Unit 4 Damage-Frequency Assessmentflghc.org/ppt/2014/Training Sessions/TS20 Benefit List...
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Unit 4. Damage Frequency Assessment 4-1-1
Unit 4
Damage-Frequency
Assessment
Unit 4. Damage Frequency Assessment -24-2
Unit 4 Objectives
Identify when to use the DFA module
List the hazards when the DFA
module can be used
Identify the sources of documentation
necessary to successfully complete a
DFA BCA
Accurately complete a DFA BCA
using a pre-defined case study
Unit 4. Damage Frequency Assessment 4-3
When to use the DFA Module
When any of the following situations apply:
Mitigating risk to non-buildings:
Utilities
Roads
Infrastructure
Mitigating risk to buildings, but structure or hazard data are unavailable
Unit 4. Damage Frequency Assessment 4-4
DFA Module Overview
The Flood Module runs on data and probabilities; for the
DFA Module, users provide all of the data needed to
calculate the BCA
Like it sounds, the user-input data is attaching damage
values to the frequency (recurrence intervals) of actual
historic events
Users must provide post-project effectiveness values; this
is done for you in the Flood Module
The Tool calculates before-project damages and
subtracts the after-project damages
Unit 4. Damage Frequency Assessment 4-5
DFA Module Overview (cont.)
Requires some assumptions and sound engineering
judgment, especially for after-project effectiveness
DFA provides flexibility and can be used for a wide range
of hazards and project types
If recurrence intervals from historic events are unknown,
the Tool can calculate recurrence intervals for you
Unit 4. Damage Frequency Assessment 4-6
DFA Hazard Types
The DFA module can
be used for a variety of
hazards including:
Snow/ice storm
Earthquake
Tsunami
Unit 4. Damage Frequency Assessment 4-7-7
Landslides and Mudflows
Landslides and mudflows are
different from other hazards
because there is seldom data for
recurrence
Typically requires acquisition,
relocation, or stabilization of
buildings, roads, and other
facilities
Unit 4. Damage Frequency Assessment 4-8
Landslides and Mudflows (cont.)
Methodologies:
Slope failure is imminent
Projects with an annual rate of erosion
Contact the BCA Helpline for guidance on how to calculate
Unit 4. Damage Frequency Assessment 4-9
DFA Requirements
1. Typical analyses use documented historical damages/losses from two or more hazard events of known frequencies from:
FEMA Project Worksheets/Damage Survey Reports,
Insurance or repair records, or
Newspaper articles citing other credible sources
2. Typical analyses use documented frequencies associated with each hazard event based on:
Comparison of observed flood elevations or discharges to FIS,
stream gauge or tide gauge data
Documented data from a credible source to estimate
frequencies
The unknown frequency calculator with supporting
documentation when the requirements are met
Unit 4. Damage Frequency Assessment 4-10
DFA Key Data Inputs and BCA Documentation
Unit 4. Damage Frequency Assessment 4-11
DFA Documentation
The DFA Module requires documentation of the following key
data:
Value of Services (Roads/Utilities)
Loss of Service Durations
Historical Damages
Loss Event Frequencies
Residual Damages/Losses (Project Effectiveness)
Other documentation
Unit 4. Damage Frequency Assessment 4-12
Value of Services (Roads)
The number of one-way trips, and additional detour time and
mileage to calculate an economic benefit.
Documentation:
Traffic counts from a reliable source
Detour time estimates and distance with maps
Other sources – For smaller subdivision roads where
traffic counts are unavailable, one-way trips may be
estimated using the TRB Highway Capacity Manual or
other recognized sources
Unit 4. Damage Frequency Assessment 4-13
Roads/Bridges - Examples
Unit 4. Damage Frequency Assessment 4-14
Value of Services (Utilities)
The number of people impacted by the loss of service is multiplied by a FEMA
standard economic value for the service, then multiplied by the number of days
of service loss
Recommended documentation:
Projects that prevent loss of service to the entire community can use
the current community population
Projects that benefit a portion of a community or people outside a
community need documentation from the utility showing the number
of accounts. An adjustment to determine the number of people may
be needed.
FEMA Project Worksheets
News article that links the event to the outage duration
Unit 4. Damage Frequency Assessment 4-15
Value of Services (Public Buildings)
The annual budget for a public facility like a hospital, school, or
government building is used to calculate an economic value based on
the duration (in days) of service loss
Recommended documentation:
Copy of the annual budget for the actual facility being
mitigated
This could be multiple departments in one building or one
building our of a larger entity like a school district
Letter from someone competent to provide the annual budget
value
Unit 4. Damage Frequency Assessment 4-16
Historical Event Damages/Losses
Recommended documentation:
FEMA Project Worksheets/Damage Survey Reports
Insurance claims, BureauNet, damage repair records, or data
from the State/local agency, local government
Newspaper accounts citing credible sources (other than
homeowner accounts)
High water marks tied to depth-damage function damages
Other documentation
Unit 4. Damage Frequency Assessment 4-17
Historical Event Frequencies
Recommended documentation:
Frequencies linked to documented FIS data
U.S. Geological Society (USGS) stream gauge data or
National Oceanic and Atmospheric Administration (NOAA) tide
gauge data
Copies of engineering/technical expert reports
Use the unknown frequency calculator with supporting
documentation when requirements are met
Unit 4. Damage Frequency Assessment 4-18
Analysis Period
The “window of time” through which the frequency of
damaging events are seen in DFA
Most often based on the date of construction
Must be a minimum of 10 years
Can be adjusted with appropriate documentation for
reasons like altered hydrology, complete reconstruction, or
a 50-year analysis duration is acceptable if the date of
construction is unknown for roads and rural electric lines
Unit 4. Damage Frequency Assessment 4-19
Analysis Period Documentation
Documentation must come
from a competent source:
Floodplain map change correspondence
Rapid development photographs
Engineering reports
Other sources
BEFORE
AFTER
Unit 4. Damage Frequency Assessment 4-20
Unknown Frequency Calculator: Requirements
The unknown frequency calculator can only be used when the following requirements are met:
1. Minimum of three hazard events occurring in different years where either:
The frequencies/RIs of all events are unknown, or
The frequencies/RIs of up to two events are known and have total inflated values that exceed the total inflated values of all the other unknown frequency/RI events
2. Period of record based on the age of the structure or a minimum of 10 years; whichever is greater
3. No other way to tie historical events to known frequencies/RIs
Unit 4. Damage Frequency Assessment 4-21
Unknown Frequency Calculator: Documentation
Recommended documentation:
Three historical events of unknown frequency
Date of construction (needed for the period of record)
Sources of documentation may include:
Insurance claims, damage repair records, technical reports,
data from the State/local agency, local government, etc.
Extraordinary claims require extraordinary documentation!
Unit 4. Damage Frequency Assessment 4-22
Project Effectiveness
Elements to documenting project effectiveness:
Keep in mind that nearly all mitigation projects have some
residual risk/damages
Some projects will not completely eliminate damages after
mitigation, but will reduce damages by a certain percentage
Consult with the mitigation project designer to determine the
level of effectiveness
Assume damages after mitigation occur once the level of
effectiveness frequency is reached
Unit 4. Damage Frequency Assessment 4-23
Summary: Documenting DFA Data
Methods to derive data from documented events:
Interpolation between known data points (but not by extrapolating above or below known data points)
Calculate estimates based on “typical values” such as:
Examples of good and bad documentation for each of the key DFA inputs are provided on the slides that follow.
FEMA Depth-Damage functions for buildings,
contents, and displacement costs
Damage functions or relationships from other credible
sources
Unit 4. Damage Frequency Assessment 4-24
DFA Documentation: Value of Services (Roads/Utilities)
Acceptable Documentation
DOT traffic counts and detour
time estimates with maps
(roads)
Local utility company data
indicating number of
impacted accounts (utilities)
Unacceptable Documentation
“Ballpark” estimates of traffic
counts/detour times without
maps (roads)
Population/census data not
correlated to utility service area
(utilities)
For FEMA standard values for services, refer to FEMA’s
BCA Toolkit
Unit 4. Damage Frequency Assessment 4-25
DFA Documentation: Historical Damage Event Costs/Losses
Acceptable Documentation
FEMA Project
Worksheets/DSRs
Insurance or damage repair
records from DOT, DPW, utility
company
Damages estimated based on
FEMA standard values
Unacceptable Documentation
Extrapolated damages or
service losses
Road and utility maintenance
costs not tied to damage events
Newspaper articles that do not
cite credible sources (i.e., other
than homeowner accounts)
Unit 4. Damage Frequency Assessment 4-26
DFA Documentation: Historical Damage Event Frequencies
Acceptable Documentation
Frequencies linked to
documented FIS data
USGS stream gauge data or
NOAA data
Copies of engineering/
technical expert reports
Using the unknown frequency
calculator with supporting
documentation
Unacceptable Documentation
Assuming all recurring damages
occur at the 1-year frequency
Extrapolated event frequencies
Using the unknown frequency
calculator with no explanation or
supporting documentation
Unit 4. Damage Frequency Assessment 4-27
DFA Documentation: After-Mitigation Damages/Losses
Acceptable Documentation
Engineering or technical
report
A detailed project scope that
clearly indicates the level of
effectiveness
Plans or specifications
Unacceptable Documentation
Assuming no damages occur
after mitigation for non-
acquisition projects
Poorly-defined project scopes
with no clear level of
effectiveness
Remember most mitigation projects do not eliminate
all future damages (except acquisition)
Unit 4. Damage Frequency Assessment 4-28
BCA Software
Case Study 1
Unit 4. Damage Frequency Assessment 4-29
Add a new
structure
Select the
State and
county from
the drop-
down menu
Overview of DFA BCA Tool
Unit 4. Damage Frequency Assessment 4-30
Add a new
project
Organization
is
subapplicant
POC is the
person who
can answer
questions
about the
project
Overview of DFA BCA Tool
Unit 4. Damage Frequency Assessment 4-31
Add the
structure to
the project
Overview of DFA BCA Tool
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Select
Damage
Frequency
Assessment
to begin the
mitigation
project
analysis
Overview of DFA BCA Tool
Unit 4. Damage Frequency Assessment 4-33
Overview of DFA BCA Tool
Select from
multiple
hazard
types for
proposed
project
Enter
damage
information
Unit 4. Damage Frequency Assessment 4-34
Overview of DFA BCA Tool
Enter the
project useful
life
Select Yes for:
Do you have a
detailed Scope
of Work?
Easy-to-use
cost estimation
framework
provided
Unit 4. Damage Frequency Assessment 4-35
Overview of DFA Tool
What forms of documentation
would you provide in this
area of the module?
Unit 4. Damage Frequency Assessment 4-36
Overview of DFA BCA Tool
Select loss
of function
type
Software
auto-
populates
total value
of the
service per
day
Unit 4. Damage Frequency Assessment 4-37
Overview of DFA BCA Tool
Select type
of service
Enter utility
data
Unit 4. Damage Frequency Assessment 4-38
Overview of DFA BCA Tool
Input data for:
Year built
Updated FEMA
BCA inflation
calculator
incorporated
Can add or
delete columns
for specific
damages
Unit 4. Damage Frequency Assessment 4-39
Overview of DFA BCA Tool
Damages after
mitigation auto-
populated
Input data for:
Return
Interval
Downtime
(days)
Can attach
documentation
directly into the
software
Unit 4. Damage Frequency Assessment 4-40
Overview of DFA BCA Tool
Summary of
benefits and
costs
BCR value
Select Save
and Go Back to
change values
used in the
analysis
Unit 4. Damage Frequency Assessment 4-41
Check on Learning Activity& Case Study
Purpose of Activities
To review the DFA topics covered in
this unit.
Unit 4. Damage Frequency Assessment 4-42
Conclusion
FEMA Damage-Frequency Assessment
Remember: It is always about risk, regardless of the hazard
Good mitigation projects address high- risk situations
Poor mitigation projects address low- risk situations