A SLOPE FAILURE and the need for more space at one ofnorthern France's biggest landfills provided a showcase for a new geogrid.
Intense rainfall last year triggered a failure at the Hersin Coupigny landfill, which lies in a huge chalk pit. At the time, the landfill authority was looking to increase space at the toe of the slope to create more storage.
Contractor Patroux addressed both issues by building a 16m-high reinforced soil steep slope, with technical support from Colbond Geosynthetics.
Colbond saw the project as an excellent showcase for its Enkagrid PRO, introduced last year. It says the product combines the properties of flexible woven polyester grids and the stiff extruded polyethylene grids.
Made up ofhighly oriented extruded polyester straps which are welded together by laser technology, the resulting geogrid is claimed to have excellent durability and longterm performance.
In particular, says Colbond, its structure and material properties makes it very resistant to the aggressive environments encountered in landfills. Colbond Geosynthetics engineer Alain Herault worked on the design of the benched steep slope structure using the French software program Cartage.
Enkagrid PRO 40 and Enkagrid PRO 60 (with a quality control strength of 40kN/m and 60kN/m respectively) were selected as the most suitable for the steep slope, which was built with crushed mudstone.
Construction took place in May, and Colbond reports that the contractor was surprised by the ease ofhandling and installation.
'Although the new geogrid can be considered as stiff, the flexibility of the straps made the contrac tor 's l i fe much eas ier, ' sa id a company spokesman.
Patroux installed more than 15,000m2 in less than a month.