Kouli_etal_2008_Groundwater modelling_BOOK.pdf - Pantelis ...

100
Sabrina Saponaro, Sara Puricelli, Elena Sezenna et al.
Fig. 9 shows air pressure P g at stationary conditions over a semi-section parallel to the
XZ plane passing through P SVE , for simulations where P SVE was active at different extraction
flow rates (Q V,SVE : -60 to -150 Nm 3 h -1 ); the maximum value in the color scale is the air
pressure at water table. At the boundary on the right of each figure, P g results in values as for
natural conditions (no influence of P SVE ). As ⎪Q V,SVE ⎪ grows the depression cone next to the
screened part of P SVE enlarges, resulting in the minimum value (1.011 10 5 Pa) for the highest
absolute value flow rate which has been simulated [Fig. 9(e)]. For⎪Q V,SVE ⎪ ≥ 90 Nm 3 h -1 , a
depression zone is shown next to P SVE at ground surface (top boundary in the figures),
suggesting that atmospheric air is sucked into soil.
Fig. 10 shows air velocity vectors v g at stationary conditions when P AS and P SVE are
contemporarily operating as in the full-scale treatment performed at the site. SVE well (thick
green line on the left) sucks air from g.s. into the top of the screened part of the well and from
soil into the bottom part. The air injected by the AS well (thick orange line on the right)
flowing through the ZOT AS (S g ≥ 0.1, within the white contour) is completely captured by the
extraction well, even if a small amount of air flowing through the ZOI AS (S g ≥ 0.01, beneath
water table under natural conditions) escapes the collecting system.
Figure 10. Air velocity vectors (v g ≥ 1 10 -4 m s -1 ) at stationary conditions when P AS and P SVE are
contemporarily operating (injection flow rate in P AS : Q V,AS,pil ; extraction flow rate in P SVE : Q V,SVE,pil ) over
an axonometry showing planes passing through the centre of the contaminated zone in soil [α and β in
(a)]. Planes γ and δ in (a) are parallel to the XZ plane and delimit pollution in soil along X direction. On
plane β, polluted soil is enclosed within the dashed brown line. ZOT AS (S g ≥ 0.1) is enclosed within the
white oval.
Under the same operating conditions of Fig. 10, Fig. 11 shows results over the section
parallel to the Y’Z plane passing through P AS (thick orange line on the left) and P SVE (thick
green line on the right) [Fig. 11(a)]. In the lower part of Fig. 11(b), beneath water table under
natural conditions (triangle on the right boundary) S g varies between 0.01 and 0.2. The white
oval shows the ZOT AS of P AS . In the upper part of Fig. 11(b), the air pressure P g is shown as a
scalar ranging between 1.0115 10 5 Pa and the value at water table under natural conditions