Environmental Engineering Reference
In-Depth Information
•
Leachability
•
Durability
Most projects have specified criteria for these properties. Chapter 11 describes
the laboratory procedures to measure these properties. However, there is currently
no official document specifying the QA/QC procedures for sampling and curing
field samples for these tests.
12.9
QUALITY CONTROL CHART FOR S/S
In order to ensure formulation of the treated waste within the acceptable range,
quality control charts can be developed for daily operations. Rushbrook et al.
28
developed a S/S quality control chart based on five physical and leaching parameters:
(a) setting rate; (b) compressive strength; (c) hydraulic conductivity; (d) contaminant
leachability; and (e) liquid retention. In a laboratory study, a variety of treated wastes
containing varying proportions of cement, liquid and solid wastes, and pulverized
fly ash (PFA) were prepared. After a series of tests on the treated wastes, a quality
control chart for an acceptable waste proportion was developed (Figure 12.3).
12.10
EARLY FAILURE INDICATORS AND
ADJUSTMENTS TO THE MIX DESIGN
At the moment, there are no official documents that describe the monitoring of the
treated wastes for an early indication of failure. However, the following measures
may be used as early failure indicators:
29
Arbitrary selection of minimum constraints:-
Setting rate - penetrometer depths:
0
100
10
90
≤
1.5mm after 7 days.
0.5mm after 28 days.
Hydraulic conductivity:
≤
Heavy metal concentrations
in leachates are not drawn
on this figure
20
80
2.0 x 10
-5
cm s
-1
after 7 days.
≤
30
70
17
1.5 x10
-5
cm s
-t
after 28 days.
Supernatant retention:
1
9
≤
40
60
13
5
2
10
6
18
20
10 days above
level sample
at 15 to 20
≤
15
50
50
1
16
C
Compressive strength:
°
3
7
60
40
1 MPa after 28 days
Zone of acceptable waste
proportions
≤
4
8
1
70
30
80
20
90
10
100
0
0
10
20
30
40
50
60
70
80
90
100
% cement
FIGURE 12.3
Quality control chart for acceptable proportions of treated waste.
28
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