This project aims to construct two tunnels, the Monsanto-Santa Apolónia Tunnel (TMSA) and the Chelas-Beato Tunnel (TCB), with the goal of implementing two independent drainage systems in the city of Lisbon, capable of effectively addressing rainwater drainage needs.

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These infrastructures will be constructed using a tunnel boring machine (TBM).

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The Monsanto – Santa Marta – Santa Apolónia Tunnel (TMSA), with an internal diameter of 5.5 meters and a length of 4.60 km, extends from Campolide to Santa Apolónia, intercepting the rainwater flows from the urban watersheds of Alcântara, Av. Liberdade, and Av. Almirante Reis (a watershed of 2,900 ha).

The tunnel is designed for a 100-year return period and will have the capacity to discharge flows exceeding 160 m³/s.

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The Chelas – Beato Tunnel (TCB), with an internal diameter of 5.5 meters and a length of 1.48 km, aims to resolve flooding problems in the Xabregas area by diverting the flows from the drainage system of Estrada de Chelas (a watershed of 1,700 ha).

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Several works are associated with both tunnels, which are summarized in the following list:

Monsanto-Santa Apolónia Tunnel (4.60 km)

• Tunnel (TMSA)

• Diversion work for the Alcântara sewer to the entry structure (TM1)

• Diversion and intersection work at Avenida da Liberdade (TM2)

• Diversion and intersection work at Santa Marta (TM3)

• Diversion and intersection work at Avenida Almirante Reis (TM4)

• Discharge work at Santa Apolónia (TM5)

• Drainage system for domestic and rainwater in the lower basin of Santa Apolónia, around the TMSA discharge area (TM6)

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Chelas-Beato Tunnel (1.48 km)

• Tunnel (TCB)

• Diversion work for the Chelas sewer to the entry structure (not included in this contract)

• Discharge work in the Doca do Poço Bispo area

• Drainage system for domestic and rainwater intercepted by the TCB discharge work

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