLs, the secondary source of
contamination around the TSF-05 Injection Well and groundwater contained in the greater than 25 jlg/L TCE
plume would reguire remediation. Following remediation of the greater than 25 jlg/L TCE plume, modeling
suggests that the less than 25 jlg/L TCE plume will naturally degrade to MCLs within approximately 100 years.
Revised groundwater modeling suggests that the treatment of the greater than 25 jlg/L 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 jlg/L 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 reguire 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 wells would be located so as to intercept contaminated groundwater with concentrations greater
than 25 jlg/L, which is currently estimated to extend 1.5 miles downgradient of the TSF-05 Injection Well.

Leaching from the secondary source would be reduced by containment and/or source removal, and contaminants
within the 25 to 5,000 jlg/L 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 liguid effluent resulting from dissolved phase plume
remediation would reguire treatment to remove Sr-90, Cs-137, or U-234 due to radioactive decay and adsorption
of these containments 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 reguired to operate the
hotspot containment and/or removal system is estimated to be the same
as that for Alternative 3.
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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 10-6 risk-based levels for contaminants without MCLs are achieved. Alternatives 3 and 4, combined with
the use of institutional controls for those portions of the plume not under active remediation, are
protective of human health and the environment.
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Table 8-1. Comparative Analysis of Alternatives.

Alternative #3: Alternative #4:
Alternative Evaluation Alternative #1: Alternative #2: 5,000 jlg/L 25 jlg/L
Criterion No Action Limited Action TCE Plume TCE Plume

Protection of human Noa Yes Yes Yes
health and the
environment

Compliance with NAb No2 Yesc Yes
ARARs

Long-term effectiveness + ++

Reduction of toxicity,
mobility, or volume
through treatment + ++

Short-term
effectiveness + ++

Implementability ++ +

Cost ++ +

State acceptance + ++

Community acceptance + +

a. Alternatives not meeting the threshold criteria were not evaluated further.

b. There is no ARAR analysis for the No Action alternative.

c. Assumes that additional remedial action will be taken in the INEL site-wide RI/FS.

+ Effectively meets criterion.

++ More effectively meets criterion.
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8.1.2 Compliance with Applicable or Relevant and Appropriate Requirements

A detailed list of ARARs pertinent to OU 1-07B 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 satisfy the 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 jlg/L TCE component of the plume for approximately 200
years. It cannot be assumed that institutional controls would be maintained for this length of time. The
reasonable timeframe for restoration of the aguifer to drinking water standards should not exceed 100 years,
which is in keeping with current land use assumptions for INEL. At the time of the Proposed Plan, it was
believed that Alternative 3 would meet the 100-year remedial action objective (RAO). However, recent
groundwater modeling has shown that after removal of the greater than 5,000 jlg/L plume, approximately 200
years would be reguired for natural dispersion to reduce the remaining plume to concentrations below
MCLs. Due to the 200 years reguired, Alternative 3 could only be implemented if further remediation of the
less than 5,000 jlg/L TCE part of the plume were included in the site-wide RI/FS. 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 jlg/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 Balancing Criteria

After evaluation of each alternative under the two threshold criteria, five balancing criteria are used to
evaluate other aspects of the potential remedial 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 Long-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 aguifer to
below MCLs within 100 years, this alternative will be effective at preventing exposure to unacceptable 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 Reduction of Toxicitv, 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 contaminants. 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.
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Table 8-2. Estimated costs associated with remediation alternatives (present worth).

Alternative

Cost element 12 34

Construction 0 128,000 707,000 3,279,000

Operationsa 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

Monitoringc 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

Totald 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 studies will be required for the contaminant recovery technologies being considered
for remediation of the TSF-05 Injection Well hotspot and the 25 to 5,000 jlg/L 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 100-year institutional control period.
Monitoring costs for Alternatives 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 estimating 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 contaminated groundwater in the greater than 25 jlg/L dissolved phase plume.

8.2.4 Implementabilitv

Alternatives 3 and 4 require a phased approach to verify treatment performance and determine sizing criteria
for the remedial design.

Alternative 4 would require a greater number of wells, additional treatment capacity, and disposal of a
larger volume of residual waste, thus Alternative 4 has more technical administrative difficulties than
Alternative 3.

8.2.5 Cost

A summary 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 jlg/L TCE component of the
plume would not be addressed until the site-wide RI/FS is written. During implementation of the 1-07B
remedial action specified under Alternative 3, no action other than institutional controls and monitoring
would be taken on the less than 5,000 jlg/L component of the plume. Instead, the site-wide RI/FS and
subsequent ROD (OU 10-04) would include necessary remedial actions for that portion of the plume outside of
the hydraulic containment area.
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Table 8-3. Cost summary for the OU 1-07B selected alternative.
Activity

Phase A
Construction
($)
Remedial Design (RD)/ NA
Remedial Action Scope and
ROD revisions

Phase B

Continuing operations of 707,000
GWTF

Treatability studies/support NA
activities
Operations
and
($)
NA
2,037,000

283,000

694,000

991,000
Bench-scale testing NA

Pilot-scale testing 785,000

Phase C

Final remediation
technology

Implementation and 2,572,000 5,498,000
operation

Monitoring

Monitoring 1,971,000

Total present value cost 4,064,000 11,474,000
Waste
handling and
maintenance disposal
($)
NA
NA

56,000
616,000
Indirects Contingencya Subtotal
($)
($)
450,000 50,000
NA

NA
NA

NA
1,323,000 8,034,000 4,993,000
($)
500,000
651,000 1,876,000 1,054,000 6,325,000
1,588,000 929,000 2,800,000
694,000

1,832,000
4,120,000 2,960,000 15,766,000
1,971,000

29,888,000
a. Agency notification will be reguired prior to allocation of contingency, should funds in excess of 90% of the amounts
specified for construction, operations, waste handling, or indirects be reguired to complete the activity.
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The estimated $25,800,000 cost for Alternative 3 given in the Proposed Plan is for a treatment 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 100 gpm over a
30-year O&M period with an estimated cost of $23,657,000.

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 administrative 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 RI/FS. 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. SEIiECTED REMEDY

9.1 Major Components of the Selected Remedy

After reviewing recent information provided by groundwater capture and treatment simulations and subseguently
evaluating Alternatives 1 through 4 against the nine specific CERCLA criteria, the selected remedial action
for OU 1-07B 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, reguires a commitment to perform necessary remedial actions on the less than 5,000 jlg/L plume
in a subseguent RI/FS. 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
containment and/or removal of the hotspot with subseguent treatment of the 25 to 5,000 jlg/L component of the
plume, would greatly reduce the extent of aguifer contamination 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 m 1996 and serves as a
transition from 1-07A to 1-07B 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 alternative. 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 seguence 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 determined that the preferred alternative will be protective of human
health and the environment, will comply with applicable Federal and State regulations, and will be cost
effective.

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9.1.1 Need for Treatabilitv 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 contamination in situ or reducing the toxicity of
contaminants aboveground.

The selected remedy of groundwater pumping, aboveground treatment (air stripping and off-gas treatment, or
eguivalent technology as necessary) and reinjection of treated groundwater should be effective in restoring
much, if not all, of the aguifer to drinking water guality 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 most promising
new and innovative 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 1-07A Interim Action to 1-07B Final Remedial Action

Phase B))Hotspot Containment and/or Removal with Treatability Studies

Phase C))Dissolved Phase Groundwater Treatment 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))Transition of OU 1-07A Interim Action to OU 1-07B Final Remedial Action. The OU 1-07A
surge and stress pumping of the TSF-05 Injection Well will continue. This action will be done to remove
secondary source material, pump and treat contaminated groundwater in the vicinity of TSF-05, and collect
data on aguifer parameters to establish the potential for continued pumping of the hotspot for removal of the
secondary source of TCE contamination. The transition may include installation of wells to support remedial
activities. Phase A is directly associated with the OU 1-07A ROD, which will end with the signing of the OU
1-07B ROD. However, the OU 1-07A 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 contaminants 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-05 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 5,000 jlg/L TCE
contaminated plume. Treated water will be reinjected within the extraction well capture zone, thus creating
a hydraulically system of extraction, treatment, and reinjection. Hydraulic containment will enhance removal
of contaminants 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 aguifer and may contain contaminants that exceed MCLs.

On the basis of current data, surging and stressing TFE-05 Injection Well will result in high organic and
radionuclide influent concentrations. The extraction/treatment system will be operated and/or modified to
reduce effluent concentrations of volatile organic contaminants 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 eguivalent 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 "a") 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 fl")") Hotspot Containment and/or Removal and Treatability Studies. Hotspot containment and/or
removal will involve implementing groundwater extraction in the hotspot area at a rate sufficient to create
hydraulic containment of TCE and other contaminants within the greater than 5,000 jlg/L plume. Surge and
stress will continue during Phase B. Surge and stress data will be evaluated to determine whether the
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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 considered an enhancement of the OU 1-07A Interim Action. Additional wells may be installed,
as necessary, and will be operated within the greater than 5,000 jlg/L TCE plume at a rate sufficient to
create hydraulic containment and prevent contaminant migration. Preliminary 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 (IDAPA) emission rate screening levels, air
concentration screening levels, and calculated emission rate limits for OU 1-07B.

IDAPA emission rate Air concentration Calculated emission
Contaminants screening level screening level increments rate limit
of concern (lb/hr)a,b (]lg/m3) (Ib/hr)

TCE 0.00051 0.077c 0.185

PCE 0.013 2.1c 5.05

DCE 52.7 39,500d 1,254

a. Emission screening levels for TCE, PCE, total 1,2,DCE are derived from IDAPA 16.01.01.585 and
16.01.01.586))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 Ib/hr reguirement of IDAPA
16.01.05.008 (40 CFR 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 1-07A.
The system will consist of a multimedia filter and/or separator for nonagueous phase liguids and suspended
solids and an air stripper with air pollution controls as necessary (e.g., activated carbon or eguivalent
off-gas treatment technology). The air stripper will be operated in compliance with State and Federal air
and hazardous waste management reguirements. 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 aguifer within the hydraulic containment zone to enhance flushing of contaminants within the
hotspot. Although contaminant concentrations in reinjected groundwater may exceed drinking water standards,
the selected remedy employs an extraction, treatment, and reinjection process that substantially improves
aguifer water guality. Furthermore, institutional controls will ensure that contamination will not endanger
present or future beneficial use.

Storage of hazardous or mixed waste generated from groundwater treatment constitutes permissible storage for
the purpose of accumulating sufficient guantities 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, subseguent management will comply with EPA's "Off-Site Rule" (40 CFR
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 knowledge/history will be performed on all treatment plant waste residuals to determine compliance
with State and Federal hazardous waste management reguirements. Periodic monitoring of the treatment system
influent contaminated groundwater for selected organic COCs, and effluent air and water from the air stripper
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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 a
new and innovative 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 remediating 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, Technical Memorandum for Waste Area Group 1, Operable Unit 1-07B,
Alternatives Evaluation (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 jlg/1 portion of the plume

• Reductive iron dechlorination

• In 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 Report is 36 months from
the signing 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
contaminants 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 contaminants 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 microoganisms.

The benefit of in situ bioremediation is that VOCs are treated in the aguifer, thereby lessening or
eliminating 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
reguired to determine 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 estimated 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
recommended 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 contamination
using extraction wells to draw contaminated groundwater through these reactive zones. The treatability study
will evaluate the most effective design of an in situ bioremediation system for both the hotspot and the 25
to 5,000 jlg/L portion of the plume.

Reductive 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 agueous 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.
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Additionally, studies indicate that while degradation products are created by this process, they are also
destroyed given adeguate 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 filings. 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 PCE 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 aguifer and the oxidation reaction occurs in situ. Therefore
the complexity of the reguired 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 remaining solvent, augmented with more oxidant if needed, and then
reinjected into the source area. A bench-scale study to evaluate this technology under site conditions would
be conducted followed by a pilot field-scale demonstration to optimize remedial design.

Natural Attenuation))The effect of natural contaminant degradation processes may augment simple aguifer
dispersion during natural attenuation of groundwater contaminants. However, site-specific information is
lacking on the potential for biotic degradation, abiotic degradation or other natural attenuation processes
that may affect the TCE contaminated 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 processes. The results of this study will be
used to refine fate and transport simulation estimates of aguifer restoration timeframe and to assist in
design of Phase C remedial action.

Monolithic Confinement))The use of grout as a physical barrier to groundwater flow is a well established
process. The determination of necessary well spacing and grout guantity will be evaluated under the
Treatability Study. If the above treatability studies do not show promise, and the estimated timeframe for
continued pumping and aboveground treatment appears indefinite, cost-effectiveness of this option versus
long-term pumping and aboveground treatment will be evaluated.

9.1.2.3 Phase C))Dissolved Phase Groundwater Treatment with Continuation of Hotspot Containment and/or
Removal. Dissolved phase groundwater treatment will involve the design of extraction wells, treatment
systems, and reinjection wells approximately 3 years after signature of this ROD. Phase C remedial activity
will be designed to capture the 25 to 5,000 jlg/L portion of the plume, treat via air stripping, and reinject
treated groundwater to enhance natural attenuation in the less than 25 jlg/L plume. Hydraulic containment
and/or 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 jlg/L TCE contaminated plume. Specific pumping
rates, well depths, number of wells and well locations 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 minimal 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 eguipment as a contingency. Periodic monitoring of the treatment system influent contaminated
groundwater for selected organic and inorganic COCs, and of effluent air and 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.
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9.1.2.4 Institutional Controls and Groundwater Monitoring))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 10-4 to 10-6 risk-based concentrations for contaminants without MCLs. Administrative
controls shall include placing written notification of this remedial action in the facility land use master
plan; the notification shall prohibit (1) installation of any wells accessing the aguifer within the 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 reguest that a similar
notification be placed in the BLM's property management records for this site. U.S. Department of Energy
shall provide EPA 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 10-4 to 10-6
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 jlg/L TCE plume,
document COG concentration charges over time, provide information on the attenuation rate of the plume, to
evaluate attainment 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 Replace Conventional Pump and Treat

In the event that 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 freguent 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 jlg/L is effectively being contained, based on sampling results.

• Determine whether the greater than 25 jlg/L portion of groundwater TCE plume is attenuating as
modeled if containment is effective.

• Determine whether the groundwater restoration assumptions are still valid. These are, but
are not limited to the assumptions 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 DCE maintains ownership of the property. It is estimated that
institutional controls will need to be maintained and monitored for 100 years.

• Evaluate and use groundwater guality 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 1-07B remedial action. Similar evaluations will be performed for subseguent
5-year reviews. Other factors that will be taken into considered during the reviews include, but are not
limited to

• Acceptability of the residual risk levels achieved

• Cost of continuing the action in comparison to incremental risk reduction expected
• Changes in future land use or changes in the EPA groundwater protection strategy
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• Technical practicability of restoring the aquifer (e.g., ability to contain the portion of the
plume leaving TCE concentrations greater than 5,000 jlg/L, modifications that could expedite
the cleanup in a cost effective manner).

9.2 Remedial Action Objectives

As part of the RI/FS process, RAOs were developed in accordance with the NCP and EPA guidance for conducting
RI/FS 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 domain 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 contaminants for which an MCL does not
exist, the contaminant concentration will be such that the total excess cancer risk posed by
release of contaminated groundwater will be within the acceptable range of 10-4 to 10-6. 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 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 aguifer 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 10-4 to 10-6. Volatile organic compounds
discharged to the atmosphere from GWTF operations will not exceed the calculated emission rate
limits specified in Table 9-1.

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.

10.1 Protection of Human Health and the Environment

10.1.1 Protection of Human 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 quality within 100 years.
Removing contaminants will prevent further degradation of groundwater and will be protective of future use.
Treated water will be reinjected into the aquifer and will meet appropriate performance standards as
determined during design. Any short-term threats associated with the selected remedy will be addressed by
engineering controls and standards health and safety practices.
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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
rodent 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-90 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 contaminants in water that might be used for irrigation in that scenario.
Short-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 minimize adverse environmental effects that could occur as a result of future 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 ARARs for the selected alternative is shown in Table 10-1. A general
description of the ARARs is summarized below in Section 10.2.1. a

10.2.1 Chemical-Specific ARARs

• State of Idaho Toxic Air Pollutants, Noncarcinogenic and Carcinogenic Increments (IDAPA
16.01.01.585 and .01.586). These requirements involve demonstration of preconstruction
compliance with Toxic Air Pollutants emission screening levels. If the emissions exceed the
screening levels, then model results must show compliance with the acceptable air concentration
limits for carcinogens (AACC) at the INEL boundary (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 control
technology must be applied at the source.

a. Citation of the Idaho Waste Management Regulations incorporate by reference the federal
hazardous waste regulations.

• National Emission Standards for Hazardous Air Pollutants (40 CFR 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 mrem/yr.

• 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), and Section
3020 of RCRA. The UIC 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 the substantive
intent of the UIC and RCRA regulations.

State of Idaho Drinking Water Standards (IDAPA 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.
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Table 10-1. Summary of ARARs for Alternative 4.
Requirements

CAA and Idaho Air Regulations

Idaho Air Pollutants noncarcinogens

Idaho Air Pollutants carcinogens

NESHAPs - < 10 mrem/yr

NESHAPs - monitoring

ID Fugitive Dust

RCRA and HWMA

Generator Standards

Hazardous Waste Determination

General Facility Standards

General Waste Analysis

Location Standards

Preparedness and Prevention

Closure Performance Standard

Disposal/Decontamination

Use/Management of Containers

Tank Systems

Miscellaneous Units

Air Emission Standards for Process Vents

Land Disposal Restrictions

RCRA
Citation
Action
ARAR type
Chemical Location
IDAPA 16.01.01.585

IDAPA 16.01.01.586

40 CFR 61.92

40 CFR 61.93

IDAPA 16.01.01.650 and .651

IDAPA 16.01.05.006

40 CFR 262.11

IDAPA 16.01.05.008

40 CFR 264.13

40 CFR 264.18 (a) and (b)

40 CFR 264.31-.37

40 CFR 264.111

40 CFR 264.114

40 CFR 264 Subpart I

40 CFR 264 Subpart J

40 CFR 264 Subpart X

40 CFR 264 Subpart AA

IDAPA 16.01.05.011

Section 3020
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UIC
Idaho Results for the Construction and Use
of Injection Wells

ID Public Drinking Water

MCLs (numerical standards only)

Secondary MCLs (numerical standards only)

National Historic Preservation Act

Assessing information needs

Locating Historic Properties

TBCs

Radiation Protection of the Public and the Environment

Fire Protection

Radioactive Waste Management
IDAPA 37.03.03

IDAPA 16.01.08.050.02 and .05

IDAPA 16.01.08.400.03

36 CFR 800. 4 (a) (1) (i) , (iii) (a) (2)

36 CFR 800.4(b)

DOE Order 5400.5

DOE Order 5480.7A

DOE Order 5820.2A
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10.2.2 Action-Specific ARARs
National Emission Standards for Hazardous Air Pollutants emission monitoring and test
procedures (40 CFR 61.93). An operator of a source with radioactive (tritium) emissions
under 0.1 mrem/yr is required to perform periodic confirmatory measurements to confirm low
emissions.

State of Idaho Rules for Control of Fugitive Dust (IDAPA 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 CFR
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 CFR 264.13) contains
substantive requirements for analysis of hazardous waste.

State of Idaho Standards for Owners and Operators of Hazardous Waste Treatment, Storage, and
Disposal Facilities, IDAPA 16.01.05.008, Preparedness and Prevention (40 CFR 264.31-.37)
contains substantive standards which apply to the design, operation, and maintenance 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, Closure Performance (40 CFR 264.111) and Disposal or
Decontamination (40 CFR 264.114) contain 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 contaminated 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 J) 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 Ib/hr 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 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.
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• 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 reguirements for Class V injection wells.

10.2.3 Location-Specific ARARs

National Historic Preservation Act [36 CFR 800.4(a)(1)(i), (iii)(a)(2), and .4(b)] reguires
assessing information needs and locating historic properties, and applies when locating
treatment systems outside the TAN facility fence.

• 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 CFR 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

• To-be-considered, action-specific material is contained in DOE Orders 5400.5, "Radiation
Protection of the Public and the Environment, " 5480.7A, "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 Permanent Solutions and Alternative Treatment or Resource Recovery Technologies to 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 treatment; 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
containing and treating the source and by extracting and treating the dissolved phase plume.

10.5 Preference for Treatment as a Principal Element

By treating the contaminated 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 treatment 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 jlg/L) can be remediated 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 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 summarizes information on the group of no action sites at TAN agencies
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identified by the DOE, EPA, and IDHW as posing 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 contaminant
concentrations can be readily identified. 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 guantities of residual
contamination. These sites are termed low probability hazardous sites. For typical low probability
hazardous sites, either the location and guantities of hazardous substances disposed of or leaked are unknown
or there is significant uncertainty in the actual conditions.

In accordance with the FFA/CO, the agencies have 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 guestions, forms, tables, and a gualitative 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 reguired.
This evaluation process was then used to determine whether (a) the site poses a clear risk that reguires 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 reguires no action.

Over 40 sites at TAN fall into the category of low probability hazardous sites. Of these, the 30 sites
discussed in 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 contamination sites, and
wastewater disposal sites. The evaluation of all of these sites has 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 noted, 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 unrestricted use. In many cases, the tank and
the associated piping have been recycled as scrap metal.

Several of the tank sites had petroleum-related organic contamination (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 contaminants did not exceed the 10-6 (1 in 1,000,000) risk-based
concentrations for the air volatilization, soil inhalation, soil ingestion, or groundwater ingestion exposure
routes.

OU 1-02, IET-01 [Underground Storage Tank (TAN-318)]. IET-01 is a former 5,000-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-05 [Underground Storage Tank (TAN-1714)]. IET-05 is a former 550-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 contaminants. No contaminants were detected
at levels that exceed the 10-6 risk-based concentrations. The storage tank and its associated piping were
removed 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 550-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.
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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 he tank removal and the results of soil analyses from the excavation
detected no organic or inorganic contamination.

OU 1-02, IET-10 [Diesel Fuel Underground Storage Tank (TAN-1712)]. IET-10 is a former 30,000-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
reguired at the site to pose an unacceptable risk. The risk evaluation estimated that xylene concentrations
in the soil would need to be 6,400 ppm to exceed an HQ of 1 for the soil ingestion, air volatization, air
inhalation, or groundwater ingestion exposure routes.

OU 1-02, IET-10 [Heating Oil Underground Storage Tank (TAN-1713)]. IET-11 is a former 20,000 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 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 reguired 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, LOFT-05 [Fuel Tanks (TAN-767 A and B)]. LOFT-05 is the site of two 35,000-gallon 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, LOFT-06 [Tank east of TAN-631 (TAN-765)]. LOFT 06 is a former 2,000-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-contaminated 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
contamination 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, LOFT-08 [Underground Storage Tank (TAN-764)]. LOFT-08 is a former 15,000-gallon tank installed in
1958 and last used in 1963. Records indicate the tank was intended for storage of potentially radioactively
contaminated 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 LOFT-08 tank and
the associated piping were removed.

No holes were observed in the tank, and field screening detected no organic contamination 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 reguired 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 volatilization, air inhalation, or groundwater
ingestion exposure routes.

OU 1-01, TSF-01 [Underground Storage Tank (TAN-1702)]. TSF-01 is a former 3,000-gallon diesel fuel tank
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installed in 1953 and last used in 1985. A pipe leak in 1983 reportedly released 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 reguired 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-620 (TAN-1221)]. TSF-13 is a former 550-gallon
gasoline tank. Records indicate the tank was installed in the early 1950s to supply a fire-pump engine. The
tank and its contents were removed about 1980.

No releases have ever been recorded and none are known 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-gallon 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 reguired at the site to pose an unacceptable risk. The risk
evaluation estimated that benzene concentrations in the soil would need to exceed 197 ppm to pose a 1 x 10-6
excess cancer risk to soil ingestion, air inhalation, air volatilization, 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
volatilization, air inhalation, or groundwater ingestion exposure routes.

OU 1-02, TSF-15 [Underground Storage Tank (TAN-779)]. TSF-15 is a former 3,000-gallon fuel oil tank that
contained 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 contaminants 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 1995 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 1950s. The
tank and associated piping are believed to have been removed sometime between the late 1950s 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 10,000-gallon diesel fuel tank.
Records indicate the tank was installed in 1959 and last used in 1960 when the AMP project was terminated.
The tank, its contents, and the associated piping were removed in August 1990.
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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-10 [Underground Storage Tank (TAN-644)]. WRRTF-10 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.

OU 1-02, WRRTF-12 [Diesel Fuel Underground Storage Tank (TAN-1706)]. WRRTF-12 is a former 1,000 gallon
diesel fuel tank used to supply an emergency generator. Records indicate the tank was installed in the late
1950s and last used in 1975. The tank, its contents, the associated piping, and some contaminated soil
around the tank were removed in August 1990.

No holes were observed in the tank, and field screening detected some organic contamination 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.

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 initial
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 contamination or determined that contaminant concentrations
remaining at the specific site(s) are at levels that pose an acceptable risk to human health or the
environment.

OU 1-06, LOFT-01 [Diesel Fuel Spills (TAN-629)]. Loft-01 is the site of several diesel spills that occurred
when a diesel tank overflowed during filling between 1982 and 1986. The fuel oil flowed into 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). LOFT-03 was used on an irregular basis for
surface disposal of construction debris such as concrete, metal, and wood from the late 1960s to the early
1970s. Most 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
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any organic or radiological contamination.

OU 1-06, LOFT-10 [Sulfuric Acid Spill (TAN-771)]. LOFT-10 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
guickly neutralized 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 10-gallons of pure sulfuric acid. Except for the sulfuric
acid spill, no other hazardous or radioactive materials are known or suspected to have been disposed of at
LOFT-10.

OU 1-01, LOFT-11 (Cryogen Pits). LOFT-11 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 LOFT-11.
The site is currently covered by the concrete floor of Building TAN-629.

OU 1-01, LOFT-14 (Asbestos Pipe). LOFT-14 was an abandoned metal pipe covered with asbestos insulation lying
exposed on the ground. In July 1991, all the asbestos 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 insulation, no other hazardous or radioactive materials are known or suspected to be
present at the LOFT-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-15 (LOFT Buried Asbestos Pit). LOFT-15 is the former site of a construction materials burn 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-15. 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 1950s to the mid 1970s. According to personnel
interviews, the only hazardous material or waste disposed of in this area was one 55-gallon drum of sulfuric
acid sometime between 1958 and 1959.

Although sampling was not conducted at TSF-04, a 1990 field 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 calculated that only 0.49 m3 (0.65 yd3) of TAN soil would be
required to neutralize 10 gallons of pure sulfuric acid. Any residual contaminants would have likely been
removed by subsequent gravel quarrying activities. Except for the one drum of sulfuric acid, no other
hazardous or radioactive materials are known or suspected to have been disposed of at TSF-04.

OU 1-02, TSF-25 [Underground Drain Sump East of TAN-609 (TAN-1737)]. TSF-25 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 AMP project only to collect waste
jet fuel from 1955 to 1961. Later use of the building did not require the use of the sump. Therefore,
except for jet fuel, no other hazardous or radioactive materials are known or suspected to have been disposed
of at TSF-25. 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
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inspections and field screening of the debris did not reveal the presence of any organic or radioactive
contamination.

12.3 Waste Disposal Sites

The following three low probability hazardous sites are classified as wastewater disposal sites because 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 contaminants 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
wastewater potentially containing demineralization or corrosion-inhibiting solutions.

No hazardous or radioactive contaminants are known to have been discharged to the pond. Review of engineering
drawings indicates a checkvalve in the steam system would prevent any potential contaminants 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-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 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-05 sampling results.
The results from two rounds of groundwater monitoring samples collected in 1994 from the former WRRTF-05
Injection Well detected only Co-60 at concentrations greater than acceptable risk levels. The presence of
Co-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-03 (Evaporation Pond). WRRTF-03 is an unlined evaporation pond used to dispose of process
water and cooling water from 1983 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 indicate 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
wastes 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 Co-60 at concentrations greater than acceptable risk levels. The presence of
Co-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 native soils or biodegraded.
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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 into use. Therefore, although the WRRTF-06 pond was not sampled, some gualitative
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 Co-60 at concentrations greater than acceptable risk levels. The presence of
Co-60 in the WRRTF-05 Injection Well is from a one-time release in the mid-1960s and not result of routine
disposal activities at the WRRTF.

12.4 Decision Summary 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-1 evaluations, it was determined
that no significant sources of contamination exist at these sites. Conseguently, it was decided that these
sites pose no unacceptable risks to receptors, and therefore no remedial actions are necessary.

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 Changes

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 EPA 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 RI/FS to evaluate the site conditions and make appropriate remedial
recommendations.
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APPENDIX A

Responsiveness Summary

OVERVIEW

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 (INEL). As described in the Record of Decision (ROD), the unit
comprises the Technical Support Facility (TSF) Injection Well (TSF-05) 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 a 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 treatment
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 jlg/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 contaminants 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 Summary recaps and responds to significant comments received during the public comment
period for this ROD. Generally, the comments received reflected 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 pumped
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.

Background on Community Involvement

To initiate the TAN Groundwater Contamination 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 guestions, 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 reguest for
extension of the public comment period was received and granted, extending 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 Availability for
the Proposed Plan was published January 5, 1992, in eight major Idaho newspapers: the Post Register in Idaho
Falls, the Idaho State Journal 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 to 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
guestions, 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
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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 Contamination
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 RI/FS 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 Idaho State Journal (Pocatello), the South Idaho Press (Burley), the Times News (Twin Falls), the
Idaho Statesman (Boise), the Lewiston Morning Tribune (Lewiston), the Idaho 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 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 reguests 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
(EPA) , 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 guestions 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 guestions, and
receive public comments. Members of DOE-ID and IDHW were present at the 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 meetings 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
guestion and answer periods, followed by formal comment periods. The entirety of each public meeting was
recorded by a court reporter; transcripts 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 subseguent 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 comments 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 Radioactive Waste Management Complex
(RWMC), selected in accordance with the 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). The decision for this OU is based on information contained in the Administrative Record.

Summary of Comments Received and Agency Responses

Comments and guestions raised during the public comment period on the TAN Groundwater and No Action Sites
Proposed Plan are summarized below. Several guestions were answered during the informal guestion-and-answer
period during the public meetings on the Proposed Plan. This Responsiveness Summary does not attempt to
summarize or respond to the issues and concerns raised during that part of the public meeting. Complete
transcripts of the meetings, including the agencies' responses to these informal guestions are contained in
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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, however, are beyond 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 Proposed Plan, guestions 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 information 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 guestions 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 guestions 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 1-07B)

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. (T3-1, 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 (FFA/CO).

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 aguifer both in the
dissolved phase plume and at the hotspot. In the plume, volatile organic compounds (VOCs) dissolved in
groundwater will be treated to less than maximum contaminant levels (MCLs) or 10-4 to 10-6 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 containment. Contaminated 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 minimum, 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 treatment technologies:
bioremediation and chemical oxidation. If treatability testing of either of these technologies progresses to
field scale, substances will be injected to the aguifer 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 enhance growth of microorganisms that are responsible
for degrading VOCs. In situ bioremediation may also involve addition of microorganisms to the aguifer 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 are implemented, effects to the aguifer 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 (extraction/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 population. The treatment facility will be constructed within the TSF in an area that has had
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historically high levels of activity (i.e., 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 implementation of Alternative 4 will include
disturbances to soils associated with well installation and the layout of eguipment supporting the enhanced
extraction technologies and groundwater treatment systems. The eguipment 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 endangered animal species or species 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 contaminants of concern introduced into the food web. This
ecological risk assessment is based on conservative and general assumptions, and only one exposure route
(ingestion) for one receptor (rodent). The calculated risk from organic contaminants 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. Implementing Alternative 4 will not create exposure to
radionuclides for ecological receptors because evaporation ponds will not be used. The guantitative
ecological risk assessment for the WAG 1 Comprehensive RI/FS will more fully address ecological receptors.

General Comments on the Proposed Alternatives

4. Comment: One commentor asked, "What if the remedial action objective (RAO) changed during Phase 1?"
Further, he asked, "After Phase 1, what if you find that progress towards achieving the RAO is minimal?"
(Wl-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 contamination 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 (formerly 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 TSF-05). 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." (Wl-4)

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 estimated in the Proposed Plan are overly
conservative, thereby excessively inflating the costs of remediation. On the basis of reduced pumping rates
now considered adeguate 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 contaminant concentrations drop below MCLs or risk-based levels. Any new
information generated by the remedial action will be evaluated during these periodic reviews.

6. Comment: One commentor simply stated that the groundwater should be cleaned up as guickly as possible.
(W5-1)
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Response: The agencies agree with the commentor. The National Contingency Plan which is the implementing
regulation for CERCLA reguires 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
reguires 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 aguifer restoration to drinking water standards should not
exceed 100 years. The 100-year timeframe is consistent with current INEL land use assumptions. The
estimated time frame reguired 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 contaminants and aguifer system. The actual length of time necessary to remediate the
hotspot and the 25-y.g/L groundwater plume is largely dependent upon the success of each phase.

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 1-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)

Response: The scenario envisioned 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
contamination. Grouting may have value in the context of another alternative to inhibit contaminant
migration. The agencies agree that treatment or containment is necessary to return the aguifer to beneficial
use within 100 years and alternatives that do not provide for treatment or containment of groundwater are
unacceptable.

8. Comment: One commentor stated that due to decreased replenishment (drought) and increased use
(irrigation, etc.), the water table has dropped. (W9-3)

Response: In 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 commentor stated,
this decline in the top level of the aguifer is largely due to decreased replenishment and increased
consumptive use.

9. Comment: One commentor expressed support of the concept of reinjection of treated groundwater due to
the nonconsumptive use. (Wll-4)

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 adeguately described the extent or the degree of contamination in the aguifer. He
asserted that because the agencies are seeing things that are surprising them, this is an indication that
they lack some understanding as to the degree of contamination in the aguifer. The commentor also suggested
that the agencies lack an adeguate understanding of how the aguifer 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 contamination in the aguifer. The Snake River Plan Aguifer 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 contamination 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.

11. Comment: One commentor asserted that the compounds existing in the aguifer 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
inadeguate records exist to determine the past use of the halogenated organics found in the contaminated
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
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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 W13-5)

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 of 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 aguifer 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 guite 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.

12. Comment: 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 W13-8)

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 different 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 documented in the May 1992 Remedial Investigation/Feasibility Study Work
Plan for OU 1-07B. However, 60 drums of sludge and liguid were removed.

13. Comment: One commentor stated that when the well's pump and piping were removed after the sludge
removal activity was abandoned, external contamination (on the outside of the pump and piping) was flushed
back down the well during steam cleaning operations. The commentor argued that contaminated liguid, 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 contamination from the well.
(W13-9 through W13-12)

Response: The comment 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-05) is to
remove residual contamination from the injection well. Part of the purpose of the selected alternative is to
contain and treat the portion of the aguifer contaminated with TCE concentrations above 5,000 jlg/L. These
actions include treatment of the contaminated groundwater with a more thorough design than the 1990 removal
effort.

14. Comment: One commentor favored Alternative 2 (Limited Action Consisting of Institutional Controls).
(W2-1) He argued that the movement of water in the aguifer has been so slight that the contamination would
not pose a threat to anyone unless they drilled into the area. "Drilling such a well," he stated, "is highly
unlikely since the property should be retained for its present purpose for a number of years into the
future." (W2-2, W2-3)

Response: 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 remediated, contaminant levels
in the vicinity of the TSF injection well would still exceed drinking water standards even at this later
date. In fact, the results of the RI indicated that without remediation, the well would continue to pollute
the Snake River Plain Aguifer for hundreds of years into the future.

15. Comment: A commentor asked "If land-use is considered, is the additional cost of Alternative 3
justified over Alternative 2?" (W10-1)

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. As 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
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conducted in accordance with the Groundwater Protection Strategy presented in the National Contingency Plan.
This regulation reguires 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 aguifer 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 contaminant plume would continue to grow and
contaminant concentrations would exceed drinking water standards for hundreds of years. Conseguently,
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.

Alternative 3 involves removal or containment of the greater than 5,000 jlg/L 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 y.g/L portion of the plume, approximately 200 years would be reguired for dispersion to
reduce the remaining plume to concentrations below MCLs. Therefore, Alternative 3 would only meet the
100-year restoration timeframe if further remediation of the less than 5,000 jlg/L 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 dependant on subseguent remedial actions. In addition, Alternative 4 is more effective
in reducing the 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 uncontaminated groundwater. With respect to remedial action costs,
the operations and maintenance costs to implement Alternative 4 would be greater than Alternative 3, but the
restoration timefame would be accelerated. Therefore, the agencies agree that Alternative 4 better satisfies
the CERCLA evaluation criteria than does Alternative 3.

16. Comment: A commentor gueried, "Considering the flow rate of the aguifer, has the concentration of
contaminants at a point where unrestricted access will be possible (likely) in the future been calculated to
justify the cost of Alternative 3?" (W10-2)

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.

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 institutional controls to prevent use of contaminated groundwater until cleanup
standards are achieved by plume dispersion and radioactive decay. However, Alternative 2 would reguire an
unacceptable time period, i.e., 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, conseguently Alternative 2 was not
selected.

Alternative 3 involves removal or containment of the greater than 5,000 jlg/L 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 jlg/L portion of the plume; approximately 200 years would be reguired for dispersion to
reduce the remaining plume to concentrations below MCLs. Conseguently, Alternative 3 would only meet the
100-year timeframe for aguifer restoration if additional remediation of the less than 5,000 jlg/L 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 subseguent 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 contaminants than Alternative 3, 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, the restoration time would be accelerated. Therefore, the
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agencies agree that Alternative 4 better satisfies the CERCLA evaluation criteria than does Alternative 3.

17. Comment: One commentor asked about the selected alternative, "How many injection wells would be
reguired and where would they be sited so as to not influence the pump/treat operation and dilute existing
groundwater contamination?" (Wll-3)

Response: The specific number and location of reinjection and extraction wells will be determined as part of
the RD process. The locations of the reinjection and extraction wells will be selected such that the well
system will provide hydraulic containment and enhance groundwater extraction and cleanup as applicable. The
well system will be designed to provide remediation of the entire TCE contaminant plume where TCE
concentrations are greater than 25 jlg/L. The remediation strategy will promote aguifer restoration by
collected reinjection of treated groundwater into the aguifer and simultaneous extraction and treatment of
contaminated groundwater. Dilution is not the intent of the proposed reinjection. Reinjection will be
performed upgradient of TSF-05 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 contamination.

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 really
accomplish that much more out of it. (Tl-2)

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. As 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 jlg/L portion of the TCE plume and
institutional controls for the remainder of the plume. Alternative 3 would only meet the 100-year timeframe
for aguifer restoration if additional remediation of the less than 5,000 jlg/L 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 subseguent 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 contaminants than Alternative 3, 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, 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 and 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 finding contaminants 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. (Tl-3)

Response: New information may be generated during the Remedial Design (RD)/Remedial Action (RA) 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 change (e.g., changes that fall within the
normal scope of changes taking place during the RD/RA 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
reguire 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 concentrations drop below MCLs or risk-based levels. Any new information generated
by the remedial action will be evaluated during these periodic reviews.

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 reguiring amendment of the ROD, the
appropriate public information will be provided. In the first case, and Explanation of Significant Difference
(BSD) will be prepared. The agencies would also conduct the following public involvement activities:

• Publish a notice of availability and brief description of the BSD in a local newspaper of
general circulation, as reguired by the CERCLA, Section 117 (c) .
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• Make the BSD available to the public by placing it in the administrative record file and
information repository.

• Place the information supporting the change in the administrative record file, as well as the
lead agency's response to any comments. A Responsiveness Summary is not reguired.

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 jlg/L 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 (pCi/L). This, he maintained, violates the Clean Water Act and the
Idaho Hazardous Waste Management Act and, therefore, does not meet ARARs. The commentor concluded that
discharging Sr-90 at levels 300 times greater than the EPA's MCL of 8 pCi/L so that it can migrate back into
the aguifer is unconscionable. (W12-1, W12-2, T3-2)

Response: 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 effluent containing radionuclides at
concentrations 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 effluent will be
reinjected to the aguifer through wells designed for that purpose. The extent of radionuclide contamination
in the aguifer is limited to the hotspot in the general vicinity of the TSF-05 injection well. Therefore,
it is expected that only the portion of the remedy which focuses on the hotspot will need to address
radiocuclides.

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 technigues (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 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 contaminated groundwater would be hydraulically contained with extraction downgradient and
reinjection upgradient. The extent of radionuclide contamination 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 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-05. 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 making the decision on radionuclide removal standards. Treated effluent will be reinjected to
upgradient portions of the hotspot.

The selected remedy meets ARARs by restoring as much of the aguifer as practicable in accordance with the
Groundwater Protection Strategy presented in the National Contingency Plan. This regulation reguires 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
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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.

21. Comment: The Environmental Defense Institute (EDI) supports Alternative 4: 25 jlg/L Groundwater Plume
Extraction with Air Stripping; Enhanced Extraction of Hotspot with Above Treatment but suggests use of a
lined evaporation pond to receive the treated discharge from the filtration system at TAN. (W12-3)

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 aguifer 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 aguifer 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 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 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 contaminated groundwater would be hydraulically contained with extraction downgradient and
reinjection upgradient. The extent of radionuclide contamination 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 technology for tritium, it is expected that the effluent reinjected into the hotspot will
contain tritium.

22. Comment: A number of commentors supported proposed Alternative 3 (5,000 jlg/L) Groundwater Plume
Extraction; Enhanced Extraction of Hotspot with Aboveground Treatment. (Wl-1, W3-1, Wll-1, Tl-1, Tl-4, T2-1)

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. 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 100-year timeframe for aquifer restoration if additional remediation of the
less than 5,000 jlg/L 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 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 uncontaminated groundwater. Also
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 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)
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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. 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 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 reguires 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 reguires 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 reguires 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 aguifer restoration to drinking water standards
should not exceed 100 years. The 100-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 contaminants,
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 timeframe would be accelerated.

Therefore, the agencies agree that Alternative 4 best satisfies the CERCLA evaluation criteria.

Remedial Design/Remedial Action Concerns

24. Comment: One commentor stated that, "In 1953, the TSF Injection Well was drilled at TAN. It was used
from 1955 through 1972. The well was drilled to a depth of 310 ft. Perforations to allow deposit of injected
materials into the aguifer were placed from 180 to 244 ft and from 269 to 305 ft. Presently the aguifer is
found between its top at 200 ft and the interbed at 400 ft." (W9-1)

Proposed: 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 contaminants are present around the injection
well in the subsurface bedrock materials above the aguifer.

25. Comment: One commentor suggested that contaminants had been injected into the vadose zone in a "dry
area" approximately 20 ft above the aguifer. (W9-4) Because the water level of the aguifer has dropped
enhanced extraction technologies used as part of the selected alternative will not be effective at
decontaminating dry areas above the aguifer. He concluded that contaminants 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, contaminated area above the 200-ft mark which the proposed technigues do not
address?" (W9-6)

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. 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 contaminants and the secondary source in the
TSF injection well and not on contamination that may be present above the aguifer. If, during the course of
the RD/RA, new information becomes available that indicate contaminants are present above the aguifer that
pose an unacceptable risk to human health and the environment, the agencies will reevaluate the remedial
action in light of this new information.

Because contaminants will remain at the site above levels that would permit unlimited use and unrestricted
exposure, the NCP reguires the agencies to review the remedial action every 5 years. Thus, if the situation
envisioned by the commentor arises, the agencies are reguired by law to reevaluate the remedial action to
ensure it remains protective of human health and the environment.

All waste area groups at the INEL will perform comprehensive RI/FSs after each operable unit at the WAG has
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been evaluated. During the comprehensive RI/FS for "WAG 1, the agencies will reevaluate available data to
ensure all contaminants at TAN are or will be remediated to levels that are protective of human health and
the environment.

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 reguire a second abatement procedure?" (W9-5)

Response: The scenario of a rising waterline was not evaluated during the RI/FS 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 FFA/CO and the CERCLA. If the
scenario envisioned by the commentor occurs, it could be evaluated as new information in one of these
reviews. The RD/RA Work Plan reguires 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
1-07B) must undergo a comprehensive WAG-wide RI/FS which is scheduled to begin July-August 1995. The CERCLA
reguires that any new information received during the RD/RA phase of the cleanup be evaluated to ascertain
its impact on the selected remedial alternative. Because contaminants will remain at the site above levels
that allow for unlimited use and unrestricted exposure, the NCP reguires 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 necessary.

27. Comment: One commentor recommended that if the treatment technology is not able to extract enough
strontium to get (strontium-90 levels) down to drinking water standards, then at least (the liguid effluent)
should go into a lined evaporation pond. (T3-3) Another commentor shared this concern about using a lined
evaporation pond. (T4-2)

Response: Instead of using a percolation pond to receive effluent, the agencies propose that the treated
effluent will be reinjected to the aguifer through wells designed for that purpose. Since the extent of
radionuclide contamination in the aguifer 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 technigues (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 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 extracted groundwater. Under this "worst case" option, the extracted groundwater would be created to
remove VOCs only, and then reinjected into the upgradient portion of the hotspot. In this way, the
radiologically contaminated groundwater would be hydraulically contained with extraction downgradient and
reinjection upgradient. The extent of radionuclide contamination would decrease over time due to radioactive
decay.

28. 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.

29. Comment: One commentor urged the use of steam over other surfactants because it would be a cleaner
operation. (Tl-5)

Response: Because of the heterogeneity of the material disposed in the TSF-05 injection well, the potential
for contaminants mobilization, and the potential noncontactability of the secondary source present within the
hotspot, the proposal to use surfactant or steam has been removed.
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COMMENTS PERTAINING TO NO ACTION TRACK 1 SITES

General Technical Comments

30. Comment: Citing Table 3 (see page 14 of the Proposed Plan), a commentor asked, "How can risk-based
soil concentrations calculated from 10-6 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: acute
toxicity of solvents; explosion and fire hazards; and hazard from instability of soils composed totally of
solvents? (W6-2)

Response: A hazard quotient (HQ) was determined for the noncarcinogen risk-based concentrations and not a
10-6 risk value. Table 3 differentiated carcinogenic and noncarcinogenic contaminants by shading the
carcinogenic contaminants. 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 10-6 risk. Some sites that were evaluated were so small that essentially pure contaminant
(i.e., 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 contaminants to humans along the most sensitive and likely pathways shown in Table 3.

31. Comment: One commentor asked, "How can 46% benzene not be an inhalation hazard?" (W6-3)

Response: 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 10-6 on HQ > 1 risk (i.e., risk-based soil concentrations). The actual benzene
concentration detected 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. (Wl-5)

Response: Comment noted.

33. Comment: Two commentors disagreed about whether an indoor pathway should be evaluated in determining
the risk posed to future residential users by surface contaminants 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. (T2-3) The other
commentor stated that if contamination was present, it would not be deep enough to create an exposure pathway
to the residence. (Tl-7)

Response: 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 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.

34. 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. (Tl-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. (T2-2)

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 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 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 (LOFT)-05 Fuel Tanks

35. Comment: One commentor asked about the LOFT-05 tanks and associated piping and whether there were
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plans to upgrade the system to current underground storage tank (UST) standards? "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 LOFT-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 LOFT 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 [Transite (Asbestos) Contamination"!

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 with 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 2,500-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 reguired. 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 Facility (WRRTF)-02, -03 and -06
(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)

Response: The DOE received additional sampling information from the WRRTF-05 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 well 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-60 at concentrations greater than acceptable risk levels. The presence of Co-60 in the WRRTF-05 injection
well is from a known one-time release in the mid-1960s, and not the result of routine disposal activities at
the WRRTF. Site investigations and radiological field surveys have not detected the presence of Co-60, 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 guestions 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 guestioning past management practices,
concerns that the nuclear industry will not do the "right" thing, and disagreement amongst public meeting
commentors. These out-of-scope comments are not responded to in this Responsiveness Summary. Information on
these out-of-scope comments can be obtained from the INEL Public Affairs Office in Idaho Falls or at the
local INEL offices in Pocatello, TWIN Falls, and Boise.
-------
APPENDIX B

Public Comment/Response List

Description of Comment/Response List Index

The Public Comment/Response List Index was created to enable commentors 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 comment 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 made by the commentor.

Thirteen people submitted written comments (comments W1-W13) and four others gave oral comments at the public
meetings (comments T1-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
identify the comment code in the index, look up the comment 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.
-------
Code

Wl-1

Wl-2
Wl-3
Wl-4
W2-1
W2-2
W2-3
W3-1
W4-1
W5-1

W5-2

W5-3

W5-4

W5-5

W5-6
APPENDIX B

Public Comment/Response List Index

Commentor Comment

WRITTEN COMMENTS RECEIVED ON TAN GROUNDWATER SITES
Comment/
Response
Joseph W. Henscheid

Joseph W. Henscheid

Warren Barry

Thomas J. Setter, M.D.

Randall C. Morris
Beverly Ferrell

Beverly Ferrell

Beverly Ferrell
Alternative #3 sounds reasonable.

However, this plan ought to recognize a couple
of other possible outcomes:
(1) What if (for whatever reason) the RAOs
change during Phase 1 (10 volume removals)?

(2) After Phase 1, what if you find that
progress towards achieving the RAOs is minimal?

Seems like you might want to review the entire
approach rather than continuing pumping.
22

4
I would favor Alternative #2.
Consisting of Control.
Limited Action
The movement of the water in 40 years has been
so slight that it would pose no threat to anyone
unless they proceeded to drill a well into the area.

This seems highly unlikely since the property
should be retained for its present purpose for a
number of years in the future.

I support Alternative #3 as the final alternative
for OU 1-07B

There is no evidence that the ecological risks
from the remediation activities themselves were
considered in the evaluation of alternatives. 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. These should
be considered.

I believe the groundwater contamination should
be cleaned up as guickly as possible.

We should put no more nuclear waste in the site.

I am a victim of radiation releases near Hanford.
I lived directly across and on the river from
Richland (1947-1965).

I do not trust any government agency (or
private) when nuclear waste is concerned.

I do not believe members of the nuclear industry

will do the "right" thing.

Please do not send me any more propaganda.
14
14
14
22
OS

OS
OS
OS
OS
Page
No.
A-17

A-8
A-E
A-E
A-ll
A-ll
A-ll
A-17
A-7
A-9
W5-7
Beverly Ferrell
I have lost all respect for our government.
OS
-------
Code
APPENDIX B

Public Comment/Response List Index

Commentor Comment

WRITTEN COMMENTS RECEIVED ON TAN GROUNDWATER SITES
Comment/ Page
Response No.
W8-1
Guy Loomis
W8-2
Guy Loomis
W9-1
Rich Ravhill
W9-2
Rich Ravhill
W9-3
W9-4
Rich Ravhill
Rich Ravhill
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 $1M per cancer
death, then the action would be justified.

Suggestion: Render the scenario for residential 7 A-9
use invalid by filling in the well with bentonite,
cap the well head with concrete, and cover a 1-
acre area around the site with 2 to 4 in.-size
basalt cobble 10 ft deep. [Estimated cost $1M.]

In 1953, the TSF Injection Well was drilled at 24 A-19
TAN. It was used from 1955 through 1972.
The well was drilled to a depth of 310 ft.
Perforations to allow deposit of injected
materials into the aguifer were placed from 180
to 244 ft and from 269 to 305 ft. Presently the

aguifer is found between its top at 200 ft and the
interbed at 400 ft.

The below surface abatement technigues of 25 A-19
steam and surfactant injection (enhanced
extraction technologies of Alternative 3) only
work where water is present (i.e., within the
aguifer).
These technigues do not decontaminate dry areas
above the aguifer.
Since these will not be abated by technigues to
be implemented by proposed Alternative 3, these
contaminants will remain upon completion of the
planned remediation.

Due to decreased replenishment (drought) and 8 A-9
increased use (irrigation, etc.), the water table
has dropped.

Assuming previous water levels were higher than 25 A-19
the highest perforation (180 ft) and based upon
reports that contaminants were found throughout
the 200 to 400-ft aguifer area, it is safe to
assume contaminants are to be found within the
"hotspot" in the dry area above the top of the
aguifer at its present 200-ft level.
-------
APPENDIX B
Code
Public Comment/Response List Index

Commentor Comment

WRITTEN COMMENTS RECEIVED ON TAN GROUNDWATER SITES
Comment/
Response
Page
No.
W9-5
Rich Ravhill
W9-6
Rich Ravhill
W10-1 Mary Magleby
W10-2 Mary Magleby
Wll-1

Wll-2

Wll-3

Wll-4

W12-1

W12-2
Lee Tuott

Lee Tuott

Lee Tuott
Lee Tuott
Chuck Broscious
Chuck Broscious
If the "hotspot" above the waterline will not be 26 A-20
decontaminated 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 contamination
plume form? Will this reguire a second
abatement procedure?

What can/will be done to abate contamination in 25 A-19
this dry, contaminated area above the 200-ft
mark which the proposed technigues do not
address?
If land use is considered, is the additional cost of 15
Alternative 3 justified over Alternative 2?
Considering the flow rate of the aguifer, has the
concentration of contaminants at a point where
unrestricted access will be possible (likely) in the
future been calculated to justify the cost of
Alternative 3?
16
A-12
A-12
I support the preferred alternative.

Please provide additional information on the
proposed injection of the treated groundwater to
the aguifer.

How many injection wells would be reguired?
Where would they be sited so as to not influence
the pump/treat operations and dilute the existing
groundwater contamination?

I support the concept of reinjection of treated
groundwater due to the nonconsumptive use.

The Environmental Defense Institute supports
Alternative 4 as outlined in the RI/FS with the
following caveats.
22 A-17

2 A-6

17 A-13

9 A-10

20 A-15
20
Discharge of the "treated" groundwater that
contains Sr-90 greater than 300 pCi/L 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
technigue that has caused so much contamination
of the soil and groundwater at INEL is still used today.
Discharging Sr-90 three hundred times the EPA
MCL of 8 pCi/L so that it can again migrate
back into the aguifer is unconscionable.
A-15
-------
APPENDIX B
Code
Public Comment/Response List Index

Commentor Comment

WRITTEN COMMENTS RECEIVED ON TAN GROUNDWATER SITES
Comment/
Response
Page
No.
W12-3
Chuck Broscious
W13-1
Anonymous
W13-2
Anonymous
W13-3
Anonymous
As stated in previous comments, EDI advocates 21 A-16
the use of a lined evaporation pond to receive
the "treated" discharge from the filtration system
at TAN.

The Remedial Investigation/Feasibility Study 11 A-10
Work Plan for Operable Unit 1-07B, dated May
1992, indicates that approximately 35,000
gallons of TCE has been injected into the
aquifer. The RI/FS 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 aquifer are not considered listed
wastes for these reasons.
By the very 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 11 A-10
used TCE at the Test Area North that the bulk
of the TCE was used for cleaning operations
(i.e., 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 11 A-10
records for chemical usage before the passage of
recent environmental laws.
W13-4
W13-5
Anonymous
Anonymous
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.
11
11
A-10
A-10
-------
APPENDIX B
Public Comment/Response List Index

Code Commentor Comment

WRITTEN COMMENTS RECEIVED ON TAN GROUNDWATER SITES
Comment/
Response
Page
No.
W13-6
Anonymous
W13-7
Anonymous
W13-8 Anonymous
W13-9 Anonymous
W13-10 Anonymous
W13-11 Anonymous
W13-12 Anonymous
The Remedial Investigation/Feasibility Study 12
Work Plan for Operable Unit 1-07B, 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.
The cleanup operation was not completed in 12
accordance with the Work Package
documentation and the cleanup instructions.
Specifically, the well was to be flushed until the
effluent was clear.

At the termination of the work, the effluent was 12
still laden with contaminated sediment and
sludge.

The eguipment used to perform the cleanup 13
operation was abandoned in place at the
instruction of the EG&G Project Manager. The
eguipment was removed months later after the
EG&G Project Manager had retired.

When the pump and piping abandoned in the 13
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
liguid, which should have been disposed of as
mixed waste, was flushed back into the aguifer.

DOE should consider additional action to remove 13
the remaining sludge from the well and
determine what action to consider for removal of
the contaminants flushed back down the well.
A-10
A-10
A-10
A-ll
A-ll
A-ll
The proposed pump and treat system design does
not consider that substantial residual
contamination exists in well casing and at the
bottom of the well.
13
A-ll
-------
APPENDIX B
Code
Tl-1
Public Comment/Response List Index

Commentor Comment

ORAL COMMENTS RECEIVED ON TAN GROUNDWATER SITES
Comment/
Response
Page
No.
C. E. White
Tl-2
C. E. White
Tl-3
C. E. White
Tl-4
C. E. White
What you accomplish with remedial 22
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 18
spending all that additional money to do
[Alternative] 4 when you don't really
accomplish that much more out of it. Your
relationship between what'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 19
things which you didn't know were there.
Well, who knows, maybe in the future,
although you'll take care of those now, who
knows in the future if something else comes
up in their little head, and you have to
reassess something.

But, to me, the Remedial No. 3 would be 22
the way to go, and it would be, I think
enough protection to satisfy most anybody
that I've ever talked to about it.
A-17
A-14
A-14
A-17
-------
APPENDIX B
Code
Public Comment/Response List Index

Commentor Comment

ORAL COMMENTS RECEIVED ON TAN GROUNDWATER SITES
Comment/
Response
Tl-5
C. E. White
T2-1
Steve Novak
T3-1
Chuck Broscious
22
I would like to add one more item to what I 29
just said. We were discussing the injection
of other substances to try to, let's say,
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
whatever 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 done 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.
Page
No.
A-21
A-17
A-6
-------
APPENDIX B
Code
T3-2
Public Comment/Response List Index

Commentor Comment

ORAL COMMENTS RECEIVED ON TAN GROUNDWATER SITES
Comment/
Response
Page
No.
Chuck Broscious The one reservation that I have about the
way the treated water is being discharged is
that if, in fact, it has the concentrations of

cesium))strontium-90 at 30 picocuries
per liter, which is))I'm sorry, 300
picocuries per liter, which is almost 300
times the drinking water standard, being
discharged into something that is universally
recognized as a failed inadeguate waste
management approach, being the percolation
pond, is just really distressing to see that
that kind of continued practice is going on.
20
A-15
T3-3
Chuck Broscious
T4-1
Tom Dechert
T4-2
Tom Dechert
T4-3
Tom Dechert
I would much rather see, as we've 27
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'm like Chuck, 1
I appreciate the more open nature in the way
that the information 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 27, 28
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 addressed adeguately 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 10
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 10
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 adeguately
described the degree of contamination there.
A-20
A-6
A-20
A-21
A-10
A-10
-------
APPENDIX B
Public Comment/Response List Index

Code Commentor Comment

ORAL COMMENTS RECEIVED ON TAN GROUNDWATER SITES
Comment/
Response
Page
No.
T4-3 Tom Dechert
(Cont.)
T4-4
Tom Dechert
And I think by virtue of the fact that you're
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 the aguifer, and not only
that, but how the aguifer 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 the clays, that are occurring in
the aguifer, 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 aguifers that I don't
think are very well documented or very well
substantiated in your database.
10
A-10
-------
Code
APPENDIX B

Public Comment/Response List Index

Commentor Comment

WRITTEN COMMENTS RECEIVED ON TAN TRACK 1 NO ACTION SITES
Comment/
Response
Page
No.
Wl-5
W6-1
W6-2
Joseph W. Henscheid
Donald Brice
Donald Brice
W6-3
Donald Brice
I'm glad to see your resolution of the "No Action" 32
sites.

Table 3, Page 14. How can risk-based soil 30
concentrations calculated from 10-6 excess cancers
be calculated for noncarcinogens?

Also, how can you have greater than one million 30
parts 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?
How can 46% benzene not be an inhalation hazard? 31 A-21
A-21
A-21
W7-1
Alan Merritt
W7-2
Alan Merritt
W7-3
Alan Merritt
LOFT-05 . . . "tanks and assoc. piping remain in
place pending future use." Are you going to
upgrade this system to current UST standards? If
so, are you doing the eguivalent 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?

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 CFA landfill.
WRRTF-02-03-06 "Although no soil sampling has
been conducted ..." Why not collect some
samples and be sure?
37 A-23
-------
APPENDIX B

Public Comment/Response List Index

Code Commentor Comment

ORAL COMMENTS RECEIVED ON TAN TRACK 1 NO ACTION SITES

Tl-6 C. E. White
Comment/
Response
Page
No.
Tl-7
C. E. White
Tl-E
C. E. White
Tl-9
C. E. White
Steve Novak
T2-3
Steve Novak
T2-4
Steve Novak
T3-4
Chuck Broscious
T4-6
Tom Dechert
A-22
I can't agree totally with my friend over here about OS
the house basement, what have you.

Most of the contamination))I'm even going as far 33
as to say all of the contamination that was found on

the ground or in that area, was not of a very deep

nature. It was probably above four or five feet.
Therefore, if you go down into the ground, you're
not creating a dominant path, I don't think.
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.

I can't))I agree with most of your other things, but OS

I can't with that.

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
contaminants away.
As far as the basement scenario, contaminant not
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.

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 contaminants.

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.

I just, as a comment, I think that those wastewater 37 A-23
treatment or wastewater disposal sites, the soils
should be sampled and fully analyzed, because I
think the records are, you know, incomplete.
-------
APPENDIX C

Administrative Record

Test Area North Injection Well 07/14/94

File Number
Technical Evaluation
11.7

Document #: 5694
Title: Letter Report))Technical Evaluation of the TAN-OU 1-07B RI/FS and Proposed
Plan
Author: GeoTrans, Inc.
Recipient: EG&G Idaho, Inc.
Date: 11/30/93

R.12.1 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 Investigation/Feasibility 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's Comment on TAN OU 1-07B Draft Final RI/FS
Author: Pierre, W.
Recipient: Lyle, J. L.
Date: 01/26/94

Document #: 5697
Title: Review of Draft Final Remedial Investigation/Feasibility Study for the Test
Area North Groundwater Operable Unit 1-07B
Author: Liverman, E.
Recipient: Green, L.
Date: 01/12/94

Document #: 5698
Title: Review of Draft Proposed Plan for the Test Area North Groundwater Operable
Unit 1-07B
Author: Liverman, E.
Recipient: Harelson, D. B., English, M.
Date: 03/28/94

AR12.2 IDHW Comments

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 Investigation/Feasibility Study for Operable
Unit 1-07B
Author: English, M.
Recipient: Williams, A. C.
Date: 10/29/93

Document #: 5683
Title: Review of the 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 (RI/FS) for
Operable Unit (OU) 1-07B
Author: English, M.
Recipient: Green, L.
Date: 01/11/94
AR12.4
Document #: 5684
Title: TAN OU 1-07B Draft Final RI/FS Report
Author: Nygard, D.
Recipient: Lyle, J. L.; Pierre, W.
Date: 01/28/94
-------