UNIVERSITY OF WATERLOO
Department of Civil Engineering
ENV E 477: ENGINEERING FOR SOLID WASTE MANAGEMENT
Final Examination
Winter 200?
3 hours
Open Book
Prof. J.F. Sykes
NOTES: Read the exam carefully before attempting the questions; the exam
reflects many of the steps that are followed by designers of landfills and remediation
systems. All questions will require you to determine best estimates for parameters
using the class notes and the assignments as resources. It is important that you
properly cite all parameters that you use by giving the page in the notes as a reference
or by giving the assignment question that you use as the source. If you make an
assumption, please give the basis or justification for the assumption. Note that
parameters and assumptions are acceptable when they can be adequately defended
or supported. If you use a specific method to calculate a variable, give the page
number or section in the notes for the method that you are using (i.e. reference).
Approximately 25% to 33% of the marks for a question will be allocated to the
selection of parameters and the citation of the parameter or explanation as to why
the parameter or method is appropriate.
The following data pertains to all questions:
A new landfill is to be designed for the Region of Durham. The landfill will have an
operation life of 20 years and will serve a population base of 25,000 people. The
municipal solid waste for the community is considered to have properties that are typical
of that of similar sized communities in the Province of Ontario. The average monthly
precipitation and temperature for the region (based on records from the local
Environment Canada station) are given in the following Table. The latitude for the
township is 44.0o.
Month
Jan
Feb
Mar
Apr
May
June
Temp
Precip
Celsius Fahrenheit (mm)
-7.8
56.3
17.9
(snow)
-6.2
55.6
20.8
(snow)
-2.6
78.7
28.3
6.9
74.6
44.4
13.5
81.3
56.5
16.4
84.5
61.6
Month
July
Temp
Precip
Celsius Fahrenheit (mm)
19.3
88.4
66.8
Aug
18.7
65.7
76.3
Sept
Oct
Nov
Dec
13.7
7.4
1.9
-4
56.7
45.4
35.5
24.8
89.6
77.4
85.1
76.2
(1/3 snow)
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ENV E 477 Final Exam
The stratigraphy for the proposed landfill site is 1.5 m of loam (60% silt, 20% sand, 2%
organic matter, fine granular soil structure and slow to moderate permeability) overlying
20 meters of homogeneous till overlying a homogeneous limestone aquifer. The
hydraulic conductivity for the till is 4 x 10-7 cm/sec. The depth below ground surface to
the water table in the till is 12 meters with an annual fluctuation of  0.5 meter. The
landfill bottom is to be above the water table.
The landfill design consists of 20 cells. The size of each landfill cell is determined using
the estimated volume of MSF to be placed in one year. The landfill operation begins in
the first month with an average temperature above freezing. Each completed cell is
capped at the end of the year. The average depth of waste in each cell is 15 meters at the
time of placement.
1. Estimate the mass of the municipal solid waste that will be placed in the landfill in
each year. Estimate the yearly volume of the waste and the area required for each
cell. Estimate the maximum density of the waste at the bottom of a cell. State all
assumptions. [10 marks]
2. Calculate the percolation through the landfill cover of a completed cell for any 3
consecutive months. State all assumptions. [20 marks]
3. Estimate the initial mass of chloride in a landfill cell. Using the leaching model
described in section 5.6 of the notes (page 114) estimate the leachate chloride
concentration at 10 years for the first cell. Assume that the annual percolation through
the cells with a cap is 10 cm/year and that prior to capping the annual percolation is
20 cm/year. List all assumptions in point form. [15 marks]
4. Using the leachate COD production curve given below, estimate the COD
concentration in the leachate at the end of year four (i.e. three years after the first
landfill cell is capped). Note that there will be more than one cell. Assume that the
annual percolation through the cells with a cap is 10 cm/year and that prior to capping
the annual percolation is 20 cm/year. List all assumptions in point form. [15 marks]
COD = 90,000 [1 – e-0.50 L]
COD = COD Leached in mg per kg dry MSW
L = moisture loading in L per kg dry waste
5. Estimate the Landfill Gas Produced per year for the four years after the landfill begins
operation. Assume a lag time of 2 years before gas is produced [20 marks]
6. Estimate the soil loss from the landfill after completion and the installation of a cap.
[10 marks]
2
ENV E 477 Final Exam
7. Assuming an infiltration rate of 10 cm/year, determine the specifications (drainage
layer thickness and slope, drainage layer hydraulic conductivity, pipe diameter and
spacing) for the collection pipes and drainage system above the landfill liner.
Comment on whether your design is conservative giving supporting reasons.
[10 marks]
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ENV E 477 Final Exam