United States
Environmental Protection
Agency
Office of Solid Waste
and Emergency Response
Washington, DC 20460
EPA/530-SW-88-003/>
December 1987
Solid Waste
&EPA
Report to Congress
Management of Wastes from the
Exploration, Development, and
Production of Crude Oil, Natural Gas,
and Geothermal Energy
Volume 2 of 3
Geothermal Energy
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REPORT TO CONGRESS
MANAGEMENT OF WASTES FROM THE
EXPLORATION, DEVELOPMENT, AND PRODUCTION
OF CRUDE OIL, NATURAL GAS, AND GEOTHERMAL ENERGY
VOLUME 2 OF 3
GEOTHERMAL ENERGY
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Office of Solid Waste and Emergency Response
Washington, D.C. 20460
->
U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
December 1987
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TABLE OF CONTENTS
CHAPTER PAGE
CHAPTER I - INTRODUCTION 1
Statutory Requirements and General Purpose 1
Study Approach 2
Study Factors 3
CHAPTER II - DESCRIPTION OF GEOTHERMAL RESOURCES AND THE
GEOTHERMAL INDUSTRY 9
Geothermal Resources Background 9
Exploration and Development Operations 11
Surface Exploration 11
Geothermal Well Drilling 13
Drilling Mud 14
Distribution of Geothermal Drilling Activity 17
Electrical Power Production Operations 17
Vapor-Dominated Systems 19
Liquid-Dominated Systems 21
The Flash Process 21
The Binary Process 24
Annual Producti on 25
Di rect Use of Geothermal Energy 25
Downhole Heat Exchangers 25
Surface Heat Exchangers 28
Current Use 28
CHAPTER III - IDENTIFICATION AND CHARACTERIZATION OF
EXEMPT WASTES 35
Discussion of Exempt vs. Nonexempt Wastes 35
Exploration and Development Wastes 36
Geothermal Power PI ant Wastes 39
Spent Brine for Injection 40
Sludges from Brine Precipitation 42
Estimates of Waste Volumes 42
Waste Generation from Direct Users 43
Waste Characterization 43
Liquid Wastes 45
Solid Wastes 51
Analysis of Waste Constituents 56
Discussion of Data Adequacy 60
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TABLE OF CONTENTS
CHAPTER PAGE
CHAPTER IV - WASTE MANAGEMENT PRACTICES 63
Current Waste Management Practices 63
Waste Management Practices for Waste Products from
Drilling Operations 63
Waste Management Practices for Power Generation
Facilities 66
Direct Release to Surface Waters 67
Closed-Cycle Ponding 67
Injection of Liquid Wastes 67
Injection into a Nonproducing Zone 69
Treatment and Injection 69
Consumptive Secondary Use 70
Waste Management Practices for Direct Users 71
Alternative Waste Management Practices 71
Economic Analysis of Waste Management Practices 80
Cost Estimation Methodology 80
The Estimated Impact of Alternative Waste Management
Practices 81
Forecast of Future Profitability for the Geothermal
Industry 83
CHAPTER V - DAMAGES CAUSED BY GEOTHERMAL OPERATIONS 85
CHAPTER VI - RISK ASSOCIATED WITH GEOTHERMAL OPERATIONS ... 87
Introduction 87
Scope and Limitations 88
Characterization of Major Risk-Influencing Factors 89
Waste Streams 89
Produced Fluid Wastes 90
Production Fluid Wastes — Conventional Steam
Cycle 92
Production Fluid Wastes — Binary Process 93
Production Fluid Wastes — Flash Process 95
Direct User Fluid Wastes 96
Drilling Pit Solid Wastes 96
Waste Management Practices 97
Production Fluid Wastes — Power Plants 99
Production Fluid Wastes —Direct Users 101
Drilling Pit Wastes 102
Environmental Settings 103
Qualitative Risk Assessment Results 104
Underground Injection —Produced Fluids 106
Power PI ants 106
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TABLE OF CONTENTS
CHAPTER
PAGE
Chapter VI - Continued
Direct Users 108
Onsite Reserve Pits—Drilling Wastes 109
Conclusions 110
References 112
CHAPTER VII - CURRENT REGULATORY PROGRAMS 113
Federal Regulations 113
Regulatory Agencies 113
Geothermal Resources Operational Orders 113
Underground Injection Control Program 115
Summary of State Requirements 116
Regulatory Requirements 116
Summary of California's Geothermal Regulations 117
State Regulatory Agencies 117
Geothermal Regulations 117
Permits 123
Well Design 124
Solid and Liquid Waste Disposal 124
Liquid Waste Subsurface Injection 124
Surface Disposal--Water 125
Surface Disposal--Land 126
Well Plugging and Abandonment 129
Surface Restoration 129
CHAPTER VIII - CONCLUSIONS 131
CHAPTER IX - RECOMMENDATIONS 133
APPENDIX A - DATA MANAGEMENT A-1
Data Sources A-l
APPENDIX 8 - ABBREVIATIONS OF UNITS AND SCIENTIFIC TERMS
USED IN THE FIGURES AND TABLES B-l
APPENDIX C - GLOSSARY C-1
APPENDIX D - REPORT BIBLIOGRAPHY D-l
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TABLES
CHAPTER II
PAGE
II-l Summary of Geothermal Drilling Activity by State from
1981 to 1985, Including Production, Injection, and
Wildcat Wells 18
II-2 Site Listing — Power Plants 26
II-3 Site Listing-Direct Users 29
CHAPTER III
III-l Estimated Waste Volumes for Drilling Activities
Associated with Exploration and Development of
Geothermal Resources 38
III-2 Estimated Liquid Waste Volumes from Both Binary and
Flash Process Plants 41
III-3 Estimated Liquid Waste Volumes Resulting from Direct
Use of Geothermal Energy 44
III-4 Power Plant Liquid Analysis Summary 46
III-5 Direct Users Liquid Analysis Summary 47
III-6 Liquid Waste: Test Well Brine Analyses 50
III-7 Metals Detected in the Extracts of Geothermal Brines 52
III-8 Solid Waste: Bulk Composition 53
III-9 Sol id Waste Acid Extract: Bulk Composition 54
111-10 Sol id Waste Neutral Extract: Bulk Composition 55
III-ll Solid Waste Acid Extract: Trace Analysis 57
111-12 Sol id Waste Neutral Extract: Trace Analysis 58
111-13 Metals Detected in the Extracts of Geothermal Solid
Wastes from the Imperial Valley Area 59
CHAPTER IV
IV-1 Waste Disposal Practices for Geothermal Power
Generation Facilities 68
IV-2 Waste Disposal Practices for Direct Users 72
IV-3 Waste Management Practices 78
IV-4 Annualized Per Barrel Surface Impoundment Cost 82
IV-5 Total Annual Cost of Alternative Waste Management
Practices 84
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TABLES
CHAPTER VI
VI-1 Model Production Fluid Waste Stream Analyses 94
VI-2 Drilling Pit Solid Wastes: Bulk Composition 98
VI-3 Environmental Settings at Geothermal Energy
Facilities 105
CHAPTER VII
VII-1 Summary of State Geothermal Regulations 118
VII-2 Summary of Waste Management Strategies for Discharges
to Land 128
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FIGURES
CHAPTER II PAGE
II-l Known and Potential Geothermal Resources 12
II-2 Typical Rotary Drilling Rig 15
II-3 Typical Hydrothermal Well 16
II-4 Dry-Steam Schematic 20
II-5 Flashed-Steam Schematic 22
II-6 Binary Schematic 23
CHAPTER VI
VI-1 Exempt Wastes Generated from Geothermal Energy
Industry Activities 91
VI-2 Waste Management Practices for Produced Geothermal
Fluid Wastes 100
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CHAPTER I
INTRODUCTION
STATUTORY REQUIREMENTS AND GENERAL PURPOSE
Under Section 3001(b)(2)(A) of the 1980 Amendments to the Resource
Conservation and Recovery Act (RCRA), Congress temporarily exempted
several types of solid wastes from regulation as hazardous wastes,
pending further study by the Environmental Protection Agency (EPA).
Among the categories of exempt wastes were "drilling fluids, produced
waters, and other wastes associated with the exploration, development or
production of crude oil or natural gas or geothermal energy." Section
8002(m) of the Amendments requires the Administrator to study these
wastes and submit a final report to Congress. This publication is in
partial response to those requirements. The report is divided into three
volumes and an Executive Summary. Because of the many significant
differences between the oil and gas and the geothermal energy industries,
separate volumes have been devoted to each. Volume 1 covers the oil and
gas industry; Volume 2 (this volume) covers the geothermal energy
industry. Volume 3 provides summaries of State regulations and damage
cases associated with the oil and gas industry, as well as a glossary of
terms.
EPA failed to meet the Congressionally mandated deadline of October
1982 for submission of the final Report to Congress and later, to settle
a suit brought by the Alaska Center for the Environment, signed a consent
order obligating itself to submit the report on or before August 31,
1987. In April 1987, this deadline was extended by the court to
December 31, 1987.
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Since the passage of RCRA in 1976, Congress and the Agency have
expressed growing concern over the problems involved in the development
of a suitable approach for managing high volume solid wastes. Wastes now
exempt from Subtitle C regulation by Section 8002 were originally
included within a category of "special wastes" under earlier RCRA
regulations. Under this classification, Subtitle C regulation was to be
deferred, pending further study of the waste volumes, hazardous
characteristics, and alternative management practices.
Following submission of the current study, and after public hearings
and opportunity for comment, the Administrator of EPA must determine
whether to promulgate regulations under the hazardous waste management
provisions of RCRA (Subtitle C), or to declare that such regulations are
unwarranted.
The recommendations contained in this report do not represent a
regulatory determination, as such a determination is not required until
June 1988. Moreover, in several important areas, the Agency has provided
a number of optional approaches that will involve additional research and
consultation with the States and other affected parties. It does not now
recommend, nor does it foresee any future likelihood of recommending,
wholesale imposition of Subtitle C regulation for the high volume wastes
of concern in this study.
STUDY APPROACH
EPA has endeavored to respond to all of the study factors cited in
Section 8002(m). For clarity, this report has been designed to respond
specifically and individually to each study factor within separate
chapters or subsections of this volume. Although each study factor was
taken into consideration during the course of this study, no single study
factor influenced its conclusions and recommendations.
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The following paragraphs define the study factors and introduce the
methodologies used to analyze them with respect to the geothermal
industry. More detailed methodological discussions can be found later in
this report.
STUDY FACTORS
The principal study factors are listed in subparagraphs (A)
through (G) of Section 8002(m). The introductory and concluding
paragraphs of the section, however, also contain directives to the Agency
on what should be included in the present analysis. This study has
therefore been organized to respond to the following interpretation of
the statutory requirements.
Study Factor 1 - Defining Exempt Wastes
RCRA describes the exempt wastes in rather broad terms. The Agency
has thus largely relied on the legislative history of the amendments,
which provides guidance on the definition of "other wastes." Where the
legislative history does not provide guidance, EPA has had to make
assumptions and interpretations. These assumptions are set forth in
detail in Chapter III, "Identification and Characterization of Exempt
Wastes."
Study Factor 2 - Specifying the Sources and Volumes of Exempt Wastes
In response to subparagraph (A), EPA has prepared estimates of the
sources and volumes of all exempt wastes. The results of this analysis
are presented in Chapter III. Unfortunately, statistics on the volumes
of exempt wastes from geothermal operations are not routinely collected
nationwide. However, estimates of total volumes produced can be reached
indirectly through a variety of approaches. This report presents the
approaches used for these estimates.
3
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Study Factor 3 - Characterizing Wastes
While Section 8002(m) does not explicitly call for a laboratory
analysis of the exempt wastes, the Agency considers such a review a
necessary and appropriate element of this study. Analysis of the
principal high volume wastes can help to determine whether any of the
wastes could be considered hazardous under the definitions of RCRA
Subtitle C. Of the four RCRA tests to determine hazardousness (toxicity,
ignitability, corrosivity, and reactivity), this study is primarily
concerned with toxicity, the factor most likely to contribute to
potential health and environmental damage under field conditions.
Study Factor 4 - Describing Current Disposal Practices
Subparagraph (B) calls for an analysis of current disposal practices
for exempt wastes. Chapter IV, "Waste Management Practices," summarizes
EPA's review, which was based on a number of sources. In addition to
reviewing the technical literature, EPA sent representatives to
geothermal sites of the major geothermal production areas to discuss
current methods and technologies. State and local regulatory agencies
were also contacted to obtain information on their rules and
recommendations for disposal of geothermal energy wastes.
The purpose here has not been to compile an exhaustive technological
review of waste management technologies used by the geothermal industry.
As stressed throughout this volume, conditions and methods vary from
region to region and operation to operation. Thus, the intention of this
volume is to list and describe the principal methods of managing
field-generated wastes, and to discuss these practices in general and
qualitative terms.
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Study Factor 5 - Documenting Evidence of Damage to Human Health and the
Environment Caused by Management of Geothermal Wastes
Subparagraph (D) requires EPA to analyze "documented cases" of
health and environmental damage related to surface runoff or leachate.
No significant damage cases resulting from geothermal energy operations
were found.
Study Factor 6 - Assessing Potential Danger to Human Health or the
Environment from the Wastes
Paragraph (C) requires an analysis of the potential dangers of
surface runoff and leachate. These possible effects can involve all
types of damages over a long period of time, and are not necessarily
limited to the categories of damages for which documentation is available.
There are several methods of estimating potential damages. EPA used
a qualitative approach, based on traditional environmental assessment
techniques, in responding to this study factor in Chapter VI, "Risk
Associated with Geothermal Operations." Overall, the Agency felt that
the quantity and quality of data available did not warrant a quantitative
risk modeling approach at this time.
The goal of the qualitative risk assessment has been to define those
factors that are most important in causing or averting environmental
damages from field operations. The traditional environmental assessment
procedures require no modification in order to be applied here.
The results of the modeling analysis have no statistical
significance in terms of either the pattern or the extent of damages
projected. Resources were available to model only a subset of prototype
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situations, designed to roughly represent significant variations in
conditions across the country. The results are very useful, however, for
characterizing the interactions of technological, geological, and
climatic differences as they influence the potential damages, and have
been used accordingly in reaching the conclusions of this study.
Study Factor 7 - Reviewing the Adequacy of Government and Private
Measures to Prevent and/or Mitigate Any Adverse Effects
Paragraph (1) requires that if the Agency concludes that there are
adverse effects associated with the current management of exempt wastes,
its conclusions must consider the adequacy of the means currently being
used by the geothermal industry and government agencies to dispose of or
recycle wastes or to prevent or mitigate those adverse effects.
Neither the damage case assessment nor the risk assessment could
provide statistically valid data on the extent of damages, making it
impossible, even if resources were available, to compare damages in any
quantitative way to the presence and effectiveness of control efforts.
The Agency's response to this requirement is therefore based on a
qualitative assessment of all the materials gathered during the
preparation of this report, as well as on the review of State regulatory
programs presented in Chapter VII, "Current Regulatory Programs." The
approach in Chapter VII has been to review existing regulatory programs
in order to highlight areas of coverage and approaches to implementation.
Study Factor 8 - Defining Alternatives to Current Waste Management
Practices
Subparagraph (E) requires EPA to analyze alternatives to current
disposal methods. A discussion of this study factor is incorporated in
Chapter IV, "Waste Management Practices."
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This chapter merges the concepts of current and alternative waste
management practices. Waste management technology in this field is
fairly simple as no significant "innovative" or "emerging" technologies
are currently in the research or development stage. Future improvements
in waste management in these industries, therefore, must be based on
more effective use of existing approaches, either through better
implementation and maintenance practices or through more stringent
application of available treatment techniques.
Study Factor 9 - Estimating the Costs of Alternative Practices
Subparagraph (F) calls for analysis of the costs of alternative
practices. Chapter IV presents the Agency's analysis of this study
factor.
Because this industry does not plan to initiate alternative waste
management practices, EPA had to postulate a number of alternative
approaches, many of which are merely more stringent applications of
current practices. These alternatives have been included solely for
informational purposes, not because the Agency feels there is a need for
more rigorous approaches.
Study Factor 10 - Estimating the Economic Impacts of Alternative
Practices on Industry
In response to the requirements of subparagraph (G), sections of
Chapter IV present the Agency's analysis of the potential economic
impacts of nationwide imposition of the alternative practices.
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Because of this lack of alternatives, both the cost and the economic
impact analyses used in this report are admittedly broad. In addition,
reviewers have noted that significant variations influence the economics
of this industry; these variations, such as the costs of fossil fuels and
alternative fuels, make it difficult to generalize about impacts on
either the project or the national level. Thus, it is difficult to draw
conclusions concerning the current and future impacts of modified waste
management practices.
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CHAPTER II
DESCRIPTION OF GEOTHERMAL RESOURCES AND
THE GEOTHERMAL INDUSTRY
GEOTHERMAL RESOURCES BACKGROUND
The crust and the atmosphere of the earth account for less than
one-half of one percent of the total mass of the earth. The remaining
99.5 percent lies beneath the crust. Scientific knowledge of the
material beneath the crust results largely from the study of seismicity
and measurements of the heat-flow from the earth's interior toward the
surface. This knowledge has allowed geophysicists to construct a clear
and consistent model of the internal structure of the earth. The
currently accepted model of the earth's internal structure consists of
four concentric spheres. From the outermost to the innermost, they are
the crust, the mantle, the liquid core, and the innermost core. It is
thought that temperatures and densities rise rapidly as the center of the
earth is approached.
The term "geothermal energy" can be defined as heat energy stored in
the earth. The U.S. Geological Survey estimates that about 1.2 million
quads (a quad is a unit of heat energy, equal to one thousand trillion
British Thermal Units) of geothermal energy resources exist in the
uppermost 10 kilometers of the crust. The resource is represented by
that small fraction of the earth's volume in which high-temperature
crustal rocks, sediments, volcanic deposits, water, steam, and other
gases occur at accessible depths from the earth's surface, and from which
heat can be economically extracted now or in the future. Although small,
this portion of the earth's volume is an enormous reservoir of thermal
energy.
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Many geologists and engineers classify geothermal energy systems
into four major categories:
• Hot igneous systems - created by the buoyant rise of molten
rock (magma) from deep in the crust. In hot igneous systems,
the rock is either completely or partly molten (greater than
650°C).
• Hot dry rock systems - heated impermeable rock that may or
may not have been molten at one time (less than 650°C).
• Geopressured systems - characterized by the presence of hot
fluids under high pressure, containing dissolved hydrocarbons,
usually found in deep sedimentary basins with a low level of
compaction and a relatively impermeable caprock. These systems
reach moderately elevated temperatures (90° to 200°C).
• Hydrothermal systems - usually found in porous sedimentary
rock or in fractured rock systems, such as volcanic
formations. The two classes are vapor-dominated systems, which
contain mostly steam (180° to 200°C), and liquid-
dominated systems (30° to 350°C).
The first three categories contain the most heat energy, but they
are not economically or technologically exploitable at this time.
Federal research programs are currently directed at removing these
hindrances.
The fourth category, hydrothermal systems, has received the most
attention because the technology exists to economically extract energy
from these systems. Hydrothermal systems consist of high-temperature
water and/or steam trapped in porous and permeable reservoir rocks. The
convective circulation of water and steam through networks of faults and
fractures causes heat to rise. The heat available in the geothermal
reservoir rock is produced by wells that bring hot water and/or steam to
the surface.
10
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The locations of hydrothermal and geopressured resource areas are
shown in Figure II-l. Identified hydrothermal systems with temperatures
greater than or equal to 90°C (194°F) are located primarily in
the western United States, while low-temperature geothermal waters are
found in the West, as well as in the central and eastern United States.
Accessible hot dry rock resources are found in young volcanic centers in
the West. Magma resources are generally limited to areas of recent
volcanism in the western States, Alaska, and Hawaii.
EXPLORATION AND DEVELOPMENT OPERATIONS
Surface Exploration
The objective of any geothermal exploration program is to locate
geothermal resource systems from which energy can be profitably
extracted. Rapid, low-cost surface reconnaissance techniques are
employed in the early stage of exploration to screen large land areas for
commercial potential. Surface reconnaissance may include geophysical,
geological, geochemical, and remote-sensing surveys.
A wide variety of geophysical methods are used for surface
geothermal exploration. The objectives of using geophysical methods are
to identify certain geophysical characteristics, such as electromagnetic
or gravitational anomalies, or attenuation of seismic waves, which arise
from contrasts in rock characteristics inside and outside of the
geothermal systems (Hochstein 1982). The geophysical methods selected
depend primarily on the type of geothermal system being explored.
Surface geological methods apply where geothermal leaks in the
earth's surface occur. Surface features such as fumaroles, hot springs,
warm springs, geysers, mud volcanoes, and mud pots are the most direct
and obvious indicators of the presence of subsurface geothermal
11
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INDIANA
^
KENTUCKY
_
TENNESSEE
MISSISSIPPI
L-
LOUISIANA^
Temperature above 90°C (194F°)
Temperature below 90°C (194F°)
Geopressured Resources
o 100 200 300
SCALE IN MILES
Figure 11-1 Known and Potential Geothermal Resources
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reservoirs. Seeps can provide quantitative information on the nature of
these reservoirs and their contained fluids.
Geochemical exploration involves field and laboratory activities
that focus on determining the composition of geothermal liquids and gases
by obtaining and analyzing representative samples. Geochemical
activities also include the prevention of scale deposition, methods for
removing scale accumulations, and techniques for rendering geothermal
liquids suitable for subsurface disposal. Examples of geochemical
activities are the application of chemical geothermometers, measurement
of gas emanations, and quantitative petrographic analyses from the
subsurface, as well as samples of surface outcrops.
Remote-sensing technology, such as infrared imagery, is used to
identify potential geothermal resources. In areas of known geothermal
potential, remote sensing helps to identify surface features such as
faults and joints, and thus aids in the design of more efficient drilling
programs.
Geothermal Well Drilling
Wells are drilled after potential geothermal resources are
identified. Initial exploratory drilling is undertaken to confirm the
existence of the geothermal resource, and to determine its extent and its
physical and chemical characteristics. When a commercially producible
resource is confirmed, further drilling may be required for development
and use. Methods and equipment used for geothermal well drilling are
similar to those used in the petroleum industry.
Figure II-2 shows a typical drilling rig. Drilling difficulties,
such as low penetration rates and short bit lives, result from the
elevated temperatures and hard rocks encountered in typical geothermal
13
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reservoirs (Varnado, et al. 1981). Federal research programs such as the
Geothermal Hard Rock Penetration Program and the Sal ton Sea Scientific
Drilling Program have contributed to the development of improved hardware
that is better able to withstand the harsh subsurface environment
(Varnado, et al. 1981; Wallace, et al. 1987).
One of the most important factors in the construction of a
production well is the provision of high quality steel casing. The
casing supports the borehole wall and prevents fluid migration, which
could lead to ground-water contamination. Figure II-3 is a diagram of a
completed liquid-dominated hydrothermal well with installed casing. As
many as four concentric casings can be installed in a single well. Each
casing is usually fixed with cement to the surrounding rock matrix to
provide additional support.
Drilling Mud
The drilling fluid, usually mud, is a formulation of clay and
chemical additives, such as caustic soda or other materials, in a water
base. This fluid is pumped from a mud pit or tank (Figure II-2) down
through the drill string and circulated up through the annulus (i.e.,
between the drill pipe and the wall of the hole). After removal of drill
cuttings, which are fragments of rocks dislodged by the drill bit, the
mud may be directed to a cooling tower or tank if excessive heating has
occurred downhole. After cooling, the mud is returned to the mud pit or
tank for recirculation.
14
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SHALE SHAKER
MUD TANK
Figure 11-2 Typical Rotary Drilling Rig
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MAIN VALVE
CTi
PUMP
GEOTHERMAL RESERVOIR
CONCRETE PAD
CONDUCTOR PIPE SET AT
20' - 80' (6-24M)
SURFACE CASING
CEMENT
FLUID LEVEL
PUMP TURBINES
AND BOWLS
PRODUCTION CASING
LINER HANGER
SLOTTED LINER
ft.
(m)
100'
(30)
500*
(152)
1,000*
(305)
3,000'
(915)
5,000'
(1,524)
Figure II-3 Typical Hydrothermal Well (Source: USDOE 1981)
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Drilling mud serves multiple purposes. It cools arid lubricates the
drill bit, flushes rock chips from the borehole, and helps prevent
blowouts. The proper selection and management of drilling fluid are
essential to geothermal drilling operations.
The drilling fluids used for penetrating vapor-dominated and
liquid-dominated systems may be similar; however, compressed air rather
than mud is sometimes used as the circulating medium for vapor-dominated
systems because water-based muds can solidify and damage the producing
formation. Liquid-dominated systems are usually drilled with
conventional drilling muds containing high-temperature additives and, at
times, lost circulation material. Ninety percent of muds are composed of
bentonite and water or bentonite and lignite (Robinson 1987). Various
types of drilling muds may be used, but the type and composition of the
mud depend largely upon the downhole conditions. After the drilling
operations are completed, the used drilling fluids constitute the major
waste source.
Distribution of Geothermal Drilling Activity
Table II-l presents data on the locations of geothermal drilling
activities in the United States during the years 1981 through 1985
(Williams 1986). Thermal gradient holes, which are holes drilled to
measure the temperature profile, are not included in this tabulation. As
shown in the table, California has, by far, the most activity. The
Geysers and Imperial Valley are the primary development sites.
ELECTRICAL POWER PRODUCTION OPERATIONS
There are economically viable methods for producing electrical power
from either vapor- or liquid-dominated systems. The high-temperature
steam found in vapor-dominated hydrothermal systems can be used directly
17
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Table II-l Summary of Geothermal Drilling Activity by State
from 1981 to 1985, Including Production, Injection,
and Wildcat Wells
Number of wells
1981
1982
1983
1984
1985
Total
Alaska
Cal ifornia
Colorado
Hawaii
Idaho
Louisiana
Montana
New Mexico
Nevada
New York
Oregon
Texas
Utah
Washington
Total
-
55
1
2
6
1
-
6
14
-
3
-
-
2
90
4
67
-
1
-
-
1
3
2
1
-
1
2
1
83
-
47 88
-
-
3
-
1
3
4 3
-
1
1
1 2
_
61 93
4
64 321
1
3
9
1
2
12
3 26
1
1 5
2
5
3
68 395
Source: Williams 1986.
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to generate electricity. The hot, saline waters found in
liquid-dominated systems can transfer heat to a secondary working fluid
or be converted to steam by a flashing process.
Vapor-Dominated Systems
The Geysers in California is the largest geothermal electrical
generating complex in the world. It is also the best known
vapor-dominated hydrothermal reservoir under commercial development and
operation in the United States.
Electrical power is generated from a vapor-dominated system, such as
The Geysers, using the conventional steam cycle (see Figure II-4). The
steam from a vapor-dominated system is piped from the production well to
a manifold where it provides direct power to drive the turbine
generator. Production wells are connected to a gathering system composed
of carbon steel pipes. A separator is located on the main steam line to
remove solids from the steam prior to entry into the turbine.
Approximately 2,000 pounds per hour of steam are required to generate one
megawatt. Thus, over one million pounds of steam per hour (a low
estimate) is needed to power one 55-megawatt plant (USDOE 1980a). The
number of wells required to supply this amount of steam depends upon the
individual production from each well. Typically, 10 to 14 wells are
required per 55-megawatt plant.
The exhaust steam from the turbine is condensed, then the condensate
is pumped to a cooling tower where it is cooled and reused as a cooling
medium. The cooling tower acts as a concentrating unit for dissolved
solids in the condensate. The excess condensate is processed to remove
suspended solids. The condensate, which now contains a limited amount of
solids, is injected into the geothermal reservoir, and the resulting
sludge from the pit is dewatered. The disposal method for the filter
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TURBINE GENERATOR
FROM
0 PRODUCTION
WELLS
COOLING TOWER
\ SP
GAS
REMOVAL"
-0
TO
INJECTION
WELLS
CONDENSER
Figure 11-4 Dry-Steam Schematic (Source: DOE 1986)
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cake from the dewatered sludge is determined by the applicable State
regulations.
The electrical generating capacity at The Geysers surpassed
1,000 megawatts late in 1982 when Pacific Gas and Electric Company
(PG and E) Unit 17 began operation (California Division of Oil and Gas,
1983). In 1985, four power plants were brought on-line at The Geysers
geothermal field:
• PG and E Units 16 and 20 (each generating 113 megawatts, net);
• The California Department of Water Resources Bottle Rock
Power Plant (generating 52 megawatts, net); and
• The Northern California Power Agency (NCPA) #2 (Unit 2,
generating 110 megawatts, net).
Today, 24 plants generate 1,800 megawatts at The Geysers. Unocal,
the major steam supplier, and the other four field operators are
responsible for the extraction of steam from The Geysers geothermal
reservoir and injection of any returned condensate (Morton 1986).
Liquid-Dominated Systems
Two processes are commonly used to produce electricity from
liquid-dominated geothermal reservoirs: the flash process and the binary
process. Figures II-5 and II-6, respectively, present flow diagrams of
these two processes.
The Flash Process
The flash process uses the conventional steam cycle in which
geothermal brine is "flashed" to produce the steam. The flash process is
the partial evaporation to steam of the hot liquid brine by the sudden
reduction of pressure in the system. The steam from the flash step is
21
-------
TURBINE GENERATOR
ro
ro
FLASH
SEPARATOR
\
TO
INJECTION
WELLS
FROM
PRODUCTION
WELLS
COOLING TOWER
GAS
REMOVAL'
TO
INJECTION
WELLS
CONDENSER
Figure 11-5 Flashed-Steam Schematic (Source: DOE 1986)
-------
TURBINE GENERATOR
HEAT
EXCHANGER
FROM
PRODUCTION
WELLS
TO
INJECTION
WELLS
COOLING TOWER
CONDENSER
\ °P
TO
INJECTION
WELLS
MAKEUP
WATER
Figure 11-6 Binary Schematic (Source: DOE 1986)
-------
fed directly into the turbine, with subsequent usage and disposal as
described in the subsection on vapor-dominated systems.
The Vulcan Power Plant in California's Imperial Valley, owned by the
Magma Power Company, is an example of a liquid-dominated system that uses
a flashing process to generate electricity. The power plant is designed
to produce 35 megawatts, net, of electricity from the high-temperature,
highly saline geothermal fluid in the Salton Sea area.
The Binary Process
The 45-megawatt Heber Demonstration Plant, also in California's
Imperial Valley, is the largest binary power plant in the world
(California Division of Oil and Gas 1985). The Heber Plant uses a simple
binary-cycle conversion process consisting of three fluid loops: a
geothermal fluid loop, a hydrocarbon working-fluid loop, and a cooling
water loop. The binary process uses brines in the 150° to 210°C
(320-410°F) range.
The geothermal fluid is withdrawn from the reservoir into the
production well. The geothermal brine passes through two parallel
brine/hydrocarbon heat exchangers at the rate of about 8 million Ib/h.
The brine and hydrocarbon are contained in separate closed loops,
allowing no direct contact with the atmosphere. The hydrocarbon vapor
expands through the turbine, which drives the 70-megawatt electric
generator. Spent brine is injected into the geothermal reservoir at
about 72°C (162°F). The brine temperature must be kept above
65°C (149°F) to prevent precipitation of dissolved solids prior
to injection. Brine that passes through the turbine and brine that
passes only through the heat exchanger and is then directly injected are
exempt wastes.
24
-------
Annual Production
Table II-2 lists 25 geothermal power facility sites that are either
operating or are under construction in the United States. A "site" is
defined as either a single power plant or a multiple operating unit. For
example, power-generating facilities at The Geysers are shown as five
different sites, although these five sites contain 25 operating units,
owned by five different power companies. Ninety-six percent of the
geothermal power plant electrical capacity is found in California alone;
the remaining four percent is distributed throughout other States.
DIRECT USE OF GEOTHERMAL ENERGY
In some areas of the country, it is often efficient and economical
to use geothermal energy as a direct source of heat. This heat can be
extracted from the condensate from an electrical generating facility or
directly from a geothermal production well. Direct applications require
less capital than do power plants and can be developed on a relatively
small scale; therefore, they are more common. The high cost of
transporting available heat to the point of use has limited the
development of multiuser direct heat systems to areas near geothermal
sources. The two most common types of direct application of geothermal
energy are downhole heat exchangers and surface heat exchangers.
Downhole Heat Exchangers
Some 400 to 500 shallow wells are used for space heating in the
Klamath Falls and Klamath Hills, Oregon, geothermal areas (Geonomic 1978;
Lienau 1986). These wells provide heat for about 500 homes, offices,
commercial buildings, schools, churches, and greenhouses (Lienau 1986).
Typically, well temperatures range from 38° to 110°C (100° to
230°F). Most of the wells use downhole heat exchangers, which
consist of one- or two-tube loops suspended in the wellbore, in direct
25
-------
ro
CT)
HAM!
FA- : ft .A
(A „! ME .A
IAS1 HEi A (b ( MfCABE NO 1 )
MEEuR
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(0 0
wn.oii L AM; Oil (HOI.; v LA-E)
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^HE GlVifhS
THE GE V.ERS
i|-:i Gi r H'-. (bOi'lE ROC' )
Till G! Y ,fRS
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THE f.i Y ,ER:
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I 1'SHI I(o DOC I
EfRAJY HAZEN
UI/H v;itn - oxbow
Fi .rl I A* f
OWI.fi
MAf;Mf POWER LO
MEbtR GEOihtRMAi CO
^.Ii-Af b I NARY OEMj
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MAC.MA POWtR LO
( Al hORMA EMER'SY CO
.SlOiROD'ILTS
Wll.'. A;lt OEVEICPER
MAt'Mj'H PAL K 1C
PAL If i( fiAS t,
ELECTRIC CO
SACRAMENTO MUNICIPAL
UTILITY DISTRICT
NORTHERN CALIFORNIA
POWER AGENCY
CALIFORNIA DEPT Of
WAT-R RESOURCE',
FRIEPORI HACMOkAN
SAI.TA fE GEOIHERMAL
(C.PA
HELLO
BURGET1 FLORAL .
CHEVRON
OXbOW GtOTHERMAL
STEAM RESERVE CORP
(RESCiNT VALLEY
GEOIHERMAL (SUt^lD 0' ,CE)
Si /COUNTY
(.A IMHcklAl
LA IMPERIAL
CA IMPERIAL
LA IMPERIAL
LA IMPERIAL
LA IMPER1AI
LA IMPERIAL
LA INYO
(A LASSEN
LA lASSEN
C A MONO
CA SONOMA
CA SONOMA
LA SONOMA
LA SONOMA
LA SONOMA
CA SONOMA
(A SONOMA
HI HAWAII ISLAND
NM HIDALGO
NV CHURCHILL
NV CHURCHILL
NV ESMERALDA
IIV LANOER/EUREK.A
fi-OCE':-"
ivpt
IPB
LPe
LPb
ipr
LPB
LK
iPr
LPF
LPH
LPb
IPb
VP;
VP;
VP.
VP;
VPC.
VP.
VPS
LPf
LPb
LHP
LPK
LPE
LHf
ELELTRILAL
CAPACITY (MW)
\f GO >JC
24 00 OP
12 % OP
4? OC OP
4C, 00 OP
\'j CC OP
34 ',0 OP
2S 00 OP
20 00 UC
0 LO OP
7 00 OP
ieeo oo OP
n oo OP
220 00 OP
5S 00 OP
60 00 OP
bO 00 OP
!r,0 00 UL
3 00 OP
0 90 OP
8 30 OP
SO 00 UC
IS 00 UC
17 00 OP
-------
lAbLF 1 \-t Uont n.jtc)
f.Ar'E
WAtsiSt A Hdi '.I'RIfi i
DE'HR: f-:AI
FGPI
- SUlPhJRBALf
ROC-EVEI T HOI
- KILFGPC
F i-,t I el It.•
V-VafJ'J'
I -L IQuHl
OWNFR
TAD'S
CriEVRC
PACIF]
GEOTHE
ASSOtIATES
MOTH
INDU
UPfcL
second letter
P- Fov/c-r 'jenef dt ion
m-^isE.
SIERRA
POWER CO
'.AL DEVELOPMENT
Uc
J
iAPTH
IES, CITY OF PROVO
>[ Y FOR PROCESS TYPE
Third 1 fetter
ST /COUNTY
NV LYOH
IW RENO
NV WASHOE
UT BEAVER
UT BEAVER
E lect r icdl
PROCESS
TYPE
LPfc
LPf
LPB
iPE
LPF
Cdpciu It y
ELECTRICAL
CAPACITY (MW)
C 60 OP
9 00 0^
6 40 OP
4 70 OP
20 00 OP
F-Flash Process
B-B mary Process
S-( onver.t ior,d 1 Stedin
H-Hybrid
MW-Megdwatts
OP-Operdting
UC-Urider Construction
-------
contact with the hydrothermal fluid. Downhole exchangers have the lowest
investment cost of all types of heat exchangers, but downhole exchangers
are feasible only where reservoir depths are typically less than 500 feet
(Zimmerman, 1984). In most cases, the water inside the heat exchanger
cycles thermally. Therefore, pumps are not required to extract the water
and the need for fluid disposal is eliminated (Zimmerman, 1984).
Surface Heat Exchangers
Unlike downhole exchangers, surface exchange systems require
extraction of geothermal fluid from the reservoir and, subsequently, some
means of spent fluid or brine disposal. Applications of this type of
energy system are numerous, ranging from residential heating to various
commercial uses. One such application is the Pagosa Springs Geothermal
District space heating system, which successfully uses low-temperature
(60°C) geothermal fluid for space heating in public buildings,
school facilities, residences, and commercial establishments at
significantly lower cost than conventional fuels (Goering, et al. 1984).
Current Use
Table II-3 presents a listing of 122 direct-use commercial and
community operations indicated in the literature as currently operating
in the United States. This table includes process type, owner, location,
and daily brine flow rates.
The geographical locations of direct users are much more widespread
than those of electric power generation facilities. This is due, in
part, to the fact that direct applications employ a wider range of
temperatures than do electric power generation facilities.
28
-------
TABLE II-•
>IH LIST I NG--[.)ir.c(T USER.
UD
NAME
CHEN A HOI SPRINGS
CIRCLE HOI SPRIGS
MANLEY hO! SPRINGS
MfLOZI HOI SPRINGS
HOT SPRINGS NAT10NAI
N1LAN!)
SAtTON CITY
CRAfclREE HOI SPRINGS
S'JSAtWIUE
SUSANVIUE
SUSANVILlt - NURSERY
WENDELL-AWE DEE
CEDARVILLE HIGH SCHOOL
ELEMENTARY SCHOO:
FORT BIDWEIL
FORT 6IDWELL-DISTRI
FORT BIDWELl - f ISH
MAMMOTH L'AFES
MAMMOTH LAI ES-DIiTR
MAMMOfH LAl'ES-nSri
INDIAN UlLt Y HOT SPRINGS
(GREtNVKLf)
COACHELLA
letter
L -E iqj id
OWNER
PRIVATE OWNERSHIP
PRIVATE OWNERSHIP
PRIVATE OWNERSHIP
PRIVATE OWNERSHIP
PARK u; GCVT
ENGLEP FISH FARMS
CROCKER ENTERPRISES
US GOVT
CITY OF SUSAIWILLE
LITCHF1ELD CORRECTIONAL
INSTITUTE
PRIVAIE OWNERSHIP
RAMCO RESOURCES
IOL t. MODOC COUNTY
INDIAN RESERVATION
.T HEATING INDIAN RESERVATION
INDIAN RESERVATION
NOT FOUND
CT HEATING
'RINGS INDIAN VALLEY
HOSPITAL
TAKASrilMA NURSERIES
KEY FOR PROrtSS
Second Letter
D-Direct Use
ST/COLINTY
AK OOYON
AK DOYON
M DGYON
AC DOYON
AR GARLAND
CA IMPERIAL
CA IMPERIAL
(A LAKE
CA LASSEH
CA LAS SEN
CA LASSEN
CA LASSEN
CA MODOC
CA MODO:
CA MCDOC
CA MODOC
CA MONO
CA MONO
CA MONO
CA PLUMAS
CA RIVERSIDE
TYPE
Third
S-Space Heating
&ROCES!
TYPE
LDP
LDS
IDS
LDS
LD
IDF
LD
LD
LDD
.Di
LOG
LOG
LDS
LDF
LDD
LDF
LD
LDD
LDF
ID1
LDS
Letter
F-Fish
fcRINE
(LOW RATE
(MGD)
0 3C
0 19
0 2\
0 19
0 00
0 00
0 00
0 Cl
0 11
\ 37
0 43
0 66
0 18
0 43
0 04
0 43
0 00
2 46
0 10
0 41
2 8c
Farm
D-District Heating G-Greenhouse
P-Pool I - Industrial
MGD - Million cjdllorii per day
Sou ret Appendix A
-------
TABLE 11-3 (continued)
GO
O
NAME
ELS1HORE HOT SPRINGS
MECCA
SAN BERNADINO-DISTR1CT
HEATING
SAN BEP'
-------
lABLf 11-3 (continued)
NAMt
GARDEN VALLEY
HOT SPRINGS
CAlDWELL
NAM! A
HOOKER SPRINGS
ALMO
BURlEY
CROOK'S GREENHOUSE
MALAD CIFY
BANKS
BRi'NEAU
H'Jl SPRING1.
M/,RC ING
BUh
fiuHi :A'. KIN-
BUM' II INI
Bum -M&I
Ciiil! -"AY
TWIN FALLS
WARM SPRINGS S1ATF HOSPITAL
ENNIS
ENNIS
WHITE SUUUR SPRINGS
F i r 11 I e 11 e'
L-L iqu id
OWNER
WARM SPRINGS GREENHOUSE
CORRAL
CAl DWELL MUNICIPALITY
NAMPA CITY
HOOPER ELEMENTARY
LDS CHURCH
PRIVATE OWNERSHIP
CROOK'S GREENHOUSE
MALAD HIGH SCHOOL
PRIVATE OWNERSHIP
PRIVA1E OWNERSHIP
PRIVATE OWNERSHIP
PRIVATE OWNIRSH1P
ROBERT LUN1Y
ROeOi LUN1Y
CAL FLINT FLORAL
FLINT GREENHOUSES
MS.L GREENHOUSES
FISH BREEDERS OF IDAHO
COLLEGE OF SOUTHERN ID
AL WARM SPRINGS HOSPITAL
MONTANA LUMBER CO.
MONTANA LUMBER CO.
FIRST NATIONAL BANS-
ST/COUNTY
ID BOISE
ID CAMAS
ID CANYON
ID CANYON
ID CARIBOU
ID CASSIA
ID CASSIA
ID CASSIA
ID ONE I DA
ID OWYHFE
ID OWYHEE
ID OWYHEE
ID OWYHEE
ID TWIN FALLS
10 TWIN FAI IS
ID TWIN FALLS
ID TWIN FALLS
ID TWIN FALLS
ID TWIN FALLS
ID TWIN FALLS
MT DEER LODGE
MT MADISON
MT MADISON
MT MEAGHER
PROCESS
TYPE
LOG
LDS
LDS
LOS
LDS
LDS
LDS
LDij
LDD
LOG
LOG
IDG
iDG
LDG
Ldl
LPf.
IUG
LDG
LDF
LDS
LDS
LDS
LDS
ID'
BRINE
FLOW RATE
(MGD)
0.43
0 04
1 14
1.04
0.30
0 29
0 13
0 01
0.48
0 19
0 36
0 49
0 09
0 03
J --8
C 45
O.ftG
1 01
11 bC
1 73
0 09
0.0-1
0 03
0 09
KEY FOR PROCESS TYPE
Second Letter
D-Direct Use S-Space
Third I etter
Heat ing
D-Distr ict Heat ing
P-Pool
F-Fish Farm
G-Greenhouse
I-Industi ial
MGD - Million gi lions per day
Source. Appendix A
-------
TABLE 11-3 (continued)
CO
ro
NAME
WHITE SULFUR SPRINGS
AVON
LOl.0
JEMEZ Sf RINGS
LAS AITURAS
LAS CRUCES SPACE HTG &
GREENHOUSE
APPACHE TEJO {, KENNECOT!
WARM SPRINGS
5! LA HOI SPRINGS -SPACE
HTG «. POOL
AN I MAS
AM MAS
AiilM.'A
H'UI" 0- fONSr.Oi.triCCS
RING
RflUi - I'OGI
HOI SPRING",
CARL IN (ri P. )
ELKO HOI SPRINGS
ELKO JUNIOR HIGH SCHOOL
CAL IENTE SPALE HEATING
First I fctter
L-L iqu id
OWNER
WHITE SULFUR SPRINGS
MOTEL
EARTH ENERGY INSTITUTE
PRIVATE OWNERSHIP
.NOT FOUND
LAS ALTURAS ESTATES
NEW MEXICO STATE
UNIVERSITY
KENNECOTT CORP
NOT FOUND
bURGETT FLORAL
BE ALL COMPANY GREENHOUSE
MCCANT GREENHOUSE
CITY OF T OR C
CITY OF RENO
PRIVATE OWNERSHIP
GEOTHERMAL FOOD
PROCESSORS, INC
CARL ING HIGH SCHOOL
ELKO HEAT COMPANY
ELKO COUNTY
NOT FOUND
Kf Y FOR PROCESS TYPE
Second Letter
D-Direct S-Space
D-Oistr
P-Pool
SI/COUNTY
MT MEAGHER
MT M1SSOULA
MT MISSOULA
NM SANDOVAL
NM DONA ANA
NM DONA ANA
NM GRANT
NM GRANTS
NM HIDALGO
NM HIDALGO
NM HIDALGO
NM SIERRA
NV WASHOE
NV WASHOE
NV CHURCHILL
NV ELKO
NV ELKO
HV ELKO
NV LINCOLN
PROCESS
TYPE
LDS
LOG
LDS
LDD
LDS
LOS
LDI
LOS
LOG
I Ou
IRS
ir,:
LDS
LDP
I D!
LDS
LDD
LDS
LDS
BRINE
FLOW RATE
(MGD)
0.58
0 02
0 12
0 04
0.00
0.60
1.09
0 20
0 34
0 10
0 0^
o 0':.
0.72
0 16
1 03
0.23
1 01
0 43
0 07
Third Letter
Heat ing
let Heating
F-Fish Farm
G-Greenhouse
1- Industr lal
MGD - Million ga lions per day
Source Appendix A
-------
TABLE 11-3 (continued)
CO
CO
NAME
SPACE H1G & POOL
CALIENTE
WA6US*A
FIRST CHJRCH Of RfLlGIOUS
SCIENCE
VETERANS ADMINISTRATION
MEDICAL CENTER
MOANA GEOTHERMAL AREA
MOANA GEOTHERMAL AREA
WELLS (H P )
AUBURN
MERRILL
KLAMATH FALLi-D'STR KT hTG
KLAMAfH FALLS DISTRICT hTG
KLAMAIH FALLS - i-OOL
KLAMATH FALLS-SPACE HIG
KLAMAIH f-ALI^-bPArf HTG
hUNIERS HOT SPRINGS
LAKE VIEW - GREENHOUSE
LAKEV1EW - POOL HEATING
LAKEVIEW - SPACE HEA11HG
SUMMER LAKE
VALE
VALE
First letter
L-Liquid
OWNER
)OL NOT FOUND
ALEXANDER DAWSOH co
FIRST CHURCH OF
RELIGIOUS SCIENCE
VETERANS ADMINISTRATION
MEDICAL CENTER
WARREN ESTATES
SIERRA GEOTHERMAL INC.
WELLS RURAL ELECTRIC CO
CAYLIGA COMMUNITY COLLEGE
& EAST MIDDLE SCHOOL
PRIVATE OWNERSHIP
G CITY OF KLAMATH FALLS
G OREGON INST OF TECH
PRIVATE OWNERSHIP
PRIVATE OWNERSHIP
PRIVATE OWNERSHIP
COMMERCIAL RESORT
PARKERS GREENHOUSES
PRIVATE OWNERSHIP
PRIVATE OWNERSHIP
COMMERCIAL RESORT
INDUSTRIAL
SUNDECO OREGON TRAIL
MUSHROOM CO.
KEY FOR PROCESS TYPE
Second Letter
D-Duect * S-Space
ST/COUNTY
NV LINCOLN
NV LYON
NV WASHOE
NV WASHOE
NV WASHOE
NV WASHOE
NV WELLS
NY CAYUGA
OR KLAMATH
OR KLAMATH
OR KLAMATH
OR KLAMATH
OR KLAMATH
OR KLAMATH
OR LAKE
OR LAKE
OR LAKE
OR LAKE
OR LAKE
OR MALHEUR
OR MALHEUR
PROCESS
TYPE
LDS
LDF
LD
LD
LDD
LD
LDS
LDS
LOG
LDD
LDS
LOP
LDS
LDS
LOS
LOG
LDP
LDS
LDP
L01
LOG
BRINE
FLOW
RATE
(MGD)
0 22
0 00
0 09
0 43
0.43
0 22
0.07
0 22
0 14
0 40
1.04
0.04
0 50
2.08
0 10
0 14
0 03
0.10
0.03
0 43
0.12
Third Letter
Heat ing
F-Fish Farm
D-Distnct Heating G-Greenhouse
P Pool I-Industnal
MGD = Million gallons per day
-------
TABLE II-3 (continued)
NAME
COVE HOT SPRINGS
HOT SPRINGS
PHlL.'P-GREfNHOUSE
PHILIP DISTRICT HEATING
ST MAR^ 'S HOSPITAL
MARL IN
I-H-S MEMORIAL HOSPITAL
CORSICANA
NEWCASTLE
BLUFFIALE
SANDY
UTAH STATE PRISON
SOL DUG HOI SPRINGS
SFia H1G 'j Wi
Ef'HRAlA
YAM MA
LANDER
IHtftM'JPOi ii
JAC",SON
First Letter
L-L iqu id
OWNER
COMMERCIAL POOL
PRIVATE OWNERSHIP
PRIVATE OWNERSHIP
CITY OF PHILIP
ST. MARY'S HOSPITAL
MARL IN CHAMBER OF
COMMERCE BUILDING
NO! FOUND
NAVARRO COLLEGE
CHRISTENSON BROS
UTAH ROSES
UTAH ROSES
STATE OF UTAH
PR; ATE ow
-------
CHAPTER III
IDENTIFICATION AND CHARACTERIZATION OF EXEMPT WASTES
DISCUSSION OF EXEMPT VERSUS NONEXEMPT WASTES
To assess the potential for environmental impact of wastes generated
by the geothermal industry, the Agency first had to identify which waste
streams resulting from exploration, development, and production
operations are exempt under RCRA 3001(b)(2), and then characterize those
waste streams. Using selection criteria derived from RCRA's language and
the accompanying legislative history, EPA has determined that the
following geothermal energy wastes are temporarily exempt from being
regarded as hazardous under Section 3001(b)(2) and are therefore within
the scope of this study:
• Drilling media and cuttings;
• Fluids from geothermal reservoirs;
• Piping scale and flash tank solids;
• Precipitated solids from brine effluent;
• Settling pond wastes;
• Hydrogen sulfide wastes;
• Cooling tower drift; and
• Cooling tower blowdown.
These exemptions extend only to certain wastes generated during the
exploration, development, and production of geothermal energy.
35
-------
Geothermal wastes that are not exempt and are beyond the scope of
this study include the following:
• Wastes originating in the electric generator;
• Waste lubricants;
• Waste hydraulic fluids;
• Waste solvents;
• Waste paints; and
• Sanitary wastes.
In dry-steam power generation (The Geysers), most waste streams are
produced from materials passing through the turbine and are exempt.
Generation of these wastes—largely hydrogen sulfide abatement wastes--is
intrinsic to the production of geothermal energy. These wastes should be
removed before the fluid is injected back into the geothermal reservoir
in order to maintain the integrity of the injection well and the
geothermal reservoir. In flashed-steam and binary power plants, any
waste resulting from a geothermal fluid or gas that passed through the
turbine is exempt. If the geothermal product passes only through the
heat exchanger (binary process) or flash separator (flashing process),
the resulting waste stream is exempt. Most direct-use waste streams are
exempt wastes.
EXPLORATION AND DEVELOPMENT WASTES
Well drilling activities generate the bulk of wastes from geothermal
exploration and development operations. In general, exempt wastes from
well drilling are drilling muds and drill cuttings. Well drilling
operations generate large quantities of wastes consisting of discarded
drilling muds and residues from drilling mud cleaning processes. Used
drilling muds are cleaned by circulation through equipment that removes
solids, such as shale shakers, sand traps, hydrocyclones, and centrifuges.
36
-------
After cleaning, the mud is recycled to the drilling operations and the
removed solids are disposed of as waste residue.Further treatment of
recycled muds, in the form of additives, is required to control mud
characteristics such as pH and viscosity. Drilling muds are discharged
to reserve pits for storage or disposal, or when the drilling mud system
must be purged because of a change in drilling conditions.
There is little documentation of the volumes of drilling muds and
cuttings generated. One study (USDOE 1980a), based on 50 wells drilled
in the Imperial Valley of California, indicated that about 600 metric
tons of mud and cuttings resulted from drilling a typical 1,500-meter
well. Because of the scarcity of waste generation data, a methodology
was developed to estimate waste volumes of drilling muds and cuttings.
For the annual drilling activity, shown in Table III-l, the average
values for well depth and diameter were determined by geothermal resource
area. These average dimensions were calculated from site-specific well
data contained in the data base. For States without such data, average
well dimensions were estimated from fluid flow rate, fluid temperature,
and intended use of the well.
Volumes of cuttings for specific geothermal areas were calculated
from the number of wells in the area and their average depths and
diameters. From this calculation, an associated mud volume was computed,
based upon a cuttings/drilling mud conversion or correlation factor
derived from site-specific drilling information (Morton 1986). In
preparing Table III-l, cuttings and drilling mud waste volumes were
combined, converted to thousands of barrels, and summarized for the years
1981 through 1985.
37
-------
Table III-l Estimated Waste Volumes for Drilling Activities
Associated with Exploration and Development
of Geothermal Resources
Total mud and cuttings volume
California
The Geysers
Imp. Valley
Other
Nevada
Idaho
Montana
Wyoming
New Mexico
Oregon
Washington
Utah
South Dakota
North Dakota
Hawai i
Total U.S.
1981
(thousands
1982 1
103.8
59.5
43.3
1.0
1.0
NA
0.1
NA
1.4
0.1
0.1
2.3
NA
NA
2.5
111.3
of barrel
983
51.2
46.2
3.9
1.1
2.0
0.3
0.1
NA
NA
0.1
NA
1.2
NA
NA
NA
54.9
s)
1984
198.9
52.2
145.6
1.1
1.0
NA
NA
NA
NA
NA
NA
2.3
NA
NA
NA
202.2
NA - No Activity
Source: See Appendix A.
38
-------
GEOTHERMAL POWER PLANT WASTES
Wastes generated from geothermal power production include spent
brine, flash tank scale, separated solids from pre-injection treatment of
spent brines (Royce 1985), and hydrogen sulfide abatement wastes.
Depending upon the nature of the geothermal fluid, scale formed in
process lines, valves, and turbines must also be removed. The scale
formed generally consists of heavy metal salts and silica. The amount
and composition of these wastes are highly dependent upon the site's
mineralogy and the type of process used for power production. Hydrogen
sulfide abatement constituents include iron sulfide sludge and iron
catalysts used to precipitate hydrogen sulfide; emulsion waste from the
froth tank, vanadium catalysts, and elemental sulfur from the peroxide
extraction process; and sulfur dioxide and sulfur dioxide diluted with
water. In California, these wastes are incinerated or placed in a
Class 1 landfill for hazardous waste.
Very little information describing and quantifying these wastes was
found in the literature review. Most of the available information was
derived from areas such as The Geysers and the Imperial Valley, which
have the most commercial activity. To estimate waste volumes from
geothermal power plants, different approaches were developed, depending
upon the amount of detail available for each geothermal site. PG and E
verified that all condensate is cycled through cooling towers prior to
injection, thus making the injection fluids an intrinsic part of the
production of geothermal energy. Injection is important not only as a
method of disposal but also for reservoir fluid volume maintenance.
Brine flows for both binary and flash power production processes
were calculated from equations derived from a plot of hydrothermal fluid
requirements versus fluid temperature (Zimmerman 1984). The following
equations were generated by extrapolation of data points taken from the
above-referenced plot:
39
-------
Binary Process:
Kilograms Brine/Kilowatt Hour = 583,903-4.141°C+(0.007611°C)
Flash Process:
Kilograms Brine/Kilowatt Hour = 456.78-2.576°C+(0.003855°C).
Hydrothermal temperatures were obtained from four sources (DiPippo
1986; U.S. Geological Circular 790, 1978; and California Division of Oil
and Gas 1984 and 1985). They were coupled with site-specific power
ratings to calculate the daily volumes of brine throughput. (See
Appendix A for development of data.) To this daily flow throughput, an
annual operating factor of 90 to 95 percent (depending on factors such as
type of process and plant age) was applied to obtain brine volume for a
particular facility (see Table III-2). The waste volumes presented in
Table III-2 (in billions of gallons per year) are considered conservative
since no loss is assumed to result from solids formation or evaporation
prior to disposal.
Spent Brine for Injection
Removed impurities from steam at The Geysers are exempt waste. They
are generated from excess steam condensate that is discharged from the
cooling tower before injection. The solids and sludge from The Geysers
are generally considered hazardous wastes and are treated in accordance
with required California State regulations.
Spent brines from operations in the Imperial Valley consist of both
brines that have passed through the turbine and those that have not.
They are also injected (Morton 1986) into the producing zone, but in much
larger quantities than at The Geysers. Brines from binary systems are
maintained under set temperatures and pressures to prevent precipitation
of dissolved solids. This practice allows injection of almost
100 percent of the geothermal fluid.
40
-------
Table III-2 Estimated Liquid Waste Volumes from Both Binary
and Flash Process Plants*
Billions of
State Number of sites gallons per year
California 9 43.70
Nevada 5 9.26
New Mexico 1 .24
Hawaii 1 .06
Utah _2 3.17
Total 18 56.43
*Plants that are currently operational; does not include the
estimated volume for three facilities under construction.
Source: See Appendix A.
41
-------
Brines produced at the flash plants require treatment before
injection because of their very high dissolved solids content (Morton
1986). This treatment results in a solid precipitate that is hauled away
from the site and disposed of according to State regulations for solid
wastes. Between 80 and 90 percent of the brine is injected after this
treatment. Brine injection wells are considered Class V under the
Federal Underground Injection Control (UIC) Program. (See Chapter VII
for details on the UIC Program.) Class V includes wells used for
electric power injection, direct heat injection, heat pump/air
conditioning return flow wells, and ground-water aquaculture wells.
Sludges from Brine Precipitation
One method of treating geothermal brine is to allow precipitation of
dissolved solids in spent-brine holding ponds. The holding pond at the
East Mesa site in the Imperial Valley has sufficient residence time to
allow clarified liquid to be withdrawn from the end opposite the inlet
and injected into the producing reservoir. Solids accumulating in the
pond are dredged, dried by evaporation, and disposed of at the type of
landfill prescribed by State regulations, based on the characteristics of
the waste.
Estimates of Waste Volumes
Table III-2 shows estimated liquid waste volumes for the 18
operational power generation facilities that use geothermal energy from a
liquid-dominated system. Of the estimated 56 billion gallons per year
(BGY), 62 percent are generated at flash process facilities, while
38 percent are generated at binary process facilities. If the estimated
production rates for the three facilities under construction are
included, the total waste volume increases to 71.63 BGY (see Appendix A).
42
-------
Because of the sparcity of the data, no attempt was made to quantify
the solid waste generated from power generation facilities. Several
facilities in California generate solids using a patented
clarification/thickening process during brine treatment (Morton 1986).
Based on a review of the literature, these facilities are the sole source
of any significant generation of solids.
WASTE GENERATION FROM DIRECT USERS
The primary waste generated from using geothermal energy as a direct
source of heat is the spent geothermal fluid remaining after usable heat
has been extracted. In most cases, this fluid is of high enough quality
to allow it to be discharged into nearby surface water bodies. In some
cases, spent geothermal fluids even meet drinking water standards and may
be discharged into the community water supply.
Waste generated by direct applications was calculated similarly to
waste quantities from power generation facilities. Industrial direct
users were estimated to operate about 80 percent of the year (292 days).
All other types of direct users were estimated to operate 25 percent of
the year (91 days), or less, depending on geographical location. By
multiplying daily flow rates by the operating factors, estimated waste
volumes were obtained. Table III-3 shows estimated liquid waste volumes
for 104 direct users in 12 States. These volumes were calculated as
described previously.
WASTE CHARACTERIZATION
The following paragraphs discuss the characteristics of waste
streams resulting from exploration, development, and production
operations, and present a summary of the analytical data found in the
literature for both liquid and solid wastes. These data are summarized
43
-------
Table III-3 Estimated Liquid Waste Volumes
Resulting from Direct Use of Geothermal Energy
Billions of
gallons per year
1.41
.60
3.02
.09
.78
.31
.15
.50
.61
.50
.01
.10
8.09
Source: See Appendix A.
State
Cal ifornia
Oregon
Idaho
Montana
South Dakota
Utah
Wyoming
New Mexico
Nevada
Colorado
New York
Washington
Total
Number of sites
18
14
27
7
4
4
3
8
10
6
1
_1
104
44
-------
in Tables III-4 through 111-13 and are compared to current RCRA
characteristic thresholds (ignitability, corrosivity, reactivity, and
extraction procedure toxicity) for both solid and liquid wastes.
Liquid Wastes
Tables III-4 and III-5 contain temperature, pH, and chemical
constituent analysis summaries for selected waste streams from geothermal
plants, power generation, and direct use of geothermal energy. These
tables were constructed from several references listed in Appendix A.
Table III-4 contains a chemical constituent liquid analysis summary
of liquids from seven different power generation facilities. Five of the
seven facilities produce power using the binary process. For these
facilities, the concentration levels of various constituents are shown
for the incoming brine, with the exception of temperature, which is the
measured discharge value. (The chemical abbreviations for these
constituents are shown in Appendix B.) Since no change occurs in the
physical state of the geothermal liquid in the binary process, these
results are expected to be representative of the discharged brine. This
assumption is not entirely valid, however, for power plants using the
flash process. In these plants, the various chemical constituents can be
concentrated in the liquid that remains after the progressive series of
steam generation steps.
Table III-5 reports analyses of geothermal fluids from 43 direct
users in 13 States. In general, the levels of chemical constituents are
much lower than for power plant brines.
Table III-6 contains chemical analyses of three brine samples tested
for both major and trace constituents. These samples were collected in
1980 from three test well sites in the Imperial Valley (Acurex 1980).
45
-------
cr>
1ABLE II 1-4 POWER PI ANT
LIQUID ANALYSIS SUMMARY
NAME
EAST MESA
EAST MESA
(b C MfCABE NO
HEbER
HfbER
SAL1GN SEA
(VULCAN)
WENDELL-AMfDEE
(WENDELL HOT SPR
SHAK&OAT SPRING
ST/COUNTY
TYPE TEMP
Or
pH
TDS
mg7L
Na
mg/L
K
mg/L
Ca Mg
mg/L mg/L
Cl
ALK SO.
mg/L mg/L mg/L mg/L
B
mg/L
sio2
mg/L
mg/L
I)
IN&S)
CA IMPERIAL LPB 71 0 9 00 1978 623 39 00 32 01 514 4 0 530 169 3.2 489.0 0 00
CA IMPERIAL LPB 71 0 7 40 16330 4720 231 00 1062 0 23 0 8242 1 5 202 148 80 187 0 0 00
CA IMPERIAL LPF 72 0 7 10 14100 3600 360 00 880 0 24 9000 1 6 20 1000 5.0 120 0 2.00
CA IMPERIAL LPB 72 0 7 10 14100 3600 360 00 880 0 24 9000 1 6 20 1000 5 0 120.0 2.00
CA IMPERIAL LPF 105 5 30 183700 36340 7820.00 14550 0 780 0 93650 00 60 58 210.0 350 0 0.00
CA LASSEN LPB 92 2 8 50 827 227 6.80 16 0 0 0 160 4 5 27 268 4.0 96.0 0.00
)
NV WASHGE LPB 69 2 7 90 2169 653 71 0 5000 865 1 8 305 100 49 0 293.0 4 70
KEY FOR POWER PLANT TYPE
First Letter Second Letter
Ihird Letter
L - Liquid P - Power Generating f - Flash Process
B - binary Process
Source- See Appendix A
-------
O/ 0
O/'O
O/ 0
00 0
00 0
00 0
06 Z
00 0
00 0
00 0
00 0
00 0
00 0
OO'O
00 0
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OO'O
00 0
00 0
19 I
65 I
Vfiu,
S?H
0 IS
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0 95
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0'/9
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5'9
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1/611
ZOIS
1 6
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ro
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6'0
O'Z
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El
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I/Bui
g
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OIE
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91
6E
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frfr
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0001
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ZSZ
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62
6
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99
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96
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59
965
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099E
591
06
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l/fbui
,-nv
\> L
fr /
6 E
\r 6
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O'S
9'E
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9 0
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fr'O
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9 91
V&m
J
091
091
5
6
fr
0/P
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frfr
000 II
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OH
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09
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z
t>El
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13
0 Zl
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O'frfr
O'OZZ
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0'09E
0 005
O'OtrZ
0 ZS
0 5
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0'9Z
0 OS
0 St>
0 tr
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1/6")
P-)
00 OZ
00 OZ
00 9Z
OZ I
OF. 'I
00 6Z
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09 I
09 8
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01 S
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0591
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I/BUI
PN
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OZZI
559
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0991
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566
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691
9t>fr
09E
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09 9
9fr 9
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09 9
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Ofr 9
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01 6
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701
sai
sai
r'31
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CO!
cai
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cai
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^ n i
oai
sai
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cai
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M3H9V3W 1W
M3H9V3W 1W
39001 a3ja iw
33HAno 01
51HATO 01
YOI3t;0 01
vissvo a i
•JOANV3 ai
vov a i
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013UMV9 03
V13l(W3aV 03
VISVhS V3
OdSiao
SI01 HVS V3
C'JIO«VNH3a
NVS V3
3ai:»3/\!M V3
M3C,SV1 V3
3>V1 V3
ONV1MV9 W
NOAOO XV
NOAOO XV
A1M003/1S
nnnns 31 inn
SONIOdS
MfUinS 31!Hrt
IVildSQH
31V1S SOMMdS HM^n
nv3nni)9
' .(NV9
A 113 ^0 1VW
OH IV
tljMU WD
A1I3 3S109
SOHIMdS IOH AVMflO
S9NIMdS OOCflN319
SON i yds vscsvd
S9t)IMdS iOH SIHflH
S3iaoa osvd
9NI1VJH 13IM1SIO
- ONIOMVH83g NVS
V113M9V03
3iiiMvsns
IOH jmqVND
-IHVa WNOI1VN
S'.HI^dS 1CH
'OHIbdS IOH AjINVI
SOUIHdS IOH tfNIHI
3MVJ
(31IS A9)
jiavwwns siSAiVNV oinoii
S«3Sn 133MIO 9-111 31W1
-------
TAbl E i ll-'j (cent inued)
KAMI
TYPE TF.MP pH TDS rid
L mg/i mg/L
LOLO
LAS ALTURA;.
APACHE TEJO AND
t EtlNElOTT WARM
SPRINGS
GILA HOT SPRINGS
- SPACE HTG £ POOL
TRUTH OR
CONSEQUENCES
CALICNTE - SPACE
HTG a POOL
CAL IE NT E - SPACE
HTG & POGL
MOAN; GFOIHERMAL
MGANA GEGTHERMAL
KLAKA1H FALLS
D1STRICI HEAIlliu
(INJECT)
n AM; TII I-AI L ,
CISIPK T ill A! l!<<.
(SURF)
n AMA1H f AL L'
PGOl
KLAKA1H FAi LS -
SPACE HEATING
(1NJECI)
KLAMATH FALL S -
SPACE HE A! ING
(SURI ]
MT
NM
NM
NM
NM
NV
NV
NV
NV
OR
OR
OR
OR
OR
MlSSOHlA
DONA ANA
GRAM
GRANI
SIERRA
1 IIICOLtt
LINCOiN
WASHOE
WASHOt
1- LAMA I H
I'LAfAlH
1 IAICIH
t LAMA1H
KLAHATH
ID:.
ID,
LD1
LDL
IDi
LD ,
LD.
IDQ
ID
IDS)
ID'J
LD^
ID.
ID-,
3?
45
27
41
51
58
64
9t
96
60
60
60
60
60
0
1
0
0
0
0
0
0
0
0
0
G
0
0
9
8
6
8
6
7
7
8
8
8
8
8
b
8
30 2?4
07 2160
43 370
13 468
70 2620
20 336
20 335
00 856
00 866
20 736
20 7 A
20 736
20 7J6
20 736
52
48«
48
13
742
39
39
199
199
195
195
195
195
195
1.20
55 00
4 60
3.00
17 60
14 00
14 00
3 70
3 70
3 90
3 90
3 90
3 90
3 90
1 6
142 0
34 0
9 9
57.0
34 0
34 0
21 0
21 0
24 0
24 0
24 0
24 0
24 0
0 1
32 0
17 0
0.1
18.8
4 6
4 b
4 1
4 1
0 1
0 1
0 1
0 1
0.1
K Ca Mg Cl F ALK S04 B SIO? H^S
mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L
664 86 18 0.1 72 0 0.50
WO 1 6 348 223 0.6 68 0 0 00
19 2 7 222 70 0.8 0 0 0.00
9 9 0.1 105 91 101 46 01 74 0 0 00
340 3.6 250 120 0.2 41 0 0 00
8 1 4 200 30 00 106.0 0 00
8 1 4 200 30 0.0 106 0 0 00
32 1.5 211 325 07 79 0 0.00
32 16 211 325 07 79.0 0 00
58 1 5 44 400 10 31 0 0.00
58 1 6 44 400 10 31 0 0 00
58 1 6 44 400 10 31 0 0 00
58 1
44 400 10 31 0 0.00
-------
TABLE 111-5 (cont inueci)
wo
KAMI
VAti
VAlE
COVE HOI SPRINGS
ST MAPY'S
HOUR 11 Al
NEWCASTLE
U1AH STATE Phi SON
SOI DUC HOI
SPRINGS-SPACE
hTj «, POOL
THERMOPOLIS
ST/COLINTY TYPE TEMP pH
°C
OR KALhtlJR ID1 66 0 fa 00
OR MALHEUR IDG 77 0 b 00
OR UNION LOG 24 0 8 57
SO HUGHES LDS 37 0 6 80
UT IRON LOG 41 0 7 60
LIT SALT LAKE LD-, 66 0 7 50
WA CLAILAH LDS 24 0 9 46
WY r,OI LOG 43 0 6 90
SPRINGS
First Letter
L - Liquid
V - Vapor
1 DS Ha K
mg/L mg/L mg/L
476 134 2 20
476 134 2 20
196 32 0 80
2084 60 21 00
1120 270 21 00
891 191 16 00
262 80 1 00
2190 250 37 00
KEY FOR DIRECT
Second Letter
D - Direct User
S - Space Heat ing
Co Mg Cl F ALK S04 B
mg/L mg/L mg/L mg/L mg/L mg/L mg/L
3005 4 1 6 192 121 03
30 06 4 16 0 192 121 0 3
2001 603 114 7 10
402 0 86 0 75 00 124 1445 1.6
58 0 0 4 52 7 3 53 580 0.7
76 0 25 0 226 0 6 264 191 0.4
0800 21 1 7 181 7 14
3)0 0 71 0 300 68 710 730 0 5
USFR TYPE
Third Letter
F - Fish Farm
G - Greenhouse
D - District Heating
1 - Industrial
P - Pool heating
S.O, H2S
mg/L mg/L
40 0 0 00
40 0 0 00
36 0 0.00
27 0 0 70
99 0 0.00
35 0 0 00
60 0 10 00
37 0 0.00
Source See Appendix A
-------
Table Ill-b Liquic Waste: Test Well Brine Analyses
Location- Imperial Valley
bite-
Owner
Bulk
Compos it ion (ing/' L)
A:
Ca
Fe
Mg
K.
Na
Cl
s
Trace Analysis (ug/L)
As
Ba
Cd
Cr
Pb
Hg
5e
Ag
Sb
6e
B
Cj
Ll
Ni
S r
Zn
pH
TOS (mg/i.)
Rad i L.m 225 (jC i s )
East Mesa
Repuol ic
Geotherina 1
Niland Westmoreland
1 B
30 0
0 97
1.7
91
1,500
1,700
10
13
65
310
^300
<5
<20
-20
<20
-70
, sOO
-200
-coe
.-0
S 7
56
0 0
Republ ic
Geo thermal
cl
51,000
3,200
313
3d, 000
55,000
295,000
19
300
<0.01
<0 1
<250
363,000
70
9«Q
NR
Int
<500
NR
-200
-20
560,000
7,400
NR
3CO
l.iOS.QOO
NR
1 5
5,500
0 4
MAPCO
1 2
14,800
2,100
440
10,000
60,000
158,700
10
la
-1
-0 1
14.000
22,000
4,000
<60
S3, 000
<1
5,100
-20
<• 1 , 000
<20
230,000
-100
240
<:oo
1,400,000
0,000.000
3 8
220
1,320
NR - Not Keportdt! (proprietary jata restriction)
Int • Interference (reporting of rcsu'ts not
50
-------
These test data can only be considered preliminary because the chemical
analyses have not been verified through further testing. The first eight
elements reported under the Trace Analysis columns are contaminants from
the RCRA extraction procedure (EP) toxicity test for determining whether
a waste is hazardous.
Table III-7 (Morris, et al. 1981) also contains chemical analyses
of brines from three wells, two of which are from the same sites as in
Table III-6. All test well fluid samples were taken from onsite pits or
tanks. Again, the first eight elements shown are the eight RCRA EP
toxicity contaminants.
Solid Wastes
The literature contains very little site-specific data relating to
the composition of solid wastes from geothermal operations. Two
references (Acurex 1980, 1983) discuss the analyses of 33 samples of
various solids and liquids collected in 1980. Again, these data can only
be considered preliminary at this time because the results have not been
verified or subjected to a quality assurance procedure. These samples-
were analyzed in considerable detail, including leachate analyses for EP
toxicity. Tables III-8 through 111-12 list analytical results for the 11
samples that are applicable to this study.
Tables III-8, III-9, and 111-10 list concentrations for major
constituents contained in the 11 samples. These constituents indicate
the composition of the sample. Results are reported for total
constituent content; neutral and acid extractable values; and pH, percent
moisture, and radium concentrations.
51
-------
Table III-7 Metals Detected in the Extracts of Geothermal Brines
Location-
Owner:
Well Designation:
Constituent fmq/L):
Imperial Valley
Imperial
Magmamax -1
Republ ic
Geothermal
Fee -1
(Niland)
MAPCO
Courier -1
(Westmoreland)
Ag
Asb
Ba
Cd
Cr
Pb
Se
B
Be
Cu
Li
Ni
Sb
Sr
Zn
Al
Ca
Co
Fe
K
Mg
Mn
Mo
Na
Rb
Si
Sn
Ti
V
.1
25.0
250.0
<5.0
<1.0
50.0
NA
600.0
<.2
5.0
130.0
<1.0
<5.0
400.0
200.0
<1.0
MC
<1.0
250.0
MC
100.0
400.0
<2.0
MC
10.0
300.0
<4.0
< 5
<4.0
.5
<5.0
400.0
<4.0
<1.0
200.0
NA
400.0
<.4
10.0
2000.0
5.0
<10.0
800.0
1000.0
10.0
MC
<1.0
1000.0
MC
400.0
800.0
<4.0
MC
25.0
30.0
<4.0
<10.0
<4.0
.1
20.0
1300.0
<3.0
<1.0
130.0
NA
130.0
<.3
<.7
1000.0
<3.0
<7.0
1750 0
400.0
70.0
MC
<1.0
550.0
MC
250.0
250.0
<3.0
MC
17 0
20.0
<4 0
<10.0
<4.0
MC - Major constituent, ranging from approximately 2,000 rag/L
to higher levels.
NA - Not applicable.
Determinations by optical emission spectroscopy.
Preconcentration using CuS carrier prior to spectographic
analysis.
Source. Morns 1981.
52
-------
lAblE 111-8 SOLID WASH bULK (.OMP'J',1 ! I OH
Si IE
D£:[«T PL At - NEVADA
HUMBCt T - NEVADA
IMPERiAl VALLEY -
M.-lf-'SRELANLl
IMPERIAL VALLEY -
ML MID
IMPERIAL VALLEY - EASI
Kill-
1H£ GEYSERS
The 'it tSER.,
STriKtOM - NEVADA
Go WfRIAL VALLEY - EAST
IMPERIAL VALLEY - EAST
MESA
IMPERIAL VALLEY - EAST
MESA
r f i Ff,K '.AMflt Typf
OWNER
CHEVRON
PHILLIPS
MAPCO
REPUBLIC GEO
REPUBLIC GEO
AMI NOIL USA
UNOCAL
PHILLIPS
DOE/WESTEC1
DOE /WE SI Ef
DGE/MA'jMA
SAMPLE
IYPE
MJD
MJD
MJD
MUD
MUD
MUD
MJD
MUD
faRIHE
SCALE
bRINE
TOTAL
/
Al
1 9H
2 02
2 10
2 57
1 20
2 45
1 58
1 63
0 22
0 29
0 01
TOTAL
y.
Ca
0 67
1 90
2 20
2 20
1 65
0 93
0 59
1 80
0 73
11 40
1 50
TOTAL
/
ft
2 95
2 35
1 60
1 70
0 66
3 90
3 03
1 85
0 32
5 10
2 45
10TAL
/
Mg
0 92
0 73
0 69
1 15
0 43
1 78
1 65
0 67
0 15
0 13
0 02
TOTAL
/
1
0 59
0.54
0 97
1 10
0 36
0 51
0 27
0 46
0 09
0 04
1.10
10TAL
'7
No
0 77
0 40
2 OC
1 25
0 24
0 09
0 11
0 19
0 09
0 11
4 30
TOTAL
/
Cl
0 98
C 10
5 30
2 00
0 10
0 01
0 01
0 04
0 09
0 06
9 30
TOTAL TOTAL TOTAL TOTAL
0
0
0
0
0
0
0
0
0
0
0
y
F SiO
024 27
034 20
029 42
042 29
023 24
018 45
024 19
015 21
010 3
040 9
340 12
/'. /
2 4
40 0 06
20 0 22
40 0 01
20 0 15
40 0 05
60 0 01
40 0 02
60 0 05
80 0 01
90 0 01
40 0 01
/.
5
<0 OOG2
< 02
' 2
' 02
< 1
< 0002
- 02
' 0002
< 0002
< 01
<• 01
PH
•9 10
9 80
8 80
8 40
12 00
9 60
10 00
9 30
8.80
8 60
6.10
V.
MOISTURE
9.90
36 00
31 00
62.00
60 00
23 00
53 00
34.00
34 00
61.00
46.00
RADIUM
226
pCl/G
1.50
1.60
5 90
2 10
1 00
0 40
0 50
1 00
3.80
3.00
78 00
MJD - Sample taken from drilling nuKi disposal pit
Ekllit - brine sample token from teut well
iCALE - Sample taker, from irbide iirine containment
vessel
Source See Appendix A
-------
TABU 111-!) UMIDWA.TE ACID EXTRACT 6UU COMPOSITION
(Units = mg/L)
DtSthl PEAK - NEVADA
HJMhOLT - NEVADA
IMPinlAL VALLEY -
W: STM3RELAND
IMt'tklAL VALLEY -
MIAN!)
IMPERIAL VALLEY - EASI
MlSA
THE fjEYSERS
ME bEYSERS
'.lEHl'ijOAT - NEVADA
IMPEnlAl VALLEY - EASI
MtSA
IMPERIAL VALLEY - EAST
MESA
IMPERIAL VALLEY - EAST
MESA
UWNI '*
I HE VON
Prill L IPS
MAPCO
ktPUb.IC GIO
REPUbLlC GfO
AM! NOIL USA
UNO; A>
PHiLLll'S
DOE /W: SUC
DOE/WESTEC
HOE/ MAGMA
CAMPLE
TYPE
MUD
MUD
MUD
MUD
MUD
MUD
MUD
MUD
BRINE
SCALE
BRINE ,
Al Ca
-------
•'•''5
t > 99 291 QtK 0061
[ > 2 9 0 fr Zfr 69 09
T> 99 9 fri 89 09
I > 22 El 9* 22 Of
I ' 29 91 «2 I> 9>
t > tM fr H 1 92
I OE f 2E 99 901
I > Oil fr> 99 0911 099
I'> i 9 t> t?2 0222 096
I > fli 6 19 E9 021
I 0> Ofr fr> IE 26fr Oil
oot-
£ 9
II
21
9 I
"'
81
021
091
i tr
02
/ E 2 -
SO 2 -
at? 2 >
90 2 >
frO • 2 >
Cf P
,0 2
9 2 >
9 20 >
t> 26
99 I
Ot-B l>
2 E I>
fr 9 I>
I 9 I-
fE I-
18 l>
82 2 1
021 I>
OEE I •
92 9 f
ft? I>
3NIH9
31V39
3NIHQ
OI1W
onw
onw
.onw
onw
onw
onw
onw
WJtfd.'JOO !^V1 A313VA
V^3W
DH^n/lOO HV3 - A j IT/A IVIHJdWI
V. 3H
SWIOa ISV3 - A331VA
039
S.JI 1
>8r>A39 JHJ
SMISAIO wi
A311VA
A311VA WIHJuWI
- A311VA
VQVA3N -
VGVA3H - Vv'd I SI'-, 30
10
usvn (iMor; oi-m
-------
Tables III-ll and 111-12 list 16 trace constituent concentrations
for the same 11 samples. Eight of these constituents are EP toxicity
contaminants. In addition to analyses for the eight EP toxicity
contaminants, tests were also conducted for eight other metals. These
metals (antimony, boron, beryllium, copper, lithium, nickel, strontium,
zinc) were included because they are listed in the water quality
standards of several western States. Analytical results for these metals
are summarized in Table 111-13. In general, the measured concentrations
of these metals are fairly low, except for those of boron and zinc.
One other study (Morris 1981) provided analyses of a similar group
of samples, with both major and trace elements. The results are
presented in Tables III-ll and 111-12 and are based on the acid extracts
from the six solids samples. Four of the samples are from various
drilling mud pits; the remainder are from the GLEF test facility. Two of
the drilling mud samples are the same as those shown in Tables III-8,
III-9, and 111-10.
Analysis of Waste Constituents
Some of the exempt geothermal wastes characterized in the previous
sections failed the EP characteristics test and could be considered
hazardous wastes. The hazardous characteristics present include
corrosivity and EP toxicity for certain metals.
The corrosive characteristic applies to wastes with pH values equal
to or less than 2.0, or greater than or equal to 12.5. Maximum
concentration levels for EP toxicity metal contaminants are as follows:
56
-------
TABLE 111-11 SOLID WA.-JE AC.ID UIKCl IkACE ANALYSIS
(Units = parts per million)
DESERT PEAK NEVADA
HUMbOLT - NEVADA
IMPERIAL VALlEY -
WE:TMGRELAN[)
IMPERIAL VAUEY
III: ADD
IMPERIAL VAUEY - EAST
MESA
THE GEYiERS
TH£ GEY.ERS
STEAMBOAT - NEVADA
IMPERIAL VALLEY - EAST
MESA
IMPERIAL VAi LEY - EAST
MESA
IMPERIAL VAiLEr - EAST
ME,A
OWNER
CHE VRGfs
PHILLIPS
MAPCO
REPUBL 1C GEO
REPUBL 1C GEO
AM ING U USA
UNOCAL
PHILLIP:.
DOE /WE v- TEC
UOE/WESTEC
DOE /MAGMA
SAMPl E
TYPE
MUD
MUD
MUD
MUD
MUD
MUD
MUD
MUD
bRINE
SCALE
BklHE
As Bd Cr
•20 bOO 6
49 13000 2(
63 1800 6
'20 1400 '
•20 1400 '
•20 '300 '
60 600 '
45 3800 «
36 10500 '
230 5000 6C
J Cr
J '20
-20
'20
70
'20
'20
'20
'20
'20
Pr, Hcj
400 '1
60 --]
-20 ->
30 '1
20 'i
•20 -1
'20 '1
'20 -1
'20 < 1
200 '1
Se
30
'20
100
30
'20
'20
'20
'20
'20
'20
160
Ag
'20
'20
'20
'20
'20
'20
'20
'20
'20
'20
'20
Sh
'50
<50
'50
'50
'50
<50
'50
'50
'50
180
'50
Be
'20
'20
'20
'20
'20
•20
•23
'20
'20
<20
'20
B
/"Ti
C J\J
'200
250
'2000
'2000
'200
870
300
'2000
'200
12000
Cu
200
<70
<70
-70
'70
'70
'70
'70
'70
150
150
Li
300
50
3300
1300
'50
'50
<50
500
170
220
5800
Ni
'300
'200
<200
<200
<500
300
<300
<200
'200
500
Sr
2600
3000
23000
5400
2200
3500
600
1000
8300
'500
12000
Zn
140
420
7000
1300
150
80
300
120
110
70
6400
Source See Appendix A
-------
lAbLt 111-12 SOLID WASTE NEUIRAL EXTRAU TRACE ANALYSIS
(Units = parts per million)
oo
:ITE
DESERl PEA* - NEVADA
hUMEOlT NEVADA
IMPERIAL VALiEY -
WES!MORE LAND
IMPERIAL VALLEY -
MLAND
IMPERIAL VALLEY - EAST
MESA
THE GEYSERS
THE GEYiERS
STEAMBOAT - NEVADA
IMPERIAL VALLEY - EAST
MESA
IMPERIAL VALLEY - EAST
MtSA
IMPERIAL VALifY - EAST
MtSA
OWNER
CHEVRON
HULK'S
MAPCG
REPUBLIC GEO
pr pijh) 1 1 fiFf)
n L r UUL 1 1_ OCU
AMI NOIL LbA
UNOCAi
PHILl IPS
DOE/WESTEC
DOE /WE SI EC
DOE /MAGMA
SAMPLE
1YPE
MUD
MUD
MUD
MUD
MI in
nuu
MUD
MUD
MUD
BRINE
SCALE
BRINE
As
'20
140
11
•20
t')(\
^- C \i
20
32
260
65
33
230
fca Cd
<300 ^
500 5
6aOO '5
'300 «5
<"3on n
'20
'20
<20
<20
<20
Se Ag SE) Be B Cu Li Ni Sr Zn
) '20 470 100 200 '300 '500 50
) «20 -200 100 <50 <300 <500 2dO
20 1100 70 3100 <200 20000 '20
3 '20 200 <70 1100 <200 1500 <20
J '20 '200 <70 '50 '200 <500 <20
] '20 '200 <70 <50 <500 '500 '20
] -20 15000 <70 '50 500 <500 '20
20 '20 70 '20 570 '70 400 <300 <500 <20
<50 <20 '200 '70 130 <200 <500 <20
180 '20 '200 70 140 <200 '500 <20
<50 '20 13000 <70 7900 '200 15000 4000
.ourcc See Appendix A
-------
Facie 111-13 Metals Detected in the Extracts of Geothermal Solid
Wastes from the Imperial Valley Area3
Owner-
Well desiqnat
Constituent (
Ag
AsC
Ba
Cd
Cr
Hgc
Pb
Sec
B
Be
Cu
L;
Ni
bb
Sr
Zn
Al
Ca
Co
^e
k
Mg
Mn
Mo
Na
Rb
5 :
Sn
Ti
V
Occidenta 1
ion. Fed Lease
•na.'L) •
< 01
< 50
30
< 10
< 02
<1.0
< 1
< 5
02
«• 003
< 02
02
5
•• i
1 0
< 1
05
MC
< C3
2 0
5 0
10 0
4
-- 03
MC
* 1
5 0
< 1
< l
<- i
Occ identa 1
Neasnam Republic
< 01
< 5
5
< 1
<• 01
<1 0
- 1
<- 5
1
- 003
02
04
1
- 1
2 0
< 1
6
MC
«. 03
2 0
4C 0
10 0
1 3
< 03
MC
15
30 0
<• 1
•- i
^ i
< 01
•=1 0
3 0
•^ I
< 03
<1 0
06
<• 5
2 0
< 01
01
3 0
1
•• 2
10 3
5
2
MC
* 03
1 0
MC
10 0
4 0
1
MC
1 0
10 0
^ I
< 3
< 1
MAPCO
Fee-1
- 01
<1 0
25 0
* 1
< 03
*1 0
1
< 5
5 0
- 01
03
10 0
2
- 3
25 0
15 0
1
MC
- 03
1 0
MC
15 0
10 0
< 1
MC
2 0
3 0
- 1
^ 3
^ i
GLEFd
Courier
01
< 5
3 5
^ 1
< 02
-1.0
7.0
Int.
4 0
- 007
7
15 0
07
- 2
5 0
5
07
MC
< 02
^
MC
2 0
5 0
< 1
MC
I 0
2 0
^ i
- 1
,. ;
02
-- 5
7 0
< 2
< 04
<1.0
.07
Int.
7.0
< 01
1 0
30 0
< 02
•- 4
13 0
7
1
MC
< 04
v 4
MC
3 0
10 0
< 1
MC
1 0
4 0
Int = Interference.
MC = Mdjcr constituent, ranging from approximately 5,000 mg/L to h'gner levels
dOetermindt ions by optical emission spectroscopy , except as noted.
'Values '-pprecent mean of five samples analyzed
^As, Hg, cinj be «ere determined By atomic aosorption spect rophotomet i-y Interference
on Hg precludes lower Jetecti on level of rig
'"it'Othernu 1 Loco Experimental ".icilrty
Source Morris 19ol
59
-------
Maximum concentration
Metal contaminant (mg/L)
Arsenic 5.0
Barium 100.0
Cadmium 1.0
Chromium 5.0
Lead 5.0
Mercury 0.2
Selenium 1.0
Silver 5.0
Two of the three brine samples, characterized in Table III-6, exceed
allowable levels of RCRA hazardous characteristics. The sample from the
Niland site exhibits the corrosivity characteristic, with a pH of 1.6,
and also exceeds the EP toxicity concentration for barium. The brine
sample from the Westmoreland site exceeds the EP toxicity limits for the
following four metals: arsenic, cadmium, lead, and selenium. Similarly,
the three geothermal brine samples characterized in Table III-7 also
exceed allowable contaminant concentrations for arsenic, barium, and lead.
Sufficient constituent data are not available to further evaluate
the other waste streams with respect to the EP toxicity contaminant
concentrations.
DISCUSSION OF DATA ADEQUACY
Sufficient data are not available to accurately characterize or
precisely quantify the volumes of wastes generated from power production
and drilling activities related to geothermal operations. Waste
information available in the literature applies only to a few
site-specific cases. Since the characteristics of geothermal wastes
relate directly to the geology and mineralogy of a resource area,
additional site-specific data are required to more fully characterize
geothermal industry wastes.
60
-------
The available historical data are insufficient to project future
total volumes of drilling mud and cuttings expected to be generated by
the geothermal industry. To predict future waste disposal requirements
and associated potential problems, an accurate historical record must be
established, from which to extrapolate. The types of data needed are not
generally published in the literature, and industry cooperation is
essential. Information must be obtained concerning volume,
characteristics, and chemical constituents of mud pit solids, drill
cuttings, and injected fluids.
61
-------
CHAPTER IV
WASTE MANAGEMENT PRACTICES
This chapter describes current and alternative waste disposal
practices for wastes generated from geothermal exploration, development,
and production operations. An economic analysis and cost comparison of
current and alternative practices is also included.
CURRENT WASTE MANAGEMENT PRACTICES
The following discussions pertain to waste management techniques
practiced during geothermal drilling, power production, and direct
applications.
Waste Management Practices for Waste Products from Drilling Operations
The primary wastes from both geothermal and petroleum industry
drilling activities are drilling muds and drill cuttings. Methods
currently practiced by the geothermal industry for handling and disposal
of these materials have generally been developed by the petroleum
industry.
A review of the literature revealed only two references that
addressed the handling and disposal of wastes from geothermal drilling
activities. In both cases the wastes are discharged into a reserve pit.
At Heber, in Imperial Valley, California, drilling wastes are discharged
into a reserve pit, from which the wastes are collected for offsite
disposal (USDOE 1980b).
63
-------
One reference (Royce 1985) describes the drilling-waste handling and
disposal methods used at The Geysers. These waste management methods
reflect current regulatory policies in California. At The Geysers, an
onsite reserve pit is constructed with a two-foot-thick clay liner,
having a permeability of less than 10 cm/s. Wastes remaining in the
pit are tested by the RCRA characteristic test to determine if they are
nonhazardous. Wastes that are determined to be hazardous are transported
to approved hazardous waste disposal sites. For more details on waste
toxicity testing and approved waste disposal facilities, see the Summary
of California's Geothermal Regulations in Chapter VII. (Please note that
California may consider some of the exempt wastes hazardous under its
State regulations, even though they are exempt.)
After the solids settle and the liquid is pumped off for well
injection, the reserve pit is capped. Reserve pit dewatering consists
merely of allowing any remaining liquids to evaporate from its surface
before backfilling. A more complex technology involves the use of alum
and polymers as flocculants to induce settling. After separation of the
liquid and solids, the liquid is discharged and the thickened solids are
covered with backfill. Associated with this method, however, is the
possibility that future contamination could result from the leachate
waste sludge that remains buried at the site (Hansen, et al. undated).
Landfarming is another reserve pit disposal option. This method
involves the mechanical distribution and mixing of reserve pit waste into
soils in the vicinity of the drill site (Fairchild 1985; Hansen, et al.
undated). In the petroleum industry, this method of disposal is
controversial because of the high chloride content of drilling wastes in
some geographical locations (Tucker 1985; Hansen, et al. undated). In
California, offsite waste disposal is used to dispose of hazardous wastes
(i.e., the State of California's definition of hazardous waste) from
64
-------
geothermal drilling. Instead of being removed by vacuum truck, however,
the reserve pit contents are allowed to desiccate, and the solids are
transported to an approved disposal site.
Stringent permitting requirements and State prohibitions limit
downhole disposal of drilling wastes (Hansen, et al. undated). This
method is not particularly effective for geothermal drilling operations,
and might actually have an adverse effect on the development of the
geothermal well.
Solidification of reserve pit wastes may be economically more
attractive than backfilling them. Solidification methods typically
involve mixing fly ash or kiln dust with the reserve pit wastes to
decrease the overall moisture content of the wastes and to stabilize the
mixture (Hansen, et al. undated). One reference (Hansen, et al. undated)
stated that problems associated with solidification include the potential
for leaching toxic metals, organics, and nonmetallics (particularly
chlorides) into ground water, or the possible bioaccumulation of these
constituents in plants and the food chain.
After completion or abandonment of a well, drilling mud and cuttings
remain in the reserve mud pit. The following quote from Rafferty (1985)
is offered to provide some perspective on the nature of the reserve pit.
"In the early days of drilling, the reserve pit was used to remove
drilled solids and store the active mud system. As more advanced
solids control and drilling fluid technology became available to the
oil and gas industry, mud tanks began replacing the reserve pit as
the storage and processing area for the active mud system. Today's
reserve pit is little more than an oversized collection point for
drill site waste, wellbore cuttings, and rainwater."
Fairchild (1985) lists the following five methods for handling
reserve pit contents:
65
-------
• Dewatering pit wastes, with subsequent backfilling;
• Landfarming the wastes into surrounding soils;
• Removing the waste with a vacuum truck and hauling it to an
offsite pit;
• Pumping the waste down the well annul us; and
• Chemical solidification of the wastes.
Waste Management Practices for Power Generation Facilities
Seven types of liquid waste disposal have been described in the
literature for power generation facilities:
1. Direct release to surface waters;
2. Treatment and release to surface waters;
3. Closed-cycle ponding and evaporation;
4. Injection into a producing horizon;
5. Injection into a nonproducing horizon;
6. Treatment and injection; and
7. Consumptive secondary use.
An international review of waste disposal methods showed potential
applications for each of these methods depending on the legal, technical,
and environmental aspects of the different power generation sites
(USDOE 1980a). At least four of the above-mentioned disposal methods are
being practiced or will be implemented at the 21 geothermal power
generation facilities that are currently operational or under
construction. Data on these four disposal methods are summarized in
Table IV-1. A brief description of the seven methods follows, along with
a discussion of the sites where each type is practiced.
66
-------
Direct Release to Surface Waters
Direct release to surface waters is the simplest disposal method.
This approach consists of discharging spent fluid to local drainage
systems. While this method has previously been practiced at all power
generation facilities (USDOE 1980a), current environmental constraints
have made it almost nonexistent for facilities in the United States. One
small binary facility (Wendell-Amedee, Wendell Hot Springs) has been
identified as discharging waste liquids to surface waters (California
Division of Oil and Gas 1985). This situation is justified because of
the high quality of the brine, as is indicated in Table III-4.
Treatment and release to surface waters can be a relatively simple
process. It can become costly, however, depending on the type of
treatment required. Treatment can vary from simply settling and
flocculating the waste fluids, to sophisticated physical/chemical
processes (USDOE 1980a). In this study, no power facilities were
identified as using this type of brine treatment.
Closed-Cycle Ponding
Closed-cycle ponding and evaporation consists of cycling the spent
brine through one or a series of ponds where salts can settle out and the
liquid can evaporate. Ponds can be either natural or manmade. While no
power generation facilities in the U.S. currently use this method, it
could be applicable in areas where the climate is arid and land is
relatively inexpensive (USDOE 1980a).
Injection of Liquid Wastes
Injection of liquid wastes into the producing horizon consists of
recycling the spent brine back into the same geothermal reservoir at a
67
-------
TABLE IV-1 WASIE DISPOSAL PRACTICES
FOR GEOTHCRHAL POWER GENERATION FACILITIES
NAME
ST/COUNTY
en
oo
NI LAND
EAST MESA
EAST MESA (B C MCCABE HO 1)
HEBER
HEBER
SALTON SEA
SALTON SEA (VULCAN)
COSO
WENDELL-AMEDEE (HONEY LAKE)
WENDELL-AMEDEE
(WENDELL HOT SPRINGS)
MONO-LONG VALLEY (CAS DIABLO)
PUNA NO 1
LIGHTING DOCK
BRADY HAZEN
FISH LAKE
BEOUAWE
WABUSKA HOT SPRINGS
DESERT PEAK
STEAMBOAT SPRINGS
COVE FORT-SULFERDAIE
ROOSEVELT HOT SPRINGS
- MILFORD
CA IMPERIAL
CA IMPERIAL
CA IMPERIAL
CA IMPERIAL
CA IMPERIAL
CA IMPERIAL
CA IMPERIAL
CA INYO
CA LASSEN
CA LASSEN
CA MONO
HI HAWAII
NM HIDALGO
NV CHURCHILL
NV ESMERALDA
NV LANDER/EUREKA
NV LYON
NV RENO
NV WASHOE
UT BEAVER
UT BEAVER
DIRECT
RELEASE
SURFACE
dATER
X
INJECTION TREATMENT
INTO AND
PRODUCING INJECTION
HOk I ZON
X
X
X
X X
X
X X
X X
X
X
X
X
X
X
X
X
X
X
X
X
CONSUMPTIVE
SECONDARY
USE
X
X
X
Source. See Appendix A
-------
different location. These injection wells are considered Class V under
the Federal UIC program. Injection of spent fluids back into the
producing horizon is not only an important waste disposal practice, but
also is necessary for maintaining reservoir fluid volume. This process
has to be carefully planned to ensure injection into a zone that is
sufficiently permeable to handle large volumes of liquid. Brine
chemistry must be controlled to prevent plugging of the injection well or
reservoir. Also, the injection well should be far enough away from the
production well to prevent cooling of the production brine. Even with
such constraints, 22 power generators practice this method of disposal.
This is the most frequently used liquid waste management practice for
U.S. power generation facilities.
Injection into a Nonproducing Zone
Injection into a nonproducing horizon is identical to the management
practice previously mentioned, except the injection well is drilled to a
zone that is separated from the production well (USDOE 1980a). This is
primarily done in regions where the production zone is fractured and can
be easily contaminated by the cooler injection fluid. Injection into a
nonproducing zone has been tested at only one location. Tests of
injection into a nonproducing horizon at the Roosevelt Hot Springs flash
facility in Utah proved successful in 1980 (USDOE 1980a).
Treatment and Injection
Treatment and injection is used either where the brine quality is so
poor that the potential for plugging is high, or where a usable byproduct
could be recovered from brine before injection. Several examples of
pretreatment to prevent plugging are currently operational in the United
States. The Salton Sea flash facilities in the Imperial Valley operate a
69
-------
crystallizer/clarifier processing arrangement for silica removal prior to
injection (Royce 1985). Unocal uses this same process and is
investigating the conversion of the silica solids waste product into a
commercial product (Morton 1986).
Consumptive Secondary Use
Consumptive secondary use of liquid wastes is an effective waste
disposal method when the spent fluid can be reused as part of the power
generation process or by some adjacent facility. Six of the facilities
shown in Table IV-1 reuse condensate or clarified brine as makeup water
to the cooling towers. The Wabuska Hot Spring facility in Nevada
discharges warm water to a neighboring fish farm, where the water passes
through a series of fish ponds and is then discharged to other surface
waters (Lienau 1986).
The solid wastes can be managed by either onsite or offsite
disposal. In some instances, a combination of both alternatives is
used. Some facilities use brine holding ponds to accumulate solids.
Once these ponds are full, the material is excavated and hauled to a
landfill, in much the same way as desiccated drilling mud. Some
facilities, such as Unocal, produce a solid material that is filtered and
then hauled to a California Class I, II, or III landfill, depending on
the results of the toxicity tests with regard to RCRA characteristics
(Morton 1986). Small quantities of waste generated, such as scale, are
collected in 35-gallon drums onsite and then hauled to the appropriate
disposal facility (Morton 1986).
70
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Waste Management Practices for Direct Users
The seven methods of liquid waste disposal for power generation
facilities are applicable to, but not necessarily required by, the direct
users. Table IV-2 presents the waste disposal status for 104 direct
users in 12 States. Both the closed-cycle ponding and the treatment and
injection waste management options have been excluded from the table
because no facilities using these methods have been identified. For each
of the five methods shown in the table, at least one example of the waste
disposal practice has been found in the literature.
Direct release to surface waters is by far the most common method of
liquid disposal for direct users; of the 104 direct users listed, 90
discharge their wastewater directly to surface waters. This practice is
justified because of the low flow rates and the high quality of the
geothermal fluid being discharged. Some States (e.g., Oregon) have begun
to encourage direct users to switch to injection because aquifer levels
have seriously dropped in some areas.
Injection into the producing horizon is the next most common method
of disposal. Fourteen sites are currently listed as using this method,
with an increase expected in the future.
Consumptive secondary use is practiced at two facilities (White
Sulfur Springs, Montana, and Newcastle, Utah). Both facilities discharge
into holding basins where the water is collected for irrigation.
ALTERNATIVE WASTE MANAGEMENT PRACTICES
Although several refinements to existing processes have been
mentioned in the literature, very little information is available on new
disposal methods. This relative lack of research studies on alternative
71
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1ABIE IV 'e WASTE DISPOSAL PRACTICES FOR DIRECT USERS
NAME
SJSANVILIE
SJSAIWiUE
SUSANVILLt - NURSEY
WL UDELL-AMEDEE
CEDARVILI E HIGH SCHOOL
ELEMENTARY SCHOOL
FORT BiDWaL
FORT BIDWiLL - DISTRICT
HEATING
FORT B1DWELL - FISH
MAMMOTH LAKES - DISTRICT
HEATING
MAMMOTH LAKES - FISH
INDIAN VAuLEY HOT SPRING-,
(GREENVILLE)
COAtHELLA
FlSlN'jRf -101 SPRING'
MECCA
SAN bERNADINO - DISTRICT
HEAT ING
SAN BERNADINO - INDUSTRIAL
PASO RObaS
fcOULDER - GREENHOUSE
SAL I DA
ALAMOSA
SI /COuMY
CA LASSEH
CA LASSEH
CA LASSEH
CA uASSEN
CA MODOC
CA M'JDOC
CA MODOC
CA MODOC
CA MONO
CA MONO
CA PL DMAS
CA RIVERSIDE
CA RIVERSIDE
CA RIVERSIDE
CA .AN BERNADINO
bRINE
FtOW
RATE
(MuY)
61
12S
39
78
16
31
4
39
226
9
37
212
ti
326
e?
DIREi
RELE,
SURF,
WAIEI
X
X
X
X
X
X
X
X
X
X
X
X
X
CA SAN BERNADINO 73
CA SAN LUIS OBISPO 9
CO 41
CO 10
CO AlAMOSA 131
DISPOSAL METHOD
TREATMENT INJECTION INJECTION CONSUMPTIVE
RELEAiE INTO NONPRODUCING SECONDARY
SURFACE PRODUCING HORIZON USE
WATER HORIZON
-------
TABtE 1V-2 (continued)
CJ
NAMI
PAGOSA SPRINGS
uENWOOD SPRINGS
OtIRAY HOT SPRINGS
KJiSE CMY
BOISE WARM SPRINGS
HUNT
IDAHO S'ATE CAPITAL MAIL
THE EDWARD'S GREENHOUSE
VETERANS ADMINISTRATION
MEDICAL CENTER
DGMAY RANCH HOT SPRINGS
GARDEN VALitY
HOT SPRINGS
CAtDWELl
NAMPA
HOOPER SPRINGS
A; MO
b.ifl I Y
SCROOC 'S hREf MIOLhl
M^LAD CITY
tANfS
tPUNEAU
HOT SPRINGS
MAR SING
BIIHl
bUHL
ST/ COUNTY
CO ARCHULETA
CO GARFIELD
CO OURAY
ID ADA
ID ADA
:D ADA
ID ADA
IIJ ADA
!D ADA
ID bOISE
ID POISE
ID CAMAS
ID CANYON
ID f AN YON
iD CARIBOU
ID (ASM A
ID CASSIA
ID CASSIA
I D ONE 1 DA
ID OWYHEE
10 OWYHFE
ID OWYHEE
ID OWYHEE
ID TWIN FAILS
ID (WIN FALLS
BRINE
FLOW
RATE
(MSY)
l',7
167
6
?62
188
32
13!
S3
39
Q
39
4
184
9C,
32
2b
12
1
499
17
38
49
9
3
OH
DlKEI
REtEy
ShRFi
WATEI
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
DISPOSAL METHOD
T TREATMENT INJECTION INJECTION CONSUMPTIVE
iSt RELEASE INTO NGNPRODLIC ING SECONDARY
,CE SURFACE PRODUCING HORIZON USE
WATER HORIZON
-------
TABLE
NiMI
ST/COUUTY
fcuHL CAi fLINT
BUHL - rtlf.T
BuHL MfcL
fctHl - RAV
TWIN FALLS
WAr'M SPRINGS STATE HOSPITAL
FMCS
W-II It Sill F OH SPRINSS
WHITE Sill FUR SPRINGS
A vuN
I Oi 0
JAM1S SPRINGS
LAS AiIURAi
LAS CRUCIS SPACE HTG &
GRlENHOUSt
APl'ACH! IE JO AfJD rENNECOIl
WARM -.f-PINii
LlLA HOT SPRINGS - SPACE
HIG fc POO.
AM MAS
AM MA:
AM MAS
TR.iTH OR CONSEQUENCES
RENO
NM G^MJl
NM GRANT
NM HIDALGO
NM HIDALGO
NM HIDALGO
NM SIERRA
NV
DISPOSAL METHOD
8R1NE DIREC1 TREATMENT INJECTION INJECTION CONSUMPTIVE
FlOW RELEASE RELEA-E INTO NONPROUUCING SECOHDAPY
RATE SURFACE SURFACE PRODUCING HORIZON USE
(M'iY) WATER WATER HORIZON
ID IWIIJ FALI L
ID TWIN FALIS
ID TWIN TALL',
IE) TWIN FALLS
ID TWIN FAILS
MT DFER LODGE
MT MADISON
Ml MADISON
MT MtAGHER
MT MtAGHER
Mi MISSOULA
Ml I11SSOULA
NM
NM DOHA ANA
NM DONA ANA
43
80
1 01
11 60
1 73
9
4
3
9
5H
2
12
4
0
60
X
X
X
X
X
X
X
X
X
X
X
X
X
20
94
10
3
C
72
-------
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75
-------
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X
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-------
disposal methods may be due to an absence of damage cases resulting from
geothermal wastes and to the relatively small volume of RCRA-exempt waste
that is not injected into a subsurface reservoir. If these conditions
should change, requiring the development of alternative disposal methods,
similar, but more stringent, methods would probably be used. For
example, liquid wastes now injected into a Class V well would most likely
be injected into a Class II well, and solids that are disposed of by
onsite burial would probably be sent to an offsite, permitted facility or
an upgraded onsite facility (see Table IV-3). California currently
regulates these injection wells in a manner similar to Class II wells.
The California Division of Oil and Gas prefers this alternative because
geothermal operations and oil and gas operations are similar.
Landfarming may be another alternative. If, at some future date, it
appears necessary to restrict land disposal of solid wastes, then
solidification might become an acceptable option.
As new geothermal resources are developed, the chemical constituents
of the fluids may vary considerably. Such chemical variation could lead
to the discovery of new constituent recovery operations.
A new liquid waste disposal practice, developed by Aquatech
Services, Inc., consists of a proprietary evaporation process for
disposal of spent brines. However, this practice is better suited to the
oil and gas industry. The stated evaporation capacities of 16,800 gallons
per day are much less than normal power plant flow rates; however, there
are some small direct users for which this rate is applicable. Since the
process is viewed as competitive with injection costs, it could be
applied in some direct use operations.
77
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Table IV-3 Waste Manaaement Practices
Current Practices
Alternative Practices
Liquid Wastes-
Injection into Class V
injection wel1
Injection into Class II well, or
surface impoundment with double liner
Solid nonhazardous wastes:
Onsite burial
Solid designated wastes:
Onsite burial in 1ined
pit, or disposal in offsite
permitted faci 1 ity
Solid hazardous wastes
Onsite burial in clay cell,
or disposal in permitted
offsite Class I facility
Offsite disposal in permitted
Class II or III waste management unit
Landfarm or offsite disposal
in Class I permitted waste
management unit or solidification
Solidification
Class V injection well -
Federal Underground Injection Control
(UIC) Program classification for
geothermal injection well
Class 11 inject ion we)1 -
Class I waste management
unit
Class II waste management
unit
Class III «aste management
unit
Injection well usea to dispose of
nonhazardous fluids, generally brines
associated with oil and gas production
Most secure, double-lined landfill, surface
impoundment, or waste pile, RCRA-approved
fac 11 ity
Landfill, or surface impoundment class
designed for "designated wastes", commonly
used for drilling muds, fluids, cuttings,
sump so 1 ids.
Onsite or offsite landfill for nonnazardous,
nondesignated wastes
78
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In the event that the current exemption were lifted for one or more
waste categories, such wastes, if hazardous, would become subject to RCRA
Subtitle C procedures and requirements. Any facility handling any such
newly-defined hazardous waste would be required to comply with all
applicable minimum technological requirements, as well as permitting
conditions for ground-water monitoring, closure and post-closure
requirements, and, where necessary, corrective action. These newly
defined wastes would also become subject to review under the land
disposal restrictions program. This could lead to further restrictions
on allowable waste management practices.
It is not possible, in advance of these formal reviews, to
anticipate which "best demonstrated available technologies" (BOAT) would
eventually be required under Subtitle C to manage any hazardous oil and
gas wastes. Therefore, for the purposes of this report, the Agency has
estimated the potential costs of increased control by assuming compliance
with existing Subtitle C performance standards. It has also estimated
the costs of stabilization of drilling wastes.
In addition to the ground-water monitoring requirements that are a
mandatory part of standard Subtitle C permit conditions, the technologies
selected to represent potential additional costs of waste management
under Subtitle C include:
For drill ing fluids: disposal using a synthetic composite
liner with leachate collection and site management processes
consistent with Subtitle C, a landfarming facility employing
Subtitle C site management practices, a hazardous waste
incinerator, or stabilization of drilling wastes.
For geothermal fluid waste: the use of Class I disposal wells
as defined under the Underground Injection Control Program.
79
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ECONOMIC ANALYSIS OF WASTE MANAGEMENT PRACTICES
The geothermal industry is not pursuing alternatives to current waste
disposal practices, possibly because wastes from geothermal operations
are relatively small in volume (see Table III-l) and have caused no
documented environmental damage. Thus, a comparison of the costs and
economic impacts of current and alternative practices would be
problematic. Nevertheless, some available cost data are presented herein
and the gross cost impacts of the most likely alternative practices are
calculated. This brief analysis is limited to residual drilling wastes.
Cost Estimation Methodology
Published cost data in the literature were not only out of date
(1975-1978), but were primarily rough estimates of waste disposal costs
rather than actual costs. Also, most publications dealing with the cost
of geothermal waste disposal used one article published in 1979 as the
basis for their discussions.
For these reasons, cost estimates for alternative waste management
methods for drilling wastes are adapted from Volume 1 of this report. In
this report, surface impoundment costs for four different scenarios are
developed. They are: a one-quarter acre, onsite, unlined pit; a
one-quarter acre, onsite, single-lined pit; a 15-acre, offsite,
single-lined pit; and a 15-acre, offsite, triple-lined pit. The
annualized, per barrel costs for these options are presented in
Table IV-4. These annualized costs include a seven cent per barrel cost
for monitoring the single-lined, 15-acre facility and a two cent per
barrel cost for monitoring the triple-lined, 15-acre facility.
80
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These estimates are national averages, although the costs for EPA
Region IX, which includes California, are the same or slightly less.
These estimates do not include transportation costs, which would be site
specific and would depend upon the distance traveled. Volume 1 of this
report estimates the cost for transporting nonhazardous drilling muds at
approximately two cents per barrel-mile.
As documented in the Oil and Gas Report to Congress, comparable
costs to those in Table IV-4 for more advanced waste management methods
for drilling wastes are as follows: The costs for solidification range
from $3.00 to $10.00 per barrel, with the average estimated to be
approximately $6.00 per barrel. The annualized cost for landfarming in
California ranges from $16 per barrel for a pre-interim status facility
to about $38 per barrel for a facility complying completely with RCRA
requirements. These differences stem from the elaborate site management,
monitoring, closure, and post-closure procedures required of a facility
complying with Part 264 requirements. The solidification estimates do
not include final disposal costs and neither estimate includes
transportation costs. Even without these added costs, the cost for
solidification is comparable to that of the triple-lined disposal
facility, and the landfarming cost far exceeds that of the triple-lined
facility.
The Estimated Impact of Alternative Waste Management Practices
Alternative treatment and disposal methods are not being pursued by
the geothermal industry. Nevertheless, at some future time, alternative
disposal practices may be required. Therefore, in order to provide some
guidance on the potential cost impact of these alternatives, the costs
81
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Table IV-4 Annualized Per Barrel Surface Impoundment Cost
Tvoe of facility Cost
Unlined, one-quarter acre $2.04
Single-lined, one-quarter acre 4.46
Single-lined, 15-acre 1.04
Triple-lined, 15-acre 6.78
Source: Estimates contained in Volume 1 of this report.
82
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for several waste management practices are presented in Table IV-5. The
alternatives are those discussed above.
Forecast of Future Profitability for the Geothermal Industry
The recent declines in energy prices and demand for electrical
power, as well as cutbacks in government support and incentives, have
resulted in a consolidation phase for the geothermal industry.
Development will continue at The Geysers in northern California, however,
because of the area's favorable economics situation. Exploration for new
resources has dropped significantly, with most new drilling occurring at
currently operating fields (Wallace 1986).
Geothermal energy production increased during 1986, primarily
because of increases in direct use projects and small-scale modular
binary units for reduced-cost electrical power generation. Electrical
power generation capacity for 1986 remained basically unchanged from
1985. Under the current energy market conditions, future developments
will be restricted to expanding existing economic fields (Wallace, et al.
1987). As existing older plants reach their economic life and are phased
out, geothermal electrical power generation capacity may actually
decrease, resulting from the poor economics and the higher economic risk
involved in establishing a new facility rather than in operating an
existing one in the current energy market.
The future profitability of the geothermal industry is tied directly
to the price of energy available from other sources, primarily
hydrocarbon fuels. When the price of these fuels rises again, the level
of new geothermal field development will increase as well. For most
current producers, the profit margins have been reduced significantly in
the past several years.
83
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CO
Table IV-' lota) Annual Cost of Alternative Waste Management Practices
(In 1985 dollars, based on 1985 waste volumes)
Location
Waste management alternative The Geysers Imperial Valley Other
One-quarter acre, un lined surface impoundment $ 108,936 $ 112.404 $ 4,896
One-quarter acre, single lined, surface impoundment 238.164 245,746 10,704
Fifteen acre, s ing le-1ined. surface impoundment 55,536 57,304 2.496
Fifteen acre, tr iple-1 ined, surface impoundment 363,120 374,680 16.320
lhirt>-fwe acre, pre-interim status landfarm 853,866 881.049 38.376
Thirty-five acre, Part 264 compllance landfarm 1.942,692 2,004.538 87,312
b.c
Solidification 320.400 330,600 14,400
transportation cost excluded from all alternatives
Final disposal cost not included
GBased on average cost of 16 per barrel
-------
CHAPTER V
DAMAGES CAUSED BY GEOTHERMAL OPERATIONS
A total of 42 State and local contacts were made in connection with
geothermal energy damage cases. No significant cases of damages were
found associated with the exploration, development, or production of
geothermal energy. In fact, only two incidents relating to potential
damage cases were identified. The two reports of pollution from
geothermal waste in The Geysers area of California were obtained from the
California Division of Oil and Gas.
One of The Geysers incidents occurred in Lake County, where a waste
sump containing drilling fluids and bentonite muds was pumped and
discharged into an adjacent gully during a period of high rainfall. This
discharge caused a temporary increase in the turbidity of a nearby
stream, resulting in a small fish kill. The incident was published in a
local newspaper, but was not officially documented or studied. This
incident was exceptional because there are established procedures for
injecting waste drilling fluids during periods of unusual rainfall.
In Sonoma County, a sump-pumping truck loaded with drilling fluids
and brine illegally dumped its contents along a roadside. This incident
was documented by the local Regional Water Quality Control Board.
The lack of significant damage cases indicates that existing
regulatory programs are probably effective.
85
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-------
CHAPTER VI
RISK ASSOCIATED WITH GEOTHERMAL OPERATIONS
INTRODUCTION
Section 8002(m) of the Solid Waste Disposal Act, as amended in 1980,
requires EPA to conduct a detailed and comprehensive study of drilling
fluids, produced fluids, and other wastes associated with the
exploration, development, and production of geothermal energy.
Furthermore, Section 8002(m)(1)(C) specifically directs EPA to analyze
the potential danger to human health and the environment resulting from
these activities.1 A risk analysis undertaken to help fulfill the
requirements of Section 8002(m)(1)(C) is presented in this chapter.
The objectives of this assessment were to:
. Characterize the major risk-influencing factors (i.e., waste
types, waste quantities, waste management practices, and
environmental settings) associated with geothermal energy
activities;
• Attempt to identify the types of wastes, management practices,
and environmental settings that occur most frequently across the
spectrum of geothermal energy facilities/sites, within the
limitations of available data;
• Develop model facilities based upon characterization of the
geothermal energy industry; and
• Qualitatively assess the range of potential baseline health and
environmental risks posed by the model facilities developed.
References in this chapter to geothermal energy facilities, sites, or activities
generally refer to exploration, development, and production operations.
87
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For the geothermal energy industry, a qualitative analysis rather
than a quantitative risk modeling analysis was conducted. The analysis
was based on data and information gained from a literature review; these
data have been summarized in the preceding chapters of this report. The
industry data available from the literature are neither comprehensive nor
fully reliable. For example, the reliability of the waste composition
data is suspect because of the lack of reported quality assurance
controls. EPA's literature review was supplemented by site visits and by
an examination of environmental settings at geothermal energy sites.
Overall, EPA has determined that the quantity and quality of data
available do not warrant quantitative risk modeling at this time. In
addition, because of the limited data available and the lack of
comprehensive data on all but a few facilities, EPA has chosen to assess
risks by analyzing a range of conditions at "model facilities" rather
than by analyzing the conditions at individual existing facilities.
In conjunction with this report, EPA prepared a risk assessment
report on the oil and gas industry (Volume 1, Chapter V). The oil and
gas risk analysis is based primarily on a quantitative risk modeling
approach. Because the waste types and waste management practices for the
two industries are similar, EPA used the initial risk results for oil and
gas activities as a reference for qualitative assessment of the potential
risks posed by the geothermal energy model facilities. Throughout this
chapter, analogous elements of the oil and gas risk analysis are
discussed.
Scope and Limitations
This analysis addresses geothermal operations for the industry as a
whole (rather than for a single facility or a limited geographical area),
and considers a range of values for important risk-influencing variables
to assess potential health and environmental effects under a variety of
conditions.
88
-------
In accordance with Section 8002(m) and as a practical matter, however,
EPA concluded that it was necessary to limit the scope of this study. The
important limitations in scope (i.e., areas EPA has not attempted to
assess) include risks from wastes not covered by the RCRA, Section 3001
(b)(2)(A) exemption (i.e., wastes already covered by RCRA regulations);
risks from releases regulated and permitted under Federal statutes other
than RCRA (e.g., the Clean Air Act); and risks associated with various
alternative waste management practices (i.e., this study only concerns
current practices).
Probably the most important limitation to this analysis is the lack
of reliable data on the composition of geothermal energy industry wastes.
In many cases, therefore, EPA analyzed the risks at geothermal sites
based on the constituents and concentrations estimated for oil and gas
wastes. Waste streams generated by exploration activities for the
geothermal industry are very similar to those generated by exploration
for the oil and gas industry (drilling wastes). Both industries dispose
of the majority of liquid production wastes through subsurface injection.
CHARACTERIZATION OF MAJOR RISK-INFLUENCING FACTORS
The potential health and environmental risks associated with waste
management activities depend on the types and quantities of wastes being
generated; the storage, treatment, and disposal technologies being used;
and the environmental settings in which the waste management activities
are conducted. These factors determine the degree to which receptors
(human or environmental) may be exposed to harmful constituents of the
waste through various exposure pathways. The following sections
characterize the major waste streams, waste management practices, and
environmental variables that influence risks at geothermal facilities.
Waste Streams
The characterization of waste streams generated from geothermal
energy industry activities was based solely on a literature review.
89
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General data gathering methods are discussed in Chapter I. As stated
previously, this review provided no comprehensive or fully reliable data.
EPA focused characterization efforts on the two large-volume waste
types associated with the two major geothermal energy industry operations
included in this study: drilling (i.e., exploration and development) and
production. As shown in Figure VI-1, these two waste types are drilling
pit wastes (drilling mud and well cuttings) and production waste fluids.
Most data available in the literature concern these wastes. Although
other types of wastes are generated by geothermal energy activities, EPA
had inadequate data on their chemical characteristics, sources and
volumes, and management practices to assess the risks.
To perform the qualitative risk assessment for geothermal energy
industry wastes, EPA compared model geothermal energy facilities to oil
and gas models with similar waste type, waste management, and
environmental setting characteristics. Consequently, in characterizing
geothermal energy industry wastes, EPA emphasized constituents chosen for
modeling risk in the oil and gas analysis. According to the limited
geothermal waste characterization data available, the constituents
analyzed in the oil and gas study also appear to present the greatest
potential for risk from geothermal wastes.
Produced Fluid Wastes
For purposes of this risk assessment, EPA divided geothermally-
produced fluid waste streams into two main categories: power plant
fluids and direct user fluids. The power plant category was further
divided into three subcategories based on the processes used to convert
geothermal energy into electric power: the conventional steam cycle, the
binary process, and the flash process. EPA differentiated between the
90
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EXPLORATION AND
DEVELOPMENT
WASTES
PRODUCTION
WASTES
PRODUCTION
WASTE SOLIDS
PRODUCTION
WASTE FLUIDS
MISCELLANEOUS WASTES'
(E.G., DECK DRAWINGS)
DRILLING PIT WASTES
(POWER PLANT SITES ONLY)
220.000 BARRELS/YEAR"
PRODUCED FLUID PRECIPITATES-
PIPE SCALE*
DIRECT USERS
(122 OPERATIONS"')
GEOTHERMAL
FLUID WASTES
>8,000 MGAL/YEAH"
POWER PLANTS
(23 OPERATING FACILITIES)
GEOTHERMAL
FLUID WASTES
57,000 MGAL/YEAR"
CONVENTIONAL STEAM PROCESS
(5 FACILITIES)
GEOTHERMAL
FLUID WASTES
BINARY PROCESS
(10 OPERATING FACILITIES)
GEOTHERMAL
FLUID WASTES
22,000 MGAL/YEAR"
FLASH PROCESS
(8 OPERATING FACILITIES
GEOTHERMAL
FLUID WASTES
<35,000 MGAL/YEAR
Figure Vl-1 Exempt Wastes Generated from Geothermal Energy Industry Activities
Wastes not Included in the analysis.
Total quantity from all facilities and sites.
While the actual number of direct user operations is unknown, 122 were identified in the literature. Produced waste fluid quantities were determined for only 112 of these 122 operations.
-------
wastes from these processes because of differences in waste
characteristics. These subcategories are discussed below.
Production Fluid Wastes—Conventional Steam Cycle
As discussed in Chapter II, two basic types of geothermal
(hydrothermal) fluids exist: fluids from vapor-dominated hydrothermal
systems and fluids from liquid-dominated hydrothermal systems. Fluid
from vapor-dominated hydrothermal systems can be used directly to drive
the power turbine in a conventional steam cycle process. In this
process, the waste is generated downstream of the turbine when exhaust
steam is condensed in direct contact condensers or surface condensers
located beneath the turbine. It should be noted that The Geysers (the
only vapor-dominated reservoir under commercial development in the United
States) accounted for more than 89 percent of the capacity of U.S.
electric power generation from geothermal energy in 1986.
EPA has determined that production fluid wastes generated downstream
of the turbine in vapor-dominated systems are currently exempt wastes
under RCRA. However, this report does not explicitly address the risks
associated with these wastes because of inadequate data on their volumes,
constituent concentrations, and management practices. In general, steam
extracted from the ground in vapor-dominated systems is relatively pure
because most of the dissolved minerals are left behind in the formation.
Constituent concentrations in the condensed liquids, therefore, are
probably comparable to (or possibly less than) the concentrations in
produced fluid wastes from the binary and flash processes discussed
below. Also, produced fluid wastes from vapor-dominated systems are
generally injected underground in a manner similar to that practiced for
binary and flash process fluids. For these reasons, the risks associated
with production fluid wastes from vapor-dominated systems are probably
within the range of those discussed for the binary and flash processes.
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Production Fluid Wastes — Binary Process
In the binary process, hot geothermal fluids heat and vaporize a
hydrocarbon heating medium. The hydrocarbon vapor then drives the power
turbine. The fluid wastes produced are exempt wastes and are generated
upstream of the turbine.
In Table III-4, produced fluid analyses were presented for five
binary process power plants. Two model waste streams, shown in
Table VI-1, were developed from these analyses. Several constituents in
Table III-4 have been combined into a mobile salt constituent in these
model waste streams. The first model waste stream contains the median
concentration of each constituent in the five analyses and may be
considered a "best estimate." The second stream may be considered a
conservative waste stream because it is composed of the highest
concentration of each constituent in the produced fluid analyses. The
constituent concentrations for the oil and gas model waste streams, which
were used as references in performing the qualitative risk assessment,
are shown for comparison in Table VI-1.
As shown in Table VI-1, data are available for only four of the six
constituents modeled in the oil and gas risk analysis. The geothermal
fluid analyses include neither benzene nor arsenic. Benzene in oil and
gas waste streams probably results from hydrocarbon contamination,
oil-based drilling fluids, or diesel fuel additives in mud systems; its
presence would not be expected in fluids from normally pressured
geothermal reservoirs. Although evidence exists that arsenic is likely
to be present in these waste streams as a trace constituent,
concentrations are not provided in these "major-constituent-only"
analyses. Trace analyses performed on samples from several test wells
(i.e., exploration wells) and provided in Tables III-6 and III-7 show the
presence of arsenic in concentrations ranging from 0.25 to 25 mg/L
(Acurex 1980; Morris, et al. 1981).
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Table VI-1 Model Production Fluid Waste Stream Analyse:.
Model oil and gas waste
strean' concentrations (mq/L
Model geothennal power plant
waste stream concentrations (mq/L)
Geothermal direct user
operation waste stream
concentrations (mq/L)c
Waste stream Median Upper 90th X
cons 1 ituerit
Arsenic 00 17
Benzene OS 29
boron 9 S 120 0
Chloride 7.JOO 35,000
Sodium 9,400 67.000
Mobile Salts6 23,000 110,000
Binary process Binary process Flash Range Median
best estimate3 conservative3 process
NAd NA NA NA HA
NA NA NA NA NA
50 49 210 0.0 - 277 0.6
865 9,000 93,650 0.0 - 11.000 58
653 4,720 36,340 4.0 - 7.000 195
1.694 14,842 153,198 8.6-20,568 474
based on produced fluid analyses of samples from five binary process power1 plants
li
or; the produced fluid sample analysis from a flash process power plant
Based on produced fluid san.ple analyses from 43 direct user operations in 13 States identified in the literature.
NA = Not available In the case of arsenic, however, trace analyses of samples from several test wells suggest that arsenic is
present in produced geotherma) fluids
eMobile Salts - Na + C1 + K + Mg + Ca -t SO
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As described in Chapter III, produced fluid waste volumes were
calculated for all ten operating binary process power plants. The total
volume generated from these plants is approximately 22,000 Mgal/yr
(million gallons per year). For individual facilities, produced fluid
waste generation rates range from 240 to 7,700 Mgal/yr, with a median
rate of 1,200 Mgal/yr.
Production Fluid Wastes — Flash Process
In the flash process, steam is produced by subjecting fluids produced
from a liquid-dominated reservoir to a sudden pressure reduction. The
steam generated directly drives a power turbine. The loss of some water
to steam concentrates the dissolved solids in the remaining geothermal
fluid. This remaining fluid is an exempt waste.
Only one waste stream analysis of fluid waste is available. This
waste is generated upstream of the power turbine; its analysis is
presented in Table VI-1. In the absence of additional data, EPA used
these data to analyze risk associated with fluids produced from flash
process power plants. Although arsenic levels are not reported in this
"major-constituent-only" analysis, test well analyses indicate that
arsenic is likely to be present in these wastes. The levels of arsenic
may be higher in the waste stream than are shown in the test well
analyses, because flashing concentrates the dissolved solids in the fluid.
For all eight operating facilities in the United States that generate
power by the flash process, EPA estimated that approximately 35,000 Mgal
of produced fluid wastes are generated annually. The waste generation
rate at individual flash process facilities ranges from 59 to
12,000 Mgal/yr, with a median rate of 3,000 Mgal/yr.
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Direct User Fluid Wastes
As described in Chapter II, geothermal fluids are also used as a
direct source of heat. Based on chemical analysis data, the produced
fluid wastes from direct user applications generally contain lower levels
of chemical constituents than do fluids from power plants. Table VI-1
shows the range of concentrations and the median concentration of each
major constituent found in analyses of produced fluids from 43 direct
user operations in 13 States.
EPA identified a total of 122 direct user operations in the
literature; the actual number of sites is unknown. Produced fluid
generation rates were given for only 112 of the operations cited. These
112 facilities generate approximately 8,000 Mgal/yr of produced fluid
wastes. The quantity of fluid waste generated at a given site ranges
from 3,.7 to 4,200 Mgal/yr; the median quantity is approximately
110 Mgal/yr.
Drilling Pit Solid Hastes
As discussed in Chapters II and III, drilling pit wastes consist
primarily of used drilling muds and well cuttings. The drilling pit
solid waste analyses from eight sites are presented in Table VI-2, with
the corresponding constituent concentrations for the model oil and gas
waste streams provided for comparison. From the data available, two
model waste streams were characterized. The first waste stream is a
"best estimate" composed of the median concentration of each constituent
in the eight analyses; the second is a "conservative" model waste stream
characterized by the maximum concentration of each constituent. Although
arsenic concentrations are not given in the geothermal analyses in
Table VI-2, extract analyses presented in Tables III-ll and 111-12 for
the same sites (see Chapter III) show the presence of arsenic in some
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geothermal drilling pit wastes. EPA elected not to use extract analyses
because they do not present explicit concentrations for many trace
elements. Instead, concentrations are reported as being less than the
detection limit of the analytical technique used.
In 1985, the geothermal energy industry generated 220,000 barrels of
drilling pit wastes from the 68 wells drilled (Williams 1986). The mean
quantity of waste generated per drilling pit is 3,200 barrels, based on
one pit for each well. This mean quantity was used to characterize the
model geothermal drilling pit waste stream.
Waste Management Practices
Waste management practices for the geothermal energy industry were
characterized based on data compiled from a review of the literature and,
in a few cases, data collected during site visits. With the limited data
available, EPA attempted to define the factors that can affect risk,
including:
*
• Principal treatment and disposal technologies;
• Basic design and operating information; and
• Unit size and waste throughput.
When data were not available on the basic design, operating
parameters, and/or unit size/waste throughput, EPA characterized waste
management practices with the values used for similar practices in the
oil and gas risk analysis. In the following sections, waste management
practices are described for each waste type analyzed.
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Table VI-2 Drilling Pit Solid Wastes bulk Composition
vO
CD
Model oil and gas waste
wtream concentrations
a
Pit solids - Direct (mq/kq) Geothermal energy drilling sites (mq/kg)
Waste stream Median Upper 90th XABCDE FGH
const ituent
Arsenic 0 0 01 NAb NA NA NA NA NA NA NA
Cadmium 2 54 NA NA NA NA NA NA NA NA
Sodium 6,500 59.000 7,700 4.000 20,000 12,500 2.400 900 1,100 1.900
Chloride 17.000 88.000 9,800 1,000 53,000 20.000 1,000 100 100 400
Fluoride c c 240 340 290 420 230 180 240 150
Chromium VI 22 190 NA NA NA NA NA NA NA NA
Mobi le
Saltsd 100,000 250,000 32.600 36,700 111.600 77,000 27.800 33.200 26,300 31.600
Best
estimate Conservative
NA NA
NA NA
3,200 20.000
1,000 53,000
235 420
NA NA
32.900 111.600
Trie constituent concentrations in waste streams A through H are based on analyses of drilling pit wastes at eight geothermal energy industry drilling
sites. These drilling sites are associated with geothermal energy power plants The best-est imate waste stream comprises the median concentration of each
constituent in waste streams A through H The conservative waste stream comprises the highest concentration of each constituent in waste streams
A through H
^Kn = Not aval lablfc
Fluoride was not a model constituent in the oil and gas study
d
Mobi)e Salts = Na + Cl + K + Mg + Ca + S04
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Production Fluid Wastes — Power Plants
As shown in Figure VI-2, produced fluids from geothermal energy power
plants may be disposed of by a variety of methods. The methods currently
practiced include:
• Direct release to surface waters;
• Injection (or treatment and injection) into underground strata;
and
• Consumptive secondary use.
Several other methods described in the literature and discussed in
Chapter III are not being employed at present.
Of the current waste management practices, injection is the most
frequently used. In fact, injection is the primary geothermal fluid
disposal method for 21 of the 23 operating power plants that generate
exempt wastes (under Section 3001).
Because the overwhelming majority of power generation facilities
dispose of produced fluid wastes by underground injection, EPA analyzed
the risks associated with this waste management practice at power
plants. The two key variables that influence the risk posed by injection
of wastes are injection rate per well and injection pressure. Based on
the limited data on injection rates and numbers of wells available for a
few sites, EPA estimated the injection rate per well for a flash process
facility and for a binary power plant. These estimates assume that all
injection wells normally operate continuously. If some injection wells
are non-operating spares, the estimated rates will be less than the
actual rates. The estimated injection rates per well for binary process
plants and flash process plants are 950 Mgal/yr and 610 Mgal/yr,
respectively.
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PRODUCTION
WASTE
FLUIDS
1 1
\<
DIRECT USERS—
(122 FACILITIES)
, , 1 I
INJECTION
(14 FACILITIES)
O
0
DIRECT DISCHARGE IRRIGATION BINARY PROCESS
(90 FACILITIES) (2 FACILITIES) (10 FACILITIES)
\ 1
V 1 ' 1 '
INJECTION OR DIRECT DISCHARGE FISH FARM + DIRECT
TREATMENT/INJECTION TO SURFACE WATER DISCHARGE
(8 FACILITIES) (1 FACILITY) (1 FACILITY)
\
i
POWER-
GENERATION
PLANTS"
(23 FACILITIES)
\
i \ I
CONVENTIONAL STEAM
PROCESS
(5 FACILITIES)
1
!
INJECTION
(5 FACILITIES)
FLASH PROCESS
(8 FACILITIES)
\ i
V "
INJECTION OR COOLING TOWER
TREATMENT/INJECTION MAKEUP WATER
(8 FACILITIES) (2 FACILITIES)
Figure VI-2 Waste Management Practices* for Produced Geothermal Fluid Wastes
More than one type of wasta management practice may be used at • facility.
1 Only practices at facilities generating exempt waste are shown.
The literature identified 122 direct user operations; the actual number Is unknown. Waste management practices were determined for only 106 of these operations.
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The other key variable that influences risk is injection pressure.
The injection pressure was varied from 400 to 2,000 psi for the modeled
oil and gas scenarios that best represent the conditions at geothermal
sites. EPA evaluated the potential risk posed by the reinjection of
geothermal wastes for this range of injection pressures for all power
plant model facilities, because no data were available in the literature
on their field injection pressures.
Production Fluid Wastes — Direct Users
Based on a sample of 106 direct user operations in 12 States, the
primary disposal method for produced fluid wastes from these operations
is direct discharge to surface water. More than 85 percent of the direct
users in this sample (90 operations) dispose of their fluid wastes in
this manner. The vast majority, if not all, of these operations are
covered under NPDES permits.
After direct discharge to surface water, the most frequently employed
geothermal fluid waste management practice for direct users is
injection. Approximately 13 percent of the direct users in the sample
(14 operations) dispose of their wastes by injection. In addition, the
produced fluid "wastes" from two other operations are used for irrigation.
The 14 operations that inject produced fluid wastes make up the
largest segment of the direct user operations covered under the scope of
this study. Therefore, EPA chose injection to evaluate the potential
risks from direct user operations. For direct users injecting geothermal
fluid wastes, the annual waste generation rate per facility ranges from
9 to 500 Mgal/year; the median rate is 55 Mgal/year. These fluid rates
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could be handled by one injection well at each site. Assuming one
injection well at each site, the median rate (i.e., 55 Mgal/year) was
used to evaluate the potential risk from direct user injection. The
injection pressure was assumed to vary between 400 and 2,000 psi for the
same reasons noted for power plants.
Drill ing Pit Wastes
In reviewing the literature, EPA identified four methods for handling
drilling pit wastes:
• Dewatering and onsite burial;
• Removal for offsite disposal;
• Landfarming; and
• Solidification of pit wastes.
As stated in Chapter IV, however, EPA found only two references in
the literature addressing the handling and disposal of geothermal
drilling wastes at field sites. At one site, drilling pit wastes were
discharged to a reserve pit and then removed for offsite disposal
(USDOE 1980). At another site, drilling pit wastes were tested, then
removed for offsite disposal if they were determined to be hazardous. On
the other hand, if the test showed the wastes to be nonhazardous, the pit
was dewatered by allowing the liquids to evaporate, and then backfilled
(i.e., onsite burial) (Royce 1985). Both sites were located in
California and the practices used reflect California regulatory
policies. There is also evidence that some operators collect drilling
wastes in tanks rather than in drilling pits (Morton 1987).
Data on the waste management practices for geothermal drilling wastes
were not available to determine the one most frequently employed.
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Consequently, EPA elected to characterize model geothermal sites by the
same disposal methods as are used to characterize the oil and gas sites.
These methods are onsite burial of dewatered drilling pit wastes in
unlined and synthetically lined pits. Based on the limited waste
management practice information available, geothermal drilling pit wastes
appear to be handled, for the most part, more stringently than those in
the oil and gas scenarios modeled. Therefore, characterizing model
geothermal industry drilling sites by onsite burial may be a conservative
assumption (i.e., one that could lead to overestimates of risks).
The two risk-influencing variables modeled for onsite reserve pits in
the oil and gas analysis were pit size and the presence or absence of
synthetic liners. The average volume of geothermal drilling waste per
pit is 3,200 barrels, which falls between the medium-sized
(5,900 barrels) and small-sized (1,650 barrels) oil and gas drilling pits
modeled. Risks were evaluated for both the unlined and synthetic-lined
pits modeled.
Environmental Settings
To obtain data on the environmental settings at geothermal energy
facilities, EPA analyzed the environmental conditions at 20 geothermal
field sites. The sites selected comprise most commercial power plants,
plus a few large direct users.
Based on previous risk analyses, EPA identified the following
environmental variables as having significant potential for influencing
risks resulting from waste releases to ground and surface water:
• Hydrogeologic variables: ground-water velocity, aquifer
configuration, recharge rate, depth to ground water, and
unsaturated zone permeability;
• Surface water variables: distance to surface water and surface
water flow rate; and
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• Exposure point characteristics: downgradient distance to the
nearest exposure well and downstream distance to the nearest
surface water intake.
The distributions of values for each variable within the 20 sites
analyzed were used to develop two environmental settings for this risk
analysis: a best-estimate setting, representing the most common setting
found at the 20 sites, and a conservative (but not necessarily
worst-case) setting. These environmental settings are presented in
Table VI-3. Single ground-water velocities were not designated for the
conservative setting because, based on previous analyses, a slow velocity
yields higher risk estimates for some waste constituents, while a fast
velocity yields higher risk estimates for other constituents. No attempt
was made to differentiate between the environmental settings for drilling
and production activities, because drilling and production are either
currently taking place, or can occur, at many of the same sites.
QUALITATIVE RISK ASSESSMENT RESULTS
This section provides a qualitative assessment of the risks
associated with the underground injection of produced fluids and the
disposal of drilling wastes in onsite reserve pits. As discussed in the
preceding section, these are the most common waste streams and waste
management practices of interest to this study; however, they are not the
only ones that could pose human health or environmental risks. Risks
associated with other geothermal waste streams and waste management
practices may be analyzed in future studies.
This assessment is mostly based on the oil and gas risk modeling
conducted in conjunction with the overall Section 8002(m) study, and is
therefore subject to the same limitations. Furthermore, little reliable
data are available on the occurrence and quantity of toxic constituents
in geothermal wastes.
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Table Vi-3 Environmental Settings at Geothermal Energy Facilities
Environmental variable
Values for variables
Best estimate
Conservative
Ground-Water Velocity 100 m/yr
Aquifer Configuration Unconfined
Recharge Rate 1 in/yr
Depth to Ground water 20 m
Unsaturated Zone Permeability 10 cm/sec
Distance to Nearest Downgradient
Drinking Water Well > 2.000 m
Distance to Surface Water -> 2,000 m
Average Surface Water Flow Rate 0
Distance to Nearest Downstream 10 km
Surface Water Intake
1 m/yr
100 m/yr
1.000 m/yra
Unconf ined
20 m/yr
j m
10 cm/sec
200 m
60 m
40 cfs
1 kn,b
d A range of velocities was examined to analyze the range of risks caused by
different chemical constituents in the conservative setting For some
constituents, a slow velocity is conservative (i.e , yields higher risk
results), while for other constituents, a fast velocity is conservative
Because of lack of data, these assumed values were chosen to reflect a
reasonable range of distances.
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Underground Injection--Produced Fluids
There are at least four release pathways whereby underground
injection of produced fluids can lead to contamination of near-surface
aquifers: (1) release through failure of the well casing; (2) release
through failure of grout seals separating injection zones from
near-surface aquifers; (3) upward contaminant migration through abandoned
wells; and (4) upward contaminant migration through fractures or faults.
Because of technical constraints and data limitations, only the first two
pathways were modeled in the oil and gas study (Volume 1, Chapter V);
thus, they are the only two considered here. The Agency recognizes,
however, that the remaining pathways may also be important sources of
contamination.
Power Plants
At most of the existing geothermal power plants (roughly 70 percent),
an injection well failure that releases produced fluids into near-surface
aquifers would not be expected to pose significant human health risks.
This assumption can be made because existing power plants are estimated
to have few drinking water wells within 2,000 meters in a downgradient
direction, making it unlikely that an individual would ingest ground
water contaminated by such a release.
The potential for exposure is much greater, however, at the few
facilities estimated to have private drinking water wells within
2,000 meters downgradient. For the oil and gas scenarios best
representing the conditions assumed to exist at these facilities, it was
estimated that injection well failures, if they occur, could result in
cancer risks (caused by exposure to arsenic) ranging from zero to
approximately 4 x 10. These risk estimates would apply to geothermal
power plants, if the geothermal produced fluids have the same arsenic
106
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concentrations as are estimated for oil and gas industry produced fluids
(0.02 to 2 mg/L). As discussed in the section characterizing geothermal
waste streams, available data indicate that arsenic is present in at
least some geothermal produced fluids, although the exact concentrations
are not known. In addition, it is possible that the cancer risks from
-4
injection well failures at power plants could exceed 10 , because
geothermal power plants generally inject produced fluids underground at
much higher rates and in greater volumes than the oil and gas scenarios
modeled. They thus have the potential to release larger masses of
contaminants.
Injection well failures at a few power plants could also result in
sodium concentrations in downgradient drinking water wells that are high
enough to cause hypertension in sensitive individuals. Sodium
concentrations were not estimated to be at levels of concern for any of
the oil and gas scenarios that best represent releases of produced fluids
from the binary process; however, the higher injection rates and volumes
at geothermal power plants could result in higher concentrations of
sodium at exposure points. Produced fluids from the flash process have
significantly higher sodium concentrations than do fluids from the binary
process, and therefore pose a greater risk for hypertension. Results for
several relevant oil and gas scenarios indicate that releases of produced
fluids from the flash process could result in sodium exposures that could
cause hypertension in persons using drinking water wells located
200 meters or more downgradient.
The relatively high concentrations of chloride, boron, and mobile
salts (including sodium, chloride, potassium, magnesium, and other ions)
in geothermal produced fluids from power plants, and the relatively high
rate at which these fluids are injected, create the potential for
injection well failures (if they occur) to damage ground-water
resources. For example, it appears that the concentrations of chloride
107
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in produced fluids could cause corrosion in pipes, and that the
concentrations of boron and mobile salts could injure sensitive crops.
It is presently uncertain, however, how far these contaminants could
migrate in ground water before dilution would cause the concentration to
drop below levels of concern. Results from the oil and gas modeling
study suggest that releases of produced fluids from the binary process
could, in some cases, result in harmful concentrations up to 60 meters
away, while releases of produced fluids from the flash process could
result in harmful concentrations at an even greater distance.
Direct Users
Many direct users use downhole heat exchangers to extract heat from
geothermal fluids without pumping them to the surface. In these cases,
the need for fluid disposal is eliminated and the potential for adverse
health or environmental impacts is very small.
At direct user facilities that use surface heat exchange systems,
geothermal fluids are brought to the surface and subsequently disposed
of, principally by injection underground. In general, the potential for
these fluids to cause adverse health and environmental effects is
considered small because contact with people or biota is unlikely.
Although the magnitude of the impacts is expected to be smaller, an
injection well failure at direct user operations could cause health and
environmental impacts similar in nature to releases from power plants.
The principal health threats probably would be the potential for cancer
and hypertension caused by ingestion of ground water contaminated with
arsenic and sodium, respectively. Concentrations of chloride, boron, and
mobile salts could also render ground water in the vicinity of releases
unsuitable for certain uses. Available data on the composition of
produced fluid disposed of by direct users are presently insufficient to
estimate the potential for adverse effects. In general, the risks
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associated with produced fluid releases by direct users would be expected
to be less than those at power plants because the volumetric flow is much
lower in direct use operations and the water used is often of high
quality (the water source is generally the same aquifer used as a
drinking water source).
Onsite Reserve Pits—Drilling Wastes
As noted previously, it appears that most (roughly 70 percent)
geothermal power plants do not have private drinking water wells within
2,000 meters. Therefore, seepage of reserve pit contaminants into
surface aquifers at most plant sites would not be expected to pose
significant health risks, because it is unlikely that anybody would
ingest the contaminated water.
Even at those plants where drinking water wells are expected to be
within range to be affected, seepage of reserve pit contaminants is
expected to cause only minimal, if any, cancer risks. If leachates from
geothermal reserve pits contain the conservative arsenic concentration
estimated for leachates from oil and gas reserve pits (0.002 mg/L),
results from the oil and gas modeling study indicate that cancer risk
caused by the leachate should be zero in most cases, and probably never
more than 10" . Reserve pit seepage appears to present a greater
potential for noncarcinogenic risk. For a few of the oil and gas
scenarios that reasonably represent conditions that also exist at
geothermal power plants, sodium concentrations in downgradient drinking
water wells were predicted to exceed a threshold that could cause
hypertension in sensitive individuals.
The oil and gas modeling results indicate that reserve pits at
geothermal power plants should not cause significant ground-water
resource damage. Concentrations of drilling waste contaminants in ground
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water were predicted to be below levels of concern 60 meters away from
most oil and gas reserve pits. Because concentrations of the main
constituents of concern (chloride, boron, and mobile salts) appear, based
on limited data, to be lower in geothermal reserve pits than in oil and
gas reserve pits, ground-water contamination resulting from geothermal
reserve pits would probably be even less.
CONCLUSIONS
Only limited data are currently available on the major
risk-influencing factors associated with geothermal energy wastes. In
particular, EPA has little to no reliable data on the composition of
geothermal energy waste streams. As a result, strong conclusions about
the risk associated with these wastes cannot be drawn at this time.
Large-volume geothermal waste streams of interest to this study (drilling
waste and produced water) are basically similar in nature to those in the
oil and gas industry. Also, these wastes generated by the two industries
are managed and disposed of in generally similar ways. The following
conclusions are provided, therefore, based on comparisons with the oil
and gas risk analysis, and accounting, to the extent possible, for
differences in waste stream composition and volumes, waste management
practices, and environmental settings expected at geothermal sites.
• Of the 20 or so U.S. geothermal power plants, it was estimated
that 13 currently have no drinking water wells within 2,000 meters
downgradient. As a result, even if produced fluid or drilling
waste contaminants were released to near-surface aquifers at the
majority of power plants, the potential for adverse health effects
is small, because it is unlikely that an individual would ingest
ground water contaminated by such a release.
• If geothermal produced fluids have a similar arsenic
concentration to that estimated for oil and gas produced fluids,
releases from failed injection wells at geothermal power plants
could cause cancer risk levels greater than 10"^ in a few cases
(it is emphasized, however, that arsenic concentrations in
geothermal produced fluids are unknown). Risk levels of concern
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would be expected primarily at sites having nearby drinking water
wells (e.g., within approximately 200 meters) and relatively high
ground-water velocities (e.g., 100 to 1,000 meters/year).
If an injection well failure released geothermal produced fluids
into a near-surface aquifer, the resulting sodium concentrations
in downgradient drinking water wells could exceed levels that may
cause hypertension in sensitive individuals. This noncancer risk
is greatest for releases of produced fluids from flash process
power plants, which appear to have much higher sodium
concentrations than geothermal produced fluids from plants using
the binary process. Greater noncancer risks would be expected at
sites having nearby drinking water wells (e.g., within
approximately 200 meters) and relatively slow ground-water
velocities (e.g., 1 to 10 meters/year).
Adverse health and environmental impacts from injection well
failures (if they occur) at direct user sites could be similar in
nature to those expected from injection well failures at power
plants; however, the magnitude of these impacts at direct user
sites would likely be much smaller because water quality is
generally better in direct use operations and because injection
well failures at direct user sites would be expected to release
smaller quantities of contaminants than would releases from power
plants. Although releases from direct users would probably occur
closer to drinking water wells, drinking water wells in the
vicinity of direct use operations often tap the same aquifer;
therefore, waters having similar qualities are used for domestic
use and direct use applications.
If injection well failure occurred at geothermal power plants or
direct user sites, released produced fluids could sufficiently
contaminate surrounding ground water to render it unsuitable for
certain uses. In particular, resulting chloride concentrations
could result in objectionable taste (making it unsuitable for
drinking), and resulting concentrations of mobile salts could be
harmful to sensitive crops (making it unsuitable for irrigation).
In most cases, concentrations of concern are not expected to be
exceeded 60 meters downgradient, although there could be instances
in which potentially harmful concentrations exist farther away.
Based on the limited information available on the composition of
wastes from geothermal well drilling, seepage of drilling waste
contaminants from geothermal reserve pits would be expected to
cause only minor (if any) cancer risk, noncancer risk, and
ground-water resource damage.
Ill
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REFERENCES
Acurex. 1980. Identification of solid wastes in geothermal operations.
Final draft report to the EPA Technical Project Monitor. Cincinnati, Ohio.
Morris, W.F., and Stephens, F.B. 1981. Characterization of qeothermal solid
waste. U.S. Department of Energy.
Morton, R.E. 1987. Salton Sea and The Geysers geothermal area trip report to
Bob Hall. U.S. Environmental Protection Agency, Office of Solid Waste.
Royce, B.A. 1985. Impact of environmental regulations on the safe disposal of
qeothermal wastes. Upton, New York: Department of Applied Science,
Brookhaven National Laboratory.
USDOE. 1980. U.S. Department of Energy. Environmental assessment.
qeothermal energy, Heber Geothermal Binary-Cycle Demonstration Project.
Imperial County, California.
USEPA. 1987. U.S. Environmental Protection Agency, Office of Solid
Waste. Onshore oil and gas and qeothermal energy exploration,
development, and production: Human health and environmental risk
assessment. Washington, D.C.: U.S. Environmental Protection Agency.
Williams, T. 1986. Department of Energy comments on the technical report
Waste from exploration, development and production of crude oil, natural
gas and qeothermal energy: An interim report on methodology for data
collection and analysis.
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CHAPTER VII
CURRENT REGULATORY PROGRAMS
FEDERAL REGULATIONS
Regulatory Agencies
The Geothermal Steam Act of 1970, as amended (U.S.C. 1001-1025),
authorizes the U.S. Department of the Interior to issue leases for the
development and use of geothermal resources. The implementing
regulations (43 CFR, Part 3200) are now administered almost exclusively
by the Bureau of Land Management (BLM). The BLM may issue leases on
Federal lands under its jurisdiction and on lands administered by the
U.S. Forest Service, with the consent of the latter. In addition, the
BLM evaluates and classifies geothermal resources on Federal land and
supervises all pre- and post-leasing operations, including exploration,
development, and production.
Geothermal Resources Operational Orders
Geothermal Resources Operational (GRO) Orders are formal,
enforceable orders, originally issued by the U.S. Geological Survey, to
supplement the general regulations found in 43 CFR, Part 3200. They
detail the procedures that lessees must follow in a given area or region.
GRO Order No. 1 outlines the BLM requirements for conducting
exploratory operations on Federal lands. Before any exploration can
begin, a Notice of Intent (NOI) to Conduct Geothermal Resources
Exploratory Operations must be submitted by the lessee to the Authorized
Officer.
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Three categories of actions are considered exploratory operations:
casual use (geological reconnaissance, sampling, or surveying)
geophysical exploration, and drilling of shallow holes for measuring
temperature gradients.
Upon cessation of exploratory operations, the lessee must file a
Notice of Completion. The Notice of Completion must include any
information on drilling difficulties or unusual circumstances that would
be useful in ensuring future safe operations or protection of the
environment. Three other protective measures set forth in GRO Order
No. 1 regarding exploratory operations are: (1) drilling fluids and
cuttings cannot be discharged onto the surface where they could
contaminate lakes and streams; (2) excavated pits and sumps used in
drilling must be backfilled as soon as drilling is completed and the
original topography must be restored; and (3) unattended sumps must be
fenced.
Geothermal Resources Order No. 2 sets forth standards for drilling,
completion, and spacing of wells. All exploratory and initial
development wells must be drilled according to the provisions of this
Order. Lessees must submit an Application for Permit to Drill; under the
terms of the Permit to Drill, the lessee must comply with requirements
for casing, blowout prevention, drilling fluids, well logging, wellhead
equipment, well spacing, and contingency plans.
Plugging and abandonment procedures are regulated under GRO Order
No. 3. The lessee must promptly plug and abandon any well that is not in
use or potentially useful. The well must be plugged and abandoned in a
manner specifically approved by the Authorized Officer.
GRO Order No. 4 requires the lessee to comply with all applicable
Federal and State standards with respect to the control of air, land,
water, and noise pollution, including the control of erosion and the
114
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disposal of liquid, solid, and gaseous wastes. According to Order No. 4,
"Liquid well effluent or the liquid residue thereof containing substances,
including heat... shall be injected into the geothermal resources zone or
such other formation as is approved by BLM." The lessee must submit a
Plan of Injection to the BLM for approval. The plan must include the
quantity, quality, and source of the proposed injection fluid, how the
fluid is to be injected, and the proposed well location and injection
zone. The plan also must take into account effects on surface and
subsurface waters, fish, wildlife, and natural habitat. Monthly Water
Injection Reports must be filed with the BLM. Solid wastes, such as
drill cuttings, precipitates, and sand, must be disposed of as directed
by the BLM, either on location or at approved disposal sites.
According to GRO Order No. 4, the lessee must provide and use pits
and sumps to retain all wastes generated during drilling, production, and
any other operation, unless other specifications are made by the
Authorized Officer.
Underground Injection Control Program
The Safe Drinking Water Act of 1974, as amended, requires EPA to
establish a national program to ensure that underground injection of
wastes will not endanger underground sources of drinking water. EPA
implemented this mandate by enacting the Underground Injection Control
(UIC) Program for Federal, Indian, State, and private lands.
EPA has primary enforcement authority and responsibility for the UIC
Program for all States, except for those having their own approved UIC
programs. In some cases, EPA gives primacy to the States regarding the
UIC program. Under the UIC rules, EPA has jurisdiction over the five
categories of injection wells. Geothermal injection wells are considered
Class V under the UIC classification system; this class includes electric
power industry injection wells, direct heat user injection wells, heat
115
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pump and air conditioning return flow wells, and ground-water aquaculture
return flow wells.
The Bureau of Land Management defers to EPA or the primacy State
when it is necessary to determine whether underground freshwater sources
are safe from the effects of these operations. However, it retains
involvement in approval of wells drilled or converted for injection on
Federal and Indian lands, principally in order to carry out other
mandated responsibilities. The BLM permits wells for production rather
than injection; in this case, the BLM is responsible for protecting
subsurface water sources near the well.
SUMMARY OF STATE REQUIREMENTS
Regulatory Requirements
State rules and regulations obtained from 35 States have been
examined for their applicability to geothermal energy exploration and
development. Thirteen State legislatures have passed laws mandating the
implementation of geothermal rules and regulations. Typically, these
regulations are very comprehensive and, in general, address permitting,
solid and liquid waste disposal, well design, well plugging, and
restoration of surface.
Of the States surveyed that do not have specific geothermal
regulations, at least nine have rules and regulations that pertain to
some aspect of geothermal exploration and development. Most of these
regulations are located in water quality control standards or oil and gas
regulations that address some areas of geothermal development, especially
drilling and injection well requirements.
The requirements of the 13 States that have specific geothermal
regulations are summarized in Table VII-1. The geothermal regulations
116
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of California, which follow, are presented in greater detail because they
are considered "model regulations" for geothermal operations and because
of the extensive use of geothermal resources in California.
Summary of California's Geothermal Regulations
State Regulatory Agencies
The following agencies regulate the geothermal industry in
California:
• The Geothermal Section of the California Department of
Conservation, Division of Oil and Gas;
• The California Energy Commission;
• The California Public Utilities Commission;
• The California Water Resources Control Board, and the nine
Regional Water Quality Control Boards;
• The California Department of Health Services; and
• County government agencies.
Geothermal Regulations
The following California statutes are either applicable or specific
to geothermal energy operations:
1. The California Environmental Quality Act (CEQA). The requirements
of CEQA must be fulfilled before drilling and use permits can be
issued. Under CEQA, government agencies must consider environmental
impacts that may result from the implementation of certain
geothermal projects. Since many projects require permits from
different agencies, overlapping agency studies could result; to
minimize duplication of agency effort and unnecessary time delays, a
CEQA procedure has been established. This procedure calls for a
lead agency to prepare the environmental documentation, and the
remaining permitting agencies to function as responsible agencies.
117
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TABLE V1I-1 SUMMARY OF STATE GEOTHERMAL
REGULATIONS
Alaska
Ca 1 ifornia
Hawaii
GEOTHEkKAL STATUTES
Geotherma) Regulations and Statutes of 1983
Alaska Statute 38 05 131 and Ch 87. Alaska
Admir, Code
See detailed sumnary following this
table
Board of Land and Natural Resources,
Ch 2. Title 13 and Ch. 183. Title 13
STATE RtGUIATORY AGENC1ES Dept of Natural Resources
Oept of Fish and Game
Alaska Oil and Gas Conservation
Board cf Land and Natural Resources
Oept of Health
CD
PERMITS ARE REQUIRID FQR Exploration
DM Ding
Redrilling or Deepenirig
Inject loo
1 I QUID WASTE DISPOSAL
REQUIREMENTS
Approval must lie given for injection
only for C !ass V nells that are allowed
underground fluid disposal Direct
imp lemuitdt ion - UIC Program
Exploration
Or111 ing
Mod ificat ion
Abandonment
Change of use
Injection (UIC)
Surface Discharge (NPDES)
High-quality, low-temperature geo-
thermal waters may be discharged to
surface waters.
SOI !D W^IF DISPOSAL
Disposal or solidification m-place of all pump-
able Mind: Drilling muds may be left in re-
serve pit (if nonhazardous) or removed to
permitted waste disposal facility
Solid wastes must be removed to off-
site permitted waste disposal
faci1ity.
WELL PLUGGING AND
ABANDONMENT.
As specified in the regulations
All equipment must be removed and
well plugged according to
regulations
SUP I-AC t RESTORATION
Not addressed in regulations reviewed
Surface must be restored to as near
its previous state as possible.
-------
Table Vll-1 (continued)
Idaho
Louisiana
6EOTHERHAI STATUTES.
(1) The Geothermal Resources Act of 1971
(Idaho Code. Chapter 40)
(2) Rules and Regulations: Drilling for
Geothermal Resources
(3) Rules and Regulations Governing the
Issuance of Geothermal Resources Leases
Louisiana Statewide Order 29-P,
Geothermal Rules and Regulations
Maryland Geothermal Resources Act,
Annotated Code of Maryland. Subtitle 8A.
STATE REGULATORY AGENCIES. Oept. of Water Resources
Dept. of Lands
PERMITS ARE REQUIRED FOR:
LIQUID WASTE DISPOSAL
REQUIREMENTS:
SOLID WASTE DISPOSAL
REQUIREMENTS:
WELL PLUGGING AND
ABANDONMENT:
SURFACE RESTORATION:
Exploration
Product ion
Injection
Modification or Deepening
Idaho has primacy for its UIC program. Sur-
face discharge allowed under specified con-
ditions.
Dept. of Natural Resources
Drilling
Conversion
Injection
Liquid waste may be stored in pits.
Reinjection and surface discharge
are permitted. Louisiana has UIC
primacy.
Specific methods for disposal of solid wastes Not addressed in the regulations re-
must be included in the lease agreement. viewed.
As specified in the regulations.
Injection and production wells must
be plugged according to regula-
tions when operations cease.
Procedures must be followed for well plugging Restore to as near a natural state as
and abandonment and surface reclamation. possible.
Dept. of Natural Resources
Dept. of the Environment
Drilling
Surface Discharge
Injection
Surface discharge requires approval of
DHMH. State discharge permit or NPDES
required for leachate from pit or sump
to surface or ground water. Maryland has
UIC primacy.
Drilling wastes must be removed from pits
and disposed of at permitted waste dis-
posal facility.
Fill well with sand, clay, silt, and/or
gravel, and seal with concrete or sodium-
base bentonite clay.
Restore to as near the original condition
as possible.
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Table VI1-1 (continued)
Nevada
New Mexico
GEOTHERMAL STATUTES
Geothermal regulations passed
August 1C, 198^, can be found in Nevada
revised statutes
Geothermal Resources Conservation
Act of 1978
Oregon revised statutes ch. 522: (Laws
and administrative rules relating to
geothermal exploration and development
in Oregon, Oregon revised statutes ch
537: Low Temperature Geothermal Resource
Management
STATE REGULATORY AGENCIES-
Oept of Minerals
Dept of Conservation and Natural Resources
Dept of Energy and Minerals, Oil
Conservation Division
Oil Conservation Commission
Dept of Water Resources
Dept of Geology and Mineral Industries
Dept of Environmental Quality
Dept of Land Conservation and Development
Division of State Lands
The County Affected
PERMITS ARE REQUIRED FOR.
The following well types.
Domestic
Coiimerc lal
Industrla 1
Observational
Plugging ar>d Abandonment
Injection
Exploration
Product ion
Observation or Thermal Gradient Well
Inject ion
Dr 1 1 1 ing
NFDES
Water Pollution Control
Reinject ion
Disposal
LIQUID WASTE DISPOSAI
REQUIREMENTS
SOt ID WASTE DISPOSAL
REQUIREMENTS
WE LI PLUGGING AND
ABANDONMENT
SURFACE RESTORATION
Unless an alternative is approved,
all fluid must be reinjected Nevada is a
direct implementation State for the UIC
program
Nonhazardous solid waste may be burned
onsite
As specified in the regulations
New Mexico has privacy for its UIC
program All highly mineralized waters
are reinjected according to regulations
Not stated in regulations, but common
practice is to bury drill cuttings in
reserve pits
As specified in the regulations.
Restcre to as near the original condition Not addressed in the regulations
as possible reviewed
Liquid wastes may be reinjected, or if
of high enough quality, discharged to
surface waters.
Local government is responsible for
solid waste management.
As specified in the regulation, and
subject to State Geologist approval
Restore to as near the original con-
dition as possible.
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Table VII-1 (continued)
Texas
Utah
GEQMRHAl STATUTES
Texas Annotated Code, Chapter 16,
regulates oil, gas. arid geothermal
act ivit les
STATE REGUIATORY AGENCIES Texas Railroad Commission
Geothermal Resource Conservation Act of Geothermal Energy Regulations
1961
Department of Natural Resources
of the Dept of Mines, Minerals,
and Energy
Dept of Mines, Minerals, and Energy
PERMITS ARE REQUIRED FOR-
UQUJD WASTE DISPOSAL
REQUIREMENTS
SOLID UASTE DISPOSAI
REQUIREMENTS
WEIL PLUGGING AND
ABANDONMENT
Drilling Exploration
Deepening P roduc 11on
Plugging Abandonment
Injection Injection
Waste Discharge (NPDES)
Drilling Fluid Storage and Disposal
Liquid wastes can be disposed of in drilling Liquid wastes are reinjected Utah has
fluid disposal pits, completion pits, and primacy for its UIC program.
saltwater disposal pits Geothermal
resource fluids, mineralized waters, and
brines may be injected into the
reservoir of origin, nonproducing zones,
or aquifers unfit for use.
Texas has primacy for its UIC program
Drill cuttings, sand, silt, and inert waste All solid waste must be taken to a
may be landfilled onsite without a permit permitted facility
Must proceed according to API standards
As specified in regulations.
Exploration
Product ion
Injection
Geothermal fluids must be reinjected into
the formation from which they were drawn.
Virginia is a direct implementation State
for its UIC program.
Drilling muds must be removed from the
drill site and disposed of as specified
in the operations plan
As specified in the regulations.
SURFACE RESTORATION
Provisions are usually part of the lease
agreement
Owner/operator is required to rehabili-
tate land
The operations plan must present the
intended plan for reclamation of land
at production and injection sites.
Drilling sites and pits must be re-
claimed within one year after drilling
ceases
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Table VII-1 (continued)
GEOTHERMAl STATUTES
S1ATE RtGUlAlORr AGENCIES
PERMITS ARE REQUIRfD FOR
LIQUID WASTE DISPOSAL
REQUIREMENTS
Washington
Geotherrnal Resources Act cf 1974
Department of Natural Resources
Department of Ecology
Dri 11 ing
Redrilling and Deepening
Inject ion
Wastes Discharge
Geothermal fluids are either reinjected or
discharged to surface waters Washington
has primacy for the UIC program
SOLID WASTE DISPOSAL
REQUIREMENTS
WEU PLUGGING AND
ABANDONMENT
SURFACE RESTORATION-
Wastes must be tested for hazardous
characteristics Wastes that are non-
hazardous may be backfilled in a pit or
landspread and incorporated into surface
soi Is
As specified in the regulations
Equipment and structures must be removed
Surface must be restored to as near its natural
condition as possible Surface grading and
revegetation are required
-------
2. California Administrative Code, Title 14, Chapter 2: Implementation
of CEQA. This chapter of the Code defines the scope of the CEQA
regulations, designates the lead agency, and sets guidelines for the
CEQA process with regard to geothermal exploratory projects.
3. California Administrative Code, Title 14, Chapter 4, Subchapter 4:
Division of Oil and Gas Statewide Regulations. This subchapter
provides detailed guidelines for drilling, blowout prevention,
production, injection, subsidence, and abandonment.
4. California Administrative Code, Title 23, Chapter 3, Subchapter 15.
This subchapter covers discharges of wastes to land from sumps,
ponds, landfills, and other waste management units.
5. California Administrative Code, Title 22, Chapter 30. This chapter
establishes criteria for determining if a waste is hazardous,
designated, or nonhazardous.
6. The Porter-Cologne Water Quality Control Act, California Water
Code. This law covers discharges into the waters of the State from
many waste sources.
7. California Public Resources Code, Chapter 4, Division 3 (Publication
No. PRC02, Jan. 1985): California Laws for the Conservation of
Geothermal Resources.
8. California Administrative Code, Title 20, Chapter 2, Subchapters 1,
2, and 5: California Energy Commission, Regulations Pertaining to
Rules of Practice and Procedure and Power Plant Site Certification.
9. California Assembly Bill No. 2948, The Tanner Bill. This law
requires local jurisdictions to prepare hazardous waste management
plans describing types of waste streams, waste management practices,
and treatment.
Permits
A Notice of Intention must be submitted for approval by the
appropriate district office for drilling an exploration, development,
injection, or temperature observation well, and for reworking, converting
to injection, or abandoning an existing well. Well type determines the
permitting procedure required for drilling, producing, injecting, and
abandoning geothermal wells.
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The California Department of Conservation, Division of Oil and Gas,
issues Underground Injection Control (UIC) Permits for geothermal
injection wells. California is a direct implementation State for its
underground injection program.
The California Water Resources Control Board issues NPDES permits,
and the nine Regional Water Quality Control Boards issue Waste Discharge
Permits within their respective regions for discharges of produced waters
and drilling wastes.
The local, city, or county governments issue Land Use Permits for
geothermal operations and for disposal facilities.
Well Design
Extensive design specifications are required for all types of
geothermal wells.
Solid and Liquid Waste Disposal
Disposal of nonhazardous solid and liquid wastes from geothermal
operations falls primarily under the jurisdiction of the Department of
Conservation, in the Division of Oil and Gas, and the California Regional
Water Quality Control Board; hazardous geothermal wastes are regulated by
the Department of Health Services.
Liquid Waste Subsurface Injection
The Division of Oil and Gas is in charge of all geothermal injection
projects, whether for disposal of spent nonhazardous geothermal fluids
from power production or for reservoir pressure maintenance. Geothermal
injection wells are Class V under the Federal UIC Program. The Division
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is mandated by law to ensure that no damage to the surface or subsurface
occurs as a result of injection projects. The Division decides whether
to approve or reject an application for a project based on extensive data
from the operator. Operators of proposed projects must give proof to the
Division that a reservoir will not suffer damage and freshwater aquifers
will not be infiltrated. The Division shares the submitted data and a
draft of the proposed permit conditions with the Regional Water Quality
Board. The Board then determines whether or not the draft conditions,
prepared by the Division, provide protection to the ground and surface
waters having present or anticipated beneficial uses. Upon agreement of
the conditions, the Division issues the final project permit.
Project approval cannot be given until an aquifer exemption is
granted by the Federal EPA, or until it is known that the total dissolved
solids content (TDS) of the injection zone is greater than 10,000 ppm.
Exemptions are not required to inject into a formation with water that
has a TDS content greater than 10,000 ppm, and/or is proven to be unfit
as a source of drinking water. If the EPA grants the aquifer exemption
and the appropriate agencies give the project a favorable review, the
District Engineer will approve the application for the injection
project. The Regional Water Quality Control Board is the primary
reviewing agency for proposed injection wells. Injection wells must be
inspected by the District Engineer every 6 months to ensure that the well
is in good condition and there is no leakage. A Monthly Injection Report
must be submitted by the operator to the appropriate district office,
providing injection data and information on any changes or remedial work.
Surface Disposal--Water
The Porter-Cologne Water Quality Control Act prescribes waste
discharge requirements as established by the Water Resources Control
Board. Operators must file a report with their Regional Water Quality
125
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Control Board on the proposed discharge, providing all information that
the regional board may require. The Division of Oil and Gas receives
copies of, reviews, and may reply to the draft Waste Discharge
Requirements proposed by the regional board, for all proposed discharges
within a geothermal field boundary. If protection of water quality and
precautions against pollution and contamination appear adequate, the
board will issue a Waste Discharge Permit (California's NPDES permit) to
discharge wastes to the surface waters of the State. The regional boards
must implement requirements at least as stringent as those of the State
board; some regions have established requirements more stringent th-an
those of the State board. Surface discharge for beneficial uses, such as
agricultural uses, is allowed if water quality meets the regional board's
standards. Discharge permits will specify the maximum chemical
constituent values allowed for beneficial uses.
Surface Disposal--Land
Land disposal of nonhazardous drilling wastes from geothermal
operations is under the jurisdiction of the Regional Water Quality
Control Board and the county in which the project is being implemented.
Land disposal of nonhazardous solid wastes from power production and
hazardous wastes from either drilling or power production is under the
jurisdiction of the Department of Health Services.
During drilling operations, all drilling wastes are contained in
sumps. The counties, lead agencies for geothermal resource development,
issue Use Permits for each site, which incorporate county waste disposal
requirements. Waste Discharge Requirements, issued by the Regional Water
Quality Control Board on a site-by-site basis, serve as the primary
discharge permit.
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At the end of drilling operations, State regulations require that
the materials in the sump be analyzed for listed chemical constituents,
using the California Department of Health Service's Waste Extraction
Test. Total threshold level concentrations (TTLC) and soluble threshold
level concentrations (STLC), established under California Administrative
Code 23.3.15, are the bases for determining whether a waste is hazardous.
Sump contents are generally considered hazardous if any of the
following chemical constituent levels are exceeded:
Constituent mq/L of Extract
Arsenic 5.0
Boron 100.0
Cadmium 1.0
Chromium III 25.0
Chromium VI 5.0
Mercury 0.2
Nickel 20.0
Zinc 250.0.
California Administrative Code 23.3.15, Appendix III, lists other
chemical constituents, the presence of which in the waste would result in
hazardous classification. All hazardous waste must be disposed of in a
Class I waste management unit, which has the highest containment level of
any class. Sump contents that may contain any of the listed constituents
but in lower concentration than the hazardous concentration, are called
designated wastes. Most drilling wastes are classified as designated
wastes. California Administrative Code Title 22, Division 4, Chapter 30,
establishes the waste extract concentration differences between hazardous
and designated waste categories. Designated wastes can be disposed of in
either Class II or Class I waste management units.
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Table VII-2 Summary of Waste Management Strategies
for Discharges to Land
(excluding injection to subsurface formations)
Waste
category
Liquid
Hazardous
Underwatered
Solid
Hazardous
Dry
Solid
Hazardous
Liquid
Designated
Waste
management unit
Siting and
Primary geologic
Class Type containment criteria
I Surface
Impoundment
I Landfill
I Waste
Pile
II Surface
Impoundment
Double
Liners
Double
Liners
Double
Liners
Double
Liners
(a) Natural features
capable of containing
waste and leachate as
backup to primary
containment.
(b) Not located in areas
of unacceptable risk
from geologic or en-
vironmental hazards.
(a) Natural features
capable of containing
(including
underwatered
sludge)
Underwatered
Solid
Designated
Dry
Solid
Designated
Nonhazardous
Sol id Waste
(including
dewatered
sludge and
acceptable
incinerator ash)
II
II
Landfill
Waste
Pile
III Landfill
Single
Liner
Single
Liner
None
waste and leachate
may satisfy primary
containment
requirements.
(b) May be located in
most areas except
high-risk areas.
(a) Consideration of
factors 1isted in
Subsection 2333(b)
(b) May be located in
most areas except
high-risk areas.
Source: California Administrative Code, Title 23, Subchapter 15.
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Solid wastes containing none of the listed chemical constituents are
classified as nonhazardous and may be discarded at a Class III, II, or I
waste management unit. Drilling wastes that fit the designated or the
nonhazardous classification are often dewatered and disposed of onsite.
Table VII-2 describes the various types of waste management units used in
California.
Disposal of solid wastes from power production, such as sludges and
filter cakes, is regulated by the Department of Health Services. The
Department requires plant operators to test production wastes
periodically at licensed laboratories for the listed chemical
constituents in California Administrative Code 23.3.15 (the same list as
for drilling wastes). TTLC and STLC are again the criteria for hazardous
waste designation; Class I, II, and III designations apply, and each
class of waste must be disposed of in the corresponding class of
landfill. Some production wastes in California fall into the Class I
designation; for example, solid wastes from The Geysers Power Plant are
generally treated as Class I wastes because of the presence and
concentrations of listed trace constituents.
Well Plugging and Abandonment
Requirements for injection well abandonment are determined by the
District Engineer, based on subsurface conditions and the well casing and
cementing record.
Surface Restoration
Concrete cellars must be removed from the well site or filled with
earth. Well locations must be graded and cleaned of equipment, trash,
and other wastes, and returned to as near a natural state as possible.
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Sumps must be filled with earth after removal of harmful materials, and
the surface should be graded and revegetated. Unstable slope conditions
created as a result of project operations must be corrected.
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CHAPTER VIII
CONCLUSIONS
There is no record of significant damages, danger, or risks
to human health and the environment resulting from the
exploration, development, and production of geothermal energy.
Geothermal operations are regional by nature; however, the
bulk of the activities are confined to California.
Existing regulations appear to be effective in protecting
human health and the environment.
There is no indication that additional Federal regulations
are necessary.
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CHAPTER IX
RECOMMENDATIONS
EPA recommends that Subtitle C regulations not be applied to
geothermal wastes. Further, at present, the Agency sees no need for
additional regulations under Subtitle D.
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APPENDIX A
DATA MANAGEMENT
An extensive literature search was conducted to obtain data for this
study. Raw data from this literature search were loaded into a
computerized data management program that automatically flagged areas
where information was lacking or deficient. State and Federal agencies,
universities, and selected authors were then contacted to obtain the
required information. The result of these efforts produced a pool of
information that provided the necessary bases for estimating geothermal
waste volumes. Since waste volumes could not be extracted directly from
the literature, the information in the data base was critical to
calculations leading to estimation of waste volumes.
The data sources that provided input to the data base are listed
below.
DATA SOURCES
Acurex. 1983. Analysis of geothermal wastes for hazardous components.
Cincinnati, Ohio: U.S. Environmental Protection Agency Industrial
Environmental Research Lab.
Bloomquist, R.G. 1985. Evaluation and ranking of geothermal resources for
electrical generation or electrical offset in Idaho. Montana, Oregon
and Washington. Vols. I-III. Portland, Oregon: Bonneville Power
Administration, U.S. Department of Energy.
California Division of Oil and Gas. 1983a. Geothormal hotline
Vol. 13, No. 1.
. 1983b. Geothermal hotline. Vol. 13, No. 2.
. 1984. Geothermal hotline. Vol. 14, No. 2.
. 1985a. Geothermal hotline. Vol. 15, No. 1.
. 1985b. Geothermal hotline. Vol. 15, No. 2.
. 1986. Geothermal hotline. Vol. 16, Nos. 1 and 2.
A-l
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. 1987. Geohot computer printout: Total State production and
injection, 1982-1986. Retrieved January 27, 1987.
Cosner, S.R., and Apps, J.A. 1978. A compilation of data on fluids from
geothermal resources in the United States. U.S. Department of Energy.
DiPippo, R. 1985. Worldwide geothermal power development. EPRI Annual
Geothermal Meeting in San Diego, California, June 1985.
Ellis, P., and Conver, M. 1981. Material selection guidelines for
qeothermal energy utilization systems. DOE/RA/27026-1.
Geological Survey Circular 790. 1978. Assessment of geothermal resources
of the United States--1978. In cooperation with U.S. Department of
Energy.
Geological Survey Circular 892. 1982. Assessment of geothermal resources
of the United States--1982. In cooperation with U.S. Department of
Energy.
Geonomic. 1978. Geothermal environmental impact assessment: subsurface
environmental assessment for four qeothermal systems. NTIS PB-300
851. Cincinnati, Ohio: U.S. Environmental Protection Agency,
Environmental Monitoring and Support Laboratory.
Goering, S.W., et al. 1984. Direct utilization of qeothermal energy for
Paqosa Springs, Colorado. U.S. Department of Energy, Division of
Geothermal and Hydropower Technologies.
Greene, R. (Undated). Geothermal well drilling and completion. Handbook
of qeothermal energy.
Harding-Lawson Associates. 1979. Geothermal impact assessment: ground
water monitoring guideline for geothermal development. Las Vegas,
Nevada: U.S. Environmental Protection Agency, Environmental
Monitoring and Support Lab.
Hooper, G. 1987. Geothermal electric power plants operational in the
United States. U.S. Department of Energy.
Kroopnick, R.W. 1978. Hydrology and geochemistry of an Hawaiian
geothermal system: HGP-A. National Science Foundation/Energy
Research and Development Agency.
Lawrence Berkeley Laboratory. 1986. Case studies of low to moderate
temperature hydrothermal energy development. U.S. Department of
Energy, Idaho Operations Office.
A-2
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Lienau, L.J. 1986. Status of direct heat projects in western States.
GHC Bulletin. Fall 1986, pp. 3-7.
Meridian. 1985. Directory of direct heat geothermal pro.iects in the
United States. U.S. Department of Energy, Division of Geothermal and
Hydropower Technologies.
Morton, R.E. 1986. Imperial Valley and The Geysers geothermal area trip
report to Bob Hall, U.S. Environmental Protection Agency, Office of
Solid Waste, December 16, 1986.
O'Banion, K., and Layton, D. 1981. Direct use of hydrothermal energy:
review of environmental aspects. U.S. Department of Energy Office of
the Assistant Secretary for Environmental Safety and Emergency
Preparedness.
Reed, M.J. (Undated). Selected low temperatures (less than 90°C)
geothermal systems in the United States. Reference data for U.S.
Geological Survey Circular 892. Open-file report 83-250.
Royce, B.A. 1985. Impact of environmental regulations on the safe
disposal of qeothermal wastes. Upton, New York: Department of Applied
Science, Brookhaven National Laboratory.
Schultz, I.E. 1985. Recovering zir.c-leaJ sulfide from a qeothermal brine.
U.S. Department of Interior, Bureau of Mines R18922. Washington,
D.C.: U.S. Government Printing Office.
U.S. Department of Energy. 1980a. Environmental assessment, geothermal
energy, Heber geothermal binary-cycle demonstration project, Imperial
County, California.
. 1980b. State of the art of liquid waste disposal for
qeothermal energy systems, DOE/EV-0083.
Varnado, S.G., et al. 1981. Geothermal energy. Geotimes, February 1986,
pp. 25-27.
Varnado, S.G., and Maish, A.B. 1948. Geothermal drilling research in the
United States: alternative energy sources II.
Williams, T. 1986. U.S. Department of Energy comments on the Technical
Report, Wastes from exploration, development and production of crude
oil, natural gas and geothermal energy: an interim report on
methodology for data collection and analysis.
Zimmerman, R.E. 1984. Environmental technology for qeothermal energy.
Idaho Falls, Idaho: U.S. Department of Energy.
A-3
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APPENDIX B
ABBREVIATION OF UNITS AND SCIENTIFIC TERMS USED
IN THE FIGURES AND TABLES
BGY Billions of gallons per year
g/cnr Grams per cubic centimeter
kg Kilogram
km Kilometer
MGD Millions of gallons per day
Al Aluminum
Alk Alkalinity
As Arsenic
B Boron
Ba Barium
BaSO^ Barium sulfate
Be Beryllium
Ca Calcium
Cd Cadmium
Cl Chlorine
Cr Chromium
Co Cobalt
Cu Copper
CuS Copper sulfide
F Fluorine
Fe Iron
H2S Hydrogen sulfide
Hg Mercury
Zn Zinc
IDS - Total Dissolved Solids
mg/L
MW
ug/L
pCi/g
pCi/s
Li
Mg
Mn
Mo
Na
Ni
Pb
Rb
S
Sb
Se
Si
Si02
Sn
S04
Sr
Ti
V
Milligrams
Megawatts
Micrograms
PicoCuries
PicoCuries
Lithium
Magnesium
Manganese
Molybdenum
Sodium
Nickel
Lead
Rubidium
Sul fur
Antimony
Selenium
Sil icon
Sil icon di
Tin
Sulfate
Strontium
Titanium
Vanadium
per liter
per liter
per gram
per second
oxide
TSS - Total Suspended Solids
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APPENDIX C
GLOSSARY
Annul us: The space between the well casing and borehole wall or
between different well casing strings.
Barrel: A measure of volume. One barrel is the equivalent of
42 U.S. gallons or 0.15899 cubic meters. One cubic meter equals 6.2897
barrels.
Binary Process: A geothermal conversion process that uses a
secondary working fluid with a boiling point less than that of water. In
this process, heat from the geothermal brine is transferred to the
working fluid by a heat exchanger; the working fluid is vaporized, then
used to power the turbine generator. The brine and working fluid are in
separate closed loops. The geothermal fluid is maintained in the liquid
state by high pressure, and is injected into the reservoir after use.
Brine: An aqueous solution containing a higher concentration of
dissolved solids than ordinary seawater (i.e., greater than 35,000 mg/L,
or 3.5 percent).
Casing: Steel pipe placed in oil, gas, and geothermal wells as
drilling progresses, to prevent caving in of the borehole wall. Casing
also provides a means of fluid extraction if the well is productive.
Condensation: The process by which a gas is transformed to a liquid
(the liquid is called the condensate) by cooling or an increase in
pressure or both, simultaneously.
Condensable Gas: Gas that can be reduced to a denser form, as from
steam to water.
Conductor Pipe: Surface pipe used in wells to seal off near-surface
water, prevent caving in of borehole walls, and serve as a conductor of
drilling mud through shallow, unconsolidated layers of sand, silt, and
clay.
Cooling Tower Slowdown: The removal of liquids or solids from a
cooling tower process vessel or line by the use of pressure.
Cooling Tower Drift: A fine mist of water droplets that escape from
the top or sides of the tower during normal operation. Any compound
normally present in the circulating water will be carried out with the
drift.
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Derrick: A wooden or steel structure built over a well site to
support drilling equipment, and a tall mast for raising and lowering
drill pipe and casing.
Direct Use Geothermal System: The use of geothermal energy as heat
without converting it to another form of energy.
Drill Bit: The tool attached to the lower end of drill pipe for
gouging, tearing, grinding, and cutting rock formations in drilling oil,
gas, and geothermal wells. Drilling mud is pumped through the tool for
cooling and circulation.
Drill Cuttings: Fragments of rocks dislodged by the action of the
drill bit and brought to the surface by the circulation of drilling mud.
Drill Stem: All members in the assembly used for drilling by the
rotary method from the swivel to the bit, including the kelly, drill pipe
and tool joints, drill collars, stabilizers, and various subsequent items.
Drill String: The column, or string, of drill pipe with attached
tool joints that transmits drilling fluid and rotational power from the
kelly to the drill collars and bit.
Drilling Mud: A special mixture of clay, water, and chemical
additives pumped down the well bore during rotary drilling and workover
operations. The mud brings drill cuttings to the surface, cools and
lubricates the bit and drill system, protects against blowouts by
controlling subsurface pressures, and deposits a coating on the borehole
wall to prevent the loss of fluids to the formations penetrated.
Effluent: An outflow of treated or untreated liquid waste from an
industrial facility or from a holding structure, such as a pit or pond.
Extraction Procedure: A solid waste exhibits EP toxicity (EP) if,
using the test methods described in 40 CFR or equivalent methods approved
by the Administrator, the extract from a representative sample contains
any of the contaminants listed in 40 CFR 261.24, Table I, at a
concentration equal to or greater than the value given for that waste in
the table. If the waste contains less than 0.5 percent filterable
sol ids,.the waste, after filtering, is considered to be the extract.
If a solid waste exhibits EP toxicity but is not listed as a hazardous
waste in 40 CFR, Subpart 0, an EPA hazardous waste number that
corresponds to the toxic contaminant causing it to be hazardous will be
assigned.
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Filter Cake: The compacted solid or semisolid material separated
from a liquid and remaining on a filter after pressure filtration; the
plastic-like coating of solids from the drilling fluid that adhere to and
build upon the borehole walls and are left behind.
Flash Process: Partial evaporation of hot condensed liquid by a
stepwise reduction in system pressure; vaporization of volatile liquids
by either heat or vacuum.
Flocculation: Aggregation or coalescence of fine particles to form a
settled, filterable mass.
Fly Ash: Fine solid particulate, essentially on combustible refuse.
Fly ash is carried by draft out of a bed of solid fuel and deposited in
isolated spots within a furnace or flue, or carried out through a chimney.
Forced Air System: A space heating system where hot air is blown
from a heat source, then distributed by ducts to outlets.
Freon: A trade name used for any of various nonflammable gaseous and
liquid fluorinated hydrocarbons used as refrigerants and as aerosol
propel 1 ants.
Fumarole: A hole or vent from which fumes or vapors are emitted; a
spring or geyser that emits steam or gaseous vapor; usually found in
volcanic areas.
Geophysical Survey: The exploration of an area in which geophysical
properties and relationships unique to the area are mapped by one or more
geophysical methods may include: electrical resistivity, infrared, and
magnetotelluric surveys, as well as heat flow and seismic monitoring.
Geopressured Geothermal System: Hot, high-pressure brines containing
dissolved natural gases. A potential hybrid energy resource of
mechanical, geothermal, and chemical energy.
Geothermal Gradient: The change of the earth's temperature with
increasing depth, expressed in degrees per unit depth, or in units of
depth per degree. The average gradient is approximately 1°C/30 m
(2°F/100 ft).
Geyser: A type of hot spring from which columns of hot water and
steam gush into the air at more or less regular intervals.
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Hot Dry Rock: Nonmolten, essentially nonporous, impermeable, hot
rocks with above normal geothermal gradients. Water injected into
manmade fractures is expected to return steam and/or hot water through a
second well for economic recovery of geothermal energy.
Hot Spring: A spring with a temperature above that of the human body
(98'F).
Hydrocyclone: A device that separates granular solids from a stream
of water. The stream takes a circular path in a conical vortex where
centrifugal forces act to separate the stream into a coarse fraction,
which is discharged at the apex, and a fine fraction, which is removed by
the vortex finder.
Hydrogen Sulfide (H2S): A flammable, toxic, colorless gas with an
offensive odor, commonly produced from "sour" gas wells and some
geothermal wells, and emitted from volcanic vents.
Hydronic System: A space heating system that uses hot water directly
in radiant panels, convectors, or radiators, either singly or in
combination with one another.
Igneous Rock: Rock solidified from hot, mobile material called
magma. Examples are granite, andesite, and basalt.
Kelly: The heavy square or hexagonal steel pipe suspended from the
swivel through the rotary table, and connected to the topmost joint of
drill pipe to turn the drill stem and ultimately the drill bit, as the
rotary table turns. It has a bored passageway that permits fluid to be
circulated into the drill stem and up the annulus, or vice versa.
Kelly Bushing: A special device that, when fitted into the master
bushing, transmits torque to the kelly and simultaneously permits
vertical movement of the kelly to make a hole. It may be shaped to fit
the rotary opening or have pins for transmitting torque, and is rotated
by power from the drawworks and drilling engines.
Kiln: A large furnace for baking, drying, or burning firebrick or
refractories, or for calcining ores or other substances.
Lava: The fluid rock that issues from a volcano or a fissure in the
earth's surface; such rock when solidified upon cooling.
Leachate: A liquid that percolates through soil, sand, or other
media, usually migrating from a pit or landfill.
Liquid-Dominated Geothermal System: A subsurface reservoir of hot
water or a mixture of liquid and vapor.
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Magma: A naturally occurring mobile rock material generated within
the earth and capable of intrusion and extrusion. Igneous rocks are
thought to have been derived from magma through solidification.
Mud Pot: Type af hot spring consisting of a shallow pit or cavity,
containing hot, generally boiling mud, carrying very little water and a
large amount of fine-grained mineral matter. Commonly associated with
geysers and other hot springs in volcanic areas. These features vary in
size (some attain 30 feet in diameter) and depth to mud level (some
attain 15 feet).
Mud Volcano: A cone-shaped mound of mud, built around a spring,
brought to the surface by slowly escaping natural gas of volcanic,
petroliferous, or other origin. These features may attain a height of
250 feet.
Nitrogen Drilling: A drilling technique using nitrogen as the
drilling fluid. It is used in drilling vapor-dominated geothermal
systems to avoid damaging the production zone with hydrostatic columns of
mud or water. Nitrogen is preferred to air, because the oxygen in air
can promote corrosion.
Permeability: The capacity of a porous rock, sediment, or soil to
transmit fluid; a measure of the rate at which, under unequal pressures,
a fluid of standard viscosity can move a given distance over a given time
interval.
pH: The negative logarithm of the hydrogen ion activity; the degree
of acidity or basicity of an aqueous solution. At 25°C, 7 is the
neutral value; acidity increases with the decreasing value below 7 and
basicity increases with increasing value above 7.
Polymerization: The joining together of two or more molecules to
form a single, heavier molecule.
Precipitation (Chemical): The chemical process of bringing dissolved
and suspended particles out of solution; producing a separable solid
phase in a liquid medium.
Producing Horizon: The subsurface zone or stratum that will produce
fluid (aqueous, petroleum, or geothermal) when penetrated by a well.
Quad: Unit of heat energy, equal to one thousand trillion British
Thermal Units.
C-5
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Remote Sensing: The gathering and recording of information about
some property of an object or area by a recording device that is not in
actual physical contact with the object or area being studied.
Reserve Pit: An excavation connected to the working mudpits of a
drilling well in which excess muds and other drilling fluids are stored;
a standby pit containing already-mixed drilling mud for use in an
emergency when extra mud is needed; or an excavated earthen-walled pit
used for wastes.
Rotary Drilling: A drilling method in which a hole is drilled by a
rotating bit to which a downward force is applied. The bit is fastened
to the drill stem, and rotated by power transmitted to the rotary table
on the derrick floor.
Rotary Table: The geared rotating table to which power is
transmitted, which turns the kelly, drill stem, and bit assembly.
Salinity: A measure of the quantity of total dissolved solids in
water, usually expressed by weight in parts per thousand or parts per
million (ppm).
Sand Trap: A device for separating heavy, coarse particles from the
cuttings-laden fluid overflowing a drill collar; a trap separating sand
and other particles from flowing water and generally including a means of
ejecting them.
Scale: A hard encrustation on the surface of downhole, wellhead, and
surface equipment formed by precipitation of dissolved and suspended
solids.
Scrubbing: The process of using extracting liquids to separate
soluble gases.
Sedimentary Rock: Rock formed by the accumulation of sediments in
water or from air. Layered structure is characteristic. Examples are
shale, sandstone, and limestone.
Shale Shaker: A series of vibrating trays with sieves that remove
rock cuttings from the circulating drilling fluid in a rotary drilling
operation.
Sludge: A residue from air, wastewater, or other residues from
pollution control.
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Sulfur Dioxide: A toxic, irritating, colorless gas or liquid
compound formed by the oxidation of sulfur. It dissolves in water to
form sulfurous acid.
Supercritical: Property of a gas that is above its critical pressure
and temperature, and which makes it impossible to liquify, regardless of
the amount of pressure applied.
Surface Runoff: Water that travels over the soil surface to the
nearest surface stream; the runoff of a drainage basin that has not
passed beneath the surface since precipitation.
Swivel Head: An assembly at the top of the kelly that allows free
rotation of the kelly while not transferring rotation to the mud hose and
hoist cables.
Total Dissolved Solids (IDS): The total content of suspended and
dissolved solids in a solution.
Vapor-Dominated Geothermal System: A subsurface reservoir containing
predominantly high-temperature steam and gases.
Viscosity: The resistance of liquids, semisolids, and gases to
movement or flow.
Volcano: A vent in the earth's crust through which molten rock
(lava), rock fragments, gases, and ashes,-are ejected from the earth's
interior. A mountain formed by the materials ejected.
C-7
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APPENDIX D
REPORT BIBLIOGRAPHY
Acurex. 1980. Identification of solid wastes in geothermal operations.
Final draft report to the EPA Technical Project Monitor. Cincinnati,
Ohio.
Acurex. 1983. Analysis of geothermal wastes for hazardous components.
Cincinnati, Ohio: Industrial Environmental Research Lab.
Armistead, C.H. 1983. Geothermal energy: its past, present and future
contribution to the energy needs of man. 2d ed. London: E&FN Span.
Bufe, C.G. 1982. Geothermal energy. Geotimes, February 1982, p. 37-39.
California Division of Gas and Oil 1983. Geothermal hotline Vol. 13,
No. 1.
. 1984. Geothermal hotline Vol. 14, No. 1.
. 1985a. Geothermal hotline Vol. 15, No. 1.
. 1985b. Geothermal hotline Vol. 15, No. 2.
. 1986. Geothermal hotline Vol. 16, Nos. 1 and 2.
. 1987. Geohot computer printout: total state production and
injection, 1982-1986. Retrieved January 17, 1987.
Chilinger, G.V., et al. 1982. The handbook of geothermal energy.
Houston: Gulf Publishing Co.
DiPippo, R. 1986. Geothermal power plants: Worldwide status.
. 1986. Geothermal Resources Council Bulletin, 15(11):9-18.
. 1985. Worldwide geothermal power development. EPRI Annual
Geothermal Meeting. San Diego, California.
Fairchild, D.M. 1985. National conference on disposal of drilling wastes.
D.M. Fairchild, ed. Norman: University of Oklahoma.
Fairchild, D.M., and Knox, R. 1985. A case study of off-site disposal
pits in McCloud, Oklahoma. National Conference on Disposal of
Drilling Wastes. D.M. Fairchild, ed. pp. 47-67. Norman: University
of Oklahoma.
D-l
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Geonomic. 1978. Geothermal environmental impact assessment: subsurface
environmental assessment for four qeothermal systems. NTIS PB-300
851. Cincinnati, Ohio: U.S. Environmental Protection Agency,
Environmental Monitoring and Support Lab.
Goering, S.W., et al. 1984. Direct utilization of qeothermal energy for
Paaosa Springs. Colorado. U.S. Department of Energy, Division of
Geothermal and Hydropower Technologies.
Hansen, P.N., and Jones, F.V. (undated). Mud disposal, an industry
perspective (received from IMCO Services by RCRA docket, December 15,
1986).
Hochstein, H.P. 1982. Introduction to qeothermal prospecting. Auckland,
New Zealand: Geothermal Institute, University of Auckland.
Lienau, L.J. 1986. Status of direct heat projects in western states."
GMC bulletin. Fall 1986, pp. 3-7.
McDonald, W.J., et al. 1978. Improved geothermal drilling fluids.
Geothermal Resources Council Transaction, Vol. 2.
Morris, W.F., and Stephens, F.B. 1981. Characterization of qeothermal
solid wastes. U.S. Department of Energy.-
Morton, R.E. 1986. Imperial Valley and The Geysers: geothermal area trip
report to Bob Hall, U.S. Environmental Protection Agency, Office of
Solid Waste.
Morton, R.E. 1987. Salton Sea and The Geysers geothermal area trip
report to Bob Hall. U.S. Environmental Protection Agency, Office of
Solid Waste.
O'Banion, K., and Layton, D. 1981. Direct use of hydrothermal energy:
review of environmental aspects. U.S. Department of Energy, Office
of the Assistant Secretary for Environmental Safety and Emergency
Preparedness.
Rafferty, J. 1985. Recommended practices for the reduction of drill site
wastes. National Conference on Disposal of Drilling Wastes. B.M.
Fairchild, ed. pp. 35-46. Norman: University of Oklahoma.
Reed, M.J. 1981. Geothermal energy. Geotimes, February 1981, pp . 35-36.
(Unpublished). Selected low-temperature (less than 90°C)
geothermal systems in the United States. Reference data for U.S.
Geological Survey Circular 892, open-file report 83-250.
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Robinson, J. 1987. Unocal docket No. F-86-OGRN-FFFFF.
Royce, B.A. 1985. Impact of environmental regulations on the safe
disposal of geothermal wastes. Upton, New York: Department of
Applied Science, Brookhaven National Laboratory.
Tucker, B. 1985. Soil applications of drilling wastes. National
Conference on Waste Disposal of Drilling Wastes, B.M. Fairchild, ed.
pp. 102-112. Norman: University of Oklahoma.
U.S. Department of Energy. 1980a. Environmental data - Energy technology
characterization. Washington, D.C.: U.S. Department of Energy Report
DOE/EV-0077.
1980b. Environmental assessment, qeothermal energy. Heber
Geothermal Binary-Cycle Demonstration Pro.iect. Imperial County,
California.
USEPA. 1987. U.S. Environmental Protection Agency, Office of Solid
Waste. Onshore oil and gas and qeothermal energy exploration.
development, and production: Human health and environmental risk
assessment. Washington, D.C.: U.S. Environmental Protection
Agency.
U.S. Geological Survey Circular 790. 1978. Assessment of geothermal
resources of the United States. In cooperation with the U.S.
Department of Energy. Washington, D.C.: U.S. Government Printing
Office.
Varnado, S.G., et al. 1981. Geothermal drilling and completion technology
development program plan.
Wallace, R.H., Jr. 1986. Geothermal energy. Geotimes 31(2):25-27.
Wallace, R.H., Jr., and Schwartz, K.L. 1987. Geothermal energy. Geotimes
32(2):28-29.
Williams, T. 1986. Department of Energy comments on the technical report
"Wastes from exploration, development and production of crude oil,
natural gas and geothermal energy: An interim report on methodology
for data collection and analysis."
Zimmerman, R.E. 1984. Environmental technology for qeothermal energy.
Idaho Falls, Idaho: U.S. Department of Energy.
D-3
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