Project Narrative Report - Sempra US Gas & Power, LLC

27 Pages·2014·0.26 MB·English

Maricopa County
Major Amendment Z2013099
Minor Amendment Z2012052
Minor Amendment Z2010073

Special Use Permit Z2009022

Mesquite Solar Energy Project
Project Narrative Report

Submitted by

December 28, 2013
Mesquite Solar Energy Project—SUP Application
Table of Contents
Page
1.0 Project Name and Location ....................................................................................... 1
1.1 Project Name ................................................................................................... 1
1.2 Location ........................................................................................................... 1
2.0 Purpose of Request .................................................................................................... 2
2.1 Expansion of the Project Site .......................................................................... 2
2.2 Project Benefits ............................................................................................... 2
2.3 Site Suitability .................................................................................................. 2
3.0 Previous Approvals .................................................................................................... 3
3.1 CPA 200005 and SUP Z2000071 (Water Property) ........................................ 3
3.2 CPA 200807 and SUP Z2008066 (Original Site) ............................................. 3
3.3 SUP Z2009022 and Amendments (Original Site) ............................................ 3
3.4 CPA 200910 (Expansion Area)........................................................................ 4
3.5 Other Previous Approvals ................................................................................ 4
4.0 Facility Description .................................................................................................... 5
4.1 Overview ......................................................................................................... 5
4.2 Solar Field ....................................................................................................... 5
4.3 Electrical Collection System ............................................................................ 6
4.4 Substation ....................................................................................................... 6
4.5 Driveways ........................................................................................................ 7
4.6 Drainage Design .............................................................................................. 7
4.7 Grading Design................................................................................................ 8
4.8 Screening Berm and Landscaping ................................................................... 8
4.9 Fencing ............................................................................................................ 9
4.10 Administration Building .................................................................................... 9
5.0 Construction ............................................................................................................. 11
5.1 Project Phases and Schedule........................................................................ 11
5.2 Construction Workforce and Workspace ....................................................... 11
5.3 Site Preparation and Grading Activities ......................................................... 11
5.4 Equipment Installation ................................................................................... 12
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Mesquite Solar Energy Project—SUP Application
6.0 Operation................................................................................................................... 13
6.1 Operation Workforce ..................................................................................... 13
6.2 Facility Maintenance ...................................................................................... 13
6.3 Site Security .................................................................................................. 13
6.4 Weed Management and Dust Control ........................................................... 13
7.0 Health and Safety ..................................................................................................... 14
7.1 Health and Safety Program ........................................................................... 14
7.2 Fire Protection ............................................................................................... 14
7.3 Emergency Management Plans ..................................................................... 15
8.0 Land Use and Community Resources .................................................................... 16
8.1 Land Use on the Project Site and Surroundings ............................................ 16
8.2 Site Access and County Right-of-Way ........................................................... 17
8.3 Traffic Circulation ........................................................................................... 17
8.4 Community Facilities and Services ................................................................ 18
8.5 Public Utilities and Services........................................................................... 18
9.0 Environmental Resources ....................................................................................... 19
9.1 Noise ............................................................................................................. 19
9.2 Air Quality ...................................................................................................... 19
9.3 Visual Resources ........................................................................................... 19
9.4 Water Resources ........................................................................................... 19
9.5 Biological Resources ..................................................................................... 19
9.6 Cultural Resources ........................................................................................ 21
9.7 Soil Resources .............................................................................................. 22
9.8 Waste and Hazardous Materials Management .............................................. 23

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Mesquite Solar Energy Project—SUP Application
Photographs
Photograph 1: Solar Panels in an Array .................................................................................. 5

Tables
Table 1: Surrounding Land Use .................................................................................. 16

Figures
Figure 1: Plot Plan and Surrounding Land Uses
Figure 2: Solar Radiation and Project Location
Figure 3: Electrical Collection System and Substation One-Line Diagram
Figure 4: Screening Berm and Landscape Plan
Figure 5: Site Infrastructure
Figure 6: Project Phases
Figure 7: Residences Located North of the Project Site

Exhibits (separate volumes)
Exhibit A: Detailed Site Plan, Sections, and Elevations
Exhibit B: Emergency Response Plan
Exhibit C: Traffic Impact Analysis
Exhibit D: Biological Site Assessment
Exhibit E: Cultural Resource Study
Exhibit F: Spill Prevention, Control and Countermeasure Plan
Exhibit G: Waste Management Plan
Exhibit H: Drainage Report

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Mesquite Solar Energy Project—SUP Application
1.0 Project Name and Location
1.1 Project Name
Mesquite Solar Energy Project, herein referred to as the “project” or “facility” in this Narrative Report.
1.2 Location
Figure 1 shows the location and boundaries of the project site. The project site comprises
approximately 3,800 acres located immediately south of Elliot Road (the 2,520-acre original site
located immediately east of the 411th Avenue alignment plus an 1,280-acre expansion area located
immediately west of the 411th Avenue alignment), southwest of Wintersburg, Maricopa County,
Arizona, approximately two miles west of the Mesquite Generating Station. The site includes Section
19 and portions of Sections 18 and 20 of Township 1 South, Range 6 West, and Sections 13, 14, and
15 and a portion of Section 24 of Township 1 South, Range 7 West, Gila and Salt River base and
meridian.
The site has been partially developed with the Mesquite Solar 1 facility and supporting civil and
electrical infrastructure, and it is otherwise currently vacant with the exceptions of (a) five
groundwater wells and an associated pipeline on the original site that supply water to the Mesquite
Generating Station and (b) El Paso Natural Gas pipelines that cross the southwest corner of the
expansion area. The Palo Verde Nuclear Generating Station, Arlington Valley Energy Facility, and
Mesquite Generating Station are located within two miles of the project site.

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Mesquite Solar Energy Project—SUP Application
2.0 Purpose of Request
2.1 Expansion of the Project Site
This request for an amendment of the Special Use Permit (SUP) is to add the 1,280-acre expansion
area to the project site, which will allow the more extensive development of a photovoltaic (PV) solar
energy generation facility. As on the 2,520-acre original site, the facility in the expansion area will
employ PV panels that absorb sunlight and directly produce electricity without use of heat transfer
fluid or cooling water. The applicant and owner of the expansion area is SEP II, LLC (herein referred
to as the “applicant”), an affiliate of Sempra U.S. Gas & Power. The facility will operate year-round,
producing electric power whenever the sun is shining. When fully developed on both the original site
and expansion area, the facility will produce up to 700 megawatts (MW) of clean solar power, which
would supply the energy needs of up to about 260,000 residences. Energy from the facility is and will
be sold to utilities in the wholesale market. The facility is planned to be developed at rate of 50 to 120
MW per year. The existing initial phase of the facility, known as Mesquite Solar 1, is located on the
original site. Mesquite Solar 1 produces up to 165 MW and was completed in December 2012.
2.2 Project Benefits
The economics of PV solar energy have improved dramatically over the past several years, making
solar energy an electricity source of choice. Solar energy offers the opportunity to protect the
environment by avoiding the production of greenhouse gases and other air emissions, decreasing our
dependence on fossil fuels, and reducing the need for construction of fossil fueled power plants.
Solar energy also benefits the economy generating jobs, business income, and tax revenue for
Maricopa County and Arizona. Because solar energy is produced when demand for electricity is at its
highest (during bright daylight hours), it helps to meet peak demand.
2.3 Site Suitability
Key to solar energy production is the availability and intensity of solar radiation. Arizona is
particularly well suited for solar energy, with more than 300 days per year of sunshine and relatively
intense solar radiation. As shown in Figure 2, the general area of the project is highly suitable for
solar energy production because it has some of the highest solar radiation levels in the United States.
Other important criteria for determining the location of a solar energy generation facility include
proximity to transmission facilities suitable for interconnection, land availability, flat terrain, and
compatible adjacent land uses. As described herein, both the original site and the expansion area
have all of these characteristics.

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Mesquite Solar Energy Project—SUP Application
3.0 Previous Approvals
3.1 CPA 200005 and SUP Z2000071 (Water Property)
Of the 2,520 acres comprising the original site, 1,943 acres were part of approximately 3,000 acres
acquired in 2001 for their groundwater rights needed to support operation of the Mesquite Generating
Station. Land management of this “water property” was originally subject to SUP Z2000071 but has
been transferred to CPA 200005. The transfer was made pursuant to an SUP amendment
(referenced as SUP Z2013049) and an associated CPA (referenced as CPA 2013004).
3.2 CPA 200807 and SUP Z2008066 (Original Site)
Of the 2,520 acres comprising the original site, 577 acres were acquired in 2007-08 that are
additional to the 1,943 acres of water property. In December 2008, the Maricopa County Board of
Supervisors approved (a) Comprehensive Plan Amendment (CPA) 200807, which designated the
planned land use of the original site as Industrial for solar energy generation facilities, and (b) SUP
Z2008066, which amended SUP Z2000071 by providing relief from the requirement to re-vegetate the
water property to the extent that solar energy generation facilities are developed. The stipulation
providing for such relief has been transferred to CPA 200005 pursuant to an SUP amendment
(referenced as SUP Z2013049) and an associated CPA (referenced as CPA 2013004), and reads as
follows:
If an SUP for any given portion of the water property is approved for use of that
portion for solar energy generation facilities, then upon start of construction of such
solar energy generation facilities, compliance with the Land Management Plan shall
not require any past, existing, or future re-vegetation of that portion except as
provided under said SUP, and instead the following land management conditions
shall take effect:
1. All re-vegetated areas within the given portion of the water property are permitted
to undergo vegetation removal as necessary for construction and operation of the
solar energy generation facilities.
2. Measures to protect Centennial Wash shall be implemented as provided in the
approved SUP for the solar energy generation facilities. These measures shall
include soil stabilization and drainage control features.
3. Measures to control noxious weeds shall be implemented as provided in the
approved SUP for the solar energy generation facilities.
4. Measures to control blowing dust and wind erosion shall be implemented as
provided in the approved SUP for the solar energy generation facilities.
3.3 SUP Z2009022 and Amendments (Original Site)
In January 2010, the Maricopa County Board of Supervisors approved SUP Z2009022, which
provided for the development of solar energy generation facilities on the 2,520-acre original
site. In February 2011, minor amendment Z2010073 was approved, reflecting a revised
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Mesquite Solar Energy Project—SUP Application
drainage design. In September 2012, minor amendment Z2012052 was approved, reflecting
addition of an administration building.
3.4 CPA 200910 (Expansion Area)
In December 2009, the Maricopa County Board of Supervisors approved CPA 200910, which
designated the planned land use of the expansion area as Industrial for solar energy
generation facilities.
3.5 Other Previous Approvals
The subject project of this SUP application is limited to the solar energy generation facility. Other
facilities associated with the project were the subject of other previous approvals.
An existing generation-tie power line that serves both the original site and the expansion area is
under the permitting jurisdiction of the Arizona Corporation Commission. The power line operates at
230 kilovolts (kV) and is approximately four miles long. The power line consists of two circuits
supported on a single set of tubular steel poles and extends from the 230 kV bus of the existing
substation located on the original site to the existing 230 kV switchyard located at the Mesquite
Generating Station. The power line route is shown on Figure 1. The Arizona Corporation
Commission approved the power line in October 2009, and in November 2011 the power line began
operation in conjunction with initial power generation by Mesquite Solar 1.
To accommodate interconnection of the power line, the Mesquite Generating Station 230 kV
switchyard was modified to add new switching devices and termination structures. This modification,
which was confined to the existing switchyard area and its immediate surroundings, was addressed in
a minor amendment of SUP Z2000071 governing the Mesquite Generating Station. The minor
amendment also addressed the portion of the new power line that is located on the site of the
Mesquite Generating Station.

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Mesquite Solar Energy Project—SUP Application
4.0 Facility Description
4.1 Overview
The solar energy generation facility employs PV panels that absorb sunlight and directly produce
electricity. The facility consists of (a) a solar field of PV panels mounted on steel structures, (b) an
electrical collection system that aggregates the output from the PV panels and converts the electricity
from direct current (DC) to alternating current (AC), (c) a substation where all of the facility output is
combined and transformed to a voltage of 230 kV, (d) civil infrastructure including driveways,
drainage channels, a screening berm, and fencing, and (e) an administration building. The substation
and administration building are located on the original site and will also serve the expansion area.
Figure 1 provides a plot plan of the site in the context of surrounding land uses, and Exhibit A
provides a detailed site plan, sections, and elevation drawings. Photograph 1 shows PV panels at the
Mesquite Solar 1 facility. The PV panels that will be installed on the balance of the original site and in
the expansion area will be similar in general appearance to the panels shown in the photograph.

Photograph 1: Solar Panels in an Array (Photograph from Mesquite Solar 1)
4.2 Solar Field
As on the original site, the solar field in the expansion area will consist of PV panels mounted on steel
support structures. The supports will be either fixed or pivoting, depending on the specific PV panel
manufacturer(s) selected. In either case, the assembled PV panels will have a typical height of about
6 feet and a maximum height of 8 feet. The PV panels will be arranged in rows with center-to-center
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Mesquite Solar Energy Project—SUP Application
spacing of 12 to 22 feet. In the case of fixed supports, the rows will be aligned east to west and the
PV panels will be tilted to the south. In the case of pivoting supports, the rows will be aligned north to
south and the PV panels will pivot, tracking the sun, east to west.
4.3 Electrical Collection System
As on the original site, the PV panels in the expansion area will be organized into electrical groups
referred to as “blocks.” Each block will encompass a minimum 6 acres of PV panels (producing at
least 1 MW) and will include one modular inverter enclosure. The size of each block will depend
upon the capacity of the inverters housed in the block’s associated inverter enclosure, which in turn
will depend upon the type and size of inverters available for purchase and other such electrical design
considerations.
Conductors, hung under the PV panels and extending underground, will feed the DC to AC inverters
and associated switchgear housed in each block’s inverter enclosure. Each inverter enclosure is
anticipated to be a 12-foot-by-34-foot pre-fabricated structure up to 15 feet in height and will be
unoccupied except during inspection and maintenance. Each inverter enclosure will have an
associated outdoor transformer to step up the electricity voltage from the inverter output level (e.g.,
480 V to 34.5 kV). From each such transformer, electricity will be conveyed via an underground
circuit to 34.5 kV switchgear housed in a modular collection enclosure that gathers the output of up to
30 MW of PV panels. Each collection enclosure is anticipated to be an 8-foot-by-60-foot pre-
fabricated structure up to 12 feet in height and cannot be occupied.
From each collection enclosure, electricity will be conveyed via an underground 34.5 kV collector
circuit to a common 34.5 kV bus within the existing substation located on the original site. Such
underground collector circuits originating in the expansion area will cross the 411th Avenue alignment
near the north and/or south boundaries of the expansion area.
4.4 Substation
Figure 3 shows a conceptual one-line diagram of the electrical collection system and substation. The
substation is a central hub for the 34.5 kV collector circuits and step ups the electricity voltage from
34.5 kV to 230 kV. The substation site is approximately 6 acres in size and includes, but is not limited
to, the following major components:
• 34.5 kV bus and associated switching devices
• 230 kV bus and associated switching devices
• 187 MVA, 34.5/230 kV transformers
• 34.5 kV capacitors
• Tubular steel support structures up to 40 feet in height
• Grounding grid
• Prefabricated modular control building (unoccupied except during inspection and maintenance)
• Perimeter fence
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