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Environmental and Social Impact Assessment

In order to fulfil all the environmental legal requirements of the Chilean government, the environmental impact assessment procedure, according to the 19300 Environmental General Basis Law (Ley 19.300 de Bases Generales del Medio Ambiente) and the Regulation on the Environmental Impact Assessment System (Reglamento del Sistema de Evaluación de Impacto Ambiental), was followed. This allowed us to obtain the environmental authorization to develop the Project, which included its construction phase until completion (closure).

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Thus, in 2012 the Environmental Qualification Resolution (Resolución de Calificación Ambiental, RCA) for the Transmission System of 500 KV Mejillones-Cardones Project was issued RCA 504/2012. Additionally, and as a result of modifications in the design of the project, the following complementary authorizations were obtained:

  • RCA 1044/2015: Modifications to the Layout of the Transmission System of 500 KV Mejillones-Cardones.
  • RCA 214/2015: Reinforcement for Mejillones.
  • RCA 114/2015: Reinforcement for Cardones.
  • RCA 181/2015: Connection of Cardones.
  • RCA 102/2016: Alternative Layout of Río Copiapó Area for the S. T. 500 KV Mejillones-Cardones Project.
  • RCA 130/2016: Alternative Layout of Río Salado Area for the 500 KV Mejillones-Cardones Transmission System Project.


The environmental authorizations of the Project (RCAs) have established a list of legal commitments, which are related to design considerations, construction methods, operation conditions, and environmental control and monitoring among others. These commitments can be classified related to the period of development at which they must be executed. Most of them are implemented during the construction phase, others are executed during the operation and completion (closure) periods.

TEN has ownership of RCAs and their execution is a legal responsibility of the holder, even if in practical and contractual terms execution may be transferred to different contractors of the Project.

Initiation and planning

TEN designed and maintains an Integrated Environmental, Health and Safety Management System, whose processes, plans and procedures allow and guarantee the control and fulfilment of the environmental requirements and responsibilities.

The environmental management of the Project involves three main companies: TEN as the holder and two contractors in charge of each of the two EPCs. The Technical Inspection (ITO) from the Owner Engineering (OE) support control and monitor of RCAs compliance and an external consultancy firm perform the technical inspection related to archeological issues.


TEN´s environmental management developed applying tools from its Management System. These include planning, execution, monitoring and control of fulfillment standards established in the Environmental Policy and in compliance with the commitments undertaken with the RCAs.

The commitments established in the RCA of the Project are addressed through management tools designed for the control and monitoring of the application of the RCAs in two areas of action:

  1. a) Monitoring of the compliance at the design stage: Environmental Manager meets with Engineering Manager on a regular basis to verify and validate the proposals of detailed design provided by the contractor. In the event of a discrepancy between what is required by the RCA and the final design, alternative solutions are discussed. These can be from engineering adjustments up to a request for the modification of the RCA. In the later scenario, tools from the Environmental Impact Assessment System (SEIA) are used, such as Letters of Pertinence to Submit the Changes to the SEIA, Environmental Impact Declaration (DIA) and/or Environmental Impact Studies (EIA).
  2. b) Monitoring of the compliance during the construction period: construction activities of contractors follow an Environmental Management Plan validated by TEN. Such plans include programs, procedures and/or guidelines, which allow them to plan, execute and control the correct implementation of the commitments established in the RCAs.  For example, each contractor plan has a procedure for induction and procedures for environmental release of working areas (flora, fauna and archaeology), allowing the identification and prevention of unforeseen impacts.

Monitoring and control

Compliance with the environmental commitments of RCAs during construction is periodically evaluated by ITO and directly by TEN. For this purpose, expanded checklists have been developed, containing all project commitments and reviewed every two months in work sessions led by TEN.

Environmental management during the construction period uses mitigation, reparation and compensation measures established in the project's RCA, integrating them through compliance programs that are part of the Management Systems used by contractors. The monitoring of the correct application of the measures and the control of the environmental variables is carried out on a permanent basis by the contractors themselves and by the Environmental Management Unit of the TEN.