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.
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 during the second half of 2018.
How will the Cushman and Adams substations being placed on the Tacoma Register of Historic Places affect the project?
In June, the Tacoma Tacoma City Council determined that these portions of the property be added to the register:
- The exteriors of both substation buildings
- The sites surrounding both buildings (not including the non-historic electrical switchyard equipment)
The Council also determined that the City of Tacoma and Tacoma Power will establish a process to encourage timely redevelopment of the two properties.
What is the tentative pole replacement project schedule?
- Design and permitting: Ongoing through 2017
- Construction: April 2018 through the fall of 2018
- Cushman Substation is still an energized, functioning component of the utility’s power system. The equipment and structures within Cushman Substation fence are scheduled to be removed by 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.
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?
Currently, the building is energized, used for heavy equipment repair and storage of unique materials. In the second half of 2018, it will be disconnected from the electrical system and no longer an energized substation. Tacoma Public Utilities is committed to working with the Public Utility Board and City Council to determine an acceptable, cost-effective future use for the substations and surrounding properties.
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.