UTILITY VEGETATION MANAGEMENT 

FINAL REPORT 

MARCH 2004 

FEDERAL ENERGY REGULATORY COMMISSION 

UNITED STATES GOVERNMENT 

COMMISSIONED TO SUPPORT THE FEDERAL INVESTIGATION 

OF THE AUGUST 14, 2003 NORTHEAST BLACKOUT 

CN Utility Consulting, LLC 

Contact: Robert Novembri 

 Phone: 415.897.8883 

Email: rnovembri@cnutility.com 

 Contract: FERC-03AL-30574 
THIS REPORT WAS PREPARED BY CN UTILITY CONSULTING, LLC 

PRINCIPAL AUTHORS: 

Stephen R. Cieslewicz 

Robert R. Novembri 

CONTRIBUTING PROFESSIONALS: 

William S. Gray Jr., P.E. 

Dr. David Wood, Professor Emeritus, UC Berkeley 

EDITOR: 

Mary F. Burns 

PROJECT MANAGERS: 

Saeed Farrokhpay, FERC 

Alison Silverstein, FERC 

Gary Nakarado, FERC 

The principal authors of this report have over 50 combined years of experience in dealing with all matters 

related to UVM programs, industry practices, laws, and standards. CN Utility Consulting, LLC has 

performed industry assessments of UVM laws and regulations, and has been directly involved with the 

promulgation and development of various industry standards. Most recently, CNUC completed what is 

considered to be the largest and most comprehensive UVM benchmarking study ever completed in the 

industry. This comprehensive study included the active participation of 55 utility companies (large and 

small) in North America, and covered the full gamut of UVM-related subjects. 
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CONTENTS 

I. EXECUTIVE SUMMARY 1 

II. INTRODUCTION 5 

III. BACKGROUND 6 

 The Purpose of UVM: When Trees and Power Lines Conflict 6 

 Introduction to the UVM Industry and Programs 8 

 Transmission and Distribution (T&D) UVM Activities 8 

 Current Requirements for UVM Work 9 

 Impediments to Completing Required UVM Work – Competing Interests 15 

 The Urgency of the Work 16 

 The Influence of Individual Property Owners 18 

 Transmission Right-of-Way Maintenance 19 

 Precipitation and Tree Growth 23 

 UVM Funding and Work Management 24 

IV. FIELD INVESTIGATION 26 

 Field Reviews Related to the August 14th Outage 26 

 Fault Chronology, Observations at Field Sites and Comments 28 

V. UVM PROGRAM ASSESSMENTS 38 

 American Electric Power 40 

 FirstEnergy 46 

 Cinergy 52 

 Detailed UVM Responses 57 

VI. RECOMMENDATIONS 67 

 General Industry Recommendations 67 

 Recommendation for Oversight and Enforcement of UVM Activities 68 

VII. BEST MANAGEMENT PRACTICES 70 

 Background 70 

 Best Management Practices in the Transmission UVM Industry 70 

 Best Practices for New Transmission Facilities 71 

 Best Practices for Ongoing Transmission UVM Operations 72 

VIII. LIST OF APPENDICES 80 
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I. EXECUTIVE SUMMARY 

TREE AND POWER LINE CONFLICTS 

It is generally accepted that the single largest cause of electric power outages occurs when 

trees, or portions of trees, grow or fall into overhead power lines1

. Virtually every electric 

customer in the US and Canada has, at one time or another, experienced a sustained electric 

outage as a direct result of a tree and power line conflict. While this is a more common problem 

on distribution lines, transmission tree-related outages are also experienced on a regular basis. 

While not as visible to the public as tree related outages, tree and power line conflicts have also 

caused significant wildland fires in both the US and Canada. 

Electric utility companies actively work to mitigate these threats. In fact, Utility Vegetation 

Management (UVM) programs represent one of the largest recurring maintenance expenses for 

electric utility companies in North America2

. Utilities and regulators generally agree that keeping 

trees and vegetation from conflicting with overhead conductors is a critical and expensive 

responsibility of all utility companies concerned about electric service reliability and fire 

mitigation. 

REPORT BACKGROUND 

CN Utility Consulting, LLC (CNUC) was commissioned to perform the following tasks in support 

of the federal investigation of the August 14, 2003, Northeast Blackout: 

1. Collect and analyze information and data regarding transmission right-of-way 

vegetation management practices of three electric utility companies in order to 

assess the strengths and weaknesses of each company’s vegetation management 

program. The utilities are American Electric Power (AEP), FirstEnergy (FE), and 

Cinergy. 

2. Identify generic best practices for transmission-level vegetation management to 

enhance system performance and transmission reliability. 

3. Assist in the field investigation and prepare a written Initial Report regarding the 

August 14th vegetation-related faults on the following circuits: 

• Stuart – Atlanta (345kV) AEP 

• Star – South Canton (345kV) FirstEnergy 

• Harding – Chamberlin (345kV) FirstEnergy 

• Hanna – Juniper (345kV) FirstEnergy 

INITIAL REPORT FINDINGS 

Prior to the publication of this report, CNUC completed the Initial Report3

 required in Task 

Three. The Initial Report provides the results of the field investigations performed at AEP and 

FE. Portions of the report are included in this publication. 

 

1

 While this varies between utilities, it is generally accepted that tree related outages are one of the most significant 

threats to the delivery of electricity. 

2

 While this varies between utilities, it is generally accepted that UVM expenses are one of the largest expense items 

associated with maintaining overhead transmission and distribution electrical systems. 3

 Available at the Federal Energy Regulatory Commission Web Site: 

http://www.ferc.gov/cust-protect/moi/uvm-initial-report.pdf
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Major Finding of the Initial Report 

During our field investigation we determined that overgrown trees, as opposed to excessive 

conductor sag, were the cause of each of the faults investigated in Task Three. Further, we 

concluded that had all the trees, which contributed to the August 14th outage, been adequately 

pruned or removed prior to the event, the blackout would likely have not occurred. 

Broader Review of Preventing Tree and Power Line Conflicts 

The topic of preventing tree and power line conflicts requires a comprehensive review of various 

issues that influence UVM programs. As we discuss throughout this report, the conditions and 

influences that contributed to the August 14th tree and power line conflicts currently exist 

throughout the US and Canada. We are convinced that the conditions scrutinized in this 

investigation are not isolated or limited to the utilities involved in the August 14th Blackout. The 

conditions that led up to this event can be found in most States and Provinces throughout North 

America. 

FINAL REPORT FINDINGS 

In addition to detailing the specific findings about the August 14th Blackout, this report presents 

an overview of the UVM industry to provide a technical and industry context for understanding 

the findings. Information is provided about UVM organizations, work issues, legal and regulatory 

requirements and restraints, professional standards, and the need for improvement in electric 

industry practices and utility oversight. The findings in this report are based on our investigation, 

years of direct experience in UVM related issues, and our understanding of general industry 

practices through our recent benchmarking of UVM activities in North America4

. 

This report also satisfies the requirements of Task One by assessing the strengths and 

weaknesses of the UVM programs at AEP, FE, and Cinergy. 

Major Finding Related to Task One 

Our findings in brief are that the three utilities studied in this report generally conduct their UVM 

operations within the range of current ”average” industry standards. Given that the line to 

ground faults that precipitated the blackout have been determined to be a result of inadequate 

vegetation management practices, we believe and strongly recommend that the industry 

“average” or standard needs to be substantially improved. 

REPORT RECOMMENDATIONS 

Reducing the likelihood of future similar occurrences will require significant changes in both the 

UVM industry and, we believe, the appropriate oversight agencies. Additionally, the initial 

improvement will cost more money, though we believe that over time a more consistent and 

systematic approach will result in lower costs. This investment will also result in significantly 

improved electric service reliability for utility customers, and a reduction in emergency repair 

costs through the reduction of outages. 

This report contains many general and specific recommendations directed at a wide and diverse 

audience. We could not discuss all of these recommendations in this Executive Summary but 

offer the following table that indicates where additional specific recommendations can be found. 

 

4

 CNUC completed what is considered to be the largest and most comprehensive UVM benchmarking study ever 

completed in the industry. This comprehensive study included the active participation of 55 utility companies (large 

and small) in North America, and covered the full gamut of UVM-related subjects. The study is the property of CNUC 

and the participating utilities. 
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3⁄4 Page 38 General Commentary and Recommendations Regarding the Assessment of 

UVM programs at AEP, FE, and Cinergy 

3⁄4 Page 40 Findings and Recommendations Specific to AEP 

3⁄4 Page 46 Findings and Recommendations Specific to FE 

3⁄4 Page 52 Findings and Recommendations Specific to Cinergy 

3⁄4 Page 67 General Industry Recommendations 

3⁄4 Page 68 Recommendations for Oversight and Enforcement of UVM Activities 

3⁄4 Page 70 Recommended Best Management Practices in the Transmission UVM Industry 

3⁄4 Page 109 Recommendations Submitted by a Panel of UVM Industry Experts 

For the purposes of this Executive Summary, we are providing the following two sections of 

“key” recommendations for utility companies, and the agencies and organizations charged with 

their oversight. 

Key Recommendations for Utility Companies 

The conditions and influences that contributed to the August 14th tree and power line conflicts 

currently exist throughout the US and Canada. As we have outlined in this report, there are 

ubiquitous problems and issues that need to be addressed by utility companies, and the UVM 

industry. The following are abbreviated recommendations regarding how to improve current 

practices at utility company UVM programs 

a. Improve current systems for managing UVM workload and schedules. 

b. Ensure adequate and consistent UVM funding based on actual required work. 

c. Adopt consistent and industry-accepted Best Practices for UVM operations. 

d. With support of oversight agencies, improve public education regarding appropriate 

plantings near power lines, and in explaining the necessity of the work. 

Recommendations for Oversight and Enforcement of UVM Activities 

Current oversight of UVM activities by appropriate agencies or organizations is inadequate. 

While there is no shortage of concern regarding preventing tree and power line conflicts in the 

wake of blackouts, we believe that there needs to be a more consistent, focused, and public 

interest-based approach to overseeing the efforts of utility companies in this critical activity. The 

following are recommendations regarding how to improve current oversight and enforcement of 

UVM activities: 

a. Develop clear and consistent UVM program expectations and standards regarding utility 

company performance. 

b. Develop incentives/penalties for compliance. 

c. Enforcement and oversight should be routine. 

d. Oversight organizations need to publicly and politically support UVM activities where 

appropriate. 

ADDITIONAL INFORMATION CONTAINED IN THIS REPORT 

This report addresses all tasks identified in the original scope of this project. This includes a 

comprehensive list of UVM Best Practices that we developed with the active input, support, and 

endorsement of UVM industry experts in the US and Canada. These (and other) UVM experts 

have also graciously contributed specific recommendations they feel will address many of the 

current conditions that contribute to the likelihood of future tree and power line conflicts. 
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We believe that the attention now being focused on the critical importance of UVM could lead to 

increased safety and reliability for both electric transmission and distribution systems throughout 

North America. While we have focused our investigation and efforts into transmission UVM 

activities, we believe that many of the specific recommendations contained in this report have 

equal applicability to distribution UVM programs. 

In closing, we believe that it would be a tragic mistake, leading to a lost opportunity, to simply 

conclude that unique errors or unusually inadequate vegetation management practices were the 

sole cause of these outages. Loss of transmission lines and major outages due to tree and 

power line conflicts have occurred in the past, and they are certain to occur in the future, unless 

there are significant changes in the industry’s vegetation management practices and their 

oversight. We believe the recommendations and information contained in the report will provide 

a significant start in the right direction. 
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II. INTRODUCTION 

This report covers a wide variety of issues related to the UVM industry, and the specific UVM 

programs and practices of the utilities involved with the August 14th Blackout. Equally important, 

we have tried to address some of the issues that we believe should be evaluated in order to 

mitigate the possibility of future large-scale, tree-related outages along transmission lines in 

North America. 

The broad nature of these objectives requires us to provide a great deal of background and 

supplemental information regarding the current state of the UVM industry. This includes 

discussions on such items as the current UVM requirements and laws, and common obstacles 

to performing the work. We believe the totality of the information provided here will lead to a 

better understanding of how current conditions may have contributed to the August 14th

Blackout, and also what steps can be taken to mitigate future tree and power line-related faults 

on transmission lines. 
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III. BACKGROUND 

THE PURPOSE OF UVM: WHEN TREES AND POWER LINES CONFLICT 

It is appropriate to begin with an explanation of why a UVM program is critical to any utility 

company that maintains overhead energized lines. The three most often cited reasons for 

having a UVM program are to prevent tree-related outages, to prevent tree/power line-related 

wildland fires, and for overall public safety. 

Electric Service Reliability: Preventing Tree-Related Outages 

Tree-related outages such as those experienced on August 14th are not anomalies. In fact, it is 

generally accepted that the single largest cause of electric power outages occurs when trees, or 

portions of trees, grow or fall into overhead power lines. The odds are that every single electric 

customer in the US and Canada has, at one time or another, experienced a sustained electric 

outage as a direct result of a tree and power line conflict. 

While this is a more common problem on distribution lines, transmission tree-related outages 

are also experienced by utilities on a regular basis. For example, the following chart, provided 

by the Western Systems Coordinating Council (WSCC), illustrates the frequency of 230kV treerelated outages experienced on member utility systems in the west from 1998-2002. 

230-kV Vegetation Outage Summary 1998-2002

0

2

4

6

8

10

12

14

16

18

Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec

1998 1999 2000 2001 2002

A look at other large historical outages also clearly points to the influence of vegetation. For 

example, two significant outages in the western US in 1996 were attributed, in part, to trees. On 

July 2nd trees contacted a 345kV line resulting in an outage to 2.2 million customers and on 

August 10th trees contacted a 500kV line ultimately affecting 7.5 million customers in seven 

states. More recently, the outage that occurred in Italy on September 28, 2003 was “triggered by 

a trip of the Swiss 380kV line Mettlen-Lavorgo (also called the “Lukmanier” line) at 03:01 caused 

by tree flashover.” This tree related outage left 57 million people without power and impacted 

several other countries in Europe. Outages 
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While there is no shortage of these examples, it is important to keep these numbers in 

perspective regarding our actual exposure to tree-related outages on transmission and 

distribution systems. Utility companies in North America manage hundreds of millions of trees5

, 

and any one of them could conceivably cause an outage. To illustrate this exposure, if the total 

number of trees managed by utility companies in North America is 200 million, and the utilities 

could achieve adequate clearances on 99% of the trees, the potential6

 to experience 2 million 

tree-related outages in any given year still exists. 

Preventing Tree-Related Fires 

While not as common as tree-related outages, the issue of fires initiated from tree and power 

line conflicts is another reason that many utility companies have comprehensive UVM 

programs. Arcing between any part of a tree and a bare high-voltage conductor has the 

potential to occur if the physical separation between both is not maintained. Arcing distances 

vary based on such factors as voltage and ambient conditions. If arcing does occur between a 

branch and high-voltage line, there is the possibility that the branch could ignite and fall to the 

ground. If flammable material is present on the ground, it could cause a fire. 

Unfortunately, current fire information systems at the local, state, and federal levels do not 

accurately record or track the historic incidents of tree and power line-caused fires. So, no one 

knows exactly how big the problem actually is. What we do know is that tree and power lineinitiated fires are typically much more damaging and costly than typical wildland fires. For 

example, California fire officials have stated in the past that 1-3%7

 of the state’s wildland fires 

can be attributed to tree and power line conflicts. However, a review of major historic fires in 

California illustrates that these fires typically cause significant devastation. We believe this is 

partially related to the fact that many of these fires occur in remote areas with a larger fuel base 

of flammable vegetation. 

While fires are a significant problem and concern in both the US and Canada, it appears that the 

issue of tree and power line-caused fires is primarily an issue in the western states and 

provinces. Nevertheless, these types of occurrences have happened everywhere at one time or 

another and many fire authorities have promulgated codes to prevent them from occurring. (See 

section on “Current Requirements for UVM Work”.) 

Public Safety 

Preventing outages and fires related to tree and power line conflicts is obviously in the interest 

of public safety. In addition to preventing these types of occurrences, the act of keeping lines 

clear of vegetation also makes it easier for the public to see, and avoid, the energized lines and 

equipment. While the most effective way to prevent accidents associated with the public 

climbing trees or working near power lines is through public education and avoidance of these 

situations8

, separation between lines and vegetation increases the likelihood that the individuals 

will “see” the energized facilities before an accident occurs. 

 

5

 Given that the majority of utility companies do not currently have an inventory of all vegetation under their 

management, we have extrapolated this number from the limited data available. 6

 Trees in contact with conductors do not always generate sufficient ground fault current to cause an outage. 7

 We question this number given that California’s fire tracking system (CFIRS) does not have the current ability to 

track these causes. They are typically lumped under various causes and do not show up in any generated reports as 

tree- and power line-initiated fires. 

8

 Current mandatory clearance requirements are not effective, or practical, in preventing accidental direct or indirect 

contact with energized lines by unwary tree climbers. 
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INTRODUCTION TO THE UVM INDUSTRY AND PROGRAMS 

UVM programs represent one of the largest recurring maintenance expenses for electric utility 

companies in North America. Keeping trees and vegetation from conflicting with overhead 

conductors is a critical and expensive responsibility of all utility companies concerned about 

electric service reliability and fire mitigation. 

The vast majority of work in this multi-billion-dollar-a-year industry is not performed by utility 

personnel, but rather outsourced to specialized tree and vegetation management contractors. 

These contractors typically work under the direction of a utility company Arborist or Forester 

who is charged with overall management of the UVM program. 

A typical UVM program can include all of the following activities: 

1. Tree pruning and removal 

2. Vegetation control around poles, substations, and other electric facilities 

3. Manual, mechanical, or chemical control of vegetation along rights-of-way 

4. Pre- and post inspections of required work 

5. Tree planting and transplanting 

6. Research and development 

7. Public education 

8. Tree inventories, work management systems, and sundry computerized functions 

While this industry has been around in some form or another since the first tree caused an 

outage on overhead lines, it is still relatively immature in many respects. For example, there still 

remains a wide spectrum of competence between how UVM activities are handled at each 

utility. There are many utilities that have comprehensive, well-funded, and very effective 

programs. Conversely, there still remain utilities that pay little attention to this important activity. 

They opt instead to look at UVM as a function best handled by the contractors. 

TRANSMISSION AND DISTRIBUTION (T&D) UVM ACTIVITIES 

While this investigation has focused on transmission UVM activities, it is important to note the 

relationship with distribution UVM operations. This discussion is necessary in that most utility 

companies have one program that deals with both transmission and distribution UVM activities. 

Additionally, many lower voltage transmission poles have distribution circuits located on them. 

This is typically referred to as “under-build facilities.” While T&D UVM operations frequently 

share the same administration and oversight, there are important differences in the potential 

risks and general differences in the type of work that is performed. The following is a brief 

description of the types of work associated with each of these UVM programs. 

Distribution UVM

Distribution Systems are Much Larger: By far, distribution UVM activities comprise the largest 

part of an electric utility’s efforts in managing trees and vegetation near power lines. At many 

utilities, the distribution part of a program may utilize 80-90% of utility funding and resources for 

managing vegetation. This does not however mean that distribution UVM is any more important 

than transmission work, but rather, it is a by-product of having significantly more miles of 

distribution lines (and exposure) than transmission lines. 

Distribution UVM is Typically More Public, More Complex and More Expensive: Distribution 

programs typically prune more trees than they remove, and the costs (on a per tree basis) are 

higher than equivalent work on transmission lines. This is primarily due to the fact that most 
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distribution tree pruning or removal is done in front of someone’s home, and on community 

streets. Distribution UVM work is more visible to the public, and as such, requires more upfront 

notification, coordination with agencies, and a greater amount of personal and public education 

prior to commencing the work. 

Transmission UVM 

Transmission UVM has Better Defined Rights to Perform Required Work: The primary 

difference between transmission and distribution UVM work can be summed up as follows. The 

vast majority of transmission rights-of-way (ROW) have documented provisions allowing the 

utility to clear and maintain the vegetation in order to provide safe and reliable electric power. 

These ROW easements give the utility a greater amount of control over the landscape than 

what is experienced adjacent to distribution lines. In the latter case, little if any documentation 

exists giving the utility the “specific” right to perform whatever UVM work is required to maintain 

the distribution lines free of vegetation. 

Greater Risk of Arcing at High Voltage and Less Pruning: Given the greater rights associated 

with transmission UVM work, and the necessity of maintaining greater clearances due to higher 

voltages, it is common to see less pruning and more removals related to transmission work than 

are typically seen in a distribution program. The unit costs are also typically lower for 

transmission UVM work than are experienced in distribution activities (due in part to fewer 

customers and landowners to negotiate with). These documented rights also result in greater 

use of mechanical and chemical UVM tools on transmission rights-of-way. This includes various 

types of mechanical mowers and the wider use of appropriate herbicides. 

CURRENT REQUIREMENTS FOR UVM WORK 

There are a wealth of laws and regulations that encourage and/or direct utility companies to 

work toward the mitigation of transmission line outages. However, this direction is typically nonspecific regarding UVM efforts. It appears that rather than rely on prescriptive requirements 

(telling utilities exactly how to achieve electric service reliability) most applicable laws and 

regulations are generic in their direction to utilities. The following example illustrates this point: 

Performance Based Ratemaking generally relies on encouraging utilities to meet or 

exceed performance goals (e.g., reduce outages). Rather than specifically require that 

all trees be maintained at a specific clearance, it is assumed the utility understands that 

one of the biggest threats to service reliability is trees and vegetation. Therefore, the 

utility would presumably work toward preventing these types of outages in order to 

achieve the defined goals. 

While most laws, regulations, and incentives requiring UVM work are non-prescriptive, there are 

several current guidelines and regulations that mandate this work under certain circumstances. 

The National Electric Safety Code (NESC) Rule 218 

The NESC Rule 218 is the most widely adopted and referenced set of guidelines for UVM 

programs in the United States. It currently states: 

A. General 

1. Trees that may interfere with ungrounded supply conductors should be trimmed 

or removed. Note: Normal tree growth, the combined movement of trees and 

conductors under adverse weather conditions, voltage, and sagging of 
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conductors at elevated temperatures are among the factors to be considered in 

determining the extent of trimming required. 

2. Where trimming or removal is not practical, the conductor should be separated 

from the tree with suitable materials or devices to avoid conductor damage by 

abrasion and grounding of the circuit through the tree. 

B. At Line Crossings, Railroad Crossings, and Limited-Access Highway Crossings. The 

crossing span and the adjoining span on each side of the crossing should be kept 

free from over-hanging or decayed trees or limbs that otherwise might fall into the 

line. 

The NESC Code has been adopted by most Public/State Utility Commissions by rule, and is 

used to provide direction and standards for electric utility companies. In the case of Rule 218, it 

has generally been interpreted as a set of guidelines that the utility should use in defining their 

UVM activities and goals. 

At first glance, Rule 218 seems clear in its intent, but it has historically generated a great deal of 

industry discussion regarding what it actually requires. For example, the use of the word 

“should” versus “shall” points to its application as a general guideline, not a mandate. More 

importantly, Rule 218 does not specifically state that clearances should be “maintained” 

between energized lines and vegetation. While some have argued that it can be interpreted as a 

“no-touch rule”, the industry has not interpreted it to require that mandatory clearances be 

maintained at all times. 

Note: Rule 218 of the NESC is currently being reviewed by industry organizations to update and 

clarify the requirements. Having reviewed various proposed drafts, we believe the upcoming 

changes will help in clarifying the requirements for utility companies, and in providing better 

direction for managing vegetation adjacent to power lines. 

Mandatory Clearance Requirements 

California: Based on a 2002 national review9

 of laws and regulations, the California Public Utility 

Commission (CPUC) is the only utility regulatory body in the United States to have adopted 

mandatory clearance requirements10. California utilities must achieve and maintain prescribed 

clearances between high-voltage lines and any parts of trees or vegetation. This requirement is 

in effect 24 hours a day, 7 days a week, and is applicable in all Commission regulated areas of 

the state. Typical clearances that must be maintained between vegetation and transmission 

lines are: 230kV – 31.7 inches, 345kV – 84 inches, 500kV – 120 inches. The text of this rule 

(General Order 95, Rule 35) can be found in Appendix ‘A’. 

Alberta: The Province of Alberta has also promulgated mandatory clearance requirements. They 

can be found in the “Electrical Protection Act, Section 3.1.7 of the Alberta Electrical and 

Communication Utility Code. (See Appendix ‘B’ for the full text.) 

Fire Prevention: While mandatory clearance requirements are not typical in Commission-based 

regulations, they are becoming commonplace in fire prevention requirements. As previously 

mentioned, trees or vegetation growing close to or contacting energized lines have the potential 

to start wildland fires. In an effort to prevent these occurrences, many local governments have 

 

9

 Non-published survey conducted by the authors to determine the extent and nature of UVM requirements in the 

United States. 

10 Oregon has a “staff policy” that has been interpreted by some as a mandatory clearance requirement. 
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adopted and enforce mandatory clearance requirements. Common mandatory clearance 

requirements can be found in the Uniform Fire Code (UFC) and the Urban Wildland Interface 

Code (UWIC). These are both “model” codes developed by the International Fire Code Institute 

(IFCI) and adopted locally (or at a state level) as the standard community fire code. The text for 

mandatory clearance requirements taken from the Urban Wildland Interface Code can be found 

in Appendix ‘C’. 

The key differences between the CPUC mandatory clearance requirements and those found in 

fire codes are related to the timing of enforcement and the geographic areas in which they are 

applicable. The CPUC requirement is applicable 365 days a year and is enforced throughout the 

state. The fire codes, on the other hand, are only applicable at times and in locations deemed 

appropriate by the fire official. For example, mandatory clearances for fire protection are not 

typically enforced during winter when the ground is covered by snow, or in downtown locations 

where no flammable ground cover is present. 

Mandatory Clearances as a Way to Mitigate Future Transmission Tree-Related Outages 

There are compelling arguments that suggest mandatory clearance requirements will not 

eliminate tree-line contacts. In fact, it can be argued that their adoption can create more 

problems than they may resolve. The following are several issues that should be addressed 

before adopting these types of standards. 

1. Efficacy: We do not know if mandatory clearance requirements would prevent all treerelated outages. We do know that they should eliminate tree outages that are caused by 

“growth.” However, the majority of tree-related outages in North America are caused by 

trees or portions of trees falling into lines from distances that are typically located outside 

of what would be considered normal clearing zones. In other words, the biggest threat 

from trees is not presented by growth into a clearance zone, but rather by trees located 

outside of what would normally be pruned or removed. 

2. Enforcement: In order to enforce mandatory clearance requirements, there must be no 

ambiguity regarding clearances encountered in the field. For example, if the standard 

says, “maintain 18 inches from 12kV lines” (as in California’s Rule 3511), it should be a 

relatively easy task to identify any violations in the field. While this is possible for 

distribution line clearances, transmission lines present a different challenge due to 

greater conductor sag and sway considerations. To enforce specific mandatory 

clearances on transmission lines, one would need to either inspect the lines at the 

maximum loading, or make complex calculations during the inspection to determine the 

maximum sag. 

3. Cost Concerns: The adoption of mandatory clearance requirements in California 

resulted in a tripling of UVM costs for utilities. If such rules spread, the current annual 

multi-billion dollar figure needed to keep trees away from transmission and distribution 

power lines could increase significantly. 

We do not know if the adoption of mandatory clearance requirements, in and by itself, would 

have prevented the type of tree-related incidents that occurred on August 14th. We have not 

performed, and are not aware of, any studies that have evaluated the efficacy of mandatory 

clearance requirements in preventing outages. However, if the utilities that experienced outages 

on August 14th had maintained certain clearances, based on system conditions such as load 

and ambient air temperature, it is unlikely that the outages would have occurred. These outages 

 

11 Fines can be levied against utilities in California for each violation of clearance requirements. 
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were caused by tree growth as opposed to some other condition outside of the right-of-way, and 

may have been prevented. 

It is our opinion that a change in standards as significant as adopting mandatory clearance 

requirements will likely be controversial, with opponents arguing that such action could 

significantly raise energy costs to all consumers, without guaranteeing any major improvement 

in electric service reliability. 

There are, nonetheless, valid arguments that mandatory clearance requirements would address 

some of the current industry problems. For example, in our experience mandatory clearance 

requirements have resulted in more adequate and consistent funding of UVM activities. They 

have also increased focus on these important activities, because failure to comply will often 

result in heavy penalties for the utility company. 

We do not, however, believe that mandatory clearance requirements should be adopted without 

a further investigation into their efficacy, enforceability, and cost effectiveness. Our preferred 

approach to the development new standards and oversight of UVM operations is found in 

Section VI of this report. 

Enforcement of “Cycles” 

We are aware of one state regulatory body that has chosen to motivate and track UVM efforts 

by insisting that the utilities comply with specific vegetation management “cycles”. We do not 

think that this is an appropriate method to ensure that all potential problems are addressed in a 

timely manner. In the following sections we will provide the rational for this, in addition to 

presenting information specific to the day-to-day impacts of UVM operations in both the US and 

Canada. 

In order to understand the reasons why a cycle is not an sufficient remedy, it is important to first 

understand what a “cycle” actually is. 

A “cycle” is a loosely defined term used by utility arborists to generally describe the time it takes 

to complete identified pruning or removal of certain trees on their entire electric system. 

The following will illustrate how the term is typically used in the UVM industry. 

The majority of utility companies have a systematic approach to scheduling routine work. Some 

use simple geographic grid systems, and others use the actual electric circuits for developing 

their work schedule. For example, let us assume that they schedule their work by electric circuit 

and that they have a total of ten circuits on their system. On day one, they begin patrolling the 

first circuit to identify required UVM work. As the work is identified, it is given to the UVM 

contractors to complete. After the first circuit is completed, the process starts all over on the 

next scheduled circuit12. This process proceeds sequentially until all of the circuits have been 

patrolled and the required work has been completed. If it took seven years to identify and then 

complete all of the required work, the utility would be considered to be on a seven-year cycle. 

The actual spread for utility cycles industry-wide is anywhere from 1 to 10+ years. This wide 

divergence in “cycle lengths” is due to an extensive list of influences that are often 

uncontrollable and unpredictable. Examples include: 

 

12 In this example, only one circuit is worked at a time. In reality, much of the circuit work is done concurrently. 
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Available Water: Water availability is probably the single largest determinant as to how fast a 

tree will actually grow. Withholding water will slow growth. An increase in water (particularly 

after a period of drought) will dramatically increase growth. This is a particularly important issue 

to address in drought-plagued areas of the US and Canada. For example, in the latter part of 

the 1980’s, California suffered an extended and severe drought period that lasted several years. 

The impact on the general population of trees was a slowing of growth rates. This initially had a 

positive effect on utilities in that, as they were patrolling on their routine cycle, a significantly 

fewer number of trees required pruning. Unfortunately, the drought was followed by 

unprecedented rainfall that resulted in explosive growth throughout the impacted area. (This 

issue will be discussed in depth in the Precipitation and Tree Growth section.) 

How this impacts cycles: Drought and increased rainfall can have a significant impact on cycles, 

particularly if the resources to perform the work remain static. For example, during an extended 

drought, tree growth is slowed, requiring that fewer trees need to be pruned on any given cycle. 

If fewer trees are pruned, the cycle will be shorter. Conversely, if rapid re-growth is experienced 

throughout a service territory, significantly more trees will need to be pruned, thereby extending 

the length of the cycle. 

Other Environmental Influences: The urban and rural forests are routinely bombarded by 

various environmental threats. For example, Dutch Elm disease all but decimated the elm trees 

across the US. Sudden Oak Death currently threatens to kill large populations of trees in the 

West. Pitch Canker is another pathogen threatening conifers. As a result of an extended 

drought in Arizona and southern California, millions of trees have died or are in various stages 

of decline. Large populations of dead and dying trees are a threat to electric reliability. 

How this impacts cycles: The trees in jeopardy, more often than not, are located near power 

lines. If a utility company has large populations of dead and dying trees near their lines, it has a 

responsibility to mitigate the additional threats to electric service reliability. With a typically fixed 

amount of resources, the utility must, out of necessity, prioritize the work that must be 

completed. If the choice is between continuing on a routine cycle or removing immediate 

hazards, the utility will typically address the emergency conditions first. If this occurs, the cycle 

certainly will be extended. 

Shifting Priorities: Utility companies are under continual pressure to balance available 

resources with ever-changing priorities. For example, a utility company cannot predict whether 

or not its service territory will be hit with a massive storm three years from now. It is equally 

impossible to predict if thousands of poles, connectors, transformers, or other equipment will be 

found to have manufacturer defects and require replacement next year. As in the case of 

drought-killed trees, utility companies continually deal with an ongoing stream of emergencies 

and shifting priorities. With a limited budget, every utility must routinely adjust funding based on 

reasonable and changing priorities. For most UVM programs, this means that some years they 

will get additional funding, some years they will remain flat, and some years they will see a 

reduction of resources in order to address other more urgent priorities. 

How this impacts cycles: If the UVM program receives additional funding (and they are not 

facing additional workload due to any previously mentioned anomaly) the cycle time should be 

reduced. If the UVM program funding is reduced, the cycle time may be extended. 

Cultural and Regulatory Influences: While few people would argue against the necessity of 

UVM work, this does not translate into the utility being able to do whatever it feels is appropriate 

regarding the trees. The utility does not own the trees. In many cases, utility companies must 
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adjust the amount of time and resources devoted to UVM work based on new legal 

requirements or changing industry standards. For example, communities across the country 

routinely adopt new tree ordinances. Many of these ordinances contain elaborate requirements 

for tree pruning and removal. These can include waiting periods, public meetings, and arborist 

reports before the required work can proceed. 

How this impacts cycles: If new time-consuming requirements are added, UVM work will slow 

down and result in an extended cycle, again without regard to actual reliability needs. 

How Does a Cycle Influence When a Tree Must be Pruned? 

A “cycle” has very little, if anything, to do with when an individual tree must be pruned. The only 

connection is that the tree will typically be evaluated at least once during any given cycle. More 

to the point, some trees are pruned several times during any given cycle, and others will not be 

pruned for several cycles. The determination as to when a tree needs to be pruned or removed 

is (or should be) based on a tree- and site-specific inspection. And to be clear, each and every 

tree is completely different. Two identical species of trees, planted at the same time and located 

a mere 10 feet apart can differ by years as to when UVM work is actually required. Here is a 

very short list of the actual determinants of when a tree requires pruning or removal: 

a. The location of the tree in proximity to the conductors: A tree planted directly 

underneath the conductors will require pruning at different intervals than the same aged 

species that is planted next to the conductors. 

b. The anticipated growth rate of the species: Some species are known to be fast 

growing and some slow. 

c. Available water: As previously mentioned, growth of individual trees is largely 

determined by available water. A tree planted in someone’s front yard, that is never 

watered, will require less frequent pruning than an identical tree next door that is 

routinely watered as part of the landscaping. 

 

d. Tree structure: Decurrent (typically rounded looking) trees are candidates for 

directional pruning, which can effectively direct the growth away from the conductors. If 

the tree is adjacent to the lines (planted to the side of the conductors) this clearance 

might last in excess of 15 years. However, if the same tree is located directly beneath 

the conductors, the clearance may only last a fraction of the time. Excurrent (typically 

one main trunk) trees cannot be readily directionally pruned. 

e. The perceived threat to the electric lines: If there are two identical trees and one of 

them is dead and leaning toward the line, it will be worked sooner than the healthy tree. 

f. The affected utility lines and equipment: Utilities typically prioritize work based on 

such items as the line voltage, number of customers who could be impacted by an 

outage, and the geographic areas involved. For example, protecting transmission lines 

would receive a higher priority than an isolated distribution line. In this example, the 

transmission lines have a greater likelihood of arcing (due to the higher voltage) and 

would likely have a larger impact on customers, should a tree related outage occur. 

These six items only touch on a few of the myriad influences that actually dictate when UVM 

work should occur. 
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Given the countless influences, and the historical inability to track and manage them from a 

technological and informational standpoint, we do not believe that adherence to a “cycle” is an 

appropriate measure of a utility company’s efforts. While the term “cycle” is still used in the 

industry, we are not aware of many utility companies that can claim they have “been on a 

consistent cycle” for any extended period of time. A cycle is, and always has been, a moving 

objective. Our preferred approach to the development of new standards and oversight of UVM 

operations is found in Section VI of this report. 

IMPEDIMENTS TO COMPLETING REQUIRED UVM WORK – COMPETING INTERESTS 

When we asked more than 50 utility companies in North America to list the government entities 

that “influenced” their UVM activities, we received the following response: 

69% Requirements by State Highway departments 

58% Requirements relating to local street tree ordinances 

58% Rules specifically mandated by State Public Utility Commissions 

46% Requirements related to “other” local ordinances 

44% USFS/BLM or other federal agency requirements 

42% NESC Rule 218 

38% Other State mandated laws 

18% Urban Wildland Interface Code 

16% Uniform Fire Code 

12% Other local fire codes 

While these responses were from both transmission and distribution utility arborists, they do 

illustrate the significant problem of “competing interests” when it comes to performing required 

UVM work on transmission lines. 

The problem can be summarized as follows: 

• Utilities have the obligation to manage vegetation near transmission lines in order to provide 

safe and reliable electric service. 

• This objective sometimes appears to conflict with other various interests on a local, 

state/provincial, and federal level. 

Specifically, utility arborists look at the vegetation adjacent to power lines as a threat to service 

reliability and public safety. This same vegetation is viewed, by various other agencies and 

authorities, as primarily intended for landscaping, habitat, a community resource, a timber 

supply, etc. For many of these groups, the necessity of keeping the lines clear is subservient to 

their own requirements and authority. 

A subtle yet tangible example of this conflict can be seen in the following DRAFT code language 

that has recently been proposed by certain highway/roadway officials. The proposed language 

states: 

"Appropriate trees should be selected for planting underneath overhead utility lines. 

Where space is available, larger trees should be planted along on the outside of the 

utility lines clearance area, with smaller trees underneath. This provides for the best 

opportunity to minimize the visual intrusion of the overhead utility line." 
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While the intent of that language may have been noble, it provides a clear example of how 

imprecise language can make a bad situation worse. Rather than recognize the necessity of 

overhead utility lines, this language stresses the need to minimize their “visual intrusion” by 

planting small trees underneath the lines, and larger trees adjacent to them. Unfortunately, a 

small tree can mean a giant sequoia in a 5-gallon bucket, and a large tree can be any species in 

a large container. If this language is adopted, and the suggestions implemented along 

transmission corridors, it will likely result in future outages and wasted money spent trying to 

keep the trees away from the lines. 

This of course is not to say that all code language has been bad, or that it is not effective in 

reducing tree and power line conflicts. Many local tree ordinances and fire codes recognize and 

effectively address the problem of future tree and power line conflicts. A particularly good 

example of positive language can be found in the Urban-Wildland Interface Fire Code. It simply 

states that “no trees or vegetation can be planted that will grow within 10 feet of an energized 

line at maturity” (primarily applied to electric distribution, not transmission facilities or ROWs). 

This simple language, if adopted globally, would reduce the future likelihood of countless 

outages and fires, save a great deal of ratepayers’ dollars, and actually improve the health and 

longevity of trees and vegetation by eliminating unnecessary pruning and removals. 

In the following section, we will further discuss how various authorities and agencies also 

contribute to impeding required UVM work. 

THE URGENCY OF THE WORK 

The intent of any UVM program is to address the trees and vegetation before they become a 

problem. For example, when a tree is pruned for clearance, the intent on the part of the utility is 

to return to that tree right before it needs to be re-pruned. To prune it before it actually needs repruning can damage the tree and may waste money (if it really doesn’t need to be pruned for 

another year or so, it makes sense to devote the available resources to address other, more 

immediate work). This balancing act often means that a utility will not re-work the tree until it is 

either already a threat to the lines, or will be in a few short months. 

The difficulty in this situation is as follows. If the utility companies wait to schedule a pruning 

target until it is on the verge of becoming a problem, there is only a short period of time between 

identifying the required work, and completing it before it can result in a potential outage or fire. 

Unfortunately, this short period of time is not often recognized as a legitimate concern by many 

of the groups or individuals who actually own the trees. Here are several examples of problems 

provided by utility arborists: 

Location: Maryland 

Utility: Large Investor Owned 

Incident: “One of the utility's contractors followed protocol to notify property owners 

about impending distribution tree pruning and selective removal activities. Door hangers 

were distributed in advance of the work and signed permission cards were obtained from 

property owners to allow for tree removals. A local (third party) resident complained 

about the pruning aesthetics and about the amount of tree removals in the area. Local 

elected officials were mobilized and interceded to have the tree work halted until an 

investigation by a State agency could be conducted. The agency performed the 

investigation as directed. The State agency alleged that the contractor trimmed in 

excess of the ANSI A-300 Pruning standard in many instances and violated various 
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aspects of another law governing trees on public rights-of-way. The utility challenged all 

of the allegations in their response, and continued negotiations with the State agency 

and the elected officials were required. The outcome was that most of the pruning issues 

were generally dismissed. Where trees were removed with property owner permission, 

the utility agreed to replant trees on the State right-of-way. In situations where the State 

was not willing to dismiss the pruning complaints on public rights-of-way, the State 

agreed to issue removal permits and the utility agreed to provide tree replacements. 

Total elapsed time of the work stoppage was approximately 1 year, and numerous 

storms occurred during the work stoppage.”

Location: California 

Utility: Large Investor Owned 

Incident: “The local Public Works Director stopped the utility from completing identified 

and required UVM work on city trees in this particular community. The Public Works 

Director said he was getting too many phone calls complaining about the directional 

pruning and wanted the utility to stop for a few months till things settled down. The utility 

wanted to proceed but was told they could not prune any of the additional trees that had 

been identified as requiring work. Within two weeks, one of those trees caused a rather 

large outage that just happened to take out power to a good portion of this town 

(including City Hall). The Public Works Director immediately called the utility and told 

them to continue to do whatever pruning and removal was necessary to ensure they had 

no more outages.” 

Location: Arizona 

Utility: Large Investor Owned 

Incident: “Two examples of the Arizona utility not getting adequate clearance on the 

high voltage lines are as follows: The first is found on the Tonto National Forest where 

individuals limit the amount of clearance the utility can obtain. The utility has 176 acres 

of trees that could affect the reliability of the system under maximum load conditions. 

The utility has been working with the Forest Service at all levels from the District 

Forester, Forest Supervisor, Regional Forester and the Chief of the Forest Service to get 

a consistent vegetation management approach across all federal lands. The utility began 

this process in 1997 and to date has not been able to get a science-based approach on 

federal lands. The utility has finally gotten the Forest Supervisors in Region 3 to put 

together a working group to address these issues. 

The next example is on the Navaho Nation which prevented the utility from removing 

trees over 9” in diameter at breast height (DBH) due to the Mexican Spotted Owl. The 

utility has 370 trees that could affect system reliability under loaded conditions. The 

utility has been working with the Navaho Nation to get these trees removed since 1998. 

The utility finally got approval from the Navaho forestry department to remove these 

trees on October 20, 2003. After one week of cutting, the Navaho Nation environmental 

department shut down our crews because they were not consulted.” 

It should be noted that we make no claim as to the accuracy of the facts behind any of the 

preceding examples. We have not been able to validate any of any of these occurrences and 

only include them as examples of the types of issues that are routinely encountered throughout 

North America. 
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THE INFLUENCE OF INDIVIDUAL PROPERTY OWNERS 

Approximately 1-3% of all property owners who are notified of pending UVM work on their 

property initially refuse to allow the utility the right or access to perform the work. Fortunately, 

the majority of these “refusals” are resolved after further negotiations with the utility. 

Unfortunately, there still remain a small percentage of individuals who successfully stop the 

work. Such work stoppage, combined with current UVM scheduling methods by utilities, can 

temporarily increase the likelihood of outages or fires. The reasons for these refusals are 

numerous and can range from concerns over aesthetics to negative prior experiences with the 

utility and/or contractor. 

While the percentage of refusals capable of causing problems (before being resolved) is 

estimated to be less than 1%, we need to recognize how that actually translates into exposure. 

To illustrate, if a utility manages 1 million trees adjacent to or under transmission lines, and is 

stopped from working on one-half percent of the trees, there could conceivably be 5,000 trees 

capable of causing a problem at any given moment in time. This exposure needs to be 

multiplied by the numerous utility companies who do indeed manage over a million trees in the 

US and Canada. 

The issue, and exposure, of individual refusals is best illustrated by reviewing the outage that 

occurred on August 14th on Cinergy’s Columbus – Bedford 345kV line (see Appendix ‘D’ for a 

detailed description of the incident). Had this refusal been on one of the lines that contributed to 

the blackout, it could have been accurately stated that an individual landowner was, from one 

perspective, largely responsible for triggering one of the worst outages in North American 

history. 

Work on this span on the Columbus – Bedford 345kV line had been halted various times by the 

owner of the property. The owner of the property had severely limited the ability to achieve 

necessary clearances and to apply herbicides to control future growth. This landowner has 

successfully halted work from proceeding on several occasions. This included the homeowner 

obtaining a court-granted temporary injunction against the utility. 
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The required work was finally completed on October 9, 2003 as depicted in the photo below. 

Another significant influence by individuals (and agencies) simply relates to planting the wrong 

trees in the wrong place. A very large percentage of trees that are currently managed by utilities 

simply do not belong there because they are too large and will, at maturity, cause conflicts. 

There are countless lower-growing species that can be safely planted and never require costly 

pruning or removal. We believe that if the public simply planted the right tree in the right place, 

hundreds of millions of dollars could be saved annually in unnecessary UVM maintenance 

costs, outages and fires would be significantly reduced, and the actual health of urban and rural 

forests would be dramatically improved. 

TRANSMISSION RIGHT-OF-WAY (ROW) MAINTENANCE 

As previously mentioned, transmission UVM work typically differs from what would be found 

adjacent to distribution power lines. Distribution UVM work is dominated by pruning and 

removing trees adjacent to distribution poles, which in most cases are in more populated areas. 

Conversely, transmission lines are typically located on towers and typically in more remote 

areas. 

As a general rule of thumb, the higher the voltage, the more sensitive the line will be to treerelated faults. For example, uninsulated low voltage secondary lines (120/240 volts) can come 

in direct contact with vegetation and it will be highly unlikely that an electrical outage will occur. 

The same can be said for most typical primary voltage lines carrying 4-12kV. However, as we 

reach higher transmission voltages, the likelihood of an outage, due strictly to contact, is 

exponentially increased. As a result, utilities maintain typically larger clearances between 

vegetation and transmission lines than would be seen on a typical distribution line. Generally 

speaking, the higher the voltage, the higher the lines will be located above the ground, and 

away from the vegetation. 
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The following photos depict typical transmission and distribution facilities. 

Transmission Line 

Distribution Line 

High Voltage Distribution 
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Ideal ROW Maintenance – Industry Consensus 

There is industry consensus as to how a transmission ROW should be established and 

maintained. From an electric reliability standpoint, it simply requires managing vegetation so 

that it cannot grow into, or fall onto the energized facilities. It requires creating a predictable and 

low-growing environment of vegetation under and adjacent to the ROW. The following graphic 

illustrates this simple concept. 

Bramble and Byrnes Wire Zone – Border Zone 

(From Yahner, Bramble and Byrnes, 2000) 

As the graphic describes, this concept is typically referred to as the Wire Zone - Border Zone 

model, and it has, based on years of research13, been proven to be effective in reducing and/or 

eliminating outages related to vegetation on transmission ROWs. In addition, this research has 

proven that the Wire Zone - Border Zone model generates a great many more benefits than just 

reducing outages. These benefits include reduced long-term maintenance costs, improved 

habitat for wildlife, biodiversity, and wildland fire mitigation. 

While we recommend that this model be used wherever possible, there are locations where this 

may not be practical. There are locations where transmission lines are not located on clearly 

defined and documented ROWs. These lines may also be located in more urban areas where 

the Wire Zone - Border Zone model may not be appropriate due to existing landscaping or 

property lines. With that said, we do believe that this model should be utilized whenever new 

lines are built, and wherever existing lines will allow. This model could and should be applied to 

the vast majority of transmission lines. 

Reclaiming ROWs 

The steps to effectively managing a transmission ROW from a UVM perspective are: 

1. Design the line and obtain necessary easements and permits. 

2. Build the line and establish the Wire Zone - Border Zone vegetation model utilizing 

appropriate Integrated Vegetation Management (IVM) techniques14. 

 

13 Example: Bramble, W.C., W.R. Byrnes, R.J. Hutnick and S.A. Liscinsky. 1991. Prediction of cover type of rightsof-way after maintenance treatments. Journal of Arboriculture. 17:38-43. 14 IVM is generally defined as the practice of promoting desirable, stable, low-growing plant communities that will 

resist invasion by tall growing tree species through the use of appropriate and environmentally sound control 

methods. These methods can include a combination of chemical, biological, cultural, and/or mechanical treatments. 
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3. On a scheduled and routine basis, return to the ROW and perform the necessary UVM 

work to “maintain” the vegetation consistent with the Wire Zone - Border Zone model. 

Unfortunately, there are many locations throughout North America where this ideal cycle has 

been broken and resulted in overgrown and unmanageable transmission ROWs. It appears that 

this breakdown occurs when it comes to step three. While we know that routine scheduled 

maintenance on existing ROWs is cost-effective in the long-term15, many utilities have allowed 

these Wire Zone - Border Zone areas (once established) to grow back. Once they have grown 

back, they require an even greater effort and expense to re-establish, or reclaim, what could 

have been simply maintained on a regular basis. 

The reasons for this can be numerous, and occasionally out of the control of the utility. 

However, the utility may have also made a poor long-term decision to simply not perform the 

work in order to focus on more immediate issues, or to reduce short-term costs. Regardless of 

the reasons, the issue of not maintaining ROWs on a routine basis is relatively common in the 

industry. 

Fortunately, many utility companies have recognized this problem and are taking active 

measures to “reclaim” these ROWs. Unfortunately, reclaiming ROWs is often a difficult and 

costly process. One example of these difficulties arises when a landowner plants landscaping 

within the ROW and the utility allows it to exist over an extended period of time. This problem is 

illustrated in the following picture taken a few spans away from the fault location that occurred 

on the Hanna – Juniper 345kV line. 

Above, the landowner has planted a row of trees directly underneath the transmission lines. If 

the utility chooses to enforce the documented easement rights, it would be able to remove this 

 

15 Considerable research has been done that demonstrates that while initial clearing costs might be higher, they are 

usually reduced, and recouped, over time. It has also been demonstrated that “deferred” UVM maintenance will result 

in considerably higher long-term costs compared to just performing “routine” maintenance. 
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landscaping. Unfortunately, this would most likely cause a great deal of controversy between 

the utility and the landowner, and adjacent neighbors who would obviously notice the difference. 

This could lead to lengthy court proceedings in order to enforce those rights or create negative 

publicity for the utility company16. It is the anticipation of these types of occurrences that often 

complicates reclaiming transmission ROWs. 

The issue of reclaiming ROWs should be important to the individual utilities, their regulators, 

and to the community at large, as it directly relates to the long-term cost-effective delivery of 

reliable power to the public. However, we need to recognize that these efforts are not a simple 

matter of just removing a large amount of trees and vegetation. Many influences can, and often 

do, limit the ability of a utility company to have 100% of their ROWs managed under an ideal 

model. Some examples of absolute and restrictive easement rights are contained in Appendix 

‘E’. 

PRECIPITATION AND TREE GROWTH 

As previously mentioned, available water can have a dramatic influence on the growth of trees 

and other vegetation. We were asked to investigate whether or not these environmental 

conditions that affect growth played a role in the August 14th Blackout. 

The short answer to the question is that we do not believe that the small increase in rainfall in 

2002 was significant enough to have required the utility to increase or accelerate pruning efforts 

in an attempt to mitigate a potential outage. The rainfall data (see Appendix ‘F’) show that while 

certain subject areas did experience above and below normal rainfall in the preceding threeyear period, it was very close to normal in all years and was not significant enough to cause 

concern with respect to accelerated tree growth. The average rainfall, indicated as a percent of 

normal, for all areas reviewed is shown below: 

2000 - 104% 

2001 - 98% 

2002 - 102% 

2003 - (January through June) - 96% 

This review suggests that rainfall was close to normal in the three years prior to the outage and 

therefore we believe it did not play an important role in contributing to the outages. While it is 

possible that a few particular species of trees may have shown increased growth, we do not feel 

this phenomenon would have manifested itself over the larger population of vegetation 

managed by any of these utilities. 

The Industry Needs to Improve Their Understanding of How Available Water and Precipitation 

Can Influence UVM Programs: Our review did identify an important concern. We do not believe 

that the UVM industry actually considers precipitation to the extent necessary to effectively 

schedule work and adequately fund transmission UVM activities. As explained by Dr. David 

Wood in his report (see Appendix ‘G’), available water can significantly alter the amount of 

required UVM work that a utility must perform in order to keep up with growth. Add to that the 

impact that drought can have on tree mortality, and we cannot escape the fact that available 

water and precipitation must be considered by utilities when they develop short and long-term 

plans for transmission UVM work. 

 

16 This is a common problem for utilities. For example, recent news articles have illustrated this point with FirstEnergy 

in their attempts to become more aggressive in their tree pruning and removal efforts in the aftermath of the August 

14th Blackout. 
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To illustrate the impact of available water on UVM programs, one only needs to look at southern 

California and Arizona during the past two to three years. As a result of extended droughts, both 

areas are currently facing massive tree mortality adjacent to electric T&D facilities. In southern 

California alone, utility companies are expected to spend several hundred million dollars over 

the next few years in order to remove dead trees that could fall into power lines and equipment 

(causing outages and/or fires). Arizona faces an equally severe problem of tree mortality in the 

largest contiguous pine forest in the United States. 

Conversely, we are aware of at least one utility that was unprepared for explosive tree growth 

across a significant portion of its service territory, following an extended period of drought. In 

this case, the utility was required to employ extraordinary efforts to try and keep up with an 

onslaught of rapidly growing trees. 

We do not believe that the industry currently considers available water to the extent they should 

in planning for, and responding to, required UVM work. There does not appear to be a good 

scientific model to accurately predict the influence of available water on the large populations of 

vegetation currently managed by utility companies. This is an important issue that needs to be 

addressed and recommend that the industry work toward the development of appropriate 

predictive models based on rainfall and available water data. 

UVM FUNDING AND WORK MANAGEMENT 

To develop an annual UVM budget, a utility must be able to answer the following two basic 

questions: 

1. How much vegetation needs to be removed, pruned, or treated to prevent outages and 

fires? 

2. How much does it cost to complete each unit of work? 

If you know how much work you need to complete, and you know how much it should cost, it is 

simply a matter of multiplication. 

Unfortunately, few utilities can answer the first question with any certainty. In fact, the vast 

majority of utility companies do not have an accurate inventory of the vegetation they manage, 

but rather rely on historic and often anecdotal work histories. For example, their forecasting 

ability could be limited to “the last time we did that circuit, it took us three months with four 

crews.” This method of forecasting does not consider the myriad variables that continuously 

change the base workload. This status quo approach does not take into consideration such 

factors as precipitation, past tree removals, species growth rate variability, or new trees added 

to the base workload. All these influences significantly alter exactly how much work is necessary 

to be completed in a given timeframe. Simply put, the majority of utility companies cannot 

answer the fundamental question of “how much work do they actually need to perform?” 

It has only been in recent years that the technology17 has existed to develop and maintain 

accurate UVM inventories and systems capable of monitoring these millions of pieces of 

information. Of the small number of utilities that do currently have an accurate inventory and 

work management system, most have had to develop this technology internally. These utilities 

 

17 Database management tools that schedule work, track assignment and completion of work, billing, and other 

pertinent data. 
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have invested a great deal of money in the development of their systems, and have also had to 

invest in the costly and formidable task of accumulating the required data. 

All medium and large utility companies should seriously consider the investment in inventories 

and work management systems. The argument for this expense is simply this: If one tree can 

take out power to millions of people and cost billions of dollars in lost revenue and damages to 

society, isn’t it worth spending a few dollars per tree to document information that may very well 

prevent the incident from happening in the first place? We also believe that the cost for these 

systems will be reduced as more utilities opt for comprehensive data management systems. 

The implementation of these systems will also address two frequently cited problems related to 

consistent and appropriate funding of UVM programs. 

Perhaps the most common complaint we have heard over the last few decades has been that 

UVM budgets have been routinely reduced to fund other maintenance activities that are, in the 

opinion of the utility, more urgent in nature. It appears that whenever reductions in maintenance 

expenses are forthcoming at a utility company, it is often the UVM program that takes the first 

large hit. While it is appropriate to adjust UVM budgets based on a changing workload, UVM 

expenses should not be adjusted to balance budgets or fund other initiatives. The utility should 

perform UVM work when it is appropriate. Unfortunately, without an actual understanding of 

what UVM work needs to be performed, UVM budgets will continue to be a target for funding 

cuts. 

The use of inventory and work management systems will address problems with many current 

ratemaking proceedings. Given the large expense associated with UVM in a non-Performance 

Based Ratemaking (PBR) proceeding, the utility should be required to justify the expenses 

based on facts, rather than anecdotal and historic information. The appropriate governing body 

should base rate recovery on the answers to the first two questions posed in this section: “How 

much vegetation needs to be removed, pruned, or treated in order to prevent outages and 

fires?” and “How much does it cost to complete each unit of work?” 

While we recognize the challenges associated with developing and implementing inventories 

and work management systems, we believe that these systems will yield lower long-term UVM 

costs, and a greater ability to predict and prevent future tree and power line conflicts. 
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IV. FIELD INVESTIGATION 

FIELD REVIEWS RELATED TO THE AUGUST 14TH OUTAGE 

A review of available documentation and our field investigations at AEP and FE suggest that 

four of the line outages were, in fact, caused by conflicts between high voltage transmission 

lines and vegetation. Furthermore, had all these specific trees been pruned or removed prior to 

these outages, the blackout most likely would not have occurred. 

The following contains an overview of our findings of AEP and FE line outages, and identifies 

contributing and/or mitigating factors. We will begin with a brief discussion of conductor sag, and 

follow this up with our investigation protocol and findings. 

Conductor Sag 

A key consideration during the design, construction, and maintenance of transmission lines is 

that of conductor sag. The height of transmission conductors does not remain static once they 

are installed, due in part to such factors as temperature and wind velocity. 

Temperatures typically increase during the summer months, requiring additional power to 

accommodate air conditioning load. As the load increases over transmission lines, each line’s 

temperature increases and the conductors, typically aluminum, expand. The effect of this 

expansion is a lengthening of the conductors, which causes them to sag closer to the ground. 

The presence of wind also influences conductor sag. Wind provides a cooling effect on the 

conductors. This cooling of the conductors reduces the amount of sag that would be 

encountered in comparison to sag on a calm day. 

The following graphic provides an example of how conductor height can vary depending on load 

and wind velocity. 

Field Investigation Protocol 

The vegetation management investigation team consisted of Richard Dearman (TVA), Saeed 

Farrokhpay (FERC), and Stephen Cieslewicz and Robert Novembri of CN Utility Consulting. 

The investigation consisted of a review of prepared responses and documents provided by AEP 

and FE, field visits to one suspect location at AEP and three suspect locations at FE, and 

interviews with AEP and FE contract personnel. Appropriate photographs, GPS readings, 

measurements and calculations were made at each location. 
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General Findings 

Overgrown trees, as opposed to excessive conductor sag beyond design, appear to have been 

the cause of these faults. 

Each of these lines was predisposed to fault under system sag conditions well within normal 

operating parameters. 

• Incremental increases in amperage and temperature caused an incremental sag 

increase on the Stuart – Atlanta (AEP) line causing it to fault and lock out due to contact 

with vegetation. 

• Incremental increases in amperage and temperature increased the sag on the Star – 

South Canton (FE) line causing it to fault and reclose due to contact with vegetation. 

This line tripped three additional times over a period of 11⁄4 hours before locking out. 

• Incremental increases in amperage and temperature increased the sag on the 

Chamberlin – Harding (FE) line causing it to fault and lock out due to contact with 

vegetation. 

• Again, incremental amperage and temperature increases, escalated by the loss of the 

Chamberlin – Harding line caused further incremental sag increases on the Hanna – 

Juniper (FE) and it faulted and locked out due to contact with vegetation. 

We have field evidence of tree contact at three locations. At the fourth location, Hanna – 

Juniper, the tree was removed before we arrived, but the fault was visually (time/date) 

confirmed during the occurrence and pictures of the tree before it was removed support the 

visual observation. We also have a revised calculated fault location, provided by FE, for the Star 

– South Canton line that matches the location of the visually confirmed tree fault. 

Thus, while conductor sag may have contributed in a small way to these events, the direct 

cause of these incidents was overgrown trees. 
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FAULT CHRONOLOGY, OBSERVATIONS AT FIELD SITES AND COMMENTS 

Stuart – Atlanta (345kV) AEP18

14:02:00.0 Line trips and locks out. 

No calculated fault location was provided by AEP for this outage. 

Evidence of tree contact was observed between towers 222 and 223. Conductor height of north 

phase measured 39 feet at tree location and point of contact. Center phase measured 41 feet 

and south phase measured 47 feet. 

Trees and brush were felled on or after August 14th. Debris was left on site and inspected. 

Two ailanthus trees showed evidence of significant fault current damage and were de-barked. 

One measured 2.5” diameter at ground line, and the other measured 6” diameter at ground line.. 

 

18 The Stuart-Beatty 345kV transmission line is jointly owned by Cinergy, Dayton Power & Light (DP&L) and AEP’s 

Ohio operating company Columbus Southern Power. AEP is responsible for conducting patrols, vegetation 

management, maintenance and repair of the Stuart-Beatty 345kV transmission line. The Stuart-Atlanta 345kV circuit 

(a portion of the Stuart-Beatty transmission line) is under the dispatching authority of DP&L and is in DP&L’s control 

area. On occasion, DP&L has performed emergency patrol of the circuit and has referred any problems found to AEP 

for correction. 
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Both trees were estimated to be 30 to 35 feet tall. Other trees in the area showed evidence of 

fault current damage as well. 

The following readings were provided by AEP at the approximate time conductor height 

measurements were taken. 

Time: 10:00 EDT 

Date: 10/22/03 

Temperature Reading: 55.6° 

Wind Speed: N/A 

Conductor Height: 39’ 

Loading: 

Stuart – 950 amps 

Atlanta – N/A 
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Star – South Canton (345kV) FirstEnergy 

14:27:15.880 Line trips and recloses (both ends). 

15:38:47.770 Line trips and recloses (both ends). 

15:41:33.43 Line trips and recloses (both ends). Retrips at South Canton. 

15:42:07.0 Line recloses at South Canton, retrips and locks out. Line already open at Star. 

Calculated Fault Location19 (revised): 20.5% from Star Substation, Span 40375 – 40376 

Inspected conditions at structure 40404 and right-of-way toward 40401 (between 6.7% and 8%). 

No vegetation conflicts observed in this area. Did not review 40399 (9.1%). 

Inspected tree conditions at structure 40376 (20.5%) between towers 40375 and 40376. Trees 

and vegetation were felled on or after August 14th. Debris and tree parts were inspected on site. 

Conductor height measured 44’ 9”. Tree height measured at 30 feet, although we could not 

verify location of the stump, or missing section of tree. Obvious significant fault damage to 

clustered trees. Charred limbs, and de-barked by fault current. 

 

19 The calculated distance from a substation, based on the total distance between substations, represented as a 

percent. 
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Topsoil in the area of trunk was disturbed, discolored and broken up at site. This is indicative of 

a higher magnitude fault or multiple faults. 

Fourteen year-old tree in the middle of the right-of-way was recently removed. 

The following readings were provided by FE at the approximate time conductor height 

measurements were taken. 

Time: 14:14 EDT 

Date: 10/16/03 

Temperature Reading: 47° 

Wind Speed: 1 mph (Wadsworth, OH) 

Conductor Height: 44’ 9” 

Loading: 

Star – 836 amps 

South Canton – N/A 
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Harding – Chamberlin (345kV) FirstEnergy 

15:05:41.0 Line trips and locks out. 

Calculated Fault Location: 11.3% from Chamberlin Substation, Tower 42852 

No evidence of vegetation at calculated fault location (11.3%). See photo below. 

At 17.7%, between towers 42861 and 42860 we inspected vegetation. Trees and brush were 

felled on or after August 14th. Conductor height measured at 46’ 7”, tree height measured at 42’. 

Locust tree showed evidence of fault current damage. Tree damage indicated a lower level of 

fault current. 

Burn marks were observed at 35’ 8” up tree. Portions of the tree had been removed from the 

site making it difficult to determine exact height of contact, implying that the measured height is 

a minimum, and likely 3-4 feet higher than verifiable. 
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Other vegetation along the right-of-way measured between two and five inches in diameter at 

ground line. The following photo depicts a tree located in the right-of-way that was over six 

years old, as indicated by the growth rings. 

The following readings were provided by FE at the approximate time conductor height 

measurements were taken. 

Time: 11:58 EDT 

Date: 10/16/03 

Temperature Reading: 47° 

Wind Speed: 2 mph (Wadsworth, OH) 

Conductor Height: 46’ 7” 

Loading: 

Chamberlin – 405 amps 

Harding – 400 amps 
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Hanna – Juniper (345kV) FirstEnergy 

15:32:03.0 Line trips and locks out. 

Conductor height measured 48’ 9” at fault location. No evidence of tree debris at site. Walnut 

tree stump measured 14” diameter at ground line. 

Subsequent clearing left trees and brush that, in our opinion, could have been removed as 

indicated by the photo below on the left. This photo was taken in the same span as the fault 

occurred. Other trees were pruned and left in the right-of-way as part of a landscaped area as 

indicated by the photo on the right. This photo was taken within one span of the fault. 

The contract foreman who witnessed the event on August 14th was interviewed. He described 

the fault and provided a definitive time and date for the contact incident. 
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Per FE field personnel, the schedule for completing work on this circuit had been advanced by 

one year. In fact, FE’s October 31, 2003 response indicated that this circuit was scheduled for 

regular maintenance in 2003 and work was underway in close proximity to the fault. 

South phase, where contact occurred, is lower than the center phase due to construction 

design. Subsequently, FE provided photographs that clearly indicate that the tree was of 

excessive height. 

The following readings were provided by FE at the approximate time conductor height 

measurements were taken. 

Time: 09:31 EDT 

Date: 10/16/03 

Temperature Reading: 44° 

Wind Speed: 3 mph (Wadsworth, OH) 

Conductor Height: 48’ 9” 

Loading: 

Hanna – 900 amps 

Juniper – 970 amps 
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Columbus – Bedford (345kV) Cinergy 

12:08:40.0 Line trips and locks out. 

18:23:00.0 Line returned to service. 

We also performed an initial review of a transmission fault experienced on the Cinergy system 

on August 14th in Indiana. While it does not appear that the fault was connected to the blackout, 

this situation does provide a very good example of the obstacles placed in front of utilities that 

are attempting to manage vegetation near overhead power lines. 

Based on discussions with Cinergy, this transmission line fault occurred as a result of tree 

contact in one span of the Columbus – Bedford circuit. The photo below was taken prior to 

August 14th. 

Apparently work on this span had been halted various times by the owner of the property. The 

owner of the property had severely limited the ability to achieve necessary clearances and to 

apply herbicides to control future growth. While Cinergy does, in fact, have documented rights to 

perform this work (documented easement), this landowner has successfully halted work from 

proceeding on several occasions. This included the homeowner obtaining a court-granted 

temporary injunction halting work by Cinergy. Note: the required work was finally completed on 

October 9, 2003 as depicted in the photo below. 
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We bring this up to illustrate that there are many hurdles every utility company must face when 

trying to maintain lines clear of vegetation. In this particular case, it was a landowner that halted 

work. In other cases we are aware of, it can be local, state, or even federal agencies that hinder 

progress. See Appendix ‘D’ for a detailed description of this incident. 
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V. UVM PROGRAM ASSESSMENTS 

Introduction 

This section of the report contains the results of our UVM program assessments for AEP, FE, 

and Cinergy. We will begin with a brief description of the methods we used to perform these 

assessments, followed by general commentary and recommendations regarding our 

assessment of all three UVM programs. This will be followed by utility-specific findings and 

recommendations. 

Method of Assessments 

This section of the report covers all items related to the following original task: 

Collect and analyze information and data regarding transmission right-of-way vegetation 

management practices of three electric utility companies in order to assess the strengths 

and weaknesses of each company’s vegetation management program. The utilities 

included AEP, FE, and Cinergy. 

In order to satisfy this objective, a review of each utility’s vegetation management program was 

completed to assess each company’s effectiveness and to provide comparisons to industry 

benchmarks. These assessments included performing the following key tasks: 

1. Conducted field investigations (AEP and FE only) 

2. Evaluated responses to prepared initial data requests 

3. Conducted interviews with key personnel 

4. Evaluated responses to follow-up data requests and supplemental inquiries 

In addition, the following documents, manuals, and procedures were reviewed for each utility: 

Tariff Process Work Histories 

Easements Work Processes 

Permits Budgets 

Ordinances Outage Reporting 

UVM Program Standards Compatible Tree Lists 

Maintenance Standards Ohio PUC Outage Filings 

Program Structure Ground Patrols 

Contracts Aerial Patrols 

Computer Systems Commission Requirements (See Appendix ‘H’) 

The resulting information was then compared to UVM industry practices and programs in both 

the US and Canada20. 

General Commentary and Recommendations 

Our general findings are that all three UVM programs are consistent with what we would 

currently expect to see at other utility companies in this industry. There are certainly differences 

in the strengths and weaknesses of each program, but in general, we uncovered no evidence to 

suggest that any of these UVM operations could be considered sub-standard compared to the 

 

20 Based on our comprehensive and industry-reflective UVM benchmarking study. 
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rest of the industry. All three utilities have an adequate UVM program in place that reasonably 

satisfies the limited requirements set forth in current industry requirements and standards. 

However and as illustrated in various sections of this report, we do not believe that the “current” 

industry requirements and standards are adequate to require utility companies to achieve the 

level of UVM necessary to improve reliability by reducing tree-caused transmission outages. If 

compared to the “best management practices” outlined in Section VII of this report, all three 

utilities would have sub-standard programs21. 

While all three utilities have programs consistent with what is expected of them based on the 

status quo, and regardless of whether new laws, regulations, or requirements are promulgated, 

we strongly encourage each of the three utilities (and all others) to consider the following 

recommendations: 

1. Consider adopting the Best Management Practices as defined in this document. 

2. Consider adopting the utility-specific recommendations found in the following sections. 

3. Work with appropriate officials and the public to remove obstacles to completing the 

required work in a timely manner. 

4. Consider performing routine UVM program assessments. 

5. Work toward developing a Best-In-Class UVM program. 

We also recommend that each of the utility companies consider direct involvement with The 

National Arbor Day Foundation’s Tree Line USA program, and the EPA’s Pesticide 

Environmental Stewardship Program (PESP)22. While these voluntary programs do not 

necessarily ensure any improvements in preventing outages, they both require that utility 

company members focus on correctly managing transmission ROWs and performing the work in 

a manner that is consistent with industry accepted practices. We believe that Tree Line USA 

and PESP participation are baseline indicators of a competent UVM program. 

In the following section, we provide detailed information, analysis, and specific 

recommendations for each of the three utility UVM programs. While we are confident of these 

findings, it is important to note that there are hundreds of processes and procedures that could 

be evaluated for each of these UVM programs. We have tried to focus on the larger issues for 

each of the utilities. We have provided a comprehensive side-by-side comparison between 

these utilities, and the UVM industry, at the end of this section. 

 

21 If the same standard was applied to the rest of the industry, there would be only a handful of utilities in the industry 

that could suggest they were themselves above sub-standard. 22 Detailed information regarding these programs can be found at the following links: 

http://www.epa.gov/oppbppd1/PESP/about.htm

http://www.arborday.org/programs/treelineusa.html
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AMERICAN ELECTRIC POWER (AEP) 

Following the general information regarding AEP and its UVM activities, this section provides a 

brief discussion of key program elements, and then our findings and recommendations for 

AEP’s UVM program. 

Utility Description 

AEP is one of the largest electric utility companies in North America and currently serves 

approximately 4.9 million electric customers in Arkansas, Indiana, Kentucky, Louisiana, 

Michigan, Ohio, Oklahoma, Tennessee, Texas, Virginia, and West Virginia. 

Description of Transmission UVM Program 

AEP manages vegetation along approximately 38,000 miles of transmission line within its entire 

service territory. This includes managing approximately 103,812 acres of vegetation, and 

437,400 individual trees adjacent to transmission facilities and lines. 

Involvement with the August 14th Blackout 

AEP experienced a tree-related fault on the Stuart – Atlanta 345kv line on August 14th at 14:02 

hours. 

 

Discussion: This incident occurred as a result of overgrown trees and as such, could be 

classified as an “avoidable” outage. (See discussion below on “service reliability”) 

Key Program Elements 

Organizational Structure

AEP’s UVM program is centralized with a full and part time in-house staff reporting to a System 

Forester. These employees oversee the work of 43 contracted transmission UVM crews. 

Discussion: AEP’s organizational structure is consistent with what we would expect to 

see at an equivalent utility. 

Current System Conditions

AEP reported that less than 2% of trees on their system are either potentially in contact with 

electric transmission lines at any given moment, or in contact with the lines at the time of 

pruning. 

Discussion: Industry benchmarking indicates that the average for either situation is 

approximately 1% or less of the total population of trees adjacent to transmission lines. 

AEP’s claim is within the range we would consider normal for transmission lines. 

Service Reliability

AEP reported that 25% of historic tree-related outages could be considered “avoidable23” 

whereas the remainder would be classified as “unavoidable24.” This is consistent with industry 

benchmarks. 

 

23 Typically attributed to tree growth or hazardous trees that should have been identified as potential hazards. 24 Typically attributed to trees, or portions thereof, outside of the normal clearing zone that fall or are blown into high 

voltage conductors. 
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Discussion: The majority of utilities track and differentiate between “avoidable” and “unavoidable” tree-related outages. These differentiations allow a utility to track, and 

hopefully reduce those outages that could be prevented by routine work. Currently, 

approximately three fourths of tree related outages in the UVM industry are categorized 

as unavoidable (could not have been avoided given current requirements and 

standards). The remaining 25% could conceivably have been avoided had required UVM 

work been completed prior to the outage. (Note: the use of consistent definitions of 

“avoidable” and “unavoidable”, and the rigor of their application, is discussed in a later 

section) 

Contracting

AEP competitively contracts out the following UVM activities to qualified vendors: Pruning & 

removal, ROW clearing, Tree Growth Regulators (TGR), Herbicide application, Pre-inspection, 

and clerical support. AEP relies primarily on Time & Material (T&M) contracts (99%) but does 

also utilize a few unit price and lump sum contracts. The typical duration of the T&M contracts is 

five years. AEP currently has five different vendors working under these contracts. 

Discussion: AEP’s contracting practices are consistent with the industry. 

Work Techniques

AEP reported that it complies with industry-accepted pruning standards found in ANSI A30025, 

and other often-referenced publications. AEP stated that 100% of lines are managed utilizing 

appropriate Integrated Vegetation Management (IVM) techniques. 

Discussion: AEP’s stated work techniques and referenced standards are consistent 

with the industry 

Historic Budgeting

The following are AEP’s “budget” versus “actual” expenses for transmission UVM program 

activities: 

Year Budget Actual

1998 $ $ (REDACTED) 

1999 

2000 

2001 

2002 

2003 

Discussion: While there are minor anomalies between budget and actual, they are not 

significant enough to cause us any concern. 

 

25 ANSI A300 is the industry consensus standard which describes proper pruning near power lines.
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Historic Completed Work

AEP provided the following summary of completed Transmission UVM work by year: 

Year Trees Pruned Trees Removed Acres Mowed Acres Treated

1999 14,014 53,611 576.5 2,478.86 

2000 15,759 42,250 882.94 2,962.86 

2001 9,348 30,205 821.73 3,097.72 

2002 10,723 21,591 722.59 4,335.67 

Projected 03 15,000 23,000 1,000 4,450 

Discussion: These statistics illustrate common and expected trends in a transmission 

UVM program. For example, tree removals are consistently higher than trees pruned, 

which indicates a correct focus of resources. Also, a consistent increase in the number 

of acres treated typically indicates that more of the system is being managed proactively, 

as opposed to reactively. 

Cycles

AEP states that their transmission UVM program is on a cycle that does vary upon the types of 

transmission facilities and locations. AEP’s stated cycles for performing UVM work are as 

follows: 

Urban/Suburban – 2-4 yrs 

Rural – 6-8 yrs 

Discussion: The majority of transmission UVM programs have varying cycles that are 

consistent with those claimed by AEP. 

Patrol Methods and Frequency 

AEP indicates they patrol their lines “generally, once a year” and employ an outside helicopter 

company to provide the service. We could not determine, based on data request responses, 

exactly how many ground patrols, if any, occur on a regular basis. However, it important to note 

that an aerial patrol was performed on the Stuart – Atlanta circuit that experienced an outage on 

August 14th: 

Stuart – Atlanta: An aerial patrol conducted on June 25, 2003 resulted in no vegetation related 

problems being observed. 

Discussion: There seems to be a wide gap in the industry regarding the frequency and 

method of patrolling transmission lines. Some utilities rely, as appears to be the case 

with AEP, on annual aerial patrols, while others may rely more heavily on ground patrols. 

In general, a combination of both methods seems to be the norm. In addition, routine 

inspections by the utility are complemented by a great deal of patrolling and observation 

during pre-inspection of routine UVM work. 

Influences on Work Progress

AEP states that the following laws and regulations apply to their UVM operations: 

NESC Rule 218 

State Highway Requirements 

Local Street Tree Ordinances 

Other Local Ordinances 
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AEP states it does not work under mandatory clearance requirements, but that its work is 

influenced or hindered by local ordinances. 

We reviewed easement documents for the location of the outage on the Stuart – Atlanta 345kV 

line and found no restrictions that would have precluded the required work from being 

performed prior to the outage. 

Sag and Sway

A review of AEP’s Goals, Procedures & Guidelines for T&D Line Clearance Operations and 

Contract Specification, revealed no reference to consideration for sag and sway during pruning 

and removal operations. 

Discussion: Unfortunately, most utilities do not provide specific direction to the UVM 

workers regarding how to take conductor sag and sway into consideration when deciding 

site-specific clearances to be achieved during routine work. This is an area that warrants 

attention, and improvement, by the industry. 

Engineering Assumptions

A high level review of AEP’s engineering assumptions regarding line ratings, line sag, and line 

clearances was performed (See Appendix ‘I’). The following areas of concern were noted during 

the review. 

1. The basis for the assumed ambient temperature used for line ratings is unclear. 

Findings and Recommendations 

AEP’s UVM programs and program attributes are consistent with what we would expect to find 

at a similarly sized utility, working under the same requirements and conditions. It is not a bestin-class program, nor would we consider it to be substandard. There are both strengths and 

weaknesses worth mentioning. 

AEP seems to have a competent UVM organization and strong support from upper 

management. AEP also maintains a visible and positive presence within the UVM industry. They 

have a history of active industry involvement and have contributed in many ways to the progress 

of this industry. In fact, several AEP UVM employees (past and present) have been recognized 

by the industry for their specific contributions. 

While AEP has not obtained The National Arbor Day Foundation’s (NADF) Tree Line USA26

designation (see #1 below), they are the only one of the three utilities to be an active member of 

EPA’s Pesticide Environmental Stewardship Program27 (PESP). While this program does not 

ensure any improvements in preventing outages, it does require that utility company members 

focus on correctly managing transmission ROWs and performing the work in compliance with 

industry accepted practices. As with the NADF Tree Line USA designation, we believe that 

PESP participation is a baseline indicator of a competent UVM program. 

While we did not uncover any major negative revelations during the review of AEP’s 

transmission UVM program, we will provide the following observations and recommendations: 

 

26 http://www.arborday.org/programs/treelineusa.html 27 http://www.epa.gov/oppbppd1/PESP/about.htm
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1. AEP should consider working toward obtaining the NADF’s Tree Line USA designation. In 

addition to helping the utility stay focused on important activities such as worker training, 

public education, and the use of proper tools and techniques, this designation acts as a 

baseline measurement of overall program efficacy. In other words, we would expect that any 

utility company that wishes to have a “Best-in-Class” UVM program would first obtain the 

Tree Line USA designation. This is a basic measure of general UVM competence and we 

encourage all utilities to achieve this designation. 

2. While annual aerial patrols may be consistent with industry standards, given their obvious 

limitations28, we believe that these should be validated through routine ground patrols. AEP 

needs to review and modify the frequency and methods of patrolling for the identification of 

vegetation-related problems. Based on the following, it is apparent that the current patrolling 

methods and frequency were not adequate to prevent the August 14th outage on the Stuart – 

Atlanta 345kV line. 

A patrol completed on the Stuart – Atlanta line on June 25, 2003 by a helicopter service and 

by using an AEP Transmission Line Mechanic, identified no vegetation related problems. 

Fifty days after this aerial patrol, August 14th, the outage occurred on the Stuart – Atlanta 

345kV line from tree/conductor contact. 

It appears that the tree(s) that caused the August 14 outage should have been identified 

during the preceding aerial patrol. If they had been, this specific outage should not have 

occurred. While helicopter patrols are both necessary and efficient in most cases, they do 

have inherent problems when it comes to identifying potential vegetation clearance issues 

because you cannot consistently and accurately determine the distance between vegetation 

and conductors from the air. In cases where there is any question regarding clearances 

observed from the air, we recommend a follow-up ground patrol. 

3. While the AEP Transmission Operations department does perform monthly checks of 

transmission outage reporting statistics, AEP should review current “tree related outage” 

reporting procedures. Several responses to our data requests raised concerns about AEP’s 

focus on outage reporting. AEP reported eleven tree-related transmission outages in 2002 

on transmission circuits rated 138kV and below. Nine of these outages were reported as 

being caused by trees “inside” of the right-of-way and two were reported as being caused by 

trees “outside” the right-of-way. Without additional information on the specifics of these 

events, we can only conclude that the majority of these outages should have been classified 

as “avoidable”, versus “unavoidable.” As previously mentioned, AEP claims that 75% of 

outages in 2002 were “unavoidable.” It is possible however that there could be explanations 

for this apparent anomaly, and suggest it be looked at in more detail. 

Other reasons for suggesting a review of “tree-related” outage reporting procedures has to 

do with an apparent problem in the industry that is not unique to AEP. Benchmarking 

indicates that there may be a problem with outage reporting accuracy at many other utilities 

in North America. In fact, 50% of reporting utilities in our benchmarking study suggested that 

there needs to be improvement in this area. Statistics on tree related outages (for both 

transmission and distribution) may be inflated or under-stated due to inaccurate reporting 

procedures. We recommend that all utilities validate current procedures and protocols and 

the accuracy of their reporting. 

 

28 Three of the four lines whose tree contact led to the cascading blackout were aerially inspected in the Spring of 

2003. 
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4. AEP should initiate a program that identifies and prioritizes transmission ROWs that require 

re-claiming. Documented easement rights should be fully exercised where possible, and it 

should be the objective of AEP (and all utilities) to prevent ROWs from becoming 

unmanaged and overgrown. The common thread between the August 14th tree-related 

outages on AEP, FE, and Cinergy’s systems was that none of these ROW locations had 

been fully managed in a manner consistent with the documented rights to do the work. A 

ROW that has been consistently managed utilizing proper IVM techniques and Wire Zone -

Border Zone concepts significantly reduces the likelihood of future tree and power line 

conflicts. 

5. Finally, given our general finding here that the status quo industry practices are not 

adequate, we recommend that AEP consider adopting all of the general recommendations 

referenced in this document. AEP should work toward incorporating all Best Management 

Practices into their program and work with appropriate parties, including utility regulators, to 

remove obstacles to completing required work. 
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FIRSTENERGY (FE) 

Following the general information regarding FE and its UVM activities, this section provides a 

brief discussion of key program elements, and then our findings and recommendations for FE’s 

UVM program. 

Utility Description 

FirstEnergy Corp. is a holding company made up of seven electric utility operating companies, 

Ohio Edison, The Illuminating Co., Toledo Edison, Penn Power, Penelec, Met-Ed, and Jersey 

Central Power and Light. It has a service territory of 36,100 square miles and serves 4.3 million 

customers. It operates in the states of Ohio, Pennsylvania and New Jersey. 

Description of Transmission UVM Program 

FE manages approximately 283,445 trees and 56,405 acres along its 35,796 miles of 

transmission line, rated at 69kV and above. 

Involvement with the August 14th Blackout 

As indicated in our Initial Report, there were three transmission outages on the FE system that 

contributed to the degradation of the system and subsequent blackout. Tree/conductor contact 

occurred on the Star – South Canton 345kV line, the Harding – Chamberlin 345kV line, and the 

Hanna – Juniper 345kV line. A more detailed discussion about these incidents is contained in 

the Field Investigation portion of this report. 

Key Program Elements 

Organizational Structure

FE’s UVM program is structured as a de-centralized29 organization with a full-time staff of 25 inhouse employees and 6 contract foresters. Field staff is distributed throughout the FE service 

territory and report up through various operational organizations. The program is overseen by a 

System Forester, or equivalent, and corporate UVM staff. These employees oversee the work of 

39 contract transmission crews and a larger number of distribution crews. The reporting 

structure is as follows for both the Corporate and Regional organizations: 

Corporate Positions Regional Positions

Vice President, Energy Delivery Region President 

Director, T&D Support Director, Regional Operations 

Supervisor, Distribution Forestry Forestry Manager, Regional Operations 

Distribution Specialist, Distribution Forestry Distribution Specialist, Regional Operations 

Discussion: FE’s organizational structure, although not typical in the industry, is 

consistent with what we would expect to see at a corporation with various operating 

companies. While we would prefer to see all UVM activities at a company to be 

centralized, there may be valid reasons at FE for this particular structure. Because FE is 

structured in this way, there may be inconsistencies in operational procedures linked to 

either its organizational structure, or the process of integrating acquired entities. (See FE 

Findings and Recommendations) 

. 

 

29 More than one department has responsibilities for the UVM program. 
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Current System Conditions

FE indicates that, to the company’s knowledge, there are currently no trees in contact with 

electric transmission lines. No response was provided regarding contact with transmission lines 

at the time of pruning. (Note: No further inquiry was made as to the basis of the “to our 

knowledge” response.) 

Discussion: Industry benchmarking indicates that the average for either situation is 

approximately 1% or less of the total population of trees adjacent to transmission lines. 

Service Reliability

The following provides historical information regarding “avoidable” versus “unavoidable” outages 

on the FE system. 

Year Avoidable Unavoidable

2000 75% 25% 

2001 57% 43% 

2002 25% 75% 

Discussion: As previously noted, the majority of utilities track and differentiate between 

“avoidable” and “un-avoidable” tree-related outages. These differentiations in theory 

allow a utility to track, and hopefully reduce those outages that could be prevented by 

routine work. Currently, approximately three fourths of tree related outages in the UVM 

industry are categorized by the reporting utilities as unavoidable (could not have been 

avoided given current requirements and standards, and typically attributed to trees 

outside of the standard clearance zones). The remaining 25% could conceivably have 

been avoided had required UVM work been completed prior to the outage. The current 

ratio at FE is consistent with the industry average. 

Note: We have no definitive explanation for the significant shift from avoidable to 

unavoidable outages between 2000 and 2002 as reported by FE. In general, this could 

be consistent with a change in the accuracy of outage reporting and/or an overall 

improvement in program efficacy. Another possible explanation could be related to the 

small number of outages that are reported on transmission lines annually. A small shift in 

outages from avoidable to unavoidable can cause a significant swing in these 

percentages. 

Contracting

FE competitively contracts out the following UVM activities to qualified vendors: Pruning and 

removal, right-of-way clearing, inventory work, pole clearing, R&D, clerical support, and 

herbicide and tree growth regulator applications. FE utilizes a combination of Time and Material 

(T&M) and Lump Sum contracts that are competitively awarded. The typical duration of these 

contracts is one year with some multi-year contracts being awarded. FE currently has eight 

different vendors working under these contracts. 

Discussion: FE’s contracting practices are consistent with the industry. 

Work Techniques

FE reported that it complies with industry-accepted pruning standards found in ANSI A300, and 

other often-referenced publications. FE stated that 100% of lines are managed utilizing 

appropriate Integrated Vegetation Management (IVM) techniques. 
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Discussion: FE’s stated work techniques and referenced standards are consistent with 

the industry. 

Historic Budget

The following provides a comparison between FE’s “budget” versus “actual” expenses for 

transmission UVM program activities: 

Year Budget Actual

2000 $ $ (REDACTED) 

2001 

2002 

2003 

Discussion: There are no significant deviations in expenditures that would cause us to 

be concerned. 

Historic Completed Work

FE tracks the number of trees pruned or removed by year and they track the acres treated and 

mowed per year on their transmission system: 

Year Trees Pruned Trees Removed Acres Mowed Acres Treated

2000 19,266 32,362 108.08 2,376 

2001 20,092 36,075 564.82 2,492 

2002 19,254 36,641 846.90 2,097 

Projected 03 17,748 25,736 274.57 2,098 

Discussion: These statistics illustrate common and expected trends in a transmission 

UVM program. For example, tree removals are consistently higher than trees pruned, 

which indicates a correct focus of resources. Also, if a company is employing IVM 

techniques, and has its system under control, it is appropriate to see a higher number of 

acres “treated” as opposed to “mowed”. We have no concern related to FE’s stated 

numbers. 

Cycles

FE states that their transmission UVM program is on a five-year cycle. In addition, they noted 

that: “All transmission lines are on a five-year cycle, although our practice recognizes that for 

some locations, more frequent spot control is required, such as urban areas or where conditions 

limit tree to conductor clearances (i.e., through easement restrictions).” 

Discussion: This response is consistent with what we would expect and do not have 

any concerns. 

Patrol Methods and Frequency

FE reported that it uses both aerial and ground patrols. Although FE indicates they are on a fiveyear UVM cycle, patrols of their transmission system appear to be performed on a more 

frequent basis. For example, frequent aerial patrols were performed on the three circuits that 

experienced outages on August 14th. The dates of those patrols are as follows: 
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Harding – Chamberlin: June 2001, November 2001, July 2002, November 2002 and April 

2003. 

Hanna – Juniper: May 2001, October 2001, June 2002, October 2002 and April 2003. 

South Canton – Star: July 2001, December 2001, April 2002, October 2002 and April 2003. 

In a review of the most recent inspection reports from these aerial patrols, nothing significant 

regarding vegetation clearances was noted for the three locations where outages occurred. 

Discussion: It appears that the trees that caused the outages on August 14th should 

have been identified during one or more of the preceding aerial patrols. If they had been, 

these specific outages should not have occurred. While helicopter patrols are both 

necessary and efficient in most cases, they do have inherent problems when it comes to 

identifying potential vegetation clearance issues. In certain cases you cannot accurately 

determine the actual distance between vegetation and conductors from the air. In cases 

where there is any question regarding clearances observed from the air, we recommend 

a follow-up ground patrol be initiated. 

Influences on Work Progress

FE did not provide a response regarding what laws and regulations apply to their UVM work. 

However, we reviewed easement documents for the location of the outages on the Harding – 

Chamberlin, Hanna – Juniper, and the South Canton – Star 345kV lines and found no 

restrictions that would have precluded the required work from being performed prior to the 

outages. 

Sag and Sway

In a review of FE’s Vegetation Management Specification (contract and work specifications) we 

were unable to find any reference to consideration for sag and sway during pruning and removal 

operations. 

Discussion: Unfortunately, most utilities do not provide specific direction to the UVM 

workers regarding how to take conductor sag and sway into consideration when deciding 

site-specific clearances to be achieved during routine work. This is an area that warrants 

attention, and improvement, by the industry and FE. We have addressed this issue in 

our general recommendations 

Engineering Assumptions

A high level review of FE’s engineering assumptions regarding line ratings, line sag, and line 

clearances was performed (See Appendix ‘I’). The following areas of concern were noted during 

the review. 

1. FE’s assumed wind speed of 6 feet per second (fps) is significantly higher than the 

typical industry values of 2 fps for both normal and emergency ratings. Although the 

industry is starting to consider using 4 fps wind speed under certain conditions, FE’s 6 

fps is still significantly greater. 

2. The temperature assumptions used in line ratings are unclear. 
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Findings and Recommendations 

FE’s UVM program, and program attributes are consistent with what we would expect to find at 

a similarly sized utility. It is not a best-in-class program, nor would we consider it to be 

substandard. There are both strengths and weaknesses worth mentioning. 

Out of the three utilities we reviewed, only FirstEnergy has obtained the Tree Line USA30

certification from The National Arbor Day Foundation (NADF). FE has actually received this 

designation for each of the last five years. While the Tree Line USA designation does nothing to 

indicate how effective a utility is in reducing tree related outages, it is a basic measure of the 

utility’s commitment to various important UVM functions (public education, worker training, and 

quality work). Our experience has shown that utilities that have achieved this designation are 

typically more inclined to be working toward a best-in-class status. 

However, FE does have issues it should address if it intends to ever achieve a best-in-class 

status. One issue that FE has been working to resolve is a by-product of trying to standardize 

their UVM programs across several company boundaries. FE is made up of several merged 

companies and each of them has a different history regarding UVM programs. Parts of FE have 

historically had well managed UVM programs, whereas other parts of FE did not. In other 

words, some areas are in good shape, while others are not. We believe that without significant 

efforts directed specifically to this outcome, it may take a considerable period of time before FE 

can state their system is relatively uniform regarding vegetation conditions along transmission 

ROWs. FE must work diligently and devote whatever resources are necessary to bring areas of 

the system, which are currently lagging, up to the highest standards as quickly as possible. 

We also offer the following observations and recommendations: 

1. FE should review its practices related to patrolling, pre-identification, and assignment of 

work. We make this recommendation based on our investigation of the outage on the Hanna 

– Juniper 345kV line. As mentioned in our initial report, several trees in the vicinity of the 

outage should have been identified and removed during the routine work that preceded this 

outage. When we interviewed an FE employee about these trees we were told that the 

sequence of pre-inspecting and assigning work is as follows: After the circuit is assigned, 

the contractor goes out and completes what they think is required. After the work is 

completed, FE UVM personnel may perform a post audit and require the contractor to return 

to the site to do any additionally identified work. Following that, an FE land agent may also 

inspect the site to determine if the work fully complies with the documented easement rights. 

If it does not, the contractor once again returns to the site. If this is an accurate description 

of how FE pre-identifies and assigns work, this is an extremely ineffective process. The full 

extent of the required work should be identified before being assigned to the crews. Crews 

should only return to the same location if they have not complied with the original 

prescription for the work. 

2. FE should initiate a program that identifies and prioritizes transmission ROWs that require 

re-claiming. Documented easement rights should be fully exercised where possible, and it 

should be the objective of FE (and all utilities) to prevent ROWs from becoming unmanaged. 

The common thread between the August 14th tree-related outages on AEP, FE, and 

Cinergy’s systems was that none of these locations was managed in a manner consistent 

with the documented rights to do the work. Simply put, a ROW that has been consistently 

 

30 http://www.arborday.org/programs/treelineusa.html
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managed utilizing proper IVM techniques and Wire Zone - Border Zone concepts 

significantly reduces the likelihood of future tree and power line conflicts.

3. We recommend that FE consider participating in the EPA’s Pesticide Environmental 

Stewardship Program31 (PESP). While this program does not necessarily ensure any 

improvements in preventing outages, it does require that utility company members focus on 

correctly managing transmission ROWs and performing the job correctly. As with the NADF 

Tree Line USA designation, we believe that PESP participation is a baseline indicator of a 

competent UVM program. 

4. Finally, we recommend that FE consider adopting all of the general recommendations 

referenced in this document. FE should work toward incorporating all Best Management 

Practices into their program, and work with appropriate parties to remove obstacles to 

completing required work. Based on recent press reports, we understand that FE has 

recently commissioned a study of their UVM program. We believe this to be a positive step 

forward and would encourage FE to consider commissioning this type of review every 3-5 

years. 

 

31 http://www.epa.gov/oppbppd1/PESP/about.htm
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CINERGY 

Following the general information regarding Cinergy and its UVM activities, this section provides 

a brief discussion of key program elements, and then our findings and recommendations for 

Cinergy’s UVM program. 

Utility Description 

Cinergy Corporation was created in 1994 as a result of a merger between Cincinnati Gas & 

Electric and PSI Energy. Cinergy currently serves approximately 1.5 million electric customers 

in Ohio, Indiana, and Kentucky through their regulated subsidiaries. These include Cincinnati 

Gas & Electric Company (Cinergy/CG&E), Union Light Heat and Power (Cinergy/ULH&P), and 

PSI Energy (Cinergy /PSI). 

Description of Transmission UVM Program 

Cinergy manages vegetation along approximately 8,340 miles of transmission lines rated at 

69kV and above. Cinergy does not track the total number of trees managed, but does indicate 

that they manage approximately 91,000 acres of vegetation along these ROWs. 

Involvement with the August 14th Blackout 

A tree-related outage did occur on Cinergy’s system in the hours before the blackout, which 

required extensive attention from Cinergy and MISO system operators. Although this outage 

had no electrical consequence for the subsequent Northeast Blackout, it did lead the Task 

Force to include Cinergy in its UVM review. The outage occurred on the Columbus – Bedford 

345kV line which is located in Indiana and was attributed to trees contacting the conductors. 

As we stated in our Initial Report, the Cinergy incident provides a graphic illustration of what can 

happen when utility companies are stopped by landowners or land use authorities from 

performing required UVM work. In Cinergy’s case, it was an individual “refusal,” as opposed to 

an agency, that stopped Cinergy from fully exercising their rights to perform the work. A 

comprehensive history of this incident can be found in Appendix ‘D’. 

Key Program Elements 

Organizational Structure

Cinergy’s UVM program is centralized with a full-time staff of 15 utility employees reporting to a 

System Forester. These employees oversee the work of 39 contracted transmission UVM crews 

working in Ohio, Indiana, and Kentucky. 

Discussion: Cinergy’s organizational structure is consistent with what we would expect 

to see at an equivalent utility. 

Current System Conditions

Cinergy does not track the number of trees that are potentially in contact with electric 

transmission lines at any given moment, or in contact with the lines at the time of pruning. While 

not tracked, Cinergy believes this number to be minimal. 

Discussion: Industry benchmarking indicates that the average for either situation is 

approximately 1% or less of the total population of trees adjacent to transmission lines. 
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Service Reliability

Cinergy did not provide historic information on “avoidable” versus “unavoidable” tree-related 

outages. 

Discussion: The majority of utilities track and differentiate between “avoidable” and “unavoidable” tree related outages. These differentiations allow a utility to track, and 

hopefully reduce those outages that could be prevented by routine work. Currently, 

approximately three fourths of tree related outages in the UVM industry are categorized 

as unavoidable (could not have been avoided if the system was maintained to current 

requirements and standards). The remaining 25% could conceivably have been avoided 

had required UVM work been completed prior to the outage. Cinergy did not provide 

these numbers so we cannot make a comparison to the industry. 

Contracting

Cinergy competitively contracts out the following UVM activities to qualified vendors: Pruning 

and removal, right-of-way clearing, and herbicide and tree growth regulator applications. 

Cinergy utilizes a combination of Time and Material (T&M) and Unit Price contracts that are 

competitively awarded. The typical duration of these contracts is three years, with an option to 

extend. Cinergy currently has five different vendors working under these contracts. 

Discussion: Cinergy’s contracting practices are consistent with the industry. 

Work Techniques

Cinergy reported that it complies with industry-accepted pruning standards found in ANSI A300, 

and other often-referenced publications. Cinergy stated that 70% of lines are managed utilizing 

appropriate Integrated Vegetation Management (IVM) techniques. The remaining 30% of 

locations do not require extensive IVM techniques, or are unsuitable for their application. 

Discussion: Cinergy’s work techniques are consistent with the industry 

Historic Budgeting

The following provides a comparison between Cinergy’s “budget” versus “actual” expenses for 

transmission UVM program activities: 

Year Budget Actual

1998 $ $ (REDACTED) 

1999 

2000 

2001 

2002 

2003 

Discussion: There are no anomalies in these self-reported numbers that would indicate 

concern on our part. In fact, they appear to suggest that Cinergy routinely increases 

required expenses for UVM work, regardless of projected budgets. 

Historic Completed Work

Cinergy does not track the number of trees pruned or removed by year. Cinergy does however 

track the acres treated and mowed per year. 
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Discussion: The majority of utility companies comprehensively track historic completed 

work. This tracking typically involves statistics on trees pruned or removed, acres treated 

or mowed, or variations based on miles per line. We consider the development and 

tracking of appropriate indices to be a critical part of any UVM program. Based on 

Cinergy’s responses, we are not convinced that they currently track historic work in a 

manner consistent with industry practices. 

Cycles

Cinergy states that their transmission UVM program is “generally cyclic” in nature and these 

cycles vary upon the types of transmission facilities and locations. Cinergy’s stated cycles for 

performing UVM work are as follows: 

Urban/Suburban – As needed 

Rural – As needed 

Side trim – 4-5 years 

Mowing – As needed 

Herbicide – 4-5 years 

Discussion: The majority of transmission UVM programs have varying cycles. Cinergy’s 

response “as needed” does not provide adequate information to make comparisons with 

other utilities. 

Patrol Methods and Frequency

Cinergy documents indicate that they patrol their transmission lines two or more times annually 

utilizing a combination of aerial and ground patrols. 

Discussion: Cinergy obviously patrols their lines on a more frequent basis than the 

majority of utility companies. Given that the “key” to preventing tree related outages is 

being able to identify and correct problems in a timely manner, we would have to say 

that Cinergy is doing a good job with respect to frequency of patrols. 

Influences on Work Progress

Cinergy states that the following laws and regulations apply to their UVM operations: 

NESC Rule 218 

USFS other Federal requirements 

Public Utility Commission 

State Highway Requirements 

Local Street Tree Ordinances 

Other Local Ordinances 

Cinergy states it does not work under mandatory clearance requirements, and that there are no 

agency-related restrictions that hinder their Transmission UVM activities. 

Discussion: As discussed in earlier sections of this report, most utility companies do 

indeed encounter many restrictions that impact the ability to perform required work. 

Cinergy apparently does not face this ubiquitous obstacle. 
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Sag and Sway

Cinergy provided the following general statement regarding sag and sway and how it is 

communicated to their contractors: “In planning trim heights and work activities (for safety) the 

“rule of thumb” assumption is that the conductor can sag to a height of 20’-25’ above ground 

level at peak conditions.” 

Discussion: In a review of Cinergy’s contract Work Specification we found no reference 

or instructions to their contractors regarding sag and sway. As we have stated in various 

places in this report, we believe that this is an area that needs to be improved. Utility 

companies must develop and communicate better instructions for UVM workers 

regarding how sag and sway should be incorporated into clearance specifications. 

Engineering Assumptions

A high level review of Cinergy’s engineering assumptions regarding line ratings, line sag, and 

line clearances was performed (See Appendix ‘I’). The following areas of concern were noted 

during the review. 

1. The basis for the assumed ambient temperature used for line ratings at Cinergy is 

unclear. 

2. There does not appear to be consideration of creep during conductor sagging. 

3. It is unclear whether or not Cinergy checks conductor sag during routine inspections. 

Findings and Recommendations 

Cinergy’s UVM program, and program attributes are consistent with what we would expect to 

find at a similarly sized utility, working under the same requirements and conditions. It is not a 

best-in-class program, nor would we consider it to be substandard. There are both strengths 

and weaknesses worth mentioning. (See general recommendations regarding our conclusion 

that the current industry standard is inadequate for the prevention of transmission outages due 

to tree contact.) 

Cinergy seems to have a competent UVM organization and strong support from upper 

management. Based on our review of documentation, data responses, and discussions with 

Cinergy employees at all levels, we believe they understand the importance of this activity and 

are willing to continually improve their program. 

While we did not uncover any major negative revelations during the review of Cinergy’s 

transmission UVM program, we will provide the following observations and recommendations: 

1. Cinergy should consider working toward obtaining The National Arbor Day Foundation’s 

(NADF) Tree Line USA32 designation, and becoming a member of the EPA’s Pesticide 

Environmental Stewardship Program33 (PESP). In addition to helping the utility stay focused 

on important activities such as worker training, public education, and the use of proper tools 

and techniques, these programs act as a baseline measurement of overall program efficacy. 

In other words, we would expect that any utility company that wishes to have a “Best-inClass” UVM program, would naturally have first obtained the Tree Line USA designation and 

be an active participant in the PESP program. In our opinion, they are both basic measures 

of general UVM competence and we encourage all utilities to become involved with these 

programs. 

 

32 http://www.arborday.org/programs/treelineusa.html 33 http://www.epa.gov/oppbppd1/PESP/about.htm
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2. We found no evidence that Cinergy is fully utilizing appropriate methods for tracking and 

managing overall UVM operations. We believe that more emphasis should be placed on the 

ability to predict, monitor, and adjust, as necessary, to changing conditions. For example, 

Cinergy apparently does not track the total number of trees pruned or removed on an annual 

basis. We would suggest that this type of information is critical for various reasons ranging 

from the development of unit price contracts, to tracking improvements in productivity. We 

would suggest that Cinergy review their current measurement systems to ensure they are 

accurately capturing the right information to track and monitor their program efficacy. 

3. We recommend that Cinergy review current tree-related outage reporting criteria and 

procedures. The fact that Cinergy could not provide outage data that differentiated between 

“avoidable” and “unavoidable” causes us to believe there may be a problem here (in addition 

to the more general issues discussed elsewhere regarding the use of these terms). As 

should be obvious, the key indicator of UVM program efficacy at any utility company is found 

in the company’s ability to prevent or reduce outages. Without accurate, consistent, and 

meaningful data, it is hard to evaluate which direction your UVM efforts are taking you. 

4. Finally, we recommend that Cinergy consider adopting all of the general recommendations 

referenced in this document. Cinergy should work toward incorporating all Best 

Management Practices into their program, and work with appropriate parties to remove 

obstacles to completing required work. 
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DETAILED UVM RESPONSES34

# Review Questions FE Cinergy AEP 

3.1 Total Customers 2,124,915 1,519,701 N/a 4.1 Transmission Circuit Miles 69kV – 2,277 

138kV – 3,724 345kV – 1,197 

69kV and above 7,198 

69kV – 3,233 

138kV – 2,170 

230kV – 888 

345kV – 2,049 

69kV and above 8,340 

23kV – 112 

34.5kV – 366 

40kV – 59 

69kV – 2,625 

138kV – 3,284 345kV – 1,793 

765kV – 509 

69kV and above 8

4.5 Group that manages UVM 

Distribution and Transmission 

Regional Forestry 

Operations – Both T&D 

Shared responsibility 

When T&D facilities are on 

the same pole trimming is 

performed to the T spec 

AEP Forestry 

Both T&D 

5.1 Governing Agencies PUC of Ohio 

Penn. PUC 

FERC 

PUC of Ohio 

Indiana URC 

PSC of Kentucky 

FERC 

PUC of Ohio 

FERC 

5.2 Other Agencies National Parks 

Metro Parks 

ODOT 

USFS 

Ohio DNR 

DOT 

City & County Parks 

USFS 

US Army Corp of E

Ohio Div of Wildli

Metro Parks 

6.1 Budget – Excluding 

overheads (REDACTED) 

2000 – 2001 – 2002 – 2003 – 

1998 – 1999 – 2000 – 2001 – 2002 – 2003 – 

1998 – 1999 – 2000 – 2001 – 2002 – 2003 – 

 Actual 

(REDACTED) 

2000 – 2001 – 2002 – 35

2003 – 

1998 – 1999 – 2000 – 2001 – 2002 – 

1998 – 1999 – 2000 – 2001 – 2002 – 2003 – 

34 Responses reflect Ohio operations only, unless otherwise noted. 35 Average cost per mile can vary based on a number of variables such tree density, urban and rural mix, and accessibility. 
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# Review Questions FE Cinergy AEP 

6.2 Budget – Overhead costs 

(REDACTED) 

N/a 1998 – 

1999 – 2000 – 2001 – 2002 – 2003 – 

1998 – 1999 – 2000 – 2001 – 2002 – 2003 – 

 Actual 

(REDACTED) 

N/a N/a 1998 – 

1999 – 2000 – 2001 – 2002 – 2003 – 

7.1 Program Structure De-centralized Centralized Centralized 7.2 System Forester Yes Yes Yes 7.3 Full-time staff In-house – 25 

Contracted - 6 

In-house - 15 In-house – 4 

7.4 Part-time staff In-house – 1 

Contracted – 1 

0 In-house – 2 

9.1 # of Transmission Crews 39 Ohio/Kentucky – 18 

Indiana - 21 

43 

9.2 Crews Dedicated to 

Transmission 

20 – T only 

19 – T&D 

Ohio/Kentucky – Yes 

Indiana – No 

Yes 

9.2 In-house vs. Contracted 100% Contracted 100% Contracted 100% Contracte10.1 Trees Managed Trans. 283,445 

Dist. 2,749,427 

Do not track Trans. 437,400 

10.2 Transmission acres 56,405 91,000 103,812 10.3 Inventory Yes – system wide36 Yes – Indiana only37 Yes – system wid

36 Based on completed work only 37 Based on brush reports or completed work only 38 Based on completed work only 
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10.6 Trees per circuit mile 40 Unknown 50 10.14 Primary Inventory use Work planning Work direction Work planning & 

direction 

11.1.1 Units used to track cost Trees pruned and 

removed 

Acres of brush cut 

Acres of brush cut 

Line mile 

Acres of brush sprayed 

Trees pruned & 

removed 

Acres of brush cu

Line mile 

Circuit 

Herbicide 

Mowing 

11.1.2 Cost per tree 

(REDACTED) 

2000 – 39

2001 – 2002 – 40

Not tracked 2001 69kV – 138kV – 345kV – 2002 Same 

2000 – 2000 – 2001 – 2001 – 2002 – 2002 – 

11.2 Transmission trees pruned 2000 – 19,266 

2001 – 20,092 2002 – 19,254 2003 – 17,748 proj. 

Not tracked 1999 – 14,014 

2000 – 15,759 2001 – 9,348 2002 – 10,723 2003 – 15,000 proj. 

11.3 Transmission trees 

removed 

2000 – 32,364 2001 – 36,075 2002 – 36,64141

2003 – 25,736 proj. 

Not tracked 1999 – 53,611 

2000 – 42,250 2001 – 30,205 2002 – 21,591 2003 – 23,000 proj. 

11.4 Separate hazard tree 

program 

No No No 

39 Pruned & removed 40 FE note: Cost per tree affected increased due to more emphasis on removals (see footnote below) 41 No significant increase in removals noted from 2001 to 2002 
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11.6 Acres or miles mowed 2000 – 108.08 acres 

2001 – 564.82 acres 2002 – 846.9 acres 2003 – 274.57 proj. 

1998 – 50 acres42

1999 – 220 acres 2000 – 180 acres 2001 – 340 acres 2002 – 179 acres 2002 – 100 proj. 

1999 – 576.5 acres 2000 – 882.94 acre2001 – 821.73 acre2002 – 722.59 acre2003 – 1,000 proj. 

11.7 Acres or miles treated with 

herbicides 

2000 – 2,376 acres 2001 – 2,492 acres 2002 – 2,097 acres 2003 – 2,098 proj. 

1998 – 90 acres43

1999 – 100 acres 2000 – 120 acres 2001 – 232 acres 2002 – 356 acres 2003 – 520 proj. 

1999 – 2,478.86 ac2000 – 2,962.86 ac2001 – 3,097.72 ac2002 – 4,335.67 ac2003 – 4,450 proj. 

12.1 On cycle? Yes Generally cyclic Yes 12.1.1 Does cycle vary based on 

location 

No, all T lines are on a 5 

year cycle, although our 

practice recognizes that 

for some locations, more 

frequent spot control is 

required, such as urban 

areas or where conditions 

limit tree to conductor 

clearances (i.e., through 

easement restrictions). 

Yes Yes 

12.1.2 If yes, provide cycle 5 years Urban/Sub – As needed 

Rural – As needed 

Side trim – 4-5 years 

Mowing – As needed 

Herbicide – 4-5 years 

Urban/Sub – 2-4 y

Rural – 6-8 yrs 

12.5 Work schedule is based on Cycle based 

By circuit 

Condition based 

Work is prioritized based 

on line inspection, past 

work history and current 

observations of the circuits 

Cycle based 

By circuit 

Reliability based 

42 Ohio and Kentucky only 43 Ohio and Kentucky only 
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12.7 Tree definition A woody plant six inches 

(6”) in diameter at four 

and one-half feet (4.5’) 

above the ground (dbh) 

will be considered for 

purposes of recording a 

tree. All growths less 

than this measurement 

will be considered brush. 

Woody vegetation greater 

than 4 inches DBH 

Greater than 4 inch

DBH 

12.8 Brush definition A woody plant less than 

six inches (6”) in 

diameter at four and onehalf feet (4.5’) above the 

ground (dbh) 

Woody vegetation less 

than or equal to 4 inches 

DBH 

Less than 4 inche

DBH 

12.9 Pruning methods Shigo 

A-300 Standard 

ISA Pruning Standard 

Directional Pruning 

Shigo 

A-300 Standard 

Directional Pruning 

Local Ordinances 

Shigo 

A-300 Standard 

ISA Pruning Stand

Directional Prunin

12.11 Documented removal 

policy 

Yes No Yes 
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# Review Questions FE Cinergy AEP 

12.11.1 Removal criteria Dead or defective 

which constitute a hazard to the conductor. 

Trees that have fast 

growth rates or trees that cannot be pruned for effective conductor clearance. 

Immature trees, 

generally classified as brush. 

Trees that are 

overhanging the primary conductors and are unhealthy or structurally weak. 

All priority trees 

located adjacent to the sub-transmission and transmission clearing zone corridor that are leaning towards the conductors, are diseased, or are significantly encroaching the clearing zone corridor. 

All incompatible trees 

that are located within the clearing zone corridor. 

Specifications require that 

all trees and brush be 

removed from ROW when 

possible 

Page 11 of policie
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# Review Questions FE Cinergy AEP 

12.14 IVM managed 100% are IVM managed. 

All locations are 

evaluated for costeffective control, and 

cycle is a key driver for 

when an area is 

maintained. The 

FirstEnergy Vegetation 

Management 

specifications and cycle 

were developed with 

threshold controls, costeffectiveness, safety, 

environmental concerns, 

public relations, and 

reliability all taken into 

consideration. 

70% IVM 

30% no action needed 

100% 

12.18 Tree growth regulators 

used 

Yes Yes Yes, limited 

12.18.1 Why are they used When necessary due to 

easement restrictions 

Easement limitations 

Property owner request 

In situations where 

tree cannot be 

removed and is 

situated directly un

our facilities TGR 

used on faster grow

species. Primarily 

would be in an urba

street setting, and 

tree would be a “cy

buster” 

13.3 Initial clearing widths 69kV – 50’ 

138kV – 110’ 345kV – 170’ 

69kV – 50-100’ 

115kV – 100’ 230kV – 150’ 345kV – 150’ 

69kV – 70’ 

115kV – 100’ 345kV – 125’ 

500+kV – 175’ 

44 See Page 73 for discussion on Integrated Vegetation Management. 
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# Review Questions FE Cinergy AEP 

13.10 Documented rights on 

ROW 

Yes Yes, in most ROW 

documents. Some 

documents specify only 

maintenance rights 

Yes, easements 

13.12 Notification by Contract Inspector Contract Inspector 

Crew Foreman 

Contract Inspecto

13.15 Non-routing work (tag 

work) 

1-15% depending on 

region 

25% 3% 

13.23 Most difficult agency Local City or County Local City or County Local City or Coun13.27 Restrictions that hinder 

work 

Where there is a delay in 

issuing permits, the co’s 

VM work schedule is 

impacted 

No Yes, the propertie

should be manag

with IVM technique

all easements 

13.28 Examples of process 

delays that caused problems 

No formal documentation N/a Yes, Wayne Natio

Forest 

14.3 Work with engineering 

dept. 

Yes Yes Yes 

14.3.1 Explain interaction with 

engineering 

Company forestry 

personnel participate in 

regularly scheduled 

planning meetings with engineering personnel, 

attend joint field visits, 

and participate in routing 

decisions for 

transmission projects. 

Options are discussed if 

high volume tree impact is 

anticipated 

We communicate 

specs and input w

the ROW acquisit

group and the 

engineering desig

group 

15.1 Are UVM services 

contracted 

Yes Yes Yes 
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# Review Questions FE Cinergy AEP 

15.2 Functions contracted Pruning & removal 

ROW clearing 

TGR’s 

Herbicide application 

Inventory work 

R&D 

Clerical support 

Pole clearing 

Pruning & removal 

ROW clearing 

TGR’s 

Herbicide application 

Pruning & remov

ROW clearing 

TGR’s 

Herbicide applicat

Pre-inspection 

Clerical support 

15.4 Securing UVM services Typical bidding process 

Negotiated prices 

Typical bidding process 

Negotiated prices 

Typical bidding proc

15.6 Typical Contract term 1 year or multi-year 3 years with an option to 

extend 

5 years 

15.8 Contract structure 40% T&M 

50% Lump Sum 

10% Other – 

performance based 

25% T&M 

75% Unit Price 

99% T&M 

< 1% Unit Price 

< 1% Lump Sum 

15.14 Contractors 8 vendors perform UVM 

work 

5 vendors perform UVM 

work 

2 Line Clearance 

3 Work Planning 

16.1 Laws & regulations that 

apply 

N/a NESC Rule 218 

USFS other Fed. Req. 

Commission 

State Highway Req. 

Local Street Tree Ord. 

Other local Ord. 

NESC Rule 218 

State Highway Re

Local Street Tree O

Other local Ord

16.3 Must clearances be 

maintained 

N/a No No 

16.5 % in contact w/T now None, to the companies 

knowledge 

Not tracked but minimal < 2% 

16.6 % in contact w/T at pruning N/a Not tracked but minimal < 2% 16.9 Right-tree Right-place Yes Yes Yes 

45 Most often driven by the size of the program. 
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# Review Questions FE Cinergy AEP 

17.1 Program drivers N/a No formal ranking but 

safety and reliability are 

held in the highest regard 

1 – Service Reliab

2 – Prevent accide

3 – Prevent fires 

4 – Customer serv

5 – Comply with la

18.3 Avoidable vs. unavoidable N/a 

N/a 

2000 – 75% A, 25% U 2001 – 57% A, 43% U 2002 – 25% A, 75% U 

N/a 1998 – 25% A, 75% 

1999 – 25% A, 75%2000 – 25% A, 75%

2001 – 25% A, 75% 2002 – 25% A, 75% 

19.1 Fires in the last 5 years None Yes None 20.1 Drought and rainfall data 

used 

No No No 

21.1 Ratemaking procedure No rate case in Ohio No rate case in Ohio No rate case in O21.2 Requested 

Authorized Actual 

See 6.1 See 6.1 See 6.1 

21.4 Adequately Funded? Yes The program is adequate 

to maintain the primary 

objectives of safety and 

reliability 

Yes 

21.6 Expenditures tracked by 

voltage? 

No N/a See 6.1 & 6.2 
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VI. RECOMMENDATIONS 

GENERAL INDUSTRY RECOMMENDATIONS 

Reducing the likelihood of future tree and power line conflicts will require significant changes in 

industry practice, and may initially cost more money to accomplish. It may also require a great 

deal of political leadership. 

We are submitting the following general recommendations as initial steps that can be taken to 

mitigate and or prevent future problems related to tree and power line conflicts. This is followed 

by specific recommendations regarding oversight and enforcement of UVM activities by the 

appropriate entities. 

1. DEVELOP MEASURABLE AND ENFORCEABLE STANDARDS FOR UVM PROGRAMS

The current set of industry rules, guidelines, and/or laws are not explicit enough to ensure that 

utilities will strive toward the elimination of future similar occurrences (See discussion on Page 

68). The agencies responsible for utility oversight have not focused, to the extent necessary, 

their attention on this critical function. 

UVM requirements and standards must be better defined and enforced. Whether it occurs at a 

local, state/provincial or federal level, the agencies and organizations responsible for oversight 

of utility operations need to ensure development and enforcement of clear and consistent 

performance standards regarding the prevention of tree and power line conflicts. Further, 

regulators and/or oversight organizations should perform routine UVM reviews at the utility 

companies working under their aegis 

2. INSURE THAT THESE EFFORTS ARE ADEQUATELY FUNDED

 

UVM programs have always been prime targets for short-term budget reductions by utility 

companies. Unfortunately, the real cost of these reductions does not typically manifest itself for 

months or even years. We also know that the perceived short-term savings actually translate 

into exponentially higher costs in the future. Utility companies should have clear regulatory 

incentives for adequately funding (and disincentives for inadequately funding) this important 

function. 

Where applicable, the agencies and/or Commissions responsible for authorizing these 

expenses should adequately fund these programs to the extent necessary to meet reasonable 

requirements and objectives. 

3. PROVIDE THE RIGHT TO PERFORM THE WORK

As it stands right now, utilities are placed in the untenable position of having the obligation to 

keep vegetation from conflicting with power lines, but not always the explicit right to do it (See 

Appendix ‘E’ for an example of restrictive rights). We should either find effective ways to provide 

the right to perform this work to the utility (in both emergency and routine situations), or accept 

that they cannot do all the work required to prevent future outages or fires. 

It is interesting to note that the government of New Zealand has, within the last few months, 

taken a very bold step forward in addressing the dilemma of utilities not having the explicit right 
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to perform the work on other people’s trees. New Zealand now requires that the cost and 

obligation of maintaining the trees away from electric lines be borne by the person who actually 

planted or owns the vegetation. While extremely controversial, this provides an “out-of-the box” 

resolution to many of the problems we currently face in North America. 

4. ELIMINATE UNNECESSARY OBSTACLES

Local, state/provincial, and federal governments should review existing requirements that serve 

to unnecessarily stop or hinder the timely completion of required UVM work. Where possible, 

acceptable standards and requirements should be developed that can be uniformly applied to 

UVM operations (permitting requirements, work standards, removal criteria, etc.). 

5. REQUIRE PROPER PLANTING OF VEGETATION NEAR POWER LINES

The simple act of choosing the appropriate species of vegetation to plant near overhead lines 

would save hundreds of millions of dollars annually for electric ratepayers in North America. It 

would also result in a dramatic reduction in the likelihood of future outages and fires, and a 

conversely dramatic improvement in the health of our urban and rural forests. Additional 

ancillary benefits include a tangible reduction in herbicide and chemical usage, and an equal 

reduction of needless biomass waste being produced and disposed of as a result of the 

unnecessary pruning and/or removal of trees and vegetation. 

RECOMMENDATIONS FOR OVERSIGHT AND ENFORCEMENT OF UVM ACTIVITIES 

Current oversight of UVM activities by appropriate agencies or organizations is overwhelmingly 

inadequate. While there is no shortage of concern regarding preventing tree and power line 

conflicts, we believe that there needs to be a more focused and educated approach to 

overseeing the efforts of utility companies in this critical activity. Equally important, these entities 

need to develop and enforce specific and measurable objectives for the utility companies 

working under their aegis. While utility companies have the expertise to improve UVM activities 

in North America, we do not believe we will see a dramatic improvement without rigorous 

oversight by the appropriate authorities. 

The following are recommendations regarding how to improve current oversight and 

enforcement of UVM activities: 

1. OVERSIGHT AGENCIES AND ORGANIZATIONS NEED TO LEARN MORE ABOUT UVM 

ACTIVITIES

While trees may be the single largest cause of electrical outages, few oversight agencies or 

organizations can claim they have the internal expertise to address and correct UVM issues and 

problems. This expertise is fundamentally important in that any new requirements or 

expectations placed on utilities can have a dramatic effect on energy costs, public safety, 

customer satisfaction, and the environment. We recommend that internal staff at these 

organizations receive, at minimum, rudimentary training on all aspects of UVM. 

2. DEVELOP CLEAR UVM PROGRAM EXPECTATIONS FOR UTILITY COMPANIES 

Oversight organizations should work with the utility companies, the UVM industry, and other 

stakeholders to develop measurable and achievable program objectives. The development of 

these expectations will require a joint effort to identify what specifically can be done to ensure 
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the reduced likelihood of future tree and power line conflicts. Given the myriad of site-specific 

UVM related variables throughout North America, we would expect that these expectations may 

differ based on local environmental conditions and other factors. With that caveat, we offer the 

following three examples of items that could be included as part of these expectations: 

• Adoption of specific UVM Best Practices 

• Development of, and adherence to, comprehensive UVM schedules 

• Achieving specific reductions in tree-related outages 

3. DEVELOP INCENTIVES/PENALTIES FOR COMPLIANCE

Oversight organizations should develop, communicate, and enforce clear incentives and/or 

penalties related to utility-specific performance. 

4. ENFORCEMENT AND OVERSIGHT SHOULD BE ROUTINE

Oversight organizations should continually monitor utility-specific UVM program activities and 

progress. This could be accomplished through standard utility reporting requirements, regular 

meetings between staff and the utility, and verification of progress through routine field audits. 

Specific attention should be paid to the issue of adequate inspections and scheduling of work. 

As we have stated in various sections of this report, the objective of UVM should be to identify 

and correct tree and power line conflicts “prior” to them creating problems. 

5. OVERSIGHT ORGANIZATIONS NEED TO BECOME DIRECTLY INVOLVED IN UVM 

ACTIVITIES WHERE APPROPRIATE

There are numerous situations where responsible agencies and organizations can actually 

assist in reducing the likelihood of tree and power line conflicts. For example, fire officials in the 

west routinely assist utility companies when they encounter refusals46. Similar effective 

intervention could be provided by oversight organizations or agencies. Another common 

problem occurs when local governments erroneously restrict or prevent the timely completion of 

required UVM work47. We believe that in situations where the legal authority for developing and 

enforcing UVM requirements is held by a specific state or federal oversight organization, that 

authority should not be superceded by possibly competing local interests. At a minimum, utility 

regulators should become involved in representing the public interest in avoiding tree-related 

outages. 

We believe that the preceding recommendations (if adopted by oversight organizations) will 

result in a dramatic reduction in the future likelihood of tree and power line conflicts. While the 

majority of these organizations are not currently involved with UVM activities to the degree 

proposed here, it does appear that a few States’ have begun to take important steps in this 

direction. Several State requirements are described in Appendix ‘H’ and vary from Commission 

to Commission. Some provide fairly detailed guidelines while others have minimum 

requirements for UVM maintenance and activities. 

 

46 See Page 18, Influence of Property Owners. 47 See Page 15, Competing Interests. 
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VII. BEST MANAGEMENT PRACTICES 

BACKGROUND 

One of our initial tasks was to develop a list of Best Management Practices (BMP) that could be 

applied to all transmission UVM programs. In order to accomplish this, we felt it was appropriate 

to seek input from a wide audience of experts in the UVM field, in addition to drawing from our 

own experience and the available data. 

The following section was developed with the active participation of UVM experts in the US and 

Canada. These individuals were asked to contribute based on their reputations, knowledge of, 

and active participation in our industry. 

In addition to the development of the BMPs, we asked each of our experts to provide a written 

response to the following question: 

“As an industry expert, what would you recommend needs to be changed, improved, or 

fixed in order to reduce or prevent the likelihood of future tree and transmission line 

conflicts?” 

These insightful and candid commentaries are included in Appendix ‘J’. 

It should be noted that their contribution and involvement in the development of the Best 

Practices, and/or their commentaries in Appendix ‘J’, were on an individual basis, and the 

opinions and recommendations of each participant does not necessarily reflect the endorsement 

of their respective companies or organizations. Additionally, these experts were not involved 

with the development of this report, and did not have access to any data or information related 

to this investigation, other than what was available to the general public. 

BEST MANAGEMENT PRACTICES IN THE TRANSMISSION UVM INDUSTRY 

In the following section, we have identified specific “Industry Best Management Practices” for 

managing vegetation adjacent to electric transmission facilities. This list was developed by 

Stephen Cieslewicz and Robert Novembri of CN Utility Consulting, with the active support, 

input, and approval of the following industry leaders and experts: 

 Robert Bell, Pacific Gas & Electric Co., President of the Utility Arborist Association 

(California) 

 Scott Deevers, Business Manager, The Davey Tree Expert Company (Ohio) 

 Kevin Eckert, President and Managing Director, Arbor Global (Hawaii) 

 John Goodfellow (Redmond, Washington) 

 Siegfried Guggenmoos, President, Ecological Solutions (Alberta, Canada) 

 Richard Johnstone, System Forester, Conectiv/IVM Industry Consultant (Delaware) 

 Randall H. Miller, System Forester, PacifiCorp (Utah) 

 Mike Neal, Arizona Public Service, President of the International Society of Arboriculture 

(Arizona) 

 Jim Orr, Asplundh Tree Expert Company (Pennsylvania) 

 Derek Vannice, Executive Director of the Utility Arborist Association (Illinois) 

In general, BMPs are documented strategies and tactics accepted by leading industry 

organizations and employed by progressive companies to achieve specific objectives. For 

example, the acknowledged BMPs for pruning have been developed by a broad spectrum of 
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industry experts and are outlined in the American National Standard for Tree Care Operations 

A300 (Part 1)-2001, Pruning (See Appendix ‘K’). The methods defined in this document are 

currently the most effective way to protect the health of trees during line clearance pruning. 

“Best management practices” do not remain static over time. New laws, technology, products, 

tools, program objectives, research, and even public sentiment can influence and change what 

we presently understand about best practices. As such, we recommend periodic review of any 

set of best practices. 

The best practices presented below were developed with the specific intent of describing the 

safest, most environmentally sound and cost-effective methods and tools to “enhance system 

performance and transmission reliability.” This list represents “general” requirements for bestin-class UVM programs. The actual day-to-day operations and practices related to transmission 

UVM should be tailored to site-specific requirements and are much more detailed and technical 

in nature than could be described in this document. These technical best practices for UVM are 

typically referred to as Integrated Vegetation Management (IVM) techniques. For more 

technical details of what are considered best-in-class IVM practices, please consult the 

recommended readings listed in at the end of this section. 

BEST PRACTICES FOR NEW TRANSMISSION FACILITIES 

Designing New Line Routes 

New transmission lines should be routed with consideration of future reliability needs and 

maintenance. This should include an appropriate assessment and consideration of current and 

expected vegetation growth and encroachment. Considerations such as defining the appropriate 

ROW width, and the development of long-term UVM maintenance plans, should be addressed 

during the design stage and include the participation of the utility’s UVM experts. 

Discussion: The ideal transmission line route would be one where vegetation would not 

grow or fall into the facilities, given reasonable and ongoing maintenance. While this 

may not be realistic with many lines, it can and should be an objective for the siting of 

future lines. In order to meet this objective with future lines, a utility arborist should be 

involved to help support decisions on route selection and to develop the site-specific 

prescription to establish an appropriate ROW and maintain the line in the future. To be 

most effective, a vegetation management specialist should be included throughout the 

process from design through construction. This consultation can minimize environmental 

impacts, permitting requirements, future tree-related reliability threats and access 

problems, and can lower long-term financial and environmental costs. 

ROW and Easement Documents 

Easement documents should clearly provide the utility with rights to establish and maintain 

appropriate clearances under and adjacent to the proposed lines while utilizing all appropriate 

IVM practices. The ROW width should be determined based on the following objective: “No 

vegetation, or parts of vegetation, shall be allowed to grow or fall into the transmission facilities.” 

For example, if native trees have a mature height of 100 feet, the “ideal” initial easement should 

be wide enough to ensure that existing and future trees (along the side of the ROW) will not, by 

accident or design, fall into the facilities. 

The documents shall also clearly reference typical vegetation management work that can be 

expected in the future. For example, it should clearly permit the removal and/or pruning of any 

off-easement trees that are deemed by the utility to be a threat to the safe and reliable 

operations of the line. It should also specify the use of EPA-approved herbicides and growth 
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regulators as necessary to manage the vegetation in a cost-effective manner. Easement 

contracts should also state that the primary purpose of the ROW is safe and reliable delivery of 

energy services. 

Discussion: It appears that many utility companies rely on standard easement widths 

that are based on voltage, rather than the site-specific conditions. For example, many 

right-of-way documents state, “the utility shall have the right to adequately maintain the 

line.” We think such language is inadequate to avoid misunderstandings over the scope 

of work. Rather, ROW widths should take into consideration specific factors such as 

conductor sag and sway, topography and the mature height of local vegetation, among 

others. Finally, easement contract wording should be explicit about the nature of the 

vegetation work required along the corridor. This would include specific references to 

the use of all potential IVM techniques, including herbicides. 

Initial ROW Establishment 

Initial clearing and ROW establishment should be extensive enough to provide safe and reliable 

energy services with allowance for future growth of desirable vegetation to its intended mature 

height. The ROW should be cleared in a manner consistent with a long-range vegetation 

management plan, and with the achievement of “Wire Zone, Border Zone” objectives. This 

involves shifting plant communities found on the current ROW away from predominately tallgrowing plant species in favor of naturally low-growing plant species. These plant communities 

of low-growing vegetation provide a biological control of undesirable plants by inhibiting their 

establishment, resulting in a more environmentally and aesthetically stable ROW environment. 

This conversion is accomplished by selectively controlling tall-growing plant species while 

preserving and encouraging low-growing trees, woody shrubs, grasses, herbs, and forbs. The 

establishment of this new environment typically requires successive cycles of work and the 

selective and judicious use of herbicides to fully control the entire undesirable target plant. 

Discussion: Studies have demonstrated that this practice, involving maintaining ROW 

corridors as distinct ecosystem zones, is cost effective, provides significant 

environmental and societal benefits, and will improve electric service reliability. Properly 

managed, these linear corridors can become an asset for forest ecology and forest 

management. The benefits to wildlife associated with the “edge-effect” are well 

documented by the 50 years of research at the Bramble and Byrnes study areas. For 

example, rare and endangered plants frequently find a refuge on these well-managed, 

open corridors. In addition, significant increases of birds and other wildlife are well 

documented. Finally, and equally important, such corridors have the proven potential to 

serve as firebreaks and/or staging areas and access points to assist in wildland firefighting efforts. 

BEST PRACTICES FOR ONGOING TRANSMISSION UVM OPERATIONS 

Understanding the Workload 

Workload projections, planning, budgeting, and scheduling should be based on an accurate 

understanding of the existing and likely future vegetation under and adjacent to existing 

transmission lines. 

Discussion: While there are utility companies that have an actual inventory of 

vegetation, most do not have a complete picture of the workload on their transmission 

system. We believe that in order to adequately manage a dynamic population of 

vegetation, the utility should have accurate baseline information that is adequate to plan 
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and perform effective UVM activities. This should also include estimates of future 

natural re-growth or planted vegetation that will likely be experienced. 

Funding 

Consistent funding should be based on a clear understanding of the required work, and not be 

solely based on historic budgets. Funding should be based on an accurate understanding of 

workload and local knowledge of the type, cost, and frequency of required work. This should 

also include the ability to increase or reduce expenses (in a timely manner) in response to 

unpredictable events. For example, this would include the ability to adjust funding based on the 

unexpected impacts of drought and above normal precipitation, or widespread outbreaks of tree 

pathogens or pests. 

Discussion: A common industry complaint is that UVM budgets are somewhat unstable. 

This includes annual unpredicted budget spikes (up and down) for reasons not related to 

actual workload. Additionally, there does not seem to be adequate funding mechanisms 

to address uncontrollable outbreaks of vegetation-related problems. It is critical to 

understand that trees and vegetation grow based on natural moisture and other climatic 

factors with no recognition of financial conditions. 

Scheduling UVM Work 

Scheduling should be based on an updated and ongoing analysis of the workload and current 

conditions. For example, both excessive precipitation and drought can significantly influence 

vegetative growth and resulting workloads. Schedules should be flexible enough to address 

these and other variables such as customer- and line-patrol-initiated work. The intent of 

scheduling is to manage the vegetation prior to it becoming a threat to service reliability. 

Discussion: The key to a successful transmission UVM program is found in its ability to 

predict and mitigate problems. This involves the development and continuous updating 

of, and adherence to a long-term schedule. Vegetative growth and plant succession are 

dynamic processes that require prescriptive and proactive management. One cannot 

manage what is not known, thus a successful program requires ongoing knowledge of 

the changing ecosystem and the efficacy of the management inputs. It also requires the 

monitoring and response to unanticipated work that can be generated through customer 

or agency notifications, or other utility patrols and requirements. UVM schedules are not 

static, but, like funding requirements, are based on naturally influenced growth 

conditions. 

Wire Zone – Border Zone Concepts and Integrated Vegetation Management (IVM) 

All transmission UVM work should be identified, scheduled, completed and maintained 

consistent with “Wire Zone – Border Zone” objectives and industry accepted protocols. 

Integrated Vegetation Management (IVM) is the most commonly referred to, and used, protocol 

for managing transmission rights-of-way. IVM is generally defined as the practice of promoting 

desirable, stable, low-growing plant communities that will resist invasion by tall growing tree 

species through the use of appropriate and environmentally sound control methods. These 

methods can include a combination of chemical, biological, cultural, and/or mechanical 

treatments. 
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Bramble and Byrnes Wire Zone – Border Zone 

(From Yahner, Bramble and Byrnes, 2000) 

Discussion: As previously mentioned, utilities should work toward the achievement of 

“Wire Zone – Border Zone” objectives on new and existing ROWs. This involves shifting 

plant communities found on the current ROW away from predominately tall-growing 

plant species in favor of plant communities dominated by naturally low-growth plant 

species. This shift is accomplished by selectively controlling tall-growing plant species, 

while preserving and encouraging low-growing trees, woody shrubs, grasses, herbs, and 

forbs. The establishment of this new cover type typically occurs after successive cycles 

of work and requires a long-term commitment from the utility. In determining the sitespecific requirements to achieve the Wire Zone, Border Zone ideal, a variety of 

vegetation management techniques is considered. These may include biological, 

chemical, cultural, manual, or mechanical techniques. The choice of the best 

technique(s) is based on effectiveness, environmental impact, site characteristics, 

worker and public health and safety concerns, and economics. 

Transmission Line Sag and Sway 

Conductor sag and sway must be considered whenever managing transmission ROWs. Utility 

and contract employees shall be familiar with how conductor sag and sway can influence 

clearances on specific ROWs under normal and short-term emergency load conditions. Such 

elements as training, work assignments, contract specifications, and UVM manuals should 

include instructions for determining potential sag and sway at specific locations. 

Discussion: When clearing or maintaining transmission ROWs, it is incumbent on 

employees to consider the potential sag and sway of conductors as it will influence 

clearance between vegetation and the lines. Failure to recognize and consider the 

impacts can lead to unexpected or premature contact between vegetation and the 

conductors. 

Reclaiming ROWs 

Transmission UVM programs should identify all sections of line that are not currently managed 

to the full extent of easement rights, the Wire Zone – Border Zone method or with other 

compatible land use. A plan should be developed that methodically works toward the goal of 

putting all ROWs under this or other compatible method of routine management. 

Discussion: Many utility companies may have full documented rights to perform UVM 

work but, due to various reasons, have allowed the vegetation to become unmanaged. 

Each utility should assess the condition of all ROWs and work toward achieving 
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complete system management and fully adhering to documented easement rights. It 

should be noted that Wire Zone – Border Zone practices are not likely to be achieved in 

all locations. For example, where transmission lines are routed through heavily 

populated areas, such things as existing landscaping, property owner objections, a lack 

of documented easement rights, and other local restrictions will make it unlikely that 

these types of clearances can be achieved or maintained. Work should be prioritized 

based on the extent of potential interference, voltage of the system, and relative 

importance of the circuit as a radial feed versus one with built-in redundancies. 

Inspections of Vegetation Conditions 

Field inspections of vegetation conditions should occur on a frequent basis, and the schedule 

should be based on anticipated growth. Aerial patrols should be complemented and calibrated 

by routinely scheduled ground patrols. 

Discussion: It is important to perform routine inspections of all transmission facilities for 

potential conflicts involving vegetation. These inspections should be performed by 

qualified individuals and be scheduled to ensure that all transmission lines are 

systematically reviewed before conflicts occur. All inspections should be adequately 

documented and followed up on to ensure timely completion of the identified work 

requiring attention. The inspection cycle and schedule should be based on the predicted 

growth of existing vegetation. It should supplement, not replace, other utility line 

inspections. While helicopter patrols are adequate for many locations, ground patrols 

should be utilized whenever there is the possibility of not being able to accurately identify 

clearances between lines and vegetation. 

Organizational Structure 

Transmission UVM programs should be centralized within the utility and under the authority of a 

qualified, experienced and knowledgeable vegetation manager. 

Discussion: We recommend that management authority and control of transmission 

UVM programs be centralized within the utility company in order to ensure consistency 

in practices and the appropriate utilization of available resources. We do not believe 

that the integrity of the entire system can be effectively maintained if the management 

is de-centralized. Transmission and distribution UVM activities can, however, be 

combined or separated as stand-alone programs based on the workload and desires 

of the utility. We also recommend that the program(s) have oversight from a qualified 

Utility Arborist. 

Management Support 

Utility management throughout the organization should support and be familiar with the 

necessity of and practices involved with UVM activities. 

Discussion: Management from the CEO down needs to understand and support the 

UVM program and efforts. This support should be evidenced by reasonable and 

consistent funding, and demonstrated support for the use of applicable UVM techniques. 

Another important example would be the active and timely management support in 

resolving individual or agency refusals. (Refusals occur when an individual or entity 

stops or restricts the ability to perform required UVM work.) 

Note: Many of the difficult political and financial problems related to vegetation 

management activities result from a lack of understanding by those in a position of 

power at the utility company. Communication skills are necessary for Utility Arborists to 
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educate and inform, not only those directly related to the vegetation management 

program, but also to those in a position where funding and support are crucial to the 

program’s success. 

Qualifications 

Utility and contract employees at all levels in a UVM program should have appropriate 

qualifications, ongoing training, and applicable certifications to perform the required work. 

Discussion: In addition to applicable pesticide training and certifications, employees 

can utilize the existing industry credentials of the International Society of Arboriculture, 

including ISA Certified Tree worker, ISA Certified Arborist and ISA Certified Arborist 

/Utility Specialist. An ongoing training program is needed to maintain the credentials and 

provide a well-trained, motivated work force. 

Research and Development 

Utilities should have ongoing R&D efforts to evaluate current and potential tools and practices 

related to UVM work. The company should continuously evaluate new technology, products 

and work methods that are aimed at program improvement. 

Discussion: While a full blown R&D program may not be practical at many utility 

companies (due to size, etc.) efforts should be undertaken by all utilities to support, 

monitor, and/or perform UVM-related research and development. 

Clearly Defined, Communicated and Measured Objectives and Milestones 

Utilities should have a formal management plan outlining UVM practices, objectives, and 

approved procedures. The plan should also include workload-related references and 

projections. The utility shall have a documented schedule and appropriate measures to ensure 

completion of required work. The management plan will require periodic revisions 

Discussion: In order to ensure UVM efficacy, it is important to document, review, and 

ensure completion of appropriate plans and objectives. They need to continuously 

monitor performance and obtain compliance with reasonable goals and objectives. 

Quality Assurance Procedures 

Utilities should have a quality assurance program, and a documented procedure for ensuring 

that work is completed per specifications and industry standards. In addition, there should be 

ongoing efforts and protocols to identify and correct quality problems and issues. 

Discussion: Utilities should incorporate fundamental “Quality” concepts into UVM 

programs. At many utility companies, QA procedures are limited to the post-auditing of 

completed work. We suggest more effort should be focused on building comprehensive 

Quality processes into UVM programs. Quality Control procedures need to be 

incorporated into work practices in the field. Quality Assurance oversight needs to be in 

place to confirm that work performed conforms to appropriate quality-driven work 

practices. A culture of quality needs to be inculcated throughout the vegetation 

management organization. 

External Education 

Utilities should have a comprehensive public education program that provides the public, 

individual landowners, and other agencies and groups with accurate information regarding 

Transmission UVM activities and practices. 
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Discussion: The majority of Utility Arborists recognize that there is a substantial 

disconnect between the public’s understanding of proper UVM techniques, and what is 

actually scientifically correct and necessary. This issue is particularly true when it comes 

to subjects such as proper pruning, how tree-related outages occur, and the safe and 

effective use of herbicides. We believe that one of the best ways to address these 

misunderstandings is through public and agency education programs. 

Internal Education 

Utilities and contractors should have internal training programs that provide ongoing training to 

UVM employees. Utilities should also provide training to other utility departments regarding 

UVM activities and objectives. 

Discussion: Given the scope of required knowledge relating to UVM activities, it is 

essential that ongoing education is available to both utility and contract employees who 

work in UVM programs. In addition, the work of UVM is influenced by, or does influence, 

a myriad of utility company activities. Examples include customer service, design 

engineering, construction, purchasing, and the legal, public relations and regulatory 

departments. We believe that each of these groups should have a solid understanding 

of utility company UVM activities. 

Work Management Measurement 

Utilities should have a system(s) and procedures capable of managing work identification, 

assignments, and the job status for required UVM work. This should include the ability to 

document and track historic work at any given location. 

Discussion: The utility should be able to monitor and document all UVM-related 

activities. 

Pruning and Clearances 

Pruning shall be done in accordance with ANSI A300 guidelines. Clearances, obtained at time 

of pruning, shall be achieved with specific consideration given to line sag and sway, expected 

weather conditions, and the anticipated pruning response of the specific tree. 

Discussion: A300 pruning guidelines should be followed, and the clearance should be 

based on the tree and utility-specific circumstances. Pruning can be complemented by 

the use of tree growth regulators. These chemicals can reduce shoot growth and 

corresponding line interference. Application of bud-inhibiting chemicals to interfering 

branches on trees adjacent to ROW can prevent further growth and encroachment into 

the ROW. 

RECOMMENDED READING FOR BEST-IN-CLASS IVM PRACTICES AND OTHER 

REFERENCE MATERIAL 

1. Transmission System Vegetation Management Program, Environmental Impact 

Statement (DOE/EIS-0285) Prepared by the Bonneville Power Administration

Description: This Environmental Impact Statement (EIS) was prepared by the Bonneville 

Power Administration (BPA) in 2000, and was subsequently adopted and approved by the 

US Forest Service and the US Bureau of Land Management. This comprehensive document 

describes how BPA will manage its vegetation adjacent to transmission lines and corridors 

so as to ensure its intended operation. It contains valuable information on subjects ranging 

from Integrated Vegetation Management (IVM) techniques and tools, to detailed discussions 
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on the environmental impacts of transmission UVM work. While prepared specifically for 

BPA, the content is applicable to most UVM transmission programs in the US and Canada. 

2. The Edison Electric Institute’s “Draft” Memorandum of Understanding (MOU) 

Description: This “draft” MOU was developed by the Edison Electric Institute (EEI) 

Vegetation Management Task Force and has been presented to various US agencies. The 

intent of this document is to establish a framework for early cooperation and participation 

among the signatories that will enhance coordination of the processes under the National 

Environmental Policy Act of 1969, as amended, (NEPA) and other related statutes in 

connection with the authorizations that are required to maintain vegetation on the rights-ofway of electric utilities. Specifically, the intent of this MOU is to establish a process to ensure 

safe and reliable utility services while protecting and/or enhancing wildlife habitat on and 

adjacent to ROWs. It requires a focus on environmental stewardship while ensuring the 

timely development and completion of needed utility vegetation management projects. The 

MOU will also set a framework for EEI-member utilities to establish processes for the 

preparation of site specific vegetation management plans for agency consideration. 

3. Research of Drs. Bramble and Byrnes on the Pennsylvania Game Lands 33 Research 

Sites 

Description: The research work of Dr. William Bramble and Dr. W. Richard Byrnes (Purdue 

University) established the foundation for proper UVM activities along transmission ROWs. 

Their research, which has spanned the past 50 years, has resulted in a solid understanding 

of the appropriate techniques and environmental benefits associated with modern UVM best 

practice techniques. They have produced a tome of scientifically peer-reviewed data that is 

useful to all Utility Arborists, for example: Bramble, W.C., W.R. Byrnes, R.J. Hutnick and 

S.A. Liscinsky. 1991. Prediction of cover type of rights-of-way after maintenance 

treatments. Journal of Arboriculture. 17:38-43.

4. The ANSI A300 Standard and the “DRAFT” ANSI Standard for Integrated Vegetation 

Management (IVM) 

Description: Currently, proper pruning standards for UVM can be found in the American 

National Standard for Tree Care Operations A300 (Part 1)-2001 Pruning. Recently, an ANSI 

subcommittee has been formed to develop a draft of an additional ANSI standard that will 

cover IVM Practices. The International Society of Arboriculture (ISA), in collaboration with 

the Utility Arborist Association (UAA), will be developing a “Best Management Practice” 

document that will cover A300 pruning, and ultimately the standard on IVM. 

WEB SITE RESOURCES 

International Society of Arboriculture: Resources for the green industry at large. 

http://www.isa-arbor.com/

Utility Arborist Association: Resources for utility arborists. http://www.utilityarborist.org/

Tree Care Industry Association: Tree care standards and resources for tree care companies, 

educational and safety programs. http://www.treecareindustry.org/

The National Arbor Day Foundation: Tree Line USA, Tree City USA, educational information on 

right tree, right place concepts. http://www.arborday.org/index.html
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Tree Line Connection: Resources for utility arborists, links to utilities and state commissions. 

http://www.utilityarborist.com/

Pesticide Environmental Stewardship Program: EPA site for Integrated Pest Management. 

http://www.epa.gov/oppbppd1/PESP/about.htm

Project Habitat: BASF site for ROW management. 

http://www.vmanswers.com/default.asp?page=vmg|products|projectHabitat

Safe Tree: Public education about trees and power lines. http://www.safetree.net/

Safe Tree Kids: Educational tools for teachers and parents. http://www.safetreekids.net/
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VIII. LIST OF APPENDICES 

Appendix A: California Public Utilities Commission General Order 95, Rule 35 

Appendix B: Electrical Protection Act Alberta Electrical & Communication Utility Code 

Appendix C: Urban Wildland Interface Code 

Appendix D: Cinergy Tree Related Outage 

Appendix E: Examples of Absolute and Restrictive Easement Rights 

Appendix F: Ohio Rainfall Data 

Appendix G: Report by Dr. David Wood, Professor Emeritus, UC Berkeley 

Appendix H: Sample State UVM Standards and Requirements (Submitted October 2003) 

Appendix I: Engineering Assumptions 

Appendix J: Industry Recommendations 

Appendix K: ANSI A300, Section 5.9 – Utility Pruning 
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Appendix A: California Public Utilities Commission General Order 95, Rule 35 

Where overhead wires pass through trees, safety and reliability of service demand that tree 

trimming be done in order that the wires may clear branches and foliage by a reasonable 

distance. The minimum clearances established in Table 1, Case 13, measured between line 

conductors and vegetation under normal conditions, shall be maintained. (Also see Appendix E 

for tree trimming guidelines.) 

When a utility has actual knowledge, obtained either through normal operating practices or 

notification to the utility, dead, rotten and diseased trees or portions thereof, that overhang or 

lean toward, and may fall into a span, should be removed. 

Communication and electric supply circuits, energized at 750 volts or less, including their 

service drops, should be kept clear of limbs and foliage, in new construction and when circuits 

are reconstructed or repaired, whenever practicable. When a utility has actual knowledge, 

obtained either through normal operating practices or notification to the utility, that any circuit 

energized at 750 volts or less shows strain or evidences abrasion from tree contact, the 

condition shall be corrected by slacking or rearranging the line, trimming the tree or placing 

mechanical protection on the conductor(s). 

EXCEPTIONS: 

1. Rule 35 requirements do not apply to conductors, or aerial cables that comply with Rule 

57.4-C, energized at less than 60,000 volts, where trimming or removal is not practicable 

and the conductor is separated from the tree with suitable materials or devices to avoid 

conductor damage by abrasion and grounding of the circuit through the tree. 

2. Rule 35 requirements do not apply where the utility has made a "good faith" effort to obtain 

permission to trim or remove vegetation but permission was refused or unobtainable. A 

"good faith" effort shall consist of current documentation of a minimum of an attempted 

personal contact and a written communication, including documentation of mailing or 

delivery. However, this does not preclude other action or actions from demonstrating "good 

faith." If permission to trim or remove vegetation is unobtainable and requirements of 

exception 2 are met, the utility is not compelled to comply with the requirements of exception 

1. 

3. The Commission recognizes that unusual circumstances beyond the control of the utility 

may result in nonconformance with the rules. In such cases, the utility may be directed by 

the Commission to take prompt remedial action to come into conformance, whether or not 

the nonconformance gives rise to penalties or is alleged to fall within permitted exceptions or 

phase-in requirements. 

Mature trees whose trunks and major limbs are located more than six inches, but less than 18 

inches, from primary distribution conductors are exempt from the 18-inch minimum clearance 

requirement under this rule. The trunks and limbs to which this exemption applies shall only be 

those of sufficient strength and rigidity to prevent the trunk or limb from encroaching upon the 

six-inch minimum clearance under reasonably foreseeable local wind and weather conditions. 

The utility shall bear the risk of determining whether this exemption applies, and the 

Commission shall have final authority to determine whether the exemption applies in any 

specific instance, and to order that corrective action be taken in accordance with this rule, if it 

determines that the exemption does not apply. 
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Appendix B: Electrical Protection Act Alberta Electrical & Communication Utility 

Code 

SECTION 3.1.7 Tree Trimming 

(1) Subject to subsection (2), the operator of an electrical utility system shall ensure that trees 

near overhead power lines are trimmed so that the following clearances are maintained at 

all times, including the period of time between tree trims:

(a) a vertical clearance of 2.0 m plus the minimum distance to prevent flashover, from the 

conductors to any portion of a tree that will support a person; and 

(b) a vertical clearance of 600 mm plus the minimum distance to prevent flashover, from 

the conductors to any portion of a tree that will not support a person; and 

(c) a horizontal clearance of 1.0 m plus the minimum distance to prevent flashover, from 

the conductors to any portion of a tree that will support a person; and 

(d) a horizontal clearance of 300 mm plus the minimum distance to prevent flashover, 

from the conductors to any portion of a tree that will not support a person. 

(3) For overhead power or communication lines with metal sheathed, or polyethylene covered 

conductors, operated at voltages below 750 V between conductors, the minimum 

clearance between the conductors and trees shall be up to but not touching. 

(4) Where trimming is impracticable, the conductors shall be protected as necessary to 

prevent damage and electrical hazards. 
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Appendix C: Urban Wildland Interface Code 

2.3 Clearance of Brush and Vegetation Growth from Electrical Transmission and 

Distribution Lines. 

2.3.1 General. Clearance of brush and vegetative growth from electrical transmission and 

distribution lines shall be in accordance with Section 2.3. 

Exception: Section 2.3 does not authorize persons not having legal right of entry to enter on 

or damage the property of others without consent of the owner. 

2.3.2 Support clearance. Persons owning, controlling, operating or maintaining electrical 

transmission or distribution lines shall have an approved program in place that identifies poles 

or towers with equipment and hardware types that have a history of becoming an ignition 

source, and provides a combustible free space consisting of a clearing of no less than 10 feet 

(3048 mm) in each direction from the outer circumference of such pole or tower during such 

periods of time as designated by the code official. 

Exception: Lines used exclusively as telephone, telegraph, messenger call, alarm 

transmission or other lines classed as communication circuits by a public utility. 

2.3.3 Electrical distribution and transmission line clearances. 

2.3.3.1 General. Clearances between vegetation and electrical lines shall be in accordance with 

Section 2.3.3. 

2.3.3.2 Trimming clearance. At the time of trimming, clearances not less than those 

established by Table 2.3.3.2 should be provided. The radial clearances shown below are 

minimum clearances that should be established, at time of trimming, between the vegetation 

and the energized conductors and associated live parts. 

Exception: The code official is authorized to establish minimum clearances different than those 

specified by Table 2.3.3.3 when evidence substantiating such other clearances is submitted to 

and approved by the code official. 

2.3.3.4 Electrical power line emergencies. During emergencies, the utility shall perform the 

required work to the extent necessary to clear the hazard. An emergency can include situations 

such as trees falling into power lines, or trees in violation of Table 2.3.3.3. 

Table 2.3.3.2 – Minimum Clearances at time of trimming

Line Voltage Minimum Radial Clearance from Conductor (feet) 

2,400 – 72,000 4 

72,001 – 110,000 6 

110,001 – 300,000 10 

300,001 or more 15 

Table 2.3.3.3 – Minimum Clearances to be maintained

Line Voltage Minimum Radial Clearance from Conductor (inches) 

750 – 35,000 6 

35,001 – 60,000 12 

60,001 – 115,000 19 

115,001 – 230,000 30.5 

230,001 – 500,000 115 
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Appendix D: Cinergy Tree Related Outage 

The following report, provided by Cinergy, outlines the sequence of events leading up to the 

August 14th tree-related outage on the Bedford – Columbus 345kV Line. 

The August 14, 2003 tree related outage on the Cinergy transmission system was an atypical 

and isolated event that occurred on the Bedford – Columbus 34517 line. This event had no 

impact on, nor was it a contributing factor in the Northeast Blackout that occurred later in the 

day. The tree contacted the line on a property with a very dense growth of trees. A variety of 

issues had prevented the proper vegetation maintenance for safe and reliable operation of the 

line. 

In addition to the 34517 line, this location has two 230kv transmission lines (double circuited on 

one tower) that cross the property. The lines are positioned in a manner that the easements for 

345kv system and the 230kv system overlap. The property owner has frequently challenged 

Cinergy’s ability to conduct proper vegetation management arguing that the easements restrict 

the amount of trimming/clearing that Cinergy can do. Additionally, the property owner argued 

that the trimming/clearing damaged the lake on his property, negatively impacted his property 

value, created heath issues related to the use of chemicals, and increased security concerns 

from trespassers. Because of these various concerns, the property owner insisted that Cinergy 

schedule a time to perform any maintenance work at his convenience so that he could observe 

and protect his interest by limiting the amount of trimming that would be done. 

Various attempts had been made in past years, including in the spring of 2003, to negotiate a 

long-term settlement that was mutually acceptable to both parties, however the parties have 

been unable to reach agreement. 

On August 12, 2003, a routine aerial patrol identified the property as creating an imminent 

hazard. Based on this report, the property owner was contacted (as requested) to make 

arrangements for the crews to work. 

On August 14, 2003 at 0800hrs (EDT) crews arrived to perform the needed work. Several trees 

were trimmed, however, the property owner refused to allow the crew to complete the 

necessary trimming. By 1000hrs (EDT), the property owner had requested the crew leave the 

premises. 

At 1208hrs (EDT) the 34517 line locked out, and after investigation it was determined that the 

lockout was due to contact with a tree on this property. Tree crews were directed to the site to 

begin immediate corrective action. Work began to clear the wire zone at approximately 1530hrs 

(EDT), and the line was returned to service at approximately 1820hrs (EDT). Crews also 

returned on the following day to perform work in order to provide better clearance on the 230kv 

circuits. 

With the 8-14-03 event on the Cinergy system and the Northeast Blackout event, there was an 

even greater urgency to address fully the vegetation issues on this property. Additional 

discussions were held with the property owner, however, it became apparent that a mutually 

agreeable settlement could not be achieved within a reasonable timeframe. Mindful of the 

concern that another tree contact could happen, Cinergy developed an Action Plan to clear 

vegetation on the property to permit the safe and on-going reliable operation of the three 

circuits.
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The Action Plan was implemented on September 9, 2003, however, the property owner 

obtained a Temporary Restraining Order on that afternoon which prevented any further work 

until a court hearing could be conducted. 

The hearing occurred on September 19, 2003, and the property owner was not successful in 

providing adequate evidence to support a permanent injunction to prevent or limit the tree 

trimming activities. Therefore, the case was dismissed by the court. 

Cinergy contractors were able to resume work activities on September 23, 2003 and continued 

until the full Action Plan was completed on October 9, 2003. The property will continue to 

receive annual maintenance attention to ensure that vegetation within the easement does not 

impact the lines operation. 
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Appendix E: Examples of Absolute and Restrictive Easement Rights 

Based on our review of various easement documents, ordinances, and mutual agreements, it 

appears that there is a wide variety of varying, and often conflicting, rights to perform required 

UVM along transmission lines and corridors. The following provides examples. 

Absolute Rights 

The following is language taken from an easement document that describes the rights of the 

utility regarding what can be pruned or removed. It is an example of absolute rights. 

“The easement and rights herein granted shall include the right to erect, inspect, 

operate, replace, relocate, repair, patrol and permanently maintain upon, over, under 

and along the above described right of way across said premises all necessary 

structures, wires, cables and other usual fixtures and appurtenances used for or in 

connection with the transmission and distribution of electric current, including telephone 

and telegraph, and the right to trim, cut, remove or control by any other means at any 

and all times such trees, limbs and underbrush within or adjacent to said right of way as 

may interfere with or endanger said structures, wires or appurtenances, or their 

operations.” 

These rights should be fully enforceable by the utility and should not significantly limit their 

work. 

Restrictive Rights 

The following excerpts taken from the Cleveland Metropolitan Park District easement initially 

appear to provide explicit rights with regard to pruning and removal but, in fact, do not: 

Paragraph 6: 

“The right at all times to trim or cut all or part of any trees within or without the limits of the 

Easement Area in order to maintain at all times a clearance of ten (10) feet between any such 

trees, whether standing or fallen, and the nearest wire of said transmission lines; and further, 

during the period of original construction and during any period thereafter when said wires are 

being reconstructed, repaired, renewed or removed, the right to trim, cut, and remove all trees. 

Branches, and wooded growth to the extent approved by Grantor in writing, except at tower 

sites where an area of minimum dimensions require for the construction, repair, or maintenance 

of the tower, but in no case an area exceeding ninety (90) feet square with its center being the 

coincident with the center of the base of the tower, may be cleared of trees, branches, and 

wooded growth...” 

However, the permit goes on to read in Paragraph 6, Part D, “Specific practices will be adhered 

to as described in Exhibit A attached hereto and made part hereof.” 

In addition to the boilerplate language provided above, Exhibit A describes, in more detail, what 

can and cannot be done on this particular right-of-way. 

Exhibit A: 

“...Cleveland Metroparks staff was especially concerned about the impact of new lines on the 

mature forest. To evaluate the impact, FirstEnergy located the proposed easement in the field 

and Park District staff surveyed the trees within the easement..... From that information, a 

profile of the valley showing each tree and the sag of the new high tension lines was developed. 
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Based on this study, a series of discussions were held on methods to minimize the impact of the 

high voltage line crossing. As a result of these discussions, the following parameters for the new 

lines were developed and have been accepted by FirstEnergy as conditions for granting of the 

relocated easement: 

1. The new and existing easement will be reduced in width from 150 feet to ± 130 feet resulting 

in a net decrease of 0.03 acres in the easement even though the distance of the crossing is 

± 260 feet longer. 

2. There are 81 trees over twelve inches in diameter within the new easement. Approximately 

39 trees will need to be trimmed, and of those, twenty trees will be trimmed twenty feet or 

more. No trees will need to be removed. 

In this example, an easement that started out providing relatively explicit rights has now been 

modified to address concerns of the Park District. On one hand, it illustrates how utility 

companies commonly work with other stakeholders to balance often-competing priorities. On 

the other hand, it illustrates the common practice of reducing the ability and rights of the utility to 

aggressively maintain the vegetation. 
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Appendix F: Ohio Rainfall Data 

 1996 1997 1998 1999 2000 2001 2002 

2003 

(January 

through 

June) 

Akron/Canton 

Rainfall 46.92 32.29 40.28 35.81 45.61 32.90 40.67 19.32 

Normal 36.82 36.82 36.82 36.82 36.82 36.82 36.82 18.82 

Above/Below Normal 10.10 (4.53) 3.46 (1.01) 8.79 (3.92) 3.85 0.50 

Percent of Normal 127% 88% 109% 97% 124% 89% 110% 103%

 

Cleveland 

Rainfall 46.36 35.36 32.82 31.97 30.59 34.36 36.39 19.17 

Normal 36.63 36.63 36.63 36.63 36.63 36.63 36.63 18.47 

Above/Below Normal 9.73 (1.27) (3.81) (4.66) (6.04) (2.27) (0.24) 0.70 

Percent of Normal 127% 97% 90% 87% 84% 94% 99% 104%

 

Mansfield 

Rainfall 53.06 38.86 37.49 34.11 40.48 33.99 37.25 15.78 

Normal 39.66 39.66 39.66 39.66 39.66 39.66 39.66 21.27 

Above/Below Normal 13.40 (0.80) (2.17) (5.55) 0.82 (5.67) (2.41) (5.49)

Percent of Normal 134% 98% 95% 86% 102% 86% 94% 74%

 

Dayton 

Rainfall 54.70 31.23 39.12 29.86 34.33 42.20 37.84 18.62 

Normal 38.66 38.66 38.66 38.66 38.66 38.66 38.66 19.33 

Above/Below Normal 16.04 (7.43) 0.46 (8.80) (4.33) 3.54 (0.82) (0.71)

Percent of Normal 141% 81% 101% 77% 89% 109% 98% 96%

 

Cincinnati 

Rainfall 53.40 40.12 51.39 32.47 45.81 46.58 44.30 19.74 

Normal 41.60 41.60 41.60 41.60 41.60 41.60 41.60 20.80 

Above/Below Normal 11.80 (1.48) 9.79 (9.13) 4.21 4.98 2.70 (1.06)

Percent of Normal 128% 96% 124% 78% 110% 112% 106% 95%

 

Columbus 

Rainfall 45.57 37.96 37.56 27.57 42.85 36.87 39.38 20.28 

Normal 37.62 37.62 37.62 37.62 37.62 37.62 37.62 18.81 

Above/Below Normal 7.95 0.34 (0.06) (10.05) 5.23 (0.75) 1.76 1.47 

Percent of Normal 121% 101% 100% 73% 114% 98% 105% 108%

 

Averages for All Areas 

Rainfall 300.01 215.82 238.66 191.79 239.67 226.90 235.83 112.91 

Normal 230.99 230.99 230.99 230.99 230.99 230.99 230.99 117.50 

Above/Below Normal 69.02 (15.17) 7.67 (39.20) 8.68 (4.09) 4.84 (4.59)

Percent of Normal 130% 93% 103% 83% 104% 98% 102% 96%
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Appendix G: Report by Dr. David Wood, Professor Emeritus, UC Berkeley 

The following report, written by Dr. David Wood, provides technical information regarding how 

precipitation can influence vegetation managed by utility companies. 

Precipitation and Tree Growth 

It is well known that climate has an important influence on tree growth. Numerous tree ring 

studies conducted worldwide have shown that severe droughts are clearly associated with 

depressed growth rates. Twenty-five years of modeling studies have shown water availability is 

the essential driving force in forest productivity. 

Tree ring diameter growth (wood production) is related directly to water availability and 

transpiration. Even when a tree has a healthy crown with high photosynthetic potential, under 

conditions of water stress, diameter expansion will be limited, diameter growth being the first 

sacrifice made by the tree. This is followed by leaf shedding and death of minor and lower 

branches. 

Trees also respond to water stress by stomatal closure, development of the cuticle in leaves, 

and development of deep root systems. As drought periods continue, the lack of available water 

leads to significant stress to trees followed by a potential increase in pest and/or pathogen 

attack. These occurrences can lead directly to decreased tree health and increased tree 

mortality as evidenced by the beetle infestations that have occurred during droughts. 

Different tree species vary in their tolerance to drought. Therefore, some species will be highly 

sensitive to drought effects, whereas others may not. However, all species, whether adapted to 

drought or not, will suffer the effects of a greatly protracted drought. It is very difficult for 

vegetation managers to accurately prepare for the possible effects of drought on tree health 

before the onset of a drought. While it is well known that a lack of available water can cause 

significant harm to trees, the many variables that influence tree growth and health make it 

almost impossible to predict which trees will actually succumb to drought-induced problems. 

For example, the growth of an individual tree is greatly influenced by its relationships with other 

trees growing together in stands. Stated another way, trees growing in a forest setting do not 

grow independently from one another. Competition for light, space and moisture occurs among 

neighboring trees, and the severity of this competition is influenced by distances between trees, 

genetics, crown structure, stand history and management, root structure, and the presence of 

low growing vegetation. 

Roots capture unoccupied space faster than crowns, so understory vegetation can be an 

important factor as well. As discussed above, there are several important effects of drought on 

trees. First, it is well established that periods of drought slow tree growth. Second, periods of 

prolonged or severe drought can greatly weaken trees. Third, trees experiencing stress from 

drought conditions become more susceptible to attack by bark beetles and their fungal 

associates. 

Water relationships in plants are critical to their survival. Plants die when they reach their 

"permanent wilting point." When water loss exceeds water intake, the plant undergoes waterinduced stress. In general, plants exposed to a severe water deficit are more vulnerable to 

insect and microbial attack than plants that receive adequate water. 
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The role of water stress in conifers (the predominant trees in the urban/wildland interface of 

California) and colonization by bark beetles has been studied for several species. Stressed 

trees are killed by bark beetles (and a few other families of beetles) and pathogens. Early 

research on water relations in ponderosa pine was studied in1961 at Grass Valley, California. It 

was demonstrated that the oleoresin exudation pressure (OEP) of ponderosa pines was directly 

related to the loss of water through transpiration in the tree canopy. This critical experiment 

demonstrated that watering the canopy during mid-day (when water loss is greatest from the 

needles) caused an increase in the OEP. Oleoresin is considered to be the tree's key defensive 

mechanism against attack by bark beetles. 

In general, the greater the availability of water to the roots of the tree, and/or the greater the 

reduction of water loss through the needles, the greater the tree's capacity to withstand 

infestation by bark beetles and microorganisms. The relationship of OEP to tree mortality 

caused by the western pine beetle and mountain pine beetle was demonstrated at this time. 

Periods of drought also slow tree growth. Moisture deficits cause fine rootlet mortality. Tree ring 

analyses are used extensively to study rainfall patterns, which have recently provided evidence 

in support of global warming trends. Reduced growth is also caused by high stand density, i.e., 

through competition for water, etc. In general, the higher the density, the slower the growth rates 

of the trees. The slower the growth rates, the more vulnerable they are to bark beetle 

infestation. 

Stand hazard rating systems for bark beetles take into account moisture availability. For 

example, thinning is one of the recommended treatments to lower stand susceptibility to bark 

beetle infestation. Thus, more moisture, light and space are made available to the uncut trees. 

Growth is the biological process of increase in size with time. This process involves converting 

sunlight energy, carbon dioxide, and water to wood and leaf mass, and interacting or adapting 

to temperature, moisture, and nutrient conditions and biological agents. Additionally, tree growth 

rates can be influenced by both tree species and age. Different species grow at different rates. 

Additionally, some species grow rapidly early in their lives, then later slow down, while others 

grow at more constant rates (e.g., eucalyptus vs. Monterey pine. Age and species are therefore 

key variables in the growth equation. 

Just as drought has the effect of suppressing tree growth, an increase in available water 

typically results in increased tree growth. Precipitation can increase baseline growth by as little 

as 10 percent or as much as 300 percent. As previously stated, water availability has, indeed, a 

significant influence on tree growth. The phenomenon of increased tree growth related to 

increased precipitation has been witnessed by forestry professionals and scientists for over 100 

years. 

Water availability is the factor most referred to as having a predominant effect on forest 

productivity. While studies of excessive water on the susceptibility of trees to bark beetle 

infestation are limited, research indicates that fine root biomass is reduced under such 

conditions, with trees having lowered resistance to bark beetle invasion. In the first year 

following the drought, growth would be less than in the second year following the drought. In the 

first year the tree would begin to increase its photosynthetic capacity by adding more needles 

and by adding longer needles. Also, the fine rootlet mass would be increased, facilitating greater 

uptake. 
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Because of the extended drought stored carbohydrates would be very low and the number of 

needles and their size would be greatly reduced. Internode length and year ring width would be 

increased in the years following the end of the drought. Thus, year ring width in the first year 

following the drought would be less than in the second year, but greater than the year ring 

produced during the last year of the drought. Vegetation managers do not have the ability to 

predict how long a drought will last. 
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Appendix H: Sample State UVM Standards and Requirements (Submitted 

October 2003) 

All of the following were answers received from the respective commissions in response to the 

Power System Outage Task Force information requests. 

New York State Public Service Commission

“The New York State Public Service Commission (PSC) supervises the standards for tree 

trimming, foliage management, and ROW clearance management within transmission corridors 

under its Regulations at 16 NYCRR Part 84. That provision sets out the framework for the 

submittal and approval of ROW vegetation management plans (ROW VMP) filed by each 

jurisdictional utility. Specifically, PSC regulations require that every ROW VMP contain 

standards for tree trimming and right-of-way vegetation “management”. While each utility’s 

approved ROW VMP is different in detail, overall they reflect consistent themes for ROW 

management activities, techniques and specifications regarding conductor clearance zones.” 

New Jersey Board of Public Utilities

“The New Jersey Board of Public Utilities (NJBPU) has drafted a proposed rule and is in the 

process of soliciting comments from the public regarding standards for tree trimming, foliage 

management, or right of way clearance management within transmission corridors. Pursuant to 

the Electric Discount and Competition Act of 1999, the New Jersey Board of Public Utilities must 

adopt appropriate standards to assure the continued provision of "high quality, safe and reliable 

service" to electric utility customers in the restructured electric utility environment. Recognizing 

that trees and other vegetation are factors in causing service interruptions, part of an overall 

approach to providing safe and reliable electric service is to maintain trees and other vegetation 

so as to prevent contact with electric facilities.” 

Pennsylvania Public Utilities Commission

“The Pennsylvania Public Utility Commission has not established formal standards for tree 

trimming, foliage management or right of way clearance management within transmission 

corridors. 

However, in August 2002, in response to a Staff Inspection and Maintenance Study, the 

Commission considered whether to prescribe specific inspection and maintenance standards, 

including tree trimming requirements, for electric distribution companies. Although the 

Commission declined to adopt prescriptive standards at that time, it agreed with Staff 

recommendations to establish specific reporting requirements aimed at gathering inspection and 

maintenance information. (Order adopted August 29, 2002 at Docket No. M-00021619.) 

Thereafter, on June 26, 2003, the Commission adopted proposed regulations that contain 

provisions which would require electric distribution companies to submit information on quarterly 

and annual bases regarding the inspection and maintenance of transmission systems, including 

vegetation management, distribution and substation maintenance activity and capital 

improvement projects. The proposed format of this reporting requirement would allow for a 

comparison of the previous year’s inspection and maintenance goals to the actual results 

achieved. For instance, this portion of the report would show the company’s goal for the 

number of transmission line trimming and clearing projects for the year, as well as the number 

of such projects that were actually completed. (Order adopted June 26, 2003 at Docket No. L00030161). 
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Also in the June 26, 2003 Order, the Commission directed the electric distribution companies to 

comply with the proposed regulatory requirements pending finalization. The companies will 

begin submitting quarterly reports to the Commission in November 2003 and annual reports in 

March 2004 that will include documentation of inspection and maintenance goals and expenses, 

as well as staffing levels for transmission and distribution operation and maintenance.” 

Michigan Public Service Commission

“The Michigan PSC has adopted Rules regarding Services Supplied by Electric Utilities. Rule 

505 provides as follow: 

Each utility shall adopt a program of maintaining adequate line clearance through the use of 

industry-recognized guidelines. A line clearance program shall recognize the national electric 

safety code standards that are adopted by reference I R 460.811 et seq. The program shall 

include tree trimming. 

When it was adopted, this rule applied generally to electric transmission and distribution in 

Michigan. However, subsequently almost all transmission has been divested to independent 

transmission companies. The Detroit Edison Company transmission system has been sold to 

the International Transmission Company. Consumers Energy Company’s system was sold to 

Michigan Electric Transmission Company. The various utility transmission systems in 

Michigan’s Upper Peninsula were divested to the American Transmission Company. In addition, 

the Wolverine Power Supply Cooperative owns and operates 1600 miles of transmission in 

western and northern Michigan. Each of these transmission companies is subject to the 

jurisdiction of the Federal Energy Regulatory Commission rather than the Michigan PSC.” 

Ohio Public Utilities Commission

“The Public Utilities Commission of Ohio’s (PUCO) Electric Service and Safety (ESS) Rules 

provide for extensive inspection and reporting requirements by electric distribution utilities in 

Ohio. Under the rules, each utility is required to comply with the National Electrical Safety Code, 

establish a maintenance plan, and regularly inspect transmission lines, distribution lines, and 

substations. In addition, each utility is required to annually report: whether it has met systemwide performance targets, how it plans to address its worst-performing circuits and whether it 

has met maintenance goals. 

Under Ohio Administrative Code (OAC) rules 4901:1-10-26 and 4901:1-10-27, the PUCO 

requires each utility that owns transmission in Ohio to file with the PUCO a formal report on its 

methodology to assess the reliability of its transmission and distribution circuits and equipment. 

The companies filed their first reports in January 2001. PUCO staff reviewed the methodologies 

with each company, either accepting the methodology or recommending changes. Right-of-way 

vegetation control was explicitly mentioned within the scope of this requirement. 

In March 2001, each company submitted a report to PUCO staff detailing its methodology used 

to assess the reliability of its transmission circuits for review and acceptance. OAC rules 4901:1-

10-27 (C) and (D) require each utility to file a transmission system performance assessment 

report by March 1 of each year, beginning March 2002. OAC rule 4901:1-10-27 (C)(2) requires 

each company to file annually a report that identifies the performance of each transmission 

circuit for the previous year. OAC rule 4901:1-10-27 (D)(4) requires each company to file 

annually a report on its compliance with the following inspection schedule for transmission lines 

and substations: 

• All transmission circuits and equipment shall be inspected at least once every year. 
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• All transmission and distribution substations and equipment shall be inspected at least 

once each month. 

OAC rule 4901:1-10-27 (C)(2) requires at a minimum the following information be provided for 

each transmission circuit in the annual report: 

a) Circuit identification number 

b) Location of each circuit 

c) Number of outages and their causes by circuit 

d) Substation(s) and /or distribution circuit(s) affected by each outage 

e) Remedial action taken or planned 

f) Start and completion dates of any remedial action taken or planned 

All the companies have marked this transmission outage data as confidential.” 

Massachusetts Department of Telecommunications and Energy

“The Massachusetts Department of Telecommunications and Energy (DTE), a public utility 

commission, has evaluated electric companies tree trimming and foliage management plans 

and practices on numerous occasions in the past 10 years and continues to evaluate them on 

an on-going basis. 

Regulated companies are required to file storm preparation plans annually, which include 

foliage management plans as part of pre-storm preventive maintenance. In addition, the 

companies are required to file tree trimming schedules with the DTE on a quarterly basis as part 

of their service quality reporting requirements. 

Additionally, as part of service quality assessments, the companies are required to file tree 

trimming policies, including cycles, inspection procedures, and typical minimum vegetation 

clearance requirements as well as budget information (including funds expended for tree 

trimming in the past ten years). 

The participants of the New England Power Pool (NEPOOL), which include the Massachusetts 

electric companies, have adopted a standard for vegetation management of transmission rightof-ways. (See Attachment A, NEPOOL Vegetation Management Standard). 

Based on our review of the company filings to the DTE and the NEPOOL standards, the DTE 

has not found reason as yet to adopt any formal universal standards beyond the current 

company-specific guidelines and the NEPOOL standards implemented by the companies. 

Furthermore, most of the transmission systems are located in relatively large right-of-ways, 

which give the companies approximately 30-feet of access to the infrastructure, i.e., no treetrimming permission from the community or property owner is typically required. This way the 

companies are allowed to do clear cutting, which could provides substantially more clearance 

than the requirements established in the above-mentioned NEPOOL standard.” 

Connecticut Department of Public Utility Control

“The Department does have standards and filing requirements related to distribution vegetation 

management; however, it has the belief that transmission vegetation management is subject to 

FERC jurisdiction, the Independent Systems Operator of New England (ISO-NE), and therefore 

state commissions are precluded by federal pre-emption from asserting jurisdiction over these 

matters.” 
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Vermont Public Service Board

“Formal standards for vegetative management are specified in Vermont Public Service Board 

Rule 3.600. Please see http://www.state.vt.us/psb/rules/3600_ROW.pdf The following are 

excerpts from Rule 3.600:” 
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Appendix I: Engineering Assumptions 

As explained in various parts of this report, the initial tree contacts (and subsequent outages) 

were more an issue of tree growth, as opposed to line sag. To supplement this finding, we 

performed a review of the specific practices at AEP, FE, and Cinergy in order to assess their 

procedures, practices, and assumptions related to this important engineering consideration. The 

following represents the findings of this effort. 

ANALYSIS OF ASSUMPTIONS USED FOR LINE RATINGS, LINE SAG, AND LINE 

CLEARANCE 

The following table is a comparison of the assumptions used by FirstEnergy (FE), Cinergy, 

American Electric Power (AEP), and by the industry at large for line ratings, line sag, and line 

clearances48. 

In general, the three utilities analyzed employed transmission line rating, sag, and clearance 

procedures that are in line with the electric utility industry at large. The assumptions that they 

use in these procedures are also generally in line with the industry at large. 

Specific areas of concern are included in the appropriate sections of the UVM Program 

Assessments. 

 

48 Review prepared by William S. Gray Jr., P.E. 
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DETAILED ENGINEERING RESPONSES 

# Review Questions FE Cinergy AEP 

 LINE RATINGS 1. Are there State codes 

or regulations that govern transmission line ampacity ratings? 

Yes, The Ohio 

Administrative Code 

(4901:1-10-06) 

mandates 

compliance with 

NESC 

NESC Yes, Ohio mandates 

compliance with NESC 

Y

2. Do you have Company 

standards that specify transmission line ampacity? 

Yes Yes, “Conductor and 

Equipment Rating 

Guide” attached 

Yes, “A Guide for 

Maximum 

Temperature And 

Ampacity of Bare 

Overhead 

Conductors”

3. Do your Company 

standards regarding line ratings comply with the State codes or regs? 

Yes Yes Yes 

4. Have you done any 

benchmarking to determine the best practices with regard to assigning ampacity ratings to overhead transmission lines? 

No Informal 

comparisons with 

other utilities 

No 

5. Do you participate in 

industry organizations such as IEEE, EEI, ANSI, or CIGRE? 

Yes, IEEE, ASTM, 

AEIC, and Ohio 

Electric Utility 

Institute 

IEEE Insulated 

Conductors 

Committee, ASCE 

Structure Loading 

Committee 

ANSI, ASCE, EEI, 

IEE, and EPRI 

Y
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# Review Questions FE Cinergy AEP 

6. Do you follow industry 

organization working committees’ recommendations regarding transmission line ratings? 

Yes, ECAR, NERC, 

and MISO 

Yes, IEEE 738-1993 Yes, industry codes, 

standards, 

guidelines, and 

operating 

experience 

7. Do your Company 

standards regarding line ratings conform to IEEE 738-1993? 

Yes, ECAR Guide 

68-TAP-28 is the 

same as IEEE 738 

Yes Yes 

8. Do your Company 

standards regarding line ratings conform to manufacturers’ recommendations? 

Yes, manufacturers’ 

ratings are not 

exceeded 

Yes Yes 

9. Are your transmission 

line ratings adjusted for: 

See footnote 49

9a Seasonal 

variations in temperature 

Yes Yes, summer and 

winter ratings are 

applied 

Yes, summer and winter 

normal and emergency 

ratings are applied 

9b Wind velocity Yes No, 2 mph used 

everywhere. 

No, 2 mph used 

everywhere. 

49 Wind velocity and ambient temperature play a dominant role in determining transmission line loadability. Reasonably conservative va

winter, 2.1 mph summer and 1.3 mph winter) have been chosen to determine loadabilities for planning studies, however loadability levelambient conditions being experienced in actual operation of the transmission system. In addition, the wind direction azimuth is assumed conductor. Solar radiation effect is also used, the sun chosen for summer ratings is July 3 (1400 hours) and no sun for winter. 50 On a case-by-case basis, following detailed inspection of the line. With approval of Transmission Department Manager lines may be r

speed rather than the standard 2 fps. 
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# Review Questions FE Cinergy AEP 

9c Elevation? No, rather than adjust 

for the elevation for 

each line section a 

1000 ft. elevation is 

assumed for use in 

the ECAR Guide 68-

TAP-28 and IEEE 

738-1993. 

No, an elevation of 

500 feet is used for 

all ratings 

No 

10. Are emergency, or 

short-time overload, ratings assigned? 

Yes, using 

parameters that 

correlate to a 5% risk 

No Yes, emergency ratings 

are a long-term 

continuous load rating 

based upon loss of life of 

the facility. Under certain 

contingencies 115% of 

emergency ratings may 

be used depending on 

real time conditions. 

Y

1

11. Do you employ any 

sort of dynamic thermal rating? 

No, piloting device 

from the Valley 

Group 

No No 

12. If dynamic ratings are 

assigned: 

12a What are the 

ratings 

Not assigning during 

pilot 

N/A N/A 

12b What variables are 

monitored 

Tension, wind speed, 

and ambient 

temperature 

N/A N/A S
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# Review Questions FE Cinergy AEP 

12c How are they 

monitored and recorded? 

Processed in a local 

device and 

transmitted to the 

control center 

N/A N/A 

r

13. Are transmission line 

ampacities de-rated to account for conductor age, possible annealing, or the number, age, or condition of splices? 

Occasional 

temporary de-rating 

until abnormal 

conditions are 

corrected 

Clearances, 

annealing, and line 

equipment are 

considered in line 

rating. Age is not. 

Ratings are based on an 

anticipated 50-year 

annealing 

Y

n

c

14. May we have copies of 

all documents your Company uses pertaining to the ampacity rating of overhead transmission lines?51

Yes, attached52 Yes, attached53 Yes, attached54 

51 Each utility was also asked, “For each 138kV and 345kV line, please provide the line length; conductor type; size and number of cond

service date; and line design parameters, including tower/pole type, average span, and design tension and sag. Also indicate the date thfor sag and tension and what he findings were.” They were also asked, “Please explain the basis for ambient temperature and wind spe

rating your transmission lines.” 52 Line length, conductor size, conductor type, conductors per phase, tower/pole type, and average span are attached. Insufficient time 

sag, in-service dates, and inspection data. Wind and temperature were based on 27-year data from the National Weather Service. Temexceeded twice a year on average, and wind speed 1% of the time. 53 Data from FERC Form 1 attached. Insufficient time to gather the additional requested data. FERC data also supplied for 230kV. No 

and tension, just routine inspections. Ambient temperatures based on review of typical hot summer temperatures and compared with oth

assumptions not verified but compared with other utilities. 54 GIS data is attached, however the accuracy of the conductor information has not been verified. Temperatures and wind speed chosen summer and winter assumptions. 55 N/A for 138kV and 345kV lines. Ambient temperatures are based on thirty-year data from the National Weather Service. 
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# Review Questions FE Cinergy AEP 

 LINE SAG 1. Do you have Company 

standards that specify transmission line sag? 

No, NESC is applied No, NESC is applied Yes, attached 

2. What is the design 

basis for sagging your transmission lines: 

2a Company 

standards 

No Yes Yes 

2b Manufacturers’ 

recommendations 

No Yes ALCOA Sag and Tension 

Program, Stress/strain 

relationships are 

obtained from other 

manufacturers 

2c NESC Yes Yes Yes 2d Utility best 

practices 

No Yes No 

2e Industry standards Yes, IEEE P-524 Yes No 2f Other? None None None 3. Do your Company 

standards regarding transmission line sag conform to IEEE P-524 — “Guide to the Installation of OH Transmission Line Conductors?” 

Yes Generally, yes Generally in line with the 

general procedures 

4. Do your Company 

standards regarding transmission line sag conform to the National Electric Safety Code? 

Yes Yes Yes 
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# Review Questions FE Cinergy AEP 

5. Are transmission line 

sags checked during stringing? 

Yes Yes Yes 

6. Do you ever re-use a 

previously installed conductor? If so, are tensions adjusted during stringing? 

Yes, existing 

conductors are 

transferred to new 

structures. Tensions 

are readjusted. 

No Rarely 

If done consideration is 

given to adjusting final 

sags 

7. Is the weighted average 

span length used for calculations, or some approximation? 

Weighted average, 

except very old lines 

used simple average.

Ruling span 

calculations with sag 

charts 

Not in current design, but 

may have been used in 

the past 

8. How are ruling spans 

calculated? 

Depending on the 

age of the line: 

• Simple 

average 

• Average span 

+ 2/3(longest span – shortest span)

• Weighted 

average 

Computer program 

using weighted 

average 

Weighted average 

9. Are transmission line 

sags adjusted for temperature districts and loading districts? 

No temperature 

districts. Entire 

system designed for 

NESC Heavy LD 

NESC loading criteria NESC loading criteria are 

met or exceeded 

10. How do your conductor 

stringing procedures account for initial and final temperatures? 

Sag tables Initial: typically 

normal ambient 

Final: worst case sag with ice or at 

maximum operating 

temperature. 

Initially sagged so as to 

meet final clearance sag 

and temperature 

In

F

56 Ruling span is determined using the weighted average span length: Ruling Span = [(S13 + S23 + +S33 ....... +Sn3)/(S1 = S2 + S3 ........ S
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# Review Questions FE Cinergy AEP 

11. How do your conductor 

stringing procedures account for conductor creep? 

Computer sag 

tension program 

Creep is typically 

neglected. If it is 

determined to be a 

factor, manufacturer’s 

installation guide is 

used to modify the 

sag charts. 

High temperature creep 

is incorporated in the sag 

and tension computer 

program. 

12. May we have copies of 

all documents your Company uses pertaining to the sagging of overhead transmission lines? 

Sample documents 

attached 

Work practice for 

sagging conductors is 

attached 

General Specifications 

for T&D Construction and 

the ALCOA (modified) 

Sag and Tension 

Program are attached 
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# Review Questions FE Cinergy AEP 

 LINE CLEARANCES 1. Are there State codes 

or regulations that govern transmission line electrical clearances? 

Yes, The Ohio 

Administrative Code 

(4901:1-10-06) 

mandates compliance 

with NESC 

NESC NESC 

C

2. Do you have Company 

standards that specify transmission line electrical clearances? 

NESC, OSHA, FAA, 

Army Corps of 

Engineers, Railroads 

Clearance drawings 

based on NESC are 

attached 

Yes57 

3. Do your Company 

standards regarding line clearances comply with the State codes or regulations? 

Yes Yes Yes 

4. Have you done any 

benchmarking to determine the best practices of other utilities with regard to assigning electrical clearances to overhead transmission lines? 

No No No 

5. Do you participate in 

industry organizations such as IEEE, EEI, ANSI, or CIGRE? 

EEI, ASTM, AEIC, 

and Ohio Electric 

Utility Institute 

IEEE Insulated 

Conductor 

Committee, ASCE 

Structure Loading 

Committee 

ANSI, ASCE, EEI, 

IEE, and EPRI 

Y

W

57 “System Standards – Transmission and Substransmission Lines, Clearances, Mechanical Loadings and Overload Factors Applicable 

Hardware, Insulators, Conductors, Groundwires and Line Design” and “Guidelines for Review of Certain Transmission and SubstransmisPrior to June l, 1978 or the 1977 edition of the NESC for Operation at Conductor Temperatures above 120° Fahrenheit” are attached. 
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# Review Questions FE Cinergy AEP 

6. Do you follow industry 

organization working committees’ recommendations regarding transmission line electrical clearances? 

No, NESC, OSHA, 

FAA, Army Corps of 

Engineers, Railroads 

NESC No, but company 

standards are based on 

NESC 

7. If emergency, or shorttime overload, 

ampacity ratings are used, are less-thanminimum clearances accepted for these short duration periods? 

No No, electrical 

clearances are not 

reduced during 

contingency 

operation. 

No 

g

8. What swing buffers are 

specified in your clearance standards? 

Horizontal clearances 

meet or exceed NESC 

and OSHA 

NESC 

Calculations 

included in the 

clearance standard 

NESC and company 

standards 

10

9. How frequently are 

your overhead transmission lines inspected for adequate clearances? 

6-months 4-months Aerial patrols annually 

and foot patrols as 

needed 

Ae

G

d

crit
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# Review Questions FE Cinergy AEP 

10. How are temperature 

variations accounted for during transmission line inspections? 

Inspectors are given a 

work aid illustrating 

required clearance 

adjustments for 

ambient conditions 

 Ambient 

temperature and 

anticipated load are 

factored in when 

inspecting 

Wind speed, ambient 

temperature and other 

relevant weather 

conditions as well as the 

relative conductor 

position are used in an engineering evaluation 

of the line 

In

11. May we have copies of 

all documents your Company uses pertaining to the electrical clearances of overhead transmission lines? 

Refer to codes and 

regulations listed 

above. Tables from 

Company Standards 

are attached. 

Clearance Drawings 

attached 

Yes 
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Appendix J: Industry Recommendations 

In this appendix, we are providing the written responses of our expert panel to the posed 

question: 

“As an industry expert, what would you recommend needs to be changed, improved, or 

fixed in order to reduce or prevent the likelihood of future tree and transmission line 

conflicts?” 

Once again, these commentaries do not necessarily reflect the opinions of the companies or 

organizations that these individuals work for. They are simply the thoughts of the individual 

experts. 

MR. ROBERT W. BELL, Pacific Gas & Electric Company, President of the Utility Arborist 

Association (California) 

“The Rule of Law.” In over a decade of troubled times, that phrase has moved to the forefront of 

political speech. The media reports on legal issues of all types with great fervor. Government 

entities, corporations and individuals all take the law very seriously; as well we should. While 

individuals may disagree over one law or another, no reasonable person would suggest that 

anarchy is preferable to a lawful society... or would they? 

If social anarchy is when a society decides to ignore the laws of government, what is it when a 

government, corporation or individual decides to ignore the laws of science? I don’t know if 

there is a name for it, but the results are well documented. In terms of the electric utility 

industry, those results have included several catastrophic wildfires, three electrical grid failures 

since 1996, numerous smaller wild land and structure fires, and millions of cases of interrupted 

electrical service to individual customers and businesses. 

Electricity seeks the ground. This is a law of physics. It can’t be vetoed or legislated away. 

Trees grow up. This is a law of nature. You can’t negotiate with nature. The only time a tree 

stops growing is when it is dead... and there is usually another tree waiting to take its place. 

Fortunately, from an electric reliability standpoint, trees are pretty easy to kill. Unfortunately, the 

vegetation manager at a typical utility company faces many man-made obstacles between the 

teeth of the chainsaw and the trunk of the tree. 

In my opinion the single most inhibiting obstacle is government bureaucracy and regulations 

that conflict with the laws of science. It is also the obstacle that could most easily be cast aside 

if the governments with the power to do so have the will to do so. 

It is inconceivable to me that a municipal parks department, a state transportation department, 

the US Forest Service or any other similar entity should have the final authority over a utility 

company managing vegetation in proximity to high-voltage transmission lines, but they do. In 

fact, any of these and many other local, state and federal government agents have the power to 

stop a utility crew in its tracks. Although more often than not, the utility is stopped before it can 

even start by a never-ending gauntlet of burdensome, inconsistent, often conflicting rules, 

regulations and bureaucracy. While people finger-point and litigate, the trees keep growing. 

There are many utility facilities that cross public and private lands. At the very least, we need to 

begin looking at those corridors critical to the integrity of the electrical grid in a different way. In 
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the interest of national security, public safety and the North American economy, I propose that 

the U.S. and Canadian governments consolidate the authority over transmission line corridors in 

their respective territory and give that authority to the U.S. Department of Energy and its 

Canadian equivalent. The amount of land in question is miniscule compared to the total 

holdings of agencies such as the U.S. Departments of Agriculture and Interior. But the 

implications of mismanagement are enormous to the integrity of the electrical grid. 

As a corollary to this proposal, we must recognize that it only takes one tree to trigger a 

catastrophic grid failure. That tree might be on private property. Utility companies must have 

the authority to do whatever they deem necessary, based on the laws of science, to protect 

critical electric transmission facilities on private as well as public lands. 

Mr. Bell is a Sr. Vegetation Program Manager for the Pacific Gas and Electric 

Company. He has a B.S. degree in forest science from The Pennsylvania State 

University and an M.B.A. from the University of New Mexico. He is a Certified 

Arborist and a Certified Utility Specialist through the International Society of 

Arboriculture. In his career, Mr. Bell has worked for municipal and investor owned 

utility companies throughout the United States and Canada. 

Mr. Bell is the President of the Utility Arborist Association. He is past president of 

the Missouri Community Forestry Council; a past director of the Midwest Chapter 

of the International Society of Arboriculture; and past president of Think Trees 

New Mexico. 

MR. RICHARD E. DEARMAN, Manager of System Applied Maintenance, TVA (Alabama) 

(Note: Mr. Dearman did not participate in the development of the BMPs but was asked to 

provide his expert commentary for this section.) 

We in the transmission industry must provide better information to the general public, local, 

state and federal entities, and property owners about the fundamental differences between 

vegetation management for grid lines and non-grid lines. The transmission industry’s current 

vegetation management practices on grid lines must change significantly based on these 

fundamental differences. 

Definitions: 

Grid lines - those lines that connect transmission buses thereby providing network load flows or 

directly connect generation to the transmission grid. 

Non-Grid lines - All radial lines that feed loads only, including any radially tapped sections of 

grid lines capable of automatic separation from that grid line without opening the grid flow path. 

Critical differences in interruptions on Grid and Non-Grid lines: 

When non-grid lines experience interruptions, the load requirement on the grid is reduced. In 

fact the strength of the grid is increased after the short term surge passes. In this scenario the 

available generation and grid capacity is the same with reduced load requirements. The chance 

of a widespread blackout is less than before the load interruption. 

When grid lines experience interruptions, the load requirement on the grid is not reduced. All 

loads are still connected, and the currents shift to supply the loads through the remaining wires. 
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The wires and other grid components will now have more current through them. These 

increased currents result in increased conductor sags, lower voltages, increased generation 

needs for reactive and real power, and lower grid reliability. The cascading blackout event 

begins with such a scenario! 

What the transmission industry must do: 

We must communicate the above differences internally and externally. 

Internally we must change our programs, culture and practices that relate to vegetation 

management to fully reflect the higher standard of care required for grid lines. Currently 

programs for tree pruning, tree trimming, low growing species, buffer zones, border zones, etc. 

are embedded within the total vegetation management approach. While such programs are 

appropriate on non-grid lines they should be avoided on grid lines. 

Grid line easements should be maintained with no woody species allowed anywhere on the right 

of way. Time for identification of desirable versus undesirable species, rates of growth, effective 

herbicide usage, etc., would be drastically reduced if these approaches were taken, and no 

undergrowth tree would place a grid line at risk because of “special” conditions or agreements. 

Externally, after informing other stakeholders of this higher standard of care, we must work with 

them to gain their support for implementation of this approach. Numerous ordinances, 

regulations, and laws related to beautification, environmental and special interests will need to 

be addressed. Our duty in the operation and maintenance of the transmission grid is to ensure 

that the interest in a reliable be grid not be reduced by interests of lesser value to society. 

Disclaimer: The views are those of this author and his opinion as to a desirable ideal. They do 

not reflect the status of any program currently in use at TVA. 

Mr. Dearman is the Manager of System Applied Maintenance in TVA’s 

Transmission Operations and Maintenance Department of the Transmission 

Power Supply Group. In that capacity he is responsible for TVA's vegetation 

maintenance activities. Mr. Dearman has over 32 years experience in electric 

utility operations, engineering, and management. His experience includes 

responsibilities for vegetation management at the distribution and transmission 

level for 21 years. Mr. Dearman is a registered P.E. in the state of Mississippi. 

Mr. Dearman also provided invaluable assistance during the field investigation 

phase of this UVM project. 

MR. SCOTT DEEVERS, Business Manager, The Davey Tree Expert Company (Ohio) 

Management Keys to a Best Practices Vegetation Management Program 

More than ever, the public and state and federal governments are demanding better reliability in 

the transmission of electrical service. As a result, increased attention is being directed toward 

tree and vegetation management programs as being a major part of the solution. At the same 

time, industry reports and independent research have indicated that most utilities have 

systematically reduced their maintenance budgets in this critical area as pressures from 

deregulation and the investment community mount. 
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Understanding and addressing three critical areas within a program will determine the 

probability of a utility’s success in this area. 

Stability

The first component of successful vegetation management programs relates to the stability of 

the program itself. The most stable programs in the industry are normally those that have 

reduced problems with electric transmission. In general, programs with stable internal 

management, consistent spending patterns and stability in those performing the work are 

successful. Rapid and frequent changes in any of the three areas noted above will cause 

confusion and reductions in work being completed properly. Industry-wide, the more stable the 

program, the less likely a utility is to have tree-line conflicts that impact customers. 

Buying Practices

The actual role of contractor evaluation and contract award has traditionally fallen to the 

internal program managers. However, recent years have seen more involvement by 

purchasing or “supply-chain management” departments. The assumption made by most 

purchasing departments is that the lowest price is the correct one for the utility. Scores of 

utilities have been negatively impacted by this selection process when the low-price bidder is 

incapable of delivering the service required or, in a number of instances, simply goes out of 

business before completing the contract. This leaves large gaps in work completion at 

scheduled intervals creating more potential power interruption. 

Program Integrity

Unfortunately, even the most stable programs that have carefully evaluated their buying 

practices can experience vegetation problems if integrity within the program does not exist. 

Integrity gaps can kill well-conceived programs by providing incomplete or incorrect data on 

which key decisions are made and can occur from both internal and external sources. 

Maintaining integrity in specification adherence becomes more difficult the larger a program 

gets. Each local manager of a forestry department may have a different interpretation of what 

the specification is which may lead to shortfalls in work efficacy. Depending on who is 

approving the work (and in some situations it is the contractor themselves), this lowering of the 

specification can have a substantial negative impact. The most successful programs 

consistently apply the specifications set forth and audit the work for appropriate completion. 

Mr. Deevers has been an active participant in the utility vegetation management 

industry for seven years. He has been responsible for the evaluation of dozens 

of vegetation management programs for the Davey Tree Expert Company during 

that time. 

Davey Tree is a world-leader in utility vegetation management and has been 

working with utilities since the 1920’s. Currently, Davey Tree works with over 

100 of North America’s leading utility companies to maintain vegetation, assess 

program performance and improve reliability through responsible tree pruning. 

Mr. Deevers is currently the Business Manager for Davey Tree’s utility services 

division and is responsible for monitoring performance of utility operations in the 

Eastern United States. 
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MR. KEVIN K. ECKERT, President and Managing Director, Arbor Global (Hawaii) 

How to Reasonably Avoid Electric Transmission Line-Tree Conflicts 

How do utilities manage trees and vegetation to reasonably eliminate significant conflicts with 

the overhead electric system? Extensive experience and observations of utilities across the US 

and throughout the Pacific Rim have unequivocally demonstrated that the primary factors that 

impact a utility’s ability to provide a reasonable level of electric system reliability, safety and cost 

containment performance relative to tree and vegetation conflicts are the following: 

 

 Utilization of qualified, experienced, responsive arborists to design and administer the 

program; 

 Utilization of state-of-the-art, best management practices; 

 Comprehensive, accurate, up-to-date and accessible workload database; 

 Adequate management support and funding of the program; and 

 Public education of the need and importance of the tree and vegetation management 

program. 

The single most important component of an effective, efficient program is the utilization of 

qualified, experienced, responsive arborists with the authority and resources to design and 

administer the program. To be effective, these arborists must be either utility employees or third 

party contractors not associated with a contractor providing tree and vegetation clearing 

services. Tree and vegetation management is a highly technical specialty that requires an 

appropriate level of education, training and experience to effectively understand and control 

trees and vegetation. Utilization of a qualified, experienced arborist as the responsible manager 

ensures an understanding of how trees grow and respond to various management techniques 

and knowledge of the operational characteristics and requirements of best management 

practices. Many utilities use non-arborist staff as tree and vegetation managers (engineers, line 

supervisors, etc.). These professionals may be very competent within their area of education 

and experience, but have little or no formal education, professional training or experience in 

arboriculture or vegetation management. The use of non-arborists as the responsible manager 

has been demonstrated to frustrate the effective design and administration of programs often 

resulting in unreasonably high levels of tree-related outages, safety hazards, excessive costs 

and customer complaints. 

Decisions, practices and methods utilized for tree pruning, removal and vegetation management 

must be based on state-of-the-art, best management practices consistent with those prescribed 

by the International Society of Arboriculture, Utility Arborist Association and appropriate ANSI 

standards. The use of these work practices must be contractually required and consistently 

enforced. Programs that do not require or enforce the use of proper, technically proven best 

management practices, regularly encounter unnecessary reliability, safety hazards, cost 

expenditure and customer complaint challenges. 

In order to effectively and efficiently plan, schedule and administer any program, it is critical that 

the responsible manager possess a comprehensive, accurate, up-to-date and accessible 

database describing workload size, location and condition. Many utilities rely primarily on 

historical experience, staff knowledge/memory, and/or inadequate records and systems to 

develop and execute their work plans. Programs without an accurate, current workload 

database within an accessible work management system cannot be reasonably expected to 
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cost-effectively identify, monitor and schedule work that will reasonably prevent tree and 

vegetation conflicts. 

Adequate management support for programs and funding is critical to ensure that the utility’s 

tree and vegetation management professionals have the financial resources and internal and 

external political support to conduct the program required to accomplish its service reliability, 

safety, cost-containment and customer satisfaction goals. Without adequate resources and 

executive support, no program will succeed. 

Finally, a well designed and positioned, public education program that regularly and effectively 

reaches the key constituency and stakeholders is crucial to ensure understanding, acceptance 

and support for the program. The need and value of utility tree and vegetation management 

programs are very often misunderstood by other professionals and the public. This 

misunderstanding often results in resistance, and sometimes adverse legislative and legal 

actions, that prevent implementation of the program. It is critical to develop and execute a 

technically based, professionally managed program first, but then get the word out so that all 

those who are involved and affected by the program have the information and understanding 

required to accept and appreciate required pruning and removal work as appropriate and 

ultimately avoid tree conflicts when designing for and planting trees. 

Mr. Eckert is President and Managing Director of Arbor Global LLC providing 

arboriculture and vegetation management consulting services to clients within 

Hawaii, the mainland United States, the Pacific Rim, and Asia. 

Kevin has been a practicing utility arborist for over 20 years developing and 

administering demonstrably successful tree and vegetation management 

programs in temperate and tropical regions. During this period he has also 

provided expert consulting assistance to government agencies, environmental 

organizations, private businesses, and individuals on multiple aspects of 

arboriculture and vegetation management. Kevin is an active educator in the field 

of arboriculture regularly preparing and presenting informational and educational 

programs for professional and civic organizations, corporate executives, and 

managers on numerous arboricultural and integrated vegetation management 

topics. Kevin has published numerous articles in popular and industry publications, 

including the International Society of Arboriculture (ISA) Journal of Arboriculture.

Kevin is a graduate of West Virginia University with a BS in Forestry and a BS in 

Park Management. He is past President of the Utility Arborist Association, former 

Chair of the EEI Vegetation Management Task Force, Chair of the Hawaii Urban 

and Community Forestry Program, Chair of the Western Chapter ISA Arborist 

Certification Committee, and an active member of the Aloha Arborists Association. 

In Birmingham, England, he was awarded the Utility Arborist Award by the ISA 

Utility Arborist Association for contributions to the field of utility arboriculture. 
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MR. BRIAN FISHER, Strategic Coordinator, BC Hydro and Power Authority (British 

Columbia, Canada) 

(Note: Mr. Fisher did not participate in the development of the BMPs but was asked to provide 

his expert commentary for this section.) 

There are, in my opinion, four factors or avoidances that lead to catastrophic tree and power line 

conflicts. 

1. The failure to recognize and fund best practices for Vegetation Management within the 

Utility industry. Twenty years ago, there were very few vegetation experts working for 

Utilities. Vegetation was treated as an item to use to balance the maintenance budget. 

There was little understanding of how trees grow and what practices were necessary to 

mitigate the problematic interface of trees and power lines. Today, there are many 

vegetation experts employed by Utilities and there is a strong Utility Arborist Association as 

an arm of the International Society of Arboriculture; which can offer a huge level of support 

to the industry. Nonetheless, most Utilities are directed by accountants and by engineers 

who are focused on one-time solutions and cost reductions. There is little understanding of 

the diverse nature of vegetation and the need for ongoing professional programs to deal 

with a myriad of terrains, growth rates, species and climatic conditions. Ongoing, consistent 

and adequate funding utilized in an integrated fashion by professional vegetation managers 

is still the greatest need in the world of Utility Vegetation Management. Interestingly, those 

utilities that follow this route generally end up with more efficacious programs at lower costs. 

2. Edge trees: Most tree /power line contacts occur when trees fall onto lines from outside the 

Rights of Ways or corridors. Many utilities are slow to act to address this issue due to the 

perception of increased costs and the pressure from landowners etc. to leave trees 

standing. 

 

 We have laws that forbid people from maintaining unsafe conditions on their property. We 

need legislation that makes it unlawful to maintain or cultivate any tree that is hazardous or 

which may come in contact with a power line within 1.5 tree lengths of a power line and 

authority for utilities to remove unsafe trees without fear of lawsuits or reprisals. I think it 

reasonable to oblige the Utility to locate, identify and prioritize the trees for removal and to 

cover the cost of the removal. We need authority, however, to remove these hazards 

without additional costs or undue delays. 

3. We (Utilities) tend to capitulate in the face of public or agency or municipal pressures. This is 

not good risk management. Vegetation / Power line contact creates a severe public safety 

hazard and a high fire potential. The mandates of other agencies cannot be ignored, but, 

they should also not override utility responsibilities and needs. Utilities have the "duty of 

Utmost Care" to protect the public from contact with power (dangerous thing). If agencies 

and municipalities are to be permitted to refuse consent to or seek compensation from 

utilities for the removal of hazardous vegetation, they should be obliged to assume the 

liability associated with that risk. Whoever bears the responsibility should have the 

unfettered right to mitigate the situation. 

4. As the need for delivery of electricity increases, transmission lines are being utilized at 

levels, which are within engineering tolerances, but far beyond anything intended or 
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anticipated when the lines were built. Transmission lines under heavy load on hot days can 

bring the line sag down to a point where electricity could arc to very low vegetation and 

certainly to a height where work within the area would be unsafe. Every utility should be 

obliged to identify all areas with "Unusual Terrain features" or "Inadequate Engineered Line 

Height". With mitigative action to ensure that at maximum line sag, there was still a 

minimum of 25 feet (7.5 meters) conductor to ground; Vegetation management best 

practices would be able to avoid many hazardous situations. Line Sag is a major factor and 

Vegetation managers need to know what clearances (conductor to ground) will be available 

with maximum line sag. Two tree incidents in the California blackouts were a result of lines 

sagging into trees rather than trees growing into lines.

Mr. Fisher (B.A.) is Strategic Coordinator of Vegetation Management for BC 

Hydro and Power Authority. He is responsible for Vegetation Management 

programs within the corporation. Brian has nearly 30 years experience in the 

Arboricultural Industry -12 in Utility Arboriculture. He has been a Certified Arborist 

for 18 years. Brian has served as a member of both the Certified Arborist and 

Utility Specialist Test Committees of the International Society of Arboriculture. He 

was instrumental in the development of BC Hydro's current vegetation 

maintenance program that benchmarks very well in comparison to other utilities. 

He also developed BC Hydro's Hazard Tree Program designed to target 

hazardous trees outside of the Utility Corridors. 

He is a frequent presenter at training conferences and seminars particularly with 

respect to Utility Arboriculture. Recent presentations include International Society 

of Arboriculture Annual Conference and National Arbor Day Foundation Trees 

and Utilities Conference. 

Brian is currently the Vice President of the Utility Arborist Association. 

MR. JOHN W. GOODFELLOW (Redmond, Washington)

1. The risk profiles of all lines within the transmission network are not equal. 

A one-size-fits-all approach to vegetation maintenance produces sub-optimal results. To 

optimize effectiveness and cost-efficiency, maintenance intensity needs to be based on a clear 

understanding of the criticality of individual lines to the over-all grid. 

Clearing right of way (ROW) to widths sufficient that no tree failure will result in conductor 

contact is not practical in many cases. 

Edge trees and off ROW trees are legitimately recognized as a discrete population of trees 

requiring specific management. Knowledge of tree failures and mortality should be included in 

developing optimal maintenance practices to mitigate the risk to reliability posed by such 

“hazard” or “danger” trees. 

 

2. On-condition, reliability-driven, site-specific vegetation maintenance prescriptions 

need to be used in completing the work. 

 

It must be recognized that, unlike an assessment of the structural and electrical elements of 

infrastructure, vegetation management is focused on a biological system. As such, 
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contemporary vegetation management practices are carried out in a dynamic environment. 

Biological systems respond to “disturbance” (such as maintenance work) in unique but often 

predictable ways. Maintenance work based on an assessment of site-specific conditions and on 

an understanding of the response of vegetation to such work will yield the best results. An 

engineering-based assessment of vegetation and subsequent vegetation “clearing” work based 

on the assumption that trees are simply a problem to be controlled will be less effective and has 

the potential to create future reliability problems. 

3. Clear and complete rights to perform vegetation maintenance work need to be 

established and exercised. 

Too often a utility’s rights to perform vegetation maintenance work are unclear. Easements may 

be vague or incomplete. Past practices may have been ineffective and inconsistent in 

establishing a precedent for vegetation maintenance and tree removal on private property. 

These rights need to be established, re-established, and enforced on critical transmission lines. 

4. Organizational commitment to reliability-driven vegetation maintenance. 

Responsibility and authority for maintenance of vegetation in transmission corridors need to be 

clearly established and sufficient resources provided. The utility must adequately fund the 

program and enforce its standards and rights. This is particularly true for the most critical lines. 

Tree removal can be an unpopular maintenance activity with property owners, the public, and 

some governmental jurisdictions. Too often, necessary work is delayed or deferred by utility 

management because of customer and political pressures and local regulation. The decision to 

not complete necessary vegetation maintenance, either deliberately or by default, places the 

network and all customers at risk. Utilities need to demonstrate commitment to their 

responsibility for reliability and the greater public good. Regulators need to support these 

efforts. 

Mr. Goodfellow has 25 years experience in the electric utility industry; having 

held positions of responsibility for vegetation management, T&D operations, 

maintenance, and engineering at three large investor owned electric & gas 

utilities. John Goodfellow is recognized as a leading authority on utility vegetation 

management and reliability. He has conducted extensive research on treeinitiated electrical faults, and how they cause interruptions. He has direct 

experience with the practical application of Reliability Centered Maintenance 

(RCM) techniques in assessing electric transmission & distributions (T&D) 

systems including failure analysis & modeling and forensic engineering. 

John Goodfellow is currently on the Board of the Tree Research, Education, and 

Endowment (TREE) Fund, and is a past president of the Utility Arborist 

Association. He worked directly with the National Arbor Day Foundation in 

creating that organization’s “Tree Line USA” award program recognizing utilities 

for excellence in vegetation management. He has served on an industry 

standards committee, writing pruning standards for utility line clearance work. He 

also is a contributor to Dr. Alex Shigo’s pocket field guide “Pruning Trees Near 

Electric Utility Lines.” 

Mr. Goodfellow received a Bachelor of Science in Environmental Resources 

Management from SUNY College of Environmental Science & Forestry, and a 

Bachelor of Science in Forestry from Syracuse University. 
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MR. SIEGFRIED GUGGENMOOS, President, Ecological Solutions (Alberta, Canada) 

These recommendations are based on the premise that all trees with the potential to interfere 

with conductors are a liability. To reduce or prevent the likelihood of future tree and transmission 

line conflicts, utilities need: 1) to fully quantify the tree liability by systematic accounting, 2) to 

assess the impact of design and operating decisions on the value of the tree liability, 3) a 

responsive dedication of resources to manage the tree liability, and 4) authority to undertake 

work required to sustain or improve the safe, reliable operation of the system. 

1. The utility forest, which is comprised of all trees that have the potential now or in the future 

to interfere with the safe, reliable operation of the electric system, includes an enormous 

population of trees located outside the right of way. ‘Best in class’ utilities have assessments 

of tree work originating within the right of way and a cyclical program for the identification 

and removal of hazard trees located outside the right of way. The inadequacy in this 

approach is that it fails to comprehensively assess the risk of potential tree-conductor 

conflicts arising from healthy trees within the utility forest. As even healthy trees fail via 

lightening strikes and under wind or ice loading, all trees with the potential to interfere with 

conductors are a liability. While viewing trees as a liability puts utilities in conflict with 

community perceptions of trees as assets, the conflict does not change the fact that trees 

hold only the capacity to impair the safe, reliable operation of the electric system, not to 

augment it in any way. Recognizing and quantifying the utility forest as a liability provides a 

measure of the potential for, or risk of, tree-conductor conflicts. Furthermore, it connects and 

clarifies the influence of design and operating decisions on maintenance costs and reliability 

risks. 

2. A current barrier to reducing the likelihood of future tree and transmission line conflicts is 

easement terms. The clear width (distance between conductor and treed edge) set by the 

right of way width provided for under easement is based on protecting against treeconductor conflicts arising from conductor sway but fails to consider the extent of exposure 

to residual tree risk. This situation serves to illustrate the utility of the tree liability concept as 

it provides a measure of the consequence for the chosen right of way width. Narrower rights 

of way have lower capital costs but yield a higher tree liability. Accepting the greater tree 

liability involves both committing to higher annual maintenance costs and a higher risk of 

tree-conductor conflicts, a risk that is realized with each severe weather event. The use of 

tree liability accounting will also serve to highlight the need for very specific language in 

easements regarding vegetation management practices as the current written rights allow 

stakeholders to obstruct actions specifically designed to effectively manage the tree liability. 

3. On established transmission lines the key drivers increasing the tree liability are in-growth, 

tree growth and tree mortality. As these and other biological processes follow geometric 

progressions, there is a window of opportunity to monitor and respond to utility forest 

changes. Responsive dedication of resources limits the negative effects of the compounding 

tree liability and maintains the equilibrium around the selected acceptable tree risk. 

4. The primary use of a transmission line right of way should be the safe, reliable transmission 

of electricity. The use of tree liability accounting connects regulation to the maintenance 

costs and tree-related outage risks and brings clarity to the impact of regulation on the 

utilities’ ability to manage the tree liability. This will serve to guide regulators to authorize 

utility actions to reduce tree risks. 
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Mr. Guggenmoos (B.Sc.(Agr.), P.Ag., CPC ) has a degree in horticulture from 

the University of Guelph, Ontario, is a Professional Agrologist and Certified 

Professional Consultant. His career in vegetation management began in 1970. 

He has been involved in research on growth regulators and herbicides. Mr. 

Guggenmoos served as Executive Vice President and General Manager of Ace 

Vegetation Control Service Limited, a national Canadian vegetation management 

contractor serving oil and gas companies, pipelines, power companies, railroads, 

National Defence and municipal authorities. In 1985 Mr. Guggenmoos joined 

TransAlta Utilities, where he was a chief architect of the Distribution Line 

Clearance program which: reduced tree related outages 80%; saved 48 million 

dollars over two maintenance cycles; had a 98% customer satisfaction rating; 

showed a 21% increase in crew productivity. He was responsible for an 

extensive herbicide program, associated research and communication. In 

addition, he brought a financial focus to the program and was intimately involved 

in the design and assessment of contracting methods. In 1995 Mr. Guggenmoos 

formed Ecological Solutions Inc. (Ecosync) to provide consulting services in 

vegetation management and biotic greenhouse gas mitigation strategies 

including biomass derived energy. 

Mr. Guggenmoos has authored over thirty articles appearing in technical 

journals, magazines and industry newsletters. He has presented at numerous 

conferences including chapter and international levels of the International Society 

of Arboriculture, International Right of Way Association, Edison Electric Institute 

and regional Vegetation Management Associations. He has served as president 

and several terms on the board of the Industrial Vegetation Management 

Association of Alberta; has been a summariser for the Expert Committee on 

Weeds; is a member of the Alberta Institute of Agrologists, the International 

Society of Arboriculture, the Utility Arborist Association and the American 

Consultants League. 

MR. RICHARD JOHNSTONE, System Forester, Conectiv / IVM Industry Consultant 

(Delaware) 

The primary purpose of the utility corridors must be safe and reliable delivery of energy 

services. Vegetation growing within or near utility corridors must be compatible with this 

purpose. Other needs, such as landscape aesthetics, wildlife or endangered specie habitat, or 

other concerns can also be addressed, but they must be secondary in nature to prevent largescale power outages. Laws and ordinances should prevent the introduction of incompatible 

vegetation, and the rights and methods to perform necessary vegetation management work 

must be granted to the utilities and supported by the federal, state, tribal or local governments, 

so long as the work is performed under professional best management practices. 

One of the key difficulties for utility companies in accomplishing this task has been the 

acceptance and coordination of vegetation management with all applicable agencies and public 

groups. Safe and reliable electric service is a community responsibility and electric utilities 

cannot provide the needed level of quality service operating alone. Blackouts and natural 

disasters affect the safety and security of all our citizens, thus all governmental agencies, 

transportation and utility services should work in harmony for the greater public good. In order to 
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address this ubiquitous problem, all parties should support research into the establishment and 

subsequent management of compatible plants, and the removal and prevention of tree species 

found to be inherently hazardous to utility services. 

A utility-compatible plant nursery should be established at the National 

Arboretum in Washington, DC and in various climate zones throughout North America to 

research and provide appropriate planting stock for use in or near utility corridors. Likewise, 

research is necessary to establish the best management practices for unique areas of special 

concern within the various climate and plant regions throughout North America. To specifically 

deal with this issue, I created a non-profit organization whose objectives are applicable as 

general recommendations to the industry, as follows: 

• Develop, educate the public with respect to, and apply integrated vegetation management 

and conservation practices to provide safe, reliable, and accessible utility and highway 

rights-of-way that transport vital services for public necessity and homeland security; 

• Improve wildlife and endangered-species habitats, control exotic weeds, and lower risk of 

wildfire; 

• Inform and educate land managers and public officials so that best practices are used to 

resolve vegetation management problems in a safe, economical, and environmentally 

responsible manner; 

• Develop partnerships between industry and government so that best management practices 

are used to resolve vegetation problems in military installations, communities, forests, parks, 

and wildlife refuges; 

• With cooperation from land grant universities, industry, government, and conservation 

organizations, conduct research and disseminate information with respect to regional 

geophysiological differences in vegetation management practices. 

Mr. Johnstone has been in the utility vegetation management industry for 27 

years and is the System Forester for Conectiv Power Delivery serving 1.1 million 

customers in the states of Delaware, Maryland, Virginia and New Jersey. He is 

President of the non-profit corporation; Integrated Vegetation Management 

Partners, Inc. which specializes in researching and applying best vegetation 

management practices for industry, government agencies and conservation 

organizations. Mr. Johnstone also owns the consulting company; Vegetation 

Management with Environmental Stewardship, LLC that provides training and 

management plans in professional vegetation management. He directed the 

production of a training video by Virginia Tech Pesticide Programs titled; 

“Integrated Vegetation Management: Principles and Practices for Rights-of-Way”. 

He earned his BS degree in Forest Resources Management from West Virginia 

University in 1976. 

A Registered Professional Forester, he has served as President of the Utility 

Arborist Association and received their 2003 Education Award for adding to the 

knowledge and practices of utility arboriculture. He co-authored the 

“Environmental Stewardship Strategy for Electric Utility Rights-of-Way” for the 

Edison Electric Institute Vegetation Management Task Force, and is part of their 

negotiating team to develop memoranda of understanding between the electric 
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industry and federal agencies. He has served as an advisor for the Chesapeake 

Bay Program and presently advises Rutgers University Forestry Advisory 

Council. He conducts training for the U.S. Fish & Wildlife Service, the National 

Park Service, Department of Defense, Federal Highway Administration and 

Invasive Weed Councils and several universities. He also provides professional 

expertise for the production of a federal refuge manager vegetation management 

training video for the Department of Interior’s National Training Center. 

Mr. Johnstone has published three papers in the Journal of Arboriculture and in 

three International Symposia on Environmental Concerns and his work is 

referenced in several magazines and professional journals. Under his direction, 

Conectiv is a charter partner with EPA’s Pesticide Environmental Stewardship 

Program; they received the National Arbor Day Foundation “Tree Line USA 

Award” for the last 4 years; and earned the “2002 Project Habitat Award” for 

rights-of-way wildlife habitat improvements. 

MR. RANDALL H. MILLER, System Forester, PacifiCorp (Utah) 

I think North Americans have a deep attachment to trees, and consider it acceptable or even 

desirable to have tall-growing trees in transmission corridors. While, as a professional arborist, I 

share the public's fond sentiment for trees, acceptance of them in rights-of-way is misguided, 

and often results in emotional, political, governmental, media and legal opposition to tree 

removal associated with effective vegetation management. While persistent utilities can still 

complete their work, it's difficult and time consuming, regularly involving corporate legal, 

regulatory, communications, community relations and other staff in addition to utility arborists. 

While many utilities have long-standing educational "right tree in the right place" campaigns, I 

think these programs have been largely ineffective. I suspect one reason for this failure is a 

public misconception that transmission right-of-way work (and distribution work for that matter) 

is motivated by corporate greed or arrogance, rather than public interest. Consequently, I think 

neutral parties, such as regulatory agencies, should mount aggressive public education 

campaigns to augment existing utility programs. Currently, I think regulators provide only 

passive support for utility vegetation management activities, responding to complaints by 

explaining that utilities have the "right" to clear the lines, and then only after investigating that 

we can justify our plans. By moving to a proactive educational model, regulators can leverage 

their status as trusted public servants to help steer North American attitude in a more 

responsible direction. We must develop a collective attitude that considers it irresponsible to 

plant or cultivate tall-growing trees in transmission corridors, and not only accepts, but demands 

thorough, scientifically-based, utility vegetation management. 

Mr. Miller is Chair of the Edison Electric Institute's Vegetation Management Task 

Force. He holds a BS in Horticulture from the University of Wisconsin-Madison, 

and an MS in Urban Forestry from the University of Wisconsin – Stevens Point. 

He is an International Society of Arboriculture Certified Arborist and Certified 

Utility Specialist. He has served a six-year term on the International Society of 

Arboriculture's Certification Test Committee, is past President of the Oregon 

Urban and Community Forest Council, and currently serves on the Editorial 

Board of the Journal of Arboriculture. 
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He has a broad background in urban forestry and arboriculture, having worked 

since 1976 in the commercial, institutional and governmental sectors before 

becoming involved in utility arboriculture. He joined PacifiCorp in 1993, and has 

been System Forester with them since March 1999. He has over 35 

arboriculturally-related writing credits, including contributions to the Journal of 

Arboriculture, the Utility Arborist Association Quarterly, Arborist News, Tree Care 

Industry, the Journal of Forestry, and Golf Course Management. He speaks 

widely on arboricultural, urban forestry, and utility forestry related topics.

MR. MIKE NEAL, Arizona Public Service, President of the International Society of 

Arboriculture (Arizona) 

Potential Solution 

The reliability of power lines is critical to national security, public safety, and quality of life in this 

current electronic age. Unfortunately, there are many hurdles to overcome if we expect utilities 

to effectively manage vegetation near transmission (and distribution) power lines. Much of these 

hurdles occur as a result of varying constituencies and agendas that do in fact conflict. These 

conflicts result in the significant increase in the likelihood of similar outages as experienced on 

August 14th. 

Short-Term Line-Clearance Practice: Attempting to control the rapid growth of tall-growing tree 

species found growing in the vicinity of power lines through repeated pruning is clearly a loselose proposition. A tree that is genetically predisposed to grow to a natural height of sixty feet 

will always strive to be a sixty-foot tree regardless of how much and how often it is pruned. 

Over time, these repeated prunings frequently lead to unsightly, unnatural, and unhealthy trees. 

Long-Term Resolution: Key to a long-range utility vegetation management plan is getting the 

right types of trees into the right place. Implementation of the plan begins with the pruning back 

or removing all weak, dead, dying, or leaning trees along the sides of the right-of-way. Trees 

that must be removed also include all tall-growing tree species and fire-prone species located 

directly beneath a power line and those growing in such a position that the tree will require 

extensive and repeated pruning. 

In urban and residential areas, low-growing trees, that is, those species that naturally have short 

mature heights, can be grown safely beneath power lines. Over time, these trees will grow tallenough and wide enough to help obscure the power line and establish themselves as an 

attractive feature in the landscape. 

Transmission corridors should be provided with clearance distances such that no falling tree 

could possibly pass any closer than ten feet from an energized conductor. In many locations 

such a practice will clearly change the appearance of the landscape. This is not to say that the 

change will necessarily be for the worse, as that is a matter of perspective: 

• Developing the landscapes of rights-of-way into communities of low-growing plants including 

natural grasses, herbs, forbs, wild flowers and shrubs provides a sustainable supply of 

forage as well as escape and nesting cover for wildlife. A correctly managed utility corridor 

serves to link distant ecosystems together into a much larger and more biologically diverse 

natural area by serving as a passageway for wildlife movement. 
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• Open rights-of-way are not an eyesore. They provide attractive views into the forest, the 

colorful understory vegetation is aesthetically pleasing, and the corridors present 

tremendous wildlife viewing opportunities. 

• Wide corridors can serve also as an effective firebreak. The edge-effect provides an air gap 

in the forest that can stop, or at least slow the spread of a crown fire. As devastating forest 

fires in the western states have demonstrated, excessive fuel loads in the nation’s forested 

areas are a serious problem that cannot be corrected quickly. Wide, linear breaks in the 

forest can be a tremendous benefit in preventing the spread of a wildfire. 

My final recommendation is to encourage the development, adoption, and implementation of 

national vegetation maintenance standards that will apply to all electric installations. The 

standard should be based on universally accepted science, and developed with the active 

participation of all appropriate stakeholders. Once promulgated, all agencies, state, and local 

governments should accept these standards as the appropriate and required method for 

managing trees and vegetation near power lines. This effort will dramatically decrease the 

likelihood of future tree and power line conflicts. 

Mr. Neal, Arizona Public Service’s Systems Forester, graduated from West 

Virginia University with a degree in Forest Resource Management. Mike is an 

ISA Certified Arborist, an ISA Utility Specialist and a qualified party with the 

Arizona Structural Pest Control Commission. He is currently the President of the 

International Society of Arboriculture. The International Society of Arboriculture 

(ISA) has served the tree care industry for over seventy years as a scientific and 

educational organization. The ISA has 14,000 members in 20 countries. 

In addition, he serves on the Board for the Western Chapter ISA. Mike is a pastpresident of the Utility Arborist Association, an affiliate of the ISA. He serves as 

past-president of the Arizona Community Tree Council. 

His background includes 5-years experience in urban and classical forestry with 

the Florida Division of Forestry. He has been involved in utility arboriculture for 

the past 16 years. 

MR. JIM ORR, Asplundh Tree Expert Company (Pennsylvania) 

Trees are a natural variable controlled by the forces of nature. Vegetation is dynamic and can 

be controlled but never eliminated. Everyone involved must understand this basic premise. For 

more than 100 years, the electric utility industry has unsuccessfully searched for a quick fix to 

the complex problems that arise when trees and power lines compete to occupy the same 

space. Operating a reliable transmission grid depends on stable funding of the vegetation 

management program, experienced and informed managers, strong executive support, a 

commitment to research, and regulations and laws that balance the need for reliable electricity 

with the importance of trees to our society. 

Stable Funding

Consistent and adequate funding for vegetation management activities is critical for a reliable 

program. Stable budgets promote a consistent and dependable workforce. Interruptions in 

planned work due to budget cuts create windows of risk because vegetation does not stop 

growing when funding is postponed. Research has shown that the cost of delaying vegetation 
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management is significant. The Blackout showed that the increased risk to millions of 

customers is real. 

Informed Managers

A background in one of the natural sciences is important to the understanding of the dynamics 

of vegetation management on transmission corridors. Knowledgeable vegetation managers 

work with the natural forces of nature to encourage and develop vegetation on rights-of-way that 

is compatible with the need to transmit power. Such methods are both highly effective and cost 

efficient. Rights-of-way managers must stay current with developing new methods and 

techniques. 

 

Executive Support

Support from Executive management is vital to the success of a vegetation management 

program. From the budgeting process to protecting easement rights, management decisions 

have a great impact on system reliability. Fluctuating budgets may create high risk situations 

when scheduled work is postponed due to lack of funds. Equally critical are individual customer 

challenges to easement rights that allow unsafe vegetation conditions to develop at the expense 

of all customers. 

 

Support Vegetation Management Research

Funding of new and ongoing vegetation management research projects will result in the 

development of improved methods and practices for the huge variety of sites found across the 

grid. 

Regulatory balance

Perhaps the most difficult challenge is working with lawmakers and regulators to find a 

regulatory scheme that effectively balances the importance of reliable electricity with property 

rights and aesthetically pleasing landscapes. State and local regulations regarding allowable 

vegetation management practices often vary considerably. Since electric transmission lines 

cross international, state and local jurisdictions, the creation of a reasonably uniform set of rules 

and regulations should be an objective. 

Mr. Orr has served in the utility vegetation management industry for 34 years. 

He earned a BS in Forestry and Wildlife Management from West Virginia 

University and is a Registered Professional Forester and Certified Arborist. In 

1999, he was the recipient of the Utility Arborist Association (UAA) Lifetime 

Achievement Award and the Northeastern Weed Science Society named him 

Innovator of the Year in 1996. He has been the Editor, Executive Secretary and 

Secretary-Treasurer of the UAA. A past president of the West Virginia 

Vegetation Management Association, Mr. Orr also served on the West Virginia 

State Pesticide Advisory Board from 1975 to 1977. He has worked closely with 

Dr. W. R. Byrnes and the late Dr. W. C. Bramble on the Pennsylvania State 

Game Lands 33 Research Project for more than 25 years. Mr. Orr has made 

more than 65 presentations at major conferences across the US and Canada 

and published more than a dozen articles in various utility and arboricultural 

publications. 

Mr. Orr is currently the General Manager of Technical Services for the Asplundh 

Tree Expert Co. and is responsible for coordinating technical information on line 

clearance, trees and vegetation management for Asplundh field personnel and 

utility customers. Asplundh is the largest line clearance and vegetation 
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management company in the world with operations in the US, Canada, Australia 

and New Zealand. 

MR. DEREK VANNICE, Executive Director of the Utility Arborist Association (Illinois) 

The Importance of The Right Tree In The Right Place 

One of the key issues that have emerged as a result of the August 14th outage was a renewed 

focus on vegetation management and the importance of keeping trees out of power lines. 

Comments have been made putting the blame on utilities for not properly funding their 

vegetation management programs. This may or may not be the case. Even well funded utility 

vegetation management programs have tree-related outages. The simple fact is that trees and 

power lines do not mix. 

Trees are not like broken insulators or other hardware that can be fixed by replacement, trees 

are living organisms that when pruned will actually accelerate growth to make up for what was 

lost. Trees currently also have a much stronger meaning with the public than do poles and 

towers. To many people, trees are spiritual in nature and stir many emotions. When utilities 

work to obtain appropriate clearances, conflicts develop between the landowner and the utility. 

The utility is now placed in a no-win position. There is no short-term solution. However, there is 

something we can and should do. 

The federal government should assist in the development of a national effort that promotes 

planting the right tree in the right place. This should include comprehensive public educational 

efforts and possibly the promulgation of new laws that would prohibit the unnecessary planting 

of the wrong tree in the wrong place. 

This investment and commitment needs to be long term. If the regulators will work with the 

utilities to educate the public on appropriate tree placement based on species growth 

characteristics and proximity to conductors, the issues relating to improper line clearance will be 

minimized over time. In the urban environment, the life cycle of a tree is much shorter due to 

factors that include cyclical pruning by the utility. If the appropriate species is planted, pruning 

will not be necessary and the quality and condition of our urban forest will improve. 

This initiative does not only benefit utilities. The right tree in the right place benefits everyone. 

Cities will need to spend less money to maintain trees. Major storms will be less catastrophic in 

terms of initial damages as well as clean up costs. Even the insurance industry will benefit when 

the appropriate tree species are planted next to homes, streets and power lines. 

The key to long-term improvement in our communities and the urban forests which shade them 

is education about the right tree in the right place. The message has to get to every homeowner, 

city planner, landscape architect, utility, and government agency. Utilities, regulators and nonprofit associations must work together to make this happen. 

The Utility Arborist Association, a non-profit educational association, has always carried the 

right tree in the right place message and we will continue to do so in the future. However, we 

cannot do it alone. Educating the public on planting the right tree in the right place will have 

benefits that will last for generations. 
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Mr. Vannice is the Executive Director for the Utility Arborist Association and the 

Director of Certification for the International Society of Arboriculture. He started 

with ISA and UAA in 1992. In his positions at ISA and UAA, Vannice has had 

been involved in numerous new program start-ups where he served as the 

primary facilitator for team building, program development and implementation. 

Derek has also conducted numerous group and individual training exercises for 

employees and volunteers. Vannice serves as the primary spokesman for the 

utility arboriculture industry including expert testimony in regulatory hearings. 

Derek has given numerous presentations regarding utility pruning, liability, 

certification, licensure and customer service issues. Vannice also held various 

management positions in the utility industry before coming to ISA. Vannice holds 

a Bachelor of Science in Forest Management from Purdue University and a 

Masters Degree in Business Administration from Ball State University. 
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Appendix K: ANSI A300 PRUNING STANDARD (UTILITY PRUNING SECTION) 

ANSI A300 (Part 1)-2001 Pruning standard, sub-clause 5.9 is reprinted with permission of the 

Tree Care Industry Association (TCIA). Reproduction without authorized consent of TCIA is 

prohibited.

ANSI A300 (Part 1)-2001 Pruning sub-clause 5.9 is used in conjunction with the entire ANSI 

A300 Pruning standard. ANSI A300 standards are revised every five years on average. The 

next revision of ANSI A300 Pruning should be available by the end of 2006. Hard copies can be 

purchased by calling 1-800-733-2622 or visit 

www.treecareindustry.org/default.asp?main=content/laws/a-300.htm for more information. 

Full citation is provided as follows: ANSI A300 (Part 1)-2001 For Tree Care Operations, Tree, 

Shrub, and Other Woody Plant Maintenance - Standard Practices (Pruning).
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