By Victoria Howland and Scott Turgeon


Major Qualifying Project
Stantec Project Center
◦ Center Director: Fred Hart
◦ Faculty Co-Advisor: Suzanne LePage
◦ On-Site Stantec Advisor: Tom Pace

Byproducts of coal combustion plants
can cause water and soil contamination
if not disposed of properly in a landfill.
Given an earthquake, the landfill would
be subject to various modes of failure,
releasing byproducts into the
surrounding environment.

Identify applicable stabilization methods
◦ Deep Soil Mixing
 Mixing slurry with in-situ soil
◦ Jet Grouting
 Spraying grout into the ground
◦ Slurry Trenching
 Creating a slurry wall
◦ Stone Columns
 Creating columns from stone

Decision analysis for most suitable
stabilization method

Compare methods according to area replaced

Ideally 20-30%

ARR=
𝐴𝑡𝑟𝑒𝑎𝑡𝑒𝑑
𝐴𝑡𝑜𝑡𝑎𝑙
Stabilization Method Deep Soil Mixing
ARR Value
Jet Grouting
Slurry Trenching
Stone Columns
72.80%
39.25%
58.00%
39.25%
Cost (million $)
23.00
1,061.00
290.00
22.15
Schedule (months)
77.00
930.00
107.00
31.00
Cost
Stabilization
Method
Deep Soil
Mixing
Jet Grouting
Slurry
Trenching
Stone
Columns
Pre
$2.60/ft3
$43.64/ft3
$33.00/ft3
$17.00/VLF
Post
$4.60/ft3
$11.00/ft3
$11.00/ft3
$30.00/VLF
Production Rate
Stabilization Deep Soil
Method
Mixing
Jet Grouting
Slurry
Trenching
Stone
Columns
Pre
5297 ft3/day
1833 ft3/day
267 ft3/day
375 VLF/day
Post
5000 ft3/day
6592 ft3/day
13500 ft3/day
800 VLF/day


Given cost per volume
Equipment, materials, labor
Stabilization
Method
Deep Soil
Mixing
Jet Grouting
Slurry
Trenching
Stone
Columns
Unit Cost
(cubic yards)
125
300
135
115
Matrix Value
9.20
3.83
8.52
10.00


Given production rates
Total time dependent on quantity
Stabilization Deep Soil
Method
Mixing
Jet Grouting
Slurry
Trenching
Stone
Columns
Production
Rate
(yd3/day)
185
245
500
215
Matrix
Value
3.70
4.90
10.00
4.30



Construction can be a dangerous industry
Considered construction methods, machines,
and processes for installing each stabilization
technique
Same levels of safety
Stabilization
Deep Soil
Method
Mixing
Matrix Value
10
Jet Grouting Slurry
Trenching
10
10
Stone
Columns
10



When it was invented
Previous successes and failures
Established stabilization practice
Stabilization
Deep Soil
Method
Mixing
Matrix Value
10
Jet Grouting Slurry
Stone Columns
Trenching
7
8
10


Ease of installing the technique into the
surrounding area
Proper soil conditions, space limitations, or
landmark restrictions
Stabilization
Deep Soil
Method
Mixing
Matrix Value
7
Jet Grouting
9
Slurry
Stone
Trenching
Columns
8
9

Met with client to
discuss matrix
weighting
Cost = 20%
Schedule = 20%
Safety = 15%
Proven
Technology = 25%
◦ Constructability=
20%
◦
◦
◦
◦
Metric
Cost
Relative Weighting
%
0.2
Schedule
0.2
Safety
0.15
Proven Technology
0.25
Constructible
TOTAL
0.2
1
20
%
20
%
15
%
25
%
20
100%
Deep Soil Mixing
Jet Grouting
Slurry Trenching Stone Columns
Raw Value ($/yd3)
Average
Weighted Avg
125
9.20
1.84
300
3.83
0.77
135
8.52
1.70
115
10.00
2.00
Raw Value (yd3/day)
Average
Weighted Avg
185
3.70
0.74
245
4.90
0.98
500
10.00
2.00
215
4.30
0.86
Average
Weighted Avg
10.00
1.50
10.00
1.50
10.00
1.50
10.00
1.50
Average
Weighted Avg
10.00
2.50
7.00
1.75
8.00
2.00
10.00
2.50
Average
Weighted Avg
Composite Score
7.00
1.40
7.98
9.00
1.80
6.80
8.00
1.60
8.80
9.00
1.80
8.66