Environmental Engineering Reference
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had to be calibrated by slightly changing the recharge rates at some points/
lines of the site: the storm water ditch south of the contaminant plume, causes
a higher recharge rate which leads to the deviation of the contaminants. The
groundwater recharge varies between +35 and −3 5 m m/a .
4.5 Scenarios
The remediation strategy applied for this study area is a combination of
active and passive remediation approaches. The active remediation includes
the pump-and-treat technology at the hot spot, that is, at the contamination
source area with passive remediation which include the large diameter PRB
wells coupled with extraction wells. Various scenarios have been calculated
considering both remediation approaches. The scenarios simulate the reme-
diation of the TCE groundwater contamination through the operation of
large diameter wells that are filled with the reactive material REMAT™. The
annular space of the wells has a large and well-defined diameter. The objec-
tive of the numeric simulations was to configure the most effective remedia-
tion plant, in order to carry out the remediation as quickly as possible and to
minimize the number of extraction and injection wells, as their construction
is expensive.
The principal problems of the site are the low hydraulic conductivity of the
sediments, the distance of the groundwater to the soil surface (11 m) and the
size of the contaminant plume (400 × 250 m). Hence, for an effective remedia-
tion, numerous large diameter wells down to depth of 20 m are needed. First
simulations indicated that the maximum pumping rate of one large diam-
eter well is only about 1 m³/d and the corresponding cone of groundwater
depression has only a small diameter (see Figure 4.5).
22.00
-10 m
-5 m
5 m
10 m
11.00
2.00
FIGURE 4.5
Calculated cone of groundwater depression and estimated range of depression.
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