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Historic Penrhyn Quarry to extend slate working

08 Nov 2022 4 minute read
Splitting Sheds and Crushing Plant at Penrhyn Quarry. Photo by Eric Jones is licensed under CC BY-SA 2.0.

Dale Spridgeon, local democracy reporter

Plans to extend operations to help meet global demand for Welsh slate from an historic Gwynedd quarry have been unanimously approved.

The move will see 250,000 tonnes of purple roofing slate and 1.9 million tonnes of red/blue decorative slate extracted from Penrhyn Quarry in Bethesda.

The quarry will now see operations continue until 2035, with further work to restore the site continuing until 2037. According to the applicant, the extension also means securing 115 skilled jobs.

Penrhyn was one of the largest and most productive slate quarries in the world. Large-scale slate quarrying has been carried out there since the 1770s.


It was famously the location of two prolonged strikes by workers demanding better pay and safer conditions.

The first strike lasted for eleven months in 1896, and the second began in November 1900 and lasted three years.

At a meeting of Cyngor Gwynedd’s planning committee on Monday planning officers recommended approving a submission for the ‘lateral extension’ to the working area of the quarry.

The extension to the works would include 1.6 hectares of land, with the application site including a total of 2.26hectares.

The need for the extension was the result of a vertical dolerite dyke that crossed the south western face of the existing extraction area.

“Slates within approximately 25m of this dyke are intensely fractured to the point that no workable material can be recovered resulting in a loss of around 1.11 million tonnes of premium slate,” the planning report explained.

It was intended to work the extraction extension area “in the same manner” as the current working agreements including waste tipping, stockpiling, and production of roofing slates.

It would also see the monitoring of dust and complaints, working hours, restriction on noise and mitigation of the impact of blasting methods.


Regarding traffic issues, there would be “no change” to HGV movements in accordance with previous arrangements.

An existing drainage leat would intercept surface water and water management measures put in place.

The development, would also see the demolition of a medieval multi-cellular sheep fold. Recording of the feature would be carried out by archaeologists.

A report considered its loss to have only “a small indirect impact on the historic landscape”. There was also considered no impact on the area’s World Heritage site status.

A separate planning application for a variation of the existing planning conditions was also submitted to extend the working lifespan of the quarry and amend drawings to match the latest proposed extension.

The second application, under Section 73, to vary condition 1 and 3 on planning permission, would extend the time for excavation and working of material up to 2035, extend the time for the restoration of the site up to 2037 and amend plans to include an extension to the excavation area.

Mr Shaun Denny of Breedon Trading Limited, trading as Welsh Slate, speaking in person, said: “There are two separate planning applications here, and they will facilitate slate production to continue at the quarry until 2035.


“It is a geological anomaly in the site that has hampered production. These plans mean we will be able to extract Welsh slate, premium, Penrhyn purple roofing slate, up to 250,000 tonnes, for which there is a world wide waiting list.

“It would also see the production of almost two million tonnes of red and blue slate marketed as a decorative product. If approved these plans will give us a firm basis to make decisions on capital expenditure, increase the number of slates produced and sold, and allow us to create a broader product range.

“It also means , 115 skilled jobs. With the quarry’s history and and recognised place in the community, our hopes are to secure a bright future for the area and site.”

In the vote, both planning applications, were unanimously approved.

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1 year ago

Thank God for some solid good news!

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