section 4.4 - hazard vulnerability summary · westmoreland county hazard mitigation plan 4.4-2...

SECTION 4.4: HAZARD VULNERABILITY SUMMARY

Westmoreland County Hazard Mitigation Plan 4.4-1

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4.4 HAZARD VULNERABILITY SUMMARY

A risk assessment is the process of measuring the potential loss of life, personal injury, and economic and

property damage that may affect a community resulting from identified hazards. It allows planning personnel

to address and reduce hazard impacts, and emergency management personnel to establish early response

priorities by identifying potential hazards and vulnerable assets. Results of the risk assessment are used in

subsequent mitigation planning processes, including determining and prioritizing mitigation actions that reduce

each jurisdiction’s risk to a specified hazard.

This section describes the vulnerability assessment process for the Westmoreland County Hazard Mitigation

Plan (HMP). Past, present, and future conditions must be evaluated to most accurately assess risk for the

County and each jurisdiction.

4.4.1 Risk Assessment Methodology

Asset Inventories

Population

As discussed in Section 2 (County Profile) research has shown that some populations are at greater risk from

hazard events because of decreased resources or physical abilities. For the purposes of this planning process,

vulnerable populations in Westmoreland County include children, elderly people, low-income populations,

people with physical or mental disabilities, and non-English speakers.

The 2010 U.S. Census block data layers were used to estimate exposure and potential impacts to the general

population. The 2010 U.S. Census demographic data available in Federal Emergency Management Agency’s

(FEMA) Hazards U.S.—Multi-Hazard (HAZUS-MH) v4.2 model was used to estimate potential impacts to the

elderly (over 65 years of age) and populations with income below the poverty threshold.

The census blocks do not follow the boundaries of the hazard areas, possibly leading to gross overestimates or

underestimates of exposed populations from use of centroids or intersects of census blocks with these zones.

Limitations of these analyses are recognized, and thus the results are used only to provide a general estimate.

For Section 4.3.5 (Flood, Flash Flood, and Ice Jam), the FEMA Digital Flood Insurance Rate Maps (DFIRM)

were overlaid upon residential buildings from the general building stock inventory to provide a more accurate

exposure estimate. The number of structures located in the hazard areas was totaled and multiplied by the

average household size for Westmoreland County – 2.32 (U.S. Census 2010). Limitations of these analyses

are recognized, and thus results are used only to provide a general estimate for planning purposes.

Buildings

The building footprint spatial layer provided by the Westmoreland County Geographic Information System

(GIS) department and the default general building stock data in HAZUS-MH based on the 2010 U.S. Census

and 2016 RSMeans cost data, were used to assess exposure and estimate potential losses to flood and wind

events at the municipal level. As noted above, U.S. Census blocks do not follow hazard boundaries, possibly

leading to gross overestimates or underestimates of exposed building stock value. Limitations of these

analyses are recognized, and thus the results are used only to provide a general estimate.



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Critical Facilities

The critical facility inventory, which includes essential facilities, utilities, transportation features and user-

defined facilities as outlined in Section 2 (County Profile), was updated beginning with all GIS data provided

by the Westmoreland County GIS Department. To protect individual privacy and the security of assets, asset

information is presented in some cases in aggregate, without details about specific individual properties or

facilities.

New Development

In addition to summarizing the current vulnerability, Westmoreland County examined recent and anticipated

new development that can affect the County’s vulnerability to hazards. Identifying these changes and

integrating into the risk assessment ensures they are considered when developing the mitigation strategy to

reduce these vulnerabilities in the future. An exposure analysis was conducted using anticipated and recent

new development provided by each jurisdiction.

Methodology

To address the requirements of the Disaster Mitigation Act of 2000 (DMA 2000) and better understand

potential vulnerability and losses associated with hazards of concern, Westmoreland County used standardized

tools—combined with local, state, and federal data and expertise—to conduct the risk assessment. Three

different levels of analysis were used depending upon the data available for each hazard as described below:

1. Historic Occurrences and Qualitative Analysis – This analysis includes an examination of historic

impacts to understand potential impacts of future events of similar size. In addition, potential impacts

and losses are discussed qualitatively using best-available data and professional judgment.

2. Exposure Assessment – This analysis involves overlaying available spatial hazard layers, or hazards

with defined extent and locations, with assets in GIS to determine which assets are located in the

impact area of the hazard. The analysis highlights which assets may be affected by the hazard. If the

center of each asset is located in the hazard area, it is deemed exposed and potentially vulnerable to

the hazard.

3. Loss estimation — The FEMA HAZUS-MH modeling software was used to estimate potential losses

for the following hazards: flood, earthquake, severe storm (wind). In addition, an examination of

historic impacts and an exposure assessment was conducted for these spatially-delineated hazards.

Hazards U.S. – Multi-Hazard (HAZUS-MH)

In 1997, FEMA developed a standardized model for estimating losses caused by earthquakes, known as

Hazards U.S. or HAZUS. HAZUS was developed in response to the need for more effective national-, state-,

and community-level planning and the need to identify areas that face the highest risk and potential for loss.

HAZUS was expanded into a multi-hazard methodology, HAZUS-MH, with new models for estimating

potential losses from wind (hurricanes) and flood (riverine and coastal) hazards. HAZUS-MH is a GIS-based

software tool that applies engineering and scientific risk calculations that have been developed by hazard and

information technology experts to provide defensible damage and loss estimates. These methodologies are

accepted by FEMA and provide a consistent framework for assessing risk across a variety of hazards. The GIS

framework also supports the evaluation of hazards and assessment of inventory and loss estimates for these

hazards.

HAZUS-MH uses GIS technology to produce detailed maps and analytical reports that estimate a community’s

direct physical damage to building stock, critical facilities, transportation systems and utility systems. To

generate this information, HAZUS-MH uses default data for inventory, vulnerability, and hazards; the default



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data can be supplemented with local data to provide a more refined analysis. Damage reports can include

induced damage (inundation, fire, threats posed by hazardous materials and debris) and direct economic and

social losses (casualties, shelter requirements, and economic impact) depending on the hazard and available

local data. HAZUS-MH’s open data architecture can be used to manage community GIS data in a central

location. The use of this software also promotes consistency of data output now and in the future and

standardization of data collection and storage. The guidance, Using HAZUS-MH for Risk Assessment: How-to

Guide (FEMA 433) was relied upon to support the application of HAZUS-MH for this risk assessment and

plan (FEMA 2015). More information on HAZUS-MH is available at https://www.fema.gov/hazus.

HAZUS provides default data for inventory, vulnerability, and hazards; the default data can be supplemented

with local data to provide a more refined analysis. The model can carry out three levels of analysis, depending

on the format and level of detail of information about the planning area:

▪ Level 1—All of the information needed to produce an estimate of losses is included in the software’s

default data. This data is derived from national databases and describe in general terms the characteristic

parameters of the planning area.

▪ Level 2—More accurate estimates of losses require more detailed information about the planning area. To

produce Level 2 estimates of losses, detailed information is required about local geology, hydrology,

hydraulics, and building inventory, as well as data about utilities and critical facilities. This information is

needed in a GIS format.

▪ Level 3—This level of analysis generates the most accurate estimate of losses. It requires detailed

engineering and geotechnical information to customize it for the planning area.

HAZUS-MH uses two types of Census block-based data: homogenous and dasymetric. Homogenous blocks

display the full extent of each block, while the dasymetric census blocks have had homogenous undeveloped

areas (bodies of water, forests, etc.) removed. The dasymetric blocks were developed to provide more accurate

loss estimates by excluding uninhabited and undeveloped areas of a Census block. To estimate the

replacement cost value of structures located within the hazard areas, the default dasymetric Census block

general building stock data in HAZUS-MH v4.2 was used.

In general, probabilistic analyses are performed to develop estimates of long-term average losses (annualized

losses), as well as an expected/estimated distribution of losses (mean return period losses) for the flood and

hurricane/wind hazards. The probabilistic hazard analysis generates estimates of damage and loss for specified

return periods. For annualized losses, HAZUS-MH v4.2 calculates the maximum potential annual dollar loss

resulting from various return periods averaged on a "per year" basis. It is the summation of all HAZUS-

supplied return periods (e.g., 10, 50, 100, 200, 500) multiplied by the return period probability (as a weighted

calculation). In summary, the estimated cost of a hazard (earthquake and wind) each year is calculated.

Avalanche

A qualitative analysis was conducted for the avalanche hazard based on best-available data and professional

judgment.

Drought

To assess the vulnerability to drought and its associated impacts, a qualitative assessment was conducted. The

U.S. Department of Agriculture (USDA) Census of Agriculture 2017 (USDA 2018) was used to estimate

economic impacts to the County. Information regarding the exposed farmland areas and total market value of

https://www.fema.gov/hazus



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livestock and poultry and other agricultural products sold, etc. was extracted from the report and summarized

in the vulnerability assessment.

Earthquake

A probabilistic assessment was conducted for the 500-year mean return period (MRP) event through a Level 2

analysis in HAZUS-MH v4.2 to analyze the earthquake hazard and provide a range of loss estimates. Overall,

the three asset inventories (population, building stock, critical facilities) in Westmoreland County are

considered exposed and vulnerable to the earthquake hazard. Additionally, potential building damage was

evaluated by HAZUS-MH v4.2 across the following damage categories: none, slight, moderate, extensive, and

complete.

Extreme Temperature

A qualitative analysis was conducted for the radon hazard based on best-available data and professional

judgment.

Flood, Flash Flood, and Ice Jam

The 1-percent and 0.2-percent annual chance flood events were examined to evaluate Westmoreland County’s

risk to the riverine flood hazard. These flood events are generally those considered by planners and evaluated

under federal programs such as the National Flood Insurance Program (NFIP). Generally, Westmoreland

County’s effective map date is March 17, 2011, though one panel is effective as of September 26, 2014.

FEMA Risk Map products dated March 2011 from the Flood Risk Database (FRD) were considered best-

available data for Westmoreland County at the time the 2020 HMP was drafted. The 2011 Risk Map 1- and

0.2-percent annual chance floodplains were used to estimate exposure. The 1-percent annual chance flood

depth grid available from Risk Map was integrated into the HAZUS-MH 4.2 riverine flood model to estimate

potential losses in the County. The following is an excerpt from FEMA’s 2018 “Guidance for Flood Risk

Analysis and Mapping” describing this data:

In many cases, the core spatial data compiled for the FRD [Flood Risk Database] is derived

from other FEMA datasets (e.g., the S_CSLF_Ar feature class is derived from the

S_Fld_Haz_Ar feature class from the National Flood Hazard Layer (NFHL) and new Flood

Insurance Rate Map (FIRM) databases. These FEMA datasets should have been compiled to

FEMA specifications as described in the FIRM Database Technical Reference and other

FIRM Database Guidance. In this regard, the flood risk datasets should inherit much of the

quality and integrity with which their parent datasets were created (FEMA 2018).

To estimate exposure to the 1- and 0.2-percent annual chance flood events, the 2011 Risk Map flood

boundaries, default general building stock data in HAZUS-MH 4.2, Westmoreland County building footprint

layer, updated critical facility inventories and 2010 U.S. Census population data were used; assets with their

centroid located in the hazard areas were totaled to estimate exposure. The HAZUS-MH 4.2 riverine flood

model was run to estimate potential losses for Westmoreland County for the 1-percent annual chance flood

event. HAZUS-MH 4.2 calculated the estimated potential losses to the population (default 2010 U.S. Census

data) and potential damages to the updated general building stock and critical facility inventories based on the

depth grid generated and the default HAZUS damage functions in the flood model.

To estimate debris generated by the 1-percent annual chance flood event, HAZUS-MH v4.2, which was

released on January 29, 2018, was used instead of HAZUS-MH v4.0. This is because a FEMA-known error in

v4.0 was detected, and the issue appears to have been resolved with the latest software release.



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Hailstorm

A qualitative analysis was conducted for the hailstorm hazard based on best-available data and professional

judgment.

Hurricane and Tropical Storm

A HAZUS-MH 4.2 probabilistic analysis was performed to analyze the wind hazard. The probabilistic

hurricane model activates a database of thousands of potential storms that have tracks and intensities reflecting

the full spectrum of Atlantic hurricanes observed since 1886 and identifies those with tracks associated with

Westmoreland County. HAZUS-MH also includes surface roughness and vegetation (tree coverage) maps for

the area. Surface roughness and vegetation data support the modeling of wind force across various types of

land surfaces. Annualized losses and the 100- and 500-year MRPs were examined for the wind/severe storm

hazard. Default demographic and updated building and critical facility inventories in HAZUS-MH 4.2 were

used for the analysis.

There is currently a FEMA-acknowledged issue with importing user-defined facilities in HAZUS-MH versions

4.0 and 4.2, available at the time of the 2019 HMP update. To estimate potential losses to user-defined

facilities identified by Westmoreland County, they were appended to the Emergency Operation Centers input

in HAZUS-MH Comprehensive Data Management System (CDMS) and uploaded to the program.

Landslide

To estimate exposure to landslide, a U.S. Geological Survey (USGS) landslide hazard area was overlaid upon

the asset data (population, buildings, critical facilities). County assets with their center located in the hazard

area are reported as exposed and potentially vulnerable to landslide events.

Lightning

A qualitative analysis was conducted for the lightning hazard based on best-available data and professional

judgment.

Radon Exposure


judgment.

Subsidence and Sinkholes

There is no standard loss estimation model available for the mine subsidence hazard. To determine the assets

that are exposed to this hazard, available and appropriate spatial data delineating the extent of Pennsylvanian

rock and anthracite fields (generated by the Pennsylvania Bureau of Topographic and Geologic Survey in

2015) were overlaid upon the asset data (population, buildings, critical facilities). The assets with their center

located in the hazard area are reported as exposed and potentially vulnerable to mine subsidence events. The

U.S. Census blocks do not align with the anthracite field polygon in the spatial data; therefore, these estimates

are for planning purposes only. The limitations of this analysis are recognized and are only used to provide a

general estimate of exposure.

Tornadoes and Windstorms

To assess the tornado hazard, the number of manufactured homes was totaled per each municipality to provide

an estimate of the vulnerability from a tornado event. The structure totals were pulled from tax assessment



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data by the Westmoreland County Planning Division. The following three categories were used to calculate

the number of manufactured homes per municipality:

▪ RT = a trailer where the trailer owner and landowner are the same, but the land is less than 10 acres.

▪ AT = a trailer where the trailer owner and landowner are the same, but the land is greater than 10 acres.

▪ T= a trailer where the trailer owner and the landowner are not the same and the land is typically leased.

Wildfire

The wildfire urban interface (WUI)—obtained through the SILVIS Lab, Department of Forest Ecology and

Management, University of Wisconsin-Madison—was used to define the wildfire hazard areas. The

University of Wisconsin-Madison wildland fire hazard areas are based on the 2010 U.S. Census and 2006

National Land Cover Dataset and the Protected Areas Database. For the purposes of this risk assessment, the

high, medium, and low-density interface areas were combined and used as the “interface” hazard area and the

high, medium, and low-density intermix areas were combined and used as the “intermix” hazard areas. The

defined hazard area was overlaid upon the asset data (population, building stock, critical facilities) to estimate

the exposure to the wildfire hazard.

Winter Storm

The entire general building stock inventory in Westmoreland County is exposed and vulnerable to the winter

storm hazard. In general, structural impacts include damage to roofs and building frames, rather than building

content. Current modeling tools are not available to estimate specific losses for the winter storm hazard.

Historic data on structural losses to general building stock are not adequate to predict specific losses to this

inventory; therefore, a percentage of the HAZUS-MH v4.2 default general building stock structural

replacement cost value was used to estimate damages that could result from winter storm conditions. This

methodology is based on FEMA’s How-to Series (FEMA 386-2), Understanding Your Risks, Identifying and

Estimating Losses (FEMA 2001) and FEMA’s Using HAZUS-MH for Risk Assessment (FEMA 433) (FEMA

2004). Given professional knowledge and the currently available information, the potential losses for this

hazard are considered to be overestimated; hence, providing a conservative estimate for losses associated with

winter storm events.

Dam Failure

Digital dam failure inundation area maps were not available for inclusion in the risk assessment. A qualitative

analysis was conducted for the dam failure hazard based on best-available data and professional judgment.

Environmental Hazards

The Federal Title III Superfund Amendments and Reauthorization Act (SARA), the Emergency Planning and

Community Right to Know Act, and the Commonwealth of Pennsylvania set up requirements for producing,

storing, and transporting hazardous materials. These hazardous materials may be released either at their

storage facility location (fixed site) or in-transit.

The Pennsylvania Department of Transportation State Roads layer (2011) was used to define the hazard area

around major roadways. The hazard area was defined as a 0.25-mile buffer around the Interstate, State, and

U.S. roadways where hazardous materials may be in transit to estimate areas that may be directly or indirectly

impacted by a release. The County provided a rail line spatial layer and a spatial layer for national pipelines

was sourced from the Homeland Security Infrastructure Program (HSIP). Like with the major roadways, the

hazard area was defined as a 0.25-mile buffer around these features as well. Additionally, the identified



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primary vulnerability radii around the SARA Title III facilities from the County spatial layer was used to

estimate potential exposure.

The defined hazard areas were overlaid upon the asset data (population, building stock, critical facilities) to

estimate the exposure to each hazard.

Illicit Drug Use


judgment.

Nuclear Incident

Westmoreland County is located within the Ingestion Exposure Pathway Emergency Planning Zones (EPZ) of

the Beaver Valley Power Station located in Beaver County, PA. The 50-mile EPZ was used to define the

hazard area for a nuclear incident. The defined hazard area was overlaid upon the asset data (population,

building and critical facilities) to estimate exposure to the nuclear incident hazard.

Structural Fire

A qualitative analysis was conducted for the structural fire hazard based on best-available data and

professional judgment.

Terrorism

A qualitative analysis was conducted for the terrorism hazard based on best-available data and professional

judgment.

Transportation Accident

A qualitative analysis was conducted for the transportation accident hazard based on best-available data and


Utility Failure

A qualitative analysis was conducted for the utility interruption hazard based on best-available data and


Limitations

For this risk assessment, the loss estimates, exposure assessments, and hazard-specific vulnerability

evaluations rely on the best-available data and methodologies. Uncertainties are inherent in any loss

estimation methodology and arise in part from incomplete scientific knowledge concerning natural hazards and

their effects on the built environment. Uncertainties also result from the following:

1. Approximations and simplifications necessary to conduct such a study

2. Incomplete or dated inventory, demographic, or economic parameter data

3. The unique nature, geographic extent, and severity of each hazard

4. Mitigation measures already employed by the participating municipalities

5. The amount of notice residents have in advance to prepare for a specific hazard event

These factors can result in a range of uncertainty in loss estimates, possibly by a factor of two or more.

Therefore, potential exposure and loss estimates are approximate. These results do not predict precise results



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and should be used to understand relative risk. Over the long term, Westmoreland County will collect

additional data to assist in developing refined estimates of vulnerabilities to natural and non-natural hazards.

Potential economic loss is based on the present value of the general building stock utilizing best-available data.

The County acknowledges significant impacts may occur to critical facilities and infrastructure as a result of

these hazard events causing great economic loss. However, monetized damage estimates to critical facilities

and infrastructure, and economic impacts were not quantified and require more detailed loss analyses. In

addition, economic impacts to industry such as tourism and the real-estate market were not analyzed.

4.4.2 Ranking Results

As discussed in Section 4.2 (Hazard Identification), a comprehensive range of natural and non-natural hazards

that pose significant risk to Westmoreland County were selected and considered in this plan. However, the

communities in Westmoreland County have differing levels of exposure and vulnerability to each of these

hazards. It is important for each community participating in this plan to recognize those hazards that pose the

greatest risk to their community and direct their attention and resources accordingly to most effectively and

efficiently manage risk.

To this end, a relative hazard risk ranking process was conducted for the County using the Risk Factor (RF)

methodology identified in Section 5 and Appendix 9 of Pennsylvania Emergency Management Agency’s

(PEMA) All-Hazard Planning Standard Operating Guide (PEMA 2013). The guidance states:

The RF approach produces numerical values that allow identified hazards to be ranked against one

another (the higher the RF value, the greater the hazard risk). RF values are obtained by assigning

varying degrees of risk to five categories for each hazard: probability, impact, spatial extent, warning

time, and duration.

To calculate the RF value for a given hazard, the assigned risk value for each category is multiplied by

the weighting factor. The sum of all five categories equals the final RF value, as demonstrated in the

example equation below:

Hazards identified as high risk have RFs greater than or equal to 2.5. RFs ranging from 2.0 to 2.4 are

considered moderate-risk hazards. Hazards with RFs less than 2.0 are considered low risk.

Table 4.4-1 summarizes the five risk assessment categories, the criteria and associated risk level indices used

to quantify their risk, and the suggested weighting factor (weight value) applied to each risk assessment

category. Table 4.4-2 shows the five risk assessment categories’ values for each of Westmoreland County’s

hazards and each hazard’s RF.



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Table 4.4-1. Summary of Risk Factor (RF) Approach

Source: PEMA 2013



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Table 4.4-2. Risk Ranking for Westmoreland County

HAZARD

RISK HAZARDS

RISK ASSESSMENT CATEGORY RISK

FACTOR

(RF) PROBABILITY IMPACT SPATIAL

EXTENT

WARNING

TIME DURATION

HIG

H

Flood, Flash

Flood, and Ice

Jam

4 4 2 1 3 3.2

Illicit Drug Use 4 4 1 4 1 3.1

Utility

Interruptions 4 1 4 4 3 3

Winter Storm 4 2 4 1 3 3

Tornado,

Windstorm 4 3 2 4 1 3

Environmental

Hazards 4 3 1 4 2 2.9

Terrorism 4 3 1 4 1 2.8

Extreme

Temperatures 4 1 4 1 3 2.7

Radon

Exposure 4 1 3 1 4 2.6

Hailstorm 4 1 4 1 1 2.5

Landslide 3 3 1 4 1 2.5

MO

DE

RA

TE

Wildfire 4 1 1 4 2 2.3

Drought 2 1 4 1 4 2.2

Structural Fire 4 1 1 4 1 2.2

Transportation

Accidents 4 1 1 4 1 2.2

Hurricane and

Tropical Storm 2 1 4 1 3 2.1

LO

W

Earthquake 1 1 4 4 1 1.9

Nuclear

Incidents 1 1 4 3 2 1.9

Subsidence and

Sinkholes 3 1 1 4 1 1.9

Lightning 2 1 1 2 1 1.4

Dam Failure 1 1 1 3 2 1.3

Avalanche 1 1 1 1 1 1

Based on these results, there are 1 high-risk hazards, 5 moderate-risk hazards, and 6 low-risk hazards in

Westmoreland County. Mitigation actions were developed for all high-risk, moderate-risk, and low-risk

hazards (further discussed in Section 6.4). The threat posed to life and property for moderate-risk and high-

risk hazards is considered significant enough to warrant the need for establishing hazard-specific mitigation

actions. Mitigation actions related to future public outreach and emergency service activities are identified to

address low-risk hazard incidents.

A risk assessment result for the entire County does not mean that each municipality is at the same amount of

risk to each hazard. Table 4.4-3 shows the different municipalities in Westmoreland County and whether their

risk is greater than (>), less than (<), or equal to (=) the RF assigned to the County as a whole.



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Table 4.4-3. Jurisdictional Risk by Municipality

Municipality

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1.0 1.3 2.2 1. 9 2.9 2.7 3.2 2.5 2.1 3.1 2.5 1.4 1.9 2.6 2.2 1.9 2.8 3.0 2.2 3.0 2.3 3.0

Adamsburg Borough < < < = > = = = = = = = > = > > = < > = > =

Allegheny Township = > = = = = = = = = = = > = = < = = = = > =

Arnold, City of < < < = > = = = = = < = > = > < = < > = > =

Arona Borough < < < = > > > = = > > = > = > < < < > = > =

Avonmore Borough < < < = > = = = = = < = = = > < = < > = > =

Bell Township = > = = > = = = = = = = > = = < = = = = > =

Bolivar Borough < < < = > = > = = = = = = = > < = < > = > =

Cook Township = < = = < = > > = = = = < = = < < = = = > =

Delmont Borough < < < = > = = = = = = = > = > = = < > = > =

Derry Borough < < < = > = > = = = < = = = > < = < > = > =

Derry Township = > = = > = > = = = = = = = = = = = = = > =

Donegal Borough < < < = > = = = = = = = = = > < = < > = > =

Donegal Township = > = = = = = = = = = = = = = < = = = = > =

East Huntingdon

Township = < = = = = = = = = < = = = = = = = = = < =

East Vandergrift Borough < < < = > = = = = = < = > = > < = < > = > =

Export Borough < < < = > = > = = = = = > = > = = < > = > =

Fairfield Township = > = = = = = = = = > = = = = < = = = = > =

Greensburg, City of < < < = > = = = = = > = = = > > > < > = < =

Hempfield Township = > = = = = = = = = = = > = = = = = = = < =



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Municipality

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1.0 1.3 2.2 1. 9 2.9 2.7 3.2 2.5 2.1 3.1 2.5 1.4 1.9 2.6 2.2 1.9 2.8 3.0 2.2 3.0 2.3 3.0

Hunker Borough < < < = > = = = = = > = = = > < = < > = < =

Hyde Park Borough < < < = > = = = = = < = > = > > = < > = > =

Irwin Borough < < < = > = = = = = = = > = > > = < > = < =

Jeannette, City of < > < = = = = = = > = = > = > < = < > > < =

Latrobe, City of < < < = > = > = = = < = = = > > = < > = < =

Laurel Mountain Borough < < < = > = = = = = < = = = > < = < > = > =

Ligonier Borough < = < = > = > = = = < = = = > < = < > = > =

Ligonier Township = > = = = = > = = = > = < > = < < = = > > =

Lower Burrell, City of < < < = > = = = = = < = > = > < = < > = < =

Loyalhanna Township = < = = > = = = = = = = > = = < = = = = > =

Madison Borough < < < = > = = = = = > = > = > = = < > = < =

Manor Borough < < < = = = > = = = > = > = > > = < > = < =

Monessen, City of < < < = = = = = = = > = > = > > = < > = < =

Mount Pleasant Borough < < < = > = = = = = > = = = > > = < > = < =

Mount Pleasant Township = > = = = = = = = = = = = = = > = = = = < =

Murrysville, Municipality

of < < < = = = = = = = = = > = > < = < > = > =

New Alexandria Borough < < < = > = > = = = = = = = > < = < > = > =

New Florence Borough < < < = > = > = = = < = = = > < = < > = > =

New Kensington, City of < < < = > = = = = = < = > = > < = < > = > =

New Stanton Borough < < < = > = = = = = < = = = > < = < > = < =



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North Belle Vernon

Borough < < < = > = = = = = < = > = > > = < > = > =

North Huntingdon

Township = > = = < = = = < = > = > = = > = = = = > <

North Irwin Borough < < < = > = = = = = = = > = > > = < > = > =

Oklahoma Borough < < < = > = = = = = = = > = > < = < > = > =

Penn Borough < < < = > = > = = = < = > = > < = < > = > =

Penn Township < > < = > = = = = = = = > = < > = < = > = =

Rostraver Township = < = = = = = = = = = = > = = > = = = = = =

St. Clair Township = > = = > = > = = = < = = = = < = = = = > =

Salem Township = < = = > = > = = = > = > = = > = = = = > =

Scottdale Borough < < < = > = > = = = < = = = > < = < > = < =

Seward Borough < < < = > = = = = = < = = = > < = < > = > =

Sewickley Township = < = = < = > = = = = = > = = > = = = = < =

Smithton Borough < < < = > = > = = = < = > = > > = < > = < =

South Greensburg

Borough < < < = > = = = = = < = = = > < = < > = < =

South Huntingdon

Township = > = = < = > = = = = = > = = = = = = = < =

Southwest Greensburg

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Sutersville Borough < < < = > = > = = = < = > = > > = < > = < =

Trafford Borough < < < = > = > = = = = > > = > < = < > = > =

Unity Township = > = = > = = = = = = = = = = = = = = = = =



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Upper Burrell Township = < = = > = = = = = > = > = = < = = = = > =

Vandergrift Borough < < < = > = = = = = = = > = > < = < > = > =

Washington Township = < = = = = = = = = = = > = = < = = = = > =

West Leechburg Borough < < < = = = = = = = = = > = > < = < > = > =

West Newton Borough = > = = > = > = = = = = > < = > = = = = < =

Youngstown Borough < < < = > = = = = = < = = = > < = < > = > =

Youngwood Borough = < = < > < > = < = = = = < = < < = > = < >



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4.4.3 Potential Loss Estimates

Potential loss estimates for hazard events help a community understand the monetary value of what might be at

stake during a hazard event. Estimates are considered potential in that they generally represent losses that

could occur in a countywide hazard scenario. In events that are localized, losses may be lower, while regional

events could yield higher losses.

The data utilized to conduct the vulnerability assessment came from a variety of sources as noted throughout

each hazard profile and Appendix A. As summarized in the Methodology subsection, the 2010 U.S. Census

demographic data and default building inventory and associated replacement cost value of the structures and

contents in HAZUS MH 4.2 were used for Westmoreland County. Replacement cost value is the current cost

of returning an asset to its pre-damaged condition, using present-day cost of labor and materials. A

comprehensive critical facility inventory update was developed by gathering input from the Westmoreland

County Department of Public Safety, Westmoreland County Department of Information Systems, participating

municipalities, and the Planning Team.

Potential loss estimates provided in Section 4.3 (Hazard Profiles) were either based on historic losses, current-

condition losses, and/or predictive losses by performing spatial analyses in GIS and hazard probabilistic

modeling. In summary, HAZUS-MH was used to estimate potential losses for the earthquake, flood, and

tornado/wind storm hazards. For many of the hazards evaluated, historic data are not adequate to model future

losses at this time. For these hazards of concern, areas and inventory susceptible to specific hazards were

mapped and exposure was evaluated to help guide mitigation efforts (mitigation efforts are discussed further in

Section 6). Spatial analyses were conducted to assess potential exposure for hazards of concern with

delineated hazard areas: environmental hazards; flood, flash flood, and ice jam; landslide; nuclear incident;

subsidence and sinkhole; and wildfire. Where GIS data are not available for some hazards, a qualitative

analysis was conducted using the best-available data and professional judgment.

For this risk assessment, the loss estimates, exposure assessments, and hazard-specific vulnerability

evaluations rely on the best-available data and methodologies. Uncertainties are inherent in any loss estimation

methodology and arise in part from incomplete scientific knowledge concerning natural hazards and their

effects on the built environment. Uncertainties also result from the following:

1) Approximations and simplifications necessary to conduct such a study

2) Incomplete or dated inventory, demographic, or economic parameter data

3) The unique nature, geographic extent, and severity of each hazard

4) Mitigation measures already employed by the participating municipalities and the amount of advance

notice residents have to prepare for a specific hazard event

These factors can result in a range of uncertainty in loss estimates, possibly by a factor of 2 or more.

Therefore, potential exposure and loss estimates are approximate. These results do not predict precise results

and should be used to understand relative risk. Over the long-term, Westmoreland County will collect

additional data to assist in developing refined estimates of vulnerabilities to natural and non-natural hazards.

For more details on the potential loss estimates for each hazard, refer to Section 4.3 (Hazard Profiles).

4.4.4 Future Development and Vulnerability

Risk and vulnerability to natural and human-caused hazard events are not static. Risk will increase or decrease

as counties and municipalities see changes in land use and development as well as changes in population.



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Population change (in terms of total and demographics) and the age of the housing stock continue to be main

indicators of vulnerability change in Westmoreland County.

Westmoreland County experienced a 4-percent decrease in population from 2000 to 2017, as summarized in

Section 2. According to the U.S. Census 2000, 2010, and 2018, over 75 percent of the municipalities in

Westmoreland County are projected to see a decrease in population whereas 15 municipalities are projected to

see an increase.

Continued analysis of the age structure in Westmoreland County will provide deeper understanding on future

vulnerability to at-risk populations. Approximately 21 percent of Westmoreland County’s population is age 65

or older. As these residents continue to age in the County, they may have increased special needs. For

example, many residents in this age bracket may be unable to drive; therefore, development of special

evacuation plans for them may be necessary. They may also have hearing or vision impairments that could

hinder their reception of emergency instructions. Both older and younger populations are at higher risks for

contracting certain diseases. Westmoreland County’s combined populations under 5 years of age and over 65

constitute approximately 25.7 percent of its population.

Approximately 2.3 percent of Westmoreland County’s population lives in group quarters, which are communal

settings that can include inmates in a prison; students in a dorm; or elderly persons, or people with physical or

mental disabilities living in group-care homes. Many residents living in group quarters have special needs. It

is important to ensure that each group-living facility has its own emergency plan to account for the unique

needs of its residents during a hazard event.

Approximately 0.6 percent of Westmoreland County’s population is not proficient in English. Future hazard

mitigation strategies should consider addressing language barriers to ensure that all residents can receive

emergency instructions.

In addition, remote and sparsely-populated municipalities also face higher vulnerability to hazards because

they do not have easy access to care facilities or response personnel. For instance, the sparsely populated

municipality of Donegal Borough faces increased vulnerability to tornadoes, windstorms, and winter storms

due to isolation, access issues, and longer emergency response times.

The aging housing stock in Westmoreland County is another source of current and future vulnerability in many

hazard events. According to the U.S. Census, approximately 10.6 percent of the County’s residential

properties are vacant. Vacant buildings are more vulnerable to criminal activity. A total of 45,000 structures in

Westmoreland County were built earlier than 1940 (22 percent of the building stock). As discussed throughout

Section 4 (Risk Assessment), Westmoreland County can experience strong gusts of wind during windstorms,

tornadoes, hurricane, tropical storms, or Nor’easters. The structure of these older houses may be more at risk

of destruction under strong wind conditions. These structures may also be at risk during flooding and winter

storm events if the materials are either not strong enough to withstand the pressure or weight of the

precipitation, or are liable to leak, causing further risk of destruction to the house.

While any development increases the risk of damage and loss to natural hazards, a number of factors indicate

that this increase in risk is low and mitigated by existing federal, state, county, and local regulations, policies,

and programs. Twenty-nine municipalities in Westmoreland County have adopted the County’s Subdivision

and Land Development Ordinance (SALDO). Twenty-three municipalities have zoning regulations, and two

have the capability underway. The Westmoreland County Planning Commission reviews and reports on

subdivisions, land developments, comprehensive plans, and municipal land use ordinance amendments. This

broad range of planning review services is separated into two areas of activity: subdivision and land

development reviews and community planning reviews. Most types of reviews are presented to the



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commission for its consideration at a public meeting prior to them being forwarded on to the respective

municipalities and/or applicants.

Westmoreland County and its municipalities have identified areas of potential new urban growth and will work

with non-profit and private-sector partners to plan and pursue these projects. These areas are described in

Section 2 (County Profile). As development occurs in these areas, local officials will determine to which

hazards the proposed development is vulnerable, and will protect structures and infrastructure appropriately.

section 4.4 - hazard vulnerability summary · westmoreland county hazard mitigation plan 4.4-2...

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