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Integrating Disaster Planning into Historic Resource Survey

Successful integration of disaster planning with historic preservation requires a more expansive approach to historic resource survey than is typically used. A field survey provides a unique opportunity to collect information on the types of hazards and the extent of threat from those hazards to resources in addition to architectural details, alterations, and other information relevant to historic significance and integrity.

With this in mind, the Pennsylvania State Historic Preservation Office developed specialized Historic Resource Natural Hazard Vulnerability Forms to capture hazard vulnerability data including flood zone and elevation information. A detail of an example form is excerpted below for reference:

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Pilot Counties Phase 1 

Bedford, Cameron, and Monroe Survey

Flooding is the leading natural hazard threatening the built environment in Pennsylvania communities, as identified in the Commonwealth of Pennsylvania State Standard All-Hazard Mitigation Plan (PEMA, 2013) and in the individual county-level (multijurisdictional) hazard mitigation plans for Bedford, Cameron, and Monroe counties.

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Recognizing the impact of flooding upon Pennsylvania communities, the PASHPO commissioned a countywide survey of historic resources in the 100-year (1% annual-chance) and 500-year (0.2% annual-chance) flood hazard areas in each of the pilot project counties. As part of this survey to document previously unidentified historic resources (buildings, structures, districts, sites, and objects), the survey teams revisited properties already recorded in the counties' and the Commonwealth's historic resource inventories, including properties already listed in the National Register of Historic Places, to update records and collect information on their precise location within floodplains and the vertical elevation of buildings' first floor level and openings (doors and windows, etc.) where water may enter during a flood event.

This information, which largely does not exist to date for Pre-FIRM buildings (those constructed prior to 1975, or before most communities' first FEMA Flood Insurance Rate Maps (FIRMs) were produced in the United States), will enable hazard mitigation planners to better understand, and in some cases predict, how and which historic buildings may become damaged during a flood. The information will also enable hazard planners to estimate historic building replacement costs and develop effective risk reduction strategies to better protect these community assets and preserve them for future generations, as well as potentially reduce flood insurance premiums for the owners of historic buildings.

In many cases, the field survey enabled by this project has been the first comprehensive countywide survey of historic resources that the pilot counties have seen in as many as 30 years, and will provide a much-needed update to the counties' and the PASHPO's records. Additionally, historic resources newly identified as part of this survey effort that may be determined eligible for listing in the National Register of Historic Places, may in turn become eligible for a host of state and federal grant opportunities and tax incentives including the state and federal Historic Preservation Tax Credits.

Final reports documenting the methodology and findings from the Phase 1 projects in Monroe, Bedford, and Monroe counties are available for download below.

The integration of historic property considerations in the hazard mitigation plans of Bedford, Cameron, and Monroe counties is anticipated for completion in 2018.

Philadelphia Survey

The Philadelphia pilot project of the Disaster Planning for Historic Properties Initiative represents the first time that a major U.S. city's historic resources have been assessed in terms of their level of risk to natural hazards, and the first time that the information resulting from such analysis will be incorporated into a major U.S. city's FEMA-approved hazard mitigation plan.

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The Philadelphia pilot project has focused specifically on the impacts of flooding (the leading naturally occurring hazard affecting Pennsylvania communities, including the "City of Brotherly Love") and has prioritized historic buildings and structures (those currently listed in the National Register of Historic Places and/or the Philadelphia Register of Historic Places, either individually or contributing to a listed district) that may be vulnerable to a variety of flooding scenarios including inundation from 100-year and 500-year storms, tropical storms/hurricanes, and inundation resulting from up to 6 feet of sea-level-rise.  

The PA SHPO identified over 500 historic buildings or structures vulnerable to one or more flooding scenarios in Philadelphia. Many of these resources are not only nationally important landmarks; they are integral to the city's sense-of-place and cultural identity. Many of these resources are significant for their contributions to industrial and military history, and reflective of Philadelphia's role as the "Birthplace of the United States" and the "Workshop of the World". The following are examples of some of the most widely recognized flood-prone resources in the city:

  • Boat House Row (National Historic Landmark)
  • Fort Mifflin (National Historic Landmark)
  • Fairmount Water Works (National Historic Landmark)
  • Philadelphia Naval Shipyard (National Historic District)
  • Schuylkill Historic District (National Historic District)
  • Manayunk Main Street Historic District (National Historic District)
  • Rittenhouse-Fitler Historic District (Local Historic District)

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The PA SHPO contracted with AECOM Technical Services to resurvey each of the 500-plus flood-prone historic resources to update documentation and collect new information on character-defining features that may be susceptible to flood damage. The U.S. Army Corps of Engineers maximized the impact of the project by deploying crews to record building elevation information (including first floor elevation and the elevation of the lowest and highest adjacent grade) for designated historic buildings located in flood prone areas. This information, captured on new Historic Resource Natural Hazard Vulnerability Survey Forms, will help hazard mitigation planners to better understand how and when Philadelphia's historic buildings may become damaged during various flood scenarios, and to develop sensitive risk reduction measures accordingly.

For more details on the methodology and findings of AECOM Technical Services, Inc.'s Phase 1 activities in Philadelphia, please see the City of Philadelphia Disaster Planning for Historic Properties Phase 1 Historic Building Flood Vulnerability Assessment Data Recordation Final Report.

Parallel to PA SHPO's Phase 2, the US Army Corps of Engineers National Nonstructural Flood Proofing Committee (NNFPC) began developing sensitive mitigation measures for specific historic resources in Philadelphia, some of which represent common building types such as the Workingman's House, that will have a minimal visual impact on the integrity of the city's historic buildings.

The final product of NNFPC's efforts, the Philadelphia Historic Resource Flood Hazard Vulnerability Study, was completed in 2018 and provides recommended hazard mitigation actions for 25 historic resources in the city. The report also includes diagrammatic building sections showing how projected flooding would affect the selected properties. See an example below representing 6 Boathouse Row:

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Pilot County Phase 2 Reports

Because Philadelphia, Cameron County, Bedford County, and Monroe County were intended to serve as pilots for future survey efforts, PA SHPO contracted with Vision Planning & Consulting to produce Phase 2 reports using each county's Phase 1 report as a basis. These reports prioritized the development of sensitive hazard mitigation alternatives to protect and/or minimize damage to the counties' historic assets in advance of future hazard events (including, but not limited to, floods) and the integration of those strategies into the counties' FEMA-approved hazard mitigation plans (HMPs), along with detailed inventories of vulnerable historic properties and vulnerability assessments.

Phase 2 Property Sheets

To quickly illustrate the hazards and potential hazard mitigation measures that could impact a property, a one-page (front and back) 'property sheet' for each of the representative properties in Bedford, Cameron, and Monroe Counties, and for each building typology in Philadelphia was created.

These property sheets address a diverse range of building forms, styles, conditions, and associated hazard mitigation actions.  While these sheets were not created for every individual property at risk in the pilot counties, this diversity is intended to be representative enough to help anyone determine appropriate preservation-based hazard mitigation actions for their own at-risk properties.

Each property sheet includes:

  • elevation and hazard-related information from the Phase I survey forms
  • results of the GIS analysis including estimated flood depth during a 100-year flood event
  • architectural considerations and at-risk features
  • photos that illustrate the property
  • a list of recommended sensitive hazard mitigation actions based on the building's style and historic features

Where data was available, a visual rendering of a 100-year flood event was produced for the property sheet to show just how high floodwaters would reach. See below for an example showing the Juniata Woolen Mill in Bedford County:

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