html xmlns="" xml:lang="en" lang="en"> From the archives: Good design for a real problem.

Thursday, September 28, 2006

Good design for a real problem.

Flood fighting class was great. There was a disappointing lack of jargon, but a ton of technique. You know, it was all technique that would have occurred to me after my third wave protection plastic tarp washed away, like facing the seams and folds downstream instead of into the current. But honestly, it would have taken me the first hundred sandbags to learn to throw the first shovelful on the lip of the bag to anchor it before throwing the next three shovelfuls in, from a safe distance from your partner’s hand. There is so much technique to moving in the physical world. When you tie off a sandbag, would you have thought to hold it by one corner and spin it until the cloth doubles over and becomes easy to tie? Again, after doing it the hard way for a hundred sandbags, I would have immediately recognized the better way when I saw it. But I don’t know when I would have thought of it.

Some interesting things from the class:

  • Incompetent and bungling as we were, sandbagging goes shockingly fast. It must be astonishing to watch a crew with a few days’ practice; like fast motion film, but not.
  • If water is channeling through a levee, it will come out the other side in a boil. A boil running clear is not a problem. Levees can seep or even tunnel like that for decades. If the boil is carrying material, which you might see as a little volcano building around the boil, it is scouring the inside of the levee. That’ll grow until the levee collapses.
  • So how do you stop a dirty boil? Again, I would never have thought of this; I would have filled a sandbag and plugged the boil. But no, you never stop a running boil; the water inside the levee will find a new exit. Instead, you put a ring of sandbags around it and let the water fill that. Increase the height of your sandbag ring to decrease the difference in head between waters on the two sides of the levee. Stop when the water from the boil runs clear but before you stop the running water entirely. Leave a small spillway for water to drain from your sandbag ring.
  • Environmental damage from the gold mining days is still causing trouble. The bed of the Sacramento River was raised several feet for much of its length. Levees built on sands washed down from hydraulic mining are being eaten from the bottom. 140 year old decisions are active problems.

A scary thing from the class:

The guys who taught the class are old school engineers and maintenance guys. They have bellies and they can drive heavy machinery and they make jokes about the enviros. They are tremendously competent at things that impress me, like driving stakes or tying fast hitches. They are pragmatic and know their landscapes and they are largely unimaginative. I absolutely trust them to run crews in a cold rain in the middle of the night, there to save me and mine. Those guys? They are scared and angry at the new development going up in California. They say things like “That levee at that bend is gonna fail everytime. It’ll never hold, but now there’re six thousand new houses behind it.” “I don’t know what we’re gonna do, ‘cause last time we could break out a spillway there, but now… all the new houses… .” “Where we’re gonna get the machinery to protect all those places at once, I don’t know. But we’re gonna have to, if it isn’t farmland any more.” They are not Democrats and they are not environmentalists. But they hate the sprawl behind levees and they make me scared too.


Blogger Megan said...

Hey t_n, could you please email me? I don't have a way to reach you...

7:43 AM  
Anonymous ptm said...

A number of my buddies are mechanics of various stripes. They've long since accepted my mechanical ineptitude, and now help me with a chuckle and no "you can't do that?"

That closer is scary.

12:17 PM  

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