Archive for the ‘Oakland hazards’ Category

Central Reservoir

8 April 2013

Central Reservoir is operated by EBMUD, but it’s much older. It’s the weird-looking steel-covered field north of Sausal Creek. This is a view looking over the reservoir from Ardley Avenue toward the hills.

centralrestop

That’s the Altenheim on the left, across I-580, and of course the LDS temple with Redwood Peak behind it.

The reservoir was built in 1910 by the People’s Water Company, which took the existing valley of a Sausal Creek tributary, hollowed out the top of its watershed and made an earthen dam. Later EBMUD assumed control of it and upgraded things considerably. However, landslides plagued the steep west bank of Sausal Creek directly east of the reservoir starting in the 1930s.

The latest set of slides, in 2006, led to a tangle of lawsuits initially aimed at EBMUD and blaming leakage from the reservoir. The lawsuits were consolidated and went to a jury trial in 2012, with Alameda County as the main defendant and the damaged land owners (two homeowners and a church) as the remaining plaintiffs. The jury found for the County. None of the media that announced the lawsuit bothered to report the outcome, and the City of Oakland hasn’t bothered to clear EBMUD’s name, but the jury dispensed justice as designed.

For 17 MB of geotechnical detail, see EBMUD’s Central Reservoir Seismic Final Report, issued in 2008. As far as engineers can tell, even the Big One on the Hayward fault won’t break the dam. But if I lived downstream, I’d keep a close eye on the dam after a truly major quake and be ready to relocate. And in the aftermath, that emergency water supply may save our lives.

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Headwater landscaping

26 March 2013

The advantage of living in the highest hills is that there’s no one upstream from you. At the same time, hilltop dwellers may find it easy to forget what it’s like downstream.

gravelwash

This lot sits at the head of a stream valley at the edge of a regional park. The large expanse of impermeable pavement collects rainwater, and the terrace above it discharges more runoff in a large drainpipe. Ordinarily the ground would absorb most of the water and release it gradually, the way that trees are used to. Instead the flow that results here is strong enough to carry away a lot of gravel. Oh well, call in another truckload.

Turn around and track that water and gravel over the property line into the Regional Open Space. With the extra water, the stream is already cutting a deeper channel into its valley. As the years go by, the valley walls will slump into the stream and the trees will fall with them. A big wad of sediment now working its way downstream will clog the habitat below, smothering the bottomland and its ecosystem. Meanwhile the erosion of the stream valley will work its way headward. Eventually, within a lifetime, the spreading collapse will reach the edge of this large lot (and the neighbors’ lots) and whoever owns it will have an expensive problem. This pristine street may disappear from the map, like others before it in the Oakland hills.

I’m not giving a professional opinion here; it’s obvious to common sense. The landscape of the hills is fragile, but expert advice can make living there much more sustainable.

The fire zone

20 October 2011

oakland hills fire

I was across the bay on October 19, 1991, doing a freelance job at some client whose name I forget. It was a hot day, and I saw a tall plume of smoke in the Oakland hills. The fire people worked on it, and that evening as I headed back across the bay it seemed to be over. But the following day, 20 years ago today, an ember got loose and took out a huge swath of the hills with some three thousand homes on it. It was a terrifying day, like something out of Lord of the Rings. Thick smoke covered the whole sky, and the east wind wouldn’t let up. The city was at nature’s mercy until the winds turned, late in the afternoon. For years afterward we would find pieces of charred wood in our garden that had dropped from the sky that day.

Apparently the same thing had happened in 1970. Historians reminded us that it happened in 1923, too. Before that the native inhabitants made a practice of torching the hills often to keep the land clear. But in the aftermath of 1991 the hills were hastily repopulated and reforested by residents whose driving urge was to make the pain stop. They had the eager help of insurance companies, placing their bets on the enduring value of view lots.

Today these fireprone hills are platted out for houses forever, even the impossible slopes of Charing Cross Road. Now the hills are in an unsustainable cycle of building expensive homes cheek by jowl on inadequate streets, growing inertia as fuel builds up and preparations lapse, one dire day of conflagration, and heedless rebuilding. The earthquake cycle is just a slower version of this fire cycle. If madness is doing the same things in the face of futility, then Oakland has gone mad. It doesn’t have to be this way.

Water underground

4 January 2011

In today’s Chronicle, the Oakland writer Jon Carroll was musing about fire: “Usually it’s an obedient little creature, about the size of a cocker spaniel—until one day it turns into the largest, meanest cocker spaniel on Earth, and there goes the house.” Water, another of the four ancient elements, is the same way.

water main burst

Water is great in metered doses, delivered by tank and faucet. But “water dissolving, water removing” is no tamer than fire. Some time you should see firsthand what keeps it constrained: giant dams and stout mains, treatment plants, intricate feeder lines. The antique examples of dams and treatment facilities in Oakland are not the state of things today. Every now and then something breaks, like this line under Santa Clara Avenue in 2005, and a hint of chaos leaks out.

Last week a handyman had our water turned off for most of the day, with no word about when he would finish. As sunset approached we panicked enough to go out and buy 48 pounds of jugged water. But we didn’t need to use most of it. And so another bit of our earthquake preparedness is in place, a little lurch of progress. After the next big-enough one there will be water, water everywhere.

The ancients had a handle on things with their notion of four elements. Fire and water are worthy of the status, both full of motion and power. As for air, every weather report vouches for it. But it took someone more observant than most of us to see earth the same way and sum it all up as panta rhei, everything flows.