Internal landfill slopes strengthened with polyester biaxial grid
The construction of the Phase 3 extension to the Costessy Landfill near Norwich included slopes which adjoined existing waste slopes of a previous cell. It was therefore necessary for the site management to conform to UK Landfill Directives.
These internal waste slopes had therefore to be stabilised by reinforcing the slope during construction. Naue Geosynthetics, Secugrid ® 20/20 Q1 was deployed on to the prepared subgrade of the entire 60 metre length slopes. It was selected to stabilise and reinforce the slopes which had a gradient of 1 in 2.5.
The material is a biaxial grid, which is produced from solid extruded polyester and is stated to possess high strength and low elongation factors with the monolithic bars producing the strength essential for the type of sites where it is applied. Others features cited is that it is easy to install by excavator and spreader bar and, once in place, shows very low creep characteristics, even on the steepest slopes.
At Costessy Landfill the Secugrid 20/20 Q1 was applied to the slopes of Phase 3 in a little under a week with a total of 7,200m2 being used. Naue Geosynthetics also provided the geosynthetic clay liner (GCL) for this landfill. Some 4,000m2 of Bentofix® NSP4000-1 was installed as the secondary lining.