Environmental Engineering Reference
In-Depth Information
TABLE 3.1
ZVI Gain Size Specification for Different Types of PRB
Construction
Construction Type
Iron Grain Size (mm)
Excavation
2-0.25
Vertical hydraulic fracture
1-0.17
High-pressure jetting
0.59-0.21
Pneumatic fracturing
0.04-0.08
where
C = the outlet concentration
C
0
= the initial concentration
k = the reaction kinetic
t
= the residence time within the barrier
The reactive ZVI reaction kinetics (Equation 3.2) and formation of by-
products requires investigation by conducting laboratory batch and column
experiments (Figure 3.1), using contaminated GW from the remediation site
(Thangavadivel et al. 2013). Such experiments also help to select an appropri-
ate reactive material for the particular site application. The column experi-
ments acts as a plug flow reactor and mimic the actual GW flow conditions
within it. The reaction rate obtained from the column study can be used for
sizing the PRB barrier wall thickness L
B
as shown in Figure 3.2 (see Section
Plan view
W
Contaminant plume
L
B
Section view
H
FIGURE 3.2
PRB dimensions and design parameters, where L
B
= PRB wall thickness, W = PRB wall width,
and H = PRB wall height.
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