City of Bayreuth
Ing.-Ges. COPLAN AG, NL Weiden BEN Umwelt GmbH
TS BAU GMBH, NL Jena, F & T Müller, Ipsheim
March till September 2015
The Heinersgrund landfill site is situated in the city of Bayreuth which is in the Ramsenthal district, Bindlach community. Since 1994, the landfill has been used as a residual waste landfill for waste up to landfill class II. To date, approximately 1 million m³ of waste has been stored on the 12-hectare site. The old part of the landfill is enclosed by a sealing wall that binds into the clay.
Only the area for DK II waste, located on the north-east side of the landfill was available, however, this area is now no longer available. The plan was to create new deposition volume on site. Section A of the landfill is mainly located on a soil of sand and sandstone. At the same time, additional landfill volume for Class II waste is to be created on a part of the old landfill (landfill on landfill).
However, the subsoil for the transition to the intermediate sealing layer/base liner system, which is created later, consists of old deposits of the most varied composition. As a result, areas with different load-bearing and deformation behaviour interact with each other.
The city of Bayreuth, represented by the civil engineering office, carried out the extension of the landfill section A with a bottom lining system according to the regulations of the DepV for waste of landfill class II in cooperation with the engineering company COPLAN AG. The planned sealing of the base in landfill section A was carried out on a natural surface to be pre-profiled, as well as on a partial surface of the existing waste deposits. The total area was approx. 10,000 m² and this included the bottom and the embankments. The intermediate sealing in the west of the site, adjoining the base, was created in the adjacent area as well as in the transition area of the current backfill zone with surface sealing to be carried out in the north.
With the help of the geogrid Fortrac R 80/25-20/30 MPT (made of alkali-resistant polyvinyl alcohol) the problems arising in the transition area from the new bottom lining system to the old landfill were solved.
The calculations, carried out in advance, resulted in a necessary nominal strength, of the geogrid, of 80 kN/m in the longitudinal direction with an elongation at a break of less than 6%.
At the same time, a permanent chemical resistance (pH > 2 to pH < 13) under load was required for the reinforcement grid, since it can come into contact with waste materials and contaminated eluates. Due to using the extremely flexible Fortrac geogrid, space-saving and UV-protected storage of 8 m long overhangs was also achievable for the section constructed later at the edge of the site (approx. 0.5 m wide, approx. 2 cm high).
The protection of the geomembrane against damage was achieved with the BAM-approved protective nonwoven HaTe, type B 1200 “O” II used in combination with recycled sand, i.e. with already contaminated waste materials and without the additional costs of natural building materials. The protection of the drainage layer against penetrating fine particles was achieved by using a separating nonwoven HaTe, type B 300 “O” II. This made it possible to dispense with an otherwise necessary, but much more grain graded layer, which reduces the landfill volume.