Alto Maipo

completed

The Project comprises the construction of two run-of-the-river hydroelectric facilities connected in series with a combined capacity of 531 MW for the purposes of providing baseload electricity to the Chilean Central Inteconnected Grid or SIC. The Project will be developed in the Upper Volcan River, Upper Yeso River and Colorado River, all in the Maipo River Basin and 90% of the Project’s infrastructure will be underground. Underground facilities will include powerhouses, siphons, access tunnels and water conveyance systems, including a total of 67 kilometers (km) of tunnels. The Project does not require the construction of surface water reservoirs. Surface infrastructure will include intakes, delivery canals, forebay structures, a new electrical substation, new bridges, access roads and 17 km of transmission lines. The total permanent surface infrastructure will occupy 85 hectare (ha) (with additional 20 has of temporary facilities) and 61.25 ha for the transmission line. Current land use of areas that will be used by the Project’s above-ground infrastructure includes agriculture, cattle grazing and unimproved areas. The underground facilities traverse two protected areas at several hundreds of meters of depth, (a Nature Sanctuary and a Natural Monument) although no surface works are foreseen in any of these protected areas. During the construction phase, 14 muck deposits, ranging in size from 0.83 ha to 5.61 ha, will be sited throughout the Project area and, generally in close proximity to the tunnel portals. The Maipo, Colorado, Volcán, and Yeso rivers are highly intervened by historic and current activities which include limestone mining, other run-of-river power projects (some dating back to the 1920s), informal extraction of riverbed sediments for construction materials, construction of a water reservoir, used today for drinking water supply and irrigation, and introduction of fish species for recreational purposes. The PHAM project will contribute to the production of renewable energy for the Chilean central grid system, off-setting the use of thermal power sources and the generation of approximately 1.5 million tons of CO2 emissions annually. Due to its proximity to the metropolitan region of Santiago, it will further contribute to the stability of electricity supply of the region.