Project update: April 2017
Tacoma Power is planning to replace the lattice towers and power transmission line on North 21st Street in 2018. They will be replaced with steel poles and a new transmission line.
The new locations of the towers will allow the City of Tacoma to add things like turn lanes, sidewalks and bicycle lanes down North 21st Street at some point in the future.
What’s included in the tower replacement project?
The 19 aging lattice towers on and near North 21st Street will be replaced with 12 steel poles on every other block. As part of the project, Cushman Substation will be disconnected from the electrical system.
What is the tentative project schedule?
- Design and permitting: Ongoing through 2017
- Construction: April 2018 through the fall of 2018
- Cushman Substation: The substation was deactivated in the fall of 2016, which means some of its automated functionality was turned off. It’s still an energized, functioning component of the utility’s power system. The equipment and structures within Cushman Substation fence will be removed at the end of 2018.
Why do the towers need to come down?
The lattice towers are over 90 years old and in a state of significant deterioration.
How many towers are there now, and how many will there be when the project is complete?
There are now 19 total towers: one on every block of North 21st from North Adams to North Highland (total of 15); two in nearby Westgate Center; one near Cushman Substation; and one in front of Pearl Substation on Pearl Street. Those towers are about 75 feet tall.
They will be replaced with 12 galvanized steel monopole towers: one every other block of North 21st Street (total of nine); two in Westgate Center; and one at Pearl Substation. The new towers range from 100 to 110 feet tall.
In addition, some of the wooden poles that line the sides of 21st Street from Puget Sound Avenue to Proctor will be replaced with taller wood poles.
If the City Council approves a nomination to the Tacoma Register of Historical Places, the lattice tower near Adams Street Substation will remain standing, although as a monument, not a functioning transmission tower.
Are there other components to the project?
Yes. There are upgrades that affect how the circuit breakers work for the transmission lines that connect three large substations.
What will happen to the Cushman Substation?
In the fall of 2016, some of the substation’s features were turned off, but it’s still an energized substation. In the fall of 2018, it will be disconnected from the electrical system and no longer an energized substation. Tacoma Power has not yet determined whether it will keep the building or place it on a surplus property list. Currently the building is used for maintenance of equipment and the storage of unique materials and devices.
What is the status of the nomination of some of the Cushman and Adams substation property to the Tacoma Register of Historic Places affect the project?
The Landmarks Preservation Commission recommends these be added to the register:
- The exteriors of both substation buildings
- The interior of the “condenser room” of the Cushman Substation
- The sites surrounding both buildings (not including the non-historic electrical switchyard equipment)
- The transmission tower adjacent to the Adams Substation (serving as a remnant of the original transmission line, not a functioning part of the system)
City of Tacoma staff concurs with the recommendation of the Landmarks Commission, with the exception of the interior condenser room in the Cushman Substation, which is recommended to be removed from the designation.
The nomination will be presented to the Tacoma City Council on date to be determined.
Will the historical nomination affect the pole replacement project?
The pole replacement is affected only in that, if the City Council approves keeping the single transmission tower near the Adams Substation in place and adding it to the register, Tacoma Power will need to develop a new construction plan to avoid the tower.
What is the history of the towers?
The towers are part of the Potlatch Transmission Line, which was originally built in 1925 to bring power from the Cushman Hydroelectric Project to Tacoma. Other than a few structures at the hydroelectric project, the lines on North 21st will be among the last of the original transmission line structures to be replaced. Tacoma Power replaced the Narrows lines in 2006 and North Bay lines in 2014; the Henderson Bay towers at Purdy will be replaced in 2018.
What is the project cost?
The estimated project cost is $8 million.
Why are the lines going overhead instead of underground?
Transmission lines are not typically placed underground because of the significant increase in cost. In this case, the cost would be five to 10 times more than overhead lines.
For more information, contact Nora Doyle at (253) 502-8117 or email@example.com.