Final Hazard Vulnerability Assessment ... - Dauphin County

Dauphin County
December 2010
Hazard Vulnerability
Assessment and Mitigation Plan
Update
Report Volume

DAUPHIN COUNTY HAZARD VULNERABILITY
ASSESSMENT AND MITIGATION PLAN UPDATE
REPORT VOLUME
PREPARED FOR
DAUPHIN COUNTY EMERGENCY MANAGEMENT AGENCY
911 GIBSON BOULEVARD
STEELTON, PENNSYLVANIA 17113
PREPARED BY
449 EISENHOWER BOULEVARD, SUITE 300
HARRISBURG, PENNSYLVANIA 17111
DECEMBER 27, 2010
R09-0054.000

TABLE OF CONTENTS
PAGE
1.0 INTRODUCTION ............................................................................................................. 1
1.1 HAZARD MITIGATION PLANNING AND THE DISASTER MITIGATION
ACT OF 2000 ...................................................................................................... 1
1.2 MULTI-JURISDICTIONAL PLAN ADOPTION ..................................................... 2
1.3 MULTI-JURISDICTIONAL PLANNING PARTICIPATION ................................... 3
1.4 THE PLANNING PROCESS ............................................................................... 6
1.5 THE UPDATING PROCESS ............................................................................... 6
2.0 HAZARD IDENTIFICATION AND RISK ASSESSMENT ................................................ 8
2.1 HAZARD IDENTIFICATION ................................................................................ 8
2.2 HAZARD EVENT PROFILES ............................................................................ 10
2.3 VULNERABILITY ASSESSMENT: IDENTIFYING ASSETS ............................ 40
2.4 VULNERABILITY ASSESSMENT: ESTIMATING POTENTIAL LOSSES ........ 44
2.5 VULNERABILITY ASSESSMENT: ANALYZING DEVELOPMENT
TRENDS ............................................................................................................ 53
2.6 MULTI-JURISDICTIONAL RISK ASSESSMENT .............................................. 55
3.0 HAZARD MITIGATION GOALS .................................................................................... 56
3.1 HIGH-PRIORITY HAZARD MITIGATION GOALS ............................................ 56
3.2 MEDIUM-PRIORITY HAZARD MITIGATION GOALS ....................................... 57
3.3 LOW-PRIORITY HAZARD MITIGATION GOALS ............................................. 58
4.0 CAPABILITY ASSESSMENT ........................................................................................ 59
4.1 INTRODUCTION ............................................................................................... 59
4.2 INSTITUTIONAL CAPABILITY .......................................................................... 59
4.3 LEGAL CAPABILITY ......................................................................................... 60
4.4 FISCAL CAPABILITY ........................................................................................ 61
4.5 POLITICAL CAPABILITY .................................................................................. 63
4.6 TECHNICAL CAPABILITY ................................................................................ 64
5.0 HAZARD MITIGATION STRATEGY ............................................................................. 65
5.1 IDENTIFICATION AND ANALYSIS OF HAZARD MITIGATION
MEASURES ...................................................................................................... 65
5.2 IMPLEMENTATION OF HAZARD MITIGATION MEASURES ........................ 116
5.3 MULTI-JURISDICTIONAL HAZARD MITIGATION STRATEGY ..................... 130
6.0 PLAN MAINTENANCE PROCEDURES ..................................................................... 134
6.1 MONITORING, EVALUATING, AND UPDATING THE PLAN ......................... 134
6.2 IMPLEMENTATION THROUGH EXISTING PROGRAMS .............................. 135
6.3 CONTINUED PUBLIC INVOLVEMENT........................................................... 136
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LIST OF APPENDICES
APPENDIX A - PLAN ADOPTION RESOLUTIONS
APPENDIX B - PUBLIC MEETING DOCUMENTATION
APPENDIX C - PA DCNR WILDFIRE HAZARD ASSESSMENT DOCUMENTATION
APPENDIX D - CRITICAL FACILITIES INVENTORY
APPENDIX E - REGIONAL HAZARD EVENT PROFILE MAPPING
APPENDIX F - REPRESENTATIVE FLOODPLAIN STRUCTURE LOSS ESTIMATES AND
BENEFIT-COST ANALYSES RESULTS/SUPPORTING DOCUMENTATION
APPENDIX G - CAPABILITY ASSESSMENT MATRIX
APPENDIX H - CONSERVATION ZONING/SUBDIVISION DESIGN INFORMATION
APPENDIX I - REPRESENTATIVE FLOODPLAIN STRUCTURE HAZARD MITIGATION
OPPORTUNITY FORMS
APPENDIX J - FEMA’S EMERGENCY MANAGEMENT GUIDE FOR BUSINESS AND
INDUSTRY
APPENDIX K - PA DCED GROWING SMARTER TOOLKIT
APPENDIX L - LOCAL MITIGATION PLAN CROSSWALK
APPENDIX M - NON-NATURAL HAZARDS SCOPE OF WORK
APPENDIX N - REPETITIVE LOSS STRUCTURE MAPPING
APPENDIX O - PLAN UPDATE ADOPTION RESOLUTIONS
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LIST OF FIGURES
NO. DESCRIPTION PAGE
1-1 LOCATION MAP ............................................................................................................ 4
2-1 FLOODING HAZARDS ................................................................................................ 12
2-2 PEAK ANNUAL SUSQUEHANNA RIVER STAGE RECORDED AT
HARRISBURG, PA (1900-1949) .................................................................................. 21
2-3 PEAK ANNUAL SUSQUEHANNA RIVER STAGE RECORDED AT
HARRISBURG, PA (1950-2001) .................................................................................. 22
2-4 GEOLOGIC HAZARDS ................................................................................................ 30
2-5 WILDFIRE HAZARDS .................................................................................................. 38
5-1 STEEL I-BEAMS AND JACKS ARE INSTALLED IN PREPARATION FOR
LIFTING THE HOUSE ................................................................................................. 87
5-2 THE HOUSE, SUPPORTED ON THE I-BEAMS, IS RAISED ON THE JACKS ........... 87
5-3 NEW MASONRY PIERS ARE CONSTRUCTED TO SUPPORT THE HOUSE,
AND THE BASEMENT IS FILLED WITH DIRT............................................................ 88
5-4 WHEN THE HOUSE HAS BEEN RAISED TO THE DESIRED HEIGHT, THE
NEW MASONRY PIERS ARE COMPLETED .............................................................. 88
5-5 A TYPICAL DRY FLOODPROOFED HOUSE ............................................................. 90
5-6 A TYPICAL WET FLOODPROOFED HOUSE ............................................................. 93
5-7 A TYPICAL DRY HYDRANT ...................................................................................... 104
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LIST OF TABLES
NO. DESCRIPTION PAGE
1-1 MITIGATION STEERING COMMITTEE MEMBERS ..................................................... 3
1-2 MULTI-JURISDICTIONAL PLANNING PARTICIPATION .............................................. 5
2-1 DAUPHIN COUNTY DISASTER HISTORY ................................................................... 9
2-2 DAUPHIN COUNTY HAZARD IDENTIFICATION SUMMARY TABLE ........................ 10
2-3 DAUPHIN COUNTY NFIP PARTICIPATION STATUS BY MUNICIPALITY ................ 17
2-4 PEAK ANNUAL SUSQUEHANNA RIVER DISCHARGE AND STAGE
RECORDED AT HARRISBURG, PA (1900-2001) ....................................................... 19
2-5 PA DCNR WILDFIRE HAZARD ASSESSMENT SCORES FOR SELECT
DAUPHIN COUNTY MUNICIPALITIES ....................................................................... 39
2-6 DAUPHIN COUNTY ASSET VULNERABILITY BY MUNICIPALITY ........................... 42
2-7 DAUPHIN COUNTY NFIP POLICY CLAIMS DATA BY MUNICIPALITY ..................... 47
2-8 FLOOD DEPTH-DAMAGE FUNCTIONS FOR RESIDENTIAL
REPRESENTATIVE STRUCTURES ........................................................................... 49
2-9 FLOOD DEPTH-DAMAGE FUNCTIONS FOR COMMERCIAL/INDUSTRIAL
REPRESENTATIVE STRUCTURES ........................................................................... 50
2-10 SUMMARY OF 100-YEAR FLOOD LOSS ESTIMATE RESULTS FOR
RESIDENTIAL REPRESENTATIVE STRUCTURES ................................................... 51
2-11 SUMMARY OF 100-YEAR FLOOD LOSS ESTIMATE RESULTS FOR
COMMERCIAL/INDUSTRIAL REPRESENTATIVE STRUCTURES ............................ 51
5-1 SUMMARY OF BENEFIT-COST ANALYSIS RESULTS FOR RESIDENTIAL
REPRESENTATIVE STRUCTURES ........................................................................... 82
5-2 SUMMARY OF BENEFIT-COST ANALYSIS RESULTS FOR
COMMERCIAL/INDUSTRIAL REPRESENTATIVE STRUCTURES ............................ 82
5-3 DAUPHIN COUNTY PROPERTY PROTECTION GUIDE ........................................... 83
5-4 RELOCATION COST GUIDE ...................................................................................... 84
5-5 ELEVATION COST GUIDE .......................................................................................... 89
5-6 DRY FLOODPROOFING COST GUIDE ...................................................................... 91
5-7 WET FLOODPROOFING COST GUIDE ..................................................................... 95
- iv -

LIST OF TABLES
(CONTINUED)
NO. DESCRIPTION PAGE
5-8 PRIORITIZED HAZARD MITIGATION ACTION PLAN .............................................. 117
5-9 MULTI-JURISDICTIONAL HAZARD MITIGATION STRATEGY ................................ 131
LIST OF PHOTOGRAPHS
NO. DESCRIPTION PAGE
1 FLOODING ALONG MARKET STREET IN THE CITY OF HARRISBURG
DURING THE 1936 ST. PATRICK’S DAY FLOOD ...................................................... 24
2 FLOODING ALONG CAMERON STREET IN THE CITY OF HARRISBURG
DURING THE 1936 ST. PATRICK’S DAY FLOOD ...................................................... 24
3 FLOODING OF THE GOVERNOR’S MANSION ALONG NORTH
FRONT STREET IN THE CITY OF HARRISBURG DURING THE
1972 AGNES EVENT. .................................................................................................. 25
4 RESCUE WORK ON MACLAY STREET IN THE CITY OF
HARRISBURG DURING THE 1972 AGNES EVENT. ................................................. 25
5 RESIDENTIAL DAMAGE IN WASHINGTON TOWNSHIP CAUSED BY
WICONISCO CREEK DURING THE 1972 AGNES EVENT. ....................................... 26
6 FLOODING OF THE SHIPOKE AREA OF HARRISBURG DURING THE
1972 AGNES EVENT. .................................................................................................. 26
7 ICE ACCUMULATION ALONG THE SUSQUEHANNA RIVER DURING
THE 1996 ICE JAM EVENT ......................................................................................... 28
8 THE END RESULT OF ICE JAM FLOODING ON THE WALNUT STREET
BRIDGE DURING THE 1996 ICE JAM EVENT. .......................................................... 28
9 SURFACE DAMAGE CAUSED BY A LARGE SINKHOLE ALONG
ROUTE 422 IN DERRY TOWNSHIP. .......................................................................... 31
10 KNOWN LANDSLIDE HAZARD AREA ALONG ROUTE 147
NORTH OF MILLERSBURG IN UPPER PAXTON TOWNSHIP .................................. 31
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1.0 INTRODUCTION

1.0 INTRODUCTION
1.1 HAZARD MITIGATION PLANNING AND THE DISASTER MITIGATION ACT OF 2000
With the passage of the Disaster Mitigation Act of 2000 (DMA 2000) (Public Law 106-
390) on October 10, 2000, the Federal Emergency Management Agency (FEMA) established
new criteria for the development of multi-Hazard Mitigation Plans at the state and local level on
a pre-disaster basis. Specifically, Section 322, Mitigation Planning, of the Robert T. Stafford
Disaster Relief and Emergency Assistance Act (42 U.S.C. 5121-5206), enacted by Section 104
of DMA 2000, provided new and revitalized approaches to hazard mitigation planning. This
section also emphasized the importance of coordinating state and local hazard mitigation planning
and implementation activities and continued the requirement for a state Hazard Mitigation
Plan as a condition for receiving federal disaster assistance. In addition, Section 322 allows the
amount of funding available through FEMA’s Hazard Mitigation Grant Program (HMGP) to be increased
for states that demonstrate an increased commitment to comprehensive hazard mitigation
planning and implementation through the development of an “enhanced” Hazard Mitigation
Plan. Finally, Section 322 authorized the expenditure of up to 7% of the HMGP funds available
to each state to be used for the completion of Hazard Mitigation Plans on a pre-disaster basis.
Also important is the fact that state and local governments were not eligible for post-disaster
HMGP funds after November 1, 2004, without an approved Hazard Mitigation Plan.
To implement the hazard mitigation planning criteria developed under DMA 2000, FEMA
published an Interim Final Rule in the Federal Register at 44 CFR Part 201. This Interim Final
Rule clearly established the hazard mitigation planning criteria for state and local plans. According
to Section 201.1(b) of FEMA’s Interim Final Rule, the purpose of hazard mitigation
planning is for state, local, and Indian tribal governments to identify the natural hazards that
impact them, to identify actions and activities to reduce any losses from those hazards, and to
establish a coordinated process to implement the plan, taking advantage of a wide range of
resources. FEMA’s Interim Final Rule describes three general types of Hazard Mitigation Plans.
These include Standard State Mitigation Plans, Enhanced State Mitigation Plans, and Local
Mitigation Plans. Regardless of the type of plan, the hazard mitigation planning process must
be open to the public and must provide an opportunity for the public to comment on the plan
during the drafting stage and prior to plan approval. Involving the public in the hazard mitigation
planning process allows for the development of a more comprehensive approach to reducing
the effects of disasters, which is essential to the development of an effective plan.
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Given the above law, regulations, and policies, the Dauphin County Commissioners
prepared a multi-jurisdictional Hazard Mitigation Plan for the County’s 40 municipalities in
February 2004. Similar to the 2004 plan, this Hazard Mitigation Plan Update includes documentation
of the process that was used to develop the plan, including how it was prepared, who was
involved, and how the public was involved. In accordance with FEMA guidance, the risk assessment
part of the plan includes a description of all natural hazards that affect the County and
the County’s vulnerability to those hazards. Following the risk assessment, a mitigation strategy
for reducing the potential losses is also included. The mitigation strategy identifies and analyzes
a comprehensive range of specific mitigation actions to reduce the effects of each identified
hazard. The mitigation strategy also includes an updated action plan that ranks the identified
projects in terms of their priority status, identifies who is responsible for administering the
projects, and outlines a schedule for project implementation. Finally, the Hazard Mitigation Plan
Update includes documentation of an established plan maintenance process and proof of plan
adoption by Dauphin County and its municipalities.
Adoption of this Hazard Mitigation Plan Update by Dauphin County and its municipalities
not only allows each municipality to continue its eligibility for disaster mitigation grant funds but
also provides each municipality with an ongoing thorough understanding of its vulnerability to
various hazards and an updated blueprint for mitigating the damaging effects of those hazards.
The mitigation planning regulations at 44 CFR Part 201.6(d)(3) state that a local jurisdiction
must review and revise its plan to reflect development changes, progress of local efforts,
and priority changes within five years in order to remain eligible for grant funding. This update
must undergo the same approval process as the original plan. FEMA issued two guidance
documents which were referenced for this update which include information on plan update
requirements. Those guidance documents are titled Local Multi-Hazard Mitigation Planning
Guidance (July 2008) and Multi-Jurisdictional Mitigation Planning (FEMA 386-8, August 2006).
1.2 MULTI-JURISDICTIONAL PLAN ADOPTION
In order for a multi-jurisdictional Hazard Mitigation Plan to be approved, each jurisdiction
(municipality) that is included in the plan must have its governing body adopt the plan before
submission to the State and FEMA, even when a regional agency (Dauphin County Emergency
Management Agency – DEMA) has the authority to prepare such a plan on behalf of the respective
jurisdictions. As such, the Hazard Mitigation Plan of 2004 was formally adopted by Dauphin
County and 38 of its municipalities (see Table 1-2). Copies of the County and municipal adop-
- 2 -

tion resolutions for the original plan are included in the appendices and summarized in Table
1-2. Information regarding the adoption of the plan update is also included.
1.3 MULTI-JURISDICTIONAL PLANNING PARTICIPATION
Dauphin County’s 40 municipalities (see Figure 1-1) were involved throughout both the
original hazard mitigation planning process as well as the plan update process. Municipal
emergency management coordinators were informed about the project at their monthly training
sessions. Municipal officials provided information related to existing codes and ordinances,
known hazard areas, the severity of past hazard events, and the location of critical facilities.
Table 1-1 shows the municipal and County officials who participated in the plan update through
the Steering Committee.
TABLE 1-1
MITIGATION STEERING COMMITTEE MEMBERS
MUNICIPALITY/ORGANIZATION
Dauphin County EMA
Dauphin County EMA
Dauphin County EMA
Dauphin County EMA
Londonderry Township
Lower Swatara EMA
Susquehanna River Basin Commission
Millersburg Borough
Tri-County Regional Planning Commission
NAME
Kirsten Cohick
Stephen Shaver
Chris Fisher
Jack Harlacker
Steve Letavic
Alan Knoche
Ben Pratt
Skip Wingard
Janine Park
The municipalities also participated in the identification and ranking of project planning goals
(see Chapter 3). Municipal officials also provided input on the hazard identification and risk
assessment and hazard mitigation strategy sections of the plan. Municipal involvement in this
hazard mitigation planning program was further emphasized during review of the draft plan and
by adopting the final plan (see Table 1-2). The municipalities also participated in the plan
update by filling out a table showing what suggested mitigation measures they have completed
since the original plan.
- 3 -

MIFFLIN
PILLOW
BERRYSBURG
LYKENS
GRATZ
³
WILLIAMS
WICONISCO
WILLIAMSTOWN
UPPER PAXTON
WASHINGTON
LYKENS
MILLERSBURG
tu 209
ELIZABETHVILLE
OP 25 JACKSON
OP 325
OP 441
JEFFERSON
HALIFAX
RUSH
HALIFAX
WAYNE
Legend
Dauphin County
OP 225 OP 283 OP 341
tu 11 tu 322
City
OP 849 OP 743
OP 325
REED
OP
OP 225
147 MIDDLE PAXTON
EAST HANOVER
DAUPHIN
WEST HANOVER
OP 39
OP 743
SUSQUEHANNA
§¨¦ 81
LOWER PAXTON
§¨¦ 81 §¨¦ 83 §¨¦ 283
SOUTH HANOVER
Borough
Township
OP 443 OP 230
§¨¦ 83 §¨¦ 76
HARRISBURG
PENBROOK
PAXTANG
HUMMELSTOWN
DERRY
SWATARA
STEELTON
LOWER SWATARA
CONEWAGO
HIGHSPIRE
MIDDLETOWN
ROYALTON
LONDONDERRY
PENNSYLVANIA
DAUPHIN COUNTY
SKELLY and LOY, Inc. December 2009 Figure 1-1
Dauphin County Hazard Vulnerability
Assessment and Mitigation Plan
LOCATION MAP
Dauphin County, Pennsylvania
Job No: R09-0054
Scale: 1" = 15,000'

TABLE 1-2
MULTI-JURISDICTIONAL PLANNING PARTICIPATION
MUNICIPALITY TITLE NAME
ORIGINAL PLAN
PARTICIPATION 2
ORIGINAL PLAN
ADOPTION DATE
UPDATE PLAN
PARTICIPATION 3
Berrysburg Borough EMC Shawn Leitzel X Apr-04 X
Conewago Township EMC George Giangi X Dec-04 X
Dauphin Borough EMC John Bahnweg X May-04
Derry Township EMC Dave Holl X Feb-08 X
East Hanover Township EMC John Nelligan X Aug-04 X
Elizabethville Borough EMC Russ Walborn X Oct-04 X
Gratz Borough EMC James Lesher X
Halifax Borough EMC Jeff Enders X Aug-04 X
Halifax Township EMC Mike Decker X May-04 X
Harrisburg City EMC-ACTING Dan Soulier X Oct-04 X
Highspire Borough EMC Terry Watts X Oct-04 X
Hummelstown Borough EMC Robert Martindill X Jun-04 X
Jackson Township EMC Don Shutt X May-04 X
Jefferson Township EMC Barry Everly X Oct-04 X
Londonderry Township 1 EMC Sam Naples X Jun-04 X
Lower Paxton Township EMC Ralph Palm X Sep-04 X
Lower Swatara Township 1 EMC Alan Knoche X Aug-04 X
Lykens Borough EMC Donna Cowden X Aug-04
Lykens Township EMC Norm Bakelaar X X
Middle Paxton Township TOWN MGR Julie Seeds X May-04 X
Middletown Borough EMC Tom Foreman X Dec-04 X
Mifflin Township EMC Shawn Leitzel X Feb-09 X
Millersburg Borough 1 EMC John Brabits X May-04 X
Paxtang Borough EMC Robin Bloss X Jun-04 X
Penbrook Borough EMC Bob Rhoads X Nov-04 X
Pillow Borough EMC Shawn Leitzel X Jul-04
Reed Township EMC Don Shutt X Sep-04 X
Royalton Borough EMC Tom Foreman X Nov-04
Rush Township EMC Ronald Koppenhaver X Aug-04
South Hanover Township EMC Dave Williard X Nov-04 X
Steelton Borough EMC Tim Lehman X Jun-04 X
Susquehanna Township EMC Brad Reist X Jun-04 X
Swatara Township EMC Darrin Robinson X Oct-04 X
Upper Paxton Township 1 EMC John Brabits X Jun-04 X
Washington Township EMC Russ Walborn X Jun-04 X
Wayne Township EMC Don Shutt X Sep-04 X
West Hanover Township EMC Bill McCahan X May-04 X
Wiconisco Township EMC Ron Pinchorski X Jul-04
Williams Township EMC John McCready X Jun-04 X
Williamstown Borough EMC John McCready X Jun-04 X
UPDATE PLAN
ADOPTION DATE
1 Municipality directly represented on the Mitigation Steering Committee
2 Planning participation includes meeting attendance and receipt of planning materials
3 Update Plan Participation includes meeting attendance, status review of hazard mitigation measures, or draft plan review.

1.4 THE PLANNING PROCESS
DEMA was responsible for the development and coordination of the original Hazard
Mitigation Plan. To accomplish this task, DEMA formed a Mitigation Steering Committee
comprised of representatives from FEMA, the Pennsylvania Emergency Management Agency
(PEMA), various Dauphin County agencies, the Tri-County Regional Planning Commission
(TCRPC), the Susquehanna River Basin Commission (SRBC), and the City of Harrisburg. The
Mitigation Steering Committee met on a monthly basis and the plan was developed over the
course of one year. For the update, a Mitigation Steering Committee was once again formed
with several of the same members, and it met on a monthly basis for six months.
Efforts were made to solicit both municipal and public input throughout the planning
process. Two series of public meetings were held during the original formation of the plan and
one public meeting was held during the plan update process. Identical northern and southern
County meetings were held to provide better accessibility for all of the County’s residents.
Feedback received from the public proved valuable in the development of the plan as well as
the updating of the plan. Two meetings were also held for the Municipal Emergency Management
Coordinators on June 11 and 16, 2009. Documentation of both the EMC and public
meetings is included in the Appendices.
A number of organizations and individuals provided support through the development of
the plan including the County office of economic development, the County public relations office,
TCRPC, SRBC, PEMA, FEMA, the Pennsylvania Department of Conservation and Natural
Resources (PA DCNR), the Pennsylvania Department of Community and Economic Development
(PA DCED), the Harrisburg Authority, and the National Weather Service (NWS). This
support included provision of background materials, such as the County Comprehensive Plan,
statistical event data, post-damage reports, historic event data, and hazard assessments;
coordination with local municipalities and businesses; and administrative support with mailings
and other information distribution efforts.
1.5 THE UPDATING PROCESS
The regulations intend that the approved plan update serve as a stand-alone complete
and current plan, not as an amendment to the original document. The plan update must provide
information on the progress to fulfill the commitments and activities intended to be implemented
through the adoption of the previously approved plan.
- 6 -

The plan update includes all newly identified hazards as well as more detailed information
on existing hazards where it became available. Information for the plan update was
gathered using the same resources that were utilized during the original plan development
process, including available mapping from local and state agencies, municipal planning documents,
and through coordination with DEMA staff and municipal representatives.
By evaluating each municipality to determine what commitments were met, the plan
update was able to better identify goals and objectives as well as to re-prioritize some activities.
- 7 -

2.0 HAZARD IDENTIFICATION
AND RISK ASSESSMENT

2.0 HAZARD IDENTIFICATION AND RISK ASSESSMENT
2.1 HAZARD IDENTIFICATION
Based on historical occurrences specific to Dauphin County and the surrounding area,
the Mitigation Steering Committee developed a listing of known natural hazards to be addressed
in this plan. These known natural hazards were identified through an extensive process that
involved the following:
input from the individual Steering Committee members, local officials, and
the public;
coordination with various federal, state, and local agencies;
a review of past disaster declarations at the federal and state level specific
to Dauphin County (see Table 2-1);
analysis of hazard identification and risk assessment publications at the
state and local level;
limited field reconnaissance;
Internet research; and
Review of NFPA 1600 hazards.
In addition, DEMA’s Geographic Information System (GIS) database was used as an
important resource in identifying and mapping the County’s infrastructure, critical facilities, and
land uses. Data from this source and GIS data made available from other project participants
(i.e., FEMA and PA DCNR) were used to determine those hazards that present the greatest risk
to the County. Table 2-2 summarizes the identification of these hazards.
Due to the lack of record of occurrence for these events, natural hazards such as
avalanches, coastal storms, coastal erosion, tsunamis, glacier, tidal surge, seiche, sandstorms,
famine, and volcanoes are not addressed in this plan. Similarly, expansive soils were also
excluded from the hazard identification and risk assessment.
- 8 -

TABLE 2-1
DAUPHIN COUNTY DISASTER HISTORY
DATE HAZARD EVENT ACTION
February 1958 Heavy Snow Governor’s Proclamation
March 1963 Ice Jam Governor’s Proclamation
September 1963 Drought Governor’s Proclamation & President’s Declaration of Major Disaster
January 1966 Heavy Snow Governor’s Proclamation
February 1972 Heavy Snow Governor’s Proclamation
June 1972 Flood (Agnes) Governor’s Proclamation & President’s Declaration of Major Disaster
April 1975 High Winds None
September 1975 Flood (Eloise) Governor’s Proclamation & President’s Declaration of Major Disaster
October 1976 Flood Governor’s Proclamation & President’s Declaration of Major Disaster
April 1977 Tornado None
January 1978 Heavy Snow Governor’s Proclamation
February 1978 Blizzard Governor’s Proclamation
March 1979 Nuclear Facility Incident (TMI) None
January 1990 Vernon Street Fire SBA-Physical Disaster Loans & Economic Injury Disaster Loan
June 1991 Steelton Hotel Fire Governor’s Proclamation & President’s Declaration of Major Disaster
July 1991 Drought Governor’s Proclamation
March 1993 Blizzard Governor’s Proclamation & President’s Declaration of Emergency
January 1994 Severe Winter Storms Governor’s Proclamation & President’s Declaration of Major Disaster
January 1996 Flooding Governor’s Proclamation & President’s Declaration of Major Disaster
January 1996 Severe Winter Storms Governor’s Proclamation & President’s Declaration of Major Disaster
July 1999
September 1999
Drought
Flash Flooding (Tropical
Depression Dennis)
Governor’s Proclamation, Individual Assistance, HMGP-Amended to
include all 67 counties for an agricultural disaster
Governor’s Proclamation & President’s Declaration of Major Disaster
September 1999 Hurricane Floyd Governor’s Proclamation & President’s Declaration of Major Disaster
February 2002 Drought and Water Shortage Governor’s Proclamation
February 2003 Severe Winter Storm Governor’s Proclamation
September 2003 Hurricane Isabel Governor’s Proclamation
May 2004
Heavy Rain, High Winds and
Flooding
SBA – Physical Damage and Economic Injury
September 2004 Tropical Depression Ivan Governor’s Proclamation & President’s Declaration of Major Disaster
September 2005 Hurricane Katrina
Governor’s Proclamation & President’s Declaration of Emergency for
Public Assistance
June 2006 Flooding Governor’s Proclamation & President’s Declaration of Major Disaster
September 2006 Tropical Depression Ernesto Governor’s Proclamation
February 2007 Severe Winter Storm Governor’s Proclamation
April 2007 Severe Winter Storm Governor’s Proclamation
Source: PEMA
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TABLE 2-2
DAUPHIN COUNTY HAZARD IDENTIFICATION SUMMARY TABLE
HAZARD HOW IDENTIFIED WHY IDENTIFIED
Dam Failure
Drought
Flooding
Hurricanes/
Tropical Storms
Land
Subsidence
Landslides
Severe Storms
(thunderstorms,
hailstorms, and
blizzards)
Tornadoes
Wildfires
Analysis of the County’s Vulnerability
Assessment
Review of past disaster declarations
Input from the Susquehanna River Basin
Commission
Review of past disaster declarations
Review of Flood Insurance Rate Mapping
Identification of NFIP repetitive loss
properties
Analysis of post-disaster/risk assessment
reports
Local knowledge/public input
Review of past disaster declarations
Analysis of post-disaster/risk assessment
reports
Local knowledge/public input
Input from the Pennsylvania Geological
Survey
Analysis of geologic mapping
Local knowledge/public input
Input from the Pennsylvania Geological
Survey
Input from the Pennsylvania Department
of Transportation
Review of past disaster declarations
Input from the National Weather Service
Local knowledge/public input
Review of past disaster declarations
Input from the National Weather Service
Review of past disaster declarations
Input from the Pennsylvania Department
of Conservation and Natural Resources
Presence of DeHart Dam within the
County
Severity and frequency of past events
Large number of County residents on
private wells
Severity and frequency of past events
Locally acknowledged as the most
prevalent potentially devastating natural
hazard event
Presence of the Susquehanna River
and its many tributary streams
Severity of the flood-related damages
caused by the 1972 (Agnes) and 1975
(Eloise) events
Presence of carbonate rock units
Known sinkhole locations within the
County
Mountainous topography within the
County
Known landslide locations within the
County
Severity and frequency of past events
Occurrence of a significant event
during the planning period (February
2003)
Severity and frequency of past events
Frequency of past events
Presence of large forested tracts
within the County
2.2 HAZARD EVENT PROFILES
2.2.1 Dam Failure
Dam failures can produce an extremely dangerous flood situation due to the large
volume of high-velocity water that is released and the minimal amount of time (if any) for conducting
warning and evacuation procedures. Breaching often occurs within hours after the first
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visible signs of a failure. As such, four of the top five killer floods in the country (including the
1977 Johnstown flood in Pennsylvania) were the result of dam failures. Dam failures typically
occur for one of three reasons.
The foundation fails due to seepage, settling, or earthquake.
The design, construction, materials, or operation were deficient.
Flooding exceeds the capacity of the dam’s spillway.
Proper design, regular maintenance and routine inspection can go a long way in preventing a
dam failure.
Dam failure presents a low-probability flooding hazard for Dauphin County due to the
presence of the DeHart Dam/Reservoir on Clarks Creek in Rush Township (see Figure 2-1), the
Raystown Dam/Lake on the Raystown Branch of the Juniata River in Huntington County, and a
number of smaller scale dams or impoundments throughout the County. These smaller scale,
low hazard dams include Hidden Valley Dam in Middle Paxton Township, Yingst Dam in West
Hanover Township, Jacobs Creek Dam in Derry Township, and Hershey Medical Center Campus
Pond No. 1 Dam in Derry Township. These smaller scale dams/impoundments do not
represent a significant hazard due to their small capacities and inundation areas and were not
analyzed in detail in either the original plan or the plan update. However, the DeHart Dam is a
rolled earthfill structure constructed in 1940 for the purpose of creating a water supply reservoir
for the City of Harrisburg. The dam is owned by the Harrisburg Authority and operated by the
City of Harrisburg. At normal pool elevation, the dam maintains approximately 23,000 acre-feet
of water and an associated reservoir that is approximately 4.5 miles long. The Raystown Dam
is an earth and rockfill dam constructed for the purposes of flood control; recreation; and enhancement
of fisheries, wildlife, and water quality. The dam is operated and maintained by the
U.S. Army Corps of Engineers (USACE), Baltimore District. At normal pool elevation, the dam
maintains approximately 514,000 acre-feet of water and an associated reservoir that is approximately
30 miles long. A sudden break of either of these dams would cause flash flooding in
select areas of the County.
Analysis of the DeHart Dam Emergency Action Plan (2008) indicated that the inundation
area from a sudden break of DeHart Dam would be bounded on the north by Route 325 and on
the south by Third and Middle Mountains from the dam to the Susquehanna River for a total
distance of approximately 17.06 miles (topographic mapping of this estimated inundation area is
contained in the DeHart Dam Emergency Action Plan, which is available for inspection at the
office of the Harrisburg Authority). As of 1997, this area contained 112 residences and 10
highway bridges. A “sunny day” break (i.e., dam failure under normal pool elevation conditions)
- 11 -

MILLERSBURG
Wiconisco Creek
Mahantango Creek
Clarks Creek
DeHart Reservoir
OP
OP 225 849 OP 325 DAUPHIN
Manada
OP Creek
§¨¦ 39 81
Beaver
Creek
§¨¦ 81 Paxton
Creek
§¨¦ 83
PENBROOK
HARRISBURG
OP 743
§¨¦ 83 §¨¦ 283
Sus quehanna River
HALIFAX
Powell Creek
Armstrong Creek
Stony Creek
OP 25 LYKENS
OP 325
Fishing Creek
Wiconisco Creek
tu 11 OP 147 OP 743
tu 322
tu 22 tu 209
PILLOW
BERRYSBURG
ELIZABETHVILLE
PAXTANG
GRATZ
HUMMELSTOWN
Swatara Creek
WILLIAMSTOWN
³
Bow
Creek
OP 225 OP 283 OP 341
OP 443 OP 230
Swatara
Creek
Spring
Creek
STEELTON
HIGHSPIRE
§¨¦ 76
MIDDLETOWN
ROYALTON
Conewago Creek
Legend
Interstates
Streams
US Routes
PA Routes
State Roads
Municipal Boundaries
Floodplains
100-Year
500-Year
SKELLY and LOY, Inc. December 2009
Dauphin County Hazard Vulnerability
Assessment and Mitigation Plan
Job No: R09-0054
FLOODING HAZARDS
Dauphin County, Pennsylvania
Figure 2-1
Scale: 1" = 15,000'

of DeHart Dam would impact all 112 residences, blow out 9 of the 10 highway bridges, and
result in a 38-foot flood wave reaching the Susquehanna River in approximately 2 hours and 47
minutes. A “Probable Maximum Flood” break (i.e., dam failure caused by upstream flooding
and increased pool elevation conditions) of the DeHart Dam would impact all 112 residences
plus an additional 57 residences, blow out all 10 highway bridges, and result in a 14-foot flood
wave reaching the Susquehanna River in approximately 2 hours and 14 minutes. As such, the
Mitigation Steering Committee selected the “Probable Maximum Flood” break as the maximum
extent of DeHart Dam failure hazard for study in this plan.
Analysis of the Raystown Dam Emergency Plan (January 2009) indicated that those
Dauphin County municipalities located along the Susquehanna River south of the Juniata River
confluence at Clark’s Ferry would experience significant overbank flooding of the Susquehanna
River if a “Spillway Design Flood” with dam failure (i.e., dam failure caused by upstream flooding
and increased pool elevation conditions) were to occur at the Raystown Dam. The USACE
estimated that if such an event were to occur, the Susquehanna River at the Market Street
Bridge in Harrisburg would begin to experience increased flows approximately 13.6 hours after
the dam failure. The estimated peak stage of the Susquehanna River at the Market Street
Bridge (26.8 feet NGVD) would occur approximately 24.0 hours after the dam failure. Given
that the City of Harrisburg starts to flood when the River hits 17 feet, this estimated peak river
stage (26.8 feet) would result in flooding impacts comparable to the 1996 ice jam flood that
occurred on the Susquehanna River. Areas inundated by such an event would closely match
the 100-year floodplain of the Susquehanna River. As such, the Mitigation Steering Committee
selected the “Spillway Design Flood” with dam failure as the maximum extent of Raystown Dam
failure hazard for study in this updated plan as well as the original plan.
2.2.2 Drought
Much like the rest of Pennsylvania, Dauphin County is subject to periodic droughts that
impact the County’s ability to meet all of its water needs. As defined by FEMA, a drought is the
consequence of a natural reduction in the amount of precipitation expected over an extended
period of time, usually a season or more in length. Unlike some hazards, droughts are not
specific to certain parts of the County. Rather, a drought is likely to impact the County in a
relatively uniform fashion with only minor localized variations in rainfall amounts of specific
storm events. As such, it is not practical to map drought occurrence at the county level.
The effects of a drought can be far-reaching and typically include reduced productivity of
aquatic resources, mandatory water use restrictions, well failures, cutbacks in industrial production,
agricultural losses, and limited recreational opportunities. Numerous indices have been
- 13 -

developed to define the severity of droughts. Some of the more commonly used indices include
the Palmer Drought Severity Index, the Crop Moisture Index, departure from normal precipitation,
accumulated departure from normal stream flow, low-flow frequency estimates, groundwater
levels, and lake/water storage levels. Ultimately, the severity of a drought event is determined
by its aerial extent when combined with its intensity and duration. Similarly, the
frequency or probability of occurrence of a given drought event is calculated as a function of its
intensity and duration (i.e., how bad was it and for how long). As such, the statistical analysis
for determining the probability of drought events is similar to that used for calculating the return
interval of flood events and results in a “percent chance” for a more severe event to occur.
As noted in Pennsylvania’s Draft Drought Management Plan, soil moisture information is
provided by the National Oceanic and Atmospheric Administration (NOAA) via the Palmer
Drought Severity Index. The Palmer Index is a computed value based on a number of meteorological
and hydrological factors; it is compiled weekly for Pennsylvania by the Climate Prediction
Center of the National Weather Service. Within Pennsylvania, Palmer values of -2.00 to -2.99
indicate a drought watch status, values of -3.00 to -3.99 indicate warning, and values of -4.00
and less indicate emergency. The Palmer Indices are available for all ten Palmer regions of the
state. Northern Dauphin County is located in Palmer Region 5, while southern Dauphin County
is located in Palmer Region 3. These indices, along with several other information sources, are
used by the Commonwealth Drought Task Force to monitor drought conditions. During significant
drought events, Dauphin County actively monitors and participates in the mitigative recommendations
established by the Drought Task Force.
Analysis of Dauphin County’s disaster history (see Table 2-1) indicates that there have
been four disaster declarations since 1958 as the result of drought. These events occurred in
1963, 1991, 1999, and most recently in 2002. No new drought events have occurred since the
original hazard plan. The 2002 drought event was actually initiated in the summer of 2001,
which had a significant number of days with an above-average temperature and below-average
precipitation followed by one of the driest winters on record. Groundwater levels, stream flows,
and lake/reservoir levels were already well below normal going into the spring of 2002. An
abnormally dry spring, followed by an extremely dry summer with a record number of days
above 90 degrees gave rise to one of the worst droughts the lower Susquehanna River basin
has ever experienced. As such, the Mitigation Steering Committee selected the 2002 drought
event as the maximum magnitude of drought hazard for study in this plan. Given that there has
been no additional droughts which have occurred to use as a model, the update was done using
the 2002 drought as the maximum magnitude drought study for the update plan as well.
Coordination with the SRBC indicated that the 2002 drought event resulted in record low
groundwater levels, record low stream flow levels, record low reservoir/lake levels, and an
- 14 -

unprecedented number of private homeowner well failures in the lower Susquehanna River
basin. Many local farmers suffered crop losses of 70 to 100 percent. Analysis of USDA crop
insurance performance statistics for Dauphin County from the period 1981 to 2008 indicates that
the 2002 drought event accounted for the highest agricultural loss claims recorded during the
27-year period. In 2002, more than $2,000,000 in claims were paid on 258 policies, resulting in
a $19.00 benefit for every $1.00 paid in premium. In addition, water-dependent industries, such
as nurseries, suffered losses while others had operational concerns due to the record low
stream flow conditions.
2.2.3 Flooding
As with most communities along the Susquehanna River, Dauphin County is susceptible
to the problems and hazards associated with flooding. Within Dauphin County, most flooding
typically occurs when a channel (i.e., a river, creek, stream, or ditch) receives too much water
and the excess flows over its banks onto the adjacent floodplain. This type of flooding is known
as riverine (or overbank) flooding and is generally a problem only where there has been development
in the floodplain. Riverine flooding in an undisturbed floodplain is a natural process that
has been occurring for millennia with little or no adverse consequences. It is only in recent
history that natural floodplains have been altered by human encroachment, giving rise to
flooding as a potentially devastating natural hazard. Within Dauphin County, there are numerous
places where homes, businesses, and even industries have been constructed in a floodplain.
As such, flooding is arguably the most geographically/topographically influenced and
potentially devastating natural hazard that Dauphin County must face.
In addition to basic riverine/overbank flooding (such as occurs on the Susquehanna
River, Mahantango Creek, and Swatara Creek), Dauphin County is also susceptible to a modified
form of riverine/overbank flooding known as flash flooding. Unlike the Susquehanna River,
which may take up to two or more days to rise and crest, many of the County’s inland streams
and watercourses are subject to flash flooding. Flash floods occur in hilly and mountainous
areas where surface water runoff enters a drainage channel during and/or immediately following
a significant storm event or in urban areas where pavement and drainage improvements speed
runoff to a stream. As such, flash flooding is characterized by a rapid rise in water levels and
higher velocity flows. Within Dauphin County, flash floods occur in the northern mountains on
such streams as Wiconisco Creek and Rattling Creek and in the more urbanized area surrounding
the City of Harrisburg on such streams as Paxton Creek and the Lawnton Branch of Spring
Creek. Flash floods tend to be particularly dangerous and destructive because there is typically
little or no warning time and people are caught unaware. All flash floods strike quickly and end
- 15 -

swiftly. The most recent damaging flash flooding event occurred in Derry Township on June 1,
2007. There were seven residential structures that were affected, resulting in approximately
$500,000 in total damages.
Floods caused by ice jams also occur within Dauphin County. Ice jam flooding is
comparable to flash flooding in that the formation of an ice jam causes water upstream to rise
rapidly. When the jam releases, sudden flooding occurs downstream. Ice jams can occur
during fall freeze-up when ice begins to form, during midwinter when channels freeze solid and
form anchor ice, and during spring melt when the breakup of surface ice results in large, floating
masses of ice. The force of impact from ice carried by floodwaters typically causes more
damage to buildings, bridges, and other structures than open-water flooding.
Figure 2-1 indicates that Dauphin County has a well-developed drainage network
consisting of numerous first-, second-, and third-order streams. Several larger watercourses
(e.g., Mahantango Creek, Wiconisco Creek, Paxton Creek, Swatara Creek, Conewago Creek,
and the Susquehanna River) also traverse the County. As evidenced by Figure 2-1, most of
these watercourses have delineated floodplains established by FEMA through the National
Flood Insurance Program (NFIP). These delineated floodplains show the estimated area of
inundation associated with the 100- and 500-year storm events.
For most communities that participate in the NFIP (see Table 2-3), FEMA has prepared
a detailed Flood Insurance Study (FIS). The FIS presents water surface elevations for floods of
various magnitudes, including the flood that has a 1-percent probability of being equaled or
exceeded in any given year (also called the 100-year flood or base flood) and the flood that has
a 0.2-percent probability of being equaled or exceeded in any given year (also called the 500-
year flood). The water surface elevation of the 100-year flood event is called the base flood
elevation (BFE). BFEs and the boundaries of the 100- and 500-year floodplains are shown on
the participating community’s Flood Insurance Rate Mapping (FIRM). For participation in the
NFIP, FEMA has established the 100-year floodplain as the regulatory standard for local floodplain
management purposes. FEMA is currently completing updates for the 100-year floodplain
mapping. However, at the time of the print of this update such mapping was not available. As
such, the Mitigation Steering Committee selected the same 100-year floodplain which was used
in the original plan (see Figure 2-1) as the maximum magnitude of flood hazard for study in this
plan.
It is important to note that the City of Harrisburg is involved in the NFIP Community
Rating System (CRS) program which is a voluntary program administered by FEMA that recognizes
and encourages communities to implement floodplain management initiatives which
exceed federal flood insurance standards. Currently, the City of Harrisburg is a Class 6 municipality,
the highest in Pennsylvania and among the top 7% of participating communities across
- 16 -

the county. The primary incentive and benefit to the participating municipality is a reduction in
flood insurance premium rates. The City has just re-submitted for its five-year CRS update.
The City has many policies and programs dedicated to flood protection, floodplain management,
and emergency management. Activities identified in this year’s update include adopting current
building codes, incorporating educational materials into water bill mailings, and keeping logs of
all incoming calls regarding flooding for follow-up whenever possible. The City offers advice
and assistance through the Bureau of Codes to property owners regarding ways to reduce
flooding effects to their property.
TABLE 2-3
DAUPHIN COUNTY NFIP PARTICIPATION STATUS BY MUNICIPALITY
MUNICIPALITY
COMMUNITY
ID
DATE OF
ENTRY
CURRENT
EFFECTIVE MAP
POLICIES
IN FORCE*
INSURANCE
IN FORCE ($)*
TOTAL PREMIUM
PAID ($)*
Berrysburg Borough N/A N/A N/A 0 0 0
Conewago Township 422406 04/30/86 04/30/86 3 658,000 791
Dauphin Borough 420375 04/15/77 04/15/77 22 3,478,000 20,421
Derry Township 420376 09/30/77 09/30/77 55 12,505,000 35,505
East Hanover Township 420377 01/16/80 01/16/80 12 1,489,000 6,926
Elizabethville Borough 420378 06/25/76 06/25/76M 2 113,000 838
Gratz Borough 421591 12/14/79 12/14/79M 0 0 0
Halifax Borough 420379 09/05/79 09/05/79 8 794,000 3,146
Halifax Township 421592 11/03/82 11/03/82 13 1,575,000 6,680
Harrisburg City 420380 05/02/77 05/02/77 1,175 229,251,000 1,437,087
Highspire Borough 420381 04/15/77 12/11/81 201 25,184,000 175,577
Hummelstown Borough 420382 03/15/77 03/15/77 25 3,817,000 19,392
Jackson Township 421593 10/15/85 10/15/85M 1 30,000 355
Jefferson Township 421594 10/15/82 10/15/82M 1 70,000 180
Londonderry Township 420383 03/18/80 03/18/80 196 12,293,000 102,708
Lower Paxton Township 420384 04/15/81 04/15/81 70 14,005,000 76,597
Lower Swatara Township 420385 04/15/77 06/11/82 41 6,473,000 34,337
Lykens Borough 420386 09/03/80 09/03/80 131 9,339,000 79,925
Lykens Township 421595 10/15/85 10/15/85M 2 50,000 635
Middle Paxton Township 420387 08/15/79 08/15/79 125 16,470,000 99,937
Middletown Borough 420388 12/28/76 08/15/83 196 23,341,000 145,762
Mifflin Township 421596 06/25/76 06/25/76M 1 105,000 260
Millersburg Borough 420389 08/15/80 08/15/80 38 6,282,000 27,876
Paxtang Borough 420390 03/18/80 03/18/80 45 6,487,000 53,326
Penbrook Borough 420391 07/31/78 NSFHA 0 0 0
Pillow Borough 420392 11/19/87 11/19/87 0 0 0
Reed Township 420393 11/01/79 11/01/79 12 2,158,000 12,492
Royalton Borough 420394 04/15/77 04/15/77 48 6,122,000 31,136
Rush Township 421597 08/19/85 08/19/85M 0 0 0
South Hanover Township 420395 05/02/77 05/02/77 42 8,338,000 41,261
Steelton Borough 420396 04/15/77 04/15/77 96 12,463,000 98,362
Susquehanna Township 420397 04/15/77 04/15/77 268 50,649,000 310,156
- 17 -

TABLE 2-3
(CONTINUED)
MUNICIPALITY
COMMUNITY
ID
DATE OF
ENTRY
CURRENT
EFFECTIVE MAP
POLICIES
IN FORCE*
INSURANCE
IN FORCE ($)*
TOTAL PREMIUM
PAID ($)*
Swatara Township 420398 02/03/82 02/03/82 198 23,345,000 142,873
Upper Paxton Township 420399 09/05/79 09/05/79 20 2,460,000 15,692
Washington Township 421598 12/17/87 12/17/87 4 697,000 5,075
Wayne Township 421599 08/05/85 08/05/85M 0 0 0
West Hanover Township 421600 03/18/80 03/18/80 17 2,629,000 9,041
Wiconisco Township 421030 04/15/81 04/15/81 3 519,000 1,643
Williams Township 421601 10/15/85 10/15/85M 0 0 0
Williamstown Borough 420400 08/05/85 08/05/85M 2 420,000 593
TOTAL N/A N/A N/A 3,073 483,609,000 2,996,585
Source: NFIP PA Community Status Book and HUDEX Report.
*Data current through 3/1/09.
In regard to past flood events, Dauphin County experienced its worst flooding as a result
of tropical storms/hurricanes and snowmelt events. Tropical storms and hurricanes occur
between the months of June and November, with the peak season being September to October.
These storms bring torrential rains and high winds and often cause flash flooding as well as
overbank flooding of inland streams and rivers. Snowmelts typically occur between the months
of January and April. Because the ground often remains frozen under snow, it cannot absorb
the water from the melt, and large volumes of surface water runoff are produced. Extreme
flooding events can occur during snowmelts when additional rainfall combines with the snowmelt
runoff. Although some of the most notable floods (e.g., June 1972 and September 1975)
were the result of tropical storms (Agnes and Eloise, respectively), the majority of recorded flood
events are attributed to winter precipitation and snowmelt.
The U.S. Geological Survey (USGS) operates a gauging station on the Susquehanna
River at Harrisburg (Station No. 01570500) on City Island just below the Market Street Bridge.
Table 2-4 lists the peak annual discharge and stage values of the Susquehanna River from
1900 to 2001 as measured at the Harrisburg USGS gauging station. Figures 2-2 and 2-3
graphically show these annual peak river stages in relation to the calculated stages of the 10-,
50-, 100-, and 500-year flood events at the same location (as reported in the Harrisburg City
Flood Insurance Study, 1977. Analysis of these data indicates that major flood events with a
peak river stage greater than 21 feet at the Harrisburg gage have occurred on March 3, 1902;
March 19, 1936; May 29, 1946; March 12, 1964; June 24 1972 (Tropical Storm Agnes); September
27, 1975 (Tropical Storm Eloise); January 21, 1996; and September 19, 2004 (Tropical
Depression Ivan). A brief synopsis of some of these more notable events is provided below.
- 18 -

The St. Patrick’s Day Flood of March 1936 resulted from a combination of snowmelt and
rainfall. The majority of heavy rainfall associated with the flood occurred on March 17 and 18.
Two days of heavy rain, combined with surface runoff from that winter’s ice and snow deposits,
caused the river to rise well above flood stage. Flood levels exceeded all previous recorded
levels. At Harrisburg, flood levels peaked on March 19 when the gage recorded a peak stage of
29.23 feet and a maximum discharge of 740,000 cubic feet per second. The National Emergency
Council estimated that Pennsylvania incurred approximately $212,535,010 (1936) in
damages as a result of the St. Patrick’s Day Flood. In addition, 80 people were killed and
another 2,800 were injured (Mangan, 1936). Photograph Nos. 1 and 2 show some of the
devastating effects this flood had in the Harrisburg area.
Tropical Storm Agnes of 1972 is the storm of record for the Susquehanna River in
Dauphin County. Tropical Storm Agnes hit in June just after an earlier rainfall had saturated the
ground. Agnes brought as much as 18 inches of rain to some places in Pennsylvania, with
Harrisburg receiving a reported 15.25 inches, producing severe surface water runoff conditions
which caused abnormally high flows in local streams and tributaries. Most communities along
the River, including Dauphin County, experienced severe flooding. The USGS gage at Harrisburg
recorded a peak river stage of 32.57 feet and a peak discharge of 1,020,000 cubic feet per
second. Damage estimates indicate that the Susquehanna River basin (from Sunbury to York)
incurred approximately $832,662,000 (1972) in damages, with the Dauphin County area accounting
for approximately $183,787,000 (1972) of that total. It was estimated that Pennsylvania
incurred over $2 billion (1972) in damages and was so severely impacted that President
Richard Nixon declared the entire state a disaster area (Miller, 1974; Gannett Fleming, 1974).
Photograph Nos. 3 through 6 show some of the devastating effects this flood had on Dauphin
County.
In September of 1975, just three years after Agnes, Tropical Storm Eloise brought
flooding to the County. Tropical Storm Eloise moved inland over the Florida panhandle and
weakened rapidly. Remnants of Eloise spread northward and, on the 24th, one inch of rain fell
over most of the Susquehanna River basin. Flash flood watches were in effect as precipitation
was forecasted to be heavier the following day. The 25th brought between 4.5 and 6.5 inches
of rainfall over the basin, and widespread flooding occurred. The result of Tropical Storm Eloise
was the third-highest flood discharge on record. The USGS gage at Harrisburg recorded a peak
river stage of 23.82 feet on the 27th, just 8.75 feet less than the peak stage recorded during the
1972 Agnes event. In Harrisburg, floodwaters reached Second Street and flowed through
portions of the downtown district. Damage estimates indicate that the Susquehanna River basin
(from Sunbury to York) incurred approximately $26,300,000 (1975) in damages (USACE, 1976).
- 23 -

Photograph No. 1: Flooding along Market Street in the City of Harrisburg during the
1936 St. Patrick’s Day Flood. Photo courtesy of the SRBC.
Photograph No. 2: Flooding along Cameron Street in the City of Harrisburg during the
1936 St. Patrick’s Day Flood. Photo courtesy of the SRBC.

Photograph No. 3: Flooding of the Governor’s Mansion along North Front Street in the
City of Harrisburg during the 1972 Agnes Event.
Photograph No. 4: Rescue work on Maclay Street in the City of Harrisburg during the
1972 Agnes Event.

Photograph No. 5: Residential damage in Washington Township caused by
Wiconisco Creek during the 1972 Agnes Event.
Photograph No. 6: Flooding of the Shipoke area of Harrisburg during the 1972 Agnes
Event. Photo courtesy of the SRBC.

In 1996, snowmelt combined with rainfall led to a large-scale flash flooding event across
Pennsylvania. Over the winter, a blizzard occurred that froze the ground and left up to seven
feet of snow base. In January, temperatures climbed rapidly into the 60’s and caused the snow
to melt. In addition, heavy rains averaging between 1.2 and 3 inches fell over the area in a 6-
hour period. The frozen ground could not absorb the water from the melt or the rainfall, and
large amounts of surface water runoff were produced. To further compound the problem, large
floating masses of ice accumulated at the various river crossings (see Photograph No. 7),
creating obstructions to the flood flow. The center section of the Walnut Street Bridge from City
Island to the West Shore was washed away as a result of an ice jam (see Photograph No. 8).
The USGS gage at Harrisburg recorded a peak stage of 24.66 feet. Damage estimates for the
entire Susquehanna River basin as a result of this flood event were in the range of
$600,000,000 (NWS, 1998).
The remnants of Hurricane Ivan (downgraded to a Tropical Depression) reached Pennsylvania
on September 17, 2004, only one week after Hurricane Frances traveled through
Pennsylvania. Average rainfall amounts for Ivan were between three and six inches, although
some areas of Dauphin County recorded as much as eight inches within a 12-hour period.
Water elevations in the Susquehanna River at Harrisburg were 24.4 feet at its peak. Central
Pennsylvania saw flooding of many streams and tributaries which topped the elevations of the
1996 flood. Bald Eagle Creek and the Frankstown Branch of the Juniata River set all-time
record high water elevations for those streams. Two deaths occurred in Central Pennsylvania,
one in Mifflin County and one in Blair County. Flood damages across the state were over $260
million. Property damages within Dauphin County were estimated at $50 million (National
Climatic Data Center).
2.2.4 Hurricanes/Tropical Storms
As previously mentioned, Dauphin County experienced some of its worst flooding as the
result of hurricanes/tropical storms. While Dauphin County is located too far inland to be
impacted by all of the common hazards associated with a hurricane/tropical storm event (i.e.,
severe winds and coastal storm surge), it is susceptible to the significant rainfall and associated
flooding that accompanies these medium-probability events. Analysis of Dauphin County’s
disaster history (see Table 2-1) indicates that there have been eight disaster declarations since
1958 due to flooding associated with hurricane/tropical storm events. These events occurred in
1972 (Agnes), 1975 (Eloise), 1999 (Dennis), 1999 (Floyd), 2003 (Isabel), 2004 (Ivan), 2005
- 27 -

Photograph No. 7: Ice accumulation along the Susquehanna River during the 1996
Ice Jam Event. Photo courtesy of the SRBC.
Photograph No. 8: The end result of ice jam flooding on the Walnut Street Bridge
during the 1996 Ice Jam Event. Photo courtesy of the SRBC.

(Katrina), and 2006 (Ernesto). As previously mentioned, the June 1972 Hurricane Agnes event
resulted in the flood of record for the central and eastern portions of the Susquehanna River
basin with the Susquehanna River reaching a peak stage of 32.57 feet at Harrisburg. More
detailed information on hurricane/tropical storm-related flooding can be found in Section 2.2.3.
2.2.5 Land Subsidence
Subsidence is defined as the downward movement of surface material with little or no
horizontal movement. Subsidence can occur naturally due to the physical and chemical weathering
of certain types of bedrock or can be human-induced due to underground mining or
excessive pumping of groundwater. Regardless of the reason for occurrence, the overall effect
of a subsidence event is the same. That is, the development and eventual failure of a sinkhole,
which can cause significant structural damage if buildings and/or infrastructure are present.
Dauphin County is susceptible to land subsidence in two distinct regions but for two very
different reasons. The northeastern part of Dauphin County in Williams and Wiconisco Townships
periodically experiences land subsidence events as a result of past subsurface coal
mining operations. Similarly, the limestone belt area of Dauphin County in Paxtang Borough,
Swatara Township, Lower Swatara Township, Derry Township, and Hummelstown Borough periodically
experiences land subsidence events as a result of the underlying carbonate geology.
Figure 2-4 shows these two distinct areas in Dauphin County. Fortunately, the area of
past subsurface coal mining operations in Williams and Wiconisco Townships consists primarily
of State Game Land No. 264 and represents little to no subsidence hazard to personal property.
Conversely, the limestone belt area of Dauphin County comprises the intensely developed Hummelstown-Hershey
area and represents a significant subsidence hazard to personal property
and public infrastructure. As such, the Mitigation Steering Committee identified the limestone
belt area of the County as the maximum physical extent of subsidence hazard for study in this
plan. Recently, large portions of both state and local roads in Derry Township have been closed
due to extensive sinkhole damage. The sinkholes have been choked and the roads repaired.
GIS data provided by the PA DCNR Bureau of Topographic and Geologic Survey
allowed the locations of known sinkholes, surface depressions, and caves (typical subsidence
features in a limestone area) to be included in the County’s Geologic Hazard Mapping (see
Figure 2-4). This figure shows that there are 44 recognized occurrences of sinkholes within
Dauphin County. As is to be expected, the vast majority of these features are located within the
limestone belt area of the County. Photograph No. 9 shows some of the surface damage that
can result from the development of a sinkhole.
- 29 -

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SKELLY and LOY, Inc. December 2009 Figure 2-4
Dauphin County Hazard Vulnerability
Assessment and Mitigation Plan
GEOLOGIC HAZARDS
Dauphin County, Pennsylvania
Job No: R09-0054
Scale: 1" = 15,000'

Photograph No. 9: Surface damage caused by a large sinkhole along Route 422 in
Derry Township. Photo from Kochanov, W.E., 1999, Sinkholes in Pennsylvania,
Pennsylvania Geological Survey Educational Series 11, p. 16.
Photograph No. 10: Known landslide hazard area along Route 147 north of
Millersburg in Upper Paxton Township.

2.2.6 Landslides
As defined by FEMA, a landslide is the downward and outward movement of earth
materials reacting under the force of gravity. As such, “landslide” can be used to describe a
number of different types of events displaying different movement characteristics and involving
different materials. Rockslides, rock falls, mudflows, mudslides, debris flows, and debris
avalanches are all types of landslide events that involve different materials moving in a different
manner. Landslides typically occur when some factor (e.g., increased water content or change
in load) causes the force of gravity to outweigh the forces working to hold material in place,
resulting in the downslope movement of the subject material. Several natural and human
factors may contribute to or influence landslides. These factors include topography, geology,
precipitation, steepness of cut and fill slopes, and cut-slope stability.
According to the PA DCNR, “landslides cause damage to transportation routes, utilities,
and buildings and create travel delays and other side effects. Fortunately, deaths and injuries
due to landslides are rare in Pennsylvania. Almost all of the known deaths due to landslides
have occurred when rock falls or other slides along highways have involved vehicles. Storm
induced debris flows are the only other type of landslide likely to cause death and injuries. As
residential and recreational development increases on and near steep mountain slopes, the
hazard from these rapid events will also increase.”
Coordination with the PA DCNR Bureau of Topographic and Geologic Survey indicated
that most landslide events in Pennsylvania tend to be human-induced. Cut and fill slopes for
roadways, septic fields on sloped areas, seeps from detention areas/reservoirs, and clearing of
vegetation in sloped areas are all human-induced causes of landslide events. Within Dauphin
County, the local maintenance district of the Pennsylvania Department of Transportation
(PennDOT) identified one known location of previous landslide events. This known landslide
hazard area is located in a steep roadway cut along Route 147 north of Millersburg in Upper
Paxton Township (see Figure 2-4 and Photograph No. 10). As part of the mitigation measures
of the original Hazard Plan, a fence was installed to stabilize this area and to prevent sliding on
the roadway. Similarly, no other known landslide event locations were reported.
Figure 2-4 also shows areas in the County that have bedrock geology with poor cutslope
stability and areas with slopes greater than 15 percent. The combination of these two
factors results in the identification of potential landslide hazard areas at the County level. As is
to be expected, the vast majority of these potential landslide hazard areas are located in the
northern mountainous part of the County. The Mitigation Steering Committee identified these
- 32 -

potential landslide hazard areas, along with the one known landslide hazard area, as the
maximum physical extent of landslide hazard for study in this plan.
2.2.7 Severe Storms
Severe storms include thunderstorms, hailstorms, and blizzards and are considered a
high-probability occurrence for Dauphin County. Thunderstorms and hailstorms are generated
when a warm, moist air mass rises rapidly into the atmosphere as a result of some lifting force
(e.g., colliding weather fronts, sea breezes, or orographically due to mountains). As the warm,
moist air rises, it cools, and the moisture condenses, forming towering cumulonimbus clouds,
thunder, and lightning. When compared to hurricanes/tropical storms and winter storms,
thunderstorms affect relatively small areas. The typical thunderstorm is only 15 miles in diameter
and lasts an average of 30 minutes. However, despite their small size, every thunderstorm
should be considered dangerous. Every thunderstorm produces lightning, which kills more
people each year than tornadoes. Heavy rain from thunderstorms can lead to flash flooding.
Strong winds, hail, and tornadoes are also dangers associated with some thunderstorms. Of
the estimated 100,000 thunderstorms that occur each year in the United States, only about 10
percent are classified as severe. A thunderstorm is considered to be severe if it produces hail
at least ¾ inch in diameter, wind 58 miles per hour (mph) or higher, or tornadoes. Hailstorms
are an outgrowth of severe thunderstorms and cause nearly $1 billion in damage to property
and crops on an annual basis in the United States.
Coordination with the NWS indicated that, since 1950, Dauphin County reported 157
occurrences of thunderstorm-related wind damage and 41 occurrences of thunderstorm-related
hail in excess of ¾ inch in diameter. The largest hail ever reported in Dauphin County was
approximately 2.5 inches in diameter (August 7, 1986). The most damaging thunderstorm
Dauphin County has ever experienced occurred in July 1995, which resulted in wind gusts of 80
mph and approximately $1 million in damages. This complex of severe thunderstorms caused
considerable wind damage, especially in the Harrisburg area. Fallen trees damaged 25 cars
and blocked 34 streets in and around Harrisburg. The golf concession on City Island and the 2-
story 80-foot long cinder block wall at Kunkel Elementary School near Middletown were destroyed.
In addition, approximately 40,000 Pennsylvania Power and Light (PPL) customers in
Dauphin and Lancaster Counties lost power. As such, the Mitigation Steering Committee
selected this thunderstorm event as the maximum magnitude severe storm hazard to be studied
in this plan.
- 33 -

Dauphin County is also susceptible to blizzards and other severe winter storms (i.e.,
heavy snows and ice storms). Blizzards are severe winter storms that pack a combination of
blowing snow and wind resulting in very low visibilities. While heavy snowfalls and severe cold
often accompany blizzards, they are not required. Sometimes strong winds pick up snow that
has already fallen, creating a blizzard. Officially, the NWS defines a blizzard as large amounts
of falling or blowing snow with winds in excess of 35 mph and visibilities of less than ¼ mile for
an extended period of time (greater than 3 hours). Blizzards and other severe winter storms
can create a variety of dangerous conditions. Traveling by automobile can become difficult or
even impossible due to “whiteout” conditions and drifting snow. The strong winds and cold
temperatures accompanying these storms can be dangerous if people are exposed for any
length of time. Threats such as hypothermia and frostbite can lead to loss of fingers and toes or
cause permanent kidney, pancreas, and liver damage and even death.
Analysis of Dauphin County’s disaster history (see Table 2-1) indicates that there have
been 11 disaster declarations since 1958 due to severe winter storms (heavy snow and blizzards).
Coordination with the NWS indicated that Dauphin County has experienced 38 significant
winter storms involving snow and/or ice accumulations greater than 6 inches since 1994.
Most recently, Dauphin County experienced a severe winter storm in February 2003 that
resulted in almost 30 inches of accumulated snowfall and a disaster declaration by the Governor.
Snow removal in the City of Harrisburg cost in excess of $332,000 and took nearly a week.
Several winter storms have occurred since the original approved plan; however, none of them
had damages or snow and ice accumulations as excessive as the 2003 storm. As such, the
Mitigation Steering Committee chose to continue to use the 2003 winter storm event as the
maximum magnitude severe winter storm hazard for study in this plan.
In the last few years, Dauphin County has experienced several winter storms which have
had associated damaging winds. In January 2006, 54 mph winds were recorded in both Halifax
and Harrisburg. Property damages in Halifax totaled $10,000. At the end of 2006, in December,
there was an eight-mile long swath of wind-induced damage east of Halifax, with winds
recorded at 70 mph. A short-lived tornado also developed. Property damages exceeded
$200,000 from this storm. In December 2008, non-thunderstorm related wind gusts of up to 60
mph resulted in widespread power outages, structural damage, and vehicular damages from
fallen trees. Damages totaled $10,000 (National Climatic Data Center).
- 34 -

2.2.8 Tornadoes
A tornado is a rapidly rotating column of air extending from a thunderstorm to the ground
that has the potential to cause significant damage to anything in its path. Although tornadoes
occur in many parts of the world, these destructive forces of nature are found most frequently in
the United States east of the Rocky Mountains during the spring and summer months. In an
average year, 800 tornadoes are reported nationwide, resulting in 80 deaths and over 1,500
injuries. With wind speeds in excess of 250 mph, tornadoes are considered nature’s most
violent storms. Damage paths can be as wide as 1 mile and over 50 miles long.
Tornadoes are related to larger vortex formations and often form in convective cells such
as thunderstorms or in the right forward quadrant of a hurricane, far from the hurricane eye.
Tornadoes in the winter and early spring are often associated with strong frontal systems that
form in the central states and move east. Occasionally, large outbreaks of tornadoes occur with
this type of weather pattern. Several states may be affected by numerous severe thunderstorms
and tornadoes. It is interesting to note that tornadoes may appear nearly transparent
until dust and debris are picked up or a cloud forms in the funnel.
Analysis of Dauphin County’s disaster history indicated that, in April 1977, the County
experienced a tornado with enough force to warrant a disaster declaration. Coordination with
the NWS revealed that this particular tornado event was categorized as an F2 (113-157 mph
wind speeds) according to the Fujita Tornado Scale and resulted in an estimated $2.5 million
(1977) in damage. According to NWS data, there have been 14 additional documented tornadoes
in Dauphin County and 2 observed funnel clouds. The first known tornado occurred in
November 1918, was categorized as an F2, and resulted in a damage path that was 200 yards
wide and ½ mile long. The most recent tornado occurred in December 2006 in Halifax. This
storm was rated as an F1 and was approximately 2 miles long and 75 yards wide. Major
damages occurred to four businesses and one home. Moderate and minor damages occurred
to several dozen homes. Winds were in access of 100 mph, causing severe wind damage.
One fatality was recorded as the result of a tree falling on a car. Damages were nearly $2
million.
Of the 15 documented tornadoes that have occurred in Dauphin County, 7 have been
categorized as F2, 6 have been categorized as F1 (73-112 mph wind speeds), and 2 have been
categorized as F0 (40-72 mph wind speeds).
In August 2004, two F1 tornados occurred in Dauphin County, one outside of Harrisburg
and one outside of Hummelstown. Peak winds were recorded at 90 mph for both events. There
- 35 -

were no injuries or deaths; however, several homes were warranted uninhabitable. Both storms
were approximately 2 miles in length and between 200 to 400 yards wide. Combined damages
of both storms totaled $300,000.
Unlike some hazards, tornadoes are not specific to select parts of the County. Rather, a
tornado could strike in any part of the County, and at any time, and could cause as much or as
little damage as possible for the given magnitude event. As such, it is not appropriate to map
tornado occurrence as a method of profiling the hazard. Since an F2 has been the largest
tornado ever recorded in Dauphin County, the Mitigation Steering Committee selected this
magnitude as the maximum tornado hazard to be studied in this plan. According to the Fujita
Tornado Scale, a typical F2 tornado would result in considerable damage, including roofs torn
off houses, mobile homes destroyed, boxcars pushed over, and large trees snapped or uprooted.
It is important to note that an F3 tornado occurred immediately over the border of
Dauphin and Lebanon Counties, west of Campbelltown, on July 14, 2004. A total of 32 homes
were destroyed, 37 had significant damage, and another 50 homes and 9 farm buildings were
affected by the winds associated with the tornado. The tornado was eight miles long and onequarter
mile wide. Winds were estimated between 175 and 200 mph. There were 24 people
injured (one critically) during the event. Over 50 families required the assistance and shelter of
the Red Cross Mass Care Center which was established. Between 25,000 and 30,000 customers
lost power in Dauphin, Lebanon, and Berks Counties. Damages totaled $18 million.
2.2.9 Wildfires
On average, Pennsylvania experiences approximately 1,000 wildfires every year. The
vast majority of these wildfires (90 percent) is caused by people and could be easily prevented
by applying simple common-sense safety practices when using fire. Fortunately, it is rare in
Pennsylvania for a wildfire to consume structures. Rather, most Pennsylvania wildfires affect
forested areas in rural settings that have a minimal number of permanent structures. This is not
to say, however, that Pennsylvania is not susceptible to a wildfire event that could destroy a
significant number of structures. This is true now more than ever, as development encroaches
further into the rural countryside, often taking place in wooded mountainous settings. This
concept is particularly applicable to northern Dauphin County with its wooded, mountainous
setting and its ever-increasing development potential brought about by its close proximity to the
Harrisburg urban center.
- 36 -

Structures that are built in the wooded (and typically mountainous) settings adjacent to
more urbanized areas are in the wildfire danger zone known as the Wildland/Urban Interface.
As its name implies, the Wildland/Urban Interface is that general land area considered to be the
fringe of suburban development where houses and other structures are typically built in or at
least bordered by extensive tracts of undeveloped woodlands. Within Dauphin County, these
extensive tracts of undeveloped woodlands (many of which are State Game Land and State
Forest Land) are primarily located in the northern part of the County (see Figure 2-5) and are
considered to be wildfire hazard areas due to their mountainous topography and availability of
fuel. As such, structures built in the Wildland/Urban Interface are more at risk of being destroyed
by wildfire due to their close proximity to wildfire hazard areas.
Coordination with the PA DCNR Bureau of Forestry indicated that Dauphin County has
averaged approximately 25 wildfires per year over the past 6 years. On average, these wildfires
account for approximately 75 acres of burned area per year, which equates to an estimated
average burned area of 3 acres per fire. The largest wildfire in Dauphin County in the past 25
years resulted in approximately 200 acres of burned area. Figure 2-5 shows the likely areas of
Dauphin County that would be most susceptible to wildfires due to their forested land cover.
This figure also shows the Wildland/Urban Interface structures throughout the County
that would be subject to the greatest risk of destruction by wildfire. As such, the Mitigation
Steering Committee identified this wildfire hazard area as the maximum physical extent of
Dauphin County’s wildfire hazard to be studied in this plan.
To further define Dauphin County’s vulnerability to wildfire hazards, the PA DCNR
Bureau of Forestry completed wildfire hazard assessments for each of the townships shown on
Figure 2-5 that have potential wildfire hazard areas. These wildfire hazard assessments were
conducted in the field and evaluate each township’s risk (i.e., potential for a fire to start), hazard
(i.e., potential to burn/fuel loading), and value (i.e., potential for loss). These risk, hazard, and
value factors were then tallied to develop a combined wildfire hazard rating for each township.
Any township with a combined wildfire hazard rating >8 is considered to have a high wildfire
hazard potential. Townships with a combined wildfire hazard rating between 5 and 7 are
considered to have a moderate wildfire hazard potential. Any township with a combined wildfire
hazard rating

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Forested Area
SKELLY and LOY, Inc. December 2009 Figure 2-5
Dauphin County Hazard Vulnerability
Assessment and Mitigation Plan
Job No: R09-0054
WILDFIRE HAZARDS
Dauphin County, Pennsylvania
Scale: 1" = 15,000'

TABLE 2-5
PA DCNR WILDFIRE HAZARD ASSESSMENT SCORES
FOR SELECT DAUPHIN COUNTY MUNICIPALITIES
TOWNSHIP RISK 1 HAZARD 1 VALUE 1 COMBINED
RATING 2
FIREWISE
SCORE 3
Conewago M L M 5 N/A
Derry M M H 7 69
Halifax H H H 9 80
Jackson H H H 9 95
Jefferson H H H 9 101
Londonderry M M H 7 72
Lower Paxton M L H 6 N/A
Lower Swatara M M M 6 N/A
Lykens H H M 8 101
Middle Paxton H H H 9 101
Mifflin H M M 7 96
Reed M H M 7 N/A
Rush H H H 9 118
South Hanover M L H 6 N/A
Susquehanna M M H 7 71
Swatara L M M 5 N/A
Upper Paxton H M M 7 118
Washington H M H 8 94
Wayne H M H 8 84
West Hanover H M H 8 79
Wiconisco H H H 9 120
Williams H H H 9 92
N/A Not Available
1 H – High (3 points)
M – Moderate (2 points)
L – Low (1 point)
2 >8 – High Hazard Potential
5-7 – Moderate Hazard Potential

2.2.10 Human/Animal Diseases and Insect Infestation
Human and Animal diseases are identified in the NFPA 1600 list of possible natural
hazards. Given the amount of human and animal interaction that occurs within Dauphin County
in areas of agriculture, this is a likely hazard that could affect a large portion of the municipalities
should something of this nature occur. Insect infestation, such as Gypsy moths, have been
known to occur in Dauphin County. Due to the amount of agriculture within the County, crops
can be subject to insect infestation as well. Individual instances on how to mitigate for such
disaster are not included in either the original plan or the plan update. Dauphin County has
developed Pandemic Guidelines (May 2009) which addresses this issue on a county basis.
Most municipalities within the County have their own “Continuity of Government” or “Continuity
of Operations” Plans which address this issue specifically for the municipality.
2.2.11 Earthquakes
Any seismic wave which can be read by a seismograph is considered to be an earthquake.
These seismic waves can be the result of either natural or man-made activities. Earthquakes
most commonly occur as a result of a shift or rupture in geologic faults, but sometimes
seismic activity which is interpreted as an earthquake occurs as a result of volcanic activity,
landslides, or mind blasts. The most common naturally occurring type of earthquake, tectonic
earthquakes, occurs along fault lines within the plates that lie under the earth's surface.
In both the recent past and recorded history, there have been earthquakes which have
occurred in neighboring counties and within close proximity to the Dauphin County line. While
earthquakes may be a concern for some areas within Pennsylvania, there have been no earthquakes
reported as having occurred within Dauphin County by the Pennsylvania Geologic
Survey Seismograph located in Middletown. Dauphin County is not located directly over fault
lines; therefore, it is unlikely that any naturally occurring earthquakes would have an epicenter
within the County. It is likely that man-made activities could cause earthquake readings due to
mining or landslides in certain areas within the County.
2.3 VULNERABILITY ASSESSMENT: IDENTIFYING ASSETS
Asset identification is a critical step in the hazard mitigation planning process. Inventorying
existing structures and identifying critical facilities provide insight into the County’s vulnerability
to select hazards and the magnitude of the potential damages of those hazards. As such,
- 40 -

asset identification was conducted as a phased process that involved municipal coordination,
public input, GIS data analysis, Internet research, review of local emergency management
plans, and limited field reconnaissance.
The first task of the asset identification focused on the identification and mapping of
critical facilities throughout the County. Documentation of this critical facilities inventory is
included in the appendices. Critical facilities are structures in which vital community operations
are performed. If these facilities are impacted by a natural hazard, there could be severe
consequences to public health and safety. Therefore, it is imperative that critical facilities be
adequately protected from natural hazards. Critical facilities are not strictly defined by FEMA.
Rather, communities are encouraged to evaluate their own facilities and determine which would
be necessary during an emergency event. As such, critical facilities fall into two general categories:
buildings or locations vital to the hazard response effort (i.e., Emergency
Operations Centers, police, fire and EMS stations, hospitals/mass care
centers, evacuation centers/emergency shelters, communications facilities,
schools, etc.); and
buildings or locations that, if impacted, would create secondary disasters
(i.e., hazardous materials facilities, water/wastewater treatment plants,
etc.).
After the critical facilities were identified and mapped, the focus of the asset identification
shifted to assessing vulnerability on a per-hazard basis. Based on the hazard event profiling
that was described in the previous section, GIS data analysis (via the County’s data) was used
to inventory the total number of structures as well as the critical facilities that are potentially
vulnerable to the identified hazards. As previously mentioned, natural hazards such as drought,
hurricanes/tropical storms, tornadoes, and severe storms are not appropriate to be mapped at
the county level as they are likely to impact the entire County or undefined locations within the
County. As such, the entire County must be considered vulnerable to these hazards. In regard
to the other identified hazards (i.e., dam failure, flooding, land subsidence, landslides, and
wildfires), Table 2-6 lists the total number of vulnerable structures and vulnerable critical facilities
by municipality for the profiled hazard event. Information reported in Table 2-6 was used to
estimate potential losses from the profiled hazard events (see next section).
- 41 -

TABLE 2-6
DAUPHIN COUNTY ASSET VULNERABILITY BY MUNICIPALITY
MUNICIPALITY
TOTAL #
VULNERABLE
STRUCTURES
DAM FAILURE FLOODING LAND SUBSIDENCE LANDSLIDES
VULNERABLE
CRITICAL
FACILITIES
TOTAL #
VULNERABLE
STRUCTURES
VULNERABLE
CRITICAL
FACILITIES
TOTAL #
VULNERABLE
STRUCTURES
VULNERABLE
CRITICAL
FACILITIES
TOTAL #
VULNERABLE
STRUCTURES
VULNERABLE
CRITICAL
FACILITIES
TOTAL #
VULNERABLE
STRUCTURES
WILDFIRES
VULNERABLE
CRITICAL
FACILITIES
Berrysburg Boro 0 0 0 0 0 0 0 0 0 0
Conewago Twp 0 0 7 0 0 0 0 0 423 0
Dauphin Boro 11 0 11 0 0 0 0 0 96 3
Derry Twp 0 0 199 0 5846 11 3 0 947 2
E. Hanover Twp 0 0 51 0 212 0 0 0 215 0
Elizabethville Boro 0 0 5 0 0 0 0 0 49 0
Gratz Boro 0 0 2 0 0 0 0 0 5 0
Halifax Boro 0 0 8 0 0 0 0 0 0 0
Halifax Twp 0 0 60 0 0 0 0 0 185 0
Harrisburg City 1026 2 1299 3 1949 4 0 0 8 0
Highspire Boro 255 0 257 0 0 0 0 0 0 0
Hummelstown Boro 0 0 34 0 1736 4 0 0 0 0
Jackson Twp 0 0 9 0 0 0 1 0 243 0
Jefferson Twp 0 0 12 0 0 0 0 0 211 0
Londonderry Twp 286 0 366 0 0 0 0 0 950 0
Lower Paxton Twp 0 0 244 0 1402 1 0 0 584 1
Lower Swatara Twp 71 0 140 0 435 1 0 0 282 2
Lykens Boro 0 0 388 0 0 0 0 0 68 0
Lykens Twp 0 0 84 0 0 0 0 0 193 1
Middle Paxton Twp 559 3 269 0 0 0 0 0 1414 1
Middletown Boro 105 0 287 0 0 0 0 0 6 0
Mifflin Twp 0 0 2 0 0 0 0 0 107 0
Millersburg Boro 0 0 78 0 0 0 0 0 25 0
Paxtang Boro 0 0 81 0 434 1 0 0 0 0
Penbrook Boro 0 0 0 0 0 0 0 0 0 0
Pillow Boro 0 0 5 0 0 0 0 0 8 0
Reed Twp 12 0 50 0 0 0 0 0 81 1
Royalton Boro 53 0 59 0 0 0 0 0 0 0
Rush Twp 5 0 11 0 0 0 0 0 112 0
S. Hanover Twp 0 0 105 0 125 0 0 0 7 0

TABLE 2-6
DAUPHIN COUNTY ASSET VULNERABILITY BY MUNICIPALITY
MUNICIPALITY
TOTAL #
VULNERABLE
STRUCTURES
DAM FAILURE FLOODING LAND SUBSIDENCE LANDSLIDES
VULNERABLE
CRITICAL
FACILITIES
TOTAL #
VULNERABLE
STRUCTURES
VULNERABLE
CRITICAL
FACILITIES
TOTAL #
VULNERABLE
STRUCTURES
VULNERABLE
CRITICAL
FACILITIES
TOTAL #
VULNERABLE
STRUCTURES
VULNERABLE
CRITICAL
FACILITIES
TOTAL #
VULNERABLE
STRUCTURES
WILDFIRES
VULNERABLE
CRITICAL
FACILITIES
Steelton Boro 170 0 170 0 57 0 0 0 0 0
Susquehanna Twp 377 0 422 0 824 1 0 0 641 0
Swatara Twp 34 0 320 1 2078 3 3 0 104 0
Upper Paxton Twp 0 0 152 0 0 0 0 0 227 0
Washington Twp 0 0 29 0 0 0 0 0 98 0
Wayne Twp 0 0 1 0 0 0 0 0 151 0
W. Hanover Twp 0 0 49 0 212 0 1 0 692 0
Wiconisco Twp 0 0 17 0 0 0 1 0 159 0
Williams Twp 0 0 15 1 0 0 0 0 179 4
Williamstown Boro 0 0 4 0 0 0 0 0 35 0
TOTAL 2964 5 5302 5 15310 27 9 0 8505 15

In addition to critical facilities, Dauphin County contains “at risk” populations that must be
factored into the vulnerability assessment. These include a relatively large population of elderly
residents with limited mobility that are dispersed throughout the County and the inmate populations
of the Dauphin County Prison and Dauphin County Juvenile Detention Facility in Swatara
Township.
In regard to long-term asset identification, coordination with the Tri-County Regional
Planning Commission indicated that Dauphin County is expected to experience continued
growth over the next 15 years. As part of the County Comprehensive Planning process, municipal
population projections to the year 2020 were used to geographically model anticipated
future growth. Analysis of the model product indicated that the majority (89 percent) of the
County’s anticipated future growth is to occur in the southern part of the County as an expansion
of the existing Harrisburg-Hershey suburban population. The remainder (11 percent) of the
County’s anticipated future growth is to occur in the northern part of the County. While any
future development will be susceptible to drought, hurricanes/tropical storms, tornadoes, and
severe storms, proper enforcement of local codes and ordinances should minimize vulnerability
to flooding and other hazards.
2.4 VULNERABILITY ASSESSMENT: ESTIMATING POTENTIAL LOSSES
Estimating potential losses/damages from natural hazard events at the county level can
be a very difficult task to complete with limited data. As such, the Mitigation Steering Committee
relied on the detailed hazard event profile mapping included in the appendices and reported
damage estimates from past hazard events. Damage estimates from past hazard events were
used specifically for those natural hazards that are not applicable to be mapped at the county
level (e.g., droughts, hurricanes/tropical storms, tornadoes, and severe storms). For those
natural hazards that are specific to certain parts of the County (e.g., dam failure, flooding, land
subsidence, landslides, and wildfires), the GIS data analysis that was conducted for the asset
identification and reported in Table 2-6 served as the primary means for estimating potential
losses from the profiled hazard events. In addition, NFIP claims data and 100-year flood loss
estimates calculated for a number of representative floodplain structures identified from
throughout the County were used to supplement the loss estimation for regional flooding. A
summary of the estimated potential losses from the profiled hazard events is provided below.
- 44 -

2.4.1 Potential Dam Failure Losses
Analysis of the DeHart Dam Emergency Action Plan indicated that 169 residences would
be flooded and 10 highway bridges would be blown out by a “Probable Maximum Flood” break
of the DeHart Dam. GIS data analysis conducted for the asset identification (see Table 2-6)
indicated that there are 440 structures in the profiled DeHart Dam failure hazard area. Based
upon windshield survey of the Clarks Creek Valley, it is reasonable to assume that the additional
271 structures are some type of residential accessory structure (i.e., shed, garage, pavilion,
etc.). Based on assessment data of the representative floodplain structures that were identified
from throughout the County, assuming an average residence value of $150,000 appears to be
reasonably representative of the County’s average house value. Similarly, an average residential
accessory structure value of $5,000 appears to be reasonably representative of the County’s
average residential accessory structure value. As such, the following losses can be estimated
for Dauphin County’s DeHart Dam failure hazard.
Residential Accessory = 271 Structures X $5,000 average value per structure X 30% impact* = $406,500
Residential = 169 Structures X $150,000 average value per structure X 30% impact* = $7,605,000
Infrastructure = 10 highway bridges X $250,000 average value per bridge** X 100% impact = $2,500,000
Total = $10,511,500 (does not include content losses)
*30% impact estimate based on location within the impact area but at some distance set back from the stream
channel. The estimate includes some structural damage due to high velocity flood flows.
**Average bridge value based on professional judgment
GIS data analysis conducted for the asset identification indicated that there are approximately
2,524 structures in the profiled Raystown Dam failure hazard area of Dauphin County.
Based upon windshield survey of the geographic area, it is reasonable to assume that 45
percent (1,136) of these structures are residential accessory structures (i.e., sheds, garages,
etc.), 45 percent (1,136) are residences, 8 percent (202) are commercial establishments, and 2
percent (50) are industrial buildings. As such, the following losses can be estimated for Dauphin
County’s Raystown Dam failure hazard.
Residential Accessory = 1,136 Structures X $5,000 average value per structure X 50% impact* = $2,840,000
Residential = 1,136 Structures X $150,000 average value per structure X 50% impact* = $85,200,000
Commercial = 202 Structures X $300,000 average value per structure X 50% impact* = $30,300,000
Industrial = 50 Structures X $1.5 million average value per structure X 50% impact* = $37,500,000
Total = $155,584,000 (does not include content losses)
*50% impact assumes some structural damage due to high velocity flood flows, with many structures in close
proximity to the Susquehanna River.
- 45 -

2.4.2 Potential Drought Losses
While no dollar estimates are available, the 2002 drought event resulted in record low
groundwater levels, record low stream flow levels, record low reservoir/lake levels, and an
unprecedented number of private homeowner well failures in the lower Susquehanna River
basin. Many local farmers suffered crop losses of 70 to 100 percent. In addition, waterdependent
industries, such as nurseries, suffered losses while others had operational concerns
due to the record low stream flow conditions.
2.4.3 Potential Flooding Losses
GIS data analysis conducted for the asset identification indicated that there are approximately
5,302 structures in the 100-year floodplain in Dauphin County. Based upon windshield
survey, assuming that 45 percent (2,386) of these structures are residential accessory structures
(i.e., sheds, garages, etc.), 45 percent (2,386) are residences, 8 percent (424) are commercial
establishments, and 2 percent (106) are industrial buildings, the following losses can be
estimated for Dauphin County’s flooding hazard.
Residential Accessory = 2,386 Structures X $5,000 average value per structure X 10% impact* = $1,193,000
Residential = 2,386 Structures X $150,000 average value per structure X 10% impact* = $35,790,000
Commercial = 424 Structures X $300,000 average value per structure X 10% impact* = $12,720,000
Industrial = 106 Structures X $1.5 million average value per structure X 10% impact* = $15,900,000
Total = $65,603,000 (does not include content losses)
*10% impact is based on average value of flood insurance claims payments through the NFIP and assumes some
structural damage due to high velocity flows and/or depth of floodwaters
In addition to estimating potential future flood losses (see above), NFIP policy claims
data were used to determine recorded flood losses from past flood events. Table 2-7 shows the
total number of flood loss claims, total claims payments, and repetitive loss properties for each
municipality in the County. See the Appendices of this document for mapping of the repetitive
loss structures as well as a classification of the repetitive loss properties by type. A repetitive
loss property is defined as any property for which 2 or more flood insurance claims have been
paid for more than $1,000 in a 10-year period. Information shown in Table 2-7 indicates that
Berrysburg, Elizabethville, Gratz, Penbrook, and Williamstown Boroughs and Jackson, Mifflin,
Rush, and Williams Townships have never submitted flood loss claims to the NFIP. In the
original hazard plan, Table 2-7 indicated that Jefferson and Wiconisco Townships never had
- 46 -

flood loss claims submitted to the NFIP. Since the original plan, each township has had one
claim submitted.
TABLE 2-7
DAUPHIN COUNTY NFIP POLICY CLAIMS DATA BY MUNICIPALITY
MUNICIPALITY
FLOOD
LOSS
CLAIMS
TOTAL
CLAIMS
PAYMENTS
($)
REPETITIVE
LOSS
PROPERTIES
NUMBER OF
CORRESPONDING
NFIP CLAIMS
AVERAGE NUMBER
OF NFIP CLAIMS
PER REPETITIVE
LOSS PROPERTY
Berrysburg Borough 0 0 0 N/A N/A
Conewago Township 3 1,048 0 N/A N/A
Dauphin Borough 60 397,621 12 29 2.4
Derry Township 36 221,250 3 7 2.3
East Hanover Township 9 39,069 1 2 2
Elizabethville Borough 0 0 0 N/A N/A
Gratz Borough 0 0 0 N/A N/A
Halifax Borough 18 21,895 0 N/A N/A
Halifax Township 20 208,501 6 13 2.2
Harrisburg City 1,221 13,871,049 179 378 2.1
Highspire Borough 116 507,784 12 24 2
Hummelstown Borough 39 404,144 5 12 2.4
Jackson Township 0 0 0 N/A N/A
Jefferson Township 1 1,068 0 N/A N/A
Londonderry Township 398 5,745,572 59 135 2.3
Lower Paxton Township 37 70,362 1 3 3
Lower Swatara Township 53 489,970 5 12 2.4
Lykens Borough 28 106,116 1 2 2
Lykens Township 5 15,683 1 3 3
Middle Paxton Township 202 2,018,803 26 63 2.4
Middletown Borough 186 1,727,101 34 69 2
Mifflin Township 0 0 0 N/A N/A
Millersburg Borough 26 100,950 2 4 2
Paxtang Borough 14 46,670 1 5 5
Penbrook Borough 0 0 0 N/A N/A
Pillow Borough 3 6,459 0 N/A N/A
Reed Township 28 220,491 5 13 2.6
Royalton Borough 47 261,341 8 16 2
Rush Township 0 0 0 N/A N/A
South Hanover Township 67 1,592,658 11 33 3
Steelton Borough 107 467,530 18 36 2
Susquehanna Township 352 3,063,555 62 128 2.1
Swatara Township 164 613,050 20 57 2.9
- 47 -

TABLE 2-7
(CONTINUED)
MUNICIPALITY
FLOOD
LOSS
CLAIMS
TOTAL
CLAIMS
PAYMENTS
($)
REPETITIVE
LOSS
PROPERTIES
NUMBER OF
CORRESPONDING
NFIP CLAIMS
AVERAGE NUMBER
OF NFIP CLAIMS
PER REPETITIVE
LOSS PROPERTY
Upper Paxton Township 57 247,004 6 14 1.6
Washington Township 4 23,873 1 3 3
Wayne Township 1 3,381 0 N/A N/A
West Hanover Township 15 138,222 1 4 4
Wiconisco Township 1 9,212 0 N/A N/A
Williams Township 0 0 0 N/A N/A
Williamstown Borough 0 0 0 N/A N/A
TOTAL 3,318 $32,641,432 480 1,065 2.5
Source: NFIP (current as of January 31, 2009) and DCED Repetitive Loss data.
It is important to note that there have been significant changes to Table 2-7 from the
original plan to the current plan update. Analysis of Table 2-7 indicates that there are 480
repetitive loss properties within Dauphin County, in comparison to the 57 properties identified in
the original plan. These properties account for 6.9 percent of the total NFIP flood loss claims to
date. Table 2-7 also indicates that the NFIP has paid over $32 million in flood insurance claims
payments to Dauphin County residents for reported flood losses; this is more than double the
nearly $15 million that was reported in the original hazard plan.
Because these numbers were so drastically different, attention was paid to why these
numbers increased so much in five years. Looking through the properties which are considered
to be repetitive loss that were not previously classified as such showed that the majority of these
properties had an original claim during the ice jam flood event in March 1996. These same
properties were affected during, and filed claims for damages from, the flood event caused by
Hurricane Ivan in September 2004. These two flood events are only eight years apart, meaning
that properties which filed for both events now become classified as repetitive loss for having
two claims filed within ten years. There were an additional 1,161 flood loss claims from January
2004 to January 2009; of those, 929 were NFIP claims.
As previously mentioned, 13 representative floodplain structures (10 residential and 3
commercial/industrial) from throughout the County were used to estimate 100-year flood losses
via FEMA’s Flood Depth-Damage Function (DDF) tables. These 100-year flood losses were
ultimately used to determine the benefit-cost ratios for implementing various property protection
measures (see Section 5.1.3) but can also be used to supplement the regional flood loss estimate.
Flood DDF tables were developed by FEMA to estimate structural damage to buildings,
- 48 -

uilding contents, displacement time, and other losses from flood events. DDF tables list typical
damages to various residential building types based on the depth of flooding in relation to the
structure’s first floor elevation. The DDF tables used to prepare 100-year flood loss estimates
for the 13 Dauphin County representative floodplain structures are shown as Tables 2-8 and
2-9. A summary of the loss estimate results from the 100-year flood event for the 13 representative
floodplain structures are shown in Tables 2-10 and 2-11. The complete loss estimate
results and supporting documentation for these 13 representative floodplain structures are
included in the appendices.
FLOOD
DEPTH
(FEET)
TABLE 2-8
FLOOD DEPTH-DAMAGE FUNCTIONS FOR RESIDENTIAL
REPRESENTATIVE STRUCTURES
RESIDENTIAL BUILDING TYPE: 1- OR 2-STORY WITH BASE-
MENT/CRAWLSPACE
BUILDING DDF
(% DAMAGE
BASED ON BRV)
CONTENTS DDF
(% DAMAGE BASED ON
TOTAL CONTENTS VALUE)
DISPLACEMENT TIME DDF
(BASED ON DAYS OF
LOST SERVICE)
-2 4 6 0
-1 8 12 0
0 11 16.5 38
1 15 22.5 70
2 20 30 110
3 23 34.5 134
4 28 42 174
5 33 49.5 214
6 38 57 254
7 44 66 302
8 49 73.5 342
>8 51 76.5 365
NOTES/LEGEND
Values based on FIA’s Depth-Damage Data Tables in FEMA’s Full Data Benefit-Cost Module for
Riverine Flooding, Version 5.2.3, dated March 10, 1999.
DDFs values for depths 9 feet or greater were estimated from values listed above.
- 49 -

TABLE 2-9
FLOOD DEPTH-DAMAGE FUNCTIONS FOR COMMERCIAL/INDUSTRIAL
REPRESENTATIVE STRUCTURES
FLOOD
DEPTH
(FEET)
BUILDING DDF BY BUILDING TYPE
(% DAMAGE BASED ON BRV)
1- OR 2-
STORY WITH
BASEMENT
(PASB
BUILDING)
2-STORY
WITHOUT
BASEMENT
(SUBWAY
CAFÉ)
INDUSTRIAL
BUILDING
(DAYTON
PARTS)
CONTENTS DDF BY BUILDING TYPE
(% DAMAGE BASED ON
TOTAL CONTENTS VALUE)
1- OR 2-
STORY WITH
BASEMENT
(PASB
BUILDING)
2-STORY
WITHOUT
BASEMENT
(SUBWAY
CAFÉ)
INDUSTRIAL
BUILDING
(DAYTON
PARTS)
FUNCTIONAL DOWNTIME DDF
BY BUILDING TYPE
(BASED ON DAYS OF LOST SERVICE)
1- OR 2-
STORY WITH
BASEMENT
(PASB
BUILDING)
2-STORY
WITHOUT
BASEMENT
(SUBWAY
CAFÉ)
INDUSTRIAL
BUILDING
(DAYTON
PARTS)
-2 4 4 0 6 0 0 4 0 0
-1 8 0 0 12 0 0 8 0 0
0 11 5 2.5 16.5 7.5 3.75 11 5 1.25
1 15 9 4.5 22.5 13.5 6.75 15 9 2.25
2 20 13 6.5 30 19.5 9.75 20 13 3.25
3 23 18 9 34.5 27 13.5 23 18 4.5
4 28 20 10 42 30 15 28 20 5
5 33 22 11 49.5 33 16.5 30 22 5.5
6 38 24 12 57 36 18 30 24 6
7 44 26 13 66 39 19.5 30 26 6.5
8 49 29 14.5 73.5 43.5 21.75 30 29 7.25
>8 51 33 16.5 76.5 49.5 24.75 30 30 8.25
NOTES/LEGEND
Values based on FIA’s Depth-Damage Data Tables in FEMA’s Full Data Benefit-Cost Module for Riverine Flooding, Version 5.2.3, dated
March 10, 1999.
DDFs for Industrial Buildings based on 2-story structure with basement; building and contents DDFs reduced by 50% to account for commercial
building with masonry construction.
DDFs values for depths 9 feet or greater were estimated from values listed above.

TABLE 2-10
SUMMARY OF 100-YEAR FLOOD LOSS ESTIMATE RESULTS FOR
RESIDENTIAL REPRESENTATIVE STRUCTURES
FLOODPLAIN
REPRESENTATIVE STRUCTURE
BREAKDOWN OF TYPICAL
100-YEAR FLOOD LOSSES ($)
BUILDING CONTENTS
DISPLACE-
MENT
TOTAL
Fishing Creek Valley $15,136 $6,811 $7,749 $29,696
Lawton Branch of Spring Creek $17,058 $7,676 $5,471 $30,205
Susquehanna River - Shipoke Duplex $127,964 $57,584 $62,989 $248,537
Stony Creek - Middle Paxton Township $20,661 $9,297 $13,926 $43,884
Susquehanna River - Middle Paxton $33,256 $14,965 $13,683 $61,904
Swatara Creek - Middletown Borough $14,000 $6,300 $3,903 $24,203
Wiconisco Creek - Millersburg Area $28,327 $12,747 $10,346 $51,420
Swatara Creek - South Hanover
Township
$55,864 $25,139 $28,777 $109,780
Swatara Creek - Royalton Borough $34,336 $15,451 $14,451 $64,238
Manada Creek $6,199 $2,790 $3,017 $12,006
TOTAL $352,801 $158,760 $164,312 $675,873
TABLE 2-11
SUMMARY OF 100-YEAR FLOOD LOSS ESTIMATE RESULTS FOR
COMMERCIAL/INDUSTRIAL REPRESENTATIVE STRUCTURES
FLOODPLAIN
REPRESENTATIVE STRUC-
TURE
Susquehanna River - PSAB
Building
BUILDING CONTENTS
BREAKDOWN OF TYPICAL
100-YEAR FLOOD LOSSES ($)
LOSS OF FUNC-
TION
TOTAL
$461,531 $692,296 $238,356 $1,392,183
Paxton Creek - Subway Café $47,031 $70,540 $1,648 $119,225
Paxton Creek - Dayton Parts $572,313 $1,287,704 $156,636 $2,016,654
TOTAL $1,080,874 $2,050,547 $396,641 $3,528,062
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2.4.4 Potential Hurricane/Tropical Storm Losses
Damage estimates from the 1972 Tropical Storm Agnes event were reported at
$183,787,000 (1972) for Dauphin County. This included residential, commercial, industrial, and
infrastructure damages.
2.4.5 Potential Land Subsidence Losses
GIS data analysis conducted for the asset identification indicated that there are approximately
15,310 structures in the profiled land subsidence hazard area of Dauphin County.
Assuming a worst-case scenario that 10 percent of these structures (of which 40 percent are
residential accessory, 40 percent are residences, 15 percent are commercial, and 5 percent are
industrial [based upon windshield survey of the profiled land subsidence hazard area]) would be
impacted by subsidence events, the following losses can be estimated for Dauphin County’s
subsidence hazard.
Residential Accessory=612 Structures X $5,000 average value per structure X 50% impact* = $1,530,000
Residential = 612 Structures X $150,000 average value per structure X 10% impact* = $9,180,000
Commercial = 230 Structures X $300,000 average value per structure X 5% impact* = $3,450,000
Industrial = 77 Structures X $1.5 million average value per structure X 1% impact* = $1,155,000
Total = $15,315,000 (does not include content losses)
*% impact is based upon the average cost to structurally mitigate a subsidence feature in relation to the average
value per structure
2.4.6 Potential Landslide Losses
GIS data analysis conducted for the asset identification indicated that there are approximately
nine structures in the profiled landslide hazard area of Dauphin County. Assuming a
worst-case scenario of two residences and two residential accessory structures impacted by a
landslide event, the following losses can be estimated for Dauphin County’s landslide hazard.
Residential Accessory = 2 Structures X $5,000 average value per structure X 100% impact* = $10,000
Residential = 2 Structures X $150,000 average value per structure X 100% impact* = $300,000
Total = $310,000 (does not include content losses)
*100% impact assumes total loss of structure due to landslide event
- 52 -

2.4.7 Potential Severe Storm Losses
Damage estimates from the July 1995 severe thunderstorm event were reported at $1
million (1995) for Dauphin County. This included primarily residential and infrastructure (i.e.,
utility line) damages.
2.4.8 Potential Tornado Losses
Damage estimates from the April 1977 F2 tornado event were reported at $2.5 million
(1977) for Dauphin County. This included residential, commercial, industrial, and infrastructure
damages.
2.4.9 Potential Wildfire Losses
GIS data analysis conducted for the asset identification indicated that there are approximately
8,505 vulnerable structures in the profiled wildfire hazard area of Dauphin County.
Based upon windshield survey of the geographic area, it is reasonable to assume that the vast
majority of these vulnerable structures consists of residences and residential accessory structures.
As previously mentioned, the largest wildfire to occur in Dauphin County in the past 25
years resulted in approximately 200 acres of burned area. Using this largest recorded event,
and assuming a worst-case scenario of one burned residence and one burned residential
accessory structure per acre of burned area, the following losses can be estimated for Dauphin
County’s wildfire hazard.
Residential Accessory=200 Structures X $5,000 average value per structure X 100% impact*=$1,000,000
Residential = 200 Structures X $150,000 average value per structure X 100% impact* = $30,000,000
Total = $31,000,000 (does not include content losses)
*100% impact assumes total loss of structure due to wildfire event
2.5 VULNERABILITY ASSESSMENT: ANALYZING DEVELOPMENT TRENDS
Dauphin County is centrally located in the state and consists of a diverse mixture of land
uses. The most prominent feature of Dauphin County is the City of Harrisburg, which serves as
the State Capitol. Harrisburg is located in the southern part of the County adjacent to the
Susquehanna River. Many of the townships and outlying areas surrounding Harrisburg have
- 53 -

and are continuing to experience extensive suburban development. This suburban development
consists of residential subdivisions, commercial complexes, and industrial parks.
Just ten miles east of Harrisburg, in Derry Township, is the Village of Hershey. Hershey
is internationally famous for its production of Hershey chocolate candies and the associated
Hershey Amusement Park. Hershey and its surrounding area have and are continuing to be
developed with residential subdivisions, commercial complexes, and industrial facilities similar
to that of the townships and outlying areas surrounding the City of Harrisburg. Combined, this
Harrisburg-Hershey area is considered to be the most developed part of the County. As previously
mentioned, the Dauphin County Comprehensive Plan identified the southern portion of the
County (which encompasses the Harrisburg-Hershey area) as the anticipated location for the
majority (89 percent) of the County’s future growth.
Land use and development trends in the northern part of the County are very different
than the southern part of the County. Outside the small boroughs of Dauphin, Halifax, Millersburg,
Elizabethville, Lykens, Williamstown, Berrysburg, Pillow, and Gratz, the majority of the
northern part of the County is primarily undeveloped agricultural land and forested areas. The
bulk of the forested area is situated on the sides of mountains with the valleys comprising most
of the agricultural land. Development in the northern part of the County consists primarily of
scattered residences on large lots. Commercial and industrial land uses are limited to the
boroughs and immediate areas. As previously mentioned, the Dauphin County Comprehensive
Plan indicated that the northern part of the County is anticipated to account for only 11 percent
of the County’s future growth.
In regard to assessing the vulnerability of the County’s future development to natural
hazards, several generalizations can be made. Natural hazards such as drought, hurricanes/
tropical storms, severe storms, and tornadoes have the potential to impact all future development
as they are not defined to specific locations of the County. As evidenced by the regional
hazard event profile mapping included in the Appendices, future development in the northern
part of the County would generally be more susceptible to wildfires, landslides, and flooding,
depending on the location. In addition, any future development that occurs on the south side of
Route 325 in Clarks Valley west of the DeHart Dam has the potential to be impacted by a failure
of the dam. Similarly, future development in the southern part of the County would generally be
more susceptible to land subsidence and flooding, depending on the location.
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2.6 MULTI-JURISDICTIONAL RISK ASSESSMENT
As previously mentioned, natural hazards such as drought, hurricanes/tropical storms,
severe storms, and tornadoes are not specific to certain parts of the County but rather impact
the entire County or any location in the County. Conversely, natural hazards such as dam
failures, flooding, land subsidence, landslides, and wildfires are specific to certain locations and
jurisdictions within the County as shown on the regional hazard event profile mapping included
in the appendices and described in the preceding text.
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3.0 HAZARD MITIGATION GOALS

3.0 HAZARD MITIGATION GOALS
The Mitigation Steering Committee re-examined the project-planning goals as part of this
updated Hazard Mitigation Plan. The identification and prioritization of project-planning goals
were based on the findings of the hazard vulnerability assessment in 2005, were reexamined
again in 2009, and were specifically focused on the County’s vulnerability to the profiled natural
hazard events and the potential severity (i.e., frequency and magnitude) of those hazard events.
As such, these project-planning goals represent the County’s updated vision for minimizing
damages caused by flooding and other natural hazards.
To prioritize the goals, the individual Mitigation Steering Committee members assigned a
rank value to each goal based on a scale of 1 to 5, with 1 representing low-priority and 5 representing
high-priority. These individual rank values were then tallied for each goal and divided by
the total number of responses to come up with a composite prioritization ranking for each goal.
These composite prioritization rankings were used to classify the goals as high-, medium-, and
low-priority. The project-planning goals identified for the County are listed below (in random
order) according to their calculated composite prioritization.
3.1 HIGH-PRIORITY HAZARD MITIGATION GOALS
Ensure that existing drainage systems (pipes, culverts, channels) are adequate
and functioning properly.
Ensure that local ordinances are consistent with FEMA and PA DCED
guidelines and are properly enforced.
Preserve areas where natural hazard potential is high (i.e., steeply sloping
areas, sinkhole areas, floodplains, wetlands, etc.).
Provide residents with adequate warning of potential floods and other meteorological
events.
Ensure that emergency response services and critical facilities functions
are not interrupted by natural hazards.
Provide safe and efficient evacuation routes during floods and other natural
hazards.
Provide adequate shelters during hazard events.
Minimize future damage due to flooding of the Susquehanna River and its
tributaries.
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Provide adequate communication systems for emergency management
agencies and emergency response units.
Increase the length of stream reaches mapped on FIRM maps and/or increase
the occurrence of flood elevation data where this future mapping
would be beneficial.
3.2 MEDIUM-PRIORITY HAZARD MITIGATION GOALS
Reduce impacts related to flash flooding and stormwater problems.
Reduce impacts from severe storms and/or improve response procedures.
Investigate structural solutions to natural hazards.
Regulate construction/development in the County to prevent increases in
runoff and subsequent increases in flood flows.
Ensure that new construction is resistant to natural hazards.
Ensure that high-risk, pre-FIRM residential structures do not get repeatedly
flooded by using retrofitting techniques to reduce the flood risk to the
properties.
Reduce the impact of flooding on commercial structures through retrofitting
techniques.
Investigate retrofitting alternatives to reduce impacts from other natural
hazards.
Protect existing natural resources and open space, including parks and
wetlands, within the floodplain.
Restore degraded natural resources and open space to improve their
flood control function.
Ensure the adequacy of erosion and sedimentation control practices
throughout the County.
Ensure that all residents and business owners are aware of the potential
hazards associated with their environment and the ways they can protect
themselves.
Ensure that property owners and potential property owners are aware of
the availability and benefits of obtaining federal flood insurance.
Ensure that local officials and EMA staff are well trained regarding natural
hazards and appropriate prevention and mitigation activities.
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Develop citizen information on natural, technological, and man-made disaster
response.
3.3 LOW-PRIORITY HAZARD MITIGATION GOALS
Reduce threats related to wildfires.
Reduce threats related to hurricanes.
Minimize crop damage due to drought situations.
Reduce threats related to landslides.
Evaluate the potential for improving building and infrastructure resistance
to land subsidence.
Improve the participation rate in federal flood insurance through education.
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4.0 CAPABILITY ASSESSMENT

4.0 CAPABILITY ASSESSMENT
4.1 INTRODUCTION
A capability assessment involves an evaluation of the County in regard to its governmental
structure, political framework, legal jurisdiction, fiscal status, policies and programs,
regulations and ordinances, and resource availability. These factors are evaluated with respect
to their strengths and weaknesses in preparing for, responding to and mitigating the effects of
the profiled natural hazards. By doing so, the Mitigation Steering Committee can draw reasonable
conclusions as to the relative appropriateness of various hazard mitigation action items that
may be identified as part of the hazard mitigation strategy. As such, the capability assessment
plays an important role in the hazard mitigation planning process. The capability assessment
was originally developed during the original hazard plan process, but it has been updated to
reflect changes within the County and each municipality that have occurred in the last five
years.
Within Pennsylvania, no county-level capability assessment would be complete without
considering the constituent municipalities. Local municipalities have their own governing body,
enforce their own rules and regulations, purchase their own equipment, maintain their own
infrastructure, and manage their own resources. In many ways, the County is only as good as
the capabilities of its constituent municipalities. As such, this capability assessment does not
consider Dauphin County as a lone entity, but evaluates it in light of the various characteristics
and differences of and between its 40 constituent municipalities.
4.2 INSTITUTIONAL CAPABILITY
Dauphin County’s 40 constituent municipalities include 1 city, 16 boroughs, and 23
townships. Each of these municipalities carries out their daily operations and provides various
community services according to their local needs and limitations. Some of these municipalities
have formed cooperative agreements and work jointly with their neighboring municipalities to
provide such services as police protection, fire and emergency response, solid waste disposal,
recreational opportunities, wastewater treatment, infrastructure maintenance, and water supply
management, while others choose to operate on their own. They vary in staff size, resource
availability, fiscal status, service provision, constituent population, overall size, and vulnerability
to the profiled hazards. In fact, the Capability Assessment Matrix included in the Appendices
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indicates that 13 of the 40 municipalities do not have a local planning commission. As such, it is
easy to see why the County’s capabilities to deal with hazards are a reflection of the local
municipalities.
Generally speaking, the municipalities in the northern mountainous part of the County
tend to have fewer residents (according to the County’s Comprehensive Plan, the northern
planning section consists of 19 municipalities, but only accounts for about 10% of the County’s
total population), less staff, and, by default, a more limited supply of available resources than
those municipalities in the more urbanized southern part of the County. This is not to say,
however, that hazard mitigation is not an important factor in the northern part of the County. It
simply may require a more unified or coordinated approach and/or more efficient utilization of a
limited supply of available resources (e.g., financial, technical, and human). For example, Reed
Township in the northern part of the County, with its resident population of 182 persons, would
not be expected, nor would it be appropriate, to engage in hazard mitigation activities on a scale
similar to that of Harrisburg City, with its resident population of 48,950 persons. Rather, Reed
Township would be expected to engage in hazard mitigation activities according to its local
needs and available resources, which may prove to be as valuable to its residents as that of
some other municipality’s hazard mitigation activities.
In addition to the institutional capability of the municipal government structure described
above, the County itself is capable of engaging in hazard mitigation activities. The County has
its own staff, resources, budget, equipment, and objectives, which may or may not be similar to
those of its constituent municipalities. As such, the County itself has its own capabilities to
mitigate the profiled hazards. When partnered with the local municipalities, the state, the
federal government, local COGs, watershed groups, environmental groups, or some other
entity, the results could be limitless.
4.3 LEGAL CAPABILITY
Within Pennsylvania, municipalities have the authority to govern more restrictively than
state and County minimum requirements as long as they are in compliance with all criteria
established in the Pennsylvania Municipalities Planning Code and their respective municipal
codes. Municipalities can, and typically do, develop their own policies and programs and
implement their own rules and regulations to protect and serve their local residents. Local
policies and programs are typically identified in a comprehensive plan, implemented via local
ordinance, and enforced through the governmental body or its appointee.
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Municipalities regulate development via the adoption and enforcement of zoning, subdivision
and land development, building code, building permit, floodplain management, and/or
stormwater management ordinances. Within the development, adoption, and enforcement of
these ordinances, there is an opportunity for hazard mitigation in the form of preventive
measures. Most notably is the municipal adoption of NFIP and Pennsylvania Floodplain Management
Act (Act 166 of 1978) minimum floodplain management criteria. A municipality must
adopt and enforce these minimum criteria to be eligible for participation in the NFIP. As such,
municipalities have the option of adopting a single-purpose ordinance or incorporating these
provisions into their zoning, subdivision and land development, or building code ordinances,
thereby mitigating the potential impacts of local flooding in a preventive manner.
The Capability Assessment Matrix included in the Appendices has been prepared to
document the County’s and its constituent municipalities’ existing legal capabilities to mitigate
the profiled hazards in a preventive manner. This matrix identifies the municipalities’ existing
planning documents and makes note of their hazard mitigation potential. The table has been
updated to show the most current date of the planning documents. Those which have been
updated since the original Hazard Mitigation Plan are highlighted. Preventive measure hazard
mitigation recommendations are based on the information contained in this matrix.
4.4 FISCAL CAPABILITY
Finances can be an important factor in the capability of any jurisdiction to implement
hazard mitigation activities. Every jurisdiction, including those in Dauphin County, must operate
within the constraints of limited financial resources. As such, the key factor in determining fiscal
capability is to analyze how tight these constraints are. This could involve a detailed auditing
process to tally all revenues and expenditures, or could involve an assessment of existing
financial ratings as identified and reported by the PA DCED. For the purposes of this planning
program, the Mitigation Steering Committee elected to use the existing financial ratings reported
by the PA DCED as a base indicator of fiscal capability at the municipal level.
The Pennsylvania Municipalities Financial Recovery Act (Act 47 of 1987) identified
fiscally distressed municipalities based on established criteria, and authorized the PA DCED to
assist in developing financial recovery plans in these areas. Analysis of the Act 47 fiscally
distressed municipality list indicated that none of Dauphin County’s municipalities were identified
as being fiscally distressed at either the time of the original plan or the plan update according
to the established rating criteria. However, in accordance with Section 1303 of the Pennsyl-
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vania Job Enhancement Act (73 P.S. Section 400.1303) the Pennsylvania State Data Center
designated several Dauphin County municipalities as distressed communities based on their
ability to meet at least three of the following five criteria. This list of communities is used by the
DCED for loan eligibility.
Twenty percent or more of the population with incomes below the poverty
level as reported in the latest decennial census.
Fifteen percent or more of the labor force is unemployed as reported in
the census or as reported in a survey done by the municipality.
Five percent or more loss of population as reported in the census.
Significant business vacancy rate within the area, either in gross footage
or acreage or in the number of business or industrial buildings.
Significant reduction in employment.
Those Dauphin County municipalities that were designated as distressed communities under
the Job Enhancement Act include:
Berrysburg Borough,
Elizabethville Borough,
Gratz Borough,
Halifax Borough,
Halifax Township,
Harrisburg City,
Highspire Borough,
Jackson Township,
Jefferson Township,
Lower Paxton Township,
Lykens Township,
Middletown Borough,
Mifflin Township,
Pillow Borough,
Reed Township,
Swatara Township,
Washington Township,
Wayne Township,
Williams Township, and
Williamstown Borough.
While this distressed community designation may provide some insight into the fiscal
capability of the subject municipalities, it most certainly does not preclude these municipalities
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from participating in hazard mitigation activities. Cooperative arrangements, coordinated efforts,
and resource efficiency may serve as effective avenues for overcoming fiscal constraints and
accomplishing hazard mitigation objectives at the local level.
It is important to remember that finances are not the only factor in determining hazard
mitigation capability. In addition, there are numerous partnering opportunities and grant programs
available to assist in offsetting the expenses of local hazard mitigation efforts. Thanks to
the Pennsylvania Department of Environmental Protection’s (PA DEP) Growing Greener grant
program there are numerous watershed associations available for municipalities to partner with
to accomplish hazard mitigation activities. Within Dauphin County, watershed associations
have been formed for:
Paxton Creek,
Powells and Armstrong Creeks,
Wiconisco Creek,
Swatara Creek,
Conewago Creek,
Mahantango Creek, and
Manada Creek.
In addition, there are partnering opportunities at the local level with the SRBC, DEMA,
TCRPC, and the Northern Dauphin County Boroughs Council-of-Governments. Grant programs
that may be utilized to accomplish hazard mitigation objectives include the PA DCED’s Land
Use Planning and Technical Assistance (LUPTAP), Shared Municipal Services (SMS), Community
Revitalization (CR), and Floodplain Land Use Assistance Programs; the PA DEP’s Growing
Greener, Act 167 Stormwater Management, Source Water Protection, and Flood Protection
Programs; the PA DCNR’s Community Conservation Partnership Program; PEMA’s Pre-
Disaster Mitigation (PDM) Grant and Flood Mitigation Assistance Programs (FMAP); the Pennsylvania
Infrastructure Investment Authority’s (PennVEST) low interest loan and grant program;
and various other federal and state programs.
4.5 POLITICAL CAPABILITY
Political capability refers to a jurisdiction’s incentive or willingness to accomplish hazard
mitigation objectives. Local decision makers may not rank hazard mitigation as a high priority
task if there hasn’t been a disaster in recent history or if there are other more immediate political
concerns. Unfortunately, there is no better way to get people thinking about hazard mitigation
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than to have a disaster occur. Responding to and recovering from a disaster event can exhaust
local resources, thereby elevating hazard mitigation to the forefront of political agendas. This
reactionary effort, while somewhat nominal in value during the aftermath of a disaster event, can
go a long way in preparing for and mitigating future events.
Within Dauphin County, many long-term residents and business owners remember the
devastation that was caused by Tropical Storm Agnes in June 1972. The Agnes flood event is
the flood of record for the Susquehanna River in Dauphin County. If not the Agnes event, most
Dauphin County residents can recall the January 1996 ice jam flood, which washed away a
section of the Walnut Street Bridge. Given this relatively recent flood event and the severity of
the 1972 Agnes event, the political capability of Dauphin County should not be an issue when
planning for and implementing local hazard mitigation activities, as long as the activities are
generally accepted by the public and perceived to be relatively cost-beneficial.
4.6 TECHNICAL CAPABILITY
Technical capability refers to a jurisdiction’s availability of resources (other than financial)
and knowledge/skill level to accomplish hazard mitigation objectives. Necessary resources
typically include personnel (paid or volunteer), equipment/machinery, and materials/supplies.
Without the necessary resources, all other measurements of a jurisdiction’s capability (i.e.,
institutional, legal, fiscal, and political) to accomplish hazard mitigation are moot. Conversely,
resource availability is moot if the jurisdiction does not have the knowledge/skill level necessary
to effectively accomplish the designated hazard mitigation objective. As such, technical capability
(i.e., resource availability and knowledge/skill level) is an important factor when analyzing a
jurisdiction’s ability to accomplish hazard mitigation objectives.
Within Dauphin County, technical capability varies widely between the municipalities.
Even neighboring municipalities may exhibit extreme variations in technical capability. Generally
speaking, the more financial resources a municipality has, the more technically capable it will
probably be from a resource availability perspective. This is not necessarily the case, however,
when analyzing technical capability from a knowledge/skill level perspective. As such, technical
capability must be analyzed by each individual municipality prior to implementing any hazard
mitigation activities. It is important to note, however, that much like fiscal capability, shortfalls in
technical capability may be overcome by cooperative arrangements, coordinated efforts, and/or
resource efficiency.
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5.0 HAZARD MITIGATION STRATEGY

5.0 HAZARD MITIGATION STRATEGY
5.1 IDENTIFICATION AND ANALYSIS OF HAZARD MITIGATION MEASURES
5.1.1 Preventive Measures
Preventive measures are designed to minimize the potential development of new natural
hazard problems and are intended to keep existing natural hazard problems from becoming
worse. They ensure that future land development projects do not increase local and/or regional
natural hazard damage potentials. Preventive measures are usually administered by local
building, zoning, planning, and/or code enforcement officials and typically include the following:
land use planning/zoning efforts;
subdivision and land development ordinances;
building codes;
floodplain development regulations;
stormwater management;
operations and maintenance (O&M) procedures;
subsurface investigation requirements; and
public education programs.
Implementation of preventive measures of this nature will work towards the fulfillment of the
following project-planning goals as identified by the Mitigation Steering Committee.
Ensure that local building codes/ordinances are consistent with FEMA
and PA DCED guidelines and are properly enforced.
Minimize future damage due to flooding of the Susquehanna River and its
tributaries.
Regulate construction/development in the County to prevent increases in
runoff and subsequent increases in floodflows.
Ensure that new construction is resistant to natural hazards.
Evaluate the potential for improving building and infrastructure resistance
to tornadoes.
Evaluate the potential for improving building and infrastructure resistance
to land subsidence.
Reduce threats related to wildfires.
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Reduce threats related to landslides.
Reduce impacts related to flash flooding and stormwater problems.
5.1.1.1 Land Use Planning/Zoning Efforts
Comprehensive plans and other similar land use plans define how and where a community,
region, or area should be developed. Similarly, zoning ordinances regulate development
by dividing a community or region into zones or districts and establishing specific development
criteria for each zone or district. As such, comprehensive/land use plans and zoning ordinances
can be developed to include provisions for the area’s known natural hazards. For example, a
comprehensive/land use plan can include an assessment and associated mapping of the
respective area’s vulnerability to location-specific hazards (e.g., dam failure, flooding, landslides,
land subsidence, and wildfires) and make appropriate recommendations for the planned
use of these known hazard areas. Similarly, a zoning ordinance can include separate zones or
districts with appropriate development criteria for these known hazard areas. As such, the
Mitigation Steering Committee identified the following Preventive Measure (PM) Hazard Mitigation
Measures to be implemented within the County.
PM-1:
PM-2:
PM-3:
Develop a new Comprehensive Plan or amend an existing Comprehensive
Plan to include an assessment and associated mapping
of the municipality’s vulnerability to location-specific hazards
and appropriate recommendations for the use of these hazard areas.
Develop a new Zoning Ordinance or revise an existing Zoning Ordinance
to include separate zones or districts with appropriate development
criteria for known hazard areas.
Make available for municipal use the digital natural hazard mapping
files that were developed as part of this hazard vulnerability
assessment and mitigation planning effort.
5.1.1.2 Subdivision and Land Development Ordinances
Subdivision and land development ordinances regulate how land can be subdivided into
individual lots and establish certain standards/criteria for the location and construction of buildings
and associated infrastructure (i.e., roads, sidewalks, utility lines, stormwater management
facilities, etc.). As such, local subdivision and land development ordinances can be written to
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include municipality-specific, hazard mitigation-related development criteria for the location and
construction of buildings and other infrastructure in known hazard areas in an effort to avoid
future damages and minimize existing problems. Examples of some hazard mitigation-related
development criteria include watershed-specific stormwater management regulations (see
PM-7), land use-specific erosion and sedimentation control requirements (see NR-7), hazardspecific
building and infrastructure location limitations (see PM-12), and a requirement to
incorporate various pre-defined, municipality-specific hazard mitigation/prevention measures
into all development plans. Along these same lines, the mandatory use of conservation subdivision
design principles could also be employed to minimize/mitigate the potential impacts of
natural hazards. Conservation subdivision design principles involve clustering homes/development
in a proposed subdivision to avoid known hazard areas (i.e., steep slopes, floodplains,
etc.) and environmentally sensitive resources (i.e., wetlands, critical wildlife habitats, etc.),
thereby developing the most appropriate land while permanently establishing a network of
protected open spaces (additional information on these “Growing Smarter” land use concepts is
included in the appendices for reference purposes). As such, the Mitigation Steering Committee
identified the following Preventive Measure Hazard Mitigation Measure to be implemented
within the County.
PM-4:
Develop a new Subdivision and Land Development Ordinance or
revise an existing Subdivision and Land Development Ordinance
to include municipality-specific, hazard mitigation-related development
criteria and/or provisions for the mandatory use of conservation
subdivision design principles in order to regulate the location
and construction of buildings and other infrastructure in
known hazard areas.
5.1.1.3 Building Codes
Building codes regulate the construction, renovation, and alteration of new and existing
structures by establishing minimum building standards and providing for routine inspections by a
certified building code inspector. As such, local building codes can include specific standards
for hazard-resistant construction. Examples of some hazard mitigation-related building standards
include requiring the use of fireproof/resistant building materials, specifying particular
construction practices to promote wind resistance, specifying the use of waterproof/resistant
building materials in known flood hazard areas, and requiring certain foundation and structure
anchoring specifications in known floodwater velocity areas. In Pennsylvania, a state law was
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passed in 1999 establishing a statewide Uniform Construction Code (UCC). The law establishes
the BOCA National Building Code (and its successor codes) as the minimum standard for the
construction, alteration, and repair of commercial and residential structures throughout the
Commonwealth. While the UCC includes some general hazard mitigation-related building
standards, some hazard-prone municipalities may find it appropriate to adopt more stringent
building standards to ensure hazard resistant construction. As such, the Mitigation Steering
Committee recognized the implementation of the UCC and the potential local adoption of more
stringent standards for hazard resistant construction as a Preventive Measure Hazard Mitigation
Measure for the County.
PM-5:
Implement the minimum building standards of the Pennsylvania
Uniform Construction Code and/or consider the potential adoption
of more stringent building standards to ensure hazard-resistant
construction.
5.1.1.4 Floodplain Development Regulations
Floodplain development regulations establish regulatory criteria for the construction and/
or alteration of buildings and other development located in the 100-year floodplain in an effort to
minimize potential flood-related damages and ensure that new development does not exacerbate
local flood hazards. Municipalities that participate in the NFIP must adopt and enforce
floodplain development regulations that meet or exceed minimum NFIP standards and requirements.
NFIP floodplain development regulations prohibit obstruction of the regulatory floodway
and require new buildings being constructed in the 100-year floodplain to be protected from
damage by the base flood (i.e., 100-year or 1% annual chance flood). NFIP floodplain development
regulations are intended to prevent loss of life and property as well as economic and
social hardships that result from flooding. In addition to these minimum federal requirements,
the Pennsylvania Floodplain Management Act (Act 166 of 1978) established more restrictive
floodplain development regulations. Act 166 discourages the construction of hospitals, nursing
homes, jails, and mobile home parks in the floodplain and prohibits development that “may
endanger human life” in the regulatory floodway. Such development includes that which would
require the production or storage of hazardous and radioactive materials. Floodplain development
regulations can be incorporated into a municipality’s existing codes/ordinances or can be
adopted as a separate, stand-alone ordinance. As such, the Mitigation Steering Committee
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identified the following Preventive Measure Hazard Mitigation Measure to be implemented
within the County.
PM-6:
Ensure municipal compliance with NFIP and PA Act 166 floodplain
development regulations and/or encourage more restrictive requirements,
as appropriate.
5.1.1.5 Stormwater Management
Effective management of stormwater runoff from developed areas can go a long way in
minimizing local and regional drainage problems and associated flooding hazards. In addition,
stormwater management practices that promote infiltration work towards the minimization of
drought impacts by contributing to the base flow of local streams and watercourses. Stormwater
management regulations, which are usually incorporated into a municipality’s subdivision
and land development ordinance, require developers to construct on-site stormwater management
facilities that will effectively collect, convey, and store surface water runoff. Within Dauphin
County, the Conservation District (DCCD) is very active in the completion of watershedspecific
stormwater management plans in accordance with Pennsylvania’s Stormwater Management
Act (Act 167 of 1968). These watershed-specific Act 167 Stormwater Management
Plans establish stormwater management criteria based on the hydrologic and hydraulic characteristics
of the subject watershed. Within six months of County adoption of an Act 167 Stormwater
Management Plan, the respective watershed municipalities must adopt and enforce the
stormwater management ordinance included in the Plan. As such, the Mitigation Steering
Committee recognized the DCCD’s active participation in the Act 167 Stormwater Management
Planning Program and identified municipal compliance with their respective watershed stormwater
management plans as a Preventive Measure Hazard Mitigation Measure for the County.
PM-7: Ensure municipal compliance with local watershed-specific Act
167 Stormwater Management Plans and Ordinances.
5.1.1.6 Operations and Maintenance Procedures
Effective implementation of appropriate O&M procedures at the DeHart Dam are fundamental
to the prevention of a potential failure. Routine inspections and regular maintenance
(standard O&M procedures for a municipal water supply dam) are the most critical measures
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that can be taken to prevent a dam failure. As such, the Mitigation Steering Committee recognized
the City of Harrisburg’s existing O&M procedures at the DeHart Dam and identified the
continued implementation of these O&M procedures as a Preventive Measure Hazard Mitigation
Measure for the County.
PM-8:
Ensure continued implementation of appropriate operations and
maintenance procedures (routine inspections and regular maintenance)
at the DeHart Dam in an effort to prevent a potential failure.
5.1.1.7 Subsurface Investigation Requirements
Subsurface investigation requirements for new subdivision and land development
projects in known land subsidence hazard areas can prevent costly, and sometimes irreparable,
structural damage caused by sinkholes. Subsurface investigation requirements in the form of
borings, geophysical surveys, and/or studies conducted by a registered Professional Geologist
can be incorporated into a municipality’s existing zoning and/or subdivision and land development
ordinances or can be adopted as a separate, stand-alone ordinance. While existing
structures would continue to be susceptible, local implementation of this type of ordinance
provision would successfully eliminate new construction from being damaged by the land
subsidence hazard. As such, the Mitigation Steering Committee identified the following Preventive
Measure Hazard Mitigation Measure to be implemented within the County.
PM-9:
Revise existing zoning and/or subdivision and land development
ordinances or adopt a separate, stand-alone ordinance to require
the completion of subsurface investigations (i.e., borings, geophysical
surveys, and/or studies by a registered Professional Geologist)
for all new subdivision and land development projects in
known land subsidence hazard areas.
5.1.1.8 Public Education Programs
Public education programs can be implemented as a preventive hazard mitigation
measure when dealing with hazards that have the potential to be induced by human activity.
Public education can counter the viability of certain hazards and diminish their frequency of
occurrence. A good example of a public education program that has successfully decreased
the number of occurrences of human-induced incidents is the U.S. Forest Service’s use of
Smokey the Bear. Since the development of Smokey the Bear, the number of wildfires caused
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y children playing with matches has decreased dramatically. Within Dauphin County, the only
natural hazard that has the potential to be human-induced is wildfire. As such, the Mitigation
Steering Committee identified the implementation of a public education program aimed at
minimizing human-induced wildfires as a Preventive Measure Hazard Mitigation Measure to be
implemented at the County level. This public education program is to be a joint effort between
DEMA and the PA DCNR Bureau of Forestry and is to consist of the development and mass
distribution of an informative brochure and training for local officials on Pennsylvania’s Firewise
Communities Program. In addition, the Mitigation Steering Committee identified municipal
enrollment in the Pennsylvania Firewise Communities Program as a Preventive Measure
Hazard Mitigation Measure for the County.
PM-10: Implement a wildfire-prevention public education program consisting
of the development and distribution of an informative brochure
and training for local officials on Pennsylvania’s Firewise Communities
Program.
PM-11: Enroll in the Pennsylvania Firewise Communities Program.
5.1.1.9 Additional, Updated, and Obsolete Mitigation Measures
For the update process, the Mitigation Steering Committee reviewed the original mitigation
measures and determined those which may need to be modified, those which are now
obsolete, and those which need to be added. PM-5 has now become obsolete. Pennsylvania
Department of Labor and Industry adopted the Uniform Construction Code and required that all
municipalities implement the provisions of it in 2004. By doing so, each municipality has now
completed the original PM-5 measure. PM-12 has been added as a modification of the original
PM-6. It reads as follows:
PM-12: Revise or re-adopt a municipal floodplain management ordinance
that is consistent with revised FEMA floodplain mapping to ensure
municipal compliance with NFIP and PA Act 166 floodplain development
regulations, as appropriate.
The modification is necessary due to the fact that FEMA is scheduled to release new
floodplain mapping for Dauphin County in the near future. The new floodplain mapping may
provide additional areas within the municipality which are mapped in detail or may change the
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lines of floodplain area. These changes could result in municipalities having to alter or re-adopt
a floodplain management ordinance in order to maintain compliance with NFIP and PA Act 166.
5.1.2 Emergency Services
Emergency services measures protect people during and immediately following a natural
hazard event. Counties and municipalities typically develop an Emergency Operations Plan
(EOP) to formally document their emergency preparedness and response planning. The local
EOP identifies standard operating procedures for various emergency management personnel
and establishes the location and operating conditions of the emergency operations center
(EOC). As such, adopting and implementing the EOP is a critical first step in providing local
emergency services measures in response to a natural hazard event.
Emergency services measures can be implemented at the local, county, state, and/or
federal level, depending on the severity of the hazard event, and typically include the following:
hazard warning;
hazard response;
critical facilities protection;
health and safety maintenance; and
post-disaster recovery and mitigation.
Implementation of these emergency services measures will work towards the fulfillment of the
following project-planning goals as identified by the Mitigation Steering Committee.
Provide residents with adequate warning of potential floods and other meteorological
events.
Ensure that emergency response services and critical facilities functions
are not interrupted by natural hazards.
Provide safe and efficient evacuation routes during floods and other natural
hazards.
Provide adequate shelters during hazard events.
Ensure that local officials are well trained regarding natural hazards and
appropriate prevention and mitigation activities.
Provide adequate communication systems for emergency management
agencies and emergency response units.
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Reduce impacts from severe storms and/or improve response procedures.
5.1.2.1 Hazard Warning
The first step in dealing with a natural hazard is to know that one is coming. Early
warning of a pending hazard enables residents and business owners to secure their property, to
the greatest extent possible, and move to safety before putting themselves at risk. This consists
of a dual process that incorporates both forecasting and warning procedures. In regard to
flooding, forecasting and warning services are provided for Dauphin County by the NWS Mid-
Atlantic River Forecast Center in State College, Pennsylvania via the Susquehanna River Basin
Flood Forecast and Warning System. The Susquehanna River Basin Flood Forecast and
Warning System uses a network of gauges that measure streamflow and rainfall to provide data
for forecasting river levels and issuing accurate early warnings. Flood forecasts useful to
Dauphin County are issued for the USGS stream gauges on the Susquehanna River at Harrisburg
and Swatara Creek near Hershey and Middletown.
Hazard warning programs generally have two levels of notification:
hazard watch – conditions are right for a suspected hazard, and
hazard warning – a specific hazard has started or is expected to occur.
Under certain conditions, the NWS may issue a “flash flood watch.” This means the amount of
rain expected may cause rapid increases in local stream flows and/or localized ponding.
However, these events are so localized and so rapid that a “flash flood warning” is seldom
issued. Warnings from the NWS are relayed to municipalities by County Emergency Management
Agencies (EMA), who monitor weather radio and broadcast networks. County EMAs are
alerted by PEMA.
After the Flood Forecast and Warning System alerts the local emergency management
coordinator that a flood is coming, the next step is to notify the other local emergency management
personnel and the public that a flood is imminent. The earlier and more accurate the
warning, the greater the number of people who can implement protection measures. A flood or
other natural hazard warning may be disseminated in a variety of ways, including the following:
sirens;
NOAA Weather Radio;
commercial or public radio stations;
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commercial or public television stations;
cable TV emergency news inserts on community bulletin boards;
mobile public address systems;
telephone trees;
Internet weather related sites;
municipal/county/state Internet sites; and
door-to-door contact.
Multiple or redundant systems are most effective: if people do not hear one warning, they may
still get the message from another part of the system.
Given the potentially life-saving importance of hazard warning programs, the Mitigation
Steering Committee identified the following Emergency Services (ES) Hazard Mitigation
Measures to be implemented within the County.
ES-1:
ES-2:
ES-3:
ES-4:
ES-5:
ES-6:
ES-7:
Establish a partnering relationship with the NWS Mid-Atlantic River
Forecast Center to enhance the existing Susquehanna River Basin
Flood Forecast and Warning System via the Advanced Hydrologic
Prediction Services Program.
Coordinate with the USGS, local watershed organizations, and/or
the DCCD to increase the number of USGS and Integrated Flood
Observing and Warning System (IFLOWS) rain and stream gauges
in the County as a potential enhancement to the existing Susquehanna
River Basin Flood Forecast and Warning System.
Increase the number of NOAA Weather Alert radios in public places
across the County (i.e., municipal buildings, public libraries, police
stations, fire stations, etc.) above and beyond that which was
provided/required for the County’s participation in the NWS’s
Storm Ready Program.
Consider expanding the City of Harrisburg’s automated emergency
alert community calling system to the County-level.
Provide alphanumeric pagers to local emergency management coordinators
as a means of improving the County’s warning dissemination
program.
Conduct routine inspections, regular maintenance, and annual
tests on all emergency communications equipment, public address
systems, and hazard alert sirens to ensure unhindered operation
during an emergency event.
Ensure that a planned, coordinated, and effective public warning
dissemination program exists at the local level.
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5.1.2.2 Hazard Response
After a potential hazard is recognized, the first priority is to alert others through the local
warning dissemination program. The second priority is to respond with actions that can prevent
or reduce damage and injuries. These actions are typically defined as standard operating
procedures in an EOP. An updated EOP ensures that all bases are covered and that the
response activities are coordinated and appropriate for the expected hazard. Drills and practice
exercises should be conducted on a routine basis to ensure that all emergency management
personnel understand their assigned duties and are capable of accomplishing them. The result
is a coordinated and appropriate response that demonstrates maximum efficiency in the use of
available and otherwise limited resources.
DEMA worked with the municipalities to develop a County-level EOP that has been
adopted and implemented at the local level by many of the municipalities. These municipalities
are identified on the Capability Matrix located in Chapter 4 of this plan update. Under this
initiative, the municipalities abandoned their existing EOP and responded with actions that are
consistent with the County-level plan. These response actions will be documented in a series of
emergency response checklists that are to be provided by the County. DEMA will assume
responsibility for updating the plan on an annual basis. While municipal participation is optional,
the County is strongly encouraging every municipality to consider the program.
Given the potentially life-saving importance of hazard response activities, the Mitigation
Steering Committee identified the following Emergency Services Hazard Mitigation Measures to
be implemented within the County.
ES-8:
ES-9:
Adopt via resolution, and respond to hazards with actions that are
consistent with, the County-level EOP.
Conduct hazard response practice drills and emergency management
training exercises on an annual basis.
5.1.2.3 Critical Facilities Protection
Protecting critical facilities during a hazard event is a vital part of any emergency services
effort. If a critical facility is threatened and/or damaged during a hazard event, workers
and resources may be drawn away from protecting and assisting other hazard-prone areas of
the community. However, if the vulnerable critical facility was adequately prepared, it would be
better able to support (or at least not detract from) the community’s hazard response efforts. As
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such, the Mitigation Steering Committee used the Critical Facilities Inventory and regional
hazard event profile mapping included in the appendices and GIS data analysis to identify
vulnerable critical facilities throughout the County. As reported in Table 2-6, there are 5 critical
facilities susceptible to dam failure, 5 critical facilities susceptible to flooding, 27 critical facilities
susceptible to land subsidence, and 15 critical facilities susceptible to wildfire. From a hazard
mitigation perspective, those critical facilities susceptible to dam failure, land subsidence, and
wildfire would be protected through implementation of PM-8, SP-9/10, and PP-6, respectively.
Therefore, the Mitigation Steering Committee did not make any additional recommendations for
protecting these critical facilities.
Of the five critical facilities susceptible to flooding, three are located in the City of Harrisburg
and include the Yeshiva Academy on Front Street, Downey Elementary School on Cameron
Street, and the Harrisburg Area Community College off Industrial Road; one is located in
Swatara Township and includes the Circle School along Spring Creek; and one is located in
Williams Township and includes its wastewater treatment plant along Wiconisco Creek. At the
time of the original plan, there was an additional facility located in the City of Harrisburg, Riverside
Elementary School. However, this facility has since closed. From a hazard mitigation
perspective, the Mitigation Steering Committee recognized that none of these critical facilities is
vital to the emergency response effort but do warrant an additional measure of protection. As
such, the Mitigation Steering Committee identified the following Emergency Services Hazard
Mitigation Measure to be implemented within the County.
ES-10: Encourage the owners/operators of Yeshiva Academy, Riverside
Elementary School, Downey Elementary School, Harrisburg Area
Community College, Circle School, and the Williams Township
wastewater treatment plant to develop and implement an emergency
response plan to mitigate potential flooding impacts.
5.1.2.4 Health and Safety Maintenance
Preventing and/or minimizing potential threats to public health and safety during and
immediately following a natural hazard event are critical. After a disaster, many people are
more interested in returning to and repairing their damaged properties than in taking personal
health and safety precautions. Many flood-related drowning victims put themselves in a dangerous
situation by ignoring travel warnings and driving through a flooded area, not realizing
that the bridge has washed out. Cars can float in less than two feet of moving water and can be
easily swept downstream into deeper waters. As such, drowning in vehicles is the number one
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cause of flood-related deaths. Interestingly, the second most frequent cause of flood-related
deaths is through electrocution by way of floodwaters carrying a live electrical current.
Also of concern is what can be carried by floodwaters from upstream areas. Floodwaters
pick up and carry whatever was on the ground upstream. This can include trash, oil,
pesticides, and industrial chemicals. During significant flooding events, wastewater treatment
plants can be inundated and sewer lines can back up. This can result in untreated sewage
mixing with floodwaters, further increasing the public health risk.
Given the potentially life-saving importance of health and safety maintenance activities,
the Mitigation Steering Committee identified the following Emergency Services Hazard Mitigation
Measures to be implemented within the County.
ES-11: Implement the recommendations of the Harrisburg Authority’s ongoing
combined sewer overflow impact study
ES-12: Develop and distribute a public informational pamphlet related to
the potential health and safety implications of various natural hazard
events.
ES-13: Conduct rigorous sampling and analysis of public and private
drinking water supply sources immediately after an inundating
flood event and issue boil water advisories as needed.
5.1.2.5 Post-Disaster Recovery and Mitigation:
After a natural disaster occurs, local governments should engage in activities that will
better prepare people and property for the next disaster. These activities are implemented
during the post-disaster recovery period to prevent people from immediately going “back to
normal” (i.e., the way they were before the disaster) in their potentially hazard-prone location
and condition. These post-disaster activities typically include such things as requiring permits,
conducting inspections, and enforcing the NFIP substantial improvement/substantial damage
regulations. Unfortunately, these activities can be very difficult on a post-disaster basis, especially
for smaller and/or understaffed municipalities. However, if these activities are not carried
out properly, not only does the municipality miss an opportunity to redevelop or clear out its
known hazard areas, but it may also be violating its obligations under the NFIP. As such, the
Mitigation Steering Committee identified the following Emergency Services Hazard Mitigation
Measures to be implemented within the County.
ES-14: Develop a technical proficiency at the municipal level for conducting
post-disaster damage assessments and regulating reconstruc-
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tion activities to ensure compliance with NFIP substantial damage/
substantial improvement requirements.
ES-15: Develop a technical proficiency at the municipal level for assisting
local residents and business owners in applying for hazard mitigation
and assistance funds and identifying cost beneficial hazard
mitigation measures to be incorporated into reconstruction activities.
5.1.2.6 Additional, Updated, and Obsolete Mitigation Measures
For the update process, the Mitigation Steering Committee reviewed the original mitigation
measures and determined those which may need to be modified, those which are now
obsolete, and those which need to be added. ES-3 has become obsolete because it has been
completed. However, the County is considering supplying personal care homes (and possibly
other facilities within the County) with NOAA radios. A new ES-16 has been created to accommodate
this and reads as follows:
ES-16: Increase the number of NOAA Weather Alert radios in public places
across the County which currently do not have them (such as
personal care homes) above and beyond what is required of the
County by the NWS’s Storm Ready Program.
ES-4 has been initiated through the purchase of the Reverse 911 System; however, the
system has not yet been installed within the County. A new ES-17 has been created to address
this and reads as follows:
ES-17: Make the Reverse 911 automated emergency alert system fully operational
within the County.
ES-5 has become obsolete because it has been completed. ES-10 has also become
obsolete because Riverside Elementary School has closed and HACC has created an emergency
response plan. ES-10 has been replaced with ES-18.
ES-18: Encourage the owners/operators of Yeshiva Academy, Downey Elementary
School, Circle School, and the Williams Township
Wastewater Treatment Plant to develop and implement an emergency
response plan to mitigate potential flooding impacts.
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ES-12, ES-14, and ES-15 have been completed; however, they are not going to become
obsolete because continuation of these measures is being encouraged.
During Steering Committee meetings, the following measures were identified as being
necessary to add to the plan. Dauphin County EMA also met to identify any measures which it
felt the plan did not currently include, but should. These additional measures are as follows:
ES-19: Solicit funds in order to continue the operation of river gauges.
ES-20: Encourage citizens, schools, nursing homes, hospitals, etc., to
sign up for AlertPA notifications.
ES-21: Develop flood forecasting maps for the Harrisburg area.
ES-22: Develop and/or obtain a program for the collection and identification
of Special Needs populations for means of notification during
an emergency, also so that proper transportation is provided to
these populations in the event of an evacuation.
ES-23: Develop or obtain software programs to aid in resource management
and EOC management as well as communications to the regional
and state task forces.
ES-24: Establish an alternate EOC location in the event the primary EOC
must be evacuated. The facility should be selected to support the
EOC as well as all of the County Special Teams. This facility
should also be located outside of the TMI EPZ and 100-year floodplain
areas.
ES-25: Encourage the Dauphin County EOC and municipal EOC’s (including
those outside the TMI EPZ) to participate in more exercises and
evacuation drills to practice and gain efficiency in emergency plan
preparedness.
5.1.3 Property Protection
Property protection measures are used to minimize an existing structure’s vulnerability to
a known hazard, rather than trying to modify or control the hazard itself. Property protection
measures involve improvements to privately owned property and must therefore be coordinated
(and potentially even cost-shared) with the respective property owners. Many of these
measures do not affect the appearance or use of the structure, which make them particularly
appropriate for historical sites or landmarks. Implementation of a property protection measure
typically requires acquisition of a local building permit and associated coordination with the local
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uilding, zoning, planning, and/or code enforcement office. As such, property protection
measures include the following:
relocation/acquisition;
elevation;
floodproofing;
insurance;
brush/shrub removal; and
emergency response planning.
Implementation of property protection measures of this nature will work towards the fulfillment of
the following project-planning goals as identified by the Mitigation Steering Committee.
Ensure that property owners and potential property owners are aware of
the availability and benefits of obtaining federal flood insurance.
Improve the participation rate in federal flood insurance through education.
Minimize future damage due to flooding of the Susquehanna River and its
tributaries.
Reduce impacts related to flash flooding and stormwater problems.
Ensure that high-risk, pre-FIRM residential structures do not get repeatedly
flooded by using retrofitting techniques to reduce the flood risk to the
properties.
Reduce the impact of flooding on commercial structures through retrofitting
techniques.
Investigate retrofitting alternatives to reduce impacts from other natural
hazards.
Reduce threats related to wildfires.
As previously mentioned, 13 representative floodplain structures were identified from
throughout the County (see Section 2.4.3) and analyzed to determine approximate loss estimates
for the 100-year flood event. These 100-year flood loss estimates, along with additional
structure specific information collected in the field, were input into FEMA’s Benefit-Cost Analysis
(BCA) Limited Data Module to determine the cost effectiveness of implementing various property
protection measures for these 13 representative floodplain structures. In FEMA terms, cost
effectiveness is measured by means of a benefit-cost ratio; which is a ratio of project benefits to
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project costs. If the project benefits exceed the project costs, the benefit-cost ratio is greater
than 1.0 and the project is considered to be cost-effective; if the project benefits do not exceed
the project costs, the benefit-cost ratio is less than 1.0 and the project is not considered to be
cost-effective.
While project costs are relatively simple to estimate, determining project benefits can be
much more difficult. This is because project benefits measure the damages avoided as a result
of a property protection project from flood events of varying frequency and intensity that can
occur over the life of the project. For this reason, FEMA developed the BCA Modules to aid
users in estimating project benefits and computing benefit-cost ratios.
The benefit-cost analyses conducted for these 13 representative floodplain structures
considered the following alternative property protection measures.
Relocation/Acquisition – Moving/taking the existing structure outside of
the floodplain.
Elevation – Raising the existing structure on a foundation constructed
above the flood elevation.
Dry Floodproofing – Making the structure watertight by strengthening
the structural elements and using sealants and shields to resist low-level
flood events.
Wet Floodproofing – Using flood-resistant materials and protecting utilities
and other equipment to resist flood damage when waters enter the
structure.
However, a detailed review of these mitigation alternatives indicated that dry floodproofing is not
appropriate for any of the 13 representative floodplain structures. Dry floodproofing is typically
not appropriate for structures with basements or flood elevations greater than three feet in
depth. Therefore, the dry floodproofing alternative was eliminated and not considered for
benefit-cost analysis.
A summary of the benefit-cost analysis results for the 13 representative floodplain
structures is shown in Tables 5-1 and 5-2. The complete results (including supporting documentation)
of the benefit-cost analyses are included in the Appendices. These benefit-cost
ratios were used to assist in the identification of an appropriate property protection measure for
each of the 13 representative floodplain structures. Ideally, a benefit-cost ratio should be higher
than 1.0 to be considered reasonably grant-eligible. Lower ratios still provide a relative degree
of project feasibility, but are also indicative of projects that may require private funding or funds
from sources other than FEMA grants. The representative floodplain structures and their
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identified property protection measure were then used to develop a County-specific guide to
identifying and selecting an appropriate property protection measure. This County guide (see
Table 5-3) takes into consideration the type/use of the structure, the foundation of the structure,
and the associated 100-year flood impact to make a general recommendation on the most
appropriate property protection measure for any given structure in the County. As such, this
guide can be used throughout the County to assist in the identification and selection of appropriate
property protection measures. Additional information on property protection measures
and how they apply to the 13 representative floodplain structures is provided below. In accordance
with PEMA directives, Hazard Mitigation Opportunity Forms for the 13 representative
floodplain structures are included in the Appendices.
TABLE 5-1
SUMMARY OF BENEFIT-COST ANALYSIS RESULTS FOR RESIDENTIAL
REPRESENTATIVE STRUCTURES
FLOODPLAIN
REPRESENTATIVE STRUCTURE
BENEFIT-COST RATIO BY FLOOD MITIGATION METHOD
ELEVATION
RELOCATION
WET
FLOODPROOFING
FLOODWALLS
Fishing Creek Valley 1.02 0.95 N/A 0.48
Lawton Branch of Spring Creek 0.33 0.29 0.19 0.40
Susquehanna River - Shipoke Duplex 1.67 1.61 N/A 1.72
Stony Creek - Middle Paxton Township 1.31 1.18 N/A 0.83
Susquehanna River - Middle Paxton 0.29 0.27 0.07 0.21
Swatara Creek - Middletown Borough 0.11 0.14 0.01 0.18
Wiconisco Creek - Millersburg Area 0.39 0.35 0.10 0.20
Swatara Creek - South Hanover Township 1.54 1.26 N/A 1.04
Swatara Creek - Royaltown Borough 0.73 0.67 N/A 0.43
Manada Creek 0.40 0.33 0.25 0.27
N/A – Not Applicable
TABLE 5-2
SUMMARY OF BENEFIT-COST ANALYSIS RESULTS
FOR COMMERCIAL/INDUSTRIAL REPRESENTATIVE STRUCTURES
FLOODPLAIN
REPRESENTATIVE
STRUCTURE
ELEVATION
BENEFIT-COST RATIO BY FLOOD MITIGATION METHOD
DEMOLISH
& REBUILD RELOCATION
WET FLOOD-
ACQUISITION
PROOFING
FLOOD-
WALLS
Susquehanna River - PSAB Building 0.46 N/A N/A 0.30 N/A 2.59
Paxton Creek - Subway Café 1.16 N/A 1.13 N/A N/A N/A
Paxton Creek - Dayton Parts N/A 0.44 N/A 0.68 1.33 N/A
N/A – Not Applicable
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100-Year
Flood
Impact
High
Velocity
and/or
Floodway
0-2’ In
Basement
2’-8’ In
Basement
< 1’ First
Floor
TABLE 5-3
DAUPHIN COUNTY PROPERTY PROTECTION GUIDE
Type of Structure
Residential
1-2 Story Wood Frame 1-2 Story Masonry
With Basement Slab-On-Grade Crawlspace With Basement Slab-On-Grade Crawlspace
Commercial 1 Industrial 1
Relocation/Acquisition 2 Relocation/Acquisition 2 Relocation/Acquisition 2 Relocation/Acquisition 2 Relocation/Acquisition 2 Relocation/Acquisition 2 Relocation/Acquisition 2 Relocation/Acquisition 2
Sump Pump 3 and/or
Wet Floodproofing 4 N/A N/A Sump Pump 3 and/or
4 N/A N/A N/A N/A
Wet Floodproofing
Wet Floodproofing 4 N/A N/A Wet Floodproofing 4 N/A N/A N/A N/A
Wet Floodproofing 4
Wet Floodproofing 4
Or
Dry Floodproofing 3 Or
Wet Floodproofing 4 Dry Floodproofing 3 Wet Floodproofing 4 Dry Floodproofing 3 Dry3 or Wet 4
Elevation 5 Elevation 5 Floodproofing
1’-3’ First
Floor
Elevation 5
Elevation 5
Elevation 5
Elevation 5
Elevation 5
Elevation 5
3’-8’ First
Or
Or
Or
Or
Or
Or
Floor
Relocation/Acquisition 6 Relocation/Acquisition 6 Relocation/Acquisition 6 Relocation/Acquisition 6 Relocation/Acquisition 6 Relocation/Acquisition 6
Elevation 7
Elevation 7
Elevation 7
Elevation 7
Elevation 7
Elevation 7
>8’
Or
Or
Or
Or
Or
Or
Relocation/Acquisition 6 Relocation/Acquisition 6 Relocation/Acquisition 6 Relocation/Acquisition 6 Relocation/Acquisition 6
Notes: These recommendations are for planning purposes only. Professional expertise should be sought before taking any flood mitigation action.
Some projects may not meet FEMA cost benefit requirements, thereby requiring property owner or other funding sources.
Elevation 5 Dry Floodproofing 3 Elevation 5 Elevation 5 Dry Floodproofing 3 Elevation 5 Dry Floodproofing 3 Dry3 or Wet 4
Elevation 5 or
Relocation/Acquisition 6
Floodproofing
Wet Floodproofing 4 or
Relocation/Acquisition 6
Relocation/Acquisition 6 Relocation/Acquisition 6 Relocation/Acquisition 6
1
2
3
4
5
6
7
Assuming slab-on-grade foundation.
Floodway location/vulnerability to high velocity flows warrant relocation and/or acquisition.
See dry floodproofing text later in this chapter.
See wet floodproofing text later in this chapter.
See elevation text later in this chapter.
See relocation/acquisition text later in this chapter.
Only appropriate for seasonal structures.

5.1.3.1 Relocation/Acquisition
Moving a building to higher ground (i.e., relocation) and/or purchasing and demolishing a
flood-prone building (i.e., acquisition) are the surest ways to minimize potential flooding impacts.
Municipalities with areas subject to ice jams, flash flooding, high velocity flows, deep water, or
where the only safe approach is to remove the building, should consider relocation and/or
acquisition. Removing buildings from the floodplain is not only the most effective flood protection
measure available, it is also a way to convert a problem area into a community asset and
obtain environmental benefits.
Relocation is preferred for large lots that include buildable area outside the floodplain or
where the owner already has a new flood-free lot available. Relocation can be expensive,
however. While almost any building can be moved, the cost goes up for heavier structures,
such as those with exterior brick and stone walls, and for large or irregularly shaped buildings.
As shown in Table 5-4, the cost of moving a 1,000-square-foot building can range from $29 to
$65 per square foot, depending on the construction type (e.g., frame or masonry) and the type
of existing foundation (e.g., basement, crawlspace, or slab-on-grade). There are also a number
of factors that affect the feasibility of relocation such as road width and grade, density of overhead
utilities, and other related factors.
TABLE 5-4
RELOCATION COST GUIDE
CONSTRUCTION TYPE EXISTING FOUNDATION RELOCATION COST a
Frame b
Masonry
Basement
Crawlspace
Slab-on-Grade
Basement
Crawlspace
Slab-on-Grade
Source: FEMA 259 2 nd Edition/June 2001 (adjusted to 2003 values)
a
per square foot of building footprint
b
for frame building with masonry veneer, add 10 percent
$34
$29
$54
$52
$34
$65
It should be noted that the costs shown in Table 5-4 do not represent the entire cost of a
relocation project. Additional costs may be necessary for acquiring a new lot on which to place
the relocated building and for restoring the old site. Also, relocation costs do not increase
proportionally with the size of a building. The cost per square foot for relocating a building
larger than 1,000 square feet may be less, but some larger buildings may have to be cut and the
parts moved separately.
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Like relocation, acquisition of buildings in a flood-prone area ensures that they will no
longer be subject to damage. The major difference is that acquisition is undertaken by a
government agency; so the cost is not borne by the property owner, and the land is converted to
a public use, such as a park. Acquisition, followed by demolition, is most appropriate for buildings
that are difficult to move, such as larger, slab-on-grade foundation or masonry structures,
and dilapidated structures that are not worth protecting. An acquisition budget should be based
on the median price of similar properties in the community plus $10,000 to $20,000 for appraisals,
abstracts, title opinions, relocation benefits, and demolition. Costs may be lower after a
flood. For example, the municipality may have to pay only the difference between the full price
of a property and the amount of the flood insurance claim received by the owner. Municipalities
should be cautious, however, to avoid creating a “checkerboard” acquisition pattern in which
non-adjacent properties are acquired. This can occur when some owners, especially those who
have and prefer a waterfront location, prove reluctant to leave. Creating such an acquisition
pattern in a community simply adds to the maintenance costs that taxpayers must support.
Occasionally, acquisition and relocation projects are undertaken jointly. The purchasing
agency typically sells the building for salvage. Sometimes, the original owner of the acquired
building can make arrangements to buy it back at the salvage value. The advantage of this
approach is that a new owner relocates the building rather than demolishes it. This way, the
owner gets to keep the building and may have enough money from the sale to pay for a new lot
and moving expenses.
Within Dauphin County, the representative floodplain structure along Stony Creek in
Middle Paxton Township (see Appendix F) serves as an excellent sample structure for potential
relocation/acquisition. At this location, the representative floodplain structure is located immediately
adjacent to Stony Creek and is dangerously susceptible to high velocity floodway flows. In
addition, the 100-year flood event results in approximately seven feet of water on the first floor
of this structure. Even the 10-year flood event results in approximately three feet of water on
the first floor of this structure. As such, given this structure’s location within the regulatory
floodway and its severe vulnerability to deep high velocity flooding, relocation and/or acquisition
appear to be the most appropriate and effective flood hazard mitigation options. Based on a
number of similar occurrences throughout the County, the Mitigation Steering Committee
identified the following Property Protection (PP) Hazard Mitigation Measure for potential implementation.
PP-1:
Relocate and/or acquire known flood-prone structures in accordance
with the general guidelines of Table 5-3.
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5.1.3.2 Elevation
Raising a building above the flood level (i.e., elevation) is the best on-site property
protection method (see Figures 5-1 through 5-4). Water flows under or around the building,
causing little or no damage to the structure or its contents. Buildings can be elevated on an
open foundation (i.e., posts, piles or columns), continuous foundation walls, or compacted
earthen fill. While elevating on compacted fill is sometimes the most desirable elevation solution,
it is a complicated alternative. The building has to be temporarily moved so that the fill can
be placed and properly compacted. As such, elevating on fill may prove to be more costly than
elevating on an open foundation or continuous foundation walls. In addition, it must be remembered
that the streets, utilities, and other infrastructure that serve an elevated building will still
be vulnerable to damage during a flood. Therefore, the elevated building may be isolated and
without utilities during a flood. There will also be a risk to the occupants who may try to enter or
leave the building during a flood.
Elevating a building will also change its appearance. If the required amount of elevation
is low, the result is similar to putting a building on a two- or three-foot crawlspace. If the building
is raised two feet, the front door would be three steps higher than before. If the building is
raised eight or more feet, the lower area can be wet floodproofed (see next section) and used
for parking and/or storage of items that will not be damaged by floodwaters.
Elevating a building above the flood level is cheaper than relocating it and can be less
disruptive to a neighborhood. In addition, elevation has proven to be an acceptable means of
complying with NFIP regulations that require substantially damaged (and new) buildings to be
elevated above the 100-year flood elevation when repaired (or constructed) in a floodplain.
Table 5-5 shows the costs of elevating various types of buildings a total of two feet on either an
open foundation or continuous foundation walls. As shown in Table 5-5, the cost can range
from $27 to $75 per square foot, depending on the construction type (e.g., frame or masonry)
and the type of existing foundation (e.g., basement, crawlspace, or slab-on-grade). The costs
for extending utility lines and adding or extending staircases are included. The costs for elevating
buildings with slab-on-grade foundations are based on the assumption that the building is
raised with the existing slab attached. To estimate the cost of elevating more than two feet, add
$0.80 per square foot of building footprint for each additional foot of elevation up to eight feet.
For elevations greater than eight feet, add $1.05 per square foot for each additional foot of
elevation.
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FIGURE 5-1
STEEL I-BEAMS AND JACKS ARE INSTALLED
IN PREPARATION FOR LIFTING THE HOUSE
FIGURE 5-2
THE HOUSE, SUPPORTED ON THE I-BEAMS, IS RAISED ON THE JACKS
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FIGURE 5-3
NEW MASONRY PIERS ARE CONSTRUCTED TO SUPPORT THE HOUSE,
AND THE BASEMENT IS FILLED WITH DIRT
FIGURE 5-4
WHEN THE HOUSE HAS BEEN RAISED TO THE DESIRED HEIGHT,
THE NEW MASONRY PIERS ARE COMPLETED
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TABLE 5-5
ELEVATION COST GUIDE
CONSTRUCTION TYPE EXISTING FOUNDATION ELEVATION COST a
Frame b
Masonry
Basement or Crawlspace
Slab-on-Grade
Basement or Crawlspace
Slab-on-Grade
$27
$75 c
$55
$75 c
Source: FEMA 259 2 nd Edition/June 2001 increased to 2003 values and by 50% based on engineering judgment
a
per square foot of building footprint
b
for frame building with masonry veneer, add 10 percent
c
price shown for raising the building with the slab attached
Within Dauphin County, the representative floodplain structure along Fishing Creek in
Middle Paxton Township (see Appendix F) serves as an ideal sample structure for potential
elevation. This representative floodplain structure is a typical two-story residence of wood
frame construction with a basement foundation. The structure is located within the 100-year
floodplain of Fishing Creek, but not within the regulatory floodway. The 100-year flood event
results in full basement flooding and approximately four feet of water on the first floor of this
structure. Even the 10-year flood event results in full basement flooding, but little to no first floor
flooding. Given this structure’s location outside the regulatory floodway or other high velocityflooding
situation, its wood frame construction and basement foundation (less expensive to
elevate than masonry and slab-on-grade structures), and its vulnerability to significant first floor
flooding during a 100-year event, elevation appears to be the most appropriate flood hazard
mitigation option. Based on a number of similar occurrences throughout the County, the Mitigation
Steering Committee identified the following Property Protection Hazard Mitigation Measure
for potential implementation.
PP-2:
Elevate known flood-prone structures in accordance with the general
guidelines of Table 5-3.
5.1.3.3 Floodproofing
In areas of relatively low flood threat (e.g., where flooding is infrequent or characterized
by low velocity flows or shallow depths), dry floodproofing, and wet floodproofing can be efficient
approaches to minimizing potential damages. These approaches can also be less disruptive to
a neighborhood than relocation, acquisition, and elevation. However, it must be remembered
that the streets, utilities, and other infrastructure that serve a floodproofed building will still be
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vulnerable to damage during a flood. Therefore, the floodproofed building may be isolated and
without utilities during a flood. There will also be a risk to the occupants who may try to enter or
leave the building during a flood. A brief description of these two floodproofing approaches is
provided below.
5.1.3.3.1 Dry Floodproofing
Dry floodproofing involves sealing a building against floodwaters. All areas below the
flood protection level are made watertight and impermeable to flood waters (see Figure 5-5).
FIGURE 5-5
A TYPICAL DRY FLOODPROOFED HOUSE
Examples of dry floodproofing modifications include the following:
installing watertight shields over doors and windows;
reinforcing walls to withstand floodwater pressures and impact forces
generated by floating debris;
using membranes and other sealants to reduce seepage of floodwater
through walls and wall penetrations;
installing drainage collection systems and sump pumps to control interior
water levels, collect seepage, and reduce hydrostatic water pressures on
the floor slab and walls;
installing backflow valves to prevent the entrance of floodwater or sewage
flows through utilities; and
anchoring the building to resist flotation, collapse, and lateral movement.
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Dry floodproofing is only recommended in areas where floodwaters are less than three feet (two
feet plus one foot of freeboard) in depth and relatively slow-moving. It may also be appropriate
for buildings that are too expensive to elevate (e.g., slab-on-grade buildings). The flood protection
level for dry floodproofing should be no more than three feet above the top of the foundation
because building walls and floors cannot typically withstand the pressure of deeper water. As
such, dry floodproofing should not be used in areas where floodwaters are expected to remain
high for long periods. In addition, dry floodproofing is not appropriate for any structure that has
a basement. The disadvantages of dry floodproofing include the deterioration of waterproofing
compounds over time and the dependence on human action for the installation of closures on
windows and doorways. Each of these disadvantages may lead to failure of the dry floodproofing.
Table 5-6 provides cost information for some typical dry floodproofing activities.
TABLE 5-6
DRY FLOODPROOFING COST GUIDE
TYPE COST UNIT
Sprayed-on Cement (above grade) $3.50 Square foot
Waterproof Membrane (above grade) $1.17 Square foot
Asphalt (two coats below grade) $1.17 Square foot
Perimeter Drainage $33 Linear foot
Plumbing Check Valve $660 Lump sum
Sump Pump (with backup battery) $1,060 Lump sum
Metal Flood Shield $77 Square foot
Wood Flood Shield $24 Square foot
Source: FEMA 259 2 nd Edition/June 2001 (adjusted to 2003 values)
Dry floodproofing of new and existing nonresidential buildings in the 100-year floodplain
is permitted under the NFIP. Dry floodproofing of existing residential buildings in the 100-year
floodplain is also permitted as long as the building is not substantially damaged or being substantially
improved (exceeding 50% of the structure’s market value). Owners of buildings
located outside the 100-year floodplain can always use dry floodproofing techniques. The
design and planning considerations that must be taken into account include the following.
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Warning Time – Sufficient lead time is necessary before a flood to evacuate
a flood-prone building and implement dry floodproofing measures that
require human intervention (e.g., installing a flood shield).
Safety and Access – There must remain a safe escape route for all persons
responsible for implementing dry floodproofing techniques that require
human intervention. Roads to be used as evacuation routes must
remain passable as floodwaters rise.
Flood Velocity – Where flood velocities exceed five feet per second, hydrodynamic
forces are too great to implement floodproofing techniques.
Flood Depth – Generally, the cost of dry floodproofing is too high in areas
where flood depths are greater than three feet. As flood depths exceed
three feet, hydrostatic flood forces mandate a more expensive solution.
Flood Frequency – Dry floodproofing is generally not appropriate for
buildings that flood frequently. The cost of the wear and tear on the building
combined with the frequent business interruption warrants a different
approach such as relocation.
Duration – Dry floodproofing should not be used in areas where floodwaters
are expected to remain for over four to eight hours. Hydrostatic
pressures will eventually overcome components of the floodproofing system,
allowing water to enter the structure. It is very expensive to successfully
floodproof a structure, especially a historic structure, which will
be exposed to floodwaters for more than four to eight hours.
Within Dauphin County, none of the representative floodplain structures were identified
as an ideal sample for implementing dry floodproofing measures due to their basement foundations
and/or significant flood depths. In certain instances, however, dry floodproofing is an
appropriate flood hazard mitigation option for a number of the County’s flood-prone buildings.
As such, the Mitigation Steering Committee identified the following Property Protection Hazard
Mitigation Measure for potential implementation.
PP-3:
Dry floodproof known flood-prone structures in accordance with
the general guidelines of Table 5-3.
5.1.3.3.2 Wet Floodproofing
Wet floodproofing, unlike dry floodproofing, allows floodwater to enter a structure in
order to counterbalance the hydrostatic pressure on the walls, surfaces, and supports of the
structure. This technique is often used when other techniques are not technically feasible or too
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costly for the level of flood impact. Wet floodproofing is appropriate for structures with uninhabited
areas below the flood elevation, such as unfinished basements, garages, and crawlspaces
(see Figure 5-6). However, because wet floodproofing allows floodwater to enter a structure,
modifications must be made to minimize damage to the portion of the structure below the flood
elevation and its contents. Typically, the structure is designed so that walls and floors below the
flood elevation are resistant to damage from floodwaters, and utilities and other valuable equipment
are located above the flood elevation.
FIGURE 5-6
A TYPICAL WET FLOODPROOFED HOUSE
It is important to note that, although wet floodproofing can be an effective and economical
means of reducing flood damage, it does not satisfy NFIP regulatory requirements for
substantially damaged and substantially improved structures in the 100-year floodplain. Communities
that want to wet floodproof such structures may do so only through the issuance of a
variance from the NFIP requirements. The NFIP allows variances for wet floodproofing for the
following categories of structures.
Historic Buildings – repair and rehabilitation of historic structures is contingent
on a determination by the community that the proposed work will
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not preclude the structure’s continued designation as a historic structure
and that the variance is the minimum effort necessary to preserve the historic
character and design.
Accessory Structures – usually limited to buildings used for parking or limited
storage.
Structures Functionally Dependent on Close Proximity to Water – these
structures include certain types of docking, port facilities, etc.
Certain Agricultural Structures – the NFIP recognizes that wet floodproofing
may be appropriate for certain types of agricultural structures located
in wide, expansive floodplains.
When wet floodproofing is used, the occupants of the wet floodproofed structure will
need adequate warning of an impending flood so that they will have time to leave safely. If the
wet floodproofing design requires human intervention (e.g., moving vulnerable materials to a
location above the flood level), there must remain a safe escape route for all people responsible
for human intervention activities. Roads to be used as evacuation routes must remain passable
as floodwaters rise.
All structural and non-structural components in the wet floodproofed area of a structure
must be constructed of materials that are durable, resistant to flood forces, and resistant to
deterioration caused by repeated exposure to floodwaters (e.g., masonry and concrete). Wall
elements, insulation, and flooring should all be constructed of materials that will not be damaged
by water or retain water once floodwaters have receded. For example, when water enters a
building and inundates a standard cavity wall system, the cavity wall will retain water, silt, and
other flood contaminants, which can result in structural damage and economic losses. In
addition, the structural foundation must be designed and constructed to withstand frequent
inundation without failure. It is very important that the structure is properly anchored to the
foundation to prevent uplift and separation. Electrical and mechanical systems installed within
the wet floodproofed area should be located above the expected flood level (see Figure 5-6).
For example, in a basement storage area or garage that may be flooded with two feet of water
(above the floor) during a flood, locating outlets, heaters, and other utility elements three feet or
more above the floor can help to prevent damage to electrical and mechanical systems. Such
relocations should be coordinated with the respective utility provider. Table 5-7 provides cost
information for wet floodproofing to various heights.
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TABLE 5-7
WET FLOODPROOFING COST GUIDE
CONSTRUCTION
TYPE
Wood Frame or
Masonry
HEIGHT OF WET
FLOODPROOFING
Two Feet
Four Feet
EXISTING
FOUNDATION
COST
Basement $2.70
Crawlspace $2.10
Basement $5.55
Crawlspace $5.18
Eight Feet Basement $15.90
Crawlspace
N/A
UNIT
Square foot
Square foot
Square foot
Source: FEMA 259 2 nd Edition/June 2001 adjusted to 2003 values and increased 50% to account for finished
basement and protection of utilities
Within Dauphin County, the representative floodplain structure along Manada Creek in
East Hanover Township (see Appendix F) serves as an ideal sample structure for potential
implementation of wet floodproofing measures. This representative floodplain structure is a
one-story residence of wood frame construction with a basement foundation. The structure is
located within the 100-year floodplain of Manada Creek, but not within the regulatory floodway.
The 100-year flood event results in full basement flooding and approximately one foot of water
on the first floor of this structure. The 10-year flood event results in only basement flooding.
Even the 50-year flood event results in only basement flooding, with little to no first floor flooding
for this structure. Given this structure’s location outside the regulatory floodway or other high
velocity flooding situation and its minimal vulnerability to first floor flooding, wet floodproofing of
the basement area appears to be the most appropriate flood hazard mitigation option. Based
on a number of similar occurrences throughout the County, the Mitigation Steering Committee
identified the following Property Protection Hazard Mitigation Measure for potential implementation.
PP-4:
Wet floodproof known flood-prone structures in accordance with
the general guidelines of Table 5-3.
5.1.3.4 Insurance
Insurance has the advantage that, as long as the policy is in force, the property is
covered and no human intervention is needed for the measure to work. Although most home-
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owners’ insurance policies do not cover a property for flood damage, an owner can insure a
building through the NFIP. A municipality must participate in the NFIP in order to make flood
insurance available to its residents. As evidenced by Table 2-3, only 2 of Dauphin County’s 40
municipalities do not participate in the NFIP. Those municipalities are Berrysburg Borough and
Penbrook Borough, which do not have any known flood hazard areas. As of March 2009, there
were a total of 3,073 flood insurance policies in force in Dauphin County. Table 2-7 indicates
that, as of January 2009, Dauphin County residents have submitted a total of 3,318 flood insurance
claims and have received over $32.6 million in claims payments since joining the flood
insurance program. It is important to note, however, that not every flood-prone building in the
County is covered under a flood insurance policy. Table 2-6 indicates that there are over 5,300
structures in the County that are vulnerable to potential flooding impacts during a 100-year
event. While some of these structures may not warrant insurance coverage (i.e., sheds, pavilions,
garages, and other miscellaneous accessory structures), it is clear that, with only 3,073
policies in force, there are a number of insurable structures in the County that are not covered
under a flood insurance policy. As such, the Mitigation Steering Committee identified the
following Property Protection Hazard Mitigation Measure for implementation within the County.
PP-5:
Encourage uninsured property owners in known flood hazard areas
to purchase flood insurance through the NFIP.
5.1.3.5 Brush/Shrub Removal
Removing excess brush and shrubby plants from the immediate vicinity of buildings in
potential wildfire hazard areas can help prevent the buildings themselves from catching on fire.
Brush and shrubby plants can serve as fuel for wildfires and cause them to spread more quickly.
Having this available fuel in close proximity of buildings only increases the likelihood of those
buildings to catch on fire during a wildfire event. By removing excess brush and shrubby plants
from the immediate vicinity of a building (i.e., 50 to 100 feet), thereby decreasing and/or eliminating
the available fuel load, the likelihood of that building to succumb to fire during a wildfire
event decreases dramatically. Given Dauphin County’s vulnerability to wildfire hazards, and the
large number of residential structures that are located in potential wildfire hazard areas (See
Figure 2-5), the Mitigation Steering Committee identified the following Property Protection
Hazard Mitigation Measure to be implemented within the County.
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PP-6:
Encourage property owners in potential wildfire hazard areas to
remove all excess brush and shrubby plants from the immediate
vicinity (i.e., 50 to 100 feet) of all buildings.
5.1.3.6 Emergency Response Planning
In certain situations, implementation of physical property protection measures (i.e.,
relocation, elevation, or floodproofing) may not be technically or fiscally appropriate. This is
most often the case for larger flood-prone business and industry buildings, where relocation is
undesirable and retrofitting techniques may be too costly or not technically feasible. As such,
alternatives to physical property protection measures must be explored. One alternative to
implementing physical property protection measures is to develop an emergency response plan
specific to the particular business or industry. An emergency response plan is a guidance
document that identifies and describes specific emergency preparation and response procedures
to be implemented on a pre- and post-disaster basis in order to minimize potential flooding
impacts. As such, emergency response planning can serve to minimize potential impacts to
both the structure and its contents/inventory. In this manner, emergency response planning for
a particular business or industry would constitute a property protection measure. FEMA guidance
on developing and implementing a business/industry specific emergency response plan is
included in the appendices. Given the wide-scale applicability and the potential reduction in
flooding impacts, the Mitigation Steering Committee identified the following the Property Protection
Hazard Mitigation Measure to be implemented within the County.
PP-7:
Encourage local business and industry owners in known flood
hazard areas to develop an emergency response plan as a potential
alternative to implementing a physical property protection
measure, where otherwise not technically or fiscally appropriate.
5.1.3.7 Additional, Updated, and Obsolete Mitigation Measures
For the update process, the Mitigation Steering Committee reviewed the original mitigation
measures and determined those which may need to be modified, those which are now
obsolete, and those which need to be added. A new PP-8 has been added as an additional
measure which is an expansion upon PP-5. Due to the new floodplain mapping for Dauphin
County which FEMA will be releasing this year, there may be some properties which were not in
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the floodplain that may now be in the floodplain and are unaware that they are eligible for and
should purchase insurance under NFIP. PP-8 reads as follows:
PP-8
Educate and encourage uninsured property owners to purchase
flood insurance through the NFIP who are identified as being located
within the flood hazard areas on the new FEMA 100-year
floodplain mapping.
5.1.4 Structural Projects
Structural projects are typically constructed to keep floodwaters and other natural
hazards away from select areas. They are usually designed by engineers and managed or
maintained by public works staff. From a flood hazard mitigation standpoint, structural projects
can be used to control flows and water surface elevations for both flood minimization and
recreational purposes. However, due to their limiting costs and potential environmental implications,
structural projects are not normally constructed to protect individual properties, but are
usually large-scale undertakings designed to protect numerous people and properties. As such,
structural hazard mitigation projects typically include the following:
dams/levees/floodwalls;
bridge/culvert modifications;
channel modifications/diversions;
firebreaks;
sinkhole abatement;
landslide abatement; and
emergency water source development.
Implementation of structural projects of this nature will work towards the fulfillment of the following
project-planning goals as identified by the Mitigation Steering Committee.
Ensure that existing drainage systems (pipes, culverts, channels) are adequate
and functioning properly.
Minimize future damage due to flooding of the Susquehanna River and its
tributaries.
Reduce impacts related to flash flooding and stormwater problems
Investigate structural solutions to natural hazards.
Reduce threats related to wildfires.
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Reduce threats related to hurricanes.
Reduce threats related to landslides.
5.1.4.1 Dams/Levees/Floodwalls
Dams, levees and floodwalls are similar in that they control flooding by restricting
floodwaters from reaching/inundating protected areas. Dams, levees and floodwalls are probably
the best-known forms of structural flood control projects that have been implemented in the
United States. In fact, examples of all three of these structural flood control projects have been
constructed and used effectively in the Susquehanna River Basin to minimize flooding impacts.
It is important to note, however, that just like any other engineering feature, if the design capacity
of a dam, levee and/or floodwall is exceeded, its functional utility becomes compromised. As
such, dams, levees and floodwalls can give a false sense of security to the property owners that
they protect.
Map analysis and field reconnaissance conducted by the Mitigation Steering Committee
resulted in the identification of several locations in the County that a dam, levee and/or floodwall
may prove to be a feasible and prudent flood hazard mitigation option. In general, the Mitigation
Steering Committee only considered structural flood control projects in areas where there is a
significant flooding impact to a multitude of structures. Under any other circumstances, construction
of a structural flood control project would not be considered cost-beneficial. Implementation
of any of these structural hazard mitigation project recommendations would first need to
be evaluated for its long-term viability and economic feasibility. These potential structural
project (SP) recommendations are listed below.
SP-1:
SP-2:
SP-3:
Investigate the feasibility of constructing a levee/floodwall system
and/or a floodwater storage reservoir along Rattling Creek, Bear
Creek and/or Wiconisco Creek to minimize/eliminate Lykens Borough’s
extensive flood hazard potential.
Investigate the feasibility of increasing the Lawnton Branch of
Spring Creek’s underground flow capacity to minimize/eliminate
the Lawnton area’s flood hazard potential.
Investigate the feasibility of constructing a levee/floodwall system
along Swatara Creek between East Main Street and the Pennsylvania
Turnpike to minimize Middletown Borough’s flood hazard potential.
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SP-4:
Investigate the feasibility of constructing a levee/floodwall system
along the Susquehanna River to minimize Highspire Borough’s
backwater flood hazard potential.
5.1.4.2 Bridge/Culvert Modifications
In the wake of a significant storm event, undersized bridge and culvert crossings of local
streams and watercourses can result in floodwater backing up upstream of the structure causing
significant flooding problems. Therefore, from a flood hazard mitigation standpoint, bridge/
culvert modifications typically involve the replacement, enlargement, and/or removal of existing
roadway and railway bridges and culverts that are known to cause flooding problems. Regulations
set forth in PennDOT Design Manual Part 4, and the PA DEP’s Title 25, Chapter 105 state
that all new bridges and culverts shall be designed and constructed to pass a 25-year frequency
flood flow in rural areas, a 50-year frequency flood flow in suburban areas, and a 100-year
frequency flood flow in urban areas. In addition, the regulations state that the structure must
pass the 100-year frequency flood flow with less than a 1.0-foot increase in the natural unobstructed
100-year water surface elevation, except where the structure would be located in a
regulatory floodway delineated on a FEMA Flood Boundary and Floodway Map, in which case,
no increase in the 100-year water surface elevation will be permitted. While these regulations
now exist for the design and construction of new bridge and culvert projects, many existing
bridges and culverts throughout the County were constructed prior to these regulations being in
place. Additionally, while many of these existing bridges and culverts may have been capable
of passing design flows when they were built, upstream development could result in increased
peak flows to a point that the existing structure is no longer hydraulically adequate. Replacing,
enlarging, or removing these known problematic structures can go a long way in minimizing the
County’s flooding problems.
As previously mentioned, the DCCD is active in the PA DEP’s Act 167 Stormwater
Management Planning Program and has completed stormwater management plans for most of
the County’s watersheds. Part of the Act 167 stormwater management planning process
involves a hydraulic capacity analysis of the subject watershed’s bridge and culvert stream
crossings. The Mitigation Steering Committee used this existing data to identify those bridges
and culverts that are unable to pass the 10-year frequency flood flow. Structures that are not
able to pass the 10-year frequency flood flow were considered to be significant obstructions in
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need of potential modification. As such, the Mitigation Steering Committee identified the following
Structural Project Hazard Mitigation Measure to be implemented within the County.
SP-5:
Coordinate with the local municipality and/or PennDOT on the potential
feasibility of replacing, removing, or enlarging those bridge
and culvert stream crossings that were identified during the Act
167 Stormwater Management Planning process as being unable to
pass the 10-year frequency flood flow.
5.1.4.3 Channel Modifications/Diversions
Channel modifications and diversions involve the physical alteration of a channel to
modify its hydrologic and hydraulic characteristics in order to accomplish a given purpose.
From a flood hazard mitigation standpoint, the typical purpose of a channel modification or
diversion project is to minimize overbank flooding by increasing the capacity of the channel,
regulating flow within the channel, relocating the channel, or diverting flow from the channel.
With today’s modern fluvial geomorphological channel stabilization practices, there are now a
number of different types of channel modifications that can be implemented in one watercourse
to accomplish hazard mitigation objectives, while improving the overall health and ecology of the
stream. However, much like bridge and culvert modifications, precautions must be taken to
ensure that downstream flooding problems are not exacerbated by an upstream channel
modification. In addition, long-term channel maintenance can be just as important as the onetime
channel modification/diversion project. As such, the Mitigation Steering Committee identified
the following Structural Project Hazard Mitigation Measures to be implemented within the
County.
SP-6:
SP-7:
Support the recommendations of, and assist in implementing the
Lower Paxton Creek Revitalization Project.
Develop and implement a community-specific channel maintenance
program consisting of routine inspections and subsequent
debris removal to ensure maximum hydraulic capacity of all local
streams and watercourses.
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5.1.4.4 Firebreaks
Firebreaks have been used by the PA DCNR and the Pennsylvania Game Commission
across the State to limit the mobility of potential wildfires. Construction of a firebreak involves
removing vegetation in a linear strip to significantly diminish the available fuel load. Coordination
with the PA DCNR Weiser Forest District Forest Fire Specialist Supervisor indicated that
there is one primary location in the County where construction of a firebreak may prove to be a
feasible and prudent wildfire hazard mitigation measure. This area is located on the south side
of Peters Mountain in Rush Township along Route 325. At this location, there is a rural development
containing approximately 30 residential structures in a mountainous and forested setting
with only one access road. This type of development scenario is particularly susceptible to
wildfire hazards. As such, the Mitigation Steering Committee identified the following Structural
Project Hazard Mitigation Measure for potential implementation within the County.
SP-8:
Coordinate with the PA DCNR Weiser Forest District and the Pennsylvania
Game Commission on the potential construction of a firebreak
at the appropriate location on the south side of Peters Mountain
along Route 325 in Rush Township.
5.1.4.5 Sinkhole Abatement
As previously mentioned, a portion of the County (see Figure 2-4) is underlain by carbonate
geology and is susceptible to the formation of sinkholes. Sinkholes form when carbonate
bedrock is dissolved by naturally-occurring atmospheric carbonic acid. Sinkholes have
the potential to result in significant structural damage and are a major concern for many property
owners. In an ideal situation, sinkholes would occur in undeveloped rural areas where they
would result in little to no surface damage. Unfortunately, this is not always the case in Dauphin
County and structural abatement must sometimes be employed. Therefore, structural sinkhole
abatement has been included in this hazard mitigation plan because it is the primary method of
dealing with a sinkhole after one has been exposed at the ground surface.
Sinkhole abatement is the physical treatment of new and existing sinkholes in an effort
to minimize potential damage to buildings, infrastructure and other surface features. Sinkhole
abatement involves filling the surface feature with a mixture of materials including concrete, soil,
grout, synthetic filter fabrics, and various sizes of crushed stone. Since no two sinkholes are
alike, abatement can vary significantly in the type and volume of materials that are used.
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Regardless of the size and nature of the sinkhole, however, certain precautions should be taken
when dealing with structural sinkhole abatement. These precautions, which are designed to
reduce safety concerns and mitigate potential environmental impacts, include barricading the
site to prevent personal injury, excavating the overlying soil to determine the appropriate
abatement method and to expose a competent limestone ledge, and directing surface drainage
away from the site to prevent a reoccurrence. Given these relatively inexpensive and potentially
life-saving precautionary steps, the Mitigation Steering Committee identified the following
Structural Project Hazard Mitigation Measures to be implemented within the County.
SP-9:
Implement the suggested precautionary steps when using structural
abatement techniques (recommended to be identified by a
registered Professional Geologist or other acceptable expert) to
remedy surface-exposed sinkhole features.
SP-10: Require expert technical assistance and establish mandatory
timeframes for structurally abating surface-exposed sinkhole features
that pose an identifiable threat to the general public.
5.1.4.6 Landslide Abatement
Landslide abatement can range from physically scaling a rock slope to installing slope
stabilizing wire mesh and protective fencing. According to Dauphin County’s hazard identification
and risk assessment data (see Figure 2-4) there is only one known/reported landslide
hazard area in the County. This landslide hazard area is located in a steep roadway cut along
Route 147 north of Millersburg in Upper Paxton Township. At this location, loose materials have
been reported to enter the roadway from the adjacent slope. Any location that results in debris
entering the roadway presents a potential danger to the traveling public. Installation of protective
fencing at this location would minimize this potential public threat. As such, the Mitigation
Steering Committee identified the following Structural Project Hazard Mitigation Measure to be
implemented in the County.
SP-11: Coordinate with PennDOT and the DCCD to determine the feasibility
of erecting protective fencing in the known landslide hazard area
along Route 147 north of Millersburg in Upper Paxton Township.
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5.1.4.7 Emergency Water Source Development
Within Dauphin County, there are numerous municipalities that lack a public water
supply system and the associated curbside hydrants for local fire fighting needs. Therefore,
many local fire companies must use tanker trucks and remote water supply sites to fight fires.
As such, quick and easy access to reliable water sources and the ability to efficiently pump
water from those sources is a critical issue for a number of Dauphin County’s fire companies.
Generally, this concept is more important in the northern mountainous part of the County, as
opposed to the more urbanized southern part of the County. Coordination with the PA DCNR
Weiser Forest District Forest Fire Specialist Supervisor and DEMA indicated that there is a
general need for additional emergency water supply sources for fire fighting uses in the northern
part of the County. This need could be most easily fulfilled through the installation of dry
hydrants at various bridge and culvert crossings of local streams and watercourses. A dry
hydrant (see Figure 5-7) is a non-pressurized pipe system permanently installed in existing
lakes, ponds and streams that provides a suction supply of water to a fire department tank truck.
FIGURE 5-7
A TYPICAL DRY HYDRANT
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Dry hydrants provide an easily accessible and reliable source of water for pumping in times of
emergency need. As such, the Mitigation Steering Committee identified the following Structural
Project Hazard Mitigation Measure for implementation within the County.
SP-12: Install easily accessible and reliable water supply dry hydrants at
various bridge and culvert crossings of local streams and watercourses
for emergency fire fighting uses through coordination with
the PA DCNR and local fire companies.
5.1.4.8 Additional, Updated, and Obsolete Mitigation Measures
For the update process, the Mitigation Steering Committee reviewed the original mitigation
measures and determined those which may need modified, those which are now obsolete,
and those which need to be added. SP-11 has now become obsolete. The project was completed
by Upper Paxton Township in the Summer of 2008
5.1.5 Natural Resource Protection
Natural resource protection activities that are implemented as hazard mitigation
measures can be multiple in scope, purpose, and outcome. They are generally aimed at
preserving (or in some cases restoring) local natural areas, environmentally sensitive resources,
or the overall quality of some locally significant feature but can also play a significant role in
reducing local and regional damages caused by natural hazard events. Natural resource
protection activities are typically implemented by park, recreation, or conservation agencies and
organizations but are not limited to these types of entities. Any responsible entity, such as a
local government, can develop and implement a natural resource protection program that will
minimize the impacts of natural hazards while enhancing the local and regional environment.
Natural resource protection activities that can minimize the potential impacts of natural hazards
include the following:
open space preservation;
wetland protection;
identification and implementation of Best Management Practices (BMPs);
and
water resources management planning.
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Implementation of natural resource protection activities of this nature will work towards the fulfillment
of the following project-planning goals as identified by the Mitigation Steering Committee.
Preserve areas where natural hazard potential is high (i.e., steeply sloping
areas, sinkhole areas, floodplains, wetlands, etc.).
Minimize future damage due to flooding of the Susquehanna River and its
tributaries.
Reduce impacts related to flash flooding and stormwater problems.
Regulate construction/development in the County to prevent increases in
runoff and subsequent increases in floodflows.
Protect existing natural resources and open space, including parks and
wetlands, within the floodplain.
Restore degraded natural resources and open space to improve their
flood-control function.
Ensure the adequacy of erosion and sedimentation control practices
throughout the County.
Reduce threats related to wildfires.
Reduce threats related to landslides.
Minimize crop damage due to drought situations.
5.1.5.1 Open Space Preservation
Keeping known hazard areas free of development and in a natural condition is the best
approach to minimizing or preventing potential damages. In regard to Dauphin County, this
concept is applicable to natural hazards like flooding, landslides, and wildfires where floodplain,
steep slope, and forested area preservation (respectively) can effectively minimize the County’s
susceptibility to potential damage. Preserving open space in an undeveloped floodplain not
only prevents potential flood damage but also allows for the full realization of the floodplain’s
natural and beneficial functions. These natural and beneficial floodplain functions include floodwater
storage/floodflow attenuation, surface water infiltration/groundwater recharge, removal/
filtering of pollutants and sediments from floodwater, habitat for flora and fauna, and recreational
opportunities. Similarly, keeping development away from steep slopes and extensive forested
areas not only prevents potential damage but also provides valuable habitat for many plant and
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animal species and the potential for increased recreational opportunities. As previously mentioned,
open space preservation can be accomplished locally through the adoption and enforcement
of various ordinance provisions (see PM-1, PM-2, and PM-12) but can also be
accomplished through property acquisition and easement. As such, the Mitigation Steering
Committee identified the following Natural Resource (NR) Protection Hazard Mitigation
Measures to be implemented within the County.
NR-1:
NR-2:
NR-3:
NR-4:
Conduct a detailed inventory and prioritization of local environmental
resources via the Comprehensive Planning or similar natural
resources planning process.
Preserve the highest priority undeveloped floodplain areas via fee
simple acquisition and/or permanent easement and retain as public
open space for passive recreational uses in an effort to minimize/prevent
potential flooding damages and enhance the regional
environment. Less critical floodplain areas may be preserved/
protected via local ordinance (see PM-2 and PM-4).
Preserve the highest priority undeveloped steep slope areas via
fee simple acquisition and/or permanent easement and retain as
public open space for passive recreational uses in an effort to minimize/prevent
potential landslide damages and enhance the regional
environment. Less critical steep slope areas may be preserved/protected
via local ordinance (see PM-2 and PM-4).
Preserve critical undeveloped forested areas via fee simple acquisition
and/or permanent easement and retain as public open space
for passive recreational uses in an effort to minimize/prevent potential
wildfire damages and enhance the regional environment.
Implementation of conservation subdivision design principles, as
identified in PM-4, could be used to preserve other less critical forested
areas as deemed appropriate by the municipality.
5.1.5.2 Wetland Protection
Wetlands as defined by the PA DEP and the USACE are often found in floodplains and
depressional areas of a watershed. Many wetlands receive and store floodwaters, thus slowing
and reducing downstream flows. They also serve as a natural filter, which helps to improve
water quality and provide habitat for many species of fish, wildlife, and plants. Wetlands are
regulated by the USACE under Section 404 of the Clean Water Act and by PA DEP under
Chapter 105 of Pennsylvania’s Dams Safety and Encroachment Act. Federal and state permits
are required for projects that will impact wetlands. Before a permit is issued, the plans are
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eviewed by several agencies, including the USACE, PA DEP, U.S. Fish and Wildlife Service,
and U.S. Environmental Protection Agency. If a permit is issued, the wetland impact is typically
required to be mitigated. Wetland mitigation can include creation, restoration, enhancement, or
preservation of wetlands. The appropriate type of mitigation is addressed in each independent
permit action. Even with this federal and state protection, many wetlands (particularly smaller
ones) continue to be impacted due to gaps (i.e., unregulated activities) in the federal and state
regulations. As such, local wetland protection programs can be developed to address these
gaps in the federal and state regulations. Given the local and regional importance of wetlands,
the Mitigation Steering Committee identified the following Natural Resource Protection Hazard
Mitigation Measures to be implemented within the County.
NR-5:
NR-6:
Preserve high priority wetland areas (see NR-1) via fee simple acquisition
and/or permanent easement and retain as public open
space for passive recreational uses in an effort to minimize potential
flooding damages and enhance the regional environment.
Develop and implement a wetland protection program consisting
of public education materials that highlight the functions and values
of wetlands and local ordinance provisions that require the
identification of wetlands in accordance with federal and state
standards and minimize/eliminate their disturbance in accordance
with federal and state laws.
5.1.5.3 Identification and Implementation of Best Management Practices
Best management practices (BMPs) are measures that reduce the volume of surface
water runoff and associated non-point source pollutants from entering waterways. Non-point
source pollutants are transported by surface water runoff and include lawn fertilizers, pesticides,
farm chemicals, sediments, and oils from both pervious and impervious urban and rural areas.
Non-point source pollutants not only affect the quality of our local water resources but also their
ability to carry and store floodwaters. Eroded soil from farmlands and construction sites is
typically deposited where streams and rivers slow down and lose energy, such as when they
enter a lake or confluence with another stream. As such, sedimentation will gradually fill in
channels and lakes, reducing their ability to carry or store floodwaters. In addition, uncontrolled
surface water runoff contributes to local and regional flooding problems.
From a hazard mitigation perspective, the identification and implementation of BMPs is
focused on structural and non-structural erosion and sedimentation control and stormwater
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management facilities. Many BMP measures (structural and/or non-structural) can be implemented
on a site to address specific site needs. Both erosion and sedimentation control and
stormwater management BMPs can be incorporated into retention and detention basins, drainageways,
and many other parts of new developments. Depending on local ordinances, specific
BMPs and structural measures may already be required on industrial sites, mined lands, construction
sites, farms, forested areas, and high-use public lands.
As previously mentioned, the DCCD is very active in the completion of watershedspecific
stormwater management plans in accordance with Pennsylvania’s Stormwater Management
Act (Act 167 of 1968). These stormwater management plans and associated stormwater
management ordinances typically include provisions for local implementation of stormwater
management BMPs. As such, effective completion of PM-7 would, by default, result in
the identification and implementation of stormwater management BMPs at the local level.
Therefore, the identification and implementation of BMPs as a natural resource protection
hazard mitigation measure must be focused on erosion and sedimentation control practices on
construction sites, farms, and other large disturbed areas. Fortunate for Dauphin County is the
fact that the Conservation District has several erosion and sedimentation control technicians
who monitor construction sites to ensure contractor compliance with the approved Erosion and
Sedimentation Pollution Control Plan and work with local farmers to implement erosion and
sedimentation control BMPs. As such, the Mitigation Steering Committee recognized the
DCCD’s existing efforts to control erosion and sedimentation and identified continued implementation
of these efforts as a Natural Resource Protection Hazard Mitigation Measure for the
County.
NR-7:
Working through the Conservation District, the County should ensure
continued contractor compliance with approved Erosion and
Sedimentation Pollution Control Plans and should continue to
work with local farmers to implement erosion and sedimentation
control BMPs.
5.1.5.4 Water Resources Management Planning
Comprehensive water resources management planning is a topic that has gained
increased attention over the past several years due to the alarming frequency and severity of
recent drought events. The importance of water as a critical life-sustaining natural resource is
never more realized than during a water supply shortage caused by a severe drought event.
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Within Pennsylvania, the Water Resources Planning Act (Act 220 of 2002) was passed to help
mitigate the potentially devastating effects of Pennsylvania’s drought hazard. The Act requires
the State Water Plan (a document that analyzes existing and future water resources supply and
demand) to be updated within five years and every five years thereafter. It is anticipated that
the updated State Water Plan will identify Critical Water Planning Areas where water use
demand exceeds or is expected to exceed available water resources supply, in which case,
more detailed water resources planning would be completed. At this point in time, it is not
known if Dauphin County, or any area in Dauphin County, will be identified as a Critical Water
Planning Area. However, given 1) the County’s role as home to the State Capitol and a significant
portion of the state’s governmental infrastructure, 2) the presence of the City of Harrisburg
and intensely developed surrounding area, and 3) the County’s intense and varied (i.e., residential,
commercial, industrial, agricultural, etc.) demand for potable water resources, the development
and implementation of a comprehensive water resources management plan would be an
appropriate activity for the County to engage in to help mitigate the potentially devastating
effects of severe drought events. To date, there have been four studies relating to water supply
for Dauphin County:
Dauphin County 1969 Water Supply Plan
1992 Harrisburg Metropolitan Regional Water Supply Study, including
Harrisburg City and parts of Dauphin, Cumberland, Berks, Franklin, Perry
and York Counties. The plan concluded that “the large systems appear to
have effectively anticipated growth and that “the area has abundant water
and adequate infrastructure to treat and distribute this water and that
there is no pressing need to regionalize the large systems in order to
meet demand.”
Lower Susquehanna Comprehensive Water Resources Study – Only
Phase 1 (data collection) has been completed for 13 watersheds in 8
counties, including part of Dauphin County
Swatara Creek Watershed Water Supply Study (2003) – This plan includes
most of Lebanon County and portions of Berks, Dauphin, and
Schuylkill Counties. The study found that Pennsylvania American Water
– Hershey District may experience a small shortage of water in 2030.
The Dauphin County Comprehensive Plan, which is currently being updated, references these
studies and identifies the need to update the County-wide Water Supply Plan. As such, the
Mitigation Steering Committee identified the following Natural Resource Protection Hazard
Mitigation Measure to be implemented within the County.
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NR-8: Update and implement a comprehensive water resources management
plan that analyzes the County’s existing water resources
supply and evaluates the County’s anticipated water use demand
in an effort to identify suspected water supply shortages and potential
new water supply sources.
5.1.5.5 Additional, Updated, and Obsolete Mitigation Measures
For the update process, the Mitigation Steering Committee reviewed the original mitigation
measures and determined those which may need to be modified, those which are now
obsolete, and those which need to be added. For Natural Resource Measures, there have been
no new or updated measures which were deemed necessary. The Committee also felt that all
of the above measures should stay in place.
5.1.6 Public Information
Providing the public with accurate and relevant information is a key component of a
successful hazard mitigation program. Public information activities advise residents, business
owners, and local officials about natural hazards and ways they can protect themselves, their
property, and their constituents from these hazards. Public information activities can be aimed
at the entire County or at select residents and business owners in known hazard areas. These
programs are intended to motivate people to take precautionary steps on a pre-disaster basis.
Within Dauphin County, the Public Relations Office has sole responsibility for public
information dissemination. As such, all hazard mitigation related public information activities
should be coordinated and implemented through this office. These public information activities
include the following:
map information;
library resources;
outreach projects; and
environmental education.
Implementation of public information measures of this nature will work towards the fulfillment of
the following project-planning goals as identified by the Mitigation Steering Committee.
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Ensure that all residents and business owners are aware of the potential
hazards associated with their environment and the ways they can protect
themselves.
Ensure that property owners and potential property owners are aware of
the availability and benefits of obtaining federal flood insurance.
Ensure that local officials are well trained regarding natural hazards and
appropriate prevention and mitigation activities.
Develop citizen information on natural, technological, and man-made disaster
response.
Increase the length of stream reaches mapped on FIRM maps and/or increase
the occurrence of flood elevation data where this future mapping
would be beneficial.
Improve the participation rate in federal flood insurance through education.
5.1.6.1 Map Information
Many benefits stem from providing flood hazard map information to inquirers. Residents
and business owners who are aware of potential flood hazards can take steps to avoid problems
and/or reduce their exposure to flooding. Real estate agents and potential homebuyers
can determine if a particular property is located in a known flood hazard area and whether flood
insurance may be required. Even with the passage of Pennsylvania Act 84 of 1996 (which
requires the seller of any residential real estate to complete a mandatory property disclosure
statement) it is still important for potential buyers to review the community’s flood insurance rate
mapping to ensure that their prospective property is not located in a floodplain. It is important to
remember, however, that flood maps are not perfect; they display only the larger flood-prone
areas that have been studied. Some maps are based on data that are more than 20 years old.
In some areas, watershed developments make even recent maps outdated. As such, in addition
to Preventive Measure 3 (PM-3) related to the sharing of the multi-hazard mapping from this
plan for municipal planning and information purposes, the Mitigation Steering Committee
identified the following Public Information (PI) Hazard Mitigation Measures to be implemented
within the County.
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PI-1:
PI-2:
Coordinate with FEMA and the PA DCED regarding updating Dauphin
County’s Flood Insurance Rate Mapping via FEMA’s Flood
Map Modernization Program to include the expansion of previously
unmapped areas and additional Base Flood Elevations (BFEs).
Municipalities should store in an easily accessible location and
make available for public inspection, their community’s Flood Insurance
Rate Mapping and associated Flood Insurance Study.
Dauphin County could provide copies of these maps at the courthouse
and/or conservation district offices and/or scan and post
current maps on their Web site for all communities or those unable
to provide information on their own Web site.
5.1.6.2 Library Resources
Local libraries (i.e., the Dauphin County Library System - http://www.dcls.org/) are an
obvious place for residents to seek information on natural hazards and natural hazard mitigation.
The community library is usually the first place people turn when researching a topic.
Interested property owners can read or check out handbooks or other publications that cover
their particular situation. Additionally, libraries typically offer Internet access, which can be used
to find a wealth of information on just about any topic, including hazard mitigation. For example,
FEMA’s Web site at http://www.fema.gov/ is not only user friendly, but also contains great
information for homeowners, engineers, lenders, and other interested citizens. Libraries also
have public information campaigns with displays, lectures and other projects, which could
augment the County’s natural hazard mitigation activities. In addition, municipalities can keep
their own library of hazard-related resources as a public service for their constituents. As part of
this hazard mitigation planning program, various FEMA guidance documents were provided to a
number of the County’s municipalities for public information purposes. As such, the Mitigation
Steering Committee identified the following Public Information Hazard Mitigation Measures to be
implemented within the County.
PI-3:
PI-4:
Maintain natural hazard risk assessment and mitigation publications/materials
at public libraries throughout the County.
Store in an easily accessible location and make available for public
inspection, this hazard mitigation plan and the FEMA guidance
documents that were provided as part of the hazard mitigation
planning program.
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5.1.6.3 Outreach Projects
Map information and library resources are not of much use if no one knows they exist.
An outreach program can remedy this. Sending notices to hazard-prone property owners can
introduce the idea of property protection and identify sources of assistance. Outreach programs
are the first step in the process of orienting property owners to property protection measures
and assisting them in designing and implementing a project. These programs are designed to
encourage people to seek out more information and take steps to protect themselves and their
properties. An outreach project can be a notice that is mailed or otherwise distributed to hazard-prone
property owners and/or an article in a newsletter or local newspaper that will reach
local residents. Other approaches can include the following:
displays in public buildings or shopping malls;
radio and TV news releases and interview shows;
presentations at meetings or relevant local organizations;
floodproofing open houses; and
Web site notices with hyperlinks to other sources of information.
Research has proven that outreach projects work. However, awareness of the hazard is
not enough; people need to know what they can do in preparation for, during and after a hazard
event. Public outreach programs should include information on property protection measures,
safety procedures, and post disaster clean-up tips. Outreach projects should also be locally
designed and run so the public recognizes the relevance to their specific needs and local
conditions. As such, the Mitigation Steering Committee identified the following Public Information
(PI) Hazard Mitigation Measures to be implemented within the County.
PI-5:
PI-6:
Develop and distribute a public summary of this hazard mitigation
plan including relevant information on hazard specific “do’s” and
“don’ts,” hazard-prone areas, emergency contact information, and
lists of shelters or hotels where evacuees can stay with domestic
animals.
Develop and implement a post-disaster recovery and mitigation
training program for local officials (see ES-14 and ES-15).
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PI-7:
Create a Web site links/references section on the Dauphin County
and/or DEMA Web site homepage to include links to FEMA -
http://www.fema.gov/, PEMA - http://www.pema.state.pa.us/, PA
DCED - http://www.inventpa.com/, and NWS - http://www.nws.
noaa.gov/. Additional links could also include those for watershed
associations, the SRBC - http://www.srbc.net/, DCCD - http://www.
dauphincd.org/main/welcome.php, and TCRPC - http://www.tcrpcpa.org/.
5.1.6.4 Environmental Education
Environmental education programs can teach people about natural hazards, the factors
that cause them, and the significance of avoiding known hazard areas. These programs can be
undertaken by municipalities, schools, park and recreation departments, conservation associations,
and youth organizations such as the Boy Scouts/Girl Scouts, Campfire Girls, and summer
camps. An activity can be as involved as course curriculum development or as simple as an
explanatory sign near a river. The more educated people are about natural hazards, the less
likely they will be to reside in known hazard areas. As such, the Mitigation Steering Committee
identified the following Public Information Hazard Mitigation Measure to be implemented within
the County.
PI-8:
Coordinate with FEMA, PEMA, PA DCED, NWS, the DCCD and any
other appropriate entities on developing and implementing a natural
hazard awareness curriculum in local schools.
5.1.6.5 Additional, Updated, and Obsolete Mitigation Measures
For the update process, the Mitigation Steering Committee reviewed the original mitigation
measures and determined those which may need to be modified, those which are now
obsolete, and those which need to be added. PI-1 has become obsolete due to the updated
FIRM’s that FEMA is scheduled to release. PI-4 has been modified to include the plan update
and is now PI-9, and a new PI-10 has been added which read as follows:
PI-9:
Store in an easily accessible location and make available for public
inspection, the original hazard mitigation plan, the new plan update
document, and the FEMA guidance documents which were provided
as part of the hazard mitigation planning program. Also make
electronic files available for review.
PI-10:
Develop the county’s GIS system to include an updated and fully
attributed building/structure coverage by use and type.
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5.2 IMPLEMENTATION OF HAZARD MITIGATION MEASURES
5.2.1 Hazard Mitigation Action Plan
Table 5-8 has been developed to summarize and prioritize the identified hazard mitigation
measures. This table lists the individual action items as being high-, medium-, or lowpriority
hazard mitigation measures for the County. The Mitigation Steering Committee prioritized
these projects from an overall County perspective based on their individual ability to fulfill
the identified project-planning goals (see Chapter 3) and their relative hazard mitigation/
protection afforded. To assist in this prioritization, the Mitigation Steering Committee established
criteria for evaluating and comparing the subject projects. These County-level project
prioritization evaluation criteria were used to rank the projects as being high-, medium-, or lowpriority.
The prioritization evaluation criteria include the following.
Perceived and/or calculated benefit-cost ratio
Number of hazards addressed (i.e., single- or multi-hazard)
Number of people the project would benefit
Frequency of impact (i.e., repetitive losses)
Severity of impact
Longevity/permanence of the project
Permanent residence vs. seasonal residence
Human impacts v. property impacts (i.e., potential for loss of life)
Potential for economic losses
Preventive value
Implications of the impact
It is recognized that the overall county-level prioritization for any given project may not
be entirely applicable at the municipal implementation level. Municipalities are likely to find that
their individual needs/circumstances warrant a re-prioritization of the recommended action items
to more appropriately address local conditions. This concept is perfectly acceptable and is
expected to occur following local adoption of the plan. In general, high-priority projects are to be
implemented within the first five years following plan adoption, pending availability of project
funding. Medium-priority projects are to be implemented within five to seven years following
plan adoption, pending availability of project funding, or upon completion of the high-priority
projects. Similarly, low-priority projects are to be implemented within seven to ten years following
plan adoption, pending availability of project funding, or upon completion of the high-and
medium-priority projects.
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TABLE 5-8
PRIORITIZED HAZARD MITIGATION ACTION PLAN
PROJECT
ID
PROJECT DESCRIPTION RESPONSIBLE ENTITY POTENTIAL GRANT FUNDING SOURCES
High-Priority
DATE OF
COMPLETION
PM-1
PM-3
PM-6
PM-7
PM-8
PM-12
ES-6
ES-7
ES-8
ES-9
ES-10
ES-13
ES-18
Develop a new, or amend an existing, Comprehensive Plan to
include an assessment of hazard vulnerability and appropriate
mitigation recommendations
Make available for municipal use the digital natural hazard
mapping files that were developed as part of this planning study TCRPC
Ensure municipal compliance with minimum NFIP and PA Act
166 floodplain development regulations
Ensure municipal compliance with local watershed-specific Act
167 Stormwater Management Plans
Ensure continued implementation of appropriate operations and
maintenance procedures at the DeHart Dam
Revise or re-adopt a municipal floodplain management
ordinance that is consistent with revised FEMA floodplain
mapping to ensure municipal compliance with NFIP and PA Act
166 floodplain development regulations, as appropriate.
Conduct routine inspections, regular maintenance, and annual
tests on all emergency communications equipment, public
address systems, and hazard alert sirens to ensure unhindered
operation during an emergency event
Ensure that a planned, coordinated, and effective public
warning dissemination program exists at the local level
Adopt via resolution, and respond to hazards with actions that
consistent with, the County-level EOP
Conduct hazard response practice drills and emergency
management training exercises on an annual basis
Encourage the owners/operators of the Yeshiva Academy, the
Riverside Elementary School, the Downey Elementary School,
the Harrisburg Area Community College, the Circle School, and
the Williams Twp. Wastewater Treatment Plant to develop and
implement and emergency response plan
Conduct rigorous sampling and analysis of public and private
drinking water supply sources immediately after an inundating
flood event and issue boil water advisories as needed
Encourage the owners/operators of Yeshiva Academy, Downey
Elementary School, Circle School, and the Williams Township
Wastewater Treatment Plant to develop and implement an
emergency response plan to mitigate potential flooding impacts.
County – TCRPC
Local – Municipal Staff/Officials
Municipal Staff/Officials with technical assistance
from the DCED
Municipal Staff/Officials with technical assistance
from the DCCD and/or PA DEP
Harrisburg City Water Bureau
Municipal officials
County – Dauphin County EMA
Local - Municipal EMCs
Municipal EMCs with technical assistance from the
Dauphin County EMA
Municipal Officials/EMCs
Dauphin County EMA
County – Dauphin County EMA
Local - Municipal Staff/Officials
Public Water Suppliers and Property Owners
Municipal officials, property owners, and Dauphin
County EMA
DCED’s Land Use Planning and Technical Assistance
Program
N/A
DCED’s Floodplain Land Use Assistance Program
PA DEP’s Stormwater Management Planning Program
N/A
DCED’s Floodplain Land Use Assistance Program
N/A
N/A
N/A
N/A
N/A
N/A
N/A

TABLE 5-8
PRIORITIZED HAZARD MITIGATION ACTION PLAN
(CONTINUED)
PROJECT
ID
PROJECT DESCRIPTION RESPONSIBLE ENTITY POTENTIAL GRANT FUNDING SOURCES
ES-19 Solicit funds in order to continue the operation of river gauges. Dauphin County EMA, DCCD, and SRBC U.S. ACE/PA DEP CWA Fund
ES-20
ES-21
ES-24
ES-25
PP-1
PP-2
PP-3
PP-4
PP-5
SP-1
SP-6
Encourage citizens, schools, nursing homes, hospitals, etc., to
sign up for AlertPA notifications.
Develop flood forecasting maps for the Harrisburg area.
Establish an alternate EOC location in the event the primary
EOC must be evacuated. The facility should be selected to
support the EOC as well as all of the County Special Teams.
This facility should also be located outside of the TMI EPZ and
100-year floodplain areas.
Encourage Dauphin County EOC and municipal EOC’s
(including those outside the TMI EPZ) to participate in more
exercises and evacuation drills to practice and gain efficiency in
emergency plan preparedness.
Relocate and/or acquire known flood-prone structures in
accordance with the general guidelines of Table 5-3
Elevate known flood-prone structures in accordance with the
general guidelines of Table 5-3
Dry floodproof known flood-prone structures in accordance with
the general guidelines of Table 5-3
Wet floodproof known flood-prone structures in accordance with
the general guidelines of Table 5-3
Encourage uninsured property owners in known flood hazard
areas to purchase flood insurance through the NFIP
Investigate the feasibility of constructing a levee/floodwall
system and/or a floodwater storage reservoir along Rattling
Creek, Bear Creek and/or Wiconisco Creek to
minimize/eliminate Lyken’s Borough’s extensive flood hazard
potential
Support the recommendations of, and assist in implementing
the Lower Paxton Creek Revitalization Project.
Municipal officials, Dauphin County EMA, and
property owners
Harrisburg City, Dauphin County EMA, SRBC, and
USACE
N/A
Municipal officials and Dauphin County EMA PA Act 147
Municipal officials and Dauphin County EMA PA Act 147
Joint effort between Municipal Officials/Staff and
Local Property Owners
Joint effort between Municipal Officials/Staff and
Local Property Owners
Joint effort between Municipal Officials/Staff and
Local Property Owners
Joint effort between Municipal Officials/Staff and
Local Property Owners
Agency – FEMA/PEMA/DCED
County – Dauphin County Public Relations Office
Local – Municipal Officials/Staff
Agency – FEMA/COE/PA DEP
Local – Municipal Staff/Officials
Agency – FEMA/COE/PA DEP
County – Dauphin County Commissioners/DCCD
Local – Municipal Officials
FEMA’s Cooperating Technical Partners Program
FEMA’s Pre-Disaster/Hazard Mitigation Grant Program
FEMA’s Flood Mitigation Assistance Program
HUD’s Disaster Recovery Initiative
FEMA’s Pre-Disaster/Hazard Mitigation Grant Program
FEMA’s Flood Mitigation Assistance Program
HUD’s Disaster Recovery Initiative
FEMA’s Pre-Disaster/Hazard Mitigation Grant Program
FEMA’s Flood Mitigation Assistance Program
HUD’s Disaster Recovery Initiative
FEMA’s Pre-Disaster/Hazard Mitigation Grant Program
FEMA’s Flood Mitigation Assistance Program
HUD’s Disaster Recovery Initiative
N/A
U.S. ACE’s Continuing Authorities Program
PA DEP’s Flood Protection Program
U.S. ACE PA DEP Growing Greener Watershed Protection
Program
DATE OF
COMPLETION

TABLE 5-8
PRIORITIZED HAZARD MITIGATION ACTION PLAN
(CONTINUED)
PROJECT
ID
NR-1
NR-2
PI-1
PI-2
PI-3
PI-4
PI-5
PI-6
PROJECT DESCRIPTION RESPONSIBLE ENTITY POTENTIAL GRANT FUNDING SOURCES
Conduct a detailed inventory and prioritization of local
environmental resources via the Comprehensive Planning or
similar natural resources planning process
Preserve the highest priority undeveloped floodplain areas via
fee simple acquisition and/or permanent easement and retain
as public open space for passive recreational uses. Less critical
floodplain areas may be preserved/protected via local ordinance
(see PM-2 and PM-4).
Coordinate with FEMA and the DCED regarding updating
Dauphin County’s Flood Insurance Rate Mapping via FEMA’s
Flood Map Modernization Program to include the expansion of
previously unmapped areas and additional Base Flood
Elevations
Store in an easily accessible location and make available for
public inspection, the community’s Flood Insurance Rate
Mapping and associated Flood Insurance Study
Maintain natural hazard risk assessment and mitigation
publications/materials at public libraries throughout the County
Store in an easily accessible location and make available for
public inspection, this hazard mitigation plan and the FEMA
guidance documents that were provided as part of the hazard
mitigation planning program
Develop and distribute a public summary of this hazard
mitigation plan including relevant information on hazard-prone
areas, hazard specific “do’s” and “don’ts” and emergency
contact information
Develop and implement a post-disaster recovery and mitigation
training program for local officials (see ES-14 and ES-15).
Municipal Officials/Staff with technical assistance
from the TCRPC, DCCD, PA DCNR, and PA DEP
County – Dauphin County Parks Department
Local – Municipal Officials
Joint effort between the TCRPC and the DCCD
with technical assistance from FEMA/SRBC and
DCED
County – Dauphin County Public Relations
Office/DCCD
Local – Municipal Staff/Officials
Dauphin County Public Library System
County – Dauphin County Public Relations
Office/DCCD/TCRPC
Local – Municipal Staff/Officials
Dauphin County Public Relations Office
Dauphin County EMA with technical assistance
from PEMA/FEMA
PA DCNR Community Conservation Partnership Program
PA DCNR’s Community Conservation Partnership Program
PA DCNR’s Pennsylvania Greenways Initiative
DATE OF
COMPLETION
FEMA’s Flood Map Modernization Program September 2009
N/A
N/A
N/A
FEMA’s Pre-Disaster Mitigation Grant Program
FEMA’s Pre-Disaster Mitigation Grant Program PEMA
PM-2
PM-4
Develop a new, or revise an existing, Zoning Ordinance to
include separate zones or districts for known hazard areas
Develop a new, or revise an existing, Subdivision and Land
Development Ordinance to include municipality-specific, hazard
mitigation-related development criteria and/or provisions for the
mandatory use of conservation subdivision design principles
Municipal Staff/Officials
Medium-Priority
County – TCRPC
Local – Municipal Staff/Officials
DCED’s Land Use Planning and Technical Assistance
Program
DCED’s Floodplain Land Use Assistance Program
DCED’s Land Use Planning and Technical Assistance
Program

PROJECT
ID
PM-9
PM-10
TABLE 5-8
PRIORITIZED HAZARD MITIGATION ACTION PLAN
(CONTINUED)
PROJECT DESCRIPTION RESPONSIBLE ENTITY POTENTIAL GRANT FUNDING SOURCES
Revise existing zoning and/or subdivision and land development
ordinances or adopt a separate, stand-alone ordinance to
require the completion of subsurface investigations for all new
subdivision and land development project in known land
subsidence areas.
Implement a wildfire-prevention public education program
consisting of the development and distribution of an informative
brochure and training for local officials on PA’s Firewise
Communities Program
Municipal Staff/Officials
Dauphin County EMA with technical assistance
from the PA DCNR
PM-11 Enroll in the PA Firewise Communities Program Municipal Staff/Officials
ES-1
ES-4
ES-5
ES-12
ES-14
ES-15
ES-16
ES-17
Establish a partnering relationship with the NWS Mid-Atlantic
River Forecast Center to enhance the existing Susquehanna
River Basin Flood Forecast and Warning System via the
Advanced Hydrologic Prediction Services Program
Consider expanding the City of Harrisburg’s automated
emergency alert community calling system to the County-level
Provide alphanumeric pagers to local emergency management
coordinators as a means of improving the County’s warning
dissemination program
Develop and distribute a public informational pamphlet related
to the potential health and safety implications of various natural
hazard events
Develop a technical proficiency at the municipal level for
conducting post-disaster damage assessments and regulating
reconstruction activities to ensure compliance with NFIP
substantial damage/improvement requirements
Develop a technical proficiency at the municipal level for
assisting local residents and business owners in applying for
hazard mitigation/assistance funds and identifying cost
beneficial mitigation measures to incorporate into reconstruction
activities
Increase the number of NOAA Weather Alert radios in public
places across the county which currently do not have them
(such as personal care homes) above and beyond what is
required of the County by the NWS’s Storm Ready Program.
Make the Reverse 911 automated emergency alert system fully
operational within the county.
Dauphin County EMA with technical assistance
from PEMA and/or the SRBC
Joint effort between Harrisburg City and the
Dauphin County EMA
DCED’s Land Use Planning and Technical Assistance
Program
N/A
FEMA’s Pre-Disaster Mitigation Grant Program PA DCNR’s
Firewise Program
U.S. ACE’s Floodplain Management Services Program
U.S. ACE’s Floodplain Management Services Program
DATE OF
COMPLETION
Dauphin County EMA and/or Municipal Officials N/A 2004
Dauphin County Public Relations Office with
technical assistance from PEMA and/or FEMA
Municipal Staff/Officials
County – Dauphin County EMA
Local - Municipal Staff/Officials
Dauphin County EMA
Dauphin County EMA
U.S. ACE’s Floodplain Management Services Program
DCED’s Floodplain Land Use Assistance Program
PEMA
NWS’s Storm Ready Program
TBD

TABLE 5-8
PRIORITIZED HAZARD MITIGATION ACTION PLAN
(CONTINUED)
PROJECT
ID
ES-22
ES-23
PP-6
PP-7
PP-8
SP-7
SP-12
NR-3
NR-4
NR -5
PROJECT DESCRIPTION RESPONSIBLE ENTITY POTENTIAL GRANT FUNDING SOURCES
Develop and/or obtain a program for the collection and
identification of Special Needs populations for means of
notification during an emergency. Also so that proper
transportation is provided to these populations in the event of an
evacuation.
Develop or obtain software programs to aid in resource
management and EOC management, as well as
communications to the regional and state task forces.
Encourage property owners in potential wildfire hazard areas to
remove all excess brush and shrubby plants from the immediate
vicinity (i.e., 50 to 100 feet) of all buildings
Encourage local business and industry owners in known flood
hazard areas to develop an emergency response plan as a
potential alternative to implementing a physical property
protection measure, where otherwise not technically or fiscally
appropriate
Educate and encourage uninsured property owners to purchase
flood insurance through the NFIP who are identified as being
located within the flood hazard areas on the new FEMA 100-
year floodplain mapping.
Develop and implement a community-specific channel
maintenance program consisting of routine inspections and
subsequent debris removal
Install easily accessible and reliable water supply dry hydrants
at various bridge and culvert crossings of local streams and
watercourses for emergency fire fighting uses
Preserve the highest priority undeveloped steep slope areas via
fee simple acquisition and/or permanent easement and retain
as public open space for passive recreational uses. Less
critical steep slope areas may be preserved/protected via local
ordinance (see PM-2 and PM-4).
Preserve critical undeveloped forested areas via fee simple
acquisition and/or permanent easement and retain as public
open space for passive recreational uses. Less critical forested
areas may be preserved/protected via local ordinance (see PM-
2 and PM-4).
Preserve high priority wetland areas via fee simple acquisition
and/or permanent easement and retain as public open space for
passive recreational uses. Less critical wetlands may be
preserved/protected via local ordinance (see PM-2 and PM-4).
Municipal officials and Dauphin County EMA
Dauphin County EMA
Agency – PA DCNR
Local – Municipal Staff/Officials
Municipal Staff/Officials
Municipal officials, Dauphin County EMA, DCED,
FEMA, PEMA, and SRBC
Municipal Staff/Officials
Municipal Staff/Officials with technical assistance
from the PA DCNR and local fire companies
County – Dauphin County Parks Department
Local – Municipal Officials
Agency – PA DCNR/PA Game Commission
County – Dauphin County Parks Department
Local – Municipal Officials
County – Dauphin County Parks Department
Local – Municipal Officials
TBD
TBD
N/A
N/A
FEMA’s Cooperating Technical Partners Program
DCED’s Floodplain Land Use Assistance Program
N/A
PA DCNR’s volunteer Fire Assistance Grant Program
Fire Commissioner VFCVAS Grant Program
PA DCNR’s Community Conservation Partnership Program
PA DCNR’s Pennsylvania Greenways Initiative
PA DCNR’s Community Conservation Partnership Program
PA DCNR’s Pennsylvania Greenways Initiative
PA DCNR’s Community Conservation Partnership Program
PA DCNR’s Pennsylvania Greenways Initiative
DATE OF
COMPLETION

TABLE 5-8
PRIORITIZED HAZARD MITIGATION ACTION PLAN
(CONTINUED)
PROJECT
ID
NR-8
PI-7
PI-9
PI-10
PROJECT DESCRIPTION RESPONSIBLE ENTITY POTENTIAL GRANT FUNDING SOURCES
Update and implement a comprehensive water resources
management plan that analyzes the County’s existing water
resources supply and evaluates the County’s anticipated water
use demand
Create a website links/references section on the Dauphin
County EMA website homepage to include links to FEMA,
PEMA, DCED, and the NWS
Store in an easily accessible location and make available for
public inspection, the original hazard mitigation plan, the new
plan update document, and the FEMA guidance documents
which were provided as part of the hazard mitigation planning
program. Also make electronic files available for review.
Develop the county’s GIS system to include an updated and
fully attributed building/structure coverage by use and type.
Joint effort between the TCRPC and the DCCD
with technical assistance from the SRBC and PA
DEP
Dauphin County Public Relations Office
Municipal officials, Dauphin County EMA, and
DCCD
Dauphin County EMA
Low-Priority
U.S. ACE’s Water Resources Development Act Section 22
Program
N/A
N/A
N/A
DATE OF
COMPLETION
PM-5
ES-2
ES-3
ES-11
SP-2
SP-3
SP-4
Implement the minimum building standards of the PA UCC
and/or consider adopting more stringent building standards
Coordinate with the U.S.G.S., local watershed organizations,
and/or the DCCD to increase the number of U.S.G.S. and
IFLOWS rain and stream gages in the County
Increase the number of NOAA Weather Alert radios in public
places across the County
Implement the recommendations of the Harrisburg Authority’s
ongoing combined sewer overflow impact study
Investigate the feasibility of increasing the Lawnton Branch of
Spring Creek’s underground flow capacity to minimize/eliminate
the Lawnton area’s flood hazard potential
Investigate the feasibility of constructing a levee/floodwall
system along Swatara Creek between East Main Street and the
Pennsylvania Turnpike to minimize Middletown Borough’s flood
hazard potential
Investigate the feasibility of constructing a levee/floodwall
system along the Susquehanna River to minimize Highspire
Borough’s backwater flood hazard potential
Municipal Staff/Officials N/A 2004
Dauphin County EMA with technical assistance
from the DCCD and/or the SRBC
Dauphin County EMA
Harrisburg City
Agency – FEMA/COE/PA DEP
Local – Municipal Staff/Officials
Agency – FEMA/COE/PA DEP
Local – Municipal Staff/Officials
Agency – FEMA/COE/PA DEP
Local – Municipal Staff/Officials
N/A
NWS’s Storm Ready Program
PennVEST Funding
PA DEP’s Growing Greener Program
U.S. ACE’s Continuing Authorities Program
PA DEP’s Flood Protection Program
U.S. ACE’s Continuing Authorities Program
PA DEP’s Flood Protection Program
U.S. ACE’s Continuing Authorities Program
PA DEP’s Flood Protection Program

TABLE 5-8
PRIORITIZED HAZARD MITIGATION ACTION PLAN
(CONTINUED)
PROJECT
ID
SP-5
SP-8
SP-9
SP-10
SP-11
NR-6
NR-7
PI-8
PROJECT DESCRIPTION RESPONSIBLE ENTITY POTENTIAL GRANT FUNDING SOURCES
Coordinate with the local municipality and/or the PA Department
of Transportation on the potential feasibility of replacing,
removing, or enlarging those bridge and culvert stream
crossings that were identified during the Act 167 Stormwater
Management Planning process as being unable to pass the 10-
year frequency flood flow
Coordinate with the PA DCNR Weiser Forest District and the
PA Game Commission on the potential construction of a
firebreak at the appropriate location on the south side of Peters
Mountain along Route 325 in Rush Township
Implement the suggested precautionary steps when using
structural abatement techniques to remedy surface-exposed
sinkhole features
Require expert technical assistance and establish mandatory
timeframes for structurally abating surface-exposed sinkhole
features that pose an identifiable threat to the general public
Coordinate with the PA Department of Transportation and the
DCCD to determine the feasibility of erecting protective fencing
in the known landslide hazard area along Route 147 north of
Millersburg in Upper Paxton Township
Develop and implement a wetland protection program
consisting of public education materials that highlight the
functions and values of wetlands and local ordinance provisions
that minimize/eliminate wetland disturbance
Ensure continued contractor compliance with approved Erosion
and Sedimentation Pollution Control Plans and continue to work
with local farmers to implement BMPs
Coordinate with FEMA, PEMA, DCED, NWS, DCCD and any
other appropriate entities on developing and implementing a
natural hazard awareness curriculum in local schools
Joint effort between the Dauphin County
Commissioners and the PA Department of
Transportation
Rush Township Supervisors with technical
assistance from the PA DCNR
Municipal Staff/Officials
Municipal Staff/Officials
Upper Paxton Township Supervisors with technical
assistance from the DCCD and PA Department of
Transportation
DCCD in potential consultation with the PA DCNR
and PA DEP
DCCD
Dauphin County Public Relations Office with
technical assistance from
FEMA/PEMA/DCED/DCCD and SRBC
PennDOT’s Accelerated Bridge Program
N/A
N/A
N/A
DATE OF
COMPLETION
N/A Summer 2008
PA Keystone Funds
PA DEP Growing Greener Funds
N/A

In addition to prioritizing the identified hazard mitigation measures, the Mitigation Steering
Committee also identified a responsible person/entity for implementing and administering
each of the identified mitigation measures. Depending on the scope of the project, this responsible
person/entity could range from a private property owner to a County department. Table
5-8 also suggests potential funding sources for implementing the respective projects. More
information on these potential funding sources is included in the next section.
Table 5-8 was adapted for this update plan to reflect items completed by municipalities
and new measures that were identified during the planning process. The table has been colorcoded
for ease of use. Measures which are shown in pink reflect those which have been
completed and require no further action. Those measures highlighted in blue have been
updated or replaced as a new measure. The measures identified in yellow are new measures
that have been written during the plan update process.
5.2.2 Potential Funding Sources
FEMA’s Pre-Disaster Mitigation and Hazard Mitigation Grant Programs (PDM and
HMGP) assist states and local communities in implementing long-term hazard mitigation
measures before and following a major disaster declaration, respectively. PDM and HMGP
monies can be used to fund projects that provide protection to either public or private property.
Some projects include structural hazard control, such as debris basins or floodwalls, and
retrofitting measures including floodproofing, acquisition and relocation of structures. FEMA can
fund up to 75 percent of the eligible costs of each project. The state or local match does not
have to be cash; in-kind services or materials may be used. Federal funding under the HMGP
is based on 15 percent of the federal funds spent on the Public and Individual Assistance
programs (minus administrative expenses) for each disaster. Eligible applicants must apply for
the PDM and HMGP through the Pennsylvania Hazard Mitigation Officer. More information is
available through the FEMA Web site (http://www.fema.gov/fima/mitgrant.shtm).
FEMA’s Flood Mitigation Assistance Program (FMAP) provides grants to states and
communities for planning assistance and mitigation projects that reduce the risk of flood damage
to structures covered by flood insurance. There are three types of grants: planning, project
and technical assistance. Technical assistance grants are given to state agencies that provide
assistance to communities, so communities apply for planning and project grants. FMAP
monies are available to eligible applicants when a Flood Mitigation Plan has been developed
and FEMA has approved it. FEMA may contribute up to 75 percent of the total eligible costs. At
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least 25 percent of the total eligible costs must be provided by a non-federal source. Of this 25
percent, no more than half can be provided as in-kind contributions from third parties. There are
limits on the frequency of grants and the amount of funding that can be allocated to a state or
community in any five-year period. PEMA serves as the administrator of the planning and
projects portions of the grant program. More information is available through the FEMA Web
site (http://www.fema.gov/fima/mitgrant.shtm).
FEMA’s Public Assistance Grant Program (PA) is one way federal assistance gets to
the state and local governments and to certain private nonprofit organizations. These grants
allow them to respond to disasters, to recover from their impact and to mitigate impact from
future disasters. While these grants are aimed at governments and organizations -- their final
goal is to help a community and all its citizens recover from devastating natural disasters.
The PA Program provides the basis for consistent training and credentialing of staff who
administer the program; more accessible and understandable guidance and policy for participating
in the grant program; improved customer service through a more efficient grant delivery
process, applicant-centered management, and better information exchange; and continuing
performance evaluations and program improvements. More information is available through the
FEMA Web site (http://www.fema.gov/rrr/pa/).
If the USACE determines that a project falls within the Continuing Authorities Program
(CAP), they initiate a short reconnaissance effort to determine federal interest in proceeding.
If there is interest, a feasibility study is performed, and the project continues through a
plans and specifications phase, and finally a construction phase. A local sponsor must identify
the flood-related problem and request USACE assistance. Small flood-control projects are also
eligible. The cost share for the CAP is 65 percent USACE and 35 percent local. The federal
project limit is $7,000,000. The USACE’s Baltimore District office would review the local sponsor’s
request for assistance and would request funds from the USACE’s annual appropriations.
More information is available through the USACE Web site (http://www.spk.usace.army.mil/
cespk-pd/cap.html).
The USACE’s Floodplain Management Services Program aims to support comprehensive
floodplain management planning to encourage and guide sponsors to prudent use of
the nation’s floodplains for the benefit of the national economy and welfare. Some examples of
the types of projects that would be funded include the following:
flood warning and flood emergency preparedness measures;
floodproofing measures;
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studies to improve methods and procedures for mitigating flood damages;
and
preparation of guides and brochures on flood-related topics.
A local sponsor must identify a problem and request USACE assistance under the Floodplain
Management Services Program. The USACE may provide up to 100 percent of the funding at
the request of the sponsor. The USACE’s Baltimore District office would review the local
sponsor’s request for assistance and determine if it fits within the program. More information is
available through the USACE Web site (http://www.nab.usace.army.mil/whatwedo/civwks/
fpms.htm).
The USACE’s Water Resources Development Act, Section 22 provides authority for
the USACE to assist states, local governments, and other non-federal entities in the preparation
of comprehensive plans for the development, utilization, and conservation of water and related
land resources. Congress funds the Planning Assistance to state programs annually. Federal
allotments for each state from the nationwide appropriation are limited to $500,000 annually but
typically are much less. Individual studies, of which there may be more than one per state per
year, generally cost $25,000 to $75,000. The program can encompass many types of studies
dealing with water resources issues. Types of studies conducted in recent years under the
program include the following:
Water Supply and Demand Studies;
Water Quality Studies;
Environmental Conservation/Restoration Studies;
Wetlands Evaluation Studies;
Dam Safety/Failure Studies;
Flood Damage Reduction Studies;
Flood Plain Management Studies;
Coastal Zone Management/Protection Studies; and
Harbor/Port Studies.
State or local governments that are interested in obtaining planning assistance under this
program can contact the appropriate USACE office for further details. Alternatively, interested
parties can contact the appropriate state coordinator to request assistance. In either case, the
USACE will coordinate all requests for assistance with the state coordinator to ensure that
studies are initiated on state prioritized needs. More information is available through the
USACE Web site (http://www.nab.usace.army.mil/whatwedo/civwks/pas.htm).
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The U.S. Department of Housing and Urban Development’s (HUD) Community
Development Block Grant - Disaster Recovery Initiative (DRI) program provides flexible
grants to help municipalities, counties, and states recover from Presidentially declared disasters,
especially in low-income areas. Since it can fund a broader range of recovery activities
than most other programs, the DRI helps communities and neighborhoods that otherwise might
not recover due to limited resources. When disasters occur, Congress may appropriate additional
funding for the Community Development Block Grant Program as DRI grants to rebuild
the affected areas and bring crucial seed money to start the recovery process. Grantees may
use DRI funds for recovery efforts involving housing, economic development, infrastructure and
prevention of further damage, if such use does not duplicate funding available from FEMA, the
Small Business Administration, and the USACE. Examples of these activities include the
following:
buying damaged properties in a floodplain and relocating them to safer
areas;
relocation payments for people and businesses displaced by the disaster;
debris removal;
rehabilitation of homes and buildings damaged by the disaster;
buying, constructing, or rehabilitating public facilities such as water and
sewer systems, streets, neighborhood centers, and government buildings;
code enforcement; and
planning and administration costs (limited to no more than 20 percent of
the grant).
HUD notifies eligible governments, which must then develop and submit an Action Plan for
Disaster Recovery before receiving DRI grants. The Action Plan must describe the needs,
strategies, and projected uses of the Disaster Recovery funds. More information is available
through the HUD Web site (http://www.hud.gov/offices/cpd/communitydevelopment/programs/
dri/ index.cfm).
The PA DCED Governor’s Center for Local Government Services sponsors the
Floodplain Land Use Assistance Program. This Floodplain Management Program focuses
on providing technical and financial assistance to local governments to help them adopt and
administer land use regulations and controls to reduce and avoid future flood damages. Munic-
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ipalities seeking assistance must be NFIP communities. Funds are available to assist in the
preparation, administration, and enforcement of floodplain management regulations.
Descriptions of state assistance programs were taken from the Catalog of Financial and
Technical Resources in the Growing Smarter Toolkit developed by the Governor’s Center for
Local Government Services. The toolkit is provided in the appendices.
The Land Use Planning and Technical Assistance Program (LUPTAP) is also
sponsored by PA DCED through the Governor’s Center for Local Government Services.
This program provides financial assistance for municipalities and counties of the Commonwealth
for developing and strengthening community planning and management. The program
encourages intergovernmental cooperation in planning, including cooperation with contiguous
municipalities, counties, and school districts. The LUPTAP program provides financial assistance
to fund activities such as preparing environmental protection or physical development
strategies or special studies that will support comprehensive planning and developing or updating
ordinances and other tools for the implementation of comprehensive community development
plans and policies or environmental protection or physical development strategies. PA
DCED generally funds 50 percent of the total cost of an approved application.
The PA DCNR is leading state efforts, under the Pennsylvania Greenways Initiative,
to implement the Greenways Action Plan. The PA Interagency Coordination Team, a team of
state agencies, will be pooling the agencies’ talents and resources to assist in the implementation
of the Plan. Each of Pennsylvania’s 67 counties is encouraged to consider greenways as
part of their land use strategy and to map their existing and proposed County greenway network
in a County Greenway and Open Space Conservation Plan. The outcome of the Plan is County
identification of priorities for conservation of open space and greenway corridors, which together
comprise a County “greenway network.” The “greenway network” includes linear greenway
corridors, related open space, and natural or manmade features or destinations like parks,
schools, or scenic natural areas that are linked by these corridors. An overall goal is the linkage
of the County Greenway and Open Space Conservation Plan to the County Comprehensive
Plan and other community planning and revitalization initiatives. When aggregated, County
greenway plans will lay the framework for Pennsylvania’s statewide greenway network as well
as provide a foundation for local greenways development. In some areas of the state where
other regional, multi-county planning efforts are already underway, counties can choose to work
together with neighboring counties to promote larger-scale regional planning and development
of a greenways network. Since greenways are often associated with stream corridors or other
important natural features, this program could easily supplement the initiatives contained herein
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egarding preservation of floodplains and other natural hazard-prone areas. Several funding
sources and programs are available to help communities meet the goals of the greenway
initiative.
Community Conservation Partnership Programs are sponsored by PA DCNR –
Bureau of Recreation and Conservation. Grants are provided for planning, acquisition, development,
and rehabilitation of park, recreation, conservation, greenways, and heritage areas and
facilities and, in some components, maintenance of trails. Some components of the program
offer funding for technical assistance, education, and training projects. Heritage Parks grants
can also fund promotion and marketing, special purpose studies and other heritage conservation,
tourism, and development projects. Generally, all grant components require a match,
usually 50 percent of cash or in-kind contributions. Eligible applicants are county and local
governments; municipal authorities; and nonprofit recreation, conservation, greenway, and
watershed groups.
The Growing Greener Grant Program is sponsored by the PA DEP Growing Greener
Grant Center. The purpose of this grant is to address water-quality-impaired watersheds in
Pennsylvania that are polluted by non-point sources of pollution such as abandoned mine
drainage, urban and agricultural runoff, atmospheric deposition, on-lot sewage systems, and
earthmoving. The grant addresses these and similar concerns through local, watershed-based
planning, restoration, and protection efforts.
PA DEP, Bureau of Watershed Management sponsors the state’s Stormwater Management
Program. This program provides grants to counties to develop stormwater management
plans for designated watersheds and to municipalities to implement the plans. The
Pennsylvania Stormwater Management Act (Act 167) requires that counties develop and adopt
stormwater management plans for the watersheds within their boundaries and also to update
those plans every five years. The municipalities located in the County-adopted watershed plan
areas are required to enact, implement, and administer stormwater control ordinances. The
grant assistance to counties and municipalities is limited to 75 percent of the costs for the
eligible expenses. PA DEP makes $1.2 million available for this program each fiscal year to
counties and municipalities.
PA DEP offers low-interest loans through the Pennsylvania Infrastructure Investment
Authority (PennVEST) for design, engineering, and construction of publicly and privately
owned drinking water distribution and treatment facilities, stormwater conveyance, and
wastewater treatment (WT) systems. These loans and grants are available to communities or
private firms needing clean drinking water distribution and treatment facilities and/or safe
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sewage and stormwater conveyance and treatment facilities. Communities may apply to
PennVEST for loans up to $11 million per project for one municipality, up to $20 million for more
than one municipality, up to $350,000 for design and engineering, and up to 100 percent of the
total project cost. In regards to flood planning, communities may apply for loans or grants
through PennVEST to help flood-proof sewage treatment or water treatment plant facilities.
Communities may also seek out PennVEST funds to upgrade stormwater control systems to
help minimize surface water flooding problems within developed areas. Through one form,
communities can apply for financial assistance through PennVEST or other PA DCED funding
sources.
5.3 MULTI-JURISDICTIONAL HAZARD MITIGATION STRATEGY
To fulfill FEMA requirements for multi-jurisdictional (i.e., multi-municipal) planning, each
respective municipality must have identifiable action items for potential implementation. As
evidenced by Table 5-8, over 70 hazard mitigation measures have been identified for potential
implementation within Dauphin County. While some of these recommended mitigation
measures are to be implemented by County personnel, many are to be implemented at the local
level by the appropriate municipal official(s). Additionally, given the myriad of regional differences
between various municipalities, certain hazard mitigation measures are only to be implemented
within select municipalities. As such, Table 5-9 has been developed to identify the
multi-jurisdictional approach to implementing the identified hazard mitigation measures. Table
5-9 enables Dauphin County’s various municipalities to easily identify those hazard mitigation
measures that are applicable to their particular jurisdiction. Table 5-9 was adapted for this
update plan to reflect items completed by municipalities and new measures that were identified
during the planning process using the original Table 5-9. The table has been color-coded for
ease of use. Measures which are shown in pink reflect those which have been completed and
require no further action. Those in orange have been completed but should be continued.
Those in green are no longer applicable to that particular municipality. Those highlighted in blue
have been updated or replaced as a new measure. The measures identified in yellow are new
measures that have been written during the plan update process. Development of this municipality-specific/multi-jurisdictional
hazard mitigation strategy fulfills FEMA’s requirements for
multi-jurisdictional plan implementation.
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TABLE 5-9
MULTI-JURISDICTIONAL HAZARD MITIGATION STRATEGY
Municipality
Implementation Measure
PM-1 PM-2 PM-3 PM-4 PM-5 PM-6 PM-7 PM-8 PM-9 PM-10 PM-11 PM-12 ES-1 ES-2 ES-3 ES-4 ES-5 ES-6 ES-7 ES-8 ES-9 ES-10 ES-11 ES-12 ES-13
Berrysburg Boro X X X X X X X X
Conewago Twp X X X X X X X X X X
Dauphin Boro X X X X X X X X X X
Derry Twp X X X X X X X X X X X
E. Hanover Twp X X X X X X X X X X X
Elizabethville Boro X X X X X X X X X X X
Gratz Boro X X X X X X X X X
Halifax Boro X X X X X X X X X X
Halifax Twp X X X X X X X X X X X
Harrisburg City X X X X X X X X X X X X
Highspire Boro X X X X X X X X X
Hummelstown Boro X X X X X X X X X X
Jackson Twp X X X X X X X X X X X
Jefferson Twp X X X X X X X X X X X
Londonderry Twp X X X X X X X X X X
Lower Paxton Twp X X X X X X X X X X X
Lower Swatara Twp X X X X X X X X X
Lykens Boro X X X X X X X X X X
Lykens Twp X X X X X X X X X X X
Middle Paxton Twp X X X X X X X X X X
Middletown Boro X X X X X X X X X
Mifflin Twp X X X X X X X X X X X
Millersburg Boro X X X X X X X X X X X
Paxtang Boro X X X X X X X X X X X
Penbrook Boro X X X X X X X X
Pillow Boro X X X X X X X X X X
Reed Twp X X X X X X X X X X X
Royalton Boro X X X X X X X X X
Rush Twp X X X X X X X X X X X
S. Hanover Twp X X X X X X X X X X
Steelton Boro X X X X X X X X X X
Susquehanna Twp X X X X X X X X X X X
Swatara Twp X X X X X X X X X X X
Upper Paxton Twp X X X X X X X X X X
Washington Twp X X X X X X X X X X
Wayne Twp X X X X X X X X X X X
W. Hanover Twp X X X X X X X X X X X
Wiconisco Twp X X X X X X X X X X X
Williams Twp X X X X X X X X X X X
Williamstown Boro X X X X X X X X X X X
Dauphin County X X X X X X X X X X X X X
Other (see below) 6 4,7 2,7 3,4 1,8
1-Property Owners
5-PA DCED 9-U.S. ACE X Measure has been completed, no further action is required
2-DCCD 6-PA DCNR 10-PA DEP X Measure has been completed, but should continue to be implemented
3-FEMA 7-SRBC 11-PennDOT Measure is no longer applicable
4-PEMA 8-Public Water Suppliers Measure has been replaced by a new measure
New measure

TABLE 5-9
MULTI-JURISDICTIONAL HAZARD MITIGATION STRATEGY
Municipality
ES-14 ES-15 ES-16 ES-17 ES-18 ES-19 ES-20 ES-21 ES-22 ES-23 ES-24 ES-25 PP-1 PP-2 PP-3 PP-4 PP-5 PP-6 PP-7 PP-8 SP-1 SP-2 SP-3 SP-4 SP-5
Berrysburg Boro X X X X X
Conewago Twp X X X X X X X X X X X X
Dauphin Boro X X X X X X X X X X X X X
Derry Twp X X X X X X X X X X X X X
E. Hanover Twp X X X X X X X X X X X X X
Elizabethville Boro X X X X X X X X X X X X X
Gratz Boro X X X X X X X X X X X X
Halifax Boro X X X X X X X X X X X X
Halifax Twp X X X X X X X X X X X X X
Harrisburg City X X X X X X X X X X X X X X
Highspire Boro X X X X X X X X X X X X X
Hummelstown Boro X X X X X X X X X X X X
Jackson Twp X X X X X X X X X X X X X X
Jefferson Twp X X X X X X X X X X X X X
Londonderry Twp X X X X X X X X X X X X X X
Lower Paxton Twp X X X X X X X X X X X X X
Lower Swatara Twp X X X X X X X X X X X X
Lykens Boro X X X X X X X X X X X X X X
Lykens Twp X X X X X X X X X X X X X
Middle Paxton Twp X X X X X X X X X X X X X
Middletown Boro X X X X X X X X X X X X X
Mifflin Twp X X X X X X X X X X X X X
Millersburg Boro X X X X X X X X X X X X X
Paxtang Boro X X X X X X X X X X X X
Penbrook Boro X X X X X
Implementation Measure
Pillow Boro X X X X X X X X X X X X
Reed Twp X X X X X X X X X X X X X
Royalton Boro X X X X X X X X X X X X
Rush Twp X X X X X X X X X X X X X
S. Hanover Twp X X X X X X X X X X X X
Steelton Boro X X X X X X X X X X X X
Susquehanna Twp X X X X X X X X X X X X X
Swatara Twp X X X X X X X X X X X X X X X
Upper Paxton Twp X X X X X X X X X X X X X
Washington Twp X X X X X X X X X X X X X
Wayne Twp X X X X X X X X
W. Hanover Twp X X X X X X X X X X X X X
Wiconisco Twp X X X X X X X X X X X X X X
Williams Twp X X X X X X X X X X X X X X
Williamstown Boro X X X X X X X X X X X X X
Dauphin County X X X X X X X X X X X X X X X
Other (see below) 1 2,7 1 7,9 1,6 1 3,4,5,7 3,9,10 3,9,10 3,9,10 3,9,10 11
1-Property Owners
5-PA DCED 9-U.S. ACE X Measure has been completed, no further action is required
2-DCCD 6-PA DCNR 10-PA DEP X Measure has been completed, but should continue to be implemented
3-FEMA 7-SRBC 11-PennDOT Measure is no longer applicable
4-PEMA 8-Public Water Suppliers Measure has been replaced by a new measure
New measure

TABLE 5-9
MULTI-JURISDICTIONAL HAZARD MITIGATION STRATEGY
Municipality
Implementation Measure
SP-6 SP-7 SP-8 SP-9 SP-10 SP-11 SP-12 NR-1 NR-2 NR-3 NR-4 NR-5 NR-6 NR-7 NR-8 PI-1 PI-2 PI-3 PI-4 PI-5 PI-6 PI-7 PI-8 PI-9 PI-10
Berrysburg Boro X X
Conewago Twp X X X X X X X X
Dauphin Boro X X X X X X X X X
Derry Twp X X X X X X X X X X X
E. Hanover Twp X X X X X X X X X X X
Elizabethville Boro X X X X X X X X X
Gratz Boro X X X X X X X X X
Halifax Boro X X X X X X X
Halifax Twp X X X X X X X X X
Harrisburg City X X X X X X X X
Highspire Boro X X X X X X
Hummelstown Boro X X X X X X X X X X
Jackson Twp X X X X X X X X X
Jefferson Twp X X X X X X X X X
Londonderry Twp X X X X X X X X X
Lower Paxton Twp X X X X X X X X X X X X
Lower Swatara Twp X X X X X X X X X X X
Lykens Boro X X X X X X X X X
Lykens Twp X X X X X X X X X
Middle Paxton Twp X X X X X X X X X
Middletown Boro X X X X X X X X
Mifflin Twp X X X X X X X X X
Millersburg Boro X X X X X X X X X
Paxtang Boro X X X X X X X
Penbrook Boro X X X
Pillow Boro X X X X X X X X X
Reed Twp X X X X X X X X X
Royalton Boro X X X X X X X X
Rush Twp X X X X X X X X X X
S. Hanover Twp X X X X X X X X X X X
Steelton Boro X X X X X X X X
Susquehanna Twp X X X X X X X X X X X X
Swatara Twp X X X X X X X X X X X
Upper Paxton Twp X X X X X X X X X X
Washington Twp X X X X X X X X X
Wayne Twp X X X X X X X X X
W. Hanover Twp X X X X X X X X X X X
Wiconisco Twp X X X X X X X X X
Williams Twp X X X X X X X X X
Williamstown Boro X X X X X X X X X
Dauphin County X X X X X X X X X X X X X X X X
Other (see below) 2,3,9,10 6 2,11 6 6 2,6,10 1,2 2,7,10 2,3,5,7 2,3,4,5 2
1-Property Owners
5-PA DCED 9-U.S. ACE X Measure has been completed, no further action is required
2-DCCD 6-PA DCNR 10-PA DEP X Measure has been completed, but should continue to be implemented
3-FEMA 7-SRBC 11-PennDOT Measure is no longer applicable
4-PEMA 8-Public Water Suppliers Measure has been replaced by a new measure
New measure

6.0 PLAN MAINTENANCE PROCEDURES

6.0 PLAN MAINTENANCE PROCEDURES
6.1 MONITORING, EVALUATING, AND UPDATING THE PLAN
Dauphin County has established a procedure for monitoring, evaluating, and updating
this hazard mitigation plan. Monitoring of this hazard mitigation plan shall continue as an
ongoing process conducted by DEMA and coordinated with the representative members of the
Mitigation Steering Committee on an annual basis via a report memorandum to be submitted by
December 31 of each year. DEMA will continue to track overall plan progress not only at the
County-level but also at the municipal level via coordination with local emergency management
coordinators at their monthly training sessions. The County will continue to use Table 5-8 to
record the date of completion of the various hazard mitigation recommendations and Table 5-9
to track progress at the individual municipal-level. The end-of-year report memorandum will
summarize that year’s progress towards meeting the identified hazard mitigation planning goals.
In regard to updating the hazard mitigation plan, the Mitigation Steering Committee will
continue to reconvene on a five-year basis to review the County’s annual monitoring activities,
evaluate the current effectiveness of the hazard mitigation plan, and make any needed updates/changes
to the hazard mitigation plan. The five-year review will evaluate the hazard
mitigation plan in regard to its current accuracy, relevance, and applicability. In particular, the
Mitigation Steering Committee will review the hazard mitigation plan in light of the following.
The ability of the identified hazard mitigation planning goals to address
current and anticipated future conditions.
Any known or perceived changes in the County’s vulnerability to the identified
hazards.
The current capabilities (i.e., institutional, legal, fiscal, political, and technical)
of the County and its constituent municipalities.
The successes, failures, and/or lessons learned from implementing the
identified hazard mitigation recommendations during the preceding fiveyear
period.
The need to address additional hazards in the plan and/or the need for
other modifications to the plan
Advances in the County’s GIS structure database that would allow for
more detailed analysis of asset vulnerability and loss estimation.
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If the Mitigation Steering Committee determines that updates and/or changes are needed to the
hazard mitigation plan, assignments will be made to the representative members and the
Committee will meet as deemed necessary until all updates and/or changes have been completed
and incorporated into the hazard mitigation plan. It will be the responsibility of DEMA to
oversee the plan review/update process and to coordinate all plan revisions with the appropriate
municipalities.
One update already identified as necessary by the Mitigation Steering Committee is the
extension of the planning effort to create an all-hazard plan for Dauphin County. Specifically,
man-made or non-natural hazards are to be added to this plan following the same approach and
format contained herein. The recommended scope of work for this proposed effort is included in
the appendices.
Additional updates to the hazard mitigation plan will be completed upon development of
the County’s GIS program. In particular, as the County develops/refines its GIS structure
database (to include building type, use, ownership, address, and assessment) more detailed
analysis of asset vulnerability and loss estimation can be conducted. Having a more detailed
GIS structure database (as described above) would enable an exact count of the type and value
of buildings in known hazard areas to be generated. This level of data would greatly enhance
the asset vulnerability and loss estimation sections of the plan (see Chapter 2) and should be
included as a future update to the plan.
6.2 IMPLEMENTATION THROUGH EXISTING PROGRAMS
Implementation of the new and ongoing hazard mitigation recommendations outlined in
this plan will continue upon plan adoption. Analysis of PM-1 indicates that the municipalities are
encouraged to develop a new or amend their existing Comprehensive Plan to include hazard
related provisions. As such, it is anticipated that those municipalities with an existing Comprehensive
Plan will be re-adopting this updated hazard mitigation plan as an amendment to their
Comprehensive Plan, thus fulfilling PM-1. By so doing, those municipalities will be continuing
their local hazard mitigation program simply by re-adopting this updated hazard mitigation plan.
Similarly, those municipalities can then proceed to revise other existing local planning documents
(i.e., capital improvement plan, zoning ordinance, subdivision and land development
ordinance, building code, floodplain ordinance, etc.) as appropriate to implement any new or
ongoing hazard mitigation recommendations that apply to their jurisdiction. Ultimately, it will be
left to the discretion of the individual municipalities to revise their existing policies, plans, and
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programs to be consistent with and to help implement the updated hazard mitigation planning
recommendations.
For those municipalities that do not have an existing Comprehensive Plan, the critical
first step will be to re-adopt this updated hazard mitigation plan as a stand-alone document.
Once this occurs, those municipalities will then be free to implement the new and ongoing
hazard mitigation recommendations that are applicable to their respective jurisdiction. It is
understood, however, that in certain instances, select municipalities may not have any existing
programs through which to implement the hazard mitigation recommendations. This concept
was clearly defined in the Capability Assessment (see Chapter 4) and is not to be interpreted as
an inability to implement the hazard mitigation recommendations. Rather, implementation of the
hazard mitigation recommendations in these select municipalities may be accomplished through
cooperative arrangements, more coordinated efforts, and/or resource efficiency.
6.3 CONTINUED PUBLIC INVOLVEMENT
Dauphin County is committed to involving the public in the continual reshaping and
updating of this hazard mitigation plan. DEMA is responsible for monitoring the plan and for the
five-year review/update of the plan. In this capacity, it will also be the responsibility of DEMA to
coordinate with the Dauphin County Public Relations Office to implement long-term public
participation activities.
In accordance with PI-9, copies of this updated hazard mitigation plan will be catalogued
and kept on file at public libraries and municipal buildings throughout the County. In addition,
the updated plan will be posted on the County’s Web site. This site will also contain contact
information to which people can direct their comments or concerns. Finally, similar to that which
was completed for this hazard plan update, a public meeting will be held after each five-year
review/update of the plan. This meeting will provide the public an opportunity to express
concerns, opinions, or ideas about the plan. The Dauphin County Public Relations Office, in
coordination with DEMA, will be responsible for organizing and advertising this public meeting.
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