Sanitary Landfills: Toward Sustainable Development - lumes

LUMES 2000-2001
Sanitary Landfills: Toward Sustainable Development
i) Base liner system that will contain leachate within landfill and prevent the leachate
percolate through the landfill cell and contaminate the ground water
ii) Leachate collection system that will remove the leachate
iii) Leachate treatment system that will remove organic matter from the leachate
iv) Daily soil covering to avoid flies and vectors breeding
v) Final cover or top liner that will reduce infiltration and promote runoff
vi) Diversion of surface runoffs around site to prevent water from filtering into the landfill
vii) Gas venting to prevent and/or reduce landfill gases migration
viii) Buffers at the boundary of the site
ix) Internal drainage
x) Proper access roads
Liner design, in particular, should follow a set of rigour measures in order to prevent any possible
leachate leakage and nearby surface water and groundwater contamination. Leachate collection
and gas venting facilities are no less important in minimising the landfill environmental impacts.
3.1.2.1 Lining and Capping
In order to prevent leachate from polluting the surface water and ground water, there are two
alternative landfill management strategies that can be adopted for leachate control:
i) A site that is engineered to contain waste and leachate. The liner system consists of a
composite base liner system of a soil and geo-membrane component overlaid by a geosynthetic
leachate collection layer.
ii) A site that allow leachate attenuated slowly by natural process. The liner system consists
of a soil base and granular leachate collection system
The composite base liner consists of an upper geomembrane liner and a lower compacted soil. In
United States the minimum requirement for the geomembrane is at least 30mm thick, and if a
high density of polytheylene (HDPE) geomembrane is used, the minimum thickness required is
60mm. The compacted soil liner must be at least 60cm in thickness and with a hydraulic
conductivity of less than 1 x 10 -7 cm per second (USEPA, 1994). But as concerned by Allen
(2001), the lifespan of the landfill liner is yet to be sure and there is a high probability that the
leachate could form and leach through the artificial liner as the liner deteriorates along time and
the interaction with the chemical components in the landfill cell. He suggested that the landfill
should be situated at land with natural hydrogeological characteristics which can contain and
naturally attenuate contaminants to acceptable level instead of trying to contain the contaminants
within the landfill by relying on artificial liners.
A final cover or cap is important in landfill design too. It should be designed in a way that can
reduce infiltration and promote runoff and evaporation. In order to do so, a low permeable or
impermeable liner will be laid on top of the waste. Runoff control is essential because it can carry
leachate near the surface of the landfill to nearby surface water sources, such as streams or rivers
and cause contamination.
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