Abstract: Sfax, a coastal city open on the Mediterranean, is the second industrial town of Tunisia. It is the most important industrial and commercial center of the South of the country. Many food and chemical industries are installed on its territory, notably the chemical industry units specialized in phosphate transformation and fertilizer production. The fertilizer industry produces phosphoric acid by treating natural phosphates with the sulfuric acid

while generating important quantities of phosphogypsum and the acid. The factory of phosphoric acid production NPK, which existed during the period between 1963 and 1991, anarchically discharged enormous quantities (some 6 million m3) of phosphogypsum into the northern coasts of Sfax. Hence, It has contributed, in addition to the neighbouring industries that have been gradually installed in the contiguous area (powder store), to the degradation of the human and natural environments. This factory was then closed in October 1991 to put an end to the principal source of pollution in the area.

Although NPK was closed and several closely related actions were undertaken in the area, the industrial activities have left a heavy heritage. Besides the degradation of the natural environment, an enormous phosphogypsum deposit, occupying some 50ha surrounded by a phosphogypsum plate spanning over 80ha, still remains the great threat to the area ground and marine waters pollution. The threat is caused by the acidity of the leachates, the high concentrations of heavy metals and other polluting elements and compounds that the phosphogypsum can release. Besides chemical pollution, this 8m-high deposit has a very disadvantageous visual impact on the city; especially that it is located near the town centre.

In this respect, the objective of Taparura project is to transform the northern coasts of Sfax, affected by industrial wastes, to an urban neighbourhood where it is nice to live and where all the pollution sources are eradicated or neutralized.

Moreover, this project will allow the city to reconcile with its littoral thanks to the creation of 3km artificial beaches and a new urban area of 450ha gained from the sea to extend the hyper-center of Sfax to better reinforce and develop it. Developing this extension is planned in areas of leisure and housing, commercial activities and services, parks and public equipments. 

However, taking into consideration the scale of this project, it was decided to carry it out stage by stage. The first stage consists in controlling all pollution sources, which could threaten the coastal area environment in the future.

The project cleaning up stage includes the following works:

• Excavation of the phosphogypsum plate which skirts the deposit (2 million m3 on 90ha).
• Scouring the polluted ground and marine materials (400ha- average thickness 0.4m)
• Developing the deposit to a green area in the form of a 15m-high cone trunk (the upper circle radius: 361.5m -the base circle radius: 439m - slope 1/5).
• Isolating and covering the phosphogypsum deposit (surface: 72ha - perimeter: 3,200m).
• Setting up a pumping system inside the deposit (flow 2 l/s)
• Depositing works (7.450 million m3 including 6.150 m3 of marine origin).
• Cost protection and drainage worksThe above-mentioned works allow for gaining ground from the sea after depositing.

The project second stage concerns the area’s viability (development works).

For this purpose, a development plan was chartered and approved. This plan draws the following development

program of the urban centre of Taparura :