Eastern Transmission Line
Introduction to the Eastern Transmission Line
Since 2005, Your Own Utilities has been working on the approved City Commission route for the Eastern Transmission Line. This line is important to our community in order to increase electric reliability in the eastern part of Tallahassee, where development has outpaced construction of electric transmission lines and substations.
The approved route, referred to as the "Welaunee route" in the Commission Agenda Item, was recommended by staff as the most viable of three alternatives based on the following criteria: public input, reliability, economics, impact on community and environmental concerns.
The Welaunee route runs overhead along Mahan Drive to Buck Lake Road, then underground north along Dempsey Mayo Road; then, using both overhead and underground installations through Welaunee property. At I-10 the route travels north to a new substation 14 to be built near Centerville and Shamrock Roads. Where the route intersects I-10, it will also run east down I-10 (pending approvals) to a new substation 17 to be built near Mahan Drive/US 90 just past its intersection with I-10.
Construction on Phase I of the project is mainly complete with the exception of the work to be done inside the new substations. This work continues. The first of three new substations is planned to be energized in the Spring of 2011 (BP21). Testing of the underground installations will need to be completed prior to the substation completion.
If you have any questions about the Eastern Transmission Line routes and other
information, please contact Paul DeFrank.
Whitetail Pass Access Detail Drawing (PDF)
Transmission Line Construction Impacts
As stated in the Consultant's report, "An overhead line can generally
span and not disturb sensitive features such as cultural resources sites,
streams, most wetlands, isolated steep slopes, a sensitive species location,
etc. Undergrounding however, requires construction of a trench and results
in a disturbed area of approximately 40' in width for the entire length of
the line" (see pictures of underground
projects). Even with direct boring construction, there is an area of
disturbance of approximately 40'-50'W X 100'-150'L due to the installation
of a vault and room for cable pulling and conduit installation equipment
Transmission lines have very high reliability because of their physical design
and the fact that most transmission lines are in a "loop" configuration
that provides a back-up source if one of the transmission lines experiences
an outage. The City's transmission system has experienced only 2 significant
outages in the last 17 years. One of these incidents was related to Hurricane
Kate and the other was caused by a tree in the late 1990's. The outage that
occurred in the late 1990's resulted in power restoration to the transmission
grid within thirty minutes. If an outage occurs on an underground transmission
line to this substation, the line could be out for weeks. Since this will
be the only feed to the substation for some time, this will mean that a portion
of the City's customers may be without power for this same period of time.
Another point that is commonly mentioned with respect to underground electric
facilities is that trees no longer have to be trimmed or cut in order to
maintain an appropriate, safe clearance for an overhead line. Therefore,
not only is the annual expense of tree trimming saved, but also the aesthetic
value of the tree is saved. There are avoided tree trimming maintenance costs
associated with underground installations. However, while trimming trees
for overhead lines may create an impact on the crown of a tree, underground
lines may affect the root structure of a tree. Since the majority of roots
are within the top four feet of the soil, significant damage can occur to
any tree with open-trench construction. At least a portion of the tree can
be killed, depending upon circumstances. In order to minimize the impact
to a tree, "trenchless" construction (boring) can be done on this
project. Boring a hole through the root of a tree does reduce, but not eliminate,
the impact on the tree; however, this is at an additional expense for this
project of 1.63 times the cost of the open trench construction.
Maintenance Cost Benefits
In many cases there is an expectation that the economic benefits associated
with underground electric installations are significant enough to offset
the additional cost of those facilities. Unfortunately, the economic benefits
associated with underground electric facilities are, in most cases, minimal
compared to the difference in the cost of installation.
The most quantifiable savings associated with the installation of underground
transmission facilities compared to overhead transmission facilities is the
reduction of exposure to the trees that must be trimmed on a regular cycle.
For every mile of line the City installs underground, the reduced overhead
electric transmission facility exposure reduces the City's tree trimming
cost by approximately $7,300 annually. For every million-dollar increase
per mile in construction costs to support underground construction, the City
would incur approximately an additional debt service cost of $65,000 per
year for 30 years. In addition, when underground facilities require maintenance,
their costs are significantly higher than that of overhead facilities.
Minimum Corridor Widths
Underground Construction (Open Trench) 40' (25' permanent, 15' temporary) Underground Construction (Direct Bore) 10'
Wide (no above ground disturbance). However, every 2000' along the route, there
is an area of disturbance of approximately 40'-50'W x 100'-150'L due to the
installation of a vault and room for cable pulling and conduit installation
Regardless of the underground construction method used, the Vaults that
would be needed for this project are 10' W x 24' L.
Overhead Construction (Mahan Drive) 22' Wide Overhead Construction (on Welaunee
Property) 100' Wide.
Over the last decade, the City has experienced significant growth
and development, and a corresponding increase in the demand for electricity.
This has been especially true in the fast growing eastern portion of the City
and adjacent Leon County where development has outpaced the construction of
electric transmission lines and substations. The currently inadequate transmission
and substation network in this large and rapidly growing part of the City's
service area creates a reliability concern.
As a standard design practice for reliability, residential and commercial customers
electricity needs should be able to be supplied from a number of alternative
substations in the area when a major outage occurs. These alternative substations
are all linked together by a transmission line network. When major outages occur,
the City must currently rely on the lower voltage distribution system to keep
the power flowing to its customers. This lower voltage system has capacity limits,
which means we would not be able to keep an uninterrupted flow of power to this
area in the event of a major outage. Further, much of this system is currently
served by a one-way feed from distant substations, so that a distribution line
failure would effectively leave all customers beyond that point without power
until the cause of the outage was found and repaired. This level of service is
not consistent with our customers' needs or expectations.
The only acceptable and permanent way of providing a reliable source of electricity
and providing for continuing growth to the eastern part of Tallahassee is to
reinforce this area with the proper substation and transmission infrastructure.
This infrastructure cannot wait any longer. A temporary substation has already
been constructed, and now an additional distribution feeder is needed to support
the area load. Growth on the electric system continues and the load is
projected to increase at a rate of approximately 3 percent per year in the
Considering that substations in the east part of the service territory are approaching
maximum load, major problems are likely to occur during extreme peak load periods
in the eastern parts of the City's service territory until the proposed substation
and transmission lines are in service.
Initial Work began on the Mahan Route in 2001.
City Commission approved the construction of an overhead transmission line
along Mahan Drive -
June 13, 2001.
However, after further consideration of the fact that Mahan serves as a
major gateway into the city, and based on the desire to get additional citizen
involvement, the construction was postponed until an Independent Route Study
could be conducted.
A Route Study was conducted by EDAW/Exponential Engineering Co. from June
2002 to June 2003.
Public Workshops were held on August 27, 2002 and April 22, 2003, after
7600 notices were mailed to the neighborhoods, notices were published in
the Tallahassee Democrat and signage was provided in the impacted area.
Public Comments were recorded at both workshops, and the comment period
after second workshop was extended until May 26, 2003 to provide additional
time for responses.
At the request of the neighborhoods, City Electric Utility staff attended
and made presentations at the October 24, 2002 Buck Lake Alliance annual
Homeowners meeting, the January 7, 2003 Meadow Hills Homeowners meeting,
and the October 9, 2003 Buck Lake Alliance annual Homeowners meeting.
The Final Report from the route consultant was submitted to the City in
late September 2003.
The route consultant recommended Route N as the preferred route to carry
forward. Route F was the route consultant's second highest recommended preferred
route (see attached Route Map).
In mid-November, approximately 7600 postcards were mailed to residents notifying
them of the consultant's recommendation, staff's recommendation of Route
A, and the intent to present an agenda item to the City Commission requesting
approval of the staff's recommended route.
At the December 10, 2003 meeting, the City Commission gave conceptual approval
of Route A with the understanding that a third public workshop would be held
on January 6, 2004, the results of which would be presented at the January
14, 2004 City Commission meeting.
City Staff met with Leon County Staff regarding Leon County Commission concerns
On December 11, 2003, City Staff issued an open invitation to Leon County
Commissioners for individual briefings prior to the third Public Workshop
scheduled on January 6, 2004; Commissioners Thaell and Rackleff accepted
the invitations and were provided detailed briefings.
A third Public Workshop was held on January 6, 2004 after 7600 notices were
mailed to residents, as along with a corresponding press release being issued.
A summary of the third Public Workshop was provided to the City Commission
for consideration of staff's recommended route on January 14, 2004. The City
Commission voted to accept staff's recommendation of Route A, effective January
29, 2004 to allow for further interaction with the Leon County Commission
relating to their concerns.
On January 28, 2004, the City Commission voted to defer the effective date
of their approval to March 1, 2004 and to conduct a Public Hearing on February
On February 4, 2004 Commissioner Katz and City Staff met with leaders of
neighborhood associations impacted by Route A (Mahan Dr.). During this meeting
another alternate route was identified that followed Route A to Dempsey Mayo,
then north on Dempsey Mayo to a point just north of the Miccosukee Greenway,
parallel to the Greenway to a point that the line could be routed back southeast
to the substation (this proposed route has been identified as Route AMG).
On February 5, 2004 Electric Utility staff participated in a community meeting
on the project hosted by the Buck Lake Alliance to provide further information
to the effected residents and encourage dialogue regarding the proposed routes.
On February 11,2004 the City Commission held a public hearing on the route
selection for Eastern Transmission Line, and voted 5-0 to delay the decision
for no more than four months to allow for further exploration of Route AMG
and alternatives for underground construction of Route A (Mahan Drive). The
Commission limited further exploration of alternatives to these two routes
with flexibility for variations. During this discussion the Commission discussed
the increased probability for potential power outages in the eastern part
of the electric system by extending the length of time for a final decision,
and the need for public involvement relating to the proposed Miccosukee Greenway
On March 29 ,2004 at a City Commission Workshop Retreat, the Commission
appointed Commissioner Katz as the lead Commissioner on this issue. Representatives
of Powerhouse, Inc. immediately responded to the City's request, through
a series of meetings and negotiating sessions, with a proposal where the
City would acquire a combination of easements and fee simple ownership of
a portion of Welaunee property. The conceptual agreement provides an alternative
for the Eastern Transmission Line.
On September 8, the Commission voted 5-0 to approve a conceptual agreement
to purchase +/- 450 acres from Powerhouse, Inc. in the amount of $9,852,000
and to continue the evaluation of the location of the Eastern Transmission
Line subject to the completion of the land transaction.
Staff has also participated in several meetings and discussions with the
Save Our Gateway (SOG) citizens group that represent a broad spectrum of
the community concerned with the location of the transmission line on Mahan
Drive. Based on a significant amount of review, the SOG group had identified
a construction alternative for the Mahan Drive route that is a combination
of overhead construction, "bored", and "open trench" underground
The new alternative gives the city three feasible routes to consider: (1)
Overhead Construction on Route A as originally proposed, (2) Overhead and
combinations of underground construction along Route A as proposed by SOG
and (3) Route AMG as negotiated with Powerhouse, Inc.
On October 11, 2004, Electric Utility staff held a public workshop at W.T.
Moore Elementary School to provide information and seek comments from residents
adjacent to the newly identified Welaunee route.
At the request of members of the Buckhead Homeowner's Association, on October
17, 2004 Commissioner Katz and Staff met with their Board to discuss specific
issues regarding the Eastern Transmission Line relating to the Buckhead Subdivision.
Commissioner Katz and city staff met with Welaunee representatives following
the meeting to try to re-negotiate the width of the tree buffer between Buckhead
residents' houses and the transmission line, per the homeowners' request
The negotiations resulted in an increase in the natural buffer.
Commissioner Katz and city staff attended a meeting of the Buckhead Homeowners
Association January 11, 2005, to present the new plans.
Final options to be presented to the City Commission in February will be
displayed for the public at an open house community meeting Wednesday, February
2, from 5:30 to 7:30 p.m. at W.T. Moore Elementary School.
After more than a year of public involvement initiatives and planning, the
Tallahassee City Commission unanimously approved a route for the new Eastern
Transmission Line at its meeting February 9, 2005.
The approved route, referred to as the "Welaunee route" in the Commission
Agenda Item, was recommended by staff as the most viable of three alternatives
based on the following criteria: public input, reliability, economics, impact
on community and environmental concerns.
What is an EMF?
EMF is an acronym for Electromagnetic Field.
What does it do?
In an electromagnetic field there are actually two fields created: an electric
field and a magnetic field. The strength of the electric field depends on
the voltage being carried, while the magnetic field strength depends on the
amount of current being carried (amperage). While it is easy to shield against
the electric current, it is much more difficult to shield against magnetic
Are there health concerns?
For decades, debate has been
wide spread in regard to the health factors associated with transmission
lines and exposure to EMF. Based on the totality of the evidence available,
there seems to be no conclusive evidence that residential exposure to electric
and magnetic fields produce cancer. Below are links to highly regarded institutions
and their research findings about EMF including the Medical College of Wisconsin,
the National Academy of Sciences, and the National Cancer Institute.
Do I have EMFs in my Home?
Electric charges create electric fields. Electric charges which move (i.e.,
electric current) create magnetic fields. An appliance that is plugged in,
and therefore connected to a source of electricity, has an electric field
even when the appliance is turned off. To produce a magnetic field, however,
the appliance must be not only plugged in, but also operating, so that the
current is flowing.
The electric current we use in our everyday lives produces certain kinds of
electric and magnetic fields. There are many other kinds of electric and magnetic
fields as well, found throughout nature. The term "electromagnetic" field
implies that the electric and magnetic fields are interrelated.
These fields can be characterized by either their wavelength or their frequency,
which are related. The wavelength describes how far it is between one peak
on the wave and the next peak. The frequency, measured in hertz, describes
how many wave peaks pass by in one second of time.
What does State Law say?
Florida State Statute 62-814.450 (3) requires that "the maximum electric
field at the edge of the transmission line Right of Way or at the property
boundary of a new substation shall not exceed 2.00kV/m" (kilovolts/meter).
It further requires that " the maximum magnetic field at the edge of
a 230kV or smaller transmission line Right of Way or at the property boundary
of a new substation serving such lines shall not exceed 150 milliGauss. The
City of Tallahassee is responsible for meeting these standards, and these
guidelines are strictly adhered to throughout our electrical system.
Common Transmission Line Examples
|Above Ground Images
|Concrete pole along Stadium Drive West just north of the Church of Jesus
Christ of Latter Day Saints - this is the most common pole to be
used on the project. This is known as a tangent pole.
|The top four lines constitute a total transmission line. The top line actually is called a "static" wire (usually suspended from a pole by a bolt approximately six inches from the top). Its main purpose is to protect the energized lines from lightning strokes. The other three lines (suspended from insulators that are attached to the pole via steel arms) each carry a phase of the transmission circuit.
|Concrete pole along Stadium Drive in front of the FSU Stadium-Here is the more common design of pole that will be used to change directions on this Eastern Transmission Line project. The pole is concrete. It can be used with "guy wires" and sometimes without.
|Steel pole at the corner of Miccosukee Rd. and Medical Drive- This is a type of pole used for changing the direction of transmission lines. In this case, the line turns from east-west to north-south. While the overall majority of poles for the Eastern Transmission Line Project will be concrete construction, some steel will be necessary.
|Concrete Encasement of Duct Bank
|Transmission Manhole Installation
Width of manhole is 20'.
Width of hole is 32'.
Manholes for the Eastern Transmission Line Were concluded to be smaller
than this, 10' X 24'.
|Typical Cable Reel
|Typical Rigging Installation for
|Typical Cable Pulling Installation-
Setup distance from front of truck to manhole is 60'.
Welaunee Concept Photos
During the previous workshops that the Electric Utility has conducted on
this project, interested customers have requested information about what
a transmission line would look like along the proposed routes. In preparation
for the final workshop on February 2, Your Own Utilities obtained the services
of PhotoScience, Inc. to travel to Tallahassee, take a number of shots along
the proposed routes and provide simulations of what these same photos would
look like after a transmission line is constructed.
All of these are a representation of the concepts that have been developed
by Your Own Utilities with customer comments taken into consideration. Each
of the links below will open up an Adobe
Acrobat file that shows a "before" and "after" shot
for one location. The "Proposed View" is the simulation of the transmission
line at that location. In the cases in which a yellow circle or arrow has been
inserted in this view, it is there to assist the viewer in locating the line
or pole simulation.