Environmental Engineering Reference
In-Depth Information
Figures 16.29 and 16.30 show the concentration in the groundwater
versus
the
number of wrinkles (with holes) in the case of pure diffusive flux (i.e. a
geomembrane without defects). The two analyzed barrier systems, of the same total
thickness, consist of an attenuation layer and a composite barrier including CCL or
GCL. The other input parameters of the examples are reported in the same figures.
Looking at Figures 16.29 and 16.30, it is possible to observe that:
− The contribution of advection on the liner efficiency due to a single wrinkle
(with holes) per hectare is negligible if organic pollutants (i.e. high diffusion
coefficient of the geomembrane) are considered. Of course, the reduction could also
be 100% in the case of an inorganic pollutant that cannot diffuse through the
geomembrane.
− For up to 10 holes per hectare the decrease in efficiency is modest; thereafter it
becomes significant, up to the maximum gradient in log scale within the 10 to 100
wrinkle range (with holes) per hectare. The comparison between Figures 16.29 and
16.30 also show that the behavior of composite liners with CCL or GCL is fully
equivalent under the assumption of the examples given.
Figure 16.29.
Efficiency of geomembrane (GM)+ CCL + attenuated layer (AL) barrier
systems versus the number of wrinkles (with holes) in the GM [MAN 00]
