Kouli_etal_2008_Groundwater modelling_BOOK.pdf - Pantelis ...

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Sabrina Saponaro, Sara Puricelli, Elena Sezenna et al.
Model Verification
The model was verified by comparing pilot test simulations and field measurements.
Concerning AS test, field water mounding Δh l in P AS and PZ AS was interpreted as water
pressure increase with respect to natural conditions at a depth equal to half of the screen wells
(-23.5 m g.s. for P AS , -20.5 m g.s. for PZ AS ); since no porous materials are present in wells, P c
is negligible and P l = P g , therefore Δh l can be calculated from simulation results as the
variation between P g at time of concern and natural condition, divided by (ρ l g). Δh l resulting
from the model was plotted versus the distance from P AS ; through linear extrapolation to Δh l
= 0, ZOI AS,pil from model resulted in 8.3 m [Fig. 7(a)], in agreement with field data.
Figure 7. Linear extrapolation of Δh l during the AS pilot test (a) and ΔP g during the SVE pilot test (b)
vs distance from injection/extraction well (>: value from the model at the monitoring wells; ---: linear
interpolation).
Concerning SVE pilot test, ΔP g was obtained as the difference between the P g value at
stationary conditions under operation and P g at natural conditions resulting at half depth of
the screen of the monitoring wells PZ SVE (-8.5 m g.s.); these values were plotted as a function
of the distance of PZ SVE from P SVE , and linearly extrapolated to ΔP g = 0 Pa, resulting in a
simulated ZOI SVE,pil = 17.6 m [Fig. 7(b)], in agreement with field data.
AS and SVE Flow Rates
Fig. 8 shows air saturation at stationary conditions over a semi-section parallel to the XZ
plane passing through P AS , for simulations where P AS was active at different injection flow
rates (Q V,AS : 5 to 20 Nm 3 h -1 ). The isoline S g = 0.01 (or S l = 0.99) delimits water saturated
zone; S g = 0.20 is the maximum value of gas saturation resulting from the simulations. The
dashed black line shows water table at natural conditions (no air injection), the brown one
delimits pollution in soil. As expected (USACE, 2008), as Q V,AS grows the extension of the
zone nearby P AS partially saturated by air becomes larger; nevertheless, S g values higher than
0.1 (black continue line) can be obtained only for Q V,AS ≥ 10 Nm 3 h -1 next to the screened part
of P AS .