The Aberfan Disaster

1
The Aberfan Disaster

• Josh Gaskin Michael Sataya

2
Aberfan Spoil Slip

• Taff Valley, South Wales

• Complex of colliery waste
• 21st October 1966
• 455,000 tonnes slid
• 144 people killed

3
Local Geology

• Solid Geology
• Pennant Coal Measures
• Drift Geology
• Glacial deposits
• Hydrogeology
• Sandstone aquifer

4
Spoil Failure

• Three phases
• Phase 1 rotational slip
• Phase 2 flow slide
• Phase 3 mud run

5
Engineering Solutions

• Improved drainage
• Reduces the undue accumulation of
  water in the ground
• Alleviates the problem of material liquefying
• Improves stability of the tip

6
Engineering Solutions

• Diversion Walls
• These divert the flow away from the areas at risk

7
Engineering Solutions

• Diversion Walls

8
Engineering Solutions

• Retaining devices to stabilise slopes
• Dense compaction to improve ground stability
• Regrading of slopes to prevent over-steepening

9
Action Taken

• Improved design of tips
• Factor of safety of 1.5 for the slopes where
  people and property are at risk
• Factor of safety of 1.25 where no people or
  property are at risk
• Improved drainage of tips
• Bored filter drains
• Relief wells
• Adits

10

• Thank you for listening!