oEPA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
EPA-600/7-80-012e
March 1980
Waste and Water
Management for
Conventional Coal
Combustion: Assessment
Report - 1979
Volume V.
Disposal of FGC Wastes
Interagency
Energy/Environment
R&D Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports m this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide'range of energy-related environ-
mental issues.
EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for publication. Approval does not signify that the contents necessarily reflect
the views and policies of the Government, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/7-80-012e
March 1980
Waste and Water Management
for Conventional Coal Combustion
Assessment Report - 1979
Volume V. Disposal of FGC Wastes
by
CJ. Santhanam, R.R. Lunt, C.B. Cooper,
D.E. Klimschmidt, I. Bodek, and W.A. Tucker (ADL);
and C.R. Ullrich (University of Louisville)
Arthur D. Little, Inc.
20 Acorn Park
Cambridge, Massachusetts 02140
Contract No. 68-02-2654
Program Element No. EHE624A
EPA Project Officer: Julian W. Jones
Industrial Environmental Research Laboratory
Office of Environmental Engineering and Technology
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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PARTICIPANTS IN THIS STUDY
This First Annual R&D Report is submitted by Arthur D. Little, Inc.
to the U. S. Environmental Protection Agency (EPA) under Contract No.
68-02-2654. The Report reflects the work of many members of the
Arthur D. Little staff, subcontractors and consultants. Those partici-
pating in the study are listed below.
Principal Investigators
Chakra J. Santhanam
Richard R. Lunt
Charles B. Cooper
David E. Kleinschmidt
Itamar Bodek
William A. Tucker
Contributing Staff
Armand A. Balasco Warren J. Lyman
James D. Birkett Shashank S. Nadgauda
Sara E. Bysshe James E. Oberholtzer
Diane E. Gilbert James I. Stevens
Sandra L. Johnson James R. Valentine
Subcontractors
D. Joseph Hagerty University of Louisville
C. Robert Ullrich University of Louisville
We would like to note the helpful views offered by and discussions
with Michael Osborne of EPA-IERL in Research Triangle Park, N. C. , and
John Lum of EPA-Effluent Guidelines Division in Washington, D. C.
Above all, we thank Julian W. Jones, the EPA Project Officer, for
his guidance throughout the course of this work and in the preparation
of this report.
ii
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ACKNOWLEDGEMENTS
Many other individuals and organizations helped by discussions with
the principal investigators. In particular, grateful appreciation is
expressed to:
Aerospace Corporation - Paul Leo, Jero*ne Rossoff
Auburn University - Ray Tarrer and others
Department of Energy - Val E. Weaver
Dravo Corporation - Carl Gilbert, Carl Labovitz, Earl Rothfuss
and others
Electric Power Research Institute (EPRI) - John Maulbetsch,
Thomas Moraski and Dean Golden
Environmental Protection Agency, Municipal Environmental Research
Laboratory - Robert Landreth, Michael Roulier, and Don Banning
Federal Highway Authority - W. Clayton Onnsby
IU Conversion Systems (IUCS) - Ron Bacskai, Hugh Mullen
Beverly Roberts, and others
Louisville Gas and Electric Company - Robert P. Van Ness
National Ash Association - John Faber
National Bureau of Standards - Paul Brown
Southern Services - Reed Edwards, Lament Larrimore, and Randall Rush
Tennessee Valley Authority (TVA) - James Crowe, T-Y. J. Chu,
H. William Elder, Hollis B. Flora, R. James Ruane,
Steven K. Seale, and others
iii
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CONVERSION FACTORS
English/American Units
Length:
1 inch
1 foot
1 fathom
1 mile (statute) :
1 mile (nautical)
Area:
1 square foot
1 acre
Volume:
1 cubic foot
1 cubic yard
1 gallon
1 barrel (42 gals)
Weight/Mass:
1 pound
1 ton (short)
Pressure:
1 atmosphere (Normal)
1 pound per square inch
1 pound per square inch
Concentration:
1 part per million (weight)
Speed:
1 knot
Energy/Power:
1 British Thermal Unit
1 megawatt
1 kilowatt hour
Temperature:
1 degree Fahrenheit
Metric Equivalent
2.540 centimeters
•
0.3048 meters
1.829 meters
1.609 kilometers
1.852 kilometers
0.0929 square meters
4,047 square meters
28.316 liters
0.7641 cubic meters
3.785 liters
0.1589 cu. meters
0.4536 kilograms
0.9072 metric tons
101,325 pascal
0.07031 kilograms per square centimeter
6894 pascal
1 milligram per liter
1.853 kilometers per hour
1,054.8 joules
3.600 x 109 joules per hour
3.60 x 106 joules
5/9 degree Centigrade
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GLOSSARY
Cement!tious: A chemically precipitated binding of particles
resulting in the formation of a solid mass.
Fixation: The process of putting into a stable or unalterable
form.
Impoundment: Reservoir, pond, or area used to retain, confine,
or accumulate a fluid material.
Leachate: Soluble constituents removed from a substance by the
action of a percolating liquid.
Leaching Agent; A material used to percolate through something
that results in the leaching of soluble constituents.
Pozzolan; A siliceous or aluminosiliceous material that in
itself possess little or no cementitious value but that in
finely divided form and in the presence of moisture will react
with alkali or alkaline earth hydroxide to form compounds possessing
cementitious properties.
Pozzolanic Reaction; A reaction producing a pozzolanic product.
Stabilization: Making stable by physical or chemical treatment.
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ABBREVIATIONS
BOD
Btu
cc
cm
COD
°C
°F
ESP
FGC
FGD
ft
g
gal
gpm
hp
hr
in.
j
j/s
k
kg
kCal
km
kw
kwh
£ or lit
Ib
M
mg
MGD
MW
MWe
MWH
Hg
mil
min
ppm
psi
psia
scf/m
sec
IDS
TOS
TSS
tpy
yr
biochemical oxygen demand
British thermal unit
cubic centimeter
centimeter
chemical oxygen demand
degrees Centigrade (Celcius)
degrees Fahrenheit
electrostatic precipitator
flue gas cleaning
flue gas desulfurization
feet
gram
gallon
gallons per day
gallons per minute
horsepower
hour
inch
joule
joule per second
thousand
kilogram
kilocalorie
kilometer
kilowatt
kilowatthour
liter
pound
million
square meter
cubic meter
milligram
million gallons per day
megawatt
megawatt electric
megawatt hour
microgram
milliliter
minute
parts per million
pounds per square inch
pounds per square inch absolute
standard cubic feet per minute
second
total dissolved solids
total oxidizable sulfur
total suspended solids
tons per year
year
vi
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TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS ill
CONVERSION FACTORS iv
GLOSSARY v
ABBREVIATIONS vi
LIST OF TABLES
X.J_
LIST OF FIGURES xiii
1.0 INTRODUCTION 1-1
1.1 Purpose and Content 1-1
1.2 Report Organization 1-4
2.0 DISPOSAL OF FGC WASTES 2-1
2.1 Disposal Options 2-1
2.1.1 Overview on Technology & Waste Properties 2-1
2.1.2 Matrix of Disposal Options 2-9
2.1.3 Current Disposal Practices 2-9
2.1.4 Current Field Studies 2-20
2.2 Disposal on Land 2-23
2.2.1 Wet Ponding 2-24
2.2.2 Dry Disposal Methods 2-41
2.2.3 Surface Mine Disposal 2-59
2.2.4 Underground Mine Disposal 2-66
2.3 Disposal in the Ocean 2-72
2.3.1 Overview 2-72
2.3.2 Disposal Technology 2-73
2.3.3 Current Studies 2-76
2.4 Disposal Options vs Potential Impact Issues 2-78
2.4.1 Overview on Impact Issues 2-78
2.4.2 Mechanism of Impact 2-82
2.4.3 Issue Definition Process 2-99
2.5 Site Selection, Design and Practice of FGC 2-103
Waste Disposal
2.5.1 Land Disposal 2-103
2.5.2 Ocean Disposal 2-113
3.0 REGULATORY CONSIDERATIONS 3-1
3.1 Regulatory Framework Overview 3-1
3.2 Groundwater Related 3-8
3.2.1 Resource Conservation & Recovery Act 3-8
3.2.2 Safe Drinking Water Act/Underground
Inspection Control Program 3-20
3.2.3 Surface Mining Control and Reclamation Act 3-21
3.2.4 State Regulations 3-23
vii
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VOLUME 5: TABLE OF CONTENTS
(Continued)
Page
3.3 Surface Related 3-24
3.3.1 Introduction 3-24
3.3.2 Surface Water Quality Offgas from
Point Source Discharges 3-25
3.4 State Requirements and Plants 3-39
3.4.1 Present Status 3-39
3.4.2 Responses to Proposal Regulations
under RCRA 3-52
3.5 Ocean Disposal Related 3-56
3.5.1 Statutory Base 3-56
3.5.2 Administration Regulations 3-58
3.5.3 Consideration of Alternatives 3-58
3.5.4 Prohibited Materials 3-59
3.5.5 Other Factors Limiting Permissible
Concentrations 3-60
3.5.6 Monitoring Requirements 3-60
3.6 Stability Related 3-62
3.6.1 Resource Conservation & Recovery Act of 1976 3-62
3.6.2 Surface Mining Control & Reclamation
Act of 1977 3-64
3.6.3 Federal Coal Mine Health & Safety Act
if 1969 3-66
3.6.4 Occupational Safety & Health Act of 1970 3-67
3.6.5 Dam Inspection Act of 1972 3-67
3.7 Land Use Related 3-69
3.7.1 Overview 3-69
3.7.2 RCRA 3-69
3.7.3 Surface Mining Control & Reclamation
Act of 1972 3-74
3.7.4 Land Use Consideration Under State
Regulations 3-81
3.8 Air Related 3-86
3.9 National Energy Act of 1978 3-90
4.0 ENVIRONMENTAL IMPACT CONSIDERATION 4-1
4.1 Introduction 4-1
4.2 Land Disposal 4-2
viii
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TABLE OF CONTENTS
(Continued)
4.2.1 Physical Stability Overview
4.2.2 Public Policy and Land Use
4.2.3 Wet Ponding
4.2.4 Dry Disposal
4.2.5 Mine Disposal
4.3 Ocean Disposal 4-36
4.3.1 Overview 4-36
4.3.2 Impact Assessment 4-36
4.4 Assessment of Present Control Technology 4-41
4.4.1 Introduction 4-41
4.4.2 Site Selection 4-42
4.4.3 Waste Processing Options 4-43
4.4.4 Use of Liners 4-45
4.4.5 Codisposal 4-45
4.5 Summary of Data Gaps and Future Research Needs 4-45
5.0 REVIEW OF MONITORING CONSIDERATIONS 5-1
5.1 Regulatory Requirements for Disposal 5-1
5.1.1 Land Disposal Monitoring 5-1
5.1.2 Ocean Disposal Monitoring 5-3
5.2 Screening Tests for Solid Wastes 5-4
5.2.1 Sample Pretreatment 5-5
5.2.2 Extraction Procedure 5-5
5.2.3 Testing of Extracts 5-6
5.3 Water Monitoring Methods 5-7
5.3.1 Methods for Freshwater 5-7
5.3.2 Methods for Ocean Monitoring 5-8
5.4 Fugitive Emissions Monitoring 5-9
5.5 Biological Monitoring 5-9
5.5.1 Introduction 5-9
5.5.2 Predisposal Baseline Surveys 5-10
5.5.3 Predisposal Bioassay Testing 5-11
5.5.4 Biological Monitoring for Disposal
Operation Compliance 5-13
5.6 Monitoring of Physical Properties 5-15
5.7 Post-operational Monitoring 5-16
5.8 Data Gaps and Future Research Needs 5-17
ix
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TABLE OF CONTENTS
(Continued)
Page
6.0 REVIEW OF ECONOMICS OF DISPOSAL 6-1
6.1 Introduction 6-1
6.2 Generalized Waste Disposal Cost Studies 6-1
6.2.1 Description of Studies 6-1
6.2.2 Disposal Cost Estimates for FGC Wastes 6-9
6.3 Economic (Cost) Impact Stdies 6-22
6.3.1 Radian Study 6-22
6.3.2 SCS Study 6-25
6.4 Economic Uncertainties 6-26
6.5 Data Gaps 6-29
REFERENCES
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LIST OF TABLES
Table No . Page
2.1 Potential Disposal Options 2-10
2.2 Fly Ash Collection - Disposal Practices 2-12
2.3 Fly Ash Disposal Practices by Quantity of Ash 2-13
2.4 Bottom Ash Collection and Disposal Practices 2-14
2.5 Bottom Ash Disposal Practices by Quantity of Ash 2-15
2.6 Nonrecovery FGC System is Commercial Operation
on Utility Boilers 2-17
2.7 Nonrecovery FGD Systems in Commercial Operation on
Industrial Boilers ' 2-18
2.8 Summary of Disposal Practices for Operational
FGC Systems on Utility Boilers as of
November 1978 2-19
2.9 Summary of Current Field Testing Programs
for FGC Waste Disposal 2-22
2.10 Summary of Land Disposal of FGC Wastes 2-24
2.11 Typical FGC Waste Disposal Operations -
Wet Disposal 2-25
2.12 Potential FGC Waste Disposal Impact Issues 2-79
2.13 Disposal Options VS Potential Environmental
Impact Issues for FGC Wastes 2-80
2.14 Relative Potential for Water-Related Impacts
From Different FGC Waste Disposal Options 2-92
2.15 Status of Issue Definition by Regulations
Governing Disposal of FGC Wastes 2-101
2.16 FGC Waste Disposal Site Evaluation Parameters 2-105
3.1 Regulatory Framework for Coal Ash and FGD Sludge
Disposal/Utilization 3-9
3.2 Effluent Parameters Subject to Effluent Guidelines
Limitations for the Steam Electric Power Generation
Category 3-26
3.3 Comparison of FGC Waste Liquors with Water Criteria 3-28
3.4 Discharge Criteria in New York and Missouri 3-29
3.5 Management and Disposal of Solid Wastes In States 3-40
3.6 PSD Limits on Increases in Pollutant Levels 3-88
xi
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LIST OF TABLES
(Continued)
Table No. Page
4.1 Cumulative Land Requirements for Disposal
of FGC Wastes 4-38
4.2 Observations of Mounds of FGC Wastes Created
in Shallow Water Environment , _q
6.1 Summary of General Conceptualized Cost
Studies - FGC Wastes 6-2
6.2 Summary of Basic Assumptions for General
Cost Studies - FGD Wastes 6-4
6.3 Summary of TVA Cost Estimates for Wet Ponding 6-11
6.4 Comparison of Generalized Costs for Wet Ponding
Unstabilized FGC Wastes 6-13
6.5 Summary of TVA Estimates for Dry Impoundment 6-16
Disposal Systems
6.6 Summary of Mine Disposal of FGC Wastes 6-19
6.7 Summary of Preliminary Cost Estimates for Ocean 6-20
Disposal of FGC Wastes
6.8 Summary of Estimated Cost of Compliance 6-28
6.9 Summary of Regulatory Impacts to Consumers 6-27
in Mills/kWh
xii
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LIST OF FIGURES
Figure No .
2.1 Waste Handling Colstrip Plant Montana
Power Company 2-26
2.2 Handling LaCygne Station, Kansas City
Power & Light Company 2-27
2.3 Waste Handling St. Clair Plant - Detroit
Edison Company 2-28
2.4 Waste Handling Sherburne Plant -
Northern States Power Company 2-29
2.5 Waste Handling - Bruce Mansfield Plants -
Pennsylvania Power Company 2-30
2.6 Pond Designs 2-34
2.7 Proposed Gypsum Pond Water Seepage Control
System Using a Collection Ditch Around the
Perimeter (EPA Effluent Guidelines Document) 2-37
2.8 Typical Landfill Scheme for Sulfate-Rich or
Gypsum Wastes 2-45
2.9 Untreated Waste Fly Ash Blending 2-46
2.10 FGC Waste Disposal Using a Stabilization Process 2-49
2.11 Schematic of IUCS "Stabilization" Process at
Conesville 2-51
2.12 General Landfill Designs 2-57
2.13 Area Strip Mining with Concurrent Reclamation 2-61
2.14 FGC Disposal Site Selection Process Logic Diagram 2-104
3.1 FGC Wastes - Federal Regulatory Chart 3-5
3.2 Regulatory Requirements - RCRA 3-14
4.1 Oxygen Depletion Rates in Well-Agitated Slurries
of FGC Wastes 4-38
4.2 Observations of Mound of FGC Wastes Created
in Shallow Water Environment 3-39
xiii
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1.0 INTRODUCTION
1.1 Purpose and Content
As coal utilization in utilities and large industrial boilers
increases, the quantity of flue gas cleaning (FGC) wastes, particularly
those associated with flue gas desulfurization (FGD), will increase dramati-
cally. The preponderant part of these FGC wastes will be sent for disposal.
Over the long term, utilization is expected to grow but at a slower rate
than that of FGC waste generation. Projections of coal ash and FGD
wastes through 2000 were provided in Volume 3.
In the past, utilities operating FGC systems have typically disposed
of wastes by storage in ponds, often without provision for control of over-
flows or seepage into groundwater. However, several factors will dra-
matically influence disposal options in the coming years.
a. An increase in coal-fired capacity in the United States.
In 1976 the total U.S. coal-fired electric utility generating
capacity was estimated at over 191,000 MW in 399 plants [1].
The estimated capacity is expected to increase by 1986 to over
326,000 MW [2]. Use of coal in large industrial boilers (+25 MW
equivalent or larger) is likely to further increase the total
coal-fired capacity [3,4].
b. A major increase in the application of scrubber technology
by utilities and a consequent increase in FGD waste genera-
tion. At present,over 16,000 MW of generating capacity at
some thirty plants utilize FGD systems. As of September
1978, over 59,000 MW of capacity have been committed[5].
Future increases are likely to be even more dramatic.
c. Advances in stabilization technology for FGD wastes which
permit landfill disposal of partially dewatered solids
instead of ponding of difficult to handle sludges. In the
future, disposal of wastes in managed fills is likely to
be encouraged. In many cases this will require stabilization
prior to disposal.
1-1
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d. Regulatory developments including the Clean Air Act of 1977
and the Resource Conversation & Recovery Act of 1976 (RCRA).
The recent issuance of proposed guidelines provides impetus to
environmentally sound disposal of FGC wastes [6]. New Source
Performance Standards (NSPS) for criteria pollutants are now
under review by the EPA and may be significantly tightened.
Thus, disposal of FGC wastes will require major and continuing focus on
potential environmental impacts.
This is the fifth in a five-volume report assessing technology
for the control of waste and water pollution from combustion sources.
This volume reports on the status of FGC waste disposal including both
current commercial practice and ongoing R&D programs. The focus of this
volume includes the technical, economic, regulatory and environmental
aspects of ongoing technology development and commercialization of FGC
waste disposal. FGC wastes considered in this report include FGD wastes
primarily from non-recovery systems.
The primary focus of this report is on coal-fired power plants;
however, many of the characteristics discussed would also apply to wastes
from oil-fired boilers. Coal-fired power plants generate the maximum
range of waste types and usually the greatest quantity. Thus, they can
serve as the logical focus for assessing environmental and technological
problems relating to the disposal and utilization of waste materials.
A coal-fired power plant produces two broad categories of coal-
related wastes:
• Coal ash, which includes both fly ash and bottom ash (or boiler
slag), and
• Flue gas desulfurization (FGD) wastes from the control of sulfur
dioxide emissions.
Together, fly ash and FGD wastes are generally referred to as flue gas
cleaning (FGC) wastes. In many cases, fly ash and S0~ emissions are
separately controlled and represent separate waste streams. In other
cases, fly ash and FGD wastes are combined in a single stream, either
-------
through admixture of these wastes or through simultaneous collection of
fly ash and SO-- This review of FGC waste includes coal ash, FGD wastes,
and their combination both as produced directly from FGC systems as well
as wastes processed for disposal.
The review and assessment has involved two separate efforts as
described below:
1. Review of the data and information available as of February 1979
on the disposal of FGC wastes. The review is based upon
published reports and documents as well as contacts with private
companies and other organizations engaged in FGC technology
development or involved in the design and operation of FGC
systems and waste disposal facilities. Much of the information
has been drawn from the waste disposal and characterization
studies and technology development/demonstration programs
sponsored by the Environmental Protection Agency (EPA) and
the Electric Power Research Institute (EPRI).
2. Based upon the review of the data and assessment of ongoing
work in waste disposal, identification of data and
information gaps relating to waste properties and the develop-
ment of recommendations for potential EPA initiatives to assist
in covering these gaps. The principal purpose of this effort
is to ensure that, ultimately, adequate data will be available
to permit reasonable assessment of the impacts associated with
the disposal and/or utilization of FGC wastes.
Throughout this work, emphasis has been placed upon wastes produced by
commercially demonstrated technologies and, where data are available, by
technologies in advanced stages of development that are likely to achieve
commercialization in the United States in the near future. In terms of
FGD wastes, consideration is limited to non-recovery FGD systems with
focus on those producing solid wastes (rather than liquid wastes). There
are very few recovery systems in operation or under construction in the
United States, and these generally produce a small quantity of waste in
comparison to non-recovery systems.
1-3
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1.2 Report Organization
Complete assessment of FGC waste disposal is site- and system-specific.
With that understanding, this volume presents a broad overview on the
following subjects to provide a generic baseline for environmental
assessment:
• Description of disposal options studied or practiced today,
• Definition of potential impact issues,
• Assessment of environmental impacts,
• Review of monitoring considerations, and
• Review of FGC waste disposal economics.
1-4
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2.0 DISPOSAL OF FGC WASTES
2.1 Disposal Options
2.1.1 Overview on FGC Technology and Waste Properties
Coal-fired industrial and utility boilers generate two types of
combustion-related wastes:
• Coal ash, including fly ash and bottom ash
(or boiler slag), and
• FGD wastes from the control of SC^ emissions.
The technology of ash collection and flue gas desulfurization (FGD),
the characteristics of the wastes produced, and projections on waste
generation were discussed in Volume 3. This chapter provides a review
of disposal options both current and potential. Emphasis is placed on
fly ash and nonrecovery FGD process wastes since these will be the
principal products in the next few years.
Detailed physical and chemical characterization of FGC wastes is
provided in Volume 3. Some aspects of FGC wastes will be considered
here to place disposal options in perspective.
2.1.1.1 Coal Ash
The total amount of coal ash produced is a function of the ash
content of the coal. The partitioning of coal ash between fly ash and
bottom ash (or boiler slag) is dependent on the type of boiler and its
general operating condition. Standard pulverized-coal-fired boilers
typically produce about 80-90% of the ash as fly ash. In cyclone-fired
boilers, frequently used to burn lignite, the fly ash fraction is usually
less; in some cases, bottom ash constitutes the majority of the total
ash generated.
Collection of bottom ash (or boiler slag) does not involve systems
outside the boiler itself. The key technology issue is the handling of
bottom ash. Fly ash, however, is a major source of particulate emissions
and, with regulatory requirements, has required major collection systems.
Control of particulate emissions from pulverized-coal-fired steam gener-
ators is rapidly becoming a significant factor in the siting and public
2-1
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acceptability of coal-burning power plants. The particulate emissions
limit under current NSPS set by the EPA for large, new coal-fired boilers
is 0.043 grams/106 joules (0.1 lb/106 Btu). Some states have requirements
more restrictive than this. Furthermore, the NSPS are now under review
and are expected to be tightened significantly. Tightening regulatory
posture indicates the following:
• For reliable service in new large systems, fly ash will be
collected separately from wet scrubbing-based FGD systems.
In the past, simultaneous collection of both fly ash and
SOX has been practiced. If dry sorbent FGD systems are
used, simultaneous collection will be practiced.
• Fly ash collection will be based primarily on electrostatic
precipitators (ESP's) or fabric filters. Mechanical collection
may be employed only to supplement the above two types of
particulate collectors.
The chemical composition of coal ash (bottom ash, fly ash, and slag)
varies widely in concentrations of both major and minor constituents. The
principal factor affecting the variation in the composition is the vari-
ability in the mineralogy of the coal. However, differences in composi-
tion can exist between fly ash and bottom ash (or boiler slag) generated
from the same coal because of differences in the degree of pulverization of
the coal prior to firing, the type of boiler in which the coal is fired,
and the boiler operating parameters and combustion efficiency. Regard-
less of the type of ash (either fly ash or bottom ash), more than 80% of
the total weight of the ash is usually made up of silica, alumina, iron
oxide, and calcium oxide. It should be noted that the compositional
breakdown usually shown in the literature (including Volume 3) reflects
only the elemental breakdown of the constituents reported as their oxides
and not necessarily the actual compounds present.
While the major constituents of bottom ash and fly ash are generally
similar, there is usually an enrichment of trace elements in the fly ash
as compared with the bottom ash based upon the total quantity of trace
elements in the coal fired. A few of the elements originally present in
2-2
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the coal (notably sulfur, mercury, and chlorine) are almost completely
volatilized and leave the boiler as gaseous species which are not col-
lected downstream in dry ash collection equipment. However, these can
be collected in wet scrubber systems.
Up to 10% of fly ash can be water-soluble, so the potential exists
for release of contaminants through leaching. The principal soluble
species are usually calcium, magnesium, sodium, potassium, sulfate, and
chloride. Leachates resulting from ash are usually alkaline due to the
presence of calcium oxide and other alkaline species, although some ashes
have been found to be inherently neutral or even acidic.
The physical properties of fly ash vary with the type of coal fired,
the boiler operating conditions, and the type of fly ash collector employed.
A mechanical collector, which generally removes only the heaviest fly ash
fraction, produces a relatively coarse material with the consistency of a
fine sand. In contrast, the ash removed in an electrostatic precipitator
is usually finer, with a silt-like grading. The range of specific gravi-
ties of fly ash depends upon particle size distribution and fly ash com-
position; however, specific gravities typically range from approximately
1.9 to 2.7. Usually a small portion of the fly ash consists of cenospheres
(hollow spheres) which have an apparent density less than water. Bulk
densities of fly ash, because of the variations in specific gravity and
particle size distribution, vary greatly; although, a typical range for
3
fly ash compacted at optimum dry density would be 1.1-1.79/cm (70-105
lb/ft3).
An important property of coal fly ash is its pozzolanic activity.
Pozzolanic activity refers to the ability of fly ash to aggregate and
harden when moistened and compacted due to reactions with lime either
present in the ash or admixed with the ash. Because the degree of
pozzolanic activity can vary greatly, there can be considerable variation
in the engineering and structural properties of fly ash. Ashes from most
lignite and some subbituminous coals, for example, have relatively high
calcium levels (>10% measured as calcium oxide) and, as such, usually
exhibit significant self-hardening properties. However, in general,
2-3
-------
unstabilized fly ash (that to which lime has not been added intentionally)
usually exhibits engineering properties similar to soils of equivalent
particle size distributions. Permeabilities of compacted fly ash samples
generally range from 5 x 10~^ cm/sec to 5 x 10~5 cm/sec. (See Volume 3,
Reference 70,82,83.) Stabilization of pozzolanic fly ashes with lime can
result in significant increases in compressive strength and decreases in
permeability (depending upon the amount of lime, the water content, curing
time, and degree of compaction).
Bottom ash can be collected either dry or in a molten state, in
which case it is generally referred to as boiler slag. Dry-collected
bottom ash is heavier than fly ash, with a larger particle size distribu-
tion. Since it has a similar chemical composition to that of fly ash,
it behaves similarly, although pozzolanic activity is usually somewhat
less in bottom ash.
Boiler slag is a black, glassy substance created by water quenching
of the molten ash. It is composed chiefly of angular or rod-like particles,
with a particle size distribution ranging from fine gravel to sand. Boiler
slag is porous, although not of so great a porosity as dry bottom ash. It
is generally less reactive in terms of its pozzolanic properties than either
dry bottom ash or fly ash. Because of the similarities between bottom and
fly ashes, they are generally grouped together for environmental impact
assessments.
2.1.1.2 FGD Wastes
FGD systems are generally categorized into two groups:
• Nonrecovery or throwaway systems which produce a solid or
liquid waste with little market value at present, and
• Recovery systems that produce elemental sulfur or sulfuric
acid as a byproduct for sale.
At present, the overwhelming majority of FGD systems for controlling
emissions from industrial and utility boilers utilize some form of non-
recovery system. Over 90% of the 59,000 MW committed to FGD systems
involve nonrecovery processes [5]. This dominance of nonrecovery pro-
cesses is expected to continue over the next ten years.
2-4
-------
Commercially available nonrecovery processes can be conveniently
subdivided into two groups according to the form of the waste materials
produced—those which convert the 862 into a solid waste and those which
produce a liquid waste. Nonrecovery systems can also be classified
according to the manner in which the flue gas is contacted with the
S02 sorbent—i.e., wet scrubbing processes versus dry processes.
All nonrecovery systems now in commercial operation on utility and
industrial boilers are wet processes involving contact of the gases with
aqueous slurries or solutions of absorbents. Although most nonrecovery
systems can withstand relatively high levels of particulate and trace
contaminants and many in the past have been designed for simultaneous
S02 and particulate control, most systems being installed today on utility
boilers are downstream from high efficiency electrostatic precipitators
in order to ensure more reliable service. The notable exceptions are
systems designed to utilize alkalinity in the fly ash for all or part
of the SC>2 removal. These frequently incorporate simultaneous fly ash
and S02 control.
Dry processes have not yet been demonstrated commercially on a
utility scale in the United States. However, a number of different
approaches have been investigated, including dry injection of sorbents
into the boiler and flue gas and the use of spray dryers. All of these
involve simultaneous 862 and particulate control, and all produce a dry
waste material. The most promising approach at present employs spray
dryers for contacting the flue gas with slurries (or solutions) of
calcium hydroxide or sodium carbonate/bicarbonate. Three such systems
have been contracted for application to utility-scale boilers.
Solid Wastes
The four basic types of nonrecovery systems producing solid wastes
are:
• Direct lime scrubbing,
• Direct limestone scrubbing,
• Alkaline fly ash scrubbing, and
• Double (dual) alkali.
2-5
-------
The first three of these utilize slurries of lime, limestone, or
ash to contact the flue gases and produce slurries containing 5-20 wt%
solids which are either discharged directly or partially dewatered and
possibly further processed prior to discharge. All three of these are
commercially demonstrated technologies. The fourth, the double alkali
process, is a second generation technology which has been applied success-
fully to industrial-scale boilers but is only now reaching commercial
demonstration on utility boilers. Double alkali processes utilize
solutions of sodium salts for SOo removal, which are then regenerated
using lime to produce a waste solid that is discharged as a filter cake.
In addition, dry sorbent based FGD systems are also likely to be
in commercial use by the early 1980's. These will be based on lime,
sodium salts or other sorbent and will produce dry solid wastes. To
date, the extent of focus on utilization of such dry sorbent wastes
has been minimal.
The quantity and composition of ash-free FGD wastes are dependent
upon a number of factors including: coal characteristics (most impor-
tantly, its sulfur content and heating value); SO™ emissions regulations;
the type of boiler and its operating conditions; and the type of FGD
system and its operating conditions. In general, the quantity of dry,
ash-free FGD waste produced varies from about 2.0 to about 3.5 times the
quantity of S02 removed from the flue gas. Hence, a typical utility
boiler operating at a 70% load factor could produce anywhere from 50 to
500 tons of dry, ash-free solids annually per megawatt of boiler capacity.
The principal substances making up the solid phase of FGD wastes are
calcium-sulfur salts (ralciuii. sulfite and/or calcium sulfate) along with
varying amounts of calcium carbonate, unreacted lime, inerts and/or fly
ash. In wet processes the ratio of calcium sulfite to calcium sulfate
is a key design and operating parameter, especially for direct scrubbing
systems since it can affect not only the scale potential of the system
but also the waste solids properties. The relative amounts of calcium
sulfite and sulfate present depend principally upon the extent to which
oxidation occurs within the system. Oxi '.ation is generally highest in
2-6
-------
systems installed on boilers burning low sulfur coal or in systems where
oxidation is intentionally promoted. In most medium to high sulfur coal
applications, oxidation of sulfite to sulfate in the scrubber system
amounts to only 10-30%, and calcium sulfite is the predominant material
in the waste. When the sulfate content of the waste solids is low,
calcium sulfate usually is present as the hemihydrate salt (CaSO, •
1/2H20). At higher calcium sulfate levels, gypsum (CaSO, • 2H 0)
becomes the predominant form of calcium sulfate. At very high levels
of oxidation (greater than 90% oxidation of the SO,, removed) all of the
calcium sulfate will usually be present as gypsum.
Because the differences in the crystalline morphology of hemihydrate
and dihydrate solids not only reflect the chemical composition but also
can affect the physical and engineering properties, it is convenient to
classify FGC wastes on the basis of the ratio of calcium sulfate to
total calcium-sulfur salts. The three categories are as follows:
• Sulfate rich (CaSO./CaSO > 0.90),
4 X
• Mixed (0.25 < CaSO./CaSO < 0.90), and
T1 X
• Sulfite rich (CaSO,/CaSO < 0.25),
4 X
where CaSO is the total calcium-sulfur salts.
X
Calcium sulfite wastes present a problem because of the difficulty
of dewatering. The slurry can be dewatered only to about 50-60% solids,
producing an unstable, thixotropic material. However, calcium sulfite
wastes can be oxidized to calcium sulfate, either intentionally in the
scrubber or in an external oxidation reactor. From the viewpoint of
utilization, calcium sulfate is the desirable FGD byproduct.
EPA studies at the Industrial Environmental Research Laboratory
(Research Triangle Park, North Carolina) have shown that calcium sulfite
can be readily oxidized to gypsum by simple air/slurry contact in the hold
tank of the scrubber recirculation loop. Although the rate of oxidation
reaches a maximum at a pH of 4.5 and then declines at higher pH, it was
found that oxidation could be accomplished at a practical rate up to a pH
of about 6.0 [38].
2-7
-------
In Japan, where natural gypsum is not available, forced oxidation
in scrubber systems has been employed extensively to produce a high-
quality gypsum raw material for the cement and wallboard industries.
In the United States, scrubber gypsum may be unable to compete exten-
sively with the widely available natural gypsum. Thus, the incentive
in the United States has been to develop simplified forced oxidation
procedures directed only toward improving waste solids handling and
disposal properties. As a disposal material, the gypsum waste can
have high fly ash content; moreover, the oxidation reaction need be
carried only to about 95% completion.
There is little information currently available on the composition
of wastes from dry scrubbing systems utilizing spray dryers. However,
while all of these would contain fly ash, the fraction of the waste
resulting from S02 control would be expected to be similar in chemical
composition to those produced by wet processes using the same sorbents.
For lime-based dry scrubbing, the FGD wastes should consist primarily of
a mixture of calcium sulfite, sulfate, and unreacted lime. The quantity
of unreacted lime, however, may be somewhat higher than in wet scrubbing
wastes owing to the higher stoichiometries that would probably be
required. The mix of calcium sulfate and sulfite solids may also be
somewhat different, both in terms of their relative quantities as well
as the crystalline forms present.
For dry systems utilizing alkaline sodium salts (e.g., nahcolite
or sodium bicarbonate) the waste solids would be expected to contain in
addition to fly ash a mixture principally of sodium sulfate, sulfite,
chloride, and unreacted carbonate. These would be similar, then, in
composition to the wastes produced from once-through sodium solution
scrubbing except that the solids would be discharged as a dry material
rather than'as a liquid.
Liquid Wastes
There are two different liquid waste-producing FGD processes that
are in commercial operation on combustion boilers—(1) once-through scrub-
bing using solutions of alkaline sodium salts, and (2) scrubbing with
ammonia-laden water. Of the two, once-through sodium scrubbing has achieved
2-8
-------
the widest acceptance, having been applied to many industrial steam
plants and a few utility boilers. Once-through sodium scrubbing pro-
duces a waste liquor containing primarily sodium sulfate, sulfite, and
chloride at total dissolved solids concentrations generally in the range
of 15-30 wt%. Most of these waste liquors also contain significant partic-
ulate levels since the systems are used ^or combined particulate and SO
control. Frequently, the waste liquors are air-sparged to oxidize any
residual sulfite to sulfate, especially where wastes are discharged for
disposal.
2.1.2 Matrix of Disposal Options
Numerous methods are potentially available for the disposal of FGC
wastes, the ultimate recipient being land or the ocean. The feasibility
of disposal options can be categorized broadly on the basis of the nature
of the wastes and the manner (type) of disposal.
Table 2.1 lists potential disposal options for the various types
of FGC wastes which can be generated. An indication is given as to
which options are being practiced on a commercial scale and which
remain as reasonable potential. Sulfur is included in this table
since long-term storage or even disposal of sulfur may be necessary
in some applications of recovery systems. However, it is unlikely
that many sulfur producing recovery processes would be installed
without well-defined plans for sulfur utilization or marketing.
2.1.3 Current Disposal Practices
2.1.3.1 Current Fly Ash Disposal Practices
Disposal of fly ash or bottom ash is currently practiced at some
390 plants in the United States where coal is utilized at least as a
part of the boiler fuel [6]. A complete survey of disposal practices
is not available, although some general indications are available in
FPC Form 67 data [6]. Such data, though, are sketchy and do not include
handling information.
Radian [7], in a recent study, undertook a survey of 64 plants with
a total capacity of 50,900 MW to develop some baseline information on
ash disposal practices. Most of the plants contacted began operation
2-9
-------
Table 2.1
Potential Disposal Options
Ash FGD Waste Codisposal Sulfur
Land Disposal
Wet Pond - Conventional
Stacking (Gypsum)
Dry Impoundment
Surface Mine
Underground Mine
C
C
P
C
P
C
P
P
C
P
C
C
P
P
P
P
Ocean Disposal
Shallow - Outfall
Concentrated (con-
ventional) Dump
Dispersed Dump
Reef Construction
(Stabilized)
Deep - Concentrated (con-
ventional) Dump
Dispersed Dump
P
P
P
P
P
P
P
P
P
P
P
P
C - commercial practice
P - reasonable potential
2-10
-------
in 1970-1978 and hence were relatively new. The data were characterized
according to the disposal method used for each type of solid waste, the
total coal-fired generating capacity of the plant, the solid wastes
collection equipment and the type of FGD systems used. The data obtained
are summarized in Tables 2.2 and 2.3. Provided the survey sampling is
statistically representative of the industry (or, at least, the newer
fraction of total capacity), it appears that:
• While a greater number of plants use ponding of fly ash,
the greatest quantity of material is disposed by landfill.
Radian reports that, of the 45 plants providing detailed
information (representing about 36,000 MW), none sold their
fly ash, but some of the paid disposal includes material
that was eventually sold.
• The majority of plants use ESP to collect dry fly ash but
dispose of the ash by ponding; only 30% of the plants have
dry fly ash handling and disposal.
• Nearly 17% of the plants pay another company to dispose of
or otherwise haul away the ash and 5% sell the ash directly
to some company. In addition, a significant amount of the
fly ash removed by paid disposal may be sold and utilized.
Thus, the total amount of ash utilized is difficult to
determine from the disposal data.
Considering the emergence of bag filters for fly ash collection and
regulatory developments, the disposal of fly ash in managed fills in a
relatively dry state (with water for fugitive emissions control only) is
likely to be a major option.
2.1.3.2 Current Bottom Ash Disposal
The above-mentioned Radian survey [7] also included data on bottom
ash disposal which is summarized in Tables 2.4 and 2.5. Providing the
data are statistically representative of the industry, it appears that:
• On a plant basis, the vast majority wet sluice bottom ash
but less than half of these plants use ponding for dis-
posal. It is not known why this discrepancy exists.
2-11
-------
Table 2.2
Fly Ash Collection and Disposal Practices
Basis: Radian Corporation Survey in 1978 for EPA
Number of Plants Percent of Plants
Method Reporting Method Reporting Method
I. Collection
Dry Electrostatic Precipitator . 39 61
Mechanical (Baghouse, etc.) 8 13
Wet Electrostatic Precipitator 4 6
Particulate Scrubber 2 3
Other 11 17_
Total 64 100
II. Disposal
Ash Pond 26 40
Conveyed to Landfill (Dry) 19 30
Paid Disposal 11 17
Sale of Fly Ash 3 5
Intermediate Ponding followed
by Landfill 3 5
Other _2_ 3
Total 64 100
Source: [7]
2-12
-------
Table 2.3
Fly Ash Disposal Practices by Quantity of Ash
Basis: Radian Corporation Survey in 1978 for EPA
Amouut Percent
Disposal Method (10 metric tons/yr) of Total
Ponded 3,148 34
Landfill 4,763 51
Paid Disposal 1,415 15
Sold
Other 3 ^
Total 9,329 100
Source: [7]
2-13
-------
Table 2.4
Bottom Ash Collection and Disposal Practices
Basis: Radian Corporation Survey in 1978 for EPA
Method
I. Collection
Wet Sluiced
Dry Conveyor
Other
Total
Number of Plants
Reporting Method
52
11
_±
64
Percent of Plants
Reporting Method
81
17
2
100
II. Disposal
Ash Pond
Conveyed to Landfill (Dry)
Paid Disposal
Sale of Bottom Ash
Intermediate Ponding Followed
by Landfill
Other
24
17
8
6
Total
64
38
27
12
9
9
5
100
Source: [7]
2-14
-------
Table 2.5
Bottom Ash Disposal Practices by Quantity of Ash
Basis: Radian Corporation Survey in 1978 for EPA
Amount Percent
Disposal Method (10 metric tons/yr) of Total
Ponded 1,763 44
Landfill 1,138 29
Paid Disposal 671 16
Sold 444 11
Total 4,016 100
Source: [7]
2-15
-------
Mechanical dewatering and dry disposal of bottom ash
do. not appear to be common practice.
• On a quantity basis, the most common disposal method
is ponding.
However, it is well to note that regulatory developments and economics
may tend to encourage disposal of dewatered wastes in managed fills
in the future.
2.1.3.3 Current FGD Waste Disposal
As of the end of 1978, nonrecovery FGD systems were in operation at
28 power stations and more than 40 industrial steam plants throughout
the United States. Another eleven wet particulate scrubbing systems
were also in operation at utility power plants. Although SC>2 control
was not the primary function of these latter systems, they did achieve
some degree of 862 removal, producing a waste containing a significant
fraction of S02~related wastes. Including wet particulate scrubbing on
utility boilers, the total FGD capacity amounted to an equivalent of
about 21,000 MW.
Tables 2.6 and 2.7 summarize the operational FGD systems on utility
and industrial applications at the end of 1978. The data shown in these
tables were obtained from PEDCo reports [4, 5 ] and utility and indus-
trial plant contacts.
Of the operational utility FGD systems listed in Table 2.6, all but
that at Nevada Power Company's Reid Gardner Station produce a solid waste
of calcium-sulfur salts. In contrast, the overwhelming majority of FGD
systems on industrial boilers convert the S02 removed to a liquid waste
of soluble sodium salts. Thus, while there are no definitive data on
waste generation rates, it is clearly evident that most of the wastes
being produced are solid wastes, and that essentially all of it is being
generated by utility FGD systems. This is a trend which is expected to
continue at least over the next ten years.
In order to gain a better perspective of waste generation and disposal
in utility FGD systems, the information provided in Table 2.6 has been
compiled in Table 2.8 according to waste type, disposal mode and general
plant location. This compilation points out some interesting trends
in current utility waste generation and disposal practices.
2-16
-------
Table 2.6
Nonrecovery FGC Systems in Commercial Operation on Utility Boilersc
t-o
i
SOj camoL SYSTEMS.
Alabena Electric Coop
Arlaoaa Electric Power Coop
Arlaona Public Service
Central Illlnola Light
City Utllltle. of Springfield
Coluabua ft Southern Ohio
Hueueane Light
Indlanapolle Power • Light
Kenaae City Power 6 Ll(ht
(aneee Poor 6 Light
Kentucky Utllltle.
Lo.lKllle Can 1 Electric
mnnkota Power
Nontene Pont
Northern. State* Power
PanBtaylven.la Power
Southern Carolina Public Service
toutken Mleele.lnpl Electric
T.IM1..... Valley Authority
Temaa Utllltla.
Otoh Power 4 Light
PAHTICULATE CONTtOL STSTOg
- »TT SCHUlaO:
Arleoae Public Servlcee
CiiJiiilnialth Edlaon
Detroit tdleon
Ulnneoot. Power 4 Light
Nentnae - Denote Dtllltlee
Nevada Power
Pacific Power 4 Light
Publle Service Cowpaav of Colorado
Southweet Public S«r»lcc»
To-hlghea dolt 2)
Ap'cha (Unl: 2)
CholU (Unl:. U2)
Duck Cr.ek Unit 1)
Southv.it (l.nlt 1)
ConcayllU 'Unit. }to)
ClriM (U«ln 1-*)
Phillip. (Urlt. 1-6)
Pet.raburg (Unit 3)
taothonw (iinlca U<)
UCyn« (Unit 1)
J.fferoy (Unit 1)
Lovrenc. (Urlt. 4iS)
Cr«n ll»r (Unit* 1-3)
Can. Hut (Utlta 445)
Hill Creek (Unit 3)
Peday'e tun (Unit 6)
Hilton I. YOiUl (Unit 2)
Col.trip (Unite 142)
Shetbume (U.ilte 142)
truce HeaefleU (Unit. 142)
Hlnyeh (Unit 2)
I.D. Norton (Uo.lt 1)
Uldou'a Creek (Ue.lt I)
Martin Lake ;Unlt. 142)
hontlcrllo (»elt ))
Huntlngtoe (lalt 1)
Pour Comer. (Unit. 1-3)
Hill County (Unit 1)
St. Clelr (Cult e)
Aurora (Ualt. 1(2)
Clay joeu.ll (Unit 3)
Loul. 4 Clerk (Unit 1)
laid Caraner (Unit. 1-1)
Hac
350
Coal Sulfur
Content (I)
0.5-1.0
0.5
2.5-3.0
3.5
4.5-5
2.0
2.0
3-3.5
0.5-1
5.0
0.5
0.5
4.0
3.5-4.0
3.5-4.0
3.5-4.0
0.7
O.S
O.S
4.0-5.0
1.0
1.0
3.0-4.0
1.0
1.5
0.5
O.S
<1.0
0.3
1.0
1.0
0.7
0.5
0.5
0.6-1.0
0.6
0.7
0.5
Scrubbing Syateat
Mode
SOj
SO,
SOj + Aah
SO,
so,
S02
SO, + Aah
SO, * Aah
SO,
SO, + Aah
SO, + Aah
SO,
SO, + Aah
SO, + Aah
SO,
SOj
SO,
SO,
SO, + Aah
SO, + Aah
SO, + Aah
SO,
SO,
so,
S02
so.
S02
Aah
Aah
Aah
Aah
Aeh
Aeh
Aah
Aeh
Aeh
Aah
Aah
Aah
Alk.ll
Llneatone
Llneetone
Lleeetooe
Llneetone
Llneatone
Line (Thloeorblc)
Line (Thloaorblc)
Line (Thloeorblc)
Llneatone
Line
Llneatone
Llneatone
Llneatone
Line
Line (Carbide)
Line (Carbide)
Line (Carbide)
Aah (+ Line)
Aah (+ Line)
Llneatone
Line (Thloaorblc)
Llneatone
Llajcatone
Lleeetone
Lleeatone
Llneetone
Line
Source
Thickener
Scrubber
Scrubber
Thickener
Fllte
Fllte
Fllte
Fllte
Fllte
Thickener
Scrubber
Scrubber
Thickener
Scrubber
Thickener
Thickener
Filter
Filter
Settling Pond
Thickener
Thickener
Thickener
Filter
Scrubber
Filter
Scrubber
Filter
(Line) Thickener/Settling Pond
(Llneetone)
none
None
None
(Llaetetone)
(Soda Aah)
(Line)
None
Thickener
Scrubber
Scrubber
Thickener
Scrubber
Scrubber
Settling Pond
Settling Pond
None Thickener/Settling Prod
None
(Llneatone)
Settling Pond
Thickener
Unate For.
Proceaaloa.
Nona
None
None
Aah Added
Nonproprletary Stab. (Aah + Line)
Connerclal Stab. (IUCS)
r-i irclal Stab. (IUCS)
Coaejerclal Stab. (IUCS)
Connerclal Stab. (IUCS)
None
Nona
Aah Added
None
Nona
Nona
Nona (Codlapoaal la Aah Pond)
None (Codlapoaal In Aah Pit)
None
None
(Forced Oxidation)
Coneerclal Stab. (Dravo)
Nona
Nona
Aah Added
Aah Added
None (Codlepoeal In Aah Pond)
'Aah Added
None
Nonproprletary Stab. (Aah * Line)
None
Nona
None
None
Nona
None
Line Added
Line Added
Lleeetooe Added
None
Final Olapoaal
Uet Pond (L)
Uet Pond (u)
wet Pond (u)
wet Pond (u)
Dry Fill
Dry Fill
Dry Fill
Dry Fill
Dry Fill
Uet Pond (u)
Uet Pond (u)
Uet Pood (L)
Uet Pond (u)
wit Pond (u)
Uet Pond (u)b
Uet Pond (u)»
Dry Fill
Dry Pill (Mine)
Uet Pond (u)
Uet Pond (L)
U*t Pond (u)
Uet Pond (u)
Dry Pill
net Pond (u)
Dry Fill (Mine)
UetOlbd (u)
Dry Fill
Dry Fill (Mine)
Dry Fill
U. Pond (L)
Ue Pond (u)
Ue Pond (u)
Ue Pond (L)
We Pond (u)
Dry Pill
Dry Pill
Dry Pill
Dry Fill
Hat Pond (u)
'tnela: Nmmber 1*71
kMapoeal operation. Kill be converted la 1»7» to err
alf of boiler capacity la acrubbed
t with etabllliatlon.
Source: Arthur D. Little, Inc.
-------
Table 2.7
Nonrecovery FGD Systems in Commercial Operation on Utility Boilers0
to
h-1
CO
Company
SOLID HASTE;
Araco Steel
Caterpillar Tractor
Firestone Tire & Rubber
General Motors
Rickenbacker Air Force Base
LIQUID HASTE!
Alyeska Pipeline Service
American Thread
Beldrldge Oil
Canton Textiles
Chevron U.S.A.
FMC
General Motors
Georgia Pacific
Getty Oil
Great Southern Paper
Great Western Sugar
ITT Eayonler
Xerr-McGee Chemical
Minn-Dak Farmer's Coop
Mobil Oil
Sheller Globe
St. Regis Paper
Texaco
Texas Gulf
Plant
Middle tovn, OH
East Peoria, IL
Jollet, IL
Morton. IL
Mosavllla. IL
Pottstovn , PA
Parma, OH
Columbus, OB
Valdez, AK
Marlon, NC
McKit trick, CA
McKlttrick, CA
Canton, GA
Bakersfield, CA
Green River, HT
Dayton, OB
Pont lac, MI
St. Louis, MO
Tonavanda, HT
Croaset, AR
Bakeirsfleld, CA
Cedar Springs, GA
Billings, MI
Flndlay. OB
Fort Morgan, CO
Caring, HE
Greeley, CO
Loveland, CO
Scott* Bluff, HE
Femandlna Beach, FL
Trona, CA
Hahpeton, ND
San Ardo, CA
Norfolk. VA
Cantonment, FL
San Ardo, CA
Granger. HT
Flue Gas
Handled
(SCFM)
84.000
210,000
67,000
40,000
140,000
8,000
128,000
50,000
50,000
18.000
12,000
12,000
25,000
248,000
446,000
36,000
107,000
64,000
92,000
220,000
72,000
420,000
60,000
65,000
65,000
110,000
25,000
122,000
65,000
201,000
500,000
105,000
182,000
8,000
115,000
366,000
140,000
Haste Diaposa^
# &
Fuel
LS Coal
HS Coal
US Coal
HS Coal
HS Coal
HS Coal
HS Coal
HS Coal
LS Oil
LS Coal
MS Oil
HS Oil
LS Coal
HS Oil
LS Coal
LS Coal
LS Coal
HS Coal
LS Coal
Bark/Oll/Coal
LS Coal
Bark/Oll/Coal
LS Coal
LS Coal
LS Coal
LS Coal
LS Coal
LS Coal
LS Coal
Bark/Oil
Coal/Cake/Oil
LS Coal
HS Oil
LS Coal
Bark/Gas/Oil
MS Oil
HS Oil
Scrubber
Type
Direct Lime
Dual Alkali
Dual Alkali
Dual Alkali
Dual Alkali
Dual Alkali
Dual Alkali
Direct Limestone
Sodium Hydroxide
Haste Caustic
Sodium Hydroxide
Sodium Hydroxide
Haste Caustic
Soda Aah
Soda Ash
Sodium Hydroxide
Sodium Hydroxide
Sodium Hydroxide
Sodium Hydroxide
Haste Caustic
Soda Aah
Haste Caustic
Ammonia Hater
Soda Ash
Ammonia Hater
Ammonia Hater
Ammonia Hater
Ammonia Hater
Ammonia Hater
Sodium Hydroxide
Caustic Brine
Ammonia
Sodium Hydroxide
Sodium Hydroxide
Sodium Hydroxide
Sodium Hydroxide
Soda Ash
System
Mode
SO} + Aah
SO, + Ash
SO, + Ash
SO} + Ash
SO, + Ash
S02 + Ash
SO} + Ash
SO} + Ash
SO} (+ Ash)
SO} + Ash
SO,
SO,
SO} + Ash
SO} (+ Ash)
S02
SO} + Ash '
Alh (+ SO,)
SO}
SO} + Ash
SO} + Ash
SO}
SO} + Ash
SO}
SO} -I- Ash
SO} + Aah
SO} + Ash
SO} + Ash
SO} + Ash
SO} + Ash
SO} + Ash
SO}
SO} + Ash
SO}
SO} -1- Ash •
SO} + Ash
.SO, + Aah
soj
Haste Form
Slurry
Filter Cake
Filter Cake
Filter Cake
Filter Cake
Filter Cake
Filter Cake
Thickened Slurry
Slurry
Slurry
Solution
Solution
Slurry
Slurry
Solution
Slurry
Slurry
Solution
Slurry
Slurry
Solution
Slurry
Solution
Slurry
Slurry
Slurry
Slurry
Slurry
Slurry
Slurry
Solution
Slurry
Solution
Slurry
Slurry
Slurry
Solution
v£
W'tf
X
X
X
X
X
X
X
X
X
X
X
X
(X)
X
X
X
X
X
X
X
X
X
X
X
' *47
if V
X
X
X
(X)
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
'Systems producing sulfur or where scrubber liquors are returned to process for use are not included.
Rotations for both vastewater treatment and ponding (or dry filling) Indicate operation* where solids are removed via settling
(or filtration) and waste liquor is treated and discharge.
Source: Arthur D. Little, Inc.
-------
Table 2.8
Summary of Disposal Practices for Operational FGC Systems
on Utility Boilers as of November 1978
Number of Plant/Plant Capacity
Waste Forn System Type
FGD Waste Only Lime-Based
Limestone-Based
Total
Codisposal Lime-Based
N> Limestone-Based
jL Wet Particulate Scrubbing
vO Total
Stabilized FGD Waste Lime-Based
Limestone-Based
Wet Particulate Scrubbing
Total
TOTALS
Wet Pond
Dry Fill
0/0
2/865
1/1585
5/1685
8/4135
—
0/0
8/4135
Lined
oTo
2/2040
1/50
3/2090
—
0/0
3/2090
Unlined
1/200
1/200
2/960
4/2460
4/1195
10/4615
—
0/0
11/4815
Total
0/0
1/200
1/200
4/1825
7/6085
10/2930
21/10840
0/0
0/0
0/0
0/0
22/11040
Dry Fill
o~7o
1/65
1/180
27245
3/1720
2/730
1/165
6/2615
8/2860
Wet Pond
Lined
1/225
1/225
1/165
T7165
~
0/0
2/390
Unlined
1/140
1/140
3/850
2/950
5/1800
1/1650
1/1650
7/3590
Total
0/0
2/365
2/365
4/915
3/1130
1/165
8/i210
4/3370
2/730
1/165
7/4265
17/6840
TOTALS
0/0.
3/565
3/565
8/2740
10/7215
11/3095
29/13050
4/3370
2/730
1/165
7/4265
39/17880
Source: Arthur D. Little, Inc.
-------
• Of the total number of FGD plant installations and FGD
plant capacity, 60% (23 plants and about 10,900 MW)
utilize wet ponding for ultimate disposal while 40%
(16 plants and about 7,000 MW) use some form of dry
fill.
• Of the FGD systems utilizing ponding, approximately
three-quarters involve unlined ponds, and only about
one-quarter involve lined ponds. (The majority of
systems also prethicken wastes prior to pumping to
the disposal ponds.)
• Of those systems utilizing dry fill, the overwhelming
majority of plants (about 80%) operate dry landfill-type
impoundments, although three plants (20%) are currently
disposing of wastes in surface mines.
• Over 90% of the plants and FGD capacity utilize codisposal
(with or without stabilization).
• There are no operating utility systems involving dry fill
of ash-free FGD wastes (nor is there any industrial-scale
dry fill of ash-free wastes).
• There is no stabilization of FGD wastes in Western plants.
While about 40% of the utility FGD systems currently
utilize some form of dry impoundment, the trend toward dry impoundment
is expected to grow over the near future. In 1979, an additional
7,500 MW of nonrecovery FGD capacity is due to come on line, all of
which will involve S02 control only. Of this total, 6,700 MW will
produce solid wastes, approximately 85% of which involve some form of
dry impoundment. Thus, by the end of 1979, the capacity of nonrecovery
FGD systems involving dry impoundment will grow to 50% of the total
utility FGD capacity.
2.1.4 Field Studies of FGC Waste Disposal
There are now underway eight field-scale test and monitoring programs
of FGC waste disposal. Five more programs are in planning and are
scheduled to begin sometime in 1979, and another is being proposed.
2-20
-------
Table 2.9 lists these field testing programs along with the sponsors,
contractors and the range of waste and disposal modes tested.
It is interesting to note that these programs encompass all types
of FGD wastes as well as all of the basic disposal modes available. Of
particular importance are the full-scale and prototype studies. Most
of these focus on one type of waste or disposal mode.
An upcoming program of significance is the multiple-site test
program planned by EPA. It will involve monitoring more than a dozen
FGC waste disposal sites including a variety of different types of wastes
and disposal modes. This two-year effort is scheduled to begin in late 1979,
The scope of each of the programs listed in Table 2.9 is discussed
briefly below. These studies will be referenced and highlighted through-
out the remainder of this report as they apply to specific issues.
•Of taMr <•*•!•)
«o, felr
M^ tely
•0,01, U_
o/iWB. n,feir u»
*•• Q*» XMAtUW* I
•**>~Hl
tm^m^ OBi
2-21
-------
Table 2.9
Summary of Current Field Testing Programs for FGC Waste Disposal
N3
I
ro
•alia: Statua aa of atonal
Location Utliltr (Plant)*
LAMP DISPOSAL;
Hlnnlot. Pover (H.I. To«|)
Culf Poucc (Seholi)
Coif Povar (Ickolt)
— Vn-— A >. oalo
(CroasvllU)
Loulavllla Gaa t Uactrlc
Louisville Caa t Uoctrlc
TVA (T>»»nf)
OCEM DISPOSAL:
D*—.. i Mir
EPA ci/ua/in. 90, o»ir
CPA lacktal SOj 0»lj
CPA/TTA TVA/iodiCal ID. A
/Aaroapac. foi » Aafc
•Oj oair
.
uOC/IPA/EPIV/ OBI/IUCS fO, t Aak
nntDA/pAsn
DA aVA/ADL §0j t
ID, t Aak
p*ar (ram
TIM Trv*
AlUllaa Art lallata-llch
LteastoM Crcaaai
a»al Alkali fwlflU-Uek
LXaa (TUloaorttc) Inlflta-Uck
U*a (CarkUo) talflto-Uck
Baal Alkali lalflta-tlck
Uaa A 1 ta»ar»»a aaaflto-Uck
Llaastoaa (Porcad Cypaiai
(Xlaatloa)
Uaa (nioa.rt.lc) talflto-Uck
•-T "-T
Haata Ckaractarlaclca
rm Umiil Maoa
•art aea Hlaa
rilur Caa* (aaMaklliiW) atacklaf
mic.aail Uarrr (UaataklllsaO *» *•> ""•••••'
Plltar Oka (ItaalllaW A ""--*•*" — •*) *^ Ia»»«a«a«a«
"U" £** (**ili-<> .,, 1,1 i t
riltar Oka (Itaklllaas' A IkMtaklllaaO l»a»aaaaa«
nitar Caka (MaklllaW) fc( « ia. In inlailll
(Pllt.r Caka )
{Coatrlf«ta Caka Ustablllaa* A laata*lllaa<) Irr la»*»aa>B»t
(iklckaavl llarrr)
Plltar Caka
•aox CMkaftractloD
riltar Caka (ItakllliW)
fn«ea»tratoa Daap
>A-r
TMC Araa
Uctloa of Hlaa
^1-Acra Ana
1-Acra Pit
SO-Acra Uta
aaall Plta/Poaoa
J
I * Pita (<.l acra)
4 Pita/Araa
Ml. 2 Acca
1/2-Acra Poad
•ADL - Artkw D. lattl.
CE - Co*u.tlOB
CIA -
CIC -
DOR - DDparCMBt of barer
EPA - U.S. bviroMMtal Protftcclon Afar
EPtI - llKtilc POVEC Inured lutltet*
1UCS - IU Comraloa
LCI - U>ul««lll« Cu _d Uwtrlc
Aoaarliai
lav Toik Stata aaortr aaaaarca A Bnalof»jaW Aittborlty
PAtBT - Po»n AMkorlcr of tka Stata of lav lot* •
tan - ttata omliaraltr of law tort
TfA - Til Tailor AMkocltr
UL - Oalmriatr of L««1«»11U
•D - Oklviraltr of fcrtb Dakota
-------
2.2 Disposal on Land
At present, all FGC wastes are disposed of on land. There are five
basic modes of land disposal, as noted in Table 2.1, which are considered
as potential options for large-scale disposal operations:
a. Wet ponding
• Conventional wet ponding of coa] ash, FGD wastes and
stabilized FGD wastes as now commonly practiced.
• Gypsum stacking which is not now practiced but which
is being investigated for FGD gypsum.
b. Impoundment of dry or dewatered wastes in managed fills including:
direct impoundment of ash, FGD wastes, combined ash and FGD wastes
(codisposal), and stabilized wastes; and excavation and landfilling
of wastes from interim ponds.
c. Mine disposal
• Surface mine disposal including pit bottom and spoil bank
placement of wastes.
• Underground mine disposal.
Of these five basic options, only three are now being commercially
practiced. There are no stacking or underground mine disposal opera-
tions at present. However, all of these are expected to be practiced
in some form or other in the near future. Table 2.10 summarizes the
five modes and principal variations in terms of commercial practice.
2.2.1 Wet Ponding
2.2.1.1 Conventional Practice
Wet ponding is presently more widely employed than any other method
but is expected to be less widely used in the future. A number of engi-
neering variations are possible in a ponding system. To provide a back-
ground on some pond operations, a brief summary of five ponding operations
is presented in Table 2.11. Schematic diagrams of each of the five ponding
schemes are presented in Figures 2.1 to 2.5.
The implementation of a pond disposal system depends upon the type
of wastes being generated and the manner in which it is handled. In the
case of dry fly ash collection systems, the ash can be either directly
sluiced using a hydrovac system and pumped to the pond, or pneumatically
conveyed to a transfer system where the ash is mixed with sluice water
and pumped to the pond. Bottom ash is usually removed from the bottom
2-23
-------
hO
-e-
Wet Ponding
Conventional
Stacking
Dry Impoundment
Mine Disposal
Surface
Underground
Table 2-10
Summary of Land Disposal of FGC Wastes
Variation
Lined
Unlined
Pit Bottom
Spoil Bank
Wet Waste
Dry Waste
Type of Waste
Ash
X
X
X
X
X
FGD Only Codisposal Stabilized FGC
X X
XX X
X X
X
X
X - Indicates being commercially practiced.
-------
Table 2.11
Typical FGD Waste Disposal Operations - Wet Disposal
Ho.
1
2.
3.
4.
5.
6.
Detail
Company and Location
Plant Size MW
Fuel (average values)
FGC System
Scrubber Reagent
Waste Disposal
Colstrip Plant
Montana Power,
Colstrip, Montana
716
Ash-8.6Z; S-0.77Z
CEA Venturi Scrubber
& Koch Tray + Ab-
sorber Tray.
Alkaline Fly Ash and
Lime.
Settling Pond + Evap-
LaCygne Plant
St.Clair Plant
Sherburne Plant
Reference
oration Pood
[5.9]
Kansas City Power & Light Detroit Edison Northern State Power
Linn County, Kansas Belle River, Michigan Becker, Minnesota
874
Ash-24-25Z; S-5.6I
B&H Venturi + 2-stage
Perforated Tray Absorber
Limestone
Ponding
[10]
325
Ash-4.25Z; S-0.75X
1500
Ash-9Z; S-0.8Z
Peabody-Lurgi Venturi CE Venturi -t- Marble
Scrubber Bed Scrubber
Limestone
Clay-lined Pond
[11]
Alakaline Fly Ash and
Limestone.
Thickening and Perman-
ent Disposal Pond
[5,9]
Bruce Mansfield Plant
Pennsylvania Power
Shipping Port, Penn.
1620
Ash-12.5%; S-4.3Z
Chemico Scrubber &
Absorber System
Lime
Dravo Process Stabili-
zation and Permanent
Disposal Pond
[12,13]
-------
RECYCLE STREAM
SCRUBBER
BLEED
n
EFFLUENT
TANK
FLYASHPOMD
DREDGE
SUPERNATANT
FLVASH CLEAR
WATER POND
SLURRY
SUPERNATANT
SMI
EVAPORATION POND
Source: [9]
Figure 2.1 Waste Handling Colstrip Plant
Montana Power Company
-------
RECYCLE STREAM
tsj
N>
SCRUBBER
PLANT
BLEED
SETTLING
AND
PERMANENT
DISPOSAL
POND
SUPERNATANT RETURN
Source: [9]
Figure 2.2 Waste Handling LaCygne Station
Kansas City Power & Light Company
-------
TO
SCRUBBER
FROM SCRUBBER
AND SPRAY TOWER
LIMESTONE
1
1 SPENT SCRUBBING
(SOLUTIONS
RECIRCULATION
TANK
SLURRY
TANK
1
f
MIX
TANK
POND
WATER
OVERFLOW
SUMP
-\ W
\=^
WASTE DISPOSAL
POND
Source: [11]
Figure 2.3 Waste Handling St. Clair Plant
Detroit Edison Company
2-28
-------
RECYCLE STREAM
SCRUBBER
PLANT
to
I
NJ
BLEED
THICKENER
OVERFLOW
UNDERFLOW
SETTLING
AND
PERMANENT
DISPOSAL
POND
SUPERNATANT
Source: [9]
Figure 2.4 Waste Handling Sherburne Plant
Northern States Power Company
-------
CALCILOX
ADDITIVE
THICKENED
WASTE FROM
FGD SYSTEM
SLURRY
PUMPS
MANIFOLD
MANIFOLD
PIPING
SYSTEM
(7.3 MILES)
SUPERNANT
-, RETURN
I
\=_ RESERVOIR ^:
Source: [12]
Figure 2.5 Waste Handling - Bruce Mansfield Plants -
Pennsylvania Power Company
-------
of the boiler using a sluicing system and pumped separately to a disposal
pond (sometimes a separate pond from that used for fly ash). In the case
of wet scrubbers, wastes from particulate control, SC>2 control, or combined
particulate and 862 control systems, there are two basic approaches. The
wastes can be pumped directly from the scrubber to the disposal pond, or
the wastes can be dewatered first via thickening/clarification prior to
being pumped to the pond. In some wet scrubber systems for S02 control,
the wastes (thickened or unthickened) are first mixed with sluiced ash
or combined with additives for stabilization.
In almost all cases, provision is made for returning supernate to
the process. This is particularly true for ash ponding systems and FGD
systems discharging unthickened wastes directly to ponds. Here, water
management and conservation dictate water reuse. However, not all ponding
systems incorporate water recycle and many which do include this feature
practice only partial recycle. For new systems constructed in the future,
recycle and optimum water management are anticipated to be mandatory.
Wet ponding may be technically employable for a variety of FGC
wastes including stabilized FGD wastes only if two conditions are met:
• A site is available that can be converted into a reservoir
with minimum construction of dams or dikes or excavations.
Otherwise, costs rise rapidly.
• The additive for wet stabilization is available at reasonable
cost. Lime-fly ash stabilization processes cannot be applied
to slurries (only to dewatered FGC wastes). Dravo's process
using Calcilox® additive is the only stabilization
process commercially available for stabilizing slurried
FGC wastes. Such specialized additives may be manufac-
tured at one or few locations. Transportation costs for
the additives beyond a certain distance from point of
manufacture may be high and preclude such stabilization
processes.
Nevertheless, under site specific conditions, these processes can be
applied. In addition to Bruce Mansfield, Allegheny Power System's
2-31
-------
Point Pleasant Plant will employ an analogous Dravo system. This is
likely to be operational in 1979 [14].
An important consideration in pond design is control of leachate
movement. The conventioanl approach is to site ponds in areas where the
underlying soil has low permeability. Dams are constructed of borrow
material of low permeability to minimize seepage. If the wastes were
hazardous and were to be regulated under Section 3004 (which does not
apply to FGC wastes), earthen dikes would be required to be formed of
relatively impervious soil. If the permeability of the wastes and the
underlying soils are not sufficiently low to control seepage to desired
levels, artificial liners or sealants can be employed. This is not common
practice for FGC waste disposal by ponding and may not be required for
stabilized FGD wastes. Where needed, the potential options for liners are;
• Clay sealants like bentonite mixed with granular soils. They
offer superior linings for landfills and ponds because they
provide acceptably low permeabilities and can be expected to
self-seal in the event of a rupture. Their main drawback,
however, is a high transport cost when not available locally.
• Chemical sealants—These are sprayed into the soil in a
landfill or pond in order to plug the interstices. They can
be difficult to apply, but are less expensive than clay
sealants in areas where swelling clays are unavailable.
However, chemical sealant liners are more permeable than
those of clay.
• Synthetic liners—Synthetic liners are the most effective
type available. They can be effective and are easy to install
but puctures can seriously nullify their effectiveness.
Field experience with such liners in large ponds is limited.
• Stabilized FGD wastes, themselves, can be employed as liners.
Two important elements in a ponding system are:
• Design of the pond itself, and
• Design of the pipeline system including interfacing.
These are discussed below.
2-32
-------
Pond Design
Pond design is based on construction of dams or dikes and, in a
few cases, based on excavations in the ground. Ponds can be built
on slopes. Some potential pond designs are illustrated in
Figure 2.6. However, the construction of dikes or other means of
containment for ponds is usually expensive. In the future, particu-
larly if stabilization of FGD wastes is widely practiced, ponding will
probably be limited to those sites that can be converted to a pond with
minimal construction of dams or dikes.
Pipeline Systems
The four principal factors most important to the design of pipeline
systems are:
• Solids settling,
• Erosion/abrasion potential,
• Corrosion potential, and
• Freeze protection.
Of these, avoidance of solids settling in pipelines is usually the
overriding factor in design. Usually, an FGC waste can be conveyed
hydraulically. To prevent settling, conveying velocities usually
range between 1.5 meters and 3.7 meters per second (5-12 ft/sec),
depending on material density, particle size and conveyor pipe con-
figuration [16]. For coarser materials, such as bottom ash and mill
rejects, conveying velocities will be in the higher range, particularly
in vertical pipes such as may be encountered when pumping to elevated
dewatering bins. In long pipelines handling coarse materials, velocities
must be increased above those used for shorter lines. In addition, some
device to create turbulence must be introduced to maintain homogeneous
slurry mix, particularly when conveying bottom ash or mill rejects. Fly
ash slurries with finer particles can be pumped at the lower range of
velocities as can be FGD wastes.
A key parameter in pipeline system design is the percentage of
solids in the slurry. This is determined by the three fundamental
2-33
-------
Side Hill pond
Diked Pond
Incised Pond
Source: [14]
Figure 2.6 Pond designs
-------
physical properties: crystal morphology, particle size, and density of
the waste. System design should emphasize reliability of service and
avoidance of maintenance problems like settling, plugging or solids
buildup in critical parts. FGD wastes and fly ash are often conveyed
at 10% to 25% solids while higher loadings are possible for bottom ash.
The bulk density of the conveyed slurry is usually well below 1.2 gm/cc.
It is also noted that pipeline optimization is only important if
the line exceeds about 1,200 meters (4,000 feet) in length. The usual
practice in short pipelines is to convey the waste as a dilute slurry
and provide adequate redundancy to ensure reliability of service.
Radian [7] reports on distance to disposal site for 54 plants and
concluded that:
• Nearly 93% of all bottom ash and fly ash from the
representative 54 plants is transported less than
8 kilometers (five miles) from the generating plant
to the ultimate disposal site. This is a strong
indication that the cost of transporting large volume
wastes over long distances is generally avoided,
• The mean distance from the plant to disposal sites
was 4.8 kilometers (three miles) for this representa-
tive group of 54 plants and is considered realistic
for the industry as a whole.
2.2.1.2 Gypsum Stacking
FGD processes can produce gypsum either by intentional forced
oxidation or in cases when the sulfur content of the coal is low. In
either case, the special case of wet ponding called "gypsum stacking"
may be applicable even though it is not practiced now. EPRI is
sponsoring a study of gypsum stacking at the Scholz plant of
Gulf Power Company in conjunction with the testing of the prototype
Chiyoda 121 FGD process.
It should be noted that gypsum stacking is common practice in the
phos-acid industry. A brief description of gypsum stacking as it is
practiced in the phos-acid industry [17] is given below to provide
2-35
-------
some insight on how it may be applied to FGD gypsum. However, data
are not available to indicate that phos-gypsum and FGD gypsum are
fully analogous in terms of physical and chemical characteristics.
For example, occluded waste liquor in phos-gypsum is quite acidic
(pH of 2 to 3). FGD gypsum liquor, on the other hand, has a signifi-
cantly higher pH. This factor alone may cause differences in physical
stability of the gypsum in the stacking operation.
The phos-gypsum waste is usually transported as a waste by pipeline
to a pond created by construction of starter dams usually from local
borrow materials. Phos-gypsum as a slurry is discharged by spigotting
into the pond. Gypsum settles rapidly and supernate is piped back to
the process plant and used as makeup water. As the quantity of gypsum
builds up in the pond, the freeboard between pond level and dike top
decreases. When the freeboard between pond level and dike top needs
to be increased, the dike is raised by borrowing material from the
dried surface of the previously deposited gypsum, and the cycle is
repeated. Dredging and dozing are the usual means of achieving the
buildup of the dike. The operation is usually conducted in such a
way that deep trenches are not left along inside edges of embankments.
With this method, each successive dike moves further upstream and is
underlain by the previously deposited gypsum. In some cases, these
dikes permit seepage of contaminated water through them. It is neces-
sary to collect and reimpound seepage, primarily because of the fluoride
present in it. Seepage collection and reimpoundment are facilitated by
construction of a seepage collection ditch around the perimeter of the
gypsum pond, as depicted in Figure 2.7, along with a pump station at the
collection point of the seepage ditch to move the collected seepage water
back into the gypsum pond [18]. Permeability of the dams or dikes can
be minimized by segregation of phos-gypsum fines if needed [19]. Seepage
collection may not be required for FGD gypsum except in site specific cases,
Preliminary indications from EPRl's test program on FGD gypsum
stacking are favorable. Tests are continuing and are expected to be
completed by late 1979 [15].
2-36
-------
SEEPAGE DITCH RETURN
TO GYPSUM POND SY PUMP
.OUTSIDE or
APPROXIMATELY
10 FT WIDE »Y
ABOUT 3 FT DEEP
SURFACE DRAINAGE DITCH EXTERNAL
SEEPAGE T° ™l
SEEPAGE DITCH
Source: [18]
Figure 2.7 Proposed Gypsum Pond Water Seepage Control
System Using a Collection Ditch Around the
Perimeter (EPA Effluent Guidelines Document)
2-37
-------
2.2.1.3 Research Efforts in Ponding
Recent study efforts in this means of disposal have centered on
two issues:
• Most effective means of containing pollutants within the
disposal area; i.e., study of potential liner material, and
• Better definition of leaching from lined and unlined ponds.
Liners for Ponds
Unlined disposal ponds are usually the least expensive method of
waste disposal. This technique, however, has been subject to criticism,
primarily due to the potential for waste contaminants to enter the ground-
water. Nonetheless, many FGD waste disposal systems in operation use
unlined ponding for either intermediate clarifying or ultimate disposal.
The use of unlined ponds for waste disposal is expected to decrease
in the future.
Liners can be of any material including site soils (properly treated)
or materials not native to the site and are used to reduce permeation.
Liners potentially can reduce pollutant mobility and can conserve water
for recycle. At present, the major problem with liners has been high
cost and lack of real time experience under field conditions (i.e.,
questionable longevity).
In principle, the criteria that are important for a liner material
are [20]:
• High strength and elasticity,
• Good weatherability and long life expectancy,
• Resistance to bacterial and fungal attack, and
• Ease of repair.
In addition, the pond design may include a leakage detection system. One
such system consists of underbed drainage channels which collect the leak-
age in a visible sump for periodic observation. Other methods of visible
detection include standpipes and wells. Techniques of measuring ground
resistivity have been Developed and may also be applicable.
2-T
-------
No reliable data are available on the long-term effects of FGC wastes
leachate on disposal site liner materials. The permeability of plastic
liners is claimed to be zero but the durability of such liners in a dis-
posal site for FGC wastes has not been demonstrated. Clay liners would
have more strength, ductility and durability than synthetic liner materials
because of inherent plasticity and buffering capacity, but clays possess
finite permeability. Coefficients of permeability for clay soils usually
range from 10 cm/sec to 10"^ cm/sec, for homogeneous unweathered masses
of normally consolidated clay. Preloading (with formation of cracks),
weathering or inclusion of coarser soil zones (silt lenses, for example)
can produce higher permeabilities in clay masses. FGC wastes tend to be
more permeable than clay soils, but the long-term permeability of fixed
wastes may be as low as that of some clays. Tests on unfixed wastes have
not been reliable in that sample preparation has not been appropriate in
some studies, while in other studies inappropriate testing methods have
— "^ —ft
been used. Permeability test results have varied from 10 cm/sec to 10
cm/sec or lower (10 cm/sec is slightly more than one foot per year) .
Reliable data on wastes permeability are needed.
At present, two important studies are ongoing and may yield useful
results:
a. The U.S. Army Corps of Engineers Waterways Experiment Station
(WES) is conducting a program to: (1) determine the compati-
bility of 18 liner materials with flue gas cleaning (FGC) wastes
and associated liquors and leachates; (2) estimate the length of
life for the liners; and (3) assess the economics involved with
purchase and placement (including disposal area construction)
of various liner materials. The liners that WES is testing
include:
• Admixture types (cement, lime, fly ash),
• Prefabricated liner membranes (polymer, neoprene
coated, etc.), and
• Spray-on types (polyvinyl acetate, latex, asphalt,
cement, etc.).
Results of this investigation are likely to be available in 1979.
2-39
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b. In 1978 EPRI initiated a program to evaluate leachate control
and monitoring systems for solid waste disposal facilities.
The objective is to evaluate liner materials for utility solid
wastes. This 36-month program which will be underway in 1979
may yield substantial technical data on a number of liner
materials.
Leaching from Ponds
The extent of leaching of pollutants from disposal ponds is dependent
on several factors: the hydrostatic head in the pond, which forces per-
colation through the pond bottom; the nature of the waste—primarily the
permeability and the solubility of contaminants it contains; and finally,
the characteristics of the soil beneath the pond. At present, monitoring
wells exist in some of the FGC waste disposal ponds including large ones
like Bruce Mansfield. However, for the better designed systems, adequate
time has not elapsed for meaningful data to be available at present.
Efforts are continuing in this field, and additional insight on field
site leaching is likely to be available in the future.
EPA recently announced [21] that a major project of characterization
and environmental monitoring of full-scale utility disposal sites for
regulation development will be undertaken. This effort will cover
monitoring of about 16 sites to obtain background data and information
to promulgate guidelines or regulations for management of FGC wastes
from coal-fired plants. This 24-month project is expected to be underway
later in 1979.
EPRI is sponsoring a program of monitoring the waste disposal site
at the Conesville plant of Columbus & Southern Ohio Power Company. This
study, which will be underway by late 1979, will be conducted by Michael
Baker, Inc. and Battelle Columbus Laboratories.
The above two studies are expected to provide substantial data on
leaching from ponds and other modes of FGC waste disposal. Proposed
RCRA guidelines [8] provide some guidelines on appropriate impoundment
design.
2-40
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2.2.2 Dry Disposal
2.2.2.1 Description of Practice
Dry disposal methods may involve any one of the following modes:
• Dry collection and direct disposal of coal ash and,
in the future, dry sorbent FGD wastes,
• Interim ponding followed by excavation and landfilling,
• Mechanical dewatering and direct landfilling of FGC wastes,
• Blending with fly ash and direct landfilling of FGD wastes, and
• Stabilization through the use of additives (non-proprietary or
otherwise) prior to landfilling.
Operation of a dry disposal system usually involves up to four
basic steps:
• Collection/storage,
• Processing (dewatering, ash blending, stabilization, etc.),
• Transfer/storage/transport, and
• Placement and compaction.
The exact nature of a particular operation will depend primarily upon
the type of waste and the location of the disposal site. Where disposal
sites are at some distance from the power plant (or waste processing
plant), transport of dry, dewatered, or processed waste is usually
accomplished by open, rear-dump trucks although in at least one case,
a dedicated rail-haul system is being used. Interfacing a trucking
operation with waste production and disposal frequently requires waste
transfer/storage systems, especially at the power plant (or processing
plant). In the simplest cases, this can involve directly filling of
trucks with discharged wastes via feeder chutes or hopper bins (although
provisions for emergency waste storage areas would be required). This
approach frequently is used in dry ash disposal and some codisposal
operations. In some cases, though, particularly for FGD/ash codisposal
and disposal of stabilized wastes, it is necessary to provide interim
storage piles from which the trucks are loaded with front-end loaders.
This usually requires use of stacking conveyors.
2-41
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Where the disposal site is adjacent to the power plant, the trucking
of the wastes can be minimized or possibly eliminated by locating the FGC
waste dewatering or processing plant at the disposal site. Stacking con-
veyors can then be used to move the wastes into the disposal areas and
dozers and earth-moving equipment used to spread and compact the wastes.
This is usually practical only for relatively small disposal operations.
In general, operations at the landfill area involve dumping, spreading
and compaction. Usually, only small sections are worked at any one time.
The wastes are layered in one- to three-foot lifts with spreading and
compaction most commonly accomplished using dozers. In some cases, fly
ash (and bottom ash) and FGD waste can be codisposed without prior
blending. In such operations, the ash and FGD wastes would be placed
in alternate layers.
Dry Disposal of Ash
Coal ash (fly ash and, if necessary, bottom ash although the latter
practice is not common) can be handled in a dry state. In such cases,
the ash is conveyed pneumatically from the electrostatic precipitator
or bag filter to storage silos for intermittent transfer for disposal.
Storage silos may be of carbon steel or hollow concrete stave
construction. Flat bottom silos are equipped with aeration stones or
slides to fluidize dust and induce flow to the discharge outlets. Motor
driven blowers supply the fluidizing air. Heaters may be required to
prevent moisture from forming in the silo. Silos are provided with bag
vent filters to prevent the discharge of dust along with displaced air
as the silo is being filled. Alternately, venting can be provided by
a duct from the silo roof back to the precipitator inlet. In some
cases, it may be necessary to install a low pressure blower in the
vent duct to overcome losses which might prevent proper release of
air and cause pressure buildup in the silo or dropout of fly ash in
the duct.
Fly ash normally is deposited in trucks or railroad cars for
transport to a dump area. In such esses, it is necessary to wet the
dust to prevent it from blowing off conveyances during transportation.
2-42
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This is accomplished by means of conditioners which may be
horizontal or vertical rotary pug-mills. These units require water under
pressures of about 80 psi. Alternately, if ash is deposited close to the
plant area, it may be mixed with water at the vacuum producer part of the
handling system.
The wetted coal ash is deposited in the fill site and spread by
dozers in small lifts 0.3 to 1 meter (about 3 feet) and compacted by
wide track dozers or heavy rollers. When and where needed, water
trucks are employed during disposal operations at the site to control
fugitive dust. The lifts are built up to a total ultimate fill height
which will be site specific but which may range from 9 meters (about
30 feet) to over 25 meters (over 82 feet).
In the future, disposal of dry sorbent FGD wastes is expected to
follow analogous operations. Dry sorbent wastes are expected to be
fine, dry solids similar to fly ash (dry sorbent wastes may contain FGD
wastes and fly ash for simultaneous removal will be practiced).
Interim Ponding
In this approach, the FGC waste is settled in storage ponds and
the supernate is recycled to process or otherwise lost through evapor-
ation. The pond may be reclaimed or, when the material is a moist solid,
may be excavated and landfilled in a permanent site. This method has been
used for disposal of sluiced ash from dry collectors and in at least some
cases for disposal of wastes from wet particulate scrubbing systems [6],
The interim ponding/excavation method is most applicable in arid regions;
it will find only limited use for FGC waste disposal in the future.
Examples of interim ponding of FGC wastes are at the Colstrip plant of
Montana Power and the Cholla plant of Arizona Public Service. The Four
Corners plant of Arizona Public Services employs interim ponding for
coal ash.
i
Mechanical Dewatering and Landfilling
Mechanical dewatering methods, including vacuum filtration or
centrifugation, may remove enough water from FGC wastes to allow
direct landfill disposal without additional processing (e.g., ash
2-43
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blending or stabilization. This method of disposal is applicable
to:
• Sluiced fly ash from dry collection systems where the ash
is dewatered in settling/decantation bins,
• FGD wastes from systems producing sulfate-rich wastes,
• FGD wastes from systems employing forced oxidation to
produce gypsum, and
• FGD wastes from dual alkali systems, especially those
employing simultaneous fly ash and SC>2 control (these
wastes are sometimes more readily dewatered than sulfite-
rich wastes from conventional direct lime or limestone
scrubbing systems) [22].
An example of such a system is installed at the Caterpillar Engine
Plant at Mossville, Illinois [9]. In this 56 MW unit burning 2-1/2% S
coal, an FMC dual alkali system employing sodium carbonate/hydrated
lime produces a cake of 50-70% solids in vacuum filters; the cake is
placed directly in a landfill.
Improvements in dewatering behavior and crystal morphology through
control of scrubber operation may make this method more applicable, A
typical generic flowsheet for sulfate-rich (or gypsum) waste is shown
in Figure 2.8.
Blending with Fly Ash
Usually it is difficult and expensive to dewater FGD wastes,
particularly sulfite-rich or mixed sulfate/sulfite wastes. An alter-
native to produce a moist cake suitable for landfilling is to dewater
to some extent and then mix the dewatered waste with fly ash[22,23] or
soil [24] to produce a mixture with lower moisture content than the
dewatered waste alone and which can be more readily handled. A typical
flowsheet of such a blending scheme is shown in Figure 2.9. Care is
required in designing the system, because the addition of fly ash in the
dry form may lower the moisture content below that needed for optimum
compaction in the landfill. The reactivity of the ash also needs to
be considered in system design.
2-44
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NJ
TO
LIMESTONE
GRINDING
AND S02
ABSORPTION
AREAS
FROM S02
ABSORPTION —-»
AREAS
PUMP
THICKENER
OVERFLOW
TANK
PUMP
VACUUM
PUMP
CONVEYOR LQADING p|LE
FILTRATE
RECEIVER
PUMP
Source: [23]
Figure 2.8 Typical Landfill Scheme for Sulfate-Rich or Gypsum Wastes
-------
ro
•c-
TO LIMESTONE
GRINIDNG AND
S02 ABSORPTION
AREAS
FROM SO?
ABSORPTION AREAS
PUMP
THICKENER
OVERFLOW
TANK
BLOWER
RHEUMATIC
CONVEYOR
LIME
STORAGE
SILO
RAKE
PUMP
LOADING PILE
PUMP
Source: [23]
Figure 2.9 Untreated Waste Fly Ash Blending
-------
Some scrubber vendors like Combustion Engineering [25], Research
Cottrell [26], and others are offering assistance in such design and
construction.
Among the systems employing blending with fly ash is the Martins
Lake Station of Texas Utilities (two 795-MW lignite-fired boilers).
In this system, dewatering of the thickener underflow is accomplished
in centrifuges followed by blending with dry fly ash to produce a mixture
that can be handled for disposal. The solids content of the mixture is
85% and permeability is reported to be 10 to 10~° cm/sec. The wastes
are returned via a dedicated rail-haul system to the surface mine for
disposal. At the mine, the wastes are dumped directly from the rail cars
and compacted. As disposal progresses, the rail tracks are moved to
new areas of the mine.
Co-Disposal of Ash and FGD Wastes
In an engineering context, the advantages of co-disposal seem to
outweigh the disadvantages. It may be easier to handle the sludge-ash
mix than to handle (transport, place, compact, etc.) waste or ash alone.
Fill construction would be easier using one material rather than two at
the same site (mixed wastes versus layers of waste between ash) and
using one material in one fill rather than two separate fills, at the
same site or at separate sites. The mix of ash and wastes (sludge)
should be less compressible and stronger than wastes alone, and less
subject to erosion than ash alone. The mix of ash and wastes may be
self-hardening or it may require less fixative in a mixed fill than in
separate fills.
A possible disadvantage could be an increase in permeability (ash-
waste mix versus waste alone) with potential for more infiltration and
leaching. Another disadvantage is that the mix could be more difficult
to transport than is ash alone (but easier than waste alone, at the
same solids content).
Stabilization Additives
In this method of dry disposal, lime and fly ash or other
stabilization additives are added to dewatered wastes prior to
2-47
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disposal. A generic flowsheet of this scheme is shown in Figure 2.10
based on descriptions of the IUCS stabilization process.
In a stabilization process, cementitious additives produce pozzolanic
reactions that result in increased structural integrity in the wastes.
This chemical process continues after placement. Typically, for dry
impoundment type of disposal, the wastes are thickened and dewatered
to a high solids content and blended with fly ash and lime, thus forming
a material with cementitious properties. This material is transported
to the disposal site where it is spread on the ground in 0.3 to 1 meter
(1 foot to 3 foot) lifts and compacted by wide track dozers, heavy
rollers or other equipment. Layering proceeds in 0.3 to 1 meter
lifts in segments of the site. The ultimate height of a disposal fill
is site specific but may be as high as 25 meters (82 feet) or more.
A properly designed and operated dry impoundment system employing
stabilized wastes may enhance the value of the disposal site after
termination or at least permit post operational use.
An example of the application of waste stabilization and dry
impoundment is the system at the Conesville Station of Columbus & Southern
Ohio. The Conesville generating station is a mine-mouth power plant
located on the Muskingum River near Coshocton, Ohio. The power plant
consists of six high sulfur, coal-fired boilers with high efficiency
electrostatic precipitators for particulate control, totaling about
2,000 MW of generating capacity. Two boilers (Units 5 and 6), each with
capacity of about 400 MW, are equipped with direct lime scrubbing systems
for SO control. The FGD systems (by the Mr Correction Division of UOP)
for each boiler consist of two 200-MW TCA (turbulent contact absorber)
scrubbing modules which utilize thiosorbic lime as the scrubbing alkali.
Each pair of scrubber modules has a separate thickener for initial
dewatering of the waste solids. The waste calcium-sulfur salts
thickened to 25-35% solids (35% solids design) are pumped to the
waste processing plant designed by IUCS for further dewatering and
stabilization by admixture with fly ash and lime. The stabilized
wastes are then disposed of in a section of the existing ash pond
2-48
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K>
I
.e-
TO LIMESTONE
GRINIDNG AND
S02 ABSORPTION
AREAS
FROM SOa
ABSORPTION AREAS
PUMP
LOADING PILE
PUMP
Source: Description of the IUCS Stabilization Process [26]
Figure 2.10 FGC Waste Disposal Using a Stabilization Process*
-------
adjacent to the plant. The disposal operation is essentially a dry
impoundment using standard earth-moving equipment. Figure 2.11 shows
an outline of the process. It should be noted that this system incor-
porates essentially 100% redundancy of all major equipment which would
not normally be required for most systems.
2.2.2.2 Engineering Considerations in Dry Disposal
Detailed design of FGC waste treatment and dry disposal operations
is site and system specific. However, some broad engineering considera-
tions are discussed below to aid in defining environmental impact issues.
These considerations are also broadly valid for mine disposal.
Physical Stability
Physical instability is a potential problem for all FGC wastes,
including stabilized wastes. Geometric factors such as height and slope
angle in a waste/ash fill are interrelated; stability depends on the
combination of fill height, slope angle, wastes density, degree of
saturation, effective cohesion, effective angle of shearing resistance,
and behavior during shearing (dilatant versus densifying). For a given
material, safe fill height decreases with increasing slope angle. For
proper design, data are required in which maximum safe fill height is
related to slope angle and soil shearing behavior. Such relationships
have not been developed yet for FGC wastes because adequate data from
proper tests (triaxial compression tests on consolidated samples with
measurement of porewater pressures) have not been available.
Underlying materials may lead to instability of a waste deposit if
the stresses in those matirials exceed the strength of the materials
under those loading conditions; i.e. , failure may occur because of the
weakness of the underlying strata (a. basal failure in geotechnical
terminology). Weak compressible soils would be potential problem
materials in this context (e.g., normally consolidated clays).
Erosion of cover materials could be important. If a relatively
tight (low permeability) cover soil or seal layer were removed through
erosion and if more pervious wastes we exposed by this erosion, infil-
tration of precipitation or surface runoii into the wastes deposit could
2-50
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50TPH PNEUMATIC
Ni
I
TO POND
TO SCRUBBER
FILTERS
f
TER
*
FILTER
TO
POND
800GPM
FILTRATE
800-
8000
PPH
LIME TRUCK
UNLOADING
STATION
KEY
— CONVEYOR
— PIPE
• SCREW FEEDER
G-GALLON
T-SHORT TON
TO STACKERS
Source: Arthur D. Little, Inc.
Figure 2.11 Schematic of IUCS "Stabilization" Process at Conesville
-------
be increased. Increased infiltration could lead to saturation of wastes
previously unsaturated and could cause generation of significant porewater
pressures. Saturation would increase the weight of the wastes and pore-
water pressure generation would decrease effective stress thus decreasing
the strength of the wastes deposit. Both factors tend to lead to sliding/
slumping. In any case, erosion of cover materials has been studied
extensively and is a function of material credibility, which depends
principally on particle sizes, particle shape and interparticle cohesion.
On the other hand, placement of cover material over a wastes deposit
may cause a mass failure if the added load (surcharge) exceeds the bearing
capacity of the filled material. This could occur with surcharge on a
wastes slope or with concentrated loads due to inequalities in surcharge
loading.
Compaction
Instability problems may be ameliorated by compaction since compaction
may produce several changes: voids may be eliminated (between chunks, not
between individual particles); wastes density may be increased; particles
moved closer together may be bonded more effectively in stabilization
reactions; and effective stress and residual total stress levels may be
increased. If the wastes resemble sandy soils, an increase in density
during compaction may create an important increase in angle of shearing
resistance. Compressibility also would be decreased by an increase in
density. Compaction of natural soils tends to create suction in the water
between soil particles if the soil is unsaturated and tends to swell after
removal of the compaction pressure. This effect probably would not be as
important for sand-like wastes (e.g., some sulfate-rich wastes) as for
more fine-grained platy-particle wastes. The increase in density would
probably yield greater strength since the fine-grained wastes would be
changed in shearing behavior to more dilatant behavior. Saturation of
unsaturated compacted wastes would eliminate the beneficial suction in
the porewater and decrease the strength of the wastes, but the benefit
of increased density could be significant.
2-52
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Physical factors such as compaction effects also may alter with time.
If the wastes are saturated, with low solids content, consolidation may
occur with significant increase in solids content, stiffness and strength;
this may be significant for thickener underflow consistencies. Increase
in density (and consequent increase in strength) created by compaction
should not disappear, but long-term saturation can potentially dissipate
suction effects (and consequent increase in strength) created during com-
paction. Dissipation of suction effects would have most effect near the
surface of a waste deposit because, at depth, overburden pressures could
create interparticle stresses equal to the interparticle stresses created
by suction in the porewater.
The stability of settled sulfite wastes under compaction equipment
will vary with the solids content of the wastes (assuming no chemical
stabilization of wastes) and probably with the type of compaction equip-
ment (static, rubber-tired, steel roller, sheepsfoot, vibratory, etc.).
Experience at the Scholz plant indicated it was necessary to dewater
waste to 70-75% solids content before compaction could be accomplished.
Sulfite wastes tested to date may be incapable of supporting compaction
equipment of any kind unless such high solids contents are achieved first.
Liquefaction may be a more serious threat in sulfate wastes, especially
under vibratory loading. Field tests are required for an answer to
this question.
2.2.2.3 Climate
Climate could affect the stability of a wastes deposit in several
ways. The total amount of rainfall and the intensity of rainfall both
affect surface erosion, but these factors influence the rate of erosion;
i.e., erodible materials will erode if wind and rain :act on them but in-
crease in amount/duration and intensity of wind and rain will increase
the rate of surface erosion. Of course, as mentioned above, infiltration
of water into wastes deposits can lead to saturation, decrease in apparent
strength, and, possibly, to failure. This would be most likely to occur
with wastes of highest permeability in an unsaturated condition, but it
could occur in any improperly designed FGC waste deposit.
2-53
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Freeze-thaw cycles could have several effects. Stabilization reactions
could be retarded, disrupted or destroyed by an episode of freezing soon
after mixing and placement. Freezing could produce cracks in the near-
surface layers of a wastes deposit (frost polygon behavior). Cracks in
the wastes deposit could yield greater mass permeability and infiltration
rate even though waste blocks between cracks had been compressed and even
dewatered. In a fill created in layers over a number of years, freeze-
thaw effects on temporarily exposed faces and surfaces could produce
horizontal layers through the finished deposit, with high "crack" per-
meability in such layers (this type of structure is common in masses of
alluvium along large rivers). Increased permeability could lead to more
formation of leachate. On the other hand, freeze-thaw cycles, may be
effective at some sites in dewatering surface layers. The problems of
crack formation could be ameliorated by compaction of the thawed material
after maximum possible evaporative dewatering and before placement of
additional thickness of wastes. Freeze-thaw effects require investigation.
2.2.2.4 System Design and Post-closure Land Use
Often it is difficult to specify the ultimate use of the land on
which FGC waste disposal is planned or practiced. However, it is impor-
tant to recognize engineering constraints on post-closure land use. Post-
closure land use would tend to be limited by nature of the loads created
or by the sensitive nature of the structures or facilities built on the
wastes fill. For example, placement of some sort of fill in a uniform
layer over the entire waste deposit should be feasible, but imposition
of concentrated loads (e.g., footings in a building) may cause bearing
failure with rapid plunging of the loaded element into the wastes. Vibra-
tory loads as from machinery foundations could have disastrous effects on
unfixed wastes. The rate of application of load also is extremely impor-
tant—loads applied slowly may allow consolidation of the wastes during
loading, yielding higher strength than for material loaded rapidly.
Rapid application of load increases shearing stresses and may decrease
shearing resistance if the structure of -the wastes is disturbed (collapse
or remolding).
2-54
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The nature of the supported use also is important. A park built on
cover soil over FGC wastes would not be affected seriously by wastes
settlement. A low, flexible structure like a warehouse would e:;ert low
loads and could tolerate greater total and differential settlements than
could a structure like a boiler-turbine-generator complex.
Uses of adjacent land could be restricted by access or geometry
limitations (e.g., difficulty in building access roads across wastes
deposits) or by consideration of possible failure of wastes retention
structure, or by pollution effects (losing the use of groundwater through
pollution by leachate from FGC wastes).
In the choice of a site for disposal, it is well to note that any
land could be used for wastes disposal, with proper engineering design,
but the choice to dispose of FGC wastes at a given site might be based
on the concept of "best and highest sequential use" with all technical,
economic and environmental factors considered. Obviously, waste land
areas with irregular topography (for ease of containment and a source of
cover soil) and highly impervious subsoils would be ideal. Valuable,
flat or uniformly sloping areas with highly pervious soils and scarce,
pure (thus valuable) groundwater would be poor locations for disposal
sites. Wetlands would be a poor choice.
Runoff-Related Considerations
To limit water losses by runoff from a wastes deposit, grading and
drainage during construction could be employed as in any other construc-
tion activity. After completion of the deposit, a cover soil is chosen
to limit infiltration; a soil consisting of a mixture of clay, silt and
sand fractions is better for this purpose than a material of uniform
grain size, no matter what the average grain size. Water recycle could
certainly be employed; surface runoff caught in temporary retention basins
could be piped back to the FGC system.
To limit water losses by leachate, water infiltration into the fill
is minimized by the techniques mentioned above, the water content of the
wastes is minimized by dewatering prior to placement and a seal layer is
prepared in the bottom of the fill area prior to wastes placement. Below
2-55
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the bottom seal, a pervious drainage layer could be constructed to surround
the wastes deposit; this pervious layer would collect leachate and carry
it to a central sump. From the sump, the leachate could be recycled to
the scrubber (if feasible) or it could be sprayed on the surface of the
fill to utilize evaporation as a means to decrease leachate quantity, or
it could be piped to a treatment plant. If the natural subsoils at the
disposal site were very pervious, a seal layer could be required below the
drainage layer.
2.2.2.5 Design of Landfill
Landfill design can be based on many configurations. Three broad
generic configurations are shown in Figure 2.12. Some pertinent comments
are:
• The structurally simplest form of landfill which may be
utilized with level terrain is the heaped landfill. Even
though this design is simplest in terms of site preparation
and may offer advantages in terms of slope stability and
groundwater pollution, it is often aesthetically undesirable.
• Side hill design is advantageous and often utilized in
areas of hilly terrain where the natural slope of one
side of a hill or valley may provide containment. The
side hill landfill must be prepared properly to ensure
stability.
• The valley fill design, which is the most common type of
landfill used, is often the most complex in terms of
original site preparation. Natural valleys or ravines
are often sources of surface water runoff and may have
springs along side slopes. In such cases, surface water
and groundwater control is usually necessary to avoid
accumulation of water and the development of a leachate
problem. Drainage must be provided and, in some cases,
hydrologic modifications to divert water flow around
the landfill are necessary.
2-56
-------
Side Hill Landfill
Heaped Lardfill
Configuration
^^^^
Valley Fill
Disposal
Configuration
.v«.<<*W«.&J3 'i&ISETOTSS?
Source: [7]
Figure 2.12 General Landfill Designs
2-57
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Design of a managed operation like a landfill requires adequate
data on the engineering properties of the waste and of the soils at
the site. Laboratory tests give indications of the shearing behavior,
strength and compressibility of wastes. To maximize stability, the
factor of safety is normally set between 1.0 and 3.0, with the value
chosen depending on the consequences of failure. Then, using appro-
priate values of shear strength parameters obtained in laboratory tests,
the designer would obtain combinations of fill height and slope angle
corresponding to the selected factor of safety. The steeper the slope
angle, the lower the maximum safe fill height. No absolute maxima or -
minima exist. Also, underlying strata properties and topography influence
this analysis. Disposal techniques influence stresses, porewater pressures
and shear strength parameters. A proper design is necessarily site specific
Proper landfill design requires control of both leachate movement and run-
off. Stabilization processes reduce permeability of the waste. To achieve
full environmental benefits from such processing and compaction of the
wastes, proper design of the landfill to control runoff is necessary.
Conventional runoff control practice in the construction industry con-
sists of retaining runoff in temporary retention basins to settle sus-
pended solids prior to discharge or other use.
For a brief overview of the data base on land disposal of FGC
wastes, the reader is referred to [28],
2-58
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2.2.3 Mine Disposal of FGC Wastes
2.2.3.1 Introduction
While mines have been used for the disposal of coal ash and mine
tailings for many years, they are only now being seriously considered for
the disposal of FGC wastes. There are currently over 15,000 mines through-
out the United States which together produce over 0.5 billion tons of
coal and 2.5 billion tons of metallic and nonmetallic minerals each year.
About one-third of the mines individually produce over 100,000 tons
annually, mines large enough to handle the quantity of FGC wastes pro-
duced by a normal utility boiler. Such mines represent an enormous
capacity for the disposal of these wastes.
However, much of the capacity is clearly not suitable for FGC waste
disposal. The method of mining, for example, can preclude practical waste
disposal operations. Underground mining which employs caving or cut-and-
fill techniques leave little available void for waste disposal. In open-pit
mining, overburden is often removed from the mine area, and the mineral is
mined downward from the surface in benches, or the mining operation may
follow the ore strata downdip from its surface outcrop, which requires
that the area mined be left open for access of haulage vehicles.
The four different categories of mines which appear to provide the
greatest potential for the disposal of large quantities of FGC waste, at
least with regard to the overall technical feasibility are [29]:
• Surface coal mines,
• Underground room-and-pillar coal mines,
• Underground room-and-pillar limestone mines, and
• Underground room-and-pillar lead/zinc mines.
Of the four categories of mines noted above, coal mines, and in
particular interior and western surface area coal mines, are the most
likely candidates for waste disposal. Coal mines offer the greatest
capacity for disposal, and they are frequently tied directly to power
plants. In fact, many new coal-fired power plants are "mine-mouth"
(located adj.acent to the mine within a few miles) and the mine provides
a dedicated coal supply. Since the quantity (volume) of FGC wastes pro-
duced is considerably less than the amount of coal burned, such mines
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usually would have the capacity for disposal throughout the life of the
power plant.
2.2.3.2 Surface Coal Mines
Description of Mining Operations
The conventional method for surface mining of coal is called "strip
mining." Mining practice in strip coal mines mostly involves the use of
draglines and shovels for overburden removal, smaller shovels and front-end
loaders for coal digging, and trucks for coal hauling. In a few cases,
scrapers and bucket wheel excavators are used in softer overburdens.
However, in strip coal mines where the overburden is relatively soft or
can be loosened somewhat by gentle blasting, the dragline is the pre~
ferred machine to use for digging and casting the overburden. If the
formations over the coal seam are hard and compact, and tend to break
into blocky or hard-to-handle aggregates of blocky chunks, then large
shovels are preferred. Now, more than half the surface mining of coal in
the United States involves draglines rather than shovels.
There are basically two different types of strip mining. For
relatively flat or level areas, coal is mined by "area stripping." Area
stripping is commonplace in the Western and Interior coal mining regions.
On steep slopes, the method used is called "contour stripping." Such steep
slope conditions prevail in the Eastern coal region.
A typical area strip mining operation involving the use of a shovel
for removal of the overburden is shown in Figure 2.13. In a typical case
the shovel, sitting on the floor of the pit on top of the unmined coal
removes the overburden and dumps it to the side in the previous cut from
which the coal has been extracted, forming what is called a "spoil bank."
The coal extraction operation then advances behind the shovel. This
may involve blasting prior to digging and loading the coal onto trucks
using smaller shovels and/or front-end loaders.
The area of the spoil banks is reclaimed using dozers, graders, and
standard earth-moving equipment. Reclamation usually involves flattening
of the spoil banks followed by covering with a layer of topsoil and
seeding. The reclamation process usually progresses concurrent with the
mining operation, but at two or three spoil banks removed from the exposed
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NJ
1
CTv
, f
Reclaimed
Area
Stripping Bench -—
Source: [29]
Figure 2.13 Area Strip Mining With Concurrent Reclamation
-------
pit to ensure stability of the spoil banks adjacent to the working areas.
The topsoil used in the reclamation process can either be that originally
present or soil imported from nearby areas (or a combination of both).
The process of removing or obtaining topsoil and storing it adds another
step to the mining operation and must be coordinated with the other
activities. To provide some perspective on strip mines in various
regions, one may note [291:
• Interior surface mines produce 1.5 to 2.0 million tons of
coal annually and seams vary from 0.8 to 2.1 meters (2-1/2
to 7 ft) thick. Width of the pit is often 15 to 30 meters
(50 to 100 ft) while a typical length is 0.6 to 1.2 kilo-
meters (1-2 miles).
• Western surface mines are usually larger. Seams may be
up to 30 meters (100 ft) thick.
Contour strip mining is practiced almost exclusively in the Eastern
region (particularly Appalachia). In conventional contour stripping,
spoil or waste is stripped and dumped downhill from the cut. This
frequently causes water runoff erosion problems with damage to property
holders below. Reclaiming can then be more difficult since waste has
to be moved back up-hill again. A variation in this conventional
approach, known as the "block" ("haulback") method of mining, solves
many of these problems. In the haulback method, spoil is moved
horizontally from the working area to the mined-out cut. This requires
mobile equipment such as bulldozers, scrapers, front-end loaders, and
trucks. The production from individual eastern mines is considerably
less. Eastern surface contour mine production ranges from 0.01 to
1.5 million tons per year. Coal seam thicknesses vary from 0.8 to about
2.1 meters (about 2-1/2 to 7 ft) and are usually horizontal. Contour
stripping method of mining is less amenable to FGC waste disposal than
area stripping method described earlier.
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FGC Waste Placement
In general, inactive surface mines may be less promising
than active mines for FGC waste disposal. Unreclaimed surface mines can
be used for disposal of wastes between remaining spoil banks, and these
may offer suitable sites for disposal. However, because of recent surface
mine reclamation legislation, the number of sites and total capacity
for wastes available in the future may be limited.
In active surface mines, there are basically three options for the
placement of FGC wastes:
• In the working pit, following coal extraction and prior to return
of overburden,
• In the spoil banks, often return of overburden but prior to
reclamation, and
• Mixed with or sandwiched between layers of overburden.
In any disposal operation in an active mine, though, the general over-
riding consideration is that disposal should cause minimal disruption of
mining or reclamation activities. This provides a number of constraints
on the disposal system.
First, the amount (volume) of FGC waste disposed of in any surface mine
should not exceed the amount of coal removed. The objectives of strip
mine reclamation include returning the mined terrain to topographic con-
figurations similar to original terrains, and returning significantly more
waste to a mine than the coal extracted could slow down the mining and
reclamation activities. In most cases, this does not really represent
a constraint, since the wastes returned to the mine will be only those
resulting from the coal removed. The amount of FGC waste generated from
the combustion of coal will be considerably less than the quantity (weight
or volume) of coal removed. Depending upon the type of coal, FGC system,
and emission standards to be met, the volume of total waste (ash plus
calcium-sulfur solids) will vary from less than 10% of the coal burned to
slightly over 50%. With Western coals, which are relatively low in sulfur,
less than 20% is the rule. With higher sulfur Eastern and Interior coals,
the total amount of wastes will typically run 30% or more.
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Second, the physical condition (consistency) of the wastes must be
amenable to ease of handling, transport, and placement using earth-moving
equipment with minimal potential impact of the mining operations. For
pit-bottom disposal this means that the wastes at the time of placement
or immediately thereafter should have as a minimum the consistency of
a soil-like material with little or no liquefaction potential. A slurry-
like material or a waste with a tendency to flow either when placed or
when overburden is dumped on top could present significant operational
problems or unacceptably high costs for containment measures. A little
more leeway exists for disposal in V-notches (between spoil banks); however,
here again, soil-like materials or relatively cohesive materials that are
relatively easily handled and transported will result in the least cost
and minimal disruption of reclamation activites. At the least, the wastes
must be well filtered (55% solids or higher), admixed with dry fly ash,
or treated.
Finally, minimal use should be made of existing mine equipment for
transport and placement of the wastes at the mine. Dedicated equipment
is preferred and, in most cases, mandatory. In almost all scenarios, waste
is most easily placed by truck dumping. The use of coal trucks for this
purpose could lead to unacceptable delays in coal mining operations due
to the additional time for waste loading and discharging (and possibly
cleaning operations). Furthermore, most large mines use large bottom-dump
trucks for coal haulage. These are designed to carry as much as 150 tons
of coal and are usually constructed of aluminum. Not only might some types of
FGC waste corrode the aluminum, but the bottom dumping of wastes would be im-
practical. These trucks are not designed for ease of maneuvering, and operati
them (or any other equipment) on a freshly dumped layer of waste would be diffi
cult at best. The type of truck used for transport and placement will
greatly affect the quantity of waste that can easily be disposed of.
At present there are only two commercial operations involving mine
disposal of FGC wastes in surface coal mines—one at Texas Utilities
Martin Lake Station and the other at Square Butte's Milton R. Young
Station (North Dakota). Both stations fire lignite and involve returning
combined fly ash and calcium-sulfur solids from SC^ removal to the respective
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mines. The operation at the Milton R. Young Power Station is currently
an EPA mine disposal demonstration project. At this Baukol-Noonan
mine, both pit-bottom and spoil bank disposal are being practiced.
Pit-Bottom Disposal
Pit-bottom dumping is probably uhe simplest, least disruptive
method of surface mine disposal. Transpoi • and placement of the wastes
is most easily accomplished using rear-dump trucks. Access to the pit
floors is usually good, since roads are maintained in relatively good
condition for coal mining and hauling equipment. There is also usually
adequate time for waste placement between coal removal and overburden
replacement.
Major potential problems are interference with coal removal in
the working pit due to instability of adjacent spoil banks caused by the
underlying wastes, and the possible congestion in the working pit due to
the two-truck transport systems (one for coal and one for wastes). Most
of these problems are avoidable by control of waste properties and
placement, and proper scheduling of mining and disposal activities.
In some cases, it may be advisable to concentrate the waste dumping on
the side of the pit farthest from the highwall (against the newly created
spoil bank). This will provide an open "buffer" region where no waste
exists when the next cut is taken and the overburden dumped on the waste.
V-Notch or Spoil Bank Disposal
V-notch or spoil bank disposal, as with pit-bottom disposal, would
involve truck dumping and many of the same constraints with regard to
waste characteristics and disposal operations apply. It involves somewhat
more effort than pit-bottom disposal, since roads must be cut into the
spoil banks at the base of the vees to allow access by waste trucks. This
can be relatively easily accomplished in most cases with standard dozers
and road grading equipment.
While it requires more effort, it may also offer some advantages in
that the disposal is less likely to directly impact the coal removal operation.
There is less pit congestion, less potential of creating spoil bank insta-
bility, and generally less stringent scheduling requirements. For these
reasons, spoil bank disposal may often be preferred to pit-bottom disposal.
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Mixing with Overburden
Waste disposal operations can be adapted to allow mixing of the
waste and overburden. This can be accomplished readily in contour strip
mines where haulback methods are used and in some Western mines where
overburden is handled by truck. However, in many strip mines, mixing
waste and. overburden or sandwiching waste between layers of overburden
may require too much additional handling of materials as well as added
constraints on the dragline or shovel operation. Thus, in most mines
this type of operation is not expected to be practical.
Overall Disposal System Implementation
There are many possible disposal system configurations depending
upon the type of waste (filtered waste admixed with fly ash or treated),
distance between the power plant and mine, and the type of placement.
In general, though, the distance between the mine and power plant is the
overriding factor which dictates the amount of handling and the types of
transfer facilities required.
For onsite (mine-mouth) disposal operations, truck transport of
wastes would probably be preferred. In many cases it would be advanta-
geous for the fly ash/filter cake mixing system or waste treatment
operation to be tied directly to the truck transport system to minimize
double handling of material and minimal storage capacity for the wastes.
For offslte mine disposal where the mine is more than a few miles from
the power plant, rail haul of the wastes is a practical and economical
alternative. Either the same train used to carry the coal or a dedicated
smaller train can be used to carry the waste to the mine. If the coal
train is used or if the distance between the power plant and the mine is
such that the turn-around tim^. on a dedicated train is long, then waste
transfer/storage areas at both the mine and the power plant would
probably be required.
2.2.4 Underground Mine Disposal
Underground mine disposal of FGC wastes is not currently practiced.
However, there have been a number of studies evaluating the potential for
underground mine disposal including work by Radian [75] for the U.S. Bureau
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of Mines, a study by Arthur D. Little [29] for the U.S. EPA (IERL), and
a study by Michael Baker Jr., Inc. [76] for the U.S. EPA (MERL). These
indicate that such disposal operations are technically feasible and can
be economically viable as well as environmentally acceptable. In fact,
underground mine disposal may offer potential benefits in terms of sub-
sidence control, fire prevention, and prevention of acid mine drainage.
Description of Mining Operations
There are two basic underground coal mining methods: room and pillar,
and longwall. Underground coal mines are also often classified as slope,
drift, or shaft mines, depending upon the method of access rather than
the mining method used.
Room and pillar mining involves removal of the coal in "rooms"
leaving "pillars" to support the roof. Room and pillar coal extraction
can be "conventional" wherein the coal is extracted in a series of dis-
crete steps (undercutting the coal, drilling, blasting, loading, and
shuttle car haulage to main haulage belts or rails) or "continuous"
where continuous mining machine cuts the coal, loads and delivers it to
shuttle cars (which really makes the system only semi-continuous) or to
conveyor belts for removal from the mine. In most room and pillar systems
another important step is to place roof bolts for supports as the mining
proceeds.
If the pillars are not robbed, the coal extraction is on the order
of 50%. If geologic and roof conditions permit and if surface caving
can be allowed, the pillars can be robbed (removed) as one retreats back
to the access opening, which can increase extraction to 70-80%. Complete
extraction through pillar robbing is not technically feasible.
Longwall mining systems rely on the controlled caving of the roof.
The system consists of a coal cutting machine, chain conveyor system,
and hydraulic movable roof support. The operation of longwall coal
systems is more nearly continuous (when they operate successfully) than
room and pillar mining, with coal cutting, removal, and prop advance
going on steadily. When the props are advanced, the unsupported roof
caves and leaves what is known as gob area.
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Most U.S. coal mines using longwall techniques also produce coal
by room and pillar methods; hence, coal production from any mine is
rarely all from the longwall mining operation itself. Longwall mining
methods (including shortwall mining) cannot be used in all underground
coal mines in the United States. Application of longwall operations
are limited to areas where the surface above can be disturbed and where
the coal to be mined occurs in configurations amenable to the longwall
layout.
FGC Waste Placement
In general, old, inactive underground coal mines offer less promise
than active underground coal mines for FGC waste disposal. Abandoned
mines are often caved and filled with groundwater of unknown flow patterns
caused by the hydrogeologic changes created by mining. The voids are
difficult to find because of prior roof collapse as pillars deteriorate
and fail. Even the initial open cavities prior to roof collapse are
difficult to delineate, as underground mining plans for abandoned mines
are generally not available. Only in a few isolated instances, where
mine conditions are fairly well defined and where disposal of FGC wastes
can be justified as a method for limiting acid mine drainage formation
and/or to prevent further surface subsidence damage does disposal in
abandoned mines appear promising.
Active underground coal mines (disposal in mined-out sections of
active mines), show considerably more technical promise. However, waste
placement would still add complication and additional maneuvering to the
already difficult working conditions. Also, many of the underground mines
utilizing a combination of both conventional room-and-pillar mining with
pillar robbing and/or longwall mining may limit the available capacity
for waste disposal or may require more than one disposal placement technique.
There are basically three approaches that can be or have been employed:
pneumatic backfilling, hydraulic backfilling (or flushing), and mechanical
stowing. These have been demonstrated or practiced in both the United
States and Europe for disposal of mine tailings or placement of fill
materials in underground mines.
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Pneumatic Backfilling
Pneumatic backfilling simply involves blowing the material into the
mine void through a pipeline either from the surface, which enters the
void through boreholes in the roof, or from an underground station mounted
at the entrance to a voided area. Practically speaking, pneumatic back-
filling would have to be done by blind injection, that is, without the
aid of men underground during the backfill operation to direct the flow
of material and control the distribution.
Pneumatic backfilling has been successfully used for the disposal of
fly ash in coal mines, indicating that it may be feasible for use with FGC
wastes. In fact, pneumatic backfilling (stowing) may be the only feasible
method for waste disposal in conjunction with longwall mining operations.
The obvious limitation with regard to FGC waste disposal, though, is that
the material must be dry and free-flowing. Because of the limited experience
0
with pneumatic stowing and the limitations it places on the form of the
waste material, it is not anticipated that pneumatic stowing will gain wide-
spread use for waste disposal.
Hydraulic Backfilling
There has been considerably more experience with hydraulic back-
filling both in the United States and Europe than with pneumatic stowing.
This method has been successfully used to return coarse mine tailings
from both .coal and metal mines to mine voids.
In contrast to pneumatic backfilling, hydraulic backfilling can be
practically accomplished either by controlled or blind injection. The
distribution of material achieved depends upon the pressure head at the
pipeline, the solids content of the slurry, the arrangement of the dis-
charge piping, and the characteristics of the mine void (mine layout, coal
bed slope, etc.). In some cases where there is sufficient slope of the
area being filled, it may not be necessary to install bulkheads to block
out the disposal area to prevent flowing of the material to the active
areas of the mine. However, in most operations utilizing mined-out portions
of an active mine it would have to be assumed that the bulkheading would be
required, particularly where the waste is introduced through the boreholes
in the mine roof.
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In hydraulic backfilling of FGC wastes the solids content of the waste
slurry will vary with the type of waste material. In most cases it is
reasonable to assume that a slurry containing a minimum of 25-30% solids
could be piped into the mine void. With this slurry concentration,
settling in the mine void can be expected, and provisions may need to be
made to pump out water/liquor runoff. If dry wastes are slurried for
hydraulic backfilling (or thickened waste is diluted), then the collected
drainage could be recycled for slurrying the wastes.
A wide variety of wastes can be handled, ranging from simple,
untreated calcium-sulfur solids generated from the removal of SCL to
mixtures of ash and calcium-sulfur wastes or even treated slurried material.
Treated material may offer some advantages in that once stored, in the
mine it will cure and harden, resulting in a relatively hard, monolithic
mass which would be resistent to flow and may also provide a small amount
of subsidence control.
Mechanical Stowing
Mechanical stowing of wastes can be accomplished in active mines
using existing transport/conveyance equipment or equipment that can be
readily adapted for use in the mine. Such operations would generally
not be economically attractive in comparison to hydraulic backfilling;
however, it may be appropriate for use in certain types of mines such
as underground limestone mines where there is ready access to mining
areas. In fact, in limestone mines it may be possible to place wastes
via truckload delivery, since these mines have large, open rooms accessi-
ble from the surface.
Overall System Implementation
Hydraulic backfilling of underground mines is most easily accomplished
at mine-mouth power plants or where the distance between the power plant
and mine is a few miles or less. In such cases, wastes can be piped directly
to the mine and pumped down the mine borehole. Piping of wastes for long
distances, though, can be a problem, particularly if stabilized wastes
are to be used. Thus, this may involve dewatering of the wastes, transport
and reslurrying prior to disposal, all of which would require considerable
rehandling and extra cost.
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Where the power plant is located adjacent to the mine, the wastes
from the scrubber system can be first thickened to 20-35% solids and then
pumped to the mine and down the boreholes. At the mine, drilling of
boreholes and construction of bulkheads across mine voids would be an
ongoing operation to provide new sites for the waste disposal. An interim
storage tank may also be required for the wastes to handle periods of
disposal system interruptions. As the waste materials settle, it will
probably be necessary to also pump out the decanted liquor and return
this to the scrubber system.
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2.3 Ocean Disposal
2.3.1 Overview
Ocean disposal of FGC wastes is not practiced today. However, if it
could be practiced under environmentally satisfactory conditions, it could
represent an important option, particularly in the Northeast where land
for disposal is limited. For this and other reasons, EPA has been study-
ing the disposal of FGC wastes in the ocean [29], At present, regulation
of dispersed ocean dumping of treated and untreated FGC waste falls under
the Marine Protection Research and Sanctuaries Act and is administered by
the Environmental Protection Agency. The dumping would be required to
occur at EPA prescribed dumpsites under the following conditions:
• Mercury, cadmium content of the dumped materials would
be no higher than 50% above that of background sediments
at the dumpsite,
• Concentrates of the dumped material in the water column
four hours after release would not exceed 1% of the 96-
hour LC,-Q of the material to local sensitive species, and
• No feasible alternatives to ocean disposal are available.
Stabilized, brick-like FGC waste may potentially be used to create
artificial fishing reefs with EPA concurrence. Artificial fishing reefs
are not subject to ocean disposal criteria but FGC waste disposal may be
a special case. At any rate, the issue has not been finally decided upon.
While ocean disposal of FGC waste is an option that is perhaps available
to throwaway system users with economic access to the ocean, new ocean dis-
posal initiatives are now discouraged by the regulatory agencies. If cur-
rent studies on ocean disposal of FGC wastes indicate that environmentally
sound disposal is feasible, then the regulatory posture could change.
There are two types of ocean environments for FGC waste disposal:
• Shallow ocean (on the continental shelf), and
• Deep ocean (off shelf).
Each area has a different ecology and may therefore be subject to differ-
ent considerations when evaluating environmental impact. That subject is
discussed further in Section 4.3 of this volume.
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2.3.2 Disposal Technology
Technology for disposal of FGC wastes in the ocean can be broadly
subdivided into:
• Transportation, and
• Surveillance and monitoring.
The former is discussed here, the latter i. Section 5.3.2 of this volume.
Methods for ocean dumping are determined principally by the nature
and form of the waste to be disposed of, and the disposal site in relation
to the site of origin. Consequently, the nature and form of a new waste,
unsuitable for an existing transport system might have to be changed to
make it acceptable for use with the given transport system.
There are currently a number of viable techniques for transporting
waste mixtures to offshore disposal sites. Existing practical technolo-
gies allow either (a) controlled dispersal of the sludge over a great
expanse of water or a sudden total dump; or (b) a continuous pipeline dis-
charge of the sludge. These techniques would fall into the following
categories:
• Self-propelled hopper ship with throttled discharged dis-
posal or with a sudden dump capability,
• Tow-barge transportation and controlled dispersal over a
great expanse of water or a sudden total bottom dump, and
• Submarine pipeline transportation and dispersal at a pre-
selected offshore disposal site.
All these approaches are technically feasible systems which have been
utilized on a full scale for other wastes. Selection among them depends
upon both the characteristics of the waste to be dumped and any environ-
mental conditions and/or constraints that might exist.
Pipeline Transport
For pumpable wastes, this method is mechanically simple. Using an
ocean outfall, FGC waste may be piped many miles to be discharged (usually)
through a section of diffuser conduit several feet above the bottom. Typ-
ical operation is fairly simple, consisting of monitoring and maintenance
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of the pump, pipeline, and diffuser. Depending on operation of the solids
removal process and resulting effluent concentration, active regulation
of pump rate may be necessary. When waste production is small enough to
permit intermittent operation, the outfall may require flushing with
fresh or reclaimed water after each discharge period to prevent sedimen-
tation and possible clogging of the diffuser. Underwater pipeline construc-
tion can be done by bottom pull, floating pipe, and lay barge pipeline
positioning. Lay barge techniques have been used to install underwater
pipelines of 30-inch diameter for distances over 100 miles. In practice,
for design purposes, physical model experiments may be required to deter-
mine critical velocities or appropriate dilutions of the particular sludge.
The costs of offshore pipelines generally vary with length of the
line, depth, pipe size, ocean terrain, and materials to be transported.
The greatest single cost factor in such pipelines is the installation cost,
which generally runs more than 50% of the total investment. Maintenance
is usually the biggest cost factor in the operation of such pipelines.
Surface Craft Transport
The generalized alternative to pipelines lies in carriage of the
material in batches by surface craft to a selected dumpsite. A prerequi-
site for surface release is that the material have a density greater than
water—or in the case of inert or harmless materials, that it be soluble
with a rapid natural rate of dispersion. The vehicle, i.e., the container
for this transport of the material, may be a barge or a self-propelled
craft. The material itself may be in any one of many forms. In general,
economics demand that the material be carried in as concentrated form as
possible and that the transport of large tonnages of water be avoided.
Surface craft adequate fv r offshore disposal purposes exist and are
in use today. Self-propelled hopper-type ships are also currently in use
for waste disposal. The basic configuration of these types of vessels
would resemble the hopper-type dredges owned and operated by the U.S. Army
Corps of Engineers. The capacity of these hopper dredges varies from a
low of 720 cubic yards to a high of 8,277 cubic yards; however, European
dredges are even larger. Better (specially designed) equipment is feasi-
ble. Newer designs may be required to control the rate of release of sludge
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particularly where high dilution factors are required. However, under
almost all conditions, disposal of slurried FGC waste would be economically
impractical. The cost of transporting FGC slurries would be unattractive,
and reslurry of dry or thickened sludge on board large disposal vessels
could require impractically large pumping capacities. A major cost con-
sideration for surface craft involves the necessity to employ two or three
crew shifts if the dumpsite is located outside a round trip range which
can be covered in eight hours or less.
Surface craft can practice one of the following types of dumping:
• Direct release under gravity through the bottom of cargo craft.
• In recent years a new dump concept has appeared in the form of
the clam-shell barge. A. hopper barge is split along a vertical
longitudinal plane and the two symmetrical halves are hinged at
deck level. Buoyancy compartments are arranged so that when the
barge is loaded, control exists to open the joint; when the hopper
is empty, controls can snap the two halves shut.
• In cases where the material is unsuitable or where operating con-
ditions mitigate against the use of large hull openings and joints,
the material must be lifted over the side of the craft and dumped
into the sea. If a deck barge with bulwarks is used, the material
can be shoved overboard through an opening in the bulwarks by
some form of small bulldozer. From a hopper, methods as crude as
the use of a crane and bucket are employed. The latter requires
expenditure of considerable power, use of manpower, and is unsuit-
able in any sort of seaway. Less power and less attendance is
required for pumping the material overboard, but in this case the
material must be liquefied to the extent that a slurry is formed.
Scheduling of ocean disposal can also affect the direction in which
waste materials are being transported, and, hence, environmental impacts.
If the ocean disposal occurs only on the ebb or flood tide, dispersion of
the waste is somewhat restricted to one direction. Generally, one would
try to maximize seaward dispersion.
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To limit the impacts of sludge disposal, the location of dumping has
to be controlled. There are two aspects to such control. The first deals
with navigational accuracy available (or the ability to find any speci-
fied dumpsite with precision). The second deals with policing the opera-
tion to make certain that dumping takes place at the specified location
(within the accuracy limits of the available navigation systems).
Adequate means of navigation are currently available to allow fixing
the location of any particular dump to well within one mile with visual con-
trol and within 0.8 to 5 km (0.5 to 3.0 miles) using navigation aids [29].
2.3.3 Current Studies
At present, the major studies under EPA sponsorship or participation
relating to the ocean disposal of FGD wastes are:
a. The Arthur D. Little/New England Aquarium study [29, 31]
for EPA on the technical, economic and environmental
feasibility of the ocean disposal of stabilized and
unstabilized FGC wastes. This study includes both lab-
oratory and small-scale field testing relating to impact
issues.
b. The State University of New York (SUNY) [32] with funding
provided from Power Authority of the State of New York,
New York ERDA, DOE, EPRI, and EPA, is studying the use of
stabilized brick-like FGC wastes (using IU Conversion
Systems process) to create artificial reefs for marine
habitats. This study is expected to continue for 2 to 5
years.
The preliminary conclusions from the Arthur D. Little/New England
Aquarium study for the EPA are [31]:
• A case-by-case approach to the analysis of the environmental
feasibility of ocean disposal of specific FGC sludges is
needed. The emphasis in each analysis should focus on the
type of sludge and the disposal site environmental condi-
tions.
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Unless further work contradicts observed and anticipated
benthic sedimentation impacts, including mudflows, it
would appear that the disposal of untreated or treated
FGC sludges with soil-like physical properties by bottom-
dump barge or outfall on the continental shelf is environ-
mentally unacceptable.
The problems of disposal of sulfite-rich FGC sludges,
both on and off the continental shelf, appear to be much
greater than those associated with other FGC materials.
There appear to be special grounds for concern over the
potential for oxygen depletion in the vicinity of sulfite-
rich sludge masses. However, sulfite toxicity may be a
relatively minor problem because of the significant rate
of the oxidation reaction.
Disposal options which still appear promising and are
recommended for further research include:
- dispersed disposal of untreated, sulfate-rich FGC
sludges on the continental shelf;
- concentrated disposal of treated, brick-like FGC
sludge on the continental shelf;
dispersed disposal of treated, brick-like FGC sludge
on the continental shelf;
dispersed disposal of untreated, sulfate-rich FGC
sludges in the deep ocean; and
concentrated disposal of both untreated and treated
sulfate-rich FGC sludges in the deep ocean.
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2.4 Disposal Options vs. Potential Environmental Impact Issues
2.4.1 Overview
Environmental impact issues associated with FGC waste disposal
are determined by a mix of four factors:
• Waste characteristics,
• Disposal mode,
• Site, and
• Control measures employed.
The range of options in terms of control measures is sufficiently-
broad that on balance, technology exists for environmental sound disposal
of FGC wastes.
The environmental impact issues requiring consideration in handling
and disposal of FGC wastes are:
• Land-related,
• Water-related,
• Air-related, and
• Biological impacts both in the site and adjacent areas and
consequential effects.
Table 2.1 discussed earlier listed all potential disposal options
for FGC wastes. Table 2.12 lists the issues and mechanisms or factors
causing the impacts. Potential impact issues are highly site- and system-
specific. With that understanding, Table 2.13 illustrates the major types
of impact issues associated with various disposal options. As the matrix
illustrates, the range of waste types and possible disposal conditions
is sufficiently broad to eliminate the potential for "generally significant"
issues to be associated with any of the disposal options. Further, site-
specific application of appropriate control technology can be employed to
mitigate adverse impacts. In other words, issues of potential significance
in FGD waste disposal can best be defined in terms of specific waste types
disposal practices, and disposal environments. The significance of many
potential impact issues needs to be better quantified by additional field-
scale operating experience (and environmental monitoring) with FGC waste
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Table 2.12
Potential FGC Waste Disposal Impact Issues
Impact Area
Air Quality
Impact Issues
Fugitive Particulate Emissions
Gaseous Emissions
(e.g., HS, S0)
Mechanisms/Factors
Handling, Transport, Erosion
Biologic Interactions,
Acid Leaching
Water Quality
Groundwater Contamination
Surface Water Contamination
Leaching
Runoff, Overflows, Leaching
Land Use
Physical Disruption
Land Reclamation/Reuse
Stability
Disposal Mode, Stability
Biota
Habitat Displacement
Bioaccumulat ion/Transfer
Disposal Mode
Water Quality, Direct Uptake
2-79
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Table 2.13
Disposal Options Versus Potential Environmental Impact Issues for FGC Wastes
Potential Environmental Impact Issues
N>
00
O
Disposal Options
Wet Ponding
Dry Disposal
Surface Mine Disposal
Underground Mine Disposal
Shallow Ocean Dumping
Deep Ocean Dumping
Land Use
2
2
2
3
3
3
Surface Water
Quality
2*
2*
2*
3
2*
2*
Groundwater
Duality
2*
2*
2*
2*
3
3
Air
Quality
3
2*
2*
3
3
3
Biological
Impact
2*
2*
2*
2*
2*
2*
X
Significance highly uncertain due to data gaps.
Key: 1 = Issue of potential general significance for all FGC wastes at all disposal sites.
2 = Issue of potential significance for specific types of FGC wastes and/or specific
disposal sites.
3 = Issue of minor or no potential significance.
Source: Arthur D. Little, Inc.
-------
disposal. As indicated in the matrix, this is particularly needed for
defining potential issues in the categories of water quality and
biological impacts.
The remainder of this section provides introductory information on
the general mechanisms of potential environmental impact in each of the
issue categories shown in Table 2.13. The section concludes with a dis-
cussion of the means by which broadly defined issues become specific and
subject to more thorough quantitative and qualitative evaluation for
various FGC waste types, disposal practices, and disposal environments.
Section 4.0 presents results of such evaluations reported as of late 1978.
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2.4.2 Mechanisms of Environmental Impact for FGC Waste Disposal
The chemical and physical properties of FGC wastes (discussed in
detail in Volume 3 of this report) create several mechanisms of poten-
tial impact in each environmental medium (air, water, etc.). These
mechanisms are discussed below under headings corresponding to the various
impact media. This discussion is intended to provide perspective as a
precursor to subsequent sections dealing with specific research programs
and their findings.
2.4.2.1 Land-Related Mechanisms of Impact
This section is divided into two parts, focusing respectively on the
technical (i.e., physical) nature and the public-policy implications of
the impact mechanisms associated with the use of land for FGC waste dis-
posal.
2.4.2.1.1 Technical Nature of Land-Related Impact Mechanisms
The stability of FGC wastes after disposal is a major influcence
on the impact potential of the various disposal options. This is because
physical instability can have adverse impacts on disposal site reuse,
and chemical instability can be a mechanism of contaminant mobilization
in the disposal environment.
Physical instability is a potential problem for all FGC wastes, in-
cluding treated wastes. As discussed in Section 2.2, significant data
gaps exist in engineering information. Three processes that have important
effects on the physical stability of FGC waste material are consolidation,
subsidence, and liquefaction. Secondary considerations (but also
important) are durability and permeability.
• Consolidation is the change in volume of the material caused
by flow of liquid out of pores between solid particles under
a hydraulic gradient created by the weight of the material
itself or by the application of external loads. In fine-
grained materials such volume change and consequent surface
settlement may require months or years to reach completion.
• Subsidence (surface settlement) may be caused by consolida-
tion of waste materials or by loss of basement support (as
might happen in a mine disposal situation). Subsidence may
occur episodically from loss of basement support, but usually
occurs over relatively long time periods (months to years).
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This is in contrast to liquefaction, which can take place
suddenly and without warning.
• Liquefaction can occur in a saturated waste which, like fine-
grained, relatively cohesionless soils, under loading cannot
drain freely; the pore water pressures may increase until the
intergranular stresses are eliminated. The shear resistance is,
therefore, nullified, and the material flows like a liquid.
Such loading may be caused by the vibration of heavy machinery,
including bulldozers, blasting, pile drivers, or earthquakes.
A mass of liquefied FGC wastes would flow very rapidly, possibly at
speeds of tens of feet per second near a failing wastes deposit. Speed
of flow would approach that of water at very low sludge (or mix) solids
contents. Speed would decrease with distance from the failing mass and
with increasing solids content.
Vibrations can also cause excessive subsidence in fine-grained
cohesionless materials (which includes most FGC waste). The frequency of
the vibration is a key determinant in the degree of subsidence. If the
vibration frequency approaches the critical frequency, subsidence may be
20 to 40 times as great as that caused by an equivalent static load.
The greatest amounts of consolidation occur from frequencies in the 10
to 30 Hz impulses per minute range. The problems of susceptibility to
vibrations are limited by two circumstances. The influence of a point
source of vibrations diminishes geometrically with distance. In addi-
tion, properly compacted materials (e.g., compacted with vibratory
rollers at proper moisture content) are not vulnerable to subsequent
vibrations.
The durability of the materials within a filled area is critical
as it relates to the maintenance of structural integrity. Freezing has
been observed to cause fracturing of sludges and subsequent subsidence
due to loss of compressive strength. Freeze-thaw cycles could have
several effects. Fixation reactions could be retarded, disrupted, or
destroyed by an episode of freezing soon after mixing and placement.
Freezing could produce cracks in the near surface layers of a waste
deposit (frost polygon behavior). Cracks in the wastes deposit could
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yield greater mass permeability and infiltration rate even though
waste blocks between cracks had been compressed and even dewatered.
Durability is a waste- and site-specific property which can best
be determined in the field over a length of years through many lab anal-
yses of aged field samples. Mass permeability and infiltration are
important in that increases and decreases in the water content of unsat-
urated materials will alter their properties and thereby alter the
stability of the materials. Thus, the grading of a filled area
(and hence, the extent of infiltration of precipitation) may be critical
to its stability. Increased infiltration could lead to saturation of
wastes previously unsaturated and could cause generation of significant
porewater pressures. Saturation would increase the weight of the wastes,
and porewater pressure generation would decrease effective stress, thus
decreasing the strength of the wastes deposit. Both factors tend to
lead to sliding/slumping. This would be most likely to occur with wastes
of highest permeability in an unsaturated condition, but it could occur
in any FGC waste deposit.
There are various processes which can be used to alter both index
and mechanical properties of FGC wastes. (See Volume 3.) Addition of
chemicals such as lime, silicates, and aluminates can cause a pozzolanic
reaction to occur in fine FGC wastes in the presence of water. Like con-
crete, these pozzolanic materials require a curing period. Other commer-
cial processes have been developed which produce soil-like rather than
concrete-like substances from FGC wastes. The pozzolanic materials, when
properly cured, can be stronger than underlying soils. Soil-like treated
wastes are generally denser, stronger, less compressible, and less per-
meable than many untreated FGC wastes. Thus, the placement of treated
waste is not as environmentally important as that of untreated waste
from a stability standpoint.
Data is lacking on "lifetimes" of fixed wastes. Chemical species
created during fixation may propagate in the field during completion of
initiated reactions; they may be altered or they may be removed. If the
bonding between particles, which was created during fixation, is weakened
or eliminated, instability may result. This is a complex question, e.g.
Portland cement concrete increases in hardness, stiffness, and strength
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for years after mixing and placement if weather and other factors (e.g.,
sulfates in the groundwater) do not cause deterioration.
Physical factors such as compaction effects also may alter with
time. If the wastes are saturated with low solids content, consolidation
may occur with significant increase In solids content, stiffness, and
strength; this may be significant for thickener underflow consistencies.
Increase in density (and consequent increa 2 in "trength) created by
compaction should not disappear, but long-term saturation may dissipate
suction effects (and the increase in strength ilue to suction) croated
during compaction. Dissipation of suction effects would have* most effect
near the surface of a waste deposit because, at depth, overburden pres-
sures continue to create interparticle stresses equal to the interparticle
stresses previously created by suction in the porewater.
Co-disposal of mixtures of ash and sludge (see Section 8.2.2) exhi-
bits impact potentials different than those of independent disposal. It
may be easier to handle the sludge-ash mix than to handle (transport,
place, compact, etc.) sludge or ash alone. The potential air emission
problems of dry ash handling would be eliminated. Fill construction
would be easier using one material rather than two at the same site. The
mix of ash and sludge should be less compressible and stronger than sludge
alone and less subject to erosion than ash alone. The mix of ash and
sludge may be self-hardening or it may require less fixative in a mixed
fill than the materials would in separate fills. A possible disadvantage
could be an increase in permeability (ash-sludge mix vs. sludge alone)
with potential for more infiltration and leaching.
2.4.2.1.2 Land Use Policy Implications of FGC Disposal
Land use impact issues, viewed from the "Public Policy" standpoint,
are focused on three aspects of FGC waste land disposal options:
• Site location,
• Post-closure land use of a disposal site, and
• Impact potential of disposal on adjacent lands.
As the above list indicates, the significance of these issues is
highly site specific. However, they are dealt with in the generic sense
in the discussion below.
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Site Location
The mechanism of impact on public policy in this instance is simi-
lar for FGC wastes and most, if not all, other solid wastes. At the
local level, fulfilling land requirements for solid waste disposal has
become problematic in many areas; either because of a lack of suitable
available land, and/or because of local public resistance to sites
chosen for waste disposal. This situation is reflected in regulations
being developed at both the federal and state levels. A recent draft of
guidelines, generated under the Resource Conservation and Recovery Act
(RCRA) for the development of state solid waste management programs [33] for
non-hazardous wastes, requires that state plans include provisions for
adequate disposal facilities as well as identifying or obtaining the plan
implementation authority. Similar wording can be found in some existing
state solid waste management regulations for approval of county or muni-
cipal solid waste programs. (See Section 3 of this volume.) It is empha-
sized that problems in initial site location, when they exist, would be
location-specific rather than generic to FGC waste types or disposal
practices.
The potential designation of FGC wastes as hazardous or "special" under RPRA
could exacerbate problems with site location due to public sentiment.
Again, these would be location-specific issues. Some current state
regulatory programs address this issue. Under existing California regu-
lation, FGC wastes would apparently be included among "Group I" wastes
requiring disposal in sites that provide maximum protection from leaching
and surface runoff [34]. Oregon's regulations illustrate a different issue-
in that state, hazardous waste facilities must be state owned.
Waste land areai, with irregular topography (for ease of containment
and a source of cover soil) and highly impervious subsoils, would.be ideal
sites for FGC waste disposal. Valuable, flat or uniformly sloping areas
with highly pervious soils and scarce, pure (thus valuable) groundwater
would be poor locations for disposal sites.
The above discussion assumes that open land would have to be found
for a disposal site. Disposal of FGC wastes in operating surface or
underground mines or at abandoned mine sites would not require "new"
land. The regulation of non-coal waste disposal at active mine sites is
2-36
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(as of early 1979), still under consideration by the Office of Surface
Mining due to the Surface Mining Control and Reclamation Act. (See
Section 3.) The use of FGC wastes in abandoned mine reclamation is
discussed further below.
Post-Closure Land Use of Disposal Sites
The present regulatory climate, defined by existing and emerging
regulations, establish post-closure land use of disposal sites as an
impact issue that must be considered:
• Under Federal standards for hazardous waste disposal facilities
[3], land at a closed site must be "amenable to some productive
use." Where wastes remain at a disposal site, certain land
uses are precluded (residential and agricultural, for example).
• Some state solid waste programs already include bonding require-
ments for either solid waste or hazardous waste site operations
to cover site reclamation and even "perpetual care" of sites
where considered necessary. (Examples include: Kansas, 1978;
and Tennessee draft regulations, 1978.) The Kansas Solid Waste
Management Act even includes requirements for a site post-
closure land use plan to accompany the permit application for
non-hazardous wastes. Restrictive covenants can be established,
where deemed necessary, to limit land use or describe mitigating
requirements for closed disposal sites.
• The Surface Mining Reclamation and Control Act requires recla-
mation of mined land, in most situations,to be capable of sup-
porting its pre-mining uses. It also establishes a fund, for
use by states, for abandoned mine reclamation.
Post-closure land use would tend to be limited by the nature of the
loads created or by the sensitive nature of the structures or facilities
built on the waste fill. For example, placement of some sort of fill in
a uniform layer over the entire waste deposit should be feasible, but
imposition of concentrated loads (e.g., footings in a building) may
cause bearing failure with rapid plunging of the loaded element into the
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wastes. Vibratory loads as from machinery foundations could have
adverse effects on unfixed wastes. The rate of application of load also
is extremely important—loads applied slowly may allow consolidation of
the wastes during loading, yielding higher strength than for material
loaded rapidly. Rapid application of load increases shearing stresses
and may decrease shearing resistance if the structure of the wastes is
disturbed (collapse or remolding).
The nature of the supported use also is important. A park built
on cover soil over FGC wastes would not be affected seriously by wastes
settlement. A low, flexible structure like a warehouse would exert low
loads and could tolerate greater total and differential settlements than
could a structure like a boiler-turbine-generator complex.
The various disposal options for FGC wastes present somewhat dif-
ferent potential impact issues relevant to post-closure land use. These
issues are discussed separately below for the various land disposal
options, noting that this is a general, not site-specific discussion.
Dewatered Impoundments and Dry Disposal
For a discussion of post-closure land use impacts, it is assumed
that the final closure procedure for these options would include some
type of soil cover once drying or setting is complete. In addition to
the overall stability of the closed disposal area (discussed in 2.4.2.1.1
above), suitability for post-closure uses could be determined by the
revegetation which may be accomplished, and the extent to which migration
of waste-related contaminants could occur. The latter issue includes
the degree to which the underlying material could reduce vegetation
growth rates and/or result in significant vegetative uptake of trace ele-
ments. Thus, the attentuation capacity of surface and underlying materials
climate regime of the disposal site, as well as the physical and chemical
characteristics of the disposed material are important contributors to
determination of site reuse capabilities. Another question concerning
reuse potential is whether or not there are ameliorative properties of
FGC wastes (or waste components) for certain soil types that would
justify this type of land application. A corollary question is whether
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or not a final soil cover would have to be used to eliminate some trace
contaminant impact potential if food-chain vegetation were to be grown on
a waste/soil mixture.
Mine Disposal
The use of FGC waste in the reclamation of surface or underground mines
would appear to be a potentially satisfacf-ory disposal practice, especially
where used to limit acid mine drainage. Howevtr, disposal in surface mines,
while feasible, is space limited (and hence, time limited) due to the
reclamation requirements of the Surface Mining Control and Reclamation
Act. Disposal in abandoned underground mines appears likely to be
limited in many cases by abandoned mine conditions.
Long-term land use impact issues associated with FGC waste disposal
in surface mines are similar to those associated with landfills, although
the significance of impact may vary due to variations in the depth of
placement of disposal material and disposal techniques. Given SMCRA
reclamation requirements, it is important to address the degree to which
the physical or chemical characteristics of the waste material could
affect post mining reclamation efforts (e.g., the stability and contam-
inant migration issues discussed above). The potential for migration of
contaminants into surface soils would be an issue of greatest concern
for surface mines located in areas of prime farmland.
The existence of an underground mine would appear to be a more
significant issue in limiting post mining surface land use in most cases
than would the additional disposal of FGC waste in the mine. Two notable
exceptions must be considered: (1) the long-term potential (if any) for
S07 emissions in acid mine areas; and (2) future surface stability.
2.4.2.1.3 Impact Potential of Disposal on Adjacent :Land
Mechanisms of offsite land use impacts are essentially similar for
all land-based FGC waste disposal options. Uses of adjacent land could
be restricted by access or geometry limitations (e.g., difficulty in
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building access roads across waste deposits) or by consideration of
possible failure of wastes retention structure, or by pollution effects
(losing the use of groundwater through pollution by leachate from FGC
wastes). The impact mechanisms of principal concern are the potentials
for leachate to enter groundwater systems and for contaminants to enter
surface water. These issues are both discussed in the following section.
These are only indirectly land use issues--insofar as water issues do
have an impact on users (well water contamination, for example). Varia-
tions in the significance of impact would occur for different waste
types, site-specific climatic and hydrogeologic conditions, and disposal
techniques.
The case of very large impoundments built by construction of a dam
may pose an additional issue. This would include the extent to which a
valley watershed serves downstream users and the degree to which the dis-
posal site would affect long-term alterations in surface water conditions
(i.e., quantities and quality).
It is also possible that the nature of adjacent land use could affect
the suitability of some locations for use as FGC waste disposal sites. For
example, if a prospective FGC waste disposal site was immediately down-
gradient of a mining or logging area, removal of vegetation on the adjacent
area could affect erosion rates (and stability of the downgradient FGC
waste site.
2.4.2.2 Water-Related Impact Mechanisms
For many disposal options, the potential for water contamination can
be among the more serious environmental impact issues pertaining to the
disposal of FGC wastes. As .'s true for other potential impact mechanisms
the potential for water contamJnation as a result of FGC waste disposal
is highly site specific and sometin-is waste specific: control measures
required at one site may be unnecessary at another; practices useful in
controlling or preventing water contamination at one site may not be
efficacious at others. Understanding of the mechanisms of surface and/or
groundwater contamination by FGC waste disposal has been limited by the
lack of field-scale disposal and monitoring experience. This constraint
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is still effective today, but increasing requirements for the protection
of water resources have led to a substantial recent expansion in research
efforts. The recent announcement of a large EPA Program [21] and EPRI
Program [15] are expected to fill this gap. This is discussed in Sections
4.2, 4.3 and 4.4 below.
Table 2.14, outlining potential water impact issues, indicates that
some potential for water contamination exists for ocean disposal and
all land-based disposal options, including transportation. However,
as indicated, the probablility of water contamination during transport
is quite low, and no research or regulation of transport of FGC wastes,
with specific emphasis on water, is anticipated.
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Table 2.14
Relative Potential for Water-Related Impacts from Different FGC Waste Disposal Options
Disposal Option
NJ
I
NJ
Waste Type
1 Ash
2. Sulfite Rock
3. Mixed Sulfite/Sulfate
4. Sulfate Rock
5. Stratified Waste
6. Sulfur
Transportation
Low
Low
Low
Low
Low
Low
Ponding
High
High
High
High
Moderate
or NA
NA
Dry Disposal
High to
Moderate
n
n
Moderate
Moderate
Low to
Moderate
Surface
Mine Disposal
High to
Moderate
"
n
"
"
Low to
Moderate
Underground
Mine Disposal
High to
Moderate
"
"
n
"
n
Ocean Disposal
High
"
"
Moderate
Moderate
Moderate
NA • Not applicable
Actual adverse impact potential is mitigated for all options by available
control technology and regulatory requirements for the protection of water
quality.
-------
It is important to remember that this table and discussion are on a
relative basis among disposal options. The potential for negative
impact is compared on a disposal option vs. waste type basis. When con-
sidering the actual characteristics of a disposal operation, that is,
disposal option x waste x site x coi.trol measures implemented, it may be
feasible to reduce or eliminate the actual impact even for option x waste
combinations which have a high generic prcjability of impact.
Unstabilized sulfite-rich sludges are identified as having a high
generic potential for water impact for all disposal options except dry
disposal, which is not considered feasible for such a sludge. Features
of unstabilized sulfite-rich sludges which lead to their relatively high
generic impact potential are:
(a) Their high water content which, through a variety of mechanisms
including physical instability, increases the likelihood of
interaction between the waste and ambient water [35,36],
[37]; and
(b) The relatively high COD of sulfite-rich sludges which can lead
to initial depletion of dissolved oxygen in ambient water when-
ever it interacts with the waste in an agitated medium
[38,39].
Other unstabilized sludge has only slightly lower generic potential
for water impacts than sulfite-rich sludge. Unstabilized sludges by
definition have poorer physical stability, and disposal site management
for control of runoff and leachate is consequently more difficult. Such
practices, as grading to promote runoff and eliminate standing water, thus
reducing leachate generating, are reportedly infeasible for most untreated
FGC sludge [35,36]. Leachates from untreated sludges can exhibit
concentrations of various parameters, including IDS, SO , Chloride, As,
Se, and Hg, in excess of EPA drinking water standards, defining leaching
as an impact mechanism of considerable interest [39.40J,
Several investigators have concluded that stabilization of FGD
sludges by addition of such pozzolanic substances as fly ash, fly ash
and lime, or Calcilox®, will reduce permeability and leachate concen-
trations of TDS and certain major dissolved constituents [35,36].
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Thus, stabilization affects the probability of water contamination as a
result of disposal of FGC wastes. However, some studies report that not
all parameters are reduced in leachate from stabilized FGC materials;
some exhibited increased concentrations [41]. The magnitude of the
reduction in mass of pollutants released, estimated by one report at
1/20 of the pollutant potential of untreated sludge [9] is not so
great as to entirely obviate the potential for water contamination.
Furthermore, as is true for other proposed control measures, evidence
of the effect of stabilization [9] on water impact in field tests
is unavailable at this time. Accordingly, the potential for water con-
tamination by disposal of stabilized sludges is still considered a
realistic mechanism of impact.
Fly ash disposal also presents a significant potential for water
contamination because of the relatively high concentrations of trace
elements sometime found in fly ash leachate. Theis [42] reported
cadmium, lead, and arsenic concentrations in excess (4 to 25X) of EPA
Interim Primary Drinking Water Standards in fly ash and leachate.
Ocean disposal, ponding, and disposal in the surface mine pit
present high generic potential for water contamination because in
each case the waste is likely to be in intimate contact with surface
water and/or groundwater in the saturated zone. The maintenance of water
head in a pond causes percolation into the soil and eventually can
result in elevation of the water table beneath the pond. Lining the
pond is a way to retard or prevent this sequence, but available liners
are generally not perfectly impermeable and are subject to leaking
[43,44].
FGC waste disposal in the working pit of a surface mine followed
by covering with overburden creates a mechanism of potential groundwater
impact because the pit floor is often below the water table. Disposal
in the spoil banks, just prior to reclamation, would generally result in
wastes being placed above the water table with less opportunity for inter-
action with groundwater aquifers. However, infiltration of precipitation
and leachate generation may still lead to water contamination with this
practice. The generic significance of this impact mechanism is considered
similar to that associated with other dry disposal operations.
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Impoundment without maintenance of water cover is considered inter-
mediate in potential for water contamination between ponding and dry
disposal for all stabilized FGC wastes. This reflects the greater initial
water content of the wastes, which are pumped or sluiced to the impound-
ment, in contrast to dry disposal techniques. This greater water content
increases the potential for interaction between ambient surface and ground-
water and the waste. As discussed further in Section 4.2.4, leachate
generation and discharge can be reduced more effectively with dry handling
techniques via disposal site management practices [6,23,24].
Disposal of FGC wastes in underground mines provides mechanisms of
potential positive and negative water impacts [19]. Because they are
often neutral to basic in pH, FGC wastes may serve to mitigate some
instances of acid mine drainage. However, it appears that mechanisms of
potential negative impacts discussed for other disposal options would
also be operative in underground mine disposal. Specifically, leachate
from within the mine, and runoff and/or leachate from any waste-related
waters collected and pumped out of the mine would be mechanisms of
interest.
2.4.2.3 Air-Related Mechanisms of Impact
ponding
Wet ponding involves the disposal of slurries of FGC wastes in ex-
cavated or diked areas. Because the waste is always covered by water,
the only emissions to the ambient air are a result of short-haul trucking,
when it occurs if the material is dry; often wet material is transported.
Most of the dust emissions of native soil from such trucking would consist
of large particles that settle out near the roadside. According to the
Clean Air Act as amended, "fugitive dust emissions" of native soil from
this type of activity are not subject to Prevention of Significant Deteri-
oration permit review. Revegetation or other activities on the pond after
it is filled with waste and water removed (i.e., possible operational
phase) may be subject to fugitive dust. Proper planning can minimize
this impact.
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Dry Disposal
An alternative impoundment procedure is dry disposal wherein the
FGC waste is dewatered to a product having the consistency of moist soil.
Where dewatering occurs at the FGC system site, short-haul trucking and
the use of conveyors are likely means of transport. The waste material
is layered in the disposal basin in six-inch to one-foot lifts and com-
pacted using standard earth moving equipment. Compaction serves the
purpose of preparing a waste surface that is very resistent to weathering
(wind or rain erosion). While the wastes retain at least 5 to 10% mois-
ture, this type of operation does not result in any long-term air quality
impact potential. It is possible that the dewatered and deposited wastes
after drying may be subject to wind erosion at the surface unless control
practices prevent it.
Mine Disposal
As described earlier in Section 2.2.3, in surface mines there are
basically three options for the placement of wastes: (1) in the working
pit, following coal extraction and prior to return of overburden; (2)
in the spoil banks, after return to the overburden but prior to final
reclamation of the land; and (3) mixed with or sandwiched between layers
of overburden. With the exception of option three, each case has the
potential to impact air quality adversely after the waste drier. The
extent of actual emission will depend on whether the wind velocity is
sufficient to transport the particles (generally more than 16 kph or
10 mph) even after the surface is dry and can be subject to wind erosion.
The air quality impact mechanism associated with underground mine
disposal consists mainly of the potential reaction of mine acid drainage
with calcium sulfite in the waste, producing sulfur dioxide gas. This
reaction is expected to occur only in the initial period following dis-
posal because the buffering capacity of the waste would eventually raise
the pH of the mine drainage in immediate contact with it. An additional
possible source of gaseous emissions, over the long term, is microbial
oxidation.
Atmospheric emission of these gases could correspond to drops in
atmospheric pressure, causing the mines to belch gas. This type of
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emission source would be intermittent and of duration only long enough
to allow atmospheric pressure equilibration.
Ocean Pumping
The only adverse air quality impacts associated with this alterna-
tive are due to native soil "shake-up" caused by truck haulage over
dirt roads and/or wind erosion of a dry FGC waste while being transported.
In the former case, regulations exempt the emissions. In the latter,
covering and/or transporting moist material would minimize emissions.
2.4.2.4 Potential Mechanisms of Biological Impact
Mechanisms of potential biological impacts from FGC waste disposal
are derived from disposal and material characteristics discussed above
as mechanisms of potential land-, water-, and air-related impacts. In
other words, if one considers land, water, and air impacts as "primary"
impacts of disposal, then resulting biological impacts might be termed
"secondary." The importance of this concept can be better illustrated
in subsequent sections of the report because it implies that control
technologies applied to mitigate land, water, and air impacts have
the effect of mitigating biological impacts as well.
Mechanisms of potential impact derived from the land impacts of
FGC waste disposal can be described by the phrase "direct habitat modi-
fication." For each of the land-based disposal options discussed in this
report, varying amounts of habitat could be directly modified by the
placement of wastes in ares previously occupied by vegetation and wild-
life. Underground mine disposal has minimal implications from this
standpoint, mostly relating to the transport and interim storage of the
wastes. Disposal in surface mines has this type of impact potential
only insofar as FGC waste substrates might be more or. less supportive of
future revegetation and reoccupation by wildlife than other possible
reclamation substrates. Wet or dry impoundments and landfills create
the most potential for direct terrestrial habitat modification by the
mechanism of devotion of previously undisturbed land to FGC waste dis-
posal. The degree of significance of this type of impact mechanism is,
by definition, highly site specific, since, for example, some of the
devoted land may, in fact, have been greatly disturbed by other activi-
ties prior to its use for FGC waste disposal. (This is true for many
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"captive" sites on utility property.) Over the long term, some land-
based disposal options, upon completion, represent a potentially positive
mechanism of habitat modification impact. This is because revegetation of
these areas can create new habitats that (for a time) add diversity to
their surroundings (e.g., a grassland or early succesional shrub com-
munity within a forest environment).
Conventional; disposal of unstabilized FGC wastes in the ocean has
the potential to substantially modify the suitability of substrates as
habitat for benthic organisms[31]. The mechanism of potential impact in
this instance is replacement of coarse, relatively stable natural sub-
strates with a fine, relatively unstable one. It has been suggested that
certain types of stabilized FGC wastes may create desirable new habitats
(i.e., artificial reefs) when placed in the ocean[32].
Some of the mechanisms of potential biological impact derived from
water-related FGC waste disposal impacts can be referred to as examples
of "indirect habitat modification." Examples include the potential
impacts of increased volumes of dissolved, suspended (and/or settleable)
solids on aquatic biota downstream of supernatant discharges from FGC
waste disposal ponds (wet impoundments). The potential impact mechanism
of sulfite-related oxygen depletion (discussed above in 2.4.2.2) would
have direct and indirect biological impact implications in both ocean
and fresh-water systems. Localized dissolved oxygen reductions in these
systems could directly impact aquatic biota requiring oxygen for respira-
tion and indirectly affect these and other organisms by affecting the
toxicity of other substances in the environment. The release and trans-
port of trace constituents of FGC wastes (especially metals) in aquatic
systems creates two potential impact mechanisms of interest: (1) direct
toxicity to exposed organism^,; and (2) accumulation by exposed organisms
leading to subsequent toxicity elsewhere in the food web. In fresh
waters, leachate and runoff from disposal areas are the precursors to
these potential impact mechanisms. In the ocean, direct discharge would
take place, followed by long-term leaching opportunities.
Mechanisms of potential biological impact derived from air-related
FGC waste disposal impacts appear to be relatively minor in extent.
-------
In theory, the mechanisms described above (Section 2,4,2.3) could create
small zones of increased exposure to particulate and/or gaseous emis-
sions. However, the opportunities for significant increases in exposure
risk seem to be severely limited by the combination of disposal locations
(e.g., deep mines) and contaminants of interest (fugitive particulates),
2.4.3 Issue Definition Process
2.4.3.1 Introduction
In the broadest, most general sense, the environmental issues associ-
ated with FGC waste disposal are defined by the characteristics of the
wastes and the disposal options. This level of issue definition is re-
flected in the general discussion of potential impact mechanisms in
Section 2.4.2 above. Further issue definition (i.e., better identification
of impact potential) is important in the development of a reasonable
strategy for environmental management of these wastes. That is the focus
of the R&D efforts described later in this report (4.0). Specific issues
are defined by the regulations governing FGC waste disposal, usually in
the forms of disposal restrictions, performance criteria, and monitoring
requirements. Therefore, the remainder of this section (2.4.3) provides:
(1) a status summary of the regulatory framework relevent to issues
associated with FGC waste disposal (and discussed in much greater detail
in Section 3 of this volume); and (2) a discussion of a process by which
issues may be prioritized in the evaluation of the results of environmental
assessment studies.
2.4.3.2 Status of Issue Definition by Regulations
A detailed discussion of the status of regulations pertinent to FGC
waste disposal is presented in Section 3 of this volume. This section
is intended to serve as a means of linking the information presented in
Section 3 to the environmental issues discussed throughout Section 2.4.
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Table 2.14 summarizes the present status of issue definition by
regulation of FGC waste disposal. The major point illustrated by the
table is that virtually no specific regulations exist for the sole pur-
pose of governing the disposal of FGC wastes. Such regulations are
either pending development (e.g., under RCRA and the Surface Mining
Reclamation and Control Act) or exist only in the form of more general
restrictions applicable to a variety of waste types. Because of pending
decisions in several areas, the degree to which FGC waste disposal impact
issues are specifically defined by regulations is in a particularly
important state of flux. Pending decisions about the classification of
these wastes under RCRA, and about the procedures for regulating "priority"
or "toxic" pollutants under the Federal Water Pollution Control Act will
help to crystallize the issue definition process when they are made.
In spite of the uncertainties created by the present state of flux
in the regulatory process, another significant point illustrated by
Table 2.14 is that all of the potential environmental impact issues
associated with FGC waste disposal are subject to some form of present
or future Federal regulatory attention. Thus, the environmental assess-
ment and other R&D efforts reviewed in this report can be integrated as
appropriate into the regulatory framework, rather than existing as "paper
studies" in a vacuum.
2.4.3.3 Prioritization of Impact Issues
Given the pending state of regulatory development described above
the authors of this report have had to create certain guidelines for
prioritorization of efforts to report evaluations of potential impact
issues. In general, an effort has been made to give highest priority to
evaluations of potential impact issues associated with well-designed,
well-run FGC waste disposal operations. In other words, wherever possible
attempts have been made to identify separately these types of impacts and
those that might be characteristic of poorly designed and/or poorly run
operations. A third category, consisting of impacts associated with
abnormal events, has also been identified.
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Table 2.15
Status of Issue Definition by Regulations Governing Disposal of FGC Wastes
Res. Cons. Fed. Water Clean Surf. Min. Dam OSHA Marine Prot., Safe Drink. Coal Mine
& Rec. Poll. Control Air Rec. & Con. Safety Res., Sanct. Water Act Health/Safety
Act Act
Physical Stability P
Land Use Policy P
Water Quality P G,P
Air Quality
Biological Impact P G,P
Potentially Appli-
cable Disposal 1,2 1,2,3,4 1,2,3,4 3,4 1 1,2,3, 5 4 3,4
Options 4,5
Key to Descriptions of Status: S » Specific regulations exist for FGC waste disposal.
G - General regulations exist for waste disposal.
P • Further regulations authorized but pending.
Key to Potentially Applicable Disposal Options: 1 - Impoundment
2 - Landfill
3 - Surface Mine
4 - Underground Mine
5 » Ocean Dumping
Vet
G
G
-
G
G
Act Act
G,P G G
G,P
G,P
G
G,P
Act
G
-
G
-
G
Act
G
-
P
G
-
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In the absence of specific regulations, "good design" and "good
practice" are more difficult to characterize, since both are often
practically defined on a site-specific basis by the amount a disposer
needs to (or is willing to) pay. Accordingly, many of the early
environmental assessment studies of FGC waste disposal have failed to
characterize the design or operational efficiency of the operations under
investigation. This introduces many caveats into the review of such
studies presented below in Sections 4.2 and 4.3. Additionally, it
requires that some of the discussion of potential impacts of well-designed
well-run disposal operations appears in Section 4.4, where possible
mitigative control technology for disposal operations is assessed.
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2.5 Site Selection, Design and Practice
Increasingly stringent environmental and economic constraints place
increased emphasis on three aspects of FGC waste disposal:
• Site selection,
• Design, and
• Operational practice.
For new facilities full optimization of each of these is essential. In
this subsection some of the important considerations in each of the
above will be discussed.
2.5.1. Land Disposal
2.5.1.1 Site Selection
Siting of major solid waste disposal facilities like FGC wastes
is drawing substantial regulatory interest. Environmental impact, as
well as engineering/economic factors, must now be assessed. In essence,
the balance between potential environmental impact and costs must be
part of the decision-making process in the selection of an FGC waste
disposal site. Further, the requirements under RCRA and state regu-
lations are baselines that define acceptable environmental standards.
The identification and evaluation of FGC waste disposal facilities is
becoming a major factor in siting new coal-fired utility plants. Many
of the environmental and engineering/economic evaluations conducted in
power plant site selection endeavors are equally applicable to the
siting of FGC waste disposal facilities. Also, much of the technical
and environmental expertise required in power plant siting is also
required to identify and assess solid waste disposal sites. Figure 2.14
presents a logic diagram of an FGC waste site selection process.
The three basic categories of parameters to consider in disposal
and land reclamation site evaluations are regulations, engineering/
economics and environmental. Table 2.16 presents a partial listing of
the categories and their respective parameters. The environmental
evaluation process generically covers the methodology to be employed
to tabulate environmental impacts. In general, the importance of
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STEP1
PROBLEM
DEFINITION
t
w
STEP 2
SITE IDENTIFICATION
fc
w
STEP 3
SUCCESSIVE
SCREENING
^
w
STEP 4
COMPARATIVE
EVALUATION
waste quantities
and composition
• storage volume
available
• environmental
screens
differential costs
• limits of disposal
site search
• minimum acceptance
criteria
• engineering/economic
screens
• environmental
evaluation process
base operating
conditions
identify a number of
sites
reduce sites to a
few best
I
h-«
o
select site
exhibiting best
balance of cost
and environmental
compatibility and
meeting all regula-
tory requirements
regulatory
requirements
MACRO SCALE
CRITERIA
MACRO SCALE
CRITERIA
INCREASING DATA BASE
Source: [100]
Figure 2.14
FGC Disposal Site Selection
Process Logic Diagram
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Table 2.16
FGC Waste Disposal Site Evaluation Parameters
N3
I
Environmental
Air Quality
- dust nuisance
Aesthetics
- visual sensitivity
- natural screening available
Aquatic Ecology/Water Quality
- impact on surface water
- impact on ground water
- sensitivity
- chemical releases via leachate
Land Use
- present
- projected
- proximate
- ultimate
Noise
- sensitive receptors
- natural shielding
- transportation and operation
Public Health and Safety
- fill stability
- transportation disruptions
Socio-Economic
- loss of land productivity
- people affected
- increased value of reclaimed
spoil lands
Terrestrial Ecology
- critical habitat
- threatened or endangered species
- sensitivity of vegetation
Engineering/Economic
Hydrology
- flooding potential
- surface water protection
- ground water protection
Site Development
- surface and subsurface
drainage
- capacity and topography
- fill design
Transportation and Access
- barge
- railroad
- truck
- conveyor (belt or
pneumatic
- pipe
- hauling distance
Geology
- depth of overburden
- ground water depth
- soil types, physical/
chemical characteristics
- need for impermeable liner
Treatment Equipment
- compaction/grading
- leachate
- impermeable liners
Land Availability and Cost
Regulatory
Federal
See Figure 3.1
State
As Applicable
. Local
As applicable
Note:
This is a partial listing and for illustrative purposes only.
-------
environmental parameters relative to each other and the magnitude of the
potential impacts need to be assessed. The Environmental Evaluation
Matrix (EEM) developed by Leopold et al.[101] is one example.
2.5.1.2 Rationale for Good Design/Good Practice
Increasingly severe environmental and economic constraints place
enormous emphasis on planning the operation taking into account all the
constraints. For optimum design/practice of FGC waste disposal,
important considerations are:
a. What environmental impacts could occur and must be mitigated
if possible by design/practice? The principal issues may
include:
• Water-groundwater pollution by leachate; surface water
pollution by runoff and/or leachate; increased water use;
water pollution caused by dike failure or severe flooding.
• Air - fugitive emissions from exposed surfaces of ash
or dry sludge; emission of gases.
• Land - constraint on future land uses; instability
during operation.
• Other - hazards to personnel and equipment.
Impact issues are discussed further in Section 2.4.8 and
Section 4.0. The only emphasis in this subsection is their
importance on design of facilities.
b. Technical/economic consideration to optimize economics and
maximize safety. Basic approach may include:
• Maximization of density - compaction,
• Minimization of 1 indling - co-disposal of ash and sludge,
• Increase of density (solids content) to increase
strength/stability and decrease compressibility,
• Increase of solids content to improve handling properties, and
• Stabilization of mixed wastes with additives to form dikes
and consideration of a lining system, if needed, to contain
wastes and prevent leaching and migration of pollutants.
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The overall objectives of good design/practice are:
• Containment of the wastes, including leachate as much as
practicable. Long term stability of the waste places in
the disposal site is essential.
• Maximization of the amount of wastes/unit volume.
• Minimization of handling problems.
• Facilitation of water recycle as much as practicable.
• Minimization of fugitive emissions.
• Prevention/elimination of operator/equipment hazards.
Several researchers and designers have considered all these in
developing broad approaches. FGD wastes can be broadly categorized into
three types reflecting differences in chemical and engineering proper-
ties. (This is discussed in more detail in Volume 3.) The basic
categories of FGD wastes are:
• Sulfite-rich wastes. The particles are needles, platelets or
agglomerates.
• Mixed sulfate/sulfite wastes. The particles are needles,
platelets or cleavage fragments.
• Sulfate-rich wastes which are needles or cleavage fragments.
Coal ash (fly ash and bottom ash) does exhibit varying character-
istics but not in a manner as to permit analogous characterization. Dry
disposal of ash, co-disposal of ash, and FGD wastes and stabilization
processes for FGD wastes (which usually employs fly ash and lime) are
likely to be widely processed in future. For each of the above cate-
gories, a number of design/practice choices are available. Typical
questions defining the options are:
• Pond wastes or compact in landfill?
• Dewater or mix dry ash with FGD waste for landfilling?
• For dry disposal, lift thickness for compaction?
• Slope angle vs. slope height for dikes/fills?
• Use of stabilization of FGD wastes for containment dikes?
• Material for liner if needed; stabilized wastes, clay, synthetic?
• Thickness of the liner?
• Monitoring methods and degree?
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Some general comments on good design/good practice taking into
account the three categories of FGD wastes and the options defined
above are offered in the remainder of this subsection. These are
broadly applicable but need to be modified in light of site-specific
considerations.
2.5.1.3 Sulfite-Rich Wastes
For sulfite-rich wastes, if co-disposal is indicated, it would
appear to be advisable to convey low-solids sludge to a disposal site
and mix it there with dry fly ash, for a new plant without wet fly ash
transfer facilities. It is not likely that sulfite-rich wastes would
be suitable for landfill except with stabilization; sulfite-rich wastes
are weak, compressible and susceptible to liquefaction under dynamic
loading. Sulfite-rich wastes most likely would be ponded, injected
into deep mines, placed in surface mine pits and spoil banks particu-
larly with stabilization. In the future, placement of FGC wastes in
managed fills is likely to be encouraged. This may require stabilization
of sulfite-rich wastes in many cases.
In any event, sulfite-rich wastes must be contained. In ponds,
this would require use of soil or stabilized wastes in containment
dikes. Use of soil to construct dikes is a common practice and requires
no innovation. Use of FGD waste, FGD waste plus ash or stabilized
waste to construct dikes would require determination of FGD waste and
ash properties (shear strength parameters, compressibility, and permea-
bility as well as compaction behavior). Good design would include
specification of slope angle as a function of proposed slope height
for containment dikes, with the function determined on the basis of
previous laboratory tests. Containment dikes would be constructed in
lifts (layers), with compaction of the lifts to a density specified on
the basis of compaction tests. The dikes would be used to support
deposited wastes but may require a lining to prevent passage of leachate.
Even an embankment built of stabilized sludge would contain cracks and
fissures, so a lining may be required or desirable. The least expensive
lining would be a layer of plastic clay at least 24 inches thick
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compacted at a moisture content well above optimum moisture content as
determined by Standard Proctor test (see Volume 3 for test references).
Placement of the clay on the inside of the dike would ensure that
seeping liquid would carry the clay into any cracks in the dike and
create a seal. Compaction of the wastes themselves would not be possible
unless the sludge (or mix) were dewatered to a solids content of at
least 70% (indicated by tests in 1977-78 at Plant Scholz). This does
not seem to be economically viable for most situations at the present
time. Compaction would be advisable at a plant site if this operation
improved the waste behavior sufficiently to minimize environmental
impacts and/or permit a future use of the site which would return
revenues adequate to defray compaction costs, and the costs of prepa-
ratory dewatering. It is doubtful that increase in density associated
with compaction in and of itself would be cost effective (through
increase in amount of waste placed on each unit of area).
An important design consideration is to insure that FGC wastes
disposed of on land will remain ultimately stable even if inundated by
flooding or other conditions of sustained hydraulic discharge. This is
particularly important if stabilized FGC wastes are employed as diking
or liner materials at the disposal site. Regulations under RCRA on
this issue are under review.
Good.design would include provisions for monitoring groundwater
quality and surface water quality. Current EPA Guidelines [8] on this
issue were relaxed recently and would apply to FGC wastes [8]. Moni-
toring wells could be installed in such a way that if a leak were dis-
covered, the monitor well could be pumped to remove contaminated water.
The area of the disposal site could be graded to cause water to flow to
the locations of the monitor wells. The annular space between the well
casing (perforated) and the natural soil could be filled with sand-
gravel when the temporary hole casing is in place so that a collection
zone was formed around the well pipe. A layer of sand-gravel on the
surface, around the well pipe, could channel leachate to the well; the
site lining would then be placed over the sand-gravel collection zone.
If needed, surface waters could be collected within the disposal site;
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i.e., precipitation falling on the site could be collected by standard
temporary drainage control techniques employed at large-area construction
projects. All contaminated waters would be retained for recycle and/or
treatment.
To facilitate uniform placement of wastes and recycle of super-
natent, a floating boom could be employed. The boom would be moved
daily (or sooner) in a pattern devised prior to construction, to prevent
formation of large delta features. At the present time, it appears
advisable to spread the wastes as thinly as possible to maximize de-
watering by evaporation and/or freezing-thawing cycles. Consideration
should be given to depositing FGD sludge in thin layers between layers
of fly ash; the more pervious fly ash layers would serve as drainage
zones to accelerate dewatering and consolidation of the sludge. Layering
of ash between sludge also may increase the overall stability of the
wastes deposit, but detailed technical and economic evaluation would
be required prior to use of such a technique.
Good design of a waste disposal facility would include planning of
temporary haul roads, usually included via the containment dikes, to
permit equipment access to all reaches of the disposal site.
Also, provisions could be made to use some of the supernatent for
dust control in dry climates where spreading wastes in thin layers over
large areas could lead to fugitive emissions; a moisture content of
only 15-20% should be adequate for dust control. If wastes are placed
in alternating layers (sludge, ash, sludge, ash...) the disposal opera-
tion should be designed so that sludge is placed over ash as soon as
possible; i.e., the time of exposure of unmixed ash should be minimized.
During design of a disposal site, consideration should be given
to designing the placement stquence to meet site-specific needs:
placement on a small area to full depth within a short time to free
that area for another use; or placement of wastes first in those parts
of the disposal site farthest from the plant (source) to reduce the
burden (length of pipelines, pumping pressure, etc.) on aging transport
equipment; or use of land of least value first in hopes that technology
will change (no more scrubbing or sludge of better behavior or dry
wastes...) and more valuable land can be better used; etc.
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Hazards to personnel and equipment would be minimized by placement
of sludge in thin layers, compared to ponding to great depth very rapidly.
Because of the nature of sulfite-rich wastes (weak, compressible,
unstable), a general rule in design would be to use soil, stabilized
wastes or a mix of materials to contain unfixed materials and to rely
on the unfixed wastes to carry no load but rather to impose loads on
containment facilities.
2.5.1.4 Mixed Sulfite/Sulfate Wastes
For mixtures of sulfite/sulfate wastes, it is anticipated that the
sulfite-rich materials will predominate or govern the behavior of the
mixtures in much the same way that silt-sized particles greatly influence
the behavior of silty sands. Obviously, the degree to which the sulfite-
rich wastes influence the behavior of the mixture depends on the sulfite/
sulfate ratio, but a minor fraction (15-20%) of sulfite-rich wastes in
a mixture may virtually govern the permeability, shear strength and
compaction behavior of the mixture (these comments assume that the
sulfate-rich wastes will tend to consist of larger particles of more
equal dimensions as compared to sulfite platelets or needles; if these
assumptions are at variance with the actual conditions at a given site,
the behavior of the wastes at that site may differ drastically from
that suggested here). In a mixture, the smaller and/or weaker particles
will tend to govern behavior. Mixtures of sulfite-sulfate wastes
(assuming the sulfite to be smaller and weaker particles) may closely
resemble pure sulfite-rich wastes in hydraulic properties (dewatering
and permeability) and may be much weaker and more compressible than
pure sulfate-rich wastes.
For these reasons, disposal of mixtures of sulfite/sulfate wastes
may be just as difficult as disposal of sulfite-rich wastes alone.
2.5.1.5 Sulfate-Rich Wastes
Sulfate-rich wastes are usually larger in particle size, with
bulkier, less deformable crystals. Such wastes should dewater suffi-
ciently by gravity drainage, filtration, and/or mixing with dry fly ash
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to permit compaction of the material in self-supporting landfill
configurations. Nevertheless, it may still be necessary to contain
leachate in site-specific instances. Provisions for lining disposal
sites, collecting surface waters on-site, monitoring groundwater quality
and monitoring surface water quality should be considered in an analogous
manner to those employed for disposal of sulfite-rich wastes.
In general, mixing FGD waste with ash may be beneficial for sulfite-
rich materials or mixtures of sulfite/sulfate wastes, but mixing ash
with sulfate-rich wastes may not be advisable unless site-specific
benefits of co-disposal justify such a practice. It may be noted that
ash usually has higher levels of trace metals and hence an environmental
trade-off is involved in co-disposal. That is, the leachate from co-
disposal would often be richer in heavy metals than FGD wastes alone.
2.5.1.6 RCRA and Planning FGC Waste Disposal
The Resource Conservation & Recovery Act of 1976 (RCRA) is the
principal federal legislative framework impacting solid waste disposal
on land. RCRA and other pertinent regulatory framework are discussed
in Section 3. However, some comments on RCRA and FGC waste disposal
design/practice may be pertinent here.
Proposed regulations under the RCRA were issued on December 18,
1978 [8], and are under review. Potentially, these could
undergo significant modifications prior to scheduled promulga-
tion in December 1979. The criteria for identifying hazard-
ous wastes include characteristics such as ignitability,
corrosiveness, reactivity (e.g., strong oxidizing agents), and
certain aspects of toxicity. The protocol for toxicity (which
is the most pertinent to FGC wastes) includes subjecting the
waste to an extraction procedure (EP), followed by chemical
tests for metals and pesticides.
Based on RCRA guidelines published in December 1978, the steps
to determine RCRA related requirements for FGC waste disposal
are:
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a. The proposed Extraction Procedure (EP) specified in Section
3001 protocol will be employed on each FGC waste to deter-
mine if it passes or fails the protocol.
b. If a waste passes the tests, there will be no federal
requirements governing waste disposal under RCRA. However,
guidelines are offered under Section 4004. Individual
states are required to adopt and enforce Section 4004 to
regulate FGC waste disposal if they wish to receive federal
financial aid under Subtitle D of RCRA.
c. If an FGC waste fails the tests, it will be considered a
special waste. Then, only site-selection, monitoring, and
record-keeping standards of Section 3004 (hazardous wastes
disposal) will apply. Design standards under Section 3004
as currently proposed are not required in any case for FGC
waste disposal.
2.5.2 Ocean Disposal
Ocean disposal of FGC wastes is not now practiced. Ongoing studies
and assessment are discussed in Section 2.3. If at a future date ocean
disposal of FGC wastes is practiced, site selection, design and practice
of the waste disposal operation would require considerations analogous
to those discussed for land disposal. Engineering or design approaches
for ocean disposal require further study.
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3.0 REGULATORY CONSIDERATIONS
3.1 Regulatory Framework Overview
FGC wastes are generated when stack gas scrubbing is employed to meet
the requirements of the Clean Air Act as amended in 1977. Once generated,
their transportation, handling, and ultimate disposal may be regulated
under a complex framework of environmental laws and regulations which are
implemented by different offices within an assortment of federal, state,
and local agencies. The implication of the myriad regulations governing
FGC wastes is that removing contaminants from flue gas is not the ultimate
resolution of an environmental problem. Rather, it is the transformation
of the problem into another form which, it is hoped, will be more manageable.
The quantities of FGC wastes which will be generated in the future
depend critically on the implementation of two recent federal laws, the
Clean Air Act of 1977 and the National Energy Act. The National Energy
Act is composed of five separate bills, of which the most significant in
relation to FGC waste generation are the Power Plant and Industrial Fuel
Use Act of 1978 and the Natural Gas Policy Act of 1978.
Implementation and enforcement of the Clean Air Act is expected to
increase the quantities of FGC waste generated by reducing allowable
emissions of particulates and SO for new power plants. The solid waste
impacts of alternative levels of S0_ and control have been considered by
Leo & Rossoff [61]. Existing plants may also be affected by state
implementation plans for TSP and S02. Additional generation of FGC
wastes bv tightening environmental regulations is thus likely. Moreover.
low sulfur coal that now does not require desulfurization may require FGD
systems in the future. Regulations under the Clean Air Act are expected
in mid-1979.
The Power Plant and Industrial Fuel Use Act is expected to increase
the amounts of FGC waste generated by its prohibition of the burning of
oil and gas in new power plants, and by requiring some existing plants
to convert to coal from oil and gas. The Natural Gas Policy Act will tend
to encourage the use of coal and oil by industrial users, by forcing the
greatest burden of natural gas price increases on industrial and utility
users, and by classifying them as lower priority than residential and
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agricultural users In the event of natural gas curtailments. Some users
may convert to alternative fuels in the face of high priced gas with an
uncertain supply. The implementation of NEA has barely begun, and any
assessment of its impact on FGC waste generation is premature at this
time. The provisions of NEA are discussed in Power, October, 1978, pages
68-70. NEA strengthens the coal-conversion-forcing provisions of the
Energy Supply and Environmental Coordination Act of 1974 by transferring
the burden of proof in any coal conversion dispute from government to
industry. Under NEA, a utility must convert to coal unless it can demon-
strate infeasibility. Infeasibility may be based on fuel availability,
site limitations, environmental requirements, state and local requirements
(e.g., building codes), etc.
Most federal environmental law enacted in this decade is implemented
and enforced by the Environmental Protection Agency (EPA). The EPA now
has broad control over all "phases" of the environment: air, water, and
solid wastes. It has been observed, since the passage of the Safe Drink-
ing Water Act, and the Resource Conservation & Recovery Act, that EPA has
authority to protect all phases of the environment in a balanced program
via coordination of regulatory activity affecting several interacting media.
Other branches of government, particularly the Army Corps of Engineers,
the Department of Labor, the Department of Transportation, the Department
of the Interior, state and local governments maintain jurisdiction over
many activities which significantly affect the environment and FGC waste
disposal. In many instances, these separate agencies attempt to coordi-
nate policies and regulations affecting the environment, but organizational
mechanisms for effecting such coordination are absent or poorly defined.
An emerging issue for environmental regulators is the total impact
across all environmental media (air, water, land), and the human environ-
ment—including availability of energy and water, and the social infra-
structure—of regulatory action which specifically addresses a problem
in one environmental "box." For example, does the treatment of water
effluents entail an energy cost, with required generation of that energy
leading to more serious environmental and economic problems? Is S09 in
the air more detrimental to health than FGD sludge leachate and other
scrubber-related effluent streams? Much environmental science, engineering
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and regulation has been developed with an eye to a single environmental
compartment, for numerous reasons, including the maturine of the environ-
mental sciences from media or discipline oriented specialties, and the
topical nature of environmental problems.
Recent environmental laws have different requirements for consideration
of cross-media and environmental impacts with the Clean Air Act having the
least requirements for such considerations. Nonetheless, the laws implicitly,
and in some cases, require consideration of economics, and several provide
mechanisms for consideration of related environmental impacts. A coordina-
ted approach aimed at maximizing the total environmental benefits of a reg-
ulatory program will face technical, institutional, and budgetary constraints.
The technical and budgetary constraints are closely related: it is extremely
difficult to predict the gamut of environmental consequences of a specific
action; consequently, the cost of such an assessment is high. In some
cases, the state of the art is not adequate to predict the consequences,
regardless of cost and of available resources.
Institutional constraints on a cross-media or "global" approach arise
where different departments, agencies, and offices are responsible for
specific environmental "boxes:" air, water, solid waste, mines, waterways,
etc. Since EPA has statutory authority in each of the major "boxes"—
air, water, solid waste—this agency has the greatest opportunity for a
"global" approach, but the establishment of interaction between offices
responsible for the separate media has been reported by some observers to
be a significant bureaucratic problem (Walsh, 1978, Science, V. 202,
p. 600). The research arm of EPA (Office of Research & Development) has
adopted a "global" approach in evaluating total environmental impact on
an industry-by-industry basis with a goal of evaluating the total impact
of specific actions, controls, etc. This base of information has expanded
over the last five years and is gradually being reflected in regulatory
policy. Official mechanisms for incorporating a broad base of cross-media
information to bear on the regulatory process have been slow to develop,
and it is likely that individual initiatives continue to be the most
effective mechanism for coordinating regulatory policy to the end of
minimizing total cross-media environmental impacts.
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Some exemplary provisions of recent environmental legislation which
force a cross-media approach include:
• The requirements of Sections 304 and 306 of the Clean
Water Act (FWPCA) that EPA consider "non-water quality
environmental impact (including energy requirements)"
in the establishing of effluent limitations and new
source performance standards ,
• The requirement of Section 1008 of the Resource Conserva-
tion and Recovery Act that solid waste management guide-
lines provide for the protection of ground and surface
waters and ambient air, and
• The provision of TSCA which directs the Office of Toxic
Substances to consult with other offices within the
agency before formulating regulatory strategy.
It is recognized that in the case of RCRA, the Office of Solid Waste
(OSW), has responsibility for all media - a possible result is that OSW's
air and surface water related standards for disposal sites could be
different from other federal or state standards for the prevention of air/
water pollution from types of facilities. In some instances, this could
potentially create jurisdictional impediments in individual permitting
actions.
Figure 3.1 provides a "cradle-to-grave" schematic of FGC waste gen-
eration, handling, and disposal identifying federal regulatory agencies
with jurisdiction over step processes which involve changes in physical/
chemical properties or location. The right side of the figure presents
the federal regulatory authority with jurisdiction over that process.
Ash and S0» removed from s. Lack gases are not destroyed, but simply
collected and transformed. Based on authority derived from the Clean Air
Act as amended in 1977, EPA is requiring higher levels of control of
particulates and SO-. Based on authority derived from the Federal Water
Pollution Control Act, also administered by EPA, some derivatives of these
wastes may not be discharged in appreciable quantities to navigable surface
waters. Recognizing that only a small fraction of such wastes is put to
beneficial use in the United States, land-based disposal is, indirectly,
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PROCESSES
Waste Generation
at Power Plant
Waste Treatment
(Optional )
Waste Storage
(Optional )
Onsite Disposal
Transportation to
Offsite Disposal
Storage at Site
(Optional)
Landfi11
M i n f; Disposal
n
ACE - Army Corps of Engineers
DOI - Department of Interior '
DOT -^ Department of Transportation
EPA - Environmental Protection Agency
MESA - Mine Enforcement & Safety Administration
OSHA - Occupational Safety & Health Administration
Ocean
Di sposal
REGULATORY
AUTHORITY
EPA, OSHA
EPA, OSHA
EPA, OSHA, ACE
EPA, OSHA, ACE
EPA, OSHA, DOT
EPA, OSHA, ACE
EPA
EPA
EPA, MESA, DOI
EPA, OSHA, DOT
Figure 3.1 FGC Wastes - Federal Regulatory Chart
3-5
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required by the laws mentioned above and administered by EPA (OSHA also has
regulatory authority over issues pertaining to the safety and health of
workers at the generation site, but this authority is tangential to the
issues highlighted here).
Once generated, the wastes may be treated and/or temporarily stored.
FGC waste treatment is not directly regulated or required by law, although
constraints on disposal of sludge encourage, and establish technical stan-
dards for, waste treatment. These constraints on sludge disposal derive
from existing regulations, and speculatively, from anticipated waste dis-
posal regulation.
Temporary storage, whether at the point of generation, disposal or during
interim transport, is regulated in much the same way as disposal discussed below.
Authority to regulate the transportation of wastes rests with the
Department of Transportation, OSHA, and EPA under a variety of laws, and there
is little experience to indicate how presumptions of overlapping authority
might be resolved. One relevant example is in the management of spills of
hazardous materials in the nation's waterways where both EPA and the U. S.
Coast Guard (DOT) have statutory authority: EPA concentrates on identifica-
tion of sources and subsequent legal action, while the Coast Guard performs
emergency response and clean up.
Most viable disposal options are land-based and there are numerous regula-
tory bodies with authority over some phase of land-based disposal. The broad-
est-based authority rests with EPA and particularly with the Office of Solid
Waste which administers the Resource Conservation and Recovery Act of 1976.
The Office of Solid Waste Is responsible for setting guidelines for state solid
waste management plans, efficiency criteria for disposal of non-hazardous waste
and minimum national standards for the handling of hazardous wastes. It is also
responsible for deciding what constitutes a hazardous waste. This decision is
pertinent to the level of control required and the ultimate regulatory authority
over a given waste material: the states are the ultimate authority for the
handling of non-hazardous wastes, while OSW has much more direct control over
hazardous waste management.
EPA also administers the Safe Drinking Water Act (Office of Water Supply)
and the Federal Water Pollution Control Act (Office of Water Programs) which
are significant to land-based disposal of FGC wastes. OWS sets national drinking
water standards and regulates the underground injection of fluids in wells. The
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Office of Water Programs administers the national permitting authority
for point source waste discharges to navigable waters. RCRA authority is
superceded by the Marine Protection Research & Sanctuaries Act, the Hazard-
out Material Transportation Act, FWPCA, and SDWA for all activities and
substances covered by those acts.
It should further be emphasized that the separate states all maintain
varying degrees of authority under all the federal environmental legisla-
tion highlighted above. The states may administer state plans with relative
autonomy (e.g., non-hazardous solid waste management criteria where OSW defines
and prohibits open dumping, writes suggested guidelines and controls allocation
of funds to the states) or, at the other extreme, may administer a state pro-
gram which must be consistent with or more stringent than national standards
set by EPA. Under all the important federal environmental statutes, EPA can
assume certain regulatory authority if the state neglects to implement and
enforce a plan or if the state's actions are inconsistent with the objectives
of the act, as interpreted by EPA.
Other important federal statues which may be used to regulate disposal
of FGC wastes are the Surface Mine Control & Reclamation Act (administered
by the Office of Surface Mining, Department of Interior), the Dam Inspection
Act (administered by the U. S. Army Corps of Engineers), the Federal Coal
Mine Health & Safety Act (Mining Enforcement Safety Administration), the
Occupational Safety & Health Act (Occupational Safety & Health Administration),
and the Hazardous Materials Transportation Act (Department of Transportation).
Of these the Surface Mine Control & Reclamation Act is likely to be
significant, based on the potential for diposal of sludge and ash generated
at mine-mouth power plants, during the reclamation of surface mines. The
authority of the Office of Surface Mining is comprehensive, and the proposed
regulations which have been generated to date are similarly comprehensive.
The OSM/DOI proposed regulations are different from the OSW/EPA regulations
in terms of definitions and regulatory strategy. For example, definition of
"waste" and "toxic" in the OSM/DOI regulations are not equivalent to those in
the OSW/EPA regulations. While OSW/EPA regulations protect "usable aquifers"
from "endangerment" the surface mining regulations require the protection of
"groundwater systems" from changes in flow or quality. SMCRA does not super-
cede FWPCA, or the Clean Air Act. Its relationship to RCRA is not spelled
out in either law, although coal wastes are regulated under MSCRA.
An ultimate or joint authority over FGC waste disposal in surface mines has
3-7
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not been fully established at this writing, making it difficult to assess
the regulatory environment under which waste disposal in surface mines will
occur.
The basis for the discussion to follow is the existing and antici-
pated regulatory environment governing the disposal of flyash and FGD
sludges. However, the discussion of: "Possible future regulations: A
focus on priority pollutants?" suggests a future solid waste disposal
problem. If removal of priority pollutants from waste water streams is
required in future regulations pursuant to the settlement agreement and
the Clean Water Act of 1977, a number of potentially toxic metals initially
cleaned from flue gas will be collected in solid form from wastewater "
streams. Disposal of these wastes would be regulated under RCRA, possibly
under the hazardous waste restriction of Subtitle C. As is the case for
other constituents of flue gas, ultimate isolation of these chemicals
from the biosphere can only be accomplished through diligent controls and
progressive immobilization. All future initiatives to require more
stringent control of air and water effluents must be considered in rela-
tion to the solid waste impacts.
The discussion to follow is organized according to impact issues
as listed in Table 3.1, which includes legislation directly relevant to
the various impact issues.
3.2 Groundwater Related
The most important federal laws pertaining to potential groundwater
contamination attendant to the disposal of FGC wastes are the Resource
Conservation and Recovery Act of 1976 (RCRA), the Safe Drinking Water
Act of 1974 (SDWA), the Surface Mining Control and Reclamation Act of
1977 (SMCRA), and the Federal Water Pollution Control Act as amended in
1977, (FWPCA).
3.2.1 Resource Conservation & Recovery Act and Anticipated Regulations
3.2.1.1 Overview
RCRA (PL 94-580) provides for the regulation of the disposal of
solid and hazardous wastes. The regulatory framework governing the dis-
posal of FGC wastes will depend on the classification of these wastes as
"hazardous" or merely "solid" (non-hazardous) wastes. Federal regulatory
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Table 3.1
Regulatory Framework for Coal Ash and
FGD Sludge Disposal/Utilization
Impact Issue
Groundwater
Contamination
Legislation
Resource Conservation
and Recovery Act of
1976
Administrator
Environmental Protection
Agency, Office of
Solid Waste
Surface Water
Contamination
Physical
Stability
• Safe Drinking Water
Act of 1974
• Clean Water Act
• Marine Protection Research
and Sanctuaries Act
• Resource Conservation &
Recovery Act of 1976
• Surface Mining Control
and Reclamation Act of
1977
Dam Safety Act of 1972
• Federal Coal Mine Health
and Safety Act of 1969
Occupational Safety and
Health Act of 1970
Hazardous Materials
Transportation Act of
1975
• Environmental Protection
Agency, Office of
Water Supply
• Environmental Protection
Agency, Office of
Water Programs
• Environmental Protection
Agency, Office of
Marine Protection
• Environmental Protection
Agency, Office of Solid Waste
• Office of Surface
Mining Reclamation
and Enforcement,
Department of Interior
• Army Corps of Engineers,
Department of Defense
• Mining Enforcement
Safety Administration,
Bureau of Mines,
Department of Interior
• Occupational Safety
Health Administration,
Department of Labor
• Department of Transpor-
tation
Fugitive Air
Emissions
Clean Air Act of 1970
and its Amendments of
1977
• Environmental Protection
Agency, Office of Air
Programs
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Table 3.1 (Continued)
Regulatory Framework for Coal Ash and
FGD Sludge Disposal/Utilization
Impact Issue
Fugitive Air
Emissions
cont'd
Marketing and
Utilization
Legislation
Federal Coal Mine Health
and Safety Act of 1969
• Resource Conservation and
Recovery Act of 1976
• Occupational Safety and
Health Act of 1970
• Toxic Substances Control
Act of 1977
Administrator
Mining Enforcement
Safety Administration,
Department of Labor
EPA, OSW
Occupational Safety and
Health Administration,
Department of Labor
Environmental Protection
Agency, Office of
Toxic Substances
3-10
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authority is more comprehensive for the former: standards for generators,
transporters, and operators of disposal facilities will be more stringent;
and disposal of hazardous wastes is expected to be substantially more costly [45]
RCRA is intended to ensure a broad multi-media approach. The overall in-
tent is to integrate to the maximum extent practicable all provisions of RCRA
with appropriate provisions of the other Acts of Congress which give EPA
regulatory authority. One of the ways EPA has chosen to integrate RCRA with
the Safe Drinking Water Act (SDWA), the Clean Air Act (CAA), and the Clean
Water Act (CWA) is through the use of Human Health and Environmental Standards.
Each of them - the groundwater, surface water, and air standards - establishes
an overriding standard for treatment, storage, and disposal facilities by in-
corporating relevant limitations established under those acts.
Solid wastes are defined in Section 1004 of the act as "any garbage,
refuse, sludge from a waste treatment plant, water supply treatment plant,
or air pollution control facility and other discarded material resulting
from industrial... operations... but does not include... industrial dis-
charges which are point sources subject to permits under Section 402 of
Federal Water Pollution Control Act as amended..."
Hazardous waste is defined in the same section as "a solid waste, or
combination of solid wastes, which because of its quality, concentration,
or physical, chemical, or infectious characteristics may:
a. Cause, or significantly contribute to an increase in
mortality or an increase in serious irreversible, or
incapitating reversible, illness; or
b. Pose a substantial present or potential hazard to human
health or the environment when improperly treated,
stored, transported or disposed of, or otherwise managed."
Subtitle C of the Act - Hazardous Waste Management - requires the
EPA to promulgate regulations identifying the characteristics of hazar-
dous waste and to list specific hazardous wastes "taking into account
toxicity, persistence, and degradability in nature, potential for accumu-
lation in tissue, and other related factors such as flammability, corros-
iveness, and other hazardous characteristics," (Section 3001 (a)).
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Regulations attendant to Subtitle C were proposed on December 18,
1978. These are proposed regulations and may be modified prior to prom-
ulgation by December 1979. There are two separate, but related, issues
involved in determining whether a waste will be regulated, under Sub-
title C, as hazardous:
• Identifying the characteristics of hazardous wastes, and
• Listing specific wastes as hazardous.
According to the December 18, 1978 [8] draft, the Office of Solid
Waste will regulate on the basis of both the list of hazardous wastes and
the characteristics. If a waste is listed, it is presumed to be hazardous.
If a generator believes that his listed waste is not hazardous, the burden
of proof falls on him to demonstrate that it is not hazardous according to
its characteristics. On the other hand, if a waste is not listed but the
generator has reason to believe his wastes are hazardous, he is required
to test these wastes for the suspected failing characteristics. It is
anticipated by the EPA that many utilities will test their wastes to
determine whether or not they can be considered hazardous under the
regulations.
FGC wastes are not listed as hazardous in the December 18, 1978,
proposal. However, in the section entitled "Standards for Owners and
Operators of Hazardous Waste Treatment, Storage, and Disposal Facilities,1?
section 250. 46-2 defines a limited subset of these regulations which are
applicable to "any utility waste* which is defined as a hazardous waste
under Subpart A" where Subpart A is the proposed regulations pertaining to
identification and listing of hazardous wastes. This subset of regulations
will be discussed in more detail below. The key issue here is whether this
specification of utility wastes as a special waste in the hazardous waste
regulations is sufficient grounds to say that generators of these wastes
(utilities) "know or have reason to believe" that their waste may be
hazardous. In that case, utilities would be required to test their waste
and report these tests to EPA. Otherwise, FGC wastes would effectively be
exempted from hazardous waste regulation under Subtitle C.
* Utility waste is defined as fly ash, bottom ash, and flue gas
desulfurization sludges.
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The December 18, 1978, proposal for identifying the characteristics
of hazardous waste defined a number of standard protocols. The most
important one for FGC wastes is the Extraction Procedure (EP) for obtain-
ing a leachate elutriate. If the elutriate contains any substance for which
a. threshold has been established, then the waste is hazardous. Interim
threshold standards have been set for As, Ba, Cd, Cr, Pb, Hg, Se, Ag and
several pesticides based on the National Interim Primary Drinking Water
Standards. It is expected that in the future, thresholds will be established
for other contaminants. Test programs have been ongoing at Oak Ridge
National Laboratory [46]. It appears [42] that preliminary tests on some
TVA Shawnee ash samples indicate that these samples can potentially pass
these tests. The proposal also indicates that other water quality criteria
(e.g., those for protection of aquatic organisms) are being considered for
future use in conjunction with the EP. Figure 3.2 outlines the schematic
as regards FGC wastes in terms of regulatory requirements under RCRA. Under
the special waste provision, engineering standards for disposal of hazardous
wastes under Section 3004 as currently proposed would not apply to FGC
wastes until such time as specific standards are promulgated for those wastes.
One possible course of event in response to these regulations is that
individual utilities around the country would test their wastes according
to the EP, and some of these tests would indicate that the wastes have the
characteristics of a hazardous waste. If a substantial portion of a particular
waste is defined by EPA as hazardous, it would be expected that EPA would
then list that waste as hazardous, and all such wastes would have to comply
with the limited set of regulations identified in 250.46-2, and the complete
set of regulations when they are ultimately promulgated (unless a generator
demonstrates that his particular waste is not hazardous).
EPA is also charged with establishing legally enforceable standards
applicable to generators and transporters of hazardous waste and to
hazardous waste management facilities. Facilities which treat, store, or
dispose of hazardous waste must have permits, either from EPA or a state
hazardous waste program authorized by EPA.
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FGC WASTES
TESTS UNDER
SEC. 3001
PROTOCOL
NOTE: TOXICITY TESTS ARE
MOST IMPORTANT
SEC. 4004
REQUIREMENTS
SEC. 30O4
SPECIAL
WASTES
(STATE IMPLEMENTATION
OF FEDERAL STANDARDS)
CATEGORY
(FEDERAL STANDARDS)
Figure 3.2 Regulatory Requirements - RCRA
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3.2.1.2 The Act
It is the intent of the act to establish national standards and
criteria, but that the individual states would implement and enforce the
regulatory program. However, in the event a state does not become authorized
to conduct the hazardous waste program in that state, EPA will conduct the
hazardous program in that state. Wastes which are identified as hazardous
are to be regulated more stringently at the federal level than non-hazardous
solid wastes. Where RCRA calls for EPA to establish legally enforceable
standards for the management and disposal of hazardous wastes, non-hazardous
waste management and disposal is to be regulated by criteria, which are not
federally enforceable at least by mechanisms clarified at present. State
programs for the management of hazardous waste must be equivalent to the
federal program, consistent with federal or state programs in other states,
and must provide for adequate enforcement. On the other hand, state plans
for solid waste management must meet only certain minimum requirements,
including prohibition of open dumps, as defined by EPA and implementation
of the federal Management and Disposal criteria, and the establishment of
necessary state regulatory powers.
The most important requirement in the area of non-hazardous solid
wastes, as it pertains to groundwater contamination from the disposal of
FGC wastes, is the prohibition of open dumps.
An open dump is defined in the act by exclusion, as any site where
solid waste Is disposed of which is neither a sanitary landfill nor a
facility for disposal of hazardous waste. A facility qualifies as a
sanitary landfill if there is no reasonable probability of adverse effects
on health or the environment from disposal of solid waste at the facility.
The only action which can be taken by the federal government to encourage
state participation and compliance with non-hazardous waste regulations is
in the distribution of funds to the states. $11.2 million are appropriated
for state solid waste plans for fiscal 1979.
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3.2.1.3 RCRA Regulations
The Act is to be administered by the Office of Solid Waste (OSW) of
the EPA, and that office is in the process of developing regulations
required under the Act. On February 6, 1978, OSW published in the
Federal Register proposed rules containing criteria for determining
which solid waste disposal facilities shall be classified as sanitary
landfills, as defined in the Act. It can be expected that these rules
represent the minimum level of control considered acceptable by EPA for
FGC waste disposal.
EPA points out the potential for confusion in the use of the term
sanitary landfill, which traditionally refers to a practice for the con-
trolled burial of solid wastes, especially municipal wastes, whose primary
purpose was disease vector control and for aesthetic value. The defini-
tion contained in the Act is much broader, not only in its definition
of solid wastes but also in the environmental performance requirements of
a sanitary landfill. This is to be accomplished under the proposed rules,
by requiring that usable aquifers* not be endangered beyond the property
boundaries. Endangerment is defined as the introduction of any physical,
chemical, biological, or radiological substance or matter into groundwater
in such a concentration that: (1) makes it necessary for a groundwater
user to increase treatment of the water (including treatment to meet any
maximum contaminant level set forth in any promulgated National Primary
* an aquifer is "a formation... that contains sufficient saturated permeable
material to yield or be capable of yielding significant quantities of water
to wells or springs" and is usable as a drinking water source if it contains
less than 10,000 mg/1 IDS (al.lough states may reclassify aquifers as usable
or unusable) defined in proposed regulations for the state underground in-
jection control program, Federal Register, August 31, 1976, by the Office of
Water Supply, Use of this definition by the OSW in the administration of RCRA
is a good example of coordination of regulatory strategy within EPA.
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Drinking Water Standard under the Safe Drinking Water Act), (2) makes it
necessary for a future user of the groundwater to use more extensive
treatment of the water than would otherwise have been necessary (based
on current technology), or (3) otherwise makes the water unfit for human
consumption. To assure that usable aquifers are not endangered the pro-
posed criteria specify that one of the two following procedures should
be followed:
a. Collection of leachate through artificial liners with subsequent
removal, recirculation or treatment; or
b. Control of the migration of leachate by utilizing natural hydro-
geologic conditions, or soil attentuation mechanisms. Whe^e
appropriate, infiltration of water into the solid waste shall be
prevented or minimized.
Furthermore the rules call for monitoring of groundwater, and prediction
of leachate migration for as long as leachate may endanger groundwater.
Solid waste disposal facilities shall not be located in the recharge
zone of aquifers which are the sole or principal source of drinking water
in the area unless no other sites are technologically or economically
feasible and the facility is located, designed, constructed, operated,
maintained, and monitored to prevent endangerment of the aquifer.
These proposed criteria for the classification of solid waste disposal
facilities are currently under review by OSW pending final promulgation.
Hazardous Waste
The Office of Solid Waste is currently considering key regulations
applicable to owners and operators of hazardous waste management facili-
ties and regarding the criteria for identification of the characteristics
of hazardous wastes and the listing of specific hazardous wastes.
There are several key provisions relevant to FGC waste disposal.
Under Section 3001 of RCRA, EPA-OSW will define hazardous wastes by two
methods:
• Identifying the characteristics of a hazardous waste, and
• Listing specific wastes as hazardous.
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For all practical purposes, listed wastes are presumed hazardous
unless proven non-hazardous by the generator, while unlisted wastes have
to be tested by the generator if he has reason to believe that the waste
is hazardous. However, it is difficult to establish what someone "knows
or has reason to believe" and this section may be difficult to enforce.
The characteristics of a hazardous waste identified by EPA for
immediate regulatory control are ignitability, corrosivity, reactivity,
or toxicity of these, the toxicity test is the most critical one with
respect to FGC wastes [48]. The toxicity test begins with the Extraction
Procedure (EP) which is described in greater detail in Volume 3, and which
consists of:
• Filtration or centrifugation, save liquid.
• Grind or hammer* solid residue.
• Extract in water of pH 5 (but, using no more than 4 ml of
.5N acetic acid per gram of solid).
• Recombine extract with liquid from Step 1.
A joint ASTM/DOE collaborative test program is also being designed
to evaluate leaching procedures.
The waste would be considered hazardous if the extract contains
concentrations of any substance in excess of an established threshold.
Thresholds have been established for As, Ba, Ca, Cr, Pb, Mg, Se, Ag and
certain pesticides based on EPA National Interim Primary Drinking
Water Standards. The thresholds have been set at 10 times the drinking
water standards. Some tests on FGC wastes using the Extraction Procedure
(EP) has been conducted for the EPA by the Oak Ridge National Laboratories
(ORNL) [115]. Tests appear to indicate that EP is effective in removing
inorganic species but not effective for organics. At least one sample
of fly ash seems to pass EP tests [42], Thus, it is likely that some
FGC wastes would be considered hazardous by this criterion.
*This requirement would have some bearing on the acceptability of
treated FGC wastes, where the most beneficial effect of treatment may
be the reduction in permeability. If the waste was structurally weak
and thus vulnerable to the hammer test, this benefit would be discounted
in the evaluation of hazardous characteristics.
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Because many FGC wastes have not yet been fully tested and are
temporarily considered "special wastes?" it is impossible to ascertain
whether such wastes will be regulated as hazardous or non-hazardous. If
found non-hazardous, the wastes would be regulated under Sections 1008
and 4004 of RCRA. However, if specific wastes are tested and found to
have the characteristics of a hazardous waste as stated earlier, a limited
subset of disposal procedures will be required as specified in Section 250.46-2
(Utility wastes) of the regulations. (See Figure 3.2.) Utility wastes means
fly ash, bottom ash, and FGD sludges generated from steam electric power plants.
All storage and disposal facility operators must provide detailed
physical and chemical analysis of each waste stream handled which identifies
the hazardous characteristics of the waste, once, when the facility starts
handling the waste and periodically thereafter.
New facilities shall not be located in:
• An active fault zone,
• A regulatory floodway (as designated by the Federal
Insurance Administration),
• A coastal high hazard area (unless the facility is built
so as to be safe from hurricane and tsunami waves),
• a 500 year flood plain (unless built such that the facility
will not be inundated by a 500-year flood) ,
• Wetlands (unless the facility obtains a NPDES permit and
a Section 404 permit for dredging or filling) ,
• A Critical Habitat Area under the Endangered Species Act
of 1973 (unless it can be demonstrated that the facility will
not jeopardize the continued existence of the endangered and
threatened species), and :
• The recharge zone of a sole source aquifer (unless located,
designed, constructed, operated, and maintained to prevent
endangerment of the aquifer).
Security provisions also exist for such sites, including a 6-foot fence
surrounding the active disposal areas, and a 200-foot buffer zone
requirement.
3-19
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Generators, transporters, and disposers of hazardous wastes are
required to keep a manifest and recordkeeping system.
Post closure care of a hazardous waste facility shall be continued
for a maximum of 20 years (less if the owner or operator can demonstrate
that such care is not needed). The most significant requirements for post
closure care are monitoring for migration of waste constituents and the
uncertain financial liabilities associated with potential ultimate disposal
requirements.
A groundwater monitoring system of four wells is required (less if
there is no potential for discharge to a usable aquifer). One of these-
wells must be upgradient of the site. Baseline monitoring must be per-
formed for at least 3 months prior to startup of any new facility. The
frequency of analysis of groundwater samples varies from one to four
times per year depending on groundwater flow rates. A depth of about
1.5 meters (5 feet) from liner bottom to groundwater is required.
If the monitoring indicates that significant contamination has
occurred, the operator must notify the EPA, determine the cause and extent
of contamination, and discontinue operation until the problem is corrected.
Removal of waste, redesign of liner or other engineering and operational
corrective actions may be required.
3.2.2 Safe Drinking Water Act/Underground Inspection Control Program
This discussion of the Safe Drinking Water Act is limited to the
underground injection control program because this is a potential disposal
method for FGC wastes. The Office of Water Supply (OWS) of EPA is to develop
regulations for state programs covering the underground injection of wastes
via wells for the purpose of protecting groundwater sources of drinking water
EPA has interpreted well mjec ion to include "subsurface emplacement
through a bored, drilled, or driven well or through a dug well where the
depth is greater than the largest su.face dimension, whenever a principal
function of the well is the subsurface emplacement of fluids." (September 23
1977, draft of proposed regulations). EPA must decide which states require
an underground injection control program, and has decided to concentrate
initially on states in which underground injection is commonplace and
groundwater drinking supplies may be endangered, .with subsequent regulation
nationwide. State programs:
3-20
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• May authorize underground injection either by permit or rule,
• Must provide for the protection of drinking water sources, and
• Must provide for inspection, monitoring, record keeping, and re-
porting requirements.
The states have primary authority for enforcement, but if the EPA
finds that the state is not enforcing the regulations, EPA assumes en-
forcement responsibility. Draft proposed regulations (September 23, 1977),
define and prohibit endangerment of usable aquifers and require plugging
of wells within a radius of endangering influence from the injection well,
and generally require procedures to insure that injected wastes will not
migrate from the level of injection upward into a usable aquifer. The
regulations will not substantially restrain the underground injection
of wastes in new wells since they reflect present day best operating
practices.
Based on discussions with EPA, Office of Water Supply, and related
proposed regulations under SMCRA and RCRA, it appears unlikely that State
Underground Injection Control Programs under SDWA will be used to regu-
late mine disposal of FGC wastes. The Office of Surface Mining apparently
intends to regulate these activities under SMCRA, while the RCRA defini-
tion of disposal includes injection of wastes. Thus, there are several
federal laws which may be interpreted to regulate the injection of FGC
wastes in mines, i The Office of Water Supply has indicated that it does
not intend to regulate this activity under SDWA, and apparently OSM or
OSW will regulate this disposal option.
3.2.3 Surface Mining Control and Reclamation Act
The Surface Mining Control and Reclamation Act of 1977 is discussed
more extensively below. Only its pertinence to groundwater contamination
resulting from FGC waste disposal is discussed here. Among the expressed
purposes of SMCRA is to "assure that surface coal mining operations are
so conducted as to protect the environment". Throughout the Act, ground-
water is specifically identified for protection via permit and reclamation
programs.
3-21
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Reclamation plans must:
• Show consistency with local physical environmental and climatolo-
gical conditions,
• Contain the results of test borings or other equivalent information
showing the location of subsurface water, and
• Contain a detailed description of measures to be taken during
the mining and reclamation process to assure the protection of:
- the quality and quantity of surface and groundwater systems, and
- rights of present users to such water.
Reclamation operations must be conducted to prevent long term adverse
changes in the hydrologic balance. Specifically, this would include
changes in water quality and quantity, depth to ground water and changes
in the location of surface water during leaching. Applicable state and
federal regulations have to be met as well. It is suggested in this
standard that water pollution treatment methods can be used but this has
to be secondary to reclamation practices that prevent any of the above
adverse affects. There is a minimal list of such practices, some of
which include lining drainage channels, revegetating, burying and sealing
acid-forming, toxic-forming material, etc. The major issue is whether
or not using sludge material as fill would prevent meeting these specific
requirements of this standard.
Specific detailed requirements are given for sedimentation ponds
which must be used to collect all surface drainage from distributed areas
due to mining or reclamation until drainage from the disturbed area has
met the applicable water quality requirements. The effluent limitations
listed in these regulations include maximum allowable and daily average
values for iron, manganese, total suspended solids, and pH. These are
minimum standards and it is not clear what additional ones might be used or
how the Office of Surface Mining might view such standards in terms of
disposal of waste materials as fill. It is noted that state and federal
regulations also apply.
3-22
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Any acid or toxic materials must be buried and treated when necessary.
Further, water must be removed from contact with such materials. Surface
water monitoring is required after reclamation, with the regulatory
authority determining the scope and frequency and length of data collection.
Backfill materials have to be placed so that adverse affects on ground
water flow and quality are minimized. It appears that offsite effects
are the ones of concern, although there is no indication of the classi-
fication of ground water systems in these regulations as was found in
RCRA regulations. Monitoring of ground water levels and infiltration rates
is required. Additional standards are included for alluvial valley floors,
roads, and permanent impoundments.
Mining operations west of 100° west longitude must not materially
damage the quantity or quality of surface and underground water systems in
alluvial valley floors. It is not clear whether FGC waste disposal in
surface and underground mines will be regulated under SMCRA, RCRA or
both.
Another unresolved issue is the potential inconsistency in ground-
water protection between SMCRA and SDWA. Regulations promulgated by the
Offices of Water Supply and Solid Waste of EPA under SDWA and RCRA have
adopted the philosophy of protecting only usable aquifers from "endanger-
ment" (as defined on page 4). The Office of Surface Mining, on the
other hand, has written regulations which protect "groundwater systems"
from changes in flow and quality, apparently including both usable and
unusable aquifers. Resolution of these issues pends further action by
the Office of Surface Mining.
3.2.4 State Regulations .
The separate States have administrative power over state programs
required under RCRA and SDWA, so long as they meet minimum requirements
established by EPA. Since it is the intent of OWS not to regulate FGC
wastes under this program, the state programs were not reviewed for this
study. However, an earlier review revealed that most state programs are
inconsistent with the proposed federal program and are understaffed for
enforcement. To our knowledge, none of these state programs have con-
sidered the regulation of FGC wastes via underground injection.
3-23
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State solid waste programs are reviewed in greater detail below
where the emphasis is on surface water related issues. It is of interest
then, to note that all state solid waste programs reviewed apply equally
to surface and groundwaters, via definitions that "waters of the state"
include surface and groundwaters.
3.3 Surface Water Related
3.3.1 Introduction
Several unresolved issues dominate the present status of surface-
water-related regulations potentially applicable to land-based FGC waste
disposal. This is not true for ocean disposal, where relatively well-
defined regulations exist for dumping from vessels (under the .Marine
Protection Research and Sanctuaries Act) for outfall disposal (under the
Federal Water Pollution Control Act Amendments of 1972 and 1977), and for
artificial reef construction (discussed below). Principal unresolved
issues for land disposal are:
• Distinctions between definitions of "point" versus "non-point"
sources of water pollution;
• Establishment of a clear hierarchy of regulation integrating the
requirements of RCRA, FWPCA, and SMCRA; and
• Response to the remand of EPA's proposed Effluent Guidelines for
the utility industry.
The importance of these issues may be made apparent by the following
illustrative questions, none of which can be definitively answered at
this time.
1. What surface water discharge criteria apply to a landfill of
FGC waste on utility plant site?
2. What surface water discharge criteria apply to an impoundment
of FGC waste at a location remote from a utility plant?
3. What surface water discharge criteria apply to FGC waste disposal
in a surface mine?
If FWPCA considerations for disposal at remote (off-plant) locations
requires the development of new types of National Pollutant Discharge
3-24
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Elimination System (NPDES) permits, the manner in which such permits
will be defined for various FGC waste disposal options will be signifi-
cant. It is not clear which disposal options would be considered "point
sources" subject to such permitting, and which, if any, would be consid-
ered exempt as "non-point sources". The same issue is further complicated
for disposal in surface mines, which, if allowed, might involve independ-
ent regulation of drainage from "non-point source" disposal areas by
OSM, as well as or in place of "point source" regulation by EPA.
This background of emerging and shifting policies and responsibili-
ties needs to be kept in mind when reviewing the detailed discussions of
individual regulations below.
3.3.2 Surface Water Quality Issues from Point Source Discharges
3.3.2.1 Federal Water Pollution Control Act.
The Federal Water Pollution Control Act established the NPDES permit
program. States may administer their own NPDES program based on EPA
determination that the program (a) will ensure compliance with the Act,
(b) is authorized under state laws, and (c) provides for adequate enforce-
ment. An NPDES permit is required for any point source discharge into
navigable waters. The permit sets maximum permissible effluent levels
for specific pollutants which are established on a case-by-case basis
(in some cases, however, national Effluent Guidelines apply to various
aspects of the NPDES permit). The permittee submits monthly reports of
waste water analyses.
Promulgated EPA guidelines covered effluent discharges from various
sources within a power plant, including fly ash transport water and
cooling tower blowdown, but effluents from FGD systems were not regulated
separately. A summary of the regulated parameters is given in Table 3.2.
It is important to remember that certain aspects of these guidelines were
challenged in litigation and are presently on remand, with revisions
reportedly expected in early 1979. This is discussed more fully in
Section 4.1.4 of Volume 2.
3-25
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Table 3.2
Effluent Parameters Subject to Effluent Guidelines Limitations for the
Steam Electric Power Generation Category
Maximum Daily 30-day Average
BAT
TSS 100 30
Oil and Grease 20 15
Copper 1 1
Iron 1 1
Free Chlorine 0.5 0.2
BAT
As above plus
Phosphorous 5 5
(TSS in rainfall run-off to be limited to a maximum daily of 50 mg/Ji.)
Not all effluent sources subject to all the parameter limitations.
See discussion of remand decision in Section 4.1.4 of Volume 2.
Source: [49]
3-26
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Copper and iron levels from boiler blowdown were covered but metals
in ash transport water were not regulated. BAT regulations, which must
be met for all power plants during the period 1984-1987, and New Source
Performance Standards, were similar to current BPT regulations, but with
the addition of regulation of phosphorous levels. In addition, the reg-
ulations limited run-off from material storage and construction to maxi-
mum daily TSS of 50 mg/£. Other provisions of FWPCA pertinent to power
plants are discussed in Section 4 of Volume 2.
Pollutants Potentially Regulated by Drinking Water Criteria
Data from ten samples of unstabilized FGC waste from eastern and
western coal are given in Table 3.3. It shows the constituents obtained
from the initial leachate from the base of the pile compared to the
corresponding drinking water criteria. All of the elements analyzed and
TSS exceeded the drinking water criteria but not by more than a factor
of 10, with the exception of TSS. Two samples exceeded the range 5-9
for pH. Limited data showed that barium exceeded the drinking water
criterion by a factor of 5, nitrate was at the criteria level and silver
was 0.5 times the criteria level. COD in fresh sludge ranged from 40-
140 mg/jt. It was high for sulfite sludge but this sludge also showed more
rapid oxidation, and after one pore volume displacement had a COD of 10 mg/&
or less.
Pollutants Not Presently Regulated
The major potential pollutants typical of FGC waste effluents and
not presently regulated by effluent guidelines include dissolved solids,
(e.g., Ca and SO,) and trace metals, which can exceed water quality
criteria prior to mixing.
Non-Point Source Discharges
Potential environmental problems associated with disposal of FGC
wastes by landfill include groundwater and surface water contamination
from leaching of dissolved solids and trace metals. Most state regula-
tory authorities are authorized to protect sub-surface waters but only
a few states have specific criteria for groundwater protection. Appli-
cable criteria for Missouri and New York are shown in Tables 3.4A and B. The
criteria for TDS are lower than reported concentrations of dissolved solids
in leachate from unstabilized FGC waste piles.
3-27
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oJ
O
Table 3.3
Comparison of FGC Waste Liquids with Water Criteria
Drinking
Water
Criteria
mg/Jl
As 0.05
Cd 0.01
Cr 0.05
Pb 0.05
Hg 0.002
Se 0.01
F 2
TDSb
pH (actual
i \ C
vt lues)1-
Range of
All
Samples A
<0.8-2.8 0.6
0.4-11 5.0
0.22-5 5.0
0.2-6.6 0.8
0.03-2.5 2.5
0.28-63 10.0
<0.5-5
6.L-48.5 36
6.7-12.2 6.7
Concentration - Criteria (Nondimensional)
Sample3
B C
0.4 2.0
1.2 0.4
0.8 1.8
3.0 4.6
—
3.3 10.0
0.5 3.3
6.6 30.0
6.8 8.0
D B
0.04 0.4
11
0.6
<0.2 6.6
<0.1 <0.5
4.2 <2
1.7
13.4 18.8
12.2 8.7
F G H
1.2 2.8 0.1
1.3
0.2
0.2 <0.2 <0.2
<0.001 <0.1 <0.1
7.8 63 14
1
20.5 28 18.4
8.0 7.8 7.3
I J
0.8 0.2
5 2.5
1.1
0.8 <0.1
0.1 0.03
2.8 0.3
5 <0.5
8.4 48.5
10.7 8.9
a
Sample data are as follows:
Sample
A
B
C
D
E
F
G
H
I
J
Station
Mohave
Cholla
Shawnee
Shawnee
Shawnee
Shawnee
Shawnee
Shawnee
Duquesne Phillips
LGE Paddy's Run
Absorbent
Limestone
Limestone
Limestone
Limestone
Lime
Lime
Lime
Gypsum
Lime
Carbide Lime
% Ash
3
59
40
6
40
6
6
6
60
12
Sampling Data
Mar 1973
Nov 1974
Jun 1974
Jan 1977
Jun 1974
Sep 1976
Oct 1976
Aug 1977
Jun 1974
Jul 1.976
Assumed 500.
cPrlmary water supply criteria for most states are in ranges of 6.5 to 8.5 or 5 to 9.
Source: [50]
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U)
I
ho
Table 3.4a
Discharge Criteria in New York and Missouri
State of New York*
Groundwater Contaminant Limits
State of Missouri
Groundwater Contaminant Limits
Concentration in mg/i
Substance
Alkyl benzene sulfonate (ABS)
Arsenic (As)
Barium (Ba)
Cadmium (Cd)
Carbon chloroform extract
residue (CCE)
Chloride (Cl)
Chromium (hexavalent) (Cr-rt)
Copper (Cu)
Cyanide (CN)
Fluoride (F)
Iron (Fe)
Lead (Pb)
Manganese (Mn)
Nitrate (N)
Phenols
Selenium (Se)
Silver (Ag)
Sulfate (SOA)
Total dissolved solids
Zinc
pH**
Schedule I
1.5
0.1
2.0
0.02
0.4
500
0.10
0.4
0.4
3.0
0.6
0.10
0.6
20.0
0.002
0.02
0.10
500
1000
0.6
6.5-8.5
*New York State Groundwater Classifications
Standards (Part 703).
A A **U A..* »-l A A
Schedule II
1.0
0.05
1.0
0.01
0.2
250
0.05
0.2
0.2
1.50
0.3
0.05
0.3
10.0
0.001
0.01
0.05
250
500
0.3
6.5-8.5
and
* A£
Contaminant
Arsenic
Barium
Cadmium
Chromium (Total)
Copper
Cyanide
Fluoride
Lead
Nickel
Phenols
Selenium
Silver
Zinc
COD
Threshold Odor Number (TON)
Linear Alkylate Sulfonates
Chlorides
Sulfates
Total Dissolved Solids
Nitrate as (N03)
Heavy Metal Ratio shall not
Cu Zn . Pb Cr
20 100 50 500
Maximum Value
Allowed
50 ug/£
1,000 Mg/1
30 wg/*
500 vg/fc
20 MgM
10 ug/Jl
1,200 ug/i
50 ug/i
800 ug/l
5 ug/*
10 ug/i
50 vg/i
100 wg/i
10 ug/1
3
1.0 mg/t
250 mg/1
250 mg/l
500 mg/1
10 mg/1
exceed 1.00:
"30" + 800 " 1'°l
range indicated above, the natural pH may be one
extreme of the allowable range.
Where the abbreviation for the metal In the fraction
is the measured concentration in the effluent in
micrograms per liter (yg/Z.).
•Missouri Groundwater Recharge and Irrigation
Return Water (Appendix: III).
-------
Table 3.4B
National Interim Primary Drinking Water Regulations
Maximum Contaminant Levels for Inorganic Chemicals*
Level
Contaminant (mg/Jl)
Arsenic 0.05
Barium 1
Cadmium 0.010
Chromium 0.05
Fluoride **
Lead 0.05
Mercury 0.002
Nitrate (as N) 10.
Selenium 0.01
Silver 0.05
Federal Register, p 59570, December 24, 1975.
**
Fluoride is regulated as a function of average
daily maximum air temperature:
Air Temperature Fluoride Level
12.0 2.4
12.1-14.6 2.2
14.7-17.6 2.0
17.7-21.4 1.8
21.5-26.2 1.6
26.3-32.5 1.4
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3.3.2.2 Surface Mining Control and Reclamation Act Promulgated
Interim Enforcement Provisions
The "Surface Mining Control and Reclamation Act" was passed in August
of 1977. Resultant interim regulations have been in effect since December
1977. The proposed permanent regulacory program was published in September
1978, with final regulations expected in 1979.
The interim standards issued for reclamation requirements as a
result of SMCRA include protection of surface water. It is at present
unclear how these performance standards will be applied to a situation
where FGC waste material is disposed of in a mine. The Office of Surface
Mining in the Department of Interior has indicated that it will develop
a position on this issue during 1979. For the present, it is assumed
that requirements of standards for reclamation would have to be met if
FGC wastes were disposed of in mines.
The interim regulatory program requires that all surface drainage be
passed through one or more sedimentation ponds. This would produce a
point source discharge. The regulations require that such discharges
meet applicable state and federal laws, but at a minimum must meet the
following effluent limitations-'-:
Average of Daily Values for
Effluent Characteristic Maximum Allowable 30 Consecutive Discharge Day
Iron, total 7.0 mg/S- 3.5 rog/X,
Manganese, total 4.0 mg/£ 2.0 rag/*.
-Total suspended solids 70.0 mg/£ 35.0 mg/fc
pH within the range
of 6.0 to 9.0
Treatment must be used if limitations are not met (although sedimen-
tation ponds can be a form of treatment). For a number of the mountain and
western states, total suspended solids will be determined on a case-by-case
basis, and the limitations for this parameter are somewhat more restrictive.
Adapted from "Surface Mining, Reclamation and Enforcement Provisions,"
Dept. of the Interior, Office of Surface Mining Reclamation and
Enforcement, Dec. 13, 1977.
3-31
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The commentary process on these regulations indicated that EPA may
have more stringent limitations under FWPCA, which would have to be met.
In addition, the limitation for manganese in the interim program is appli-
cable only to acid drainage [51]. This change was based on the fact that
there was reported to be insufficient data to justify limitations on man-
ganese in alkaline waters.
For underground operations, similar effluent limitations apply to discharge
from sedimentation ponds. In addition, any discharge from areas disturbed
by underground or surface mining, must meet state and federal regulations
and the effluent limitations established in these standards. It is not
clear how disposal of FGC wastes in deep mines will be viewed as this issue
is not explicitly covered by the interim regulations. For the present, it is
assumed by the authors that such disposal would be permitted provided all re
ulatory standards for water, etc. could be met. In particular, the regulati
establish particular measures to prevent water pollution from mine drainage,
which include:
• Diverting water from underground workings»
• Preventing water contact with toxic-forming materials and
minimizing contact time with waste (as defined by SMCRA
regulations), and
• Maintaining barriers to enhance post-mining inundation
and sealing .
It would appear that these measures, at least the first two, would make dis-
posal of non-mining wastes more acceptable.
Proposed Permanent Regulatory Program
The proposed regulation, promulgated on September 18, 1978 for the perma-
nent regulatory program under the Surface Mining Control and Reclamation
Act have several important changes over the draft form of these regulations
that were circulated in July 1978. One key difference concerns the
"discharge water into underground mines." Under the draft regulations, the
following requirements were stipulated:
3-32
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"The regulatory authority may approve the discharge of water into
abandoned mine voids when the water is used as an integral com-
ponent of any operation conducted for the purpose of water dis-
posal, fire extinguishment, or subsidence control, and provided
that
(1) the hydrology of the ground or surface water approximate
to the disposal area is not affected,
(2) the mine water pool remains essentially static,
(3) such water is treated for any and all pollutants if it is
discharged on the surface, and
(4) introduction of water into the voids is acceptable when
all other geologic factors have been considered.
The source of water shall be designated prior to its mixture and
injection, and any and all affects on the hydrology and geology
of the subjacent as well as superjacent strata shall be specified."
This section changed substantially in the September 18th publication.
"Surface water shall not be diverted into underground mine workings
unless the person who conducts the surface mining activities
demonstrates to the satisfaction of the regulatory authority
that the diversion will—
(a) abate water pollution or otherwise eliminate public
hazards resulting from underground mining; and
(b) be discharged as a controlled flow meeting the water
quality requirements of Section 816.52 for pH and
total suspended solids except that the total suspended
solid concentration may be exceeded only if the sus-
pended material is approved by the regulatory authority
or is limited to—
(2) fly ash from a coal-fired facility;
(4) flue gas desulfurization sludge;
(c) the discharge will not cause, result in, or contribute
to a violation of applicable water quality standards;
(d) minimize disturbance to the hydrologic balance."
(Section 816.55, Surface Mining and Reclamation Operations, proposed rules
for permanent regulatory program.)
3-33
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This is one means by which the Office of Surface Mining could control
underground injection of materials into underground mines in lieu of EPA
regulations of similar types of land disposal.
The discussion accompanying these proposed rules is interesting in that
comments are made on the development of the water quality standards of the
Surface Mining Control and Reclamation Act. The following are quotes from
this discussion (Federal Register, Volume 43, No. 181, pages 41744-41745) :
"In developing these standards, an alternative considered by the
drafters in response to public comment was to do no more than
incorporate by the reference EPA's Effluent Guidelines and
Standards for the Coal Mining Point Source Category under the
National Pollution Discharge Elimination System Permits Program.
This alternative was analyzed and rejected for several reasons.
"First, the proposed effluent limitations would be applied through-
out the entire phase of surface coal mining and reclamation
operations, as required for the protection for the hydrologic
balance . . . whereas EPA's effluent limitations regulations
apply only to the active phase of mining operations . . .
"A second reason why this alternative is not being adopted is
that U.S. EPA's regulations apply only to existing point
source discharges of water from mining operations and do not
apply to non-point source discharges . . .
"The third reason why the use of EPA's regulations alone is
believed to be insufficient is that these regulations do not
apply at all to discharges of ground water."
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3.3.2.3 Surface Water Quality Issues Related to Runoff: Issues Defined
By Existing and Emerging Regulations
RCRA
Regulations under Section 3004, concerning standards applicable to
owners and operators of hazardous waste treatment storage and disposal
facilitites have been proposed by EPA (December 18, 1978). Priority
issues relating to surface water contamination by runoff from hazardous
waste treatment, storage, and disposal facilities (which are addressed
by the standards) include site selection, design, monitoring, and closure
of such facilities.
The legislation requires the integration of RCRA with existing regula-
tions to the maximum extent practicable. Hence, it is expected that the
performance standards established by the regulations under Section 3004
will interface with the point source permitting authority NPDES established
under the Federal Water Pollution Control Act (FWPCA) (PL 92-500).
An important consideration with respect to the regulations under
this section concerns discharges to surface waters other than navigable
waters. Proposed regulations under RCRA reference the NPDES (permit)
regulations under FWPCA which are applicable only to point source dis-
charges to navigable waters, which is not a restriction on RCRA juris-
diction. Controversy may arise over any expansion of the NPDES permit
program beyond the jurisdiction of FWPCA. A related area of concern may
be the integration of RCRA with existing federal legislation emphasizing
other water quality considerations (e.g., the Safe Drinking Water Act).
It appears likely the facility siting considerations will be given an
emphasis under the regulations for Section 3004. Such siting consider-^
ations may be viewed primarily in terms of land use (I.e., location with
respect to residences, roads, etc.) and safety (location with respect
to active faults). However, there may also be consideration of issues
critical to surface run off in the site selection criteria. In par*-
ticular, the location and design of facilities which may be subject to
"worst case" run off situations (i.e., flood conditions) may be of par-
ticular concern with respect to the treatment, storage, and disposal of
hazardous wastes.
3-35
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Without proper maintenance or monitoring, surface runoff and other
discharges from closed facilities may continue to affect water quality
long after the operations of such facilities have ceased. The proposed
RCRA regulations address this problem within the context of Section 3004.
The Legislative requirements for continuity of ownership and financial
responsibility may be utilized to require owners to make provision for
monitoring and maintenance of closed facilities, as well as insuring that
such facilities are closed in a safe manner consistent with the public
helath and environmental safety.
Specific requirements for monitoring of surface waters, emphasizing
waters on site, are required with respect to the determination of contam-
ination. Visual inspections are also likely to be required, to insure
that maintenance operations are effective in the prevention of unantici-
pated hazards or discharges.
The December 18, 1978, proposed regulations [8] pursuant to Section 3004
temporarily exempt FGC wastes from hazardous waste disposal procedure
standards, including those which address the control of runoff and leach-
ate. The regulations classify FGC wastes as "special" to be subject to
further rulemaking at some point in the future. The regulations imply
that some, but not all, FGC wastes may be subject to the disposal require-
ments for hazardous wastes on a case-by-case basis if tests do warrant.
Effluent Related Issues of Proposed Federal Regulations
Effluent related issues considered within the context of RCRA may be
viewed in terms of the classification of material as having either a
hazardous or non-hazardous nature. Hazardous materials will fall under
the jurisdiction of Federal regulations. Certain components of a waste
which are considered particularly hazardous may receive special attention
in regulations. Such components include boron, molybdenum, selenium,
which are often present inf FGC waste, but which are likely to be pro-
hibited for disposal via landfarming when present in waste material.
Other components which could receive special attention in the regulation
with reference to landfill as a disposal option include cyanide, arsenic
chromium, and other heavy metals.
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Effluent from the treatment or processing of wastes, particularly
hazardous wastes, could be classified as constituting a hazard to health
and the environment, and therefore, controlled under the regulatory pro-
visions for the various disposal options under Section 3004 (subject, of
course, to the criteria established for the determination of hazardous
waste under Section 3001).
State Programs Under RCRA
Subtitle D of RCRA is entitled "State or Regional Solid Waste Plans."
Among the objectives of the subtitle are to provide for federal guidelines
for state solid waste disposal plans; establish procedures for develop-
ment and implementation for such plans; and provide for federal assistance
to the states for activities such as facilities studies, technology
assessments, legal expenses, etc., in connection with the planning effort
and the implementation of programs.
The criteria for determining which solid waste disposal facilities
pose no reasonable probability of adverse effects on health or the envir-
onment (Federal Register, February 6, 1978) through degradation of surface
waters include the compliance of point source discharges (including
collected surface runoff) with the National Pollutant Discharge Elimina-
tion System (NPDES) permits issued under Section 402 of the FWPCA amend-
ments. Additional criteria include the control of non-point source dis-
charges (including surface runoff) to prevent or minimize such discharges
into any off-site surface water.
The objectives of the RCRA "non-hazardous" waste landfill surface
water criteria are to assist in attaining the objectives of the FWPCA.
The permit requirements under Section 402 of that Act provide the method
for the regulation of point source discharges which may have adverse
affects on surface waters. The criteria provide for additional controls
on non-point source discharges, to the extent that such discharges be
"prevented or minimized." To comply with these requirements, non-point
source discharges can be collected, by channeling into a ditch or trench,
and regulated as point-source discharges. Collection of non-point sources
(i.e., surface leachate, leachate seepage, and including surface runoff)
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creates a point source, which is required to comply with the NPDES permit
if discharged to off-site surface waters. These criteria under RCRA
thus deal with both point and non-point source discharges from solid
waste disposal facilities by deferring to the FWPCA with respect to the
former; and by establishing criteria for the states to use in regulating
the latter, which, in effect, require that the discharges, including
surface runoff, be considered as a point source. Thus, most discharges
from solid waste disposal facilities can be subject to the requirements
of the NPDES permit.
In total, the proposed criteria are interpreted to comply with the
requirements of Section 1008 (a) (3), which authorize guidelines "
to provide minimum criteria to be used by the states to define those
solid waste management practices which constitute the open dumping of
solid waste or hazardous waste " The criteria in addition suggest
guidelines under Section 1008 (a) (2c~), providing for the " protection
of surface waters from runoff through compliance with effluent limitations
under the FWPCA, as amended "
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3.4 State Requirements and Plans
3.A.I Present Status
The states are at various stages in regulating and planning for the
management and disposal of solid wastes. Presented are brief descriptions
of the legislative and regulatory requirements of selected states which
have been suggested by EPA staff at regional and national levels to be
relatively advanced on the issues of solid waste management and disposal.
Table 3.5 lists the states whose solid waste regulations are discussed
in the subsequent pages of this report.
Region I: Maine
Solid waste management regulations were promulgated under Title 38,
Maine revised statutes, Section 1304, and became effective in February
1976. Chapter IV of the regulations addresses land disposal options.
Section 406.1 specifies that a solid waste disposal site boundary shall
not lie closer than 300 feet to a classified body of water, nor closer
than 1,000 feet to a potable water supuly. The Department of Environmental
Protection deems these buffer zones to be sufficient to protect surface
water. Other requirements to protect surface water include moderate
slope (i.e.. less than 15%) and "good design and operation." Sites not
meeting the site characteristics criteria may be approved if "... good
design and operation can be shown to provide adequate protection to
surface ... water resources."
One element of design which the Department will review is the
diversion of surface waters away from the proposed disposal site.
Drainage systems will also be reviewed before any plan is approved.
The determination of whether or not a waste is hazardous will be
made by the Department on request. The state apparently does not have
a hazardous waste management program at present. The requirements of
RCRA are expected to be incorporated into the solid waste management
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Table 3.5
Management and Disposal of Solid Wastes in States
State Whose
Regulations
Federal Region are Discussed
I Maine
II New Jersey
III Pennsylvania
IV Tennessee
V Illinois
VI Texas
VII Kansas
VIII California
IX Oregon
The states listed were chosen for illustrative
purposes. All 150 States are at various stages
of planning or implementing management of solid
waste disposal operations.
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plan now being drafted; and are expected to substantiate and reinforce
the states existing regulations. Hazardous wastes in the state are
likely to be more stringently controlled in the state as RCRA
Subtitle C regulations are promulgated an^ become effective.
Region II: New Jersey,
The New Jersey Solid Waste Management Act was passed in 1970; important
amendments to the Act were passed subsequently, including Chapter 326,
passed in 1975. The Act and its amendments address solid waste manage-
ment planning in the state and issues concerning collection and dis-
posal of solid waste.
For planning purposes, each of the 21 counties in the state and the
Hackensack Meadowlands District was designated" a solid waste management
district. Two groups of districts are required to have plans completed
by early 1979; the third group of districts must complete plans by mid
1979. Plans are required to cover a ten year period and are to be
updated every two years.
With respect to hazardous wastes, the legislation requires monitoring
wells to be installed at any site accepting hazardous or chemical
wastes, bulk liquids or pesticides. Discontinued acceptance of the
waste and implementation of "an acceptable system of interception,
collection, and treatment" is required if analyses indicate a hazard
or potential threat to water quality. The legislation also requires
interception, collection, and treatment of all leachate generated at
a solid waste facility. The effective date of the regulation is set
at 1980.
The regulations prohibit any new sanitary landfill to be constructed where
solid waste is or would be in contact with surface or groundwaters. A
similar provision applies to existing landfills. The impairment or
further degradation of surface or groundwaters as a result of solid
waste disposal activity or leachlate generation is prohibited. Ground
water monitoring is required of new facilities.
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The only specific mention of by-products resulting from air pollution
control devices was in the context of the disposal of incinerator
residues.
The New Jersey definition of hazardous waste is broad and bears
similarity to the legislative definition in RCRA. There is citation
of the definitions of toxicity determined under the Occupational Safety
and Health Act, and hazardous materials classification of the Department of
Transportation. RCRA., however, post-dated the legislation and is not cited.
The New Jersey legislation is considered to have anticipated the require-
ments of RCRA in some respects, including the designation of planning
districts and the development of solid waste management plans. New
Jersey also requires a manifest system for tracking of hazardous
wastes. Reduced incidence of ocean dumping is expected to result in
increased emphasis on land-based disposal in this densely populated
state.
Region III; Pennsylvania
The Commonwealth is in the process of revising the state solid waste
management plan. The Solid Waste Management Act was passed in 1968
as Act 241. Regulations under the Act are found in Chapter 75 (Solid
Waste Management Rules and Regulations).
The planning process is addressed in Subchapter B of Chapter 75. Solid
waste management planning in the Commonwealth is initiated at the level
of the municipalities. Subchapter C addresses permit and standards
for disposal facilities. The design criteria for sanitary landfills
address the issue of surface water contamination through set-back
requirements (25 feet) and requirement for the management of surface
water. In addition, "the site shall be designed and operated in a
manner which will prevent surface water percolation into the solid
waste material deposits." Section 75.37(e) addresses surface water
management techniques for the standards for fly ash f bottom ash or
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slag disposal areas. The provision may be appropriate to FGG wastes
as they may include fly ash. Surface runoff from "adjacent areas should
be diverted avay from flyash on slag disposal piles (s)...(and)
run-off shall not be allowed to discharge freely onto the slopes of
the fill." In addition to these requirements for control of runofT,
it may be necessary to provide "contingency plans for treatment of
run-off from the fill..."
Section 75.38 addresses general standards for industrial and
hazardous waste disposal sites. The definition of hazardous waste
in the context of these regulations is similar to that set forth
in RCRA. To date, the Department of Environmental Resources has
reportedly not had adverse reactions to its enforcement of the regula-
tion with respect to hazardous waste. Specific reference to possible
surface water contamination by runoff with the context of the design
and operating requirements of this section are limited.
Region IV: Tennessee
This state only recently passed solid waste management legislation, but
is reported by EPA staff to be further along than other states in the region.
The legislation incorporates elements similar to those specified in RCRA,
including a manifest system for hazardous wastes and an inventory of
open dumps. Regulations under the law may be delayed until critical
issues are resolved at the federal level, including the determination
of what constitutes a hazardous waste. As the regulatory process
proceeds, problems with respect to on-site disposal options and regula-
tion of hazardous wastes are considered possible. Hazardous waste
criteria and a listing of hazardous wastes are required by the
legislation.
The criteria under consideration for determining whether a waste is
hazardous are very similar to the criteria under consideration by
EPA, as authorized by Section 3001 of RCRA. It is expected that the
Tennessee regulations will closely parallel the federal regulations
under that section for most classifications (e.g., reactivity,
toxicity).
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Detailed studies of disposal site hydrologic characteristics may be
required under the state regulations, prior to the approval of a
disposal site. Issues to be examined with respect to surface water
in location and design studies include: site location and drainage
relationships with contiguous areas; proximity to surface streams
and potential for flooding; and seasonal variation in water quality,
evaluated for a number of parameters. Site specific criteria under
consideration for the evaluation of disposal sites address issues
related to surface runoff. Surface runoff from contiguous areas
is expected to be controlled and not allowed to enter a
disposal or a landfarm site. Moreover, location and design of a
site is unlikely to be approved if the possibility of degradation
of surface waters attributable to the site exists. Special precautions
are likely to be instituted to prevent exposure of a site to flood
waters. Federal regulations under RCRA Section 3004 may also be
utilized in the evaluation of disposal and landfann sites. The
performance standards under that section may also be applied by the
State of Tennessee to hazardous waste storage, treatment, and
disposal facilities. Other criteria and standards may also be -used
if demonstrated to be equivalent to the federal standards.
Region V; Illinois
The Illinois Environmental Protection Act (Illinois revised statutes,
Chapter 111 1/2, 1001-1051) establishes the authority of the Illinois
Pollution Control Board (the Board) to adopt regulations which are, in
effect, consistent with the purposes of the RCRA (e.g., the prohibition
against and/or regulatory control of open dumping). Under Title V,
Sections 21 and 22, the Board as authority to set design and performance
standards for "refuse collection ard disposal sites and facilities," where
refuse is broadly defined to includr garbage and other discarded materials.
In addition, the Board has autnority to set standards for handling, storing,
processing, transporting and disposal of hazardous refuse. Hazardous
refuse, in the context of the Illinois legislation, is defined as "refuse
with inherent properties whicl. make such refuse difficult or dangerous to
manage by normal means, including chemicals, explosives, pathological wastes
-------
and wastes likely to cause fire." Significantly, the definition of hazardous
waste in this section of the Illinois legislation emphasizes primarily the
inherent difficulty in management as the fundamental criterion for the
determination of hazard, rather than the danger posed to the health of
those exposed to the waste.
Title III, Sections 11 and 12 of the Illinois Environmental Protection Act
address issues of water pollution in the state. Section 12(a) prohibits
"the discharge of any contaminants into the environment in any state so as
to cause or tend to cause water pollution in Illinois"; while Section 12(d)
proscribes the "deposit (of) any contaminants upon the land in such manner
so as to create a water pollution hazard...." Taken together, these para-
graphs may be interpreted to prohibit the disposal of any "contaminants"
on the land if such disposal endangers surface or ground waters, and nay
also be interpreted to prohibit unregulated surface runoff from a waste
disposal site, if such runoff could result in the contamination of surface
or ground waters.
In fact, the Illinois Pollution Control Board regulations state "no person
shall cause or allow the development or operation of a sanitary landfill unless
the applicant proves to the satisfaction of the agency that no danger or hazard
will result to the waters of the state because of the development and operation
of the sanitary landfill." While the rule does not specifically address the
issue of surface runoff from a landfill site, runoff which dees constitute
a hazard to surface or ground waters could be interpreted to violate the
intent of the rule. Rule 313 prohibits the discharge of contaminants into
the environment so as to cause, or tend to cause, water pollution, placing
regulatory authority behind the legislative intent of Title III, Section 12(a)
(see above).
Hazardous or liquid wastes and sludges may be accepted at a sanitary landfill,
if authorized by permit, under rule 310, which regulates disposal of
Chapter 7, Part III, "special wastes." Thus, the possibility of FGC wastes
being disposed of at sanitary landfill sites in Illinois exists, with such
disposal being regulated within the context of Chapter 7.
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Regulations addressing the transportation of special wastes are expected to
be proposed by the Board. The primary focus of the regulations is anticipated
to be on the issuance of permits to special waste haulers; to provide pro-
cedures for the inspection of numbering of vehicles, tanks and drums; and to
require the legal hauling of special wastes to approved disposal, storage,
and treatment sites. It is significant that pollution control residuals
may be considered a sub-classification of special wastes but any person
hauling only coal combustion fly ash may be exempted from the permit require-
ments of the regulations. The wording of this possible exemption may be
critical, since admixtures of FGC sludge with fly ash may not meet the
criteria for the permit exemption.
It is of interest to note that the maintenance and submittal of operatine
records required by Rule 317 apparently include the submittal, four times per
year, of water monitoring data (e.g., comprehensive analysis of water samples
from on site and nearby wells and surface waters). Thus, the Board is able
to monitor whether water quality standards have been violated by operation
of landfill. It is also of interest to note that a hazardous waste disposal
site in the state was ordered closed by a circuit court judge in 1978, due
to possible ground water contamination. The order to close, which also
required removal of wastes and contaminated soil, was termed "landmark"
by the state's Attorney General's Office.
Region VI: Texas
Solid waste regulations for the state of Texas were promulgated under th
Texas Solid Waste Disposal Act of 1969, as amended. The Texas Departments
of Health and Water Resources are jointly responsible for implementation
and enforcement of regulations authorized by the act. The Office of Solid
Waste Management of the Department of Health is primarily responsible for
the management of municipal solid wastes; industrial solid wastes fall within
the jurisdiction of the Department of Water Resources. The protection of
surface waters are among the criteria considered in site selection and
facility design. In particular, the criteria stipulate the control of
surface drainage on a land disposal site to "minimize surface water runoff
onto, within, and off the working area." This control is to be affected
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by "dikes, embankments, drainage structures and diversion channels of adequate
size and grade...to control surface water." Special requirements are also
in effect with respect to protection of a site from 50- and 100-year frequency
floods.
Operational requirements for most conventinal landfill sites include the
following:
"1. Solid waste shall not be placed in unconfined waters which
are subject to free movement on the surface....
2. The site shall be protected from flooding by any nearby streams
with suitable levels....
3. Suitable water diversion methods shall be provided to divert
the flow of uncontaminated runoff or other surface water away
from the active disposal area.
4. Rainfall runoff within the landfill area that has been contaminated
by solid waste on other polluted waters shall not be discharged
from the site unless the site operation...is authorized by the
Texas Water Quality Board."
There is a provision in the regulations for the disposal of other sludges
"only if special provisions are made and approved by the Department." No
definitions or examples of "other sludges" are provided, and it is unclear
what the term "other sludges" may include. Department approval is also
required for disposal of hazardous waste.
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Region VII: Kansas
The Kansas Solid Waste Management Act addresses first the organization and
planning of solid waste management in the state. The act also focuses on
permit requirements for the construction, alteration or operation of a
solid or hazardous waste processing facility on disposal areas. The conditions
of the permit are authorized to be designed so as to "protect human health and
the environment and to conserve (the disposal or processing) site." The
Secretary of the Department of Health and Environment has statutory authority
to approve the types and quantities of solid waste allowable for processing
or disposal at a permitted authority.
"Dumping or disposal of any solid or hazardous waste onto the surface of the
ground, or into the waters of the state" is deemed unlawful without having
obtained a permit. A condition for issuance of a permit includes departmental
approval for the installation and operation of environmental quality monitoring
systems, including monitoring wells.
The standards for disposal sites addressed in the revisions of the regula-
tions are expected to require that "surface runoff and leachate seeps
shall be controlled so as to minimize non-point source discharges into surface
waters." Specifications for such control are not detailed in the revisions
to the regulations.
Hazardous wastes are defined in Section 64-3402 (Kansas Solid Waste Managment
Act) as solid wastes which, because of quantity, concentration, or physical,
chemical or infectious characteristics, pose a hazard to the environment or
are dangerous to human health if improperly managed. As in the Illinois
statutes, the technique of management, in addition to inherent characteristics
of the waste, is considered t contribute to a substantial present or
potential hazard. Significantly, the revisions to the standards for manage-
ment of solid waste are application LJ (a) waste which consists of or contain
hazardous wastes; and (b) any mixture formed by combining any waste or substance
with a hazardous waste (emphasis added). The regulations might thus be
interpreted as applicable to FGC wastes, which include trace metal species
which may be viewed as hazardous. The burden of proof as to whether
a waste containing components with hazardous properties listed by
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the Department, but the criteria are still being developed.
Industrial wastes, i.e., those wastes not suitable for discharge to a
sanitary sewer and treatment plant, may not be disposed of without a
disposal authorization by the department.
Location, design and operation guidelines will be developed by the department.
The standards for hazardous waste disposal area (facility closure) require
the covering of cells with an impervious layer to minimize leachate and
contaminated runoff. Maintenance of land disposal areas after closure will
include treatment of contaminated runoff.
The Kansas regulations incorporate many of the requirements of RCRA, including
the local solid waste management plans; manifests, and reporting requirements;
and standards applicable to generators, treatment and disposal facility
operators and transporters. The regulations discussed here will be implemented
on a temporary basis pending legislative review in 1979.
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Region VIII: California
The California Solid Waste Managment and Resource Recovery Act of 1972
and the Hazardous Waste Control Act are the two fundamental statutes
relevant to the disposal of solid and hazardous wastes in the state. The
Solid Waste Management Board (Board) and Department of Public Health
(Department) are the two state agencies with primary responsibility for,
respectively, solid and hazardous wastes.
The Board has authority in the legislation to formulate and adopt minimum
standards for solid waste management to protect air, water and land from
pollution. Standards addressed include the location, design, operation,
maintenance and ultimate reuse of solid waste processing and disposal
facilities. The Board must also review compliance of local solid waste
management plants with state policy (plans are to be reviewed every three
years).
The Board also retains permitting authority for the operation of solid
waste facilities. The operation of such facilities without a permit is
prohibited.
The conditions of the permit are not specified in the legislation.
Determination of whether FGC wastes would be permitted for disposal at a
solid waste disposal site has not been made by the Board, and would depend
on an analysis of the physical and chemical characteristics of the waste.
A finding that the waste is hazardous would place its disposal within the
jurisdiction of the Department of Public Health. The Department is authorized
by legislation to make a listing of hazardous wastes, and regulation criteria
and guidelines for the identification of hazardous and extremely hazardous
wastes. The Department also sets minimum standards for operating pro-
cedures, including handling, processing, use, storage and disposal of hazardous
wastes. In addition, the Department sets standards for the use and operation
of hazardous waste facilities.
The legislation is specifically concerned with the protection of public
health and safety and that of domestic and wild life. To this extent, though
not explicitly, the legislation addresses the degradation of surface water
quality by runoff.
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Region IX; Oregon
Solid waste regulations for the State of Oregon were authorised under
Chapter 459 and subsequent amendments. Hazardous wastes are specifically
addressed in Section 459.410-690 of the statute. The regulations contained
in the Oregon administrative rules pertaining to solid waste management
are likely to be revised and expanded during 1978. The new rules, however,
have not been proposed by the Department of Environmental Quality (DEQ) at
the time of this writing. Hence, the discussion will focus on the old rules
presently in force. In addition, current rules pertaining to the management
of environmentally hazardous wastes are expected to be completely revised
during early 1979. It should be recognized that the regulatory requirements
in the State of Oregon with respect to the management of solid and environ-
mentally hazardous wastes may be significantly altered before 1980. How
the revised regulations will be influenced by the developing regulatory
framework authorized at the federal level under RCRA is yet undetermined.
In certain respects, Oregon is considered to have progressed quite far in
the management of environmentally hazardous waste. The state reportedly
has the only licensed and regulated hazardous waste disposal site in operation
west of the rockies. Environmentally hazardous waste disposal sites are
licensed and regulated under Chapter 340, Section 6, Subdivisions 2 and 3
of the Ohio administrative rules. Subdivision 2 specifies the procedures for
issuance, denial, modification and revocation of licenses for the disposal
of environmentally hazardous wastes. Subdivision 3 establishes "requirements
for environmentally hazardous waste management from the point of waste
generation to the point of ultimate disposition..." and addresses the classi-
fication and declassification of environmental hazardous wastes. The general
requirements of the subdivision bear similarity to certain requirements of
RCRA, such as the maintenance and reporting of records. Waste classified
as environmentally hazardous include pesticide and radioactive wastes (no
disposal sites for radioactive wastes can be established, operated, or licensed
in the state). The statutes make specific provision for the establishment
of a chemical waste disposal site in the state, and provide for its regulation
by DEQ (see above).
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3.4.2 State Responses to December 18, 1978, Proposed Regulations
Under RCRA
In December, 1978, EPA published proposed regulations under Subtitle
C of the Resource Conservation and Recovery Act (RCRA). The specific
proposals concerned: "(1) the criteria for identifying and listing
hazardous wastes, identification methods and a hazardous waste list;
(2) standards applicable to generators of such waste for record keeping,
labeling, containerizing and using a transport manifest; and (3) performance
standards for hazardous waste management facilities." The proposed criteria
and standards are likely to effect pre-existing state-level hazardous
waste management regulations and programs, and to influence the form of"
such regulations and programs in those states which have not yet enacted
hazardous waste legislation comparable to RCRA.
Tennessee
State hazardous waste regulations are still in draft form,
incorporating changes based on recent public hearings. Latest draft is dated
November, 1978. After consideration of all public comments, further
changes may be made before regulations are finalized.
The November draft is reported to be similar to EPA's proposed
regulations for hazardous waste. With respect to fly ash bottom ash, and
other air pollution control wastes, the likelihood is that these wastes
will be considered as special cases. Such wastes are deemed to be of
relatively low hazard, but will be generated in sufficiently high volume
to merit special consideration. The state is trying to recognize these
kinds of wastes. "Utility wastes" are not defined in the Tennessee list
of hazardous wastes, as they are in the proposed federal regulations
pursuant to RCRA. However, fly ash, bottom ash, and scrubber sludges are
specifically identified as POL aitially hazardous.
The state intends to pursue federal funding although the test will
be whether the regulations as promulgated will be sufficiently stringent
to qualify.
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Pennsylvania
The State Department of Environmental Resources, Office of Solid
Wastes (OSW) anticipates that some changes will be forthcoming in the
Pennsylvania solid waste management regulations as a result of EPA's
proposed Subtitle C regulations. However, the changes in the Pennsylvania
regulations are as yet undeveloped, and it is too early to say what form
those changes may take.
The Pennsylvania solid waste program is not yet completely approved
for acceptance as a state solid waste management program. The OSW will
most likely pursue federal approval and funding. The recommendations of
the OSW in this matter have apparently not yet been acted on by the
Secretary of the Department or the Governor. The response to the Subtitle
C proposed regulations may have some bearing on the decision to pursue,
and timing for obtaining federal approval.
Utility wastes are now categorized as a solid (not hazardous) waste,
and are disposed at approved sites. Perhaps because of the existence of
apparently effective regulations and disposal sites, wastes generated by
coal-fired electric utilities are not now considered to be a problem in
the state.
Florida.
Existing environmental legislation in the state has designated an
Office of Hazardous Waste (OHW) under the Department of Environmental
Regulation. The present hazardous waste program is based on the case-by-
case determination of the hazardous nature of waste material. If a waste
is found to be hazardous, the legislation requires that the waste be
rendered innocuous and/or disposed of in a manner approved by the
Department.
The OHW and Department are proposing comprehensive hazardous waste
legislation in the next legislative session. Similar legislation was
proposed by the Department in the previous session, but was not acted on
by the legislature. To date, the proposed legislation has no sponsor,
and it appears premature to estimate chances for, or timing of, enactment.
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In its present form, OHW staff perceive the proposed legislation to
be comparable to RCRA definitions of, and criteria for, hazardous wastes.
It appears to be the intent of the Department to be independent, in the
sense of formulating legislation and regulations which address problems
peculiar to Florida. However, it appears likely, if the proposed program
is adopted, that the state will attempt to respond to federal guidelines
for hazardous waste under the solid waste management progam and hence
pursue federal funding.
It also appears likely that the state will adopt a position similar
to EPA, in the matter of special case wastes, e.g., utility (and in
Florida, gypsum) wastes. In its proposed form, the Florida Act is broad
enough to provide for interim, or special case, status for such wastes.
North Dakota
The basic plan of the state at this time is to assume administrative
responsibility of the Federal Hazardous Waste Program in North Dakota.
Enabling legislation has been passed, but the state presently has no
program. The legislation is vague, and there is no provision for civil
penalties. Utility wastes are now handled on a case-by-case basis.
There are five or six major power plants in the state; hence, utility
wastes are and will be a malor concern. The solid waste office is work-
ing with the state geological survey in studying disposal options and
also formulating responses to the federal proposal. The state solid
waste office does not anticipate a significant problem from the disposal
of fly ash and bottom ash, but does anticipate a potential problem in the
disposal of scrubber sludges.
Site specific criteria are and will be an important factor in
authorized disposal of these wastes.
North Dakota will pursue federal funding of its program, if in fact
the federal program is adopted. Adoption and implementation could take
one to two years, depending oh when the federal program is finalized.
Illinois
The proposed EPA regulations were considered by the Division of Land
and Noise (the state agency with solid waste management responsibility)
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to be more stringent than existing Illinois regulations. A specific
example of this federal stringency was noted with respect to the
heavy metals. Thus, for the hazardous waste criteria, there is a like-
lihood that the state will incorporate elements of the federal program.
Changes may also be forthcoming with respect to state standards for
hazardous waste generators and management facilities.
The position of the state regarding control of special wastes, (i.e.,
utility wastes) is apparently still unclear because of a question of
whether such wastes are, in fact, hazardous. Illinois regulations are
now compatible with certain requirements of the special waste standards
(i.e., the manifest system). Enabling legislation under which other
requirements could be met is on the books.
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3.5 Ocean Disposal Related
3.5.1 Statutory Base
The Marine Protection Research and Sanctuaries Act of 1972 (PL92-532)
is the basis for all domestic regulation of ocean dumping from vessels.
Several major provisions of this legislation are discussed below. Dis-
posal in the ocean via outfalls is regulated as a point source under the
NPDES permit program under the FWPCA.
Policy
Section 2(b) of the Act states,
"The Congress declares that it is the policy of the United States
to regulate the dumping of all types of materials into ocean
waters and to prevent or strictly limit the dumping into ocean
waters of any material that would adversely affect human health,
welfare, or amenities, or the marine environment, ecological
systems, or economic potentialities."
Mandatory Considerations in the Issuance of Permits
The Act states that no dumping may take place without a permit from
the Administrator of the EPA. Section 102(a) conditions the issuance of
such permits upon determination by the Administrator that, "...such
dumping will not unreasonably degrade or endanger human health, welfare,
or amenities, or the marine environment, ecological systems, or economic
potentialities." The specific review criteria to be used in reaching
these determinations are prescribed as follows:
"(A) The need for the proposed dumping.
(B) The effect of such Jumping on human health and welfare,
including economic, aesthetic, and recreational values.
(C) The effect of such dumping on fisheries resources, plankton,
fish, shellfish, wildlife, shore lines and beaches.
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(D) The effect of such dumping on marine ecosystems, particularly
with respect to -
(i) the transfer, concentration, and dispersion of such
material and its byproducts through biological,
physical and chemical processes,
(ii) potential changes in marine ecosystem diversity,
productivity, and stability, and
(iii) species and community population dynamics.
(E) The persistence and permanence of the effects of the dumping.
(F) The effect of dumping particular volumes and concentrations
of such materials.
(G) Appropriate locations and methods of disposal or recycling,
including land-based alternatives and the probable impact of
requiring use of such alternative locations or methods upon
considerations affecting the public interest.
(H) The effect on alternate uses of oceans, such as scientific
study, fishing, and other living resource exploitation, and
nonliving resource exploitation.
(I) In designating recommended sites, the Administrator shall
utilize wherever feasible locations beyond the edge of the
Continental Shelf."
Penalties
Section 105 of the Act provides for civil penalties of up to $50,000
for each violation of the Act. It further provides for criminal penalties
of not more than one year imprisonment, $50,000 fine, or both. Both the
government and private citizens are provided the opportunity to obtain
injunctive relief by Section 105 of the Act.
Preemption of Other Jurisdictions
Section 106(d) of the Act precludes state, interstate, or regional
authorities from adopting or enforcing any rules or regulations relating
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to ocean dumping. States may propose ocean dumping criteria to the EPA
Administrator who may adopt them if he wishes. Thus, unlike the regula-
tory climate surrounding land disposal alternatives, ocean disposal of
FGC wastes by vessels is the direct responsibility of only one agency,
the Federal EPA.
Establishment of Regulations
Section 108 of the Act gives the Administrator the authority to
establish such regulations as he deems appropriate. The existing and
possible future regulations are discussed below.
3.5.2 Administrative Regulations
Ocean dumping regulations were first promulgated by the EPA in
October 1973 to become 40 CFR 220-227. Subsequent amendments were adopted
during 1974 and 1977. Two sections of the ocean dumping regulations are
particularly relevant to the subject of this report. These are sections 227
and 228 which, respectively, cover the criteria for the evaluation of permit
applications for ocean dumping and the need for ocean dumping (227) and
the criteria for the management of disposal sites for ocean dumping (220).
Part 228 was added to the regulations in 1977, and major changes to
Part 227 took place during this same time frame. Changes in the following
aspects of the regulations are discussed below:
• Alternatives;
• Prohibited materials;
• Other factors limiting permissible concentrations;
• Monitoring requirements;
• Outfalls; and
• Artificial reefs.
3.5.3 Consideration of Alternatives
As of the 1977 amendments of the regulations, ocean dumping permit
applicants must demonstrate that there is no feasible alternative to
dumping. The following factors are included in determinations of the
need for ocean dumping versus available options:
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need for ocean dumping versus available options:
• degree of available treatment of the waste;
• available raw material and process changes;
• relative environmental impact and cost of ocean dumping and
other alternatives, including but not limited to landfill, well
injection, recycling, additional treatment, and storage; and
• irreversible or irretrievable consequences of the use of
alternatives to ocean disposal.
Determinations of the cost feasibility of available alternatives to ocean
disposal do not require that costs be competitive and take into account
environmental benefits as well.
3.5.4 Prohibited Materials
Under regulations in existence prior to 1977, eastern FGC wastes
could have been precluded from ocean disposal entirely on the basis of
the cadmium content of the solid phase of many of the materials containing
fly ash. This is because absolute limits existed on cadmium and mercury
concentrations in both the solid and liquid phases of all materials. These
limits were, for mercury, 1.5 ppm in the liquid phase of the waste and
0.75 ppm in the solid phase; and for cadmium, 3.0 ppm in the liquid
phase and 0.6 ppm in the solid phase.
Mercury and cadmium are no longer listed as prohibited materials in
the new regulations. This is perhaps the single most important change in
the regulations with respect to FGC wastes. These substances are now
listed as constituents prohibited as other than "trace contaminants",
with a new set of interim and anticipated ultimate means of determining
whether the "trace contaminant" definition applies. The current criterion
for mercury in the liquid phase of the wastes to be dumped in the ocean
is as follows:
"...mercury concentrations in the disposal site, after allowance
for initial mixing, may exceed the average normal ambient concen-
trations of mercury in ocean waters at or near the dumping site
which would be present in the absence of dumping, by not more than
50%..."
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A complementary criterion to be applied to all wastes, including
FGC wastes, is a series of bioassay tests. The object of these tests is
the identification of both acute and chronic toxicological impact poten-
tials of the waste and the potential for bioaccumulation of toxicants in
marine organisms as the result of exposure to the waste. The regulations
indicate that bioassay procedures for suspended particulate and solid
phases of waste materials are not sufficiently well developed to mandate
the use of such tests as a prerequisite for permit approval. Thus, in
the interim, while such procedures are being developed, the EPA personnel
responsible for the administration of ocean disposal programs (usually at
the regional level) are given a number of options for application review.
With respect to mercury and cadmium in the suspended particulate and
solid phases of wastes, the interim guidance is as follows.
Mercury and its compounds may be present in the solid phase of a
material in concentrations less than 0.75 mg/kg or less than 50% greater
than the average total mercury content in natural sediments of similar
characteristics at the disposal site. Cadmium and its compounds in solid
phase may be present in concentrations less than 0.6 mg/kg or, as with
mercury, less than 50% greater than the total cadmium content of the
natural sediments of similar characteristics at the disposal site. While
these numerical limits are identical to those in the previous regulation,
the wide range in "natural" sediment concentrations of mercury and cadmium
at disposal sites would ensure considerably greater flexibility than the
previous regulations.
3.5.5 Other Factors Limiting Permissible Concentrations
The 1977 amendments to the regulation changed the "mixing zone"
concept of previous regulatu is defining a "release zone" as a cylinder
whose outline is 100 meters from the perimeter of the conveyance engaged
in dumping.
In the mixing zone, no parameter may exceed .01 of a concentration
shown to be toxic to appropriate sensitive marine organisms over a 4-hour
period. Field data, mathematical modeling, or theoretical turbulent diffu-
sion relationships may be employed to determine the limits of the area of
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said toxicity. When no other means are feasible, it may be assumed for
purposes of calculation that the waste is evenly distributed through the
release zone over the upper 20 meters. These amendments all provide
greater flexibility in the permit process.
3.5.6 Monitoring Requirements
The new regulations contain a section 228 devoted to disposal site
management, including monitoring requirements and requirements for the
evaluation of the environmental impacts of disposal activity. A major
change in agency philosophy is reflected in these requirements. Pre-
viously, it appeared that permit applicants might be responsible for
baseline and trend assessment monitoring at disposal sites. However,
Part 228 clearly spells out that these responsibilities belong to the
federal government. Applicants' responsibilities are now confined to
special monitoring programs designed case by case to determine short-term
impacts of disposal activities.
Another important part of the regulation is the establishment of
criteria for the evaluation of disposal impacts. In summary, these
criteria establish a category of impacts (Category I) which, if identi-
fied at a disposal site, requires the EPA management authority to place
limitations on use of the site to reduce impacts to acceptable levels.
These Category I impacts include:
• statistically significant decrease in populations of valuable
commercial or recreational species or species essential to the
propagation of valuable commercial or recreational species;
• significant impairment of major uses of the site or adjacent
areas due to accumulations of solid waste material;
• adverse effects on taste or odor of valuable commercial or
recreational species as a result of disposal activities; or
• identification on a consistent basis of toxic concentrations
of any toxic waste, waste constituent or byproduct at levels
above normal ambient values outside the disposal site more
than four hours after disposal.
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These criteria leave open the possibility for accumulations of toxic
contaminants within the disposal site to a sufficient degree to impair
later harvest of transient (e.g., pelagic) species passing through the
site and becoming subsequently available through the food chain to man.
Because of the nature of finfish movements and, to a lesser extent, the
movements of other valued species (e.g., lobsters), there is a strong
likelihood that it would be impossible to detect consistently a direct
link between toxic accumulations in a disposal site and organisms
passing through that site, as required by the criteria.
3.6 Stability Related
3.6.1 Resource Conservation and Recovery Act of 1976 (PL94-580)
As discussed throughout this report, a key consideration under RCRA
is the identification of a waste as hazardous by EPA, Office of Solid
Waste. To date, FGC wastes have not been identified as hazardous, and
OSW has announced its intent to place whatever portion of these wastes
is declared to be hazardous in a special category subject to a limited
set of hazardous waste requirements. With respect to physical stability,
FGC wastes may constitute a potential hazard to personnel during disposal
operations due to liquefaction and loss of structural strength. As such,
this would be a concern of the Occupational Safety and Health Administra-
tion although they may work closely with EPA to establish protective
measures, which may include treatment, moisture content control, and
control of waste disposition within the landfill.
Other considerations for the stability of FGC wastes are stated in
two regulations published in the Solid Waste Disposal Regulations and
Guidelines (40 CFR 241); for completed sanitary landfills (§241.203-2(c) :
(1) that the integrity of the final cover shall not be disturbed by agri-
cultural cultivation, and (2) the recommendation that major structures
are not constructed on the site. Major structures built near a completed
land disposal site require design approval by a professional engineer.
(This regulation was written in response to the problem of gas production
from municipal and domestic wastes, not physical stability of FGC wastes.
However, it may be applied to the latter as well.) The possibilities of
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liquefaction and slumping of FGD sludges placed in fills are significant,
and either one could cause a threat to personnel safety or land quality.
The owner or operator of a landfill may screen the wastes to be used
in the fill by their exclusion in the permit. The criteria used in deter-
mining the acceptability of the waste are the hydrogeology, the chemical
and biological nature of the wastes, environmental and health effects,
and personnel safety (i241.201-1).
Specific approval by the responsible state authority for sludges
with a free moisture content is required because they are a "special
waste" (§241.201-2). Because complete dewatering of FGC wastes may not
be feasible, this approval implies that states will review most landfill
permits for sites planning to dispose of FGC wastes. The guidelines state
that the surface and side slopes of all landfills are to be specified in
the permit procedure to promote runoff without erosion and to minimize
infiltration (§241.204-3(a)). All fill material is to be compacted to
the smallest practicable volume (§241.210-1). Inclusion of FGC wastes,
which may settle, slump or liquefy, may very well cause alterations in
completed surface contour, slopes and runoff and drainage patterns.
Compaction of wastes may induce liquefaction of sludges, thereby
endangering personnel during disposal operations.
In a brief survey of the solid waste disposal regulations of several
states, the following criteria emerged. In Pennsylvania, FGD sludges may
be included with fly and bottom ash and slag in landfills if approved by
the Department of Environmental Resources (§75.37). This state requires
maintenance as long as necessary after completion of the landfill to
prevent health or pollution hazards or nuisances, to repair cracks,
fissures, slumps and slides, etc. In Illinois, the owner/operator shall
monitor and abate gas, water or settling problems within three years of
closure of the landfill. Most of the state regulations surveyed do not
mention FGC wastes by name, nor do they specify maintenance of final
contour of the landfill following completion.
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3.6.2 Surface Mining Control and Reclamation Act of 1977 (PL95-87)
The main objective of this statute is to protect the health and
safety of the public and to minimize damage to the environment. Section
515 establishes Environmental Performance Standards which set the "approx-
imate original contour" as a goal to aid in restoration of land quality.
Regulations promulgated as of this writing include the interim program
published in the Federal Register on December 13, 1977, and a permanent
regulatory program proposed September 18, 1978 (Federal Register). Key
issues which are as yet unresolved: Can FGC wastes be incorporated as
backfill material during reclamation operations at surface mines? If -
so, will they be classified as a "toxic-forming waste" (or hazardous
material) or as an "acid-forming material" if high in sulfur compounds.
Backfill materials referred to in the regulations are limited to
spoil, overburden and coal processing wastes. In §715.14(3) the use of
wastes from other activities outside the permit area is covered but the
wording is unspecific as to the types of wastes that would be permissible;
§817.20(c), which deals with coal processing wastes, defines "materials
from other operations" to exclude non-mining activities.
If future regulations are promulgated which allow the incorporation
of FGC wastes in backfilled areas of reclaimed surface mines, interim
regulations contain provisions which would have a direct bearing on
physical stability, especially those which deal with achievement of
land quality functions; specifically:
§784.19 Subsidence Control Plans which "shall describe the
subsidence control to be used to achieve compliance
with the requirements of subchapter K (Environmental
Performance standards)."
§715.14(J) "Before waste materials...from other activities outside
(3)
the permit area...are used for fill material, it must
be demonstrated to the regulatory authority by hydro-
geologic means and chemical and physical analyses that
use of these materials will not... cause instability in
the backfilled area.
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§715.14(b) Deals with the situation where modification of the
original slope has been approved by the regulatory
authority. "The permittee shall...be required to
(ii) backfill and grade to the most moderate slope...
as is necessary to insure stability."
§715.17(J) Covers mining in alluvial valley floors west of the
hundredth meridian west longitude. "Surface coal
mining operations conducted in or adjacent to all
valley floors shall...preserve the essential hydro-
logic functions... The characteristics...to be con-
sidered include: (v) configuration and stability of
the land surface in the flood plain and adjacent low
terraces in alluvial valley floors as they allow or
facilitate irrigation of the flood waters or subirri-
gation and maintaining erosional equilibrium;
(vi) moisture holding capacity of the soils within
the alluvial valley floors and physical and chemical
characteristics of the subsoils which provide for
sustained growth or cover through dry months."
The case of acid- or toxic-forming waste materials as defined in
§710.5 is dealt with in §715.14(j)(1) :
"Any acid-forming, toxic-forming or combustible
materials identified by the regulatory authority that
are exposed, used or produced during mining shall be
covered with a minimum of four feet of non-toxic and
noncombustible materials...(2) Backfill materials shall
be selectively placed and compacted wherever necessary...
to ensure the stability of the backfill materials."
This requirement also applies in §717.14, the backfilling and grading of
road cuts, mine entry area cuts, and other surface work areas.
Section 716.7(e)(4) covers the case of reclamation of prime
agricultural land which is under the jurisdiction of the Department of
Agriculture. Given the present uncertain status of FGC wastes with
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regard to their hazardous nature, it is probable that the Department of
Agriculture would prohibit the use of such materials in any manner in
such designated areas (SCS Engineers, 1977).
An additional stability consideration is stated in §784.15, Dams
and Impoundments, subsection (b)(x): "Slope stability analyses will be
required for existing and proposed embankment slopes for construction
and long-term conditions... Consideration must be given to the possibi-
lity of landslides into the impoundment..." Another regulation which
deals with impoundments, which are often used to contain FGC sludges,
is §715.18(a): "No waste material shall be used in or impounded by
existing or new dams without the approval of the regulatory authority."
This regulation is followed by extensive construction requirements
which include periodic inspections of dams and impoundments.
If FGC wastes are determined to be legitimate backfill materials,
then the major restrictions in their use will be compliance with the
above-mentioned regulations and also with performance standards aimed
at achieving the "approximate original contour." Subsidence, whether
through liquefaction or consolidation, may cause violations of the
contour requirement over time, and the threat of landslides may be
realized if proper restrictions and guidelines are not developed. At
present, the regulatory program does not address this issue although
the foundation has been laid to implement the use of FGC wastes in
mine reclamation.
3.6.3 Federal Coal Mine Health and Safety Act of 1969 (PL91-173)
This statute focuses primarily on miner safety while on the mine
property, with respect to disease and safety. Accident prevention is
stressed; for example, storage of materials, usage of equipment, mining
engineering, and air quality. The latter include such accidents as gas
build-up, explosions and the cumulative health effects of inhalation of
fugitive dust and other particulates (e.g., black lung).
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The disposal scenarios described in Section 2 involve disposal in
an abandoned portion of an underground mine behind an engineered bulk-
head. Therefore underground mining disposal of FGC wastes is not an
occupational safety issue for miners if performed correctly.
3.6.4 Occupational Safety and Health Act of 1970 (PL91-596)
The prime responsibility of OSHA covers worker safety, as does
the CMHSA. In 1974, a memorandum of understanding was published between
MESA and OSHA (Federal Register, July 26, 1974) which established the
exclusive authority of the former on mine property. OSHA jurisdiction
extends to the storage and handling of materials at power plant sites
and at landfills. There are safety problems in these circumstances
where FGC wastes are used to support a load (e.g., in a landfill cell)
which could endanger personnel if loss of structural strength occurred.
Liquefaction during materials storage is not dangerous unless the
regaining wall (embankment or container) fails and personnel may be
flooded. Because liquefied sludges may flow almost as fast as water,
this could be a hazard. During transportation, vibrations may cause
liquefaction and generate noticeable volumes of interstitial waters.
The OSHA regulation 29CFR 1910.176(d) calls for the provision of
"proper drainage" during storage and handling but not during transporta-
tion. OSHA would have authority over the reclamation of abandoned
mines because no mining activities are taking place, therefore, the
workers would not be subject to MESA authority.
3.6.5 Dam Inspection Act of 1972 (PL92-367)
This statute calls for the inspection of all non-federal dams
over 25 feet in height, and impounding, at maximum water storage eleva-
tions, at least 50 acre-feet. A national inventory, conducted by the
Corps, of Engineers [52], included "approximately 49,000 dams, most of
which were privately owned. Of these, approximately 9,000 were identified
as high-hazard, meaning in the event of a failure, there would be sub-
stantial loss of life and property". An announcement of the Federal
Program for Inspection of Non-Federal Dams was announced by the White
House in December 1977, and funds were appropriated for the inspection
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of the 9,000 high-hazard dams. Findings of each inspection are written
up and the report is sent to the owner/operator of the dam or impound-
ment and to the governor of the state with recommendations as to the
safety of the dam. It appears that any impoundment meeting the height
and capacity criteria, which is located in a high-hazard area, as
defined above, would be inspected regardless of the material it con-
tained.
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3.7 Land Use Related
3.7.1 Overview
From the broadest perspective, the key impact issues concerning land
use are those directly related to the regulation of the location, oper-
ation and final disposition of land-based disposal sites. The Resource
Conservation and Recovery Act of 1976 is the principal legislation govern-
ing land disposal of waste material.
The classification of FGC wastes remains a focal issue because of the
implications this classification poses for site selection, operation and
closure, Furthermore, while speculative at this time, the designation
of two types of solid wastes by RCRA may ultimately alter the manner in
which some local governments control the location of waste disposal sites
within their jurisdiction. These issues will be addressed in the specific
discussion of RCRA-related regulation.
The Surface Mining Control and Reclamation Act of 1977 is important
because coal mines represent a disposal option. Further, this legislation
was designed to regulate certain types of land use. As discussed below,
the degree to which specific regulation promulgated as a result of this
Act apply to FGC waste disposal, is not totally clear.
From conversations with OSM and background materials included with
various regulations, it seems likely that EPA and OSM may attempt coordina-
tion of efforts on land disposal of waste material. The draft and/or
untried nature of most regulatory programs that can be directed at solid
waste disposal confuses a number of issues, as noted below.
3.7.2 "Resource Conservation and Recovery Act of 1976", Associated
Proposed Regulations, and State and Local Regulations
As discussed in 6.2.2, the key regulatory issue surrounding the land
disposal* of FGC wastes due to the Resource Conservation and Recovery
*"Disposal" as defined in RCRA includes: "...the discharge, deposit, in-
jection dumping, spilling, or placing of any solid waste into or on any
land or water so that such solid waste or hazardous waste or any constituent
thereof may enter the environment or be emitted into the air or discharged
into any waters, including groundwaters."
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Act is the ultimate designation of these sludges as "hazardous" or "non-
hazardous." The discussion below ignores this issue other than to address
the requirements for disposal under either designation.
3.7.1.1 "Standards Applicable to Owners and Operators of Hazardous
Waste Treatment and Disposal Facilities" (Proposed December 18. 19781)
RCRA provides ultimate federal regulatory authority over hazardous
waste disposal, although states may administer federally approved programs.
Key land use issues indicated by the proposed standards were derived from
discussions of:
• General site selection*
• Technical requirements for closure and long-term care ,
• Landfills»
• Surface impoundments >
• Basins, and
• Landfarms•
Overall, there are significant financial liability provisions and
closure costs to ensure environmentally sound disposal of wastes. Key
elements of the issues listed above are:
General Site Selection - Most of the mandatory standards are con-
cerned with removal from and avoidance of public areas and environmentally
sensitive areas. These latter include wetlands, permafrost areas, critical
habitats, etc. with some excepted cases.
Closure and Long Term Care - This section makes mandatory the require-
ment that the closed site land is "amenable to some productive use."
Closure procedures must insure that waste cannot be contacted by human
or animal life and that discharges of waste harmful to health or the
environment do not occur. The type of cover (e.g., one that minimizes
or eliminates infiltration of water, supports vegetation, prevent sub-
limation, etc.) is one such requirement. For landfills or other sites
where waste remain, future use cannot include residential, agricultural,
or other use which could disturb the "integrity" of the closed site.
Landfills. Surface Impoundments, and Basins - These must be located
and operated to prevent direct contact with surface water, and the borders
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of the site must be at least 150 meters from a water supply. The landfill
must be at least 1.5 meters above the historically high water table. These
requirements place constraints on location of sites and thus may be con-
sidered land use issues.
This discussion has only highlighted specific requirements of the
standards for disposal of hazardous materials. Should some FGC wastes be
designated hazardous, the main land use issue appears to be whether or
not sufficient facilities can be found for the traditional disposal of the
volumes anticipated. One question is how the designation "hazardous"
will affect the location of sites. In some parts of the country, there
is difficulty in locating sites even for the disposal of municipal refuse.
In more highly congested areas, traditional dumps have often been located
at or near less desirable development land (e.g., wetlands). There is
also the economic question of what increase in cost the specific new
requirements represent, and how much of an impact that would have on
operators, especially those in the private sector. It would seen that
this would compound the site location difficulties and problems of waste
volume. These are in addition to specific issues raised by the legal
requirements listed above.
3.7.2.2 "Criteria for Classification of Solid Waste Disposal facilities"
(Proposed February 6^ 1978)
Proposed "Criteria for Classification of Solid Waste Disposal Facilities"
were published in February 1978 while the final criteria have not been
published to date. The criteria listed must be followed for the location,
design, construction, operation, completion, and maintenance of disposal
facilities if they are to be classified as posing "..* no reasonable pro-
bability of adverse effects on health, safety, or the environment."
Key land use issues covered by these criteria include protection of
environmentally sensitive areas, such as wetlands, critical habitats,
permafrost regions, and sole source aquifers. Restrictions relevant to land
applications of waste material prevent spread of disease and contamination
and ensure safety. The major issue for the disposal of non-hazardous
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materials is the eventual adoption by all the states of these or similarly
protective criteria. In Section 3.3 state existing regulatory programs
are reviewed, all of which were developed prior to RCRA criteria or
guidelines.
3.7.2.3 Title 40. Part 256 - "Guidelines for Development and Imple-
mentation of State Solid Waste Management Plans"
The guidelines for approval of state plans are still in draft form,
thus a number of changes could occur before the final guidelines are pub-
lished. A key issue can be identified from these draft guidelines and
the discussion of EPA's interpretation of their intent (included as back-
ground with the draft). First of all, it is noted that while it is not
the intent of the guidelines to supplant private sector initiatives in
solid waste disposal, some state initiatives may also be needed. This
appears, in part, as a recognition of the difficulty in locating disposal
sites in some regions. The EPA (in the discussion preceeding the guide-
lines) recognizes the local or regional role in site selction and/or
acquisition. However, it is an explicit intent that states explore options
for more direct control over siting and facility development. Of particular
interest is the following quotation (page 23 of the draft):
"EPA invites comment on methods for the state to obtain greater
control over facility acquisition. Such methods could include
obtaining the authority to override local zoning laws or to
contract directly for facilities and services requiring facility
permits to conform to regional plans developed under the state
plan, or instituting a public utility agency to regulate the
supply of services."
It is difficult to predict the outcome of such suggested control.
While sufficient sites for disposal remains a very important issue, it
does not appear that it can be dealt with other than to recognize its
significance and to follow the progress of state plan development.
An additional issue was noted in EPA's interpretation of the intent
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of these guidelines. It suggests coordination with the Department of
the Interior for an inventory of mining wastes which would include aban-
doned lands. It is suggested that this coordination might also increase
the use of sludges (unspecified) in reclamation of abandoned mining lands,
noting that DOI will provide states with funding for reclamation once they
have approved enforcement programs for activating sites. It appears
that OSW and the DOI are considering abandoned locations for the disposal
of sludge (with possible financial support).
3.7.2.4 State and Local Issues
It is evident that state solid waste plans will probably
undergo at least some modification in those states applying for
EPA approval in light to the final guidelines established by RCRA.
The degree of modification will depend on the differences between
existing state plans and interpretation of the requirements estab-
lished by federal criteria and guidelines (and yet to be finalized).
Location of land disposal sites, as a land use issue, is typically a
decision left to local prerogatives. Where zoning exists, landfills can
be included as "conditional uses" making them subject to review by some
municipal authority, while, in some cases, "garbage dumping" or even
open dumping is prohibited. Many local communities also have performance
standards: usually a general list prohibiting uses that produce noxious
odors, noise, air pollution, water pollution, etc., (sometimes at a
specific level) with the determination of compliance left to some muni-
cipal authority. Where sanitary landfills are included as a conditional
use, local requirements concerning buffer zones and access, as well as
final cover and reclamation may also be listed. These can be in addition
to existing state permitting requirements or regulations where the latter
exist.
As with other levels of disposal regulation, the major issue surround-
ing local regulation of landfall sites is the local availability of sufficient
sites for the land disposal of FGC Wastes. With site designation left
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under local control, local citizen pressure, competition from other more
lucrative land uses, historical precedent or practices, and land availa-
bility could all be important. Evolving state authority over the loca-
tion of sufficient disposal capacity for the state, if implemented, could
alter the significance of this issue somewhat, but this would represent
a new role for state government. Furthermore, it would appear that
designation of FGC wastes as hazardous would compound the problem from
the standpoint of local acceptance as well as the earlier mentioned eco-
nomic standpoint.
3.7.3 Surface Mining Control and Reclamation Act of 1977 and Associated
Regulations
The Surface Mining Control and Reclamation Act is relevant because
surface and underground mines are being considered as options for FGC
waste disposal. SMCRA can be viewed as a land use law — in essence, it
is directed toward preventing practices that (in addition to posing a
threat to human health) degrade environmental quality. It establishes,
for most situations, requirements for reclamation of mined land to its
pre-mining capabilities. The Act itself does not prohibit or allow for
the disposal of wastes generated by other than mining practices. For the
purpose of identifying land use impact issues related to this law, it is
•
assumed by the authors of this report that disposal of sludge wastes in
surface or underground mines would have to meet the objectives of the Act
and the requirements of specific regulations.
The Act includes performance standards which provide the framework
for promulgation of a minimum set of regulations. Interim regulations
are presently in effect and the permanent regulatory program was proposed
on September 18, 1978, Federal Register. The standards include operational
procedures that are directed toward the protecton of surface and ground-
water quality and quantity, and control of erosion and air pollution.
They are also directed at reclamation procedures that, in addition to
providing the above protection and/or control, are aimed at returning
mined land to a condition capable of supporting the pre-mining or "better"
use.
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The term "wastes," without modifiers, is not defined in the Act.
There are a number of performance standards that could, if interpreted
literally, be applied directly to a number of disposal options for FGC
sludges in or at the site of surface or underground mines. These include:
• The stabilization of all surface areas affected by reclamation
to effectively control erosion, and air and water pollution;
• The treatment, burial, and compaction or other form of disposal
of other debris, acid forming materials and toxic materials* in
a manner that would prevent contamination of ground or surface
waters; and
• The surface disposal of wastes in waste areas (other than
excavations) only when they can and will be stabilized and
revegetated.
If the feasibility of sludge disposal in surface or underground mines
is assumed, the implications of the following standards (reflecting
objectives) should be considered:
• The approximate original contour of the disturbed land must be
restored (with exceptions) and stability ensured.
• The reclaimed area must be revegetated with a diverse permanent
vegetative cover of the same seasonal variety native to the area
(there are alternate use exceptions).
*Two definitions of toxic materials are found in the Surface Mining En-
forcement Provisions.
"Toxic-forming materials means earth materials or wastes which, if acted
upon by air, water, weathering, or microbiological processes, are likely
to produce chemical or physical conditions in soils or water that are
detrimental to biota or uses of water."
"Toxic-mine drainage means water that is discharged from active or aban-
doned mines and other areas affected by coal mining operations and which
contains a substance which through chemical action or physical effects
is likely to kill, injure, or impair biota commonly present in the area
that might be exposed to it."
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• For "prime agricultural" lands, if replaced top soil horizons are
altered, they must be equally or more favorable for plant growth/
productivity (compared to local "reference" areas). There are also
special restrictions for mining (and reclamation) in alluvial valley fl
• Acid or other toxic drainage to surface or groundwater systems must
be avoided by treatment of drainage or of preventing contact with
toxic materials.
Interestingly, it appears that the standards for permanent water
impoundments, if interpreted literally, could include the ponding type
disposal option for FGC wastes.
As part of the permitting requirements, mining operators must prepare
mining and reclamation plans that outline procedures to be taken for com-
pliance with this law. In addition, a performance bond must be posted as
insurance against non-compliance. The implications of sludge waste disposal
in adding risks (if any) to the operator, especially where acid mine
drainage is not a problem, are not clear. It would appear that problems
arising from this additional liability could range from simple procedural
ones, to rejection of sludge disposal by the operator. Discussion with
the OSM has indicated that they believe the operator would remain liable although
positions on waste disposal in general have not yet been established.
3.7.3.1 Interim Regulations - Final Form
The interim regulatory program defines "wastes" restricting that
term to "earth materials" associated with the coal mining/cleaning pro-
cess. This would, therefore, not include FGC material. However, a
single overall statement does encompass disposal of materials other than
the defined wastes, this would allow for the use of FGC wastes as fill
under the following provision:
that it "...must be demonstrated to the regulatory authority by
hydrogeological means and chemical and physical analyses that use
of these materials will not adversely affect water quality, water
flow and vegetation; will not present hazards to public health and
safety and will not cause instability in the backfilled area."
(715.14(J))
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In conversation with OSM, it was indicated that the above quoted
overall statement was included as an "umbrella" to cover contingencies
not yet fully considered. The indication was that a series of "position
papers" would follow after the full regulatory program is in effect.
The interim enforcement provisions, now in effect, provide perfor-
mance standards for both mining operations and reclamation. Below is
a brief outline of reclamation performance standards which would appear
to be most directly applicable to disposal of sludge material in surface
or underground mines. It must be emphasized that OSM apparently intends
to evaluate, establish, and clarify their position on requirements related
to such disposal at a later date. Thus, the applicability of some stand-
ards remains unclear.
1. Post-Mining Use of Land. Disturbed areas must be restored to a
condition capable of supporting pre-mining use; or "higher or better" uses
where the proposed alternative, among other requirements, is designed
to conform with applicable standards for adequate stability, drainage,
vegetative cover, and will not pose any actual or probable threat to
waterflow reduction or pollution. The main issue here is whether or not
disposal of FGC wastes would have an affect on the standards.
2. Backfilling and Grading. All spoil material must be backfilled
and compacted where it is necessary to ensure stability, or to prevent
leaching of toxic material, and then graded. There are also specific
requirements for grading of slopes (with exceptions for high and low over-
burden ratios. The latter may need to be considered for FGC waste disposal)
Several additional standards are included in this section:
(a) Permanent Impoundments. Impoundments may not be constructed
on top of areas where excess materials are disposed. It is
yet unclear whether or not this would include "sludge as fill"
material, although later in this section it requires that all
toxic materials have to be covered so that there is no leaching,
etc.
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(b) Covering Coal and Acid-Forming, Toxic-Forming, CombustibleT and
Other Waste Materials. All material remaining after mining that
might be toxic-forming, etc., must be covered by a minimum of
four feet of non-toxic, non-combustible material. It necessary
such material has to be treated to neutralize the toxicity in
order to prevent water pollution or to minimize adverse affects
on plant growth, land use, etc. In addition, the standards
require the toxic forming material shall not be buried or stored
near a drainage course so that it would pose a threat of water
pollution.
(c) Stabilization. Backfilled materials have to be either placed or
compacted (if necessary) to prevent the leaching of toxic-forming
materials into surface or ground waters.
(d) Use of Waste Materials as Fill. This paragraph was cited in the
discussion above as being the statement that covered the use of
wastes other than mining wastes as fill, provided it could be
demonstrated that no adverse affects would occur. It is this
overall statement that is pending further definition by the
Office of Surface Mining.
3. Disposal of Spoil and Waste Materials in Areas Other than Mine
Workings or Excavations. There are specific requirements for how spoil
materials or waste materials are to be disposed of. However-, it is not
clear that these could apply to wastes other than mining wastes. These
requirements are specifically ones for ensuring stability and prevention
of leachate to subsurface waters, etc. Evidently, additional standards
for this type of waste disposal are included in the draft regulations that
have not yet been received in-house.
4. Revegetation. The major requirement of this section is that
vegetative cover will be able to stabilize surfaces and prevent erosion.
In addition, revegative cover must be diverse, permanent, and of species
native to the area. These standards are general with special ones applied
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to prime agricultural land. In the latter case, there are very specific
requirements for top soil handling, etc.
There is an entire section of special performance standards for such
situations as prime farmland, mountain top removal, etc. Most of these
are operational requirements and as they are special situations, it is
not clear how much, if at all, they would apply to FGC waste disposal. It
is questioned whether prime farmlands cou?d be considered at all.
There is also a section of underground mining performance standards.
A review of this section indicates that standards are very similar to
those listed above for surface mining. These standards are directed at
surface operations for underground mines, and additional standards are
forthcoming. The standards do include covering of toxic-forming materials
and backfilling and grading, protection with hydraulic systems, etc.
In summary, two major land use issues can be derived from this dis-
cussion of the Surface Mining Control and Reclamation Act and subsequent
regulations. The first is the degree to which the requirements of the Act
and regulations apply to FGC waste disposal at a mining site. As that
issue has not yet been resolved by the Office of Surface Mining, the
second issue is the degree to which disposal of sludges in mined areas
would prevent compliance with the existing performance standards for
reclamation.
3.7.3.2 Permanent Regulatory Program
The interim regulations that are presently in effect can be administered
by states under their existing permit programs. Once, the full regulatory
program is in effect, however, states will have to, in many cases, revise
their surface mining rules and regulations to comply with the requirements
of the complete federal regulatory program in order to be approved.
Additional land use related requirements that might affect disposal
of FGC wastes are not specifically included (although there are additional
air and water requirements that will be dealt with elsewhere). Certain
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requirements of the final regulatory program are worth noting, however
mostly because they do pertain to either special regulations for certain
mining sites or indirectly to economic requirements of mining operators.
Extensive requirements will exist for operators before a permit will
be granted. The most pertinent ones surround the requirement for a re-
clamation plan. Such requirements include the plan for controlling the
surface and groundwater drainage, plan for treatment where it is
required, a plan for restoration of water recharge capacity where
required, a plan for collection and reporting of ground and surface
water quality and quantity data, a plan for a description of measures
that will be taken to ensure that debris, acid-forming and toxic-forming
materials will be disposed of in accordance with the Act, and finally,
an estimate of the cost of reclamation. This latter requirement is im-
portant because a bond has to be posted to cover liability for the area of
land affected by surface coal mining and reclamation operations under the
permit (bonds are posted in one-year increments). These requirements would
appear to make it essential to understand the implications of waste dis-
posal in terms of operator liability.
In the section, "Disposal of Non-Coal Wastes", of the discussion report
of the proposed permanent rules (43FR41767), the following quotation is
relevant:
"Another alternative which was reviewed concerned the utilization
of surface mines for approved, centrally located sites for dis-
posal of non-coal wastes by other mines, other industries, and
even municipalities, in are?s where suitable, physiographic and
hydrologic conditions did not provide sufficient alternative
disposal sites. The proposed regulations do not specifically
address this issue, and public comment is solicited on the
appropriateness of opening mine sites to outsiders for dumping."
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A similar approach is suggested for the use of deep mines as disposal
sites with the comment added that OSM is soliciting suggestions on the
appropriateness of underground mines for disposal, as well as any dif-
ferences which should be considered between underground and surface mine
workings.
3.7.4 Land Use Considerations under State Solid Waste Management
Regulations
A telephone survey of the ten EPA regions resulted in the selection
of eight state solid waste regulations for review. As surface water,
groundwater and stability considerations have been dealt with in Sections
3.2, 3.3 and 3.4, this review will focus only on land use considerations.
The following review focuses on three types of land use considerations:
• The types of regulatory control,
• The disposal site location requirements, and
• Closure and post-closure requirements.
While specific examples of types of regulation from specific states
are cited, they are intended to be exemplary only. In other words, such
examples are not intended to represent the best approaches, or the only
approaches to these various land use-related considerations. However, on the
whole, examples were chosen to illustrate the more restrictive requirements.
1. Types of Regulatory Control. Review of selected state solid
waste management legislation indicates that for non-hazardous waste
material criteria or standards for the handling, disposal, etc., are
established at the state level. However, solid waste management plans
are typically developed at a more local level (regional, county, etc.)
with variable state involvement. Several approaches are illustrative.
• Under the Texas Solid Waste Disposal Act (Ch. 405, Art 4477-7
1969 as amended) every county in the state has solid waste manage-
ment powers and may develop county solid waste plans. Under the
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Texas Municipal Solid Waste Management Regulations (1975. amended
1977), the Department of Health Resources policy on land use is
given, "...regulations shall be prepared incorporating statements
which will guide applicants for solid waste permits toward the
selection of sites remote from public concern and encourage in-
novative management procedures such as recycling, land improvement
and the generation of energy. Further, the intention of the
applicant shall be directed to the absolute necessity for land use
compatibility of solid waste facilities with other land uses
within the impact area of the proposed site." (Section A-5.) There
is a note that the Department supports the decision that land
use matters be managed by local government.
• Under Chapter 75 of the Solid Waste Management Rules and Regulations
(Title 2, Ch. 75, 1977), of the State of Pennsylvania, municipa-
lities are to submit plans to the Department of Environmental Re-
sources, including (a) resolution drafts and drafts of ordinances
contracts, and agreements that indicate the plan can be implemented
and (b) a summary of solid waste problems including future con-
straints expected to influence either solid waste systems such as
available land, physical limitations, transport facilities, pol-
lution regulations, or land use regulations, etc.
• The New Jersey Solid Waste Laws (Ch. 39, 1970 as amended), esta-
blish within the State Department of Environmental Protection, the
authority to formulate and promulgate rules and regulations con-
cerning solid waste collection and disposal. All the counties
and the 14 community Hackensack Meadowlands District in New
Jersey are designated solid waste management districts and
develop their own waste management plans. Significantly, in
cases where a district has established that there are insuffi-
cient existing or available sites for solid waste facilities
and that there are difficulties in finding available space,
state level authority for intervention in disposal site loca-
tion is authorized by this act.
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As with federal regulations, state level control over hazardous waste
disposal is far more stringent than for non-hazardous waste. The degree
of state level control varied among the state regulations reviewed, as
illustrated in the two examples below. The second example appears to
be a far more typical approach.
• In the State of Oregon, environmentally hazardous waste cannot be
disposed of on any land other than real property owned by- the State
of Oregon, and designated as a disposal site. Under the Oregon
Solid Waste Control Law (Ch. 409, 1969, as amended, Section
459.580) the licensee of a hazardous waste disposal site must
deed to the state (for reimbursement) the portion of the site in
or upon which hazardous wastes have been disposed of as a con-
dition of the issuance of a license.
• Under Texas Solid Waste Disposal Act (op cit); The State Solid Waste
Agency has the responsibility to control all aspects of industrial
solid waste collection, handling, storage, and disposal. Where
both municipal and industrial solid wastes are involved, then the
agency has jurisdiction over the activity.
2. Disposal Location Requirements. Review of selected state
solid waste management legislation and regulations indicates that criteria
and/or standards (especially for hazardous material) are established at
state level, but approaches vary. Two approaches are illustrated below:
• The State of California has published a manual for disposal site
design.* Essentially, this manual establishes classifications of
wastes by impact potential and classification of disposal sites
by their ability to attenuate such impacts. If FGC wastes were
classified as "Group I" wastes, their disposal would have to be at
"Class I" sites: those that provide maximum protection from leaching
*Waste Discharge Requirements for Non-sewerable Waste Disposal to Land,
California State Water Resources Control Board, January 1978.
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and certain forms of runoff problems through occurring geological
conditions.
• In a draft of Tennessee's Hazardous Waste Management Regulations
(August, 1978), site permit applications are very specific. Such
requirements include contour maps that show land use patterns and
zoning within 2,000 feet of the facility, a preliminary geologic
and hydrologic review of the area within 5,000 feet of the site
the life of the facility, the chemical and physical characteristics
of the waste to be disposed of as well as transformations and/or
residuals, and an outline indicating the plan of construction
sequence for the proposed site, and closure plan.
The "hazardous" site requirements or permit requirements are used
as examples as they are, in general, far more specific than those for
non-hazardous waste disposal facilities. The latter, would typically be
regulated by local codes, which generally contain "nuisance regulations,"
but in some cases include environmental performance criteria borrowed
from state guidelines.
3. Closure/Post-Closure Requirements. Minimum standards for site
closure are typically included in the selected regulations reviewed. These
include final slope or stabilization requiiements, cover and revegetation
requirements for all types of sites. Monitoring, treatment of runoff or
its accommodation by surface drainage, maintenance of liners, and require-
ments for underground drainage, exemplify requirements for hazardous waste
disposal sites found in a number of state regulatory programs. A number
of states have also established bond requirements as insurance that clos
requirements are met and long-term maintenance can be required in some
states for certain types of disposal situations.
Of the regulations reviewed, only one state, Kansas, established post-
closure requirements for site land use planning, and even here this was fn
"'•
hazardous solid waste disposal sites only. The Kansas regulatory program
(Article 29) establishes requirements whereby restrictive convenants may
be made of the facility after closure, specify the period for which
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restrictive covenants apply, or describe modifications that could be
Initiated by property owners so that other land uses could be established.
It is possible that understanding of the characteristics (i.e., risk-
potential) of re-use of hazardous waste disposal sites would make such
requirements infeasible for hazardous waste facilities. In fact, similar
language is not used in the hazardous waste regulations for Kansas.
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3.8 Air Related
Activities associated with the handling and transport of FGC wastes
accelerate drying (solids content ranges from less than 10% to 60%) and
increase the probability for the creation of fugitive air emissions, i.e.
suspended particulates which are not emitted through a stack. It is these
emissions which have become a concern of regulatory agencies.
As discussed throughout this section under RCRA, FGC wastes are
provsionally considered "special wastes". However, it appears likely
that they will not all be subject to the full set of hazardous waste
regulations, particularly the design standards of Section 3004.
Section 1006 of RCRA directs EPA to integrate to the maximum extent
practicable all provisions of RCRA with appropriate provisions of the
other Acts of Congress which give EPA regulatory authority. One of the
ways EPA has chosen to integrate RCRA with the Safe Drinking Water
Act (SDWA), the Clean Air Act (CAA), and the Clean Water Act (CWA) is
through the use of Human Health and Environmental Standards. Each of
them - the groundwater, surface water, and air standard - establishes an
overriding standard for treatment, storage, and disposal facilities by
incorporating relevant limitations established under those acts.
Since the primary pollutant generated by FGC wastes is suspended particu-
lates, the Clean Air Act as amended (CAA) would apply.
Prior to 1978, all dust generated in earth-moving and materials
handling during FGC waste disposal would have been considered fugitive
dust emissions. However, the prevention of significant deterioration
(PSD) regulations established in 1978 by EPA under the Clean Air Act of
1977 clearly defines fugitive dust as consisting of "particles of native
soil which is uncontaminated by pollutants resulting from industrial
activity." Particles so defined are not subject to PSD regulations in
FGC disposal activity. This implies that only the fugitive emissions of
FGC wastes, per se, and any dust generated in the handling of aggregates
used in FGC waste treatment,will be considered in PSD increment deter-
mination for new waste handling, treatment, and disposal facilities.
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However, if these activities occur on the utility site, they may be
reviewed in the larger context inclusive of stack emission from the plant
itself. The (PSD) regulation applies only to particulate and sulfur
dioxide pollutants at this time and establishes the area classifications
and limits for increases (increments) in concentrations of these pollutants
above existing levels as shown in Table 3.6.
Class II PSD provisions of the Clean *\ir Act Amendments apply to
most areas of the country designated by states as being in attainment
of National Ambient Air Quality Standards, except for areas initially
designated Class I. Numerous permit requirements are now mandated
by law for certain modified stationary sources (greater than 100 tons
per year (tpy) potential uncontrolled emission rate).
Permit review needs are considered according to the level of
technical review needed; PSD regulations allow for three levels of
permit evaluation. Level I permit applications are sources which are
not subject to non-attainment or PSD review because the emission rate
is below the statutory cutoffs or reductions in emissions are expected.
Applicants are subject to State Implementation Plan (SIP) and/or New
Source Performance Standards (NSPS) review. New source applicants
deemed subject to non-attainment or PSD review are made aware of
measures that would eliminate non-attainment or PSD review. Such
measures could include site relocation, sulfur restrictions in fuel,
emission standards tighter than the SIP or NSPS and process equipment
changes that are less polluting, among others.
Finally, Level III permit applications, where predicted ambient air
concentrations are significant after Level II screening, are referred for
review by dispersion modeling. If the modeling indicates that particulate
emissions, for example, will cause or contribute to ambient air concen-
trations which exceed the maximum allowable increases for Class I areas,
the state may still issue a permit. However, the emitting facility must
give assurances that its emissions together with all other sources will
not exceed the maximum allowable increases over baseline concentrations
stipulated for Class II areas for particulates.
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Table 3.6
PSD Limits on Increases-in Pollutant Levels
(yg/m )
Basis: All numbers in microgram per cubic meters
so2
TSP
Annual
24-Hour
3-Hour
Annual
24-Hour
Fe
Class I
2
5
25
5
10
rmitted Incre
Class 11
20
91
512
19
37
ments
NAAQS
T*—
Class III NAAOS
40
182
700
37
75
80
365
1300(s)
75 60(s)
260 150(s)
Note: All 24- and 3-hour values may be exceeded
once per year.
NAAQS: National Ambient Air Quality Standard
(Primary)
Source: [53]
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In absence of a definitive precedent, it is difficult to assess
the specific regulations applicable to FGC disposal facilities. For
example, if the disposal site and operations are considered part of a
fossil-fuel fired steam electric plant, the emission cutoff rate for
PSD review is 100 tpy, otherwise it is 250 tpy. Further, if the disposal
facility is considered part of the fossil-fuel fired utility, and the
utility has "converted (to coal) from the use of petroleum products,
or natural gas, or both," then "for purposes of determining compliance
with the maximum allowable increases in ambient concentrations" of
particulates, the particulate emissions are not taken into account.
The question as to whether or not the FGC disposal facility and
activities are to be considered one of the 28 major emitting facilities
is critical to an understanding of which federal and/or state SIP
regulations are applicable.
In "non-attainment" areas, i.e., those areas where Federal A.mbient
Air Quality Standards have not been attained, new FGC waste disposal
activities could be subject to a review procedure including "emissions
offset" considerations. These considerations, if applied by the responsi-
ble permitting agency, would involve the implementation of equal or
greater reductions of existing emissions of the pollutant of concern as
a tradeoff to allow the emissions increment associated with the proposed
disposal activity.
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3.9 National Energy Act of 1978
In 1978 the National Energy Act (NEA) was passed by Congress and
encompassed five separate bills:
• National Energy Conservation Policy Act of 1978
• Powerplant & Industrial Free Use Act of 1978
• Public Utilities Regulatory Policy Act
• National Gas Policy Act of 1978
• Energy Tax Act of 1978
At present, detailed regulations to implement the overall frame-
work of NEA are being worked out by the Department of Energy (DOE).
The regulations would promote the use of coal, renewable energy
sources, and other alternative fules over oil and natural gas wherever
possible. While the full impact of NEA on utility and industrial
power plants needs further definition, the following appear to be
indicated:
a- All new boilers, gas turbine and combined cycle units
with a capacity larger than 10 MW will be prohibited
from using oil or natural gas unless specifically exempted
by DOE.
b. Existing facilities that are coal capable but not using
coal now may be required to switch to coal or an alternative
fuel. Financial capability to use coal or alternate fuels
will be considered by DOE. DOE will consider exempting an exist-
ing boiler without the furnace configuration and tube spacing
to burn coal. However, addition of particulate and FGD
systems may not be considered substantial modification
preventing a switch to coal. Furthermore, derating of
less than 25% by switching to coal will not be considered
substantial. These regulations will apply to single units
of 100 MMBtu/hr or more or multiple units in one site which
is aggregated by design capable of a fuel input rate of
250 MMBtu/hr or more.
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It is anticipated that NEA will encourage use of coal over the
next twenty years. Additional solid wastes and wastewater will be
generated by a switch to coal. Focus on these incremental problems
is under RCRA. As regulations under NEA and RCRA develop further,
proper meshing of these to meet the overall objectives of a national
switch to coal and environmentally sound disposal of coal-related
wastes is essential.
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4.0 ENVIRONMENTAL IMPACT CONSIDERATIONS
4.1 Introduction
This section consists of an evaluation of the results of previous
and ongoing assessments of the environmental impacts of FGC waste dis-
posal. As summarized in Table 2.5, there are some ongoing field-scale
environmental studies of FGC waste disposal. As may have been seen
throughout the text below, there are very few published results of
completed field-scale studies of this subject. Thus, much of what
appears in this report is evaluation arrived at by combining the knowledge
gained from FGC waste characterization studies (Volume 3) with the
emerging results of ongoing field-scale studies.
The focus of this evaluation is the set of potential impact issues
identified in Section 2.4 above. In addition to attempting to
prioritize this evaluation for each disposal option as described in 2.4
attempts have been made to point out, wherever possible, the degree to
which the potential importance of various issues remains unresolved in
light of the assessments to date. Further, attempts are made to
characterize the degree to which planned research may be expected to
resolve these issues. Finally, remaining unresolved issues are linked
to future research needs on the basis of the apparent magnitude and
uncertainty of their impact potential.
As an overview of all the text that follows, it is most important
to remember that there are no universally significant environmental issues
for all FGC waste disposal options at all disposal sites. The significance
of each issue for any given disposal operation tends to be a site-specific
function of three variables:
• Waste characteristics,
• Disposal practice, and
• Nature of the receiving environment.
Thus, impacts are site-specific and cannot be easily generalized over a
region. Furthermore, the existing regulatory framework, if successfully
implemented, could prevent or minimize significant adverse impacts.
Against this background, some broad generalizations on the potential
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environmental issues can be made on a regional or national basis. Poten-
tial impacts are assessed on the disposal by the major potential disposal
option of ash and FGD waste.
4.2 Land Disposal
4.2.1 Physical Stability Overview
Stability of a given disposal option can be viewed from the perspec-
tive of normal versus abnormal impacts. Normal impacts are deterministic,
that is, they can be expected to occur under usual conditions. Abnormal
events, however, are probabilistic. Such events are defined as those
which are not part of planned occurrences associated with the operation
or post-closure activities at the disposal site.
In the present case, abnormal events which may affect site/sludge
stability involve vibration, liquefaction and inundation of the site.
These events include earthquakes, presence of heavy machinery, high local
traffic volumes, flooding, and altered runoff or groundwater flow patterns.
Good design and proper operation practices can reduce the probability of
these events occurring and while it is impossible to reduce it to prac-
tically zero, it must be emphasized that with good engineering practices,
the state of the art is such that the impacts which will occur under
normal circumstances are minimal. Good engineering and operations will
be considered separately for each of the three land disposal options.
Wet Ponding
In the normal course of events, FGC wastes disposed of by ponding
will be exposed to the effects of weather: freezing, thawing, evapora-
tion, precipitation and runoff. The resulting impacts upon stability of
the waste are also determined by operational procedures in effect at the
particular site. Thus, the soundness of engineering decisions on site
operations determine the extent of impacts. The question of post-closure
use of the site will weigh heavily in engineering decisions, along with
economic considerations (which are dealt with in Section 6). This
issue becomes in reality, a public policy issue, considered under "land
use" in this section.
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Good engineering begins with an understanding of the processes work-
ing in and upon the medium at hand and then in taking advantage of them
to obtain the desired results. The ponding disposal option involves two
sets of processes—bulk physical properties of FGC sludges and grain
properties, both physical and chemical. The potential physical impact
issues for FGC wastes are settling, liquefaction and dewatering. The
grain properties of interest are bonding of the weaker and the pozzolanic
types and those resulting from grain morphology (size and shape).
While it is broadly true that crystal morphology and the sulfate/sulfite
ratio in FGC wastes do impact on physical properties, no direct relation-
ship has been demonstrated. In the wastes tested and reported in the
literature, sulfite wastes have tended to consist of platy particles of
smaller size than rounder sulfate particles. Because of these differences
in particle size and morphology, sulfite wastes have tended to be more
compressible, weaker, harder to dewater but less susceptible to liquefac-
tion failures than sulfate wastes. If sulfite particle size and shape
were altered to resemble sulfate particles, less differences in behavior
may be observed. In the field, with possible interactions and alterations
in both sulfite and sulfate particles, the situation would be much more
complex. At present, only indirect indications of behavior as a function
of sulfite/sulfate ratio have been developed.
Consideration of the abnormal event leads to cost/benefit considera-
tions. While it may be less expensive to merely build a retaining wall
to contain raw, undrained sludge, than to obtain maximum strength and
stability by dewatering (which also involves wall construction), the
latter poses much less threat to life and property if the wall fails.
In the former case, a wall failure due to earthquakes would most likely
cause an immediate liquefaction of the sludge and a flow of such veloci-
ties that would be expected to endanger life and property if they were in
the flow path. Liquefied sludges may flow as fast as water and have a
larger momentum. They are potentially as dangerous as mud flows which
have caused significant damage in the Pacific Northwest and elsewhere.
It should be stressed that with good engineering, abnormal events
will have a minimal or reduced impact, while in the absence of proper
4-3
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planning and data, the impacts could be severe. However, it may be noted
that while structural engineers can devise a safe foundation for just about
any site, the costs would probably outstrip the potential benefits of such
structures on the project involved.
In a study of six sludges including lime, dual alkali and dilute
acid wet scrubbing processes at the University of Louisville [22] it
was found that the silt-sized particles of sulfite sludges will settle to
30-35% solids while the sand-sized sulfate sludge particles will attain
60-65% solid content. When dewatered, these sludges can be reduced to
50 and 80-85% solids content, respectively. Researchers at Ontario Hydro
noted that studies by others obtained a maximum of 50% solids following
clarification of sludge in a lagoon [44] .
Research at the University of Louisville [54] has verified that both
sulfite and sulfate sludges lose strength when agitated. Sulfite sludges
will build up strength over time, but this strength will disappear upon
vibration. Sulfate sludge is nonplastic and although it is more sensi-
tive to changes in moisture content, it will also lose strength when
agitated due to liquefaction. Because liquefaction has the effect of re-
moving interstitial waters by packing the grains closer together, it is a
process which may be employed to increase the strength of a settling or
settled sludge. Induction of liquefaction in the sludge by applied
vibrations followed by pumping or draining the expelled water leaves a
denser, drier sludge mass. Until a sludge has undergone liquefaction, it
can bo classified as potentially unstable, therefore, liquefaction has
always been regarded as a process to be feared. Controlled liquefaction
can be a definite advantage.
Because it is known that at an optimum moisture content compacted
soils exhibit a maximum strength, dewatering to reach that moisture
content is a useful engineering technique. Water content can be reduced
by centrifuging, vacuum filtration and solids (normally fly ash but some-
times local soils) addition. The material may then be trucked or pumped
to the disposal site. Physical stability of the waste may be of great
importance to the possibility of reclaiming these sites. The fact that
dewatering of sulfite sludges is slow while that of sulfate sludges is
4-4
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more rapid has been clarified by ongoing research at the TVA's Shawnee
Test Facility [55] Current efforts at Shawnee have focused on the
morphology of sludge particles as affected by the type of absorbent used
in the scrubber. They verified the difficulty in dewatering sulfite
sludges but specified that lime sulfite sludge because it entraps water
between its aggregate crystals is more difficult to dewater than lime-
stone sludges. The results of dewatering as noted by Hagerty et al [54]
are a decrease in compressibility and an increase in structural strength
of the material. The addition of sand has been observed to achieve these
properties.
The grain properties of FGD sludges vary with their chemistry.
Sludges have been characterized (see Volume 3) as sulfite-rich, sulfate-
rich, or mixed, the latter containing significant fractions of sulfite and
sulfate. The characterization of sludges performed at the University of
Louisville has concluded that sulfite sludges are highly compressible,
even after compaction, have low strength and are impervious to semi-
impervious. Sulfate sludges are of low-to-medium compressibility, and
have similar permeability characteristics when compacted. Sulfate sludges
may collapse unpredictably due to liquefaction when saturated. In analyzing
research and studies performed by others, SCS Engineers [28] have reported
that light compaction of dewatered sludge will result only in a small improve-
ment of structural strength. Another researcher [56] has found, however, that
the dewatering and compaction, especially of sulfite sludges has reduced the
4-5
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compressibility significantly. A mixed sulfite/sulfate/sludge with 35%
water content was subject to liquefaction after 30 days in a 30-cm
layer [22]. Studies of dewatered sludge behavior under loading have pro-
duced varying results. SCS Engineers [28] have reported that other re-
searchers have found that settlement is unavoidable even after heavy com-
paction, although it may be less than the settlement of most common soils
under the same circumstances. Deposits of unstabilized sulfite sludge
filter cake might be highly compressible, even for light structures [22],
The same authors have reported that the compressibility of sulfite sludge is
within acceptable engineering limits for light to medium weight struc-
tures. Investigations of uncompacted sludge have determined that under
low confining pressures, sludges may lose their shear strength under
dynamic loading. Sulfate sludges not only consolidate less but undergo
consolidation much quicker than sulfite sludges. For example, an uncom-
pacted sulfite sludge has been observed to consolidate by 10% of its
original height of 20 feet in two months, while an identical sulfate sludge
layer completed its lesser consolidation in two weeks.
Physical blinding has been observed between FGC sludge and soil
layers in contact which has implications for leaching at some disposal
sites. These sludges have insignificant effective cohesion, however,
which places an upper bound on the load they can withstand. Field values
have been observed to be lower for all physical characteristics including
permeability, maximum dry density and compressive strength. Pozzolanic
activity may produce a partly cemented material which is brittle and
friable, rather than cohesive [57]. In an ongoing study of waste products
from certain western coals (lignite) the fly ash was found to be highly
alkaline and has been successfully substituted for lime/limestone in
scrubber systems. This system (used at Milton Young Station in North
Dakota) produces an alkaline gypsum sludge in which pozzolanic activity
has been observed. The physical properties of this sludge are within
the ranges for most lime/limestone sludges [58]. The moisture content
of this sludge, which is approximately 30%, makes it a good candidate for
ponding.
4-6
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Field behavior of dewatered sludges has been studied by three research
groups: University of Louisville [22,56], Sikes and Kolbeck [57], and
Aerospace, Inc. [37]. The former have observed that freezing of sludges
may cause dewatering or layering. The Aerospace study [37] reported that
dumped piles of partially saturated gypsum sludge slumped when wetted by
rainfall. In all likelihood, this precipitation destroyed capillary suction.
Properly compacted gypsum wastes would not be subject to loss of stability
upon saturation. Such deposits will form £i impervious surface layer
(due to pozzolanic action) which has been observed to crack during freeze/
thaw conditions. This presents the possibility of new opportunities for
leachate formation and may imply that gypsum sludge disposal sites be
maintained regularly as a function of weather conditions. The latter
group performed a study comparing field and lab tests of two types of fly-
ash sludge deposits. The inplace dry density of the two sludges were 85%
and 99% of the laboratory value; inplace moisture contents were 69% and 58%
of lab optima. The field compactions achieved were 85% and 99% of the
theoretical optima. The waste which performed best in the field had a
finer range of grain sizes, a lower optimum moisture content and higher
wet and dry densities and was chemically less complex.
Many of the major physical properties of FGC wastes have been
investigated to some degree. A particular lack of information exists
for the compressibility of dewatered fly ash wastes. Further research is
needed in correlation of field performance with laboratory tests. The
conditions which will induce liquefaction require greater definition.
4.-2.2 Public Policy and Land Use
The focus of this review centers around three aspects of FGC waste
disposal by impoundment:
• Site location,
• Post-closure land use, and
• Impact potential of disposal on adjacent lands.
It should be noted that for public policy considerations, in particular,
issues identification is somewhat speculative based on existing (but
changing) regulatory framework and projected incremental land require-
ments due to projected increases in the use of flue gas cleaning systems
well in the future.
4-7
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Site Location
The site location issue may be viewed from two perspectives: (1)
space requirements for disposal of the cumulative, increasing generation
of FGC wastes and (2) the location of a specific FGC disposal site.
A typical 1000-MW plant will require 160 to 280 hectares (400 to 700
acres) for disposal of ash and FGD sludges over a lifetime of 30 years
depending upon the type of coal to be used and the region in which it is
located. The 160 to 280 hectares (400 to 700 acres) include only the ex-
cavated area (dry disposal or ponding); the actual disposal area required
may be much larger since land would be required for access roads, truck
parking and unloading areas, and buffer zones to screen off the disposal
area. It is anticipated that in the future public pressures will result
in greater attention to buffer zones in populated or recreational areas
to minimize the adverse aesthetic impacts of disposal areas.
The area of land required for disposal of FGC wastes from a typical
100-MW industrial boiler may be more than 10% of that required for a
1000-MW utility boiler discussed above if the FGD svstems are identical
nonrecovery units. The height of a managed fill for an industrial boiler
is likely to be less and, hence, proportionately more area would be
required (although the volume of wastes for a 100-MW boiler will be 10%
of that for a 1000-MW boiler. Cumulative vastes generated by an industrial
boiler during its lifetime will require from 16 to 26 hectares (40 to 65
acres) for the disposal area along with perhaps an additional 20 hectares
(50 acres) required for unloading areas, vehicular movement and buffer
zones. It should be emphasized that many industrial units may employ
sodium based FGD processes and produce liquid wastes. In many cases, the
latter may be integrated into the water and waste management plans of the
whole industrial plant (rather than treated or disposed of as FGC wastes.
Based on the data concerning the cumulative generation of coal ash
and FGD wastes presented in Section 2, the same order of magnitude esti-
mates on land requirements for disposal are summarized in Table 4.1.
These are for illustrative purposes only and not intended as estimates on
land use.
It appears that the following conclusions on land use are valid:
4-8
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Table 4.1
Cumulative Land Requirements
for Disposal of FGC Wastes
Basis: 1. Pre National Energy Act of 1978 estimates on
coal utilization.
2. All FGC wastes disposed on land as moist
material in lifts of 10 meters (32.8 feet).
3. Only excavated disposal area mentioned.
Actual land required including buffer zones
and access roads may be 2 to 3 times the
listed amount.
No.
1.
2.
3.
Coal Ash Alone
FGD Waste Alone
Total FGC Wastes
By 1985
Sq km (Acres)
39.6 (9750)
16.2 (4000)
55.8 (13,750)
By 2000
Sq km (Acres)
130 (32,100)
65 (16,050)
195 (48,150)
Source: Arthur D. Little, Inc.
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• From a regional or state land use perspective, these land require-
ments are not large.
• Federal Regions 5, A, 6, and 3 (in that order) are projected to
require maximum total land and maximum incremental land. While
individual disposals would result in a loss of land for other
purposes, the impact when considered on a regional or national
scale is not very large.
• Much of the land area required for disposal between 1985 and 2000
would result from the establishment of new utility plants and in-
dustrial boilers. It is anticipated that these "energy centers"
will require a larger land area than previous facilities and hence
be sited in relatively rural areas. Political and economic fac-
tors are expected to increase land use planning for such uses and
place additional regulatory constraints on utilities and industry.
Potentially, demand could arise to combine utility plant and dis-
posal area into one site, reducing requirements for off-site dis-
posal.
While land requirements for FGC waste disposal are not large on the
national or regional scale, at the local level land use could become an
issue on a site-specific basis. FGC waste disposal areas are usually
zoned for industrial use. This land use may not be compatible with other
uses such as residential, commercial, and recreational.
One of the largest operating FGC waste systems utilizes a 560-hectare
(1400-acre) impoundment for the disposal of treated sludges from a two
unit 1650-MW power plant. While a third unit is under construction, the
impoundment was designed for 30-year use, assuming a filled depth of 400
feet of waste [59]. This example may be exceptional because of the large
operation size combined with impoundment disposal planned for one site.
Future location problems for such large impoundments could exist, although
they are expected to be location specific. A "hazardous" or "non-hazardous"
designation for FGC wastes would not alter land requirements for disposal
but could potentially increase location-specific problems with siting.
The aesthetics of a disposal operation can have an effect on site
location due to local public reaction. Such problems, where they occur
are not expected to be significantly different from location problems for
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other types of waste disposal areas. If anything, they may be less because
of the uniform appearance and relative absence of odor with FGC wastes.
Post-Closure Land Use of Impoundments
Considering the amounts of land area that could be required for FGC
waste disposal on a site-specific basis, the issue of post-closure land
use is an important one. Constraints on post-closure land use are related
to the site, type of waste, method of disposal and climate. Many of the
specific issues in question concern waste characterization and its relation-
ship to long-term disposal physical stability and chemical stability.
Research in these areas is discussed in greater detail under each of those
headings, with the issues addressed here only as they relate to disposal
site post-closure land uses.
For wet impoundments that are drained following disposal operations,
the major issues are those discussed below for dry impoundments. Where
water cover is intended to be left over the disposal impoundment, several
additional issues exist:
• The water quality of the supernatant water,
• The impact potential of the supernatant water on terrestrial and
aquatic species, and
• The impact potential of released water on downstream users.
4.2.3 Wet Ponding
Some of the generic environmental issues pertaining to any method of
FGC waste disposal on land were discussed above. In this subsection, the
focus will be on wet ponding.
Physical Stability Issues
The issues concern liquefaction and other abnormal events. There
are several aspects to this issue: :
• Development of appropriate engineering basis for the particular
waste involved,
• Design safety factors to be adequate for the specific site taking
into account the potential impact of abnormal events, and
• Adequate monitoring of the site including embankments, dikes or
dams.
Physical stability impact issues can in principle be minimized with
proper engineering design and operation.
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Water Quality Considerations
Many, if not all, FGC waste disposal water-related impacts arise
from the migration of leachate and/or runoff. Consequently, labora-
tory tests of leaching characteristics of FGC wastes are of general
relevance to all land-based disposal options. Impoundment of FGC
wastes with water cover can present a significant potential for
related impacts because the head of water promotes percolation of
water through the wastes and would (theoretically) eventually cause
the water table to rise to pond level, maintaining an intimate contact
between waste and groundwater. This process can be avoided by:
• Wet stabilization process, wherein the settled wastes undergo
pozzolanic reaction to produce a layer of very low permeability.
The Dravo wet process is an example.
• The use of an impermeable liner under the pond to contain the
leachate. Liners are not fully proven at present; research
efforts now underway should produce useful data on their applic-
ability in the immediate future. For practical purposes, contain-
ment may be considered effective if the leakage is adequately
delayed and/or maintained at a low rate. Thus, the effectiveness
of liners and their rates of deterioration in contact with FGC
wastes in various environmental settings is an important considera-
tion in assessment of environmental impact of FGC waste disposal
in impoundments with a maintained water cover.
Of primary importance to water impacts is the rate of pollutant mass
release (mass/time) to the surrounding ambient water via leachate. This
quantity may be estimated by the product of leachate quality (mass/pore
water volume) and waste permeability/length/time by disposal area. The
actual pollutant release rate cannot exceed this amount, although in dry
seasons the actual rate of leachate generation may be far less than in-
dicated by the product of permeability and area. Setting aside the very
important site-specific considerations such as leaching solution charac-
teristics (water quantity, quality, and flow pattern), surrounding soil
permeability, and disposal site area, an intrinsic waste property of
particular significance to water contamination is pollutant flux (mass/
4-12
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area/time) which is the product of each pollutant's equilibrium leachate
concentration and the permeability of the waste. This waste property
could be established by standardized leaching and permeability tests.
At this time, the development of standard leaching tests continues. No
procedure has been generally recognized, nor have general interpretive
rules been established to relate these intrinsic leaching properties of
wastes to field environments. Nonetheless, comparisons of intrinsic
pollutant flux for various FGC wastes have been reported indicating that
the intrinsic flux from chemically stabilized FGC wastes would be one or
two orders of magnitude less than from unstabilized FGC wastes. However,
precise estimates on the total impact of chemical stabilization should
include:
• Impact of surface runoff, and
• Impact of permeation on a site-specific basis.
A number of R&D programs on leachates have produced data on leaching
behavior as described in detail in Volume 3.
Once a waste is placed in any type of land disposal site, its initial
contact with water would tend to flush out interstitial waste liquors:
initial leachate quality could be similar to that of the occluded liquor.
The initial volume of water within the waste is equal to the pore volume
(porosity times the total volume of waste). After several pore volumes
of water have passed through the waste deposit (PVD = pore volume displace-
ments), most of the occluded water will have been flushed and the leachate
concentration of major ions is expected to approach steady state corres-
ponding to the solubility of the major constituents in the solid phases
of the waste. These solubilities are often pH and temperature dependent,
and thus the long term leachate quality will also depend on pH and tem-
perature. In theorv, trace metals also approach an equilibrium value.
However, Rossoff, et al.[37] investigated nine trace metals and could find
no evidence that solubilities of metallic compounds (oxides, hydroxides)
controlled the equilibrium concentration.
Leo and Rossoff [60] have investigated the first flush effect for five
specific disposal scenarios and find that the first flush of occluded
waste liquors may affect leachate quality for as little as ten years
4-13
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(for ponding) or as long as 1300 years for a managed landfill of stabi-
lized sludge. Water quality impacts of ponding are consequently likely
to be controlled by the long term equilibrium mass release rate of pollu-
tants and the nature of receiving waters on a site-specific basis. The
long term mass release rate of pollutants is controlled by equilibrium
leachate quality and the rate of leachate and runoff generation. The
rates of leachate and runoff generation are affected by many variables
including meteorology, hydrology, site management, and waste permeability.
Laboratory Tests of FGC Waste Leachates
Laboratory tests of leachate quality are indicative of relative
differences between wastes but are less than fully relevant to assessment
of disposal impacts because certain environmental conditions cannot be
reproduced in the lab. Further discussion of FGC waste leachate quality
may be found in Volume 3.
It was reported [37,60] that equilibrium (40-50 PVD's) leachate con-
centrations were not significantly dependent on pH. TDS and sulfate
levels tended to similar values of approximately 2000 ppm and 1200 ppm,
respectively, regardless of waste type. It was indicated that these con-
centrations are probably controlled by the solubility of the CaSO, component
of the sludge. The only exception was a sulfite-rich sludge whose equilib-
rium TDS and S0~ concentrations were much lower than the others, indicat-
ing that CaSO, solubility was not dominant for this sludge. These leaching
tests were conducted under aerobic conditions, while field conditions for
leaching of sulfite-rich sludge are more likely to be anaerobic (although
oxidation of the sulfite also probably occurs in the field). Thus, it is
reasonable to expect that under field conditions, sulfite-rich FGC wastes
even those containing greater than 5% CaSO,, will yield leachate whose
equilibrium TDS and SO, concentrations will be significantly less than in-
dicated by CaSO, solubility. However, the leachate concentrations of
major species in mixed and sulfate-rich sludges are expected to be con-
trolled by CaSO, solubility.
Sulfite-rich sludges in anaerobic conditions are expected to generate
leachate having a high chemical oxygen demand (COD) present as total oxi-
dizable sulfur (TOS). Without relevant field testing and experience, it
4-14
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is difficult to assess the importance of this TOS content to water quality.
Groundwater in the saturated (water table) zone is deoxygenated by micro-
bial activity. When drawn to the surface in wells, it is well aerated
during the pumping or sampling process. Only where surface water bodies
receive leachate or runoff-related flows is the oxygen demand expected to
pose any potential environmental problem, and the extent of this problem
would be extremely site-specific.
The results of leaching tests conducted to date tend to indicate that
the degree of oxidation of the waste can lead to significant differences
in leachate quality, with sulfite-rich sludges expected to yield leachate
with lower TDS and SO^ concentrations, but with a greater COD (Lunt, et al.)
As reported in Volume 3, there is some evidence to suggest that
sludges containing fly ash yield leachate containing significantly higher
levels of some trace metals (e.g., arsenic) than ash-free sludge (Radian,
Rossoff ,et al. , Final Report 68-02-1010). However, Leo and Rossoff [61] con-
clude that the differences in leachate quality are not dramatic and that
flyash removal upstream of the scrubber will not significantly improve
the trace element leachate quality in relation to the pollutant hazard.
Unfortunately, so few tests have been conducted with ash-free FGC wastes
that this question is not clearly resolved.
Equilibrium leachate concentrations of major constituents show no
dependence on scrubber absorbent (lime, limestone, double alkali) but
trace element leachate quality is observed to depend on absorbent and
type of coal [62].
The quality of leachate depends not only on the type of waste, but
also on the nature of the leaching solution. Leaching may occur in
several ways, including surface leaching of impermeable materials, with
subsequent runoff which may eventually enter surface or groundwater; by
rainwater percolating downward through permeable wastes; or by groundwater
flowing horizontally through the waste mass. Rainwater, the leaching
solution in the first case, will be well aerated, and of variable pH (4-7)
in the U.S. (more acidic in the NE, more basic in the west and south).
Percolating rainwater and groundwater quality will change as it interacts
with the waste, and is likely to be reduced in dissolved oxygen by mixed
4-15
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and sulfite-rich sludges. Most FGC wastes are neutral or alkaline and
thus the leaching solution, even if initially acidic, will tend to become
more basic.
Preliminary results from column leaching tests at WES [62] indicate
no significant variations of leachate quality with pH of leaching solution.
These results are corraborated by the study of Duvel, Rappand Atwood [63]
comparing leachate: quality for two different leaching solutions: dis-
tilled water and a synthetic solution analogous to acid mine drainage.
Certain trace metals were leached only slightly more effectively at low
pH, but a precipitate of iron sulfide was formed. Leo and Rossoff [61]
found that the trace metals Pb and Zn are leached more readily by acid
leachate while only Pb, of the trace metals analyzed, showed a' significant
difference in aerobic/anaerobic comparisons (higher for anaerobic). Data
on leaching from stabilized FGC wastes is not fully conclusive data although
reduction in trace elements is reported [60].
Besides leachate quality, FGC waste permeability is an important
disposal parameter amenable to laboratory testing. However, as discussed
in Volume 3, laboratory tests of permeability may not be relevant to
permeability in the field. Sample disturbance; passage of water around,
rather than through, the sample; and stratification of field deposits are
common causes of unrepresentative laboratory results, while weathering,
particularly freeze/thaw cycles, are expected to change in situ permeabili-
ties over time.
Unstabilized sludges consistently exhibit permeabilities of 10 to
-4
10 cm/sec while stabilized sludges show permeabilities one to two orders
of magnitude lower. Sulfite-rich FGC wastes are generally less permeable
than sulfate-rich ones because of their "flat" crystalline morphology.
Addition of fly ash, fly ash and lime, fly ash and cement, or the proprietary
additive Calcilox will reduce permeabilities by about an order of magni-
tude although the reported effectiveness of treatment in permeability
reduction is quite variable [37,60,64].
To close this discussion of laboratory tests pertinent to wet impound-
ments and all other land-based disposal options, soil attenuation of
leachate constituents must be considered. Because of the great variety
4-16
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of soils and wastes, this again will be a highly, site-specific considera-
tion, but laboratory results should provide some guidance on the question
of whether the soils surrounding a disposal site will be capable of retain-
ing potentially problematic ions associated with leachate. Two studies
that may offer guidance in this regard are:
• Radian study for EPRI [40]. This study entailed not only
laboratory measurements of leachate/soil interactions, but also
the development of an analytical model which permits scale-up of
their laboratory results to facilitate field-scale estimates of
soil retention. Anionic forms were not retained by the bulk of
solids. Radian tests involved synthetic mixtures of soils (with-
out organics) and field samples. Since trace element levels were
low, Radian increased concentration to study effects.
• U.S. Army Materiel Command, Dugway Proving Ground is also perform-
ing soil attenuation studies, the results of which had not been
published as of early 1979. However, preliminary results are
broadly consistent with the Radian findings.
Field-Scale Research
Pilot scale tests of pond disposal of FGC wastes have been undertaken
at TVA's Shawnee facility and by Louisville Gas & Electric Co. (Paddy's
Run) while full scale pond disposal is being monitored for potential well
contamination at the Bruce Mansfield disposal reservoir by Pennsylvania
Power & Light. Preliminary results at Shawnee and Bruce Mansfield indi-
cate no significant contamination of groundwater to date [60,65]. How-
ever, these results may not be significant because the disposal ponds
have been in operation for less than five years and there is no reason to
expect that pollutants would have migrated from the site via groundwater
•
in such a short time. This points out a fundamental problem in ground-
water protection: field verification and experience is gained very slowly.
Laboratory analyses of supernatant, leachate, and permeability of samples
from field disposal sites provide valuable information relevant to actual
disposal conditions:
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• It was reported that compaction at the bottom of these relatively
shallow ponds can reduce the waste permeability by a factor of
2 to 5. Aerospace [61] concluded that compaction at the bottom
of a 12 meter deep pile of FGC waste will decrease permeability
by one order of magnitude.
• Aerospace studies [50,61] note that at Shawnee,after allowing for
weather, leachate concentration of the major solubles dropped to
one-half to one-third of input liquor.
Aerospace Corporation, at TVA's Shawnee facility, is investigating
an underdrained pond system in which leachate is collected for treatment
or reuse. One potential advantage of this system for water-related impacts
is the reduction in head which accompanies drainage, thus reducing per-
colation into the region below the site. In areas with appreciable rain-
fall, underdraining requires [39] dividing the disposal area into several
sections (over the life of the plant) using one section at a time from
the surrounding water bodies. Reduction in the amount of leachate
generated may be accomplished for ponding scenarios by diverting the entry
of surface runoff from adjacent areas. The high water content and fluidity
of impounded FGC wastes make site management to promote runoff and eliminate
standing water difficult or impossible to achieve.
Waterways Experiment Station of the U.S. Army Corps of Engineers has
been conducting field studies on the effects of FGC waste disposal on
adjacent soils and grounwaters. While final results are likely in 1979
it is noted that earlier WES reports on three FGC waste disposal sites
[66] have been reported. These sites had been utilized for FGC waste
disposal for five to nine years. Well samples were analyzed for major
soluble components of sludge and several trace metals. Soils were ex-
tracted and analyzed to determine if adsorption on soils was occurring
that might attenuate leachate migration. Distinct leachate plumes were
not resolved and migration patterns were reported to be complex. However
careful statistical tests reportedly revealed that groundwater at all
three sites exhibited increased contaminant concentrations as a result of
the disposal operation and that there was little or no evidence of attenua-
tion of some pollutants by the soil [66].
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Aerospace [61] has performed an analysis of the potential for ground-
water pollution in terms of the flux of IDS to subsoil over a 150 year
period. They considered five disposal scenarios including impoundment of
stabilized and unstabilized FGC wastes, both with and without diversion of
runoff, and managed landfill of stabilized waste. The analysis incorpor-
ates certain site-specific aspects by specifying that the natural ground-
water recharge rate is 10 in/year and the depth of waste is 30 feet.
Their analysis is not generally applicable to all disposal environments.
According to that analysis, diversion of runoff from an impoundment such
that it is not covered by water, is more effective than chemical stabiliza-
tion in reducing the potential for prevention of groundwater contamination.
A well managed landfill of stabilized sludge, including grading to promote
runoff, presents the lowest potential for groundwater contamination
according to their report. However, the promotion of runoff is not always
consistent with the protection of surface water quality on a site-specific
basis.
Site management over indefinite periods of time may thus be a major
requirement for pond disposal due to the potential for impact without
strict management. However, Aerospace [61] also concluded that the under-
drain system with collection, and treatment or reuse of leachate would re-
sult in improved physical stability such that long term site management is
a much less serious problem. Furthermore, liners would not be required to
protect groundwater. The ideas expressed in that report [61] are being
field tested at the pilot scale at TVA's Shawnee plant at this time.
Other Potential Impact Considerations
In addition to the land use and water quality issues discussed above
for wet impoundments of FGC waste, two other types of potential impact
issues were identified in Section 2. These are air quality related and
biological issues. The former are considered of little or no environmental
significance for FGC waste disposal in wet impoundments, and have not been
the subject of empirical environmental assessment studies. Biological issues
such as revegetation requirements, could be of significance, but also have
not been studied empirically for wet FGC waste impoundments. This point is
discussed in the summary of data gaps and research needs (Section 4).
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4.2.4 Dry Disposal
Four types of FGC waste may be disposed of in dry form:
• First, bottom and fly ash which have been collected pneumatically
often these two material flows are combined for disposal but this
is not always the case.
• The second group includes gypsum sludges from conventional FGD
systems on low sulfur coal or forced oxidation FGD systems.
• The third group is the stabilized sludges. Both sulfite and sul-
fate sludges are stabilized by chemical treatment and although
dewatering is often a preliminary step to stabilization, it is not
a stabilization process by itself. Stabilized sludges are often
placed in the disposal site while still containing as much as 30%
moisture. This water is, however, chemically bound and plays an
important role in the curing process which renders stabilized
wastes into much harder aggregates.
• The last dry wastes are those generated by dry aorbent desulfuri-
zation techniques. These techniques are currently receiving a
high level of attention and commercial systems should be operative
in the early 1980's. Unfortunately there exists a large data gap
about the materials produced by these processes and this is a
very important area to be focused upon as a result.
Physical Stability Issues
The generalized discussion in Section 4.2 also applies here. In
addition, because so many of the inherent problems of FGC waste have
been ameliorated by stabilization or disposal without water, the physical
stability impacts associated with this option are virtually negligible
when good disposal design and practice are followed. Normal field con-
ditions do have the potential to interfere with the proper resolution
of stabilization processes and to inundate the dry wastes. Thus, the
engineering focus shifts from construction (as it was for ponding) to
operations, to ensure the attainment of the increased stability of dry
and treated wastes. Due to the high strength of many of these wastes,
the final use potential of the site is relatively broad, and it can
become an economic incentive that field conditions do not interfere with
material strength.
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From this perspective, abnormal events are cast differently as well.
They are any event which, within the scope of available planning and
engineering technique, the disposal site manager cannot accommodate. For
instance, during a tremendous storm, the disposal site is flooded and the
available pumps cannot drain it fast enough to prevent seepage into and possibly
saturation of the top layer(s) of the landfill. Other such occurrences
include shortages of crucial supplies and other unusual weather problems.
Poor engineering would be defined in this case then by a lack of
attention paid to field operating conditions and procedures. Such events
as uncontrolled rainwater runoff entering the freshly placed wastes,
wastes placed before curing or left in a position where curing is inhibited,
development of thick lifts and improper compaction may all contribute to
a reduction of the physical stability of the completed disposal area.
The Waterways Experiment Station [67] reported on testing of five
sludges of varying sulfur content, origin and scrubber type. Fixation
generally resulted in a consolidated material of increased density, de-
creased porosity and decreased permeability with some degree of structural
strength. These results held true for processes producing a concrete-like
material. Soil-like sludges produced from stabilization processes, were
more porous than concrete-like sludges and raw sludges exhibiting increased
permeability and decreased strength. Material properties are highly
dependent on the stabilization process and were consistent for each process.
Fixation was observed to have a greater effect on stabilizing double alkali
sludges than limestone sludges.
The work at WES was reported on more recently by Bartos and Palermo
[68]. The research indicated that fixation (stabilization) generally re-
duces sludge plasticity although the plasticity level of sludges is already
quite low. The compressive strength is highly dependent on the process
and sludge type; the strengths are typically approximate to those of
soil-cement mixtures or low-strength concrete. Several of the processes
produced materials comparable to low-strength concrete; one material, a
stabilized western coal/limestone sludge had a compressive strength in
2
excess of 280 kg/cm . The bearing capacity of soil-like stabilized sludges
is comparable to low strength concrete and soil-cement type sludges should
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be adequate for most landfill applications. WES also found that durability
is related to the stabilization process. Aerospace assessed ponding and
landfill concepts for FGD wastes [60] and concluded that some control for
runoff, seepage and direct discharge of water may be required.
Investigations by Thacker [56] involved the addition of fly ash to
sulfite sludges. It was found that compression under load was reduced
but not enough to allow the sludge to meet engineering criteria for lead
bearing foundations. No time-dependent bonds were developed in fly ash-
sulfite sludge. The addition of fly ash to the sulfite sludge did not
produce an increase in the shear strength but did lower the strain causing
shear failure. The compression of this sludge-flv ash mixture was within
the range encountered in natural soils.
At the Columbus and Southern Ohio Electric Conesville Station, a
thiosorbic lime FGD system produces a 30% solid mixed sludge. This sludge
is stabilized by an IUCS process. This sludge was compacted to ig/cc
o
(65 Ibs/ft ) dry density in 60-cm (24-inch) layers. Tests found that the
2 2
material can bear more than 5kg/cm (5 tons/ft ). The structural capabil-
ity of this material may be better than for most fills. Investigators at
Aerospace [60] have found that chemically stabilized sludges may attain
a high load bearing strength.
The physical stability of chemically treated FGD sludges can be
evaluated by knowledge of the material's compressibility, shear strength,
density, bearing capacity, consolidation characteristics and durability.
While each stabilized sludge will behave uniquely, the general charac-
teristics of soil-like and concrete-like sludges outlined above present a
comprehensive data base. Further research is needed to verify these re-
sults and increase the amount of available information. An important
issue which has not been investigated is the compressibility, consolida-
tion and bearing capacity of FGC sludges in combination with other wastes
in a sanitary landfill. The chemical reactions which might occur by the
placement of such diverse wastes in contact could possibly have an effect
on morphological and thus physical characteristics of the fill as a whole.
While some field investigations on FGD sludge durability have been
performed, no attempt has been made to correlate and explain the varia-
tion between in-field physical test results for stability and laboratory
analysis. 4-22
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Physical blinding has been observed between FGC waste and soil layers
in contact [22] which has implications for leaching at such disposal sites.
Small particles of sludge fill the interstices between larger particles of
natural soil, thus, lowering the permeability of the natural soil. These
sludges reportedly have insignificant effective cohesion, which places an
upper bound on the load they can withstand. Field values have been observed
to be lower for several physical characteristics including permeability,
maximum dry density and compressive strength.
Land Reclamation Issues
The major issues surrounding land reclamation of dry impoundments
include:
• Revegetation potential,
• Toxicity potential of sludge substrate, and
• Suitability of disposal area for post-closure uses based
on physical stability in varying climate regions.
When the land disposal options are selected, consideration of
restoration must address the terrestial plant cover. In the arid and semi-
arid portions of this country, plants are very sensitive and require care
in selection and replanting; for instance sage brush pods must be processed
through the digestive system of an animal or synthetically stressed to
insure proper seed germination. Also, often the overburden topsoil is very
thin (3-6 inches) and must be carefully segregated for future use in
restoring the disposal site.
Revegetation of ponded areas can be used to prevent erosion of dried
•
fine material and as a step toward reclamation of the area to other uses.
TVA has initiated field testing of dewatered sludge pond revegetation.
Legumes, grasses and forest tree species are being examined. Survival
and growth rates are not presently available but preliminary results
have indicated that: (1) the sulfite and boron content of certain
limestone sludges are potentially toxic to some plant species (boron
uptake has been observed); and (2) soil amendment with plant nutrients
such as nitrogen and phosphorus may be required to sustain growth.
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The physical stability of the disposal site would dictate the range
of post-closure uses. As indicated by laboratory test results, treatment
of sludge material significantly alters the bearing strength of disposed
FGC waste material. Untreated FGC wastes, especially those high in
sulfites, can tend to liquefy. This characteristic has caused some to
report that the use of even lightweight machinery could be difficult.
However, experience with test ponds by TVA has indicated that once ponds
are sufficiently dewatered, lightweight equipment can be utilized [69].
Based on laboratory work, Klym and Dodd [70] report that for
impoundments of untreated FGC waste, two to three feet of fill would
be needed over the waste to provide a working surface, and at least an
additional five feet of fill for surcharging the sludge to obtain a
stable landfill [70].
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However, reasonable post-closure land use decisions are difficult
without better definition of the behavior of large amounts of FGC waste
material through field verification.
Restrictions on post-closure land use based on physical stability
need to be examined. While it appears that re-use of impounded stabilized
FGC materials may be restricted to parks or other uses where low loadings
or tolerance of settlement can be accomplished [71,72], greater under-
standing of loading capacity of large volumes (depths) of stabilized FGC
materials would be useful. In other words, correlations between FGC
materials and other substrates (e.g., natural soils) would provide a better
understanding of land reuse possibilities.
The effects of climatic conditions on dry disposal sites also requires
field verification. Long term measurements of chemical or morphological
changes as a result of freeze/thaw action have not been made [72], Simi-
larly, field testing of the effects of inundation and drying on large
volumes of FGC wastes (as in an impoundment) need to be made. While fill
or cover of an impoundment with relatively impervious material has been
recommended to minimize contaminant leaching, the potential effects of this
approach on physical stability may need to be identified. In summary,
correlations between lab tests and field behavior of soils have been de-
developed, but such correlations do not presently exist for FGC wastes
[71, 72].
Revegetation potential and especially the potential for contamina-
tion of food-chain vegetation has yet to be investigated for the broad
range of FGC wastes. The amount of soil amendment and/or depth of fill
required to establish vegetation, the potential for upward migration of
major species and trace contaminants such as heavy metals and the incor-
poration of these contaminants by a wide variety of species also have yet
to be investigated. Soil-waste interactions in terms of water and nutrient
holding capacity could be far better understood, as well as the effects of
deep root systems on cracking and permeability of large-volume FGC waste
impoundments.
Limitations on post-closure uses of landfilled FGC wastes of varying
characterizations have not been thoroughly investigated. In addition to
physical stability issues described above, safe fill heights have yet to
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be established. While design charts have been published for maximum safe
fill heights for certain soil types, such information has not been estab-
lished for various FGC wastes[71]. Triaxial compression tests on consoli-
dated samples, with measurement of pore water pressures would help to
establish maximum safe fill height in relation to slope angle and waste
shearing behavior[71]. While disposal site engineering and/or post-
closure practices can likely be tailored to the bearing capacity of the
wastes, the basis for these practices has yet to be fully established.
Water Quality Issues
Permeation and runoff of leachate from dry disposal is a significant
issue. Discussions on permeability, leachate quality and intrinsic pollu-
tant flux found above are also relevant to dry disposal. The dry disposal
methods may have a lesser level of water quality impacts for several
reasons:
• Several site management practices are feasible for dry disposal
operations which are infeasible or more difficult for wet impound-
ments. These include grading to promote runoff, and isolation of
the wastes with respect to the surrounding waters[36,61,65].
• The relative absence of free moisture initially would be expected
to alter and probably reduce any first flush effect associated
with the leaching of occluded waste liquor.
• Untreated sulfite-rich FGC wastes which pose a potential water
related impact associated with the high COD of leachate generated
under anaerobic conditions, cannot easily be dewatered to the
point where dry handling is feasible. This makes the disposal
option less likely for a waste type of high impact potential.
Of these considerations, the first is probably the most significant
and has been discussed by Leo and Rossoff [61]. They concluded that grading
to promote runoff and eliminate standing water, coupled with diversion of
runoff from adjacent areas, would reduce contaminant loading from FGC
waste to groundwater by an order of magnitude—compared to the reported
benefits of chemical treatment.
Some field-scale evaluations of water quality impacts are in progress
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as presented (Table 2.14). To date, no substantive results
pertaining to water-related impacts associated with dry disposal methods
are available from these disposal studies. As was noted above, for pond
disposal, it is unusual for field evaluation of groundwater impacts to
provide substantive results within periods of less than five years be-
cause contaminant migration through wastes and soils tends to occur very
slowly.
Other Considerations
With very few exceptions, the potential air quality related and
biological impact issues associated with dry FGC waste disposal have re-
ceived very little attention in the form of empirical research.
FGC waste landfills or dry impoundments, if designed to remain un-
covered by other overburden upon closure, could be sources of some fugi-
tive particulate emissions after disposal operations ceased. (During and
shortly after disposal, even the driest FGC wastes have more than the
5 to 10% moisture content required to resist wind erosion.) This issue
does not appear to be addressed by previous, ongoing or planned research,
but its potential overall significance does not appear to be large relative
to other issues.
Mechanisms of potential biological impact are discussed in Section
2 above. Of these that apply to dry disposal, none appear to have
been studied in the past and one is currently under study. The present
study concerns the revegetation potential of dewatered FGC waste ponds.
It is being performed by TVA, the Aerospace Corporation, and others as
part of the EPA-sponsored Shawnee Field Evaluation program. Only early
results of this work are available. These are discussed in Section
4.2.2.2 above.
4.2.5 Mine Disposal
FGC waste disposal at mine sites can potentially take three forms:
subterranean placement, burial in enclosed lifts and bulldozing into
embankments. Each method is unique and engineering criteria vary
accordingly.
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Physical Stability Issues
Underground disposal requires a pumpable material for methods
designed to date. Fly ash, bottom ash and raw FGC wastes may all be
disposed in this fashion. Because the disposal scenario involves waste
containment by bulkheads, the strength and anchorage of the bulkheads
is an important engineering issue. Analysis of geologic strata as they
affect secure bulkhead placement and leakage to aquifers plays a part
in good engineering. Under normal conditions, the security of the waste
is not threatened. If it is entirely contained, with drainage and treat-
ment of drawn-off wastewaters performed, impacts of stability and also
groundwater may be of little importance. Final land use is practically
an unrelated matter and may conflict only with the pump station above
ground. Abnormal events are those which would interrupt the geological
integrity of the site. This presents more problems for groundwater con-
tamination than in causing stability problems. While an earthquake shock
may fracture an FGC waste containment structure and the now liquefied
waste would flow through the mine, unless the mine were active, no loss
of life and property would ensue. A possible result of such a failure
is surface subsidence caused by the sudden release of strains built up
over time around the sludge-filled cavities. This possibility is
regarded as highly unlikely by some researchers [117].
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General considerations discussed in Section 4.2.2.1 also apply here.
In addition, the stability issues of surface mine pit disposal are the same
as those for the dry disposal. Additional information will be required to
correlate results of field studies with the results of lab and model tests.
An unresolved issue regards the effect on stability of acid mine drainage
in contact with FGC wastes. To date, this has been investigated only
with respect to leachate formation. Also along this line is the stability
of various combinations of fill materials in the spoil pit: FGC sludge,
mine tailings, overburden, etc.,which has not been studied in the lab or
in the field. Because so much of the behavior of FGC waste can be attri-
buted to the nature of the disposal site and operations, site-specific
field studies are a necessity.
From an engineering standpoint, only materials which can be bull-
dozed and will remain on slopes without cracking or slumping are suitable
for embankment disposal options. Thus far the only FGC wastes which may
be so applied are those which have been stabilized or rich in sulfates.
Abnormal events will be those which disturb the integrity of either the
compacted waste or the underlying soil layers. In this case, events such
as earthquakes, flooding and slumping due to saturation of subsurface
layers from land rainfall are included.
At the Duquesne Light Company in Pennsylvania, disposal of a 5-10%
solids fly ash slurry in an abandoned coal mine is taking place [411. The
slurry is pumped through a 50 cm borehole to the mine itself; the system
includes three pump holes to dewater the filled areas. Concrete block
dams were constructed to contain the material in the mine. No reports of
the physical stability of the sludge of the sludge or of the system were
made.
Surface mine disposal methods require at least dewatering and
preferably the stabilization of FGC waste to avoid leachate formation and
to permit reclamation to proceed upon a stable surface. Disposal will
occur in layers and involve compaction techniques. The materials must
be plastic enough for contouring by bulldozers. Curing must occur only
after placement, therefore the timing of reclamation/stabilization activi-
ties must be carefully managed. Methods which result in level surfaces
include disposal such as is being performed at Minnkota Power's Milton R.
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Young Station in North Dakota, and mine pit disposal in horizontal
layers.
The normal impacts of surface mine disposal options are strongly
influenced by the requirements of the Surface Mine Control and Reclamation
Act. Because these requirements will set lower limits on the bearing
capacity of the land, determine water tables and surface runoff, the causes
of instability are greatly reduced. Therefore, under normal circumstances
in which these requirements are observed, stability would be assured.
Abnormal events, however, are similar to those that would also
affect dry disposal sites—a disruption of proper operations.
Erosion is a potentially serious question for graded disposal sites.
Cured soil-like stabilized wastes would be as prone to erosion as a
natural soil. A well planned disposal operation must therefore include
anti-erosion techniques such as runoff control and vegetation. Subsur-
face information will play a role in determining good field operations.
Knowledge of the material itself is critical for this disposal option.
Abnormal events could disturb the integrity of the compacted waste and
the underlying soil layers, or both.
Based on unconfined compressive tests [68], the performance of soil-
like fixed sludges appears likely to be satisfactory in bearing capacity for
embankment construction. While existing research has identified several types
of treated materials suitable for use in embankments, a thorough survey
of this application for sludges has not been made. The use of fly ash
embankments has been studied extensively and put into actual use by the
FHA. This is not true for FGD waste studies and more specific research
on shear strength and consolidation characteristics of stabilized sludges
in actual embankments should be performed.
Surface mine disposal methods require at least dewatering and some-
times the stabilization of FGC waste to avoid leachate formation and to
permit reclamation to proceed upon a stable surface. Disposal can be
expected to occur in layers and involve compaction techniques. The waste
materials must be plastic enough for contouring by bulldozers. Curing
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must occur only after placement, therefore the timing of reclamation/
stabilization activities must be carefully managed.
No studies of FGC waste disposal on surface mines have been completed.
Two surface mines with on-site generating stations were disposing of FGC
wastes in mine pits in late 1978. At Minnkota Power's Milton R. Young Station
in North Dakota, filling of a "v-notch" with FGC waste is being conducted
under an EPA-sponsored program. Physical stability and groundwater
quality impacts are being studied by the University of North Dakota and
Arthur D. Little, Inc. At Martin's Lake, Texas, FGC wastes are being
placed in a lignite mine. Data from this program were unavailable as of
December 1978. Additional information will be required to correlate re-
sults of field studies with the results of lab and model tests. An un-
resolved issue regards the effect of acid mine drainage, in contact with
FGD wastes upon stability. To date this has been investigated only with
respect to leachate formation. Also along this line is the stability of
various combinations of fill materials in the spoil pit: FGC waste,
mine tailings, overburden, etc., which has not been reported thoroughly
in the lab or in the field.
Reclamation and Land Use
Disposal of FGC wastes in operating surface or underground mines or
at abandoned mine sites would not require "new" land. The use of aban-
doned mines as FGC disposal sites would appear to be a potentially ideal
disposal practice, especially where used to limit acid mine drainage.
However, disposal in abandoned surface mines, while feasible, is space
limited, especially due to the reclamation requirements of the Surface
Mining Control and Reclamation Act. Disposal in underground mines may be
less feasible (except perhaps in a few isolated cases) due to abandoned
mine conditions.
A recent review of the feasibility of operating mines as disposal
sites concluded that more than sufficient capacity existed in operating
mines for the disposal of large quantities of FGC sludges. From a tech-
nical feasibility perspective, surface coal mines and underground room-
and-pillar coal, limestone and lead/zinc mines were reported to offer the
most promise. Coal mines were considered the most likely candidates due
to capacity and frequent association with power plants.
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A major difference between landfilling of FGC wastes and surface
mine disposal is the ratio of sludge to overburden replacement. The
issues of groundwater contamination and stability of FGC waste disposal
in a surface mine are presently being examined by the University of North
Dakota and Arthur D. Little, Inc. under EPA contract. Results of this
program are not yet available. Essentially, however, the major public
policy land use issues are the same as those discussed for dry disposal
above. Slurried fly ash is being disposed of in an underground
mine in Pennsylvania. Mine dewatering effluent has been reported within
regulated limits for iron, pH and suspended particulates and has reportedly
served to neutralize mine water to some extent.
Given SMCRA requirements, it is reasonable to assume that; the degree
to which the physical or chemical characteristics of FGC waste materials
could affect post-mining reclamation efforts needs to be addressed. The
potential for migration of FGC waste contaminants into surface soils and
vegetation would be of particular concern for surface mines located in
areas of prime farmland since restoration to agricultural production is
a distinct possibility.
The existence of an underground mine would appear to be a more sig-
nificant post-closure land use limiting issue than the disposal of FGC
wastes in the mine. Three areas of investigation relevant to this dis-
posal option are:
• The degree to which FGC wastes can ameliorate acid mine drainage,
• The long term potential for S0_ emissions, and
• The significance, if any, of waste corrosive activity on under-
ground supports, especially where surface stability could be
affected.
None of these issues has yet been studied empirically as of this
writing.
Water Quality Issues
The general discussions on water related impacts for dry disposal
options also apply here. In addition, certain specific issues are
important.
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Deep Mines
Water related impacts associated with deep coal mine disposal of
FGC wastes are extremely difficult to assess because the hydrogeology
of mines is not well understood. Mine disposal is unique compared to
other disposal options in that it has the potential for alleviating an
unrelated environmental problem. The alkaline nature of the FGC wastes
could tend to neutralize acid mine drainage while the sealing of mine
voids might reduce the generation of acid mine drainage.
Lunt et al [29,38] assessed the potential impacts of disposal in
deep mines. FGC wastes disposed of in deep mines would often be beneath
the water table and may interact directly with groundwater. However,
because of the nature of the mine environment, mine drainage migrates
much more rapidly than other groundwater and often follows intricate
paths through voids, fissures, etc. Furthermore, the mine environment
may be aerated resulting in chemical alteration of coal mine drainage,
which typically contains sulfuric acid. Total oxidizable sulfur (TOS)
associated with sulfite-rich wastes is a contaminant of potential con-
cern in leachate. The solubility of TOS in sulfite-rich FGC wastes has
been investigated on a laboratory scale by Arthur D. Little, Inc. in
I [ [ [
relation to varying the Ca and Mg hardness and sulfuric acid concen-
tration of ambient water [29,38]. Special precautions were taken to pre-
vent the aeration of samples (to preserve dissolved sulfite). Sulfite
solubility was generally reported to be about 30-70 ppm. It was found
that the largest influence on sulfite solubility was the ionic strength
of the background leaching solution. Sulfite solubility increased with
the ionic strength in these tests.
Dissolved sulfite would pass through the geologic profile without
attenuation along with the other major soluble anions in FGC waste
leachate [38].
Duvel, Rapp and Atwood[63] have also performed laboratory leaching
tests of FGC waste with a synthetic mine drainage solution. They observed
generation of a black precipitate of iron sulfide and slightly higher
trace metal concentrations with the acid leaching solution than with a
distilled water leach. They discussed various mine disposal scenarios in
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some detail, concluding that complete sealing is necessary in order to
reduce or eliminate the production of acid mine drainage. In view of the
engineering difficulties associated with placing the waste in all mine
voids, the feasibility of complete void sealing has not been demonstrated.
The potential effects of runoff leachate from waters voluntarily
removed from deep mines containing FGC wastes (i.e., pumping to above-
ground storage ponds) have yet to be studied.
Surface Mines
Dry disposal of FGC wastes in the spoil bank of surface mines presents
similar water related impact potential as other dry disposal methods.
Isolation of the wastes from the water table is technically feasible,
and groundwater impacts from typical, well-designed, well-run operations
would be expected to be relatively minor.
A field-scale study of mine disposal alternatives is underway at
Square Butte, North Dakota. One emphasis is on monitoring groundwater
quality. Meaningful results would not be available for some years. Dis-
posal operations at Martin's Lake may also yield useful monitoring data.
Surface impact potential is yet to be studied but is probably analogous
to that for dry disposal.
Disposal on the mine pit floor, which is usually below the water
table, is therefore expected to have a higher potential for groundwater
impacts as described by Lunt, et al. [29,38] for several
surface mine disposal scenarios. FGC wastes are being placed
in "v-notches" in the Square Butte study, providing planned opportunity
for monitoring of potential groundwater impacts in the future.
Other Environmental Assessment Considerations
As for other land disposal options discussed above, potential issues
relating to air quality and biological impacts of FGC waste disposal in
mines have been identified, but subject to no empirical research to date.
A potential for gaseous emissions (e.g., of SO ) from initial reac-
X
tions of alkaline FGC wastes with acid drainage in deep mines has been
Identified by Johnson and Lunt [38]. No lab or field-scale research
on this subject appears to have been initiated. Biological issues for
deep mine FGC waste disposal appear to be largely confined to potential
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impacts derived from water quality changes. No direct investigations
appear to have been initiated, but the relative impact potential in
already disturbed mine environments appears to be minor compared to that
of surface disposal options.
Air quality and biological impact issues for surface mine disposal
are similar to those discussed above for other dry disposal methods. These
issues do not appear to have received research attention to date.
Mine Disposal Demonstration at Baukol-Noonan
The EPA is funding a mine disposal demonstration for FGC wastes at
the Baukol-Noonan mine in Center, North Dakota. The project is being
funded as a part of the EPA's ongoing evaluation of the feasibility of
using the ocean and mines for disposal of FGC wastes.
The wastes placed in the mine are being generated by a 450-MW alkaline
ash scrubbing system at Square Butte Electric Cooperatives (Minnkota Power)
Milton R. Young Station. The Milton R. Young Station is a mine mouth
power plant firing low sulfur lignite. The scrubber system using the
alkalinity present in the fly ash for SO- removal. The fly ash is removed
ahead of the scrubber system in a high efficiency electrostatic precipitator.
It is then conveyed to a storage silo from which it is fed to the scrubber
on demand. The wastes produced which consist of 70-85% fly ash and 15-30%
calcium sulfate are dewatered by thickening and filtration to a solids
content of 70-75% solids. The filter cake is loaded into dedicated 30-ton
trucks for haulage to the mine.
The mine is a surface area strip mine operating with two draglines.
As is convenient, wastes are placed either in the pit bottom after extrac-
tion of coal and before replacement of overburden; or in the v-notches
between spoil banks prior to reclamation. Because of the residual pozzo-
lanic activity of the ash, the wastes harden within a few days alleviating
any stability problems in overburden replacment or reclamation activities.
The demonstration project involves monitoring of various sections of
the mine to assess the impacts of waste disposal. The monitoring of work
is being performed under the direction of the University of North Dakota
with assistance and guidance by Arthur D. Little, Inc.
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4.3 Ocean Disposal
4.3.1 Overview
At present, regulatory posture does not favor ocean disposal initia-
tives nor is ocean disposal of FGC wastes practiced. However, if it
could be practiced, ocean disposal may be an attractive alternative in
the future in the "Northeast. In order to place this disposal option in
perspective, EPA initiated assessment studies on ocean disposal at
Arthur D. Little and the New England Aquarium, and is participating in
conjunction with EPRI and DOE in a program at the State University of New York
To date both efforts have focused on lab-scale and very limited field-
scale studies; further limited field-scale investigations are planned.
Full-scale ocean disposal of FGC wastes has not taken place, limiting
the basis for empirical assessments to the aforementioned studies, and
making definitions of "typical" operating practices somewhat speculative.
4.3.2 Impact Assessment
The EPA-sponsored program being conducted by Arthur D. Little, Inc.
has focused on aspects of the physical stability, water quality, and
biological impact potentials of unstabilized FGC wastes. Results have
been reported by Lunt et al. [29] and Cooper et al. [31].
Two types of lab-scale tests of physical behavior of FGC wastes
in seawater have been completed in the Arthur D. Little program. The
first was a series of "drop" tests to observe FGC waste behavior during
descent in a seawater column. FGC wastes from direct lime processes
exhibited significant cohesion effects in this series of tests, while
gypsum and sulfite-rich dual alkali filter cakes exhibited far less
cohesion. Mathematical modeling to field-scale based on these tests
indicated a wide range of potential water column suspended solids con-
centrations in the immediate vicinity of descending FGC waste masses,
ranging from near zero to in excess of 10,000 ppm [31].
Based on these water column studies and modeling efforts the
Arthur D. Little investigators designed laboratory bioassays using
free-swimming marine zooplankton and finfish reported to be relatively
sensitive to suspended sediments. The results of these tests, performed
at the New England Aquarium, were reported by Cooper et al. [33]:
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• A sulfate-rich FGC waste exhibited acute toxicity only
at suspended sediment levels in excess of 1,000 ppm.
These levels correspond closely to values reported for
a number of very different, naturally-occurring and
man-made sediments for the same organisms.
0 Sulfite-rich FGC wastes exhibited high toxicity under
agitated (tank-scale) mixing conditions. Oxygen depletion
appeared to be the operative mechanism of toxicity. The
applicability of these results at field scale is con-
sidered uncertain.
The potential for sulfite-related oxygen depletion was confirmed
by a series of laboratory dissolution/oxidation studies, also reported
by Cooper at al.[31] . Figure 4.1 shows the results of these tests
for several direct-lime system wastes.
Cooper et al. [31] also reported the results of lab and limited
field-scale observations of the redistribution potential of unstabilized
FGC waste deposits on the ocean floor. As shown in Figure 4.2, modest
currents in a shallow marine embayment were sufficient to redistribute
mounds of FGC waste in less than one hour. Based on these observations
and those in simulated flume tests, the Arthur D. Little investigators
reported that unstabilized FGC wastes appeared to have greater redis-
tribution potential on the ocean floor than certain clay-like soils
and dredged material, and that benthic sedimentation was an impact
mechanism of potential concern for unstabilized material.
Recent efforts under this program have focused on lab-scale tests
to determine long-term effects of major and minor unstabilized FGC
wastes on marine water quality and biota. A series of seawater leaching
studies (under agitated and quiescent leaching conditions) and long-
term exposure studies have been completed in 1978. Preliminary results,
reported in the July through November Progress Reports for the program,
indicate the following:
• Under quiescent conditions, amounts of sulfite-rich FGC
waste that would be toxic (by oxygen depletion) if agitated
in a closed system, can be compatible with prolonged organism
survival in such a system.
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Initial Seawatcr Slurry Concentration
O 25 ppm
A 110 ppm
D 200 ppm
4700 ppm
468
Time (minutes)
Oxygen Depletion vs. Slurry Concentration for Direct Lime Scrubber Waste
Initial Seawater Slurry Concentration
Waste A (110 ppm)
4 Waste B (110 ppm)
0 2 46 8 10 12
% Time (minutes)
Comparative Oxygen Depletion Rates for Different Direct Lime Scrubber Wastes
Source: [31]
Figure 4.1 Oxygen Depletion Rates in Well-Agitated
Slurries of FGC Wastes
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15
10
'x
2 5
a
a
Mound 1
(Right)
Height •——
Width —O—
Mound 2
(Left)
—O—
--a
10
20 30 40
Time of Test (minutes)
50
60
70
Source: [31]
Figure 4.2 Observations of Mounds of FGC Wastes Created
in Shallow Water Environment
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• Leaching studies of Cd, Hg, Ni, Se, and Zn for several
FGC wastes showed release of all but Hg under both
agitated and quiescent conditions to detectable levels
above those present in influent (Boston Harbor) water.
For most of these metals, a correlation with the ash
content of the FGC wastes appeared potentially sig-
nificant. ;
• Exposure studies using FGC waste substrates and water
column levels of metal derived from leaching tests appear
to have produced potentially significant bioaccumulation
of Cd, Ni and Se in invertebrate test organisms exposed
for 45 days to ash-rich wastes. Control organisms and
those exposed to ash-free FGD sludge do not appear to
have experienced similar bioaccumulation.
Continuing work in this program is planned to focus on the
following areas:
• Interpretation of the results of the leaching/exposure
studies with unstabilized FGC wastes,
• Comparable studies with several stabilized wastes (to
be performed by the New England Aquarium under a separate
EPA Research Grant), and
• Limited field-scale studies of potential water quality
and biological effects of unstabilized and stabilized
wastes in a saltwater pond.
The results of the program to date appear to have reinforced initial
concerns about the environmental acceptability of conventional shallow-
ocean disposal (i.e., disposal on the continental shelf) of unstabilized,
sulfite-rich FGC wastes; and both shallow and deep ocean conventional
disposal of unstabilized FGC wastes high in ash and/or trace contaminants.
On the other hand, the program appears to have reinforced the possibility
for development of acceptable dispersed disposal techniques for unsta-
bilized, sulfate-rich FGC wastes low in trace contaminants, either in
shallow or deep ocean situations. Principal information gaps emerging
from the results to date include:
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(1) The implications of stabilization on potential sulfite
and trace contaminant water quality and biological
impacts, and
(2) The applicability of lab-scale results to field-
scale disposal situations.
Studies of the potential for cement-like stabilized FGC wastes to
be disposed of (or utilized) as artificial reefs in the shallow ocean
are being conducted by the Marine Sciences Research Center of the State
University of New York at Stony Brook and the IUCS Corporation. This
research is being supported by several agencies and has been reported
by Duedall et al. [73] and Seleginar [66].
To date, the reported results of these studies have focused on
comparisons of the physical and chemical properties of the stabilized
wastes with those of concrete under seawater exposure conditions. The
investigators have reported favorable comparisons (for the FGC materials)
from the standpoints of physical stability, trace metal leaching, initial
organism colonization in an estuary, and metal uptake by colonizing
organisms. However, the trace contaminant results cannot be considered
definitive in the absence of comparisons with leaching accumulation
reference points for non-anthropogenic substrates. Physical testing
results may also be further amplified by planned testing of FGC wastes
with more typical ash to sludge ratios, as the mixtures tested initially
were reported to be very high in ash content.
Future work under this program is planned to focus on in-situ
reef-building simulations in the shallow ocean. Water quality and
biological parameters are scheduled for investigation.
4.4 Assessment of Present Control Technology
4.4.1 Introduction
It is expected that much of the difference between potential and
actual impacts of the FGC waste disposal options discussed above will be
determined by the degree to which presently available control technology
becomes incorporated as "good design" and "good practice" in typical
disposal operations. Good design and practice could also minimize the
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potential for adverse impacts from abnormal events. Scope and practice
of disposal systems were discussed in Section 2.2.5. A number of control
technologies have been mentioned throughout the above portions of Section 4.
Some of the more important of them are summarized here.
4.4.2 Site Selection
Site selection has been discussed earlier in Section 2.5.1.1. Site
selection may or may not be considered control technology. However,
there is no question that proper site selection could by itself ameli-
orate or eliminate most of the potential disposal impacts discussed
above. Site selection can be used as control technology if the mitiga-
tive combinations and impact issue categories mentioned below are
considered applicable.
Potential Impact Issue Mitigative Site Characteristics
Land Use Proper topography, geology and
hydrology; absence of nearby
conflicting land uses.
Water Quality As above for land use, plus
absence of nearby sensitive re-
ceiving waters (surface or aquifers).
For example, a small stream or
aquifer may impose greater con-
straints than a large stream or
impure aquifer.
Air Quality Absence of "non-attainment area"
and Class I Prevention of Signi-
ficant Deterioration designations
for total suspended particulates.
Biological Absence of sensitive biological
resources.
It is reasonable to assume that sites offering the greatest number
of mitigative characteristics would be the best available for FGC waste
disposal from an environmental standpoint, and could, in some cases,
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make the application of certain control techniques unnecessary that
might be required at more sensitive sites. Exceptions to this generality
would be sites with many advantages combined with one or more major
disadvantages.
A.4.3 Waste Processing Options
In addition to judicious selection of the optimum site, the designer
of an FGC waste disposal system has three waste processing options to
mitigate adverse environmental impacts.
• Dewatering,
• Forced Oxidation, and
• Stabilization.
These have been discussed in Volume 3. Brief comments on their role as
control technology is offered below.
4.4.3.1 Dewatering
As discussed above, dewatering of FGC waste prior to land disposal
can result in major improvements in physical stability and water quality
impacts due to reduced leachate migration and reduced volume of poten-
tially contaminated overlying water (in wet impoundments). As discussed
immediately above, dewatering may be particularly important in the dis-
posal of sulfate-rich FGC wastes. Dewatering, like the disposal of
relatively impermeable, stabilized wastes may require greater consider-
ation of disposal area runoff management, in order to avoid adverse
water quality effects by that route.
4.4.3.2 Forced Oxidation
The intentional production of sulfate-rich, rather than sulfite-
rich FGC wastes, is presently a subject of considerable interest. In
ocean disposal, the sulfate-rich products of forced oxidation would have
the obvious advantage of mitigating the potential for sulfite-related
depletion of dissolved oxygen. This advantage would be shared in land
disposal operations (especially wet impoundments), but its relative
importance is less clear. A dominant question concerning the mitigative
potential of forced oxidation for land disposal is whether or not the
process results in increased or decreased physical stability. Based on
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experience with soils, gypsum FGC wastes comprised of relatively uniform,
sand-sized particles may exhibit considerable failure potential in the
absence of: 1) effective compaction and dewatering, and/or 2) co-disposal
with materials of varying particle size. However, if FGD gypsum is
analogous to phos-gypsum, recrystallization mechanisms occurring in the
disposal pile may improve stability.
4.A.3.3 Stabilization
The advantages of chemical stabilization of FGC wastes as a means
of mitigating a variety of potential impacts have been discussed through-
out Section 4. Stabilization processes are discussed in Volume 3.
Stabilization appears to be highly relevant to the mitigation of land
use issues, including the potential for abnormal events (i.e., disposal
area liquefaction or other catastrophic failure modes), and the suita-
bility of disposal sites for a broader range of post closure uses
requiring Increased bearing strength. Stabilization techniques resulting
in decreased waste permeability can be considered mitigative of poten-
tial water quality impacts due to leachate migration. This factor can
be weighed in balance on a site-specific basis with the opportunities
for disposal area runoff control, since that mechanism could be of
greater importance than leachate for contaminant transfer from stabilized
FGC wastes. It is also unclear whether or not stabilization would reduce
the overall, long-term chemical mass balance of contaminant migration
from a given waste disposal area. In particular, it is not clear that
reductions in long-term trace contaminant availability would take place
when fly ash is used as a stabilization additive to an otherwise rela-
tively contaminant-free FGD sludge.
Cementitious stabilization processes may also be considered
mitigative of the potential for post-disposal fugitive particulate
emissions from dry FGC waste disposal operations.
In ocean disposal, cementitious stabilization may remove liabilities
of FGC wastes as benthic substrates and as sources of sulfite-related
depletion of dissolved oxygen. However, questions of sulfite and trace
contaminant availability, among others, preclude definitive judgment
on this issue at this time.
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4.4.4 Use of Liners
A basic option to control flow of leachates in ponding operations
and generically applicable to dry disposal if site specific conditions
warrant it is the use of liners. Liners are now under study at WES and
by EPRI [15]; these studies were discussed in Section 2.2.1.
4.4.5 Co-disposjil of Wastes and Creation of Waste/Soil Mixtures
Although the term co-disposal is often used in reference to the
creation of disposal mixtures of two waste streams (e.g., FGD sludges
and coal ash), it is used here to imply a broader range of opportunities.
Specifically, for land disposal of FGC wastes, "co-disposal" might also
include the application of technologies for the creation of soil/waste
mixtures. If soils with the proper characteristics are available, the
creation of soil/waste mixtures may be an alternative to the addition
of fly ash where only limited increases in physical stability are desired
in a disposal operation, or where trace contaminant availability needs
to be reduced to facilitate revegetation or decrease water quality impacts.
Traditional co-disposal involving fly ash plus FGD sludge appears to have
substantial advantages over independent disposal in terms of improved
physical stability and (potentially) decreased permeability. This might
be especially relevant to sulfate-rich FGC wastes of uniform particle
size. (See Section 4.4.4 above.) However, in some situations the extent to
which the ash serves as a reservoir of certain trace contaminants could
prove a liability from the standpoint of potential water quality
degradation.
4.5 Summary of Data Gaps and Future Research Needs
A number of programs have been undertaken (and are in progress) by
EPA, DOE, EPRI, and others. These efforts have provided much of the
baseline information for environmental assessment. Provided these
programs continue, additional data and insight permitting better
environmental assessment will be possible.
A number of data gaps concerning FGC waste generation, character-
istics, and utilization have been identified in Volumes 3 and 4.
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In this subsection data gaps and research needs pertinent to environ-
mental assessment of FGC disposal are enunciated. Data gaps apparent
as of early 1979 are listed in a generally descending order of priority
below.
a. Acquisition of field data on the actual impacts of full-scale
disposal operations under varying environmental conditions.
Field-scale monitoring of large disposal operations over a
period of several years is warranted. EPRI's proposed program
at Conesville Plant of Columbus and Southern Ohio Electric is one
such example. EPA is also planning an extensive 2-year study
on characterization and environmental monitoring of sixteen'(16) full-
scale utility disposal sites in support of the further development
of RCRA regulations.
b. A corrollary of (a) above would be the development of correla-
tions and tools of extrapolation to relate existing lab/pilot
scale data on physical stability and water quality impacts to
full-scale field data.
c. Integrated study and evaluation of the environmental trade-offs
in co-disposal of various FGD wastes and various coal combus-
tion ashes. (It appears that this type of initiative could
emphasize laboratory work with limited pilot and full-scale
field verification.)
d. Development of basic data (laboratory and field-scale) on the
biological impact potential of principal land-based FGC waste
disposal options, especially data relating to water-related
impacts of major soluble species and trace contaminants.
Typical questions are:
• What are the biological and health effects of mixtures
of trace metals (in the form found in liquors), such as
zinc, copper, lead, mercury, cadmium or nickel in combina-
tion with selenium in particular, but also in other
combinations?
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• What is the uptake of potentially toxic materials by
vegetation and wildlife associated with disposal
areas?
• What are the levels of ambient concentration of
waste-related potentially toxic materials in
vegetation and surface water that may produce
chronic health problems for wildlife?
The answers to these questions would help implement the
"Environmentally Sensitive Areas" provisions of pending
RCRA regulations. EPA is presently supporting biological
testing work on FGC wastes at Oak Ridge National Laboratory.
e. Development of basic (laboratory and field) data on the poten-
tial for fugitive particulate emissions from areas previously
used for the dry disposal of FGC wastes.
f. Socio-economic impacts of FGC waste disposal on land need to
be better defined.
In the future, FGD waste generation will not be limited to those by
utility systems. Coal utilization in industrial boilers (25 MW or larger)
is also likely to grow substantially. FGD wastes from such industrial
boilers (while analogous in composition to those from utility boilers)
present additional waste management issues due to differences in distri-
bution of generation facilities, in quantity of FGD wastes generated at
each facility and other factors. These issues also require further
evaluations and study.
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5.0 REVIEW OF MONITORING CONSIDERATIONS
5.1 Regulatory Requirements for Disposal
5.1.1 Land Disposal Monitoring
Proposed regulations under the Surface Mining Control and
Reclamation Act of 1977 (SMRCA) and the Resource Conservation and
Recovery Act of 1976 (RCRA) contain provisions for implementing one
or more kinds of environmental monitoring activities which may effect
the disposal of FGC wastes in mines or impoundments.
The recently published proposed rules for a permanent regulatory
program for surface coal mining and reclamation operations (30 CFR) [77]
require both plans and mechanisms for implementing monitoring programs
in the following areas.
• Groundwater monitoring is required of the operator for
both surface and underground operations in order to
ascertain whether the water quality and recharge capacity
have been unduly effected by mining operations [78].
However, details of such monitoring programs, including well
placement, frequency, etc. are site-specific, and will be
decided by the regulating authority on a case-by-case
basis, and incorporated into the reclamation plan [79].
Monitoring is continued until reclamation is complete.
• Surface water discharges must also be monitored by the
operator; this is accomplished with approval from the
regulating authority in conjunction with the NPDES
permit requirements during mining operations [78].
However, the SMCRA surface monitoring must be continued
after active mining has ceased until reclamation for
post-mining uses is complete.
• Water parameters which are to be monitored and for which
limits are set include pH, total iron, total manganese and
total suspended solids [79]. Hydrologic parameters
(i.e., flow) are also required. In addition, other
parameters characteristic of the discharge may be
requested by the regulator.
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• Fugitive dust emissions must be monitored where required in
order to show compliance with applicable air quality standards [79]
Proposed guidelines and regulations for hazardous wastes under RCRA
were published in December 1978 [80]. These guidelines and regulations
are now under review and may undergo significant modifications prior to
scheduled promulgation in late 1979. Under these regulations (discussed
more fully in Section 3) wastes will be tested to determine if they
are hazardous. On the basis of such future tests, FGC wastes may be
classified as non-hazardous or as a special case of hazardous wastes.
However, if the initial characterization of these materials causes some
of them to be classed as hazardous waste [82], then these wastes
together with processing and handling operations will be subject to the
following monitoring requirements:
• The waste itself is subject to an initial detailed analysis
and then must be monitored on a frequent (truckload or batch)
basis for at least physical appearance, specific gravity, and
pH, unless the operator can demonstrate that the state of system
control does not necessitate such frequency [83].
• A groundwater monitoring system, consisting of at least one
well upgradient and three wells downgradient from the disposal
site, must be utilized to check water quality. Sampling fre-
quency will vary from annual to quarterly depending on water
flow [84].
• Minimum analyses of groundwater samples will include conductivity,
pH, chloride, total dissolved solids, organic carbon and the
principal hazardous constituents or indicators found in the
waste. A more comprehensive analysis including the above
constituents plus beryllium, nickel, cyanide, phenols and
chromatographable organics may be required [84].
• The groundwater monitoring program must be set up to continue
for up to 20 years following closure of the site unless it can
be shown that monitoring for that length of time is unnecessary [84],
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5.1.2 Ocean Disposal Monitoring
Regulations establishing the criteria for evaluating permit applica-
tions for ocean dumping and for management of ocean disposal sites have
been promulgated [85]. Part 227 deals with the criteria for the evaluation
of permit applications for ocean dumping of materials, while Part 228
deals with criteria for management of the ocean disposal sites. Ocean
disposal is regulated by the EPA. EPA's current policy is to discourage
ocean disposal especially if alternate means of disposal are available.
However, If ongoing EPA studies indicate ocean disposal is stable, the
situation may change in the future. This discussion on ocean disposal
monitoring is against this perspective. The following points may impact
on the potential for disposal of FGC wastes.
• Where possible, bioassays employing appropriate sensitive marine
organisms, rather than measurement of specific constituents,
are used to assess the impacts of suspended particulate
wastes [86,87].
• Each disposal site must have an impact monitoring program.
Such programs may include a series of baseline and trend
assessment surveys to document and assess changes at the
site. Federal agencies (EPA, NOAA) will have major responsi-
bility for these surveys. Permittees will be required to
participate in the development and implementation of monitor-
ing plans [88].
• Under Part 228.13 [88], guidelines for monitoring programs
are established with respect to:
Timing of surveys, particularly for seasonal variations;
Duration of surveys;
Numbers and locations of sampling stations in dump
and control areas;
Water quality test parameters, including nutrients,
heavy metals, pesticides and other organic materials.
In addition, "analysis for other constituents character-
istic of wastes discharged ... will be included in
accordance with the approved plan of study." [88];
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Locations of sampling points in the water column
for both chemical and biological sampling, and the
number of samples;
Numbers of samples and general locations for bottom
sampling for both biotic and chemical tests; and
Measurements of current and water mass measurement.
The intent and focus of the regulations is to make maximal use
of biotic measurements for monitoring purposes as well as for permit
approval.
5.2 Screening Tests for Solid Wastes
In keeping with an increased awareness of the need to control the
disposal of wastes which may have adverse impacts on the receiving area,
there is a generally recognized need for some type of screening test
which can be performed on the wastes prior to disposal in order to
show whether a waste meets criteria of acceptability established for a
particular disposal situation. The need to conduct such tests on a peri-
odic basis in order to monitor the quality of waste during continuing dis-
posal operations has been addressed in part in the recent RCRA proposed
regulations for hazardous wastes [83]. These regulations contain an Advanced
Notice of Proposed Rulemaking, provisions of which are summarized below.
Under the RCRA proposal such screening tests for solid wastes would
be comprised of three steps or operations:
• Sample pretreatment such as size reduction, physical
stressing or phase separation (for wet solids) carried
out prior to extraction.
• Extraction or exposure to leaching agents. Both the
extraction procedure and the chemical properties of the
extractant will affect the results.
• Testing of the extract (and, in some cases, the eolid phase)
using chemical and/or biological method.
At this time, application of such tests to FGC wastes and definition
of appropriate conditions for each step are still very much in a state of
flux. An ASTM/DOE collaborative program has proposed methods for leaching
of waste materials [89,116]. EPA sponsored a project at Oak Ridge National
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Laboratory (ORNL) to test toxicity of leaches from several wastes includ-
ing FGC wastes. Preliminary results are reported [115] on a limited
number of samples. Investigations are continuing and have not reached
a definite stage to broadly assess whether FGC wastes are non-hazardous
and under Section 4004 or special wastes under Section 3004. Lowenbach
has published a comprehensive compilation of the variety of leaching
test methods which have been used and proposed prior to 1978 [90].
5.2.1 Sample Pretreatment
Sample pretreatment should reflect both the form of the waste
(granular, monolithic block, etc.) and anticipated stresses to which
the waste may be subjected both during and after disposal (compaction,
freeze-thaw, etc.). At present, significant differences which exist
between test procedures are due in part to expectations of pre- and
post-disposal conditions. The recent RCRA-proposed rules indicate
that solids either may be ground (if necessary) to pass through a
9.5-mm standard sieve or may be subjected to specified physical
stresses (multiple blows) in a "structural integrity tester" of special
design [82]. An ASTM proposed leach test (from 1978) did not call for
any size changes since "... The wastes used in this test shall be
tested in the form in which they will be discarded" [89]. The test
procedures used by IU Conversion Systems, Inc. utilize materials from
real or simulated field conditions; for monolithic stabilized wastes
circular slices from a standard Proctor Compactor are used [90]. It is
anticipated that the public comments received by EPA on the proposed
regulation for hazardous wastes will foster further discussion, and
possibly aid in resolution of differences.
5.2.2 Extraction Procedure
Tests employed for FGC wastes have included both elutriation (shake
tests) and column leaching procedures. Both procedures have particular
advantages when properly carried out. For example, shake tests can more
closely simulate surface effects as from runoff, while column leaching
can more closely simulate actual percolation leaching. As yet, there is
no clearly defined rationale for selecting one method over the other, and
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adoption of more than one method may be necessary in order to accommodate
the need for various disposal mode alternative elutriation tests [90],
Likewise, the composition of the leach solution (extractant) is also
under active discussion and investigation. While there appears to be
a feeling that som*1 sort of acidic solution may be appropriate, there
is much controversy over the amount of acid, control of pH and the effect
of the extractant on subsequent tests. The method in the proposed RCRA
regulations for hazardous wastes calls for maintaining a pH of 5.0 - 0.2
by adding a maximum of 4 milliliters of 0.5 molar acetic acid per gram
(dry) of waste solids [82]. This is now under EPA review and may be
modified.
ASTM/DOE program on testing coal combustion wastes is evaluating
EPA and ASTM methods for extraction.
The ocean dumping regulations under MPRSA are explicit, and call
for extraction of the wastes with seawater [85].
5.2.3 Testing of Extracts
In previous work, nearly all tests carried out on extracts have been
chemical rather than biological, due in part to the relative difficulty
of performing controlled biological tests and to the lack of standard
test methods data on appropriate standards for interpretation and com-
parison. As discussed later in this section, this situation is changing
rapidly as more biotic tests are being developed. The recently proposed
RCRA tests address only a very small number of the potentially important
aspects of waste biological effects, and may foster further discussion.
In general, the chemical composition of extracts is measured by the
methods described below. The resulting data are most usually compared
with standards for water quality, such as for drinking water.
The ocean dumping regulations under MPRSA calls for both chemical
and biotic tests of the waste-seawater leachate and solid phases [85],
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The Industrial Environmental Research Laboratory (Research Triangle
Park) of EPA has recently initiated studies at Oak Ridge National Labor-
atory [46] of the applicability of the proposed RCRA extraction procedure
and biological tests to FGC waste materials. The results of these
studies are expected to be available in 1979. Further biological testing
is also anticipated as part of the comprehensive, pending EPA-sponsored
field study in support of definitive RCRA-related regulation of disposal
of utility solid wastes.
5.3 Water Monitoring Methods
5.3.1 Methods for Freshwater
Included under freshwater are groundwaters and surface waters asso-
ciated with landfills and mines.
5.3.1.1 Sampling Methods
An extensive compilation and comparison of methods for sampling and
analysis of groundwater and surface waters at solid waste disposal sites
has been published recently [91]. This manual provides an extremely
useful summary of methods for siting, developing and using well arrays
for groundwater monitoring. In addition, collection and pretreatraent of
surface waters is covered in the EPA [92] and APHA [93] manuals.
Of particular importance for FGC wastes which contain sulfites,
groundwater samples intended for measurement of sulfite or dissolved
oxygen must be taken and protected from atmospheric oxygen by use of a
mechanical pump or a small "grab" sampler.
5.3.1.2 Analytical Methods
There are a number of manuals describing standard analytical methods
and procedures which are applicable to freshwater [91,92,93]. Analytical
methods are undergoing continual improvement in sensitivity as for example
in the use of high-temperature furnaces and plasmas for spectroscopic
measurement of metals and ion-chromatography for measurement of many trace
ionic species.
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5.3.1.3 On-Site Continuous Analyzers
The two:jnajor alternative approaches to the sampling and measurement
of groundwater constituents involve either real-time, in-situ measurement
of components of the sample stream or removal of discrete grab (or
integrated) portions of the sample stream for subsequent measurement.
The in-situ measurement approach eliminates the need for sample
handling (with the attendant possibility of contamination); however, the
number of different monitoring devices (or "probes") is extremely limited
at this time (conductivity, pH, Cl, Na and dissolved oxygen) and, in
general, the long-term accuracy (drift) of those is so poor as to require
frequent calibration checks. Only conductivity represents a real possi-
bility for such monitoring and has been used frequently in groundwater
monitoring programs. For disposal of FGC wastes, the predicted leaching
behavior for all species suggests that concentration changes should be
sufficiently slow so that continuous monitoring would not be required.
5.3.2 Methods for Ocean Monitoring
Ocean disposal is not practiced today. Current EPA policy is to
discourage new ocean disposal initiatives. However, if ocean disposal
is practiced in the future, monitoring of FGC ocean disposal sites can
require comprehensive baseline and trend surveys covering all aspects of
the ocean environment, and may include some shorter-term studies relating
to dispersion ("initial mixing") of the waste immediately after dumping [80].
Because of factors such as accessibility and cost for multiple sampling
points in oceanographic studies, the development of on-site continuous
monitors for parameters of interest such as salinity, pH, temperature
and turbidity has proceeded much farther than for equivalent groundwater
tests. Still, measurements of most chemical and many biological parameters
of interest, and especially those related to hazardous characteristics
must involve discrete laboratory tests.
5.3.2.1 Sampling Methods
Equipment to obtain samples of water from various depths (for example
Nansen bottle and Van Dorn samplers) and samples of bottom sediments
(grab and bucket samplers as well as corers such as the Phleger) are
well known and widely used in the United States [29,95].
5-8
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5.3.2.2 Analytical Methods
Methods for the chemical and physical analysis of water and solids
from ocean sampling have been described extensively. A survey of some
state-of-the-art methods for trace level measurement of metals and
organics has shown that many of the methods used in freshwater measure-
ments can be applied, with some modifications, equally well to seawater
[95].
5.3.2.3 On-Site Continuous Monitors
As noted previously, a variety of on-site monitoring devices have
been developed for ocean water-column monitoring. Parameters include
salinity, temperature, current velocity, pressure and turbidity [29].
Gathering such baseline data without need for active sampling and
analysis may be useful for disposal and dispersal measurement for FGC
wastes.
5.4 Fugitive Emissions Monitoring
Measurement and abatement of fugitive emissions as stipulated under
the Clean Air Act are required under both the SMCRA (Part 816.95) and
RCRA (Part 250.42-3) proposed regulations [9,77]. The ambient air measure-
ment methods are given in 30 CFR 780.14 and include use of "Hi-Vol"
samplers.
5.5 Biological Monitoring
5.5.1 Introduction
Considerations of biological monitoring for FGC waste disposal
operations can be grouped into three categories:
• Baseline (pre-disposal) monitoring requirements,
• Pre-disposal bioassay testing, and
• Compliance monitoring during and after disposal operations.
In general, the use of biological monitoring as a regulatory tool is a
relatively new development. Accordingly, there is little practical
experience with the application of criteria and techniques discussed
below. For ease of interpretation, the discussion is organized to
correspond to the particular regulations that are the source of mon-
itoring requirements in each of the three broad categories just identified.
5-9
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5.5.2 Predisposal Baseline Surveys
Two bodies of federal regulations require monitoring of baseline
ecology at prospective disposal sites prior to their use for disposal.
These regulations are: those derived from the Surface Mining Reclamation
and Control Act, and those derived from the Marine Protection Research
and Sanctuaries Act. By definition, these regulations would be applicable
to only two of the disposal options considered throughout this report,
i.e., disposal in surface mines and disposal in the ocean.
Regulations to implement the Surface Mining Reclamation and Control
Act are still emerging as of this writing. The proposed rules for the
permanent regulatory program published September 18, 1978 [77] indicated
that the following types of baseline biological data could be required
of applicants prior to the commencement of mining operations:
• Identification and vegetative mapping of proposed vegetation
reference areas, and
• Specific species inventory, habitat discussion, and protection
plans for fish and wildlife resources.
Neither of these requirements would be directly related to the use
of the surface mine for FGC waste disposal. Rather, they would be
required of the applicant for a proposed mining operation. However,
the effects of FGC waste disposal on the resources identified in this
base line survey, should such disposal be practiced as part of an
eventual reclamation plan, would be of relevance. Requirements for
this type of post-operations survey are discussed in Section 5.5.4 below.
The final revisions of regulations and criteria for ocean dumping,
published by the EPA on January 11, 1977 [85] include potential require-
ments for the accomplishment of extensive base line monitoring of
biological parameters as part of the disposal site designation process
(Section 228.4 of the regulations). Criteria to be investigated in
these types of surveys are not specified in great detail by the regu-
lations but include location in relation to breeding, nursery, feeding,
or passage areas of living resources in adult or juvenile phases and
potentiality for the development or recruitment of nuisance species in
the disposal site. If FGC wastes were to be disposed of in an existing
5-10
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site, this type of monitoring requirement would not be applicable. If,
however, a new site was proposed for FGC waste disposal, then such pre-
disposal monitoring could be required. These surveys are identified as
responsibilities of the federal government (EPA has primary responsibility
with support from the National Oceanic and Atmospheric Administration).
5.5.3 Predisposal Bioassay Testing
Bioassay testing to measure the apparent toxicity of wastes has
become an increasingly important tool in the evaluation of solid waste
disposal options. In several cases, bioassay results are becoming
formal considerations to complement or replace traditional measurements
of potential toxicity based on physical or chemical evaluations. Four
bodies of federal regulation have potential implications of this type
for FGC waste disposal:
• Resource Conservation and Recovery Act,
• Toxic Substances Control Act,
• Federal Water Pollution Control Act, and
• Marine Protection Research and Sanctuaries Act.
Unlike the criteria for baseline surveys described above, requirements
of bioassay testing under these regulations would be specifically applicable
to FGC wastes, either on a generic or case-by-case basis.
Throughout this report the importance of the potential designation
of wastes as "hazardous" under RCRA has been emphasized. The Act requires
EPA to consider the toxicity and bioaccumulation potential of wastes in
reaching a determination of whether or not that waste is hazardous. EPA
has been developing test protocols that emphasize certain aspects of the
acute and chronic toxicity of wastes, measured for specific types of
organisms. More complex considerations, such as bioaccumulation and
carcinogenicity, have been given less testing (and more theoretical)
emphasis because of the relatively great difficulty in achieving test
results that have a high degree of certainty [95]. The proposed RCRA
hazardous waste guidelines published on December 18, 1978 [80, Part
250.15] list tests for mutagenicity and a theoretical estimation method
for bioaccumulation which are to be applied to specific wastes (FGC not
5-11
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included) if an applicant wishes to demonstrate that such waste does not
have adverse biological effects. The bioaccumulation estimation is one
that relies on measurement of waste partition coefficients, and is
more relevant to lipid-soluble organic substances than to FGC wastes.
EPA has also published an advanced notice of proposed rule making
[80] in which public comment is requested regarding the
application of specific biological tests for toxicity including muta-
genicity, DNA repair and bioaccumulation. It is not clear whether
"special wastes" such as FGC wastes would be subject to these tests.
This Notice proposes a few relatively standard bioassays involving the
use of one type of zooplankter, and terrestrial vegetation [80]. The
resolution of this type of testing requirement could have important
implications for the degree of biological monitoring required of FGC
wastes.
The Industrial Environmental Research Laboratory of EPA
has current contract programs, both at Oak Ridge National Laboratory
and at Bionetics Division of Litton Industries, to investigate the
effect of FGC wastes, among other materials, on various proposed bio-
logical test systems.
ASTN Subcommittee D19.12 (Pollution Potential of Leachates from
Solid Waste) is also active in the area of biological testing of solid
waste extracts, and currently has two Task Groups working on muta-
genicity and biological activity protocols [96].
Testing requirements under the Toxic Substances Control Act (TOSCA)
could be applicable to FGC wastes in conjunction with their prospective
utilization. While this is not strictly a disposal consideration, the
test protocols and implications can be considered similar to those
described immediately above for RCRA regulations.
Bioassay testing is assuming greater importance in the imple-
mentation of the Federal Water Pollution Control Act as emphasis moves
to the regulation of "toxic" or "priority" pollutants. If effluents
from FGC waste disposal operations are regulated as point-source dis-
charges under NPDES permitting procedures, permit review agencies have
the opportunity to apply bioassay tests to the effluent in addition to
5-12
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(and in some cases, in place of) traditional chemical analyses. To
date, there has been some use of this option in federal implementation.
Specifically, the regulations governing ocean outfall discharges have
described acute toxicity testing requirements, coupled with possible
chronic toxicity and accumulation tests. The bioassay approach is
appearing in various state and local level programs as well. For example,
a Colorado guideline undergoing public hearing in November 1978 allowed
the use of bioassay results obtained by testing ecologically or econ-
omically important and sensitive species as an alternative to other
existing effluent limitations for many toxicants. Ohio regulations
indicated that all pollutants or combinations in a discharge cannot
exceed one-tenth the 96-hour LC^Q for representative aquatic species.
It also includes a more stringent application factor (1/100) for per-
sistent toxicants. As more states assume implementation responsibilities
and NPDES permitting authority, the likelihood of FGC wastes undergoing
aquatic bioassay evaluations is expected to increase.
The EPA ocean dumping regulations [85] require bioassay testing
of "appropriate sensitive marine organisms" with candidate wastes for
ocean disposal. This would include testing with representatives of
phytaplankton or zooplankton, crustacean or mollusk, and fish species
at the EPA's discretion. If FGC wastes are considered to have a "solid
phase," similar testing with benthic organisms (filter feeders, deposit
feeders, and burrowers) would also be required. The test requirements
for ocean disposal are determined on a case-by-case basis, but their
scope includes consideration of acute and chronic toxicity as well as
bioaccumulation potential.
5.5.4 Biological Monitoring for Disposal Operation Compliance
Present regulations under three statutes define biological moni-
toring that would be applicable to ongoing disposal operations. The
statutes are: Surface Mining Reclamation and Control Act, Federal
Water Pollution Control Act, and Marine Protection Research and Sanc-
tuaries Act.
5-13
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If FGC wastes were disposed in surface mines, the effects of this
disposal would be evaluated in the context of the overall mine rec-
lamation effort. Accordingly, the types of regulations under con-
sideration by the Department of the Interior could require continuing
monitoring of the success of revegetation efforts. The proposed final
rules on Surface Mining Reclamation and Enforcement Provisions [77] in-
cluded a requirement to evaluate vegetative species diversity, distribution,
seasonal variety and vigor. For the production of agricultural crops,
the crop production on a mined area compared to that of a reference
area would be evaluated. For determining compliance, production would
be considered "equal" on the mined area if it equaled 90% or more of
that on the reference area for a minimum of two growing seasons. Base
line survey requirements for the determination of reference areas are
discussed above in Section 5.5.3.
State initiatives in the enforcement of the Federal Water Pollution
Control Act sometimes include biological monitoring requirements. For
example, Florida measures effects on the "biological integrity" of the
area receiving an effluent discharge as an alternate index on environmental
impact [97]. The Florida criteria indicate that the Shannon Weaver
diversity index for benthic macroinvertebrates cannot be reduced to
less than 75% of background levels, determined by triplicate sampling.
This type of criteria is not yet common. However, some local enforce-
ment agencies, such as the Erie County Department of Health in
Pennsylvania, use combined biological and chemical monitoring as a
means of "red flagging" potential leachate problems from solid waste
disposal sites. Because, in some cases, this approach may be less ex-
pensive than monitoring an increasingly long list of chemical constituents,
it is reasonable to expect more enforcement agencies to consider its use.
Site monitoring during disposal operations is also a continuing
responsibility of the federal government under the Marine Protection
Research and Sanctuaries Act. Ocean disposal of FGC wastes would be
subject to such monitoring. Biological considerations would include
the following:
5-14
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• Absence from the disposal site of po]lution-sensitive
biota characteristic of the general area, and
• Progressive, non-seasonal changes in composition or
numbers of pelagic, demersal or benthic biota at or
near the site.
Continued use of a disposal site could be contingent on the results of
these monitoring programs [85].
Biological testing is assuming increasing importance in assessing
the real environmental impacts on disposal sites, and for providing
guidance on long-term genetic and toxic effects. At this time, research
support is needed in the development of improved biological tests which
can be applied to samples obtained from laboratory or field monitoring
studies. Also of high priority is the need to establish appropriate and
acceptable protocols for the predictive testing of solid wastes. Lesser
priorities concern the need to support R&D field studies for testing and
improving monitoring tests.
5.6 Monitoring of Physical Properties
To date virtually all of the planning and implementation of
monitoring programs for FGC waste disposal has centered around the
concentrations of and transport of substances which are potentially toxic
or hazardous to the health of various life forms. However, the potential
impacts which the physical stability of emplaced FGC wastes may have on
both site operations and post-operational use of the site warrants some
consideration of possible efforts to monitor appropriate physical properties.
At present, there are no federal regulatory requirements for monitoring
physical stability of materials involved in FGC waste disposal. Should
such monitoring become desirable, the Army Corps of Engineers has estab-
lished procedures for in-situ physical tests, as part of the guidelines
for dam inspection, which may be appropriate for FGC materials.
In-situ measurements which may be useful in assessing stability
of emplaced wastes include changes in strength and degree of saturation
as a function of depth. The techniques for making these measurements
are used in civil engineering programs, such as dam inspection, and may
5-15
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need to be brought to bear on FGC wastes in order to ascertain the extent
to which these waste behave in a manner analogous to similar soils.
5.7 Post-Operational Monitoring
The type and extent of post-operational monitoring needed for FGC
disposal sites will vary markedly as a function both of disposal operation
and of intended end use of the land. For example, regulations governing
both disposal of hazardous wastes and coal mining operations may impose
quite different monitoring requirements.
Leaching of potentially harmful substances from the wastes into
groundwater is expected to be a major long-term impact for any site which
is not covered or otherwise rendered impervious to generation and perco-
lation of leachate. Because of the relatively long time scale during which
such leaching occurs, post-closure monitoring of groundwater in close
proximity to the site for an extended period will be necessary in order
to detect such effects. The proposed regulations governing disposal of
hazardous wastes [80] recognize this problem, in part, by requiring that
a post-closure monitoring program be maintained for a period of up to 20
years at the same level (frequency and analytical requirements) as was
employed during active operations. The proposed surface mining regulations
[77], which do not address FGC wastes specifically, indicate that a
monitoring program, acceptable to the regulatory authority, must be main-
tained until the groundwater recharge capacity and quality has returned
to levels stated in the permit. No limit is placed on this effort.
If disposal operations have resulted in potential disturbance to
living species in the area, and these were included in predisposal base-
line assessments, both for disposal in the ocean and in mines, then some
form of biological monitoring would be required after operations had
ceased in order to determine that the area was returned to any level of
"life-support" required by the regulations.
If post-disposal land use differs from the original use, as for
example, diversion to alternative agricultural purposes, then a redefini-
tion of monitoring requirements to include biological samples, for example,
would likely be required. Such changes would have to be dealt with on
a case-by-case basis.
5-16
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The technical details of such post-operational monitoring activities
would likely resemble those utilized during operations. It would be
expected that accumulation and evaluation of the operational monitoring
data might allow selection of key indicator parameters or species for
post-operational monitoring.
5.8 Data Gaps and Future Research Needs
FGC waste disposal practices will be subject to monitoring to the
extent required by environmental regulations. As such, the principal
impetus for monitoring is regulatory, and thus the needs are best described
against the perspective of regulatory requirements.
Broadly speaking, biological testing and monitoring is assuming
increasing importance in assessing the real environmental impacts on
disposal sites, and for providing guidance on long-term genetic and toxic
effects. At this time, research support is needed for the development of
a broader base of improved biological tests which can be applied to samples
obtained from laboratory or field monitoring studies. Also of high pri-
ority is the need to establish appropriate and acceptable protocols for
the predictive testing of solid wastes. Lesser priorities concern the
need to support R&D field studies for testing and improving monitoring
tests.
To date, most monitoring data gathered has been derived from
chemical rather than biological tests. As pointed out in Section 5,
biological and bioassay tests are becoming increasingly important for
assessing the real impact (as opposed to inferential impact based on
chemical tests alone) on the ecology at the disposal site itself, as
well as for providing some guidance as to long-term genetic and toxic
effects of wastes proposed for disposal. Both of these areas are
extremely important to the acceptability and eventual disposition of FGC
wastes. In each of the technical areas discussed below, the needs
related to biological testing are of high priority. The technical
areas are:
5-17
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• Indicators and Measurement Parameters - Selection of appropriate
parameters and species for monitoring is the key element in any
monitoring program. An understanding of the potentially
hazardous characteristics of FGC wastes allow selection of
candidate organisms for controlled testing. This activity is
closely coupled to improvements in methodology.
• Measurement Methodology - Methods for carrying out biological
tests for acute and chronic toxic and accumulation effects and
for detecting genetic effects are now under active development
in connection with many EPA programs in water pollution. These
efforts should be supported in order to bring the state of the art
in biological testing up to the level of chemical testing, in
terms of applicability, sensitivity, specificity and repeatability.
• Sampling Methodology - The ability to obtain representative
control and experimental samples, whether of groundwater or of
species within the localized ecosystem, is essential to carrying
out valid baseline and trend assessments. The major problem of
predicting local groundwater flow patterns in order to plan and
implement an effective groundwater sampling program, plagues FGC
waste disposal in the same way as other solid waste disposal
programs. Additional effort on improved methods for predicting
and tracing groundwater flow is warranted now because of the
rapidly expanding programs related to RCRA.
• Field R & D Programs - Additional support to ongoing and upcoming
field monitoring test programs should be considered. It is
especially important to include tests of appropriate biological
monitoring systems in order to provide opportunities for
correlation of chemical and biological data under controlled
field conditions. In addition, in-situ tests of physical
properties of the emplaced FGC wastes should be considered at
a controlled field site. Tests of the variation of strength,
density and saturation as they vary with depth of overburden and
with time would be extremely valuable, not only for the
correlation with laboratory tests, but also as indications of
the utility of such measurement for monitoring stability.
5-18
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Relationship With Other Monitoring Programs - Recent publications
have pointed up the complex interrelationships of the multitude
of environmental monitoring programs presently conducted by
various Federal agencies [98,99], There is increasing need for
and emphasis on obtaining valid correlations among independent
systems through increased implementation of quality assurance
programs, and on avoiding excessive duplication of efforts. The
EPA FGC waste disposal activities and programs are at the
interfaces between a number of Federal agencies and program
areas, and, hence, may afford the opportunity to provide some
of the needed correlative activity.
Development of suitable and acceptable protocols for pretreatment
and extraction steps for predictive tests of solid wastes is of
high priority as discussed in Section 5 of this volume. Such
procedures are essential for testing and qualifying FGC wastes
in all forms (stabilized and unstabilized) under proposed RCRA
regulations.
5-19
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6.0 REVIEW OF DISPOSAL ECONOMICS
6.1 Introduction
The economics of FGC waste disposal are quickly becoming one of the
most important factors in the implementation of particulate control and
FGD systems. Studies of FGC process technology and evaluations of
specific FGC process applications now routinely incorporate analyses of
associated waste processing and disposal costs. With the increasing
importance of waste disposal and the growing emphasis on environmentally
sound waste disposal practices, a number of conceptual design and cost
studies have also been undertaken sponsored by governmental agencies and
private organizations, notably the EPA and EPRI. These studies have been
basically of two types:
• First, generalized costing to develop comparative economics for
various waste disposal options, including current practices and
potential alternatives. Such studies have been performed by
TVA [23,27,102,103,104], Aerospace [37,105-109], Michael Baker
Associates [9] and ADL [29]. These have focused on FGD wastes,
including stabilized wastes. Fly ash waste disposal has been
studied by NUS [HO] for the Utilities Water Act Group (WAG).
• Second, economic impact analyses to estimate the effects of
various FGD waste disposal regulatory scenarios on the utility
industry. Two impact studies have recently been performed by
Radian [111] and SCS Engineers [112]. Reports on both of these
studies are now in draft form. Additional studies have been under-
taken by DOE regarding the possible impact of RCRA on waste disposal
costs.
In addition, site-specific and system-specific studies have been performed
by a number of utilities, engineering firms and other consulting organiza-
tions. However, this assessment of the economics of waste disposal is
based only on the generic studies mentioned above.
6.2 Generalized Waste Disposal Cost Studies
6.2.1 Description of Studies
6.2.1.1 Overview
Table 6.1 summarizes the general scope and cost bases for the
generalized cost studies performed by TVA, Aerospace, Michael Baker
6-1
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Table 6.1
Summary of General Conceptualized Cost Studies for the FGC Waste Disposal
Contractor
T»A
Aeroepece
Michael laker
ADL
True of
Com.
Sponeor Hlsh S
DA Uaeetone
EPA Liaeetone
XPKI Llae
EPA LJ»e
Scrubber Mode of Operation 1
Forced SO, Dry Wet
Oxidation SO, Only + AaS Landfill Pond
Llaeatone / / / /
Liawtone / (/) / /
-
/
tteooeel Optlone Coneldered
Surface Underground Ocean
Mine Mine
/
-
/ / J
Ho. Caeaa
150*
-30°
4
16
&aae Tear
1979/80
1976.77
1976
1977
Kafarence*
23, 27, 102, 103,
104
37, 105, 106. 107
108. 109
9
29
ms
OKAC
Fly Alb
Only
I
10
Four caaaa lacluda llae •crabbin|.
b Included only for forced oxidation.
c MriMX of cuei atudied varies ulth report.
1974
Source: Arthor*D. Little. Inc.
-------
Associates, and Arthur D. Little. Table 6.2 gives the basic design and
operating assumptions for each of these studies. Where the studies are
still ongoing, the base years for the most recently published cost esti-
mates are shown.
Unfortunately, the design and operating assumptions in these economics
studies as well as the battery limits for the disposal systems differ. Also,
costs are generally presented in lump sum fcrm covering the entire waste
processing and disposal facilities. Hence, direct comparisons of cost
estimates are difficult at best. In this regard, efforts are now under
way to develop a standard cost basis for future cost analyses of FGC
systems and disposal operations prepared by EPA contractors.
In developing any generalized costs for waste disposal, it is also
important to recognize the fact that it is frequently difficult to totally
divorce the waste disposal system from the scrubber. This is particularly
true when comparing systems with different types of ash collection or
scrubber technology (e.g., forced oxidation), and it may be equally
important when developing the design basis for the waste processing
facilities. In most cases, waste processing will be coupled directly to
FGC scrubbers or thickeners, and the waste processing plant must be
capable of handling the short-term sustained peak loads expected for the
FGC system itself, especially with regard to variations in coal sulfur
and ash content. Such overdesign needs to be factored into either the
capacity of the equipment itself and/or provision for a buffer between the
FGC system and parts of the waste processing plant (such as interim storage
of filter cake and ash). It is best, therefore, to evaluate waste dis-
posal in the context of total FGC system costs rather than independently.
In addition to the generic and generalized cost studies, cost data
is now beginning to be published on full-scale commercial disposal opera-
tions as new systems come on-line and more accurate accounting of waste
disposal costs is employed. These cost data will be reviewed as they
apply to each of the disposal methods discussed. The EPA is also fund-
ing two disposal demonstration projects which will provide additional
cost information—a landfill impoundment at LG&E's Cane Run Station and
a mine impoundment at the Baukol Noonan Mine in North Dakota.
6-3
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6.2
Summary of Basic Assumptions for General Cost Studies - FGD/FGC Wastes
TVA
POKER FLAMT
Boiler Site (Ho. zvi)
Heat Kate (Btu/kHh)
location
Service Life (Tr«)
Load Factor (X) - First 10 Tre
- Llfatlac A»g.
Base Case
300
Variation*
Aerospace*
200 & 1500
• 9,000 •
• Mldveetern
30
SO
48
IS, 20. 25
1,000
9,000 • 9,300
30
50
Michael taker
2 x 500
10,000
Eastern
30
75
ADt
500
(0.85 Ib Coal/kHh)
Eastern
30
80
I
•tr-
COAL FIOFEKTIES
Sulfur Content (X)
Aah Content (X)
Beating Value (Btu/lb)
SOBBBBX ST8TEM DESIGB
Alkali
Node of Operation
Alkali StolchloMtry
3.5
16
2.0 a 5.0
12 t 20
10.500 •
Conventional a Forced Oxidation •
SOj + ash SOj Only
(Conventional Uavatone - 1.5
JLinestone Forced Oxidation - 1.1
(Line - 1.1
• To 1.2 lb/M( Btu •
3.0
12 & 14
12,000 e 10,560
Llnutone
[Conventional for SOj + Ash 1
[Forced Oxidation for SOj Only]
(Conventional Llmsetone - 1.5 t 1.25
lUaMtone Forced Odd. » 1.0 t 1.5
85X 4 901
3.5
15
12.000
S02 Only
1.10
3.0
10
Conventional
802 Only
1.10
90X
KOKXSC FACTOU
Coat Tear
Capital Charge Factor
System Battary Limit*
1979/M
0.164 0.174, 0.179. 0.194
Heat* Procesalnj + Dlapoaal
1976 4 1977
0.18
Haste Disposal Only
T
0.18
Haate Processing + Dlapoaal
1977
0.17
Haaee Disposal Only
*The bases for costs varied over the course of the 5-year stadias.
Source: Arthur D. Little, Inc.
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6.2.1.2 TVA (EGG Wastes)
The continuing FGC waste disposal cost study being performed by TVA
under contract to EPA has the widest coverage with respect to the number
of different wastes and disposal options considered. A generalized
computer costing model has been developed similar to that for scrubber
system costing. To date, over 150 cases have been analyzed.
Thus far, two reports [23,27] and at least two papers [102, 103] have
been published summarizing results of this work. The first report [23]
covered the disposal of both stabilized and unstabilized wastes from con-
ventional direct lime and limestone scrubbing systems. In this initial
analysis a total of 121 variations on system design and operation were in-
cluded. Four base cases were established for new 500-MW plants burning high
sulfur coal (3.5% sulfur, 16% ash, and 10,500 Btu/lb heating value) fitted
with direct limestone scrubbing for simultaneous S02 and particulate control.
Each base case involved a different type of disposal: one for disposal via
wet ponding of unstabilized scrubber discharge, one for wet ponding of thick-
ened waste stabilized by Dravo's Synearth process, and two for dry
impoundment of filtered wastes dewatered via the Chemfix and IUCS process.
Variations on these base cases were costed to evaluate the effects of
power plant size and age, coal properties, disposal site distance, scrubber
process conditions, stabilization additive rates, mode of waste transport,
and types of pond liners for wet ponding of unstabilized wastes. Costs
were also prepared for dry impoundment of unstabilized waste.
Capital cost estimates were prepared in 1979 and first-year operating
cost etimates on 1980 dollars. The economics are presented on an inte-
grated system basis (including both waste processing and disposal)
starting at the scrubber battery limits. Annual revenue requirements
for the four base cases range from 0.94 mills/kWh to 2.00 mills/kWh
compared with scrubber costs of 3.38 mills/kWh.
In a continuation of this study, TVA has recently completed analyses
of 32 additional cases involving dry impoundment of ash blended unstabilized
wastes (scrubber preceded by a high efficiency electrostatic precipitator)
and combined fly ash and gypsum from forced oxidation systems with simul-
taneous particulate control. The draft of this report [27] is now in
6-5
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review; however, a summary of the results of both this and the initial
study has been published [102].
This work performed by TVA has involved engineering cost estimates
for generalized conceptual designs, focusing on gross effects of major
parameters on waste processing and disposal economics. As such, simpli-
fying assumptions were made with regard to the engineering properties of
various different types of wastes and equipment design parameters. The
properties and equipment design bases are now being reviewed and modified
to more closely reflect variations in different types of wastes, and efforts
are being made to provide cost estimates on a modularized basis to allow addi-
tion and deletion of processing units as appropriate. And the study is being
extended to include disposal of dewatered wastes in area surface mines.
The costing model has also been used [104] to evaluate the potential
cost effectiveness of employing the thickener/clarifier combination being
investigated by Auburn University in place of a conventional thickener
or thickener/filter combination for waste dewatering. The results indicate
that potential cost savings of up to $0.75/dry ton of waste (ash + FGD)
may be realized if target performance is achieved.
6.2.1.3 Aerospace (FGC Wastes)
In 1974 Aerospace [105] first began developing cost estimates for wet
ponding of unstabilized wastes in lined ponds and dry impoundment of stabil-
ized wastes as a part of its ongoing contract with EPA. Since then, these
estimates have been revised and additional cost data published {37,106-109]
The latest figures were published in 1978 [113] and reflect second-quarter
1977 dollars. Costs are based upon a 1000-MW power plant burning moder-
ately high sulfur coal (3.5%) using a lime scrubber for combined S02 and
particulate control. For ponding, wastes are assumed to be piped directly
from the scrubber to the pond. A variety of different types of ponds have
been considered, including ponds with natural liners, synthetically-lined
ponds, and a novel approach involving ponding with underdrainage wherein
the percolate is collected and returned to the scrubber. The purpose of
this latter approach is to improve the density of the settled solids and,
at the same time, control leachate escape.
6-6
-------
In 1977 [109] and 1978 [113], Aerospace also published cost estimates for
producing wall-board grade gypsum from limestone forced oxidation systems
to compare costs with conventional limestone scrubber waste disposal.
In this case, a high efficiency electrostatic precipitator was included
ahead of the scrubber for particulate removal.
Aerospace has recently begun investigating, under contract to EPA,
surface disposal of gypsum. Costs of disposal are being estimated as a
part of this effort.
6.2.1.4 Michael Baker Associates (FGC Wastes)
Michael Baker Associates recently completed a study of the state
of the art of FGC waste treatment technology [9] for EPRI. As a part of
this study, cost estimates were prepared for four cases to compare the cost
of disposal of untreated wastes with corresponding stabilized materials.
One pair of cases compares wet ponding of thickened wastes (unstabilized vs.
stabilized via a Dravo-type process) , and the other compares dry impoundment
of filtered wastes (unstabilized ash blended vs. stabilized via admixture
of ash and lime). The basis for the economics is two 500-MW boilers firing
high sulfur eastern coal (3.5% S) equipped with high efficiency electro-
static precipitators for particulate control and conventional direct lime
systems for S02 control. Costs were prepared battery limits at the
thickener underflow with processing costs based upon vendor quotations
of package systems. While not stated, it is assumed that cost estimates
are in mid-1977 dollars. The incremental revenue requirements as first year
costs for waste stabilization were estimated to be $1.40/dry ton of waste
(ash + FGD) for dry impoundments and $4.00/dry ton for wet ponding.
6.2.1.5 Arthur D. Little (FGC Wastes)
As a part of an ongoing study to evaluate the feasibility of ocean
and mine disposal of FGC wastes, ADL prepared general disposal cost
estimates for conceptualized systems [29]. A total of 16 cases were
evaluated, six for mine disposal and ten for ocean disposal. The six mine
disposal cases included four involving dry impoundment in surface area coal
mines and two for hydraulic backfilling of underground coal mines. The
ten ocean disposal alternatives included four on-shelf disposal cases and
6-7
-------
six deep ocean disposal cases. Both stabilized and unstabilized wastes are
included. Costs were prepared battery limits at the discharge of the
dewatering or waste processing equipment and are presented in first
quarter 1977 dollars. Revised cost estimates for the most promising
options are expected to be published in early 1979.
Also, as a part of this program, a mine disposal demonstration
project for FGC wastes from an alkaline ash scrubbing system is being
conducted. The scrubber system is at Square Butte Electric Cooperative's
(Minnkota Power) Milton R. Young Station, North Dakota; and the wastes
are being returned to the Baukol Noonan mine. The cost of the full-scale
disposal operation is being tracked to assess overall mine disposal
economics.
6.2.1.6 NUS Study (Fly Ash)
A study was performed in 1975 by NUS for the Utility Water Act Group
(UWAG) to make a comparative economic evaluation of the costs associated
with a dry fly ash disposal system versus a wet system for new power
plants [110]. While actual costs are highly site- and system-specific,
a number of baseline assumptions were made to facilitate generic com-
parisons. The design basis was a 35-year plant life with a lifetime
total fly ash production of 8.35 x 10^ metric tons. The wet pond would
require a total area of 1.35 square kilometers (340 acres) and would
consist of an excavated, unlined area surrounded by 9.1-meter (30-foot)
containment dikes with a 5/1 slope. The dry impoundment area was esti-
mated to require a cleared area of 0.95 square kilometers (240 acres)
where ash would be deposited to a depth of 9.1 meters (30 feet) and
contained by dikes with a 5/1 slope. The cover for the wet pond would
be approximately 1.5 meters (5 feet) of water; the dry impoundment would
be covered by 1 meter of compacted earth. In this regard, the design/cost
basis was a geographic location where annual precipitation roughly equalled
evaporation, a rare occurrence for most disposal sites. Thus, only the
dry impoundment area includes a rainfall treatment facility.
Based upon these assumptions and using the available data, the capital
cost for the wet pond was estimated to be $22.2 million compared with
6-8
-------
$7.8 million for the dry impoundment (1979 dollars - escalated from 1974
costs @ 8%/yr); both included land cost at $3000/acre ($750,000/square
kilometer). The annual operating cost for the dry system was also esti-
mated to be significantly less expensive than the wet system—cost of
$18.00 for wet ponding per ton versus $9.50 for dry disposal (1979
dollars). A key element in the cost of disposal is that associated
with run-off treatment. However, many site-specific factors could
change this and other aspects of ash disposal costs.
6.2.2 Disposal Cost Estimates for FGD/FGC Wastes
6.2.2.1 Land Disposal
Three of the four studies discussed above have dealt exclusively
with land disposal of FGC wastes; the fourth, performed by Arthur D.
Little, has covered both land (mine) and ocean disposal. All of these
studies address applications of FGC systems to relatively high sulfur
coals in eastern or midwestern locations. However, there are signifi-
cant differences in the bases and assumptions for the estimates which
make direct comparison of costs from different studies difficult. The
most important of these are as follows:
• Battery limits vary from waste disposal facilities only to
complete systems including all waste processing starting at
the scrubber discharge.
• In most cases, capital and operating costs are presented on
a lump sum basis for the entire system rather than broken down
into modular units.
• Wide variations in plant load factors (from 48.5% to 80%)
skew costs to the high side for the low load cases.
• Design assumptions relative to waste physical properties and
the depth of wastes in ponds and landfills vary significantly.
This can affect land requirements and disposal costs by 30%
or more.
• The assumptions regarding incorporation of fly ash in the dis-
posal of FGD where fly ash is separately collected vary in
different studies.
6-9
-------
• Different approaches have been used for incorporating land costs
in the disposal estimates. In some cases, the cost of land is
included in depreciable capital.
• The handling of site monitoring and land reclamation usually
differ markedly in generalized cost studies; however, for the
most part those considered here do not include these costs.
The effect of these differences in system design and operating
assumptions can create a wide range of disposal costs for any given mode
of disposal. Direct comparisons of costs from different studies, there-
fore, requires a complete understanding of the bases upon which the costs
were prepared.
The problem of handling land costs for dry impoundment and wet ponding
systems can be difficult. Consideration must be given to the type of
disposal operation and the potential land use following retirement of the
disposal area as well as the purchased price of the land. In some cases,
it may be appropriate to include land costs as a part of depreciable
capital, particularly for wet ponding of unstabilized wastes. On the other
hand, land values may actually appreciate for some dry impoundment areas,
depending upon locale, type of wastes impounded, and the manner of final
reclamation.
Wet Ponding
The two most comprehensive studies of the cost of wet ponding of
FGC wastes have been performed by TVA and Aerospace. In the TVA study
a total of 68 different cases for stabilized and unstabilized wastes
were evaluated covering variations in plant size and age, coal composi-
tion, waste processing, scrubber operation, distance to disposal sites,
and pond lining requirements. Table 6.3 summarizes the capital and
operating cost estimates for the 25 cases representing waste disposal
systems on new boilers equipped with conventional direct limestone
scrubbing for combined particulate and SC>2 removal. The base case for
these costs involves direct discharge of scrubber slurry to an onsite
clay-lined pond (1 mile from the plant). For onsite disposal of unstabilized
wastes TVA's estimates of capital costs range from $24.3/kW to $49.0/kW
with corresponding annual operating costs oj. :5.55/dry ton to $12.12/dry
6-10
-------
Table 6.3
Summary of TVA Cost Estimates for Wet Ponding
Basis: 1979/1980 Costs
500-MW New Boiler
3.51 Sulfur, 16* Ash
Conventional Limestone Scrubbing
Simultaneous SO, and Fartlculate Removal
Scrubber Discharge Directly to Fond
FGD Scrubber Costs - Capital - $72.74/kWh
- Operating • 3.38 milla/kWh
Operating Costs
Capital Costs ($/kW) Operating Costs (mills/kWh)c ($/dry ton)c
UnstabllUed Stabilized
Variation Comparisons
Plant Size (Mew)
ZOO MW
| 500 MJT[
1500 MW
Sulfur Content
2.01
| 3.5Z |
5.0X
Pumping Distance
| 1 mile"]
5 mile
10 mile
Thickening (35X Solida)
1 mile
5 mile
10 mile
Land Availability
Optimal Cv20-ft depth)
75Z of Optimal
301 of Optimal
Settled Density
40Z Solids
SOZ Solids |
60Z Solids
Lining Requirement
Unllned
| Clay Lined |
unstabillaed
49.0
34.4
24.3
26.8
34.4
41.3
34.4
53.7
74.8
37.0
49.8
62.9
34.4
36.0
45.4
40.1
34.4
30.4
28.8
34.4
Synthetic Lined ($2.50/yd*) 46.1
Synthetic Lined ($4.SO/yd2) 33.4
Stabilized Uastabilized
69.7 1.44
48.2 0.94
32.2 0.64
38.5 0.75
48.2 0.94
57.0 1.10
48.2 0.94
62.0 1.58
75.5 2.14
1.06
1.48
1.84
48.2 0.94
62.1 0.96
75.4 1.18
1.07
0.94
0.84
0.79
0.94
1.21
1.40
Stabilized
2.60
1.91
1.36
1.52
1.91
2.29
1.91
2.32
2.67
1.91
2.25
2.60
-—
8 1 1 represents base conditions.
12.12
8.08
5.55
9.37
8.08
7.35
8.08
13.61
18.48
9.10
12.79
15.89
8.08
8.29
10.15
11.54
8.08
6.05
6.81
8.08
10.47
12.07
20.41
15.32
10.87
17.45
15.32
14.08
15.32
18.57
21.39
15.32
18.06
20.82
b Stabilized via Draw's Synearth ptoceat using 7Z Calcilox*
°Baaed upon 7,000 hra/yr operation at full load.
6-11
-------
ton. As would be expected, the most important factors for onsite disposal
are those affecting the pond size and construction requirements—e.g.,
quantity of wastes (sulfur content and plant size), type of lining, and
solids settling properties. For example, ponding costs appear to vary
to about the 0.65 capacity factor for plants in the size range of 500 to
1500 MW. For offsite disposal the cost of slurry pumping becomes signi-
ficant; for distances greater than about two miles, thickening of the
wastes prior to disposal is generally cost-effective.
The cost of wet ponding of stabilized wastes estimated by TVA is
significantly more than that of unstabilized wastes unless lining require-
ments become excessive. The basis for these stabilization costs is Dravo's
® ® /i
Synearth process using Calcilox as the additive. The cost of the Calcilox
is a significant factor in the overall costs. At the 7% addition rate
assumed here (on total dry weight basis) the cost of the Calcilox
accounts for 15-30% of the total annual operating costs.
Analogous costs for wet ponding of unstabilized wastes have been
prepared by Aerospace. The basis and assumptions for these costs are
generally similar to those of a number of cases considered by TVA. In
1978 Aerospace [113] published estimates of disposal costs for wet pond-
ing ash and FGD wastes from model direct limestone scrubbing systems on
1000-MW and 500-MW boilers firing high sulfur coal. The annual average
cost for codisposal of thickened wastes in a clay-lined pond, at a dis-
tance of one mile, were estimated to be $4.89/dry ton and $6.07/dry ton
for 1000-MW and 500-KW systems, respectively. For disposal in a PVC-lined
pond (20-mil thickness) annual costs were estimated to be $7.25/dry ton
and $9.01/dry ton for the 1000-MW and 5.00-MW cases, respectively. At
first inspection, these costs appear reasonably close to those estimated
by TVA (see Table 6.3); however, there are important differences which
must be reconciled before a direct comparison can be made. Table 6.4
compares the basis for the Aerospace and TVA estimates for the 500-MW
cases. The most important differences affecting the cost estimates are
as follows:
• Base Year - Aerospace's costs are based in mid-1977 dollars,
while TVA's costs were prepared in mid-1980 dollars.
6-12
-------
Table 6.4
Comparison of Generalized Costs for Wet Ponding Unstabilized FGC Wastes
Basis: Plant Size
FGC System
- 500 MW
- Conventional Limestone Scrubbing for
S02 and Particulate On-Site, Clay-Lined
Ponds
Battery Limits - Thickener Underflow
Design and Operating Assumptions
Coal Properties = % S
% Ash
S02 Removal Efficiency (%)
Limestone Utilization (%)
Annual Operating Hours—30-yr. Avg.
Annual Waste Production—30-yr. Avg.
(dry tons)
Waste Transport: Distance (miles)
Pipeline Location
Pond Construction: Site Preparation
Lining Depth (inches)
Waste Depth (feet)
Pond Land Requirement (acres)
Capital Cost Factors
Base Year
Indirect Costs Included Fixed Investment
Engineering and Fees
Field Expense
Contingency
Other Indirect Costs in Total Capital
Interest During Construction
Startup Allowance
Land
Aerospace
3.5
14
90
80
4380
Surface
Minimal
18
30
~310
mid 1977
Not Included
$5000/acre
TVA
3.1
16
78.7
67
4250
246,500
1
Underground
Minimal
12
21 and ~28
407 and 305
mid 1980
Varies with Alternative ~20%
of Direct Costs
"20% of (Direct + Eng. + Fees + Expenses)
12% of Fixed Plant
10% of (Fixed Plant Less Pond Const.)
$3500/acre
-------
• Handling of Land Costs - Aerospace's cost estimates include
land at $5,000/acre as a part of total depreciable capital,
while land costs are not depreciated in TVA's estimates.
• Pond Design - Aerospace's costs are based upon a 30-foot deep
pond with and 18-inch clay liner, while TVA's costs are for
20-foot deep ponds (except for the variations on optimal space
which include a 30-foot deep alternative) with a 12-inch clay
liner.
• Waste Quantity - While the annual average waste quanitites of
total ash and FGD wastes over the life of the plant are
roughly 356,000 tons in both studies, the waste quantities used
in the dollars/ton estimates differ—Aerospace's costs are based
upon the 30-year average while TVA's costs are based upon the
annual average for the first ten years of operation (for the
costs shown in Table 6.3).
• Processing Equipment - TVA's estimates include the waste dewater-
ing equipment (thickener, surge tank, and associated pumps and
piping) as well as the pipeline and pond, while Aerospace's costs
include only the pipeline and pond.
• Pipeline - Aerospace's costs are based upon pipeline built above
ground while TVA has assumed an underground line.
• Indirect Capital Costs - TVA's estimates include all engineering,
owner's expenses and contingency while Aerospace's estimate
include no engineering or owner's expenses.
In order to provide a better comparison of the Aerospace and TVA
costs, an attempt has been made to adjust the estimates for the 500-MW,
clay-lined pond case by putting them on a reasonably consistent basis.
Specifically, five adjustments have been made:
• Conversion of costs to 1978 dollars using an escalation factor
of 8% over the period 1977 through 1980;
• Reduction in the load factor for TVA's annual costs shown in
Table 6.2 from 80% to the annual 30-year average of 48%, there-
by reducing the quantity of solids handled and some direct
operating costs (principally power);
6-14
-------
• Extraction of land costs from the Aerospace depreciable capital;
• Extraction of the dewatering equipment and all associated
indirect costs from TVA's depreciable capital; and
• Inclusion of engineering, interest during construction,
and starting in Aerospace's depreciable capital by increasing
the existing capital (excluding land) by 25%.
These adjusted capital investment anu operating costs resulting
from these modifications are as follows:
TVA Aerospace
Total Capital Investment ($/kW) 28 20
Annual Average Operating Cost
($/dry ton) 11.00 6.50
On this adjusted basis, the capital and operating costs differ
significantly. The biggest part of the difference in operating costs
is due to the variation in capital costs.
It is interesting to compare these cost estimates with the estimate
prepared by NUS for disposing of fly ash alone in an unlined pond. For
an annual production rate of 262,800 tons of ash per year (compared with
TVA's 246,500 tons per year annual average), NUS estimated about $16.50
per ton in 1978 dollars (converted from 1979 @ 8% per year).
Dry Disposal
In TVA's economic study of FGC waste disposal, four different types
of wastes from direct lime and limestone scrubbing systems have been
evaluated for dry impoundment: unstabilized wastes from simultaneous S0?
and particulate removal; wastes from S02 removal blended with fly ash; sta-
bilized wastes; and gypsum wastes from forced oxidation. Of these, only
the last three can be considered to be realistic options for dry impound-
ment. Unstabilized wastes from conventional direct lime or limestone
scrubbing systems are not easily dewatered to the point where they can
be handled, placed, and compacted as a stable fill material.
Table 6.5 shows cost estimates prepared by TVA for the processing
and disposal of ash blended wastes, stabilized wastes, and gypsum produced
by forced oxidation. Since each of these involves a different type of
6-15
-------
Table 6.5
Summary of TVA Estimates for Dry Impoundment Disposal Systems
Basis: Limestone Scrubbing
500-t* K«v Botl.r
3.5! S Coal, 16Z Ash
variation
Comparisons*
FCC SYSTEM (300MO
DISPOSAL SYSTEMS
Sulfur Content6
2.01
5. OX
Disposal Distance
|l mile!
5 mile
10 mile
Additive Feed
3 wtZ
| 4 wtt"]
5 wtZ
Ash Blendlngb
92.0
14.7
17.2
19.1
17.2
17.9
18.7
—
—
—
Stabilisation
72.7
18.7
21.4
23.9
21.4
22.8
23.8
20.6
21.4
21.5
Gypsum*1
77.3
9.6
10.8
11.8
10.8
11.5
12.0
—
—
—
Ash Blending
3.94
0.91
1.07
1.20
1.07
1.25
1.39
—
—
—
Stabilization
3.38
1.33
1.51
1.77
1.51
1.85
2.14
1.43
1.51
1.57
Gypsum
3.67
0.77
0.89
0.93
0.89
1.06
1.22
—
—
—
Ash Blending
—
11.26
9.20
7.88
9.20
10.81
11.96
—
—
—
Stabilisation
15.57
12.55
11.29
12.55
15.40
17.73
11.96
12.55
12.95
Cypsm
9.74
7.86
6.43
7.86
9.37
10.80
—
—
—
* I I Indicates base CAM condition.
FCC system for ash binding includes high efficiency electrostatic preclpitator.
treatment Involves lime addition to nixed ash and FGD vastes.
Limestone forced oxidation system for simultaneous SOj and partlculate control-
Slight adjustments In FGD costs are required to account for changes in inlet S<>2 and S<>2.
removal efficiency.
-------
scrubber operation, the costs for waste processing and disposal cannot
be evaluated out of the context of the entire FGC system. Hence, TVA
cost estimates for the particulate control and SCL scrubbing systems are
also shown in Table 6.5. For the ash blending option, the cost shown for
the FGC system, $92/kW, includes an electrostatic precipitator for dry ash
collection. For the stabilization option, the FGC system involves simul-
taneous S02 and particulate control; consequently, the cost for gas scrubbing
is considerably lower, $72.7/kW. The FGC system for producing gypsum also
involves simultaneous SC>2 and particulate control; however, the additional
cost of forced oxidation of the scrubbing liquor increases the capital
investment to $77.3/kW. According to these estimates, the base case
annual costs for these three options (@ 3.5% sulfur) rank as follows:
Forced oxidation (gypsum) - 4.56 mills/kWh
Stabilization via lime addition - 4.89 mills/kWh
Ash blending - 5.01 mills/kWh
The relative rankings are a result of the assumptions regarding particulate
control requirements and the superior dewatering properties of gypsum.
Inclusion of electrostatic precipitators for all cases would, of course,
change these rankings. It is also possible that dry ash collection and
blending would be required for wastes from conventional direct scrubbing
systems in high sulfur coal applications.
In a study of stabilization technology for EPRI, Michael Baker Associates
compared costs for conceptualized dry impoundment disposal systems for ash
blending versus stabilization. The basis for these estimates was a 1000-MW
power plant (two 500-MW boilers) firing 3.5% sulfur, 15% ash coal, and
equipped with a high efficiency electrostatic precipitator followed by a
conventional lime scrubbing system. Based upon vendor quotations for
turnkey waste processing facilities, estimated capital costs were $8.8/kW
for ash blending and $9.0/kW for stabilization. Corresponding first-year
annual revenue requirements were $6.90/dry ton of total wastes for ash
blending and $7.70/dry ton for stabilization; the difference being almost
entirely due to the cost of lime. Stabilization costs were based upon lime
addition at a rate equivalent to 2% of the dry weight of FGD wastes and
6-17
-------
fly ash. Increasing lime addition by 1% would increase annual revenue
requirements for stabilization by about $0.50/dry ton of total wastes.
At a 3% addition rate, then, the cost of treatment would run about 20%
higher than ash blending alone.
This differential is slightly lower than other estimates reported in
the literature. Research Cottrell, Inc., for example, estimates the
cost of treatment of wastes from a 500-MW plant firing 3% sulfur coal
to be 30-35% higher than ash blending [114].
Mine Disposal
Estimates of mine disposal costs have been prepared for conceptualized
systems by Arthur D. Little, Inc., as a part of its feasibility study for
EPA [29]. Both surface mine and underground mine options were considered.
Table 6.6 summarizes the cost estimates for the most promising of the
options evaluated.
The costs were prepared for wastes from a 500-MW boiler firing 3%
sulfur, 10% ash coal equipped with a high efficiency electrostatic pre-
cipitator followed by a conventional lime scrubbing system. The wastes
were assumed to be filtered and treated or simply blended with ash to
produce a material that could be easily handled and transported. The
cost of the disposal systems shown in Table 6.7, though, does not include
any waste processing. The battery limits begin at the tail end of the
processing facility and include: waste transfer, storage, and loading
at the plant; transport to the mine; and unloading, storage/transport,
and placement at the mine. Two cases are shown for surface mine disposal;
one for onsite disposal (mine-mouth power plant), and one for offsite
disposal (200-mile rail haul). In both cases, wastes are dumped in the
mined-out pit prior to overburden replacement. Dedicated trucks were
assumed for hauling and placement; for rail haul, a charge of lc/ton-mile
for use of the coal train returning to the mine. For underground mine
disposal, only onsite disposal is shown. Thickened sludge (treated or
untreated) would be piped to the mine area and pumped down through bore-
holes into open rooms partitioned from the active mining areas with
bulkheads.
The costs for onsite (mine-mouth disposal) are estimated to be
$3.00-3.50/dry ton, and $6.50/dry ton for offsite disposal in a surface
6-18
-------
Table 6.6
Summary of Mine Disposal of FGC Wastes
Basis: 500-MW Plant
3% Sulfur, 10% Ash Coal
Annual Load Factor - 80%
90% S02 Control
1977 Dollars
Capital Cost
Mine Type
Surface (Truck Dump)
Location
Onsite
Offsite
Transport
Truck
Rail
($/kW)
3.7
3.9
Operating Costs
(mills/kWh)
0.35
0.70£
($/dry ton)
3.30
6.50
Underground (Hydraulic Fill)
Onsite
Pipeline
2.1
0.35
3.20
1Rail haul costs assumed to be $2.00/short (wet) ton = lc/ton-mile.
Source: [29]
-------
Table 6.7
Summary of Preliminary Cost Estimates for Ocean Disposal of FGC Wastes
(Concentrated Bottom-Dump Disposal)
Operating Costs
1
ro
G>
Ocean Locale
Contentintal Shelf
(25 nmi)
Deep Ocean
(100 nmi)
Waste Type3
Soil-likeb
Block-like
Soil-like0
Block-like
i.ai>-L(.a.L (..OBI.
($/kW)
3.2-3.7
6.9-7.4
5.3-7.25
(mills /kWh)
0.4-0.5
0.6-0.7
0.65-0.85
0.85-1.05
($/dry ton)
4.15-4.90
6.35-7.10
6.85-8.90
9.05-11.10
Soil-like: Mixed fly ash and FGD waste or stabilized FGD wastes.
Block-like: Stabilized waste (assumed to be reclaimed from curing ponds)
Not considered promising at this time.
May only be promising for sulfate-rich wastes.
Source: [29]
-------
mine. The difference is principally due to the cost of rail haul and
the additional storage/transfer requirements for an offsite mine.
As in the case of wet ponding, an attempt was made to compare these
cost estimates with those prepared by TVA for dry impoundment by adjust-
ing the assumptions to a consistent basis. This principally involved
converting the costs to a constant 1978 dollar basis and deleting
waste processing facilities and costs from the TVA estimates. The
adjusted mine disposal costs of roughly $3.50/dry ton compared quite closely
with the adjusted TVA estimates of $3.50-4.00/dry ton for impoundment of
ash blended and stabilized waste. It would be expected that mine disposal
would be less expensive than impoundment since in most cases compaction
would not be required nor would additional land costs or land reclama-
tion be required.
TVA, as a part of its ongoing evaluation of FGC wastes disposal
costs for the EPA, is now preparing generalized cost estimates for sur-
face mine disposal for comparison with other dry impoundment options.
6.2.2.2 Ocean Disposal Costs
Ocean disposal is still in the research stage. Costs for such
operations will be highly dependent on the type of wastes which can be
discharged, if any, and the measures required to mitigate or avoid
potential environmental impacts.
Based upon a preliminary feasibility study performed by Arthur D.
Little, Inc. [29], costs were prepared for conceptualized systems
representing likely disposal options. Table 6.7 summarizes the cost
estimates for both deep ocean (100 nautical miles offshore) and shallow
ocean (25 nautical miles offshore on the continental shelf) disposal on
the East Coast. The ranges of costs shown cover the use of tug/barge
combinations and self-propelled ships. For near-shore disposal, self-
propelled ships are slightly less expensive than tug/barge systems
(assuming a 25-nmi one-way distance), but self-propelled ships are con-
siderably cheaper than tug/barge combinations for deep ocean disposal.
As in the case of the mine disposal systems, the costs shown in Table 6.7
do not include any waste processing costs; however, the costs of recovering
stabilized wastes from 30-day curing ponds (to obtain a brick-like material)
are included.
6-21
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It is apparent from these preliminary cost estimates that if stabil-
ization is required for any type of ocean disposal, then the costs of
deep ocean disposal may be prohibitive because of the transport distances
involved. The disposal of wastes on the continental shelf, on the other
hand, may be cheaper than returning wastes to an offsite mine.
Cost estimates for ocean disposal are now being updated by Arthur D.
Little, Inc. for the most promising options. The State University of
New York at Stoney Brook is also now conducting a study of reef construc-
tion using stabilized blocks of FGC wastes under joint industry/government
funding. Additional cost data on ocean disposal are expected to result
from this work.
6.3 Economic (Cost) Impact Studies
Two general economic (cost) impact analyses of FGD waste disposal
regulations on the utility industry have been undertaken to date. One has
been performed by Radian for EPA's Industrial Environmental Research Labora-
tory [111] and the other has been performed by SCS Engineers for EPA's Municipal
Environmental Research Laboratory [112]. Although final reports are not
available for either study, preliminary results have been issued in
draft form. Because of differences in the purpose, scope, and bases
for these two studies, the results are not expected to be directly
comparable; however, they should give a first approximation of the effects
of pending or potential future waste disposal regulations on the incre-
mental cost of FGC waste disposal to the utility industry.
6.3.1 Radian Study
The Radian study focuses on the economic impact of RCRA under the
conditions that FGC wastes (both ash and FGD wastes) are considered non-
hazardous [111]. The economic evaluation is based on hypothetical enforce-
ment scenarios using a model plant approach involving "typical" 1000-MW
coal-fired plants. Eight different disposal methods for fly ash, FGD wastes,
and combined FGC wastes were selected as representative of existing and
future disposal practices through 1985. These are:
• Fly ash - ponding and dry landfill,
6-22
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• Ash-free FGD waste - ponding of thickened or unthickened
slurries and landfill of dewatered waste., and
• Combined FGC waste - ponding of thickened or unthickened
slurries and landfill of dewatered waste.
Ponding or dry fill of stabilized material was not considered.
Cost estimates were then prepared for each of these options for the
model plant and cost factors developed to pply these costs to the entire
generating capacity assumed to be affected.
The potential impact of RCRA on existing plants was assumed to be
limited to those beginning operation after 1970. It was assumed that
one-half of the existing capacity starting up after 1976 would have to
move their disposal sites from a current average of about 5 kilometers
from the plant to about 16 kilometers (the basis for this assumption is
not provided), and that all would use lined ponds or unlined dry fills.
For new plants, it again was assumed that all disposal areas would be
either lined ponds or unlined dry fills, and that all plants would have
to increase the average distance to disposal sites from the usual 5 kilo-
meters to about 8 kilometers in order to protect groundwaters (a shorter
distance than for existing plants because increased concern in siting
disposal areas would lead to better selections for newer plants). The
major effects of RCRA then would be increased distances to disposal sites
and the use of lined ponds and dry fills. (No linings are assumed to be
required for dry fills because it is assumed that all new fills would be
located in impermeable areas or areas where groundwater quality would not
be in danger.)
Based upon these assumptions, it is estimated that the increase in
capital investment for waste disposal due to compliance with RCRA will
amount to approximately one billion dollars, or about 36%, through 1985
(in 1979 dollars). However, required annual revenue requirements (in
1979 dollars) would increase only about 5-6% or about 70 million dollars
per year. Table 6.8 summarizes these cost estimates. It should be noted
that these estimates do not include: sunk costs associated with moving
existing disposal sites; costs for recovering wastes or reclaiming exist-
ing sites due to unacceptable groundwater contamination (or danger of it);
or costs for levees to protect against pond flooding.
6-23
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Table 6.8
Summary of Estimated Cost of Compliance
(Mid-1979 Dollars)
ON
I
Existing
Plants*
(1970-1978
Construction)
Planned and
Future
Facilities
(1978-1985)
Total Costs
Net Costs
Capital Investment Costs ($)
Estimated Cost Estimated Current
of Compliance with Predicted
with RCRA Cost - No RCRA
49,075,000
0
3,631,750,000
2,699,650,000
3,680,825,000 - 2,699,650,000
981,175,000
Revenue Requirements ($/yr)
Estimated Cost Estimated Current
of Compliance or Predicted Cost
with RCRA No RCRA
68,725,000
55,350,000
1,202,700,000 - 1,148,140,000
1,271,425,000 - 1,203,490,000
67,935,000
Assuming 50% out of compliance
Source: [111]
-------
6.3.2 SCS Study
SCS Engineers has evaluated the impact of different degrees of severity
of FGD waste disposal regulations on the utility industry [112]. In contrast
to the Radian study, the SCS analysis does hot specifically address RCRA
nor does it include fly ash except where it is co-disposed with FGD wastes.
Five regulatory scenarios were considered in the SCS analysis, as
follows:
1. Federal Advisory - State Legislation and Enforcement—
Simple permitting, stabilization not required and not
commonly used (no change from current trend in disposal
practices).
2. Federal Advisory - State Legislation and Enforcement—
Site-specific evaluation with stabilization sometimes
required (no urban ponding).
3. General Federal Legislation - State Enforcement—Physi-
cal stabilization required, no ponding.
4. Comprehensive Federal Legislation - State Enforcement
upon Approval—Chemical stabilization required in urban
areas.
5. Comprehensive Federal Legislation and Enforcement - No
State Involvement—Chemical stabilization universally
required, specifications given for the stabilization
techniques.
These five regulatory scenarios were then applied to a set of 10
model plants covering three geographical regions, three coal types, and
urban and rural locations. Six disposal methods were considered: unstab-
ilized wastes in unlined ponds; unstabilized wastes in clay-lined ponds;
stabilized wastes (Dravo) in unlined ponds; dry landfill of dewatered,
unstabilized wastes; dry landfill of dewatered, unstabillzed wastes mixed
with ash; and dry landfill of stabilized wastes (IUCS). Capital and
operating costs and annual revenue requirements were then perpared for each
model plant and disposal option based upon the generalized disposal cost
6-25
-------
estimates prepared by TVA (see Section 6.2), and these were applied to
1980 and 1985 projections of FGD capacity categorized according to the
ten model plants.
Table 6.9 summarizes the expected average future cost (in 1980 dol-
lars) for FGD waste disposal under each of the regulatory requirements
(scenario No. 1), FGD waste disposal is expected to cost an average of
1.02 mills/kWh for capacity on line in 1980 and 0.76 mills/kWh for the
total capacity on line in 1985; these correspond to projected annual reve-
nue requirements for the on-line capacity of about $2.6 billion and $3.1
billion respectively. Increasingly more stringent regulations are expected
to add from 0.007 mills/kWh (scenario No. 1) to 0.37 mills/kWh (scenario
No. 5) in 1980; and from 0.008 mills/kWh (scenario No. 1) to 0.56 mills/
kWh (scenario No. 5). These costs do not include the sunk cost of capi-
tal investments already made under scenario No. 1 but which are no longer
useable under the more stringent regulations.
6.4 Economic Uncertainties
There are a number of uncertainties concerning FGC waste disposal
that importantly affect overall disposal economics and viability of
certain disposal modes. Important among these are uncertainties relat-
ing to land use/availability/cost, long-term maintenance of retired dis-
posal sites, and the financial liability/responsibility of disposal sites.
These are not data gaps in the sense that they can be readily resolved
through current studies or R&D efforts; rather, they are social/technical/
economic issues which will require continuing consideration and evaluation.
The issue of land use, availability, and cost can be relatively complex
and will become more important with the growing implementation of nonrecovery
FGC systems. One aspect of this issue is directly related to regulations—
i.e., the availability of land that meets all the environmental constraints
of federal and state laws, and, in particular, RCRA. This can affect not
only plant siting and/or disposal distances but also the type of FGC system
employed and the mode of waste disposal. There are also many facets to
this issue which fall outside the realm of regulations but which can
directly affect FGC waste disposal economics. These generally fall under
the category of land-use planning and resource allocation, which impact
6-26
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Table 6.9
Summary of Regulatory Impacts to Consumers in Mills/kWh*
I
ro
Location/
Coal Type
Setting
Regulatory
Scenario No.
1
2
3
4
5
Regulatory
Scenario No.
1
2
3
4
5
Western
Urban
Rural
Midwestern No. 1
Urban
Rural
Midwestern No.' 2
Urban
Rural
Eastern No. 1
Urban
Rural
Eastern No. 2
Urban
Rural
Industry
Average
Percent
Increase
Over
Scenario
No. 1
For the Year 1980:
.53
.80
.80
1.00
1.00
.61
.61
.72
.72
1.00
.88
1.08
1.08
1.44
1.44
.93
.93
1.10
1.10
1.44
1.28
1.28
1.28
1.83
1.83
1.30
1.30
1.49
1.49
1.81
1.20
1.20
1.20
1.20
1.20
.57
.57
.88
.88
1.19
1.59
1.59
1.59
1.59
1.59
1.59
1.59
1.59
1.59
1.59
1.017
1.024
1.136
1.190
1.400
0.7
11.7
17.1
37.7
For the Year 1985:
.53
.80
.80
1.00
1.00
.55
.55
.64
.64
1.00
.91
1.08
1.08
1.44
1.44
.67
.67
1.08
1.08
1.44
1.28
1.28
1.28
1.83
1.83
1.07
J.07
1.42
1.42
1.81
.78
.96
.96
1.20
1.20
.57
.57
.88
.88
1.19
1.59
1.59
1.59
1.59
1.59
1.59
1.59
1.59
1.59
1.59
.759
.767
.981
1. 026
1. 321
1.)
29.7
35.2
74.2
•All amounts are in present value as of mid-1980.
Source: [112]
-------
land valuation and may ultimately constrain the types of wastes disposed
of and the manner of disposal. While land-use planning frequently may
be a local issue or even site-specific, long-term regional implications
of large-scale FGC waste disposal can also be important. In this regard,
the most cost-effective disposal system based upon the economics of the
type of FGC system and the construction of the associated waste process-
ing and disposal facilities may not be the most desirable approach in
terms of long-term land use and availability.
Long-term maintenance of retired disposal sites is related to land
use and availability. The need and costs for long-term maintenance or*
ultimate reclamation of a site cannot be determined based upon current
knowledge. It therefore remains an economic uncertainty, but one which
must be given increasing consideration as more disposal systems are
initiated and more information becomes available on existing sites.
An issue associated in many respects with long-term maintenance of
disposal sites is that of financial liability/responsibility for both
the disposal site itself and any environmental impacts resulting from
the disposal operation. This is both a legal and economic question,
and includes such aspects as:
• Whether a contractor for waste processing and/or disposal
can assume the overall responsibility and liability of the
utility;
• What the extent of liability is for not complying with
regulations or for causing impacts (sociological as well
as environmental) that are not within the regulatory
coverage; and
• The availability, extent of coverage and cost of
insurance to cover the financial liability of the
utility or contractor.
Some of these questions are now being addressed, but a clear-cut
resolution will be many years away, if at all.
6-28
-------
6.5 Data Gaps
Current data gaps related to the economics of the disposal of FGC
wastes include both cost information per se, as well as waste properties
and disposal requirements that directly impact disposal costs. In this
regard, data gaps refer to areas which could be currently addressed by
government and/or industry initiatives. The most important of these are
listed below.
• There is a general lack of reliable cost information from
commercial operations of most types of FGC disposal. On-
going and planned EPA demonstration projects should at
least partially fill this gap.
• There have been no definitive studies on the disposal of
wastes from dry sorbent systems and the associated costs.
• Existing physical and engineering properties data on some
types of wastes are not adequate as a basis for developing
design requirements needed for reliable estimates of cost-
effective disposal systems. Examples include: the dis-
posal of gypsum untreated in dry impoundments; the amount
of ash and lime required for adequate stabilization of
some sulfite-rich wastes; and the potential for use of
well-stabilized materials as liners for dry impoundments
of ash blended wastes.
6-29
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R-5
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November 21, 1977.
R-6
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74. Hydraulic Disposal to Mines, prepared by Nelson R. Tonet, Duquesne
Light. Presented at ASME-IEEE Joint Power Generation Conference,
Pittsburgh, September 27 - October 1, 1970.
75. "Study of the Use of Lime/Limestone Flue Gas Desulfurization Sludge
in Underground Mines Subsidence Prevention", Work by Radian Corporation
for the U. S. Bureau of Mines, Department of Interior, Washington,
D. C., 1975.
76. "Feasibility Study Underground Coal Mine Drainage Abatement and
Subsistence Control Using FGD Wastes", W. A. Duvel, D. W. Hupe,
D. A. Palomer, and R. J. McLaren, Michael Baker, Inc. Report to
EPA-IERL, Cincinnati, Ohio 45268, Draft Report, May 1978.
77. "Surface Coal Mining and Reclamation Operations, Proposed Rules for
Permanent Regulatory Programs," Federal Register, Vol. 43, No. 181,
September 18, 1978, p. 41661-41940.
77. "Surface Coal Mining and Reclamation Operations, Proposed Rules for
Permanent REgulatory Programs," Federal Register, Vol. 43, No. 181,
September 18, 1978, p. 41661-41940.
78. Ibid., p. 41887 (Part 816.52) and p. 41907 (Part 816,52).
79. Ibid., p. 41751, p. 41843 (Part 780.21), p. 41894 (Part 816.95).
80. Hazardous Waste Guidelines and Regulations," Federal Register,
Vol 43, No. 243, December 18, 1978, p. 58945-59022.
81. Ibid. p. 59015 (Part 250.46-2), pp. 58991-2.
82. Ibid, p. 58956 (Part 250.13 [d]).
83. Ibid, p. 59000 (Part 250.43 [f,h]).
84. Ibid, p. 59004-6 (Part 250.43.7, .43-8).
85. Ocean Dumping, Parts 227 and 228, Federal Register, Vol. 42, No. 7, 1977.
86. Ibid, p. 2477-8 (Part 227.5).
87. Ibid, p. 2466.
88. Ibid, pp. 2487-9 (Part 228.13).
89. "Proposed Methods for Leaching of Waste Materials", American
Society for Testing and Materials, Philadelphia, PA, Committee D-19,
May 1978.
90. Lowenbach, William, "Compilation and Evaluation of Leaching Test
Methods," U.S. Environmental Protection Agency Report EPA-600/2-780-095,
May 1978.
R-7
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91. Fenn, D., E. Cocozza, J. Isbister, 0. Braids, B. Yare, P. Roux and
B. Vincent, "Procedures Manual for Ground Water Monitoring at Solid
Waste Disposal Facilities," U.S. Environmental Protection Agency
Report, EPA-530/SW-611, August 1978.
92. "Manual of Methods for Chemical Analysis of Water and Wastes," U.S.
Environmental Protection Agency Report EPA-625-16-74-003, 1974.
93. "Standard Methods for the Examination of Water and Wastewater,"
American Public Health Service, Washington, DC, 13th Edition, 1971.
94. Gibb, T. R. P., (ed), "Analytical Methods in Oceanography," American
Chemical Society, Advances in Chemistry Series 147, (1975).
95. Chemical Week, December 6, 1978.
96. ASTM D19.12, Draft Proposed Standard Protocol for Acute Fish Toxicity
Bioassay and Draft Proposed Salmonella/Mammalian-Minosome Mutagenesis
Assay for Complex Environmental Mixtures, presented at meeting of
D19.12, American Society for Testing & Materials, Philadelphia, PA,
October 24, 1978.
97. Personal Communication, Florida Department of Environmental Regulation
to Sarah Bysshe, Arthur D. Little, Inc. 1978.
98. Morgan, G. B., "Energy Resource Development: The Monitoring
Components," Environmental Sci. Tech. 12, 34-43 (1978).
99. Miller, S., "Federal Environmental Monitoring: Will the Bubble
Burst?" Environmental Sci. Tech. 12^,1264-1269 (1978).
100. Frascino, P. J. and Vail, D. L. "Utility Ash Disposal - State of the
Art" Proceedings of the IV Ash Utilization Symposium, St. Louis,
Mo., March 24-25, 1976.
101. "A Procedure for Evaluation of Environmental Impact," Leopold, L. B.,
et al. Circular 645, U.S. Geological Survey, Washington, D.C., 1971.
102. Barrier, J. W., "Comparative Economics of FGD Waste Disposal," EPA
Industry Briefing Conference, August 1978.
103. Barrier, J. W., H. L. Faucett, and L. J. Benson, "Economics of FGD
Waste Disposal," U.S. Environmental Protection Agency Report, EPA-
600/7-78-058a, March 1978.
104. Barrier, J. W., "Economics for Auburn Study of Sludge Dewatering
Equipment," A Report to H. L. Faucett, TVA, September 1978.
105. Rossoff, J. and R. C. Rossi, "Disposal of By-Products fron Non-
Regenerable Flue Gas Desulfurization Systems: Initial Report,"
U. S. Environmental Protection Agency Report, EPA-650/2-74/037a,
May, 1974.
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106. Rossoff, J. and R. C. Rossi, "Flue Gas Cltaring Waste Disposal EPA
Shawnee Field Evaluation," presented at the EPA Flue Gas Desulfur-
ization Symposium, New Orleans, L.A. , March 1976.
107. Rossoff, J., et al., "Disposal of By-Products from Non-Regenerable
Flue Gas Desulfurization Systems: A Status Report," Presented at the
EPA Flue Gas Desulfurization Symposium, Atlanta, GA, November 1974.
108. Rossoff, J., et al, "Disposal of By-Prod-icts from Non-Regenerable
Flue Gas Desulfurization Systems: Seccnu Progress Report," U.S.
Environmental Protection Agency Report, EPA-600/7-77-052, May 1977.
109. Rossoff, J., et al, "Disposal of By-Products from Non-Regenerable
Flue Gas Desulfurization Systems: Final Report," U.S. Environmental
Protection Agency Report (Draft), March 1978.
110. Atwood, K. E. and Greenway, W. R. "Fly Ash Handling Systems
Study Relating to Steam Electric Power Generating Point Source
Category - Effluent Guidelines and Standards" prepared by C. W. Rice
Division of NUS Corporation to the Utility Water Act Group (UWAG)
July 1975.
111. Jones, B. F., et al, Radian Corporation, "Study of Non-Hazardous Wastes
from Coal-Fired Electric Utilities", DCN 200-187-41-08 Report to
EPA-IERL, Research Triangle Park, NC 27711, Draft Final Report,
December 15, 1979.
112. SCS Engineers "Economic Impact of Alternative Flue Gas Desulfurization
(FGD) Sludge Disposal Regulations in the Utility Industry" Report
to EPA Municipal Environmental Research Laboratories, Cincinnati,
Ohio. Draft Final Report, January 1979.
113. Leo, P. L. and J. Rossoff, Aerospace Corporation, "Controlling S09
Emissions from Coal-Fired Steam-Electric Generators: Solid Waste impact,"
Two Volumes, EPA Report No. EPA-600/7-78-044a and b. Environmental
Protection Agency, Washington, D. C., 20460, 1978.
114. Goodwin, R. W. and R. J. Gleason, "Options for Treating and Disposing
of Scrubber Sludge," Combustion. October 1978.
115 Epton, J. L. and Larimer, F. W., Interim Report on "Toxicity of
Leachates", ORNL, Oak Ridge, Tnn. Draft Report, January 21, 1979.
116. Personal Communication, John Munick, ASTM to C.J. Santhanam,
Arthur D. Little, Inc., February 1979.
117. Personal Communication, D. J. Hagerty, University of Louisville, to
C. J. Santhanam, Arthur D. Little, Inc., 1979.
R-9
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INDEX - VOLUME V
Acid-forming waste, regulatory control 3-65
Air-related impacts 2-95 to 2-97, 3-86 to 3-89, 4-27, 4-42
Aquifers, protection under RCRA 3-16
Backfilling under Surface Mining Control and Reclamation Act 3-77
Basins, waste disposal, control under RCRA 3-70
Bioaccumulation 5-12
Bioassay testing 5-11 to 5-13
Biological monitoring 5-9 to 5-14, 5-16, 5-18
Boiler derating under National Energy Act 3-90
Bottom Ash 2-4
physical properties, disposal practices 2-11 to 2-15, 4-20, 6-23
Cadmium concentration in waste, ocean dumping limitations 3-59
Calcium sulfate solubility 2-7 to 2-0, 4-14
The Clean Air Act 3-1, 3-86
Climate, effect on waste properties 2-53 to 2-54
Coal ash, effect on waste properties 2-1 to 2-4
Codisposal of ash and FGD waste 2-47, 4-45
Compaction, effect on waste properties 2-52, 2-109, 4-21 to 4-22
Consolidation, effect on eventual land use 2-82, 4-6 to 4-7, 4-22
Dam Inspection Act 3-67 to 3-68
Dewatered impoundments 2-88, 4-4, 4-43
Disposal facility, for FGD wastes 3-19, 6-8
Disposal of non-coal wastes 3-80
Disposal site size 4-8 to 4-10
Dravo stabilization process 2-31
EPA, effect on disposal practices 3-3 to 3-5, 3-72
Environmental impact 2-78 to 2-81, 4-1
Fly Ash
blending of 2-44 to 2-47, 2-92
disposal practices 2-9 to 2-11, 4-20, 6-22, 6-8
dry, disposal costs 6-8
physical properties 2-3
water contamination 2-94
wet disposal costs 6-8
FGC wastes
disposal economics 6-1, 6-10, 6-25
disposal field studies 2-20 to 2-21
disposal in surface mines 2-63 to 2-66, 2-89, 3-74 to 3-76
R-10
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FGC wastes (continued)
disposal in underground mines 2-68, 2-89
dust emissions from 3-86, 5-2
dry disposal of 2-42 to 2-43, 2-88, 4-20 to 4-27
erosion of 2-53, 2-96, 4-30
extract composition from 5-6 to 5-7
extraction procedure for 3-13, 3-18, 5-5 to 5-6
forced oxidation of 2-8, 4-43
grain properties of 4-3, 4-5
interim ponding of 2-43
leachates 4-14 to 4-17, 4-33 to 4-34, 4-40
leaching of 2-40, 4-12 to 4-13, 5-16
liquefaction of 2-83, 4-6
mechanical landfilling of 2-44
ocean disposal of 2-113, 2-72 to 2-77, 3-56 to 3-58
physical properties of 4-3
permanent impoundments for 3-77
permeability of 4-16. 4-18
pit-bottom disposal of 2-65
sludges 3-75 to 3-76, 4-3, 4-20
stability of 2-50, 4-11, 4-10 to 4-22, 5-15
treatment costs for 6-7
V-notch disposal of 2-65, 4-34
waste types 2-1
FGD
liquid wastes 2-8
nonrecovery systems 2-5
solid wastes 2-5 to 2-8
stability of 3-62, 3-78, 4-2, 4-13, 4-20, 4-28, 4-44
U.S. capacity of 1-1
waste disposal of 2-16 to 2-20, 6-23
Generating capacity, Coal-Fired Utilities 1-1
Ground water monitoring 3-17, 3-20, 3-36, 5-1, 5-7
Gypsum, production of 2-8
Gypsum stacking 2-35 to 2-37
Hazardous wastes
characteristics 3-18
management, under RCRA 3-11 to 3-12
standards, under RCRA 3-13 to 3-15, 5-2
under RCRA 3-11 to 3-13, 3-17 to 3-19
Hydraulic backfilling of mine tailings 2-69
Landfilling, design of 2-56 to 2-58, 3-24, 3-70
Land-related impact 2-82 to 2-85, 2-90, 4-42
Land costs for waste disposal 6-10
Land reclamation 3-22, 3-80, 4-23 to 4-25, 4-31 to 4-32
Land use for disposal 3-24, 3-69, 3-81, 6-9, 6-26
Land use planning in waste disposal 6-26 to 6-28
Leachate/soil interactions 4-16 to 4-17
R-ll
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Marine Protection Research and Sanctuaries Act of 1972 3-56
Mercury concentration, in wastes 3-59
Microbial oxidation 2-95
Mine drainage 3-32
Monitoring samples, from disposal sites 5-8, 5-18
National Energy Act 3-1, 3-90, 3-91
National Pollutant Discharge Elimination System (NPDES) 3-25, 3-37
Occupational Safety & Health Administration (OSHA) 3-4 to 3-6, 3-67
Ocean disposal of FGC wastes
costs of 6-8
impacts of 3-61
monitoring of 3-60 to 3-61, 5-3
penalties for 3-57
permits for 3-58
pipeline transport of 2-73
surface craft transport of 2-74 to 2-75, 6-22
Office of Solid Waste (OSW) 3-16
Office of Water Supply (OWS) 3-20
Open dump, use in disposal practices 3-15
Overburden 2-66
Particulate emission limit under NSPS 2-2
Phos-acid industry, use of gypsum stacking 2-36
Pneumatic backfilling of mine fillings 2-69
Ponds for disposal
design of 2-33, 6-14
liners for 2-32, 2-38, 4-12, 4-45
leakage detection from 2-38
permeability of 2-39
pipeline systems for 2-33 to 2-35
Post-closure care of waste disposal sites 3-20, 3-70, 3-84, 6-28
Post-closure land use of waste disposal sites 2-54 to 2-56, 2-87, 4-11
4-25, 4-31, 5-16
Post-mining land use 3-77
Power Plant and Industrial Fuel Act 3-1
Pozzolanic activity, effect on waste properties 4-6 to 4-7
Predisposal monitoring of disposal sites 5-10 to 5-12, 5-19
Regulatory considerations for disposal 3-1 to 3-8
Resource Conservation & Recovery Act (RCRA) 2-112 to 2-113, 3-8 to 3-15
3-35, 3-62 to 3-63, 3-69, 5-1, 5-4, 6-23
Revegetation of disposal sites 3-78 to 3-79, 4-23, 5-14
Runoff from disposal sites 2-55, 3-35, 4-12, 4-21, 4-28
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Safe Drinking Water Act 3-6
Sanitary Landfill 3-15
Scrubber system costs 6-6, 6-10 to 6-12, 6-21
Sedimentation ponds 3-22
Shannon Weaver Diversity Index 5-14
Site design 2-106 to 2-107
Site location of disposal sites 2-86, 4-8 to 4-10
Site selection 2-103 to 2-105, 3-70, 4-42
Sludge compressibility 4-6 to 4-7
Solid waste disposal control under RCRA 3-1], 3-17
Spoil bank method of disposal 2-65
State regulatory control and programs 3-37 to 3-38, 3-73 to 3-74,
3-81 to 3-83
State requirements for disposal of solid wastes
California 3-50
Florida 3-53
Illinois 3-44 to 3-46, 3-55
Kansas 3-48 to 3-49
Maine 3-39
New Jersey 3-41
North Dakota 3-54
Oregon 3-51, 3-83
Pennsylvania 3-42, 3-53
Tennessee 3-43, 3-52
Texas 3-47, 3-83
Stabilization additives 2-47 to 2-49, 2-92, 4-19, 4-44
Storage silos for dry disposal of ash 2-42
Stowing of wastes in active mines 2-70, 4-21
Strip mining of coal mines 2-60
Subsidence, effect on eventual land use 2-82
Sulfate-rich wastes 2-11 to 2-112, 4-3, 4-37, 4-43
Sulfite-rich wastes 2-108 to 2-111, 2-93, 4-3, 4-14, 4-33, 4-37, 5-7
Surface impoundment, for waste disposal 3-70
Surface Mine Control and Reclamation Act 3-7, 3-21 to 3-23, 3-31 to 3-34
3-64, 3-74 to 3-79, 4-30, 5-1
Surface mines, disposal usage 2-60 to 2-62, 4-32, 4-34, 6-18
Surface water quality control under RCRA 3-35 to 3-38
Total oxidizable sulfur (TOS) 4-33
Toxic Substances Control Act (TSCA) 5-12
Transportation costs, for waste disposal 6-18
Underground injection of waste 3-20 to 3-21
Underground mines, use for disposal of wastes 2-67 to 2-71, 4-32, 6-18
Unstabilized sludges 2-93, 4-37 to 4-40
Waste materials as fill 3-78
Water monitoring, methods of 5-7 to 5-9
Water related impact 2-90 to 2-95, 4-26 to 4-27, 4-32 to 4-33, 4-42
Wet ponding costs 6-6, 6-10 to 6-12, 6-21
Wet stabilization process 4-12
Wind erosion of disposal sites 2-95
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing}
1. REPORT NO.
EPA-600/7-80-012e
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE Waste and Water Management for
Conventional Coal Combustion Assessment Report-
1979; Volume V. Disposal of FGC Wastes
6. REPORT DATE
March 1980
6. PERFORMING ORGANIZATION CODE
7 AUTHOR(S)C.J.Santhanam,R.R.Lunt,C.B.Cooper,
D.E.Klimschmidt,I.Bodek, and W.A.Tucker (ADL);
and C.R.Ullrich OJniv of Louisville)
B. PERFORMING ORGANIZATION REPORT NO.
9 PERFORMING ORGANIZATION NAME AND ADDRESS
Arthur D. Little, Inc.
20 Acorn Park
Cambridge, Massachusetts 02140
1O. PROGRAM ELEMENT NO.
EHE624A
nTCONTRACT/GRANT NO.
68-02-2654
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
PERIOD COVERED
14. SPONSORING AGENCY CODE-
EPA/600/13
is. SUPPLEMENTARY NOTES iERL.RTp project officer is Julian W. Jones, Mail Drop 61, 919/
541-2489.
IB. ABSTRACT
rep0rtj the fifth of five volumes , focuses on disposal of coal ash and
FGD wastes which (together) comprise FGC wastes. Disposal of these wastes repre-
sents significant sources of environmental pollution unless proper disposal technol-
ogies are employed. Continued R and D efforts have provided substantial baseline
information on environmentally sound disposal methods. The report assesses the
various options for the disposal of FGC wastes with emphasis on disposal on land.
A number of technical, economic, and regulatory factors appear to encourage inc-
reasing use of dry disposal methods. Regulatory considerations impacting FGC
waste disposal are assessed. Regulations under the Resource Conservation and
Recovery Act, the major Federal legislation impt.cting FGC waste disposal, are
still emerging. An assessment of the monitoring requirements from the viewpoints
of regulation and environmental control is reported. Ongoing studies on the econo-
mics of FGC waste disposal are reported and assessed. Cost estimates for sound
disposal practice are £9 to #15 per dry metric ton of waste. Environmental impact
issues concerning disposal options include physical stability, public policy and land
use, and leachate mobility. A summary of data gaps and research needs in this area
are outlined.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Pollution
Coal
Combustion
Assessments
Management
Waste Disposal
Water
Flue Gases
Cleaning
Ashes
Pollution Control
Stationary Sources
Flue Gas Cleaning
13E
2 ID
21B
14B
05A
07B
13H
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report I
Unclassified
21. NO. OF PAGES
330
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (t-73)
R-14
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