By Ann Thelen
In Iowa, beautiful trees and vegetation dot the rolling hills of the landscape. We also have ever-changing seasons, which bring sunny skies, windy days, thunderstorms, ice storms and an array of weather patterns. During a strong thunderstorm, trees whip around and branches crack. It can be Mother Nature’s angry way of pruning trees.
Trees and plants provide many benefits, but poorly placed trees can lead to big problems. Fallen limbs, branches and trees are a top cause of power outages in Iowa. When this happens, electric power restoration can be timely, costly and inconvenient for electric cooperative members. A proactive and strategic approach to keeping trees away from power is vital to providing you with safe and reliable electric service.
Why tree trimming is necessary
In 2003, the Northeast U.S. suffered a power outage that was the second most widespread electrical power outage in U.S. history. More than 10 million people in Canada and 45 million people in the U.S. were affected. The blackout was caused when high-voltage power lines came in contact with overgrown trees. The cascading effect forced the shutdown of more than 100 power plants. It only took nine seconds for the grid to collapse. Federal regulations for vegetation management by power providers soon followed to prevent a similar situation from happening again.
“In northeast Iowa, we are blessed with a lot of trees. Proper vegetation management has always been an important priority for our cooperative members,” says Paul Foxwell, executive vice president/general manager at Allamakee-Clayton Electric Cooperative, Inc. (ACEC). ACEC provides electric power to more than 9,900 members on 2,508 miles of line throughout eight counties.
Vegetation management is a preventative process to keep trees and brush from coming into contact with power lines. The area – typically 25 feet in each direction of the power line – is known as the utility right of way. This process is important for electric service reliability and more importantly for safety. If a child is climbing a tree with branches that are in contact with energized power lines, it could be fatal for the child. When a limb brings down a power line in a storm, the line remains energized and dangerous until the cooperative can safely de-energize it.
In the early 1990s, ACEC commissioned a study to put a structure behind their vegetation management program. With roughly 40 percent of the co-op’s outages caused by trees, it was a wise investment.
“The study was extremely helpful in identifying how often we needed to be cutting, trimming or spraying vegetation,” Foxwell says. “We work hard to adhere to what we learned in the study and spend approximately $750,000 per year on vegetation management. It’s a significant amount of money going toward maintenance, but it’s essential.”
Based on the study, ACEC learned that woody vegetation increases in biomass at a rate of 14 percent per year. While that may not be significant on a twig, the exponential growth on a 10- or 20-foot tree can create big problems.
Like all electric cooperatives in Iowa, ACEC is on a well-prescribed cycle of managing the vegetation process on annual rotations.
“We are on a 7- to 10-year rotation of trimming and cutting in certain years and using mid-rotation herbicide applications – either just on the base of the tree or careful foliar applications,” Foxwell explains. “If you don’t stay on top of it, your costs go up because it becomes that much more difficult to manage as the vegetation becomes larger and larger.”
To maintain 2,500 miles of line, two certified arborists are on staff – and shared with nearby MiEnergy Cooperative and Heartland Power Cooperative – to manage the program and ensure adherence to state and federal guidelines.
Contractors are used for the work out in the service territory and are well-trained and skilled in their roles. They are all certified applicators – meaning they have undergone specific training to properly apply any type of herbicide that is used to control vegetation. Sprays are carefully designed to only kill woody growth, for example, while keeping grass and other non-troublesome plants alive. Herbicide applications are much more cost-effective than going in and trying to clear everything with chainsaws and mechanical tools.
“We are creating rights of way restoration by developing habitat-friendly environments with grasses and low-growing brush,” Foxwell says.
For members who may be concerned about spraying – perhaps they have an organic farming operation – ACEC is mindful of the members’ wishes.
Safety and reliability are paramount
In southern Iowa, Access Energy Cooperative and Chariton Valley Electric Cooperative, Inc. take similar approaches to vegetation management.
Kevin Wheeler, general manager/CEO, Access Energy Cooperative, says their top priorities are safety – first and foremost – and reliability.
“We are proactive because we don’t ever want someone hurt due to a vegetation problem,” he says. “When you have a robust plan, your outages will decrease significantly. In November, we had an early winter storm and our vegetation management process made a huge difference. Where there were blinking lights, it was in areas we hadn’t trimmed yet as part of our 5-year cycle.”
In its 10-county southeast Iowa service territory, Access Energy Cooperative has 2,200 miles of lines, which means 430 miles are managed each year.
“We work to maintain a 20-foot clear zone on each side of the power lines,” Wheeler says.
“Trimming is a necessity of having safe, reliable power.”
Bryon Stilley, general manager of Chariton Valley Electric Cooperative, Inc., which serves seven counties in southern Iowa, emphasizes the member benefits of being proactive with vegetation management.
“Safety is the main reason we have a robust program in place; however, it’s also made a big difference in system reliability,” Stilley says. “When I came to Chariton Valley Electric Cooperative 11 years ago, we would have line crews working all night from a storm that had 20 mph winds.”
Across the co-ops, member education and notification of vegetation management plans are communicated through newsletter articles, bill stuffers, door hangers and even personal visits by the staff or crews who are performing the work.
“We try to go above and beyond to make sure our members are well-informed and satisfied,” Stilley says. “If a member doesn’t want a tree trimmed or removed and we need to do it, we give them a selection of new trees to pick from. These trees are ones that will grow within a safe distance, and we’ll plant one or two at no charge.”
Contact your local electric cooperative if you have questions about proper vegetation management or where to plant trees. If you have a tree or other vegetation that is in contact with a power line, never attempt to prune it yourself. Contact your electric cooperative for assistance.
Ann Thelen is the editor of Living with Energy in Iowa.