BENTON COUNTY 2016 MULTI-JURISDICTIONAL HAZARD MITIGATION PLAN SECTION 5 SECTION 5 RISK ASSESSMENT ASSESSING VULNERABILITY Overview An overview of the planning area’s vulnerability is a summary of the hazard’s impact on the community and its vulnerable structures. To determine what populations or properties could be lost to a particular hazard event, the hazard locations discussed in the hazard profiles section are classified below. Some hazards do have defined risk areas, i.e. they will only occur in certain places, while other hazards could affect the entire town, or any smaller portion of the town. Hazards with well-defined risk areas with risk of structural damage: Flash Flood, River Flood The majority of these areas have been identified as best as currently possible within the hazard profiles. People living, working, or otherwise being present inside these risk areas, as well as structures inside these risk areas, are most vulnerable to the effects of these hazards. While these hazards may have an extremely detrimental impact on lives and property in their path, the typical occurrences of these hazards will not impact other people or property within the jurisdiction, except when a critical facility is impacted. An example of this would be flooding of the sewer plants, which could be caused by flash flooding, riverine flooding or a dam failure, which would in-turn impact larger areas of town outside of the defined hazard area. Hazards with well-defined risk areas and little to no risk of structural damage: None Hazards with specific areas of elevated risk with risk of structural damage: Wildfire, Transportation Incident, Hazardous Materials Incident Hazards with specific areas of elevated risk are those that are more likely to occur in a certain identified location. However they are not guaranteed to be limited to that location. Wildfires normally only impact areas with enough vegetative, fuel, and slopes necessary to sustain a fire. Other factors may impact the spread of a wildfire, such as materials stored in specific areas that may ignite and spread a fire over a greater area than might have been predicted by vegetation and terrain alone. Transportation events as well as hazardous materials events can almost always be expected to occur in specific areas: transportation events will likely originate on or near roadways, railroads or other transportation infrastructure; many hazardous materials sights are well known to first responders and have federal and state reporting requirements. However, it is difficult to predict the magnitude of any specific event because these types of events are accidental, and thus the circumstances surrounding these events will impact the extent of damage or injuries that occur. 326 BENTON COUNTY 2016 MULTI-JURISDICTIONAL HAZARD MITIGATION PLAN SECTION 5 Hazards without defined areas of elevated risk with risk of structural damage: Thunderstorms/Lightning/Hail, Severe Winter Storm, Hailstorm, Tornado, Windstorm, Structural Fire, Terrorism, Transportation Incident These hazards have no defined area in which they are known to occur, and could occur in either limited sections of the jurisdiction or over the entire jurisdiction at once. These hazards are also able to directly cause substantial structural losses, and potentially loss of life. Hazards without defined areas of elevated risk, without high risk of structural damage: Infrastructure failure, Extreme Heat, Drought, Animal-Plant-Crop Disease, Human Disease These types of hazards are those that could occur anywhere within the jurisdiction, or could occur throughout the entire jurisdiction and for which it is not possible to determine beforehand where the hazard is most likely to occur. Additionally, any of these hazards could occur without causing damage to the structures in the jurisdiction. While this does not indicate that any of these events could not be combined with other hazards or circumstances to create property damage, rather they were determined to be least likely to directly cause structural damage. However, these hazards will still create losses, which are likely to be economic, either due to a disruption in the provision of an essential service or to a loss of some type of product such as crop failure. Table 136: Overall Summary of Vulnerability by Jurisdiction Key: L = Low to no risk; little damage potential M = Medium risk; moderate damage potential or infrequent occurrence H = High risk; significant risk or major damage potential or frequent hazard occurrence Hazard Identified Atkins Vinton Urbana Luzerne Norway Walford Newhall Garrison Keystone Shellsburg Van Horne Van Blairstown Mt. Auburn Belle Plaine Plaine Belle Benton County County Benton Unincorporated ANIMAL/CROP/PLANT DISEASE M L L L M L L L L M L L L L L DROUGHT M M L L M L H M L L L L L L L EXTREME HEAT M L M M M L H M L M M M M M M FLASH FLOOD L L H L L L L L L H H L L H M 327 BENTON COUNTY 2016 MULTI-JURISDICTIONAL HAZARD MITIGATION PLAN SECTION 5 Hazard Identified Atkins Vinton Urbana Luzerne Norway Walford Newhall Garrison Keystone Shellsburg Van Horne Van Blairstown Mt. Auburn Belle Plaine Plaine Belle Benton County County Benton Unincorporated GRASS OR WILDLAND FIRE M L L M L M L M L M M M L L L HAZARDOUS MATERIALS L H H H L H H L M H H H M H H HUMAN DISEASE L L M M L L L L L L L L M M M INFRASTRUCTURE FAILURE M M M L M L L L L M M M L H M RIVER FLOODING L N/ L N/ N/ N/ N/ N/ N/ N/ N/ N/ N/ H N/ A A A A A A A A A A A A SEVERE WINTER STORM H H M H H M H H H M M M M H M STRUCTURAL FIRE L M M M L M H H M M M M M H M TERRORISM L M M L L M L L L M M M M H M THUNDERSTORM/LIGHTN M M M M H H M M M M M M M M M ING/HAIL TRANSPORTATION INCIDENT L H H L L M L M L M M H M H H TORNADO/WINDSTORM H H M H H M H H M H H H H H M REPETITIVE LOSS PROPERTIES Repetitive loss properties are those for which two or more looses of at least $1,000 each have been paid under the National Flood Insurance Program (NFIP) within any 10-year period since 1978. Local governments may obtain information on repetitive loss properties within their jurisdiction by contacting their State NFIP Coordinator. Use of the flood insurance claim and disaster assistance information is subject to The Privacy Act of 1974, as amended, which prohibits public release of the names of policy holders or recipients of financial assistance and the amount of the claim payment or assistance. For the purposes of preparing this plan, the consultant requested information from the Iowa Department of Homeland Security and Emergency Management about repetitive loss structures in Benton County. Officials of the Homeland Security and Emergency Management Division of Iowa (HSEMD) report that there are two repetitive loss structures in Benton County. Both are residential. One property is located in Vinton and one property is located in Mt. Auburn. This is the only information that could be obtained. 328 BENTON COUNTY 2016 MULTI-JURISDICTIONAL HAZARD MITIGATION PLAN SECTION 5 IDENTIFYING STRUCTURES Hazard mitigation plans should describe vulnerability in terms of the types and numbers of existing and future buildings, infrastructure and critical facilities located in the identified hazard areas. Thus, the next step in the planning process was to determine who and what is at risk in the event that any of the selected hazards do occur. To determine this, the consultant provided an overview of the potential property losses by assessment classification to provide a sense of what property could be lost in addition to the populations detailed in the community profile. Building Stock This data represents the 2014 assessed values and 2013 population estimate based on where people live rather than where they work (or attend school). The source for this data is the Benton County Assessor’s office and the 2013 population estimate from the US Census Bureau. This was the most recent and up-to-date information available at the time this section was developed. Values for tax- exempt structures are not available. Additional, more specific building type classifications are also not available. When interpreting the data above to provide loss estimates for the jurisdiction in a worst- case scenario event, it is also useful to keep in mind that the assessed value of the property is presented, which may not directly correlate to the fair market or replacement value of that property. A common method used in Iowa to adjust from assessed value to fair market value is to increase the assessed value by 110%, however every property is unique and this may not be accurate in all cases. As previously discussed in the vulnerability overview section, only certain hazards have well defined risk areas, and only some of those hazards pose a risk of structural losses. Thus, the hazard of riverine flooding and flash flooding, are the only hazards examined in this document where it is possible to identify the structures that are at risk should one of these hazards occur. The hazards of expansive soils and landslide are not examined because the mitigation planning committee decided not to include them in the plan based on information provided by the USDA NRCS which showed low or no hazard for the county for these two hazards.