INCIDENTS

Los Frailes - Tailings Dam Failure, Spain, April 1998

NEWS:

BACKGROUND:

On April 25, 1998, a tailings dam failure of the Boliden Los Frailes lead-zinc mine at Aznalcóllar, Spain near Seville, released 6.8 million cubic meters of acidic tailings slurries and liquid into natural river systems the nearby Río Agrio, a tributary of the Río Guadiamar. The slurry wave containing sulphur, zinc, copper, iron, lead and other trace elements inundated several thousand hectares of farmland, and threatened Doñana National Park, situated 50 km to the south.

A slab of soil beneath the dam slid approximately one metre towards Río Agrio. The front of the slide was about 20 metres wide, and it was located in the area of the junction of the two impoundments. The dam cracked and broke abruptly; the wall collapsed and swept along the separation dam between the two impoundments. Between five and seven million cubic metres of contaminated water and slurries spilled through the gap. The bed of Río Agrio rose three metres, changing its course and bringing Tertiary rocks to light.

TYPE OF INCIDENT:

• Dam foundation failure.

• Release of 6.8 million m³ of acidic slurries and liquid.

IMPACTS:

• Inundation of up to 2,000-3,600 ha of farmland.

• Massive fishkill and destruction of aquatic species in the river system as well as threatening Doñana National Park.

• Loss of 5,000 jobs in agricultural, fishing, tourist and nature conservation activities.

• Cleanup costs = more than 16 Billion pesetas ($135.7 Million) (by National Post Online)

Documents:

• The tailings pond failure at the Aznalcóllar mine, Spain (N. Eriksson Boliden Environmental Staff, Aznalcóllar, Spain and P. Adamek Mine Environmental Consultant, Sevilla, Spain) 114 KB

Links:

• Boliden (This site contains a number of news releases regarding the accident.)

• Mining and Environment Research Network (NERN). Boliden Apirsa, Los Frailes Tailings Incident Combined Report.

• The Los Frailes tailings dam failure (Aznalcóllar, Spain) (15 May 2000)

• Los Frailes Aftermath. Detailed investigation and July 1998 issue of Mining Environmental Management 

• Safety of Tailings Dams

• Follow-up report by Mining Environmental Management

• Report on the technical aspects of the incident and the media coverage from MERN

• List of useful web pages with more information

• The Ugly Canadian: The Philippines, Los Frailes, Spain

• Technical Issues - Tailings

Articles:

• Planet Ark

  • SPANISH MINE SPILL SITE MAY BE UNSAFE - GREEN LOBBY (26/04/02)

  • Boliden Says Court Clears it of Los Frailes Crime (20/11/01)

• National Post Online

  • Boliden Mulls Suit Over Spanish Toxic Spill (04 January 2001)

• Lycos Environment News Service

• Design Fault Blamed for Doñana Mine Spill (12/04/00)

• BBC News

• Effects of toxic spill could last 40 years (30/04/98)

• Toxic flood devastates Spanish farmland (29/04/98)

• Dam breach renews threat to Spanish national park (28/04/98) 

• Ecological disaster averted (26/04/98)

Disclaimer: UNEP DTIE makes every effort to ensure, but does not guarantee, the accuracy of the information on this web site. Hyperlinks to other web sites imply neither responsibility for, nor approval of, the information contained in those other web sites on the part of UNEP.