The complexity of safeguarding

Venetians are fully aware of their complex man-environment relationship and have always been wary in dealing with the salty sea water and the fresh water that flows from the rivers, which create the delicate balance in the lagoon. They have learned from their pragmatism, that if you want to change the eco-system, you have to experiment and proceed step by step, so that you can promptly restore the original situation, if necessary. Even more so when powerful technology can swiftly solve problems that until a few decades ago were insurmountable, but which can also cause huge damage often irreversible.

After the dramatic event in 1966, which is forecast to reoccur in 140 years time, a huge emergency plan was undertaken, which is still in progress, so we can now say that Venice is no longer unprepared and can confront other similar emergencies, without any dramatic consequences. The embankments, offshore breakwaters and the coast lines have been raised and reinforced as protection against the sea and the lagoon. The smaller islands have been protected by embankments. In the city the gas, electricity, water, telephone and optic fibre mains have been raised to a safe height. Houses built at ground level, and therefore subject to flooding, were eliminated and fuel oil is no longer used for heating.

A complex maintenance program is also underway for all the buildings built on the lagoon, called the integrated RII project, which involves digging canals, bringing the sewerage system up to standard, reinforcing the banks, bridges and foundations of the buildings on the canal, rationalization of utilities, electricity, water, gas, telephone and optic fibre services elevating the practicable levels.

Rudj Maria Todaro

Urban maintenance system manager
If we look at the pavement we can see the visible red areas which indicate the areas that flood when a high tides exceeds 120cm. The pavement levels in these areas are scheduled to be raised by the end of 2010. The Integrated RII Project has scheduled to raise all the pavement levels to 120cm. within the next 30 years. Figures show that high tides exceeding 120cm. only occur every 18 months, and the curve shows that the maximum peak lasts approximately 2 hours 20minutes.

Mario Scatolin

Biologist, technician for water Protection Hygiene
Redevelopment began in Venice in 1990 and is slowly being brought into line with new standards and legislation, but the decisive point came in 1995 when the 206/95 law was passed. Since then the council has been responsible for hygiene redevelopment and has set up approximately 6.000 plants in the historic city. Represented on the map are the various types depending on the kind of installation involved. A typical one is the three-compartment septic tank which is generally used in small buildings, with a maximum of 100 inhabitants and then there are other more complex systems, mostly used for hotels and large public buildings. These systems are much more practical and in some cases ensure that a large quantity of sewage is not discharged into the inner city canals, so that the areas can be reclaimed and the canals dug. The third step involves the so called tanks to protect private homes from the flood waters.

Alessandro Perilli

Chief technician for contributions for Private Properties
In Venice the only way buildings situated on the ground floor can be protected from the water is by tanks. The discharges are fitted with special valves that close as the tide rises and prevent the flooding of the houses or shops. To build a protection tank against the flood waters, the floor and the foundations must be demolished. A 30cm deep loose stone foundation is then laid, an electro-welded net is put into place, the anchorage for the walls, lean concrete, bentonite and the geo-fabric is positioned and then the floor can be built.

During the past 10 years 200 ground floor buildings have been rebuilt using this procedure.

Total cost 5 million Euros