Tree-trimming Standards and Practices City Council Work Session November 19, 2007
Dec 16, 2015
Tree-trimming Standards and Practices
City Council Work Session
November 19, 2007
Introduction• Two General Categories
- Transmission - Distribution
• Work Performed by Outside Contractor - ANSI A300 (Tree Care Operations – Tree, Shrub, and other Woody Plant Maintenance – Standard Practices)- Interpretation and Implementation of A300- Line clearances to GP&L standards
• Line Clearances - Transmission Standard (GP&L OH-907)- Distribution Standard (GP&L OH-908)
Transmission Standards Overview
• Subject to NERC Standard FAC-003-1
• Lists ANSI A300 as industry “best practice” for vegetation management
• Transmission Vegetation Management Program (TVMP) per FAC-003-1
• Passed ERCOT/NERC audit this year
• Liable for ALL vegetation related outages
• Increased penalties under nodal market
GP&L Standard OH-907
Typical Transmission Standard
• Zones defined by the TVMP
- Border zone requires documented plan
- Wire zone requires immediate resolution
New Transmission Design
• New transmission design increases clearances
Transmission Standards Outlook
• Development along transmission corridors - Increase compliance effort- Increase in vegetation encroachments- Increase interaction with property owners
• Reduce this impact by providing information to property owners along transmission corridors.
• Improve corridor access to insure timely identification of potential encroachments.
Distribution Standards Overview
• Majority of annual trimming operations• Not currently subject to regulatory audits• Line clearances per GP&L OH-908• Contractor adheres to ANSI A300 for
vegetation management• Trimming format (V-out, side, notch, etc.)
chosen to provide desired clearances without killing tree.
• Trunk location typically dictates trim format
GP&L Standard OH-908
Distribution Standards
V-Out Format
Distribution Standards
Side Format
Distribution Standards
Notch Format
Distribution Standards Outlook• NERC regulatory voltage will continue to be
lowered – distribution may be subject to standards in the near future?
• Increased trimming in past 3-5 years – greatly reduced storm related outages
• System reliability directly affected by magnitude of trimming operation
• Enhance customer notification process• Provide information on clearance
requirements to property owners
QUESTIONS?
Balancing aesthetics & reliability!