FCC begins work on Spainís largest decontamination project

Posted: Tuesday 23rd April 2013

Flix reservoir is contaminated with 1 million m3 of toxic waste dumped into Spainís longest river (Ebro).

FCC, Spainís leading environmental services and infrastructure group, has begun work on decontaminating the Flix reservoir on the Ebro River (Spainís longest river) in Tarragona, Catalonia. The project represents one the largest decontamination projects in Spain in recent years, removing up to 1 million m3of contaminated river sediment Ė a revolutionary effort to reverse more than a century of pollution. The pollution arises from toxic waste dumped into the Ebro by a local chlor-alkali plant which began operating in 1897. It is estimated that the project will take two years and eight months to complete.

The project was awarded to FCC in 2008 by Acuamed (a company owned by the national government and operated by the Ministry of the Environment). No other project in the world is this huge in scope, with the same innovative features and strict safety rules. The project goals are to extract, treat and eliminate the contaminated sludge and subsequently restore the Ebro River and its ecosystem. FCC is responsible for constructing, operating, and dismantling the plant following the completion of the clean-up.

The project hopes to prevent a potential threat to the water supplies of municipalities downstream, as well as the nearby protected Sebes natural reserve. A fully equipped analytical laboratory has been set up to track the work throughout all its different phases, an essential part of monitoring the effectiveness of the work being done. The Flix project shows how even deep and long-established contamination can be cleaned up with the right application of technology and project expertise.


The 165-million-euro Flix Reservoir decontamination project draws 30% of its funds from the Spanish government and 70% from the European Union Cohesion Fund. There is also a Land Restitution Plan associated with the project, aimed at providing compensation for the people affected by the work. This associated plan entails another 57 million euros investment, split between the national government (36 million) and the Catalan government (21 million), making for a total investment of over 200 million euros, the biggest investment ever for a decontamination project in Spain, according to the Ministry of Agriculture, Food and the Environment.

Decontamination process

The sludge will be removed and treated in a process that will result in the restoration of the river water to its natural condition. The first step taken was to create a safe treatment location. A 1.3 kilometre-long double wall containment barrier was built to separate the worksite from the riverbed. The worksite was further isolated with the construction of a secant pile wall on the right bank.

Current developments

The latest stage will see the extraction of about 960,000 cubic metres of sludge contaminated with heavy metals, organochlorides and a certain amount of radioactive elements. This sludge has built up along approximately 1,100 metres of factory wall and extends some 150 metres out into the river. It will be removed by an ecological dredging procedure and treated in the plants that have been set up nearby.

The treatment process will begin with wet sorting, where the materials will be separated and classified. Next the silt will be dehydrated. This dried material will be shipped to a warehouse where it will be stored and analysed so the appropriate treatment can be determined. Meanwhile, all the water dredged out of the river and extracted during the treatment process will go to a water treatment plant, after which it will be returned to the protected area. Eventually all the material will be shipped to a landfill 8 kilometres away that has been built specifically for this project.


The safety of the local population has been ensured by: the safety measures set in the project design, a series of regular checks run by the Ebro River Hydrographic Confederation and the Catalan Water Agency, and lastly by the emergency plan agreed on 14 February 2013 by the civil protection authorities.

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