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Irrigation to Transform Desert Region of Peru

The Huancabama River has been redirected from the east side of the Andes Mountains to the west via a 20 km long tunnel
The Huancabama River has been redirected from the east side of the Andes Mountains to the west via a 20 km long tunnel. Odebrecht

A river is being diverted through the Andes in the hope of turning arid fields in western Peru into productive farmland.

May 21, 2013—The arid western Peruvian valley that includes the city of Olmos is not a place often associated with agriculture. The area receives just enough rainfall each year to support a sparse vegetation of trees and shrubs that punctuate the landscape. But a revolutionary irrigation project is under way that many hope will transform the desert terrain into thriving farmland that will help boost the region’s economy.

A century in the making, the Olmos Irrigation Project will divert the Huancabamba River from the eastern side of the Andes, from which it flows to the Amazon, to the western side, from which it will flow to the Olmos plains in the Lambayeque region of northwestern Peru. In 1902 an explorer by the name of Manuel Mesones Muro conceived the idea of redirecting the river to irrigate Olmos, and in 1924 Charles Sutton, an American engineer, proposed constructing a 20 km tunnel through the Andes to change the river’s course. Without sufficient funding, the project advanced slowly in the decades that followed; just 6 km of the tunnel had been excavated by 1985. But in 2004 the Peruvian government formed a public-private partnership with Odebrecht, an international engineering and construction firm headquartered in Brazil, and the final stage of construction finally commenced.

Odebrecht and its subsidiary companies were granted concessions to construct the Limón Dam in San Felipe district in the Jaén Province, one of 13 provinces in the Cajamarca region, as well as the remainder of the Andean tunnel and the subsequent irrigation infrastructure. The rock-filled embankment dam marks the beginning of the project; from there water will be diverted from the Atlantic basin of the Huancabamba River through the tunnel and to the Pacific basin. The entrance of the tunnel is nearly 14 m higher than the exit, so the water will be delivered by gravity. H2Olmos, a subsidiary of Odebrecht, will own, operate, and maintain the irrigation system, supplying water to 43,500 ha of what is expected to be highly profitable farmland. That includes 38,000 ha that have been divided into 50 lots and sold to private investors, many of whom will operate industrial farms, and 5,500 ha owned by local farmers who operate smaller farms. “The area has a dry tropical climate considered a natural greenhouse,” said Alfonso Pinillos, the director of H2Olmos, in written responses to Civil Engineering online. “With moderate temperatures, minimum rainfall, and no freeze, [it is] ideal for a variety of crops, including cotton, sugarcane, table grapes, avocados, mangoes, citrus, asparagus, peppers, and other vegetables with very high yields.” 

 Map of the Huancabama River which is diverted through the Andes Mountains and toward the Olmos plains

 The Huancabama River is being diverted through the Andes
Mountains and toward the Olmos plains in hopes of turning the
arid landscape into lush farmland. Odebrecht

The tunnel is 4.8 m in diameter and reaches a depth of 1,828.8 m, making it the second-deepest tunnel in the world, said Giovanni Palacios, an engineer and the project director for Odebrecht, in written responses to Civil Engineering online. Rugged terrain and complex geology comprising quartz porphyry, andesite, and tuff made excavation quite a challenge. A tunnel-boring machine manufactured by the Robbins Company, a firm based in Solon, Ohio, that specializes in advanced underground construction machinery, was deployed to excavate the tunnel on the west side, while traditional drilling and blasting methods were used to the east. According to a case study published by Robbins, the temperature in the tunnel exceeded 54°C, so a special ventilation and cooling system was attached to the tunnel-boring machine to cool the tunnel 32°C. The work was also complicated by the fact that the tunneling traversed more than 400 fault lines and that more than 16,000 rock bursts were recorded during the work. To contain the fractured rock, Robbins and Odebrecht installed a ground support system for the tunnel-boring machine and replaced the machine’s roof shield fingers with the McNally Support System, supplied by C&M McNally Engineering, of Toronto, which comprises steel slats anchored to the roof of the tunnel by steel straps and rock bolts, the case study says. Construction of “the trans-Andean tunnel has had a high degree of difficulty and probably has been the most difficult tunnel construction in the world,” Palacios said.

Ollanta Humala, Peru’s president, and Humberto Acuña, the president of the Lambayeque region, were on hand when the operators of the tunnel-boring machine completed excavation of the tunnel, in December 2011. Now the work for the irrigation portion of the project is under way, including construction of a second, 2 km tunnel in the coastal area near the Olmos plains. Drilling and blasting will be used for this tunnel, which will carry the water to the Palo Verde Reservoir; from there pressurized pipelines will deliver it to each of the agriculture lots. Construction of the second tunnel and related irrigation works are scheduled for completion by November 2014.

The tunnel component of the project was funded through a public-private partnership with a total investment of $247 million; the irrigation works component is being funded solely through private investment for a total of $280 million. In addition to investments by agribusiness firms and Odebrecht, bonds were issued on Lima’s stock exchange. The system is expected to transform the region’s arid land into productive agricultural assets with robust export operations. If successful, the project could lead to more than 40,000 direct jobs and more than 100,000 indirect jobs, Palacios said. The Olmos Irrigation Project is one of several irrigation projects planned for Peru’s west coast, but it is the only one that will be concluded in the near future. “The importance of their contribution to the Peruvian agribusiness industry is key, to consolidate nontraditional exports, increase the quality [of life] of the region[’s] population, and continue to generate skilled and nonskilled jobs,” Palacios said.



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