Cae Glas Colliery Gassing, 1958

The mine's owner and two workmen were asphyxiated by gas while checking the water level in old, disused workings beyond the active faces at this small licensed drift mine.

Cause

The licensee periodically entered the old level beyond the mine's active workings to check the water level, which varied with the weather; the level inbye was flooded. On 24 September 1958 he went in with two workmen and all three were overcome by gas before they could get out.

What happened

Cae Glas Colliery had been reopened in 1955 as a small National Coal Board-licensed mine worked by the Shankland family of Fochriw, developing the south drift off the main level of the much older 1920 GKN workings. The active workings were set off this main level, which continued on beyond them for a considerable distance into ground that was no longer worked. That old, disused stretch was flooded, with a water line that rose and fell with the weather. From time to time the licensee went in beyond the active workings to see where the water stood. On 24 September 1958 he made that check accompanied by two workmen, Wilfred and Charlie Hollister. All three were overcome before they could withdraw. One published account names the cause as gassing by methane; the fuller account, from the Northern Mine Research Society's survey of the district's small collieries, is explicit that the three were overcome with blackdamp — the oxygen-starved, carbon-dioxide-rich atmosphere that commonly stagnates in old, sealed-off workings — while trying to determine the water's extent.

Investigation & inquiry

Unknown.

Related terminology

Mining terms this disaster is structurally linked to, with the nature of the relationship.

• Chokedamp (direct cause)
  Both sourced accounts of this incident describe the gas encountered in the old, flooded workings as blackdamp (one names it methane instead); Chokedamp is the term page's own heading, with Blackdamp recorded there as its standard alias.
• Colliery (contextual relationship)
  Named twice in this record, first in the narrative: “Cae Glas Colliery had been reopened in 1955 as a small National Coal Board-licensed…”
• Drift (contextual relationship)
  Named in this record’s summary: “…old, disused workings beyond the active faces at this small licensed drift mine.”
• Level (contextual relationship)
  Named 4 times in this record, first in the cause: “The licensee periodically entered the old level beyond the mine's active workings to check the water level, which…”

Sources

1. (secondary) Cae Glas — Welsh Coal Mines
2. (secondary) Small Collieries of the Tredegar area — Northern Mine Research Society

Record created: 15 September 2026 · Last researched: 15 September 2026