SOFT GROUND TUNNELLING | TECHNICAL
Additionally, the LDMP is to also design to deliver
substantial environmental quality improvements as well as appreciably enhance the city’s resilience to large flood flows resulting from high-intensity rainfall events. In total, the strategic drainage improvements over
2016-2030 represent the largest investment ever made by the municipal authority, at Euro 250 million. Almost half of the total budget is funded by loans from the European Investment Bank (EIB). More than half of the total spend - about 60%, or Euro
150 million - is required for the underground works. The project (in Portugues is known as Plano Geral de
Drenagem Lisboa (PGDL)) is being undertaken by the city council - Camara Municipal de Lisboa
LDMP CONCEPT - FURTHER DETAILS The origins of the LDMP strategy are from discussions and early proposals starting in 2004, which led two years later to planning works with the consultancy consortium Chiron/ Engidro/ Hidra. A first plan was produced in 2008, considering flood management for one in 10-year rainfall events, but funding problems stalled implantation of the strategy. Resurrected in 2014, the LDMP was then updated -
including to handle one in 100-year rainfall events. The new plan had a focus on the main tunnels plus the basins. A 15-year delivery period to 2030 is planned. The drainage tunnel concept is not only about flood
impact mitigation; the LDMP also includes an internal water recycling distribution system to promote circular economy through water reuse in the city. Recycled water from the Alcântara Wastewater
Treatment Plant is to be distributed throughout the city centre for various activities, such as irrigation of green spaces, street cleaning, and potentially firefighting,
thereby saving potable water and reducing costs for citizens. It is important to notice that the LDMP is an innovative
and comprehensive strategy designed to tackle the challenges posed by climate change, particularly the intensification of pluviometric events - with such rainfall events potentially leading to more frequent and severe floods in Lisbon. The use of innovated technologies and processes,
in particular Building Information Modelling (BIM), integrates all relevant project information, facilitating communication among various entities, helping the evolution on the design and also enhancing the construction process’s quality and efficiency. BIM also allows for anticipating and resolving construction issues and preparing for infrastructure maintenance and exploitation, thus adding long-term value to these assets. The Lisbon Municipality was the first public entity
that prepared the tender in order to promote use of BIM, as mandatory for the design phase, as well as the construction and future lifecycle of the infrastructure associated with the LDMP. This strategic plan, therefore, aligns with the themes
of climate change, circular economy, and innovation. Its guiding principle is to develop an integrated flood control solution for Lisbon and provide the city with structural drainage infrastructure prepared for the challenges of the 21st century, while promoting water reuse and efficient use of underground space.
CAPACITY - BASINS AND UNDERGROUND The main construction activities on LDMP are already ongoing, following initial works on retention basins (in Ameixoeira, Alto da Ajuda, and Parque Eduardo VII),
Left:
Constructed drainage tunnel lining (Left) and work on a large diameter, deep shaft along the alignment (Right)
November 2024
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