Site Records


SiteName: Milwr Tunnel

Olwyn Goch Shaft
Rhydymwyn, Flintshire
OS Grid Ref: SJ201677

Sub Brit site visit August & November 1997

[Source: Cris Ebbs]

This text is from Cris Ebbs book (reproduced with permission) 'The Milwr Tunnel - Bagillt to Loggerheads 1897 - 1987' ISBN 0 9522242 0 8

The first people known to have mined for lead in Clwyd were the Romans. They worked those veins that outcropped at the surface on Halkyn Mountain, Meliden, Abergele and Minera and formed the ore into ingots for shipping from the coast at Flint. Following the departure of the Romans it seems that virtually no mining was taking place in the area until the 13th century, when local farmers attempted to supplement their incomes by small-scale operations, limited to shallow pit or trench-type excavations. Ore at this time could still be found at or very near the surface and mining continued intermittently along these lines until surface deposits had been exhausted around the 17th century. Flooding became a problem when deeper working was limited by the pumping technology available.


Course of Milwr Tunnel & Rhosesmor Branch

Things began to improve by the late 1600's when increased ore prices and improved technology resulted in deeper shafts and the driving of adits to drain the workings. By the 1890's many mines had been worked out, at least as deep as water levels, kept down by pumping, would allow. But in 1897 an amalgamation of mine companies began an ambitious scheme to drive a deep drainage tunnel from sea-level at Bagillt. This tunnel, known as the Milwr (Pronounced Milloor) or Sea-Level Tunnel was eventually driven a distance of 10 miles to Cadole near Mold by the year 1957.

It successfully drained over 50 veins and created a labyrinth of over 60 miles of interconnected passageways. At a time when low ore prices were decimating the industry, the Milwr Tunnel was cutting previously unknown veins and making profits from the systematic exploitation of known veins by the removal of ore down to, and even below, sea-level. During the 1930's up to 650 men were employed by the mine and tunneling records were being broken.

The Milwr Tunnel was begun in July 1897 from a point 9 ft. below high water mark at Boot End near Bagillt (SJ 213 760) by the Holywell-Halkyn Mining and Tunnel Company. Two self acting flood doors were installed to prevent inundation by the sea at high tide and the tunnel headed south-west towards Herward Shaft. The tunnel gradient is 1:1000 throughout. It is initially circular in section, 8 ft in diameter with a channel for water in the floor lft 6 ins deep by 6ft wide. Rails were laid on timbers above the water channel. The tunnel walls are brick lined for 1.5 miles where the tunnel passes through shale and coal measures, but thereafter is in chert or limestone and is generally self-supporting. The tunnel south from this area changes to a square section of 8ft x 8ft. From Herward Shaft it passed through Milwr Mine for a short distance to Caeau Shaft on Caeau Mine, where driving stopped 2 miles from the portal in 1908. The tunnel, at this time, drained an average of 1.7 million gallons per day or 1200 gallons per minute. The fastest rate of tunneling was 54ft a week.

Photo:The Milwr Tunnel close to Olwyn Goch Shaft
Photo by Nick Catford

In 1913 an Act of Parliament allowed the company to extend the tunnel which reached the limit of its mineral boundary in 1919 at the hamlet of Windmill on Halkyn Mountain. Rates of advance of 40 to 45 ft a week were achieved during the early years of the first World War. A two shift system was operated; one drilling, the other for shooting (blasting) and "mucking out". Each charge or blast gained an advance of 4 ft.

Upon reaching the companies boundary in 1919 Caeau Shaft was sealed off and all work on the tunnel was again halted. At the intersection of the Pant Lode, a flooded cavern, known locally as a loch or vugh, was cut at 6 a.m. on 5th January 1917 which caused St Winefrides Well at Holywell, 2.5 miles to the north, to run dry 11 hours later. The burst of water swept loaded trucks along the tunnel until they jammed and sand blocked the tunnel, being 2 ft deep at the entrance, seriously hampering progress for many weeks. Water levels in a number of neighbouring mines were also affected.

Olwyn Goch headframe and winding shed

Following a takeover in 1928 by the Halkyn District United Mines Ltd., Caeau Shaft was re-opened and the 5000 ft to the tunnel face at Windmill was reconditioned to cope with the large volume of water now flooding the rails.

The tunnel floor was sectioned off and one side filled with debris from the face upon which the rails were laid 3 ft above the original floor. The tunnel now rapidly pushed south beneath the Catch area reaching Pen-y-Bryn Shaft in July 1929. Driving south the tunnel was now driven larger in section being 10 ft wide and 8 ft high. A water channel, known by an American mining term as "the grip", was cut to one side of the tunnel 4 ft wide and 2 ft deep. A major branch tunnel was driven east from a point three-quarters of a mile south of Pen-y-Bryn. This was driven for one mile to Rhosesmor where Barclay's Load and Powell's Load yielded major deposits and were worked successfully for many years.

Photo:A man rider in the Rhosesmor Branch
Photo by Nick Catford

As the tunnel progressed southwards to Hendre, an old shaft known as Olwyn Goch was enlarged to 12 by 12 ft 6 ins and deepened to 490 ft the bottom being 27 ft below tunnel level. It was chiefly used for raising men and materials only until the 1940's when limestone quarried underground was raised here, Pen-y-Bryn Shaft being used for winding ore and materials. At the surface close to Olwyn Goch Shaft were the offices, changing rooms, bath houses and lamp rooms sufficient for 500 men. For ease of access, a passage was driven into the shaft from a point immediately behind these buildings. Fixed ladders, supported by platforms in the side of the shaft, also provided an alternative route to surface for the men in an emergency

Further information and pictures about this site continues here

[Source: Cris Ebbs]

Home Page
Last updated: Tuesday, 04-Jan-2011 14:55:23 GMT
© 1998-2003 Subterranea Britannica