Orange County Water & Wastewater Multi-Jurisdictional Hazard Mitigation Plan 2024
Exhibit O-3. IRWD Hazard Identification (cont.)
Geographic Affected Area ▪ 1 = Isolated, less than 10% of planning area ▪ 2 = Small, 10-30% of planning area ▪ 3 = Medium, 30-60% of planning area ▪ 4 = Large, 60-100% of planning area
Primary Impacts ▪ 1 = Negligible, little to no damage
▪ 2 = Limited, some damage, loss of service for days ▪ 3 = Critical, devastating damage, loss of service for months ▪ 4 = Catastrophic, catastrophic damage, uninhabitable conditions Secondary Impacts ▪ 1 = Negligible, no loss of function, downtime, and/or evacuations ▪ 2 = Limited, minimal loss of function, downtime, and/or evacuations ▪ 3 = Moderate, some loss of functions, downtime, and/or evacuations ▪ 4 = High, major loss of function, downtime, and/or evacuation
Probability of Future Occurrences ▪ 1 = Unlikely, less than 1% chance of occurrence in next 100 years or has a recurrence interval of greater than every 100 years. ▪ 2 = Occasional, between 1 and 10% chance of occurrence in the next year or has a recurrence interval of 11 to 100 years. ▪ 3 = Likely, between 10 and 100% chance of occurrence in next year or has a recurrence interval of 10 years or less. ▪ 4 = Highly Likely, near 100% chance of occurrence in next year or happens every year.
The Federal Emergency Management Agency (FEMA) Local Mitigation Planning Handbook requires each agency to identify the magnitude/severity of each hazard to their infrastructure. The identification of hazards provided in Exhibit O-3 is highly dependent on the location of facilities within each agency’s jurisdiction and takes into consideration the history of the hazard and associated damage (if any), information provided by agencies specializing in a specific hazard (e.g., FEMA, California Geological Survey), and relies upon each agency’s expertise and knowledge. The table was created with input from the Water Emergency Response Organization of Orange County (WEROC), consultant staff, and IRWD. Changes to Risk/Vulnerability between IRWD and the Planning Area
Hazard
Justification for Concern Adjustment
The majority of IRWDs service areas is located outside of high fire hazard areas mapped within the planning area. Given the lack of resources in these fire prone areas, IRWD felt that the risk associated with wildfires was not as significant for their service area and impacts associated with these types of incidents would not impact them as greatly as other MAs and the planning area as a whole. While IRWDs service area is located within areas prone to significant seismic shaking many of their assets are located on earth materials that are considered more stable than in other parts of the planning area. In addition, IRWD has invested in retrofitting many of their assets to meet higher seismic standards reducing the vulnerability to this hazard. While power outages are a significant concern for the planning area, IRWD has invested in backup generation that has reduced their concern regarding this type of incident. In addition, past power outage incidents have not impacted IRWD in the same way as other MAs have been impacted.
Wildfire
Seismic Hazards: Seismic Shaking
Human-Caused Hazards: Power Outage
O-5
WSCP - 58
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