section 4.4 - hazard vulnerability summary - hmp.lancema.ushmp.lancema.us/2019docs/27 section 4.4 -...

SECTION 4.4: HAZARD VULNERABILITY SUMMARY

Lancaster County Hazard Mitigation Plan 4.4-1 January 2019

4.4 HAZARD VULNERABILITY SUMMARY

This section describes the methodology and tools used to support the risk assessment process.

4.4.1 Methodology

The risk assessment process used for this hazard Mitigation Plan (HMP) update is consistent with the process

and steps presented in the Federal Emergency Management Agency (FEMA) 386-2, State and Local

Mitigation Planning How-to-Guide, Understanding Your Risks – Identifying Hazards and Estimating Losses

(FEMA 2001). This process identifies and profiles the hazards of concern and assesses the vulnerability of

assets (population, structures, critical facilities, and the economy) at risk in the community. A risk assessment

provides the foundation for the community’s decision makers to evaluate mitigation measures that can help

reduce the impacts of a hazard when one occurs (mitigation measures are described in Section 6). The risk

assessment process consists of the following steps:

Step 1: The first step of the risk assessment process is to identify the hazards of concern. FEMA’s current

regulations only require an evaluation of natural hazards. Natural hazards are natural events that threaten lives,

property, and other assets. Natural hazards often can be predicted to reoccur the same geographical locations

because they are related to weather patterns or physical characteristics of an area.

Step 2: The next step of the risk assessment is to prepare a profile for each hazard of concern. These profiles

assist communities in evaluating and comparing the hazards that can impact their area. Each type of hazard has

unique characteristics that vary from event to event. That is, the impacts associated with a specific hazard can

vary depending on the magnitude and location of each event (a hazard event is a specific, uninterrupted

occurrence of a particular type of hazard). Further, the probability of occurrence of a hazard in a given

location impacts the priority assigned to that hazard. Finally, each hazard will impact different communities in

different ways based on geography, local development, population distribution, age of buildings, and

mitigation measures already implemented.

Steps 3 and 4: To understand risk, a community must evaluate its assets (Step 3) and determine which assets

are exposed or vulnerable to the identified hazards of concern (Step 4). Hazard profile information—

combined with data regarding population, demographics, general building stock, and critical facilities at risk—

prepares the community to develop risk scenarios and estimate potential damages and losses for each hazard.

Critical facilities in Lancaster County are presented in Section 2.6 of this HMP.

Tools

To address the DMA 2000 requirements and better understand potential vulnerability and losses associated

with hazards of concern, Lancaster County used standardized tools combined with local, state, and federal data

and expertise to conduct the risk assessment. Tools used by Lancaster County to support the risk assessment

are described in the sections below.

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. (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 geographic

information system (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 utilities. To generate

this information, HAZUS-MH has default data for inventory, vulnerability, and hazards. These default data can

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

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

and social losses (such as 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 current and future data output, 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 2015a). More information on HAZUS-MH is available at https://www.fema.gov/hazus.

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

losses) for the earthquake and tornado/windstorm hazards, as well as an expected or estimated distribution of

losses (mean return period losses) for the earthquake; flood, flash flood, and ice jam; and tornado/windstorm

hazards. The probabilistic hazard analyses generate estimates of damage and loss for specified return periods.

For annualized losses, HAZUS-MH 3.2 calculates the maximum potential annual dollar loss resulting from

various return periods averaged on a per-year basis. The analysis consists of 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, flood, and wind hazards) each year is

calculated.

The following custom methodologies in HAZUS-MH 3.2 (HAZUS-MH) were used to assess potential

exposure and losses associated with hazards of concern for Lancaster County:

• Inventory: The default demographic data in HAZUS-MH 3.2, based on the 2010 U.S. Census, were used

for the potential loss analysis (such as for sheltering and injuries) for each hazard model.

The default building inventory in HAZUS-MH 3.2 was used for Lancaster County. The occupancy classes

available in HAZUS-MH 3.2 were condensed into categories (residential, commercial, industrial,

agricultural, religious, government, and educational) to facilitate the analysis and the presentation of

results. Residential loss estimates address both multi-family and single-family dwellings. Building

replacement cost values are based upon 2014 RS Means Company, Inc. (RS Means) valuations. Both

layers were merged and used to calculate the exposure for each hazard.

An updated critical facility inventory was also developed and incorporated into HAZUS-MH, replacing

the default essential facility (police, fire, schools, etc.), transportation facility, and utility inventories for

the earthquake, flood, and wind hazard models. This comprehensive inventory was developed by

gathering input from the Lancaster County Emergency Management Agency and Lancaster County IT

Department - GIS Division, participating municipalities, and the Planning Team.

The “user-defined facilities” category includes all assets that Lancaster County deemed critical to include

in the inventory and that do not fit within a pre-defined HAZUS-MH facility category. These facilities

include County buildings, senior care facilities, and municipality-owned buildings.

https://www.fema.gov/hazus



HAZUS-MH 3.2 incorporates two types of census block-based data: homogenous and dasymetric.

Homogenous census blocks display the full extent of each block, while the dasymetric census blocks have

had homogenous undeveloped areas (bodies of area, forests, etc.) removed. The dasymetric blocks were

developed to provide more accurate loss estimates by excluding uninhabited and undeveloped areas of a

census block.

• Earthquake: A probabilistic assessment was conducted for Lancaster County for the 500-year mean return

period (MRP) in HAZUS-MH 3.2 to analyze the earthquake hazard and provide a range of loss estimates

for Lancaster County. Default demographic and building stock data from HAZUS-MH 3.2 and updated

critical facility inventories were used for the analysis. The probabilistic method uses information from

historic earthquakes and inferred faults, locations, and magnitudes and computes the probable ground-

shaking levels that may be experienced during a recurrence period by Census tract.

As noted in the HAZUS-MH Earthquake User Manual, “Uncertainties are inherent in any loss estimation

methodology. They arise in part from incomplete scientific knowledge concerning earthquakes and their

effects upon buildings and facilities. They also result from the approximations and simplifications that are

necessary for comprehensive analyses. Incomplete or inaccurate inventories of the built environment,

demographics and economic parameters add to the uncertainty. These factors can result in a range of

uncertainly in loss estimates produced by the HAZUS Earthquake Model, possibly at best a factor of two

or more” (FEMA 2015a). However, the HAZUS potential loss estimates are acceptable for the purposes

of this HMP.

Ground shaking is the primary cause of earthquake damage to manmade structures, and soft soils amplify

ground shaking. One contributor to the site amplification is the velocity at which the rock or soil transmits

shear waves (S-waves). The National Earthquake Hazard Reduction Program (NEHRP) developed five

soil classifications that impact the severity of an earthquake, ranging from A to E. Soil classified as A

represents hard rock that reduces ground motions from an earthquake, and E represents soft soils that

amplify and magnify ground shaking and increase building damage and losses. NEHRP soil classifications

were not available for Lancaster County at the time of this analysis. Soils were estimated as NEHRP soil

Type D across Lancaster County as a conservative approach to this risk assessment. Groundwater was set

at a depth of 5 feet (default setting). Damages and losses due to liquefaction, landslide, or surface fault

rupture were not included in this analysis.

• Flood, Flash Flood, and Ice Jam: The FEMA Digital Flood Insurance Rate Map (DFIRM) dated April

2016 was used to evaluate exposure for the 1- and 0.2-percent annual chance flood events and determine

potential future losses for the 1 percent annual chance event in Lancaster County. These flood events are

generally considered by planners and evaluated under federal programs such as the National Flood

Insurance Program (NFIP). A 1 percent annual chance flood depth grid was generated by FEMA (Risk

Map 2016) for use in HAZUS-MH 3.2 to estimate potential losses within the County. Additional areas of

the floodplain not included in the depth grid were generated utilizing the FEMA floodplains and digital

elevation model (DEM) generated from the County’s 5-foot contour data.

• Tornado/Windstorm: After reviewing historic data, a HAZUS-MH 3.2 probabilistic analysis was

performed for the 100-year and 500-year MRP events to analyze the wind hazard losses for Lancaster

County. The probabilistic hurricane hazard contains data on historic hurricane events and wind speeds;

the model activates a database of thousands of potential storms with tracks and intensities reflecting the

full spectrum of Atlantic hurricanes observed since 1886, and then identifies those storms with tracks

associated with the County. It also includes surface roughness and vegetation (tree coverage) maps for the

County. Surface roughness and vegetation data support the modeling of wind force across various types of land surfaces. Default demographic and building stock data (homogenous census block) from HAZUS-

MH 3.2 and updated critical facility inventories were used for the analysis.



ESRI ArcGIS

For the following hazards, ArcGIS was used to assess potential exposure for hazards of concern with

delineated hazard areas in Lancaster County. The defined hazard areas were overlaid upon the asset data

(population, building stock, critical facilities) to estimate the exposure to each hazard. The limitations of these

analyses are recognized, and as such the analyses are only used to provide a general estimate:

• Environmental Hazards: The Federal 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 are

susceptible to spilling at the facilities or during 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 ¼ mile buffer around the Interstate, State, and U.S. roadways. A ¼ mile buffer was also placed around

the pipelines and rail lines provided by the County GIS Division. Additionally, SARA II facilities were

provided by the County, along with specified vulnerability radii for each facility. These in conjunction with

the ¼ roadway buffer were used to estimate the exposure to the asset data.

• Nuclear Incident: Populations and critical facilities within the Plume Exposure Pathway Emergency

Planning Zone (EPZ), which is a 10-mile radius around the facility, or the Ingestion Exposure Pathway

EPZ, which is a 50-mile radius around the facility, of a nuclear power plant are susceptible to a nuclear

incident. Lancaster County is located within both the Plume Exposure EPZ the Ingestion Exposure

Pathway EPZs of the Three Mile Island Nuclear Power Plant located in Dauphin County, PA and the

Peach Bottom Nuclear Power Plant in York County, PA. The entire County is located within the 50-mile

EPZ for both nuclear power plants; therefore, the 10-mile EPZs were used to define the hazard area for a

nuclear incident.

• 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 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 each hazard.

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 Lancaster County were selected and considered in this plan. However, the

communities in Lancaster 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 October 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 identifies 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 Lancaster County’s hazards and each

hazard’s RF.



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

Source: PEMA 2013



Table 4.4-2. Risk Ranking for Lancaster 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 3 3 3.4

Tornado,

Windstorm 3 3 4 4 2 3.2

Invasive Species 4 2 4 1 4 3.1

Pandemic 2 4 4 1 4 3.1

Utility

Interruptions 4 3 4 4 2 3.1

Winter Storm 3 2 4 2 2 2.7

Environmental

Hazards 4 2 1 4 2 2.6

Drought 3 1 4 1 4 2.5

Hailstorms 3 1 4 4 1 2.5

MO

DE

RA

TE

Transportation

Accidents 4 1 2 4 1 2.4

Radon Exposure 3 1 3 1 4 2.3

Earthquake 2 1 4 4 1 2.2

Wildfire 4 1 1 4 1 2.2

Subsidence and

Sinkholes 3 1 1 4 3 2.1

LO

W

Nuclear Incidents 1 2 2 4 2 1.9

Dam Failure 1 1 1 3 2 1.3

Based on these results, there are 9 high-risk hazards, 5 moderate-risk hazards, and 2 low-risk hazards in

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

(see 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 Lancaster County and whether their risk

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



Table 4.4-3. Jurisdictional Risk by Municipality

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2.5 2.2 3.4 2.5 3.1 3.1 2.3 2.1 3.2 2.2 2.7 1.3 2.6 1.9 2.4 3.1

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

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

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

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

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

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

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

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

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

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

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

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

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

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

East Cocalico Township = = = = = = = > = = > = = < > =

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

East Drumore Township = = = = = = > < = < = = > > = =

East Earl Township > = > = > = = > = > = = < < = =

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

East Lampeter Township > = > = = = = > = = = > = < > >



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2.5 2.2 3.4 2.5 3.1 3.1 2.3 2.1 3.2 2.2 2.7 1.3 2.6 1.9 2.4 3.1

East Petersburg Borough = = = = = = = = = = = < = < = =

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

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

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

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

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

Fulton Township < < < < < < < < < > > > < > > >

Lancaster City < = = = < > = > = > = = > < = =

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

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

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

Little Britain Township = = = = = = = < = < = = > > = =

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

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

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

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

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

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

Mount Joy Borough < = = = < > = > = > = = > < = =

Mount Joy Township = = < = = = = = = = = = = > > =

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

New Holland Borough < = < = < > = < = < = = > < = =



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2.5 2.2 3.4 2.5 3.1 3.1 2.3 2.1 3.2 2.2 2.7 1.3 2.6 1.9 2.4 3.1

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

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

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

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

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

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

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

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

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

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

Terre Hill Borough < = < = = = = < = < = < = < = =

Upper Leacock Township > = = = = = = = = = = = > < > =

Warwick Township = = = = = = = = = = = = = < = =

West Cocalico Township < = < < = = > < > > = < > = < =

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

West Earl Township > = = = > = = = = = = = > < > =

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

West Lampeter Township = = < = < = > > = < = < = = = =



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 (2015) and associated replacement cost value of the

structures and contents in HAZUS-MH 3.2 were used for Lancaster 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 Lancaster

County Emergency Management Agency, Lancaster County Department of Information Technology – GIS

Division, 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

hurricane/tropical storm/Nor’easter 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, Lancaster 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.



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

indicators of vulnerability change in Lancaster County.

Although Lancaster County experienced a 14.41 percent increase in population from 2000 to 2016, as

summarized in Section 2, according to the Pennsylvania Population Projections from the Center for Rural

Pennsylvania, the population in Lancaster County is projected to increase over the coming decades.

Unfortunately, the population projections are not available at the municipal-level.

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

vulnerability to at-risk populations. Approximately 16.2 percent of Lancaster 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. Lancaster County’s combined under-5-years-of-age and over-65 populations constitute

approximately 22.8 percent of its population.

Approximately 2.5 percent of Lancaster County’s population lives in group quarters, which are communal

settings that can include inmates in a prison, students in a dorm, or elderly or mentally disabled in group-care

homes. Many residents living in group quarters have special needs. It is important to ensure that each group-

quarter facility has its own emergency plan to account for the unique needs of its residents during a hazard

event.

Approximately 5.8 percent of Lancaster 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 as easy access to care facilities or response personnel. For instance, the sparsely populated

municipalities such as Drumore Township face increased vulnerability to tornadoes, windstorms, and winter

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

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

hazard events. According to the American Community Survey Estimate (2012-2016, there are over 45,000

structures in Lancaster County built earlier than 1940 (22 percent of the building stock). As discussed

throughout the risk assessment (Section 4), Lancaster 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 these 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. 44 municipalities in Lancaster County have adopted subdivision regulations and 45

municipalities have adopted local zoning regulations. The Lancaster 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

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

municipalities and/or applicants.



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

with nonprofit and private-sector partners to plan and pursue these projects. A spatial analysis was conducted

utilizing the urban growth areas and the delineated hazard areas to determine if any are potentially at risk.

Where the urban growth areas intersect with the delineated hazard areas is shown in Figure 4.4-1 through

Figure 4.4-4.



Figure 4.4-1. Urban Growth and Hazard Areas - West



Figure 4.4-2. Urban Growth and Hazard Areas – North/East



Figure 4.4-3. Urban Growth and Hazard Areas – Central/South



Figure 4.4-4. Urban Growth and Hazard Areas - Central

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