SECTION 4: RISK ASSESSMENT
4.5.14 HAZARDOUS MATERIALS INCIDENT HAZARD BACKGROUND
A hazardous substance is any substance that may cause harm to persons, property, or the environment when released to soil, water, or air. Chemicals are manufactured and used in increasing types and quantities. Each year over 1,000 new synthetic chemicals are introduced and as many as 500,000 products pose physical or health hazards and can be defined as “hazardous chemicals”. Hazardous substances are categorized as toxic, corrosive, flammable, irritant, or explosive. Hazardous material incidents generally affect a localized area.
FIXED HAZARDOUS MATERIALS INCIDENT
A fixed hazardous materials incident is the accidental release of chemical substances or mixtures during production or handling at a fixed facility.
TRANSPORTATION HAZARDOUS MATERIALS INCIDENT A transportation hazardous materials incident is the accidental release of chemical substances or mixtures during transport. In Wake County, these incidents can occur during highway or air transport. Highway accidents involving hazardous materials pose a great potential for public exposures, particularly for nearby populations and motorists. If airplanes carrying hazardous cargo crash, or otherwise leak contaminated cargo, populations and the environment in the impacted area can become exposed. PIPELINE INCIDENT A pipeline transportation incident occurs when a break in a pipeline creates the potential for an explosion or leak of a dangerous substance (oil, gas, etc.) possibly requiring evacuation. An underground pipeline incident can be caused by environmental disruption, accidental damage, or sabotage. Incidents can range from a small, slow leak to a large rupture where an explosion is possible. Inspection and maintenance of the pipeline system along with marked gas line locations and an early warning and response procedure can lessen the risk to those near the pipelines.
Warning Time Score: 4 – Less than six hours
Duration Score: 2 – Less than 24 hours LOCATION
The Toxics Release Inventory (TRI) Program run by the U.S. Environmental Protection Agency (EPA) maintains a database of industrial facilities across the country and the type and quantity of toxic chemicals they release. The EPA reports 35 TRI sites in Wake County. Wake County Emergency Management also tracks Tier II facility data, which covers facilities that are required to report to the EPA under the Emergency Planning and Community Right-to-Know Act (EPCRA) because they have hazardous materials present in quantities equal to or greater than 500 lbs, 55 gallons, or the Threshold Planning Quantity. Wake County has approximately one fourth of the Tier II reporting facilities in the state of North Carolina, with over 2,300 facilities in 2023. TRI and Tier II sites are shown in Figure 4.33. The U.S. Department of Transportation (USDOT) Pipeline and Hazardous Materials Safety Administration (PHMSA) maintains an inventory of all gas transmission and hazardous liquid pipelines, liquid natural gas plants, and hazardous liquid breakout tanks. The location of pipelines and pipeline infrastructure in Wake County are shown in Figure 4.34, per the National Pipeline Mapping System.
Wake County, NC Multi-Jurisdictional Hazard Mitigation Plan
WSP June 2024 Page 248
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