SPLIT PERSONALITY - Penrhyn Slate Quarry

SPLIT PERSONALITY

From Big Issue in the North magazine, December 3-8th 2013. 

From a great hole in a Welsh mountain, slate has been quarried for two thousand years and is prized because it splits cleanly. Only a handful of quarries remain today but, as Mark Metcalf finds, those in the trade are determined to maintain a proud, ancient tradition.

Ever since Roman times there has been slate quarrying in north west Wales but the techniques used to extract it then are different from the ones used today.

Then the slate was used for a weathertight roof on a fort built just outside Caernarfon. By the 19th century the industry dominated the region. Working conditions though remain difficult and there is a constant geological battle to ensure there is a safe working environment in which to remove a metamorphic rock valued for its splitting characteristic. The word slate is derived from the French verb esclater, meaning “to split”, and the rock’s final splitting is still completed manually by workers.

Penrhyn Slate Quarry outside the small village of Bethesda in North Wales was first developed commercially in the 1770s. It went on to become the world’s largest slate quarry at the end of the 19th century century. Larger quarries now exist in Spain, China and the US, but Penrhyn remains Britain’s biggest.

The company Welsh Slate, which also includes smaller quarries locally, manufactures on site each week around 125,000 roofing slates, as well as decorative aggregates for paths and gardens. This provides jobs for around 100 people during processing and 20-plus in the actual quarry itself.

The quarry is a great hole in the mountain and its black sides contrast greatly with the grandeur of the surrounding mountains. The main working pit is 1.6km long and 150 metres deep.
There are 15 metre benches or terraces on open galleries on each mountainside.

The slate itself starts 60 metres below ground. Removing the overburden – or waste – is an ongoing process and in the last year contractors have stripped two million tonnes in order to widen the quarry and free up more slate. The colour of the slate is dependent on the chemical composition of the mudstone, which was deposited at Penrhyn around 500 million years ago. Most slates from Penrhyn are heather blue in appearance.

Extracting the slate involves taking advantage of the natural weaknesses in the rock through planes and joints to take out large blocks. According to Dafydd Williams, the quarry manager at Penrhyn for seven years, the perfect size block is 10 metres by 10 metres.

Since Irish businessman Kevin Lagan purchased the quarry six years ago there has been significant investment. This has included a new machine in which wire impregnated with diamonds is used in cheese wire fashion after probes have been employed to link the vertical and horizontal cuts.

Although explosives are then employed to bring down the loosened rock the process has lessened the danger of falls as the quantity of shot used is considerably less than before. Nevertheless in the last few years there have been two major rock falls in the quarry, including one of six million tonnes. Fortunately, both falls were at night and no one was injured.

Williams says: “The skill is to understand the geology of the quarry. It could be very dangerous as the cleavage of the slate is vertical but you’ve got sub-joints that are parallel.

“If you don’t understand those joints, and recognise that by moving one block, it will impact on those near to it then you could have problems.”

Williams’ target is 3,000 tonnes of productive slate a week from the quarry. Huge loaders and massive Volvo trucks are used to carry giant blocks of stone to the processing plant. En route the drivers pass two zip wires specially constructed in a disused area of the quarry. Zip World opened earlier this year and visitors pay £50 to reach speeds of up to 100mph. The company rents the space from Welsh Slate and the entry fee also includes a brief quarry tour.

Once the slate blocks reach the processing plant a hydraulic splitter is employed to split the slate to a size that can be sawn. When production manager Andy Smith started work at Penrhyn 30 years ago this breaking down of the stone was done manually with a sledgehammer and chisel. It was back-breaking work.

Fork-lift trucks transport the smaller blocks to the sawmill, where four saws reduce further the size of the stone to various sizes, of which the most popular among customers is 20 by 10 inches. This is known as the Countess, with different sizes of slate all named after female aristocratic titles.

The remaining stone is deposited with the splitters, whose job it is to determine the thickness of the finished slate. This depends on the quality of the slate as well as the skill and experience of the worker.

Wayne Eccles started work on a training scheme in the early 1990s and was given 32 weeks training in splitting. He says: “The skill is in the eye as you always split slate in half. Some people use their thumb to decide on what thickness the slate will be.”

The splitters are the only employees whose contracts include bonus payments – which can vary from £50 to £150 a week – and they make more if they can create roofing slates that are thin rather than thick. As we are talking millimetres in difference then that is no easy task.

Eccles followed his father into the quarry industry and so did Neil Roberts, whose link to quarrying goes back six generations to 1823. He is aware of the strike that ran for three years starting in 1900 and like the majority of workers is a member of the trade union Unite.

Industrial relations at the quarry today are, says Roberts, “pretty good as we need to keep the quarry open as without it there would be few local jobs and Bethesda would struggle to survive”. A large local employer has recently closed and across Wales the jobless rate is 8.2 per cent, higher than England.

The completed slates are checked and packed before being supplied to restoration, repair or new-build projects in the public, commercial and residential building sectors. Architects and building contractors often specify they want slate as it has a reputation for style and longevity. Welsh Slate offers 100-year guarantees.

The Fountain in Exchange Square in Manchester was constructed with slate boulders from Bethesda. The Welsh Assembly building in Cardiff used slate walling, paving and flooring from the Penrhyn quarry. All of which gives a special pride to the workers. “It is nice to see something that I have done that is going to last a long time,” says quarry operative Carwyn Jones.