A perspective from Oregon’s mid-Willamette Valley

What’s up at Folsom Dam?

Written May 5th, 2014 by Hasso Hering

folsom damIf you’re traveling on Interstate 5 the next two nights, you might see a huge truck carrying equipment south. ODOT announced the oversize trip on Monday. And it’s more interesting — to me anyway — than just a big rig going down I-5. The truck, 137 feet long, two lanes wide and more than 14 feet tall, will carry two spillway gates bound for Folsom Dam on the American River northeast of Sacramento.

It will enter Oregon via the Glenn Jackson Bridge across the Columbia, take I-205 to I-5 and then head south. It’s allowed to run only between 10 p.m. and 5 a.m., and on Wednesday it is expected to spend the day parked at the Oak Grove rest area near Harrisburg.

This is of more than passing interest because ODOT says that “as many as 10 more loads bound for the Folsom Dam are planned for this spring and summer.” So what’s going on at Folsom Dam?

It turns out that the federal government and several California agencies are working on a project to raise the complex of dikes and dams there by 3.5 feet in order to better protect the Sacramento area from a flood of the kind that might happen once every 200 years. Evidently they don’t think the chronic water shortage in the Central Valley or the current severe drought are going to last forever.

The Sacramento Business Journal said in story on March 14 that the overall project is estimated to cost $802 million. It identified the chief contractor as Granite Construction, the same California company that had the first contract on the big Highway 20 project in the Oregon Coast Range near Eddyville.

Government online documents on the California project call it the “Folsom Dam Raise,” suggesting a new pattern for the use of verbs in fed-speak. In Nevada recently, they called the roundup of Cliven Bundy’s cows a “cattle gather.”

One more item worth noting. It was at Folsom Dam that, in July 1995, a spillway gate collapsed as it was being opened, resulting in the sudden release of much of the reservoir down the American River at the rate of 40,000 cubic feet per second. Once the failure was analyzed and understood, the Corps of Engineers started repairing spillway gates all over the place, including in recent years at Foster Dam in Linn County and other dams in the Willamette drainage.

What caused the failure at Folsom, after about 40 years of safe operation, was vibration caused by friction at the trunnion or pin on which the gate turned. Investigators concluded that the government had switched to a more environmentally friendly grease — it had  no lead like the old one — and cut back on the frequency of maintenance because of budget issues, something the Corps designers of the gates in the 1950s could not have foreseen.

After the 1995 failure, the broken gate was replaced and the others beefed up. Now, apparently, new ones are being installed. (No, that’s not true, I found out. See my reply to a commenter below.)

And why are they being trucked down through Oregon? When a “bulkhead gate assembly” arrived there in March, someone explained to the Sacramento reporter that when the load reached Vancouver, Wash., evidently on a vessel, it was cheaper and less complicated to send it from there by truck than to route it through the nearest California ports. (That’s a false assumption, too, I discovered. The gates are made by Oregon Iron Works in Clackamas and assembled at the company’s Vancouver, Wash., site. The company says that transporting them to California — by barge to Stockton  and then taking to the dam on trucks — would have been more expensive than trucking them down the freeway.)


2 responses to “What’s up at Folsom Dam?”

  1. Greg Burbach says:

    Raising the dam sounds like a government boondoggle, but, my question is, where are the spillway gates being built? Somewhere overseas? China? I hope NOT.

    • Hasso Hering says:

      Thanks for asking. You’ll be happy to learn, as I was, that the gates have been manufactured under a $45 million contract by Oregon Iron Works of Clackamas. The company posted a thorough explanation of the whole Folsom Dam project at http://www.oregoniron.com/news-and-announcements/installation-of-new-floodgates-to-begin-soon-on-1b-folsom-dam-project/. I wish I had seen that before I wrote the commentary. I would have avoided some mistakes and false assumptions. The new gates are not to replace existing ones but will be installed in a new spillway, some 50 feet lower than the ones on the main dam, to enable the dam operators to spill more water faster in the event a big flood makes it necessary to avoid the reservoir overtopping the dam. (hh)


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