The 111-MW Chacayes hydroelectric project is set in the mountainous terrain of the Chilean Andes in an area characterized by rain and glacier-fed streamflow, significant sediment transportation and young geology.

The project is located at the bottom of the development from an elevation of 1105 m to just upstream of the existing Coya hydroelectric
project owned by Pacific Hydro Chile.

The Chacayes project consists of the following components:

• Cachapoal River intake at elevation 1105 m
• Cipreses River intake at elevation 1130 m
• Combined design flow from the two intakes of 72.5 m³/s
• Desander for the combined flow from the two intakes
• Intra-daily peaking storage pond
• Sections of canal, tunnel and inverted siphon and penstock to connect the intake, storage pond and powerhouse
• Two-unit surface powerhouse with an installed capacity of 111 MW

Scope of Services
Hatch prepared the basic design and definition designs for the project as well as the Owner’s technical requirements, including drawings and specifications for civil structures, and mechanical and electrical systems.

The work included:

• Phase 1 – Preparation of an inception report including the review of a previous optimization study. Development of basic engineering, sufficient to define the structures for permit applications to the relevant authorities
• Phase 2 – Refinement of basic engineering to a definition stage, preparation of drawings and specifications required so that the EPC construction contracts for the project works could be tendered

This also included assistance in evaluation and award.

Hatch is now acting as Owner’s Engineer, responsible for reviewing the EPC contractor’s detailed civil design and drawings and equipment supply.

Project Highlights
The Chacayes project is the first in a series of potential greenfield developments on the Cachapoal River with upstream projects being studied by Hatch including the Nido de Águila and Las Leñas hydroelectric projects.

The Cipreses diversion and intake is located in a national reserve and this required careful consideration of the visual impacts of the diversion structure on the area. Access to this site for construction was provided through the diversion tunnel so as to minimize the development of infrastructure (roads, etc).

When coupled with the potential redevelopment of the existing Coya project located downstream of the Chacayes project, there are significant operational coordination benefits to be gained.