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Emerald Ash Borer (EAB)
Damage Mitigation and
Management for Electric Utility
Reliability
Mike O’Connor – Consumers Energy
June 7, 2012
Purpose/Agenda
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• Purpose/Agenda
– Provide status of Emerald Ash Borer (EAB)
• Where is EAB
– Review risk/impact of damaged ash trees on electric utilities
• Tree Failure Mode
• Mortality/Failure timeframes
– Reliability Impacts
– Outline management/mitigation approach
• Legal / Regulatory Concerns
• Private Tree Service Approach
• Managed Risk Approach
– Communications
– Questions
2
EAB Infestation Status
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3
Tree Failure Mode
Typical ash tree failure mode is at ground level
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Tree Failure Mode
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Damaged Tree Impact on CE System
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• Outages from EAB-damaged trees increasing
– Highest system impact in south/southeast/east areas of state
– Expected to spread across the Lower Peninsula over the
next 5 years
• Tree related outages
– Annual outage impact expected to continue increasing over
the next 5-7 years, then abate
– Currently approximately 10,000 incidents per year occur on
the LVD system from all species of trees
– Approximately 15,000 average additional incidents per year
expected from dead ash trees – 150% increase in tree
related outages
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Ash Danger Trees
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Not to Scale
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DT Probability of Contact
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• Tree of given height has less
potential to contact line the
further it is growing from
centerline.
• Given a tree has equal chance
of falling any direction then
there is an approximate 17%
probability (on average) of a
DT hitting the line, however
• The closer the tree the greater
the probability.
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Survey Results and Impacts
7857
490
16.03
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Total ash danger trees sampled
Total miles sampled
Average number of ash danger trees per mile of LVD line
54,000
866,000
System miles of primary ROW
Total ash danger trees on LVD System
147,220
Ash Danger Tree Line Contacts Within 10 Years
9
Expected Customer Impacts
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• Reactive removal- repair damage after ash trees fall
•
•
•
•
•
•
3 trees/mile
$2460/mile (includes line crew and forestry crew cost)
$115M over 10+ years
$62M customer outage impact over 10+ years
$18M/year average total cost
Reliability impact- up to 1,000,000 additional customers
per year experiencing tree-caused outages
• Proactive removal- removal of all ash danger trees
outside of ROW on a planned basis
•
•
•
•
16 trees/mile
$1120/mile (forestry crew costs only)
$60M over 10 years
$6M/year
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Ash Tree Removal Approach
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• Proactive planned approach is beneficial to
customers
– Remove ash trees prior to causing damage/interruption
– Customers have more input on scope/schedule of work
– Written agreement with property owner on scope of
work/conditions
– Public and worker safety risk is reduced
– Focus in areas with significant ash tree mortality
• Drop tree, flush cut stump and leave wood/debris on
site
– Maintained areas- chip branches, wood left in manageable
lengths
– Unmaintained areas- windrow debris, large wood separated
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Proactive EAB Damage Mitigation
Levels
Level
Cost*
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Pros
Cons
1) Current ApproachRemove Ash Trees
within ROW on LVD
System
$0M
o Minimal impact on work
plan/productivity
o Does not address danger
trees outside of ROW
o High costs associated with
reactive response
2) Remove Ash Trees within
20 ft of ROW with
Property Owner
Permission
$34-38M
o Addresses approximately 60%
of ash danger tree reliability
risk
o Bucket access only
o Does not address all ash
danger trees or danger
trees of other species
3) Remove Ash Trees within
80 ft of ROW Centerline
(Property Owner
Permission)
$50-55M
o Eliminates ~90% of ash danger
tree reliability risk
o Significant cost
o Does not address all ash
danger trees
4) Remove Ash Trees within
80 ft of ROW Centerline
$60M
o Eliminates 99+% of ash danger
tree reliability risk
o Significant cost
o MDA involvement required
in declaring ash trees as a
nuisance
($3.4-3.8M/
year)
($5.0-5.5M/
Year)
($6.0M/year)
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Trial Circuit Data
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Ulmer Burt Circuit – 40 miles
Tree Units w/in 30 ft ROW - 2131
Ash DT 15-35 feet from line - 312
Percent additional trees
- 13%
Ash DT properties
Permission
No Response
Refusals
-
67
57
4
1
13
QUESTIONS
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