The environmental study of the metro at Son Espases warns that the route passes through areas at risk of flooding

PalmaThe future expansion of the Palma metro to Son Espases hospital, which has already been released for public information and represents one of the most ambitious mobility actions in the short term by the Government, crosses areas with a high risk of flooding. The project incorporates an environmental impact study that confirms this structural condition, as it affects all proposed alternatives and can determine both the final route and the environmental viability of the project.

The analyzed action corresponds to the extension of the existing line from the UIB to Son Espases, a short stretch, of a few kilometers, but with a notable environmental complexity. At this stage, it is not yet the construction project that is decided, but the corridor through which the metro must pass, and the hydrological factor becomes decisive. Sources from the Ministry of the Water Cycle have explained to ARA Balears that "preferential flows must be respected, as stipulated by regulations, and the necessary measures must be taken." "But this does not make the project impossible," they said.

Sources from the Directorate General of Mobility explain that "the informative study is a multicriteria analysis." "It incorporates technical, environmental, social, and economic parameters. The investment for each of the alternatives is calculated, which, among many other technical issues, analyze the effect of water (floodable area or route below or above the water table)," they comment.

According to the environmental study, the Government's alternatives to extend the line are within the basin of the torrent de na Bàrbara and the torrent Gros, and they must cross areas identified with a significant potential risk of flooding. The document points out that “all of them must resolve the crossing of na Bàrbara, with the presence of associated flood risk areas (T=500),” a situation that makes this point the main hydrological obstacle of the project. This implies that, regardless of the chosen route, the metro will inevitably have to pass through an area with a high risk of flooding, with no possibility of avoiding it. "The corresponding measures must be taken, which may increase the cost of the project, but by no means call it into question," emphasize sources from the Ministry.

The entire route is conditioned by being within an active hydrographic basin, and any action may have effects on the overall drainage of the area, where scattered populations live, except for some points along the route where the populated area intensifies.

The two journey options

Regarding the itineraries, the study proposes two main alternatives. The first option branches off the current line at Son Fusteret (see the image illustrating the article) and outlines a route with intermediate stops in areas of equipment and activity, with stations at Son Hugo, Son Rossinyol, and the surroundings of Son Espases – with a possible extension to Son Serra Perera. The second alternative follows a more linear path linked to the Camí dels Reis, with stops at the main intersections — such as the Sóller road — and also with stations at Son Espases and Son Serra Perera. Both options run mostly through urban land and aim to connect with the hospital as the main mobility hub, but with differences in the route and the distribution of stops.

The type of infrastructure envisaged amplifies the risk. Although it is a metro, the study acknowledges that the project may combine underground and surface sections. In any case, the underground sections are particularly sensitive. The document warns that “routes with aerial components tend to generate more physical presence and potential visual impact, while predominantly underground routes reduce this effect, but concentrate the transformation in specific points”, such as tunnels, stations, and accesses. If it is underground, the risk of flooding does not disappear, but rather it is concentrated, with possible direct impacts on the infrastructure, such as water entering tunnels, phreatic level filtrations, and problems with drainage systems, among others.

A more sensitive context

In this context, especially after recent episodes of severe floods in the Valencian Community due to the 'dana' (cold drop), the debate on the implementation of infrastructure in flood-prone areas has gained prominence. Environmental and social organizations, such as the GOB in Mallorca, insist on the need to apply the precautionary principle to any project affecting these areas.

The impact is not only on the metro, but also on the environment. The environmental assessment document warns that the infrastructure may interfere with "the natural behavior of water," as the implementation of the route “may significantly modify the free circulation of water, represent an obstacle to the flow of surface runoff, or increase the pre-existing risk”. This is one of the most sensitive aspects from an environmental and legal point of view, as regulations require ensuring that any action in a flood-prone area does not worsen the existing situation. Therefore, the project will have to pass strict controls and obtain specific hydraulic authorizations, with the need to technically justify that it does not increase the risk.

Detailed analyses are lacking

Despite the importance of this condition, the study acknowledges that its real impact cannot yet be precisely determined, as the project is in a preliminary phase. Key elements such as the construction system, the depth of the tunnels, and specific drainage solutions have not yet been defined, factors that are decisive in assessing the final risk. In this regard, the document raises the need for more detailed analyses in later phases, with specific studies on floods, the water table, and extreme rainfall events, in addition to evaluating vulnerability to climate change.

According to the project that the Government is submitting for public consultation, in a second phase, the aim is to extend the metro beyond Son Espases, to the Riskal roundabout, where the new private medical faculty of San Pablo CEU will be located.