References

Passive confinement of a former industrial waste disposal site

FRANCE, 2006

Total confinement of a former agrochemical site in Beaucaire.

This former agrochemical site was operated for the manufacture of herbicides and pesticides in the commune of Beaucaire until 1996. The waste produced by the manufacturing operations was stored in a former gravel pit adjacent to the site. The solution selected and approved by the authorities, for financial as well as health and safety reasons, consisted of confining the site rather than evacuating the waste to a class 1 landfill site.




The preparatory work involved the shifting of the waste in order to establish an operating platform to protect the operating personnel from the pollutants and provide the perfect stability required by the drilling equipment.

The 135m long boundary slurry wall was constructed by Solétanche Bachy using a cable bucket operated on a tiny patch of land of just 900m2. The wall is anchored in the marl at its base at a depth of between 16 and 20m.

Since the geomembrane waterproofing system is located 1,5m below the natural earth level, the top of the wall was reinforced using metal sections; an additive was introduced into the bentonite-cement slurry to improve its resistance to compression which was increased to 2 Mpa after 28 days and to make it possible complete the earthworks in total safety. The geomembrane waterproofing system also helps drain any penetrating water which is channeled to the waterway in the trench running alongside the nearby main road.
The excavated volume was then filled with clean, well-draining materials up to the natural earth level. The surface layer consists of humus.

The long-term monitoring of the confinement is ensured by a network of boreholes and piezometers welded to the horizontal waterproofing system.

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Techniques

Groundwater and impermeabilty

Groundwater is one of the most complex issues to be resolved in geotechnics. During the start phase of a project, the proper techniques have to be chosen for building any cut-off walls that might be required, pumping (wells, filter points, etc.) and monitoring (piezometers) resources.

Protection of the environment

Soletanche Bachy, and its subsidiary Solenvironment, provide solutions for pollution issues, involving, for example: inertisation of waste, rehabilitation and treatment of polluted sites, cleaning of discharge to required environmental control levels, construction of waste storage facilities, protection of groundwater.

Ouvrages

Environment

Through his subsidiary Sol Environment, Soletanche Bachy provides solutions to various pollution problems: stabilisation of waste, rehabilitation and treatment of polluted sites, cleaning of discharge to required environmental control levels, construction of waste storage facilities, protection of the water table.


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