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AGENDA
#2613
SPECIAL CITY COUNCIL MEETING
CITY OF UNIVERSITY PARK
COUNCIL CHAMBERS
TUESDAY, JUNE 27, 2006, 5:00 P.M.
4:00-5:00 P.M. WORK SESSION FOR AGENDA REVIEW
I.MAIN AGENDA
FINAL REPORT: 138kV Transmission Line – Tab I Corder
II. ITEMS FROM THE FLOOR
Anyone wishing to address an item not on the Agenda or having questions about
items on the Consent Agenda should do so at this time. Questions and comments
regarding Main Agenda items may be made when that item is addressed by the City
Council.
As authorized by Section 551.071(2) of the Texas Government Code, this meeting may be
convened into Closed Executive Session for the purpose of seeking confidential legal
advice from the City Attorney on any agenda items listed herein.
AGENDA MEMO
(6/27/06 AGENDA)
DATE:
June 22, 2006
TO:
Honorable Mayor and Council
FROM:
Robbie Corder, Assistant to the Director of Public Works
SUBJECT:
TXU Transmission Line Feasibility Study: Special Meeting June 27
ITEM:
In the summer of 2005, TXU Electric Delivery representatives informed the City of plans to
employ a contractor to locate overhead utility services and underground gas, water and sewer
lines in the alley between Stanford and Amherst. In addition to the survey work, the company
told City representatives that a second contractor would be performing soil tests at various
locations in the alley. According to the utility, both contractor efforts were needed in order to
initiate design related to the reconstruction of the electric transmission line located there.
In notifying the City of the need to upgrade the line, TXU Electric Delivery noted it was also
the company’s intention to install shielding to protect against lightning strikes to further
improve the line’s reliability. Therefore, the preliminary design for the rebuild included taller,
metal poles.
In response to concerns expressed by residents and the City, the City appointed a citizen
steering committee to work with TXU in developing rebuild alternatives for the transmission
line. Additionally, the City initiated a study with Sega, Inc. to explore the feasibility of placing
the transmission line underground, and placing all overhead utilities (i.e. telephone, cable, and
electric distribution) underground. Sega was also directed to explore above ground alternatives,
to include replacing the existing wood pole with similar wood poles.
Representatives from Sega will be in attendance to present the findings of the report to the
City Council and public. It is the City’s intention to ask the steering committee to host a
community forum to garner citizen input regarding the available options based upon the
study results from Sega. Subsequently, the steering committee will be asked to develop a
recommendation for City Council consideration.
RECOMMENDATION:
ATTACHMENTS:
3800 UNIVERSITY BOULEVARD UNIVERSITY PARK, TEXAS 75205 TELEPHONE (214) 363-1644
C:\Documents and Settings\nwilson\Local Settings\Temporary Internet Files\OLK31\AGENDAMEMO (11) (2).doc 1:36 PM 06/22/06
TABLE OF CONTENTS
Page No.
SECTION 1 INTRODUCTION 1-1
SECTION 2 EXECUTIVE SUMMARY 2-1
SECTION 3 OVERHEAD TRANSMISSION ALTERNATIVES 3-1
SECTION 4 UNDERGROUND TRANSMISSION ROUTES 4-1
SECTION 5 CONVERSION OF ALLEY AERIAL SERVICES
TO UNDERGROUND 5-1
SECTION 6 CONCLUSIONS 6-1
City of University Park, Texas - Sega Project No. 06-0069
i -
138-kV Underground Transmission Feasibility Study
SECTION 1
INTRODUCTION
INTRODUCTION
The City of University Park, Texas has contracted with Sega Inc. to provide a feasibility study for
undergrounding an existing aerial 138-kV transmission line and for undergrounding all existing aerial
utility lines. Various alternatives for replacing the line with new overhead construction as well as
installing the transmission line underground are considered.
The Sega project team met with City staff, representatives of the various entities responsible for the
affected utilities, and representatives of the Transmission Line Steering Committee in March 2006. After
discussions, this Study was developed taking into consideration input from the interested parties and the
various alternatives; then, preliminary opinions of probable cost were developed. A draft study was
prepared sent to the City for review and a discussion was held in May 2006 with City Council members,
City staff, and members of the Transmission Line Steering Committee. The Sega project team includes
utilizing the services of Power Delivery Consultants, Inc. for the underground transmission considerations
due to the highly-specialized nature of underground high-voltage systems.
This Study is intended to provide the City of University Park, Texas and the Steering Committee
information to assist in determining the alternative that fits their needs for the transmission line
replacement.
City of University Park, Texas 1 - 1 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
SECTION 2
EXECUTIVE SUMMARY
EXECUTIVE SUMMARY
This Study includes three primary sections which include determining various alternatives and opinions
of probable costs for replacing the existing Greenville - Loma Alto 138-kV transmission line with
overhead construction, placing the 138-kV transmission line underground, and placing existing overhead
electric distribution, cable TV, and telephone utilities underground along the transmission line route. The
resulting alternatives and opinions of probable costs are tabulated at the end of this summary.
The overhead transmission alternatives include replacing the transmission line with new equipment and
materials using the existing design, replacing the line with skip-span construction, replacing the line pole
for pole (two alternatives with different conductor spacing, shorter spans, and shorter poles), and
replacing the line without underbuilt electric distribution, cable TV, and telephone wires. Opinions of
probable costs are developed .
The underground transmission briefly describes the various types of underground transmission circuits,
selects the most desirable for this application, and develops opinions of probable cost for construction.
Two alternative routes are considered: Placing the line under the alley and routing it in one of the
adjacent streets. Opinions of probable costs were developed for these alternatives.
The third primary section of the Study concerns the conversion of alley aerial services to underground.
Two variations of this conversion are shown. The first places the electric distribution, cable TV, and
telephone underground in the alleys along the transmission line route. This alternative was considered to
be constructed in conjunction with the City rebuilding/replacing the sanitary sewer, water lines, and the
existing gas lines. Additional rights-of-way and easements would need to be obtained. A variation of this
places the electric distribution, cable TV, and telephone service feeds at the front of the residential lots to
avoid obtaining backyard rights-of-way which would be very difficult. This would actually require,
possibly, more rights-of-way than the alley construction, but would generally be in less congested (but
more visible) areas. Opinions of probable costs were developed for the undergrounding construction as
well as obtaining rights-of-way.
Table 6-1 is as included in the Section 6 - Conclusion. It summarizes the various combinations of
alternatives ranging form rebuilding the existing 138-kV transmission line to placing all utilities
(transmission, distribution, cable TV, and telephone) underground.
City of University Park, Texas 2 - 1 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
SECTION 3
OVERHEAD TRANSMISSION ALTERNATIVES
OVERHEAD TRANSMISSION ALTERNATIVES
TXU Delivery (TXU) owns a 138-kV transmission line which passes through University Park, Texas.
The line interconnects the TXU Greenville Substation located southeast of University Park with the Loma
Alto Substation located southwest of University Park. The majority of the line passes through University
Park alleys. The line is constructed on wood poles. In addition to the transmission circuit, the poles also
carry a three-phase distribution primary circuit, single-phase secondaries, and telephone and CATV
circuits. Span lengths average 138 feet.
TXU intended to upgrade the line in such a manner that would result in taller poles, as discussed below.
However, the public has expressed that taller poles are not acceptable and has expressed a desire that the
transmission line be placed underground. Further, a University Park master plan from 1989 set out a
program of City-wide alley improvements that would place all overhead utilities underground. While the
City has undertaken alley improvements under a “mile-a-year” program, those improvements have been
limited to replacing underground pipes (water, sewer, and gas) and paving, but not overhead utilities. It is
not clear if the master plan intended for the transmission line to be placed underground. Underground
transmission is rarely constructed because of the high costs, whereas distribution lines and
communication lines are routinely undergrounded.
The transmission line was constructed in 1969. While TXU has replaced deteriorated poles from time to
time over the years, the poles, taken as a whole, are in poor condition today. Many are bowed and lean
precariously (Figure 3-1). The poles are frequently struck by passing vehicles, especially large trucks. In
fact, steel plates have been installed on many poles to protect them from vehicle strikes.
City of University Park, Texas 3 - 1 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Figure 3-1 - Existing Transmission and Distribution Line
TXU originally proposed to upgrade the existing Greenville - Lomo Alto 138-kV transmission line by
replacing every other pole with a new steel transmission pole. The intermediate poles would be cut off
above the distribution circuit. (Presumably, any defective intermediate poles would also be replaced.)
Because of public objection to the proposed heights of the poles, TXU then proposed to replace every pole
with a transmission pole, thereby reducing the pole heights by about 5 feet. Figure 3-2, prepared by TXU, is
a visual comparison of the existing line with a simulation of the line with all poles replaced.
Figure 3-2 - TXU Comparison of Existing and Proposed Transmission and Distribution Lines
City of University Park, Texas 3 - 2 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
With TXU’s proposed construction, there are two reasons why the replacement poles must be taller than the
existing structures:
1. The existing line was constructed with no overhead ground wire (OHGW) to protect
(shield) it from lightning strikes. We are not sure why the line was not shielded, as
virtually all transmission lines built in 1969 and since are shielded. In any case, the line is
susceptible to lightning outages. TXU has added lightning arresters at several locations to
the line. Even with the arresters, TXU reports that the line experienced three lightning
outages during 2005. (A common design criteria for transmission lines is that a line
should not experience more than one outage per year per 100 miles of line. For the
Greenville - Lomo Alto line, which is about 3.5 miles in length, under this criteria, the
line would not be expected to experience a lightning-caused outage more than once every
28 years on average.)
To add an OHGW to a transmission line, additional pole top is needed above the
conductors. In this case, 12-1/2 feet of additional pole is needed if the OHGW were
attached to the pole. As an alternative, the additional pole top can be reduced if the
OHGW is supported by a steel arm mounted at the top of the pole. With the steel arm,
the additional pole needed above the conductors is reduced to 6 feet.
2. The existing line was configured with the three transmission wires in a “starburst”
configuration. Two wires are supported by post insulators mounted to the top of the pole
in a horizontal orientation both left and right of the pole. The third wire is supported by a
post insulator mounted to the top of the pole in a vertical orientation. There is no way to
accommodate the vertical post when upgrading with an OHGW. Whereas the vertical
spacing between the top and bottom transmission wires was about 6 feet with the original
design, the spacing between the top and bottom wires must increase to 14 feet with the
new design.
ALTERNATIVE OVERHEAD ROUTES
Sega investigated alternate routes to the existing Greenville - Lomo Alto transmission line.
Any alternate route in University Park would have to go down east-to-west city streets or alleys.
We see no advantage to placing the line on an alternate University Park street or alley.
The purpose of the Greenville - Lomo Alto transmission line is to provide a second feed to the
Lomo Alto substation. If a second feed could be provided to Lomo Alto from another source,
the Greenville - Lomo Alto line could possibly be eliminated. Such a source was identified as
the North Haven Substation, located approximately three miles north of Lomo Alto near the
Dallas Tollway. Sega investigated the possibility of the Lomo Alto - North Haven transmission
City of University Park, Texas 3 - 3 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
line. While it appears that the line could be placed on public (tollway) right-of-way part of the
way, it is evident that a significant part of the line would require easements along private
residential properties. It is believed to place a transmission line on one set of residences, so as to
eliminate an existing transmission line from a second set of residences, would not be politically
possible.
ALTERNATIVE OVERHEAD OPTIONS
Sega investigated various alternatives for the overhead transmission line. The first alternative is a
reconstruction of the line using the same configuration as now exists. (In order to improve lighting
performance, all insulators will be equipped with lightning arresters. The existing line has had arresters
added only at selected locations.) The remaining transmission alternatives add one or two overhead ground
wires for lightning protection. As a basis of comparison, the two TXU proposed configurations are being
evaluated (even though the public has expressed disapproval).
Selection of Pole Type
The line can be constructed with either steel or wood poles. From an engineering standpoint, either is
acceptable. The diameters of wood and steel poles are nearly the same for poles of equivalent size and
strength.
Wood poles come in various shades of brown, depending on the type of preservative treatment specified.
Steel poles are usually furnished with either galvanized coating (light gray) or weathering steel (dark
brown). Selection of the color or "look" of the pole is one of personal preference. Some prefer the brown
look, perhaps because they more resemble trees. Others prefer the look of galvanized poles because they
tend to blend into the sky. We make no recommendation as to type or color of the poles as this value
judgment is to be made by TXU and the City.
Wood poles have two disadvantages as compared to steel poles:
1. Wood poles deteriorate over time due to fungal and insect activity.
2. Wood poles can warp or decay over time, as has been the case with the existing line.
City of University Park, Texas 3 - 4 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
The wood poles are pressure treated when new to protect against fungal and insect decay, but that treatment
dissipates over time. Wood poles are, typically, inspected and given ground-line treatment on a regular
cycle (typically every 10 years) to extend the longevity of the pole, but interim replacements due to decay
are typical after several years.
Similarly, direct-embedded steel poles are given protection against ground-line corrosion by application of
corrosion sleeves and a polymeric coating (similar to that used for pipelines) at and below the ground line.
Steel poles are periodically inspected to assure that galvanic corrosion is not a problem, but, if so, sacrificial
anodes are installed to arrest the corrosion. Also, after many years, the zinc coating on galvanized poles can
become depleted, requiring painting of the poles. Properly maintained steel poles should not need interim
replacements.
The relative pricing between wood, galvanized, and weathering steel poles varies with the market. Right
now, the purchase cost of wood holds an advantage over equivalent steel poles. However, the installation
costs of wood poles are much heavier to handle than steel poles. Steel poles of the sizes used here are
furnished in two pieces, facilitating improved maneuverability in the narrow alleys. Also, right now,
weathering steel poles are less expensive than galvanized poles, as the price of zinc has skyrocketed in
recent months. The opinions of probable costs contained herein are based on galvanized steel poles, but our
opinion is that the selection of wood or weathering steel poles would not significantly alter the probable
costs, especially since market conditions are less likely to change between now and the time of construction.
Lightning Protection
A transmission line cannot be protected against lightning strikes. However, there are two methods used to
deal with the strikes that hit the line.
The most common method is to install one or more overhead ground wires (shield wires) at the top of the
structure to intercept the lightning stroke and carry the energy to the ground where it is dissipated. In this
way, the flow of current in the current-carrying conductors is not interrupted and dangerous electrical surges
do not stress electrical equipment at the substations.
Another way to deal with lightning is to install lightning arresters. This is most often done as a remedy to
existing lines that have experienced excessive lightning outages due to nonexistent or ineffective shielding.
The arrester does not prevent the lightning stroke from hitting the current-carrying conductors, but is
City of University Park, Texas 3 - 5 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
designed to absorb the bulk of the stroke energy and carry it to the ground for dissipation. This reduces the
surge voltage at the electrical equipment. There is one manufacturer of transmission line arresters.
According to the manufacturer's information, effective lightning protection is accomplished when arresters
are applied to all current-carrying conductors at every structure. The usual application is to install the
arresters in parallel with the insulators.
TXU has installed arresters to some, but not all, of the existing structures. As mentioned earlier, TXU has
experienced lightning-caused outages even after application of the arresters. The one alternative discussed
here, where an overhead ground wire is not used, is based on installing arresters at all insulators.
The Alternative Options
Alternative 1 is the existing configuration, but with the pole structures replaced with new materials. In
addition, lightning arrestors would be added to all insulators. With this alternative, most poles would
remain the same height as now exist. Figure 3-3 shows the current configuration. The pole is shown as 57
feet above ground. Most of the existing poles are 57 or 52-1/2 feet above ground with a few as short as 48
feet and a few as tall as 70 feet above ground.
Alternative 2 is the original TXU proposal where every other pole would be replaced with a new
transmission pole. The intermediate poles would be cut off above the distribution primary and the
transmission conductors would span over them. The advantage of this “skip span” construction is that fewer
poles would have to be replaced and longer spans are more economical for transmission line construction.
Figure 3-4 illustrates the pole configuration of Alternative 2. Figure 3-5 shows the configuration of the
intermediate distribution poles based on current TXU standards.
Alternative 3 is the same as Alternative 2, except every pole would be replaced with a new transmission
pole. The advantage of this alternative is that the poles would be about 5 feet shorter. The disadvantage is
increased cost. Also, some would consider the “picket fence” effect to be less attractive.
Alternative 4 is similar to Alternative 2, except the middle transmission insulator and conductor are
mounted on the opposite side of the pole from the top and bottom insulators. This is shown by Figure 3-6.
The advantage of this “delta” configuration is that the pole height is reduced by 7 feet. Disadvantages are
that the middle insulator and conductor overhang yards and would be more troublesome to maintain. Also,
a second OHGW and support arm must be added, increasing the cost.
City of University Park, Texas 3 - 6 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Alternative 5 is to remove all under-build circuits and place them underground as promulgated by the 1989
master plan. This would leave only the transmission circuit. Without the undercircuits, the poles can be
shorter. Figure 3-7 illustrates the pole configuration for Alternative 5.
Alternative 6 is to remove the transmission line, but leave the undercircuits. The transmission line would
be built underground as explained elsewhere. The poles would be cut off above the distribution primary
and the undercircuits would be left as is. Figure 3-5 illustrates the typical distribution pole without the
transmission circuit.
Alternative 7 is to remove all overhead circuits and the supporting structures. Those circuits will be
placed underground as explained elsewhere.
Figure 3-8 shows the various overhead options side-by-side. Table 3-1 is a summary of the alternative
overhead options. Tables 3-2 through 3-7 are estimates of probable costs of the various overhead
alternatives.
City of University Park, Texas 3 - 7 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Table 3-2
University Par
k
Overhead Transmission Line Cost Estimate
Alternative 1 - "Status Quo Configuration"
Upgrade 1-Circuit 138-kV Transmission Circuit
Install Arrestors at all Insulators
Transfer 3-Phase Distribution Primary Underbuild
Transfer 1-Phase Distribution Secondary
Transfer Telephone and CATV Underbuilds
Tubular Steel Transmission Poles
125-foot Transmission Spans
2.72 Mile Length
5/19/2006 0:00
Material
MaterialLabo+ LaborExtended
r
UnitUnitQuantityUnit PriceUnit PriceUnit PricePrice
Transmission Circuit
Remove Existing Transmission Poleea111$0$3,000$3,000$333,000
Tangent Steel Pole (65'-1)ea111$3,254$6,508$9,762$1,083,582
Deadend Steel Poleea4$26,278$26,278$52,556$210,224
Deadend Foundationsea4$50,000$50,000$200,000
Transfer 636 kcmil ACSR Rookft43110$0$5$5$215,550
138-kV Post Insulator Assemblyea445$700$535$1,235$549,575
138-kV Strain Insulator Assemblyea24$643$715$1,358$32,592
138-kV Arrestorsea469$600$200$800$375,200
138-kV Jumper Postsea12$462$535$997$11,964
Mounting Bolts and Nuts,1 Lotea1$5,500$0$5,500$5,500
Pole Groundingea55$50$350$400$22,000
$3,039,187
Distribution and Communication Circuits
Cut Tops for Intermediate Distribution Poles ea0$0$0$0$0
Primary Crossarms for New Polesea111$150$90$240$26,640
Neutral Attachments for New Polesea111$40$30$70$7,770
Secondary Attachments for New Polesea111$40$30$70$7,770
Telcommunication Attachments for New Polesea222$40$30$70$15,540
Transfer 3-Phase Primaryft43110$0$5$5$215,550
Transfer Neutralft14370$0$5$5$71,850
Transfer Secondaryft14370$0$5$5$71,850
Transfer Telephoneft14370$0$5$5$71,850
Transfer CATVft14370$0$5$5$71,850
$560,670
Total Transmission + Distribution$3,599,857
Contingency 25%$899,964
Total$4,499,821
Table 3-3
University Par
k
Overhead Transmission Line Cost Estimate
Alternative 2 - Vertical Configuration, Skip Span
Upgrade 1-Circuit 138-kV Transmission Circuit
Transfer 3-Phase Distribution Primary Underbuild
Transfer 1-Phase Distribution Secondary
Transfer Telephone and CATV Underbuilds
Tubular Steel Transmission Poles
250-foot Transmission Spans
Intermediate Wood Distribution Poles (Existing)
2.72 Mile Length
5/19/2006 0:00
Material
MaterialLabo+ LaborExtended
r
UnitUnitQuantityUnit PriceUnit PriceUnit PricePrice
Transmission Circuit
Remove Existing Transmission Poleea55$0$3,000$3,000$165,000
Tangent Steel Pole (80'-1)ea55$4,782$9,564$14,346$789,030
OHGW Davit Armea55$100$50$150$8,250
Deadend Steel Poleea4$26,278$26,278$52,556$210,224
Deadend Foundationsea4$50,000$50,000$200,000
Install 3/8-inch OHGWft14370$0.5 $3.0 $3.5 $50,295
Transfer 636 kcmil ACSR Rookft43110$0$5$5$215,550
OHGW Suspension Assyea55$75$180$255$14,025
OHGW Deadend Assyea8$204$830$1,034$8,272
138-kV Post Insulator Assemblyea445$700$535$1,235$549,575
138-kV Strain Insulator Assemblyea24$643$715$1,358$32,592
138-kV Jumper Postsea12$462$535$997$11,964
Mounting Bolts and Nuts,1 Lotea1$5,500$0$5,500$5,500
Pole Groundingea55$50$350$400$22,000
$2,282,277
Distribution and Communication Circuits
Cut Tops for Intermediate Distribution Poles ea56$0$500$500$28,000
Primary Crossarms for New Polesea55$150$90$240$13,200
Neutral Attachments for New Polesea55$40$30$70$3,850
Secondary Attachments for New Polesea55$40$30$70$3,850
Telcommunication Attachments for New Polesea110$40$30$70$7,700
Transfer 3-Phase Primaryft43110$0$5$5$215,550
Transfer Neutralft14370$0$5$5$71,850
Transfer Secondaryft14370$0$5$5$71,850
Transfer Telephoneft14370$0$5$5$71,850
Transfer CATVft14370$0$5$5$71,850
$559,550
Total Transmission + Distribution$2,841,827
Contingency 25%$710,457
Total$3,552,284
Table 3-4
University Par
k
Overhead Transmission Line Cost Estimate
Alternative 3 - Vertical Configuration, Span-for-Span
Upgrade 1-Circuit 138-kV Transmission Circuit
Transfer 3-Phase Distribution Primary Underbuild
Transfer 1-Phase Distribution Secondary
Transfer Telephone and CATV Underbuilds
Tubular Steel Transmission Poles
125-foot Transmission Spans
2.72 Mile Length
5/19/2006 0:00
Material
MaterialLabo+ LaborExtended
r
UnitUnitQuantityUnit PriceUnit PriceUnit PricePrice
Transmission Circuit
Remove Existing Transmission Poleea111$0$3,000$3,000$333,000
Tangent Steel Pole (75'-1)ea111$4,400$8,800$13,200$1,465,200
OHGW Davit Armea111$100$50$150$16,650
Deadend Steel Poleea4$26,278$26,278$52,556$210,224
Deadend Foundationsea4$50,000$50,000$200,000
Install 3/8-inch OHGWft14370$0.5 $3.0 $3.5 $50,295
Transfer 636 kcmil ACSR Rookft43110$0$5$5$215,550
OHGW Suspension Assyea55$75$180$255$14,025
OHGW Deadend Assyea8$204$830$1,034$8,272
138-kV Post Insulator Assemblyea445$700$535$1,235$549,575
138-kV Strain Insulator Assemblyea24$643$715$1,358$32,592
138-kV Jumper Postsea12$462$535$997$11,964
Mounting Bolts and Nuts,1 Lotea1$5,500$0$5,500$5,500
Pole Groundingea55$50$350$400$22,000
$3,134,847
Distribution and Communication Circuits
Cut Tops for Intermediate Distribution Poles ea0$0$0$0$0
Primary Crossarms for New Polesea111$150$90$240$26,640
Neutral Attachments for New Polesea111$40$30$70$7,770
Secondary Attachments for New Polesea111$40$30$70$7,770
Telcommunication Attachments for New Polesea222$40$30$70$15,540
Transfer 3-Phase Primaryft43110$0$5$5$215,550
Transfer Neutralft14370$0$5$5$71,850
Transfer Secondaryft14370$0$5$5$71,850
Transfer Telephoneft14370$0$5$5$71,850
Transfer CATVft14370$0$5$5$71,850
$560,670
Total Transmission + Distribution$3,695,517
Contingency 25%$923,879
Total$4,619,396
Table 3-5
University Par
k
Overhead Transmission Line Cost Estimate
Alternative 4 - Delta Configuration, Skip Span
Upgrade 1-Circuit 138-kV Transmission Circuit
Transfer 3-Phase Distribution Primary Underbuild
Transfer 1-Phase Distribution Secondary
Transfer Telephone and CATV Underbuilds
Tubular Steel Transmission Poles
250-foot Transmission Spans
Intermediate Wood Distribution Poles (Existing)
2.72 Mile Length
5/19/2006 0:00
Material
MaterialLabo+ LaborExtended
r
UnitUnitQuantityUnit PriceUnit PriceUnit PricePrice
Transmission Circuit
Remove Existing Transmission Poleea55$0$3,000$3,000$165,000
Tangent Steel Pole (75'-1)ea55$4,400$8,800$13,200$726,000
OHGW Davit Armea110$100$50$150$16,500
Deadend Steel Poleea4$26,278$26,278$52,556$210,224
Deadend Foundationsea4$50,000$50,000$200,000
Install 3/8-inch OHGWft28740$0.5 $3.0 $3.5 $100,590
Transfer 636 kcmil ACSR Rookft43110$0$5$5$215,550
OHGW Suspension Assyea110$75$180$255$28,050
OHGW Deadend Assyea16$204$830$1,034$16,544
138-kV Post Insulator Assemblyea445$700$535$1,235$549,575
138-kV Strain Insulator Assemblyea24$643$715$1,358$32,592
138-kV Jumper Postsea12$462$535$997$11,964
Mounting Bolts and Nuts,1 Lotea1$5,500$0$5,500$5,500
Pole Groundingea55$50$350$400$22,000
$2,300,089
Distribution and Communication Circuits
Cut Tops for Intermediate Distribution Poles ea56$0$500$500$28,000
Primary Crossarms for New Polesea55$150$90$240$13,200
Neutral Attachments for New Polesea55$40$30$70$3,850
Secondary Attachments for New Polesea55$40$30$70$3,850
Telcommunication Attachments for New Polesea110$40$30$70$7,700
Transfer 3-Phase Primaryft43110$0$5$5$215,550
Transfer Neutralft14370$0$5$5$71,850
Transfer Secondaryft14370$0$5$5$71,850
Transfer Telephoneft14370$0$5$5$71,850
Transfer CATVft14370$0$5$5$71,850
$559,550
Total Transmission + Distribution$2,859,639
Contingency 25%$714,910
Total$3,574,549
Table 3-6
University Par
k
Overhead Transmission Line Cost Estimate
Alternative 5 - Vertical Configuration, Under Circuits Removed
Upgrade 1-Circuit 138-kV Transmission Circuit
Distribution and Communication Circuits Removed
250-foot Transmission Spans
2.72 Mile Length
5/19/2006 0:00
Material
MaterialLabo+ LaborExtended
r
UnitUnitQuantityUnit PriceUnit PriceUnit PricePrice
Transmission Circuit
Remove Existing Transmission Poleea111$0$3,000$3,000$333,000
Tangent Steel Pole (60-2)ea55$2,608$2,608$5,216$286,880
OHGW Davit Armea55$100$50$150$8,250
Deadend Steel Poleea4$26,278$26,278$52,556$210,224
Deadend Foundationsea4$50,000$50,000$200,000
Install 3/8-inch OHGWft14370$0.5 $3.0 $3.5 $50,295
Transfer 636 kcmil ACSR Rookft43110$0$5$5$215,550
OHGW Suspension Assyea55$75$180$255$14,025
OHGW Deadend Assyea8$204$830$1,034$8,272
138-kV Post Insulator Assemblyea445$700$535$1,235$549,575
138-kV Strain Insulator Assemblyea24$643$715$1,358$32,592
138-kV Jumper Postsea12$462$535$997$11,964
Mounting Bolts and Nuts,1 Lotea1$5,500$0$5,500$5,500
Pole Groundingea55$50$350$400$22,000
$1,948,127
Distribution and Communication Circuits
Remove 3-Phase Primaryft43110$0$5$5$215,550
Remove Neutralft14370$0$5$5$71,850
Remove Secondaryft14370$0$5$5$71,850
Remove Telephoneft14370$0$5$5$71,850
Remove CATVft14370$0$5$5$71,850
$502,950
Total Transmission + Distribution$2,451,077
Contingency 25%$612,769
Total$3,063,846
Table 3-7
University Par
k
Overhead Transmission Line Cost Estimate
Alternative 6 - Remove Transmission, Leave Under Circuits
Remove 1-Circuit 138-kV Transmission Circuit
Distribution and Communication Circuits Untouched
125-foot Spans
2.72 Mile Length
5/19/2006 0:00
Material
MaterialLabo+ LaborExtended
r
UnitUnitQuantityUnit PriceUnit PriceUnit PricePrice
Transmission Circuit
Cut Top off Existing Transmission Poleea111$0$500$500$55,500
Remove 636 kcmil ACSR Rookft43110$0$5$5$215,550
$215,550
Contingency 25%$53,888
Total$269,438
Table 3-8
University Par
k
Overhead Transmission Line Cost Estimate
Alternative 7 - Remove Overhead Lines in Entiret
y
Upgrade 1-Circuit 138-kV Transmission Circuit
Distribution and Communication Circuits Removed
250-foot Transmission Spans
2.72 Mile Length
5/19/2006 0:00
Material
MaterialLabo+ LaborExtended
r
UnitUnitQuantityUnit PriceUnit PriceUnit PricePrice
Transmission Circuit
Remove Existing Transmission Poleea111$0$1,000$1,000$111,000
Remove 636 kcmil ACSR Rookft43110$0$5$5$215,550
$326,550
Distribution and Communication Circuits
Remove 3-Phase Primaryft43110$0$5$5$215,550
Remove Neutralft14370$0$5$5$71,850
Remove Secondaryft14370$0$5$5$71,850
Remove Telephoneft14370$0$5$5$71,850
Remove CATVft14370$0$5$5$71,850
$502,950
Total Transmission + Distribution$829,500
Contingency 25%$207,375
Total$1,036,875
SECTION 4
UNDERGROUND TRANSMISSION ROUTES
UNDERGROUND TRANSMISSION ROUTES
INTRODUCTION
TXU Electric Delivery (TXU) is proposing to rebuild the 138-kV transmission line between its Greenville
and Lomo Alto Substations using steel pole structures. As a result of concerns of some of the citizens of
the City of University Park, Texas, Sega Inc. and its subcontractor, Power Delivery Consultants, Inc.
(PDC), were commissioned to prepare underground transmission alternatives to the TXU proposed
overhead line. This document describes preliminary designs and cost estimates for two underground
transmission alternatives.
PDC is an engineering services company that specializes in the design and specification of underground
transmission lines. PDC has prepared cost estimates, completed preliminary designs, and provided
specifications for six underground transmission lines in the State of Texas. These include the 8.5-mile,
138-kV XLPE underground transmission line between Port Isabel and South Padre Island and the
relocation of 6 miles of two, 138-kV overhead transmission lines for widening of the Katy Freeway in
Houston.
TRANSMISSION LINE ALIGNMENTS
The existing TXU Greenville - Lomo Alto 138-kV underground transmission line in the City of University
Park is constructed on wood poles that are primarily located in alleys between residential streets. The
existing wood poles support a 138-kV transmission line as well as a distribution line, pole-mounted
distribution transformers, and some residential service cables.
Early during the Study effort, Sega was informed that the City of Highland Park was considering
replacing an underground water line that resides beneath Mockingbird Lane. This would require major
excavation and disruption of traffic during construction. It was felt that, while such disruption was
underway, it might be an opportunity to install underground cables coincident with the water line project.
However, we understand that Highland Park has now decided not to excavate, but rather repair the water
line in situ. There would, therefore, be no advantage to locating the underground line along Mockingbird
as compared to any other east-to-west street in University Park.
City of University Park, Texas 4 - 1 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
PDC considered the following two alternatives for constructing an underground transmission line to replace
the existing 138-kV overhead transmission line. This document does not address the future disposition of
the distribution lines on the wood poles.
Existing Right-Of-Way
The first underground alternative (UG1) that was investigated was to construct a 138-kV underground
transmission line along the alignment for the existing 138-kV overhead transmission line. However, there
are numerous challenges to construct a conventional open-trench underground transmission line down the
narrow alley where the existing line is located. The following issues make this underground alternative
difficult and expensive to construct.
There are numerous underground utilities (i.e., sewer, gas, and water) in the alleys that would have to be
relocated to excavate the transmission cable trench or the widths of the alleys would have to be increased to
facilitate excavation of the cable trench.
The widths of the existing alleys are too narrow to accommodate a conventional, open-cut cable trench. This
being the case, the width of the alleys would have to be increased to the size of the existing utilities. More
specifically, the increased right-of-way width would have to be on the side of the alley that is opposite from
the existing wooden poles. Widening the alleys would require acquisition of property from local residents
and existing structures would have to be relocated or modified in some cases. The seven or eight splice
vaults for the underground transmission cables (typically 8-feet wide by 20-feet long by 7-feet high) would
have to be located in the side streets for the majority of the existing alignment.
Because of the above construction issues, the only technically feasible method of constructing the
underground transmission line along the existing alignment would be to use a trenchless construction
method called horizontal directional drilling (HDD). In this case, HDD rigs would bore beneath the existing
utilities (20 to 30 feet below the surface) with splice vaults installed on side streets. Additional details of the
HDD equipment and limitations are presented in a following section.
Closest City Streets
The second and preferred alternative (UG2) for constructing the underground transmission line is to
construct the line in the closest City streets to the existing overhead transmission line. In this case,
conventional open-cut excavation equipment (e.g., backhoes and/or trackhoes) would be used to excavate a
City of University Park, Texas 4 - 2 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
trench along one of the closest City streets to the existing alignment and a concrete-encased duct bank would
be installed to accommodate subsequent installation of the transmission cables. The seven or eight concrete
vaults would be installed in the City streets for splicing of the transmission cables.
UNDERGROUND TRANSMISSION TECHNOLOGIES
Several cable system types could be used for the 138-kV underground transmission line: High-pressure,
fluid-filled (HPFF); high-pressure, gas-filled (HPGF); extruded-dielectric (ED); and self-contained, fluid-
filled (SCFF). These systems are described in the following sections.
Extruded-Dielectric Cable, XLPE, and EPR
ED cables have an extruded insulation that requires no pressurization. They can, therefore, be installed
individually in plastic ducts, similar to distribution cables. ED cables with cross-linked polyethylene
(XLPE) insulation are subject to “water trees” just as distribution cables are; therefore, the transmission
cables always have a metallic moisture barrier. Lead is traditionally used and is considered the best
material, but aluminum and copper moisture barriers and laminates of these materials are becoming
common. Ethylene Propylene Rubber (EPR) insulation is installed without a moisture barrier because of its
better resistance to damage from moisture. Ducts are typically PVC provided in 10-foot or 20-foot lengths,
held in place with spacers and encased in concrete, but the duct size for a 138-kV cable is nominal 6 inches
(6.625-inches OD) versus the nominal 5-inch ducts used for distribution cables. Transmission cables
typically require thicker, Schedule 40 ducts. Figure 1 shows a 138-kV XLPE cable.
Figure 4-1 - ED (XLPE) Insulated Cable
City of University Park, Texas 4 - 3 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
High-Pressure, Fluid-Filled Cable
Each cable consists of a conductor, typically copper, and has approximately 0.44 inches of insulation
consisting of helically-applied paper tapes that are factory impregnated with a very high-viscosity, dielectric
liquid. The three cables for the three-phase system are approximately 3- to 3.5-inches in diameter and are
installed in a coated and cathodically protected 8-5/8-inch OD, 0.25-inch wall mild steel pipe. The pipe is
provided in double-random lengths 45- to 55-feet long. Pipe ends are flared at the coating facility and
backing rings are inserted to align the pipe ends in the field to provide a smooth inner profile and prevent
weld slag from entering the pipe during welding. The welds are x-rayed and tested with a holiday detector
after coating is applied in the weld area. After the three cables are pulled simultaneously into the pipe and
spliced and terminations are installed, the pipe is evacuated and pressurized with a dielectric fluid
(alkylbenzene or polybutene) to a nominal 200-psig pressure to maintain the electrical strength of the
insulation. Figure 4-2 shows a pipe-type cable.
Figure 4-2 - Typical Pipe-Type Cable
High-Pressure, Gas-Filled Cable
High-pressure, gas-filled (HPGF) cables have the same general construction as the HPFF pipe-type cable,
except that the pipe is filled with dry nitrogen gas pressurized at 200 psig. The insulation thickness is
slightly thicker (0.5 inch) for this type of cable system.
Self-Contained, Fluid-Filled (SCFF) Cable
The cables have copper conductors with hollow cores through which dielectric liquid is passed to pressurize
the wrapped paper insulation. The cables are installed individually in plastic ducts. This type is seldom
used on land cables (it is very common on submarine cables) and was not evaluated for this Study.
City of University Park, Texas 4 - 4 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Figure 4-3 - Typical SCFF Cable
Advantages and Disadvantages of Each Cable Type
Advantages Disadvantages
Insulation thickness slightly greater and
HPFF Proven, reliable system; in service at 138-kV
••
70 years ampacity slightly lower than SCFF system
Steel pipe provides good mechanical
•
protection Specialized equipment needed for installation
•
Lower magnetic fields than other cable types and repair
•
Can be installed somewhat more quickly Electrical losses and charging currents higher
••
than ED cables than for ED cables
Ratio of normal-to-emergency ampacity Restoration time is longer than ED
••
typically higher than for XLPE or EPR cables
U.S. supplier and several U.S. installers
•
ED No dielectric fluid or fluid pressurizing Splices and terminations have been a problem
••
equipment is required in some cases
Less complex cable system Less forgiving of defects in manufacturing/
••
Lower dielectric losses and VARS than installation
•
HPFF cable Necessary to have splices and terminations
•
No special precautions for circuit restoration supplied by the cable supplier and preferably
•
Installation can use same equipment as installed by cable factory technicians.
•
distribution cables Complex sheath bonding methods; sheath
•
More than a dozen suppliers world-wide voltages can be a problem
•
(and a U.S. supplier)
SCFF
Proven, reliable system, in service at 138-kV Most complex of the cable systems
••
•
for 70 years Highest maintenance
No domestic suppliers
•
City of University Park, Texas 4 - 5 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
University Park Application
The project team selected the ED cable (XLPE insulation) system to be the best transmission cable
technology for the City of University Park underground transmission line alternative. We believe that an
XLPE transmission cable system is best suited for this application for the following reasons:
1. It currently is the most common type of 138-kV transmission cable system being installed
in the U.S. and most other places in the world.
2. Minimal space is required for overhead-to-underground transitions. One of the most
common ways of making overhead to underground transitions for XLPE cable systems are
pole-mounted terminations as shown in Figure 4-4. Overhead-to-underground transitions
for HPFF cable installations are generally constructed by ground-level, fenced-in areas
similar to a small substation. Usually, at least one of the two ends is terminated in a
substation because a fluid pressurization unit is required.
3. Minimal maintenance is required for this type of cable system.
Figure 4-4 - Typical Overhead-to-Underground Transition for 138-kV XLPE Cable System
TXU has both HPFF and XLPE transmission cables at different locations on its transmission system and
indicated that it would consider either type (HPFF or XLPE) of transmission cable as underground
alternatives for the Greenville - Lomo Alto line.
City of University Park, Texas 4 - 6 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
DESIGN REQUIREMENTS
A preliminary underground transmission cable system design was completed prior to preparing cost
estimates for the two underground system alternatives. The technical design requirements that were
assumed for the underground transmission alternatives were:
1. Transmission Capacity: The electric-power transmission capacity of the underground
transmission line must be equal to the power transmission capacity of the overhead
transmission line alternatives. The largest conductor size that can be supported by steel
pole replacements for the wood poles would be 795 kcmil ACSR. The current-carrying
rating of this type of conductor and typical span lengths would be approximately
1,000 amperes. For underground transmission systems, the 24-hour load factor (a
measure of daily load variability) is an important design parameter. PDC assumed a 24-
hour load factor of 75 percent based on typical underground transmission line design
criteria provided by TXU (Lemmon Avenue Substation Underground Transmission
Project).
2. 138-kV XLPE Transmission Cables: The XLPE transmission cable technical
specifications provided by TXU were used for the preliminary design. TXU’s
specifications for 138-kV transmission cables is a lead-sheath cable with 0.850-inch thick
XLPE insulation that comply with U.S. industry specifications for this type of cable
(AEIC CS7-93 - Specifications for Cross-Linked, Polyethylene, Insulated, Shielded Power
Cables Rated 69 through 138 kV). AEIC CS7-93 specifies a maximum conductor
temperature of 90 degrees C for normal operating conditions.
3. Cable System Grounding: XLPE transmission cable system sheaths are typically
grounded using special methods to minimize induced sheath currents. These special
bonding methods to reduce induced sheath currents result in induced sheath voltages.
TXU’s specifications require that the induced sheath voltages do not exceed 150 volts
during normal operating conditions. This requirement is one constraint that determines
the maximum distance between cable manholes (splice vaults).
4. Cable Pulling Tensions and Sidewall Bearing Pressure: Other design constraints are the
maximum pulling tension that can be applied to the cables during installation and the
maximum pressure applied to the cable as it is pulled around bends in the duct bank.
These constraints also limit the maximum distance between splice vaults. AEIC G1
recommendations for maximum pulling tension and sidewall bearing pressure were taken
into account when performing preliminary design calculations for the underground
transmission alternatives.
CONSTRUCTION METHODS
Construction methods assumed for the two underground alternatives are described in the following sections.
City of University Park, Texas 4 - 7 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Horizontal Directional Drilling (UG1
)
As discussed in Section 2, HDD is the only feasible method for installing underground transmission cables
along the alignment for the existing 138-kV transmission line. This is due to the narrow alleys and existing
underground utilities. Figure 4-5 shows a typical cross section of a 138-kV XLPE transmission line using
HDD boring. The 28-inch diameter bore would be constructed at a depth of 25 to 35 feet below the surface
of the ground, depending on the mechanical properties of the soil along the transmission line alignment.
The next step in the HDD process is to drill a pilot hole and then back-ream the pilot bore to expand the
bore diameter to 28 inches (Figure 4-5). Set-up areas for the drilling rigs must be large enough to
accommodate the equipment for containing and processing the drilling mud (water/bentonite slurry).
The next step in the construction process (Figure 4-6) is to assemble strings of the HDPE pipes that are long
enough to be pulled into the entire length of the bore and pull them into the bore.
City of University Park, Texas 4 - 8 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Transmission Cable
28-inch ö HDD Bore
Drilling Mud and Soil
6-inch SDR 11 HDPE Pipe
Figure 4-5 - HDD Bore Cross Section
Figure 4-6 - HDPE Pipe Strings
HDD rigs (Figure 4-7) are available that can be used to construct bores several feet in diameter for bore
lengths over one mile; however, they require a large amount of area (i.e., 100 by 150 feet) to accommodate
auxiliary equipment, such as drilling mud processing and storage equipment, cranes, and stockpiles of drill
pipe. Another limitation for XLPE underground transmission cables is the maximum cable pulling length of
approximately 3,000 feet.
City of University Park, Texas 4 - 9 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Figure 4-7 - Large HDD Boring Rig Used for 3,500-Foot Bore
The set-up area for midi-size HDD rigs (Figure 4-8) and auxiliary equipment could be accommodated on
side streets for the City of University Park underground Alternative 1, but the maximum bore length for a
28-inch diameter bore is approximately 1,200 to 1,300 feet, depending on soil conditions.
Figure 4-8 - Midi-Size HDD Boring Rig Used for 1,200-Foot Bore
City of University Park, Texas 4 - 10 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Concrete-Encased Duct Bank Construction (UG2)
XLPE transmission cable underground transmission lines are typically constructed in urban and suburban
environments using concrete-encased duct banks (see Figure 4-9).
Figure 4-9 - Typical XLPE Transmission Cable Duct Bank Installation
Concrete-encased duct banks are typically used in City streets because the length of open trench at any
one time during construction can be limited to 300 or 400 feet. The transmission cables are then installed
after the duct bank construction and splice vault installation have been completed. Concrete-encased
duct banks also provide good mechanical protection against dig-ins after they have been placed in
service.
Figure 4-10 shows a trench cross section for the street construction alternative (UG2).
City of University Park, Texas 4 - 11 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Figure 4-10 - Trench Cross Section for Street Construction (UG2)
City of University Park, Texas 4 - 12 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Transmission Cable Splice Vaults
City of University Park Power Delivery Consultants, Inc.
The transmission cable splices for both alternatives would be installed in pre-fabricated concrete vaults
approximately 20-feet long, 7-feet wide, and 7-feet high (see Figures 4-11 and 4-12).
Figure 4-11 - Concrete Splice Vault
7'
7'
Figure 5-5. Trench cross section for street construction (UG2)
Figure 4-12-Pre-fabricated Concrete Splice vaults
City of University Park, Texas 4 - 13 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
CABLE INSTALLATION
The cables are shipped to the construction site on large reels that are approximately 12-feet high by 8-feet
wide and pulled into the cable ducts or HDPE pipes one at a time (Figure 4-13) with a cable winch (Figure
4-14) at the opposite end of the cable duct.
Figure 4-13 - Cable Pulling Into Concrete-Encased Duct Bank
Figure 4-14 - Cable Pulling Wench
City of University Park, Texas 4 - 14 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
The cable splicing activities (Figure 4-15) at each of the manholes takes approximately one week.
Figure 4-15 - Cable Splicing in Concrete Vault
UNDERGROUND ALIGNMENTS
The alignments for the two underground transmission alternatives roughly follow the path of the existing
overhead transmission line from the eastern City limit at the North Central Expressway to the western City
limit at the North Tollway where the existing line turns south to the Lomo Alto substation. It was assumed
that overhead-to-underground transitions (riser poles) would be installed at both of these locations.
Additional details of the two underground alternatives that were selected by the Sega/PDC team are given in
the following sections.
Existing Right-of-Way
The eastern overhead-to-underground transitions would occur at a small park located at the intersection of
Willard and Daniel (Figure 4-16).
City of University Park, Texas 4 - 15 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Figure 4-16 - Proposed Location for Eastern Overhead-to-Underground Transition
City of University Park, Texas 4 - 16 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Splice Vault
Stanford
Amherst
Figure 4-17 - Alignment for Underground Alternative 1 (UG1)
The alignment for this option would proceed from east to west as follows:
1. The first section of the alignment would be concrete-encased duct bank from the riser pole to the
eastern end of the alley between Daniel and Rosedale (approximately 200 feet).
2. The transmission cables would then be installed beneath the alley (between Daniel and Rosedale)
using HDD with the bore machine set up in the small park shown in Figure 4-17. The opposite
end of the HDD bore and first manhole would be located in the street at Boedeker. This is a
distance of approximately 1,100 feet.
3. The underground transmission line would then turn 90 degrees to the north and proceed to the
alley between Amherst and Stanford. It would be installed beneath the surface of Boedeker Street
in a concrete-encased duct bank using conventional open-cut excavation, except where it crosses
Lovers Lane. A construction method called pipe jacking and boring would be used to install a
steel casing or reinforced concrete pipe (RCP) beneath Lovers Lane to avoid disruption of the
traffic of this relatively busy street.
4. The alignment would turn 90 degrees to the west at the alley between Amherst and Stanford. The
underground transmission line would then follow the existing transmission line route from
Boedeker to Lomo Alto where it would return to overhead construction via a second riser pole.
The underground transmission cables would be installed beneath the alley located between
Amherst and Stanford using HDD. This distance of approximately 2.1 miles would be traversed
by means of 10 bores shown in Table 3-1 with six manholes located on the side streets.
City of University Park, Texas 4 - 17 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Number End 1 End 2 Distance (ft)
1 Boedeker Durham 945
2 Durham Airline 775
3 Airline Hillcrest 1,185
4 Hillcrest Dickens 915
5 Dickens Thackery 730
6 Thackery Baltimore 1,130
7 Baltimore Tulane 1,130
8 Tulane Preston 1,130
9 Preston Douglas 1,290
10 Douglas Lomo Alto 1,230
Table 4-1 - HDD Bores between Boedeker and Lomo Alto
City of University Park, Texas 4 - 18 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
The number of HDD bores could be significantly reduced if there were space to set up the full-size HDD
boring machines. However, the side streets along the alignment are only wide enough to accommodate the
midi-size HDD rigs shown in Figure 4-7 and the maximum distance for this type of rig is approximately
1,200 to 1,300 feet.
There would be a total of seven splice vaults for the above underground alignment. Several of the shorter
bores would be connected without splice vaults.
Closest City Streets
The second underground alternative (UG2) would start at the same overhead-to-underground transition
location as the first underground alternative (see Figure 4-17 and Figure 4-18).
Splice Vault
Stanford
Amherst
Lovers Lane
Rosedale
Daniel
Figure 4-18 - Alignment for Underground Alternative 1 (UG2)
City of University Park, Texas 4 - 19 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
The underground transmission line would then be constructed in City streets as follows:
1. The cables would be installed in concrete-encased duct bank from the riser pole
in the small park to Rosedale where it would turn west.
2. The concrete-encased duct bank would then proceed west along Rosedale to
Boedeker where it would turn north on Boedeker.
3. The cable duct bank would then follow Boedeker to Stanford where it would
turn 90 degrees to the west. As in the previous underground alternative, pipe
jacking and boring would be used to install the cables in a steel casing beneath
Lovers Lane.
4. The cable duct bank would then follow Stanford to Lomo Alto where a
transition would be made from underground construction to overhead
construction at a second riser pole.
The cable duct bank would be installed with a minimum cover of 36 inches for the majority of the
alignment. There are six locations where the duct bank will have to dip beneath existing storm and
sanitary sewers. The deepest of these is between Tulane and Baltimore where a 15-inch sanitary
sewer is installed below a large box culvert storm sewer. The cable duct bank would have to dip
below both of these facilities with a depth to the top of the duct bank of 14 feet.
The underground alignment for this alternative between Boedeker and Lomo Alto could be
constructed along Amherst rather than Stanford. There would be eight manholes for the above
underground transmission alignment.
The second UG (i.e., closest City streets) is the favored alternative because:
1. There are very few underground utilities located in Stanford and Amherst.
2. It is less expensive to construct concrete-encased duct bank compared to the
HDD.
3. There are fewer construction uncertainties with conventional open-cut
construction compared to HDD construction.
City of University Park, Texas 4 - 20 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
CABLE SIZING
Ampacity calculations were performed to determine the cable conductor sizes that will be
necessary to achieve an ampacity rating of 1,000 amperes for the two underground transmission
alternatives. The design parameters shown in Table 4-2 were used to perform the ampacity
calculations.
Parameter Value Units
24-Hour Load Factor 75 Percent
Native Soil Thermal Resistivity 70 °C - cm/W
Maximum Soil Ambient Temperature at 6-Foot Depth 25 °C
Maximum Soil Ambient Temperature at 30-Foot Depth 22 °C
Concrete-Encasement Thermal Resistivity 60 °C - cm/W
HDD Grout Thermal Resistivity 80 °C - cm/W
Maximum Conductor Temperature, Normal Operation 90 °C
Maximum Conductor Temperature, Emergency Operation 105 °C
Burial Depth (Top of Duct Bank) 3 to 9 ft
Burial Depth (Top of HDD Bore) 25 to 35 ft
Cross-Bonding
Cable Sheath Bonding --
and Single-Point
Table 4-2 - Ampacity Calculation Parameters
Results of the ampacity calculations are shown in Table 4-3.
Copper
Depth Conductor Ampacity
Conductor Size
Construction
(ft)Stranding(A)
(kcmil)
Compressed
2x2 Duct Bank 4 1,750 1,118
Concentric
Compressed
2x2 Duct Bank 9 1,750 1,060
Concentric
Compact
2x2 Duct Bank 9 1,750 1,133
Segmental
Compressed
2x2 Duct Bank 14 1,750 1,038
Concentric
Compact
2x2 Duct Bank 14 1,750 1,104
Segmental
Compressed
HDD HDPE Pipe 30 1,750 987
Concentric
Compact
HDD HDPE Pipe 30 1,750 1,054
Segmental
Table 4-3 - Results of Ampacity Calculations
City of University Park, Texas 4 - 21 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
In summary, the ampacity calculations indicate that a 1,750 kcmil compressed round copper
conductor will meet the 1,000-ampere ampacity target at all locations for the concrete-encased
duct bank UG2 alternative.
A 1,750-kcmil compact segmental copper conductor will be required to meet the ampacity
requirement for the HDD (UG1) installation alternative. The segmental conductor increases the
cable rating by reducing skin effect losses.
OPINION OF PROBABLE COSTS
Probable costs were prepared for both underground cable system alternatives based on PDC’s
observations from several recent XLPE transmission cable projects. Details of the probable costs
are shown at the end of this Section.
The following assumptions were made in preparing probable costs for the 2.7-mile long
underground transmission line:
1. A single contract would be issued to engineer, procure, and construct (EPC) the
underground transmission line. It is common for utilities to award a single EPC
or turn-key contract to a transmission cable construction company or cable
company to take full responsibility for the design, supply of material, and
construction of the underground transmission line.
2 No right-of-way or easement costs are included. It is assumed that the
underground transmission line will be constructed on the existing right-of-way
for the overhead line or that the City of University Park will issue easements
where the underground lines are constructed in City streets. Any fees that are
required to extend the existing right-of-way agreements for underground
constructions should be added to the probable costs in this document.
3. Cable and accessory costs are based on current typical costs for this equipment
and PDC’s estimate of the costs during the next 12-month period. It should be
noted that the cost of transmission cable and, to a lesser extent, transmission
cable accessories fluctuate significantly, depending on the cost of metals, other
market conditions, and foreign currency exchange rates.
4. No TXU engineering costs are included. TXU or TXU’s subcontractor would
be responsible for reviewing the EPC contractor’s detailed design calculations,
construction drawings, as-built drawings, and other project documentation.
5. No TXU field construction inspection costs are included. TXU or TXU’s
subcontractor should perform construction inspection to insure that the
underground transmission line is constructed in compliance with the project
specifications.
City of University Park, Texas 4 - 22 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
6. The costs do not include the costs to solicit and evaluate EPC proposals for the
lines.
7. The costs do not include the cost of performance or warranty bonds.
8. The costs do not include the cost of decommissioning of the existing overhead
line.
Costs for construction of the underground transmission line include the following:
1. Materials required to construct the underground transmission line including
vaults, riser poles, and 138-kV surge arresters for each of the cable
terminations.
2. Civil construction costs required to excavate and backfill trenches and pits for
the manholes or splice pits.
3. Material and equipment for installing steel casings and PVC conduits at major
road crossings.
4. Equipment and labor for pulling the transmission cables.
5. Equipment and personnel for splicing and termination of the transmission
cables.
6. Field construction supervision for cable installation and civil construction work.
7. Performing field and laboratory soil thermal resistivity survey.
8. Cost of performing post-construction commissioning tests.
9. As-built plan and profile drawings of the underground lines.
10. Local sales and federal import taxes.
11. Shipping charges for material to the construction site.
Table 4-4 contains a summary of the opinion of probable costs.
Component Existing Right-of-Way City Streets
Material $4,487,000 $3,937,000
Civil Works $9,616,000 $6,077,000
Engineering $603,000 $432,000
Project Management, Inspection $648,000 $648,000
Miscellaneous (Taxes, etc.) $1,053,000 $771,000
Totals $16,424,000 $11,865,000
Table 4-4 - Summary of Underground Transmission Opinion of Probable Costs
City of University Park, Texas 4 - 23 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
OPINION OF PROBABLE COSTS FOR GREENVILLE - LOMO ALTO138 KV XLPE UG1 ALTERNATIVE 138 kV XLPE
Cable Circuits With 1750 kcmil Segmental Copper Conductor XLPE Cables
Date
5/7/06 MVA Rating 239
Route Length (ft) 14,260 Circuits
1
TrenchLength (ft) 14,260 Cables Per Phase
1
Cables Per Trench 3 Manholes/Ckt.
7
Nominal Cable Length (ft) 42,780 3-Ph Terminations
2
Unit
Unit
Item Description Qnty. Material Material Qnty.
Labor Labor Total
1 ROW Prep./Service Roads - 14,260 8 114,080 114,080
2 Trench Excavation, Streets (ft) 1,854 001,854 120 222,456 222,456
3 Trench Excavation, Unpaved (ft) 200 200 50 9,982 9,982
4 Spoil Disposal (cu.yd.) 2,377 10 23,767 23,767
5 Construct Duct Bank (tr.ft.) 14,260 24342,24014,260 32 456,320 798,560
6 Trench Shoring (tr.ft.) 14,260 14,260 30 427,800 427,800
775
Fluidized Thermal Backfill (cu.yd.) 2,377 178,2502,377 10 23,767 202,017
8 Paving Repair (sq.ft.) 3,708 1037,0763,708 8 29,661 66,737
9 Horizontal Directional Drilling (ft) 12,207 38463,84912,207 400 4,882,624 5,346,473
10 Pipe Jacking and Boring (ft) 250 4812,000250 625 156,250 168,250
11 Trench Steel Plating (tr.ft.) 1,854 001,854 10 18,538 18,538
12 Splice Vault (ea.) 7 42,000294,0007 20,000 140,000 434,000
13 138 kV XLPE 1750 kcmil cable (ft.) 43,819 451,971,8641,971,864
14 Ground continuity conductor (ft) 14,260 2.535,6508 2,000 16,000 51,650
15 Duct Mandrel Testing 25 4,000 100,000 100,000
16 Cable Installation (section pulls) 24 8,000 192,000 192,000
17 Ground conductor installation (sections) 8 2,000 16,000 16,000
18 138 kV terminations (ea.) 6 8,00048,0006 8,000 48,000 96,000
19 Manufacturer's field supervisor (week) 12 7,000 84,000 84,000
20 Splice and termination special tools (lot) 1 25,00025,00025,000
21 138 kV, 1-phase splices (ea.) 21 9,000189,00021 9,000 189,000 378,000
55
22 Cross-Bonding Link Boxes 8,14037,9873,000 14,000 51,987
23 3-Ph Grounding Link Boxes 3 6,27020,9003 1,000 3,333 24,233
24 Cable Clamps 245 13031,850245 100 24,500 56,350
25 Upaved ROW restoration (sq.ft.) 399 1399399 1 399 799
26 Cable Termination Structures 2 52,000104,0002 6,000 12,000 116,000
27 Mob./Demobi. Cable Contractor (ea.) 2 30,000 60,000 60,000
28 Mobile Office/Storage Areas 75,000
29 Traffic Control lot 75,000 85,000
30 Security (man-days) 360 300 108,000 108,000
31 Test & Energization (ea) Lump Amt. 20,000 20,000 20,000
32 Emergency repair parts (lot) 1 109,500109,500 0 109,500
33 Subtotal $3,901,565$7,467,477 $11,454,042
34 Specification Preparation $35,000 $35,000
35 Detailed Engineering (ea.) $568,452 $568,452
36 Surveys (lot) $250,000 $250,000
37 Soil Survey $33,000 $33,000
38 Construction Supervision (days) 360 800 $288,000 $288,000
39 Project Management 300 1200 $360,000 $360,000
40 Field Construction Inspection 360 800 $288,000 $288,000
41 Construction Contingency & Profit (20%) $1,493,495 $1,493,495
42 Material Contingency & Profit (15%) $585,235 $585,235
43 Subtotals $4,486,800$10,783,424
7% $1,068,916
44
Sales Tax
$16,424,140
Total Cost
City of University Park, Texas 4 - 24 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
OPINION OF PROBABLE COSTS FOR GREENVILLE - LOMO ALTO138 KV XLPE UG2 ALTERNATIVE 138 kV XLPE Cable
Circuits With 1750 kcmil Copper Conductor XLPE Cables
Date
5/7/06 MVA Rating 239
Route Length (ft) 14,260 Circuits
1
TrenchLength (ft) 14,260 Cables Per Phase
1
Cables Per Trench 3 Manholes/Ckt.
7
Nominal Cable Length (ft) 42,780 3-Ph Terminations
2
Unit
Unit
Item Description Qnty. Material Material Qnty.
Labor Labor Total
1 ROW Preparation - 14,260 8 114,080 114,080
2 Trench Excavation, Streets (ft) 12,834 0012,834 120 1,540,080 1,540,080
3 Deep Trench Excavation (ft) 1,426 1,426 312 444,912 444,912
4 Spoil Disposal (cu.yd.) 2,377 12 28,520 28,520
5 Construct Duct Bank (tr.ft.) 14,260 24342,24014,260 32 456,320 798,560
6 Trench Shoring (tr.ft.) 14,260 14,260 30 427,800 427,800
775
Fluidized Thermal Backfill (cu.yd.) 2,377 178,2502,377 10 23,767 202,017
8 Paving Repair (sq.ft.) 30,897 8247,17330,897 3 92,690 339,863
9 Pipe Jacking and Boring (ft) 250 4812,000250 625 156,250 168,250
10 Trench Steel Plating (tr.ft.) 12,834 0012,834 10 128,340 128,340
11 Splice Vault (ea.) 7 42,000294,0007 20,000 140,000 434,000
12 138 kV XLPE 1750 kcmil cable (ft.) 43,819 401,752,7681,752,768
13 Ground continuity conductor (ft) 14,260 2.535,6508 2,000 16,000 51,650
14 Duct Mandrell Tests 25 4,000 100,000 100,000
15 Cable Installation (section pulls) 24 8,000 192,000 192,000
16 Ground conductor installation (sections) 8 2,000 16,000 16,000
17 138 kV terminations (ea.) 6 8,00048,0006 8,000 48,000 96,000
18 Manufacturer's field supervisor (week) 12 7,000 84,000 84,000
19 Splice and termination special tools (lot) 1 25,00025,00025,000
20 138 kV, 1-phase splices (ea.) 21 9,000189,00021 9,000 189,000 378,000
21 Cross-Bonding Link Boxes 5 8,14037,9875 3,000 14,000 51,987
22 3-Ph Grounding Link Boxes 3 6,27020,9003 1,000 3,333 24,233
23 Cable Clamps 245 13031,850245 100 24,500 56,350
24 Upaved ROW restoration (sq.ft.) 2,852 12,8522,852 1 2,852 5,704
25 Cable Termination Structures 2 52,000104,0002 6,000 12,000 116,000
26 Mob./Demobi. Cable Contractor (ea.) 2 30,000 60,000 60,000
27 Mobile Office/Storage Areas 85,000
28 Traffic Control lot 75,000 75,000
29 Security (man-days) 360 300 108,000 108,000
30 Test & Energization (ea) Lump Amt. 20,000 20,000 20,000
31 Emergency repair parts (lot) 1 102,000102,000 0 102,000
32 Subtotal $3,423,670$4,517,444 $8,026,114
33 Specification Preparation $35,000 $35,000
34 Detailed Engineering (ea.) $397,056 $397,056
35 Surveys (lot) $250,000 $250,000
36 Soil Survey $33,000 $33,000
37 Construction Supervision (days) 360 800 $288,000 $288,000
38 Project Management 300 1200 $360,000 $360,000
39 Field Construction Inspection 360 800 $288,000 $288,000
40 Construction Contingency & Profit (20%) $903,489 $903,489
41 Material Contingency & Profit (15%) $513,551$513,551
Subtotals $3,937,221$7,071,989
42
43 7% $770,645
Sales Tax
$11,864,854
Total Cost
City of University Park, Texas 4 - 25 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
SECTION 5
CONVERSION OF ALLEY AERIAL SERVICES TO UNDERGROUND
CONVERSION OF ALLEY ARIEL
SERVICES TO UNDERGROUND
INTRODUCTION
The City of University Park, Texas is considering the feasibility of converting certain overhead utilities
(electric distribution, telephone, and cable TV) that serve residential customers from the alleys behind the
residences. This could be in conjunction with the City’s “mile-per-year project”, which is an on-going
effort to replace existing underground utility lines (gas, water, and sewer) below the alleys throughout the
City. This Study is based on the premise that the placement of the aerial services underground will occur
concurrently with the reconstruction of the existing underground utilities.
This Study takes into consideration the various service provider’s standards and requirements for placing
their particular utility services underground. Any additional right-of-way easements required will be
addressed. In order to display a proposed layout of the underground services, a typical City block was
selected, which is the block bordered in the north and south by Stanford and Amherst Streets and the east
and west by Hillside Avenue and Airline Road. Opinions of probable cost are developed for the block
area and can be extrapolated for area lengths of more than one block. Two versions of undergrounding
these utilities were considered, the first with all utilities placed underground in the alley and the second
with the electric, cable, and telephone served from primarily the front of each lot. The latter would not
require additional right-of-way in the alley area.
EXISTING RIGHT-OF-WAY
The City’s alleys have utility rights-of-way of various widths with the majority being either 10-feet or 15-
feet wide. The selected block has a 10-foot width. The current underground utilities placed within these
rights-of-way are sewer, water, and gas. The existing overhead utilities are supported by wood poles
which are also located within the rights-of-way. See Figures 5-1 and 5-2 which show a cross section of
the utilities and right-of-way for a 10-foot and 15-foot width, respectively. Figures 5-2 and 5-3 show the
cross section of the utilities plus the sanitary sewer service conditions.
City of University Park, Texas 5 - 1 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
UTILITY REQUIREMENTS
Several meetings and discussions were held with the various entities that would be involved in an alley
underground project. The following indicates each utility and some of the salient points of their
requirements:
1. Sewer - City of University Park:
a. Typically an 8-inch PVC line placed at a depth of 9 to 11 feet below grade.
b. Line will be tapped for each residence, sweeping upward toward each residence
which requires a minimum of 12-inch clearance to other pipes or objects.
2. Water - City of University Park:
a. Typically an 8-inch PVC line placed at a depth of 42 inches below grade.
b. Line will be tapped for service lines to each residence’s water meter.
3. Gas - Atmos Energy:
a. Typically a 2-inch PVC line placed 2 to 3 feet below grade.
b. Line will be tapped with 3/4-inch service line to each residence’s gas meter.
4. Electrical Distribution - TXU Electric Delivery:
a. The primary (15-kV), three-phase distribution circuit is to be placed in the street in
a 2-by-2, 6-inch conduit, concrete-encased duct bank. Cable size and type is 1,000
kcmil EPR with concentric neutral.
b. A four-way or three-way manhole (approximately 12 feet by 12 feet) will be
placed in the street every block and will connect the primary duct bank in at least
two directions, plus the connection to pad-mounted switchgear.
c. The pad-mounted switchgear unit (enclosed in a metal or fiberglass cabinet
approximately 6-feet wide by 6-feet long by 5-feet high) placed at each block will
connect the primary three-phase circuit to a single-phase (15-kV) circuit that will
be fed to a series of pad-mounted transformers. The single circuit line (one 1/0
aluminum, XLPE cable in a 4-inch PVC conduit) will loop through each
transformer in the alley and connect to the adjacent block’s switchgear. (See
example in Figure 5-5.)
City of University Park, Texas 5 - 2 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Figure 5.5
d. Each transformer (assumed to be a 75-kVA unit) will typically serve six
residences. See example in Figure 5-6 which includes (left to right) a cable TV
pedestal, pad-mounted transformer, and telephone pedestal. The 240/120-volt
service drops to each residence will be a three-wire circuit in a PVC conduit. The
transformers have been located so each unit can provide service to two residence
meters and a circuit to a secondary pedestal which will in turn serve four
residences. See Figure 5-7 which shows a cable TV pedestal on the left and an
electric secondary pedestal on the right.
Figure 5-6
City of University Park, Texas 5 - 3 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Figure 5.7
e. Each pad-mounted transformer will require a footprint area approximately 5-feet
deep and 4-feet wide. Working and ventilating clearance to objects is 5 feet with
10 feet required for hot-stick maintenance for the front side. The transformer
orientation would need to have this side facing the alley.
5. Telephone - AT&T:
a. The telephone system for residences will be sourced from a large 1,200-pair cable
or larger which will be connected to a 600-pair cable that will run the length of the
alleys. This connection will be made in a handhole (4-feet by 4-feet wide by 8-feet
by 4-feet deep) or a traffic bearing manhole (6-feet wide by 8-feet long by 6-feet
deep) located near the alley entrance, one per block.
b. The 600-pair cable will be installed in a 4-inch conduit the length of the alley in
each block.
c. A 100-pair cable will also connect in the manhole/handhole and connect to
telephone pedestals by looping in and out for the length of the block. Each
pedestal will provide service to four residences.
6. Cable TV - Charter Communications:
a. The cable TV system for residences will be sourced from a main fiber optic feeder
which will be connected to a trunk fiber optic line that runs the length of the alley
and connects to two amplifier pedestals per block (approximately 600 feet apart).
b. Coaxial cable will then connect to the cable pedestals; each will serve four
residences.
c. The trunk fiber-optic cable and coaxial cables to the pedestals will be installed in a
4-inch PVC conduit which will have three, 1-1/4-inch subducts contained in the 4-
inch conduits.
City of University Park, Texas 5 - 4 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
CONSTRUCTION METHODS
As described above, almost all of the existing aerial facilities would need to be installed under the alley
with the exception of the electrical-distribution, primary, three-phase feeders. Figures 5-1 and 5-2 show
the cross section of required right-of-way and clearances for all the utilities. The construction concept is
that during the replacement of the existing underground utilities (the pipes), the existing overhead utilities
(the wires) would be placed underground utilizing joint-trench participation among the various entities.
Figures 5-3 and 5-4 show the cross section of the proposed underground with the existing sanitary sewer
service for individual residences. Two of these service connections occur for every lot width
(approximately every 50 feet). Likewise, service connections for water and gas will have service
connections that rise from the primary line for each residence’s meter (approximately every 50 feet).
One of the 4-inch conduits for the telephone lines will continue underground for the length of the block.
The other 4-inch conduit would need to rise up to loop into each telephone service pedestal and then
return under ground. These telephone conduit risers would be located approximately every 100 feet.
The cable TV 4-inch conduit which would contain three subducts would also need to turn up and loop
through each amplifier and cable TV service pedestal. These conduit risers would also need to be located
approximately every 100 feet.
Figure 5-8 shows the electric distribution, cable TV, and telephone services emanating from the alley. As
stated earlier, this layout requires additional rights-of-way and easements in the alley and residents'
backyards.
Figure 5-9 shows an alternative to the alley construction by placing the electric-distribution, pad-mounted
transformers and pedestals, and the cable TV and telephone pedestals at the front of the residential lots.
This method would alleviate the need for additional rights-of-way in the backyards, but would require
additional easements in the front yards and along lot lines between houses to be able to route the service
cables to the existing residential connections at the rear of the houses.
City of University Park, Texas 5 - 5 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
ADDITIONAL EASEMENTS AND RIGHT-OF-WAY REQUIREMENTS
As shown on Figures 5-1 through 5-4, to allow for the placement of the wire utilities underground,
additional rights-of-way would be required to allow for these additions to meet the necessary clearance
requirements for construction and maintenance. The figures show that a width of 20 feet would be
required. Additional rights-of-way will be required along the line route in the alley between Stanford and
Amherst for 11 blocks and in the alley between Daniel and University for two blocks. Approximately
92,400 square feet of additional rights-of-way was calculated for the alleys.
With the additional rights-of-way available, most of the pad-mounted equipment, including telephone
pedestals, cable amplifiers, cable pedestals, and electrical-distribution secondary pedestals, would need to
be located in this area outside the paved-alley driving surface. Additional easements may be required for
placement of the larger pad-mounted electrical equipment, including the pad-mounted switchgear cabinets
and the pad-mounted transformers. The transformers require a much larger area than the service
pedestals. As indicated earlier in the Study, the footprint size plus the operating clearance distances, an
area of approximately 14-feet wide and 10-feet deep, would be required for each transformer. Additional
rights-of-way required for the transformers and pad-mounted switchgear would be approximately 780
square feet.
OPINION OF PROBABLE COST
An opinion of probable cost was developed for the material and installation of the aerial utilities
underground in conjunction with replacing the existing underground sanitary sewer, gas, and water
utilities and placing underground in the alley. These costs include only the incremental costs for the
electrical, cable, and telephone. These costs were developed based on the single block illustrated on
Figure 5-8. The cost per block is approximately $832,000. The cost for the portion of the utilities
currently under the Greenville - Loma Alto transmission line is approximately equivalent to 10 blocks,
thus a cost of approximately $8,320,000. The cost for purchasing additional rights-of-way for the alley
underground construction plus pad-mounted equipment requirements along the line route is
approximately $6,036,000, based on a $60-per-square-foot cost.
City of University Park, Texas 5 - 6 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Figure 5-9 shows a layout with the service pedestals and transformers located at the front of the lots. The
cost per block would be approximately $900,000 due to the longer feeder cable and service drops. The
total line route cost would be approximately $9,000,000. This would not require additional rights-of-way
in the alley, but would require more in the front of the lots and along lot lines between houses. The
approximate cost would be $12,829,200 again based on a $60-per-square-foot cost.
City of University Park, Texas 5 - 7 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study
Opinion of Probable Cos5/22/200
t6
Front Sheet
Job Name:University Park, TX UG Util / Alley Rev. 0Estimator:Andy Haun
Start date:01/01/07End date:04/01/07Date:05/22/06
Duration:13WeeksLocation:University Park, TX
Bid DateExpires:3-Sep-06
Labor:Bidders:
First Shift:
Regular rate4,765hrs @$53.85$256,61
8
Overtime rate (diff)0%0 hrs @$18.45$0
Premium rate (diff)5%238 hrs @$36.89$8,780
Subtotal:$265,398
Labor Efficiency$265,398@10.00%$26,540
Subtotal:$291,938
Supervision5.00%$14,597
Subtotal:$306,535
Rate Increase100%$306,535@3.00%$9,1965.6% Per Year
Subtotal:$315,731
Total Labor Cost$315,731
Material$216,662
Escalation ($3.00 Copper)$216,662@10.0%$21,666
Subtotal:$238,328
Sales tax6.9%$16,445
Subtotal:$254,773
MBE Participation$0@2.0%$0
Subtotal:$254,773
Total Material Cost$254,773
$1.352
Job Expenses:
Tools/Equipment$6,314
Site Superintendent$37,866
Documentation$0
Safety$2,350
Subtotal:$46,530% of L&M
Total Job Expense$46,530
8.16%
Sub Total Job Cost$617,034
Contractor Overhead & Profit15.0%$92,555
Engineering10.0%$61,703
Estimating Contingency10.0%$61,703
Subcontractors$0
$0
Subtotal:$0
Total SubcontractorsMarkup10.0%$0
BondingSubtotal:$00.72%$0
TOTAL:$832,995
Distribution Rates:
Labor:4765 hrs @$113.339Distr rate$540,068
Material:$216,662@$1.352Distr rate$292,927
Expenses$46,530@$1.150Distr rate$53,510
Subcontractors:$0@$1.100Distr rate$0
TOTAL: $832,995
Base:$832,995
Difference:$0
File: UnivParkUGUtilAlley0506 / Front Sheet
5/22/2006 3:36 PM
Opinion of Probable Cos
t
Basic Field Cost
s
University Park, TX UG Util / Alley Rev. 5/22/200
Job Name:06
University Park, T
Location:X
Projected
StartEnd
01/01/0704/01/0790Cal. days
64Wk. days
13Weeks
RATES:
Average manpower
:4,765hrs +10%5,242hrs (incl lost time)
Single shift:8 hrs per day10men
1-Shift 10 Hr10 hrs per day10men
Double shift:20 hrs per day4men
Present wage rates:Expire:
3-Sep-06JWFMGF
FIRST SHIFT:
Straight time:$53.854$57.789$59.764
LU#124 - MOOvertime:$72.300$78.035$80.911
Kansas City, MOPremium:$90.745$98.282$102.058
SECOND SHIFT:
Journeyman:$0.000$0.000$0.000
Differential to ST:($53.854)($53.854)($53.854)
Supt. Rate:
Regular rate:40hrs @$59.764$2,390.56
LU#124 - M
OOvertime rate:5hrs @$80.911$404.56
Kansas City, MOPremium rate:0hrs @$102.058$0.00
KC GF Rate
Weekly Subtotal:$2,795.12
Second shift:0%@7.47%$0.00
Weekly Subtotal:$2,795.12
Average cost:45hrs work week:$62.11(per hour)
JOB EXPENSES:% of Labor & Material: 8.16
%
Administrative Costs
:
Supt living:0wks @$450$0
Supt wages:13wks @$2,795$35,937
Supt truck:13wks @$150$1,929
Added supt:0wks @$2,795$0
Added truck:0wks @$150$0
Office trailer:0mo @$500$0
Office utilities:0mo @$200$0
PM travel:0trips$300$0$37,866
Documentation
:Engineering:0hrs @$65$0
Drafting:0hrs @$45$0$0
Safety Costs:
Safety equip:10men@$135$1,350
Drug Testing10men@$50$500(1.5 hrs)
Safety Meeting10hrs @$50$500$2,350
Miscellaneous
:
Expendables1.0%labor$315,731$3,157
Small tools1.0%labor$315,731$3,157
Lift delivery0@$125.00$0
65' Genie0mo@$2,050.00$0
45' Genie0mo@$1,200.00$0$6,314
TOTAL EXPENSES:$46,530
File: UnivParkUGUtilAlley0506 / Expenses
5/22/2006 3:37 PM
Opinion of Probable Cost
05/22/06
Distribution Sheet
Job:University Park, TX UG Util / Alley Rev. 0Labor$113.339
City:University Park, TXMaterial$1.352
Subs$1.100
PROPOSAL BREAKDOWN:
ItemDescriptionLaborMaterial
HrsSellCostSellTOTAL
115kV Power921$104,372$130,194$176,022$280,394
2120/240V Power1,266$143,435$31,587$42,706$186,141
3Telephone1,491$169,007$27,671$37,411$206,418
4Cable TV847$96,053$25,210$34,085$130,138
5Electrical Power and Comm System Startup240$27,201$2,000$2,704$29,905
6Gas0$0$0$0$0
7Water0$0$0$0$0
8Sanitary Sewer0$0$0$0$0
9Pavement Removal and Replacement0$0$0$0$0
1000$0$0$0$0
1100$0$0$0$0
1200$0$0$0$0
1300$0$0$0$0
1400$0$0$0$0
1500$0$0$0$0
1600$0$0$0$0
Grand Totals4,765$540,068$216,662$292,928$832,996
Front sheet totals:4,765$540,068$216,662$292,927$832,995
Difference:0$0$0($1)($1)
File: UnivParkUGUtilAlley0506 / Distribution
5/22/2006 3:37 PM
Sega, Inc.
05/22/06
Opinion of Probable Cost
Takeoff Sheets
University Park, TX UG Util / Alley Rev. 0
1Sheet:15kV Power
LaborLaborMaterialMaterial
QuantityDescriptionPerPer
UnitExtensionUnitExtension
Ductbank at Lot Front
1,200Excav/Bkfil Unit Labor & Equip at 50' per hour2.00c24.00$75.00c$900.00
2,4006"PVC6.75c162.00$194.00c$4,656.00
120 - 6" PVC Coupling0.35e42.00$8.00e$960.00
240 - 6" PVC Chairs0.18e43.20$1.40e$336.00
4 - 6" Elbows GRS3.75e15.00$250.00e$1,000.00
1,200Concrete per ft 2'x2' Ductbank at $75 per CYe$11.11e$13,332.00
1Prefabricated Manhole16.00e16.00$5,000.00e$5,000.00
Extend Ductbank to Padmt Sw
120Excav/Bkfil Unit Labor & Equip at 50' per hour2.00c2.40$75.00c$90.00
1206"PVC6.75c8.10$194.00c$232.80
6 - 6" PVC Coupling0.35e2.10$8.00e$48.00
12 - 6" PVC Chairs0.18e2.16$1.40e$16.80
4 - 6" Elbows GRS3.75e15.00$250.00e$1,000.00
120Concrete per ft 2'x2' Ductbank at $75 per CYe$11.11e$1,333.20
1S&C PMH-Series 15kV Padmt Switch Complete32.00e32.00$16,000.00e$16,000.00
Ductbank for Alley Distribution
80Excav/Bkfil Unit Labor & Equip at 50' per hour2.00c1.60$75.00c$60.00
1204" PVC4.50c5.40$159.59c$191.51
6 - 4" PVC Couplings0.19e1.14$5.00e$30.00
12 - 4" PVC Chairs0.13e1.56$1.00e$12.00
4 - 4" Field Bends1.20e4.80$5.00e$20.00
1,280Concrete per ft 1'x1' Ductbank at $75 per CYe$5.56e$7,116.80
Feeder Cable & Terminations
4,09215kV 1000MCM Al URD EPR/CPE 1/3N80.00m327.36$13,900.00m$56,878.80
1,50015kV 1/0AWG Al URD EPR/CPE 1N25.00m37.50$3,900.00m$5,850.00
8 #1000 15KV Termination Stress Cone6.00e48.00$100.00e$800.00
2 #1/0 15KV Termination Stress Cone2.50e5.00$85.00e$170.00
Transformers including C. Riser & 15kV Term
875kVA 15kV:120/240 6.00e48.00$1,500.00e$12,000.00
8 - 10' x3/4'' Ground Rod1.50e12.00$18.00e$144.00
484" PVC4.50c2.16$159.59c$76.60
16 - 4" Field Bends1.20e19.20$5.00e$80.00
12815kV 1/0AWG Al URD EPR/CPE 1N25.00m3.20$3,900.00m$499.20
16 #1/0 15KV Termination Stress Cone2.50e40.00$85.00e$1,360.00
Note: Excludes Concrete/Ashpalt Cut/Patch
TOTALS:
920.88$130,194
Project: UnivParkUGUtilAlley0506 / Takeoff
5/22/2006 3:37 PM
Page 1 of 6
2Sheet:120/240V Power
LaborLaborMaterialMaterial
QuantityDescriptionPerPer
UnitExtensionUnitExtension
120/240 Extensions to Pedestals (8 avg. 60')
8120/240V Distribution Pedestal8.00e64.00$75.00e$600.00
4804" PVC4.50c21.60$159.59c$766.03
16 - 4" Field Bends1.20e19.20$5.00e$80.00
1,920500MCM XHHW44.00m84.48$3,443.29m$6,611.12
48500MCM termination0.70e33.60$22.39e$1,074.72
640#4 XHHW14.00m8.96$381.57m$244.20
16#4 termination0.35e5.60$3.00e$48.00
(Share Alley Excav/Bkfil w/ 15kV Ductbank)
Service Drops (46 avg. 60')
2,7601 1/2 " PVC2.75c75.90$50.09c$1,382.48
184 - 1 1/2" Field Bends1.15e211.60$5.00e$920.00
46 - 1 1/2" Male Adaptors0.20e9.20$2.50e$115.00
3681 1/2" GRC12.00c44.16$344.13c$1,266.40
46 - 1 1/2" Myers hubs0.50e23.00$3.45e$158.70
92 - 1 1/2" Conduit supports0.18e16.56$4.30e$395.60
11,040#3/0 XHHW26.00m287.04$1,188.71m$13,123.36
276#3/0 termination0.90e248.40$8.17e$2,254.92
3,680#6 XHHW13.00m47.84$249.01m$916.36
92#6 termination0.30e27.60$2.72e$250.24
1,840Excav/Bkfil Unit Labor & Equip at 50' per hour2.00c36.80$75.00c$1,380.00
(Use Backhoe to Share Excav/Bkfil w/ T & C)
Note: Excludes Concrete/Ashpalt Cut/Patch
TOTALS:
1265.54$31,587
Project: UnivParkUGUtilAlley0506 / Takeoff
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Page 2 of 6
3Sheet:Telephone
LaborLaborMaterialMaterial
QuantityDescriptionPerPer
UnitExtensionUnitExtension
Trunk Line in Alley
2Prefabricated Pavement-rated HandHole8.00e16.00$2,000.00e$4,000.00
12Telephone Distribution Pedestal4.00e48.00$150.00e$1,800.00
2,6004" PVC4.50c117.00$159.59c$4,149.34
16 - 4" Field Bends1.20e19.20$5.00e$80.00
28 - 4" Male Adaptors0.35e9.80$4.00e$112.00
1,300Telephone 600 pr Cable40.00m52.00$6,000.00m$7,800.00
1,300Telephone 100 pr Cable25.00m32.50$3,000.00m$3,900.00
3001PR #20 Termination (one end )2.50e750.00$0.75e$225.00
Service Drops (46 avg. 60')
2,7601" PVC2.00c55.20$29.57c$816.13
184 - 1" Field Bends1.00e184.00$5.00e$920.00
46 - 1" Male Adaptors0.15e6.90$2.00e$92.00
3681" GRC8.00c29.44$203.21c$747.81
46 - 1" Myers hubs0.40e18.40$2.54e$116.84
92 - 1" Conduit supports0.12e11.04$2.25e$207.00
2,760Tray Cable FREP/CPE #16 Shld 4PR18.00m49.68$880.00m$2,428.80
924PR #16 Termination (one end )1.00e92.00$3.00e$276.00
Note: Excav/Bkfil incl with Elec Power
TOTALS:
1491.16$27,671
Project: UnivParkUGUtilAlley0506 / Takeoff
5/22/2006 3:37 PM
Page 3 of 6
4Sheet:Cable TV
LaborLaborMaterialMaterial
QuantityDescriptionPerPer
UnitExtensionUnitExtension
Trunk Line in Alley
2Prefabricated Pavement-rated HandHole8.00e16.00$2,000.00e$4,000.00
10Cable Distribution Pedestal4.00e40.00$150.00e$1,500.00
2Cable Distribution Pedestal / Amplifier6.00e12.00$2,500.00e$5,000.00
1,3004" PVC4.50c58.50$159.59c$2,074.67
8 - 4" Field Bends1.20e9.60$5.00e$40.00
14 - 4" Male Adaptors0.35e4.90$4.00e$56.00
1,300Thick-net Coax Cable25.00m32.50$4,000.00m$5,200.00
28Coaxial Cable 59/U Terminations2.50e70.00$2.50e$70.00
Service Drops (46 avg. 60')
2,7601" PVC2.00c55.20$29.57c$816.13
184 - 1" Field Bends1.00e184.00$5.00e$920.00
46 - 1" Male Adaptors0.15e6.90$2.00e$92.00
3681" GRC8.00c29.44$203.21c$747.81
46 - 1" Myers hubs0.40e18.40$2.54e$116.84
92 - 1" Conduit supports0.12e11.04$2.25e$207.00
2,760Thin-net Coax Cable25.00m69.00$1,500.00m$4,140.00
92Coaxial Cable 59/U Terminations2.50e230.00$2.50e$230.00
Note: Excav/Bkfil incl with Elec Power
TOTALS:
847.48$25,210
5Sheet:Electrical Power and Comm System Startup
LaborLaborMaterialMaterial
QuantityDescriptionPerPer
UnitExtensionUnitExtension
1Power and Signal System Testing160.00e160.00$2,000.00e$2,000.00
1Coordinate Outages and Changeovers80.00e80.00e
TOTALS:
240.00$2,000
Project: UnivParkUGUtilAlley0506 / Takeoff
5/22/2006 3:37 PM
Page 4 of 6
6Sheet:Gas
LaborLaborMaterialMaterial
QuantityDescriptionPerPer
UnitExtensionUnitExtension
Distribution Line
1,300Excav Unit Labor & Equip at 50' per hour2.00c26.00$75.00c$975.00
1,300Backfill Unit Labor & Equip at 100' per hour1.00c13.00$200.00c$2,600.00
2Connection to Existing Gas Distributione$2,000.00e$4,000.00
1,300Gas Distribution Line, 2" PEe$3.37e$4,381.00
Service Drops (46 avg. 60')
46Tee Connectione$70.00e$3,220.00
46Service Valvee$165.00e$7,590.00
2,760Gas Distribution Line, 1/2" PEe$2.29e$6,320.40
46Connection to Existing Metere$70.00e$3,220.00
Note: Unit Costs from Means Bldg Cost Data
TOTALS:
7Sheet:Water
LaborLaborMaterialMaterial
QuantityDescriptionPerPer
UnitExtensionUnitExtension
Distribution Line
2Connection to Existing Water Distributione$1,000.00e$2,000.00
1Valve & Connection Lump Sume$230.00e$230.00
1,300Water Distribution Line, 8" PVCe$17.58e$22,854.00
Service Drops (46 avg. 60')
46Tee Connectione$195.00e$8,970.00
2,760Water Distribution Line, 1" PVCe$1.49e$4,112.40
46Connection to Existing Metere$195.00e$8,970.00
Note: Excav/Bkfil incl with Gas Distribution
Note: Unit Costs from Means Bldg Cost Data
TOTALS:
Project: UnivParkUGUtilAlley0506 / Takeoff
5/22/2006 3:37 PM
Page 5 of 6
8Sheet:Sanitary Sewer
LaborLaborMaterialMaterial
QuantityDescriptionPerPer
UnitExtensionUnitExtension
Distribution Line
2Connection to Existing Linee$1,000.00e$2,000.00
1,300Sanitary Sewer Line, 8" PVCe$7.94e$10,322.00
Service Drops (46 avg. 60')
46Connection to Linee$620.00e$28,520.00
Note: Excav/Bkfil incl with Gas Distribution
Note: Unit Costs from Means Bldg Cost Data
TOTALS:
9Sheet:Pavement Removal and Replacement
LaborLaborMaterialMaterial
QuantityDescriptionPerPer
UnitExtensionUnitExtension
1Lump Sum Estimate for Alleye$50,000.00e$50,000.00
1Lump Sum for Misc. Sidewalks & Drivese$20,000.00e$20,000.00
TOTALS:
Project: UnivParkUGUtilAlley0506 / Takeoff
5/22/2006 3:37 PM
Page 6 of 6
Sega, Inc.
Opinion of Probable Cost
Distribution
Job:University Park, TX UG Util / Alley Rev. 0
City:University Park, TX
Cost Breakdown:
ItemDescriptionLaborMaterialTotal
115kV Power$104,372$176,022$280,394
2120/240V Power$143,435$42,706$186,141
3Telephone$169,007$37,411$206,418
4Cable TV$96,053$34,085$130,138
5Electrical Power and Comm System Startup$27,201$2,704$29,905
6Gas$0$0$0
7Water$0$0$0
8Sanitary Sewer$0$0$0
9Pavement Removal and Replacement$0$0$0
100$0$0$0
110$0$0$0
120$0$0$0
130$0$0$0
140$0$0$0
150$0$0$0
Grand Totals$540,068$292,928$832,996
Note: Breakdowns include 15% O&P, 10% Engineering, and 10% Contingency
File: UnivParkUGUtilAlley0506 / Distribution
5/22/2006 3:37 PM
SECTION 6
CONCLUSIONS
CONCLUSIONS
Sections 3, 4, and 5 consider the various transmission and utility alternatives independently. The
following table summarizes various combinations of alternatives ranging from rebuilding the existing line
to the existing design parameters to placing transmission, distribution, and telecommunications utilities
underground.
City of University Park, Texas 6 - 1 Sega Project No. 06-0069
138-kV Underground Transmission Feasibility Study