Deep Navigation Colliery

Located next to the co-developed village of Treharris in the borough of Merthyr Tydfil, on development it was the deepest coalmine in South Wales Coalfield by some 200 yards (180 m).

In the early 1800s, a mineral lease was granted over 3,000 acres (1,200 ha) of land, owned by three farms: Twyn-y Garreg; Pantanas; Cefn Forest.

Nothing existed in the area at the time, except for the three farms and their outbuildings, plus the quiet River Taff Bargoed and a small forest on the slopes above the valley.

[3] With a proposed name of Harris Navigation Steam Coal Company, development commenced with the construction a row of temporary small houses, built for the families and men who were to be employed to sink the pit.

All materials for the huts' construction came from locally obtained resources within the bounds of the mineral lease, including the development of a firestone quarry to the north of the colliery site.

This included the installation of two John Fowler & Co. winding machines,[3] and the forest fully cleared, with wood stored for pit props.

Finally, the River Taff Bargoed was enclosed in a 0.3 miles (0.48 km) tunnel constructed of bricks made from the collieries quarry, enabling water ingress to the mine to be significantly reduced, and slag heaps to be placed on the resultant new land.

The only reason that funding had been forthcoming from the shareholders, commercial backers and banks was due to the potential high quality of the coal that could be extracted, and so it proved.

Supplied by the Perran Foundry of Truro, water was lifted in stages to different levels, until it reached the surface and was dispersed into pit pond located north of the colliery.

[3] Later, mine engineer Castell created the famous Deep Navigation “Castle.” A man-made cavern hewn by hand from solid rock, it was built to store water for removal.

Inside was installed an electric sump pump, which connected to a surface pipe that spilled into the same pit pond as the beam engine.

At the time this was signified by being selected by the Royal Navy, and the various transatlantic ocean liners, including the Cunard Line; hence the choice of the renaming.

[3] After supplying the Royal Navy during World War I, by 1920 the colliery was using the “Barry of Nottingham” system of coal cutting, a forerunner of longwall mining.

Investments included the demolition in the mid-1950s of the original 1870 Twyn-y-Garreg huts, but the site remained dormant almost until the colliery closed, when the new Navigation Street was built.

[3] Being located close, the colliery stopped working on announcement of the Aberfan disaster on Friday 21 October 1966, sending all available manpower to the recovery effort.

[3] In 1990, Deep Navigation was not added to British Coal's list of mines for closure, with a reported profit of £1 million to August 1990.

[5] However, a geological report issued in the autumn concluded that, due to structural problems in the surrounding substrata, coal reserves would only last until 1994.

[3] After a period of consultation with the greatly weakened National Union of Mineworkers, in January 1991, British Coal announced the closure of Deep Navigation from Good Friday, 29 March 1991.

[3] On the last working day, the Salvation Army band under the direction of Bandmaster Thomas Fredrick Willetts marched with the last shift to the town hall, accompanied by the MP for Merthyr Tydfil and Rhymney, Ted Rowlands, and the MP for Pontypridd, Dr Kim Howells, formally NUM South Wales research officer.

Just after the winding engine commenced, the 3.5 inches (89 mm) wide braided steel flat rope broke, sending four to their deaths at the bottom of the shaft 700 yards (640 m) below.

As a result, the brick tunnel in which the Taff Bargoed river had been redirected in 1873 was removed, and a landscaped parkland created either side of two new lakes.

Opened in time for the Millennium, the park was named Parc Taff Bargoed, now home to many local rugby and football teams.