# Chapter 11 FE Problem Solutions

```Chapter 11 FE EXAM FORMATTED PROBLEMS
11-1. A field test of a clay liner resulted in the data shown below. Estimate the hydraulic
conductivity of the liner.
Thickness of the clay line=0.60m
Clay porosity= 0.55
Breakthrough time = 90.0d
Depth of leachate above the liner = 3.0m
Solve using Eq. 11-12.
K
T 2
(0.6m) 2 (0.55)

 6.11  10 4 m / d
t ( H  T ) 90 d (3m  6m)
(6.11  10 4 m / d )(100 cm / m)(1d / 86400 s )  7.07  10 7 cm / s
11-2. Estimate the percent of landfill gas that is methane for a rapidly decomposing waste with
the following composition: C68H111O50N, assume the maximum theoretical landfill gas may be
estimated using Eq. 11-9.
(4)(68)  111  2(50)  3(1)
 35moles
8
4(68)  111  2(50)  3
CO2 
 33moles
8
NH 3  1
CH 4 
Total  35  33  1  69 moles
%CH 4 
35moles
(100 %)  51%
69 males
11-3. Solid waste with the density of 110 kg/m3 is spread in a 0.5m layer at a landfill. If a steel
wheeled compactor can achieve a density of 400 kg/m3, what thickness of waste will be
achieved?
 110 kg / m 3 


 400 kg / m 3 (0.5m)  0.14 m


11-4. Estimate the weekly volume of solid waste being delivered to a municipal landfill if the
average solid waste generation rate is 2.6 kg/person∙d. The population is 17,200 and the
density as delivered is 122kg/m3.
(2.6kg / person day)(7d / week)(17,200 people)
 2565 .90m3 / week or 2,600m 3 / wk
3
122 kg / m
```