20230201Howell Exhibit 10 Schedule 1.pdf

DAVID J. MEYER VICE PRESIDENT AND CHIEF COUNSEL FOR
REGULATORY & GOVERNMENTAL AFFAIRS
AVISTA CORPORATION P.O. BOX 3727 1411 EAST MISSION AVENUE SPOKANE, WASHINGTON 99220-3727
TELEPHONE: [phone]
[e-mail]
BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION
IN THE MATTER OF THE APPLICATION )
OF AVISTA CORPORATION FOR THE ) AUTHORITY TO INCREASE ITS RATES ) AND CHARGES FOR ELECTRIC AND ) NATURAL GAS SERVICE TO ELECTRIC )
AND NATURAL GAS CUSTOMERS IN THE )
STATE OF IDAHO )
CASE NO. AVU-E-23-01
EXHIBIT NO. 10
DAVID R. HOWELL
)
FOR AVISTA CORPORATION
(ELECTRIC ONLY)
David James and Lisa La Bolle, January 23, 2023
2023 Avista Utilities
Wildfire Resiliency Plan
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 1 of 59
1 Avista 2023 Wildfire Resiliency Plan
January 23, 2023
January 23, 2023
January 23, 2023 David Howell
Statement from Avista Executive Management
2023 represents Avista’s 3rd full year of implementing the Wildfire Resiliency Plan. Avista’s wildfire
strategies are firmly rooted in our 135-year operating history and represent the collective knowledge of
Avista employees and fire agency professionals together with assistance from peer utilities, and most
importantly, engagement with customers. This Wildfire Plan, updated for 2023, builds upon strategies
developed in 2020 and aligns with the Company’s mission to provide safe, reliable, and affordable
energy. Avista’s Wildfire Plan is a 10-year program to reduce fire risk associated with the operation of
electric transmission and distribution facilities. It also reflects our commitment to partner with customers,
communities, and those who manage forest landscapes and fight fires.
We all have a role to play in minimizing the risk of wildfire.
Heather Rosentrater, Chief Operating Officer (COO)
______________________________________ Date: _________________________
Josh DiLuciano, Vice President Energy Delivery
______________________________________ Date: __________________________
David Howell, Director Electric Operations
______________________________________ Date: __________________________
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 2 of 59
2 Avista 2023 Wildfire Resiliency Plan
Table of Contents
Statement from Avista Executive Management .............................................................................. 1
Executive Summary .......................................................................................................................... 3
Avista’s Commitment to Wildfire Resiliency .................................................................................. 5
Why does Avista have a Wildfire Plan? ........................................................................................... 5
What are the Plan’s Goals? ............................................................................................................. 5
Why is Wildfire Risk Increasing? ...................................................................................................... 6
What is Avista’s Role? ..................................................................................................................... 6
What are the Risks? ......................................................................................................................... 7
Why is Avista Updating its Plan? ..................................................................................................... 8
Comparison of the 2020 and 2023 Wildfire Plans ........................................................................... 8
2020 Wildfire Plan Scorecard........................................................................................................... 8
2023 Wildfire Resiliency Program Elements ................................................................................. 11 Wildfire Risk Map ............................................................................................................................ 12
WUI at Avista ................................................................................................................................. 13
Community Outreach ..................................................................................................................... 14
Public Safety Power Shutoffs ........................................................................................................ 15
Equity .............................................................................................................................................. 16
2023 Wildfire Plan Performance and Goals .................................................................................. 18
Grid Hardening ............................................................................................................................... 18
Enhanced Vegetation Management ............................................................................................... 22
Situational Awareness: Automating the Dry Land Operating System ........................................... 26
Emergency Response and Operations .......................................................................................... 28
Wildfire Resiliency Actual & Estimated Costs ................................................................................ 29
2023 Wildfire Resiliency Plan Summary ....................................................................................... 30
2022 Fire Season Recap ................................................................................................................. 32
Impacts to Infrastructure ................................................................................................................ 33
2023 Fire Season Outlook ............................................................................................................. 34
Continuous Improvement (Lessons Learned) .............................................................................. 35
Challenges of Risk/Hazard Tree Program ..................................................................................... 35
Implementing Elevated Dry Land Mode (DLM) .............................................................................. 36
Transmission Steel Conversion ..................................................................................................... 37
Glossary of Terms .......................................................................................................................... 38
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 3 of 59
3 Avista 2023 Wildfire Resiliency Plan
Executive Summary

Avista published its first Wildfire Resiliency Plan in June of 2020. That plan introduced the risks, costs,
and benefits of implementing a holistic set of measures to reduce utility wildfire risk. The 2020 Plan built
upon Avista’s operating history responding to and mitigating for wildfire activity in addition to risk
mitigation strategies developed by California utilities in the aftermath of the 2017 and 2018 fire seasons.
This plan details the performance and investments made from 2020 through 2022 and serves to reaffirm
Avista’s commitment to reducing fire risk to communities, customers, and the company. Similar to other
utility wildfire plans, Avista is making investments in four key areas:

• Grid Hardening – to invest in electric line infrastructure to reduce spark-ignition outage events
and to protect critical assets from the impact of wildfires.

• Enhanced Vegetation Management – to inspect 100% of distribution line assets annually and
combine remote sensing technologies such as LiDAR and satellite imagery to aid in overall
vegetation management decision-making.

• Situational Awareness – to automate Avista’s non-reclosing protection strategy and align short
term, weather related fire risk with system protection levels.

• Emergency Response & Operation – to help customers be better prepared for wildfires and
partner with emergency first responders before, during, and after fire events.

Avista’s Wildfire Resiliency Plan spans 10 years from 2020 through 2029 and is
intended to accelerate existing infrastructure programs as well as conduct new
programs to reduce fire ignition risk from electric lines and to make systems more
resilient against the impact of fires. Avista’s Wildland Urban Interface (WUI) map
indicates that 2,746 miles (36% of system) of electric distribution lines are located in
high fire consequence areas. These zones reveal the intersection between forest land and human
development and are the focal point of Avista’s risk mitigation strategies.

Since 2020, Avista has completed upgrades on 392 miles of distribution lines (14%)
and has installed 287 steel transmission poles at a cost of nearly $50 million dollars.
Avista has made tremendous progress towards automating its distribution protection
system with upgrades to 120 of 224 devices (55%). These investments in
infrastructure will improve system resiliency and customer reliability by reducing the
number of fire ignition events. In 2022, Avista recorded 107 spark ignition events as
compared to the previous 5-year average of 117 indicating a reduction of 9%. While the vast majority of
spark-ignition events do not result in wildfires, it an important measure of fire risk performance. Similarly,
WUI
2,746
107
Spark
Ignitions
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 4 of 59
4 Avista 2023 Wildfire Resiliency Plan
Avista reported significantly fewer pole fires in 2022 versus the 5-year average with 50 events versus the
5-year average of 83 (40% reduction).1

Another key performance measure is how many times trees fall into
powerlines. Tree fall-in rates are closely linked with wind and weather
events but again, when vegetation comes into direct contact with electric
lines, there is potential for fire ignition. In 2022, Avista inspected 100%
of electric distribution lines to identify dead, dying, and diseased trees that
are most likely to fall into electric lines. Historically, Avista crews
inspected 20% of powerlines of a 5-year rotating cycle, but as part of the
Wildfire Plan have committed to full annual inspection to locate and
remove hazard trees. In 2022, over 22,000 trees were removed near powerlines that were weakened by
drought, disease, and insects. Insects such as the pine bark beetle and spruce moth have emerged as
significant contributors to tree mortality. In 2021, the Inland Northwest experienced profound drought
levels which have contributed to tree mortality. In 2022, 375 trees fell into electric lines which was slightly
higher than the 5-year average rate of 349. Reducing the number of tree falls is an important component
to Avista’s plan. Since 2020, Avista has invested over $27 million dollars to find and remove hazard trees
in addition to investments made in remote sensing technologies including LiDAR to assist with the
inspection process.

This plan, updated for 2023, will detail the progress to date and future projections associated with fifteen
projects ranging from grid hardening to risk-based vegetation management together with efforts to work
directly with customers to reduce fire risk at their homes and communities. Table 1 indicates the progress
from 2020 through 2022 and remaining work through 2029. Though many of the infrastructure programs
are expected to sunset in 2029, other programs such as vegetation management and fire risk monitoring
will continue well past 2029.

Programs and Resources 2020-2022 Progress 2023-2029 Remaining Percent Complete
Distribution Grid Hardening
Transmission Steel Poles
Fire Resistant Pole Wraps
Transmission LiDAR Survey
Distribution Satellite Imagery
Dry Land Automation
Capital Investment
O&M Investment

Key Performance Measure 2022
375 363 + 3% 59 80 - 26%
745 650 + 15%
50 83 - 40%
107 117 - 9%

1 Note that there were 154 poles fires in 2021 due to hot dry conditions followed by light rains, ideal conditions for pole fires. This compares to 92, 77, 68, and 65 poles fire per year in 2017 through 2020.
Table 1. Wildfire Progress and Work Remaining
1.
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 5 of 59
5 Avista 2023 Wildfire Resiliency Plan
Avista’s Commitment to Wildfire Resiliency
Why does Avista have a Wildfire Plan?
The most straightforward answer to that question is one word: Risk. The risk of wildfire is ever present in
the western United States. Though we have always faced the threat of wildfires, that threat is increasing
both as a function of population growth and as the result of a changing climate. As examples, on October
16, 1991, winds in excess of 70 miles per hour blew across the Columbia Basin and into the Inland
Northwest. The area was experiencing an extended drought and fire conditions were critical, resulting in
nearly 90 fires. On September 7, 2020, excessive winds hit the area again. 28 fires were reported in
Avista’s electric service territory, some as a result of vegetation contact with powerlines.

Avista developed a wildfire plan to help mitigate this risk. This includes modified infrastructure design and
operations such as Avista’s Dry Land operating program that limits automatic circuit reclosing in order to
reduce the risk of fire ignition. In the early 2000s, Avista migrated from wooden to fiberglass crossarms
on distribution poles, which has reduced the number of pole fires. And, in 2006, Avista began installing
steel rather than wood transmission poles to fire-harden the high voltage system. These types of tactics,
and a more comprehensive risk-based approach, became a focus in beginning in 2019 and will be
described in this report.

What are the Plan’s Goals?
Avista published its first Wildfire Plan in June of 2020 culminating 18 months of development working
with peer utilities, internal subject matter experts, and regional wildfire and emergency response
agencies. The initial 2020 Wildfire Plan identified 28 actions to reduce wildfire risk as grouped into four
categories: grid hardening, enhanced vegetation management, situational awareness, and emergency
response and operations. The stated goals of the 2020 Plan remain unchanged and include:

1. Emergency Preparedness – To recognize wildfire as a recurring threat to infrastructure,
communities, and utility customers.

2. Protect Life and Property – To protect physical assets, property, and human lives against the
threat of wildfires. To recognize fire potential as a manageable risk element of our operating and
maintenance strategies.

3. Financial – To mitigate the probability and consequence of direct financial costs and liability
associated with large scale fire events.

This Wildfire Plan is updated for 2023 and highlights the progress and milestones achieved since 2020.
While Avista started work in the second half of 2020, the combination of 2021 and 2022 serve as the test
bed for gathering direct feedback from employees, fire agency professionals, and customers. While many
of the elements of the 2020 Plan remain relevant, this updated report enjoys the benefit of hindsight and
provides focus for Avista’s approach to mitigating fire risk.

Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 6 of 59
6 Avista 2023 Wildfire Resiliency Plan
Why is Wildfire Risk Increasing?
Research indicates that climate change has
fueled the increase in wildfires across the
Western U.S. and that the frequency of
wildfires has quadrupled since the 1980s. Fire
season is also longer. Most areas report 80
additional days of fire season.2 Climate
scientists predict that a warming climate will
produce longer duration and more severe
droughts, especially in the Southwest United
States.3 In 2021, Eastern Washington and
Northern Idaho experienced severe drought
conditions with many locations receiving less
than half of normal precipitation from March
through August.4 As illustrated in Figure 2, the
U.S. Forest Service has extensive fire records
which indicate a tripling in fires larger than
1,000 acres, from an average of about 50 fires
in 1970 to nearly 150 today.5

What is Avista’s Role?
Electric faults occur when equipment fails or
when weather and wind cause branches or
trees to fall into powerlines. All electrical faults
involve a release of energy before the fault is
interrupted by the utility’s protective
equipment. The vast majority of electrical
faults do not result in fire ignition. In fact,
Washington’s Department of Natural
Resources (DNR) indicates that only 4 to 6% of wildfires involve electric lines.6 The California Public
Utility Commission (CPUC) recently reported that approximately 10% of the state’s wildfires involved
electric powerlines, but that 50% of the state’s deadliest fires involved utility ignition.7 When excessive
winds (e.g., 30-60 mph) combine with critical fire-weather (e.g., low relative humidity and drought), the
stage is set for large wildfires.

2 John T. Abatzoglou and A. Park Williams, “Impact of Anthropogenic Climate Change on Wildfire Across Western US Forests,” Proceedings of the National Academy of Sciences, October 10, 2016, https://www.pnas.org/doi/10.1073/pnas.1607171113 3 U.S. Environmental Protection Agency, “A Closer Look: Temperature and Drought in the Southwest,” https://www.epa.gov/climate-indicators/southwest
4 Nicholas K. Geranios, “2021 a Record-Breaking Drought Year in Parts of Washington,” HeraldNet, Sep. 20, 2021, https://www.heraldnet.com/northwest/2021-a-record-breaking-drought-year-in-parts-of-washington/ 5 Climate Central, “Graph: Hotter Years, More Fires in Western States,” https://www.climatesignals.org/resources/graph-hotter-
years-more-fires-western-states 6 DNR Wildfire Intel Dashboard, Statistics, https://experience.arcgis.com/experience/6cdda73cf6154949a1fae76ccb2900a0/page/Main-Page/?views=Statistics 7 California Public Utility Commission, “PSPS, History and Background,” www.cpuc.ca.gov/psps
Figure 2. USFS Fire Records as reported by Climate Central
Figure 3. 2020 Labor Day Fire Fighting
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 7 of 59
7 Avista 2023 Wildfire Resiliency Plan
What are the Risks?
As part of the Wildfire Resiliency
Plan, Avista tracks overhead
equipment failures, pole fires,8 and
spark-ignition events as key
performance indicators. We also
track the number of trees that fall or
grow into powerlines. Each of these
measures represents a situation that
may lead to a wildfire. Recent values
are summarized in Table 2.

These values represent a subset of unplanned outages that can be managed by upgrading powerlines
and removing trees, which are primary objectives of Avista’s Wildfire Plan. Project elements of the Wildfire
Plan are grouped into four categories:
• Grid Hardening – Upgrade infrastructure to reduce equipment failures and protect poles and equipment from the impact of wildfires.
• Enhanced Vegetation Management – Remove dead, dying, and diseased trees that could strike powerlines. Employ remote sensing such as LiDAR and satellite-derived information to aid in the inspection and identification process.
• Situational Awareness – Align utility system protection with fire-weather conditions.
• Emergency Response & Operations – Recognize wildfire as separate and distinct from other weather events and partner closely with emergency first responders and firefighters before, during, and after an event.
Though reducing spark-ignition events is a core tenant of Avista’s Plan, we acknowledge that fire risk
cannot be completely eliminated, and that actions and investments must balance against affordability,
reliability, safety and security, and other operating risks. Avista is committed to a multi-year Wildfire Plan
to reduce the number of fire ignition events. This updated plan describes that commitment.

8 Note that there were a high number of pole fires in 2021 due to that year’s hot, dry conditions followed by periods of light rain, ideal conditions for the electrical tracking between poles and wood crossarms that can lead to fire. Each year in the U.S. there are over 3,000 pole fires. Pole fires are caused by periods of very dry conditions followed by moisture, when leakage
current, which is normally present, heats and creates combustion in gaps where metal bolts connect wood crossarms to wood poles. This does not happen with fiberglass crossarms. For more information, see: John Lauletta, “The Industry’s Most Definitive Pole Fire Fact Sheet,” https://www.exacterinc.com/resources/uploaded/Brochures/Exacter%20Pole%20Fire%20Fact%20Sheet%20Final.pdf
Table 2. Distribution Outage Incidents
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 8 of 59
8 Avista 2023 Wildfire Resiliency Plan
Why is Avista Updating its Plan?
The 2020 Plan stated that Avista would periodically revise its strategies to incorporate lessons learned,
new information related to fire risk, and in response to feedback from customers, agency partners, and
regulators. Avista uses a Plan-Do-Check-Adjust framework to adapt business strategies, plans, and
processes to align with changing business and
physical climates. In fact, core elements of the
Wildfire Plan were derived from a series of
business process improvement workshops to
identify the opportunities to build upon Avista’s
operating history. Plan implementation is
governed by a steering committee whose
membership reflects a broad cross section of
Avista departments including Regulatory and
Rates, Financial Risk & Insurance, Electric
Operations, Community Relations, Corporate
Communications, Real Estate & Environmental,
Legal, and Asset Maintenance. In addition to
governance by the steering committee, an
executive management team routinely meets to
monitor progress and discuss forward looking strategies. Avista’s Board of Directors is provided quarterly
progress reports as well as two formal presentations annually. Wildfire is an enterprise level risk and
executive level oversight is essential for producing prudent and cost effective outcomes for customers.9
Figure 4 indicates the governance structure for Avista’s Wildfire Plan.
Comparison of the 2020 and 2023 Wildfire Plans
From June 2020 through December of 2022, Avista invested nearly $50 million dollars to upgrade
powerlines and equipment. This includes upgrades to 392 miles of electric distribution lines and the
installation of 287 transmission steel poles as part of the Wildfire program. It has also inspected over
10,000 miles of powerlines and removed nearly 42,000 dead, dying, and diseased trees, together with
other vegetation related tasks totaling $27 million. The 2020 Wildfire Plan included 28 recommendations
to mitigate wildfire risk. As we’ve initiated new projects and altered business processes, we’ve identified
elements that can be grouped together, those that remain as standalone programs, and those which
should be eliminated. The following section illustrates the current status of the original 2020 Plan
elements.

2020 Wildfire Plan Scorecard
The following table lists the recommendations included in the June 2020 Wildfire Plan including the
project status, key performance metrics (KPM), notes, and implications for the 2023 Wildfire Plan.

9 The Company continues to review the Washington Utilities and Transportation Commission Order 10/04, in Docket UE-220053, et. al., received on December 12, 2022, and will update with additional information as required by that Order, as appropriate, as we proceed through the 2023 wildfire season.
Figure 4. Avista Wildfire Governance
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 9 of 59
9 Avista 2023 Wildfire Resiliency Plan
2020 WF Plan Status KPM Notes 2023 WF Plan
1. Distribution Grid Hardening Active Single largest capital plan element. Standalone
2. DLM Circuit Reclosers Active 17 distribution line circuit reclosers reclosers to be installed through Grouped with DLM Automation
3. DLM Effectiveness Study Complete Published Dec. the Dry Land Mode operating
4. DLM Trigger Complete
Elevated and Extreme DLM modes added
Prescriptive trigger points to increase the system protection of distribution lines during periods of critical fire-weather conditions.

5. Transmission Steel Poles Active
287 wood poles converted to steel (Wildfire only)
Project areas align with 50-year fire history. Standalone
6. Transmission Wildfire-Related Inspection Active annually by Transmission
Visual inspection prior to fire season to identify fire risk situations. Standalone
7. Transmission Fire-Resistant Pole Wrap Active
1,000-1,500 wood poles wrapped annually
transitioning from fire-resistant paint to the Genics fire-resistant mesh wrap. Paint must be reapplied every 3-5 years. The
Standalone
8. Distribution Risk Tree Active Inspect 100% of electric distribution lines
satellite) is expected to reduce ground inspections, but those technology tools must be calibrated and verified before they can be fully utilized. Single largest O&M
Standalone
9. Public Safety: Right Tree, Right Place Active First year pilot project in 2022. Renamed Customer Choice: Safe Tree Program Standalone
10. Distribution Digital Satellite Imaging Active satellite scans in 2021 and 2022
Vendor – AiDASH. 100% of the system to be scanned each year. Standalone
11. Transmission Digital LiDAR Active 100% system LiDAR in 2022
resolution photographs in addition to LiDAR survey data to support infrastructure inspections.100% of the system is scanned each year.
Standalone
12. Conforming Transmission Rights-of-way Canceled fall-in incidents on transmission lines is very low versus cost of this
Active Standalone
14. Substation SCADA Active and 2 stations in 57 circuit breakers upgraded in 37 substations by 2029. Grouped with DLM Automation
15. DLM “Fire-Mode Ready” Devices Active reclosers circuit breakers. Software-only Grouped with DLM Automation
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 10 of 59
10 Avista 2023 Wildfire Resiliency Plan
2020 WF Plan Status KPM Notes 2023 WF Plan
16. Fire-Weather Dashboard Complete August 2020. Current version
Avista developed a fire weather monitoring tool leveraging ESRI GIS systems.
17. Emergency Operating System Not Started
Process design in 2023 meetings. A wildfire specific section will be added to Avista’s existing Standalone
18. Engineering Role in Major Events Complete Incorporated into transmission design workflow.
19. Wildfire Program Metrics Complete Monthly report
st Active Standalone
21. Expedited Fire Response Active place with Spokane County level incidents during fire season. Will add Idaho Dept. of Lands in Standalone
22. Fuse Coordination Complete
Complete
24. Fire Ignition Tracking Complete Data source: NIFC
25. Fire Suppression Water Additives Canceled that they are not adding chemicals to water cans. May revisit if use
26. WUI Layer in Avista GIS Complete
27. Wildfire Notification System Complete SMS Text messages sent from fire-weather dashboard.
28. Vegetation Management Included in Design Work Complete Integrated into workflow.
Table 3. 2020 Wildfire Plan Scorecard
Completed 2020 Wildfire Recommendations
Many of the 2020 Plan elements are noted as complete in Table 3. In some instances, the activity is
100% complete and there are no remaining tasks. However, many of the items noted as complete are
work processes and though they may lack direct mention in this 2023 Wildfire update, they are ongoing
and will evolve to support program objectives. Items of this nature marked as complete include: DLM
trigger (threshold), fire weather dashboard, wildfire program metrics, fuse coordination, circuit recloser
event reporting, WUI data layer in Avista’s Geographic Information System, and the wildfire notification
system. Two of the 2020 Wildfire recommendations were canceled, including: 1) the project to widen
transmission rights-of-ways and, 2) adding fire suppression chemicals to crew water cans.

Canceled: Transmission Rights-of-Way
In the 2020 Wildfire Plan, Avista planned to invest $50 million dollars over 10 years to widen transmission
rights-of-ways. In 2021, we analyzed the number of trees that have fallen into high voltage transmission
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 11 of 59
11 Avista 2023 Wildfire Resiliency Plan
lines. Since 2009 there have only been 58 tree related incidents that caused line outages on the 2,270
mile transmission system. Avista operates 700 miles of 230 kV transmission lines and another 1,570 of
115 kV lines. This equates to a very low annual rate of tree related outages, about 4 per year. These low
outage rates do not justify the expense of widening transmission rights-of-way. The Wildfire Team, in
collaboration with Avista’s Real Estate and Transmission Engineering Departments, agreed to terminate
the project. Avista’s Wildfire Steering Committee affirmed that decision.

Canceled: Chemical Additives
In 2022, the Wildfire Team consulted with several peer utilities to assess the benefits
of using chemical additives in fire suppression water cans. Avista’s line service trucks
are outfitted with water cans like the one shown in the Figure 5. They are also outfitted
with conventional fire extinguishers. The advantage of water cans is that they are
refillable. Chemicals can be added to water to inhibit evaporation and enhance fire
suppression. However, none of the peer utilities that we contacted including Idaho
Power, Puget Sound Energy, PacifiCorp, NorthWestern, San Diego Gas & Electric, or
Pacific Gas & Electric are using chemical additives in their water cans. Avista may
revisit this issue if it becomes an industry accepted best practice.
2023 Wildfire Resiliency Program Elements
Of the remaining programs elements marked as active, four of them stand out as major elements of the
Wildfire Plan based on their resource commitments:
• Distribution Grid Hardening
• Transmission Steel Pole Replacement
• Dry Land Mode Automation
• Distribution Enhanced Risk Tree Program
Those four elements account for most of the allocated resources from 2020 through 2029. The table
below summarizes these major projects and other risk mitigation measures.

Wildfire Category Project ID Project Scope (2020-2029)Resource (2020-2029)
Grid Hardening
$210.5M
10,000 poles $5.2M
Vegetation Management
Fuel Reduction $2.3M
Situational Awareness
DLM Circuit Reclosers $7.5M
DLM Fire Mode Ready Embedded cost
Figure 5. Crew
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 12 of 59
12 Avista 2023 Wildfire Resiliency Plan
Wildfire Category Project ID Project Scope (2020-2029)Resource (2020-2029)
DLM Substation $28.2M
Emergency Response & Operations
Embedded cost
Fire Safety Training Embedded cost
Planning & complete in 2020 Wildfire Avista’s Wildfire Team has 4 FTEs. $5.2M
Table 4 2023 Wildfire Plan Project Summary

A more detailed description of the active plan elements is included in the main body of this report.

Wildfire Risk Map
The concept of Wildland Urban
Interface is often used to describe
homes and properties most at risk
from wildfires.10 Human development
near the boundaries of forest lands is
among areas most at risk from
wildfires. Figure 6 illustrates the
various fire risk zones from forests to
suburban and urban areas. Though
fire risk is present in all of these
zones, rural and suburban zones are
generally at elevated risk due to the
abundance of natural fuels, proximity
to housing, and the lack of firefighting
resources.

In 2019, Avista developed a Wildland Urban Interface (WUI) map indicating the intersection between
electric infrastructure and burnable fuels as quantified by the U.S. Forest Service. This map provides
Avista with a means to quantify operating risks related to wildfire and helps the Company prioritize work
in these areas. Figure 7 illustrates the U.S. Forest Service Wildfire Hazard Potential map (WHP)11 which
categorizes burnable landscapes from very low to very high.

This map identifies the burnability of all landscapes. Though not evident in this illustration, the data set
quantifies fuel risk for every 270m x 270m square area. The data also identifies non-burnable spaces

10 Molly Mowery, “Living on the Edge: Get to Know Your WUI,” American Planning Association, January 16, 2018, https://www.planning.org/blog/blogpost/9141903/ 11 USDA Missoula Fire Sciences Laboratory, “Wildfire Hazard Potential,” https://www.firelab.org/project/wildfire-hazard-potential
Figure 6. Continuum of Wildland to Urban Densities
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 13 of 59
13 Avista 2023 Wildfire Resiliency Plan
such as water and city-
scape areas that lack
vegetation. It is interesting
to note that about 85% of
Washington fires are man-
made12 and that 50% of
Idaho fires fall into that
category.13 However, as
mentioned previously,
only 4-6% of all fires in
Washington State are
attributable to electric
utility operations.

WUI at Avista
Avista’s 2019 WUI map
combined data from the
Wildfire Hazard Potential
with the location of Avista
electric lines in areas of
low, medium, and high
population. This analysis
indicated that 3,240 miles
of Avista’s 7,725 mile distribution system were located in high fire threat districts (42% of the system).
Avista’s 2020 Wildfire Plan focused grid hardening and vegetation programs in these elevated risk areas.

For 2023, Avista’s WUI map was updated and now includes additional data which measures the impact
of fire on human development. The USDA’s Housing Unit Impact dataset14 combined with the Wildfire
Hazard Potential data mentioned previously, was used to refine the Avista WUI map. Areas shown on
the 2023 WUI map with either an orange or pink highlight indicate these high fire risk zones. Communities
like Chewelah and Colville border national forest lands, as do many other areas including Sandpoint, St.
Maries, Grangeville, and portions of the Lewiston/Clarkston Valley, placing them more at risk. In total,
2,746 miles of electric distribution lines are in high fire risk areas or about 36% of the system. This
analysis indicates slightly lower risk values as compared to 2019.

12 Washington Department of Natural Resources Investigations, https://www.dnr.wa.gov/Investigations#:~:text=Wildland%20Fire%20Cost%20Recovery%20and,in%20Washington%20are%20human%2Dcaused. 13 Idaho Department of Lands, “Managing Fires on Lands Protected by the State of Idaho,” https://www.idl.idaho.gov/fire/2016-
red-book-spreads.pdf 14 USDA/US Forest Service, “Wildfire Risk to Communities: Spatial Datasets of Wildfire Risk for Populated Areas in the United States,” 2020, https://www.fs.usda.gov/rmrs/datasets/wildfire-risk-communities-spatial-datasets-wildfire-risk-populated-areas-united-states
Figure 7. 2018 Wildfire Hazard Potential
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 14 of 59
14 Avista 2023 Wildfire Resiliency Plan
Avista’s WUI map is an important data set
because it charts the course for Wildfire
Resiliency and focuses efforts such as grid
hardening, enhanced vegetation management,
and the project to fully automate Avista’s Dry Land
protection system. One should note that the WUI
map does not predict where fires are likely to
occur. Avista’s WUI map indicates the potential
impact to human lives and property if a fire starts
near electric lines. A majority of the Palouse
region as well as the Big Bend area indicate low
fire risk, and this is largely based on sparse rural
populations. In contrast, areas around Spokane
and Coeur d’ Alene where suburban development
has encroached on forest lands, indicate higher
fire risk. Avista’s distribution grid hardening
program is aimed at reducing equipment failures
in these high fire impact zones.

An internal report is available that documents
Avista’s approach to developing the Wildland
Urban Interface map.
Community Outreach
Avista is committed to partnering with emergency
first responders, community leaders, and customers. The 2020 Wildfire Plan noted customer outreach
as a goal and described some of the initial meetings with fire departments, elected leaders, regulators,
and peer utilities. Avista’s communication outreach extends well beyond wildfire issues and has adopted
an ‘all-means and all-channels’ approach to communicating with customers and other interested persons.

In 2022, Avista established a cross-functional team including regional business managers, corporate
communication specialists, tribal relations
employees, customer engagement, electric
operations, and wildfire resiliency to improve
and expand Avista’s customer outreach related
to wildfire. The Company sponsored a series of
meetings with first responder groups and
county-level emergency management offices
which combine expertise from police, fire, and
emergency dispatch centers together with
ambulance services, volunteer support, and
elected officials. Avista attended meetings in 8
counties throughout Washington and Idaho in
order to provide information about Avista’s
Wildfire Plan and summer-time operating strategies. Avista also met with members of the Colville
Figure 8. Avista’s 2023 WUI Map
Figure 9. 2022 Community Outreach Activities
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 15 of 59
15 Avista 2023 Wildfire Resiliency Plan
Confederated, Spokane, and Nez Perce Tribes. Meetings were convened with the Washington
Department of Natural Resources, the U.S. Forest Service, the Bureau of Land Management, and the
Spokane City Council. A communications framework was developed to assist employees who routinely
meet with local emergency first responders.

Avista also conducted a series of residential customer telephone townhall meetings. Four meetings were
held with 36,000 customers invited to attend via telephone. In these meetings, Avista employees provided
an overview of the Wildfire Plan as well as information about changes to the protection system during fire
season and how that might impact them. At each meeting a fire agency expert was available to answer
questions about fire safety, home preparedness, evacuations, and other emergency response issues.
The focus of these meetings was to connect with customers who live in high fire threat areas. As noted,
36% of Avista distribution lines are located in these high risk zones. The convenience of attending by
telephone allowed customers to connect with utility employees and fire professionals more easily.
Questions ranged from “who do I contact about a tree near a powerline” to “how should I prepare for a
fire” to “how are evacuations handled in my area.” The response from customers was very positive.
Customers gave Avista an approval value rating of 83%.

Conducting telephone townhall meetings require significant planning, coordination, and internal support,
but the benefits both to customers and the Company was tremendous. Avista’s nearly 1,800 employees
work and live in many of the communities where fire risk is high. It is important that we partner closely
with emergency professionals, community leaders, as well as customers to understand fire risk and to
work together before, during, and after a wildfire event. Providing clear and concise communication
together with receiving feedback are important components of implementing a successful wildfire
mitigation plan.

In 2023, Avista will build upon the experience in 2022. We plan to include more counties in the information
sharing sessions and connect with additional fire departments, first responders, and forest managers.
We also plan to expand the scope and scale of the customer telephone townhall meetings and provide
messages in multiple languages.
Public Safety Power Shutoffs
Public Safety Power Shutoffs (PSPS) were first used by San Diego Gas & Electric (SDGE) following the
2007 “Witch Fire” which caused extensive damage to homes and infrastructure. SDGE began an
intensive program to reduce fire risk, including the plan to pre-emptively shut off power during periods of
critical fire weather. Following the 2018 fire in Paradise, California, Pacific Gas & Electric (PG&E) and
other California utilities developed their own PSPS plans. During the six year period from 2017 to 2022,
PSPS was initiated 90 times in California as shown in Table 5.

The use of PSPS in California peaked in 2019 and 2020 but is now used less frequently, primarily in
response to feedback from customers and regulators. At present, many utilities now describe their use
of PSPS as a “measure of last resort” for use only after other mitigation strategies have been exhausted.
For example, in Idaho Power’s Wildfire Plan they describe the use of PSPS as limited to “where wildfire
risk is high due to extreme weather conditions” and “as a last resort to prevent wildfires.” On Puget Sound
Energy’s website, they describe PSPS as: “During high-risk weather conditions, PSE may need to
proactively turn off power lines to help prevent wildfires.” When PacifiCorp developed their PSPS plan
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 16 of 59
16 Avista 2023 Wildfire Resiliency Plan
as required in California, they announced that they would extend the practice to other operating regions
including Washington, Oregon, and Idaho. While the use of PSPS has become controversial, with some
claiming that it creates more harm than it mitigates, PSPS will continue to play a role in reducing utility
fire risk.
In 2021 and 2022, Avista reviewed various utility PSPS strategies in order to understand the risks, costs,
and benefits of PSPS. Avista is currently studying the development of criteria for potential implementation
of public safety power shutoffs. Avista has studied implementing
PSPS over the past couple of years, including analyzing the
potential costs to Avista customers based on California’s PSPS
programs. These estimates range from $21 to $57 million per year
for a similar type of PSPS plan if implemented in Avista’s service
territory. This year we are taking an in-depth look at what other
utilities, especially our Northwest neighbors, are currently doing, as
many utilities have changed their practices since we began to look
at this. Avista will be examining the analytics around what could
potentially trigger a PSPS event in our service territory, the impacts
on our customers (especially those who are most vulnerable) and
how we might move forward with a PSPS plan that is suitable for our
own service territory and our customers’ needs. A team is coming together to study this issue in detail,
and we hope to have recommendations in place by the end of 2023.
Equity
Utilities, along with other large businesses, are increasingly being challenged to ensure equity (fair
treatment) for all customers, especially vulnerable customers. In Avista’s Washington service territory,
61 of 133 census tracts indicate populations that are designated as Highly Impacted Communities or
Vulnerable Populations as defined by the Washington State Department of Health.15 More than 65% of
Avista’s high fire threat districts coincide with 2010 census tracts that are “overburdened and

15 Washington State Department of Health, “Instructions for Utilities to Identify Highly Impacted Communities,” https://doh.wa.gov/data-statistical-reports/washington-tracking-network-wtn/climate-projections/clean-energy-transformation-act/ceta-utility-instructions
Figure 10. Business Sign in California during a PSPS Event
Table 5. PSPS Events in California
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 17 of 59
17 Avista 2023 Wildfire Resiliency Plan
underserved” according to the Council on Environmental Quality’s (CEQ) Climate and Economic Justice
Screening Tool.16 This includes tribal areas served by Avista.

In Washington State, 1,044 of 1,708 miles of powerlines located in high fire risk zones are in underserved
and financially overburdened communities. In Idaho, 794 of 1,037 distribution line miles are located in
underserved areas and high fire risk zones. Avista’s WUI map indicates that 1,838 powerline miles are
located in underserved communities out of the total mileage of 2,746 (67%). By definition, Avista’s most
capital intensive program, electric distribution grid hardening, will have significant impact on these
communities. Avista recently applied for a federal grant to assist with its grid hardening program.17 If
Avista is successful in receiving these federal grant dollars, we have committed to converting 175 miles
of existing overhead lines to underground facilities. Underground facilities incur electric faults at a rate 50
times less than overhead systems. This work would not only reduce fire risk in some of the most
vulnerable communities, but also significantly improve reliability for these customers.

As part of Avista’s state-required Clean Energy Implementation
Plan (CEIP),18 the Company is committed to ensuring that
disadvantaged communities benefit from investments in clean
energy. Avista has a long history of providing energy assistance
and delivering energy efficiency programs to disadvantaged
communities. For decades, Project Share has helped thousands of
customers heat and light their homes. Partnerships with SNAP,
various food banks, and emergency assistance from the American
Red Cross have allowed Avista to help people who are struggling
to meet basic life needs. Avista’s website (www.myavista.com)
provides information about how to arrange for payment assistance
and lists other community resources. Avista’s customer contact center includes a specialized team called
CARES (Customer Assistance Referral and Evaluation Services) that supports and assists vulnerable
customers and acts as a liaison between the customer and community partners. They are specially
trained to help people who need assistance with their energy bills or with other resources such as food,
housing, and medical care. Though Avista relies on community partners such as the Second Harvest
Food Bank, Vanessa Behan Crisis Nursery, Red Cross, and many others, we are a trusted advisor for
many customers and are committed to improving people’s lives.

The Wildfire Plan is no different from many other Avista initiatives. Those most at risk from wildfires are
typically also the most disadvantaged and economically challenged communities. These communities
are often located in rural areas where electric service is threatened by terrain, weather, and human
factors. By focusing on areas of highest risk, the bulk of the resources allocated to the Wildfire Plan will
flow to these disadvantaged communities.

16 Climate and Economic Justice Screening Tool, https://screeningtool.geoplatform.gov/en/#3/33.47/-97.5 17 2022 Grid Resilience and Innovation Partnership Program Grant, https://www.energy.gov/gdo/grid-resilience-and-innovation-partnerships-grip-program
18 The Clean Energy Transformation Act (CETA; the Laws of 2019, Chapter 288) requires Washington’s electric utilities to file a Clean Energy Implementation Plan (CEIP) every four years. https://www.utc.wa.gov/regulated-industries/utilities/energy/conservation-and-renewable-energy-overview/clean-energy-transformation-act/clean-energy-implementation-plans-ceips
Figure 11. MyAvista.com Website
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 18 of 59
18 Avista 2023 Wildfire Resiliency Plan
2023 Wildfire Plan Performance and Goals
Grid Hardening
The goals of grid hardening are to reduce the number of spark-ignition
events on the distribution system and to protect critical infrastructure from
the impacts of fire. Avista supports four projects within grid hardening:19

• Distribution Grid Hardening
• Transmission Steel Pole Conversion
• Fire Resistant Wraps on Wood Transmission Poles
• Annual Fire Inspections on Transmission Lines

Distribution Grid Hardening
The single largest program in the Wildfire Plan is Distribution Grid Hardening. This effort targets portions
of electric circuits located in high fire threat areas with the goal of reducing spark ignition events. Though
Avista has asset maintenance programs to replace poles and equipment, existing programs are
condition-based and support reliability objectives. Wildfire Distribution Grid Hardening focuses on
upgrades most likely to reduce spark ignition events and poles fires. The scope of this work includes:
• Replace wooden crossarms with fiberglass to mitigate pole fires.
• Replace small copper wire with modern steel-reinforced wire to
reduce conductor failures.
• Install wedge-bail clamps at hot tap connector locations to prevent
thermal failures.
• Add or replace wildlife guards to mitigate electrical contacts.
• Replace wood with metal poles at critical span locations such as
highway and river crossings.
On average, Avista experiences about 80-90 pole fires per year mostly
related to wood crossarms. By replacing wood crossarms with fiberglass
units, leakage current is substantially reduced, and pole fire risk is much
lower. Much of the small copper wire such as #6 and #8 was installed prior
to 1950, with some wire sections dating back to the early 1900s. These old
and obsolete wire types fail at higher rates than do modern aluminum
conductors. Animals cause about 8% of Avista’s outages but animal guards
at transformers and other connection points are an effective means of
reducing electrical contacts. Though hot taps fail at a low rate, a majority of
peer utilities use a bail type connector in conjunction with hot taps to
prevent burn downs, thus Avista crews are adding these connectors. At critical spans such as highways
or river crossings, line personnel are replacing wood poles with metal units to strengthen those spans.

19 The Company continues to review the Washington Utilities and Transportation Commission Order 10/04, in Docket UE-220053, et. al., received on December 12, 2022, and will update with additional information as required by that Order, as appropriate, as we proceed through the 2023 wildfire season.
Figure 12. Pole fire associated with wood crossarm
Figure 13. Grid Hardening Work
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 19 of 59
19 Avista 2023 Wildfire Resiliency Plan
As noted, the goal of
distribution grid
hardening is to reduce
incidents mostly likely to
produce spark ignition.
Avista tracks outage
performance on a
monthly basis including equipment failures, poles fires, and spark-ignition events. Table 6 indicates
annual measured values as compared to the 5-year average (2018-2022).20

Converting overhead line sections
to underground cables is not listed
as a component of distribution grid
hardening. Avista has conducted
underground conversion of
overhead lines on a case-by-case
basis, but in most existing situations
the physical challenges create an
undue economic burden,21 making
conversion infeasible. To date,
Avista has converted less than 2% of lines to underground cable under
the Grid Hardening Program. However, for new applications, such as a
new subdivision or business development, costs can be more
manageable. In fact, over the last five year period, Avista crews have
installed over 500 miles of underground cable and have removed over
100 miles of overhead lines. Avista has also made a commitment that
new distribution facilities located in high fire risk zones will be installed
underground to mitigate future risk.

In 2022 Avista completed upgrades on 180 miles of distribution lines.
Some of this work took place on Tribal lands, which requires careful
coordination with cultural resources.
Annual grid hardening results are shown in Table 7. Avista plans to
perform grid hardening on 2,746 miles of distribution lines, but at present
resource levels, this project plan will produce a net deficit of 693 miles at

20 Note that there were a high number of pole fires in 2021 due to that year’s hot, dry conditions followed by periods of light rain, ideal conditions for the electrical tracking between poles and wood crossarms that can lead to fire as described in the footnote on page 6. 21 Underground cables are twice as expensive (or more) than overhead lines, in part due to restoration costs (sidewalks,
roadways, landscaping) and environmental impacts. Maintenances costs are also significantly higher due to limited access. For more information: David Baker, “Despite Being Safer, Underground Power Lines Are Very Expensive,” San Francisco Chronicle, October 23, 2017, https://www.govtech.com/fs/infrastructure/despite-being-safer-underground-power-lines-are-very-xpensive.html
Table 6. Distribution Outage Rates
Table 8. 2020-2029
Distribution Grid Hardening
Table 7 Distribution Grid Hardening Details
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 20 of 59
20 Avista 2023 Wildfire Resiliency Plan
the end of 2029. As noted, Avista recently applied for federal grant assistance in which Avista committed
to undergrounding 175 of those 693 miles and complete all upgrades by the end of 2029.

Transmission Steel Pole Conversion
Transmission lines are particularly vulnerable to wildland fires. Currently about 37% of Avista’s
transmission poles are steel, which protect these critical assets from wildfires. In 2006, Avista adopted
steel poles as standard construction and since then, several lines have been upgraded, including portions
of the Benton-Othello, Chelan-Stratford, and Coeur d’Alene-Pinecreek transmission lines. In 2021, Avista
conducted analysis using 50 years of fire history to determine which transmission lines were experiencing
recurring impacts from wildfires. This analysis indicated that several transmission lines are particularly
vulnerable to recurring wildfires. Lines
most at risk from fire, such as the Addy-
Gifford line, are slated for wood to steel
conversion. Other wood pole lines, in low
vegetation areas, are being protected with
a fire-resistant wrap product.

In 2021 and 2022, transmission upgrades
were focused on the 21-mile Addy-Gifford
115 kV line. This transmission line serves
areas near the Columbia River including
the towns of Wellpinit and Inchelium,
Washington, both of which are Named
Communities. Most transmission lines are
part of a networked grid, and redundancy
helps isolate customer impact during outages. However, some lines, like Addy-Gifford, operate in a radial
one-way fashion. This makes the work very challenging since the line must remain energized during
construction. In 2023, wood-to-steel conversion is slated for transmission lines near the Devil’s Gap
Substation which connects the hydroelectric dams of the lower Spokane River (Nine Mile, Long Lake,
and Little Falls) with areas west of Spokane and communities including Reardan, Davenport, Odessa,
and Othello.

Table 9 indicates the number
of steel poles that were
installed as part of the Wildfire
Plan in addition to traditional
condition-based replacement
and construction of new
facilities. The table also
includes the number of wood
poles that were protected using a fire resistant (FR) mesh wrap product. The Wildfire Plan has budgeted
for approximately 1,000 steel pole replacements on the transmission system through 2029, with
approximately 6,000 wood transmission poles receiving fire mesh wrap.
Figure 14. Wildfire near Beacon Hill, Spokane WA
transmission lines near
Spokane. Steel (on the
left) was undamaged;
wood (on the right) was
destroyed.
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 21 of 59
21 Avista 2023 Wildfire Resiliency Plan
Fire Resistant Wraps on Wood Transmission Poles
Avista began using fire-resistant paint to protect transmission poles as early as 2005. Though the paint
has proven effective in protecting poles from fires, it has a limited expected life and requires maintenance
every 3 to 5 years. Avista worked with
Southern California Edison to adopt a
more resilient product for protecting
transmission poles at-risk from
grassland fires. Fire resistant mesh wrap
incorporates a heat activated chemical
on a steel mesh substrate. When
activated, the chemical expands to seal
the pole and protect it from fire. This
product works well in protecting wood
poles that reside in grassland areas
where fires move quickly and are low to
the ground. Protecting wood poles from
the impacts of wildfire also supports
reliable operations for customers.

Avista expects to wrap approximately 1,000 wood transmission poles per year. Crews wrapped 1,454
poles in 2022 and plan to continue work in the Company’s West Region, which contains the Davenport
and Othello operating districts. Several 115 kV transmission lines are located in this area. These lines
are subject to recurring grassland fires such as the Lind and Wagner Road fires that occurred in 2022
(see Addendum for 2022 fire season details).

Annual Fire Inspections on Transmission Lines
Avista conducts annual inspections of transmission lines prior to the summer operating season.
Generally, inspections are conducted via helicopter, vehicle, or on foot, with maintenance personnel
looking for failed equipment, bird nests, broken insulators, and other structural defects. The Wildfire Plan
extends that activity to identify conditions that might lead to fire ignition. Table 10 indicates the costs for
all grid hardening programs including transmission inspections. Note that “Transmission
Inspection/Construction” is listed both in the Capital and O&M portions of the table. Inspection is an
expense activity (O&M) while the follow-up capital maintenance is an investment in plant.

Maintenance personnel are also using the high resolution photographs taken during LiDAR (Light
Detection and Ranging) survey flights to help identify both vegetation and infrastructure issues. These
photos aid in the inspection process and are an added benefit when conducting vegetation inspections.
LiDAR is an industry best practice for mapping transmission lines and their proximity to vegetation. It is
explained in more detail in the Enhanced Vegetation Management section of this report.

Grid Hardening Financials
Distribution grid hardening represents the single largest capital investment in the Wildfire Plan,
comprising about 87% of total capital expenditures and about 60% of total program expenditures over
the ten-year period (2020-2029). Grid Hardening expenditures are shown in Table 10.
Figure 15. Fire resistant mesh wrap demonstration
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 22 of 59
22 Avista 2023 Wildfire Resiliency Plan

Table 10. Grid Hardening Program Costs. 2020-2022 Actual. 2023-2029 Projected.

Enhanced Vegetation Management
Vegetation management is an integral part of maintaining
overhead electric distribution and transmission lines as well as
reducing fire risk. Historically, utilities have trimmed and removed
trees with a focus on service reliability and grid security. Avista
has a long history of deploying industry best practices, including
the use of tree growth inhibitors and herbicides to retard shrub
growth, together with cycle-based tree trimming and hazard tree
removals. For transmission lines, Avista manually inspects all
230 kV and WECC Path 115 kV lines (~ 850 miles) each year as
required by federal regulators. Remaining 115 kV lines are
manually inspected on a 3-year cycle.

As part of the Wildfire Program, distribution cycle trimming has
been decoupled from hazard tree inspection, and in 2022 Avista
inspected 6,466 miles of distribution lines, which is 100% of the
system located outside of metro urban areas. Also in 2022, crews
removed nearly 19,000 dead dying and diseased trees that could
strike electric lines. The commitment to 100% inspection of
distribution lines is a significant lift for Avista’s vegetation
planners and field crews.

Tree contacts with powerlines are categorized as either grow-in risk (encroachment into lines) or fall-in
risk. Dead, dying, and diseased trees are more likely to fall into electric lines than live green trees. Trees
fall into electric distribution lines five times more often than they grow into them. A key performance
measure of the Wildfire Plan is to reduce the number of tree incidents. Table 11 indicates the tree incident
rates for both distribution and transmission lines. The 5-year average is measured from 2018-2022.

Figure 16. Dead tree falls into powerline
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 23 of 59
23 Avista 2023 Wildfire Resiliency Plan
As evident in Table 11, trees
incidents on the distribution
system far exceed
transmission levels. In most
situations, transmission lines
occupy dedicated corridor
rights-of-way which afford the
utility greater authority to
manage vegetation. Also,
transmission systems are
regulated by federal agencies such as FERC and NERC with prescriptive mandates for vegetation. A
premium is placed on the reliability and security of the nation’s high voltage transmission grid, and that
focus is reflected in overall reliability performance, including tree incidents. Avista’s Wildfire Plan did not
alter the vegetation maintenance practices on the transmission system but did add LiDAR surveys to aid
with inspections.

Enhanced vegetation management under the Wildfire Plan represents new activities such as digital data
collection (LiDAR and satellite) as well as incremental activities beyond what was historically undertaken
by Avista vegetation managers. These activities include:
• 100% Distribution Risk Tree Inspections
• Transmission LiDAR
• Distribution Satellite Imaging
• Customer Choice Safe Tree Program
• Fuel Reduction Partnerships

100% Distribution Risk Tree
As noted, Avista increased the annual
inspection of the electric distribution system
from 20% to 100% of non-urban areas as part
of the 2020 Wildfire Plan. The Company
began ramping up activities starting in 2020
and achieved 100% inspection in 2022. Table
12 indicates the program results by year. Note
that tracking inspections and remediations
performed on time started in 2022 and that no
goals are set for how many trees will be
removed or trimmed or for corridor clearing requirements, as this varies greatly from year to year and is
dependent upon many factors outside of the Company’s control such as drought conditions and insect
infestations.

Avista is committed to removing risk/hazard trees within six months of identification. The Company
continues to work with line clearance contractors to build a local workforce to support that goal.
Table 11. Tree Incident Rates
Table 12. Enhanced Vegetation Management Program

Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 24 of 59
24 Avista 2023 Wildfire Resiliency Plan
Transmission LiDAR
Since 2000, Avista has used LiDAR surveys to assess vegetation
encroachment and fall-in risks on the transmission system. Digital
data supplements visual inspections and helps vegetation planners
prioritize and prescribe treatments including herbicide applications,
tree trimming, and tree removal. Transmission vegetation activities
are regulated by federal agencies, and tree contacts are infrequent
as indicated in Table 11. Historically, transmission lines were trimmed
on a calendar cycle, but LiDAR is changing that practice. Digital data
combined with machine learning computer algorithms allow
vegetation planners to use a risk-based approach to treatments
rather than maintenance cycles. While Avista is still calibrating LiDAR
information based on human observations, digital inspections are
quickly becoming the industry standard practice and allow for a
complete vegetation record, including the efficacy of field work along
with the information necessary to create future work plans.

Distribution Satellite Imaging
Similar to the LiDAR project for transmission, Avista is incorporating satellite digital data to aid vegetation
planners with the inspection and planning process. Satellite systems are quickly evolving and apply
machine learning computer algorithms to large data sets and help vegetation planners create risk-based
work plans rather than relying solely on cycle trimming. For many years, Avista has used cycle trimming
to maintain vegetation near distribution lines on a rotating 5-year cycle. However, some areas have higher
growth rates and may require shorter trim cycles, while other areas with slow-growing trees may
accommodate longer cycle times. Beginning in 2020, Avista partnered with AiDASH to provide satellite
data along with their Intelligent Vegetation Management System (IVMS).22 Like the LiDAR project,
vegetation planners are working with
AiDASH to calibrate the system and
align computer-derived assessment with
field observations. In 2023, Avista
vegetation planners intend to transition
their work plans to the IVMS system.
This will allow them to customize the
cycle trim times and incorporate a risk-
based approach to work planning. In
short, they will focus attention in areas
with higher levels of tree encroachment
risk and outage rates as well as
increased fire risk rather than solely
relying on cycle trimming.

22 AiDASH Intelligent Vegetation Management System https://www.aidash.com/vegetation-management-system/
Figure 17. Avista transmission corridor
Figure 18. LiDAR Image of Transmission Line
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 25 of 59
25 Avista 2023 Wildfire Resiliency Plan
Customer Choice – Safe Tree Program
In 2022, Avista initiated the Safe Tree Program
modeled after the “right tree, right place”
philosophy of replacing tall growing trees near
powerlines with shorter species. This concept has
been in practice for decades and Avista has
incorporated this concept into vegetation
planning. However, from a wildfire risk
perspective, the Company is expanding this
concept and is working more directly with
homeowners to remove tall trees and replace
them with powerline-friendly species. Avista
recently conducted a pilot project and contacted
over 600 homeowners near Kellogg, Idaho.
Homeowners were connected with local tree
arborists to remove tall trees.
Table 13 indicates the
program’s performance in
2022. Customers responded
favorably to this program and it
will be expanded to additional
areas of the service territory.

Fuel Reduction Partnerships
Also in 2022, Avista partnered with the Washington Department of Natural Resources and the Idaho
Department of Lands on their fuel reduction projects. Both Washington and Idaho have established
programs which include tree thinning and brush removal along with prescribed burns. Avista is helping
close some of their funding gaps and are targeting areas with electric lines. This a modest program and
while we realize that we cannot significantly change the fuel regimes on a landscape level, these
programs do reduce risk for homeowners. By partnering with agency professionals, fuel reduction can
reduce the risk of wildfire to homes and communities by leveraging existing programs.

Enhanced Vegetation Management Financials
Table 14 indicates actual and projected costs for enhanced vegetation management from 2020 through
2029. Note that the distribution risk tree program accounts for 83% of the overall Wildfire Plan operating
and maintenance activities. Note also that costs for the risk tree program peak in 2022 and 2023 as field
crews work through the initial backlog of hazard trees.

Figure 19. Example of Fuel Reduction
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 26 of 59
26 Avista 2023 Wildfire Resiliency Plan

Situational Awareness: Automating the Dry Land Operating System
Avista has developed a computer algorithm to monitor, forecast, and
adapt to fire-weather events. Avista’s Fire Weather Dashboard
combines the National Weather Service’s 7-day forecast with Avista
infrastructure data to quantify the daily fire risk on 350 distribution
circuits. This allows system operators to align circuit protection settings
with fire-weather conditions and to minimize the potential for spark-
ignition on a circuit-by-circuit basis. This monitoring system is similar to
those used in California. In fact, Avista worked closely with San Diego
Gas & Electric to calibrate the system to achieve a balance between
electric service reliability and fire ignition potential. This monitoring
system supports Avista’s fire season circuit protection program known
internally as Dry Land Mode.

Avista developed
the Dry Land Mode
(DLM) operating
program in the
early 2000s in
response to a number of very active fire years in the
late 1990s. Historically, circuit reclosers are
programmed to automatically reclose several times
after detecting a line fault in order to maximize service
reliability. However, analysis indicated that in some
situations, this series of reclose attempts was adding
to fire ignition potential. Engineers developed the
DLM program to limit automatic reclosing on circuits
with elevated fire ignition risk. Currently, 224
protection devices are included in the DLM program.
Figure 21. Fire-Weather Dashboard Results for
September 20-23, 2022
Figure 20. Dry Land Mode Device:
Viper Recloser
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 27 of 59
27 Avista 2023 Wildfire Resiliency Plan
In December of 2020, Avista engineers reviewed the DLM program and made four recommendations:
1. Use of the U.S. Forest Service Wildland Fire Assessment System to determine when to initiate
DLM protocols.
2. Use of the WUI map to determine which circuits should operate under DLM.
3. Enable instantaneous tripping for DLM circuits.
4. Transition to a fully automated DLM system.
Avista has fully incorporated recommendations 1-3 and is working towards a fully automated DLM system
by the end of 2029. Currently, 120 of 224 devices are automated and capable of supporting 3 levels of
protection (base, elevated, and extreme). The remaining 104 devices do not support remote operation
and must be manually switched from the base setting to the extreme mode. These devices will not support
the intermediate, elevated mode. Figure 22 illustrates the various DLM modes and associated reduction
in available fault energy.

During non-fire season (November-May), Avista operates distribution lines to maximize service reliability.
Data indicates that 50% of distribution faults are temporary, such as animal contacts, lightning, and small
tree branches. Temporary faults can be cleared by de-energizing a circuit and then re-energizing a couple
of seconds later. However, if the fault is permanent such as a broken conductor, car hit pole, and when
trees fall into powerlines, a combination of circuit breaker operation and line fuses are used to isolate the
fault and limit the number of impacted customers. As illustrated in Figure 22, operation during non-fire
season produces fault energies that range from 10% (temporary) to 100% (permanent fault on main line).
When the system is transitioned to DLM, base protection levels limit available fault energy to 55%,
essentially reducing fire ignition potential by half. In Base DLM, fuse links remain active and automated
circuit reclosers are limited to a single reclose attempt. Note that the graphic delineates between fully
automated devices and original DLM or manual mode. Manual mode devices will be automated by 2029.
Figure 22. Dry Land Mode Protection Levels
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 28 of 59
28 Avista 2023 Wildfire Resiliency Plan

Avista started upgrading the DLM system in 2021 by adding communications systems to substations,
beginning in St. Maries, Idaho. At present, 100 fire mode ready reclosers have been commissioned with
new DLM settings and 17 new distribution line reclosers have been installed. In total, 120 circuit reclosers,
both in substations and on distribution lines, have been automated with 104 devices remaining.

While many utilities including Avista have initiated wildfire mitigation programs and are investing in grid
hardening and vegetation management programs, electric systems will continue to experience equipment
failures, weather related incidents, and human-caused electric faults. Avista’s Dry Land Mode operating
system is a powerful tool for mitigating fire risk potential.
Situational Awareness Financials
Table 15 indicates actual and projected costs associated automating the DLM system including costs to
develop and maintain the fire-weather dashboard.23

Emergency Response and Operations
Avista system dispatchers and field crews routinely coordinate with emergency first responders, and the
Company’s communication systems continue to adapt and evolve to support emergency operations.
While tremendous progress has been made to partner with fire agencies including community outreach
efforts and fuel reduction programs, three elements remain active in the 2023 Wildfire Plan that support
emergency operations:
• Avista Wildfire Emergency Operating Procedure (EOP)
• Fire Safety Training for Avista 1st Responders
• Expedited Response Agreements

23 Note that once the Dashboard is fully developed and in place, no additional expenditures are anticipated as this becomes a part of routine workloads.
Table 15. Situational Awareness Program Costs
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 29 of 59
29 Avista 2023 Wildfire Resiliency Plan
Wildfire Emergency Operating Procedure (EOP)
Avista uses an Incident Command Structure (ICS) to respond to electric and natural gas emergencies.
This system is activated several times each year in response to severe weather conditions and other
high impact events. Avista Incident Command is focused on coordinating service restoration using a
basic incident command structure including planning, logistics, operations, safety, and finance. As noted
in the 2020 Wildfire Resiliency Plan, Avista plans to expand its EOP to incorporate a specific wildfire
function in order to coordinate with fire officials and assist with cause and origin investigations. However,
restrictions in place during COVID made it difficult to conduct face-to-face meetings. Avista postponed
work on the Wildfire EOP until personnel could meet in person. In 2023, we plan to assemble a team to
develop and document wildfire emergency operating procedures.

Fire Safety Training for Avista 1st Responders
Avista employs approximately 290 electric line operating personnel across 12 operating districts. These
employees respond to a variety of electric trouble calls including those that involve structure as well as
wildland fires. In 2022, in-person training was provided to all electric line personnel with a focus on safety
during wildfire response. A prominent theme in that training was direct contact and coordination with fire
authorities prior to conducting any line inspections or attempting to re-energize portions of electric circuits.
We recognize that in a wildfire event safety comes first, and that police and fire authorities command the
scene. Though Avista crews respond to pole fire events and have basic firefighting training and
equipment, they are not professional firefighters. We defer fully to fire professionals. Annual refresher
training is aimed at reinforcing Avista protocols for fire safety and coordination with fire personnel to
benefit both parties.

Expedited Response Agreements
During development of the 2020 Wildfire Plan, Avista met with several fire
agencies including those in Spokane County. Discussions led to an
agreement whereby Avista transmission operators are directed to notify fire
officials of transmission line faults. In turn, fire agencies dispatch crews to
determine whether the incident resulted in fire activity. This agreement,
known internally as Expedited Response, was piloted during the 2020 and
2021 fire seasons. In 2022, a similar agreement was executed with the
Washington Department of Natural Resources. This allows for a state-wide
approach as opposed to county-by-county agreements. Development of a
similar agreement with the State of Idaho is underway and should be ready for the 2023 fire season.
Wildfire Resiliency Program Costs
Avista is committed to reducing the risk of wildfire by deploying cost-justified and prudent measures.
Wildfire risk is an enterprise-level initiative and is subject to executive management review and approval
when allocating capital and operating budgets. Avista is committed to ensuring that the Wildfire Plan
goals are reasonable and cost-effective based on the best data and science available.

Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 30 of 59
30 Avista 2023 Wildfire Resiliency Plan
Table 16 indicates actual expenditures for 2020 through 2022, and budget level projections from 2023
through 2029. Wildfire Resiliency costs over the 10-year operating horizon reflects a capital investment
of $285.9 million with a corollary operating expense cost estimated $126.4 million dollars. The largest
investments are associated with distribution grid hardening and the risk tree vegetation management
programs. While most capital will sunset at the end of 2029, the majority of operating expenses are
ongoing and are generally related to vegetation management. Capital investments are expected to peak
at $35 million in 2025 and remain at that level through 2029. Operating and maintenance expense is
expected to peak in 2023 and then decline from 2024 through 2029. Vegetation planners expect the
number of dead, dying, and diseased trees to decrease as we work through the initial backlog of hazard
trees identified during 2022 and 2023.
2023 Wildfire Resiliency Plan Summary
Avista is committed to a 10-year strategy to decrease wildfire risk associated with transmission and
distribution line operations and to make the grid more resilient to the impacts of wildfires. In 2022, the
National Interagency Fire Center reported 67 wildfires in close proximity to Avista electric lines. Although
fire activity in 2022 was below the 10-year average, human development continues to occur near forest
landscapes and this proximity to burnable fuels combined with the uncertainties associated with climate
change make wildfire a significant risk for many communities. Table 17 lists key wildfire plan performance
measures recorded from 2018 to 2022.

Table 16. Wildfire Resiliency Program Costs
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 31 of 59
31 Avista 2023 Wildfire Resiliency Plan
A core tenant of the
Wildfire Plan is to
mitigate the number of
ignition potential events
associated with electric
lines. In 2022, 107 spark-
ignition events were
recorded versus the 5-
year average of 117.
Electric pole fires were
significantly lower at 50
versus the 5-year
average of 83. The
number of trees that fell
into lines was about
average, though the
number of trees that
encroached on lines was
lower. Avista completed grid hardening upgrades on 180 miles of electric distribution lines in 2022 and
installed 118 steel poles on transmission lines in high fire risk areas. Overall, Avista continues to make
steady progress towards its long term objective of converting all transmission poles from wood to steel.
In 2022, Avista conducted the first 100% inspection of distribution lines covering 6,466 miles and
employing over 40 arborists. As a result of that effort, nearly 20,000 dead, dying, and diseased trees
were removed near electric lines. Lastly, significant progress has been made to upgrade system
protection devices. To date, 124 devices have been fully automated as part of Avista’s Dry Land Mode
operating system.

Avista recognizes that the threat of wildfire impacts all of us, at our homes, communities and businesses.
Avista is charged with the safely, reliably, and affordably delivering energy services and the 2023 Wildfire
Resiliency Plan serves as a testament to that commitment and responsibility.

Table 17. Wildfire Resiliency Program Costs
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 32 of 59
32 Avista 2023 Wildfire Resiliency Plan
Addendum
2022 Fire Season Recap
In Washington, spring water supply conditions for
2022 were much better than average. In fact, the
state experienced the second-wettest May
through June since 1895. As a result, no part of
Washington experienced more than “moderate”
drought conditions. However, above-normal
temperatures in July through September created
an opportunity for expansion of moderate drought
areas across western Washington. Still, this was
good news compared to 2021, where nearly half
the state was listed in the “exceptional drought”
category. In 2022 Washington State had the
fewest square miles burned in a decade,
following the second- and third-worst fire seasons
on record in 2020 and 2021. Only about 219
square miles burned in Washington state in 2022,
compared to nearly 781 square miles in 2021 and
1,316 square miles in 2020.24 Washington Commissioner of Public Lands, Hilary Franz, stated that
modernized fire equipment, quick responses to fire starts, and increasing forest health programs have
helped reduce catastrophic fire seasons. She reported that in 2022 the Department of Natural Resources
held 94% of wildfires to 10 acres or less.25

Drought conditions were slightly worse in Idaho, especially in the southern part of the state, which saw
very low snowpack into 2022. 2021 was a brutal year for water resources in Idaho, but moisture and
cooler temperatures early this year helped prevent a repeat for 2022. The number of fires Idaho
experienced this year was near normal yet led the nation in number of large fires at 33,26 but with only
about 383 square miles burned,27 significantly below the annual average of nearly 983 square miles.28

24 NYNorthwest/Associated Press, “Washington State’s Fire Season Lightest in a Decade,” October 10, 2022, https://mynorthwest.com/3669778/washington-states-fire-season-lightest-in-a-decade/#:~:text=State%20Commissioner%20of%20Public%20Lands,square%20kilometers)%20burned%20in%202020. 25 Courtney Flatt, “Washington’s 2022 Fire Season Has Been the Mildest in a Decade,” Oregon Public Broadcasting, October 9, 2022, https://www.opb.org/article/2022/10/09/washington-wildfire-season-bolt-creek-fire-goat-rocks-fire-oregon-wildfires/ 26 Luke Randle, “Idaho Leads the US in Large Wildfires, Second in Acres Burned,” September 11, 2022, https://idahonews.com/news/local/idaho-wildfires-leads-acres-burned#:~:text=Idaho%20has%20the%20most%20large,11%2C%202022. 27 Luke Randle, “Idaho Leads the US in Large Wildfires, Second in Acres Burned,” September 11, 2022, https://idahonews.com/news/local/idaho-wildfires-leads-acres-
burned#:~:text=Idaho%20has%20the%20most%20large,11%2C%202022. 28 Idaho Dept. of Environmental Quality, “Idaho Wildfire Emissions Estimates,” January 2022, https://www2.deq.idaho.gov/admin/LEIA/api/document/download/16543#:~:text=These%20estimates%20may%20vary%20from,average%20of%20around%20600%2C000%20acres.
Figure 23. October 2022 Drought Conditions
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 33 of 59
33 Avista 2023 Wildfire Resiliency Plan
Impacts to Infrastructure
In 2022 Avista lost 55 structures (transmission and distribution) to wildfire, though none of the large fires
in our service territory were caused by Avista facilities (as reported by the Washington Department of
Natural Resources.)

The Express Fire, near
the Clearwater River
Casino outside of
Lewiston, Idaho, caused
by lightning, burned
through the Hatwai-Lolo
230 kV transmission
line, but most of this
section has steel poles,
so it suffered no real
damage.

The Lind fire burned
through low grassy
areas and wheat fields
and continued into the
town of Lind,
Washington, where it
destroyed six homes and ten other structures. A local farmer claimed that his combine started this fire
while he was harvesting his wheat. This fire damaged 12 transmission structures on the Lind-Washtucna
line along with 22 distribution poles. Avista stepped up to provide impressive customer service related to
this fire. We initially de-energized powerlines to protect fire crews but re-energized specific areas of
feeders so that
firefighters could
pump water to fight
the fire. Once
conditions were
safe, Avista crews
rushed to replace
the 34 lost
structures, working
through the night to
restore service to
all customers by
the next morning.

Figure 24. Express Fire
Figure 25. Lind Fire
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 34 of 59
34 Avista 2023 Wildfire Resiliency Plan
The Wagner Road fire
was one of the largest
fires in Washington in
2022. It started east of St.
John and burned through
the Lind-Shawnee line.
The official cause is
unknown, but this fire is
suspected to have been
caused by a combine
harvesting wheat. It
burned through
rangeland, stubble, and
standing wheat,
destroying four
outbuildings and 20
Avista transmission
structures. As soon as fire
crews released our people to work in the area, Avista crews from Pullman, Spokane, and Coeur d’Alene
mobilized. It took them only four days to get this line back in service, including working in dust three feet
deep in places and bringing in special equipment to drill through solid basalt to place steel poles.
The Cannon Fire turned out to
be a small fire in a very bad
spot. This fire, caused by a
passing train, started just
south of Interstate 90 near
Latah Creek in a Spokane
residential area. It damaged a
transmission structure on the
Metro-Sunset line but was
suppressed quickly. The
damaged transmission
structure was replaced.

2023 Fire Season Outlook
Long term in the Northwest, the number, size, and severity of wildfires has increased in recent years,
primarily associated with increased temperature and drought, hotter and drier summers (and the
associated drier soils and vegetation), earlier spring melting leading to decreased summer water
availability, and reduced snowpack. These climate changes lead to additional risk factors such as
invasive grasses that provide fuel. Other influences include land use, prior fire suppression practices that
led to increased forest density and fuel levels, invasive species that have damaged the health of trees,
Figure 27. Cannon Fire
Figure 26. Wagner Road Fire
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 35 of 59
35 Avista 2023 Wildfire Resiliency Plan
and the largest factor, human activity, which accounts for 70-90% of wildfires.29 As far as the outlook for
2023, scientists are predicting a La Niña for 2023, the third such winter in a row, meaning the Pacific
Ocean temperatures will be cooler than normal. This typically means a lot of snow and cooler
temperatures for the Northwest, which should help the region reduce or even avoid drought conditions in
2023, which is beneficial in reducing fire risk.30
Continuous Improvement (Lessons Learned)
Challenges of Risk/Hazard Tree Program

With the Wildfire Resiliency Plan, Avista expanded its risk/hazard tree program from cycle trimming (20%
of the system annually) to 100% risk tree inspection and remediation program each year. Vegetation
planners had forecasted the volume of dead, dying, and diseased trees that could potentially strike
powerlines prior to 2022, but when 6,466 miles of distribution powerlines and 2,270 miles of transmission
powerlines were inspected in 2022 – a new record for Avista - the number of risk trees came in at nearly
double earlier estimates. Avista had never before conducted a 100% inspection of risk trees and is finding
that forest health issues are much more dire than anticipated. This situation was made worse by the
historic drought of 2021, but also reflects high impacts on forest health from long term drought, insects,
human activity, disease, weather, and fire, leading to higher levels of tree mortality than expected and
which continue to create spikes in risk trees on the system. In 2022 Avista removed over 17,000 dead,
dying, or diseased trees within strike distance of powerlines. That is a record level of tree removals for
Avista.

Other issues are
also creating
complexity and cost
around meeting our
vegetation goals. As
wildfire risk
reduction has come
to the forefront,
utilities across the
western U.S. are all
competing for the
same vegetation-
related labor
resources. Avista’s primary inspection contractor has repeatedly been unable to recruit and retain enough
inspectors to complete the work. We ended up requiring four times as many inspectors as we had

29 USDA Climate Hub, “Climate Change and Wildfire in Idaho, Oregon, and Washington,” https://www.climatehubs.usda.gov/hubs/northwest/topic/climate-change-and-wildfire-idaho-oregon-and-washington 30 El Niño and La Niña events have wide-ranging impacts, affecting patterns of rainfall, flooding and drought around the Pacific Rim. A La Niña winter tends to be cooler and wetter in the Pacific Northwest, where an El Niño brings winters of low
precipitation, resulting in dry conditions and low snowpack. Three La Niña events in a row has only happened twice since 1950, so it is considered a rare occurrence. Hannah Hickey, “Study Suggests La Niña Winters Could Keep on Coming,” University of Washington, October 3, 2022, https://www.washington.edu/news/2022/10/03/study-suggests-la-nina-winters-could-keep-on-coming/
Figure 28. Deer Park, WA: Beetle Infestation. Photos taken 4 months apart.
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 36 of 59
36 Avista 2023 Wildfire Resiliency Plan
historically used in order to scale up to 100% risk inspection. The Company was required to contract with
four additional vendors to bring enough people to the service territory to allow inspecting the entire
system. And given the level of competition for resources, contractors – if they can be secured - are able
to command 60-hour work weeks, lodging, and per diem allowances, unexpectedly increasing costs for
this critical program.

Avista is also beginning to incorporate remote sensing LiDAR and satellite imagery data into the
vegetation management programs. These are new technologies to the Company and more time,
experience and refinement are needed before they truly begin replacing boots-on-the-ground labor
resources. However, after our initial experience with 100% inspection and subsequent mitigation, and
through the use of these technology tools and gaining confidence in them, risk trees should become more
of a known quantity, making it easier to right size the labor required to complete this work on an annual
basis. As tree fall-in risk represents the highest risk of spark-ignition potential on our system, Avista
remains committed to inspecting 100% of the grid each year.

Implementing Elevated Dry Land Mode (DLM)
Avista entered summer dry land mode operations on July 19th this year and ended in mid-October. This
is consistent with a typical summer, as contrasted to 2021, which was abnormally hot and dry and resulted
in entering DLM a month early.

This year, for the first time ever, we implemented Elevated
Dry Land Mode on two separate days encompassing eight
circuits, potentially impacting just over 8,500 customers in
Washington state. It went off without a hitch. Customers
were identified and notified in advance that they could
potentially experience outages that may be longer than
normal due to our need to patrol the line if it tripped to
ensure there were no fire starts. Fortunately, there were no
events that tripped these circuits and customers
experienced no service interruptions. However, this
experience helped prove the updated Dry Land Mode
concept and that the framework developed for it was effective. All of the impacted Avista groups stepped
up to make this a successful endeavor, helping prove its usefulness in protecting customers from potential
fire events by reducing the chance that our facilities could trip and lead to a fire.
1) July 29: 1 Circuit Elevated in Deer Park.
Impact: 2,000 Customers
2) August 3: 7 Circuits Elevated in Ford –
Gifford, W. Spokane, and Deer Park.
Impact: 6,544 Customers
NO SERVICE INTERRUPTIONS WERE
EXPERIENCED.
Customers were contacted ahead of time
using email, social media channels, and
interactive voice recordings (IVR).
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 37 of 59
37 Avista 2023 Wildfire Resiliency Plan
Transmission Steel Conversion
Construction activity on the Addy-Gifford 115 kV line was completed in early October and will hit its budget
target. The Addy–Gifford transmission line is a 21-mile radial line that was originally constructed as a 60
kV line in 1951 by a rural electric district. Avista acquired the line in 1955 and operated it as a tap off the
old Magnesite–Orin 60 kV line for a time. In 1975 most of the old Magnesite–Orin line was dismantled,
but the section from Orin to Gifford remained in service at 60 kV until the 1980s when the line was
reinsulated to operate at 115 kV and connected to BPA’s Addy Substation. Due to the absence of multiple
sources to serve loads out of Gifford Substation, very little maintenance work has been conducted on
this line since the 1980s.

As part of a 2010 NERC Alert, Avista performed an
aerial LiDAR survey and subsequent line rating
analysis on the Addy–Gifford line which indicated
clearance discrepancies that Avista committed to
mitigate in 2021. Initially, the plan was to conduct a
small project to mitigate these discrepancies.
However, in 2020 Avista’s Wildfire Resiliency
initiative identified much of the Addy–Gifford line as
being within the Wildfire Urban Interface (WUI)
Zone 3 (the highest risk zone). For this reason, the
Addy– Gifford line was identified as a good
candidate to be rebuilt entirely with steel poles.

The inability to support the load at Gifford Sub from
alternate sources makes taking line outages for
maintenance work very difficult. In recent years, Avista’s
Transmission Department has implemented a variety of
solutions to accommodate outages on radial lines, including
planning several short outages and “swarming” the line with
as many crews as possible, building distribution tie-lines to
back-feed radially fed substations, and/or installing
temporary diesel generators and step-up transformers to
feed directly onto the distribution system. Unfortunately,
rebuilding the Addy–Gifford line is too extensive to “swarm”
due to the multiple distribution voltages in addition to the
extremely long feeder lengths, making a distribution tie-line
impractical. Additionally, Avista’s Transmission Department investigated the option of installing a diesel
generator at Gifford Sub, but the operating costs alone were going to be nearly $1 million per month. It
was determined that the most cost-effective and feasible way to perform the work on this line was to work
the line while energized. Avista does not have much experience in energized transmission line work so
contracted with Portello, who is the industry leader in energized transmission work, to perform the first
phase of the Addy–Gifford rebuild. For this phase, all existing wood poles from Gifford Sub to Structure
#9/3 will be replaced with self-weathering steel poles, and the existing conductor will be transferred. All
distribution underbuild crossarms will also be replaced with fiberglass crossarms, and insulators
upgraded to vise-top insulators. The existing line rating will be maintained, but the new poles are designed
to accommodate a future “hot-reconductor” to 795 ACSS “Drake” capable of operating at 200℃.
Figure 30. Addy-Gifford Work
Figure 29. Addy-Gifford Steel Pole Replacement Work
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 38 of 59
38 Avista 2023 Wildfire Resiliency Plan
Glossary of Terms

ADMS: Advanced Distribution Management System. This is the replacement system for Avista’s current
inhouse-created Outage Management System (OMS). It is an enterprise level system. Wildfire is
among many other Company users of this system. The new ADMS will manage and track all planned
and unplanned outages that affect the grid.

Access and Functional Needs (AFN): Customers who are especially vulnerable such as those who
are disabled, dependent on electrically operated medical equipment,
who are transportation disadvantaged, etc.

Animal Guards: Parts installed to act as a barrier to stop animals such as
squirrels and birds from coming into contact with energized power
equipment.

Asset: Electric lines, structures, equipment, or supporting hardware in the
service of providing electric power to customers.

At-Risk Species: Species of vegetation that have an elevated risk of (1) coming into contact with
powerlines, (2) causing an outage or ignition, and/or (3) being easily ignitable and are within close
enough proximity to potential arcing, sparks and/or other utility equipment thermal failures. “At-risk
species” must be a function of species-specific characteristics including growth rate, failure rate of
limbs, trunk, and/or roots (as compared to other species), height at maturity, flammability, vulnerability
to disease or insects, etc.

Backburn/Backfire: A fire set along the inner edge of a fire line to
consume the fuel in the path of a wildfire and/or change the
direction of force of the fire to help get it under control.

Bail Connector: A protection device installed on hot taps to hold the
conductor if the hot tap fails, preventing live conductor from falling
to the ground and potentially starting a fire.

Base Level Dry Land Mode: DLM is a non-reclosing distribution protection scheme used during summer
fire season (typically July and August) on circuits determined to be at risk for fire activity based on a
variety of factors including vegetation, past events, and age of equipment. These circuits are
configured so that when they trip, they will wait for a predetermined length of time then reclose to test
the circuit. This allows the line to go back into service for incidental and transitory faults such as a
tree branch touching the line. If the line tests bad after
the first reclose, it will wait for a predetermined length
of time then test the circuit again. If the line tests bad
the second time, it will stay off until it is manually
inspected to ensure it is safe before it is placed back
in service. This has the goal of balancing reliability and
fire risk potential.
Base Level Dry Land Mode
Animal Guard
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 39 of 59
39 Avista 2023 Wildfire Resiliency Plan
Baseline: A measure, typically of the current state or condition, which establishes a starting point for
comparison with measures from other states or conditions.

Brush: Refers to vegetation dominated by shrubby, woody plants, or low growing trees.

Burning Index: An estimate of the potential difficulty of fire containment, judged by the flame length at
the most rapidly spreading portion of a fire’s perimeter.

CAIDI: CAIDI refers to “Customer Average Interruption Duration Index.” It is calculated as total minutes
of customer interruption divided by the total number of customers interrupted. CAIDI describes the
average time required to restore service. It only includes customers who actually experienced an
interruption.

CAIFI: CAIFI refers to “Customer Average Interruption Frequency Index.” It is calculated by dividing the
number of interruptions by the number of customers experiencing interruptions. It describes how
many interruptions each impacted customer experiences.
CEIP / Clean Energy Implementation Plan: An overview of Avista’s plan for progressing toward the
clean energy requirements of Washington State’s RCW 19.405, the Clean Energy Transformation
Act (CETA).31 This Act requires all retail sales of electricity to Washington retail customers be
greenhouse gas neutral by January 1, 2030. Avista’s CEIP work impacts Wildfire in its efforts to
communicate better with customers, including on wildfire preparation and Dry Land Mode impacts.
Circuit: The path for
transmitting electric current
from the device that creates
the current (generator)
across all associated
equipment (such as the wire
or conductor, switches,
breakers, etc.) to the end user, as shown in the
graphic on the right.
Circuit Mile: The total length in miles of separate circuits regardless of the number of conductors used per circuit.
Circuit Recloser: Circuit reclosers are similar to household breakers. They shut off the power when
trouble has been detected then automatically test the line to see if the trouble has been removed. If the problem is only temporary the recloser automatically resets itself and restores electrical power.
Adding communications to power system circuit reclosers provides monitoring and control

31 RCW 19.405.040: Greenhouse gas neutrality—Responsibilities for electric utilities—Energy transformation project criteria—Penalties. https://app.leg.wa.gov/RCW/default.aspx?cite=19.405&full=true#:~:text=(1)%20It%20is%20the%20policy,customers%20by%20January%201%2C%202045.
Electric Circuit
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 40 of 59
40 Avista 2023 Wildfire Resiliency Plan
functionality, including the ability to operate the
device remotely. By placing circuit reclosers at
strategic locations, Avista Distribution Operations can
re-task those devices during periods of elevated fire
danger to operate in fire protection mode rather than
in their typical reliability mode. In other words, if there
is a high-risk situation, the reclosers can be set to not
automatically reclose.

Complex Fire: As related to fire, this is when two or
more individual fire incidents located in the same
general area are assigned to a single incident
commander or unified fire command and typically
given one name that includes the word “Complex” to
indicate that the fire has individual components.

Condition-Based: Maintenance based on the way equipment is performing, its age, number of times it
was actuated, and/or other factors that indicate the actual condition of an asset.
Consumer Average Interruption Duration Index: CAIDI is the average duration of an interruption,
calculated based on the total number of sustained (over five minutes in length) interruptions in a year.

Control Line: A completed fuel break around the fire. This
break may include natural barriers, manually created
barriers , and/or mechanically constructed fire lines to try
to keep a fire within controllable boundaries.

Cooperating Agency/Partner: For Avista’s Wildfire Program,
this includes external fire professionals, agencies that
provide customer assistance, law enforcement, the Red
Cross, emergency management agencies, state/city/local
government entities, etc. that the Company works with in planning and implementing our Wildfire
Plan.

Critical Facilities/Infrastructure: Referring to outage events, these are elements critical to public safety
such as emergency services, schools, jails/prisons, healthcare and medical services, water, waste
and wastewater systems, communications, some manufacturing, and transportation. Referring to the
utility, these are elements of the electrical grid that are required in order to provide customer service
as well as safety. Critical infrastructure is a priority for restoration of service.

Crown Fire: A crown fire is defined as a fire that has
ascended from the ground into the forest
canopy/treetops and is spreading through it, usually in
conjunction with the surface fuels. When a forest fire
spreads from treetop to treetop it often begins advancing
at great speed, well in advance of the fire on the ground.
Building a Control Line
Crown Fire
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 41 of 59
41 Avista 2023 Wildfire Resiliency Plan
Customer Choice Safe Tree Program: At Avista this has been renamed the “Safe Tree Program.” It is
a partnership with private landowners to remove risk trees, trees which are likely to come into contact
with power lines, but which are located on private property. This program reduces the chances of
their trees contacting powerlines and creating fire potential, improving customer safety and reliability.

Customer Hours: When referring to an outage, this is the total number of customers multiplied by the
average number of hours of a power outage.

Cycle Trimming: At Avista, routine vegetation management divides the system into five segments which
are patrolled on a rotating five-year basis, meaning about 20% of the system is inspected and subject
to trimming each year. The Wildfire program added a 100% risk tree inspection to non-urban areas
in addition to the routine cycle trimming vegetation program to more rapidly address vegetation issues
that may lead to fire.

Danger Tree: At Avista, a danger or risk tree is a dead,
dying, or diseased tree, or a tree that has a structural
defect or lean that makes it likely to fail in whole or in part
and contact electrical equipment or facilities within or
adjacent to the utility right- of-way.

Dead Fuels: Fuels with no living tissue, so moisture
content is governed almost entirely by atmospheric
moisture (relative humidity and precipitation).

Dead Fuel Moisture: Moisture content of dead
vegetation, which responds to current environmental
conditions and is critical in determining fire potential.

Defensible Space: An area, either naturally or human-made, where material capable of causing a fire to
spread has been treated, cleared, reduced, or changed to act as a barrier between an advancing
wildland fire and the loss of life, property, or
resources. In practice, “defensible space” is
often defined as a buffer, an area a minimum
of 30 feet around a structure that is cleared of
flammable brush or vegetation. In forested
areas, this buffer area typically increases to
100 feet of space.

Digital Data Collection: At Avista, this means
collecting LiDAR and satellite images of our
transmission and distribution systems in order
to help pinpoint vegetation and other encroachments, which allows planning field work and mitigating
problematic vegetation more accurately.

Dispatcher: A person who receives reports of discovery and status of outages, confirms their locations,
and takes action to provide people and equipment likely to be needed, sending them to the proper
place.
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 42 of 59
42 Avista 2023 Wildfire Resiliency Plan
Distribution (DX): Electric facilities that have a voltage that is 60 kV or lower.

Distribution Automation: Avista’s Wildfire program designed to aid in implementing wildfire protection
measures. This program will fund upgrading or replacing 240 devices (including about 50 midline and
substation breakers) to enable dynamic protection settings, allowing these devices to be operated
remotely and automatically during fire season to support Avista’s Dry Land Mode operations, reducing
fire risk.

Distribution Grid Hardening: Avista’s Distribution Grid Hardening Program targets portions of circuits
located in high-risk fire areas with the goal of reducing spark ignition outages. This work includes
replacing wood crossarms with fiberglass units, replacing end-of-life wood poles, changing out
obsolete small copper wire with modern steel reinforced aluminum wire, installing wildlife guards to
reduce animal related events, eliminating open wire secondary districts, installing wedge connected
stirrups to provide protection and additional strength at hot tap connection points, and undergrounding
conductor when cost-justified.

Distribution Infrastructure Upgrades: In Avista’s Wildfire Plan, this means making improvements to
our distribution system including adding wildlife guards, replacing wood crossarms with fiberglass,
replacing wood poles with steel in specific locations, and replacing replaced obsolete equipment that
has known spark potential. These changes are designed to reduce the potential for sparks.
Drip Torch: A hand-held device for igniting fires by dripping flaming
liquid fuel on the materials to be burned. It consists of a fuel fount,
burner arm and igniter. Fuel used is generally a mixture of diesel and
gasoline. This tool is used to create back burns to help control a fire’s
spread.

Drought Index: A number representing net effect of evaporation,
transpiration, and precipitation in producing cumulative moisture depletion in the soil.

Dry Land Mode: DLM is a non-reclosing distribution protection
scheme used during summer fire season (typically July and August)
on circuits determined to be at risk for fire activity based on a variety
of factors including vegetation, past events, and age of equipment.
These circuits are configured so that when they trip, they will wait for
a predetermined length of time then reclose to test the circuit. This
allows the line to go back into service for incidental and transitory
faults such as a tree branch touching the line. If the line tests bad after
the first reclose, it will wait for a predetermined length of time then test
the circuit again. If the line tests bad the second time, it will stay off
until it is manually inspected to ensure it is safe before it is placed back
in service.

Dry Land Mode Automation: Avista’s plan to upgrade 240 midline
and substation devices in areas at risk for wildfire to enable the
devices to be operated remotely and automatically in response to fire
situations. Avista’s Dry Land Mode Steps
Drip Torch
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 43 of 59
43 Avista 2023 Wildfire Resiliency Plan
Emergency Operations Procedures (EOP): Defines key roles and responsibilities for personnel,
identifies communications channels, and outlines strategies for engaging with fire protection
professional and emergency operating agency staff during expected or actual wildfire events, creating
a consistent approach.

Elevated Dry Land Mode: Circuits whose
fire risk exceeds nominal levels are
modified to increase the protection
level. This is similar to Base DLM but
instead of a time delay tripping step,
the circuit will instantly trip if it tests bad.
This allows service restoration for temporary faults but will de-energize the entire circuit for permanent
faults by tripping off the breaker.

Elevated Fire Threat Areas: Known as WUI Tiers 2 and 3, these are areas in which there is a higher
risk for the ignition and rapid spread of wildfires as well as increased human safety and infrastructure
risks due to the tendency for strong winds, abundant dry vegetation, significant levels of human
activity and habitation zones, and other environmental conditions.
Elevated Wildfire Risk: This means that based on existing weather and vegetation conditions, wildfires
are possible should ignitions occur.

Emergency First Responder Training: Protects both firefighters and utility workers in the event of a fire
event by providing proper training in response to both, mitigating the safety risks. Utility workers are
trained in fire response and safety, and fire professionals are trained in utility operations, equipment,
and power equipment safety.

Emergency Operating Program (EOP): An EOP is a command structure that shifts normal operations
to emergency response, with service restoration typically the primary objective. For a Wildfire EOP,
the primary focus is safety, and the engagement includes outside fire and emergency-related entities
to prepare for potential or actual wildfire events.

Episodic Wildfires: Wildfires that do not occur frequently or regularly.

Expedited Fire Response: In Avista’s Wildfire Plan, this is an agreement with local firefighting agencies
that sends fire crews directly to the site of a transmission trip event to ensure if there is a fire, it is
managed immediately.

Extreme Dry Land Mode: Circuits whose fire risk is judged to be
extreme are configured in a way similar to the crew safety mode
called “Hot Line Hold.” In this configuration, auto reclosing is
disabled, and instantaneous tripping is enabled. A circuit that
experiences a fault will trip off and stay off at the first instance. It does
not test or try to reclose. The circuit must be manually inspected to
ensure it is safe before it is placed back in service.

Extreme Dry Land Mode
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 44 of 59
44 Avista 2023 Wildfire Resiliency Plan
Extreme Fire Behavior: "Extreme" implies a level of fire behavior that ordinarily precludes methods of
direct control action. One or more of the following is usually involved: high rate of spread, prolific
crowning and/or spotting, presence of fire whirls, and/or a strong convection column. Predictability is
difficult because such fires often exercise some degree of influence on their environment and behave
erratically, often dangerously.

Extreme Wildfire Risk: Based on existing weather and vegetation conditions, a large, rapidly growing
wildfire is possible should ignition occur.

Fault Reduction: Decrease the number of faults by prioritizing reliability programs that strengthen the
utility’s infrastructure, especially in higher wildfire risk areas.

Fiberglass Crossarms: Pole fires are a well understood
phenomena within the electric utility community. Electric
current tracking on wood poles and crossarms, especially
during summer months, leads to increased rates of pole fires.
Fiberglass crossarms reduce or eliminate electric current
tracking and hence, pole fires. Fiberglass crossarms are
smooth and resistant to contamination, do not rot or degrade
over time, and are much lighter while being up to six times
stronger than wood. In addition, fiberglass crossarms are
inherently self-extinguishing, so perform well in fire situations.
Fire Behavior: The manner in which a fire reacts to the influences of fuel, weather, and topography.
Installing a fiberglass crossarm
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 45 of 59
45 Avista 2023 Wildfire Resiliency Plan
Fire Behavior Forecast: A prediction of probable fire behavior, usually prepared by a fire professional,
in support of fire suppression or prescribed burning operations.

Fire Behavior Index: A scale that captures fire severity as a function of flame length (intensity of burn)
and rate of spread.

Fire Break: A natural or constructed barrier used to stop
or check fires that may occur or to provide a control
line from which to work to extinguish a fire.

Fire Front: The part of a fire within which continuous
flaming combustion is taking place. The fire front is
usually assumed to be the leading edge of the fire
perimeter. In ground fires, the fire front may be mainly
smoldering combustion.

Fire Ignition Events: In Avista’s Wildfire Plan, this is
when a spark is created by the interaction of utility equipment and its surroundings (such as when a
tree falls into a powerline) and this results in a spark that, under the right circumstances, could
become a fire.
Fire Mode Ready Devices: Midline and substation devices located in high risk fire areas that Avista’s
Wildfire Program will upgrade or replace to allow protection settings to be operated remotely and
automatically in reaction to wildfire or wildfire risk situations.

Fire Mesh Wraps: Avista uses Genics Fire Mesh, a wire mesh treated with
intumescent graphic that, when exposed to extreme heat, rapidly
expands to form a barrier between the fire and the wood pole. These
wraps help prevent low-burning fires from accessing wood poles,
protecting them from damage or destruction.

Fire Perimeter: The entire outer edge or boundary of a fire.

Fire Prone Area: Areas where fires are most likely to
occur or which have a higher tendency for fires to
occur, often as a result of drought, forest health issues
or insect infestations, human interaction, large
amounts of dry undergrowth, low levels of humidity,
etc.

Fire Retardant: Avista uses two primary forms of fire
retardant on the transmission system. Fire resistant
paint has historically been painted on wood
transmission structures near ground line, which is an
effective means of preventing damage caused by
ground fires. This product must be re-applied every 3-5 years. Fire resistant mesh is a new product
Crews bulldoze a fire
break at the fire’s edge
A piece of fire
mesh wrap

Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 46 of 59
46 Avista 2023 Wildfire Resiliency Plan
the Company is switching to. It is chemically reactive to extreme heat, expanding to protect wood
poles from fire. This product does not require ongoing maintenance and is quick and easy to apply.

Fire Risk Potential: This incorporates weather and fuels information to rate the overall fire threat at a
particular location as well as a fire’s likely behavior should one start.

Fire Season: The time of year that wildfires are most likely to take place for a given geographic region
due to seasonality, historical weather conditions, vegetative characteristics, etc.

Fire Threat Conditions/Fire Danger Rating: This considers current and antecedent weather, fuel types,
and both live and dead fuel moisture to estimate the likelihood of a fire occurring as well as potential
fire behavior should a fire occur.

Fire Threat Areas: Areas which have the highest likelihood of impacting people and property and where
additional action may be needed to reduce wildfire risk. Threat level is based on elements such as
population, topography, vegetation type, and historical fires in the area.
Fire Weather: Weather conditions that influence fire ignition, behavior, and suppression.
Fire Weather Dashboard: This is Avista’s primary means of determining fire risk across our system. It
is a risk-based computer program that combines the National Weather Service 7-day weather
forecast with Avista equipment performance as well as time of year, drought conditions, type of
vegetation and moisture levels, sustained wind and wind gusts, and more. It indicates the risk level
for the upcoming week and highlights the maximum expected daily risk, helping the Company plan
accordingly.

Fuel: Combustible material. This includes vegetation such as grass, leaves, ground litter, plants, shrubs
and trees that can feed a fire.
Fuel Concentration/Density: Mass of fuel (vegetation) per area which could combust and result in a
wildfire.
Avista’s Fire Weather Dashboard (Example)
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 47 of 59
47 Avista 2023 Wildfire Resiliency Plan
Fuel Management: Removing, thinning, or otherwise altering vegetation to reduce the potential rate of
propagation or intensity of wildfires.

Fuel Moisture Content: Amount of moisture in a given mass of fuel (vegetation), measured as a
percentage of its dry weight.

Fuel Reduction: Manipulation, including removal of fuels (vegetation management) to reduce the
likelihood of ignition and/or to lessen potential damage and resistance to fire control.

Fuel Reduction Partnerships: In Avista’s Wildfire Plan, this is partnering with external land
management agencies and leveraging funding to remove fuels near Avista facilities. Sharing the cost
allows both parties to do more work than each could accomplish with individual budgets.

Grid: General design of an electric system, whether looped or radial, with consequences for reliability
and ability to support de- energization (e.g., being able to deliver electricity from an additional source
if a line goes out of service). The purpose of the grid is to serve electric power to customers.
Grid Hardening: Actions such as equipment upgrades, maintenance,
and planning for more resilient infrastructure, taken in response to
the risk of undesirable events (such as outages or wildfires) or
undesirable conditions (such as unreliable equipment) of the
electrical system in order to reduce or moderate those events and
conditions, maintaining reliability and safety. This is informed by an
assessment of the relevant risk drivers or factors. In the Wildfire
Plan, this specifically means adapting transmission and distribution
materials and construction to minimize the potential for utility-
involved fires in addition to protecting utility infrastructure in the
event of a fire.

Hazard Tree: A dead, dying, or diseased tree or one which has a
structural defect that makes it likely to fail into energized facilities
whole or in part. Also called a “risk tree,” this is a tree with the potential of imminent fall-in hazard to
energized facilities located inside our just outside of our rights-of-way.

Herbicides: Typically used on the right-of-way to control incompatible tall growing species and noxious
weeds. For the past several years, herbicide applications have primarily consisted of treating the
stumps of fast-growing deciduous trees after they are removed to prevent resprouting. These
applications are recorded within the same work records as the tree removals, generally categorized
as risk tree work.

High Risk Fire Areas: These are areas that have been identified as most at risk for wildfire and
associated damage, such locations in wildland urban interfaces (WUI zones) for which there is little
or no fire protection (typically rural or remote areas), have human population and/or structures, and//or
which have experienced historical wildfires.

High Value Locations: In Avista’s Wildfire Plan, this refers to situations where wood poles are replaced
with steel to add strength and durability at high value or high consequence locations such as high-
Grid
Hardening
Work
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 48 of 59
48 Avista 2023 Wildfire Resiliency Plan
volume traffic areas, railroad, highway, and river crossings, at hard angles, or if access for
maintenance is particularly difficult. These are locations where mechanical or fire-related pole failures
could lead to increased safety risks and reliability impacts.

High Wind Warning (HWW): Level of wind risk from weather conditions as declared by the National
Weather Service (NWS).

Hot Tap: A connection to the utility’s powerline.
A hot tap is a connection that can easily be
removed versus a wedge connector, which
is more permanent. The traditional hot line
tap is attached via a bolt. Over time this type
of connection can come loose and arc and
spark and can melt through the conductor,
dropping it to the ground. Thus, adding parts
such as hot tap connectors that keep the
conductor from falling may help prevent
fires.
Ignition probability: The relative possibility that an ignition will occur, quantified as a number between
0% and 100% (where 0% indicates impossibility and 100% indicates certainty). The higher the
probability of an event, the more certainty there is that the event will occur. (Often informally referred
to as likelihood or chance).

Impact/Consequence of Ignitions: The effect or outcome of a wildfire ignition upon objectives, which
may be expressed by terms including, although not limited to, maintaining health, and safety, ensuring
reliability, and minimizing economic and/or environmental damage.

Incident: In Wildfire Plans, this refers to human-caused or natural occurrence, such as wildland fire, that
requires emergency service action to prevent or reduce the loss of life or damage to property or
natural resources.

Incident Command Structure: The combination of facilities, equipment, personnel, procedures, and
communications operating within a common organizational structure with responsibility to manage
assigned resources to effectively manage an incident.

InciWeb: This is the Interagency All-Risk Incident Information Management System that provides a single
source for fire incident related information and a standardized reporting tool for public use.
Infrastructure: This refers to the equipment Avista utilizes in order to serve customers, including poles,
transformers, conductor, switches, substations, etc.

Inherent Risk: At Avista, this is the current state wildfire risk level which reflects Company wildfire
defense strategies already in place.
Hot Tap Connectors
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 49 of 59
49 Avista 2023 Wildfire Resiliency Plan
Ladder Fuels: Fuels which provide a vertical path between the
ground strata and higher vegetation, allowing fire to carry from
surface fuels into the crowns of trees or shrubs with relative ease.
They help initiate and assure the continuation of crowning when
the fire spreads very rapidly from treetop to treetop.

LiDAR: Light Detection and Ranging, sometimes called 3-D laser
scanning, that can be used to make high resolution
representations of the earth’s surface. At Avista it is used on the
transmission system to identify vegetation encroachment and risk
trees. It works well for transmission due to the open linear
transmission rights-of-way. LiDAR is primarily collected via
helicopter and fixed wing aircraft.

Line Miles: The number of miles of transmission and/or distribution
line. Differs from circuit miles because individual circuits, such as
the two circuits of a double-circuit line, are not counted separately
in circuit miles but are counted as separate in line miles.
Live Fuel Moisture Content: Moisture content within living vegetation
which can retain water longer than dead fuel.

Medical Baseline Customers: Residential customers with qualifying
medical conditions and/or depend on power for qualifying medical
devices for certain medical needs. For example, customers that
have specific heating and cooling or mobility needs, those on
respirators or dependent upon other electrically operated medical
equipment.

Member of the Public: Any individual not employed by the utility.

Managed Risk: At Avista, this is the future state wildfire risk level as it is impacted by the addition of
Wildfire Resiliency elements like grid hardening.

Metrics: In Avista’s Wildfire Program, these are measurements that track how much utility wildfire
mitigation activity has changed the conditions of utility wildfire risk exposure or the ability to manage
and reduce wildfire risk.

Midline Circuit Reclosers: Often used on long distribution lines where
substation-based equipment cannot adequately protect the entire length
of the circuit. Avista’s Wildfire Plan adds communications to these midline
circuit reclosers in order to provide monitoring and control functionality,
including the ability to operate the device remotely. By placing automated
midline circuit reclosers at strategic locations, Avista Distribution
Operations can re-task those devices during periods of elevated fire
danger to operate in fire protection mode rather than in their typical
LiDAR Image
Ladder Fuel
Diagram
Viper Circuit Recloser
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 50 of 59
50 Avista 2023 Wildfire Resiliency Plan
reliability mode. In other words, if there is a high-risk situation, the reclosers can be set to not
automatically reclose.

Miles Completed: In Avista’s Vegetation Management Program, this is a calculated value that equates
to the known overhead line mileage within a polygon multiplied by the percentage of planned work
completed within that polygon. Completion of planned work means executing the plan (trimming,
removing, replacing) to the Company’s specifications.

Miles Patrolled: Miles patrolled and miles planned effectively mean the same thing within the vegetation
work plans.

Miles Planned: Miles patrolled and miles planned effectively mean the same thing within the vegetation
work plans.

Mitigation: A measure or activity proposed or in process that is designed to reduce the
impact/consequences and/or the likelihood/probability of a risk event such as wildfire.
Momentary Outage: The IEEE defines “momentary” outages as a brief loss of power caused by the
opening and closing operation of an interrupting device that are less than five minutes in length.

Multi-Agency Coordination/Partnerships: A generalized term which describes the functions and
activities of representatives of a variety
of involved agencies and/or jurisdictions
who come together to make decisions
regarding the prioritizing of incidents,
and the sharing and use of critical
resources. Also refers to agencies who
work together, sometimes via financial
assistance, in reducing fire risk.

Normal Fire Season: A season or time of
year when weather, fire danger, and
number and distribution of fires are about average.

Old Dry Land Mode: This is a program implemented by Avista in the early 2000s, when, during the
summers, Avista changes the distribution system to turn off automatic re-closing when a fault occurs
in certain parts of the system.

OMS/OMT: Outage Management System or Outage Management Tool. This is an Avista inhouse
developed tool for tracking electric outage cause information (such as car hit pole, tree fall-in, wind,
pole fire, etc.) as well as time stamp, reason, type, number of customers impacted, and length of
outage. The OMS was designed to record actual events based upon cause, not impact, with the goal
of repairing or replacing equipment that has or could lead to an outage. The current OMS does not
include provisions for tracking outcomes beyond direct customer impacts, so is not set up to capture
if an outage results in a fire unless that is noted in Dispatcher comments.

Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 51 of 59
51 Avista 2023 Wildfire Resiliency Plan
Open Wire Secondary Districts: Three conductors with
120/240 volts that run pole to pole below the primary
conductors (primary conductors are on top of the pole in an
overhead distribution system). It is called “open wire”
because the three wires are clearly visible as opposed to a
design in which the three conductors are bundled together.

Outstanding Plan: A still-to-be-completed plan. As inspections
are performed, plans are created that consist of one or more
units of work that need to be performed. In Avista’s
Vegetation Management, this can mean that completion of
a plan is delayed due to customer permission, access,
inclement weather, etc.

NIFC/National Interagency Fire Center: Located in Boise, Idaho, this is the home to the National
Interagency Coordination Center (NICC) and National Multi-Agency Coordination (NMAC) group
which provide unified guidance to fire agencies across the U.S., coordinate fire response and manage
firefighting resources, and track and document fires, sources, size, and impact.
Patrol: Visual inspection of applicable utility equipment and structures that is designed to identify obvious
structural problems and hazards.

Patrol Inspection: A visual inspection of applicable utility equipment and structures that is designed to
identify obvious structural problems and hazards.

Peak Fire Season: That period of the fire season during which fires are expected to ignite most readily,
to burn with greater than average intensity, and to create damages at an unacceptable level.

Plan-Do-Check-Adjust: A continuous improvement technique also known as the Deming Circle or
Shewhart Cycle. Avista’s Wildfire program uses this technique to help continue to grow and improve
the program.

Planned Outage: Electric outage announced ahead of time by the utility.

Pole Fires: Pole fires are a significant contributor to wildfire risk. The
mechanism that causes pole top fires is well-known. This issue is related
to periods of hot, dry weather when insulators become covered with dust
and other contaminants, creating a path for leakage current, which
happens as insulating properties of overhead equipment break down.
Leakage current is usually invisible and does not cause a heat signature,
making it almost impossible to detect. A light rain after the dry spell
increases this leakage current and creates the right conditions for pole fires
when the leakage current is concentrated between wood-to-wood contacts such as the contact point
between wood crossarms and wood poles. Wood shrinkage and cracking around metal bolts holding
wood crossarms to poles form a combustive-friendly cavity for arcing and burning, and the burning
process accelerates when the moisture of wood increases. Fiberglass crossarms virtually eliminate
pole fires. Avista has been installing fiberglass crossarms since the early 2000s. As part of Wildfire
Pole Fire
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 52 of 59
52 Avista 2023 Wildfire Resiliency Plan
Resiliency, the Company has an additional focus on replacing wood
crossarms on structures located in elevated fire areas.

Pole Wraps: Avista uses Genics Fire Mesh, a wire mesh treated with an
intumescent coating that, when exposed to extreme heat, rapidly expands
to form a barrier between the fire and the wood pole. These wraps help
prevent low-burning fires from accessing wood poles, protecting them
from damage or destruction. Mesh is more durable than the fire-resistant
paint and is considerably less expensive than replacing a wood pole with
steel. At Avista, pole wraps are used in areas subject to routine grassland
or sage-shrub fires, areas of low vegetation.

Polygons: Between 2017 and 2018 Avista’s Vegetation Management planning was changed from circuit
level to polygon level. Polygons contain many circuits. Prior to switching to the polygon method, the
overhead line mileage of a circuit was multiplied by the percentage of the circuit planned/inspected
to arrive at “Miles Planned” and the percentage of the work on the circuit completed was multiplied
by overhead line mileage to arrive at “Miles Completed.”

Polygon Planned Work Completed: A polygon that has 100 percent “Miles Planned” and 100 percent
“Miles Completed” requires no further remediation – all tree work has been completed. It is technically
possible that an inspection could lead to no work needed at all, but it is not something that has been
encountered in practice at Avista.
Polygon Planned Work Not Done: The entire Vegetation Management polygon has been
planned/inspected but tree work is incomplete. This category helps keep track of inspections and
work spanning between two plan years, so that those polygons will be carried into the following year
for completion.

Preparedness: Condition or degree of being ready to cope with a potential fire situation.

Preventive Maintenance (PM): The practice of maintaining equipment on a regular schedule based on
risk, elapsed time, run-time meter readings, or number of operations. The intent of PM is to “prevent”
maintenance problems or failures before they take place by following routine and comprehensive
maintenance procedures. The goal is to achieve fewer, shorter, and more predictable outages.

Priority Essential Services: Critical first responders, public safety partners, critical facilities and
infrastructure, operators of telecommunications infrastructure, and water utilities/agencies that are
often prioritized in power restoration in order to protect public safety and welfare.

Public Safety Power Shutoff (PSPS): When electric companies preemptively turn off the power to
specific areas of the system to reduce the risk of wildfires and to help keep customers and
infrastructure safe. These events differ from typical outages because they are based on a prediction
of risk rather than the occurrence of an actual event.

PSPS Event: Defined as the time from when the first public safety partner is notified of a planned public
safety de-energization to the final customer being re-energized.

Installing Pole Wraps
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 53 of 59
53 Avista 2023 Wildfire Resiliency Plan
PSPS Risk: The potential for the occurrence of a PSPS event expressed in terms of a combination of
various outcomes of the event and their associated probabilities.

Rate of Spread: The relative activity of a fire in extending its horizontal dimensions. It is expressed as
the rate the total perimeter of the fire is growing, as rate of forward spread of the fire front, or as rate
of increase in area, depending on the intended use of the information. Usually, it is expressed in acres
per hour for a specific period in the fire's history.

Reburn: The burning of an area that has been previously burned but that contains flammable fuel that
ignites when burning conditions are more favorable.

Red Flag Warning (RFW): A term used by fire weather forecasters to alert the public to an ongoing or
imminent critical fire weather pattern.

Relative Humidity: The ratio of the amount of moisture in the air to the maximum amount of moisture
that air would contain if it were saturated.
Reliability: Maintaining customer service continuity.
Right Tree Right Place: At
Avista this has been renamed
the “Safe Tree Program.” It is
a partnership with private
landowners to remove risk
trees on their private property
that are at risk of coming into
contact with powerlines and
creating fire potential or loss
of reliability and replacing
these trees, if the customer
desires, with a lower growing
variety.

Risk Based: Making decisions based upon how much risk is involved. Typically, a utility identifies specific
risks to safety elements, financial well-being, customer reliability impacts, probability of occurrence,
and consequence of occurrence in order to develop programs and plans which seek to reduce those
risks.

Risk-Based Vegetation Inspections: A new goal based on the Company’s Wildfire Plan that requires
100% of non-urban areas to be inspected for vegetation issues each year.

Risk Event: An event with probability of ignition, including wires down, contacts with objects, line slap,
events with evidence of heat generation, and other events that cause sparking or have the potential
to cause sparks or fire.

Risk Tree: At Avista, a “risk tree” is a dead, dying, or diseased tree or one with obvious structural defects
that has the potential of imminent fall-in hazard to energized facilities.
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 54 of 59
54 Avista 2023 Wildfire Resiliency Plan
Routine Vegetation Inspections: As opposed to risk-
based vegetation inspections, routine inspections consist
of cycle-based tree trimming, focused on about 1,500 miles
(20% of the system) annually.

Right-of-Way (ROW) Work: ROW work means re-
clearing/reclaiming the right-of-way with planning and
completion of work at the span (from one pole to the next)
level as opposed to spot work planned and completed at
the individual tree level.

Run-to-Failure: A maintenance approach that replaces
equipment only when it fails.

SAIDI: SAIDI refers to “System Average Interruption Duration Index.” It is calculated by multiplying the
average duration of customer interruptions by their total number and then dividing by the total number
of customers in the system. SAIDI describes the total duration of the average customer interruption.

Safe Tree Program: This is a partnership with private landowners to remove risk trees to reduce the
chances of their trees contacting powerlines and creating fire potential or loss of reliability. Avista will
replace these trees, if the customer desires, with a low growing variety.

Safety Hazard: A condition that poses a significant threat to human life or property.

Satellite Imaging: In Avista’s Wildfire Plan, this means using satellites to capture images of the
distribution system to detect vegetation issues and changes in vegetation over time. Satellite-
powered artificial intelligence systems such as that used by Avista’s LiDAR and satellite contractors
can predict vegetation growth years in advance. Satellite imaging works well for the distribution
system, which is more widespread and convoluted than the transmission system and is located in a
wide variety of environments not always accessible or visible from the aircraft used to collect LiDAR
images.

Situational Awareness: Many of Avista’s circuit breakers cannot be remotely operated and require
manual intervention to make changes to settings or to identify an issue. This may take several hours
depending on location and crew availability. Avista’s Wildfire Situational Awareness Program funds
communications and control equipment that will help us have “eyes” on critical equipment out in the
field as well as be able to control it remotely in case of fire or high fire threat conditions.

Span: The space between adjacent supporting
poles or structures on a circuit consisting of
electric lines and equipment.

Spark Ignition Event: A situation when
something such as equipment failure
creates a spark that can potentially lead to
a fire.

Risk
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 55 of 59
55 Avista 2023 Wildfire Resiliency Plan
Spark Ignition Potential: The risk of heat (usually via spark or arc) creating the ability for a fire to start,
spread, and do damage.

Spark Ignition Source: Something that creates a spark that may lead to a fire under the right
circumstances, such as a failed piece of equipment, blown fuse, or conductor that touches dried
vegetation on the ground.

Steel Conversion: One of Avista’s wildfire
resiliency strategies is to replace wood
transmission poles in areas at an elevated
risk of fire with steel, as steel is less likely
to be damaged and fail when exposed to
fire.

Substation SCADA / Substation Dry Land
Mode Automation: Provides automation
that allows remote control and operation of
substation equipment to allow it to respond
more quickly if fire conditions indicate
elevated risk. In Avista’s Wildfire Plan, fifteen remote substations located in high fire risk areas will
be upgraded with communications equipment and hardware/software that allows them to support fully
automated Dry Land Mode operations.
Supervisory Control & Data Acquisition: SCADA systems are used to monitor and control a variety
of critical infrastructure in manufacturing, power generation, and other complex circuit infrastructure.
It provides the ability, for example, to monitor and control reclosers to isolate and/or reroute power
during outages or fire events. SCADA provides insights for operators into the operation of the system
in addition to helping them remotely control it.

Surface Fuels: Loose surface litter on the soil surface, normally consisting of fallen leaves or needles,
twigs, bark, cones, and small branches; also grasses, forbs, low and medium shrubs, tree seedlings,
heavier branches, downed logs, and stumps interspersed with or partially replacing the litter. These
elements can feed a fire.

Sustained Outage: The IEEE defines a sustained outage as a disruption in power supply lasting more
than five minutes.

System Average Interruption Duration Index (SAIDI): SAIDI is a system-wide tally of the total number
of minutes per year of sustained outage per customer served.

System Average Interruption Frequency Index (SAIFI): SAIFI is the average number of sustained
interruptions per customer during the year.

Third-party Contact: Contact between a piece of electrical equipment and another object, whether
natural (such as a tree branch) or human (such as a vehicle).

Fire went through Avista’s transmission
lines. Steel (on the left) was undamaged;
wood (on the right) was destroyed.
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 56 of 59
56 Avista 2023 Wildfire Resiliency Plan
Tiers: In Avista’s Wildland Urban Interface, the power system is divided into sections based upon the
risk of a fire occurring and having impact. These are called Tiers and include: Tier 0 (Low or no risk),
Tier 1 (Moderate), Tier 2 (Elevated), and Tier 3 (Extreme).

Transmission: Electric facilities that have a voltage that is 60 kV or above.

Transmission Corridor: The right-of-way associated with a
transmission line in which the utility has the right to remove vegetation
that may interfere with the line.

Transmission Line Inspection: Avista uses ground patrols, aerial
inspections, and LiDAR data to inspect their transmission lines and
structures each year.

Transmission Steel Conversion: Avista’s effort to replace wood poles
specifically in areas with elevated fire risk with steel poles to protect
both infrastructure and customer reliability. The Company has
experienced wildfire burning through steel pole lines with no impact
from the fire.

Tree Fall-In: Trees (or limbs) that are
dead, dying, or damaged by illness, trees impacted by storms,
lumberjacks, etc. that fall and come into contact with powerlines, often
causing an outage.

Tree Grow-In: Trees planted under powerlines that over time grow into and
contact those lines.

TX: Short for Transmission.

Undergrounding: In Avista’s Grid Hardening efforts, select portions of
overhead line will be converted to underground facilities where feasible
and cost justified. Converting facilities to underground fully mitigates
potential spark-ignition risk.

Unplanned Outage: Electric outage that occurs with no advance notice
from the utility.

Utility-Related Ignitions: Ignitions involving utility infrastructure or utility employees as determined by
official investigation to have originated from utility infrastructure.

Vegetation Issues: This typically means trees and other vegetation that has the potential to or has
contacted powerlines.

Vegetation Management, Routine: Trimming, removal, and other remediations of vegetation used to
maintain utility rights-of-way and reduce the risk of outages, ignitions, or other disruption and danger.
Transmission Corridor
Tree Fall-In
Tree Grow-In
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 57 of 59
57 Avista 2023 Wildfire Resiliency Plan
At Avista, routine vegetation management is done on a five-year cycle with 20% of the system
completed each year.

Vegetation Management, Risk-Based: Under Avista’s Wildfire Plan, risk tree inspections are increased
to 100% of non-urban polygons in an effort to mitigate the potential for vegetation to contact
powerlines and create an outage or spark event.

Vegetation Risk Index: Risk index indicating the probability of vegetation- caused outages and/or
ignitions along a particular circuit, based on the vegetation species, density, height, growth rate, etc.

Wedge Connected Stirrups: The traditional hot line tap is
attached via a bolt. Over time this type of connection can
come loose, arc and spark, and melt through the
conductor, dropping it to the ground. The wedge
connected stirrup device prevents the hot tap from being
directly connected to the conductor. The stirrup attaches
in such a way that if the connection loosens and if the
stirrup melts, the conductor is still intact and does not fall
to the ground. A wedge connected stirrup is a more
permanent connection to the powerline than a hot tap.
Wildfire Impact/Consequence: The effect or outcome of a wildfire affecting, although not limited to,
health, safety, reliability, economic and/or environmental damage.

Wildfire Mitigation Plan: A thoughtful approach to addressing the utility’s responsibility in helping
prevent their equipment from starting a wildfire, while at the same time protecting assets paid for by
customer and designed to provide them with reliable service from the impacts of wildfire.

Wildfire Programs: Activities, practices, and strategies that are only necessitated by wildfire risk,
unrelated to or beyond that required by minimum reliability and/or safety requirements. Such
programs are not indicated or in common use in areas where wildfire risk is minimal (e.g., territory
with no vegetation or fuel) or under conditions where wildfires are unlikely to ignite or spread (e.g.,
when rain is falling).

Wildfire Risk: The potential for the occurrence of a wildfire event expressed in terms of ignition
probability and wildfire impact/consequence, and the likelihood that an ignition will grow to become a
large or rapidly growing wildfire due to dry vegetation and weather conditions.

Wildfire Risk Reduction: The average percentage difference between the current state of risk and future
state risk levels as wildfire measures are implemented.

Wedge Stirrup
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 58 of 59
58 Avista 2023 Wildfire Resiliency Plan
Wildland Urban Interface: Or WUI, is the zone of transition between wilderness (unoccupied land) and
land developed by human activity; basically, where the natural environment (typically forested areas)
meets the built environment. Homes and businesses located in WUI zones are most at-risk from the
impact of wildfires, as they are often located in rural areas lacking adequate fire suppression
resources. The WUI map helps to identify and prioritize these areas of greatest risk and serves to
inform the recommendations and operational decisions related to wildfire
resiliency. Using this map, programs can be targeted where they have the
potential to reduce the most risk and have the greatest positive impact in
the safety and protection of customers and infrastructure.

Wire Down: Instance where an electric transmission or distribution conductor
is broken and falls from its intended position to rest on the ground or a
foreign object. If the conductor contacts dry materials on the ground and is
live, the sparks created can lead to a fire.

Wood Pole Wraps: Avista uses Genics Fire Mesh, a wire mesh treated with
an intumescent material that, when exposed to extreme heat, rapidly
expands to form a barrier between the fire and the wood pole. These wraps
help prevent low-burning fires from accessing wood poles, protecting them
from damage or destruction.

Fire Mesh Wood
Pole Wrap
Exhibit No. 10 Case No. AVU-E-23-01 D. Howell, Avista
Schedule 1, Page 59 of 59