The Hoover Dam
The story of the Hoover Dam, with
which Jim Farndale was associated
In 1932,
still a finish carpenter, Jim
Farndale had become Business Agent for the Carpenter's Union. It was in
this year that he first became involved in the Boulder Dam project. By 1935 Jim
had proved himself to be an efficient administrator through his work with the
Carpenter's Union and the Boulder Dam Project. He developed a reputation for
reliability and honesty. Accordingly, in 1936, he was elected to the Nevada
State Assembly.
The Hoover
Dam is a concrete arch gravity dam in the Black Canyon of the Colorado River,
on the border between Nevada and Arizona. It was constructed between 1931 and
1936 during the Great Depression and was dedicated on 30 September 1935 by
President Franklin D. Roosevelt. Its construction was the result of a massive
effort involving thousands of workers, and cost over one hundred lives.
Originally known as Boulder Dam from 1933, it was officially renamed Hoover
Dam, for President Herbert Hoover, by a joint resolution of Congress in 1947.
Since about
1900, the Black Canyon and nearby Boulder Canyon had been investigated for
their potential to support a dam that would control floods, provide irrigation
water and produce hydroelectric power. In 1928, Congress authorized the
project. The winning bid to build the dam was submitted by a consortium called
Six Companies Inc. Construction on the dam began in early 1931. Such a large
concrete structure had never been built before, and some of the techniques were
unproven. The torrid summer weather and lack of facilities near the site also
presented difficulties. Nevertheless, Six Companies turned the dam over to the
federal government on 1 March 1936, more than two years ahead of schedule.
Hoover Dam
impounds Lake Mead, the largest reservoir in the United States by volume. The
dam is located near Boulder City, Nevada, a municipality originally constructed
for workers on the construction project, about 48 kileometres
southeast of Las Vegas, Nevada. The dam's generators provide power for public
and private utilities in Nevada, Arizona, and California.
River
view of the future dam site, c. 1904 Hoover Dam architectural
plans
Workers on a "Jumbo Rig"; used for drilling Hoover Dam's
tunnels
Soon after
the dam was authorised, increasing numbers of unemployed people converged on
southern Nevada. Las Vegas, then a small city of some 5,000, saw between 10,000
and 20,000 unemployed descend on it. A government camp was established for
surveyors and other personnel near the dam site. This soon became surrounded by
a squatters' camp. Known as McKeeversville, the camp
was home to men hoping for work on the project, together with their families.
Another camp, on the flats along the Colorado River, was officially called
Williamsville, but was known to its inhabitants as Ragtown.
When
construction began, Six Companies hired large numbers of workers, with more
than 3,000 on the payroll by 1932 and with employment peaking at 5,251 in July
1934. "Mongolian" (Chinese) labour was prevented by the construction
contract, while the number of African descent employed by Six Companies never
exceeded thirty, mostly lowest-pay-scale labourers in a segregated crew, who
were issued separate water buckets.
As part of
the contract, Six Companies Inc. was to build Boulder City to house the
workers. The original timetable called for Boulder City to be built before the
dam project began, but President Hoover ordered work on the dam to begin in
March 1931 rather than in October. The company built bunkhouses, attached to
the canyon wall, to house 480 single men at what became known as River Camp.
Workers with families were left to provide their own accommodations until
Boulder City could be completed, and many lived in Ragtown.
The site of Hoover Dam endures extremely hot weather, and the summer of 1931
was especially torrid, with the daytime high averaging 49 °C). Sixteen workers
and other riverbank residents died of heat prostration between 25 June and 26
July 1931.
The
Industrial Workers of the World, IWW or Wobblies, though much-reduced
from their heyday as militant labour organizers in the early years of the
century, hoped to unionise the Six Companies workers by capitalising on their
discontent. They sent eleven organizers, several of whom were arrested by Las
Vegas police. On 7 August 1931, the company cut wages for all tunnel workers.
Although the workers sent away the organizers, not wanting to be associated
with the Wobblies, they formed a committee to represent them with the
company. The committee drew up a list of demands that evening and presented
them to Crowe the following morning. He was noncommittal. The workers hoped
that Crowe, the general superintendent of the job, would be sympathetic;
instead he gave a scathing interview to a newspaper, describing the workers as malcontents.
On the
morning of 9 August 1931, Crowe met with the committee and told them that
management refused their demands, was stopping all work, and was laying off the
entire work force, except for a few office workers and carpenters. The workers
were given until 5 p.m. to vacate the premises. Concerned that a violent
confrontation was imminent, most workers took their pay cheques and left for
Las Vegas to await developments. Two days later, the remainder were talked into
leaving by law enforcement. On 13 August 1931, the company began hiring workers
again, and two days later, the strike was called off. While the workers
received none of their demands, the company guaranteed there would be no
further reductions in wages. Living conditions began to improve as the first
residents moved into Boulder City in late 1931.
A second
labour action took place in July 1935, as construction on the dam wound down.
When a Six Companies manager altered working times to force workers to take
lunch on their own time, workers responded with a strike. Emboldened by Crowe's
reversal of the lunch decree, workers raised their demands to include a
$1-per-day raise. The company agreed to ask the Federal government to
supplement the pay, but no money was forthcoming from Washington. The strike
ended.
Before the
dam could be built, the Colorado River needed to be diverted away from the
construction site. To accomplish this, four diversion tunnels were driven
through the canyon walls, two on the Nevada side and two on the Arizona side.
These tunnels were 56 ft (17 m) in diameter. Their combined length was nearly
16,000 ft, or more than five kilometres. The contract required these tunnels to
be completed by 1 October 1933, with a $3,000-per-day fine to be assessed for
any delay. To meet the deadline, Six Companies had to complete work by early
1933, since only in late fall and winter was the water level in the river low
enough to safely divert.
Tunnelling
began at the lower portals of the Nevada tunnels in May 1931. Shortly
afterward, work began on two similar tunnels in the Arizona canyon wall. In
March 1932, work began on lining the tunnels with concrete. First the base, or
invert, was poured. Gantry cranes, running on rails through the entire length
of each tunnel were used to place the concrete. The sidewalls were poured next.
Movable sections of steel forms were used for the sidewalls. Finally, using
pneumatic guns, the overheads were filled in. The concrete lining is one metre
thick, reducing the finished tunnel diameter to fifteen metres. The river was
diverted into the two Arizona tunnels on 13 November 1932. The Nevada tunnels
were kept in reserve for high water. This was done by exploding a temporary
cofferdam protecting the Arizona tunnels while at the same time dumping rubble
into the river until its natural course was blocked.
Following
the completion of the dam, the entrances to the two outer diversion tunnels
were sealed at the opening and halfway through the tunnels with large concrete
plugs. The downstream halves of the tunnels following the inner plugs are now
the main bodies of the spillway tunnels. The inner diversion tunnels were
plugged at approximately one-third of their length, beyond which they now carry
steel pipes connecting the intake towers to the power plant and outlet works.
The inner tunnels' outlets are equipped with gates that can be closed to drain
the tunnels for maintenance.
To protect
the construction site from the Colorado River and to facilitate the river's
diversion, two cofferdams were constructed. Work on the upper cofferdam began
in September 1932, even though the river had not yet been diverted. The
cofferdams were designed to protect against the possibility of the river's
flooding a site at which two thousand men might be at work, and their
specifications were covered in the bid documents in nearly as much detail as
the dam itself. The upper cofferdam was twenty nine metres high, and 230 metres
thick at its base, thicker than the dam itself. It contained 500,000 cubic
metres of material.
When the
cofferdams were in place and the construction site was drained of water,
excavation for the dam foundation began. For the dam to rest on solid rock, it
was necessary to remove accumulated erosion soils and other loose materials in
the riverbed until sound bedrock was reached. Work on the foundation
excavations was completed in June 1933. During this excavation, about 1.1
million cubic metres of material was removed. Since the dam was an arch-gravity
type, the side-walls of the canyon would bear the force of the impounded lake.
Therefore, the side-walls were excavated too, to reach virgin rock, as
weathered rock might provide pathways for water seepage. Shovels for the
excavation came from the Marion Power Shovel Company.
The men who
removed this rock were called high scalers. While suspended from the top
of the canyon with ropes, the high-scalers climbed down the canyon walls and
removed the loose rock with jackhammers and dynamite. Falling objects were the
most common cause of death on the dam site; the high scalers' work thus helped
ensure worker safety. To protect themselves against falling objects, some high
scalers took cloth hats and dipped them in tar, allowing them to harden. When
workers wearing such headgear were struck hard enough to inflict broken jaws,
they sustained no skull damage. Six Companies ordered thousands of what
initially were called hard boiled hats, later hard hats, and
strongly encouraged their use.
The cleared,
underlying rock foundation of the dam site was reinforced with grout, called a
grout curtain. Holes were driven into the walls and base of the canyon, as deep
as 46 metres into the rock, and any cavities encountered were to be filled with
grout. This was done to stabilize the rock, to prevent water from seeping past
the dam through the canyon rock, and to limit uplift or upward pressure
from water seeping under the dam. The workers were under severe time
constraints due to the beginning of the concrete pour, and when they
encountered hot springs or cavities too large to readily fill, they moved on
without resolving the problem. A total of 58 of the 393 holes were incompletely
filled. After the dam was completed and the lake began to fill, large numbers
of significant leaks into the dam caused the Bureau of Reclamation to look into
the situation. It found that the work had been incompletely done, and was based
on less than a full understanding of the canyon's geology. New holes were
drilled from inspection galleries inside the dam into the surrounding bedrock.
It took nine years, between 1938 and 1947, under relative secrecy to complete
the supplemental grout curtain.
The first
concrete was poured into the dam on 6 June 1933, 18 months ahead of schedule.
Since concrete heats and contracts as it cures, the potential for uneven
cooling and contraction of the concrete posed a serious problem. Bureau of
Reclamation engineers calculated that if the dam were to be built in a single
continuous pour, the concrete would take 125 years to cool, and the resulting
stresses would cause the dam to crack and crumble. Instead, the ground where
the dam would rise was marked with rectangles, and concrete blocks in columns
were poured, some as large as fifteen metres square and 1.5 metres high. Each
five-foot form contained a series of 23 mm steel pipes; cool river water would
be poured through the pipes, followed by ice-cold water from a refrigeration
plant. When an individual block had cured and had stopped contracting, the
pipes were filled with grout. Grout was also used to fill the hairline spaces
between columns, which were grooved to increase the strength of the joins.
The concrete
was delivered in huge steel buckets 2.1 metres and over a metre in diameter;
Crowe was awarded two patents for their design. These buckets, which weighed 20
short tons (18 t) when full, were filled at two massive concrete plants on the
Nevada side, and were delivered to the site in special railcars. The buckets
were then suspended from aerial cableways which were used to deliver the bucket
to a specific column. As the required grade of aggregate in the concrete
differed depending on placement in the dam, from pea-sized gravel to 23 cm
stones, it was vital that the bucket be manoeuvred to the proper column. When
the bottom of the bucket opened up, disgorging 6.1 cubic metres of concrete, a
team of men worked it throughout the form. Although there are myths that men
were caught in the pour and are entombed in the dam to this day, each bucket
deepened the concrete in a form by only an inch, and Six Companies engineers
would not have permitted a flaw caused by the presence of a human body.
A total of 2,480,000
cubic metres of concrete was used in the dam before concrete pouring ceased on
29 May 1935. In addition, 850,000 cubic metres were used in the power plant and
other works. More than 937 kilometres of cooling pipes were placed within the
concrete. Overall, there is enough concrete in the dam to pave a two-lane
highway from San Francisco to New York. Concrete cores were removed from the
dam for testing in 1995. They showed that Hoover Dam's concrete has
continued to slowly gain strength and the dam is composed of a durable
concrete having a compressive strength exceeding the range typically found in
normal mass concrete. Hoover Dam concrete is not subject to alkali–silica
reaction (“ASR”), as the Hoover Dam builders happened to use nonreactive
aggregate, unlike that at downstream Parker Dam, where ASR has caused
measurable deterioration.
With most
work finished on the dam itself (the powerhouse remained uncompleted), a formal
dedication ceremony was arranged for 30 September 1935, to coincide with a
western tour being made by President Franklin D. Roosevelt. The morning of the
dedication, it was moved forward three hours from 2 p.m. Pacific time to 11
a.m. This was done because Secretary of the Interior Harold L. Ickes had
reserved a radio slot for the President for 2 p.m. but officials did not
realize until the day of the ceremony that the slot was for 2 p.m. Eastern
Time. Despite the change in the ceremony time, and temperatures of 102 °F (39
°C), 10,000 people were present for the President's speech, in which he avoided
mentioning the name of former President Hoover, who was not invited to the
ceremony. To mark the occasion, a three-cent stamp was issued by the United
States Post Office Department bearing the name Boulder Dam, the official
name of the dam between 1933 and 1947. After the ceremony, Roosevelt made the
first visit by any American president to Las Vegas.
Most work
had been completed by the dedication, and Six Companies negotiated with the
government through late 1935 and early 1936 to settle all claims and arrange
for the formal transfer of the dam to the Federal Government. The parties came
to an agreement and on 1 March 1936, Secretary Ickes formally accepted the dam
on behalf of the government. Six Companies was not required to complete work on
one item, a concrete plug for one of the bypass tunnels, as the tunnel had to
be used to take in irrigation water until the powerhouse went into operation.
or