Groundwater Modeling Involving PRBs: General Aspects, Case Study - Permeable Reactive Barrier: Sustainable Groundwater Remediation - page 75

the adsorption capacity of REMAT™ and therefore represent a worst-case
scenario.

4.4.4 Model Parameters

The simulation model used various parameters such as hydraulic conductiv-
ity, recharge rate, porosity, and so on, as presented in Table 4.2, to simulate the
contaminant concentrations over model domain at specified time intervals.
The values of the groundwater recharge and the hydraulic conductivity
are the first values that have been changed during the model calibration.
The parameter values were chosen according to the laboratory and field
experiments. The precision of the measurements or their variance in time
and space have not been taken into account, but their effect on the results is
discussed in the evaluation.

4.4.5 Model Calibration

Calibration is achieved by varying the groundwater recharge and the
hydraulic conductivity in the region. Reference points for the calibration on
the groundwater recharge were the regional groundwater contour map and
the TCE center line at site. In the area of the site, the hydraulic gradient of the
groundwater is very low. As a result, there are no groundwater contours in
the regional contour map. The center line of the TCE plume, however, devi-
ates from the regional flow direction toward the west; the contaminants turn
slightly toward the north. For this reason, the groundwater flow direction

TABLE 4.2
Model Parameters and Their Values
Model Parameters Values

Hydraulic conductivity, k s 5.6 × 10 −7 m/s

Recharge rate −10 mm

Groundwater flow 0.1-10 m/a

Porosity in aquifer 0.10

Porosity REMAT™ (Modell II) 0.45

Longitudinal dispersivity Dl l 0.5 m

Transversal dispersivity, D t 0.05 m

Retardation factor aquifer, R 1.56

K D value, aquifer 0.04 L/g

Solute transport TCE 0.075 −7.5 m/a

FREUNDLICH parameters REMAT™
K f 2 μg/g

N f 1.5

Degradation rate 0 s −1