1. Enviromental Geotechnology Disaster of Aznalcóllar (SPAIN) When? April 25th 1998 Where? Aználcollar -near Seville (SPAIN ) What? A dam failure of “Los Frailes” lead-zinc mine released. between 4 and 5 million cubic meters of toxic tailings slurries and liquid. Why so important? Because it happened near the largest. Nature reserve in Europe “Doñana ”.

2. Enviromental Geotechnology Disaster of Aznalcóllar (SPAIN) THE CAUSES OF THE DAM FAILURE 1-The slab of soil moves 2-The junction wall-dam breaks 3-The dam collapses 4-Contaminated water and slurries spilled through the gap

3. Enviromental Geotechnology Disaster of Aznalcóllar (SPAIN) WHY DID THE SOIL MOVE? GeodisaadviseGeodisa in 1996 advise : “We have found a weak point!!” Chemical attackChemical attack acidic pyretic slurries were attacking the dam foundation material. Expansive claysExpansive clays Subsoil unsuitableSubsoil unsuitable to support the mass of tailing piled up.

4. Enviromental Geotechnology Disaster of Aznalcóllar (SPAIN) EPTISA EXPLANATION

5. Enviromental Geotechnology Disaster of Aznalcóllar (SPAIN)

6. Enviromental Geotechnology Disaster of Aznalcóllar (SPAIN) CONSEQUENCES OF THE SPILLAGE Damage to Doñana’s wildlife: Damage to farms and companies in the area: Damage to inhabitants and villages near Doñana: Aquifers Animals (it will affect fertility and immune system) Plants Crops were destroyed Fishing industry in the area was affected Water supplies Humans could be affected (food chain )

7. Enviromental Geotechnology Disaster of Aznalcóllar (SPAIN) STRATEGIES TO SOLVE THE SPILLAGE SHORT TERM Measures 1) Extract the sludge 2) Treat the polluted water 3) Inmobilisation of the heavy metals in the soil Aims 1) Preventing health risk. 2) Minimising the environmental socio-economic impact.

8. Enviromental Geotechnology Disaster of Aznalcóllar (SPAIN) LONG TERM Aims 1) Restore the lost function of Guadiamar river. 2) Improve the quality of life of the inhabitants of the river. STRATEGIES TO SOLVE THE SPILLAGE (CONT)

9. Enviromental Geotechnology Disaster of Aznalcóllar (SPAIN) Before the regeneration and reforestation soil correction activities were carried out: AFTER THE CLEANING-UP OPERATIONS Physical removal of contaminants. Calcium carbonate treatments. Addition of iron clayey materials. Phyto-remediation.

10. Enviromental Geotechnology Disaster of Aznalcóllar (SPAIN) DOÑANA NATIONAL PARK TODAY Correction actions have been effected. Try to recover all the waste is impossible and pollutants will continue within the area for many decades. HOWEVER