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50-561: The Chirkey Dam (Chirkeisk GES) is an arch dam on the Sulak River in Dagestan , Russia . The main purpose of the dam is hydroelectric power production, and it supports a 1,000 MW power station. Construction on the dam began in 1964, the first generator was operational by 1974, the last in 1976 while the project was officially completed in 1978. It is the tallest arch dam in Russia. The dam

100-403: A flat rocky bed of 75 feet (23 m) width was available to lay the foundation for the arch dam without resorting to large-scale excavations. The dip of the rock was also steep both on upstream and downstream side of the flat base. Bank to bank, the crest length is 640 feet (200 m). The dam envisaged storage of about 18,000 acre-feet (22,000,000 m ) at the full reservoir level while it

150-471: A new power plant was built adjoining the old powerhouse, with installation of 6.7 MW capacity. Even though the project was initially built for hydroelectric power generation to meet the mining requirements, it has over the years evolved into a multipurpose reservoir with benefits of power generation, drinking water and fisheries. The rehabilitated dam and the new power house facility at the lower house site are now fully functional. The generating capacity of

200-479: A radius of 35 m (115 ft). Their second dam was built around 1350 and is called the Kurit Dam . After 4 m (13 ft) was added to the dam in 1850, it became 64 m (210 ft) tall and remained the tallest dam in the world until the early 20th century. The Kurit Dam was of masonry design and built in a very narrow canyon. The canyon was so narrow that its crest length is only 44% of its height. The dam

250-413: A surface area of 42.4 km (16 sq mi), length of 40 km (25 mi) and maximum width of 5 km (3 mi). Maximum depth of the reservoir is 200 m (656 ft) and its catchment area is 11,290 km (4,359 sq mi). The dam's spillway consists of a 509 m (1,670 ft) long non-pressure tunnel with its intake on the left bank of the dam. The spillway's capacity

300-594: Is double-curved in both its horizontal and vertical planes may be called a dome dam . Arch dams with more than one contiguous arch or plane are described as multiple-arch dams . Early examples include the Roman Esparragalejo Dam with later examples such as the Daniel-Johnson Dam (1968) and Itaipu Dam (1982). However, as a result of the failure of the Gleno Dam shortly after it was constructed in 1923,

350-411: Is 2,900 m/s (102,413 cu ft/s). The dam's outlet works , spillway and power station have a combined discharge capacity of 3,550 m/s (125,367 cu ft/s). The dam's power station contains 4 × 250 MW Francis turbine -generators for a total installed capacity of 1,000 MW. Each generator is supplied with water by a penstock , all four of which intake on the upstream side of

400-495: Is 214 meters (702 ft) high and 1,314 meters (4,311 ft) long across its crest. It was completed in 1968 and put in service in 1970. Pensacola Dam was one of the last multiple arch types built in the United States. Its NRHP application states that this was because three dams of this type failed: (1) Gem Lake Dam, St. Francis Dam (California), Lake Hodges Dam (California). None of these failures were inherently caused by

450-573: Is 30 feet (9.1 m) and depth of water is about 1.5 feet (0.46 m). The basin is surrounded by hills with steep slopes and with elevation above 980 feet (300 m) above sea level. The distance from the dam to Juneau city is 2.9 miles (4.7 km), to the Juneau harbor is 3.2 miles (5.1 km), and to the Juneau Harbor Seaplane Base is 3.4 miles (5.5 km). During the Roman period ,

500-484: Is 445 acre-feet (549,000 m ) when the water is 25 feet (7.6 m) deep. A steel outlet pipe of 4 feet (1.2 m) diameter was proposed to be embedded in the mid base of the dam as a spillway . The dam was planned with a top elevation of 343 feet (105 m) above sea level. The reservoir water spreads to an area of 192 acres (78 ha), while the catchment drained is 7.5 square miles (19 km ). Concurrently, two power houses were planned to generate power for

550-440: Is a 232.5 m (763 ft) tall and 338 m (1,109 ft) long (crest) concrete arch dam. It is 6 m (20 ft) wide at its crest, 30 m (98 ft) wide at its base and contains 1,275,000 m (45,026,200 cu ft) of concrete . The dam withholds a 2,780,000,000 m (2,253,783 acre⋅ft) reservoir of which 1,320,000,000 m (1,070,141 acre⋅ft) is active or "useful" storage. The reservoir has

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600-403: Is made of concrete and placed in a V-shaped valley. The foundation or abutments for an arch dam must be very stable and proportionate to the concrete. There are two basic designs for an arch dam: constant-radius dams , which have constant radius of curvature, and variable-radius dams , which have both upstream and downstream curves that systematically decrease in radius below the crest. A dam that

650-545: Is still erect, even though part of its lower downstream face fell off. The Tibi Dam in Tibi , Spain was a post-medieval arch dam built between 1579 and 1594 and the first in Europe since the Romans. The dam was 42.7 metres (140 ft) high and 65 metres (213 ft) long. This arch dam rests on the mountains sides. In the early 20th century, the world's first variable-radius arch dam

700-507: Is supplied to the city. However, this source is subject to seasonal high turbidity and also interruptions due to the annual maintenance of the generator units. This system is able to supply 2,000,000 US gallons (7,600 m ) of water. The water resources are generally pollution-free and quality is monitored and tested every month to check for drinking-water standards set by the EPA and Alaska Department of Environmental Conservation (ADEC). In 1880,

750-634: The Gastineau Channel . The dam (marked as Juneau B-2 in USGS maps) is located at the terminus of the tram-way that was built specifically by the Alaska Gastineau Mining Co. The tram-way was built for hauling material for constructing the dam and its associated power stations. The power supply was for the mines located at a site 6 miles (9.7 km) to the south at Sheep Creek . However, a 3 miles (4.8 km) long road had been built by AEL&P to

800-575: The 143-meter double-curved Morrow Point Dam in Colorado, completed in 1968. By the late 20th century, arch dam design reached a relative uniformity in design around the world. Currently, the tallest arch dam in the world is the 305 metres (1,001 ft) Jingpin-I Dam in China , which was completed in 2013. The longest multiple arch with buttress dam in the world is the Daniel-Johnson Dam in Quebec , Canada . It

850-547: The Salmon Creek was named by Richard Harris and Joe Juneau (during their first visit to the area for gold prospecting). The local people called it Tilhini meaning "dog salmon" a native name used by Tingit Alaskan Indian ; this name is also shown in some early topographic maps. In 1917, fish propagation was established in Salmon Creek Reservoir by introducing 50,000 fry lings (small and young recently hatched fish) in

900-470: The arch radius increases from the base to the crest; this increase towards the crest is proportional to the increase of the canyon width of the gorge. Further, according to the theory of constant-arch design, the arch action at the base of the dam exerts the maximum pressure on the base. A V-shaped gorge in particular is considered an ideal feature for building this type of dam. This design ensures substantial savings in use of construction material as opposed to

950-456: The base to 331 feet (101 m) at the crest. The "V" shape of the gorge at the dam site was adjudged ideal for building this type of dam at Salmon Creek site. An ice pressure of 10 tons per square foot (500 kPa) was considered based on the rim conditions of the reservoir and the design was also checked for an ice pressure of 20 tons per square foot (1,000 kPa); in the latter case the safety factor in concrete under resultant compression values

1000-403: The constant–radius arch and the constant-angle arch, the latter design is more complex. In the constant-radius arch design, which is also known as the single-radius arch, the shape of the dam is cylindrical with vertical upstream face while the downstream face is battered . The constant-angle arch design has also a variable–radius arch. In this design, the central opening angle is constant whereas

1050-466: The constant–radius arch design. Lars R. Jorgenson who had conceived this concept had proved that the most economic design of the dam was obtained with an optimum opening angle of 133.6°, with the least quantity of concrete. This design was applied with some modifications for the Salmon Creek Dam, which was designed with constant opening angle of 113° with radius varying from 147.5 feet (45.0 m) at

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1100-448: The construction of new multiple arch dams has become less popular. Contraction joints are normally placed every 20 m in the arch dam and are later filled with grout after the control cools and cures. Salmon Creek Dam The Salmon Creek Dam is a concrete arch dam on the Salmon Creek, 3 miles (5 km) northwest of Juneau , Alaska . Built in 1914, it is the world's first constant-angle arch variable radius dam. Since it

1150-427: The cost of construction. Basically, an arch dam is a structure that curves upstream and the water pressure is transferred either directly to the valley sides or indirectly through concrete abutments. Theoretically, the ideal constant angle arch in a V-shaped valley for such an arch dam has a central angle of 133° of curvature. This theory led to the development of the "constant-angle" (or variable radius) arch dam, which

1200-407: The crushing plant. The aggregates were mixed in designed proportions with cement and with a small admixture of lime to manufacture concrete for placing on the dam. The first batch of concrete was placed on the dam on July 14, 1913. The dam was completed, over a 13 months period, on August 13, 1914. A concrete quantity of 54,000 cubic yards (41,000 m ) was placed on the dam. Concrete was placed at

1250-468: The dam also needed to be rehabilitated and work was carried out in 1967. Deteriorated concrete was removed, the dam body was regrouted and the upstream face of the dam was provided with a layer of high strength concrete in the top 45 feet (14 m). The lower power house also underwent major rehabilitation measures. It was shut down in December 1974 due to the high cost of operation and maintenance. In 1984

1300-415: The dam has a clear span of 60 ft (18 m) and each buttress is 24 ft (7.3 m) wide. Arch dam designs would continue to test new limits and designs such as the double- and multiple-curve. Alfred Stucky and the U.S. Bureau of Reclamation developed a method of weight and stress distribution in the 1960s, and arch dam construction in the United States would see its last surge then with dams like

1350-511: The dam's face and run down its surface toward the power station at the dam's base. Arch dam In general, arch dams are classified based on the ratio of the base thickness to the structural height (b/h) as: Arch dams classified with respect to their structural height are: The development of arch dams throughout history began with the Romans in the 1st century BC and after several designs and techniques were developed, relative uniformity

1400-412: The drinking water sources to Juneau city and for aquaculture and fishing. When built, adoption of the constant arch design for the dam reduced costs by 20% because less concrete was needed to construct the dam. Of the two hydroelectric power stations built at the initial stage (one at the upper level and the other at the lower level) – the latter one is still in use after a new powerhouse was built adjoining

1450-413: The following: The upstream bulging served to offset the undercutting by the stronger curved lower arches near the abutments while the pronounced downstream toe reduced the tensile stresses at the upstream heel. The full realization of the new design was made possible by building the dam entirely out of concrete. Based on the plans prepared for the concrete arch dam and the two power stations, construction

1500-522: The historian Procopius would write of its design: "This barrier was not built in a straight line, but was bent into the shape of a crescent, so that the curve, by lying against the current of the river, might be able to offer still more resistance to the force of the stream." The Mongols also built arch dams in modern-day Iran. Their earliest was the Kebar Dam built around 1300, which was 26 m (85 ft) high and 55 m (180 ft) long, and had

1550-581: The mining industry from the reservoir's water – an upper power station with a 3 MW capacity about 1 mile (1.6 km) downstream of the dam and a lower power station with a 3 MW capacity near the shore of the Gastineau Channel. The variable-radius type shape of the dam adopted for Salmon Creek became a standard for many high and large dams, particularly in western USA. An article from the National Science Foundation's SimScience project notes

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1600-401: The multiple arch design. The design of an arch dam is a very complex process. It starts with an initial dam layout, that is continually improved until the design objectives are achieved within the design criteria. The main loads for which an arch dam is designed are: Other miscellaneous loads that affect a dam include: ice and silt loads, and uplift pressure. Most often, the arch dam

1650-520: The old one – it produces 10% of the energy needs of Juneau city. When built, the dam and its two power plants were considered engineering wonders. Both are operated and maintained by the Alaska Electric Light & Power (AEL&P). The dam was built in a forested, scenic and narrow valley of the Salmon creek, which runs from Salmon Creek Reservoir and flows southwest for 3 miles (4.8 km) to

1700-485: The power station are then pumped to a water treatment plant for membrane filtration, chlorination, and pH and alkalinity adjustment with soda ash before the water is supplied to the distribution system. This system was commissioned by the City Borough of Juneau (CBJ) in 2015. The reservoir is also used as chlorine contact tanks, where chlorine is added for purification and given time to react with any pathogens , before it

1750-435: The power station is 29.5 GWh annually, which accounts for nearly 10% of Juneau's power demand. Alaska Electric Light and Power operates and maintains the system. Salmon Creek reservoir is a secondary source of drinking water which is provided in conjunction with Alaska Electric Light and Power Company (AEL&P). Water is drawn from near the Salmon Creek power generation plant, which is located near sea level. Tail waters from

1800-450: The rate of 400 cubic yards (310 m ) per day. Between 1912 and 1914, two power stations were built to utilize the water stored in the reservoir created by the dam. The first power station, the upper powerhouse titled 'Powerhouse 2', was located 1 mile (1.6 km) below the dam and had an installation of two units of 1.5 MW capacity each operating under a hydraulic head of 600 feet (180 m). The tail waters from this power station

1850-485: The specific first design of the constant arch dam. However, AEL&P gives design credit to their then Chief Engineer Harry L. Wallenberg for the Salmon Creek Dam. The idea for building such a dam had been thought about 30 years earlier to economize on the use of construction material for building the dam. However, it was only in 1913 that the concept was transformed on ground by the pioneer mining engineer Thane. In arch dam design, two basic shapes are adopted. These are

1900-459: The state of Oklahoma in 1940, was considered the longest multiple arch dam in the United States. Designed by W. R. Holway , it has 51 arches. and a maximum height of 150 ft (46 m) above the river bed. The total length of the dam and its sections is 6,565 ft (2,001 m) while the multiple-arch section is 4,284 ft (1,306 m) long and its combination with the spillway sections measure 5,145 ft (1,568 m). Each arch in

1950-445: The theory of building a curved dam (arch dam) was known as a means to withstand the water pressure and hold the masonry joints. However, in the background of masonry arch dams which dominated dam building scenario in the 19th century and with introduction of concrete technology for building dams, the structural design of arch dams underwent a dramatic change in its economic evolution to minimize use of construction material and inter alia,

2000-428: The two power stations was 5,187 horsepower (3,868 kW). Near Powerhouse 1 on the shore, office buildings, machine shops, saw mills, canteen and housing facilities for staff were also built. Since its completion, the dam and its two power stations have gone through many rehabilitation measures. Power House 2 was damaged in a fire in 1923. It was rehabilitated in 1935. It was finally abandoned in 1998. With aging,

2050-408: The upper powerhouse at the base of the Salmon Creek Dam, which has since been de-commissioned. The creek runs for a length of 3 miles (4.8 km) within the watershed, which has a creek divide of 1.5 miles (2.4 km) and a ridge line of 2.2 miles (3.5 km). The stream bed has large gravel and bedrock substrata and its gradient decreases downstream of the dam. The average width of the stream

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2100-598: The world, in particular by the U.S. Bureau of Reclamation . In 1920, the Swiss engineer and dam designer Alfred Stucky developed new calculation methods for arch dams, introducing the concept of elasticity during the construction of the Montsalvens arch dam in Switzerland, thereby improving the dam profile in the vertical direction by using a parabolic arch shape instead of a circular arch shape. Pensacola Dam , completed in

2150-657: Was achieved in the 20th century. The first known arch dam, the Glanum Dam , also known as the Vallon de Baume Dam, was built by the Romans in France and it dates back to the 1st century BC. The dam was about 12 metres (39 ft) high and 18 metres (59 ft) in length. Its radius was about 14 m (46 ft), and it consisted of two masonry walls. The Romans built it to supply nearby Glanum with water. The Monte Novo Dam in Portugal

2200-671: Was also thinner in design. The theory was first initiated in North America for several dams, and in Alaska in particular, in 1913 with the building of the Salmon Creek Dam, which was completed in 1914. In this regard, Bartlett Lee Thane , the mining engineer, who made a lasting impact in the mining industry – in the Alaska-Gastineau Mining Company – was instrumental in introducing this design of thin arch dam with help from his former football team mates. Lars Jorgensen evolved

2250-404: Was another early arch dam built by the Romans in 300 AD. It was 5.7 metres (19 ft) high and 52 m long (171 ft), with a radius of 19 m (62 ft). The curved ends of the dam met with two winged walls that were later supported by two buttresses. The dam also contained two water outlets to drive mills downstream. The Dara Dam was another arch dam built by the Romans in which

2300-556: Was built on the Salmon Creek near Juneau , Alaska . The Salmon Creek Dam's upstream face bulged upstream, which relieved pressure on the stronger, curved lower arches near the abutments. The dam also had a larger toe, which off-set pressure on the upstream heel of the dam, which now curved more downstream. The technology and economical benefits of the Salmon Creek Dam allowed for larger and taller dam designs. The dam was, therefore, revolutionary, and similar designs were soon adopted around

2350-464: Was built, over 100 such dams have been constructed all over the world. The dam was designated as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers in 2022. The dam was built by the Alaska-Gastineau Mining Company to meet the electrical energy needs for mining operations. The dam continues to be fully functional for hydroelectric generation, as one of

2400-406: Was considered to be 5 and safe. The dam was designed with a base width of 47.5 feet (14.5 m) (width of 37.5 feet (11.4 m) is also mentioned in one source) and it tapers to a width of 6.5 feet (2.0 m) (6 feet (1.8 m) is also mentioned in one source ) at the top over a dam height of 168 feet (51 m). The geological condition at the base of the dam also dictated the type of dam as

2450-409: Was conveyed through a 10,000 feet (3,000 m) long power channel to the second power station titled 'Powerhouse 1' located on the shore of the Gastineau Channel. The power house at this location also had two units of 1.5 MW capacity each operating under a head of 500 feet (150 m). Thus, the total generation from the two power stations was 6,000 kW (8,000 hp). In 1916, the average load on

2500-559: Was started in May 1912. Construction of the lower power house on the shore at the confluence of Salmon Creek with Gastineau Channel was initiated first; a transmission line was erected from here to the mines in March 1913 and the construction of the dam was started in April 1913. Construction facilities for the dam were established upstream where aggregates (fine and coarse) were produced by crushing rocks at

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