El Cajón Dam (Honduras)

This article is about the dam in Honduras. For other dams named El Cajón, see El Cajón Dam.
El Cajón Dam
Location of El Cajón Dam in Honduras
Official name Central Hidroeléctrica Francisco Morazán
Location Cortés, Honduras
Coordinates 15°04′47″N 87°33′32″W / 15.07972°N 87.55889°W / 15.07972; -87.55889Coordinates: 15°04′47″N 87°33′32″W / 15.07972°N 87.55889°W / 15.07972; -87.55889
Construction began 1980
Opening date 1985
Construction cost US$775 million<ref "name=ASCE">{{Cite book|author=American Society of Civil Engineers. Hydropower Task Committee |title=Civil works for hydroelectric facilities|publisher=ASCE Publications |date=2007|url=https://books.google.com/books?id=BXc6OaAMz4UC&hl=en |pages=129–130 |isbn=978-0-7844-0923-7}}</ref>
Operator(s) ENEE
Dam and spillways
Impounds Comayagua River
Height 226 m (741 ft)
Length 282 m (925 ft)
Width (base) 48 m (157 ft)
Reservoir
Total capacity 5,700,000,000 m3 (2.0×1011 cu ft)
Surface area 94 km2 (36 sq mi)
Power station
Commission date 1986
Turbines 4 × 75 MW Francis-type
Installed capacity 300 MW

The El Cajón Dam, officially known as Central Hidroeléctrica Francisco Morazán, is a hydroelectric power plant located in Western Honduras.[1] The dam impounds the Comayagua River, which derives its large volume from two large tributaries, the Humuya River and the Sulaco River. El Cajón is a double arch dam, which uses parabolic geometry in horizontal and vertical axises to spread the weight of the impounded water to canyon walls which act as buttresses. Overall, the dam is the fifth highest dam in the Americas and the 16th highest in the world, as well as the highest arch dam in the western hemisphere, and the sixth highest worldwide.

Location

El Cajón Dam is located 180 km (112 mi) from Tegucigalpa, the country's capital, and 80 km (50 mi) from San Pedro Sula, the main Honduran industrial city.

Construction

Harza Engineering of Chicago, Illinois, United States, began site investigation in the 1960s with initial construction beginning June 15, 1980. A multinational team of designers, builders and engineers included members from Italy, Germany, and Switzerland. Engineering design was developed by Motor Columbus [now Colenco] of Switzerland. Italian companies were responsible for the construction of the underground machine room, while Italian and German companies were responsible for dam construction and ancillary works. Upon completion the dam became the largest piece of infrastructure in Honduras, requiring over half a million cubic meters of concrete to construct. Due to its double-curved arch design, this dam is relatively thin compared to say, Hoover Dam (gravity dam design) that spans a similar valley profile yet required roughly four times as much concrete.

Design

Finite element design was used for the structural components of the dam. The dam is 282 metres long, and 48 meters thick at bottom.[2] The top is 7 meters thick which is wide enough for the small service road that crosses the dam. Around 170 meters from the base of the dam, three 14.5m2 discharge tubes expel water that has passed through the machine room's turbines.[2] Near the top of the dam is a spillway composed of four large square tubes each 14 metres wide that are opened when flow through the dam cannot be handled by the lower discharge tubes.

Reservoir

El Cajón Dam bridge
Characteristics
Width 7 m (23 ft)

The reservoir created by El Cajón spans 94 km² with a maximum capacity of around 5,700 million m³.[2] The reservoir displaced approximately 4,700 people.[3] While the main purpose of the reservoir is for powering El Cajón's turbines, flood control is another major benefit. Before completion of the dam, yearly flooding in the Sula valley seriously disrupted commerce for the people of Honduras. Now during the rainy season the reservoir has the ability to retain a layer of water ten meters high, and then discharge it slowly to prevent disastrous flooding. Agriculture has also benefited. Historically, during the dry season the Comayagua's flow dropped significantly to around 20 m3, the dam now provides year round flow of approximately 100 m3, which has had a significant economic impact for the region.[2]

Power Output

Eight large vertical axis turbines are located in a subterranean housing stationed in the left side of the limestone valley. Construction was done in two stages. Initially, four turbines were installed in the room; which at the time was already fairly large: 110 m long, 30 m wide, and 49 m high. The second stage of construction extended the length another 65 meters to house the remaining four turbines. Each turbine rotates at 300 R.P.M, powering its own generator capable of producing 75 megawatts. The completion of the second stage brought the total power output to 600 megawatts. The power produced there is then transmitted to a central station at 230 kV.

Instrumentation

Initially, electrical monitoring devices commonly used in modern dams were installed, but due to high sulphur content in the surrounding rock and water, all of the devices corroded and failed. With the exception of portable monitoring equipment, El Cajón now relies entirely on mechanical devices to check its performance.

The important role these devices play came into focus after a 7.1 magnitude earthquake, originating 200 miles north of Tegucigalpa, caused massive damage to many pieces of infrastructure May 28, 2009. These devices were critical to determining the internal deformation of the structure.

Notes

  1. ↑ "El Cajon Power Project". Worldbank. Retrieved 2009-10-05.
  2. 1 2 3 4 "Represa Hidroeléctrica Francisco Morazán "El Cajón"". ENEE. Retrieved 2009-10-05.
  3. ↑ McCully, 1996: 324-325

References

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