2020 Local Hazard Mitigation Plan

City of Irvine

Dam Failure

Physical Threat

Various factors, such as the amount of water released, the distance between the dam failure site, and the topography of the surrounding land, all influence the extent to which physical assets in Irvine are threatened. Some reservoirs, like Peters Canyon Dam or San Joaquin Reservoir, simply hold less water or are in remote locations that reduce the threat to physical assets in the City. Other reservoirs, like Villa Park Dam or Santiago Canyon Dam, have large storage capacities that could potentially lead to widespread inundation or large areas of northern Irvine if the reservoir waters are released due to a dam breach. Figure 4-2 shows which CFs and FOC would be impacted in each dam failure scenario. Table 4-3 identifies the physical assets in Irvine that are threatened by the potential failure of the following dams:

Peters Canyon Dam Rattlesnake Canyon San Joaquin Reservoir

Sand Canyon Spillway

•

Santiago Dam Syphon Canyon

•

• Villa Park Dam If any of these dams were to fail at maximum capacity and release the water contained in its reservoir, it would threaten a variety of CF and FOC in Irvine. Sand Canyon •

Table 4-3: Critical Facilities and Facilities of Concern (Dam Failure) Dam Inundation Area City Vital Operations City Community Centers City Resident Services City Recreation Support Bridges Schools*

Potential Loss**

FOC

Peters Canyon Dam Rattlesnake Canyon San Joaquin Reservoir Sand Canyon Sand Canyon Spillway

$ 1,821,720

$ 47,819,834

$ 27,053,460

$ 31,225,500

$ 30,598,520

Santiago Dam Syphon Canyon Villa Park Dam

$ 73,404,574

$ 42,675,657

$ 68,922,471

* Replacement Values unavailable

** Based on the City of Irvine insured replacement values

Based on this analysis, the greatest number of facilities impacted by dam inundation would occur as a result of a failure of either Rattlesnake Canyon or Villa Park Dam, both of which could affect 32 facilities within the City. Based on the potential loss estimates, the greatest potential loss could occur from the failure of the Santiago Dam, which could damage infrastructure valued in excess of $73 million.

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