Contracted crews work to keep branches off utility wires
The utility company has a handful of two-man crews working on any given day to protect the island’s five electrical circuits from outages caused by vegetation overgrowth. The work began in March and should finish next month. National Grid employs six contractors to do the work in Rhode Island, but all of the Jamestown crews are from Davey Tree.
About 20 percent of outages are caused by vegetation interference, said spokesperson David Graves. Other causes include animals chewing on wires, cars running into utility poles, and even Mylar balloons getting stuck.
National Grid conducts two tree-related programs. The first is the pruning program. Once every four years, crews are sent into town to prune trees around the power lines and prevent interference from growing tree limbs. Branches that grow into power lines have the potential to cause a shortage, which can result in an outage. Tree limbs that fall can also cause the lines, or the poles themselves, to come down.
The other program is the removal of hazardous trees. National Grid will identify diseased or dying trees that might come down on power lines if a dead tree topples. The utility company works with towns and property owners to remove the trees without cost. The removal program has been underway in Rhode Island for five years, and was conducted earlier this year in Jamestown.
“Along certain circuits we can identify where in our system there have been a number of outages caused by vegetation interference,” said Graves. “We take a look at those trees that are in proximity to our lines that present a threat to the reliability of our system.”
According to Graves, National Grid learned a lesson from Hurricane Irene in 2011. About 60 percent of the outages that were caused by vegetation interference were caused by tree failure, and merely pruning the trees would not have prevented the outages.
“The trees get bigger and more mature, and the branches extend,” Graves said. “The chances of failure increase as they grow.”
Chris Rooney, forestry supervisor for National Grid, conducts both operations throughout the state. When he speaks to towns about hazardous tree removal, there is always a discussion about whether a particular tree is an asset or a liability.
“You might have a beautifullooking tree, but structurally there could be something wrong with it, whether there is a crack or decay that somebody who isn’t trained doesn’t know,” Rooney said. “That’s the hard part: educating people.”
National Grid only has maintenance agreements where its poles are located. Since trees are often on private property, and not covered by any agreement, the company has to get permission from the property owners.
“We have to work with people every four years, to trim or remove hazardous trees, so we want to be on the same page,” Rooney said.
According to Rooney, National Grid has been working closely with the local tree warden. Rooney also met with the tree commission prior to beginning the work. One crew goes around town leaving door cards to inform homeowners of the work that is going to be done. The company also placed an ad in the Jamestown Press to explain the scope of the work. Despite the explanation, Rooney said that the company occasionally encounters a homeowner who refuses the trimming.
“We take the time and describe to them why we should do the trimming,” Rooney said. “We won’t force the trimming on anybody. Hopefully they use their best discretion to rectify the situation.”
A property owner does have the right to refuse the trimming. In those cases, the property owner must sign a waiver so that if problems arise, and a complaint is filed with the Public Utilities Commission, National Grid can show that it made the attempt to trim the tree.
Graves said that the scope of the trimming work is determined by the number of circuits, and the work is prioritized in accordance with the town’s circuit map. The crews are charged with trimming from each substation to the last house on the circuit. Hazardous tree removal is prioritized based on the importance of the line.
After the crews have completed their work, National Grid sends out supervisors to make sure that the crews did a thorough job with proper trimming, and that they did a proper cleanup.
“We have to be back here in four years, so we want to make sure they did a nice job,” Rooney said. “Then we pay them for the project.”
Despite the fact that tree failure was responsible for outages in the north end during Hurricane Sandy, National Grid was not involved in the decision making that led to the takedown of trees along North Road near the reservoir.
National Grid has budgeted $5.2 million for tree trimming in Rhode Island this year. That amount includes approximately $650,000 for police details to work with the trimming crews.