The Environment> Vegetation Management Policy

Introduction
Platte River Power Authority continually manages vegetation in and near its transmission right-of-ways to maintain safety and electric reliability.

Fallen trees and branches are a primary cause of electric power outages; therefore, vegetation must be kept clear of electric power lines. Additionally, consideration must be given to vegetation on right-of-ways that would affect the safety and effectiveness of structure inspections, vehicular access, structure-to-structure line-of-sight and any vegetation that poses a potential fire hazard.

Objectives
The primary objectives of vegetation management are:

• To minimize the risk of trees or branches falling into transmission lines causing electric service outages.
• To maximize the safety of all people who, for any reason, need to be in the vicinity of Platte River’s transmission lines.
• To maintain sufficient clearance on right-of-ways and access routs to allow for adequate inspection of facilities and emergency response.
• To meet all federal regulatory guidelines for vegetation management.

Management Zones
Platte River acknowledges two zones in managing vegetation near high voltage power lines. The first zone is directly beneath the transmission wires and is called the “wire zone.” The wire zone has a vegetation height maximum of 15 feet. Any vegetation in the wire zone above this height will be removed.

The next zone outward from the wire zone is the “border zone” where trees are managed on a 45-degree rule. Starting at a height of 15 feet, where the wire zone ends, trees in the border zone will be pruned at a 45-degree angle away from the wire zone. This type of management will prevent trees from falling into and contacting transmission lines. Click to see a diagram of the wire and border zones.

Inspection and Access Requirements
Platte River requires that access to its right-of-ways and facilities provide for safe and effective inspection of the facilities. To assure safety and effectiveness, the following guidelines are followed:

• Inspection of Structures - brush and trees will be completely removed at least ten feet in each direction from the outer circumference of transmission structures and down guys.
• Vehicular Access - access lanes of at least ten to twelve feet in width will be kept clear of interfering vegetation.
• Structure-to-Structure Line-of-Sight - brush and trees will be removed to allow visual inspection from the ground of conductors and structures one span in either direction.
• Fire Danger - In critical areas, heavy vegetation will be removed from the right-of-way if damage to facilities is possible from wildfires.

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Inspection Frequency
The need for vegetation management is primarily determined during inspections by Platte River personnel. Full inspections will occur bi-annually in the spring and fall. Follow-up inspections can be triggered by vegetation proximity to facilities or fast-growing vegetation.

Tree Removal and Pruning
Any vegetation found to be in violation of clearances during inspections will be pruned or removed.

Whenever possible, adequate clearance around facilities will be obtained by pruning. The goal of pruning is to trim an amount that will maintain the required clearances for, at least, three to four years.

When pruning is not adequate or when trees are deemed a high risk to electrical service or to the safety of the general public, they will be removed by Platte River. High-risk trees, called “hazard trees”, are specifically defined by Platte River as any tree located on, or adjacent to, a transmission line right-of-way or substation that could damage the facilities should it fall. Such trees generally, but not always, lean toward the right-of-way or are defective. A number of things can cause a tree to be defective such as heart rot, shallow roots, death of all, or part, of the tree, deformities, cracks or splits, or anything that could result in the tree or a main branch of the tree falling.

Extreme conditions such as snow loading, high winds and saturated soils will be assumed when evaluating trees for potential hazards.

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Landowner Notification and Permission
Landowners are given advance notice of anticipated tasks to be performed on a right-of-way. This provides property owners time to raise any concerns they may have.

Preventative Approach
Platte River prefers to take a preventative approach to vegetation management rather than a reactive approach and recommends that any new trees planted on, or near, transmission right-of-ways have mature heights that comply with the height requirements as mentioned before.

Planting according to mature height will reduce the likelihood that trees will eventually need to be pruned or removed.

For a guide to trees and their mature heights, go to Colorado State University’s Cooperative Extension Web site: www.ext.colostate.edu/ptlk/1715.html.

Contact trees@prpa.org with any questions.

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