Gateway West Transmission Line Draft EIS 

Appendix B 

Transmission Line and Substation Components Common to All 

Action Alternatives 

This appendix contains detailed information provided by the Proponents regarding the 

components of the transmission system evaluated in the EIS, including the transmission 

structures, the communications system, and the substations. These component descriptions 

apply to the Proposed Route and Route Alternatives; throughout this appendix, a reference 

to a segment includes the Route Alternatives for that segment.
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-iii

Table of Contents

1. SYSTEM COMPONENTS................................................................................... B-1

1.1 Transmission Structures ..............................................................................B-1

1.1.1 Types of Transmission Line Support Structures ..............................B-1

1.1.2 Structure and Conductor Clearances.............................................B-10

1.1.3 Structure Foundations....................................................................B-10

1.2 Conductors.................................................................................................B-11

1.3 Other Hardware..........................................................................................B-12

1.3.1 Insulators .......................................................................................B-12

1.3.2 Grounding Systems........................................................................B-12

1.3.3 Minor Additional Hardware.............................................................B-14

1.4 Communication Systems............................................................................B-14

1.4.1 Optical Ground Wire.......................................................................B-14

1.4.2 Regeneration Stations....................................................................B-15

1.5 Access Roads ............................................................................................B-16

1.5 Substations ................................................................................................B-24

1.5.1 Substation Components.................................................................B-24

1.5.2 Distribution Supply Lines................................................................B-26

2 SYSTEM CONSTRUCTION.............................................................................. B-27

2.1 Land Requirements and Disturbance.........................................................B-27

2.1.1 Right-of-Way Width........................................................................B-27

2.1.2 Right-of-Way Acquisition................................................................B-27

2.1.3 Land Disturbance...........................................................................B-31

2.2 Transmission Line Construction.................................................................B-31

2.2.1 Transmission Line System Roads..................................................B-35

2.2.2 Soil Borings....................................................................................B-36

2.2.3 Staging Areas.................................................................................B-36

2.2.4 Site Preparation .............................................................................B-37

2.2.5 Install Structure Foundations .........................................................B-38

2.2.6 Erect Support Structures................................................................B-39

2.2.7 String Conductors, Shield Wire, and Fiber Optic Ground Wire ......B-39

2.2.8 Cleanup and Site Reclamation.......................................................B-41

2.3 Communication System .............................................................................B-42

2.3.1 Regeneration Stations....................................................................B-42

2.3.2 Access Road..................................................................................B-42

2.4 Substation Construction .............................................................................B-42

2.4.1 Substation Roads...........................................................................B-42

2.4.2 Soil Boring......................................................................................B-43

2.4.3 Clearing and Grading.....................................................................B-43

2.4.4 Storage and Staging Yards ............................................................B-43

2.4.5 Grounding ......................................................................................B-43

2.4.6 Fencing ..........................................................................................B-43

2.4.7 Foundation Installation...................................................................B-44

2.4.8 Oil Containment .............................................................................B-44
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Components Common to All Action Alternatives

B-iv

2.4.9 Structure and Equipment Installation .............................................B-44

2.4.10 Control Building Construction.........................................................B-45

2.4.11 Conductor Installation ....................................................................B-45

2.4.12 Conduit and Control Cable Installation...........................................B-45

2.4.13 Construction Cleanup and Landscaping ........................................B-45

2.5 Special Construction Techniques...............................................................B-45

2.5.1 Blasting ..........................................................................................B-45

2.5.2 Helicopter Use................................................................................B-47

2.5.3 Water Use ......................................................................................B-48

2.6 Construction Elements ...............................................................................B-50

2.6.1 Construction Workforce..................................................................B-50

2.6.2 Construction Equipment and Traffic...............................................B-51

2.6.3 Removal of Facilities and Waste Disposal .....................................B-59

2.6.4 Construction Schedule...................................................................B-61

3 SYSTEM OPERATIONS AND MAINTENANCE............................................... B-65

3.1 Routine System Operation and Maintenance.............................................B-65

3.1.1 Routine System Inspection, Maintenance, and Repair...................B-66

3.1.2 Transmission Line Maintenance.....................................................B-66

3.1.3 Hardware Maintenance and Repairs..............................................B-66

3.1.4 Access Road and Work Area Repair..............................................B-67

3.1.5 Vegetation Management ................................................................B-67

3.1.6 Substation and Regeneration Station Maintenance .......................B-71

3.2 Emergency Response................................................................................B-73

4 DECOMMISSIONING ....................................................................................... B-75
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-v

List of Tables

Table B-1. Proposed Structure Configuration...................................................................B-9

Table B-2. Foundation Excavation Dimensions..............................................................B-11

Table B-3. Proposed Regeneration Station Locations....................................................B-15

Table B-4. Typical Access Road Requirements for Transmission Line System.............. B-17

Table B-5. Summary of Land Required for Construction and Operations....................... B-28

Table B-6. Summary of Land Disturbance Resulting from Construction and 

Operations....................................................................................................B-32

Table B-7. Miles of New and Improved Access Roads1/ .................................................B-36

Table B-8. Construction Staging Areas and Helicopter Fly Yards ..................................B-37

Table B-9. Summary of Shallow Bedrock.......................................................................B-46

Table B-10. Estimated Water Usage by Component, Segment, and Activity.................... B-49

Table B-11. Transmission Line Construction Equipment Requirements – Segments 

1–4 ...............................................................................................................B-52

Table B-12. Transmission Line Construction Equipment Requirements – Segments 

5-10..............................................................................................................B-53

Table B-13. Substation Equipment Requirements – Segments 1–4.................................B-54

Table B-14. Substation Equipment Requirements – Segments 5–10............................... B-55

Table B-15. Average and Peak Construction Traffic ........................................................B-56

Table B-16. Solid Waste Generation from Construction Activities ....................................B-60

Table B-17. Construction Schedule..................................................................................B-62
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-vi

List of Figures

Figure B-1. Proposed Tangent Single-Circuit 230-kV H-Frame Structure..........................B-2

Figure B-2. Proposed Tangent Single-Circuit 500-kV Lattice Steel Structure ....................B-3

Figure B-3. Proposed Tangent Double-Circuit 500-kV Lattice Steel Structure...................B-4

Figure B-4. Proposed and Alternative Single-Circuit ROW Configurations ........................B-5

Figure B-5. Two-Circuit 500-kV ROW Configurations........................................................B-6

Figure B-6. Alternative Single-Circuit 500-kV Guyed “Delta” and “V” ROW 

Configuration..................................................................................................B-7

Figure B-7. 500-kV Structure Types Considered but not Carried Forward.........................B-8

Figure B-8. Typical Regeneration Station Site.................................................................B-16

Figure B-9. Typical Road Sections for Different Terrains.................................................B-19

Figure B-10. Access Road Dry Crossings .........................................................................B-20

Figure B-11. Access Road Wet Crossings ........................................................................B-21

Figure B-12. Typical 500-kV Substation ............................................................................B-25

Figure B-13. Transmission Line Construction Sequence...................................................B-35

Figure B-14. Conductor Installation...................................................................................B-40

Figure B-15. Total Projected Labor Force by EPC Analysis Area and Week ..................... B-51

Figure B-16. Live-line Maintenance Space Requirements, 230 kV....................................B-68

Figure B-17. Live-line Maintenance Space Requirements, Single-Circuit 500 kV.............. B-69

Figure B-18. Live-line Maintenance Space Requirements, Double-Circuit 500 kV............. B-70

Figure B-19. Right-of-Way Vegetation Management.........................................................B-72

Figure B-20. Right-of-Way Vegetation Management in Steep Terrain............................... B-73
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-1

This appendix contains detailed information provided by the Proponents regarding the 

components of the transmission system evaluated in the EIS, including the transmission 

structures, the communications system, and the substations. These component 

descriptions (Section 1.0) apply to the Proposed Route and Route Alternatives, and 

throughout this appendix, a reference to a segment includes the Route Alternatives for 

that segment. It provides details regarding construction of the system (Section 2.0), 

goes on to provide information regarding the operations and maintenance of the system 

(Section 3.0), and finally details the proposed abandonment and restoration techniques

(Section 4.0). 

1. SYSTEM COMPONENTS

This section describes the various components of the transmission system for the 

Gateway West Project, including the structures themselves, the conductors used, other 

hardware needed, the communication system, the access roads, and finally the 

substations. Both the proposed and alternative structures are described here, and 

details are provided to support the discussion of transmission structure alternatives 

found in Section 2.7 of Chapter 2 of the EIS. 

1.1 Transmission Structures

1.1.1 Types of Transmission Line Support Structures

The proposed transmission line circuits would typically be supported by three types of 

structures: steel H-frame 230-kV structures and self-supporting single- and doublecircuit 500-kV lattice steel towers1

. Figures B-1 through B-3 illustrate the typical tangent 

structure configurations, which would be the predominant types used for the Project. 

Tangent structures are designed to support the conductors where the line angle at the 

structure location is typically one degree or less, meaning the transmission line is 

essentially a straight line. Figures B-4 and B-5 illustrate the proposed and alternative 

ROW design configurations. Figure B-6 shows details for the guyed structure 

variations.

In addition to the more typical tangent structure configurations, specialized structures 

are designed where the line must turn an angle. Each structure type is individually 

designed, depending on the line angle and the underlying soil and rock conditions, to 

withstand the pull of the wires in different directions. Angle structures are heavier and 

have deeper foundations. Figure B-7 illustrates structure types considered during 

preliminary Project design but not carried forward as proposed by the Proponents. 

Table 2.6-2 and Section 2.6.2, Chapter 2, provide a comparison with proposed 

structures and a rationale for the selection of the proposed structures.

230-kV Steel H-Frame Structures 

The two proposed 230-kV single-circuit lines between the Windstar and Aeolus 

Substations (Segments 1E and 1W[a]) would use steel H-frame structures. The 

1 A 5.5-mile interconnecting 345-kV transmission line (Segment 3A) would be constructed between the proposed 

Anticline Substation yard and the existing Jim Bridger Substation 345-kV yard to electrically connect the two 

substations. The 230-kV circuit from Creston (Segment 3B) would leave the 230/500-kV line and continue for about 

4.3 miles to a termination at the Jim Bridger Substation in the 230-kV yard.
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-2

Figure B-1. Proposed Tangent Single-Circuit 230-kV H-Frame Structure
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-3

Figure B-2. Proposed Tangent Single-Circuit 500-kV Lattice Steel Structure

Detail of Conductor Bundle
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-4

Figure B-3. Proposed Tangent Double-Circuit 500-kV Lattice Steel Structure 
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-5

Figure B-4. Proposed and Alternative Single-Circuit ROW Configurations

500-kV Proposed 

Design

500-kV Alternative 

Design

230-kV Proposed 

Design
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-6

Figure B-5. Two-Circuit 500-kV ROW Configurations

Design Variation

Proposed Design

Structure Variation
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-7

Guyed “Delta

Guyed “V”

Figure B-6. Alternative Single-Circuit 500-kV Guyed “Delta” and “V” ROW 

Configuration
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-8

STRUCTURE

Figure B-7. 500-kV Structure Types Considered but not Carried Forward
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-9

structures that would be replaced when reconstructing the existing 230-kV line between 

the Dave Johnston and Aeolus Substations (Segment 1W[c]) would also use steel Hframe structures. 

The 230-kV steel H-frames would use self-weathering steel. Weathering steel is 

manufactured from a group of steel alloys that were developed to eliminate the need for 

painting or other protective finish. This type of steel alloy forms a stable rust-like 

appearance if exposed to the weather for several years. The average distance between 

H-frame structures would be approximately 700 feet. Typically, the 230-kV single-circuit 

H-frame structures would have pole lengths ranging between 70 and 100 feet. 

Embedment depths are typically 10 percent of the pole length plus 2 feet, which in the 

case of this Project is expected to range between 9 and 12 feet. The structure heights 

above ground vary from 60 to 90 feet.

500-kV Galvanized Lattice Steel Structures

Lattice steel towers would be fabricated with galvanized steel members treated to 

produce a dulled galvanized finish. The average distance between 500-kV towers 

would be 1,200 to 1,300 feet. Structure heights would vary depending on terrain and 

the requirement to maintain minimum conductor clearances from ground. The 500-kV 

single-circuit towers would vary in height from 145 to 180 feet and the double-circuit 

towers would vary in height from 160 to 190 feet. Table B-1 describes the approximate 

number and type of structures by segments, typical height, typical distances between 

structures, and temporary and permanent disturbance areas by structure.

Table B-1. Proposed Structure Configuration Segment Transmission Line Length (miles) Structure Type Typical Height (feet) No. of Structures1/ Average Distance 

Between Structures1/

(feet)Short TermDisturbance Area per structure (sq. feet.) Long TermDisturbance Area per structure (sq. feet.)

1E 100.6 230-kV HFrame Structure60–90 732 700 ROW Width 125 

feet x 150 feet = 

0.43 acre

ROW Width 50 

feet x 50 feet = 

0.06 acre

1W(a) 76.5 230-kV HFrame Structure60–90 588 700 ROW Width 125 

feet x 150 feet = 

0.43 acre

ROW Width 50 

feet x 50 feet = 

0.06 acre

1W(c) 70.6 230-kV HFrame Structure60–90 531 existing span 

lengths 

assumed to 

be 700

ROW Width 125 

feet x 150 feet = 

0.43 acre

ROW Width 50 

feet x 50 feet = 

0.06 acre

2 96.7 500-kV DoubleCircuit Lattice 

Tower

160–

190 

414 1,200–1,300 ROW Width 300 

feet x 250 feet = 

1.72 acres

ROW Width 50 

feet x 50 feet = 

0.06 acre

3 56.5 2/ 500-kV DoubleCircuit Lattice 

Tower

160–

190 

253 1,200–1,300 ROW Width 300 

feet x 250 feet = 

1.72 acres

ROW Width 50 

feet x 50 feet = 

0.06 acre

4 203.0 500-kV DoubleCircuit Lattice 

Tower

160–

190 

893 1,200–1,300 ROW Width 300 

feet x 250 feet = 

1.72 acres

ROW Width 50 

feet x 50 feet = 

0.06 acre
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-10

Table B-1. Proposed Structure Configuration (continued) Segment Transmission Line Length (miles) Structure Type Typical Height (feet) No. of Structures1/ Average Distance Between Structures1/ (feet)

Temporary Disturbance Area per structure (sq. feet.) Permanent Disturbance Area per structure (sq. feet.)

5 54.6 500-kV SingleCircuit Lattice 

Tower

145–

180 

245 1,200–1,300 ROW Width 250 

feet x 250 feet = 

1.72 acres

ROW Width 50 

feet x 50 feet = 

0.06 acre

6 0.5 500-kV SingleCircuit Lattice 

Tower

145–

180 

10 varies ROW Width 250 

feet x 250 feet = 

1.43 acres

ROW Width 50 

feet x 50 feet = 

0.06 acre

7 118.1 500-kV SingleCircuit Lattice 

Tower

145–

180 

534 1,200–1,300 ROW Width 250 

feet x 250 feet = 

1.43 acres

ROW Width 50 

feet x 50 feet = 

0.06 acre

8 131.0 500-kV SingleCircuit Lattice 

Tower

145–

180 

577 1,200–1,300 ROW Width 250 

feet x 250 feet = 

1.43 acres

ROW Width 50 

feet x 50 feet = 

0.06 acre

9 161.7 500-kV SingleCircuit Lattice 

Tower

145–

180 

707 1,200–1,300 ROW Width 250 

feet x 250 feet = 

1.43 acres

ROW Width 50 

feet x 50 feet = 

0.06 acre

10 33.6 500-kV SingleCircuit Lattice 

Tower

145–

180 

155 1,200–1,300 ROW Width 250 

feet x 250 feet = 

1.43 acres

ROW Width 50 

feet x 50 feet = 

0.06 acre

1/ Reasonable estimate from preliminary engineering. In infrequent locations where spans between structures would 

exceed 1,800 feet, the right-of-way may need to be increased to provide clearance from conductors blown toward 

the right-of-way edge.

2/ Includes 230-kV and 345-kV interconnections with existing Jim Bridger Substation, which will be constructed using 

tubular steel single-circuit structures. Note that for estimating purposes, the larger disturbance footprint of the 500-

kV double-circuit tower type was used. Actual disturbance will be less.

1.1.2 Structure and Conductor Clearances

Conductor phase-to-phase and phase-to-ground clearance parameters are determined 

in accordance with the NESC, ANSI C2, produced by the ANSI. This code provides for 

minimum distances between the conductors and ground, crossing points of other lines 

and the transmission support structure, and other conductors, and minimum working 

clearances for personnel during energized operation and maintenance activities (IEEE 

2007). Typically, the clearance of conductors above ground is 35 feet for 500 kV and 

28 feet for 230 kV. During detailed design, clearances may be increased to account for 

localized conditions.

1.1.3 Structure Foundations

The 500-kV single- and double-circuit lattice steel structures each require four 

foundations with one on each of the four corners of the lattice towers. The foundation 

diameter and depth would be determined during final design and are dependent on the 

type of soil or rock present at each specific site. Typically, the foundations for the 

single-circuit tangent lattice towers would be composed of steel-reinforced concrete 

drilled piers with a typical diameter of 4 feet and a depth of approximately 15 feet. For 

the double-circuit tangent lattice towers, typical foundation dimensions would be 6 feet 
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-11

in diameter and 20 feet in depth. Typical foundation diameters and depths for the 

single- and double-circuit structure families are shown in Table B-2.

Table B-2. Foundation Excavation Dimensions

Structure 

No. of 

Holes 

Depth 

(feet)

Diameter 

(feet)

Concrete 

(cubic 

yards)

500-kV Single Circuit - Tangent Lattice Tower 4 22.0 4 41

500-kV Single Circuit - Small Angle Lattice Tower 4 24.5 4 46

500-kV Single Circuit - Medium Angle Lattice Tower 4 27.0 4 50

500-kV Single Circuit - Medium Dead-End Lattice Tower1/ 4 29.5 5 86

500-kV Single Circuit - Heavy Dead-End Lattice Tower 4 32.0 5 93

500-kV Double Circuit - Tangent Lattice Tower 4 26.0 5 76

500-kV Double Circuit - Small Angle Lattice Tower 4 28.5 5 83

500-kV Double Circuit - Medium Angle Lattice Tower 4 31.0 5 90

500-kV Double Circuit - Medium Dead-End Lattice Tower 4 33.5 6 140

500-kV Double Circuit - Heavy Dead-End Lattice Tower 4 36.0 6 151

1/ “Dead-end structure” typically refers to a structure that is placed at a point where the transmission line turns 

direction.

The 230-kV single-circuit H-frame structures are directly embedded into the ground and 

do not require concrete foundations. The embedment depth is typically 10 percent of 

the pole length plus 2 feet, which for the Project is expected to be between 9 and 12 

feet based on the structure heights proposed for the Project. The diameter of the hole 

excavated for embedment is typically the pole diameter plus 18 inches. When a pole is 

placed in a hole, native or select backfill would be used to fill the voids around the 

perimeter of the hole.

1.2 Conductors

The proposed conductor for the 500-kV lines is 1,949.6 kcmil2 42/7 ACSR/TWD, 

“Athabaska/TW”3

. Each phase of a 500-kV three-phase circuit4 would be composed of 

three subconductors in a triple bundle configuration. The individual 1,949.6 kcmil 

conductors would be bundled in a triangular configuration with spacing of 18 and 25 

inches between subconductors (see Figures B-2 and B-3). The triple-bundled 

configuration is proposed to provide adequate current carrying capacity and to provide 

for a reduction in audible noise and radio interference as compared to a single largediameter conductor. Each 500-kV subconductor would have a 42/7 aluminum/steel 

stranding, with an overall conductor diameter of 1.504 inches and a weight of 2.199 

pounds per foot and a non-specular finish5

.

At 500 kV, where multiple conductors are utilized in a bundle for each phase, the bundle 

spacing would be maintained through the use of conductor spacers at intermediate 

2 Kcmil (1000 cmils) is a quantity of measure for the size of a conductor; kcmil wire size is the equivalent crosssectional area in thousands of circular mils. A circular mil (cmil) is the area of a circle with a diameter of one 

thousandth (0.001) of an inch. 3 Aluminum/steel refers to the conductor material composition. The preceding numbers indicate the number of 

strands of each material type present in the conductor (i.e., 42/7 aluminum/steel stranding has 42 aluminum strands 

wound around 7 steel strands). 4 For transmission lines, a circuit consists of three phases. A phase may consist of one conductor or multiple 

conductors (i.e., subconductors) bundled together.

5 Non-specular finish refers to a “dull” finish rather than a “shiny” finish.
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-12

points along the conductor bundle between each structure. The spacers serve a dual 

purpose: in addition to maintaining the correct bundle configuration and spacing, the 

spacers are also designed to damp out wind-induced vibration in the conductors. The 

number of spacers required in each span between towers would be determined during 

the final design of the transmission line.

The proposed conductor for the new 230-kV lines and for reconstructing of the portion 

of the existing Dave Johnston – Rock Springs 230-kV line between the Dave Johnston 

Power Plant and planned Aeolus Substation is 1,272 kcmil 45/7 ACSR “Bittern.” Each 

phase of a 230-kV three-phase circuit would be composed of two subconductors in a 

double-bundle configuration. The individual 1,272 kcmil conductors would be bundled 

in a vertical configuration with a spacing of 18 inches. The double-bundle configuration 

is proposed to provide adequate current carrying capacity and to provide for a reduction 

in audible noise and radio interference when compared to a single large-diameter 

conductor. Each 230-kV conductor would have 45/7 aluminum/steel stranding, with an 

overall conductor diameter of 1.345 inches and a weight of 1.432 pounds per foot and a 

non-specular finish.

Where multiple conductors are utilized in a bundle for each phase, the bundle spacing 

would be maintained through the use of conductor spacers at intermediate points along 

the conductor bundle between each structure. The spacers serve a dual purpose: in 

addition to maintaining the correct bundle configuration and spacing, the spacers are 

also designed to damp out wind-induced vibration in the conductors. The number of 

spacers required in each span between towers would be determined during the final 

design of the transmission line. 

1.3 Other Hardware

1.3.1 Insulators

As shown in Figure B-1, insulator assemblies for 230-kV H-frame tangent structures 

would consist of one insulator string hung vertically from the cross arm in the form of an 

“I.” As shown in Figures B-2 and B-3, insulator assemblies for 500-kV tangent 

structures would consist of two strings of insulators normally in the form of a “V.” These 

strings are used to suspend each conductor bundle (phase) from the structure, 

maintaining the appropriate electrical clearance between the conductors, the ground, 

and the structure. The V-shaped configuration of the 500-kV insulators also restrains 

the conductor so that it would not swing into the structure in high winds. Dead-end 

insulator assemblies for both 230-kV and 500-kV lines would use an I-shaped 

configuration, which consists of insulators connected horizontally from either a tower 

dead-end arm or a dead-end pole in the form of an “I.” Insulators would be composed 

of grey porcelain or green-tinted toughened glass or single unit polymer (no ceramic 

insulators).

1.3.2 Grounding Systems

AC transmission lines such as the Gateway West transmission lines have the potential 

to induce currents on adjacent metallic structures such as transmission lines, railroads, 

pipelines, fences, or structures that are parallel to, cross, or are adjacent to the 

transmission line. Induced currents on these facilities would occur to some degree 
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-13

during steady-state operating conditions and during a fault condition on the powerline. 

For example, during a lightning strike on the line, the insulators may flash over, causing 

a fault condition on the line and current would flow down the structure through the 

grounding system (i.e., ground rod or counterpoise) and into the ground. The 

magnitude of the effects of the AC induced currents on adjacent facilities is highly 

dependent on the magnitude of the current flows in the transmission line, the proximity 

of the adjacent facility to the line, and the distance (length) for which the two facilities 

parallel one another in proximity.

The methods and equipment needed to mitigate these conditions would be determined 

through electrical studies of the specific situation. As standard practice and as part of 

the design of the Project, electrical equipment and fencing at the substation would be 

grounded. All fences, metal gates, pipelines, metal buildings, and other metal 

structures adjacent to the ROW that cross or are within the transmission line ROW 

would be grounded. If applicable, grounding of metallic objects outside of the ROW 

may also occur, depending on the distance from the transmission line as determined 

through the electrical studies. These actions take care of the majority of induced 

current effects on metallic facilities adjacent to the line by shunting the induced currents 

to ground through ground rods, ground mats, and other grounding systems, thus 

reducing the effect that a person may experience when touching a metallic object near 

the line (i.e., reduce electric shock potential). In the case of a longer parallel facility, 

such as a pipeline parallel to the Project over many miles, additional electrical studies 

would be undertaken to identify any additional mitigation measures (more than the 

standard grounding practices) that would need to be implemented to prevent damaging 

currents from flowing onto the parallel facility, and to prevent electrical shock to a 

person that may come in contact with the parallel facility. Some of the typical measures 

that could be considered for implementation, depending on the degree of mitigation 

needed, could include (NACE International 2003):

• Fault Shields – shallow grounding conductors connected to the affected structure 

adjacent to overhead electrical transmission towers, poles, substations, etc. They 

are intended to provide localized protection to the structure and pipeline coating 

during a fault event from a nearby electric transmission power system.

• Lumped Grounding – localized conductor or conductors connected to the 

affected structure at strategic locations (e.g., at discontinuities). They are 

intended to protect the structure from both steady-state and fault AC conditions.

• Gradient Control Wires – a continuous and long grounding conductor or 

conductors installed horizontally and parallel to a structure (e.g., pipeline section) 

at strategic lengths and connected at regular intervals. These are intended to 

provide protection to the structure and pipeline coating during steady-state and 

fault AC conditions from nearby electric transmission power systems.

• Gradient Control Mats – typically used for aboveground components of a 

pipeline system, these are buried ground mats bonded to the structure, and are 

used to reduce electrical step and touch voltages in areas where people may 

come in contact with a structure subject to hazardous potentials. Permanent mats 

bonded to the structure may be used at valves, metallic vents, cathodic protection 

test stations, and other aboveground metallic and nonmetallic appurtenances 
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-14

where electrical contact with the affected structure is possible. In these cases 

there is no “standard” solution that would solve these issues every time. Instead, 

each case must be studied to determine the magnitude of the induced currents 

and the most appropriate mitigation given the ground resistivity, distance 

paralleled, steady-state and fault currents, fault clearing times expected on the 

transmission line, and distance between the line and the pipeline, to name a few 

of the parameters. If the electrical studies indicate a need to install cathodic 

protection devices on a parallel pipeline facility, a distribution supply line 

interconnection may be needed to provide power to the cathodic protection 

equipment.

During final design of the transmission line segments, appropriate electrical studies 

would be conducted to identify the issues associated with paralleling other facilities and 

the types of equipment that would need to be installed (if any) to mitigate the effects of 

the induced currents.

1.3.3 Minor Additional Hardware

In addition to the conductors, insulators, and overhead shield wires, other associated 

hardware would be installed on the tower as part of the insulator assembly to support 

the conductors and shield wires. This hardware would include clamps, shackles, links, 

plates, and various other pieces composed of galvanized steel and aluminum.

A grounding system would be installed at the base of each transmission structure that 

would consist of copper ground rods embedded into the ground in immediate proximity 

to the structure foundation and connected to the structure by a buried copper lead. 

When the resistance to ground for each transmission structure would be greater than 

25 ohms with the use of ground rods, counterpoise would be installed to lower the 

resistance with the intent to achieve 25 ohms or less. Counterpoise consists of a bare 

copper-clad or galvanized-steel cable buried a minimum of 12 inches deep, extending 

from structures (from one or more legs of structure) for approximately 200 feet within 

the ROW.

Other hardware that is not associated with the transmission of electricity may be 

installed as part of the Project. This hardware may include aerial marker spheres or 

aircraft warning lighting as required for the conductors or structures per FAA 

regulations.6 Structure proximity to airports and structure height are the determinants of 

whether FAA regulations would apply based on an assessment of wire/tower strike risk. 

The Proponents do not anticipate that structure lighting would be required because 

proposed structures would be less than 200 feet tall and would not be near airports that 

require structure lighting. 

1.4 Communication Systems

1.4.1 Optical Ground Wire

Reliable and secure communications for system control and monitoring of Gateway 

West is very important to maintain the operational integrity of the Project and of the 

6 U.S. Department of Transportation, Federal Aviation Administration, Advisory Circular AC 70/7460-1K Obstruction 

Marking and Lighting, August 1, 2000; and Advisory Circular AC 70/7460-2K Proposed Construction or Alteration of 

Objects that May Affect the Navigable Airspace, March 1, 2000.
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-15

overall interconnected system. Primary communications for relaying and control would 

be provided via the OPGW that would be installed on the transmission lines. For the 

500-kV transmission lines, a secondary communications path would be provided by the 

Proponents’ existing microwave system, which is currently installed from the Central 

Wyoming area near the Windstar Substation west to existing substations near Boise, 

Idaho. A secondary communication path may also be developed using a powerline 

carrier. No new microwave sites are anticipated for the Project. Updated microwave 

equipment may be installed at existing sites and at the substations.

Each structure would have two lightning protection shield wires installed on the peaks of 

each of the 500-kV single- or double-circuit lattice steel structures (see Figures B-2 and 

B-3). On the 230-kV H-frame structures (see Figure B-1) these lightning protection 

shield wires would be installed near the top of each pole. On both the 500-kV and 230-

kV lines where communication is required, one of the shield wires would be composed 

of extra high strength steel wire with a diameter of 0.495 inch and a weight of 0.517 

pound per foot. The second shield wire would be an OPGW constructed of aluminum 

and steel, which carries 48 glass fibers within its core. On the 500-kV lines, the OPGW 

would have a diameter of 0.637 inch and a weight of 0.375 pound per foot; on the 230-

kV lines, the OPGW would have a diameter of 0.465 inch. The glass fibers inside the 

OPGW shield wire would provide optical data transfer capability among the Proponents’ 

facilities along the fiber path. The data transferred are required for system control and 

monitoring. On lines where communication is not required, both of the shield wires 

would be composed of extra high strength steel wires with a diameter of 0.495 inch and 

a weight of 0.517 pound per foot For the Gateway Project, all 500-kV line segments 

would be designed to carry an OPGW. For the 230-kV lines, Segments 1W(a) and 1E 

would be designed to carry an OPGW, although the OPGW shield wire on Segment 1E 

would not immediately be connected to the communication system and would be left 

dark. Between the new Anticline Substation and the existing Jim Bridger Substation,

two communication paths (underground or aerial) would be required for redundancy. 

1.4.2 Regeneration Stations

As the data signal is passed through the optical fiber cable, the signal degrades with 

distance. Consequently, signal regeneration stations are required to amplify the signals 

if the distance between substations or regeneration stations exceeds 55 miles. As 

summarized in Table B-3, a total of 11 regeneration stations would be required.

Table B-3. Proposed Regeneration Station Locations

Segment Number

Total Construction 

Acres

Total Operations 

Acres

Segment 1W(a) – Windstar to Aeolus 1 1 0.5

Segment 2 – Aeolus to Creston 1 1 0.5

Segment 4 – Anticline to Populus 3 3 1.5

Segment 7 – Populus to Cedar Hill 2 2 1

Segment 8 – Midpoint to Hemingway 2 2 1

Segment 9 – Cedar Hill to Hemingway 2 2 1
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-16

A regeneration station may be housed within a substation control house in those cases 

where a substation is located along or near the final transmission route at an 

appropriate milepost; otherwise, land must be obtained or additional area requested. 

Where a new site is required, the typical site would be 100 feet by 100 feet, with a 

fenced area of 75 feet by 75 feet. A 12-foot- by 32-foot- by 9-foot-tall building or 

equipment shelter (metal or concrete) would be placed on the site, and access roads to 

the site and power from the local electric distribution circuits would be required. An 

emergency generator with a liquid petroleum gas fuel tank would be installed at the site 

inside the fenced area. Two diverse cable routes (aerial and/or buried) from the 

transmission ROW to the equipment shelter would be required. For Segment 1E, no 

electronics would be connected to the dark fiber; therefore, no regeneration station 

would be constructed as part of the Project. Figure B-8 illustrates the plan arrangement 

of a typical regeneration station.

Figure B-8. Typical Regeneration Station Site

1.5 Access Roads

Access and service roads are an essential part of the construction and operation of the 

Gateway West transmission line. Large foundation auger equipment, heavily loaded 
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-17

trucks, cranes, and specialized line construction equipment will be required for 

construction, maintenance, and emergency restoration activities. Annual ground based 

inspections require vehicular access using 4x4 trucks or 4x4 all-terrain vehicles (ATVs)

to each structure site. Section 3 of this appendix describes in detail operational 

requirements.

During construction vehicular access will be require to each structure. New access 

roads will be constructed and existing roads widened as needed to provide a 14-footwide travel way. Roads not required for operations will be restored to their original 

condition or left as is, depending on landowner/land management agency requirements. 

During routine operations, vehicular access will be needed to reach each structure for 

periodic inspections and maintenance and to areas of forest or tall shrubs to control 

vegetation in the ROW for safe operation. The Proponents plan to employ live-line 

maintenance techniques on the transmission line (see Appendix B, Section 3.1.3). Live 

line maintenance and repair techniques require the utilization of high-reach bucket trucks 

and other trucks and equipment. Roads required as routine service roads for the 

operational life of the Project will be revegetated following construction but will not be 

recontoured; they would be maintained free of trees and shrubs for a minimum 8-foot 

width.

In an emergency (i.e., in the event of a tower or conductor failure) full emergency 

access, including cranes and other heavy equipment, will be needed. Based on 

historical reliability of lattice structures and conductors, it is anticipated that only a small 

fraction of the tower sites will require emergency access over the life of the Project. 

For the purposes of calculating ground disturbance and operational needs, the Project 

has classified access roads into four categories—three of them permanent roads and 

one of them temporary. Table B-4 summarizes the four categories of roads needed for 

accessing the transmission line structures for the Project.

Table B-4. Typical Access Road Requirements for Transmission Line System

Road Type Construction Use Routine Operations Use 

Non-Routine 

Operations Use

Existing roads 

requiring no 

improvement

No change No change No change

Existing roads 

requiring 

improvement 

Unsurfaced 14-foot-wide 

straight sections of road 

and 16- to 20-foot-wide 

sections at corners

For routine activities, an 8-

foot portion of the road 

would be used and vehicles 

would drive over the 

vegetation (“two-track”).

For non-routine 

maintenance requiring 

access by larger vehicles, 

the full width of the access 

road may be used. Access 

roads would be repaired, as 

necessary, but would not be 

routinely graded. In order to 

preserve the ability to enter 

rapidly, the road structure 

(cuts and fills) would be left 

in place. 

New (service) 

roads

Unsurfaced 14-foot-wide 

straight sections of road 

and 16- to 20-foot-wide 

sections at corners

For routine activities, an 8-

foot portion of the road 

would be used and vehicles 

would drive over the 

vegetation (“two-track”).

Temporary 

roads 

Unsurfaced 14-foot-wide 

straight sections of road 

and 16- to 20-foot-wide 

sections at corners

None—contours would be 

restored, and the road 

would be ripped and 

seeded.

None
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-18

The largest of the heavy equipment needed, which dictates the minimum needed road 

dimensions, is a truck-mounted aerial lift crane, 100,000 pounds gross vehicle weight, 

8x8 drive, 210-foot telescoped boom. Vehicle width is 8’6” (102 inches) or less and 

wheelbase is around 25 feet. To accommodate this equipment, the road specifications 

require a 14-foot-wide road top (travel way) and 16- to 20-foot-wide road width in turns. 

The required road disturbance area and travel way in areas of rolling to hilly terrain will 

require a wider disturbance to account for cuts and fills, or where vehicles are required 

to pass one another while traveling in opposite directions. In addition, the Proponents 

plan to conduct maintenance using live-line maintenance techniques, thereby avoiding 

an outage to the critical transmission line infrastructure. High-reach bucket trucks along 

with other equipment would be used to conduct these activities. 

Access road construction employs heavy equipment including bulldozers, front-end 

loaders, dump trucks, backhoes, excavators, both tracked and rubber-tired, and 

graders. Other specialized equipment, including boom trucks to install culverts in some 

areas, will be used where needed. Roads will be built to provide a stable, permanent 

14-foot-wide travel surface. Depending on the side slope, this can include cuts and fills, 

crowning and ditching, at-grade water bars, and various kinds of waterbody crossings. 

Figure B-9 shows the typical cross-sections created during construction of this kind of 

road. Construction of new access roads would begin with vegetation removal. 

Merchantable timber would be cut and yarded to landings where the logs can be loaded 

on to trucks and hauled to market. Non-merchantable logs would be stored along the 

edge of the ROW for later use in site restoration. Smaller vegetation would be lopped 

and scattered outside the road prism. Topsoil would be stripped in from the road prism 

as required by federal land management agencies or landowners. Topsoil would be 

stored adjacent to the road or in a nearby workspace. Appropriate erosion control 

devices would be installed to prevent erosion or loss of the topsoil, including but not 

limited to tackifiers to prevent wind erosion and fugitive dust and silt fencing to prevent 

sediment runoff. As needed, the construction pad and access road would be graded to 

allow for safe access and construction. The grading may include cut and fill as needed 

to achieve a workable safe surface. 

Waterbody Crossings with Access Roads: Access roads would be constructed to 

minimize disruption of natural drainage patterns. Estimates of relative frequencies of 

crossing types and disturbance estimates for each are based on local engineering 

experience in Wyoming and Idaho (Raugutt 2010; Adams 2010). Each crossing will be 

designed with the roads as advanced engineering is completed, and crossing 

disturbance will vary. However, these estimates are conservative and consistent across 

all alternatives. On all federally managed lands, the Proponents would consult with the 

managing agency regarding relevant standards and guidelines pertaining to road 

crossing methods at waterbodies. Consultation would include site assessment, design, 

installation, maintenance, and decommissioning. Three types of waterbody crossings 

as well as avoidance are considered as part of the Project (see Figures B-10 and B-11). 

They are:

• Type 1—Drive through: Crossing of a channel with only minimal vegetation 

removal and no cut or fill needed. This is typical for much of the low-precipitation 

sagebrush country with rolling topography and streams that rarely flow with water. 
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-19

Figure B-9. Typical Road Sections for Different Terrains

Gateway West

Transmission Line Project

Idaho, Wyoming, Nevada 
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-20

Figure B-10. Access Road Dry Crossings

Gateway West

Transmission Line Project

Idaho, Wyoming, Nevada 
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-21

Figure B-11. Access Road Wet Crossings

Gateway West

Transmission Line Project

Idaho, Wyoming, Nevada 
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-22

• Type 2—Ford: Crossing of a channel that includes grading and stabilization. 

Stream banks and approaches would be graded to allow vehicle passage and 

stabilized with rock or other erosion control devices. The stream bed would in 

some areas be reinforced with coarse rock material, where approved by the landmanagement agency, to support vehicle loads, prevent erosion and minimize 

sedimentation into the waterway. The rock would be installed in the stream bed 

such that it would not raise the level of the streambed, thus allowing continued 

movement of water, fish and debris. A ford crossing results in an average 

disturbance profile of 25 feet wide (along the waterbody) and 50 feet long (along 

the roadway) for 1,000 square feet or 0.02 acre at each crossing. Disturbance 

amount is estimated based on need to get equipment into the riparian area to 

build the 14-foot-wide travelway and protect it from erosion by adding armoring. 

• Type 3—Culvert: Crossing of a waterbody that includes installation of a culvert 

and a stable road surface established over the culvert for vehicle passage. 

Culverts would be designed and installed under the guidance of a qualified 

engineer who, in collaboration with a hydrologist and aquatic biologist where 

required by the land management agency, would recommend placement 

locations; culvert gradient, height, and sizing; and proper construction methods. 

Culvert design would consider bedload and debris size and volume. The 

disturbance footprint for culvert installation is estimated to be 50 feet wide (along 

the waterbody) and 150 feet long (along the road) for 7,500 square feet or 0.17 

acre at each crossing. Ground-disturbing activities would comply with Agencyapproved BMPs. Construction would occur during periods of low water or normal 

flow. The use of equipment in streams would be minimized. All culverts would be 

designed and installed to meet desired riparian conditions, as identified in 

applicable unit management plans. Culvert slope would not exceed stream 

gradient. Typically, culverts would be partially buried in the streambed to maintain 

streambed material in the culvert. Sandbags or other non-erosive material would 

be placed around the culverts to prevent scour or water flow around the culvert. 

Adjacent sediment control structures such as silt fences, check dams, rock 

armoring, or riprap may be necessary to prevent erosion or sedimentation. 

Stream banks and approaches may be stabilized with rock or other erosion control 

devices. Culverts would be inspected and maintained annually for the life of the 

Project (estimated at 50 years or longer) for proper operation and to protect water 

quality.

• Avoid Crossing: Where constructing a new waterbody crossing is impractical or 

would require a bridge or a very large (>48-inch-diameter) culvert, existing 

waterbody crossings would be used and access redesigned to avoid a new 

crossing. All canals and ditches would be avoided by using existing crossings, as 

would all large perennial bodies like rivers. 

The performance of low water stream crossings would be monitored for the life of the 

access road, and maintained or repaired as necessary to protect water quality. 

Wetlands Crossings with Access Roads: During construction and for routine and 

emergency operations, access across wetlands to each structure location is necessary. 

The Proponents evaluated various method of minimizing impact to wetlands but do not 
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Components Common to All Action Alternatives

B-23

propose to utilize these alternatives, in lieu of permanent above grade fill, because they 

do not provide expeditious year around access to each structure site:

• Constructing at-grade roads with geotextiles and road materials which allow for 

water through-flow. This type of road would be below water during certain times 

of the year which would make locating the roads difficult, and the depth of the 

water over the drivable surface may make travel over the submerged road 

surface impractical or not feasible.

• Limiting structure access across wetlands to dry or frozen conditions along with 

the use low ground pressure tires or specialized tracked vehicles. This approach 

does not allow sufficient flexibility for emergency restoration and for operation 

and maintenance as the depth of water and/or soil conditions would not allow 

access to the structures during certain times of the year.

• Installing temporary matting materials to allow access for heavy vehicles and 

equipment. The mats typically come in the form of heavy timbers bolted 

together. Mats spread the concentrated axle loads from equipment over a much 

larger surface area thereby reducing the bearing pressure on fragile soils. 

However, mats are not effective when standing water is present. Matting has a 

limited service life before replacement is required and must be stored for 

maintenance and emergency restoration activities. While matting is sometimes 

used during construction, the Proponents report that they do not consider it a 

suitable alternative for emergency restoration or for periodic operations and 

maintenance activities. 

• Constructing ice roads if suitable winter conditions are present. Construction of 

ice roads in wetlands involves using lightweight equipment such as snowmobiles 

to tamp down existing snow cover and vegetation to allow penetration of frost 

into the wetland soils. This operation is followed by packing with heavier tracked 

equipment such as Bombardiers or wide tracked dozers. There is a relatively 

small window of time during the year where cold enough weather is present on to 

allow for this technique thereby restricting the flexibility required for operation and 

maintenance in other seasons besides winter.

• Constructing using helicopters in wetlands. The lighter single-circuit 500kV 

towers will be designed such that they can be erected by helicopter if needed. 

However, the weight of the double-circuit 500kV towers preclude the use of 

helicopter erection as explained in Section 2.5.2 of Appendix B. However, in 

each case, the use of ground based vehicles would still be required and would 

not eliminate the need for an access road to each structure to complete 

construction or during inspections and live-line maintenance activities.

The Proponents propose to utilize permanent fill to construct above-grade access roads 

in wetlands such that the travel surface would be higher in elevation than the ordinary 

high water level. The construction of above-grade access roads allows for the use of 

the types equipment described above and the most flexibility for construction operation, 

maintenance, and expedited access for emergency restoration throughout the year.

All waterbody and wetland disturbances would be completed under the terms of a 

USACE CWA Section 404 permit, the NPDES Construction Stormwater Permit (CWA 
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-24

402), and State 401 water quality certification requirements that govern activities within 

any waters of the United States. In Idaho, there is an additional requirement for a 

stream channel alteration permit for activities in stream beds. See also Appendix C-6 

for the Proponent’s mitigation framework.

1.5 Substations

The Project includes three proposed substations and expansions at one planned and 

eight existing substations.

1.5.1 Substation Components

The following sections describe key components of substations.

1.5.1.1 Bay

A substation “bay” is the physical location within a substation fenced area where the 

high-voltage circuit breakers and associated steel transmission line termination 

structures, high-voltage switches, bus supports, controls, and other equipment are

installed. For each transmission line, 500-kV, 345-kV, and 230-kV circuit breakers, 

high-voltage switches, bus supports, and transmission line termination structures would 

typically be installed. The 500-kV transmission line termination structures are 

approximately 125 to 135 feet tall. Additional equipment including 500/230-kV or 

500/345-kV transformers and 500-kV shunt reactors (which resemble a transformer in 

appearance), and 230-kV shunt capacitor banks would be installed. 

The appearance of the new and expanded substations would be similar to the 

appearance of the existing substations. The tallest structures in the substations would 

be the 500-kV, 345-kV, and 230-kV dead-end structures, which vary in height from 

approximately 70 feet (230 kV) to 125 to 135 feet (500 kV), and/or a microwave antenna 

tower, which would be in the range of 100 feet or more, depending on the height 

needed to maintain line of sight to the nearest microwave relay site. Figure B-12

includes a perspective sketch and an elevation view illustrating the appearance of a 

typical 500-kV substation with multiple line connections. 

1.5.1.2 Access Road

Permanent all-weather access roads are required at substation sites to provide access 

for personnel, material deliveries, vehicles, trucks, heavy equipment, low-boy tractor 

trailer rigs (used for moving large transformers), and ongoing maintenance activities at 

each site. Substation access roads are normally well-compacted, graded gravel roads 

approximately 20 feet in width with a minimum 110-foot turning radius to accommodate 

the delivery of large transformers to the site. New access roads of less than 1 mile 

would be developed from public roads to the Creston and Anticline Substations. Access 

to the Aeolus Substation would require an upgrade of a portion of CR 121. Access 

roads would exist at the time of Gateway West construction for all other substation 

locations. 
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-25

Figure B-12. Typical 500-kV Substation

1.5.1.3 Control Building

One or more control buildings are required at each substation to house protective 

relays, control devices, battery banks for primary control power, and remote monitoring 

equipment. The size and construction of the building depends on individual substation 

requirements. Typically, the control building would be constructed of concrete block, 

pre-engineered metal sheathed, or composite surfaced materials. Special control 

buildings may be developed within the substation developments to house other control 

and protection equipment. For example, at Aeolus a static var compensation (SVC) 

building would be developed to protect power electronic equipment, controls, and 

cooling equipment. 

1.5.1.4 Fencing and Landscaping

Security fencing would be installed around the entire perimeter of each new or 

expanded substation to protect sensitive equipment and prevent accidental contact with 

energized conductors by third parties. This 7-foot-high fence would be constructed of 

chain link with steel posts, with one foot of barbed wire above the chain link, and with 

locked gates. If required by the landowner or permitting agency, landscaping would be 

established using drought-resistant vegetation where allowed. 
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-26

1.5.2 Distribution Supply Lines

Station service power would be required at each substation or regeneration station. 

Typically, station service power is provided from a local electric distribution line, located 

in proximity to the substation or regeneration station. The voltage of the distribution 

supply line is typically 34.5 kV or lower and carried on wood poles. For all new sites, it 

would be necessary to extend the electric distribution line from a suitable take-off point 

on the existing distribution line to the new Gateway West substation site. The location 

and routing of the existing distribution lines to the new substation sites would be 

determined during the final design process. For Gateway West, new distribution line 

extensions to provide station service power are anticipated for the Creston, Anticline, 

and Cedar Hill Substations. The distance between existing distribution supply and the 

substations ranges from 200 feet to 3.3 miles. The remaining substation locations 

would exist at the time of the construction of Gateway West and new distribution line 

extensions to provide station service power would not be required. However, 

modifications to the existing distribution facilities may be necessary to provide increased 

capacity to support the expansions at the existing substation sites.
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-27

2 SYSTEM CONSTRUCTION

The following section and subsections detail construction activities for the Project, 

including transmission line, substation communication, and associated ancillary features.

2.1 Land Requirements and Disturbance

2.1.1 Right-of-Way Width 

The Proponents propose to acquire a permanent 300-foot-wide ROW for construction 

and operation of the 500-kV double-circuit sections of the Project, a 250-foot-wide ROW 

for the 500-kV single-circuit sections of the Project, and a 125-foot-wide ROW for the 

230-kV single-circuit sections of the Project. The Design Variation under which two 

single-circuit self-supporting 500-kV structures would be installed would require 350 feet 

of ROW. The Structure Variation using alternative 500-kV guyed “Delta” structures in a 

side-by-side configuration would require 375 feet of ROW. However, in the isolated 

situation where spans between structures would exceed 1,800 feet as compared to the 

average span of 1,200 to 1,300 feet, the ROW width may need to be increased to 

provide appropriate clearance from conductors blown toward the ROW edge, and a 

parallel circuit separation distance of greater than 175 feet would be required for 

protection in the unlikely event of a tower tipping into an adjacent line. Longitudinal 

offsets of tall towers may also be required. Figures B-4 through B-6 illustrate the ROW 

width requirements. The determination of these widths is based on two criteria: 

• Sufficient clearance must be maintained during a high wind event when the 

conductors are blown towards the ROW edge.

• Sufficient room must be provided within the ROW to perform transmission line 

maintenance. See Section 3.1.2 of this appendix for details of maintenance 

requirements. 

Table B-5 provides a breakdown of the amount of land needed temporarily for 

construction and for operation over the life of the Project. During construction, temporary 

permission would be required from landowners and land management agencies for offROW access, staging areas, helicopter fly yards, and material storage. During operation, 

Project land requirements would be restricted to the ROW, including access roads, 

substations, and communication facilities. Access to the ROW would be in accordance 

with the land rights obtained as part of the easement acquisition process. As further 

details of the final Project design are engineered, the amount of land required may 

change. 

2.1.2 Right-of-Way Acquisition

All segments must obtain new ROWs through a combination of ROW grants and 

easements negotiated between the Proponents and various federal, state, and local 

governments; other companies (e.g., utilities and railroads); and private landowners.

Close coordination with all property owners and land agencies during initial surveys and 

the construction phase of the Project is essential for successful completion of the 

Project. In the early stages of the Project, landowners would be contacted to obtain 

right-of-entry for surveys and for geotechnical drilling at selected locations. Each 
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-28

landowner along the final centerline route would be contacted to explain the Project and 

to secure right-of-entry and access to the ROW.

Table B-5. Summary of Land Required for Construction and Operations

Segment

Land Required for 

Construction (acres) 1/, 2/

Land Required for 

Operations (acres) 1/

Segment 1E – Windstar to Aeolus 

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 1,543 1,520

Off-ROW Staging Areas 40 –

Off-ROW Fly Yards 204 –

Off-ROW Access Roads 104 52

OPGW Regeneration Station(s) - 0 – –

Portion of Windstar and Aeolus Substations 23 20

Segment Subtotal 1,914 1,592

Segment 1W(a) – Windstar to Aeolus (230-kV Line)

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 1,179 1,156

Off-ROW Staging Area – –

Off-ROW Fly Yards 45 –

Off-ROW Access Roads 52 27

OPGW Regeneration Station(s) - 1 1 0.53/

Portion of Windstar and Aeolus Substations 23 20

Segment Subtotal 1,300 1,204

Segment 1W(c) – Windstar to Aeolus (230-kV Reconstruction)

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 1,086 1,066

Off-ROW Staging Area 30 –

Off-ROW Fly Yards 305 –

Off-ROW Access Roads 36 18

OPGW Regeneration Station(s) - 0 – -

Portion of Heward and Aeolus Substations 24 20

Segment Subtotal 1,481 1,104

Segment 2 – Aeolus to Creston 

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 3,560 3,502

Off-ROW Staging Area 60 –

Off-ROW Fly Yards – –

Off-ROW Access Roads 83 42

OPGW Regeneration Station(s) - 1 1 0.53/

Portion of Aeolus and Creston Substations 59 51

Segment Subtotal 3,763 3,596

Segment 3 – Creston to Bridger

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 2,083 2,043

Off-ROW Staging Area 40 –

Off-ROW Fly Yards – –

Off-ROW Access Roads 45 23

OPGW Regeneration Station(s) - 0 – –

Portion of Creston, Anticline and Jim Bridger 

Substations 86 75

Segment Subtotal 2,254 2,141
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Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-29

Table B-5. Summary of Land Required for Construction and Operations (continued)

Segment

Land Required for 

Construction (acres) 1/, 2/

Land Required for 

Operations (acres) 1/

Segment 4 – Bridger to Populus 

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 7,498 7,367

Off-ROW Staging Area 98 –

Off-ROW Fly Yards – –

Off-ROW Access Roads 148 74

OPGW Regeneration Station(s) - 3 3 1.53/

Portion of Anticline and Populus Substations 98 89

Segment Subtotal 7,845 7,532

Segment 5 – Populus to Borah 

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 1,699 1,651

Off-ROW Staging Area 40 –

Off-ROW Fly Yards 173 –

Off-ROW Access Roads 57 29

OPGW Regeneration Station(s) - 0 – –

Portion of Populus and Borah Substations 50 44

Segment Subtotal 2,019 1,724

Segment 6 – Borah to Midpoint

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 17 17

Off-ROW Staging Area Staging areas from adjacent 

segments would be used. –

Off-ROW Fly Yards Fly yards from adjacent 

segments would be used. –

Off-ROW Access Roads

Minimal roads would be 

required around substations 

for required work.

–

OPGW Regeneration Station(s) - 0 – –

Portion of Borah and Midpoint Substations 35 31

Segment Subtotal 52 48

Segment 7 – Populus to Cedar Hill 

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 3,655 3,568

Off-ROW Staging Area 60 –

Off-ROW Fly Yards 399 –

Off-ROW Access Roads 59 30

OPGW Regeneration Station(s) - 2 2 1

Portion of Cedar Hill Substation 47 42

Segment Subtotal 4,222 3,641

Segment 8 – Midpoint to Hemingway 

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 4,067 3,968

Off-ROW Staging Area 120 –

Off-ROW Fly Yards 487 –

Off-ROW Access Roads 19 10

OPGW Regeneration Station(s) - 2 2 1

Portion of Midpoint Substation 15 13

Segment Subtotal 4,710 3,992
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-30

Table B-5. Summary of Land Required for Construction and Operations (continued)

Segment

Land Required for 

Construction (acres) 1/, 2/

Land Required for 

Operations (acres) 1/

Segment 9 – Cedar Hill to Hemingway 

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 5,024 4,901

Off-ROW Staging Area 120 –

Off-ROW Fly Yards 565 –

Off-ROW Access Roads 86 43

OPGW Regeneration Station(s) - 2 2 1

Portion of Cedar Hill Substation 17 15

Segment Subtotal 5,814 4,960

Segment 10 – Midpoint to Cedar Hill 

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 1,043 1,006

Off-ROW Staging Area 20 –

Off-ROW Fly Yards 120 –

Off-ROW Access Roads 2 1

'Off-ROW Crossings – –

OPGW Regeneration Station(s) - 0 – –

Portion of Midpoint Substation and Cedar Hill 

Substations 31 28

Segment Subtotal 1,216 1,035

Total Project

T-Line ROW (including Off ROW Wire Pulling/ 

Splicing Sites) 32,454 31,765

Off-ROW Staging Area 628 –

Off-ROW Fly Yards 2,298 –

Off-ROW Access Roads 691 349

OPGW Regeneration Station(s) - 11 11 6

Substation 508 448

Total Project 36,590 32,568

1/ The exact land requirements would depend on the final detailed design of the transmission line, which is influenced 

by the terrain, land use, and economics. Alignment options may also slightly increase or decrease these values.

2/ Acreages in table are rounded to the nearest acre; columns therefore may not sum exactly.

3/ Values are given in 0.5-acre increments because regeneration sites are typically 0.5 acre each.

Assumptions/Notes:

1. ROW widths for 500-kV double circuit and 500-kV single circuit segments are 300 feet and 250 feet, respectively. The 

ROW width for 230-kV H-frame segments is 125 feet. The dimensions of the tower construction pads and area permanently 

occupied by towers after restoration are based on the dimensions specified in Table B-1.

2. The staging areas would serve as field offices, reporting locations for workers, parking space for vehicles and equipment, 

sites for material storage, fabrication assembly and stations for equipment maintenance, and concrete batch plants. 

3. Staging/material storage yards/batch plants would be approximately 20 acres for 500 kV and 10 acres for 230 kV. They 

would be located at each end of a segment, and every 20 to 30 miles along the line.

4. Fly yards would be 10 to 15 acres located approximately every 5 miles. Values in table assume helicopter construction 

throughout all single-circuit 500-kV and 230-kV segments (the double-circuit 500-kV tower is too heavy to utilize helicopter 

construction). The construction contractor may choose to construct using ground-based techniques, therefore not utilizing fly 

yards.

5. For 500 kV, wiring pulling/splicing sites would be the ROW width x 600 feet located approximately every 3 miles; for 230 

kV, ROW width x 400 feet located every 9,300 feet. Typically, only sites that would be off of the ROW would be at large angle 

dead-ends. It is estimated that one in four sites would be off of the ROW.

6. Refer to Table B-7 for access road mileages for each segment.

All negotiations with landowners would be conducted in good faith, and the Project’s 

effect on the parcel or any other concerns the landowner may have would be 

addressed. ROWs for transmission line facilities on private lands would be obtained as 
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-31

perpetual easements. Land for substation or regeneration stations would be obtained in 

fee simple where located on private land. A good faith effort would be made to 

purchase the land and/or obtain easements on private lands through reasonable 

negotiations with the landowners.

Chapter 1, Section 1.3.3.3 describes NERC and WECC reliability standards and 

capacity needs for Gateway West. To achieve the capacity needed to serve present 

and future loads within the Proponents’ service areas, the WECC requires a minimum 

separation from existing transmission lines that serve substantially the same load as 

that served by each of the new Gateway West transmission segments. In these cases, 

the Gateway West transmission lines must be located at least 1,500 feet from the 

nearest existing 230 kV or higher-voltage transmission lines and is being designed to be 

located the maximum span distance away when adjacent to longer spans. Land 

between ROWs that are separated to meet reliability criteria would not be encumbered 

with an easement but could practically be limited in land uses due to the proximity of 

two or more large transmission lines.

2.1.3 Land Disturbance 

Land disturbance as described in Table B-6 is the estimated amount of land that would 

be disturbed during construction or required to be permanently converted to operational 

uses. These uses are less than the amount of land for which operational controls are 

required over the life of the Project as described in Table B-5.

Estimates for construction disturbances are based on best professional judgment and 

experience with this type of project. Estimates were made of disturbance areas resulting 

from each construction activity involving structure placement, access roads, contractor 

and material staging areas, and new and expanded substations. Sections 2.2 through 

2.4 of this appendix describe typical disturbance areas for each construction activity.

2.2 Transmission Line Construction

The following sections detail the transmission line construction activities and procedures 

for Gateway West. Construction equipment and work force requirements are described 

in Section 2.6. Figure B-13 illustrates the transmission line construction sequence. 

Substation construction is described in Section 2.4 of this appendix. Various 

construction activities would occur during the process, with several crews operating 

simultaneously at different locations. The proposed construction schedule is described 

in Section 2.6.4 of this appendix.

For the entire Proposed Route, 1,103 miles of transmission lines and associated 

support structures would be constructed, including 71 miles to be reconstructed. Of this 

total, 847.5 miles would be constructed using 500-kV structures, although one of the 

500-kV circuits on the segment between Aeolus and Anticline would be initially 

energized at 230 kV. Two hundred and fifty-two miles would be constructed using 230-

kV steel H-frame structures and approximately 5.5 miles would be 345-kV construction 

between the proposed Anticline Substation and the expansion of the existing 345-kV 

substation at the Jim Bridger Power Plant.
Gateway West Transmission Line Draft EIS 

Appendix B – Transmission Line and Substation 

Components Common to All Action Alternatives

B-32

Table B-6. Summary of Land Disturbance Resulting from Construction and 

Operations 

Segment/Project Component Land Affected During 

Construction (acres) 1/, 2/ Land Affected During Operations (acres) 1/

Segment 1E 

One Single-Circuit Tower 230-kV Pad 315 42 

Dead-end Angle 230-kV Pulling Sites 44 – 

Existing Roads, Needing Improvement 241 121 

New Access Roads 179 100 

Fly Yards 225 –

OPGW Regeneration Station - 0 1 0.5

Single Circuit Pulling-Tensioning 230-kV 23 –

Staging Yards 230-kV 40 –

Portion of Windstar and Aeolus Substations 23 20 

Segment 1E Subtotal 1,096 283 

Segment 1W(a) 

One Single-Circuit Tower 230-kV Pad 253 34 

Dead-end Angle 230-kV Pulling Sites 42 – 

Existing Roads, Needing Improvement 127 65 

New Access Roads 112 64 

Fly Yards 50 – 

OPGW Regeneration Station - 1 1 –

Single Circuit Pulling-Tensioning 230-kV 13 – 

Staging Yards 230-kV – – 

Portion of Windstar and Aeolus Substations 23 20 

Segment 1W(a) Subtotal 623 182

Segment 1W(c) 

One Single-Circuit Tower 230-kV Pad 228 30 

Dead-end Angle 230-kV Pulling Sites 38 – 

Existing Roads, Needing Improvement 79 41 

New Access Roads 90 52 

OPGW Regeneration Station – 0 1 0.5 

Fly Yards 312 – 

Single-Circuit Pulling-Tensioning 230-kV 12 – 

Staging Yards 230-kV 30 – 

Heward Substation & portion of Aeolus Substation 24 20 

Segment 1W(c) Subtotal 817 144

Segment 2 

One Double-Circuit Tower 500k-V Pad 713 95 

Dead-end Angle Pulling Double-Circuit 500-kV 145 – 

Existing Roads, Needing Improvement 316 163 

New Access Roads 162 91 

OPGW Regeneration Station – 1 1 0.5 

Fly Yards – – 

Double-Circuit Pulling-Tensioning 500-kV 85 – 

Staging Yards 500-kV 60 – 

Portion of Aeolus and Creston Substations 59 51 

Segment 2 Subtotal 1,544 401 

Segment 3 

One Double-Circuit Tower 500-kV Pad 435 58 

Dead-end Angle Pulling Double-Circuit 500-kV 103 –
Gateway West Transmission Line Draft EIS 

Appendix B – Transmission Line and Substation 

Components Common to All Action Alternatives

B-33

Table B-6. Summary of Land Disturbance Resulting from Construction and 

Operations (continued) 

Segment/Project Component Land Affected During 

Construction (acres) 1/, 2/ Land Affected During Operations (acres)

Existing Roads, Needing Improvement 61 31 

New Access Roads 99 56 

Fly Yards – –

OPGW Regeneration Station – 0 – –

Double-Circuit Pulling-Tensioning 500-kV 36 –

Staging Yards 500-kV 40 –

Jim Bridger 345-kV and portion of Creston and

Anticline Substations 

86 75 

Segment 3 Subtotal 863 219 

Segment 4 

One Double-Circuit Tower 500-kV Pad 1,536 205 

Dead-end Angle Pulling Double-Circuit 500-kV 324 –

Existing Roads, Needing Improvement 330 167 

New Access Roads 330 189 

Fly Yards – –

OPGW Regeneration Station – 3 3 1.5 

Double-Circuit Pulling-Tensioning 500-kV 121 –

Staging Yards 500-kV 100 –

Portion of Anticline and Populus Substations 98 89 

Segment 4 Subtotal 2,846 651 

Segment 5 

One Single-Circuit Tower 500-kV Pad 351 14 

Dead-end Angle Pulling Single-Circuit 500-kV 106 –

Existing Roads, Needing Improvement 127 64 

New Access Roads 92 52 

OPGW Regeneration Station – 0 – –

Fly Yards 175 –

Single-Circuit Pulling-Tensioning 500-kV 40 –

Staging Yards 500-kV 40 –

Portion of Populus and Borah Substations 50 44 

Segment 5 Subtotal 982 174

Segment 6 

Portion of Borah and Midpoint Substations 35 31 

Substation Additional Disturbance 30 30 

Segment 6 Subtotal 65 61 

Segment 7 

One Single-Circuit Tower 500-kV Pad 764 31 

Dead-end Angle Pulling Single-Circuit 500-kV 184 –

Fly Yards 400 –

Existing Roads, Needing Improvement 113 59 

New Access Roads 166 99 

OPGW Regeneration Station – 2 2 1 

Single-Circuit Pulling-Tensioning 500-kV 64 –

Staging Yards 500-kV 60 –

Portion of Cedar Hill Substation 47 42 

Segment 7 Subtotal 1,804 231 

Segment 8 

One Single-Circuit Tower 500-kV Pad 827 33 

Dead-end Angle Pulling Single-Circuit 500-kV 218 –

Fly Yards 512 –

Existing Roads, Needing Improvement 182 92 

New Access Roads 170 106 

OPGW Regeneration Station - 2 2 1 

Single-Circuit Pulling-Tensioning 500-kV 77 –
Gateway West Transmission Line Draft EIS 

Appendix B – Transmission Line and Substation 

Components Common to All Action Alternatives

B-34

Table B-6. Summary of Land Disturbance Resulting from Construction and 

Operations (continued) 

Segment/Project Component Land Affected During 

Construction (acres) 1/, 2/ Land Affected During Operations (acres)

Staging Yards 500-kV 120 –

Portion of Midpoint Substation 15 13 

Segment 8 Subtotal 2,125 246 

Segment 9 

One Single-Circuit Tower 500-kV Pad 1,014 41 

Dead-end Angle Pulling Single-Circuit 500-kV 270 –

Fly Yards 612 –

Existing Roads, Needing Improvement 342 174 

New Access Roads 216 128 

OPGW Regeneration Station – 2 2 1 

Single-Circuit Pulling-Tensioning 500-kV 74 –

Staging Yards 500-kV 120 –

Portion of Cedar Hill Substation 17 15 

Segment 9 Subtotal 2,670 359 

Segment 10 

One Single-Circuit Tower 500-kV Pad 222 9 

Dead-end Angle Pulling Single-Circuit 500-kV 75 –

Fly Yards 125 –

Existing Roads, Needing Improvement 43 23 

New Access Roads 29 18 

OPGW Regeneration Station – –

Single-Circuit Pulling-Tensioning 500-kV 3 3 

Staging Yards 500-kV 20 –

Portion of Midpoint Substation and Cedar Hill 

Substations 

31 28 

Segment 10 Subtotal 549 81 

Project Totals

Deadend Pulling 1,548 –

Existing Road - Improved 1,962 1,000

Fly Yard 2,412 –

New Road 1,644 953

Pads (including Segment 6) 6,660 592

Pulling-Tensioning 548 3

Regeneration Site - 11 12 5.53/

Staging Area 630 –

Substation 506 478

Grand Total 15,985 3,033

1/ The exact land requirements would depend on the final detailed design of the transmission line, which is influenced 

by the terrain, land use, and economics. Alignment options may also slightly increase or decrease these values. 

2/ Acreages in table are rounded to the nearest acre; columns therefore may not sum exactly. 

3/ Values are given in 0.5-acre increments because regeneration sites are typically 0.5 acre each. 

Assumptions/Notes:

1. ROW widths for 500-kV double circuit and 500-kV single circuit segments are 300 feet and 250 feet, respectively. The ROW 

width for 230-kV H-frame segments is 125 feet. 

2. The staging areas would serve as field offices, reporting locations for workers, parking space for vehicles and equipment, sites for 

material storage, fabrication assembly and stations for equipment maintenance, and concrete batch plants. 

3. Staging/material storage yards/batch plants would be approximately 20 acres for 500 kV and 10 acres for 230 kV. They would be 

located at each end of a segment, and every 20 to 30 miles along the line. 

4. Fly yards would be 10 to 15 acres located every 5 miles. Values in table assume helicopter construction throughout all singlecircuit 500-kV and 230 kV-segments (the double-circuit 500-kV tower is too heavy to utilize helicopter construction). The construction 

contractor may choose to construct using ground-based techniques, therefore, not utilizing fly yards. 

5. For 500 kV, wiring pulling/splicing sites would be the ROW width x 600 feet located every 3 miles; for 230 kV, ROW width x 400 

feet located every 9,300 feet. Typically, only sites that would be off of the ROW would be at large angle dead-ends. It is estimated 

that one in four sites would be off of the ROW. 

6. Refer to Table B-7 for access road mileages for each segment.
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-35

Figure B-13. Transmission Line Construction Sequence

2.2.1 Transmission Line System Roads

Construction of the new 230-kV and 500-kV transmission lines would require vehicle, 

truck, and crane access to each new structure site for construction crews, materials, 

and equipment. Similarly, construction of other Project components such as staging 

areas and substation sites would require vehicle access.

Transmission line ROW access would be a combination of new access roads, 

improvements to existing roads, and use of existing roads as is. New access roads or 

improvements to existing access roads would be constructed using a bulldozer or 

grader, followed by a roller to compact and smooth the ground. Front-end loaders 

would be used to move the soil locally or off site. Typically, access to the transmission 

line ROW and tower sites requires a 14-foot-wide travel way for straight sections of road 

and a 16- to 20-foot-wide travel way at corners to facilitate safe movement of equipment 

and vehicles. Wherever possible, new access roads would be constructed within the 

proposed transmission line ROW, or existing roads would be used. In other cases, 

access roads would be required between the proposed transmission line and existing 

roads. Erosion control and sedimentation measures such as at-grade water bars, 

culverts, sediment basins, or perimeter control would be installed as required to 

minimize erosion during and subsequent to construction of the Project.

After Project construction, existing and new permanent access roads would be used by 

maintenance crews and vehicles for inspection and maintenance activities. New roads 

created to access tower sites would be revegetated but not restored to original contours 

to allow for emergency access to the tower location and for periodic inspection and 

maintenance activities. Temporary construction roads not required for future 

maintenance access would be restored after completion of Project construction. For 
Gateway West Transmission Line Draft EIS 

Appendix B – Transmission Line and Substation 

Components Common to All Action Alternatives

B-36

example, access roads to staging areas would not be required once the staging area is 

regraded and vegetated. Gates would be installed as required to restrict unauthorized 

vehicular access to the ROW. Roads retained for operations would be seeded with a 

grass mix and allowed to revegetate. For normal maintenance activities, an 8-foot 

portion of the road would be used and vehicles would drive over the vegetation. For 

non-routine maintenance requiring access by larger vehicles, the full width of the access 

road may be used. Access roads would be repaired, as necessary, but not be routinely 

graded. Vegetation (e.g., taller shrubs and trees) that may interfere with the safe 

operation of equipment would be managed on a cyclical basis. 

Table B-7 lists the estimated miles of proposed access roads by segment based on 

preliminary engineering. 

Table B-7. Miles of New and Improved Access Roads1/ 

Segment

New Access Roads

Existing Access Roads to 

be Improved Totals

Miles Acres2/ Miles Acres2/ Miles Acres2/

Segment 1E 104 179 125 241 229 420

Segment 1W(a) 69 112 67 127 136 239

Segment 1W(c) 56 90 43 79 99 169

Segment 2 93 162 114 316 208 478

Segment 3 59 99 32 61 91 160

Segment 4 200 330 172 330 372 660

Segment 5 55 92 67 127 121 219

Segment 6

3/

– – – – – –

Segment 7 109 166 62 113 170 279

Segment 8 113 170 95 182 209 352

Segment 9 135 216 180 342 315 558

Segment 10 19 29 23 43 43 72

Total 1,013 1,644 979 1,961 1,992 3,607

1/ Includes on- and off-ROW access roads.

2/ Acreages in table are rounded to the nearest acre; column therefore may not sum exactly.

3/ The disturbance for new or improved access roads is accounted for under tower disturbance calculation in Table B-6.

2.2.2 Soil Borings 

At the discretion of the Project engineer, soil borings would be completed along the 

route to determine depth to bedrock and the engineering properties of the soil. Based 

on the soil properties, foundation designs will be completed for transmission line towers 

and other structures. Borings would be made with truck- or track-mounted equipment. 

The borings would be approximately 4 inches in diameter, range from 15 to over 60 feet 

deep, and be backfilled with the excavated material upon completion of soil sampling. 

2.2.3 Staging Areas 

Construction of Gateway West would begin with the establishment of staging areas. 

The staging areas would serve as field offices; reporting locations for workers; parking 

space for vehicles and equipment; and sites for material storage, fabrication assembly, 

concrete batch plants, and stations for equipment maintenance. Staging areas, about 

20 acres each for 500-kV construction and 10 acres each for 230-kV construction, 

would be located near each end of each segment of the transmission line ROW, and 

approximately every 20 to 30 miles along the route. Additionally, fly yards for helicopter 
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-37

operations would be located approximately every 5 miles along the route where 

helicopter construction is planned, and would occupy approximately 10 to 15 acres. 

Construction of the transmission line along Segments 2, 3, and 4 would not use 

helicopters due to the size and weight of the proposed double-circuit structures. If 

either the phased single-circuit or two single-circuit design options described in Chapter 

2, Sections 2.1.2 through 2.1.4 is selected, helicopter construction would likely be used.

Staging areas and helicopter fly yards would be fenced and their gates locked. Security 

guards would be stationed where needed. Staging area locations would be finalized 

following discussion with the land management agency or negotiations with landowners. 

In some areas, the staging area may need to be scraped by a bulldozer and a 

temporary layer of rock laid to provide an all-weather surface. Unless otherwise 

directed by the landowner or land manager, the rock would be removed from the 

staging area upon completion of construction and the area would be restored.

Table B-8 lists the frequency and estimated acreage disturbance for staging areas and 

helicopter fly yards by segment based on preliminary engineering. In locating yards, the 

preference is for relatively flat areas with easy existing access to minimize site grading 

and new road construction. The staging areas would be located in previously disturbed 

sites or in areas of minimal vegetative cover where possible. 

Table B-8. Construction Staging Areas and Helicopter Fly Yards

Proposed

Segment

Staging/Material Storage/Batch Plant Fly Yards

Quantity

Approximate Acreage

Quantity

Approximate Acreage

Per Location Total Per Location Total

Segment 1E 4 10 40 18 12.5 225

Segment 1W(a)1/ – – – 4 12.5 50

Segment 1W(c) 3 10 30 25 12.5 313

Segment 22/ 3 20 60 – – –

Segment 32/ 2 20 40 – – –

Segment 42/ 5 20 100 – – –

Segment 5 2 20 40 14 12.5 175

Segment 63/ – – – – – –

Segment 7 3 20 60 32 12.5 400

Segment 8 6 20 120 41 12.5 512

Segment 9 6 20 120 49 12.5 612

Segment 10 1 20 20 10 12.5 125

1/ Co-located with Segment 1W(c).

2/ Fly yards not applicable for the double-circuit 500-kV design.

3/ Staging area and fly yard disturbance are accounted for in the substation calculation.

2.2.4 Site Preparation

Individual structure sites would be cleared to install the transmission line support

structures and facilitate access for future transmission line and structure maintenance. 

Clearing of individual structure sites would be required to install the structures. Clearing 

individual structure sites would be done using a bulldozer to blade the required area. At 

each single-circuit 500-kV structure location, an area approximately 250 feet by 250 feet 

would be needed for construction laydown, tower assembly, and erection at each tower 

site. An area of approximately 300 feet by 250 would be needed for each 500-kV 

double-circuit tower site. An area approximately 150 feet by 125 feet would be required 
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-38

for 230-kV structure locations. This area would provide a safe working space for 

placing equipment, vehicles, and materials. The work area would be cleared of 

vegetation only to the extent necessary. After line construction, all areas not needed for 

normal transmission line maintenance, including fire and personnel safety clearance 

areas, would be graded to blend as near as possible with the natural contours, then 

revegetated as required.

Additional equipment may be required if solid rock is encountered at a structure 

location. Rock-hauling, hammering, or blasting may be required to remove the rock. 

Excess rock that is too large in size or volume to be spread at the individual structure 

sites would be hauled away and disposed of at approved landfills or at a location 

specified by the landowner.

2.2.5 Install Structure Foundations

Table B-1 lists the number of 500-kV, 230-kV, and 345-kV support structures that would 

be installed. Note that for the short interconnections between the proposed Anticline 

Substation and the 230-kV and 345-kV yards at the existing Jim Bridger Substation, the 

230-kV and 345-kV structures were included in the 500-kV structure total.

H-Frame Installation

Each 230-kV H-frame would require the poles to be directly embedded in the ground. 

Holes would be drilled in the ground using a truck- or track-mounted auger. The 

diameter of the hole excavated for embedment is typically the pole diameter plus 

18 inches. The depth is typically 10 percent of the pole length plus 2 feet; in the case of 

this Project, it would be between 9 and 12 feet. When the pole is placed in the hole, 

native or select backfill would be used to fill the voids around the perimeter of the hole. 

When backfill must be imported, material would be obtained from commercial sources 

or from areas free of noxious weed species. See Section 1.1.1 of this appendix for a 

description an H-frame structure and Figure B-1 for an illustration. Similarly, where 

solid rock is encountered, blasting (see Section 2.5.1 of this appendix) may be required.

Lattice Steel Tower Foundations

Each 500-kV support structure would require the installation of foundations, which are 

typically drilled concrete piers. First, four holes would be excavated for each structure. 

The holes would be drilled using truck- or track-mounted augers of various sizes 

depending on the diameter and depth requirements of the hole to be drilled. Table B-2 

provides the dimensions of each of the foundation holes required for each structure. 

See Section 1.1.1 of this appendix for a description of each structure type and Figures 

B-2 and B-3 for structure illustrations. Prior to excavation, topsoil would be stripped 

from the area around the tower and stockpiled to prevent contamination. Excavation 

spoils would be spread around the tower pad upon completion of the foundations. As 

part of final restoration, the stockpiled topsoil would be spread over the excavation 

spoils and revegetated. Each foundation would extend approximately 1 foot above the 

ground level.

Where solid rock is encountered, blasting (see Section 2.5.1 of this appendix), rock 

hauling, or the use of a rock anchoring or micropile system may be required. Micropiles 

are high capacity, small diameter (5-inch to 12-inch) drilled and grouted in-place piles 
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-39

designed with steel reinforcement to primarily resist structural loading. The rock 

anchoring or micropile system would be used in areas where site access is limited or 

adjacent structures could be damaged as a result of blasting or rock hauling activities.

In environmentally sensitive areas with very soft soils, a HydroVac, which uses water 

pressure and a vacuum, may be used to excavate material into a storage tank. 

Alternatively, a temporary casing may be used during drilling to hold the excavation 

open, after which the casing is withdrawn as the concrete is placed in the hole. 

Alternatively, in areas where soil conditions preclude temporary casing withdrawal, it 

may be abandoned in place. The steel would be cut below grade and backfilled once 

the foundation reveal has cured. In areas where it is not possible to operate large 

drilling equipment due to access or environmental constraints, hand digging may be 

required. 

Reinforced-steel anchor bolt cages would be installed after excavation and prior to 

structure installation. These cages are designed to strengthen the structural integrity of 

the foundations and would be assembled at the nearest Project laydown yard and 

delivered to the structure site via flatbed truck or helicopter. These cages would be 

inserted in the holes prior to pouring concrete. The excavated holes containing the 

reinforcing anchor bolt cages would be filled with concrete (Table B-2).

Typically, and because of the remote location of much of the transmission line route, 

concrete would be provided from portable batch plants set up approximately every 

25 miles along the line route in one of the staging areas. Concrete would be delivered 

directly to the site in concrete trucks with a capacity of up to 10 cubic yards. In the more 

developed areas along the route and in proximity to the substations, the construction 

contractor may use local concrete providers to deliver concrete to the site when 

economically feasible. 

2.2.6 Erect Support Structures

The 230-kV H-frame structures would be framed on site. Two methods of assembly can 

be used to accomplish this, the first of which is to assemble the poles, braces, cross 

arms, hardware, and insulators on the ground. A crane is then used to set the fully 

framed structure by placing the poles in the excavated holes. Alternatively, aerial 

framing can be used by setting the poles in the ground first and assembling the braces, 

cross arms, hardware, and insulators in the air. A crane would move along the ROW 

from structure to structure site setting the structures. 

The 500-kV lattice steel structures would be assembled on site, except where helicopter 

delivery is employed, as described in Section 2.5.2 of this appendix. Steel members for 

each structure would be delivered to the site by flatbed truck. Assembly would be 

facilitated on site by a truck-mounted crane. Subsequent to assembly, the structures 

would be lifted onto foundations using a large crane designed for erecting towers. The 

crane would move along the ROW from structure to structure site erecting the towers. 

Figure B-13 illustrates the tower erection sequence. 

2.2.7 String Conductors, Shield Wire, and Fiber Optic Ground Wire

Conductor, shield wire, and OPGW would be placed on the transmission line support 

structures by a process called stringing. The first step to wire stringing would be to 
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-40

install insulators (if not already installed on the structures during ground assembly) and 

stringing sheaves. Stringing sheaves are pulleys that are temporarily attached to the 

lower portion of the insulators at each transmission line support structure to allow 

conductors to be pulled along the line. Figure B-14 illustrates the sequence of steps in 

installing conductors.

Figure B-14. Conductor Installation

Additionally, temporary clearance structures (also called guard structures) would be 

erected where required prior to stringing any transmission lines. The temporary 

clearance structures are typically vertical wood poles with cross arms and are erected at 

road crossings or crossings with other energized electric and communication lines to 

prevent contact during stringing activities. Bucket trucks may also be used to provide 

temporary clearance. Bucket trucks are trucks fitted with a hinged arm ending in an 

enclosed platform called a bucket, which can be raised to let the worker in the bucket 

service portions of the transmission structure as well as the insulators and conductors 

without climbing the structure.

Once the stringing sheaves and temporary clearance structures are in place, the initial 

stringing operation would commence with the pulling of a lighter weight sock line 

through the sheaves along the same path the transmission line would follow. Typically 

the sock line is pulled in via helicopter. The sock line is attached to the hard line, which 

follows the sock line as it is pulled through the sheaves. The hard line would then be 

attached to the conductor, shield wire, or OPGW to pull them through the sheaves into 

their final location. Pulling the lines may be accomplished by attaching them to a 

specialized wire stringing vehicle. Following the initial stringing operation, pulling and 

tensioning the line would be required to achieve the correct sagging of the transmission 

lines between support structures.

Pulling and tensioning sites for 500-kV construction would be required approximately 

every 3 miles along the ROW and would require approximately 5 acres each to 
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accommodate required equipment. Pulling and tensioning sites for 230-kV construction 

would be required approximately every 2 miles along the ROW and would require 

approximately 1.2 acres each to accommodate required equipment. Equipment at sites 

required for pulling and tensioning activities would include tractors and trailers with 

spooled reels that hold the conductors and trucks with the tensioning equipment. To the 

extent practicable, pulling and tensioning sites would be located within the ROW. 

Depending on topography, minor grading may be required at some sites to create level 

pads for equipment. Finally, the tension and sag of conductors and wires would be finetuned, stringing sheaves would be removed, and the conductors would be permanently 

attached to the insulators at the support structures.

At the tangent and small angle structures, the conductors would be attached to the 

insulators using clamps to “suspend” the conductors from the bottom of the insulators. 

At the larger angle dead-end structures, the conductors cannot be pulled through and 

so are cut and attached to the insulator assemblies at the structure “dead ending” the 

conductors. There are two primary methods to attach the conductor to the insulator 

assembly at the dead-end structure. The first method, hydraulic compression fittings, 

uses a large press and pump that closes a metal clamp or sleeve onto the conductor. 

This method requires heavy equipment and is time consuming. The second method, 

implosive fittings, uses explosives to compress the metal together. Implosive fittings do 

not require heavy equipment, but do create noise similar to a gunshot when the primer 

is struck. Implosive sleeves may be set off either one at a time or in groups. The 

implosive type sleeve is faster to install and results in a secure connection between the 

conductor and the sleeve. Implosive sleeves are planned for the Project.

The 500-kV single- and double-circuit lines use a three conductor bundle for each 

phase. At each single-circuit 500-kV dead-end structure, 18 implosive dead-end 

sleeves (six per phase, one for each of the three subconductors on each of the three 

phases, and on each side of the structure) would be required. Additionally, 18 

compression or implosive sleeves would be required to fabricate and install the jumpers 

that connect the conductors from one side of the dead-end structure to the other, for a 

total of 36 sleeves for each single-circuit dead-end structure. Each double-circuit 500-

kV dead-end structure would require twice as many sleeves as for the single-circuit 

structure because there are twice as many conductors to dead-end and jumpers to be 

fabricated, for a total of 72 sleeves for each double-circuit dead-end structure.

The 230-kV single-circuit lines use a two-conductor bundle for each phase. Each 230-

kV dead-end structure would require 12 implosive or compression type sleeves to deadend the conductors and 12 sleeves to fabricate the jumpers, for a total of 24 sleeves at 

each dead-end structure. For the overall Project, approximately 18,000 to 20,000 

compression or implosive fittings would be used.

2.2.8 Cleanup and Site Reclamation

Construction sites, staging areas, material storage yards, and access roads would be 

kept in an orderly condition throughout the construction period. Approved enclosed 

refuse containers would be used throughout the Project. Refuse and trash would be 

removed from the sites and disposed of in an approved manner. Oils or chemicals 

would be hauled to a disposal facility authorized to accept such materials. Open 

burning of construction trash would not be allowed.
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Disturbed areas not required for access roads and maintenance areas around 

structures would be restored and revegetated, as required by the property owner or land 

management agency. Service roads would be decompacted and the topsoil replaced. 

The road prism would not be restored to original contours so that a stable road base is 

present if equipment is needed to access a tower during operation. The landowner, 

land-management agency, or local Natural Resources Conservation Service would be 

consulted regarding the appropriate seed mix and rate to revegetate the road surface. 

Vegetation on an 8-foot width of road surface may be periodically managed to allow 

equipment travel if necessary. Temporary culverts would be removed. Drivable atgrade waterbars would be installed where needed with frequency proportional to road 

slope to prevent erosion of the roadbed. Applicable agency BMPs and unit 

management plan requirements would be implemented. All practical means would be

made to restore the land outside the minimum areas needed for safe operation to its 

original contour and to restore natural drainage patterns along the ROW.

2.3 Communication System

OPGW for the communication system would be installed at the same time as the 

conductors on each of the transmission line structures. It would be spliced and 

tensioned in the same way. 

2.3.1 Regeneration Stations

Similar to the substations, the selected area is graded, vegetation is removed, and a 

layer of crushed rock is installed. Typically, a 12-foot by 32-foot by 9-foot tall building or 

equipment shelter (metal or concrete) would be constructed on the site. An emergency 

generator with a liquid petroleum gas fuel tank would be installed at the site inside the 

fenced area. Two diverse cable routes (aerial and/or buried) from the transmission 

ROW to the equipment shelter would be installed.

2.3.2 Access Road

Regeneration station roads would be constructed using a bulldozer or grader, followed 

by a roller to compact and smooth the ground. Front-end loaders would be used to 

move the soil locally or off site. Either gravel or asphalt would be applied to the 

prepared base layer. 

2.4 Substation Construction 

There would be substation construction activities at 12 locations for the Project. A 

summary of construction equipment to be used at each substation is included in Section 

2.6 of this appendix. The proposed Creston, Anticline, and Cedar Hill Substations 

would be needed to electrically connect the new transmission line segments. In 

addition, expansion of the substation yards at the planned or existing Windstar, Heward, 

Aeolus, Jim Bridger (230-kV and 345-kV yards), Populus, Borah, Midpoint, and 

Hemingway Substations would be required. 

2.4.1 Substation Roads

Substation roads would be constructed using a bulldozer or grader, followed by a roller 

to compact and smooth the ground. Front-end loaders would be used to move the soil 

locally or offsite. Either gravel or asphalt would be applied to the prepared base layer. 
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2.4.2 Soil Boring

Typically, soil borings would be made on a 600-foot grid spacing within the substation, 

particularly at the approximate location of large structures and equipment such as 

transmission line dead ends and transformers, to determine the engineering properties 

of the soil. Borings would be made with truck- or track-mounted equipment. The 

borings would be approximately 4 inches in diameter, range from 15 to over 60 feet 

deep, and be backfilled with the excavated material upon completion of soil sampling.

2.4.3 Clearing and Grading

Clearing of all vegetation would be required for the entire substation area, including a 

distance of about 10 feet outside the fence. This is required for personnel safety due to 

grounding concerns and because of lower clearances to energized conductors within 

the substations as compared to transmission lines. These lower clearances are allowed 

by the NESC because the entire substation is fenced.

An insulating layer on the surface of the substation is required to protect personnel from 

high currents and voltages during electrical fault conditions. Typically, vegetation is 

removed and a 4- to 6-inch layer of crushed rock is applied to the finished surface of the 

substation. Then the substation is usually treated with a soil sterilizer to prevent 

vegetation growth because the vegetation would degrade the insulating qualities of the 

crushed rock. The entire substation area would be graded essentially flat, with just 

enough slope to provide for runoff of precipitation. The substation would be graded to 

use existing drainage patterns to the extent possible. In some cases, drainage 

structures, such as ditches or culverts, may be required. Clearing and grading material 

would be disposed of in compliance with local ordinances. Material from off site would 

be obtained at existing borrow or commercial sites and would be trucked to the 

substation using existing roads and the substation access road.

2.4.4 Storage and Staging Yards

Construction material storage yards may be located outside the substation-fenced area 

near the substation. These storage yards may be part of the substation property or 

leased by the contractor. After construction is completed, all debris and unused 

materials would be removed and the staging/storage yards returned to preconstruction 

conditions by the construction contractor.

2.4.5 Grounding

A grounding system is required in each substation for detection of faults and for 

personnel safety. The grounding system typically consists of buried copper conductor 

arranged in a grid system and driven ground rods, typically 8 to 10 feet long. The 

ground rods and any equipment and structures are connected to the grounding 

conductor. The amount of conductor and length and number of ground rods required 

are calculated based on fault current and soil characteristics.

2.4.6 Fencing

Security fencing is installed around the entire perimeter of each new or expanded 

substation to protect sensitive equipment and prevent accidental contact with energized 

conductors by third parties. This 7-foot-high fence would be constructed of chain link 

with steel posts. One foot of barbed wire or other similar material is installed on top of 
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the chain link yielding a total fence height of 8 feet. Locked gates would be installed at 

appropriate locations for authorized vehicle and personnel access.

2.4.7 Foundation Installation

Foundations for supporting structures are of two types—spread footings or drilled piers. 

Spread footings are placed by excavating the foundation area, placing forms and 

reinforced-steel and anchor bolts, and pouring concrete into the forms. After the 

foundation has been poured, the forms would be removed, and the surface of the 

foundation dressed. Pier foundations are placed in a hole generally made by a track- or 

truck-mounted auger. Reinforced-steel and anchor bolts are placed into the hole using 

a track- or truck-mounted crane. The portion of the foundation above ground would be 

formed. The portion below ground uses the undisturbed earth of the augered hole as 

the form. After the foundation has been poured, the forms would be removed, the 

excavation would be backfilled, and the surface of the foundation dressed. 

Equipment foundations for circuit breakers and transformers would be slab-on-grade 

type. These foundations are placed by excavating the foundation area; placing forms, 

reinforced steel, and anchor bolts (if required); and placing concrete into the forms. 

After the foundations have been poured, the forms would be removed, and the surface 

of the foundation dressed. Where necessary, provision would be made in the design of 

the foundations to mitigate potential problems due to frost. Reinforced steel and anchor 

bolts would be transported to each site by truck, either as a prefabricated cage or loose 

pieces, which would then be fabricated into cages on the site. Concrete would be 

hauled to the site in concrete trucks. Excavated material would be spread at the site or 

disposed of in accordance with local ordinances. Structures and equipment would be 

attached to the foundations by means of threaded anchor bolts embedded in the 

concrete. Some equipment such as transformers and reactors may not require anchor 

bolts. 

2.4.8 Oil Containment

Some types of electrical equipment, such as transformers and some types of reactors 

and circuit breakers, are filled with an insulating mineral oil. Containment structures are 

required to prevent equipment oil from getting into the ground or waterbodies in the 

event of a rupture or leak. These structures take many forms depending on site 

requirements, environmental conditions, and regulatory restrictions. The simplest type 

of oil containment is a pit, of a calculated capacity, under the oil-filled equipment that 

has an oil-impervious liner. The pit is filled with rock to grade level. In case of an oil 

leak or rupture, the oil captured in the containment pit is pumped into tanks or barrels 

and transported to a disposal facility. If required, more elaborate oil containment 

systems can be installed. This may take the form of an on- or off-site storage tank 

and/or oil-water separator equipment depending on site requirements.

2.4.9 Structure and Equipment Installation

Supporting steel structures are erected on concrete foundations as noted above. These 

are set with a track- or truck-mounted crane and attached to the foundation anchor bolts 

by means of a steel base plate. These structures would be used to support the 

energized conductors and certain types of equipment. This equipment is lifted onto the 

structure by means of a truck-mounted crane and bolted to the structures; electrical 
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connections are then made. Some equipment, such as transformers, reactors, and 

circuit breakers, are mounted directly to the foundations without supporting structures. 

These are set in place by means of a truck-mounted crane. Some of this equipment 

requires assembly and testing on the pad. Electrical connections to the equipment are 

then made.

2.4.10 Control Building Construction

One or more control buildings are required at each substation to house protective 

relays, control devices, battery banks for primary control power, and remote monitoring 

equipment. The size and construction of the building depends on individual substation 

requirements. Typically, the control building would be constructed of concrete block, 

pre-engineered metal sheathed, or composite surfaced materials. Once the control 

house is erected, equipment is mounted and wired inside. In some cases an 

emergency generator may be located just outside the control house within the 

substation fenced area.

2.4.11 Conductor Installation

The two main types of high voltage conductors used in substations are tubular 

aluminum for rigid bus sections and/or stranded aluminum conductor for strain bus and 

connections to equipment. Rigid bus would be a minimum of 4 inches in diameter for 

this Project and would be supported on porcelain or polymer insulators on steel 

supports. The bus sections would be welded together and attached to special fittings 

for connection to equipment. Stranded aluminum conductors would be used as flexible 

connectors between the rigid bus and the station equipment. 

2.4.12 Conduit and Control Cable Installation

Most substation equipment requires low-voltage connections to protect relaying and 

control circuits. These circuits allow metering, protective functions, and control (both 

remote and local) of the power system. Connections are made from the control building 

to the equipment through multi-conductor control cables installed in conduits and/or precast concrete cable trench system.

2.4.13 Construction Cleanup and Landscaping

The cleanup operation would be performed after construction activities are completed. 

All waste and scrap material would be removed from the site and deposited in local 

permitted landfills in accordance with local ordinances. Ruts and holes outside the 

substation fence due to construction activities would be regraded. Revegetation and 

restoration would be conducted as required. Landscaping required by the permitting 

agency would use drought-tolerant plant materials. A permanent access road would be 

constructed to the new substation. 

2.5 Special Construction Techniques

2.5.1 Blasting

As described in Section 2.2.5 of this appendix, 500-kV lattice tower foundations would 

normally be installed using drilled shafts or piers and 230-kV H-frame structures would 

be directly embedded. If hard rock is encountered within the planned drilling depth, 

blasting may be required to loosen or fracture the rock in order to reach the required 
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depth to install the structure foundations. Areas where blasting would likely occur have 

been identified based on the geologic setting of the proposed alignment. Table B-9 

summarizes the shallow bed rock conditions within each segment. More precise 

locations where blasting is expected would be identified based on a site-specific 

geotechnical study carried out as part of detailed design.

The construction contractor would be required to prepare an overall Blasting Plan for 

the Project, subject to the approval of the Proponents. The Blasting Plan would detail 

the contractor’s proposals for compliance with the Proponents’ blasting specifications 

and would detail the general concepts proposed to achieve the desired excavations 

using individual shot plans. In addition, the plan would address proposed methods for

controlling fly rock, for blasting warnings, and for use of non-electrical blasting systems. 

The contractor would be required to provide data to support the adequacy of the 

proposed efforts regarding the safety of structures and slopes and to ensure that an 

adequate foundation is obtained. When utilized, blasting would take place between 

sunrise and sunset.

Table B-9. Summary of Shallow Bedrock

Segment 

Number Total Miles

Route Miles within 

1 to 4 feet of 

Shallow Bedrock

Route Miles within 

4 to 8 feet of 

Shallow Bedrock

Route Miles within 

8 to 12 feet of 

Shallow Bedrock

Percent of Proposed 

Route Miles Within 

Shallow Bedrock

1E 100.6 14.7 11.2 15.4 41

1W(a) 76.5 0.8 – 14.6 20

1W(c) 70.6 7.1 – 13.7 29

2 96.7 – – – –1/

3 56.4 37.6 3.1 – 41

4 203.0 52.6 2.8 10.0 32

5 54.6 2.4 12.2 – 27

6 0.5 0.2 0.3 – 100

7 118.1 17.1 22.4 6.9 39

8 131.0 25.3 76.8 9.2 85

9 161.7 72.1 33.0 30.1 84

10 33.6 7.1 0.4 0.6 24

1/ See geotechnical drilling comments below.

The shot plans would detail, including sketches, the drilling and blasting procedures; the 

number, location, diameter, and inclination of drill holes; the amount, type, and 

distribution of explosive per hole and delay; and pounds of explosive per square foot for 

presplitting and smooth blasting. The contractor would be required to maintain 

explosives logs.

Blasting near buildings, structures, and other facilities susceptible to vibration or air 

blast damage would be carefully planned by the contractor and the Proponents and 

controlled to eliminate the possibility of damage to such facilities and structures. The 

Blasting Plan would include provisions for control to eliminate vibration, fly rock, and air 

blast damage.

Blasting would be very brief in duration (milliseconds), and the noise would dissipate 

with distance. Blasting produces less noise and vibration than comparable non-blasting 

methods to remove hard rock. Non-blasting methods include track drill rigs, rock 

breakers, jack hammers, rotary percussion drills, core barrels, and rotary rock drills with 
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rock bits. Which all require much longer time duration to excavate approximately the 

same amount of rock as blasting. 

No readily available data were found to evaluate depth to bedrock at depths greater than 

12 feet. Tables B-1 and B-2 indicate that the majority of transmission tower foundations 

are 20 feet or less deep, but foundations for double circuit 500-kV towers (angle towers 

or dead-ends) may range from 20 to 30 feet deep. In 2010, drilling began in some areas 

of Segments 1 through 4 to support geotechnical evaluations for transmission line 

structures. The drilling was conducted on public land and private land where landowner 

permission was obtained. As a conservative measure, it was assumed that all shallow 

bedrock that would need to be removed would require blasting.

As of the date of this Draft EIS, a total of 124 boreholes have been advanced in 

Segments 1 through 4. Total depths drilled ranged from 15 feet to 66.5 feet. The 

drilling data indicate that 11 borings contained bedrock at depths less than 20 feet 

including one of the geotechnical borings in Segment 2, which intercepted bedrock at a 

depth of 15 feet. Therefore, it is assumed that shallow bedrock could be encountered in 

any of the segments. Due to the lack of depth to bedrock data deeper than 12 feet, the 

amount of shallow bedrock presented in Table B-9 likely underestimates the amount of 

shallow bedrock that will be intercepted during construction.

2.5.2 Helicopter Use

Access roads are required to each tower site for construction and for operation and 

maintenance activities. Helicopters may be used to support these activities. Project 

construction activities potentially facilitated by helicopters may include delivery of 

construction laborers, equipment, and materials to structure sites; structure placement; 

hardware installation; and wire stringing operations. Helicopters may also be used to 

support the administration and management of the Project by the Proponents. The use 

of helicopter construction methods for this Project would not change the length of the 

access road system required for operating the Project because vehicle access is 

required to each tower site regardless of the construction method employed.

The size and weight of the 500-kV double-circuit lattice steel structures preclude the use 

of helicopter erection methods7

. These structures would be erected on site using 

appropriately sized cranes to assemble and erect the towers. The single-circuit 500-kV 

towers weigh less and in some cases it may be desirable to employ heavy lift 

helicopters in the tower erection process. To allow the construction contractor flexibility 

in what construction methods can be used, the construction specification would be 

written to allow the contractor the option of using ground-based or helicopter 

construction methods, or a combination thereof. Use of a helicopter for structure 

erection may be driven by various factors, including access to the structure locations, 

construction schedule, and/or construction economics.

When helicopter construction methods are employed, helicopter construction activities 

would be based at a fly yard, which is a Project-material staging area (see Table B-8). 

The fly yards would be approximately 10 to 15 acres in area and would be sited at 

locations to permit a maximum fly time of 4 to 8 minutes to reach structure locations, 

7 For the Gateway West Project, a typical 500-kV double-circuit tangent tower would weigh approximately 82,000 

pounds. A typical 500 kV single-circuit tangent tower would weigh approximately 46,000 pounds.
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typically at about 5-mile intervals. Fly yards would be used for material storage and 

erection of structure sections prior to transport to the final structure locations for 

installation. Additionally, fueling trucks, maintenance trucks, and operations crews 

would be based in the fly yards. Appropriate dust control measures would be 

implemented at these fly yard locations as well as the locations where helicopters would 

be used along the route.

Prior to installation, each tower structure would be assembled in multiple sections at the 

fly yard. Tower sections or components would be assembled by weight based on the 

lifting capacity of the helicopter in use. The lift capacity of helicopters is dependent on 

the elevation of the fly yard, the tower site, and the intervening terrain. The heavy lift 

helicopters that could be used to erect the single-circuit 500-kV tower sections would be 

able to lift a maximum of 15,000 to 20,000 pounds per flight, depending on elevation. 

After assembly at the fly yard, the tower sections would be attached by cables from the 

helicopter crane to the top four corners of the structure section and airlifted to the 

structure location. Upon arrival at the structure location, the section would be placed 

directly on to the foundation or atop the previous structure section. Guide brackets 

attached on top of each section would assist in aligning the stacked sections. Once 

aligned correctly, line crews would climb the structures to bolt the sections together 

permanently. 

It should be noted that the fly yard locations provided are considered approximate and 

subject to change, additions, or deletions upon acquisition of an installation contractor 

prior to the beginning of construction. Upon completion of field review, a final 

determination would be made on the necessity of certain fly yards and the respective 

locations that provide the most efficient, economic, safest, and least impact use of the 

fly yards that are needed. 

2.5.3 Water Use 

Construction of the transmission lines and substations would require water. Major water 

uses are for transmission line structure and substation foundations, and dust control 

during ROW and substation grading and site work. A minor use of water during 

construction would include the establishment of substation landscaping where required. 

Table B-10 lists the amount of water required for the Project.

Transmission lines use water for two primary purposes: foundation construction and 

ROW dust control. The required water would be procured from municipal sources, from 

commercial sources, or under a temporary water use agreement with landowners 

holding existing water rights. No new water rights would be required. In the 

construction of foundations, water is transported to the batch plant site where it would 

be used to produce concrete. From the batch plant, the wet concrete would be 

transported to the structure site in concrete trucks for use in foundation installation (refer 

to Section 2.2.4 of this appendix for more details on foundation installation). 
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Table B-10. Estimated Water Usage by Component, Segment, and Activity

Transmission Line 

Segments Total Miles

No of 

Structures1/

Foundation Gallons 

per Segment2/

Dust Control 

Gallons per 

Segment3/

Total Gallons 

per Segment

1E 100.6 575 – 2,158,320 2,158,320

1W(a) 76.5 460 – 1,726,656 1,726,656

1W(c) 70.6 416 – 1,561,498 1,561,498

2 96.7 414 1,174,149 1,553,990 2,728,139

3 56.4 253 717,535 949,660.8 1,667,196

4 203 893 2,532,644 3,351,965 5,884,609

5 54.6 245 694,846 919,632 1,614,478

6 0.5 10 28,361 37,536 65,897

7 118.1 534 1,514,481 2,004,422 3,518,904

8 131 577 1,636,434 2,165,827 3,802,261

9 161.7 707 2,005,128 2,653,795 4,658,923

10 33.6 155 439,597 581,808 1,021,405

Total Transmission Line Water Usage (million gallons = MG) 30.4

Substations

Acres of 

Construction 

Disturbance

Gallons for 

Concrete

Gallons for 

Grading/Site 

Work/Dust Control2/

Gallons for 

Substation 

Landscaping

Total Gallons 

per Substation

Windstar Substation 12 9,200 1,703,196 – 1,712,396

Heward Substation 7 5,400 993,531 – 998,931

Aeolus Substation 100 89,000 14,193,330 – 14,282,300

Creston Substation 17 13,000 2,412,861 – 242,5861

Anticline Substation 135 103,000 19,160,955 – 19,263,955

Jim Bridger 345-kV 

Substation

10 7,700 1,419,330 – 1,427,030

Jim Bridger 230-kV 

Substation2/ – – – – –

Populus Substation 90 69,000 12,773,970 – 12,842,970

Borah Substation 40 34,000 5,677,320 – 5,711,320

Midpoint 44 34,000 6,245,052 – 6,279,052

Cedar Hill Substation 50 39,000 7,096,650 – 7,135,650

Hemingway 

Substation

– – – – –

Total Substation Water Usage (MG) 143.8

Regeneration 

Sites Number Gallons for all Activities 

Total Gallons 

Regen Sites

Sites 11 800 8,800

Total Project (MG) 102.5

1/ Water usage per structure is used to make concrete at the batch plant site. 

2/ All 230-kV structures would be directly embedded. Concrete foundations are not required; therefore, no water is required. 

3/ The amount of water used for dust control varies significantly based on many conditions. Estimates are based on

reasonable construction experience.

Construction of the transmission lines and related facilities would generate a temporary 

increase in fugitive dust. If the level of fugitive dust is too high in specific Project areas, 

as determined in cooperation with the landowner or agency, water would be applied to 

disturbed areas to minimize dust.

Water usage for substation construction is primarily for dust control during site 

preparation work. During this period, construction equipment would be cutting, moving, 

and compacting the subgrade surface. As a result, water trucks patrolling the site to 
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control dust would make as many as one pass per hour over the station site. Once site 

preparation work is complete, concrete for the placement of foundations becomes the 

largest user of water and dust control becomes minimal.

Once site grading is complete, the balance of the substation construction work would be 

performed on bare subgrade soil or subgrade with a thin layer of rock. Fire risk would 

be minimal due to the bare ground or rock surface and would be contained within the 

confines of station fenced area.

2.6 Construction Elements

2.6.1 Construction Workforce

The proposed Project would be constructed primarily by contract personnel, with the 

Proponents responsible for Project administration and inspection. The construction 

workforce would consist of laborers, craftsmen, supervisory personnel, support 

personnel, and construction management personnel who would perform the 

construction tasks. Estimated construction workforce requirements are summarized by 

EPC8 contract in Figure B-15. These projections were developed for the various Project 

components by the Proponents’ transmission engineering contractor using project 

planning computer software. Overall, Project construction is expected to occur between 

June 2013 and December 2018, with multiple contractors working concurrently on the 

separate line segments and substations of Gateway West in order to meet the planned 

in-services dates. The first phase would extend from Windstar to Populus, and the 

second phase would extend from Populus to Hemingway, with the last segment being 

complete by the end of 2018. 

The Proponents’ proposed schedule identifies general construction timeframes by 

segment and substation, generally 4 to 5 years (see Table B-17). Construction times by 

segment are, however, expected to range from about 8 months to 27 months; similarly, 

substation construction times would range from 2 to 9 months. This construction would 

take place within the broader timeframes identified in Table B-17, but the exact timing is 

unknown. The combined labor requirements by EPC shown in Figure B-15 are, 

therefore, based on a representative Project schedule that is used in the EIS for the 

purposes of analysis. 

Project-wide, the Project workforce would reach a peak of 745 workers in weeks 58 and 

59. The construction personnel peak on site in any line segment would be when the 

wire stringing operations begin while several other operations are occurring at the same 

time, which would likely include excavating holes, installing foundations (500 kV), 

hauling materials, assembling structures, and erecting/setting structures.

With respect to each substation, installation of the ground grid, installation of the conduit 

and cable trench system, assembly and erection of steel structures, construction of the 

control building, and installation of major equipment would start when the foundations 

are 50 percent complete and would overlap with each other, resulting in the highest 

concentration of the work force on site. 

8 EPC contract means that the final engineering, all or some of the procurement, and the construction are performed 

by one contractor.
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-51

0

100

200

300

400

500

600

700

800

1 10 19 28 37 46 55 64 73 82 91 100 109 118 127 136 145 154 163 172 181 190 199 208 217 226 235 244 253 262 271 280

Week

Number of Jobs

EPC#1 EPC#2 EPC#3

Figure B-15. Total Projected Labor Force by EPC Analysis Area and Week

The substation work is estimated to take between 40 and 60 personnel at each site. 

Site grading requires a small number of people including a surveyor, heavy equipment 

operators, foreman, and construction management personnel. Each station would 

require numerous concrete crews in order to complete the below grade construction and 

concrete placement on schedule. Concrete would be provided by a batch plant 

producing approximately 160 cubic yards per day delivered in 8 cubic yard trucks. 

Other below-grade crews would be needed to install conduit, cable trench, and ground 

mat material. The below-grade crews would be on site overlapping the schedule of the 

concrete crew. Several three-person crews working with boom trucks and bucket trucks 

would erect the steel and install the physical equipment in the yard. Considering the 

size of the substation expansions, this would require approximately three fully equipped 

crews per station. Electrical installation would be handled by 20 people arranged into 

two-person teams alternating between indoor and outdoor activity. Construction would 

generally occur between 7 a.m. and 7 p.m., Monday through Saturday. Additional hours 

may be necessary to make up schedule deficiencies or to complete critical construction 

activities.

2.6.2 Construction Equipment and Traffic

Equipment required for construction of the Gateway West transmission lines and 

substations would include, but is not limited to, that listed in Tables B-11 through B-14. 

These tables also include the anticipated daily duration of equipment use for each 

segment for each type. Table B-15 provides an estimate of the average and peak 

construction traffic during the construction period.
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-52

Table B-11. Transmission Line Construction Equipment Requirements – Segments 1–4

Equipment

Segment 1E Segment 1W(a) Segment 1W(c) Segment 2 Segment 3 Segment 4

Qty.

hrs/ 

day

days/ 

wk Qty.

hrs/ 

day

days/ 

wk Qty.

hrs/ 

day

days/ 

wk Qty.

hrs/ 

day

days/ 

wk Qty.

hrs/ 

day

days/ 

wk Qty.

hrs/ 

day

days/ 

wk

Pickup 10 8 6 10 8 6 10 8 6 37 8 6 37 8 6 37 8 6

Bulldozer 3 4 6 3 4 6 3 4 6 6 4 6 6 4 6 6 4 6

Motor Grader 2 4 6 2 4 6 2 4 6 4 4 6 4 4 6 4 4 6

Water Truck 2 6 6 2 6 6 2 6 6 5 6 6 5 6 6 5 6 6

Hole Digger 2 8 6 2 8 6 2 8 6 3 8 6 3 8 6 3 8 6

Truck (2-ton) 3 5 6 3 5 6 3 5 6 5 5 6 5 5 6 5 5 6

Concrete Truck 0 6 6 0 6 6 0 6 6 6 6 6 6 6 6 6 6 6

Carry All 12 6 6 12 6 6 12 6 6 26 6 6 26 6 6 26 6 6

Hydro Crane 0 7 6 0 7 6 0 7 6 1 7 6 1 7 6 1 7 6

Crane 7 7 6 7 7 6 7 7 6 22 7 6 22 7 6 22 7 6

Wagon Drill 0 5 6 0 5 6 0 5 6 1 5 6 1 5 6 1 5 6

Steel Haul Truck 2 7 6 2 7 6 2 7 6 4 7 6 4 7 6 4 7 6

Fork Lift 3 6 6 3 6 6 3 6 6 5 6 6 5 6 6 5 6 6

Wire Reel Trailer 6 7 6 6 7 6 6 7 6 12 7 6 12 7 6 12 7 6

Diesel Tractor 5 5 6 5 5 6 5 5 6 12 5 6 12 5 6 12 5 6

Boom Truck (5-ton) 3 6 6 3 6 6 3 6 6 6 6 6 6 6 6 6 6 6

Splicing Truck 1 3 6 1 3 6 1 3 6 4 3 6 4 3 6 4 3 6

3-Drum Puller 2 4 6 2 4 6 2 4 6 4 4 6 4 4 6 4 4 6

Single Drum Puller 1 3 6 1 3 6 1 3 6 2 3 6 2 3 6 2 3 6

Tensioner 1 4 6 1 4 6 1 4 6 4 4 6 4 4 6 4 4 6

Sagging Dozer 2 3 6 2 3 6 2 3 6 4 3 6 4 3 6 4 3 6

Static Wire Reel Trailer 2 5 6 2 5 6 2 5 6 4 5 6 4 5 6 4 5 6

Dump Truck 2 4 6 2 4 6 2 4 6 3 4 6 3 4 6 3 4 6

Loader 3 4 6 3 4 6 3 4 6 3 4 6 3 4 6 3 4 6

Light Helicopter 1 6 6 1 6 6 1 6 6 2 6 6 2 6 6 2 6 6

Heavy Helicopter 0 6 6 0 6 6 0 6 6 2 6 6 2 6 6 2 6 6
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-53

Table B-12. Transmission Line Construction Equipment Requirements – Segments 5-10

Equipment

Segment 5 Segment 61/ Segment 7 Segment 8 Segment 9 Segment 10

Qty.

hrs/ 

day

days/ 

wk Qty.

hrs/ 

day

days/ 

wk Qty.

hrs/ 

day

days/ 

wk Qty.

hrs/ 

day

days/ 

wk Qty.

hrs/ 

day

days/ 

wk Qty.

hrs/ 

day

days/ 

wk

Pickup 30 8 6 10 8 6 30 8 6 30 8 6 30 8 6 30 8 6

Bulldozer 6 4 6 2 4 6 6 4 6 6 4 6 6 4 6 6 4 6

Motor Grader 4 4 6 2 4 6 4 4 6 4 4 6 4 4 6 4 4 6

Water Truck 3 6 6 1 6 6 3 6 6 3 6 6 3 6 6 3 6 6

Hole Digger 3 8 6 3 8 6 3 8 6 3 8 6 3 8 6 3 8 6

Truck (2-ton) 4 5 6 2 5 6 4 5 6 4 5 6 4 5 6 4 5 6

Concrete Truck 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6

Carry All 17 6 6 4 6 6 17 6 6 17 6 6 17 6 6 17 6 6

Hydro Crane 1 7 6 1 7 6 1 7 6 1 7 6 1 7 6 1 7 6

Crane 16 7 6 2 7 6 16 7 6 16 7 6 16 7 6 16 7 6

Wagon Drill 1 5 6 1 5 6 1 5 6 1 5 6 1 5 6 1 5 6

Steel Haul Truck 4 7 6 4 7 6 4 7 6 4 7 6 4 7 6 4 7 6

Fork Lift 5 6 6 3 6 6 5 6 6 5 6 6 5 6 6 5 6 6

Wire Reel Trailer 6 7 6 6 7 6 6 7 6 6 7 6 6 7 6 6 7 6

Diesel Tractor 6 5 6 6 5 6 6 5 6 6 5 6 6 5 6 6 5 6

Boom Truck (5-ton) 3 6 6 3 6 6 3 6 6 3 6 6 3 6 6 3 6 6

Splicing Truck 2 3 6 2 3 6 2 3 6 2 3 6 2 3 6 2 3 6

3-Drum Puller 2 4 6 2 4 6 2 4 6 2 4 6 2 4 6 2 4 6

Single Drum Puller 1 3 6 1 3 6 1 3 6 1 3 6 1 3 6 1 3 6

Tensioner 2 4 6 2 4 6 2 4 6 2 4 6 2 4 6 2 4 6

Sagging Dozer 2 3 6 2 3 6 2 3 6 2 3 6 2 3 6 2 3 6

Static Wire Reel Trailer 2 5 6 2 5 6 2 5 6 2 5 6 2 5 6 2 5 6

Dump Truck 3 4 6 1 4 6 3 4 6 3 4 6 3 4 6 3 4 6

Loader 3 4 6 1 4 6 3 4 6 3 4 6 3 4 6 3 4 6

Light Helicopter 1 6 6 1 6 6 1 6 6 1 6 6 1 6 6 1 6 6

Heavy Helicopter 1 6 6 1 6 6 1 6 6 1 6 6 1 6 6 1 6 6

1/ Construction work would involve approximately five transmission line structures at each end of Segment 6 to tie into new substation positions.
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-54

Table B-13. Substation Equipment Requirements – Segments 1–4 

Equipment

Windstar Heward Aeolus Creston Anticline

Qty. hrs/ 

day

days/ 

wk

Qty. hrs/

day

days/ 

wk

Qty. hrs/ 

day

days/ 

wk

Qty. hrs/ 

day

days/ 

wk Qty.

hrs/ 

day

days/ 

wk

Below Grade 

Auger 2 10 6 2 10 6 10 10 6 2 10 6 20 10 6

Backhoe 1 10 6 1 10 6 2 10 6 1 10 6 4 10 6

Front Loader 1 10 6 1 10 6 1 10 6 1 10 6 2 10 6

Ditch Witch 1 10 6 1 10 6 2 10 6 1 10 6 4 10 6

Concrete Truck 2 10 6 2 10 6 10 10 6 2 10 6 20 10 6

Water Truck 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6

Dump Truck 1 10 6 1 10 6 1 10 6 1 10 6 4 10 6

Trailer 2 10 6 2 10 6 2 10 6 2 10 6 2 10 6

Crew Truck/Car 2 10 6 2 10 6 4 10 6 2 10 6 8 10 6

Hauler 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6

Skid Steer Loader 1 10 6 1 10 6 1 10 6 1 10 6 2 10 6

Batch Plant 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6

Drill Rig 1 10 6 1 10 6 1 10 6 1 10 6 2 10 6

Truck with Trailer 2 10 6 2 10 6 4 10 6 2 10 6 4 10 6

Compressor 1 10 6 1 10 6 2 10 6 1 10 6 4 10 6

Construction Fork 1 10 6 1 10 6 1 10 6 1 10 6 2 10 6

980 Loader 1 10 6 1 10 6 1 10 6 1 10 6 2 10 6

Vibrating Roller 1 10 6 1 10 6 1 10 6 1 10 6 2 10 6

Inspection Truck 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6

Above Grade 

Crane 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6

Bucket Truck 2 10 6 2 10 6 2 10 6 2 10 6 4 10 6

Boom Truck 2 10 6 2 10 6 2 10 6 2 10 6 3 10 6

Fork Lift 1 10 6 1 10 6 1 10 6 1 10 6 2 10 6
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-55

Table B-14. Substation Equipment Requirements – Segments 5–10 

Equipment

Jim Bridger 230- and 

345-kV Yards Populus Borah Cedar Hill Midpoint Hemingway 

Qty. hrs/ 

day

days/ 

wk Qty. hrs/ 

day

days/ 

wk Qty. hrs/ 

day

days/ 

wk Qty. hrs/ 

day

days/ 

wk Qty. hrs/ 

day

days/ 

wk Qty. hrs/ 

day

days/ 

wk

Below Grade 

Auger 2 10 6 10 10 6 10 10 6 20 10 6 10 10 6 10 10 6

Backhoe 1 10 6 2 10 6 2 10 6 4 10 6 2 10 6 2 10 6

Front Loader 1 10 6 1 10 6 1 10 6 2 10 6 1 10 6 1 10 6

Ditch Witch 1 10 6 2 10 6 2 10 6 4 10 6 2 10 6 2 10 6

Concrete Truck 2 10 6 10 10 6 10 10 6 20 10 6 10 10 6 10 10 6

Water Truck 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6

Dump Truck 1 10 6 1 10 6 1 10 6 4 10 6 1 10 6 1 10 6

Trailer 2 10 6 2 10 6 2 10 6 2 10 6 2 10 6 2 10 6

Crew Truck/Car 2 10 6 4 10 6 4 10 6 8 10 6 4 10 6 4 10 6

Hauler 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6

Skid Steer 

Loader 1 10 6 1 10 6 1 10 6 2 10 6 1 10 6 10 6

Batch Plant 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6

Drill Rig 1 10 6 1 10 6 1 10 6 2 10 6 1 10 6 1 10 6

Truck with Trailer 2 10 6 4 10 6 4 10 6 4 10 6 4 10 6 4 10 6

Compressor 1 10 6 2 10 6 2 10 6 4 10 6 2 10 6 2 10 6

Construction Fork 1 10 6 1 10 6 1 10 6 2 10 6 1 10 6 1 10 6

980 Loader 1 10 6 1 10 6 1 10 6 2 10 6 1 10 6 10 6

Vibrating Roller 1 10 6 1 10 6 1 10 6 2 10 6 1 10 6 10 6

Inspection Truck 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6

Above Grade

Crane 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6 1 10 6

Bucket Truck 2 10 6 2 10 6 2 10 6 4 10 6 2 10 6 2 10 6

Boom Truck 2 10 6 2 10 6 2 10 6 3 10 6 2 10 6 2 10 6

Fork Lift 1 10 6 1 10 6 1 10 6 2 10 6 1 10 6 1 10 6
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-56

Table B-15. Average and Peak Construction Traffic 

Vehicle Type Average Daily Round Trips Peak Daily Round Trips

Segment 1E

Construction Workers 18 28

Delivery 2 4

Heavy Trucks 10 15

Water Trucks 2 4

Total 32 51

Segment 1W(a)

Construction Workers 13 20

Delivery 2 4

Heavy Trucks 7 11

Water Trucks 2 4

Total 24 39

Segment 1W(c)

Construction Workers 13 20

Delivery 2 4

Heavy Trucks 7 11

Water Trucks 2 4

Total 24 39

Segment 2

Construction Workers 35 50

Delivery 5 8

Heavy Trucks 18 27

Water Trucks 5 8

Total 63 93

Segment 3

Construction Workers 35 50

Delivery 5 8

Heavy Trucks 18 27

Water Trucks 5 8

Total 63 93

Segment 4

Construction Workers 35 50

Delivery 5 8

Heavy Trucks 18 27

Water Trucks 5 8

Total 63 93

Segment 5

Construction Workers 25 40

Delivery 3 6

Heavy Trucks 13 21

Water Trucks 3 6

Total 44 73

Segment 6

Construction Workers 18 30

Delivery 2 4

Heavy Trucks 9 15

Water Trucks 2 4

Total 31 53
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-57

Table B-15. Average and Peak Construction Traffic (continued)

Vehicle Type Average Daily Round Trips Peak Daily Round Trips

Segment 7

Construction Workers 25 40

Delivery 3 6

Heavy Trucks 13 21

Water Trucks 3 6

Total 44 73

Segment 8

Construction Workers 25 40

Delivery 3 6

Heavy Trucks 13 21

Water Trucks 3 6

Total 44 73

Segment 9

Construction Workers 25 40

Delivery 3 6

Heavy Trucks 13 21

Water Trucks 3 6

Total 44 73

Segment 10

Construction Workers 25 40

Delivery 3 6

Heavy Trucks 13 21

Water Trucks 3 6

Total 44 73

Windstar Substation

Construction Workers 2 4

Delivery 2 4

Heavy Trucks 8 12

Water Trucks 8 10

Total 20 30

Heward Substation

Construction Workers 2 4

Delivery 2 4

Heavy Trucks 8 12

Water Trucks 8 10

Total 20 30

Aeolus Substation

Construction Workers 2 4

Delivery 2 4

Heavy Trucks 8 12

Water Trucks 8 10

Total 20 30

Creston Substation

Construction Workers 2 4

Delivery 2 4

Heavy Trucks 8 12

Water Trucks 8 10

Total 20 30
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-58

Table B-15. Average and Peak Construction Traffic (continued)

Vehicle Type Average Daily Round Trips Peak Daily Round Trips

Anticline Substation

Construction Workers 2 4

Delivery 2 4

Heavy Trucks 8 12

Water Trucks 8 10

Total 20 30

Jim Bridger 230-kV and 345-kV Yards

Construction Workers 2 4

Delivery 2 4

Heavy Trucks 8 12

Water Trucks 8 10

Total 20 30

Populus Substation

Construction Workers 2 4

Delivery 2 4

Heavy Trucks 8 12

Water Trucks 8 10

Total 20 30

Borah Substation

Construction Workers 2 4

Delivery 2 4

Heavy Trucks 8 12

Water Trucks 8 10

Total 20 30

Cedar Hill Substation

Construction Workers 2 4

Delivery 2 4

Heavy Trucks 8 12

Water Trucks 8 10

Total 20 30

Midpoint Substation

Construction Workers 2 4

Delivery 2 4

Heavy Trucks 8 12

Water Trucks 8 10

Total 20 30

Hemingway Substation

Construction Workers 2 4

Delivery 2 4

Heavy Trucks 8 12

Water Trucks 8 10

Total 20 30

Construction access would occur at several locations along the transmission line route, 

resulting in dispersed construction traffic. 

The equipment required for transmission line construction is similar for both the 500-kV 

and 230-kV lines, although the equipment needed for 230-kV line construction is 

generally smaller than for 500-kV construction. The following is a summary of 

anticipated equipment to be used for each construction activity. Survey work only 

requires the use of pickup trucks or ATVs. Road construction would utilize pickups, 

bulldozers, motor graders, and water trucks. To dig holes and directly embed the 230-
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-59

kV H-frame poles or install 500-kV foundations it is anticipated that pickup trucks, 2-ton 

trucks, hole diggers, bulldozers, concrete trucks, water trucks, carry alls, cranes, hydro 

crane, wagon drill, dump trucks, and front-end loaders would be used. Hauling steel, or 

poles, braces and hardware for the 230-kV lines, to the structure sites would require the 

use of steel haul trucks, carry alls, cranes, and forklifts. For assembly and erection of 

structures it is anticipated that pickup trucks, 2-ton trucks, carry alls, cranes, and a 

heavy lift helicopter may be used. Wire installation requires the most equipment 

including pickups, wire reel trailers, diesel tractors, cranes, 5-ton boom trucks, splicing 

trucks, three drum pullers, single drum pullers, tensioners, sagging dozers, carry alls, 

static wire reel trailers, and a light helicopter. Final cleanup, reclamation, and 

restoration would utilize pickups, 2-ton trucks, bulldozers, motor graders, dump trucks, 

front-end loaders, and water trucks. The highest level of traffic would be when the wire 

stringing operations begin while several other operations are occurring at the same time 

which would likely include excavating holes, installing foundations, hauling steel, 

assembling structures, and erecting structures.

For the substation work, the highest level of traffic would be during site grading and 

foundation installation. As tabulated in Table B-16, varying amounts of solid waste and soil

not be suitable for re-use at each site would have to be disposed of off site at a remote 

location. Dump trucks would be leaving and returning to the site on a constant basis each 

day for the duration of the site grading. The volume of concrete required at each site will vary 

in proportion to the size of the substation site, and may be up to 7,000 cubic yards of 

concrete at the very large substations. Delivering, placing, and finishing concrete is labor 

intensive. Once concrete placement is complete, traffic on the surrounding roads would 

subside. Workers would arrive in the morning and leave at the end of the day. The balance 

of daily traffic would be material deliveries from storerooms, which would probably be one or 

two trips per day. Each substation would require the delivery of permitted loads such as 

transformers and/or reactors. Each reactor or transformer bank required would require four 

large multiple-wheel lowboy trucks. Delivery would be scheduled to match the completion of 

their respective foundations.

2.6.3 Removal of Facilities and Waste Disposal

Substation and ROW construction would generate a variety of solid wastes including 

concrete, hardware, and wood debris. The solid wastes generated during construction 

would be recycled or hauled away for disposal. Excavation along the ROW and at 

substations would generate solid wastes that could potentially be used as fill; however, 

some of the excavated material would be removed for disposal. Excavated material 

that is clean and dry would be spread along the ROW. The volumes shown in 

Table B-16 reflect the waste that would be hauled away and not disposed of in the 

ROW for each segment during construction of Gateway West.

The majority of waste associated with substation construction results from spoils 

created during site grading. The values shown in Table B-16 reflect the amount of 

vegetation and rock larger than 6 inches in diameter that cannot be processed and 

converted into backfill for compaction. Very little of the soil excavated during foundation 

installation is waste product. Above-grade waste would be packing material such as 

crates, pallets, and paper wrapping to protect equipment during shipping. It is assumed 

a 12-yard dumpster would be filled once a week with waste material for the duration of 

each substation project.
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-60

Table B-16. Solid Waste Generation from Construction Activities 

Total Solid Waste by Substation (cubic yards)

Activity

Windstar

Substation

Heward

Substation

Aeolus 

Substation

Creston 

Substation

Anticline 

Substation

Jim Bridger 

230-kV and 

345-kV Yards

Populus 

Substation

Borah 

Substation

Cedar Hill 

Substation

Midpoint 

Substation

Hemingway 

Substation

Substation Grading/

Site Work 

250 250 8,700 50 16,200 250 2,500 1,400 5,400 4,800 -

Substation Construction 

(Below Grade) 

65 65 474 18 1272 65 601 148 1,075 729 229

Substation Construction 

(Above Grade) 

144 144 192 120 432 144 192 192 432 192 192

Activity

Segment 1E Segment 1W(a) Segment 1W(c) Segment 2 Segment 3/ Segment 4

Excavation 

Removal 

Total (yard3)

Other 

Solid 

Waste 

Total 

(yard3)

Excavation 

Removal 

Total (yard3)

Other 

Solid 

Waste

Total 

(yard3)

Excavation 

Removal 

Total 

(yard3)

Other 

Solid 

Waste 

Total 

(yard3)

Excavation 

Removal 

Total (yard3)

Other 

Solid 

Waste 

Total 

(yard3)

Excavation 

Removal 

Total 

(yard3)

Other 

Solid 

Waste 

Total 

(yard3)

Excavation 

Removal 

Total (yard3)

Other 

Solid 

Waste 

Total 

(yard3)

230-kV Structure Installation 

230-kV Sgl Ckt - H-frame Family (includes angle 

& dead-ends) 0 337,801 0 163,500 0 160,100 - - - - - -

500-kV Structure Installation 

500-kV Sgl Ckt - Tangent Lattice Tower - - - - - - - - - - - -

500-kV Sgl Ckt - Small Angle Lattice Tower - - - - - - - - - - - -

500-kV Sgl Ckt - Medium Angle Lattice Tower - - - - - - - - - - - -

500-kV Sgl Ckt - Medium Dead-End Lattice Tower - - - - - - - - - - - -

500-kV Sgl Ckt - Heavy Dead-End Lattice Tower - - - - - - - - - - - -

500-kV Dbl Ckt - Tangent Lattice Tower - - - - - - 0 302,595 0 178,086 0 657,257

500-kV Dbl Ckt - Small Angle Lattice Tower - - - - - - 0 43,228 0 25,441 0 93,894

500-kV Dbl Ckt - Medium Angle Lattice Tower - - - - - - 0 21,614 0 12,720 0 46,947

500-kV Dbl Ckt - Medium Dead-End Lattice Tower - - - - - - 0 43,228 0 25,441 0 93,894

500-kV Dbl Ckt - Heavy Dead-End Lattice Tower - - - - - - 0 21,614 0 12,720 0 46,947

Activity

Segment 5 Segment 6 Segment 7 Segment 8 Segment 9 Segment 10

Excavation 

Removal 

Total (yard3)

Other 

Solid 

Waste 

Total 

(yard3)

Excavation 

Removal 

Total (yard3)

Other 

Solid 

Waste 

Total 

(yard3)

Excavation 

Removal 

Total 

(yard3)

Other 

Solid 

Waste 

Total 

(yard3)

Excavation 

Removal 

Total (yard3)

Other 

Solid 

Waste 

Total 

(yard3)

Excavation 

Removal 

Total 

(yard3)

Other 

Solid 

Waste 

Total 

(yard3)

Excavation 

Removal 

Total (yard3)

Other 

Solid 

Waste 

Total 

(yard3)

230-kV Structure Installation 

230-kV Sgl Ckt - H-frame Family (includes angle 

& dead-ends) - - - - - - - - - - - -

500-kV Structure Installation 

500-kV Sgl Ckt - Tangent Lattice Tower 0 66,286 0 2,933 0 147,530 0 164,248 0 198,271 0 41,355

500-kV Sgl Ckt - Small Angle Lattice Tower 0 9,469 0 419 0 21,076 0 23,464 0 28,324 0 5,908

500-kV Sgl Ckt - Medium Angle Lattice Tower 0 4,735 0 210 0 10,538 0 11,732 0 14,162 0 2,954

500-kV Sgl Ckt - Medium Dead-End Lattice Tower 0 9,469 0 419 0 21,076 0 23,464 0 28,324 0 5,908

500-kV Sgl Ckt - Heavy Dead-End Lattice Tower 0 4,735 0 210 0 10,538 0 11,732 0 14,162 0 2,954

500-kV Dbl Ckt - Tangent Lattice Tower - - - - - - - - - - - -

500-kV Dbl Ckt - Small Angle Lattice Tower - - - - - - - - - - - -

500-kV Dbl Ckt - Medium Angle Lattice Tower - - - - - - - - - - - -

500-kV Dbl Ckt - Medium Dead-End Lattice Tower - - - - - - - - - - - -

500-kV Dbl Ckt - Heavy Dead-End Lattice Tower - - - - - - - - - - - -
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-61

2.6.4 Construction Schedule

The Proponents intend to continue to refine the design of the Gateway West during the 

BLM approval process in order to immediately commence construction if the Project is 

approved. Final engineering surveys would determine the exact locations of towers, 

access roads, and other features prior to the start of construction and would be included 

in the Plan of Development. Due to the broad scope of construction, the varied nature 

of construction activities, and the geographic diversity of the Project area, the 

Proponents intend to hire multiple contractors to complete Project work within the 

projected timeframe and in accordance with industry performance standards. The 

Proposed Action would involve three separate EPC contracts and division of the Project 

into discrete construction phases. Table B-17 shows the planned construction start and 

end dates for each phase. Multiple segments would be under construction at the same 

time. The Proponents developed a Project construction schedule based on this 

strategy. The greatest construction activity would occur in the first 2 years. 

Although the construction rate of progress would be reduced in the winter, the 

Proponents have planned an aggressive schedule and it is anticipated that construction 

would continue through the winter months in the lower-elevation areas of the Project, 

except during winter storms. In the higher-elevation areas of the Project, winter storms 

and snow would limit access to the ROW, for example in Segment 4 in western 

Wyoming and eastern Idaho. In these areas, it is expected that construction would be 

suspended on some portions of the ROW during the peak winter months and 

construction resources would either be demobilized or shifted to other segments of the 

Project.

Transmission line construction commences with contractor mobilization. The contractor 

would mobilize equipment and personnel to the construction site at various stages in the 

Project schedule depending on operational requirements. This would cumulatively 

require approximately 6 weeks throughout the schedule for each segment. 

Construction management, engineering support, inspection, materials handling, and 

administration are required throughout the Project. First, surveyors would start at one 

end of the segment and stake the locations of access roads. Road construction can 

start 1 to 2 weeks after the surveyors begin, which may require clearing in higher 

elevations where tree removal is required prior to road construction. After a couple of 

weeks of road construction another survey crew can begin staking the structure 

locations. A week or two after the survey crew starts staking structure locations, 

excavation of holes for foundations for 500-kV towers, or for directly embedded poles 

for 230-kV structures, can begin. For 500-kV construction, the installation of the 

concrete pier foundations would begin within the next couple of weeks. The foundations 

need time to cure and develop to full structural strength (i.e., compression capacity) 

before lattice towers can be installed. Five to six weeks after foundation installation has 

begun, lattice tower assembly and erection can begin. For 230-kV construction, 

structure assembly and setting can begin immediately after the excavation of holes has 

begun. For 230-kV and 500-kV construction, the wire installation crews would start 

approximately 8 to 12 weeks after assembly and erection/setting begins. This would be 

followed by final cleanup, reclamation, and restoration.
Gateway West Transmission Line Draft EIS

Appendix B – Transmission Line and Substation

Components Common to All Action Alternatives

B-62

1 Table B-17. Construction Schedule

Segment 

Number

Segment or Substation 

Name

Primarily Wyoming Primarily Idaho

Phase 1 Phase 1 Phase 2

Start June 2013 End Dec 2018 Start Mar 2013 End Dec 2018 Start May 2015 End Dec 2018

Windstar Substation Windstar Expansion

Heward Substation Heward Substation

Aeolus Substation Aeolus Expansion

Creston Substation Creston Substation

Populus Substation Populus Expansion

Anticline Substation Anticline (Includes 230-kV and 

345-kV bays at existing Jim Bridger 

Substation)

1E Windstar – Aeolus #2 Single-Circuit 230-kV

1W(a) Windstar – Aeolus #1 Single-Circuit 230-kV and rebuild a 

short section of the existing singlecircuit 230-kV line

1W(c) Dave Johnston – Heward 

–Aeolus

Rebuild the existing single circuit 230-

kV and build a short section a new 

single-circuit 230 kV line

2 Aeolus – Creston Double-Circuit 500-kV 1/

3 Creston – Anticline Double-Circuit 500-kV 1/

3A Anticline – Jim Bridger 

345-kV Substation

Single-Circuit 345-kV

3B Jim Bridger 230-kV 

Substation 2/ Single-Circuit 230-kV

4 Anticline – Populus Double-Circuit 500-kV

Populus Substation Populus Expansion

Cedar Hill Substation Cedar Hill Substation

Hemingway Substation Hemingway Expansion

7 Populus – Cedar Hill Single-Circuit 500-kV

9 Cedar Hill – Hemingway Single-Circuit 500-kV

10 Midpoint – Cedar Hill Single-Circuit 500-kV

Borah Substation Borah Expansion

Midpoint Substation Midpoint Expansion

Hemingway Substation Hemingway Expansion

5 Populus – Borah Single-Circuit 500-kV

6 Borah – Midpoint 3/ Existing single-circuit

8 Midpoint – Hemingway Single-Circuit 500-kV

1/ Constructed to 500-kV standards but one circuit initially operated at 230 kV and the other at 500 kV.

2/ Termination for Creston – Anticline circuit when initially operated at 230 kV.

3/ Existing single circuit constructed to 500-kV standards (energized from 345 kV to 500 kV).
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Substation construction includes five activities: 1) site grading (grading and access road 

development), 2) below-grade construction (primarily the installation of foundations, 3) 

above-grade construction (steel erection and building construction), 4) electrical 

(installation and termination of control wiring), and 5) testing (functional testing of control 

and monitoring schemes). Typically, these activities overlap and complement each other, 

allowing the construction of a substation to proceed more quickly than line construction. It 

is estimated that the site grading activity and access road work for Gateway West 

substations would take 4 to 8 weeks to complete, depending on the size of the site. 

Below-grade construction can be completed in 3 months or less for all substations that 

are expansions of existing substations. In these cases the basic infrastructure is already 

in place, having been installed with the initial substation and designed for the future 

expansion requirements. Only the new substations would take longer to complete.

Above-grade construction duration is highly dependent on the level of construction force 

the contractor chooses. Due to the size of each station, many crews can work on steel 

erection and equipment assembly without interfering with each other. The greatest 

amount of schedule recovery or acceleration in a station’s construction schedule can be 

achieved during this timeframe. It is estimated that for the majority of the substations the 

erection of steel, bus assembly, and major equipment assembly can be completed in 

between 4 months for the smaller substations and 6 months for the larger substations.

Electrical construction is a long and labor-intensive task. Although multiple crews can 

work in a yard at any given time, the space in a control building is very limited and 

would determine the length of this task. In the case of each of these stations, given the 

size and type of equipment to be installed, there would be miles of cable to be pulled 

into conduit and duct banks and thousands of connections to be made and double 

checked prior to the start of testing. New substations would take longer than existing 

substations that already have the basic infrastructure in place.

Prior to starting construction, the Proponents may be required to conduct on-site surveys 

in accordance with applicable protocols or mitigation measures adopted by BLM and 

other agencies as Project conditions. Accordingly, adjustments might occur to the Project 

schedule as necessary to avoid sensitive resources. Pre-construction activities, including 

pre-construction environmental surveys, materials procurement, design, contracting, 

ROW acquisition, and permitting efforts, are not shown in the summary schedule.

The schedule is predicated upon the Proponents’ ability to complete the following tasks 

in a timely manner:

• Secure all necessary permit approvals;

• Secure agency support;

• Complete biological and cultural survey work;

• Construct within environmental time constraints;

• Order and receive equipment;

• Secure construction contractor resources and associated construction equipment; 

and

• Maintain continuous construction activity with no delay due to environmental, 

administrative, or legal issues.
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3 SYSTEM OPERATIONS AND MAINTENANCE

The 500-kV transmission lines to be constructed as part of the Project will comprise 

critical infrastructure of the RMP and Idaho Power transmission systems, and of the 

western U.S. electrical grid. Limiting the duration of unplanned outages and planning 

for the use of live-line maintenance techniques to minimize the requirement for any 

outages is an important part of the design, construction, and operations/maintenance 

requirements for this Project. 

3.1 Routine System Operation and Maintenance

The goal of the Proponents is to provide their customers with a reliable supply of 

electricity while maintaining the overall integrity of the regional electrical grid. The 

Proponents’ obligation to maintain reliable operation of the electrical system is 

documented in the Proponents’ agreements with the various states through the public 

service commissions and is directed through compliance with industry standard codes 

and practices such as the NESC (ANSI C2), which governs the design and operation of 

high-voltage electric utility systems.

In 2005, Congress passed the Energy Policy Act of 2005, which provided a regulatory 

basis for the implementation of specific incentives (and penalties) for maintaining 

reliable service, among other issues. As a result of the passage of the Act, the FERC 

selected the NERC to act as the enforcement agency for compliance with electric utility 

reliability and operating standards, among other issues. The Proponents are required to 

be in compliance with the various reliability standards promulgated through the 

implementation of the NERC policies and procedures. Additionally, PacifiCorp and 

Idaho Power are governed by the WECC standards that may be in addition to or more 

stringent than those currently required by NERC (see also Section 1.3.3.3 for further 

description of these regulatory agencies). In response, the Proponents have prepared 

internal operation and maintenance policies and procedures designed to meet the 

requirements of the NERC, WECC, and the state public utility commissions, while 

remaining in compliance with the applicable codes and standards with respect to 

maintaining the reliability of the electrical system.

Operations and maintenance activities would include transmission line patrols, climbing 

inspections, tower and wire maintenance, insulator washing in selected areas as 

needed, and access roads repairs. The Proponents would keep necessary work areas 

around structures clear of vegetation and would limit the height of vegetation along the 

ROW. Periodic inspection and maintenance of each of the substations and 

communications facilities is also a key part of operating and maintaining the electrical 

system. The following sections provide details on the anticipated operation and 

maintenance activities for Gateway West.

After the transmission line has been energized, land uses that are compatible with 

safety regulations would be permitted in and adjacent to the ROW. Existing land uses 

such as agriculture and grazing are generally permitted within the ROW. Incompatible 

land uses within the ROW include construction and maintenance of inhabited dwellings 

and any use requiring changes in surface elevation that would affect electrical 

clearances of existing or planned facilities.
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Land uses that comply with local regulations would be permitted adjacent to the ROW. 

Compatible uses of the ROW on public lands would have to be approved by the 

appropriate agency. Permission to use the ROW on private lands would have to be 

obtained from the utility owning the transmission line.

3.1.1 Routine System Inspection, Maintenance, and Repair

Regular inspection of transmission lines, substations, and support systems is critical for 

safe, efficient, and economical operation of the Project.

3.1.2 Transmission Line Maintenance

Regular ground and aerial inspections would be performed in accordance with the 

Proponents’ established policies and procedures for transmission line inspection and 

maintenance. The Proponents’ transmission lines and substations would be inspected 

for corrosion, equipment misalignment, loose fittings, vandalism, and other mechanical 

problems. The need for vegetation management would also be determined during 

inspection patrols.

Inspection of the entire transmission line system would be conducted semi-annually. 

Aerial inspection would be conducted by helicopter semi-annually and would require two 

or three crew members, including the pilot. Detailed ground inspections would take 

place on an annual basis using service roads to each structure. Ground inspection 

would use 4x4 trucks or 4x4 ATVs. The inspector would assess the condition of the 

transmission line and hardware to determine if any components need to be repaired or 

replaced, or if other conditions exist that require maintenance or modification activities. 

The inspector would also note any unauthorized encroachments and trash dumping on 

the ROW that could constitute a safety hazard. The inspector would access each of the 

structure locations along each line and use binoculars and spotting scopes to perform 

this inspection.

3.1.3 Hardware Maintenance and Repairs

Routine maintenance activities are ordinary maintenance tasks that have historically 

been performed and are regularly carried out on a routine basis. The work performed is 

typically repair or replacement of individual components (no new ground disturbance), 

performed by relatively small crews using a minimum of equipment, and usually is 

conducted within a period from a few hours up to a few days. Work requires access to 

the damaged portion of the line to allow for a safe and efficient repair of the facility. 

Equipment required for this work may include 4-wheel-drive trucks, material (flatbed) 

trucks, bucket trucks (low reach), boom trucks (high reach), or personnel lifts. This work 

is scheduled and is typically required due to issues found during inspections. Typical 

items that may require periodic replacement on a 500-kV tower include insulators, 

hardware or tower members. It is expected that these replacements would be required 

infrequently.

The Proponents plan to conduct maintenance on the critical 500-kV and 230-kV system 

using live line maintenance techniques. Maintenance on the transmission lines can be 

completed safely using live line techniques thereby avoiding an outage to the critical 

transmission line infrastructure. High reach bucket trucks along with other equipment 

are used to conduct these activities. For the 500-kV lattice tower structures, this 

requires that adequate space be available at each structure site so that the high reach 
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bucket truck can be positioned to one side or the other of the structure and reach up 

and over the lower phases to access the upper center phase for live-line maintenance 

procedures. For the 230-kV H-frame structures, this requires that adequate space be 

available at each structure site so that a bucket truck can be positioned to access the 

outside phases. To allow room at each structure for these activities, in low slope areas 

a pad area is required with the structure in the center of 300 feet (ROW width) by 100 

feet longitudinal for the double-circuit 500-kV structure, 250 feet by 100 feet for the 

single-circuit 500-kV structure, and 125 feet by 50 feet for the 230-kV H-frame structure. 

Figures B-16 through B-18 depict the space requirements for live-line maintenance. 

The size and location of these required pads near the structures may vary depending on 

the side slope and access road at each site. The work areas and pads would be 

cleared to the extent needed to safely complete the work. These pads would remain in 

place after construction, but would be revegetated after the initial construction is 

completed.

3.1.4 Access Road and Work Area Repair

ROW repairs include grading or repair of existing maintenance access roads and work 

areas, and spot repair of sites subject to flooding or scouring. Required equipment may 

include a grader, backhoe, four-wheel-drive pickup truck, and a tracked-loader or 

bulldozer. The cat-loader has steel tracks whereas the grader, backhoe, and truck 

typically have rubber tires. Repairs to the ROW would be scheduled as a result of line 

inspections, or would occur in response to an emergency situation.

3.1.5 Vegetation Management

The Proponents must maintain work areas adjacent to electrical transmission structures 

and along the ROW for vehicle and equipment access necessary for operations, 

maintenance, and repair, including for live-line maintenance activities as described in 

Section 3.1.3, under Hardware Maintenance and Repairs. During schedule vegetation 

management activities, tall growing species, large shrubs and other obstructions would 

be removed near structures to facilitate a safe working environment for inspection and 

maintenance of equipment and to ensure system reliability. At a minimum, trees and 

large brush would be cleared within a 25-foot radius of the base or foundation of all 

electrical transmission structures, and to accommodate equipment pads to conduct live 

line maintenance operations as noted.

Vegetation management practices along the ROW would be in accordance with the 

Idaho Power and PacifiCorp clearing specifications and vegetation management plans 

(Idaho Power 2008; PacifiCorp 2007c; and Appendix C-4). Much of the transmission 

line route traverses arid country characterized by low-growing vegetation, while higher 

elevations receive more precipitation and exhibit more vegetation. The wire-border 

zone method to controlling vegetation is an approach used by PacifiCorp (2007c). This 

method results in two zones of clearing and revegetation. The wire zone is the linear 

area along the ROW under the wires and extending 10 feet outside of the outermost 

phase conductor. After initial clearing, vegetation in the wire zone would be maintained 

to consist of native grasses, legumes, herbs, ferns, and other low-growing shrubs that 

remain under 5 feet tall at maturity. The border zone is the linear area along each side 

of the ROW extending from the wire zone to the edge of the ROW. Vegetation in the 

border zone would be maintained to consist of tall shrubs or short trees (up to 25 feet 
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Figure B-16. Live-line Maintenance Space Requirements, 230 kV
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Figure B-17. Live-line Maintenance Space Requirements, Single-Circuit 500 kV
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Figure B-18. Live-line Maintenance Space Requirements, Double-Circuit 500 kV
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high at maturity), grasses, and forbs. These cover plants benefit the ROW by 

competing with and excluding undesirable plants. The width of the wire and border 

zones is depicted in Figure B-19 for the 230-kV H-frame and single- and double-circuit 

tower line segments. During operations, vegetation growth would be monitored and 

managed to maintain the wire-border zone objectives. Idaho Power’s approach is to 

remove all tree species within the ROW where the conductor ground clearance is less 

than 50 feet, leaving grasses, legumes, herbs, ferns, and low-growing shrubs within the 

ROW. When conductor ground clearance is greater than 50 feet, for example a canyon 

or ravine, the Proponents make provisions for allowing trees and shrubs to remain, 

provided they do not violate minimum clearance thresholds set forth by their respective 

companies.

Vegetation would be removed using mechanical equipment such as chain saws, weed 

trimmers, rakes, shovels, mowers, and brush hooks. Clearing efforts in heavy growth 

areas would use equipment such as a Hydro-Ax or similar. The duration of activities 

and the size of crew and equipment required would depend on the amount and size of 

the vegetation to be trimmed or removed. 

In selected areas, herbicides may be used to control noxious weeds and to meet 

vegetation management objectives. All herbicide applications would be performed in 

accordance with federal, state, and local regulations, and in compliance with managing 

land agency requirements. 

3.1.6 Substation and Regeneration Station Maintenance

Substation and regeneration station monitoring and control functions are performed 

remotely from the Proponents’ central operations facilities located at PacifiCorp’s 

operation center in Portland, Oregon, and by Idaho Power from their operation center in 

Boise, Idaho. Unauthorized entry into substations or regeneration stations is prevented 

with the provision of fencing and locked gates. Warning signs would be posted and 

entry to the operating facilities would be restricted to authorized personnel. Gateway 

West substations and regeneration stations would not be staffed; however, a remotely 

monitored security system would be installed. Several forms of security are planned for 

each of the locations, although the security arrangements at each of the substations or 

regeneration stations may differ somewhat. Security measures may include fire 

detection in the control building via the remote monitoring system; alarming for forced 

entry; and a perimeter security system coupled with remote sensing infrared camera 

equipment in the fenced area of the station to provide visual observation/confirmation to 

the system operator of disturbances at the fence line.

Maintenance activities include equipment testing, equipment monitoring and repair, and 

emergency and routine procedures for service continuity and preventive maintenance. 

It is anticipated that maintenance at each substation would require approximately six 

trips per year by a 2- to 4-person crew. Routine operations would require one or two 

workers in a light utility truck to visit the substations monthly. Typically, once per year a 

major maintenance inspection would take place requiring up to 15 personnel for 1 to 3 

weeks. Regeneration stations would be visited every 2 to 3 months by one individual in 

a light truck to inspect the facilities. Annual maintenance would be performed by a two 

man crew in a light truck over a 2- to 5-day period. If substation landscaping is required 
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Single Circuit 230 kV

Single-Circuit 500 kV

Double-Circuit 500 kV

Figure B-19. Right-of-Way Vegetation Management
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Figure B-20. Right-of-Way Vegetation Management in Steep Terrain

by the permitting agency, drought-tolerant plant materials would be used to minimize 

watering requirements after plant establishment. 

Safety lighting at the substations would be provided inside the substation fence for the 

purpose of emergency repair work. Because night activities are not expected to occur 

more than once per year, the safety lighting inside the substation fence would normally 

be turned off. One floodlight, mounted near the entry gate to safely illuminate the 

substation entry gate, may be left on during nighttime hours.

3.2 Emergency Response

The operation of the system is remotely managed and monitored from control rooms at 

PacifiCorp’s operation center in Portland, Oregon, and by Idaho Power from their 

operation center in Boise, Idaho. Electrical outages or variations from normal operating 

protocols would be sensed and reported at these operation centers. As well, the 

substations are equipped with remote monitoring, proximity alarms, and in some cases 

video surveillance.

Zone Plant Species

Zone A: Grasses, legumes, herbs, 

ferns and low growing shrubs.

Zone B: all deciduous and conifer 

trees.

Zone Definition

Zone A: When the conductor to ground clearance 

is less than 50’, all tree species should be 

removed.

Zone B: When the conductor to ground clearance 

is greater than 50’, all tree species should be 

removed if they have less than 50’ of clearance, 

25’ minimum.
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The implementation of routine operation and maintenance activities on powerlines 

would minimize the need for most emergency repairs. Emergency maintenance 

activities are often those activities necessary to repair natural hazard, fire, or humancaused damages to a line. Such work is required to eliminate a safety hazard, prevent 

imminent damage to the powerline, or restore service if there is an outage. In an 

emergency, the Proponents must respond as quickly as possible to restore power.

The equipment necessary to carry out emergency repairs is similar to that necessary to 

conduct routine maintenance, in most cases. Emergency response to outages may 

require additional equipment to complete the repairs. For example, where the site of 

the outage is remote, helicopters may be used to respond quickly to emergencies.

In practice, as soon as an incident is detected, the control room dispatchers would notify 

the responsible operations staff in the area(s) affected and crews and equipment would 

be organized and dispatched to respond to the incident.

Fire Protection

All federal, state, and county laws, ordinances, rules, and regulations pertaining to fire 

prevention and suppression would be strictly adhered to. All personnel would be 

advised of their responsibilities under the applicable fire laws and regulations.

When working on Public Lands, the Proponents’ employees and contractors would carry 

required suppression tools and equipment. The Proponents or their construction 

contractor would notify local fire authorities and the BLM or Forest Service (as 

appropriate) if a Project-related fire occurs within or adjacent to a construction area.

If the Proponents become aware of an emergency situation that is caused by a fire on 

or threatening BLM-managed or NFS lands and that could damage the transmission 

lines or their operation, they would notify the appropriate agency contact. Specific 

construction-related activities and safety measures would be implemented during 

construction of the transmission line to prevent fires and to ensure quick response and 

suppression if a fire occurs. Typical practices to prevent fires during construction and 

maintenance/repair activities include brush clearing prior to work, stationing a water 

truck at the job site to keep the ground and vegetation moist in extreme fire conditions, 

enforcing red flag warnings, providing “fire behavior” training to all pertinent personnel, 

keeping vehicles on or within designated roads or work areas, and providing fire 

suppression equipment and emergency notification numbers at each construction site. 
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4 DECOMMISSIONING

The proposed transmission line would have a projected operational life of 50 years or 

longer. At the end of the useful life of the Project and if the facility were no longer 

required, the transmission line would be removed from service. At such time, 

conductors, insulators, and hardware would be dismantled and removed from the ROW. 

Structures would be removed and foundations removed to below ground surface.

Following abandonment and removal of the transmission line structures and equipment 

from the ROW, any areas disturbed during line dismantling would be restored and 

rehabilitated. In the same way, if a substation is no longer required, the substation 

structures and equipment would be dismantled and removed from the site. The station 

structures would be disassembled and either re-used at another station or sold for 

scrap. Major equipment such as breakers, transformers, and reactors would be 

removed, refurbished, and stored for use at another facility. Foundations would be 

either abandoned in-place or cut off below ground level and buried. 

The Proponents describe roads necessary for the operation and maintenance of 

transmission lines as either access roads or service roads. The sole purpose of service 

roads is to provide maintenance crews access to the transmission lines. These roads 

would not exist if the transmission lines did not exist. In contrast, access roads serve a 

broader purpose, such as contributing to the federal, county, or state road systems. 

Access roads provide direct or indirect access to the transmission lines, but that access 

is not their primary purpose. The Proponents are responsible for the reclamation of 

service roads following abandonment and in accordance with the landowner’s direction, 

but are not responsible for reclamation of access roads unless mutually agreed upon by 

the Proponents and the landowner or required by the land management agency. 

Service roads would be decommissioned following removal of the structures and lines 

and may be decommissioned while the lines are in-service if they are determined to no 

longer be necessary. 

The Proponents may decommission service roads by 1) entering into an agreement with 

the BLM or Forest Service under which the agencies restore the road located on federal 

lands and are reimbursed for costs by the Proponents, or 2) the Proponents or their 

contractor implement restoration measures as described below. 

When a service road has been identified as no longer necessary, the road will be 

reclaimed and seeded as soon as possible during the optimal seeding season. In some 

cases, reseeding may not be necessary, given the existing amount of soil compaction 

and vegetation currently in place. Where required by the land management agency, 

compacted areas would be ripped and appropriate sediment control measures would be 

implemented. 

The seed mix used for any restoration and revegetation project would be determined in 

consultation with the landowner or land management agency. All seed and plant 

material used on federal lands would be approved by the land management agency. All 

seed would meet all of the requirements of the Federal Seed Act and applicable Idaho 

and Wyoming laws regarding seeds and noxious weeds. Only seed certified as 

“noxious weed free” would be used. If requested, the Proponents or their contractor 
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would provide the landowner with evidence of seed certification. Any seed mixture 

would not contain aggressive, non-native species that might invade the site. Where 

necessary, the surface of the ground would be prepared prior to seeding. Where 

practical, the Proponents would follow these guidelines for preparing the seedbed: 

1. The road surface would be cleared of foreign materials, such as garbage, paper, 

and other materials, but all rocks, limbs, or minor woody debris would be left in 

place. The Proponents or their contractor would prepare the seedbed 

immediately prior to seeding. 

2. Under favorable soil-moisture conditions, a standard disk or spring bar harrow 

would be used (where ripping is not required) to roughen the topsoil layer to 

create the desired surface texture before the seed is applied. Dirt clods and 

chiseled voids resulting from the roughening process increase the surface area 

for water collection and provide microsites for seed establishment. The soil 

should be disked or harrowed to no more than 2 inches deep at a time when soil 

moisture allows the surface to remain rough, with clods approximately 2 to 

4 inches in diameter. 

3. Ripping, disking, or harrowing would be performed parallel to surface contours. 

In this way, downslope alignment of furrows can be avoided. In areas that 

already have the desired soil characteristics, the seedbed does not need to be 

prepared. 

After the seedbed has been prepared, the Proponents or their contractor would 

broadcast the seed on the disturbed area, after which the seed would be lightly 

harrowed into the roadbed or raked into the ground. Mulch and fertilizers would be 

added if necessary. An area would not be seeded when wind velocities prohibit the 

seed mix from being applied evenly. If the seed does not germinate and establish to an 

agreed-upon level of vegetation cover (e.g., consistent with adjacent site conditions) 

after two growing seasons, the Proponents or their contractor would reseed during a 

period acceptable to the landowner. On NFS lands, the Proponents would be 

responsible for monitoring the effectiveness of soil protection and restoration measures 

and would take corrective measures as needed to ensure long-term soil protection. 

Other seeding methods, such as drilling, hydroseeding, or aerial application, may be 

used depending on the area that requires reclamation and site conditions.