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POWER ENGINEERS, INC.
STL 085-2544 (SR-02) PAWNEE-DANIELS PARK REV 2 (02/14/2014) RP
131199
February 14, 2014
XCEL ENERGY
Pawnee to Daniels Park
345 kV Project Underground Feasibility Study
PROJECT NUMBER: 131199
PROJECT CONTACT: LES HINZMAN RYAN PARKER EMAIL:
[email protected] [email protected] PHONE:
1-208-788-0577 1-314-851-4091
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POWER ENGINEERS, INC.
STL 085-2544 (SR-02) PAWNEE-DANIELS PARK REV 2 (02/14/2014) RP
131199
Underground Report
PREPARED FOR: XCEL ENERGY PREPARED BY: RYAN PARKER
(314) 851-4091 [email protected]
LES HINZMAN (208) 788-0577
[email protected]
REVISION HISTORY
DATE REVISED BY REVISION
10/08/13 1st Draft Issued for Review
11/06/13 Ryan Parker Issued as Final
2/14/14 Ryan Parker Issued as Final
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TABLE OF CONTENTS
0.0 EXECUTIVE SUMMARY
......................................................................................................
1
1.0 PROJECT DESCRIPTION
.....................................................................................................
2
1.1 XLPE CABLE SYSTEM DESIGN
...............................................................................................
2 1.1.1 System Description and Trench Design
.........................................................................
2
1.2 AMPACITY STUDIES
................................................................................................................
4 1.2.1 Ampacity Calculations
...................................................................................................
4
1.3 ELECTROMAGNETIC FIELDS
...................................................................................................
5
2.0 UNDERGROUND CABLE SYSTEMS
..................................................................................
7
2.1 RELIABILITY OF 345 KV CABLE SYSTEMS
.............................................................................
7 2.2 EXTRUDED DIELECTRIC CABLE SYSTEMS
..............................................................................
7
2.2.1 Cable
...............................................................................................................................
7 2.2.2 Cable Accessories
...........................................................................................................
9 2.3.3 Civil Installation
.............................................................................................................
9 2.3.4 Vault Design and Installation
.......................................................................................
10 2.3.5 Cable Maintenance and Repair
.....................................................................................
11 2.3.6 Pros and Cons
...............................................................................................................
11
2.5 TRENCHLESS INSTALLATIONS
..............................................................................................
12
3.0 TERMINATIONS
..................................................................................................................
13
3.1 DESCRIPTION
........................................................................................................................
13 3.1.1 Termination Structure
...................................................................................................
13 3.1.2 Transition Station
.........................................................................................................
13
4.0 COST ESTIMATE
.................................................................................................................
14
4.1 COST ESTIMATE ASSUMPTIONS
............................................................................................
14 4.2 SUMMARY OF COST ESTIMATES
...........................................................................................
15
5.0 COMPARISON OF ENVIRONMENTAL IMPACTS OF OVERHEAD AND
UNDERGROUND TRANSMISSION LINE CONSTRUCTION
.................................................. 17
5.1 RIGHT OF WAY WIDTHS
.......................................................................................................
17 5.2 GROUND DISTURBANCE
.......................................................................................................
17 5.3 LAND USE AND AESTHETICS
................................................................................................
18 5.4 ELECTRIC FIELDS, MAGNETIC FIELDS, AND NOISE
..............................................................
18 5.5 RIGHT OF WAY CLEARING AND VEGETATION CONTROL
..................................................... 18 5.6
EROSION CONTROL IN UNSTABLE AREAS
............................................................................
19
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APPENDICES
APPENDIX A – AERIAL MAP
APPENDIX B – AMPACITY STUDIES
APPENDIX C – EMF CALCULATIONS
APPENDIX D – TRENCH DETAILS
APPENDIX E – VAULT DETAILS
APPENDIX F – COST ESTIMATES
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131199 PAGE 1
0.0 EXECUTIVE SUMMARY Xcel Energy (Xcel) is evaluating the
feasibility of undergrounding portions of a new double circuit 345
kV transmission line to be located southeast of Denver, Colorado.
The proposed hybrid overhead and underground 345 kV circuits would
serve as inner transmission tie lines for the existing 345 kV
transmission ring around Denver. Several substations would be
included in this scenario; however, the interconnection of Sulphur
Substation to IREA Parker Substation is the primary candidate being
considered for an underground installation due to urban congestion.
As part of this evaluation, Xcel has requested that POWER
Engineers, Inc. (POWER) evaluate the associated costs and technical
feasibility for installing new extruded dielectric cables within a
manhole and duct bank system in the existing overhead transmission
easement between Sulphur and IREA Parker substations. An additional
estimate will also be included for a typical 1-mile underground
cable installation in a developed residential area within the
210-foot easement. POWER performed ampacity calculations for
various underground line configurations to estimate preliminary
cable sizing requirements for this installation. Based on these
calculations, POWER concluded that three cables per phase would
meet the 1,733 MVA rating requirement for the new 345 kV lines.
Only the XLPE cable system was evaluated for these underground
transmission lines. The estimated installation costs for the XLPE
insulated cable systems for the transmission lines from Sulphur
Substation to IREA Parker Substation and the typical 1-mile 345 kV
underground lines through a developed residential area are as
follows.
Description Length (miles)
Material Labor Other* Total
Sulphur Substation to IREA Parker
1.4 $25,371,514 $10,668,513 $14,714,989 $50,755,016
1-mile Developed Residential Installation 1 $15,439,563
$6,283,513 $8,813,243 $30,536,318
Table 0-1: Cost Summary
* Other costs include additional expenditures for contingencies,
overheads, AFUDC, escalation, etc.
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1.0 PROJECT DESCRIPTION POWER Engineers, Inc. (POWER) prepared
this report for Xcel’s Pawnee to Daniels Park 345 kV Project. The
ampacity requirement for each circuit is 2,900 A (1,733 MVA at 345
kV). Ampacity calculations were performed to estimate the cable
conductor size required to reach the desired ampacity. The results
are discussed in Section 1.2 of this report. Electromagnetic field
(EMF) calculations were completed based on the probable loading of
the cables to determine the EMF intensity of the proposed system.
These results are discussed in Section 1.3 of this report. This
report describes and summarizes:
Preliminary cable system design options; Cost estimates for the
two pre-selected routes; and Environmental effect of overhead and
underground construction
Appendix A contains an aerial route map for the underground
transmission lines to be considered Appendix B contains ampacity
studies Appendix C contains EMF calculations Appendix D contains
typical trench details Appendix E contains termination and vault
details Appendix F contains cost estimates for the procurement and
installation of the cable system 1.1 XLPE Cable System Design POWER
reviewed two duct bank configurations for the proposed installation
to include placing both circuits in the same duct bank and
installing each circuit in a separate duct bank. Due to the large
ampacity requirement for each circuit, it was determined that the
most cost effective and practical design would be to install each
circuit in its own duct bank and trench. Based on the results of
the ampacity study, an underground 345 kV XLPE cable system would
consist of three cables per phase for each circuit. The cable would
utilize a 3500 kcmil segmented copper conductor with one cable
installed in an individual duct. A minimum of 20 feet would be
required between the duct banks of each circuit to eliminate mutual
heating impacts between the two circuits. A general discussion of
XLPE cable systems and installation methods is provided in Section
2. 1.1.1 System Description and Trench Design Both routes selected
for this study share the same trench design. For each circuit, the
cable system would consist of three cables per phase, installed
within polyvinyl chloride (PVC) conduits encased in a 4 feet H x 5
feet W concrete duct bank. The concrete would have a compressive
strength of 3000 psi. The duct bank would consist of multiple
conduits for the XLPE transmission line cables, the
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grounding cables, and the fiber-optic cables. The duct bank
would be installed at a minimum 36 inches cover depth. The cable
system and trench details are as follows:
High Voltage, Extruded Dielectric Cable o 3500 kcmil segmented
copper o Extruded cross-linked polyethylene solid dielectric
insulation o Lead, aluminum, or copper sheath to serve as the cable
shield and metallic moisture
barrier o Protective jacket
Open Cut Trenching o Mechanical excavation of concrete/asphalt
(for roadways), top soil or sub-grade
material o 3 cables per phase duct banks
Two (2) ductbanks separated by 20 feet edge to edge Approximate
individual dimensions of 4 feet tall by 5 feet wide Minimum depth
below grade of 36 inches Concrete encased ductbank
Twelve (12) eight-inch (8”) PVC conduits for the power cables
Three (3) 2” PVC conduits for ground continuity conductors One (1)
two-inch (2”) PVC conduit for temperature monitoring Two (2)
four-inch (4”) PVC conduits for communications
o Splicing manholes Approximate dimensions are 8 feet wide by 30
feet long by 8 feet tall Pre-cast design Premolded cable
splices
Trenchless Designs (1.4 mile route only) o Jack and bore
required under Highway 83 o One bore per circuit
Length: 200 feet Depth: 20 feet Casing: 54 inch HOBAS ®
Cable Terminations o Steel structures and concrete foundations
at each substation o 18 terminations and 18 arresters o Grounding
system for each structure
System Communications and Monitoring o Fiber optic communication
cables o Fiber optic temperature monitoring system for cable
The final duct bank size and layout would be determined during
detailed design and would be based on Xcel’s completed design
criteria. Factors to be considered during detailed design are
electrical requirements, heat dissipation, minimal burial depths,
existing facility/utility locations, and cable installation
requirements. Drawing D-1 in Appendix D shows a typical trench
cross section for an XLPE duct bank configuration.
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1.2 Ampacity Studies POWER performed preliminary cable ampacity
calculations for the XLPE cable system. The primary purpose of the
ampacity calculations was to determine a minimum conductor size,
number of cables and cable system configuration based on the design
requirements provided by Xcel Energy. 1.2.1 Ampacity Calculations
POWER used CYME International’s Cable Ampacity Program (CAP) to
model each of the cable systems. Each cable system was analyzed
using the following design criteria.
Voltage 345 kV Ampacity
Normal (Continuous) 2900 Amps (1,733 MVA) at 345 kV Load Factor
75% Burial Depth 10-ft max (Residential Construction)
20-ft max (Bore Depth) Thermal Resistivity (ρ, rho)
Native Soil 90°C-cm/W Encasement/Corrective Backfill 50°C-cm/W
at 5% moisture Thermal Grout 70°C-cm/W
Ambient Temperature Earth 18°C at 10-ft depth 11°C at 20-ft
depth
Maximum Conductor Operating Temperature XLPE 90°C Steady State
105°C Emergency Many factors should be considered when trying to
design the optimal and most economical underground cable system. A
critical factor of the underground cable system is the thermal
performance. Among those design parameters that must be determined
to achieve optimal thermal performance and with it maximum load
transfer are:
Cable Size – increasing the conductor size generally allows for
an increased load transfer capability. However, there is a limit to
the maximum conductor size that can be manufactured by the majority
of cable suppliers. This conductor size is typically accepted to be
3000 to 3500 kcmil, although larger conductor sizes could be
manufactured at a significant increase in cost.
Soil Thermal Resistivity – the ability to dissipate heat away
from the cable is based
on the thermal properties the native soils and the backfill
material installed around the cable duct.
Cable Depth – the deeper the cable is from grade, the harder it
is for the surrounding
soil to dissipate the heat, thus resulting in a lower
ampacity.
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Cable Separation – other energized cables in close proximity
also generate heat, thus resulting in mutual heating. Mutual
heating could be reduced further by increasing the separation of
the cables. However, the further the cables are separated, the
larger the excavation, backfill material quantities, as well as
labor, resulting in an overall increase in project costs.
Ampacity calculations were performed for two scenarios to
determine the minimum conductor size and cable system
configuration. “Pinch points”, key positions along the route that
would limit the cable ampacity, were identified and used to compare
the thermal effects between the duct bank designs. The trenchless
crossing under Highway 83 (assumed at 20 feet) and a typical
utility crossing (approximate trench depth of 10 feet) represented
the pinch points for the underground transmission line in this
study. For depths greater than 20 feet, each of the factors
described above would have to be considered, and in all cases, the
resulting installation would likely cost more. The results of the
ampacity calculations for the proposed two 345 kV circuits are
provided below. The cable system type, number of cables per phase,
installation depth, and resultant ampacity is noted. The
calculations assume a minimum separation of 20 feet between the
edges of the duct banks to eliminate the effects of mutual heating
between the two circuits.
Table 1-1: Ampacity Results
Ampacity calculations are in Appendix B. Typical trench depth
assumes a minimum of 36 inches of cover over the duct bank. Trench
detail configurations are shown in Appendix D. 1.3 Electromagnetic
Fields A common concern with the operation of transmission lines is
the magnitude of the electromagnetic fields produced by the EHV
underground cable system. Electromagnetic fields are made up of two
components – electric fields and magnetic fields. Electric fields
are produced by electric potential or voltage. Electric fields for
underground cables are generally not a concern, because they are
completely contained within the transmission cable by the metallic
shield. Magnetic fields are produced by the flow of AC electric
current. Magnetic fields are measured in Gauss (G) or Tesla (T).
The results for this study are shown in milligauss (mG).
Description Conductor Size Cables per
Phase
345 kV Insulation
Type
Burial Depth
(ft)
Total Ampacity
(A) Highway 83
Crossing 3500 kcmil 3 XLPE 20 2931
Typical Ductbank 3500 kcmil 3 XLPE 10 3570
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Any device that produces a voltage and carries electric current
will produce EMF. EMF produced by underground transmission lines
will have the greatest magnitude when measured directly above the
circuit, and the levels will diminish as the distance increases
away from the circuit. Values listed in Table 1-2 are the
calculated EMF values directly above a single circuit transmission
line. These values are calculated at 1 meter (3.28 feet) above the
ground (grade), centered over the circuit. POWER used CYME
International’s EMF calculation module to model the electromagnetic
field effects of the XLPE insulated cable system. Calculations were
perpared for each cable system based on public utility commission
(PUC) levels for the transmission circuit.
The underground calculations were based on the following general
criteria.
Distance above ground for calculations 3.28 feet (1.0 meter)
Burial depth 3 feet
Transmission currents are balanced (equal magnitude on each
phase of the circuit and the three phases are separated by 120
degrees)
Electrical loading values provided by Xcel
Proposed Loading XLPE (mG) at 1.0 m above ground directly above
the cable
Typical Loading 433 MVA 26.8 Max Conductor Loading 866 MVA 53.6
Max Circuit Loading 1733 MVA 107.0
Table 1-2 EMF Table
EMF calculations can be found in Appendix C.
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2.0 UNDERGROUND CABLE SYSTEMS There are currently two common
types of cable systems being utilized at the 345 kV voltage level,
high-pressure fluid-filled (HPFF) and cross-linked polyethylene
(XLPE). As stated in the Project Description in Section 1, only the
XLPE underground cable systems will be considered for the 345 kV
underground transmission lines for Xcel’s Pawnee to Daniels Park
Project. In this section, a description of the XLPE cable system is
presented. 2.1 Reliability of 345 kV Cable Systems In general,
underground transmission cable systems are very reliable. The main
reliability issue with an underground cable circuit compared to an
overhead circuit is the length of the outage in the event of a
circuit fault. With an overhead circuit, the line can generally be
placed back into service in a relatively short amount of time,
typically less than a day, thus increasing the circuit’s
availability for transmitting load. When there is a fault on an
underground line, the line may be out of services for a significant
amount of time, more than two weeks and up to 6 months, depending
on the type of failure and how quickly it can be located and
repaired. Because of these longer outage durations, an underground
circuit has a lower circuit availability as compared to an
equivalent overhead circuit. One common design practice used to
alleviate this problem is to have an alternative transmission line
or 100% redundancy. By implementing a design to ensure continuous
operation, the availability of underground transmission lines
increases significantly. Another design practice is to use multiple
cables for each of the 3 phases. This design has 3 cables/phase. If
one cable fails, it can be removed in several days. The circuit
availability would then be about 2/3 of the maximum line rating.
2.2 Extruded Dielectric Cable Systems 2.2.1 Cable The components of
a typical XLPE cable are shown in Figure 2-1. The typical cable
consists of a stranded copper or aluminum conductor, inner
semi-conducting conductor shield, extruded solid dielectric
insulation, outer semi-conducting shield, metallic moisture
barrier, and protective jacket. Insulation materials used for solid
dielectric cables include:
Thermoplastic Polyethylene (PE) Compounds
Typical thermoplastic polyethylene insulation materials are
low-density polyethylene (LDPE), high molecular weight polyethylene
(HMWPE) and high-density polyethylene (HDPE).
Thermosetting Compounds
Ethylene propylene rubber (EPR) and cross-linked polyethylene
(XLPE) are typical thermosetting insulation compounds.
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Materials used for semi-conducting extruded conductor and
insulation shields are semi-conducting PE, XLPE, and EPR compounds.
PE compounds are used with PE and XLPE insulation, XLPE compounds
with XLPE insulation, and EPR compounds with EPR insulation. Cable
jackets are typically extruded PE, and on rare occasions, polyvinyl
chloride (PVC).
Figure 2-1: Typical Extruded Dielectric Cable Cross-Section
The manufacturing process for extruded cables is of critical
importance to ensure a dependable end product. Triple extrusion,
using the “true triple head” technique, is the preferred and
recommended process of constructing the cable layers, which most
manufacturers practice today. Because microscopic voids and
contaminants lead directly to cable failures, quality control
during manufacture of extruded dielectric cables is critical to
minimize moisture contamination, voids, contaminants, and
protrusions. In conjunction with the triple extrusion process,
manufacturers minimize insulation contamination by using super
clean insulation compounds, transported and stored in sealed
facilities, while screening out all other contaminants at the
extruder head.
1 – CONDUCTOR Material: copper
2 – INNER SEMI-CONDUCTIVE SHIELD 3 – EXTRUDED SOLID DIELECTRIC
INSULATION
Material: cross-linked polyethylene
4 – OUTER SEMI-CONDUCTIVE SHIELD 5 – SEMI CONDUCTIVE
SWELLING/BEDDING
TAPES 6 – CONCENTRIC COPPER WIRE METALLIC
SHIELD 7 – SEMI CONDUCTIVE SWELLING/BEDDING
TAPES 8 – MOISTURE BARRIER
Material: copper, aluminum, lead, or stainless steel
9 – PROTECTIVE JACKET
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2.2.2 Cable Accessories The three basic cable accessories for
extruded dielectric cables are splices, terminations, and sheath
bonding materials. Pre-fabricated or pre-molded splices are
commonly used to joint extruded dielectric cables and are
recommended for a 345 kV XLPE cable system. Cable preparation for
these types of splices is generally the same. Insulation and
shields are removed from the conductor, and the insulation is
penciled. The conductor ends are then joined by a compression
splice or metal inert gas (MIG) welding (aluminum conductor only).
An advantage of these types of splices is that all parts can be
factory tested prior to field installation. Terminations are
available for extruded dielectric cable to allow transitions to
overhead lines or above ground equipment. Termination bodies are
typically made of porcelain or polymer and include skirts to
minimize the probability of external flashovers due to
contamination. Another important component of an XLPE cable system
is the grounding/bonding of the cable shield. Unlike an underground
distribution system, in which the shield is grounded at each splice
and termination, an underground transmission line requires
alternative grounding/bonding methods. Grounding at each splice and
termination causes circulating currents on the cable shield
resulting in additional heating in the cable and lower ampacity.
The way to maximize the ampacity of an underground cable is to
eliminate the circulating currents. This is accomplished with
underground transmission cables by using special bonding methods
such as single-point and cross-bonding. These methods eliminate or
reduce the amount of current that would flow on the cable shield,
resulting in no or limited additional heating and ultimately a
higher ampacity. When using one of these specialized bonding
techniques, additional equipment (link box) needs to be installed
in the cable vaults (manholes) and at the terminal ends. A link box
allows the cable shield to be connected to ground, a surge
diverter, or an adjacent cable shield. The final connection depends
on the bonding scheme used. The link box also allows the cable
shields to be isolated for routine jacket testing purposes. 2.3.3
Civil Installation There are two common types of XLPE cable system
installation. They are direct buried and concrete encased duct
banks. Even though direct buried is the most economical method for
installing an XLPE cable system, the most common method in the U.S.
is to install a concrete encased duct bank system. The reasons a
duct bank system is the preferred method are:
Provides better mechanical protection than direct buried cable.
Eliminates re-excavation in the event of a cable failure. Allows
for opening short lengths of trench for construction activities
versus the direct buried
system, which requires that the entire trench be left open for
cable installation. The most basic method for constructing an
underground duct bank is by open cut trenching. Typical
construction results in the use of mechanical excavation to remove
the concrete, asphalt road surface, topsoil and sub-grade material
to the desired depth. Removed material is relocated to an
appropriate off-site location for disposal, or occasionally reused
as backfill. Once a portion of the trench is
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opened, PVC conduit is assembled and lowered into the trench.
The area around the conduit is filled with a high strength thermal
concrete (3000 psi). After the concrete is installed, the trench is
backfilled, generally with a soil capable of thermal correction,
and the site restored. Backfill materials should be clean excavated
material, thermal sand and/or a thermal concrete mix. 2.3.4 Vault
Design and Installation Access vaults are needed periodically along
an underground route to facilitate cable installation, for
maintenance requirements, and for access for future repairs. Vaults
are typically spaced every 1,500 to 2,000 feet along the route for
XLPE cable systems. The vault size and layout is based on the type
of cable system installed. For an XLPE cable, the vault size is
determined based on the space required for cable pulling, splicing,
and supporting the cable in the vault. The standard size of each
vault would be about 8 ft wide by 28 ft long. For this project, a
vault would be needed for each set of cables, due to the number of
bends in the route and the requirement of needing multiple cables
per phase to achieve the load requirement. Placing each set of
cables in separate vaults also allows Xcel to perform maintenance
or repair on one set of cables while keeping the other energized,
and operating the circuit at a reduced line rating. The factors
contributing to the final placement of the vaults are allowable
pulling tensions, sidewall pressure on the cable as it goes around
a bend, and the maximum length of cable that can be transported on
a reel. The amount of cable that can be transported on a reel is
based on the reel’s width, height, and weight. A typical pre-cast
vault layout and configuration is shown in Appendix D.
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Figure 2-2: Typical XLPE Vault Installation
2.3.5 Cable Maintenance and Repair XLPE cable requires little
maintenance since it is usually installed in a duct bank. Duct
inspections are performed in conjunction with routine vault
inspections. Furthermore, ducts are seldom cleaned unless a new
circuit or grounding is being installed. Unless environmental
conditions dictate more inspections, a yearly vault inspection is
generally sufficient to examine the cable sheaths, protective
jackets, joint casings, cable neutrals, and general physical
condition of the vault. Terminations should also be visually
checked on a yearly basis to ensure a properly operating system.
Performing these inspections on a one-mile segment should take less
than one week for a utility crew to perform. In the unlikely event
of an electrical fault, the cable failure must be located. This
requires specialized equipment as well as a knowledgeable crew to
pinpoint the failure. The time it takes to locate the fault
location depends largely on the environmental surroundings and
access to the cable for testing. Once pinpointed, an entire section
of cable can be removed and replaced between vault sections, or the
duct bank can be opened up and an experienced splicing crew can
rejoin the cable ends. The amount of time the system is down
depends entirely on the fault location and the repair method that
provides the most advantageous solution. Typical repair time can
range from two to four weeks. 2.3.6 Advantages and Disadvantages
The pros and cons of XLPE cable systems for use in high voltage
applications are:
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Advantages: Essentially no operation and maintenance
requirements Appropriate reliability reported for systems of modern
design at voltages of 230 kV and below in
Japan, the U.S. and European countries. Extensive use and
success at 400 kV in France and Japan Higher normal operating and
short circuit temperature ratings as compared to HPFF systems
Installation environmental condition requirements for splicing and
terminating are less stringent Shorter time required for repair
Dielectric losses for extruded cable systems considerably less than
paper insulated cable systems Less specialized installation
equipment required Disadvantages: Susceptible to damage from
dig-ins, if direct buried Potential for induced sheath voltages and
losses Trench for installation of entire cable length (direct
buried) must be left open during cable
installation Duct bank/conduit installation reduces thermal
performance and increases cost XLPE insulation not forgiving
Limited splicing/terminating workforce in U.S 2.5 Trenchless
Installations Trenchless civil installation techniques have been
developed for crossing environmentally sensitive areas and major
obstructions such as waterways, wetlands, highways, and railroads.
Three trenchless methods have commonly been used for installing
underground transmission facilities. These methods are:
Jack and Bore Horizontal Directional Drilling
Micro-tunneling
For the 1.4 mile 345 kV underground installation from IREA
Parker to Sulphur Springs Substation, it is assumed that there
would be a required trenchless installation to cross beneath
Highway 83. The jack and bore method would be used to cross under
Highway 83 between the two substations; separate borings would be
performed for each 345 kV circuit. The required borings were
estimated using a 54-inch HOBAS pipe casing at a depth of 20-feet
below grade on the eastern side of Highway 83. The anticipated
depth of the bore was determined based on the significant elevation
change from the east side of the highway to the west. Further
analysis and conceptual design work would be required to perform a
cable system study for incorporating any additional trenchless
installations.
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3.0 TERMINATIONS The XLPE underground transmission circuits
would require the construction of termination structures at the end
of each underground segment. Structures would support cable
terminations, lightning arresters, and dead-end hardware for
overhead conductors. This would be to transition the circuits from
underground to overhead. For XLPE systems, fenced transition
stations would be required if the utility required switching and
monitoring capability. In addition, transition stations would be
required if reactive compensation were needed at the specific
transition end of the cable. Detailed reactive compensation studies
would be required to determine whether compensation would be
required. Those studies are not in the scope of this report. 3.1
Description Typical termination stations have a footprint of
approximately 250 ft by 400 ft. However, this may be a benefit as a
number of different switching arrangements can be attained, as well
as the addition of circuit protection, monitoring, and voltage
regulation. Most transition stations house an A-frame style dead
end structure with pedestal style termination structures. The XLPE
system can be converted to an overhead line in a much simpler
fashion with the use of a termination structure, because the
underground cables, as well as all of the required terminations,
can be attached directly to the structure. This has been done at
115 kV and 230 kV on the Xcel system. At 345 kV, no stand-alone
termination structure has been installed in the US. This structure
is not acceptable. For this installation, Xcel required switching
and monitoring at the cable ends, so transition stations would
still be required. The Advantages and Disadvantages of each
configuration are: 3.1.1 Termination Structure
Advantages: Disadvantages: Essentially no operation and
maintenance
requirements. High reliability Small structural footprint
Terminations can be located on structure Lower installation
cost
Can only be used for 115 kV and 230 kV XLPE cable
Failure of structure may result in prolonged outage
3.1.2 Transition Station
Advantages: Disadvantages: More switching capabilities Increased
protection capabilities/schemes SCADA can be installed in the
station Voltage regulation, if required can be incorporated Fault
Location Available
Larger structural footprint Higher cost Higher maintenance
costs
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4.0 COST ESTIMATE The cost estimate for the underground cable
system was prepared using budgetary quotations from high voltage
cable manufacturers, contractors familiar with the installation and
operation of high voltage underground cable systems, and recent
underground projects similar in nature. There are several factors
that can influence the cost of an underground system. These factors
commonly are:
Cost of material Contractor/manufacturer’s availability Cable
system location Subsurface conditions: The type and depth of soil
and rock that must be excavated to place
the cable can dramatically affect the cost. For example,
construction costs in rock formations are significantly higher than
construction costs in clay soils. The presence of existing
underground facilities also presents a significant uncertainty when
estimating the cost of an underground project.
4.1 Cost Estimate Assumptions
1) Materials used in the cost estimates meet all applicable
industry standards.
2) Construction would be performed by qualified craftsmen
experienced in installing high voltage XLPE underground
transmission systems.
3) Due to the volatility of material costs, these estimates are
subject to market fluctuations. The cable costs reflect a copper
index of $3.32/lb
4) Costs to obtain all environmental, local, state, and federal
permits and mitigation as required are not included.
5) Costs to obtain all necessary right-of-way, easement, and
property outside the limits of Xcel as required are not
included.
6) No spare cable or accessories were included in the
estimates.
7) Single point bonding of XLPE cable sheaths was assumed.
8) Mobilization and Demobilization costs were not included for
the 1-mile typical underground installation in a developed
residential area cost estimate.
9) Costs for Dewatering were not included in the estimates.
10) Rock excavation costs were not included in the cost
estimates. If rock is encountered, costs in Table 4-1 could
increase as much as 10%.
11) An overall 15% contingency was included in the cost
estimates.
12) The estimates do not include termination structures or
foundations.
13) The 1 mile estimate does not contain any costs associated
with terminal ends of the cable.
14) The 1.4-mile estimate does not contain any equipment
(including arresters) costs on the terminal end of the cable except
terminations.
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15) A system study would need to be conducted to determine the
detailed engineering and construction requirements for reactive
compensation. A study could cost from $150,000 to $300,000. For
this report, reactors are not included in the cost estimate.
4.2 Summary of Cost Estimates A summary of the costs for the
cable investigated has been included in Table 4-1 below. This
includes termination structures, but not transition stations.
Description Length (miles)
Material Labor Other Total
Sulphur Substation to IREA Parker
1.4 $25,371,514 $10,668,513 $14,714,989 $50,755,016
1-mile Developed Residential Installation
1 $15,439,563 $6,283,513 $8,813,243 $30,536,318
Table 4-1: Cost Summary* Table, Excluding Transition
Stations
4.3 Schedule There are four main parts to the project schedule:
engineering design and completion of construction documents,
material procurement, civil construction and electrical
construction. The timeline for engineering design and completion of
construction documents is primarily a function of route length and
complexity of the route alignment (terrain, road construction,
trenchless construction, etc). Material procurement is based on how
quickly suppliers can supply the construction materials needed.
Long lead-time items are cable and accessories,
transition/termination structures and manholes. The civil
construction is dependent upon a number of things such as: number
of crews being utilized for installation, type of construction
(rural, urban, etc) and type of installation (trench vs.
trenchless). Number of pulling and splicing crews is the principal
variable in electrical construction. Major assumptions made for
high level conceptual timelines are:
Durations are based on a linear approach to construction. If
multiple resources (contractors, crews, etc) are utilized, the
overall project schedule could be reduced significantly.
Engineering, procurement, and construction activities could
overlap as appropriate to reduce total project schedule. For
instance,
o Materials could be procured once the majority of engineering
is complete. o Electrical construction could begin after a good
portion of civil construction is
complete. Electrical construction consists of a cable pulling
crew and splicing crew. Splicing would
follow behind the pulling crew and begin after the first few
sections of cable are installed.
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4.4 Summary of Schedule The durations for engineering,
procurement, and construction activities required for each option
are shown in Table 4-2 below.
Route ROW Total Length (miles)
Engineering Design (months)
Material Procurement (months)
Civil Construction (months)
Electrical Construction (months)
Sulphur Substation to IREA Parker
1.4 6 10-12 9 12
Developed Residential Underground
1 6 10-12 8 10 Table 4-2 Schedule Summaries
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5.0 COMPARISON OF ENVIRONMENTAL IMPACTS OF OVERHEAD AND
UNDERGROUND TRANSMISSION LINE CONSTRUCTION The environmental impact
of underground transmission line construction differs substantially
from overhead transmission. Different right of way/easement
requirements would also apply depending on the type of underground
cable system installed. A separation between the two circuits means
that they could be installed on either combined or separate right
of ways. Temporary easements may be required if the construction
activities expand beyond existing rights of way, or if there is
insufficient room available for the set up of the installation
equipment. 5.1 Right of Way Widths Underground right of way widths
can be limited to the area containing the cable system with buffer
area on each side of the centerline, which would serve as
additional protection from unintentional excavation damage as well
as to provide access for maintenance activities. Typically, a cable
system of this magnitude would require a combined 55-foot permanent
easement when crossing private land using open trenching
techniques. This would allow the two circuits to be installed a
minimum of 10 feet from each right of way edge, and still maintain
a separation of 20 feet from the edge of each duct bank. Xcel has
an existing easement 210 feet in width that would be used for the
installation of a double circuit 345 kV cable system. Although
there is also existing double circuit 230 kV overhead transmission
infrastructure within this easement, there remains sufficient room
to construct the underground lines. 5.2 Ground Disturbance Most
ground disturbance during overhead construction occurs at the
structure locations. Underground construction involves extensive
ground disturbance including trenching along the entire line length
and the installation of splicing and pull-through vaults as
necessary. Sensitive features such as streams, rivers, and wetlands
may exist in the line route. While overhead construction has the
flexibility to span many such features, underground construction
does not. Underground transmission line installation requires
construction through these sensitive features as they are crossed
by the line route. Directional drilling or boring may be required
for underground construction in order to minimize impacts to
streams, rivers, and wetlands. However, where directional drilling
is not feasible, trenching through sensitive areas may be required
for underground construction. Underground construction requires
extensive coordination with other underground utilities to avoid
damage during construction. This level of coordination usually
exceeds that necessary for overhead construction. The potential to
disrupt or damage underground utilities is almost always greater
with underground construction.
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Replacement or restoration activities may mean additional ground
disturbance for underground lines. Overhead repair work usually
involves light impact at the structure locations. Secondary
off-site ground-disturbing impacts may be required for underground
lines if selective fill is required for thermal mitigation. The
source sites for these thermal backfills are excavated to obtain
this select fill material. 5.3 Land Use and Aesthetics Overhead
construction can be considered intrusive in visually sensitive
environments. Urban underground construction, if properly
rehabilitated, typically has lower visual impacts than overhead
construction. However, in rural areas underground routes are not
without visual impacts due to the clearing required for the
corridor. Overhead construction may not be suitable for congested
urban areas and generally impact urban land use more than
underground construction. In rural settings, underground
construction can be much more disruptive to agricultural or rural
land uses than overhead construction. Underground construction
would require that disturbed vegetated areas be restored to
preconstruction conditions, however, large trees would not be
allowed within 15 feet of the duct bank. Traditional farming
operations are usually permitted along the underground route.
Underground vaults would require the same separation guidelines as
an overhead structure foundation. 5.4 Electric Fields, Magnetic
Fields, and Noise Underground construction in pipes or shielded
cable eliminates electrical fields at the right of way boundary.
Magnetic fields are generally higher directly over an underground
installation when compared to an overhead installation due to the
relative close proximity of the conductor, although magnetic fields
tend to decrease more rapidly with distance for underground
installations as compared to overhead. Details of the underground
magnetic field calculations can be found in Section 2.0 and in
Appendix B. Overhead lines can emit a hiss or low hum due to corona
discharge during rainstorms or humid periods. Underground lines are
silent for the most part, with the exception of the immediate area
near termination points. 5.5 Right of Way Clearing and Vegetation
Control In undeveloped areas, underground construction requires the
right of way, both temporary and permanent easements, to be totally
cleared to allow for construction and the establishment of the
right of way. This includes trees, brush, and ground cover. While
low growing vegetation can be reestablished over an underground
installation, trees or plants with woody roots should not be
allowed to grow over the line. Overhead construction typically
requires complete clearing only in the area of the structures and
removal of trees along the line route to provide for electrical
clearance and maintenance. Lower vegetation such as brush, shrubs,
and ground covers are often time left so long as it will not
interfere
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with maintenance and access to the line. Both underground and
overhead construction techniques generally require long-term
vegetation control in the right of way. 5.6 Erosion Control in
Unstable Areas Extensive erosion control measures are required for
underground lines as ground disturbance extends over the entire
line length with the right of way totally cleared. In areas with
hilly terrain and erosive soils, significant erosion and
sedimentation impacts can arise from underground construction. Due
to less ground disturbing activity, overhead lines usually result
in lesser erosion impacts. Careful placement of structure locations
or engineered foundation arrangements can avoid or mitigate
unstable geology or soils during overhead construction. Underground
construction usually does not have the flexibility to avoid such
areas encountered by the line route; thus, the potential for
impacts to those areas increase.
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APPENDIX A Aerial Map
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APPENDIX B Ampacity Studies
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APPENDIX C EMF Calculations
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APPENDIX D Trench Details
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APPENDIX E Termination and Vault Details
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APPENDIX F Cost Estimates
-
CYMCAP 6.1 rev. 1
Study: Pawnee-Daniels Park 345 kV
Execution: Case 1 - 3500 kcmil - 1.0 mile general case
Summary Results
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
Date: 9/24/2013
Frequency: 60 Hz
Conductor Resistances: Calculated
Fraction of conductor current returningthrough sheath for single
phase cables: 0
Value18
0.9
No. Name X Center Y Center Width Height
Thermal Resistivity [°C.m/W]
Installation Type: Multiple Duct Banks Backfills
Parameter UnitAmbient Soil Temperature at Installation Depth
°C
Thermal Resistivity of Native Soil C.m/W
Layers Dimensions [ft]Type
1 DB 3X4 -12.521 11.995 5.042 3.99 0.5
2 DB 3X4 12.521 11.995 5.042 3.99 0.5
Standard ductbank
Standard ductbank
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
-
Load Factor Temperature Ampacity
X[ft] Y[ft] [p.u.] [°C] [A]
Summary Results
Solution converged
Cable\Cable type no Circuit Phase
Location
1 \ 1
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
1 A -14.474 10.817 0.75 82.4 1190
1 B -13.172 10.817 0.75 85.4 1190
1 C -11.87 10.817 0.75 83 1190
1 A -13.172 12.119 0.75 89.9 1190
1 B -11.87 12.119 0.75 87.2 1190
1 C -14.474 12.119 0.75 86.6 1190
1 A -11 87 13 422 0 75 85 9 1190
6 \ 1
1 \ 1
2 \ 1
3 \ 1
4 \ 1
5 \ 1
7 \ 1 1 A -11.87 13.422 0.75 85.9 1190
1 B -14.474 13.422 0.75 85.2 1190
1 C -13.172 13.422 0.75 88.3 1190
2 A 10.568 10.817 0.75 83.2 1190
2 B 11.87 10.817 0.75 85.4 1190
2 C 13.172 10.817 0.75 82.1 1190
2 A 13.172 13.422 0.75 85 1190
7 \ 1
8 \ 1
9 \ 1
10 \ 1
11 \ 1
12 \ 1
13 \ 1
2 B 13.172 12.119 0.75 86.3 1190
2 C 10.568 12.119 0.75 87.5 1190
2 A 11.87 12.119 0.75 89.9 1190
2 B 10.568 13.422 0.75 86.1 1190
2 C 11.87 13.422 0.75 88.3 119018 \ 1
14 \ 1
15 \ 1
16 \ 1
17 \ 1
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
-
CYMCAP 6.1 rev. 1
Study: Pawnee-Daniels Park 345 kV
Execution: Case 2 - 3500 kcmil - 1.4 mile HDD case
Summary Results
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
Date: 9/19/2013
Frequency: 60 Hz
Conductor Resistances: Calculated
Fraction of conductor current returningthrough sheath for single
phase cables: 0
Value11
0.9
No. Name X Center Y Center Width Height
Thermal Resistivity [°C.m/W]
Installation Type: Multiple Duct Banks Backfills
Parameter UnitAmbient Soil Temperature at Installation Depth
°C
Thermal Resistivity of Native Soil C.m/W
Layers Dimensions [ft]Type
1 DB 3X4 -11.896 21.412 3.792 2.823 0.7
2 DB 3X4 11.896 21.412 3.792 2.823 0.7
Standard ductbank
Standard ductbank
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
-
Load Factor Temperature Ampacity
X[ft] Y[ft] [p.u.] [°C] [A]
Summary Results
Solution converged
Cable\Cable type no Circuit Phase
Location
1 \ 1
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
1 A -13.349 20.567 0.75 83.9 977
1 B -11.412 20.567 0.75 84.7 977
1 C -12.38 20.567 0.75 86.7 977
1 A -12.38 21.536 0.75 90 977
1 B -13.349 21.536 0.75 86.9 977
1 C -11.412 21.536 0.75 87.7 977
1 A -11 412 22 505 0 75 85 9 977
6 \ 1
1 \ 1
2 \ 1
3 \ 1
4 \ 1
5 \ 1
7 \ 1 1 A -11.412 22.505 0.75 85.9 977
1 B -12.38 22.505 0.75 87.9 977
1 C -13.349 22.505 0.75 85 977
2 A 10.443 20.567 0.75 84.8 977
2 B 12.38 20.567 0.75 83.7 977
2 C 11.412 20.567 0.75 86.7 977
2 A 11.412 21.536 0.75 90 977
7 \ 1
8 \ 1
9 \ 1
10 \ 1
11 \ 1
12 \ 1
13 \ 1
2 B 10.443 21.536 0.75 87.8 977
2 C 12.38 21.536 0.75 86.8 977
2 A 12.38 22.505 0.75 85 977
2 B 11.412 22.505 0.75 87.9 977
2 C 10.443 22.505 0.75 86 97718 \ 1
14 \ 1
15 \ 1
16 \ 1
17 \ 1
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
-
CYMCAP 6.1 rev. 1
Study: Pawnee-Daniels Park 345 kV
Execution: Case 2 - 3500 kcmil - 1.4 mile HDD case
Date: 9/19/2013
Cables input data
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
No Unit 1
1 1
2 1
3 kV 345
4 inch2 2 7484
Description
General cable informationCable type no
Number of cores
Voltage
Conductor area4 inch2 2.7484
5 °C 90
6 °C 110
7 copper
8 u.cm 1.7241 Resistivity @20°C
Conductor area
Maximum Steady-State Conductor Temperature
Maximum Emergency Conductor Temperature
ConstructionConductor
Material
8 u.cm .7
9 1/K 0.00393
10 °C 234.5
11 J/K.m3 3.45
12 6 segments
13 No
14 0.39
y @
Temperature coefficient
Reciprocal of temperature coefficient of resistance (BETA)
Volumetric specific heat (SH)
Construction
Is cable dried?
ks (Skin effect coefficient)
15 0.37
16 inch 2.159
17 Yes
18 inch 0.067
19 inch 2.293Diameter
kp (Proximity effect coefficient)
Diameter
Conductor shield
Is layer present?
Thickness
Insulation
I l ?20 Yes
21 XLPE (unfilled)
22 K.m/w 3.5
23 0.001
24 2.3
25 inch 1.063
26 inch 4 419
Is layer present?
Material
Thermal resistivity
Dielectric loss factor - ( tan )
Relative permittivity ( )
Thickness
Diameter26 inch 4.419
27 Yes
28 semi-conducting
29 inch 0.063
30 inch 4.545
Thickness
Diameter
Insulation screen
Is layer present?
Material
Diameter
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
-
31 Yes
32 No
33 lead
34 u.cm 21.4
35 1/K 0.004
Sheath
Is layer present?
Is around each core? (Only for Three core cable)
Material
Resistivity @20°C
Temperature coefficient
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
36 °C 230
37 J/K.m3 1.45
38 Non-corrugated
39 inch 0.08
40 inch 4.705
41 Yes
Diameter
Reciprocal of temperature coefficient of resistance (BETA)
Volumetric specific heat (SH)
Corrugated construction
Thickness
Is layer present?
Jacket
41 Yes
42 polyethylene
43 K.m/w 3.5
44 inch 0.145
45 inch 4.995
46 inch 4.995
Is layer present?
Material
Thermal resistivity
Thickness
Diameter
Overall cable diameter
Diameter46 inch 4.995
No Unit 1
1 Yes
Diameter
Description/Value
SPECIFIC INSTALLATION DATABonding
Multiple cables per phase, single point bonded
2 0.3
3 Yes
4 6
5 YesSingle conductor cables NOT touching
Loss factor constant
Loss factor constant
Duct construction
PVC duct in concrete or buried
Resistivity (RH)
Cables touching
p p p g p
5 YesSingle conductor cables NOT touching
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
-
No Symbol Description Unit 1 2 3 4 5
1 Cable type no 1 1 1 1 1
2 Circuit no 1 1 1 1 1
3 Phase A B C A B
Temperature calculations
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
3 Phase A B C A B
4 c Conductor temperature °C 83.9 84.7 86.7 90 86.9
5 i Sheath/Shield temperature °C 77.8 78.6 80.6 83.9 80.8
6 j Armour/Pipe or Jacket temperature °C 77.2 78 80 83.3
80.2
7 s Exterior duct temperature °C 71.6 72.4 74.4 77.7 74.5
8 a Ambient temperature °C 11 11 11 11 11
No Symbol Description Unit 6 7 8 9 10Temperature
calculations
1 Cable type no 1 1 1 1 1
2 Circuit no 1 1 1 1 2
3 Phase C A B C A
4 c Conductor temperature °C 87.7 85.9 87.9 85 84.8
5 i Sheath/Shield temperature °C 81.6 79.8 81.7 78.9 78.7
6 j Armour/Pipe or Jacket temperature °C 81 79.3 81.2 78.4
78.1
7 s Exterior duct temperature °C 75.4 73.6 75.6 72.7 72.5
p
8 a Ambient temperature °C 11 11 11 11 11
No Symbol Description Unit 11 12 13 14 15
1 Cable type no 1 1 1 1 1
2 Circuit no 2 2 2 2 2
3 Phase B C A B C
4 c Conductor temperature °C 83.7 86.7 90 87.8 86.8
5 Sh th/Shi ld t t °C 77 7 80 5 83 8 81 7 80 6
Temperature calculations
5 i Sheath/Shield temperature °C 77.7 80.5 83.8 81.7 80.6
6 j Armour/Pipe or Jacket temperature °C 77.1 80 83.3 81.1
80.1
7 s Exterior duct temperature °C 71.5 74.3 77.7 75.5 74.4
8 a Ambient temperature °C 11 11 11 11 11
No Symbol Description Unit 16 17 18
1 Cable type no 1 1 1
2 Circuit no 2 2 2
Temperature calculations
2 Circuit no 2 2 2
3 Phase A B C
4 c Conductor temperature °C 85 87.9 86
5 i Sheath/Shield temperature °C 78.9 81.7 79.9
6 j Armour/Pipe or Jacket temperature °C 78.3 81.2 79.3
7 s Exterior duct temperature °C 72.7 75.5 73.7
8 a Ambient temperature °C 11 11 11
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
-
Cable type no: 1
Cable type: OTHER
Cable ID: 345C3.50X
Cable title: 345 kV 3500 kcmil CU XLPE Xcel Energy
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
STL 085‐2554 (SR‐02) 131199 (10/08/13) REV 0 Appendix B
-
Client: Xcel Energy Prepared By: Travis HettwerProject Name:
Pawnee-Daniels Park 345-kV Date: 9/26/2013Project Number: 131199
Checked By: Ryan Parker
Date: 9/27/2013Input Data
Graph Title:Number of Circuits:Calculation Height Above Ground:
3.28 ftDuctbank Depth: 3 ftDuctbank Separation: 20 ftBonding
Method:Current Magnitude & Angle:
Circuit Current Phasor Circuit Current Phasor1A 242 0 2A 242 01B
242 -120 2B 242 -1201C 242 120 2C 242 120
~725 A/ckt ~725 A/ckt
Calculation Results (Based on 50 ft R/W)Distance
from Center of
ROW (feet)
Magnetic Field
Strength (mG)
Distance from
Center of ROW (feet)
Magnetic Field
Strength (mG)
Distance from
Center of ROW (feet)
Magnetic Field
Strength (mG)
Distance from
Center of ROW (feet)
Magnetic Field
Strength (mG)
‐50.0 0.3645 -25.0 5.4715 0.0 9.3130 25.0 4.3920-49.0 0.3920
-24.0 6.4547 1.0 9.6697 26.0 3.7741-48.0 0.4223 -23.0 7.6479 2.0
10.3322 27.0 3.2602-47.0 0.4559 -22.0 9.0905 3.0 11.3191 28.0
2.8312
Single Point
1 Transmission, 3 Cables per PhaseDouble Circuit, 725 A/ckt
-46.0 0.4932 -21.0 10.8202 4.0 12.6511 29.0 2.4713-45.0 0.5347
-20.0 12.8623 5.0 14.3409 30.0 2.1680-44.0 0.5811 -19.0 15.2124 6.0
16.3756 31.0 1.9110-43.0 0.6330 -18.0 17.8104 7.0 18.6916 32.0
1.6922-42.0 0.6913 -17.0 20.5119 8.0 21.1448 33.0 1.5050-41.0
0.7571 -16.0 23.0730 9.0 23.4933 34.0 1.3440-40.0 0.8314 -15.0
25.1712 10.0 25.4145 35.0 1.2049-39.0 0.9159 -14.0 26.4812 11.0
26.5769 36.0 1.0843-38.0 1.0122 ‐13.0 26.7836 12.0 26.7466 37.0
0.9791-37.0 1.1225 -12.0 26.0498 13.0 25.8770 38.0 0.8871-36.0
1.2492 -11.0 24.4510 14.0 24.1222 39.0 0.8062-35.0 1.3956 -10.0
22.2871 15.0 21.7716 40.0 0.7349-34.0 1.5655 -9.0 19.8842 16.0
19.1477 41.0 0.6717-33.0 1.7635 -8.0 17.5131 17.0 16.5213 42.0
0.6157-32.0 1.9955 -7.0 15.3547 18.0 14.0738 43.0 0.5657-31.0
2.2689 -6.0 13.5049 19.0 11.8995 44.0 0.5210-30.0 2.5925 -5.0
11.9988 20.0 10.0276 45.0 0.4809-29.0 2.9777 -4.0 10.8362 21.0
8.4480 46.0 0.4449-28.0 3.4385 -3.0 10.0019 22.0 7.1310 47.0
0.4124-27.0 3.9925 -2.0 9.4777 23.0 6.0398 48.0 0.3830-26.0 4.6613
-1.0 9.2500 24.0 5.1378 49.0 0.3564
50.0 0.3322
STL 085-2554 (SR-02) 131199 (10/08/13) REV 0 EMF Calculation
(725 A) Appendix C
-
15
20
25
30
etic
Fie
ld S
tren
gth
(mG
)Pawnee-Daniels Park 345-kV
Double Circuit, 725 A/ckt
STL 085-2554 (SR-02) 131199 (10/08/13) REV 0 EMF Calculation
(725 A)
APPENDIX C
0
5
10
-60 -40 -20 0 20 40 60
Mag
ne
Distance from Center of Ductbanks (feet)
-
Client: Xcel Energy Prepared By: Travis HettwerProject Name:
Pawnee-Daniels Park 345-kV Date: 9/26/2013Project Number: 131199
Checked By: Ryan Parker
Date: 9/27/2013Input Data
Graph Title:Number of Circuits:Calculation Height Above Ground:
3.28 ftDuctbank Depth: 3 ftDuctbank Separation: 20 ftBonding
Method:Current Magnitude & Angle:
Circuit Current Phasor Circuit Current Phasor1A 484 0 2A 484 01B
484 -120 2B 484 -1201C 484 120 2C 484 120
~1450 A/ckt ~1450 A/ckt
Calculation Results (Based on 50 ft R/W)Distance
from Center of
ROW (feet)
Magnetic Field
Strength (mG)
Distance from Center
of ROW (feet)
Magnetic Field
Strength (mG)
Distance from
Center of ROW (feet)
Magnetic Field
Strength (mG)
Distance from
Center of ROW (feet)
Magnetic Field
Strength (mG)
‐50.0 0.7291 -25.0 10.9429 0.0 18.6260 25.0 8.7841-49.0 0.7840
-24.0 12.9095 1.0 19.3395 26.0 7.5481-48.0 0.8447 -23.0 15.2957 2.0
20.6644 27.0 6.5204-47.0 0.9119 -22.0 18.1809 3.0 22.6382 28.0
5.6624
Single Point
1 Transmission, 3 Cables per PhaseDouble Circuit, 1450 A/ckt
47.0 0.9119 22.0 18.1809 3.0 22.6382 28.0 5.6624-46.0 0.9865
-21.0 21.6403 4.0 25.3023 29.0 4.9427-45.0 1.0695 -20.0 25.7247 5.0
28.6818 30.0 4.3360-44.0 1.1622 -19.0 30.4249 6.0 32.7513 31.0
3.8220-43.0 1.2660 -18.0 35.6208 7.0 37.3832 32.0 3.3844-42.0
1.3826 -17.0 41.0239 8.0 42.2896 33.0 3.0099-41.0 1.5141 -16.0
46.1460 9.0 46.9865 34.0 2.6880-40.0 1.6629 -15.0 50.3425 10.0
50.8291 35.0 2.4099-39.0 1.8318 -14.0 52.9625 11.0 53.1537 36.0
2.1685-38.0 2.0244 ‐13.0 53.5671 12.0 53.4932 37.0 1.9582-37.0
2.2449 -12.0 52.0996 13.0 51.7540 38.0 1.7741-36.0 2.4984 -11.0
48.9020 14.0 48.2444 39.0 1.6124-35.0 2.7912 -10.0 44.5742 15.0
43.5433 40.0 1.4697-34.0 3.1309 -9.0 39.7684 16.0 38.2953 41.0
1.3435-33.0 3.5270 -8.0 35.0263 17.0 33.0425 42.0 1.2313-32.0
3.9911 -7.0 30.7094 18.0 28.1477 43.0 1.1314-31.0 4.5377 -6.0
27.0098 19.0 23.7990 44.0 1.0420-30.0 5.1850 -5.0 23.9976 20.0
20.0552 45.0 0.9619-29.0 5.9554 -4.0 21.6725 21.0 16.8961 46.0
0.8898-28.0 6.8771 -3.0 20.0038 22.0 14.2620 47.0 0.8248-27.0
7.9850 -2.0 18.9554 23.0 12.0796 48.0 0.7661-26.0 9.3226 -1.0
18.5000 24.0 10.2757 49.0 0.7129
50.0 0.6645
STL 085-2554 (SR-02) 131199 (10/08/13) REV 0 EMF Calculation
(1450 A) APPENDIX C
-
30
40
50
60
etic
Fie
ld S
tren
gth
(mG
)Pawnee-Daniels Park 345-kV
Double Circuit, 1450 A/ckt
STL 085-2554 (SR-02) 131199 (10/08/13) REV 0 EMF Calculation
(1450 A)
APPENDIX C
0
10
20
-60 -40 -20 0 20 40 60
Mag
ne
Distance from Center of Ductbanks (feet)
-
Client: Xcel Energy Prepared By: Travis HettwerProject Name:
Pawnee-Daniels Park 345-kV Date: 9/26/2013Project Number: 131199
Checked By: Ryan Parker
Date: 9/27/2013Input Data
Graph Title:Number of Circuits:Calculation Height Above Ground:
3.28 ftDuctbank Depth: 3 ftDuctbank Separation: 20 ftBonding
Method:Current Magnitude & Angle:
Circuit Current Phasor Circuit Current Phasor1A 967 0 2A 967 01B
967 -120 2B 967 -1201C 967 120 2C 967 120
~2900 A/ckt ~2900 A/ckt
Calculation Results (Based on 50 ft R/W)Distance
from Center of
Ductbanks(feet)
Magnetic Field
Strength (mG)
Distance from
Center of Ductbanks(
feet)
Magnetic Field
Strength (mG)
Distance from
Center of Ductbanks
(feet)
Magnetic Field
Strength (mG)
Distance from
Center of Ductbanks(
feet)
Magnetic Field
Strength (mG)
‐50.0 1.4567 -25.0 21.8632 0.0 37.2134 25.0 17.5500-49.0 1.5664
-24.0 25.7923 1.0 38.6389 26.0 15.0806-48.0 1.6877 -23.0 30.5598
2.0 41.2860 27.0 13.0274-47.0 1.8219 -22.0 36.3243 3.0 45.2296 28.0
11.3131
Single Point
1 Transmission, 3 Cables per PhaseDouble Circuit, 2900 A/ckt
-46.0 1.9709 -21.0 43.2360 4.0 50.5522 29.0 9.8752-45.0 2.1367
-20.0 51.3962 5.0 57.3044 30.0 8.6630-44.0 2.3219 -19.0 60.7869 6.0
65.4349 31.0 7.6361-43.0 2.5293 -18.0 71.1680 7.0 74.6891 32.0
6.7618-42.0 2.7624 -17.0 81.9630 8.0 84.4919 33.0 6.0137-41.0
3.0251 -16.0 92.1967 9.0 93.8760 34.0 5.3704-40.0 3.3223 -15.0
100.5810 10.0 101.5532 35.0 4.8147-39.0 3.6599 -14.0 105.8156 11.0
106.1976 36.0 4.3325-38.0 4.0447 ‐13.0 107.0236 12.0 106.8760 37.0
3.9123-37.0 4.4852 -12.0 104.0916 13.0 103.4010 38.0 3.5446-36.0
4.9917 -11.0 97.7030 14.0 96.3890 39.0 3.2214-35.0 5.5767 -10.0
89.0563 15.0 86.9966 40.0 2.9364-34.0 6.2553 -9.0 79.4547 16.0
76.5115 41.0 2.6842-33.0 7.0466 -8.0 69.9802 17.0 66.0168 42.0
2.4601-32.0 7.9739 -7.0 61.3554 18.0 56.2372 43.0 2.2604-31.0
9.0661 -6.0 53.9638 19.0 47.5488 44.0 2.0818-30.0 10.3593 -5.0
47.9456 20.0 40.0690 45.0 1.9217-29.0 11.8985 -4.0 43.3002 21.0
33.7572 46.0 1.7778-28.0 13.7399 -3.0 39.9663 22.0 28.4946 47.0
1.6480-27.0 15.9535 -2.0 37.8716 23.0 24.1342 48.0 1.5306-26.0
18.6259 -1.0 36.9618 24.0 20.5301 49.0 1.4242
50.0 1.3276
STL 085-2554 (SR-02) 131199 (10/08/13) REV 0 EMF Calculation
(2900 A) Appendix C
-
60
80
100
120
etic
Fie
ld S
tren
gth
(mG
)Pawnee-Daniels Park 345-kV
Double Circuit, 2900 A/ckt
STL 085-2554 (SR-02) 131199 (10/08/13) REV 0 EMF Calculation
(2900 A) Appendix C
0
20
40
-60 -40 -20 0 20 40 60
Mag
ne
Distance from Center of Ductbanks (feet)
-
Draft
Xcel EnergyPawnee to Daniels Park 345 kV - 1 mile - Typical
Underground in Developed Residential
Prepared by: CJS3500 kcmil Cu 2 Number of Circuits Checked by:
RAP
18 Cables - 3 Cables/Phase 2 Number of Duct Banks2900 Amps 4
Number of Comm Ducts5280 feet 1 mile 24 Number of Circuits
Quantity Material Price Total Material PriceLabor &
EquipmentPriceTotal Labor
Price Total Price
96,600 $105.00 $10,143,000 $20.00 $1,932,000 $12,075,0000
$56,000.00 $0 $18,000.00 $0 $0
36 $31,000.00 $1,116,000 $15,000.00 $540,000 $1,656,00012
$8,275.00 $99,300 $3,500.00 $42,000 $141,300
0 $4,138.00 $0 $1,000.00 $0 $0220 $135.00 $29,700 $100.00
$22,000 $51,700
32,000 $8.95 $286,400 $5.00 $160,000 $446,40054 $0.00 $0
$1,500.00 $81,000 $81,000
Communication System:21,800 $2.50 $54,500 $4.00 $87,200
$141,700
2 $10,000.00 $20,000 $5,000.00 $10,000 $30,0008 $4,000.00
$32,000 $4,000.00 $32,000 $64,000
Temperature Monitoring System:10,900 $3.50 $38,150 $4.00 $43,600
$81,750
1 $4,000.00 $4,000 $3,000.00 $3,000 $7,0001 $4,000.00 $4,000
$3,000.00 $3,000 $7,000
Duct Bank and Earthwork:128,000 $9.00 $1,152,000 $8.00
$1,024,000 $2,176,000
32,000 $3.00 $96,000 $6.00 $192,000 $288,00021,400 $3.00 $64,200
$6.00 $128,400 $192,60010,700 $3.00 $32,100 $6.00 $64,200
$96,30012,800 $15.00 $192,000 $5.00 $64,000 $256,00015,430 $15.00
$231,450 $45.00 $694,350 $925,800
9,430 $25.00 $235,750 $25.00 $235,750 $471,5006,000 $125.00
$750,000 $25.00 $150,000 $900,000
12 $35,000.00 $420,000 $25,000.00 $300,000 $720,0010 $750.00 $0
$550.00 $0 $00 $275.00 $0 $50.00 $0 $00 $200.00 $0 $150.00 $0
$0
220 $25.00 $5,500 $25.00 $5,500 $11,00010,560 $25.00 $264,000
$30.00 $316,800 $580,800
1,500 $20.00 $30,000 $10.00 $15,000 $45,00050 $25.00 $1,250
$5.00 $250 $1,500
340 $25.00 $8,500 $15.00 $5,100 $13,6000 $2.50 $0 $2.50 $0
$0
517,450 $0.25 $129,363 $0.25 $129,363 $258,7254 $100.00 $400
$750.00 $3,000 $3,4000 $0.00 $0 $0 $00 $0.00 $0 $0 $0
$15,439,563 $6,283,513 $21,723,076Unallocated Costs:
15% 2,315,934 $980,228 $3,296,1621% $0 $62,835 $62,8353% $0
$188,505 $188,5050% $0 $0 $0
$3,626,159 $1,389,581 $5,015,740$21,381,656 $8,904,662
$30,286,319
$ $21,381,656 $ $8,904,662 $30,286,319
Cable clamps, eachContinuity conductor, per foot
Description
Cable and Accessories Section:
Grounding system for structures, eachGrounding system for
vaults, each
XLPE cable, per footTerminators, eachSplices, each
Jacket integrity test, cable segment
Fiber-optic cable, per footFiber-optic cable splices (incl.
Enclosures), each
Fiber-optic cable splices, eachFiber-optic cable, per foot
Communication conduit, per foot
Handholes, each
Cable conduit, per foot
Terminal equipment, each
Continuity conduit, per foot
TM conduit, per foot
Jack and bore, per foot
Excavation, no rock, including hauling, per cubic yardSoil
backfill, including hauling, per cubic yard
Conduit spacers, each
Duct encasement concrete, per cubic yardManholes, each
Total Price (should add up to Lump Sum Price)
Subtotal
SubtotalHard Dollar Overheads: Escalation,AFUDC,etc.., lot
Internal Engineering, lot
Construction Management
Mobilization, eachDemobilization, each
Contract Engineering
Contingency
Landscape restoration, per square foot
Traffic control, daysLoam and seed, per square foot
Sheeting and shoring, per footPavement repair, per square
footCurb repair, per square foot
1" steel plating, per footBore grouting, per cubic yardBore
spacer, each
Sidewalk repair, per square foot
STL 085-2554 (SR-02) 131199 (10/08/13) REV 0 Appendix F
-
Draft
Xcel EnergyPawnee to Daniels Park 345 kV - 1.4 mile - Sulphur to
IREA Parker
Prepared by: CJS3500 kcmil Cu 2 Number of Circuits Checked by:
RAP
18 Cables - 3 Cables/Phase 2 Number of Duct Banks2900 Amps 4
Number of Comm Ducts7392 feet 1.4 miles 24 Number of Circuits
Quantity Material Price Total Material PriceLabor &
EquipmentPriceTotal Labor
Price Total Price
136,700 $105.00 $14,353,500 $20.00 $2,734,000 $17,087,50036
$56,000.00 $2,016,000 $18,000.00 $648,000 $2,664,00072 $31,000.00
$2,232,000 $15,000.00 $1,080,000 $3,312,00012 $8,275.00 $99,300
$3,500.00 $42,000 $141,30012 $4,138.00 $49,656 $1,000.00 $12,000
$61,656
550 $135.00 $74,250 $100.00 $55,000 $129,25046,100 $8.95
$412,595 $5.00 $230,500 $643,095
90 $0.00 $0 $1,500.00 $135,000 $135,000
Communication System:31,500 $2.50 $78,750 $4.00 $126,000
$204,750
0 $10,000.00 $0 $5,000.00 $0 $016 $4,000.00 $64,000 $4,000.00
$64,000 $128,000
Temperature Monitoring System:15,800 $3.50 $55,300 $4.00 $63,200
$118,500
0 $4,000.00 $0 $3,000.00 $0 $02 $4,000.00 $8,000 $3,000.00
$6,000 $14,000
Duct Bank and Earthwork:179,200 $9.00 $1,612,800 $8.00
$1,433,600 $3,046,400
44,800 $3.00 $134,400 $6.00 $268,800 $403,20029,900 $3.00
$89,700 $6.00 $179,400 $269,10015,000 $3.00 $45,000 $6.00 $90,000
$135,000
Cable clamps, eachContinuity conductor, per foot
Description
Cable and Accessories Section:
Grounding system for structures, eachGrounding system for
vaults, each
XLPE cable, per footTerminators, eachSplices, each
Jacket integrity test, cable segment
Fiber-optic cable, per footFiber-optic cable splices (incl.
Enclosures), each
Fiber-optic cable splices, eachFiber-optic cable, per foot
Communication conduit, per foot
Handholes, each
Cable conduit, per foot
Terminal equipment, each
Continuity conduit, per foot
TM conduit, per foot 15,000 $3.00 $45,000 $6.00 $90,000
$135,00017,440 $15.00 $261,600 $5.00 $87,200 $348,80022,130 $15.00
$331,950 $45.00 $995,850 $1,327,80014,030 $25.00 $350,750 $25.00
$350,750 $701,500
8,100 $125.00 $1,012,500 $25.00 $202,500 $1,215,00024 $35,000.00
$840,001 $25,000.00 $600,001 $1,440,001
400 $750.00 $300,000 $550.00 $220,000 $520,00080 $275.00 $22,000
$50.00 $4,000 $26,00059 $200.00 $11,800 $150.00 $8,850 $20,650
1,870 $25.00 $46,750 $25.00 $46,750 $93,50014,390 $25.00
$359,750 $30.00 $431,700 $791,45017,290 $20.00 $345,800 $10.00
$172,900 $518,700
140 $25.00 $3,500 $5.00 $700 $4,200340 $25.00 $8,500 $15.00
$5,100 $13,600
7,200 $2.50 $18,000 $2.50 $18,000 $36,000525,050 $0.25 $131,263
$0.25 $131,263 $262,525
21 $100.00 $2,100 $750.00 $15,750 $17,8501 $0 $105,000.00
$105,000 $105,0001 $0 $105,000.00 $105,000 $105,000
$25,371,514 $10,668,813 $36,040,327Unallocated Costs:
15% $3,805,728 $1,696,342 $5,502,0701% $0 $106,688 $106,6883% $0
$320,064 $320,0642% $0 $213,376 $213,376
$2,251,505 $6,071,285 $8,322,790$31,428,747 $19,076,569
$50,505,316
$ $31,428,747 $ $19,076,569 $50,505,316
TM conduit, per foot
Jack and bore, per foot
Excavation, no rock, including hauling, per cubic yardSoil
backfill, including hauling, per cubic yard
Conduit spacers, each
Duct encasement concrete, per cubic yardManholes, each
Total Price (should add up to Lump Sum Price)
Subtotal
Subtotal
Contract EngineeringInternal Engineering
Construction Management
Mobilization, eachDemobilization, each
Hard Dollar Overheads: Escalation,AFUDC,…etc, lot
Contingency
Landscape restoration, per square foot
Traffic control, daysLoam and seed, per square foot
Sheeting and shoring, per footPavement repair, per square
footCurb repair, per square foot
1" steel plating, per footBore grouting, per cubic yardBore
spacer, each
Sidewalk repair, per square foot
STL 085-2554 (SR-02) 131199 (10/08/13) REV 0 Appendix F
-
R
PREL
IMIN
AR
Y
-
R
PREL
IMIN
AR
Y
085-2544 Xcel Pawnee-Daniels Park Underground Report Rev2
02-14-14085-2544 Xcel Pawnee-Daniels Park AppendicesEMF Case 2
Calculation (725 A)EMF Case 2 Calculation (725 A) chartEMF Case 3
Calculation (1450 A)EMF Case 3 Calculation (1450 A) chartEMF Case 4
Calculation (2900 A)EMF Case 4 Calculation (2900 A) chartAppendices
B.pdfCase 1 - 3500 kcmil - 1.0 mile general routeCase 2 - 3500
kcmil - 1.4 mile specified routeCase 2 - 3500 kcmil - 1.4 mile
specified route - cables
Binder1.pdfU3-1U3-2U3-3U3-4U3-5
345kV UG-Overhead transition site General Arrangment345kV
UG-Overhead transition site One Line345kV UG-Overhead transition
site Section View