The landfill was remediated by capping the landfill body with a surface sealing system and a landfill gas capturing facility.
The old section of the landfill Lübben (5.4ha) was in operation from 1978 until 2005. Overall, a volume of 920.000m3 waste was disposed, containing construction (57%), municipal, and household-type commercial waste. A geological barrier or a base liner does not exist. At the site the groundwater level is high and vulnerable for pollution. After the closure of the landfill, the remediation of the site was obligatory. As the volume of the landfill body exceeds 500,000m3 the technical design of the remediation had to be in line with the requirements for the landfill class II of the German landfill ordinance. The landfill body was covered by a surface sealing system with two sealing elements. The surface sealing system consists of • adjustment/bearing layer, 0.5m (works as gas collection layer) • geosynthetic clay liner (natrium bentonite mat, weight 5000g/m2) • geomembrane, 2.5mm, HDPE • polymer drainage element • cushion layer (sand, 15cm), • recultivation layer, 1.00m • vegetation. Furthermore the remediation measures include • a landfill gas capture facility, consisting of a landfill gas capturing layer under the sealing system, 15 gas wells and a flare • a surface drainage system • traffic infrastructure around and on the landfill • facilities to measure settlement of the landfill body • groundwater observation wells. In the design of the capping the bentonite mat can be substituted by a mineral liner >0.5m, the polymer drainage element by a mineral drainage layer >0.3m.
Resources needed
The financial resource needed for the remediation measures was € 1,937,838. The measure was funded by ERDF with € 750,800. The remaining part was paid by the landfill operator.
Evidence of success
The capping of the landfill restricts water infiltration into the contaminated landfill body and reduces the potential for contaminants to leach from the site into the groundwater. This is crucial as a base liner does not exist. The combination of two different sealing elements gives redundancy in the case of technical defect of one sealing element. The two liners installed have a 100-year warranty.
Difficulties encountered
This practice requires a significant knowledge and experience of planning and construction of landfill sealing systems. A quality management has to be implemented to control the quality. Afterwards, maintenance works have to assure that no deep-rooting trees grow, harming the impermeable liners.
Potential for learning or transfer
About 500,000 landfills exist in the EU. The EU landfill directive is decisive for the minority of the landfills (< 10%). Despite of the huge number of landfills, no information of remediation is given in the directive and there is no technical guideline or handbook on European level. This good practice describes an example for remediation of a landfill. It is replicable for large-scale landfills, where disposed waste may have harmful effects on groundwater. The design of the capping with a bentonite mate and geomembrane is advantageous in areas, where no natural resources such as clay for mineral liner are available.
The design of the capping is appropriate particularly for older landfills without a base liner and where an effective protection of the environment from landfill caused contaminants is necessary.
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