General:

Electric Transmission Maintenance's policy on vegetation management in transmission corridors is as follows:

The primary objectives of the vegetation management program are as follows:

Maintain maximum clearance between conductors and vegetation.
Remove hazard trees that could fall into lines.
Maintain fire breaks around structures that support air switches or split-bolt    
      connectors.
Remove vegetation on rights-of-way and access routes to allow adequate inspection 
      of facilities and emergency response.

MAINTAIN MAXIMUM CLEARANCE

Removal Policy
Safety, service reliability, and cost effectiveness are best achieved when trees are removed, rather than pruned. Therefore, the vegetation management policy of Electric Transmission Maintenance is focused on tree removal. When trees are removed, herbicide should be applied to cut stumps of trees that are likely to resprout whenever permission to apply herbicides can be obtained.

Pruning Option
When trees are not removed, the maximum amount of clearance should be obtained by pruning. The goal is to prune an amount that will maintain the required clearances for at least three to four years, but the minimum final clearances obtained after pruning should be as follows:

While obtaining these minimum final clearances, consideration should be given to maximum conductor sag and sway, as well as anticipated tree regrowth. In addition, no branches overhanging conductors should be left on pruned trees.

Under no circumstances will clearance be less than what is safe and  keeps PG&E in compliance with regulatory requirements (see Exhibit). Techniques of modem arboriculture should be used when pruning to direct regrowth away from power lines and minimize adverse effects to tree health.

REMOVE HAZARD TREES
Hazard trees, whether on or off right-of-way, should promptly be removed.

The California Forest Practice Rules define a hazard tree (or danger tree) as "any tree located on or adjacent to a utility right-of-way or facility that could damage utility facilities should it fall where 1 ) the tree leans toward the right-of-way or 2) the tree is defective because of any cause, such as heart rot, shallow roots, excavation, bad crotch, dead or with dead top, deformity, cracks or splits, or any other reason that could result in the tree or a main lateral of the tree falling."

Extreme conditions, such as snow loading, high wind velocities, and  saturated soils, should be assumed when evaluating trees for  potential hazards

MAINTAIN FIRE BREAKS
During the fire season, flammable fuels must be kept clear at least  ten feet in each direction from the outer circumference of transmission structures supporting split-bolt connectors or air switches as detailed in the Power Line Fire Prevention Field Guide.

REMOVE VEGETATION FOR INSPECTION AND ACCESS
Vegetation management is necessary for operational considerations, including inspection of structures, vehicular access, structure-to-structure line of site for ground inspections, and fuel load reductions on right-of-way.

Inspection of structures - brush and trees should be 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 should be kept clear of interfering vegetation.

Structure-to-structure line of site - brush and trees should be removed to allow visual inspection from the ground of conductors and structures one span in either direction.

Fuel load reductions - In critical situations, heavy vegetation should be removed from the right-of-way if damage to facilities is possible from wildfires.

The need for vegetation management is primarily determined during inspections by transmission troublemen. Inspection frequencies for lines are established by each transmission line supervisor based on considerations of line criticality and line condition. Line sections are prioritized for more frequent routine inspections than the whole line if vegetation conditions warrant more frequent inspections. In addition, specific follow-up inspections can be triggered by vegetation proximity or fast-growth concerns observed during routine ground or aerial inspections. Troublemen document vegetation conditions in the overhead line inspection database.

PG&E's Land Rights
Vegetation should be managed to the fullest extent allowed by PG&E’s land rights: Trees should be removed whenever PG&E has the right.

Land rights documents should be reviewed to ascertain land rights for any specific parcel when there is doubt about land rights. Normally, a PG&E land agent should be consulted to locate and interpret land rights.

Notification and Permission
Prior to entering upon private or public property to perform vegetation management, the owner should be given adequate notice of the work contemplated. Advance notification provides property owners adequate time to raise any concerns they may have.

Permission must be obtained (preferably in writing) to remove trees when PG&E land rights do not include the right to remove trees. Also, except for PG&E-owned property, permission must be obtained to apply herbicides.

In order to assess the effectiveness of Electric Transmission Maintenance’s vegetation management program and evaluate service reliability, transmission line supervisors should ensure that the circumstances of all known tree related outages are documented. The following categories of information should be considered when evaluating tree-related outages:

Location where tree problem occurred

* line and span
*  if tree failure, was tree off right-of-way

* tree failure: where a tree uproots, breaks at the trunk, or loses a branch
* tree-line contact: where a tree grows so close to the line that a fault occurs  
    or where a line sags or sways so close to the tree that a fault occurs
* 3rd-party error: where a 3rd party, such as a logger or PG&E contractor, 
    causes a tree to hit the line.

* winds, saturated soils, tree health, snow loading, etc.

* oak, pine, eucalyptus, etc.

Richard M. Cashdollar
Director, ETM M&C Support
CLFilmer (8-223-3678)

Detailed Procedures/Attachment/Exhibit:

Basic Fire Prevention Regulations

*        California Public Resources Code

Section 4292 -- During the fire season, flammable fuels must be kept clear at least ten feet in each direction from the outer circumference of transmission structures supporting split-bolt connectors or air switches.

Section 4293 -- Minimum radial clearance between conductors and vegetation required during fire season:

        60/70 kv . . . . . . . . . .  4 feet
        115/230/500 kv. . . . .10 feet

Rule 35 (Tree Trimming) -- Minimum clearance between conductors and vegetation required at all times:

        60/70 kv . . . . . . . . .1.5 feet
        115 kv. . . . . . . . . . .1.6 feet
        230 kv. . . . . . . . . . .2.6 feet
        500 kv . . . . . . . . . .10.0 feet