4.5
Important Features of Visited Landfills
4.5.1
Leachate Management
At the sanitary landfills visited, impermeable liners were in use, usually constructed of clay, and sometimes with welded PE sheets. At the Permetang Pauh landfill in Malaysia, the clay deposits were used to reduce the release of leachate as the landfill had only introduced leachate collection after waste disposal had begun (see Box 3). In China, the Laogang (Shanghai) landfill had a base 17 m deep that achieved a permeability coefficient of 10-9m/sec. The Asuwei landfill in Beijing had improved the natural clay deposits with a bentonite liner. Artificial liners of polyethylene were applied at landfills in the Philippines, where the San Mateo and the Carmona landfills were equipped with a 2.5 mm high-density PE liner. The new sections of the Bantar Gebang landfill, Indonesia, also included a polyethylene liner. Partly situated on land that has been reclaimed by the Hong Kong government from the sea, the WENT landfill in Hong Kong was constructed with a multi-barrier liner and a leak-detection system, preventing possible leachate
flows into the sea. For the first five years of landfill operation, the private operator will not be responsible for treating leachate before it is discharged into the municipal mechanical sewerage treatment system. The municipal system, however, provides ineffective treatment of leachate. All the other landfills visited in the region had leachate collection and some form of leachate treatment. Aerated lagoons were the dominant leachate treatment method applied in the region