Verzasca Dam
Encyclopedia
The Contra Dam, commonly known as the Verzasca Dam and the Locarno Dam, is an arch dam
on the Verzasca River
in the Val Verzasca
of Ticino
, Switzerland
. The dam creates Lago di Vogorno
2 km (1.2 mi) upstream of Lake Maggiore
and supports a 105 MW hydroelectric power station
. It was constructed between 1961 and 1965 and starting shortly after its reservoir
was filled, a series of earthquakes related to its water load occurred until 1971. The dam is owned and operated by Verzasca SA and is the fourth tallest in Switzerland.
The dam became a popular bungee jumping
venue after a James Bond
stuntman jumped off it in the opening scene of the 1995 film GoldenEye
; a stunt voted as the best movie stunt of all time in a 2002 Sky Movies
poll.
s were constructed, one of which redirected the river through a diversion tunnel with a 200 m3/s capacity. As the river can have flows much higher than the tunnel's capacity, this was accepted as a risk by engineers. Excavation of the right side of the dam had to be expanded due to unforeseen weathered rock and designs were altered within 15 days.
Concrete pouring and placement occurred for 18 months, of which the maximum poured in a day was 3100 cubic metre and in a month, 55000 cubic metre. The aggregate
for the concrete was obtained from a quarry near the construction site. The high-quality and strength gneiss
-rock was ground in a rotary crusher and prepared in the concrete mixture. To facilitate the contraction and settling of the concrete in the dam, it was cooled with a series of steel pipes that ran throughout the mass of concrete, with the exception of the top 30 m (98.4 ft) of the dam. A grout curtain
was placed around and below the dam as well to prevent leakage, which consumed a large amount of cement. In August 1964, the reservoir began to fill and in September 1965, the reservoir was full and the dam completed.
, the dam's designer, described as an "exceptionally rapid rise of water during the first filling" of the reservoir, beginning in August 1964, there were seismic shocks. The earthquake
s began in May 1965 and the biggest shocks had occurred later in October and November after the reservoir was full. The epicenters were located at two faults near the dam. As many as 25 shocks occurred a day. The shocks stopped once the reservoir was emptied and no damage was found. After refilling, the shocks decreased and an "equilibrium" was believed to have been reached, one that did not respond to variations in water load. Another large shock occurred several years after filling. By 1971, there were no more seismic shocks around the dam or reservoir. No known detailed geological studies were conducted prior to construction of the dam and several faults are known to exist in the area.
slender arch dam
with a height of 220 m (721.8 ft) and crest length of
380 m (1,246.7 ft). The dam is 25 m (82 ft) wide at its base and 7 m (23 ft) wide at its crest. The dam structure contains 660000 cubic metre of concrete and the structure itself has a surface area of 44500 square metre. The dam is slender in design and its horizontal arches are in an elliptical shape. The horizontal curvature of the dam decreases from the center of the dam towards its abutments and the curvature from the center of the arches increases from the crest down to the foundation. The thickness is constant with the exception of where the dam is received by its abutments; here it is thicker to reduce pressure on the rock. The strong rock can accept stresses of 70 kg/cm2. Vertically, the thickness of the dam increases from the crest down to the foundation and has a slight curve from the center towards the crest. This helps alleviate tensile stress for when the reservoir is not only full but empty. The dam's outlet works
consist of two discharge pipes, capable releasing up to 170 m3/s each. One discharges into the original diversion tunnel and another is located at the base of the dam and discharges into the river valley below.
The dam creates Lago di Vogorno
which has a 105000000 cubic metre capacity and surface area of 160 ha (395.4 acre), collected from a catchment area of 230 km² (88.8 sq mi). The Verzasca River has very irregular seasonal flows which can reach as high as 1000 m3/s.
Dr. Lombardi considers it one of his most aesthetically pleasing dams, primarily because of the slenderness of the concrete arch and the "outstanding cleanness of the design." The design also reduced the amount of concrete needed, therefore reducing the cost as well.
s, each located on the structure, near its abutments on either side which have a maximum discharge capacity of 1300 m3/s. Each spillway contains six fixed-crest weir
s that are 12 m (39.4 ft) wide. From each opening, the water flows down a single chute to a flip bucket at the bottom of the spillway. The flip buckets dissipate and deflect the water towards the center axis of the valley 200 m (656.2 ft) below. The spillways were later modified to improve releases and function by increasing the size of the piers and adding additional lateral deflectors near the crest.
that contains 3 x 35 MW Francis turbine
s and generates and average of 234 GWh annually. Water from the reservoir at 470 m (1,542 ft) above sea level is transferred to an underground power station
downstream at 193 m (633.2 ft) above sea level, affording a maximum hydraulic head
of 277 m (908.8 ft). The power plant can discharge up to 50 m3/s of water which exits via a 1.9 km (1.2 mi) tailrace tunnel into Lago di Verbano. The builder and owner is Verzasca SA has an 80-year concession on the power station which will expire in 2046.
film GoldenEye
featured Bond jumping off the dam. The stunt was performed by British stuntman
Wayne Michaels. The jump was voted as best movie stunt of all time in a 2002 Sky Movies
poll. The dam doubled as the fictional Arkhangelsk
Chemical Weapons Facility located in the northern Soviet Union during the Cold War
.
Contestants bungee jumped off the dam as a Roadblock task in the first episode of the 14th season
of The Amazing Race
.
The dam owners started to lease access to the dam, soon after GoldenEye was released, to a commercial bungee jump
operator. According to the operator, over 10,000 people have jumped the 220 m (720 ft) from the dam.
Arch dam
An arch dam is a type of dam that is curved and commonly built with concrete. The arch dam is a structure that is designed to curve upstream so that the force of the water against it, known as hydrostatic pressure, presses against the arch, compressing and strengthening the structure as it pushes...
on the Verzasca River
Verzasca River
-- The Verzasca is a 30-km long mountain river originating at Pizzo Barone and flowing into Lake Maggiore. It is known for its clear turquoise water and vibrant colored rocks, as well as its treacherous currents. The Verzasca Dam is a few kilometers upriver from this lake.-Geography:The Verzasca...
in the Val Verzasca
Valle Verzasca
The Valle Verzasca is a valley in the Locarno district of the Canton of Ticino, Switzerland. It comprises the municipalities of Mergoscia, Vogorno, Corippo, Lavertezzo, Brione, Gerra, Frasco and Sonogno with a total population of 3,200 . Mergoscia is at the geographical center of the Ticino, and...
of Ticino
Ticino
Canton Ticino or Ticino is the southernmost canton of Switzerland. Named after the Ticino river, it is the only canton in which Italian is the sole official language...
, Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
. The dam creates Lago di Vogorno
Lago di Vogorno
Lago di Vogorno is a lake near Tenero, in Ticino, Switzerland. The reservoir on the Verzasca river is formed by the Verzasca Dam, built 1961-1965. The water surface area is 1.68 km²....
2 km (1.2 mi) upstream of Lake Maggiore
Lake Maggiore
Lake Maggiore is a large lake located on the south side of the Alps. It is the second largest of Italy and largest of southern Switzerland. Lake Maggiore is the most westerly of the three great prealpine lakes of Italy, it extends for about 70 km between Locarno and Arona.The climate is mild...
and supports a 105 MW hydroelectric power station
Power station
A power station is an industrial facility for the generation of electric energy....
. It was constructed between 1961 and 1965 and starting shortly after its reservoir
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
was filled, a series of earthquakes related to its water load occurred until 1971. The dam is owned and operated by Verzasca SA and is the fourth tallest in Switzerland.
The dam became a popular bungee jumping
Bungee jumping
Bungee jumping is an activity that involves jumping from a tall structure while connected to a large elastic cord. The tall structure is usually a fixed object, such as a building, bridge or crane; but it is also possible to jump from a movable object, such as a hot-air-balloon or helicopter, that...
venue after a James Bond
James Bond
James Bond, code name 007, is a fictional character created in 1953 by writer Ian Fleming, who featured him in twelve novels and two short story collections. There have been a six other authors who wrote authorised Bond novels or novelizations after Fleming's death in 1964: Kingsley Amis,...
stuntman jumped off it in the opening scene of the 1995 film GoldenEye
GoldenEye
GoldenEye is the seventeenth spy film in the James Bond series, and the first to star Pierce Brosnan as the fictional MI6 agent James Bond. The film was directed by Martin Campbell and is the first film in the series not to take story elements from the works of novelist Ian Fleming...
; a stunt voted as the best movie stunt of all time in a 2002 Sky Movies
Sky Movies
Sky Movies is the collective name for the premium subscription television movie channels operated by Sky Television, and later British Sky Broadcasting. It has around 5 million subscribers, via satellite, cable and IPTV in the UK and Ireland...
poll.
Background
On May 6, 1960, Verzasca SA was formed to construct the dam as the center-piece of the Verzasca Hydroelectric Complex. Construction in the dam began in 1961. The dam was designed and its construction supervised by Lombardi & Gellaro Ltd. Because the Contra Dam is at a lower elevation compared to other Swiss dams, warmer weather allowed construction to be carried out year-round. To divert the river and prepare a dry work-site for the dam, cofferdamCofferdam
A cofferdam is a temporary enclosure built within, or in pairs across, a body of water and constructed to allow the enclosed area to be pumped out, creating a dry work environment for the major work to proceed...
s were constructed, one of which redirected the river through a diversion tunnel with a 200 m3/s capacity. As the river can have flows much higher than the tunnel's capacity, this was accepted as a risk by engineers. Excavation of the right side of the dam had to be expanded due to unforeseen weathered rock and designs were altered within 15 days.
Concrete pouring and placement occurred for 18 months, of which the maximum poured in a day was 3100 cubic metre and in a month, 55000 cubic metre. The aggregate
Construction Aggregate
Construction aggregate, or simply "aggregate", is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined material in the world...
for the concrete was obtained from a quarry near the construction site. The high-quality and strength gneiss
Gneiss
Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks.-Etymology:...
-rock was ground in a rotary crusher and prepared in the concrete mixture. To facilitate the contraction and settling of the concrete in the dam, it was cooled with a series of steel pipes that ran throughout the mass of concrete, with the exception of the top 30 m (98.4 ft) of the dam. A grout curtain
Grout curtain
Grout curtains are barriers that protect a dam from seepage and can be used in initial construction or repair. Additionally, they can be used to strengthen foundations and contain spills.-Characteristics:...
was placed around and below the dam as well to prevent leakage, which consumed a large amount of cement. In August 1964, the reservoir began to fill and in September 1965, the reservoir was full and the dam completed.
Seismic activity
During what Dr. Giovanni LombardiGiovanni Lombardi (engineer)
Giovanni Lombardi, is a Swiss engineer specialized in civil works and tunnel construction.In late 2006 his company Lombardi Engineering Ltd, a Swiss engineering and design company, was retained to build the...
, the dam's designer, described as an "exceptionally rapid rise of water during the first filling" of the reservoir, beginning in August 1964, there were seismic shocks. The earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
s began in May 1965 and the biggest shocks had occurred later in October and November after the reservoir was full. The epicenters were located at two faults near the dam. As many as 25 shocks occurred a day. The shocks stopped once the reservoir was emptied and no damage was found. After refilling, the shocks decreased and an "equilibrium" was believed to have been reached, one that did not respond to variations in water load. Another large shock occurred several years after filling. By 1971, there were no more seismic shocks around the dam or reservoir. No known detailed geological studies were conducted prior to construction of the dam and several faults are known to exist in the area.
Dam
The Contra Dam is a concreteConcrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
slender arch dam
Arch dam
An arch dam is a type of dam that is curved and commonly built with concrete. The arch dam is a structure that is designed to curve upstream so that the force of the water against it, known as hydrostatic pressure, presses against the arch, compressing and strengthening the structure as it pushes...
with a height of 220 m (721.8 ft) and crest length of
380 m (1,246.7 ft). The dam is 25 m (82 ft) wide at its base and 7 m (23 ft) wide at its crest. The dam structure contains 660000 cubic metre of concrete and the structure itself has a surface area of 44500 square metre. The dam is slender in design and its horizontal arches are in an elliptical shape. The horizontal curvature of the dam decreases from the center of the dam towards its abutments and the curvature from the center of the arches increases from the crest down to the foundation. The thickness is constant with the exception of where the dam is received by its abutments; here it is thicker to reduce pressure on the rock. The strong rock can accept stresses of 70 kg/cm2. Vertically, the thickness of the dam increases from the crest down to the foundation and has a slight curve from the center towards the crest. This helps alleviate tensile stress for when the reservoir is not only full but empty. The dam's outlet works
Outlet works
A set of outlet works is a device used to release and regulate water flow from a dam. Such devices usually consist of one or more pipes or tunnels through the embankment of the dam, directing water usually under high pressure to the river downstream...
consist of two discharge pipes, capable releasing up to 170 m3/s each. One discharges into the original diversion tunnel and another is located at the base of the dam and discharges into the river valley below.
The dam creates Lago di Vogorno
Lago di Vogorno
Lago di Vogorno is a lake near Tenero, in Ticino, Switzerland. The reservoir on the Verzasca river is formed by the Verzasca Dam, built 1961-1965. The water surface area is 1.68 km²....
which has a 105000000 cubic metre capacity and surface area of 160 ha (395.4 acre), collected from a catchment area of 230 km² (88.8 sq mi). The Verzasca River has very irregular seasonal flows which can reach as high as 1000 m3/s.
Dr. Lombardi considers it one of his most aesthetically pleasing dams, primarily because of the slenderness of the concrete arch and the "outstanding cleanness of the design." The design also reduced the amount of concrete needed, therefore reducing the cost as well.
Spillways
The dam has two spillwaySpillway
A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...
s, each located on the structure, near its abutments on either side which have a maximum discharge capacity of 1300 m3/s. Each spillway contains six fixed-crest weir
Weir
A weir is a small overflow dam used to alter the flow characteristics of a river or stream. In most cases weirs take the form of a barrier across the river that causes water to pool behind the structure , but allows water to flow over the top...
s that are 12 m (39.4 ft) wide. From each opening, the water flows down a single chute to a flip bucket at the bottom of the spillway. The flip buckets dissipate and deflect the water towards the center axis of the valley 200 m (656.2 ft) below. The spillways were later modified to improve releases and function by increasing the size of the piers and adding additional lateral deflectors near the crest.
Power plant
The dam supports a 105 MW power stationPower station
A power station is an industrial facility for the generation of electric energy....
that contains 3 x 35 MW Francis turbine
Francis turbine
The Francis turbine is a type of water turbine that was developed by James B. Francis in Lowell, Massachusetts. It is an inward-flow reaction turbine that combines radial and axial flow concepts....
s and generates and average of 234 GWh annually. Water from the reservoir at 470 m (1,542 ft) above sea level is transferred to an underground power station
Underground power station
An underground power station is a type of hydroelectric power station constructed by excavating the major components from rock, rather than the more common surface-based construction methods....
downstream at 193 m (633.2 ft) above sea level, affording a maximum hydraulic head
Hydraulic head
Hydraulic head or piezometric head is a specific measurement of water pressure above a geodetic datum. It is usually measured as a water surface elevation, expressed in units of length, at the entrance of a piezometer...
of 277 m (908.8 ft). The power plant can discharge up to 50 m3/s of water which exits via a 1.9 km (1.2 mi) tailrace tunnel into Lago di Verbano. The builder and owner is Verzasca SA has an 80-year concession on the power station which will expire in 2046.
Popular culture
The opening scene of the 1995 James BondJames Bond
James Bond, code name 007, is a fictional character created in 1953 by writer Ian Fleming, who featured him in twelve novels and two short story collections. There have been a six other authors who wrote authorised Bond novels or novelizations after Fleming's death in 1964: Kingsley Amis,...
film GoldenEye
GoldenEye
GoldenEye is the seventeenth spy film in the James Bond series, and the first to star Pierce Brosnan as the fictional MI6 agent James Bond. The film was directed by Martin Campbell and is the first film in the series not to take story elements from the works of novelist Ian Fleming...
featured Bond jumping off the dam. The stunt was performed by British stuntman
Stuntman
A stuntman or stunt performer is someone who performs dangerous stunts.Stuntman may also refer to:*The Stunt Man, a 1980 film starring Peter O'Toole*Stuntman , a 2002 video game**Stuntman: Ignition, its sequel...
Wayne Michaels. The jump was voted as best movie stunt of all time in a 2002 Sky Movies
Sky Movies
Sky Movies is the collective name for the premium subscription television movie channels operated by Sky Television, and later British Sky Broadcasting. It has around 5 million subscribers, via satellite, cable and IPTV in the UK and Ireland...
poll. The dam doubled as the fictional Arkhangelsk
Arkhangelsk
Arkhangelsk , formerly known as Archangel in English, is a city and the administrative center of Arkhangelsk Oblast, Russia. It lies on both banks of the Northern Dvina River near its exit into the White Sea in the north of European Russia. The city spreads for over along the banks of the river...
Chemical Weapons Facility located in the northern Soviet Union during the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
.
Contestants bungee jumped off the dam as a Roadblock task in the first episode of the 14th season
The Amazing Race 14
The Amazing Race 14 is the fourteenth installment of the reality television show The Amazing Race. The Amazing Race 14 featured 11 teams of two, with a pre-existing relationship, in a race around the world....
of The Amazing Race
The Amazing Race
The Amazing Race is a reality television game show in which teams of two people, who have some form of a preexisting personal relationship, race around the world in competition with other teams...
.
The dam owners started to lease access to the dam, soon after GoldenEye was released, to a commercial bungee jump
Bungee jumping
Bungee jumping is an activity that involves jumping from a tall structure while connected to a large elastic cord. The tall structure is usually a fixed object, such as a building, bridge or crane; but it is also possible to jump from a movable object, such as a hot-air-balloon or helicopter, that...
operator. According to the operator, over 10,000 people have jumped the 220 m (720 ft) from the dam.
External links
- Dam profile - Swiss Committee on Dams
- Bungee jumping at the dam (photographs and video)
- Trekking-Team, bungy operator at the dam
- Intrepid Earth Verzasca Dam