Olwyn Goch and the Milwr Tunnel

I am fortunate to have visited and explored this astonishing former Limestone and Lead mine, not once but twice. Access into Olwyn Goch and Milwr Tunnel was a challenge to say the least, certainly not for the faint-hearted.

The descent into Olwyn Goch, was via a series of 24 fixed ladders, installed onto the vertical wall of the mine shaft In the 1950’s, as an emergency escape route. Descending the 490ft (approx. 150m) Olwyn Goch shaft into the darkness below, ended by stepping off the bottom ladder, into very cold flowing water…

This huge mine is a fascinating place, given the scale of the many Cathedral like chambers and the amount and distance of tunnels and passages. Olwyn Goch is formed of a labyrinth of over 50 veins, extending over 60 miles of interconnected tunnels, chambers, lodes and natural caves. In mining, a vein is a narrow body of minerals or ore within rock. Whilst a lode, is a larger deposit of mineral or ore, often containing multiple narrow veins or layers.

This vast labyrinth, must be continually drained of water to prevent flooding. So in 1897, construction began on the Milwr Tunnel, a 10 mile long drainage adit, from Cadole near Loggerheads to Bagillt on the Dee Estuary. Built just above sea level with a gradient of 1:1000. The Milwr Tunnel, drains around 23 million gallons of water per day, from the Olwyn Goch system out to sea at ‘Bagillt’ on the North Wales Coast.

A map of Olwyn Goch and the Milwr Tunnel, showing the Veins, Lodes and Shafts forming the Olwyn Goch system. Along with the Milwr Tunnel’s route to the Dee Estuary. Map curtesy of Cris Ebbs and the Cambrian Mines Trust.

Olwyn Goch mine closed in 1986, the wires on the cage within the Mine Shaft were cut, the pithead demolished and the shaft sealed in 1987. The Olwyn Goch & Milwr Tunnel system became a time capsule when work in the mine finished. Many of the miner’s tools and their equipment, as well as the locomotives and hopper waggons as can be seen in the photographs, were abandoned where the miners had finished working that final day. Although some of the abandoned tools and equipment would be removed soon after closure of the mine, many artifacts still remain in the mine today.

There is a fascinating article about Milwr and Olwyn Goch, taken from Cris Ebbs’ book ‘The Milwr Tunnel – Bagillt to Loggerheads 1897 – 1987’ on the excellent Subterranea Britannica web site.