Transmission lines are high-voltage and extra high-voltage power lines that are the backbones of the OPPD electric system. They act as a freeway for large amounts of power to flow over thousands of miles between substations in OPPD’s territory and the larger interconnected grid in the region.
OPPD’s transmission system consists of a variety of line sizes, shapes and voltages, which are vital to the reliability of our system. OPPD is responsible for ensuring that our transmission corridors are clear of trees, structures and other vegetation that would be a risk to safe and reliable operations.
Federal, regional and electric industry regulations and standards require minimum safety clearances to ensure vegetation does not come into contact with high-voltage overhead transmission lines.
If vegetation located in a transmission corridor is not compatible with the safe operation of the system, it can result in widespread electric power outages (blackouts) and/or unsafe conditions for the public. Thus, OPPD must maintain the transmission corridors and keep them clean of obstructions.
In addition to the following information, here are several frequently asked questions.
Transmission Line Sag and Sway
Power lines sag from high electric loads and ambient temperature (i.e. hot weather). Lines also sway in high winds. OPPD considers both factors when determining if trees need to be trimmed or removed.
Remember to treat all power lines with respect by keeping a safe distance away from them, and report all downed lines to OPPD at 800-554-6773.
Transmission Corridors
OPPD has a right to manage property below our transmission lines. We may trim or remove vegetation in or adjacent to the corridor in order to eliminate danger. This includes trees that could potentially fall within 15 feet of power lines.
Corridor widths depend mainly on the size of the power line and typically range from 50 to 200 feet.
Vegetation Management Program
OPPD maintains vegetation on more than 1,350 miles of metropolitan and rural transmission corridors from southeast Nebraska to northeast Nebraska.
Maintenance activities include trimming and removing trees, mowing, applying herbicide and eliminating hazardous tree/power line conditions. In addition, OPPD may inspect and require the removal of structures that have been built in the corridor without the utility's approval. These periodic maintenance activities are necessary to provide safe and reliable service to all customers within and outside of OPPD’s service territory.
Please keep in mind, the frequency of maintenance activities in transmission corridors is determined by many factors as we prudently manage resources and costs across a wide variety of OPPD projects. As part of our commitment to customers, OPPD evaluates every obstruction in the transmission corridor on a case-by-case basis to determine the best overall solution.
Tree-Trimming
Tree trimming provides for mandatory clearances between power lines and trees. Trees at the edge of the corridor are trimmed to eliminate branches growing into the easement space.
Tree-trimming may be done by crews using mechanical trimming equipment or aerial lift trucks, or by climbing crews.
Tree Removal
Transmission crews remove vegetation that threatens the safe and reliable operation of the electric transmission system.
The main purpose of OPPD's vegetation management program to remove all incompatible trees and shrubs located within the transmission corridor. Any tree that poses a potential hazard to the integrity of the transmission line is considered a danger tree and will be removed.
Mowing
OPPD contractor crews clear vegetation and redefine the corridor width with light-duty power equipment. Vegetation near structures, support wires, fences, streams or other difficult-to-access areas may be removed using manual equipment.
A combination of mowing and low-volume herbicide applications are used to manage tall growing woody vegetation. This integrated vegetation management approach helps promote and establish a stable, diverse, low-growing plant community on the right-of-way, reducing the potential for soil erosion and is beneficial for wildlife.
Guidelines for Activity in a Transmission Line Corridor
- You must obtain prior approval from an OPPD forester before planting a tree, building any structure, parking lot or other structure in a transmission line corridor. Pools are never allowed.
- Contact the OPPD Real Property and Land Management team to begin the variance approval application process.
- No trees or shrubs will be allowed to grow adjacent to line structures and support wires.
- The potential height of a tree or shrub and its planting location will determine whether it is acceptable within the corridor.
- Grasses and wildflowers are allowed within the established corridor without restriction.
- Please remember that vegetation located within or along the immediate edge of the corridor is planted at your own risk. It may be necessary to remove vegetation if it interferes with emergency restoration, line-maintenance or line-construction.
For public safety and grid reliability, it's also important to landscape carefully around padmounted transformers.