Description: The Beauharnois generating station and dam are located at the mouth of the Beauharnois Canal, located in the same municipality. Its construction began in 1929, 'with pick and shovel'. One kilometer long, it is one of the most imposing of its kind still to this day on the planet.

The Beauharnois dam is a concrete structure, comprising a water intake, a powerhouse, two gravity dams located on the left bank and the right bank, at each end, as well as the spillway. Thanks to its length, the Beauharnois power station has 36 turbine-generator groups, for an installed power of 1673MW.

It's hard to imagine that when the work began, we were building a hydroelectric power station and a dam in the middle of a field.

Description: La centrale et le barrage de Beauharnois se situent à l'embouchure du Canal de Beauharnois, situé dans la même municipalité. Sa construction s'est amorcée en 1929, 'au pic et à la pelle'. Longue d'un kilomètre, il s'agit de l'une des imposantes du genre encore à ce jour sur la planète.

Le barrage de Beauharnois est un ouvrage en béton, comprenant une prise d’eau, une centrale, deux barrages poids situés en rive gauche et en rive droite, à chaque extrémité, ainsi que l’évacuateur. Grâce à sa longueur, la centrale de Beauharnois compte 36 groupes turbine-alternateur, pour une puissance installée de 1673MW.

Difficile à concevoir que lors du début des travaux, on construisait une centrale hydroélectrique et un barrage en plein milieu d'un champ.

Submitted By: Valérie Fréchette

City: Montréal

Region: Quebec

Benefits to society [Translate]

In addition to allowing hydroelectric production for the greater Montreal area, the development of Beauharnois has enabled the economic and societal development of the region. The creation of the Beauharnois development was made possible through a Crown Land Surrender Agreement, the Boundary Waters Treaty, which led to the creation of the International Joint Commission (IJC). The IJC is an objective and independent committee whose mandate is to prevent and resolve disputes between the two countries for projects affecting boundary and transboundary water bodies. Article VIII of the treaty provides an order of precedence for the use of water and avoids conflicts of use, namely:

1. Domestic and sanitary uses (including municipal water supply and wastewater treatment);
2. Uses for navigation
3. Uses for power generation and irrigation

Eventually, the development of the layout allowed the evolution of the canal, the installation of locks and the creation of the St. Lawrence Seaway.

Economic benefits [Translate]

The construction of the Beauharnois facility allowed the commissioning of the St. Lawrence Seaway (VMSL), a trade route that allows the transport of goods to the heart of America, i.e. the Great Lakes region. Several ports are located around these lakes, and are linked to the rail networks for the transport of goods to various North American destinations. The main types of cargo transported are grain, iron ore, processed iron and steel, coal, stone and aggregates, containers and petroleum products. In addition, many hydroelectric developments are located along the VMSL and provide electricity to several North American cities. The VMSL is also used for recreational purposes by many boaters. The economic activities linked to the VMSL create direct jobs (linked to the transport of goods from port activities and related transport), indirect jobs (linked to the purchase of goods and services by the ports from suppliers) and induced jobs (linked to the local and regional economy of the port due to the purchase of housing, clothing and food by direct workers). In 2017, more than 38.1 million metric tons passed through the VMSL, representing a value of C$10 billion of goods. For VMSL, the transport of grain and iron ore are the most important. The economic benefits represent C$16.8 billion of economic activity in Canada.

Technical merits [Translate]

The overburden deposits in place at the site of the future Beauharnois Canal are composed of highly plastic marine silty clay from the Champlain Sea. The foundation conditions, as well as the need for a large quantity of channel excavation spoil, consisting of reworked clay, controlled the geometry and design of the embankments. Several typical sections have been developed to meet the variable overburden foundation conditions encountered along the canal. Thus, the typical sections include at least 2 berms (upstream and downstream) and sometimes additional berms, to contain the hydraulic spoil from the excavation of the canal. Breakaways have been integrated into the design, under the reworked clay embankments, to ensure continuity between the natural clay of the foundation and the body of the structure. The Beauharnois Canal was dug using a hydraulic dredge with buckets. This equipment excavated the saturated marine clay and deposited it in these previously constructed basins. During the early phases of construction, landslides occurred along the dykes. Karl Terzaghi, from his 1946 survey, considered that the natural water content, which varied along the natural foundations, was well above its liquid limit. Thus, the construction process produced a disturbed clay whose unconfined compressive strength was twenty times lower than that of an undisturbed sample. Over time, the reworked clay regained some of its strength.

Historical background [Translate]

Faced with the navigation difficulties encountered in the old Beauharnois Canal, the Beauharnois Light Heat & Power company launched the construction of the new Beauharnois Canal in 1929. The purpose of this work was to develop maritime trade as well as the hydroelectric potential of the river. The first units of the new power station were commissioned in 1932. The economic crisis of the early 1930s delayed the completion of the first section of the Beauharnois power station. Groups were added regularly over the following years to complete the first power station in 1948, with 14 groups plus two auxiliary groups. After the Second World War, the demand for electricity increased rapidly and in 1948 the construction of the second phase of the Beauharnois power station began. Between 1948 and 1953, 12 additional units were added to the plant. The first units were commissioned in 1951 and the last in 1953. To meet demand, Hydro-Québec began construction in 1956 of the third and final phase of the Beauharnois generating station. The generators in this last section of the plant were commissioned between 1959 and 1961. Ten new generators were therefore added, for a total of 38 generators, taking into account the two auxiliary generators, for an installed capacity of 1,673 MW.

The final works for the construction of the Beauharnois lock, as well as the last expansion of the power station contributed to the official opening of the VMSL on June 26, 1959.

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