EPA Superfund Record of Decision Amendment: Hanford 200-Area (USDOE) EPA Id: WA1890090078 OU 14 Benton County WA


                                   EPA/AMD/R10-97/101
                                   1997
EPA Superfund
     Record of Decision Amendment:
     HANFORD 200-AREA (USDOE)
     EPA ID: WA1890090078
     OU14
     BENTON COUNTY, WA
     09/25/1997

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    United States Environmental Protection Agency
    Region X
    1200 Sixth Avenue
    Seattle, Washington 98101
                            U.S.  Department of Energy
                    Environmental Restoration Disposal Facility
                             Hanford Site - 200 Area
                            Benton County,  Washington

                            Amended Record of Decision
                    Decision Summary and Responsiveness Summary

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TABIiE OF CONTENTS

SECTION                                                 PAGE NUMBER

DECLARATION

Site Name and Location                                       i
Statement of Basis and Purpose                               i
Assessment of the Site                                       i
Description of the Amendment to the Remedy                   i
Declaration                                                  ii

DECISION SUMMARY

Introduction                                                 1
Site History                                                 2
Remedy Selected in the ROD                                   6
Description of the Modified Remedy                           8
Evaluation of Alternatives                                   9
Selected Amended Remedy for the ERDF                         12
Statutory Determination                                      12
Documentation of Significant Changes                         12

RESPONSIVENESS SUMMARY                                       13

FIGURES
Figure 1.  Hanford Site Map                                  4
Figure 2.  Existing Disposal Cells and Phase II Expansion    5

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DECLARATION OF THE RECORD OF DECISION

SITE NAME AND LOCATION

U.S. Department of Energy
Environmental Restoration Disposal Facility
Hanford Site - 200 Area
Benton County, Washington

STATEMENT OF BASIS AND PURPOSE

This Record of Decision (ROD) Amendment has been developed in accordance with the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), 42 U.S.C. Section 9601 et. seg, and to the extent practicable, the
National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 Code of Federal Regulations (CFR)
Part 300. This ROD Amendment is based on the Administrative Record for the Environmental Restoration
Disposal Facility.

The State of Washington concurs with the ROD Amendment.

ASSESSMENT OF THE SITE

Actual or threatened releases of hazardous substances from the operable units on the Hanford Site, if not
addressed by implementing the response action selected in the ROD, as changed by this ROD Amendment, may
present an imminent and substantial endangerment to the public health, welfare, or the environment.

DESCRIPTION OF THE AMENDMENT TO THE REMEDY

The changes to the original ROD addressed in this Amendment are explained in the following sections.

ERDF Expansion. The ERDF ROD specifies that expansion of the facility would be authorized as-needed through
the ROD amendment process. Based on estimated remediation waste volumes presented in the ERDF ROD,
additional disposal cells were anticipated. This Amendment authorizes two additional ERDF cells to be
constructed and operated for disposal of Hanford Site remediation waste. The Phase II construction shall be
located entirely within the 4.1 sguare kilometer (1.6 sguare miles) area selected for ERDF, as defined in the
ERDF ROD.

The approved design of ERDF is a single, 70-ft-deep trench consisting of two side-by-side cells with final
dimensions of 1,420-ft long by 720-ft wide at the top of the trench. The facility is eguipped with a RCRA
double-liner and leachate collection and recovery system. The same RCRA design selected for the existing
ERDF disposal cells shall be used for the Phase II cells. The design phase shall also include an evaluation
of vadose zone monitoring. The detailed design shall be submitted to the EPA for approval prior to
construction of the ERDF facility.

Treatment at ERDF. The selected remedial alternative in existing 100 and 300 Area waste site remediation
RODs is removal, treatment if reguired, and disposal at ERDF. Treatment would be reguired if the
concentration of contaminants in the waste is above land disposal restriction standards found in the Federal
and State hazardous waste regulations or above the ERDF waste acceptance criteria. This Amendment provides
the option of conducting remediation waste treatment in containers at ERDF instead of the operable unit,
prior to disposal. This option does not preclude treatment at the operable units. Treatment at ERDF would
be limited to stabilization in containers and encapsulation. In addition, all substantive federal and state
reguirements governing hazardous waste treatment in containers, such as secondary containment, shall be met
as part of treatment at ERDF. The decision whether to perform remediation waste treatment, and the specific
treatment needed, will be documented as part of the remedy selection and remedial design process for the
operable unit or waste site of origination. The decision concerning where treatment occurs would be made in
coordination with ERDF.

DECLARATION

Although this ROD Amendment changes components of the remedy selected in the original ROD, the remedy, as
modified, continues to be protective of human health and the environment. The remedy, as amended, complies
with Federal and state reguirements that are legally applicable or relevant and appropriate and is cost
effective. This remedy utilizes permanent solutions to the maximum extent practicable for this site.
Treatment of wastes will be addressed in the operable unit decision documents. As a conseguence, the
statutory preference for treatment as a principal element will be addressed in those current and future
documents rather than in this ROD.

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Because this remedy will result in hazardous substances remaining on site above health-based levels, a review
will be conducted at least every five years after the commencement of remedial actions to ensure that the
remedy continues to provide adequate protection of human health and the environment.

Signature sheet for the Amendment to the Record of Decision for the USDOE Hanford Environmental Restoration
Disposal Facility between the United States Department of Energy and the United States Environmental
Protection Agency, with concurrence by the Washington State Department of Ecology.

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DECISION SUMMARY

USDOE Environmental Restoration Disposal Facility
Record of Decision Amendment

I. INTRODUCTION

This document presents an Amendment to the Record of Decision (ROD) for the Environmental Restoration
Disposal Facility at the Hanford Site.

Site Name and Location

USDOE Hanford Environmental Restoration Disposal Facility
Hanford Site - 200 Area
Benton County, Washington

Lead and Support Agencies

The lead regulatory agency for this action is the U.S. Environmental Protection Agency (EPA) . The U.S.
Department of Energy (DOE) and the Washington Department of Ecology (Ecology) both concur with the need and
justification to increase the size of the disposal facility and allow for stabilization and encapsulation
capabilities at the ERDF site. The three agencies participated jointly in the decision and preparation of
this document.

Statutory Citation for a ROD Amendment

The Environmental Restoration Disposal Facility (ERDF) ROD was signed by the EPA, Ecology, and the DOE in
January 1995. In 40 CFR °300.435(c) (2) the National Contingency Plan provisions are specified for addressing
and documenting changes to the selected remedy after issuance of a ROD. An Explanation of Significant
Differences (BSD) was issued in August of 1996. This ROD Amendment documents fundamental changes to the
remedy set forth in the 1995 ERDF ROD. Public participation and documentation procedures have been followed
as specified at 40 CFR 300.435(c) (2) (ii) .

Need for the ROD Amendment

This amendment is necessary for the following reason:

The ERDF is currently identified in the 100 Area ROD and ROD Amendment, the 300 Area ROD, and
several Removal Action Memoranda as the location to dispose of waste resulting from actions in
these areas. The estimated waste volume to be generated from these actions is 1.5 to 2.0
million cubic yards. The total capacity of the existing disposal facility is approximately one
million cubic yards. Expansion is necessary to continue remediation of the Hanford Site.

Public Involvement

A newspaper notice was placed in the Tri-City Herald on August 3, 1997 announcing the availability of the
proposed amendment and the start of the public comment period. Approximately fourteen hundred copies of a
fact sheet describing the amendment proposal were mailed out. A public comment period was held from August 4
through September 3, 1997. No reguests were received for a public meeting, therefore, no public meeting was
held. Copies of the proposed plan were provided to the Hanford Advisory Board (HAB) Environmental
Restoration (ER) Committee members. The proposed amendment was discussed with the HAB and the HAB-ER
Committee at meetings in June, July, August, and September of 1997. The decision to amend the ROD is based
on the Administrative Record for the ERDF. Locations where the Administrative Record may be found are listed
below.

Administrative Record

This ROD Amendment will become part of the Administrative Record for ERDF, as reguired by 40 CFR
300.825(a)(2), and will be available to the public at the following locations:

ADMINISTRATIVE RECORD (Contains all project documents)

U.S. Department of Energy - Richland Operations Office
Administrative Record Center
2440 Stevens Center
Richland, Washington 99352
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INFORMATION REPOSITORIES (Contain limited documentation)

University of Washington Gonzaga University, Foley Center
Suzzallo Library E. 502 Boone
Government Publications Room Spokane, Washington 99258
Seattle, Washington 98195

Portland State University DOE Richland Public Reading Room
Branford Price Millar Library Washington State University, Tri-Cities
SW Harrison and Park 100 Sprout Road, Room 101L
Portland, Oregon 97207 Richland, Washington 99352

II. SITE HISTORY

In 1988, the Hanford Site was scored using the EPA's Hazard Ranking System. As a result of the scoring, the
Hanford Site was added to the NPL in July 1989 as four sites (the 1100 Area, the 200 Area, the 300 Area, and
the 100 Area). Each of these areas was further divided into operable units (a grouping of individual waste
units based primarily on geographic area and common waste sources). These operable units contain
contamination in the form of hazardous waste, radioactive/hazardous mixed waste, and other CERCLA hazardous
substances.

In anticipation of the NPL listing, DOE, EPA, and Ecology entered into the Hanford Federal Facility Agreement
and Consent Order in May 1989. This agreement established a procedural framework and schedule for
developing, implementing, and monitoring remedial response actions at Hanford. The agreement also addresses
RCRA compliance and permitting.

The fundamental objective of ERDF is to support the timely removal and disposal of contaminants from various
locations within the Hanford Site. Several Hanford Site remediation RODs and Removal Action Memoranda
identify ERDF as the location for disposal of resulting waste. The Hanford Site and ERDF location are shown
on Figure 1.

Construction of the first two ERDF disposal cells began in February 1995, and the first waste was placed in
ERDF on July 1, 1996. As of June 30, 1997, ERDF has received 248,256 cubic yards of waste. The ERDF is
scheduled to accept approximately 360,000 cubic yards of waste material in fiscal year 1997. The two
operating disposal cells have a total maximum waste capacity of approximately one million cubic yards. In
addition to the disposal cells, the ERDF site contains a transportation staging area, an administration
building, worker offices and a change trailer, a waste container staging area, leachate collection tanks, a
spoils pile used for daily operational cover, an employee parking area, a truck scale, and haul roads.

The layout and size of the existing and proposed Phase II cells are shown in Figure 2. The deep,
single-trench configuration used for the first two cells and selected for Phase II construction minimizes the
areal extent of the waste facility and offers the following advantages in comparison to other configurations:

• Less habitat disruption
• Reduced material needs
• Reduced leachate generation
• Lower costs for the trench liner and the interim and final covers.

The operation of ERDF has proven to be a cost-effective means to handle Hanford Site remediation waste. To
date, the operating cost to dispose of waste at ERDF has averaged approximately $30 per cubic yard from the
start of operation. The total life-cycle costs for the facility eguate to approximately $80 per cubic yard.
No other more cost-effective waste disposal alternative has yet been identified to handle Hanford Site
remediation waste.

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III. REMEDY SEIiECTED IN THE ROD

The major components of the selected remedy implemented as a result of the 1995 ERDF ROD include the
following:

• Initial construction and operation of the first two disposal cells. These cells are expected
to provide an approximate waste disposal capacity of one million yd 3. The cells are designed
and constructed to RCRA minimum technological reguirements (MTRs) (40 CFR Part 264, Subpart N).
The decisions to expand the landfill in the future will be documented by amending the ERDF ROD
or as part of the RODs for the Hanford operable units.

• The ERDF site will cover a maximum of 4.1 km 2 (1.6 mi 2) on the Central Plateau, southeast of
the 200 West Area and southwest of the 200 East Area. The initial construction of the facility
reguired 165 acres of this area.

• The ERDF facility will provide sufficient leachate storage capacity to ensure uninterrupted
operations, and will comply with 40 CFR Part 264, Subpart N.

• Surface water run-on/run-off will be controlled at the landfill and other areas of the facility
that are potentially contaminated.

• Air monitoring will be accomplished by placement at ERDF of real-time air monitors for
radioactive contaminants and air samplers for hazardous and radioactive constituents to detect
any offsite migration of contaminants. The current air monitoring system satisfies this
reguirement.

• Groundwater monitoring will be performed in accordance with 40 CFR Part 264, Subpart F. The
current monitoring system complies with these reguirements.

• Appropriate measures to protect facility workers and the public will continue to be employed
during ERDF operations, including contamination control and dust mitigation, and protection of
personnel from industrial hazards presented by ERDF operations. Protective measures shall
comply with applicable reguirements found in the Occupational Safety and Health Act (OSHA),
Washington Industrial Safety and Health Act (WISHA) , and other safety regulations or
ERDF-specific safety reguirements. Energy shall also comply with 40 CFR °300.150.

• Waste acceptance criteria have been developed by DOE and approved by EPA in accordance with
applicable or relevant and appropriate reguirements (ARARs), risk/performance assessments,
ERDF-specific safety documentation, and worker protection reguirements. Operable unit-specific
waste disposal and treatment decisions will continue to be made as part of the remedy selection
and cleanup decision process for each operable unit.

• The ERDF landfill will be closed by placing a modified RCRA-compliant closure cover over the
waste. The cover will prevent direct exposure to the waste and will include a vegetated
surface layer of fine-grained soils to retain moisture and encourage evapotranspiration,
thereby minimizing infiltration and vadose zone transport of contaminants to groundwater. The
upper 50 cm (20 in.) of the soil cover system will be composed of an admixture of silt and
gravels. This layer is intended to both reduce infiltration through the cover and enhance the
resistance of the cover to burrowing animals and long-term wind erosion. The RCRA-compliant
cover will be modified by providing a total of approximately 15 feet of cover material to deter
intrusion. It is anticipated that additional research into closure covers may result in
site-specific enhancements to RCRA-compliant designs. Prior to cover construction, closure
cover designs will be evaluated and the most appropriate closure cover design will be selected
for construction. Construction of the cover will occur on an incremental basis, as the trench
is expanded. The design will, at a minimum, comply with applicable RCRA reguirements found at
40 CFR Part 264, Subpart N. Basalt from Hanford Site borrow pits will not be reguired for
construction of the ERDF closure cover.

• Institutional controls shall be imposed to restrict public access to the landfill. Current
Hanford Site access restrictions are in place.

• Wash water used to decontaminate site eguipment shall be managed in accordance with
appropriate reguirements. The approved operations plan addresses handling of decontamination
waters.

• An ERDF operations plan has been approved by EPA.
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• DOE commits to the implementation of the Mitigation Action Plan developed in coordination with
the Natural Resource Trustees for additional mitigation measures.

The Explanation of Significant Differences to the ERDF ROD, issued in July of 1996, documented authorization
of the following changes:

• Any Hanford environmental cleanup waste generated as a result of CERCLA or RCRA cleanup actions
(IDW, decontamination and decommissioning wastes, RCRA past-practice wastes) is eligible for
disposal provided it meets the ERDF Waste Acceptance Criteria and provided that the appropriate
decision documents are in place. Additionally, nonprocess waste (e.g., contaminated soil,
debris) generated from closure of inactive RCRA TSD units may be placed in ERDF provided that
the units (1) are within the boundaries of a CERCLA or RCRA past-practice operable unit, (2)
the closure wastes are sufficiently similar to CERCLA or RCRA past-practice wastes placed in
ERDF, (3) the ERDF waste acceptance criteria are satisfied, and (4) the appropriate CERCLA
decision documents are in place. Revision of the RCRA Permit and closure plans may be reguired.

• The ERDF leachate may be collected and stored at the ERDF for use within the trench, as
appropriate. Appropriate uses are limited to dust suppression and waste compaction. The
leachate must be sampled prior to use to ensure compliance with Land Disposal Restrictions
(LDRs), ERDF waste acceptance criteria, and other health-based limits (whichever is more
restrictive). Leachate in excess of ERDF recycling capacity or acceptable contaminant levels
will be sent to the Effluent Treatment Facility or another approved facility for management.

IV. DESCRIPTION OF THE MODIFIED REMEDY

The changes to the original ROD addressed in this Amendment are explained in the following sections.

ERDF Expansion. The ERDF ROD specifies that expansion of the facility would be authorized as-needed through
the ROD amendment process. Based on estimated remediation waste volumes presented in the ERDF ROD,
additional disposal cells were anticipated. Two additional ERDF cells shall be constructed and operated for
disposal of Hanford Site remediation waste. Remediation volume estimates in final and planned cleanup
decision documents, prepared since the ERDF ROD was issued, support the need for additional capacity. The
Phase II construction shall be located entirely within the 4.1 km 2 (1.6 mi 2) area selected for ERDF, as
defined in the ERDF ROD.

The current design of ERDF is a single, 70-ft-deep trench consisting of two side-by-side cells with final
dimensions of 1,420-ft long by 720-ft wide at the top of the trench. The facility is eguipped with a RCRA
double-liner and a leachate collection and recovery system. The same RCRA design selected for the existing
ERDF disposal cells shall be used for the Phase II cells. The design phase shall also include an evaluation
of vadose zone monitoring. The detailed design shall be submitted to the EPA for approval prior to
construction of the ERDF.

Treatment at ERDF. The selected remedial alternative in existing 100 and 300 Area waste site remediation
RODs is removal, treatment if reguired, and disposal at ERDF. Treatment would be reguired if the
concentration of contaminants in the waste is above land disposal restriction standards found in the Federal
and State hazardous waste regulations or above the ERDF waste acceptance criteria. This Amendment provides
the option of conducting remediation waste treatment at ERDF instead of the operable unit, prior to disposal.
This option does not preclude treatment at the operable units. Treatment at ERDF would be limited to
stabilization and encapsulation in containers. In addition, all substantive federal and state reguirements
governing hazardous waste treatment in containers, such as secondary containment, shall be met as part of
treatment at ERDF. The decision whether to perform remediation waste treatment, and the specific treatment
needed, will be documented as part of the remedy selection and remedial design process for the operable unit
or waste site of origination. The decision concerning where treatment occurs would be made in coordination
with ERDF.

V. EVALUATION OF ALTERNATIVES

The NCP establishes nine criteria for evaluating remedial action alternatives. These criteria are divided
into three categories of weighted importance which include: threshold, balancing, and modifying criteria.
All remedies must meet the threshold criteria to be considered. The seven balancing and modifying criteria
help describe relative differences between the alternatives. A discussion of the original remedy and the
modified remedy relative to the nine criteria evaluation is reguired by CERCLA.
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Summary of Alternatives

The key elements of each alternative are described and briefly discussed below.

• Alternative 1 - No Action. The no action alternative consists of not constructing the Phase
II expansion of the ERDF trench to accommodate additional waste from waste site remediation.

Alternative 2 - ERDF Phase II Construction. Two additional cells would be constructed at ERDF
to provide additional capacity for ongoing remediation of the 100, 200 and 300 Areas.

• The ERDF Phase II construction would use the same design as the first two disposal cells;
therefore, the previous evaluation of the threshold and balancing criteria in the 1995 proposed
plan and ROD remains applicable.

• Alternative 3 - Treatment at the Operable Unit. Treatment would continue to be performed only
at the operable unit.

Alternative 4 - Treatment at ERDF. Treatment of waste coming from 100, 200 and 300 Area
remedial actions and from deactivation and decommissioning activities would be performed at the
ERDF. Treatment determinations would still be documented as part of the remedy selection
process for the operable unit or decontamination and decommissioning activity. This option
does not preclude treatment at the operable units.

Threshold Criteria

1. Overall Protection of Human Health and the Environment

The no action alternative does not satisfy the criterion of overall protection of human health and the
environment. Once the original ERDF capacity was utilized, remediation of the 100 and 300 Areas would cease
unless alternative disposal options could be developed. For this reason, the no action alternative is not
evaluated further.

The construction of the expansion would satisfy overall protection of human health and the environment. The
same approach to treatment would be implemented whether treatment was conducted at ERDF or at the operable
unit where the waste originated. Therefore, both alternatives will be egually protective of human health and
the environment, effective in the short-term and long-term, and implementable.

2. Compliance with Federal or State Environmental Standards (ARARs)

The existing ERDF ROD and this amendment will both comply with ARARs. The key ARAR for the facility is the
Resource Conservation and Recovery Act - Title 42 USC 6901 et seg., Subtitle C. The Resource Conservation and
Recovery Act (RCRA) regulates the generation, transportation, storage, treatment, and disposal of hazardous
waste. These regulations also provide authority for the cleanup of spills and environmental releases of
hazardous waste to the environment as a result of past practices. Hazardous waste management regulations
promulgated pursuant to RCRA are codified at 40 CFR Part 260 through 268. Washington State Dangerous Waste
Regulations implement the federal hazardous waste regulations and are administered by Ecology. These state
regulations are codified in Chapter 173-303 of the Washington Administrative Code ("WAG"). Regulations
established under RCRA are applicable to the ERDF because the facility is expected to receive hazardous waste
and operation of the facility may generate hazardous waste.

The most significant ARARs for construction and operation of the disposal facility receiving
hazardous/dangerous waste include federal RCRA landfill reguirements specified in 40 CFR Part 264, Washington
State dangerous waste landfill reguirements specified in WAG 173-303-665, RCRA LDRs specified in 40 CFR Part
268 and WAG 173-303-140, and Toxic Substances Control Act (TSCA) reguirements specified in 40 CFR Part 761.

The key ARARs for the storage and treatment of waste at the ERDF are specified in 40 CFR Part 268 Subpart E -
Prohibitions on Storage; and 40 CFR Part 264 Subpart I and WAG 173-303-630 - Use and Management of
Containers.

Balancing Criteria

3. Long-term Effectiveness and Permanence

Expansion of the ERDF would provide long term isolation of waste coming from remedial actions at the Hanford
Site.

The effectiveness of treatment by stabilization or encapsulation would be the same, regardless of where
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treatment is performed.

4. Reduction of Toxicity, Mobility, and Volume Through Treatment

Treatment of the incoming waste at ERDF is part of this ROD amendment and only includes stabilization and
encapsulation. Waste treatment will generally be considered in the feasibility studies, proposed plans,
RODs, and design documents for the individual operable units. Waste coming to and treated at the ERDF shall
meet all ARARs and satisfy ERDF waste acceptance criteria prior to disposal.

The goal of treatment by stabilization or encapsulation is reduction of mobility and subseguent reduction of
toxic elements released to the environment. The same reduction of mobility and toxicity would be
accomplished regardless of the location where treatment is performed.

5. Short-Term Effectiveness

The existing ERDF ROD and this amendment have the same approach to construction of the facility. Therefore,
both are essentially the same with respect to meeting this criterion,

Risks posed to the community, workers, or the environment as a result of the treatment location would be
negligible. Environmental risk would be lower at the operable unit due to treatment being done prior to
shipment.

6. Implementability

Similar to Phase I, the Phase II expansion has a double liner. Therefore, the complexity of the task ranks
low in terms of technical implementability.

Stabilization or encapsulation treatment technology is considered implementable regardless of the location.
A single centralized treatment location is considered more efficient and, therefore, less difficult to
implement than providing separate treatment units at each remedial action site. An added advantage would
likely be consistency of the treatment technology when applied at a central location rather than at several
different locations.

7. Cost

The estimated cost in the existing ERDF ROD was $65 million. The actual cost for the facility design and
construction was $45.8 million. It is estimated the construction of the next two disposal cells would cost
approximately $18 million from design through the start of operation.

Costs for conducting treatment activities at ERDF are considered to be less than conducting treatment at each
operable unit based on the amount of material to be shipped. Also, a centralized treatment area would reduce
the need for multiple treatment systems and associated contracts and operating expenses. A reduction in
transportation and handling costs would also be realized as the treatment agents (e.g., cement), which
increase the volume and weight, would be added to the waste after shipment to ERDF. The cost to transport to
and handle waste at ERDF is approximately $50/ton.

Modifying Criteria

8 . State Acceptance

The State of Washington has concurred with this amendment.

9. Community Acceptance

Newspaper notices, a fact sheet, and a proposed plan were issued to support starting public comment on August
4, 1997. Several comments were received during the 30-day public comment period. The comments were
generally in support of the amendment and are included in the Responsiveness Summary that is attached to this
Amendment.
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VI. SEIiECTED AMENDED REMEDY FOR THE ERDF

A combination of alternatives two and four is considered the best option because these options provide for
continuous remediation of the Hanford Site in accordance with current RODs and Action Memoranda and provide a
cost-effective option for treatment of waste materials being sent to the ERDF under those RODs and Action
Memoranda. A detailed description of the selected amended remedy is found in Section IV (Description of the
Modified Remedy) of this Amended Record of Decision for the ERDF. The ARARs for this amended remedy are
unchanged from those specified in the 1995 ERDF ROD.

VII. STATUTORY DETERMINATIONS

The EPA and Ecology believe that the amended ROD remains protective of human health and the environment,
complies with Federal and State reguirements that are applicable or relevant and appropriate to this remedial
action, and is cost-effective. This remedy utilizes permanent solutions to the maximum extent practicable
for this site. Treatment of wastes will be addressed in the operable unit decision documents. As a
conseguence, the statutory preference for treatment as a principal element will be addressed in those current
and future documents rather than in this ROD.

VIII. DOCUMENTATION OF SIGNIFICANT CHANGES

DOE and EPA reviewed all written and verbal comments submitted during the public comment period. Upon review
of these comments, it was determined that no significant changes to the amended remedy, as originally
identified in the Proposed Plan, were necessary.
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IX. RESPONSIVENESS SUMMARY

U.S. Department of Energy
Environmental Restoration Disposal Facility
Hanford Site
Benton County, Washington
Amended Record of Decision

Introduction

This responsiveness summary meets the reguirements of Section 117 of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) as amended. The purpose of this responsiveness summary is
to summarize and respond to public comments on the proposed amendment for the January 1995 Record of Decision
(ROD) for the Hanford Environmental Restoration Disposal Facility. The proposed plan for the Amendment,
issued on August 4, 1997, was presented for public comment on the proposed changes to components of the
remedy set forth in the January 1995 ROD.

The Tri-Parties announced the issuance of the proposed plan in the community newspaper. A thirty-day comment
period was provided for the public to read the proposed plan, review documents in the administrative record,
and submit written comments. No reguest was made for a public meeting, therefore, no meeting was held. The
proposed plan discussed expansion of the Environmental Restoration Disposal Facility by two additional cells
and included the option of waste treatment at the facility, limiting it to stabilization and encapsulation of
waste.

Community Involvement

The proposed amendment was presented to the Hanford Advisory Board (HAB) and the HAB Environmental
Restoration Committee in June, July, August, and September 1997.

Comments and Responses

The following advice was received from the Hanford Advisory Board.

1. The HAB supports both elements of the Proposed Plan for an Amendment to the Environmental Restoration
Disposal Facility Record of Decision: (a) construction of Phase II of ERDF for disposal of Hanford Site
waste only, and (b) authorization for treatment of Hanford Site waste at ERDF.

Response: Thank you for your comment.

2. The HAB recommends that the DOE report the full cost for disposal of waste at ERDF including costs of
design, construction, maintenance, monitoring, mitigation, and closure. U.S. DOE should use the full cost of
disposal at ERDF when comparing the costs of other remediation technologies.

Response: The cost of $30 per cubic yard noted in the Proposed Plan reflects operating costs only. When the
additional costs of design, construction, transportation, operation, monitoring, and closure are factored in,
the life cycle cost of the facility is approximately $80 per cubic yard. Both of these numbers are reflected
in the ROD Amendment. A formal response has been prepared to address the costs in detail and will be
submitted to the HAB.

The following comments were received from the Confederated Tribes and Bands of the Yakima Indian Nation.

The Yakima Indian Nation cannot endorse the proposed ERDF expansion until a number of technical guestions are
answered. We expect that many of the following guestions have been addressed in previous documents and could
be answered by providing us with the citation and the actual document where the issues were addressed.
However, in order to meet your deadline for comment of September 3, we are responding to the proposed
expansion with a series of guestions to be followed later by a letter accepting or rejecting the proposal
depending on the answers to the guestions.

Response: A formal response addressing the guestions provided by the Yakima Indian Nation has been prepared
by the Department of Energy (DOE) and Environmental Protection Agency (EPA) . Many of the comments do not
focus on the expansion of the facility. Rather, the comments deal with the facility as a whole. DOE and EPA
will continue to work with the Yakima Indian Nation in resolving the concerns.

1. Do excavated soil volume estimates still match the original estimates? What are those volumes, and what
is the process for feeding new information about disposal needs into ERDF containment performance
reguirements and waste acceptance criteria?
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Response: Estimates of the total volume of waste have decreased since the ROD was published The ROD states
the following, "The total volume of waste is expected to be less than 21.4 million m 3 . . . ". The current
estimate of total waste volume is four million m 3. Risk and performance analyses were based on the higher
volumes published in the ROD and were modeled at higher concentration than are actually being encountered.
Thus, no plans exist at this time for updating the ERDF containment performance reguirements and waste
acceptance criteria. Waste acceptance criteria revisions will be performed, as appropriate and when needed,
to address additional information as it becomes available.

2. What is the total amount (inventory) in cells 1&2 (volumes, contaminants, concentrations, total curies
and guantities)? What is anticipated for cells 3&4? What was used as the original analysis in the RI/FS?

Response: The total volume in cells 1&2 is approximately 204,900 m 3 as of August 29, 1997. The total
curies disposed at ERDF is approximately 1,800 Ci. This value is conservative in that where a "non-detect"
is identified in the waste profile, the defection limit is used as the curie content for that radionuclide.
Radionuclide and dangerous waste constituents are being tracked in a site-specific database managed by Waste
Management Federal Services. Remediation is being focused first on waste sites with the highest anticipated
concentrations of contaminants in the 100 and 300 Areas. Therefore, it is anticipated the total curies in
cells 3&4 will be less than what will exist in cells 1&2. The original analysis used the maximum
concentrations reported and assumed this concentration for the total volume of the waste being disposed in
ERDF.

3. What exactly has been put into ERDF so far (soil, rubble, debris, etc.)? How is it mapped in case
something specific needs to be retrieved?

Response: The predominant waste form received by the ERDF has been soil. Additionally, contaminated
concrete rubble and steel debris has been received. The ERDF trench has a 30ft grid system that is used to
record the location of each container or discrete objects placed in the trench.

4. What containment assumptions are most current? What updates are there on the barrier testing program?
If that program is slated for discontinuance (and the probes removed), how will long-term performance be
validated? Is any monitoring planned as long as the test barrier is there?

Response: The final cover will be a RCRA-compliant, Subtitle C cover that has a permeability less than that
of the liner. The Hanford Prototype Barrier testing program has completed three years of field testing EPA
and DOE have agreed to continue with the testing program in fiscal year 1998 at a reduced level of
monitoring. A site-wide evaluation of barrier performance needs is being done and additional funding from
other programs within DOE is being discussed.

5. Do any of the following items need revisiting for analysis or underlying assumptions:
a. The Native American subsistence scenario was not developed then-does it need to be added now? If
not now, when?

Response: The risk scenarios developed for ERDF were based on current regulations and guidance for
evaluating human and ecological risk. Further evaluation may be expanded to include the subsistence scenario
at closure.

b. If a 500 year intruder scenario was used, we also need a 100 year intruder scenario;

Response: A performance analysis specified that inadvertent intrusion (post-closure drilling scenario)
cannot occur until loss of institutional control, which was defined as 100 years. If the facility contains
contaminants that are persistent beyond 100 years, and relies on passive controls for the deterrence of
intruders, the time of compliance was defined as 500 years. Although the ERDF is assumed to use passive
controls (making the time of intrusion 500 years post-closure for the drilling scenario), total dose
calculations for the post-drilling scenario were done for 100, 300, and 500 years.

c. How does ERDF fit into the 200 Area composite source term and the entire Sitewide source term?

Response: ERDF is considered as a single source term that is integrated into the final composite analysis.
The composite analysis uses the current volume estimates (see response to #1) and maximum concentrations
reported in the ERDF Remedial Investigation and Feasibility Study (RI/FS). The 200 Area composite analysis
is synonymous with the sitewide and assumes all areas outside the 200 Area plateau are cleaned up.

d. What kind of composite risk profile was done (including socio-cultural risks, impacts, and values)?
Was anything done beyond simple dose calculations?

Response: A baseline risk assessment was conducted to determine the human and ecological impacts associated
with waste disposal in ERDF under various scenarios. Risks are expressed in terms of incremental cancer risk
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and hazard quotients for both radiological and non-radiological contaminants, as appropriate.

The scope of the ERDF RI/FS was expanded to address NEPA values not normally considered, such as
socioeconomic and cultural resources. Socio-cultural risks were not specifically addressed

e. What is the groundwater point of compliance for ERDF? How does that POC fit into other POCS?

Response: The point-of-compliance (POC) for ERDF is the point where groundwater intersects a vertical plane
projected from the surface at the edge of the facility. For the composite analysis the POC is the edge of
the 200 Area buffer zone, and for the Hanford Site low-level waste burial ground it is 100 meters down
gradient of the facility.

6. What is the total time frame of analysis? What is the total long-term risk profile?

Response: Both performance dose calculations and the risk analyses were done based on a time frame of 10,000
years. Because of the various scenarios considered, the reader is referred to the RI/FS and Performance
Assessment for a detailed discussion of long-term risk profiles.

7. Are the original groundwater and vadose models still adequate for predicting environmental releases and
waste acceptance criteria? What process is there for refining the WAG and containment performance
assessments as the groundwater and vadose models are further refined?

Response: Groundwater and vadose models used in the ERDF RI/FS are still considered to be representative of
predicted conditions. Characterization of the vadose zone at the ERDF site quantified both stratigraphic
profiles and physical properties. Ongoing groundwater monitoring at the site has demonstrated an increase in
the depth to groundwater beneath the site due to dissipation of 200 West Area mounding. Original predictions
for environmental releases and waste acceptance are very conservative and therefore still considered to be
well within acceptable limits being applied to ERDF waste receipt. The most stringent ERDF acceptance limits
are derived primarily from the more conservative regulatory requirements (e.g., land disposal restrictions,
TSCA, radionuclide waste classification) rather than by calculated risk limits.

8. What performance assumptions were used to set the original waste acceptance criteria? On what additional
factors were WAG based? Were the WAG based on a composite Sitewide analysis evaluating long-term
(post-closure) releases and impacts from ERDF as well as all other 200 Area and Sitewide (including the 100
Area) sources? What is the process for refining the WAG as more complete information is received?

Response: The waste acceptance criteria for radioactive constituents were developed to ensure that waste
accepted for disposal could not result in potential doses in excess of the performance objectives. The
primary waste acceptance criteria are radionuclide-specific concentration limits (ci/m 3)for isotopes with
half-lives greater than five years and total-activity limits (Ci) for long-lived environmentally mobile
radionuclides. Second, compliance with performance objectives was evaluated by estimating potential dose
resulting from the disposal of the entire projected inventory of low-level waste in the ERDF. This
evaluation included a long-term (post-closure) evaluation for the ERDF source term only.

A risk-based screening process and comparison to applicable or relevant and appropriate requirements was used
to identify contaminants of potential concern. The risk-based screening process involved the calculation of
risk-based screening concentrations that correspond to a hazard quotient of 0.1, or incremental cancer risk
of 1x10 -7 using residential scenario exposure parameter values. These screening values are an order of
magnitude less than the Comprehensive Environmental Response Compensation and Liability Act (CERCLA)
risk-based criteria.

WAG revisions will be performed, as appropriate and when needed, to address additional information as it
becomes available.

9. What waste treatment is anticipated?

Response: The only treatment currently identified is for lead encapsulation. However, other waste streams
may need to be treated to meet applicable regulatory limits. The most likely treatment alternative would be
stabilization or encapsulation to allow the waste to be disposed of at ERDF. Thus, the Proposed Plan
discusses both stabilization and encapsulation as potential treatment methods at ERDF.

10. Please provide a copy of the Safety Analysis (BHI-00370, Rev. 2).

Response: A copy was provided on September 15, 1997.

11. What are the total volume projections and how many total cells will be needed? How will DOE guarantee
that only on-site waste will be disposed of, and how are the ultimate total limits determined and enforced?
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Response: The total volume projections are provided in response to question #1 above. Currently, it is
anticipated that a total of eight cells will be needed to accommodate this volume.

The authorization basis for the ERDF is the ROD. The ROD states that only waste originating from the
remediation of operable units within the 100, 200, and 300 Area National Priorities List (NPL) sites of
Hanford is eligible for disposal at ERDF. Each remediation originating waste for disposal at ERDF must have
approved CERCLA authorization documentation before ERDF will accept it.

DOE has developed, and EPA has approved, the ERDF Waste Acceptance Criteria (WAG). This WAG requires a waste
profile for all waste entering ERDF. This profile is reviewed by ERDF operations prior to disposal.

12. What is the process by which other projects guarantee that their wastes will be characterized adequately
to be accepted by ERDF? How does ERDF know exactly what other projects are planning to send ERDF? Do the
current ERDF volume estimates include those plans of other projects?

Response: According to the waste acceptance criteria (see response to #11), each waste generator must
characterize their waste sufficiently to produce a waste profile. A combination of process knowledge,
historic information, characterization data, and ongoing field characterization during remediation are used
to profile the waste. The ERDF compares the waste profile to the waste acceptance criteria to verify that
the waste is acceptable for placement in the ERDF.

All waste received for disposal in ERDF must have an approved CERCLA decision document in place. In
addition, projected waste volumes from all projects are rolled up in the detailed work plan. This plan is
the basis for long-range volume forecasts for the ERDF.

13. What natural resources mitigate on has been planned in response to the total area impacted by
ERDF?

Response: For the current expansion, an Inter-Agency Agreement between DOE and the U.S. Department of Fish
and Wildlife has been drafted and is expected to be issued by the end of September 1997. The agreement will
provide the basis for planting sagebrush on naturally disturbed areas of the Arid Lands Ecology reserve. In
addition, a Natural Resources Trustee Council Subcommittee has been formed to provide input to the
development of the revegetation plan. Although the total area impacted by ERDF will not be known until
remediation is completed, it is anticipated that any further expansions would follow a similar process.

The following comments were received from Richard Ozanich, President of Berkeley Instruments, Inc.

1) It is unknown whether sufficient soil analysis is being done to identify the particular chemicals in
contaminated soil. This leads to the following problems.

A) Clean soil may be being removed - taking up valuable and costly ERDF disposal space (I would hope that
environmental restoration progress and performance is not evaluated by the volume of dirt moved).

Response: Sampling of waste sites is done prior to excavation in order to determine contaminants of concern.
Field screening during excavation is done to better define the area between clean and contaminated soil and
to verify the waste profile.

B) Soil with different contaminants present may be mixed. While various chemical reactions are possible,
the most potentially concerning is the mixing of complexant containing soil (e.g., EDTA - tons used at
Hanford) with toxic species such as heavy metals or radionuclides (e.g., Pu), thus dramatically
increasing the mobility of these otherwise immobile toxic species.

Response: Reactivity is evaluated as part of the waste acceptance process for ERDF. Additionally, the
double liner configuration of the facility is such that the leachate is collected during the operational
period. The data collected thus far indicate that little contamination is being released from the material
disposed in the facility.

The following comment was received from Len Clossev, a private citizen.

I believe ERDF is a great step forward in the safe disposal of radioactive (dry) waste. I therefore
recommend that two more cells for the ERDF Site be approved for construction, providing a safe storage
facility thus minimizing adverse impacts to the environment.

DOE, Bechtel, and the Regulatory Agencies should be congratulated for the way this program was designed and
in the way it is being carried out.

Response: Thank you for your comment.
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