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By Jay Thorwaldson

If high-speed trains are tunneled, what would we do with all that dirt?

Uploaded: Mar 19, 2009

The realities of high-speed rail arrived in Palo Alto and the Midpeninsula this year -- even though the first train is years away.

Neighbors along the designated route, the Caltrain corridor, suddenly realized that they could be confronted with elevated tracks that could be a vertical or steeply sloped wall that might swallow up some private residences for a wider right-of-way.

Some civic leaders are pushing to get the high-speed tracks buried deep underground, using modern tunneling technology.

As the Weekly scrambled to cover all the emerging concerns and political positions, a friend asked me an interesting question last week when we were discussing possible alternatives, including tunneling:

"What would you do with all that dirt?"

Now that's a fair question. I immediately quipped that perhaps we could create a second Coyote Hill in the foothills.

Then I recalled a second big story this week: How a predicted rise in sea level this century of about 3 to 4 1/2 feet could expose vast areas of the South Bay to tidal flooding when a high tide teams up with a major 100-year flood. Such an event is misnamed. It actually means a flood or storm that has a 1 percent chance of occurring in any given year. Given climate-change predictions, such an event could occur, say, every decade or so.

In Palo Alto, a flood could extend as far inland as Middlefield Road mostly south of Colorado Avenue, along with other parts of Palo Alto along Bayshore Freeway.

But if that storm and high tide teamed up with an overflow surge down volatile, fast-rising San Francisquito Creek, then homes in northern Palo Alto become at-risk. Upstream, a series of steep, short canyons with historic names quickly feed storm runoff into tributary creeks, meaning San Francisquito can rise from a trickle to overflow within hours.

As for the threat from the bay, I recently came across an old news story I wrote in 1975 about a report that cited subsidence and erosion of levees all around the South Bay, creating an increased flood risk -- even without a rise in sea level.

The report estimated it would cost about $95 million to bring the levees up to where they once were and shore them up. That was 1975 dollars, of course -- the levees aren't the only thing that has eroded.

That work, as urgent as it seemed, was never done, to my knowledge, although levees have been patched up here and there. Instead of following the in-and-out outer levees of the old salt ponds, the engineers decided they should take a much shorter route and build a concrete wall (6 feet high, if I recall correctly) in the landward side of the marshes.

Palo Alto's section of wall would mostly run right along East Bayshore Road. Residents who loved their baylands views and their easy access to the marshlands toward the bay were appalled, and the plan died a slow, sodden death.

"Something there is that doesn't love a wall," famed American poet Robert Frost penned nearly a century ago. But his 1914 poem, "Mending Wall," is about two neighbors who ritualistically meet to repair and rebuild a New England stone wall that rabbit hunters or others have pulled down in places. It includes the famous line, "Good fences make good neighbors," an old saw even then that his neighbor liked repeating.

It was the wall around the bay that killed the levee project more than 30 years ago. And the absence of that project now may threaten thousands of South Bay homes with serious flooding if the sea-level predictions actually occur, as seems increasingly likely according to scientists studying global warming.

So now we face the prospect of a new wall, one to elevate the rails through Palo Alto and neighboring communities.

A full range of possibilities will be studied as part of a comprehensive environmental impact review of the high-speed rail project, as approved by voters statewide last November.

But residents along the tracks in Palo Alto and some other Midpeninsula communities are convinced that a vertical-sided "Berlin Wall" will turn out to be the least costly and most politically attractive alternative.

Some Palo Alto civic leaders are arguing in favor of deep-tunneling the trains, even though that may be vastly more expensive. They say building 600 to 700 housing units along the right of way could offset most of the added cost.

But that's presuming all four tracks (two for the high-speed trains and two for existing Caltrain commute and freight operations) are buried -- which might not be the case at all.

Rod Diridon, a member of the High Speed Rail Authority board, said it might be too costly to tunnel all four tracks, so the Caltrain tracks might remain on the surface much as they are today. But folks should remember that this is a 100-year project, and costs should be amortized over that timeframe -- including perhaps some extra millions of dollars for a deep tunnel (if environmentally feasible).

Diridon, speaking to the Palo Alto Rotary Club Monday (March 16), said while he isn't allowed to express a personal opinion about any specific alternative (due to federal regulations relating to environmental studies on the project) he is able to make the case for the high-speed trains. He cited their huge environmental advantages, their spotless safety record worldwide, their comfort and the fact that they could whiz a traveler back and forth between Los Angeles and San Francisco in just over 2.5 hours, one way. [His PowerPoint presentation is at www.PaloAltoOnline.com/news/show_story.php?id=11639 .

Diridon also cited potential environmental risks to deep tunneling, such as possible interference with underground aquifer flows.

Getting from one place to another in the Bay Area -- and in California generally -- has been a source of contention since the great growth spurt of the 1950s. Growing up in pre-freeway Los Gatos, I recall Sundays when traffic would back up six miles on two-lane roads filtering through town as folks headed for a day at the beach in Santa Cruz. And that's not even counting the terrible air pollution that would completely obscure the mountains flanking Los Gatos many days a year.

But nowhere has the getting-around issue been more intense and contentious than in Palo Alto and the Midpeninsula, fueled by America's love affair with the car and a jobs-to-housing imbalance as high as 2.5-to-1 in Palo Alto that has pushed people further and further away from jobs to find homes.

But back to the gritty issue of where to put all that dirt from a deep tunnel.

OK, let's take the biggest view possible: Let's use that dirt to fix the bayside levees to protect homes and businesses around the bay, at long last.

As for the elevated-tracks "Berlin Wall" idea, let's see what Robert Frost might say:

"Before I built a wall I'd ask to know

What I was walling in or walling out,

And to whom I was like to give offence."