Constructing Sanitary Landfill over Very Soft Ground with Very High Water Table
Designing landfill liners focused mainly in reducing the liner permeability rate and improving the contain ability of leachate within the landfills mass. Hence it is critical to have firm founding base to lay the geomembrane liner. However in the event the landfill site is location on a very soft ground with very high water table, controlling base liner differential settlement will become the key factor from preventing the liner from damage and the leachate collection system to function continuously. Even minor leakage of leachate via the damage liner could contaminate the ground water rapidly. The project site which will be discussed in the paper, is located next to Melaka river, in the state of Melaka, Malaysia.
The site consist of exiting landfill build without liner system and next to the exiting landfill site, a new sanitary landfill were required to be build. However the ground were found to be very soft with high ground water table. Hence this paper will address the design consideration adopted to save guard the environment and the measures considered to stabilize the ground to receive the new 16m high waste. Specially designed geogrid reinforced stone columns with high strength geotextile were used to support the liner and to control ground differential settlement. As for the existing landfill site, perimeter earth bund were proposed to be installed together with subsoil trench drain to intercept and collect the existing leachate mount within the landfill mass and the leached from being discharged into the Melaka river. The details of the above will be discussed in the paper.
Majority of landfill in Malaysia are an open dump site without any protection to the environment. There are a total of 176 number of active landfills in Malaysia out of which only 10 are lined and managed sanitary landfill. The rest of landfills remain as open dump. (www.kpkt.gov.my) As for current situation, the contamination of ground water are not manageable. In some cases the untreated leachate are released directly to the river, some places the rivers are drinking intake water source. It was reported that about 16 open dump landfills are next to rinking water intake. It is estimated that at least 5 % of the Malaysian population (approximately 1 million people) are living within 1 km radius from closed landfills and existing dumpsite. (Salim et al., 2003)
The Malaysian government have undertaken the task to close the existing open dump and environmentally harmful landfills and to open new manageable sanitary landfill. In some cases the new sanitary cells were open next to existing open dump site. As such the Krubong landfill in Melaka is an exercise under taken by the Malaysian government to close the exiting open dump landfill and to open up new sanitary landfill next to it. At present the flow of leachate were not managed. It is estimated about 2.5 million liters of leachate flows everyday into the ground and into adjacent water bodies, such as river, ponds and lakes in Malaysia, (Angamuthu et al. lecture note ). Hence the task for this project was to contain the leachate and prevent it from contaminating further the Melaka river. Hence it requires structured and implementation of a suitable layout plan for new sanitary landfill. Figure 1 shows the proposed layout plan for the landfill site.
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