chapter 4: temperature inside the landfill

the waste. This phenomenon declines once waste starts to settle and collapse due to
biodegradation. Furthermore, because of the channeling, internal storage capacity of the landfill
is not effectively used. If all the absorptive capacity of the waste is used, leachate quantity
produced will be less and leachate generation will occur around the time predicted by the models
and better management practices can be planned and applied to manage it. The reduction in
leachate quantity will minimize the cost of onsite storage, transportation and offsite treatment of
the leachate (Reinhart and Townsend, 1998).
2.3.1 Unsaturated leachate flow
The moisture movement inside a landfill is generally the unsaturated flow except some
instances such as leachate ponding on the landfill bottom (Reinhart and Townsend, 1998). The
hydraulic conductivity in landfills is governed by the suction head, and therefore the moisture
content. Darcy’s law for one-dimensional downward flow in unsaturated zone is as follows
(Reinhart and Townsend, 1998):
∂θ
q = −K
( θ ) − D(
θ )
∂Z
Where, q is the volumetric flow rate per unit surface area, K is the hydraulic conductivity,
and D is the diffusion coefficient.
The continuity equation is expressed as:
∂θ
∂q
+ = 0
∂t
∂t
Combining the above two equations, Richard’s Equation is obtained:
8
(2-3)
(2-4)