- What is the accelerated pole replacement program?
- What is the pole inspection process?
- How does City Light prioritize poles for replacement?
- How many poles will City Light replace during this accelerated program? When will this work be completed?
- Why is City Light using taller poles?
- What are steel stays and pole trusses? How do they help the utility poles?
- What are double poles? What is City Light doing to address double poles?
- I noticed a double pole that looked unusual. Is this normal practice?
- Where can I find additional information about the pole replacement program?
Seattle City Light is replacing aging utility poles throughout the utility’s service area to improve and upgrade electrical reliability. During this work, electrical wires and equipment will be replaced and relocated to the newly installed poles.
The new poles will be placed alongside pre-existing poles. They will meet standard heights and widths required for overhead power line construction. This may mean that poles in your area will be slightly taller and approximately two inches wider than existing poles.
This work is part of a larger effort to accelerate and better prioritize pole replacements throughout the utility’s service area. Recommendations were made to improve this process based on the East Marginal Way storm incident in April 2019.
The accelerated pole replacement program is overseen by a project manager that coordinates the pole replacement work with an emphasis on safety. Poles with the least strength will be prioritized during this work. City Light has also reprioritized existing staff resources and used emergency contracting processes to hire vendors and accelerate pole replacements.
City Light maintains approximately 91,000 wooden poles in its service territory. The utility’s “Inspection Procedures for Wood Pole Assessment” were developed in conjunction with a third-party vendor and are carried out by another third-party vendor. The inspection process includes a visual, sound and bore partial excavation inspection as demonstrated in this 2017 Seattle Channel video and described in this 2014 blog post.
In 2008, City Council requested that City Light implement an asset management program. To establish a baseline, over 2009-2010 all wooden utility poles were inspected visually and using a basic hammer sounding technique. This technique involves hitting a pole with a hammer; a healthy pole should produce a solid-wood sound while a pole with internal decay will produce a hollow sound. From 2011 on, we began inspecting approximately 10% of our wooden utility poles per year using more thorough boring inspection and subsurface excavation methods. Seattle City Light has been on a steady-state program cycle to reinspect and test 10% of our poles per year. Depending on testing results, poles will be treated or replaced as appropriate. With this strategy we will visit all poles once every 10 years.
Pole longevity can vary widely based on the wood species, treatment and the environment where it is placed. A typical modern pole should last 40-60 years. City Light does have some poles much older than that; older poles were often made from old growth timber and subject to preservation methods that extended the useful life much more than modern treatments.
As part of the development of the asset management program in 2008, City Light hired a consultant to develop a classification system for rating poles. This classification system was updated in 2011 (table below). Each pole inspected is assigned a priority rating from 1 to 5; poles identified as P1 or P2 are flagged for replacement.
|Priority Rating||Maintenance Required||Action Needed|
|P1||Replace||Pole will need to be replaced|
|P2||Replace||Pole will need to be replaced|
|P3||Reinforce||Pole will be assessed for reinforcement (through steel stays and/or pole trusses)|
|P4||None||Pole is serviceable, no action needed|
|P5||None||Best pole condition, no action needed|
Depending on the availability of funding and resources, we are looking to replace 1,400-2,000 poles annually over the next five years, at which point any newly identified weakened poles would be addressed in our regular annual program.
- Taller poles are needed to meet safety requirements for higher voltage electricity.
- Proper clearances are required between power lines so that crews can work safely and efficiently when performing repairs.
- Minimum clearances from the communication lines of other utilities are required.
- Taller poles provide minimum height clearances for service lines to individual homes.
Poles that do not require replacement may be reinforced by trussing or installing steel stays. These methods extend the life of poles at the higher end of remaining strength. This is cheaper and faster than replacement.
Double poles exist when a new utility pole is installed next to a pre-existing pole that is scheduled for removal. When new utility poles are installed, City Light transfers their equipment and wires onto the new pole. Other communication utilities may also have equipment on the pre-existing pole that will need to be transferred to the new pole before the old pole can be removed. This could take several months to complete.
Seattle City Light is working with CenturyLink and other communication companies to expedite the pole removal process. We will continue to monitor and coordinate these efforts as needed to facilitate the removal of old poles.
Some poles may be anchored or tied to the pre-existing pole to secure it until the utility and communications companies have transferred their equipment. This is normal practice and common among utilities.