Uncivil Engineering 3: Canal or tunnel?

Since publishing an earlier post on the possibility of a tunnel alternative to a peripheral canal new information has emerged, suggesting that another post is in order.

This post explores two options, both of which are unacceptable to some, expensive, and possibly what there is to choose from for all. Think of what follows as a lesser-of-two-evils thought experiment.

An image of a tunnel from Granny Buttons, a blog and a good way to enter into the community of canal enthusiasts. The DNP hopes that the Canal option is at least given its due, if only because the alternative may be even worse.

A recently completed Swiss rail tunnel project totaling over 93 miles (two tunnels, each over 45 miles) cost 7.2 billion USD. The length of the Swiss tunnel is very close to the length of a possible through-Delta tunnel.

It is clear that the tunnel option is being seriously considered. This Delta Habitat Conservation and Conveyance Program comparison of the two isolated conveyance options and the tunnel is illuminating.

Conclusions? The eastern isolated conveyance (the Peripheral Canal), the preferable of the two surface alternatives, is less expensive and less of a technological risk. But the tunnel is more viable politically because building a structure no one will ever see makes it ostensibly less environmentally impactful and greatly reduces necessary land takings, something that will no doubt be bitterly contested.

The DHCCP estimates that the difference in cost between the two to be about 1.5 billion. It would not surprise the DNP if the cost differences are described essentially as a wash, because the litigation associated with land takings may end up making it so.

But would the tunnel really be a better alternative from a strictly environmental perspective? Yes, it would certainly bring far less change to the surface of the Delta. But of course, as a development, damaged land would have to be mitigated by “restoration” of an equal amount of habitat, so one might argue that a canal would do no damage to the Delta’s habitats. So the argument against the canal doesn’t hold up as an environmental argument. A private property, or a preservation one, yes - but not an environmental argument.

The DNP still awaits a careful study of how a canal along the eastern edge of the Delta might actually improve Delta water quality. A post back in August described a project called a siphon spring. A siphon spring would be a device and a place. Here is a diagram of how a Canal would inject water into an existing waterway:

The device would redistribute a portion of the diverted Sacramento River water in the Peripheral Canal back into the various intersecting rivers and sloughs (Cosumnes, Mokelumne, San Joaquin, etc.) as it passed by. In theory, this might significantly improve the quality of water for the Delta’s aquatic plants and animals. We hope that the soon-to-be-announced independent scientific panel will take on this question.

As places, the siphon springs would be opportunities to develop recreational, tourism, and other activities and commodities. The springs would become places of common public use and pleasure.

The ability to imagine canals, tunnels, dams, levees, and the rest is controlled by the narrow views of technocrats and politicians. To them, imagination is a risk, an unknown best avoided. This is why the tunnel is likely to be the solution. Even the Delta’s tenacious preservationists will have a hard time justifying their opposition to such a perfectly banal, functional, solution.