Gleision Colliery

Overview

Gleision Colliery was a small, privately owned drift mine at Cilybebyll in the Tawe valley, one of the last handful of working coal mines in the South Wales coalfield, until a blasting operation on 15 September 2011 breached adjoining flooded workings and killed four of the seven miners underground.

History

Gleision Colliery was a small drift mine working the shallow, 2 feet 6 inch Ynisarwed seam at Cilybebyll in the Tawe valley, in the same district as the much larger, long-closed Tarenni Colliery. Development began in 1962, with the mine's current two-drift layout in use from 1980; it was privatised in 1993 and remained, by the early 21st century, one of only three privately owned coal mines still surviving in the South Wales coalfield, employing around seven men by 2001 and producing some 200 tonnes of coal a week while managing significant water and gas issues underground. On 15 September 2011, seven miners were working with explosives on a narrow coal seam when a controlled blast, intended to breach into a separate disused and flooded mine network to improve ventilation, instead released around 650,000 gallons of water into the tunnel. Three miners escaped, one with life-threatening injuries; the remaining four -- Charles Breslin, 62, David Powell, 50, Philip Hill, 44, and Garry Jenkins, 39 -- were trapped roughly 90 metres underground. A major rescue operation, involving Mid and West Wales Fire and Rescue Service and mines rescue units drawn from across the United Kingdom, found all four dead the following day, 16 September. Parallel investigations by South Wales Police and the Health and Safety Executive followed; mine manager Malcolm Fyfield was arrested in October 2011 and charged in January 2013 with four counts of manslaughter by gross negligence, and the operating company, MNS Mining Ltd, was charged with corporate manslaughter. Both were acquitted at trial on 19 June 2014. A coroner later found there was 'more than a suspicion' that safety regulations had not been followed at Gleision for over a decade, and a full inquest was still being pursued more than a decade after the disaster.

Workings

A small drift mine (not shaft-worked) on the shallow, 2 feet 6 inch Ynisarwed seam, worked in its final years by a workforce of around seven men producing roughly 200 tonnes a week.

Closure

Working ended after the 15 September 2011 flooding disaster, which killed four of the mine's seven-man underground team.

What remains

No reliable current-condition detail specific to the site has yet been located beyond its role as the site of the 2011 disaster.

Related mines

• Tarenni Colliery — Gleision worked the same Tawe valley coalfield as the much larger, long-closed Tarenni Colliery, and is its modern, much smaller successor working in the district.

Disasters & major incidents

• Gleision Colliery Flooding, 2011
  15 September 2011 · Flooding / Inundation · 4 fatalities
  Four miners drowned at the small drift mine Gleision Colliery when a controlled blast, intended to breach into disused flooded workings for ventilation, instead released around 650,000 gallons of water into the tunnel where seven men were working -- the worst mining disaster in Wales in three decades.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• Gleision was one of only three privately owned coal mines still surviving in the South Wales coalfield by the early 21st century, employing around seven men and producing roughly 200 tonnes of coal a week. ¹
• On 15 September 2011 a controlled blast intended to breach into disused flooded workings for ventilation instead released around 650,000 gallons of water into the tunnel, trapping four miners roughly 90 metres underground; all four were found dead the following day. ²

Photographs & further reading

Sources

1. (secondary) Tarenni Colliery — Wikipedia
2. (secondary) Gleision Colliery mining accident — Wikipedia

Record created: 2 September 2026 · Last researched: 2 September 2026