leachate flow in leakage collection layers due to defects in ...

GIROUD et al. D Leachate Flow in Leakage Collection Layers Due to Geomembrane Defects
4.2.2 Width of the Wetted Zone at Special Locations
The width, W o , of the parabola at the location of the defect in the primary liner is
given by Equation 36 for x = 0, and is also twice the value of OP given by Equation 22,
hence:
W
o
to
= 2
sin b
For a given leachate collection layer whose length along the slope has a horizontal
projection L, the maximum value of the width of the wetted zone occurs when the defect
in the primary liner is at the high end of the leakage collection layer slope (Figure 7),
i.e. when:
(37)
x = L
(38)
The maximum width of the wetted zone, W max , is then obtained by combining Equations
36 and 38:
W
max
2to
L
= 1+
2 sinb
sin b t
o
(39)
t o /(2 sinβ)
Defect
L
Maximum
wetted zone
A wmax
W max
Figure 7. Wetted zone when the defect in the primary liner is at the high end of the leakage
collection layer slope (truncated parabola).
Note: The case shown above is identical to the two cases shown in Figure 8 when x = L, x being the
distance between the primary liner defect and the lower end of the leakage collection layer.
232 GEOSYNTHETICS INTERNATIONAL S 1997, VOL. 4, NOS. 3-4