The Lostallo landfill site, covering an area of around 30,000m2, is located in Lostallo, a village in the district of Moesa in the Swiss canton of Graubünden, in the Italian area of Switzerland. WALO was selected to provide a lining system at the landfill site for Cell 5, a cell of approximately 10,000m2.

The main challenge presented by this project was the extreme incline of the sides of the landfill cell. At 1:1.5, the slopes are extremely steep, which was where WALO’s particular expertise came into play as the company specialises in working on very steep slopes with specially designed machinery and highly skilled operators. In addition, environmental issues are of paramount importance in Switzerland so environmental protection of the site was absolutely crucial.

Groundwater is always vulnerable to contamination from leachate and methane, found in most solid waste landfill deposits. WALO’s Dense Asphaltic Concrete (DAC), formulated in the company’s laboratory to a design mix unique to the project, is a highly robust barrier lining system, impermeable to both of these contaminants and so was the ideal choice at Lostallo. The cell base and slopes were levelled by an excavator and a foundation layer was then placed by bulldozer, secured for working on the extreme slope by one of WALO’s 60 tonne winches. Next the clay liner (k>5×10-8 m/s), some 7-800 mm thick, was placed in two layers by WALO’s asphalt paver and main winch. The two bituminous layers – the Asphaltic Binder Layer and the Dense Asphaltic Concrete layer – were also installed by the main winch and paver and compacted by rollers on winches.