A modern controlled landfill is designed and created with the main aim of preventing any possible contamination of the environment, both during the time the site is being filled and after it has been capped. In addition, once the fill is complete, the site must be made to blend in as far as possible with the surrounding environment so as to minimize its impact on the character of the landscape.
Bottom barrier
The main function of the bottom barrier is to protect the subsoil by physically separating the waste from the ground beneath, and favouring the drainage and collection of percolating liquids; the core of the barrier will consist generally in one or more layers of compacted clay coupled with one or more geomembranes. The geomembrane can be protected against contact with materials that could cause damage by applying a non-woven geotextile of the GEODREN range. Regulations state that percolating liquids must be drained by laying a bed of gravel at least 50 cm deep; this can be substituted (or accompanied) to good effect by a drainage geocomposite such as SINTEXDRAIN, which will guarantee the same permeability as natural aggregate even when subjected to appreciable overloading.
Capping
This final component of the landfill must guarantee two essential functions: ensuring that rainwater can run off freely, without penetrating the bulk of the buried material, and capturing the biogas produced by the decomposition of organic waste. In both cases, current regulations state a requirement for layers of gravel at least 50 cm deep, which in practice dictates the need for considerable quantities of aggregate, lengthy installation procedures and a reduction of the maximum landfill capacity. Instead, gravel can be replaced by drainage geocomposites of the SINTEXDRAIN range, providing an alternative method that is no less effective technically, and also minimizes the environment impact, besides reducing the cost of installation and maximizing the cubic capacity of the landfill, by virtue of the shallower capping.
Slopes
The slopes of a landfill must perform the same functions as the capping, and accordingly, will be designed with a very similar layered covering. Often, however, circumstances call for the construction of steep gradients, dictated both by the contours of the terrain and by the need to maximize the capacity of the landfill. Accordingly, the deployment of an appropriately proportioned geogrid package, using EDILGRID type products, can help considerably to stabilize these slopes.
Another important aspect is the need to control the erosion of the soil used for the final capping, especially where steep gradients are in play. In these situations, the use of a geomat like SINTEXMAT, or of JUTENET and STRAWMAT biomats, will ensure stabilization and protection of the top layer, as well as providing a surface on which vegetation can take root more easily and blend with the surrounding environment.
