Environmental recovery of a dumpsite for steelworks close to Como Lake (Italy)

The project site is located close to Lake Como (Lombardy region) and it is inside a natural reserve protected by European Regulations (Directive 92/34/CEE and Directive 79/409/CEE). The site is about 7.500 m2 and from 1972 to 1992 it was filled with wastes from steelworks.  The project objective is the environmental recovery of the site through capping and collection of rainwater to prevent infiltration.

The design activities took into consideration the criteria provided in national and international scientific literature (e.g. US EPA) and national laws and regulations, particularly in relation to isolation of the waste, minimization of the rainwater infiltration and of the erosion, prevention of local settlings, and reduction of maintenance activities.  

The interventions carried out included removal of the vegetation cover, disposal of the capping and of the drainage network, landscaping (re-vegetation).

The capping is made of: minimum of 20 cm of sand for regularizing the terrain, geotextile 400 g/m2, 50 cm of compacted clay, geotextile 600 g/m2, 20 cm of rounded gravel (Ø 40-60 cm) (i.e. the drainage layer), geotextile 400 g/m2, and 20 cm of topsoil for the landscaping. 

The compacted clay is the waterproofing layer; it permits reaching the permeability of 10-9 m/s. The layer has been combined with a bentonite geocomposite (permeability of 10-11 m/s) where the thickness of 50 cm needed to be reduced.

The collection of rain water will be performed through the drainage layer and to the network of prefabricated ducts (486 m length), laid on the clay layer, to deliver the water to a ditch located along the west side of the site.

Given the location of the site, the landscaping activities represented an essential element of the project. Native species were re-introduced in the site, according to local regulations and to the Master Plan of the natural reserve in which the site is located.