EPA/ESD/R10-98/062
1998
EPA Superfund
Explanation of Significant Differences:
IDAHO NATIONAL ENGINEERING LABORATORY
(USDOE)
EPA ID: ID4890008952
OU18
IDAHO FALLS, ID
09/01/1998
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EPA 541-R98-062
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Explanation of Significant Differences for the
Pit 9 Interim Action Record of Decision
at the Radioactive Waste Management Complex
at the Idaho National Engineering and Environmental Laboratory
Idaho Falls, Idaho
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Explanation of Significant Differences for the Pit 9 interim Action
Record of Decision at the Radioactive Waste Management
Complex
Idaho National Engineering and Environmental Laboratory
I. Introduction
This document is an Explanation of Significant Differences (BSD) from the Record of Decision (ROD) for the
Pit 9 Interim Action, signed by the United States Department of Energy, United States Environmental
Protection Agency, and State of Idaho Department of Health and Welfare (the Agencies), effective October 1,
1993, in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)
as amended by the Superfund Amendments and Reauthorization Act, and to the extent practicable, the National
Oil and Hazardous Substance Pollution Contingency Plan. This BSD is also prepared in accordance with the
terms of the INEEL Federal Facility Agreement and Consent Order.
Site Name and Location
Pit 9, Subsurface Disposal Area, Radioactive Waste Management Complex
Waste Area Group 7, Operable Unit 7-10
Idaho National Engineering and Environmental Laboratory (INEEL)
The lead agency for this action is the United States Department of Energy Idaho Operations Office (DOE-ID).
The United States Environmental Protection Agency and the State of Idaho Department of Health and Welfare
(IDHW) both concur with, and approve the need for, this significant change to the selected remedy. The
Agencies participated jointly in preparing this document.
Need and Purpose for an Explanation of Significant Differences
This BSD was prepared in accordance with Section 117 (c) of the CERCLA, and 40 CFR 300.435(c) (2) (i) which
reguires that an BSD be published "when the differences in the remedial or enforcement action, settlement, or
consent decree significantly change but do not fundamentally alter the remedy selected in the ROD with
respect to scope, performance, or cost."
Accordingly, this explanation addresses the fact that the INEEL management and operating contractor (LMITCO)
has terminated the subcontract to the Pit 9 remediation contractor (LMAES) for default, and DOE has adopted a
contingency plan that will allow the DOE to meet its obligations for the remediation of Pit 9, without the
participation of the subcontractor. This and other relevant documents will become part of the Administrative
Record file pursuant to 40 CFR 300.825(a)(2).
Copies of this BSD and the Pit 9 Administrative Record are available to the public in the INEEL Information
Repository sections of the libraries and offices listed on the last page of this Explanation of Significant
Differences.
II. Site History and Contamination Problems
The INEEL is located 32 miles west of Idaho Falls in southeastern Idaho and encompasses approximately 890
sguare miles of semi-arid desert overlying the Snake River Plain Aguifer. The Subsurface Disposal Area is
located at the Radioactive Waste Management Complex, which is located in the southwest portion of INEEL. The
area of focus is Pit 9, which is located in the northeast corner of the Subsurface Disposal Area. Pit 9 is
designated as Operable Unit 7-10 and is scheduled as an interim action in the Action Plan of the Federal
Facility Agreement and Consent Order.
Pit 9 was operated as a waste disposal pit from November 1967 to June 1969. It was used to dispose of
approximately 110,000 cubic feet (3,115 cubic meters) of transuranic waste (as defined in 1969, > 10 nCi/g)
from the Rocky Flats Plant and additional low-level wastes (as defined in 1969, < 10 nCi/g) from waste
generators located at the INEEL, for a total estimated waste volume of 150,000 cubic feet (4,248 cubic
meters).The estimated volume of overburden is approximately 250,000 cubic feet (7,079 cubic meters). The
estimated volume of soil between and below the buried waste is approximately 350,000 cubic feet (9,911 cubic
meters). Most of the transuranic waste consists of drums of sludges (contaminated with a mixture of
transuranic waste and organic solvents), drums of assorted solid waste, and cardboard boxes containing empty
contaminated drums.
III. DESCRIPTION OF SIGNIFICANT DIFFERENCES AND BASIS
The significant change that necessitated this BSD relates to the change in subcontractor and implementation
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of a contingency path to remediate Pit 9. Although this contingency path does not involve a change in the
selected remedy type (i.e., physical separation/chemical extraction/stabilization), it does involve a change
in design and operating assumptions.
This contingency path became necessary when the original subcontractor failed to perform its obligations
under the subcontract in a timely manner. DOE did not meet two enforceable regulatory milestones, and in
March 1997, the Agencies developed an Agreement to Resolve Disputes). 1
The DOE remains committed to executing the terms of the Pit 9 Record of Decision. As a result of the
Agreement to resolve Disputes, DOE developed a revised Remedial Design/Remedial Action Scope of Work and
Remedial Design Work Plan. 2 The revised Work Plan included a new schedule for implementation of the Pit 9 is
ROD by the subcontractor, and a schedule for a contingency path, which would be implemented in the event the
subcontractor failed to perform their subcontract. The DOE-ID, the EPA and the IDHW jointly developed this
contingency plan. The Agencies agreed to proceed with the contingency planning in order to ensure future
schedules would be met. In addition, there was a need to obtain information to support the Waste Area Group 7
decision process, including characterization and treatability information.
On June 1, 1998 the INEEL management and operating contractor (LMITCO) terminated the Pit 9 LMAES subcontract
for default. Therefore, on June 18, 1998, DOE decided to pursue the contingency path, hereafter referred to
as the OU 7-10 Staged Interim Action, described below. The OU 7-10 Staged Interim Action will remediate Pit 9
in accordance with the ROD.
OU 7-10 Staged Interim Action
The OU 7-10 Staged Interim Action, a three-stage approach agreed to by the Agencies, will satisfy the
reguirements of the ROD. The OU 7-10 Staged Interim Action, as the original subcontractor's approach, will
result in the remediation of Pit 9. The OU 7-10 Staged Interim Action, like the original Pit 9 approach, is
also designed to generate information to support the Remedial Investigation and Feasibility Study for the
RWMC SDA.
Stage I activities will explore the subsurface via probe holes and coring, providing early information in the
Stage II area of Pit 9. Stage II activities include design, construction, and retrieval of waste and soils
from a 20'X20'X25' area of Pit 9. Characterization and treatability information obtained from Stage II is
expected to support the WAG 7 decision. Stage III will complete the remediation of Pit 9.
The Agencies are aware of the amended rules under the Toxic Substance Control Act (Federal Register Volume
63, Number 124, Monday, June 28 1998, 35384, Disposal of Polychlorinated Biphenyls) effective August 28,1998
and have agreed to comply with the provisions under this rule in implementing the OU 7-10 Staged Interim
Action.
Stage I
Stage I will focus on subsurface exploration to (1) more precisely determine the location of the Stage II
excavation, (2) retrieve TRU radionuclide contaminated soil via drill cores for the Stage 1 Treatability
Studies, and (3) obtain materials for characterization in support of the overall WAG 7 decision process.
Specific details of the Stage I scope are available in the Work Plan for Stage I of the Pit 9 Contingency
Project.3
Several different types of subsurface exploration methods will be implemented to meet the objectives of this
work. A sonic vibratory drill will be used to core the waste site without introducing any drilling fluids.
Monitoring activities will also be performed in conjunction with the subsurface exploration. This will be
accomplished through radiological profiling, volatile organic profiling, and other technigues.
An objective for obtaining subsurface materials from Pit 9 is to provide information to support the WAG 7
decision process. The Stage I efforts Linder the contingency path will obtain data couceming waste form,
contaminant migration, actinide speciation, volatile organic content of specific sludges, etc. Stage I will
also perform benchscale treatability study tests on TRU contaminated soil samples to test various soil
treatment technologies that could be employed in Stage III.
1 "Agreement to Resolve Disputes," Docket No. 1088-06-29-120, March 18,1997.
2 "Remedial Design/Remedial Action Scope of Work and Remedial Design Work Plan: Operable Unit 7-10 (Pit 9
Project Interim Action), "October 1997, Revision 2, Document # INEL-94/0110.
3 "Work Plan for Stage 1 of the Pit 9 Contingency Project," June 1998, INEEL/EXT-98-10623.
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Stage II
Under the OU 7-10 Staged Interim Action, approximately 200 cubic yards (equivalent to about nine hundred 55-
gallon drums) of contaminated waste and soil is expected to be removed during the Stage II excavation. Stage
II will consist of design and construction, startup activities, excavation and retrieval, characterization,
and treatability study testing. Retrieved materials that are not returned to the pit as part of Stage II will
be containerized and staged for further sampling within the area of contamination (AOC) pending final
disposition.
The goal of the Stage II excavation is to develop information to support the design and operation of a Stage
III system that will meet the requirements established in the Pit 9 ROD.
Stage III
Stage III consists of full-scale retrieval and treatment of Pit 9 to meet remediation goals set in the ROD.
Treatment technologies utilized will include chemical extraction and physical separation and stabilization of
selected waste streams.
Schedule
The INEEL Federal Facility Agreement and Consent Order and Action Plan governs the remediation work performed
at the INEEL, and was signed by all three agencies in December 1991. Under the terms of this agreement,
certain milestones were established, and others can be established, which the DOE must meet. Failure to meet
these milestones subjects the DOE to enforcement actions including fines and penalties. The milestones shown
in table 2 were established in the Remedial Design/Remedial Action Scope of Work and the Work Plan for Stage
1 of the Pit 9 Contingency Project, and are enforceable.
Table 2. OU 7-10 Staged Interim Action Schedule
Milestone Date
Stage I Work Plan March 1998
Stage II RD/RA Work Plan June 2000
Stage II RA Report April 2003
Stage III RD Work Plan (90% Design) April 2003
Stage III RA Work Plan and O&M Plan September 2003
Stage III Draft Remedial Action Report Within 60 Days of Final Stage III Inspection
Stage III O&M Report 90 Days of Stage III O&M Activities
Cost
A Rough Order of Magnitude (ROM) cost for the first two stages of the contingency path is presented in Table
3. This cost is based on an analysis of the pre-conceptual design performed to estimate cost and schedule. As
the work plans for each stage are developed, a cost estimate will be developed. In accordance with RI/FS
guidance, the dollars presented are order-of-magnitude cost estimates. The costs presented are in FY-97
dollars.
Table 3. Cost estimate for Stages I and II.
Estimated Cost
Operations and Maintenance 25M
Capital 61M
Present Worth 86M
Because the details of Stage III will be based on the results of work in Stages I and II, a cost estimate for
Stage III is not presented at this time. As the details of Stage III are developed, one of the goals will be
to complete the overall project within the estimate presented in the 1995 BSD to the Pit 9 ROD.4
4 "Explanation of Significant Differences for the Pit 9 Interim Action Record of Decision at the
Radioactive Waste Management Complex, Idaho National Engineering laboratory," January 1995,
Administrative Record # AR5.3-5862.
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IV. AFFIRMATION OF THE STATUTORY DETERMINATION
Although there are uncertainties in the detailed implementation of the OU 7-10 Staged Interim Action that may
reguire future re-evaluation of the Affirmation of the Statutory Determination, currently available
information does not alter the remedy selected in the ROD. As presented in the ROD, the selected alternative
provides adeguate overall protection of human health and the environment by minimizing potential contaminant
migration from Pit 9. The selected alternative also complies with the Applicable or Relevant and Appropriate
Reguirements of Federal and State laws and regulations as identified in the ROD. Even with the project cost
increases, which were identified in the 1995 BSD, the selected remedy was affirmed to provide the best
balance of trade-offs in terms of long-term effectiveness, reducing toxicity, mobility and volume of the
contaminants, implementability, short-term effectiveness, and cost. The issues presented in this BSD do not
alter the beneficial attributes of the selected remedy and its ability to achieve the remedial action
objectives established in the ROD.
Considering the change to the project schedule and the development of a contingency plan (referred to as the
OU 7-10 Staged Interim Action), the DOE, EPA and IDHW believe that the modified remedy remains protective of
human health and the environment and complies with Federal and State reguirements that are applicable or
relevant and appropriate to this remedial action, and is cost-effective. In addition, the selected remedy
meets the statutory reguirements to use permanent solutions and treatment technologies to the maximum extent
possible. The Agencies prefer a potential permanent solution whenever possible and, in the case of Pit 9, the
goal is to meet the objectives of an interim action and provide a potentially permanent treatment solution.
V. PUBLIC PARTICIPATION ACTIVITIES
A notice publishing the availability of this BSD has been placed in the Post Register - Idaho Falls, Idaho
State Journal - Pocatello, Times-News - Twin Falls, Idaho Statesman - Boise, Sho-Ban News - Fort Hall, and
Daily News - Moscow. Consistent with Section 300.435 (c) (2) (i) of the National Contingency Plan, this BSD has
been placed in the Administrative Record Section of the INEEL Information Repositories listed below upon
publication of the Notice of Availability. A postcard announcing the availability of this BSD was sent to the
INEEL mailing list participants. This BSD and the contents of the Pit 9 Administrative Record are available
for public review. In addition to the Administrative Record on file for the ROD, the Administrative Record
for this action includes a copy of this BSD and relevant newspaper notices associated with the explanation
(refer to the binder for OU 7-10) .
The revised schedule and the implementation of the contingency path do not represent a fundamental change
from that contained in the ROD, and therefore, a formal comment period is not reguired. Additional
information or briefings may be reguested by contacting the office listed below or calling the toll-free
number for the INEEL at (800) 708-2680:
Erik Simpson
INEEL Community Relations Plan Office
P.O. Box 2047
Idaho Falls, Idaho 83403-2047
(208) 526-4700
LIBRARIES AND OFFICES CONTAINING INFORMATION REPOSITORIES
DOE Reading Room
INEEL Technical Library
1776 Science Center Drive
Idaho Falls, Idaho
University of Idaho Library
U of I Campus
Moscow, Idaho
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