Milwr Tunnel was constructed between 1897 and 1957 to drain water from lead mines between Holywell and Mold in North Wales. The 10-mile tunnel runs from Loggerheads to Bagillt, discharging approximately 23 million gallons of water per day into the Dee Estuary.
In 2013, remedial works were identified as necessary. These works required the Herward shaft—located about 2,500 metres inland from the portal and 175 metres deep—to be repaired and re-equipped. This upgrade was essential to allow safe personnel access and provide a secondary means of emergency egress.
Work completed:
All SES personnel completed specialist water rescue training before starting tunnel works. With water levels reaching up to one metre, small boats fitted with electric outboard motors were used to transport workers and equipment. To ensure safety, communication between the underground team and surface control was maintained via Leaky Feeder and EMCOMM systems.
The project was successfully completed on time and within budget
Water draining from lead mines