About Mine Water and Acid Mine Drainage

The diagram below shows the reaction which takes place as a result of flooding mines, which can lead to the formation of acid mine drainage.

Within the last thirty years or so as coal production in the UK has reduced so have the underground pumping arrangements. This cessation has allowed underground water levels to rise and outbreaks to occur at the surface.

• The top three boxes in the diagram show how minewater is oxidised through the process of mining.
  
  
• Once the minewater reaches the surface it comes into contact with the air and a chemical reaction takes place changing the iron in the water from Ferrous to Ferric state.
  
  
• This causes small particles of iron (ferric hydroxide) to form from the solution, more commonly known as ochre.
  
  
• The photograph shows the obvious visual effect of the minewater on a natural watercourse.
  
  
• In the UK, many of the coalfields contain a significant amount of limestone which neutralizes much of this acidity, and therefore the term 'minewater' is more appropriate than 'acid mine drainage'.