Water it’s a giver and taker of life with it Marin land can be cultivated without it no life can be sustained because human history is replete with cycles of drought and flood. And we have sought both to conserve and to protect ourselves from this destructive an essential resource if you’re going to develop the resources of the nation you want to not let the river. Just flow into the sea without making some use of and we maximize our water use with Dan’s there are an estimated 900,000 dams. Worldwide most are small to medium-sized but 40,000 are over 50 feet high the most familiar dams the mega dams a select club of about 300 over 450 feet high are vital pieces of civilizations infrastructure in the nineteen thirties. We in the US realized that we could manage entire river basins not just one single damn at a time but dozens so we began developing river basins on the best scale it is scale that makes dams unique in the nineteen thirties dams in the United States became the largest constructions on earth.
And more than just huge feats of engineering they were seen as monuments as symbols of progress we’re using more material than has ever been used before sends the time of the pyramids and that’s something that you celebrate Grand Coulee Dam is the largest concrete structure in the United States other Giants include hoover dam and oral dam. But they are not new and because of environmental opposition and the lack of new sites in America’s waterways no dams this size will be built again in the United States we have essentially built as many as we need or is feasible to build dams do not create water there has to be water that can be manipulated through them to make them viable in America.
We have done but when the US was building big dams the developing world was taking note and with increasing regularity has followed suit Aswan Dam in Egypt a typo gap between Brazil and Paraguay. And finally the most ambitious hydroelectric dam in the world China’s three gorges dam which will exceed all other dams in size and power production like any hydroelectric facility three gorges dam will harness the power of water released from an elevated reservoir. To drive terminals and produce electricity this process is standard what’s unusual is how much electricity will produce the hydroelectric generators that are attached to this damn will generate 18 million kilowatts of power. And enormous amount of power the equivalent of 18 nuclear plants that’s enough electricity to light up shanghai China’s most populous city of almost 10 million people construction on the three gorges dam began in 1994 with the digging of a canal to reroute the Yangtze River earthen dams diverted the rivers flow around the construction site indicates of the Yangtze River. It’s a third largest river in the world needs to be completely diverted for a period of over 10 years while the dam is being built holding back the flood-prone Yangtze river has long been a top priority for the Chinese over the last two millennia the NC river has averaged a major flood once every 10 years. But in 1918 it wasn’t flood control but hydroelectricity the compelled China’s revolutionary leaders sun Yat-sen to promote a three gorges dam project. The country’s instability sideline the project until floods in the nineteen thirties and nineteen fifties killed hundreds of thousands of Chinese speaking Chinese officials to begin planning in earnest for a damn with a massive reservoir that could reduce flooding and produce electricity.
Because of the enormity of the project the damn remained in the planning stages until the people’s congress approved in 1992 plans called for 607 foot-high 1.4 mile long concrete gravity down with two powerhouses flanking essential spillway capable of passing 3.5 million cubic feet per second of the river’s water. Three gorges dam would contain 35 million cubic yards of concrete have to lay a 16-foot wide highway across the U.S. more than 10 times in 1997 with a diversion canal keeping the site dry workers began pouring concrete in a damn you start by creating what’s called this of 22 23 24 meters.
Where forms are put on the side to keep the concrete in a certain designated area then concrete’s poured in that area after pouring concrete for 10 years workers finished the main structure of the Damned 2006 an estimated 250,000 people have worked on this 22.5 billion-dollar project the costliest and perhaps largest construction project. In modern history many times big projects in developing countries are built by large American or European companies but the Chinese decided they wanted to build this mostly on their own with helping specialized areas from Western engineering companies with the day of structure complete the river was returned to its natural course and impounded in the 400 mile long reservoir behind the dam inundating 13 cities hundred and forty towns. And almost 1,400 village it’s the most dramatic chapter an ongoing relocation of an estimated 1.4 million people some experts predicted relocation costs will equal the cost of the dam itself adding to the controversy surrounding the day is the fact that it’s Reservoir will flood countless sites of historical and archaeological importance and inundate some of the area’s most fertile farmland like when the 26 fortune turbines are in place and generating electricity. They will supply 3% of China’s power needs the Chinese are still installing the generators full power production expected in 2009 one year ahead of schedule James maybe the construction giants of the 20th than now twenty-first centuries but their impact on civilization is ancient 5,000 years ago Mesopotamians develop this new technology. The damn to transform the desert into what would be known as the Fertile Crescent Mesopotamians used embankment downs earth and stone structures that hold back water with their mass to divert water into irrigation canals that fed their fields as damn technology spread throughout the region the dams themselves began to grow civilizations attempted to store water and pressure lines.
Just diverted diversion dams of the earliest but you don’t store a lot you’re still dependent upon the natural flow of the river as dams get taller you have the capacity to actually store the water to capture those spring floods those freshens and then use it later in the year but holding back a reservoir with just the weight of her trunks takes massive amounts of material the Romans engineered. A way to do more with less if you took a masonry wall and didn’t build it straight across and can but you built it with an arch that you could actually use the strength of the arch to help hold back the water but the arch is only as strong as the foundation into which is anchored arches were suited to narrow areas with solid rock foundations. The next innovation butter stands for more versatile they spread their load across the series of buttresses didn’t require massive amounts of fill material and could span wider areas despite these innovations the most common damn is still the earthen embankment am it’s the damn of choice in areas where the dam site is wide and there are large amounts of birth pill available an embankment down is the tallest in the United States. The 770 foot tall horrible game on the Feather River in northern California was built in nineteen sixties from clay and cobblestone recycled from an abandoned gold mine the clay is actually from a clay pit just couple miles away from here. It was brought up to this location via train system by 1963 workers have diverted the river with two tunnels and clear the site to bedrock next they began placing birth pill Orville damn is a gravity down that holds back water with its mass the core is composed of impermeable clay surrounded by a transition layer of course material. And cover in rock sand and gravel the weight of the structure is simply too great for the reservoir to push aside doing construction market wheel excavators dugout 3500 cubic yards of will power our workers transported to fail on conveyor belts to the train hopper. Where they loaded 40 train cars every 15 minutes three locomotives continually part of the 80 million cubic yards of material to the site where workers sorted it dumped into the dam and pack it down completed in seven years the Oracle damn supplies electricity drinking water and irrigation for central and southern California it’s reservoir in school we also provide flood control what the spillway provides for us is a safety device. If we need to release water out of the reservoir and get it around the dam into the Feather River when open 8 30 foot tall gates are capable of releasing 250 thousand cubic feet of water per second to the river below oracle the 19th largest dam in the world that are smoked dams in the US. Still engineers are retrofitting many smaller water storage and irrigation dams with hydropower finding ways to make more electricity from lesser dams in the 20th century dam-building displaced as many as 18 million people worldwide gains will return on water.
Rock Island dam on the Columbia River in the heart of Washington State a test of strength is taking place now it’s not dam vs. river these facilities withstood the water pressure for more than 70 years today deep within powerhouse one a decade-long modernization is about to begin and it starts the deadlift workers. Will have to ice the rotor a 270 1000 pound steel and copper assembly out of the top of the generating unit in each one of these 10 power units the rotor a rotating electro magnet spins inside a stationary stator which is packed with conductive copper wiring the rotors spinning electromagnetic carries in charge that causes electrons to move from atom to atom. And the stickers wiring producing the electron flow called electricity there’s a huge magnetic force about a million pounds that tries to draw these two magnets together so engineers work to design systems that can keep that rotor spinning it up to 90 RPM perfectly inside the stator. Has the equipment ages and bearings wear down the ruler begins to wobble and runs the risk of banging into the stator potentially destroying the machine so it must be pulled out and upgraded and operator positions to bridge cranes each capable of forcing be tons above the rotor this is delicate work. The rotor must be perfectly level as it’s coming out there’s about an eighth of an inch gap between the rotor and stator and as they’ve been lifting the rotor up because it’s not level it’s been coming in contact and hanging up on the edge of the stator finally the crane operator levels the huge roller enough to extracted cranes cart to load the length of the powerhouse. And gingerly sit down this unit was originally sold about 1953 and this is the first time it’s been out so it’s been in service for well over 50 years over the year’s insulation. And copper windings have worn down from exposure to heat vibration moisture and oil wear-and-tear decrease efficiency and can shut the generator down the motor will sit there for about four months while work crews removed the old copper laminations. Install new copper laminates improved purity and design Rock Island modernization will take 10 years and cost a hundred and eighty million dollars the project will extend the life of the powerhouse another 50 years after the upgrade the team’s power plant. Will produce ten percent more energy in the same amount of water this idea using dams to generate electricity began at the end of the 19th century with the advent of power lines that distributed electricity over distances private utilities began to build hydroelectric dams.
Even in remote areas the coming of hydroelectricity the coming of electric power systems and the eighteen eighties and the eighteen nineties really has a huge impact on why people want to begin to build dams in many different locations over the next hundred years states. And industries hungry for water and power began damming up virtually every major river in the united states in the nineteen thirties President Roosevelt in an effort to stimulate the depressed economy authorized the building of some of the country’s largest dam projects including the Shasta Bonneville. Grand Coulee dams decade by decade over the next 40 years the number of dams built with skyrocket 1400 dams built in the nineteen thirties with Spike to 8,000 built in the nineteen seventies. Many of the smaller dams were designed for water storage and irrigation not hydropower today the high cost of electricity his word interested in adding hydropower to be smaller dams they tend to be low head that means the difference in elevation from the upstream to the downstream of the dam is not so high.
These were not so economical to develop and to extract power from these dams which are often there for water storage or for navigation but today there is an interest in developing special designs for these low-head themes every project for voice Siemens a 140-year old German company. With a hydropower design facility and manufacturing plant in York Pennsylvania calls for custom design each project has a unique height of the Damned a unique amount of water versus the time of the year and so to match each of those variable conditions each plant is designed exactly for its condition the lower head dams on the Mississippi and Ohio rivers require a compact power plant. There isn’t much depth of these dams as a result axial-flow bulb turbines have been designed to be installed horizontally with the turban and generator all packed into one compact unit it basically has a central hub with the blades welded to the hub this whole runner is also made a hundred percent of stainless steel. This design will go into a powerhouse structure that has a lot of water flow but very small head and ends with her head in the 75 to 1,200 foot range engineers employ of Francis turbines these terms have fixed blades welded at the top and bottom to a crown. And a base princess turbines have greater structural rigidity to withstand increased water pressures at these higher head dams water actually comes in and makes contact directly with the surface of the bucket kind of like a prizefighter when he hits his opponent he wants to hit his opponent squarely opponent at a glancing blow.
He doesn’t transfer that energy the water operates on the same principle with these pockets the water conveyance system would involve the pen stone delivering water into a spiral case spiral case looks like a snail shell figure at the opening and in pollutes into a smaller diameter. As it wraps around machine this accelerates the water into the Francis runner which weighs 56 thousand pounds spins anywhere from 150 to 250 rpm and must be perfectly balanced actually believe slowly shaves it down we remove battle in designated areas on the runner so that the runners balance these massive turbines. Close to 10 million dollars to manufacture and as much as 1 million dollars just to ship to the dance up where they will be installed but energy from hydropower is extremely valuable because water power is flexible when the great advantages of hydro is you can turn it on and off relatively quickly if you have a big coal-fired steam plant. And you get that baby going you can’t turn that off very easily it might take days to cool down and it’s going to take days the heat back up with hydropower. You can actually turn those valves and in a matter of minutes go from nothing up to full power and that’s it’s great advantage but when these hydroelectric barriers block once free-flowing rivers how can ship sandfish get around the dams the power is responsible for about twenty percent of the world’s electricity games will return on modern marvels today the Columbia river is a vital shipping room. Flowing from the Canadian Rockies in British Columbia through Washington and Oregon dams have made this possible but only with some clever engineering the Columbia river is the United States largest gateway for the export of wheat about 8 10 million tons of cargo each year. Moves on the river its value somewhere between two and two and a half a billion dollars a year the dams on the Columbia River in Washington state like rock island a man Grand Coulee Dam don’t have locks and don’t allow should passage but just to the south Aight dams each with a lock transform the Columbia. And its tributaries the Snake River into a water highway spanning 465 miles from the Pacific Ocean to Lewis tonight at home.
Started coming out here in that tongue pushes for barges each one the length of a football field up the Columbia River towards the navigation lock at Mont Ville down. I’m open up the downstream gates being like for them to come in and at that point he’s almost dead stop otherwise he would just ran money in the wall on dry land you wouldn’t want to negotiate a parking spot this tight 650 feet is the largest toe you can put in and you might have you know a foot two feet to spare. On either and so it’s pretty tight it may be tight but this lock is the only way to lift boats up 60 feet and over the dam once it gets the gates closed I might have the gates pushing them together and then I start filling the water by operating to Tina valves now these tender bowels are valid to come open and let the water come in and run into the bottom fill up the locks the lock is a glorified bathtub. You have a large empty structure you have gates on either end there are no pumps involved this is all gravity but if it’s a bathtub it’s a massive one the locket Bonneville dam. Takes 10 minutes and needs a staggering 30 million gallons of water each time it builds once it gets in love I opened the upstream gates in morn green line and verbally telling the third to go you’ll see that agricultural and forestry products coming downstream going upstream fuel fertilizers.
The costs involved in that is so minimal compared to if you had to put them all on trains or if you had to put it all on trucks and you have to mourn for Bonneville down note or a five-year period during the great depression the damn deepen this rocky narrows making it possible for shipping Bonneville dam was a concrete gravity down that measures a hundred and eighty feet thick. At its base size-wise the two powerhouses are roughly a quarter of a mile long of peace same thing with a spillway we have a little less than 2 million cubic yards of concrete between the three structures. We generate about a little over of thousand megawatts of power the largest dam in the area of course is grand coulee they produce six times will be completed in 1941 grand coulee is the largest concrete dam in the United States. And typifies the multi-purpose role of the dams on the Columbia River the dam is used for power production flood control and irrigation if you think of the Pacific Northwest as the state of Washington Oregon Idaho and the western half of Montana about two-thirds of the power that is consumed in those four states is produced by hydropower region-wide. It is beneficial to people the dams on the Columbia River are damaging some of the rivers original inhabitants fish and in particular the region salmon populations salmon hatching the river migrate to the ocean to mature and return up the river to spawn.
The Dames presented huge obstacle to migration particularly to the small to mills or fingerlings heading out to sea at each damn you have a very high percentage of juveniles dying and its additive. So if you’re looking at ten to fifteen percent at each damn you’ve already lost a really large chunk of your potential run size before it even goes to the ocean the natural tendency is if you’re generating power is the water is in essence driving the fish down toward the turbines an effort to reduce losses the Army Corps of Engineers is installed a number of structures to protect fish including fish greens submerge traveling screens. They are large structures its slide down in the upstream side of the damage and then angle out and then have a motor on the fish come down catch the current and then there are directed into a bypass system the bypass system. Simply it’s a water falling around the structure rather than through the structure and then they’re deposited downstream during this process of moving the fish around the dams workers of the dams are able to collect about half of them which are then loaded into barges and shipped downriver directly to the ocean charging reduces fish mortality of the dams the trauma experienced. On route may simply lead to a later death in the ocean adults returning to spawn can use man-made fish ladders to pass over the dam at each of the dams there is a flow that comes through the ladders. That attracts the fish the fish then in essence are swimming through a small man-made stream rising two or three feet at a time moving up the hundred-foot rise and most of the dams on the Columbia snake system fish ladder is a path that allows you to go around the damn you get a fish waiting down at the bottom for a chance to get up.
And they’re using up their energy there and then they have 20 or 30 miles of slack water lake to swim through when I first got to this project in the early nineteen eighties hydropower was king if something interfering with hydropower. We didn’t do it now fish is king and if it interferes with fish we don’t do it that means shutting off a powerhouse that means showing off the power but why is bitch welfare become so important the main reason of course is the Endangered Species Act. That of course gives it a lot of cloud so with the runs getting dangerously low every fish is important that is tremendous amount of effort going in on the part of the various agencies to make sure that fish can get up and down past these dams but at the end of the day.
We’ve got a lot of runs that are upstream of the dams that are not doing well and there’s problems with them but the big dams are probably here to stay this little debate that hydropower is far cleaner and electricity derived from fossil fuels but when dams failed whole communities can be wiped out who’s looking after our aging inventory Daniels as many as 1 million adult salmon. And steelhead and fifty million fingerlings pass through Bonneville dam an average year dams will return on modern marvels flood it’s one of nature’s most potent destroyers of life and property in an area of frequent flooding one of the dams key selling points is its ability to restrain an onslaught of water. While we designed the damn to hold a certain amount of water we also design features into the damn that allow us to pass excess water around that large is the blood that we would have to handle through some sort of a spillway. In order to safely pass that water around the dam during a storm there are rare times when the dam itself is the cause of the fly at ten am on June 5th 1976 workers in southeastern Idaho try desperately to close an ever-widening fissure in the downstream. Face of the Teton down but the growing whole consume their bulldozers 1157 am the crystal the 305 footers and dam collapsed as its reservoir was being filled for the first time eighty billion gallons of water crashed down on the farming communities. Below the Dale directly downstream five communities Rexburg sugar city Wilfred Salem and Hibbert were swept away the wall of water ripped buildings from their foundations eighty percent of Rexburg was inundated and damaged the riverbank community of sugar city virtually disappeared the flood killed 11 people and 16,000 head of livestock and caused hundreds of millions of dollars in property damage loss of life. Would have been far greater and they’re not been time for an evacuation the Teton dam had been designed by the Bureau of Reclamation a division of the Department of the Interior. Now more than a century old the bureau overseas water development projects in the western United States and is built some 600 dams including the hoover and Grand Coulee Tetons collapse marks the loan failure among the bureau’s major towns. It led to an investigation that revealed three main causes of the catastrophe there were open fissures in the foundation those conditions could have had more attention given to them during the design of the Damned.
There was a very challenging for material the core material that was available locally was a silk material which is highly erosive and so it has to be very carefully protected and really the third contributing factor was not having some defensive measures that we now use on a regular basis. When we’re designing embankment dams namely being filters to keep the embankment materials where they belong the Teton incident had an impact on the federal government understanding that it had this tremendous infrastructure that needed to be cared for it needed to be paid attention to caring for aging Western dams is one of the main missions of the Bureau of Reclamation’s engineers. At their water resources research laboratory in Denver Colorado at this massive facility. They test ways to mitigate the host of factors that can cause a damn to give way water is incredibly heavy a single gallon weighs in at more than eight pounds dam’s director reservoir loads into their foundations. The water exerts 17,000 pounds of pressure per square foot long to the base of a damn the size of Teton down you have to take a look at the potential weaknesses in that foundation that would allow some sort of slippage. That would allow a piece or all of the dam to slide down stream and release the reservoir may find that there are storms possible that we’re never envisioned by the original designers which in that case would lead to an overtopping of the Damned and erosion of the downstream face overtopping excess water. Filling over the top of the dam is the most common cause of dam collapse spillways are really our primary feature for managing the release of water around the dam in a flood event particularly the spillway is basically a safe channel to carry the water around the down and get it back into the watercourse downstream at the Denver facility bureau engineers are testing a fuse plug an earthen gate designed to give way and allow water to pass in flood.
The water normally doesn’t go through this go away unless there’s a big flood and when there is a big flood it’s one of the individual embankment will wash away in a prescribed manner in order to open up that section of spill one of the challenges with spillways is to be able to quickly develop large capacities for discharge. But yet still be able to store water and one of the ways traditionally to do that has been gated spillways but to build a large gated spillway is extremely expensive whereas if we could replace those gates with an embankment that we could predict exactly.
How it would overtop how it would breach and know exactly how it would perform then we would have a much less expensive solution with ninety percent of its dams nearing the half-century mark the Bureau of Reclamation test the strength of the concrete dam every 10 or 15 years a good durable concrete. Will continue to strengthen as time goes on in some instances there are things like freezing and thawing or abrasion and we need to look at those items and monitor them overtime concrete continues to slowly hydrate for years absorbing water informing crystal lattices. That give it strength over a 50-year period the concrete in a damn may become as much as 250 percent stronger the smaller course we usually testing are 300,000 pounds machine in there today.
We have court from are over so water dam and this course was taken from our 15-year testing program right now it’s about 20 years old the point of the test is to test and compression until we find the ultimate compressive strength until it fails and that’s the maximum that we can get out of that concrete a compressive strength test will measure. How much pressure it takes to crush the score under just broke at seven thousand PSI which is slightly higher than we were expecting which shows us that it’s continuing to gain strength over time dam failures.
While catastrophic also unparalleled learning opportunities we had a significant incident with and we feel like we’ve learned some tremendous lessons and as a result of learning those lessons we have been very active in trying to share those lessons with others both throughout the United States. And throughout the world to try to further the cause of dam safety we can also learn a lot from nature’s quintessential dam builders their efforts are responsible for fostering some of the most vital habitats on earth bureau of reclamation dams provide irrigation water 440,000 farmers in the American West. We produce sixty percent of the nation’s vegetables Dan’s will return on modern marvels leave her gams can have a dramatic beneficial effect on their surroundings in many ways these rudimentary instructions built to create ponds that protect beavers from predators are ecologically far superior to their man-made counterparts a beaver dam. Has a positive impact on the local ecosystem almost immediately they trap sediment overtime then you’ve got vegetation that comes in starts filling and you’ve got a wetland you’ve got wetland plants emergent vegetation and that creates great habitat for a number of species big dams. Often simply submerge riparian habitats the lush life sustaining areas besides rivers beaver dams have the opposite effect some studies have shown something like seven to eight times as much right Marion habitat as a result of the Beaver Dam one light large dams which often store seasonal spikes in water volume beaver dams. Don’t block flows that are vital to the river psychology its habitat creation during those high flows when you actually have a river depositing organic matter creating this this variety of habitats it opens up new habitat for all kinds of species. To explore not just fish when you take out the variation in rivers flow the fish in the bugs they start to fade away they’re not getting the temperature cues and the volume cues that they need to complete their life cycles water held in a large dams reservoir stratifies altering the temperature and chemistry of the water in the river below the water and natural River is highly oxygenated. And it’s boiling around and when that river is dammed you’re basically changing this highly oxygen water into a slack water lake where the oxygen levels on top or bound to be very low and probably lower underneath which is fine for Lake fish but not for deliverance pieces some of these River fish like salmon are vital food sources for humans and water conditions of dams contribute to their declining numbers today.
Salmon populations are a mere six percent of their historic levels but there may be a technological solution to this oxygen-depleted water we’ve developed hollow turbine blades normal turbines are made of a big cast steel component and the solid but utilizing these hollow turbine blade designs were able to draw air into the turban in a cloud of small bubbles they pass oxygen from the air bubbles into the water. And therefore increase the dissolved oxygen in the in the water downstream of the dam that’s great for fishing after centuries of building downs some communities in the US.
Looking to remove them as an option particularly outdated ones communities are really embracing that we’re makes sense roughly 550 or so Dan’s have been have been removed the united states already over 200 since 1999 in the case of the Cascades damn in Yosemite National Park removal would mean returning a protected environment to a more wild state. I’m standing here on the banks of the Merced River here in Yosemite National Park were about three miles downstream for Yosemite valley and right at the former site of the Cascades diversion dam. This dam was built in the early nineteen hundreds to generate hydroelectric power for Yosemite Valley when the down was taken offline in 1985 and no longer produce power the dam and its structures were obsolete so we at the National Park Service decided to remove the damn completed in 1917. The 184 foot long timber creek dam was constructed of laws spike together to form careers that were filled with rocks chief with red wood boards and flanked by 30-foot high concrete abutments.
His rudimentary damn presented challenges to the planters of its removal there was a huge concern that we would remove the dam and there would be this huge washing of sediments downstream wouldn’t cause two hundred thousand dollars to build would cost 2.8 million dollars to demolish. After three years of planning a coup of 30 working with a bulldozer and an excavator remove the damaged just two months November and December of 2003 workers diverted the river to one side removed have two down and then rerouted the flow back and demolish the other side of the game engineers. Have tested sediment levels and found them to be low so sediment didn’t wash down and choked the river as they had feared workers use excess sediment to fill the hole with the damage been with the damn out-of-the-way environmental team said about restoring the habitat to that of a free flowing river we had a number of areas. To look at we had the channel itself that was going to be exposed we had a floodplain and then we had this app and each of them have their own unique issues the channel itself is going to drop 12 feet. That means that the water table is going to drop 12 feet the floodplains going to expand and that’s a great opportunity for us because that’s a very biologically rich area for plants and wildlife overall we planted about 3,000 ceilings here on the floodplains our wetlands species from the area.