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Contenuto archiviato il 2022-11-21

Cover sealing of a blast furnace dust dump - a comparative evaluation of in situ test fields

Obiettivo

The purpose of this EC research project is to obtain data on the water balance and water movement in a cover sealing system and to quantify the functioning of different sealing systems under natural conditions. A comparative assessment is to be made of the effectiveness and cost-effectiveness of different in situ test fields.

The requirements of a cover seal are fundamentally different from those of a base liner, as they are exposed to different risks and they are used for different purposes. There are few results available on the long-term effectiveness of different capping systems. The function and effectiveness of such systems have been studied in laboratory experiments, but their results cannot simply be extrapolated to natural conditions.

The cover seal of landfills or contaminated sites has the following functions:
1. to minimize seepage of rainwater into the dump;
2. to prevent leaching of soluble contaminants into surface waters (particularly at the edges);
3. to serve as a substrate for recultivation.

These functions must be maintained in the long term, ie the cover seal must be protected from erosion, frost, drying out, clogging, settling, penetration by roots and burrowing, etc. Normally, a combination of covering layers, drainage systems and barrier layers is used to meet these requirements. Planting of the cover layers helps to protect the deeper layers from direct atmospheric and biotic attack. The cover layer and the vegetation should store a large proportion of the precipitation and/or increase its evaporation. The drainage layer below is designed to channel the water seeping in from the cover layer to the edge. The barrier layer below this can be built up of various materials:
a) plastic sheeting;
b) cohesive, mineral soil (mineral seal);
c) non-cohesive, mineral soil (capillary barrier);
d) asphalt concrete.

The Technical Instruction on Municipal Waste (regulations in force in Germany) requires a landfill site to be capped once it is full. In the case of category I landfills, a simple mineral seal is sufficient as a covering. After settling has ceased, there must be a gradient greater than or equal to 5 per cent. A drainage layer greater than or equal to 30 cm must be applied on top of the mineral seal. A 1 m thick recultivation layer must be applied on top of the drainage layer, which must consist of cultivable soil and be planted with suitable vegetation. The recultivation layer must be capable of protecting the mineral layer from root penetration and frost damage. The vegetation must provide sufficient protection against wind or water erosion. The water balance of the landfill capping system must be in equilibrium. The state of the recultivation layer and the vegetation of the closed landfill must be monitored at six-monthly intervals to detect any erosion damage, settling or deformation.

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Coordinatore

UNIVERSITÄT TRIER
Contributo UE
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Indirizzo

54286 TRIER
Germania

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