Utility arborist companies heavily rely on vegetation management programs to keep power lines clear of tree-related hazards and ensure their services are reliable long-term. However, simply chopping down woody plants is not always the most socially responsible approach.
Over the past decade, environmental stewardship and sustainability have become key concerns in the arboriculture industry, leading many tree-care businesses to reevaluate their practices. Traditionally, utility vegetation management has been focused on ensuring safety, reliability and legal compliance, according to the Utility Arborist Association, but growing public interest in ecosystem conservation is changing the way arborists deal with trees, brush and other plants.
Tree Pruning: Maximizing Environmental Stewardship
Although there are many cases when cutting down a tree is unavoidable, the UAA believes that proper pruning is the best approach to vegetation management near utility lines. Pruning is not only beneficial for a tree’s overall health, but also accomplishes utility companies’ goals while minimizing harm to the surrounding environment. This can make managing deciduous trees a bit more tedious, as they tend to quickly regrow after being pruned. While tree-care professionals may end up working on the same trees as they re-encroach on power lines, the long-term impact of pruning outweighs the more direct approach of cutting them down.
To help establish a consensus about pruning best practices, the Tree Care Industry Association developed a series of voluntary standards that many tree businesses and utility companies adhere to. The ANSI 300 national pruning standards offer a wide array of recommendations for managing risk and maximizing tree health for right-of-way workers. Rather than simply chopping down encroaching trees and branches, the TCIA believes that thoughtful pruning promotes desirable branch spacing that will reduce future interference. Some of the goals of these national standards include:
- Improving branch and trunk architecture
- Discouraging tree growth in particular directions
- Restoring plants that have been damaged
- Ensuring safe and reliable utility services
Knowing when to prune, and how much, is nevertheless a case-by-case consideration. The UAA suggests that the length of time between prunings depends on the amount of clearance obtained and the rate of tree growth. As such, utility arborists should have a firm understanding of the species and size of the trees they work on, along with local worksite and weather conditions.
Brush Maintenance: An Integrated Approach to Vegetation Management
While trees are often the primary concern in residential areas, utility arborists working in electric transmission and pipeline corridors must deal with a more diverse range of vegetation. Rather than focusing on individual plants, tree-care professionals seek to convert vegetation into a more sustainable ecosystem. This is especially crucial along high-voltage transmission lines, as electricity can arc from transformers to tall trees, according to the UAA. That means areas dominated by tall-growing vegetation are a major concern for utility companies.
Much like with tree pruning, the TCIA has developed a national standard (ANSI A300 Part 7) for managing plant communities that emphasizes integrated vegetation management (IVM) strategies. Under this framework, utility managers start by setting clear objectives, such as increasing line clearance or controlling invasive plant species. Next, they must identify compatible and incompatible vegetation to help create a more holistic management plan, and select the most appropriate control methods. According to the Environmental Protection Agency, IVM practices can help reduce the need for pesticides, promote healthier ecosystems and provide greater species diversity along right-of-way corridors. By promoting the growth of lush shrub or grassy areas, utility arborists can prevent interference with overhead power lines, reduce fire hazards and improve access to remote infrastructure.
Another common approach is the use of a wire-border zone strategy, according to the North American Electric Reliability Corporation. The “wire zone” refers to right-of-way areas that are directly below power lines, where low-growing plants, shrubs and grasses (under 3 feet) can be allowed to flourish. The “border zone” constitutes the rest of the right-of-way, which can accommodate the growth of small trees and tall shrubs (under 25 feet at full maturity). By optimizing the plant communities in these areas, utility arborists are able to reduce long-term maintenance while also promoting healthy forest ecology and environmental stewardship.