Federal engineers say a major Pacific storm could cause the Prado Dam to fail – leaving much of Orange County flooded under six feet of water.
U.S. Army Corps of Engineers have recently raised the dam’s risk category from “moderate” to “high urgency.” Dr. David Rogers – a geological engineering professor at the Missouri University of Science and Tech, says engineers are worried because the dam is built on weak soil.
“Your structure is only as good as the foundation you build on. When you build on a foundation that is cohesion-less material, it doesn’t have any binder like clay – it’s all gravel, sand or silt – you don’t have that cohesion. You don’t have the binder.”
He says that means steady, fast-moving flood waters caused by a sustained heavy rainfall could case the dam to fail.
“We used to laughingly refer to Riverside County as the land of sugar levees. They look nice until you put water against them, and then they dissolve like sugar.”
He concurs with the Army Corp. of Engineers’ assessment that the dam’s flood control system urgently needs a major upgrade.
“It could use a lot more channel stabilization if it’s going to withstand a long-term overflow event … Orange County depends on this structure like no other. There’s no question about that. You cannot afford to not be conservative or ultra-conservative with Prado. It’s the kingpin structure that protects you from being underwater.”
Dr. David Rogers was a guest on the Morning Drive.
By Sandy Wells
KABC News