Llandudno Magistrates’ Court heard that, on 15 January 2020, a blast at Cwt-y-Bugail Quarry in Llan Ffestiniog, Gwynedd, North Wales saw flyrock from the operation land 270m away, puncture the roof of an occupied work shed and put a hole in the outside pane of the occupied manager’s office skylight window.

An HSE investigation found that there were poor stemming practices, the written specification was prepared after the firing of the blast, and an inadequate danger zone was in place.

As a result there was a projection of flyrock outside of the danger zone that caused a quarry operative to run for cover and put other employees at risk when the roof of the shed they were working in was punctured.

Breedon Trading Ltd of Derby pleaded guilty to safety breaches and was fined £300,000 and ordered to pay £2,534.80 in costs.

After the hearing, HSE’s Adrian Jurg, HM Specialist Inspector of Quarries, said: “Blasting operations at quarries are inherently high risk, and these risks must be rigorously controlled by good explosives engineering practice and in accordance with legal requirements.

“It is unacceptable that employees, and potentially members of the public, be put at serious risk of being hit by rocks that could easily lead to death or serious injury.”