Flood Protection Sandbags with flooded buildings in background

Significant Flood Event Threatens Southern California Facilities

  May 22, 2019

By Dan Hounsell

Emergency preparedness for institutional and commercial facilities involves identifying and preparing for crises of all sorts, often without knowing the exact location of the potential problem. In the case of a looming emergency in Southern California, finding the source of the crisis is not the problem. Stopping it is.

Federal engineers are raising alarms that a “significant flood event” could compromise the spillway of Southern California’s aging Prado Dam and potentially inundate dozens of Orange County communities from Disneyland to Newport Beach, according to The Los Angeles Times.

After conducting an assessment of the 78-year-old structure earlier this month, the U.S. Army Corps of Engineers announced it was raising the dam’s risk category from “moderate” to “high urgency.”

Lillian Doherty, the Army Corps’ division chief, says her agency is working with a national team of experts to develop interim and permanent risk-reduction measures at the dam, as well as public outreach strategies to alert the estimated 1.4 million people who live and work in 29 communities downstream.

In February 2017, a concrete spillway at the Oroville Dam disintegrated during heavy rains and triggered the evacuation of more than 180,000 people. That same year, the Corps of Engineers discovered that the 60-year-old Whittier Narrows Dam, about 40 miles to the west of Prado Dam, was structurally unsafe and posed a potentially catastrophic risk to more than 1 million people.

In that case, engineers found that intense storms could trigger a premature opening of that dam’s massive spillway, swamping homes, schools, factories and roads from Pico Rivera to Long Beach. Engineers also found that the earthen structure could fail if water were to flow over its crest.

The Corps estimates it will cost roughly $600 million in federal funds to upgrade the Whittier Narrows facility, which has been reclassified as the agency’s highest priority nationally because of the risk of “very significant loss of life and economic impacts.”

Dan Hounsell is editor-in-chief of Facility Maintenance Decisions.



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