HOOVER DAM FAST FACTS AND FIGURES Where is Hoover Dam? In Black Canyon on the Colorado River, about 30 miles southeast ofLas Vegas, Nevada. What were the excavation depths from the river's low-water surface to foundation rock? In the upstream cut offtrench, it was 139 feet. The remaining excavation depths average 110 to 130 feet. What are the geologic conditions at the dam site? The foundation and abutments are rock ofvolcanic origin geologically called "andesite breccia." The rock is hard and very durable. What construction work was necessary before operations started at the dam site? (I) Construction ofBoulder City to house both Government and contractor employees} . (2) construction of7 miles of22-foot wide, asphalt-surfaced highway from Boulder CIty to the dam SIte; . (3) construction of22.7 miles ofstandard-gauge railroad from the Union Pacific main line in Las Vegas to Boulder CIty and an additional 10 miles from Boulder City to the dam site; (4) construction ofa 222-mile-Iong power transmission line from San Bernardino, California, to the dam site to supply energy for construction. What were the principal divisions ofwork? . More than 5,500,000 cubic yards ofmaterial were excavated, and another 1,000,000 CUbIC yards ofearth and rock fill placed. By feature, this included: Excavation for the diversion tunnels, 1,500,000 cubic yards For the foundation ofthe dam, power plant, and cofferdams 1,760,000 cubic yards; For the spillways and inclined tunnels, 750,000 cubic yards For the valve houses and intake towers, 410,000 cubic yards Earth and rock fill for the cofferdams, 1,000,000 cubic yards. In addition, 410,000 linear feet ofgrout and drainage holes were drilled, and 422,000 cubic feet ofgrout were placed under pressure. When did construction begin? Construction on Hoover Dam began September 30, 1930. What were the quantities of principal materials used in the dam? The principal materials, all ofwhich were purchased by the government, were: Reinforcement steel, 45,000,000 pounds Gates and valves, 21,670,000 pounds Plate steel and outlet pipes, 88,000,000 pounds Pipe and fittings, 6,700,000 pounds or 840 miles Structural steel, 18,000,000 pounds Miscellaneous metal work, 5,300,000 pounds. How much steel and metal work was used to build the dam? There are 96,000,000 Ibs of steel and metalwork used by the dam - but none of it in the dam. What type ofdam is Hoover? Hoover Dam is a concrete arch-gravity type, in which the water load is carried by both gravity action and horizontal arch action. Why is the dam curved? The Hoover Dam is a curved gravity dam. Lake Mead pushes against the dam, creating compressive forces that travel along the great curved wall. The canyon walls push back, counteracting these forces. This action squeezes the concrete in the arch together, making the dam very rigid. This way, Lake Mead can't push it over. The Hoover Dam is so thick and heavy, it doesn't even need to be curved! It's heavy enough to resist the weight and thrust ofthe water pushing behind it, but designers thought people would feel safer with a curved design. When was the first concrete laid? The first concrete for the dam was placed on June 6, 1933 and approximately 160,000 cubic yards ofconcrete were placed in the dam per month until the dam was finished. Peak placements were 10,462 cubic yards in one day (including some concrete placed in the intake towers and powerplant), and slightly over 275,000 cubic yards in one month. The daily demand during construction ofthe dam was from 7,500 to 10,800 barrels. Reclamation had used only 5,862,000 barrels in its 27 years ofconstruction activity preceding June 30, 1932. How much concrete is in the dam?

Hoover Dam was the first single structure to contain more masonry than the Great Pyramid at Giza. There are more than 5,000,000 barrels, or 4,360,000 cubic yards ofconcrete in the dam, power plant and extra work places. Approximately 160,000 cubic yards ofconcrete were placed in the dam per month. Peak placements were 10,462 cubic yards in one day (including some concrete placed in the intake towers and power plant), and slightly over 275,000 cubic yards in one

1 month. This much concrete would build a monument 100 feet square and 2-1/2 miles high; This would rise higher than the Empire State Building (which is 1,250 feet); or would pave a standard highway 16 feet wide, from San Francisco to New York City or from Seattle, Washington, to Miami, Florida, or ifyou prefer - a four-foot-wide pavement around the Earth at the Equator. How much cement was required? More than 5 million barrels. The daily demand during construction ofthe dam was from 7,500 to 10,800 barrels. Reclamation had used only 5,862,000 barrels in its 27 years ofconstruction activity preceding June 30, 1932. How was the chemical heat caused by setting cement in the dam dissipated? By embedding more than 582 miles of I-inch steel pipe in the concrete and circulating ice water through it from a refrigeration plant that could produce 1,000 tons of ice in 24 hours. Cooling was completed in March 1935. What was an unusual feature of Hoover Dam's construction? The dam was built in blocks or vertical columns varying in size from about 60 feet square at the upstream face ofthe dam to about 25 feet square at the downstream face. Adjacent columns were locked together by a system of vertical keys on the radial joints and horizontal keys on the circumferential joints. Concrete placement in anyone block was limited to 5 feet in 72 hours. After the concrete was cooled, a cement and water mixture called grout was forced into the spaces created between the columns by the contraction ofthe cooled concrete to form a monolithic (one piece) structure. How long did it take to build the dam, power plant, and appurtenant works? Five years. The contractors were allowed 7 years from April 20, 1931, but concrete placement in the dam was completed May 29, 1935, and all features were completed by March 1, 1936. When was the last ofthe concrete poured in the dam? The last concrete was placed in the dam on May 29, 1935. How many men were employed during the dam's construction? A total of21,000 men worked on the Dam with an average of3,500 and a maximum of5,218 daily, which occurred in June 1934. The average monthly payroll was $500,000. How many generators does Hoover Dam have? Hoover Dam has 17 generators giving it the capacity to produce over 2,000 megawatts ofelectricity. How much power does Hoover Dam generate? The generators have a power generating capacity of 2.8 million kilowatts. How much water is needed to run the generators? During peak periods ofelectrical demands, enough water runs through the generators to fill 15 average-size swimming pools (20,000 gallons each) per second. How many people benefit from the water from the dam? Hoover Dam is part ofa system, which provides water to over 25 million people in the southwest United States. How tall is the dam? It is 726.4 feet or seven stories high, from foundation rock to the roadway on the crest ofthe dam. The towers and ornaments on the parapet rise 40 feet above the crest. That's almost 200 feet taller than the Washington Monument in Washington, D.e. How thick is the base ofthe dam? At its base, Hoover Dam is as thick (660 feet) as two footballs fields measured end to end. How thick is the concrete at the top? The dam is 45 feet thick at the top. How much does Hoover Dam weigh? More than 6,600,000 tons. What is the maximum water pressure at the base ofthe dam? 45,000 pounds per square foot. What is the reservoir Capacity? Total storage capacity is 9.2 trillion gallons or 1.24 trillion cubic feet or 30,500,000 acre feet ofthe Colorado River in its reservoir, or to put it another way the reservoir can store up 2 years 'average' water flow from the Colorado River. How much did it cost? The total cost to build the dam was $165 million. What is the name ofthe reservoir behind the dam? Lake Mead, the largest man made 'lake' in America. MORE FACTS ABOUT THE RESERVOIR. The surface area of Lake Mead is 146,000 acres. The maximum water surface elevation ofLake Mead is 1229 FT. The maximum depth of Lake Mead is 590 FT. The length ofLake Mead is 115 miles.

2 FLOOD! Why a Dam Was Needed.

In the distant past, the GulfofCalifornia extended 150 miles further inland from its present day shore. There it formed a bay 50 miles wide. Each year the river deposited over 140,000 acre-feet ofsilt at the rivers delta. This is enough to cover 214 square miles in 1 foot of soil. Eventually these accumulated deposits grew so thick the area was sealed offthe upper portion ofthe gulf. Cut offfrom the river, the water that remained formed a huge shallow lake. When the Colorado flooded, its waters would spill into this lake. Over time, flooding, local run-off and evaporation made this a salt-water lake. The area evolved into a geological anomaly. It became a huge 2000 square mile desert, the Colorado Desert and the lake was known as the Salton Sink. At its lowest point, it was 300 feet below sea level. In the early 1850's, an idea was conceived ofcutting a channel from the Colorado river to the Colorado Desert in California now known as Imperial Valley but it took until 1901, when a surveyor and engineer, Charles Rockwoo~ also saw the possibilities ofa canal to the area and approached an investor named George Chaffey who knew the value ofirrigation because he had made a fortune in the Los Angeles area planting Orange groves. Chaffey decided to underwrite the project and on May 14, 1901, the canal saw its ftrst water. A lot ofland was sold and people moved into the area. By 1904, the population ofImperial Valley grew to over 7,000. The agricultural production ofthe area went far beyond the most optimistic forecast. Unfortunately, sometimes when dreams come true, the dream might actually turn into a nightmare. In the spring of 1904 the huge volume ofsilt, which the Colorado carried with it found its way into the canal. By 1904 a 4-mile long section ofthe canal had become clogged with this silt. Efforts to keep the canal clear were in vain. In the fall and winter seasons the water flow ofthe Colorado subsided. The rivers flow into the canal completely subsided. A huge fortune in crops died due lack ofwater. In March 1905, the spring flooding season began and the Colorado River broke through and a small lake began to form in the Salton Sink. As more water accumulated, the Salton Sink became the Salton Sea covering about 150 square miles in 60 feet ofwater. By November 1905, matters got worse. By this time over150,000 cubic feet per second flowed through the canal.

The Colorado River was now flowing into the Imperial Valley instead ofthe GulfofCalifornia. Instead of huge tracts ofbountiful, irrigated croplands, this disaster promised to turn the area into a huge inland sea. Could things have gotten worse? Yes. It began as a small waterfall not far from where the river poured into the Salton Sea near Anza Borrego outside of San Diego. An erosion process know as a 'cutback' was beginning to make its effects known. The consequences ofthe cutback was likely to destroy huge sections ofsouthwest Arizona and southeast California. the sandy soil could not withstand the force ofthe water running over it. Trying to 'equalize' its descent into lower elevations, the river started to erode its way back to its highest point. The accumulated silt deposits weren't solid and there was no way to stop the process oferosion. In fact it was speeding up. The once tiny waterfall reached a height of 100 feet and was cutting through the desert at the rate of 1 mile a day. Ifthe cutback reached the intake, the falls would be 300 feet high and the river channel would be so deep that the Colorado River would never be able to return to the GulfofCalifornia. Some geologists, seeing that the same conditions existed throughout the whole area, predicted that the cutback could eventually carve a canyon 1 MILE deep and several hundred miles long! Sort ofanother Grand Canyon to go with the new inland sea. Under pressure from Theodore Roosevelt, E. Harriman, Robber Baron owner ofthe Southern Paciftc, made his money, engineers and facilities available to stop this disaster. It took 2 years and 3 million dollars to put the Colorado back in its original channel. On February10, 1907, the breach was ftnally closed. The nightmare had ftnally ended, for now. Then less than two years later the Colorado began flooding the valley again. It looked like it was going to be a repeat ofthe 1905-1907 episode. Finally, in 1910, the U.S. Congress, appropriated $1,000,000 to build a chain oflevees to give this problem some temporary relief from the flooding. This chain ofevents proved two things. It was obvious that something much more permanent was needed and that it was possible to harness this incredible river.

1 THE WATERS OF THE COLORADO.

A river has to start somewhere and the Colorado rises high up in the Colorado Rocky Mountains National Park at the Continental Divide, the point in American where the rivers decide whether to go east or west.

The Colorado goes west, travelling 1,450 miles and dropping 10,000 feet in its descent from the mountains to the sea, ending in the Gulf of California. It grows in size and strength as it's joined along the way by many tributaries.

The river does its greatest work during flood with the transportation ofrocks, suspended solids and dissolved materials. The amount carried by the river varies greatly. In Hood this mighty river has been gauged to have carried 27,600,000 tons ofdebris in one day although on an average day the amount is only 391,780 tons.

High water marks left by a flood that took place in July of 1884 computed to a maximum flow of 300,000 cubic feet per second. In 1927 the river flood averaged a massive 127,000 cubic feet per second and this was when California was flooded causing the loose of crops and money and fearing a worse flood like the one in 1884 would happen again, it was decided a dam was needed.

To put that into perspective, fthe approximate 400,000 average burden were loaded into dump trucks with a 5-ton capacity each, it would take 80,000 trucks going by at little more than a second apart for twenty-four hours to do the same amount ofwork the river does naturally each day.

Since the construction ofGlen Canyon Dam, which has slowed the river, the gouging effect has lessened and today the average is about 80,000 tons of material per day, or about 1/5th as much as when the river ran wild.

Studies show that the overall rate of 'carving' for the entire Colorado River Drainage area has been averaging about 6 Y2 inches for each 1,000 years. THE COLORADO RIVER AND THE COLORADO RIVER COMPACT

The Colorado River rises in the snow capped mountains ofnorth central Colorado and zigzags southwest for more than 1,400 miles before reaching the GulfofCalifornia.

The river and its tributaries - the Green, the Gunnison, the San Juan, the Virgin, the Little Colorado, and the Gila Rivers - are called the "Colorado River Basin." These rivers drain 242,000 square miles in the United States, or one-twelfth ofthe country's continental land area, and 2,000 square miles in Mexico. Seven western states and Mexico have beneficial interests in the Colorado River Basin and they are: Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming.

Each state is party to the Colorado River Compact entered into in Santa Fe, New Mexico, on November 24, 1922. This agreement divided the Colorado River Basin into the Upper Basin and the Lower Basin. The division point is Lees Ferry, a point in the main stem ofthe Colorado River about 30 river miles south ofthe Utah-Arizona boundary. The "Upper Basin" includes those parts ofthe States ofArizona, Colorado, New Mexico, Utah, and Wyoming within and from which waters naturally drain into the Colorado River system above Lees Ferry, and all parts ofthese States that are not part ofthe river's drainage system but may benefit from water diverted from the system above Lees Ferry.

The "Lower Basin" includes those parts ofthe States ofArizona, California, Nevada, New Mexico, and Utah within and from which waters naturally drain into the Colorado River system below Lees Ferry, and all parts ofthese States that are not part ofthe river's drainage system but may benefit from water diverted from the system below Lees Ferry. The Colorado River Compact apportions to each basin the exclusive, beneficial conswnptive use of 7,500,000 acre-feet ofwater per year from the Colorado River system in perpetuity. In addition, the Compact gives to the Lower Basin the right to increase its annual beneficial conswnptive use ofsuch water by 1,000,000 acre-feet.

The original Colorado River Compact did not apportion water to any State until October 11, 1948, when the Upper Basin States entered into the Upper Colorado River Basin Compact, which apportioned use ofthe Upper Basin waters among them. The compact now permits Arizona to use 50,000 acre-feet ofwater annually from the upper Colorado River system, and apportioned the remaining water to the Upper Basin States in the following percentages:

Colorado, 51.75 percent New Mexico, 11.25 percent Utah, 23 percent; and Wyoming, 14 percent. The Lower Basin States ofArizona, California, and Nevada were not able to reach agreement. In 1952, Arizona filed suit in the United States Supreme Court to October 1962, the Court ruled that ofthe first 7,500,000 acre-feet ofmain stem water in the Lower Basin, California is entitled to 4,400,000 acre-feet, Arizona 2,800,000 acre-feet, and Nevada, 300,000 acre-feet.

The United States has contracted with the States ofArizona and Nevada and with various agencies in Arizona and California for the delivery ofColorado River water. These contracts make delivery ofthe water contingent upon its availability for use in the respective States under the Colorado River Compact and the Boulder Canyon Project Act.

The United States and Mexico entered into a treaty on February 3, 1944, which guarantees Mexico 1,500,000 acre-feet ofColorado River water annually. This entitlement is subject to increase or decrease under certain circumstances provided for in the treaty.

1 THE COMPANIES WHO BUILT THE DAM

The dam was under the direct supervision ofthe Washington and Denver offices ofthe U.S. Government's Bureau of Reclamation; actual designs ofall its features were made in the Denver office. It was built by a group of western contractors, calling themselves the Six Companies.

When Washington announced it had the job for somebody, a sudden low scribbling was heard in the land. This was the sound ofestimating. Most of it died very quickly, as contractors realized the job was too huge even to bid on. But in San Francisco, Salt Lake City, Boise, and Portland, telephones jangled and very quickly the hard heads of Bechtel & Kaiser and MacDonald & Kahn (San Francisco), Morrison-Knudson Co. (Boise), Utah Construction Co. (Salt Lake City), and Portland's J.F. Shea and the Pacific Bridge Co. were put together. They set up a joint corporation capitalized for $8,000,000, called it the Six Companies, scribbled, estimated, and bid $48,890,995, bonded the contract for $5,000,000 in cash. They got the job.

For their $48,890,995 the Six Companies had to foot all construction bills - for dynamite, for trucks, for digging mud and dumping mud, for bosses' salaries, and for labor's wage. The Six companies did not pay for construction raw material- for the 5,500,000 barrels of cement consumed, or the 55,000 tons ofsteel plates and castings, or the turbines and generators in the power plant, or any ofthe pennanent operating machinery ofthe dam.

It is not feasible to detail a month's or even a year's statement ofthe Six Companies, since their expenses varied enonnously. They were out ofpocket $3,500,000 for preliminary work before they received a government penny. Until halfthe work was done they received only ninety cents on the dollar. The holdback is around $2,000,000, which they received at the end - like an ice-cream cone for being good. It suffices perhaps to say that during the first five months of 1933 the government paid an average monthly bill from the Six Companies of $1 ,513,000. out ofthis the corporation paid items such as a half­ million a month payroll, $48,000 for gas and oil, $40,000 for electricity.

At one time when the roads were roughest, they were spending $500 a day for truck and automobile tires. When the last bills were paid and the turbines began to turn, the Six companies turned a profit estimated at $7,000,000 and upward for all their work.

This profit, which must be understood, is the insurance premium the U.S. pays for efficiency. Ifthe contractors spent all their money, botched the job, and went broke, the government might have to finish the dam to the tune ofa great many millions. The U.S. was willing to pay a good profit for a good dam built rapidly.

One ofthe few complaints ofthe men on the job is that the bosses were "highballing" ­ labor slang for forcing work to the limit. Their contract started April 20, 1931. they "highballed" the job to a point seventeen months ahead of schedule. This speed cost the 1 Six Companies money in many operations - money, which was more than saved by finishing the darn an estimated year and a half before its appointed birthday, April 20 1938. a government inspector was required, who reported the contents of every batch of cement, the blast of every dynamite barrage, the loads on the cableways, and the depth of every hole. He even went down the canyon wall on ropes to outline the rock to be moved. He had to report on the tons ofrock chipped off by high scalers. Over 150 men were paid government money to stick their noses into the contractor's business. Not until they were satisfied that the work conformed in the minutest detail to rigid V.S. specifications did the Six Companies get Washington's check for the preceding month's payroll and expenses. The man in charge of the inspectors was Walker Young, (General Superintendent, Six Companies). He worked with Frank Crowe, (V.S. Construction Engineer in charge). Such a system should build a good darn but it could also cause some friction but the friction factor at Boulder was nearly non-existent and the reason is in the history and makeup of the two men in charge of building the darn.

Frank Crowe and Walker Young had two reasons why they were not bitter enemies. One was that the job was too big for petty human friction. Young's inspectors and Crowe's foremen knew this as well as their bosses. They knew that friction, which slows work, quietly rubs somebody out of a job. The second reason was the mutual respect of the two men. Crowe spent years in the V.S. Reclamation Service, which Young now represented. He knew Young's duties and responsibility as well as Young did. "I'd go to hell for him," Crowe was quoted as saying.

NOTE; Frank Crowe got $25,000 a year plus bonuses. Young got $6,375 in bonus and up to this job this government work rated no bonus. Regardless of salary, Walker Rollo Young was the undisputed boss at Boulder Darn.

2 WHERE THE MEN WHO BUILT THE DAM CAME FROM

State Number of Men State Number of Men Alabama 243 Nebraska 157 Arizona 643 Nevada 5522 Arkansas 191 New Jersey 104 California 5055 New Mexico 109 Connecticut 467 New York 221 Colorado 467 New Hampshire 14 Delaware 1 North Carolina 120 Florida 66 Ohio 260 Georgia 115 Oklahoma 581 Idaho 599 Oregon 273 Illinois 487 Pennsylvania 238 Indiana 159 Rhode Island 8 Iowa 181 South Carolina 29 Kansas 327 South Dakota 58 Kentucky 103 Tennessee 121 Louisiana 85 Texas 604 Maine 18 Utah 1165 Maryland 66 Virginia 44 Massachusetts 114 Vermont 6 Missouri 548 Washington 642 Michigan 251 West Virginia 73 Minnesota 208 Wisconsin 171 Mississippi 50 Wyoming 161 Montana 340 Foreign workers 116

Total = over 21,000 LIVING AND WORKING CONDITIONS AT HOOVER DAM: RAGTOWN The real story behind Hoover Dam is the thousands who built it and the families that endured the living hell to bring it all to realty. In particular those that died from the harsh conditions or on the job.

Construction ofHoover Dam didn't begin until April of 1931, but men and their families began drifting into Las Vegas (30 miles from the dam site) in early 1929 after the Stock Market Crash of 1929 and the Great Depression. Vegas was a small desert outpost and not prepared for the thousands of"new residents", unemployed desperate people who poured in for a limited number ofHoover Dam construction jobs. Many came with all their possessions, wives, children and little or no money and because ofthat they had no choice but to live in squalid, tightly compacted tent cities. Dam construction was months away and there was no guarantee ofemployment, but many had nowhere else to go and those that did had no money to get there. Many citizens of Las Vegas provided food, care and clothing for the migrants who managed to survive very tough conditions. Prompted by the Depression and mounting stress on future dam workers and the town of Las Vegas, the government pushed the construction to begin six months early. Although the federal government had begun planning for housing and human welfare infrastructure, they used the excuse that the quickened construction schedule left no time for barracks or house building. Then the hiring began and the work commenced. Some who had transportation stayed in Las Vegas to make the daily commute through 30 miles ofthe dusty and bumpy Boulder road but since most people equated being close to the dam site with the success ofgetting a job, most decided to live near the job site. The infamous community of"Ragtown" on the floor ofBlack Canyon next to the Colorado River was born. The makeshift shantytown consisted oftents, cardboard boxes, tin scraps and anything else that could serve as shelter against the scalding heat ofsummer and freezing nights of winter. Ragtown first swelled to 1,400 people looking for employment and then, as construction reached its peak, the population ballooned to 5,000 men, women and children. Even under the best ofconditions dam building is tough, exhausting work. Those working on the construction ofHoover Dam had to contend with other factors that made their work much more risky and dangerous. One was the searing, relentless heat as the temperature at the work site would routinely soar to above 120 degrees during the summer and plummet to well below freezing in the winter. An added pressure felt by the workers was the insistence ofsupervisors and managers to finish the job in record time. Millions ofdollars were at stake. Six Companies, the outfit building the dam, had agreed to a rigid government deadline--two and a half years to divert the river or face steep fines for every day they ran late. In the rush to meet their deadline, Six Companies often sacrificed the men's safety for speed. Working seven days a week, dam workers were exposed to all manner ofdangers: carbon monoxide poisoning, dehydration, heat prostration, and electrocution from carelessly placed electrical lines. To top it off, workers knew they had very little leverage to lobby for changes. With a quarter ofthe nation's work force idle, the workers at Hoover Dam knew they were expendable. Frank Anderson, a professional organizer for the radicallabor union, the Industrial Workers ofthe World (IWW), had been dispatched to Las Vegas to recruit members and stir up demands for better working conditions and higher pay. Workers regarded Anderson and the IWW with suspicion and fear because they knew any affiliation with any labor group, and that one in particular, would result in their having no job to complain about. Meanwhile, Six Companies, along with officials in Las Vegas and elements within the Reclamation Service, made concerted efforts to discredit and drive out the IWW. Frank Anderson was jailed on trumped up vagrancy charges. Workers reached a breakpoint during July and August of 1931 as life in Ragtown became devastating. With average July temperatures of 116 degrees and approaching 130 degrees on the floor of Black Canyon combined with swirling dust and no natural shade, over 25 men, women and children died in that first June-July period ofheat conditions. PTO

1 Then on August 7, Six Companies reassigned a number ofdiversion tunnel workers to lower paying jobs. Within hours, the entire work force went out on strike. Six Companies contended that only 30 muckers, unskilled laborers who loaded broken rocks into trucks, would be affected by the pay reduction. Workers decided that it was time not just to protest the pay cut but to list their grievances and issue demands. Among them: that clean water and flush toilets be provided, that ice water be readily available to workers, and that Six Companies obey all mining laws issued by the States ofNevada and Arizona. Significantly, the striking mine workers also voted to disassociate themselves from the IWW. Upon reviewing the workers' demands, job supervisor Frank Crowe echoed the feelings of his bosses in rejecting every one ofthem. The strikers made a last- ditch appeal to the U.S. Secretary ofLabor, William Doak, to intervene on their behalf. He refused. Knowing they were beaten, and worried they might not get their jobs back, the strikers voted to return to the dam site but only once Six Companies pledged its pay cut would be the last. Additionally they agreed efforts had to be made to improve work conditions and additional lighting and water was made available, and construction ofliving quarters in Boulder City was sped up. Life didn't change quickly for the people ofRagtown or for the workers. The federal government already had plans to build a dam workers town on federal land above and close by Black Canyon where Hoover Dam would stand. Because ofthe publicity generated by the strike, and the reaction ofthe general public, they pushed forward to achieve workers relief with barracks, housing, stores and general public welfare with churches and schools for the children. That town which became Boulder City, Nevada was completed in 1932. While they waited for a decent place to live in, a man by the name ofMurl Emery and his family provided compassionate relief when they opened a store in Ragtown for dam workers and families with food and supplies trucked from Las Vegas. With low hourly labor rates of50 cents an hour, Murl Emery permitted Ragtown residents to pay what they could afford. Credit was issued on the honor system and only one person ever failed to pay his debt - and that was because the customer died. With no help from the government or the contracted dam building firm, it was Murl Emery and family that provided some relief in the form offood and tangible needs. Although clouded with sediment, the ever flowing water from the Colorado River was sufficient for bathing. The women would drape a wet cloth over baby cradles to cool them. Fresh milk was no option and canned food was the only way to avoid spoilage. Times were tough and harsh on everyone, but especially on the black workers and their families. In the 1930s racism and segregation was rampant and the attitude ofthe Six Companies, Inc. was no exception. Many blacks came to Las Vegas and Black Canyon with hopes offmding dam building jobs and most were turned away. The federal government mandated that Six Companies, Inc. hire more black workers but they made only a token effort by hiring less than 30 blacks and they were given only the most demeaning jobs such as debris cleanup and other labor functions undesired by white workers. To make the difficulties facing the black workers worse they weren't allowed to live in Ragtown and had to commute daily from Las Vegas. Six Companies, Inc. also had employment practices that expressly restricted the hiring of "chinamen" and in spite ofan abundance ofNative Americans in the region just a few were ever hired. All ofthem were given the most dangerous ofjobs, which was "high scaling" dangling precariously on the canyon walls while clearing obstructions for the eventual joining ofdam ends to those canyon cliffs. However, they were paid a higher hourly rate versus generallaborers and were permitted to live in Ragtown, which eventually became Boulder City. Boulder City thrives today as a quiet town that overlooks Lake Mead and rides high above Hoover Dam. Many ofthe "Ragtown Children" and their children are now actively involved in the community that provides some ofthe most rewarding quality oflife in America.

2 WORKERS' STRIKE AT HOOVER DAM

Even under the best of conditions, dam building was tough, dangerous work. Those working on the construction of Hoover Dam had to contend with other factors that made their work more risky and trying. One was the searing, relentless heat. The temperature at the work site would routinely soar to above 120 degrees during the summer and plummet to well below freezing in the winter. An added pressure felt by the workers was the insistence ofsupervisors and managers to finish the job in record time. Millions ofdollars were at stake. Six Companies, the outfit building the dam, had agreed to a rigid government deadline--two and a half years to divert the river or face steep fmes for every day they ran late. In the rush to meet their deadline, Six Companies often sacrificed safety for speed. Working seven days a week, dam workers were exposed to all manner ofdangers: carbon monoxide poisoning, dehydration, heat prostration, and electrocution from carelessly placed electrical lines. To top it off, workers knew they had little leverage to lobby for changes. With a quarter ofthe nation's work force idle, the workers at Hoover Dam knew they were expendable. Frank Anderson, a professional organizer for the radicallabor union, the Industrial Workers ofthe World (IWW), had been dispatched to Las Vegas to recruit members and stir up demands for better working conditions and higher pay. Workers regarded Anderson and the IWW with suspicion and contempt. They knew any affiliation with a labor group could result in their having no job to complain about. Meanwhile, Six Companies, along with officials in Las Vegas and elements within the Reclamation Service, made concerted efforts to discredit and drive out the IWW. Frank Anderson was jailed on trumped up vagrancy charges. Workers reached a breakpoint during the summer of 1931, however. On August 7, Six Companies reassigned a number of diversion tunnel workers to lower paying jobs. Within hours, the entire work force went out on strike. Six Companies contended that only 30 muckers, unskilled laborers who loaded broken rocks into trucks, would be affected by the pay reduction. Workers decided that the time was ripe, not just to protest the pay cut, but to list their grievances and issue demands. Among them: that clean water and flush toilets be provided, that ice water be readily available to workers, and that Six Companies obey all mining laws issued by the States ofNevada and Arizona. Significantly, the striking mine workers also voted to disassociate themselves from the IWW. Upon reviewing the workers' demands, job supervisor Frank Crowe echoed the feelings ofhis bosses in rejecting every one ofthem. The strikers made a last­ ditch appeal to the D.S. Secretary ofLabor, William Doak, to intervene on their behalf. He refused. Knowing they were beaten, and worried they might not get their jobs back, the strikers voted to return to the dam site. Six Companies stood by its pay cut, but pledged it would be the last. Additionally, efforts were made to improve work conditions as additional lighting and water was made available, and construction of living quarters in Boulder City was sped up.

1 FATALITIES AT HOOVER DAM

The most asked question is: How many people died building the dam? There are several stories that I found that can be used depending on who is included as having died on the project.

One popular number is 112. With this number you get 110 plus the story ofthe first and last men to die on the project. It goes something like this. On December 20, 1922, lG. Tiemey, a Bureau ofReclamation employee engaged in a geological survey from a barge in the Colorado River fell in the river and drowned. Thirteen years to the day, on December 20, 1935, Patrick W. Tiemey, a Bureau or Reclamation employee and son ofJ.G. Tierney, fell from one ofthe intake towers.

This version has a couple ofproblems. First, the dam was built from 1931 to 1935, so J.G. Tiemey was not really involved in the "construction" ofthe dam. He was doing a geological survey to decide where the dam would be built, but he was not the first person doing the survey to die. On May 15, 1922, Harold Connelly, also fell off of a barge and drowned. So, why isn't he considered the first person to die on the project. Well, for one thing it would not make as good a story as the Tierney family. To get around this it is pointed out that Connelly died while surveying a canyon upstream from the present site ofthe dam, while both Tiemey's died in the canyon where the dam was eventually built.

Another common number is 96. There were 96 industrial fatalities during the construction ofthe dam. Industrial fatalities includes deaths from drowning, blasting, falling rocks or slides, falls from the canyon walls, struck by heavy equipment, truck accidents, etc. Industrial fatalities do not include deaths from the heat, pneumonia, heart trouble, etc.

The second most asked question is: How many ofthose who died are buried in the concrete? The answer is - none! There are no bodies buried in the concrete. The dam was built in interlocking blocks, built on top ofeach other as they went. Each block was five feet high. The smallest blocks were about 25 by 25 feet, and the largest blocks were about 25 by 60 feet. Concrete was delivered to the blocks in buckets, eight cubic yards at a time. After each bucket was delivered five or six men would tromp around on the inside ofthe block, packing down the concrete and making sure there were no air holes. These men were called "Puddlers". Each time a bucket was emptied into the largest blocks the level ofthe concrete increased by two to three inches. How can you lose a body in two to three inches of concrete? Of course the smaller blocks did fill up faster. Each time a bucket was emptied into the smaller blocks the level was raised about six inches. Even with six inches the nose and the toes would have stuck out, and the puddlers would have seen them. There are no bodies buried in Hoover Dam. In fact they call that a Dam Lie! WAGES

NOTE: The amounts shown are per hour ofwork, and the men worked eight-hour days. If you see an entry like .825 it means that person earned eighty two and a half cents per hour. Job Wage Job Wage Shifters .875 to 1.00 Miners .70 Chuck Tenders .625 Nippers .625 Muckers .50 Muck Machine operator 1.00 Muck Machine helper .50 Brakeman .50 Dumpmen .50 Drill doctor .70 Jackhammer men .625 Compressor operator .625 Motormen .625 Greasemen .50 Electricians .75 Electrician's helper .50 Pipefitter .625 to .75 Pipefitter helper .50 Pipemen comp. line .625 Blacksmith .625 to .75 Blacksmith helper .50 to .625 Machinist.75 Mechanic .75 Mechanic's helper .50 Sawfilers .75 Tool sharpener .75 Welder .625 to .75 Welder's helper .50 to .625 Riggers .625 to .75 Truck drivers (Ford) .50 to .625 Truck drivers (Intl.) .625 Truck drivers (Moreland) .75 Cat operator .75 Shovel operator 1.25 Oilers .625 Carpenters .70 to .75 Carpenter's helpers .50 Carpenters, rough .625 Cement finisher .625 Laborers .50 Boat operators .625 Steel sharpeners .75 Powder men .70 Pumpmen .625 to .70 Muck Machine doctor 1.00 American Crane operator .75

The lowest wage was 50 cents an hour, and the highest was $1.25. The average for all ofthe workers at the dam was about 62.5 cents an hour.

How does that compare to the rest ofthe country at that time? It was pretty good. Fifty cents an hour, eight hours per day for a year works out to $1460.00. The average 62.5 cents an hour works out to an annual income of$1825.00, and the highest wage, $1.25, works out to $3650.00 per year.

It still does not seem like much until you compare it to what other people were making at that time. Below is a table showing some comparisons on an annual basis. Job Wage Job Wage Steel Worker $422.87 Coal Miner $723.00 Hired Farm Hand $216.00 Waitress $520.00 Bus Driver $1,373.00 Civil Service Employee $1,284.00 Engineer $2,520.00 Doctor $3,382.00 Lawyer $4,218.00 United States Congressman $8,663.00

1 HIGH SCALERS Millions of years ofweather eroded the canyon walls. Water froze in cracks and crevices, splitting the rock. Before construction could begin on the dam, this loose rock had to be removed. Special men were chosen for the job, men called "high-scalers." Their job was to climb down the canyon walls on ropes. Here they worked with jackhammers and dynamite to strip away the loose rock. The men who did much ofthis work came from many backgrounds. Some were former sailors, some circus acrobats, most were American Indians who were told that ifthey wanted to work this was all that was available for them. All of them had to be agile men, unafraid to swing out over empty space on slender ropes. It was hard and dangerous work, perhaps the most physically demanding work on the entire project. Laden with tools and water bags, the men would descend the canyon walls. Jackhammer drills were lowered to them, and powder holes were drilled into the rock. The jackhammers weighed 44 lbs and had to be maneuvered into position by hand. Once the holes had been drilled into the rock, they were loaded with dynamite. After the shot, broken rocks sometimes had to be levered free using crowbars. Moving about on the cliffs was difficult and hazardous. Live air hoses, electrical lines, bundles ofdrill steel covered the cliffwalls. The scalers had to carefully pick their way through the resulting maze. The danger from falling rocks and dropped tools was extreme. The most common cause of death during the building ofthe dam was being hit by falling objects. The men began making improvised hard hats for themselves by coating cloth hats with coal tar. These "hard-boiled hats" were extremely effective. Several men were hit by falling rocks so hard that their jaws were broken by the impact, yet they didn't receive skull fractures. Because of these "hard-boiled hats," men survived accidents, which would otherwise have killed them. After the strike The Six Companies. Inc. contracted for commercially made hard hats and issued them to every man on the project. The use of hard hats was encouraged, and deaths from falling objects were reduced. The risk and high visibility ofthe job lent it a certain status, which appealed to some types ofmen. When the foremen weren't looking, they would swing out from the cliffs and perform stunts for the workers below. Contests were held to see who could swing out the farthest, the highest, or who could perform the best stunts. It wasn't all done for fun and games, though. For several weeks, scaler Louis "The Human Pendulum" Fagan transported a crew of shifters around a projecting boulder on the Arizona side. The man to be transferred would wrap his legs around Fagan's waist, grasp the rope, and with a mighty leap, they would sail out into the air and swing around the boulder. Fagan then returned for the next man in the crew. This acrobatic transportation was accomplished again at the end ofeach day to bring the men back to the other side of the boulder until the job was finished. Perhaps the most famous feat any ofthe high scalers ever performed was a daring midair rescue. Burl R. Rutledge, a Bureau of Reclamation engineer, fell from the canyon rim. Twenty-five feet below, high scaler Oliver Cowan heard Rutledge slip. Without a moment's hesitation, he swung himself out and seized Rutledge's leg. A few seconds later, high scaler Amold Parks swung over and pinned Rutledge's body to the canyon wall. The scalers held Rutledge until a line was dropped and secured around him and the shaken engineer was pulled, unharmed, to safety. DOG ON A CATWALK

On the canyon wall, just across from the escalator leading to the new Tour Center at Hoover Dam, is a plaque dedicated to a dog. Puzzled visitors often ask the guides and guards why the plaque is there. The answers to these questions help keep alive the saga ofthe fIrst and only Hoover Dam mascot. Details ofthe mascot's birth are a bit obscure, but Morgan Sweeney and Blackie Hardy agreed that he was born under the Six Companies No. 4 barracks, and they should know. Mr. Sweeney was with the commissary section supplying the food to the workers during construction and Mr. Hardy drove one of the huge transports that hauled the workers from Boulder City to the dam site. After construction of the dam, Mr. Hardy worked as a guide at Hoover Dam. The dog's rough black puppy fur did not smooth out entirely as he matured and he never quite grew up to his outsized paws, but perhaps these odd characteristics helped to endear him to the workers. He was hardly weaned when Mr. Hardy picked him up one morning and tossed him on the transport. When the dog fIrst saw the dam, he knew that was where he belonged. It became his life. The only life he ever knew or wanted. Every morning he boarded a transport and put in a full days work along with the other workers. He inspected everything daily. As the dam rose higher and higher he had to ride the skips, a type of open-air elevator, to cover the ground. When he wanted to board a skip, he barked, and the operators always stopped for him. The mascot would hop aboard and bark again at the level where he wished to get off. Trainers will tell you that one ofthe most difficult tricks to teach an animal is to get them to walk on any swaying, unstable surface, but Hoover Dam's mascot raced happily back and forth across the swinging catwalks slung across the canyon seven hundred feet above the Colorado River. The Hoover Dam mascot was not a one-man dog. He had no master. He belonged to the dam and everyone connected with it, and they all belonged to him! If he decided to work overtime at his favorite job ofchasing ring-tailed cats that infested the tunnels, he hitched a ride back to town in the fIrst Bureau ofReclamation or Six Companies car, truck or transport that happened along. No one ever remembers him accepting a ride from anyone not connected with the dam. How he could differentiate between dam workers and casual visitors no one could fIgure out, but it is a known fact that he did. Everyone wanted to feed the dog, and being a dog, he found it hard to refuse. He became quite sick. The worried workers then decided that the dog needed supervised feeding. Arrangements were made with the commissary for the dog to be fed and word was passed to all workers not to offer him any more food. The commissary packed a lunch for him every day and he soon learned to carry it in his mouth when he boarded the transport. At the construction site, he placed the sack alongside the workers' lunch pails

1 and went about his business. When the whistle blew, the dog raced for his sack and sat patiently until someone opened it for him. Workers leaving the job frequently stopped at the commissary and left a few dollars with the manager - "Just to see that the dog gets fed well." These contributions soon grew to a respectable sum and a bank account was opened for the Hoover Dam mascot. The money paid for his food, dog license, and some sleeping baskets (which he never used) and silver collars that he detested. Sometimes these collars were stolen by souvenir hunting tourists. The fund also paid for advertisements in the Boulder City and Las Vegas papers, such as this one.

I Love Candy But It Makes Me Sick. It Is Also Bad For My Coat. Please Don't Feed Me Any More. Your Friend, The Hoover Dam Mascot

One evening, ChiefRanger Peterson was notified that a group of workers was beating a man to death. ChiefPeterson dashed to the scene and broke it up. When he learned the cause ofthe riot, the Chief told the victim he would like to see the job finished but it was his duty to stop it. The Chiefescorted the bloody and bruised man to the town limits and told him never to come back. The man had made the near-fatal mistake of kicking the Hoover Dam mascot. After the dam was completed, the dog took it upon himself to see that the rule "NO DOGS ALLOWED LOOSE ON DAM" was rigidly enforced. His ironclad insistence on the letter ofthe law caused some embarrassment to members ofthe Guide Force, but these skilled diplomats always managed to convince indignant pooch owners that the mascot actually owned the dam. The Bureau of Reclamation merely built and operated it for him. On a day when the blazing desert sun, combined with a blast furnace wind, pushed the thermometer over the 120-degree mark, the dog found a spot ofshade under a truck. The driver never noticed the sleeping dog when he started up and drove off. News ofthe fatal accident was phoned to town and it was the quietest afternoon Boulder City ever experienced. Later, rough, tough, hard rock men wept openly and unashamed as they slammed their ear-shattering jackhammers into the hard rock cliff, carving out the grave, which was to be the Hoover Dam mascot's tomb. So, in death as in life, the Hoover Dam mascot looks upon the dam he loved for as long as it will stand and when the wind howls around the towers ofthe dam, the old-timers smile knowingly. It isn't wind. It's the dog baying at the ring-tailed cats.

2 BUILDING THE DIVERSION TUNNELS

Before actual Hoover Dam construction could begin, the Colorado River had to be temporarily diverted around the dam construction site. It was a daunting, difficult project. At that time there were no roads into Black Canyon, so initially, dam workers and equipment had to be brought by boat. Over time, roads were built and catwalks were stretched across the river. Summer temperatures often reached 140 degrees in the canyon and the winter months brought freezing.

Carving the diversion tunnels was a slow, tedious process that exposed dam workers to immense danger from blasting, falling rocks and diesel gas fumes spewed by the trucks that carried out blasting debris. Compressed air was circulated into the tunnels through large pipes. However, despite the difficulties, through intramural competition ofthe crew shifts, the tunnels would be completed almost a year early.

But in the beginning, it took countless men to make even an inch penetration into the canyon walls. To quicken the process, a drilling "Jumbo Truck" was retrofitted with layers ofplatforms that were backed into the face ofcanyon walls. This enabled 20-30 men to simultaneously drill holes for blasting powder. Eight ofthese jumbo trucks were implemented and lights were installed permitting around the clock progression.

The blasting holes were filled with dynamite with a ton ofdynamite used for about every 14 feet of tunnel. After explosion, dump trucks hauled the rock debris downriver and placed in spoil dumps along the canyon for later use. The diversion tunnels were lined with intricate forms for concrete lining. Initially a base ofconcrete was poured. The sidewalls were then poured into moveable sections ofsteel form and rail directed cranes were used to place the concrete. Pneumatic concrete guns were used to fill the overhead forms resulting in a total concrete lining that was 3 feet thick..

Previously, a barrier across the inlets to the Arizona side tunnels was installed. When the Arizona tunnels were ready to accept water flow, the barrier was breached with explosives and the flow began through those tunnels. Earthen and rock debris were trucked in and dumped from a trestle to block the Colorado River channel which forced the flow ofwater into the diversion tunnels. Eventually, cofferdams were built at the entrance to the other tunnels so they all worked as a team to divert water around the Hoover Dam construction site.

The core heart ofHoover Dam construction was now ready to begin.

1 THE COFFERDAMS

To isolate the construction site, and protect it from flooding, two cofferdams were constructed. Construction ofthe upper cofferdam began in September, 1932, even though the river had not yet been diverted. A temporary horseshoe-shaped dike protected the cofferdam on the Nevada side ofthe river. After the Arizona tunnels were completed, and the river diverted, the work was completed much faster.

The upper cofferdam was located approximately 600 feet down river from the inlet portals of the diversion tunnels. Before the cofferdam could be constructed, 250,000 cubic yards ofriver silt had to be removed to provide a firm foundation.

When completed, the upper cofferdam stood 98 feet high, and reached about 30 feet above the top ofthe diversion tunnels. The dam was 450 feet long, 750 feet thick at the base and contained 516,000 cubic yards ofearth and 157,000 cubic yards ofrock. The upstream face was protected by a 6" thick concrete paving laid over 3' ofrock blanket. The downstream face was covered by a thick rock fill.

This cofferdam was designed so that ifthe diversion tunnels were discharging water at 200,000 cubic feet per second, the water would still be 13 feet below the crest ofthe cofferdam (200,000 cubic feet per second was the largest flow ofwater ever recorded through Black Canyon).

Work on the lower cofferdam was delayed while the high-scaling ofthe canyon walls above the sites ofthe power plant and outlet works was completed.

The lower cofferdam was built ofa compressed earth fill. It was 66 feet tall, 350 feet long and 550 feet thick at the base. The cofferdam contained Approximately 230,000 cubic yards of earth, and another 63,000 cubic yards ofrock. A thick rock fill covered the downstream side ofthe cofferdam.

Because the lower cofferdam was made ofa soft earth fill, there was concern that during floods, back washing from the outlet portals would damage the cofferdam.

To lessen the force ofthe water, approximately 350 feet down river from the lower cofferdam a rock barrier was built. This barrier was 54 feet high, 375 feet long and 200 feet thick at the base. It contained approximately 98,000 cubic feet ofrock.

The cofferdams, rock barrier, and diversion tunnels were all completed before the spring floods of 1933. The engineers watched nervously to see ifthe dams would hold. They did, and the diversion tunnels easily handled the flood waters.

The work ofactually building Hoover Dam could begin. THE CONCRETE Concrete consists of four ingredients-sand and crushed rock aggregate, water and Portland cement. These must be mixed in the proper proportions to yield strong concrete. Aggregate is perhaps the most important ofthe materials in the concrete because it makes up as much as three quarters ofthe Dam's mass. The aggregate must be clean and free ofclays, salts and organic matter. A source ofaggregate near the Dam was needed so that it would not have to be transported too far.

Bureau ofReclamation prospecting parties searched the desert around Black Canyon for months, looking for a good supply of aggregate. Eventually, an alluvial lens just over six miles upstream on the Arizona side ofthe river was chosen as the source. Here, floodwaters had been depositing stones for millions ofyears. Some ofthe rounded stones were as much as 12" in diameter and had been washed down from as far away as the Grand Canyon. The deposit covered more than 100 acres thirty to thirty-five feet deep.

A dragline was used to excavate the aggregate and load it into rail cars. The cars hauled the aggregate to a screening and washing plant on the Nevada side of the river at Hemenway Wash.

At the screening plant, four screening towers separated the aggregate into different sizes; fine, intermediate and coarse gravels, and cobbles 3-9" in diameter. Anything over 9" was run through a crusher and screened again. The separated gravel and cobbles were carried to the mixing plants by train.

The initial concrete required for the dam was mixed in a river-level mixing plant, which was located approximately 3/4 of a mile upriver from the dam site. This plant provided the concrete for the linings in the diversion tunnels and for the lower levels ofthe dam. It went into operation on March 3, 1932. The concrete was loaded into buckets which were transported to the site initially by truck. Eventually, the concrete buckets were transported by electric trains. For the first year ofoperation, nearly all ofthe concrete produced at this plant, almost 400,000 cu. Yds. went into the linings ofthe diversion tunnels. In the tunnels, the concrete buckets were moved by a gantry crane, which ran on rails from one end ofthe tunnel to the other.

The first concrete was placed into the dam on June 6, 1933. The concrete was placed in the dam using 4 and 8 cu .yds. bottom dump buckets. These buckets were lifted from the cars and lowered into place by overhead cable ways. There were a total ofnine ofthese cable ways used to place the concrete. Five ofthe cable ways were connected to moveable towers, which allowed them to be repositioned to work on different parts ofthe dam when necessary.

As the dam rose in height, a new concrete mixing plant was constructed on the canyon rim. Completely automated, the hi-mix plant measured ingredients, mixed and dispensed the concrete. It was capable ofproducing 24 cu. yd. ofconcrete every three and a halfminutes. The hi-mix plant was used to produce all ofthe concrete placed in the dam above the 992 foot level.

1 One ofthe problems was that in order to produce the strength concrete required, a very dry mix had to be used. There was very little time available to move the concrete from the mixing plant to the dam. Iftoo much time was taken, the concrete would take its initial set still in the dump buckets and would have to be chipped out by hand. For this reason, the men who operated the cranes which moved the buckets into place were some ofthe highest paid workmen on the project, earning $1.25 per hour. As each bucket was dumped, seven puddlers used shovels and rubber-booted feet to distribute the concrete throughout the form and pneumatic vibrators to ensure there were no voids.

As the dam began to rise to fill the canyon, it grew in fits and starts. Rather than being a single block ofconcrete, the dam was built as a series ofindividual columns. Trapezoidal in shape, the columns rose in five foot lifts.

The reason that the dam was built in this fashion was to allow the tremendous heat produced by the curing concrete to dissipate. Bureau ofReclamation engineers calculated that ifthe dam were built in a single continuous pour, the concrete would have gotten so hot that it would have taken 125 years for the concrete to cool to ambient temperatures. The resulting stresses would have caused the dam to crack and crumble away.

It was not enough to place small quantities of concrete in individual columns. Each form also contained cooling coils of 1" thin-walled steel pipe. When the concrete was first poured, riVer' water was circulated through these pipes. Once the concrete had received a first initial cooling, chilled water from a refrigeration plant on the lower cofferdam was circulated through the coils to finish the cooling. As each block was cooled, the pipes ofthe cooling coils were cut offand pressure grouted at 300 pounds per square inch by pneumatic grout guns.

To prevent the hairline fissures between the blocks from weakening the dam, the upstream an downstream faces ofeach block were formed with vertical interlocking grooves; the faces turned toward the canyon walls with horizontal vertical grooves. When the concrete had cooled, grout was forced into these joints, bonding the entire structure into a monolithic whole.

Hoover Dam was the first man-made structure to exceed the masonry mass ofthe Great Pyramid of Giza. The dam contains enough concrete to pave a strip 16 feet wide and 8 inches thick from San Francisco to New York City. More than 5 million barrels ofPortland cement and 4.5 million cubic yards ofaggregate went into the dam. Ifall of the materials used in the dam were loaded onto a single train, as the engine entered the switch yards in Boulder City, the caboose would just be leaving Kansas City, MO. Ifthe heat produced by the curing concrete could have been concentrated in a baking oven, it would have been sufficient to bake 500,000 loaves ofbread per day for three years. NAMING HOOVER DAM By the time it was officially dedicated on September 30, 1935, the colossal dam project on the Southern Nevada portion ofthe Colorado river had been called by several different names. In the exploratory stage, the project was referred to as the Boulder Canyon Project. Boulder Canyon, was replaced by Black Canyon, when Black Canyon was discovered to be a more suitable spot to place the dam. Having started its legislative life under the moniker ofBoulder Canyon, the dam project simply adopted the title Boulder Dam. All of that changed, temporarily at least, on September 17, 1930, when Secretary of the Interior Ray Lyman Wilbur journeyed to the Nevada desert to drive the spike marking the project's official start. Sweating profusely through his inappropriate wool suit, Wilbur announced, "I have the honor and privilege ofgiving a name to this new structure. In Black Canyon, under the Boulder Canyon Project Act, it shall be called the Hoover Dam. " Hoover was Wilbur's boss and the current president ofthe United States, Herbert Hoover. He was also, in Wilbur's estimation, "the great engineer whose vision and persistence, first as chairman ofthe Colorado River Commission in 1922, and on so many other occasions since, has done so much to make [the Hoover Dam] possible. " Wilbur's unofficial dedication was greeted with much derision, seeing whereas the country at the moment was suffering through a crippling depression for which many citizens placed blame squarely on Hoover's shoulders. The naming of a momentous public works project in his honor was seen by many as bald-faced public relations and little more. Even after Wilbur's proclamation, the dam was referred to in the press by both names, but it was called Hoover in all official documents and congressional appropriations bills. When Hoover lost the White House to Franklin Roosevelt in 1932, Wilbur lost his position as Interior Secretary to Harold Ickes. Shortly thereafter, Hoover also lost his dam. On May 8, 1933, Ickes decided that the dam in Black Canyon would revert to being called Boulder Dam. Ickes defended his decision by stating, "The men who pioneered this project knew it by this name." He failed to mention that Herbert Hoover was one ofthose men. Few doubted that Ickes' action was politically motivated and personally charged; he didn't like Hoover and rejected the notion ofhis name being attached to any project that would be regarded with honor. Ickes carried his snubbing ofHoover all the way to the day ofthe dam's dedication. "This great engineering achievement," Ickes said, "should not carry the name of any living man but, on the contrary, should be baptized with a designation as bold and characteristic and imagination stirring as the dam itself" Ickes failed to mention that dam sites named after Presidents Woodrow Wilson, Theodore Roosevelt, and Calvin Coolidge already existed in Alabama and Arizona. For his part, Hoover, in his memoirs, maintained that having the dam stripped ofhis name was unimportant. Twelve years later, Hoover was vindicated when House Resolution 140 was introduced and passed by the 80th Congress. The resolution read, in part, "as President, Herbert Hoover took an active part in settling the engineering problems and location ofthe dam in Black Canyon..." and noted that "the construction contracts were signed under his administration, and when he left office construction had been pushed to a point where it was more than a year ahead of schedule. " On April 30, 1947, President Harry S Truman signed the resolution and restored the name Hoover Dam to the structure.

1 POWER DEVELOPMENT The power plant is located in a V-shape structure at the base ofthe dam. Each power plant wing is 650 feet long, 150 feet above normal tailrace water surface, and 299 feet (nearly 20 stories) above the power plant foundation. In all of the galleries of the plant there are 10 acres of floor space. The capacity of the Hoover Power plant is massive to say the least. There are 17 main turbines in Hoover Power plant. The original turbines were all replaced through an uprating program between 1986 and 1993. With a rated capacity of 2,991,000 horsepower, and two station-service units rated at 3,500 horsepower each, for a plant total of 2,998,000 horsepower, the plant has a nameplate capacity of 2,074,000 kilowatts. This includes the two station-service units, which are rated at 2,400 kilowatts each. One of the questions asked most often is, 'what is horsepower in terms of falling water?' The short answer is - One cubic foot ofwater falling 8.81 feet per second equals one horsepower at 100 percent efficiency. The water reaches the turbines through four pressure penstocks, two on each side of the river. Shutoff gates control water delivery to the units. The turbines operate under a Maximum head (vertical distance water travels), of 590 feet; minimum, 420 feet; average, 510 to 530 feet. Power installations in the plant was completed in 1961 with the uprating completed in 1993. There are fifteen 187,000 horsepower, one 100,000 horsepower, and one 86,000 horsepower Francis-type vertical hydraulic turbines. There are thirteen 130,000 kilowatt, two 127,000 kilowatt, one 61,500 kilowatt, and one 68,500 kilowatt generators. All these machines are operated at 60 cycles. There are also two 2,400 kilowatt station-service units driven by Pelton water wheels. These provide electrical energy for lights and for operating cranes, pumps, motors, compressors, and other electrical equipment within the dam and power plant. The power plant machinery was transported from the canyon rim to the power plant by an electrically operated cableway of 150 tons rated capacity, with a 1,200-foot span across the canyon, lowered all heavy and bulky equipment. The cableway is still used when necessary.

The average annual net of energy generation for The Hoover Power plant for operating years 1947 through 2000 is about 4 billion kilowatt-hours. The maximum annual net generation at Hoover Power plant was 10,348,020,500 kilowatt-hours in 1984, while the minimum annual net generation since 1940 was 2,648,224,700 kilowatt-hours in 1956. A kilowatt-hour is a unit ofwork or energy equal to that done by one kilowatt of power acting for one hour. A kilowatt is 1,000 watts or 1.34 horsepower. The power plant is operated and maintained by the Bureau ofReclamation and the principal contractors for energy are the States ofArizona and Nevada; the City of Los Angeles; the Southern California Edison Co.; the Metropolitan Water District of Southern California; the California cities ofGlendale, Burbank, Pasadena, Riverside, Azusa, Anaheim, Banning, Colton, and Vernon; and the city of Boulder City, Nevada. PTO

1 Hoover Dam firm energy generated is allocated as follows: Arizona - 18.9527 percent Nevada - 23.3706 Metropolitan Water District of Southern California - 28.5393 percent Burbank - 0.5876 percent Glendale -1.5874 percent counties in Pasadena - 1.3629 percent California Los Angeles - 15.4229 percent

Southern California Edison Co. - 5.5377 percent Azusa - .1104percent Anaheim - 1.1487 percent Banning - 0.0442 percent counties in Colton -0.0884 percent California Riverside - 0.8615 percent Vernon - 0.6185 percent Boulder City, Nevada - 1.7672 percent

The income from the sale of energy used is used to pay all operation and maintenance expenses and to repay the major part ofthe construction cost ofthe dam and power plant, at interest not exceeding 3 percent. The cost of construction completed and in service by 1937 was finally repaid on May 31, 1987. All other costs, except those for flood control, will be repaid within 50 years ofthe date ofinstallation or as established by Congress. Repayment ofthe $25 million construction cost allocated to flood control is currently deferred. In addition, Arizona and Nevada each receive $300,000 annually in lieu oftaxes.

2 SPILLWAYS

Many people who take the tour here at Hoover Dam want to know when they will get to see the water go over the top ofthe dam. Well, the water has never gone over the top ofthe dam and probably never will. We don't want the water to go over the top ofthe dam for a couple ofreasons. First, the power house is located at the foot ofthe dam. The power house contains 17 large generators, each producing enough electricity to service about 100,000 people. All that water would be bad for the electrical generators (water and electricity don't play well together). Second, there are about 18,200 vehicles a day going across the top ofthe dam, and we don't want those vehicles to get swept away. The road across the top ofthe dam is a federal highway, and it is the shortest way to get from Las Vegas to points east.

Water will probably never go over the top ofthe dam due to the spillways. The spillways workjust like the overflow hole in your bathtub or sink at home (if you don't remember seeing that hole, go look for it right now). Ifthe water ever gets up that high, it will go in the hole and down the drain, not over the top and onto the bathroom floor (unless, you have children and they plugged up the hole). The spillways are located 27 feet below the top ofthe dam, one on each side ofthe dam. Any water getting up that high will go into the spillways then into tunnels 50 feet in diameter, and 600 feet long which are inclined at a steep angle and connect to two ofthe original diversion tunnels. Each spillway can handle 200,000 cubic feet per second (cfs) ofwater. The flow at Niagara Falls is about 200,000 cfs, so there is the potential for two Niagara Falls here.

Each spillway has four steel drum gates, each 100 feet long and 16 feet high. These gates can't stop the water going into the spillway, but they do allow an additional 16 feet ofwater to be stored in the reservoir Each gate weighs approximately 5,000,000 pounds. Automatic control with optional manual operation is provided for raising and lowering the gates. When in raised position a gate may be held continuously in that position by the pressure ofwater against its bottom, until the water surface ofthe reservoir rises above a fixed point, when by action ofa float the gate is automatically lowered. As the flood peak decreases, the gate can be operated manually so as to gradually empty the flood control portion ofthe reservoir without creation offlood conditions down stream. The spillways have been used twice. The first time, in 1941, was a test ofthe system. The second time, in 1983, was for a flood.

The Arizona spillway was placed in operation for the first time on August 6, 1941, soon after the reservoir level had reached a maximum elevation of 1220.44. The drum gates were raised for several hours on August 14, 1941, and a hurried inspection revealed that the tunnel lining was intact, and the inclined portion showed little or no signs oferosion at that time. Operations were then continued without interruption until the reservoir level had been lowered to elevation 1205.60 on December 1, 1942. The average discharge flow through the Arizona spillway during this period was approximately 13,500 cfs with a maximum flow of38,000 cfs on October 28, 1941, when one ofthe drum gates dropped without warning.

That much water falling 600 feet down a very steep tunnel caused erosion ofthe tunnel lining The eroded area was approximately 115 feet long and 30 feet wide, with a maximum depth ofapproximately 45 feet.

The original volume ofthe cavity was 1069.6 cubic yards. Repair work was started almost immediately, but because it was believed that ordinary concrete was not suitable it was decided to utilize the Prepack and Intrusion process of concrete repair developed by the Dur-ite Company ofChicago, IL. After repair, the tunnel was polished smooth to help prevent future erosion.

During 1983, record flows into Lake Mead were recorded. The record surface elevation was recorded on July 24, with more than two feet ofwater spilling over the raised spillway gates ofNevada and Arizona. The record flows through the spillway tunnels again caused erosion in the concrete base, which had to be repaired. High water was responsible for wide spread damage throughout the project.

1 JET FLOW GATE TESTING BRINGS A CROWD

"Jet flow gate testing" doesn't sound like an event that would bring reporters, cameramen, and news helicopters out to Hoover Dam, located a fair distance from their regular news beats in downtown Las Vegas. But in June, 1998, as a torrent ofwater sent whitecaps rippling down the Colorado, the tests fascinated observers and garnered newspaper and television coverage from several local media outlets. Twelve obsolete needle valves were replaced with new jet flow gates in the outlet works at Hoover Dam to meet criteria that require the dam to release 73,000 cubic feet per second without using the spillways. Previously, the outlet works had a release capacity of about 50,000 cubic feet per second (one cubic foot is 7.48 gallons). The jet flow gates are devices that are designed to operate under high pressure. They include a steel plate that can be raised or lowered to either prevent or allow water to be discharged from a structure, much like the fancet in your sink controls the flow ofwater. The eight gates in the lower valve houses are 68 inches in diameter and each is capable ofdischarging approximately 3,800 cubic feet per second (28,424 gallons per second) at the present lake elevation. When a gate is closed, the force ofthe water behind it is 248 pounds per square inch, or 900,736 pounds per gate! The four gates in the upper valve houses are 90 inches in diameter and each is capable of discharging approximately 5,400 cubic feet per second (40,000 gallons per second). The test was performed to obtain water release data from the new jet flow gates and ensure there was no loss ofefficiency to the generators during their operation. The speed ofthe water coming out ofeach ofthe lower gates at maximum flow was calculated at 120 miles per hour! At maximum opening, each gate discharged about 28,424 gallons ofwater per second. That's enough water to fill the average backyard swimming pool in less than one second! The upper gates are situated 180 feet above the river. Water from the gates shoots across the canyon to strike the wall on the other side. The water exits the gates at 120 feet per second, or 83 miles an hour. When all four upper gates are in operation they could fill an Olympic size swimming pool, 500,000 gallons, in three and a halfseconds.

1 LAKE MEAD

Maximum length 120 miles Surface area 247 square miles Maximum depth 489 feet Water volume Maximum: 26,134,000 acre feet Current: 13,518,000 acre feet Shore length 550 miles (the shore length is not a well-defined measure due to increasing droughts.) Surface elevation Maximum: 1,229 feet

Lake Mead is the largest reservoir in the United States in maximum water capacity. It is located on the Colorado River about 30 mi southeast ofLas Vegas, Nevada, in the states ofNevada and Arizona. Formed by the Hoover Dam, it extends 112 miles behind the dam, with the potential to hold approximately 26,134,000 acre feet ofwater when full. However, the lake has not reached this capacity in more than a decade because ofdrought.

The lake was named after Elwood Mead (January 16, 1858 - January 26, 1936), who was the commissioner ofthe U.S. Bureau ofReclamation from 1924 to 1936 during the planning and construction of the 'Boulder Canyon Project' that created the dam and lake.

Lake Mead was established as the Boulder Dam Recreation Area in 1936, administrated by the National Park Service. It was then changed to the Lake Mead National Recreation Area in 1964, this time including Lake Mohave and the Shivwits Plateau under its jurisdiction. Both lakes and the surrounding area offer year-round recreation options. The accumulated water from Hoover Dam forced the evacuation of several communities, most notably St. Thomas, Nevada, whose last resident left the town in 1938. The ruins of St. Thomas are sometimes visible when the water level in Lake Mead drops below normal.

At lower water levels, a high-water mark or "bathtub ring" is visible in photos that show the shoreline of Lake Mead. The bathtub ring is white because ofthe deposition ofminerals on previously submerged surfaces.

The lake is divided into several bodies. The large body closest to the Hoover Dam is Boulder Basin. The narrow channel, which was once known as Boulder Canyon and is now known as The Narrows and connects Boulder Basin to Virgin Basin to the east. The Virgin River and Muddy River empty into the Overton Arm, which is connected to the northern part ofthe Virgin Basin. The next basin to the east is Temple Basin, and following that is Gregg Basin, which is connected to the Temple Basin by the Virgin Canyon. When the lake levels are high enough, a section ofthe lake farther upstream from the Gregg Basin is flooded, which includes Grand Wash Bay and the Pearce Ferry Bay and launch ramp. In addition, there are two tiny basins, the Muddy River Inlet and the Virgin River Basin, that are flooded when the lake is high enough where these two rivers flow into the lake. As ofnow, however, these basins remain dry.

Jagged mountain ranges surround the lake, offering somewhat ofa startling but beautiful backdrop, especially at sunset. There are two mountain ranges within view ofthe Boulder Basin, the River Mountains, oriented north-west to south-east and the Muddy Mountains, oriented west to north-east. From the Virgin Basin, you can view the majestic Bonelli Peak towards the east.

Las Vegas Bay is the terminus for the Las Vegas Wash which is the sole outflow from the Las Vegas Valley.

Lake Mead's water level has fallen below the drought level (1125 feet above sea level) three times. From 1953 to 1956, the water level fell from 1,200 to 1,085 feet. From 1963 to 1965, the water level fell

1 from 1,205 to 1,090 feet. Since 2000 through 2008, the water level has dropped from 1215 to 1095. In 2009 the water level rose slightly due to cool winter temperatures and rainfall.

In June 2010, the lake was at 39 percent ofits capacity, and on Nov. 30,2010 it reached 1,081.94 ft, setting a new record monthly low. From mid May 2011 to September 22,2011, Lake Mead's water elevation increased from 1095.5 feet to 1115.24 feet, and the rivers feeding it were running at 128.06% of the average flow rate for September 22.

Lake Mead draws a majority of its water from snow melt in the Colorado, Wyoming, and Utah Rocky Mountains. Since 2000 the water level has been dropping at a fairly steady rate due to less than average snowfall. As a result, marinas and boat launch ramps have either needed to be moved to another part ofthe lake or have closed down completely.

The Las Vegas Bay Marina and the Lake Mead Marinas were relocated a few years ago to Hemenway Harbor. Overton Marina has been closed due to low levels in the northern part ofthe Overton Arm, Government Wash, Las Vegas Bay, and Pearce Ferry boat launch ramps have also been closed. The marinas that remain open include Las Vegas Boat Harbor and Lake Mead Marina all sharing Hemenway Harbor/Horsepower Cove, Callville Bay Marina, Echo Bay Marina, and Temple Bar Marina, along with the Boulder Launch Area (former location ofthe Lake Mead Marina) and the South Cove launch ramp.

Changing rainfall patterns, climate variability, high levels ofevaporation, reduced snow melt runoff, and current water use patterns are putting pressure on water management resources at Lake Mead as the population depending on it for water and the Hoover Dam for electricity continues to grow. A 2008 paper in Water Resources Research states that at current usage allocation and projected climate trends, there is a 50% chance that live storage in lakes Mead and Powell will be gone by 2021, and that the reservoir could drop below minimum power pool elevation of 1,050 feet as early as 2017. Lake volume is now at the mercy ofa cascade offorces that include the fact that it is very likely impossible that the prevailing climate pattern of profound drought will or can change to precipitation surcharge in a time frame shorter than that in which the lake level will fall below the dead storage level of the downstream diversion and hydro-power intake tunnels. However, water levels in the lake rose by more than 30 ft in 2011 due to a rainy winter and increased snowfall in the Rocky Mountains.

Lake Mead offers many types ofrecreation to locals and visitors. Boating is the most popular. Additional activities include fishing, water skiing, swimming and sunbathing. There are five marinas on the lake: Forever Resorts at Callville Bay, Echo Bay, and Temple Bar Marina; and Las Vegas Boat Harbor along with Lake Mead Marina in Hemenway Harbor which are family owned and operated. The area also has many coves with rocky cliffs and sandy beaches. There are several small to medium-sized islands in the lake area depending on the water level. In addition, the Alan Bible Visitor Center has a small cactus garden ofplants native to the Mojave Desert.

In 1948, while testing a prototype missile guidance system known as "Suntracker" a Boeing B-29 Superfortress crashed into Lake Mead and is still at the bottom of the lake as are the wreckages ofat least two smaller airplanes.

2 THE COLORADO RIVER BRIDGE

The Hoover Dam Bypass Project is a 3.5-mile corridor beginning in Clark County, Nevada and crossing the Colorado River approximately 1,500 feet downstream of the Hoover Dam, then terminating in Mohave County, Arizona. The increasing congestion caused by the switchbacks leading to the Hoover Dam site and the restrictions at the dam crossing have led to the development of the Hoover Bypass Project. The highway, which crosses over Hoover Dam, US 93, has been designated a North American Free Trade Agreement route because of all the cargo transported along this highway is one ofthe prime routes across the United states. Now completed, this signature bridge spans Black Canyon which connects Arizona and Nevada approach highways nearly 900-feet above the Colorado River. The Colorado River Bridge is the central portion of the Hoover Dam Bypass Project. Construction on the nearly 2,000 foot long bridge began in late January 2005 and the completion ofthe entire Hoover Dam Bypass Project was in June 2010. The "Bypass" is a wonderful idea because it addresses several issues with one solution. The increased traffic is a very practical reason for the bridge. The trucks carrying goods between the states won't need to go over Hoover Dam highway making the trip faster and easier. The security issues are obvious. There will no longer be a need to drive through Hoover Dam if you are trying to go north or south on US 93 and trucks will no longer need to be checked before crossing the Dam anymore except in extreme and unusual emergencies. The traffic congestion due mainly to the trucks trying to cross the Dam will also be greatly reduced making it more convenient for visitors. The current number oftrucks and cars crossing Hoover Dam is over 14,000, double from 15 years ago. The bridge will itself has become an attraction. The two mega projects together side by side are a classic contrast in styles from two different eras. The bridge has become the place to see Hoover Dam from and Hoover Dam will become the place to see the bridge. The final results ofthis project are interesting and unforeseen. The slow and difficult road which crosses over Hoover Dam is a testament to the difficulty in building in this area in the first place. By making Mojave County Arizona more accessible to those living in Las Vegas, they will travel there and through there more often is part ofArizona is already seeing an increased and a faster pace in development. Towns are expected to grow where none exist and around Las Vegas there are already two new, growing towns, Laughlin and Primm. Property values have to started rising in Northern Arizona because ofthe increased flow oftraffic through and increasingly, to, this area. One ofthe unforeseen benefits ofHoover Dam, the huge popularity ofLake Mead, was probably never considered. The fact that there are nine to ten million visitors a year to Lake Mead would probably seem unbelievable even to Herbert Hoover back in the 1920's. The simple elegance and hugeness ofthis bridge lets it fit into, rather than clash with its surroundings. 1