31 August 1998 00:00 [Source: ICB]
Estarreja has a long history in the production of petrochemicals, ranging from intermediates to plastics, chlorine, PVC, industrial gases, isocyanates, nitric acid and fertilisers.
However, for over 50 years the chemical industry here has failed to treat solid and waste discharges. In fact until the mid-1980s industrial hazardous wastes were disposed of without any consideration to the environment and nearly 500 000 tonne of hazardous waste was dumped in different locations on the Estarreja complex. Contamination from heavy metals and organic compounds has eventually spread outside the chemical perimeter, reaching the ground water and waterways in the populated area and as a result shallow water wells have become contaminated and have been abandoned.
A remedial investigation carried out by the local authorities and Portuguese government identified three different contaminated areas. Residues from the Cires complex, originating from the production of acetylene, which is no longer produced, were found to total 320 000 tonne of calcium hydroxide and occupy an area of 90 000m2. An additional 150 000 tonne of residues, originating form the production of sulphuric acid and fertilisers from the former Quimigal operations, have been identified in a 30 000m2 area. These comprise pyrite cinders contaminated with heavy metals, in particular, zinc, lead arsenic, copper, iron, oxides and sulphates. In a third area of 20 000m2 in size, around 100 000 tonne of mercury waste from the production of chlorine and caustic soda from the Uniteca operations was identified. Recommendations were made in the remedial investigation to carry out a preliminary project to remove the accumulated wastes, the contaminated soils and to regenerate the contaminated groundwater.
In 1997, a public tender was launched with the authorisation of the Ministry of Finance, and the Ministry of the Environment and Natural Resources. The selected company submitted a preliminary report which was discussed by all of the interested parties and a final report was drawn up , establishing all the steps needed to treat the waste and recovering the soil where the waste had been deposited.
As far as the Cires site is concerned this will involve the reintegration of its calcium hydroxide lime deposit into the landscape and the sealing of the former landfill in order to avoid any future leaching into the soil. The wastes of the Uniteca complex must be put in a separate cell of a secure landfill to be demecurised later on in a special installation to be constructed using a process developed by Lisbon University. Meanwhile, the pyrite residues, after mixing with lime, are also to be deposited in a secure landfill.
The petrochemical companies located on the Estarreja complex are now in the process of setting up a company for the environmental recovery of the contaminated soils. As part of the project, entitled ERASE, companies sited at the Estarreja complex will become shareholders of the new venture.
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