National Coal Board specialists are now fairly certain that a mountain spring welling up inside the Aberfan coal tip caused the avalanche that wiped out a generation of schoolchildren here on Friday.
At the latest count late tonight, 137 bodies had been taken from the school and from the remains of 11 demolished cottages. More bodies were expected to be recovered from the buried houses. The Chief Constable said he feared all hope had to be abandoned for those still missing ╤ 51 children and an unknown number of adults. It was estimated that about 50 more bodies might still be recovered, taking the total to more than 180.
At the public inquiry, which will be held in Merthyr Tydfil by Lord Justice Edmund Davies, the National Coal Board will be faced with two questions:
1. Why did they continue tipping coal dust onto a powerful source of water?
2. Why, after giving a written assurance to the Merthyr Tydfil borough council in 1964 that tipping at Aberfan would cease, did they change their minds and start again?
Lord Robens, chairman of the National Coal Board, revealed the presence of the spring in a television interview last night. He said:
╥We have discovered water welling up in the virtual centre of the tip ╤ a natural spring which was completely unknown. This spring has been pouring its water into the centre of the tip producing what an official has described as a water bomb.
╥In the view of the NCB this is the cause of the slip, but as there is to be an inquiry we will simply give the evidence as we know it. Men have been working day and night doing irrigation work. They have reached the hub of the spring and by means of trenching and piping have diverted its course.╙
It is not yet known whether the spring was there on the Aberfan mountain before the coal tip was put down anything from 30 to 50 years ago. But there are believed to be people still living in the village who say it was.
Whichever is the case, the board is bound to be asked at the inquiry ╤ findings of which will be published by the Secretary of State for Wales, Mr Cledwyn Hughes ╤ why its 1964 investigations did not reveal the spring.
Evidence and viewpoints obtained by the board today indicate that the coal tip ╤ perched 800 feet above the village ╤ collected thousands of gallons of water. Then, swelled by the stream at its base, and last week╒s torrential rain, it must have burst like a bubble.
Merthyr borough council is known to have received many letters of complaint, either about flooding from the tip, or of some imagined danger to the village. ╥They dreaded it,╙ as one man who knows the village well said today.
