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Environmental recovery of a dumpsite for steelworks close to Lake Como
The project site is located close to Lake Como (Lombardy region) and is inside a nature reserve protected by European Regulations (Directive 92/34/EEC and Directive 79/409/EEC). The site covers about 7,500 m2 and from 1972 to 1992 it was filled with waste from steelworks.
The project objective is the environmental recovery of the site through capping and collection of rainwater to prevent infiltration.
Location: Lombardy Region, Italy
Client: Infrastrutture Lombarde S.p.A.
Cost of total Works: 1,280,000.00 €
Services: Preliminary Design, Detailed Design, Final Design, Environmental feasibility report, Landscape report, Monitoring plan of underground waters and Assistance to the client during the preliminary investigations for approval
Period: 04/2012 – 07/2012
The design of the recovery works include the waterproofing covering ("capping") and the provision of a plan for the groundwater monitoring of the entire area where the site is located.
The project area is included in a wetland of international importance "Pian di Spagna" Nature Reserve and Lake Mezzola, coinciding with SCI-SPA IT2040042, belonging to the Natura 2000 network, protected by Directives 92/43/EEC and 79/409/EEC.
The design activities took into account the criteria provided in national and international scientific literature (e.g. US EPA) and national laws and regulations (Legislative Decree 36/03 as amended), particularly in relation to isolation of waste, minimization of the rainwater infiltration and of the erosion, prevention of local settling, and reduction of maintenance activities.
The interventions carried out have included removal of the vegetation cover, disposal of the capping and of the drainage network, landscaping (revegetation).
The criteria considered in the design of the layers of the waterproofing cover are: isolation of ash and slag from the external environment, minimizing water infiltration, reducing the need for maintenance, minimizing erosion, resistance to local settling phenomena.
The capping is made of: minimum 20 cm sand for regularizing the terrain, 400 g/m2 geotextile, 50 cm compacted clay, 600 g/m2 geotextile, 20 cm rounded gravel (Ø 40-60 cm) (i.e. the drainage layer), 400 g/m2 geotextile, and 20 cm topsoil for 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 50 cm thickness needed to be reduced.
The rainwater will be collected through the drainage layer and the network of prefabricated ducts (486 m length), laid on the clay layer, so as to deliver water to a ditch located along the west side of the site.
Given the location of the site, the landscaping activities have 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 nature reserve where the site is located.
The project was delivered at the end of January 2013; it was scheduled for completion within 4 months with a break in the period between March and June to avoid disturbing bird nesting.