Excursion 1

Visit of the «Green Corridor» of the Guadiamar (Sevilla)

In the frame of this excursion, we will visited selected places of the so-called “Green-Corridor” of the Guadiamar, which was initiated as results of the clean-up efforts at the shores of the River Guadiamar after the tragic mining accident of Aznalcóllar in 1998. We will visit different places, which were affected by the mine spoils and treated by different remediation and restoration strategies. A visit of the surrounding of the former mine as well as an experimental station is also included. At the end of the tour, a lunch (not included in the fee) is planned to take place in a nice restaurant, in the Sierra de Aznalcóllar.

The mining accident of Aznalcóllar

During the morning of the 25th of April in 1998, one of the mine tailings ponds of the Los Frailes mine close to Aznalcóllar (Seville Province, Spain) bursted. About 4 to 5 million cubic metres of mine tailing, loaded with dangerous heavy metals were released and quickly reached the close-by Agrio River and its affluent the River Guadiamar. This mixture of acid waters and sludge moved about 60 km along these waterways, before it could be stop in an area, which is called “Entremuros, located at the boarder of the «Doñana National Park, a UNESCO World Heritage Site and one of the largest national parks in Europe. The construction of three walls avoided that the contamination expanded into the park or the River Guadalquivir and its rich estuarine shores. According to the Spanish Research Council (Consejo Superior de Investigaciones Científicas, CSIC), the environmental impact of this Disaster of Aznalcóllar, also known as Doñana Disaster or Guadiamar Disaster was almost 100 times higher than the impact caused by the spillage of the Prestige. The cleanup operation took three years, at an estimated cost of €240 million. As a consequence of the accident, the mine was closed leading to a loss of 2.000 work positions which had a considerable negative impact on the economy of this area.

In total 4.400 hectares along more than 60 kilometers following the riverbed of the Guadiamar, were devastated. Aside the destruction of ecosystems and plants, soils were contaminated, many of which had to be removed and cleaned up.

The creation of the Green Corridor

After the first cleanup, the ecological restoration of the affected areas started, leading to the creation of the Green Corridor of the Guadiamar.

For the remediaion of the soils, compost and amendments were applied to support immobilization of the metals. Other means comprised reforestation with autochthone species typical of river shores and Mediterranean forests. 

Many of those remediation efforts were scientifically monitored during the 20 years since the accident (about 435 publications in indexed journals).  Thus, aside from demonstrating the sites, the intention of this excursion is to discuss some of the obtained results related to success or failure of the applied decontamination strategies.