Aberfan disaster

The Aberfan disaster (Welsh: Trychineb Aberfan) was the catastrophic collapse of a colliery spoil tip on 21 October 1966. The tip had been created on a mountain slope above the Welsh village of Aberfan, near Merthyr Tydfil, and overlaid a natural spring. Heavy rain led to a build-up of water within the tip which caused it to suddenly slide downhill as a slurry, killing 116 children and 28 adults as it engulfed Pantglas Junior School and a row of houses. The tip was the responsibility of the National Coal Board (NCB), and the subsequent inquiry placed the blame for the disaster on the organisation and nine named employees.

There were seven spoil tips on the hills above Aberfan; Tip 7—the one that slipped onto the village—was started in 1958 and, at the time of the disaster, was 111 feet (34 m) high. In contravention of the NCB's procedures, the tip was partly based on ground from which springs emerged. After three weeks of heavy rain the tip was saturated and approximately 140,000 cubic yards (110,000 m³) of spoil slipped down the side of the hill and onto the Pantglas area of the village. The main building hit was the local junior school, where lessons had just begun; 5 teachers and 109 children were killed.

An official inquiry was chaired by Lord Justice Edmund Davies. The report placed the blame squarely on the NCB. The organisation's chairman, Lord Robens, was criticised for making misleading statements and for not providing clarity as to the NCB's knowledge of the presence of water springs on the hillside. Neither the NCB nor any of its employees were prosecuted and the organisation was not fined.

The Aberfan Disaster Memorial Fund (ADMF) was established on the day of the disaster. It received nearly 88,000 contributions, totalling £1.75 million. The remaining tips were removed only after a lengthy fight by Aberfan residents against resistance from the NCB and the government on the grounds of cost. The site's clearance was paid for by a government grant and a forced contribution of £150,000 taken from the memorial fund. In 1997 the British government paid back the £150,000 to the ADMF, and in 2007 the Welsh Government donated £1.5 million to the fund and £500,000 to the Aberfan Education Charity as recompense for the money wrongly taken. Many of the village's residents developed medical problems as a result of the disaster, and half the survivors have experienced post-traumatic stress disorder at some time in their lives.

Background

Aberfan is situated toward the bottom of the western valley slope of the Taff Valley, on the eastern slope of Mynydd Merthyr, approximately four miles (6 km) south of Merthyr Tydfil. When the Merthyr Vale Colliery was sunk on 23 August 1869 by John Nixon and partners, Aberfan consisted of two cottages and an inn frequented by local farmers and bargemen. By 1966 its population had grown to approximately 5,000, most of whom were employed in the coal industry. Since the nationalisation of the British coal industry in 1947, Aberfan's colliery had been under the control of the National Coal Board (NCB). Regulation in the coal industry was provided by HM Inspectorate of Mines. The inspectors had worked as engineers in the coal industry and were former employees of the NCB. The River Taff runs north-to-south through the village; at the upper side of the settlement, on the western outskirts, the bed of the disused Glamorganshire Canal and a disused railway embankment run parallel to the river.

The first spoil from the coal mine was deposited on the valley's lower slopes, east of the canal, but during the 1910s the first tip was started on the western slopes, above the canal line and the village. By 1966 there were seven spoil heaps, comprising approximately 2.6 million cu yd (2.0 million m³) of waste. Tips 4 and 5 were conical mounds at the apex of the slope, although Tip 4 was misshapen from an earlier slip; the remaining five were lower down; all were directly above the village. Tip 7 was the only one being used in 1966. About 111 feet (34 m) high, it contained 297,000 cubic yards (227,000 m³) of spoil, which included 30,000 cubic yards (23,000 m³) of tailings—waste from the chemical extraction of coal, fine particles of coal and ash which took on properties similar to quicksand when wet.

Tip stability is affected by water conditions. Tips 4, 5 and 7 had been sited on streams or springs. The presence of the springs was common knowledge in the area, and they had been marked on the Ordnance Survey and Geological Society maps since 1874. Tip 4 at Aberfan, which had been used between 1933 and 1945, was large, and had been started on boggy ground between two streams. At the time of its planning, the Merthyr Tydfil borough engineer thought that despite the position, it would be unlikely to avalanche. Following some ground movements in the tip in the early 1940s, a drainage channel was dug in early 1944. In November that year part of the tip slid 1,600 feet (490 m) down the mountain to stop approximately 500 feet (150 m) above the village. In May 1963 Tip 7 shifted slightly; in November that year there was a more substantial slide. The NCB stated that the movement had not been a "slide", but was instead a "tailings run"—a run-off of tailings from the surface of the tip—which left its stability unaffected. After the slide, the NCB stopped tipping tailings on number 7, but normal spoil continued to be deposited.

Aberfan is in an area of relatively high rainfall, an average of 60 inches (1,500 mm) a year. In 1960 it was 70.5 inches (1,790 mm), the heaviest of recent years in the run-up to the disaster. Between 1952 and 1965, there was severe flooding in the Pantglas area of Aberfan on at least 11 occasions. Residents complained that the flood water was black and left a greasy residue when it receded. Complaints had been made by residents to Merthyr Tydfil County Borough Council, who corresponded with the NCB between July 1963 and March 1964 on the topic of the "Danger from Coal Slurry being tipped at the rear of the Pantglas Schools". In early 1965 meetings were held between the council and the NCB at which the Board agreed to take action on the clogged pipes and drainage ditches that were the cause of the flooding. No action had been taken by October 1966 when the tip collapsed.

Tip collapse

During the first three weeks of October 1966 there were 6.5 inches (170 mm) of rainfall, nearly half of which was in the third week. During the night of 20–21 October the peak of Tip 7 subsided by 9–10 feet (2.7–3.0 m) and the rails on which the spoil was transported to the top of the tip fell into the resulting hole. The spoil movement was discovered at 7:30 am by the first members of the morning shift manning the heaps. One of the workers walked to the colliery to report the slip; he returned with the supervisor for the tips, and it was decided that no further work would be done that day, but that a new tipping position would be decided on the following week.

At 9:15 am a significant amount of water-saturated debris broke away from tip 7 and flowed downhill at 11–21 miles per hour (18–34 km/h) in waves 20–30 feet (6.1–9.1 m) high. G. M. J. Williams, a consultant engineer who gave evidence at the subsequent tribunal, stated that the 9:15 am movement:

took part of the saturated material past the point where liquefaction occurred. This initially liquefied material began to move rapidly, releasing energy which liquefied the rest of the saturated portion of the tip, and almost instantaneously the nature of the saturated lower parts of Tip No. 7 was changed from that of a solid to that of a heavy liquid of a density of approximately twice that of water. This was 'the dark glistening wave' which several witnesses saw burst from the bottom of the tip.

Approximately 140,000 cubic yards (110,000 m³) of spoil slid 700 yards (640 m) down the mountain, destroying two farm cottages and killing the occupants. Around 50,000 cubic yards (38,000 m³) travelled across the canal and railway embankment and into the village. The flow destroyed two water mains buried in the embankment and the additional water further saturated the spoil. Those who heard the avalanche said the sound reminded them of a low-flying jet or thunder.

The avalanche struck Pantglas Junior School on Moy Road, demolishing and engulfing much of the structure and filling classrooms with thick mud, sludge and rubble; 109 children, from 240 attendees, and five teachers were killed in the school. The pupils of Pantglas Junior School had arrived only minutes earlier for the last day before the half-term holiday, which was due to start at 12 midday. The teachers had just begun to record the children's attendance in the registers when the landslide hit. The adjacent secondary school was also damaged, and 18 houses on surrounding roads were destroyed. Mud and water from the slide flooded other houses in the vicinity, forcing many to evacuate their homes. Once the slide material had come to a halt, it re-solidified. A huge mound of slurry up to 30 feet (9.1 m) high blocked the area. The acting headmaster of the secondary school recalled: