The advantages of this solution can be summarised as follows:

- The emission of the smell coming from fresh waste can be contained in a shorter period of time and with a bigger effectiveness than covering the waste materials with earth.
The laying of the sheet is a procedure that can be made in a short period of time and soon after the end of the waste materials conveyance. If it is opportunely planed the procedure can be quite simple. Unlike the distribution of earth there are not discontinuity part of the ground or places where you can find a lesser thickness or places where you have a mix of earth and waste material.

- Reduction of fine material supply that as everyone knows can be the cause of waterproof parts both on the bottom (obstruction of drainage system) and inside the layers (formation of suspended stratum).

- Elimination of the land supply and of the relative acquisition cost, storage and distribution.

- Increase of the useful volume of the site, that can be completely used to the conveyance of the waste material, without the volume loss consequent on the inert material giver-on.

SUMMARIZING DIAGRAM OF ECONOMIC ADVANTAGES

Better exploitation of the volume in the landfill

We want to concentrate the attention on this subject of particular economic size, seen that the amount of volume that is possible to earn corresponds in direct mode to the increase of the landfill income.

Assuming a waste materials layer with a thickness of 1 m, with a cover of inert material with a thickness of 10 cm, apparently we are in front of a loss of useful volume equal to the 9%. Considering a good compacting of the waste materials in placed (600 Kg/m3) and a conferment value equal to Euro 77,47/t, the economic loss for the only loss of useful volume is equal to 46.481 Euro per hectare.

In fact the value is definitely superior, seen that the garbage undergoes arrangement of diversified nature that bear to a strong reduction point of the disposition of volumes; in the immediately following months to the conveyance for:

- crushing of the inert material capable of being deformed and compression of the empty spaces following the weight of the layers subsequently laid upon;

- decomposition of the organic substance in the following 20 years, with transformation of the solids in bio-gas (about the 30% of the mass) and in leachate (another 5%).

After 15 years of activity the long term experience calls an apparent density of 1200÷1400 Kg/m3; the drastic consequent disposition of volumes reduction is for the nearly whole due to the waste materials, seen that the inert material has a negligible compressibility, and it doesn't decompose.
In practice it has been possible to calmly affirm that the inert material, at the end of the life of the landfill, they will occupy an equal volume to about the 20% of those available profit, and the lost economic value for hectare will be estimated in 77.500÷93.000 Euro for each layer.

On a landfill of 3 hectare and a depth of 40 m, against a possible gross conveyance of about 1.440.000 t (value 111.039.954 Euro), there will be a real conveyance of only 1.296.000 t (value 100.192.639 Euro) with a loss of taking equal to 11.362.228 Euro.

From the collective point of view we have to consider that the greater quantity of waste materials conferred (144.000 t) represents the supply of a town of 100.000 inhabitants for nearly 4 years, with the relapse that this can have in political and image terms for the local administration.

Conclusions

In brief the elimination of the daily covering with land, and its substitution with a system of absorbent materials, represents an advantage both for the collective nature and for the management. This is a solution absolutely not pejorative (the control of smell is comparable, if not superior, the risks relative to the management of leachate and bio-gas, etc. are reduced); it is not absolutely a contrast to the legal rules tendency in the field of the landfill.

A careful examination of the relative advantages in the single situations must be already a part of the design procedure of a new installation, and it can have a prominent interest also for that one already in use.