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Alto Maipo – Early Disclosure


Through this Early Disclosure, IFC provides access, early in the environmental and social assessment process, to this draft Environmental and Social Impact Assessment (ESIA). This ESIA has been prepared by the client and should not be taken as an indication that IFC has completed its review of the potential investment. The purpose of this Early Disclosure is to enhance the transparency of IFC’s activities with reference to those projects or investments with potential significant adverse environmental and social risks and/or impacts. Any project documentation or data included or attached herein has been prepared and authorized for public release by the client.


The disclosure of this ESIA should not be construed as presuming the outcome of IFC’s review of the potential investment or the decision of its Board of Directors. An updated version of the ESIA reviewed by IFC may be disclosed at a later stage. In addition, prior to any consideration of the investment by IFC’s Board of Directors, the Summary of Investment Information (SII) and the Environmental and Social Review Summary (ESRS) would be disclosed at least 60 days in advance.


Project number 31362 Early disclosure date May 30, 2012
Company name AES Gener Projected board date  October 1, 2012
Country Chile    
Sector V-BA - Large Hydro - Renewable Energy Generation           
Provisional Environmental Category A - Significant    
Department CN2S7 - Reg Ind, Infra & Nat Res, Caf/Cla/Infra-Pow Trans Util-CLA    
Region LAC    



Project description


The project under consideration involves the construction and operation of the 531 MW Alto Maipo hydropower project, which is composed of two separate hydropower plants known as Alfalfal II (264 MW) and Las Lajas (267 MW). The project has a total estimated cost of US$1.4 billion and an average output of 2,300 GWh per year.  Both hydropower plants are high-head, run-of-river plants in a hydraulic series located about 50 km east of Santiago, Chile. The project includes a 17 km-long transmission line. The project does not involve a reservoir or resettlement of population.  Construction of the plants will take place over a 4.5-5 year period and will require the drilling of about 67 km of tunnels (about 90% of total project civil works are expected to be underground).


Environmental Assessment Attachments


1. Alto Maipo Project: Repository of Environmental Assessment and Public Comments Documentation  – Chile’s Environmental Assessment Service  (Ficha del Proyecto Hidroeléctrico Reventazon Exp. N°105: Documentos de Evaluación Ambiental y Participación Ciudadana  – Servicio de Evaluación Ambiental, Gobierno de Chile)


2. Alto Maipo Project – Environmental Impact Assessment (Estudio de Impacto Ambiental), May 2008


3. Alto Maipo Project: EIA Addendum 1 (Adenda 1 EIA), January 2008


4. Alto Maipo Project: EIA Addendum 2 (Adenda 2 EIA), January 2009


5. Alto Maipo Project: EIA Addendum 3 (Adenda 3 EIA), March 2009


6. Alto Maipo Project: Environmental Qualification Resolution (Resolución de Calificación Ambiental – RCA), March 2009


7. Alto Maipo Project - Transmission Line: Environmental Impact Assesment (EIA Línea de Transmisión), September 2009


8. Alto Maipo Project - Transmission Line: Environmental Qualification Resolution (Resolución de Calificación Ambiental – RCA), July 2010


9. Alternatives Assessment (Analisis de Alternativas para el Proyecto - ) - Prepared by DAES Consultores for AES Gener - July 18, 2012

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10. Cumulative Impacts Assessment (Evaluacion de Impactos Acumulativos - Proyecto Hidroelectrico Alto Maipo) - Prepared by DAES Consultores for AES Gener - July 19, 2012

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