Environmental Engineering Reference
In-Depth Information
Table 3
MTE average and maximum contents in basins sediments
Element
Average
Maximum
Cadmium
043
1.5
Lead
79
550
Zinc
190
1620
Chrome
43
210
Copper
Nickel
Geotechnic characteristics:
The first parameter making it possible to classify a
soil is the organic matter content. Data from literature and sample campaigns show
a slight organic matter percentage in sediments from ditches. These sediment
characteristics stay about 5% for variability in the range 3.4%-6.6%. Conversely
basins present contents in the order of 10% for a variability range from 3% to
37.5%. It is so convenient to foresee a treatment aiming at pull down organic matter
before any reuse, by liming or landfarming. The later treatment has moreover the
advantage of offering a hydrocarbon degradation possibility.
Grain size, the second main parameter, has been studied on both sediment typolo-
gies: materials being likely to present a large fine particle content, only laser grain size
analyses are presented here. Grain size composition near to in-site soil in road ditches
is observed. The possibilities of reusing these sediments in engineering depend on the
local geological context. Sediments from basins all present important percentages of
particles inferior to 80 mm (Table
4
), indicating a very water sensitive material.
Moreover, variability within samples is very important (Fig.
4
). Before any reuse
of these materials in engineering, it is convenient to:
-
Diminish the organic matter content
-
Reduce moisture
-
Homogenize the material
As indicated above, one of the two discriminating parameters for reusing
sediments in engineering is moisture. The simple device is presented in
material and methods. Classically, three phases (Fig.
5
) are observed during
the experiment:
Table 4
Geotechnical characteristics of different basin sediments
Sample
Particles above 80 mm (%)
Moisture
B6-B4
22.9
40.9
B17
62.7
101.9
B27
23.7
4.7
Cheviré Sud
[6]
35.9
-
