Following Storm Christoph in January 2021, the town of Skewen, near Neath in South Wales, was subjected to flooding from below ground, erupting out of manholes and forgotten shafts from the area’s past coal mining heritage, covering possessions in thick ochre slurry and resulting in the evacuation of 100 residents.
Neath Port Talbot Council and the Coal Authority (CA) who led the investigation concluded a high volume of rainfall had filtered into the hillsides above Skewen, which are pockmarked with mine shafts. Initial reports from the CA showed that water had found its way into the abandoned mine workings and into a specific shaft that emerged directly at the water table, as water found a natural point of weakness to escape, possibly from a blockage in the drainage system which may have caused the mine shaft to “blow out”, building up pressure behind the shaft entrance before it released a high quantity of water in a short space of time.
Following the CA's investigations and engineering design work, a new system is now under construction to collected excess water caused byprolonged rainfall, reducing the risk of future groundwater flood events. Including additional engineering needed to stabilise the ground around the blowout to provide the necessary foundations for the new pipe work and mine water capture structure. This is due to unique geology discovered on site.
The system will include new boreholes and a concrete capture structure to collect and route the mine water into a new culvert. It also features real-time telemetry monitoring. Work has been undertaken in partnership between NPT Council, the CA and Natural Resources Wales.