Milwr Tunnel

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Milwr Tunnel was constructed between 1897 and 1957 to drain water from the lead mines between Holywell and Mold in North Wales. The tunnel is 10 miles long and runs from Loggerheads to Bagillt where it discharges 23 million gallons per day into the Dee Estuary. 

During 2013 it was identified that remedial works were necessary in the tunnel which would necessitate the Herward shaft (some 2500m inland of the portal and 175 metres deep) being repaired and re-equipped to facilitate people access and also to provide a second means of egress in case of emergency. SES' Special Projects installed and commissioned the shaft access system to NIMM standards and then repaired the identified areas throughout the tunnel length.

The entire SES workforce underwent specialist water rescue training for the tunnel works. The tunnel water was up to one metre deep and small boats equipped with electric outboard motors were utilised for the transport of men and equipment. Communication between the underground workforce and surface control was maintained by a combination of Leaky Feeder and EMCOMM systems as a key safety measure.

The project was successfully completed on time and within budget.