While everyone is justifiably fretting and fussing over the subpar ironware on the new Bay Bridge, another infrastructure problem looms even larger.
The Sacramento/San Joaquin Delta is crisscrossed with levees that protect farms and cities. Trouble is, virtually all are in dire disrepair, and several have broken in past years, leading to local flooding. But the problem is bigger than an occasional breach and the temporary submerging of an asparagus field or farmhouse. The U.S. Geological Survey maintains there is a 63 percent probability of an earthquake registering 6.7 or greater in the Bay Area and Delta over the next 30 years, and one big shake on the San Andreas or Hayward faults could cause immediate levee failure across the entire Delta. This would allow salt-water intrusion to the giant state and federal pumps that supply the South State with water. Los Angelenos could be taking sponge baths for months.
Governor Jerry Brown’s administration announced a Very Big Fix for this Very Big Problem. It’s also a Very Expensive Fix. Hamed Hamedifar (PhD, 2012, CEE), an Infrastructure Engineering Research/Postdoctoral Fellow in Civil Engineering, has a simpler solution. One, he says, that is easier and cheaper.
The Brown plan is for Twin Tunnels, two huge pipes buried under the Delta that would shunt water south from the Sacramento River. Even if the Delta’s levees all failed catastrophically, water would still flow to the L.A. Basin and the farmlands of the San Joaquin Valley.
Opponents say it would hasten the ecological decline of the Delta and saddle Californians with ruinous debt; price tag estimates range from about $30 billion to $60 billion. It would be far cheaper and less disruptive, say Tunnels critics, to simply re-enforce existing levees. But until recently, specifics on just how to do that were vague.
Hamidifar is not vague.
“We ran computer analyses on 65 levee sites between Yuba City and Stockton,” Hamedifar observed in a recent phone chat, “and we found that the piles increased levee stability at all sites. Sometimes the improvement was great, sometimes it was moderate – but all the sites showed significantly more stability.”
Installation of the plates would proceed in an expeditious and cost-effective fashion if the State green-lighted the idea, Hamedifar said.
“You could complete a typical project, from permitting to installation, in about 10 days. Costs are about $1 million per mile.”
There are 1,110 miles of levees in the Delta and 2,100 miles in the San Joaquin Valley, so it would cost $3 billion and change to retrofit them all with pier plates – exponentially less than the price tag of the Twin Tunnels.
One might think that government engineers and bureaucrats would welcome that news with popping champagne bottles and funny hats. But nope.
“Richard Short and I made presentations to both the California Department of Water Resources and the U.S. Army Corps of Engineers,” Hamedifar says. “We asked for feedback, but they had no complaints, couldn’t point out any flaws in the technology. But it was clear they weren’t interested—they were obviously determined to focus on another solution.”
That kind of tunnel (or Twin Tunnels) vision probably won’t resolve the Delta’s dilemma, Hamedifar says.
“It’s always risky to push just one solution for an engineering problem like this, especially if the idea being pushed isn’t demonstrably better than other ideas,” he says. “It’s likely you’ll need a multitude of approaches, not just one. The Tunnels will involve huge fiscal and environmental costs, and they’ll take years to complete. Our approach is cheap and effective, and it can be done quickly. We think it at least deserves a fair hearing.”
— Glen Martin
Posted on May 16, 2013 - 1:36pm