Robert-Bourassa Generating Station
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The Robert-Bourassa generating station, formerly known as La Grande-2 (LG-2), is a
hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...
power station on the
La Grande River La Grande River (french: La Grande Rivière; cr, Chisasibi, script=latn; both meaning "great river") is a river in northwestern Quebec, Canada, which rises in the highlands of north central Quebec and flows roughly west to drain into James Bay. ...
that is part of
Hydro-Québec Hydro-Québec is a public utility that manages the generation, transmission and distribution of electricity in the Canadian province of Quebec, as well as the export of power to portions of the Northeast United States. It was established by the ...
's
James Bay Project The James Bay Project (french: projet de la Baie-James) refers to the construction of a series of hydroelectric power stations on the La Grande River in northwestern Quebec, Canada by state-owned utility Hydro-Québec, and the diversion of neigh ...
in
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
. The station can generate 5,616 MW and its 16 units were gradually commissioned between 1979 and 1981. Annual generation is in the vicinity of 26500 GWh. Together with the adjacent 2,106 MW La Grande-2-A generating station (LG-2-A), commissioned in 1991–1992, it uses the
reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...
and
dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use ...
system of the
Robert-Bourassa Reservoir The Robert-Bourassa Reservoir () is a man-made lake in northern Quebec, Canada. It was created in the mid-1970s as part of the James Bay Project and provides the needed water for the Robert-Bourassa and La Grande-2-A generating stations. It has a ...
to generate electricity. The two plants taken together account for more than 20% of Hydro-Québec's total installed capacity of 36,810 MW in 2009. It is Canada's largest hydroelectric power station, ranks in 12th place on the
list of largest hydroelectric power stations This article provides a list of the largest hydroelectric power stations by generating capacity. Only plants with capacity larger than 3,000 MW are listed. The Three Gorges Dam in Hubei, China, has the world's largest instantaneous generating cap ...
and is the world's largest
underground power station An underground power station is a type of hydroelectric power station constructed by excavating the major components (e.g. machine hall, penstocks, and tailrace) from rock, rather than the more common surface-based construction methods. One or mor ...
. Initially known as La Grande-2, it was renamed after
Robert Bourassa Robert Bourassa (; July 14, 1933 – October 2, 1996) was a Canadian lawyer and politician who served as the 22nd premier of Quebec from 1970 to 1976 and from 1985 to 1994. A member of the Liberal Party of Quebec, he served a total of just un ...
who, as
Premier of Quebec The premier of Quebec ( French: ''premier ministre du Québec'' (masculine) or ''première ministre du Québec'' (feminine)) is the head of government of the Canadian province of Quebec. The current premier of Quebec is François Legault of the ...
(1970–1976 and 1985–1994) gave the James Bay Project a vital political impetus.


Context

The Robert-Bourassa generating station is the main facility of the James Bay hydroelectric project, a large
hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...
complex built on the
La Grande River La Grande River (french: La Grande Rivière; cr, Chisasibi, script=latn; both meaning "great river") is a river in northwestern Quebec, Canada, which rises in the highlands of north central Quebec and flows roughly west to drain into James Bay. ...
, a large river in Quebec's sparsely populated
northern Quebec Northern Quebec (french: le nord du Québec) is a geographic term denoting the northerly, more remote and less populated parts of the Canadian province of Quebec.Alexandre Robaey"Charity group works with Indigenous communities to feed Northern Quebe ...
. It was also the first to be built, between 1974 and 1981. It was inaugurated by Premier
René Lévesque René Lévesque (; August 24, 1922 – November 1, 1987) was a Québécois politician and journalist who served as the 23rd premier of Quebec from 1976 to 1985. He was the first Québécois political leader since Confederation to attempt ...
of Quebec, on October 27, 1979. Conception work on the generating station, dam and reservoir began in October 1970 when Montreal-based engineering firm Rousseau Sauvé Warren (RSW) was given by Hydro-Québec to make the case for the development of the La Grande River. Another engineering firm, Asselin, Benoît, Boucher, Ducharme & Lapointe (ABBDL) was tasked with a feasibility study on the more southerly NBR (Nottaway, Broadback, Rupert) concept. At RSW the development of the La Grande River was championed by François Rousseau, one of firm's associates and a former Hydro-Québec senior engineer. A final decision to build the hydroelectric complex on the La Grande hydrographic system was made in 1972, after engineers determined the NBR project would be less cost effective because of the
silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...
y nature of the soils in the NBR area. The La Grande option had the added advantages of a lesser impact on First Nations hunting and fishing, on the boreal forest and would require less flooding.


Construction

The main dam is located from the mouth of the river, in the transition zone between the plateau and the coastal plain, and has a maximum height of . Twenty-nine dykes of various sizes close the reservoir. They are organized in three group: dykes D1-D4 are located north of the spillway, nicknamed the ''Staircase of the Giants'', D5-D14 are located on the left shore of the river while a third group, nicknamed the ''Duncan dykes'' (D17-D27), are located south. The dam and dykes hold a reservoir covering an area of with a useful capacity of 19.365 billion m³. The generating station itself is located
underground Underground most commonly refers to: * Subterranea (geography), the regions beneath the surface of the Earth Underground may also refer to: Places * The Underground (Boston), a music club in the Allston neighborhood of Boston * The Underground (S ...
, downstream from the main dam. It hosts 16 Francis turbines, set up in two groups of eight each. In 1974, in what was one of the most extreme cases of workplace
sabotage Sabotage is a deliberate action aimed at weakening a polity, effort, or organization through subversion, obstruction, disruption, or destruction. One who engages in sabotage is a ''saboteur''. Saboteurs typically try to conceal their identitie ...
up to that time, workers at the La Grande-2 site used bulldozers to topple electric generators, damage fuel tanks, and set buildings on fire. The project was delayed a year, and the direct cost of the damage estimated at $2 million CAD. The causes were not clear, however three factors have been cited: inter-union rivalry, poor working conditions, and the perceived arrogance of American executives at the contractor,
Bechtel Corporation Bechtel Corporation () is an American engineering, procurement, construction, and project management company founded in San Francisco, California, and headquartered in Reston, Virginia. , the '' Engineering News-Record'' ranked Bechtel as ...
.


Road

The first step towards the construction of the La Grande-2 generating station took place in June 1971, in
Matagami Matagami (, ) is a small town in Quebec, Canada. It is located north of Amos, on Matagami Lake, at the northern terminus of Route 109 and the start of the James Bay Road (French: ''Route de la Baie James''). It is enclaved within the local mu ...
, a small mining town located south of La Grande River. Engineering firm Desjardins, Sauriol and Associates were tasked with the construction of a basic road to the future site and the Cree settlement at Fort George. The deadline was tight: in 450 days. The first challenge involved deploying teams of land surveyors and lumberjacks by seaplanes and helicopters to clear a path for a permanent road. Parallel to the path, a few kilometres away, an
ice road An ice road or ice bridge is a human-made structure that runs on a frozen water surface (a river, a lake or a sea water expanse).Masterson, D. and Løset, S., 2011, ISO 19906: Bearing capacity of ice and ice roads, Proceedings of the 21st Inte ...
was built to move heavy machinery north. The first milestone was reached on February 11, 1972, with the opening of the ice bridge crossing the Rupert River. The temporary road reached the La Grande River in December 1972, allowing the minimum necessary level of access needed to begin work – namely to construct housing for the thousands of people who would work on the dam for the next decade. A permanent road surfaced with gravel was completed on October 20, 1974, at a cost of $348 million, and was paved over the next two years.


Temporary diversion

The first stage of construction was the temporary diversion of the La Grande River; the tunnels had to be big enough to protect the construction site from floods, but not so large as to unnecessarily increase cost. Two diversion tunnels were drilled into the left bank of the river and were opened on April 27, 1975. For the next three and a half years the flow of the river would be diverted through the tunnels. Each tunnel was wide and high; the north tunnel was long and the south, . The tunnels were designed to carry the 65-year flood flow of the La Grande River, calculated at . Since the original construction schedule called for completion on February 15, 1980, the south diversion tunnel was scheduled to be closed in November 1978, during low river flows in the winter. However, the deadline was revised forward by 60 days, and the tunnel had to be reinforced to withstand harsh autumn conditions. After the dam was completed, the tunnels are still used as flood control
outlet works A gatehouse, gate house, outlet works or valve house for a dam is a structure housing sluice gates, valves, or pumps (in which case it is more accurately called a pumping station). Many gatehouses are strictly utilitarian, but especially in the n ...
and have a design flow of .


Dam and dykes

The Robert-Bourassa dam is located from the mouth of the La Grande River, in the transition zone between the Laurentian Plateau (the elevated
Canadian Shield The Canadian Shield (french: Bouclier canadien ), also called the Laurentian Plateau, is a geologic shield, a large area of exposed Precambrian igneous and high-grade metamorphic rocks. It forms the North American Craton (or Laurentia), the anc ...
) and the coastal plain. It has a maximum height of and is long at the crest. The core of the earthfill dam is made of glacial
moraine A moraine is any accumulation of unconsolidated debris (regolith and rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a glacier or ice shee ...
which is impervious, and available in large quantities within a radius of the dam site, due to extensive glaciation of the area during the last
ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...
. The core is slightly inclined upstream, to increase resistance against the immense pressure of water in the reservoir. The layers above consist of fill zones of varying coarseness, and is surfaced with
riprap Riprap (in North American English), also known as rip rap, rip-rap, shot rock, rock armour (in British English) or rubble, is human-placed rock or other material used to protect shoreline structures against scour and water, wave, or ice erosion. ...
to reduce erosion. The original plan envisioned the construction of a
concrete-face rock-fill dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, ...
, but this was rejected in favor of a more conventional embankment design, partly because of the lower cost, and also because the concrete face would have to be inspected from time to time requiring drainage of the reservoir. Because of the huge size of the reservoir, this would be essentially impossible. In order to hold the reservoir at its operating height of , 29 dikes surround the reservoir basin at various locations. Dikes D-1 to D-4 are located immediately to the north; D-5 to D-14 (the "Forebay dikes") to the south; and D-17 to D-27 (the "Duncan dikes") about further south. They range in size from D-26B, long, to D-20, long.


Reservoir

Covering an area of – greater in size than
Luxembourg Luxembourg ( ; lb, Lëtzebuerg ; french: link=no, Luxembourg; german: link=no, Luxemburg), officially the Grand Duchy of Luxembourg, ; french: link=no, Grand-Duché de Luxembourg ; german: link=no, Großherzogtum Luxemburg is a small lan ...
– the vast Robert-Bourassa Reservoir is fed by an upstream catchment of , plus water diversions from the
James Bay Project The James Bay Project (french: projet de la Baie-James) refers to the construction of a series of hydroelectric power stations on the La Grande River in northwestern Quebec, Canada by state-owned utility Hydro-Québec, and the diversion of neigh ...
, the
Caniapiscau Reservoir The Caniapiscau Reservoir () is a reservoir on the upper Caniapiscau River in the Côte-Nord administrative region of the Canadian province of Quebec. It is the largest body of water in Quebec and the second largest reservoir in Canada. The C ...
and the EOL (
Eastmain Eastmain ( ; cr, ᐄᔅᒣᐃᓐ/Îsmein) is a Cree community located on east coast of James Bay at the mouth of the Eastmain River, Quebec, Canada. It is a small coastal Cree village with a population of 924 people in the 2021 Canadian Censu ...
- Opinaca-La Grande) diversion project. About is active or usable storage for power generation, out of a total volume of . Because of its great size, it is inhabited by a diverse array of aquatic flora and fauna. On November 27, 1978, the diversion tunnels were closed and water began to back up behind the dam. The enormous reservoir took over a year to completely fill. The water initially rose very fast: during the first week, with on the first day alone. The reservoir reached its minimum operational level of on September 2, 1979, and reached its normal maximum level of in December 1979.


Dessaulniers pump station

The construction of the Duncan dikes partially blocked the flow of the Dessaulniers River, which is located to the southeast of the Robert-Bourassa Reservoir. The river flowed into Dessaulniers Lake at an elevation of , below the level of the Robert-Bourassa Reservoir. To prevent the flooding of an additional and preserve the lake in its natural state, a pump station was installed which removes water from the Dessaulniers to the Robert-Bourassa Reservoir. The pump station was designed to remove an annual average of , from a drainage area of . The pump station was commissioned in June 1977. It has four pumps with a capacity of each, with a maximum lift of . Each pump is powered by a 1,120 KW (1,500 hp) motor. The pumping station also served to divert water away from the Dessaulniers river bed, during the construction of dike D-20.


Spillway

The
spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...
, nicknamed ''Staircase of the Giants'', is near the north end of the main dam and is part of dike D-4. It consists of a concrete control structure and a man-made waterfall discharging into a stilling basin below the dam. The spillway has eight wide gates, separated by thick columns. The gates are opened and closed by cable
winch A winch is a mechanical device that is used to pull in (wind up) or let out (wind out) or otherwise adjust the tension of a rope or wire rope (also called "cable" or "wire cable"). In its simplest form, it consists of a spool (or drum) attache ...
es, in order to control spills. The eight gates are all opened at the same time once every 15 years. Having passed through the gates, the kinetic energy of the water is dissipated in a basin at the foot of the control structure. It then flows down a long rock channel with a vertical drop of on its way back into the La Grande river. The channel has 10 steps ranging from in height and in length. The flow rate increases from at the top of the spillway to at the bottom.


Generating station

The Robert-Bourassa hydroelectric station, formerly named La Grande-2 or LG2, is located underground about downstream of the main dam. With an installed capacity of 5,616
megawatt The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units, International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), ...
s, it is the largest power station owned by Hydro-Québec, and the largest underground power station in the world. On October 27, 1979, 3,000 people gathered for the dedication of the power plant by Quebec Premier
René Lévesque René Lévesque (; August 24, 1922 – November 1, 1987) was a Québécois politician and journalist who served as the 23rd premier of Quebec from 1976 to 1985. He was the first Québécois political leader since Confederation to attempt ...
. The underground complex, including a service tunnel, the generation room and a
surge chamber Surge means a sudden transient rush or flood, and may refer to: Science * Storm surge, the onshore gush of water associated with a low-pressure weather system * Surge (glacier), a short-lived event where a glacier can move up to velocities 100 ...
, required the excavation of of material. The plant was constructed by Rousseau Sauvé Warren (RSW) of Montreal. Unlike other facilities in the James Bay Project, the LG2 was constructed to imperial rather than metric specifications, even though Canada had converted to the metric system in the 1970s. The power station can be accessed either by an elevator or a tunnel. The plant has 16
Francis turbine The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency. The proces ...
s, divided into two sets of eight each, and separated by a mounting area, workshops, control room, elevator shaft and ventilation system. The turbines were built by two partners of
James Bay Energy The Société d'énergie de la Baie James is the company in charge of building the hydroelectric development known as the James Bay Project in northern Quebec. It was established in December 1971 by the ''Société de développement de la Baie Jam ...
(SEBJ). Units 1, 3, 5, 7, 10, 12, 14 and 16 were built by Marine Industries Limited (MIL), while units 2, 4, 6, 8, 9, 11, 13 and 15 were built by
Canadian General Electric GE Canada (or General Electric Canada) is the wholly-owned Canadian unit of General Electric, manufacturing various consumer and industrial electrical products all over Canada. GE Canada was preceded by the company Canadian General Electric (CG ...
(alternators) and
Dominion Engineering Works also produced hydraulic presses with the brand name "speed-hy-matic" a high speed hydraulic press, Dominion Engineering Works was a company with headquarters in Montreal, Quebec Montreal ( ; officially Montréal, ) is the second-most pop ...
(turbines). The two groups have somewhat different characteristics. The turbines manufactured by MIL are lighter, 96 tonnes compared to 111, and have fifteen blades, compared to 11 for the other group. Each turbine is rated at 339 MW at a head and a speed of 133.33 rpm. The generators are rated at 370
megavolt ampere A volt-ampere ( SI symbol: V⋅A or V A, simplified as VA) is the unit for the apparent power in an electrical circuit. The apparent power equals the product of root mean square voltage (in volts) and root mean square current (in ampere ...
s (MVA), which is increased to 390 MVA in the winter.


La Grande-2-A


Photos

Image:Bourassa power plant.jpg, Main entrance of the underground generating station. Image:Réservoir R-B.jpg, The Robert-Bourassa Reservoir, near the generating station. Image:Transformateur CentraleR-B.jpg, Electric transformers at the plant's switchyard.


See also

*
List of largest power stations in Canada This article lists the largest electrical generating stations in Canada in terms of current installed electrical capacity. Non-renewable power stations are those that run on coal, fuel oils, nuclear, natural gas, oil shale and peat, while renewa ...
*
List of conventional hydroelectric power stations This article lists hydroelectric power stations that generate power using the conventional dammed method. This list includes power stations that are larger than in maximum net capacity, and are operational or under construction. Those power sta ...
*
List of hydroelectric stations in Quebec The following page lists electrical generating stations in Quebec, Canada. Quebec produces close to 96% of its electricity through hydropower. The James Bay Project is Quebec's largest generation complex, with an installed capacity of 16,527 mega ...
*
Reservoirs and dams in Canada This is a list of dams and water reservoirs in Canada. Alberta * Bassano Dam * Bearspaw Dam *Bighorn Dam * Brazeau Dam * Cascade Dam *Dickson Dam * Ghost Dam *Glenmore Reservoir * Interlakes Dam *Milk River Ridge Reservoir * Old Man River Dam * ...


References


Works cited

* (also available in English, under the title ''Hydro-Québec After 100 Years of Electricity'') * . * . * . * .


External links


Hydro-Québec - Robert-Bourassa Generating Facility
{{JamesBay James Bay Project Dams completed in 1981 Dams in Quebec Dams on the La Grande River Publicly owned dams in Canada