Although by their very nature underground structures have little impact on the environment, their realization nonetheless requires precautions to be taken to reduce or avoid possible nuisances due to the removal of spoil, the disposal of water on the surface, disturbances and noises from the work-site.

Once the construction work underground is finished it will no longer be a source of nuisances. Noise produced in the underground installations cannot be heard on the surface.

5.1.1 General

The CNGS work-site will generate both natural spoil and wastes from the demolition of existing structures and work on the site itself. Three kinds of natural spoil will be produced: topsoil, which will be stored and re-used; unconsolidated material of the moraine types; and above all molasse. The two latter types of will be stockpiled.

The work of connecting up to existing underground structures will also give rise to the demolition of concrete structures. These will be dealt with in a manner that will respect the environment.

5.1.2 Spoil

The CNGS project will generate a volume of 700 m³ of excavated moraine and 66 000 m³ of molasse, assuming a swell factor of 1.5.

Spoil is being stockpiled in accordance with the principles applied to that originating from the LHC, i.e. by avoiding passing through built-up areas. Discussions are under way with the Prévessin-Moëns municipal authority, to increase the capacity of the Bois-des-Serves storage site established to meet the needs of the LHC.

5.2.1 Concrete wastes

It is planned to break up the concrete wastes from demolition work and separate out the reinforcement so as to obtain material that can be re-used. The volume of waste from the CNGS project will be limited to 18 m³, which will come from connections to the existing structures.

5.2.2 Other site wastes

Selective waste depositories are located on site; sorting and recovery will be made by category (drainage oil, plastics, packaging, metals, etc.) and processed appropriately.

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