Seismically-repairable, river-protecting levees

Jeff Michael at the Valley Economy blog is disseminating a preliminary executive summary of a Delta Economic Sustainability Plan that is being produced under (I think) his direction.

The ESP (like the acronym) is a thorough counter argument to the pro-Peripheral Canal/Tunnel argument that says it is too risky to continue to use the Delta’s waterways (and the levees that protect them) as the way to move water to the pumps. It is an alternative that deserves testing, and to their credit, they have found a great site to do just that.

More about this below, but first, a few words about why levees interest me so - as artifacts, as works of design, yes - but especially as sites of contention.

It’s an irony of the tensions of scale at the heart of debates over the Delta’s future: for local people, the levees protect land, and the water is a threat; but for the water export constituencies, the levees protect the rivers and sloughs, insuring safe passage of their precious cargo to the pumps. To them, the Delta’s land is the threat, and is to be entirely avoided, literally circumvented. This issue of scale makes people see different things in the same reality.

One person’s land-protecting levee is another’s river-protecting levee. This engineering firm’s is “seismically-repairable”:

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Though not as invulnerable to a big seismic event (nothing is completely), upgrading hundreds of miles of levees as studied by the ESP is a far less expensive alternative to the canal or tunnel. Professor Michael shares a link to the thinking behind Dr Robert Pyke’s levee engineering ideas at a well done piece at The California Spigot.

The cross section above is very similar to the one developed by the owners of Lower Jones after the 2004 Upper Jones levee breach.

The state’s fiscal woes are extreme, and its dysfunctional 1/3 majority governance system has only exacerbated the many pressing needs of people who desperately depend on shrinking government services.

So I basically concur with the idea that reinforcing levees is the most practical and cost-effective way to provide a maximum of water supply security, environmental stabilization, and Delta preservation. This premise is at the heart of the Delta-specific development post I wrote a couple of days ago, and to which I will soon return, impractical, blue-sky optimist that I am about change in the Delta.

This levee cross section is only one typology, and probably the least disruptive one of what will likely be many. Because they function in complex ways and support flood control, water supply and habitat creation imperatives, I think setback levees should be used in all areas with no significant disruptive impacts to settlements.

But it is where there are significant impacts that the real test of the Reinforced Delta strategy lies.

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According to Professor Michael’s post, his group will be “developing a visual concept of what the recreation strategy could mean for a detailed area in the Delta.” I understand that this concept will test the implications of FEMA’s recent upgrade to 100-year effectiveness to levees in the Locke/Walnut Grove area. This should also provide grist for debate over whether flood control, environmental improvements and historic preservation can coexist in an affordable way. Assuming of course that the levees there do not already meet the FEMA specs, and it’s very possible that they do.

In many historically precious places (which have economic value, too) like Bacon Island’s Farm Camp Number Three, Locke and Walnut Grove, and the towns of the North Delta, settlements are on the crest, on or very near to the inside slope of the levee. It will be interesting to see whether if necessary consideration is given to moving the entire settlement back from the levee’s inside slope. Expensive proposition.

Similar to dealing with the expense of environmental regulation, it will be interesting to see whether there is political will to spend the money necessary to walk the walk when it comes to preserving these delicate places. Especially in the face of Tea Party demagoguery.

 

 

Posted by John Bass on 18 Aug 2011 | Comments (1)

Comments

Fantastic write-up, continue the good work!

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