United States
Environmental Protection
Agency
&EPA
Office of Air and Radiation
Office of Solid Waste and
Emergency Response
Washington, DC 20460
EPA402-R-96-017
November 1996
Technology Screening
Guide for Radioactively
Contaminated Sites
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EPA402-R-96-017
November 1996
TECHNOLOGY SCREENING GUIDE FOR
RADIOACTIVELY CONTAMINATED SITES
Prepared for
U.S. Environmental Protection Agency
Office of Air and Radiation
Office of Radiation and Indoor Air
Radiation Protection Division
Center for Remediation Technology and Tools
and
U. S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Prepared Under:
Contract No.
68-D2-0156
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Preceeding Page Blank
DISCLAIMER
Mention of trade names, products, or services does not convey, and should not be interpreted
as conveying, official EPA approval, endorsement, or recommendation.
in
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ACKNOWEDGEMENTS
Edward Feltcorn of ORIA's Center for Remediation Technology and Tools was the EPA
Work Assignment Manager for this guide. Assistance in production of this guide was
provided by Jack Faucett Associates (Barry Riordan - Project Manager) under EPA Contract
Number 68-D2-0156.
EPA/ORIA wishes to thank the following individuals for their assistance and technical review
comments on the drafts of this report:
Doug Bell, EPA/ Superfund
Dr. Walter Kovalick, Jr., EPA Technology Innovation Office
Paul Giardina, EPA Region 2
Paul Leonard, EPA Region 3
Nancy Morlock, EPA Region 6
Linda Meyer, EPA Region 10
Ed Earth, EPA/ORD Cincinnati
Gregg Dempsey, EPA/ORIA Las Vegas Facility
Sam Windham and Samuel Keith, EPA/ORIA NAREL
EPA/ORIA would like to extend special appreciation to Thomas Sorg of EPA/ORD
Cincinnati, without his assistance the section on liquid media would have not been complete.
In addition, the following staff from ORIA's Remediation Technology and Tools Center
assisted in the development, production and review of this document:
Nick Lailas, Director
Ron Wilhelm
Tri Hoang
Carey Johnston
IV
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TO COMMENT ON THIS GUIDE OR PROVIDE INFORMATION FOR FUTURE
UPDATES:
Send all comments/updates to:
US Environmental Protection Agency
Attention: Technology Screening Guide for Rad
Contaminated Sites
401MStSW(6602J)
Washington, DC 20460
or
Ed Feltcorn
Email: Feltcorn.Ed@EPAMail.EPA.GOV
Tel: 202-233-9350 Fax: 202-233-9650
v
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Preceeding Page Blank
TABLE OF CONTENTS
J
PAGE
LIST OF ACRONYMS
EXECUTIVE SUMMARY
SECTION I: INTRODUCTION
1.1 Purpose
1.2 Background
1.3 General Information Related to Radioactively Contaminated NPL Sites 4
1.3.1 Types of Sites 4
1.3.2 Characteristics of Radioactively Contaminated NPL Sites 4
1.3.3 General Remedial Response Actions 8
1.4 Technical Approach Used 9
1.4.1 Technologies Presented 9
1.4.2 Approach to Evaluating Technologies 10
1.4.3 Summary of Selected Technologies 12
1.5 Organization of this Guide 19
SECTION II: SOLID MEDIATECHNOLOGY PROFILES 23
Containment 25
2.1 Capping 27
2.2 Land Encapsulation 35
2.3 Cryogenic Barriers 43
2.4 Vertical Barriers 51
Solidification/Stabilization 61
2.5 Cement Solidification/Stabilization 63
2.6 Chemical Solidification/Stabilization 71
Chemical Separation 79
2.7 Solvent/Chemical Extraction 81
Physical Separation 89
2.8 Dry SoiI Separation 91
2.9 Soil Washing 99
2.10 Flotation 109
Vitrification 119
2.11 /n-s/tu Vitrification 121
2.12 Ex-situ Vitrification 129
vn
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TABLE OF CONTENTS
(continued)
PAGE
SECTION III: LIQUID MEDIATECHNOLOGY PROFILES 137
Chemical Separation 139
3.1 Ion Exchange & Chemical Precipitation 141
Physical Separation 151
3.2 Membrane Processes, Carbon Adsorption, and Aeration 153
APPENDIX A: Radioactive Contamination: Basic Concepts and Terms A-l
APPENDIX B: Bibliography B-l
Vlll
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LIST OF EXHIBITS
PAGE
Exhibit ES-1: Demonstrated Remediation Technologies for Prevalent Radionuclides at Radioactively
Contaminated Sites xv
Exhibit 1-1: Isotope Distribution at Radioactively Contaminated NPL Sites 5
Exhibit 1-2: NPL Sites by Media Contaminants 5
Exhibit 1 -3: NPL Sites and Radionuclides Detected 6
Exhibit 1-4: NCP Evaluation Criteria Included in Technology Profiles 11
Exhibit 1-5: Summary of Solid and Liquid Media Technologies 13
Exhibit 1-6: Solid Media Technology Categories 20
Exhibit 1-7: Using the Technology Profiles 21
Exhibit 2-1: Capping Diagram 28
Exhibit 2-2: Technical Characteristics Of Capping 29
Exhibit 2-3: NCP Criteria For Capping 33
Exhibit 2-4: Land Encapsulation Diagram 36
Exhibit 2-5: Technical Characteristics Of Land Encapsulation 37
Exhibit 2-6: NCP Criteria For Land Encapsulation 41
Exhibit 2-7: Cryogenic Barriers Diagram 44
Exhibit 2-8: Technical Characteristics of Cryogenic Barriers 45
Exhibit 2-9: NCP Criteria for Cryogenic Barriers 49
Exhibit 2-10: Vertical Barriers Diagram 53
Exhibit 2-11: Technical Characteristics of Vertical Barriers 53
Exhibit 2-12: NCP Criteria for Vertical Barriers 58
Exhibit 2-13: Ex-Situ Solidification/Stabilization 62
Exhibit 2-14: In-Situ Solidification/Stabilization 62
Exhibit 2-15: Technical Characteristics of Cement Solidification/Stabilization 64
Exhibit 2-16: NCP Criteria for Cement Solidification/Stabilization 69
Exhibit 2-17: Technical Characteristics of Chemical Stabilization/Solidification 72
Exhibit 2-18: NCP Criteria for Chemical Stabilization/Solidification 76
Exhibit 2-19: Solvent Extraction Diagram 82
Exhibit 2-20: Technical Characteristics of Solvent/Chemical Extraction 83
Exhibit 2-21: NCP Criteria for Solvent/Chemical Extraction 88
Exhibit 2-22: Dry Soil Separation Diagram 91
Exhibit 2-23: Technical Characteristics of Dry Soil Separation 92
Exhibit 2-24: NCP Criteria for Dry Soil Separation 96
Exhibit 2-25: Soil Washing Diagram 98
Exhibit 2-26: Technical Characteristics of Soil Washing 99
Exhibit 2-27: NCP Criteria for Soil Washing 106
Exhibit 2-28: Flotation Diagram 109
Exhibit 2-29: Technical Characteristics of Flotation 110
Exhibit 2-30: NCP Criteria for Flotation 114
Exhibit 2-31: In-situ Vitrification Diagram 119
Exhibit 2-32: Technical Characteristics of In-situ Vitrification 120
Exhibit 2-33: NCP Criteria for In-situ Vitrification 124
Exhibit 2-34: Ex-Situ Vitrification Diagram 128
Exhibit 2-35: Technical Characteristics of Ex-Situ Vitrification 129
Exhibit 2-36: NCP Criteria for Ex-Situ Vitrification 134
IX
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LIST OF EXHIBITS
(continued)
PAGE
Exhibit 3-1 Ion Exchange Diagram 142
Exhibit 3-2 Chemical Precipitation Diagram 143
Exhibit 3-3 NCP Criteria for Chemical Separation 147
Exhibit 3-4 Microfiltration Diagram 154
Exhibit 3-5 Carbon Adsorption Diagram 155
Exhibit 3-6 NCP Criteria for Physical Separation 160
Exhibit A-l Categories of Radioactive Materials A-2
Exhibit A-2 Statutory and Regulatory Categories of Radioactive Waste A-4
Exhibit A-3 Progressive Decay of a Radioactive Isotope A-5
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LIST OF ACRONYMS
AMU Atomic Mass Unit
ARAR Applicable or Relevant and Appropriate Requirements
CAA Clean Air Act
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act (Superfund)
CFR Code of Federal Register
CWA Clean Water Act
DOD Department of Defense
DOE Department of Energy
DRE Destruction and Removal Efficiencies
EDTA Ethylenediamine-tetraacetic acid
EP Extraction Procedure
GAC Granular, Activated Carbon
HOPE High Density Polyethylene
ISV In-situ Vitrification
LDR Land Disposal Restrictions
LLRWPAA Low-level Radioactive Waste Policy Amendments Act of 1985
LLW Low-level Waste
MCL Maximum Concentration Level
MR Millirem
NCP National Contingency Plan
NPDES National Pollutant Discharge Elimination System
NPL National Priorities List
NRC U.S. Nuclear Regulatory Commission
NTIS National Technical Information Service
O&M Operations and Maintenance
ORIA Office of Radiation and Indoor Air
ORNL Oak Ridge National Laboratory
RCRA Resource Conservation and Recovery Act
RI/FS Remedial Investigation/Feasibility Study
ROD Record of Decision
S/S Solidification/Stabilization
SVOC Semivolatile Organic Compound
TCLP EPA Toxicity Characteristic Leaching Procedure
TRU Transuranic Waste
VOC Volatile Organic Compound
XI
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Preceeding Page Blank
EXECUTIVE SUMMARY
J
The U.S. Environmental Protection Agency (EPA), Office of Radiation and Indoor
Air, Radiation Protection Division's Center for Remediation Technology and Tools, produced
this Technology Screening Guide for Radioactively Contaminated Sites (Guide) to help
identify and screen technologies that may effectively treat radioactively contaminated sites.
The Guide is designed to give easy access to critical information on applied technologies that
address radioactive contamination in solid and liquid media. The solid media includes soils,
sediment, sludge, and solid waste, but does not include buildings and structures. The liquid
media include groundwater, surface water, and waste water. This information is presented in
technology profiles that can be used to screen and compare technologies for site-specific
application.
The profiles include 17 applied technologies (technologies in use at contaminated
sites) viable for response actions at such sites. There are 12 technologies associated with
contaminated solid media and are grouped into five categories: containment,
solidification/stabilization, chemical separation, physical separation, and vitrification. There
are 5 technologies associated with contaminated liquid media and are grouped into two
categories: chemical separation and physical separation.
This Guide builds on significant efforts by EPA, the Department of Energy, the
Department of Defense, and other agencies to facilitate remedy selection. This Guide also
updates information on each technology's operating and performance data. This Guide has
been distributed as a draft document to a large and diverse group of peer reviewers, whose
comments have been addressed in this final version of the Guide.
Profiles for each technology include a basic description, contaminants addressed,
technology operating characteristics, and site characteristics that affect performance. Each
profile describes how the technology has performed against the following seven of the nine
National Contingency Plan (NCP) evaluation criteria:
protection of human health and the environment;
compliance with applicable or relevant and appropriate requirements
(ARARs);
long-term effectiveness;
reduction of toxicity, mobility, or volume through treatment;
short-term effectiveness;
implementability; and
cost.
Xlll
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The state and community acceptance NCP criteria are not addressed in the profiles
because the assessments of the remedial technologies against these criteria usually are site-
specific. Finally, the profiles summarize the key information for each technology.
Section I introduces the Guide and provides background information on general
characteristics of radioactive waste at NPL sites. Section II provides profiles for technologies
applicable to solid media while section III presents profiles for technologies applicable to
liquid media. A quick reference to radiation concepts and glossary of terms is provided in
Appendix A. The Bibliography in Appendix B cites general references and categorizes
references by technologies. Exhibit ES-1, provides a summary of the information in this
Guide, concerning the technologies that have been demonstrated to be applicable to the most
commonly found radionuclides at Superfund sites, in three broad classes of media.
xiv
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SECTION I
INTRODUCTION
1.1 PURPOSE
This Guide is designed to help site managers identify and screen technologies that are
potentially effective in cleaning up radioactively contaminated sites. EPA recognizes that site
managers fulfill numerous technical, management, and regulatory responsibilities, all driven
by the goal of making expedient yet careful decisions about site response actions. While
these responsibilities are met at all Superfund and RCRA Corrective Action sites, they are
particularly challenging when site managers must deal with the complexity of radioactive
contamination.
To make appropriate site response action decisions, site managers must have the
pertinent technical information to help guide them. This document is a reference that can be
consulted for critical information on radioactive contamination cleanup technologies to screen
applications at their site. This Guide updates information from previous EPA publications on
applied technologies for solid and liquid media contamination. Each technology profile is
presented in two parts. The first part provides process descriptions, operating principles, and
other features in a consistent presentation format for each technology. The second part
provides an evaluation of this data against the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP) evaluation criteria.1
The Guide has been written for site managers who have had some Superfund or RCRA
experience, although not necessarily with radioactive contamination. In planning and
implementing response actions, this document can be used in the Remedial Investigation/
Feasibility Study (RI/FS) Proposed Plan, or Corrective Measures Study (CMS) processes. In
National Oil and Hazardous Substance Pollution Contingency Plan, 40 CFR Part 300, March 8, 1990, contains the implementing
regulations for CERCLA, including the methodology for assessing the range of remedial technologies.
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addition, Superfund and RCRA program administrators, EPA site manager counterparts in
federal facilities, site managers outside of EPA, EPA Regional Radiation Program staff and
technology vendors can use the Guide to evaluate technology options.
1.2 BACKGROUND
Since the passage of CERCLA in 1980, significant efforts have been made to study,
develop, and use technologies that can address radioactive contamination. Diverse initiatives
have attempted to pinpoint the safest, most thorough, efficient, and cost-effective ways to
respond to this type of hazard. The American Nuclear Society, the Commission of the
European Communities, and the International Atomic Energy Agency, for example, have
examined remediation and waste management options for low-level and high-level
radioactive waste in the United States and abroad.2 In addition, the Department of Energy
(DOE) has played a major role in researching potential applications for innovative
technologies at Federal Facility Superfund sites.3 The Department of Defense (DOD) has
also helped refine the search for applicable technologies in its work on nonradioactive waste.4
EPA had previously compiled information on cleanup technologies for radioactive
waste in two documents described below.
Technological Approaches to the Cleanup of Radiologically Contaminated
Superfund Sites(1988) discusses remediation technologies for soils
contaminated by radioactivity. It identifies the full range of technologies
potentially useful in reducing radioactivity levels at hazardous waste sites,
describing the technology, its development status, potential application,
advantages and disadvantages, and associated information needs.
Assessment of Technologies for the Remediation of Radioactively
Contaminated Superfund Sites(1990) rated technologies by examining 29
technologies for cleaning up soil, water, and structures. It also identified
information gaps related to assessing the technologies.
Despite EPA and other agencies' efforts, information on radioactive cleanup
technologies is scattered; site managers under pressure to make decisions must often sift
Appendix B, the Bibliography, presents multiple listings of conference proceedings from these organizations.
Readers can consult DOE findings on technology innovations in several sources noted in the bibliography or specific technology profiles in
this document. Technical information is available in two key resources. The DOE Environmental Restoration and Waste Management (EM),
Office of Technology Development's armualTechnology C atalogueprovides descriptions of the technology and its technical performance,
projected performance, waste applicability, status, regulatory considerations, potential commercial applications, baseline technology, and
intellectual property rights of site characterization and monitoring, site remediation, and waste management technologies. In addition, the 1993
Oak Ridge National Laboratory (OKN~L)Technology Logic Diagram, Volume 3 Technology Evaluation Data Sheetsites the following key
information on 127 Remedial Action technologies: the ORNL problem to be addressed, problem area/constituents, reference requirements, sub-
elements, technology, status, science/technology needs, and implementation needs.
DOD Environmental Technology Transfer Committee, EPA, Dept. of Interior and Dept. Of Energy cooperatively prepared in 1994 the
Remediation Technologies Screening Matrix and Reference Guidef/hich helps site managers narrow the field of remediation alternatives in the
remedy selection process.
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through volumes of information, a time-consuming process. Recognizing the ongoing
challenge of integrating vast quantities and levels of information into one resource, this
document:
Builds upon EPA's earlier efforts;
Capitalizes on the work of other researchers; and
Attempts to bridge the body of technology data and the remedy selection
process.
This Guide focuses on technologies that address radioactive waste and are effective for
soil and liquid media at radioactively contaminated sites. The solid media includes soils,
sediment, sludge, and solid waste; it does not include buildings and structures. The liquid
media include groundwater, surface water, and waste water. It does not address radon in air
or the decontamination of structures. Sufficient information is provided to screen these
technologies for a possible match to the specific site of interest to the user.
To develop this document, a survey of EPA and DOE databases such as VISITT and
ER 95 was performed, and documents were reviewed that describe or assess technology
applications to radioactively contaminated waste. This information was drawn from
government publications and journal articles and formed the basis for the technology
characterizations presented in subsequent sections. Also reviewed were CERCLA Records of
Decision (RODs) for NPL sites contaminated with radioactive waste. The RODs provided
some additional insight into the remedy selection process at Superfund sites with radioactive
contamination. They also provided a set of technologies that have been considered or
selected for actual cleanup situations using the process required by CERCLA and the NCP.
Finally, this Guide was distributed nationally for peer review and comment.
Additional technical research was conducted to address these comments and to update the
information with other relevant data sources.
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1.3 GENERAL INFORMATION RELATED TO RADIO ACTIVELY
CONTAMINATED SITES
1.3.1 Types of Sites
Of the radioactively contaminated sites identified, nine general types of sites have
been established. These are:5
defense plants
mill tailings, processing, and disposal sites
radium and thorium sites
commercial landfills
low-level waste disposal sites
research facilities
commercial manufacturing
fuel fabrication and processing
scrap metal recovery.
1.3.2 Characteristics of Radioactively Contaminated NPL Sites
Experience with Superfund sites demonstrates that waste at radioactively contaminated
sites are primarily by-products of four main processes or activities: research, design, or
development of nuclear weapons; radioactive waste disposal; mining/processing of
radioactive ores; and some forms of manufacturing. As shown in Exhibit 1-1, uranium
represents the most prevalent element with respect to radioactively contaminated NPL sites,
followed by radium, radon, and thorium.
US EPA (l993),Environmental Characteristics of EPA, NRC, and DOE Sites Contaminated with Radioactive Sutstanc$.U.S. EPA,
Air and Radiation, EPA 402-R-93-011, March 1993.
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to
* Other isotopes: Ac-227, Am-241, C-14,
Ce-144, Cm-244, Eu-152/154/155,
1-129/130, Kr-85, Mn-54, Ni-63,
Pa-231, Ru-106, Sb-125, Se-79.
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Exhibit 1-1: Isotope Distribution at Radioactively Contaminated NPL Sites*
*Source: US EPA (1993),Environmental Pathway Models - Groundwater Modeling in Support of Remedial Decision-
Making at Sites Contaminated with Radioactive Materials, EPA 402-R-93-009.
EPA's 1990 study of some radioactively contaminated NPL sites found that most sites
were characterized by "soils contaminated with Radium, Thorium, and/or Uranium" (92%) or
"water contaminated with Radium, Thorium, and/or Uranium" (80%). Exhibit 1-2 illustrates
how the sites in the 1990 study were dispersed with respect to contaminants present and
media affected.
Exhibit 1-2: NPL Sites by Media and Contaminants*
CONTAMINANT || SOILS || WATER || STRUCTURES
Radium/Thorium/Uranium
Other Radionuclides
Mixed Waste
23
6
11
20
5
12
8
2
3
*Source: Assessment of Technologies for the Remediation of Radioactively Contaminated Superfund
Sites, EPA (1990).
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Exhibit 1-3 provides more specific information about the media impacted and
radionuclides detected at the sites.
Exhibit 1-3: NPL Sites and Radionuclides Detected*
SUPERFUND SITE ||| MEDIA IMPACTED ||| RADIONUCLIDES PRESENT
Austin Avenue Radiation Site
Agrico Chemical Co.
Denver Radium Site
Feed Materials Production
Center (DOE)
Glen Ridge Radium Site
Hanford 100-Area (DOE)
Hanford 200-Area (DOE)
Hanford 300-Area (DOE)
Homestake Mining Company
Idaho National Engineering
Lab (DOE)
Kerr-McGee (Kress Creek)
Kerr-McGee (Reed Keppler)
Kerr-McGee (Residential)
Kerr-McGee (Sewage
Treatment Plant )
Lansdowne Radiation Site
Lincoln Park
Lodi Municipal Well
Maxey Flats Nuclear Disposal
Maywood Chemical Co.
Soil, Debris
Groundwater
Soil, Debris, Groundwater,
Air
Debris
Soil
Solid and Liquid Waste,
Groundwater, Surface Water
Solid and Liquid Waste,
Groundwater, Surface Water
Solid and Liquid Waste,
Groundwater, Surface Water
Soil, Tailings, Groundwater,
Air
Sediment, Soil, Solid Waste
Sediment, Soil, Tailings
Groundwater, Soil, Air
Soil, Tailings
Soil, Groundwater
Soil, Sewer Lines, Building
Materials
Groundwater
Groundwater
Soil, Groundwater, Surface
Water, Sediment, Air
Groundwater, Soil, Sediment
Ra-226, Th-230, U-238
U-238, Ra-226, Ra-228, gross alpha,
gross beta
Ra (Soil); U-234, U-238, Th-230, Ra-
226, Rn-222 present
U-238, U-234, U-235, U-238, Th-230,
Th-232, Th-228, Ra-226, Ra-228, Cs-
137
Rn-222 (Gas); Ra-226, U-234, Th (Soil)
U, Pu-238, Pu-239, Pu-240, Cs-137, Sr-
90, Co-60, Ni-63, Eu-152, Eu-154, Eu-
155, Tritium
U, Pu-239, Pu-240, Cs-137, Sr-90, Co-
60, 1-129, Tritium
U, Pu-238, Pu-239, Pu-240, Cs-137, Sr-
90, Co-60, Pr- 147
Rn-222 (Air); Ra (Tailings); U (GW)
Cs-137, Co-60, Strontium, Plutonium,
Uranium, Th-230, Americium
Thorium
Th-232, Ra-226 (GW); Th-232 (Soil)
Th-232
Th-232 (Soil), Th-232, Th-230, Ra-226
(GW)
Ra-226, Th-230, Ac-227 (Soil); Rn-222,
Rn-220, Ra-226, Th-230, Ac-227, Pa-
23 1 (Sewer, Bldg.)
Ra-226, U-234, U-238
U-238
Ra, U, Th, H-3, Cs-137, Co-60 (Soil);
Ra-226, U, H-3, Sr-90, Pu-239 (GW);
Ra-226, H-3 (SW); Ra-226, Sr-90, Pu-
239, Cs-137, H-3 (Sediment); H-3 (Air)
Rn-222 (GW); Th-232, Ra-226, U-238
(Soil); Th-232, Ra-226, U-238
(Sediment)
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Exhibit 1-3: NPL Sites and Radionuclides Detected* (Cont.)
SUPERFUND SITE ||| MEDIA IMPACTED ||| RADIONUCLIDES PRESENT
Montclair Radium Site
Monticello Radioactivity
Contaminated Properties
Oak Ridge Reservation (Lower
Watts Bar Reservoir) (DOE)
Paducah Gaseous Diffusion
Plant (DOE)
Radioactive Waste
Management Complex
Rocky Flats Plant (DOE)
Savannah River Site (DOE)
Schpack Landfill
Teledyne Wah Chang
U.S. Radium Corporation
United Nuclear Corporation
Uravan Uranium
W.R. Grace & Co. Inc. (DOE)
Weldon Spring Quarry (DOE)
Soil
Tailings
Solid Waste, Groundwater,
Sludge, Soil
Liquid waste, Groundwater
Debris
Soil, Sediment, Wastewater
Impoundments
Soil, Sludge, Groundwater
Soil and Groundwater
Sludge, Groundwater
Soil
Groundwater, Surface Water,
Tailings
Groundwater, Air, Tailings,
Surface Water
Soil, Groundwater, Surface
Water, Sediment
Soil, Groundwater, Air,
Sediment (Raffinate Pits)
Ra, Th, U (Soil); Rn-222 (Gas)
U-238, U-236, Ra-226, Th-230, Rn-222,
Ra-226
Cs-137, Co-60, Sr-90, Ra-226, Cm-244,
Th-230, Th-232, Pu-238, Pu-239, U-234,
U-235, U-238
Tc-99, Np-237, Th-230, U-234, U-235,
U-238
Pu-238, Pu-239, Pu-240, Pu-241, Pu-
242, Amencium, Th-232, U-234, U-235,
K-40
Pu, Tritium
Radium, Chromium
Ra-226, U-238, U-234 (Soil); Rn-222
(GW); K-40, Th-228, Th-230 present
Ra-226, Th, U (Sludge); Ra-228 (GW)
Ra-226, U-238
Ra-226, Ra-228, Th-230 (GW); Ra-226,
Ra-228, Th-230, Th-277(SW); U-238,
Th-230, Ra-226, Rn-222 (Tailings)
Rn-222, U-234, U-238, Th-230, Ra-226
Th-232, Ra-226, Ra-228 (Soil, GW, SW,
Sediment); Ra-222, Ra-220
Ra, U, Th (Soil); U (GW, SW); Rn
(Air); Ra-226, Ra-228, U-238, U-234,
U-235, Th-230, Th-232 (Sediment)
*Source: Assessment of Technologies for the Remediation of Radioactively Contaminated Superfund Sites.EPA (1990)
and EPA Records of Decision, Office of Emergency and Remedial Response, through Fiscal Year 1995.
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1.3.3 General Remedial Response Actions
The special characteristics represented by radioactivity in a waste stream constrain the
response options available to site managers. This is because unlike nonradioactive hazardous
waste, which contain chemicals alterable by physical, chemical, or biological processes that
can reduce or destroy the hazard itself, radioactive waste cannot be similarly altered or
destroyed. (For an explanation of the nature and source of radioactive material, refer to
Appendix A.)
Since destruction of radioactivity is not an option, response actions at radioactively
contaminated sites the concepts of "Time, Distance and Shielding" are the concepts used in
radiation protection. Time allows the natural decay of the radionuclide to take place, resulting
in reduction in risk to human health and the environment. Distance and shielding from the
radioactive material rapidly reduces the risk from all forms of radiation by reduction of the
intensity of the imparted energy. Therefore all remediation solutions involve either removing
and disposing of radioactive waste, or immobilizing and isolating radioactive material to
protect human health and the environment. Radioactive material can be extracted from soil
and water and converted to a form for disposal at an approved location. Alternatively,
radioactively contaminated soil can be immobilized, preventing the radioactive components
from migrating from the site and causing harm. Associated with immobilization are measures
to isolate (shield) radioactive material while it decays to site specific levels, thus ensuring that
people are protected from direct exposure to the radiation by inhalation, ingestion or contact.
The selection of response actions is influenced by such considerations as site
characteristics (soil properties, hydrogeology, etc.), the half-life and radiations of the
radioactive material(s) (Alpha, Beta or Gamma), proximity of the waste to populations,
available resources, handling and level of personal protective equipment, and treatment costs.
As part of the selection process, disposal of extracted and concentrated radioactive material
should be considered. Disposal requirements and options for transporting such waste
materials to licensed facilities6 vary, depending on the nature of the contaminant and the
containment technology used.
This Guide presumes that a succession of remedial measures, commonly referred to as
a "treatment train," would be employed at most sites to respond to various types of site
contamination. Treatment trains can reduce the volume of materials that need further
treatment and/or remediate multiple contaminants within a single medium. A treatment train,
for example, might include soil washing, followed by solidification and stabilization
measures, and land encapsulation.
'Commercial sites licensed to receive low-level radioactive waste exist at Barnwell, SC; Hanford, WA; and Beatty, NV. Actions are currently
underway to move the repository operations at Barnwell, SC, to a site in North Carolina.
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1.4 TECHNICAL APPROACH USED
1.4.1 Technologies Presented
To provide a concise guide to a variety of treatment alternatives that may be viable for
response actions at specific sites, 17 applied technologies have been selected for evaluation in
this Guide. These technologies address contamination of solid and liquid media. These were
selected for two reasons: 1) the technology had been considered and/or selected at a
Superfund site with radioactive contamination, or 2) there was sufficient data available from
field scale testing and other research that demonstrated the technology's potential application
to an actual cleanup of radioactive contamination. Many more technologies were reviewed
but not presented due to insufficient data and/or unreliable sources of data. The technologies
in this Guide are:
Solid Media:
- Capping
- Land Encapsulation
Cryogenic Barrier
- Vertical Barriers
Cement Solidification/Stabilization
- Chemical Solidification/Stabilization
Solvent/Chemical Extraction
- Dry Soil Separation
Soil Washing
- Flotation
In-situ Vitrification
Ex-situ Vitrification.
Liquid Media:
Ion Exchange
Chemical Precipitation
Membrane Filtration
Carbon Adsorption
- Aeration.
The determining factor in selecting the technologies presented here is their
applicability to radioactive waste, although they also apply to nonradioactive hazardous
waste. For example, incineration technologies that treat volatile and semivolatile organic
compounds, but which do not affect radioactively contaminated media, are excluded. This
Guide also excludes technologies to specifically remediate radon contamination in air or
contaminated structures. Finally, this Guide addresses waste disposal options only to the
extent of identifying technologies for sites that contain radioactively contaminated media. For
more complete information for supporting site-specific decisions, the bibliography cites
references for readers who wish to explore the technology in greater detail.
-------
1.4.2 Approach To Evaluating Technologies
Profiles of selected technologies are designed to provide pertinent information in a
consistent format. Because numerous information sources are available on these
technologies, only key data concerning technology and site characteristics are included. Data
categories are based on the information useful in evaluating NCP criteria. Each technology
profile addresses the relevant information under three main sections: 1) Technology
Characterization, 2) NCP Criteria Evaluation, and 3) Summary. The following is a detailed
discussion about how profiles are organized and what information they include.
l) Technology Characterization
The technology characterization summarizes current information about the technology
as it has been tested or applied.
Description: This Section describes basic principles and methodologies of
each technology. Descriptions focus on the features relevant to making
criteria evaluations and comparisons with other technologies. Profiles
describe the overall effects of the technology on the contaminated materials
rather than operating procedures, process outcomes, and reagents.
Target Contaminant Groups: This segment of the profile lists individual
contaminants or contaminant groups addressed by the technology.
Technology Operating Characteristics: This segment discusses various
aspects of operating the technology for example, removal efficiencies,
generation of residuals, process times, or high energy demands. The
operating characteristics may influence site managers' decisions about
selecting an appropriate treatment technology.
Site Conditions: This discussion addresses important site conditions that
may affect the technology's viability or implementation at a particular site,
including for example, topography, depth to groundwater, and soil types.
2} NCP Criteria Evaluation
This Section evaluates the technology's performance according to the NCP criteria
established for Superfund sites. Two of the criteria, community acceptance and state
acceptance, are not presented in the profiles, since site managers must evaluate these on a site-
specific basis. Exhibit 1-4 briefly explains the seven remaining evaluation criteria, in relation to
a response action.
10
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Exhibit 1-4: NCR Evaluation Criteria Included in Technology Profiles
Protection of human health and the environment
How the response action will...
through treatment, engineering, controls and/or institutional controls, * provide adequate protection of
human health and the environment by eliminating, reducing, or controlling significant risks posed
through each site-specific pathway
reduce risk exposure levels to protective ARAR levels or to within the EPA-acceptable risk range for
carcinogenic risk or below the Hazard Index of 1 for noncarcinogenic risks
not pose unacceptable short-term risks or cross-media risks.
* Note: Institutional controls alone may not be sufficient response actions for radioactively
contaminated sites.
Compliance with Applicable or Relevant and Appropriate Requirements (ARARs)
Whether and how the response action will comply with all federal ARARs and any more stringent state
ARARs, or if/how the response justified an ARAR waiver.
If no requirements are applicable, then site decision-makers must consider relevant and appropriate
requirements.
Long-term effectiveness and permanence
How the response action will maintain reliable protection of human health and the environment over
time, once cleanup levels have been met.
Reduction oftoxicity, mobility, or volume through treatment
How the treatment will...
address the principal threats at the site, reducing the hazards posed by those threats
destroy, reduce the quantity of, or immobilize contaminants so that they do not leave the site via
exposure pathways
affect toxicity, mobility, or volume reduction with respect to residuals, the risks posed by residuals, and
effects of treatment reversibility.
Short-term effectiveness
Time elapsed until the response action effectively protects human health and the environment.
Prior to attaining cleanup levels, whether any adverse impacts may occur
How/whether the response action will adversely affect the community and workers and impact the
environment during operations.
Implementability
Ease of construction and operation of the response action and availability of services and materials
required to perform the proposed remedial action
Ability to satisfy permitting or administrative requirements for the technology and monitor its
effectiveness, and the availability of necessary equipment, utilities, and operation specialists
Response action's fit with site-specific characteristics
Technical considerations, such as treatment reliability and the possible effect on future remedial action.
11
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Exhibit 1-4: NCR Evaluation Criteria Included in Technology Profiles (Cont.)
Cost
Estimated present worth, capital, and operation and maintenance costs.
NOTE: Costs are typically driven by the cost of purchasing/leasing and operating treatment equipment; the volume
of waste requiring treatment; and costs associated with waste transport, residuals storage and/or disposal. In
addition, for radioactively contaminated sites, costs of remediation could include cost of shielding and protective
equipment from external exposure to remediation workers. Specific cost data are not available for all technologies
and those stated in this Guide should be considered broad estimates.
3) Summary
This Section summarizes the essential information presented in each profile. A matrix
presents a composite view of pertinent performance or site characteristics and how they relate
to the evaluation criteria.
Profiles are designed to enable cross-comparisons with other profiles to screen
technologies for further consideration. To make the final selection from the screened
technology(ies), many site-specific factors, such as hydrogeology and soil porosity, and
factors related to the implementation of each technology, such as materials handling, must be
considered.
1.4.3 Summary of Technologies Selected
A table summarizing each of the technologies is presented in Exhibit 1-5. This table
describes which media are addressed by the technology and the radioactive contaminants for
which the technology is applicable or demonstrated. In addition, the Table includes special
considerations that may affect whether a technology is appropriate for a specific site and
general results and/or limitations on how well the technology has performed.
12
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Exhibit 1-5: Summary of Solid and Liquid Media Technologies
TECHNOLOGY CONTAMINANT
MEDIUM
CONSIDERATIONS
Containment
Capping
(In-situ process)
Applicable for all classes
of radioactive waste
Soils, mine tailings,
sediments, bulk
waste
Inappropriate where water
table is high
Maintenance requires
ensuring against
development, surface
erosion, vegetative growth,
and wildlife activity in cap
area
Reduces vertical but not
horizontal mobility
Does not remove or
remediate contaminated
media
Land Encapsulation
(Ex-situ process)
Applicable for low-level,
mixed and commercial
radioactive wastes
Soil, sediment,
bulk waste
Stringent siting and
construction requirements
Transportation risks exist for
offsite facilities
Does not remediate
contaminated media
Cryogenic Barrier
(In-situ process)
Applicable to all classes
of radioactive waste
Soils, sediment,
bulk waste,
groundwater
Optimal soil moisture must
be maintained
Refrigeration unit must
continue to operate
Remote sites may require
electrical power and utility
installation
Heat from high-level
radioactive waste may
increase electrical power
needs and maintenance costs
Does not remove or
remediate contaminated
media
13
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Exhibit 1-5: Summary of Solid and Liquid Media Technologies (Cont.)
TECHNOLOGY CONTAMINANT
MEDIUM
Solidification/Stabilization
Cement Solidification/
Stabilization
(In-situ or ex-situ
process)
Applicable to all classes
of radioactive waste
Soils, buried waste
CONSIDERATIONS
The chemical form or the
presence of other
contaminants may inhibit
cementation
Best suited to highly
porous, coarse-grained
low-level radioactive
waste in impermeable
matrices
Not suitable if masses are
thin, discontinuous, and
at or near the surface
Debris may interfere with
solidification process
Does not remediate
contaminated media
Chemical
Stabilization/
Solidification
(In-situ or ex-situ
process)
Applicable to all classes
of radioactive waste
Soils, sediments,
sludges
Better suited to fine-
grained soil with small
pores
Presence of some
contaminants may inhibit
chemical effectiveness
Does not remediate
contaminated media
14
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Exhibit 1-5: Summary of Solid and Liquid Media Technologies (Cont.)
TECHNOLOGY
CONTAMINANT
MEDIUM
CONSIDERATIONS
Chemical Separation
Solvent/Chemical
Extraction
(Ex-situ process)
Demonstrated on various
radionuclides
including radium,
thorim, and uranium.
Also, radioisotopes of
cobalt, iron,
chromium, uranium,
and plutonium.
Soils, sediment,
sludge
Ex-situ processes that
require disposal of
separated waste and some
residuals in medium
Multiple reagents may be
used for mixed
contaminants; careful
treatability studies
required
Radioactive contaminant
removal ranges from 13%
to 100% depending on
the contaminant, solvent
type, and conditions
Not practical for soil with
more than 6.7% organic
material
Ion Exchange
(Ex-situ process)
Demonstrated for
radium, uranium and
strontium
Groundwater,
surface water,
wastewater,
liquid waste
Most effective when the
waste stream is in ionic
form
The presence of more
than one radioactive
contaminant may require
more than one treatment
process
Pretreatment may be
necessary for removing
solids, modifying pH, or
removing competing ions
Reported removal rates
for radium and uranium
are 65 to 97% and 65 to
99%, respectively
15
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Exhibit 1-5: Summary of Solid and Liquid Media Technologies (Cont.)
TECHNOLOGY
CONTAMINANT
MEDIUM
CONSIDERATIONS
Chemical
Precipitation
Demonstrated for
uranium
Groundwater,
surface water,
wastewater,
liquid waste
Physical Separation
Dry Soil
Separation
Demonstrated for
thorium, uranium, Pu-
239, Am-241,Ra-222,
Cs-137andCo-60
Soil, sludge,
crushed asphalt
or concrete
Most effective with
optimum pH levels
within a relatively narrow
range
Study demonstrated
removal of 80 to 95%
uranium from pond
water, depending on pH,
reagent, and reagent
dosage
Soil must first be
excavated, therefore
poses a health and safety
risk to workers and the
local community
Soil residuals will
requires further treatment
and/or disposal
The volume of
contaminated soils can be
reduced by >90%
Soil Washing
(Ex-situ process)
Demonstrated for
thorium, uranium,
cesium, radium, and
plutonium
Soil, slurry
Appropriate where
radioactive contaminants
are closely associated
with fine soil particles
(size between 0.25 and 2
mm)
Soil character, moisture
content, particle size
distribution, contaminant
concentrations and
solubilities affect
efficiency/operability of
soil washer
Process may not work for
humus soil
Technology is not yet
fully demonstrated for
radioactive contamination
16
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Exhibit 1-5: Summary of Solid and Liquid Media Technologies (Cont.)
TECHNOLOGY
CONTAMINANT
MEDIUM
CONSIDERATIONS
Flotation
(Ex-situ process)
Demonstrated for
uranium and
plutonium
Soil, sediment
Effectiveness varies with
soil characteristics
Most effective at
separating soil particles
in the size range of 0.1 to
0.01mm
Has not been fully
demonstrated for
radioactive contamination
Testing showed reduced
radium concentrations in
uranium mill tailings
from 290 -300 pCi/g to
50-60 pCi/g
Microfiltration
Demonstrated for
uranium, americium,
and plutonium
Groundwater,
surface water,
slurry,
wastewater
Best suited for separating
very fine particles (0.1 to
0.001 microns) from
liquid media
Removal efficiencies
were greater than 99%
for uranium, plutonium,
americium
Reverse Osmosis
Demonstrated for
uranium
Groundwater,
surface water,
slurry,
wastewater
Affected by the size and
charge of the ion being
treated
Aqueous waste stream
must be treated or
disposed of
Reduced uranium
concentrations in
groundwater by 99%
Carbon Adsorption
Demonstrated for
uranium, Co-60, and
Ru-106
Groundwater,
surface water,
slurry,
wastewater
Presence of iron may
promote fouling of
carbon
Effective in reducing
groundwater uranium
concentrations from 26-
100ug/lto
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Exhibit 1-5: Summary of Solid and Liquid Media Technologies (Cont.)
TECHNOLOGY
CONTAMINANT
MEDIUM
CONSIDERATIONS
Aeration
Demonstrated for
radon
Groundwater,
surface water,
slurry,
wastewater
Primarily used in radon
removal
Radon removal efficiency
ranged from 90% to
99.6% in water
In-Situ
Vitrification
Demonstrated for
most radioactive
waste
Soil, sludge,
sediment, mine
tailings
High moisture/salt
content in soil can
increase electrical
needs/cost
Plan for void
volumes/percentages of
metals, rubble,
combustible organics
Requires off-gas control
systems
Volatile radionuclides
trapped during the
process require further
treatment and/or disposal
Does not affect
radioactivity
Ex-Situ
Vitrification
Demonstrated for
most radioactive
waste including low-
level and transuranic
wastes
Soils, debris,
sediment, buried
waste, metals
Fixed and rotating hearth
applications are available
Requires off-gas control
systems
Volatile radionuclides
trapped during the
process require further
treatment and/or disposal
Has not been fully
demonstrated
Costs are considered high
Does not affect
radioactivity
These considerations are general in nature; please refer to profiles for a complete discussion of each technology
18
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1.5 ORGANIZATION AND USE OF THIS GUIDE
The remainder of this Guide contains the following components:
Section II provides treatment technologies for solid media grouped under five
categories:
Containment - technologies that provide barriers between contaminated
and uncontaminated media to prevent contaminant migration and shield
potential receptors from radiation
Solidification/Stabilization - technologies that add material to the
contaminated waste and soil to produce a leach-resistant media, which
binds the waste
Chemical Separation - technologies that use the contaminants' chemical
properties to separate contaminants from the contaminated media
Physical Separation - technologies that rely on the contaminants' physical
properties to separate contaminants from the contaminated media.
Vitrification - a technology that heats contaminated media sufficiently to
liquefy the media and its contaminants and, upon cooling, traps the
contaminants in a glass matrix.
Exhibit 1-6 highlights the five types of solid media technologies discussed.
19
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Solidification/
Stabilization
Material
Disposal
In Place
Material
Disposal In
Place, On-Site,
Or Off-site
Material
Disposal In
Place, Or
Off-site After
Processing
Waste Material
To Licensed
Facility
Waste Material
To Licensed
Facility
Exhibit 1-6: Solid Media Technology Categories
20
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Section III which describes five treatment technologies for contaminated liquid media,
grouped under chemical and physical separation categories:
Chemical Separation - technologies that use chemical reagents or
exchange mechanisms to bind up or immobilize radionuclides based on
their chemical properties.
Physical Separation - technologies that rely on physical properties such as
size or volatility to separate and immobilize radionuclides.
Following sections II and III are the Appendices, containing a discussion of
radioactivity concepts, glossary of terms, and a bibliography of general references for those
readers who wish to research the technologies further.
Exhibit 1-7 suggests how the profiles in this Guide can be used to identify potential
treatment technologies for their sites.
Exhibit 1-7: Using the Technology Profiles
To locate information in the profiles, take the following steps...
Note which contaminants and media the technology addresses.
Note any distinctive operating or site characteristics that influence the technology's
effectiveness; consider whether these circumstances permit or rule out this technology.
Note special factors to be considered, for example, cost, safety of nearby populations, or
topography, if they significantly influence the choice of appropriate technologies.
Identify all relevant technologies using the first two steps.
Assess how those technologies have performed according to the NCP criteria.
Identify technologies to evaluate further. Consult your Regional Decision Team and
additional resources identified in the Technology Profiles.
You are encouraged to provide feedback for future updates to this guide in the form of
comments, suggestions and new sources of information to the address on page v.
21
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SECTION II
SOLID MEDIA TECHNOLOGY PROFILES
23
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Preceeding Page Blank
CONTAINMENT TECHNOLOGIES
CONTAINMENT TECHNOLOGIES
J
Containment technologies are designed to isolate contaminated materials in order to
prevent exposure to humans and the environment. Often, volume reduction or other treatment
technologies are applied to radioactive waste prior to containment. Regardless of the
technologies applied, however, there is generally a portion of the radioactive material that
requires long-term disposal. Exceptions include radionuclides with relatively short half-lives
(e.g. Cobalt-60), in which case containment for shorter periods of time may be appropriate.
Because most radionuclides require long-term disposal, remedies for radioactively
contaminated sites usually employ containment technologies. Some containment
technologies are designed to prevent horizontal contaminant migration, some to prevent
vertical migration, and others to prevent any form of migration. To achieve the necessary
level of isolation, different containment technologies are often used in conjunction with one
another.
The following containment technologies used to isolate radioactive waste are
discussed in this section: capping (containment in place); land encapsulation (excavation and
disposal, on-site or off-site); cryogenic barriers (containment in place); vertical barriers
(containment in place).
25
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Preceeding Page Blank
CAPPING
2.1 CAPPING
J
2.1.1 Technology Characterization
Description
Capping is a containment technology that forms a barrier between the
contaminated media and the surface, thereby shielding humans and the environment
from radiation effects. Capping radioactive waste involves covering the contaminated
media with a cap sufficiently thick and impermeable to minimize the migration of
waste to the surface and to control windblown contamination. A cap must also restrict
surface water infiltration into the contaminated subsurface to reduce the potential for
contaminants to leach from the site. Capping does not prevent horizontal migration of
contaminants due to groundwater flow, however, it can be used in conjunction with
vertical walls to produce an essentially complete structure surrounding the waste
mass.7 A cap can be placed over a large, discrete contaminated area or it can be a
continuous cover over several smaller contaminated areas close together. A cap must
extend a few feet beyond the perimeter of the contaminated area to prevent lateral
infiltration of rain.
Caps can be made of a variety of materials, each of which provides a different
degree of protection. Capping materials include synthetic membrane liners such as
geomembranes (e.g. high density polyethylene, HDPE), asphalt, cement, and natural
low-permeability soils such as clay. A cap is usually a combination of materials
layered one on top of the other. A typical cap for containing radioactive media might
consist of several feet of compacted filler, a geomembrane, a layer of compacted clay,
another geomembrane, and several feet of top soil (see Exhibit 2-1). A layer of ground
cover vegetation may be applied to the surface of the cap to reduce soil erosion and
limit the potential for precipitation to permeate the cap.
Caps for radium-contaminated sites must be designed to confine gaseous radon
until it has essentially decayed. If synthetic membrane liners are not used, the depth of
cover required is about 150 cm for radon-222 and 5 cm for radon-220. In addition,
approximately 60 cm of soil cover is required for gamma radiation shielding.8 Long-
U.S. Environmental Protection Agency, Office of Research and Developmenifechnological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
slbid.
27
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CAPPING
term durability of the cap materials should be considered in order to effectively isolate
the radioactive waste. For example, HDPE is susceptible to degradation from sunlight
as well as chemical and biological degradation. However, these degradation
mechanisms are generally eliminated by burial of the membrane in cover systems that
are three meters in depth, thus increasing the longevity of the geomembrane.9
Capping is a well-known technology that is relatively easy to implement.10
Site-specific conditions such as climate need to be considered in determining an
appropriate cap design. Many alternatives are possible, depending on the need for
water control at the site. Software programs are currently being developed for
commercial use to ensure that site managers use the best scientific information on
barrier design and performance to select the best remediation practice within the
constraints of technical performance, regulatory requirements, and cost.11
Soil Contaminated with
Radioactive Waste
Frobel, R. "Geomembranes in Surface Barriers'' Environmental Restoration Conference, 1995.
Oak Ridge National Laboratory,Oa£ Ridge National Laboratory Technology Logic Diagrams, Volume 2, Part B, Remedial
Action, ORNL/M-2751/V2/PI.B, September 1993.
U.S. Department of Energy,Decision Support System, Technology Catalog. 1994.
28
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CAPPING
Exhibit 2-1: Capping
Target Contaminant Groups
Capping can be used to contain all types of waste, including radioactive
waste materials found in the soil matrix, debris, and radioactively contaminated
landfills.
Technology Operating Characteristics
Exhibit 2-2 summarizes the operating characteristics of capping.
Exhibit 2-2: Technical Characteristics of Capping
Characteristic
Description
Destruction and
Removal
Efficiencies
(DREs)
Emissions:
Gaseous and
Particulate
Costs: Capital and
O&M
Reliability
Process Time
Applicable Media
Pretreatment/Site
Requirements
Type and Quantity
of Residuals
Disposal Needs
and Options
Post-treatment
Conditions
Ability to Monitor
Effectiveness
Not Applicable
Potential for fugitive dust and gas emissions during cap
construction. Radon gas collection and treatment systems may
be required if buildup occurs once the cap is installed.
Most costs are capital; O&M costs include monitoring and
maintenance costs. Cost depends on the type of cap required;
typical clay caps are $10 to $15 per square yard, where RCRA
caps with multiple layers are $25 to $30 per square yard.
Reliable when properly maintained and not impacted by
development or other disruptive activities at the site.
Objectives are met as soon as cap is in place.
Soil, mill tailings, sediment, drummed waste, boxed waste and
bulk waste
Waste may need to be consolidated before cap construction.
Contaminated media is not processed or removed.
Not Applicable
Institutional controls, such as deed, site access, and land use
restrictions, are usually required.
Radon gas emissions from the subsurface, cap integrity, and
the effects of contamination on groundwater can be monitored.
29
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CAPPING
Site Considerations
Site conditions such as fluctuations in air temperature, precipitation, or
subsidence may affect the cap's integrity by causing cracking, settling, or erosion.
Biological processes such as intrusion of plant roots and burrowing animals can
also affect the cap's integrity. These considerations are particularly important for
containing radioactive waste because of the long-term isolation required. In order
to promote the cap's longevity, infiltration barriers should be covered by a soil
layer sufficiently thick to extend below the frost line to accommodate rooting
depths of native plants and to extend below the probable depth of animal
burrows.12
Characterization of soils is not as critical for capping as it is for more
complex remedial approaches that depend on soil conditions (e.g. stabilization). In
dry and porous soils with high radium concentrations, venting may be required to
control radon gas migration and buildup below the ground surface. Such venting
may violate applicable emission standards unless the radon is collected and
treated.13 The impact that groundwater flow could have on contaminant migration
at the site should be considered. Capping may not be a feasible alternative at sites
with low topography, flooding, or a shallow groundwater table; these conditions
encourage horizontal migration and decrease the cap's effectiveness.
2.1.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
Capping protects human health by putting a barrier between the radioactive
waste and the surface environment, thus preventing human contact with the
contaminated media. Depending on the environmental receptors at the site,
however, capping may not adequately protect the environment. During cap
installation nearby populations and site workers are at risk of exposure to
contaminants from fugitive dust and gas emissions. To mitigate these risks,
controlling fugitive dust and operating under favorable meteorological conditions
should be practiced. Over the long term, contaminants may migrate via contact
with groundwater, defeating containment objectives.
12
Oak Ridge National Laboratory,Natural, Physical, and Biological Processes Compromise the Long Term Performance of
Compacted Soil Caps. Environmental Restoration Conference, 1995.
U.S. Environmental Protection Agency Background Information Document for Radiation Site Cleanup Proposed Rule, Revised
Draft, August 1995.
30
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CAPPING
Compliance with ARARs
At sites with mixed waste, the cap must comply with Resource
Conservation and Recovery Act (RCRA) cap construction guidelines. At DOE
facilities with low-level waste, the cap must comply with the performance criteria
outlined in DOE Order 5820.2A. Compliance with other ARARs must be
determined on a site-specific basis.
Long-Term Effectiveness
Capping does not remove the source of radioactivity from the area of
concern. It simply impedes direct exposure to contaminants in soil and the release
of contamination by isolating the contaminated media. Capping may be
inadequate as a long-term solution due to the potential for weathering, cracking,
subsidence or other deterioration. Monitoring radon gas emissions from the
subsurface, cap integrity, and groundwater is required to ensure the long-term
effectiveness of this technology. Over the long term, horizontal migration of
contaminants may occur via contact with groundwater, even if the cap remains
intact.
Reduction of Radiotoxicity. Mobility, or Volume
Capping does not reduce the radiotoxicity or volume of the contaminated
media. While capping significantly reduces vertical mobility due to surface water
leaching, it does not restrict horizontal mobility via contact with groundwater.
Short-Term Effectiveness
During cap construction, capping may pose risks to surrounding
communities and site workers by exposing them to the contaminated media and
fugitive dust and gas emissions. If excavation and waste consolidation from other
parts of the site are required, waste transport can increase exposure risk. The cap's
effectiveness in significantly reducing exposure risks occurs as soon as the cap is
in place.
Implementability
Capping is a mature, well-known technology that is relatively easy to
implement. Materials and equipment are usually readily available. Since the
treatment is entirely in-situ, no offsite activity is necessary to manage, treat, or
store the contaminated waste. Air temperature, precipitation, topography, other
site-specific conditions, and subsurface conditions may affect implementation. If
31
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CAPPING
fugitive dust emissions are a problem during implementation, dust suppression
measures are readily available. Installation of a gas collection and treatment
system may be necessary due to radon and/or methane gas emissions.
Cost
Most costs are capital. O&M costs generally include monitoring and
possible cap repairs. The cost of capping depends on the size and type of the cap
required. A typical clay cap costs approximately $10 to $15 per square yard, while
a typical RCRA cap (more likely to be used for radioactive waste) costs between
$25 to $30 per square yard.14 The increased cost of the RCRA cap reflects the use
of multiple layers, including geomembranes. Other major cost drivers for this
technology include gas collection and treatment, if necessary, and long-term
monitoring and maintenance.15
2.1.3 Summary
Capping involves covering radioactive waste to reduce or eliminate
exposure pathways. Because contaminated media are not removed or treated, there
is a residual risk of exposure over the long-term due to cap disturbance and
possible horizontal migration in groundwater. If the cap remains undisturbed and
horizontal migration is minimal, capping protects human health by putting a barrier
between the radioactively contaminated waste and the surface. During cap
construction, surrounding communities and site workers may be exposed to
fugitive dust and gas emissions.
The most significant advantages of capping are the ease of application, the
fact that it is a well-known technology, and that it is reliable when properly
maintained. The most significant disadvantages of capping are that the
contaminated media is not treated or removed and that it does not limit horizontal
migration of the contaminants via groundwater.
Exhibit 2-3 summarizes the data and analyses in this profile and can be
used for technology comparison.
TJ.S. Department of Defense, Environmental Technology Transfer Committeeftetnediation Technologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
32
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CAPPING
Exhibit 2-3: NCP Criteria for Capping
NCP Criterion
Evaluation
Performance Data
Overall
Effectiveness
Highly effective and
reliable when
maintained properly.16
Depends on cap type and
degree to which it remains
intact over time.
Can control direct contact
with contaminated media
and decay gases and prevent
vertical migration of
contamination to the surface.
Compliance with
ARARs
Sites with mixed waste
must comply with
RCRA capping
requirements.
DOE sites with low-
level waste must
comply with DOE
Order 5820.2A.
Compliance with soil and
groundwater ARARs must
be determined on a site-
specific basis.
Reduction of
Radiotoxicity,
Mobility or
Volume
Does not decrease
radiotoxicity or volume
of the contaminated
media.
Reduces vertical but
not horizontal mobility.
Does not remove or
remediate contaminated
media.
Has been shown to reduce
vertical contaminant
migration.
Long-Term
Effectiveness and
Permanence
Effective over long-
term, as long as cap
remains intact.
Horizontal migration of
contaminants is
possible over long-
term.
Dependent on proper cap
maintenance and lack of
disturbance.
Difficult to monitor or
evaluate cap performance
once installed.
U.S. Environmental Protection Agency, Office of Research and Developmentfechnological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
33
-------
CAPPING
Exhibit 2-3: NCP Criteria for Capping (Cont.)
NCP Criterion
Evaluation
Performance Data
Short-Term
Effectiveness
Effective means of
containing
contamination in short-
term.
Requires control of
potential worker and
community exposure to
contamination during
implementation.
Prevents contaminant
exposure as soon as cap is in
place.
May expose community or
workers to contamination
during construction.
Implementability
Easy to implement.
Relevant site-specific
factors must be
considered prior to
implementation.
No offsite activity is
necessary to manage, treat,
or store the waste.
Site-specific conditions such
as climate and topography
may impact cap integrity.
Cost
Relatively low capital
cost.17
Maintenance over very
long-term will affect
overall cost.
Costs between $10 and $30
per square yard are
associated with this
technology.18
O&M costs include
monitoring and cap
maintenance.
Ibid.
U.S. Department of Defense, Environmental Technology Transfer Committeeftemediation Technologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
34
-------
LAND ENCAPSULATION
2.2 LAND ENCAPSULATION
J
2.2.1 Technology Characterization
Description
Land encapsulation is a proven, well-demonstrated containment
technology19 that is generally used at the disposal stage of radioactive waste
management. Other technologies are often used to reduce the volume of the
radioactive waste, after which land encapsulation is used to effectively dispose of
the treated waste. Land encapsulation involves excavating the disposal area and
installing a liner or other impermeable material in the excavated area. Radioactive
waste and/or residuals requiring disposal are then transported and backfilled into
the lined, excavated area and an appropriate cap is applied (see Exhibit 2-4)
(detailed description of capping technology is provided in Section 2.1).
Facility design guidelines developed by the Nuclear Regulatory
Commission (NRC) and EPA for commercial, mixed low-level waste (LLW)
disposal facilities include two or more composite liners (e.g., upper geomembrane
and compacted soil layer) and a leachate collection system located above and
between the liners. The facility design minimizes water contact with the
encapsulated waste as required by the NRC.20
While land encapsulation can occur on site, because obtaining necessary
approvals to dispose of radioactive waste is difficult, most waste is transported to
off site land encapsulation facilities. The Low-Level Radioactive Waste Policy
Amendments Act of 1985 (LLRWPAA) requires states and compacts to develop
siting plans for LLW disposal facilities.21 A remote area dedicated by a state or
other government entity to radioactive waste containment could receive waste from
other sources within and outside that jurisdiction, given the appropriate approvals.
There are currently three licensed LLW disposal facilities; additional LLW
facilities are expected to become operational in the near future.
\J.S. Environmental Protection Agency, Office of Research and DevelopmentJ'echnological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
21
Ibid.
35
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LAND ENCAPSULATION
Given the long period of time that radioactive waste will be a hazard, the
encapsulation facility must heed the degradational characteristics of construction
materials more than usual for hazardous waste disposal sites.22 Current research
has focused on developing new types of materials to improve liner integrity and to
reduce possible radionuclide migration. One approach involves using smectite
clays, which can both bind hazardous cations and resist water. Such clays could
increase resistance to leaching of the radionuclides by water.23 Another developing
technology is in-situ encapsulation of contaminant waste, in which the natural
processes that convert unconsolidated soil, sand, and gravel sedimentary rock are
simulated. Unlike traditional liners of silty-clay soils, this technology eliminates
the potential for waste migration into groundwater.24
Exhibit 2-4: Land Encapsulation
Ibid.
Argonne National Laboratory. "Encapsulation of Hazardous Ions in Smectite Clays" Project Description, 1994.
:4
Terran Environmental Inc. "In-situ Encapsulation of Buried Waste" Project Description , 1994.
36
-------
LAND ENCAPSULATION
Target Contaminant Groups
Land encapsulation is generally used as a final disposal method. Thus it can be
applied to a wide variety of contaminants, including LLW, and mixed and commercial
wastes (definitions of LLW, mixed waste and high-level waste are provided in
Appendix-A). Land encapsulation may be appropriate for radionuclides, whether or
not they have been extracted from a contaminated medium. Currently, no operating
land encapsulation facilities accept high-level waste.
Technology Operating Characteristics
Exhibit 2-5 summarizes the operating characteristics of land encapsulation.
Exhibit 2-5: Technical Characteristics of Land Encapsulation
Characteristic
Description
Destruction and
Removal Efficiencies
(DREs)
Emissions: Gaseous
and Particulate
Costs: Capital and
O&M
Reliability
Process Time
Applicable Media
Pretreatment/Site
Requirements
Not applicable
Gas and dust emissions from construction of the land encapsulation
facility, excavation of the waste, and transportation of material are
potential risks to workers, the community, and the environment.
Materials and installation costs range from $276 to 895 per cubic
meter. First-year O&M costs are $0.045 per cubic meter. 25
These costs include the cost of excavation and transportation, but not
acquisition of a disposal site.
Highly certain for 100-1000 years.26 Design and mitigation procedures
can improve reliability.
Not applicable. "Process time" may include the time devoted to either
transportation of the material or construction time for a new land
encapsulation facility. Once material reaches the facility, the process
is complete.
Soil, landfill leachates, sediments, bulk waste
The waste must first be excavated before being transported to the
encapsulation facility. Other technologies may be applied to the waste
prior to land encapsulation. In addition to licensing and/or regulatory
approvals, excavation is necessary to construct a new land
encapsulation facility.
U.S. Environmental Protection Agency, Office of Research and DevelopmeniTechnological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
26U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Respons&issessment of Technologies for the
Remediation ofRadioactively Contaminated Superfund Sites, EPA/540/2-90/001, January 1990.
37
-------
LAND ENCAPSULATION
Exhibit 2-5: Technical Characteristics of Land Encapsulation (Cont.)
Characteristic
Description
Type and Quantity of
Residuals
Disposal Needs and
Options
Post-treatment
Conditions
Ability to Monitor
Effectiveness
Not applicable
Generally, dependent on current licensed operating disposal facilities.
Siting of a new disposal facility must comply with applicable
regulations.
Regulatory compliance procedures apply (i.e., monitoring and
mitigation).
Effectiveness of the encapsulation facility can be monitored by
leachate collection systems and groundwater monitoring wells.
Site Considerations
Since there may be considerable public antipathy to this technology, the
primary site consideration is location (e.g., proximity to residential areas).
Transportation of large volumes of radioactive materials entails certain risks. Safety
and licensing and/or regulatory approval considerations are more cumbersome if
radionuclides have been concentrated by extraction and separation processes.
Currently, there are three NRC-licensed commercial LLW disposal facilities: Hanford,
Washington; Barnwell, South Carolina; and Clive, Utah. The only commercial
disposal facility licensed for mixed waste is in Clive, Utah.
Site characteristics such as topography, seasonal variations in temperature and
precipitation and seismic activity may impact the land encapsulation facility's integrity
and must be considered. Relative to other technologies, minimal information about site
soil characteristics is required prior to land encapsulation.
2.2.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
Environmental and human health risks are most prevalent when radioactive
materials are being excavated and transported to an offsite land encapsulation facility.
Transportation of large volumes of radioactive materials involves high costs and risks.
Additional risks include excavation of radioactive material (if applicable) and handling
these materials in preparation for transport to an encapsulation facility. Risks to site
38
-------
LAND ENCAPSULATION
workers from radioactive material excavation can be reduced by using a remote
excavation system for buried waste retrieval.27
The possibility that radioactive material in the land encapsulation facility could
leach into the environment is also a risk, especially if it leaches into groundwater.
Potential health impacts to site workers and residents also include exposure to fugitive
dust emissions and fugitive gases, such as radon.
Compliance with ARARs
The NRC and EPA have jointly developed guidance on land encapsulation
siting and designing commercial, mixed, low-level radioactive and hazardous waste
land encapsulation disposal facilities.28 The siting, construction, and operation of a
land encapsulation facility at a DOE site must comply with DOE Order 5820.2A.
Long-Term Effectiveness
As a disposal facility, land encapsulation is designed to be a long-term solution
to waste disposal. However, since land encapsulation does not reduce the volume or
radioactivity of the contaminants, design features such as liner integrity, monitoring,
and mitigation procedures are necessary to ensure effectiveness. Proximity to
residential areas, site characteristics, and land management plans all play a critical role
in the continued effectiveness of a land encapsulation facility.
Additionally, an appropriate site may need to be located for disposing of
radionuclides that have been extracted and separated, if a land encapsulation site does
not accept such materials.
Reduction of Radiotoxicity. Mobility, or Volume
Land encapsulation will not reduce the radiotoxicity or volume of the
contaminated material. A sufficiently encapsulated facility will significantly reduce
vertical and horizontal mobility.
Oak Ridge National Laboratory and Idaho National Engineering Laboratory technology Catalog Site Remediation Profiles:
Remote Excavation System - 1993.
28
U.S. Environmental Protection Agency, Office of Research and DevelopmentJ'echnological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
39
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LAND ENCAPSULATION
Short-Term Effectiveness
If a land encapsulation facility provides sufficient capacity, a completely
impermeable liner and cover can prevent risks to human health and the environment.
During development of the land encapsulation facility, and excavation and
transportation of waste to the facility, however, local residents and site workers may be
exposed to dust and gas emissions.
Implementability
For on site encapsulation, safety and siting approval considerations may impact
implementation because they can be very difficult to obtain. Generally, implementing
a new land encapsulation facility is a lengthy process due to public concerns. Finding
an existing, secure site outside the containment property that will accept radioactive
waste may also be difficult. Safety and permitting issues also apply to transporting
and handling the waste outside the boundaries of the contaminated property.
The materials and equipment necessary to construct land encapsulation
facilities are generally readily available. Of the three existing NRC-licensed sites,
however, restrictions apply as to the types of waste accepted (such as radium waste at
Barnwell, SC)29. Also, the Utah facility is restricted to 1 l(e)(2) byproduct material,
Class A low-level waste and mixed low-level waste. The Hanford facility currently
accepts only waste from the Northwest and Rocky Mountain compacts.
Cost
The quantity of material for disposal most influences the cost. For large
volumes of material it may be desirable to reduce the volume through other treatments
prior to disposal. Costs also depend on the distance the waste must be transported to a
land encapsulation site; on site land encapsulation is less expensive than off site
encapsulation. The materials and installation costs range from $276 to 895 per cubic
meter of soil, while first-year O&M costs are $0.045 per cubic meter.30 Remote
40
-------
LAND ENCAPSULATION
excavation of a contaminated site costs from $203 to 244 per cubic foot, not including
transportation or disposal costs.31
2.2.3 Summary
Land encapsulation is a containment technology generally used at the disposal
stage of radioactive waste management. Land encapsulation facilities are designed to
be long-term solutions to waste disposal, although they do not reduce the radiotoxicity
or volume of waste.
The following factors may limit the applicability and effectiveness of this
process:
difficulty in obtaining permits for siting and constructing a land
encapsulation facility for radioactive waste;
likelihood of liner deterioration, liner penetration, and leaching over the
long-term;
limited number of permitted facilities accepting radioactive waste;
risks associated with the possible excavation, handling, and
transportation of radioactive waste.
Exhibit 2-6 summarizes the data and analyses presented in this profile and can
be used for technology comparison.
Exhibit 2-6: NCP Criteria for Land Encapsulation
NCP Criterion
Evaluation
Performance Data
Overall Protectiveness
Covers and liners are
designed to encapsulate
waste.
Eliminates radiation
effects. Site
characteristics and
monitoring are crucial.
Compliance with
ARARs
Required in permit process.
Joint NRC-EPA siting and
facility design guidance or
DOE Order 5820.2A
applies.
For off-site, transport
regulations apply.
Oak Ridge National Laboratory and Idaho National Engineering Laboratory Technology Catalog Site Remediation Profiles:
Remote Excavation System - 1993.
41
-------
LAND ENCAPSULATION
Exhibit 2-6: NCP Criteria for Land Encapsulation (Cont.)
NCP Criterion
Evaluation
Performance Data
Reduction of
Radiotoxicity,
Mobility, or Volume
Does not reduce
radiotoxicity or volume;
reduces vertical and
horizontal mobility.
Involves immobilization
but not removal or
destruction.
Long-Term
Effectiveness and
Permanence
Designed to be a long-term
solution for disposal.
A proven, well-
demonstrated technology.
Reliable for 100-1000
years.
Site characteristics, liner
integrity, and management
determine effectiveness.
Short-Term
Effectiveness
No reduction of
radiotoxicity or volume.
Effectively contains waste
in the short-term.
Potential to expose local
residents and site workers
to fugitive dust and gas
emissions.
Implementability
Difficult to gain approval
for building a facility.
Substantial permit
requirements.
Construction processes are
not difficult or time-
consuming.
Significant public
antipathy.
Easy to construct under
appropriate site conditions.
Cost
Development of a new
facility is expensive. Costs
are reduced if facility is in
place.
Capital costs range from
$276 to $895 per cubic
meter of contaminated
soil. First-year O&M
costs are $.045 per cubic
meter.
42
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CRYOGENIC BARRIERS
2.3 CRYOGENIC BARRIERS
J
2.3.1 Technology Characterization
Description
A cryogenic barrier is a containment technology that freezes soil to create an
ice barrier around a contaminated zone. This barrier reduces the mobility of
radionuclide contaminants by confining the materials and any contaminated
groundwater that might otherwise flow through the site. To create the barrier, two
rows of freeze pipes are inserted in an array outside and beneath the contaminated
zone, using standard well drilling techniques. The first row of freeze pipes is installed
around the circumference of the site at angles below the contaminated zone; the
second set of freeze pipes is installed a set distance away from the first row. Careful
installation of the piping is necessary to ensure complete barrier formation. Once
installed, the array of pipes is connected via a manifold to a refrigeration plant. In a
completely closed system, the pipes carry a coolant that freezes the inner volume
between the two rows of freeze pipes to create the ice barrier. Coolants consist of
environmentally benign brines such as salt water, propylene glycol, or calcium
chloride. Soil moisture content of 14 percent to ISpercent is considered optimal for
implementing the cryogenic barrier. 32 Injection pipes can be placed within the barrier
to optimize soil moisture and to insert monitoring devices (see Exhibit 2-7).
Laboratory tests with Cesium-137 showed no detectable diffusion through the
cryogenic barrier, although sorption on soil grains may have been responsible for the
immobility.33
Cryogenic barriers are often used when the waste mass is too large for practical
treatment and where soluble and mobile constituents pose an imminent threat to a
drinking water source. Cryogenic barriers can be positioned to maximum depths of
1,000 feet and do not require excavation for installation.34 Barrier thickness, ranging
from 15 to 50 feet, and temperature may vary to suit site conditions. Ongoing
refrigeration is required to maintain cryogenic barriers; heat generated from high-level
Cryocell, Responses to Commonly Asked Questions About Frozen Soil Barriers Containing Hazardous Waste.
U.S. Department of Energy, Frozen Soil Barrier Technology, Innovative Technology Summary Report, DOE/EM-0273, April
1995.
Oak Ridge National Laboratory, Oak Ridge National Laboratory Technology Logic Diagrams, Volume technology Evaluation
Data Sheets, Part B, Dismantlement - Remedial Action ORNL/M-2751/V3/PI.B, September 1993.
43
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CRYOGENIC BARRIERS
radioactive waste can increase the electrical power needs.35 With adequate
refrigeration, the ice does not degrade or weaken over time and is repairable in situ. If
ground movement fractures the barrier, the fissures can be repaired by injecting water
into the leakage area.36
Refrigeration
Source
Freeze Pipes Injection Pipes
Soil Containing
Radioactive Wai
Clean Soil
Barrier
Exhibit 2-7: Cryogenic Barrier
Fremond, M.,Ground Freezing 94, from the Proceedings of the Seventh International Symposium on Ground Freezing, Nancy,
France, October 24-28, 1994.
36
U.S. Environmental Protection Agency, Office of Research and Development£wper/w«rf Innovative Technology Evaluation
Program: Technology Profiles, Seventh Edition, EPA/540/R-94/526, November 1994.
44
-------
CRYOGENIC BARRIERS
Using refrigeration to freeze soils has been employed in large-scale engineering
projects for a number of years. While cryogenic barriers have been field tested, they
have not yet been demonstrated at an actual radionuclide-contaminated site.
Target Contaminant Groups
Cryogenic barriers provide subsurface containment for a wide variety of waste
in soil and groundwater, including radionuclides, metals, and organics. While
cryogenic barriers are used for radionuclides in soluble form, the solubility of the
radionuclides depends on site-specific conditions such as pH and other chemicals
present.
Technology Operating Characteristics
Exhibit 2-8 summarizes the operating characteristics of cryogenic barriers.
Exhibit 2-8: Technical Characteristics of Cryogenic Barriers
Characteristic
Description
Destruction and
Removal Efficiencies
(DREs)
Emissions: Gaseous
and Particulate
Costs: Capital and
O&M
Reliability
Process Time
Not applicable
Not applicable
Costs are based on the volume of frozen soil required to contain the
waste. Capital costs range from $10 to $14 per cubic foot;
operation and maintenance costs are approximately $1 per cubic
foot per year.37
Fully demonstrated for geotechnical applications to construction
sites.38 Field demonstrated at clean sites.39
A cryogenic barrier can be established within a few months.
Containment of the radioactive waste occurs as soon as the barrier
is in place.40
U.S. Department of Energy, Frozen Soil Barrier Technology, Innovative Technology Summary Report DOE/EM-0273, April
1995.
Oak Ridge National Laboratory, Oak Ridge National Laboratory Technology Logic Diagrams, Volume technology Evaluation
Data Sheets, PartB, Dismantlement - Remedial Action ORNL/M-2751/V3/PI.B, September 1993.
RKK, Ltd. Vendor Information.
Fremond, M., Ground Freezing 94, from the Proceedings of the Seventh International Symposium on Ground Freezing, Nancy,
France, October 24-28, 1994.
45
-------
CRYOGENIC BARRIERS
Exhibit 2-8: Technical Characteristics of Cryogenic Barriers (Cont.)
Characteristic Description
Applicable Media
Pretreatment/Site
Requirements
Type and Quantity of
Residuals
Disposal Needs and
Options
Post-treatment
Conditions
Ability to Monitor
Effectiveness
Soil, sediment, leachates, bulk waste, and groundwater
Power for the refrigeration plant to freeze the soil is required. 41
Soil moisture content of 14% to 18% is considered optimal.
Generates no waste stream or residues.42
Not applicable. The contaminated media remain on-site.
All waste remains on site. Refrigeration plant remains on-site to
maintain frozen barrier.
Target contaminants can be monitored using monitoring wells
positioned internally and externally to the barrier. A fiber optics
temperature sensor system can monitor barrier temperature. 43
Potential radioactive emissions from the contaminated area can be
monitored.
Site Considerations
Design criteria for cryogenic barriers is site-specific and depends on waste
type, topography, soil condition, thermal conductivity, and groundwater movement.
Cryogenic barriers are adaptable to any geometry, however drilling technologies may
present a constraint. Power for the refrigeration plant to freeze the soil is required;
remote sites may require electrical power and utility installation.44 Heat from high-
level radioactive waste can increase electrical power needs for maintaining frozen
barriers. In extremely dry soils, moisture must be supplemented with injection pipes
placed within the barrier. For applications in humid and high ambient temperature
Oak Ridge National Laboratory,Oak Ridge National Laboratory Technology Logic Diagrams, Volume 2, Part B, Remedial
Action, ORNL/M-2751/V2/PI.B, September 1993.
U.S. Environmental Protection Agency, Office of Research and Development£«per/w«rf Innovative Technology Evaluation
Program: Technology Profiles, Seventh Edition, EPA/540/R-94/526, November 1994.
Cryocell, Responses to Commonly Asked Questions About Frozen Soil Barriers Containing Hazardous Waste
Oak Ridge National Laboratory,Oak Ridge National Laboratory Technology Logic Diagrams, Volume 2, Part B, Remedial
Action, ORNL/M-2751/V2/PI.B, September 1993.
46
-------
CRYOGENIC BARRIERS
regions, proper ground insulation and near surface refrigerant piping may be required
to ensure that surface to 2-foot depths are adequately frozen.45
2.3.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
Cryogenic barriers protect human health and the environment by reducing
vertical and lateral migration of radioactive contaminants. This technology reduces
risk exposure pathways as long as the pipes and refrigeration system remain intact.
Because the radioactive waste remains in place, there is a potential risk to human
health and the environment from radioactive emissions, particularly for waste located
near the ground surface. These potential emissions should be carefully monitored.
Compliance with ARARs
At DOE sites with low-level waste, cryogenic barriers must meet the
performance criteria outlined in DOE Order 5820.2A. Compliance with other ARARs
must be determined on a site-specific basis.
Long-Term Effectiveness
Cryogenic barriers do not eliminate the radiotoxicity of the contaminants, they
simply limit their vertical and lateral migration. Demonstration results indicate a non-
detectable contaminant diffusion rate through a 15-m cryogenic barrier in thousands of
years.46 However, the frozen barrier must be maintained without any penetrations in
order to be effective in the long-term. Monitoring the performance of cryogenic
barriers with monitoring wells and fiber optics temperature sensory systems is
necessary to ensure the long-term effectiveness of this technology. Also, because the
radioactive waste remains on site, continual monitoring around the contaminated area
is required to detect potential radioactive emissions.
Reduction of Radiotoxicity. Mobility, or Volume
Although cryogenic barriers do not reduce the radiotoxicity or volume of the
contaminated material, they do reduce the horizontal and vertical mobility of
contaminants in soil and groundwater.
45
U.S. Department of Energy, Frozen Soil Barrier Technology, Innovative Technology Summary Report DOE/EM-0273, April
1995.
Cryocell, Responses to Commonly Asked Questions About Frozen Soil Barriers Containing Hazardous Waste
47
-------
CRYOGENIC BARRIERS
Short-Term Effectiveness
Health and safety issues are associated with drilling, prior to installation of the
refrigerant piping. If drilling occurs in contaminated areas, site workers can be
exposed to radiation from the drilling equipment. The cryogenic barrier effectively
contains radioactive waste upon implementation and activation. However, because the
waste remains on-site, radioactive emissions may be produced from the contaminated
area.
Implementability
Site conditions must be evaluated before implementing cryogenic barriers.
Standard well drilling techniques are used to drill or drive the freeze pipes into place.
This technology requires a power source, since a refrigeration plant is needed to
maintain the refrigerant. Necessary equipment, such as mobile refrigeration units,
freeze fittings, insulated piping systems, and drilling equipment, is readily available.
The establishment of a complete cryogenic barrier system can be implemented, using
large-scale temporary refrigeration equipment, in just a few months.
Cost
Costs are based on the volume of frozen soil required to effectively contain the
radioactive waste. Total capital cost for the cryogenic barrier is estimated to range
between $10 to $14 per cubic foot. Using more expensive cryogenics (e.g., liquid
nitrogen) in areas with low freezing points could increase capital costs.47 Average
operation and maintenance costs are approximately $1 per cubic foot per year. Heat
from high-level radioactive waste may increase electrical power needs and
maintenance costs.
2.3.3 Summary
A cryogenic barrier is a containment technology that prevents vertical and
horizontal migration of contaminants, including radionuclides. The technology
involves installing freeze pipes outside and beneath the contaminated zone to form an
ice barrier. Cryogenic barriers are effective upon implementation and provide long-
term reduction in risk exposure pathways, as long as the pipes and refrigeration system
U.S. Department of Energy, Frozen Soil Barrier Technology, Innovative Technology Summary Report DOE/EM-0273, April
1995.
48
-------
CRYOGENIC BARRIERS
remain intact. A monitoring system can be incorporated within and around the
cryogenic barriers to ensure effectiveness.
Cryogenic barriers have been fully demonstrated for geotechnical applications
to construction sites, and have been field demonstrated at clean sites. The waste type,
topography, soil condition, thermal conductivity, and groundwater movement of a
specific site must be assessed prior to implementation. In order for cryogenic barriers
to be effective, soil moisture must be adequate and a suitable power source must be
available at the site. The technology's advantages include in-situ application, which
reduces the potential exposure to radionuclides, and relatively easy barrier
maintenance. Disadvantages of cryogenic barriers include the potential for radioactive
emissions from the contaminated area and the need for ongoing refrigeration to
maintain the barrier.
Exhibit 2-9 summarizes the data and analyses presented in this profile and can
be used for technology comparison.
Exhibit 2-9: NCP Criteria for Cryogenic Barriers
NCP Criterion
Evaluation
Performance Data
Overall Protectiveness
Eliminates risks of
migration by containing of
waste.
Potential radioactive
emissions from the
contaminated area,
particularly if waste is
located near the ground
surface.
Useful for reducing migration of
contaminants.
Compliance with
ARARs
Compliance with soil and
groundwater ARARs must
be determined on a site-
specific basis.
DOE sites with low-level waste
must comply with DOE Order
5820.2A.
Reduction of
Radiotoxicity,
Mobility, or Volume
Reduces mobility, but not
radiotoxicity or volume, of
contaminated media.
Process does not remove or
reduce contaminants.
Reduces vertical and lateral
migration of contaminants.
49
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CRYOGENIC BARRIERS
Exhibit 2-9: NCP Criteria for Cryogenic Barriers (Cont.)
NCP Criterion
Long-Term
Effectiveness and
Permanence
Evaluation
Leaves untreated
contaminated media in
place.
Potential radioactive
emissions from the
contaminated area.
Long-term barrier
effectiveness depends on
proper maintenance.
Performance Data
Demonstration results show a
nondetectable contaminant
diffusion rate through a 15-m
cryogenic barrier in thousands of
years.
A monitoring system should be
incorporated to evaluate the
barrier's effectiveness and to
detect radioactive emissions.
Short-Term
Effectiveness
Effective in reducing
contaminant migration
once the barrier is in place.
Barriers can be fully
implemented within 3
months.
Potential risk of exposure
to site workers if drilling
occurs in contaminated
areas.
Requires large-scale temporary
refrigeration equipment for
response in the short-term.
Implementability
Equipment and power is
needed to freeze the soil.
Site-specific
characterization is needed.
No offsite activity is necessary
to treat or store the waste.
Depends on waste type,
topography, soil condition,
thermal conductivity, and
groundwater movement.
Cost
Costs are mainly
associated with electrical
power needs and are
dependent on the size of
the contaminated area and
the heat produced by the
contained waste.
Capital costs are reported to
range from $ 10 to $ 14 per cubic
foot. O&M costs are
approximately $1 per cubic foot
per year.
Heat from high-level radioactive
waste can increase O&M costs.
50
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VERTICAL BARRIERS
2.4 VERTICAL BARRIERS
J
2.4.1 Technology Characterization
Description
A vertical barrier is a containment technology that is installed around a
contaminated zone to help confine radioactive waste and any contaminated
groundwater that might otherwise flow from the site. Vertical barriers also divert
uncontaminated groundwater flow away from a site. Vertical barriers must reach
down to an impermeable natural horizontal barrier, such as a clay zone, in order to
effectively impede groundwater flow. This technology is often used when the waste
mass is too large to practically treat and where soluble and mobile constituents pose an
imminent threat to a drinking water source. Vertical barriers are frequently used in
conjunction with a surface cap to produce an essentially complete containment
structure.48 Two types of vertical barriers used to contain radioactive waste are slurry
walls and grout curtains.
Slurry walls are subsurface barriers that consist of a vertically excavated trench
filled with a slurry. The slurry both hydraulically shores the trench to prevent the
collapse of the side walls during excavation and produces a barrier to groundwater
flow (see Exhibit 2-10). The slurry is generally a mix of bentonite and water or
cement, bentonite, and water.49 When a strong vertical barrier is required, diaphragm
walls are constructed with pre-cast or cast-in-place concrete panels. Composite slurry
walls, consisting of an impervious artificial barrier in a wall excavated with self-
hardening slurry, are more resistant to chemical attacks and also reduce the barrier's
hydraulic conductivity.50 Slurry walls are generally 0.6 to 1.2 meters (2 to 4 feet) thick
TJ.S. Environmental Protection Agency, Office of Research and DevelopmentJ'echnological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
50
Mauro, M. "Construction of Deep Barrier Walls for Waste Containment." Environmental Restoration Conference , 1995.
51
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VERTICAL BARRIERS
and are typically placed at depths less than 15 meters (50 ft),51 although slurry walls up
to 200 feet in depth have been successfully constructed.52
Grout curtains are narrow, vertical, grout walls installed in the ground. They
are constructed by pressure-injecting grout directly into the soil at closely spaced
intervals around the waste site. The spacing is selected so that each "pillar" of grout
intersects the next, thus forming a continuous wall or curtain.53 Grout curtains may be
used up-gradient of the contaminated area, to prevent clean water from migrating
through waste, or down-gradient, to limit migration of contaminants. Grout curtains
are generally used at shallow depths (30 to 40 ft maximum depth).54 Typical grouting
materials include hydraulic cements, clays, bentonite and silicates. However, these
materials may crack or may not be durable or chemically compatible. Polymer grouts
are used for barrier applications because they are impermeable to gases and liquids and
resist radiation, as well as acidic and alkaline environments. A barrier that is currently
undergoing field testing consists of a conventional cement grout curtain with a thin
lining of polymer grout. Close-coupled barriers such as this can be used for a wide
range of waste in addition to radionuclides, and in a variety geohydrologic
conditions.55
U.S. Department of Defense, Environmental Technology Transfer Committeeftemediation Technologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
52
Mauro, M. "Construction of Deep Barrier Walls for Waste Containment." Environmental Restoration Conference , 1995.
U.S. Environmental Protection Agency, Office of Research and DevelopmentTechnological Approaches to the Cleanup of
Radiologicalfy Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
Oak Ridge National Laboratory, Oak Ridge National Laboratory Technology Logic Diagrams, Volume technology Evaluation
Data Sheets, Part B, Dismantlement - Remedial Action ORNL/M-2751/V3/PI.B, September 1993.
55
Heiser, J. "Demonstration of Close-Coupled Barriers for Sub-Surface Containment of Buried Waste" Environmental Restoration
Conference, 1995.
52
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VERTICAL BARRIERS
M embran
Compacted
Soil Contaminated wit
Radioactive Waste
Clean
Soil
Confining Layer
Exhibit 2-10: Vertical Barriers
Target Contaminant Groups
Vertical barriers provide subsurface containment for a wide variety of waste,
including radionuclides, metals, and organics.
Technology Operating Characteristics
Exhibit 2-11 summarizes the operating characteristics of vertical barriers.
Exhibit 2-11: Technical Characteristics of Vertical Barriers
Characteristic
Description
Destruction and
Removal Efficiencies
(DREs)
Not applicable
53
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VERTICAL BARRIERS
Exhibit 2-11: Technical Characteristics of Vertical Barriers (Cont.)
Characteristic Description
Emissions: Gaseous
and Particulate
Costs: Capital and
O&M
Reliability
Process Time
Applicable Media
Pretreatment/Site
Requirements
Type and Quantity of
Residuals
Disposal Needs and
Options
Post-Treatment
Conditions
Ability to Monitor
Effectiveness
Not applicable
Most costs are capital; O&M costs involve monitoring and
mitigation. Slurry walls range from $540 to $750 per square meter.
56 Grout curtains range from $30 to $40 per square foot. 57
Reliable upon implementation, however vertical barriers often
deteriorate over time.
Not applicable. The barrier is effective upon implementation.
Soil, sediment, leachates, bulk waste, and groundwater
Detailed knowledge of soil characteristics and site geology.
Not applicable
Not applicable
Regulatory compliance procedures would apply (e.g. monitoring
and mitigation).
Institutional controls, such as deed, site access, and land use
restrictions, are usually required.
Can monitor the contamination level of nearby groundwater and
the integrity of the vertical barriers.
Site Considerations
Successful installation of a vertical barrier requires detailed knowledge of the
soil's physical and chemical characteristics and the subsurface geology. Many
common chemical (particularly organic) contaminants that may be present at
radioactive waste sites can destroy certain grout materials or prevent them from
setting. Therefore, characterization of the site waste, leachate, and barrier material
chemistry, as well as compatibility testing of the barrier material with the likely
TJ.S. Department of Defense, Environmental Technology Transfer Committeeftemediation Technologies Screening Matrix and
Reference Guide, October 1994.
Oak Ridge National Laboratory, Oak Ridge National Laboratory Technology Logic Diagrams, Volume technology Evaluation
Data Sheets, PartB, Dismantlement - Remedial Action ORNL/M-2751/V3/PI.B, September 1993.
54
-------
VERTICAL BARRIERS
chemical environment, is required.58 Other site conditions that may also affect the
integrity of the barrier include climate, which influences wet-dry cycling, and tectonic
activity.
2.4.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
In general, vertical barriers protect human health and the environment by
reducing exposure pathways due to the migration of contaminants. Their effectiveness
largely depends on the presence of a confining layer of clay or rock, into which the
vertical barrier is keyed. Without a confining layer, the vertical barrier will not form
an effective barrier because groundwater will flow under the barrier. Possible
deterioration of the barrier walls, caused by chemicals in the waste (e.g., organic
compounds) and wet-dry cycling in soils, could cause leaching of contaminated
groundwater into the surrounding environment.59
During trench excavation, if applicable, nearby populations and site workers
are at risk of exposure to radioactive contaminants due to fugitive dust and gas
emissions. To mitigate these hazards, fugitive dust control techniques and limiting
operations to favorable meteorological conditions should be practiced.
Compliance with ARARs
Compliance with ARARs must be determined on a site-specific basis. At DOE
facilities, vertical barriers must comply with performance criteria outlined in DOE
Order 5820.2A.
Long-Term Effectiveness
Vertical barriers have been used for decades as long-term solutions for
controlling seepage of contaminated groundwater. However, vertical barriers do
nothing to eliminate the toxicity associated with radionuclides or any other
contaminants they simply confine the contaminants to the site, thereby inhibiting
contaminant migration. Slurry walls and grout curtains both have the potential to
degrade or deteriorate over time due to certain chemicals contained in the waste and
Siskind, B. and Heiser, J. "Regulatory Issues and Assumptions Associated with Barriers in the Vadose Zone Surrounding Buried
Waste." Brookhaven National Laboratory, 1993.
U.S. Environmental Protection Agency, Office of Research and DevelopmentJ'echnological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
55
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VERTICAL BARRIERS
various weathering processes. In contaminated environments, their long-term
effectiveness is very dependent on contaminant types and concentrations. The long-
term effectiveness of vertical barriers may be improved through use of such materials
as HDPE membranes and polymer grouts, which have increased chemical resistance
and reduced hydraulic conductivity.
Monitoring the barrier(s) and the surrounding groundwater is necessary to
ensure long-term effectiveness. Technologies that help monitor subsurface barriers
include sensors placed within and adjacent to barriers to detect significant changes in
moisture content, and the use of gaseous tracers to locate breaches.60
Reduction of Radiotoxicity. Mobility, or Volume
Vertical barriers do not reduce the radiotoxicity or volume of contaminated
material, although they reduce the horizontal mobility of contaminants in soil or
groundwater plumes.
Short-Term Effectiveness
As soon as they are in place, vertical barriers can significantly reduce exposure
risks. However, it is difficult to obtain truly low permeabilities in grout curtains that
are constructed of nonconsolidated materials. Also, many chemical contaminants can
prevent certain grout materials from setting.61 These factors may limit the
effectiveness of grout curtains.
Implementability
Vertical barriers in soil and soil-like materials are relatively easy to install.62
Because slurry walls have been used for decades, the equipment and methodology are
readily available and well-known. However, the process of designing the proper mix
of wall materials to contain specific contaminants is less well developed. Excavation
and backfilling of the slurry trench is critical and requires experienced contractors.63
60
MWLID Sandia/Westinghouse Hanford, "Verification of Sub-Surface Barriers using Time Domain Reflectometry (TDR) with
Waveguides" 1994.
61
U.S. Environmental Protection Agency, Office of Research and DevelopmentTechnological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
62Ibid.
63
U.S. Department of Defense, Environmental Technology Transfer Committeefietnediation Technologies Screening Matrix and
Reference Guide, October 1994.
56
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Preceeding Page Blank
VERTICAL BARRIERS
Cost
Vertical barrier costs are mostly capital costs; operation and maintenance costs
include monitoring and mitigation. Estimated costs for the design and installation of a
standard slurry wall in soft to medium soil range from $540 to $750 per square meter.
The use of an HDPE membrane in a slurry wall will increase the capital cost. Grout
curtains with conventional materials generally cost between $30 to $40 per square
foot. Use of a close-coupled barrier with a polymer grout lining increases the capital
cost. These costs do not include variable costs required for chemical and radiological
analyses, feasibility, or compatibility testing. Testing costs depend heavily on site-
specific factors. Other site-specific factors that significantly impact the final cost of
slurry wall or grout curtain installation include:
type, activity, and distribution of contaminants;
depth, length, and width of the wall;
geological and hydrological characteristics;
distance from the source of materials and equipment;
requirements for wall protection and maintenance.64
2.4.3 Summary
A vertical barrier is a containment technology used to help confine radioactive
waste and any contaminated groundwater that might otherwise flow from the site.
Two types of vertical barriers used to contain radioactive waste are slurry walls and
grout curtains. Both are often used in conjunction with capping to provide more
thorough waste containment. Vertical barriers are effective upon implementation.
Costs of this technology depend on the barrier materials selected and site-specific
conditions. Although installing vertical barriers requires expertise, the process is not
complex and materials are readily available.
The following factors may limit the applicability and effectiveness of using
vertical barriers:
vertical barriers must reach down to an impermeable horizontal barrier
to effectively impede groundwater flow;
thorough characterization of the subsurface is required because settling
or unstable ground can limit effectiveness;
Oak Ridge National Laboratory, Oak Ridge National Laboratory Technology Logic Diagrams, Volume technology Evaluation
Data Sheets, PartB, Dismantlement - Remedial Action ORNL/M-2751/V3/PI.B, September 1993.
58
-------
VERTICAL BARRIERS
conventional barrier materials do not withstand attack by strong acids,
bases, salt solutions, and some organic chemicals;
vertical barriers can degrade or deteriorate over time.
Exhibit 2-12 summarizes the data and analyses presented in this profile and can
be used for technology comparison.
Exhibit 2-12: NCP Criteria for Vertical Barriers
NCP Criterion
Evaluation
Performance Data
Overall Protectiveness
Eliminates many risks due to
migration by containing the
waste.
Successfully diverts uncontaminated
groundwater flow.
Useful for reducing contaminant
migration.
Compliance with
ARARs
Compliance with soil and
groundwater ARARs must
be determined on a site-
specific basis.
DOE sites must comply with
performance criteria in Order
5820.2A.
Reduction of
Radiotoxicity,
Mobility, or Volume
Reduces mobility, but not
radiotoxicity or volume, of
contaminated media.
Process does not remove or reduce
contaminants.
Reduces lateral migration of
contaminants.
Long-Term
Effectiveness and
Permanence
Leaves untreated
contaminated media in place.
Potentially ineffective in the
long-term due to potential
barrier deterioration.
Depends on contaminant types and
concentrations.
Possibility of barrier deterioration
over the long-term. Possible site
conditions that could affect barrier
integrity include climate and tectonic
activity.
Short-Term
Effectiveness
Potential risks to site
workers if extensive
excavation is required.
The effectiveness of grout curtains
may be reduced if constructed of non-
consolidated materials or in the
presence of certain chemicals.65
U.S. Environmental Protection Agency, Office of Research and Developmenifechnological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
59
-------
VERTICAL BARRIERS
Exhibit 2-12: NCP Criteria for Vertical Barriers (Cont.)
NCP Criterion
Evaluation
Performance Data
Implementability
Relatively easy to
implement.
Equipment and methodology
are well-known and readily
available.
Excavation and backfilling slurry
trench requires experienced
contractors.
Thorough characterization of waste
type, topography, soil condition,
thermal conductivity, and
groundwater movement is important.
Cost
Most costs are capital; O&M
costs include monitoring and
mitigation.
Capital cost is dependent on
the type of barriers materials
selected.
Slurry walls: $540 to $750 per square
meter.
Grout curtains: $30 to $40 per square
foot.
HDPE membranes or polymer grouts
increases cost.
60
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SOLIDIFICATION/STABILIZATION
Solidification/Stabilization technologies reduce the mobility of hazardous and
radioactive contaminants in the environment through both physical and chemical processes.
Stabilization seeks to trap contaminants within their "host" medium (i.e., the soil, sand, and/or
building materials that contain them), by inducing chemical reactions between the stabilizing
agent and contaminants, thus reducing their mobility. Solidification encapsulates the waste in
a monolithic solid of high-structural integrity. Solidification does not involve chemical
interaction between the contaminants and the solidification agents but are bonded
mechanically. Solidification and stabilization techniques are often used together. The intent
of solidification and/or stabilization processes would be to limit the spread of radioactive
material and to trap and contain radon within the monolithic solid. While the contaminants
would not be removed and would remain radioactive, the mobility of the contaminants would
be eliminated or reduced.
Solidification/Stabilization has been implemented full-scale and may be employed in-
situ or ex-situ. In-situ techniques use auger/caisson systems and injector head systems to
apply agents to in-situ soils. Ex-situ techniques differ from in-situ techniques because ex-situ
processes involve digging up the materials and machine-mixing them with the solidifying
agent instead of injecting the agent to the materials in place. Ex-situ processes typically
require disposal of the resultant materials. In-situ and ex-situ techniques can be used alone or
combined with other treatment and disposal methods to yield a product or material suitable
for land disposal or, in other cases, that can be applied to beneficial use. Both techniques
have been used as final and interim remedial measures.
This profile presents:
Cement solidification/stabilization (S/S)
Chemical solidification/stabilization (S/S)
There may be one or more sub-options applicable to each process.
The flow diagrams in Exhibit 2-13 and Exhibit 2-14 illustrate the general process
involved with ex-situ and in-situ Solidification/Stabilization technologies respectively.
-------
SOLIDIFICA TION/STABILIZA TION
H opper w ith
Even Feeder
^
^
Weight
Feeder
Soil Contaminated
with Radioactive
Waste
H om ogenize
Pug Mill
Auger
Dry Reagent
Feeder
Solidified Product
Containing
Radioactive Materials
Exhibit 2-13: Ex-Situ Solidification/Stabilization
> Stabilized/Solidified Media
Solidification/Stabilization^
Binding Agent(s)
^Residuals
62
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CEMENT SOLIDIFICA TION/STABILIZA TION
Exhibit 2-14: In-Situ Solidification/Stabilization
2.5 CEMENT
SOLIDIFCATION/STABILIZATION
2.5.1 Technology Characterization
Description
Cement solidification/stabilization (S/S) processes involve the addition of
cement or a cement-based mixture which limits the solubility or mobility of the waste
constituents. These techniques are accomplished in-situ by either injecting a cement-
based agent into the contaminated materials, or ex-situ by excavating the materials,
machine-mixing them with a cement-based agent, and depositing the solidified mass in
a designated area. The goal of the S/S process is to limit the spread of radioactive
material via leaching, and to trap and contain radon within a densified soil mass. This
process does not remove or inactivate contaminants, but eliminates or reduces
contaminant mobility.
The end product resulting from the solidification process is a monolithic block
of waste with high structural integrity. Types of solidifying/stabilizing agents include
the following: Portland; gypsum; modified sulfur cement, consisting of elemental
sulfur and hydrocarbon polymers; and grout, consisting of cement and other dry
materials, such as acceptable fly ash or blast furnace slag. Processes utilizing
modified sulfur cement are typically performed ex-situ.
Target Contaminant Groups
Properly implemented, cement S/S can apply to most contaminants, including
all classes of radioactive waste, organics, inorganics, heavy metals, and mixed waste.
This technology, however, may have limited effectiveness against SVOCs and
pesticides. In general, in-situ cement S/S can be considered at any site from which
radioactive waste cannot be removed. Type I Portland cement-based grout is
commonly used to solidify most hazardous waste, while Types II and V Portland
cement-based grouts are used for waste containing sulfates or sulfites.
Technology Operating Characteristics
Cement S/S could be considered for a variety of situations but is best suited to
highly porous, coarse-grained, low-level radioactive waste in permeable matrices.
63
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CEMENT SOLIDIFICA TION/STABILIZA TION
Exhibit 2-15 summarizes the operating characteristics of cement
solidification/stabilization.
Exhibit 2-15: Technical Characteristics of Cement
Solidification/Stabilization (S/S)
Characteristic
Description
Destruction and
Removal Efficiencies
(DREs)
Emissions: Gaseous
and Particulate
Unconfined
Compressive Strength
Costs: Capital and
O&M
Reliability
Process Time
Applicable Media
Not applicable
If necessary, a hood can be placed over the system to capture
volatile contaminants released during the injection process.
Strengths for modified sulfur cement twice those of Portland
cements have been achieved. Strengths for sulfur cement are in
the range of 27.6 MPA (4000 psi).66
For ex-situ solidification/stabilization processes, overall costs from
more than a dozen vendors are under $ 1 00 per ton, including
excavation. The in-situ soil mixing/auger techniques average $40
- $60 per cubic yard for shallow applications and $150 - $250 per
cubic yard for deeper applications. 67
The long-term effects of weathering, groundwater infiltration, and
physical disturbance cannot be predicted accurately.
The shallow in-situ soil mixing technique for in-situ applications
processes 40 - 80 tons per hour on average, and the deep soil
mixing technique averages 20 - 50 tons per hour. 6S
Soils, sediments, sludges, refuse
U.S. Environmental Protection Agency, Solid Waste and Emergency Response, Innovative Site Remediation Technology,
Solidification/Stabilization, Volume 4, EPA 542-B-94-001, June 1994.
U.S. Department of Defense, Environmental Technology Transfer Committeeftemediation Technologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
68
64
-------
CEMENT SOLIDIFICA TION/STABILIZA TION
Exhibit 2-15: Technical Characteristics of Cement
Solidification/Stabilization (S/S) (Cont.)
Characteristic
Pre-Treatment/Site
Requirements
Description
Before in-situ cement solidification/stabilization is applied at any
site, extensive laboratory studies should be conducted to
incorporate performance criteria, process criteria, and site-specific
criteria.69 Laboratory studies also can address design issues such as
achieving a specific permeability, minimizing volume increase, or
eliminating surface berms.
Prior to modified sulfur cement S/S, the waste should be dried.70
Type and Quantity of
Residuals
Radioactive materials are left in place. No residuals are produced.
Disposal Needs and
Options
The solidified/stabilized mass remains in place when utilizing the
in-situ approach. Excavated and mixed mass can be contained or
buried on or off site.
Post-Treatment
Conditions
With the in-situ approach or on site burial, all waste will remain at
the site. Institutional and engineering controls will most likely be
required. Ex-situ solidification may facilitate the transportation of
off site disposal of radioactive contaminants with the use of
containers, especially where volume reduction or extraction
techniques have been applied, previously.
Ability to Monitor
Effectiveness
The level of performance for stabilization process is measured by
the amount of constituents that can be leached from the stabilized
material. Two techniques recognized by USEPA as measure of
leachability are the Extraction Process (EP) Toxicity Test and the
Toxicity Characteristic Leaching Procedure (TCLP).71
U.S. Environmental Protection Agency, Office of Research and Deve\opment{lpproaches for the Remediation of Federal Facility
Sites Contaminated with Explosive or Radioactive Waste, EPA/625/R-93/013, September 1993.
\J.S. Environmental Protection Agency, Solid Waste and Emergency Response, Innovative Site Remediation Technology,
Solidification/Stabilization, Volume 4, EPA 542-B-94-001, June 1994.
U.S. Environmental Protection Agency, Office of Emergency and Remedial ResponseSummary of Treatment Technology
Effectiveness for Contaminated Soil, PB92-963351, June 1990.
65
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CEMENT SOLIDIFICA TION/STABILIZA TION
Site Considerations
The in-situ method also may not be suitable if masses are thin, discontinuous,
and at or near the surface. Special concerns may be posed by other types of hazardous
waste (e.g., organic chemicals) that may interfere with solidifying the radioactive
waste. Some factors include inorganic acids that will decrease durability for Portland
Type I cement; chlorinated organics that may increase set time and decrease durability
of cement if concentration is too high; and oil and grease that will decrease unconfined
compressive strength.72
In-situ S/S may not be suitable for some sites because gamma radiation might
not be reduced sufficiently, and because maintenance of utilities would be difficult.
Consideration must also be given to any debris such as barrels, scrap metals, and wood
pieces that may interfere with the solidification process. Environmental risks related
to drilling through the buried waste exist, especially if liquid-filled drums are pierced
and their contents are spilled. The fluid inside the containers may contain material
detrimental to the cementation process. If whole drums can be located, removal
should be considered to eliminate risk of puncture.
Several soil characteristics influence whether the technology will contain the
waste effectively. These characteristics include void volume, which determines how
much grout can be injected into the site; soil pore size, determines the size of the
cement particles that can be injected; and permeability of the surrounding, which
determines whether water will flow preferentially around the solidified mass.
2.5.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
Although this technology does not reduce the toxicity or volume of
contaminants, if successful, it has been proven to greatly reduce the mobility, thus
protecting human health and the environment by reducing risk of exposure. However,
process control is relatively poor and it is difficult to verify that the monolith actually
contains the waste. Since cement solidification may not shield or eliminate radiation
effects, some form of capping or shielding may be appropriate.
U.S. Environmental Protection Agency, Office of Emergency and Remedial Response$olification/Stabilization of Organics and
Inorganics, EPA/540/S-92/015, May 1993.
66
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CEMENT SOLIDIFICA TION/STABILIZA TION
Compliance with ARARs
The treatment must result in residual soil levels that comply with NRC
requirements and RCRA LDRs. Since no material is actually removed from the site
during in-situ solidification, the site must be appropriate for leaving the material on
site in a less mobile form. Compliance with other ARARs need to be determined on a
site-specific basis.
Long-Term Effectiveness
Leach resistance of some solidified/stabilized waste is relatively high.73
However, the long-term effects of weathering, groundwater infiltration, and physical
disturbance associated with uncontrolled future land use can significantly affect the
integrity of the stabilized mass and contaminant mobility in ways that cannot be
predicted.74
Reduction of Radiotoxicity. Mobility, or Volume
While solidification and stabilization reduce the mobility of a contaminant, the
volume of the waste increases, and there is only an incidental effect on toxicity. In-
situ processes have demonstrated the capability to reduce the mobility of contaminated
waste by greater than 95 percent.75
Short-Term Effectiveness
In-situ processes result in risk of exposure since injection is performed
vertically over the waste. During ex-situ processes there are potential risks of
exposure to workers during the excavation, mixing, and handling of waste. Also,
fugitive dust emissions resulting from excavation could potentially expose workers
and the surrounding community.
TJ.S. Department of Defense, Environmental Technology Transfer CommitteeRemediation Technologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
67
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CEMENT SOLIDIFICA TION/STABILIZA TION
Implementability
Cement S/S is well demonstrated and easy to implement. Most reagents and
additives are generally widely available and relatively inexpensive industrial
commodities. However, detailed characterization of the site and the waste matrix is
required to determine the suitability ofin-situ processes.
Cost
Costs can vary based on specific soil conditions, contaminants, and availability
of solidification agents. Also, ex-situ costs for transportation and offsite disposal of
the solidified material play a role in the overall cost. Low costs may reflect in-situ
mixing techniques and high costs may reflect in-drum mixing techniques.
2.5.3 Summary
The following factors may limit the applicability and effectiveness of cement S/S:
In-situ Techniques
Depth of contaminants may limit some types of application processes.
Future usage of the site may "weather" the materials and affect ability to
maintain immobilization of contaminants.
Some processes result in significant increase in volume (up to double
the original volume).
Certain waste are incompatible with variations of this process.
Treatability studies are generally required. Reagent delivery and
effective mixing are more difficult than for ex-situ applications.
Like all in-situ treatments, confirmatory sampling can be more difficult
than for ex-situ treatments.76
Ex-situ Techniques
Environmental conditions may affect the long-term immobilization of
contaminants.
Some processes result in a significant increase in volume (up to double
the original volume).
68
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CEMENT SOLIDIFICA TION/STABILIZA TION
Certain waste are incompatible with different processes. Treatability
studies are generally required.
VOCs are generally not immobilized.
Long-term effectiveness has not been demonstrated for many
contaminant/process combinations.77
Solidification/stabilization technologies are well demonstrated, can be applied to the
most common site and waste types, require conventional materials handling equipment, and
are available competitively from a number of vendors.
Exhibit 2-16 summarizes the data and analyses presented in this profile and can be
used for technology comparison.
Exhibit 2-16: NCP Criteria for Cement Solidification/Stabilization (S/S)
NCP Criterion
Overall Protectiveness
Evaluation
Limited overall
protectiveness at site;
however, does prevent
migration of
contaminants to
exposure pathways.
Performance Data
May not shield or eliminate radiation
effects.
Compliance with
ARARs
Determined on a site-
specific basis.
Determined on a site-specific basis.
Reduction of
Radiotoxicity, Mobility,
or Volume
Does not reduce toxicity
or volume; does reduce
mobility.
In-situ processes do not involve removal or
destruction of contaminants, however,
solidification may be able to reduce the
release of radon and associated
radioactivity to acceptable levels at the
waste site without removal of materials for
off site containment.
Long-Term
Effectiveness and
Permanence
Technology is not
proven in the long-term.
Cement S/S is acceptable for reducing the
leachability of radionuclides or heavy
metals. However, the long-term effects of
weathering, groundwater infiltration, and
physical disturbance cannot be predicted.
Ibid.
69
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CEMENT SOLIDIFICA TION/STABILIZA TION
Exhibit 2-16: NCP Criteria for Cement Solidification/Stabilization (S/S) (Cont.)
NCP Criterion
Evaluation
Performance Data
Short-Term
Effectiveness
Risk exists to both
workers and/or the
nearby community
during solidification
processes.
Fugitive dust generation from excavation
and handling of waste during ex-situ
processes poses a health and safety risk to
workers and nearby communities. Risk to
workers also results from drilling during
in-situ techniques.
Implementability
Easy to implement.
Based onsite circumstances, technology
may have to be combined with other
treatment methods (e.g., use of soil cover
or cap). Sufficient mixing must occur
between soil and grouting materials to be
effective.
Cost
Relatively low cost
technology.
Documented costs range from $40 - $250
per cubic yard. Availability of
solidification agent selected and, for ex-situ
processes, transportation and disposal costs
will affect the overall cost.
70
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CHEMICAL SOLIDIFICA TION/STABILIZA TION
2.6 CHEMICAL
SOLIDIFCATION/STABILIZATION
2.6.1 Technology Characterization
Description
Chemical Solidification/Stabilization (S/S) involves adding chemical reagents
to waste in order to limit the waste solubility and mobility. It is accomplished either
in-situ, by injecting a solidifying/stabilizing agent into contaminated materials, or ex-
situ, by excavating and machine-mixing the materials with the solidifying/stabilizing
agent and then placing the solidified soil in containers or burying it on site. Onsite
burial of the solidified soil requires a soil cover sufficiently thick to absorb gamma
radiation. Chemical S/S agents include thermoplastic polymers (asphalt bitumen,
paraffin, polyethylene), thermosetting polymers (vinyl ester monomers, urea
formaldehyde, epoxy polymers), and other proprietary additives. Chemical grouts can
also be used as S/S agents, however little information is available on this process.
The chemical S/S process limits the spread of radioactive material via leaching,
and traps and contains radon within a dense soil mass. Rather than inactivate
contaminants, this process eliminates or reduces the contaminants' mobility.
Target Contaminant Groups
Properly implemented, chemical S/S can apply to many contaminants,
including all classes of radioactive waste, organics, inorganics, heavy metals, and
mixed waste. This process may not be effective on other organics (e.g., SVOCs and
pesticides) that can inhibit the chemical bonding of stabilizers or the mechanical
bonding of solidifying agents.
Technology Operating Characteristics
Exhibit 2-17 summarizes the operating characteristics of chemical
solidification/stabilization.
71
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CHEMICAL SOLIDIFICA TION/STABILIZA TION
Exhibit 2-17: Technical Characteristics of Chemical
Solidification/Stabilization
Characteristic
Description
Destruction and Removal
Efficiencies (DREs)
TCLP Results
Unconfined Compressive
Strength
Emissions: Gaseous and
Particulate
Costs: Capital and O&M
Reliability
Not applicable
Poor for organic waste constituents. Excellent for metals.
220 to 1570psi78
390 to 860 psi79
Volatile compounds can be released if mechanical mixing is
involved.80
For ex-situ processes, overall costs are under $100 per ton,
including excavation. The in-situ soil mixing/auger techniques
average $40 - $60 per cubic yard for shallow applications and $150
- $250 per cubic yard for deeper applications. Most reagents and
additives are also widely available, relatively inexpensive industrial
commodities.81
The reliability of most chemical stabilizing agents has yet to be
fully determined. Some testing has been performed on polyethylene
waste.
78U.S. Environmental Protection Agency, EPA/540/M5/89/001, 1989.
'ibid.
''ibid.
79
81
U.S. Department of Defense, Environmental Technology Transfer CommiUe&Remediation Technologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
72
-------
CHEMICAL SOLIDIFICA TION/STABILIZA TION
Exhibit 2-17: Technical Characteristics of Chemical
Solidification/Stabilization (Cont.)
Characteristic
Description
Process Time
Applicable Media
Pretreatment/Site
Requirements
Disposal Needs and
Options
Post-Treatment Conditions
Ability to Monitor
Effectiveness
A typical full-scale polyethylene extruder can process 900
kilograms of mixed material per hour consisting of 30% binder and
70% waste. The extruded material takes only a few hours to cool
and to set. 82
The shallow soil mixing technique for in-situ applications processes
40 to 80 tons per hour on average; the deep soil mixing technique
averages 20 to 50 tons per hour. 83
Soils, sediments, sludges, refuse
No pretreatment is required. However, testing must be performed
to assess the effectiveness of the chemical mix with the
contaminant.
Solidified/stabilized mass remains in place with in-situ approach.
Excavated and mixed mass must be contained or buried on- or off-
site.
With the in-situ approach or on-site burial, all waste will remain at
the site. Institutional controls will probably be required.
Rigorous verification involves digging up the perimeter of the
stabilized/solidified area. Additionally, S/S does not lend itself to
waste retrieval.
Site Considerations
While chemical S/S can be used in a variety of situations, it is better suited to
fine-grained soil with small pores. The in-situ method may not be suitable for
residential sites because gamma radiation may not be sufficiently reduced, and
because maintenance of utilities would be difficult. The in-situ method also may not
be suitable if masses are thin, discontinuous, and at or near the surface. Special
concerns can be encountered by the presence of other types of hazardous waste that
U. S. Environmental Protection Agency, Office of Research and Deve\opment£pproaches for the Remediation of Federal
Facility Sites Contaminated with Explosive or Radioactive Waste, EPA/625/R-93/013, September 1993.
U.S. Department of Defense, Environmental Technology Transfer Committeeftemediation Technologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
73
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CHEMICAL SOLIDIFICA TION/STABILIZA TION
may interfere with the solidification process organic chemicals could be particularly
troublesome.
2.6.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
This technology provides protectiveness by greatly reducing the mobility of
radioactive materials. The solidified mass, under proper conditions, will remain intact
for long periods of time, although it may not shield or eliminate radiation effects.
Some form of capping or shielding may therefore be appropriate.
Compliance with ARARs
During in-situ chemical S/S, no material is actually removed from the site. The
site must be appropriate for leaving the material on site in a less mobile form. This
technology generally meets RCRA LDR requirements for metals, however organics in
the waste may inhibit cementation and chemical bonding processes and result in non-
compliance.
Long-Term Effectiveness
Radioactive materials will remain onsite or wherever the solidified mass is
disposed of. The S/S process itself may not provide adequate shielding from all types
of radiation; covering or capping may be required. S/S should greatly reduce or
eliminate the threat of groundwater contamination or other migration, although long-
term site maintenance and institutional controls would be required. The long-term
effects of weathering, groundwater infiltration, and physical disturbance associated
with uncontrolled future land use can significantly and unpredictably affect the
integrity of the stabilized mass.84
Research is underway on the viability and reliability of most chemical
stabilizing agents. Water immersion and temperature fluctuation tests on polyethylene
waste forms showed no significant changes in compressive strength. In addition,
o
exposure tests of radiation up to 10 rad increased cross-linking in the waste forms,
S4ib,d.
74
-------
CHEMICAL SOLIDIFICA TION/STABILIZA TION
thus were stronger, more stable under thermal cycling, more resistant to solvents, and
more resistant to leaching.85
Reduction of Radiotoxicity. Mobility, or Volume
While S/S reduces contaminant mobility, the volume of the waste increases;
there is only an incidental effect on toxicity.
Short-Term Effectiveness
Potential risks of exposure to workers exist during waste handling. Also,
fugitive dust emissions resulting from excavation could expose workers and the
surrounding community to contaminants. Transportation of waste to offsite disposal
facility for ex-situ treatment also increases exposure risks to workers and community.
Implementability
This process is generally easy to implement (e.g., uses conventional materials
and widely available equipment).
Cost
Costs vary. In-situ chemical processes usually cost less than ex-situ processes.
Nonetheless, the range of costs is relatively low compared to other technologies.
2.6.3 Summary
Although chemical S/S may effectively reduce the mobility of radioactive
contaminants, it may not affect volume or toxicity. It is applicable to the most
common site and waste types, uses conventional materials handling equipment, and is
widely available. This technology usually requires capping or covering, engineering
controls, and/or institutional controls.
Factors that may limit the applicability and effectiveness of in-situ and ex-situ
S/S include:
In-situ techniques
depth of contaminants may limit some types of application;
U.S. Environmental Protection Agency, Office of Research and Development^Lpproaches for the Remediation of Federal Facility
Sites Contaminated with Explosive or Radioactive Waste, EPA/625/R-93/013, September 1993.
75
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CHEMICAL SOLIDIFICA TION/STABILIZA TION
future site use may "weather" the materials and affect their ability to
immobilize contaminants;
some processes result in a significant volume increase (up to double the
original);
certain waste are incompatible with process variations treatability
studies are generally required; reagent delivery and effective mixing are
more difficult than for ex-situ applications;
confirmatory sampling can be more difficult than for ex-situ
treatments.86
Ex-situ techniques
environmental conditions may affect long-term contaminant immobility;
some processes result in a significant volume increase (up to double the
original);
certain waste are incompatible with different processes treatability
studies are generally required;
VOCs are generally not immobilized;
long-term effectiveness has not been demonstrated for many
contaminant/process reagent combinations.87
Additionally, a major factor driving the selection process beyond basic waste
compatibility is the availability of suitable reagents. Chemical S/S processes require
that potentially large volumes of bulk reagents and additives be transported to project
sites. Transportation costs may therefore dominate project budgets and may quickly
become uneconomical in cases where materials are not locally available.88
Exhibit 2-18 summarizes the data and analyses presented in this profile and can
be used for technology comparison.
U.S. Department of Defense, Environmental Technology Transfer Committeeftemediation Technologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
S7lbid.
sslbid.
76
-------
CHEMICAL SOLIDIFICA TION/STABILIZA TION
Exhibit 2-18: NCP Criteria for Chemical Solidification/Stabilization
NCP Criterion
Evaluation
Performance Data
Overall
Protectiveness
Limited overall
protectiveness at site;
however, does prevent
migration of contaminants
to exposure pathways.
May not shield or eliminate
radiation effects.
Effective in reducing
leachability of radioactive
material. Some organic
constituents of mixed waste
can reduce effectiveness.
Exhibit 2-18: NCP Criteria for Chemical Solidification/Stabilization
(Cont.)
NCP Criterion
Evaluation
Performance Data
Compliance with
ARARs
Determined on a site-
specific basis.
Determined on a site-
specific basis.
Reduction of
Radiotoxicity,
Mobility, or Volume
Does not reduce toxicity or
volume of contaminants;
reduces mobility.
Process can increase
volume of media after
solidification.
Does not remove or destroy
contaminants.
Long-Term
Effectiveness and
Permanence
Radioactive materials
remain on site or wherever
the solidified mass is
disposed of.
Process itself does not
provide adequate shielding
from all types of radiation.
Process leads to effective
long-term reduction in
exposure risks via
groundwater.
Long-term site maintenance
of the site and institutional
controls may be required.
Process can greatly reduce
the threat of groundwater
contaminants.
TCLP results are excellent
for metal and radionuclides;
poor for organics.
77
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CHEMICAL SOLIDIFICA TION/STABILIZA TION
Exhibit 2-18: NCP Criteria for Chemical Solidification/Stabilization
(Cont.)
NCP Criterion
Evaluation
Performance Data
Short-Term
Effectiveness
Excavation of waste can
expose site personnel.
Process can be completed
within short timeframe.
Transportation for off-site
disposal can increase risk to
community.
Volatile contaminants can
be released during mixing.
1800 pounds per hour for
polyethylene process; only
a few hours for cooling and
setting of mass.
Ex-situ process may require
offsite disposal of solidified
mass.
Implementability
Easy to implement.
Many chemical stabilizing
agents need further testing
and development.
Requires soil cover or cap
of sufficient thickness.
Optimal conditions for
many chemical agents not
determined.
Cost
Costs depend on the
availability and/or
transportation of the
solidifying agents.
Costs range from $40 to
$250 per ton.
78
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CHEMICAL SEPARATION
CHEMICAL SEPARATION
TECHNOLOGIES
Chemical separation involving the use of solvent/chemical extraction separates and
concentrates radioactive contaminants from soil. The process residuals require further
treatment, storage, or disposal. Radionuclide contaminants can be extracted by using
inorganic salts, mineral acids, complexing agents, or organic solvents. There are notable
differences in the extractability rates of each agent due to the types and concentrations of
contaminants as well as varying conditions within the method. The implementability of this
technology is controlled by site-specific factors and their applicability must be determined on
a site by site basis.
79
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Preceeding Page Blank
SOLVENT/CHEMICAL EXTRACTION
2.7 SOLVENT/CHEMICAL
EXTRACTION
2.7.1 Technology Characterization
Description
Solvent/chemical extraction is an ex-situ chemical separation technology that
separates hazardous contaminants from soils, sludges, and sediments to reduce the
volume of hazardous waste that must be treated. Solvent/chemical extraction involves
excavating and transferring soil to equipment that mixes the soil with a solvent. This
equipment may handle contaminated soil either in batches, for dry soil, or as a
continuous flow, for pumpable waste. When the hazardous contaminants have been
sufficiently extracted, the solvent is separated from the soil and distilled in an
evaporator or column. Distilled vapor consists of relatively pure solvent that is
recycled into the extraction process; the liquid residue, which contains concentrated
contaminants, undergoes further treatment or disposal (see Exhibit 2-19). While not
all radionuclides and solvent will be removed from the contaminated soil, if it is
sufficiently clean it can be returned to its original location. Otherwise, it may require
separate storage or disposal.
Solvent/chemical extraction has been used extensively to extract uranium from
mineral ores. However, using this technology to treat soils contaminated with
radionuclides or mixed waste requires further development.89 Solvents that could be
used to remove radioactive waste include: complexing agents, such as EDTA
(ethylenediamine-tetraacetic acid); inorganic salts; organic solvents; and mineral acids,
such as sulfuric, hydrochloric, or nitric acid. Each solvent's effectiveness in removing
different contaminants depends on concentrations, pH, and solubility.90'91
While it can sometimes be used as a stand-alone technology, solvent/chemical
extraction is commonly used with other technologies, such as
"Ibid.
\I.S. Environmental Protection Agency, Office of Research and DevelopmentJ'echnological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
U.S. Department of Energy, Office of Technology Development£$fecf!ve Separation and Processing Integrated Program (ESP-
IP), DOE, EM-0126P, 1994.
81
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SOLVENT/CHEMICAL EXTRACTION
solidification/stabilization, incineration, or soil washing, depending on site-specific
conditions.
Emissions Control
Treated
Emissions
Recycled
Soil Contaminated
with Radioactive
Waste
>' >
>,
Solvent
with
Organic
Contaminants
r
Oversized
Rejects
Clean Soil Water
Radioactive
Liquid
Waste
Exhibit 2-19: Solvent Extraction
Target Contaminant Groups
Depending on the solvents used, solvent/chemical extraction may potentially
extract various radionuclides or mixed waste from contaminated media, using either a
batch or continuous flow system.92 Laboratory experiments with uranium mill tailings
indicate that inorganic salt extraction of radium and thorium is feasible, while mineral
acids have been used to extract radium, thorium, and uranium from mineral ores.
Complexing agents have also successfully removed radioisotopes of cobalt, iron,
chromium, uranium, and plutonium from nuclear process equipment. Laboratory
experiments suggest EDTA may be useful in extracting radium from soils and
tailings.93
Oak Ridge National Laboratory,Technology Evaluation Data Sheets, Part B, Dismantlement - Remedial Action, ORNL/M-
2751/V3/PI.B, September 1993.
93
U.S. Environmental Protection Agency, background Information Document for Radiation Site Cleanup Proposed Rule, Revised
Draft, August 1995.
82
-------
SOLVENT/CHEMICAL EXTRACTION
Solvent/chemical extraction effectively treated sediments, soils, and sludges
containing such organic contaminants as PCBs, VOCs, halogenated solvents, and
petroleum waste, as well as organically bound metals. This technology has also been
effective commercially in treating media containing heavy metals.
Technology Operating Characteristics
Exhibit 2-20 summarizes the operating characteristics of solvent/chemical
extraction.
Exhibit 2-20: Technical Characteristics of Solvent/Chemical Extraction
Characteristic Description
Destruction and Removal
Efficiencies (DREs)
Emissions: Gaseous and
Particulate
Costs: Capital and O&M
Results from 22 studies indicate that contaminant removal ranges from
13% to 100% for soils contaminated with radioactive waste and heavy
metals. These results vary significantly depending on the contaminant,
the solvent type used, and demonstration conditions. 94>95 Contaminant
removal is approximately 50% to 95% for petroleum and other
hydrocarbons. 96
Excavation may cause fugitive dust emissions. 97
Cost estimates range from $100 to $400 per ton. 98
Costs are lower if physical separation is used to remove "clean" soil
fractions prior to solvent extraction.
TJ.S. Environmental Protection Agency, Office of Research and DevelopmentTechnological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
U.S. Environmental Protection Agencyfmerging Technology Summary: Acid Extraction Treatment System for Treatment of
Metal Contaminated Soils, EPA/540/SR-94/513, August 1994.
Oak Ridge National Laboratory,Technology Evaluation Data Sheets, Part B, Dismantlement - Remedial Action, ORNL/M-
2751/V3/PI.B, September 1993.
U.S. Environmental Protection Agency and U.S. Department of DefenseRemediation Technology Screening Matrix and Reference
Guide/Version 1, 1993.
TJ.S. Department of Defense, Environmental Technology Transfer Committeeftemediation Technologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
83
-------
SOLVENT/CHEMICAL EXTRACTION
Exhibit 2-20: Technical Characteristics of Solvent/Chemical Extraction (Cont.)
Characteristic Description
Reliability
Process Time
Applicable Media
Pretreatment/Site
Requirements
Type and Quantity of
Residuals
Disposal Needs and
Options
A fully developed technology. Bench-scale, laboratory-scale, and pilot-
scale tests have been performed for soils contaminated with
radionuclides.99'100 Several pilot-scale and full-scale tests have been
completed for application to soils contaminated with petroleum
hydrocarbons, PCBs, and other organics. 10U°2 Pilot-scale and full-scale
tests on a commercial level have been performed for soils contaminated
with heavy metals.103'104
Throughput rate may range from 2 to 5 tons per hour. 105
Soil, sludges, and sediments
Soil excavation, soil characterization (i.e., particle size, partition
coefficient, action exchange capacity, organic content, moisture
content, and the presence of metals volatiles, clays, and complex
waste), and treatability studies are required. 106
Process liquid residue consisting of contaminant-rich solvent. 107
The process liquid residue concentrated with contaminants must
undergo further treatment, storage, or disposal. Soils that do not meet
cleanup requirements must be treated further, stored, or disposed of. 108
U.S. Environmental Protection Agency, Office of Research and Deve\opmentTechnological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
\J.S. Department of Energy, Office of Technology Developmentfiffective Separation and Processing Integrated Program (ESP-
IP), DOE, EM-0126P, 1994.
Oak Ridge National Laboratory,Technology Evaluation Data Sheets, Part B, Dismantlement - Remedial Action ORNL/M-
2751/V3/PI.B, September 1993.
U.S. Department of Defense, Environmental Technology Transfer Committeeftemediation Technologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
lmlbid, pg. 3-39.
TJ.S. Environmental Protection Agency Emerging Technology Summary: Acid Extraction Treatment System for Treatment of
Metal Contaminated Soils, EPA/540/SR-94/513, August 1994.
Oak Ridge National Laboratory,Technology Evaluation Data Sheets, Part B, Dismantlement - Remedial Action, ORNL/M-
2751/V3/PI.B, September 1993.
TJ.S. Department of Defense, Environmental Technology Transfer Committeeftemediation Technologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
I07lb,d.
loslb,d.
84
-------
SOLVENT/CHEMICAL EXTRACTION
Exhibit 2-20: Technical Characteristics of Solvent/Chemical Extraction (Cont.)
Characteristic Description
Post-treatment Conditions
Ability to Monitor
Effectiveness
The distilled vapor consisting of relatively pure solvent is recycled into
the extraction process. The process liquid residue may be treated
(preferably by ion exchange or precipitation), stored, or disposed of. If
sufficiently clean, the soil may be returned to the excavation site.
Otherwise it is treated further, stored, or disposed of. 109
Data not available
Site Considerations
Soil properties such as particle size, pH, partition coefficient, cation exchange
capacity, organic content, moisture content, and contaminant concentrations and
solubilities are factors that could affect the efficiency and the operability of
solvent/chemical extraction. Careful treatability studies are encouraged. Soils with
high clay, silt, or organic content may cause dewatering problems in the contaminated
waste stream; chemical extraction is not practical for soil with more than 6.7 percent
organic material (humus).110
Equipment and facilities are needed to perform the solvent/chemical extraction
process and to store waste residuals. Whether the soil can be returned to the site with
no further treatment will depend on cleanup requirements. Facility and process costs
vary significantly depending on the pretreatment, extraction, and post-treatment
required.
2.7.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
As an ex-situ technology, soil is removed and treated and returned as fill that
may contain some residuals from the chemical extraction process. Risks from external
Oak Ridge National Laboratory,Technology Evaluation Data Sheets, Part B, Dismantlement - Remedial Action ORNL/M-
2751/V3/PI.B, September 1993.
no
U.S. Environmental Protection Agenct, Background Information Document for Radiation Site Cleanup Proposed Rule, Revised
Draft, August 1995.
85
-------
SOLVENT/CHEMICAL EXTRACTION
exposure or long-term direct contact are thus reduced or eliminated. Liquid process
waste remains contaminated and must be treated further, stored, or disposed of.
Compliance with ARARs
Treatment must result in soil levels that comply with NRC and RCRA LDR
requirements. The requirements of RCRA LDRs may also apply to the residual waste
produced from this technology. Any aqueous discharges must comply with MCLs,
NPDES discharge limits, or total activity annual release limits. Compliance with other
ARARs must be determined on a site-specific basis.
Long-Term Effectiveness
Since contaminants are removed from soil, this technology is very effective in
the long-term. Treated media can only be returned to the site if they meet site-specific
requirements. Additional studies are necessary to document the effectiveness of
removing radioactive and mixed waste from the soil.
Reduction of Radiotoxicity. Mobility, or Volume
By removing contaminants, this technology reduces the overall toxicity of the
contaminated media. It also concentrates the contaminants into a smaller volume,
allowing more efficient final disposal. The process liquid residue containing
concentrated waste must be treated further, stored, or disposed of. The treated soil
may also require separate storage or disposal, depending on cleanup standards.
Short-Term Effectiveness
Excavation associated with solvent/chemical extraction poses a potential health
and safety risk to site workers due to fugitive dust emissions and direct contact with
contaminated soil. Personal protective equipment, at a level commensurate with the
contaminants involved, may be required during excavation. With enclosed systems
and use of dust control measures during soil preparation, this technology poses little
threat to the surrounding community.
Implementability
This technology may be used to remove radionuclides and mixed waste,
although this application requires further development. In addition to excavation, soil
pretreatment and post-treatment processing may be required. Field trials and careful
treatability studies are necessary to determine any limiting constraints.
86
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SOLVENT/CHEMICAL EXTRACTION
87
-------
SOLVENT/CHEMICAL EXTRACTION
Cost
Medium to high capital and operating and maintenance costs are associated
with this technology. Costs range from $100 to $400 per ton. Facility and process
costs vary depending on the pretreatment, extraction, and post-treatment required. A
multiple-stage extraction process would add to the capital and operating costs.
Operating and maintenance costs are also associated with storing of the treatment
process waste.
2.7.3 Summary
Solvent/chemical extraction has effectively treated media contaminated with
radionuclides. Its efficiency depends on many site-specific conditions, and further
development and site-specific characterization is needed to ensure effectiveness for all
types of radioactive materials.
Factors that may limit this technology's applicability and effectiveness include:
traces of solvents may remain in treated soils toxicity of the solvent is an
important consideration;
some soil types and moisture content levels will adversely impact process
performance;
multiple solvents may be needed for mixed waste and mixed radionuclides;
chemical extractants tend to dissolve a large portion of the soil matrix if
more than 2 to 3 percent of the matrix is dissolved, this technology may not
be feasible;
interference from thorium may limit the application of EDTA in removing
radium when both radionuclides are present.111
Exhibit 2-21 summarizes the data and analyses presented in this profile and can
be used for technology comparison.
in
Ibid.
88
-------
SOLVENT/CHEMICAL EXTRACTION
Exhibit 2-21: NCP Criteria for Solvent/Chemical Extraction
NCP Criterion
Evaluation
Performance Data
Overall Protectiveness
As an ex-situ treatment
technology, reduces risk due
to long-term exposure.
Excavation process poses a
potential risk to site workers.
Fully demonstrated for non-
radioactive waste.
Further studies are needed to
determine effectiveness in treating
radioactive and mixed waste.
Compliance with ARARs
The requirements of RCRA
LDRs , CWA, and NRC may
apply to the effluent and
residual waste produced
from this technology.
Performance data must be assessed
in relation to preremediation
concentrations and cleanup
standards to determine compliance
with ARARs.
Reduction of Radiotoxicity,
Mobility, or Volume
Removes radionuclides; does
not affect toxicity, mobility,
or volume.
Process removes most types of
radionuclides from contaminated
media to varying degrees.
Process liquid residuals contain
concentrated contaminants.
Long-Term Effectiveness and
Performance
Removes contaminants from
soils, permanently
addressing principal threats.
Process liquid residuals
contain concentrated
contaminants.
Needs further development to ensure
effectiveness in treating radioactive
waste.
Short-Term Effectiveness
Potential health and safely
risk to workers from
excavation.
Requires personal protective
equipment during excavation at a
level commensurate with the
contaminants involved.
With enclosed systems and dust
control measures during soil
preparation, appears to pose little
threat to the community.
Implementability
Applies to soils, sediments,
and sludges.
Disposal or storage facilities
need to be available for
process liquid residuals.
Processing pretreatment and post-
treatment of the soil may be
required.
Treatability studies and field trials
are necessary to identify the
technology's limitations.
Cost
Medium to high capital and
O&M costs due to off-site
storage or disposal of
residuals.
$100 to $400 per ton.
89
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90
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PHYSICAL SEPARATION
PHYSICAL SEPARATION
TECHNOLOGIES
Physical separation technologies are a class of treatment in which radionuclide-
contaminated media are separated into clean and contaminated fractions by taking advantage
of the contaminants' physical properties. These technologies work on the principle that
radionuclides are associated with particular fractions of the media, which can be separated
based on their size and other physical attributes. In solid media (i.e. soil, sediment) most
radioactive contaminants are associated with smaller particles, known as soil fines (clays and
silts). Radionuclides in liquid media are either solvated by the liquid media (i.e., one
molecule of the radionuclide surrounded by many molecules of the liquid) or are present as
microscopic particles suspended in the solution. Physical separation of the contaminated
media into clean and contaminated fractions reduces the volume of contaminated media
requiring further treatment and/or disposal.
Physical separation technologies can be applied to a variety of solid and liquid media
including soil, sediment, sludge, groundwater, surface water, and debris. In addition to
treating radionuclides, physical separation technologies can be used to treat semivolatile
organic compounds, oils, PCBs, and heavy metals.
The profiles in this Section address the following physical separation technologies:
dry soil separation, soil washing, and column and centrifugal flotation.
91
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DRY SOIL SEPARA TION
2.8 DRY SOIL SEPARATION
J
2.8.1 Technology Characteristics
Description
Dry soil separation separates radioactive particles from clean soil particles. In
this process, radionuclide-contaminated soil is excavated and screened to remove large
rocks. Large rocks are crushed and placed with soil on a conveyor belt, which carries
the soil under radiation detectors that measure and record the level of radiation in the
material. Radioactive particles are tracked and mechanically diverted through
automated gates, which separate the soil into contaminated and clean segments.
Volumes of radioactive materials can be further processed and/or disposed of (see
Exhibit 2-22).112 Dry soil separation can substantially reduce the volume of
radioactive waste (>90%) and has been used on a commercial scale at Johnston Atoll
in the South Pacific and the Savannah River site in South Carolina.113
Automated
Gates
Further Treatment
and/or Disposal
Exhibit 2-22: Dry Soil Separation
U.S. Environmental Protection Agency'Approaches for the Remediation of Federal Facility Sites Contaminated with Explosive
or Radioactive Waste, EPA/625/R-93/013, September 1993.
113
Thermo Nutech, Environmental Field Services Group Statement of Qualifications and Description of Thermo Nutech 's
Segmented Gate System, Oakridge, TN, 1996.
93
-------
DRY SOIL SEPARA TION
Target Contaminant Groups
Dry soil separation has been used to sort radioactive particles from
contaminated soils at Johnston Atoll and the Savannah River site. This technique
effectively treats soils contaminated with gamma emitting radionuclides, including Th,
U, Cs-137, Co-60, Pu-239, Am-241 and Ra-222. Dry soil separation can effectively
treat large volumes of contaminated soil and can treat radioactively contaminated
asphalt, concrete, or any solid host matrix transportable by conveyor belts.114
Technology Operating Characteristics
Exhibit 2-23 summarizes the operating characteristics of dry soil separation.
Exhibit 2-23: Technical Characteristics of Dry Soil Separation
Characteristic Description
Destruction and Removal
Efficiencies (DREs)
Emissions: Gaseous and
Particulate
Volumes of soils contaminated with Pu-239 and Am-241 on Johnston
Atoll were reduced by >90%. Am-241 and Ra-222 concentrations in
clean soil fractions were reduced below their respective limits of
detection at 2pCi/g and 5pCi/g.115'116
A 99% volume reduction of radioactively contaminated material was
demonstrated at the Savannah River Site. Cs-137 levels in clean soil
fractions were reduced by 99% to less than the level of detection at
4pCi/g.117'118
Excavation and processing may cause fugitive gas and dust
emissions.
U.S. Environmental Protection Agency,SuperfundInnovative Technology Evaluation Program, Technology Profiles Seventh
Edition, EPA/540/R-94/526, November 1994.
117
Thermo Nutech, Environmental Field Services Group Statement of Qualifications and Description of Thermo Nutech 's
Segmented Gate System, Oakridge, TN, 1996.
us
U.S. Environmental Protection Agency,Superfund Innovative Technology Evaluation Program, Technology Profiles Seventh
Edition, EPA/540/R-94/526, November 1994.
94
-------
DRY SOIL SEPARA TION
Exhibit 2-23: Technical Characteristics of Dry Soil Separation (Cont.)
Characteristic Description
Costs: Capital and O&M
Reliability
Process Time
Applicable Media
Pretreatment/Site Requirements
Type and Quantity of Residuals
Disposal Needs and Options
Post-Treatment Conditions
The total cost to treat over 100,000 cubic yards of radioactively
contaminated soil on Johnston Atoll was $15 million. Capital costs
of $2.4 million were needed to construct the treatment facility. 119
The system consistently and successfully segregates contaminated
soil into radioactive and clean segments. Dry soil separation
accounts for every kilogram of excavated soil and produces a very
clean soil fraction, which can be safely returned to the site or
potentially sold as a commodity, due to its uniform size. 12°
The entire cleanup process (excavating and processing over 100,000
cubic yards of radionuclide-contaminated soil) on Johnston Atoll is
expected to take 140 weeks. 121 Tons/hour information not available.
Soil, sand, dry sludge, crushed asphalt or concrete, or any dry host
matrix that can be transported by conveyor belts. m
Soil excavation is required. Large rocks, concrete, or asphalt must be
crushed before being placed on the conveyor belt. Soil must be
contaminated with gamma emitting radionuclides.
Large quantities of clean soils can be returned to the site or sold for
fill. Small quantities of radioactive materials require further
treatment and/or disposal.
Large volumes of clean soil can be returned to the site or sold as
clean fill.
Radioactively contaminated materials may require further treatment
and/or disposal. Contaminated materials may be classified as high
level or TRU waste, depending on the types of waste present, and
could therefore require special handling and disposal.
Clean soil fractions can be returned to the site. Radionuclide-
contaminated segments require further treatment and/or disposal.
U.S. Environmental Protection Agency Approaches for the Remediation of Federal Facility Sites Contaminated with Explosive
or Radioactive Waste, EPA/625/R-93/013, September 1993.
U.S. Environmental Protection AgencyJSuperfund Innovative Technology Evaluation Program, Technology Profiles Seventh
Edition, EPA/540/R-94/526, November 1994.
95
-------
DRY SOIL SEPARA TION
Exhibit 2-23: Technical Characteristics of Dry Soil Separation (Cont.)
Characteristic
Description
Ability to Monitor Effectiveness
Because all excavated soil is screened for radioactivity, non-
radioactive materials can be returned to the site with no further
monitoring.123 Radioactive components require proper treatment
and/or disposal and monitoring.
Site Considerations
Dry soil separation can be used when gamma emitting radionuclides are present
at a site and radioactivity is distributed in a nonuniform fashion. It can treat any dry
material that can be crushed to a uniform size, and can be used at any site where
contaminated materials can be removed or excavated. A commercially available
portable treatment system could be moved to a wide variety of sites.124
2.8.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
Dry soil separation can substantially reduce the volume of radionuclide-
contaminated materials at a site. However, radionuclide-contaminated materials may
require special handling, or treatment and/or disposal. Fugitive gas and dust emissions
during excavation and processing could pose risks to site workers and local
communities.
Compliance with ARARs
The treatment must result in residual soil levels that comply with NRC, RCRA,
and any applicable local regulatory requirements. Particulate emissions would be
regulated by the Clean Air Act. Contaminated fractions would have to be treated
and/or disposed of according to NRC and/or DOE orders.
Long-Term Effectiveness
U.S. Environmental Protection Agency, Approaches for the Remediation of Federal Facility Sites Contaminated with Explosive or
Radioactive Waste, EPA/625/R-93/013, September 1993.
124
Thermo Nutech, Environmental Field Services Group Statement of Qualifications and Description of Thermo Nutech 's
Segmented Gate System, Oakridge, TN, 1996.
96
-------
DRY SOIL SEPARA TION
Because all excavated soils are screened and segregated by their radioactivity,
clean soils can be returned to the site or commercially sold, in some cases.125 Volume
reductions of radionuclide-contaminated soils >90 percent ensure that most of the soil
can be safely reused.126 However, highly radioactive residual materials require further
treatment and/or disposal.
Reduction of Radiotoxicity. Mobility, or Volume
This technology effectively separates radioactive soil particles from clean soil
particles, thus reducing the volume of soil requiring further treatment or disposal.
Large percentages of the soil can be safely reused. However, excavation and
processing increase fugitive gas and dust emissions of radionuclide contaminants;
remaining radioactive materials require further treatment and/or disposal. Therefore,
while dry soil separation reduces the volume of the contaminated soil, the toxicity and
mobility of the original contaminants are not addressed by this technology.
Short-Term Effectiveness
This process works best for soils contaminated with gamma emitting
radionuclides, and may not adequately separate radioactive materials that are weak
gamma emitters. Additionally, fugitive gas and dust generated during excavation and
processing may pose health and safety risks for workers and the local community.
Implementability
The technology can be implemented without significant difficulties, however
the soil must first be excavated. Contaminated soil residuals require further treatment
and/or disposal. Portable treatment plants are commercially available.
125
U.S. Environmental Protection Agency Approaches for the Remediation of Federal Facility Sites Contaminated with Explosive
or Radioactive Waste, EPA/625/R-93/013, September 1993.
126
Thermo Nutech, Environmental Field Services Group Statement of Qualifications and Description of Thermo Nutech 's
Segmented Gate System, Oakridge, TN, 1996.
97
-------
DRY SOIL SEPARA TION
Cost
Costs of using this technology can be attributed to leasing capital equipment;
operating large capacity systems, or operating the systems for long periods of time;
excavation; and disposal of residual radioactive waste.
2.8.3 Summary
Dry soil separation has been applied to radionuclide-contaminated soils at
Johnston Atoll and the Savannah River site in South Carolina. In both cases, this
technology has proven very effective at substantially reducing the volumes of
radionuclide contaminated soils achieving reductions of >90 percent at each site.127
Further, dry soil separation is economical because it allows large volumes of clean
material to be returned to a site without further processing or monitoring.128 This
technology works best, however, with gamma emitting radionuclides. Radioactive
fractions require additional treatment and/or disposal. Fugitive gas and dust emissions
also need to be controlled to minimize health risks to workers and local communities.
The following factors may limit the applicability and effectiveness of this process:
ability to excavate or remove contaminated materials;
ability to control fugitive gas and dust emissions during excavation and
processing;
radionuclide types and distribution in the soil;
ability to crush dry substrates;
additional management of residuals.
Exhibit 2-24 summarizes the data and analyses presented in this profile and can
be used for technology comparison.
127
Ibid.
98
-------
DRY SOIL SEPARA TION
Exhibit 2-24: NCP Criteria for Dry Soil Separation
NCP Criterion
Evaluation
Performance Data
Overall Protectiveness
Substantial volume reductions
of radioactive material
possible.
Radioactive residuals need
additional treatment and/or
disposal.
Fugitive gas and dust
emissions could pose health
risks to workers and local
communities.
Volumes of soils contaminated with
Pu-239 and Am-241 on Johnston Atoll
were reduced by >90%. Am-241 and
Ra-222 concentrations were reduced
below their respective limits of |
detection at 2pCi/g and 5pCi/g.
A 99% volume reduction of
radioactively contaminated material
was demonstrated at the Savannah
River site. Cs-137 levels were
reduced by 99% to less than the level
of detection at 4pCi/g.131'132
Compliance with ARARs
The requirements of RCRA
LDR, CAA, NRC, and DOE
orders may apply to the
residual waste produced from
this technology.
Performance data, such as removal
efficiencies, must be assessed in
relation to preremediation
concentrations and cleanup standards
to determine compliance with
ARARs.
Long-Term Effectiveness
and Permanence
Reduces the volume of
radioactively contaminated
soils.
Waste produced in this process
requires further treatment
and/or disposal.
Technology achieves consistent and
successful segregation of
contaminants from soil, resulting in
significant volume reduction of
contaminated soils.
Waste produced in this process
requires further treatment and/or
disposal.
Reduction of
Radiotoxicity, Mobility,
or Volume
Does not reduce toxicity or
mobility of contaminants in
separated waste.
Reduces the volume of
radioactively contaminated
soils.
Process separates clean and
contaminated soil fractions, thereby
reducing the volume of soil and
addressing principal threats.
Contaminated materials will require
further treatment and/or disposal.
Ibid.
Thermo N utech, Environmental Field Services Group, Statement of Qualifications and Description of Thermo Nutech's
Segmented Gate System, Oakridge, TN, 1996.
99
-------
DRY SOIL SEPARA TION
Exhibit 2-24: NCP Criteria for Dry Soil Separation (Cont.)
NCP Criterion
Evaluation
Performance Data
Short-Term Effectiveness
Fugitive gas and dust
emissions could pose health
threats to workers and local
communities.
Fugitive gas and dust emissions could
pose health threats to workers and
local communities.
Implementability
This technology is
commercially available and
has successfully treated
radionuclide-contaminated
soils.
Requires soil excavation.
A mobile commercial treatment
system is available.
Cost
Varying costs are associated
with this technology,
depending on site-specific
conditions and requirements.
Costs for treating and/or
disposing of separated
radioactive waste could be
high.
Costs of this treatment are
considered low compared to
some alternatives.
Treatment costs at Johnston Atoll
were $2.4 million to build the plant
and a total of $ 15 million to clean the
entire site (at least 100,000 cubic
yards of contaminated soil were
treated).133
100
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SOIL WASHING
2.9 SOIL WASHING
J
2.9.1 Technology Characteristics
Description
Soil washing is a process in which water, with or without surfactants, mixes with
contaminated soil and debris to produce a slurry feed. This feed enters through a scrubbing
machine to remove contaminated fine soil particles (silts and clay) from granular soil
particles. Contaminants are generally bound more tightly to the fine soil particles and not to
larger grained sand and gravel. Separation processes include screening to divide soils into
different particle sizes, and chemical extraction of radionuclides. The output streams of
these processes consist of clean granular soil particles, contaminated soil fines, and
process/wash water, all of which are tested for contamination. Soil washing is effective
only if the process transfers the radionuclides to the wash fluids or concentrates them in a
fraction of the original soil volume. In either case, soil washing must be used with other
treatment technologies, such as filtration or ion exchange. Clean soil (sand and gravel) can
be returned to the excavation area, while remaining contaminated soil fines and process
waste are further treated and/or disposed of.
Soil washing is most effective when the contaminated soil consists of less than 25 percent
silt and clay and at least 50 percent sand and gravel; soil particles should be between 0.25
mm and 2 mm in diameter for optimum performance. When soil particles are too large
(greater than 2 mm in diameter), removal of oversized particles may be required; when
particles are smaller than 0.063 mm in diameter soil washing performance is poor because
these particles are very difficult to separate into contaminated and uncontaminated
components.
Other factors impacting the effectiveness of soil washing include the cation exchange
capacity of the soil and the use of extractants. If the soil's cation exchange capacity is too
high, separating pollutants from the soil particles is difficult. Alternatively, heating the
wash water and using surfactants may make metal removal more efficient.134
One type of soil washing system developed specifically by EPA for treating radioactively
contaminated soils is the VOlume Reduction/Chemical Extraction (VORCE) plant.
VORCE pilot plants have been tested at Department of Energy sites in New Jersey and
TJ.S. Environmental Protection Agency .Innovative Site Remediation Technology, Soil Washing/Soil Flushing Volume 3, EPA
542-B-93-012, November 1993.
101
-------
SOIL WASHING
Tennessee. Initial studies have shown that systems similar to VORCE plants effectively
reduce the mass of radioactively contaminated soils. EPA believes the pilot operations
could be expanded to treat larger quantities of soil and to become more cost-effective.135
Exhibit 2-25 illustrates the general process involved with soil washing.
Volatiles
Volatiles
Soil Contaminated
with Radioactive
Waste
Soil
Homogenizing/
Screening
Prepared
Soil
Clean
Oversized
Particles
Soil Washing
Process
1 Washing
Rinsing
Size Separation
Gravity Separation
Attrition Scrubbing
Clean
Soil
Contami nate d
Sludges/ Fines
Exhibit 2-25: Soil Washing
Target Contaminant Groups
Soil washing has been used in two pilot plant tests, to decontaminate plutonium-
contaminated soil at a site in Rocky Flats Colorado and to extract radium from uranium mill
tailings at a site in Canada.136 The VORCE plant has been used at sites in Tennessee and
New Jersey to treat thorium- and cesium-contaminated soils.137 Soil washing has also been
U.S. Department of Energy Results of a Soil Washing Demonstration Project for Low-Level Radioactively Contaminated Soi}
DOE/OR/21949-404, June 1996.
U.S. Environmental Protection Agency Technological Approaches to the Cleanup of Radiologically Contaminated Superfund
Sites, EPA/540/2-88/002, August 1988.
137
U.S. Department of Energy ,Results of a Soil Washing Demonstration Project for Low-Level Radioactively Contaminated Soil,
DOE/OR/21949-404, June 1996.
102
-------
SOIL WASHING
used to treat other radionuclides, including uranium, thorium, and cesium; organics,
including polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs),
pentachlorophenol (penta), creosote, heavy petroleum, cyanides; and heavy metals,
including cadmium, chromium, copper, lead, mercury, nickel, and zinc.
Technology Operating Characteristics
Exhibit 2-26 summarizes the operating characteristics of dry soil washing.
Exhibit 2-26: Technical Characteristics of Soil Washing
Characteristic Description
Destruction and Removal
Efficiencies (DREs)
Emissions: Gaseous and
Particulate
In pilot-plant test runs, plutonium-contaminated soils to 45, 284, 7515,
1305, and 675 pCi/g were cleaned to contamination levels of 1, 12, 86,
340, and 89 pCi/g respectively, using different processes. 13S
At a site in Texas, soil washing combined with ion exchange reduced
uranium concentrations from an average of 70 ppm to 20.7 ppm. This
process cleaned the soil sufficiently well that virtually all the soil could
be returned to the site. 139
In an experiment with Pu-contaminated soil, contaminated soil mass was
reduced by 65% and soil exhibiting activity levels in the range of 900 to
140,000 pCi/g of Pu was reduced to <6 pCi/g Pu. 14°
Treating soils at sites in New Jersey and Tennessee with the VORCE
plant reduced the mass of contaminated soils by 63.8% and 70%
respectively. The VORCE plant reduced Th-232 concentrations from
18. 1 pCi/g to <5 pCi/g at the New Jersey site, and reduced Cs-137 levels
from 160 pCi/g to <50 pCi/g at the Tennessee site. 141
Some gaseous emissions may result if VOCs are in waste.
Excavation may lead to fugitive gas and dust emissions.
TJ.S. Environmental Protection Agency Technological Approaches to the Cleanup ofRadiologically Contaminated Superfund
Sites, EPA/540/2-88/002, August 1988.
U.S. Environmental Protection Agency, Federal Remediation Technologies Roundtable§y«o/Me,s of Federal Demonstrations of
Innovative Site Remediation Technologies, EPA, 542/B-92/003, August 1992.
140
Argonne National Laboratory,,^;/ Washing as a Potential Remediation Technology for Contaminated DOE Sites,DE93-
009205, March 1993.
141
U.S. Department of Energy ,Results of a Soil Washing Demonstration Project for Low-Level Radioactively Contaminated Soil,
DOE/OR/21949-404, June 1996.
103
-------
SOIL WASHING
Exhibit 2-26: Technical Characteristics of Soil Washing (Cont.)
Characteristic Description
Costs: Capital and O&M
Reliability
Process Time
Applicable Media
Pretreatment/Site
Requirements
Type and Quantity of
Residuals
Disposal and transportation costs for radioactive soils are about $900 per
ton. Based on pilot testing results, volume reduction at a rate of 1 .5 tones
per hour costs approximately $300 per hour. 142
Treatment costs for the VORCE plant ranged from $111 to $134 per ton for
processing between 20 to 100 tons per hour. Total costs could be as high as
$280 per ton when waste is transported off site. 143
The process consistently and successfully segregates contaminated soil into
two unique streams: washed soil and fines slurry. The washed soil was
safely returned to the site with no further treatment. 144
A soil washing plant in Bruni, Texas, achieved a cleanup rate of 20 tons of
radionuclide-contaminated soil per hour. 145
An expanded VORCE type plant could process 20 to 100 tons of
radionuclide contaminated soil per hour. U6
Soil, sediment, sludge
Soil excavation is required, as is mechanical screening, to remove various
oversized materials and separation to generate coarse- and fine-grained
fractions. Site soils should have the proper grain size distribution, clay
content, and cation exchange capacity. Radionuclides at the site largely
determine the proper soil washing mixture or feasibility of the process.
Process wash waters, silt, and clay. Contaminated silt, clay, and wash
waters may require further treatment or disposal.
U.S. Environmental Protection Agency, Federal Remediation Technologies Ro\mdtab\e§ynopses of Federal Demonstrations of
Innovative Site Remediation Technologies, EPA, 542/B-92/003, August 1992.
143
U.S. Department of Energy ,Results of a Soil Washing Demonstration Project for Low-Level Radioactively Contaminated Soil
DOE/OR/2 1949-404, June 1996.
TJ.S. Environmental Protection Agency innovative Site Remediation Technology, Soil Washing/Soil Flushing Volume 3, EPA
542-B-93-012, November 1993.
U.S. Department of Energy, Results of a Soil Washing Demonstration Project for Low-Level Radioactively Contaminated Soi}
DOE/OR/2 1949-404, June 1996.
104
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SOIL WASHING
Exhibit 2-26: Technical Characteristics of Soil Washing (Cont.)
Characteristic Description
Disposal Needs and Options
Post-Treatment Conditions
Ability to Monitor
Effectiveness
Process water is potentially suitable for recycling as wash water, but would
likely require further treatment (e.g., ion-exchange) before being recycled.
If treated water cannot be reused as wash water it must be discarded in
accordance with applicable discharge requirements. 147
Contaminated silt, clay, and wash waters may require further treatment or
disposal. Contaminated soil fines could be incinerated or disposed of as
radioactive waste; wash water can be treated by ion exchange. 148
Process wash water may become radioactively contaminated. Treating this
water through ion exchange will allow water to be reused in some cases. 149
Contaminated silt, clay, and wash waters may require further treatment or
disposal.
Partitioned soil and wash water must be tested for radioactive
contamination; monitoring is not difficult.
Site Considerations
Soil washing is useful in situations where radioactive contaminants are closely
associated with fine soil particles and soils have the proper particle size distribution.
Better success can be obtained with sandy soils and soils with low cation exchange
capacities; humus soils (i.e. soils with high, naturally occurring, organic content or high
cation exchange capacities) may be difficult to clean.150
Whether the segregated uncontaminated washed soil can be returned to the site with no
further treatment, thus increasing cost-effectiveness, depends on cleanup and land disposal
requirements. Soil character, moisture content, particle size distribution, and contaminant
concentrations and solubilities are factors that impact the efficiency and operation of soil
washing.151
U.S. Environmental Protection Agency,Technological Approaches to the Cleanup of Radiologically Contaminated Superfund
Sites, EPA/540/2-88/002, August 1988.
TJ.S. Environmental Protection AgencyJnnovative Site Remediation Technology, Soil Washing/Soil Flushing Volume 3, EPA
542-B-93-012, November 1993.
U.S. Environmental Protection Agency,Technological Approaches to the Cleanup of Radiologically Contaminated Superfund
Sites, EPA/540/2-88/002, August 1988.
I50lb,d.
U.S. Environmental Protection Agency Jnnovative Site Remediation Technology, Soil Washing/Soil Flushing Volume 3, EPA
542-B-93-012, November 1993.
105
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SOIL WASHING
2.9.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
Although this technology is not yet fully demonstrated, protectiveness has been achieved
in preliminary studies. In some cases the volume of radionuclide-contaminated soil was
reduced 30 to almost 100 percent.152 However, soil fines generally remain contaminated
and require further treatment and/or disposal; process wash water may also be
contaminated and may require further treatment and/or disposal.
Compliance with ARARs
The treatment must result in residual soil levels that comply with NRC, RCRA, and any
applicable local regulatory requirements.
Long-Term Effectiveness
Although studies indicate that contaminants are consistently and successfully segregated
from soil, more studies are needed to document the effectiveness of segregating
radioactive materials from soil.
Reduction of Radiotoxicity. Mobility, or Volume
This technology effectively separates contaminated soil fines from clean, larger soil
particles, thereby reducing the volume of soil requiring further treatment or disposal.
However, the process wash water may contain elevated levels of radionuclide
contaminants and may also require treatment and/or disposal. While soil washing reduces
the volume of the contaminated soil, it does not reduce the toxicity or mobility of the
original contaminants, and, therefore, additional management of residuals is required.
Short-Term Effectiveness
Fugitive gas and dust generated during excavation may lead to health and safety risks
for workers.
152
Ibid.
106
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SOIL WASHING
Implementability
This process may not work for humus soil, nor for other than low levels of radionuclide
contamination in soils. Process wash water must be stripped of radioactive
contaminants.153 Demonstrations indicate the technology can be implemented without
significant difficulties. However, the soil must first be excavated, residual soil fines
require further treatment and/or disposal, and the process wash water may also require
treatment and/or disposal. If onsite plants are not constructed, transportation costs could
increase the treatment costs significantly.
Cost
Costs of using this technology are attributed to leasing capital equipment; operating
large capacity systems, or operating the systems for long periods of time; transportation;
and disposal of residual radioactive waste.
2.9.3 Summary
Soil washing has been applied to organic- and heavy metal-contaminated soil, and has
been pilot tested with radionuclide-contaminated soil. While this technology is generally
effective in treating these contaminants in soil, further development is needed to ensure
effectiveness with radionuclide contamination in soil. Soil washing appears to work best
for soils contaminated with low-level radioactivity. The following factors may limit the
applicability and effectiveness of this process: organic content of soil or high soil cation
exchange capacities; additional management of residuals; radionuclide concentrations and
types in the soil; and soil particle size.
Soil washing costs may be reduced by leasing equipment and processing the soils in
large quantities or over long periods of time.
Exhibit 2-27 summarizes the data and analyses presented in this profile and can be used
for technology comparison.
U.S. Environmental Protection Agency,Technological Approaches to the Cleanup ofRadiologically Contaminated Superfund
Sites, EPA/540/2-88/002, August 1988.
107
-------
SOIL WASHING
Exhibit 2-27: NCP Criteria for Soil Washing
NCP Criterion
Evaluation
Performance Data
Overall Protectiveness
Preliminary studies
indicate that
protectiveness is
achieved.
The VORCE plant reduced the
mass of contaminated soils by
63.8 % to 70% and reduced Th-
232 concentrations from 18.1
pCi/g to <5 pCi/g and Cs-137
levels from 160 pCi/g to <50
pCi/g.154
Compliance with
ARARs
RCRA LDR, CWA,
and NRC requirements
may apply to the
effluent and residual
waste produced from
this technology.
Performance data, such as
removal efficiencies, must be
assessed in relation to
preremediation concentrations
and cleanup standards to
determine compliance with
ARARs.
Long-Term
Effectiveness and
Permanence
This technology needs
further development to
ensure effectiveness
with radioactive
materials.
Residual waste is
present in soil fines and
may be present in
process/wash waters.
Demonstrations and studies
indicate a consistent and
successful segregation of
contaminants from soil.
Residual contamination is present
in soil fines and may be present
in process/wash waters.
Reduction of
Radiotoxicity, Mobility,
or Volume
Does not reduce
toxicity or mobility of
contaminants in
residuals.
Process separates clean (granular
soil and gravel) and contaminated
(clay and silt) soil fractions,
thereby reducing the volume of
soil and addressing principal
threats.
Process/wash waters may be
contaminated and may require
further treatment or disposal.
Short-Term
Effectiveness
Technology does not
pose an immediate
threat.
Potential risk to workers or
nearby community due to
excavation and processing.
U.S. Department of Energy ,Results of a Soil Washing Demonstration Project for Low-Level Radioactively Contaminated Soil,
DOE/OR/21949-404, June 1996.
108
-------
SOIL WASHING
Exhibit 2-27: NCP Criteria for Soil Washing (Cont.)
NCP Criterion
Evaluation
Performance Data
Implementability
Variations of this
technology are widely
available and have been
used successfully to
treat radionuclide-
contaminated soils.
Requires excavation and an
adequate water supply.
Numerous commercial soil
washing systems are available.
Cost
Costs of this technology
vary depending on site-
specific conditions and
requirements.
Costs can be reduced by leasing
capital equipment.
Costs are reduced with larger
systems and systems that operate
on-line for extended periods of
time
109
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FLOTATION
2.10 FLOTATION
J
2.10.1 Technology Characterization
Description
Flotation separates radionuclide-contaminated soil fractions (usually the fine
soil particles such as silts and clays) from the clean soil fractions (large granular soil
particles and gravel) in order to reduce the volume of soil requiring treatment or
disposal. During flotation, radionuclide-contaminated soil is pretreated to remove
coarse material and then mixed with water to form a slurry. A flotation agent (a
chemical that binds to the surface of the contaminated soil particles to form a water
repellent surface) is then added to the solution to make contaminated soil particles
float. Small air bubbles are then formed in the solution through either air injection or
chemical processes. These air bubbles adhere to the floating particles, transport them
to the surface, and produce a foam containing the radionuclide-contaminated soil
particles. The foam is mechanically skimmed from the surface or allowed to overflow
into another vessel, where it is collected for treatment and/or disposal. After
dewatering and drying and if the soil meets ARARs, the clean soil can then be returned
to the excavation area. Flotation can be performed in a stationary column or rotating
vessel, using centrifugal force to enhance the process (see Exhibit 2-28).
Exhibit 2-28: Flotation
Recycled Water
Air
/Flotation \ v Jr
V Agents t
V S TL Mjxcr > Flotation
Soil Fine
Soil Contaminated , r
Waste Post-Treatment
and/or Disposal of _
Contaminated Soil
k Soil/Water
Separation
J
(Cl
\M<
* w
[
ean (
sdia \
. /
aste
111
-------
FLOTATION
Target Contaminant Groups
Contaminants that can be treated using flotation include heavy metals, such as
lead and mercury, and radionuclides, such as uranium and plutonium. Flotation is
used extensively in the mining industry to concentrate constituents such as uranium
from ores. It has also been tested, with various mechanical designs for effectiveness in
reducing the volume of soil contaminated with plutonium, uranium, or heavy metals.
Technology Operating Characteristics
Exhibit 2-29 summarizes the operating characteristics of flotation.
Exhibit 2-29: Technical Characteristics of Flotation
Characteristic
Description
Destruction and Removal
Efficiencies (DREs)
In tests conducted by the U.S. Bureau of Mines, flotation was
95% effective in separating uranium from sandstone ores
containing 0.25% uranium oxide.155 Radium was reduced in
uranium mill tailings from 290-230 pCi/g to 50-60 pCi/g by
flotation.156 In bench scale tests with bismuth as a surrogate for
plutonium oxide, the separation effectiveness ranged from 70 to
90%.157
Emissions: Gaseous and
Particulate
If VOCs or radon are present in soil, gaseous emissions may be
generated during treatment. In addition, excavation of
contaminated soil may generate fugitive gas and dust.
Costs: Capital and O&M
Capital costs for a flotation unit vary from $25,000 to $160,000,
depending on the size of the unit. O&M costs vary from $3 to
$15 per 1,000 gallons of treated slurry. The larger the unit, the
lower the O&M cost per 1,000 gallons. However, capital costs
are lower for the smaller flotation units.158
Organization for Economic Cooperation and Deve\opment,Uranium Extraction Technology, OECD, Paris 1983.
156
Raicevic, D., Decontamination of Elliot Lake Uranium Tailing CIM Bulletin, 1970.
U.S. Department of Energy,Heavy Metals Contaminated Soil Project, Resource Recovery Project, andDynamic Underground
Stripping Project: Technology Summary, DOE/EM-0129P, February 1994.
\J.S. Environmental Protection Agency,Technological Approaches to the Cleanup ofRadiologically Contaminated Superfund
Sites, EPA/540/2-88/002, August 1988.
112
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FLOTATION
Exhibit 2-29: Technical Characteristics of Flotation (Cont.)
Characteristic Description
Reliability
Process Time
Applicable Media
Pretreatment/Site
Requirements
Type and Quantity of
Residuals
Disposal Needs and Options
Post-Treatment Conditions
Ability to Monitor
Effectiveness
Bench scale tests have shown consistent and successful
segregation of radionuclide-contaminated fines from clean,
larger, soil-particle fractions. 159 Clean soil may be returned to
the excavated site, although the fines and wash solution may
require further treatment and/or disposal.
Not documented in the literature reviewed.
Soil, sediment
Soil excavation; potential grinding of soil to reduce particle size
for treatment. 16°
Foam containing contaminated soil fines.
Excavated soil requires backfilling. Returned cleaned material
may contain some residual contamination. Radionuclide-
contaminated foam requires further treatment and/or disposal.
Residual foam containing radionuclide-contaminated soil fines
requires further treatment and/or disposal.
Clean soil fractions can easily be sampled and analyzed for
radionuclide contamination levels.
Site Considerations
Soil-specific site considerations, such as particle size and distribution,
radionuclide distribution, soil characteristics (clay, sand, humus, silt), specific gravity
and chemical composition, and mineralogical composition, may impact the
effectiveness of flotation. Larger soil particles may have to be ground or removed
from the soil prior to flotation. In addition, soils with high organic content (i.e., humus
soils) may be difficult to treat with this technology. Flotation is most effective at
separating soil particles in the size range of 0.1 - 0.01 mm. The availability of
appropriate flotation agents to bind to the contaminant(s) of concern is also important
to consider. If a flotation agent is not available for a particular contaminant, unless
one is developed the flotation process will be ineffective.161 To effectively remove
radionuclide-contaminated soil particles the solution used in the flotation process must
U.S. Department of Energy,Heavy Metals Contaminated Soil Project, Resource Recovery Project, andDynamic Underground
Stripping Project: Technology Summary, DOE/EM-0129P, February 1994.
\J.S. Environmental Protection Agency,Technological Approaches to the Cleanup ofRadiologically Contaminated Superfund
Sites, EPA/540/2-88/002, August 1988.
I6llb,d.
113
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FLOTATION
be treated. For example, treatment of uranium mine tailings in Canada failed to
remove significant levels of radium from the tailings because high levels of dissolved
radium had built up in the recycled wash water, reducing the removal efficiency of the
process.162
2.10.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
This technology has not been fully demonstrated for reducing the volume of
radionuclide-contaminated soil. However, in tests conducted by the U.S. Bureau of
Mines flotation removed 95 percent of the uranium from sandstone ores containing
0.25 percent uranium oxide. Additional studies with uranium mill tailings showed
effective removal of radium.163 Given the demonstrated efficiency of this technology,
it is expected to effectively reduce the volume of contaminated soil, thus reducing the
potential threat to human health.
Compliance with ARARs
The treatment must result in residual soil levels that comply with NRC, RCRA,
and any local regulatory requirements.
Long-Term Effectiveness
Although mining industry operations have consistently and successfully
segregated contaminated fines from clean soil (i.e., uranium removal from sandstone
ore), additional studies are needed to document the effectiveness of separating
radionuclide-contaminated fines from soil. Additionally, the residual foam generated
by the flotation process requires further treatment and/or disposal.
Reduction of Radiotoxicity. Mobility, and Volume
This technology effectively separates contaminated soil fines from the clean,
larger soil particles, thus reducing the volume of material requiring further treatment
and/or disposal. However, the foam generated during this process contains elevated
levels of contaminants and requires treatment and/or disposal. While flotation reduces
the volume of the contaminated soil, the residual is highly concentrated and requires
114
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FLOTATION
additional management, since the toxicity and mobility of the original contaminants
are not addressed by this technology.
Short-Term Effectiveness
The organic content of the soil may reduce this treatment's effectiveness. In
addition, clay and silt increase the volume of contaminated material removed in the
generated foam, thus increasing the volume of material requiring additional
treatment.164 Fugitive gas and dust generated during the excavation and grinding of
contaminated soil may pose a threat to workers' health and safety.
Implementability
Although many flotation systems are being developed to address radionuclide-
contaminated soils, none have been tested beyond the bench scale.165 Implementation
of this technology requires intensive knowledge of the soil characteristics, including
particle size and shape distribution; association of radionuclides with particle size;
clay, humus, sand and silt content; and specific gravity, chemical composition, and
mineralogical composition. In addition, suitable flotation agents must be available.166
The residual generated by this technology requires additional treatment and/or
disposal.
Costs
Capital costs for this technology are driven by leasing large capacity flotation
equipment; O&M costs are associated with operating the system for extended periods
of time. Treating and disposing of highly concentrated residuals also add to costs.
2.10.3 Summary
Flotation has been used by the mining industry to separate heavy metals and
radionuclides from ores, and has been tested at the bench scale for reducing the
volume of radionuclide-contaminated soil. Further development is needed to ensure
this technology's effectiveness for radionuclide-contaminated soil. In addition, the
following factors may limit flotation's applicability.
115
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FLOTATION
no reduction in the toxicity or mobility of the radioactive contaminants, may
produce residuals with higher toxicity and mobility;
management of residual may be required;
availability of a suitable flotation agent;
limited demonstration of technology;
organic content and particle size of soil.
Exhibit 2-30 summarizes the data and analyses presented in this profile and can
be used for technology comparison.
Exhibit 2-30: NCR Criteria for Flotation
NCP Criterion
Overall Protectiveness
Evaluation
Preliminary studies indicate that
protectiveness is achieved.
Performance Data
Not yet fully demonstrated.
Preliminary studies indicate that the
volume of contaminated soil can be
reduced by 70 to 90 percent.
Compliance with
ARARs
The requirements of RCRA
LDR and NRC may apply to the
residual waste produced by this
technology.
Performance data such as removal
efficiencies must be assessed in
relation to preremediation
concentrations and cleanup standards
to determine compliance with
ARARs.
Long-Term
Effectiveness and
Permanence
This technology needs further
development to ensure
effectiveness with radionuclide-
contaminated soils.
Residual waste is present in soil
fines.
Bench scale tests and studies indicate
a consistent and successful
segregation of contaminants from
soil.
Residual contamination present in
soil fines requires further treatment
and/or disposal.
Reduction of
Radiotoxicity, Mobility,
or Volume
Does not reduce toxicity or
mobility of contaminants in
residuals.
Separates contaminated soil
fractions (soil fines) from clean
soil fractions (granular soil and
gravel).
Process separates clean and
contaminated soil fractions, thus
reducing the volume of soil requiring
treatment.
Short-Term
Effectiveness
Technology does not pose an
immediate threat.
Potential risk to workers from
fugitive gas and dust during soil
excavation.
Potential risk to workers and/or
nearby community.
Residual waste requires further
treatment and/or disposal.
116
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FLOTATION
Exhibit 2-30: NCR Criteria for Flotation (Cont.)
NCP Criterion Evaluation Performance Data
Implementability
Cost
Several variations of this
technology have been
successfully tested at the bench
scale.
Availability of flotation agents
limits the applicability of this
technology.
Varying capital and O&M costs
may be associated with this
technology and generally depend
on the size of the flotation unit.
Requires excavation of soil and may
require grinding.
Numerous flotation systems are
being tested for radionuclide-
contaminated soil.
O&M costs are lower with larger
systems, however larger systems
increase capital costs.
117
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VITRIFICATION
VITRIFICATION
J
Vitrification involves heating contaminated media to extremely high temperatures,
then cooling them to form a solid mass. Upon cooling, a dense glassified mass remains,
trapping radioactive contaminants. The process can be applied to contaminated soil, sludge,
sediment, mine tailings, buried waste, and metal combustibles. Different devices may be
used, such as plasma torches or electric arc furnaces. Vitrification technologies may be
particularly useful for treating radioactive or mixed waste. An off-gas system may be
required for emissions during vitrification because some organic contaminants will likely be
destroyed and some inorganics, including low melting point radionuclides, will volatilize due
to the high temperatures involved.
Vitrification processes can be performed both in-situ and ex-situ. This section
discusses both processes in detail. Ex-situ processes addressed include: plasma centrifugal
furnace, arc melter vitrification, graphite DC plasma arc melter, plasma fixed hearth, and
thermal plasma processes.
117
-------
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IN-SITU VITRIFICATION
2.11 IN-SITU VITRIFICATION
J
2.11.1 Technology Characterization
Description
In-situ vitrification (ISV) uses an electric current to melt soil or other media at
extremely high temperatures (1,600 to 2,000 °C or 2,900 to 3,650 °F).167
Radionuclides and other pollutants are immobilized within the vitrified glass, a
chemically stable, leach-resistant material similar to obsidian or basalt rock. ISV
destroys or volatilizes most organic pollutants by pyrolysis. A vacuum hood is often
placed over the treated area to collect off-gases, which are treated before release. ISV
is currently available on a commercial scale. Exhibit 2-31 illustrates the general
process involved with In-situ Vitrification.
Electrodes
Off-Gas
Collection
Hood s
Porous X*
Cold Cap
(rocks,
ceramics)
S
\
^o
o
Tl
O ^
D
C3 ^- Jo
Soil Contaminated
with Nuclides
V
Clean Soil
eatment
^^ Surface
"Q
J
j
)
"^Floating
Layer
(rocks
ceramics)
\
Subsidence
Due to
Densification
Exhibit 2-31: In-situ Vitrification
U.S. Environmental Protection Agency,Vitrification Technologies for Treatment of Hazardous and Radioactive Waste,
EPA/625/R-92/002, May 1992.
119
-------
IN-SITU VITRIFICATION
Target Contaminant Groups
ISV may be applicable to a wide range of organics and inorganics,
including radioactive contaminants (i.e., uranium, radium) and asbestos.168
Testing indicates that the process may be used to treat other buried waste,
including containers.169 Vitrification reduces the volume and mobility of the
contaminated materials, but does not affect their radioactivity. Additional
protective measures such as shielding may therefore be required to protect public
health and the environment.
Technology Operating Characteristics
Exhibit 2-32 summarizes the operating characteristics of in-situ
vitrification.
Exhibit 2-32: Technical Characteristics of In-situ Vitrification
Characteristic Description
Destruction and
Removal
Efficiencies (DREs)
Emissions: Gaseous
and Particulate
Process reduces the volume and mobility of contaminants but does not
affect their radioactivity. Volatile radionuclides requiring further
treatment and/or disposal may be released during the process. TCLP
test results show that vitrification reduces leaching significantly. 17°
Process requires air emissions collection system due to volatilized
contaminants. Cesium-137, Sr-90, and tritium may volatilize under
certain conditions.171 Combustible gases may also be produced in
some cases; ignition of these gases could release radionuclides into
the atmosphere.172
Shade, J.W., Thompson, L.E., and Kindle, C.H., In-Situ Vitrification of Buried Waste Sites.
170Shade, J.W., Thompson, L.E., and Kindle, C.H., In-Situ Vitrification of Buried Waste Sites.
Oak Ridge National Laboratory,Technology Evaluation Data Sheets, Part B, Dismantlement - Remedial Action. ORNL/M-
2751/V3/PI.B, September 1993.
172
Thompson, L.E., J.S. Tixier, and J.K. LueyJn-Situ Vitrification: Planned Applications for the Office of Environmental
Restoration, Proceedings ofER O93 Environmental Remediation Conference, Augusta, Georgia (1993).
120
-------
IN-SITU VITRIFICATION
Exhibit 2-32: Technical Characteristics of In-situ Vitrification
Characteristic
Description
Costs: Capital and
O&M
Treatability tests are $25,000 to $30,000, plus analytical fees.
Equipment mobilization/demobilization is $200,00 to $300,000. ISV
costs from $300 to $450 per ton.173
Exhibit 2-32: Technical Characteristics of In-situ Vitrification (Cont.)
Characteristic Description
Reliability
Process Time
Applicable Media
Pretreatment/Site
Requirements
Type and Quantity
of Residuals
Disposal Needs and
Options
Post-Treatment
Conditions
Ability to Monitor
Effectiveness
ISV is commercially available and operating at several DOE sites,
including Hanford, WA and Oak Ridge, TN.
Melt rate of 3 - 5 tons per hour.
Soil, sludge, sediment, mine tailings, some buried waste, incinerator
ash174
ISV requires an on-site electrical distribution system. No excavation
is required, but soil parameters must be evaluated. ISV can only treat
near-surface contamination (within 5-7 meters of the surface).
Construction of an off-gas collection and treatment system is also
required.
Volume reduction of 20% to 50%; air filter scrubber water may
contain partially oxidized organics and volatilized radionuclides (e.g.,
cesium- 137).
Vitrified mass remains in place but may require additional radiation
barriers to protect the public and the environment. Trapped volatile
radionuclides require treatment and/or disposal.
Subsidence occurs due to volume reduction.
The vitrified mass can be tested for TCLP leaching requirements;
radionuclide mobility can be assessed by sampling groundwater
around the perimeter of the vitrified mass; concentrations of volatile
radionuclides can be monitored during the vitrification process;
radiation levels can be monitored at the site after vitrification.
U.S. Department of Defense, Environmental Technology Transfer Committeeftemediation Technologies Screening Matrix and
Reference Guide, Second Edition, NTIS PB95-104782, October 1994.
TJ.S. Environmental Protection Agency,Vitrification Technologies for Treatment of Hazardous and Radioactive Waste,
EPA/625/R-92/002, May 1992.
121
-------
IN-SITU VITRIFICATION
Site Considerations
High soil moisture and salt content can increase electrical needs and cost.
Void volumes and percentages of metals, rubble, and combustible organics must
be considered. ISV is most effective for near-surface contamination although new
approaches may increase treatment depths to 10 meters.175
175
Thompson, L.E., J.S. Tixier, and J.K. Luey/« Situ Vitrification: Planned Applications for the Office of Environmental
Restoration, Proceedings ofER O93 Environmental Remediation Conference, Augusta, Georgia (1993).
122
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IN-SITU VITRIFICATION
2.11.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
Aside from the high levels of electricity used in the process, ISV is
relatively safe for workers and the public no material is extracted, thus exposure
is minimal. Vitrification does not necessarily provide any additional shielding
from radiation, so some form of backfill or cap over the vitrified mass may be
necessary to reduce surface doses in the long-term. An off-gas treatment system
may be necessary to prevent vitrification emissions from escaping into the air;
special care may be required to prevent combustible gas buildup during
vitrification.
Compliance with ARARs
If the waste left in place is characterized as a RCRA hazardous waste, then
RCRA requirements (e.g., surface impoundment regulations) are applicable or
relevant and appropriate. Compliance with other ARARs must be determined on a
site-specific basis.
Long-Term Effectiveness
The vitrified mass is very resilient to weathering, which makes it effective
for long-term containment of waste. Since the material remains on-site, however,
monitoring is required to determine its effectiveness. Because vitrification affects
only the volume and mobility of the waste, additional shielding may be required to
protect against radiation exposure.
Reduction of Radiotoxicity. Mobility, or Volume
Radioactive materials remain immobilized in the vitrified/contaminated
materials mass, preventing migration of these contaminants. Volume reductions
may range from 20 to 50 percent for ISV, and vary widely depending on waste
type.176 The toxicity and volume of the radionuclides are not addressed by this
technology.
U.S. Environmental Protection Agency,Vitrification Technologies for Treatment of Hazardous and Radioactive Waste,
EPA/625/R-92/002, May 1992..
123
-------
IN-SITU VITRIFICATION
Short-Term Effectiveness
Volatile radionuclides (Cs-137, Sr-90, tritium, and others) may be released
during vitrification; these substances should be captured by an off-gas system. If
precautions are not taken, however, ignition of built-up combustible gases could
release radionuclides and other substances into the environment. The radioactivity
of the contaminated materials is not reduced by vitrification.
Implementability
ISV is a proven, commercially available technology. An electrical
distribution system, off-gas treatment system, and process control system are
required for implementation. Since the treatment is entirely in-situ, no offsite
activity is necessary to manage, treat or store waste. ISV can process 3 to 5 tons of
waste per hour; waste can be treated to depths of 5 to 7 meters. Equipment trailers
can be moved within 24 hours to a new spot. Depending on the radioactivity of the
vitrified mass, protective barriers surrounding the mass may be required.
Cost
Initial setup may require an electrical distribution system, off-gas treatment
system, and process control system. At present, these are typically located in
mobile trailers that can be moved from site to site. Electrical demands can be
substantial for each application. The high capital and electric costs may be offset
over the site's life because the long-term stability of the vitrified mass may result in
lower monitoring costs compared to other in-situ stabilization techniques. Also,
the vitrified material is less likely to require future retreatment. Since the
technology treats the material in-situ, no offsite transportation, treatment, storage,
or disposal costs are added, unless the vitrified mass requires removal at a later
date. Costs rise if radiation barriers must be built. Cost estimates for in-situ
vitrification range from $300 - $450 per ton.177
2.11.3 Summary
ISV volatilizes or destroys some organics and immobilizes nonvolatile
radionuclides. The high temperatures rapidly volatilize some organic compounds
and volatile radionuclides, including Cs-137, Sr-90, and 3 tritium. Control of these
off-gases, as well as the high voltage used, present potential health and safety risks.
U.S. Department of Defense, Environmental Technology Transfer Committeeftemediation Technologies Screening Matrix and
Reference Guide, Second Edition, NTIS PB95-104782, October 1994.
124
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IN-SITU VITRIFICATION
In general, the process is highly complex and implementation is difficult. The
process works best on homogeneous soils since different strata may interfere with
the extent (i.e., depth in soil) to which the process is effective. ISV reduces the
volume and mobility of radionuclides but does not reduce their radioactivity.
Therefore, protective barriers that limit exposure to radioactive emissions may still
be required at some sites. The following factors may impact the applicability and
effectiveness of this process:
soil moisture and content;
contamination depth;
volatilization of some radionuclides;
radiation emissions require additional management.
Exhibit 2-33 summarizes the data and analyses presented in this profile and
can be used for technology comparison.
Exhibit 2-33: NCP Criteria for In-situ Vitrification
NCR Criterion
Overall
Protectiveness
Evaluation
Limited overall
protectiveness at
site; however
prevents migration
of contaminants.
Performance Data
Demonstrated
Vitrified mass is stable for
geologic time periods.
Does notshield or eliminate
radiation effects.
Compliance
withARARs
RCRA
requirements may
be applicable.
Compliance with
other ARARs
determined on site-
specific basis.
Waste remains in place.
125
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IN-SITU VITRIFICATION
Exhibit 2-33: NCR Criteria for /n-s/tu Vitrification (Cont.)
NCR Criterion
Reduction of
Radiotoxicity,
Mobility, or
Volume
Evaluation
Does not reduce
the radioactivity
of contaminants.
Reduces toxicity
and volume of
organic
contaminants.
Reduces mobility
of inorganic
contaminants
(e.g.,
radionuclides,
heavy metals).
Performance Data
May result in the removal and/or
destruction of organic
contaminants.
Effectively immobilizes inorganics
(e.g., radionuclides, heavy metals).
Long-Term
Effectiveness and
Permanence
Needs further
development to
ensure
effectiveness.
Models predict that vitrified waste
could immobilize contaminants for
1000 to 1 mi 11 ion years.178
Short-Term
Effectiveness
Requires an off-
gas collection
system to
prevent release
of volatile
radionuclides
and build-up of
combustible
gases.
Relatively short
process time.
Volatile substances (Pb.Cd,
possibly Cs) could contaminate
other components of the treatment
system.179
Implementability
Difficult to
implement and
control.
May interfere
with current site
activities.
Electrical distribution and off-gas
control system needed.
Treatment of 3 to 5 tons/hour to a
depth of 5 to 7 meters.
Subsidence occurs due to volume
reduction.
Radiation barriers may need to be
constructed.
U.S. Environmental Protection Agency Approaches for the Remediation of Federal Facility Sites Contaminated with Explosive
or Radioactive Waste, EPA/625/R-93/013, September 1993.
179
Ibid.
126
-------
Exhibit 2-33: NCR Criteria for /n-s/tu Vitrification (Cont.)
NCR Criterion
Evaluation
Performance Data
Cost
High
High capital costs.
-------
EX-SITU VITRIFICATION
128
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EX-SITU VITRIFICATION
2.12 EX-SITU VITRIFICATION
J
2.12.1 Technology Characterization
Description
Ex-situ vitrification technologies generally involve applying existing
technologies (e.g., metals processing) to new purposes. Ex-situ vitrification applies
heat to destroy some contaminants (e.g., organics) and immobilize others (e.g.,
radioactive waste) into a dense, glassified mass. Heating devices used include
plasma torches and electric arc furnaces. Ex-situ vitrification is useful for treating
radioactive and mixed wastes. While the final nonleaching glassy solid product can
be stored without further treatment, vitrification does not reduce the waste's
radioactivity. Vitrified waste must therefore be stored in facilities that protect the
public from radiation exposure.178
Ex-situ vitrification technologies vary in design and application. For
example, some processes use a plasma torch technology similar to that used to refine
titanium. In this process, waste is fed into a rotating hearth; the waste and molten
material are held against the side by centrifugal force. During the rotation, the
waste moves through plasma generated by a stationary torch. To remove the molten
material from the furnace, the hearth's rotation slows and the slag flows through a
bottom opening.179 Effluent gases are generally kept in a separate container where
high temperatures combust/oxidize the contents.180
Other ex-situ vitrification processes use electricity, such as an arc furnace
that contain carbon electrodes, cooled side walls, a continuous feed system, off-gas
treatment system, and slag and metals tapping capability.181 In this process, waste
is fed into the top of a refractory chamber where it is heated to temperatures greater
Hoffeiner, W., Chrubasik, A., Eschenbach, R.C..Volume Reduction and Vitrification of Nuclear Waste with Thermal Plasmq
Proceeds of the 1993 International Conference on Nuclear Waste Management and Environmental Remediation, Volume 3, 1993.
179U.S. Department of Energy, Office of Environmental Management Office of Technology DevelopmentBur/ed Waste
Integrated Demonstration, DOE/EM-0149P, March 1994
Hoffeiner, W., Chrubasik, A., Eschenbach, R.C..Volume Reduction and Vitrification of Nuclear Waste with Thermal Plasmq
Proceeds of the 1993 International Conference on Nuclear Waste Management and Environmental Remediation, Volume 3, 1993.
181U.S. Department of Energy, Office of Environmental Management, Off ice of Technology DevelopmentBuried Waste
Integrated Demonstration, DOE/EM-0149P, March 1994
129
-------
EX-SITU VITRIFICATION
than 1500°C by carbon electrodes. The weight of the waste pushes the molten slag
through a bottom opening into a cooling chamber, where slag and molten metals
can be separated. Volatile substances, including some radionuclides, emitted
during the process are treated in an off-gas collection and treatment system.182
Exhibit 2-34 illustrates the general process associated with Ex-situ Vitrification.
Exhaust
Gas
Power Input
o
Soil
Contaminated
with Radioactive
Waste
Limestone
Soda Ash
(if needed
Exhibit 2-34: Ex-situ Vitrification
Target Contaminant Groups
These processes can treat and vitrify hazardous, radioactive (both low-level
and transuranic wastes - elements heavier than uranium), and mixed waste.183 Ex-
situ vitrification has been used with radionuclides, combustibles, inorganic
materials, and metals.
U.S. Environmental Protection Agency,Superfund Innovative Technology Evaluation Program: Technology Profiles, Seventh
Edition EPA/540/R-94/526, November 1994.
183U.S. Department of Energy, Office of Environmental Management Office of Technology DevelopmentBur/ed Waste
Integrated Demonstration, DOE/EM-0149P, March 1994
130
-------
EX-SITU VITRIFICATION
Technology Operating Characteristics
One electric arc vitrification unit currently in use can process a nominal 1.5
tons per hour of buried waste-type feeds and soil. This technology has been used
in the steel industry to process excess of 105 tons per day.184 Some ex-situ
vitrification plants are very compact, are flexible in process control, and are highly
automated.185 Additionally, material of different forms can be fed into furnaces.
For example, liquids may be pumped; shredded waste can be screw fed; and steel
drums can be directly inserted by robotics, opened, and completely melted inside
the furnace.186
Technology Operating Characteristics
Exhibit 2-35 summarizes the operating characteristics of ex-situ
vitrification.
Exhibit 2-35: Technical Characteristics of Ex-situ Vitrification
Characteristic
Description
Destruction and
Removal Efficiencies
(DREs)
Ex-situ vitrification significantly reduces the mobility and
volume of radionuclide-contaminated waste (volume reductions
up to 65% with some waste), but does not reduce their
radioactivity; volatile radionuclides trapped during the process
require further treatment and/or disposal.187
Emissions: Gaseous
and Particulate
Since vitrification processes may cause polluted flue gases (i.e.,
containing radionuclides),188 appropriate gas collection systems
must be used to minimize emissions. Some processes use a wet
gas cleaning system, producing extremely clean off-gas.189
Excavation of contaminated materials could cause fugitive gas
and dust emissions of radionuclides.
Hoffeiner, W., Chrubasik, A., Eschenbach, R.C..Volume Reduction and Vitrification of Nuclear Waste with Thermal Plasmq
Proceeds of the 1993 International Conference on Nuclear Waste Management and Environmental Remediation, Volume 3, 1993.
18W
187U.S. Department of Energy, Office of Environmental Management Office of Technology Development, Technology
Catalogue, First Edition, DOE/EM-0138P, February 1994.
Hoffeiner, W., Chrubasik, A., Eschenbach, R.C..Volume Reduction and Vitrification of Nuclear Waste with Thermal Plasmq
Proceeds of the 1993 International Conference on Nuclear Waste Management and Environmental Remediation, Volume 3, 1993.
ls9Ib,d.
131
-------
EX-SITU VITRIFICATION
Exhibit 2-35: Technical Characteristics of Ex-situ Vitrification (Cont.)
Characteristic
Description
Costs: Capital and
O&M
Reliability
Process Time
Applicable Media
Pretreatment/Site
Requirements
Type and Quantity of
Residuals
The cost to develop and build an ex-situ system (electric arc
furnace) that can process 5 tons per hour could cost from $50 to
$100 million. 19° Operating costs could range from $400 to 500
per ton, to $1,900 per ton. 191'192
These processes are proven industrial technologies. Testing is
required to determine thermal properties of waste constituents.
TCLP requirements are generally met. 193 Vitrified mass has
high strength properties; actual values will vary with cooling
method (e.g., quench or air cooled), use of fluxing agents, and
composition of soil or other media.
Some ex-situ vitrification processes can process 3 to 5 tons per
,194
day.
Buried waste, debris, soils, metals (including radionuclides),
combustibles, and sludges
Requires excavation. High energy use requires sufficient
electric or fuel sources. May require addition of suitable glass-
making substrates.
Some volatile heavy metal and radioactive contaminants may
volatilize and require treatment in an off-gas system. 195
Vitrified mass contains radioactive material that requires final
handling and disposal.
\J.S. Environmental Protection Agency,Superfund Innovative Technology Evaluation Program: Technology Profiles, Seventh
Edition , EPA/540/R-94/526, November 1994.
Oak Ridge National Laboratory,Oa£ Ridge National Laboratory Technology Logic Diagrams, Volume 2, Part B, Remedial
Action, ORNL/M-2751/V2/PI.B, September 1993.
U.S. Department of Defense, Environmental Technology Transfer Committeeftemediation Technologies Screening Matrix and
Reference Guide, Second Edition, NTIS PB95-104782, October 1994.
TJ.S. Department of Energy, Office of Environmental Management Office of Technology Developmenl^Hnerf Waste Integrated
Demonstration, DOE/EM-0149P, March, 1994.
U.S. Department of Defense, Environmental Technology Transfer Committee, Remediatioffechnologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
132
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EX-SITU VITRIFICATION
Exhibit 2-35: Technical Characteristics of Ex-situ Vitrification (Cont.)
Characteristic
Description
Disposal Needs and
Options
Post-Treatment
Conditions
Ability to Monitor
Effectiveness
Ex-situ vitrification products are disposable without further
stabilization treatment, but must be safely stored to prevent
radiation exposure.
Excavation requires backfilling with suitable materials.
Vitirified waste requires proper storage.
Vitrified waste can be tested for TCLP leaching. Radiation can
be monitored during ex-situ vitrification and at the disposal site.
Groundwater monitoring is required at the disposal site.
Site Considerations
Ex-situ vitrification applies to a broad range of solid media (e.g., debris,
soil, etc.). The composition of the radionuclide-contaminated media may affect the
strength properties of the vitrified material. In some cases glass-making materials
(e.g., sands high in boro-silicates) may have to be added to the waste. Ex-situ
vitrification has been used to treat many different types of radioactive waste,
including transuranic (TRU) waste.196
2.12.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
Although these technologies have not been fully demonstrated,
protectiveness has been achieved in preliminary studies. Ex-situ vitrification
immobilizes radioactive waste and volatilizes and/or destroys the organics in
mixed waste. Because radioactivity is still present, shielding from vitrified masses
is necessary to reduce or eliminate possible exposure. Additionally, some
processes may produce polluted flue gases which require further treatment.
196U.S. Department of Energy, Office of Environmental Management, Off ice of Technology Development, Technology
Catalogue, First Edition, DOE/EM-0138P, February 1994.
133
-------
EX-SITU VITRIFICATION
Excavation of contaminated soils could cause radiation exposure to workers from
fugitive gas and dust emissions.197
Compliance with ARARs
Ex-situ vitrification treatments must result in residual soil levels that comply
with NRC and RCRA requirements. Ex-situ vitrification has been found, in some
cases, to fulfill stringent environmental requirements.198 Compliance with other
ARARs needs to be determined on a site-specific basis.
Long-Term Effectiveness
Past demonstrations and studies indicate contaminants are consistently and
successfully destroyed and/or immobilized in applicable media. Vitrified masses
have high strength and generally meet EPA TCLP testing requirements. Long-
term monitoring is required after disposal of vitrified masses.
Reduction of Radiotoxicity. Mobility, or Volume
Many ex-situ vitrification technologies have reduced off-gas flows, high
organic destruction efficiency, high waste volume reduction, and the ability to treat
almost any type of waste.199 Mobility is greatly reduced for contaminants trapped
within the vitrified mass, however the radioactivity of radionuclide contaminants is
not reduced. Volume reductions may range as high as 65 percent for ex-situ
vitrification, varying widely depending on waste type.200
Short-Term Effectiveness
Excavation and/or handling of contaminated media may increase the risk to
workers and surrounding populations. The high automation typical of ex-situ
vitrification processes significantly reduces risk to workers and negative
Hoffeiner, W., Chrubasik, A., Eschenbach, R.C..Volume Reduction and Vitrification of Nuclear Waste with Thermal Plasmq
Proceeds of the 1993 International Conference on Nuclear Waste Management and Environmental Remediation, Volume 3, 1993.
199U.S. Department of Energy, Office of Environmental Management, Off ice of Technology DevelopmentSt/nec1 Waste
Integrated Demonstration, DOE/EM-0149P, March 1994.
200U.S. Department of Energy, Office of Environmental Management, Off ice of Technology Development, Technology
Catalogue, First Edition, DOE/EM-0138P, February 1994.
134
-------
EX-SITU VITRIFICATION
environmental impacts.201 In some cases, however, polluted flue gases may need
further treatment.
Hoffeiner, W., Chrubasik, A., Eschenbach, R.C..Volume Reduction and Vitrification of Nuclear Waste with Thermal Plasmq
Proceeds of the 1993 International Conference on Nuclear Waste Management and Environmental Remediation, Volume 3, 1993.
135
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EX-SITU VITRIFICATION
Implementability
Demonstrations and studies at several sites (Oakridge, TN, Washington,
DC)202 indicate that ex-situ vitrification technologies can be implemented without
significant difficulties. Contaminated materials (e.g., debris, soils) must first be
excavated, however. Also, a high degree of specialized skill and training is
required.
Cost
Capital costs for ex-situ vitrification is high due to its heavy use of energy
and the need to transport radioactive waste. Due to the stability of the vitrified
product, however, long-term maintenance costs are reduced, even if additional
containment shielding is required. Approximate overall costs range from $400 to
500 per ton, to $1,900 per ton.203'204
2.12.3 Summary
Ex-situ vitrification technologies have been demonstrated at several federal
facilities contaminated with radioactive waste. Ex-situ vitrification can treat many
different forms of radioactive waste and forms a strong, stable, leach-resistant
product that is more easily handled. However, vitrification does not affect the
radioactivity of the final product; disposal at a site with suitable radiation barriers
is thus necessary. The process may also expose workers or local populations to
radioactive contaminants during excavation of contaminated sites. Further, volatile
radionuclides must be collected and treated during vitrification. Ex-situ
vitrification technologies are still largely in the developmental stages, thus more
research on the treatment of radioactive waste needs to be conducted. Factors that
may impact the applicability and effectiveness of the process include the
following:
radioactive constituents of waste;
properties of contaminated media;
risks posed to workers and local communities from excavation and
transport of radioactive waste;
202U.S. Department of Energy, Office of Environmental Management, Off ice of Technology Development,M/n/mum/4cW/t/Ve
Waste Stabilization, Technology Summary, DOE/EM-0124P, February 1994.
Oak Ridge National Laboratory,Oak Ridge National Laboratory Technology Logic Diagrams, Volume 2, Part B, Remedial
Action, ORNL/M-2751/V2/PI.B, September 1993.
TJ.S. Department of Defense, Environmental Technology Transfer Committeeflemediation Technologies Screening Matrix and
Reference Guide, Second Edition, NTIS PB95-104782, October 1994.
136
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EX-SITU VITRIFICATION
disposal options for radioactive vitrified masses.
Exhibit 2-36 summarizes the data and analyses presented in this profile. It
can be used for technology comparison.
Exhibit 2-36: NCP Criteria for Ex-situ Vitrification
NCP Criterion
Overall Protectiveness
Evaluation
Reduces volume and
mobility of radioactive
waste but proper disposal
requires adequate
radiation shielding.
Risks posed to workers
and communities must be
considered.
Performance Data
Technologies are in various
stages of demonstration.
Compliance with
ARARs
Vitrified mass would
have to comply with
LNRC and RCRA LDR
requirements.
Compliance with other
ARARs must be
determined on a site-
specific basis.
Performance data, such as
removal efficiencies, must
be assessed in relation to
preremediation
concentrations and cleanup
standards to determine
compliance with ARARs.
Long-Term
Effectiveness and
Permanence
Past demonstrations and
studies indicate that long-
term effectiveness and
permanence are achieved
with these technologies.
Additional shielding to
prevent exposure to
radiation is required
during handling/disposal.
Polluted flue gases may
need further treatment.
Demonstrations and studies
indicate radioactive
contaminants are
consistently and
successfully immobilized in
a vitrified mass.
Radioactivity is affected.
Reduction of
Radiotoxicity,
Mobility, or Volume
Reduces toxicity of
certain contaminants
(e.g., organics) and
successfully immobilizes
those that cannot be
destroyed (e.g.,
radionuclides).
Does not reduce toxicity
of radionuclides.
Demonstrations and studies
indicate radioactive
contaminants are
consistently and
successfully immobilized in
a vitrified mass.
137
-------
Exhibit 2-36: NCP Criteria for Ex-situ Vitrification (Cont.)
NCP Criterion
Short-Term
Effectiveness
Evaluation
Excavation and
transportation of
contaminants pose an
immediate threat.
Fugitive gas and dust
generated during
excavation may expose
workers and the
surrounding community
to health and safety risks.
Radioactivity is not
shielded in final product.
Performance Data
Potential risk to workers or
nearby community.
Additional containment and
disposal is required.
Implementability
Technologies can be
implemented without
difficulty.
Demonstrations and studies
indicate that
implementation is not
significantly difficult.
Cost
The costs of treating
radioactively
contaminated waste using
ex-situ vitrification
depend on excavation
costs, transportation
costs, electricity
requirements, the types
of contaminants to be
treated, and disposal fees.
Costs are considered
high.205
-------
SECTION III
LIQUID MEDIA TECHNOLOGY PROFILES
137
-------
-------
CHEMICAL SEPARATION
CHEMICAL SEPARATION
J
Chemical separation technologies for liquid media involve processes that
separate and concentrate radioactive contaminants from groundwater, surface, or waste
water. Process residuals such as filters, filter cakes, carbon units, and ion exchange
resins require further treatment, storage, or disposal. Extractability rates of the
different chemical separation technologies vary considerably based on the types and
concentrations of contaminants, as well as differences in methodology. Whether these
technologies can be implemented is determined by site-specific factors and their
applicability must be determined on a site-by-site basis.
Technologies in this category include: ion exchange and chemical precipitation
using carbonates, sulfates, sulfides, or lime and other hydroxides.
139
-------
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CHEMICAL SEPARATION
3.1 ION EXCHANGE &
CHEMICAL PRECIPITATION
3.1.1 Technology Characterization
Chemical separation technologies for groundwater include ion exchange
and chemical precipitation. Chemical separation technologies are generally ex-situ
and require the construction and operation of a groundwater extraction and
delivery system; they generate a treated effluent and a contaminated residual that
requires further treatment or disposal.
Because there are many similarities between the two technologies,
discussion about them has been combined for the target contaminant groups, site
considerations, and NCP criteria evaluation.
Description
Ion exchange, a fully developed chemical separation process, is highly
efficient in reducing radionuclide and inorganic metal levels in liquid waste
streams to levels suitable for effluent discharge. Ion exchange has been identified
as the Best Available Technology (BAT) for the removal of radium-226, radium-
228, and uranium. This technology separates and replaces radionuclides in a waste
stream with relatively harmless ions from a synthetic resin or natural zeolite (for
strontium and cesium). Resins consist of an insoluble structure with many ion
transfer sites and an affinity for particular kinds of ions. Resins are either acid-
cationic (for removing positively charged ions) or base-anionic (for removing
negatively charged ions); resins used for radioactive liquid waste are often either
hydrogen (H+) or hydroxyl (OH-). Resins must be regenerated by exposing them
to a concentrated solution of the original exchange ion, while zeolites are stored as
solid waste.
A typical ion exchange unit is in a fixed bed with a vertical cylindrical
pressure vessel. It contains one or more meters of exchange resin (either cationic
or anionic) which is in contact with water in both a downflow and backwash
upflow. Alternatively, some ion exchange units send water through a mixed-bed,
which contains both cationic and anionic resins in the same bed.
Ion exchange significantly reduces contaminant mobility by immobilizing it
in the exchange media, but does not affect the radiotoxicity of the contaminant
itself. It is most effective when the waste stream is in the ionic form; nonionic
waste streams or waste streams with suspended solids must be pretreated. Both
141
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CHEMICAL SEPARATION
concentrated waste removed from the resin and spent resin itself must be treated,
stored, or disposed of. Also, this technology's effectiveness depends on the pH,
temperature, and flow rate of the waste material, and the resin's selectivity and
exchange capacity. If more than one radioactive contaminant is present, more than
one treatment process may be required.
Exhibit 3-1 illustrates the general process involved with ion exchange.
Column
Filtration
Unit
Ion
Exchange
Resins
Surface
Effluent =
Clean Water
Extraction
Well
Exhibit 3-1: Ion Exchange Diagram
Chemical precipitation converts soluble radionuclides to an insoluble form
through a chemical reaction or through changing the solvent's composition to diminish
solubility. Precipitation adds a chemical precipitant to the radionuclide-containing
aqueous waste in a stirred reaction vessel. Solids are separated by settling in a
clarifier; flocculation, with or without a chemical coagulant or settling aid, may be
used to enhance their removal. Commonly used precipitants include carbonates,
sulfates, sulfides, lime and other hydroxides. The amounts of radionuclides that can
be removed from a solution depends on the precipitant and dosage used, the
concentration of radionuclides present in the aqueous waste, and the pH of the
142
-------
CHEMICAL SEPARATION
solution. Maintaining optimum pH levels within a relatively narrow range is usually
necessary to achieve adequate radionuclide precipitation.
Either batch reactors or continuous flow designs can be used. Batch reactors
are generally favored for flows up to 50,000 gallons per day and usually operate with
two parallel tanks. Each tank acts as a flow equalizer, reactor, and settler, thus
eliminating the need for separate equipment for each step. Continuous systems have a
chemical feeder, flash mixer, flocculator, settling unit, filtration unit (if used), and
control system for feed regulation.
Exhibit 3-2 illustrates the general process involved with chemical precipitation.
Ground Water
-Reagent Polymer
-agent P
i' y
I I I A
pH Adjustment Flocculation ,
and Reagent Addition
________^___
Filtrate
Solids to
Disposal
I
I Thickener
. Overflow
Sludge
>. Effluent
x^
Clarification
Sludge
Thickening
Exhibit 3-2: Chemical Precipitation Diagram
Source: Balaso, C.A., et al., 1986. Soluble Sulfide Precipitation Study, Arthur D. Little, Inc., Final
Report to USATHAMA, Report No. AMXTH-TE-CR-87106.
143
-------
CHEMICAL SEPARATION
Operating Characteristics
The expected ion exchange removal rates for radium and uranium are 65
percent to 97 percent and 65 percent to 99 percent, respectively. The range of removal
of beta emitters such as cesium-137 and strontium-89 are 95 percent to 99 percent.206
When ion exchange was implemented on a waste water stream at Hanford, an initial
uranium concentration of 0.1 kg/m3 was reduced by 94 percent after eight exchange
cycles (5-7 days per cycle) with an approximate uranium loading of 0.035 kg/kg
commercial resin.207'208
Resins are relatively more expensive than other adsorption reagents such as
carbon, but can achieve higher degrees of selectivity than activated carbon. Cost
(capital plus operating) for ion exchange is estimated to be $5 to $10 per 1,000 gallons
of liquid waste.209 Operating and maintenance costs are also associated with storing the
treatment process waste.
Chemical precipitation was jar-tested on uranium-contaminated pond water,
with the following results: 80 percent removal with a dose of 10 mg/L or more of
ferric sulfate at pH 10, and with 20 mg/L or more at pH 6; 92 percent to 93 percent
removal with a dose of 20-25 mg/L of ferrous sulfate at pH 10; and 95 percent
removal with a dose of 10 mg/L of alum at pH 10.210
There are no available cost data on chemical precipitation for radionuclides.
Target Contaminant Groups
Chemical separation effectively reduces high levels of radionuclides, especially
radium, and uranium, and dissolved metals from groundwater, surface water, and other
aqueous waste streams, including extractants resulting from other chemical separation
processes. Reagents, filters, and resins must be selected on a site-specific basis for the
particular radionuclides present.
Site Considerations
206
U.S. Environmental Protection Agency, EPA625/R-93/013, Approaches for the Remediation of Federal Facility Sites Contaminated with
Explosive or Radioactive Waste, 1993
207
U.S. Department of Energy, Office of Environmental Restoration£)ecommm!o«mg Handbook, DOE, EM-0142P, March 1994.
208
Balaso, C.A., et al., 1986. Soluble Sulfide Precipitation Study, Arthur D. Little, Inc., Final Report to USATHAMA, Report No. AMXTH-TE-
CR-87106.
209Oak Ridge National Laboratory,Technology Evaluation Data Sheets, Part B, Dismantlement - Remedial Action ORNL/M-
2751/V3/Pt. B, September 1993.
210Sorg, Thomas J., "Methods for Removing Uranium From Drinking Water," July 1988.
144
-------
CHEMICAL SEPARATION
Characteristics such as contaminant type and concentration should be well
defined to accurately predict the performance of the chemical separation technology.
The presence of multiple radionuclides could impact the technology's effectiveness.
Ion exchange treatment is effective only for liquid waste streams that are in
ionic form. Nonionic forms (insoluble particles, colloids, and neutral molecules and
complexes) require pretreatment. Pretreatment may also be required to remove solids,
modify the pH of the influent stream for optimum removal efficiencies, or remove
competing ions.
3.1.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
These technologies significantly reduce the volume of contaminants in the
liquid medium, the toxicity of the liquid medium, but not the mobility of the
contaminants remaining in the liquid medium. The processes yeild purified liquid
medium and the contaminated process residuals which can be stored, further
processed, or disposed of.
Compliance with ARARs
The requirements of RCRA LDRs may apply to the residual waste produced.
Aqueous discharges must comply with MCLs or NPDES discharge limits.
Long-Term Effectiveness
Both technologies reduce contamination in liquid waste streams. Continued
testing will improve efficiency.
Potential risks are reduced by removing the contaminants of concern and by
placing the treated residuals in a controlled environment. However, the concentrated
stream of waste removed from the ion exchange resin and precipitated solids requires
treatment, storage, or disposal. Spent ion exchange resin can be rigorously eluted to
lower its radionuclide content before disposal and can be incorporated into cement for
storage or disposal.
145
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CHEMICAL SEPARATION
Reduction of Radiotoxicity. Mobility, or Volume
These technologies significantly reduce contaminant mobility and the volume it
occupies, but not its radiotoxicity. The processes yield a large volume of purified
solution and concentrated residuals that can be stored or disposed of. Residuals from
ion exchange include brine waste, caustic or acid solution (depending on type of
regeneration used), and resins containing radionuclides.
Short-Term Effectiveness
A safety consideration for workers during ion exchange is radiolytic
byproducts, including benzene derivatives produced when the resin is placed in a
radioactive environment. A small amount of hydrogen gas formed in the presence of
organic materials can be captured by an off-gas treatment system. Toxic hydrogen
sulfide gas may be generated during sulfide precipitation. This gas can be minimized
by maintaining the proper pH and an off-gas treatment system.
Implementability
These technologies are fully developed and have been applied to waste streams
contaminated with radionuclides and metals. Laboratory-scale tests should be
conducted to select the best ion exchange materials and systems for each specific
cleanup. A monitoring system can record activity, pH, conductivity, and total
suspended solids for the liquid being processed. Residuals and spent resins require
disposal or storage. Chemical precipitation treatability testing should be conducted to
determine the appropriate selection of reagents and dosages.
Cost
Ion exchange cost (capital plus operating) is estimated to be $5 to $10 per
1,000 gallons of liquid waste. Operating and maintenance costs are also associated
with storing the treatment process waste.211
There are no available cost data on radionuclide precipitation. However,
capital cost estimates for 75- and 250-liters-per-minute packaged metals precipitation
systems are approximately $85,000 and $115,000, respectively. Operating costs are
typically in a range from $0.08 to $0.18 per 1000 liters of groundwater containing up
to 100 mg/L of metals.212
211Oak Ridge National Laboratory,Technology Evaluation Data Sheets, Part B, Dismantlement-Remedial Action, ORNL/M-27511
V3/PartB, September 1993.
212U.S. Department of Defense, Environmental Technology Transfer CommiU&eRemediation Technologies Screening Matrix and
Reference Guide Second Edition, October 1994.
146
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CHEMICAL SEPARATION
3.1.3 Chemical Separation Summary
Chemical separation is useful for reducing high levels of inorganic metal and
radionuclide contaminants from aqueous waste streams. However, these technologies
generate either a concentrated stream of waste removed from the ion exchange resin or
precipitated solids, which require treatment, storage, or disposal. In addition, the ion
exchange process works only on liquid waste streams in ionic form; nonionic waste
streams require pretreatment.
The applicability and effectiveness of chemical separation may be affected by
the following factors:
the physical and chemical properties (e.g. temperature, pH, flow
rate) of the waste material;
a combination of elements in the waste stream; a media with
more than one radioactive contaminant may require more than
one treatment process;
for ion exchange, the physical and chemical properties (e.g.
exchange capacity, ionic selectivity, ionic exchange kinetics) of
the exchange resin;
efficiency of chemical precipitation depends on adequate solids
separation;
precipitation reagent addition must be carefully controlled to
prevent unacceptable concentrations in treatment effluent.
Treatability studies should be conducted to select the best ion exchange materials
and to determine the best operating parameters for chemical precipitation.
Exhibit 3-3 summarizes the data and analyses presented in this profile and can be
used to compare these and any other technologies.
NCP Criterion
Exhibit 3-3: NCP Criteria for Chemical Separation
Evaluation Performance Data
Overall Protectiveness
Protects human health and
the environment by
reducing contaminant
levels in liquid waste
streams and thus potential
risks due to external
exposure and direct
contact.
Fully developed
Useful for reducing inorganic
metal and radionuclide levels of
liquid waste streams to effluent
levels suitable for discharge.
147
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CHEMICAL SEPARATION
Exhibit 3-3: NCP Criteria for Chemical Separation (Cont.)
NCP Criterion Evaluation Performance Data
Compliance with ARARs
Requirements of RCRA
LDRs, CWA, and NRC
may apply to the effluent
and residual waste.
Performance data, such as
removal efficiencies, must be
assessed in relation to pre-
remediation concentrations and
cleanup standards to determine
compliance with ARARs.
Reduction of Radiotoxicity,
Mobility, or Volume
Does not reduce
radioactivity ortoxicity.
Reduces mobility of
contamination through
storage or disposal of
residuals
Volume occupied by the
hazardous or radioactive
component is reduced
MCLs, CWA, and NRC
requirements will also apply to
treated water.
Ion exchange is expected to
remove 65-97% radium and 65-
99% uranium.213
Chemical precipitation proved
80% uranium removal using
ferric sulfate, 92-93% uranium
removal using ferrous sulfate; and
95% uranium removal using
alum.214
Long-Term Effectiveness
and Performance
Demonstrated to reduce
contamination of liquid
waste-streams, including
removal of radionuclides
and metals.
Potential threat due to
long-term storage of
waste.
Continued testing will
improve efficiency.
A monitoring system can be used
to record activity, pH,
conductivity, and total suspended
solids for the processed liquid.
213U.S. Environmental Protection Agency, Office of Research and Developmentjlpproaches for the Remediation of Federal Facility
Sites Contaminated with Explosive or Radioactive Waste, EPA/625/R-93/613, September 1993.
214Sorg, Thomas J. "Method for Removing Uranium From Drinking Water," July 1988.
148
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CHEMICAL SEPARATION
Exhibit 3-3: NCP Criteria for Chemical Separation (Cont.)
NCP Criterion Evaluation Performance Data
Short-Term Effectiveness
Potential health and safety
risk to workers from off-
gases and handling of
treatment residuals.
Ion exchange requires an off-gas
treatment system for hydrogen
gas.
Ion exchange resin placed in a
highly radioactive environment
produces radiolytic byproducts.
Implementability
Applies to liquid waste
only.
To operate efficiently,
specific conditions for
physical and chemical
properties of the waste
material must be met.
Disposal or storage
facilities are needed for
resins or residuals.
Pretreatment required for
nonionic forms of waste and to
remove solids or competing ions
from waste.
Laboratory-scale tests should be
conducted to select the best
materials and systems specific to
each cleanup.
Treatability testing for chemical
precipitation should be conducted
to determine the proper reagents
and dosages for radionuclides.
Cost
Capital and O&M costs
are encumbered with
specific treatment
conditions and handling of
residuals.
Capital and operating costs for
ion exchange range from $5 to
$10 per 1000 gallons.
Chemical precipitation capital
and operating cost estimates are
highly site specific.
149
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PHYSICAL SEPARATION
PHYSICAL SEPARATION
J
Physical separation technologies for liquid media separate contaminated media
into clean and contaminated fractions by taking advantage of the contaminants'
physical properties.
Contaminants are either solvated by the liquid media (i.e., one molecule of the
contaminant surrounded by many molecules of the liquid) or are present as
microscopic particles suspended in the solution. The physical separation of the
radionuclides from the liquid media results in "clean" liquid and a contaminated
residue that requires further handling, treatment, and/or disposal. These residuals may
take the form of a sludge, filter cake, or carbon adsorption unit. Physical separation
technologies can be applied to a variety of liquid media, including groundwater,
surface water, and slurried sludge or sediment.
This profile addresses the following technologies: membrane filtration (reverse
osmosis and microfiltration), carbon adsorption, and aeration.
151
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PHYSICAL SEPARATION
3.2 MEMBRANE PROCESSES,
CARBON ADSORPTION,
AND AERATION
3.2.1 Technology Characterization
Physical separation technologies for liquid media treatment include membrane
processes, liquid phase carbon adsorption and aeration. The technologies are ex-situ
processes and require the construction and operation of a ground-water extraction and
delivery system. They generate a treated effluent waste stream of which the volume
and type depend on the technology.
Because there are many similarities among these technologies, discussion about
them has been combined for the target contaminant groups, site considerations, and
NCP criteria evaluation.
Description
Membrane filtration uses a semipermeable membrane to separate dissolved
radionuclides or solid radionuclide particles in liquid media (e.g., groundwater,
surface water) from the liquid media itself. Generally, some form of pretreatment
(such as filtration of suspended solids) is required in order to protect the membrane's
integrity. Water flow rate and pH should be controlled to ensure optimum conditions.
The effectiveness can easily be monitored by sampling the effluent and residuals.
Two types of membrane processes are reverse osmosis and microfiltration.
Reverse osmosis uses a selectively permeable membrane that allows water to
pass through it, but which traps radionuclide ions on the other side of the membrane.
Normally, osmotic pressures would draw water to the dissolved ions. But high
pressure applied to the solution forces water with lower ion concentrations through
the membrane. Reverse osmosis is affected by the size and charge of the ion being
treated. Because radium and uranium ions are large and highly charged, reverse
osmosis is particularly effective at removing these dissolved radionuclides from
contaminated solutions.
Micro and ultra filtration rely on the pore size of the membrane, which can
be varied to remove particles and molecules of various sizes. Micro and ultra
filtration processes generally work best for separating very fine particles (0.1-0.001
microns) from the liquid. This process is illustrated in Exhibit 3-4.
153
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PHYSICAL SEPARATION
Makeup Water
1
| Filter Feed |
P""P I
Slurry
Pump
Soil Contaminated
with Radioactive
Waste
Spray
Water
Precoat Filter
1
>
>
Treated
Water
Sludge and Spent
Precoat Material to
Disposal
Treated water
to Discharge
or Recharge
Exhibit 3-4: Microfiltration Diagram
Liquid phase carbon adsorption pumps groundwater through a series
of vessels containing activated carbon, to which dissolved contaminants
adsorb215 (see Exhibit 3-5). Activated carbon is an effective adsorbent because
of its large surface to volume ratio. When the concentration of contaminants in
the effluent exceeds a certain level, the carbon can be regenerated in place;
removed and regenerated at an off-site facility; or removed and disposed of.
Carbon used for metals-contaminated groundwater probably cannot be
regenerated, and should be removed and properly disposed of. The two most
common reactor configurations for carbon adsorption systems are the pulsed or
moving bed and the fixed bed. The fixed bed configuration is the most widely
used for adsorption from liquids.216
215U.S. Department of Defense, Environmental Technology Transfer Committeeflemediation Technologies Screening Matrix and Reference
Guide, Second Edition, October 1994.
216Ibid.
154
-------
PHYSICAL SEPARATION
Particulate
Filter
Influent
(Contaminated
Liquid)
Carbon Bed
>. Effluent
(Treated Water)
Spent Carbon
Exhibit 3-5: Carbon Adsorption Diagram
Source: U.S. Department of Defense, Environmental Technology Transfer Committee,Remediation
Technologies Screening Matrix and Reference Guide, Second Edition, October 1994.
Aeration injects air into the groundwater, forming bubbles that rise and carry
trapped and dissolved contaminants to the water surface.217 A diffused bubble aeration
system has successfully removed radon from drinking water. In this system, an air
blower forces air into several treatment tanks. The radon is then stripped from the
water and vented outside the treatment area.
Operating Characteristics
Through membrane processes, uranium concentrations of 300 ug/L were
reduced by 99 percent in Florida ground-water218 and initial radium concentrations of
11.6, 13.9 and 13 pCi/L were reduced to <0.1, <0.1 and 1.2 pCi/L, respectively at a
site in Illinois.219 Average flow rates during a pilot test ranged between 15-25L/min.
Costs for radium removal were estimated at $1.50 to $3.00 per gallon, but did not
include spent-media disposal costs.220 Reverse osmosis generates a concentrated waste
stream containing radionuclides that must be treated further or disposed of.
217U.S. Environmental Protection Agency,^ Citizen's Guide to Air Sparging, EPA/542/F-92/010, March 1992
218Sorg, T., "Methods for Removing Uranium from Drinking Water"/. Am. Water Works Assoc. 80(7): 105-11, July 1988.
"'Clifford, D., Vijjeswarapu W., and Subramoniuan, S., "Evaluating Various Adsorbents and Membranes for Removing Radium from
Groundwater", J. Am. Water Works Assoc. 80(7):94-104 July 1988.
155
-------
PHYSICAL SEPARATION
Removal efficiencies for microfiltration have been shown to be greater than 99
percent for uranium, plutonium, and americium with initial concentrations of 35, 30
and 30 pCi/L, respectively. Removal efficiency for gross alpha emitters was 86
percent and 43 percent for radium that had an initial concentration of 30 pCi/L.221
Treatment costs range from $.50 to $15 per 1000 gallons and depend on the volume to
be treated, treatment duration, and contaminant concentrations.222 Depending on what
is fed into the system, the micro/ultra filtration process generates three waste streams:
a filter cake of solid material, a filtrate of treated effluent, and a liquid concentrate
which contains the dissolved contaminants. The filter cake and/or liquid concentrate
require further treatment or disposal. The process time depends on the volume of
material to be treated, the contaminants present, and the concentrations of the
contaminants.
Carbon adsorption effectively removes contaminants at low concentrations
(less than 10 mg/L) from water at nearly any flow rate, and removes higher
concentrations of contaminants from water at low flow rates (2-4L/min.). Pretreatment
for the removal of solids may be required to prevent the accumulation of suspended
solids in the column. Activated carbon has been used to adsorb radon and neutral
forms of cobalt-60 and ruthenium-106. Activated carbon has also effectively reduced
groundwater uranium concentrations from 26-100 ug/L to < 1 ug/L, the carbon
capacity appeared to be limited after several months of operation.223 Treatment costs
range from $0.32 to $1.70 per 1000 liters treated, and depend on the type and
concentration of contaminants present and flow rates.224 Although activated carbon is a
well-established technology for removing organic compounds, its use in the removal
of inorganic contaminants has not been as widespread due to the low capacity and the
difficulty in regenerating spent carbon which subsequently require treatment and
disposal. Also, the presence of iron may promote fouling of the carbon.
Aeration's overall radon removal efficiency ranged from 90 percent to 99.6
percent, with initial radon concentrations in the water ranging from 1,767 pCi/L-
86,355 pCi/L.225 This suggests that radon removal efficiency improves with increased
air flow rate and/or contact time. Analysis of stack emissions during the aeration
process indicated that the off-gas would need to be diluted 104 to 105 times to be
similar to radon activities found in ambient air. If precipitation of iron and manganese
221U.S. Environmental Protection Agency,The Superfund Innovative technology Evaluation Capsule, Filter Flow Technology, Inc.,
Colloid Polishing Filter Method, EPA/540/R-94/501-a, July 1994.
222Ibid.
223Sorg, T. Methods for Removing Uranium from Drinking Water, J. Am. Water Works Assoc. 80(7): 105-11, July 1988.
224U.S. Department of Defense, Environmental Technology Transfer CommitteeRemediation Technologies Screening Matrix and
Reference Guide, Second Edition, October 1994.
225Kinner, N., Malley, J., Clement, J., Quern P. and Schell, G.Radon Removal Techniques for Small Community Public WaterSupplies.
EPA/600/S-2-90/036, November 1990.
156
-------
PHYSICAL SEPARATION
occurs during aeration operational problems may result. Raw water quality should
therefore be monitored to determine whether pretreatment is required. Treatment cost
for this technology was estimated to be $2.14 per 1000 gallon, not including treatment
of gas emissions.226
Target Contaminant Groups
Membrane processes can treat a variety of waste, including metals and
organics, and effectively removes most radionuclides from water. However, tritium
cannot be removed easily because of its chemical characteristics.227 GAC can be used
to treat organics, certain inorganics, and radionuclides such as uranium, cobalt-60, and
ruthenium-106. Aeration effectively removes volatile organics and radon.
Site Considerations
Groundwater characteristics such as contaminant type and concentration should
be well-defined in order to accurately predict system performance and costs. The
physical separation technologies can be considered where radionuclide and heavy
metal contaminants are associated with suspended solids in a liquid media, or where
precipitating agents are available for pretreating the liquid media. Extensive
pretreatment may be required to remove contaminants that will damage the membrane
or activated carbon, or will precipitate in the aeration system. All technologies require
a groundwater extraction and delivery system and adequate power to maintain the
treatment system. Also, adequate venting and/or an air treatment system are required
for aeration.
3.2.2 NCP Criteria Evaluation
Protection of Human Health and the Environment
Since these technologies remove the contaminants from the liquid media, it
eliminates the migration and exposure pathways to human and environmental
receptors, thereby protecting human and environmental health. However, site workers
may be exposed to health risks due to the potential exposure to both untreated ground-
water and the residual waste stream (e.g., filter cake, liquid concentrate or spent
carbon). If waste materials are treated off site, health risks may be associated with in
the transport and subsequent treatment and/or disposal. In addition, there is a potential
risk of exposure to radon gas emissions from the aeration process and/or disposal.
227U.S. Environmental Protection Agency,The Superfund Innovative technology Evaluation Capsule, Filter Flow Technology, Inc..
Colloid Polishing Filter Method, EPA/540/R-94/501-a, July 1994.
157
-------
PHYSICAL SEPARATION
Compliance with ARARs
The treated effluent must comply with Clean Water Act (CWA) requirements
and any local NPDES requirements prior to discharge to the environment. Air
emissions from the aeration process must comply with Clean Air Act (CAA)
requirements. Compliance with other ARARs must be determined on a site specific
basis.
Long-Term Effectiveness
Although past applications and pilot scale tests indicate consistent and
successful removal of radionuclide, heavy metal, and organic contaminants from
water, more studies are needed to assess how effectively radionuclides can be removed
from liquid media. However, since these technologies remove contaminants from
liquid media, they eliminate migration and exposure pathways. Also, the volume of
material requiring additional management (filter cake and liquid concentrate) is
usually much lower than the volume of treated media. This volume reduction also
reduces the potential for exposure to these contaminants. Ongoing monitoring and
maintenance of the treatment system is required to ensure long-term effectiveness.
Reduction of Radiotoxicity. Mobility, or Volume
These technologies effectively remove contaminants from liquid media and
concentrate them in residual filter cakes, liquid concentrates, or spent carbon; they
also reduce the mobility of these contaminants. However, the contaminants' toxicity is
not reduced by these technologies and residuals require further treatment and/or
disposal. In the aeration process, mobility of radon is greatly reduced when radon gas
emissions are captured through off-gas filtration.
Short-Term Effectiveness
For groundwater treatment, closed systems can be used to prevent any gaseous
emissions (with the exception of the aeration process). Depending on the
contaminated volume and how the groundwater is used, prevention measures such as
institutional controls may be necessary for the duration of the treatment process.
Radioactive materials in the waste stream pose a risk to onsite workers or other
receptors if the materials are transported off site for further treatment and/or disposal.
In addition, some contaminants may not be effectively removed by this process and
may remain in the treated effluent.
Implementability
158
-------
PHYSICAL SEPARATION
Previous applications and pilot tests indicate that these technologies can be
readily implemented, with limited site preparation. However, extraction and delivery
systems must be in place and adequate power must be available to maintain the
treatment system. Chemical characteristics of the contaminants must be known prior
to implementation. In many cases pretreatment may be required to ensure the
treatment's effectiveness. In addition, residual waste may require further treatment
and/or disposal. Air treatment may be required with aeration to address radon
emissions.
Cost
Costs of using these technologies are driven by the capital cost of the equipment
and the cost of utilities during operation. O&M costs decrease as the duration of
treatment increases, indicating minimal maintenance costs.228 Complications such as
contaminant fouling of the membrane or the activated carbon result in higher costs.
Pretreatment, if necessary, also will affect cost. In addition, further treatment and
disposal of the waste (e.g. filter cake, liquid concentrate, spent carbon, or gas
emissions) will raise costs.
3.2.3 Physical Separation Summary
Membrane processes, activated carbon and aeration have been applied to
ground-water contaminated with heavy metals and organic contaminants and have
been tested at the pilot scale for radionuclide-contaminated media. In general, these
technologies have effectively removed these contaminants in ground-water; however
further development is needed to assess their effectiveness with radionuclide-
contaminated liquid media. The following factors may limit the applicability of this
separation technology:
technologies do not reduce radiotoxicity;
residuals are contaminated and require further treatment and/or
disposal;
pretreatment may be required;
an air treatment system may be required with aeration to address
radon gas emissions.
159
-------
PHYSICAL SEPARATION
Exhibit 3-6 summarizes the data and analyses presented in this profile, and can
be used to compare these and any other technologies.
Exhibit 3-6: NCP Criteria for Physical Separation
NCP Criteria
Overall Protectiveness
Evaluation
Not yet fully demonstrated for
radioactive contamination
Site workers are at potential
risk from residual waste.
Other receptors are at risk if
the waste materials are
transported off site for
treatment and/or disposal.
Performance Data
Peliminary studies indicate
protectiveness is achieved.
Compliance with ARARs
CWA and CAA requirements
may apply to the residual
waste
Performance data, such as
removal efficiencies, must
be assessed in relation to
preremediation
concentrations and cleanup
standards to determine
compliance with ARARs.
Long-Term Effectiveness
and Permanence
Further development is
required to ensure
effectiveness with
radionuclide-contaminated
water.
Residual waste requires
further treatment and/or
disposal.
Pilot scale tests and studies
indicate consistent and
successful separation of
contaminants from water.
Residual waste is present in
filter cakes, liquid
concentrates, spent carbon
or gas emissions.
Reduction of
Radiotoxicity, Mobility, or
Volume
Does not reduce radioactivity
or toxicity.
Reduces mobility of
contamination through storage
or disposal of residuals
Volume occupied by the
hazardous or radioactive
component is reduced
Contaminants are
concentrated in residual
filter cakes and/or liquid
concentrates or spent
carbon, reducing the
volume and mobility of the
contaminants. In the case
of aeration, the mobility of
the contaminants is
reduced when captured in
off-gas filtration system.
160
-------
PHYSICAL SEPARATION
Exhibit 3-6: NCP Criteria for Physical Separation (Cont.)
NCP Criteria
Short-Term Effectiveness
Evaluation
Potential risk to onsite workers
from residual waste.
Performance Data
Residual waste requires
further treatment and/or
disposal.
Implementability
Variations of these technologies
have been successfully tested at
the pilot scale.
A groundwater extraction and
delivery system and adequate
power are needed to maintain
the treatment system.
Numerous treatment
systems are being tested for
addressing radionuclide-
contaminated liquid media.
Cost
Capital and O&M costs vary
for these technologies and
depend on the type of treatment
system and volume of
groundwater to be treated.
O&M costs decrease as the
duration of treatment
increases.
Waste disposal and
pretreatment increase costs.
161
-------
Appendix A
RADIOACTIVE CONTAMINATION:
BASIC CONCEPTS & TERMS
-------
-------
RADIOACTIVE CONTAMINATION:
BASIC CONCEPTS & TERMS
Types of Radioactive Waste
Although there are hundreds of known radioactive isotopes, only a small fraction of
these are likely to be seen at contaminated sites. This effect is due to the fact that many
isotopes are nearly impossible to create without exotic scientific equipment and many others
have extremely short half-lives and therefore do not exist long enough to make it outside the
facility where they were created. Among the radioactive isotopes likely to be encountered in
disposal and remediation sites are naturally occurring radioactive material (NORM) such as
uranium-238, thorium-232, thorium-230, radium-226, and radon -222; radioactive fission
products such as cesium-137 and strontium-90; and products of neutron bombardment such as
cobalt-60. The radioactive isotopes in place at one particular site will depend on the source of
the material spilled or disposed there.
Radioactive isotopes originate from both manufactured and natural sources. Nuclear
reactors and particle accelerators, for example, can generate radioactive isotopes by forcefully
de-stabilizing their nuclei in a process known as fissioning (splitting of the atom). Fissioning
can split larger atoms, such as uranium or plutonium, into multiple, smaller, radioactive
elements. Reactors also can create radioactive isotopes from stable elements by causing
additional neutrons to be absorbed into their nuclei, which may result in an unstable (energy-
emitting) configuration. This is called neutron activation. Additionally, particle accelerators,
cyclotrons, and similar machines can create radioactive isotopes from stable elements by
bombarding their nucleus with a variety of particles. This process is often used to create
medical isotopes.
The development and use of radioactive materials inevitably results in the production
of radioactive waste. The treatment and disposal of the potentially harmful waste is a matter
of much concern and controversy. Again, the management of this waste had led to the
development of definitions and authorities to assign responsibility for their handling. Exhibit
A-l is a summary of categories and definitions, and the authority from which it is cited. The
technologies presented in this Guide are most likely to be applicable to low-level,
NARM/NORM, and mixed wastes.
A-l
-------
Exhibit A-l: Statutory and Regulatory Categories of Radioactive Waste
Category of
Radioactive Waste
High-Level Waste
(HLW)
Low-Level Waste
(LLW)
Class A, B, C, and
Greater-Than-Class-
C (GTCC) Wastes
Transuranic Waste
(TRU Waste)
AEA Waste
NARM/NORM
Wastes
Mixed Waste
Definition
Irradiated reactor fuel; liquid waste resulting from
the operation of the first-cycle solvent extraction
system, or equivalent, and the concentrated waste
from subsequent extraction cycles, or equivalent, in a
facility reprocessing irradiated reactor fuel; and
solids into which such liquid waste has been
converted.
Radioactive waste not classified as high-level waste,
transuranic waste, spent fuel, or byproduct materials
such as uranium and thorium mill tailings.
LLW categorized according to its radionuclide
concentration and half-life. In general, Class A waste
has the lowest concentrations of particular
radionuclides. Class B and C wastes contain
radionuclides in higher concentrations. GCC waste
exceeds the concentration limits established for
Class C waste.
Waste containing elements with atomic numbers
greater than 92 and half-lives greater than 20 years,
in concentrations greater than 100 nCi/g of alpha-
emitting isotopes.
Waste containing or contaminated with source,
byproduct, or special nuclear material.
Waste containing or contaminated with any
radioactive material produced as a result of nuclear
transformations in an accelerator, and any nuclide
that is radioactive in its natural physical state (i.e.,
not anthropogenic), excluding source and special
nuclear material.
Hazardous waste as defined by RCRA containing or
contaminated with source, byproduct, or special
nuclear material.
Citation
Nuclear Waste Policy Act
[10CFR60]
Low-Level Radioactive
Waste Policy Act
[10CFR61]
10CFR61
40CFR191
Atomic Energy Act
State authority
Federal Facilities
Compliance Act of 1992
A-2
-------
Nature of Radioactivity
Nearly all elements (e.g., oxygen, carbon) in nature can be found in a variety of
nuclear compositions. Isotopes, which are different forms of an element, have the same
atomic number, but different atomic mass. That is, their nuclei have the same number of
protons but different numbers of neutrons. Carbon, for example, contains six protons in its
nucleus but may have either six (carbon-12), seven (carbon-13), or eight (carbon-14)
neutrons.
Isotopes that are unstable will undergo radioactive decay in order to reach a more
stable nuclear configuration. These unstable isotopes are called radioactive isotopes.
Radioactive isotopes spontaneously emit energy and particles in the form of alpha (positively
charged) or beta (negatively charged) particles, and/or gamma rays (which are similar to X
rays in behavior) as part of the radioactive decay process. This emitted or expended
energyradiationand its spontaneous activity (radioactivity) form its potentially creative or
destructive power. Carbon-14, for example, is a radioactive isotope that will decay by
emitting a beta particle and form nitrogen-14.
An alpha particle is a positively charged particle, emitted from the nucleus of a
decaying radioactive atom (alpha emitters), containing two neutrons and two protons identical
to the nucleus of a helium atom. Because alpha particles are "massive" on an atomic scale,
they can be easily shielded and are stopped by a sheet of paper. Thus, they do not penetrate
human skin, but they can be dangerous when the alpha emitting atom is inhaled, or if the atom
enters the body through a cut, food, or water, and permitted to decay inside the body. The
exposure to alpha particles usually occurs through internal pathways (ingestion and
inhalation).
A beta particle is essentially an electron emitted from the nucleus of a decaying atom.
Beta particles are less massive than alpha particles but are also relatively easy to shield. Some
beta particles can penetrate skin. As with alpha emitters, beta emitters cause the most damage
when the atom is ingested and allowed to decay inside the body. The exposure to beta
particles usually occurs mainly through internal pathways and some may occur through
external pathways.
Gamma rays are similar to x rays (although they are produced differently); however,
gamma rays are of higher energy and thus have stronger penetrating power. Gamma rays can
penetrate and damage critical organs in the body and are the most difficult of the radiation
types to shield. The exposure to gamma rays is usually of concern through external pathways
but it can also occur through internal pathways.
Included among the naturally occurring radioactive elements are uranium-238, carbon-
14, hydrogen-3 (tritium), thorium-230, radium-226, radon-222, and potassium-40. In
addition, radioactive elements can be created as products of the decay of other radioactive
A-3
-------
isotopes. When the nucleus of uranium-23 8 decays, for example, it produces thorium-234
(radioactive) which, in turn, decays to become protactinium-234. This process of decay
continues until a stable element is reached. Sequences such as these are called decay chains.
The radioactive decay is usually a first order reaction where disintegration of radionuclide is
proportional to the activity present. Exhibit A-2 presents the radioactive decay process for the
uranium (U) series. Uranium-238 decays to a final stable atom of lead (Pb206). The half-life
and decay energy for each of the newly formed decay products is shown in Exhibit A-3.
IP8
4.5X109y
4.2 MeV
\
f
Th234 '
24 d
0.2,0.
1 MeV
Pa234m '
1.2 min
2.3 MeV
u
F,
2.5X10"y
4.7-4.8 MeV
^
Th230
8.0X104y
4.6-4.7 MeV
Ptf218
3.05 min
6.0
MeV
Pb214 "
26.8 min
07,1.0 MeV
Bi214 '
19.7 min
0.4-3.3 Me\
f
Po
1.6X
1 77
Pb
214
10 S
MeV
210 /
21 y
<0.1
MeV
Bi210 '
5.0 d
1 .2 MeV
f
Po210
138 d
f 5.3 MeV
T
Pb206
Stable
Exhibit A-2: Principal Decay Scheme of the Uranium Series
Each radioactive isotope has a specific rate of decay, known as its half-life, which is
the time required for the isotope to decay to half of its original quantity. Carbon-14 has a
half-life of 5,730 years, meaning that in that time, one gram of carbon-14 will become one-
half gram of C-14 (the other one-half gram would have decayed to nitrogen-14 through beta
A-4
-------
decay of carbon-14 atoms). In an additional 5,730 years, the amount will be reduced to 0.25
grams of carbon-14 (with 0.75 grams having been transformed to nitrogen-14). Half-lives are
unique to each radioactive isotope. Exhibit A-3 presents the half-lives and average radiation
energies for alpha, beta and gamma radiation for some of the radionuclides found at
Superfund sites.
Exhibit A-3: Radiological Characteristics of Selected Radionuclides Found at Superfund
Sites3
Radio-
Nuclide
Am-241
Am-243
C-14
Cs-134
Cs-135
Cs-137
H-3
K-40
Pu-238
Pu-239
Pu-240
Pu-241
Pu-242
Ra-226
Ra-228
Th-230
Th-232
U-234
U-235
U-238
Average Radiation Energies (MeV/decay) b
Half-life0
4.32xl02y
7.38xl03y
5.73xl03y
2.06x10° y
2.30xl06y
3.00x10' y
1.23x10' y
1.28xl09y
8.77x10' y
2.41xl04y
6.54xl03y
1.44x10' y
3.76xl05y
1.60xl03y
5.75x10° y
7.70xl04y
1.41xlO'°y
2.44xl05y
7.04xl08y
4.47xl09y
Alpha
5.57x10°
5.36x10°
--
--
--
--
5.59x10°
5.24x10°
5.24x10°
1.22xl04
4.97x10°
4.86x10°
4.75x10°
4.07x10°
4.84x10°
4.47x10°
4.26x10°
Beta
5.21xlO-2
2.17xlQ-2
4.95xlO-2
1.64x10-'
6.73xlO-2
1.87x10-'
5.68xlO-3
5.23x10-'
1.06xlO-2
6.74xlO'3
1.06xlO-2
5.25xlQ-3
8.73xlO-3
3.59xlQ-3
1.69xlO-2
1.42xlQ-2
1.25xlO-2
1.32xlQ-2
4.92xlO-2
LOOxlO'2
Gamma
3.24xlO-2
5.61xlQ-2
1.55x10°
--
--
1.56x10-'
l.SlxlO'3
8.07xlQ-4
1.73xlO-3
2.55xlQ-6
1.44xlQ-3
6.75xlQ-3
4.14xlO-9
l.SSxlO'3
1.33xlO-3
1.73xlQ-3
1.56x10-'
1.36xlQ-3
jJSourcelCRP 1983.
Computed as the sum of the products of the energies and yields of individual radiations.
Half-life expressed in years (y).
A-5
-------
Basic Terms, Types and Units of Radiation
Basic Terms
Activity
The number of nuclear transitions occurring in a given quantity of radioactive material per
unit time.
Background Radiation
The radiation in man's natural environment, including cosmic rays and radiation (which may
vary from location) from the naturally radioactive elements, both outside and inside the
bodies of humans and animals. It is also called natural radiation.
Decay Constant
The fraction of the amount of a radionuclide that undergoes transition per unit time.
Dose
A general term denoting the quantity of radiation or energy absorbed. For special purposes it
must be appropriately qualified. If unqualified, it refers to absorbed dose.
Ion
Atomic particle, atom, or chemical radical bearing an electric charge, either negative or
positive.
lonization
The process of adding one or more electrons to, or removing one or more electrons from,
atoms or molecules, thereby creating ions. High temperatures, electrical discharges, or
nuclear radiations can cause ionization.
Ionizing radiation
Ionizing radiation is radiation with enough energy so that during an interaction with an atom,
it can remove tightly bound electrons from their orbits, causing the atom to become charged
or ionized. Examples are gamma rays and neutrons.
A-6
-------
A-7
-------
Isotope
One of several nuclides having the same number of protons in their nuclei, and hence having
the same atomic number, but differing in the number of neutrons, and therefore, in the mass
number. Almost identical chemical properties exist between isotopes of a particular element.
The use of this term as a synonym for nuclide is to be discouraged.
Non-ionizing radiation
Nonionizing radiation is radiation without enough energy to remove tightly bound electrons
from their orbits around atoms. Examples are microwaves and visible light.
Radiation
Radiation is energy in transit in the form of high speed particles and electromagnetic waves.
We encounter electromagnetic waves every day. They make up our visible light, radio and
television waves, ultra violet (UV), and microwaves with a spectrum of energies. These
examples of electromagnetic waves do not cause ionizations of atoms because they do not
carry enough energy to separate molecules or remove electrons from atoms.
Radioactive Decay
The process by which a spontaneous change in nuclear state takes place. This process is
accompanied by the emission of energy in various specific combinations of electromagnetic
and corpuscular radiation and neutrinos.
Radioactivity
Radioactivity is the spontaneous transformation of an unstable atom and results in the
emission of energy. This process is referred to as a transformation, a decay or a
disintegrations of an atom.
Radiotoxicity
Potential of an isotope or mass of radioactive material to cause adverse health effects to living
tissue by absorption of energy from the decay of the radioactive material.
A-8
-------
Common Units of Radiation
Becquerel (Bq)
The Becquerel is a unit used to measure a radioactivity. One Becquerel is that quantity of
radioactive material that will have 1 transformations in 1 second. Often radioactivity is
expressed in larger units like: thousands (kBq), millions (MBq) or even billions (GBq) of
becquerels. As a result of having 1 Becquerel being equal to one transformation per second,
there are 3.7 X 1010 Bq in 1 curie.
Curie (Ci)
The curie is a unit used to measure a radioactivity. One curie is that quantity of a radioactive
material that will have 37,000,000,000 transformations in 1 second. Often radioactivity is
expressed in smaller units like: thousandths (mCi), millionths (uCi) or even billionths (nCi)
of a curie. The relationship between becquerels and curies is: 3.7 X 1010 Bq in 1 curie.
Rad (radiation absorbed dose)
The rad is a unit used to measure a quantity called absorbed dose. This relates to the amount
of energy actually absorbed in some material and is used for any type of radiation and any
material. One rad is defined as the absorption of 100 ergs per gram of material. The unit rad
can be used for any type of radiation, but it does not describe the biological effects of the
different radiations.
Rem (roentgen equivalent man)
The rem is a unit used to derive a quantity called equivalent dose. This relates the absorbed
dose in human tissue to the effective biological damage of the radiation. Not all radiation has
the same biological effect, even for the same amount of absorbed dose. Equivalent dose is
often expressed in terms of thousandths of a rem, or mrem. To determine equivalent dose
(rem), you multiply absorbed dose (rad) by a quality factor (Q) that is unique to the type of
incident radiation.
Roentgen
The roentgen is a unit used to measure a quantity called exposure. This can only be used to
describe an amount of gamma and X rays, and only in air. One roentgen is equal to
depositing 2.58 E-4 coulombs per kg of dry air. It is a measure of the ionizations of the
molecules in a mass of air. The main advantage of this unit is that it is easy to measure
directly, but it is limited because it is only for deposition in air, and only for gamma and x
rays.
A-9
-------
A-10
-------
Appendix B
BIBILOGRAPHY
-------
BIBILOGRAPHY
GENERAL READING
International Atomic Energy Agency, Proceedings of An International Symposium on
Geologic Disposal of Spent Fuel, High Level and Alpha Bearing Wastes., October 1992.
International Atomic Energy Agency, Proceedings of an International Symposium on the
Conditioning of Radioactive Wastes for Storage and Disposal, June 1982.
International Atomic Energy Agency, Radioactive Waste Management Glossary, December
1993.
International Atomic Energy Agency, Report on Radioactive Waste Disposal, Technical
Report Series n349, January 1993.
International Atomic Energy Agency, Safety Series, "Classification of Radioactive Waste,"
nlll-G-l.l,May 1984.
International Atomic Energy Agency, Safety Series, "Control of Radioactive Waste Disposal
into the Marine Environment," n61, September 1983.
International Atomic Energy Agency, Safety Series, "Criteria for Underground Disposal of
Solid Radioactive Wastes," n60, 1983.
International Atomic Energy Agency, Safety Series, "Design and Operation of Radioactive
Waste Incineration Facilities," n!08, September 1992.
International Atomic Energy Agency, Status of Technology for Volume Reduction and
Treatment of Low and Intermediate Level Solid Radioactive Waste, Technical Reports
Series n360, April 1994.
Oak Ridge National Laboratory, ORNL/M-2751/V1, AND /V2 Part B, Oak Ridge Remedial
Action Technology Logic Diagram, 1993.
Oak Ridge National Laboratory, Review, "Strategies for Radwaste Management," vol 26 no
2., 1993, p26.
Rumer, R. and Mitchell, J., Assessment of Barrier Containment Technologies -A
Comprehensive Treatment for Environmental Remediation Applications, August 1995.
Thermal Process Evaluation for RWMC Wastes, EGG-WTD-9449, January 1991.
U.S. Department of Defense, Defense Environmental Restoration Program, Annual Report to
Congress for Fiscal Year 1992, April 1993.
U.S. Department of Energy, DE910295XSP, In-Situ Vitrification of Buried Waste Sites, 1992.
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U.S. Department of Energy, DE92013873, Mixed Waste Technology: Research,
Development, Demonstration, Testing, and Evaluation, 1992.
U.S. Department of Energy, DE92018012, An Overview ofln-Situ Waste Treatment
Technologies, 1992.
U.S. Department of Energy, DE93011397, Mixed Waste Integrated Program Interim
Evaluation Report on Thermal Treatment Technologies, February 1993.
U.S. Department of Energy, DOE/EM-0121P, Office of Environmental Management, Office
of Technology Development, Supercritical Water Oxidation Program, February 1994.
U.S. Department of Energy, DOE/EM-0123P, Office of Environmental Management, Office
of Technology Development, Rocky Flats Compliance Program, February 1994.
U.S. Department of Energy, DOE/EM-0124P, Office of Environmental Management, Office
of Technology Development, Minimum Additive Waste Stabilization (MAWS), February
1994.
U.S. Department of Energy, Office of Environmental Management, Office of Technology
Development, In-Situ Remediation Integrated Program, DOE/EM-0134P, February 1994.
U.S. Department of Energy, Office of Environmental Management, Office of Technology
Development, Technology Catalogue, DOE/EM-0138P, February 1994.
U.S. Department of Energy, Office of Environmental Management, Office of Technology
Development, Uranium in Soils , DOE/EM-0148P, March 1994.
U.S. Department of Energy, Office of Environmental Management, Office of Technology
Development, Buried Waste Integrated Demonstration, DOE/EM-0149P, March 1994.
U.S. Environmental Protection Agency, Technological Approaches to the Cleanup of
Radiologically ContaminatedSuperfundSites, EPA/540/2-88/002, August 1988.
U.S. Environmental Protection Agency, Assessment of Technologies for the Remediation of
Radioactively Contaminated Superfund Sites, EPA/540/2-90/001, January 1990.
U.S. Environmental Protection Agency, The Superfund Innovative Technology Evaluation
Program: Technology Profiles, EPA/540/R-92/077, 6th Edition, 1992.
U.S. Environmental Protection Agency, The Superfund Innovative Technology Evaluation
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U.S. Environmental Protection Agency, Approaches for the Remediation of Federal Facility
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1993.
Waste Landfill Integrated Demonstration., February 1994
CONTAINMENT TECHNOLOGIES
CAPPING
Frobel, R. "Geomembranes in Surface Barriers" Environmental Restoration Conference,
1995.
U.S. Environmental Protection Agency, Office of Research and Development, Technological
Approaches to the Cleanup of Radiologically Contaminated Superfund Sites, EPA/540/2-
88/002, August 1988.
Oak Ridge National Laboratory, Natural, Physical, and Biological Processes Compromise the
Long-term Performance of Compacted Soil Caps. Environmental Restoration Conference,
1995.
Oak Ridge National Laboratory, Oak Ridge National Laboratory Technology Logic
Diagrams, Volume 2, Part B, Remedial Action, ORNL/M-2751/V2/Pt.B, September 1993.
U.S. Department of Defense, Environmental Technology Transfer Committee, Remediation
Technologies Screening Matrix and Reference Guide, Second Edition, October 1994.
U.S. Department of Energy, "Decision Support System, " Technology Catalog, 1994.
U.S. Environmental Protection Agency. Background Information Document for Radiation
Site Cleanup Proposed Rule, Revised Draft, August 1995.
LAND ENCAPSULATION
Argonne National Laboratory. "Encapsulation of Hazardous Ions in Smectite Clays" project
description - 1994.
Oak Ridge National Laboratory and Idaho National Engineering Laboratory Technology
Catalog Site Remediation Profiles: Remote Excavation System - 1993.
Terran Environmental Inc. "In-situ Encapsulation of Buried Waste" Project Description,
1994.
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U.S. Environmental Protection Agency, Office of Research and Development, Technological
Approaches to the Cleanup of Radiologically Contaminated Superfund Sites, EPA/540/2-
88/002, August 1988.
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response,
Assessment of Technologies for the Remediation ofRadioactive ly Contaminated
Superfund Sites, EPA/540/2-90/001, January 1990.
CRYOGENIC BARRIERS
Cryocell, Responses to Commonly Asked Questions About Frozen Soil Barriers Containing
Hazardous Waste.
Fremond, M., Ground Freezing 94, from the Proceedings of the Seventh International
Symposium on Ground Freezing, Nancy, France, October 24-28, 1994.
Oak Ridge National Laboratory, Oak Ridge National Laboratory Technology Logic
Diagrams, Volume 2, Part B, Remedial Action, ORNL/M-2751/V2/Pt.B, September 1993.
Oak Ridge National Laboratory, Oak Ridge National Laboratory Technology Logic
Diagrams, Volume 3, Part B, Remedial Action, ORNL/M-2751/V3/Pt.B, September 1993.
RKK, Ltd. Vendor Information.
U.S. Environmental Protection Agency, Office of Research and Development, Superfund
Innovative Technology Evaluation Program: Technology Profiles, Seventh Edition,
EPA/540/R-94/526, November 1994.
U.S. Department of Energy, Frozen Soil Barrier Technology, Innovative Technology
Summary Report, DOE/EM-0273, April 1995.
VERTICAL BARRIERS
Heiser, J. "Demonstration of Close-Coupled Barriers for Sub-Surface Containment of Buried
Waste." Environmental Restoration Conference, 1995.
Mauro, M. "Construction of Deep Barrier Walls for Waste Containment." Environmental
Restoration Conference, 1995.
MWLID Sandia/Westinghouse Hanford, "Verification of Sub-Surface Barriers using Time
Domain Reflectometry (TDR) with Waveguides," 1994.
Oak Ridge National Laboratory, Oak Ridge National Laboratory Technology Logic
Diagrams, Volume 3, Technology Evaluation Data Sheets, Part B, Dismantlement -
Remedial Action, ORNL/M-2751/V3/Pt.B, September 1993.
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Siskind, B. and Heiser, J. "Regulatory Issues and Assumptions Associated with Barriers in
the Vadose Zone Surrounding Buried Waste." Brookhaven National Laboratory, 1993.
U.S. Department of Defense, Environmental Technology Transfer Committee, Remediation
Technologies Screening Matrix and Reference Guide., Second Edition, October 1994.
U.S. Environmental Protection Agency, Office of Research and Development, Technological
Approaches to the Cleanup of Radiologically Contaminated Superfund Sites, EPA/540/2-
88/002, August 1988.
SOLIDIFICATION/STABILIZATION TECHNOLOGIES
CEMENT SOLIDIFICATION/STABILIZATION (S/S)
Oak Ridge National Laboratory, Oak Ridge National Laboratory Technology Logic
Diagrams, Volume 3, Part B, Remedial Action, ORNL/M-2751/V3/Pt.B, September 1993.
PNL-SA-21482 October 1992.
U.S. Department of Defense, Environmental Technology Transfer Committee, Remediation
Technologies Screening Matrix and Reference Guide, Second Edition, October 1994.
U.S. Environmental Protection Agency, Office of Emergency and Remedial Response,
Summary of Treatment Technology Effectiveness for Contaminated Soil, PB92-963351,
June 1990.
U.S. Environmental Protection Agency, Office of Emergency and Remedial Response,
Solification/Stabilization ofOrganics and Inorganics, EPA/540/S-92/015, May 1993.
U.S. Environmental Protection Agency, Office of Air and Radiation,
Stabilization/Solidification Processes for MixedWaste, EPA 402-R-96-014, June 1996.
U.S. Environmental Protection Agency, Office of Research and Development, Approaches for
the Remediation of Federal Facility Sites Contaminated with Explosive or Radioactive
Wastes, EPA/625/R-93/013, September 1993.
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response,
Assessment of Technologies for the Remediation ofRadioactive ly Contaminated
Superfund Sites, EPA/540/2-90/001, January 1990.
CHEMICAL SOLIDIFICATION/STABILIZATION
U.S. Department of Defense, Environmental Technology Transfer Committee, Remediation
Technologies Screening Matrix and Reference Guide, Second Edition, October 1994.
U.S. Environmental Protection Agency, EPA/540/M5/89/001, 1989.
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U. S. Environmental Protection Agency, Office of Research and Development, Approaches
for the Remediation of Federal Facility Sites Contaminated with Explosive or Radioactive
Wastes, EPA/625/R-93/013, September 1993.
CHEMICAL SEPARATION TECHNOLOGIES
SOLVENT/CHEMICAL EXTRACTIONS
Oak Ridge National Laboratory, Technology Evaluation Data Sheets, Part B, Dismantlement -
Remedial Action, ORNL/M-2751/V3/Pt.B, September 1993.
U.S. Department of Defense, Environmental Technology Transfer Committee, Remediation
Technologies Screening Matrix and Reference Guide, Second Edition, October 1994.
U.S. Department of Energy, Office of Technology Development, Effective Separation and
Processing Integrated Program (ESP-IP), DOE, EM-0126P, 1994.
U.S. Environmental Protection Agency and U.S. Department of Defense, Remediation
Technology Screening Matrix and Reference Guide/Version 1, 1993.
U.S. Environmental Protection Agency, Emerging Technology Summary: Acid Extraction
Treatment System for Treatment of Metal Contaminated Soils, EPA/540/SR-94/513,
August 1994.
U.S. Environmental Protection Agency, Office of Research and Development, Technological
Approaches to the Cleanup of Radiologically Contaminated Superfund Sites, EPA/540/2-
88/002, August 1988.
U.S. Environmental Protection Agency. Background Information Document for Radiation
Site Cleanup Proposed Rule, Revised Draft, August 1995.
ION EXCHANGE & CHEMICAL PRECIPITATION
Oak Ridge National Laboratory, Technology Evaluation Data Sheets, Part B, Dismantlement -
Remedial Action, ORNL/M-2751/V3/Pt.B, September 1993.
Sorg, Thomas J., "Methods for Removing Uranium From Drinking Water," July 1988.
U.S. Department of Energy, Office of Environmental Restoration, Decommissioning
Handbook, DOE, EM-0142P, March 1994.
U.S. Environmental Protection Agency, EPA/625/R-93/013, Approaches for the Remediation
of Federal Facility Sites Contaminated with Explosive or Radioactive Waste, 1993.
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U.S. Department of Defense, Environmental Technology Transfer Committee, Remediation
Technologies Screening Matrix and Reference Guide, Second Edition, October 1994.
PHYSICAL SEPARATION TECHNOLOGIES
DRY SOIL SEPARATION
Thermo Nutech, Environmental Field Services Group, Statement of Qualifications and
Description of Thermo Nutech's Segmented Gate System, Oakridge, TN, 1996.
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Sites Contaminated with Explosive or Radioactive Wastes, EPA/625/R-93/013, September
1993.
U.S. Environmental Protection Agency, SuperfundInnovative Technology Evaluation
Program, Technology Profiles Seventh Edition, EPA/540/R-94/526, November 1994.
MEMBRANE FILTRATION, CARBON ADSORPTION, AND AERATION
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Membranes for Removing Radium from Groundwater, J. Am. Water Works Assoc.
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Kinner, N., Malley, J., Clement, J., Quern P. and Schell, G. Radon Removal Techniques for
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80(7): 105-11, July 1988.
U.S. Department of Defense, Environmental Technology Transfer Committee, Remediation
Technologies Screening Matrix and Reference Guide, Second Edition, October 1994.
U.S. Environmental Protection Agency, A Citizen's Guide to Air Sparging, EPA/542/F-
92/010, March 1992.
U.S. Environmental Protection Agency, The Superfund Innovative technology Evaluation
Capsule; Filter Flow Technology, Inc., Colloid Polishing Filter Method, EPA/540/R-
94/501-a, July 1994.
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SOIL WASHING
Argonne National Laboratory, Soil Washing as a Potential Remediation Technology for
Contaminated DOE Sites, DE93-009205, March 1993.
U.S. Department of Energy, Results of a Soil Washing Demonstration Project for Low-Level
Radioactively Contaminated Soil, DOE/OR/21949-404, June 1996.
U.S. Environmental Protection Agency, Federal Remediation Technologies Roundtable,
Synopses of Federal Demonstrations of Innovative Site Remediation Technologies, EPA/
542/B-92/003, August 1992.
U.S. Environmental Protection Agency, Innovative Site Remediation Technology, Soil
Washing/Soil Flushing, Volume 3, EPA 542-B-93-012, November 1993.
U.S. Environmental Protection Agency, Technological Approaches to the Cleanup of
Radiologically ContaminatedSuperfundSites, EPA/540/2-88/002, August 1988.
FLOTATION
Organization for Economic Cooperation and Development, Uranium Extraction Technology,
OECD, Paris 1983.
Raicevic, D., Decontamination of Elliot Lake Uranium Tailing, CIM Bulletin, 1970.
U.S. Department of Energy, Heavy Metals Contaminated Soil Project, Resource Recovery
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0129P, February 1994.
U.S. Environmental Protection Agency, Technological Approaches to the Cleanup of
Radiologically Contaminated Superfund Sites, EPA/540/2-88/002, August 1988.
VITRIFICATION TECHNOLOGIES
IN-SITU VITRIFICATION
Oak Ridge National Laboratory, Technology Evaluation Data Sheets, Part B, Dismantlement
Remedial Action, ORNL/M-2751/V3/Pt.B, September 1993.
Shade, J.W., Thompson, L.E., and Kindle, C.H., In-Situ Vitrification of Buried Waste Sites
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Tixier, J.S. and Thompson, B.E., In-Situ Vitrification: Providing A Comprehensive Solution
for Remediation of Contaminated Soils, in Proceedings of the 1993 International
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Ahlstroem, P.-E., et.al., Prague, Czech Republic, 1993.
U.S. Department of Defense, Environmental Technology Transfer Committee, Remediation
Technologies Screening Matrix and Reference Guide., Second Edition, October 1994.
U.S. Environmental Protection Agency, Approaches for the Remediation of Federal Facility
Sites Contaminated with Explosive or Radioactive Wastes, EPA/625/R-93/013, September
1993.
U.S. Environmental Protection Agency, EPA, 540/MR-94/520, 1994.
U.S. Environmental Protection Agency, Vitrification Technologies for Treatment of
Hazardous and Radioactive Waste, EPA/625/R-92/002, May 1992.
EX-SITU VITRIFICATION
Hoffeiner, W., Chrubasik, A., Eschenbach, R.C., Volume Reduction and Vitrification of
Nuclear Waste with Thermal Plasma, Proceeds of the 1993 International Conference on
Nuclear Waste Management and Environmental Remediation, Volume 3, 1993.
Oak Ridge National Laboratory, Oak Ridge National Laboratory Technology Logic
Diagrams, Volume 2, Part B, Remedial Action, ORNL/M-2751/V2/Pt.B, September 1993.
U.S. Department of Defense, Environmental Technology Transfer Committee, Remediation
Technologies Screening Matrix and Reference Guide, Second Edition, October 1994.
U.S. Department of Energy, Office of Environmental Management, Office of Technology
Development, Buried Waste Integrated Demonstration, DOE/EM-0149P, March 1994.
U.S. Department of Energy, Office of Environmental Management, Office of Technology
Development, Minimum Additive Waste Stabilization, Technology Summary, DOE/EM -
0124P, February 1994.
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U.S. Department of Energy, Office of Environmental Management, Office of Technology
Development, Technology Catalogue, First Edition, DOE/EM-0138P, February 1994.
U.S. Environmental Protection Agency, SuperfundInnovative Technology Evaluation
Program: Technology Profiles, Seventh Edition , EPA/540/R-94/526, November 1994.
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