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Puget Sound Energy reliability project

Duvall enhanced tree trimming project

Summer 2013 project complete
  • Tree work began in February 2013 and was completed in early June 2013.
Project overview
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Project Map

Many customers in Duvall are served by a 28-mile-long power line. In the past, the line’s length, coupled with its proximity to dense forested areas, put it at risk for tree-related power outages. Between 2008 and 2012, customers served by this power line experienced 68 power outages related to trees or branches coming into contact with the line.

In an effort to decrease tree-related power outages our customers in the Duvall area experience, PSE routinely conducts maintenance pruning and hazard tree removal along the entire 28-mile-long power line. In addition to the maintenance work, PSE implemented an enhanced tree trimming technique along 15 miles of the line between February and June 2013. While regular tree maintenance focuses primarily on pruning trees that grow under or into power lines, the enhanced pruning technique involved removing all overhanging branches above the lines, sometimes called “lines to sky” pruning (see graphic of “normal” versus “enhanced” tree pruning and "before and after" image). We believe that by applying the enhanced pruning technique along with regular maintenance customers may see a reduction in power outages caused by limbs and branches falling into the lines.

The enhanced tree trimming technique was developed based on the results of an independent study of PSE’s vegetation management system and is monitored by certified arborists. The enhanced pruning focused on certain tree species along the routes that have a tendency for branch failure, including Douglas Firs, Big Leaf Maples, Black Cottonwoods and Red Alders.

The areas PSE targeted for the enhanced tree pruning method included:

  • Kelly Rd from NE Big Rock Road to Stossel Creek Rd
  • NE Lake Joy Rd from Kelly Rd to 342nd Ave NE
  • NE Big Rock Rd from Kelly Rd heading NW to Odell Rd / Odell Rd to NE 139th St
  • Big Rock Rd from Odell Rd NE to Batten Rd / Batten Rd NE to approx.14340 Batten Rd NE
  • Big Rock Rod from Batten Rd west to 275th Ave NE / 275th Ave NE to the Duvall substation at 14401 278th Ave NE

(See project map for locations.) 


Videos on Tree Trimming

Play these videos explaining the importance of tree pruning to minimize tree-related power outages for our customers, and describing the difference between PSE's normal and enhanced tree pruning practices.

Want to know more?

If you have any questions about PSE's vegetation management process or policies please call 1-888-225-5773 or visit our vegetation management section on

Download information

Pruning examples: Before and after image
Project notice, January 2013
Frequently Asked Questions
Project map
Project timeline map (Revised April 2013)
Normal versus enhanced tree pruning graphic - Conifer
Normal versus enhanced tree pruning graphic - Deciduous