A study proposes ways to control unforeseen leaks in underground excavations.

The study analyses three real cases in Valencia and proposes different strategies to prevent leaks.

A study involving the IIAMA Institute at the Universitat Politècnica de València (UPV) proposes a series of solutions to address a critical engineering problem: unforeseen water leaks during the construction of deep excavations.

The work, carried out by Alejandro Ferrer (Ferrer Dewatering, S.L.), Eduardo Cassiraga (IIAMA-UPV Hydrogeology Group), and Jesús Carrera (IDAEA-CSIC), focuses on controlling groundwater in urban environments. This technical challenge is accentuated when attempting to reduce the environmental and economic impact of pumping.

To this end, it analyses three real cases in the city of Valencia, where excavations below the water table suffered uncontrolled inflows caused by construction defects, poorly sealed boreholes or confined aquifers that were not detected during the design phase. 'These situations can compromise the stability of the work and generate high economic and environmental costs, so having rapid and effective action protocols in place is essential, explains Eduardo Cassiraga, a researcher at IIAMA-UPV and co-author of the study.

Causes of groundwater leaks

Among the most frequent causes, the study identifies old unsealed wells or boreholes, defects in slurry walls and the compartmentalisation of the ground by internal foundations, which limit the flow of water to extraction wells.

For each of the cases analysed, the authors propose different strategies to be applied directly on site: from in situ sealing using piping and cement grouting to the installation of high-permeability drainage layers or the injection of expansive resins to seal leaks.

'These actions can restore hydraulic and mechanical stability without increasing pumping, thus reducing energy consumption and environmental impact,' says Eduardo Cassiraga.

Prevention is the most effective tool for avoiding incidents.

The study emphasises that prevention is the most effective tool against these incidents. Therefore, the researchers recommend implementing continuous monitoring and control plans that allow faults to be anticipated before they affect the development of the work. Among the key measures are monitoring pumped flows, observing piezometric levels using sensor networks, and coordinating geotechnical and drainage designs.

The study also emphasises the need to immediately seal geotechnical boreholes and piezometers after use, particularly in the presence of confined or semi-confined aquifers. It proposes specific solutions for cases with internal foundations that compartmentalise the subsoil, such as the use of sectorised pumping or drainage gravel layers that allow dry working without compromising stability.

'The initial cost of monitoring is much lower than that of unexpected seepage, which can cause delays in construction or affect adjacent buildings. Understanding the hydrogeological behaviour of the ground allows for the design of safer, more efficient and sustainable drainage systems,' conclude the authors.

Reference

Alejandro J. Ferrer Granell, Eduardo Cassiraga, Jesús Carrera. Remediation of uncontrolled inflows caused by technical failures in deep excavations. Results in Engineering 27 (2025) 106581. Science Direct.

https://www.sciencedirect.com/science/article/pii/S2590123025026507