| El Cajón Dam | |
|---|---|
| Official name | Central Hidroeléctrica Francisco Morazán |
| Location | Cortés, Honduras |
| Coordinates | |
| Construction began | 1980 |
| Opening date | 1985 |
| Construction cost | US$775 million[1] |
| Dam and spillways | |
| Height | 226 m (741 ft) |
| Length | 282 m (925 ft) |
| Base width | 48 m (157 ft) |
| Impounds | Comayagua River |
| Reservoir | |
| Capacity | 5,700,000,000 m3 (2.0×1011 cu ft) |
| Surface area | 94 km2 (36 sq mi) |
| Power station | |
| Turbines | 4 × 75MW |
| Installed capacity | 300 MW |
| Bridge | |
| Width | 7 m (23 ft) |
The El Cajón Dam, officially known as Central Hidroeléctrica Francisco Morazán, is a hydroelectric power plant located in Western Honduras.[2] The dam impounds the Comayagua river which derives its large volume from two large tributaries, Humuya and Sulaco. 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, 16th highest in the world. El Cajón is also the highest arch dam in the western hemisphere, and the sixth highest arch dam worldwide.
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El Cajón 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.
Harza Engineering of Chicago, Illinois, USA, 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, Switzerland, and Panama. Panamanian and Italian companies were responsible for the construction of the 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.
Finite element design was used for the structural components of the dam. The dam is 282 meters long, and 48 meters thick at bottom.[3] 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.[3] Near the top of the dam is a spillway composed of four large square tubes each 14 meters wide that are opened when flow through the dam cannot be handled by the lower discharge tubes.
The reservoir created by El Cajón spans 94 km² with a maximum capacity of around 5,700 million m³.[3] The reservoir displaced approximately 4,700 people.[4] 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.[3]
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 230kV.
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 an 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.