Dams – BLDGBLOG

Voids and Vacuums

[Image: Google Maps view of Mosul Dam (bottom center) and the huge reservoir it creates].

Dexter Filkins—author of, among other things, The Forever War—has a long new piece in the first 2017 issue of The New Yorker about the impending collapse of Iraq’s Mosul Dam.

The scale of the potential disaster is mind-boggling.

If the dam ruptured, it would likely cause a catastrophe of Biblical proportions, loosing a wave as high as a hundred feet that would roll down the Tigris, swallowing everything in its path for more than a hundred miles. Large parts of Mosul would be submerged in less than three hours. Along the riverbanks, towns and cities containing the heart of Iraq’s population would be flooded; in four days, a wave as high as sixteen feet would crash into Baghdad, a city of six million people. “If there is a breach in the dam, there will be no warning,” Alwash said. “It’s a nuclear bomb with an unpredictable fuse.”

Indeed, “hundreds of thousands of people could be killed,” according to a UN report cited by Filkins.

What’s interesting from a technical perspective is why the dam is so likely to collapse. It’s a question of foundations. The dam was built, Filkins writes, on rock “interspersed with gypsum—which dissolves in contact with water. Dams built on this kind of rock are subject to a phenomenon called karstification, in which the foundation becomes shot through with voids and vacuums.”

Filling those voids with grout is now a constant job, requiring dam engineers to pump huge amounts of cementitious slurry down into the porous rock in order to replace the dissolved gypsum.

[Image: Mosul Dam spillway; photo by U.S. Army Staff Sgt. Brendan Stephens].

At one point, Filkins goes inside the dam where “engineers are engaged in what amounts to an endless struggle against nature. Using antiquated pumps as large as truck engines, they drive enormous quantities of liquid cement into the earth. Since the dam opened, in 1984, engineers working in the gallery have pumped close to a hundred thousand tons of grout—an average of ten tons a day—into the voids below.”

Finding and caulking these voids, Filkins writes, is “deeply inexact.” They are deep underground and remain unseen; they have to be inferred. The resulting process is both absurd and never-ending.

The engineers operating [the grout pumps] can’t see the voids they are filling and have no way of discerning their size or shape. A given void might be as big as a closet, or a car, or a house. It could be a single spacious cavity, requiring mounds of grout, or it could be an octopus-like tangle, with winding sub-caverns, or a hairline fracture. “We feel our way through,” [deputy director Hussein al-Jabouri] said, standing by the pump. Generally, smaller cavities require thinner grout, so Jabouri started with a milky solution and increased its thickness as the void took more. Finally, after several hours, he stopped; his intuition, aided by the pressure gauges, told him that the cavity was full. “It’s a crapshoot,” [civil engineer Azzam Alwash] told me. “There’s no X-ray vision. You stop grouting when you can’t put any more grout in a hole. It doesn’t mean the hole is gone.”

It’s hard not to think of a scene in Georges Perec’s novel Life: A User’s Manual, a scene I have written about before. There, a character named Emilio Grifalconi picks up an old, used table only to find that the support column at its center is “completely worm-eaten.” Slowly, painstakingly, operating by intuition, he fills the worm-eaten passages with a permanent adhesive, “injecting them with an almost liquid mixture of lead, alum and asbestos fiber.”

The table collapses anyway, alas, giving Grifalconi an idea: “dissolving what was left of the original wood” in order to “disclose the fabulous arborescence within, this exact record of the worms’ life inside the wooden mass: a static, mineral accumulation of all the movements that had constituted their blind existence, their undeviating single-mindedness, their obstinate itineraries; the faithful materialization of all they had eaten and digested as they forced from their dense surroundings the invisible elements needed for their survival, the explicit, visible, immeasurably disturbing image of the endless progressions that had reduced the hardest of woods to an impalpable network of crumbling galleries.”

Whether or not such a rhizomatic tangle of grout-filled chambers, linked “voids and vacuums” like subterranean grapes, could ever be uncovered and explored beneath the future ruins of a safely dismantled Mosul Dam is something I will leave for engineers.

[Image: Mosul Dam water release; photo by U.S. Army Staff Sgt. Brendan Stephens].

However, Filkins points out one possible solution that would sidestep all of this: this option, he writes, “which has lately gained currency, is to erect a ‘permanent’ seal of the existing dam wall—a mile-long concrete curtain dropped eight hundred feet into the earth.”

This would not be the only huge subterranean wall to be proposed recently: think of the “giant ice wall” under construction beneath the Fukushima nuclear power plant in Japan: “Japan is about to switch on a huge refrigeration system that will create a 1.5-km-long, underground frozen ‘wall,’ in hopes of containing the radioactive water that’s spilling out of the Fukushima nuclear power plant, which went into meltdown following the earthquake and tsunami of March 2011.”

The Dam Industry’s Chernobyl

There’s an alarming new piece up at The New Yorker looking at two potential dam failures, in Iraq and Zambia, and the extraordinary effects these disasters would have. The collapse of Iraq’s Mosul Dam, for example, which the U.S. Army Corps of Engineers calls “the most dangerous dam in the world,” “could drown as many as five hundred thousand people downstream and leave a million homeless.” The collapse of Zambia’s Kariba Dam, meanwhile, and the resulting megaflood would be “the dam industry’s Chernobyl”: “three million people live in the flood’s path; most would die or lose their crops or possessions. About forty per cent of the electricity-generating capacity of twelve southern African nations would be eliminated.” (Spotted via @waltonwater)

N.A.W.A.P.A.

With drought on my mind, it was interesting to come across two new articles in The New York Times today, both about the United States of waterlessness.

The less interesting of the two tells us that “[w]ater levels in the Great Lakes are falling; Lake Ontario, for example, is about seven inches below where it was a year ago” – and, “for every inch of water that the lakes lose, the ships that ferry bulk materials across them must lighten their loads… or risk running aground.”

[Image: The Great Lakes are draining; photo by James Rajotte for The New York Times].

What’s causing this? “Most environmental researchers,” we read, “say that low precipitation, mild winters and high evaporation, due largely to a lack of heavy ice covers to shield cold lake waters from the warmer air above, are depleting the lakes.”

I’m reminded of something Alex Trevi sent me several weeks ago, in which writer and comedian Garrison Keillor speculates as to what might happen if the state of Minnesota sold all the water in Lake Superior.

Keillor describes a fantastical project called Excelsior, in which the Governor of Minnesota “will stand on a platform in Duluth and pull a golden lanyard, opening the gates of the Superior Diversion Canal, a concrete waterway the size of the Suez. Water from Lake Superior will flood into the canal at a rate of 50 billion gal. per hour and go south.”

It will flow into the St. Croix River, to the Mississippi, south to an aqueduct at Keokuk, Iowa, and from there west to the Colorado River and into the Grand Canyon and many other southwestern canyons, filling them up to the rims – enough water to supply the parched Southwest from Los Angeles to Santa Fe for more than 50 years.

The drained landscape left behind will be renamed the Superior Canyon – and the Superior Canyon, Keillor says, will put the Grand Canyon to shame. “It’s bigger, for one thing,” he writes, “plus it has islands and sites of famous shipwrecks. You’ll have a monorail tour of the sites with crumpled hulls of ships. Very respectful.”

By 2006, Keillor speculated (he was writing from the Hootie & the Blowfish-filled year of 1995):

Lake Superior will be gone, and its islands will be wooded buttes rising above the fertile coulees of the basin. A river will run through it, the Riviera River, and great glittering casinos like the Corn Palace, the Voyageur, the Big Kawishiwi, the Tamarack Sands, the Clair de Loon, the Sileaux, the Garage Mahal, the Glacial Sands, the Temple of Denture, the Golden Mukooda will lie across the basin like diamonds in a dish. Family-style casinos, with theme parks and sensational water rides on the rivers cascading over the north rim, plus high-rise hotels and time-share condominiums. Currently there are no building restrictions in Lake Superior; developers will be free to create high-rises in the shape of grain elevators, casinos shaped like casserole dishes, accordions, automatic washers. Celebrities will flock to the canyon. You’ll see guys on the Letterman show who, when Dave asks, “Where you going next month, pal?” will say, “I’ll be in Minnesota, Dave, playing four weeks at the Pokegama.” Tourism will jump 1,000%. Guys on the red-eye from L.A. to New York will look out and see a blaze of light off the left wing and ask the flight attendant, “What’s that?” And she’ll say, “Minnesota, of course.”

All of which actually reminds of Lebbeus Woods, and his vision of a drained Manhattan.

[Image: Lebbeus Woods, Lower Manhattan; view larger].

But perhaps such a willfully fictive reference overlooks the reality of the drought(s) now creeping up on the United States.

In a massive new article published this weekend in The New York Times, we’re given a long and rather alarming look at the lack of water in the American west, focusing on the decline of the Colorado River.

A catastrophic reduction in the flow of the Colorado River – which mostly consists of snowmelt from the Rocky Mountains – has always served as a kind of thought experiment for water engineers, a risk situation from the outer edge of their practical imaginations. Some 30 million people depend on that water. A greatly reduced river would wreak chaos in seven states: Colorado, Utah, Wyoming, New Mexico, Arizona, Nevada and California. An almost unfathomable legal morass might well result, with farmers suing the federal government; cities suing cities; states suing states; Indian nations suing state officials; and foreign nations (by treaty, Mexico has a small claim on the river) bringing international law to bear on the United States government.

And it will happen; this “unfathomable” situation will someday occur. The American West will run out of water.

[Image: Simon Norfolk, a photographer previously interviewed by BLDGBLOG, taken for The New York Times].

Or will it?

At one point in his genuinely brilliant book Cadillac Desert, Marc Reisner describes something called N.A.W.A.P.A.: the North American Water and Power Alliance. N.A.W.A.P.A. is nothing less than the gonzo hydrological fantasy project of a particular group of U.S. water engineers. N.A.W.A.P.A., Reisner tells us, would “solve at one stroke all the West’s problems with water” – but it would also take “a $6-trillion economy” to pay for it, and “it might require taking Canada by force.”

He quips that British Columbia “is to water what Russia is to land,” and so N.A.W.A.P.A., if realized, would tap those unexploited natural waterways and bring them down south to fill the cups of Uncle Sam. Canadians, we read, “have viewed all of this with a mixture of horror, amusement, and avarice” – but what exactly is “all of this”?

Reisner:

Visualize, then, a series of towering dams in the deep river canyons of British Columbia – dams that are 800, 1,500, even 1,700 feet high. Visualize reservoirs backing up behind them for hundreds of miles – reservoirs among which Lake Mead would be merely regulation-size. Visualize the flow of the Susitna River, the Copper, the Tanana, and the upper Yukon running in reverse, pushed through the Saint Elias Mountains by million-horsepower pumps, then dumped into nature’s second-largest natural reservoir, the Rocky Mountain Trench. Humbled only by the Great Rift Valley of Africa, the trench would serve as the continent’s hydrologic switching yard, storing 400 million acre-feet of water in a reservoir 500 miles long.

And that’s barely half the project!

The project would ultimately make “the Mojave Desert green,” we read, diverting Canada’s fresh water south to the faucets of greater Los Angeles – thus destroying almost every salmon fishery between Anchorage and Vancouver, and even “rais[ing] the level of all five [Great Lakes],” in the process.

After all, N.A.W.A.P.A. also means that the Great Lakes would be connected to the center of the North American continent by something called the Canadian–Great Lakes Waterway.

But N.A.W.A.P.A. is an old plan; it’s been gathering dust since the 1980s. No one now is seriously considering building it. It’s literally history.

But who knows – perhaps 2008 is the year N.A.W.A.P.A. makes a comeback. Or, perhaps, in January 2010, after another dry winter, Los Angeles voters will start to get thirsty. Perhaps some well-positioned Senators, in 2011, might even start making phonecalls north. Perhaps, in 2012, some recent graduates from water management programs at state-funded universities in Illinois or Utah might catch the itch of moral rebellion; they might then start redrawing their personal maps of the continent, going to bed at night with visions of massive dams in their heads, writing position papers for peer-reviewed hydrological engineering magazines.

Perhaps, in 2017, ten years from now, BLDGBLOG – if it’s still around – will even be reporting from the rims of these gigantic structures, thrown up overnight in the remote and untrafficked darkness of riverine western Canada. Long, perfectly calibrated concrete sluices and pumps will bring water thousands of miles south through redwood forests to the open basins of California’s reservoirs, and photographs of their incomprehensibly expensive and exactly poured geometry will elicit whistles of embarrassed awe from readers on the streets of Weehawken.

[Image: A fish-cleaning station in Las Vegas Bay, now abandoned by the West’s sinking waters; taken by Simon Norfolk for The New York Times].

Or perhaps it won’t be N.A.W.A.P.A. after all, but some titanic new project identical in all but name.

Will California wait for the coming drought to destroy it – or will the state take drastic measures?