The entire area has been subjected to environmental characterization carried out by ICRAM (today ISPRA) in compliance with the Environmental characterization Plan compiled by such Agency (ref. ICRAM CII-Pr-Pu-T-IV Sporgente e darsena ad ovest) and its subsequent revision document (Ref. ICRAM CII-Pr-Pu-T- IV Sporgente e darsena ad Ovest) which endorsed the dispositions of the planning conference by local authorities.
The characterization results have then been analyzed using Geostatistical methods. In particular, in regards to the sea works, studies regarding the basement depth of the Pleistocene blue clays and of their different dimension portions together with the sea floor’s bathymetry and contaminants concentrations at different depths.
Thanks to this processing, a man-caused random pollution situation has been highlighted and it appears clear that the contamination reaches a maximum depth of 2m and can be definitely ascribed to both organic and inorganic contaminants. Organic pollution has been found only in the upper layer (0-50 cm) and is related to Polycyclic Aromatic Hydrocarbons. Hot spots have been found in the southern area of the future quay area, with an environmental concentration up to one order of magnitude higher than the standard value. Inorganic pollution involves deeper areas (up to 2 m depth) and a wider surface area.
No microbiological contamination (fecal streptococci, salmonella, clostridia Sulfate-reducing spores) has been found, while toxic effects caused by less toxic contaminants have been widely reported in the central area of study, located further away from the infrastructures and at a greater bathymetry.
In view of the results achieved, sediments have been divided in three categories:
– “red” sediments; their volume is defined by using Table 1, column B of Attachment n. 5, Section 4 of the Decree n. 152/06;
–“yellow” sediments; with concentrations above the standard limit values defined by ICRAM, but lower than the ones in Table 1, column B of Attachment n. 5, Section 4 of the Decree n. 152/06;
–“green” sediments; with concentrations lower than the alarm ones defined by ICRAM.
The environmental remediation plan complies with the aims defined by ICRAM, and involve the dredging and treatment of sediments that were found to be contaminated as a result of the environmental surveys carried out.
As a first step and before the realization of any of the planned works, the remediation plan will involve the complete removal of “red” sediments as a safety setting procedure.
Afterwards, the sea bottom will be reclaimed for all the areas in which concentrations of contaminants were found to be above “alarm values” specifically defined by ICRAM for the National Remediation Site of Taranto (“yellow” sediments).
The environmental remediation project is therefore considered as an emergency safety setting procedure in regards to “red” sediments and as a remediation procedure in the case of “yellow” sediments.
On the basis of ICRAM’s elaborations, three main remediation areas have been defined for “red” sediments; a total volume of 9,187 sq. m., including an extra 25% so to take into account possible dredging errors, has been calculated, as a precautionary measure, by considering the quantile value of the 10% of the blue clay’s height (considered as non contaminated), that is equal to the probability of the depth of the clay’s depth is underestimated is less than 10%.
In the same way, the final volume of the sediments which must be dredged is of 360,000 sq. m. and are characterized by contaminants’ concentrations which are above alarm levels defined by ICRAM but lower CLA-IND values defined in Decree n. 152/2006 (“yellow” sediments).
For “red” sediments which have been contaminated, the strategy of the emergency safety setting is the following:
• mechanical dredging of the confined areas using mobile floating booms;
• transport to the on-land treatment area using motor hoppers;
• remediation treatment using a separation and washing unit of the gravel part, followed by two hydro cyclones which will separate the sand from fine materials;
• mechanical thickening by compartment-type filter press;
• determination of the final destination of the treated materials.
In particular, the washed gravel and sand portion may be used in compliance with current regulations and used as replenishment material for the sediment tank. As the result of these treatments, contaminants will be mostly concentrated in the fine dehydrated portion and will therefore be dismissed to a authorized landfill facility which will be chosen depending on the contamination level determined in compliance with current regulation standards.
In order to verify remediation results, a monitoring procedure regarding the environmental compartments which have been directly or indirectly involved in the works will be also carried out.