The Alto Maipo hydroelectric project is located in San Jose de Maipo, Chile; and more than 90% of the works are developed underground and concentrated in the valleys of Volcan, Yeso, Colorado and Maipo river.
The project, which began in December 2013, includes two run-of-river power plants: Alfalfal II and Las Lajas, arranged in hydraulic series, for which 67 km of tunnel will be built between the high sector of the Volcan River and Las Lajas in the Maipo River.
The works include five water intakes; the aforementioned tunnels, at an average depth of 800 meters; two underground powerhouses (Alfalfal II and Las Lajas) with a combined generating capacity of 531 MW (264 MW Alfalfal II and 267 MW Las Lajas); and only 17 km of high voltage lines. Since surface works required to build and operate the project are only 10% of the total of works, the impact on the landscape, flora and fauna is very limited.
It is important to note that during the operation of Alto Maipo, the ecological flow of the watercourses will not be affected, neither the economic nor the recreational activities that take place around the Maipo river (fishing, rafting, kayaking, etc.).
In addition, the turbine water for power generation will be discharged to the Maipo river watercourse 6 km before the water treatment plant located in Las Vizcachas, so it will not interfere with the supply of drinking water to the city of Santiago.