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A 943-meter underground tunnel has begun to be excavated in Xanxerê, in western Santa Catarina, to combat flooding that has plagued the city for over 40 years. The macro-drainage project, budgeted at R$ 20 million, uses controlled detonations and will reuse the extracted rock in the paving of urban and rural roads.
Floods, losses, and fear of rain have been part of the routine for many residents of Xanxerê, in western Santa Catarina, for more than four decades. Now, a project considered historic is advancing with the promise of changing this reality: an underground macro-drainage tunnel that will create a new path for rainwater and reduce the flooding that affects entire neighborhoods of the city. The structure began construction in April 2026, the result of a partnership between the Government of Santa Catarina and the Xanxerê City Hall.
With an investment of R$ 20 million, the underground tunnel will be 943 meters long, equivalent to almost a kilometer, and will be excavated between 30 and 60 meters below the surface. The goal is to increase the flow of rainwater and minimize the impacts of floods that, for decades, have compromised urban infrastructure and limited the growth of the municipality. The project connects the central region of Xanxerê to an old rock extraction area near BR-282.
How the underground tunnel will work
The logic of the project is simple in conception and complex in execution: to create an alternative underground route for rainwater, making the drainage faster and more efficient than the current surface system can offer. By diverting the flow of rainwater to the underground, the tunnel reduces the pressure on urban areas that historically flood during storms.
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A vertical shaft will be implemented along the route of the underground tunnel, technically known as a “shaft,” responsible for capturing drainage water and directing it into the structure. After traveling the 943 meters of the tunnel, the water will be channeled to the Xanxerê River, about 125 meters from the project’s endpoint. The project also includes rock excavations, reinforcement of the internal walls with concrete, and the installation of complementary devices to ensure the safety and efficiency of the entire drainage system.
Controlled detonations and 14 months of excavation
The construction of the underground tunnel officially began on April 22, according to the Xanxerê City Hall. The initial stages involved cleaning the area, removing the organic soil cover, and initial open-air rock excavations, preparing the ground for the most delicate phase of the work.
Subsequently, the opening of the tunnel in the rocky massif began, with underground excavations and controlled detonations, a technique that requires precision and constant monitoring to fragment the rock without compromising the surrounding stability. The excavation phase is expected to be completed in approximately 14 months. The municipal administration reported that engineering teams are monitoring the work daily, overseeing both operational safety and adherence to the established schedule.
The removed rock becomes material for roads
One of the most interesting aspects of the project is the utilization of the material extracted during the excavation. Instead of discarding the enormous amount of rock removed from the subsoil, the municipality plans to reuse it entirely, a solution that reduces costs and waste, transforming a byproduct of the work into a useful resource for other infrastructure fronts.
After undergoing crushing, the stones extracted from the underground tunnel will be used for road recovery and as a base for asphalt paving on urban and rural roads in Xanxerê. It is a cycle that makes economic and logistical sense: the same material that needs to be removed to open the tunnel ends up paving the way for those living in the city and the countryside, expanding the positive impact of the work beyond flood control.
A project awaited for 40 years
For the Xanxerê community, the underground tunnel represents much more than an engineering intervention; it is the possible solution to a problem that has spanned generations. Governor Jorginho Mello stated that the project is part of the actions to prevent extreme weather events carried out in different regions of Santa Catarina, describing it as another macrodrenage project in Western Santa Catarina aimed at solving a decades-old problem.
The mayor of Xanxerê, Oscar Martarello, highlighted the potential of the intervention to end a history of more than 40 years of flooding and bring peace of mind to the population. Meanwhile, the Secretary of Infrastructure and Mobility, Ricardo Grando, classified the project as the most important agreement among the more than 2,000 signed with municipalities in Santa Catarina, precisely because it has a direct and objective impact on people’s lives. For a city that has learned to fear the rain, the expectation is that the tunnel will transform this relationship of fear into safety.
What changes in the life of those who live in Xanxerê
The impact of a project like this goes far beyond technical numbers. Families who lost furniture, appliances, and even documents in floods over four decades live with a loss that is financial but also emotional. Each strong storm meant nights of vigilance, flooded homes, and the exhausting work of starting over after the water receded.
If the underground tunnel delivers what it promises, the impact will be felt directly in mobility, safety, and the quality of life of the population. Neighborhoods that were previously isolated during rains will be able to maintain normal operations, local businesses will suffer fewer interruptions, and urban development that was stalled due to the risk of flooding can finally progress. It is the type of infrastructure project that does not appear in the landscape, hidden dozens of meters below the ground, but whose effect people feel every time the sky darkens.
Do you live in Xanxerê or know someone who has suffered from floods in the city? Do you believe the underground tunnel will finally solve the 40-year problem? And in your city, which infrastructure projects do you consider most urgent? Leave your opinion in the comments, and tag that friend from Xanxerê who is waiting for this project.
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