EPA
United States
Environmental Protection
Agency
Office of
Research and
Development
Industrial Environmental Research
Laboratory
Cincinnati, Ohio 45268
EPA-600/7-77-085
August 1977
;
ENVIRONMENTAL IMPACT
STATEMENT FOR A
HYPOTHETICAL 1000 MWe
PHOTOVOLTAIC SOLAR-
ELECTRIC PLANT
Interagency
Energy-Environment
Research and Development
Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1 Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7 Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161
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EPA-600/7-77-085
August 1977
ENVIRONMENTAL IMPACT STATEMENT FOR A HYPOTHETICAL
1000 MWe PHOTOVOLTAIC SOLAR-ELECTRIC PLANT
by
D. Richard Sears
Donald V. Merrlfield
Morris M. Penny
Lockheed Missiles & Space Company, Inc.
Huntsville Research & Engineering Center
Huntsville, Alabama 35807
W. Glen Bradley
Environmental Consultants, Inc.
Las Vegas, Nevada 89109
Contract No. 68-02-1331
Project Officer
Robert P. Hartley
Power Technology and Conservation Branch
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial Environmental Re-
search Laboratory, U.S. Environmental Protection Agency, and approved for
publication. Approval does not signify that the contents necessarily reflect
the views and policies of the Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
The project discussed herein is hypothetical. No plans to install a
similar solar generating station anywhere are known to exist. The desig-
nation of a specific site in this report does not imply that plans exist to
install a solar generating station at the site, or that any previously pub-
lished construction plans for the site have been revised or are being
considered for revision.
11
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FOREWORD
When energy and material resources are extracted, processed, con-
verted, and used, the related pollutional impacts on our environment and
even on our healt often require that new and increasingly more efficient
pollution control methods be used. The Industrial Environmental Research
Laboratory - Cincinnati (lERL-Ci) assists in developing and demonstrating
new and improved methodologies that will meet these needs both efficiently
and economically.
This report, while dealing with a hypothetical 1000 MW photovoltaic
central generating station, is nevertheless a serious attempt to present
what a real Draft Environmental Impact Statement for a real plant would
look like. Environmental and energy administrators, environmental re-
researchers, and local government officials in the U.S. Southwest will find
this report useful in appraising the problems, if any, that would accom-
pany construction of such a plant. It will help these personnel to perform
the necessary developmental research and prepare public responses in
anticipation of construction.
Further information on this subject may be obtained from the Power
Technology and Conservation Branch of the Energy Systems Environmental
Control Division.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
111
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ABSTRACT
This report constitutes an environmental impact statement (EIS) for a
hypothetical facility believed to be similar to the photovoltaic solar-electric
plants which will be built some day. All features of this EIS are produced in
conformity with the mandates of the National Environmental Policy Act
(NEPA), although socio-economic matters are somewhat de-emphasized.
The solar-electric plant is a 1000 MWe silicon photovoltaic plant em-
ploying 50,000 one-axis sun-tracking modules distributed over nearly 52
km ^ of desert terrain without any known potential productivity, near Las
Vegas, Nevada. The plant is supplied with three hours of battery storage
capacity. The chosen plant design is conservative; environmental effects
related to area of land disturbed may be regarded as worst-case estimates.
The estimated cost of this plant is $1.67 x 109.
The plant will not require any cooling water, steam water, or any other
process water. It will not require cooling towers or stacks. There will be
no effect on groundwater, no thermal pollution, no surface water pollution,
no nois.e pollution, and no effects on local historical, archaeological, and
cultural values.
The principal adverse environmental effects expected relate to de-
struction of soil and vegetation on 52 km^ of desert terrain. Re-vegetation
is expected to be very slow without human assistance. Mitigative measures
are discussed and proposed. Numerous animals will be displaced either
temporarily or permanently by the project as a direct or indirect conse-
quence of loss of vegetative cover and of human activity.
The visual impact of this project will be extensive. Some persons will
regard the aesthetic impact as adverse, although others will regard the plant
as a tourist attraction.
This report was submitted in fulfillment of Contract No. 68-02-1331 by
Lockheed Missiles & Space Co., under the sponsorship of the U.S. Environ-
mental Protection Agency. This report covers a period from 4-1-76 to 7-
31-76 and work was completed as of 7-31-76. Editorial revisions were in-
corporated during February 1977.
IV
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EXECUTIVE SUMMARY
HYPOTHETICAL SOLAR-ELECTRIC PLANT
DRY LAKE VALLEY, CLARK COUNTY, NEVADA
(X) DRAFT ( ) FINAL ENVIRONMENTAL STATEMENT
RESPONSIBLE OFFICE: None
1. NAME OF ACTION: (X) ADMINISTRATIVE (Hypothetical)
2. DESCRIPTION OF ACTION: This Draft Environmental Impact State-
ment was prepared for the Environmental Protection Agency to assist
the Agency in its efforts to strengthen its inputs to and review of
Environmental Impact Statements in the area of new energy develop-
ments. This document has no legal significance. The "proposed
action" is entirely hypothetical. The specific site was chosen only
because extensive baseline data for it had already been collected in
preparation for performing an environmental assessment of a 2000
MW coal-fired plant actually proposed for construction at the site.
C
This Hypothetical Solar-Electric Plant is a 1000 MWe (peak) silicon
photovoltaic plant employing 50,000 one-axis sun-tracking modules
distributed over nearly 52 km.2 of desert terrain without any known
potential productivity, near Las Vegas, Nevada. The plant is to be
supplied with 3 hours of battery storage capacity. With unlimited
storage, the capacity factor could approach 100%; the limited storage
corresponds to a capacity factor of less than 50% in conventional
terms.
3. (A) ENVIRONMENTAL IMPACTS: The proposed station would:
(i) Provide 1000 MWe (peak) of electric power to meet the projected
power demands of customers in Nevada and Southern California.
(ii) Increase the reserve margin of the electric generating
capacity of the U.S. Southwest thereby improving the utility
industry's reliability and, secondarily, that of the associated
Interpool Network.
(iii) The plant will occupy about 52 km2 in Dry Lake Valley,
32 km NE of Las Vegas, Nevada. It will cost $1.67 x 109.
(iv) Construction would be phased over 10 years with portions
of the installation going on-line as they are completed. Plant
lifetime is estimated to be about 30 years, with phased de-
commissioning to occur over an additional 5 years.
V
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(v) A construction labor force of about 1000 employees is
expected. Only fifty operating personnel are planned.
(vi) The plant will not require any cooling water, steam
water, or any other process water. It will not require
cooling towers or stacks.
(vii) The effects on regional demographic, socioeconomic,
and community characteristics will in general be small and,
be overwhelmed by the effects of very rapid projected growth
in the Las Vegas urban areas.
(viii) There will be no effect on groundwater, no thermal
pollution, no surface water pollution, no noise pollution,and
no effects on local historical, archaeological, and cultural
values.
(B) ADVERSE ENVIRONMENTAL IMPACTS:
(i) The principal adverse environmental effects expected relate
to destruction of soil and vegetation on 52 km2 of desert terrain.
Re-vegetation is expected to be very slow without human assist-
ance. Mitigative measures are discussed and proposed.
(ii) Numerous animals will be displaced either temporarily or
permanently by the project as a direct or indirect consequence of
loss of vegetative cover and of human activity. Only the Desert
Tortoise requires assistance in relocation.
(iii) No endangered or threatened species are further threatened
by this project. The Kit Fox and the Desert Tortoise are both on
the Nevada list of endangered or threatened species. However,
the Kit Fox will relocate without assistance. The Desert Tortoise
is not rare or threatened in this region except in urban areas
and near highways. Nevertheless individuals would be destroyed
were no efforts made to relocate them outside the perimeter.
(iv) The visual impact of this project will be extensive. Some
persons will regard the aesthetic impact as adverse, although
others will regard the plant as a tourist attraction. No
mitigative measures are known to minimize the visual impact
at the proposed site, adjacent to U.S. Highway 93 and Interstate
Highway 1 5.
4. ALTERNATIVES TO THE PROPOSED ACTION:
(A) No action
(B) Large power import into the region
(C) Reactivation or upgrading of older plants
(D) Alternative sites
(E) Alternative sources of power (coal fired, nuclear, hydro,
advanced)
(F) Closer packing of solar modules
(G) Other solar options
(H) Storage options (none, lead-acid, pumped hydro, hydrogen cycle)
vi
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CONTENTS
Foreword iii
Abstract iv
Executive Summary , ' v
Figures xiii
Tables xiv
Acknowledgments xvi
1. Description of the Proposed Action 1-1
1.1 Summary 1-1
1.2 The Installation 1-4
Description of the Plant Design 1-4
Maintenance Facility and Philosophy 1-28
Central Headquarters Facility 1-30
Communications Facilities 1-30
Transmission Lines 1-31
Visitor Center and Visitor Control 1-31
Water Supply and Sewerage 1-32
Transportation Facilities 1-33
Plant Security 1-34
1.3 Project Schedule 1-34
1.4 Project Cost 1-35
1.5 Permits and Regulations 1-38
Permits 1-38
Clark County Regulations 1-38
State of Nevada 1-43
Federal Regulations 1-46
1.6 References 1-51
2. Environmental Setting Without the Project 2-1
2.1 Location 2-1
2.2 Regional Demographic, Socioeconomic, and Com-
munity Characteristics 2-3
Historic Population and Population Projections .... 2-3
Employment Characteristics and Labor Force
Inventory 2-4
Family Income 2-6
Vll
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Community Infrastructure 2-6
Education '.'.'.'.'. 2~9
Hospital Facilities 2-9
Transportation 2-11
Electrical Energy 2-12
Other 2-12
2.3 Water Resources, Use and Quality 2-13
Supply and Use •• 2-13
Surface Water 2-17
Groundwater 2-17
2.4 Sanitation and Waste Management 2-21
Wastewater Treatment 2-21
Solid Waste 2-22
2.5 Land Use 2-23
2.6 Geology and Hydrology 2-27
Geology • 2-27
Local Geology 2-27
Geology of Recommended Site 2-29
Seismology 2-30
Earthquake History 2-30
Foundation Considerations 2-32
Regional Hydrology 2-33
2.7 Climatology, Meteorology, and Air Quality 2-35
Data Collection 2-35
General Climatological Description 2-35
Stability Climatology 2-39
Meteorology 2-40
Surface Meteorology 2-40
Radiation " 2-40
Relative Humidity 2-41
Air Quality and Visibility 2-41
2.8 Ambient Noise 2-42
2.9 Ecological Setting Z-43
Description of Region 2-45
Biotic Associations of Southern Nevada 2-46
Tropic Relationships 2-52
Community Succession 2-54
Biotic Associations of the Solar Electric Station
Study Area 2-54
Vegetation 2-55
Vertebrates 2-56
Concluding Remarks 2-59
2.10 Archaeological and Historical Sites and National
Landmarks 2-60
Archaeology 2-60
viii
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Literature and Record Search .............. 2-61
Field Surveys 2-61
Testing Technique 2-61
Results 2-62
History 2-62
National Landmarks 2-63
Conclusions 2-63
2.11 Visual Values 2-63
2.12 References 2-63
3. Relationship of the Proposed Action to Land Use Plans,
Policies, and Controls for the Affected Area 3-1
3.1 Clark County Regional Planning Council 3-1
3.2 Bureau of Land Management Plan 3-1
Off-Road Competition 3-1
Sewage Effluent Lagoon 3-2
Power Transmission Corridors 3-2
Power Plant Siting and Pipelines 3-2
Mining Claims 3-3
4, Probable Impact of the Proposed Action on the Environment. . . 4-1
4.1 Ecological Impacts 4-1
Terrestrial Impacts of Construction 4-1
Aquatic Impacts of Construction 4-9
Terrestrial Impacts of Operation . 4-10
Offsite Aquatic Impacts of Operation 4-11
Absence of Thermal Discharge Effects 4-11
Conclusions 4-11
4.2 Shading by Solar Modules 4-13
4.3 Thermal Pollution 4-18
4.4 Visual Effects 4-19
4.5 Atmospheric Emissions 4-20
4.6 Erosion 4-21
4.7 Water Quality and Supply 4-22
4.8 Land Use 4-22
4.9 Noise 4-22
4.10 Waste Disposal 4-23
4.11 Transmission Lines 4-23
4.12 Effects on Local Historic or Cultural Amenities 4-23
4.13 Effects on Local and Regional Demographic, Socio-
Economic, and Community Characteristics 4-23
Population Effects 4-23
Municipal Services 4-24
ix
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Manpower 4-24
Infusion of Capital 4-25
4.14 References 4-25
5. Alternative to the Proposed Action 5-1
5.1 General 5-1
5.2 No Action 5-2
5.3 Feasibility of Large Power Import 5-2
5.4 Reactivation or Upgrading Older Plants 5-2
5.5 Alternative Sites 5-2
5.6 Alternative Sources of Power Generation 5-3
General 5-3
Coal Fired-Steam Electric 5-4
Nuclear Power Generation 5-6
Hydroelectric Power Generation 5-6
Advanced Energy Sources 5-6
5.7 Closer Packing Density for Solar Modules 5-7
5.8 Other Solar Options 5-10
5.9 Storage Options 5-11
No Storage 5-11
Lead Acid Batteries 5-11
Pumped Hydro Storage 5-12
Hydrogen Cycle Storage 5-12
5.10 Conclusions 5-12
5.11 References 5-13
6. Probable Adverse Environmental Effects Which Cannot
be Avoided 6-1
6.1 Ecological Effects 6-1
6.2 Visual Effects 6-2
6.3 Lost Recreational Values 6-2
6.4 Socio-Economic Effects 6-3
6.5 Atmospheric Emissions 6-3
6.6 References 6-4
Mitigation of Avoidable Impacts 7-1
7.1 Ecological Impacts 7-1
Reestablishing Vegetation 7-1
Minimizing Impacts of Construction on Animal
Populations 7'-4
Conclusions 7-4
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7.2 Socio-Economic Impacts 7-5
7.3 Atmospheric Emissions . 7-5
7.4 References 7-5
8. Relationship Between Local Short-Term Use of Man's
Environment and the Maintenance and Enhancement
of Long-Term Productivity 8-1
8.1 Land Use Benefits 8-1
8.2 Decommissioning 8-1
8.3 Power Contribution 8-2
8.4 Tax Revenues 8-2
Property Taxes 8-2
Sanitation District Payments 8-2
8.5 Other Economic Benefits 8-3
Employment and Income 8-3
Other Financial Sectors 8-4
8.6 Costs 8-4
Incremental Community Services and Facility Costs. . 8-4
Environmental Costs 8-4
Recreational Costs 8-5
Mineral Extraction 8-5
8.7 Reference 8-5
9. Irreversible and Irretrievable Commitments of Resources
Involved in the Proposed Action 9-1
9.1 Silicon 9-1
9.2 Steel 9-1
9.3 Cement 9-1
9.4 Water 9-3
9.5 Coal „ 9-3
9.6 Lithium 9-3
9.7 Other 9-3
9.8 References 9-4
10. Interests and Considerations of Federal Policy Thought to
Offset the Adverse Environmental Effect 10-1
Secondary Impacts 11-1
11.1 Pollutional Effects of the Silicon Solar Cell
Manufacturing Industry 11-1
11.2 Socio-Economic Effects 11-2
11.3 Effects on Transportation Systems 11-2
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11.4 References 11-2
12. Coordination 12-1
Appendixes
A Conversion Factors A-l
B Glossary of Terms and Abbreviations B-l
XI1
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FIGURES
Number Page
1-1 Location of hypothetical proposed solar plant 1-2
1-2 Typical 2000 kW solar module group — one of 500 1-5
1-3 26 kW solar module concept 1-7
1-4 Switchyard and headquarters complex layout (Ref. 1-2) • • • • 1-11
1-5 Power conditioning module functional block diagram
(Ref. 1-2) 1-12
1-6 Power conditioning module layout {Ref. 1-2) 1-13
1-7 Battery building (Ref. 1-2) 1-14
1-8 Plant and power conditioning module operation as a
function of time of day (Ref. 1-2) 1-18
1-9 Alternate plant and power conditioning module operation
as a function of time of day (Ref. 1-2) 1-20
1-10 Regulator operational characteristics — P > P. (Ref. 1-2). . 1-23
1-11 Regulator operational characteristics — P = P. (Ref. 1-2) . . 1-24
1-12 Regulator operational characteristics — P < P. (Ref. 1-2) . . 1-25
2-1 Relationship of the plant site to topographic features 2-2
2-2 Projected population — Clark County, Nevada 2-5
2-3 Recorded seismic events in Southern Nevada and adjacent
portions of California, Utah, and Arizona (Ref. 2-1) 2-31
2-4 Rainfall depth, duration, and frequency curves 2-34
2-5 Location of meteorological stations surrounding the Dry
Lake site (cf. Table 2-15) 2-38
4-1 Module shadows and loci of shadow extrema for summer
solstice 4-14
4-2 Module shadows and loci of shadow extrema for winter
solstice 4-15
4-3 Module shadows and loci of shadow extrema for spring
and fall equinoxes 4- 16
5-1 Inter-module shadowing 5-9
Xlll
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TABLES
Number
1-1 Plant Cost Elements 1-36
1-2 Selected Air Quality Standards !-40
1-3 Pollution Concentration Conditions 1-42
1-4 OSHA Standards for Fugitive Dust 1-48
2-1 Historical Population 2-4
2-2 Labor Force, by Industrial Sector (Las Vegas SMSA —
1960, 1970, 1975) 2-7
2-3 Union Membership 2-8
2-4 Employment Projections, Las Vegas SMSA (1980-2000) . . . 2-8
2-5 School Capacity and Enrollment, Clark County School
District (1973-1974) 2-10
2-6 Projected School Building Needs, by Attendence
Area, Clark County School District 2-10
2-7 Electric Energy Usage 2-12
2-8 Water Uses and Supply Distributions — Las Vegas
Valley (1973) 2-14
2-9 Projected Distribution of Nevada's Allotment of Colorado
River Water (Acre Feet/Year) 2-15
2-10 Phase I Southern Nevada Water System Delivery
Commitments 2-15
2-11 Phase I: Southern Nevada Water System Delivery Options . . 2-16
2-12 Water Needs and Supply Distributions — Las Vegas (2000) . . 2-18
2-13 Groundwater Quality, Dry Lake Valley, Clark County,
Nevada 2-19
2-14 Average Monthly Precipitation and Temperature Values
at McCarran International Airport, Las Vegas, Nevada
(1937-1973), (Elevation 2162 ft MSL) 2-37
2-15 Summary of Surface Winds 2-38
2-16 Background Concentrations of Various Contaminants
in the Area of the Proposed Site 2-42
2-17 Ambient Noise Levels at Monitoring Locations
Surrounding Unit 1 2-44
xiv
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Number Page
4-1 Shadow Lengths for 34 Foot High Structure
at 34°N Latitude 4-18
5-1 Conditions for Inter-Module Shadowing 5-8
8-1 Estimated Property Tax Revenues from Proposed
Solar-Electric Station ($ Millions) 8-3
8-2 Incremental Community Costs for Services and Facilities . . 8-4
9-1 Steel Requirements for 50,000 Module Array 9-2
9-2 Steel Supply/Demand Data Compared with Station
Requirements 9-2
XV
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ACKNOWLEDGMENTS
The authors are particularly grateful to Mr. Gary Parker, USEPA
Region VIII, Denver; Dr. B0 W. Marshall, Sandia Laboratories, Albuquerque;
Mr. John W. Arlidge, Nevada Power Company, Las Vegas; and Dr0 F. T, C.
Bartels, Spectrolab, Inc., Sylmar, California,,
These persons supplied the basic documentation making possible the
entire effort, graciously granted permission for us to quote extensively
from the documents, and invested substantial time in furnishing us with
additional information beyond the documentation,
The project would have been very much more difficult without the
help offered by these individuals particularly, and also those listed in
the section entitled "Coordination."
xvi
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SECTION 1
DESCRIPTION OF THE PROPOSED ACTION
1.1 SUMMARY
The solar energy electrical power station is a hypothetical plant used
to assess the environmental impact of a utility size solar power station. The
site selected for the plant is typical of the sites currently envisioned for the
location of the first solar energy electrical power stations. This site is ap-
proximately 32 km northeast of Las Vegas, Nevada (Figure 1-1). A detailed
environmental assessment exists relative to the site and will be utilized ex-
tensively for background information in this report.
The station is a conceptual design for a photovoltaic plant with a 1000
MWe (peak) capacity. Operating with a capacity factor of 0.5 due to limited
energy .storage, the plant would produce approximately 0.88 x 10" MWh/yr.
The plant consists of 50,000 one-axis sun-tracking modules, each IT.lmlong,
8.5 m wide, and 10.4 m high and the ancillary equipment needed to interface
these arrays with a utility network. For visual perspective, one might com-
pare this generating station to a city of 50,000 small homes laid out on a
nearly perfect square grid of 33 m lot lines.
Major system components of the plant include the modules, power con-
ditioning facilities and a power wiring system. Major features associated
with the facility will be the switchyard, roads and railroad access, adminis-
tration buildings, storage buildings, maintenance building and a visitor center.
The land area required for the 1000 MWe plant is approximately 52 km or
5200 hectares.
Each module consists of an assembly of concentrating collectors and
silicon photovoltaic cells, and a framework supporting the optical and photo-
voltaic elements. Approximate weight for the module is 12.7 metric tons
1-1
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Figure 1-1. Location of hypothetical proposed solar plant.
1-2
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(MT)o The foundation for each is a 12.2 m concrete ring bearing a track
upon which the module runs during its daily tracking. The module rotates
only about a vertical axis to track the sun, in its westward motion. Each of
the 50,000 solar modules is capable of producing 20 kW under normal insola-
tion.
Power from 100 adjacent modules forms the input to each of 500 2 MW
power conditioning facilities. Each power conditioning facility includes a
regulator, inverter, battery and controller. The controller is governed by a
microcomputer that adjusts power output and battery charging and, by means
of an SCR switching regulator, tracks the 2 MW group's combined electrical
characteristics as a function of temperature and insolation to extract the
maximum power available from the arrays.
A 3 hour store of energy in a heated lithium/sulfur battery provides
power during periods of cloud cover or, as available, enables plant operation
into the early evening hours or early post-dawn morning hours. The dc out-
put of the solar cells (through the regulator) and battery is converted into a
60 Hz sinusoidal wave form compatible with the utility network. The inverter
can also be operated as a phase-controlled rectifier to accept and convert for
storage of off-peak utility ac energy off the grid. In addition to controlling
the operation of the power conditioning modules, the controller also controls
the array drive motors and multiplexes data for transmission to the plant's
central control room.
The administration buildings are centrally located within the facility
boundaries. These house the master control room and offices for facility
personnel. Storage buildings are provided for storage of array components,
batteries, etc., prior to installation or shipment to the manufacturer for re-
furbishment. A maintenance building will be utilized to effect repairs and
conduct routine maintenance procedures.
North-south service roads every 329 m within the facility will be uti-
lized to service the arrays. Road access to the site will be available via an
asphalt paved road from Interstate Highway 15, approximately 1.6 km east
1-3
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of the main entrance to the site. The site access road's junction with the
interstate highway is via a "four-leaf clover" arrangement. A visitor's
orientation and control center will be located near the interchange to provide
for visitor control. An overpass over the main railroad will be provided for
uninterrupted highway travel to and from the site.
Module structures will be delivered to the site by the Union Pacific
Railroad. A new rail spur will be constructed for this purpose.
No process water or cooling water is needed. Potable waters for per-
sonnel, and minimal quantities of water for maintenance are required. Solar
modules are not to be washed; therefore no piping is needed among modules.
Occasional washing down of battery house floors is conceivable but can be
accommodated by water truck. A chain link fence, barbed wire topped, will
enclose the facility. Capacitive probe systems (500) are connected to fence
sections for intrusion detection and alarm. Primary access is by gate on the
main road. Locked gates are located at selected remote locations.
A visitor control and orientation center is located outside the facility
boundaries. The purpose of this center is to provide the interested public
with information relative to the operation of the facility. This can include
lectures, demonstration models and guided tours of the facility.
1.2 THE INSTALLATION
Description of the Plant Design
The plant utilizes 50,000 power generating modules arranged in groups
of 100 modules each. Figure 1-2 depicts a conceptual view of a typical group.
Each group has a nominal capacity rating of 2.0 MW, and includes a central
power conditioning/storage module comprised of a power regulator, a bank of
storage batteries, power inverter, and control system. There are 500 groups
whose output is brought to a central plant switchyard by a 34 kV distribution
system. There the voltage is stepped up to 230 kV for connection to the
utility network by a transformer bank. All switchgear necessary for proper
operation of the system is included as well as instrumentation and control
1-4
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2 MW Output
Note: Module orientation is
shown for solar noon.
Figure 1-2. Typical 2000 kW solar module group - one of 500.
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systems and auxiliaries. (The control switching layout is described later
and illustrated in Figure 1-4.)
Solar Array Modules; The dominant feature of the plant is the large
array of identical power generating modules spaced on 32.9 m centers in a
NS-EW grid pattern, occupying approximately 52 km. . The design and
construction of these modules as given in the following pages is based largely
on a design concept prepared for Spectrolab Corporation by Ingenasu Asso-
ciates (Ref. 1-1). It is believed to be fairly typical of those future photo-
voltaic power plants which use optical concentration of sunlight.
Figure 1-3 shows a conceptual view of a typical 26 kW module. This
module is 8.5 x 17.1 m at the base, 10.4 m high overall, and weighs 12.7 MT.
It rotates about a single vertical axis to track the sun. It is equipped with 14
linear collector segments, each'made up of 1.2 x 12.2 m primary parabolic
trough concentrator and a 12.7 cm x 12.2 m absorber, with the segments
arranged side by side on a plane inclined 45 deg from the horizontal.
The primary concentrators are composed of 11 gage (3mm) sheet steel
bent into a parabolic trough and retained in this configuration by edge clamps.
The inside primary concentrator surfaces are covered with a special plastic
reflecting surface material. These reflecting surfaces are metallized second
surface reflectors composed of a plastic substrate (probably Scotchcal alum-
inized acrylic or Sheldahl Ag-fluorocarbon) attached to the concave steel
trough surfaces by adhesive applied to the metallized surface. No cover
glass is provided over the trough surfaces themselves.
The lifetime of this reflective surface is unknown. Photolytic and
thermal degradation of both the plastic substrate and of the adhesive are
possibilities which need investigation for two reasons;
1. Failure of these surfaces, requiring replacement of even a few
per month, would introduce an enormous maintenance and lo-
gistical problem. Field stripping of deteriorated plastic, solvent
wash to remove residual adhesive from the troughs, and field ap-
plication of new reflective material, seem to us to be quite im-
practical.
1-6
-------
Rotation
CD
Support
Wheel
(1 of 4)
Metal
Skirt
Concrete
Ring
Foundation
End View of
Reflector/
Absorber
Figure 1-3. 26 kW solar nodule concept.
1-7
-------
Selective removal and replacement of troughs is possible, but ad-
herence to configuration specifications (to retain desired optical
characteristics) would be very difficult.
We conclude that long-term integrity of the reflective surface is
one of the least proved elements of facility design. It ranks with
battery storage in this respect. However, as discussed later, the
facility can operate without storage, but not without reflectors.
These considerations seem to argue persuasively for sequential
plant construction, as described in Section 1.3. By bringing
earliest units on-line as they are complete, performance histories
may be compiled and used to upgrade design features on a dynamic
basis during plant construction. Slipped schedules due to such
actions would not affect the operation of units already functioning.
2. Degradation of plastic and adhesive has potential environmental
consequences which demand future assessment. Atmospheric
emissions and introduction of organic contaminants into run-off
water are two aspects. Identification of emissions and discharges
and transport modeling for this distributed source would have to
precede an evaluation of occupational hygiene effects, public health
effects, and ecological effects.
The absorber has a 6.1 cm x 12.20 m strip of silicon solar cells, contained
within a Winston-type concentrator with 12.2 cm aperture area. A cross-
section view of a typical segment is also shown in Figure 1-3. The absorber
(with solar'cells) is passively cooled using air convection and operates nom-
inally at 100 C. The total nominal peak output of the 14 segments is 26 kW.
The module is constructed almost entirely of steel, including the pri-
mary concentrators. The structure sits on four wheels which ride a 12.2 m
diameter circular rail supported by a concrete ring foundation. Horizontal
restraint is accomplished using a center column foundation and bearing 208
located at the center of the base of the module. The over-turning tendency
arising from high winds is resisted by a combination of the steel structure
weight, and the center column foundation. Water run-off from the 208 m2
inclined surface of the module is collected and channeled onto a gravel pad
inside the circular area beneath the module. As shown later (cf., Fig. 2-4,
the "100 year rain" in this area is about 6.4 cm, and this would occur over a
12-hour period. Therefore, it would be an extraordinary event were rain to
fall fast enough to collect inside the ring and flood the track and then freeze
and disable the tracking mechanism.
1-8
-------
Ice and snow collecting on the primary troughs would temporarily re-
duce or eliminate collection. The arrangement prevents soil erosion around
the module and places the water approximately where it normally would have
fallen. As shown in Figure 1-3, the module has a circular metal skirt at its
base to prevent build-up of airborne sand and dust near the support rail.
For sun-tracking, the module is equipped with a motorized mechanism
to rotate it by driving one rear wheel.
Foundation and Module Erection; The center column foundation is 92 cm
in diameter by 5.5 m below grade. The ring foundation is 46 cm wide and ex-
tends 61 cm below grade. Total concrete volume is 16 m per module, re-
quiring therefore, 0.80 x 10 m of concrete for the 50,000 module installation.
The modules will be mass produced at suitable industrial facilities and
shipped to the site by rail or truck for assembly and placement on the pre-
pared foundations. Foundation construction will proceed as follows; when
soil loosening and grading operations are completed, construction of the center
column proceeds. An auger drills a 92 cm diameter hole to a depth of 5.5 m
and a preformed reinforcing bar cage is lowered into place, followed by
formwork and concrete placement. The ring foundation is made ready with a
trenching operation, after which the concrete is placed and the rail is mount-
ed. The concrete will be obtained either from portable on-site batch plants
or from ready-mix plants near the solar power plant site. Availability of
cement does not appear to be a problem since there is a large Portland ce-
ment plant in the immediate vicinity, and numerous cement manufacturers
are located elsewhere in the region.
Powerplant Wiring: The overall wiring network brings power from the
solar modules to the plant site boundary and interconnects the major equip-
ment items. The power wiring network consists of four major areas: dc
buses, 34 kV distribution system, a switchyard and a 230 kV transmission
line. Station power and grounding systems are also included.
1-9
-------
The 34 kV, 60 Hz ac, three-phase distribution system includes all wiring
and components required for connection of each power conditioning module
power output terminal to the 34/230 kV switchyard input terminals on the two
34 kV line dead-end terminus structures.
The 230 kV transmission line system includes all wiring, components
and towers required for connection from the 34/230 kV switchyard dead-end
structure. Terminals and a 230 kV tower structure are located on the plant
boundary line, where continuation is by the utility, using the existing trans-
mission corridor and lines shown later in Figure 2-1. The switchyard is
shown in Figure 1-4.
With the exception of the large amount of distributed wiring to inter-
connect the 50,000 solar modules, the power wing is conventional in amount
and design. An environmental effect unique to a solar power plant is the
large amount of relatively small diameter module interconnect wiring placed
underground. This is not seen as a problem area.
Power Conditioning Modules; A typical power conditioning module
(PCM) consists of a power regulator, storage battery, dc-ac inverter, and a
controller. The PCM, of which there will be 500, is shown schematically in
Figure 1-5. The regulator, in conjunction with the controller's microcom-
puter, tracks the solar module characteristics for variations Ln solar input
and temperature to maximize power output from each solar module. The
input power to each regulator will be 2500 V x 1800 A. The regulator equip-
ment is in a portion of the inverter building and is located as shown in Figure
1-6. The regulator is air cooled using a portion of the inverter cooling sys-
tem.
The lithium/sulfur batteries will be located in a 3.7 x 16.8 m battery
building as shown in Figure 1-7. The building is all-steel construction, with
a 15 cm thick reinforced concrete floor.
Battery development is due to Argonne National Laboratory (Ref. 1-3).
The battery bank will be 2.4 x 12.2 x 3.1 m high with a nominal weight of 79 MT.
1-10
-------
&/////D
wuw.iw tor
/c\\\v\\\\s
Figure 1-4. Switchyard and headquarters complex layout (Ref. 1-2).
-------
I - POWER CONDITIONING MODULE •)
SOLAR
MODULE
1
SOLAR
MODULE
2
SOLAR
MODULE
100
*•
•*
" L_
REGULATOR
1
;ONTROLLEF
BATTERY
CONTROL
ROOM
(
J
ff~l
-V
34 KV
DISTRIBUTION
LINE
230 KV
TRANSMISSION
LINE
-11-
UTILITY
Figure 1 -5. Power conditioning module functional block diagram
(Ref. 1-2).
1-12
-------
SOLAR MODULE
34 KV DISTRIBUTION LINE
2.5 KV DC BUS LINES
CONTROL & INSTRUMENTATION CABLES
BATTERY BUILDING
L
INVERTER/ ] ' i
REGULATOR ' ''
MODULE
P POWER FACTOR CORR.
T MAI
F FILTER
N
\
SOLAR MODULE
N
\
PATH OF MOTION
\
\
>J
MAINTENANCE ROAD
/
Figure 1 -6. Power conditioning module layout
(Ref. 1-2).
1-13
-------
Figure 1-7. Battery building (Ref. 1-2).
-------
The cells operate at 450 C. The batteries are insulated so that the exterior
surface is 32 C.
Argonne projections suggest that the overall (in-out) battery efficiency
will be 80%. Of the 20% energy loss in a charge-discharge cycle, 8% will
occur during charge and 12% during discharge.
Auxiliary heaters are embedded in the battery banks for reheat in the
event of an idle period exceeding two days. Normally, however, the reject
self-heat will maintain the batteries within their operating temperature range
and no additional power is to be supplied. Should auxiliary heat be required;
however, the resistance heaters will expend about 1 kW/100 kW generating
capacity. Waste heat is removed by circulating air which is discharged at
20 ft above grade. Of the total battery mass, 6% is Li (as metallic Li-At
alloy and as Li-C^). About 1 to 2% is A&. The remainder is KC&, Fe, S, BN,
and structural components. Boron nitride woven fabric is the costliest single
component of a battery, at approximately 0.19 m (20 to 40 g)/kWh and $2150 to
$3225/m . There is some prospect that a nonwoven boron nitride felt can be
developed for which cost projections are about $ll/m . A battery fire would
release caustic Li?O as well as SO_, ASL^Q-zt and various pyrolysis products of
structural components. Non-aqueous fire suppression measures would be
required. However, potential fire hazards due to the high temperature
lithium alloy and other constituents are believed to be minimal since these
materials are contained within an iron cell casing that is further contained
in submodules and insulated containers.
Plant Operation and Operating Modes; A discussion will now be given
of the basic operating modes of the integrated power plant and of the opera-
tional concepts for the solar modules, energy storage batteries, and support
equipment. This discussion is relevant to the environmental analyses be-
cause it relates to the manner in which the plant operations impact utility
grid performance and hence demand for intermediate peaking capacity, uti-
lization of turbines, pumped hydro, and older (inefficient) coal fired plants.
1-15
-------
To assist the reader, the following plant nomenclature is provided.
Collector:
A single parabolic trough
primary supporting a single
Winston secondary containing
a string of photovoltaic cells.
(Inset, Figure 1-3)
Solar Module:
A single sun-tracking, rotating
structure, containing 14 col-
lectors (Figure 1-3).
Group:
An electrically interconnected
set of 100 modules (Figure
1-2).
Array:
The 52 krri assembly of 500
groups (50,000 modules)
Power Conditioning Module:
The pair of buildings compris-
ing battery storage, regulator,
and inverters, etc., servicing
one group of 100 modules
(Figures 1-5 and 1-6).
Unit:
One of the two geographically
separated sections of the plant
(Figure 2-1).
The following discussion is extracted from the Bechtel report (Ref. 1-2)
with slight modification.
For the most part, existing plants in a utility system are operated on
demand and at rated power. Base-loaded plants are kept operating on a
nominal 24-hr-per-day basis. Since the mean number of hours of sunshine
for Las Vegas is 10.5 hr per day (not at full intensity) and storing an addi-
tional 13.5 hr (or more) of energy would be too costly, operation as a base
1-16
-------
loaded plant is not practical. The time of day during which solar energy is
available and the length of time it is available would make operation of the
photovoltaic central station similar to that of an intermediate-type plant.
However, classification into a particular category is much less important
than incorporating the operation of solar power plants into existing and future
generating mixes in a manner that results in the most economical operation
of the entire utility system. With the present conceptual design, the photo-
voltaic central station power plant operates with power output undiminished
by transient cloud cover for as many hours per day as available insolation
and stored energy permit. The stored energy can be derived from solar
energy, off-peak utility, or both.
Typically, daily load curves for a utility show demand to increase
sharply between 8 and 10 a.m. Demand decreases between 6 and 8 p.m. and
then levels off until a sharp decrease at between 10 and 11 p.m. Some util-
ities have a second, smaller peak in the late evening hours. Load demand
curves for weekends have a similar general shape but at a lower power level.
The level of power also varies seasonally. To contribute to the utility sys-
tem's ability to meet such load demands as effectively as practical, it is pro-
jected that the photovoltaic central station be operated in a manner similar to
that indicated by Figure 1-8.
In Figure 1-8, the solid line indicates power available from the solar
array. The dashed line indicates the power being supplied to the utility grid
by the plant. The differences between these two power levels (as indicated by
the shaded areas in Figure 1-8), represent power used to charge the storage
battery or power supplied to the inverter by the battery. The dotted line
represents power supplied by the utility to charge the battery. The battery
charge area indicated is larger than the discharge area due to energy losses
in the battery. The curves shown are highly idealized and are not to scale;
they are intended only to present a general overview of the intended operating
scheme on a typical day. Operation during periods of transient cloud cover,
although not specifically illustrated, will be shown for Mode 4 (see definition
of all operating modes in a later paragraph).
1-17
-------
POWER AVAILABLE FROM ARRAY
POWER SUPPLIED TO UTILITY
POWER SUPPLIED BY UTILITY
/////. BATTERY CHARGING
\\\\\ BATTERY DISCHARGING
TIME OF DAY IHOURS)
24
JL L
I 5
POWER CONDITIONING MODULE MODE OF OPERATION
Figure 1-8. Plant and power conditioning module operation
as a function of time of day (Ref. 1-2).
1-18
-------
Briefly, operation on a typical day is as follows. Off-peak energy from
the utility is used to partially charge the energy storage batteries during the
night. Charging is completed with solar energy during the early morning
hours. As charging is completed and the utility load increases, available
solar power is supplied to the utility grid. Stored energy from the batteries
is used to maintain plant output during periods of cloud cover and as insola-
tion decreases in the late afternoon. Stored energy, as available, is also
used to extend operation of the plant past sunset.
Of course, not all days are typical. On some days, cloud cover will
result in an early draining of the batteries. Also, available solar power and
load demand will vary seasonally. Operation of the plant will involve evalua-
tion of weather forecasts, utility load forecasts and coordination of demand
with expected amounts and times of availability of insolation.
Alternatively, should relatively inexpensive off-peak energy be unavail-
able, the plant would be operated as shown in Figure 1-9- In this case, on a
typical day the plant is operated so that solar energy collected during the
early morning is stored. At midmorning, the plant is connected to the utility
and supplies power at a fixed level for the remainder of the plant's operating
day. Available solar energy in excess of that supplied to the utility is
stored. Stored energy is used to supply power to the utility during periods
of cloud cover and, in the evening, as solar power decreases, to extend plant
operation past sunset. Another alternative is zero energy storage which was
discussed previously.
Many variations and combinations of the above general plant operating
schemes are possible. A major advantage of the first scheme (i.e., Figure
1-8) is that maximum power might be supplied during the time of greatest
load demand. A second benefit is that the fully discharged storage batteries
are initially charged at a high rate, a process that enhances their perform-
ance. Thus, it is proposed as the primary operating scheme and forms the
basis for this current preliminary conceptual design.
1-19
-------
POWER AVAILABLE FROM ARRAY
POWER SUPPLIED TO UTILITY
'////, BATTERY CHARGING
\\\V BATTERY DISCHARGING
TIME OF DAY
(HOURS)
POWER CONDITIONING MODULE MODE OF OPERATION
Figure 1-9. Alternate plant and power conditioning module
operation as a function of time of day (Ref. 1-2).
1-20
-------
Power Conditioning Module Operation; Operation of the plant as de-
scribed is accomplished through the combined operation of the power condi-
tioning modules. There are seven basic modes of operation for each of the
500 power conditioning modules;
1. Group (of 100 modules) supplies power to battery only
2. Group supplies power to battery and inverter simultaneously
3. Group supplies power to inverter only
4. Group and battery both supply power to inverter
5. Battery alone supplies power to inverter
6. Power supplied by the utility to charge battery
7. Shutdown.
The juxtaposition of these modes on a typical day was shown on Figures 1-8
and 1-9. The ensuing discussion of power conditioning modules is prelim-
inary in nature, and the times of day given for initiating operations in the
several modes and power levels are subject to revision. As data on the
array output as a function of time of day become available in actual opera-
tion, a logical step would be to reevaluate the preliminary calculations and
assumptions used to arrive at the operating scheme by modeling the system
on a computer. The model should include factors such as statistical fluctua-
tions in temperature, cloud cover, wind (as it relates to power increases re-
sulting from improved array cooling) and atmospheric conditions in general.
Based on available data, operation of the power conditioning modules on a
typical day can be described as follows:
Mode 1 — Group Supplies Power to Battery Only. In the early morning
hours, between sunrise and 9 a.m.; energy available from insolation is
stored in the battery. The available power varies from zero to about
20 kW per module at 9 a.m. when the utility begins to draw power. During
summer, available solar energy may allow supplying power to the utility
at 8 a.m. Winter conditions may require a shift to a 10 a.m. start.
During these hours, as well as all sunlight hours, the modules revolve
about a vertical axis to track the sun. Conversion of solar energy is
further optimized by operating each power conditioning module to track
the maximum, power point of the combination of the 100 solar modules
connected to its input. This is accomplished by adjusting the regulator
to produce the output voltage that results in having the power supplied
to the battery correspond to the maximum power available.
1-21
-------
When the battery Is fully charged, the program will alert the central
station's control room operators and adjust the regulator to operate
in one of the following modes as preset by the plant operators in the
control room computer.
• Completely stop drawing power from the group (Mode 7)
• Draw available power from the group (up to the maximum
capability of the inverter) and supply it to the utility (Mode 3).
Obviously the latter routine would maximum the use of the plant and
thus obtain the maximum amount of energy per dollar of invested
capital. Bringing power on line is coordinated with the utility system
dispatcher.
Mode 2 — Group Supplies Power to Battery and Inverter Simultaneously.
As in Mode 1, the controller adjusts the firing angle of the regulator to
obtain the maximum power available from the groups and monitors the
state of charge of the battery. A separate control system, which is
part of the inverter electronics, maintains the ac output of the power
conditioning modules at the set value. This is accomplished independ-
ently of the dc voltage at the regulator and battery terminals in the same
manner that tne inverter portions of commercially available uninter-
ruptible power supplies (UPS) maintain a constant power output while
tracking the voltage variation associated with a discharging lead-acid
battery. If the set value of inverter power exceeds the available solar
power, operation in Mode 4 commences.
Mode 2 operation is illustrated in Figure 1-10, which shows the voltage
and currents at the junction of the regulator, battery and inverter term-
inals. As indicated in the figure, the maximum power available from
the module combination, Pm, is a fixed value for this moment in time
and can be delivered at any voltage through the variable ratio trans-
former action of the regulator. Similarly, the nominal set inverter
power, P^, is constant for this moment and can be extracted from the
battery/regulator/invertor junction at any voltage. The power into the
battery, Pb, is a voltage dependent variable. As mentioned, the differ-
ence between the maximum available power from the group and the in-
verter power is used to charge the battery;
P - P. = P, (a)
mi b v '
Or, since only one voitage ran exist at the junction between this equip-
ment:
I - I. = I,
m i b (b)
The inverter draws a fixed amount of power, Pj_. The characteristics
of the solar cells are such that if the battery draws more or less than
the optimum power, Pb, the power from the group will decrease. In
setting the regulator to draw the maximum power from the arrays, the
controller adjusts the regulator output voltage to a single optimum
value, V, such that Eq. (a) is satisfied. The value of this voltage, of
1-22
-------
PB (CHARGE)
M
Figure 1-10. Regulator operational characteristics — ?m > ?i (Ref. 1-2).
course, depends on the stage of charge of the battery. The foregoing
description is somewhat simplified and is intended only to convey the
basic principles of operation. Similarly, Figure 1-10 is not to scale,
and the current-voltage characteristics of the energy storage battery
have been simplified to straight lines. Actual battery characteristics
are a continuum of curves encompassing all states of charge. A more
detailed analysis would also take into account regulator efficiency,
transient response times and control system stability, but such an analy-
sis is beyond the scope of the present conceptual design effort.
As with Mode 1, when the battery approaches full charge, the power
conditioning module controller will alert the control room operators
and adjust the regulator to operate as follows in one of the two sub-
routines of Mode 3;
• Draw only sufficient power from the group to meet the
power set for the module output.
1-23
-------
• Change the set value of power output from the power condi-
tioning modules and supply the maximum available amount
of solar power to the utility grid.
Mode 3 —Group Supplies Power to Inverter Only. A power condition-
ing module operates in this mode when its energy storage battery is
fully charged. Operation in this mode is similar to that of Mode 2,
but the power to the battery P^, is equal to zero, and the inverter
power is equal to the group power (i.e., P. = P ).
Referring to Figure 1-11, the curves for P^ and Pm coincide, and the
optimum operating voltage, V, is set so that the battery neither supplies
nor draws current.
Actually, the controller adjusts the regulator and inverter to operate in
either one or two subroutines in Mode 3 (as described above):
• The regulator and inverter track the group characteristics to
deliver the maximum available solar power to the utility grid
up to the maximum rating of the inverter.
• The regulator is adjusted to deliver only the amount of power
preset for each module; the maximum power point of the
group combination is no longer tracked and operation in this
subroutine is less desirable.
(CHARGE)
(DISCHARGE)
Figure 1-11. Regulator operational characteristics - P = P. (Ref
m
1-24
-------
Mode 4 —Group and Battery Both Supply Power to Inverter. During
times when the maximum power available from the group Pm, is less
than required to meet the power set to be delivered to the utility by the
by the inverter, P:, the stored energy in the battery is used to supply
the difference and maintain the power conditioning module output at its
set value. As illustrated in Figures 1-8 and 1-9, this occurs in the late
afternoon, during hours of waning insolation. Operation in this mode
also occurs during periods of transient cloud cover (not illustrated).
Figure 1-12 illustrates the operation in this mode. In this mode,
Pm < P^, and operation at the maximum group power point requires
that:
P, = P. - P
b i m
PB (CHARGE)
Figure 1-12. Regulator operational characteristics — P < P. (Ref. 1-2),
1-25
-------
As with other modes, control electronics within the inverter maintain
power output at the set value, PI, independently from the dc input volt-
age. The controller adjusts the regulator to draw the maximum avail-
able power from the groups, Pm, and, through the variable ratio
transformer behavior, delivers Pm at the optimum voltage, V. At this
voltage, the discharging battery supplies a current, I]-,, such that ID=Ij.
- Im and Equation (a) is satisfied.
If during operation in Mode 4, the battery becomes discharged to a point
where it, in conjunction with the solar modules, can no longer supply the
rated power to the inverter, the plant control room operator is alerted
and one of two modes is initiated:
• The module is shut down (Mode 7).
• The group alone supplies a lower level of power to the utility
(Mode 3).
Mode 5 — Battery Alone Supplies Inverter. This mode is an extension
of Mode 4, with the group power equal to zero (Pm = 0). Energy stored
in the battery supplies power to the inverter and permits operation of
the plant when severe cloud cover reduces the practical output of the
solar group to zero or past sunset, when stored energy is available.
In this mode, P^ = P^, and the operating voltage is set by the inverter
at whatever level is required to draw the set value of power from the
battery. This is analogous to the operation of an uninterruptible power
supply. When the energy stored in the battery is depleted, as indicated
by a preset cutoff voltage, the power conditioning module is shutdown
(Mode 7).
Mode 6 — Power Supplied by Utility to Charge Battery. The prime
function of the battery is to store energy and deliver this energy when
transient cloud cover would otherwise reduce the plant output. The
battery also enables plant operation to be extended past sunset. Since
the power conditioning modules and battery can function as an energy
storage'load leveling facility, the plant should be operated in this man-
ner when circumstances dictate in order to derive maximum benefit
from invested capital. In particular, when weather forecasts indicate
that insolation on the following day will be greatly reduced, the battery
would be charged with off-peak energy from the utility grid during the
night (midnight to 6 a.m..). To charge the battery, the inverter is
operated as a phase-controlled rectifier. Stored energy (and available
solar energy) is delivered to the grid on the following day in Mode 5
(or 4).
Mode 7 — Shutdown. In this mode, the regulator and inverter are turned
off, and there is no power flow into or out of the power conditioning
modules. A small amout of power is required to keep the controller
electronics ready to act and to maintain the battery at temperature.
Operaton of Solar Modules; With the exception of the rotational track-
ing motion, the modules operate in a static fashion, responding instantly to
1-26
-------
change in any incident solar radiation and requiring no active cooling. In the
evening each module is positioned automatically- to face the easterly rising
sun on the following morning. As the sun's azimuth angle increases during
the day, each module rotates on its support track at the same rate of change
as the sun's azimuthal rate. All control functions for the modules originate
from a central computer located in the plant control building. Expected
maintenance for the modules will consist of absorber assembly change-out,
alignment checks, and tracking system servicing and adjustment.
Battery Operation: As with the solar modules, the operation of the
lithium energy storage batteries is essentially a static process with the ex-
ception of cooling flows. When the batteries are cold prior to plant start-up
the electrolyte is a solid and electrically inert. During the 3.5 day start-up
period, the batteries (for each solar group) are heated with 20 kW of elec-
trical power, normally obtained from solar energy. During operation, the
cells are maintained at 450 C with the exterior (insulated) at 32 C. Air is
recirculated at 375 C with outside air mixed to maintain operating
temperature. During the standby period at night the batteries cool slowly
but do not require heater power to maintain cell temperature within the
operating range.
The batteries are expected to require replacement at approximately 5
to 6 year intervals. Aside from routine replacement and occasional replace-
ment of a failed cell, the battery systems are expected to be essentially
maintenance-free. Minor maintenance of the air cooling system fans and
filters will be required.
The only conceivable environmental impact that the lithium-sulfur
batteries could have is associated with a fire during which fumes could be
released to the atmosphere. As indicated earlier, the lithium material is
well enclosed and insulated and fire hazard is believed to be minimal. Dur-
ing installation or removal of the cells and submodules there will be no pos-
sible spillage since the electrolyte is solid at ambient temperature. However,
since this type of battery has very little service experience, further investi-
gation of the associated fire potential and environmental effects should be made.
1-27
-------
Maintenance Facility and Philosophy
Receiving, maintenance and warehousing will occur in a steel building
located on a concrete pad in the headquarters complex. A 4.8 km rail spur
will be built from the Union Pacific line that runs basically parallel to U. S.
Interstate 15. It will feed into the central warehouse and will be used during
construction primarily, but will also facilitate shipping of replacement and
removed modules, batteries, etc.
Trucks needed for periodic field maintenance and perimeter inspection
will be light duty pickups and/or four-wheel drive vehicles equipped with high
flotation off-road tires. These vehicles will be garaged at the maintenance
facility. Mobile cranes and flat bed trucks capable of transporting entire
modules are available in the Las Vegas urban area.
Lockheed-Hunt sville has considered carefully the various alternative
maintenance and inspection modes and "scenarios." A realistic estimate of
the time required is based on the following: a two-man crew must load a
truck, drive to a module possibly 8 mi distance, disembark, walk around a
module, inspect module wheel bearings visually, shovel a minimum of blown
sand from the track, and continue in like fashion to successive modules.
Periodically the crew would pause to move the truck, record observations,
communicate with a shift foreman, and attend personal needs.
It seems quite unlikely that such a crew could inspect more than 25
modules in an 8-hr shift. Thus, at least ZOOO shifts or almost 16 man-years
would be required for each of 50,000 modules to receive one inspection by a
two-man crew, and practically no maintenance.
It is concluded, therefore, that all maintenance must be by "manage-
ment by exception." Consequently, we anticipate that each module will be
equipped with extensive remotely monitored troubleshooting and perform-
ance test equipment. This would include at least a simple electrical output
monitor, torque or current demand surveillance sensors for drive motors,
temperature sensors on motors and perhaps absorbers, etc. Wheel bearings
1-28
-------
would necessarily include provision for unattended continuous lubrication
with seals to prevent admission of abrasive dust.
The output of each absorber may have to be monitored, at least on a
trial basis in earlier groups. This would assist design upgrading teams in
determining the effect of dust burden and small animal intrusions on re-
flector performance.
As an additional device to minimize field maintenance, several com-
plete modules will be stored at the maintenance shops or at distributed field
sheds. These would be kept as nearly ready-to-go as economically feasible.
When non-trivial maintenance operations become necessary, an entire module
would be removed and replaced. The defective unit would then be trans-
ported to the shops, where its repair could be scheduled locally or at a
factory. A similar approach will be applied to scheduled and unscheduled
battery replacement.
This maintenance management philosophy appears to be consistent with
the small (50 man) operating crew envisioned. By stepwise construction,
bringing each 2 MW group on line as it is completed, operating and mainte-
nance experience can be reflected in occasional design improvements during
construction. Consult the previous discussion of reflective surface deterior-
ation.
This is a very small work force for a 1000 MW generating station.
However, the station is unique in not requiring several distinct types of
personnel. These personnel, include, for example:
• Coal delivery and receiving personnel, including drivers, equip-
ment operators, scales operators, and associated foremen
• Applied health physics personnel (in the case of nuclear plants)
• Fuel test lab personnel
• Ash handling personnel
• Pond management personnel
1-29
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• Cooling tower maintenance crews
• Environmental monitoring technicians (river sampling and analysis,
stack gas samples, etc.)
• Baghouse and precipitator maintenance crews
• Clerical and supervisory personnel related to regulatory agencies;
compliance inspections and reporting, forms management, etc.
Central Headquarters Facility
The headquarters building will house the management office and
central control systems, security, etc. The central control room includes
all panelboards, displays, instrumentation and control elements necessary
for data acquisition, remote monitoring, supervision and control of the plant.
The modular control room panel is provided with a backlighted mimic dis-
play of the power plant power flow from the 500 power conditioning modules
through the plant for power delivery to the utility at Z30 kV. The operative
condition of the system is indicated by conventional signal lights that indi-
cate normal or abnormal conditions.
Routine operation of the plant is by execution of programming stored in
the central control room computer, with operator override to allow for coor-
dination of available (or anticipated) insolation and of stored energy with
utility system load demands. Changes to the program for plant operation or
utility demands are entered by the operator at the operator's console. The
computer in conjunction with the power conditioning module controllers sets
the modes of operation lor the plant. Also, control signals required for
pus tinning (tracking an.- retu-nl of the solar arrays are generated by the
c on puter .
Communications Facilities
Communication systems necessary for plant operation and maintenance
are located in the central control room building. These systems include;
1-30
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• 230 kV power line carrier interface link to the utility system
• VHF transmitter and receiver for plant field mobile units
• UHF transmitter and receiver for utility system tie backup
• Local telephone system line
• Meteorological data receiver
« TV cameras and displays.
A 120 m communication tower is provided in a location (not yet determined)
where it will cause no shadowing of any module. All transmitter/receiver
antennas are mounted on this tower. Aircraft warning light systems are pro-
vided if required by FAA regulations.
Maintenance of plant security is facilitated by the remote controlled
TV cameras mounted at selected perimeter and in-plant locations yet to be
determined.
Transmission Lines
No new transmission lines are required. The 230 kV tower structure
at the plant boundary will connect directly to the existing transmission lines
in the corridor shown in Figure 2-1,
Visitor Center and Visitor Control
This enormous facility —to be the first of its kind and, for a while, the
largest in the United States — is located in the vicinity of Las Vegas, Hoover
Dam, and several national monuments and recreation areas. The facility is
expected to be, for a time, a major tourist attraction.
To facilitate visitor control and to minimize traffic problems asso-
ciated with visitor access, a visitor's center will be established outside the
plant perimeter and adjacent to an interchange on Interstate Highway 15.
Educational displays will include subscale workups, movies, motorized
models, and visitor-interactive exhibits. Bus tours into the plant head-
quarters area can be provided should a demand develop.
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The visitor center and associated service offices will occupy most of
a 744 m , one-story stone structure of indigenous architecture. Building
services will include restrooms and snack services initially for 100 visitors
per day. A parking lot for 50 vehicles and a bus discharge lane are envision-
ed. Provision for expanding the facilities is assumed but not detailed.
Water Supply and Sewerage
This photovoltaic generating plant requires no process water or cooling
water. Potable water and water for sewage treatment and maintenance are
required. There is to be no provision for washing reflective collector sur-
faces. Consequently, the plant will not require an extensive system of water
supply lines.
During construction, crews will be supplied by water truck with 8 m
potable water/day, and sanitation requirements will be met with portable
chemical privies. Substantial amounts of water are needed for production of
0.765 x 10 m of concrete used in foundation preparation. No water pipeline
is planned. Concrete suppliers will operate portable batch plants with
trucked water, or will deliver premixed concrete to the construction site.
•j
Possibly as much as 2850 m /day will be needed on-site if a batch plant
is located there. A source of construction water has not been identified.
Ground water is of low quality, possibly in part because other installa-
tions in the vicinity use deep wells for process waste and sewage injection.
Hence, all potable water will need to be transported to the site even during
normal operation. For this purpose, the headquarters complex and the visi-
tors' center will each require 12 m potable water per day, purified on site
by a small package plant.
During operation, both headquarters complex and the visitors' center
will be served by package sewage plants, with capacities of 12 m3/day.
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Vehicles will not be washed on site. If a need for significant quantities
of water for maintenance should develop, non-potable well water is a possible
solution, but a small pipeline run in along the access road is a more attrac-
tive alternative.
Transportation Facilities
Roads; A permanent access road from Interstate Highway 15 will be
constructed of asphalt at beginning of construction and utilized as the main
access road during construction and operation. This road will be approxi-
mately four miles long and will have an interchange on 1-15.
Design, approvals, funding, etc., will require a substantial period of
time before construction can commence. This should be initiated immedi-
ately upon project go-ahead.
The visitor center, outside the plant perimeter, will have an asphalt
parking lot for 50 vehicles and a bus discharge lane occupying several acres.
Provision for expansion is necessary.
The road leading to the headquarters and maintenance complex will be
a permanent asphalt three-lane access, designed for heavy equipment traffic.
The headquarters parking lot is to accommodate 50 vehicles, and will
also include a bus discharge lane.
Throughout the plant, 6.7 m wide improved (asphalt) maintenance roads
will be spaced every 329.4 m with north-south orientation. No asphalt east-
west roads are planned. However, vehicular access on 15 cm thick crushed
rock spur roadbed will be provided for each module. Hygroscopic dust
suppressant treatment may be nec-essary periodically.
All light duty vehicles assigned to maintenance will require "high-
flotation" off-road tires.
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Railroad: A rail spur line with local side tracks at the warehouse will
be constructed from the Union Pacific line that runs approximately parallel
to 1-15. The spur line will be approximately 5 km long with approximately
90 m of side tracks for railcar positioning.
Helipads: Occasional visitation by dignitaries requiring helitransport
is anticipated. In addition, we expect to use helicopters on a trial basis for
construction supervision, and for maintenance and inspection visits to remote
areas of the plant. Therefore, helipads will be located near the visitor
center, on the headquarters parking area, and at several remote locations
within the plant area.
Plant Security
It is believed that this kind of generating station will be much less vul-
nerable to deliberate acts of massive sabotage or vandalism than a conven-
tional non-modular fossil or nuclear plant. Further, it is expected that the
installation will be accepted with much less public controversy. Therefore,
security arrangement is aimed primarily at prevention of casual ingress,
and theft prevention, public protection, and exclusion of large animals.
The entire plant area is to be secured with a 3 m chain link fence.
Actual ingress at the plant's main entrance will be controlled from a guard
shack. Qnsupervised remote gates will be padlocked.
1.3 PROJECT SCHEDULE
Construction would begin in the western extreme of Unit 1, below Dry
Lake, immediately following preparation of the initial (temporary) haul road
from route U.S. 93. Essentially simultaneously, work would begin on pre-
paring the interchange at 1-15, and on construction of a railroad spur from
the Union Pacific line. The spur would connect with the main line at a point
in Section 21, R.64E., T.17S near the settlement of Dry Lake where the main
line lies west of 1-15. Thus no new overpasses over U.S. 93 or 1-15 would
1-34
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be required. The cloverleaf interchange on L-15 and the temporary haul road
from U.S. 93 would be the only interference with these two highways.
Early stages of construction activity are expected to employ 200 work-
ers rather quickly, exclusive of employment in railroad and haul road con-
struction. As land preparation is succeeded by foundation work and module
installation, the work force will reach about 1000, and will continue near that
level for several years. Meanwhile, land preparation crews move on to the
next projected area. Construction is scheduled to be complete in ten years.
An advantage of the split site (units one and two being on opposite sides
of Dry Lake) is that Unit 1 can be completed and be on-line, almost wholly
undisturbed by continuing construction in Unit 2. A detailed logistical analy-
sis has not been done to determine if the overall construction time would be
shortened appreciably by opting for an integrated plant located in its entirety
north of Dry Lake.
1.4 PROJECT COST
The total projected capital cost of this hypothetical 1000 MW solar energy
plant has been estimated based on the current design, year 1990 solar cell cost
projections, and other cost data from Refs. 1-1 and 1-2. The total capital cost
of the plant is projected to be $1670 million, or $1670 per kilowatt (peak) (Table
1-1), exclusive of land costs.
Two major uncertainties in this estimate are:
1. A major cost element with a large uncertainty is the solar photo-
voltaic cells. Estimates of present day costs are $20 to $40 per
watt. Table 1-1 assumes a projected cost of $1.00 per peak watt.
2. A breakdown of major plant cost elements appear in Table 1-1.
Note that the cost of the solar modules, less the absorber units
is the major cost item and one for which the cost will probably
be reduced through mass production techniques. In particular,
superstructures produced by techniques used in automotive and
airframe industries are possible alternatives to the current de-
sign. The latter presumes welded construction using current
industry standard tubing and pipe, for example.
1-35
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TABLE 1-1. PLANT COST ELEMENTS
Item $M
Solar modules, including foundations
and construction cost 800
*
Solar cell absorber units (14 per module) 200
Power wiring and controls 40
Power conditioning modules (including
projected cost of batteries) 350
. **
Labor at site 20
Contingency at 15% 220
Total $1670
*
Based on $1.00 per peak watt for silicon colar cells, $10.00 per sq ft
for reflector optics and structure.
**
Labor other than for solar module construction.
Considering the possibility of reductions in the cost of superstructures,
solar cells, and absorber optical components, it may be possible to reduce
the plant cost to the vicinity of $1400 per peak kilowatt (1976 dollars). This
exceeds the projected cost of the proposed 3GWe Kaiparowits coal fired plant,
$1167 per peak kilowatt electric, when that project was cancelled in April 1976
(Ref. 1-4).
Because of diurnal variations in insolation, temperature cycling, etc.,
the ratio of peak output to average output will be approximately 5:1. There-
fore, the theoretical maximum annual energy supplied by the plant (capacity
factor 1.0) would be 1.75 x 106 MWh. This assumes unlimited storage. The
3 hours storage capability supplied for the plant limits the capacity factor to
0.50 in conventional terms. Actual capacity factors which might be experi-
enced are unknown. Anticipated improvements in silicon absorber efficiency
by the time final modules are installed will be offset to an unknown degree by
degraded performance of older modules. Therefore, we take as an approxi-
mation a capacity factor of 0.5. This corresponds to an annual production of
0.876 x 10 MWh.
1-36
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We use an 18% figure for annualized amortization, money cost, taxes
and insurance, and 1.8% annual operating expenses. This is rather low, but
possibly consistent with the small work force. The corresponding cost of
delivered electricity is $0.377 per kilowatt-hour based on a level rate struc-
ture. This, of course, ignores land acquisition costs if any, and very pos-
sibly other hidden costs.
By way of comparison, retail residential power in the U.S. "sunbelt"
from Tampa to Los Angeles and as far north as Salt Lake City ran $0.022 to
$0.044 per kwh in the winter of 1975-76. One southeastern utility company
paid $0.10 per kilowatt-hour during that winter for wholesale peak power off
the grid. Even including a projected twenty-fold reduction in solar cell costs,
cost of photovoltaic power from this station would exceed traditional power
costs throughout the U.S. by a factor of 4 to 17. Because the incremental
effect of a single plant on a large utility's overall delivered power costs
would be small, stations similar in characteristics, cost and environmental
effects may be built. Should other advanced energy options fail to assume
importance (cf. Section V), or if fossil fuel costs inflate much faster than is
happening now, demonstration plants of this type may become attractive be-
cause their capital costs are predictable and their labor costs small.
Many public utilities in the U.S. Southwest currently have very high
fractions of natural gas in their fuel mix. These utilities necessarily will
be seeking alternative energy sources as natural gas supplies become ex-
hausted in the foreseeable future. We have not performed an analysis to
determine if this generating station (hypothetically) would be going on-line
with a timing permitting its substitution for gas-fired boilers. Such an
analysis would have to relate the presumed timing of utilities' growing con-
fidence in the viability of solar photovoltaic generation with the time of
utilities' decision-making in the long lead-time preceding nuclear or fossil
fuel plant construction. Such an analysis could be valuable to Federal and
State energy and environmental administrators, but is outside the scope of
the present task.
1-37
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1.5 PERMITS AND REGULATIONS
Permits
No navigable waterways are used, crossed, discharged into, or
withdrawn from. Consequently no U.S. Army Corps of Engineers nor
U.S. Coast Guard jurisdiction exists. The installation has no tall stacks;
no Federal Aviation Administration permit is required. The absence of
liquid discharges means no USEPA-NPDES wastewater discharge permit
is required. The Federal Energy Administration does not issue permits.
It has authority to issue prohibition orders; we do not expect that to occur.
The Nuclear Regulatory Commission is without jurisdiction. The number
of areas in which regulatory jurisdiction is avoided is a unique character-
istic of a power plant of this type.
The following permits are required:
Nevada —Certificate of Public Convenience and Necessity
Nevada —Authority to operate two package secondary
sewage treatment plants
Nevada —Permit to construct, operate, and maintain
overhead transmission lines
Nevada —Permit to drill well (if needed)
Clark County District Health Department — Permits
relative to air pollution regulations.
In addition, there are potentially numbers of local permits and certifi-
cates relative to building codes, zoning, water supply, personnel certifi-
cations, business licenses, taxes, etc., which are beyond the scope of
this task to discuss.
Clark County Regulations
Ambient Air Quality and Pollutant Emissions: Clark County, Nevada,
air pollution regulations are contained in the District Board of Health of
Clark County, Nevada, Air Pollution Control Regulations of January 28,
1973, and proposed amendments, dated March 27, 1974. The Nevada
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Revised Statutes transfer authority to enforce and regulate state regulations
from the State Environmental Protection Commission to the Clark County
District Board of Health, Air Pollution Control Board. The Clark County
Air Pollution Control Board is also authorized to adopt, amend, or modify
rules and regulations, providing the action is consistent with, or provides
more stringent control than, state regulations.
Some Federal, Nevada State, and Clark County ambient air quality
standards and pollutant emission limitations are shown in Table 1-2.
Clark County standards and limitations are equal to or more stringent than
state and Federal criteria with the exception of oxides of nitrogen emis-
sions where only Federal standards presently exist for steam generating
plants, Clark County particulate matter regulations concerning opacity
are more stringent than the Federal regulations restricting particulate
emis sions.
The proposed complex source regulation amendment to the air
pollution regulations probably will not apply to this installation.
Registration and Permits (Air Quality and Fugitive Dust) for
Source Emissions: Any person who causes, lets, permits, suffers, or
allows the emission of air contaminants, whether or not limits are esta-
blished, shall file with the Control Officer on forms provided by the
Control Officer.
The applicant is required to provide information on refuse disposal,
fuel used, and specific nature and quantity of the air contaminants emitted
together with location of source and stack data. A separate application is
required for each new source. The definition of a source of air contami-
nant is anything that emits any air contaminant The Registration Certifi-
cate issued by the Control Officer is not an acceptance or approval of any
article, machine, equipment, process or other contrivance listed on the
Registration Certificate. The Registration Certificate is renewable
annually on or before February 24 of each year.
1-39
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TABLE 1-2. SELECTED AIR QUALITY STANDARDS
Federal Standards
Primary Secondary
Air Pollutant Averaging Standards Standards
Time /Zg/m3 /Ug/m3
V
o
Particulate AGM*
matter
24 h
(not to
exceed
once/yr)
Ozone 1 h
(not to
exceed
once/yr)
#
Annual geometric mean
**' ^* f, ^i
75
260
160**
60
150
160"
Nevada State
Averaging
Time
AGM
24 h
(maximum)
1 h
(maximum)
Standa rds
Limits
i"g/m3
60
150
. **
160
Clark County
Averaging
Time
AGM
24 h
(maximum)
1 h
(maximum)
Standards
Limits
60
150
. **
160
0.08 ppm.
-------
No person is allowed to operate any item requiring a Registration
Certificate unless an operating permit for such operation has been issued
by the Control Officer and such permit is current and valid. The Control
Officer may issue an Operating Permit on a conditional basis for a new
source that requires some reasonable time for initial testing. Operating
Permits are subject to revocation.
An Emergency Episode Plan will be prepared and submitted to the
Control Officer defining a standby plan for reducing or eliminating emis-
sions of air pollutants during periods of an air pollution alert, air
pollution warning, or air pollution emergency as defined in Section 6 of
the State of Nevada Air Quality Implementation Plan, which is entitled,
"Emergency Episode Plan." In general, construction contractors for this
project will be capable of appropriate operational cutback during emergency
episodes. The episodes shall be identified when any of the specified pollutants
exceeds the levels shown in Table 1-3 and meteorological conditions are such
that pollution concentration can be expected to remain at levels above those
shown in the table for 12 hours or more.
Fugitive Dust: The Clark County air pollution regulations require
that no person shall cause or permit the handling or transporting or
storage of any material in a manner that allows or may allow controllable
particulate matter to become airborne. A further requirement states all
activities associated with construction and operation of this plan will re-
quire all reasonable precautions to abate nuisance caused by dust and to
prevent its (dust) transmission beyond the boundary line of the real prop-
erty on which it originates.
The fugitive dust section of the Clark County Air Quality Regulations
requires a current and valid permit issued by the Control Officer before
any lessee, owner, occupant, operator, user, or any other person may
disturb the topsoil of any property within Clark County, Nevada. The per-
mit is subject to the applicants agreements: to implement an acceptable
1-41
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TABLE 1-3. POLLUTION CONCENTRATION CONDITIONS*
Pollutant/Meteorological .
Condition Alert Warning Emergency
Particulate, 24-hr avg.
(jLtg/m3) 375 625 875
Particulate coefficient
of haze (COH) 3 57
Particulate x SO 24-hr
avg. (COH x ftg/m3) 524 2,096 3,144
(|Lig/m3 x jUg/m3) 65 x 103 261 x 1Q3 393 x 103
Ozone, 1-hr avg. (jug/m3) 200 800 1,200
*
Excludes entries not relevant to proposed action,,
method to prevent particulate matter from becoming airborne; to imple-
ment an acceptable method of securing the topsoil when the project is
finished; to take additional precautions as may be reasonably prescribed
by the Control Officer (consistent with the regulations); and to suspend all
or part of his activities if he cannot provide satisfactory control of air-
borne particles, or upon notification by the Control Officer or his repre-
sentative.
Nevada Air Quality regulations require a fugitive dust registration
certificate or operating permit for the purpose of clearing, excavating, or
leveling land of 8.1 hectares or more for any building construction. An
operating permit for the deposit of any foreign material covering land of
8.1 hectares acres or more is also required.
In accordance with the Nevada Revised Statutes, the State of Nevada
has authorized the Clark County Air Pollution Control Board to regulate
and enforce State and County Air Quality and Fugitive Dust regulations.
Furthermore, the Control Officer (Clark County) is required to make avail-
able to the applicant the necessary procedures and application forms.
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Noise; Property development standards of Clark County Nevada
Zoning Code contain noise restrictions. Clark County, Nevada, Code
29.44.50, Subsection K, specifies the octave band levels of noise which
shall not be exceeded at each boundary line of the property on which sound
is generated. The exceptions to the noise code allow temporary noise that
is due to construction activities. The proposed activity will be in complete
compliance.
Land Use: The Clark County Regional Planning Council is a coordi-
nating group between the Clark County Department of Planning, State
Department of Conservation and Natural Resources, and Federal agencies
such as the Bureau of Land Management. The Council published a Clark
County Park and Open Space Plan in 1971 with recent updates indicating
resource inventory and potential areas of similar development, including
priority recommendations,
State of Nevada
Air Quality: State of Nevada air pollution regulations are contained
in the State of Nevada Air Quality Regulations, Sections 1 through 12, as
amended February 24,1974, effective March 27, 1974. Enforcement
authority is contained in the Nevada Revised Statutes. Nevada has also
prepared and submitted its Air Quality Implementation Plan to the Environ-
mental Protection Agency, accompanied by a letter from the State Attorney
General's office stating that the required legal authority exists for the
State of Nevada as promulgated in the Federal Register, dated August 1971,
to execute its implementation plan for Federal air quality standards in con-
formity with Clean Air Amendments Act of 1970. The State of Nevada
ambient air quality standards were shown in Table 1 -2.
Fugitive Dust: State of Nevada Fugitive Dust regulations are con-
tained in the Nevada Air Quality Regulations. The Clark County and State
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of Nevada requirements are essentially identical with minor differences
in which Clark County is more stringent and specific.
Registration and Permits (Air Quality and Fugitive Dust): A sepa-
rate operating permit is required for each new or existing source. Ope-
rating permits shall expire and will be subject to renewal five years after
the date of issuance.
Possession of a valid Registration Certificate will be a prerequisite
to obtaining the initial operating permit for a new source. Registration
Certificates are valid for a 1-year period and require renewal.
Water Quality: Water Pollution Control Regulations for the waters
of the State of Nevada were adopted by the State Environmental Commis-
sion on October 24, 1973. Existing standards for the State include the
revisions adopted April 10, 1973, June 26, 1973, and those of October 24,
1973.
There does not appear to be any activity associated with this solar
power plant which would diminish the quality or use class of any natural
waters.
Permits and Registration for Waste Discharge: A permit is required
from the State of Nevada Bureau of Environmental Health before any
person or entity may construct, install, expand, or significantly modify
any factory, mill, plant, or other industrial or commercial facility that
will result in a waste discharge, not authorized by an existing permit,
to waters of the State. This includes facilities used for treatment and/or
discharge. The proposed activity will not fall under these provisions
according to present plans.
Solid Waste: Although the solar power plant will produce no fuel or
process wastes, there will be construction debris and dunnage, which
will cause Nevada to have regulatory jurisdiction.
1-44
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State of Nevada solid waste regulations are included in State of
Nevada Regulations Governing Solid Waste Management, adopted January
17, 1973, by the State Board of Health. Authority for regulations and
enforcement is contained in th^. Nevada Revised Statutes. The Regulations
further state that nothing contained therein shall be construed to abridge the
authority of a town, city, or county to establih by ordinance or otherwise,
higher standards than those contained in the State regulations.
General standards for solid waste systems require that all solid
wastes shall be stored, collected, utilized, treated, processed, and dis-
posed of in a manner such that a health hazard, public nuisance, or
impairment of the environment will not be created. All solid waste
systems shall be operated in such a manner so as not to cause or contri-
bute to pollution of the atmosphere, surface, or groundwaters. Solid
wastes will not be placed in surface or groundwater or within 4 feet of the
highest groundwater table (the health authority may require a greater
separation in special cases). No solid wastes handling, processing,
salvage, or disposal will be placed in operation unless approved by the
health authority.
Solid waste storage, collection, and transportation are to be im-
plemented in such a manner as not to allow the contents to blow, spill,
leak or fall. Where spillage does occur, the area is to be properly cleaned
and solid wastes returned promptly to the vehicle or container.
Site location will conform to land use planning and not be within
402 m of the nearest inhabited dwelling or place of public gathering or be
within 305 m of a public highway unless special provisions for site beauti-
fication, litter control, and vector control are included in the design and
meet with the approval of the health authority.
Design of the disposal site requires provision for prevention of
scattering of papers and other light-weight debris, control of vehicular
and livestock access, and control of surface and runoff waters to prevent
pooling on top and minimize percolation through filled or working areas.
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Operation and maintenance will be in such a manner so as not to create
odors, unsightliness, or other nuisances. A minimum, compacted uni-
form depth of cover material of 61 cm shall be placed on any surface that
represents the final grade. Final cover will be graded to drain surface
runoff water with a top slope of Z to 4%. Suitable grasses shall be planted
as required in completed areas of the landfill to prevent erosion, surface
deterioration, and fugitive dust. Adequate water shall be available at all
times for dust control and for compaction of cover material. Access to
the land disposal site shall be controlled as to the time of use and as to
those authorized to use the site. An attendant shall be on duty to control
access during hours of operation,
The Nevada State Health Authority must approve all plans for design,
operation, and maintenance of solid waste disposal systems. Application
requires a report and design plan. The plan shall be prepared by a
properly qualified engineer and shall include a general location map show-
in;; land use and zoning within 40Z m of the disposal site; and topographic
map(s) of the area, which should be at a scale of not more than 1:2400
with contour intervals not exceeding 1.5 m, showing proposed fill
areas, borrow areas, access roads, typical cross section of a lift, grades
for proper draining of each lift, special drainage, gas control devices if
required, fencing, equipment shelter, employee facilities, and all other
pertinent data to indicate clearly that the land fill will be developed,
operated, and completed in an orderly manner. The report should define
who is to be served; anticipated types, quantities, and sources of solid
wastes to be disposed of; site geology, hydrology, and soil conditions;
source type and quantity of cover material; area, water resources, includ-
ing groundwater elevation and direction of movement; operating procedures;
required personnel; and equipment.
Federal Regulations
Air Quality: The U.S. Environmental Protection Agency (EPA)
has approved the Air Quality Implementation Plan of the State of Nevada
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except where it fails to meet significant deterioration of ambient air
requirements.
Fugitive Dust: Federal fugitive dust standards are principally re-
lated to occupational health. The Occupational Safety and Health Act of
1970 (OSHA) provides the authority for the United States Department of
Labor, Occupational Safety and Health Administration, Occupational Safety,
and Health Standards, The fugitive dust standards are presented in
Table 1-4.
Permits and Registration for Emissions: The EPA requires a plant
review prior to construction The Administrator is also to be notified 30
days prior to the initial operation with confirmation of action within 1 5
days after startup. Compliance testing as established by EPA is generally
less stringent than for the State of Nevada and Clark County. The
numerical values for selected EPA air standards were presented in
Table 1-2.
Water Quality: Water quality standards contained in Water Pollution
Control Regulations for the waters of the State of Nevada have been pre-
liminary approved with proposed amendments by EPA. There does not
appear to be any Federal water quality jurisdiction for this proposed plant.
Solid Waste: Federal regulations for solid waste disposal are con-
tained in Environmental Protection Agency 40CFR241, Guidelines for the
Land Disposal of Solid Wastes. The authority for the regulations is pro-
vided in Section 209 of the Solid Waste Disposal Act, PL89-272, as
amended by PL91-512. The Federal solid waste will be disposed of on
Federal lands. The guidelines are also mandatory for Federal agencies.
Construction debris and dunnage will be disposed of according to pertinent
requirements of 40CFR241, which states that only waste for which the
facility has been specifically designed shall be accepted. Generator-
owner of excluded waters (hazardous) and the responsible regulatory agency
shall jointly determine a method for disposal of excluded wastes.
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TABLE 1-4. OSHA STANDARDS FOR FUGITIVE DUST
Concentration
Substance mg/m3 10 particles/m
Coal dust (respirable fraction
less than 5% SiO2) 2.4 —
Coal dust (respirable fraction / 10 \
more than 5% SiC>2)* \%SiO2 + 2/ —
Inert or nuisance dust
(respirable fraction) 5 530
Inert or nuisance dust
(total dust) 15 1767
Crystalline quartz / 10 \ / 8834 \
(respirable) \%SiO + 2) \%SiO H- 5 /
Crystalline quartz
(total dust)
/ 30 \
\%SiO + 2 )
*
Intent of law is to regulate free silica (crystalline portion; i.e., quartz)
The hydrogeology of the site shall be evaluated in order to design
the site development in a manner to protect or minimize the impact on
groundwater resources.
Environmental factors, climatological conditions, and socioeconomic
factors shall be given full consideration as selection criteria.
The location, design, construction, and operation of the land dis-
posal site shall conform to the most stringent of applicable water standards
as established in accordance with or effective under the provision of the
Federal Water Pollution Control Act, as amended. In the absence of such
standards, the land disposal site shall be located, designed,constructed,
and operated in such a manner as to provide adequate protection to ground
and surface waters used as drinking water supplies.
1-48
-------
The design, construction, and operation of the land disposal site
shall conform to applicable ambient air quality standards and source con-
trol regulations established under the authority of the Clean Air Act as
amended or state and local standards effective under that act, if the latter
are more stringent.
Conditions shall be maintained, which are unfavorable for the
harboring, feeding, and breeding of vectors.
The land disposal site shall be designed and operated at all times
in an esthetically acceptable manner.
In order to conserve land disposal site capacity, thereby preserving
land resource, and to minimize moisture infiltration and settlement,
municipal solid waste and cover material shall be compacted to the small-
est practical volume.
The land disposal site shall be designed, constructed, and operated
in such a manner as to protect the health and safety of personnel associated
with the operation. Pertinent provisions of the Occupational Safety and
Health Act of 1970 (PL91-596) and regulations promulgated thereunder
shall apply.
The owner/opnrator of the land disposal site shall maintain records
and monitoring data to be provided as required by the responsible agency.
Permits and Registration for Solid Waste: In addition to the fore-
going general criteria, 40CFR241 requires that a solid waste disposal
system description address the following in content and format:
a. Types and quantities of all wastes
b. Site development plans prepared or approved by a professional
engineer
c. Initial and final topographies at intervals of 1.5 m or less
1-49
-------
d. Land use and zoning within 402 m of the site including
location of all residents, buildings, wells, water courses,
arroyos, rock outcroppings, roads, and soil and rock
borings
e. Location of all utilities within 153 m of the site
f. Employee convenience and equipment maintenance facilities
g. Narrative description, with associated drawings indicating
site development and operation procedures
h. Description of the project use of the completed land disposal
site
i. Current and projected use of water resources in the potential
zone of influence
j. Groundwater elevation and movement, and proposed separation
between the lowest point of the lowest cell and the predicted
maximum water table elevation
k. Potential interrelationship of the land disposal site, local
aquifers, and surface waters based on historical records
or other sources
1. Background and initial quality of water resources in the
potential zone of influence
m. Proposed location of observation wells, sampling stations,
and testing programs planned, where appropriate
n. Description of soil and other geologic material to a depth
adequate to allow evaluation of the water quality protection
provided by the soil and other geologic material
o. Provision for surface water runoff control to minimize
infiltration and erosion of cover material
p0 Potential of leachate generation and proposed control
systems where necessary to protect ground and surface
waters
q. If the site is located in a flood plain, it shall be protected
against at least the 50-year design flood by impervious
dikes and other appropriate means.
As stated earlier rainwater runoff from any material storage pile must be
collected and treated to limit the concentration of pollutants to: TSS, not to
exceed 50 mg/^ and pH within the range 6.0 to 9.0.
Land Use; Federal standards require that the lands managed by the
Bureau of Land Management for which an applicant requests development
1-50
-------
be specifically designated as other than resource land inventory. This
requirement is implied and specific in the National Environment Policy
Act, and the guidelines for Federal agencies promulgated under the act.
Noise: The United States Department of Labor has developed guide-
lines under the authority provided in OSHA. The standards applicable to
the construction and operation of this project allow such high noise levels
as to be irrelevant to the project.
1.6 REFERENCES
1-1. Davidson, Joseph K., and H. Lundgren,, Letter report to Spectrolab,
Inc., on a "Conceptual Design of a Photovoltaic Central Station Power
Plant (Module)," Ingenasu Associates, Tempe, Arizona, May 1976.
1 -2. Bechtel Corporation. A Preliminary Report on a Conceptual Design
of a Central Station Power Plant. Prepared for Spectrolab, Inc.,
under Subcontract No. 66725, San Francisco, California, January 19760
1-3. Chilenskas, Albert A., Argonne National Laboratory, Argonne, Illinois.
Private communication with D. Richard Sears of Lockheed-Huntsville,
June 1976.
1 -4. Anon: Kaiparowits Power Project Dropped. Coal Age, May 1976,
p. 25.
1-51
-------
SECTION 2
ENVIRONMENTAL SETTING WITHOUT THE PROJECT
Note; The assigned scope of this task specifically demands reduced
emphasis on background information, historical trends and socioeconomic
analyses. Therefore, this section represents about the very minimum ma-
terial that an interested reader would need in order to proceed independently
with even the most perfunctory analysis. The corresponding portions of
Sections 3,4, and 6 through 11 will be even briefer.
2.1 LOCATION
Units 1 and 2 comprise, respectively, 25.1 and 54.88 km tracts, lo-
cated on either side of Dry Lake, about 32 km northeast of Las Vegas,
Nevada. Figure 1-1 places the facility with respect to major political and
geographical features of the U.S. Southwest. Figure 2-1 presents an over-
lay of the plant boundaries upon the U.S. Geological Survey map NJ11-12
(1969) "Las Vegas." Depicted in the figure are not only units 1 and 2, de-
scribed in Section 1, but also the perimeter of a possible alternative site.
(The latter is referred to in Section 2.9 "Ecological Setting." In Sections 1
and 5, some implications of a split site are identified. It is beyond the scope
of this task to analyze the relative advantages and tradeoffs in detail since
very much less baseline data are immediately available.)
Unit 1 would occupy all or part of sections 22, 23, 24, 25, 26, 27, 34, 35,
and 36 of T. 17S, R63E; sections 1, 2, 3, 10, 11, 12 and 13 of T.18S, R63E; and
sections 6 and 7, T.18S, R64E. Elevations are 610 to 720 m above MSL.
2-1
-------
Figure 2-1. Relationship of the plant site to topographic features.
2-2
-------
Unit 2 is proposed to occupy all or part of sections 24, 25, 26, 35, and
36 of T.16S. R.63E; sections 19-36 of T.16S, R.64E; and 8, 9, 10, 11, 15, 16 and
17 of T.17S, R.64E. Elevations are 610 to 720 m above MSL.
The alternative site is continuous with unit 2, includes all of it, and in
addition extends northward and eastward to include all or part of sections
1-13 (except 6) of T.16S, R.64E; 4, 5,6, 7, 8, 17, 18, 19, 20, and 30 of T.16S,
R. 65E0 Elevations are 610 to 781 above MSL, (excluding hills to 854 m in
sections 2, 3, 10 and 11 of T.16S, R.64E).
Located between these two units is Dry Lake, an alkali flat de-
pression which is not suitable for construction because it floods to depths of
several meters every few years. Standing water disappears in a few months.
2.2 REGIONAL DEMOGRAPHIC, SOCIOECONOMIC, AND COMMUNITY
CHARAC TERISTICS
(The material which follows is largely from the Harry Allen Station
Environmental Assessment, Ref. 2-1. Very detailed and extensive base-
line data are contained in that assessment, which may be regarded as
supplementary to this section.)
Historic Population and Population Projections
The major population center in the study area is the city of Las Vegas,
which in 1974 had an estimated population of 146,900 or 42% of the population
of Clark County, which had 349,000 persons (Table 2-1). The city of Las
Vegas has been a major population growth center since World War II. Since
1940, when 8432 persons were counted, the population of Las Vegas has
grown exponentially. North Las Vegas, a functional part of the metropolis,
has had similar growth.
Henderson, in Las Vegas Valley, and communities in the Moapa
Valley have experienced fluctuating and declining population. The locations of
these communities are not shown in Figure 2-1. They are just NE of the NE
corner of that map.
2-3
-------
*
TABLE 2-1. HISTORICAL POPULATION
Location , p.p.
Las Vegas Valley
Las Vegas 8,432
North Las Vegas —
Henderson —
Moapa Valley
Glendale —
Logandale —
Moapa —
Overton —
Total Clark County 16,414
State of Nevada 110,247
1960
64,405
18,422
12,525
—
809
432
1,162
127,016
285,278
1970
125,787
36,216
16,395
—
426
353
1,336
273,288
488,738
July 1,
1973
135,355
41,400
17,650
70
395
41
1,292
331,700
559,316
July 1,
1974
146,900
45,000
16,500
(**)
(**)
(#*)
(**)
349,000
583,563
Sources: Clark County Regional Planning Council, Nevada Bureau
of Business, and Economic Research.
**
No estimate made.
Several population projections for Clark County have been developed.
They cover a very wide spectrum of future population levels due to differ-
ences in assumptions, forecast techniques, and sophistication. A number of
the population projections for Clark County are presented in Figure 2-2.
Employment Characteristics and Labor Force Inventory
As analyzed by the Nevada Employment Security Department, the geo-
graphical labor market area consists of Clark County and Beatty Town-
ship of Nye county. Together, these areas comprise the Las Vegas Standard
Metropolitan Statistical Area (SMSA). Beatty Township is in: luded in the
normal Las Vegas SMSA because it contains most of the Nevada Test Site and
the Nuclear Rocket Development Station where historical employment peaks
2-4
-------
to
Ln
eoo.ooo -
700,000 -
600,000 -
500,000 -
400,000 -
300,000 -
200,000
Clark County Regional Planning Council
Univtnify of Nivada, Bur«ou or Bu»ln«»i and Economic
Buraou of Economic Analyst! . 06CRS - Strlat E
Projected
830,000
1970
1975
1980
1985
1990
1995
2000
Figure 2-2. Projected population — Clark County, Nevada.
-------
have reached 10,000 persons. These two nuclear-related facilities had a
combined employment of 5,300 persons in March 1975.
Since I960 the service industries (personal, business and hotels,
gaming, and recreation) have engaged the largest percentage of the total
civilian labor force (TCLF). Manufacturing has not provided much employ-
ment, and in March 1975 employed only 3.1% of the TCLF. Likewise, the
agricultural and mining sectors employ a very small percentage of the TCLF.
Currently, the fourth largest segment of the civilian labor force is un-
employed. The 18,000 persons out of work, but still in the labor force,
represent 11.3% of the TCLF. Details are presented in Table 2-2. In Table
2-3, a breakdown is given of construction-related crafts union membership,
indicative of the labor force available for plant construction. Table 2-4 pre-
sents employment projections, presumed to include all major anticipated
construction projects, including power plants.
Family Income
Family income levels for both the State of Nevada and Clark County are
well above national figures. The major source of family income is wage and
salary income with 63,609 families in Clark County averaging $11,219 of in-
come. Self-employment generated an average income of $8,632 for 5,564
families. The per capita money income for the State of Nevada was $3,554
in 1970 and $3,538 for Clark County. The national average was $3,119.
The average annualized wage of all classes of construction and opera-
ting personnel employed at this hypothetical plant would exceed the Clark
County average very substantially.
Community Infrastructure
In 1974, Clark County contained four cities, nine towns, one school dis-
trict, four special school districts, and 12 nonschool special districts. Cities
provide urban facilities and services such as streets, public safety, sewage,
and refuse disposal, among others. Special districts in Clark County provide
2-6
-------
TABLE 2-2. LABOR FORCE, BY INDUSTRIAL SECTOR
(LAS VEGAS SMSA - I960, 1970, 1975)*
Occupation Group
Personnel (thousands)
1960
*u,
-i-
1970
March 1975
Services
Trade
Construction
Man uf a ctu rin g
Transportation and
Public Utilities
Finance, Insurance
20.9
8.4
3,7
2.6
3,8
51.1
21.2
7.2
4.2
7.2
68.3
26,8
9.2
4.9
8.7
and Real Estate
Government
Mining
Agriculture
Other
Unemployed
Total Employment
Total Civilian
Labor Force
1.4
6.2
0.4
0.5
5.8
3.0
53.7
56.7
4.1
16.3
0.1
0.4
9.7
7.1
121.5
128.6
5.7
19.5
0,2
0.7
- -
18.0
139.5t +
157.5
Source: Manpower Report. Nevada Employment Security
Department. 1975.
**A 1
Annual average.
Established-Based Industrial Employment. Reflects employ-
ment by place of work. Does not necessarily coincide with
Labor Force concept. Includes multiple jobholders.
Adjusted by census relationship to reflect number of persons
by place of residence.
2-7
-------
TABLE 2-3. UNION MEMBERSHIP
Craft Membership
Asbestos workers 160
Boilermakers 400
Bricklayers 160
Carpenters 800
Cement masons 320
Electricians 960
Ironworkers 320
Laborers 1600
Linemen 160
Millwrights 400
Operating engineers 800
Painters 480
Pipefitters 800
Sheet metal workers 560
Teamsters 1200
Total 9120
TABLE 2-4. EMPLOYMENT PROJECTIONS, LAS VEGAS
SMSA (1980-2000)
Source 1980 1990 2000
Department of Commerce,
Bureau of Economic
Analysis (1972)
(OBERS Series E)
Nevada Employment
Security Department
Clark County
Regional Planning
Council (1972)
157,000
216,000
H 204,000
M193,000
L 186,000
186,000
333,000
266,000
248,000
214,100
377,000
333,000
311,000
2-8
-------
services such as fire protection, water, sanitation, and libraries. School
districts also function independently to administer public education at the
local level. Detailed descriptions of the housing availability, vacancies, etc.,
are contained in Ref. 2-1.
Education
Schools in Clark County are slightly underutilized (Table 2-5) and
an influx of construction workers might be expected to impact school enroll-
ment. However, projected growth patterns overwhelm the small contribu-
tion due to the small work force anticipated for this project (Table 2-6).
The University of Nevada at Las Vegas (UNLV) is the second largest
education system in Nevada with an estimated 18,725 students and 621 pro-
fessors in fall 1974. It is anticipated that a law school will open on the
campus in the fall of 1976.
Clark County Community College was founded in 1971 with an appro-
priation from, the State Legislature of $442,000. In 1973, there were 850
students in career development programs. The college anticipates a $2
million campus and a student body of 3,000 in its three-part master plan.
Very few construction craftsmen would be expected to request evening
continuing education service from these two schools. Engineering personnel,
perhaps even during construction, however, might request professional
courses.
Hospital Facilities
Health services in Clark County are provided by a system of nine hos-
pitals with a total of 1,579 beds. The ratio is approximately five beds per
1,000 population. Most of the facilities provide for out-patient as well as
24-hour emergency services. In addition to the nine hospitals, the area has
several childrens1 clinics and numerous convalescent homes.
2-9
-------
TABLE 2-5. SCHOOL CAPACITY AND ENROLLMENT,
CLARK COUNTY SCHOOL DISTRICT (1973-1974)*
Attendance
Area
Las Vegas
Henderson
Boulder City
Moapa Valley
Virgin Valley
Indian Springs
Rural
Total County
^ -.L **
Capacity
70,123
4,955
1,532
1,051
400
493
148
78,702
Enrollment
69,491
4,686
1,662
756
345
359
118
77,377
Difference
632
269
(90)
295
55
134
30
1,325
*Source: Clark County School District, 1973, "Master Plan."
&
Capacities based on utilization factors of: (1) 100% at the
K-6 grade level and special education; (2) 90% at the 7-8,
7-9 and 9-12 grade levels; and (3) 85% at the 10-12 grade
level.
TABLE 2-6. PROJECTED SCHOOL BUILDING NEEDS,
BY ATTENDANCE AREA, CLARK COUNTY
SCHOOL DISTRICT*
Attendance Area Projected Building Needs
Las Vegas 5 elementary schools, 2 junior high schools,
1 high school
Henderson 14 elementary classrooms
Boulder City 10 elementary classrooms, 8 junior/senior
high classrooms
Moapa Valley 2 classrooms
Virgin Valley 2 classrooms
Indian Springs 2 classrooms
Rural No additional facilities required
*
Source: Clark County School District, 1973, "Master Plan."
2-10
-------
Transportation
Transportation facilities for passenger and freight in Clark County in-
clude air facilities, a highway system, interstate bus transit, surface transit
and railroad freight. The railroad currently serves Las Vegas with freight
stops (12 to 15 daily) for freight movement and crew changes.
Two modes of transportation which have expanded throughout the years
are air and highway transportation. McCarren International Airport at Las
Vegas, was completed in 1974. It provides passenger and cargo service
through scheduled airlines (Air West, Delta, Frontier, National, TWA, United
and Western), third level carriers, supplemental carriers including charter
flights, and general aviation.
There are six major highways in Clark County; Interstate Highway 15
north to Salt Lake City, U.S. Highway 95 north to Tonopah-Reno, U.S. High-
way 95 south to Searchlight, U.S. Highway 93 south to Kingman, Interstate
Highway 15 south to Los Angeles, and U.S. Highway 93 north to Idaho. Traffic
counts for 1973 show Interstate Highway 15 south having an average daily
traffic volume of 10,850 vehicles, while Interstate Highway 15 north, near
the proposed site, handled 5,550 vehicles daily.
Three interstate bus lines serve Las Vegas: Greyhound and Sun Valley,
Continental, and Las Vegas-Tonopah-Reno Stage. The total passenger volume
for 1971 was nearly 1.5 million passengers. The privately owned and oper-
ated Las Vegas Transit System provides service to major portions of the Las
Vegas Valley, primarily for tourists.
The 1973 annual report of the transportation study reflected the impor-
tance of land use analysis as a factor in planning and forecasting future urban
requirements; namely, increases in population, business and industrial
growth, schools, and parks, while reducing uneconomical sprawl or isolated
pockets of development in future traffic patterns.
2-11
-------
Electrical Energy
Nevada Power Company, which serves Clark and Nye counties, experi-
enced a 4.3% increase in electric energy sales in 1974. Electric energy
usage statistics for 1972-74 are given in Table 2-7.
*
TABLE 2-7. ELECTRIC ENERGY USAGE
Item
Sales (1000 kWh)
Residential
Commercial and Industrial
Other
Total
Customer Accounts
1974
1,814
2,132
295
4,242
113
,638
,143
,770
,551
,021
% of
change
+ 1
+7
+ 1
+4
+4
.2
.5
.8
.3
.6
1973
1,792,
1,983,
290,
4,066,
108,
688
701
422
811
088
% of
chang
+ 12.
+ 9.
+ 17.
+ 11.
+ 8.
e
8
1
1
2
1
1972
1,589,
1,819,
248,
3,656,
99,
667
023
117
807
996
Source: Greater Las Vegas Chamber of Commerce. 1975.
Other
Reference 2-1 contains detailed discussions and data concerning:
• Public Safety
• Utilities
• Natural Gas
• Public Finance and Taxation
• Power Company Appraisals and Tax Liabilities
• Pending Tax Legislation
• Tourist/Convention Industry
• Service Industries
• Agriculture and Mining
and other topics related to secondary socioeconomic impacts of plant con-
struction.
2-12
-------
2.3 WATER RESOURCES, USE AND QUALITY
The material in this section is extracted from the much more detailed
report in Ref. 2-1.
Supply and Use
Natural springs in the Las Vegas Valley and flow from artesian wells
had to be augmented by pumping in 1941 to keep pace with increased water
consumption due to increased urbanization. Residential and transient use of
water accounts for 62% of water withdrawals in the Las Vegas Valley.
For 1973, 86.3 x 10 m were withdrawn from groundwater, 92.4 x 10
•2 63
m were withdrawn from the Colorado River, and 11.7 x 10 m were re-
cycled from, wastewater. Trends in water use from 1969 to 1973 show a de-
crease in groundwater extraction, slight increases in wastewater reuse, and
significant increases in diversions of Colorado River water (cf. Table 2-8).
Projections of water consumption in the year 2000 show a doubling of water
demand if the projected 700,000 population is attained.
Colorado River water represents the major water source for the Las
Vegas Valley. The 1964 U.S. Supreme Court ruling in the case of the State
of Arizona versus the State of California established the amount of Colorado
River water allocated to the State of Nevada. This ruling provided for a
1.31 x 10 m /yr allotment to Nevada if sufficient mainstream water is
available for release.
Not all of this total entitlement is available to the Las Vegas Valley
due to other commitments. Table 2-0 lists the projected distribution of
Nevada's allotment of Colorado River water. In order to meet the area's
growing water needs as well as to relieve excessive dependence on ground-
water, the Colorado River Commission of Nevada undertook the southern
Nevada Water Project, designed to provide 1.31 x 10 m of Colorado River
water for domestic and industrial use. The first phase of the project was com-
9 3
pleted in 1971 and the total of 5.76x 10 m of water was distributed through
various agencies, as shown in Table 2-10.
2-13
-------
TABLE 2-8. WATER USES AND SUPPLY DISTRIBUTIONS -
LAS VEGAS VALLEY (1973)*
Parameters
History for Year 1973
With Estimated July 1, 1973
Population of 316,725 People
9 3
acre feet 10 m
Water Used
Potable Water —
Residential and Transient
Parks and Public Facilities
Golf Courses
Agriculture
Heavy Industry
Commercial and Light
Industry
Military
Total Potable Water Used
Reclaimed Wastewater —
90,000
9,200
6,100
3,000
13,600
20,000
3,200
145,100
3.92
0.40
0.27
0.13
0.59
0.87
0.14
Parks and Public Facilities
Golf Courses
Agriculture
Power
Total Reclaimed Waste-
water Used
Total Water Used
Water Supplied
Groundwater Withdrawals
Colorado River Diversions
Reclaimed Wastewater
Total Water Supplied
0
1,200
4,500
3,700
9,400
154,500
70,100
75,000
9,400
154,500
0
0.05
0.20
0.16
0.41
6.73
3.05
3.27
0.41
~6T7T
Source: Nevada Environmental Consultants. 1974
2-14
-------
TABLE 2-9. PROJECTED DISTRIBUTION OF NEVADA'S ALLOTMENT
OF COLORADO RIVER WATER""
Allotment, acre feet/yr'
Year
1970
1980
1990
2000
2010
2020
Water
Available
300,000
300,000
300,000
300,000
300,000
300,000
Fort Mohave
Steamplant
Nil
30,000
25,000
15,000
Nil
Nil
Fort Mohave
Land Develop.
Nil
8,000
13,000
13,000
13,000
13,000
Federal
1,000
2,000
4,000
6,000
6,000
6,000
For use in
Metro L. V.
Sub -Area**
299,000
260,000
258,000
266,000
281,000
281,000
Source: Nevada State Engineer (1971) as reported in Nevada Environmental
Consultants. 1974. Facilities Plan Pollution Abatement Project
Las Vegas Wash and Bay, Annex A.
A«
"l acre-foot = 43560 m3.
Does not include credit for return flow.
Includes water delivered through facilities of Southern Nevada Water
Project, Boulder City, and BMI.
TABLE 2-10.
PHASE I SOUTHERN NEVADA WATER SYSTEM
DELIVERY COMMITMENTS*
Agency
Las Vegas Valley Water District
City of North Las Vegas
City of Henderson
Nellis Air Force Base
Boulder City
Total
109 m3/Yr
4.32
0.87
0.30
0.17
0.09
Percent of
Total
75
15
5
3
2
Too"
Source: Nevada Environmental Consultants, 1974.
2-15
-------
Based upon the construction of Phase II facilities and the availability of
Colorado River water, options for additional deliveries through the Southern
Nevada Water System were extended to those agencies listed in Table 2-11.
TABLE 2-11. PHASE II; SOUTHERN NEVADA WATER SYSTEM
DELIVERY OPTIONS*
Agency
Las Vegas Valley Water District
City of North Las Vegas
City of Henderson
Boulder City
Total
Q "3
1 f\ s /
10 m /yr
4.36
0.87
1.44
0.57
7.27
Percent of
Total
60
12
20
8
100
'I'
Source: Nevada Environmental Consultants, 1974
9 3
The State of Nevada annual entitlement of 13.07 x 10 m may be ex-
ceeded in any given year by the amount of water returned to the Colorado
River System.
Treatment and reclamation of wastewater provides a third significant
water resource. Statistics for 1973 revealed that wastewater reuse in Las
Vegas Valley approximated 11.7 x 10 m of a total 64.7 x 10 m avail-
able for reclamation and reuse. The amount of wastewater available
for reuse is expected to increase proportionately with future population
growth within the Las Vegas Valley.
The 1974 report by Nevada Environmental Consultants (NECON) en-
titled Facilities Plan Pollution Abatement Project Las Vegas Wash and Bay.
Annex A, provides a comprehensive description of water resource uses and
needs within the Las Vegas Valley. This report has been adopted by the
Clark County Board of Commissioners and has been utilized for source data
for this discussion of present and projected water needs within the Las Vegas
Valley.
2-16
-------
Projections of water needs and supply distributions for the year 2000
are given in Table 2-12. NECON (Nevada Environmental Consultants) used
the Clark County Regional Planning Commission population projections for
both medium and high growth within the Las Vegas Valley. Assuming a popu-
lation level of 700,000, water needs will more than double by the y:,ar 2000.
Groundwater withdrawals will continue to decrease, but there will be signifi-
cant increases in Colorado River diversions and reclaimed wastewater u.3e
when the proposed Advanced Wastewater Treatment Plant becomes available.
Surface Water
Except at times of unusual rainfall, no material surface water exists in
the vicinity of Units 1 and 2. The occasional flooding of Dry Lake and its
ecological consequences is discussed in Section 2.9.
Groundwater
A geohydrologic investigation of Dry Lake Valley was made in 1972 to
determine the suitability of the playa as a disposal site for wastewater from
the Las Vegas area. No field investigation of groundwater conditions was
made for the present study. Groundwater quality fails to meet U. S. Public
Health Service Standards with respect to at least one component for each test
well analyzed (Ref. 2-1). See Table 2-13.
Dry Lake Valley Basin; The Paleozoic carbonate rocks and the alluvial
deposits of Dry Lake Valley are relatively permeable and will yield water to
wells where saturated. The Muddy Creek Formation and the Playa silts and
clays in the central portion of the basin are nearly impermeable, and act as
aquicludes. Lithology of these units is discussed in detail in Ref. 2-1.
Only three water wells within the Dry Lake Valley are known to pene-
trate the limestone rocks. Construction data for these wells is unknown and
it is not known if production is from the limestone or overlying sediments.
However, it is believed that at least a portion of the water yielded to these
wells comes from the limestone rocks. The carbonate rocks which comprise
2-17
-------
TABLE 2-12.
WATER NEEDS AND SUPPLY DISTRIBUTIONS -
LAS VEGAS (2000)*
Projections for Year 2000
For Medium
Population of
700,000
Parameters
Water Needs
Potable Water Needs
Residential and Transient
Parks and Public Facilities
Golf Courses
Agriculture
Heavy Industry
Commercial and Light Indus.
Military
Total
Reclaimed Wastewater Needs
Park and Public Facilities
Golf Courses
Agriculture
Power
Heavy Industry
Total
Total Water Needed
Water Supplies
Groundwater Withdrawals
Colorado River Diversions
Reclaimed Wastewater"*"
Total Water to be
Supplied
**
acre
feet
212,800
10,000
6,000
3,000
32,200
46,900
7,700
318,600
11,000
9,800
8,500
39,500
-0-
68,800
387,400
50,000
268,600
68,800
387,400
i • i i • *i^ ^*
billion
gallons
69.34
3.26
1.96
0.98
10.49
15.28
2.50
103781
3.58
3.20
2.77
12.87
-0-
22.42
126.23
16.29
87.52
22.42
For Maximum
Population of
805,000
acre5'~'1<
feet
244,700
13,200
6,100
4,000
32,600
53,900
8,900
363,400
11,000
11,800
8,500
39,500
4,400
75,200
438,600
50,000
313,400
75,200
438,600
billion**
gallons
79.74
4.30
1.98
1.31
10.62
17.56
2.90
3.58
3.85
2.77
12.87
1.43
24.50
142.91
16.29
102.12
24.50
142.91
Source: Nevada Environmental Consultants, 1974.
'l acre-foot = 43560 m ; 109 gallons = 3.785 x 106 m3.
Contingent upon completion of Advanced Wastewater Treatment Plant.
2-18
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TABLE 2-13. GROUNDWATER QUALITY, DRY LAKE VALLEY,
CLARK COUNTY, NEVADA*
Standard
Mineral
Constituents,
Heavy
Mineral
Constituents,
Ca
Mg
K
Na
K + Na
co3
HCO3
Ci
so4
NO3
F
B
Alkalinity
as CaCO3
Fe
TDS
Si02
Turbidity (J.U.)
pH
Color
11-131
0-84
16-93
129-516
9-154
0-600
0-278
120-378
19-700
0-71
1.4 - 4.3
0.09 - 0.65
28-878
0.01-20
350-3000
23-25
0-97
7.5-11.5
0-15
As
Ba
Cd
Cr
Cu
Pb
Mn
Hg
Se
Ag
Zn
Tr -
0.04
0.003
0.007
0.014
0.037
0.05
0.001
0.002
0.008
0.089
0.078
-0.075
- 0.016
- 0.024
- 0.034
- 0.112
- 0.0017
- 0.0096
- 0.028
- 1.86
Data are extrema of data for all test wells reported in Ref. 2-1.
2-19
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the major portion of the surrounding hills are present to unknown depths be-
neath the basin, and extend beyond into adjacent basins. Permeability of these
rocks is considered moderate to high due to open fractures and joints. Solu-
tion cavities and openings have been observed in surface outcrops; southern
Nevada is known to have cavernous limestones. The balance of wells in the
valley extract water from the alluvial deposits that surround the Lnterfinger
with Muddy Creek and playa deposits.
Permeability of the alluvium is probably greatest in the southern por-
tion of the valley where the materials are derived almost entirely from
erosion of the limestone, and little is derived from the Muddy Creek forma-
tion .
Groundwater Occurrence and Levels: Within Dry Lake Valley, data on
groundwater are available from only nine water wells, of which only two are
active. Additional data are provided by two observation wells. Three of the
water wells penetrate Permian sandstone and/or limestone basement rocks
as reported by driller's logs. Groundwater extractions from the two active
wells is'estimated to be about 2.18 x 10 m /yr.
Groundwater levels and elevations within Dry Lake indicate the gradient
is nearly flat and suggest minor amounts of groundwater flow.
Within the study area, the amount of groundwater recharge is small.
Only the southern and western alluvial fans within Dry Lake Valley are suffi-
ciently permeable to accept large quantities of water by percolation. Waters
that infiltrate the alluvium outside the extent of the playa clay may reach the
regional groundwater system. Where infiltrating water encounters the playa
and Muddy Creek clays, it may form local perched groundwater systems. It
is estimated 35 x 10 m of water is recharged to Dry Lake Valley annually.
This figure includes both alluvial and carbonate rock areas.
In a closed basin, such as Dry Lake Valley, recharge to the ground-
water will cause water levels to rise until there is discharge by subsurface
outflow, or by surface discharge to the floor of the playa. The groundwater
2-20
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surface has not been raised sufficiently to reach the playa surface. Sub-
surface outflow may be occurring when water levels attain an elevation
above 556 m.
Interbasin movement of groundwater through the carbonate rocks is
considered possible. For Dry Lake Valley, the extremely flat gradients
and general lack of data preclude any definitive determination of the direction
or quantity of such movement. Studies by the U. S. Geological Survey have
shown interbasin movement of groundwater to be occurring in basins of
southern Nevada.
Water Quality and Use; Ranges of water quality analyses of samples
taken from wells in Dry Lake Valley are shown in Table 2-13. All but one
of the samples are from, the alluvial aquifer; the exception is apparently from
the carbonate aquifer. These data indicate the quality of the groundwater in
the Dry Lake Valley is generally poor for drinking purposes. The United
States Public Health Service Drinking Water Standards (1963) of permissible
levels of constituents are exceeded for at least one of the several constituents
in each well. These include nitrate, cadmium, lead, manganese, fluoride,
iron, and total dissolved solids. Salinity ranges from about 350 to 1730 ppm
and averages about 1100 ppm.
The mineral constituents of the waters vary from sodium sulfate, to
calcium sulfate-chloride, to calcium sulfate. This probably reflects leach-
ing of gypsum and base exchange of clay minerals in the playa alluvium and
Muddy Creek Formation.
2.4 SANITATION AND WASTE MANAGEMENT
This material is quoted from Ref.2-1.
Wa st ewat er Tr eatment
Wastewater in Clark County Ls managed by the city of Henderson, city
of Las Vegas, city of North Las Vegas, Clark County Sanitation District, and
Basic Management, Inc. Most of the facilities are reported to require reno-
vations to enhance treatment capabilities and expansions to accommodate
2-21
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continued urban growth. The treatment plant in Henderson is reportedly-
obsolete and its expansion is not economically feasible.
The cities of Las Vegas and North Las Vegas operate a joint treatment
plant with the design capacity of 1.14 x 10 m /d. An average flow of 8.74 x
10 m /d was recorded in 1973. The present plant location is able to accom-
modate additional facilities including tertiary treatment installations.
The Clark County Sanitation District is under the control of the County
Board of Commissioners. The District's service area covers over 414 km
of unincorporated urban fringe areas. Current average daily flow at the
county sewage treatment plant is 8.3 x 10 m /d. At the present rate of growth
demands on the District's facilities are expected to reach the average design
capacity in about 5.5 years. The annual per capita cost of sewer service in
Clark County was $10.40 in 1972.
Solid Waste
Solid waste disposal in the cities of Las Vegas, North Las Vegas,
Henderson, and Boulder City is managed by mandatory subscription to a
private contractor. Voluntary subscription service is available to residents
of other small communities. Approximately 85% of Clark County residents
receive solid waste collection service.
Sunrise Mountain Sanitary Landfill, located about 13 km northeast of
McCarran International Airport, is the largest of 24 disposal sites in Clark
County. In 1973, over 259,000 MT of solid waste were disposed of at the
site, representing 96% of all solid wastes generated in Clark County.
Las Vegas Valley residents generate about 1.6 kg of solid waste per
capita per day while commercial establishments generate about 1.1 kg per
capita per day. Tourist activities in hotel-casinos generate approximately
0.34 kg of solid waste per capita per day.
2-22
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Solid waste generation cost factors for 1973 were estimated at $12.54/
MT residential service and $25.42/MT for commercial service. Pro-
jected annual total solid waste quantities based upon projected trends in unit
rates of solid waste generation and Clark County Regional Planning Council
medium-growth population projections are 454,000 MT in 1980; 680,000 MT
in 1990; and 907,000 MT in 2000.
2.5 LAND USE
This facility will require the hypothetical dedication of about 52 km
for a prolonged, perhaps indefinite, period. The projected life of the plant
is 30 years, preceded by phased construction over 10 years, resulting in a
minimum commitment of 40 years. Careful appraisal of current and future
land use practices near the site and in the vicinity is required.
The two units, illustrated in Figure 2-1, are separated by the Dry Lake
depression shown on current topographic maps. Historically the area accu-
mulates alkali water from rain run-off every two to three years, and has
reached depths of 1.2 to 1.5 m. This flooding precludes siting of either solar
modules or ancillary electrical equipment and structures on the lake.
Land uses throughout the study area are relatively scarce. Transmis-
sion lines and transportation corridors are predominant in the valleys. There
are few industrial mining land uses, or dwellings near the study area.
Many of the remaining land uses near the proposed sites are designated
parks, natural areas, or recreation resources, and are generally located in
the mountainous areas.
Rural Residential: Approximately seven structures are located adjacent
to the Dry Lake between the original U.S. Highways 91 and 93 road alignment
and Interstate Highway 15. Only two of these are still inhabited. One mobile
home trailer is situated south of Dry Lake adjacent to U.S. Highway 93.
2-23
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Transportation and Utility Corridors: Numerous transportation and
utility corridors are presently located within the study area.
A. Highways
1. Interstate Highway 15 passes in a southwest to northwest direction
through the Dry Lake Valley. The 1973 daily traffic volume for
this portion of Interstate Highway 15 was 5025.
2. U.S. Highway 93 is a paved state primary highway that is routed
north-to-south through Hidden Valley between Las Vegas and Arrow
Canyon Ranges. Traffic volume in 1973 averaged 550 vehicles per
day.
3. Nevada State Highway 40, a secondary highway connecting Interstate
Highway 15 with Nevada State Highway 12, provides access into
Valley of Fire State Park. This highway crosses through the north-
ern part of the study area. Daily traffic volumes averaged 100 in
1973.
B. Railroads
The Union Pacific Railroad is routed in a generally south-north
direction, through Dry Lake Valley, passing adjacent and west
of the Dry Lake Range. An auxiliary railroad spur that connects
an industrial plant to the main railroad is routed east of the Las
Vegas Dunes Recreation Area, located in the southern part of the
study area.
C. Transmission Lines
1. The study area is crossed by four transmission lines. Two
parallel, 230 kV, wood-pole lines that originate at the Reid
Gardner Station north of the study area, pass southwest through
Dry Lake Valley and connect to a substation located in the
northern part of Las Vegas Valley.
-2. The Navajo-McCullough 500 kV lattice tower line parallels the
230 kV lines north of the Dry Lake Valley. The line diverges
north of the Dry Lake Range, crossing Interstate Highway 15 and
passing east of the Dry Lake Mountain Range in a southerly di-
rection through the valley and portions of the Muddy Mountains.
3. An H-frame, wood-poled, 69 kV line parallels U.S. Highway 93
through Hidden Valley. This line, following a southern route
through mountainous topography, connects to a small substation
and continues into the Las Vegas Valley.
2-24
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Heavy Industry: The Apex Mining and Processing Plant is a lime
mining and processing facility, located on the west side of Interstate Highway
15 south of Dry Lake Valley. It is a large-scale, heavy industrial land user,
encompassing 162 hectares.
Agriculture: Agricultural activities produce a minimal input to the
Clark County economy. Agricultural employment was about 700 persons in
March 1975. The utilization of migrant workers to supplement local labor
supply tends to cause employment fluctuations during harvest periods. The
Moapa Valley (64 km northeast of the plant site) constitutes the primary
agricultural area within Clark County. This narrow, 16 km long valley
bordering the Muddy River produces sugar beet seeds, tomatoes, radishes
and green onions. The dairy industry of Clark County is also located in the
Moapa Valley. In 1969, the last year for which data are available, there were
only 159 agricultural operations (1.9% of land area) of all types in Clark
County. The productivity of the region is so low that the farm value (1969
dollars) was only $6 10/hectare, including both land and buildings.
At the plant site there is no agricultural activity of any sort. The hard
pan (caliche) is reported to be only 25 to 46 cm below the surface. Further,
there is a 5 to 8 cm deep vesicular layer at the soil surface which reduces
downward heat penetration and dissipation. Consequently, the plant area has
no potential agricultural productivity whatsoever, even with irrigation, now
or in the foreseeable future (Ref.2-2).
Mining: The mineral industry in Clark County has experienced pro-
nounced fluctuations due both to external demands and mineral discoveries.
Discoveries of gold and magnesium have caused periodic increases in mining
activities since 1906.
The annual value of total mineral production in the State of Nevada and
Clark County was $120.4 x 10 and $12.3 x 10 , respectively.
Gypsum is the major mined mineral resource in Clark County. Major
gypsum mining activities are carried out by the U.S. Lime Products division
2-25
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and the Blue Diamond division of the Flintkote Company, the Texas American
Sulphur Company and the Pabco Gypsum division of Fibreboard Corporation.
As of March 1975, mining operations employed 200 persons in Clark County.
Lithium deposits have been reported in some areas of southern Nevada
(Ref. 2-3). Whether or not recoverable reserves exist at the plant site is not
known to us. However, U.S. reserves are amply large for current uses. The
plant site area is not likely to be exploited until some time after proposed
facility decommissioning. Should lithium battery and fusion power require-
ments for lithium both develop, the resource situation would be unclear, and
is currently being debated (Ref. 2-4).
Active mining claims exist in the vicinity, including one with Unit 1.
See Section 3.2. BLM has not validated the claim yet, and does not have in-
formation on the minerals claimed.
Recreational Use; We are aware of only one significant recreational
use of the plant site. (The conditions are severe and uncomfortable.) Re-
creational off-road vehicle use is occurring and the proposed site is a BLM
approved location for large off-road competitions. This use is being dis-
couraged and controlled elsewhere on Federal lands. See Section 3.2.
There may be use by amateur collectors of archaeological and histor-
ical artifacts. This activity constitutes an irreversible and uncontrolled ex-
ploitation which is being prohibited or discouraged elsewhere.
Conclusions: Outside of urban areas, Clark County has low productivity
in land-related activity. The plant sites, Units 1 and 2, in particular, appear
to be waste lands, wholly without current or potential agricultural use and
little confirmed mineral value.
The alternate site has not been studied with respect to land use aspects.
2-26
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2.6 GEOLOGY AND HYDROLOGY
Nearly all material in this section has been extracted from the Harry
Allen report (ReL 2-1) in which very much more detailed discussion appears.
Geology
Investigations; The Dry Lake Valley has been investigated several
times over the past few years to determine the feasibility of the area for
waste disposal, groundwater extraction, and for the Interstate Highway 15
freeway. Many logs of exploration holes were obtained. A program to in-
vestigate the Dry Lake Valley for recent faulting and subsidence, and for pre-
liminary foundation conditions for a plant site and water retention ponds was
conducted during April through July 1975.
Regional Geology: The proposed plant is located in the central portion
of the Basin and Range Physiographic Province. The dominant geologic fea-
ture of this province is north-south trending fault block mountains with inter-
montane alluvial filled valleys. Within the Basin and Range Province, large
scale folding, thrust faulting, and strike-slip faulting are present. Rock
formations include sedimentary, igneous, and metamorphic rocks ranging in
age from Precambrian to Recent.
Internal drainage characterizes much of the northern and central por-
tions of the Basin and Range Province becoming less pronounced in the
southern section, although southern Nevada is known to contain cavernous
carbonate rock.
The stratified rocks in the vicinity of Dry Lake Valley are largely
Ordovician through Permian limestone and dolomite, which rest unconform-
ably on Precambrian basement rocks. The geologic features of southern
Nevada suggest that the area has been subjected to several periods of tectonism
throughout geologic history.
Local Geology
The geologic features exposed in the vicinity of the Dry Lake Valley are
typical of those generally present throughout the Basin and Range Provence.
2-27
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The formations exposed In the local mountain ranges have been subjected
to extensive folding and faulting. The intermontane basins in the vicinity of
Dry Lake Valley are structural basins that have been downfaulted. This is
reflected by large thicknesses of sediments that fill these basins with alluvial
and lacustrine materials consisting of gravels, sands, silts, clays, and evap-
orites of the Pliocene Muddy Creek Formation. Locally, Quaternary playa
deposits occur in the central portions of these basins. The Muddy Creek
Formation, present throughout most of the study area unconformably over-
lies the Paleozoic carbonates. It is poorly to moderately indurated and
varies in color from buff, to brown, to red.
A large fault scarp, offsetting the alluvial fans up to 34 m, was in-
vestigated about 40 km northwest of Dry Lake in the Sheep Range. This
fault was assumed not to be more than a few hundred years old.
After being downdropped, Dry Lake Valley began receiving sediment
from the surrounding higher areas with the coarse gravel materials being
deposited at the mouths of the drainages and the fine materials being de-
posited outward into the basin. Being a closed bain, it also received runoff
and apparently contained a large saline lake through Pliocene times (The
Muddy Creek formation). Sediments are present in the basin to elevations
over 610 m. They consist of poorly indurated siltstone, claystone, and fine-
grained sandstone. These materials are often gypsiferous and contain layers
of crystalline gypsum and halite.
Data indicate that subsidence of the basin occurred prior to deposition
of the playa sediments, and of the more recent alluvial fan sediments. The
alluvial fan deposits were examined carefully in every wash, gully, cut, and
exposure from the mountains to the playa for evidence of cracking, discon-
tinuities, and offset. No cracks, offsets, discontinuities, or other evidence
of faulting or subsidence was found within these recent sediments.
2-28
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Geology of Recommended Site
The proposed site (Units 1 and 2) is located on the alluvial fans at the
south end of Dry Lake Valley just up-slope from the north and south ends of
the Dry Lake Playa (Figure 2-1). The Arrow Canyon Range borders the site
on the west and south. The site has a central area, not planned for use,com-
prised of the Dry Lake Playa. The Dry Lake Range lies about 3.2 km to the
east of the site area.
The southern portion of Dry Lake Valley is mantled by thick coalescing
alluvial fans that slope from the mountain toward the Dry Lake Playa. Drill
hole data, widely spaced, show the fan materials to interfinger not only with
the playa materials but also with the Muddy Creek sediments as well.
Materials underlying the site are composed of coarse gravel from sand
to boulder size fragments with some silt and clay to a depth of about 30 m
The gravels are principally subrounded to subangular limestone fragments.
They are well compacted, weakly cemented, and are permeable. A well
cemented caliche layer generally occurs over the area from 1.5 to 3 m below
the surface, but is reported to be 25 to 45 cm below the present surface in
some portions of the site area (Ref. 2-2). Its thickness is variable, but was
found to be up to 1.8 m in some exposures.
The water table was found to occur at about elevation 556 m above
MSL, which corresponds to the approximate highest elevation of the clay
surface below the deep gravels.
The periphery of the playa is bordered by alluvial fans composed of
silty gravel that interfinger with the playa silt and clay. Some gravel
lenses protrude considerable distances into the playa materials.
Voids or cracks were encountered in several of the drill holes.
Several holes in previous investigations accepted the pump capacities of
thick drilling mud with little or no back pressure. The voids are believed
to have formed as the result of subsidence and partial solution of the
evaporites.
2-29
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A minimum number of in-situ permeability tests were performed in
the playa, Muddy Creek, and the alluvial fan deposits. The tests were per-
formed in accordance with Designation E-18 and E-19 of the U.S. Bureau of
Reclamation, Earth Manual. These test results, combined with the drilling
fluid loss indicating the presence of voids in some holes, show that materials
are sufficiently permeable to allow significant seepage.
Seismology
General: A study was made of the literature pertaining to the seis-
micity in the vicinity of the Harry Allen Station site. Historical records in-
dicate the areas of earthquake activity and levels of associated damage for
this region of the United States; the seismic history is used in determining
the design earthquake intensity for this site.
A number of linear features that could be interpreted as faults are
present in the Dry Lake Valley. Many of these were investigated both by
inspection and trenching. No evidence could be found to indicate offset has
occurred since deposition of the most recent alluvial fans. It is concluded
that although faulting and extensive subsidence has occurred throughout the
site area in the geological past, none has occurred since deposition of the
Quaternary gravel and playa deposits.
Earthquake History
Historical records indicate that several significant (intensity V and
greater) earthquakes have occurred within 80 km of the site area; however,
all but one have centered in the vicinity of Lake Mead and these have occur-
red since filling of the lake began in 1935 (Figure 2-3).
More than 10,000 earthquakes have occurred at Hoover Dam since it
was built. A study of the records of these earthquakes makes it clear that
they were related to the increasing weight of the water, since no earthquakes
were reported by the few local inhabitants in the 15-yr period prior to the
dam's construction.
2-30
-------
\
NJ
I
U)
Figare 2-3. Recorded seismic events in Southern Nevada and adjacent portions
of California, Utah, and Arizona (Ref. 2-1).
-------
Earthquakes in the vicinity of Lake Mead have also been described.
The seismicity associated with Lake Mead has been cited by some workers
as a classic example of earthquakes caused by reservoir loading. The epi-
centers of these earthquakes are distributed around Lake Mead.
• Extensive geologic study of the Lake Mead area was carried out
prior to the construction of the dam, and the entire region was
found to be broken up by countless minor faults. None was con-
sidered to be active prior to the construction of the dam, however,
and the subsequent seismic activity is believed to have been caused
by reactivation of some of these pre-existing faults.
• . . .After several smaller dams were built above Hoover Dam in 1962
to regulate the flow of water, the water level ceased fluctuating as
much as it had in previous years and there was a 50% decrease in the
number of earthquakes.
Only three significant (intensity V or greater) shocks are listed in Earthquake
History as being centered in this area since 1962. The largest shocks occur-
ring in the vicinity of Lake Mead were of intensity VI. The plant site area
lies in an area that has experienced intensities of V, but is close to the in-
tensity VI zone.
Based on the available information it seems that the site area has ex-
perienced relatively low intensities from earthquakes during historical
times, and should expect intensities no greater than VII at the site in the
future. Therefore, from standard engineering practices a value of 0.15 g
will be used for design.
Foundation Considerations
The upper alluvial material has adequate density and strength to sup-
port heavy plant structures on relatively shallow spread foundations. Settle-
ments resulting from application of heavy loads will be small.
Water soluble minerals are found approximately 30 m below the sur-
face in the plant area. The frequency of rainfall and associated runoff is not
great enough to cause percolation of the waters to this depth. As a result,
leaching of these soluble minerals from the formation would not occur.
2-32
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If massive and repeated flooding occurred due to construction-
associated hydrologic modifications, percolation to the soluble minerals
could result. The scarcity of rainfall together with the nature of the grading
and construction activity preclude such a result.
Grading and Excavations: The alluvial material in general can be
excavated with conventional equipment, even though the material is weakly
cemented. Layers of hard caliche are present in the upper several feet of
the alluvium stratum. Muddy Creek Formation is not expected to be en-
countered at the foundation levels of the proposed structures,
Fill Materials: The required quantities of materials for structural
fill and backfill purposes can be obtained from onsite sources.
Laboratory Testing: A laboratory test program consisting of: soil
type identification, moisture content and dry density, specific gravity,
particle size analysis,Atterberg limits, shear strength parameters, con-
stant head permeability tests, and consolidation tests on undisturbed and
remolded samples was performed for the Harry Allen plant assessment.
Chemical tests were performed to evaluate sulfates, chlorides, and soluble
salts present in the subsoil materials. Results appear in Ref. 2-1.
Regional Hydrology
The study area is in typical Mojave Desert environment. The climate
of the region features low humidity, little but intense precipitation, and high
summer temperature. Potential evapotranspiration is high with a mean
annual lake evaporation of about 1.8 m. Mean annual precipitation is about
10 cm. Due to the short, steep gullies and high intensity thunderstorms,
runoff results in many flash floods. However, all the streams are ephemeral
and flow only during long duration or high intensity storms.
Based upon the little data available concerning the general area, a
rough approximation of the 50-yr peak discharge for various size drainage
areas has been made. Figure 2.4-8 of Ref. 2-1 was prepared by extra-
polation of data for areas 1035 km and larger. For small drainage areas
2-33
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2.5
2.0
CA
UJ
I
o
§ 1.5
z
1.0
0.5
IflllEY
ENERGY SYSTEM
10
12
DURATION (HOURSI
Figure 2-4. Rainfall depth, duration, and frequency curves.
2-34
-------
such as are found within the study area, local intense thunderstorms can
cause flood peaks greater than those shown in that figure. Onsite drain-
age systems should use the precipitation data from the depth-duration -
frequency curves shown in Figure 2-4.
A discussion of groundwaters appears in Section 2.3.
2.7 CLIMATOLOGY, METEOROLOGY, AND AIR QUALITY
Note: A detailed discussion of these subjects, including site-specific
field data, is beyond the scope of this project, and in any event appears in the
Harry Allen assessment (Refs.2-1). Nearly all of the following material
was extracted from that reference. We have excluded all meteorological
and air quality data relevant only to fossil fuel plants.
Data Collection
Hourly weather observations have been made at the present location of
McCarran International Airport, 662 m above MSL since 1948. Hourly records
began at Nellis Air Force Base in the early 1940s. The elevation of Nellis
AFB is approximately 85 m below the observation point at McCarran Airport.
Weather records at the nuclear test facilities at Yucca Flat began in
the early 1960s. However, the elevation of the Yucca Flat climatic station
is 1197 m above MSL as compared with 662 m at McCarran Airport.
General Climatological Description
The area within a 96 km radius of Las Vegas consists of broad valleys
surrounded by mountain ridges. The larger valleys contain dry lake col-
lection basins at elevations slightly less than 610 m above MSL. High moun-
tains, particularly to the west, have peaks above 3355 m and extended ranges
of terrain higher than 2135 m above MSL. Since mountains encircle the
various valleys, drainage winds are usually downslope toward the center, or
lowest portion of each of the broad valleys. This condition also affects
2-35
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minimum temperatures, which in lower portions of the valleys can be from
8 to 14 C colder than recorded at McCarran Airport on clear, calm nights.
Rainy days average from less than one in June to less than three per
month In winter months. Snow rarely falls in the valleys surrounding Las
Vegas and it usually melts as it falls, or shortly thereafter. Monthly cli-
matic data of precipitation and temperature are presented in Table 2-14 for
McCarran Airport. The arithmetic average of monthly precipitation re-
sults in annual total of nearly 10 cm at McCarran Airport.
Tonopah Lows are unique features of weather patterns in Nevada.
These low-pressure centers form in Central Nevada after a deep storm
center moves from west to east across the Pacific toward the California
coast. However, it is almost impossible to follow any low-pressure center
moving across California prior to the formation of the new low center in
Nevada. While the center is located to the west or northwest of Las Vegas,
strong winds from the southerly direction are recorded at McCarran Air-
port. After the center passes, the airflow shifts to the westerly components.
The intense surface heating during peak summer months creates a
semipermanent location of a low-pressure center, which is intensified each
day during afternoon hours in the western part of Arizona and the south-
eastern portion of California. This thermal low pressure center creates an
identifiable flow pattern which moves air cyclonically around the center of
this low.
The relative absence of major storm systems moving through the Las
Vegas area permits a high fraction of hours when calm wind conditions are
recorded. The monthly percentages of hours when calm wind conditions
exist are recorded at both McCarran Airport and Nellis Air Force Base.
Summarized surface wind data appear in Table 2-15 for four local stations
identified in Figure 2-5. During winter months, the longer hours of dark-
ness and the creation of a pool of relatively stagnant cool air near the ground
helps sustain a higher number of calms.
2-36
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NJ
U>
TABLE 2-14. AVERAGE MONTHLY PRECIPITATION AND TEMPERATURE VALUES
AT McCARRAN INTERNATIONAL AIRPORT, LAS VEGAS, NEVADA
(1937-1973), (ELEVATION 659 m ABOVE MSL)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Precipitation, ^
Arithmetic Mean, in?
Precipitation, 37-
Year Median, in.
*
Temp., F, avg. max.
Temp., F, avg. min.
Temp., F, mean
Temp., F, highest
Temp., F, lowest
0.44 0.37 0.41 0.25 0.13 0.08 0.41 0.47 0.35 0.25 0.40 0.36 3.92
0.22 0.14 0.22 0.07 0.06 Tr. 0.23 0.25 0.01 0.07 0.22 0.23
55.7 61.3 67.8 77.5 87.5 97.2 103.9 101.5 94.8 81.0 65.7 56.7 79.2
32.6 36.9 41.7 50.0 59.0 67.4 75.3 73.3 65.4 53.1 40.8 33.7 52.4
44.2 49.1 54.8 63.8 73.3 82.3 89.6 87.4 80.1 67.1 53.3 45.2 65.8
75 83 91 96 106 115 116 113 107 99 85 72 116
8 19 23 32 40 51 62 56 46 26 27 15 8
1 in. = 2.54 cm.
**0.555 (°F-32) =
-------
TABLE 2-15. SUMMARY OF SURFACE WINDS*
Speed
Categories
Knots**
1 0-3
2 4-6
3 7-10
4 11-16
5 17-20
6 21
Base
Station,
%
20.7
33.0
31.5
10.8
3.2
0.8
Pump
House
%
50.8
17.5
16.7
9.1
4.6
1.2
California
Wash,
%
42.3
23.8
14.7
10.3
6.2
2.6
Powerline
Bend
%
52.7
19.8
14.6
8.0
3.3
1.4
i
'?
Data by Desert Research Institute, University of Nevada, as reported in
,Ref. 2-1.
*1 knot = 1.852 km/hr.
HIDDEN VALLEY
(Base STat ion
MAIN STATION
(Pump House)
POWERLINE
BEND
.CALIFORNIA
WASH
Figure 2-5.
Location of meteorological stations surrounding
the Dry Lake site (cf. Table 2-15).
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A high frequency of calms can be expected in any dry lake area for
wind measurements made near the ground. Such calm conditions would per-
mit a high thermal rise to any plume emanating from a pollutant source. In
many instances, material in the plume would move upward and away from the
source within synoptic airflow that nearly always prevails above the surface
stable layer.
On the other hand, an examination of 1973 wind measurements at
McCarran Airport indicates that there were 520 hours when winds were 33
km/hr or greater. There are two important direction ranges for strong winds.
The highest frequency occurs in the direction range 200 through 230 deg with
a secondary peak extending from 320 through 340 deg.
Stability Climatology
In the Las Vegas area, there is a daily cycle of stability that repeats
itself almost every day in the year. There is a layer of stable air near the
ground during night and early forenoon hours, followed by neutral or unstable
conditions in the afternoon and early evening hours. A layer of stable air
near the ground occurs at 0400 PST on over 84% of all days per year. On
10% of the mornings, there is no inversion. These findings are based on a
5-year analysis of vertical temperature profile data measured by radiosonde
techniques at the McCarran Airport.
The same 5-year summary covering afternoon temperature profiles at
McCarran Airport shows only 10 instances where there were surface-based
inversions below 500 m. This would be a frequency level of only twice per
year.
It is evident that the early morning surface-based inversions are eli-
minated almost every day throughout the year. The corresponding changes
in stability within each 24-hour period would move from stable to neutral
and/or unstable, then back to stable. There would be almost no cumulative
pollution build-up into subsequent days. The depth of the stable layer may
be relatively shallow at the proposed site. Detailed vertical temperature
2-39
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soundings will be needed to establish a frequency pattern. Care must be
taken when the foregoing is viewed with respect to pollutant dispersion from
the proposed site since it is to be some 48 km from McCarran Airport in
Las Vegas and is in vastly different topography.
Meteorology
Data collected on a routine basis consists of continuous surface
meteorological and air quality data, upper air winds from the daily pibal
observations, and temperature sounding data taken by aircraft every third
day. The evaluation and analysis of these data is made with the purpose of
establishing normal or background characteristics for the meteorological
and air quality description of the siting area.
Surface Meteorology
Wind speed and direction plus temperature data have been taken at four
sites. Humidity, net radiation, and precipitation data have been taken at two
sites: Hidden Valley (Base Station) from August through November 1974 and
Main Station (Pump House) from December 1974 through June 1975.
The temperature data taken at the various sites shows the anticipated
march of temperature throughout the year. The summer months are ex-
tremely hot with most days exceeding 40 C. During the fall months the tem-
perature gradually decreases so that during the winter the average temperature
is fairly cool, around 20 C,
Radiation
The measurement of net radiation has been made at the sampling sites
described above, from August 1974 through June 1975. These data are of
interest in determining cloud cover and the total net amount of the incoming
minus outgoing radiation. The records show that on most days, the maxi-
mum amount possible of solar radiation has been received at the air quality
measurement site due to the general absence of clouds. On very few days,
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the records show low values of net radiation associated with low clouds and/
or continuous precipitation.
Relative Humidity
Relative humidity (RH) in southern Nevada is normally low. Measure-
ments at the Base Station and Pump House stations (Figure 2-5) show that
RH > 50% only 16.4% of the time. Summer RH rarely exceeds 35 to 40%. In
fall through spring, RH > 65% only 8 to 10% of the time. Occasional visi-
bility limiting ground fogs persist for several days.
Air Quality and Visibility
Air quality and visibility measurements were performed by Nevada
Power's consultants from August 1974 through June 1975 to determine the
background levels of various pollutants in the area of the Harry Allen Sta-
tion site (Ref.2-1). The following contaminants were monitored continuously.
• Sulfur Dioxide (SO_) • Total Hydrocarbons (THC)
• Oxides of Nitrogen (NO ) • Methane (CH.)
Jv ^t
• Nitrogen Oxide (NO) • Carbon Monoxide (CO)
• Nitrogen Dioxide (NO-) • Visibility
• Ozone (O_)
Manual sampling for total suspended particulates (TSP), SO_, NO_, and NO
was also carried out. The manual sampling for TSP was the only method
acceptable by EPA for this pollutant. The gaseous contaminants, SO_, NO_,
and NO were also manually sampled to obtain 24-hr integrated samples to
confirm the continuous monitoring data. The data are summarized in Table
2-16. Dust storms caused by strong winds normally result in reduced visi-
bility and high concentrations of suspended particulates. However, the
visual range is normally between 80 and 130 km.
Baseline air quality for the proposed site was found to be at normal
background levels, representative of the undisturbed as well as unpopulated
southwest desert, except for the total hydrocarbons, methane and carbon
2-41
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TABLE 2-16. BACKGROUND CONCENTRATIONS OF VARIOUS
CONTAMINANTS IN THE AREA OF THE PROPOSED SITE
Contaminants
Particulates
SO,
NO
NO
°3
THC
CH4
CO
Mean
35 jug m~3
< 5 ppb
< 10 ppb
< 6 ppb
15-20 ppb
1 . 7 ppm.
1 . 5 ppm
1 . 2 ppm
Peak 24 -hr
Average
405 jLAg m"
< 5 ppb
17 ppb
32 ppb
—
—
Peak 3-hr
Average
—
< 20 ppb
—
7.4 ppm
7.1 ppm
3.4 ppm
monoxide. Measured concentrations of total hydrocarbons, methane and
carbon monoxide are all well above normal background levels. The reason
for these higher concentrations is largely uncertain. They are not attributable
to traffic on Interstate 15, the Union Pacific Railroad, the Reid-Gardner Station
or Las Vegas urban plume, because there are no corresponding higher levels
of oxides of nitrogen and ozone. Their relation to industrial sources in East
Las Vegas is not known.
2.8 AMBIENT NOISE
Ambient noise measurements were performed at five stations by
Nevada Power consultants (Ref. 2-1) during the week of April 28, 1975. The
data, collected for one week only, were considered adequate to provide a
description of the ambient noise environment at the proposed site and at the
nearest residence. The latter is on U.S. Highway 93 at the south edge of
Unit 1 of the proposed solar electric site.
Non-related intrusions (military jet aircraft flyover, and highway
traffic) are subject to administrative and socio-economic changes beyond
the control of project proposers. Noise levels due to these intrusions
therefore, cannot be projected quantitatively. Nuclear test shots at nearby
Yucca Flats are a seismic but not an appreciable noise source.
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Statistical analyses of the A-weighted noise levels provides a method
of quantifying the outdoor noise levels. These analyses can provide the
cumulative noise level, that is an estimate of the level that is exceeded for a
percentage of the time. The cumulative levels presented are L-, L>,0, L^,
Lqn (the level exceeded 1, 10, 50 and 90%, respectively). The ambient noise
is the residual level when no identifiable noise sources are present. The
A-weighted noise level exceeded 90% of the time (Lqo) is used to describe
the ambient noise level.
The U.S. Environmental Protection Agency has chosen the A-weighted
energy equivalent average level, L (equivalent sound level), and the A-
eq
weighted equivalent day-night level, L, , as adequate reporting systems for
identifying and quantifying the environmental noise. The L, is the 24-hr
equivalent sound level with a 10 dB nighttime penalty.
The A-weighted cumulative distribution levels for each of the five loca-
tions are shown in Table 2-17. These levels are high for desert environ-
ments due to the frequent flyover of military jets taking off and landing at
Nellis Air Force Base and the traffic noise from Interstate Highway 15 and
U.S. Highway 93. Noise levels from jet aircraft flyovers in excess of 60
dBA were recorded. Noise due to 60-cycle hum from existing 230 and 500
kV transmission lines was not identified, and is apparently overwhelmed by
traffic noise on highways sharing the transmission line corridor. The noise
environment on the proposed site can be described as typical of rural en-
vironment with frequent intrusions due to military jet aircraft flyovers.
2.9 ECOLOGICAL SETTING
by W. Glen Bradley
The ecological evaluation of any area requires not only detailed inven-
tory and analysis of the area itself but a general knowledge of how this area
compares with and relates to the particular ecological region or unit of which
it is a part. Of particular importance is how typical or characteristic is the
area being evaluated. The portion of the Harry Allen Study Area corre-
sponding to proposed and alternate hypothetical solar-electric plant sites are
compared with southern Nevada specifically and with the northern Mojave
2-43
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TABLE 2-17. AMBIENT NOISE LEVELS AT MONITORING
LOCATIONS SURROUNDING UNIT 1
Sta.
Geographic and
Environmental
Description
Major Noise
Sources
Statistical Sound
Ll L10L50L«
Levels, dBA
90 dn
Open desert.
Nearest residence
3.2 km. West edge
of Unit 1 on dirt
road 0.8 km from
U.S. Hwy. 93
Military jet air-
craft flyover
53 39 30 26 46 51
Highway intersection
on North edge of
U.S. 93 right of way
90 m west of IS 15
Traffic; military
jet aircraft
flyover.
68 62 48 36 --
Southwest edge of
Unit 1
Nearest residence
0.8 km away. On
edge of U. S. 93
right of way
Traffic; military
jet aircraft
flyover
71 52 37 26 58 63
Open desert inside
Unit 1
Nearest residence
4 km away. Next
to dirt road remote
from traffic
Military jet
aircraft
flyover.
58 39 30 24 49 51
30 m west of West
Frontage Road
along Hw. 19 ~1.7
mic from U.S. Hwy.
93 almost under 500
kV transmission line
Traffic; military
jet aircraft
flyover.
67 58 48 37 56 63
For explanations of statistical noise levels, refer to document, "A Brief
Explanation of 'A-weighting' and 'Statistical Analyses of Noise Levels',"
adapted from Community Noise, PB-207-124, EPA, Washington, D.C.,'
1971, and U.S. Environmental Protection Agency, "Information on Levels
of Environmental Noise Requisite to Protect Public Health and Welfare "
550/9-74-004, March 1974.
dB re 20 micropascals.
2-44
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Desert generally. Data for regional analysis were obtained from the litera-
ture especially as summarized by Allred et al. (Ref.2-5), Bradley and
Deacon (Ref.2-6), and Austin and Bradley (Ref.2-7). Judgments on the po-
tential occurrence of biota on the Study Area were based on the above cited
works, our extensive personal experience in southern Nevada and observa-
tions made to date on the Study Area.
Description of Region
Southern Nevada including Clark County and the lower elevations of
southern Lincoln and southeastern Nye counties are part of the northern
Mojave Desert. The Mojave Desert is transitional between the cold Great
Basin Desert to the north and the more southern, hot Sonoran Desert (Brad-
ley, Ref. 2-8). The Mojave Desert includes those portions of Nevada and
adjacent desert areas of California which intergrade with the lower eleva-
tional Sonoran Desert. Some authorities include the southwestern area of
Utah which occupies the Virgin River drainage and portions of Arizona ad-
jacent to Nevada.
The Mojave Desert region represents the southern part of the Basin
and Range Physiographic Province. The Basin and Range Province is char-
acterized by numerous north-south oriented mountain ranges accompanied
by valleys without external drainage. Most of these ranges, found within the
Mojave Desert, are below 3000 m elevation with much of the valley floor
above 610 m. Commonly as a result of internal drainage, well-developed
playas occupy the lowest portions of the valley floor. Desert vegetation is
well-developed at elevations up to 1830 m and on some of the smaller moun-
tain ranges, at higher elevations. Soils are commonly of a gray desert type
with proportions of rock, gravel, sand, silt and clay dependent upon location
along the elevational gradient. For example, the soils of alluvial fans
(bajada) are high in rock, gravel and sand, while the lower valleys are
largely made up of a sandy, silty loam. Silts and clays dominate playas
while localized sand dune areas may occupy the leeward side of valleys.
The Mojave Desert is characterized by hot summers. Winters are
relatively cold with nightly temperatures commonly below freezing.
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Precipitation patterns are erratic from year to year, usually varying be-
tween 5 and 25 cm per year for all but the highest elevations. Both tempera-
ture and yearly precipitation fluctuate greatly from year to year (Bradley
and Deacon, (Ref. 2-6). Snow is common at 1220 m and higher during late fall
and winter.
In southern Nevada several large mountain ranges extend to elevations
above 2440 m and have well-developed coniferous forests which are not char-
acteristic of most mountain ranges in the Mojave Desert. However, much of
the area is occupied by desert mountain ranges and associated valleys. The
region in the vicinity of Las Vegas has been studied in some detail and num-
erous ecological relationships have been documented.
Biotic Associations of Southern Nevada
Natural groupings of populations of plants and animals occupying a
given area are classified ecologically as biotic communities, Responding to
environmental gradients, they occur as vegetation zones which are especially
steep and obvious in areas with topographical diversity, as in southern
Nevada. In desert regions the environmental gradient is largely influenced
by precipitation and temperature patterns which greatly modify water avail-
ability, which is the major regulatory factor in desert ecosystems. In turn,
animals which depend upon vegetation for food, shelter and other require-
ments for life, show similar gradients in their distribution. Natural group-
ings of biota are recognized as communities because of the overlap of
tolerances of a large proportion of the biota to various environmental
factors. Because of nonoverlap in tolerances to certain environmental phe-
nomena, both within and between community variation exists to a lesser or
greater degree.
The major terrestrial biotic communities of southern Nevada have been
generally described (Bradley and Deacon, Ref. 2-6). The major community
found at lower elevations occurs throughout the proposed solar-electric plant
site.
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Cresote Bush Community: The Creosote Bush Community is the most
extensive and widespread community of the southern North American deserts
(Sonoran, Chihuahuan, and Mojave). In southern Nevada it is well-developed
throughout the lower elevations to 1280m and higher on south facing slopes
and on small isolated mountain ranges.
The topography ranges from valley floors to lower bajadas and in some
areas includes very rocky and rugged terrain. The general topography is
dissected throughout by desert washes and interrupted by small hills and low
mountain ranges.
Typical soils are gray, rocky alluvium without soil horizons, slightly
alkaline and with a salt content usually < 0.5%. Often there is a hard sub-
surface layer of caliche. Many areas are overlain with desert pavement.
Plants; Throughout this community the vegetation is typified by
Creosote Bush and Burro Bush as the dominants. These usually occur to-
gether but occasionally occur in almost pure stands. Yuccas, primarily
Mojave -Yucca are common associated plants especially on bajadas. Other
shrubs usually associated with this community are Krameria parvifolia,
Parosela spp., Atriplex supp., Ephedra nevadensis, Salvia spp., Encelia
farinosa, Thamnosma montana, Mendora spinescens, Psilostrophe cooperi,
Lycium spp., and Eriogonum spp. In some areas cacti, especially prickly
pears and chollas (Opuntia spp.), Barrel Cactus and Hedgehog Cactus are
common.
Large numbers of species compose the herbaceous vegetation, the
most common of which are composites, mustards and legumes. These vary
considerably from year to year in density, size and species richness being
most prominent in years of high precipitation when they cover the desert
floor.
Reptiles and Amphibians; Reptiles, especially lizards, are wide-
spread, abundant, and commonly observed in this community. The more
abundant lizards include Desert Crested Lizard, Zebra-tailed Lizard,
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Side-blotched Lizard, Desert Horned Lizard, and Western Whiptail. The
more common snakes include Common Whipsnake, Gopher Snake and Side-
winder. The Desert Tortoise is frequently observed in this community.
Occasional amphibians are found in this community but are considered to
belong to adjacent more mesic communities.
Birds: Of the birds occurring here, very few are common. Most
species recorded belong to adjacent riparian communities and are not part
of the Creosote Bush community avifauna proper. Most species of this
community reach their greatest abundance on the bajadas in association with
yuccas. The more abundant species throughout the community include
Horned Lark, House Finch, Black-Throated Sparrow and Sage Sparrow.
Species commonly associated with yuccas include Ladder-backed Wood-
pecker, Ash-Throated Flycatcher, Cactus Wren, Loggerhead Shrike and
Scott's Oriole. Occasional individuals of many species will use this com-
munity to forage during migration. Species from higher elevations may
occur during winter with considerable year to year differences in the species
present and in their abundance.
Mammals; Relatively large populations of several mammal species
are found in the Cresote Bush community. Common bats which utilize this
community include California Mouse-Eared Bat, Western Pipistrelle, Big
Brown Bat, Pallid Bat, Lump-Nosed Bat and Mexican Free-Tailed Bat.
Common and characteristic rodents include Antelope Ground Squirrel,
Round-Tailed Ground Squirrel, Merriam's Kangaroo Rat, Long-Tailed
Pocket Mouse, Little Pocket Mouse, Desert Wood Rat, Canyon Mouse and
Cactus Mouse. The Black-Tailed Jackrabbit is widespread and common.
The only common mammalian predators are the Coyote, Badger and foxes.
Larger herbivores are rarely seen.
Adaptations of Desert Biota
The following discussion is a generalized account of the major strat-
egies utilized by biota for desert existence. Much of the literature on desert
2-48
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adaptation has been recently summarized in volumes edited by Brown
(Ref. 2-9).
An organism's ability to exist in the desert is determined by its ability
to maintain favorable water balance and suitable temperature range as all
vital processes occur in an aqueous medium within a temperature range spe-
cific for any particular organism. Extreme temperatures coupled with high
evaporation rates and scarcity of water are responsible directly or indirectly
for the adaptations exhibited by desert organisms. Both distribution and
abundance of desert biota depends largely on behavioral and/or physiological
adaptations which allow organisms to achieve homeostasis.
Many desert shrubs exhibit a uniform widely spaced dispersion pattern,
thus limiting extreme competition for water. In Creosote Bush, for example,
root secretions are produced which inhibit germination of other Creosote
Bushes in the near vicinity. Certain desert plants display root systems that
intercept different water sources in the soil profile. Shrubs and trees such
as Desert Willow and Mesquite are found along desert washes. Here, elon-
gated root systems, sometimes extending down to 12 m, tap the underground
water sources. Succulents such as yuccas and cacti have shallow root sys-
tems that extend just below the surface of the ground. This enables these
plants to utilize low precipitation and near surface runoff.
Succulents are noted for their capacity to store water. This is an
apparent adaptation to ensure sufficient water necessary for metabolic
processes during periods in which a dependable water supply is not avail-
able. Also, certain leaf characteristics such as reduced size, thick cuticle,
leaf hairs and reduced or sunken stomata have been considered as impor-
tant morphological modifications to retard water loss.
Desert vegetation is dominated by seemingly lifeless shrubs which dis-
play active growth for brief periods. This dormant condition is character-
ized by extreme dehydration and low metabolic activity. Dormancy
accompanied by a tolerance for dehydration is highly developed and is the
major adaptation which enables perennial plants to exist in the desert.
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The ability of seeds to survive environmental extremes is well known.
As seeds, the dormant condition may be extended over several years. When
suitable conditions appear, germination, growth and corresponding metabolic
activities occur. Desert annuals, known as ephemerals, develop from seeds
during those brief periods when the desert environment is altered by pre-
cipitation. During these favorable periods, as metabolic activities increase,
vegetative growth is kept at a minimum while flowering and seed production
is emphasized. In these dwarf plants the complete life cycle may be com-
pleted in as short a period as three weeks. Chances for survival of the
individual plant is enhanced by very precise conditions for germination.
Behavior, especially activity patterns which limit activity to the most
favorable daily and seasonal periods is the major adaptation employed by
desert animals (Bradley and Yousef, Ref. 2-10). This is most clearly shown
as daily activity patterns such as diurnal, nocturnal, crepuscular and daily
dormancy or seasonal patterns such as migrations and hibernation (seasonal
dormancy). It is obvious that the major behavioral strategy involved in these
activity patterns is the avoidance of environmental extremes.
Dormancy, which is a major adaptation in desert plants, is also a
major strategy used by many vertebrate and invertebrate groups. This is a
special case of physiological specialization accompanied by behavioral
avoidance. Each terrestrial vertebrate group, therefore, employs a par-
ticular combination of adaptive physiological and behavioral strategies which
determines their distribution and survival.
Amphibians have a limited distribution in deserts with the more
aquatic forms restricted to riparian habitats. Terrestrial forms, par-
ticularly Scapjviogus hammondi (Hammond's Spadefoot Toad) extends into
more arid regions, utilizing dormancy as the key to survival. Located in
underground burrows, they undergo gradual dehydration over long periods
of time. During these periods urine formation largely ceases and extreme
desiccation is possible. Adults recover water lost during dehydration by
absorption through the skin during and after periods of precipitation.
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Activity and breeding is restricted to areas around temporary pools after
summer rains.
Reptiles are poikilothermic, with body temperature approximating air
temperature. Necessarily, these organisms behaviorally alter their micro-
habitats and thus regulate their body temperature. Withdrawal into pro-
tected sites, both daily and seasonal, results in hibernation or aestivation
which increases survivability. Water is commonly ingested in the form of
succulent food although desert reptiles will utilize free water when available.
The cornified layer of scales retards water loss by evaporation. Nitrogenous
waste in the form of uric acid precipitate permits removal of body wastes
with minimal water loss. Reproductive efficiency is greatly facilitated by
the land egg with a thick shell which retards water loss.
Birds and mammals are homeothermic and regulate their body tem-
perature at relatively constant high levels, at least when active. Under tem-
perature extremes the common methods used to maintain body temperature
are changes in insulation, evaporative cooling or shivering and increasing
metabolic rate. Behaviorally, these animals utilize avoidance; birds re-
treating to shady areas and most mammals to cool burrows.
In birds, nitrogenous wastes are largely removed from the body as
uric acid precipitates. However, due to high breathing rates associated with
flight, evaporative water loss is great. It is doubtful if any bird can survive
without free water or succulent food. This accounts for depauperate breed-
ing avifaunas in low desert. Because of high mobility the major adaptive
strategy of birds include daily movements to watering sources and/or
seasonal migrations.
Mammals exhibit a wide variety of adaptive responses including dor-
mancy, hyperthermia and production of concentrated urine. Certain ground
squirrels aestivate during the summer which is the period of greatest scar-
city of green vegetation. Other rodents, particularly pocket mice, hibernate
in the winter when seeds are scarcest.
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A highly efficient kidney which produces concentrated urine is found in
antelope ground squirrels, pocket mice, kangaroo rats and certain bats.
Some of these animals such as Merriam's Kangaroo Rat and the Pallid Bat
are known to survive entirely without free water. Water conservation is
further enhanced by eating succulent foods and avoiding conditions of high
temperature and low water vapor pressure. The strategy of avoidance is the
most used as evidenced by the large number of nocturnal, burrowing animals.
A few mammals, such as antelope ground squirrels and desert sheep,
are diurnal and therefore forego a certain degree of avoidance. The antelope
squirrel utilizes metabolic water, succulent food and any available free
water. In addition, it concentrates urine and allows for hyperthermia or heat
loading. As body temperatures build up during the day, the heat load is lost
to the environment by movements into the shade or underground burrows.
By utilizing the many burrows scattered throughout the home range as tem-
porary shelters for dissipating heat, the animal can remain active during the
less extreme part of the day without major loss of water in thermoregulation.
The mechanisms which enable large mammals such as desert sheep to
survive in the desert are partially unknown. Domestic sheep have a concen-
trated urine, and preliminary indications reveal that Desert Bighorms
possess similar characteristics. Another large desert mammal, the Camel,
has concentrated urine, and a tolerance for extreme dehydration and hyper-
thermia. These specializations are to be looked for in the large American
desert mammals. Desert sheep occupy shady sites during periods of ex-
treme heat and travel long distances to water. At other times, they appear
to be able to go for as yet undetermined periods utilizing water from succu-
lent foods. This would suggest some tolerance for dehydration but would
indicate that these mammals restrict their range during warm seasons to
the proximity of free water.
Trophic Relationships
Detailed trophic relationships have not been documented for Mojave
Desert biotic communities. However, selected species have been studied in
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the Las Vegas area which allow some generalizations (Bradley and Deacon,
Ref.2-6; Bradley, Ref. 2-11; Bradley and Deacon, Ref. 2-12; Bradley and
Mauer, Ref. 2-13; Bradley, unpublished data)
Generalized data on the food habits of vertebrates are included in Sub-
section 1. A brief statement concerning trophic relationships is provided
below.
As in all ecosystems, the primary producers (green plants) form the
food base for animal populations. Herbivores include Desert Tortoise,
Desert Iguana, Chuckwalla, Black-Tailed Jackrabbit, Audubon's Cottontail
and Desert Bighorn Sheep. Of these, the Jackrabbit and Cottontail provide
the major browsing and grazing pressure on the desert ecosystem. Seed
eaters, especially rodents and some birds, are of potential importance in the
cropping of the rather abundant seed reserves found in deserts. For
successful reproduction most rodent species, however, are largely dependent
on spring production of annual vegetation which is consumed as green vege-
tation. This provides the added water supplement needed for pregnancy and
lactation and possibly estrogenic substances needed for the development of
reproductive condition. Both herbivore and seed eating components are con-
sidered primary consumers.
All of the other vertebrate species which rely chiefly on arthropod or
vertebrates for food are classified as predators and thus secondary or ter-
tiary consumers. In general, lizards feed on other lizards and arthropods
as a food source, whereas snakes feed chiefly on bird and lizard eggs,
lizards and small rodents. Considerable evidence indicates that the abundant
and diversified rodent fauna is the main food source for the larger snakes,
predatory birds and such carnivores as Coyote, foxes and Badger.
A realistic model of trophic relationships involves rather complex food
webs with many vertebrate species being opportunistic and relying on those
appropriate food sources within their general food preference which are
locally or seasonally available.
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Community Succession
Disturbance of desert communities by such activities as fire, removal
of vegetative cover and other activities associated with community alteration
by man can produce distinct changes, termed community succession. Desert
ecosystems are fragile, easily disturbed by human activities and are slow to
recover due to slow growth responses under the direct influence of low water
availability and poor soil development.
Vegetative succession is varied but usually relatively simple. In
areas far removed from human development with essentially natural vegeta-
tion, succession may involve serai stages of annual vegetation usually
associated with disturbed areas such as desert washes. However, since
nonnative species such as Russian Thistle, RedBrome and Cranesbill are
commonly available, succession is usually altered.
The first species to invade are usually Russian Thistle and Red
Brome. Following this, various annuals, especially types which are most
common in washes, invade. These include annual Eriogonum spp., Bromus
spp., Cranesbill and various mustards. Following this, such perennials as
Baileya, Hymenoclea, Gutierrezia and Sphaeralcea become established.
These three elements combine to produce serai stages of long duration,
probably in excess of 50 years. The exact details of return to the climax
community are unknown and would vary, depending upon location, however,
many areas of Mojave Desert have not recovered to climax state in approxi-
mately 100 years (1961). Vertebrate faunas of serai stages would be similar
to those found in climax communities. Animal populations would fluctuate,
however, during succession and in some species, densities would be higher
during serai stages of succession.
Biotic Associations of the Solar Electric Station Study Area
The physiography of the solar power station study area is typical of
low desert in southern Nevada. The valley floor slopes up into two low but
rugged mountain ranges (Dry Lake Range and Arrow Canyon Range), and to
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the east into the higher Las Vegas Range. The entire area is dissected by
numerous desert washes which drain the surrounding ranges. In some areas
the bajada is interrupted by low rocky knolls. On the valley floor there is a
relatively large dry lake.
The proposed hypothetical solar-electrical plant site is divided into
two sections; one to the southwest and the other to the northeast of Dry Lake
playa. The eastern boundary of both sections is adjacent to the Union
Pacific railroad tracks, whereas the eastern boundary is adjacent to the
Arrow Canyon Range. These two sections are similar in elevation, ranging
from approximately 610 to 720 m. The alternate site is continuous with the
northeastern portion of the proposed site, but extends further north. Eleva-
tions of the alternate site vary between 610 to 781 m with the exception of a
small mountainous area of 3 km located in the north-central portion.
This area, which rises to above 854 m, has uneven topography and
probably would not be utilized for solar-electric units.
The general description given for the Creosote Bush Community in
southern Nevada applies equally well to both sites. Small areas of Desert
Riparian Community are found along the washes. The vegetation along these
washes does include some species characteristic of washes, with individual
plants being larger and more numerous. Animals inhabiting these areas are
the same as those found in Creosote Bush Communities, although relative
abundance may differ.
Vegetation
All areas of the proposed and alternate solar-electric sites are com-
posed of Creosote Bush Community with Burrobush and Creosote Bush as
codominants. Due to the much smaller size in area of the proposed solar-
electric sites, exact numeration of species occurring cannot be obtained
from Appendix B= Subsection 1.1, (Ref.2-1), or the 1976 unpublished Appen-
dix B Update and Appendix I. It is estimated, however, that approximately 212
species (64%) of a potential 329 species occur on the proposed and alternate
solar-electric sites.
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Based upon reanalysis of 8 plant sampling stations located on the
southern portion of the proposed site, mean perennial plant cover was 2.3%
with a range of 1.5 to 4.0%. A total of 28 perennial and 39 annual species
occurred at these sampling stations.
Other than codominants, important perennial species ranked according
to their relative importance were Little-leaved Ratany, Nevada Mormon Tea,
Desert Mallow, Cooper Lycium, Spiny Mendora, and Cheese-bush.
Seven plant sampling stations located on the northern portion of the
proposed site and the expanded alternative site were reanalyzed. Plant cover
was more sparse and fewer plant species were found in these areas than on
the southern section of the proposed site. Mean perennial plant cover was
1.7%, ranging from 0.5 to 3.1%. Only 12 perennial species were found on the
sample stations. No samples of annual species were available for analysis
for these areas. The relative ranking of subordinate species was somewhat
different with Russian Thistle, Galleta, and Winterfat being important plant
species.
Vertebrates
The distribution of vertebrates found on the two proposed and alternate
solar-electric sites were analyzed based upon data found in Appendix B,
Subsections 1.2 through 1.5, and Appendix B Update, Appendix I (loc.cit).
Amphibians; No amphibians were found on any site, although one
species, Hammond's Spadefoot Toad, was found on Dry Lake playa adjacent
to the proposed and alternate sites.
Reptiles; Fifteen species of reptiles were found on the proposed and
alternate sites out of 29 which potentially occur in lower desert communities.
Of these one is a tortoise, eight are lizards, and six are snakes.
The Desert Tortoise is relatively common throughout the relatively
flat portions of the Study Area but is apparently absent on rock knolls, slopes
and ridges of the surrounding mountainous area.
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Two lizards, the Side-Blotched Lizard and the Western Whiptail, are
abundant and widespread throughout the sites. Zebra-Tailed Lizards are
"also widespread and common, especially along the courses of washes. In
the lower and more sandy portions of the area, especially on the northern
proposed and alternate solar-electric sites Desert Horned Lizards are
common. The remaining species of lizards (Desert Crested Lizard, Chuck-
walla, Collared Lizard and Leopard Lizard) are represented by 1 to 3 sight-
ings each and are to be considered uncommon on the sites.
The two most common species of snakes on the sites are the Common
Whipsnake and the Gopher Snake, each represented by several sightings.
These two species are considered the characteristic species of lower desert
areas. The remaining species (Common King Snake, Long-Nosed Snake,
Western Patch-Nosed Snake and Speckled Rattlesnake) are represented by
1 to 2 records each and are considered uncommon to rare on the sites.
All species of reptiles encountered to date are those that are to be
expected in the lower desert of southern Nevada. The relative abundance
and apparent densities of lizards are comparable to those of other similar
low desert areas of southern Nevada. Likewise, the two most common
snakes are also the most abundant in other low desert areas of the Mojave
Desert. It is surprising that the relatively common Sidewinder has not been
recorded on the sites to date. The Desert Tortoise is on the Nevada
Threatened Species List. Although its actual density on the Study Area is
unknown, the frequency of sightings indicate a relatively dense population.
In our opinion, however, this population is comparable in density to others
in southern Nevada; the species being rare only near population centers and
immediately adjacent to highways.
Birds: A total of 70 species (of a potentially occurring 90 species)
were found on the station study area. Most of these probably occur on the
proposed and alternate solar-electric sites. Of these 70 species, 23 were
permanent residents, 16 winter residents, 8 summer residents, 22 transients,
and 2 visitants. Permanent residents include the following: Red-Tailed
Hawk, Prarie Falcon, Sparrow Hawk, Gambol's Quail, Killdeer, Roadrunner,
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Burrowing Owl, Ladder-Backed Woodpecker, Say's Phoebe, Horned Lark,
Verdin, Bewick's Wren, Cactus Wren, Rock Wren, Mockingbird, LeConte's
Thrasher, Black-Tailed Gnatcatcher, Loggerhead Shrike, Red-Winged
Blackbird, Brown-Headed Cowbird, House Finch and Phainopepla. Nine
species (see p. 31, Appendix B Update) are known to breed on the station
study area.
The solar-electric sites are relatively impoverished in diversity
and numbers of birds of prey, with the most important commonly ob-
served species being the Red-Tailed Hawk. The only game species are
Gambel's Quail and Mourning Dove, both of which occur at low densities.
The Mourning Dove, however, is an uncommon nesting species on the
station study area. Other birds make up the majority of avifauna on the
area. In general, sparrows were the most numerous group throughout the
year, with Sage Sparrow dominant in winter and Black-Throated Sparrow in
summer. Population densities and biomass were greatest during early
•winter, decreased into late winter, increased in spring migration, and de-
clined to lowest levels in late summer. Species composition of birds was
as expected for similar areas in the northern Mojave Desert with low
densities and biomass which is characteristic of desert communities.
Mammals; A total of 24 out of a possible 37 species of mammals
have been recorded on the Harry Allen Study Area. Most probably occur on
the solar-electric sites. All species recorded are expected to occur in
similar habitat in the northern Mojave Desert. One species, the Spotted
Skunk, is quite uncommon away from riparian areas adjacent to water. Bats
(
are often seen in the evening and morning throughout the Study Area. The
Black-Tailed Jackrabbit is common throughout the Study Area; the Audubon's
Cottontail is common in the vicinity of the Dry Lake. Coyotes are the most
common predator on the Study Area, being distributed throughout. The Kit
Fox has been seen occasionally in the lower areas of the Study Area es-
pecially near the Dry Lake. The Bobcat was observed once crossing a
highway. Desert sheep commonly occur throughout much of the Arrow
Canyon Range but seldom utilize the area of the proposed and alternative
solar-electric sites.
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Rodents comprise the largest group of mammals using the proposed
and alternate solar-electric sites. Common to abundant species include
Merriam's Kangaroo Rat, Long-Tailed Pocket Mouse, Little Pocket Mouse,
Antelope Ground Squirrel, and Desert Deer Mouse. All rodent species
found were characteristic and representative of similar low desert com-
munities.
Concluding Remarks
The vegetative composition of the proposed and alternate solar -
electric sites are characteristic of Creosote Bush Communities in southern
Nevada. Vegetation similar in species composition and other vegetative
features are continuous and widespread at elevations below 1220 m through-
out the Mojave Desert. Similarly, vertebrate animals including reptiles,
mammals, and resident birds are all characteristic inhabitants of these
widespread communities. Due to their high mobility, large numbers of
migratory birds characteristics of more mesic environments temporarily
inhabit desert areas for varying periods of time.
No plants known from Harry Allen Station Study Area are considered
to be rare or threatened. Two reptiles, the Desert Tortoise and Gila
Monster are included on the state list of threatened species. The Desert
Tortoise is relatively common to the Study Area as well as other low desert
areas of southern Nevada. In our opinion, it is neither rare or endangered
except possibly in the near vicinity of population centers or immediately
adjacent to highways. The Gila Monster is listed as potentially occurring
on the Study Area although none have been observed. The Gila Monster is
usually associated with larger more mesic washes or river drainages but
possibly could occur on or near the playa.
No birds found to date on the Study Area are classified as threatened
or endangered. Nearly all species recorded, however, are protected by the
federal Migratory Bird Treaty Act. Most others, hawk-like birds, Road-
runner and Owls are protected by state law. Two species, Gambel's Quail,
and Mourning Dove are game birds in Nevada.
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Two mammals, Spotted Bat and Kit Fox are on the state protected list
and are considered rare. The Spotted Bat is listed as potentially occurring
on the Study Area. The Spotted Bat prefers coniferous forests and usually
is not encountered at the lower elevations in the desert except in riparian
habitats. The few records for this highly habitat specific and highly secre-
tive bat for the Las Vegas Valley are based upon sick or dead individuals.
If present, utilization of the Study Area by this species is minimal.
The Kit Fox has been observed repeatedly on the Study Area. It is
still common in many low desert areas of Nevada and is becoming rare only
near population centers such as Las Vegas Valley where suitable habitat has
been greatly altered.
In summary, of the four threatened or protected vertebrate species,
only two, Desert Tortoise and Kit Fox, are found on the Study Area in appre-
ciable numbers. Both are widespread and occur at comparable densities in
suitable habitat which is widespread in other areas of low desert in southern
Nevada.
2.10 ARCHAEOLOGICAL AND HISTORICAL SITES AND NATIONAL
LANDMARKS
Archaeology
Consultants for Nevada Power (Ref.2-1) established a study area in-
cluding all of T.17S, R.63E and T.18S, R.63E, as well as those portions of
T.17S, R.64E inside the Dry Lake depression. This study area therefore,
comprises much more than Unit 1 of the proposed site, but only insignificant
portions of Unit 2. The latter, for all practical purposes, remains to be
studied.
The survey included a re examination of four previously recorded
archeological sites within, or adjacent to, the study area.and a determination
of whether additional archeological remains exist in the area.
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The survey was conducted in accordance with Federal standards for
mitigation of impact of construction activities on archeological resources on
public lands. The survey was carried out under appropriate Federal and
State of Nevada antiquities permits.
Literature and Record Search
A search was made of all published archeological literature, including
the National Registry of Natural Landmarks for the study area. No refer-
ences were found pertaining to archeological sites in either study area. The
unpublished archeological site records of both the University of Nevada, Las
Vegas Natural History Museum, and the Overton State Museum, Overton,
Nevada, were searched. For Unit 1, the excavation notes for the Flaherty
Site were found. As indicated below, the site is on the edge of Unit 1 in the
NE1/4 of T.18S, R.63E. The site was previously excavated.
Field Surveys
For the areas, pedestrian surveys were conducted. For Unit 1, U.S.
Highway 93 was used as a baseline. Transects spaced 100 m apart were laid
out and walked from the highway to the western boundary of the area. Sur-
veyors were spaced 15 to 20 m apart. Particular attention was given to cut-
banks, drainage channels, and knoll tops. Low buttes with known small
rockshelters were also checked. These are located at the south end of
Area 1. One small, culture-bearing rockshelter was recorded and tested
(see below). Others proved negative.
Testing Technique
In the two tested rockshelters, standard testing techniques were used.
One meter square test pits were laid out, both inside and outside the shelter
driplines. The test squares were excavated by trowels in 10-cm levels.
All materials were passed through 1/4-in. (6.3 mm) wire mesh screens.
Recovered artifacts were recorded by square and level.
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Results
No surface sites or rockshelters were found within or near to Unit 1.
History
A survey of the National Register of Historic Places was conducted to
determine the historical significance of the Dry Lake area approximately
40km northeast of Las Vegas, Nevada. Literature on southern Nevada is
scarce, especially for the period before 1905 when the San Pedro-Los
Angeles-Salt Lake City Railroad (Union Pacific) was built.
The Old Spanish Trail and Mormon Wagon Road run parallel to old U.S.
Highway 91 and are of historical significance, not only to southern Nevada,
but to the west as a whole. There is a sign commemorating the trails at the
junction of Interstate Highway 15 and U.S. Highway 93.
The San Pedro-Los Angeles-Salt Lake City Railroad was completed on
January 30, 1905. Until the construction began, there was little, if anything,
in the way of settlements between Las Vegas and Moapa. There is evidence
of a railroad work camp that can be seen today in T.17S, R.64E, Section 8.
Such communities as Dry Lake and Garnet are close to the station sites.
Today, no one lives at Garnet, although the remnants of structures can be
distinguished. Dry Lakes population usually consists of three families,
although it appears there was a large community at one time. Dry
Lake had a U.S. Post Office from December 3, 1925, until June 30, 1945,
and again from January 31, 1950, until December 31, 1955. There is also
some word-of-mouth information that a school was located in Dry Lake in
the late 1930s. The community probably serviced not only the railroad but
also the surrounding mines.
In reference to present-day mining activity in the area, there is a
rather large operation at Apex. United States Lime Products Division of the
Flintkote Company owns and operates a limestone quarry and a crushing and
calcining plant that produces approximately 450,000 MT annually.
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National Landmarks
No designated National Landmarks or National Monuments occur
within or near either Units 1 or 2.
Conclusions
The area to be occupied by Unit 1 contains no archaeological sites.
The Old Spanish Trail and Mormon Wagon Road run parallel to the old
Highway 91 right of way. Such portions of these trails as still exist and
seem to have historical value can be excluded from the plant area.
Unit 2 has not been investigated. A parallel study of that area would
be required.
2.11 VISUAL VALUES
A scenic value and visual impact study of Units 1 and 2 and the entire
surrounding region appears in Ref. 2-1. In summary the entire area, en-
visioned for the plant is described as "below average" in scenic quality.
Some nearby areas, particularly the Desert Canyon range, are described
as "above average." Some of this range is visible from Interstate Highway
15 and U.S. Highway 93, in perspectives which would place the hypothetical
proposed solar generating station in the foreground.
2.12 REFERENCES
2-1. Nevada Power Company. Environmental Assessment, Allen-Warner
Valley Energy System, Volume III, Harry Allen Station, September
1975, and Appendices Volume to Volume III. Las Vegas, Nevada,
September 1975.
2-2. Rooke, Lloyd, Soil Conservation Service, USDA, Las Vegas, Nevada.
Private conversation with D. Richard Sears, Lockheed-Huntsville,
June 1976.
2-3. Arlidge, John W., Nevada Power Company, Las Vegas, Nevada.
Private conversation with D. Richard Sears, Lockheed-Huntsville,
June 1976.
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2-4. Hammond, A.L. Lithium: Will Short Supply Constrain Energy Tech-
nologies? Science, Vol. 191, 1976, p. 1037.
2-5. Allred, D.M., D.E. Beck, and C.D. Jorgensen. Biotic Communities
of the Nevada Test Site. Brigham Young University, Science Bulletin,
Biology Series, 1(2): 1-52, 1963.
2-6. Bradley, W.G., and J.E. Deacon. The Biotic Communities of South-
ern Nevada. Nevada State Museum Anthropological Papers, No. 13,
part 4:201-295, 1967.
2-7. Austin, G. T., and W.G. Bradley. The Avifauna of Clark County,
Nevada. Journal of the Arizona Academy of Science, 6:283-303,
1971.
2-8. Bradley, W.G. A Geographical Analysis of the Flora of Clark
County, Nevada. Journal of the Arizona Academy of Science,
4:151-162, 1967.
2-9. Brown, G.W. Desert Biology: Special Topics on the Physical and
Biological Aspects of Arid Regions. 2 Volumes, Academic Press,
New York, 1968 and 1974.
2-10. Bradley, W.G., and M. K. Yousef. Small Mammals in the Desert.
Pages 127-142 in M. K. Yousef, S.M. Horvath, and R. W. Bullard
(eds.). Physiological Adaptations: Desert and Mountain, Academic
Press, New York, 1972.
2-11. Bradley, W.G. Food Habits of the Antelope Ground Squirrel in
Southern Nevada. J. Mamm., 49; 14-21, 1968.
2-12. Bradley, W.G., and J.E. Deacon. The Ecology of Small Mammals
at Saratoga Springs, Death Valley National Monument, California.
Journal of the Arizona Academy of Science, 6:206-215, 1971.
2-13. Bradley, W.G., and R.A. Mauer. Reproduction and Food Habits of
Merriam's Kangaroo Rat, Dipodomys Merriami. J. Mamm. 52-
497-507, 1971.
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SECTION 3
RELATIONSHIP OF THE PROPOSED ACTION TO LAND USE PLANS
POLICIES, AND CONTROLS FOR THE AFFECTED AREA
3.1 CLARK COUNTY REGIONAL PLANNING COUNCIL
The Clark County Regional Planning Council has published no plans or
controls for this land which vvould preclude the proposed action.
3.2 BUREAU OF LAND MANAGEMENT PLAN
The Bureau of Land Management (BLM) has developed a "Framework
Plan," and documentation is available for inspection in the BLM Las Vegas
office.
Among established land use plans, policies, and controls affecting this
site, as collated and enunciated by the BLM, the following seem relevant.
Off-Road Competition
The BLM has designated this area as appropriate and authorized for
off-road vehicle competitions. An off-road course has been laid out running
from Crystal, on old U. S. Highway 91, under Interstate Highway 15, through
Unit 2, west of the Dry Lake depression, and thence through Unit 1. An en-
vironmental assessment has been performed for this activity, and is avail-
able for inspection at the BLM Las Vegas office. In recent years, organized
competitions have been staged which involved as many as 400 to 500 dune
buggies and 200 to 300 motor bikes. This activity is destructive of vegeta-
tion, but certainly not to the extent that the proposed plant construction
would be.
3-1
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Continued off-road vehicle competitions in or near the solar genera-
ting station site, Units 1 and 2, would have to be prohibited, in order to avoid
accelerated losses in generating capacity due to dust burdens on reflectors.
Agreement to this effect would be required from BLM before a go-ahead
decision could be made for this proposed action.
Sewage Effluent Lagoon
The city of Las Vegas has studied the possible use of the Dry Lake
depression for a sewage plant lagoon. This use of the depression, while
aesthetically offensive, would not necessarily affect solar station operation
adversely.
Power Transmission Corridors
Powerline corridors exist in the area now, and additional ones are
planned. Existing corridors are advantageous to plant design; additional
corridors would have to be established in coordination with plant designers.
If proper coordination occurs, there need be only minimal adverse effect
on plant layout.
Power Plant Siting and Pipelines
Unit 1 has been determined to be an appropriate site for a 2000 MW coal
fired power plant. There would be an associated buried coal slurry pipeline
bringing 174 x 10 m slurry water front Southwest Utah. The latter might
run through Unit 2, A tertiary sewage effluent pipeline from N. Las Vegas
Q 3
would bring 1.18 x 10 m of fluid to Unit 1.
It is possible that the proposed action could be located in the alternate
site, perhaps largely in Unit 2, notwithstanding the presence of a coal fired
plant in Unit 1. Very careful atmospheric dispersion estimations, and
field opacity measurements, would have to precede a go-ahead decision.
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Mining Claims
There is one mining claim in Unit 1: Old Witch Mining No. 1, owned
by Hugh Issaacs, in T.18S, R. 63E, Section 11. This is about 1.6 km west of
Interstate Highway 15, just northeast of U.S. Highway 93. Neither its value
nor its validity have been investigated by BLM. The identity of the claimed
mineral resource is not known to BLM. A shaft or drift mine at that location
would not necessarily be inconsistent with the proposed solar generating
station. A strip mine at that location would probably prevent utilization of
a significant fraction of Unit 1 for the proposed power plant, but would not
preclude plant construction further north.
Two mining claims exist adjacent to but not in, the alternate site out-
side of Unit 2. These are:
Mamie Nos. 1 and 2 Placer, owned by Clarence
Grant, and located in T.16S, R.64E, Section 7.
Piute No. 9, owned by R. F. Barnal, and located
in Section 6.
The nature of potential mining activities at those claims is not known. They
both appear to be at high elevations in the Arrow Canyon Range. Any dust
producing activity there could be avoided easily, since the alternate site is
very much larger than our requirements.
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SECTION 4
PROBABLE IMPACT OF THE PROPOSED ACTION
ON THE ENVIRONMENT
4.1 ECOLOGICAL IMPACTS
by W. Glen Bradley
Ecological impacts resulting from construction and operation of the
hypothetical solar-electric plant will be long termed and variable. These
impacts will involve distinct changes in the physical environment, vegetation,
and animal life now existing on the area. Each of these impacts will be dis-
cussed in appropriate sections.
Both the proposed and alternate solar-electric sites are areas with
similar topographic and biotic features, although the alternate site does ex-
hibit a more varied topographic diversity with a small northern portion of
approximately 2 to 4 km which would be unsuitable for plant construc-
tion. Also, the more northerrn portions of the alternate site were not a
part of the Harry Allen Station Study Area and were not studied. This north-
ern area appears, however, to be quite comparable. It has been documented
that biotic species diversity and abundance increase with elevation in the
northern Mojave Desert of southern Nevada (Ref. 4-1). Therefore, it is ex-
pected that the alternate site will exhibit greater species diversity; hence the
original site is more desirable for plant construction and operation. Either
site, however, would have similar environmental impacts differing only
slightly in degree of disruption of native biota. The following impacts will
apply to either the proposed or alternate solar-electric sites.
Terrestrial Impacts of Construction
Construction will involve the movement and use of varying kinds of
heavy equipment. Although this construction will occur in phases, it is
reasonable to assume that most of the 52 km square mile area will be
4-1
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significantly disturbed by equipment movement and/or construction. This
disturbance will include assorted activities, such as drilling, digging, filling,
leveling, and construction of roads, solar modules, and buildings. These
construction activities, in conjunction with movement of heavy equipment,
will cause drastic changes in soil surface and destroy much of the sparse
desert vegetation now existing on the area.
Soils--
Desert soils are commonly protected from wind and water erosion by
one of two surface layer features. In many areas, there is a layer of desert
pavement composed of small rocks fitted together to form a mosaic on the
soil surface. This layer has developed over long periods of time due to re-
moval of soil particles from the surface by wind and the settling of rocks
into position. Sometimes these rocks are cemented into place by chemical
precipitates of soil leaching. This forms a relatively stable surface which
may be largely devoid of any but perennial vegetation. This type of surface
is relatively resistant to damage and can withstand such activities as move-
ment of small vehicles and walking. This surface, however, would be greatly
altered by movement of heavy equipment and/or construction activities.
A soil crust composed of desert lichens, mosses, and chemical sedi-
mentation is a more common and widespread feature found throughout the
Mojave Desert. This crust varies in thickness and stability dependent upon
whether the basic chemical sedimentation is combined with soil lichens and
mosses. This crust, however, is extremely vulnerable and easily broken,
even by walking across the surface.
Areas not having these two surface features are overlain with soil par-
ticles which are unstable and easily eroded by wind and/or water. These
two soil features are extremely important in preventing erosion. In areas
where these soil surfaces have not been stabilized, erosion is a major eco-
logical force due to the activities of strong winds and short, but intense rain-
fall which may result in both sheet and gully erosion. After stable soil
surfaces are broken, they become unstable, and remain unstabilized and
vulnerable to further erosion for decades. For example, army maneuvers
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performed by tanks during World War II in the Mojave Desert of southern
California are still evident.
Vegetation--
Perennial vegetation in the low desert is very sparse with plant cover
ranging from approximately 1 to 5%. Therefore, disruption of the sparse
vegetative landscape does increase the intensity of erosion by wind and water.
Due to the fragile nature of the soil surface and sparse distribution of
vegetation, the varied activities during construction would greatly alter the
physical and vegetative landscape. This would result in severe erosion of
the soil surface. Possible mechanisms to promote soil stabilization will be
discussed under mitigative measures.
It is anticipated that much of the perennial vegetation present on the
plant site will be destroyed during construction activities. It is highly de-
sirable that extreme caution be used and construction practices be developed
which will allow minimal damage to existing perennial vegetation. Regulatory
attention may be required, together with management incentives at all levels
of supervision.
To the extent consistent with brush fire prevention, small areas of
existing vegetation should be maintained to promote revegetation following
construction. It must be recognized that revegetation (plant succession) is
very prolonged and highly variable in desert areas of low precipitation.
When Mojave Desert vegetation is destroyed, several decades, and in some
instances, more than a century, are required before natural or original plant
cover is re-established (Refs.4-2 and 4-3).
Desert environments present numerous difficulties for restoration once
vegetation has been partially or totally destroyed. Even when sufficient vege-
tation is left which provide seed reservoirs for re-establishment, revegeta-
tion is greatly prolonged. This is due not only to erosion of the soil surface
but establishment of invader species. Rainfall appears to be the dominant
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factor in revegetation success with above 25 cm of rainfall per year needed
for successful revegetation under natural conditions (Refs. 4-4, 4-5 and 4-6).
Rainfall on the construction sites is extremely variable from year to year,
ranging from approximately 2.5 to 13 cm (Ref. 4-1). Therefore, it is ex-
pected that vegetative recovery will be extremely slow on the construction
site unless mitigative measures are introduced.
Perennial vegetation over most of the construction site will be se-
verely damaged or destroyed during construction. This will result initially
in almost complete removal of perennial vegetation which provides almost
all plant cover occurring on the area. Annual species (small herbs) germi-
nate in winter and early spring and flower and develop fruit in spring and
early summer. Species composition and density varies greatly from year to
year dependent upon late winter and spring rainfall (Refs. 4-7 and 4-8). Plant
cover for annuals in the low Majave Desert and of southern Nevada usually
ranges from 0.3 to 3.0% (Bradley, unpublished data). After initial removal
of much of the perennial vegetation, desert annuals should increase greatly
in density. This is due not only to decreased competition "with perennials
for available water but also to disturbance of the soil surface which provides
a more ideal environment for germination of annual seeds. This increased
density of annuals, however, will provide only minimal stabilization of the
soil surface due to only seasonal occurrence on the area.
Along with the increased density of annuals, there will be appreciable
development of non-native invader species, comprised mostly of annuals.
Important non-native species which may achieve high densities and biomass
on the area will include Russian Thistle (Salsola spp), grasses (Bromus
rubens and B. tectorum), and Storkbill (Erodium cicutarium). Within a few
years after initial disturbance, these invaders will provide more plant cover
than native, annual vegetation. The extent to which this growth would cause
an intolerable fire hazard has not been investigated. Indeed, it is not clear
that grass fires would damage modules, PCM's or battery houses if clear
zones about these are maintained.
4-4
-------
Vegetative succession after the initial invasion of annuals is varied
especially in terms of time, but usually relatively simple in terms of species
composition. At some undetermined time, perennials such as Desert Mari-
gold (Baileya spp.) Cheese-weed (Hymenoclea salsola), Matchweed (Gutier-
rezia spp.) and Desert Mallow (Sphaeraclea ambigua) will become established.
These species, while present in Creosote Bush Communities, more commonly
occur along desert washes or other disturbed areas. Further serai stages
leading to the climax Cresote Bush Community have not been adequately de-
scribed, and both their species composition and temporal duration are
unknown. Plant succession leading to the climax community, although in-
adequately described, may exceed 100 years in duration. Because the solar
array will cause shading about each module (cf. Section 4.2), revegetation
will never be re-established with identical geographic distribution of species.
Vertebrates--
Disruption of the soil and native vegetation by construction activities
will result in highly varied but significant changes to the vertebrate fauna
presently occupying the solar-electric sites. During phases of construction
much of the habitat requirements of individual species, such as food, shelter,
and resting sites, will be removed. This will result in drastic reduction in
individual populations due to increased mortality and dispersal from the
construction area. Modification in population levels will vary greatly be-
tween species largely dependent upon home range size, range of normal
movement, shelter and food requirements, and habitat specificity. It must
be realized that vertebrate populations may be largely interrelated through
food webs and other biotic relationships and decrease in population of an
individual species may affect population levels of other species.
As far as an individual species is concerned, several possibilities
exist after drastic alterations of habitat by construction activities. If the
species is not habitat - specific or utilizes the area only for a portion of its
life requirements, population levels may remain similar to those before
construction. An example would be the various species of bats which utilize
lower desert Creosote Bush Communities primarily for foraging activities.
4-5
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Their food supply, largely made up of volant insets, would still remain on the
site, although perhaps in reduced densities, and occupy areas of similar
habitat. Bats have high mobility and forage over large areas; hence, popu-
lation number and species composition of the lower desert bat fauna would
not be significantly altered by alteration of the landscape in the plant.
Larger carnivores such as the Coyote (Canis latrans), Gray Fox (Uro-
cyon cinereoargenteus), Kit Fox (Vulpes macrotis), and Bobcat (Lynx rufus)
range widely, are not habitat specific, and would primarily move into adjacent
areas of Creosote Bush Community in response to diminished food supply
(rodents and rabbits) and disturbance due to construction activity. Current
plans call for the plant to be surrounded by a perimeter fence to exclude
large animals and trespassers. This fence would make it difficult for the
larger carnivores to disperse back onto the sites if and when population levels
of prey species became adequate to sustain predator populations. It is pos-
sible that some may burrow under the fence. It is also possible that some
deliberate effort may be required in order to re-establish these predator
species, especially if rodent and rabbit populations become a problem. Such
efforts might include construction of small gaps in the perimeter fence.
Another possibility is live trapping and relocation with the cooperation of
appropriate Federal and Nevada wildlife managers. As compared to the
previously mentioned carnivores, Badgers (Taxidea taxus) have reduced
mobility and are directly dependent upon burrowing rodents as a food source.
Hence, their presence, absence, or depleted population levels within the plant
would be directly related to burrow rodent populations, as well as the extent
to which the fence prevented their re-establishment. The Skunk (Spilogale
putorius) is a small carnivore not commonly found in Creosote Bush Com-
munity except along major desert riparian environments and mesic habitats.
The only large ungulate reported for the general area of the construc-
tion sites is the Desert Bighorm Sheep (Ovis canadensis nelsoni). This species
is present throughout much of the higher elevations of the Arrow Canyon Range
which is adjacent to the plant sites. Some movement does occur across low
elevation desert to the Sheep Range situated across the valley to the west of
Arrow Canyon Range. Sheep, however, do not normally move into low desert
. • . 4-6
-------
east of Arrow Canyon Range where construction sites are located. Hence,
they would have occurred on the construction site only rarely. Therefore,
normal movements would not be impaired by construction activities or
perimeter fencing.
A majority of the 70 species of birds found in the vicinity of the con-
struction site are transients (migratory), visitants, or seasonal residents.
Bird distribution, especially in relation to species diversity, is closely re-
lated to the heterogeneity present in the vegetative landscape which provides
shelter and resting sites (Ref. 4-9). Due to their wide ranging foraging activ-
ity, local food supply is of secondary importance for both density and species
diversity. Therefore, after initial removal of much of the vegetative land-
scape, which provides habitat, both population levels and species diversity
would be greatly curtailed on the solar-electric site. Birds normally utilizing
the area would then occupy adjacent areas of similar habitat which are wide-
spread and continuous. Birds would begin to use the construction site to
varying degrees as vegetation became re-established.
Small mammals, such as rabbits and rodents, have reduced home ranges
and their long-termed presence on the construction sites would largely be de-
pendent upon the extent of vegetative recovery. During construction, not only
would their food supply be drastically reduced by removal of browse, but much
of the seed reserves located at or near the soil surface would be covered over.
Also a majority of the rodent burrows would be destroyed as well as vegetative
shelter for rabbits. These losses in food supply and shelter would greatly
disrupt normal activity patterns resulting in high mortality and dispersal
from the construction areas. Only a sparse population of rodents and rabbits
would be expected to survive on the solar-electric sites upon termination of
construction. Initial establishment of invader plant species and eventual
native annual plant production would provide an abundant food source for both
rodents and rabbits. Rabbits especially would be expected to develop high
densities adjacent to construction sites and utilize heavily the abundant green,
succulent forage found on the edge of solar-electric sites. Reestablishment
of residency on the plant site, however, would depend upon sufficient recovery
of perennial vegetation to provide an adequate distribution of shelter and shade
4-7
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sites throughout the area. In contrast, however, the disturbed soil surface
following construction would provide an ideal environment for the establish-
ment of new burrows by rodents. Species composition and densities of the
rodent fauna returning to the solar-electric sites would be different from
those previously found under undisturbed conditions. Species believed to re-
establish themselves at high densities on areas of the low desert are Merriam's
Kangaroo Rat (Dipodomys merriami) and Antelope Ground Squirrel (Ammo-
spermophilus leucurus), which are both characteristic of the Creosote Bush
Community (Refs.4-10 and 4-11). Continued changes in rodent densities and
species composition would be expected during the various phases of vegeta-
tive recovery.
Reptiles are another major group of vertebrates of limited mobility with
many species having reduced home ranges. Snakes have relatively large home
ranges for reptiles, as they forage widely for prey species primarily com-
posed of rodents of rodents and lizards (Refs.4-12 and 4-13). Species com-
position and densities are largely related to food supply, and dispersal should
occur from the construction sites due both to depletion of food resources and
destruction of shelter and hibernals. Reestablishment on the areas of a char-
acteristic snake fauna would coincide with vegetative recovery and population
densities of prey species.
The Desert Tortoise (Gopherus agassizi) is herbivorous and forages
widely on a variety of desert plants. Each individual uses a large number of
burrows both for daily shelter and for hibernation. Construction activities
would not only remove most of the forage, but also destroy the majority of
burrows, sometimes during occupancy. Unless mitigative measures are
introduced, construction would result in high mortality, especially if con-
struction occurs during periods of hibernation. Surviving Desert Tortoises
would disperse into adjacent areas surrounding the solar-electric sites where
hopefully they could find abandoned burrows or construct new ones. Re-
establishment of viable Desert Tortoise populations on the solar-electric
sites would occur only if vegetative recovery approaches natural conditions.
Lizards have the most restricted movements and smallest home ranges
of any reptiles found in the area and are largely dependent upon perennial
4-8
-------
vegetation and abandoned rodent burrows for shelter and hibernal sites
(Refs. 4-14 and 4-15). Heavy mortality involving destruction of shelter is to
be expected during construction, particularly during winter months when
practically all species are hibernating. Reestablishment of the character-
istic lizard fauna on the solar-electric sites would occur only after estab-
lishment of rodent burrows and perennial vegetation for shelter.
Aquatic Impacts of Construction
The proposed solar-electric sites lie immediately adjacent to the
drainage into Dry Lake playa. The central portion of the playa becomes a
temporary lake for varying periods of time only after high intensity rainfall
occurs in the surrounding area. An appreciable body of water (lasting over
an extended period of months) is present in years of high rainfall, occurring
at irregular intervals. The playa may remain essentially dry for periods of
several years. Construction activities, especially leveling, road building,
and placement of solar modules may disrupt patterns of existing drainage on
to the playa. If heavy rainfall occurs during construction or before some
soil settling and stabilization have occurred, erosion may be a major factor
on the .area. Also the sediment load from drainage onto the playa would be
increased due to the erosion of loose soil. Disruptions of natural drainage
by construction would have little permanent effect since new drainage channels
would become established over a period of years resulting in normal drainage
to the playa.
The ephemeral, aquatic fauna found on the playa is restricted largely
to crustaceans which form resistant eggs that can withstand desiccation for
several years. Adult forms are only found during periods of temporary
water. The total amount of water discharge on to the playa would be little
affected by plant construction, and the initial increase in sediments would
have little effect on the aquatic fauna since it is adapted to highly turbid
levels.
4-9
-------
Terrestrial Impacts of Operation
The ecological consequences of continued plant operations are minimal
when compared to the drastic alteration of soil surface, vegetation, and animal
life resulting from construction activities.
The period of plant operation will involve only minimal disruption of
the area due to use of roads for inspection and maintenance. Any major re-
pair of existing modules or other installations involving the use of heavy
equipment would further alter the soil surface, vegetation and habitat of
animals. Major repairs, however, are expected to be minimal, and routine
inspection should result in little further or continued damage to the environ-
ment.
Both wind and water erosion will be greatly accelerated during early
phases of plant operation due to the removal of perennial vegetation, soil
crust, and desert pavement. Before soil stabilization the effects of water
erosion upon the plant site are highly unpredictable due to highly variable
yearly precipitation patterns. If high intensity rains occur, they may well
produce, gullying to the extent of undermining solar modules and/or causing
road damage. The effects of water erosion will diminish with time with the
reestablishment of perennial vegetation and soil stabilization. Wind erosional
effects will also be pronounced during the early phases of plant operation be-
fore stabilization of soil and vegetation. To some extent, the placement of
modules may disrupt wind patterns, modifying their intensity. It is expected,
however, that wind blown soil will accumulate around the leeward base of
modules, and if sufficient accumulation occurs, this soil may interfere with
their movement. Wind erosion will diminish as soil surface and vegetation
become reestablished. Deliberate introduction of selected plant species to
reduce soil movement is a possibility which we have not investigated.
Placement of solar modules would result in greatly increased shading
over an appreciable amount of the solar-electric site. Shading patterns would
be highly variable, dependent upon time of day and season, with areas directly
under modules in permanent shade. The major effect of this greatly increased
4-10
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shading would be decreased evaporation of water from the soil surface and
reduced transpiration from existing vegetation. Additionally, rainfall spashed
from modules would fall in the area outside of the foundation ring! thereby
providing a mesic boundary around the rotating portion of each module. This
area would be ideally suited for revegetation of both annual and perennial
plant species due to increased water availability. Initial vegetative estab-
lishment would be of typical invader or weed species, such as brome grasses
and Russian Thistle. The sequence of serai stages in these shaded areas is
unknown and to what extent they might involve species not characteristic of
Creosote Bush Communities is probably dependent on seed dispersal. The
most probable successional sequence is an accelerated reestablishment of
characteristic vegetation which would grow more rapidly and achieve larger
individual plant size than on the non-shaded portions of the plant site.
The placement of modules over a large area will provide little inter-
ference with development of vegetation and reestablishment of character-
istic small vertebrate populations in the area between and adjacent to solar
modules. The mesic boundary immediately adjacent to the module should
provide ideal habitat for arthropod populations and abundant seed and browse
for forage by rodents and rabbits. Crevices at the base of each module will
provide additional habitat for arthropods, lizards, snakes, and perhaps small
mammals. The shaded portions of the modular support structure may pro-
vide nesting sites for breeding birds as well as roosting sites for some species
of bats. If sufficient recovery of vegetation is achieved, the placement of
modules can be considered as a means of increasing the environmental heter-
ogeneity of the Creosote Bush Community, possibly resulting in a more varied
biota than under natural conditions.
However, the reestablishment of small vertebrates will have to be
monitored in the module groups which are installed first. Possibly burrow-
ing animals and nesting birds could interfere with module performance.
*Most rain striking the modules will drain into gutters and be directed onto
crushed rock pads within the foundation ring.
4-11
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The probable reestablishment of vegetative and animal life for non-
shaded areas has been described in the section, Terrestrial Impacts of Con-
struction. It is emphasized that routine inspection and maintenance would
not appreciably alter these natural processes.
Off site Aquatic Impacts of Operation
Ecological impact due to drainage from the construction sites into Dry
Lake playa, the only aquatic environment present adjacent to the study area,
has been discussed under the section, Aquatic Impacts of Construction.
Following construction, any obstructions to previous drainage patterns onto
the playa from the solar-electric sites will be overcome by the development
of new and adequate drainage. No long lasting, detrimental effects are ex-
pected on the ephemeral fauna of Dry Lake playa due to plant operation.
Absence of Thermal Pollution Effects
Ecological impact due to thermal discharge will be essentially non-
existent. Total heat rejection (from discharging and charging) is relatively
low and will be spread over the entire site. In comparison to the heat dissi-
pated by an equivalent coal-fired plant, solar-electric modules release ap-
proximately 90% less heat to the surrounding environment. It is highly
unlikely that the vegetation, soil, or animal life will be adversely affected
by the relatively low thermal discharge of the solar-electric plant.
Conclusions
The major ecological impact will be terrestrial on the solar-electric
sites, whereas aquatic impacts will be minimal. Additionally, the most pro-
nounced alteration of environment will occur during construction phases when
much of the protective soil layer will be destroyed and much of the perennial
vegetation removed. Although construction methods should be used that pro-
vide minimal destruction, it is recognized that soil surface and vegetation
changes will be a major impact upon the area and will be of extremely long-
term duration. The removal of surface crust and vegetation during construc-
tion will be accompanied by destruction of shelter and reduction of food
4-12
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resources for much of the animal life on the area. High mortality and dis-
persal from the area by wildlife is to be expected.
Following the massive alteration of habitat on the solar-electric sites
during construction, the effect of plant operation will be minimal or virtually
nonexistent and will allow for extremely slow recovery of the environment
through revegetation and soil stabilization, accompanied by the reestablish-
ment of a characteristic desert fauna. Recovery of the environment to a
near natural condition, however, is expected to take an extremely long period
(approximately 100 years). The successional stages of vegetative recovery
may be greatly enhanced by mitigative measures.
No plant species on the proposed or alternative solar-electric sites
may be considered rare or endangered. Two animal species, Desert Tortoise
and Kit Fox, are either on the threatened or protected state list of Nevada.
Desert Tortoises (on the threatened list) are common on the solar-electric
sites and heavy mortality is expected during construction, especially during
fall, winter, and early spring months when hibernation occurs. The Kit Fox
(on the protected list) is becoming uncommon to rare near cities or other
developed areas in the Mojave Desert. It is, however, still a common car-
nivore over much of the low desert "where its habitat has not been altered.
It is common on both the proposed and alternate plant sites and would be ex-
pected to disperse from the site during and following construction as its food
supply (rabbits and rodents) decrease. A wide expanse of suitable habitat is
found adjacent to the solar-electric sites.
4.2 SHADING BY SOLAR MODULES
Depending on the time of year, each of the 50,000 identical modules'
shadows will sweep out identical paths across the adjacent ground determined
by the modules' dimensions and the sun's apparent trajectory. Some repre-
sentative shadows and the loci of shadow extrema are depicted schematically
in Figures 4-1, 4-Z and 4-3 for the summer and winter solstices and spring
4-13
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N
I 1
20 ft.
(6.1 m)
K
Sunrise @ 62
Sunset @ 298
/ Summer Solstice, 34 N Lat.
Spectrolab/Ingenasu Module
Central 76.3 cm circle is always shaded. Remainder,
within loci of extreme shade margins, is shaded at
some time during the day. Representative shadows
are shown.
Figure 4-1. Module shadows and loci of shadow extrema for summer solstice.
-------
M
Ul
Winter Solstice, 34 N latitude
Spectrolab/Ingenasu module.
Central 76.3 cm diameter circle
is always shaded. Remainder
is shaded at some time during
day; boundaries are loci of
extreme shade margins.
Representative shadows shown.
Figure 4-2. Module shadows and loci of shadow extrema for winter solstice.
-------
N
I 1
20 ft.
(6.1 m)
i
H1
cr\
Spring and fall equinoxes (~3/21 and 9/21), 34 N
latitude. Spectrolab/Ingenasu module. Central
76.3 cm circle is always shaded. Remainder, within
indicated loci of extreme shade boundaries, is
shaded during some portion of day. Representative
shadows are shown.
Figure 4-3. Module shadows and loci of shadow extrema for spring and fall equinoxes.
-------
*
and fall equinoxes. Because the modules rotate about only a vertical axis
so as to track the sun, but do not alter their inclination, the shadow loci are
not determined simply. In Table 4-1 we present the numerical data from
which Figures 4-1, 4-2 and 4-3 were constructed, in part. The effects of
this shadowing include:
a. Primary ecological effects related to species' preference for
shadow or sunlight
b. Effective "mulching" by the solar array which, in effect plays
the role of a synthetic boulder field
c. Increased moisture retention (reduced evaporation) and reduction
in soil heat due to (b)
d. Secondary ecological effects arising from (c) above
e. Secondary ecological effects related to defensive cover (conceal-
ment) afforded by module shadows.
None of these effects is presently quantifiable. The "mulching" and conse-
quent increased moisture retention and reduced soil heat are capable of
modeling or experimental determination, but this has not been done. The
land surface will be altered by construction. The altered surface must be
used in any modeling or experimental program; because of erosion and vege-
tation changes, this surface will itself be changing. Further aspects of
shadowing are discussed in Sections 4.1 and 5.7.
As reported in Section 2.5, the 2 to 3 in. deep vesicular layer on the
soil surface greatly reduces downward heat transport and dissipation; this
creates a major obstacle to establishment of any but the most heat resistant
seedlings. Shadowing will reduce soil heat. This, coupled with some slight
increase in moisture due to rainfall splash from modules will encourage re-
vegetation. This is discussed in Section 4.1. At present 80% of the species
occurring naturally are found only on stony situations (Ref. 4-16) which this
array may approximate.
*
These figures were developed for 34°N latitude (the actual plant site runs
from 36°23' to 36°35" N latitude, approximately) for which astronomical
data were in most convenient form. For small latitude changes, small
changes occur in the shadow loci. The north-south components of cell
shadows is longer at higher latitude, for example.
4-17
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TABLE 4-1. SHADOW LENGTHS FOR 10.4 HIGH
STRUCTURE AT 34°N LATITUDE
Sun Azimuth,
deg
Summer Solstice
62
90
135
180
225
270
298
Sun Altitude,
deg
0
45
76
80
76
45
0
Shadow, I,
m
00
10.4
2.6
1.8
2.6
10.4
oO
Time of
Day
Sunrise
Noon
Sunset
Spring and Fall Equinoxes
90
135
180
225
270
Winter Solstice
120
135
180
225
240
0
47
56
47
0
0
16
32
16
0
OO
9.7
7.0
9.7
OO
00
36.2
16.6
36.2
00
Sunrise
Noon
Sunset
Sunrise
Noon
Sunset
4.3 THERMAL POLLUTION
As described in Section 1.2, a charge-discharge cycle for the batteries
involves a 20% loss. With three hours storage capacity, this is 240 MWhr
(8%) waste heat released to the environment during charging, and 360 MWhr
(12%) during discharge. Discharge is likely to occur more frequently at its
maximum rate, 120 MW, than is charging. Charging may be done in incre-
ments during late p.m. and early a.m.
4-18
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By comparison, a moderately inefficient 1000 MW coal-fired plant would
reject waste heat at the rate of almost 2000 MW. Normalizing both plants to
eight hours generation, a fossil fuel plant rejects nearly 27 times more heat
than does a photovoltaic solar plant. Additionally, the heat rejection by con-
ventional power plants is concentrated at cooling towers and/or in thermal
plumes in natural surface waters. This solar plant's waste heat release is
spread over 52 km . This corresponds to perhaps a hundredfold reduction
in the areal intensity of the effect.
Further small quantities of waste heat are rejected by the silicon ab-
sorbers, which run at a steady state temperature of —100 C. This, however, is
energy which would have been reradiated in part by soil were there no solar
plant. The overall efficiency of this solar plant corresponds to an albedo within
the normal range of soil types: 15% loss as visible radiation at the primary and
secondary reflectors, and another 68% partly (perhaps mostly) as heat at the
absorber. The total, 83%, is spread over an areal receiver density of about
16%, and is in addition to the heat radiated by the uncovered 84% of the land
area. Assuming all unutilized light is emitted as infrared radiation or lost
convectively the heat budget is therefore ~83% rejection over 16% of land area
plus bare earth albedo loss over 84% of the land area. Averaged over the entire
array field (modules plus soil), the net effective albedo loss, a, would be
a = 0.84 x bare earth albedo loss + 0.16 x 0.83
Bare earth albedo losses range from 0.70 to 0.97. Taking ~0.85, we have
a ~0.84, well within that range.
4.4 VISUAL EFFECTS
This installation extends from U.S. Interstate 15 almost to the Arrow
Canyon Range to the west. Each module is about the size of a small house.
Center-to-center spacing on the square grid is 33 m. In every 10 x 10 group
of modules, there are two low block buildings containing batteries and power
conditioning equipment.
We can envision the visual effect as that of a city of 50,000 small homes
arrayed over a perfectly uniform square block pattern on flat terrain. There
is no way to hide such a scene, at its proposed hypothetical location.
4-19
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Lovers of the openness and wildness of the undisturbed desert may
be displeased. Nevertheless, we expect this installation to be,for a time,
a tourist attraction for those people who visit works of man such as
Hoover Dam. Moreover, there do not appear to be any productive
alternative uses for this land which would not cause greater potential
scenic deterioration. Nevertheless, aesthetic acceptance of this plant
is subjective and therefore subject to great variations in individual
acceptance.
4.5 ATMOSPHERIC EMISSIONS
Other than thermal emissions, discussed in Section 4.3, the follow-
ing potential sources are identified:
• Battery houses, in the event of fire. Emissions could
include Li2O or LiOH, A^2O3, SOX, and other com-
bustion products. Cell constructions seems to make
fire a very improbable event. Modular construction
limits a fire to a small unit.
• Degraded plastic and adhesive in primary collectors.
Both photolytic and thermal decomposition are
possibilities which must be considered (cf. Section L2).
Without additional information on plastics and adhesive
composition, we can only suggest that emissions may
include unsaturated hydrocarbons, halogenated organics,
organic acids, alcohols, and other oxidized species.
Identification of emissions and transport modeling for
this distributed source would have to precede an evalu-
ation of occupational hygiene effects, public health
effects, and ecological effects. It seems very unlikely
that any reflector material, whose use is economically
justifiable would suffer rapid enough/degradation to
create an air pollution problem (cf,, Section 1.2);
o Diesel generators. These would be used during
construction, particularly for welding, and for
emergency plant power. Exhaust emissions can
include CO, NOx, hydrocarbons, particulates,
aldehydes, organic acids, and SOX. These can be
quantified if the number and size and characteristics of
such generators is defined. These are expected to
be a minimal, indeed negligible air pollutant source,
even during construction.
4-20
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Fugitive dust during land preparation and construction.
We identify this as the only signficant air pollution
problem associated with the project. It does not
differ in kind, or extent from that observed in large
highway construction projects, for example. Although
economically unattractive, there exist hygroscopic
dust suppressants and chemical binding agents. We
do not believe their use is either necessary or justi-
fiable during construction. Further, they introduce
a foreign substance capable of being transported by
run-off waters.
Vehicular emissions during construction.
Fugitive emissions from quarrying, cement manu-
facture, and concrete batching. About 10° m^
of concrete, on an average of 1CP m^/yr must be
batched and transported to construction sites. Nearly
10 MT of steel must also be transported. We
anticipate that much of the steel will be delivered by
rail. Concrete may be batched on-site. Analysis of
these pollutant sources more properly awaits resolution
of the vast logistical problems arising from this
project.
In addition, about 1000 workers will be commuting
from the Las Vegas vicinity daily, adding to the
vehicular burden.
As compared with conventional generating stations, the following
air pollution effects will be absent:
• Combustion products
• Drift and fog from cooling towers
• Breeze (airborne dust) from coal piles and radiochemical
discharges from nuclear reactors.
Absence of appreciable air pollution, together with complete freedom from
process water requirements, constitute the two most important direct en-
vironmental advantages of solar-photovoltaic power generation.
4.6 EROSION
Both wind and water erosion will be affected. Surface wind velocities
will be. reduced substantially (Ref.4-17) because of increased "roughness."
Therefore, this project would seem to have a beneficial effect on wind
4-21
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erosion after vegetation is reestablished and surface soil consolidation
has occurred. Both processes, however, are very slow in the desert en-
vironment. We have no estimate at hand on the severity of the wind
erosion problem. A substantial body of experience surely exists among
major Southwestern engineering construction and agricultural engineering
firms. This experience seems likely to be more useful than experiments
or simulation, and should be drawn upon.
Water erosion is unlikely to be severe. The terrain is level and the
soil permeable. Natural drainages will be maintained undisturbed to the
maximum extent possible. Hard rains seldom occur (cf. Section 2.6,
Figure Z -3).
4.7 WATER QUALITY AND SUPPLY
No appreciable effect upon groundwaters has been identified which
fails to meet public health standards. In practical terms, there is no sur-
face water at, or near, the site.
A source of construction water has not been identified. Such water
will have to trucked to the site after purchase by the concrete batch plant
subcontractors and is subject to permits, appropriations, etc.
4.8 LAND USE
This matter is discussed in Sections Z, 3, 6 and 8. The land has no
present or forseeable productive use in the absence of the project. There-
fore, the proposed action constitutes a beneficial conversion of waste-
land to productivity.
4.9 NOISE
As distinct from turbogenerator installations, there is no large high
speed rotating equipment.
4-22
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Module drive motors will be small low horsepower ac motors
(probably about 1 hp) driving high reduction ratio gear boxes. No notice-
able motor noise is anticipated at the perimeter fence. Other noises
(60 cycle hum, maintenance vehicles) are considered minor and com-
pletely overwhelmed by highway traffic and military jet noises.
4.10 WASTE DISPOSAL
This installation generates no process waste streams. Sanitation
wastes during construction are hauled away and during operation are
given secondary treatment by small package plants.
4.11 TRANSMISSION LINES
No new transmission lines are planned. Existing lines in the existing
corridor adjacent to the plant will be used.
4.12 EFFECTS ON LOCAL HISTORIC OR CULTURAL AMENITIES
None. (cf. Section 2.10).
4.13 EFFECTS ON LOCAL AND REGIONAL DEMOGRAPHIC, SOCIO-
ECONOMIC, AND COMMUNITY CHARACTERISTICS
Population Effects
A maximum construction work force of approximately 1000 crafts-
men and supervisors is anticipated. This level would be maintained for
about 7 to 8 years of the projected 10-year project.
Clark County Regional Planning Council Projections for population
growth envision a flat rate growth of 16,200 i ? 600 ^er year in t^ie Perio<*
1977-2000. Even including dependents, the population effect of this pro-
ject will be trivial. In as much as "alternative" power plants would be
required were this hypothetical plant not "built," it seems that the popu-
lation effects do not merit attention.
4-23
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Municipal Services
The environment surrounding the proposed plant is both fragile
and inhospitable. There are now in existence no communities near
the site. We propose to actively discourage any development of con-
struction villages. By providing bus service from Las Vegas, by firm
persuasive efforts with contractors and subcontractors, and by any other
exhortations at our disposal, we will attempt to dispose the entire work
force to settle in the Las Vegas urban area primarily, and Henderson
and Moapa Valley communities secondarily. The latter have suffered
declining populations recently, and only Overton (pop. ~1300) can absorb
an appreciable influx.
Because the projected Clark County population increase is expected
to overwhelm the plant construction crew contribution, we anticipate no
area-wide problems with municipal services. This would include water,
sewerage, hospitals, schools, etc. Consult Section 2.2 for tabulations
of presently available and projected facilities.
Although area-wide problems are not expected, it is probable that
local shortfalls will occur. This is particularly true in Moapa Valley
towns and school districts and small communities in the Las Vegas urban
a rea0
Manpower
Table 2.2 and 2.3, Section 2.2, present data relative to the size and
characteristics of the locally available labor force. The atypically small
percentage of craftsmen, especially cement masons, electricians, line-
men, ironworkers, and operating engineers, suggests that an infusion of
craftsmen into the economy is an almost certain consequence of this
hypothetical project. Typically these craftsmen will have higher wages
than service industry personnel. Consult Section 2.2 and Ref.4-18.
4-24
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Infusion of Capital
n
Much of the $1.67 x 10 capital investment for this plant will be
spent at distant locations where collectors, absorbers, and superstructures
and power conditioning equipment are fabricated. We estimate that less
than $300 M (including $220 M contingency) could be spent locally in a
normal community. The absence of a substantial local manufacturing
industry suggests that the project will have smaller financial impact. De-
tailed analysis is possible, but outside the scope of this task.
4.14 REFERENCES
4-1. Bradley, W0 G., and J. E. Deacon. The Biotic Communities of
Southern Nevada. Nevada State Museum Anthro. Papers, 13(4):
201-295, 1967.
4-2. Wallace, A., and E. M. Romney. Radioecology and Ecophysiology
of Desert Plants at the Nevada Test Site. ERDA Report TID-
25954, 1972.
4-3. Wells, P. V. Succession in Sert Vegetation on Streets of a
Nevada Ghost Town. Science, 1 34:670-671, 1961.
4-4. Hull, A. E. Jr., and R. C_ Holmgren. Seeding Southern Idaho
Rangelands. INT-10, U.S. Forest Service Research Paper,
1964. 31 p.
4-5. Plummer, A. P., D. R. Christenson, and S. B. Monsen.
Restoring Big-Gam Range in Utah, Publication No. 68-3,
Utah Division of Fish and Game, 1968,
4-6, Tueller, P. T., A. D. Bruner, and J. V. Davis. Ecology of
Hot Creek Valley-Vegetation-and Soil Response to Underground
< Detonation. ERDA Report NVO-409-1, 1972.
4-7. Beatley, Jc C. Survival of Winter Annuals in the Northern
Mohave Desert. Ecology, 48:745-750, 1967,,
4-8. Beatley, J. C. Biomass of Desert Winter Annual Populations
in Southern Nevada. Oikos, 20:261-273, 1969.
4-9. Miller, J. S. The Avian Community Structure of Las Vegas
Wash, Clark County, Nevada. M. S. Thesis, University of
Nevada, Las Vegas, Las Vegas, Nevada, 1974. 239 pp.
4-10. Beatley, J. C. Environments of Kangaroo Rats (Dipodomys)
and Effects of Environmental Change on Populations in
Southern Nevada. J. Mamm., 57:67-93, 1976.
4-11. Bradley, W. G., and R. A0 Mauer. Rodents of a Creosote
Bush Community in Southern Nevada. Southwest Nat.,
17:333-344, 1973.
4-25
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4-12. Clark, R. E. The Feeding Habits of Snakes of Southern
Nevada. M. S. Thesis, University of Nevada, Las Vegas,
Las Vegas, Nevada, 1968. 89 pp.
4-13. Stebbans, R. C. Amphibians and Reptiles of Western North
America. McGraw-Hill, New York, 1954. 528pp.
4-14. Mahew, W. W. Biology of Desert Amphibians and Reptiles.
In: Desert Biology, G. W. Brown, ed. Academic Press,
New York, 1968. pp. 195-356.
4-15. Stebbans, R. C. Amphibians and Reptiles of Western North
America. McGraw-Hill, New York, 1954. 528 pp.
4-16. Lloyd Rooke, Soil Conservation Service, USDA, Las Vegas,
Nevada. Private Communication with D. Richard Sears,
Lockheed -Huntsville, June 1976.
4-17. Sears, D. Richard, and P. O. McCormick. Preliminary
Environmental Assessment of Solar Energy Systems. IERL-
Ci-101 (also LMSC-HREC TR D496748), Lockheed-Huntsville
Research & Engineering Center, Huntsville, Alabama,
February 1976.
4-18. Nevada Power Company. Environmental Assessment, Allen-
Warner Valley Energy System, Vol. Ill, Harry Allen Station,
September 1975, and Appendices Volume to Vol. III. September
1975, Las Vegas, Nevada.
4-26
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SECTION 5
ALTERNATIVES TO THE PROPOSED ACTION
5.1 GENERAL
The proposed facility is a hypothetical utility-size solar electric plant
utilized solely to assess its potential environmental impact. The primary
criteria used in selecting the plant site were that it be typical of a site likely
to be used for the first large (utility size) solar electric plant and a baseline
environmental study be in existence for the site. A site northeast of Las
Vegas, Nevada, was chosen because it satisfied these criteria.
We reemphasize here, as elsewhere, that this environmental impact
statement (EIS) is for a hypothetical plant. The specific area was selected
because Nevada Power Company has an active proposal and plans to con-
struct a 2000 MW coal fired steam electric plant at this site. In prepara-
&
tion for the project, Nevada Power and its contractors and consultants
prepared an extensive environmental assessment (Ref. 5-1) that contains
nearly all the baseline data needed for this EIS. We make extensive use of
Nevada Power's baseline studies by their permission and by permission of
the Bureau of Land Management.
The status of construction plans for the coal fired plant (the "Harry
Allen Station" ) is not affected by this report.
The design concept, described previously in Section 1, represents a
conceptual blend considered typical of a future large photovoltaic power
plant. The dssign features and characteristics are largely based on
presently available design studies conducted by and for Spectrolab, Inc.
5-1
-------
5.2 NO ACTION
This alternative is not consistent with established U.S. national goals
of achieving energy independence. These goals require development of new
sources of energy to augment present sources. Projected growth patterns
in the U.S. Southwest support the need for additional generating capacity.
5.3 FEASIBILITY OF LARGE POWER IMPORT
Treatment of this alternative is not within the scope of the present
effort.
5.4 REACTIVATION OR UPGRADING OLDER PLANTS
Treatment of this alternative is not within the scope of the present
effort.
5.5 ALTERNATIVE SITES
The characteristics of a solar-electric plant are sufficiently different
from the conventional coal fired steam electric and nuclear power plant to
bias strongly the choice of sites for the plant. Land use and amount of inso-
lation are prime factors to be considered. Collector area required for a
utility size plant is measured in thousands of hectares. The terrain should be
such that the slope maximizes the insolation and minimizes shading of the
collectors to maximize daily operation. A gentle uniform slope to the south
would be ideal. Plant sites located in hilly or mountainous terrain can
shorten the daily exposure of the collectors. Because of the large land area
required, the increased land preparation costs in hilly terrain prohibits its
consideration in the foreseeable future.
The large land area required for the solar-electric plant will necessi-
tate some type of access system to each solar module for routine mainte-
nance and servicing. Access can be either by road or some type of rail
system. In either event the road bed will have to support heavy equipment
for servicing the large solar modules which will weigh about 12.7 MT. The
5-2
-------
road access system is greatly simplified if the planform is rectangular and
compactness is maintained. If the terrain necessitates irregular planforms
or separates various modules by hills, the access system and transmission
lines to the main switchyard will be more complicated.
A solar electric facility which provides power for a network should be
considered relative to the main transmission lines within the network.
Transmission losses are minimized if the facility is located as near as pos-
sible to the main lines. The same holds for a facility which services a par-
ticular load center.
An obvious environmental consequence will be land use and modifica-
tion to the local ecosystems. The first solar-electric plants will probably
be located in the Southwestern United States. Much of this region is arid
desert where land use relative to population density is not the problem it
could be along the eastern seaboard, for instance. Considerable shading of
the terrain surface by the collectors can be expected. This may result in
the appearance of plants which live in shaded regions of the desert and pos-
sibly animal species new to the area. The main point is that the solar -
electric facility can be expected to change the local surface features.
Consequently, if the site is located near to or adjacent to parks, wildlife
preserves, etc., the scenic aspects should also be considered in the selection
process. References 5-2, 5-3 and 5-4 provide further useful information on
siting.
In summary, there are many candidate sites in the Southwest which
appear to meet the general criteria for a large photovoltaic power plant.
The site for this particular hypothetical power plant was chosen largely be-
cause of the availability of data pertaining to the particular area.
5.6 ALTERNATIVE SOURCES OF POWER GENERATION
General
Several alternative sources of power generation can be used for the
Southwest. -Among these are: (1) coal fired steam electric; (2) nuclear;
5-3
-------
(3) hydroelectric; and (4) advanced methods other than solar. Each of these
will be discussed in the following sections.
Coal Fired-Steam Electric
Among the conventional sources of power generation the use of coal is
the most viable means for this region. Coal is available in quantity from
nearby regions and can be transported to the facility via slurry pipeline,
truck or rail. The slurry pipeline is gaining industry acceptance as a means
of transport. However, for the Southwest this requires water, which is re-
latively scarce.
The principal limitation of a coal fired-steam electric plant important
in the Southwest is the scarcity of cooling water. Design of a generating
plant must ensure that no water is wasted and that water is recycled as much
as possible. One means of accomplishing this is to recycle the slurry water
and use it in the steam or cooling cycle. Another source, with which Nevada
Power has substantial experience, is the use of secondary sewage effluent.
Typically the coal fired plant will consist of: (1) the power block; (2) a
heat dissipation system; (3) coal handling and storage system; (4) emissions
control; (5) electrical switching; (6) wastewater management; (7) liquid/solid
waste handling and disposal; (8) lime supply and handling; (9) fuel oil; (10)
dust abatement; and (11) noise abatement and sanitary waste.
In the most modern baseload plants, coal is converted into heat at
nearly 90% efficiency. Turbo-generators then convert the thermal energy
into electrical energy at an efficiency of approximately 45%. The station
thus converts the thermal energy of coal into electrical energy at an effici-
ency of approximately 40%. However, additional coal is consumed to power
the auxiliary systems and the dewatering plant if a slurry pipeline is used to
transport the coal from the mines. The net energy available in the form of
electrical power is thus reduced to approximately 38%.
5-4
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A portion of the total energy in the coal will be expended to the envi-
ronment during the energy conversion process. Expenditures include;
a. Waste heat to the environment through the stack in the form of
thermal energy in the flue gases
b. Waste heat transferred to the atmosphere through the cooling towers
c. Energy expended through secondary sources such as thermal radia-
tion and convection from piping and equipment. Thus also includes
waste energy from the particulate and SO removal systems.
Lt
Many of the plants In the Southwest are currently using or plan to ex-
tensively use treated municipal wastewater and reclaimed water from the
coal slurry dewatering plants when these are used. The water is treated
appropriately and stored in ponds to maintain a specified number of days'
reserve. The ponds are lined with impervious native materials or synthetic
water barriers to control seepage into the ground.
Compared with photovoltaic power generation, a coal fired plant creates
air, water and thermal pollution directly, can inject water into the atmos-
phere, and requires coalmining.
The 30-year accrued land area dedicated to strip mining for coal may
be 60 to 160% of the land needed for this specific photovoltaic power plant.
This mined land is very difficult to reclaim, entirely aside from reconstitu-
ting its original contours. Surface water is adversely affected by siltation,
acid mine drainage, and altered hydrologic features.
Mining is currently the second most dangerous occupation, with an
annual fatality rate of 71 per 100,000. Deep mining requires (by comparison)
only negligible land commitment, but is more dangerous and more expensive
than strip mining.
Coal is a non-renewable resource. Although very extensive deposits
remain to be exploited, its use cannot continue perpetually. Further, it is
possible that the U.S. may need to dedicate much of its coal production to
conversion processes and to petrochemicals production.
5-5
-------
On balance, therefore, solar photovoltaic power generation seems pre-
ferable to coal environmentally, does not require the dedication of fossil
fuel, and may be safer occupationally. Solar photovoltaic costs, however,
remain completely non-competitive. To analyze the relative costs in the
light of national goals is outside the scope of this project.
Nuclear Power Generation
Nuclear power plants are not particularly attractive for use in elec-
trical power generation in those areas of the Southwest in which process
water is difficult to appropriate. Consequently, in arid regions with high
insolation typical of the sites where the first solar plants will be located,
the nuclear plant is not necessarily attractive. Further, lead times to pro-
duction of power are long (about 10 years) due to regulatory controls and
public controversy.
Hydroelectric Power Generation
A hydroelectric plant is presently located near the hypothetical plant
of this study. This plant is at the Hoover Dam on the Colorado River. The
back-water from this dam. forms Lake Mead. Because of the water require-
ments a hydroelectric plant is not a feasible alternative for the solar-electric
plant when it is to be located in an arid region.
Advanced Energy Sources
A number of advanced energy conversion systems are currently being
developed for use in the production of electrical energy. These include mag-
net ohydrodynamics (MHD) and potassium topping cycles, high temperature
turbines and direct conversion devices such as thermionic, thermoelectric,
electrogasdynamic systems, and wind energy systems. Of these, the MHD
topping systems in conjunction with regenerative steam cycles probably offer
the most promise in the near-term for base load generation. The high tem-
perature turbines may be used to meet peak power demands while the potas-
sium cycle and the direct conversion devices may be used as topping cycles
to improve the efficiency of the overall system.
5-6
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The MHD generator produces electrical energy directly from high tem-
terature thermal energy. The abundance of coal makes coal the most attrac-
tive fuel for the MHD generator with economics dictating the use of potassium
as the seed material for the gas stream. The predicted efficiency of a com-
bined MHD/steam turbine plant is in the range of 55 to 60%. This is nearly
twice the efficiency of nuclear plants.
The effluent problems associated with these advanced energy systems
(except for the wind powered systems) parallel those associated with the con-
ventional energy conversion systems (i.e., fossil or nuclear). For coal-fired
systems these include SO_, NO , particulates and thermal. The advanced
£ X
energy concepts in general have the potential to reduce thermal discharges
and conserve fuel supplies when compared with the conventional power plants
as a result of an improved energy conversion efficiency. Again the primary
disadvantage is the need for water for cooling.
Wind-powered systems will probably find their earliest applications as
suppliers of peak load needs for a network. The main requirement for the
wind power device is a steady wind. It seems very unlikely that wind power
stations can supply power in the quantities that we are discussing in the time
scale in which this solar plant is to function. Further, wind power is site-
specific. Suitable locations include the seacoast and the central plains, but
probably not the desert Southwest.
5.7 CLOSER PACKING DENSITY FOR SOLAR MODULES
In the baseline plant concept, the solar modules are spaced on 32.9 m
centers in a north-south, east-west rectangular grid pattern. This results
in a total land area, for a 1000 MW output, of approximately 52 km The
major consideration in module spacing determination, other than mechanical
clearance, is shadowing of one module by another. This is a prime tradeoff
area since closer spacing results in a savings in land area as well as in
interconnect cabling and access roads, but can cause plant power output
losses and operational perturbations. To show the relationship between
spacing (land area) and shadowing loss potential for the baseline plant, and to
5-7
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determine whether a land area reduction might be possible, a careful analysis
was made to determine the specific angular criteria for shadowing to occur.
Figure 5-1 shows how a typical module can shadow, in succession, modules
to its west, northwest, north, northeast and east. Assuming level terrain,
and using the baseline module dimensions and spacing, the following table
gives the calculated solar azimuth/elevation boundary conditions for shadow-
ing to occur:
TABLE 5-1. CONDITIONS FOR INTER-MODULE SHADOWING
Module
Affected
W
NW
N
NE
E
Solar
Azimuth Range
(deg)
59 to 121
114 to 156
149 to 211
204 to 246
239 to 301
Solar
Elevation
(deg)
19.3
12.7
19.3
12.7
19.3
For the latitude of the selected plant site, which determines the apparent
diurnal and seasonal movement of the sun, all shadowing occurs prior to
8:30 a.m. and after 3;30 p.m. (solar time) with the W and E shadowing occur-
ring mostly before 7:30 a.m. and after 4;30 p.m. all year, and the N shadow-
ing never occurring (at this latitude). The NW and NE shadowing can occur
prior to 8:30 a.m. and after 3:30 p.m. but only during the winter months.
When the north-south spacing is reduced from 32.9 to 24.4 m, the W, NW,
NE, and E shadowing is virtually unaffected but N shadowing becomes
severe during November and December, and during midday hours also.
Although the yearly average energy loss would probably be less than 10%,
the power fluctuations would not conform to normal operation of the utility
grid and therefore would probably be unacceptable. This analysis indicates
that although there is some potential for reducing the total land area occu-
pied by the plant, by perhaps 10 to 15%, the acceptability of doing so will have
to be determined by a detailed tradeoff study.
5-8
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North
Sun
Fig. 5-1. Inter-module shadowing,
5-9
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Because this hypothetical plant is sited on unused land without other
productive potential, increased land use efficiency (at the expense of reduced
generating capacity and output fluctuations) is probably not attractive.
5.8 OTHER SOLAR OPTIONS
For central station power generation, the major solar power options
are the thermal-type plant using either a large number of distributed thermal
collectors supplying heat to a central-receiver plant, or a central-receiving
plant in which a large field of mirrors focuses solar heat onto an elevated
receiver ("power tower") which in turn supplies heat to a steam-electric
plant. Compared to a photovoltaic plant (which at present would cost signifi-
cantly more) the thermal plants could have a substantially greater environ-
mental impact since much more waste heat is released. The release is
concentrated in the small area occupied by conventional cooling towers or
ponds. Assuming a heat rate of 7600 Btu/kWhr for a solar steam electric
plant, 1200 MW of power must be expended into the environment in cooling
towers, ponds, or rivers. By comparison this photovoltaic plant would ex-
pend about 200 MW, primarily in battery houses distributed over 52 km
Cooling towers could be natural or mechanical draft. The noise
emitted by the latter would not necessarily be audible at the facility perim-
eter. Wet towers would require water. However, Nevada Power (in whose
operating area this hypothetical facility is located) has extensive experience
using secondary sewage plant effluent for cooling water.
On balance, therefore, a solar thermal facility would create much
greater potential thermal pollution problems, but would not necessarily re-
quire natural waters. Recycling would reduce the quantities of nutrient
released to the environment. Cooling tower biocides and corrosion pre-
ventatives, drift, fog, and blowdown would be additional problems.
None of these problems are unique to solar steam electric power gen-
eration. A fossil or nuclear generating station would reject approximately
comparable quantities of waste heat and the same cooling options would be
5-10
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applicable. Photovoltaic power generation, being a direct energy conversion
process, is unique among currently envisioned technologies in that no central
cooling facilities are needed and no substantial amount of heat rejection
occurs.
Solar steam electric plants are projected to have greater overall effi-
ciencies of conversion of total available insolation to bus bar power. There-
fore, they are projected to require less land area for equivalent generating
capacity. By itself this is not a compelling consideration because the cur-
rent site is essentially non-productive waste land; capital equipment costs,
rather than land costs, are the overriding concern.
5-9 STORAGE OPTIONS
No Storage
One alternative is zero energy storage capacity with the plant supplying
power in accordance with available insolation. In addition to eliminating the
cost of battery systems, the inverter equipment cost could likely be cut in
half (with the regulator inputting power to simpler, undirectional inverters at
a fixed dc voltage). This approach would result in a lower capital expendi-
ture for the plant, but the plant would also be penalized by uncertain avail-
ability. This scheme might be acceptable if solar power represents a very
small portion of the utility network's capacity and the loss of the plant's out-
put due to transient cloud cover is not significant within normal fluctuations
in a large system. However, if solar power is to contribute appreciable
blocks of power to future utility networks, zero energy storage capacity will
most likely be unacceptable (Ref. 5-5).
Lead Acid Batteries
Although well developed and proven, the familiar lead-acid battery is
not considered competitive with the new lithium-sulfur cells for the following
reasons: Energy density is significantly lower, which would require a much
greater mass of battery material; the lead-acid battery is wasteful of lead
which could come into short supply; high charging rates cause boiling and
5-11
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H evolution and high discharge rates cause electrode pitting. For these
reasons it is believed that the total annual cost of a lead-acid battery storage
system would be considerably higher than the lithium-sulfur system, with no
environmental advantages.
Pumped Hydro Storage
The use of pumped hydro storage would require a high reservoir and a
low reservoir plus the necessary pumping and generation equipment. Cost
considerations usually require that the natural geography be suitable for such
a storage system. For the sites considered, the closest available reservoir
is Lake Mead. The use of Lake Mead would require that a reservoir be built
at a nearby site at a higher elevation. It is believed that such a facility would
have a greater environmental impact than battery storage technique. For this
reason, pumped hydro storage is not considered a viable alternative.
Hydrogen Cycle Storage
A hydrogen cycle storage system, which would consist primarily of
electrolysis cells, fuel cells, and a suitable hydrogen facility, in an attractive
alternate to the use of batteries and has been considered by various utilities
for load-leveling applications. At present, however, the projected cost per
kilowatt is higher and the overall turnaround efficiency is considerably lower
which further impacts total cost. For this reason, this storage method is
not considered a viable alternative this early in the development of the solar-
electric industry.
5.10 CONCLUSIONS
In conclusion, the proposed (hypothetical) photovoltaic power plant with
battery storage has several possible alternatives with regard to energy con-
version and storage, but appears to be justifiable with regard to conservation
of national energy resources and minimization of environment disturbance
caused by the large scale generation of electrical power.
5-12
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5.11 REFERENCES
5-1. Nevada Power Company. Environmental Assessment, Allen-Warner
Valley Energy System, Vol. Ill, Harry Allen Station, September 1975,
and Appendices Volume to Vol. III. September 1975, Las Vegas,
Nevada.
5-2. a. Palm, R. W. Selecting Preferred Sites for a Solar Power Station
Using Solar/Climatic Data. NASA CR-134667, Honeywell, Inc.,
Minneapolis, Minnesota, June 1974.
b. Palm, R.W. On-Site Survey of Candidate Solar/Electric Power
Plant Sites. NASA CR-134668, Honeywell, Inc., and Black & Veatch
Consulting Engineers, Kansas City, Missouri, June 1974.
c. Grosskreutz, J. C., R. R. Wood, and J.T. Vines. Site Selection
Guide for Solar Thermal Electric Generating Plants. NASA CR-
134669, Black & Veatch Consulting Engineers, Kansas City,
Missouri, 1974.
5-3. Grosskreutz, J.C. Criteria and Procedures for Siting Central
Solar (Thermal)/Electric Generating Stations. Black & Veatch
Consulting Engineers, Kansas City, Missouri, August 1974.
5-4. Sears, D. Richard, and P.O. McCormick. Preliminary Environ-
mental Assessment of Solar Energy Systems. IERL-Ci-101 (also
LMSC-HREC TR D496748), Lockheed-Huntsville Research & Engi-
neering Center, Huntsville, Alabama, February 1976.
5-5. Bechtel Corporation. A Preliminary Report on a Conceptual De-
sign of a Photovoltaic Central Station Power Plant. Prepared for
Spectrolab, Inc., under Subcontract No. 66725, San Francisco,
California, January 1976.
5-13
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SECTION 6
PROBABLE ADVERSE ENVIRONMENTAL EFFECTS
WHICH CANNOT BE AVOIDED
6.1 ECOLOGICAL EFFECTS
by W. Glen Bradley
As described previously in Section 4.1 (Ecological Impacts), severe
damage will occur to the soil surface, vegetation, and associated wildlife
during construction. Due to the solar-electric site design, which requires
placement of solar modules at short distances from each other, there may be
no way to avoid removal of most of the perennial vegetation and disruption of
much of the soil surface during the varied construction activities such as
heavy equipment movement, leveling, filling, and drilling. It must be recog-
nized that this is an extremely adverse effect which will increase soil ero-
sion by both wind and water and the establishment of vegetation not native to
the area. Both soil stabilization and vegetative recovery will be an ex-
tremely slow process requiring decades or possibly a century (6-1 and 2).
It should be further realized that even with mitigative measures the area
may not reestablish vegetative cover and soil surface approaching natural
conditions within the lifetime of the solar-electric plant. In fact, it is pos-
sible that pristine desert vegetation may never occur on the area again.
The characteristic desert vertebrate fauna found on the area will be
disrupted by removal of shelter, habitat, and food resources. Burrowing
animals, in particular, will experience high mortality and loss of shelter
during soil movement phases of construction. Additionally, there will be
dispersal of most vertebrate species into areas of similar habitat adjacent
to the construction site. Reestablishment of viable vertebrate population
after plant construction will be dependent upon the rate of reestablishment
of vegetation and soil stabilization. Vertebrate species composition and
6-1
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density during the extremely long period of vegetative recovery will be dif-
derent than that originally occurring on the area.
Only two species, the Desert Tortoise and the Kit Fox, which are
on the threatened and protected list of Nevada, occur in the area. High
mortality is to be expected for the Desert Tortoise due to destruction
of burrows which are used both as shelters and hibernals. This will be ac-
companied by dispersal of the remaining Desert Tortoises to adjacent areas
surrounding the solar-electric sites. Little or no mortality is to be expec-
ted for Kit Fox populations which have wide ranging activity patterns. Pop-
ulation dispersal will be into adjacent areas, and reestablishment on the
area will be dependent upon population density of prey, such as rodents and
rabbits.
6.2 VISUAL EFFECTS
The most obvious effect of this installation would be its visual impact.
Stretching for many miles within full view of traffic on Interstate 15 and US
93, the-project will conform exactly to the public concept of solar energy as
requiring commitment of vast land areas.
This visual effect is unavoidable at the proposed siting (Units 1 and 2).
It would be nearly as obvious in the alternative siting.
This visual effect may be undesirable if it causes the public to per-
ceive solar energy development as a threat to land values.
6.3 LOST RECREATIONAL VALUES
The only possible recreational uses of this site of which we are aware
are possible use for:
• Off-road vehicle touring and competition
• Amateur archaeological and historical artifact
collecting.
6-2
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Both of these activities are currently discouraged, controlled, or even
prohibited on some Federal lands. They are considered undesirable and de-
structive by many authorities. The loss due to this project is unavoidable.
Some sectors of the public may regard this loss as adverse.
6.4 SOCIO-ECONOMIC EFFECTS
Numerous social, demographic, economic, and community effects will
occur, that are beyond the scope of this task to analyze. As indicated
briefly in Section 4.13, all of these effects are thought to be very small
viewed in the light of projected growth for this region.
A possible exception is the demands placed on the skilled crafts man-
power pool of the area, in which manufacturing and construction are not
prominent.
The project is expected to cause an influx of skilled craftsmen who
might experience difficulty finding local employment after the project is
complete.
6.5 ATMOSPHERIC EMISSIONS
Fugitive dust emissions are anticipated due to grubbing, grading, and
vehicular traffic on unpaved terrain. While dust suppressants can be ap-
plied, it is not economically feasible to prevent all dust emissions. Using
modern construction engineering practices, it will be possible to comply
with current Clark County, Nevada, and USEPA fugitive dust regulations
(of Section 1.5).
6-3
-------
6.6 REFERENCES
6-1. Wallace, A., and E. M. Romrney. Revegetation in Areas Damaged by
Close-in Fallout from Nuclear Detonations. In: Radioecology and
Ecophysiology of Desert Plants at the Nevada Test Site. ERDA Report
TID-25954, pp. 279-282.
6-2. Wells, P. V. Succession in Desert Vegetation on Streets of a Nevada
Ghost Town. Science, 134:670-671, 1961.
6-4
-------
SECTION 7
MITIGATION OF AVOIDABLE IMPACTS
7.1 ECOLOGICAL IMPACTS
(by W. Glen Bradley)
Reestablishing Vegetation
Potential mitigative measures are numerous and varied and are de-
pendent largely upon the monetary expenditure provided during plant con-
struction and early stages of plant operation. It it, highly recommended that
a professional ecologist be employed prior to site construction. This person
sould be responsible for development of an overall plan for mitigative meas-
ures to be employed during plant construction and operation. This would not
only allow mitigation of avoidable impacts but reduce the intensity of unavoid-
able ecological effects during construction.
Plans should be developed prior to construction which will allow mini-
mal disruption of soil surface and removal of perennial vegetation. It is
realized that these plans will have to be developed in coordination with con-
struction engineers within the general framework of what is technologically
and economically feasible. It is extremely important, however, that widely
distributed islands of intact perennial vegetation remain on the area after
construction to provide seed reserves for vegetative recovery. This would
retard soil erosion. Resulting hazards of brush wildfire need to be monitored
continuously.
Installation of microcatchment basins for water and reestablishment of
vegetation has been used in Israel (Ref. 7-1). For example, in one study it
was found that a 500 m basin produced optimum retention; when basin size
was reduced so was moisture retention and vegetative recovery.
7-1
-------
The distance between the circles swept out by module corners is 13.05
m. An 8 m catchment basin would have an area of 50 m , and would leave a
2.5 m vehicle passage (on each side) between its rim and the nearest corner
of a module. Although only 10% of the basin area found necessary in the
Israeli study, such shallow depressions (perhaps only 0.6 m deep), would
greatly increase chances of recovery of vegetation.
Revegetation of basins could be a combination of transplanting of desert
shrubs and seeding by artificial or natural means. It is strongly recom-
mended that initial attempts be made to transplant native shrubs into the
catchment basin to aid in natural recovery. Plant construction will be in
phases. In each area, shrubs can be removed during construction and trans-
planted to previously developed areas. It is recognized that construction of
basins and transplanting of native shrubs would involve considerable expendi-
ture of manpower and funds. This mitigative measure, however, would pro-
vide maximal opportunity for reestablishment of native vegetation at a more
rapid rate and greatly enhance the possibility of establishment of vegetation
which would retard soil erosion and promote soil stabilization, (cf. our
earlier discussion of shading and rainfall spalsh effects.)
Hydromulching or hydroseeding is a method of application of seed into
soil by high pressure water spray (Ref. 7-2). This technique has recently
been developed and is in use for seeding slopes of newly constructed high-
ways. Seed, fertilizer and nutrients are mixed together in a slurry. The
slurry is mixed in holding tanks and then sprayed by use of high pressure
pumps onto the soil surface. Various mulches can be used, including straw
held together by oil, or more recently wood fibers or fiberglass in a light
resin. Although hydroseeding has usually involved sowing grass seeds, the
technique is adaptable for seeding native plant species, both herbaceous and
perennial. Seeds of native shrubs and herbs may be obtained commercially
and in large quantities by special order (Ref. 7-3). A mixture of herb and
shrub seeds is recommended for hydroseeding. This would promote estab-
lishment of a variety of native species on the area. Germination require-
ments, particularly soil moisture and temperature, are highly variable
between.plant species. Use of a variety of native seeds would increase the
7-2
-------
probability of successful germination, establishment, and development of
plant cover. Large scale application of these methods should be preceded
by on-site test plot experiments.
Seeding should occur in fall and winter months to take advantage of the
cooler temperature and available soil moisture. Additionally, the cooler
temperatures during this period are important in breaking seed dormancy.
Some native species, however, may have to be treated with sulphuric acid or
mechanical rubbing for seed scarification to promote germination. Trans-
planting of desert shrubs is most successful in the spring, especially if ade-
quate soil moisture is present. A major problem commonly experienced in
seeding and transplanting in arid regions is damage to seedlings or trans-
plants by rabbits or rodents. Various poisoning programs have been used
in the past to effectively control damaging populations of these animals. In
recent years, government regulations have largely prohibited the use of
poisons to control animal populations. If this problem occurs during rees-
tablishment of vegetation, effective control of rodent populations can be
achieved through intensive snap-trap programs for selected areas. Rabbits
can be effectively controlled by nighttime hunting from vehicles using spot-
lights when permitted by game laws.
Soil erosion and removal of perennial vegetation are the most
prominent adverse environmental effects which would occur on the area dur-
ing construction and be maintained throughout plant operation. It is strongly
recommended that mitigative measures involving minimal destruction of
perennial vegetation and soil surface, development of microcatchment basins
accompanied by transplanting of perennial vegetation, and hydroseeding
throughout the solar-electric sites be employed. These measures would
greatly reduce soil erosion by speeding up the processes of soil stabiliza-
tion and vegetative recovery. They would also greatly enhance the rate of
vegetative reestablishment, reduce the intensity of invasion by weed species,
and increase the probability for the successful reestablishment of native
plant species.
7-3
-------
Minimizing Impacts of Construction on Animal Populations
Previous discussion has indicated that animal populations will be af-
fected to varying degrees by construction activities which will deplete shelter
and food resources and destroy burrows and hibernals. Relatively high mor-
taility is to be expected for burrowing animals such as rodents, lizards,
snakes, and Desert Tortoises. This is particularly true during periods of
hibernation. It is not practical to consider measures to reduce mortality for
most burrowing animals except possibly to concentrate soil moving activities
during spring, summer, and early fall. Special measures should be taken to
minimize mortality of Desert Tortoise populations since it is on the List of
the threatened species as established by Nevada Fish and Game. All burrows
should be located immediately prior to construction and checked for occu-
pancy. Desert Tortoises should be removed and relocated to suitable habitat
outside the area with cooperation of Nevada Fish and Game. This procedure
is absolutely necessary during colder months of the year when tortoises will
be located within hibernal burrows. In many instances, these are of suffi-
cient size that they will have to be excavated to determine occupany.
The major mitigative measures to minimize long-term damage to
animal populations have been described previously in the section, "Reestab-
lishing Vegetation." As soil stabilization and revegetation occurs, most
species will disperse and-reestablish themselves on the solar-electric sites.
Conclusions
Mitigative measures have been proposed to accelerate successional
sequences leading to the reestablishment of native vegetation and soil stabi-
lization. In addition, it is recommended that Desert Tortoise be removed
and relocated prior to construction. Mitigative measures recommended to
achieve the above objectives include the following: (1) employment of a pro-
fessional ecologist to develop procedures for minimal destruction of soil
surface and perennial vegetation during construction; (2) promote vegetative
recovery and soil stabilization by requiring intact islands of perennial vege-
tation to be preserved on the sites, development of microcatchment basins,
transplanting of perennial shrubs, and hydroseeding of native herb and shrub
7-4
-------
species throughout the solar-electric sites; and (3) relocation of threatened
Desert Tortoise populations in cooperation with the Nevada Fish and Game.
7.2 SOCIO-ECONOMIC IMPACTS
As discussed earlier, it is proposed to actively discourage develop-
ment of construction villages, and actively encourage contractor and sub-
contractor employees to live in the Las Vegas urban area or in Moapa Valley.
Among mechanisms for doing this are to:
• Establishment of a commuter bus service from
Las Vegas.
• Coordination with realtors in the Las Vegas
area,
7.3 ATMOSPHERIC EMISSIONS
Plastic reflector substrate suffering photolytic or thermal degradation
is likely to emit gaseous products (cf. Sections 1.2 and 4.5). As indicated
previously, material exhibiting significant degradation is economically un-
desirable, and therefore is not likely to be chosen deliberately. To forestall
inadvertent selection of an undesirable material, we suggest that an active
R&D program be pursued. This should include accelerated life tests as
well as spectroscopic and gas chromatographic studies of exposed plastic
and emissions generated, respectively.
A program of dispersion -modeling for this large distributed (class B)
source is desirable ultimately, but probably premature at this time.
7.4 REFERENCES
7-1. Evenari, M., L. Shanan, and N. Tadmor. The Negev: The
Challenge of a Desert. Oxford University Press, London, 1971. 345pp.
7-2. Baciu, E. Hydro-Seeding. Proceedings International Plant
Propagators' Society, 17:110-111, 1967.
7-3. Native seeds can be obtained commercially from the following
companies: Environmental Seed Producers, Inc., P. O. 1196,
El Monte, California, 91734 and/or Peacoff Brothers Nursery
and Seed Company, Route 5, Box 215-R, Escondido, California, 902025.
7-5
-------
SECTION 8
RELATIONSHIP BETWEEN LOCAL SHORT-TERM USE
OF MAN'S ENVIRONMENT AND THE MAINTENANCE
AND ENHANCEMENT OF LONG-TERM PRODUCTIVITY
8.1 LAND USE BENEFITS
At the present time there is no productive utilization of the land pro-
posed for Units 1 and 2. Soil conditions preclude use for agricultural pur-
poses even with irrigation. There is one mining claim, of unknown value
and validity, on this land near U.S. Highway 93 about 1.6 km from U.S. Inter-
state 15. Therefore, the principal attributes of this land are its topography
and its proximity to already existing transportation and power transmission
corridors.
The proposed hypothetical land use is an unusually appropriate means
to convert this land to productivity because of the site's geographical location
with respect to load centers, its climate and insolation, and because the pro-
posed project requires no process water whatsoever.
8.2 DECOMMISSIONING
Decommissioning of the plant would involve dismantling and salvaging
all module structures for scrap value, and removal of all plant facilities
except subgrade foundations and some of the buildings.
We assume that a replacement generating station will have been built
somewhere - prior to decommissioning of this facility. Continuing projected
load growth in this region will probably require additional generating capacity
however. This site, after removal of residual structures, will continue to be
unusually suitable for siting of facilities not needing process water - particu
larly solar photovoltaic installations. After decommissioning, the land wil.
8-1
-------
be cleared, graded, and left with internal roads, rail and highway access,
security fence and a few residual buildings. Therefore, it will have enhanced
value also as an industrial site.
8.3 POWER CONTRIBUTION
This project is expected to supply about 7% of the utility system's pro-
jected generating capacity in the late 1980s. Over the 30-year projected life
of this facility, 26 x 109 kWhr of electricity will be generated assuming an 0.50
capacity factor. This will be consumed largely in Las Vegas and Los Angeles.
9 3
Las Vegas alone consumed 4.2x10 kWhr in 1974, or about 11x10 kWhr per
capita. Projected population growth exceeds 16,000 annually. At current elec-
tricity consumption, this corresponds to an annual demand growth of 176x10
Q
kWhr (or 4.2% of 1974 consumption) or 5.3x10 kWhr over 30 years.
8.4 TAX REVENUES
P_ropei-ty__T_axes
Q
Based on 1976 dollars, a total capital cost of $1.67 x 10 is projected
for the hypothetical plant. Construction is to be phased and segments of the
plant are to go on line as constructed. Estimated property taxes (Table 8-1)
are calculated assuming a linearly increased investment and assessed value
over 10 years, 30 years operation at 3% depreciation, and 5 years linear re-
duction to zero value.
Sanitation District Payments
The estimated 23 m /day requirements for potable water (including
visitor center needs) amount to 8300 m /yr. Water will be purchased from
Clark County at $81.37/10 m or $674/yr, a trivial contribution to county
finances.
53 K. r>
For the required 8 x 10 m construction concrete, 1.4 x 10 m
water will be required. This will be the responsibility of the concrete
batcher. Even if potable water were used, this would represent only a
8-2
-------
TABLE 8-1. ESTIMATED PROPERTY TAX REVENUES FROM PROPOSED
SOLAR-ELECTRIC STATION ($ MILLIONS)
Year After
Go -Ahead
0
5
10
15
25
30
35
40
45
Depreciated
Value @ 3%
0
835
1670
1434
1231
1057
908
450
0
Assessed*
Valuation
0
292
585
502
431
370
318
158
0
Property
Clark Co+
0.0
13.00
26.04
22.34
19.18
16.47
14.15
7.03
0.0
Jt
Taxes""
Nye Co.++
0.0
0.112
0.225
0.193
0.166
0.142
0.122
0.061
0.0
35% of actual valuation.
ijrf >jf
' 'Allocated by single-wire-mile method, 98.9% to Clark County, 1.1% to
Nye County.
+$4.50/$100.
++$3.50/$100.
$11,090 total payment to the Clark Co. Sanitation District, or an additional
$1400/yr. during the foundation preparation phase. This represents a trivial
contribution to the Clark County economy.
8.5 OTHER ECONOMIC BENEFITS
Employment and Income
Peak direct employment during construction will be about 1000, with
potential secondary induced employment of 1600.
Significant numbers of the construction workers will come from out-
side the county, but will live and pay taxes in Clark County during their em-
ployment. Operating personnel and secondary induced employment totalling
about 130 persons, represent a small contribution to the workforce in Clark
County. The annual construction payroll would peak at about $14 x 10 .
8-3
-------
Other Financial Sectors
It is beyond the scope of this task to estimate the impact of this work-
force and the construction project investments upon retail trade and other
economic sectors. The effect will be significant, but in general all economic
effects will be dwarfed by the county's projected growth (without the project)
for the remainder of the century.
8.6 COSTS
Incremental Community Services and Facility Costs
These costs are estimated by assuming the basic accuracy of the costs
projected in the Harry Allen assessment (Ref. 8-1) and scaling those costs as-
suming they are linear with workforce. During the peak workforce years,
\
approximately 2 to 9 years after go-ahead, the incremental costs are indi-
cated in Table 8.2.
TABLE 8-2. INCREMENTAL COMMUNITY COSTS
FOR SERVICES AND FACILITIES
Service
Schools
Sewer
Water
Police
Fire
Solid Waste
Total
$ x 103
263
15
55
82
46
11
412
Environmental Costs
As discussed in Sections 2.9, 4.1, 6.1 and 7.1, there will be some direct
and indirect ecological effects, but no species are expected to be endangered
or threatened. Inevitable losses of vegetation followed by partial regrowth
8-4
-------
of different vegetative cover will possibly lead to long term or permanent
reductions in numbers of some vertebrate and invertebrate species on the
site.
No long-term adverse effects on either atmospheric or water quality
can be identified. No significant thermal pollution is created.
Visual (aesthetic) effects will be inevitable and long term. Not all ob-
servers will regard them as adverse, but many will. Because the land pro-
posed for use is wasteland described as having below average scenic value,
actual "visual costs" (if they could be quantified) would be minor.
Recreational Costs
The current use of this land for major off-road vehicle competitions
would be precluded by installation of the solar electric plant. Such use would
need to be prohibited even on adjacent areas, in order not to adversely in-
crease the dust burden on solar collectors.
Mineral Extraction
The one mining claim extant, the Old Witch Mine, is of unknown value.
The Bureau of Land Management has not yet investigated or validated the
claim. Even should the claim be validated and a mine established, this would
not necessarily conflict with the proposed action if operators use shaft or
drift operation. No independent field analysis of the mineral potential of this
area was done for this report.
8.7 REFERENCE
8-1 Nevada Power Company. Environmental Assessment, Allen Warner
Valley Energy System, Volume III Harry Allen Station, September
1975; and Appendices Volume to Volume III, September 1975, Las
Vegas, Nevada.
8-5
-------
SECTION 9
IRREVERSIBLE AND IRRETRIEVABLE COMMITMENTS OF RESOURCES
INVOLVED IN THE PROPOSED ACTION
9.1 SILICON
Production of arrays which will put out 1000 MW (peak) using 0.15 mm
thick, 20% efficient, silicon solar cells with overall production yield of
34.8% requires 5x10 kg of pure polycrystalline silicon. This is less than
four times the estimated total semiconductor silicon production in 1974 and
about 6% of the 1968 United Sates production of 99% pure silicon (metallurg-
ical grade). The U.S. reserves of SiO2 which may be used to produce
silicon are so greab that they have not been completely catalogued. The
level of utilization of silicon solar cells is limited by economics--not by
resource availability (Ref. 9-1).
9.2 STEEL
Steel requirements are listed in Table 9-1, and compared with supply/
demand data in Table 9-2. The station requirement of 835 x 10 kg steel
(almost 10 tons) is seen to represent a small fraction of U.S. reserves.
Spread over seven or eight years, the station requirements would represent
only a trivial amount of U. S. production.
9.3 CEMENT
Station requirements are about 260 x 10 kg of cement, or about 32 x
106 kg/yr. By comparison, the neighboring Apex plant of U.S. Lime Prod-
ucts Division, Flintkote Company, produces about 450 x 10 kg of calcined
lime annually. Other raw materials in Portland cement production are
equally abundant.
9-1
-------
TABLE 9-1. STEEL REQUIREMENTS FOR
50,000 MODULE ARRAY*
Steel, kg
Component Per Module Entire 1000 MW Array
Rotating Structure
Collectors
Superstructure
Wheels and Pillow Blocks
Connectors and Fasteners
Subtotal
7285
4898
531
381
13096
_
—
655 x 106
Substructure and Foundations
Center Support (including rebar) 767 —
Track Assembly Z845 —
Subtotal 3612 181 x 10
Total Steel 16709 835 x 106
*Ref.9-2.
TABLE 9-2. STEEL SUPPLY/DEMAND DATA
COMPARED WITH STATION REQUIREMENTS
Datum Steel, 106 kg
Station Requirements 835
U. S. Reserves 2,000,000
U. S. Annual Consumption 128,000
World Production 574,000
*Ref. 9-3.
9-2
-------
9.4 WATER
Construction water is needed principally for concrete production. Re-
quirements are about 1.4 x 105 m3. Although its transport is costly, water
is available.
9.5 COAL
Coal is required to produce metallurgical coke, used in both silicon
and steel production. The 1000 MW of generating capacity of solar cells
will require only about 70 x 10 kg coal, assuming 70% coking yield (Ref.
9-1).
9.6 LITHIUM
Battery storage units require approximately 2.4 x 10 kg lithium.
U. S. production in 1974 was 3.4 x 10 kg, with rest-of-world production
1.6 x 10 kg. Assuming installation over approximately eight years, batter-
ies for this plant would represent about 10% of 1974 annual production each
9
year for eight years. One estimate of U-S. reserves is less than 10 kg;
industry estimates are much more optimistic (Ref. 9-4). Lithium may be
demand limited if major competing uses develop (e.g., nuclear fusion or
electric vehicles).
9.7 OTHER
Human resources and land commitment have been discussed in some
detail previously. Basically, the human requirements are small, and occur
partly in crafts beset by chronic unemployment.
Land resource commitment is large, especially if projected to the
day when 106 MW are generated by solar electric plants. However, this
particular hypothetical plant is sited on wasteland where principal current
use is destructive recreation (off-road racing).
9-3
-------
9.8 REFERENCES
9-1. M. G. Gandel, P. A. Dillard, D. R. Sears, S. M. Ko and S. V. Bourgeois,
Assessment of Large Scale Photovoltaic Materials Production, LMSC-
HREC TR D497252, Lockheed Huntsville Research & Engineering Center,
Huntsville,.Alabama, July 1976.
9-2. Davidson, Joseph K., and H. Lundgren. Letter report to Spectro-
lab, Inc., on a "Conceptual Design of a Photovoltaic Central Station
Power Plant (Module)," Ingenasu Associates, Tempe, Arizona,
May 1976.
9-3. U.S. Nuclear Regulatory Commission. Draft Environmental Impact
Statement, Palo Verde Nuclear Generating Station, Washington,
D.C., April 1975.
9-4. Hammond, A.L. Lithium; Will Short Supply Constrain Energy
Technologies.? Science , Vol. 191, 1976, p. 1037.
9-4
-------
SECTION 10
INTERESTS AND CONSIDERATIONS OF FEDERAL
POLICY THOUGHT TO OFFSET THE ADVERSE
ENVIRONMENTAL EFFECT
It is beyond the scope of this task to analyze the relevant Federal
policies. The following list contains those thought to be most significant
or most relevant:
• To develop increased independence from imported
fuel supplies, by developing non-resource deplet-
ing domestic energy supplies
• To maintain air quality standards by avoidance of
fossil fuel combustion
• To avoid further appropriation and deterioration of
natural waters —particularly those subject to inter-
national agreement (the Colorado River) and those
in arid regions (South Nevada)
• To improve the productivity of lands now lying waste
• ' To improve the U.S. balance of payments by avoiding
fuel imports
• To emphasize utilization of regenerable resources
(e.g., sunlight)
• To encourage private-sector employment in trades
or geographical areas suffering chronic episodes of
high unemployment
10-1
-------
SECTION 11
SECONDARY IMPACTS
11.1 POLLUTIONAL EFFECTS OF THE SILICON SOLAR CELL MANU-
FACTURING INDUSTRY
In a companion report (Ref. 11-1), Qandel et al have examined the en-
vironmental problems associated with photo voltaic-grade silicon and silicon
solar cell manufacture. These authors identify the following pollutant re-
leases:
• Indirect pollution resulting from large power
consumption in Si and cell production
• SiO dust of unknown particle size distribution
• Si dust of unknown particle size distribution
» NO and SO-,
X- L*
• SiF4 (and hence H2F2)
• Air and water pollution from coking, coke
pushing, and coke quenching
• Airborne SiC dust of unknown particle size
distribution
• Disposal of cutting sludges containing oils,
clays, abrasives, adhesives, and inert metals
• Disposal of scrubber sludges, containing
Ca (OH)2 and CaF2.
The same report contains -material balances for most of the raw materials
and identifies some additional waste streams. Total power consumption
of a production facility producing finished cells starting with quartzite is.
about 1 MW for every megawatt's worth of annual production of generating
capacity. That is, to say, the factory producing in one year the cells for this
hypothetical 1000 MW solar power plant would consume energy at the rate of
1000 MW (three shift operation).
11-1
-------
11.2 SOCIO-ECONOMIC EFFECTS
Socio-economic and community effects are discussed briefly in Section
4.13. It was beyond the scope of this task to present an analysis in the depth
needed to evaluate secondary consequences. It is suggested, however, that
the reader examine the Harry Allen assessment to study in some detail the
effects of a major power plant project on demographic, socio-economic, and
community characteristics in extreme southern Nevada. Scaling of work
force, capital requirements, and power contribution, and adjustments in the
timing and manpower loading analysis would be required.
11.3 EFFECTS ON TRANSPORTATION SYSTEMS
This project would place major demands on transportation systems,
especially highway and rail. Similar demands would be created by 1000 MW
solar steam-electric plants, which are likely to be built before photovoltaic
plants.
We recommend that an analysis of the impact of solar generating sta-
tions on traffic systems precede actual plant construction with ample lead
time to effect the needed expansion or modifications in these systems.
11.4 REFERENCE
11-1. M. G. Gandel, P. A. Dillard, D. R. Sears, S. M. Ko and S. V. Bourgeois
"Assessment of Large Scale Photovoltaic Materials Production "
LMSC-HREC TR D497252, Lockheed-Huntsville Research & Engineer-
ing Center, Huntsville, Alabama, July 1976.
11-2
-------
SECTION 12
COORDINATION
Many agencies and contractors were consulted during the course of
this study. The following personnel supplied reports or other information
critically important to this project or granted release to use and quote
unpublished material. They are listed in approximate chronological order.
1. Dr. Morton B. Prince
Chief, Photovoltaic Branch
Division of Solar Energy
Energy Research and Development Administration
Washington, DC 20550
2. Mr. Terry Hoffstra
EIS Office, USEPA Region VI
1600 Patterson St.
Dallas, TX 75201
3. Mr. Gary Parker
Office of Energy Activities
USEPA Region VIII
1860 Lincoln St.
Denver, CO 80203
4. Dr. B. W. Marshall
Solar Energy Systems Division
Sandia Laboratories
Albuquerque, NM 87115
5. Mr. D. Cain
Environmental Coordinator's Office
Bureau of Land Management
Salt Lake City, UT 84111
6. Mr. John W. Arlidge
Nevada Power Company
Box 230
4th St. and Stewart Ave.
Las Vegas, NV 89151
12-1
-------
7. Mr. Hal Isaacs
Environmental Project Office
Bureau of Land Management
P. O, Box 851
Cedar City, UT 84720
8. Mr. D. Gilmore
USEPA Environmental Monitoring and Support Laboratory
P. CX Box 15027
Las Vegas, NV 89114
9. Dr. F. T. C. Bartels
Spectrolab Inc.
12500 Gladstone Ave.
Sylmar, CA 91342
10. Mr. Albert A. Chilenskas
Mgr. Commercial Development
Argonne National Laboratory
9700 S. Cass Ave.
Argonne, IL 60439
11. Mr. Lloyd Rooke
Soil Conservation Service
U.S. Department of Agriculture
Las Vegas,' NV 89151
12. Mr. Donald J. Wilkes
Information Division
Bldg. 2028
Oak Ridge National Laboratory
P. O. Box X
Oak Ridge, TN 37830
13. Mr. Paul Brannon
Environmental Research Division
Organization 54-43
Sandia Laboratories
Albuquerque, NM 87115
12-2
-------
Appendix A
CONVERSION FACTORS
The bulk of this report uses metric units rather than English. How-
ever, American practice in the electrical utilities industry, public land
records, and finance remains non-metric. The following tables will assist
the reader in necessary conversions.
TABLE A-l. METRIC-TO-ENGLISH CONVERSION FACTORS
To Convert
From
Kilometers
Meters
Kilometer s/hr
Hectares
Kilograms
Kilograms
Cubic Meters
Cubic Meters
Cubic Meters
Cubic Meters
Abs. Joule sec" (Watts)
Abs. Joule
To
Miles
Feet
Knots
Acres
Pounds
Tons
Cubic Feet
Cubic Yard
Gallons
Acre-Feet
Horsepower
kWhr
Multiply
0.6215
3.279
0,5400
2.469
2.205
1.102 x
35.34
1.307
264.20
2.296 x
1.340 x
2.778 x
by
io"J
io"5
io"3
_7
10
A-l
-------
TABLE A-2. ENGLISH-TO-ME TRIG CONVERSION FACTORS
To Convert
From
Miles
Feet
Knots
Acres
Pounds
Tons
Cubic Feet
Cubic Yard
Gallons
Acre-Feet
Horsepower
kWhr
To
Kilometers
Meters
Kilo mete r s/hr
Hectares
Kilograms
Kilograms
Cubic Meters
Cubic Meters
Cubic Meters
Cubic Meters
Abs. Joule sec"1 (Watts)
Abs. Joule
Multiply by
1.609
0.305
1.852
0.405
0.4536
907.2
0.0283
0.765
3.785 x 10"3
43560
746
3.6 x 106
A-2
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Appendix B
GLOSSARY OF TERMS AND ABBREVIATIONS
ac
Array
BLM
Breeze
CF
Collector
dc
EPA
Group
GW
e
Heat Rate
MSL
MT
MW
e
NPDES
PCM
SCR
Solar Module
Unit
alternating current
the 52 km assembly of 500 groups (50,000 modules)*
Bureau of Land Management
airborne coal dust
capacity factor = ratio of energy actually produced to
maximum amount possible, over period of operation
a single parabolic trough primary supporting a single
Winston secondary containing a string of photovoltaic
cells (inset, Figure 1-3) .
direct current
Environmental Protection Agency
an electrically interconnected set of 100 modules
(Figure 1-2)*
gigawatt electric = 10 kW (see MW )
fuel heat input required to generate a kWh. Commonly
expressed in Btu/kWh
mean sea level
metric ton =10 kg
megawatt electric (10 kW electric power actually
produced as distinct from heating value of fuel
consumed)
National Pollution Discharge Elimination System
power conditioning module. The pair of buildings
comprising battery storage, regulator, and inverters,
etc., servicing one group of 100 modules (Figures
1-5 and 1-6)*
silicon controlled rectifier
a single sun-tracking, rotating structure, containing
14 collectors (Figure 1-3)*.
one of the two geographically separated sections
of the plant (Figure 2-if.
^Definition specific to this report. May not apply in other contexts.
B-l
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TECHNICAL REPORT DATA
(Please read Imtnicrioits on the reverse be fare completing)
1. REPORT NO. 2.
EPA-600/7-77-085
4. TITLE AND SUBTITLE
Environmental Impact Statement for a Hypothetical
1000 MWp Photovoltaic Solar-Electric Plant
S. REPORT DATE
Aucrust 1977 issuing datp
G. PERFORMING ORGANIZATION CODE
' AUTMORlS)
D. Richard Sears, Donald V. Merrifield,
Morris M. Penny and W. Glen Bradley
8. PERFORMING ORGANIZATION RfcPORT NO
LMSC-HREC TR D497914
3. RECIPIENT'S ACCESSION-NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Lockheed Missiles & Space Company, Inc.
Huntsville Research & Engineering Center
Huntsville, Alabama 35807
10. PROGRAM ELEMENT NO.
EHE 624B
11. CONTRACT/GRANT NO.
Contract No. 68-02-1331,
Task Order 14
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Lab-Gin. , Oti
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati. Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final 4-1-76 through 7-31-76
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This draft EIS was prepared to assist the EPA in strengthening its inputs to
environmental impact statements in the area of new energy developments. The
document has no legal significance, and the "proposed action" is entirely hypo-
thetical. The hypothetical plant is 1000 MWe silicon photovoltaic, located on 52
of desert near Las Vegas, Nevada. It has a 3-hour storage capacity.
The principal adverse environmental impacts expected relate to the destruction
of soil and vegetation on 52 km^ of desert terrain. Revegetation is expected to be
Very slow without human assistance. Numerous animals will be displaced tem-
porarily or permanently.
The visual impact of this project will be extensive, and no measures are known
to minimize the impact.
There will be no effect on ground water, no thermal pollution, no surface water
pollution, no noise pollution, and no effect on local historical, archaeological, and
cultural values.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
Pollution
Solar cells
Storage generators
Environmental engineering
Land use
3. DISTRIBUTION STATEMENT
Release unlimited
c. COSATI Field/Group
environmental impact
desert ecology
Nevada
Solar power plants
19. SECURITY CLASS (This Report}
Unclassified
20. SECURITY CLASS (Thispage)
Unclassified
10A
10B
IOC
13B
13H
21. NO. OF PAGES
206
22. PRICE
EPA Form 2220-1 (9-73)
OU.S. GOVERNMENT PRINTING OFFICE: 1977-757-056/6511
B-2
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