ICMM - International Council on Mining & Metals

CASE STUDY

Lessons from a tailings dam failure

In 1998, the tailings impoundment at Boliden Apirsa’s mine in southern Spain was breached, resulting in the release of a flood of tailings and supernatant water. The tailings flowed down the natural river system, affecting 4634 hectares of land along 40 kilometres of riverbank and farmland, of which 2600 hectares were covered by tailings, with the flow threatening the Doñana National Park 50 kilometres to the south. The impoundment contained 15 million cubic metres of tailings at the time of the incident. Within a few hours of the breach developing in the dam wall, an estimated 5.5 million cubic metres of liquid and 1.7 million cubic metres of solids were released. When the water level fell, the depth of deposited tailings ranged from 4 metres near the tailings impoundment to a few millimetres 40 kilometres downstream.

The flow followed the course of the Rio Agrio and Rio Guadiamar and reached the marshlands on the eastern edge of the Doñana National Park some seven or eight hours later. In the marsh area to the east, a system of dikes and canals were built to reroute the river into the Brazo de la Torre, which then flows into the Rio Guadalquivir. The Rio Guadiamar is in its lower stretch converted into a main irrigation canal, known as the Entremuros, that separates the reclaimed agricultural land to the west from the rice paddies to the east. Here the flow was partially stemmed by a series of dikes that were hastily constructed along the Entremuros by staff from the National Park with the help of rice farmers in the area. The damming up of the Entremuros prevented the contaminated water from reaching the Doñana park area.

The immediate and potential long-term effects were severe. The water and tailings affected more than 50 irrigation wells on the river floodplains, and aquatic life in the rivers was depleted. The spill-affected farmland was used for grazing, agricultural crops and fruit plantations and included important sites for migratory birds. Spanish authorities banned all use of wells and produce in and from the affected land. Boliden Apirsa bought the harvest of fruit for the season to minimize effects on the farmers and to ensure that no contaminated fruit reached the marketplace.

A cleanup plan was presented to the authorities three days after the incident. The company objective was to return the land fully to its previous use. The government,however, wanted to restore the area to an earlier, pre-mining condition and to create a natural park. Following two days of negotiations, responsibilities were divided between the mine and the local authorities. The tailings were mechanically removed and trucked to the old Aznalcóllar open pit for disposal. While haul roads were used alongside the river, public roads also had to be used, and there were five fatal road incidents during the cleanup operation.

Prior to the incident, the relationship between the mine and the authorities (Regional Government of Andalusia, the Guadalquivir River Authorities and the Spanish Geological Survey) were good. One year before the incident the mine operator, with the support of the Aznalcóllar local community and the authorities, completed a significant investment programme that included the building of a new concentrator and the development of a new open pit. (Even after the incident the relationship remained good, in spite of the difficult situation; a joint committee was formed to manage the situation, with Boliden and various relevant authorities represented.) Communication with the administration of the Doñana National Park had not been established before the incident, however. Because of the 50 kilometres distance from the operation, establishing a dialogue had not been identified as necessary.

At the time of the incident, there were no legal requirements for the operation to have an Emergency Plan, and corporate policy was still being developed. In 1997 Boliden had started to develop operation, supervision and maintenance manuals for the company’s tailings storage facilities, which included Emergency Plans. When the incident occurred the manual had not been completed for the Apirsa operations, as a recently performed safety audit had not identified this as a priority.

Apirsa’s response to the incident was to be honest, open and factual and to refrain from speculating when dealing with the authorities, the mass media and the local community. Three weeks after the incident the company opened an information centre in a nearby village, providing information on what had happened and what was happening in the cleanup operations. But the centre failed to attract many visitors. Despite the seemingly poor response, the good work done in providing information had a beneficial return. When rumours later emerged that Boliden was going to pull out of the operation, the local community demonstrated in favour of reopening of the mine, but with renewed and more stringent operating parameters.

Observations

The actions of the staff of the Doñana National Park, with the help of the rice farmers, limited the impact of the incident.

The lack of an Emergency Plan addressing this particular situation meant that cleanup responsibilities and objectives were established after the event and under intense political and media pressure.

The media had preconceived ideas about the company, which meant that reporting was rarely objective.

The lack of good-quality baseline data made it difficult to evaluate the effects of the incident and subsequent level of rehabilitation.

The absence of cleanup criteria and differences in objectives led to uncertainties.

The most effective information channel with the community was through employees.

A computerized document register would have saved significant time and effort.

Analysis

The incident highlighted the importance of having relationships in place before something happens, in order to build trust between parties and to establish roles and responsibilities, action plans and so on.

The need for internal and external information cannot be overestimated. Significant resources have to be allocated to dealing with the mass media.
The company’s own judgement is that an even more proactive position in providing information to the local community would have been beneficial.

The need to provide employees and the relatives to these directly involved, who are under great stress at such times, with support as well as information must be addressed.

Cleanup operations carry their own risks. The large logistical operation that may be required to deal with the aftermath of major incidents may itself necessitate a degree of risk assessment, emergency planning and community communication.