The Knight Ostrander line, in the Longview, Washington district, shows the vegetation management path through the forest. Clearing “danger trees” protects the transmission line and prevents power outages.
Some of the nation’s most menacing unplanned power outages were not caused by storms or wildfires. They were caused by vegetation – brush or trees – getting too close to power lines and taking them out of service, leading to widespread, cascading outages. ome of the nation’s most menacing unplanned power outages were not caused by storms or wildfires. They were caused by vegetation – brush or trees – getting too close to power lines and taking them out of service, leading to widespread, cascading outages.
How does the Bonneville Power Administration keep vegetation from getting too close to its power lines and causing outages? It relies on a cohesive group of experts who manage the vegetation on and around the agency’s 8,500 miles of rights-of-way and facilities, such as substations, switchyards and microwave/radio sites in the Pacific Northwest.
BPA has 10 natural resource specialists that manage their respective maintenance districts. This involves identifying vegetation, such as tall trees or bushes, within a right-of-way that could cause damage, and keeping towers and structures clear of vegetation. The natural resource specialists also target “danger trees,” which are trees outside of the agency’s rights-of-way that are damaged, dead or dying that could potentially fall and damage BPA’s transmission equipment or facilities, or otherwise interfere with grid reliability.
The vegetation management team has three foresters who identify trees that need to be removed in order to provide adequate clearance when rebuilding or upgrading a transmission line. They use LiDAR, a helicopter-mounted, laser-based survey tool, to identify trees that are close to or already violating safe clearance standards. Essentially, if it’s green and grows, the vegetation management team is involved.
“We’re not just removing vegetation,” says Chris Morse, supervisory natural resource specialist. “Our team typically seeds about 20 acres a year, or partner with other entities to plant when that makes sense. We look for non-invasive, native and pollinator-friendly seeds to plant.”
Always keeping the bigger picture in mind, one of the team’s main functions is to ensure vegetation-caused outages are prevented in an economical and environmentally responsible way. This is done through implementation of long-term contracts and elimination of any redundancies in the program.
“We accomplish this through the implementation of our preventative maintenance program, allowing us to sustain low-growing plant communities at a low cost,” says Morse.
One of the team’s biggest challenges is setting priorities to accomplish its annual scope of work within its budget. Part of this balancing act requires prioritizing immediate, time-sensitive responses to vegetation threats, long-term management of the agency’s rights-of-way on a cyclical basis, and executing the work within the restrictions from environmental timing and wildfire concerns. Given the specific timelines for scoping and completing this work, there is little room for error and a lot at stake.