Trees and Vegetation Continue to be One of the Leading Causes of Outages for the majority of electric utilities. As a result of catastrophic storms and the Northeast blackout, utility vegetation management programs have been under increased scrutiny over the last few years.

To alleviate these problems, North America spends billions of dollars on line clearance. In addition, utility arborists have taken a proactive and instrumental role in the industry. And the ANSI A300 committee has developed standards for utility line clearance pruning and integrated vegetation management (IVM). Along with these standards, the International Society of Arboriculture, with the assistance of utility line clearance industry leaders, has developed best management practices.

STANDARDS AND BEST MANAGEMENT PRACTICES

The standards are considered to be the “what” and the best management practices are the “how to.” ANSI A300 Part 1 is the standard the arboricultural profession uses to write contract specification for pruning, and within that standard is a section on utility pruning.

When writing contract specifications, vegetation managers must consider species growth characteristics, location of the trees in relation to the line, and line construction and voltage. Vegetation managers can use best management practices for utility pruning when training employees, working with contractors or when talking with homeowners about appropriate utility pruning practices.

INTEGRATED VEGETATION MANAGEMENT

At the same time that the Federal Energy Regulatory Commission (FERC) standard FAC-003-1 was being developed, the ANSI A300 committee was developing ANSI A300 Part 7: Tree, Shrub and Other Woody Plant Maintenance — Standard Practices for Integrated Vegetation Management and Electric Utility Rights of Way. Like A300 Part 1, this standard assists vegetation managers in drafting contract specification for IVM on electric utility rights of way.

The best management practices for IVM offer a systematic approach to planning and implementing a vegetation management program that exceeds FAC-003-1. It is applicable to distribution and transmission projects and consists of six steps.

  1. Set the objective

    The overriding focus for the objectives should be on environmentally sound, cost-effective control of species that potentially conflict with the electric facility while promoting compatible, early successional, sustainable plant communities.

  2. Evaluate the site

    Vegetation managers often use site evaluations to assess field conditions for planning purposes, establish or modify objectives, set budgets, and determine human and equipment resource requirements.

  3. Define action thresholds

    The action thresholds are vegetation height and density targets that trigger specific control methods. A qualified vegetation manager should set the thresholds, which will vary from utility to utility and project to project.

  4. Select control methods

    Managers can achieve objectives through control methods such as manual, mechanical and herbicides to biological and cultural processes.

  5. Implement IVM

    Vegetation management professionals must implement minimum clearance distances (FAC-003-1).

  6. Monitor treatment and quality assurance

    Utility vegetation management programs should have system processes in place for documenting and verifying that vegetation management work is completed to specifications. Post-control reviews can be comprehensive or based on a statistically representative sample.

SIGNIFICANCE TO THE UTILITIES

Recent catastrophic events, such as storms, fires and the Northeast blackout, have led to an increased amount of interest on the part of the FERC, as well as the state utility commissions to review utility vegetation management programs.

The Utility Arborist Association is educating policy makers on the importance of sound, scientifically based vegetation management practices that are environmentally sensitive and cost effective for the utility. The ANSI A300 standards and the accompanying best management practices achieve those objectives. State utility commissions are also discussing the ANSI standards when analyzing vegetation management programs. FERC also has recognized the standards by referring to them in A300 Part 1 and Part 7.

Through a focus on standards, the utility industry is working to curb outages and improve the efficiency and cost-effectiveness of vegetation management programs nationwide.


Derek Vannice (dvannice@isa-arbor.com) is the executive director for the Utility Arborist Association and the director of certification for the International Society of Arboriculture. He joined the UAA and ISA in 1992. Vannice earned his bachelor's degree in forest management from Purdue University and a master's degree in business administration from Ball State University.