The
Daniel-Johnson Dam (), formerly known as
Manic-5, is a multiple arch buttress
dam on the
Manicouagan River which creates
Manicouagan Reservoir. The dam is composed of 14 buttresses and 13 arches and is north of
Baie-Comeau in
Quebec,
Canada. The dam was constructed between 1959 and 1970 for the purpose of
hydroelectric power production and supplies water to the Manic-5 and Manic-5-PA
power houses. The dam is tall, long and contains of concrete, making it the largest dam of its type in the world.
The dam was named after Daniel Johnson, Sr., the 20th Premier of Quebec who was responsible for starting the project. Johnson died on 26 September 1968, on the day he was to preside over the scheduled inauguration of the dam.. Although harnessing of this potential was considered interesting, its distance from major load centers and the lack of roads in the area were identified as major drawbacks. In addition, building dams in the wilderness was considered too costly.
After the Second World War, the discovery of large iron deposits on the North Shore and the increased forestry activity led to a rapid development of the region. The area's largest cities, Sept-Iles and Baie-Comeau, were now linked to the rest of the province by a road. At the same time, industrial development in southern Quebec required a larger electric supply. Improvements in long distance electric transmission technologies were also a consideration at the time. Significant advances in the field, including the construction of two 315-kilovolt lines, between the Bersimis complex, west of the Manicouagan system, and Montreal, (completed in 1956), lifted another obstacle.
In 1955, Hydro-Québec launched an 5-year extensive assessment of the Manicouagan's suitability. These studies demonstrated the exceptional potential of the river and stressed the advantages of building a multi-dam system in order take full advantage of the terrain and water flows. The data collected at the time was so promising that Hydro-Québec did not wait for the working group to submit their final recommendations. By 1959, a decision was made and construction of a access road from Baie-Comeau was started. The original project, the Manicouagan-Outardes project, included the construction of five dams on the Manicouagan River (Manic-1, Manic-2, Manic-3, Manic-4 and Manic-5) and three on the Outardes River (Outardes-2, Outardes-3 and Outardes-4). However, a miscalculation prevented the construction of the Manic-4 dam and powerhouse because engineers realized early on that it would encroach on the Manic-3 reservoir. Eventually, engineers would choose André Coyne's design for a multiple arch buttress dam as the most suitable and economical.
Construction
Construction on the dam's support facilities began in 1959 and the river diversion tunnels and foundation preparation commenced in 1960. To divert the Manicoagan River, workers blasted and dug two long and diameter tunnels through the gorge's solid granite west wall. Workers used "jumbo" drilling platforms and the tunnels progressed each shift. To facilitate the river's diversion, two
cofferdams were built. The first was a concrete arch upstream from the dam site which would block the river, forcing it into the diversion tunnels. The second cofferdam was downstream and prevented water from flowing back into the construction site. Each cofferdam was built on
alluvial deposits (loose soil) so they needed to be watertight which was accomplished with either a
grout curtain or deep supporting
piles. Once the river was diverted, workers pumped the remaining water out between the two cofferdams in order to prepare the site for construction. Once drained, workers excavated the alluvial deposits between the cofferdams creating a long pit that was deep at the center. This pit was then filled with concrete in the summer of 1962. To prevent seepage in the dam's foundation, a grout curtain was injected in the bedrock and a drainage network with of tunnels was constructed just downstream of the dam to collect water that may seep through.
After the extensive preparatory works were complete, the first concrete for the dam was poured on October 3, 1962. Concrete was poured day and night but was halted during the winter because of freezing temperatures. To organize the pouring, the dam was split into plots and each was raised about 5 or 6 ft. at a time. Workers had about 150 days - before seasonal flooding - to construct the dam to a height of at least . Before flooding began, engineers planned to seal the diversion tunnels and begin filling the reservoir. To speed the pouring process, concrete was poured in casts by buckets that moved along three cableways suspended above the construction site. The deadline was met within the 150 days and a total of of concrete was poured. although relations between the Liberal leader and his former cabinet minister were strained by Lévesque's recent defection to the Mouvement Souveraineté-Association, a precursor of the Parti Québécois.
In his authorized biography, Hydro-Québec executive, Robert A. Boyd, recalls being woken up at 6 a.m. the next morning by his boss, Roland Giroux. "I've got bad news, Robert...", said Giroux, adding that he just found the Premier lying dead in his bed. Johnson's sudden demise sent shock waves at the work-site and across the province and the dedication ceremony was quickly canceled.
On September 26, 1969, a year to the day after Johnson's death, the new Premier Jean-Jacques Bertrand accompanied by Johnson's widow and children, unveiled two plaques and officially dedicated the dam after his predecessor. Both plaques now sit side by side at the top of the complex.
Facilities
Dam
The design was chosen for strength and economical reasons as it used less concrete or material than a
gravity or
embankment dam. The Daniel-Johnson Dam is a tall and long multiple-arch buttress dam. Of the dam's 14 total buttresses, the two that form the center arch are apart at their base while the others are about apart. At its thickest point, the center, the dam is wide while the crest can reach about wide. Pressure from water behind the dam is transferred from the dam's arches to its buttresses and lastly into the ground or its foundation.
The dam was constructed with a high-quality concrete designed to withstand constant thawing and freezing associated with its environment. To further help the structure cope with the climate, engineers placed one inch steel reinforcing bars within the upstream and downstream faces of the dam. The concrete's strength in compression was initially 4,500 lbs. per square inch to meet an estimated 1,500 PSI within the structure. The upstream face of the dam was also coated in asphalt for protection against water. Despite the strength of the dam's concrete, two parallel inclined cracks were discovered on one of the arches shortly after construction.
Reservoir
The dam impounded the Manicougan River, which filled the Earth's fifth largest confirmed
impact crater, the
Manicouagan crater, creating Manicouagan Reservoir. Coincidentally, the reservoir itself is the fifth largest in the world as well. The reservoir has a maximum depth of feet, mean depth of and contains of water. While draining an area of , it has a surface area of and shoreline of .
The reservoir is a well known area for Atlantic salmon, lake trout and northern pike fishing, although tall trees flooded during the impoundment have not decomposed due to a lack of oxygen, which can sometimes interfere with the sport.
The priming of the reservoir also created a large artificial island in the center of the Manicouagan reservoir by merging two crescent-shaped lakes: Mouchalagane Lake on the western side and Manicouagan Lake on the eastern side. Covering an area of , René-Levasseur Island is considered to be the second largest island in the world located in a lake, in terms of area (the largest is Manitoulin Island in Lake Huron).
The island was named after René Levasseur, the chief engineer responsible for the construction of the Daniel-Johnson dam. Levasseur died at the age of 35, only days before the dam's inauguration.
The designers of the Manic-5 decided on an above ground power house that was downstream of the dam for safety and cost. The intake was built on the east side of the dam and supplies two , long diameter concrete-lined penstocks (tunnels). Just before reaching the power house and its eight turbines, each penstock splits into four branches. The power house is about downstream of the dam and utilizes two surge tanks for sudden rises in water pressure from the two penstocks. Each surge tank has a diameter expansion chamber and is about higher than the actual dam structure. The surge tanks protect the penstocks and turbines from water hammer which would occur if the turbine gates were quickly closed and water pressure suddenly increases.
Cultural and political significance
The construction of the Daniel-Johnson Dam and the Manic-Outardes complex happened in a larger social and political context of the Quiet Revolution in Quebec, a time when recently nationalized "Hydro-Québec rapidly becomes a symbol of the new Quebec nationalism and of the new economic strategy of the State", explains historian Paul-André Linteau.
This newfound euphoric attitude is found in newspapers of the period. In a series of papers published in Montreal's La Presse, Renaude Lapointe calls Hydro-Québec a "colossus on the march". In this context, the construction of the complex is closely followed by the public and becomes part of the popular culture of that era.
For instance, chansonnier Georges Dor penned his huge 1966 hit, La Manic. The song tells the story of a construction worker at the remote jobsite who describes his loneliness to his wife in words that captured the collective imagination of the Quebec public.
Belgian-born novelist Henri Vernes was also inspired by the gigantic project and made the Manic-5 project the setting of one of his Bob Morane adventure novels. Terreur à la Manicouagan is about an attempt by arch-villain Roman Orgonetz to breach the dam by destroying the surge chamber by remote-controlled detonation, a plan foiled by Morane and his Scottish sidekick, Bill Ballantine. Prior to writing his novel, Vernes spent some time at the worksite, at the invitation of the Quebec government and Hydro-Québec. The book was launched in 1965 at the Hydro-Québec Building in Montreal.
Other notable visitors to the construction site included famous cartoonist Hergé, who left an original drawing of his characters Tintin the reporter and his dog Snowy posing in front of a ligne claire depiction of the dam. A colorized version of the autographed drawing is featured at the Jean-Lesage generating station visitor's center, north of Baie-Comeau.
In the late 60s, a Montreal-based public relations officer with Renault Canada, Jacques About, was asked by the company to study the feasibility of introducing the Renault Alpine sports car into Canada. About's survey showed some potential but the manufacturer ultimately decided against introducing the model in its North American offerings. The Montrealer decided to leave the company and start his own manufacturing business, Automobiles Manic Inc., in 1968. After gaining financial support from public and private backers, including Bombardier and Steinberg's supermarkets, his company started building a 2-seat sport coupe based on the Alpine A110, the Manic GT. Due to disappointing sales, the company stopped making the car in 1971..
The hydroelectric project also gave its name to Montreal's first foray into professional soccer, the short-lived Montreal Manic. The franchise competed for three seasons in the North American Soccer League in the early 80s. In March 2000, the Canada Post Corporation issued a 46 cent stamp featuring the Dam as part of a 4-stamp Millenium Collection sheet depicting "engineering and technological marvels".
Guided tours
The dam is also a tourist attraction. Since the 1960s, Hydro-Québec organizes four daily tours of the facility between June 24, Quebec's National Day, and August 31. Off-season tours can also be arranged by appointment. The 2-hour tour includes a briefing on the construction and operation of the facility, a visit of the Manic-5 powerhouse and a bus ride to the base and the crest of the Daniel-Johnson dam, which offers a spectacular panorama of the Manicouagan River valley. A belvedere, accessible by car 5 minutes away, is a nice picnic spot and offers the visitor a majestic view of the dam, which is lit at night . The incident led to the resignations of Hydro-Québec's CEO André Caillé, and chairman of the Board André Bourbeau, less than two months later.
To access the dam from Baie-Comeau, visitors must take the narrow, winding Route 389. The dam is about 3 hours away. In 2009, 8,217 people visited this remote facility.
See also
Jean-Lesage generating station
René-Lévesque generating station
* Hydro-Québec's electricity transmission system
History of Hydro-Québec
List of conventional hydroelectric power stations
List of power stations in Canada
References
Further reading
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External links
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Category:Manicouagan-Outardes hydroelectric project
Category:Dams in Quebec
Category:Buttress dams
Category:Arch dams
