Problematic: The Abaro collector, as it passes through Zumalakarregui at the height of the Campa de las Piedritas. The aforementioned elbows are considered very susceptible to collapse in the short to medium term. This would imply a catastrophe since they are not accessible to maintain or repair them, in addition to being 30 meters deep in rock, making any emergency work from the surface impossible. This situation is worsened since part of the network runs under the Metro tracks.

How it was resolved: Construction of a visitable gallery with interior span dimensions of 1.00 m. wide x 1.80 m. high, with its corresponding concrete quality gutter. Given the complexity of the work, as it is located up to 30 meters deep in rock, in a main area of Bilbao and with the metro line attached to the work, it is proposed to create a new gallery in the mine (red line in the attached image ) to intercept the collector (orange dashed line in the image) and divert it from conflict areas.