Chilean mine invites access project proposals Nov 2009
Shani Wallis, TunnelTalk
Location of the El Teniente Mine high in the Chilean Andes
- Seven international groups are preparing design-build proposals for construction of twin 9km long access tunnels to a new production level at Codelco's massive El Teniente Copper Mine in Chile.
- The parallel tunnels of about 10m wide and connected with cross passages at regular intervals, are required to provide roadways for the bus services run by the mine to transport hundreds of workers into and out of the mine. Access to the new underground mining area will also house a large capacity, 84in wide, production haulage conveyor system.
- El Teniente Mine is located approximately 85km southeast of Chile's capital city, Santiago, and access to the new production level is planned to start at an open excavation portal site within the narrow Rio Coya Valley near the existing mine refinery at an elevation of about 1,500m. The New Mine Level project is being planned to extend the life of the mine by 60 years with panel cave mining of a new 300m block progressing below existing mine levels and between elevation 1880m to 2100m. The New Mine Level Project is designed to maintain the mine's production at its tremendous 137,000 tonne/day as the panel caving continues lower to the required haulage level.
Alignment and geological section
- Procurement is being developed as a design-build project with a cost reimbursable incentivised contract. Reference design and contract documentation for the design-build project has been prepared by design engineer Hatch Chile, in conjunction with tunneling staff from Hatch Mott MacDonald in Canada/USA and Mott MacDonald in the UK.
- Geological and geotechnical conditions comprise mixed bedrock varying from competent, very strong volcanic deposits to highly altered, and weak rock with fault zones. Site investigation studies have included specialized rock testing for possible application of TBMs. A ground reference conditions report (GRR) has been compiled for the contract and this will be negotiated with the preferred proponent. Approximately 8,400m of geotechnical drilling has been completed for twin 9km long tunnels of the project. This has been supported with extensive laboratory testing.
- Pre-qualification of design-build proponents was completed in early 2009 and a mandatory site visit was made in September.
- The deadline for return of design-build proposals is early February 2010 and award of contract is expected by mid-2010. Advanced works for the project includes the construction of a large portal platform including bridge access over the Rio Coya that will be handed over to the tunnel contractor.
- The El Teniente Mine is one of the largest underground copper mines in the world and has been operating since 1905. It started operation as the Braden Mining Company before being taken over by the Kennecott Corporation and following that transferred to government ownership in 1971. The project has attracted significant interest from the international tunnelling industry with many of the world' s largest TBM and drill+blast tunnelling contractors showing interest in the design-build project.
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