Section 4: Hazard Identification and Risk Assessments February 2016 Section 4: Hazard Identification and Risk Assessments
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Section 4: Hazard Identification and Risk Assessments February 2016 Section 4: Hazard Identification and Risk Assessments 2016 Plan Update changes: This section combines Sections 6 and 7 into one section. Where possible, the content has been updated to reflect the best data available. 4.1 Introduction During the 2016 Plan update many parts of the original County HMP were preserved. Where applicable, portions of the historical hazard data have been retained. This section addresses the specific requirements of the Interim Final Rule (IFR) and FEMA checklist requirements (Local Mitigation Plan Review Tool, October, 2011) with regard to hazards in the planning area. As required by federal planning guidelines, one of the key elements of the 2016 HMP update was to describe the events and effects of natural hazards on the County since the original version of the Plan was developed and adopted in 2010. In addition detailed risk assessments were completed for all hazards ranked high (hazards of concern) or medium by the 2016 Hazard Mitigation Planning Steering Committee (HMPSC). The term “planning area” is used frequently in this section. This term refers to the jurisdictional limits of Middlesex County. The Risk Assessment section addresses the potential future damages from hazards on Middlesex County and its citizens. 4.1.1 Summary Description of the County’s Vulnerability to Hazards The DMA 2000 legislation and related FEMA planning guidance require mitigation plans to include discussion of community vulnerability to natural hazards. Vulnerability is generally defined as the damage (including direct damages and loss of function) that would occur when various levels of hazards impact a structure, operation or population. For example vulnerability can be expressed as the percent damage to a building when it is flooded, or the number of days that a government office will be shut down after a wind storm, etc., assuming there is sufficient detailed data available to support the calculations. Because this Plan update includes many jurisdictions and data is often not detailed, it is not practical to complete vulnerability assessments on the many individual assets, operations and populations in individual jurisdictions. However, it is appropriate for participating municipalities to embark on a program of addressing these data deficiencies over the next five years in anticipation of the next Plan update. As illustrated in the present section of the HMP update, Middlesex County is subject to numerous natural and manmade hazards, although in some cases the hazards have rarely impacted the area, or their effects have been relatively minor. As is the case with many parts of the mid-Atlantic, although relatively localized, flooding is the most frequent and most damaging natural hazard in central New Jersey and Middlesex County, However, it is important to recognize that several other hazards present significant risks (i.e. potential for future losses) to the County, even though they have occurred Middlesex County, New Jersey: 2016 Hazard Mitigation Plan Update 4-1 Section 4: Hazard Identification and Risk Assessments February 2016 infrequently in the past, or have not caused much damage. In particular, earthquakes (although improbable) present risks to various communities within the County, because there are many relatively old structures that may be prone to failure if shaken by an earthquake. In order to accurately characterize vulnerabilities (and hence risks) at a local level, it will be necessary to study assets on a site-specific basis. There is also some vulnerability to wind in the County, mainly from hurricanes and tropical storms. While severe hurricanes are rare events in this area of the country, tropical storms and nor’easters are fairly common, and many structures in the communities are vulnerable to high winds. Most of the other hazards are either localized or improbable, and therefore, while various elements in the communities may be vulnerable to such hazards, the likelihood of them occurring in any specific location is very small. 4.2 Identification, History and Prioritization of Hazards In accordance with IFR requirements, and as part of its efforts to support and encourage hazard mitigation initiatives, the 2016 HMPSC prepared this general assessment of the hazards that have potential to impact the County. The following subsections provide an overview of past hazard events in the County and descriptions of the potential for future losses. Under the subsection Methodology for Prioritizing Hazards beginning on Page 4-3 the hazards are ranked (high, medium, or low) based on the overall impact to the County. In addition, jurisdiction specific hazards have been identified and profiled for each municipality in Appendices 1-20. These hazards were identified by municipality point of contacts after a series of meetings and workshops held with each of the 25 jurisdictions. See Section 4 of the Plan update and the municipal appendices for additional details about the process for selecting these hazards and the hazard identified for each jurisdiction. 4.2.1 Overview of the Type and Hazards That Can Affect Middlesex County In the initial identification process, the HMPSC catalogued potential hazards to identify those with the most chance to significantly affect the County. The hazards include those that have occurred in the past and may occur in the future. A variety of sources were used in the investigation. These included national, regional, and local sources such as emergency operations plans, the State Hazard Mitigation Plan, websites, published documents, databases, and maps, as well as discussion with the HMPSC. In its early meetings related to this HMP update, the HMPSC reviewed the hazards included in the 2010 Hazard Mitigation Plan and identified a total of 15 hazards that have potential to affect the County. The 15 hazards include the addition of three new hazards that were not profiled in the 2010 Plan including Levee Failure, Power Loss and Nor’easters. Of the original 18 hazards profiled in the 2010 Plan only one is not included in the 2016 Plan update (Lightning). The 2016 HMPSC felt this hazard was covered under Severe Weather. The 15 hazards profiled as part of the 2016 Plan update are listed below. 1. Coastal Erosion 2. Dam/Levee Failure* 3. Drought 4. Earthquakes Middlesex County, New Jersey: 2016 Hazard Mitigation Plan Update 4-2 Section 4: Hazard Identification and Risk Assessments February 2016 5. Extremely High Temperatures 6. Extremely Low Temperatures 7. Flood (Riverine, Coastal, Storm Surge, local, and Sea Level Rise) 8. Geologic Hazards (Landslides, Subsidence, and Sinkholes) 9. Hazardous Materials (Fixed Sites, Rails, and Other Transportation) 10. Hurricanes and Tropical Storms 11. Nor’easters* 12. Power Outages* 13. Severe Weather (High Winds, Tornadoes, and Hail) 14. Wildfire 15. Winter Storm (Snow, Blizzards, and Ice Storms) * New for 2016 Plan Update. Note that the Levee Failure portion of the Dam/Levee Failure hazard is new for the 2016 update. 4.2.2 Methodology for Prioritizing Hazards The 2016 HMPSC reviewed these hazards (including the hazard profiles and risk assessments) and prioritized them as high, medium, or low based on the overall impact to the County. They considered factors such as how often the hazard occurred, degree of property and infrastructure damage, number of people impacted, and time of recovery. The hazard prioritization table is provided below and describes the rationale for the hazard ranking. It also shows sources of information that were consulted for the determination. Although all 15 of the hazards are profiled in this section, the prioritization was used as a basis to focus vulnerability and risk assessment activities on those hazards with the most potential to negatively affect the County. Those hazards prioritized as high or medium by the HMPSC include more extensive discussions about vulnerability and risk than those with lower rankings. There is more information about location-specific hazards and vulnerabilities in the jurisdictional appendices. The 2016 HMPSC identified 6 of the 15 hazards profiled as multi-jurisdictional or county-wide hazards of high concern (ranked high). As the regulations indicate, all of these identified hazards must be profiled, their vulnerability assessed, and mitigation actions developed for them. The remaining hazards were ranked medium or low. The high, medium and low rankings for the 15 hazards are shown below. Middlesex County, New Jersey: 2016 Hazard Mitigation Plan Update 4-3 Section 4: Hazard Identification and Risk Assessments February 2016 Table 4-1 Middlesex County (County-wide) Hazard Ranking Table (Source: HMPSC) Level of Hazard Rationale Sources Concern FEMA Flood Insurance Studies, FEMA Flood Insurance Rate Maps, FEMA Public Assistance Flood (Riverine, records, FEMA National Flood Insurance Coastal, Storm Widespread impacts, history of occurrences Program claims data, US Army Corps of High Surge, Local, and in the county, significant annual damages Engineers (USACE), and National Sea Level Rise) Oceanographic and Atmospheric Administration (NOAA), studies and records, HAZUS. Hurricanes: Relatively low historic NOAA and National Climatic Data Center probability; potential for widespread (NCDC) records, New Jersey Department of Hurricanes and impacts. High Community Affairs - Division of Codes and Tropical Storms Tropical Storms: Low to moderate Standards, New Jersey State Climatologist probability; potential for widespread (Rutgers)