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Virtual pipeline's southern California debut
averts economic crisis
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| The Port
of Oakland’s roadways could one day be as congested
as those linking the Long-Beach-Los Angeles port complex,
relieved by the newly completed Alameda Corridor Project Authority
transit line. Partnering with Alex Horne (pictured here) and
key to his project’s research was the work of doctoral
students James Hauri, Marc Beutel, Jennifer Rubrake, and several
undergraduates, as well as his long-time collaborator Berkeley
alumnus Larry Russell, and Dr. James Roth, now a private consultant
in San Francisco, formerly at the Richmond Field Station.
Photo: Peg Skorpinski |
By Susan Davis
This is environmental chemistry in action," says Berkeley
civil and environmental engineer Alex
Horne, speaking of the newly launched Alameda Corridor Line Project—a
20-mile, $2.4 billion railroad track from Long Beach to Los Angeles
completed in April.
"The first freight trains began rolling in the spring, and
with them, Governor Gray Davis predicts that California’s
gross national product will surpass Great Britain’s to become
the fifth largest economy in the world," says Horne, referring
to his native England. In this instance, the new line links the
huge Long Beach-Los Angeles port complex with the major railheads
of downtown Los Angeles. "Amazingly, the $157 billion worth
of freight moved every year in the past by trucks is expected
to double in the next few years now that it can be moved by rail,"
says Horne.
For years, a daily procession of thousands of diesel-powered trucks
have been hauling shipping containers through crowded city streets.
In winter 2000, massive excavations of a new 10-mile (33-foot
deep, 50-foot wide) lined, concrete transit trench for a rail
line were in full swing. The trench promised to solve the congestion,
but there were some real problems. "Apart from the numerous
construction and geotechnical challenges," says Horne, "out
of the blue there appeared a severe environmental restraint that
hopelessly stalled the project."
Groundwater seeping into the track’s trench was too salty
to be pumped into the local Los Angeles River, and too laden with
heavy metals to be put into the Los Angeles estuaries, home to
fragile marine animals. "Marine animals are more sensitive
to toxicity from metals like copper than their freshwater counterparts,"
Horne says.
Underwritten with state bonds, if the project remained stalled,
the funding would default, significantly lowering the credit rating
of the entire state. What’s more, says Horne, each day of
stopped work cost the state $500,000 in interest, while up to
17 million gallons of water a day emptied into the trench. "A
two-year delay was forecast, and the bonds were to default in
three weeks. My students and I used an ecological engineering
approach and solved the problem in a week," says Horne, whose
research on aquatic systems is internationally known, not to mention
his widespread reputation for what he calls "fig leaves,"
or simple solutions to difficult problems where crisis is smoldering.
Had there been more time, says Horne, a large pipeline for the
groundwater could have been built across the city and into the
ocean, where sea water would dilute the heavy metals to safe levels.
But that was not to be.
Two years ago, Horne and his doctoral student team were studying
natural detoxification of copper sediments in Strawberry Creek
on campus. There, they discovered that organic matter in water
detoxifies heavy metals through "chelation," a natural
process that occurs when an organic molecule grabs the free toxic
metal, much like a crab’s pincers grabbing food. Horne realized
that chelation could bind the heavy metals in the trench’s
groundwater. Once the heavy metals were inactive, the "safe"
water could flow through existing channels to the estuary and
out to the ocean. "You can chemically chelate the metals,
rendering them non-toxic. In effect," he says, "the
time-consuming construction of a new pipeline to carry the wastes
away could be instantly replaced with a ‘virtual pipeline.’"
Rather than natural chelators, like citrate or dead leaf extract,
Horne and his team used ethylene-diamine tetra-acetic acid (EDTA),
a common ingredient in skin creams, and the strongest artificial
chelator available. EDTA would bind the metals more tightly, Horne
explains, as well as resist decomposition by bacteria and sunlight
for a longer time.
Anyone passing through this area of southern Los Angeles County
near Watts or Compton knows that it’s not exactly pristine
wilderness— the estuary, which runs through the Dominguez
Channel, passes through areas that have seen a hundred years of
oil refining and auto manufacture. The heavy metals deposited
in the sediments make it one of the state’s most polluted
"hot spots." "You can’t imagine a more disconsolate,
seemingly non-living system," Horne says. "But marine
animals, including oysters, do exist there and we monitored them
extensively. The good news is that EDTA had no harmful effect
on these indigenous animals."
Despite the project’s completion, Horne wanted to further
assist the polluted estuary. "I proposed that for every pound
of chelated groundwater metal passed through, that the agency
overseeing the project pay for the removal of 1.5 pounds of the
polluted estuary’s sediments. I like to fix things,"
Horne says, "not just come up with computer models and theories.
It’s a chance to do some good old-fashioned engineering
with a new twist."
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